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Sample records for hsd17b locus centromeric

  1. Genetic variation in the HSD17B1 gene and risk of prostate cancer.

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    Peter Kraft

    2005-11-01

    Full Text Available Steroid hormones are believed to play an important role in prostate carcinogenesis, but epidemiological evidence linking prostate cancer and steroid hormone genes has been inconclusive, in part due to small sample sizes or incomplete characterization of genetic variation at the locus of interest. Here we report on the results of a comprehensive study of the association between HSD17B1 and prostate cancer by the Breast and Prostate Cancer Cohort Consortium, a large collaborative study. HSD17B1 encodes 17beta-hydroxysteroid dehydrogenase 1, an enzyme that converts dihydroepiandrosterone to the testosterone precursor Delta5-androsterone-3beta,17beta-diol and converts estrone to estradiol. The Breast and Prostate Cancer Cohort Consortium researchers systematically characterized variation in HSD17B1 by targeted resequencing and dense genotyping; selected haplotype-tagging single nucleotide polymorphisms (htSNPs that efficiently predict common variants in U.S. and European whites, Latinos, Japanese Americans, and Native Hawaiians; and genotyped these htSNPs in 8,290 prostate cancer cases and 9,367 study-, age-, and ethnicity-matched controls. We found no evidence that HSD17B1 htSNPs (including the nonsynonymous coding SNP S312G or htSNP haplotypes were associated with risk of prostate cancer or tumor stage in the pooled multiethnic sample or in U.S. and European whites. Analyses stratified by age, body mass index, and family history of disease found no subgroup-specific associations between these HSD17B1 htSNPs and prostate cancer. We found significant evidence of heterogeneity in associations between HSD17B1 haplotypes and prostate cancer across ethnicity: one haplotype had a significant (p < 0.002 inverse association with risk of prostate cancer in Latinos and Japanese Americans but showed no evidence of association in African Americans, Native Hawaiians, or whites. However, the smaller numbers of Latinos and Japanese Americans in this study makes

  2. Next generation sequencing with copy number variant detection expands the phenotypic spectrum of HSD17B4-deficiency.

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    Lieber, Daniel S; Hershman, Steven G; Slate, Nancy G; Calvo, Sarah E; Sims, Katherine B; Schmahmann, Jeremy D; Mootha, Vamsi K

    2014-03-06

    D-bifunctional protein deficiency, caused by recessive mutations in HSD17B4, is a severe, infantile-onset disorder of peroxisomal fatty acid oxidation. Few affected patients survive past two years of age. Compound heterozygous mutations in HSD17B4 have also been reported in two sisters diagnosed with Perrault syndrome (MIM # 233400), who presented in adolescence with ovarian dysgenesis, hearing loss, and ataxia. An adult male presented with cerebellar ataxia, peripheral neuropathy, hearing loss, and azoospermia. The clinical presentation, in combination with biochemical findings in serum, urine, and muscle biopsy, suggested a mitochondrial disorder. Commercial genetic testing of 18 ataxia and mitochondrial disease genes was negative. Targeted exome sequencing followed by analysis of single nucleotide variants and small insertions/deletions failed to reveal a genetic basis of disease. Application of a computational algorithm to infer copy number variants (CNVs) from exome data revealed a heterozygous 12 kb deletion of exons 10-13 of HSD17B4 that was compounded with a rare missense variant (p.A196V) at a highly conserved residue. Retrospective review of patient records revealed mildly elevated ratios of pristanic:phytanic acid and arachidonic:docosahexaenoic acid, consistent with dysfunctional peroxisomal fatty acid oxidation. Our case expands the phenotypic spectrum of HSD17B4-deficiency, representing the first male case reported with infertility. Furthermore, it points to crosstalk between mitochondria and peroxisomes in HSD17B4-deficiency and Perrault syndrome.

  3. The Hydroxysteroid (17β) Dehydrogenase Family Gene HSD17B12 Is Involved in the Prostaglandin Synthesis Pathway, the Ovarian Function, and Regulation of Fertility.

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    Kemiläinen, Heidi; Adam, Marion; Mäki-Jouppila, Jenni; Damdimopoulou, Pauliina; Damdimopoulos, Anastasios E; Kere, Juha; Hovatta, Outi; Laajala, Teemu D; Aittokallio, Tero; Adamski, Jerzy; Ryberg, Henrik; Ohlsson, Claes; Strauss, Leena; Poutanen, Matti

    2016-10-01

    The hydroxysteroid (17beta) dehydrogenase (HSD17B)12 gene belongs to the hydroxysteroid (17β) dehydrogenase superfamily, and it has been implicated in the conversion of estrone to estradiol as well as in the synthesis of arachidonic acid (AA). AA is a precursor of prostaglandins, which are involved in the regulation of female reproduction, prompting us to study the role of HSD17B12 enzyme in the ovarian function. We found a broad expression of HSD17B12 enzyme in both human and mouse ovaries. The enzyme was localized in the theca interna, corpus luteum, granulosa cells, oocytes, and surface epithelium. Interestingly, haploinsufficiency of the HSD17B12 gene in female mice resulted in subfertility, indicating an important role for HSD17B12 enzyme in the ovarian function. In line with significantly increased length of the diestrous phase, the HSD17B+/- females gave birth less frequently than wild-type females, and the litter size of HSD17B12+/- females was significantly reduced. Interestingly, we observed meiotic spindle formation in immature follicles, suggesting defective meiotic arrest in HSD17B12+/- ovaries. The finding was further supported by transcriptome analysis showing differential expression of several genes related to the meiosis. In addition, polyovular follicles and oocytes trapped inside the corpus luteum were observed, indicating a failure in the oogenesis and ovulation, respectively. Intraovarian concentrations of steroid hormones were normal in HSD17B12+/- females, whereas the levels of AA and its metabolites (6-keto prostaglandin F1alpha, prostaglandin D2, prostaglandin E2, prostaglandin F2α, and thromboxane B2) were decreased. In conclusion, our study demonstrates that HSD17B12 enzyme plays an important role in female fertility through its role in AA metabolism.

  4. Novel mutations of HSD17B3 in three Chinese patients with 46,XY Disorders of Sex Development.

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    Yu, Bingqing; Liu, Zhaoxiang; Mao, Jiangfeng; Wang, Xi; Zheng, Junjie; Xiong, Shuyu; Cui, Mingxuan; Ma, Wanlu; Huang, Qibin; Xu, Hongli; Huang, Bingkun; Nie, Min; Wu, Xueyan

    2017-10-01

    17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) converts the inactive Δ4-androstenedione (A) to testosterone (T). Its deficiency is the most common testosterone biosynthesis defect that results in 46,XY Disorders Of Sex Development (DSD). However, the disease is difficult to distinguish from other 46,XY DSD for similar clinical phenotypes. Therefore, genetic testing provides good criteria for the diagnosis of the disease. In this study, HSD17B3 gene was examined in 3 unrelated Chinese patients with 46,XY DSD. Direct sequencing and quantitative PCR of HSD17B3 gene revealed the presence of a compound heterozygous mutation (p.I60T/exon1 deletion) in Patient 1, a homozygous (p.I60T) mutation in Patient 2 and a frameshift mutation (p.V25Efs∗54) and an exon1 deletion in Patient 3. All of the mutations have not been reported previously. These novel mutations may expand the mutation database of HSD17B3 gene and provide us new insights into the molecular mechanism of 17β-HSD3 deficiency. It is noteworthy that when direct sequence analysis showed a rare homozygous mutation in patients with non-consanguineous parents, "apparent homozygosity" should be taken into an account and the intragenic deletion should be screened. In addition, when single mutation was found in patients with disease in recessive heredity mode, the intragenic deletion should also be screened. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. PDGFRA, HSD17B4 and HMGB2 are potential therapeutic targets in polycystic ovarian syndrome and breast cancer

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    Xu, Huiyu; Han, Yong; Lou, Jiaying; Zhang, Hongxian; Zhao, Yue; Győrffy, Balázs; Li, Rong

    2017-01-01

    To explore the key genes associated with both PCOS and breast cancer, we overlapped the synchronously differently expressed genes in two obese insulin-resistant GEO datasets in muscle tissue and genes exert essential roles in breast cancer prognosis together base on the following reasons: (1) Androgens excess is believed to contribute to the onset of both PCOS and breast cancer. (2) PCOS is usually complicated with metabolic symptoms, such as obesity and insulin-resistance. (3) Muscle is the main place where energy metabolism and material metabolism take place. Consequently, 53 genes were found, functionally enriched in pathways such as pyruvate metabolism, muscle system process and development of primary male sexual characteristics etc. We further lay our eyes on genes correlated with male sexual characteristics, which may be involved in the onset of both PCOS and breast cancer. Three genes were indicated to be associated with this process, including hydroxysteroid (17-beta) dehydrogenase 4/HSD17B4, platelet-derived growth factor receptor, alpha polypeptide/PDGFRA and high-mobility group box 2/HMGB2. Gene-drug interaction network about the three genes were then constructed. Drugs or chemicals that contribute to correcting the disorder of lipid metabolism were detected to restore the abnormal expression of the three genes in PCOS, such as simvastatin, bezafibrate, fenofibrate et al, which provide further choices for managing patients with PCOS. PMID:29050221

  6. A novel mutation in the HSD17B10 gene of a 10-year-old boy with refractory epilepsy, choreoathetosis and learning disability.

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    Laurie H Seaver

    Full Text Available Hydroxysteroid (17beta dehydrogenase 10 (HSD10 is a mitochondrial multifunctional enzyme encoded by the HSD17B10 gene. Missense mutations in this gene result in HSD10 deficiency, whereas a silent mutation results in mental retardation, X-linked, syndromic 10 (MRXS10. Here we report a novel missense mutation found in the HSD17B10 gene, namely c.194T>C transition (rs104886492, brought about by the loss of two forked methyl groups of valine 65 in the HSD10 active site. The affected boy, who possesses mutant HSD10 (p.V65A, has a neurological syndrome with metabolic derangements, choreoathetosis, refractory epilepsy and learning disability. He has no history of acute decompensation or metabolic acidosis whereas his urine organic acid profile, showing elevated levels of 2-methyl-3-hydroxybutyrate and tiglylglycine, is characteristic of HSD10 deficiency. His HSD10 activity was much lower than the normal control level, with normal β-ketothiolase activity. The c.194T>C mutation in HSD17B10 can be identified by the restriction fragment polymorphism analysis, thereby facilitating the screening of this novel mutation in individuals with intellectual disability of unknown etiology and their family members much easier. The patient's mother is an asymptomatic carrier, and has a mixed ancestry (Hawaiian, Japanese and Chinese. This demonstrates that HSD10 deficiency patients are not confined to a particular ethnicity although previously reported cases were either Spanish or German descendants.

  7. A novel mutation in the HSD17B10 gene of a 10-year-old boy with refractory epilepsy, choreoathetosis and learning disability.

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    Seaver, Laurie H; He, Xue-Ying; Abe, Keith; Cowan, Tina; Enns, Gregory M; Sweetman, Lawrence; Philipp, Manfred; Lee, Sansan; Malik, Mazhar; Yang, Song-Yu

    2011-01-01

    Hydroxysteroid (17beta) dehydrogenase 10 (HSD10) is a mitochondrial multifunctional enzyme encoded by the HSD17B10 gene. Missense mutations in this gene result in HSD10 deficiency, whereas a silent mutation results in mental retardation, X-linked, syndromic 10 (MRXS10). Here we report a novel missense mutation found in the HSD17B10 gene, namely c.194T>C transition (rs104886492), brought about by the loss of two forked methyl groups of valine 65 in the HSD10 active site. The affected boy, who possesses mutant HSD10 (p.V65A), has a neurological syndrome with metabolic derangements, choreoathetosis, refractory epilepsy and learning disability. He has no history of acute decompensation or metabolic acidosis whereas his urine organic acid profile, showing elevated levels of 2-methyl-3-hydroxybutyrate and tiglylglycine, is characteristic of HSD10 deficiency. His HSD10 activity was much lower than the normal control level, with normal β-ketothiolase activity. The c.194T>C mutation in HSD17B10 can be identified by the restriction fragment polymorphism analysis, thereby facilitating the screening of this novel mutation in individuals with intellectual disability of unknown etiology and their family members much easier. The patient's mother is an asymptomatic carrier, and has a mixed ancestry (Hawaiian, Japanese and Chinese). This demonstrates that HSD10 deficiency patients are not confined to a particular ethnicity although previously reported cases were either Spanish or German descendants.

  8. Genetic Variants in HSD17B3, SMAD3, and IPO11 Impact Circulating Lipids in Response to Fenofibrate in Individuals With Type 2 Diabetes.

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    Rotroff, Daniel M; Pijut, Sonja S; Marvel, Skylar W; Jack, John R; Havener, Tammy M; Pujol, Aurora; Schluter, Agatha; Graf, Gregory A; Ginsberg, Henry N; Shah, Hetal S; Gao, He; Morieri, Mario-Luca; Doria, Alessandro; Mychaleckyi, Josyf C; McLeod, Howard L; Buse, John B; Wagner, Michael J; Motsinger-Reif, Alison A

    2017-07-24

    Individuals with type 2 diabetes (T2D) and dyslipidemia are at an increased risk of cardiovascular disease. Fibrates are a class of drugs prescribed to treat dyslipidemia, but variation in response has been observed. To evaluate common and rare genetic variants that impact lipid responses to fenofibrate in statin-treated patients with T2D, we examined lipid changes in response to fenofibrate therapy using a genomewide association study (GWAS). Associations were followed-up using gene expression studies in mice. Common variants in SMAD3 and IPO11 were marginally associated with lipid changes in black subjects (P < 5 × 10-6 ). Rare variant and gene expression changes were assessed using a false discovery rate approach. AKR7A3 and HSD17B13 were associated with lipid changes in white subjects (q < 0.2). Mice fed fenofibrate displayed reductions in Hsd17b13 gene expression (q < 0.1). Associations of variants in SMAD3, IPO11, and HSD17B13, with gene expression changes in mice indicate that transforming growth factor-beta (TGF-β) and NRF2 signaling pathways may influence fenofibrate effects on dyslipidemia in patients with T2D. © 2017, The American Society for Clinical Pharmacology and Therapeutics.

  9. Polymorphisms in HSD17B1: Early Onset and Increased Risk of Alzheimer’s Disease in Women with Down Syndrome

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    Joseph H. Lee

    2012-01-01

    Full Text Available Background/Aims. Genetic variants that affect estrogen activity may influence the risk of Alzheimer's disease (AD. In women with Down syndrome, we examined the relation of polymorphisms in hydroxysteroid-17beta-dehydrogenase (HSD17B1 to age at onset and risk of AD. HSD17B1 encodes the enzyme 17β-hydroxysteroid dehydrogenase (HSD1, which catalyzes the conversion of estrone to estradiol. Methods. Two hundred and thirty-eight women with DS, nondemented at baseline, 31–78 years of age, were followed at 14–18-month intervals for 4.5 years. Women were genotyped for 5 haplotype-tagging single-nucleotide polymorphisms (SNPs in the HSD17B1 gene region, and their association with incident AD was examined. Results. Age at onset was earlier, and risk of AD was elevated from two- to threefold among women homozygous for the minor allele at 3 SNPs in intron 4 (rs676387, exon 6 (rs605059, and exon 4 in COASY (rs598126. Carriers of the haplotype TCC, based on the risk alleles for these three SNPs, had an almost twofold increased risk of developing AD (hazard ratio = 1.8, 95% CI, 1.1–3.1. Conclusion. These findings support experimental and clinical studies of the neuroprotective role of estrogen.

  10. Dioxin exposure reduces the steroidogenic capacity of mouse antral follicles mainly at the level of HSD17B1 without altering atresia

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    Karman, Bethany N., E-mail: bklement@illinois.edu; Basavarajappa, Mallikarjuna S., E-mail: mbshivapur@gmail.com; Hannon, Patrick, E-mail: phannon2@illinois.edu; Flaws, Jodi A., E-mail: jflaws@illinois.edu

    2012-10-01

    2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent ovarian toxicant. Previously, we demonstrated that in vitro TCDD (1 nM) exposure decreases production/secretion of the sex steroid hormones progesterone (P4), androstenedione (A4), testosterone (T), and 17β-estradiol (E2) in mouse antral follicles. The purpose of this study was to determine the mechanism by which TCDD inhibits steroidogenesis. Specifically, we examined the effects of TCDD on the steroidogenic enzymes, atresia, and the aryl hydrocarbon receptor (AHR) protein. TCDD exposure for 48 h increased levels of A4, without changing HSD3B1 protein, HSD17B1 protein, estrone (E1), T or E2 levels. Further, TCDD did not alter atresia ratings compared to vehicle at 48 h. TCDD, however, did down regulate the AHR protein at 48 h. TCDD exposure for 96 h decreased transcript levels for Cyp11a1, Cyp17a1, Hsd17b1, and Cyp19a1, but increased Hsd3b1 transcript. TCDD exposure particularly lowered both Hsd17b1 transcript and HSD17B1 protein. However, TCDD exposure did not affect levels of E1 in the media nor atresia ratings at 96 h. TCDD, however, decreased levels of the proapoptotic factor Bax. Collectively, these data suggest that TCDD exposure causes a major block in the steroidogenic enzyme conversion of A4 to T and E1 to E2 and that it regulates apoptotic pathways, favoring survival over death in antral follicles. Finally, the down‐regulation of the AHR protein in TCDD exposed follicles persisted at 96 h, indicating that the activation and proteasomal degradation of this receptor likely plays a central role in the impaired steroidogenic capacity and altered apoptotic pathway of exposed antral follicles. -- Highlights: ► TCDD disrupts steroidogenic enzymes in mouse antral follicles. ► TCDD particularly affects the HSD17B1 enzyme in mouse antral follicles. ► TCDD does not affect atresia ratings in mouse antral follicles. ► TCDD decreases levels of the proapoptitic factor Bax in mouse antral follicles.

  11. Biochemical Analysis of Four Missense Mutations in the HSD17B3 Gene Associated With 46,XY Disorders of Sex Development in Egyptian Patients.

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    Engeli, Roger T; Tsachaki, Maria; Hassan, Heba A; Sager, Christoph P; Essawi, Mona L; Gad, Yehia Z; Kamel, Alaa K; Mazen, Inas; Odermatt, Alex

    2017-09-01

    Mutations in the HSD17B3 gene are associated with a 46,XY disorder of sexual development (46,XY DSD) as a result of low testosterone production during embryogenesis. To elucidate the molecular basis of the disorder by chemically analyzing four missense mutations in HSD17B3 (T54A, M164T, L194P, G289S) from Egyptian patients with 46,XY DSD. Expression plasmids for wild-type 17β-hydroxysteroid hydrogenase type 3 (17β-HSD3) and mutant enzymes generated by site-directed mutagenesis were transiently transfected into human HEK-293 cells. Protein expression was verified by western blotting and activity was determined by measuring the conversion of radiolabeled Δ4-androstene-3,17-dione to testosterone. Application of a homology model provided an explanation for the observed effects of the mutations. Testosterone formation by wild-type and mutant 17β-HSD3 enzymes was compared. Mutations T54A and L194P, despite normal protein expression, completely abolished 17β-HSD3 activity, explaining their severe 46,XY DSD phenotype. Mutant M164T could still produce testosterone, albeit with significantly lower activity compared with wild-type 17β-HSD3, resulting in ambiguous genitalia or a microphallus at birth. The substitution G289S represented a polymorphism exhibiting comparable activity to wild-type 17β-HSD3. Sequencing of the SRD5A2 gene in three siblings bearing the HSD17B3 G289S polymorphism disclosed the homozygous Y91H mutation in the former gene, thus explaining the 46,XY DSD presentations. Molecular modeling analyses supported the biochemical observations and predicted a disruption of cofactor binding by mutations T54A and M164T and of substrate binding by L196P, resulting in the loss of enzyme activity. In contrast, the G289S substitution was predicted to disturb neither the three-dimensional structure nor enzyme activity. Biochemical analysis of mutant 17β-HSD3 enzymes is necessary to understand genotype-phenotype relationships. Biochemical analysis combined with

  12. Specific combination of compound heterozygous mutations in 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4 defines a new subtype of D-bifunctional protein deficiency

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    McMillan Hugh J

    2012-11-01

    Full Text Available Abstract Background D-bifunctional protein (DBP deficiency is typically apparent within the first month of life with most infants demonstrating hypotonia, psychomotor delay and seizures. Few children survive beyond two years of age. Among patients with prolonged survival all demonstrate severe gross motor delay, absent language development, and severe hearing and visual impairment. DBP contains three catalytically active domains; an N-terminal dehydrogenase, a central hydratase and a C-terminal sterol carrier protein-2-like domain. Three subtypes of the disease are identified based upon the domain affected; DBP type I results from a combined deficiency of dehydrogenase and hydratase activity; DBP type II from isolated hydratase deficiency and DBP type III from isolated dehydrogenase deficiency. Here we report two brothers (16½ and 14 years old with DBP deficiency characterized by normal early childhood followed by sensorineural hearing loss, progressive cerebellar and sensory ataxia and subclinical retinitis pigmentosa. Methods and results Biochemical analysis revealed normal levels of plasma VLCFA, phytanic acid and pristanic acid, and normal bile acids in urine; based on these results no diagnosis was made. Exome analysis was performed using the Agilent SureSelect 50Mb All Exon Kit and the Illumina HiSeq 2000 next-generation-sequencing (NGS platform. Compound heterozygous mutations were identified by exome sequencing and confirmed by Sanger sequencing within the dehydrogenase domain (c.101C>T; p.Ala34Val and hydratase domain (c.1547T>C; p.Ile516Thr of the 17β-hydroxysteroid dehydrogenase type 4 gene (HSD17B4. These mutations have been previously reported in patients with severe-forms of DBP deficiency, however each mutation was reported in combination with another mutation affecting the same domain. Subsequent studies in fibroblasts revealed normal VLCFA levels, normal C26:0 but reduced pristanic acid beta-oxidation activity. Both DBP

  13. Genetic Basis of the Relationship Between Reproduction and Longevity: A Study on Common Variants of Three Genes in Steroid Hormone Metabolism--CYP17, HSD17B1, and COMT.

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    Scarabino, Daniela; Scacchi, Renato; Pinto, Alessandro; Corbo, Rosa Maria

    2015-10-01

    Evolutionary theories of aging predict an antagonistic relationship between fertility and life span in humans, but the genetic basis of this phenomenon is not clear. The variation of three genes in steroid hormone metabolism--CYP17 (rs743572), HSD17B1 (rs 605059), and COMT (rs4680)--was examined to elucidate the genetic basis of the relationship between fertility and life span. A sample of 277 individuals (mean age, 82.9 years) was recruited in 2000. On the basis of mortality data collected in 2009, the sample was divided into two groups of subjects surviving to over 90 years (long-lived) or not (controls). Fertility data (number of children) were collected in the same sample. The HSD17B1 AA genotype was found to be significantly associated (p = 0.0085) with longevity only in the females (estimated odds ratio = 3.77). Because the HSD17B1 AA genotype was also associated with a higher number of children (5.3 ± 2.1) than the other genotypes (p = 0.006), we may infer that HSD17B1 genotypes could exert a positive pleiotropic action on longevity and fertility. CYP17 and COMT gene variation did not influence either life span or fertility. We then searched the literature for genes studied in relation to both reproduction and aging. A review of the studies showed a pleiotropic action for six out of 16 genes and revealed that genes may exert positive, or negative, or antagonistic pleiotropic actions. These potential actions may be modified by such environmental factors such as changing reproductive behaviors, which seem to be able to mitigate or enhance a gene's phenotypic effects.

  14. Topological similarity between the 2μm plasmid partitioning locus and the budding yeast centromere: evidence for a common evolutionary origin?

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    Jayaram, Makkuni; Chang, Keng-Ming; Ma, Chien-Hui; Huang, Chu-Chun; Liu, Yen-Ting; Sau, Soumitra

    2013-04-01

    The partitioning locus STB of the selfish plasmid, the 2μm circle, of Saccharomyces cerevisiae is essential for the propagation of this multi-copy extra-chromosomal DNA element with nearly chromosome-like stability. The functional competence of STB requires the plasmid-coded partitioning proteins Rep1 and Rep2 as well as host-coded proteins. Host factors that associate with STB in a Rep1- and Rep2-dependent manner also interact with centromeres, and play important roles in chromosome segregation. They include the cohesin complex and the centromere-specific histone H3 variant Cse4. The genetically defined point centromere of S. cerevisiae differs starkly from the much more widespread epigenetically specified regional centromeres of eukaryotes. The particularly small size of the S. cerevisiae centromere and the association of chromosome segregation factors with STB raise the possibility of an evolutionary link between these two partitioning loci. The unusual positive supercoiling harboured by the S. cerevisiae centromere and STB in vivo in their functional states, unveiled by recent experiments, bolsters the notion of their potential descent from an ancestral plasmid partitioning locus.

  15. The Finnish lapphund retinal atrophy locus maps to the centromeric region of CFA9

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    Sargan David R

    2007-07-01

    Full Text Available Abstract Background Dogs have the second largest number of genetic diseases, after humans. Among the diseases present in dogs, progressive retinal atrophy has been reported in more than a hundred breeds. In some of them, the mutation has been identified and genetic tests have allowed the identification of carriers, thus enabling a drastic reduction in the incidence of the disease. The Finnish lapphund is a dog breed presenting late-onset progressive retinal atrophy for which the disease locus remains unknown. Results In this study we mapped the progressive retinal atrophy locus in the Finnish lapphund using a DNA pooling approach, assuming that all affected dogs within the breed share the same identical-by descent-mutation as the cause of the disease (genetic homogeneity. Autosomal recessive inheritance was also assumed, after ruling out, from pedigree analysis, dominant and X-linked inheritance. DNA from 12 Finnish lapphund cases was mixed in one pool, and DNA from 12 first-degree relatives of these cases was mixed to serve as the control pool. The 2 pools were tested with 133 microsatellite markers, 3 of which showed a shift towards homozygosity in the cases. Individual genotyping with these 3 markers confirmed homozygosity for the GALK1 microsatellite only (chromosome 9. Further individual genotyping with additional samples (4 cases and 59 controls confirmed the association between this marker and the disease locus (p Conclusion The locus for progressive rod-cone degeneration is known to be close to the GALK1 locus, on the telomeric region of chromosome 9, where the retinal atrophy locus of the Finnish lapphund has been mapped. This suggests that the disease in this breed, as well as in the Swedish lapphund, may correspond to progressive rod-cone degeneration. This would increase the number of known dog breeds having this particular form of progressive retinal atrophy.

  16. Actin-binding protein (ABP-280) filamin gene (FLN) maps telomeric to the color vision locus (R/GCP) and centromeric to G6PD in Xq28

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    Gorlin, J.B. (Brigham and Women' s Hospital, Boston, MA (United States) Dana-Farber Cancer Institute, Boston, MA (United States)); Henske, E.; Hartwig, J.H.; Kwiatkowski, D.J. (Brigham and Women' s Hospital, Boston, MA (United States)); Warren, S.T.; Kunst, C.B. (Emory Univ. School of Medicine, Atlanta, GA (United States)); D' Urso, M.; Palmieri, G. (International Institute of Genetics and Biophysics, Naples, (Italy)); Bruns, G. (Children' s Hospital, Boston, MA (United States))

    1993-08-01

    Actin-binding protein-280 (ABP-280) is a dimeric actin filament-crosslinking protein that promotes orthogonal branching of actin filaments and links actin filaments to membrane glycoproteins. The authors have mapped the ABP-280 filamin gene (FLN) to Xq28 by Southern blot analysis of somatic cell hybrid lines, by fluorescence in situ hybridization, and through identification of portions of the FLN gene within cosmids and YACs mapped to Xq28. The FLN gene is found within a 200-kb region centromeric to the G6PD locus and telomeric to DSX52 and the color vision locus. 23 refs., 2 figs.

  17. The evolutionary life cycle of the resilient centromere.

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    Kalitsis, Paul; Choo, K H Andy

    2012-08-01

    The centromere is a chromosomal structure that is essential for the accurate segregation of replicated eukaryotic chromosomes to daughter cells. In most centromeres, the underlying DNA is principally made up of repetitive DNA elements, such as tandemly repeated satellite DNA and retrotransposable elements. Paradoxically, for such an essential genomic region, the DNA is rapidly evolving both within and between species. In this review, we show that the centromere locus is a resilient structure that can undergo evolutionary cycles of birth, growth, maturity, death and resurrection. The birth phase is highlighted by examples in humans and other organisms where centromere DNA deletions or chromosome rearrangements can trigger the epigenetic assembly of neocentromeres onto genomic sites without typical features of centromere DNA. In addition, functional centromeres can be generated in the laboratory using various methodologies. Recent mapping of the foundation centromere mark, the histone H3 variant CENP-A, onto near-complete genomes has uncovered examples of new centromeres which have not accumulated centromere repeat DNA. During the growth period of the centromere, repeat DNA begins to appear at some, but not all, loci. The maturity stage is characterised by centromere repeat accumulation, expansions and contractions and the rapid evolution of the centromere DNA between chromosomes of the same species and between species. This stage provides inherent centromere stability, facilitated by repression of gene activity and meiotic recombination at and around the centromeres. Death to a centromere can result from genomic instability precipitating rearrangements, deletions, accumulation of mutations and the loss of essential centromere binding proteins. Surprisingly, ancestral centromeres can undergo resurrection either in the field or in the laboratory, via as yet poorly understood mechanisms. The underlying principle for the preservation of a centromeric evolutionary life

  18. Centromere repositioning in mammals

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    Rocchi, M; Archidiacono, N; Schempp, W; Capozzi, O; Stanyon, R

    2011-01-01

    The evolutionary history of chromosomes can be tracked by the comparative hybridization of large panels of bacterial artificial chromosome clones. This approach has disclosed an unprecedented phenomenon: ‘centromere repositioning', that is, the movement of the centromere along the chromosome without marker order variation. The occurrence of evolutionary new centromeres (ENCs) is relatively frequent. In macaque, for instance, 9 out of 20 autosomal centromeres are evolutionarily new; in donkey ...

  19. The Past, Present, and Future of Human Centromere Genomics

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    Megan E. Aldrup-MacDonald

    2014-01-01

    Full Text Available The centromere is the chromosomal locus essential for chromosome inheritance and genome stability. Human centromeres are located at repetitive alpha satellite DNA arrays that compose approximately 5% of the genome. Contiguous alpha satellite DNA sequence is absent from the assembled reference genome, limiting current understanding of centromere organization and function. Here, we review the progress in centromere genomics spanning the discovery of the sequence to its molecular characterization and the work done during the Human Genome Project era to elucidate alpha satellite structure and sequence variation. We discuss exciting recent advances in alpha satellite sequence assembly that have provided important insight into the abundance and complex organization of this sequence on human chromosomes. In light of these new findings, we offer perspectives for future studies of human centromere assembly and function.

  20. Centromeres of filamentous fungi

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    Smith, Kristina M.; Galazka, Jonathan M.; Phatale, Pallavi A.; Connolly, Lanelle R.; Freitag, Michael

    2012-01-01

    How centromeres are assembled and maintained remains one of the fundamental questions in cell biology. Over the past 20 years the idea of centromeres as precise genetic loci has been replaced by the realization that it is predominantly the protein complement that defines centromere localization and function. Thus, placement and maintenance of centromeres are excellent examples of epigenetic phenomena in the strict sense. In contrast, the highly derived “point centromeres” of the budding yeast Saccharomyces cerevisiae and its close relatives are counterexamples for this general principle of centromere maintenance. While we have learned much in the past decade, it remains unclear if mechanisms for epigenetic centromere placement and maintenance are shared amongst various groups of organisms. For that reason it seems prudent to examine species from many different phylogenetic groups with the aim to extract comparative information that will yield a more complete picture of cell division in all eukaryotes. This review addresses what has been learned by studying the centromeres of filamentous fungi, a large, heterogeneous group of organisms that includes important plant, animal and human pathogens, saprobes and symbionts that fulfill essential roles in the biosphere, as well as a growing number of taxa that have become indispensable for industrial use. PMID:22752455

  1. Centromere repositioning in mammals.

    Science.gov (United States)

    Rocchi, M; Archidiacono, N; Schempp, W; Capozzi, O; Stanyon, R

    2012-01-01

    The evolutionary history of chromosomes can be tracked by the comparative hybridization of large panels of bacterial artificial chromosome clones. This approach has disclosed an unprecedented phenomenon: 'centromere repositioning', that is, the movement of the centromere along the chromosome without marker order variation. The occurrence of evolutionary new centromeres (ENCs) is relatively frequent. In macaque, for instance, 9 out of 20 autosomal centromeres are evolutionarily new; in donkey at least 5 such neocentromeres originated after divergence from the zebra, in less than 1 million years. Recently, orangutan chromosome 9, considered to be heterozygous for a complex rearrangement, was discovered to be an ENC. In humans, in addition to neocentromeres that arise in acentric fragments and result in clinical phenotypes, 8 centromere-repositioning events have been reported. These 'real-time' repositioned centromere-seeding events provide clues to ENC birth and progression. In the present paper, we provide a review of the centromere repositioning. We add new data on the population genetics of the ENC of the orangutan, and describe for the first time an ENC on the X chromosome of squirrel monkeys. Next-generation sequencing technologies have started an unprecedented, flourishing period of rapid whole-genome sequencing. In this context, it is worth noting that these technologies, uncoupled from cytogenetics, would miss all the biological data on evolutionary centromere repositioning. Therefore, we can anticipate that classical and molecular cytogenetics will continue to have a crucial role in the identification of centromere movements. Indeed, all ENCs and human neocentromeres were found following classical and molecular cytogenetic investigations.

  2. Centromere Emergence in Evolution

    OpenAIRE

    Ventura, Mario; Archidiacono, Nicoletta; Rocchi, Mariano

    2001-01-01

    Evolutionary centromere repositioning is a paradox we have recently discovered while studying the conservation of the phylogenetic chromosome IX in primates. Two explanations were proposed: a conservative hypothesis assuming sequential pericentric inversions, and a more challenging assumption involving centromere emergence during evolution. The complex evolutionary history showed by chromosome IX did not allow us to clearly distinguish between these two hypotheses. Here we report comparative ...

  3. Chromosome Y centromere array deletion leads to impaired centromere function.

    Directory of Open Access Journals (Sweden)

    Alison N Graham

    Full Text Available The centromere is an essential chromosomal structure that is required for the faithful distribution of replicated chromosomes to daughter cells. Defects in the centromere can compromise the stability of chromosomes resulting in segregation errors. We have characterised the centromeric structure of the spontaneous mutant mouse strain, BALB/cWt, which exhibits a high rate of Y chromosome instability. The Y centromere DNA array shows a de novo interstitial deletion and a reduction in the level of the foundation centromere protein, CENP-A, when compared to the non-deleted centromere array in the progenitor strain. These results suggest there is a lower threshold limit of centromere size that ensures full kinetochore function during cell division.

  4. Dynamic epigenetic states of maize centromeres

    Directory of Open Access Journals (Sweden)

    Yalin eLiu

    2015-10-01

    Full Text Available The centromere is a specialized chromosomal region identified as the major constriction, upon which the kinetochore complex is formed, ensuring accurate chromosome orientation and segregation during cell division. The rapid evolution of centromere DNA sequence and the conserved centromere function are two contradictory aspects of centromere biology. Indeed, the sole presence of genetic sequence is not sufficient for centromere formation. Various dicentric chromosomes with one inactive centromere have been recognized. It has also been found that de novo centromere formation is common on fragments in which centromeric DNA sequences are lost. Epigenetic factors play important roles in centromeric chromatin assembly and maintenance. Nondisjunction of the supernumerary B chromosome early prophase of meiosis I requires an active centromere. This review discusses recent studies in maize about genetic and epigenetic elements regulating formation and maintenance of centromere chromatin, as well as centromere behavior in meiosis.

  5. PDGFRA, HSD17B4 and HMGB2 are potential therapeutic targets in polycystic ovarian syndrome and breast cancer

    OpenAIRE

    Xu, Huiyu; Han, Yong; Lou, Jiaying; Zhang, Hongxian; Zhao, Yue; Győrffy, Balázs; Li, Rong

    2017-01-01

    To explore the key genes associated with both PCOS and breast cancer, we overlapped the synchronously differently expressed genes in two obese insulin-resistant GEO datasets in muscle tissue and genes exert essential roles in breast cancer prognosis together base on the following reasons: (1) Androgens excess is believed to contribute to the onset of both PCOS and breast cancer. (2) PCOS is usually complicated with metabolic symptoms, such as obesity and insulin-resistance. (3) Muscle is the ...

  6. Centromere Stability: The Replication Connection

    Directory of Open Access Journals (Sweden)

    Susan L. Forsburg

    2017-01-01

    Full Text Available The fission yeast centromere, which is similar to metazoan centromeres, contains highly repetitive pericentromere sequences that are assembled into heterochromatin. This is required for the recruitment of cohesin and proper chromosome segregation. Surprisingly, the pericentromere replicates early in the S phase. Loss of heterochromatin causes this domain to become very sensitive to replication fork defects, leading to gross chromosome rearrangements. This review examines the interplay between components of DNA replication, heterochromatin assembly, and cohesin dynamics that ensures maintenance of genome stability and proper chromosome segregation.

  7. A PSHaver for centromeric histones.

    Science.gov (United States)

    Folco, H Diego; Desai, Arshad

    2010-11-12

    In this issue of Molecular Cell, Hewawasam et al. (2010) and Ranjitkar et al. (2010) identify and characterize Psh1, an E3 ubiquitin ligase that specifically targets the centromeric histone Cse4 in budding yeast and limits its misincorporation at noncentromeric regions. Copyright © 2010 Elsevier Inc. All rights reserved.

  8. Centromere domain organization and histone modifications

    Directory of Open Access Journals (Sweden)

    P. Bjerling

    2002-05-01

    Full Text Available Centromere function requires the proper coordination of several subfunctions, such as kinetochore assembly, sister chromatid cohesion, binding of kinetochore microtubules, orientation of sister kinetochores to opposite spindle poles, and their movement towards the spindle poles. Centromere structure appears to be organized in different, separable domains in order to accomplish these functions. Despite the conserved nature of centromere functions, the molecular genetic definition of the DNA sequences that form a centromere in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, in the fruit fly Drosophila melanogaster, and in humans has revealed little conservation at the level of centromere DNA sequences. Also at the protein level few centromere proteins are conserved in all of these four organisms and many are unique to the different organisms. The recent analysis of the centromere structure in the yeast S. pombe by electron microscopy and detailed immunofluorescence microscopy of Drosophila centromeres have brought to light striking similarities at the overall structural level between these centromeres and the human centromere. The structural organization of the centromere is generally multilayered with a heterochromatin domain and a central core/inner plate region, which harbors the outer plate structures of the kinetochore. It is becoming increasingly clear that the key factors for assembly and function of the centromere structure are the specialized histones and modified histones which are present in the centromeric heterochromatin and in the chromatin of the central core. Thus, despite the differences in the DNA sequences and the proteins that define a centromere, there is an overall structural similarity between centromeres in evolutionarily diverse eukaryotes.

  9. Structure, Function, and Evolution of Rice Centromeres

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jiming

    2010-02-04

    The centromere is the most characteristic landmark of eukaryotic chromosomes. Centromeres function as the site for kinetochore assembly and spindle attachment, allowing for the faithful pairing and segregation of sister chromatids during cell division. Characterization of centromeric DNA is not only essential to understand the structure and organization of plant genomes, but it is also a critical step in the development of plant artificial chromosomes. The centromeres of most model eukaryotic species, consist predominantly of long arrays of satellite DNA. Determining the precise DNA boundary of a centromere has proven to be a difficult task in multicellular eukaryotes. We have successfully cloned and sequenced the centromere of rice chromosome 8 (Cen8), representing the first fully sequenced centromere from any multicellular eukaryotes. The functional core of Cen8 spans ~800 kb of DNA, which was determined by chromatin immunoprecipitation (ChIP) using an antibody against the rice centromere-specific H3 histone. We discovered 16 actively transcribed genes distributed throughout the Cen8 region. In addition to Cen8, we have characterized eight additional rice centromeres using the next generation sequencing technology. We discovered four subfamilies of the CRR retrotransposon that is highly enriched in rice centromeres. CRR elements are constitutively transcribed and different CRR subfamilies are differentially processed by RNAi. These results suggest that different CRR subfamilies may play different roles in the RNAi-mediated pathway for formation and maintenance of centromeric chromatin.

  10. Molecular characterization of flow-sorted mammalian centromeres

    Energy Technology Data Exchange (ETDEWEB)

    Hamkalo, B.A.; Henschen, A.; Parseghian, M.H. [Univ. of Calfornia, Irvine, CA (United States). Dept. of Molecular Biology and Biochemistry] [and others

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project involved experiments directed towards developing a molecular characterization of the centromere region of mammalian chromosomes. Attempts to purify this essential chromosomal locus by conventional methods have thus far been unsuccessful. However, preliminary data obtained in collaboration with the National Flow Cytometry Resource (NFCR) showed that it is possible to purify a chromosome fragment that is present in certain cultured mouse cell lines and has all the properties expected of an intact centromere region. To begin sorting this minichromosome for the identification of proteins preferentially associated with centromere regions, standard buffers utilized in chromosome sorting were evaluated for potential effects on maintenance of chromosomal proteins during sorting. The data indicate that the presence of several buffer constituents results in the extraction of all but a few chromosomal proteins. The subsequent use of a magnesium sulfate buffer resulted in the sorting of mouse chromosomes that do not suffer a significant loss of proteins. Several DNA stains were also evaluated for causing protein dissociation, but no significant losses were observed. Although flow-sorted chromosomes have been used extensively for DNA analysis and cloning, this is a pioneering effort by the NFCR, and its collaborators, to exploit chromosome sorting capabilities for the analysis of chromosomal proteins.

  11. Discovery of an unconventional centromere in budding yeast redefines evolution of point centromeres.

    Science.gov (United States)

    Kobayashi, Norihiko; Suzuki, Yutaka; Schoenfeld, Lori W; Müller, Carolin A; Nieduszynski, Conrad; Wolfe, Kenneth H; Tanaka, Tomoyuki U

    2015-08-03

    Centromeres are the chromosomal regions promoting kinetochore assembly for chromosome segregation. In many eukaryotes, the centromere consists of up to mega base pairs of DNA. On such "regional centromeres," kinetochore assembly is mainly defined by epigenetic regulation [1]. By contrast, a clade of budding yeasts (Saccharomycetaceae) has a "point centromere" of 120-200 base pairs of DNA, on which kinetochore assembly is defined by the consensus DNA sequence [2, 3]. During evolution, budding yeasts acquired point centromeres, which replaced ancestral, regional centromeres [4]. All known point centromeres among different yeast species share common consensus DNA elements (CDEs) [5, 6], implying that they evolved only once and stayed essentially unchanged throughout evolution. Here, we identify a yeast centromere that challenges this view: that of the budding yeast Naumovozyma castellii is the first unconventional point centromere with unique CDEs. The N. castellii centromere CDEs are essential for centromere function but have different DNA sequences from CDEs in other point centromeres. Gene order analyses around N. castellii centromeres indicate their unique, and separate, evolutionary origin. Nevertheless, they are still bound by the ortholog of the CBF3 complex, which recognizes CDEs in other point centromeres. The new type of point centromere originated prior to the divergence between N. castellii and its close relative Naumovozyma dairenensis and disseminated to all N. castellii chromosomes through extensive genome rearrangement. Thus, contrary to the conventional view, point centromeres can undergo rapid evolutionary changes. These findings give new insights into the evolution of point centromeres. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Synaptonemal complex components persist at centromeres and are required for homologous centromere pairing in mouse spermatocytes.

    Directory of Open Access Journals (Sweden)

    C Gaston Bisig

    2012-06-01

    Full Text Available Recent studies in simple model organisms have shown that centromere pairing is important for ensuring high-fidelity meiotic chromosome segregation. However, this process and the mechanisms regulating it in higher eukaryotes are unknown. Here we present the first detailed study of meiotic centromere pairing in mouse spermatogenesis and link it with key events of the G2/metaphase I transition. In mouse we observed no evidence of the persistent coupling of centromeres that has been observed in several model organisms. We do however find that telomeres associate in non-homologous pairs or small groups in B type spermatogonia and pre-leptotene spermatocytes, and this association is disrupted by deletion of the synaptonemal complex component SYCP3. Intriguingly, we found that, in mid prophase, chromosome synapsis is not initiated at centromeres, and centromeric regions are the last to pair in the zygotene-pachytene transition. In late prophase, we first identified the proteins that reside at paired centromeres. We found that components of the central and lateral element and transverse filaments of the synaptonemal complex are retained at paired centromeres after disassembly of the synaptonemal complex along diplotene chromosome arms. The absence of SYCP1 prevents centromere pairing in knockout mouse spermatocytes. The localization dynamics of SYCP1 and SYCP3 suggest that they play different roles in promoting homologous centromere pairing. SYCP1 remains only at paired centromeres coincident with the time at which some kinetochore proteins begin loading at centromeres, consistent with a role in assembly of meiosis-specific kinetochores. After removal of SYCP1 from centromeres, SYCP3 then accumulates at paired centromeres where it may promote bi-orientation of homologous centromeres. We propose that, in addition to their roles as synaptonemal complex components, SYCP1 and SYCP3 act at the centromeres to promote the establishment and/or maintenance of

  13. Centromere organization in man and mouse

    Energy Technology Data Exchange (ETDEWEB)

    Jeppesen, P.; Mitchell, A.; Kipling, D.; Nicol, L. [Western General Hospital, Edinburgh (United Kingdom)

    1993-12-31

    The kinetochore, located at the primary constriction or centromere in mammalian metaphase chromosomes, is the site of attachment of spindle microtubules to the mitotic chromosome, and is thus essential for correct chromosome movement and segregation at anaphase. Errors in organization of the kinetochore and/or centromere may therefore lead to non-disjunction and aneuploidy. The centromeres of most, if not all, mammalian chromosomes contain repetitive DNA sequences, which are observed at the cytogenetic level as heterochromatin. We have combined immunofluorescence with primed in situ hybridization (PRINS) techniques to study the organization of repetitive DNA families in relation to chromosomal proteins located at centromeres in both man and mouse species.

  14. Insights into centromeric transcription in mitosis.

    Science.gov (United States)

    Liu, Hong

    2016-01-01

    The major role of RNA polymerase II (RNAP II) is to generate mRNAs. I recently uncovered a novel function of RNAP II in chromosome segregation in mitosis, installing the cohesin protector, Shugoshin, at centromeres. Here I will discuss the current understanding of RNAP II-dependent centromeric transcription in mitosis.

  15. Epigenetic aspects of centromere function in plants.

    Science.gov (United States)

    Birchler, James A; Gao, Zhi; Sharma, Anupma; Presting, Gernot G; Han, Fangpu

    2011-04-01

    Centromeres were once thought to be boring structures on the chromosome involved with transmission through mitosis and meiosis. Recent data from a wide spectrum of organisms reveal an epigenetic component to centromere specification in that they can become inactive easily or form over unique DNA as neocentromeres. However, the constancy of centromere repeats at primary constrictions in most species, the fact that these repeats are transcribed and incorporated into the kinetochore, and the phenomenon of reactivation of formerly inactive centromeres at the same chromosomal sites suggests some type of role of DNA sequence or configuration in establishing the site of kinetochores. Here we present evidence for epigenetic and structural aspects involved with centromere activity in plants. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Sunflower centromeres consist of a centromere-specific LINE and a chromosome-specific tandem repeat

    Directory of Open Access Journals (Sweden)

    Kiyotaka eNagaki

    2015-10-01

    Full Text Available The kinetochore is a protein complex including kinetochore-specific proteins that plays a role in chromatid segregation during mitosis and meiosis. The complex associates with centromeric DNA sequences that are usually species-specific. In plant species, tandem repeats including satellite DNA sequences and retrotransposons have been reported as centromeric DNA sequences. In this study on sunflowers, a cDNA-encoding centromere-specific histone H3 (CENH3 was isolated from a cDNA pool from a seedling, and an antibody was raised against a peptide synthesized from the deduced cDNA. The antibody specifically recognized the sunflower CENH3 (HaCENH3 and showed centromeric signals by immunostaining and immunohistochemical staining analysis. The antibody was also applied in chromatin immunoprecipitation (ChIP-Seq to isolate centromeric DNA sequences and two different types of repetitive DNA sequences were identified. One was a long interspersed nuclear element (LINE-like sequence, which showed centromere-specific signals on almost all chromosomes in sunflowers. This is the first report of a centromeric LINE sequence, suggesting possible centromere targeting ability. Another type of identified repetitive DNA was a tandem repeat sequence with a 187-bp unit that was found only on a pair of chromosomes. The HaCENH3 content of the tandem repeats was estimated to be much higher than that of the LINE, which implies centromere evolution from LINE-based centromeres to more stable tandem-repeat-based centromeres. In addition, the epigenetic status of the sunflower centromeres was investigated by immunohistochemical staining and ChIP, and it was found that centromeres were heterochromatic.

  17. Analysis of a human mutant centromere: Key to the identification of essential centromeric sequences

    Energy Technology Data Exchange (ETDEWEB)

    Darfler, M. [Life Technologies, Inc., Gaithersburg, MD (United States); Magnani, I.; Fuhman-Conti, A. [Univ. of Milan (Italy)

    1994-09-01

    Three elements are required for replication and segregation in human chromosomes. Of these, human telomere and origin of replication sequences have already been identified. The essential centromeric sequences necessary and sufficient for segregation are not yet known. To this end the molecular analysis of rare human centromere mutants may be extremely important. Chromosomes with atypical centromeres may be found in human karyotypes and can be used for studies of the molecular organization of the human centromere. We are currently studying the centromere of a stable, apparently acentric, marker chromosome. By using chromosme painting we established that the marker chromosome was derived from the distal region of chromosome 14. In situ hybridization analysis of this minichromosome did not show evidence of alpha satellite sequences which are present in all human centromeres or beta satellite DNA also found in many human chromosomes. CREST autoimmune sera, known to recognize the CENP-B centromeric protein, highlighted the marker`s kinetochore. This finding strongly indicated the presence in the marker chromosome of DNA sequences essential for segregation. Despite its origin, the marker was negative for 14/22 centromere-specific alphoid DNA. In an attempt to identify the origin of the marker centromeric sequences we amplified the flow sorted marker chromosome by degenerate oligonucleotide-primed-polymerase chain reaction (DOP-PCR). Probes generated under different conditions highlighted either the 14q32-qter region, the pericentromeric region of chromosome 19, or the centromeric region of chromosome 18. We speculate that a low copy number of sequences found in the peri-centromeric region of chromosome 19 and the centromeric region of chromosome 18 are present on chromosome 14 and generated a functional centromere through a complex rearrangement.

  18. Epigenetic engineering shows that a human centromere resists silencing mediated by H3K27me3/K9me3.

    Science.gov (United States)

    Martins, Nuno M C; Bergmann, Jan H; Shono, Nobuaki; Kimura, Hiroshi; Larionov, Vladimir; Masumoto, Hiroshi; Earnshaw, William C

    2016-01-01

    Centromeres are characterized by the centromere-specific H3 variant CENP-A, which is embedded in chromatin with a pattern characteristic of active transcription that is required for centromere identity. It is unclear how centromeres remain transcriptionally active despite being flanked by repressive pericentric heterochromatin. To further understand centrochromatin's response to repressive signals, we nucleated a Polycomb-like chromatin state within the centromere of a human artificial chromosome (HAC) by tethering the methyltransferase EZH2. This led to deposition of the H3K27me3 mark and PRC1 repressor binding. Surprisingly, this state did not abolish HAC centromere function or transcription, and this apparent resistance was not observed on a noncentromeric locus, where transcription was silenced. Directly tethering the reader/repressor PRC1 bypassed this resistance, inactivating the centromere. We observed analogous responses when tethering the heterochromatin Editor Suv39h1-methyltransferase domain (centromere resistance) or reader HP1α (centromere inactivation), respectively. Our results reveal that the HAC centromere can resist repressive pathways driven by H3K9me3/H3K27me3 and may help to explain how centromeres are able to resist inactivation by flanking heterochromatin. © 2016 Martins et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  19. The centromere: chromatin foundation for the kinetochore machinery

    National Research Council Canada - National Science Library

    Fukagawa, Tatsuo; Earnshaw, William C

    2014-01-01

    Since discovery of the centromere-specific histone H3 variant CENP-A, centromeres have come to be defined as chromatin structures that establish the assembly site for the complex kinetochore machinery...

  20. Characterization of centromeric histone H3 (CENH3 variants in cultivated and wild carrots (Daucus sp..

    Directory of Open Access Journals (Sweden)

    Frank Dunemann

    Full Text Available In eukaryotes, centromeres are the assembly sites for the kinetochore, a multi-protein complex to which spindle microtubules are attached at mitosis and meiosis, thereby ensuring segregation of chromosomes during cell division. They are specified by incorporation of CENH3, a centromere specific histone H3 variant which replaces canonical histone H3 in the nucleosomes of functional centromeres. To lay a first foundation of a putative alternative haploidization strategy based on centromere-mediated genome elimination in cultivated carrots, in the presented research we aimed at the identification and cloning of functional CENH3 genes in Daucus carota and three distantly related wild species of genus Daucus varying in basic chromosome numbers. Based on mining the carrot transcriptome followed by a subsequent PCR-based cloning, homologous coding sequences for CENH3s of the four Daucus species were identified. The ORFs of the CENH3 variants were very similar, and an amino acid sequence length of 146 aa was found in three out of the four species. Comparison of Daucus CENH3 amino acid sequences with those of other plant CENH3s as well as their phylogenetic arrangement among other dicot CENH3s suggest that the identified genes are authentic CENH3 homologs. To verify the location of the CENH3 protein in the kinetochore regions of the Daucus chromosomes, a polyclonal antibody based on a peptide corresponding to the N-terminus of DcCENH3 was developed and used for anti-CENH3 immunostaining of mitotic root cells. The chromosomal location of CENH3 proteins in the centromere regions of the chromosomes could be confirmed. For genetic localization of the CENH3 gene in the carrot genome, a previously constructed linkage map for carrot was used for mapping a CENH3-specific simple sequence repeat (SSR marker, and the CENH3 locus was mapped on the carrot chromosome 9.

  1. Using human artificial chromosomes to study centromere assembly and function.

    Science.gov (United States)

    Molina, Oscar; Kouprina, Natalay; Masumoto, Hiroshi; Larionov, Vladimir; Earnshaw, William C

    2017-10-01

    Centromeres are the site of assembly of the kinetochore, which directs chromosome segregation during cell division. Active centromeres are characterized by the presence of nucleosomes containing CENP-A and a specific chromatin environment that resembles that of active genes. Recent work using human artificial chromosomes (HAC) sheds light on the fine balance of different histone post-translational modifications and transcription that exists at centromeres for kinetochore assembly and maintenance. Here, we review the use of HAC technology to understand centromere assembly and function. We put particular emphasis on studies using the alphoidtetO HAC, whose centromere can be specifically modified for epigenetic engineering studies.

  2. Centromeric Transcription Regulates Aurora-B Localization and Activation

    Directory of Open Access Journals (Sweden)

    Michael D. Blower

    2016-05-01

    Full Text Available Centromeric transcription is widely conserved; however, it is not clear what role centromere transcription plays during mitosis. Here, I find that centromeres are transcribed in Xenopus egg extracts into a long noncoding RNA (lncRNA; cen-RNA that localizes to mitotic centromeres, chromatin, and spindles. cen-RNAs bind to the chromosomal passenger complex (CPC in vitro and in vivo. Blocking transcription or antisense inhibition of cen-RNA leads to a reduction of CPC localization to the inner centromere and misregulation of CPC component Aurora-B activation independently of known centromere recruitment pathways. Additionally, transcription is required for normal bipolar attachment of kinetochores to the mitotic spindle, consistent with a role for cen-RNA in CPC regulation. This work demonstrates that cen-RNAs promote normal kinetochore function through regulation of the localization and activation of the CPC and confirm that lncRNAs are components of the centromere.

  3. Diatom centromeres suggest a mechanism for nuclear DNA acquisition.

    Science.gov (United States)

    Diner, Rachel E; Noddings, Chari M; Lian, Nathan C; Kang, Anthony K; McQuaid, Jeffrey B; Jablanovic, Jelena; Espinoza, Josh L; Nguyen, Ngocquynh A; Anzelmatti, Miguel A; Jansson, Jakob; Bielinski, Vincent A; Karas, Bogumil J; Dupont, Christopher L; Allen, Andrew E; Weyman, Philip D

    2017-07-18

    Centromeres are essential for cell division and growth in all eukaryotes, and knowledge of their sequence and structure guides the development of artificial chromosomes for functional cellular biology studies. Centromeric proteins are conserved among eukaryotes; however, centromeric DNA sequences are highly variable. We combined forward and reverse genetic approaches with chromatin immunoprecipitation to identify centromeres of the model diatom Phaeodactylum tricornutum We observed 25 unique centromere sequences typically occurring once per chromosome, a finding that helps to resolve nuclear genome organization and indicates monocentric regional centromeres. Diatom centromere sequences contain low-GC content regions but lack repeats or other conserved sequence features. Native and foreign sequences with similar GC content to P. tricornutum centromeres can maintain episomes and recruit the diatom centromeric histone protein CENH3, suggesting nonnative sequences can also function as diatom centromeres. Thus, simple sequence requirements may enable DNA from foreign sources to persist in the nucleus as extrachromosomal episomes, revealing a potential mechanism for organellar and foreign DNA acquisition.

  4. Neocentrics and holokinetics (holocentrics): chromosomes out of the centromeric rules.

    Science.gov (United States)

    Guerra, M; Cabral, G; Cuacos, M; González-García, M; González-Sánchez, M; Vega, J; Puertas, M J

    2010-07-01

    The centromere appears as a single constriction at mitotic metaphase in most eukaryotic chromosomes. Holokinetic chromosomes are the exception to this rule because they do not show any centromeric constrictions. Holokinetic chromosomes are usually forgotten in most reviews about centromeres, despite their presence in a number of animal and plant species. They are generally linked to very intriguing and unusual mechanisms of mitosis and meiosis. Holokinetic chromosomes differ from monocentric chromosomes not only in the extension of the kinetochore plate, but also in many other peculiar karyological features, which could be understood as the 'holokinetic syndrome' that is reviewed in detail. Together with holokinetic chromosomes we review neocentromeric activity, a similarly intriguing case of regions able to pull chromosomes towards the poles without showing the main components reported to be essential to centromeric function. A neocentromere is a chromosomal region different from the true centromere in structure, DNA sequence and location, but is able to lead chromosomes to the cell poles in special circumstances. Neocentromeres have been reported in plants and animals showing different features. Both in humans and Drosophila, neocentric activity appears in somatic cells with defective chromosomes lacking a functional centromere. In most cases in plants, neocentromeres appear in chromosomes which have normal centromeres, but are active only during meiosis. Because of examples such as spontaneous or induced neocentromeres and holokinetic chromosomes, it is becoming less surprising that different structures and DNA sequences of centromeres appear in evolution. Copyright 2010 S. Karger AG, Basel.

  5. Structure of centromere chromatin: from nucleosome to chromosomal architecture.

    Science.gov (United States)

    Schalch, Thomas; Steiner, Florian A

    2017-08-01

    The centromere is essential for the segregation of chromosomes, as it serves as attachment site for microtubules to mediate chromosome segregation during mitosis and meiosis. In most organisms, the centromere is restricted to one chromosomal region that appears as primary constriction on the condensed chromosome and is partitioned into two chromatin domains: The centromere core is characterized by the centromere-specific histone H3 variant CENP-A (also called cenH3) and is required for specifying the centromere and for building the kinetochore complex during mitosis. This core region is generally flanked by pericentric heterochromatin, characterized by nucleosomes containing H3 methylated on lysine 9 (H3K9me) that are bound by heterochromatin proteins. During mitosis, these two domains together form a three-dimensional structure that exposes CENP-A-containing chromatin to the surface for interaction with the kinetochore and microtubules. At the same time, this structure supports the tension generated during the segregation of sister chromatids to opposite poles. In this review, we discuss recent insight into the characteristics of the centromere, from the specialized chromatin structures at the centromere core and the pericentromere to the three-dimensional organization of these regions that make up the functional centromere.

  6. Premature centromere division (PCD): a dominantly inherited cytogenetic anomaly.

    Science.gov (United States)

    Madan, K; Lindhout, D; Palan, A

    1987-10-01

    We describe a family with an increased frequency of cells with premature centromere division (PCD) of all chromosomes in four phenotypically normal individuals. This familial PCD phenomenon is apparently different from the well-described PCD of the X chromosome and from the centromere splitting in cells of patients with Roberts syndrome. Implications for genetic counseling are discussed.

  7. Replication, checkpoint suppression and structure of centromeric DNA.

    Science.gov (United States)

    Romeo, Francesco; Falbo, Lucia; Costanzo, Vincenzo

    2016-11-01

    Human centromeres contain large amounts of repetitive DNA sequences known as α satellite DNA, which can be difficult to replicate and whose functional role is unclear. Recently, we have characterized protein composition, structural organization and checkpoint response to stalled replication forks of centromeric chromatin reconstituted in Xenopus laevis egg extract. We showed that centromeric DNA has high affinity for SMC2-4 subunits of condensins and for CENP-A, it is enriched for DNA repair factors and suppresses the ATR checkpoint to ensure its efficient replication. We also showed that centromeric chromatin forms condensins enriched and topologically constrained DNA loops, which likely contribute to the overall structure of the centromere. These findings have important implications on how chromosomes are organized and genome stability is maintained in mammalian cells.

  8. HACking the centromere chromatin code: insights from human artificial chromosomes.

    Science.gov (United States)

    Bergmann, Jan H; Martins, Nuno M C; Larionov, Vladimir; Masumoto, Hiroshi; Earnshaw, William C

    2012-07-01

    The centromere is a specialized chromosomal region that serves as the assembly site of the kinetochore. At the centromere, CENP-A nucleosomes form part of a chromatin landscape termed centrochromatin. This chromatin environment conveys epigenetic marks regulating kinetochore formation. Recent work sheds light on the intricate relationship between centrochromatin state, the CENP-A assembly pathway and the maintenance of centromere function. Here, we review the emerging picture of how chromatin affects mammalian kinetochore formation. We place particular emphasis on data obtained from Human Artificial Chromosome (HAC) biology and the targeted engineering of centrochromatin using synthetic HACs. We discuss implications of these findings, which indicate that a delicate balance of histone modifications and chromatin state dictates both de novo centromere formation and the maintenance of centromere identity in dividing cell populations.

  9. Validation of the micronucleus-centromere assay for biological dosimetry

    Directory of Open Access Journals (Sweden)

    Wojcik A.

    2000-01-01

    Full Text Available The micronucleus assay is frequently used for purposes of biological dosimetry. Due to high interindividual variability in the spontaneous frequency of micronuclei, its sensitivity in the low dose region is poor. It has been suggested that this problem can be mitigated by selectively analyzing the frequency of those micronuclei which contain only acentric fragments. Using a pan-centromeric FISH probe we have studied the dose dependence of micronuclei with centromeres in peripheral lymphocytes of human donors. In contrast to previous publications, our approach is based on determining the relative frequency of micronuclei with and without centromeric signals. Our results confirm previous observations that in the low dose range of ionizing radiation, the micronucleus-centromere assay is more sensitive than the conventional micronucleus test.

  10. Cell cycle regulation of centromere function in Saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Brock, J.A.; Bloom, K. [Univ. of North Carolina, Chapel Hill, NC (United States)

    1993-12-31

    Accurate transmission of eukaryotic chromosomes is dependent on a specialized region of the chromosome, the centromere. The centromere is the site of assembly of the kinetochore, an integrated protein/DNA complex which acts as the point of attachment between individual chromosomes and the mitotic spindle. The presence of more than one centromere on a single chromosome (dicentric chromosome) is deleterious, resulting in broken chromosome derivatives and unstable chromosome inheritance. Dicentric chromosomes were first studied extensively in Zea mays. Cytogenetic observations of the mitotic behavior of these chromosomes illustrates a sequence of events termed a breakage-fusion-bridge cycle. When the two centromeres of a single chromosome are pulled to opposite poles during mitosis, the resulting anaphase bridge which forms between them is often broken. The broken ends are highly reactive, and by fusing with other chromsomes produce a number of chromosomal anomalies, including deletions, translocations, and the regeneration of dicentric chromosomes. This cycle persists until stable rearrangements are formed.

  11. Evidence for centromere drive in the holocentric chromosomes of Caenorhabditis.

    Directory of Open Access Journals (Sweden)

    František Zedek

    Full Text Available In monocentric organisms with asymmetric meiosis, the kinetochore proteins, such as CENH3 and CENP-C, evolve adaptively to counterbalance the deleterious effects of centromere drive, which is caused by the expansion of centromeric satellite repeats. The selection regimes that act on CENH3 and CENP-C genes have not been analyzed in organisms with holocentric chromosomes, although holocentrism is speculated to have evolved to suppress centromere drive. We tested both CENH3 and CENP-C for positive selection in several species of the holocentric genus Caenorhabditis using the maximum likelihood approach and sliding-window analysis. Although CENP-C did not show any signs of positive selection, positive selection has been detected in the case of CENH3. These results support the hypothesis that centromere drive occurs in Nematoda, at least in the telokinetic meiosis of Caenorhabditis.

  12. Sequential assembly of centromeric proteins in male mouse meiosis.

    Directory of Open Access Journals (Sweden)

    María Teresa Parra

    2009-03-01

    Full Text Available The assembly of the mitotic centromere has been extensively studied in recent years, revealing the sequence and regulation of protein loading to this chromosome domain. However, few studies have analyzed centromere assembly during mammalian meiosis. This study specifically targets this approach on mouse spermatocytes. We have found that during prophase I, the proteins of the chromosomal passenger complex Borealin, INCENP, and Aurora-B load sequentially to the inner centromere before Shugoshin 2 and MCAK. The last proteins to be assembled are the outer kinetochore proteins BubR1 and CENP-E. All these proteins are not detected at the centromere during anaphase/telophase I and are then reloaded during interkinesis. The loading sequence of the analyzed proteins is similar during prophase I and interkinesis. These findings demonstrate that the interkinesis stage, regularly overlooked, is essential for centromere and kinetochore maturation and reorganization previous to the second meiotic division. We also demonstrate that Shugoshin 2 is necessary for the loading of MCAK at the inner centromere, but is dispensable for the loading of the outer kinetochore proteins BubR1 and CENP-E.

  13. Dynamics of a novel centromeric histone variant CenH3 reveals the evolutionary ancestral timing of centromere biogenesis.

    Science.gov (United States)

    Dubin, Manu; Fuchs, Jörg; Gräf, Ralph; Schubert, Ingo; Nellen, Wolfgang

    2010-11-01

    The centromeric histone H3 variant (CenH3) serves to target the kinetochore to the centromeres and thus ensures correct chromosome segregation during mitosis and meiosis. The Dictyostelium H3-like variant H3v1 was identified as the CenH3 ortholog. Dictyostelium CenH3 has an extended N-terminal domain with no similarity to any other known proteins and a histone fold domain at its C-terminus. Within the histone fold, α-helix 2 (α2) and an extended loop 1 (L1) have been shown to be required for targeting CenH3 to centromeres. Compared to other known and putative CenH3 histones, Dictyostelium CenH3 has a shorter L1, suggesting that the extension is not an obligatory feature. Through ChIP analysis and fluorescence microscopy of live and fixed cells, we provide here the first survey of centromere structure in amoebozoa. The six telocentric centromeres were found to mostly consist of all the DIRS-1 elements and to associate with H3K9me3. During interphase, the centromeres remain attached to the centrosome forming a single CenH3-containing cluster. Loading of Dictyostelium CenH3 onto centromeres occurs at the G2/prophase transition, in contrast to the anaphase/telophase loading of CenH3 observed in metazoans. This suggests that loading during G2/prophase is the ancestral eukaryotic mechanism and that anaphase/telophase loading of CenH3 has evolved more recently after the amoebozoa diverged from the animal linage.

  14. DNA Topology and Global Architecture of Point Centromeres

    Directory of Open Access Journals (Sweden)

    Ofelia Díaz-Ingelmo

    2015-10-01

    Full Text Available DNA is wrapped in a left-handed fashion around histone octasomes containing the centromeric histone H3 variant CENP-A. However, DNA topology studies have suggested that DNA is wrapped in a right-handed manner around the CENP-A nucleosome that occupies the yeast point centromere. Here, we determine the DNA linking number difference (ΔLk stabilized by the yeast centromere and the contribution of the centromere determining elements (CDEI, CDEII, and CDEIII. We show that the intrinsic architecture of the yeast centromere stabilizes +0.6 units of ΔLk. This topology depends on the integrity of CDEII and CDEIII, but it is independent of cbf1 binding to CDEI and of the variable length of CDEII. These findings suggest that the interaction of the CBF3 complex with CDEIII and a distal CDEII segment configures a right-handed DNA loop that excludes CDEI. This loop is then occupied by a CENP-A histone complex, which does not have to be inherently right-handed.

  15. Transposable elements: genome innovation, chromosome diversity, and centromere conflict.

    Science.gov (United States)

    Klein, Savannah J; O'Neill, Rachel J

    2018-01-13

    Although it was nearly 70 years ago when transposable elements (TEs) were first discovered "jumping" from one genomic location to another, TEs are now recognized as contributors to genomic innovations as well as genome instability across a wide variety of species. In this review, we illustrate the ways in which active TEs, specifically retroelements, can create novel chromosome rearrangements and impact gene expression, leading to disease in some cases and species-specific diversity in others. We explore the ways in which eukaryotic genomes have evolved defense mechanisms to temper TE activity and the ways in which TEs continue to influence genome structure despite being rendered transpositionally inactive. Finally, we focus on the role of TEs in the establishment, maintenance, and stabilization of critical, yet rapidly evolving, chromosome features: eukaryotic centromeres. Across centromeres, specific types of TEs participate in genomic conflict, a balancing act wherein they are actively inserting into centromeric domains yet are harnessed for the recruitment of centromeric histones and potentially new centromere formation.

  16. No longer a nuisance: long non-coding RNAs join CENP-A in epigenetic centromere regulation.

    Science.gov (United States)

    Rošić, Silvana; Erhardt, Sylvia

    2016-04-01

    Centromeres represent the basis for kinetochore formation, and are essential for proper chromosome segregation during mitosis. Despite these essential roles, centromeres are not defined by specific DNA sequences, but by epigenetic means. The histone variant CENP-A controls centromere identity epigenetically and is essential for recruiting kinetochore components that attach the chromosomes to the mitotic spindle during mitosis. Recently, a new player in centromere regulation has emerged: long non-coding RNAs transcribed from repetitive regions of centromeric DNA function in regulating centromeres epigenetically. This review summarizes recent findings on the essential roles that transcription, pericentromeric transcripts, and centromere-derived RNAs play in centromere biology.

  17. Sequence conservation of an avian centromeric repeated DNA component.

    Science.gov (United States)

    Madsen, C S; Brooks, J E; de Kloet, E; de Kloet, S R

    1994-06-01

    The approximately 190-bp centromeric repeat monomers of the spur-winged lapwing (Vanellus spinosus, Charadriidae), the Chilean flamingo (Phoenicopterus chilensis, Phoenicopteridae), the sarus crane (Grus antigone, Gruidae), parrots (Psittacidae), waterfowl (Anatidae), and the merlin (Falco columbarius, Falconidae) contain elements that are interspecifically highly variable, as well as elements (trinucleotides and higher order oligonucleotides) that are highly conserved in sequence and relative location within the repeat. Such conservation suggests that the centromeric repeats of these avian species have evolved from a common ancestral sequence that may date from very early stages of avian radiation.

  18. Centromeric banding pattern of mitotic chromosomes in Vigna vexillata

    African Journals Online (AJOL)

    Administrator

    Horticultural Research Institute for giving me the opportunity for the research. REFERENCES. Adetula, O.A., 1999: Karyotype and Centromeric banding pattern of chromosomes in Vigna species Ph.D Thesis p.127. *Busch W, Herrman, R.G., Houben, A. and Martin, R., 1996. Efficient preparation of plant metaphase spreads.

  19. Centromeric banding pattern of mitotic chromosomes in Vigna vexillata

    African Journals Online (AJOL)

    Vigna vexillata chromosome characterization was carried out using the Leishman C- banding technique. The results showed that the chromosomes mostly exhibited bands at both the centromeric and telomeric regions. These bands will serve, as a valuable marker for the identification of the chromosomes. Chromosomes 2 ...

  20. Recombination patterns reveal information about centromere location on linkage maps

    DEFF Research Database (Denmark)

    Limborg, Morten T.; McKinney, Garrett J.; Seeb, Lisa W.

    2016-01-01

    . mykiss) characterized by low and unevenly distributed recombination – a general feature of male meiosis in many species. Further, a high frequency of double crossovers along chromosome arms in barley reduced resolution for locating centromeric regions on most linkage groups. Despite these limitations...

  1. Hypomethylation of LINE-1, and not centromeric SAT-α, is associated with centromeric instability in head and neck squamous cell carcinoma.

    Science.gov (United States)

    Martínez, Jorge García; Pérez-Escuredo, Jhudit; Castro-Santos, Patricia; Marcos, César Alvarez; Pendás, José Luis Llorente; Fraga, Mario F; Hermsen, Mario A

    2012-08-01

    Head and neck squamous cell carcinoma (HNSCC) is a tumour type that generally carries very complex chromosomal aberrations. An interesting feature is the elevated occurrence (58 %) of whole arm translocations and isochromosomes, resulting from breakage and illegitimate recombination in centromeric or pericentromeric regions. We hypothesized that alterations in DNA methylation may play a role in the breakage of centromeric repeat sequences in these tumours. We studied the DNA methylation status of global repeats (LINE-1), subtelomeric repeats (D4Z4) and centromeric repeats (SAT-α) in relation to centromeric instability in a series of HNSCC cancer cell lines and primary tumours. We analysed the methylation status by pyrosequencing and the chromosomal aberrations by microarray CGH. We found a significant association between centromeric instability and hypomethylation of LINE-1, but not D4Z4 and SAT-α. These data suggest that centromeric instability is associated with genomic DNA hypomethylation only when occurring at specific DNA repeat sequences.

  2. High-resolution mapping and transcriptional activity analysis of chicken centromere sequences on giant lampbrush chromosomes.

    Science.gov (United States)

    Krasikova, Alla; Fukagawa, Tatsuo; Zlotina, Anna

    2012-12-01

    Exploration into morphofunctional organisation of centromere DNA sequences is important for understanding the mechanisms of kinetochore specification and assembly. In-depth epigenetic analysis of DNA fragments associated with centromeric nucleosome proteins has demonstrated unique features of centromere organisation in chicken karyotype: there are both mature centromeres, which comprise chromosome-specific homogeneous arrays of tandem repeats, and recently evolved primitive centromeres, which consist of non-tandemly organised DNA sequences. In this work, we describe the arrangement and transcriptional activity of chicken centromere repeats for Cen1, Cen2, Cen3, Cen4, Cen7, Cen8, and Cen11 and non-repetitive centromere sequences of chromosomes 5, 27, and Z using highly elongated lampbrush chromosomes, which are characteristic of the diplotene stage of oogenesis. The degree of chromatin packaging and fine spatial organisations of tandemly repetitive and non-tandemly repetitive centromeric sequences significantly differ at the lampbrush stage. Using DNA/RNA FISH, we have demonstrated that during the lampbrush stage, DNA sequences are transcribed within the centromere regions of chromosomes that lack centromere-specific tandem repeats. In contrast, chromosome-specific centromeric repeats Cen1, Cen2, Cen3, Cen4, Cen7, Cen8, and Cen11 do not demonstrate any transcriptional activity during the lampbrush stage. In addition, we found that CNM repeat cluster localises adjacent to non-repetitive centromeric sequences in chicken microchromosome 27 indicating that centromere region in this chromosome is repeat-rich. Cross-species FISH allowed localisation of the sequences homologous to centromeric DNA of chicken chromosomes 5 and 27 in centromere regions of quail orthologous chromosomes.

  3. Divergence in centromere structure distinguishes related genomes in Coix lacryma-jobi and its wild relative.

    Science.gov (United States)

    Han, Yonghua; Wang, Guixiang; Liu, Zhao; Liu, Jinhua; Yue, Wei; Song, Rentao; Zhang, Xueyong; Jin, Weiwei

    2010-02-01

    Knowledge about the composition and structure of centromeres is critical for understanding how centromeres perform their functional roles. Here, we report the sequences of one centromere-associated bacterial artificial chromosome clone from a Coix lacryma-jobi library. Two Ty3/gypsy-class retrotransposons, centromeric retrotransposon of C. lacryma-jobi (CRC) and peri-centromeric retrotransposon of C. lacryma-jobi, and a (peri)centromere-specific tandem repeat with a unit length of 153 bp were identified. The CRC is highly homologous to centromere-specific retrotransposons reported in grass species. An 80-bp DNA region in the 153-bp satellite repeat was found to be conserved to centromeric satellite repeats from maize, rice, and pearl millet. Fluorescence in situ hybridization showed that the three repetitive sequences were located in (peri-)centromeric regions of both C. lacryma-jobi and Coix aquatica. However, the 153-bp satellite repeat was only detected on 20 out of the 30 chromosomes in C. aquatica. Immunostaining with an antibody against rice CENH3 indicates that the 153-bp satellite repeat and CRC might be both the major components for functional centromeres, but not all the 153-bp satellite repeats or CRC sequences are associated with CENH3. The evolution of centromeric repeats of C. lacryma-jobi during the polyploidization was discussed.

  4. Transvection at the vestigial locus of Drosophila melanogaster.

    Science.gov (United States)

    Coulthard, Alistair B; Nolan, Nadia; Bell, John B; Hilliker, Arthur J

    2005-08-01

    Transvection is a phenomenon wherein gene expression is effected by the interaction of alleles in trans and often results in partial complementation between mutant alleles. Transvection is dependent upon somatic pairing between homologous chromosome regions and is a form of interallelic complementation that does not occur at the polypeptide level. In this study we demonstrated that transvection could occur at the vestigial (vg) locus by revealing that partial complementation between two vg mutant alleles could be disrupted by changing the genomic location of the alleles through chromosome rearrangement. If chromosome rearrangements affect transvection by disrupting somatic pairing, then combining chromosome rearrangements that restore somatic pairing should restore transvection. We were able to restore partial complementation in numerous rearrangement trans-heterozygotes, thus providing substantial evidence that the observed complementation at vg results from a transvection effect. Cytological analyses revealed this transvection effect to have a large proximal critical region, a feature common to other transvection effects. In the Drosophila interphase nucleus, paired chromosome arms are separated into distinct, nonoverlapping domains. We propose that if the relative position of each arm in the nucleus is determined by the centromere as a relic of chromosome positions after the last mitotic division, then a locus will be displaced to a different territory of the interphase nucleus relative to its nonrearranged homolog by any rearrangement that links that locus to a different centromere. This physical displacement in the nucleus hinders transvection by disrupting the somatic pairing of homologous chromosomes and gives rise to proximal critical regions.

  5. Uncoupling of satellite DNA and centromeric function in the genus Equus.

    Directory of Open Access Journals (Sweden)

    Francesca M Piras

    2010-02-01

    Full Text Available In a previous study, we showed that centromere repositioning, that is the shift along the chromosome of the centromeric function without DNA sequence rearrangement, has occurred frequently during the evolution of the genus Equus. In this work, the analysis of the chromosomal distribution of satellite tandem repeats in Equus caballus, E. asinus, E. grevyi, and E. burchelli highlighted two atypical features: 1 several centromeres, including the previously described evolutionary new centromeres (ENCs, seem to be devoid of satellite DNA, and 2 satellite repeats are often present at non-centromeric termini, probably corresponding to relics of ancestral now inactive centromeres. Immuno-FISH experiments using satellite DNA and antibodies against the kinetochore protein CENP-A demonstrated that satellite-less primary constrictions are actually endowed with centromeric function. The phylogenetic reconstruction of centromere repositioning events demonstrates that the acquisition of satellite DNA occurs after the formation of the centromere during evolution and that centromeres can function over millions of years and many generations without detectable satellite DNA. The rapidly evolving Equus species gave us the opportunity to identify different intermediate steps along the full maturation of ENCs.

  6. Uncoupling of Satellite DNA and Centromeric Function in the Genus Equus

    Science.gov (United States)

    Magnani, Elisa; Bertoni, Livia; Attolini, Carmen; Khoriauli, Lela; Raimondi, Elena; Giulotto, Elena

    2010-01-01

    In a previous study, we showed that centromere repositioning, that is the shift along the chromosome of the centromeric function without DNA sequence rearrangement, has occurred frequently during the evolution of the genus Equus. In this work, the analysis of the chromosomal distribution of satellite tandem repeats in Equus caballus, E. asinus, E. grevyi, and E. burchelli highlighted two atypical features: 1) several centromeres, including the previously described evolutionary new centromeres (ENCs), seem to be devoid of satellite DNA, and 2) satellite repeats are often present at non-centromeric termini, probably corresponding to relics of ancestral now inactive centromeres. Immuno-FISH experiments using satellite DNA and antibodies against the kinetochore protein CENP-A demonstrated that satellite-less primary constrictions are actually endowed with centromeric function. The phylogenetic reconstruction of centromere repositioning events demonstrates that the acquisition of satellite DNA occurs after the formation of the centromere during evolution and that centromeres can function over millions of years and many generations without detectable satellite DNA. The rapidly evolving Equus species gave us the opportunity to identify different intermediate steps along the full maturation of ENCs. PMID:20169180

  7. Epigenetically-inherited centromere and neocentromere DNA replicates earliest in S-phase.

    Directory of Open Access Journals (Sweden)

    Amnon Koren

    2010-08-01

    Full Text Available Eukaryotic centromeres are maintained at specific chromosomal sites over many generations. In the budding yeast Saccharomyces cerevisiae, centromeres are genetic elements defined by a DNA sequence that is both necessary and sufficient for function; whereas, in most other eukaryotes, centromeres are maintained by poorly characterized epigenetic mechanisms in which DNA has a less definitive role. Here we use the pathogenic yeast Candida albicans as a model organism to study the DNA replication properties of centromeric DNA. By determining the genome-wide replication timing program of the C. albicans genome, we discovered that each centromere is associated with a replication origin that is the first to fire on its respective chromosome. Importantly, epigenetic formation of new ectopic centromeres (neocentromeres was accompanied by shifts in replication timing, such that a neocentromere became the first to replicate and became associated with origin recognition complex (ORC components. Furthermore, changing the level of the centromere-specific histone H3 isoform led to a concomitant change in levels of ORC association with centromere regions, further supporting the idea that centromere proteins determine origin activity. Finally, analysis of centromere-associated DNA revealed a replication-dependent sequence pattern characteristic of constitutively active replication origins. This strand-biased pattern is conserved, together with centromere position, among related strains and species, in a manner independent of primary DNA sequence. Thus, inheritance of centromere position is correlated with a constitutively active origin of replication that fires at a distinct early time. We suggest a model in which the distinct timing of DNA replication serves as an epigenetic mechanism for the inheritance of centromere position.

  8. Comparative mapping of human alphoid centromeric sequences in great apes

    Energy Technology Data Exchange (ETDEWEB)

    Archidiacono, N.; Antonacci, R.; Marzella, R. [Instituto di Genetica, Bari (Italy)] [and others

    1994-09-01

    Metaphase spreads from chimpanzees (Pan troglodytes and Pan paniscus) and gorilla (Gorilla gorilla) have been hybridized in situ with 27 alphoid DNA probes specific for the centromere of human chromosomes, to investigate the evolutionary relationship between centromeric regions of human and great apes. The results showed that most human probes do not recognize their corresponding homologs in great apes. Chromosome X is the only chromosome showing localization consistency in all the four species. Each suprachromosomal family (SCF) exhibits a distinct and peculiar evolutionary history. SCF1 (chromosomes 1, 3, 6, 7, 19, 12, 16) is very heterogeneous: some probes gave intense signals, but always on non-homologous chromosomes; others did not produce any hybridization signal. All probes localized on SCF2 (chromosomes 2, 4, 8, 9, 13, 14, 15, 18, 20, 21, and 22) recognize a single chromosome: chromosome 11 (phylogenetic IX) in PTR and PPA; chromosome 4 (phylogenetic V) in GGO. SCF3 subsets (chromosomes 1, 11, 17, X) are substantially conserved in PTR and PPA, but not in GGO, with the exception restricted to chromosome X. No signals have been detected on PPA chromosomes I, III, IV, V, VI and in PTR chromosomes V, suggesting that the centromeric region of some chromsomes have probably lost homology with human alphoid sequences.

  9. Structure of the CENP-A nucleosome and its implications for centromeric chromatin architecture.

    Science.gov (United States)

    Tachiwana, Hiroaki; Kurumizaka, Hitoshi

    2011-01-01

    Centromeres are dictated by the epigenetic inheritance of the centromeric nucleosome containing the centromere-specific histone H3 variant, CENP-A. The structure of the CENP-A nucleosome has been considered to be the fundamental architecture of the centromeric chromatin. Controversy exists in the literature regarding the CENP-A nucleosome structures, with octasome, hemisome, compact octasome, hexasome, and tetrasome models being reported. Some of these CENP-A nucleosome models may correspond to transient intermediates for the assembly of the mature CENP-A nucleosome; however, their significances are still unclear. Therefore, the structure of the mature CENP-A nucleosome has been eagerly awaited. We reconstituted the human CENP-A nucleosome with its cognate centromeric DNA fragment, and determined its crystal structure. In this review, we describe the structure and the physical properties of the CENP-A nucleosome, and discuss their implications for centromeric chromatin architecture.

  10. Restructuring of Holocentric Centromeres During Meiosis in the Plant Rhynchospora pubera.

    Science.gov (United States)

    Marques, André; Schubert, Veit; Houben, Andreas; Pedrosa-Harand, Andrea

    2016-10-01

    Centromeres are responsible for the correct segregation of chromosomes during mitosis and meiosis. Holocentric chromosomes, characterized by multiple centromere units along each chromatid, have particular adaptations to ensure regular disjunction during meiosis. Here we show by detecting CENH3, CENP-C, tubulin, and centromeric repeats that holocentromeres may be organized differently in mitosis and meiosis of Rhynchospora pubera Contrasting to the mitotic linear holocentromere organization, meiotic centromeres show several clusters of centromere units (cluster-holocentromeres) during meiosis I. They accumulate along the poleward surface of bivalents where spindle fibers perpendicularly attach. During meiosis II, the cluster-holocentromeres are mostly present in the midregion of each chromatid. A linear holocentromere organization is restored after meiosis during pollen mitosis. Thus, a not yet described case of a cluster-holocentromere organization, showing a clear centromere restructuration between mitosis and meiosis, was identified in a holocentric organism. Copyright © 2016 by the Genetics Society of America.

  11. Centromere strength provides the cell biological basis for meiotic drive and karyotype evolution in mice

    OpenAIRE

    Chmátal, Lukáš; Gabriel, Sofia I.; Mitsainas, George P.; Martínez-Vargas, Jessica; Ventura, Jacint; Searle, Jeremy B.; Schultz, Richard M.; Lampson, Michael A.

    2014-01-01

    Mammalian karyotypes (number and structure of chromosomes) can vary dramatically over short evolutionary time frames [1–3]. There are examples of massive karyotype conversion, from mostly telocentric (centromere terminal) to mostly metacentric (centromere internal), in 102–105 years [4, 5]. These changes typically reflect rapid fixation of Robertsonian (Rb) fusions, a common chromosomal rearrangement that joins two telocentric chromosomes at their centromeres to create one metacentric [5]. Fi...

  12. Centromere Locations in Brassica A and C Genomes Revealed Through Half-Tetrad Analysis

    OpenAIRE

    Mason, Annaliese S; Rousseau-Gueutin, Mathieu; Morice, Jérôme; Bayer, Philipp E.; Besharat, Naghmeh; Cousin, Anouska; Pradhan, Aneeta; Parkin, Isobel A. P.; Chèvre, Anne-Marie; Batley, Jacqueline; Nelson, Matthew N.

    2015-01-01

    Locating centromeres on genome sequences can be challenging. The high density of repetitive elements in these regions makes sequence assembly problematic, especially when using short-read sequencing technologies. It can also be difficult to distinguish between active and recently extinct centromeres through sequence analysis. An effective solution is to identify genetically active centromeres (functional in meiosis) by half-tetrad analysis. This genetic approach involves detecting heterozygos...

  13. Centromere strength provides the cell biological basis for meiotic drive and karyotype evolution in mice.

    Science.gov (United States)

    Chmátal, Lukáš; Gabriel, Sofia I; Mitsainas, George P; Martínez-Vargas, Jessica; Ventura, Jacint; Searle, Jeremy B; Schultz, Richard M; Lampson, Michael A

    2014-10-06

    Mammalian karyotypes (number and structure of chromosomes) can vary dramatically over short evolutionary time frames. There are examples of massive karyotype conversion, from mostly telocentric (centromere terminal) to mostly metacentric (centromere internal), in 10(2)-10(5) years. These changes typically reflect rapid fixation of Robertsonian (Rb) fusions, a common chromosomal rearrangement that joins two telocentric chromosomes at their centromeres to create one metacentric. Fixation of Rb fusions can be explained by meiotic drive: biased chromosome segregation during female meiosis in violation of Mendel's first law. However, there is no mechanistic explanation of why fusions would preferentially segregate to the egg in some populations, leading to fixation and karyotype change, while other populations preferentially eliminate the fusions and maintain a telocentric karyotype. Here we show, using both laboratory models and wild mice, that differences in centromere strength predict the direction of drive. Stronger centromeres, manifested by increased kinetochore protein levels and altered interactions with spindle microtubules, are preferentially retained in the egg. We find that fusions preferentially segregate to the polar body in laboratory mouse strains when the fusion centromeres are weaker than those of telocentrics. Conversely, fusion centromeres are stronger relative to telocentrics in natural house mouse populations that have changed karyotype by accumulating metacentric fusions. Our findings suggest that natural variation in centromere strength explains how the direction of drive can switch between populations. They also provide a cell biological basis of centromere drive and karyotype evolution. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Functional centromeres determine the activation time of pericentric origins of DNA replication in Saccharomyces cerevisiae.

    Directory of Open Access Journals (Sweden)

    Thomas J Pohl

    Full Text Available The centromeric regions of all Saccharomyces cerevisiae chromosomes are found in early replicating domains, a property conserved among centromeres in fungi and some higher eukaryotes. Surprisingly, little is known about the biological significance or the mechanism of early centromere replication; however, the extensive conservation suggests that it is important for chromosome maintenance. Do centromeres ensure their early replication by promoting early activation of nearby origins, or have they migrated over evolutionary time to reside in early replicating regions? In Candida albicans, a neocentromere contains an early firing origin, supporting the first hypothesis but not addressing whether the new origin is intrinsically early firing or whether the centromere influences replication time. Because the activation time of individual origins is not an intrinsic property of S. cerevisiae origins, but is influenced by surrounding sequences, we sought to test the hypothesis that centromeres influence replication time by moving a centromere to a late replication domain. We used a modified Meselson-Stahl density transfer assay to measure the kinetics of replication for regions of chromosome XIV in which either the functional centromere or a point-mutated version had been moved near origins that reside in a late replication region. We show that a functional centromere acts in cis over a distance as great as 19 kb to advance the initiation time of origins. Our results constitute a direct link between establishment of the kinetochore and the replication initiation machinery, and suggest that the proposed higher-order structure of the pericentric chromatin influences replication initiation.

  15. New clues to understand how CENP-A maintains centromere identity

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    Losada Ana

    2011-05-01

    Full Text Available Abstract The centromere is a specialized chromosomal region that directs the formation of the kinetochore, a huge protein assembly that acts as the attachment site for spindle microtubules and carries out chromosome movement during cell division. Centromere loss or the presence of extra centromeres adversely affect chromosome segregation and may result in aneuploidy, a condition found in many human tumors and a major cause of miscarriages and birth defects. Consequently, understanding the basis of centromere determination and propagation is of great relevance to both fundamental and clinical research. In recent years, it has become clear that centromeres are defined by the presence of a histone H3 variant known as Centromere Protein A, CENP-A, or CenH3. Much effort has been devoted to understanding the mechanisms that drive the assembly of CENP-A containing nucleosomes exclusively onto centromeric DNA, as well as the peculiar structure of these nucleosomes. We have recently developed an immunofluorescence-based assay that measures CENP-A incorporation in the centromeres of chromosomes assembled in Xenopus egg extracts. The spatial and temporal specificity of CENP-A deposition observed in human cells can be recapitulated in this in vitro system, making it suitable to dissect the precise role of the different factors that contribute to this pathway. Here, we discuss our results together with other recent advances in our understanding of the mechanisms that mediate centromere inheritance.

  16. Hairpin structures formed by alpha satellite DNA of human centromeres are cleaved by human topoisomerase IIα

    Science.gov (United States)

    Jonstrup, Anette Thyssen; Thomsen, Tina; Wang, Yong; Knudsen, Birgitta R.; Koch, Jørn; Andersen, Anni H.

    2008-01-01

    Although centromere function has been conserved through evolution, apparently no interspecies consensus DNA sequence exists. Instead, centromere DNA may be interconnected through the formation of certain DNA structures creating topological binding sites for centromeric proteins. DNA topoisomerase II is a protein, which is located at centromeres, and enzymatic topoisomerase II activity correlates with centromere activity in human cells. It is therefore possible that topoisomerase II recognizes and interacts with the alpha satellite DNA of human centromeres through an interaction with potential DNA structures formed solely at active centromeres. In the present study, human topoisomerase IIα-mediated cleavage at centromeric DNA sequences was examined in vitro. The investigation has revealed that the enzyme recognizes and cleaves a specific hairpin structure formed by alpha satellite DNA. The topoisomerase introduces a single-stranded break at the hairpin loop in a reaction, where DNA ligation is partly uncoupled from the cleavage reaction. A mutational analysis has revealed, which features of the hairpin are required for topoisomerease IIα-mediated cleavage. Based on this a model is discussed, where topoisomerase II interacts with two hairpins as a mediator of centromere cohesion. PMID:18824478

  17. Replication Fork Stability Is Essential for the Maintenance of Centromere Integrity in the Absence of Heterochromatin

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    Pao-Chen Li

    2013-03-01

    Full Text Available The centromere of many eukaryotes contains highly repetitive sequences marked by methylation of histone H3K9 by Clr4KMT1. This recruits multiple heterochromatin proteins, including Swi6 and Chp1, to form a rigid centromere and ensure accurate chromosome segregation. In the absence of heterochromatin, cells show an increased rate of recombination in the centromere, as well as chromosome loss. These defects are severely aggravated by loss of replication fork stability. Thus, heterochromatin proteins and replication fork protection mechanisms work in concert to prevent abnormal recombination, preserve centromere integrity, and ensure faithful chromosome segregation.

  18. Neocentromeres Provide Chromosome Segregation Accuracy and Centromere Clustering to Multiple Loci along a Candida albicans Chromosome.

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    Laura S Burrack

    2016-09-01

    Full Text Available Assembly of kinetochore complexes, involving greater than one hundred proteins, is essential for chromosome segregation and genome stability. Neocentromeres, or new centromeres, occur when kinetochores assemble de novo, at DNA loci not previously associated with kinetochore proteins, and they restore chromosome segregation to chromosomes lacking a functional centromere. Neocentromeres have been observed in a number of diseases and may play an evolutionary role in adaptation or speciation. However, the consequences of neocentromere formation on chromosome missegregation rates, gene expression, and three-dimensional (3D nuclear structure are not well understood. Here, we used Candida albicans, an organism with small, epigenetically-inherited centromeres, as a model system to study the functions of twenty different neocentromere loci along a single chromosome, chromosome 5. Comparison of neocentromere properties relative to native centromere functions revealed that all twenty neocentromeres mediated chromosome segregation, albeit to different degrees. Some neocentromeres also caused reduced levels of transcription from genes found within the neocentromere region. Furthermore, like native centromeres, neocentromeres clustered in 3D with active/functional centromeres, indicating that formation of a new centromere mediates the reorganization of 3D nuclear architecture. This demonstrates that centromere clustering depends on epigenetically defined function and not on the primary DNA sequence, and that neocentromere function is independent of its distance from the native centromere position. Together, the results show that a neocentromere can form at many loci along a chromosome and can support the assembly of a functional kinetochore that exhibits native centromere functions including chromosome segregation accuracy and centromere clustering within the nucleus.

  19. Plasmodium falciparum centromeres display a unique epigenetic makeup and cluster prior to and during schizogony.

    Science.gov (United States)

    Hoeijmakers, Wieteke A M; Flueck, Christian; Françoijs, Kees-Jan; Smits, Arne H; Wetzel, Johanna; Volz, Jennifer C; Cowman, Alan F; Voss, Till; Stunnenberg, Hendrik G; Bártfai, Richárd

    2012-09-01

    Centromeres are essential for the faithful transmission of chromosomes to the next generation, therefore being essential in all eukaryotic organisms. The centromeres of Plasmodium falciparum, the causative agent of the most severe form of malaria, have been broadly mapped on most chromosomes, but their epigenetic composition remained undefined. Here, we reveal that the centromeric histone variant PfCENH3 occupies a 4-4.5 kb region on each P. falciparum chromosome, which is devoid of pericentric heterochromatin but harbours another histone variant, PfH2A.Z. These CENH3 covered regions pinpoint the exact position of the centromere on all chromosomes and revealed that all centromeric regions have similar size and sequence composition. Immunofluorescence assay of PfCENH3 strongly suggests that P. falciparum centromeres cluster to a single nuclear location prior to and during mitosis and cytokinesis but dissociate soon after invasion. In summary, we reveal a dynamic association of Plasmodium centromeres, which bear a unique epigenetic signature and conform to a strict structure. These findings suggest that DNA-associated and epigenetic elements play an important role in centromere establishment in this important human pathogen. © 2012 Blackwell Publishing Ltd.

  20. Organization and evolution of Gorilla centromeric DNA from old strategies to new approaches.

    Science.gov (United States)

    Catacchio, C R; Ragone, R; Chiatante, G; Ventura, M

    2015-09-21

    The centromere/kinetochore interaction is responsible for the pairing and segregation of replicated chromosomes in eukaryotes. Centromere DNA is portrayed as scarcely conserved, repetitive in nature, quickly evolving and protein-binding competent. Among primates, the major class of centromeric DNA is the pancentromeric α-satellite, made of arrays of 171 bp monomers, repeated in a head-to-tail pattern. α-satellite sequences can either form tandem heterogeneous monomeric arrays or assemble in higher-order repeats (HORs). Gorilla centromere DNA has barely been characterized, and data are mainly based on hybridizations of human alphoid sequences. We isolated and finely characterized gorilla α-satellite sequences and revealed relevant structure and chromosomal distribution similarities with other great apes as well as gorilla-specific features, such as the uniquely octameric structure of the suprachromosomal family-2 (SF2). We demonstrated for the first time the orthologous localization of alphoid suprachromosomal families-1 and -2 (SF1 and SF2) between human and gorilla in contrast to chimpanzee centromeres. Finally, the discovery of a new 189 bp monomer type in gorilla centromeres unravels clues to the role of the centromere protein B, paving the way to solve the significance of the centromere DNA's essential repetitive nature in association with its function and the peculiar evolution of the α-satellite sequence.

  1. Holokinetic centromeres and efficient telomere healing enable rapid karyotype evolution.

    Science.gov (United States)

    Jankowska, Maja; Fuchs, Jörg; Klocke, Evelyn; Fojtová, Miloslava; Polanská, Pavla; Fajkus, Jiří; Schubert, Veit; Houben, Andreas

    2015-12-01

    Species with holocentric chromosomes are often characterized by a rapid karyotype evolution. In contrast to species with monocentric chromosomes where acentric fragments are lost during cell division, breakage of holocentric chromosomes creates fragments with normal centromere activity. To decipher the mechanism that allows holocentric species an accelerated karyotype evolution via chromosome breakage, we analyzed the chromosome complements of irradiated Luzula elegans plants. The resulting chromosomal fragments and rearranged chromosomes revealed holocentromere-typical CENH3 and histone H2AThr120ph signals as well as the same mitotic mobility like unfragmented chromosomes. Newly synthesized telomeres at break points become detectable 3 weeks after irradiation. The presence of active telomerase suggests a telomerase-based mechanism of chromosome healing. A successful transmission of holocentric chromosome fragments across different generations was found for most offspring of irradiated plants. Hence, a combination of holokinetic centromere activity and the fast formation of new telomeres at break points enables holocentric species a rapid karyotype evolution involving chromosome fissions and rearrangements.

  2. Centromere inactivation on a neo-Y fusion chromosome in threespine stickleback fish.

    Science.gov (United States)

    Cech, Jennifer N; Peichel, Catherine L

    2016-12-01

    Having one and only one centromere per chromosome is essential for proper chromosome segregation during both mitosis and meiosis. Chromosomes containing two centromeres are known as dicentric and often mis-segregate during cell division, resulting in aneuploidy or chromosome breakage. Dicentric chromosome can be stabilized by centromere inactivation, a process which reestablishes monocentric chromosomes. However, little is known about this process in naturally occurring dicentric chromosomes. Using a combination of fluorescence in situ hybridization (FISH) and immunofluorescence combined with FISH (IF-FISH) on metaphase chromosome spreads, we demonstrate that centromere inactivation has evolved on a neo-Y chromosome fusion in the Japan Sea threespine stickleback fish (Gasterosteus nipponicus). We found that the centromere derived from the ancestral Y chromosome has been inactivated. Our data further suggest that there have been genetic changes to this centromere in the two million years since the formation of the neo-Y chromosome, but it remains unclear whether these genetic changes are a cause or consequence of centromere inactivation.

  3. [Detection of maize centromeric repeats in the relatives of maize using fluorescence in situ hybridization].

    Science.gov (United States)

    She, Chao-Wen; Jiang, Xiang-Hui; Song, Yun-Chun; Liu, Wei

    2010-03-01

    In order to analyze the conservation of maize centromeric satellite DNA (CentC) and centromeric retrotransposon (CRM) in the subspecies and relatives of Zea mays, dual fluorescence in situ hybridization (FISH) was used to detect the existence and distribution of the above two repetitive sequences in Zea mays ssp. mexicana, Z. diploperennis, Z. perennis, Tripsacum dactyloides, Coix lacryma-jobi, and Sorghum bicolor. In Z. mays ssp. mexicana, Z. diploperennis, and Z. perennis, both CentC and CRM probes produced strong or relatively strong signals in the centromeric regions of all chromosomes. There was an obvious variation in the intensity of hybridization signals on different chromosomes, indicating that different centromeres have different amounts of CentC and CRM sequences. In some centromeres, the intensity of CentC signals differed from that of CRM signals and was free from overlapping. In T. dactyloides, only weak CentC and CRM signals were detected in the centromeric regions of most chromosomes, while in C. lacryma-jobi and S. bicolor only relatively strong or strong CRM signals primarily located in the centromeric regions were detected. This result indicates that CentC is highly conserved among the subspecies of Z. mays and the species of Zea, and has high conservation in Tripsacum, a genus that is most closely related to Zea, and CRM is conserved among the species of grass family either closely or distantly related to Zea.

  4. Widespread Positive Selection Drives Differentiation of Centromeric Proteins in the Drosophila melanogaster subgroup.

    Science.gov (United States)

    Beck, Emily A; Llopart, Ana

    2015-11-25

    Rapid evolution of centromeric satellite repeats is thought to cause compensatory amino acid evolution in interacting centromere-associated kinetochore proteins. Cid, a protein that mediates kinetochore/centromere interactions, displays particularly high amino acid turnover. Rapid evolution of both Cid and centromeric satellite repeats led us to hypothesize that the apparent compensatory evolution may extend to interacting partners in the Condensin I complex (i.e., SMC2, SMC4, Cap-H, Cap-D2, and Cap-G) and HP1s. Missense mutations in these proteins often result in improper centromere formation and aberrant chromosome segregation, thus selection for maintained function and coevolution among proteins of the complex is likely strong. Here, we report evidence of rapid evolution and recurrent positive selection in seven centromere-associated proteins in species of the Drosophila melanogaster subgroup, and further postulate that positive selection on these proteins could be a result of centromere drive and compensatory changes, with kinetochore proteins competing for optimal spindle attachment.

  5. A kinase-dependent role for Haspin in antagonizing Wapl and protecting mitotic centromere cohesion.

    Science.gov (United States)

    Liang, Cai; Chen, Qinfu; Yi, Qi; Zhang, Miao; Yan, Haiyan; Zhang, Bo; Zhou, Linli; Zhang, Zhenlei; Qi, Feifei; Ye, Sheng; Wang, Fangwei

    2017-11-14

    Sister-chromatid cohesion mediated by the cohesin complex is fundamental for precise chromosome segregation in mitosis. Through binding the cohesin subunit Pds5, Wapl releases the bulk of cohesin from chromosome arms in prophase, whereas centromeric cohesin is protected from Wapl until anaphase onset. Strong centromere cohesion requires centromeric localization of the mitotic histone kinase Haspin, which is dependent on the interaction of its non-catalytic N-terminus with Pds5B. It remains unclear how Haspin fully blocks the Wapl-Pds5B interaction at centromeres. Here, we show that the C-terminal kinase domain of Haspin (Haspin-KD) binds and phosphorylates the YSR motif of Wapl (Wapl-YSR), thereby directly inhibiting the YSR motif-dependent interaction of Wapl with Pds5B. Cells expressing a Wapl-binding-deficient mutant of Haspin or treated with Haspin inhibitors show centromeric cohesion defects. Phospho-mimetic mutation in Wapl-YSR prevents Wapl from binding Pds5B and releasing cohesin. Forced targeting Haspin-KD to centromeres partly bypasses the need for Haspin-Pds5B interaction in cohesion protection. Taken together, these results indicate a kinase-dependent role for Haspin in antagonizing Wapl and protecting centromeric cohesion in mitosis. © 2017 The Authors.

  6. Bub1 targeting to centromeres is sufficient for Sgo1 recruitment in the absence of kinetochores.

    Science.gov (United States)

    Williams, Samantha J; Abrieu, Ariane; Losada, Ana

    2017-03-01

    Centromeric chromatin containing the histone H3 variant centromere protein A (CENP-A) directs kinetochore assembly through a hierarchical binding of CENPs, starting with CENP-C and CENP-T. Centromeres are also the chromosomal regions where cohesion, mediated by cohesin, is most prominently maintained in mitosis. While most cohesin dissociates from chromosome arms in prophase, Shugoshin 1 (Sgo1) prevents this process at centromeres. Centromeric localization of Sgo1 depends on histone H2A phosphorylation by the kinase Bub1, but whether additional interactions with kinetochore components are required for Sgo1 recruitment is unclear. Using the Xenopus egg cell-free system, we here show that both CENP-C and CENP-T can independently drive centromeric accumulation of Sgo1 through recruitment of Bub1 to the KNL1, MIS12, NDC80 (KMN) network. The spindle assembly checkpoint (SAC) kinase Mps1 is also required for this pathway even in the absence of checkpoint signaling. Sgo1 recruitment is abolished in chromosomes lacking kinetochore components other than CENP-A. However, forced targeting of Bub1 to centromeres is sufficient to restore Sgo1 localization under this condition.

  7. High quality maize centromere 10 sequence reveals evidence of frequent recombination events

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    Thomas Kai Wolfgruber

    2016-03-01

    Full Text Available The ancestral centromeres of maize contain long stretches of the tandemly arranged CentC repeat. The abundance of tandem DNA repeats and centromeric retrotransposons (CR have presented a significant challenge to completely assembling centromeres using traditional sequencing methods. Here we report a nearly complete assembly of the 1.85 Mb maize centromere 10 from inbred B73 using PacBio technology and BACs from the reference genome project. The error rates estimated from overlapping BAC sequences are 7 x 10-6 and 5 x 10-5 for mismatches and indels, respectively. The number of gaps in the region covered by the reassembly was reduced from 140 in the reference genome to three. Three expressed genes are located between 92 and 477 kb of the inferred ancestral CentC cluster, which lies within the region of highest centromeric repeat density. The improved assembly increased the count of full-length centromeric retrotransposons from 5 to 55 and revealed a 22.7 kb segmental duplication that occurred approximately 121,000 years ago. Our analysis provides evidence of frequent recombination events in the form of partial retrotransposons, deletions within retrotransposons, chimeric retrotransposons, segmental duplications including higher order CentC repeats, a deleted CentC monomer, centromere-proximal inversions, and insertion of mitochondrial sequences. Double-strand DNA break (DSB repair is the most plausible mechanism for these events and may be the major driver of centromere repeat evolution and diversity. This repair appears to be mediated by microhomology, suggesting that tandem repeats may have evolved to facilitate the repair of frequent DSBs in centromeres.

  8. Rad51-Rad52 mediated maintenance of centromeric chromatin in Candida albicans.

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    Sreyoshi Mitra

    2014-04-01

    Full Text Available Specification of the centromere location in most eukaryotes is not solely dependent on the DNA sequence. However, the non-genetic determinants of centromere identity are not clearly defined. While multiple mechanisms, individually or in concert, may specify centromeres epigenetically, most studies in this area are focused on a universal factor, a centromere-specific histone H3 variant CENP-A, often considered as the epigenetic determinant of centromere identity. In spite of variable timing of its loading at centromeres across species, a replication coupled early S phase deposition of CENP-A is found in most yeast centromeres. Centromeres are the earliest replicating chromosomal regions in a pathogenic budding yeast Candida albicans. Using a 2-dimensional agarose gel electrophoresis assay, we identify replication origins (ORI7-LI and ORI7-RI proximal to an early replicating centromere (CEN7 in C. albicans. We show that the replication forks stall at CEN7 in a kinetochore dependent manner and fork stalling is reduced in the absence of the homologous recombination (HR proteins Rad51 and Rad52. Deletion of ORI7-RI causes a significant reduction in the stalled fork signal and an increased loss rate of the altered chromosome 7. The HR proteins, Rad51 and Rad52, have been shown to play a role in fork restart. Confocal microscopy shows declustered kinetochores in rad51 and rad52 mutants, which are evidence of kinetochore disintegrity. CENP-ACaCse4 levels at centromeres, as determined by chromatin immunoprecipitation (ChIP experiments, are reduced in absence of Rad51/Rad52 resulting in disruption of the kinetochore structure. Moreover, western blot analysis reveals that delocalized CENP-A molecules in HR mutants degrade in a similar fashion as in other kinetochore mutants described before. Finally, co-immunoprecipitation assays indicate that Rad51 and Rad52 physically interact with CENP-ACaCse4 in vivo. Thus, the HR proteins Rad51 and Rad52

  9. Unequivocal identification of the active and inactive centromere of a dicentric chromosome by simultaneous CENP-C immunofluorescence and FISH

    Energy Technology Data Exchange (ETDEWEB)

    Page, S.L.; Shaffer, L.G. [Baylor College of Medicine, Houston, TX (United States); Earnshaw, W.C. [Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States)] [and others

    1994-09-01

    There have been many reports of stable dicentric chromosomes resulting from translocations in humans. The stability of these chromosomes has been attributed to the inactivation of one centromere, yielding a functionally monocentric chromosome. We ascertained a patient with the karyotype 45,X/45,X,der(X)t(X;15)(Xpter{yields}Xq26::15p11{yields}15qter). The derivative chromosome was apparently dicentric by G-band analysis. A primary constriction at the X centromere and lack of a constriction corresponding to the 15 centromere suggested that the 15 centromere was inactive, while the X centromere remained active. Centromere Protein C(CENP-C) is normally present at all human centromeres and is localized to the inner kinetochore plate. Previous immunofluorescence studies of a stable isodicentric chromosome showed CENP-C to be present at the active centromere, while no staining was observed at the inactive centromere. By combining immunofluorescence detection of CENP-C and multi-color fluorescence in situ hybridization (FISH) with chromosome-specific {alpha} satellite DNA probes, we have unequivocally identified the active centromere in the (X;15) translocation. Metaphases were prepared by cytocentrifugation of hypotonically swelled lymphoblasts. Indirect immunofluorescence, performed using polyclonal rabbit antiserum raised against CENP-C, and FISH with {alpha}-satellite probes specific for the centromeres of chromosomes 15 (pTRA-20,pTRA-25) and X (DXZ1) revealed CENP-C immunofluorescence signals at the X {alpha}-satellite probe, with no CENP-C detected at the 15 centromere on the translocation in this cell line. This study is the first to demonstrate the specificity of CENP-C to the active centromere in a nonhomologous dicentric rearrangement and further establishes CENP-C as an essential component of a functional human centromere.

  10. Mislocalization of the Drosophila centromere-specific histone CIDpromotes formation of functional ectopic kinetochores

    Energy Technology Data Exchange (ETDEWEB)

    Heun, Patrick; Erhardt, Sylvia; Blower, Michael D.; Weiss,Samara; Skora, Andrew D.; Karpen, Gary H.

    2006-01-30

    The centromere-specific histone variant CENP-A (CID in Drosophila) is a structural and functional foundation for kinetochore formation and chromosome segregation. Here, we show that overexpressed CID is mislocalized into normally non-centromeric regions in Drosophila tissue culture cells and animals. Analysis of mitoses in living and fixed cells reveals that mitotic delays, anaphase bridges, chromosome fragmentation, and cell and organismal lethality are all direct consequences of CID mislocalization. In addition, proteins that are normally restricted to endogenous kinetochores assemble at a subset of ectopic CID incorporation regions. The presence of microtubule motors and binding proteins, spindle attachments, and aberrant chromosome morphologies demonstrate that these ectopic kinetochores are functional. We conclude that CID mislocalization promotes formation of ectopic centromeres and multicentric chromosomes, which causes chromosome missegregation, aneuploidy, and growth defects. Thus, CENP-A mislocalization is one possible mechanism for genome instability during cancer progression, as well as centromere plasticity during evolution.

  11. The nucleoplasmin homolog NLP mediates centromere clustering and anchoring to the nucleolus.

    Science.gov (United States)

    Padeken, Jan; Mendiburo, María José; Chlamydas, Sarantis; Schwarz, Hans-Jürgen; Kremmer, Elisabeth; Heun, Patrick

    2013-04-25

    Centromere clustering during interphase is a phenomenon known to occur in many different organisms and cell types, yet neither the factors involved nor their physiological relevance is well understood. Using Drosophila tissue culture cells and flies, we identified a network of proteins, including the nucleoplasmin-like protein (NLP), the insulator protein CTCF, and the nucleolus protein Modulo, to be essential for the positioning of centromeres. Artificial targeting further demonstrated that NLP and CTCF are sufficient for clustering, while Modulo serves as the anchor to the nucleolus. Centromere clustering was found to depend on centric chromatin rather than specific DNA sequences. Moreover, unclustering of centromeres results in the spatial destabilization of pericentric heterochromatin organization, leading to partial defects in the silencing of repetitive elements, defects during chromosome segregation, and genome instability. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Characterisation of centromere (kinetochore) antigen reactive with sera of patients with a scleroderma variant (CREST syndrome).

    Science.gov (United States)

    Nishikai, M; Okano, Y; Yamashita, H; Watanabe, M

    1984-01-01

    Anticentromere (kinetochore) antibody is the marker antibody in CREST syndrome, but the precise molecular composition of the partner antigen has been poorly defined. This report describes for the first time a procedure for the successful extraction and biochemical characterisation of the centromere antigen molecule. The centromere antigen was extracted with 4M NaCl solution. The molecular weight of the partner antigen of the centromere antibody was determined to be 70 000 daltons by the SDS-PAGE and immunoblotting methods. A Sephacryl S-300 column experiment confirmed these results. Centromere antigenic activity was preserved at pHs between 3 and 11 and was resistant to three enzymes, trypsin, RNase, and DNase. Images PMID:6524984

  13. Analysis of ParB-centromere interactions by multiplex SPR imaging reveals specific patterns for binding ParB in six centromeres of Burkholderiales chromosomes and plasmids.

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    Flavien Pillet

    Full Text Available Bacterial centromeres-also called parS, are cis-acting DNA sequences which, together with the proteins ParA and ParB, are involved in the segregation of chromosomes and plasmids. The specific binding of ParB to parS nucleates the assembly of a large ParB/DNA complex from which ParA-the motor protein, segregates the sister replicons. Closely related families of partition systems, called Bsr, were identified on the chromosomes and large plasmids of the multi-chromosomal bacterium Burkholderia cenocepacia and other species from the order Burkholeriales. The centromeres of the Bsr partition families are 16 bp palindromes, displaying similar base compositions, notably a central CG dinucleotide. Despite centromeres bind the cognate ParB with a narrow specificity, weak ParB-parS non cognate interactions were nevertheless detected between few Bsr partition systems of replicons not belonging to the same genome. These observations suggested that Bsr partition systems could have a common ancestry but that evolution mostly erased the possibilities of cross-reactions between them, in particular to prevent replicon incompatibility. To detect novel similarities between Bsr partition systems, we have analyzed the binding of six Bsr parS sequences and a wide collection of modified derivatives, to their cognate ParB. The study was carried out by Surface Plasmon Resonance imaging (SPRi mulitplex analysis enabling a systematic survey of each nucleotide position within the centromere. We found that in each parS some positions could be changed while maintaining binding to ParB. Each centromere displays its own pattern of changes, but some positions are shared more or less widely. In addition from these changes we could speculate evolutionary links between these centromeres.

  14. Interplay between synaptonemal complex, homologous recombination, and centromeres during mammalian meiosis.

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    Huanyu Qiao

    2012-06-01

    Full Text Available The intimate synapsis of homologous chromosome pairs (homologs by synaptonemal complexes (SCs is an essential feature of meiosis. In many organisms, synapsis and homologous recombination are interdependent: recombination promotes SC formation and SCs are required for crossing-over. Moreover, several studies indicate that initiation of SC assembly occurs at sites where crossovers will subsequently form. However, recent analyses in budding yeast and fruit fly imply a special role for centromeres in the initiation of SC formation. In addition, in budding yeast, persistent SC-dependent centromere-association facilitates the disjunction of chromosomes that have failed to become connected by crossovers. Here, we examine the interplay between SCs, recombination, and centromeres in a mammal. In mouse spermatocytes, centromeres do not serve as SC initiation sites and are invariably the last regions to synapse. However, centromeres are refractory to de-synapsis during diplonema and remain associated by short SC fragments. Since SC-dependent centromere association is lost before diakinesis, a direct role in homolog segregation seems unlikely. However, post-SC disassembly, we find evidence of inter-centromeric connections that could play a more direct role in promoting homolog biorientation and disjunction. A second class of persistent SC fragments is shown to be crossover-dependent. Super-resolution structured-illumination microscopy (SIM reveals that these structures initially connect separate homolog axes and progressively diminish as chiasmata form. Thus, DNA crossing-over (which occurs during pachynema and axis remodeling appear to be temporally distinct aspects of chiasma formation. SIM analysis of the synapsis and crossover-defective mutant Sycp1⁻/⁻ implies that SCs prevent unregulated fusion of homolog axes. We propose that SC fragments retained during diplonema stabilize nascent bivalents and help orchestrate local chromosome reorganization

  15. Centromere Locations in Brassica A and C Genomes Revealed Through Half-Tetrad Analysis.

    Science.gov (United States)

    Mason, Annaliese S; Rousseau-Gueutin, Mathieu; Morice, Jérôme; Bayer, Philipp E; Besharat, Naghmeh; Cousin, Anouska; Pradhan, Aneeta; Parkin, Isobel A P; Chèvre, Anne-Marie; Batley, Jacqueline; Nelson, Matthew N

    2016-02-01

    Locating centromeres on genome sequences can be challenging. The high density of repetitive elements in these regions makes sequence assembly problematic, especially when using short-read sequencing technologies. It can also be difficult to distinguish between active and recently extinct centromeres through sequence analysis. An effective solution is to identify genetically active centromeres (functional in meiosis) by half-tetrad analysis. This genetic approach involves detecting heterozygosity along chromosomes in segregating populations derived from gametes (half-tetrads). Unreduced gametes produced by first division restitution mechanisms comprise complete sets of nonsister chromatids. Along these chromatids, heterozygosity is maximal at the centromeres, and homologous recombination events result in homozygosity toward the telomeres. We genotyped populations of half-tetrad-derived individuals (from Brassica interspecific hybrids) using a high-density array of physically anchored SNP markers (Illumina Brassica 60K Infinium array). Mapping the distribution of heterozygosity in these half-tetrad individuals allowed the genetic mapping of all 19 centromeres of the Brassica A and C genomes to the reference Brassica napus genome. Gene and transposable element density across the B. napus genome were also assessed and corresponded well to previously reported genetic map positions. Known centromere-specific sequences were located in the reference genome, but mostly matched unanchored sequences, suggesting that the core centromeric regions may not yet be assembled into the pseudochromosomes of the reference genome. The increasing availability of genetic markers physically anchored to reference genomes greatly simplifies the genetic and physical mapping of centromeres using half-tetrad analysis. We discuss possible applications of this approach, including in species where half-tetrads are currently difficult to isolate. Copyright © 2016 by the Genetics Society of America.

  16. Recurrent Gene Duplication Leads to Diverse Repertoires of Centromeric Histones in Drosophila Species.

    Science.gov (United States)

    Kursel, Lisa E; Malik, Harmit S

    2017-06-01

    Despite their essential role in the process of chromosome segregation in most eukaryotes, centromeric histones show remarkable evolutionary lability. Not only have they been lost in multiple insect lineages, but they have also undergone gene duplication in multiple plant lineages. Based on detailed study of a handful of model organisms including Drosophila melanogaster, centromeric histone duplication is considered to be rare in animals. Using a detailed phylogenomic study, we find that Cid, the centromeric histone gene, has undergone at least four independent gene duplications during Drosophila evolution. We find duplicate Cid genes in D. eugracilis (Cid2), in the montium species subgroup (Cid3, Cid4) and in the entire Drosophila subgenus (Cid5). We show that Cid3, Cid4, and Cid5 all localize to centromeres in their respective species. Some Cid duplicates are primarily expressed in the male germline. With rare exceptions, Cid duplicates have been strictly retained after birth, suggesting that they perform nonredundant centromeric functions, independent from the ancestral Cid. Indeed, each duplicate encodes a distinct N-terminal tail, which may provide the basis for distinct protein-protein interactions. Finally, we show some Cid duplicates evolve under positive selection whereas others do not. Taken together, our results support the hypothesis that Drosophila Cid duplicates have subfunctionalized. Thus, these gene duplications provide an unprecedented opportunity to dissect the multiple roles of centromeric histones. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  17. Human condensin function is essential for centromeric chromatin assembly and proper sister kinetochore orientation.

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    Alexander Samoshkin

    Full Text Available Condensins I and II in vertebrates are essential ATP-dependent complexes necessary for chromosome condensation in mitosis. Condensins depletion is known to perturb structure and function of centromeres, however the mechanism of this functional link remains elusive. Depletion of condensin activity is now shown to result in a significant loss of loading of CENP-A, the histone H3 variant found at active centromeres and the proposed epigenetic mark of centromere identity. Absence of condensins and/or CENP-A insufficiency produced a specific kinetochore defect, such that a functional mitotic checkpoint cannot prevent chromosome missegregation resulting from improper attachment of sister kinetochores to spindle microtubules. Spindle microtubule-dependent deformation of both inner kinetochores and the HEC1/Ndc80 microtubule-capturing module, then results in kinetochore separation from the Aurora B pool and ensuing reduced kinase activity at centromeres. Moreover, recovery from mitosis-inhibition by monastrol revealed a high incidence of merotelic attachment that was nearly identical with condensin depletion, Aurora B inactivation, or both, indicating that the Aurora B dysfunction is the key defect leading to chromosome missegregation in condensin-depleted cells. Thus, beyond a requirement for global chromosome condensation, condensins play a pivotal role in centromere assembly, proper spatial positioning of microtubule-capturing modules and positioning complexes of the inner centromere versus kinetochore plates.

  18. Telomere-Centromere-Driven Genomic Instability Contributes to Karyotype Evolution in a Mouse Model of Melanoma

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    Amanda Gonçalves dos Santos Silva

    2010-01-01

    Full Text Available Aneuploidy and chromosomal instability (CIN are hallmarks of most solid tumors. These alterations may result from inaccurate chromosomal segregation during mitosis, which can occur through several mechanisms including defective telomere metabolism, centrosome amplification, dysfunctional centromeres, and/or defective spindle checkpoint control. In this work, we used an in vitro murine melanoma model that uses a cellular adhesion blockade as a transforming factor to characterize telomeric and centromeric alterations that accompany melanocyte transformation. To study the timing of the occurrence of telomere shortening in this transformation model, we analyzed the profile of telomere length by quantitative fluorescent in situ hybridization and found that telomere length significantly decreased as additional rounds of cell adhesion blockages were performed. Together with it, an increase in telomere-free ends and complex karyotypic aberrations were also found, which include Robertsonian fusions in 100% of metaphases of the metastatic melanoma cells. These findings are in agreement with the idea that telomere length abnormalities seem to be one of the earliest genetic alterations acquired in the multistep process of malignant transformation and that telomere abnormalities result in telomere aggregation, breakage-bridge-fusion cycles, and CIN. Another remarkable feature of this model is the abundance of centromeric instability manifested as centromere fragments and centromeric fusions. Taken together, our results illustrate for this melanoma model CIN with a structural signature of centromere breakage and telomeric loss.

  19. Centromeric DNA replication reconstitution reveals DNA loops and ATR checkpoint suppression.

    Science.gov (United States)

    Aze, Antoine; Sannino, Vincenzo; Soffientini, Paolo; Bachi, Angela; Costanzo, Vincenzo

    2016-06-01

    Half of the human genome is made up of repetitive DNA. However, mechanisms underlying replication of chromosome regions containing repetitive DNA are poorly understood. We reconstituted replication of defined human chromosome segments using bacterial artificial chromosomes in Xenopus laevis egg extract. Using this approach we characterized the chromatin assembly and replication dynamics of centromeric alpha-satellite DNA. Proteomic analysis of centromeric chromatin revealed replication-dependent enrichment of a network of DNA repair factors including the MSH2-6 complex, which was required for efficient centromeric DNA replication. However, contrary to expectations, the ATR-dependent checkpoint monitoring DNA replication fork arrest could not be activated on highly repetitive DNA due to the inability of the single-stranded DNA binding protein RPA to accumulate on chromatin. Electron microscopy of centromeric DNA and supercoil mapping revealed the presence of topoisomerase I-dependent DNA loops embedded in a protein matrix enriched for SMC2-4 proteins. This arrangement suppressed ATR signalling by preventing RPA hyper-loading, facilitating replication of centromeric DNA. These findings have important implications for our understanding of repetitive DNA metabolism and centromere organization under normal and stressful conditions.

  20. Locus control regions

    National Research Council Canada - National Science Library

    Li, Qiliang; Peterson, Kenneth R; Fang, Xiangdong; Stamatoyannopoulos, George

    2002-01-01

    Locus control regions (LCRs) are operationally defined by their ability to enhance the expression of linked genes to physiological levels in a tissue-specific and copy number-dependent manner at ectopic chromatin sites...

  1. Molecular architecture of classical cytological landmarks: Centromeres and telomeres

    Energy Technology Data Exchange (ETDEWEB)

    Meyne, J.

    1994-11-01

    Both the human telomere repeat and the pericentromeric repeat sequence (GGAAT)n were isolated based on evolutionary conservation. Their isolation was based on the premise that chromosomal features as structurally and functionally important as telomeres and centromeres should be highly conserved. Both sequences were isolated by high stringency screening of a human repetitive DNA library with rodent repetitive DNA. The pHuR library (plasmid Human Repeat) used for this project was enriched for repetitive DNA by using a modification of the standard DNA library preparation method. Usually DNA for a library is cut with restriction enzymes, packaged, infected, and the library is screened. A problem with this approach is that many tandem repeats don`t have any (or many) common restriction sites. Therefore, many of the repeat sequences will not be represented in the library because they are not restricted to a viable length for the vector used. To prepare the pHuR library, human DNA was mechanically sheared to a small size. These relatively short DNA fragments were denatured and then renatured to C{sub o}t 50. Theoretically only repetitive DNA sequences should renature under C{sub o}t 50 conditions. The single-stranded regions were digested using S1 nuclease, leaving the double-stranded, renatured repeat sequences.

  2. Differential Regulation of Strand-Specific Transcripts from Arabidopsis Centromeric Satellite Repeats.

    Directory of Open Access Journals (Sweden)

    2005-12-01

    Full Text Available Centromeres interact with the spindle apparatus to enable chromosome disjunction and typically contain thousands of tandemly arranged satellite repeats interspersed with retrotransposons. While their role has been obscure, centromeric repeats are epigenetically modified and centromere specification has a strong epigenetic component. In the yeast Schizosaccharomyces pombe, long heterochromatic repeats are transcribed and contribute to centromere function via RNA interference (RNAi. In the higher plant Arabidopsis thaliana, as in mammalian cells, centromeric satellite repeats are short (180 base pairs, are found in thousands of tandem copies, and are methylated. We have found transcripts from both strands of canonical, bulk Arabidopsis repeats. At least one subfamily of 180-base pair repeats is transcribed from only one strand and regulated by RNAi and histone modification. A second subfamily of repeats is also silenced, but silencing is lost on both strands in mutants in the CpG DNA methyltransferase MET1, the histone deacetylase HDA6/SIL1, or the chromatin remodeling ATPase DDM1. This regulation is due to transcription from Athila2 retrotransposons, which integrate in both orientations relative to the repeats, and differs between strains of Arabidopsis. Silencing lost in met1 or hda6 is reestablished in backcrosses to wild-type, but silencing lost in RNAi mutants and ddm1 is not. Twenty-four-nucleotide small interfering RNAs from centromeric repeats are retained in met1 and hda6, but not in ddm1, and may have a role in this epigenetic inheritance. Histone H3 lysine-9 dimethylation is associated with both classes of repeats. We propose roles for transcribed repeats in the epigenetic inheritance and evolution of centromeres.

  3. Analysis of ParB-centromere interactions by multiplex SPR imaging reveals specific patterns for binding ParB in six centromeres of Burkholderiales chromosomes and plasmids

    Science.gov (United States)

    Pillet, Flavien; Passot, Fanny Marie

    2017-01-01

    Bacterial centromeres–also called parS, are cis-acting DNA sequences which, together with the proteins ParA and ParB, are involved in the segregation of chromosomes and plasmids. The specific binding of ParB to parS nucleates the assembly of a large ParB/DNA complex from which ParA—the motor protein, segregates the sister replicons. Closely related families of partition systems, called Bsr, were identified on the chromosomes and large plasmids of the multi-chromosomal bacterium Burkholderia cenocepacia and other species from the order Burkholeriales. The centromeres of the Bsr partition families are 16 bp palindromes, displaying similar base compositions, notably a central CG dinucleotide. Despite centromeres bind the cognate ParB with a narrow specificity, weak ParB-parS non cognate interactions were nevertheless detected between few Bsr partition systems of replicons not belonging to the same genome. These observations suggested that Bsr partition systems could have a common ancestry but that evolution mostly erased the possibilities of cross-reactions between them, in particular to prevent replicon incompatibility. To detect novel similarities between Bsr partition systems, we have analyzed the binding of six Bsr parS sequences and a wide collection of modified derivatives, to their cognate ParB. The study was carried out by Surface Plasmon Resonance imaging (SPRi) mulitplex analysis enabling a systematic survey of each nucleotide position within the centromere. We found that in each parS some positions could be changed while maintaining binding to ParB. Each centromere displays its own pattern of changes, but some positions are shared more or less widely. In addition from these changes we could speculate evolutionary links between these centromeres. PMID:28562673

  4. Prognostic relevance of Centromere protein H expression in esophageal carcinoma

    Science.gov (United States)

    Guo, Xian-Zhi; Zhang, Ge; Wang, Jun-Ye; Liu, Wan-Li; Wang, Fang; Dong, Ju-Qin; Xu, Li-Hua; Cao, Jing-Yan; Song, Li-Bing; Zeng, Mu-Sheng

    2008-01-01

    Background Many kinetochore proteins have been shown to be associated with human cancers. The aim of the present study was to clarify the expression of Centromere protein H (CENP-H), one of the fundamental components of the human active kinetochore, in esophageal carcinoma and its correlation with clinicopathological features. Methods We examined the expression of CENP-H in immortalized esophageal epithelial cells as well as in esophageal carcinoma cells, and in 12 cases of esophageal carcinoma tissues and the paired normal esophageal tissues by RT-PCR and Western blot analysis. In addition, we analyzed CENP-H protein expression in 177 clinicopathologically characterized esophageal carcinoma cases by immunohistochemistry. Statistical analyses were applied to test for prognostic and diagnostic associations. Results The level of CENP-H mRNA and protein were higher in the immortalized cells, cancer cell lines and most cancer tissues than in normal control tissues. Immunohistochemistry showed that CENP-H was expressed in 127 of 171 ESCC cases (74.3%) and in 3 of 6 esophageal adenocarcinoma cases (50%). Statistical analysis of ESCC cases showed that there was a significant difference of CENP-H expression in patients categorized according to gender (P = 0.013), stage (P = 0.023) and T classification (P = 0.019). Patients with lower CENP-H expression had longer overall survival time than those with higher CENP-H expression. Multivariate analysis suggested that CENP-H expression was an independent prognostic marker for esophageal carcinoma patients. A prognostic value of CENP-H was also found in the subgroup of T3~T4 and N0 tumor classification. Conclusion Our results suggest that CENP-H protein is a valuable marker of esophageal carcinoma progression. CENP-H might be used as a valuable prognostic marker for esophageal carcinoma patients. PMID:18700042

  5. The Role of Dicentric Chromosome Formation and Secondary Centromere Deletion in the Evolution of Myeloid Malignancy

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    Ruth N. MacKinnon

    2011-01-01

    Full Text Available Dicentric chromosomes have been identified as instigators of the genome instability associated with cancer, but this instability is often resolved by one of a number of different secondary events. These include centromere inactivation, inversion, and intercentromeric deletion. Deletion or excision of one of the centromeres may be a significant occurrence in myeloid malignancy and other malignancies but has not previously been widely recognized, and our reports are the first describing centromere deletion in cancer cells. We review what is known about dicentric chromosomes and the mechanisms by which they can undergo stabilization in both constitutional and cancer genomes. The failure to identify centromere deletion in cancer cells until recently can be partly explained by the standard approaches to routine diagnostic cancer genome analysis, which do not identify centromeres in the context of chromosome organization. This hitherto hidden group of primary dicentric, secondary monocentric chromosomes, together with other unrecognized dicentric chromosomes, points to a greater role for dicentric chromosomes in cancer initiation and progression than is generally acknowledged. We present a model that predicts and explains a significant role for dicentric chromosomes in the formation of unbalanced translocations in malignancy.

  6. DNA binding of centromere protein C (CENPC is stabilized by single-stranded RNA.

    Directory of Open Access Journals (Sweden)

    Yaqing Du

    2010-02-01

    Full Text Available Centromeres are the attachment points between the genome and the cytoskeleton: centromeres bind to kinetochores, which in turn bind to spindles and move chromosomes. Paradoxically, the DNA sequence of centromeres has little or no role in perpetuating kinetochores. As such they are striking examples of genetic information being transmitted in a manner that is independent of DNA sequence (epigenetically. It has been found that RNA transcribed from centromeres remains bound within the kinetochore region, and this local population of RNA is thought to be part of the epigenetic marking system. Here we carried out a genetic and biochemical study of maize CENPC, a key inner kinetochore protein. We show that DNA binding is conferred by a localized region 122 amino acids long, and that the DNA-binding reaction is exquisitely sensitive to single-stranded RNA. Long, single-stranded nucleic acids strongly promote the binding of CENPC to DNA, and the types of RNAs that stabilize DNA binding match in size and character the RNAs present on kinetochores in vivo. Removal or replacement of the binding module with HIV integrase binding domain causes a partial delocalization of CENPC in vivo. The data suggest that centromeric RNA helps to recruit CENPC to the inner kinetochore by altering its DNA binding characteristics.

  7. APC/C-Cdc20 mediates deprotection of centromeric cohesin at meiosis II in yeast.

    Science.gov (United States)

    Jonak, Katarzyna; Zagoriy, Ievgeniia; Oz, Tugce; Graf, Peter; Rojas, Julie; Mengoli, Valentina; Zachariae, Wolfgang

    2017-06-18

    Cells undergoing meiosis produce haploid gametes through one round of DNA replication followed by 2 rounds of chromosome segregation. This requires that cohesin complexes, which establish sister chromatid cohesion during S phase, are removed in a stepwise manner. At meiosis I, the separase protease triggers the segregation of homologous chromosomes by cleaving cohesin's Rec8 subunit on chromosome arms. Cohesin persists at centromeres because the PP2A phosphatase, recruited by the shugoshin protein, dephosphorylates Rec8 and thereby protects it from cleavage. While chromatids disjoin upon cleavage of centromeric Rec8 at meiosis II, it was unclear how and when centromeric Rec8 is liberated from its protector PP2A. One proposal is that bipolar spindle forces separate PP2A from Rec8 as cells enter metaphase II. We show here that sister centromere biorientation is not sufficient to "deprotect" Rec8 at meiosis II in yeast. Instead, our data suggest that the ubiquitin-ligase APC/C(Cdc20) removes PP2A from centromeres by targeting for degradation the shugoshin Sgo1 and the kinase Mps1. This implies that Rec8 remains protected until entry into anaphase II when it is phosphorylated concurrently with the activation of separase. Here, we provide further support for this model and speculate on its relevance to mammalian oocytes.

  8. Replicating centromeric chromatin: Spatial and temporal control of CENP-A assembly

    Energy Technology Data Exchange (ETDEWEB)

    Nechemia-Arbely, Yael; Fachinetti, Daniele; Cleveland, Don W., E-mail: dcleveland@ucsd.edu

    2012-07-15

    The centromere is the fundamental unit for insuring chromosome inheritance. This complex region has a distinct type of chromatin in which histone H3 is replaced by a structurally different homologue identified in humans as CENP-A. In metazoans, specific DNA sequences are neither required nor sufficient for centromere identity. Rather, an epigenetic mark comprised of CENP-A containing chromatin is thought to be the major determinant of centromere identity. In this view, CENP-A deposition and chromatin assembly are fundamental processes for the maintenance of centromeric identity across mitotic and meiotic divisions. Several lines of evidence support CENP-A deposition in metazoans occurring at only one time in the cell cycle. Such cell cycle-dependent loading of CENP-A is found in divergent species from human to fission yeast, albeit with differences in the cell cycle point at which CENP-A is assembled. Cell cycle dependent CENP-A deposition requires multiple assembly factors for its deposition and maintenance. This review discusses the regulation of new CENP-A deposition and its relevance to centromere identity and inheritance.

  9. Species-specific shifts in centromere sequence composition are coincident with breakpoint reuse in karyotypically divergent lineages

    Science.gov (United States)

    Bulazel, Kira V; Ferreri, Gianni C; Eldridge, Mark DB; O'Neill, Rachel J

    2007-01-01

    Background It has been hypothesized that rapid divergence in centromere sequences accompanies rapid karyotypic change during speciation. However, the reuse of breakpoints coincident with centromeres in the evolution of divergent karyotypes poses a potential paradox. In distantly related species where the same centromere breakpoints are used in the independent derivation of karyotypes, centromere-specific sequences may undergo convergent evolution rather than rapid sequence divergence. To determine whether centromere sequence composition follows the phylogenetic history of species evolution or patterns of convergent breakpoint reuse through chromosome evolution, we examined the phylogenetic trajectory of centromere sequences within a group of karyotypically diverse mammals, macropodine marsupials (wallabies, wallaroos and kangaroos). Results The evolution of three classes of centromere sequences across nine species within the genus Macropus (including Wallabia) were compared with the phylogenetic history of a mitochondrial gene, Cytochrome b (Cyt b), a nuclear gene, selenocysteine tRNA (TRSP), and the chromosomal histories of the syntenic blocks that define the different karyotype arrangements. Convergent contraction or expansion of predominant satellites is found to accompany specific karyotype rearrangements. The phylogenetic history of these centromere sequences includes the convergence of centromere composition in divergent species through convergent breakpoint reuse between syntenic blocks. Conclusion These data support the 'library hypothesis' of centromere evolution within this genus as each species possesses all three satellites yet each species has experienced differential expansion and contraction of individual classes. Thus, we have identified a correlation between the evolution of centromere satellite sequences, the reuse of syntenic breakpoints, and karyotype convergence in the context of a gene-based phylogeny. PMID:17708770

  10. Alcohol Locus of Control.

    Science.gov (United States)

    Johnson, Patrick B.; Reszka, Diane

    Research has shown that differences in perceived control can influence drinking behavior and alcoholic rehabilitation. This study examined the viability of an alcohol-specific locus of control scale. Undergraduate students (41 male and 40 female) completed a demographic questionnaire assessing age, sex, ethnicity, and drinking frequency; Rotter's…

  11. Somatic association of telocentric chromosomes carrying homologous centromeres in common wheat.

    Science.gov (United States)

    Mello-Sampayo, T

    1973-01-01

    Measurements of distances between telocentric chromosomes, either homologous or representing the opposite arms of a metacentric chromosome (complementary telocentrics), were made at metaphase in root tip cells of common wheat carrying two homologous pairs of complementary telocentrics of chromosome 1 B or 6 B (double ditelosomic 1 B or 6 B). The aim was to elucidate the relative locations of the telocentric chromosomes within the cell. The data obtained strongly suggest that all four telocentrics of chromosome 1 B or 6 B are spacially and simultaneously co-associated. In plants carrying two complementary (6 B (S) and 6 B (L)) and a non-related (5 B (L)) telocentric, only the complementary chromosomes were found to be somatically associated. It is thought, therefore, that the somatic association of chromosomes may involve more than two chromosomes in the same association and, since complementary telocentrics are as much associated as homologous, that the homology between centromeres (probably the only homologous region that exists between complementary telocentrics) is a very important condition for somatic association of chromosomes. The spacial arrangement of chromosomes was studied at anaphase and prophase and the polar orientation of chromosomes at prophase was found to resemble anaphase orientation. This was taken as good evidence for the maintenance of the chromosome arrangement - the Rabl orientation - and of the peripheral location of the centromere and its association with the nuclear membrane. Within this general arrangement homologous telocentric chromosomes were frequently seen to have their centromeres associated or directed towards each other. The role of the centromere in somatic association as a spindle fibre attachment and chromosome binder is discussed. It is suggested that for non-homologous chromosomes to become associated in root tips, the only requirement needed should be the homology of centromeres such as exists between complementary

  12. Meiosis-Specific Loading of the Centromere-Specific Histone CENH3 in Arabidopsis thaliana

    Science.gov (United States)

    Ravi, Maruthachalam; Shibata, Fukashi; Ramahi, Joseph S.; Nagaki, Kiyotaka; Chen, Changbin; Murata, Minoru; Chan, Simon W. L.

    2011-01-01

    Centromere behavior is specialized in meiosis I, so that sister chromatids of homologous chromosomes are pulled toward the same side of the spindle (through kinetochore mono-orientation) and chromosome number is reduced. Factors required for mono-orientation have been identified in yeast. However, comparatively little is known about how meiotic centromere behavior is specialized in animals and plants that typically have large tandem repeat centromeres. Kinetochores are nucleated by the centromere-specific histone CENH3. Unlike conventional histone H3s, CENH3 is rapidly evolving, particularly in its N-terminal tail domain. Here we describe chimeric variants of CENH3 with alterations in the N-terminal tail that are specifically defective in meiosis. Arabidopsis thaliana cenh3 mutants expressing a GFP-tagged chimeric protein containing the H3 N-terminal tail and the CENH3 C-terminus (termed GFP-tailswap) are sterile because of random meiotic chromosome segregation. These defects result from the specific depletion of GFP-tailswap protein from meiotic kinetochores, which contrasts with its normal localization in mitotic cells. Loss of the GFP-tailswap CENH3 variant in meiosis affects recruitment of the essential kinetochore protein MIS12. Our findings suggest that CENH3 loading dynamics might be regulated differently in mitosis and meiosis. As further support for our hypothesis, we show that GFP-tailswap protein is recruited back to centromeres in a subset of pollen grains in GFP-tailswap once they resume haploid mitosis. Meiotic recruitment of the GFP-tailswap CENH3 variant is not restored by removal of the meiosis-specific cohesin subunit REC8. Our results reveal the existence of a specialized loading pathway for CENH3 during meiosis that is likely to involve the hypervariable N-terminal tail. Meiosis-specific CENH3 dynamics may play a role in modulating meiotic centromere behavior. PMID:21695238

  13. Mps1 kinase-dependent Sgo2 centromere localisation mediates cohesin protection in mouse oocyte meiosis I

    NARCIS (Netherlands)

    Yakoubi, W. El; Buffin, E.; Cladiere, D.; Gryaznova, Y.; Berenguer, I.; Touati, S.A.; Gomez, R.; Suja, J.A.; Deursen, J.M.A. van; Wassmann, K.

    2017-01-01

    A key feature of meiosis is the step-wise removal of cohesin, the protein complex holding sister chromatids together, first from arms in meiosis I and then from the centromere region in meiosis II. Centromeric cohesin is protected by Sgo2 from Separase-mediated cleavage, in order to maintain sister

  14. Mps1 kinase-dependent Sgo2 centromere localisation mediates cohesin protection in mouse oocyte meiosis I.

    Science.gov (United States)

    El Yakoubi, Warif; Buffin, Eulalie; Cladière, Damien; Gryaznova, Yulia; Berenguer, Inés; Touati, Sandra A; Gómez, Rocío; Suja, José A; van Deursen, Jan M; Wassmann, Katja

    2017-09-25

    A key feature of meiosis is the step-wise removal of cohesin, the protein complex holding sister chromatids together, first from arms in meiosis I and then from the centromere region in meiosis II. Centromeric cohesin is protected by Sgo2 from Separase-mediated cleavage, in order to maintain sister chromatids together until their separation in meiosis II. Failures in step-wise cohesin removal result in aneuploid gametes, preventing the generation of healthy embryos. Here, we report that kinase activities of Bub1 and Mps1 are required for Sgo2 localisation to the centromere region. Mps1 inhibitor-treated oocytes are defective in centromeric cohesin protection, whereas oocytes devoid of Bub1 kinase activity, which cannot phosphorylate H2A at T121, are not perturbed in cohesin protection as long as Mps1 is functional. Mps1 and Bub1 kinase activities localise Sgo2 in meiosis I preferentially to the centromere and pericentromere respectively, indicating that Sgo2 at the centromere is required for protection.In meiosis I centromeric cohesin is protected by Sgo2 from Separase-mediated cleavage ensuring that sister chromatids are kept together until their separation in meiosis II. Here the authors demonstrate that Bub1 and Mps1 kinase activities are required for Sgo2 localisation to the centromere region.

  15. Physical Characterization of human centromeric regions using transformation-associated recombination cloning technology

    Energy Technology Data Exchange (ETDEWEB)

    Vladimir Larionov, Ph D

    2007-06-05

    A special interest in the organization of human centromeric DNA was stimulated a few years ago when two independent groups succeeded in reconstituting a functional human centromere, using constructs carrying centromere-specific alphoid DNA arrays. This work demonstrated the importance of DNA components in mammalian centromeres and opened a way for studying the structural requirements for de novo kinetochore formation and for construction of human artificial chromosomes (HACs) with therapeutic potential. To elucidate the structural requirements for formation of HACs with a functional kinetochore, we developed a new method for cloning of large DNA fragments for human centromeric regions that can be used as a substrate for HAC formation. This method exploits in vivo recombination in yeast (TAR cloning). In addition, a new strategy for the construction of alphoid DNA arrays was developed in our lab. The strategy involves the construction of uniform or hybrid synthetic alphoid DNA arrays by the RCA-TAR technique. This technique comprises two steps: rolling circle amplification of an alphoid DNA dimer and subsequent assembling of the amplified fragments by in vivo homologous recombination in yeast (Figure 1). Using this system, we constructed a set of different synthetic alphoid DNA arrays with a predetermined sequence varying in size from 30 to 140 kb and demonstrated that some of the arrays are competent in HAC formation. Because any nucleotide can be changed in a dimer before its amplification, this new technique is optimal for identifying the structural requirements for de novo kinetochore formation in HACs. Moreover, the technique makes possible to introduce into alphoid DNA arrays recognition sites for DNA-binding proteins. We have made the following progress on the studying of human centromeric regions using transformation-associated recombination cloning technology: i) minimal size of alphoid DNA array required for de novo kinetochore formation was estimated; ii

  16. Multilocus half-tetrad analysis and centromere mapping in citrus: evidence of SDR mechanism for 2n megagametophyte production and partial chiasma interference in mandarin cv 'Fortune'.

    Science.gov (United States)

    Cuenca, J; Froelicher, Y; Aleza, P; Juárez, J; Navarro, L; Ollitrault, P

    2011-10-01

    The genetic structure of 2n gametes and, particularly, the parental heterozygosity restitution at each locus depends on the meiotic process by which they originated, with first-division restitution and second-division restitution (SDR) being the two major mechanisms. The origin of 2n gametes in citrus is still controversial, although sexual polyploidisation is widely used for triploid seedless cultivar development. In this study, we report the analysis of 2n gametes of mandarin cv 'Fortune' by genotyping 171 triploid hybrids with 35 simple sequence repeat markers. The microsatellite DNA allele counting-peak ratios method for allele-dosage evaluation proved highly efficient in segregating triploid progenies and allowed half-tetrad analysis (HTA) by inferring the 2n gamete allelic configuration. All 2n gametes arose from the female genitor. The observed maternal heterozygosity restitution varied between 10 and 82%, depending on the locus, thus SDR appears to be the mechanism underlying 2n gamete production in mandarin cv 'Fortune'. A new method to locate the centromere, based on the best fit between observed heterozygosity restitution within a linkage group and theoretical functions under either partial or no chiasmata interference hypotheses was successfully applied to linkage group II. The maximum value of heterozygosity restitution and the pattern of restitution along this linkage group would suggest there is partial chiasma interference. The implications of such a restitution mechanism for citrus breeding are discussed.

  17. High Affinity Binding of Chp1 Chromodomain to K9 Methylated Histone H3 is Required to Establish Centromeric Hterochromatin

    Energy Technology Data Exchange (ETDEWEB)

    Schalch, T.; Job, G; Noffsinger, V; Shanker, S; Kuscu, C; Joshua-Tor, L; Partridge, J

    2009-01-01

    In fission yeast, assembly of centromeric heterochromatin requires the RITS complex, which consists of Ago1, Tas3, Chp1, and siRNAs derived from centromeric repeats. Recruitment of RITS to centromeres has been proposed to depend on siRNA-dependent targeting of Ago1 to centromeric sequences. Previously, we demonstrated that methylated lysine 9 of histone H3 (H3K9me) acts upstream of siRNAs during heterochromatin establishment. Our crystal structure of Chp1's chromodomain in complex with a trimethylated lysine 9 H3 peptide reveals extensive sites of contact that contribute to Chp1's high-affinity binding. We found that this high-affinity binding is critical for the efficient establishment of centromeric heterochromatin, but preassembled heterochromatin can be maintained when Chp1's affinity for H3K9me is greatly reduced.

  18. Coat colour in dogs: identification of the Merle locus in the Australian shepherd breed

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    Denis Bernard

    2006-02-01

    Full Text Available Abstract Background Coat colours in canines have many natural phenotypic variants. Some of the genes and alleles involved also cause genetic developmental defects, which are also observed in humans and mice. We studied the genetic bases of the merle phenotype in dogs to shed light on the pigmentation mechanisms and to identify genes involved in these complex pathways. The merle phenotype includes a lack of eumelanic pigmentation and developmental defects, hearing impairments and microphthalmia. It is similar to that observed in microphthalmia mouse mutants. Results Taking advantage of the dog as a powerful genetic model and using recently available genomic resources, we investigated the segregation of the merle phenotype in a five-generation pedigree, comprising 96 sampled Australian shepherd dogs. Genetic linkage analysis allowed us to identify a locus for the merle phenotype, spanning 5.5 megabases, at the centromeric tip of canine chromosome 10 (CFA10. This locus was supported by a Lod score of 15.65 at a recombination fraction θ = 0. Linkage analysis in three other breeds revealed that the same region is linked to the merle phenotype. This region, which is orthologous to human chromosome 12 (HSA12 q13-q14, belongs to a conserved ordered segment in the human and mouse genome and comprises several genes potentially involved in pigmentation and development. Conclusion This study has identified the locus for the merle coat colour in dogs to be at the centromeric end of CFA10. Genetic studies on other breeds segregating the merle phenotype should allow the locus to be defined more accurately with the aim of identifying the gene. This work shows the power of the canine system to search for the genetic bases of mammalian pigmentation and developmental pathways.

  19. A Taz1- and Microtubule-Dependent Regulatory Relationship between Telomere and Centromere Positions in Bouquet Formation Secures Proper Meiotic Divisions.

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    Kazuhiro Katsumata

    2016-09-01

    Full Text Available During meiotic prophase, telomeres cluster, forming the bouquet chromosome arrangement, and facilitate homologous chromosome pairing. In fission yeast, bouquet formation requires switching of telomere and centromere positions. Centromeres are located at the spindle pole body (SPB during mitotic interphase, and upon entering meiosis, telomeres cluster at the SPB, followed by centromere detachment from the SPB. Telomere clustering depends on the formation of the microtubule-organizing center at telomeres by the linker of nucleoskeleton and cytoskeleton complex (LINC, while centromere detachment depends on disassembly of kinetochores, which induces meiotic centromere formation. However, how the switching of telomere and centromere positions occurs during bouquet formation is not fully understood. Here, we show that, when impaired telomere interaction with the LINC or microtubule disruption inhibited telomere clustering, kinetochore disassembly-dependent centromere detachment and accompanying meiotic centromere formation were also inhibited. Efficient centromere detachment required telomere clustering-dependent SPB recruitment of a conserved telomere component, Taz1, and microtubules. Furthermore, when artificial SPB recruitment of Taz1 induced centromere detachment in telomere clustering-defective cells, spindle formation was impaired. Thus, detachment of centromeres from the SPB without telomere clustering causes spindle impairment. These findings establish novel regulatory mechanisms, which prevent concurrent detachment of telomeres and centromeres from the SPB during bouquet formation and secure proper meiotic divisions.

  20. Centromeres cluster de novo at the beginning of meiosis in Brachypodium distachyon.

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    Ruoyu Wen

    Full Text Available In most eukaryotes that have been studied, the telomeres cluster into a bouquet early in meiosis, and in wheat and its relatives and in Arabidopsis the centromeres pair at the same time. In Arabidopsis, the telomeres do not cluster as a typical telomere bouquet on the nuclear membrane but are associated with the nucleolus both somatically and at the onset of meiosis. We therefore assessed whether Brachypodium distachyon, a monocot species related to cereals and whose genome is approximately twice the size of Arabidopsis thaliana, also exhibited an atypical telomere bouquet and centromere pairing. In order to investigate the occurrence of a bouquet and centromere pairing in B distachyon, we first had to establish protocols for studying meiosis in this species. This enabled us to visualize chromosome behaviour in meiocytes derived from young B distachyon spikelets in three-dimensions by fluorescent in situ hybridization (FISH, and accurately to stage meiosis based on chromatin morphology in relation to spikelet size and the timing of sample collection. Surprisingly, this study revealed that the centromeres clustered as a single site at the same time as the telomeres also formed a bouquet or single cluster.

  1. An RNA polymerase III-dependent heterochromatin barrier at fission yeast centromere 1.

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    Kristin C Scott

    Full Text Available Heterochromatin formation involves the nucleation and spreading of structural and epigenetic features along the chromatin fiber. Chromatin barriers and associated proteins counteract the spreading of heterochromatin, thereby restricting it to specific regions of the genome. We have performed gene expression studies and chromatin immunoprecipitation on strains in which native centromere sequences have been mutated to study the mechanism by which a tRNA(Alanine gene barrier (cen1 tDNA(Ala blocks the spread of pericentromeric heterochromatin at the centromere of chromosome 1 (cen1 in the fission yeast, Schizosaccharomyces pombe. Within the centromere, barrier activity is a general property of tDNAs and, unlike previously characterized barriers, requires the association of both transcription factor IIIC and RNA Polymerase III. Although the cen1 tDNA(Ala gene is actively transcribed, barrier activity is independent of transcriptional orientation. These findings provide experimental evidence for the involvement of a fully assembled RNA polymerase III transcription complex in defining independent structural and functional domains at a eukaryotic centromere.

  2. Alphoid satellite DNA is tightly associated with centromere antigens in human chromosomes throughout the cell cycle

    Energy Technology Data Exchange (ETDEWEB)

    Masumoto, Hiroshi; Sugimoto, Kenji; Okazaki, Tuneko (Nagoya Univ. (Japan))

    1989-03-01

    In this study, the authors have examined a DNA element specific to the centromere domain of human chromosomes. Purified HeLa chromosomes were digested with the restriction enzyme Sau3AI and fractionated by sedimentation through a sucrose gradient. Fractions showing antigenicity to anticentromere (kinetochore) serum obtained from a scleroderma CREST patient were used to construct a DNA library. From this library they found one clone which has specifically hybridized to the centromere domain of metaphase chromosomes using a biotinylated probe DNA and FITC-conjugated avidin. The clone contained a stretch of alphoid DNA dimer. To determine precisely the relative location of the alphoid DNA stretch and the centromere antigen, a method was developed to carry out in situ hybridization of DNA and indirect immunofluorescent staining of antigen on the same cell preparation. Using this method, they have found perfect overlapping of the alphoid DNA sites with the centromere antigen in both metaphase chromosomes and nuclei at various stages in the cell cycle. They have also observed this exact correlation at the attachment sites of artificially extended sister chromatids. These results suggest the possibility that alphoid DNA repeats are a key component of kinetochore structure.

  3. Correlation between centromere protein-F autoantibodies and cancer analyzed by enzyme-linked immunosorbent assay

    DEFF Research Database (Denmark)

    Welner, Simon; Trier, Nicole Hartwig; Morten Frisch, Morten

    2013-01-01

    Centromere protein-F (CENP-F) is a large nuclear protein of 367 kDa, which is involved in multiple mitosis-related events such as proper assembly of the kinetochores, stabilization of heterochromatin, chromosome alignment and mitotic checkpoint signaling. Several studies have shown a correlation...

  4. Chromatin determinants of the inner-centromere rely on replication factors with functions that impart cohesion

    Science.gov (United States)

    Abe, Takuya; Kawasumi, Ryotaro; Arakawa, Hiroshi; Hori, Tetsuya; Shirahige, Katsuhiko; Losada, Ana; Fukagawa, Tatsuo; Branzei, Dana

    2016-01-01

    Replication fork-associated factors promote genome integrity and protect against cancer. Mutations in the DDX11 helicase and the ESCO2 acetyltransferase also cause related developmental disorders classified as cohesinopathies. Here we generated vertebrate model cell lines of these disorders and cohesinopathies-related genes. We found that vertebrate DDX11 and Tim-Tipin are individually needed to compensate for ESCO2 loss in chromosome segregation, with DDX11 also playing complementary roles with ESCO2 in centromeric cohesion. Our study reveals that overt centromeric cohesion loss does not necessarily precede chromosome missegregation, while both these problems correlate with, and possibly originate from, inner-centromere defects involving reduced phosphorylation of histone H3T3 (pH3T3) in the region. Interestingly, the mitotic pH3T3 mark was defective in all analyzed replication-related mutants with functions in cohesion. The results pinpoint mitotic pH3T3 as a postreplicative chromatin mark that is sensitive to replication stress and conducts with different kinetics to robust centromeric cohesion and correct chromosome segregation. PMID:27636994

  5. Genetic and physical mapping of two centromere-proximal regions of chromosome IV in Aspergillus nidulans

    DEFF Research Database (Denmark)

    Aleksenko, Alexei Y.; Nielsen, Michael Lynge; Clutterbuck, A.J.

    2001-01-01

    revision of the genetic map of the chromosome, including the position of the centromere, Comparison of physical and genetic maps indicates that meiotic recombination is low in subcentromeric DNA, its frequency being reduced from 1 crossover per 0.8 Mb to approximately 1 crossover per 5 Mb per meiosis...

  6. Novel Centromeric Loci of the Wine and Beer Yeast Dekkera bruxellensis CEN1 and CEN2

    DEFF Research Database (Denmark)

    Ishchuk, Olena P.; Vojvoda Zeljko, Tanja; Schifferdecker, Anna J.

    2016-01-01

    The wine and beer yeast Dekkera bruxellensis thrives in environments that are harsh and limiting, especially in concentrations with low oxygen and high ethanol. Its different strains' chromosomes greatly vary in number (karyotype). This study isolates two novel centromeric loci (CEN1 and CEN2...

  7. Repetitive sequence analysis and karyotyping reveals centromere-associated DNA sequences in radish (Raphanus sativus L.).

    Science.gov (United States)

    He, Qunyan; Cai, Zexi; Hu, Tianhua; Liu, Huijun; Bao, Chonglai; Mao, Weihai; Jin, Weiwei

    2015-04-18

    Radish (Raphanus sativus L., 2n = 2x = 18) is a major root vegetable crop especially in eastern Asia. Radish root contains various nutritions which play an important role in strengthening immunity. Repetitive elements are primary components of the genomic sequence and the most important factors in genome size variations in higher eukaryotes. To date, studies about repetitive elements of radish are still limited. To better understand genome structure of radish, we undertook a study to evaluate the proportion of repetitive elements and their distribution in radish. We conducted genome-wide characterization of repetitive elements in radish with low coverage genome sequencing followed by similarity-based cluster analysis. Results showed that about 31% of the genome was composed of repetitive sequences. Satellite repeats were the most dominating elements of the genome. The distribution pattern of three satellite repeat sequences (CL1, CL25, and CL43) on radish chromosomes was characterized using fluorescence in situ hybridization (FISH). CL1 was predominantly located at the centromeric region of all chromosomes, CL25 located at the subtelomeric region, and CL43 was a telomeric satellite. FISH signals of two satellite repeats, CL1 and CL25, together with 5S rDNA and 45S rDNA, provide useful cytogenetic markers to identify each individual somatic metaphase chromosome. The centromere-specific histone H3 (CENH3) has been used as a marker to identify centromere DNA sequences. One putative CENH3 (RsCENH3) was characterized and cloned from radish. Its deduced amino acid sequence shares high similarities to those of the CENH3s in Brassica species. An antibody against B. rapa CENH3, specifically stained radish centromeres. Immunostaining and chromatin immunoprecipitation (ChIP) tests with anti-BrCENH3 antibody demonstrated that both the centromere-specific retrotransposon (CR-Radish) and satellite repeat (CL1) are directly associated with RsCENH3 in radish. Proportions

  8. Sisters unbound is required for meiotic centromeric cohesion in Drosophila melanogaster.

    Science.gov (United States)

    Krishnan, Badri; Thomas, Sharon E; Yan, Rihui; Yamada, Hirotsugu; Zhulin, Igor B; McKee, Bruce D

    2014-11-01

    Regular meiotic chromosome segregation requires sister centromeres to mono-orient (orient to the same pole) during the first meiotic division (meiosis I) when homologous chromosomes segregate, and to bi-orient (orient to opposite poles) during the second meiotic division (meiosis II) when sister chromatids segregate. Both orientation patterns require cohesion between sister centromeres, which is established during meiotic DNA replication and persists until anaphase of meiosis II. Meiotic cohesion is mediated by a conserved four-protein complex called cohesin that includes two structural maintenance of chromosomes (SMC) subunits (SMC1 and SMC3) and two non-SMC subunits. In Drosophila melanogaster, however, the meiotic cohesion apparatus has not been fully characterized and the non-SMC subunits have not been identified. We have identified a novel Drosophila gene called sisters unbound (sunn), which is required for stable sister chromatid cohesion throughout meiosis. sunn mutations disrupt centromere cohesion during prophase I and cause high frequencies of non-disjunction (NDJ) at both meiotic divisions in both sexes. SUNN co-localizes at centromeres with the cohesion proteins SMC1 and SOLO in both sexes and is necessary for the recruitment of both proteins to centromeres. Although SUNN lacks sequence homology to cohesins, bioinformatic analysis indicates that SUNN may be a structural homolog of the non-SMC cohesin subunit stromalin (SA), suggesting that SUNN may serve as a meiosis-specific cohesin subunit. In conclusion, our data show that SUNN is an essential meiosis-specific Drosophila cohesion protein. Copyright © 2014 by the Genetics Society of America.

  9. Esperanto for histones: CENP-A, not CenH3, is the centromeric histone H3 variant.

    Science.gov (United States)

    Earnshaw, W C; Allshire, R C; Black, B E; Bloom, K; Brinkley, B R; Brown, W; Cheeseman, I M; Choo, K H A; Copenhaver, G P; Deluca, J G; Desai, A; Diekmann, S; Erhardt, S; Fitzgerald-Hayes, M; Foltz, D; Fukagawa, T; Gassmann, R; Gerlich, D W; Glover, D M; Gorbsky, G J; Harrison, S C; Heun, P; Hirota, T; Jansen, L E T; Karpen, G; Kops, G J P L; Lampson, M A; Lens, S M; Losada, A; Luger, K; Maiato, H; Maddox, P S; Margolis, R L; Masumoto, H; McAinsh, A D; Mellone, B G; Meraldi, P; Musacchio, A; Oegema, K; O'Neill, R J; Salmon, E D; Scott, K C; Straight, A F; Stukenberg, P T; Sullivan, B A; Sullivan, K F; Sunkel, C E; Swedlow, J R; Walczak, C E; Warburton, P E; Westermann, S; Willard, H F; Wordeman, L; Yanagida, M; Yen, T J; Yoda, K; Cleveland, D W

    2013-04-01

    The first centromeric protein identified in any species was CENP-A, a divergent member of the histone H3 family that was recognised by autoantibodies from patients with scleroderma-spectrum disease. It has recently been suggested to rename this protein CenH3. Here, we argue that the original name should be maintained both because it is the basis of a long established nomenclature for centromere proteins and because it avoids confusion due to the presence of canonical histone H3 at centromeres.

  10. Centromere repositioning in the X chromosome of XO/XO mammals, Ryukyu spiny rat.

    Science.gov (United States)

    Kobayashi, Tsuyoshi; Yamada, Fumio; Hashimoto, Takuma; Abe, Shintaro; Matsuda, Yoichi; Kuroiwa, Asato

    2008-01-01

    Two species of Ryukyu spiny rat, Tokudaia osimensis and Tokudaia tokunoshimensis, have an XO/XO sex chromosome constitution with no cytogenetically visible Y chromosome in both sexes. The single X chromosomes of T. osimensis and T. tokunoshimensis are submetacentric and subtelocentric, respectively. It was therefore suggested that a pericentric inversion event occurred in the X chromosome of either species. To identify X chromosome rearrangements that have occurred between the two species, we mapped 22 mouse cDNA clones of the X-linked genes on the chromosomes of the two species by direct R-banding FISH. The gene orders of the X chromosomes were conserved in the two species, whereas the position of the centromere on the X chromosome was different. This result indicates that the rearrangement which occurred in either of the X chromosomes after the two species diverged from a common ancestor involved not pericentric inversion but centromere repositioning.

  11. Centromere repositioning explains fundamental number variability in the New World monkey genus Saimiri.

    Science.gov (United States)

    Chiatante, Giorgia; Capozzi, Oronzo; Svartman, Marta; Perelman, Polina; Centrone, Lucy; Romanenko, Svetlana S; Ishida, Takafumi; Valeri, Mirela; Roelke-Parker, Melody E; Stanyon, Roscoe

    2017-08-01

    Cytogenetics has historically played a key role in research on squirrel monkey (genus Saimiri) evolutionary biology. Squirrel monkeys have a diploid number of 2n = 44, but vary in fundamental number (FN). Apparently, differences in FN have phylogenetic implications and are correlated with geographic regions. A number of hypothetical mechanisms were proposed to explain difference in FN: translocations, heterochromatin, or, most commonly, pericentric inversions. Recently, an additional mechanism, centromere repositioning, was discovered, which can alter chromosome morphology and FN. Here, we used chromosome banding, chromosome painting, and BAC-FISH to test these hypotheses. We demonstrate that centromere repositioning on chromosomes 5 and 15 is the mechanism that accounts for differences in FN. Current phylogenomic trees of platyrrhines provide a temporal framework for evolutionary new centromeres (ENC) in Saimiri. The X-chromosome ENC could be up to 15 million years (my) old that on chromosome 5 as recent as 0.3 my. The chromosome 15 ENC is intermediate, as young as 2.24 my. All ENC have abundant satellite DNAs indicating that the maturation process was fairly rapid. Callithrix jacchus was used as an outgroup for the BAC-FISH data analysis. Comparison with scaffolds from the S. boliviensis genome revealed an error in the last marmoset genome release. Future research including at the sequence level will provide better understanding of chromosome evolution in Saimiri and other platyrrhines. Probably other cases of differences in chromosome morphology and FN, both within and between taxa, will be shown to be due to centromere repositioning and not pericentric inversions.

  12. Identification of a centromeric exchange of acrocentric chromosomes by fluorescence in situ hybridization

    Energy Technology Data Exchange (ETDEWEB)

    Yu, C.W.; Immken, L.; Curry, C.J.R. [UCSF, Fresno, CA (United States)] [and others

    1994-09-01

    Exchanges of the peri-centromeric area of acrocentric chromosomes are difficult to identify using the conventional cytogenetic techniques. Fluorescence in situ hybridization (FISH) provides a new way for precisely identifying such rearrangements. Here we report a case of centromeric rearrangement in an amniotic fluid specimen with an extra marker chromosome. M.G., a 41-year-old G1, was referred for advanced maternal age. Chromosome studies revealed a 47,XX +mar karyotype. The marker appeared to be bi-satallited with a single C band. Chromosome studies from the parents were normal. The parents elected to terminate the pregnancy. Anatomical examination of the abortus revealed a very short neck, posteriorly rotated ears, high set cecum, absent hepatic lobation and low abdominal kidneys with short ureters. FISH studies with alpha-satellite probes of 13/21, 14/22, and 15, and the DiGeorge probe, indicated that there is a translocation of 21 alpha-satellite to the 22, and that the marker chromosome probably consists of 14/22 alpha-satellite material. FISH analysis of the parents chromosome revealed that father had the translocation of 21 alpha-satellite to the 22 as well. Exchanges of centromeric material among the acrocentric chromosomes may not be an uncommon event in humans. Although it probably has no clinical significance, it may result in non-disjunction or marker chromosome formation from an uncommon satellite association. With the use of FISH techniques, exchanges involving the centromeric regions of acrocentric chromosomes can be identified.

  13. The Smc5-Smc6 complex regulates recombination at centromeric regions and affects kinetochore protein sumoylation during normal growth.

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    Vladimir Yong-Gonzales

    Full Text Available The Smc5-Smc6 complex in Saccharomyces cerevisiae is both essential for growth and important for coping with genotoxic stress. While it facilitates damage tolerance throughout the genome under genotoxin treatment, its function during unperturbed growth is mainly documented for repetitive DNA sequence maintenance. Here we provide physical and genetic evidence showing that the Smc5-Smc6 complex regulates recombination at non-repetitive loci such as centromeres in the absence of DNA damaging agents. Mutating Smc6 results in the accumulation of recombination intermediates at centromeres and other unique sequences as assayed by 2D gel analysis. In addition, smc6 mutant cells exhibit increased levels of Rad52 foci that co-localize with centromere markers. A rad52 mutation that decreases centromeric, but not overall, levels of Rad52 foci in smc6 mutants suppresses the nocodazole sensitivity of these cells, suggesting that the Smc6-mediated regulation of recombination at centromeric regions impacts centromere-related functions. In addition to influencing recombination, the SUMO ligase subunit of the Smc5-Smc6 complex promotes the sumoylation of two kinetochore proteins and affects mitotic spindles. These results suggest that the Smc5-Smc6 complex regulates both recombination and kinetochore sumoylation to facilitate chromosomal maintenance during growth.

  14. SUMOylated ORC2 Recruits a Histone Demethylase to Regulate Centromeric Histone Modification and Genomic Stability

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    Chao Huang

    2016-04-01

    Full Text Available Origin recognition complex 2 (ORC2, a subunit of the ORC, is essential for DNA replication initiation in eukaryotic cells. In addition to a role in DNA replication initiation at the G1/S phase, ORC2 has been shown to localize to the centromere during the G2/M phase. Here, we show that ORC2 is modified by small ubiquitin-like modifier 2 (SUMO2, but not SUMO1, at the G2/M phase of the cell cycle. SUMO2-modification of ORC2 is important for the recruitment of KDM5A in order to convert H3K4me3 to H3K4me2, a “permissive” histone marker for α-satellite transcription at the centromere. Persistent expression of SUMO-less ORC2 led to reduced α-satellite transcription and impaired pericentric heterochromatin silencing, which resulted in re-replication of heterochromatin DNA. DNA re-replication eventually activated the DNA damage response, causing the bypass of mitosis and the formation of polyploid cells. Thus, ORC2 sustains genomic stability by recruiting KDM5A to maintain centromere histone methylation in order to prevent DNA re-replication.

  15. The Association of LINE-1 Hypomethylation with Age and Centromere Positive Micronuclei in Human Lymphocytes.

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    Yoon Hee Cho

    Full Text Available Global hypomethylation in white blood cell (WBC DNA has recently been proposed as a potential biomarker for determining cancer risk through genomic instability. However, the amplitude of the changes associated with age and the impacts of environmental factors on DNA methylation are unclear. In this study, we investigated the association of genomic hypomethylation with age, cigarette use, drinking status and the presence of centromere positive micronuclei (MNC+-a biomarker for age-dependent genomic instability. Genomic hypomethylation of the repetitive element LINE-1 was measured in WBC DNA from 32 healthy male volunteers using the pyrosequencing assay. We also measured MNC+ with the micronucleus-centromere assay using a pan-centromeric probe. Possibly due to the small sample size and resulting low statistical power, smoking and drinking status had no significant effect on LINE-1 hypomethylation or the occurrence of MNC+. Consequently, we did not include them in further analyses. In contrast, LINE-1 hypomethylation and age significantly predicted MNC+; therefore, we examined whether LINE-1 hypomethylation plays a role in MNC+ formation by age, since genomic hypomethylation is associated with genomic instability. However, LINE-1 hypomethylation did not significantly mediate the effect of age on MNC+. Our data indicate that the repetitive element LINE-1 is demethylated with age and increasing MNC+ frequency, but additional studies are needed to fully understand the relation between genomic DNA hypomethylation, age and genomic instability.

  16. Evolutionary Origin of Higher-Order Repeat Structure in Alpha-Satellite DNA of Primate Centromeres

    Science.gov (United States)

    Koga, Akihiko; Hirai, Yuriko; Terada, Shoko; Jahan, Israt; Baicharoen, Sudarath; Arsaithamkul, Visit; Hirai, Hirohisa

    2014-01-01

    Alpha-satellite DNA (AS) is a main DNA component of primate centromeres, consisting of tandemly repeated units of ∼170 bp. The AS of humans contains sequences organized into higher-order repeat (HOR) structures, in which a block of multiple repeat units forms a larger repeat unit and the larger units are repeated tandemly. The presence of HOR in AS is widely thought to be unique to hominids (family Hominidae; humans and great apes). Recently, we have identified an HOR-containing AS in the siamang, which is a small ape species belonging to the genus Symphalangus in the family Hylobatidae. This result supports the view that HOR in AS is an attribute of hominoids (superfamily Hominoidea) rather than hominids. A single example is, however, not sufficient for discussion of the evolutionary origin of HOR-containing AS. In the present study, we developed an efficient method for detecting signs of large-scale HOR and demonstrated HOR of AS in all the three other genera. Thus, AS organized into HOR occurs widely in hominoids. Our results indicate that (i) HOR-containing AS was present in the last common ancestor of hominoids or (ii) HOR-containing AS emerged independently in most or all basal branches of hominoids. We have also confirmed HOR occurrence in centromeric AS in the Hylobatidae family, which remained unclear in our previous study because of the existence of AS in subtelomeric regions, in addition to centromeres, of siamang chromosomes. PMID:24585002

  17. Centromere binding and a conserved role in chromosome stability for SUMO-dependent ubiquitin ligases.

    Directory of Open Access Journals (Sweden)

    Loes A L van de Pasch

    Full Text Available The Saccharomyces cerevisiae Slx5/8 complex is the founding member of a recently defined class of SUMO-targeted ubiquitin ligases (STUbLs. Slx5/8 has been implicated in genome stability and transcription, but the precise contribution is unclear. To characterise Slx5/8 function, we determined genome-wide changes in gene expression upon loss of either subunit. The majority of mRNA changes are part of a general stress response, also exhibited by mutants of other genome integrity pathways and therefore indicative of an indirect effect on transcription. Genome-wide binding analysis reveals a uniquely centromeric location for Slx5. Detailed phenotype analyses of slx5Δ and slx8Δ mutants show severe mitotic defects that include aneuploidy, spindle mispositioning, fish hooks and aberrant spindle kinetics. This is associated with accumulation of the PP2A regulatory subunit Rts1 at centromeres prior to entry into anaphase. Knockdown of the human STUbL orthologue RNF4 also results in chromosome segregation errors due to chromosome bridges. The study shows that STUbLs have a conserved role in maintenance of chromosome stability and links SUMO-dependent ubiquitination to a centromere-specific function during mitosis.

  18. Centromere binding and a conserved role in chromosome stability for SUMO-dependent ubiquitin ligases.

    Science.gov (United States)

    van de Pasch, Loes A L; Miles, Antony J; Nijenhuis, Wilco; Brabers, Nathalie A C H; van Leenen, Dik; Lijnzaad, Philip; Brown, Markus K; Ouellet, Jimmy; Barral, Yves; Kops, Geert J P L; Holstege, Frank C P

    2013-01-01

    The Saccharomyces cerevisiae Slx5/8 complex is the founding member of a recently defined class of SUMO-targeted ubiquitin ligases (STUbLs). Slx5/8 has been implicated in genome stability and transcription, but the precise contribution is unclear. To characterise Slx5/8 function, we determined genome-wide changes in gene expression upon loss of either subunit. The majority of mRNA changes are part of a general stress response, also exhibited by mutants of other genome integrity pathways and therefore indicative of an indirect effect on transcription. Genome-wide binding analysis reveals a uniquely centromeric location for Slx5. Detailed phenotype analyses of slx5Δ and slx8Δ mutants show severe mitotic defects that include aneuploidy, spindle mispositioning, fish hooks and aberrant spindle kinetics. This is associated with accumulation of the PP2A regulatory subunit Rts1 at centromeres prior to entry into anaphase. Knockdown of the human STUbL orthologue RNF4 also results in chromosome segregation errors due to chromosome bridges. The study shows that STUbLs have a conserved role in maintenance of chromosome stability and links SUMO-dependent ubiquitination to a centromere-specific function during mitosis.

  19. A stable acentric marker chromosome: Possible existence of an intercalary ancient centromere at distal 8p

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, Hirofumi; Fukushima, Yoshimitsu; Wakui, Keiko; Ogawa, Kioyshi [Saitama Children`s Medical Center, Iwatsuki (Japan); Okano, Tetsuroh [Kitazato Univ., Tokyo (Japan); Niikawa, Norio [Nagasaki Univ. School of Medicine (Japan)

    1994-12-01

    A centromere is considered to be an essential chromosomal component where microtubule-kinetochore interaction occurs to segregate sister chromatids faithfully and acentric chromosomes are unstable and lost through cell divisions. We report a novel marker chromosome that was acentric but stable through cell divisions. The patient was a 2-year-old girl with mental retardation, patent ductus arteriosus, and mild dysmorphic features. G-banded chromosome analysis revealed that an additional small marker chromosome was observed in all 100 cells examined. By the reverse-chromosome-painting method, the marker was found to originate from the distal region of 8p, and a subsequent two-color FISH analysis with cosmid probes around the region revealed that the marker was an inverted duplication interpreted as 8pter {yields} p23.1::p23.1 {yields} 8pter. No centromeric region was involved in the marker. By FISH, no {alpha}-satellite sequence was detected on the marker, while a telomere sequence was detected at each end. Anti-kinetochore immunostaining, using a serum from a patient with CREST (calcinosis, Raynaud syndrome, esophageal dismotility, sclerodactyly, and telangiectasia) syndrome, showed a pair of signals on the marker, which indicated that a functional kinetochore was present on the marker. The analysis of this patient might suggest the possibility that an ancient centromere sequence exists at distal 8p (8p23.1-pter) and was activated through the chromosome rearrangement in the patient.

  20. Perturbation of Incenp function impedes anaphase chromatid movements and chromosomal passenger protein flux at centromeres.

    Science.gov (United States)

    Ahonen, Leena J; Kukkonen, Anu M; Pouwels, Jeroen; Bolton, Margaret A; Jingle, Christopher D; Stukenberg, P Todd; Kallio, Marko J

    2009-02-01

    Incenp is an essential mitotic protein that, together with Aurora B, Survivin, and Borealin, forms the core of the chromosomal passenger protein complex (CPC). The CPC regulates various mitotic processes and functions to maintain genomic stability. The proper subcellular localization of the CPC and its full catalytic activity require the presence of each core subunit in the complex. We have investigated the mitotic tasks of the CPC using a function blocking antibody against Incenp microinjected into cells at different mitotic phases. This method allowed temporal analysis of CPC functions without perturbation of complex assembly or activity prior to injection. We have also studied the dynamic properties of Incenp and Aurora B using fusion protein photobleaching. We found that in early mitotic cells, Incenp and Aurora B exhibit dynamic turnover at centromeres, which is prevented by the anti-Incenp antibody. In these cells, the loss of centromeric CPC turnover is accompanied by forced mitotic exit without the execution of cytokinesis. Introduction of anti-Incenp antibody into early anaphase cells causes abnormalities in sister chromatid separation through defects in anaphase spindle functions. In summary, our data uncovers new mitotic roles for the CPC in anaphase and proposes that CPC turnover at centromeres modulates spindle assembly checkpoint signaling.

  1. Locus of control and competence.

    Science.gov (United States)

    Naditch, M P; DeMaio, T

    1975-12-01

    The relation of locus of control and competence in school achievement, social interactions, sports, and home related activities was examined. The sample consisted of 346 ninth-grade students, and competence was measured using self-report, antional battery test scores, grades, and sociometric ratings. Among males, locus of control was significantly related to competent performance only among those subjects who placed a high value on outcomes in each area. Among females, the pattern was exactly reversed. Locus of control and various forms of competence were related only in areas of low interest value. The implications of these findings were discussed.

  2. Genomic analysis of the Xp21 region around the RP3 locus

    Energy Technology Data Exchange (ETDEWEB)

    Navia, B.A. [Massachusetts General Hospital, Boston, MA (United States); Eisenman, R.E.; Bruns, G.A. [Children`s Hospital, Boston, MA (United States)] [and others

    1994-09-01

    One form of X-linked retinitis pigmentosa has been localized by deletion and linkage analysis to proximal Xp21 near the OTC locus and the proximal breakpoint of the BB deletion. A deletion junction clone, previously isolated from this region, was used to initiate a series of bidirectional walks in a human genomic library in EMBL3A. A phage contig of nearly 70 kb has been cloned and systematically searched for conserved sequences and CA repeats. A number of unique sequences around the breakpoint have been sequenced and analyzed with exon identification programs. An HTF island was identified approximately 35 kb distal to the centromeric breakpoint of the BB deletion and several CA repeat-containing areas were found in the contig. Two YACs that contain the breakpoint and surrounding region were isolated. A phage sublibrary was constructed from one of the YACs and is being used to extend the contig map further centromeric. To isolate transcripts from the region, two rounds of cDNA selection from a combined short insert human retinal and fetal brain library were performed against the pooled phage clones from the contig and against the pooled phage from the YAC derived sublibrary. Among the selected cDNAs, several unique sequences have been identified and are currently being mapped and sequenced.

  3. Separase Is Required for Homolog and Sister Disjunction during Drosophila melanogaster Male Meiosis, but Not for Biorientation of Sister Centromeres.

    Science.gov (United States)

    Blattner, Ariane C; Chaurasia, Soumya; McKee, Bruce D; Lehner, Christian F

    2016-04-01

    Spatially controlled release of sister chromatid cohesion during progression through the meiotic divisions is of paramount importance for error-free chromosome segregation during meiosis. Cohesion is mediated by the cohesin protein complex and cleavage of one of its subunits by the endoprotease separase removes cohesin first from chromosome arms during exit from meiosis I and later from the pericentromeric region during exit from meiosis II. At the onset of the meiotic divisions, cohesin has also been proposed to be present within the centromeric region for the unification of sister centromeres into a single functional entity, allowing bipolar orientation of paired homologs within the meiosis I spindle. Separase-mediated removal of centromeric cohesin during exit from meiosis I might explain sister centromere individualization which is essential for subsequent biorientation of sister centromeres during meiosis II. To characterize a potential involvement of separase in sister centromere individualization before meiosis II, we have studied meiosis in Drosophila melanogaster males where homologs are not paired in the canonical manner. Meiosis does not include meiotic recombination and synaptonemal complex formation in these males. Instead, an alternative homolog conjunction system keeps homologous chromosomes in pairs. Using independent strategies for spermatocyte-specific depletion of separase complex subunits in combination with time-lapse imaging, we demonstrate that separase is required for the inactivation of this alternative conjunction at anaphase I onset. Mutations that abolish alternative homolog conjunction therefore result in random segregation of univalents during meiosis I also after separase depletion. Interestingly, these univalents become bioriented during meiosis II, suggesting that sister centromere individualization before meiosis II does not require separase.

  4. Locus-Specific DNA Methylation Reprogramming During Early Porcine Embryogenesis1

    Science.gov (United States)

    Zhao, Ming-Tao; Rivera, Rocio M.; Prather, Randall S.

    2013-01-01

    ABSTRACT During early mammalian embryogenesis, there is a wave of DNA demethylation postfertilization and de novo methylation around implantation. The paternal genome undergoes active DNA demethylation, whereas the maternal genome is passively demethylated after fertilization in most mammals except for sheep and rabbits. However, the emerging genome-wide DNA methylation landscape has revealed a regulatory and locus-specific DNA methylation reprogramming pattern in mammalian preimplantation embryos. Here we optimized a bisulfite sequencing protocol to draw base-resolution DNA methylation profiles of several selected genes in gametes, early embryos, and somatic tissue. We observed locus-specific DNA methylation reprogramming in early porcine embryos. First, some pluripotency genes (POU5F1 and NANOG) followed a typical wave of DNA demethylation and remethylation, whereas CpG-rich regions of SOX2 and CDX2 loci were hypomethylated throughout development. Second, a differentially methylated region of an imprint control region in the IGF2/H19 locus exhibited differential DNA methylation which was maintained in porcine early embryos. Third, a centromeric repeat element retained a moderate DNA methylation level in gametes, early embryos, and somatic tissue. The diverse DNA methylation reprogramming during early embryogenesis is thought to be possibly associated with the multiple functions of DNA methylation in transcriptional regulation, genome stability and genomic imprinting. The latest technology such as oxidative bisulfite sequencing to identify 5-hydroxymethylcytosine will further clarify the DNA methylation reprogramming during porcine embryonic development. PMID:23303676

  5. Replication of alpha-satellite DNA arrays in endogenous human centromeric regions and in human artificial chromosome.

    Science.gov (United States)

    Erliandri, Indri; Fu, Haiqing; Nakano, Megumi; Kim, Jung-Hyun; Miga, Karen H; Liskovykh, Mikhail; Earnshaw, William C; Masumoto, Hiroshi; Kouprina, Natalay; Aladjem, Mirit I; Larionov, Vladimir

    2014-10-01

    In human chromosomes, centromeric regions comprise megabase-size arrays of 171 bp alpha-satellite DNA monomers. The large distances spanned by these arrays preclude their replication from external sites and imply that the repetitive monomers contain replication origins. However, replication within these arrays has not previously been profiled and the role of alpha-satellite DNA in initiation of DNA replication has not yet been demonstrated. Here, replication of alpha-satellite DNA in endogenous human centromeric regions and in de novo formed Human Artificial Chromosome (HAC) was analyzed. We showed that alpha-satellite monomers could function as origins of DNA replication and that replication of alphoid arrays organized into centrochromatin occurred earlier than those organized into heterochromatin. The distribution of inter-origin distances within centromeric alphoid arrays was comparable to the distribution of inter-origin distances on randomly selected non-centromeric chromosomal regions. Depletion of CENP-B, a kinetochore protein that binds directly to a 17 bp CENP-B box motif common to alpha-satellite DNA, resulted in enrichment of alpha-satellite sequences for proteins of the ORC complex, suggesting that CENP-B may have a role in regulating the replication of centromeric regions. Mapping of replication initiation sites in the HAC revealed that replication preferentially initiated in transcriptionally active regions. Published by Oxford University Press on behalf of Nucleic Acids Research 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  6. Centromere replication timing determines different forms of genomic instability in Saccharomyces cerevisiae checkpoint mutants during replication stress.

    Science.gov (United States)

    Feng, Wenyi; Bachant, Jeff; Collingwood, David; Raghuraman, M K; Brewer, Bonita J

    2009-12-01

    Yeast replication checkpoint mutants lose viability following transient exposure to hydroxyurea, a replication-impeding drug. In an effort to understand the basis for this lethality, we discovered that different events are responsible for inviability in checkpoint-deficient cells harboring mutations in the mec1 and rad53 genes. By monitoring genomewide replication dynamics of cells exposed to hydroxyurea, we show that cells with a checkpoint deficient allele of RAD53, rad53K227A, fail to duplicate centromeres. Following removal of the drug, however, rad53K227A cells recover substantial DNA replication, including replication through centromeres. Despite this recovery, the rad53K227A mutant fails to achieve biorientation of sister centromeres during recovery from hydroxyurea, leading to secondary activation of the spindle assembly checkpoint (SAC), aneuploidy, and lethal chromosome segregation errors. We demonstrate that cell lethality from this segregation defect could be partially remedied by reinforcing bipolar attachment. In contrast, cells with the mec1-1 sml1-1 mutations suffer from severely impaired replication resumption upon removal of hydroxyurea. mec1-1 sml1-1 cells can, however, duplicate at least some of their centromeres and achieve bipolar attachment, leading to abortive segregation and fragmentation of incompletely replicated chromosomes. Our results highlight the importance of replicating yeast centromeres early and reveal different mechanisms of cell death due to differences in replication fork progression.

  7. Regulation of Centromere Localization of the Drosophila Shugoshin MEI-S332 and Sister-Chromatid Cohesion in Meiosis

    Science.gov (United States)

    Nogueira, Cristina; Kashevsky, Helena; Pinto, Belinda; Clarke, Astrid; Orr-Weaver, Terry L.

    2014-01-01

    The Shugoshin (Sgo) protein family helps to ensure proper chromosome segregation by protecting cohesion at the centromere by preventing cleavage of the cohesin complex. Some Sgo proteins also influence other aspects of kinetochore-microtubule attachments. Although many Sgo members require Aurora B kinase to localize to the centromere, factors controlling delocalization are poorly understood and diverse. Moreover, it is not clear how Sgo function is inactivated and whether this is distinct from delocalization. We investigated these questions in Drosophila melanogaster, an organism with superb chromosome cytology to monitor Sgo localization and quantitative assays to test its function in sister-chromatid segregation in meiosis. Previous research showed that in mitosis in cell culture, phosphorylation of the Drosophila Sgo, MEI-S332, by Aurora B promotes centromere localization, whereas Polo phosphorylation promotes delocalization. These studies also suggested that MEI-S332 can be inactivated independently of delocalization, a conclusion supported here by localization and function studies in meiosis. Phosphoresistant and phosphomimetic mutants for the Aurora B and Polo phosphorylation sites were examined for effects on MEI-S332 localization and chromosome segregation in meiosis. Strikingly, MEI-S332 with a phosphomimetic mutation in the Aurora B phosphorylation site prematurely dissociates from the centromeres in meiosis I. Despite the absence of MEI-S332 on meiosis II centromeres in male meiosis, sister chromatids segregate normally, demonstrating that detectable levels of this Sgo are not essential for chromosome congression, kinetochore biorientation, or spindle assembly. PMID:25081981

  8. Novel Centromeric Loci of the Wine and Beer Yeast Dekkera bruxellensis CEN1 and CEN2.

    Science.gov (United States)

    Ishchuk, Olena P; Vojvoda Zeljko, Tanja; Schifferdecker, Anna J; Mebrahtu Wisén, Sofia; Hagström, Åsa K; Rozpędowska, Elżbieta; Rørdam Andersen, Mikael; Hellborg, Linda; Ling, Zhihao; Sibirny, Andrei A; Piškur, Jure

    2016-01-01

    The wine and beer yeast Dekkera bruxellensis thrives in environments that are harsh and limiting, especially in concentrations with low oxygen and high ethanol. Its different strains' chromosomes greatly vary in number (karyotype). This study isolates two novel centromeric loci (CEN1 and CEN2), which support both the yeast's autonomous replication and the stable maintenance of plasmids. In the sequenced genome of the D. bruxellensis strain CBS 2499, CEN1 and CEN2 are each present in one copy. They differ from the known "point" CEN elements, and their biological activity is retained within ~900-1300 bp DNA segments. CEN1 and CEN2 have features of both "point" and "regional" centromeres: They contain conserved DNA elements, ARSs, short repeats, one tRNA gene, and transposon-like elements within less than 1 kb. Our discovery of a miniature inverted-repeat transposable element (MITE) next to CEN2 is the first report of such transposons in yeast. The transformants carrying circular plasmids with cloned CEN1 and CEN2 undergo a phenotypic switch: They form fluffy colonies and produce three times more biofilm. The introduction of extra copies of CEN1 and CEN2 promotes both genome rearrangements and ploidy shifts, with these effects mediated by homologous recombination (between circular plasmid and genome centromere copy) or by chromosome breakage when integrated. Also, the proximity of the MITE-like transposon to CEN2 could translocate CEN2 within the genome or cause chromosomal breaks, so promoting genome dynamics. With extra copies of CEN1 and CEN2, the yeast's enhanced capacities to rearrange its genome and to change its gene expression could increase its abilities for exploiting new and demanding niches.

  9. Stem-loop structures of the repetitive DNA sequences located at human centromeres

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, G.; Garcia, A.E.; Ratliff, R.; Moyzis, R.K. [Los Alamos National Lab., NM (United States); Catasti, P.; Hong, Lin; Yau, P. [California Univ., Davis, CA (United States). Dept. of Biological Chemistry; Bradbury, E.M. [Los Alamos National Lab., NM (United States)]|[California Univ., Davis, CA (United States). Dept. of Biological Chemistry

    1993-09-01

    The presence of the highly conserved repetitive DNA sequences in the human centromeres argues for a special role of these sequences in their biological functions - most likely achieved by the formation of unusual structures. This prompted us to carry out quantitative one- and two-dimensional nuclear magnetic resonance (lD/2D NMR) spectroscopy to determine the structural properties of the human centromeric repeats, d(AATGG){sub n.d}(CCATT){sub n}. The studies on centromeric DNAs reveal that the complementary sequence, d(AATGG){sub n.d}(CCATT){sub n}, adopts the usual Watson-Crick B-DNA duplex and the pyrimidine-rich d(CCATT){sub n} strand is essentially a random coil. However, the purine-rich d(AATGG){sub n} strand is shown to adopt unusual stem-loop structures for repeat lengths, n=2,3,4, and 6. In addition to normal Watson-Crick A{center_dot}T pairs, the stem-loop structures are stabilized by mismatch A{center_dot}G and G{center_dot}G pairs in the stem and G-G-A stacking in the loop. Stem-loop structures of d(AATGG)n are independently verified by gel electrophoresis and nuclease digestion studies. Thermal melting studies show that the DNA repeats, d(AATGG){sub n}, are as stable as the corresponding Watson-Crick duplex d(AATGG){sub n.d}(CCATT){sub n}. Therefore, the sequence d(AATGG){sub n} can, indeed, nucleate a stem-loop structure at little free-energy cost and if, during mitosis, they are located on the chromosome surface they can provide specific recognition sites for kinetochore function.

  10. Novel Centromeric Loci of the Wine and Beer Yeast Dekkera bruxellensis CEN1 and CEN2.

    Directory of Open Access Journals (Sweden)

    Olena P Ishchuk

    Full Text Available The wine and beer yeast Dekkera bruxellensis thrives in environments that are harsh and limiting, especially in concentrations with low oxygen and high ethanol. Its different strains' chromosomes greatly vary in number (karyotype. This study isolates two novel centromeric loci (CEN1 and CEN2, which support both the yeast's autonomous replication and the stable maintenance of plasmids. In the sequenced genome of the D. bruxellensis strain CBS 2499, CEN1 and CEN2 are each present in one copy. They differ from the known "point" CEN elements, and their biological activity is retained within ~900-1300 bp DNA segments. CEN1 and CEN2 have features of both "point" and "regional" centromeres: They contain conserved DNA elements, ARSs, short repeats, one tRNA gene, and transposon-like elements within less than 1 kb. Our discovery of a miniature inverted-repeat transposable element (MITE next to CEN2 is the first report of such transposons in yeast. The transformants carrying circular plasmids with cloned CEN1 and CEN2 undergo a phenotypic switch: They form fluffy colonies and produce three times more biofilm. The introduction of extra copies of CEN1 and CEN2 promotes both genome rearrangements and ploidy shifts, with these effects mediated by homologous recombination (between circular plasmid and genome centromere copy or by chromosome breakage when integrated. Also, the proximity of the MITE-like transposon to CEN2 could translocate CEN2 within the genome or cause chromosomal breaks, so promoting genome dynamics. With extra copies of CEN1 and CEN2, the yeast's enhanced capacities to rearrange its genome and to change its gene expression could increase its abilities for exploiting new and demanding niches.

  11. RNA Pol II promotes transcription of centromeric satellite DNA in beetles.

    Directory of Open Access Journals (Sweden)

    Zeljka Pezer

    Full Text Available Transcripts of centromeric satellite DNAs are known to play a role in heterochromatin formation as well as in establishment of the kinetochore. However, little is known about basic mechanisms of satellite DNA expression within constitutive heterochromatin and its regulation. Here we present comprehensive analysis of transcription of abundant centromeric satellite DNA, PRAT from beetle Palorus ratzeburgii (Coleoptera. This satellite is characterized by preservation and extreme sequence conservation among evolutionarily distant insect species. PRAT is expressed in all three developmental stages: larvae, pupae and adults at similar level. Transcripts are abundant comprising 0.033% of total RNA and are heterogeneous in size ranging from 0.5 kb up to more than 5 kb. Transcription proceeds from both strands but with 10 fold different expression intensity and transcripts are not processed into siRNAs. Most of the transcripts (80% are not polyadenylated and remain in the nucleus while a small portion is exported to the cytoplasm. Multiple, irregularly distributed transcription initiation sites as well as termination sites have been mapped within the PRAT sequence using primer extension and RLM-RACE. The presence of cap structure as well as poly(A tails in a portion of the transcripts indicate RNA polymerase II-dependent transcription and a putative polymerase II promoter site overlaps the most conserved part of the PRAT sequence. The treatment of larvae with alpha-amanitin decreases the level of PRAT transcripts at concentrations that selectively inhibit pol II activity. In conclusion, stable, RNA polymerase II dependant transcripts of abundant centromeric satellite DNA, not regulated by RNAi, have been identified and characterized. This study offers a basic understanding of expression of highly abundant heterochromatic DNA which in beetle species constitutes up to 50% of the genome.

  12. Pobreza y Locus de Control

    Directory of Open Access Journals (Sweden)

    Joaquina Palomar Lever

    2004-01-01

    Full Text Available En este trabajo se busco conocer si existen diferencias en el locus de control según el nivel de pobreza en una población de 900 personas clasificadas en tres grupos: pobres extremos, pobres moderados y no pobres. Los sujetos estudiados compartieron la característica de ser personas económicamente independientes. Para este estudio se utilizaron como instrumentos de medición, un cuestionario sociodemográfico y una escala de locus de control. Los resultados muestran que los grupos de mayor ingreso familiar así como el grupo de no pobres y el de pobres moderados presentan en mayor medida un locus de control interno, mientras que el grupo de pobres extremos un mayor locus de control externo; por otro lado se observó que las personas de sexo masculino así como los de más edad (36 a 72 años presentan un locus de control más interno que aquellas personas de sexo femenino y de menor edad (19 a 35 años. Además, las personas con mayor nivel educativo (licenciatura y postgrado presentan una mayor tendencia hacia la internalidad en comparación con las personas de menor nivel educativo (sin escolaridad, primaria, secundaria y preparatoria. A su vez, se observó que la escolaridad de los padres influye en el locus de control. En términos generales, las variables que mejor predicen el locus de control fueron el ingreso familiar y la escolaridad de los sujetos

  13. Mating-type switching by chromosomal inversion in methylotrophic yeasts suggests an origin for the three-locus Saccharomyces cerevisiae system.

    Science.gov (United States)

    Hanson, Sara J; Byrne, Kevin P; Wolfe, Kenneth H

    2014-11-11

    Saccharomyces cerevisiae has a complex system for switching the mating type of haploid cells, requiring the genome to have three mating-type (MAT)-like loci and a mechanism for silencing two of them. How this system originated is unknown, because the three-locus system is present throughout the family Saccharomycetaceae, whereas species in the sister Candida clade have only one locus and do not switch. Here we show that yeasts in a third clade, the methylotrophs, have a simpler two-locus switching system based on reversible inversion of a section of chromosome with MATa genes at one end and MATalpha genes at the other end. In Hansenula polymorpha the 19-kb invertible region lies beside a centromere so that, depending on the orientation, either MATa or MATalpha is silenced by centromeric chromatin. In Pichia pastoris, the orientation of a 138-kb invertible region puts either MATa or MATalpha beside a telomere and represses transcription of MATa2 or MATalpha2. Both species are homothallic, and inversion of their MAT regions can be induced by crossing two strains of the same mating type. The three-locus system of S. cerevisiae, which uses a nonconservative mechanism to replace DNA at MAT, likely evolved from a conservative two-locus system that swapped genes between expression and nonexpression sites by inversion. The increasing complexity of the switching apparatus, with three loci, donor bias, and cell lineage tracking, can be explained by continuous selection to increase sporulation ability in young colonies. Our results provide an evolutionary context for the diversity of switching and silencing mechanisms.

  14. The C-terminal domain of CENP-C displays multiple and critical functions for mammalian centromere formation.

    Directory of Open Access Journals (Sweden)

    Stefania Trazzi

    2009-06-01

    Full Text Available CENP-C is a fundamental component of functional centromeres. The elucidation of its structure-function relationship with centromeric DNA and other kinetochore proteins is critical to the understanding of centromere assembly. CENP-C carries two regions, the central and the C-terminal domains, both of which are important for the ability of CENP-C to associate with the centromeric DNA. However, while the central region is largely divergent in CENP-C homologues, the C-terminal moiety contains two regions that are highly conserved from yeast to humans, named Mif2p homology domains (blocks II and III. The activity of these two domains in human CENP-C is not well defined. In this study we performed a functional dissection of C-terminal CENP-C region analyzing the role of single Mif2p homology domains through in vivo and in vitro assays. By immunofluorescence and Chromatin immunoprecipitation assay (ChIP we were able to elucidate the ability of the Mif2p homology domain II to target centromere and contact alpha satellite DNA. We also investigate the interactions with other conserved inner kinetochore proteins by means of coimmunoprecipitation and bimolecular fluorescence complementation on cell nuclei. We found that the C-terminal region of CENP-C (Mif2p homology domain III displays multiple activities ranging from the ability to form higher order structures like homo-dimers and homo-oligomers, to mediate interaction with CENP-A and histone H3. Overall, our findings support a model in which the Mif2p homology domains of CENP-C, by virtue of their ability to establish multiple contacts with DNA and centromere proteins, play a critical role in the structuring of kinethocore chromatin.

  15. Cell Biology of Cheating-Transmission of Centromeres and Other Selfish Elements Through Asymmetric Meiosis.

    Science.gov (United States)

    Chmátal, Lukáš; Schultz, Richard M; Black, Ben E; Lampson, Michael A

    2017-01-01

    Mendel's First Law of Genetics states that a pair of alleles segregates randomly during meiosis so that one copy of each is represented equally in gametes. Whereas male meiosis produces four equal sperm, in female meiosis only one cell, the egg, survives, and the others degenerate. Meiotic drive is a process in which a selfish DNA element exploits female meiotic asymmetry and segregates preferentially to the egg in violation of Mendel's First Law, thereby increasing its transmission to the offspring and frequency in a population. In principle, the selfish element can consist either of a centromere that increases its transmission via an altered kinetochore connection to the meiotic spindle or a centromere-like element that somehow bypasses the kinetochore altogether in doing so. There are now examples from eukaryotic model systems for both types of meiotic drive. Although meiotic drive has profound evolutionary consequences across many species, relatively little is known about the underlying mechanisms. We discuss examples in various systems and open questions about the underlying cell biology, and propose a mechanism to explain biased segregation in mammalian female meiosis.

  16. Organization and evolution of primate centromeric DNA from whole-genome shotgun sequence data.

    Science.gov (United States)

    Alkan, Can; Ventura, Mario; Archidiacono, Nicoletta; Rocchi, Mariano; Sahinalp, S Cenk; Eichler, Evan E

    2007-09-01

    The major DNA constituent of primate centromeres is alpha satellite DNA. As much as 2%-5% of sequence generated as part of primate genome sequencing projects consists of this material, which is fragmented or not assembled as part of published genome sequences due to its highly repetitive nature. Here, we develop computational methods to rapidly recover and categorize alpha-satellite sequences from previously uncharacterized whole-genome shotgun sequence data. We present an algorithm to computationally predict potential higher-order array structure based on paired-end sequence data and then experimentally validate its organization and distribution by experimental analyses. Using whole-genome shotgun data from the human, chimpanzee, and macaque genomes, we examine the phylogenetic relationship of these sequences and provide further support for a model for their evolution and mutation over the last 25 million years. Our results confirm fundamental differences in the dispersal and evolution of centromeric satellites in the Old World monkey and ape lineages of evolution.

  17. Characterization of the oncogenic function of centromere protein F in hepatocellular carcinoma

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Yongdong; Liu, Lulu; Zeng, Tingting; Zhu, Ying-Hui [State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou (China); Li, Jiangchao [Vascular Biology Research Institute, Guangdong Pharmaceutical University, Guangzhou (China); Chen, Leilei [Department of Clinical Oncology, The University of Hong Kong, Pokfulam, Hong Kong (China); Li, Yan; Yuan, Yun-Fei [State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou (China); Ma, Stephanie, E-mail: stefma@hku.hk [Department of Clinical Oncology, The University of Hong Kong, Pokfulam, Hong Kong (China); State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong (China); Guan, Xin-Yuan, E-mail: xyguan@hkucc.hku.hk [State Key Laboratory of Oncology in Southern China, Sun Yat-Sen University Cancer Center, Guangzhou (China); Department of Clinical Oncology, The University of Hong Kong, Pokfulam, Hong Kong (China); State Key Laboratory for Liver Research, The University of Hong Kong, Pokfulam, Hong Kong (China)

    2013-07-12

    Highlights: •Overexpression of CENPF is frequently detected in HCC. •Upregulation of CENPF serves as an independent prognosis factor in HCC patients. •CENPF functions as an oncogene in HCC by promoting cell G2/M transition. -- Abstract: Centromere protein F (CENPF) is an essential nuclear protein associated with the centromere-kinetochore complex and plays a critical role in chromosome segregation during mitosis. Up-regulation of CENPF expression has previously been detected in several solid tumors. In this study, we aim to study the expression and functional role of CENPF in hepatocellular carcinoma (HCC). We found CENPF was frequently overexpressed in HCC as compared with non-tumor tissue. Up-regulated CENPF expression in HCC was positively correlated with serum AFP, venous invasion, advanced differentiation stage and a shorter overall survival. Cox regression analysis found that overexpression of CENPF was an independent prognosis factor in HCC. Functional studies found that silencing CENPF could decrease the ability of the cells to proliferate, form colonies and induce tumor formation in nude mice. Silencing CENPF also resulted in the cell cycle arrest at G2/M checkpoint by down-regulating cell cycle proteins cdc2 and cyclin B1. Our data suggest that CENPF is frequently overexpressed in HCC and plays a critical role in driving HCC tumorigenesis.

  18. Pobreza y Locus de Control

    OpenAIRE

    Joaquina Palomar Lever; Laura M. Valdés Trejo

    2004-01-01

    En este trabajo se busco conocer si existen diferencias en el locus de control según el nivel de pobreza en una población de 900 personas clasificadas en tres grupos: pobres extremos, pobres moderados y no pobres. Los sujetos estudiados compartieron la característica de ser personas económicamente independientes. Para este estudio se utilizaron como instrumentos de medición, un cuestionario sociodemográfico y una escala de locus de control. Los resultados muestran que los grupos d...

  19. Analysis of human chromosome 21 for a locus conferring susceptibility to Hirschsprung Disease

    Energy Technology Data Exchange (ETDEWEB)

    Bolk, S.; Duggan, D.J.; Chakravarti, A. [Case Western Reserve Univ., Cleveland, OH (United States)

    1994-09-01

    It has been estimated that approximately 5% of patients diagnosed with Hirschsprung disease (HSCR), or aganglionic megacolon, have trisomy 21. Since the incidence of Hirschsprung disease is 1/5000 live births and the incidence of trisomy 21 is approximately 1/1000 live births, the observed occurrence of HSCR in trisomy 21 is fifty times higher than expected. We propose that at least one locus on chromosome 21 predisposes to HSCR. Although at fifty times elevated risk, only 1% of Down Syndrome cases have HSCR. Thus additional genes or genetic events are necessary for HSCR to manifest in patients with trisomy 21. Based on segregation analysis, Badner et al. postulated that recessive genes may be responsible for up to 80% of HSCR. We postulate that at least one such gene is on chromosome 21 and increased homozygosity for common recessive HSCR mutations may be one cause for the elevated risk of HSCR in cases of trisomy 21. To map such a chromosome 21 locus, we are searching for segments of human chromosome 21 which are identical by descent from the parent in whom non-disjunction occurred. These segments will arise either from meiosis I (followed by a crossover between the centromere and the locus) or from meiosis II (followed by no crossovers). Nine nuclear families with a proband diagnosed with HSCR and Down Syndrome have been genotyped for 18 microsatellite markers spanning human chromosome 21q. In all nine cases analyzed thus far, trisomy 21 resulted from maternal non-disjunction at meiosis I. At this point no single IBD region is apparent. Therefore, additional families are being ascertained and additional markers at high density are being genotyped to map the HSCR locus.

  20. Locus of control in graduation students

    OpenAIRE

    Haider Zaidi, Imran; MS (Clinical Psychology) Scholar G.C University, Faisalabad, Pakistan; Mohsin, M. Naeem; Director Distance Learning Education G.C University, Faisalabad, Pakistan

    2013-01-01

    The current research focused on exploring the direction of Locus of control as well as gender difference on locus of control among graduation students in Pakistan. A 29 item Locus of Control questionnaire (Rotter, 1966) was used to measure locus of control. Sample of (N=200) individuals (n=100) men and (n=100) women selected from different academic institutes of Faisalabad division Punjab Pakistan. Independent sample t-test was used for statistical analysis. This study has consistent results ...

  1. Sequence-specific physical properties of African green monkey alpha-satellite DNA contribute to centromeric heterochromatin formation

    NARCIS (Netherlands)

    Bussiek, M.; Hoischen, Christian; Diekmann, Stephan; Bennink, Martin L.

    2009-01-01

    Satellite DNA, a major component of eukaryotic centromeric heterochromatin, is potentially associated with the processes ensuring the faithful segregation of the genetic material during cell division. Structural properties of alpha-satellite DNA (AS) from African green monkey (AGM) were studied.

  2. A new family of satellite DNA sequences as a major component of centromeric heterochromatin in owls (Strigiformes).

    Science.gov (United States)

    Yamada, Kazuhiko; Nishida-Umehara, Chizuko; Matsuda, Yoichi

    2004-03-01

    We isolated a new family of satellite DNA sequences from HaeIII- and EcoRI-digested genomic DNA of the Blakiston's fish owl ( Ketupa blakistoni). The repetitive sequences were organized in tandem arrays of the 174 bp element, and localized to the centromeric regions of all macrochromosomes, including the Z and W chromosomes, and microchromosomes. This hybridization pattern was consistent with the distribution of C-band-positive centromeric heterochromatin, and the satellite DNA sequences occupied 10% of the total genome as a major component of centromeric heterochromatin. The sequences were homogenized between macro- and microchromosomes in this species, and therefore intraspecific divergence of the nucleotide sequences was low. The 174 bp element cross-hybridized to the genomic DNA of six other Strigidae species, but not to that of the Tytonidae, suggesting that the satellite DNA sequences are conserved in the same family but fairly divergent between the different families in the Strigiformes. Secondly, the centromeric satellite DNAs were cloned from eight Strigidae species, and the nucleotide sequences of 41 monomer fragments were compared within and between species. Molecular phylogenetic relationships of the nucleotide sequences were highly correlated with both the taxonomy based on morphological traits and the phylogenetic tree constructed by DNA-DNA hybridization. These results suggest that the satellite DNA sequence has evolved by concerted evolution in the Strigidae and that it is a good taxonomic and phylogenetic marker to examine genetic diversity between Strigiformes species.

  3. Identification of novel mitosis regulators through data mining with human centromere/kinetochore proteins as group queries

    Directory of Open Access Journals (Sweden)

    Tipton Aaron R

    2012-06-01

    Full Text Available Abstract Background Proteins functioning in the same biological pathway tend to be transcriptionally co-regulated or form protein-protein interactions (PPI. Multiple spatially and temporally regulated events are coordinated during mitosis to achieve faithful chromosome segregation. The molecular players participating in mitosis regulation are still being unravelled experimentally or using in silico methods. Results An extensive literature review has led to a compilation of 196 human centromere/kinetochore proteins, all with experimental evidence supporting the subcellular localization. Sixty-four were designated as “core” centromere/kinetochore components based on peak expression and/or well-characterized functions during mitosis. By interrogating and integrating online resources, we have mined for genes/proteins that display transcriptional co-expression or PPI with the core centromere/kinetochore components. Top-ranked hubs in either co-expression or PPI network are not only enriched with known mitosis regulators, but also contain candidates whose mitotic functions are not yet established. Experimental validation found that KIAA1377 is a novel centrosomal protein that also associates with microtubules and midbody; while TRIP13 is a novel kinetochore protein and directly interacts with mitotic checkpoint silencing protein p31comet. Conclusions Transcriptional co-expression and PPI network analyses with known human centromere/kinetochore proteins as a query group help identify novel potential mitosis regulators.

  4. A DNA polymerase alpha accessory protein, Mcl1, is required for propagation of centromere structures in fission yeast.

    Directory of Open Access Journals (Sweden)

    Toyoaki Natsume

    Full Text Available Specialized chromatin exists at centromeres and must be precisely transmitted during DNA replication. The mechanisms involved in the propagation of these structures remain elusive. Fission yeast centromeres are composed of two chromatin domains: the central CENP-A(Cnp1 kinetochore domain and flanking heterochromatin domains. Here we show that fission yeast Mcl1, a DNA polymerase alpha (Pol alpha accessory protein, is critical for maintenance of centromeric chromatin. In a screen for mutants that alleviate both central domain and outer repeat silencing, we isolated several cos mutants, of which cos1 is allelic to mcl1. The mcl1-101 mutation causes reduced CENP-A(Cnp1 in the central domain and an aberrant increase in histone acetylation in both domains. These phenotypes are also observed in a mutant of swi7(+, which encodes a catalytic subunit of Pol alpha. Mcl1 forms S-phase-specific nuclear foci, which colocalize with those of PCNA and Pol alpha. These results suggest that Mcl1 and Pol alpha are required for propagation of centromere chromatin structures during DNA replication.

  5. A cytogenetic study of hospital workers occupationally exposed to radionuclides in Serbia. Premature centromere division as novel biomarker of exposure?

    Energy Technology Data Exchange (ETDEWEB)

    Pajic, Jelena; Rakic, Boban [Serbian Institute of Occupational Health ' ' Dr Dragomir Karajovic' ' , Belgrade (Serbia). Biodosimetry Dept.; Jovicic, Dubravka [Univ. ' ' Singidunum' ' , Belgrade (Serbia). Genotoxicology Dept.; Milovanovic, Aleksandar [Serbian Institute of Occupational Health ' ' Dr Dragomir Karajovic' ' , Belgrade (Serbia). Biodosimetry Dept.; Belgrade Univ. (Serbia). Occupational Health Dept.

    2016-04-15

    The health risk of chronic exposure to radionuclides includes changes in the genome (e.g., chromosomal aberrations and micronuclei) that increase chromosomal instability. There are also other phenomena, which seem to appear more frequently in metaphases of exposed persons (such as premature centromere division). The aim of this study was to discover whether or not there is correlation between incidence of named cytogenetic changes in persons occupationally exposed to radionuclides in comparison with unexposed control group, and if significant correlation is determined, can premature centromere division be consider as a biomarker of radiation exposure? The exposed group comprised 50 individuals occupationally exposed to radionuclides. The reference control group consisted of 40 unexposed individuals. Chromosomal aberrations, micronuclei and premature centromere division were analyzed according to a standard International Atomic Energy Agency protocol. Statistical analyses were performed using SPSS 17.0 statistics.The means for analyzed cytogenetic changes were significantly higher in the exposed group. Positive correlation between them was found in exposed group. Premature centromere division parameter PCD5-10 was selected as particularly suitable for separating groups (exposed/unexposed). Identification of other phenomena related to radionuclide exposure, beside well known, may clarify recent problems in radiobiology concerning the biological response to low doses of ionizing radiation and its consequences.

  6. Linkage of Pfeiffer syndrome to chromosome 8 centromere and evidence for genetic heterogeneity.

    Science.gov (United States)

    Robin, N H; Feldman, G J; Mitchell, H F; Lorenz, P; Wilroy, R S; Zackai, E H; Allanson, J E; Reich, E W; Pfeiffer, R A; Clarke, L A

    1994-12-01

    Pfeiffer syndrome (PS) is an autosomal dominant disorder characterized by craniosynostosis, midfacial hypoplasia, and broad thumbs and great toes. We examined 129 individuals from 11 families with PS and performed linkage studies using microsatellite markers spanning the entire genome. Strongest support for linkage was with DNA markers (D8S255, GATA8G08) from chromosome 8. Obligate crossovers exclude close linkage to this region in six families, and there was significant evidence for genetic heterogeneity. A multipoint lod score of 7.15 was obtained in five families. The 11 cM interval between D8S278 and D8S285 contains one gene for PS and also spans the centromere of chromosome 8.

  7. Immunohistochemical Assessment of Expression of Centromere Protein—A (CENPA) in Human Invasive Breast Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Rajput, Ashish B. [Department of Pathology and Molecular Medicine, Queen' s University, Kingston, ON K7L 3N6 (Canada); Hu, Nianping [Cancer Research institute, Queen' s University, Kingston, ON K7L 3N6 (Canada); Varma, Sonal; Chen, Chien-Hung [Department of Pathology and Molecular Medicine, Queen' s University, Kingston, ON K7L 3N6 (Canada); Ding, Keyue [NCIC Clinical Trials Group, Queen' s University, Kingston, ON K7L 3N6 (Canada); Park, Paul C. [Department of Pathology and Molecular Medicine, Queen' s University, Kingston, ON K7L 3N6 (Canada); Chapman, Judy-Anne W. [NCIC Clinical Trials Group, Queen' s University, Kingston, ON K7L 3N6 (Canada); SenGupta, Sandip K. [Department of Pathology and Molecular Medicine, Queen' s University, Kingston, ON K7L 3N6 (Canada); Madarnas, Yolanda [Cancer Research institute, Queen' s University, Kingston, ON K7L 3N6 (Canada); Department of Oncology, Cancer Center of Southeastern Ontario, Kingston, ON K7L 2V7 (Canada); Elliott, Bruce E.; Feilotter, Harriet E., E-mail: feilotth@kgh.kari.net [Department of Pathology and Molecular Medicine, Queen' s University, Kingston, ON K7L 3N6 (Canada)

    2011-12-06

    Abnormal cell division leading to the gain or loss of entire chromosomes and consequent genetic instability is a hallmark of cancer. Centromere protein –A (CENPA) is a centromere-specific histone-H3-like variant gene involved in regulating chromosome segregation during cell division. CENPA is one of the genes included in some of the commercially available RNA based prognostic assays for breast cancer (BCa)—the 70 gene signature MammaPrint{sup ®} and the five gene Molecular Grade Index (MGI{sup SM}). Our aim was to assess the immunohistochemical (IHC) expression of CENPA in normal and malignant breast tissue. Clinically annotated triplicate core tissue microarrays of 63 invasive BCa and 20 normal breast samples were stained with a monoclonal antibody against CENPA and scored for percentage of visibly stained nuclei. Survival analyses with Kaplan–Meier (KM) estimate and Cox proportional hazards regression models were applied to assess the associations between CENPA expression and disease free survival (DFS). Average percentage of nuclei visibly stained with CENPA antibody was significantly higher (p = 0.02) in BCa than normal tissue. The 3-year DFS in tumors over-expressing CENPA (>50% stained nuclei) was 79% compared to 85% in low expression tumors (<50% stained nuclei). On multivariate analysis, IHC expression of CENPA showed weak association with DFS (HR > 60.07; p = 0.06) within our small cohort. To the best of our knowledge, this is the first published report evaluating the implications of increased IHC expression of CENPA in paraffin embedded breast tissue samples. Our finding that increased CENPA expression may be associated with shorter DFS in BCa supports its exploration as a potential prognostic biomarker.

  8. Centromeric alpha satellite DNA amplification and translocation in an unusually large chromosome 14p+ variant.

    Science.gov (United States)

    Dale, S; Earle, E; Voullaire, L; Rogers, J; Choo, K H

    1989-05-01

    We report cytogenetic and molecular studies on a family that carries, in the father, an unusually large chromosome 14p+ variant [WSi-var(14)(p+)] and, in one of his children, a translocation [DSi-der(14)] involving the variant chromosome. Increase in the size of WSi-var(14)(p+) was estimated to be approximately 35% that of a normal chromosome 14. Presence of extra chromosomal material in this variant chromosome was demonstrated by G-banding using trypsin and staining with Leishman, G-banding using bromodeoxyuridine (BrdU) and Giemsa, and R-banding using BrdU and Giemsa. This material was positive using C-banding with BaOH and staining with Giemsa and negative in DAPI/distamycin staining, suggesting that it contained repetitive DNA but probably not of the types found in the heterochromatic regions of chromosomes 1, 9, 15, 16, and Y. Staining of the nucleolus organiser region (NOR) with AgNO3 indicated the retention of the NOR in WSi-var(14)(p+) but not in DSi-der(14). In situ hybridisation of metaphase cells with an alpha satellite DNA probe specific for human acrocentric chromosomes demonstrated a significantly increased amount of centromeric alpha sequences in WSi-var(14)(p+). Most or all of the extra alpha sequences were retained in DSi-der(14), indicating translocation near the very distal end of the enlarged region. The extra alpha satellite DNA material may have originated through amplification of some centromeric segments. The possible role of the amplified DNA in chromosomal translocations is discussed.

  9. Immunohistochemical Assessment of Expression of Centromere Protein—A (CENPA in Human Invasive Breast Cancer

    Directory of Open Access Journals (Sweden)

    Bruce E. Elliott

    2011-12-01

    Full Text Available Abnormal cell division leading to the gain or loss of entire chromosomes and consequent genetic instability is a hallmark of cancer. Centromere protein –A (CENPA is a centromere-specific histone-H3-like variant gene involved in regulating chromosome segregation during cell division. CENPA is one of the genes included in some of the commercially available RNA based prognostic assays for breast cancer (BCa—the 70 gene signature MammaPrint® and the five gene Molecular Grade Index (MGISM. Our aim was to assess the immunohistochemical (IHC expression of CENPA in normal and malignant breast tissue. Clinically annotated triplicate core tissue microarrays of 63 invasive BCa and 20 normal breast samples were stained with a monoclonal antibody against CENPA and scored for percentage of visibly stained nuclei. Survival analyses with Kaplan–Meier (KM estimate and Cox proportional hazards regression models were applied to assess the associations between CENPA expression and disease free survival (DFS. Average percentage of nuclei visibly stained with CENPA antibody was significantly higher (p = 0.02 in BCa than normal tissue. The 3-year DFS in tumors over-expressing CENPA (>50% stained nuclei was 79% compared to 85% in low expression tumors ( 60.07; p = 0.06 within our small cohort. To the best of our knowledge, this is the first published report evaluating the implications of increased IHC expression of CENPA in paraffin embedded breast tissue samples. Our finding that increased CENPA expression may be associated with shorter DFS in BCa supports its exploration as a potential prognostic biomarker.

  10. Hybrid de novo genome assembly and centromere characterization of the gray mouse lemur (Microcebus murinus).

    Science.gov (United States)

    Larsen, Peter A; Harris, R Alan; Liu, Yue; Murali, Shwetha C; Campbell, C Ryan; Brown, Adam D; Sullivan, Beth A; Shelton, Jennifer; Brown, Susan J; Raveendran, Muthuswamy; Dudchenko, Olga; Machol, Ido; Durand, Neva C; Shamim, Muhammad S; Aiden, Erez Lieberman; Muzny, Donna M; Gibbs, Richard A; Yoder, Anne D; Rogers, Jeffrey; Worley, Kim C

    2017-11-16

    The de novo assembly of repeat-rich mammalian genomes using only high-throughput short read sequencing data typically results in highly fragmented genome assemblies that limit downstream applications. Here, we present an iterative approach to hybrid de novo genome assembly that incorporates datasets stemming from multiple genomic technologies and methods. We used this approach to improve the gray mouse lemur (Microcebus murinus) genome from early draft status to a near chromosome-scale assembly. We used a combination of advanced genomic technologies to iteratively resolve conflicts and super-scaffold the M. murinus genome. We improved the M. murinus genome assembly to a scaffold N50 of 93.32 Mb. Whole genome alignments between our primary super-scaffolds and 23 human chromosomes revealed patterns that are congruent with historical comparative cytogenetic data, thus demonstrating the accuracy of our de novo scaffolding approach and allowing assignment of scaffolds to M. murinus chromosomes. Moreover, we utilized our independent datasets to discover and characterize sequences associated with centromeres across the mouse lemur genome. Quality assessment of the final assembly found 96% of mouse lemur canonical transcripts nearly complete, comparable to other published high-quality reference genome assemblies. We describe a new assembly of the gray mouse lemur (Microcebus murinus) genome with chromosome-scale scaffolds produced using a hybrid bioinformatic and sequencing approach. The approach is cost effective and produces superior results based on metrics of contiguity and completeness. Our results show that emerging genomic technologies can be used in combination to characterize centromeres of non-model species and to produce accurate de novo chromosome-scale genome assemblies of complex mammalian genomes.

  11. A hemicentric inversion in the maize line knobless Tama flint created two sites of centromeric elements and moved the kinetochore-forming region.

    Science.gov (United States)

    Lamb, Jonathan C; Meyer, Julie M; Birchler, James A

    2007-06-01

    A maize line, knobless Tama flint (KTF), was found to contain a version of chromosome 8 with two spatially distinct regions of centromeric elements, one at the original genetic position and the other at a novel location on the long arm. The new site of centromeric elements functions as the kinetochore-forming region resulting in a change of arm length ratio. Examination of fluorescence in situ hybridization markers on chromosome 8 revealed an inversion between the two centromere sites relative to standard maize lines, indicating that this chromosome 8 resulted from a hemicentric inversion with one breakpoint approximately 20 centi-McClintocks (cMc) on the long arm (20% of the total arm length from the centromere) and the other in the original cluster of centromere repeats. This inversion moved the kinetochore-forming region but left the remainder of the centromere repeats. In a hybrid between a standard line (Mo17) and KTF, both chromosome 8 homologues were completely synapsed at pachytene despite the inversion. Although the homologous centromeres were not paired, they were always correctly oriented at anaphase and migrated to opposite poles. Additionally, recombination on 8L was severely repressed in the hybrid.

  12. Analysis of centromere structure in the fly Megaselia scalaris (Phoridae, Diptera) using CREST sera, anti-histone antibodies, and a repetitive DNA probe.

    Science.gov (United States)

    Wolf, K W; Mitchell, A; Nicol, L; Jeppesen, P

    1994-01-01

    We have used CREST anti-centromere sera, rabbit anti-histone antibodies, and repetitive DNA analysis to study centromere structure in the fly Megaselia scalaris (Phoridae). In a panel of eight CREST sera, four were positive in immunofluorescence experiments for prekinetochores, ie centromeres in interphase nuclei. The access of the antibodies to CREST antigens may be compromised in the condensed state, since centromeres of prometaphase and metaphase chromosomes remained unstained. When Western blots of embryonic nuclei were probed with these four CREST sera, three of them showed a 17 kDa band. Human CENP-A, likewise recognized by the CREST sera, is a 17 kDa protein. The remaining sera were negative for centromeres although some detected centrosomes and non-histone chromosomal proteins not confined to the centromeres. The use of antibodies generated against histone H4 acetylated at four different sites of the N-terminal domain revealed that heterochromatic regions of M scalaris mitotic chromosomes, ie pericentric and NOR-associated segments, are hyperacetylated. This is at variance with a variety of other systems, where transcriptionally active chromatin is hyperacetylated. Finally, a repetitive 165 base pair fragment was isolated from genomic DNA of the fly and sequenced. An oligonucleotide from this sequence mapped to the centromere region of interphase nuclei and the pericentric regions of condensed chromosomes.

  13. The cohesion protein SOLO associates with SMC1 and is required for synapsis, recombination, homolog bias and cohesion and pairing of centromeres in Drosophila Meiosis.

    Directory of Open Access Journals (Sweden)

    Rihui Yan

    Full Text Available Cohesion between sister chromatids is mediated by cohesin and is essential for proper meiotic segregation of both sister chromatids and homologs. solo encodes a Drosophila meiosis-specific cohesion protein with no apparent sequence homology to cohesins that is required in male meiosis for centromere cohesion, proper orientation of sister centromeres and centromere enrichment of the cohesin subunit SMC1. In this study, we show that solo is involved in multiple aspects of meiosis in female Drosophila. Null mutations in solo caused the following phenotypes: 1 high frequencies of homolog and sister chromatid nondisjunction (NDJ and sharply reduced frequencies of homolog exchange; 2 reduced transmission of a ring-X chromosome, an indicator of elevated frequencies of sister chromatid exchange (SCE; 3 premature loss of centromere pairing and cohesion during prophase I, as indicated by elevated foci counts of the centromere protein CID; 4 instability of the lateral elements (LEs and central regions of synaptonemal complexes (SCs, as indicated by fragmented and spotty staining of the chromosome core/LE component SMC1 and the transverse filament protein C(3G, respectively, at all stages of pachytene. SOLO and SMC1 are both enriched on centromeres throughout prophase I, co-align along the lateral elements of SCs and reciprocally co-immunoprecipitate from ovarian protein extracts. Our studies demonstrate that SOLO is closely associated with meiotic cohesin and required both for enrichment of cohesin on centromeres and stable assembly of cohesin into chromosome cores. These events underlie and are required for stable cohesion of centromeres, synapsis of homologous chromosomes, and a recombination mechanism that suppresses SCE to preferentially generate homolog crossovers (homolog bias. We propose that SOLO is a subunit of a specialized meiotic cohesin complex that mediates both centromeric and axial arm cohesion and promotes homolog bias as a component of

  14. Speaking rate effects on locus equation slope

    Science.gov (United States)

    Berry, Jeff; Weismer, Gary

    2013-01-01

    A locus equation describes a 1st order regression fit to a scatter of vowel steady-state frequency values predicting vowel onset frequency values. Locus equation coefficients are often interpreted as indices of coarticulation. Speaking rate variations with a constant consonant–vowel form are thought to induce changes in the degree of coarticulation. In the current work, the hypothesis that locus slope is a transparent index of coarticulation is examined through the analysis of acoustic samples of large-scale, nearly continuous variations in speaking rate. Following the methodological conventions for locus equation derivation, data pooled across ten vowels yield locus equation slopes that are mostly consistent with the hypothesis that locus equations vary systematically with coarticulation. Comparable analyses between different four-vowel pools reveal variations in the locus slope range and changes in locus slope sensitivity to rate change. Analyses across rate but within vowels are substantially less consistent with the locus hypothesis. Taken together, these findings suggest that the practice of vowel pooling exerts a non-negligible influence on locus outcomes. Results are discussed within the context of articulatory accounts of locus equations and the effects of speaking rate change. PMID:24535890

  15. A two-locus model of speciation.

    Science.gov (United States)

    Gregorius, H R

    1992-02-07

    Speciation is considered as the evolution of partial or complete cross-incompatibility between the carriers of genes (at a locus called "object locus") that distinguish the prospective species populations. The mating relations at the object locus are modified by the alleles at a second mating modifier locus. Based on a widely applicable concept of fitness and mating preference, it is shown that heterozygote disadvantage in fitness at the object locus is necessary for speciation, which corroborates Wallace's hypothesis. It is pointed out that the difference between sympatric and parapatric speciation essentially lies in the mechanisms stabilizing the polymorphism required at the object locus as a prerequisite for speciation. In the presence of recombination between the object and mating modifier locus speciation may be prevented by forces maintaining gametic phase imbalance between these loci such as can result from unidirectional gene flow between parapatric populations.

  16. Quantitative trait locus affecting birth weight on bovine chromosome 5 in a F2 Gyr x Holstein population

    Directory of Open Access Journals (Sweden)

    Gustavo Gasparin

    2005-12-01

    Full Text Available Segregation between a genetic marker and a locus influencing a quantitative trait in a well delineated population is the basis for success in mapping quantitative trait loci (QTL. To detect bovine chromosome 5 (BTA5 birth weight QTL we genotyped 294 F2 Gyr (Bos indicus x Holstein (Bos taurus crossbreed cattle for five microsatellite markers. A linkage map was constructed for the markers and an interval analysis for the presence of QTL was performed. The linkage map indicated differences in the order of two markers relative to the reference map (http://www.marc.usda.gov. Interval analysis detected a QTL controlling birth weight (p < 0.01 at 69 centimorgans (cM from the most centromeric marker with an effect of 0.32 phenotypic standard-error. These results support other studies with crossbred Bos taurus x Bos indicus populations.

  17. Budding yeast kinetochore proteins, Chl4 and Ctf19, are required to maintain SPB-centromere proximity during G1 and late anaphase.

    Directory of Open Access Journals (Sweden)

    Soumitra Sau

    Full Text Available In the budding yeast, centromeres stay clustered near the spindle pole bodies (SPBs through most of the cell cycle. This SPB-centromere proximity requires microtubules and functional kinetochores, which are protein complexes formed on the centromeres and capable of binding microtubules. The clustering is suggested by earlier studies to depend also on protein-protein interactions between SPB and kinetochore components. Previously it has been shown that the absence of non-essential kinetochore proteins of the Ctf19 complex weakens kinetochore-microtubule interaction, but whether this compromised interaction affects centromere/kinetochore positioning inside the nucleus is unknown. We found that in G1 and in late anaphase, SPB-centromere proximity was disturbed in mutant cells lacking Ctf19 complex members,Chl4p and/or Ctf19p, whose centromeres lay further away from their SPBs than those of the wild-type cells. We unequivocally show that the SPB-centromere proximity and distances are not dependent on physical interactions between SPB and kinetochore components, but involve microtubule-dependent forces only. Further insight on the positional difference between wild-type and mutant kinetochores was gained by generating computational models governed by (1 independently regulated, but constant kinetochore microtubule (kMT dynamics, (2 poleward tension on kinetochore and the antagonistic polar ejection force and (3 length and force dependent kMT dynamics. Numerical data obtained from the third model concurs with experimental results and suggests that the absence of Chl4p and/or Ctf19p increases the penetration depth of a growing kMT inside the kinetochore and increases the rescue frequency of a depolymerizing kMT. Both the processes result in increased distance between SPB and centromere.

  18. Budding Yeast Kinetochore Proteins, Chl4 and Ctf19, Are Required to Maintain SPB-Centromere Proximity during G1 and Late Anaphase

    Science.gov (United States)

    Sau, Soumitra; Sutradhar, Sabyasachi; Paul, Raja; Sinha, Pratima

    2014-01-01

    In the budding yeast, centromeres stay clustered near the spindle pole bodies (SPBs) through most of the cell cycle. This SPB-centromere proximity requires microtubules and functional kinetochores, which are protein complexes formed on the centromeres and capable of binding microtubules. The clustering is suggested by earlier studies to depend also on protein-protein interactions between SPB and kinetochore components. Previously it has been shown that the absence of non-essential kinetochore proteins of the Ctf19 complex weakens kinetochore-microtubule interaction, but whether this compromised interaction affects centromere/kinetochore positioning inside the nucleus is unknown. We found that in G1 and in late anaphase, SPB-centromere proximity was disturbed in mutant cells lacking Ctf19 complex members,Chl4p and/or Ctf19p, whose centromeres lay further away from their SPBs than those of the wild-type cells. We unequivocally show that the SPB-centromere proximity and distances are not dependent on physical interactions between SPB and kinetochore components, but involve microtubule-dependent forces only. Further insight on the positional difference between wild-type and mutant kinetochores was gained by generating computational models governed by (1) independently regulated, but constant kinetochore microtubule (kMT) dynamics, (2) poleward tension on kinetochore and the antagonistic polar ejection force and (3) length and force dependent kMT dynamics. Numerical data obtained from the third model concurs with experimental results and suggests that the absence of Chl4p and/or Ctf19p increases the penetration depth of a growing kMT inside the kinetochore and increases the rescue frequency of a depolymerizing kMT. Both the processes result in increased distance between SPB and centromere. PMID:25003500

  19. Holocentromeres in Rhynchospora are associated with genome-wide centromere-specific repeat arrays interspersed among euchromatin

    Czech Academy of Sciences Publication Activity Database

    Marques, A.; Ribeiro, T.; Neumann, Pavel; Macas, Jiří; Novák, Petr; Schubert, V.; Pellino, M.; Fuchs, J.; Ma, W.; Kuhlmann, M.; Brandt, R.; Vanzela, A.L.L.; Beseda, Tomáš; Šimková, Hana; Pedrosa-Harand, A.; Houben, A.

    2015-01-01

    Roč. 112, č. 44 (2015), s. 13633-13638 ISSN 0027-8424 R&D Projects: GA ČR GBP501/12/G090; GA MŠk(CZ) LO1204 Institutional support: RVO:60077344 ; RVO:61389030 Keywords : Centromere * satellite DNA * holokinetic * chromosome Subject RIV: EB - Genetics ; Molecular Biology; EB - Genetics ; Molecular Biology (UEB-Q) Impact factor: 9.423, year: 2015

  20. Comparison of Spinach Sex Chromosomes with Sugar Beet Autosomes Reveals Extensive Synteny and Low Recombination at the Male-Determining Locus.

    Science.gov (United States)

    Takahata, Satoshi; Yago, Takumi; Iwabuchi, Keisuke; Hirakawa, Hideki; Suzuki, Yutaka; Onodera, Yasuyuki

    2016-01-01

    Spinach (Spinacia oleracea, 2n = 12) and sugar beet (Beta vulgaris, 2n = 18) are important crop members of the family Chenopodiaceae ss Sugar beet has a basic chromosome number of 9 and a cosexual breeding system, as do most members of the Chenopodiaceae ss. family. By contrast, spinach has a basic chromosome number of 6 and, although certain cultivars and genotypes produce monoecious plants, is considered to be a dioecious species. The loci determining male and monoecious sexual expression were mapped to different loci on the spinach sex chromosomes. In this study, a linkage map with 46 mapped protein-coding sequences was constructed for the spinach sex chromosomes. Comparison of the linkage map with a reference genome sequence of sugar beet revealed that the spinach sex chromosomes exhibited extensive synteny with sugar beet chromosomes 4 and 9. Tightly linked protein-coding genes linked to the male-determining locus in spinach corresponded to genes located in or around the putative pericentromeric and centromeric regions of sugar beet chromosomes 4 and 9, supporting the observation that recombination rates were low in the vicinity of the male-determining locus. The locus for monoecism was confined to a chromosomal segment corresponding to a region of approximately 1.7Mb on sugar beet chromosome 9, which may facilitate future positional cloning of the locus. © The American Genetic Association 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  1. An Alternatively Spliced Bifunctional Localization Signal Reprograms Human Shugoshin 1 to Protect Centrosomal Instead of Centromeric Cohesin

    Directory of Open Access Journals (Sweden)

    Lisa Mohr

    2015-09-01

    Full Text Available Separation of human sister chromatids involves the removal of DNA embracing cohesin ring complexes. Ring opening occurs by prophase-pathway-dependent phosphorylation and separase-mediated cleavage, with the former being antagonized at centromeres by Sgo1-dependent PP2A recruitment. Intriguingly, prophase pathway signaling and separase’s proteolytic activity also bring about centriole disengagement, whereas Sgo1 is again counteracting this licensing step of later centrosome duplication. Here, we demonstrate that alternative splice variants of human Sgo1 specifically and exclusively localize and function either at centromeres or centrosomes. A small C-terminal peptide encoded by exon 9 of SGO1 (CTS for centrosomal targeting signal of human Sgo1 is necessary and sufficient to drive centrosomal localization and simultaneously abrogate centromeric association of corresponding Sgo1 isoforms. Cohesin is shown to be a target of the prophase pathway at centrosomes and protected by Sgo1-PP2A. Accordingly, premature centriole disengagement in response to Sgo1 depletion is suppressed by blocking ring opening of an engineered cohesin.

  2. An Iml3-Chl4 Heterodimer Links the Core Centromere to Factors Required for Accurate Chromosome Segregation

    Directory of Open Access Journals (Sweden)

    Stephen M. Hinshaw

    2013-10-01

    Full Text Available Accurate segregation of genetic material in eukaryotes relies on the kinetochore, a multiprotein complex that connects centromeric DNA with microtubules. In yeast and humans, two proteins—Mif2/CENP-C and Chl4/CNEP-N—interact with specialized centromeric nucleosomes and establish distinct but cross-connecting axes of chromatin-microtubule linkage. Proteins recruited by Chl4/CENP-N include a subset that regulates chromosome transmission fidelity. We show that Chl4 and a conserved member of this subset, Iml3, both from Saccharomyces cerevisiae, form a stable protein complex that interacts with Mif2 and Sgo1. We have determined the structures of an Iml3 homodimer and an Iml3-Chl4 heterodimer, which suggest a mechanism for regulating the assembly of this functional axis of the kinetochore. We propose that at the core centromere, the Chl4-Iml3 complex participates in recruiting factors, such as Sgo1, that influence sister chromatid cohesion and encourage sister kinetochore biorientation.

  3. Evidence for multiple alleles at the DGAT1 locus better explains a quantitative trait locus with major effect on milk fat content in cattle.

    Science.gov (United States)

    Kühn, Christa; Thaller, Georg; Winter, Andreas; Bininda-Emonds, Olaf R P; Kaupe, Bernhard; Erhardt, Georg; Bennewitz, Jörn; Schwerin, Manfred; Fries, Ruedi

    2004-08-01

    A quantitative trait locus (QTL) for milk fat percentage has been mapped consistently to the centromeric region of bovine chromosome 14 (BTA14). Two independent studies have identified the nonconservative mutation K232A in the acylCoA-diacylglycerol-acyltransferase 1 (DGAT1) gene as likely to be causal for the observed variation. Here we provide evidence for additional genetic variability at the same QTL that is associated with milk fat percentage variation within the German Holstein population. Namely, we show that alleles of the DGAT1 promoter derived from the variable number of tandem repeat (VNTR) polymorphism are associated with milk fat content in animals homozygous for the allele 232A at DGAT1. Our results present another example for more than two trait-associated alleles being involved in a major gene effect on a quantitative trait. The segregation of multiple alleles affecting milk production traits at the QTL on BTA14 has to be considered whenever marker-assisted selection programs are implemented in dairy cattle. Due to the presence of a potential transcription factor binding site in the 18mer element of the VNTR, the variation in the number of tandem repeats of the 18mer element might be causal for the variability in the transcription level of the DGAT1 gene. Copyright 2004 Genetics Society of America

  4. A transcriptomic analysis of human centromeric and pericentric sequences in normal and tumor cells

    Science.gov (United States)

    Eymery, Angéline; Horard, Béatrice; Atifi-Borel, Michèle El; Fourel, Geneviève; Berger, François; Vitte, Anne-Laure; Van den Broeck, Arnaud; Brambilla, Elisabeth; Fournier, Alexandra; Callanan, Mary; Gazzeri, Sylvie; Khochbin, Saadi; Rousseaux, Sophie; Gilson, Eric; Vourc’h, Claire

    2009-01-01

    Although there is now evidence that the expression of centromeric (CT) and pericentric (PCT) sequences are key players in major genomic functions, their transcriptional status in human cells is still poorly known. The main reason for this lack of data is the complexity and high level of polymorphism of these repeated sequences, which hampers straightforward analyses by available transcriptomic approaches. Here a transcriptomic macro-array dedicated to the analysis of CT and PCT expression is developed and validated in heat-shocked (HS) HeLa cells. For the first time, the expression status of CT and PCT sequences is analyzed in a series of normal and cancer human cells and tissues demonstrating that they are repressed in all normal tissues except in the testis, where PCT transcripts are found. Moreover, PCT sequences are specifically expressed in HS cells in a Heat-Shock Factor 1 (HSF1)-dependent fashion, and we show here that another independent pathway, involving DNA hypo-methylation, can also trigger their expression. Interestingly, CT and PCT were found illegitimately expressed in somatic cancer samples, whereas PCT were repressed in testis cancer, suggesting that the expression of CT and PCT sequences may represent a good indicator of epigenetic deregulations occurring in response to environmental changes or in cell transformation. PMID:19720732

  5. Recent amplification of the kangaroo endogenous retrovirus, KERV, limited to the centromere.

    Science.gov (United States)

    Ferreri, Gianni C; Brown, Judith D; Obergfell, Craig; Jue, Nathaniel; Finn, Caitlin E; O'Neill, Michael J; O'Neill, Rachel J

    2011-05-01

    Mammalian retrotransposons, transposable elements that are processed through an RNA intermediate, are categorized as short interspersed elements (SINEs), long interspersed elements (LINEs), and long terminal repeat (LTR) retroelements, which include endogenous retroviruses. The ability of transposable elements to autonomously amplify led to their initial characterization as selfish or junk DNA; however, it is now known that they may acquire specific cellular functions in a genome and are implicated in host defense mechanisms as well as in genome evolution. Interactions between classes of transposable elements may exert a markedly different and potentially more significant effect on a genome than interactions between members of a single class of transposable elements. We examined the genomic structure and evolution of the kangaroo endogenous retrovirus (KERV) in the marsupial genus Macropus. The complete proviral structure of the kangaroo endogenous retrovirus, phylogenetic relationship among relative retroviruses, and expression of this virus in both Macropus rufogriseus and M. eugenii are presented for the first time. In addition, we show the relative copy number and distribution of the kangaroo endogenous retrovirus in the Macropus genus. Our data indicate that amplification of the kangaroo endogenous retrovirus occurred in a lineage-specific fashion, is restricted to the centromeres, and is not correlated with LINE depletion. Finally, analysis of KERV long terminal repeat sequences using massively parallel sequencing indicates that the recent amplification in M. rufogriseus is likely due to duplications and concerted evolution rather than a high number of independent insertion events.

  6. Differential Chromosomal Localization of Centromeric Histone CENP-A Contributes to Nematode Programmed DNA Elimination

    Directory of Open Access Journals (Sweden)

    Yuanyuan Kang

    2016-08-01

    Full Text Available The stability of the genome is paramount to organisms. However, diverse eukaryotes carry out programmed DNA elimination in which portions or entire chromsomes are lost in early development or during sex determination. During early development of the parasitic nematode, Ascaris suum, 13% of the genome is eliminated. How different genomic segments are reproducibly retained or discarded is unknown. Here, we show that centromeric histone CENP-A localization plays a key role in this process. We show that Ascaris chromosomes are holocentric during germline mitoses, with CENP-A distributed along their length. Prior to DNA elimination in the four-cell embryo, CENP-A is significantly diminished in chromosome regions that will be lost. This leads to the absence of kinetochores and microtubule attachment sites necessary for chromosome segregation, resulting in loss of these regions upon mitosis. Our data suggest that changes in CENP-A localization specify which portions of chromosomes will be lost during programmed DNA elimination.

  7. Centromere protein F includes two sites that couple efficiently to depolymerizing microtubules.

    Science.gov (United States)

    Volkov, Vladimir A; Grissom, Paula M; Arzhanik, Vladimir K; Zaytsev, Anatoly V; Renganathan, Kutralanathan; McClure-Begley, Tristan; Old, William M; Ahn, Natalie; McIntosh, J Richard

    2015-06-22

    Firm attachments between kinetochores and dynamic spindle microtubules (MTs) are important for accurate chromosome segregation. Centromere protein F (CENP-F) has been shown to include two MT-binding domains, so it may participate in this key mitotic process. Here, we show that the N-terminal MT-binding domain of CENP-F prefers curled oligomers of tubulin relative to MT walls by approximately fivefold, suggesting that it may contribute to the firm bonds between kinetochores and the flared plus ends of dynamic MTs. A polypeptide from CENP-F's C terminus also bound MTs, and either protein fragment diffused on a stable MT wall. They also followed the ends of dynamic MTs as they shortened. When either fragment was coupled to a microbead, the force it could transduce from a shortening MT averaged 3-5 pN but could exceed 10 pN, identifying CENP-F as a highly effective coupler to shortening MTs. © 2015 Volkov et al.

  8. Relevance of Cd-banding and premature centromere division in human metaphase figures

    Energy Technology Data Exchange (ETDEWEB)

    Verschaeve, L.; Defoin, A.; Staessen, K.; Kirsch-Volders, M.

    1986-01-01

    Kinetochore-inactivation as one of the possible mechanisms for aneuploidy was studied in human lymphocytes by two, possibly related, cytogenetic techniques: Cd-banding and premature centromere division (PCD). Cd-banding is a particular staining procedure which is presently admitted to allow discrimination between active and inactive (or absent) kinetochores. PCD is considered to be one of the consequences of kinetochore-inactivation and the origin of at least some aneuploidy. At first a confined study in monozygotic- and dizygotic twins did not reveal that Cd-stainability and PCD are heritable characters. In a second approach they studied the possible role of inactivated kinetochores in aneuploidy produced after exposure of lymphocytes to aneuploidy-inducing substances. It was shown that carbaryl, methylmercury chloride, mercury chloride and arsenic trioxide did not increase the frequency of metaphase figures with Cd-negative and PCD-chromosomes. Therefore, kinetochore-inactivation does not seem to contribute to the known aneuploidy induction of these compounds. As it is known that chromosome segregational errors are very often responsible for early miscarriages, they also investigated some couples with recurrent abortions. Their results indicate that kinetochore-inactivation is apparently not responsible for their abortive conceptions.

  9. How the kinetochore couples microtubule force and centromere stretch to move chromosomes

    Science.gov (United States)

    Suzuki, Aussie; Badger, Benjamin L.; Haase, Julian; Ohashi, Tomoo; Erickson, Harold P.; Salmon, Edward D.; Bloom, Kerry

    2016-01-01

    Summary The Ndc80 complex (Ndc80, Nuf2, Spc24, Spc25) is a highly conserved kinetochore protein essential for end-on anchorage to spindle microtubule plus-ends and for force generation coupled to plus-end polymerization and depolymerization. Spc24/Spc25 at one end of the Ndc80 complex binds the kinetochore. The N-terminal tail and CH domains of Ndc80 bind microtubules, and an internal domain binds microtubule-associated proteins (MAPs) such as the Dam1 complex. To determine how the microtubule and MAP binding domains of Ndc80 contribute to force production at the kinetochore in budding yeast, we have inserted a FRET tension sensor into the Ndc80 protein about halfway between its microtubule binding and internal loop domains. The data support a mechanical model of force generation at metaphase where the position of the kinetochore relative to the microtubule plus-end reflects the relative strengths of microtubule depolymerization, centromere stretch and microtubule binding interactions with Ndc80 and Dam1 complexes. PMID:26974660

  10. Centromere pairing by a plasmid-encoded type I ParB protein

    DEFF Research Database (Denmark)

    Ringgaard, Simon; Löwe, Jan; Gerdes, Kenn

    2007-01-01

    The par2 locus of Escherichia coli plasmid pB171 encodes two trans-acting proteins, ParA and ParB, and two cis-acting sites, parC1 and parC2, to which ParB binds cooperatively. ParA is related to MinD and oscillates in helical structures and thereby positions ParB/parC-carrying plasmids regularly...

  11. Locus of Control and Religious Orientation.

    Science.gov (United States)

    Talbott, Anne Marie; Heritage, Jeannette

    Rotter's Internal-External Locus of Control Scale has been the focus of much research since its introduction in 1966. To further that research, the relationships among locus of control, level of religious belief, attitudes toward women, attitudes toward feminism, attitudes toward homosexuality, gender, and traditional versus nontraditional…

  12. Epigenetic Histone Marks of Extended Meta-Polycentric Centromeres of Lathyrus and Pisum Chromosomes

    Science.gov (United States)

    Neumann, Pavel; Schubert, Veit; Fuková, Iva; Manning, Jasper E.; Houben, Andreas; Macas, Jiří

    2016-01-01

    Species of the legume genera Lathyrus and Pisum possess chromosomes that exhibit a unique structure of their centromeric regions, which is clearly apparent during metaphase by the formation of extended primary constrictions which span up to a third of the length of the chromosome. In addition, these species express two different variants of the CenH3 protein which are co-localized in multiple domains along the poleward surface of the primary constrictions. Here, we show that the constrictions represent a distinct type of chromatin differing from the chromosome arms. In metaphase, histone phosphorylation patterns including H3S10ph, H3S28ph, and H3T3ph were observed along the entire constriction, in a way similar to holocentric chromosomes. On the other hand, distribution of phosphorylated H2AT120 was different from that previously reported from either, holocentric and monocentric chromosomes, occurring at chromatin surrounding but not overlapping CenH3 domains. Since some of these phosphorylations play a role in chromatid cohesion, it can be assumed that they facilitate correct chromosome segregation by ensuring that multiple separate CenH3 domains present on the same chromatid are oriented toward the same pole. The constrictions also displayed distinct patterns of histone methylation marks, being enriched in H3K9me2 and depleted in H3K4me3 and H3K27me2 compared to the chromosome arms. Super-resolution fluorescence microscopy revealed that although both CenH3 protein variants are present in all CenH3 domains detected on metaphase chromosomes, they are only partially co-localized while there are chromatin subdomains which are mostly made of only one CenH3 variant. Taken together, these data revealed specific features of extended primary constrictions of Lathyrus and Pisum and support the idea that they may represent an intermediate stage between monocentric and holocentric chromosomes. PMID:26973677

  13. Prognostic significance of centromere 17 copy number gain in breast cancer depends on breast cancer subtype.

    Science.gov (United States)

    Lee, Kyuongyul; Jang, Min Hye; Chung, Yul Ri; Lee, Yangkyu; Kang, Eunyoung; Kim, Sung-Won; Kim, Yu Jung; Kim, Jee Hyun; Kim, In Ah; Park, So Yeon

    2017-03-01

    Increased copy number of chromosome enumeration probe (CEP) targeting centromere 17 is frequently encountered during HER2 in situ hybridization (ISH) in breast cancer. The aim of this study was to clarify the clinicopathologic significance of CEP17 copy number gain in a relatively large series of breast cancer patients. We analyzed 945 cases of invasive breast cancers whose HER2 fluorescence ISH reports were available from 2004 to 2011 at a single institution and evaluated the association of CEP17 copy number gain with clinicopathologic features of tumors and patient survival. We detected 186 (19.7%) cases of CEP17 copy number gain (CEP17≥3.0) among 945 invasive breast cancers. In survival analysis, CEP17 copy number gain was not associated with disease-free survival of the patients in the whole group. Nonetheless, it was found to be an independent adverse prognostic factor in the HER2-negative group but not in the HER2-positive group. In further subgroup analyses, CEP17 copy number gain was revealed as an independent poor prognostic factor in HER2-negative and hormone receptor-positive breast cancers, and it was associated with aggressive histologic variables including high T stage, high histologic grade, lymphovascular invasion, p53 overexpression, and high Ki-67 proliferative index. In conclusion, we found that elevated CEP17 count can serve as a prognostic marker in luminal/HER2-negative subtype of invasive breast cancer. We advocate the use of the dual-colored fluorescence ISH using CEP17 rather than the single-colored one because it gives additional valuable information on CEP17 copy number alterations. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. EL LOCUS DE DISTRIBUCION COMO COROLARIO DEL LOCUS DE CONTROL

    Directory of Open Access Journals (Sweden)

    Luisa Mayoral

    2009-01-01

    Full Text Available Este es un artículo científico acerca del Locus de Distribución, surgido de un estudio realizado con una población de docentes y alumnos universitarios. Respecto de los primeros, se ha indagado acerca de las atribuciones que se realizaban en torno a las recompensas y sanciones, que ellos distribuían a sus alumnos. Respecto de los segundos, se ha buscado determinar la valoración que estos realizaban de sus profesores, en términos de aquellas atribuciones. Para ello, se utilizaron dos paradigmas clásicamente empleados para verificar la existencia de una norma: el paradigma de la autopresentación (docentes, y el paradigma de los juicios (alumnos. La cuestión planteada fue determinar si en el caso de los comportamientos distributivos de refuerzos, las causas se atribuían a variables externas -en particular a los receptores de esos refuerzos- y si esas formas de atribución eran conocidas y valoradas o no, por los alumnos. De los resultados, surgió la confirmación de nuestra hipótesis de explicaciones externas en materia de comportamientos distributivos de sanciones en el ámbito de la docencia y la valoración positiva de estas atribuciones por los alumnos.

  15. KAT7/HBO1/MYST2 Regulates CENP-A Chromatin Assembly by Antagonizing Suv39h1-Mediated Centromere Inactivation.

    Science.gov (United States)

    Ohzeki, Jun-Ichirou; Shono, Nobuaki; Otake, Koichiro; Martins, Nuno M C; Kugou, Kazuto; Kimura, Hiroshi; Nagase, Takahiro; Larionov, Vladimir; Earnshaw, William C; Masumoto, Hiroshi

    2016-06-06

    Centromere chromatin containing histone H3 variant CENP-A is required for accurate chromosome segregation as a foundation for kinetochore assembly. Human centromere chromatin assembles on a part of the long α-satellite (alphoid) DNA array, where it is flanked by pericentric heterochromatin. Heterochromatin spreads into adjacent chromatin and represses gene expression, and it can antagonize centromere function or CENP-A assembly. Here, we demonstrate an interaction between CENP-A assembly factor M18BP1 and acetyltransferase KAT7/HBO1/MYST2. Knocking out KAT7 in HeLa cells reduced centromeric CENP-A assembly. Mitotic chromosome misalignment and micronuclei formation increased in the knockout cells and were enhanced when the histone H3-K9 trimethylase Suv39h1 was overproduced. Tethering KAT7 to an ectopic alphoid DNA integration site removed heterochromatic H3K9me3 modification and was sufficient to stimulate new CENP-A or histone H3.3 assembly. Thus, KAT7-containing acetyltransferases associating with the Mis18 complex provides competence for histone turnover/exchange activity on alphoid DNA and prevents Suv39h1-mediated heterochromatin invasion into centromeres. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Localization and Function of Budding Yeast CENP-A Depends upon Kinetochore Protein Interactions and Is Independent of Canonical Centromere Sequence

    Directory of Open Access Journals (Sweden)

    Kung-Hsien Ho

    2014-12-01

    Full Text Available In many eukaryotes, the centromere is epigenetically specified and not strictly defined by sequence. In contrast, budding yeast has a specific 125 bp sequence required for kinetochore function. Despite the difference in centromere specification, budding yeast and multicellular eukaryotic centromeres contain a highly conserved histone H3 variant, CENP-A. The localization of budding yeast CENP-A, Cse4, requires the centromere DNA binding components, which are not conserved in multicellular eukaryotes. Here, we report that Cse4 localizes and functions at a synthetic kinetochore assembly site that lacks centromere sequence. The outer kinetochore Dam1-DASH and inner kinetochore CBF3 complexes are required for Cse4 localization to that site. Furthermore, the natural kinetochore also requires the outer kinetochore proteins for full Cse4 localization. Our results suggest that Cse4 localization at a functional kinetochore does not require the recognition of a specific DNA sequence by the CBF3 complex; rather, its localization depends on stable interactions among kinetochore proteins.

  17. Genetics and biology of human ovarian teratomas. II. Molecular analysis of origin of nondisjunction and gene-centromere mapping of chromosome I markers.

    Science.gov (United States)

    Deka, R; Chakravarti, A; Surti, U; Hauselman, E; Reefer, J; Majumder, P P; Ferrell, R E

    1990-10-01

    Chromosomal heteromorphisms and DNA polymorphisms have been utilized to identify the mechanisms that lead to formation of human ovarian teratomas and to construct a gene-centromere map of chromosome 1 by using those teratomas that arise by meiotic nondisjunction. Of 61 genetically informative ovarian teratomas, 21.3% arose by nondisjunction at meiosis I, and 39.3% arose by meiosis II nondisjunction. Eight polymorphic marker loci on chromosome 1p and one marker on 1q were used to estimate a gene-centromere map. The results show clear linkage of the most proximal 1p marker (NRAS) and the most proximal 1q marker (D1S61) to the centromere at a distance of 14 cM and 20 cM, respectively. Estimated gene-centromere distances suggest that, while recombination occurs normally in ovarian teratomas arising by meiosis II errors, ovarian teratomas arising by meiosis I nondisjunction have altered patterns of recombination. Furthermore, the estimated map demonstrates clear evidence of chiasma interference. Our results suggest that ovarian teratomas can provide a rapid method for mapping genes relative to the centromere.

  18. The N-Terminal Non-Kinase-Domain-Mediated Binding of Haspin to Pds5B Protects Centromeric Cohesion in Mitosis.

    Science.gov (United States)

    Zhou, Linli; Liang, Cai; Chen, Qinfu; Zhang, Zhenlei; Zhang, Bo; Yan, Haiyan; Qi, Feifei; Zhang, Miao; Yi, Qi; Guan, Youchen; Xiang, Xingfeng; Zhang, Xiaoqing; Ye, Sheng; Wang, Fangwei

    2017-04-03

    Sister-chromatid cohesion, mediated by the multi-subunit cohesin complex, must be precisely regulated to prevent chromosome mis-segregation. In prophase and prometaphase, whereas the bulk of cohesin on chromosome arms is removed by its antagonist Wapl, cohesin at centromeres is retained to ensure chromosome biorientation until anaphase onset. It remains incompletely understood how centromeric cohesin is protected against Wapl in mitosis. Here we show that the mitotic histone kinase Haspin binds to the cohesin regulatory subunit Pds5B through a conserved YGA/R motif in its non-catalytic N terminus, which is similar to the recently reported YSR-motif-dependent binding of Wapl to Pds5B. Knockout of Haspin or disruption of Haspin-Pds5B interaction causes weakened centromeric cohesion and premature chromatid separation, which can be reverted by centromeric targeting of a N-terminal short fragment of Haspin containing the Pds5B-binding motif or by prevention of Wapl-dependent cohesin removal. Conversely, excessive Haspin capable of binding Pds5B displaces Wapl from Pds5B and suppresses Wapl activity, and it largely bypasses the Wapl antagonist Sgo1 for cohesion protection. Taken together, these data indicate that the Haspin-Pds5B interaction is required to ensure proper sister-chromatid cohesion, most likely through antagonizing Wapl-mediated cohesin release from mitotic centromeres. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. High Throughput Analyses of Budding Yeast ARSs Reveal New DNA Elements Capable of Conferring Centromere-Independent Plasmid Propagation

    Directory of Open Access Journals (Sweden)

    Timothy Hoggard

    2016-04-01

    Full Text Available The ability of plasmids to propagate in Saccharomyces cerevisiae has been instrumental in defining eukaryotic chromosomal control elements. Stable propagation demands both plasmid replication, which requires a chromosomal replication origin (i.e., an ARS, and plasmid distribution to dividing cells, which requires either a chromosomal centromere for segregation or a plasmid-partitioning element. While our knowledge of yeast ARSs and centromeres is relatively advanced, we know less about chromosomal regions that can function as plasmid partitioning elements. The Rap1 protein-binding site (RAP1 present in transcriptional silencers and telomeres of budding yeast is a known plasmid-partitioning element that functions to anchor a plasmid to the inner nuclear membrane (INM, which in turn facilitates plasmid distribution to daughter cells. This Rap1-dependent INM-anchoring also has an important chromosomal role in higher-order chromosomal structures that enhance transcriptional silencing and telomere stability. Thus, plasmid partitioning can reflect fundamental features of chromosome structure and biology, yet a systematic screen for plasmid partitioning elements has not been reported. Here, we couple deep sequencing with competitive growth experiments of a plasmid library containing thousands of short ARS fragments to identify new plasmid partitioning elements. Competitive growth experiments were performed with libraries that differed only in terms of the presence or absence of a centromere. Comparisons of the behavior of ARS fragments in the two experiments allowed us to identify sequences that were likely to drive plasmid partitioning. In addition to the silencer RAP1 site, we identified 74 new putative plasmid-partitioning motifs predicted to act as binding sites for DNA binding proteins enriched for roles in negative regulation of gene expression and G2/M-phase associated biology. These data expand our knowledge of chromosomal elements that may

  20. Translocations affecting human immunoglobulin heavy chain locus

    Directory of Open Access Journals (Sweden)

    Sklyar I. V.

    2014-03-01

    Full Text Available Translocations involving human immunoglobulin heavy chain (IGH locus are implicated in different leukaemias and lymphomas, including multiple myeloma, mantle cell lymphoma, Burkitt’s lymphoma and diffuse large B cell lymphoma. We have analysed published data and identified eleven breakpoint cluster regions (bcr related to these cancers within the IgH locus. These ~1 kbp bcrs are specific for one or several types of blood cancer. Our findings could help devise PCR-based assays to detect cancer-related translocations, to identify the mechanisms of translocations and to help in the research of potential translocation partners of the immunoglobulin locus at different stages of B-cell differentiation.

  1. Fine-Mapping of the 1p11.2 Breast Cancer Susceptibility Locus

    Science.gov (United States)

    Horne, Hisani N.; Chung, Charles C.; Zhang, Han; Yu, Kai; Prokunina-Olsson, Ludmila; Michailidou, Kyriaki; Bolla, Manjeet K.; Wang, Qin; Dennis, Joe; Hopper, John L.; Southey, Melissa C.; Schmidt, Marjanka K.; Broeks, Annegien; Muir, Kenneth; Lophatananon, Artitaya; Fasching, Peter A.; Beckmann, Matthias W.; Fletcher, Olivia; Johnson, Nichola; Sawyer, Elinor J.; Tomlinson, Ian; Burwinkel, Barbara; Marme, Frederik; Guénel, Pascal; Truong, Thérèse; Bojesen, Stig E.; Flyger, Henrik; Benitez, Javier; González-Neira, Anna; Anton-Culver, Hoda; Neuhausen, Susan L.; Brenner, Hermann; Arndt, Volker; Meindl, Alfons; Schmutzler, Rita K.; Brauch, Hiltrud; Hamann, Ute; Nevanlinna, Heli; Khan, Sofia; Matsuo, Keitaro; Iwata, Hiroji; Dörk, Thilo; Bogdanova, Natalia V.; Lindblom, Annika; Margolin, Sara; Mannermaa, Arto; Kosma, Veli-Matti; Chenevix-Trench, Georgia; Wu, Anna H.; ven den Berg, David; Smeets, Ann; Zhao, Hui; Chang-Claude, Jenny; Rudolph, Anja; Radice, Paolo; Barile, Monica; Couch, Fergus J.; Vachon, Celine; Giles, Graham G.; Milne, Roger L.; Haiman, Christopher A.; Marchand, Loic Le; Goldberg, Mark S.; Teo, Soo H.; Taib, Nur A. M.; Kristensen, Vessela; Borresen-Dale, Anne-Lise; Zheng, Wei; Shrubsole, Martha; Winqvist, Robert; Jukkola-Vuorinen, Arja; Andrulis, Irene L.; Knight, Julia A.; Devilee, Peter; Seynaeve, Caroline; García-Closas, Montserrat; Czene, Kamila; Darabi, Hatef; Hollestelle, Antoinette; Martens, John W. M.; Li, Jingmei; Lu, Wei; Shu, Xiao-Ou; Cox, Angela; Cross, Simon S.; Blot, William; Cai, Qiuyin; Shah, Mitul; Luccarini, Craig; Baynes, Caroline; Harrington, Patricia; Kang, Daehee; Choi, Ji-Yeob; Hartman, Mikael; Chia, Kee Seng; Kabisch, Maria; Torres, Diana; Jakubowska, Anna; Lubinski, Jan; Sangrajrang, Suleeporn; Brennan, Paul; Slager, Susan; Yannoukakos, Drakoulis; Shen, Chen-Yang; Hou, Ming-Feng; Swerdlow, Anthony; Orr, Nick; Simard, Jacques; Hall, Per; Pharoah, Paul D. P.

    2016-01-01

    The Cancer Genetic Markers of Susceptibility genome-wide association study (GWAS) originally identified a single nucleotide polymorphism (SNP) rs11249433 at 1p11.2 associated with breast cancer risk. To fine-map this locus, we genotyped 92 SNPs in a 900kb region (120,505,799–121,481,132) flanking rs11249433 in 45,276 breast cancer cases and 48,998 controls of European, Asian and African ancestry from 50 studies in the Breast Cancer Association Consortium. Genotyping was done using iCOGS, a custom-built array. Due to the complicated nature of the region on chr1p11.2: 120,300,000–120,505,798, that lies near the centromere and contains seven duplicated genomic segments, we restricted analyses to 429 SNPs excluding the duplicated regions (42 genotyped and 387 imputed). Per-allelic associations with breast cancer risk were estimated using logistic regression models adjusting for study and ancestry-specific principal components. The strongest association observed was with the original identified index SNP rs11249433 (minor allele frequency (MAF) 0.402; per-allele odds ratio (OR) = 1.10, 95% confidence interval (CI) 1.08–1.13, P = 1.49 x 10-21). The association for rs11249433 was limited to ER-positive breast cancers (test for heterogeneity P≤8.41 x 10-5). Additional analyses by other tumor characteristics showed stronger associations with moderately/well differentiated tumors and tumors of lobular histology. Although no significant eQTL associations were observed, in silico analyses showed that rs11249433 was located in a region that is likely a weak enhancer/promoter. Fine-mapping analysis of the 1p11.2 breast cancer susceptibility locus confirms this region to be limited to risk to cancers that are ER-positive. PMID:27556229

  2. Evidence for a susceptibility locus for manic-depressive disorder in Xq26

    Energy Technology Data Exchange (ETDEWEB)

    Pekkarinen, P.; Bredbacka, P.E.; Terwilliger, J. [National Public Health Institute, Helsinki (Finland)] [and others

    1994-09-01

    Manic-depression (MD) is a severe psychiatric disorder affecting 1% of the population. Several linkage studies have provided evidence for a susceptibility locus for MD in chromosome Xq27-28. However, validity of these findings have remained unclear for several reasons: linkage has been suggested to two distinct chromosomal regions (F9 and CB-G6PD) separated by 30 cM, linkage has been found in only few of the pedigrees analyzed and ascertainment bias have probably been introduced when using classical markers like CB. The aim of our study was to analyze several markers expanding both of these regions in one extended Finnish pedigree with 13 affected individuals (bipolar or schizoaffective disorder) and without male-to-male transmission. Together 27 polymorphic X chromosomal markers were studied, 22 of them in Xq25-q28. Linkage analyses were carried out using a dominant model, 0.005 disease gene frequency, age-dependent penetrance with a maximum penetrance of 0.80 and low phenocopy rate. Two-point linkage analyses resulted in clearly negative lod scores (<-2) to almost all markers outside the chromosomal region of Xq26. Three markers DXS458, GABRA3 and G6PD, gave uninformative lod scores but respective chromosomal areas could be excluded by other markers in the vicinity. Opposite to this, several markers on Xq26 resulted in positive lod scores. A maximum lod score of 3.4 was obtained with the marker AFM205wd2 at {theta}=0.0. This marker is located about 7 cM centromeric to F9. When all published linkage data on Xq26-q28 was reanalyzed no evidence for locus heterogeneity emerged suggesting a more general significance of this DNA region in the predisposition to manic-depressive disorder.

  3. A Locus in Drosophila sechellia Affecting Tolerance of a Host Plant Toxin

    Science.gov (United States)

    Hungate, Eric A.; Earley, Eric J.; Boussy, Ian A.; Turissini, David A.; Ting, Chau-Ti; Moran, Jennifer R.; Wu, Mao-Lien; Wu, Chung-I; Jones, Corbin D.

    2013-01-01

    Many insects feed on only one or a few types of host. These host specialists often evolve a preference for chemical cues emanating from their host and develop mechanisms for circumventing their host’s defenses. Adaptations like these are central to evolutionary biology, yet our understanding of their genetics remains incomplete. Drosophila sechellia, an emerging model for the genetics of host specialization, is an island endemic that has adapted to chemical toxins present in the fruit of its host plant, Morinda citrifolia. Its sibling species, D. simulans, and many other Drosophila species do not tolerate these toxins and avoid the fruit. Earlier work found a region with a strong effect on tolerance to the major toxin, octanoic acid, on chromosome arm 3R. Using a novel assay, we narrowed this region to a small span near the centromere containing 18 genes, including three odorant binding proteins. It has been hypothesized that the evolution of host specialization is facilitated by genetic linkage between alleles contributing to host preference and alleles contributing to host usage, such as tolerance to secondary compounds. We tested this hypothesis by measuring the effect of this tolerance locus on host preference behavior. Our data were inconsistent with the linkage hypothesis, as flies bearing this tolerance region showed no increase in preference for media containing M. citrifolia toxins, which D. sechellia prefers. Thus, in contrast to some models for host preference, preference and tolerance are not tightly linked at this locus nor is increased tolerance per se sufficient to change preference. Our data are consistent with the previously proposed model that the evolution of D. sechellia as a M. citrifolia specialist occurred through a stepwise loss of aversion and gain of tolerance to M. citrifolia’s toxins. PMID:24037270

  4. Fine-Mapping of the 1p11.2 Breast Cancer Susceptibility Locus.

    Directory of Open Access Journals (Sweden)

    Hisani N Horne

    Full Text Available The Cancer Genetic Markers of Susceptibility genome-wide association study (GWAS originally identified a single nucleotide polymorphism (SNP rs11249433 at 1p11.2 associated with breast cancer risk. To fine-map this locus, we genotyped 92 SNPs in a 900kb region (120,505,799-121,481,132 flanking rs11249433 in 45,276 breast cancer cases and 48,998 controls of European, Asian and African ancestry from 50 studies in the Breast Cancer Association Consortium. Genotyping was done using iCOGS, a custom-built array. Due to the complicated nature of the region on chr1p11.2: 120,300,000-120,505,798, that lies near the centromere and contains seven duplicated genomic segments, we restricted analyses to 429 SNPs excluding the duplicated regions (42 genotyped and 387 imputed. Per-allelic associations with breast cancer risk were estimated using logistic regression models adjusting for study and ancestry-specific principal components. The strongest association observed was with the original identified index SNP rs11249433 (minor allele frequency (MAF 0.402; per-allele odds ratio (OR = 1.10, 95% confidence interval (CI 1.08-1.13, P = 1.49 x 10-21. The association for rs11249433 was limited to ER-positive breast cancers (test for heterogeneity P≤8.41 x 10-5. Additional analyses by other tumor characteristics showed stronger associations with moderately/well differentiated tumors and tumors of lobular histology. Although no significant eQTL associations were observed, in silico analyses showed that rs11249433 was located in a region that is likely a weak enhancer/promoter. Fine-mapping analysis of the 1p11.2 breast cancer susceptibility locus confirms this region to be limited to risk to cancers that are ER-positive.

  5. Fine-Mapping of the 1p11.2 Breast Cancer Susceptibility Locus.

    Science.gov (United States)

    Horne, Hisani N; Chung, Charles C; Zhang, Han; Yu, Kai; Prokunina-Olsson, Ludmila; Michailidou, Kyriaki; Bolla, Manjeet K; Wang, Qin; Dennis, Joe; Hopper, John L; Southey, Melissa C; Schmidt, Marjanka K; Broeks, Annegien; Muir, Kenneth; Lophatananon, Artitaya; Fasching, Peter A; Beckmann, Matthias W; Fletcher, Olivia; Johnson, Nichola; Sawyer, Elinor J; Tomlinson, Ian; Burwinkel, Barbara; Marme, Frederik; Guénel, Pascal; Truong, Thérèse; Bojesen, Stig E; Flyger, Henrik; Benitez, Javier; González-Neira, Anna; Anton-Culver, Hoda; Neuhausen, Susan L; Brenner, Hermann; Arndt, Volker; Meindl, Alfons; Schmutzler, Rita K; Brauch, Hiltrud; Hamann, Ute; Nevanlinna, Heli; Khan, Sofia; Matsuo, Keitaro; Iwata, Hiroji; Dörk, Thilo; Bogdanova, Natalia V; Lindblom, Annika; Margolin, Sara; Mannermaa, Arto; Kosma, Veli-Matti; Chenevix-Trench, Georgia; Wu, Anna H; Ven den Berg, David; Smeets, Ann; Zhao, Hui; Chang-Claude, Jenny; Rudolph, Anja; Radice, Paolo; Barile, Monica; Couch, Fergus J; Vachon, Celine; Giles, Graham G; Milne, Roger L; Haiman, Christopher A; Marchand, Loic Le; Goldberg, Mark S; Teo, Soo H; Taib, Nur A M; Kristensen, Vessela; Borresen-Dale, Anne-Lise; Zheng, Wei; Shrubsole, Martha; Winqvist, Robert; Jukkola-Vuorinen, Arja; Andrulis, Irene L; Knight, Julia A; Devilee, Peter; Seynaeve, Caroline; García-Closas, Montserrat; Czene, Kamila; Darabi, Hatef; Hollestelle, Antoinette; Martens, John W M; Li, Jingmei; Lu, Wei; Shu, Xiao-Ou; Cox, Angela; Cross, Simon S; Blot, William; Cai, Qiuyin; Shah, Mitul; Luccarini, Craig; Baynes, Caroline; Harrington, Patricia; Kang, Daehee; Choi, Ji-Yeob; Hartman, Mikael; Chia, Kee Seng; Kabisch, Maria; Torres, Diana; Jakubowska, Anna; Lubinski, Jan; Sangrajrang, Suleeporn; Brennan, Paul; Slager, Susan; Yannoukakos, Drakoulis; Shen, Chen-Yang; Hou, Ming-Feng; Swerdlow, Anthony; Orr, Nick; Simard, Jacques; Hall, Per; Pharoah, Paul D P; Easton, Douglas F; Chanock, Stephen J; Dunning, Alison M; Figueroa, Jonine D

    2016-01-01

    The Cancer Genetic Markers of Susceptibility genome-wide association study (GWAS) originally identified a single nucleotide polymorphism (SNP) rs11249433 at 1p11.2 associated with breast cancer risk. To fine-map this locus, we genotyped 92 SNPs in a 900kb region (120,505,799-121,481,132) flanking rs11249433 in 45,276 breast cancer cases and 48,998 controls of European, Asian and African ancestry from 50 studies in the Breast Cancer Association Consortium. Genotyping was done using iCOGS, a custom-built array. Due to the complicated nature of the region on chr1p11.2: 120,300,000-120,505,798, that lies near the centromere and contains seven duplicated genomic segments, we restricted analyses to 429 SNPs excluding the duplicated regions (42 genotyped and 387 imputed). Per-allelic associations with breast cancer risk were estimated using logistic regression models adjusting for study and ancestry-specific principal components. The strongest association observed was with the original identified index SNP rs11249433 (minor allele frequency (MAF) 0.402; per-allele odds ratio (OR) = 1.10, 95% confidence interval (CI) 1.08-1.13, P = 1.49 x 10-21). The association for rs11249433 was limited to ER-positive breast cancers (test for heterogeneity P≤8.41 x 10-5). Additional analyses by other tumor characteristics showed stronger associations with moderately/well differentiated tumors and tumors of lobular histology. Although no significant eQTL associations were observed, in silico analyses showed that rs11249433 was located in a region that is likely a weak enhancer/promoter. Fine-mapping analysis of the 1p11.2 breast cancer susceptibility locus confirms this region to be limited to risk to cancers that are ER-positive.

  6. The effect of paclitaxel alone and in combination with cycloheximide on the frequency of premature centromere division in vitro

    Directory of Open Access Journals (Sweden)

    Bajić V.

    2010-01-01

    Full Text Available Premature centromere division (PCD can be viewed as a manifestation of chromosome instability. In order to evaluate the ability of Paclitaxel (Ptx and Cycloheximide (Cy to induce PCD we used a cytokinesis block micronucleus assay (CBMN, fluorescent in situ hybridization (FISH, and the chromosome aberration (CA assay in human peripheral blood lymphocytes. Results showed that Ptx can induce PCD alone or in combination with Cy. These findings call us to pay more attention to PCD as a parameter of genotoxicity in the pre-clinical research of mono and/or combinational therapies for cancer treatment.

  7. Locus of control and decision to abort.

    Science.gov (United States)

    Dixon, P N; Strano, D A; Willingham, W

    1984-04-01

    The relationship of locus of control to deciding on an abortion was investigated by administering Rotter's Locus of Control Scale to 118 women immediately prior to abortion and 2 weeks and 3 months following abortion. Subjects' scores were compared across the 3 time periods, and the abortion group's pretest scores were compared with those of a nonpregnant control, group. As hypothesized, the aborting group scored significantly more internal than the general population but no differences in locus of control were found across the 3 time period. The length of delay in deciding to abort an unwanted pregnancy following confirmation was also assessed. Women seeking 1st trimester abortions were divided into internal and external groups on the Rotter Scale and the lengths of delay were compared. The hypothesis that external scores would delay the decision longer than internal ones was confirmed. The results confirm characteristics of the locus of control construct and add information about personality characteristics of women undergoing abortion.

  8. A Revised Measure of Locus of Control

    Science.gov (United States)

    Clifford, Margaret M.

    1976-01-01

    A revised measure of locus of control for children and a summary of its descriptive statistics is presented. The nature of the instrument is discussed in light of Weiner's two-dimensional attribution table. (Author/MS)

  9. Maintaining (Locus of) Control? Assessing the Impact of Locus of Control on Education Decisions and Wages

    OpenAIRE

    Piatek, Rémi; Pinger, Pia

    2010-01-01

    This paper demonstrates that locus of control, i.e. whether individuals believe that reinforcement in life comes from their own actions instead of being determined by luck or destiny, is an important predictor of the decision to obtain higher education. Furthermore, the authors find that premarket locus of control, defined as locus of control measured at the time of schooling - before the individual enters the labor market - does not significantly affect later wages after controlling for educ...

  10. Prognostic significance and therapeutic implications of centromere protein F expression in human nasopharyngeal carcinoma

    Directory of Open Access Journals (Sweden)

    Cao Jing-Yan

    2010-09-01

    Full Text Available Abstract Background Our recent cDNA microarray data showed that centromere protein F (CENP-F is significantly upregulated in primary cultured nasopharyngeal carcinoma (NPC tumor cells compared with normal nasopharyngeal epithelial cells. The goal of this study was to further investigate the levels of CENP-F expression in NPC cell lines and tissues to clarify the clinical significance of CENP-F expression in NPC as well as the potential therapeutic implications of CENP-F expression. Methods Real-time RT-PCR and western blotting were used to examine CENP-F expression levels in normal primary nasopharyngeal epithelial cells (NPEC, immortalized nasopharyngeal epithelial cells and NPC cell lines. Levels of CENP-F mRNA were determined by real-time RT-PCR in 23 freshly frozen nasopharyngeal biopsy tissues, and CENP-F protein levels were detected by immunohistochemistry in paraffin sections of 202 archival NPC tissues. Statistical analyses were applied to test for prognostic associations. The cytotoxicities of CENP-F potential target chemicals, zoledronic acid (ZOL and FTI-277 alone, or in combination with cisplatin, in NPC cells were determined by the MTT assay. Results The levels of CENP-F mRNA and protein were higher in NPC cell lines than in normal and immortalized NPECs. CENP-F mRNA level was upregulated in nasopharyngeal carcinoma biopsy tissues compared with noncancerous tissues. By immunohistochemical analysis, CENP-F was highly expressed in 98 (48.5% of 202 NPC tissues. Statistical analysis showed that high expression of CENP-F was positively correlated with T classification (P P P P = 0.012 inversely correlated with the overall survival time in NPC patients. Multivariate analysis showed that CENP-F expression was an independent prognostic indicator for the survival of the patient. Moreover, we found that ZOL or FTI-277 could significantly enhance the chemotherapeutic sensitivity of NPC cell lines (HONE1 and 6-10B with high CENP-F expression to

  11. Narrowing the position of the Treacher Collins syndrome locus to a small interval between three new microsatellite markers at 5q32-33. 1

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, M.J.; Dixon, J. (Univ. of Manchester (United Kingdom)); Houseal, T.; Klinger, K.; Landes, G.M. (Integrated Genetics, Inc., Framingham, MA (United States)); Bhatt, M.; Ward, D.C. (Yale Univ. School of Medicine, New Haven (United States))

    1993-05-01

    Treacher Collins syndrome (TCOF1) is an autosomal dominant disorder of craniofacial development, the features of which include conductive hearing loss and cleft palate. The TCOF1 locus has been localized to chromosome 5q32-33.2. In the present study the authors have used the combined techniques of genetic linkage analysis and fluorescence in situ hybridization (FISH) to more accurately define the TCOF1 critical region. Cosmids IG90 and SPARC, which map to distal 5q, encompass two and one hypervariable microsatellite markers, respectively. The heterozygosity values of these three markers range from .72 to .81. Twenty-two unrelated TCOF1 families have been analyzed for linkage to these markers. There is strong evidence demonstrating linkage to all three markers, the strongest support for positive linkage being provided by haplotyping those markers at the locus encompassed by the cosmid IG90 (Z[sub max]= 19.65; 0 = .010). FISH to metaphase chromosomes and interphase nuclei established that IG90 lies centromeric to SPARC. This information combined with the data generated by genetic linkage analysis demonstrated that the TCOF1 locus is closely flanked proximally by IG90 and distally by SPARC. 30 refs., 2 figs., 4 tabs.

  12. Culture, gender and locus of control

    DEFF Research Database (Denmark)

    Ottsen, Christina Lundsgaard; Johannessen, Kim Berg; Berntsen, Dorthe

    The current study is a cross-cultural comparison between the Middle East and Scandinavia. Two societies that offer a unique opportunity to examine gender differences in personal goals and how goals are affected by locus of control.......The current study is a cross-cultural comparison between the Middle East and Scandinavia. Two societies that offer a unique opportunity to examine gender differences in personal goals and how goals are affected by locus of control....

  13. A recombination outside the BB deletion refines the location of the X-linked retinitis pigmentosa locus RP3

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, R.; Bingham, E.; Forsythe, P.; McHenry, C. [Univ. of Michigan, Ann Arbor, MI (United States)] [and others

    1996-07-01

    Genetic loci for X-linked retinitis pigmentosa (XLRP) have been mapped between Xp11.22 and Xp22.13 (RP2, RP3, RP6, and RP15). The RP3 gene, which is responsible for the predominant form of XLRP in most Caucasian populations, has been localized to Xp21.1 by linkage analysis and the map positions of chromosomal deletions associated with the disease. Previous linkage studies have suggested that RP3 is flanked by the markers DXS1110 (distal) and OTC (proximal). Patient BB was though to have RP because of a lesion at the RP3 locus, in addition to chronic granulomatous disease, Duchenne muscular dystrophy (DMD), mild mental retardation, and the McLeod phenotype. This patient carried a deletion extending {approximately}3 Mb from DMD in Xp21.3 to Xp21.1, with the proximal breakpoint located {approximately}40 kb centromeric to DXS1110. The RP3 gene, therefore, is believed to reside between DXS1110 and the proximal breakpoint of the BB deletion. In order to refine the location of RP3 and to ascertain patients with RP3, we have been analyzing several XLRP families for linkage to Xp markers. Linkage analysis in an American family of 27 individuals demonstrates segregation of XLRP with markers in Xp21.1, consistent with the RP3 subtype. One affected male shows a recombination event proximal to DXS1110. Additional markers within the DXS1110-OTC interval show that the crossover is between two novel polymorphic markers, DXS8349 and M6, both of which are present in BB DNA and lie centromeric to the proximal breakpoint. This recombination places the XLRP mutation in this family outside the BB deletion and redefines the location of RP3. 22 refs., 3 figs., 2 tabs.

  14. Fluorescence In Situ Hybridization (FISH)-Based Karyotyping Reveals Rapid Evolution of Centromeric and Subtelomeric Repeats in Common Bean (Phaseolus vulgaris) and Relatives.

    Science.gov (United States)

    Iwata-Otsubo, Aiko; Radke, Brittany; Findley, Seth; Abernathy, Brian; Vallejos, C Eduardo; Jackson, Scott A

    2016-04-07

    Fluorescence in situ hybridization (FISH)-based karyotyping is a powerful cytogenetics tool to study chromosome organization, behavior, and chromosome evolution. Here, we developed a FISH-based karyotyping system using a probe mixture comprised of centromeric and subtelomeric satellite repeats, 5S rDNA, and chromosome-specific BAC clones in common bean, which enables one to unambiguously distinguish all 11 chromosome pairs. Furthermore, we applied the karyotyping system to several wild relatives and landraces of common bean from two distinct gene pools, as well as other related Phaseolus species, to investigate repeat evolution in the genus Phaseolus Comparison of karyotype maps within common bean indicates that chromosomal distribution of the centromeric and subtelomeric satellite repeats is stable, whereas the copy number of the repeats was variable, indicating rapid amplification/reduction of the repeats in specific genomic regions. In Phaseolus species that diverged approximately 2-4 million yr ago, copy numbers of centromeric repeats were largely reduced or diverged, and chromosomal distributions have changed, suggesting rapid evolution of centromeric repeats. We also detected variation in the distribution pattern of subtelomeric repeats in Phaseolus species. The FISH-based karyotyping system revealed that satellite repeats are actively and rapidly evolving, forming genomic features unique to individual common bean accessions and Phaseolus species. Copyright © 2016 Iwata-Otsubo et al.

  15. Fluorescence In Situ Hybridization (FISH-Based Karyotyping Reveals Rapid Evolution of Centromeric and Subtelomeric Repeats in Common Bean (Phaseolus vulgaris and Relatives

    Directory of Open Access Journals (Sweden)

    Aiko Iwata-Otsubo

    2016-04-01

    Full Text Available Fluorescence in situ hybridization (FISH-based karyotyping is a powerful cytogenetics tool to study chromosome organization, behavior, and chromosome evolution. Here, we developed a FISH-based karyotyping system using a probe mixture comprised of centromeric and subtelomeric satellite repeats, 5S rDNA, and chromosome-specific BAC clones in common bean, which enables one to unambiguously distinguish all 11 chromosome pairs. Furthermore, we applied the karyotyping system to several wild relatives and landraces of common bean from two distinct gene pools, as well as other related Phaseolus species, to investigate repeat evolution in the genus Phaseolus. Comparison of karyotype maps within common bean indicates that chromosomal distribution of the centromeric and subtelomeric satellite repeats is stable, whereas the copy number of the repeats was variable, indicating rapid amplification/reduction of the repeats in specific genomic regions. In Phaseolus species that diverged approximately 2–4 million yr ago, copy numbers of centromeric repeats were largely reduced or diverged, and chromosomal distributions have changed, suggesting rapid evolution of centromeric repeats. We also detected variation in the distribution pattern of subtelomeric repeats in Phaseolus species. The FISH-based karyotyping system revealed that satellite repeats are actively and rapidly evolving, forming genomic features unique to individual common bean accessions and Phaseolus species.

  16. Quantification, by solid-phase minisequencing, of the telomeric and centromeric copies of the survival motor neuron gene in families with spinal muscular atrophy

    DEFF Research Database (Denmark)

    Schwartz, M; Sørensen, N; Hansen, F J

    1997-01-01

    In an analysis of 30 families affected by spinal muscular atrophy (SMA) we have used the solid-phase minisequencing method to determine the ratio between the number of telomeric and centromeric copies of the survival motor neuron gene (SMN and cBCD541 respectively) on normal and SMA chromosomes...

  17. Structure, mitotic and meiotic behaviour, and stability of centromere-like elements devoid of chromosome arms in the fly Megaselia scalaris (Phoridae).

    Science.gov (United States)

    Wolf, K W; Mertl, H G; Traut, W

    1991-11-01

    Minute elements detected in Megaselia scalaris (Phoridae, Diptera) lack chromosome arms but carry centromeres and possess kinetochore microtubules in mitosis as well as in meiosis. These centromere-like elements (CLEs) were present in two geographically independent strains of the fly. This indicates that their origin is not a recent event in the karyotype evolution of M. scalaris and that they are rather stable constituents of the karyotype. Most often, two CLEs were found in gonial and somatic mitosis. Spermatocytes contained one CLE. Two individuals examined deviated from this rule in that a metaphase spermatogonium showed three and an anaphase spermatogonium eight CLEs. These animals are believed to have been aneuploid relative to the CLEs. An analysis of spermatogonial division revealed that the CLEs behave like the centromeres of the regular chromosomes but seem to separate precociously, since they were closer to the spindle poles in late anaphase cells. Whereas the size of the CLEs was not significantly different between mitotic cells and secondary spermatocytes, the CLEs in primary spermatocytes were larger in volume by a factor of about 4.5 than those in mitosis and meiosis II. The additional material is interpreted as a glue that holds two CLEs together. This, in turn, is a prerequisite for orderly segregation. The function of the CLEs is not known. They are considered as B chromosomes reduced to the minimum required for segregation, the centromere.

  18. Juvenile myoclonic epilepsy locus in chromosome 6p21.2-p11: Linkage to convulsions and electroencephalography trait

    Energy Technology Data Exchange (ETDEWEB)

    Liu, A.W.; Delgado-Escueta, A.V.; Serratosa, J.M. [and others

    1995-08-01

    Despite affecting 4 million Americans and 100-200 million persons worldwide, the precise molecular mechanisms of human epilepsies remain unknown. Juvenile myoclonic epilepsy (JME) is the most frequent and, hence, most important form of hereditary grand mal epilepsy. In this epilepsy, electroencephalographic (EEG) 15-30 Hz multispikes produce myoclonic and tonic-clonic convulsions beginning at 8-20 years of age. Moreover, EEG 3.5-6 Hz multispike wave complexes appear in clinically asymptomatic family members. We first studied 38 members of a four-generation LA-Belize family with classical JME but with no pyknoleptic absences. Five living members had JME; four clinically asymptomatic members had EEG multispike wave complexes. Pairwise analysis tightly linked microsatellites centromeric to HLA, namely D6S272 (peak lod score [Z{sub max}]=3.564-3.560 at male-female recombination [{theta}{sub m=f}]=0-0.001) and D6S257 (Z{sub max}=3.672-3.6667 at {theta}{sub m=f}=0-0.001), spanning 7 cM, to convulsive seizures and EEG multispike wave complexes. A recombination between D6S276 and D6S273 in one affected member placed the JME locus within or below HLA. Pairwise, multipoint, and recombination analyses in this large family independently proved that a JME gene is located in chromsome 6p, centromeric to HLA. We next screened, with the same chromosome 6p21.2-p11 short tandem-repeat polymorphic markers, seven multiplex pedigrees with classic JME. When lod scores for small multiplex families are added to lod scores of the LA-Belize pedigree, Z{sub max} values for D6S294 and D6S257 are >7 ({theta}{sub m=f}=0.000). Our results prove that in chromosome 6p21.2-p11 an epilepsy locus exists whose phenotype consists of classic JME with convulsions and/or EEG rapid multispike wave complexes. 31 refs., 6 figs., 4 tabs.

  19. Kartenorientierte Isolierung des Rar1 Locus

    OpenAIRE

    Lahaye, Thomas

    1999-01-01

    The Mla12 allele of the barley-Mla locus confers resistance to powdery mildew isolates expressing the matching avirulence gene avrMla12. The Rar1 (Required for Mla12-specified resistance) locus has been found to be part of the Mla12-governed signal transduction pathway. Previous analysis has demonstrated that rar1-mutant alleles abolish not only Mla12 but also other R gene specificities. To elucidate the molecular mechanisms of R-gene mediated plant defence Rar1 was isolated by map-based clon...

  20. Locus of control in relation to flow

    Directory of Open Access Journals (Sweden)

    Celeste M Taylor

    2006-03-01

    Full Text Available The principal objective of the study was to examine the relationship between locus of control and optimal experience (flow in carrying out work and/or study activities. Two questionnaires measuring the aforementioned constructs were administered to a group of first and second-year Human Resource Management students (n=168 between the ages of 16 and 30. The results suggest that more frequent experience of flow is positively correlated with Autonomy and Internal Locus of Control. Limitations, lines of future research, implications and further contributions are discussed.

  1. Locus of control in children of divorce.

    Science.gov (United States)

    Kalter, N; Alpern, D; Spence, R; Plunkett, J W

    1984-08-01

    Scores on the Nowicki-Strickland Locus of Control Scale for Children (N-SLOCSC) were compared for third and fifth grade boys and girls from intact versus maritally disrupted family backgrounds. Significant main effects for each independent variable revealed that fifth graders more than third, boys more than girls, and the marital disruption more than the intact group, exhibited higher internality in their locus of control scores. These findings strongly suggest that experiencing a parental divorce in childhood has a significant influence on generalized perceptions of personal control and effectance, perceptions which may ultimately mediate both short- and long-term outcomes in children's post-divorce adjustment.

  2. Schizosaccharomyces pombe centromere protein Mis19 links Mis16 and Mis18 to recruit CENP-A through interacting with NMD factors and the SWI/SNF complex.

    Science.gov (United States)

    Hayashi, Takeshi; Ebe, Masahiro; Nagao, Koji; Kokubu, Aya; Sajiki, Kenichi; Yanagida, Mitsuhiro

    2014-07-01

    CENP-A is a centromere-specific variant of histone H3 that is required for accurate chromosome segregation. The fission yeast Schizosaccharomyces pombe and mammalian Mis16 and Mis18 form a complex essential for CENP-A recruitment to centromeres. It is unclear, however, how the Mis16-Mis18 complex achieves this function. Here, we identified, by mass spectrometry, novel fission yeast centromere proteins Mis19 and Mis20 that directly interact with Mis16 and Mis18. Like Mis18, Mis19 and Mis20 are localized at the centromeres during interphase, but not in mitosis. Inactivation of Mis19 in a newly isolated temperature-sensitive mutant resulted in CENP-A delocalization and massive chromosome missegregation, whereas Mis20 was dispensable for proper chromosome segregation. Mis19 might be a bridge component for Mis16 and Mis18. We isolated extragenic suppressor mutants for temperature-sensitive mis18 and mis19 mutants and used whole-genome sequencing to determine the mutated sites. We identified two groups of loss-of-function suppressor mutations in non-sense-mediated mRNA decay factors (upf2 and ebs1), and in SWI/SNF chromatin-remodeling components (snf5, snf22 and sol1). Our results suggest that the Mis16-Mis18-Mis19-Mis20 CENP-A-recruiting complex, which is functional in the G1-S phase, may be counteracted by the SWI/SNF chromatin-remodeling complex and non-sense-mediated mRNA decay, which may prevent CENP-A deposition at the centromere. © 2014 The Authors Genes to Cells © 2014 by the Molecular Biology Society of Japan and Wiley Publishing Asia Pty Ltd.

  3. Expressed Centromere Specific Histone 3 (CENH3 Variants in Cultivated Triploid and Wild Diploid Bananas (Musa spp.

    Directory of Open Access Journals (Sweden)

    Kariuki S. Muiruri

    2017-06-01

    Full Text Available Centromeres are specified by a centromere specific histone 3 (CENH3 protein, which exists in a complex environment, interacting with conserved proteins and rapidly evolving satellite DNA sequences. The interactions may become more challenging if multiple CENH3 versions are introduced into the zygote as this can affect post-zygotic mitosis and ultimately sexual reproduction. Here, we characterize CENH3 variant transcripts expressed in cultivated triploid and wild diploid progenitor bananas. We describe both splice- and allelic-[Single Nucleotide Polymorphisms (SNP] variants and their effects on the predicted secondary structures of protein. Expressed CENH3 transcripts from six banana genotypes were characterized and clustered into three groups (MusaCENH-1A, MusaCENH-1B, and MusaCENH-2 based on similarity. The CENH3 groups differed with SNPs as well as presence of indels resulting from retained and/or skipped exons. The CENH3 transcripts from different banana genotypes were spliced in either 7/6, 5/4 or 6/5 exons/introns. The 7/6 and the 5/4 exon/intron structures were found in both diploids and triploids, however, 7/6 was most predominant. The 6/5 exon/introns structure was a result of failure of the 7/6 to splice correctly. The various transcripts obtained were predicted to encode highly variable N-terminal tails and a relatively conserved C-terminal histone fold domain (HFD. The SNPs were predicted in some cases to affect the secondary structure of protein by lengthening or shorting the affected domains. Sequencing of banana CENH3 transcripts predicts SNP variations that affect amino acid sequences and alternatively spliced transcripts. Most of these changes affect the N-terminal tail of CENH3.

  4. Escape from Mitotic Arrest: An Unexpected Connection Between Microtubule Dynamics and Epigenetic Regulation of Centromeric Chromatin in Schizosaccharomyces pombe.

    Science.gov (United States)

    George, Anuja A; Walworth, Nancy C

    2015-12-01

    Accurate chromosome segregation is necessary to ensure genomic integrity. Segregation depends on the proper functioning of the centromere, kinetochore, and mitotic spindle microtubules and is monitored by the spindle assembly checkpoint (SAC). In the fission yeast Schizosaccharomyces pombe, defects in Dis1, a microtubule-associated protein that influences microtubule dynamics, lead to mitotic arrest as a result of an active SAC and consequent failure to grow at low temperature. In a mutant dis1 background (dis1-288), loss of function of Msc1, a fission yeast homolog of the KDM5 family of proteins, suppresses the growth defect and promotes normal mitosis. Genetic analysis implicates a histone deacetylase (HDAC)-linked pathway in suppression because HDAC mutants clr6-1, clr3∆, and sir2∆, though not hos2∆, also promote normal mitosis in the dis1-288 mutant. Suppression of the dis phenotype through loss of msc1 function requires the spindle checkpoint protein Mad2 and is limited by the presence of the heterochromatin-associated HP1 protein homolog Swi6. We speculate that alterations in histone acetylation promote a centromeric chromatin environment that compensates for compromised dis1 function by allowing for successful kinetochore-microtubule interactions that can satisfy the SAC. In cells arrested in mitosis by mutation of dis1, loss of function of epigenetic determinants such as Msc1 or specific HDACs can promote cell survival. Because the KDM5 family of proteins has been implicated in human cancers, an appreciation of the potential role of this family of proteins in chromosome segregation is warranted. Copyright © 2015 by the Genetics Society of America.

  5. Phylogenetic Analysis of the SNORD116 Locus

    Directory of Open Access Journals (Sweden)

    Matthew A. Kocher

    2017-11-01

    Full Text Available The SNORD116 small nucleolar RNA locus (SNORD116@ is contained within the long noncoding RNA host gene SNHG14 on human chromosome 15q11-q13. The SNORD116 locus is a cluster of 28 or more small nucleolar (sno RNAs; C/D box (SNORDs. Individual RNAs within the cluster are tandem, highly similar sequences, referred to as SNORD116-1, SNORD116-2, etc., with the entire set referred to as SNORD116@. There are also related SNORD116 loci on other chromosomes, and these additional loci are conserved among primates. Inherited chromosomal 15q11-q13 deletions, encompassing the SNORD116@ locus, are causative for the paternally-inherited/maternally-imprinted genetic condition, Prader–Willi syndrome (PWS. Using in silico tools, along with molecular-based and sequenced-based confirmation, phylogenetic analysis of the SNORD116@ locus was performed. The consensus sequence for the SNORD116@ snoRNAs from various species was determined both for all the SNORD116 snoRNAs, as well as those grouped using sequence and location according to a human grouping convention. The implications of these findings are put in perspective for studying SNORD116 in patients with inherited Prader–Willi syndrome, as well as model organisms.

  6. Aspirations, Attributions, and Locus of Control.

    Science.gov (United States)

    Samuel, William; McNall, Sidne J.

    Self-evaluation is thought to play a major role in personality and motivation. Preliminary experience with success or failure, levels of aspiration, attributions for performance, and locus of control may all be interrelated factors in human motivation. After receiving success, failure, or no feedback on a concept formation task, subjects (N=90)…

  7. Locus of Equity and Brand Extension

    NARCIS (Netherlands)

    S.M.J. van Osselaer (Stijn); J.W. Alba (Joseph)

    2003-01-01

    textabstractPrevailing wisdom assumes that brand equity increases when a brand touts its desirable attributes. We report conditions under which the use of attribute information to promote a product can shift the locus of equity from brand to attribute, thereby reducing the attractiveness of

  8. The Impact of Locus of Control on Language Achievement

    Science.gov (United States)

    Nodoushan, Mohammad Ali Salmani

    2012-01-01

    This study hypothesized that students' loci of control affected their language achievement. 198 (N = 198) EFL students took the Rotter's (1966) locus of control test and were classified as locus-internal (ni = 78), and locus-external (ne = 120). They then took their ordinary courses and at the end of the semester, they were given their exams.…

  9. Fine mapping and chromosome walking towards the Ror1 locus in barley (Hordeum vulgare L.).

    Science.gov (United States)

    Acevedo-Garcia, Johanna; Collins, Nicholas C; Ahmadinejad, Nahal; Ma, Lu; Houben, Andreas; Bednarek, Pawel; Benjdia, Mariam; Freialdenhoven, Andreas; Altmüller, Janine; Nürnberg, Peter; Reinhardt, Richard; Schulze-Lefert, Paul; Panstruga, Ralph

    2013-12-01

    The Ror1 gene was fine-mapped to the pericentric region of barley chromosome 1HL. Recessively inherited loss-of-function alleles of the barley (Hordeum vulgare) Mildew resistance locus o (Mlo) gene confer durable broad-spectrum disease resistance against the obligate biotrophic fungal powdery mildew pathogen Blumeria graminis f.sp. hordei. Previous genetic analyses revealed two barley genes, Ror1 and Ror2, that are Required for mlo-specified resistance and basal defence. While Ror2 was cloned and shown to encode a t-SNARE protein (syntaxin), the molecular nature or Ror1 remained elusive. Ror1 was previously mapped to the centromeric region of the long arm of barley chromosome 1H. Here, we narrowed the barley Ror1 interval to 0.18 cM and initiated a chromosome walk using barley yeast artificial chromosome (YAC) clones, next-generation DNA sequencing and fluorescence in situ hybridization. Two non-overlapping YAC contigs containing Ror1 flanking genes were identified. Despite a high degree of synteny observed between barley and the sequenced genomes of the grasses rice (Oryza sativa), Brachypodium distachyon and Sorghum bicolor across the wider chromosomal area, the genes in the YAC contigs showed extensive interspecific rearrangements in orientation and order. Consequently, the position of a Ror1 homolog in these species could not be precisely predicted, nor was a barley gene co-segregating with Ror1 identified. These factors have prevented the molecular identification of the Ror1 gene for the time being.

  10. Genetic linkage studies in familial partial epilepsy: Exclusion of the human chromosome regions syntenic to the El-1 mouse locus

    Energy Technology Data Exchange (ETDEWEB)

    Lopes-Cendes, I. [Montreal General Hospital (Canada); Mulley, J.C. [Alelaide Children`s Hospital (Canada); Andermann, E. [Montreal Neurological Institute and Hospital, Quebec (Canada)] [and others

    1994-09-01

    Recently, six families with a familial form of partial epilepsy were described. All pedigrees showed autosomal dominant inheritance with incomplete penetrance. Affected individuals present with predominantly nocturnal seizures with frontal lobe semiology. In 1959, a genetic mouse model for partial epilepsy, the El mouse, was reported. In the El mouse, a major seizure susceptibility gene, El-1, segregates in an autosomal dominant fashion and has been localized to a region distal to the centromere of mouse chromosome 9. Comparative genetic maps between man and mouse have been used for prediction of localization of several human disease genes. Because the region of mouse chromosome 9 that is the most likely to contain the El-1 locus is syntenic to regions on human chromosomes 3q21-p22, 3q21-q23.3, 6q12 and 15q24, we adopted the candidate gene approach as an initial linkage strategy. Twenty-two polymorphic microsatellite markers covering these regions were used for genotyping individuals in the three larger families ascertained, two of which are Australian and one French-Canadian. Negative two-point lod scores were obtained separately for each family. The analysis of all three families combined significantly excludes the candidate regions on chromosomes 3, 6 and 15.

  11. Novel ZBTB24 Mutation Associated with Immunodeficiency, Centromere Instability, and Facial Anomalies Type-2 Syndrome Identified in a Patient with Very Early Onset Inflammatory Bowel Disease.

    Science.gov (United States)

    Conrad, Máire A; Dawany, Noor; Sullivan, Kathleen E; Devoto, Marcella; Kelsen, Judith R

    2017-12-01

    Very early onset inflammatory bowel disease, diagnosed in children ≤5 years old, can be the initial presentation of some primary immunodeficiencies. In this study, we describe a 17-month-old boy with recurrent infections, growth failure, facial anomalies, and inflammatory bowel disease. Immune evaluation, whole-exome sequencing, karyotyping, and methylation array were performed to evaluate the child's constellation of symptoms and examination findings. Whole-exome sequencing revealed that the child was homozygous for a novel variant in ZBTB24, the gene associated with immunodeficiency, centromere instability, and facial anomalies type-2 syndrome. This describes the first case of inflammatory bowel disease associated with immunodeficiency, centromere instability, and facial anomalies type-2 syndrome in a child with a novel disease-causing mutation in ZBTB24 found on whole-exome sequencing.

  12. Preferential recruitment of the maternal centromere-specific histone H3 (CENH3) in oat (Avena sativa L.) × pearl millet (Pennisetum glaucum L.) hybrid embryos.

    Science.gov (United States)

    Ishii, Takayoshi; Sunamura, Naohiro; Matsumoto, Ayaka; Eltayeb, Amin Elsadig; Tsujimoto, Hisashi

    2015-12-01

    Chromosome elimination occurs frequently in interspecific hybrids between distantly related species in Poaceae. However, chromosomes from both parents behave stably in a hybrid of female oat (Avena sativa L.) pollinated by pearl millet (Pennisetum glaucum L.). To analyze the chromosome behavior in this hybrid, we cloned the centromere-specific histone H3 (CENH3) genes of oat and pearl millet and produced a pearl millet-specific anti-CENH3 antibody. Application of this antibody together with a grass species common anti-CENH3 antibody revealed the dynamic CENH3 composition of the hybrid cells before and after fertilization. Despite co-expression of CENH3 genes encoded by oat and pearl millet, only an oat-type CENH3 was incorporated into the centromeres of both species in the hybrid embryo. Oat CENH3 enables a functional centromere in pearl millet chromosomes in an oat genetic background. Comparison of CENH3 genes among Poaceae species that show chromosome elimination in interspecific hybrids revealed that the loop 1 regions of oat and pearl millet CENH3 exhibit exceptionally high similarity.

  13. Novel sequencing strategy for repetitive DNA in a Drosophila BAC clone reveals that the centromeric region of the Y chromosome evolved from a telomere.

    Science.gov (United States)

    Méndez-Lago, María; Wild, Jadwiga; Whitehead, Siobhan L; Tracey, Alan; de Pablos, Beatriz; Rogers, Jane; Szybalski, Waclaw; Villasante, Alfredo

    2009-04-01

    The centromeric and telomeric heterochromatin of eukaryotic chromosomes is mainly composed of middle-repetitive elements, such as transposable elements and tandemly repeated DNA sequences. Because of this repetitive nature, Whole Genome Shotgun Projects have failed in sequencing these regions. We describe a novel kind of transposon-based approach for sequencing highly repetitive DNA sequences in BAC clones. The key to this strategy relies on physical mapping the precise position of the transposon insertion, which enables the correct assembly of the repeated DNA. We have applied this strategy to a clone from the centromeric region of the Y chromosome of Drosophila melanogaster. The analysis of the complete sequence of this clone has allowed us to prove that this centromeric region evolved from a telomere, possibly after a pericentric inversion of an ancestral telocentric chromosome. Our results confirm that the use of transposon-mediated sequencing, including positional mapping information, improves current finishing strategies. The strategy we describe could be a universal approach to resolving the heterochromatic regions of eukaryotic genomes.

  14. A stable acentric marker chromosome derived from distal 8p: Reactivation of a latent ancient centromere at 8p23.1?

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, H.; Wakui, K.; Ogawa, K. [Saitama Children`s Medical Ctr., Iwatsuki (Japan)] [and others

    1994-09-01

    Centromere is considered to be an essential chromosomal component for faithful segregation, and acentric chromosomes are unstable and lost through cell divisions. We report a novel marker chromosome that was acentric but stable through cell divisions. The patient was a 2-year-old girl with mental retardation, patent ductus arteriosus and mild dysmorphic features. G-banded chromosome analysis revealed an additional small marker chromosome in all 100 cells examined. Using the targeted chromosome-band painting method, the marker was found to originate from the distal region of 8p, and subsequent two color FISH analysis with cosmid probes around the region revealed the marker was a rearranged chromosome interpreted as 8pter{r_arrow}p23.1{r_arrow}8pter. No centromeric region was involved in the marker. By FISH, no {alpha}-satellite sequence was detected on the marker, while telomere sequence was detected at each end. Antikinetochore immunostaining using a serum from a patient with CREST syndrome showed a pair of signals on the marker, which indicated that a functional kinetochore was present on the marker, presumably at 8p23.1-corresponding region. The patient may provide evidence that an ancient centromere sequence exists at 8p23.1 and was reactivated through the chromosome rearrangement in the patient.

  15. Spermatid nucleus of Megaselia scalaris Loew (Insecta, Diptera, Phoridae): a study using anti-histone antibodies, scanning electron microscopy, and a centromere-specific oligonucleotide.

    Science.gov (United States)

    Wolf, K W; Jeppesen, P; Mitchell, A

    1993-07-01

    The structure of elongated spermatid nuclei was examined in the fly Megaselia scalaris using indirect immunofluorescence with anti-histone antibodies, scanning electron microscopy, and in situ hybridization with a centromere-specific oligonucleotide. The immunofluorescence experiments showed that, in keeping with the situation in most animals, histones are hyperacetylated prior to their displacement from the nucleus in the course of spermiogenesis. Scanning electron microscopy revealed that grooves run parallel to the long axis of the spermatid nuclei. The chromatin is segmented into blocks lateral to the grooves. This finding most probably indicates that the chromatin is not yet maximally condensed at this stage. The retarded chromatin condensation may be correlated with the export of somatic histones from the nucleus. The location of the centromeres could not be identified using scanning electron microscopy, but in situ hybridization showed that a centromere-specific oligonucleotide mapped to the central or close to the central areas within the spermatid nucleus. Possibly, the chromosomes are extended and arranged parallel to the long axis of the spermatid nucleus.

  16. Condensin HEAT subunits required for DNA repair, kinetochore/centromere function and ploidy maintenance in fission yeast.

    Directory of Open Access Journals (Sweden)

    Xingya Xu

    Full Text Available Condensin, a central player in eukaryotic chromosomal dynamics, contains five evolutionarily-conserved subunits. Two SMC (structural maintenance of chromosomes subunits contain ATPase, hinge, and coiled-coil domains. One non-SMC subunit is similar to bacterial kleisin, and two other non-SMC subunits contain HEAT (similar to armadillo repeats. Here we report isolation and characterization of 21 fission yeast (Schizosaccharomyces pombe mutants for three non-SMC subunits, created using error-prone mutagenesis that resulted in single-amino acid substitutions. Beside condensation, segregation, and DNA repair defects, similar to those observed in previously isolated SMC and cnd2 mutants, novel phenotypes were observed for mutants of HEAT-repeats containing Cnd1 and Cnd3 subunits. cnd3-L269P is hypersensitive to the microtubule poison, thiabendazole, revealing defects in kinetochore/centromere and spindle assembly checkpoints. Three cnd1 and three cnd3 mutants increased cell size and doubled DNA content, thereby eliminating the haploid state. Five of these mutations reside in helix B of HEAT repeats. Two non-SMC condensin subunits, Cnd1 and Cnd3, are thus implicated in ploidy maintenance.

  17. Centromere protein W interacts with beta-transducin repeat-containing protein 1 and modulates its subcellular localization.

    Science.gov (United States)

    Cheon, Yeongmi; Jeon, Seyeong; Lee, Soojin

    2016-12-01

    Beta-transducin repeat-containing protein 1 (β-TrCP1) is a substrate-recognition module of SCF(β-Tr)(CP)(1) ubiquitin ligases and its subcellular distribution is known to be critical for target specificity. Heterogeneous nuclear ribonucleoprotein (hnRNP) U, an abundant nuclear protein, is known to be a unique regulator of β-TrCP1 shuttling between the cytoplasm and the nucleus. In this study, we report that centromere protein W (CENP-W), which is frequently overexpressed in a variety of human cancers, may also contribute to β-TrCP1 shuttling. Although hnRNP U and CENP-W can interact with β-TrCP1 and transport it independently, these proteins do not compete for β-TrCP1 binding, but rather cooperate to form a stable shuttling complex. Intriguingly, we found that overexpression of CENP-W leads to accumulation of β-TrCP1 in the nucleus. Thus, we propose that CENP-W may function as a booster of β-TrCP1 nuclear import to increase the oncogenicity of β-TrCP1. © 2016 Federation of European Biochemical Societies.

  18. Genetic and physical mapping of the Treacher Collins syndrome locus with respect to loci in the chromosome 5q3 region

    Energy Technology Data Exchange (ETDEWEB)

    Jabs, E.W.; Li, Xiang; Coss, C.; Taylor, E. (Johns Hopkins School of Medicine, Baltimore, MD (United States)); Lovett, M. (Univ. of Texas Southwestern Medical Center, San Antonio, TX (United States)); Yamaoka, L.H.; Speer, M.C. (Duke Univ. Medical Center, Durham, NC (United States)); Cadle, R.; Hall, B. (Univ. of Kentucky, Lexington, KY (United States)); Brown, K. (Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY (United States)) (and others)

    1993-10-01

    Treacher Collins syndrome is an autosomal dominant, craniofacial developmental disorder, and its locus (TCOF1) has been mapped to chromosome 5q3. To refine the location of the gene within this region, linkage analysis was performed among the TCOF1 locus and 12 loci (IL9, FGFA, GRL, D5S207, D5S210, D5S376, CSF1R, SPARC, D5S119, D5S209, D5S527, FGFR4) in 13 Treacher Collins syndrome families. The highest maximum lod score was obtained between loci TCOF1 and D5S210 (Z = 10.52; [theta] = 0.02 [+-] 0.07). The best order, IL9-GRL-D5S207/D5S210-CSF1R-SPARC-D5S119, and genetic distances among these loci were determined in the 40 CEPH families by multipoint linkage analysis. YAC clones were used to establish the order of loci, centromere-5[prime]GRL3[prime]-D5S207-D5S210-D5S376-CSF1R-SPARC-D5S119-telomere. By combining known physical mapping data with ours, the order of chromosome 5q3 markers is centomere-IL9-FGFA-5[prime]GRL3[prime]-D5s207-D5S210-D5S376-CSF1R-SPARC-D5S119-D5S209-FGFR4-telomere. Based on this order, haplotype analysis suggests that the TCOF1 locus resides distal CSF1R and proximal to SPARC within a region less than 1 Mb in size. 29 refs., 2 figs., 2 tabs.

  19. Familial hyperinsulinism maps to chromosome 11p14-15.1, 30 cM centromeric to the insulin gene.

    Science.gov (United States)

    Glaser, B; Chiu, K C; Anker, R; Nestorowicz, A; Landau, H; Ben-Bassat, H; Shlomai, Z; Kaiser, N; Thornton, P S; Stanley, C A

    1994-06-01

    Familial hyperinsulinism (HI) is the most common cause of persistent neonatal hyperinsulinaemic hypoglycemia. Linkage analysis in 15 families (12 Ashkenazi Jewish, 2 consanguineous Arab, 1 non-Jewish Caucasian) mapped HI to chromosome 11p14-15.1 (lod score = 9.5, theta = 0 at D11S921). Recombinants localized the disease locus to the 6.6 cM interval between D11S926 and D11S928. In Jewish families, association (p = 0.003) with specific D11S921/D11S419 haplotypes suggested a founder effect. This locus, which is important for normal glucose-regulated insulin secretion, represents a candidate gene for studies of other diseases of beta-cell dysfunction including non-insulin-dependent diabetes mellitus (NIDDM).

  20. Locus of control and online learning

    Directory of Open Access Journals (Sweden)

    Suretha Esterhuysen

    2004-10-01

    Full Text Available The integration of online learning in university courses is considered to be both inevitable and necessary. Thus there is an increasing need to raise awareness among educators and course designers about the critical issues impacting on online learning. The aim of this study, therefore, was to assess the differences between two groups of first-year Business Sciences learners (online and conventional learners in terms of biographic and demographic characteristics and locus of control. The study population consisted of 586 first-year learners of whom 185 completed the Locus of Control Inventory (LCI. The results show that the two groups of learners do not differ statistically significantly from each other with respect to locus of control. The findings and their implications are also discussed. Opsomming Die integrasie van aanlyn-leer in universiteitskursusse word beskou as sowel onafwendbaar as noodsaaklik. Daar is dus ’n toenemende behoefte om bewustheid onder opvoedkundiges en kursusontwerpers te kweek oor die kritiese aspekte wat ’n impak op aanlyn-leer het (Morgan, 1996. Daarom was die doel van hierdie ondersoek om die verskille tussen twee groepe eerstejaarleerders in Bestuurs- en Ekonomiese Wetenskap (aanlyn en konvensionele leerders te bepaal ten opsigte van biografiese en demografiese eienskappe en lokus van beheer. Die populasie het bestaan uit 586 eerstejaarleerders waarvan 185 die Lokus van Beheer Vraelys voltooi het. Die resultate toon dat die twee groepe leerders nie statisties beduidend van mekaar verskil het met betrekking tot lokus van beheer nie. Die bevindinge en implikasies word ook bespreek.

  1. Cut Locus Construction using Deformable Simplicial Complexes

    DEFF Research Database (Denmark)

    Misztal, Marek Krzysztof; Bærentzen, Jakob Andreas; Anton, François

    2011-01-01

    In this paper we present a method for appproximating cut loci for a given point p on Riemannian 2D manifolds, closely related to the notion of Voronoi diagrams. Our method finds the cut locus by advecting a front of points equally distant from p along the geodesics originating at p and finding th...... the domain to have disk topology. We test our method for tori of revolution and compare our results to the benchmark ones from [2]. The method, however, is generic and can be easily adapted to construct cut loci for other manifolds of genera other than 1....

  2. An empirical assessment of the construct "work locus of control"

    Directory of Open Access Journals (Sweden)

    Allan Maram

    1998-06-01

    Full Text Available This study is concerned with the domain specificity of the locus of control construct within the workplace. The research investigated whether Specter's (1988 work locus of control scale, a work centred conceptualisation of Rotter's (1966 locus of control measure/ demonstrated evidence of criterion - related validity. This was done by assessing its relationship to leader-member exchange and organisational commitment. The results indicated that work locus of control correlated with both leader-member exchange and organisational commitment and that leadermember exchange acted as a mediator of the relationship between work locus of control and organisational commitment. This is consistent with results from a similar study undertaken by Kinicki & Vecchio (1994 who employed Rotter's (1966 general locus of control measure. The current research demonstrated stronger relationship than Kinicki & Vecchio's (1994 study, which suggests that Specter's (1988 domain specific scale may predict work behaviour more precisely than Rotter's (1966 more general measure.

  3. Locus of boundary crisis: expect infinitely many gaps.

    Science.gov (United States)

    Osinga, Hinke M

    2006-09-01

    Boundary crisis is a mechanism for destroying a chaotic attractor when one parameter is varied. In a two-parameter setting the locus of the boundary crisis is associated with curves of homoclinic or heteroclinic bifurcations of periodic saddle points. It is known that this locus has nondifferentiable points. We show here that the locus of boundary crisis is far more complicated than previously reported. It actually contains infinitely many gaps, corresponding to regions (of positive measure) where attractors exist.

  4. Impact of locus of control on health message effectiveness.

    Science.gov (United States)

    Kong, Ying; Shen, Fuyuan

    2011-10-01

    This article examined how individuals' locus of control might moderate the effect of health message frames. An experiment was conducted whereby participants read either individual- or social-responsibility message frames after their locus of control was primed. Results indicated that messages presented in individual-responsibility frames were more persuasive when people were primed with internal locus of control, whereas social-responsibility framed appeals were more persuasive when people were primed with external locus of control. These results were found for individuals in both high and low cognitive load conditions. Theoretical and practical implications of the findings are discussed.

  5. Beyond the locus of spectrally pure colors

    Science.gov (United States)

    Fairchild, Mark D.

    2008-01-01

    The spectrum locus of a CIE chromaticity diagram defines the boundary within which all physically realizable color stimuli must fall. While that is a physical and mathematical reality that cannot be violated, it is possible to create colors that appear as if they were produced by physically impossible stimuli. This can be accomplished through careful control of the viewing conditions and states of adaptation. This paper highlights the importance of considering color appearance issues in the design of displays and specification of color gamuts and illustrates how the perceived color gamut can be manipulated significantly through the relationship between white-point and primary luminance levels without changing the chromaticity gamut of a display system. Using a color appearance model, such as CIECAM02, display color gamuts can be specified in perceptual terms such as lightness, chroma, brightness, and colorfulness rather than in strictly physical terms of the stimuli that create these perceptions. Examination of these perceptual gamuts, and their relationships to the viewing conditions, allows demonstration of the possibility of producing display gamuts that appear to reach beyond the locus of pure spectral colors when compared with typical display setups.

  6. Detection and Automated Scoring of Dicentric Chromosomes in Nonstimulated Lymphocyte Prematurely Condensed Chromosomes After Telomere and Centromere Staining

    Energy Technology Data Exchange (ETDEWEB)

    M' kacher, Radhia [Laboratoire de Radiobiologie et Oncologie, Commissariat à l' Energie Atomique, Fontenay-aux-Roses (France); El Maalouf, Elie [Laboratoire de Radiobiologie et Oncologie, Commissariat à l' Energie Atomique, Fontenay-aux-Roses (France); Laboratoire Modélisation Intelligence Processus Systèmes (MIPS)–Groupe TIIM3D, Université de Haute-Alsace, Mulhouse (France); Terzoudi, Georgia [Laboratory of Radiobiology & Biodosimetry, National Center for Scientific Research Demokritos, Athens (Greece); Ricoul, Michelle [Laboratoire de Radiobiologie et Oncologie, Commissariat à l' Energie Atomique, Fontenay-aux-Roses (France); Heidingsfelder, Leonhard [MetaSystems, Altlussheim (Germany); Karachristou, Ionna [Laboratory of Radiobiology & Biodosimetry, National Center for Scientific Research Demokritos, Athens (Greece); Laplagne, Eric [Pole Concept, Paris (France); Hempel, William M. [Laboratoire de Radiobiologie et Oncologie, Commissariat à l' Energie Atomique, Fontenay-aux-Roses (France); Colicchio, Bruno; Dieterlen, Alain [Laboratoire Modélisation Intelligence Processus Systèmes (MIPS)–Groupe TIIM3D, Université de Haute-Alsace, Mulhouse (France); Pantelias, Gabriel [Laboratory of Radiobiology & Biodosimetry, National Center for Scientific Research Demokritos, Athens (Greece); Sabatier, Laure, E-mail: laure.sabatier@cea.fr [Laboratoire de Radiobiologie et Oncologie, Commissariat à l' Energie Atomique, Fontenay-aux-Roses (France)

    2015-03-01

    Purpose: To combine telomere and centromere (TC) staining of premature chromosome condensation (PCC) fusions to identify dicentrics, centric rings, and acentric chromosomes, making possible the realization of a dose–response curve and automation of the process. Methods and Materials: Blood samples from healthy donors were exposed to {sup 60}Co irradiation at varying doses up to 8 Gy, followed by a repair period of 8 hours. Premature chromosome condensation fusions were carried out, and TC staining using peptide nucleic acid probes was performed. Chromosomal aberration (CA) scoring was carried out manually and automatically using PCC-TCScore software, developed in our laboratory. Results: We successfully optimized the hybridization conditions and image capture parameters, to increase the sensitivity and effectiveness of CA scoring. Dicentrics, centric rings, and acentric chromosomes were rapidly and accurately detected, leading to a linear-quadratic dose–response curve by manual scoring at up to 8 Gy. Using PCC-TCScore software for automatic scoring, we were able to detect 95% of dicentrics and centric rings. Conclusion: The introduction of TC staining to the PCC fusion technique has made possible the rapid scoring of unstable CAs, including dicentrics, with a level of accuracy and ease not previously possible. This new approach can be used for biological dosimetry in radiation emergency medicine, where the rapid and accurate detection of dicentrics is a high priority using automated scoring. Because there is no culture time, this new approach can also be used for the follow-up of patients treated by genotoxic therapy, creating the possibility to perform the estimation of induced chromosomal aberrations immediately after the blood draw.

  7. Molecular characterization and chromosomal distribution of a species-specific transcribed centromeric satellite repeat from the olive fruit fly, Bactrocera oleae.

    Directory of Open Access Journals (Sweden)

    Konstantina T Tsoumani

    Full Text Available Satellite repetitive sequences that accumulate in the heterochromatin consist a large fraction of a genome and due to their properties are suggested to be implicated in centromere function. Current knowledge of heterochromatic regions of Bactrocera oleae genome, the major pest of the olive tree, is practically nonexistent. In our effort to explore the repetitive DNA portion of B. oleae genome, a novel satellite sequence designated BoR300 was isolated and cloned. The present study describes the genomic organization, abundance and chromosomal distribution of BoR300 which is organized in tandem, forming arrays of 298 bp-long monomers. Sequence analysis showed an AT content of 60.4%, a CENP-B like-motif and a high curvature value based on predictive models. Comparative analysis among randomly selected monomers demonstrated a high degree of sequence homogeneity (88%-97% of BoR300 repeats, which are present at approximately 3,000 copies per haploid genome accounting for about 0.28% of the total genomic DNA, based on two independent qPCR approaches. In addition, expression of the repeat was also confirmed through RT-PCR, by which BoR300 transcripts were detected in both sexes. Fluorescence in situ hybridization (FISH of BoR300 on mitotic metaphases and polytene chromosomes revealed signals to the centromeres of two out of the six chromosomes which indicated a chromosome-specific centromeric localization. Moreover, BoR300 is not conserved in the closely related Bactrocera species tested and it is also absent in other dipterans, but it's rather restricted to the B. oleae genome. This feature of species-specificity attributed to BoR300 satellite makes it a good candidate as an identification probe of the insect among its relatives at early development stages.

  8. The Cell Cycle Timing of Centromeric Chromatin Assembly in Drosophila Meiosis Is Distinct from Mitosis Yet Requires CAL1 and CENP-C

    Science.gov (United States)

    Gorgescu, Walter; Tang, Jonathan; Costes, Sylvain V.; Karpen, Gary H.

    2012-01-01

    CENP-A (CID in flies) is the histone H3 variant essential for centromere specification, kinetochore formation, and chromosome segregation during cell division. Recent studies have elucidated major cell cycle mechanisms and factors critical for CENP-A incorporation in mitosis, predominantly in cultured cells. However, we do not understand the roles, regulation, and cell cycle timing of CENP-A assembly in somatic tissues in multicellular organisms and in meiosis, the specialized cell division cycle that gives rise to haploid gametes. Here we investigate the timing and requirements for CID assembly in mitotic tissues and male and female meiosis in Drosophila melanogaster, using fixed and live imaging combined with genetic approaches. We find that CID assembly initiates at late telophase and continues during G1 phase in somatic tissues in the organism, later than the metaphase assembly observed in cultured cells. Furthermore, CID assembly occurs at two distinct cell cycle phases during male meiosis: prophase of meiosis I and after exit from meiosis II, in spermatids. CID assembly in prophase I is also conserved in female meiosis. Interestingly, we observe a novel decrease in CID levels after the end of meiosis I and before meiosis II, which correlates temporally with changes in kinetochore organization and orientation. We also demonstrate that CID is retained on mature sperm despite the gross chromatin remodeling that occurs during protamine exchange. Finally, we show that the centromere proteins CAL1 and CENP-C are both required for CID assembly in meiosis and normal progression through spermatogenesis. We conclude that the cell cycle timing of CID assembly in meiosis is different from mitosis and that the efficient propagation of CID through meiotic divisions and on sperm is likely to be important for centromere specification in the developing zygote. PMID:23300382

  9. Locus - ASTRA | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data ...URL: ftp://ftp.biosciencedbc.jp/archive/astra/LATEST/astra_locus.zip File size: 887 KB Simple search URL htt...icing type (ex. cassette) About This Database Database Description Download License Update History of This Database Site Policy | Contact Us Locus - ASTRA | LSDB Archive ...

  10. Locus of Control and Its Affect on Achievement.

    Science.gov (United States)

    Tomlinson, Louise M.

    Locus of control is considered a primary factor in the difference between students' high and low achievement. This phenomenon is defined as a polar construct which refers to the degree to which individuals view their successes and failures as either contingent upon their own behaviors (internal locus of control) or independent of them (external…

  11. Metacognition: As a Predictor of One's Academic Locus of Control

    Science.gov (United States)

    Arslan, Serhat; Akin, Ahmet

    2014-01-01

    The purpose of this study is to examine the effect of metacognition on one's academic locus of control. The study's sample group consists of 451 university students enrolled in various programs at Sakarya University, Turkey. In this study, the Metacognitive Awareness Inventory and the Academic Locus of Control Scale were used. The correlations and…

  12. Changing Locus of Control: Steelworkers Adjusting to Forced Unemployment

    Science.gov (United States)

    Legerski, Elizabeth Miklya; Cornwall, Marie; O'Neil, Brock

    2006-01-01

    Using an abbreviated version of Levenson's (1981) locus of control scale, we examine change over time in the locus of control of displaced steelworkers. The first data collection occurred approximately six months after plant shutdown, the second occurred a year later. Utilizing a multidimensional measurement model, we test the major assumption…

  13. Locus of control and investment in risky assets

    NARCIS (Netherlands)

    Salamanca, N.; de Grip, A.; Fouarge, D.; Montizaan, R.M.

    2013-01-01

    Using representative household panel data, we show that the investment behavior of households is related to the economic locus of control of household heads. A household's internal locus of control in economic issues is positively related to its decision to hold risky assets as well as its share of

  14. Pharmacists as Entrepreneurs or Employees: The Role of Locus of ...

    African Journals Online (AJOL)

    Purpose: To investigate whether locus of control distinguished between pharmacists who chose to become entrepreneurs and those who took up employee roles in pharmaceutical establishments. Methods: The enlarged version of Rotter's I-E scale designed to measure an individual's locus of control was used to survey a ...

  15. A new strategy for estimating two-locus recombination fractions ...

    Indian Academy of Sciences (India)

    Linkage analysis is now being widely used to map markers on each chromosome in the human genome, to map genetic diseases, and to identify genetic forms of common diseases. Two-locus linkage analysis and multi-locus analysis have been investigated comprehensively, and many computer programs have been ...

  16. Nucleotide variation at the methionine synthase locus in an ...

    African Journals Online (AJOL)

    Nucleotide variation at the methionine synthase (MetE) locus within and among populations of an endangered forest tree Fokienia hodginsii in Vietnam was investigated in the present study. A total of 12 populations were sampled across Vietnam. The length of the sequenced locus varied from 1567 to 1559 bp. A total of 42 ...

  17. Health Beliefs and Locus of Control as Predictors of Cancer ...

    African Journals Online (AJOL)

    OR= 0.35, p < 0.05), internal locus of control (OR = 1.43, p < 0.05) and health risks behaviour (OR= 0.42, p < 0.05) all significantly predicted cervical cancer screening behaviour of women. Keywords: Health beliefs, Health locus of control, cancer ...

  18. Pharmacists as Entrepreneurs or Employees: The Role of Locus of ...

    African Journals Online (AJOL)

    Patrick Erah

    Methods: The enlarged version of Rotter's I-E scale designed to measure an individual's locus of ..... Research Instrument: The instrument used to .... qualified pharmacists who chose to become entrepreneurs and those who chose employee status in organisations. Those who showed more locus of control internality are ...

  19. Is this Red Spot the Blue Spot (locus ceruleum)?

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Won Sick; Lee, Yu Kyung; Lee, Min Kyung; Hwang, Kyung Hoon [Gachon University Gil Hospital, Incheon (Korea, Republic of)

    2010-06-15

    The authors report brain images of 18F-FDG-PET in a case of schizophrenia. The images showed strikingly increased bilateral uptake in the locus ceruleum. The locus ceruleum is called the blue spot and known to be a center of the norepinephrinergic system.

  20. The Role of Locus of Control in Leader Influence Behavior.

    Science.gov (United States)

    Johnson, Avis L.; And Others

    1984-01-01

    Investigated whether leader's (N=89) locus of control moderated the relationship between perceived leader influence behaviors and certain subordinate (N=245) outcome variables. The results showed that locus of control did significantly moderate the effect of supervisor influence on productivity and subordinate satisfaction with supervision. (JAC)

  1. The relationship between internal and external locus of control of ...

    African Journals Online (AJOL)

    The method of this study was descriptive and correlational type. The statistic population in this study included parents of children, male and ... Research samples were assessed by using questionnaires Rutter locus of control and aggression. The results of the analysis showed that there is relationship between internal locus ...

  2. Personality and Locus of Control among School Children

    Science.gov (United States)

    Pandya, Archana A.; Jogsan, Yogesh A.

    2013-01-01

    The main purpose of this investigation is to find out the sex differences in personality traits and locus of control among school children. A total 60 children (30 boys and 30 girls) were taken as a sample. The research tool for personality, children personality questionnaire was used, which was made by Cattell and Porter. Locus of control was…

  3. Turkish population data on the short tandem repeat locus TPOX

    DEFF Research Database (Denmark)

    Vural, B; Poda, M; Atlioglu, E

    1998-01-01

    Allele and genotype frequencies were determined for the STR (short tandem repeat) locus TPOX in a random Turkish population sample of 200 individuals.......Allele and genotype frequencies were determined for the STR (short tandem repeat) locus TPOX in a random Turkish population sample of 200 individuals....

  4. DNA deformability changes of single base pair mutants within CDE binding sites in S. Cerevisiae centromere DNA correlate with measured chromosomal loss rates and CDE binding site symmetries

    Directory of Open Access Journals (Sweden)

    Marx Kenneth A

    2006-03-01

    Full Text Available Abstract Background The centromeres in yeast (S. cerevisiae are organized by short DNA sequences (125 bp on each chromosome consisting of 2 conserved elements: CDEI and CDEIII spaced by a CDEII region. CDEI and CDEIII are critical sequence specific protein binding sites necessary for correct centromere formation and following assembly with proteins, are positioned near each other on a specialized nucleosome. Hegemann et al. BioEssays 1993, 15: 451–460 reported single base DNA mutants within the critical CDEI and CDEIII binding sites on the centromere of chromosome 6 and quantitated centromere loss of function, which they measured as loss rates for the different chromosome 6 mutants during cell division. Olson et al. Proc Natl Acad Sci USA 1998, 95: 11163–11168 reported the use of protein-DNA crystallography data to produce a DNA dinucleotide protein deformability energetic scale (PD-scale that describes local DNA deformability by sequence specific binding proteins. We have used the PD-scale to investigate the DNA sequence dependence of the yeast chromosome 6 mutants' loss rate data. Each single base mutant changes 2 PD-scale values at that changed base position relative to the wild type. In this study, we have utilized these mutants to demonstrate a correlation between the change in DNA deformability of the CDEI and CDEIII core sites and the overall experimentally measured chromosome loss rates of the chromosome 6 mutants. Results In the CDE I and CDEIII core binding regions an increase in the magnitude of change in deformability of chromosome 6 single base mutants with respect to the wild type correlates to an increase in the measured chromosome loss rate. These correlations were found to be significant relative to 105 Monte Carlo randomizations of the dinucleotide PD-scale applied to the same calculation. A net loss of deformability also tends to increase the loss rate. Binding site position specific, 4 data-point correlations were also

  5. Escala de Locus de controle ELCO/TELEBRÁS Scale of Locus of control - ELCO

    Directory of Open Access Journals (Sweden)

    Luiz Pasquali

    1998-01-01

    Full Text Available Com base na teoria de Rotter e Escala de Levenson foi elaborada uma escala de Locus de Controle Organizacional (ELCO, composta por 28 itens. A escala foi validada com uma amostra de 350 empregados do Sistema Telebrás. Verificou-se a presença dos 2 fatores previstos na teoria, a saber: internalidade e externalidade, aparecendo a escala de externalidade, com 18 itens, bem estruturada (alfa = 0.81 e a de internalidade, com 10 itens, deixando a desejar no que se refere à consistência interna (alfa = 0.66. Com os dados desta pesquisa foi feita também análise do Locus de Controle desses mesmos empregados. A constatação mais saliente foi a de que o nível de internalidade caiu com o aumento do nível escolar e o aumento da experiência profissional desses mesmos empregados. Estes resultados surpreendentes foram interpretados em termos da situação típica da empresa, que está passando por um período de transição, a saber: a passagem da condição de empresa estatal para empresa privada, o que seria motivo da perda de confiança dos empregados na própria competência, particularmente por parte daqueles com maior competência intelectual e maior experiência profissional. Fez-se igualmente reparos na qualidade psicométrica da escala e da própria teoria do Locus de controle, no sentido de que esta precisa ser melhor axiomatizada para possibilitar a elaboração de escalas mais precisas para a medida dos construtos que propõe.A scale with 28 items, the Organizational Locus of Control (ELCO, was built based on Rotter’s theory and Levenson’s scale. ELCO was validated on a sample of 350 employees of Telebrás, a governmental firm in Brazil. As foreseen from the theory, a principal-axis factoring showed the presence of the expected two factors, namely internal and external locus of control. The external locus of control factor, composed of 18 items, showed good internal consistency (alpha =.81 whereas the internal factor, with 10 items

  6. Locus of Control Orientation: Parents, Peers, and Place.

    Science.gov (United States)

    Ahlin, Eileen M; Lobo Antunes, Maria João

    2015-09-01

    An internal locus of control contributes to positive youth outcomes such as a general well-being and academic success, while also serving as a protective factor against exposure to community violence and reducing negative behaviors like violence. Despite these benefits, very little is known about antecedents of an internal locus of control orientation. Without an understanding of what factors contribute to the development of an internal locus of control, it is not clear how to best encourage its formation. This study uses data from the Project on Human Development in Chicago Neighborhoods to examine whether various mesosystem variables (family management strategies, peer interactions, neighborhood context, and individual-level characteristics) are associated with an internal locus of control orientation among 1,076 youth ages 9-19 living in 78 Chicago neighborhoods. Study participants were Hispanic (46 %), African American (34 %), and White (15 %), and 50 % were female. The findings suggest that, while most levels of the mesosystem influence locus of control orientation, family management strategies are more prominent determinants of an internal locus of control than peers, neighborhood context, or individual characteristics. Parental supervision over the time a youth spends at home and family socioeconomic status are consistent predictors of an internal locus of control, while harsh discipline is associated with an external locus of control. The discussion examines the import of various parenting techniques in shaping an internal locus of control and considers future avenues for research to further unpack how antecedents of locus of control can vary across youth.

  7. Health Locus of Control尺度開発の歴史(社会科学編)

    OpenAIRE

    吉田, 由美; Yumi, Yoshida; 千葉県立衛生短期大学(歯科保存学); Chiba College of Health Science

    1994-01-01

    This article describes the origins history of Health Locus of Control scales. First, Rotter's social learing theory, which is the theoretical background of the Health Locus of Control construct, is outlined. The scale and research trends of Locus of Control concept, and those of Health Locus of Control concept which are based on Locus of Control, are then reviewed. Finally, Health Locus of Control is discussed with regard to the implications for health education.

  8. Tandem repeat sequences evolutionarily related to SVA-type retrotransposons are expanded in the centromere region of the western hoolock gibbon, a small ape.

    Science.gov (United States)

    Hara, Toru; Hirai, Yuriko; Jahan, Israt; Hirai, Hirohisa; Koga, Akihiko

    2012-12-01

    Hoolock hoolock (the western hoolock gibbon) is a species of the family Hylobatidae (small apes), which constitutes the superfamily Hominoidea (hominoids) together with Hominidae (great apes and human). Here, we report that centromeres or their vicinities in this gibbon species contain tandem repeat sequences that consist of 35-50-bp repeat units, and exhibit a sequence similarity with the variable number of tandem repeat (VNTR) region of the SVA, LAVA and PVA transposons. SVA is a composite retrotransposon thought to have been formed by fusion of three solo elements in the common ancestor of hominoids. LAVA and PVA are recently identified retrotransposons that have the same basic structure as SVA. Thus, the large-scale tandem repeats in the centromere region may have been derived from one or more of SVA-type transposons, including the three mentioned above and other yet unknown elements, or the repeat sequences could have served as a source for such elements. Amplification of VNTR-related sequences in another gibbon species, Hoolock leuconedys (eastern hoolock gibbon), has recently been reported, but it is yet to be examined whether the large-scale tandem repeats observed in the two species originated from a single event that occurred in their common ancestor. The repeat sequences in the western hoolock gibbon are mostly 40 kb or more in length, are present in 28 of the 38 chromosomes of the somatic cells, and are homozygous for chromosomal presence/absence.

  9. Lack of independent prognostic and predictive value of centromere 17 copy number changes in breast cancer patients with known HER2 and TOP2A status

    DEFF Research Database (Denmark)

    Nielsen, Kirsten Vang; Ejlertsen, Bent; Møller, Susanne

    2011-01-01

    The clinical benefit of anthracyclines has been connected to HER2 status, TOP2A status and centromere 17 copy numbers (CEN-17). Data from a clinical trial randomizing patients to anthracyclines was used to assess whether the number of CEN-17 in breast cancers may predict incremental responsiveness...... were applied to data on 767 patients with known HER2 and TOP2A status randomized to anthracyclines in the DBCG 89D trial. CEN-17 ploidy levels were in cut sections from the 767 breast cancer patients established as: Haploid: ≤1.25 (10%), diploid: 1.26-2.09 (60%), triploid: 2.10-2.93 (21%), tetraploid...... hybridization (FISH) with centromere 17 (CEN-17) and TOP2A was performed on 120 normal breast specimens. The diploid CEN-17 copy number was reduced from the expected two signals in whole nuclei to an average of 1.68 signals per nucleus in cut sections of normal breast. Ploidy levels determined in normal breast...

  10. Transcriptional Response of Human Neurospheres to Helper-Dependent CAV-2 Vectors Involves the Modulation of DNA Damage Response, Microtubule and Centromere Gene Groups.

    Directory of Open Access Journals (Sweden)

    Stefania Piersanti

    Full Text Available Brain gene transfer using viral vectors will likely become a therapeutic option for several disorders. Helper-dependent (HD canine adenovirus type 2 vectors (CAV-2 are well suited for this goal. These vectors are poorly immunogenic, efficiently transduce neurons, are retrogradely transported to afferent structures in the brain and lead to long-term transgene expression. CAV-2 vectors are being exploited to unravel behavior, cognition, neural networks, axonal transport and therapy for orphan diseases. With the goal of better understanding and characterizing HD-CAV-2 for brain therapy, we analyzed the transcriptomic modulation induced by HD-CAV-2 in human differentiated neurospheres derived from midbrain progenitors. This 3D model system mimics several aspects of the dynamic nature of human brain. We found that differentiated neurospheres are readily transduced by HD-CAV-2 and that transduction generates two main transcriptional responses: a DNA damage response and alteration of centromeric and microtubule probes. Future investigations on the biochemistry of processes highlighted by probe modulations will help defining the implication of HD-CAV-2 and CAR receptor binding in enchaining these functional pathways. We suggest here that the modulation of DNA damage genes is related to viral DNA, while the alteration of centromeric and microtubule probes is possibly enchained by the interaction of the HD-CAV-2 fibre with CAR.

  11. Loss of Centromere Cohesion in Aneuploid Human Oocytes Correlates with Decreased Kinetochore Localization of the Sac Proteins Bub1 and Bubr1.

    Science.gov (United States)

    Lagirand-Cantaloube, Julie; Ciabrini, Cendrine; Charrasse, Sophie; Ferrieres, Alice; Castro, Anna; Anahory, Tal; Lorca, Thierry

    2017-03-13

    In human eggs, aneuploidy increases with age and can result in infertility and genetic diseases. Studies in mouse oocytes suggest that reduced centromere cohesion and spindle assembly checkpoint (SAC) activity could be at the origin of chromosome missegregation. Little is known about these two features in humans. Here, we show that in human eggs, inter-kinetochore distances of bivalent chromosomes strongly increase with age. This results in the formation of univalent chromosomes during metaphase I (MI) and of single chromatids in metaphase II (MII). We also investigated SAC activity by checking the localization of BUB1 and BUBR1. We found that they localize at the kinetochore with a similar temporal timing than in mitotic cells and in a MPS1-dependent manner, suggesting that the SAC signalling pathway is active in human oocytes. Moreover, our data also suggest that this checkpoint is inactivated when centromere cohesion is lost in MI and consequently cannot inhibit premature sister chromatid separation. Finally, we show that the kinetochore localization of BUB1 and BUBR1 decreases with the age of the oocyte donors. This could contribute to oocyte aneuploidy.

  12. Development of a YAC contig covering the minimal region of a CSNB1 locus in Xp11

    Energy Technology Data Exchange (ETDEWEB)

    Boycott, K.M.; Gratton, K.J.; Moore, B.J. [Univ. of Calgary (Canada)] [and others

    1994-09-01

    X-linked congenital stationary night blindness (CSNB1) is an eye disorder that includes impairment of night vision, reduced visual acuity and, in some cases, myopia and congenital nystagmus. Electroretinography reveals a marked reduction of the b-wave in affected individuals suggesting that X-linked CSNB is due to a molecular defect in the bipolar layer of the retina. Based on our studies of a large four generation family with X-linked CSNB, a CSNB1 locus was mapped to a 4-5 cM region at Xp11.23-Xp11.22 bounded telomerically by DXS426 and centromerically by DXS988. Using a panel of radiation and conventional somatic cell hybrids, a detailed map of new and published STSs has been generated for the minimal region of CSNB1. PCR primer pairs for STSs has been generated for the minimal region of CSNB1. PCR primer pairs for twenty-five STSs, including eleven end-clones, were used to isolate YAC clones from CEPH, mega-CEPH, and X chromosome-specific YAC libraries. In total, fifty-two YACs were characterized for STS overlaps and assembled to provide a minimum of 3 Mb of physical coverage in the region between DXS426 and DXS988. Five gaps proximal to SYP are still to be closed. Our physical map suggests the following gene order: Xpter-OTAL1-GF1-DXS1011E-MG81-HUMCRAS2P-SYP-Xcen. STS analysis of the YACs revealed three subregions of the physical map which appear to be particularly susceptible to internal deletions and end-clone analysis demonstrated chimerism in six of seventeen YACs. A physical map of Xp11.23-Xp11.22 will provide a resource for the isolation of candidate genes for the X-linked CSNB gene which maps to this region.

  13. Detecting purely epistatic multi-locus interactions by an omnibus permutation test on ensembles of two-locus analyses

    Directory of Open Access Journals (Sweden)

    Limwongse Chanin

    2009-09-01

    Full Text Available Abstract Background Purely epistatic multi-locus interactions cannot generally be detected via single-locus analysis in case-control studies of complex diseases. Recently, many two-locus and multi-locus analysis techniques have been shown to be promising for the epistasis detection. However, exhaustive multi-locus analysis requires prohibitively large computational efforts when problems involve large-scale or genome-wide data. Furthermore, there is no explicit proof that a combination of multiple two-locus analyses can lead to the correct identification of multi-locus interactions. Results The proposed 2LOmb algorithm performs an omnibus permutation test on ensembles of two-locus analyses. The algorithm consists of four main steps: two-locus analysis, a permutation test, global p-value determination and a progressive search for the best ensemble. 2LOmb is benchmarked against an exhaustive two-locus analysis technique, a set association approach, a correlation-based feature selection (CFS technique and a tuned ReliefF (TuRF technique. The simulation results indicate that 2LOmb produces a low false-positive error. Moreover, 2LOmb has the best performance in terms of an ability to identify all causative single nucleotide polymorphisms (SNPs and a low number of output SNPs in purely epistatic two-, three- and four-locus interaction problems. The interaction models constructed from the 2LOmb outputs via a multifactor dimensionality reduction (MDR method are also included for the confirmation of epistasis detection. 2LOmb is subsequently applied to a type 2 diabetes mellitus (T2D data set, which is obtained as a part of the UK genome-wide genetic epidemiology study by the Wellcome Trust Case Control Consortium (WTCCC. After primarily screening for SNPs that locate within or near 372 candidate genes and exhibit no marginal single-locus effects, the T2D data set is reduced to 7,065 SNPs from 370 genes. The 2LOmb search in the reduced T2D data reveals

  14. Reinforcement of genetic coherence in a two-locus model.

    Science.gov (United States)

    Gregorius, H R; Steiner, W

    2001-01-01

    In order to maintain populations as units of reproduction and thus enable anagenetic evolution, genetic factors must exist which prevent continuing reproductive separation or enhance reproductive contact. This evolutionary principle is called genetic coherence and it marks the often ignored counterpart of cladistic evolution. Possibilities of the evolution of genetic coherence are studied with the help of a two-locus model with two alleles at each locus. The locus at which viability selection takes place is also the one that controls the fusion of gametes. The second locus acts on the first by modifying the control of the fusion probabilities. It thus acts as a mating modifier whereas the first locus plays the role of the object of selection and mating. Genetic coherence is enhanced by modifications which confer higher probabilities of fusion to heterotypic gametic combinations (resulting in heterozygous zygotes) at the object locus. It is shown that mutants at the mating modifier locus, which increase heterotypic fusions but do not lower the homotpyic fusions relative to the resident allele at the object locus, generally replace the resident allele. Since heterozygote advantage at the object locus is a necessary condition for this result to hold true, reinforcement of genetic coherence can be claimed for this case. If the homotypic fusions are lowered, complex situations may arise which may favor or disfavor the mutant depending on initial frequencies and recombination rates. To allow for a generalized analysis including alternative models of genetic coherence as well as the estimation of its degrees in real populations, an operational concept for the measurement of this degree is developed. The resulting index is applied to the interpretation of data from crossing experiments in Alnus species designed to detect incompatibility relations.

  15. Reinforcement of genetic coherence in a two-locus model

    Directory of Open Access Journals (Sweden)

    Steiner Wilfried

    2001-08-01

    Full Text Available Abstract Background In order to maintain populations as units of reproduction and thus enable anagenetic evolution, genetic factors must exist which prevent continuing reproductive separation or enhance reproductive contact. This evolutionary principle is called genetic coherence and it marks the often ignored counterpart of cladistic evolution. Possibilities of the evolution of genetic coherence are studied with the help of a two-locus model with two alleles at each locus. The locus at which viability selection takes place is also the one that controls the fusion of gametes. The second locus acts on the first by modifying the control of the fusion probabilities. It thus acts as a mating modifier whereas the first locus plays the role of the object of selection and mating. Genetic coherence is enhanced by modifications which confer higher probabilities of fusion to heterotypic gametic combinations (resulting in heterozygous zygotes at the object locus. Results It is shown that mutants at the mating modifier locus, which increase heterotypic fusions but do not lower the homotpyic fusions relative to the resident allele at the object locus, generally replace the resident allele. Since heterozygote advantage at the object locus is a necessary condition for this result to hold true, reinforcement of genetic coherence can be claimed for this case. If the homotypic fusions are lowered, complex situations may arise which may favor or disfavor the mutant depending on initial frequencies and recombination rates. To allow for a generalized analysis including alternative models of genetic coherence as well as the estimation of its degrees in real populations, an operational concept for the measurement of this degree is developed. The resulting index is applied to the interpretation of data from crossing experiments in Alnus species designed to detect incompatibility relations.

  16. EL LOCUS DE DISTRIBUCION COMO COROLARIO DEL LOCUS DE CONTROL (THE LOCUS OF DISTRIBUTION AS A COROLLARY TO THE LOCUS OF CONTROL

    Directory of Open Access Journals (Sweden)

    Mayoral Luisa

    2009-08-01

    Full Text Available Resumen: Este es un artículo científico acerca del Locus de Distribución, surgido de un estudio realizado con una población de docentes y alumnos universitarios. Respecto de los primeros, se ha indagado acerca de las atribuciones que se realizaban en torno a las recompensas y sanciones, que ellos distribuían a sus alumnos.Respecto de los segundos, se ha buscado determinar la valoración que estos realizaban de sus profesores, en términos de aquellas atribuciones. Para ello, se utilizaron dos paradigmas clásicamente empleados para verificar la existencia de una norma: el paradigma de la autopresentación (docentes, y el paradigma de los j uicios (alumnos. La cuestión planteada fue determinar si en el caso de los comportamientos distributivos de refuerzos, las causas se atribuían a variables externas -en particular a los receptores de esos refuerzos- y si esas formas de atribución eran conocidas y valoradas o no, por los alumnos. De los resultados, surgió la confirmación de nuestra hipótesis de explicaciones externas en materia de comportamientos distributivos de sanciones en el ámbito de la docencia y la valoración positiva de estas atribuciones por los alumnos.Abstract:This one is a scientific article brings over of the Locus of Distribution, arisen from a study realized with a population of teachers and university pupils. Respect of the first ones, it has been investigated brings over of the attributions that were concerning around the reinforcements which they were distributing to pupils. Respect of the second ones, one has sought to determine the valuation that these realized of the teachers, in terms of those attributions. For it, two paradigms were in use classic used to check the existence of a norm: the paradigm of the auto-presentation (teachers, and the paradigm of the judgments (pupils The raised question was to determine if in case of the distributive behaviours of reinforcements, the reasons were assuming to external

  17. Generators of synchronous activity of the locus coeruleus during development.

    Science.gov (United States)

    Christie, M J

    1997-02-01

    The locus coeruleus is thought to play an important role in the development of the central nervous system through a coordinated release of noradrenaline. The influence of the locus coeruleus on its diverse targets is strongly synchronized by the existence of electrical and chemical coupling between neurones, afferent supply of the nucleus from restricted sources and diffuse innervation of target areas. Extensive coupling between neonatal locus coeruleus neurones produces rhythmic synchronized electrical activity and distributes afferent synaptic activity throughout the entire nucleus. The strength of electrical coupling declines with age but appears to persist to a limited extent in the adult.

  18. Relation of organizational citizenship behavior and locus of control.

    Science.gov (United States)

    Turnipseed, David L; Bacon, Calvin M

    2009-12-01

    The relation of organizational citizenship behavior and locus of control was assessed in a sample of 286 college students (52% men; M age = 24 yr.) who worked an average of 26 hr. per week. Measures were Spector's Work Locus of Control Scale and Podsakoff, et al.'s Organization Citizenship Behavior scale. Hierarchical multiple regressions indicated positive association of scores on work locus of control with scores on each of the four tested dimensions of organizational citizenship, as well as total organizational citizenship behavior.

  19. Relationship among Dimensions of Family Communication Patterns and Locus of

    Directory of Open Access Journals (Sweden)

    Mohammad Hassan Anvari

    2014-05-01

    Full Text Available Background: This study was done to examine the relationship of self-efficacy with dimensions of family communication patterns and locus of control. Materials and Methods: The population of this study was all Isfahan University students in the 2010-2011 academic years. Two hundred seventy nine students from various faculties of the university selected by cluster sampling method. In this descriptive study were used from the revised scale of dimensions of family communication patterns, locus of control questionnaire and general self-efficacy scale. Results: Results showed that the dialogue orientation, locus of control and conformity orientation have a significant correlation with self-efficacy (p<0.01. In addition dialogue orientation, locus of control and conformity orientation predicted 13%, 7%, 2% of selfefficacy, respectively. Conclusion: Dialogue orientation in family is the most important predictor of students' self-efficacy.

  20. Multidimensional profiles of health locus of control in Hispanic Americans.

    Science.gov (United States)

    Champagne, Brian R; Fox, Rina S; Mills, Sarah D; Sadler, Georgia Robins; Malcarne, Vanessa L

    2016-10-01

    Latent profile analysis identified health locus of control profiles among 436 Hispanic Americans who completed the Multidimensional Health Locus of Control scales. Results revealed four profiles: Internally Oriented-Weak, -Moderate, -Strong, and Externally Oriented. The profile groups were compared on sociocultural and demographic characteristics, health beliefs and behaviors, and physical and mental health outcomes. The Internally Oriented-Strong group had less cancer fatalism, religiosity, and equity health attributions, and more alcohol consumption than the other three groups; the Externally Oriented group had stronger equity health attributions and less alcohol consumption. Deriving multidimensional health locus of control profiles through latent profile analysis allows examination of the relationships of health locus of control subtypes to health variables. © The Author(s) 2015.

  1. A new strategy for estimating two-locus recombination fractions ...

    Indian Academy of Sciences (India)

    2011-08-19

    locus recombination fractions under some natural inequality restrictions. J. Genet. 90, 275–282]. Introduction. Linkage analysis is used in both human and other biologi- cal studies. Lathrop et al. (1984) discussed the strategies ...

  2. Locus of Control and Technology Adoption in Developing Country Agriculture

    DEFF Research Database (Denmark)

    Abay, Kibrom Araya; Blalock, Garrick; Berhane, Guush

    2017-01-01

    adoption decisions, including use of chemical fertilizers, improved seeds, and irrigation. We show that individuals with an internal locus of control have higher propensity of adopting agricultural technologies. We observe these empirical regularities in both datasets, and for both revealed measures......We investigate the implication of farmers’ locus of control on their technology adoption decisions. Our empirical analysis is based on two longitudinal surveys and hypothetical choice exercises conducted on Ethiopian farmers. We find that locus of control significantly predicts farmers’ technology...... of farmers’ technology adoption decisions as well as farmers’ hypothetical demand for agricultural technology. The results hold even in a more conservative fixed effects estimation approach, assuming locus of control as time-variant and dynamic behavioral trait. These findings provide behavioral...

  3. A canine chromosome 7 locus confers compulsive disorder susceptibility

    National Research Council Canada - National Science Library

    Dodman, N H; Karlsson, E K; Moon-Fanelli, A; Galdzicka, M; Perloski, M; Shuster, L; Lindblad-Toh, K; Ginns, E I

    2010-01-01

    ... pincher CCD with a chromosome 7 locus containing , an attractive candidate.Genome-wide association analyses were performed using DNA from 92 rigorously phenotyped Doberman pinscher FS BS cases and 6...

  4. Origin replication complex binding, nucleosome depletion patterns, and a primary sequence motif can predict origins of replication in a genome with epigenetic centromeres.

    Science.gov (United States)

    Tsai, Hung-Ji; Baller, Joshua A; Liachko, Ivan; Koren, Amnon; Burrack, Laura S; Hickman, Meleah A; Thevandavakkam, Mathuravani A; Rusche, Laura N; Berman, Judith

    2014-09-02

    Origins of DNA replication are key genetic elements, yet their identification remains elusive in most organisms. In previous work, we found that centromeres contain origins of replication (ORIs) that are determined epigenetically in the pathogenic yeast Candida albicans. In this study, we used origin recognition complex (ORC) binding and nucleosome occupancy patterns in Saccharomyces cerevisiae and Kluyveromyces lactis to train a machine learning algorithm to predict the position of active arm (noncentromeric) origins in the C. albicans genome. The model identified bona fide active origins as determined by the presence of replication intermediates on nondenaturing two-dimensional (2D) gels. Importantly, these origins function at their native chromosomal loci and also as autonomously replicating sequences (ARSs) on a linear plasmid. A "mini-ARS screen" identified at least one and often two ARS regions of ≥100 bp within each bona fide origin. Furthermore, a 15-bp AC-rich consensus motif was associated with the predicted origins and conferred autonomous replicating activity to the mini-ARSs. Thus, while centromeres and the origins associated with them are epigenetic, arm origins are dependent upon critical DNA features, such as a binding site for ORC and a propensity for nucleosome exclusion. DNA replication machinery is highly conserved, yet the definition of exactly what specifies a replication origin differs in different species. Here, we utilized computational genomics to predict origin locations in Candida albicans by combining locations of binding sites for the conserved origin replication complex, necessary for replication initiation, together with chromatin organization patterns. We identified predicted sequences that exhibited bona fide origin function and developed a linear plasmid assay to delimit the DNA fragments necessary for origin function. Additionally, we found that a short AC-rich motif, which is enriched in predicted origins, is required for

  5. Neurolinguistic programming training, trait anxiety, and locus of control.

    Science.gov (United States)

    Konefal, J; Duncan, R C; Reese, M A

    1992-06-01

    Training in the neurolinguistic programming techniques of shifting perceptual position, visual-kinesthetic dissociation, timelines, and change-history, all based on experiential cognitive processing of remembered events, leads to an increased awareness of behavioral contingencies and a more sensitive recognition of environmental cues which could serve to lower trait anxiety and increase the sense of internal control. This study reports on within-person and between-group changes in trait anxiety and locus of control as measured on the Spielberger State-Trait Anxiety Inventory and Wallston, Wallston, and DeVallis' Multiple Health Locus of Control immediately following a 21-day residential training in neurolinguistic programming. Significant with-in-person decreases in trait-anxiety scores and increases in internal locus of control scores were observed as predicted. Chance and powerful other locus of control scores were unchanged. Significant differences were noted on trait anxiety and locus of control scores between European and U.S. participants, although change scores were similar for the two groups. These findings are consistent with the hypothesis that this training may lower trait-anxiety scores and increase internal locus of control scores. A matched control group was not available, and follow-up was unfortunately not possible.

  6. [Health locus of control of patients in disease management programmes].

    Science.gov (United States)

    Schnee, M; Grikscheit, F

    2013-06-01

    Health locus of control beliefs plays a major role in improving self-management skills of the chronically ill - a main goal in disease management programmes (DMP). This study aims at characterising participants in disease management regarding their health locus of control. Data are based on 4 cross-sectional postal surveys between spring and autumn of 2006 and 2007 within the Health Care Monitor of the Bertelsmann Foundation. Among the 6 285 respondents, 1 266 are chronically ill and not enrolled in a DMP and 327 are participating in a DMP. A high internal locus of control (HLC) occurs significantly less often in DMP patients than in normal chronically ill patients (and healthy people) controlling for age, gender and social class. With increasing age, a high internal locus of control is also significantly less likely. When comparing healthy people, the chronically ill and the DMP participants a social gradient of a high internal locus of control belief can be observed. The weaker internal and higher doctor-related external locus of control of DMP participants should be carefully observed by the physician when trying to strengthen the patients' self-management skills. Evaluators of DMP should take into account the different baselines of DMP patients and relevant control groups and incorporate these differences into the evaluation. © Georg Thieme Verlag KG Stuttgart · New York.

  7. PENGARUH LOCUS OF CONTROL INTERNAL, LOCUS OF CONTROL EKSTERNAL, MANAJEMEN WAKTU, DAN KREATIVITAS MENGAJAR TERHADAP MOTIVASI BERPRESTASI

    Directory of Open Access Journals (Sweden)

    Dita Alfitami

    2017-10-01

    Full Text Available The aims of this research were to know the influence of the internal locus of control, external locus of control, time management, and teaching creativity to achievement motivation (case study in introduction to Office Administration subject in class XI AP SMK N 1 Kendal lesson school year 2016/2017.The population in this study were all the tenth graders of the Office Administration study program at SMK Negeri 1 Kendal with the total number of 71 students. While the sample taken used was saturated samples because the population were less than 100 respondents. Data collection method used in this research, which use questionnaire. The data analysis using multiple linear regression analysis method, classic assumption test analysis, percentage descriptive analysis, and hypothesis test analysis with the help of SPSS 21 programs. The finding shows the results of multiple linear regression analysis obtained equation Y = -20,466 + 0,431 X1 + 0,301 X2 + 0,357 X3 + 0,364 X4+ e. Test of significance of regression equation with F test, obtained count = 43,846 with significance0.000 and less than 0,05. The amount of influence simultaneously or together from locus of control, external locus of control, time management, and teaching creativity to achievement motivation was71%. While influence in partial or individually for internal locus of control was 23,52%, external locus of control 12,67%, time management 22,84%, and teaching creativity 22,46%.

  8. RepB proteins of the multipartite Rhizobium leguminosarum bv. trifolii genome discriminate between centromere-like parS sequences for plasmid segregational stability.

    Science.gov (United States)

    Koper, Piotr; Żebracki, Kamil; Marczak, Małgorzata; Skorupska, Anna; Mazur, Andrzej

    2016-11-01

    The plasmids of the Rhizobiaceae family members and other Alphaproteobacteria are usually large, low copy-number and contain all elements necessary for active segregation and replication located in one operon comprising repABC genes. The genome of Rhizobium leguminosarum bv. trifolii TA1 (RtTA1) consists of a chromosome and four plasmids (pRleTA1a-d) with repABC operons. In this work, centromere-binding RepB proteins of four RtTA1 plasmids were studied. Stability assays of the truncated derivatives of repABC cassettes demonstrated that RepA, RepB proteins and parS-like elements constituted plasmid partitioning systems, while RepC were sufficient for their replication. Individual RepB proteins bound specifically to centromere-like parS elements of the parental plasmids, which was crucial step toward the proper segregation of plasmids into daughter cells. RtTA1 RepB proteins formed dimers and oligomers in the solution. The C-terminal part of RepB was responsible for dimerization, while the domain engaged in parS binding was located in the middle of the protein. It was concluded that the specific interaction between individual RepB proteins and their target sequences together with the substantial diversity of the Rep proteins and parS originating from different plasmids strongly contributed to the coexistence of several plasmids equipped with similar repABC cassettes in the multipartite bacterial genome. © 2016 John Wiley & Sons Ltd.

  9. High-resolution meiotic and physical mapping of the Best`s vitelliform macular dystrophy (VMD2) locus to pericentromeric chromosome 11

    Energy Technology Data Exchange (ETDEWEB)

    Weber, B.H.F.; Vogt, G. [Institut fuer Humangenetik, Wuerzburg (Germany); Walker, D. [UBC, Vancouver (Canada)] [and others

    1994-09-01

    Vitelliform macular dystrophy, also known as Best`s disease, is a juvenile-onset macular degeneration with autosomal dominant inheritance. It is characterized by well-demarcated accumulation of lipofuscin-like material within and beneath the retinal pigment epithelium (RPE) and classically results in an egg yolk-like appearance of the macula. Typically, carriers of the disease gene show a specific electrophysiological sign which can be detected by electrooculography (EOG). The EOG measures a standing potential between the cornea and the retina which is primarily generated by the RPE. The histopathological findings as well as the EOG abnormalities suggest that Best`s disease is a generalized disorder of the RPE. The basic biochemical defect is still unknown. As a first step in the positional cloning of the defective gene, the Best`s disease locus was mapped to chromosome 11 between markers at D11S871 and INT2. Subsequently, his region was refined to a 3.7 cM interval flanked by loci D11S903 and PYGM. To further narrow the D11S903-PYGM interval and to obtain an estimate of the physical size of the minimal candidate region, we used a combination of high-resolution PCR hybrid mapping and analysis of recombinant Best`s disease chromosomes. We identified six markers from within the D11S903-PYGM interval that show no recombination with the defective gene in three multigeneration Best`s disease pedigrees. Our hybrid panel localizes these markers on either side of the centromere on chromosome 11. The closest markers flanking the disease gene are at D11S986 in band p12-11.22 and at D11S480 in band q13.2-13.3. Our study demonstrates that the physical size of the Best`s disease region is exceedingly larger than was previously estimated from the genetic data due to the proximity of the defective gene to the centromere of chromosome 11.

  10. Inferring Demographic History Using Two-Locus Statistics.

    Science.gov (United States)

    Ragsdale, Aaron P; Gutenkunst, Ryan N

    2017-06-01

    Population demographic history may be learned from contemporary genetic variation data. Methods based on aggregating the statistics of many single loci into an allele frequency spectrum (AFS) have proven powerful, but such methods ignore potentially informative patterns of linkage disequilibrium (LD) between neighboring loci. To leverage such patterns, we developed a composite-likelihood framework for inferring demographic history from aggregated statistics of pairs of loci. Using this framework, we show that two-locus statistics are more sensitive to demographic history than single-locus statistics such as the AFS. In particular, two-locus statistics escape the notorious confounding of depth and duration of a bottleneck, and they provide a means to estimate effective population size based on the recombination rather than mutation rate. We applied our approach to a Zambian population of Drosophila melanogaster Notably, using both single- and two-locus statistics, we inferred a substantially lower ancestral effective population size than previous works and did not infer a bottleneck history. Together, our results demonstrate the broad potential for two-locus statistics to enable powerful population genetic inference. Copyright © 2017 by the Genetics Society of America.

  11. Impulsiveness, locus of control, motivation and problem gambling.

    Science.gov (United States)

    Clarke, Dave

    2004-01-01

    A questionnaire consisting of demographic items, questions about gambling behavior, the South Oaks Gambling Screen (SOGS), a depression inventory, the Eysenck Impulsiveness Questionnaire, Levenson's Internality, Powerful Others and Chance Scales of locus of control and the Gambling Motivation Scale, was completed by a non-random sample of 147 New Zealand university students who gambled for money, median age 24 years. Approximately 17 of the sample was classified as problem gamblers, the rest as non-problem gamblers. Multivariate analysis of variance showed that there were significant differences between problem and non-problem gamblers on gambling frequency, number of activities, parents' gambling, depression, impulsiveness and motivation, but not on locus of control. Amotivation (apathy) and motivation towards stimulation correlated with powerful others and chance locus of control, and motivation to impress others with powerful others locus of control. Hierarchical regression analysis showed that: (1) beyond gambling frequency, number of activities and parents' gambling, motivation explained a substantial proportion of variance in SOGS scores, with impulsiveness accounting for a lesser amount, and (2) predictors of problem gambling included impulsiveness, amotivation and the motivations for accomplishment and tension release. It was concluded that gambling motivation is a more useful construct than locus of control in explaining problem gambling. Suggestions were made for future research, and aspects of gambling motivation were discussed in terms of a treatment program with groups of problem gamblers.

  12. Mutation at the Human D1S80 Minisatellite Locus

    Directory of Open Access Journals (Sweden)

    Kuppareddi Balamurugan

    2012-01-01

    Full Text Available Little is known about the general biology of minisatellites. The purpose of this study is to examine repeat mutations from the D1S80 minisatellite locus by sequence analysis to elucidate the mutational process at this locus. This is a highly polymorphic minisatellite locus, located in the subtelomeric region of chromosome 1. We have analyzed 90,000 human germline transmission events and found seven (7 mutations at this locus. The D1S80 alleles of the parentage trio, the child, mother, and the alleged father were sequenced and the origin of the mutation was determined. Using American Association of Blood Banks (AABB guidelines, we found a male mutation rate of 1.04×10-4 and a female mutation rate of 5.18×10-5 with an overall mutation rate of approximately 7.77×10-5. Also, in this study, we found that the identified mutations are in close proximity to the center of the repeat array rather than at the ends of the repeat array. Several studies have examined the mutational mechanisms of the minisatellites according to infinite allele model (IAM and the one-step stepwise mutation model (SMM. In this study, we found that this locus fits into the one-step mutation model (SMM mechanism in six out of seven instances similar to STR loci.

  13. A two-locus forensic match probability for subdivided populations.

    Science.gov (United States)

    Ayres, K L

    2000-01-01

    A two-locus match probability is presented that incorporates the effects of within-subpopulation inbreeding (consanguinity) in addition to population subdivision. The usual practice of calculating multi-locus match probabilities as the product of single-locus probabilities assumes independence between loci. There are a number of population genetics phenomena that can violate this assumption: in addition to consanguinity, which increases homozygosity at all loci simultaneously, gametic disequilibrium will introduce dependence into DNA profiles. However, in forensics the latter problem is usually addressed in part by the careful choice of unlinked loci. Hence, as is conventional, we assume gametic equilibrium here, and focus instead on between-locus dependence due to consanguinity. The resulting match probability formulae are an extension of existing methods in the literature, and are shown to be more conservative than these methods in the case of double homozygote matches. For two-locus profiles involving one or more heterozygous genotypes, results are similar to, or smaller than, the existing approaches.

  14. Transcriptional analysis of the Streptococcus pyogenes salivaricin locus.

    Science.gov (United States)

    Namprachan-Frantz, Phanramphoei; Rowe, Hannah M; Runft, Donna L; Neely, Melody N

    2014-02-01

    The sal lantibiotic locus plays an important role in the virulence of Streptococcus pyogenes. Our transcriptional analysis of the sal locus provides new information on the complex regulation of this operon. Transcription of the operon is regulated by a promoter upstream of the operon and by a second internal promoter upstream of the salKRZ genes. Here we identify the location of the internal promoter and provide information on how this promoter is autoregulated by proteins within the locus. We determined by primer extension that the salKR promoter is located within the salY gene and identified several regulatory regions important for expression. The higher activity of the promoter in a salKR deletion strain indicates a role in repression by the SalR response regulator. Further, this promoter had higher activity in a salA deletion strain, implicating corepression or a signaling role for the SalA peptide. Finally, we demonstrate that this promoter can be controlled by host factors. Analysis of transcriptional regulation of this locus provides a better understanding of the function of the sal locus in S. pyogenes pathogenesis.

  15. AKT as Locus of Hydrogen Bond Network in Cancer.

    Science.gov (United States)

    Radisavljevic, Ziv

    2018-01-01

    Generation and maintenance of a cancer complexity and robustness are impossible without hydrogen element. It is essential element for the cancer signaling through the AKT locus. Hyperactivated AKT locus by a positive feedback loops from the cancer hypoxic microenvironment generates a hydrogen bond network. Such network initiates protein-protein interaction at the AKT active site and at the same time stabilizes signal propagation. A hydrogen bond network conforms an entropy/enthalpy energetic process used for the interconversion of the AKT protein in metastasis formation and maintenance. Targeting the AKT locus by the redox balance change or hydrogen balance change or proton beam radiation disrupts a hydrogen bond network leading to the disappearance of a cancer complexity and robustness causing failure of the complex energy system in solid cancers and hematological malignancy. J. Cell. Biochem. 119: 130-133, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Lupus vulgaris occurring in a locus minoris resistentiae.

    Science.gov (United States)

    Long, Richard; Beatch, Anita; Lee, Mao-Cheng; Cheung-Lee, Melody; Wasel, Norman

    2009-01-01

    The pathogenesis of lupus vulgaris, a form of cutaneous tuberculosis, is not always clear, especially in patients who do not have coexistent extracutaneous tuberculosis and in patients with single lesions. To report a case of lupus vulgaris in a locus minoris resistentiae (a site of reduced resistance) and to use a unique set of clinical circumstances and laboratory tests to reconstruct the pathogenesis of the lesion and the response to treatment. Lupus vulgaris can occur in a locus minoris resistentiae; local trauma and possibly other factors, such as increased temperature, topical corticosteroids, and the virulence of the infecting strain, may facilitate the growth of Mycobacterium tuberculosis present at a locus minoris resistentiae as a result of a silent bacillemia.

  17. Parenting style, locus of control, and oral hygiene in adolescents.

    Science.gov (United States)

    Aleksejūnienė, Jolanta; Brukienė, Vilma

    2012-01-01

    The aim of the study was to test if variations in oral hygiene levels in adolescents were associated with locus of control and parenting styles after controlling for demographic factors. The study sample comprised 237 adolescents aged 12-13 years. The structured questionnaire included demographic characteristics and items about parenting style and locus of control. The Individual Quantitative Plaque % Index (IQPI) and toothbrushing frequency were used as clinical outcome measures. In the bivariate analyses, socioeconomic status (P=0.012), number of children in the family (P=0.003), and frequency of toothbrushing (P=0.001) were related to dental plaque levels. Gender (Pparenting styles, locus of control, and oral hygiene levels was not confirmed.

  18. Locus-specific view of flax domestication history

    Science.gov (United States)

    Fu, Yong-Bi; Diederichsen, Axel; Allaby, Robin G

    2012-01-01

    Crop domestication has been inferred genetically from neutral markers and increasingly from specific domestication-associated loci. However, some crops are utilized for multiple purposes that may or may not be reflected in a single domestication-associated locus. One such example is cultivated flax (Linum usitatissimum L.), the earliest oil and fiber crop, for which domestication history remains poorly understood. Oil composition of cultivated flax and pale flax (L. bienne Mill.) indicates that the sad2 locus is a candidate domestication locus associated with increased unsaturated fatty acid production in cultivated flax. A phylogenetic analysis of the sad2 locus in 43 pale and 70 cultivated flax accessions established a complex domestication history for flax that has not been observed previously. The analysis supports an early, independent domestication of a primitive flax lineage, in which the loss of seed dispersal through capsular indehiscence was not established, but increased oil content was likely occurred. A subsequent flax domestication process occurred that probably involved multiple domestications and includes lineages that contain oil, fiber, and winter varieties. In agreement with previous studies, oil rather than fiber varieties occupy basal phylogenetic positions. The data support multiple paths of flax domestication for oil-associated traits before selection of the other domestication-associated traits of seed dispersal loss and fiber production. The sad2 locus is less revealing about the origin of winter tolerance. In this case, a single domestication-associated locus is informative about the history of domesticated forms with the associated trait while partially informative on forms less associated with the trait. PMID:22408732

  19. Analysis of the ABCA4 genomic locus in Stargardt disease

    DEFF Research Database (Denmark)

    Zernant, Jana; Xie, Yajing Angela; Ayuso, Carmen

    2014-01-01

    was designed to find the missing disease-causing ABCA4 variation by a combination of next-generation sequencing (NGS), array-Comparative Genome Hybridization (aCGH) screening, familial segregation and in silico analyses. The entire 140 kb ABCA4 genomic locus was sequenced in 114 STGD patients with one known...... excluded since they were not conserved in non-human primates, were frequent in African populations and, therefore, represented ancestral, and not disease-associated, variants. The sequence variability in the ABCA4 locus is extensive and the non-coding sequences do not harbor frequent mutations in STGD...

  20. Correlacional study among locus of control and human values

    OpenAIRE

    Saulo Santos Menezes Almeida

    2008-01-01

    O presente estudo teve como objetivo central analisar as relações entre locus de controle e valores. Participaram 355 universitários de Sergipe, a maioria do sexo feminino (62,8%) e solteiros (80%), com média de idade de 25,68 anos (amplitude de 17 a 56 anos). Os estudantes responderam à escala de locus de controle de Reyes e a escala de valores de Schwartz. Os resultados indicaram ser os instrumentos aptos a mensurar o proposto pelo objetivo, apresentando índices psicométricos satisfatórios....

  1. Hispanics' locus of control, acculturation, and wellness attitudes.

    Science.gov (United States)

    Valentine, Sean R; Godkin, Jennie; Doughty, Graeme P

    2008-01-01

    There is reason to believe that various cultural attitudes and beliefs influence certain health behaviors, and additional research should identify the causes of such behaviors. This study explored the relationships among cultural identity, acculturation, locus of control, and health beliefs using a sample of 110 Hispanic individuals taking college classes in the southern or southwestern United States. Path analysis indicated that an external locus of control was positively related to health barrier perceptions and that acculturation was negatively related to health barrier perceptions. The findings suggest that Hispanics' perceived control over health outcomes and positive health beliefs could be enhanced with culturally perceptive counseling.

  2. Relationship between preference for red and locus of control.

    Science.gov (United States)

    Singg, S; Whiddon, T L

    2000-08-01

    The validity of the assumptions about the color red in the Lüscher color theory were examined by correlating preference for red to locus of control and sex. Undergraduates (100 men and 100 women) who scored or = 16 on the Rotter Internal-External Locus of Control Scale were administered the short form of the Lüscher Color Test. Consistent with the assumptions by Lüscher about the color red, the analysis of variance showed that Internal scorers preferred red significantly more than External scorers, but no sex difference was found.

  3. Heterotic trait locus (HTL mapping identifies intra-locus interactions that underlie reproductive hybrid vigor in Sorghum bicolor.

    Directory of Open Access Journals (Sweden)

    Imri Ben-Israel

    Full Text Available Identifying intra-locus interactions underlying heterotic variation among whole-genome hybrids is a key to understanding mechanisms of heterosis and exploiting it for crop and livestock improvement. In this study, we present the development and first use of the heterotic trait locus (HTL mapping approach to associate specific intra-locus interactions with an overdominant heterotic mode of inheritance in a diallel population using Sorghum bicolor as the model. This method combines the advantages of ample genetic diversity and the possibility of studying non-additive inheritance. Furthermore, this design enables dissecting the latter to identify specific intra-locus interactions. We identified three HTLs (3.5% of loci tested with synergistic intra-locus effects on overdominant grain yield heterosis in 2 years of field trials. These loci account for 19.0% of the heterotic variation, including a significant interaction found between two of them. Moreover, analysis of one of these loci (hDPW4.1 in a consecutive F2 population confirmed a significant 21% increase in grain yield of heterozygous vs. homozygous plants in this locus. Notably, two of the three HTLs for grain yield are in synteny with previously reported overdominant quantitative trait loci for grain yield in maize. A mechanism for the reproductive heterosis found in this study is suggested, in which grain yield increase is achieved by releasing the compensatory tradeoffs between biomass and reproductive output, and between seed number and weight. These results highlight the power of analyzing a diverse set of inbreds and their hybrids for unraveling hitherto unknown allelic interactions mediating heterosis.

  4. Heterotic trait locus (HTL) mapping identifies intra-locus interactions that underlie reproductive hybrid vigor in Sorghum bicolor.

    Science.gov (United States)

    Ben-Israel, Imri; Kilian, Benjamin; Nida, Habte; Fridman, Eyal

    2012-01-01

    Identifying intra-locus interactions underlying heterotic variation among whole-genome hybrids is a key to understanding mechanisms of heterosis and exploiting it for crop and livestock improvement. In this study, we present the development and first use of the heterotic trait locus (HTL) mapping approach to associate specific intra-locus interactions with an overdominant heterotic mode of inheritance in a diallel population using Sorghum bicolor as the model. This method combines the advantages of ample genetic diversity and the possibility of studying non-additive inheritance. Furthermore, this design enables dissecting the latter to identify specific intra-locus interactions. We identified three HTLs (3.5% of loci tested) with synergistic intra-locus effects on overdominant grain yield heterosis in 2 years of field trials. These loci account for 19.0% of the heterotic variation, including a significant interaction found between two of them. Moreover, analysis of one of these loci (hDPW4.1) in a consecutive F2 population confirmed a significant 21% increase in grain yield of heterozygous vs. homozygous plants in this locus. Notably, two of the three HTLs for grain yield are in synteny with previously reported overdominant quantitative trait loci for grain yield in maize. A mechanism for the reproductive heterosis found in this study is suggested, in which grain yield increase is achieved by releasing the compensatory tradeoffs between biomass and reproductive output, and between seed number and weight. These results highlight the power of analyzing a diverse set of inbreds and their hybrids for unraveling hitherto unknown allelic interactions mediating heterosis.

  5. Quantitative trait locus (QTL) mapping for 100-kernel weight of ...

    African Journals Online (AJOL)

    hope&shola

    2010-12-06

    Dec 6, 2010 ... Abbreviations: KW, 100-kernel weight; CIM, composite interval mapping; CV, coefficient of variation; HNR, high nitrogen regime; LNR, low nitrogen regime; LOD, log10 of odds ratio;. MAS, marker-assisted selection; QTL, quantitative trait locus;. R2, percentage of phenotypic variance explained by QTL; RIL,.

  6. New distal marker closely linked to the fragile X locus

    NARCIS (Netherlands)

    Hulsebos, T. J.; Oostra, B. A.; Broersen, S.; Smits, A.; van Oost, B. A.; Westerveld, A.

    1991-01-01

    We have isolated II-10, a new X-chromosomal probe that identifies a highly informative two-allele TaqI restriction fragment length polymorphism at locus DXS466. Using somatic cell hybrids containing distinct portions of the long arm of the X chromosome, we could localize DXS466 between DXS296 and

  7. New distal marker closely linked to the fragile X locus

    NARCIS (Netherlands)

    T. Hulsebos (Theo); B.A. Oostra (Ben); A. Broersen (Alexander); A. Smits; B.A. van Oost (B.); A. Westerveld (Andries)

    1991-01-01

    textabstractWe have isolated II-10, a new X-chromosomal probe that identifies a highly informative two-allele TaqI restriction fragment length polymorphism at locus DXS466. Using somatic cell hybrids containing distinct portions of the long arm of the X chromosome, we could localize DXS466 between

  8. Male-pattern baldness susceptibility locus at 20p11.

    NARCIS (Netherlands)

    Richards, J.B.; Yuan, X.; Geller, F.; Waterworth, D.; Bataille, V.; Glass, D.; Song, K.; Waeber, G.; Vollenweider, P.; Aben, K.K.H.; Kiemeney, L.A.L.M.; Walters, B.; Soranzo, N.; Thorsteinsdottir, U.; Kong, A.; Rafnar, T.; Deloukas, P.; Sulem, P.; Stefansson, H.; Stefansson, K.; Spector, T.D.; Mooser, V.

    2008-01-01

    We conducted a genome-wide association study for androgenic alopecia in 1,125 men and identified a newly associated locus at chromosome 20p11.22, confirmed in three independent cohorts (n = 1,650; OR = 1.60, P = 1.1 x 10(-14) for rs1160312). The one man in seven who harbors risk alleles at both

  9. Emotional Intelligence, Locus of Control and Conflict Handling Skills ...

    African Journals Online (AJOL)

    This study examined Emotional Intelligence, Locus of control and Conflict Handling Skills as Predictors of non-violent behaviours among University Students in South-Western Nigeria. The population was all the Nigerian University Students in the South-Western Nigerian out of which a sample of 1,000 participants were ...

  10. AUTOMATIC GENERATION OF ROOT LOCUS PLOTS FOR LINEAR ...

    African Journals Online (AJOL)

    Design and analysis of control systems often become difficult due to the complexity of the system model and the design techniques involved. This paper presents the development of a Tools Box in Microsoft Excel for control engineer that uses root locus as a time domain technique for system design and analysis. The Tool ...

  11. Exploring Learner Autonomy: Language Learning Locus of Control in Multilinguals

    Science.gov (United States)

    Peek, Ron

    2016-01-01

    By using data from an online language learning beliefs survey (n?=?841), defining language learning experience in terms of participants' multilingualism, and using a domain-specific language learning locus of control (LLLOC) instrument, this article examines whether more experienced language learners can also be seen as more autonomous language…

  12. Relationships among Impulsiveness, Locus of Control, Sex, and Music Practice

    Science.gov (United States)

    Miksza, Peter

    2006-01-01

    This study is an investigation of relationships among impulsiveness, locus of control, sex, observed practice behaviors, practice effectiveness, and self-reported practice habits in a sample of 40 college brass players. Practice effectiveness was defined by the amount of change in pretest and posttest performance achievement scores over one…

  13. Comparison of Locus of Control with Levels of Creativity.

    Science.gov (United States)

    Kneipp, Karen B.; Gadzella, Bernadette M.

    This study was undertaken to determine whether external locus of control orientation was significantly negatively correlated with levels of creativity. Subjects were 13 male and 13 female undergraduate students enrolled in psychology classes at a southwestern university. Mean age of the subjects was 28.6. Instruments used were Levenson's (1972) I…

  14. Dealing with Malfunction: Locus of Control in Web-Conferencing

    Science.gov (United States)

    Klebl, Michael

    2014-01-01

    This paper considers how students deal with malfunctions that occur during the use of web conferencing systems in learning arrangements. In a survey among participants in online courses that make use of a web-conferencing system (N = 129), the relationship between a preference for internal or external locus of control and the perception of…

  15. Demographic Determinants of Locus of Control among Medical ...

    African Journals Online (AJOL)

    The Levenson Multidimensional Locus of Control Inventory and a Socio - demographic data collection sheet were used to collect data from 262 (183 males and 79 females) students selected through convenience sampling. Data were th analyzed using the 16th version of the SPPS. Percentages, means, t-test and ANOVA ...

  16. Social support, locus of control, and psychological well-being

    NARCIS (Netherlands)

    van der Zee, KI; Buunk, BP; Sanderman, R

    1997-01-01

    Social support seems to be positively related to psychological well-being. Studies have shown that individual differences exist in the ability to mobilize and use sources of support. The current study focused on locus of control as a personality factor that might be related to this ability, In 2

  17. Locus of control and investment in risky assets

    NARCIS (Netherlands)

    Salamanca Acosta, Nicolas; de Grip, A.; Fouarge, Didier; Montizaan, Raymond

    2016-01-01

    We show that household heads with a strong internal economic locus of control are more likely to hold equity and hold a larger share of equity in their investment portfolio. This relation holds when we control for economic preferences and possible confounders such as financial literacy,

  18. Refinement of the locus for non-syndromic sensorineural deafness ...

    Indian Academy of Sciences (India)

    Unknown

    2004-04-05

    Bergstrom et al. 1971). Several X-linked forms of isolated bilateral hearing impairment have been reported and their classification is based on the mode of onset and audiogram data (Gorlin 1995). Genetically, the locus DFN1 had been ...

  19. Response to selection in finite locus models with nonadditive effects

    NARCIS (Netherlands)

    Esfandyari, Hadi; Henryon, Mark; Berg, Peer; Thomasen, Jørn Rind; Bijma, Piter; Sørensen, Anders Christian

    2017-01-01

    Under the finite-locus model in the absence of mutation, the additive genetic variation is expected to decrease when directional selection is acting on a population, according to quantitative-genetic theory. However, some theoretical studies of selection suggest that the level of additive

  20. A multi-locus phylogenetic evaluation of Diaporthe (Phomopsis)

    NARCIS (Netherlands)

    Udayanga, D.; Liu, X.; Crous, P.W.; McKenzie, E.H.C.; Chukeatirote, E.; Hyde, K.D.

    2012-01-01

    The genus Diaporthe (Phomopsis) includes important plant pathogenic fungi with wide host ranges and geographic distributions. In the present study, phylogenetic species recognition in Diaporthe is re-evaluated using a multi-locus phylogeny based on a combined data matrix of rDNA ITS, and partial

  1. Concept -Mapping, Students' Locus of Control and Gender as ...

    African Journals Online (AJOL)

    This study investigated the relative effectiveness of concept mapping and lecture methods on the academic achievement of Nigerian High School Studies in biology using gender and locus of control as intervening variables. This study made use of a 2 x 2 x 2 non-randomised control group, pretest - posttest ...

  2. Locus of control and learning strategies as predictors of academic ...

    African Journals Online (AJOL)

    The aim of the research was to determine the relationships which exist between academic success, learning strategies and locus of control. In order to achieve this aim a small-scale quantitative study, utilising two inventories, was done. The first measuring instrument is the Learning and Study Strategies Inventory, which is ...

  3. automatic generation of root locus plots for linear time invariant

    African Journals Online (AJOL)

    user

    other software package and the ease of using it on the readily available Microsoft Excel environment. Keywords: Asymptotes, Poles, Root Locus, Singularity Point, Zeros. 1. INTRODUCTION. The evolution of Control Engineering practice has propelled the performance of any design system to a reasonable satisfaction which ...

  4. Screening for genomic rearrangements at BRCA1 locus in Iranian ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 92; Issue 1. Screening for genomic rearrangements at BRCA1 locus in Iranian women with breast cancer using multiplex ligation-dependent probe amplification. Vahid R. Yassaee Babak Emamalizadeh Mir Davood Omrani. Research Note Volume 92 Issue 1 April 2013 pp 131- ...

  5. Inferring relationships between pairs of individuals from locus heterozygosities

    Directory of Open Access Journals (Sweden)

    Spinetti Isabella

    2002-11-01

    Full Text Available Abstract Background The traditional exact method for inferring relationships between individuals from genetic data is not easily applicable in all situations that may be encountered in several fields of applied genetics. This study describes an approach that gives affordable results and is easily applicable; it is based on the probabilities that two individuals share 0, 1 or both alleles at a locus identical by state. Results We show that these probabilities (zi depend on locus heterozygosity (H, and are scarcely affected by variation of the distribution of allele frequencies. This allows us to obtain empirical curves relating zi's to H for a series of common relationships, so that the likelihood ratio of a pair of relationships between any two individuals, given their genotypes at a locus, is a function of a single parameter, H. Application to large samples of mother-child and full-sib pairs shows that the statistical power of this method to infer the correct relationship is not much lower than the exact method. Analysis of a large database of STR data proves that locus heterozygosity does not vary significantly among Caucasian populations, apart from special cases, so that the likelihood ratio of the more common relationships between pairs of individuals may be obtained by looking at tabulated zi values. Conclusions A simple method is provided, which may be used by any scientist with the help of a calculator or a spreadsheet to compute the likelihood ratios of common alternative relationships between pairs of individuals.

  6. Relationship Among Achievement Motivation, Self-Esteem, Locus of ...

    African Journals Online (AJOL)

    The thrust of the study was to examine the relationship among achievement motivation, self-esteem, locus of control and academic performance of university students in a Nigerian University. The purpose was to determine the extent university student\\'s academic performance was influenced by these criterion variables.

  7. Influence of Locus Control on Real and Perceived Relationships ...

    African Journals Online (AJOL)

    They included the Nowicki-Strickland Internal – External Locus of Control Scale for children by Nowicki and Strickland (1973) and Emotional – Social Loneliness Inventory by Vincenzi and Grabosky, (1987). A cross sectional survey design was used while regression analysis and multivariate statistics were used in data ...

  8. Relationship between internet addiction and academic locus of ...

    African Journals Online (AJOL)

    The study identified the various internet activities engaged in by students in a Nigerian University and examined the relationship between internet addiction and their academic locus of control. The sample was made of 250 students selected from a University in Nigeria. An instrument tagged “Questionnaire on Students' ...

  9. Comparison of multi-locus enzyme and protein gel electrophoresis ...

    African Journals Online (AJOL)

    Comparison of multi-locus enzyme and protein gel electrophoresis in the discrimination of five Fusarium species isolated from Egyptian cottons. ... resolution in organizing all isolates in their respective species-specific clusters. A low correlations was detected between geographical origin of isolates and genetic diversity.

  10. Sam Karlin and multi-locus population genetics.

    Science.gov (United States)

    Feldman, Marcus W

    2009-06-01

    Between 1967 and 1982, Sam Karlin made fundamental contributions to many areas of deterministic population genetic theory. This remembrance focuses on his work in multi-locus population genetics, primarily on the interaction between genotypic selection and the rate of recombination.

  11. The Influence of Locus of Control on Student Financial Behavior

    Science.gov (United States)

    Britt, Sonya; Cumbie, Julie A.; Bell, Mary M.

    2013-01-01

    Data on psychological influences of financial behaviors has not been well addressed in student populations, which is concerning given the high levels of general and financial stress experienced by college students. The findings of this study indicate that college students with an external locus of control exhibit the worst financial behaviors.…

  12. 40 CFR 798.5195 - Mouse biochemical specific locus test.

    Science.gov (United States)

    2010-07-01

    ... pattern. Presumed mutants are bred to confirm the genetic nature of the change. (3) Animal selection—(i... SUBSTANCES CONTROL ACT (CONTINUED) HEALTH EFFECTS TESTING GUIDELINES Genetic Toxicity § 798.5195 Mouse...) A biochemical specific locus mutation is a genetic change resulting from a DNA lesion causing...

  13. Gender, Age and Locus of Control as Correlates of Remedial ...

    African Journals Online (AJOL)

    The study sought to explain remedial learners' attitude towards English language using three variables: gender, age and locus of control. Three properly validated instruments were used to collect data on the relevant variables from 385 remedial English learners randomly selected from 5 remedial education centers in ...

  14. Locus of Control and Smokeless Tobacco Use Among Adolescents.

    Science.gov (United States)

    Dignan, Mark; And Others

    1986-01-01

    Surveyed seventh-grade students from two school districts in rural North Carolina to determine the prevalence and correlates of smokeless tobacco use. Of those reporting use of smokeless tobacco, virtually all were male. Locus of control of "occasional" users was significantly more internal than those reporting "regular" use.…

  15. Exploring the relationship between work locus of control and job ...

    African Journals Online (AJOL)

    Therefore, to improve the performance of commercial banks in Nigeria, employer of labour should resharpen recruitment tools in a way that can identify candidates with internal work locus of control for appointment. Management of Commercial Banks in Nigeria should equally organise training programs that can boost ...

  16. Locus of the intensity effect in simple reaction time tasks

    NARCIS (Netherlands)

    Jaśkowski, Piotr; Kurczewska, Marta; Nowik, Agnieszka; van der Lubbe, Robert Henricus Johannes; Verleger, Rolf

    2007-01-01

    Evidence is still inconclusive regarding the locus of the stimulus intensity effect on information processing in reaction tasks. Miller, Ulrich, and Rinkenauer (1999) addressed this question by assessing the intensity effect on stimulus- and response-locked lateralized readiness potentials (LRPs) as

  17. Determination of the yield locus by means of temperature measurement

    NARCIS (Netherlands)

    Banabic, D.; Huetink, Han

    2006-01-01

    The paper presents a theoretical background of the thermo-graphical method of determining the yield locus. The analytical expression of the temperature variation of the specimen deformed in the elastic state is determined starting from the first law of thermodynamics. The experimental method for

  18. (PLWHA): influence of social support, self-esteem, health locus

    African Journals Online (AJOL)

    Coping among people living with HIV/AIDS (PLWHA): influence of social support, self-esteem, health locus of control and gender. ... 73) = 5.59, p.05). It is then concluded that management of HIV/AIDS should ...

  19. Y-Chromosome short tandem repeat, typing technology, locus ...

    African Journals Online (AJOL)

    Y-Chromosome short tandem repeat, typing technology, locus information and allele frequency in different population: A review. ... This review will highlight the importance of the Y- Chromosome as a tool for tracing human evolution and describes some details of Y-chromosomal short tandem repeat (STR) analysis. Among ...

  20. Influence of organisational climate and locus of control on job ...

    African Journals Online (AJOL)

    This study examined the influence of perceived organisational climate and locus of control on job satisfaction and turnover intentions of commercial bank workers in Benin, Edo State, Nigeria. To determine this, a 2X2 ANOVA was used to analyse the data. Results from a field study of 200 employees of 25 commercial banks ...

  1. Influences of peer relations and locus of control on students ...

    African Journals Online (AJOL)

    Effort to checkmate extravagance and maximize gain is the focus of all organizations more in this period of global financial crisis. There is need therefore to checkmate unnecessary financial spending. This study examines the influence of the variables, peer relations and locus of control, on such spending among University ...

  2. 240 INFLUENCES OF PEER RELATIONS AND LOCUS OF ...

    African Journals Online (AJOL)

    therefore to checkmate unnecessary financial spending. This study examines the influence of the variables, peer relations and locus of control, on such spending among University students. Three hundred (144 males and 156 females) participants were used for the study. Their ages ranged between 20-30 years with mean ...

  3. Emotional intelligence and locus of control of adult patients with ...

    African Journals Online (AJOL)

    Background: This article investigates emotional intelligence and locus of control in an adult breast cancer population receiving treatment. Gaining insight into these constructs will contribute to improving breast cancer patients' psychological well-being and to reducing physical vulnerability to disease before and during ...

  4. Health locus of control and internal resilience factors among ...

    African Journals Online (AJOL)

    ... the Multidimensional Health Locus of Control Scale (MHLC) (Wallston et al., 1978:165) and a modified version of the Resilience Scale (Wagnild & Young, 1993:160). Analysis of variance of the loci of control and resilience scores were conducted. Although 78% of the resilience scores were well within the moderate range, ...

  5. Locus of Control and Learning Disabilities: A Review and Discussion.

    Science.gov (United States)

    Dudley-Marling, Curtis C.; And Others

    1982-01-01

    A literature review reveals that learning disabled children are more likely than normal achievers to attribute successes, but not failures, to external factors. The implications of locus of control for the field of learning disabilities are discussed in terms of its relation to academic achievement, learned helplessness, and remediation programs.…

  6. Communication Anxiety, Self-Image, and Locus of Control.

    Science.gov (United States)

    McGary, Lois J.; Parks, Arlie Muller

    A study was conducted (1) to determine the effectiveness of a specially designed one-semester basic speech course on the self-image of college students experiencing extreme communication anxiety, and (2) to discover whether a difference existed between the self-image of students who had an external locus of control and those with an internal locus…

  7. DNA marker mining of ILSTS035 microsatellite locus on ...

    Indian Academy of Sciences (India)

    We describe tests for detecting and locating quantitative trait loci (QTL) for traits in Hanwoo cattle. From results of a permutation test to detect QTL for marbling, we selected the microsatellite locus ILSTS035 on chromosome 6 for further analysis. -means clustering analysis applied to five traits and nine DNA markers in ...

  8. Evolutionary process of a tetranucleotide microsatellite locus in Acipenseriformes.

    Science.gov (United States)

    Shao, Zhao Jun; Rivals, Eric; Zhao, Na; Lek, Sovan; Chang, Jianbo; Berrebi, Patrick

    2011-08-01

    The evolutionary dynamics of the tetra-nucleotide microsatellite locus Spl-106 were investigated at the repeat and flanking sequences in 137 individuals of 15 Acipenseriform species, giving 93 homologous sequences, which were detected in 11 out of 15 species. Twenty-three haplotypes of flanking sequences and three distinct types of repeats, type I, type II and type III, were found within these 93 sequences. The MS-Align hylogenetic method, newly applied to microsatellite sequences, permitted us to understand the repeat and flanking sequence evolution of Spl-106 locus. The flanking region of locus Spl-106 was highly conserved among the species of genera Acipenser, Huso and Scaphirhynchus, which diverged about 150 million years ago (Mya). The rate of flanking sequence divergence at the microsatellite locus Spl-106 in sturgeons is between 0.011% and 0.079% with an average at 0.028% per million years. Sequence alignment and phylogenetic trees produced by MS-Align showed that both the flanking and repeat regions can cluster the alleles of different species into Pacific and Atlantic lineages. Our results show a synchronous evolutionary pattern between the flanking and repeat regions. Moreover, the coexistence of different repeat types in the same species, even in the same individual, is probably due to two duplication events encompassing the locus Spl-106 that occurred during the divergence of Pacific lineage. The first occured before the diversification of Pacific species (121-96 Mya) and led to repeat types I and II. The second occurred more recently, just before the speciation of A. sinensis and A. dabryanus (69-10 Mya), and led to repeat type III. Sequences in the same species with different repeat types probably corresponds to paralogous loci. This study sheds a new light on the evolutionary mechanisms that shape the complex microsatellite loci involving different repeat types.

  9. Achievement motivation and locus of control of black university students

    Directory of Open Access Journals (Sweden)

    Ronel Erwee

    1986-04-01

    Full Text Available The objective of the study was to research the dimensionality of achievement motivation and locus of control in black university students. The Achievement Motivation Questionnaire (Pottas, Erwee, Boshoff & Lessing, 1980 and the Internal-External Locus of Control Scale (Rotter, 1966 were completed by 251 students. Three locus of control factors were extracted by means of principal factor analysis with varimax rotation, viz. Personal control, Political control, and Control over social relationships. The hypothesis that locus of control is a multi-dimensional construct was accepted. No significant sex differences occurred in the total scores obtained on the questionnaire. However, analyses of the subscales indicated that females seem to be more action-orientated, but believe that they can exert less control over political and world events than males. The hypothesis that locus of control and achievement motivation are two separate but interrelated constructs was supported. OpsommingDie doelwit van die studie was om die dimensionaliteit van swart studente se prestasiemotivering en lokus-van-kontrole na te vors. Die Prestasie-motiveringsvraelys (Pottas, Erwee, Boshoff en Lessing, 1980 en die Interne- Eksterne Lokus van Kontroleskaal (Rotter, 1966 is deur 251 studente voltooi. Drie lokus-van-kontrolefaktore, naamlik Persoonlike kontrole, Politieke kontrole en Kontrole oor interpersoonlike verhoudings, is deur middel van 'n hooffaktorontleding (met varimax-rotasie onttrek. Die hipotese dat lokus-van- kontrole 'n multidimensionele konstruk is, is aanvaar. Geen beduidende geslagsverskille in die totaaltellings op die meetinstrumente het voorgekom nie. Analises van die subskale het egter aangetoon dat die vroue hulself as meer aksie-georienteerd beskou het, maar oortuig was dat hulle nie veel beheer oor politieke en wereldgebeure het nie. Die hipotese dat prestasiemotivering en lokus-van-kontrole twee afsonderlike maar verwante konstrukte is, is aanvaar.

  10. Reframing Student Affairs Leadership: An Analysis of Organizational Frames of Reference and Locus of Control

    Science.gov (United States)

    Tull, Ashley; Freeman, Jerrid P.

    2011-01-01

    Examined in this study were the identified frames of reference and locus of control used by 478 student affairs administrators. Administrator responses were examined to identify frames of reference most commonly used and their preference order. Locus of control most commonly used and the relationship between frames of reference and locus of…

  11. Locus of Control in Offenders and Alleged Offenders with Learning Disabilities

    Science.gov (United States)

    Goodman, Wendy; Leggett, Janice; Garrett, Tanya

    2007-01-01

    Locus of control can be a useful measure of treatment outcome in offenders from the general population. However, there is little information regarding locus of control and offenders with learning disabilities. Existing measures of locus of control use complex language and abstract ideas that may not be accessible to individuals in this group. A…

  12. On the Relation of Locus of Control and L2 Reading and Writing Achievement

    Science.gov (United States)

    Ghonsooly, Behzad; Shirvan, Majid Elahi

    2011-01-01

    Locus of control, a psychological construct, has been the focus of attention in recent decades. Psychologists have discussed the effect of locus of control on achieving life goals in social/psychological interactions. While learning a foreign language involves both social interactions and psychological processes, the role and relation of locus of…

  13. On the Locus Formed by the Maximum Heights of Projectile Motion with Air Resistance

    Science.gov (United States)

    Hernandez-Saldana, H.

    2010-01-01

    We present an analysis on the locus formed by the set of maxima of the trajectories of a projectile launched in a medium with linear drag. Such a place, the locus of apexes, is written in terms of the Lambert "W" function in polar coordinates, confirming the special role played by this function in the problem. To characterize the locus, a study of…

  14. Research Paper Predicting HIV risk using a locus of control-based ...

    African Journals Online (AJOL)

    The study performed correlational and linear regression analyses using statistical software SAS to establish the relationship between locus of control-based factors and HIV risk. Results: The results showed significant correlations between locus of control-based variables and HIV risk. The locus of control-based model ...

  15. DMPD: The Lps locus: genetic regulation of host responses to bacteriallipopolysaccharide. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 10669111 The Lps locus: genetic regulation of host responses to bacteriallipopolysa...ccharide. Qureshi ST, Gros P, Malo D. Inflamm Res. 1999 Dec;48(12):613-20. (.png) (.svg) (.html) (.csml) Show The Lps locus: genetic... regulation of host responses to bacteriallipopolysaccharide. PubmedID 10669111 Title The Lps locus: genetic

  16. Motor activity of centromere-associated protein-E contributes to its localization at the center of the midbody to regulate cytokinetic abscission

    Science.gov (United States)

    Ohashi, Akihiro; Ohori, Momoko; Iwai, Kenichi

    2016-01-01

    Accurate control of cytokinesis is critical for genomic stability to complete high-fidelity transmission of genetic material to the next generation. A number of proteins accumulate in the intercellular bridge (midbody) during cytokinesis, and the dynamics of these proteins are temporally and spatially orchestrated to complete the process. In this study, we demonstrated that localization of centromere-associated protein-E (CENP-E) at the midbody is involved in cytokinetic abscission. The motor activity of CENP-E and the C-terminal midbody localization domain, which includes amino acids 2659–2666 (RYFDNSSL), are involved in the anchoring of CENP-E to the center of the midbody. Furthermore, CENP-E motor activity contributes to the accumulation of protein regulator of cytokinesis 1 (PRC1) in the midbody during cytokinesis. Midbody localization of PRC1 is critical to the antiparallel microtubule structure and recruitment of other midbody-associated proteins. Therefore, CENP-E motor activity appears to play important roles in the organization of these proteins to complete cytokinetic abscission. Our findings will be helpful for understanding how each step of cytokinesis is regulated to complete cytokinetic abscission. PMID:27835888

  17. An investigation on the mediating role of coping strategies on locus of control-- wellbeing relationship.

    Science.gov (United States)

    Thiruchelvi, Arunachalam; Supriya, Mangatvadakkeveetil V

    2012-03-01

    The relationship among coping strategies, locus of control, and workplace wellbeing is examined. The model hypothesizes that coping strategies mediate the relationship between locus of control and work place well being. To test the model, data was collected from 154 software professionals using separate tools to assess coping strategies, locus of control and work place wellbeing. Model fit for the collected data was examined using structural equation modeling technique with the help of AMOS. Results support the view that coping strategies mediate the relationship between locus of control and work place wellbeing. While the path between locus of control and wellbeing is significant, the path between coping distraction and wellbeing is not significant.

  18. Assignment of a locus (GLC3A) for primary congenital glaucoma (Buphthalmos) to 2p21 and evidence for genetic heterogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Sarfarazi, M.; Akarsu, A.N.; Hossain, A. [Univ. of Connecticut Health Center, Farmington, CT (United States)] [and others

    1995-11-20

    Primary congenital glaucoma (GLC3) is an inherited eye disorder that accounts for 0.01-0.04% of total blindness. Although a large number of chromosomal abnormalities have already been reported in patients with congenital glaucoma, the precise location and pathogenesis of this condition remain elusive. By using a group of 17 GLC3 families and a combination of both candidate regional and general positional mapping strategies, we have mapped a locus for GLC3 to the short arm of chromosome 2. Eleven families showed no recombination with 3 tightly linked markers of D2S177 (Z = 9.40), D2S1346 (Z = 8.83), and D2S1348 (Z = 8.90) with a combined haplotype lod score of 11.50. Haplotype and multipoint linkage analyses of 14 DNA markers from 2p indicated that the disease gene is located in the 2p21 region and is flanked by DNA markers D2S1788/D2S1325 ({theta} = 0.03; Z = 5.42) and D2S1356 ({theta} = 0.05; Z = 4.69). Inspection of haplotype and heterogeneity analysis confirmed that 6 families are not linked to the 2p21 region, thus providing the first proof of genetic heterogeneity for this phenotype. We therefore designated the locus on 2p21 GLC3A and positioned it in the overall linkage map of Tel-D2S405-D2S367-(D2S1788/D2S1325)-[(GLC 3A,D2S177)/(D2S1346/D2S1348)]-D2S1356-D2S119-D2S1761-D2S1248-D2S1352-D2S406-D2S441-Cen. Of the seven genes mapping to the 2p21 region, CAD, CALM2, and LHCGR are centromeric to D2S119 and can be excluded as a candidate for GLC3A, but mutations in PRK-R, TIK, SOS1, or SPTBN1 may still be accountable for this phenotype. As human 2p21 shows homology with mouse chromosomes 11 and 17, the homolog of GLC3A is expected to reside on one of these two chromosomes. 36 refs., 3 figs., 5 tabs.

  19. Academic anxiety, locus of control, and achievement in medical school.

    Science.gov (United States)

    Grover, P L; Smith, D U

    1981-09-01

    Programs designed to assist medical students in academic difficulty typically fail to consider the importance of such factors as academic anxiety and the individual's mechanisms for coping with stress. The authors have addressed this issue by examining relationships among prior achievement, academic anxiety, locus of control, and performance in the first year of medical school. Academic anxiety not only was found to be significantly related to first year performance, but also, when combined with a measure of prior achievement, resulted in a significant increase in prediction. Additional evidence is presented which suggests that the relationship between academic anxiety and achievement may be curvilinear. Locus of control was found to correlate significantly with academic anxiety and tended to shift in a direction of greater externality during the first year of medical school. Findings are discussed within the framework of existing psychological research, and implications are presented for medical admissions, curricula, and counseling.

  20. The validity of locus of control dimensions for Chicano populations.

    Science.gov (United States)

    Garza, R T; Widlak, F W

    1977-12-01

    The multidimensional locus of control literature supported the tenability of five factorial dimensions: a) luck/fate, b) leadership/success, c) academics, d) politics, and e) respect. Contending that the contradictory locus of control findings involving Chicano populations may be due to methodological inadequacies, the purpose of the present study was to empirically determine the appropriateness of the five categories for comparing Chicano and Anglo populations. This was done by factor analyzing the responses of 203 Anglo and 244 Chicano undergraduates to Rotter's (1966) 1-E scale separately, and then comparing the corresponding factor pairs by using Cliff's (1966) congruence procedure. The luck/fate and leadership/success factors show substantial invariance across the two samples, whereas the cultural equivalence of the remaining three factors is somewhat questionable. The findings are discussed in relation to current knowledge of cross-cultural differences between Anglo and Chicano populations.

  1. The Molecular Revolution in Cutaneous Biology: EDC and Locus Control.

    Science.gov (United States)

    Oh, Inez Y; de Guzman Strong, Cristina

    2017-05-01

    The epidermal differentiation complex (EDC) locus consists of a cluster of genes important for the terminal differentiation of the epidermis. While early studies identified the functional importance of individual EDC genes, the recognition of the EDC genes as a cluster with its shared biology, homology, and physical linkage was pivotal to later studies that investigated the transcriptional regulation of the locus. Evolutionary conservation of the EDC and the transcriptional activation during epidermal differentiation suggested a cis-regulatory mechanism via conserved noncoding elements or enhancers. This line of pursuit led to the identification of CNE 923, an epidermal-specific enhancer that was found to mediate chromatin remodeling of the EDC in an AP-1 dependent manner. These genomic studies, as well as the advent of high-throughput sequencing and genome engineering techniques, have paved the way for future investigation into enhancer-mediated regulatory networks in cutaneous biology. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Locus Solus: The New York School Poets’ Missing Manifesto

    Directory of Open Access Journals (Sweden)

    Evelyn Austin

    2014-07-01

    Full Text Available Although the New York School of poetry is at its core a literary coterie, critics have been hesitant to consider the New York School an organized group. An exploration of Locus Solus, a literary journal edited by John Ashbery, Kenneth Koch, Frank O’Hara, Harry Mathews, and James Schuyler, however, reveals that the poets were most definitely concerned with presenting themselves as a joint force in American poetry. Through close reading and archival research, I untangle the poets’ instrumentalization of Locus Solus as an elaborate manifesto, exposing how the first three volumes were used to present the New York School poets and poetics, trace a poetic lineage, and put forward a succeeding generation.

  3. Analysis of the ABCA4 genomic locus in Stargardt disease.

    Science.gov (United States)

    Zernant, Jana; Xie, Yajing Angela; Ayuso, Carmen; Riveiro-Alvarez, Rosa; Lopez-Martinez, Miguel-Angel; Simonelli, Francesca; Testa, Francesco; Gorin, Michael B; Strom, Samuel P; Bertelsen, Mette; Rosenberg, Thomas; Boone, Philip M; Yuan, Bo; Ayyagari, Radha; Nagy, Peter L; Tsang, Stephen H; Gouras, Peter; Collison, Frederick T; Lupski, James R; Fishman, Gerald A; Allikmets, Rando

    2014-12-20

    Autosomal recessive Stargardt disease (STGD1, MIM 248200) is caused by mutations in the ABCA4 gene. Complete sequencing of ABCA4 in STGD patients identifies compound heterozygous or homozygous disease-associated alleles in 65-70% of patients and only one mutation in 15-20% of patients. This study was designed to find the missing disease-causing ABCA4 variation by a combination of next-generation sequencing (NGS), array-Comparative Genome Hybridization (aCGH) screening, familial segregation and in silico analyses. The entire 140 kb ABCA4 genomic locus was sequenced in 114 STGD patients with one known ABCA4 exonic mutation revealing, on average, 200 intronic variants per sample. Filtering of these data resulted in 141 candidates for new mutations. Two variants were detected in four samples, two in three samples, and 20 variants in two samples, the remaining 117 new variants were detected only once. Multimodal analysis suggested 12 new likely pathogenic intronic ABCA4 variants, some of which were specific to (isolated) ethnic groups. No copy number variation (large deletions and insertions) was detected in any patient suggesting that it is a very rare event in the ABCA4 locus. Many variants were excluded since they were not conserved in non-human primates, were frequent in African populations and, therefore, represented ancestral, and not disease-associated, variants. The sequence variability in the ABCA4 locus is extensive and the non-coding sequences do not harbor frequent mutations in STGD patients of European-American descent. Defining disease-associated alleles in the ABCA4 locus requires exceptionally well characterized large cohorts and extensive analyses by a combination of various approaches. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. An Analysis of Leader Locus of Control and Influence Behaviors.

    Science.gov (United States)

    1983-05-01

    Social desirability response .j• bias: Three alternative models . Academy of Management Journal, 1983, 26. Graen, C., & Schiemann, W. Leader -member...among managers . Organizational Behavior and Human Performance, 1973, 1 184-200. Durand, D.E., & Nord, W.R. Perceived leader behavior as a function of...AD-A129 100 A N A NALYSIS OF LEAQER LOCUS OF CONTROL AND INFLUENCE BEHAVIORS U) NEBRASKA UNIV LINCOLN DEPT OF MANAGEMENT UNLSIID A L JOHNSON ET AL

  5. Locus-specific view of flax domestication history

    OpenAIRE

    Fu, Yong-Bi; Diederichsen, Axel; Allaby, Robin G.

    2012-01-01

    Crop domestication has been inferred genetically from neutral markers and increasingly from specific domestication-associated loci. However, some crops are utilized for multiple purposes that may or may not be reflected in a single domestication-associated locus. One such example is cultivated flax (Linum usitatissimum L.), the earliest oil and fiber crop, for which domestication history remains poorly understood. Oil composition of cultivated flax and pale flax (L. bienne Mill.) indicates th...

  6. Surfeit locus gene homologs are widely distributed in invertebrate genomes.

    OpenAIRE

    Armes, N.; Fried, M.

    1996-01-01

    The mouse Surfeit locus contains six sequence-unrelated genes (Surf-1 to -6) arranged in the tightest gene cluster so far described for mammals. The organization and juxtaposition of five of the Surfeit genes (Surf-1 to -5) are conserved between mammals and birds, and this may reflect a functional or regulatory requirement for the gene clustering. We have undertaken an evolutionary study to determine whether the Surfeit genes are conserved and clustered in invertebrate genomes. Drosophila mel...

  7. Characterization of a Multipeptide Lantibiotic Locus in Streptococcus pneumoniae

    Directory of Open Access Journals (Sweden)

    Natalie Maricic

    2016-01-01

    Full Text Available Bacterial communities are established through a combination of cooperative and antagonistic interactions between the inhabitants. Competitive interactions often involve the production of antimicrobial substances, including bacteriocins, which are small antimicrobial peptides that target other community members. Despite the nearly ubiquitous presence of bacteriocin-encoding loci, inhibitory activity has been attributed to only a small fraction of gene clusters. In this study, we characterized a novel locus (the pld locus in the pathogen Streptococcus pneumoniae that drives the production of a bacteriocin called pneumolancidin, which has broad antimicrobial activity. The locus encodes an unusual tandem array of four inhibitory peptides, three of which are absolutely required for antibacterial activity. The three peptide sequences are similar but appear to play distinct roles in regulation and inhibition. A modification enzyme typically found in loci encoding a class of highly modified bacteriocins called lantibiotics was required for inhibitory activity. The production of pneumolancidin is controlled by a two-component regulatory system that is activated by the accumulation of modified peptides. The locus is located on a mobile element that has been found in many pneumococcal lineages, although not all elements carry the pld genes. Intriguingly, a minimal region containing only the genes required for pneumolancidin immunity was found in several Streptococcus mitis strains. The pneumolancidin-producing strain can inhibit nearly all pneumococci tested to date and provided a competitive advantage in vivo. These peptides not only represent a unique strategy for bacterial competition but also are an important resource to guide the development of new antimicrobials.

  8. The Effects of Locus of Control and Task Difficulty on Procrastination.

    Science.gov (United States)

    Janssen, Tracy; Carton, John S

    1999-12-01

    The authors investigated the effects of locus of control expectancies and task difficulty on procrastination. Forty-two college students were administered an academic locus of control scale and a task that was similar to a typical college homework assignment. The students were randomly assigned to 1 of 2 task difficulty levels. Although none of the results involving task difficulty was significant, several results involving locus of control were significant. Specifically, analyses revealed that students with internal locus of control expectancies tended to begin working on the assignment sooner than students with external locus of control expectancies. In addition, students with internal locus of control completed and returned the assignment sooner than students with external locus of control. The results are discussed within the context of J. B. Rotter's (1966, 1975, 1982) social learning theory.

  9. Population genetics of the HRAS1 minisatellite locus

    Energy Technology Data Exchange (ETDEWEB)

    Devlin, B.; Risch, N. (Yale Univ., New Haven, CT (United States)); Krontiris, T. (Tufts Univ., Boston, MA (United States) New England Medical Center Hospital, Boston, MA (United States))

    1993-12-01

    Several years ago it was reported that rare HRAS1 VNTR alleles occurred more frequently in US Caucasian cancer patients than in unaffected controls. Such an association, in theory, could be caused by undetected population heterogeneity. Also, in a study clearly relevant to this issue, it was recently reported that significant deviations from Hardy-Weinberg equilibrium exist at this locus in a sample of US Caucasians. These considerations motivate population genetic analysis of the HRAS1 locus. From published studies of the HRAS1 VNTR locus, which classified alleles into types, the authors found only small differences in the allele frequency distributions of samples from various European nations, although there were larger differences among ethnic groups (African American, Caucasian, and Oriental). In an analysis of variation of rare-allele frequencies among samples from four European nations, most of the variance was attributable to molecular methodology, and very little of the variance was accounted for by nationality. In addition, the authors showed that mixture of European subpopulations should result in only minor deviations from expected genotype proportions in a Caucasian database and demonstrated that there was no significant deviation from Hardy-Weinberg equilibrium in the HRAS1 data. 35 refs., 4 tabs.

  10. Genomic characterization of the Atlantic cod sex-locus.

    Science.gov (United States)

    Star, Bastiaan; Tørresen, Ole K; Nederbragt, Alexander J; Jakobsen, Kjetill S; Pampoulie, Christophe; Jentoft, Sissel

    2016-08-08

    A variety of sex determination mechanisms can be observed in evolutionary divergent teleosts. Sex determination is genetic in Atlantic cod (Gadus morhua), however the genomic location or size of its sex-locus is unknown. Here, we characterize the sex-locus of Atlantic cod using whole genome sequence (WGS) data of 227 wild-caught specimens. Analyzing more than 55 million polymorphic loci, we identify 166 loci that are associated with sex. These loci are located in six distinct regions on five different linkage groups (LG) in the genome. The largest of these regions, an approximately 55 Kb region on LG11, contains the majority of genotypes that segregate closely according to a XX-XY system. Genotypes in this region can be used genetically determine sex, whereas those in the other regions are inconsistently sex-linked. The identified region on LG11 and its surrounding genes have no clear sequence homology with genes or regulatory elements associated with sex-determination or differentiation in other species. The functionality of this sex-locus therefore remains unknown. The WGS strategy used here proved adequate for detecting the small regions associated with sex in this species. Our results highlight the evolutionary flexibility in genomic architecture underlying teleost sex-determination and allow practical applications to genetically sex Atlantic cod.

  11. Relationship between nursing students' epistemological beliefs and locus of control.

    Science.gov (United States)

    Yilmaz, Aylin; Kaya, Hülya

    2010-10-01

    The aim of this study was to determine the relationship between nursing students' epistemologic beliefs and locus of control, and the research was conducted at Istanbul University Florence Nightingale School of Nursing with 350 nursing students. Data were collected using the Turkish version of the Epistemological beliefs questionnaire and Rotter's Internal-External Locus of Control Scale. In the data analysis number, percentage, mean, correlation analysis, one-way analysis of variance and Tukey HSD test were used. The findings as whole indicated that nursing students' epistemological beliefs that "The Belief of Learning Depends on Effort (Effort)" showed a greater degree of development than their beliefs about the two other dimensions as named "The Belief of Learning Depends on Ability (Ability)" and "The Belief That There is Only One Unchanging Truth (Unchanging Truth)" in this study, while their belief that there is Unchanging Truth was not developed when compared to the other two. There was a positive correlation between nursing students locus of control and Effort and Ability dimensions, but a significant correlation was not found with Unchanging Truth dimension. This researcher suggests that research should be carried out to determine nursing students' epistemological beliefs and the factors influencing them in an environment to promote the development of these beliefs, and thus the research can be used to learn about the development of the epistemological beliefs. Copyright © 2010 Elsevier Ltd. All rights reserved.

  12. Evidence for genetic heterogeneity in tuberous sclerosis: One locus on chromosome 9 and at least one locus elsewhere

    Energy Technology Data Exchange (ETDEWEB)

    Northrup, H.; Rodriguez, E. Jr. (Univ. of Texas Medical School, Houston, TX (United States)); Herman, G.E.; Lewis, R.A. (Baylor College of Medicine, Houston, TX (United States)); Kwiatkowski, D.J. (Brigham and Womens' s Hospital, Boston, MA (United States)); Roach, E.S. (Univ. of Texas Southerwestern Medical School, Dallas, TX (United States)); Dobyns, W.B. (Riley Hospital, Indianapolis, IN (United States)); Daiger, S.P.; Blanton, S.H. (Univ. of Texas Health Science Center, Houston, TX (United States))

    1992-10-01

    Linkage of tuberous sclerosis complex (TSC), an autosomal dominant disorder, to markers on chromosome 9 was reported first in 1987. This assignment was confirmed by an international collaborative study that suggested more than one locus may be responsible for the phenotype. The authors studied 14 multigenerational TSC families (13 previously unreported) with markers for nine loci in the linked region of chromosome 9q32-q34. Results confirm the previous reports that the genetic locus in one-third to one-half of families maps to chromosome 9. Comparison of clinical findings in the chromosome 9-linked families with those in the chromosome 9-unlinked families reveals only a higher incidence of ungual fibromata in the chromosome 9-linked families. 38 refs., 6 figs., 4 tabs.

  13. Multiplication of Chromosome 17 Centromere Is Associated with Prognosis in Patients with Invasive Breast Cancers Exhibiting Normal HER2 and TOP2A Status.

    Science.gov (United States)

    Kim, Aeri; Shin, Hyung Chan; Bae, Young Kyung; Kim, Min Kyoung; Kang, Su Hwan; Lee, Soo Jung; Lee, Eun Hee

    2012-03-01

    This study aimed to investigate the clinical significance of chromosome 17 centromere (CEP17) multiplication (increased copy number of CEP17) related to human epidermal growth factor receptor 2 (HER2) and topoisomerase II alpha (TOP2A) status in patients with invasive breast cancer. We constructed tissue microarrays using 594 invasive breast cancer samples and performed single-color silver-enhanced in situ hybridization (SISH) assay for HER2, TOP2A, and CEP17 to assess for copy number aberrations. The association of CEP17 multiplication with patient survival was analyzed according to HER2 and TOP2A status. Among 567 informative cases, HER2 amplification was noted in 22.8%, TOP2A amplification in 8.3% and TOP2A deletion in 11.1%. CEP17 multiplication was identified in 33.2% and was significantly associated with worse overall survival (OS) (p=0.02) and disease-free survival (DFS) (p=0.02). CEP17 multiplication correlated with patient survival in patients with normal TOP2A or non-amplified HER2 status, but the prognostic significance was lost in those with altered TOP2A or amplified HER2. On multivariate analyses, CEP17 multiplication was an independent prognostic factor for poorer OS (p=0.02) and DFS (p=0.01) in patients with normal TOP2A and non-amplified HER2. CEP17 multiplication was identified as a promising prognostic marker in patients with invasive breast cancer exhibiting either non-amplified HER2 or normal TOP2A status.

  14. Locus de Controle e escolha do método anticoncepcional Locus de Control y método anticonceptivo elegido Locus of Control and choice of contraceptive method

    Directory of Open Access Journals (Sweden)

    Aline Salheb Alves

    2007-06-01

    Full Text Available Objetivou-se avaliar a relação entre o Locus de Controle e o tipo de método contraceptivo escolhido. Foi utilizada a Escala Multidimensional de Locus de Controle de Levenson e entrevistadas 191 mulheres. As usuárias de preservativo masculino apresentaram maior Internalidade do que as usuárias de injetável mensal. Quanto ao locus Externalidade Outros Poderosos, as usuárias de implante apresentavam menor externalidade do que as usuárias de preservativo masculino, laqueadura, injetável trimestral e DIU. Considerando-se o locus Externalidade Acaso, as usuárias de implante apresentaram menores escores do que as mulheres que optaram pela laqueadura, injetável trimestral e DIU. Observou-se ainda, menor Externalidade Acaso entre as usuárias de injetável mensal em relação às mulheres que fizeram opção pelo injetável trimestral.El objetivo es validar la relación entre el Locus de Control y el tipo de método anticonceptivo elegido. Fue usada la Escala Multidimensional de Locus de Control de Levenson. Fueron entrevistadas 191 mujeres. Las usuarias de condón masculino presentaron Internalidad más grande que las usuarias de inyectable mensual. Considerado el Locus Externalidad - Otro poderoso, las usuarias de implante presentaron menor externalidad de que las usuarias de condón masculino, laqueadura, inyectable trimestral y DIU. Considerado el Locus Externalidad - Quizá, las usuarias del implante presentaron menores resultados que las mujeres que eligieron por la laqueadura, inyectable trimestral y DIU. Se observo que las mujeres usuarias de inyectable mensual presentaron menor Externalidad - Quizá que las mujeres usuarias de inyectable trimestral.The purpose was to assess the relationship between locus of control and the contraceptive method chosen. It was used the Levenson's Multidimensional Locus of Control Scale and 191 women was interviewed. Users of male condoms presented greater Internality than the monthly contraceptive

  15. Examining the relationship between health locus of control and God Locus of Health Control: Is God an internal or external source?

    Science.gov (United States)

    Boyd, Joni M; Wilcox, Sara

    2017-11-01

    For many people, the influence of believing in a higher power can elicit powerful effects. This study examined the relationship between God control, health locus of control, and frequency of religious attendance within 838 college students through online surveys. Regression analysis showed that chance and external locus of control and frequency of religious attendance were significant and positive predictors of God Locus of Health Control. The association of powerful others external locus of control and God Locus of Health Control differed by race (stronger in non-Whites than Whites) and somewhat by gender (stronger in women than men). For some people, the role of a supreme being, or God, should be considered when designing programs for improving health behaviors.

  16. Fine mapping a self-fertility locus in perennial ryegrass.

    Science.gov (United States)

    Do Canto, Javier; Studer, Bruno; Frei, Ursula; Lübberstedt, Thomas

    2017-12-15

    A self-fertility locus was fine mapped to a 1.6 cM region on linkage group 5 in a perennial ryegrass population. This locus was the main determinant of pollen self-compatibility. In grasses, self-incompatibility (SI) is characterized by a two-loci gametophytic (S and Z) mechanism acting together in the recognition and inhibition of self-pollen. Mutations affecting the expression of SI have been reported in a few grass species. In perennial ryegrass (Lolium perenne L.), a mutation independent from S and Z, and mapping on linkage group 5 (LG 5), was previously reported to produce self-fertile plants. Here, we describe fine mapping of the self-fertility (SF) gene in a perennial ryegrass population and determine whether there is any effect of other genomic regions on the pollen compatibility. The phenotypic segregation of SF showed a bimodal distribution with one mean at 49% pollen compatibility and the other at 91%. Marker-trait association analysis showed that only markers on LG 5 were significantly associated with the trait. A single gene model explained 82% of the observed variability and no effects of the other regions were detected. Using segregation and linkage analysis, the SF locus was located to a 1.6 cM region on LG 5. The flanking marker sequences were aligned to rice and Brachypodium distachyon reference genomes to estimate the physical distance. We provide markers tightly linked to SF that can be used for introgression of this trait into advanced breeding germplasm. Moreover, our results represent a further step towards the identification of the SF gene in LG 5.

  17. The construction of a normative scale of locus of control

    Directory of Open Access Journals (Sweden)

    Johann M. Schepers

    2005-10-01

    Full Text Available The primary objective of the study was to construct a normative scale of locus of control for use with students and adults. A corollary of the study was to establish the personality, interest and cognitive correlates of locus of control. Conceptually the instrument is based on attribution theory and on social learning theory. The first edition of the Locus of Control Inventory (LCI was applied to 356 first-year university students during 1994. A factor analysis of the 65 items of the inventory yielded three factors. The factors were interpreted as Autonomy, Internal Control and External Control. Three scales, corresponding to the three factors, were constructed, and yielded reliability coefficients of 0,80; 0,77 and 0,81 respectively. Following this the cognitive, interest and personality correlates of the LCI were determined. The implications of the findings are discussed. Opsomming Die hoofdoel van die studie was die konstruksie van ’n normatiewe skaal van lokus van beheer vir gebruik met studente en volwassenes. ’n Newe-doelwit van die studie was om die persoonlikheids-, belangstellings- en kognitiewe korrelate van lokus van beheer te bepaal. Konseptueel is die instrument op attribusieteorie en sosiale-leerteorie gebaseer. Die eerste-uitgawe van die Lokus van Beheervraelys (LvB is op 356 eerstejaaruniversiteitstudente toegepas gedurende 1994. ’n Faktorontleding van die 65 items van die vraelys is gedoen en het drie faktore opgelewer. Die faktore is as Outonomie, Interne Beheer en Eksterne Beheer geïnterpreteer. Voorts is drie skale wat ooreenstem met die drie faktore, gekonstrueer en het betroubaarhede van 0,80; 0,77 en 0,81, onderskeidelik, opgelewer. Vervolgens is die kognitiewe, belangstellings- en persoonlikheidskorrelate van die LvB bepaal. Die implikasies van die bevindinge word bespreek.

  18. Locus of the apices of projectile trajectories under constant drag

    Science.gov (United States)

    Hernández-Saldaña, H.

    2017-11-01

    Using the hodograph method, we present an analytical solution for projectile coplanar motion under constant drag, parametrised by the velocity angle. We find the locus formed by the apices of the projectile trajectories, and discuss its implementation for the motion of a particle on an inclined plane in presence of Coulomb friction. The range and time of flight are obtained numerically, and we find that the optimal launching angle is smaller than in the drag-free case. This is a good example of a problem with constant dissipation of energy that includes curvature; it is appropriate for intermediate courses of mechanics.

  19. [Polymorphism of the DXS1062 locus in a Polish population].

    Science.gov (United States)

    Cybulska, Lidia; Szczerkowska, Zofia

    2004-01-01

    This paper presents the results of a population study of a dinucleotide STR marker DXS1062. Blood samples were obtained from unrelated adult individuals (males and females) living in the northern part of Poland. In the analyzed population, 21 different phenotypes and 9 alleles of the DXS1062 locus were found. The alleles were sequenced and used for the construction of an allelic ladder. The nomenclature in accordance with ISFG guidelines was proposed. The most frequent alleles were 20 and 21. Statistical parameters (PR, PM, PD, PIC) showed that the examined system is useful in forensic medicine.

  20. Rapid Multi-Locus Sequence Typing Using Microfluidic Biochips

    Science.gov (United States)

    2010-05-12

    Chlamydia (manuscript in preparation) and performed pilot studies on Staphylococcus aureus and Streptoccus pneumoniae (Data S4 and Text S2). Another potential...Found at: doi:10.1371/journal.pone.0010595.s009 (0.00 MB TXT) Text S2 mMLST sequencing of S. aureus and S. pneumoniae . Found at: doi:10.1371...provided S. aureus and S. pneumoniae strains. This publication made use of the Bacillus cereus Multi Locus Sequence Typing website (http://pubmlst.org

  1. Measurement of supernatural belief: sex differences and locus of control.

    Science.gov (United States)

    Randall, T M; Desrosiers, M

    1980-10-01

    Although we live in an age dominated by science and technology, there exists an increasingly popular anti-science sentiment. This study describes the development of a scale to assess the degree of personal acceptance of supernatural causality versus acceptance of scientific explanation. In addition to the psychometric data concerning validity and reliability of the scale, data are presented which showed the personality factor of supernaturalism to be independent of orthodox religious attitudes. Results indicated a significantly greater supernatural acceptance for women, and a positive relation of supernaturalism with external locus of control.

  2. Locus of control and its relationship with mental health and adjustment among adolescent females

    Directory of Open Access Journals (Sweden)

    Madhu Jain

    2015-01-01

    Full Text Available Objective: There exists a plethora of researches which have identified the role of Locus of Control in maintaining sound mental health and adjustment. The present study examined the relationship of Locus of Control with Mental Health & overall Adjustment among adolescent females. Method: The participants consisted of 50 adolescent females. Mental Health Battery designed by Singh, Gupta (2000, Rotter′s Locus of Control Scale (1966 & Adjustment Inventory for College Students by Sinha & Singh (1995 were administered. Findings: The findings of the study revealed that adolescent females who possess internal locus of control showed better mental health & overall adjustment pattern which includes home, social, emotional, educational domains and health adjustment domain than those who possess external locus of control. Conclusion: The study highlights the pervasive influence of internal & external locus of control on mental health & adjustment among adolescent females.

  3. The relationship between the perception of own locus of control and aggression of adolescent boys

    OpenAIRE

    Lettie Breet; Chris Myburgh; Marie Poggenpoel

    2010-01-01

    Aggression is increasingly seen in most parts of South African society. Aggressive behaviour of boys in secondary school often results from frustrations caused by perceived high expectations of others regarding the role, locus of control, and personality of boys. Locus of control plays an important role in a person's perception concerning a situation and possible reactions to what is happening, or should be happening. A 56-item questionnaire, based on Rotter's "Locus of control" questionnaire...

  4. The Contribution of Locus of Control to Academic Procrastination in Islamic Education Management Students in Indonesia

    OpenAIRE

    Juliana Batubara

    2017-01-01

    This study aimed to describe the locus of control and academic procrastination, and investigate whether there is significance contributions of locus of control on student academic procrastination. This research was conducted by the Ex post-facto method was used in this study, where the data taken from two set of questionnaires. Proportional Stratified Random Sampling was used. There were 107 students involved this study. The results showed that the locus of control is in average level, meanwh...

  5. Prevalence of Porphyromonas gingivalis Four rag Locus Genotypes in Patients of Orthodontic Gingivitis and Periodontitis

    OpenAIRE

    Liu, Yi; Zhang, Yujie; Wang, Lili; Guo, Yang; Xiao, Shuiqing

    2013-01-01

    Porphyromonas gingivalis is considered as a major etiological agent in periodontal diseases and implied to result in gingival inflammation under orthodontic appliance. rag locus is a pathogenicity island found in Porphyromonas gingivalis. Four rag locus variants are different in pathogenicity of Porphyromonas gingivalis. Moreover, there are different racial and geographic differences in distribution of rag locus genotypes. In this study, we assessed the prevalence of Porphyromonas gingivalis ...

  6. Thorough investigation of a canine autoinflammatory disease (AID confirms one main risk locus and suggests a modifier locus for amyloidosis.

    Directory of Open Access Journals (Sweden)

    Mia Olsson

    Full Text Available Autoinflammatory disease (AID manifests from the dysregulation of the innate immune system and is characterised by systemic and persistent inflammation. Clinical heterogeneity leads to patients presenting with one or a spectrum of phenotypic signs, leading to difficult diagnoses in the absence of a clear genetic cause. We used separate genome-wide SNP analyses to investigate five signs of AID (recurrent fever, arthritis, breed specific secondary dermatitis, otitis and systemic reactive amyloidosis in a canine comparative model, the pure bred Chinese Shar-Pei. Analysis of 255 DNA samples revealed a shared locus on chromosome 13 spanning two peaks of association. A three-marker haplotype based on the most significant SNP (p<2.6×10(-8 from each analysis showed that one haplotypic pair (H13-11 was present in the majority of AID individuals, implicating this as a shared risk factor for all phenotypes. We also noted that a genetic signature (F ST distinguishing the phenotypic extremes of the breed specific Chinese Shar-Pei thick and wrinkled skin, flanked the chromosome 13 AID locus; suggesting that breed development and differentiation has played a parallel role in the genetics of breed fitness. Intriguingly, a potential modifier locus for amyloidosis was revealed on chromosome 14, and an investigation of candidate genes from both this and the chromosome 13 regions revealed significant (p<0.05 renal differential expression in four genes previously implicated in kidney or immune health (AOAH, ELMO1, HAS2 and IL6. These results illustrate that phenotypic heterogeneity need not be a reflection of genetic heterogeneity, and that genetic modifiers of disease could be masked if syndromes were not first considered as individual clinical signs and then as a sum of their component parts.

  7. External locus of control contributes to racial disparities in memory and reasoning training gains in ACTIVE.

    Science.gov (United States)

    Zahodne, Laura B; Meyer, Oanh L; Choi, Eunhee; Thomas, Michael L; Willis, Sherry L; Marsiske, Michael; Gross, Alden L; Rebok, George W; Parisi, Jeanine M

    2015-09-01

    Racial disparities in cognitive outcomes may be partly explained by differences in locus of control. African Americans report more external locus of control than non-Hispanic Whites, and external locus of control is associated with poorer health and cognition. The aims of this study were to compare cognitive training gains between African American and non-Hispanic White participants in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) study and determine whether racial differences in training gains are mediated by locus of control. The sample comprised 2,062 (26% African American) adults aged 65 and older who participated in memory, reasoning, or speed training. Latent growth curve models evaluated predictors of 10-year cognitive trajectories separately by training group. Multiple group modeling examined associations between training gains and locus of control across racial groups. Compared to non-Hispanic Whites, African Americans evidenced less improvement in memory and reasoning performance after training. These effects were partially mediated by locus of control, controlling for age, sex, education, health, depression, testing site, and initial cognitive ability. African Americans reported more external locus of control, which was associated with smaller training gains. External locus of control also had a stronger negative association with reasoning training gain for African Americans than for Whites. No racial difference in training gain was identified for speed training. Future intervention research with African Americans should test whether explicitly targeting external locus of control leads to greater cognitive improvement following cognitive training. (c) 2015 APA, all rights reserved).

  8. Shiftwork Locus of Control, Situational and Behavioural Effects on Sleepiness and Fatigue in Shiftworkers

    National Research Council Canada - National Science Library

    SMITH, Lawrence; TANIGAWA, Takeshi; TAKAHASHI, Masaya; MUTOU, Keiko; TACHIBANA, Naoko; KAGE, Yoshiko; ISO, Hiroyasu

    2005-01-01

    .... Power company shiftworkers completed a questionnaire that measured age/experience, number of dependents, shiftwork locus of control, morningness-eveningness, workload and sleep/health-related behaviours...

  9. Investigation of the 5q33.3 longevity locus and age-related phenotypes

    OpenAIRE

    Nygaard, Marianne; Thinggaard, Mikael; Christensen, Kaare; Christiansen, Lene

    2017-01-01

    A large meta-analysis recently found the 5q33.3 locus to be associated with survival to ≥ 90 years and lower all-cause mortality, thus suggesting it as a third human longevity locus alongside APOE and FOXO3A. The 5q33.3 locus has previously been associated with blood pressure regulation and cardiovascular diseases in middle-aged individuals. However, part of the influence on mortality appears to be independent of cardiovascular phenotypes, and the role of the 5q33.3 locus in longevity and sur...

  10. The Schizosaccharomyces pombe JmjC-protein, Msc1, prevents H2A.Z localization in centromeric and subtelomeric chromatin domains.

    Directory of Open Access Journals (Sweden)

    Luke Buchanan

    2009-11-01

    Full Text Available Eukaryotic genomes are repetitively packaged into chromatin by nucleosomes, however they are regulated by the differences between nucleosomes, which establish various chromatin states. Local chromatin cues direct the inheritance and propagation of chromatin status via self-reinforcing epigenetic mechanisms. Replication-independent histone exchange could potentially perturb chromatin status if histone exchange chaperones, such as Swr1C, loaded histone variants into wrong sites. Here we show that in Schizosaccharomyces pombe, like Saccharomyces cerevisiae, Swr1C is required for loading H2A.Z into specific sites, including the promoters of lowly expressed genes. However S. pombe Swr1C has an extra subunit, Msc1, which is a JumonjiC-domain protein of the Lid/Jarid1 family. Deletion of Msc1 did not disrupt the S. pombe Swr1C or its ability to bind and load H2A.Z into euchromatin, however H2A.Z was ectopically found in the inner centromere and in subtelomeric chromatin. Normally this subtelomeric region not only lacks H2A.Z but also shows uniformly lower levels of H3K4me2, H4K5, and K12 acetylation than euchromatin and disproportionately contains the most lowly expressed genes during vegetative growth, including many meiotic-specific genes. Genes within and adjacent to subtelomeric chromatin become overexpressed in the absence of either Msc1, Swr1, or paradoxically H2A.Z itself. We also show that H2A.Z is N-terminally acetylated before, and lysine acetylated after, loading into chromatin and that it physically associates with the Nap1 histone chaperone. However, we find a negative correlation between the genomic distributions of H2A.Z and Nap1/Hrp1/Hrp3, suggesting that the Nap1 chaperones remove H2A.Z from chromatin. These data describe H2A.Z action in S. pombe and identify a new mode of chromatin surveillance and maintenance based on negative regulation of histone variant misincorporation.

  11. Meiosis-specific cohesin component, Stag3 is essential for maintaining centromere chromatid cohesion, and required for DNA repair and synapsis between homologous chromosomes.

    Science.gov (United States)

    Hopkins, Jessica; Hwang, Grace; Jacob, Justin; Sapp, Nicklas; Bedigian, Rick; Oka, Kazuhiro; Overbeek, Paul; Murray, Steve; Jordan, Philip W

    2014-07-01

    Cohesins are important for chromosome structure and chromosome segregation during mitosis and meiosis. Cohesins are composed of two structural maintenance of chromosomes (SMC1-SMC3) proteins that form a V-shaped heterodimer structure, which is bridged by a α-kleisin protein and a stromal antigen (STAG) protein. Previous studies in mouse have shown that there is one SMC1 protein (SMC1β), two α-kleisins (RAD21L and REC8) and one STAG protein (STAG3) that are meiosis-specific. During meiosis, homologous chromosomes must recombine with one another in the context of a tripartite structure known as the synaptonemal complex (SC). From interaction studies, it has been shown that there are at least four meiosis-specific forms of cohesin, which together with the mitotic cohesin complex, are lateral components of the SC. STAG3 is the only meiosis-specific subunit that is represented within all four meiosis-specific cohesin complexes. In Stag3 mutant germ cells, the protein level of other meiosis-specific cohesin subunits (SMC1β, RAD21L and REC8) is reduced, and their localization to chromosome axes is disrupted. In contrast, the mitotic cohesin complex remains intact and localizes robustly to the meiotic chromosome axes. The instability of meiosis-specific cohesins observed in Stag3 mutants results in aberrant DNA repair processes, and disruption of synapsis between homologous chromosomes. Furthermore, mutation of Stag3 results in perturbation of pericentromeric heterochromatin clustering, and disruption of centromere cohesion between sister chromatids during meiotic prophase. These defects result in early prophase I arrest and apoptosis in both male and female germ cells. The meiotic defects observed in Stag3 mutants are more severe when compared to single mutants for Smc1β, Rec8 and Rad21l, however they are not as severe as the Rec8, Rad21l double mutants. Taken together, our study demonstrates that STAG3 is required for the stability of all meiosis-specific cohesin

  12. [Locus of control in girls with anorexia readiness syndrome].

    Science.gov (United States)

    Jaros, Katarzyna; Oszwa, Urszula

    2014-01-01

    The aim of the research was to indicate whether there are differences between locus of control (LOC) in girls with anorexia readiness syndrome (ARS) and without this syndrome. There was also a question about the relationship between LOC and the tendency to respond in incorrect attitudes towards food, eating and their bodies under stress. The sample consisted of girls aged 13-18 years randomly selected from five public Polish middle and high schools. Tools: 1) Eating Attitudes Questionnaire (EAQ) by B. Ziółkowska; 2) Locus of Control Questionnaire (LOCQ) by G. Krasowicz, A. Kurzyp-Wojnarska, to assess LOC of the subjects. The criterion group (N=23) was formed by girls who received high score in EAQ (signs of ARS) in the first stage of research (N=189). The control group (N = 23) were girls who received a low score in EAQ (no signs of ARS). Subjects with ARS were characterized by more external LOC than girls without any signs of this syndrome (t = -2.898; p < 0.01). The results did not confirm the hypothesis about the relationship between LOC and the tendency to respond by abnormal attitude to eating and own body in difficult situations in both groups. In pathogenesis of ARS where anorexic behaviors can become a way to a regain lost control, LOC may play a role as a mediating variable rather than a direct determinant of this syndrome.

  13. Genetic polymorphism at the CLOCK gene locus and major depression.

    Science.gov (United States)

    Desan, P H; Oren, D A; Malison, R; Price, L H; Rosenbaum, J; Smoller, J; Charney, D S; Gelernter, J

    2000-06-12

    Genetic analysis in both mouse and Drosophila has indicated that the product of the CLOCK gene is an essential component of a circadian rhythm timing system. A single nucleotide polymorphism (SNP), T3111C, in the 3' flanking region of the human CLOCK gene has been identified. Homozygotes or heterozygotes for the 3111C allele have been reported to have higher mean scores on a measure of evening preference for activity (vs. morning preference) than subjects homozygous for the 3111T allele. Since major depression is hypothesized to be closely linked to circadian rhythms, we explored whether this polymorphism might be related to susceptibility to major depression. We also ascertained allele frequency in an African-American control population, to begin to evaluate population variation at this locus. CLOCK T3111C allele frequencies were determined in 280 European American (EA) subjects, 143 with a history of major depression and 137 screened controls, and in 58 African American (AA) screened control subjects, using a polymerase chain reaction (PCR) - restriction fragment length polymorphism (RFLP) method. There was no significant difference between EA depressed and control subjects in allele frequency. There was a significant difference in allele frequency between EA and AA subjects, demonstrating a potential for population stratification. In none of these groups were significant deviations from Hardy-Weinberg equilibrium found. The present data do not support an association between CLOCK gene alleles at the T3111C locus and major depression.

  14. The Locus analytical framework for indoor localization and tracking applications

    Science.gov (United States)

    Segou, Olga E.; Thomopoulos, Stelios C. A.

    2015-05-01

    Obtaining location information can be of paramount importance in the context of pervasive and context-aware computing applications. Many systems have been proposed to date, e.g. GPS that has been proven to offer satisfying results in outdoor areas. The increased effect of large and small scale fading in indoor environments, however, makes localization a challenge. This is particularly reflected in the multitude of different systems that have been proposed in the context of indoor localization (e.g. RADAR, Cricket etc). The performance of such systems is often validated on vastly different test beds and conditions, making performance comparisons difficult and often irrelevant. The Locus analytical framework incorporates algorithms from multiple disciplines such as channel modeling, non-uniform random number generation, computational geometry, localization, tracking and probabilistic modeling etc. in order to provide: (a) fast and accurate signal propagation simulation, (b) fast experimentation with localization and tracking algorithms and (c) an in-depth analysis methodology for estimating the performance limits of any Received Signal Strength localization system. Simulation results for the well-known Fingerprinting and Trilateration algorithms are herein presented and validated with experimental data collected in real conditions using IEEE 802.15.4 ZigBee modules. The analysis shows that the Locus framework accurately predicts the underlying distribution of the localization error and produces further estimates of the system's performance limitations (in a best-case/worst-case scenario basis).

  15. Self-regulated alternative splicing at the AHNAK locus.

    Science.gov (United States)

    de Morrée, Antoine; Droog, Marjolein; Grand Moursel, Laure; Bisschop, Ilona J M; Impagliazzo, Antonietta; Frants, Rune R; Klooster, Rinse; van der Maarel, Silvère M

    2012-01-01

    AHNAK is a 700-kDa protein involved in cytoarchitecture and calcium signaling. It is secondarily reduced in muscle of dysferlinopathy patients and accumulates in muscle of calpainopathy patients, both affected by a muscular dystrophy. AHNAK directly interacts with dysferlin. This interaction is lost on cleavage of AHNAK by the protease calpain 3, explaining the molecular observations in patients. Currently, little is known of AHNAK regulation. We describe the self-regulation of multiple mRNA transcripts emanating from the AHNAK locus in muscle cells. We show that the AHNAK gene consists of a 17-kb exon flanked by multiple small exons. This genetic structure is shared by AHNAK2 and Periaxin, which share a common ancestor. Two major AHNAK transcripts are differentially expressed during muscle differentiation that encode for a small (17-kDa) and a large (700-kDa) protein isoform. These proteins interact in the cytoplasm, but the small AHNAK is also present in the nucleus. During muscle differentiation the small AHNAK is strongly increased, thereby establishing a positive feedback loop to regulate mRNA splicing of its own locus. A small 17-kDa isoform of Periaxin similarly traffics between the cytoplasm and the nucleus to regulate mRNA splicing. Thus, AHNAK constitutes a novel mechanism in post-transcriptional control of gene expression.

  16. Allelism of Genes in the Ml-a locus

    DEFF Research Database (Denmark)

    Giese, Nanna Henriette; Jensen, Hans Peter; Jørgensen, Jørgen Helms

    1980-01-01

    Seven barley lines or varieties, each with a different gene at the Ml-a locus for resistance to Erysiphe graminis were intercrossed. Progeny testing of the F2s using two different fungal isolates per cross provided evidence that there are two or more loci in the Ml-a region. Apparent recombinants...... were also screened for recombination between the Hor1 and Hor2 loci which are situated either side of the Ml-a locus. The cross between Ricardo and Iso42R (Rupee) yielded one possible recombinant, with Ml-a3 and Ml-a(Rul) in the coupling phase; other recombinants had wild-type genes in the coupling...... phase. Iso20R, derived from Hordeum spontaneum 'H204', carrying Ml-a6, had an additional gene, in close coupling with Ml-a6, tentatively named Ml-aSp2 or Reglv, causing an intermediate infection type with isolate EmA30. It is suggested that Ml-a(Ar) in Emir and Ml-a(Rul), shown to differ from other Ml-a...

  17. Variation in retinal degeneration phenotype inherited at the prcd locus.

    Science.gov (United States)

    Aguirre, G D; Acland, G M

    1988-05-01

    Progressive rod-cone degeneration (prcd) is a recessively inherited visual cell disease. Neither the genetic abnormality nor the corresponding biochemical defect have yet been identified. Unique abnormalities of visual cell structure, function and renewal, however, characterize the disease phenotype and act as a marker for the prcd gene. The disease was first described in miniature poodle dogs (MP) but broadly similar retinal degenerations have been recognized, clinically, in other breeds. Crossbreeding experiments with prcd-affected MP and retinal degenerate English (ECS) and American (ACS) cocker spaniels now demonstrate that all the progeny are affected with a retinal degeneration indistinguishable from prcd in the MP. This indicates that the gene mutation in each breed is at the same (prcd) locus. In purebred prcd-affected ECS (prcd-ECS), however, the disease phenotype consistently differs from that in prcd-MP in its rate of progression and in the topographical distribution of disease within the retina. Ultrastructural variation in disease expression are also recognizable between the two phenotypes. These differences in disease phenotype may be ascribable to different genetic backgrounds in the two breeds, reflecting the effect of modifying genes, or may indicate separate, allelic, mutations at the same locus.

  18. LOCUS: immunizing medical students against the loss of professional values.

    Science.gov (United States)

    Carufel-Wert, Donald A; Younkin, Sharon; Foertsch, Julie; Eisenberg, Todd; Haq, Cynthia L; Crouse, Byron J; Frey Iii, John J

    2007-05-01

    The Leadership Opportunities with Communities, the Underserved, and Special populations (LOCUS) program at the University of Wisconsin School of Medicine and Public Health is a longitudinal, extracurricular experience for medical students who wish to develop leadership skills and expand their involvement in community health activities during medical school. The program consists of a core curriculum delivered through retreats, workshops, and seminars; a mentor relationship with a physician who is engaged in community health services; and a community service project. On-line surveys and interviews with current and past participants as well as direct observations were used to evaluate the effects of the program on participants. Participants indicated that the program was worthwhile, relevant, and effective in building a community of like-minded peers and physician role models. Participants also reported that the program sustained their interest in and commitment to community service and allowed them to cultivate new skills during medical school. The curriculum and structure of the LOCUS program offers a successful method for helping medical students learn important leadership skills and maintain an altruistic commitment to service.

  19. Are there gender differences in locus of control specific to alcohol dependence?

    Science.gov (United States)

    McPherson, Andrew; Martin, Colin R

    2017-01-01

    To investigate gender differences in locus of control in an alcohol-dependent population. Locus of control helps to explain behaviour in terms of internal (the individual is responsible) or external (outside forces, such as significant other people or chance, are responsible) elements. Past research on gender differences in locus of control in relation to alcohol dependence has shown mixed results. There is a need then to examine gender and locus of control in relation to alcohol dependence to ascertain the veracity of any locus of control differences as a function of gender. The Multidimensional Health Locus of Control form-C was administered to clients from alcohol dependence treatment centres in the West of Scotland. Independent t-tests were carried out to assess gender differences in alcohol dependence severity and internal/external aspects of locus of control. One hundred and eighty-eight (53% females) participants were recruited from a variety of alcohol dependence treatment centres. The majority of participants (72%) came from Alcoholics Anonymous groups. Women revealed a greater internal locus of control compared with men. Women also had a greater 'significant others' locus of control score than men. Men were more reliant on 'chance' and 'doctors' than women. All these trends were not, however, statistically significant. Gender differences in relation to locus of control and alcohol dependence from past studies are ambiguous. This study also found no clear statistically significant differences in locus of control orientation as a function of gender. This article helps nurses to contextualise health behaviours as a result of internal or external forces. It also helps nursing staff to better understand alcohol dependence treatment in relation to self-efficacy and control. Moreover, it highlights an important concept in health education theory. © 2016 John Wiley & Sons Ltd.

  20. Secondary evolution of a self-incompatibility locus in the Brassicaceae genus Leavenworthia.

    Directory of Open Access Journals (Sweden)

    Sier-Ching Chantha

    Full Text Available Self-incompatibility (SI is the flowering plant reproductive system in which self pollen tube growth is inhibited, thereby preventing self-fertilization. SI has evolved independently in several different flowering plant lineages. In all Brassicaceae species in which the molecular basis of SI has been investigated in detail, the product of the S-locus receptor kinase (SRK gene functions as receptor in the initial step of the self pollen-rejection pathway, while that of the S-locus cysteine-rich (SCR gene functions as ligand. Here we examine the hypothesis that the S locus in the Brassicaceae genus Leavenworthia is paralogous with the S locus previously characterized in other members of the family. We also test the hypothesis that self-compatibility in this group is based on disruption of the pollen ligand-producing gene. Sequence analysis of the S-locus genes in Leavenworthia, phylogeny of S alleles, gene expression patterns, and comparative genomics analyses provide support for both hypotheses. Of special interest are two genes located in a non-S locus genomic region of Arabidopsis lyrata that exhibit domain structures, sequences, and phylogenetic histories similar to those of the S-locus genes in Leavenworthia, and that also share synteny with these genes. These A. lyrata genes resemble those comprising the A. lyrata S locus, but they do not function in self-recognition. Moreover, they appear to belong to a lineage that diverged from the ancestral Brassicaceae S-locus genes before allelic diversification at the S locus. We hypothesize that there has been neo-functionalization of these S-locus-like genes in the Leavenworthia lineage, resulting in evolution of a separate ligand-receptor system of SI. Our results also provide support for theoretical models that predict that the least constrained pathway to the evolution of self-compatibility is one involving loss of pollen gene function.

  1. Genome-wide association study identifies a single major locus contributing to survival into old age; the APOE locus revisited

    DEFF Research Database (Denmark)

    Deelen, Joris; Beekman, Marian; Uh, Hae-Won

    2011-01-01

    (LLS) and 1670 younger population controls. The strongest candidate SNPs from this GWAS have been analyzed in a meta-analysis of nonagenarian cases from the Rotterdam Study, Leiden 85-plus study and Danish 1905 cohort. Only one of the 62 prioritized SNPs from the GWAS analysis (P ... genome-wide significance with survival into old age in the meta-analysis of 4149 nonagenarian cases and 7582 younger controls (OR = 0.71 (95% CI 0.65-0.77), P = 3.39 x 10(-17) ). This SNP, rs2075650, is located in TOMM40 at chromosome 19q13.32 close to the apolipoprotein E (APOE) gene. Although...... of the nonagenarian cases from the LLS and their partners. In addition, we observed a novel association between this locus and serum levels of IGF-1 in females (P = 0.005). In conclusion, the major locus determining familial longevity up to high age as detected by GWAS was marked by rs2075650, which tags...

  2. The fester locus in Botryllus schlosseri experiences selection

    Directory of Open Access Journals (Sweden)

    Nydam Marie L

    2012-12-01

    Full Text Available Abstract Background Allorecognition, the ability of an organism to distinguish self from non-self, occurs throughout the entire tree of life. Despite the prevalence and importance of allorecognition systems, the genetic basis of allorecognition has rarely been characterized outside the well-known MHC (Major Histocompatibility Complex in vertebrates and SI (Self-Incompatibility in plants. Where loci have been identified, their evolutionary history is an open question. We have previously identified the genes involved in self/non-self recognition in the colonial ascidian Botryllus schlosseri, and we can now begin to investigate their evolution. In B. schlosseri, colonies sharing 1 or more alleles of a gene called FuHC (Fusion Histocompatibility will fuse. Protein products of a locus called fester, located ~300 kb from FuHC, have been shown to play multiple roles in the histocompatibility reaction, as activating and/or inhibitory receptors. We test whether the proteins encoded by this locus are evolving neutrally or are experiencing balancing, directional, or purifying selection. Results Nearly all of the variation in the fester locus resides within populations. The 13 housekeeping genes (12 nuclear genes and mitochondrial cytochrome oxidase I have substantially more structure among populations within groups and among groups than fester. All polymorphism statistics (Tajima's D, Fu and Li's D* and F* are significantly negative for the East Coast A-type alleles, and Fu and Li's F* statistic is significantly negative for the West Coast A-type alleles. These results are likely due to selection rather than demography, given that 10 of the housekeeping loci have no populations with significant values for any of the polymorphism statistics. The majority of codons in the fester proteins have ω values 95% posterior probability of ω values > 1. Conclusion Fester proteins are evolving non-neutrally. The polymorphism statistics are consistent with either

  3. Functional Analysis of the Coronary Heart Disease Risk Locus on Chromosome 21q22

    DEFF Research Database (Denmark)

    Beaney, Katherine E.; Smith, Andrew J. P.; Folkersen, Lasse Westergaard

    2017-01-01

    Background. The coronary heart disease (CHD) risk locus on 21q22 (lead SNP rs9982601) lies within a "gene desert." The aim of this study was to assess if this locus is associated with CHD risk factors and to identify the functional variant(s) and gene(s) involved. Methods. A phenome scan...

  4. PHIP - a novel candidate breast cancer susceptibility locus on 6q14.1

    NARCIS (Netherlands)

    Jiao, X. (Xiang); Aravidis, C. (Christos); Marikkannu, R. (Rajeshwari); Rantala, J. (Johanna); Picelli, S. (Simone); Adamovic, T. (Tatjana); Liu, T. (Tao); Maguire, P. (Paula); B. Kremeyer (Barbara); Luo, L. (Liping); von Holst, S. (Susanna); Kontham, V. (Vinaykumar); Thutkawkorapin, J. (Jessada); Margolin, S. (Sara); Du, Q. (Quan); Lundin, J. (Johanna); Michailidou, K. (Kyriaki); Bolla, M.K. (Manjeet K.); Wang, Q. (Qin); Dennis, J. (Joe); Lush, M. (Michael); C.B. Ambrosone (Christine); I.L. Andrulis (Irene); H. Anton-Culver (Hoda); Antonenkova, N.N. (Natalia N.); Arndt, V. (Volker); M.W. Beckmann (Matthias); C. Blomqvist (Carl); W.J. Blot (William); Boeckx, B. (Bram); S.E. Bojesen (Stig); B. Bonnani (Bernardo); J.S. Brand (Judith S.); H. Brauch (Hiltrud); H. Brenner (Hermann); A. Broeks (Annegien); T. Brüning (Thomas); B. Burwinkel (Barbara); Cai, Q. (Qiuyin); J. Chang-Claude (Jenny); NBCS Collaborators, (); Couch, F.J. (Fergus J.); A. Cox (Angela); S.S. Cross (Simon); S.L. Deming-Halverson (Sandra); P. Devilee (Peter); I. dos Santos Silva (Isabel); Dörk, T. (Thilo); M. Eriksson (Mats); P.A. Fasching (Peter); J.D. Figueroa (Jonine); D. Flesch-Janys (Dieter); H. Flyger (Henrik); M. Gabrielson (Marike); M. García-Closas (Montserrat); Giles, G.G. (Graham G.); A. González-Neira (Anna); P. Guénel (Pascal); Q. Guo (Qi); Gündert, M. (Melanie); C.A. Haiman (Christopher); Hallberg, E. (Emily); U. Hamann (Ute); P. harrington (Patricia); M.J. Hooning (Maartje); J.L. Hopper (John); Huang, G. (Guanmengqian); A. Jakubowska (Anna); M. Jones (Michael); M. Kerin (Michael); V-M. Kosma (Veli-Matti); Kristensen, V.N. (Vessela N.); Lambrechts, D. (Diether); L. Le Marchand (Loic); J. Lubinski (Jan); A. Mannermaa (Arto); J.W.M. Martens (John); A. Meindl (Alfons); R.L. Milne (Roger); A.-M. Mulligan (Anna-Marie); S.L. Neuhausen (Susan); H. Nevanlinna (Heli); J. Peto (Julian); K. Pykäs (Katri); P. Radice (Paolo); V. Rhenius (Valerie); E.J. Sawyer (Elinor); M.K. Schmidt (Marjanka); R.K. Schmutzler (Rita); C.M. Seynaeve (Caroline); Shah, M. (Mitul); J. Simard (Jacques); Southey, M.C. (Melissa C.); A.J. Swerdlow (Anthony ); T. Truong (Thérèse); Wendt, C. (Camilla); R. Winqvist (Robert); W. Zheng (Wei); kConFab/AOCS Investigators, (); J. Benítez (Javier); A.M. Dunning (Alison); P.D.P. Pharoah (Paul); D.F. Easton (Douglas); K. Czene (Kamila); P. Hall (Per); A. Lindblom (Annika)

    2017-01-01

    textabstractMost non-BRCA1/2 breast cancer families have no identified genetic cause. We used linkage and haplotype analyses in familial and sporadic breast cancer cases to identify a susceptibility locus on chromosome 6q. Two independent genome-wide linkage analysis studies suggested a 3 Mb locus

  5. PHIP - a novel candidate breast cancer susceptibility locus on 6q14.1

    DEFF Research Database (Denmark)

    Jiao, Xiang; Aravidis, Christos; Marikkannu, Rajeshwari

    2017-01-01

    Most non-BRCA1/2 breast cancer families have no identified genetic cause. We used linkage and haplotype analyses in familial and sporadic breast cancer cases to identify a susceptibility locus on chromosome 6q. Two independent genome-wide linkage analysis studies suggested a 3 Mb locus on chromos...

  6. Relationship Between Coping Strategies and Locus of Control With the Anxiety of Death in Old People

    Directory of Open Access Journals (Sweden)

    Hadi Hashemi Razini

    2017-09-01

    Conclusion Death anxiety is one of the key factors in the mental health of older adults. With regards to our findings, coping strategies and locus of control have an important role in death anxiety in older adults. Therefore, by designing psychological interventions based on coping strategies and changing locus of control from external to internal, death anxiety among the older adults can be improved.

  7. Self-Efficacy And Locus Of Control As Predictors Of Academic ...

    African Journals Online (AJOL)

    The study investigated self-efficacy and locus of control as predictor of academic achievement among Junior Secondary school students in Osun state Unity schools, using Self-Efficacy Scale (SES) and Locus of Control Scale (LOC) as measuring instruments. The Cronbach alpha coefficient for validity of the two instruments ...

  8. Locus of Control as It Relates to the Teaching Style of Elementary Teachers

    Science.gov (United States)

    Ture, Abidemi

    2013-01-01

    This research explored the relationship between elementary teachers' locus of control and teaching style. This research observed elementary teachers in their classrooms coupled with data gathered from information sheets, surveys, and interviews to determine if a relationship exists between the locus of control of the elementary teachers and…

  9. An Examination of Locus of Control, Epistemological Beliefs and Metacognitive Awareness in Preservice Early Childhood Teachers

    Science.gov (United States)

    Bedel, Emine Ferda

    2012-01-01

    This study aims to explore the locus of control, epistemological beliefs and metacognitive awareness levels of preservice early childhood education teachers and to determine the interrelations among these variables. 206 teacher candidates have been asked to fill out Rotter's Internal-External Locus of Control Scale, Central Epistemological Beliefs…

  10. The Relationship between the Perception of Own Locus of Control and Aggression of Adolescent Boys

    Science.gov (United States)

    Breet, Lettie; Myburgh, Chris; Poggenpoel, Marie

    2010-01-01

    Aggression is increasingly seen in most parts of South African society. Aggressive behaviour of boys in secondary school often results from frustrations caused by perceived high expectations of others regarding the role, locus of control, and personality of boys. Locus of control plays an important role in a person's perception concerning a…

  11. Predictors of Parental Locus of Control in Mothers of Pre- and Early Adolescents

    Science.gov (United States)

    Freed, Rachel D.; Tompson, Martha C.

    2011-01-01

    Parental locus of control refers to parents' perceived power and efficacy in child-rearing situations. This study explored parental locus of control and its correlates in 160 mothers of children ages 8 to 14 cross-sectionally and 1 year later. Maternal depression, maternal expressed emotion, and child internalizing and externalizing behavior were…

  12. Goal Orientations, Locus of Control and Academic Achievement in Prospective Teachers: An Individual Differences Perspective

    Science.gov (United States)

    Bulus, Mustafa

    2011-01-01

    The aim of this study is to investigate the role of the prospective teachers' locus of control in goal orientations and of both orientations in academic achievement. The participants were 270 undergraduate students studying in different majors at the Faculty of Education in Pamukkale University. Goal Orientations and Locus of Control Scales were…

  13. Social Self-Efficacy, Academic Locus of Control, and Internet Addiction

    Science.gov (United States)

    Iskender, Murat; Akin, Ahmet

    2010-01-01

    The purpose of this research is to examine the relationship of internet addiction, social self-efficacy, and academic locus of control. Participants were 311 university students who completed a questionnaire package that included the Online Cognition Scale, the Academic Locus of Control Scale, and the Perceived Social Self-efficacy Scale. The…

  14. Relationship of Personality and Locus of Control With Employment Outcomes among Participants with Spinal Cord Injury

    Science.gov (United States)

    Krause, James S.; Broderick, Lynne

    2006-01-01

    We investigated relationships among personality, locus of control, and current post-injury employment status for 1,391 participants with spinal cord injury. Participants with higher internality locus-of-control scores and activity scores (personality) reported more favorable employment outcomes. Higher scores on chance and powerful others (locus…

  15. The genetic and regulatory architecture of ERBB3-type 1 diabetes susceptibility locus

    DEFF Research Database (Denmark)

    Kaur, Simranjeet; Mirza, Aashiq H.; Brorsson, Caroline Anna

    2016-01-01

    -producing INS-1E cells and the genetic and regulatory architecture of the ERBB3 locus to provide insights to how rs2292239 may confer disease susceptibility. rs2292239 strongly correlated with residual β-cell function and metabolic control in children with T1D. ERBB3 locus associated lncRNA (NONHSAG011351...

  16. The interaction between the locus coeruleus and dorsal raphe nucleus studied with dual-probe microdialysis

    NARCIS (Netherlands)

    Pudovkina, OL; Cremers, TIFH; Westerink, BHC

    2002-01-01

    The interaction between the locus coeruleus and dorsal raphe nucleus was investigated by means of dual-probe microdialysis in conscious rats. The release of noradrenaline and 5-hydroxytryptamine (5-HT) after inhibition or stimulation of locus cocruleus and dorsal raphe activity was sampled in both

  17. A Study to Investigate the Relationship between Locus of Control and Academic Achievement of Students

    Science.gov (United States)

    Gujjar, Aijaz Ahmed; Aijaz, Rukhma

    2014-01-01

    Motivation is regarded as the alpha and omega of learning. It is the heart of teaching learning process. Motivation is defined as an internal state that arouses, directs, and maintains the behavior over time. Thus motivation is the pivotal component of learning and locus of control which is one of the important factors it stems from. Locus of…

  18. Mapping of panda plumage color locus on the microsatellite linkage map of the Japanese quail

    Directory of Open Access Journals (Sweden)

    Mizutani Makoto

    2006-01-01

    Full Text Available Abstract Background Panda (s is an autosomal recessive mutation, which displays overall white plumage color with spots of wild-type plumage in the Japanese quail (Coturnix japonica. In a previous study, the s locus was included in the same linkage group as serum albumin (Alb and vitamin-D binding protein (GC which are mapped on chicken (Gallus gallus chromosome 4 (GGA4. In this study, we mapped the s locus on the microsatellite linkage map of the Japanese quail by linkage analysis. Results Segregation data on the s locus were obtained from three-generation families (n = 106. Two microsatellite markers derived from the Japanese quail chromosome 4 (CJA04 and three microsatellite markers derived from GGA4 were genotyped in the three-generation families. We mapped the s locus between GUJ0026 and ABR0544 on CJA04. By comparative mapping with chicken, this locus was mapped between 10.0 Mb and 14.5 Mb region on GGA4. In this region, the endothelin receptor B subtype 2 gene (EDNRB2, an avian-specific paralog of the mammalian endothelin receptor B gene (EDNRB, is located. Because EDNRB is responsible for aganglionic megacolon and spot coat color in mouse, rat and equine, EDNRB2 is suggested to be a candidate gene for the s locus. Conclusion The s locus and the five microsatellite markers were mapped on CJA04 of the Japanese quail. EDNRB2 was suggested to be a candidate gene for the s locus.

  19. Fine-Scale Mapping of the FGFR2 Breast Cancer Risk Locus

    DEFF Research Database (Denmark)

    Meyer, Kerstin B; O'Reilly, Martin; Michailidou, Kyriaki

    2013-01-01

    The 10q26 locus in the second intron of FGFR2 is the locus most strongly associated with estrogen-receptor-positive breast cancer in genome-wide association studies. We conducted fine-scale mapping in case-control studies genotyped with a custom chip (iCOGS), comprising 41 studies (n = 89,050) of...

  20. A Locus of Control-based HIV and AIDS Risk Reduction Training ...

    African Journals Online (AJOL)

    The aim of this study was to investigate the effi cacy of a locus of control-based training programme in reducing HIV and AIDS risk among university students. The locus of control-based variables that formed the training programme were social systems control, deferment of gratifi cation, personal values and expectancies, ...

  1. The relationship between the perception of own locus of control and ...

    African Journals Online (AJOL)

    Aggression is increasingly seen in most parts of South African society. Aggressive behaviour of boys in secondary school often results from frustrations caused by perceived high expectations of others regarding the role, locus of control, and personality of boys. Locus of control plays an important role in a person's ...

  2. Hubungan antara Locus Of Control dan Efektivitas Komunikasi antar Pribadi dengan Problem Focused Coping

    Directory of Open Access Journals (Sweden)

    Eko Sujadi

    2016-03-01

    Full Text Available Problem focused coping need to be possessed by every individual. The purposes of this research were to described locus of control, the effectiveness of interpersonal communication, problem focused coping,the correlation between locus of control with problem focused coping, andthe correlationbetween the effectiveness of interpersonal communication with problem focused coping.This research was descriptive & correlation research by using quantitative approach. Data were collected through a Likert scale questionaire and locus of controlby using inventory Rotters Internal-External Locus of Control (I-E Scale, which was the validity and reliability has been tested. The data were analyzed by percentage technique and product moment correlation. The finding of research are:  1locus of control were in the middle range between internal locus of control and external locus of control with an average as big as 11.46, 2 the general level of effectiveness of interpersonal communication is in high category, 3 the general level of problem focused coping is in high category, 4 there is correlation between locus of control withproblem focused coping, and 5 there is correlation betweeneffectiveness of interpersonal communicationwithproblem focused coping.

  3. The Role of Locus of Control and Feedback on Performance of ...

    African Journals Online (AJOL)

    This study examined Students' Locus of Control and Teacher Feedback using a 2x3 factorial to measure the performance of thirty-six (36) primary school students utilizing the two locus of control types and three levels of teacher feedback: no feedback, attributional feedback, and progressive feedback. No significant ...

  4. Self Esteem, Locus of Control and Multidimensional Perfectionism as the Predictors of Subjective Well Being

    Science.gov (United States)

    Karatas, Zeynep; Tagay, Ozlem

    2012-01-01

    The purpose of this study is to determine whether there is a relationship between self-esteem, locus of control and multidimensional perfectionism, and the extent to which the variables of self-esteem, locus of control and multidimensional perfectionism contribute to the prediction of subjective well-being. The study was carried out with 318 final…

  5. The Relationship of Locus of Control and Learned Helplessness in Special Education Students.

    Science.gov (United States)

    Williams, Mary V.; Barber, William H.

    1992-01-01

    The question of whether special education students exhibit more learned helpless behavior and a more external locus of control than regular students is examined. The effects of these psychological conditions on school success are considered, and programs for alleviating learned helplessness and establishing a more internal locus of control are…

  6. Diversity of a microsatellite locus in the CSN1S1 gene in goat ...

    African Journals Online (AJOL)

    The purpose of this study was to investigate the diversity of the microsatellite locus at the CSN1S1 gene in goats raised in southeastern Turkey. DNA was isolated from blood samples collected from goats raised in Kilis (n= 30), Sanliurfa (n= 30) and Siirt (n= 30) provinces of Turkey. The microsatellite locus was amplified ...

  7. computer-aided root aided root aided root aided root-locus ...

    African Journals Online (AJOL)

    User

    AIDED ROOT-LOCUS NUMERICAL TECHNIQUE. LOCUS NUMERICAL TECHNIQUE. A. R. Zubair1,* , A. ... -loci obtained with this technique are found to confor loci obtained with this technique are found to confor loci are .... approaches which use complex analytic or semi- analytic representation that involve the use of.

  8. Young adult women: lifestyle and health locus of control.

    Science.gov (United States)

    Schank, M J; Lawrence, D M

    1993-08-01

    A study of 76 young adult women, 38 nursing students and 38 non-nursing students, examined their lifestyle practices and health locus of control (HLOC). Findings revealed a significant difference between reported lifestyle practices and the career choice of these young adult women. The lifestyle practice areas in which the most notable differences occurred included: use of seat belts, frequency of alcohol use, frequency of junk food intake, use of illegal drugs and hours of sleep per night. While differences in HLOC were evident between nursing and non-nursing students, no relationship was found between a young woman's HLOC and her lifestyle practices. The differences in HLOC showed that nurses were more frequently pure internal whereas most non-nurses were found to be double externals. The pure chance category had the fewest number of respondents. The difference in lifestyle practices between these young adult women can be explained in part by curriculum variations, as can the difference in HLOC patterns.

  9. Search for a schizophrenia susceptibility locus of human chromosome 22

    Energy Technology Data Exchange (ETDEWEB)

    Coon, H.; Hoff, M.; Holik, J. [Univ. of Utah Medical Center, Salt Lake City, UT (United States)] [and others

    1994-06-15

    We used 10 highly informative DNA polymorphic markers and genetic linkage analysis to examine whether a gene locus predisposing to schizophrenia is located on chromosome 22, in 105 families with schizophrenia and schizoaffective disorder. The LOD score method, including analysis for heterogeneity, provided no conclusive evidence of linkage under a dominant, recessive, or penetrance free model of inheritance. Affected sib-pair analysis was inconclusive. Affected Pedigree Member (APM) analysis gave only suggestive evidence for linkage. Multipoint APM analysis, using 4 adjacent loci including D22S281 and IL2RB, a region of interest from the APM analysis, gave non-significant results for the three different weighting functions. 18 refs., 1 fig., 7 tabs.

  10. Dynamic Quantitative Trait Locus Analysis of Plant Phenomic Data.

    Science.gov (United States)

    Li, Zitong; Sillanpää, Mikko J

    2015-12-01

    Advanced platforms have recently become available for automatic and systematic quantification of plant growth and development. These new techniques can efficiently produce multiple measurements of phenotypes over time, and introduce time as an extra dimension to quantitative trait locus (QTL) studies. Functional mapping utilizes a class of statistical models for identifying QTLs associated with the growth characteristics of interest. A major benefit of functional mapping is that it integrates information over multiple timepoints, and therefore could increase the statistical power for QTL detection. We review the current development of computationally efficient functional mapping methods which provide invaluable tools for analyzing large-scale timecourse data that are readily available in our post-genome era. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Natural history of the ERVWE1 endogenous retroviral locus

    Directory of Open Access Journals (Sweden)

    Duret Laurent

    2005-09-01

    Full Text Available Abstract Background The human HERV-W multicopy family includes a unique proviral locus, termed ERVWE1, whose full-length envelope ORF was preserved through evolution by the action of a selective pressure. The encoded Env protein (Syncytin is involved in hominoid placental physiology. Results In order to infer the natural history of this domestication process, a comparative genomic analysis of the human 7q21.2 syntenic regions in eutherians was performed. In primates, this region was progressively colonized by LTR-elements, leading to two different evolutionary pathways in Cercopithecidae and Hominidae, a genetic drift versus a domestication, respectively. Conclusion The preservation in Hominoids of a genomic structure consisting in the juxtaposition of a retrotransposon-derived MaLR LTR and the ERVWE1 provirus suggests a functional link between both elements.

  12. Evolution of an Expanded Sex Determining Locus in Volvox

    Science.gov (United States)

    Ferris, Patrick; Olson, Bradley J.S.C.; De Hoff, Peter L.; Douglass, Stephen; Diaz-Cano, David Casero; Prochnik, Simon; Geng, Sa; Rai, Rhitu; Grimwood, Jane; Schmutz, Jeremy; Nishii, Ichiro; Hamaji, Takashi; Nozaki, Hisayoshi; Pellegrini, Matteo; Umen, James G.

    2010-01-01

    Although dimorphic sexes have evolved repeatedly in multicellular eukaryotes, their origins are unknown. The mating locus (MT) of the sexually dimorphic multicellular green alga, Volvox carteri, specifies the production of eggs and sperm and has undergone a remarkable expansion and divergence relative to MT from Chlamydomonas reinhardtii, a closely related unicellular species that has equal-sized gametes. Transcriptome analysis revealed a rewired gametic expression program for Volvox MT genes relative to Chlamydomonas, and identified multiple gender-specific and sex-regulated transcripts. The retinoblastoma tumor suppressor homolog MAT3 is a Volvox MT gene that displays sexually regulated alternative splicing and evidence of gender-specific selection, both indicative of cooption into the sexual cycle. Thus, sex-determining loci impact the evolution of both sex-related and non-sex-related genes. PMID:20395508

  13. Differential expression and co-expression gene networks reveal candidate biomarkers of boar taint in non-castrated pigs

    DEFF Research Database (Denmark)

    Drag, Markus; Skinkyté-Juskiené, Ruta; Do, Duy N.

    2017-01-01

    metabolism (GSTO1, GSR, FMO3) of skatole and androstenone in liver to steroidgenesis (HSD17B7, HSD17B8, CYP27A1), regulation of steroidgenesis (STARD10, CYB5R3) and GnRH signalling (MAPK3, MAP2K2, MAP3K2) in testis. Overrepresented pathways included "Ribosome", "Protein export" and "Oxidative phosphorylation...

  14. The locus of semantic interference in picture naming

    Directory of Open Access Journals (Sweden)

    Pedro Macizo

    2003-01-01

    Full Text Available El locus del efecto de interferencia semántica en la denominación de dibujos. En los experimentos que se presentan se utilizó el procedimiento de priming enmascarado para explorar el locus del efecto de interferencia semántica. Para ello se manipuló la naturaleza de la tarea (denominación y decisión de género, el tipo de relación entre el prime y el target (semántica y fonológica y el tiempo de presentación del prime. Los resultados indicaron que el efecto de interferencia semántica aparece en las tareas de denominación (Experimento 1 y de decisión de género (Experimento 2, con tiempos de presentación del prime de 100 ms. Este resultado replica el efecto encontrado por otros investigadores y lo extiende a la tarea de decisión de género. Por otro lado, el efecto de facilitación fonológica no apareció en la tarea de decisión de género (Experimento 3. Este patrón de resultados sugiere que el efecto de interferencia semántica es consecuencia de procesos que ocurren en el nivel de representación del lemma, y que la tarea de decisión de género no está influenciada por la activación fonológica.

  15. Identification of a siderophore utilization locus in nontypeable Haemophilus influenzae

    Directory of Open Access Journals (Sweden)

    Seale Thomas W

    2010-04-01

    Full Text Available Abstract Background Haemophilus influenzae has an absolute aerobic growth requirement for either heme, or iron in the presence of protoporphyrin IX. Both iron and heme in the mammalian host are strictly limited in their availability to invading microorganisms. Many bacterial species overcome iron limitation in their environment by the synthesis and secretion of small iron binding molecules termed siderophores, which bind iron and deliver it into the bacterial cell via specific siderophore receptor proteins on the bacterial cell surface. There are currently no reports of siderophore production or utilization by H. influenzae. Results Comparative genomics revealed a putative four gene operon in the recently sequenced nontypeable H. influenzae strain R2846 that encodes predicted proteins exhibiting significant identity at the amino acid level to proteins involved in the utilization of the siderophore ferrichrome in other bacterial species. No siderophore biosynthesis genes were identified in the R2846 genome. Both comparative genomics and a PCR based analysis identified several additional H. influenzae strains possessing this operon. In growth curve assays strains containing the genes were able to utilize ferrichrome as an iron source. H. influenzae strains lacking the operon were unable to obtain iron from ferrichrome. An insertional mutation in one gene of the operon abrogated the ability of strains to utilize ferrichrome. In addition transcription of genes in the identified operon were repressible by high iron/heme levels in the growth media. Conclusions We have identified an iron/heme-repressible siderophore utilization locus present in several nontypeable H. influenzae strains. The same strains do not possess genes encoding proteins associated with siderophore synthesis. The siderophore utilization locus may enable the utilization of siderophores produced by other microorganisms in the polymicrobial environmental niche of the human nasopharynx

  16. Response to Selection in Finite Locus Models with Nonadditive Effects.

    Science.gov (United States)

    Esfandyari, Hadi; Henryon, Mark; Berg, Peer; Thomasen, Jørn Rind; Bijma, Piter; Sørensen, Anders Christian

    2017-05-01

    Under the finite-locus model in the absence of mutation, the additive genetic variation is expected to decrease when directional selection is acting on a population, according to quantitative-genetic theory. However, some theoretical studies of selection suggest that the level of additive variance can be sustained or even increased when nonadditive genetic effects are present. We tested the hypothesis that finite-locus models with both additive and nonadditive genetic effects maintain more additive genetic variance (VA) and realize larger medium- to long-term genetic gains than models with only additive effects when the trait under selection is subject to truncation selection. Four genetic models that included additive, dominance, and additive-by-additive epistatic effects were simulated. The simulated genome for individuals consisted of 25 chromosomes, each with a length of 1 M. One hundred bi-allelic QTL, 4 on each chromosome, were considered. In each generation, 100 sires and 100 dams were mated, producing 5 progeny per mating. The population was selected for a single trait (h2 = 0.1) for 100 discrete generations with selection on phenotype or BLUP-EBV. VA decreased with directional truncation selection even in presence of nonadditive genetic effects. Nonadditive effects influenced long-term response to selection and among genetic models additive gene action had highest response to selection. In addition, in all genetic models, BLUP-EBV resulted in a greater fixation of favorable and unfavorable alleles and higher response than phenotypic selection. In conclusion, for the schemes we simulated, the presence of nonadditive genetic effects had little effect in changes of additive variance and VA decreased by directional selection. © The American Genetic Association 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Association between the ABO locus and hematological traits in Korean

    Directory of Open Access Journals (Sweden)

    Hong Kyung-Won

    2012-09-01

    Full Text Available Abstract Background Recently, genome-wide association studies identified a pleiotropic gene locus, ABO, as being significantly associated with hematological traits. To confirm the effects of ABO on hematological traits, we examined the link between the ABO locus and hematological traits in Korean population-based cohorts. Results Six tagging SNPs for ABO were analyzed with regard to their effects on hematological traits [white blood cell count (WBC, red blood cell count (RBC, platelet (Plat, mean corpuscular volume (MCV, and mean corpuscular haemoglobin concentration (MCHC]. Linear regression analyses were performed, controlling for recruitment center, sex, and age as covariates. Of the 6 tagging SNPs, 3 (rs2073823, rs8176720, and rs495828 and 3 (rs2073823, rs8176717, and rs687289 were significantly associated with RBC and MCV, respectively (Bonferroni correction p-value criteria r2s = 0.99. Of the remaining 3 SNPs (rs8176720, rs8176717 and rs687289, rs8176717 generated an independent signal with moderate p-value (= 0.045 when it was adjusted for by rs2073823 (the most significant SNP. We also identified a copy number variation (CNV that was tagged by the SNP rs8176717, the minor allele of which correlated with the deletion allele of CNV. Our haplotype analysis indicated that the haplotype that contained the CNV deletion was significantly associated with MCV (β ± se = 0.363 ± 0.118, p =2.09 × 10-3. Conclusions Our findings confirm that ABO is one of the genetic factors that are associated with hematological traits in the Korean population. This result is notable, because GWASs fail to evaluate the link between a CNV and phenotype traits.

  18. USING INQUIRY-BASED TEACHING (5E IN TEACHING VOCABULARY VIEWED FROM STUDENTS’ LOCUS OF CONTROL

    Directory of Open Access Journals (Sweden)

    Rahmatika Kayyis

    2015-10-01

    Full Text Available Abstract The objectives of the research are to find out: (1 whether inquiry-based teaching is more effective than grammar-translation method to teach vocabulary; (2 whether the students who have high locus of control have better vocabulary than those who have low locus of control; and (3 whether there is an interaction between teaching methods and locus of control in teaching vocabulary.The factorial design method 2x2 was employed in this research. The population of the research was the students of fourth semester of STKIP Muhammadiyah Pringsewu Lampung in the academic year of 2014/2015. Based on the test of the hypotheses, it can be concluded that inquiry-based teaching is not significant effective method to teach vocabulary. The conclusion is the measurement effectiveness of the method is not determined by the levels of the students’ locus of control Keywords: Vocabulary, Inquiry Based Teaching, Locus of Control

  19. The Contribution of Locus of Control to Academic Procrastination in Islamic Education Management Students in Indonesia

    Directory of Open Access Journals (Sweden)

    Juliana Batubara

    2017-02-01

    Full Text Available This study aimed to describe the locus of control and academic procrastination, and investigate whether there is significance contributions of locus of control on student academic procrastination. This research was conducted by the Ex post-facto method was used in this study, where the data taken from two set of questionnaires. Proportional Stratified Random Sampling was used. There were 107 students involved this study. The results showed that the locus of control is in average level, meanwhile, and the students’ academic achievement was high. The study also showed that there is a significant contribution between the locus of control on students' academic procrastination. The article concludes that the importance that locus control for procrastination research, and with suggestions for educators who work with students who are adversely affected by procrastination.

  20. Detection and mapping of a lethal locus in a eucalyptus hybrid population

    Directory of Open Access Journals (Sweden)

    Tatiana Barbosa Rosado

    2011-09-01

    Full Text Available The objective of this work was to verify the existence of a lethal locus in a eucalyptus hybrid population, and to quantify the segregation distortion in the linkage group 3 of the Eucalyptus genome. A E. grandis x E. urophylla hybrid population, which segregates for rust resistance, was genotyped with 19 microsatellite markers belonging to linkage group 3 of the Eucalyptus genome. To quantify the segregation distortion, maximum likelihood (ML models, specific to outbreeding populations, were used. These models consider the observed marker genotypes and the lethal locus viability as parameters. The ML solutions were obtained using the expectation‑maximization algorithm. A lethal locus in the linkage group 3 was verified and mapped, with high confidence, between the microssatellites EMBRA 189 e EMBRA 122. This lethal locus causes an intense gametic selection from the male side. Its map position is 25 cM from the locus which controls the rust resistance in this population.

  1. Mesomelic dysplasia Kantaputra type is associated with duplications of the HOXD locus on chromosome 2q

    OpenAIRE

    Kantaputra, Piranit N; Klopocki, Eva; Hennig, Bianca P; Praphanphoj, Verayuth; Le Caignec, Cédric; Isidor, Bertrand; Kwee, Mei L; Shears, Deborah J; Mundlos, Stefan

    2010-01-01

    Mesomelic dysplasia Kantaputra type (MDK) is characterized by marked mesomelic shortening of the upper and lower limbs originally described in a Thai family. To identify the cause of MDK, we performed array CGH and identified two microduplications on chromosome 2 (2q31.1-q31.2) encompassing ∼481 and 507 kb, separated by a segment of normal copy number. The more centromeric duplication encompasses the entire HOXD cluster, as well as the neighboring genes EVX2 and MTX2. The breakpoints of the d...

  2. Organization of the cpe locus in CPE-positive clostridium perfringens type C and D isolates.

    Directory of Open Access Journals (Sweden)

    Jihong Li

    2010-06-01

    Full Text Available Clostridium perfringens enterotoxin (encoded by the cpe gene contributes to several important human, and possibly veterinary, enteric diseases. The current study investigated whether cpe locus organization in type C or D isolates resembles one of the three (one chromosomal and two plasmid-borne cpe loci commonly found amongst type A isolates. Multiplex PCR assays capable of detecting sequences in those type A cpe loci failed to amplify products from cpe-positive type C and D isolates, indicating these isolates possess different cpe locus arrangements. Therefore, restriction fragments containing the cpe gene were cloned and sequenced from two type C isolates and one type D isolate. The obtained cpe locus sequences were then used to construct an overlapping PCR assay to assess cpe locus diversity amongst other cpe-positive type C and D isolates. All seven surveyed cpe-positive type C isolates had a plasmid-borne cpe locus partially resembling the cpe locus of type A isolates carrying a chromosomal cpe gene. In contrast, all eight type D isolates shared the same plasmid-borne cpe locus, which differed substantially from the cpe locus present in other C. perfringens by containing two copies of an ORF with 67% identity to a transposase gene (COG4644 found in Tn1546, but not previously associated with the cpe gene. These results identify greater diversity amongst cpe locus organization than previously appreciated, providing new insights into cpe locus evolution. Finally, evidence for cpe gene mobilization was found for both type C and D isolates, which could explain their cpe plasmid diversity.

  3. Transcription and chromatin organization of a housekeeping gene cluster containing an integrated β-globin locus control region

    NARCIS (Netherlands)

    D. Noordermeer (Daan); M.R. Branco (Miguel); E. Splinter (Erik); P. Klous (Petra); W.F.J. van IJcken (Wilfred); S.M.A. Swagemakers (Sigrid); M. Koutsourakis (Manousos); P.J. van der Spek (Peter); A. Pombo (Ana); W.L. de Laat (Wouter)

    2008-01-01

    textabstractThe activity of locus control regions (LCR) has been correlated with chromatin decondensation, spreading of active chromatin marks, locus repositioning away from its chromosome territory (CT), increased association with transcription factories, and long-range interactions via chromatin

  4. Incomplete concerted evolution and reproductive isolation at the rDNA locus uncovers nine cryptic species within Anopheles longirostris from Papua New Guinea

    Directory of Open Access Journals (Sweden)

    Cooper Robert D

    2010-12-01

    Full Text Available Abstract Background Nuclear ribosomal DNA (rDNA genes and transcribed spacers are highly utilized as taxonomic markers in metazoans despite the lack of a cohesive understanding of their evolution. Here we follow the evolution of the rDNA second internal transcribed spacer (ITS2 and the mitochondrial DNA cytochrome oxidase I subunit in the malaria mosquito Anopheles longirostris from Papua New Guinea (PNG. This morphospecies inhabits a variety of ecological environments indicating that it may comprise a complex of morphologically indistinguishable species. Using collections from over 70 sites in PNG, the mtDNA was assessed via direct DNA sequencing while the ITS2 was assessed at three levels - crude sequence variation through restriction digest, intragenomic copy variant organisation (homogenisation through heteroduplex analysis and DNA sequencing via cloning. Results Genetic evaluation of over 300 individuals revealed that A. longirostris comprises eight ITS2 PCR-RFLP genotypes and nine ITS2 heteroduplex genotypes showing distinct copy variant organization profiles after PCR amplification. Seven of these nine genotypes were found to be sympatric with other genotypes. Phylogenetic analysis of cloned ITS2 PCR products and mtDNA COI confirmed all nine clades with evidence of reproductive isolation at the rDNA locus. Compensatory base changes in the ITS2 secondary structure or in pseudoknots were absent when closely related species were assessed. Individuals from each ITS2 genotype showed the same copy variant heteroduplex profile suggesting that the rDNA array is fixed within each genotype. Conclusion The centromere-proximal position of the rDNA array in Anopheles mosquitoes has probably reduced interchromosomal recombination leaving intrachromosomal events responsible for the observed pattern of concerted evolution we see in these mosquitoes. The stability of these intragenomic ITS2 copy variants within individuals and interbreeding populations

  5. Relationships of Locus of Control to Self Esteem, Academic Achievement, and Prediction of Performance among Nigerian Secondary School Pupils.

    Science.gov (United States)

    Maqsud, M.

    1983-01-01

    Among Nigerian secondary school boys, (1) socioeconomic background, locus of control, intelligence, and self-esteem positively affected academic achievement; (2) internal locus of control was positively correlated with intelligence, self-esteem, and academic achievement; and (3) internals (on locus of control) predicted their own academic…

  6. The 3D-structure of the Immunoglobulin Heavy Chain Locus: implications for long-range genomic interactions [supplemental data

    NARCIS (Netherlands)

    S. Jhunjhunwala (Suchit); M.C. van Zelm (Menno); M.M. Peak (Mandy); S. Cutchin (Steve); R. Riblet (Roy); J.J.M. van Dongen (Jacques); F.G. Grosveld (Frank); T.A. Knoch (Tobias); C. Murre (Cornelis)

    2008-01-01

    textabstractThe immunoglobulin heavy-chain (Igh) locus is organized into distinct regions that contain multiple variable (VH), diversity (DH), joining (JH) and constant (CH) coding elements. How the Igh locus is structured in 3D space is unknown. To probe the topography of the Igh locus,

  7. Weight loss maintenance in relation to locus of control: The MedWeight study.

    Science.gov (United States)

    Anastasiou, Costas A; Fappa, Evaggelia; Karfopoulou, Eleni; Gkza, Anastasia; Yannakoulia, Mary

    2015-08-01

    Locus of control, i.e. the degree of an individual's belief on the control of his/her life, has been related to many health outcomes, including weight loss in overweight/obese individuals. No information is available on the impact of locus of control in maintaining weight loss. We aimed to investigate the effect of locus of control in weight loss maintenance and explore potential associations with lifestyle factors. Study participants included 239 individuals (41% males) who had lost at least 10% of body weight in the past and either maintained the loss (maintainers: weight maintenance of at least 10% of initial weight) or regained it (regainers). Locus of control was defined by a relevant multi-dimensional scale; participants were categorised to internals and externals, based on "internal" and "others" sub-scales. A significant interaction was found between locus of control and weight loss maintenance status (p locus of control. Individualised treatment, according to locus of control, may increase weight loss maintenance rates in former overweight/obese individuals. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Impact of divorce on locus of control orientation in adult women: a longitudinal study.

    Science.gov (United States)

    Doherty, W J

    1983-04-01

    Using longitudinal data for adult women from the National Longitudinal Surveys of Labor Market Experience, this study examined the relation between getting divorced and changes in the individual's locus of control orientation. The sample contained 1,814 white women ages 32-46 years who were in their first marriage in 1969. Marital status and locus of control (an 11-item abbreviated version of Rotter's Internal-External Locus of Control Scale) were measured in 1969, 1972, and 1977. Based on previous literature on locus of control and life events and on divorce, stress, and mental health, the author hypothesized that divorced people, in comparison with those who remained married, would show a short-term increase in externality from 1969-1972, followed by a return over the next 5 years to levels of locus of control comparable to that of the group who remained married. It was also hypothesized that locus of control scores would not predict the likelihood of becoming divorced over the 8-year period. All three hypotheses were confirmed. The findings were discussed in the context of two larger theoretical issues: the influence of important life events on locus of control and the causal direction in the well-documented association between divorce and mental health.

  9. Buffering Role of Locus of Control on Stress among the College/University Teachers of Bahawalpur

    Directory of Open Access Journals (Sweden)

    Aqeel Ahmad Khan (Corresponding author

    2012-06-01

    Full Text Available The present research is aimed to ascertain the role of locus of control in mediating or coping on various degree/levels of stress among the college/university teachers of Bahawalpur. For that purpose a sample of N=200 male/female college/university teacherswas selected by convenient sampling. Research tools, Locus of control by Julian Rotter (1966 and Stress questionnaire by International Stress Management Association UK, (2009 were administered for data collection. After the collection of data it was analyzedby SPSS. The results shows that the teachers identified with internal locus of control reveal low level of stress as contrast to the teachers with external locus of control. The study also confirms that high internal locus of control determines high coping andmediating ability of stress among the teachers. The study also pointed out that the teachers with external locus of control were more incline or prone to stress. Furthermore, Pearson and Spearman’s Correlation results at significant level of .000 show that bothvariables are highly correlated. Similarly, overall Mean of locus of control and Coefficient of variation reveals the high consistency role in relation with stress.

  10. Contribution of glutamatergic systems in locus coeruleus to nucleus paragigantocellularis stimulation-evoked behavior.

    Science.gov (United States)

    Liu, N; Ho, I K; Rockhold, R W

    1999-08-01

    The role of extracellular glutamate, within the locus coeruleus, in mediation of the behavioral signs elicited by electrical stimulation of the nucleus paragigantocellularis (PGi) was investigated in conscious, opioid-naive rats. Each rat was prepared with a chronically implanted unilateral electrode within the PGi and a microdialysis guide cannula directed at the ipsilateral locus coeruleus. Opioid withdrawal-like behaviors (rearing, teeth-chattering, wet-dog shakes, etc.) and increases in extracellular glutamate concentrations within the locus coeruleus were evoked, in a frequency-dependent (0.5-50 Hz) manner, during PGi stimulation. Reverse dialysis perfusion of the locus coeruleus with the nonspecific glutamate receptor antagonist, kynurenic acid (0.1, 1 mM), reduced the intensity of stimulation-induced behaviors by roughly 50%, but had no effect on the corresponding increases in glutamate concentrations. Perfusion of the locus coeruleus with the glutamate transporter inhibitor, L-trans-pyrrolidine dicarboxylic acid, at 1, but not at 0.1, mM significantly increased glutamate levels in dialysates. Neither concentration of the transporter inhibitor altered the behavioral score. The results indicate that the opioid withdrawal-like behaviors elicited by electrical stimulation of the brainstem at the site of the PGi are positively correlated with locus coeruleus levels of glutamate, and suggest further that the behaviors are partially mediated by release of glutamate within the locus coeruleus or its immediate vicinity.

  11. Internal health locus of control predicts willingness to track health behaviors online and with smartphone applications.

    Science.gov (United States)

    Bennett, Brooke L; Goldstein, Carly M; Gathright, Emily C; Hughes, Joel W; Latner, Janet D

    2017-12-01

    Given rising technology use across all demographic groups, digital interventions offer a potential strategy for increasing access to health information and care. Research is lacking on identifying individual differences that impact willingness to use digital interventions, which may affect patient engagement. Health locus of control, the amount of control an individual believes they have over their own health, may predict willingness to use mobile health (mHealth) applications ('apps') and online trackers. A cross-sectional study (n = 276) was conducted to assess college students' health locus of control beliefs and willingness to use health apps and online trackers. Internal and powerful other health locus of control beliefs predicted willingness to use health apps and online trackers while chance health locus of control beliefs did not. Individuals with internal and powerful other health locus of control beliefs are more willing than those with chance health locus of control beliefs to utilize a form of technology to monitor or change health behaviors. Health locus of control is an easy-to-assess patient characteristic providers can measure to identify which patients are more likely to utilize mHealth apps and online trackers.

  12. Prevalence of Porphyromonas gingivalis four rag locus genotypes in patients of orthodontic gingivitis and periodontitis.

    Science.gov (United States)

    Liu, Yi; Zhang, Yujie; Wang, Lili; Guo, Yang; Xiao, Shuiqing

    2013-01-01

    Porphyromonas gingivalis is considered as a major etiological agent in periodontal diseases and implied to result in gingival inflammation under orthodontic appliance. rag locus is a pathogenicity island found in Porphyromonas gingivalis. Four rag locus variants are different in pathogenicity of Porphyromonas gingivalis. Moreover, there are different racial and geographic differences in distribution of rag locus genotypes. In this study, we assessed the prevalence of Porphyromonas gingivalis and rag locus genotypes in 102 gingival crevicular fluid samples from 57 cases of gingivitis patients with orthodontic appliances, 25 cases of periodontitis patients and 20 cases of periodontally healthy people through a 16S rRNA-based PCR and a multiplex PCR. The correlations between Porphyromona.gingivalis/rag locus and clinical indices were analyzed. The prevalence of Porphyromonas gingivalis and rag locus genes in periodontitis group was the highest among three groups and higher in orthodontic gingivitis than healthy people (pPorphyromonas gingivalis/rag locus and gingival index. rag-3 and rag-4 were the predominant genotypes in the patients of orthodontic gingivitis and mild-to-moderate periodontitis in Shandong. Porphyromonas.gingivalis carrying rag-1 has the strong virulence and could be associated with severe periodontitis.

  13. Organization and evolutionary trajectory of the mating type (MAT) locus in dermatophyte and dimorphic fungal pathogens.

    Science.gov (United States)

    Li, Wenjun; Metin, Banu; White, Theodore C; Heitman, Joseph

    2010-01-01

    Sexual reproduction in fungi is governed by a specialized genomic region, the mating type (MAT) locus, whose gene identity, organization, and complexity are diverse. We identified the MAT locus of five dermatophyte fungal pathogens (Microsporum gypseum, Microsporum canis, Trichophyton equinum, Trichophyton rubrum, and Trichophyton tonsurans) and a dimorphic fungus, Paracoccidioides brasiliensis, and performed phylogenetic analyses. The identified MAT locus idiomorphs of M. gypseum control cell type identity in mating assays, and recombinant progeny were produced. Virulence tests in Galleria mellonella larvae suggest the two mating types of M. gypseum may have equivalent virulence. Synteny analysis revealed common features of the MAT locus shared among these five dermatophytes: namely, a small size ( approximately 3 kb) and a novel gene arrangement. The SLA2, COX13, and APN2 genes, which flank the MAT locus in other Ascomycota are instead linked on one side of the dermatophyte MAT locus. In addition, the transcriptional orientations of the APN2 and COX13 genes are reversed compared to the dimorphic fungi Histoplasma capsulatum, Coccidioides immitis, and Coccidioides posadasii. A putative transposable element, pogo, was found to have inserted in the MAT1-2 idiomorph of one P. brasiliensis strain but not others. In conclusion, the evolution of the MAT locus of the dermatophytes and dimorphic fungi from the last common ancestor has been punctuated by both gene acquisition and expansion, and asymmetric gene loss. These studies further support a foundation to develop molecular and genetic tools for dermatophyte and dimorphic human fungal pathogens.

  14. Work stress and emotional exhaustion in nurses: the mediating role of internal locus of control.

    Science.gov (United States)

    Partlak Günüşen, Neslihan; Ustün, Besti; Erdem, Sabri

    2014-01-01

    Burnout is a major problem for nursing. There is a strong relationship between work stress and emotional exhaustion. Although studies report a negative correlation between the internal locus of control and emotional exhaustion and work stress, the number of studies available on the subject is limited. This study intends to examine the extent to which the relationship between work stress and emotional exhaustion is mediated by nurses' internal locus of control. The study adopted a cross-sectional survey design. The data were analyzed using structural equation modeling techniques. The study sample consisted of 347 nurses who worked in a university hospital in Izmir, Turkey and who agreed to participate in the study. The Work-Related Strain Inventory was used to evaluate the nurses' work stress level, Maslach Burnout Inventory was used to evaluate their emotional exhaustion levels, and the Locus of Control Scale was used to evaluate the internal locus of control. The variables of the study were based on the Neuman Systems Model. Work stress was positively related to internal locus of control (β3 = .21, p exhaustion (β = -.03, p > 0.1). Internal locus of control was negatively related to emotional exhaustion (β = -.14, p exhaustion (mediated by internal locus of control β = .84, p exhaustion (mediated by internal locus of control, β = .84, p exhaustion and work stress was mediated, the impact of internal locus of control was limited. It is recommended that different variables be included in future studies so that they can mediate the relationship between work stress and emotional exhaustion.

  15. A third locus for autosomal dominant cerebellar ataxia Type I maps to chromosome 14q24. 3-qter: Evidence for the existence of a fourth locus

    Energy Technology Data Exchange (ETDEWEB)

    Stevanin, G.; Guern, E.L.; Ravise, N.; Chneiweiss, H.; Duerr, A.; Cancel, G.; Vignal, A.; Boch, A.L.; Ruberg, M.; Penet, C.; Pothin, Y.; Lagroua, I.; Haguenau, M.; Rancurel, G.; Weissenbach, J.; Agid, Y.; Brice, A.

    1994-01-01

    The autosomal dominant cerebellar ataxias (ADCA) type I are a group of neurological disorders that are clinically and genetically heterogeneous. Two genes implicated in the disease, SCA1 (spinal cerebellar ataxia 1) and SCA2, are already localized. The authors have mapped a third locus to chromosome 14q24.3-qter, by linkage analysis in a non-SCA1/non-SCA2 family and have confirmed its existence in a second such family. The authors suggest designating this new locus [open quotes]SCA3.[close quotes] Combined analysis of the two families restricted the SCA3 locus to a 15-cM interval between markers D14S67 and D14S81. The gene for Machado-Joseph disease (MJD), a clinically different form of ADCA type I, has been recently assigned to chromosome 14q24.3-q32. Although the SCA3 locus is within the MJD region, linkage analyses cannot yet demonstrate whether they result from mutations of the same gene. Linkage to all three loci (SCA1, SCA2, and SCA3) was excluded in another family, which indicates the existence of a fourth ADCA type I locus. 36 refs., 4 figs., 3 tabs.

  16. Evidence for a third genetic locus for autosomal dominant polycystic kidney disease

    Energy Technology Data Exchange (ETDEWEB)

    Daoust, M.C.; Bichet, D.G. [Universite de Montreal, Quebec (Canada); Reynolds, D.M. [Albert Einstein College of Medicine, Bronx, NY (United States)] [and others

    1995-02-10

    Autosomal dominant polycystic kidney disease (ADPKD) is a genetically heterogeneous disease with loci on chromosomes 16p and 4q. It has a moderately high spontaneous mutation rate, although the relative frequency of such mutations at each gene locus is unknown. In studying genetic heterogeneity in the French-Canadian population, we identified a family in which a classical clinical presentation of ADPKD resulted from a mutation at a locus genetically distinct from either of the previously described loci for this disease. This suggests the existence of a third genetic locus for ADPKD. 21 refs., 1 fig., 1 tab.

  17. Unequal segregation of SRK alleles at the S locus in Brassica cretica.

    Science.gov (United States)

    Edh, Kristina; Widén, Björn; Ceplitis, Alf

    2008-06-01

    In the Brassicaceae plant family, which includes the Arabidopsis and Brassica genera, self-incompatibility (SI) is controlled by genes at the S locus. Using experimental crosses, we studied the pattern of inheritance of S-locus alleles in the wild species Brassica cretica. Four full-sib families were established and unequal segregation of alleles at the SRK SI gene was found in one family. The segregation distortion acted in favour of a recessive (class II) allele and was best explained by some form of gametic-level selection. Our findings are discussed in the light of theoretical predictions of differential accumulation of deleterious mutations among S-locus alleles.

  18. Personal networks and locus of control in large urban centers of Argentina

    Directory of Open Access Journals (Sweden)

    Pablo De Grande

    2013-12-01

    Full Text Available This study analyzes the relationship between locus of control and interpersonal relations structures in Argentina. After a representative sample (n = 1500 of households in seven major urban centers (>200,000 inhabitants, it examines the relationship between the externality of locus of control and different aspects of personal networks of each respondent. The results show that people having more relations experiment lower levels of externality of locus of control. Likewise, lower levels of externality are informed when personal ties outside the neighborhood are available, as well as ties high educational level. In this regard, significant associations are verified between control and personal relations structures.

  19. Fine Structure and Instability of the Ml-a Locus in Barley

    OpenAIRE

    Wise, Roger P.; Ellingboe, Albert H.

    1985-01-01

    There are many naturally occurring variants at the Ml-a locus in barley that confer resistance to the powdery mildew fungus Erysiphe graminis f. sp. hordei. Since the Ml-a locus is bracketed by Hor-1 and Hor-2, genes that encode storage proteins in the endosperm, the Ml-a locus is amenable to fine structure analysis. Rare susceptible recombinants, as judged by exchange of flanking markers, were recovered in F3 families from the Ml-a10 x Ml-a1, Ml-a1 x Ml-a15 and Ml-a6 x Ml-a13 crosses. Some...

  20. A comparative study of entrepreneurs and managers: stress, burnout, locus of control, and social support.

    Science.gov (United States)

    Rahim, M A

    1995-01-01

    This study investigated the relationships of job stress to job burnout, of locus of control and social support to stress and burnout, and the moderating effects of locus of control and social support on the stress-burnout relationship. These relationships were tested with questionnaire data collected from a random sample of entrepreneurs (N = 238) and managers (N = 288). Results showed that entrepreneurs reported that they had higher internal locus of control, received less social support, and had less job burnout than managers. Hierarchical regression analyses found support for eight of the ten main effects and one of the four moderating effects.

  1. The Examination of Pre-school Teacher Candidates’ Academic Locus of Control Levels According to Gender and Grade

    OpenAIRE

    Hakan Sarıçam; Ayşe Duran; Mehmet Çardak; Medera HALMATOV

    2012-01-01

    The aim of this study is to examine the level of academic locus of control of the students who study pre-school education program. The sample of study is 329 students selected randomly in Faculty of Education from a mid-sized state University. In the study, Personal Information Form and Academic Locus of Control Scale prepared by researchers were used. Academic Locus of Control Scale includes two sub-dimensions; internal locus of control and external locus of control. Independent samples t t...

  2. Locus coeruleus, norepinephrine and Aβ peptides in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Jennifer A. Ross

    2015-01-01

    Full Text Available Monoaminergic brainstem systems have widespread projections that participate in many central processes and, when dysregulated, contribute to a plethora of neuropsychiatric and neurodegenerative disorders. Synapses are the foundation of these neuronal circuits, and their local dysfunction results in global aberrations leading to pathophysiological disease states. This review focuses on the locus coeruleus (LC norepinephrine (NE brainstem system and its underappreciated role in Alzheimer's disease (AD. Amyloid beta (Aβ, a peptide that accumulates aberrantly in AD has recently been implicated as a modulator of neuronal excitability at the synapse. Evidence is presented showing that disruption of the LC-NE system at a synaptic and circuit level during early stages of AD, due to conditions such as chronic stress, can potentially lead to amyloid accumulation and contribute to the progression of this neurodegenerative disorder. Additional factors that impact neurodegeneration include neuroinflammation, and network de-synchronization. Consequently, targeting the LC-NE system may have significant therapeutic potential for AD, as it may facilitate modulation of Aβ production, curtail neuroinflammation, and prevent sleep and behavioral disturbances that often lead to negative patient outcomes.

  3. An Extracellular Polysaccharide Locus Required for Transmission of Bordetella bronchiseptica.

    Science.gov (United States)

    Dewan, Kalyan K; Taylor-Mulneix, Dawn L; Hilburger, Lindsay J; Rivera, Israel; Preston, Andrew; Harvill, Eric T

    2017-10-17

    The lack of animal models to experimentally study how infectious agents transmit between hosts limits our understanding of what makes some pathogens so contagious. We recently developed a Bordetella bronchiseptica mouse model to study transmission and have used it to assess, for the first time, which of several well-studied "virulence factors" common to classical Bordetella species contribute to transmission. Among 13 mutants screened, a mutant lacking an extracellular polysaccharide (EPS) locus consistently failed to transmit. The loss of EPS had no obvious effect on in vitro characteristics of growth, adherence, cytotoxicity, or serum resistance, though it profoundly reduced the ability of the mutant to colonize the lower respiratory tract of mice. While wild-type B. bronchiseptica was shed from colonized mice and efficiently transmitted to cage-mates, the mutant colonized less efficiently, shed at lower numbers, and consequently did not transmit to naive animals. These results have important implications for potential roles of polysaccharides in the pathogenesis and transmission of Bordetella species as well as other respiratory pathogens. Cases of pertussis (whooping cough) caused by Bordetella pertussis are on the rise, and understanding factors that contribute to their spread is critical to its control.

  4. Locus Coeruleus and Dopamine-Dependent Memory Consolidation

    Directory of Open Access Journals (Sweden)

    Miwako Yamasaki

    2017-01-01

    Full Text Available Most everyday memories including many episodic-like memories that we may form automatically in the hippocampus (HPC are forgotten, while some of them are retained for a long time by a memory stabilization process, called initial memory consolidation. Specifically, the retention of everyday memory is enhanced, in humans and animals, when something novel happens shortly before or after the time of encoding. Converging evidence has indicated that dopamine (DA signaling via D1/D5 receptors in HPC is required for persistence of synaptic plasticity and memory, thereby playing an important role in the novelty-associated memory enhancement. In this review paper, we aim to provide an overview of the key findings related to D1/D5 receptor-dependent persistence of synaptic plasticity and memory in HPC, especially focusing on the emerging evidence for a role of the locus coeruleus (LC in DA-dependent memory consolidation. We then refer to candidate brain areas and circuits that might be responsible for detection and transmission of the environmental novelty signal and molecular and anatomical evidence for the LC-DA system. We also discuss molecular mechanisms that might mediate the environmental novelty-associated memory enhancement, including plasticity-related proteins that are involved in initial memory consolidation processes in HPC.

  5. The locus of taboo context effects in picture naming.

    Science.gov (United States)

    Hansen, Samuel J; McMahon, Katie L; Burt, Jennifer S; de Zubicaray, Greig I

    2016-07-20

    Speakers respond more slowly when naming pictures presented with taboo (i.e., offensive/embarrassing) than with neutral distractor words in the picture-word interference paradigm. Over four experiments, we attempted to localize the processing stage at which this effect occurs during word production and determine whether it reflects the socially offensive/embarrassing nature of the stimuli. Experiment 1 demonstrated taboo interference at early stimulus onset asynchronies of -150 ms and 0 ms although not at 150 ms. In Experiment 2, taboo distractors sharing initial phonemes with target picture names eliminated the interference effect. Using additive factors logic, Experiment 3 demonstrated that taboo interference and phonological facilitation effects do not interact, indicating that the two effects originate at different processing levels within the speech production system. In Experiment 4, interference was observed for masked taboo distractors, including those sharing initial phonemes with the target picture names, indicating that the effect cannot be attributed to a processing level involving responses in an output buffer. In two of the four experiments, the magnitude of the interference effect correlated significantly with arousal ratings of the taboo words. However, no significant correlations were found for either offensiveness or valence ratings. These findings are consistent with a locus for the taboo interference effect prior to the processing stage responsible for word form encoding. We propose a pre-lexical account in which taboo distractors capture attention at the expense of target picture processing due to their high arousal levels.

  6. Molecular studies of deletions at the human steroid sulfatase locus

    Energy Technology Data Exchange (ETDEWEB)

    Shapiro, L.J.; Yen, P.; Pomerantz, D.; Martin, E.; Rolewic, L.; Mohandas, T. (Univ. of California, Los Angeles (USA))

    1989-11-01

    The human steroid sulfatase gene (STS) is located on the distal X chromosome short arm close to the pseudoautosomal region but in a segment of DNA that is unique to the X chromosome. In contrast to most X chromosome-encoded genes, STS expression is not extinguished during the process of X chromosome inactivation. Deficiency of STS activity produced the syndrome of X chromosome-linked ichthyosis, which is one of the most common inborn errors of metabolism in man. Approximately 90% of STS{sup {minus}} individuals have large deletions at the STS locus. The authors and others have found that the end points of such deletions are heterogeneous in their location. One recently ascertained subject was observed to have a 40-kilobase deletion that is entirely intragenic, permitting the cloning and sequencing of the deletion junction. Studies of this patient and of other X chromosome sequences in other subjects permit some insight into the mechanism(s) responsible for generating frequent deletions on the short arm of the X chromosome.

  7. Polarized gene conversion at the bz locus of maize.

    Science.gov (United States)

    Dooner, Hugo K; He, Limei

    2014-09-23

    Nucleotide diversity is greater in maize than in most organisms studied to date, so allelic pairs in a hybrid tend to be highly polymorphic. Most recombination events between such pairs of maize polymorphic alleles are crossovers. However, intragenic recombination events not associated with flanking marker exchange, corresponding to noncrossover gene conversions, predominate between alleles derived from the same progenitor. In these dimorphic heterozygotes, the two alleles differ only at the two mutant sites between which recombination is being measured. To investigate whether gene conversion at the bz locus is polarized, two large diallel crossing matrices involving mutant sites spread across the bz gene were performed and more than 2,500 intragenic recombinants were scored. In both diallels, around 90% of recombinants could be accounted for by gene conversion. Furthermore, conversion exhibited a striking polarity, with sites located within 150 bp of the start and stop codons converting more frequently than sites located in the middle of the gene. The implications of these findings are discussed with reference to recent data from genome-wide studies in other plants.

  8. Targeted transposition at the vestigial locus of Drosophila melanogaster.

    Science.gov (United States)

    Heslip, T R; Hodgetts, R B

    1994-12-01

    Targeted transposition is the replacement of one P element with another. We are exploiting this unique property of P elements to study the complex regulatory domain of the Dopa decarboxylase (Ddc) gene in Drosophila melanogaster. P element constructs targeted to the same site in the genome will be subjected to the same position effect. This allows the subtle effects typical of most mutations in the Ddc regulatory region to be measured in the absence of the variable influences of position effects which are associated with the current method of germline transformation. We have investigated some of the parameters affecting targeted transposition of a Ddc transposon, P[Ddc], into a P element allele at the vestigial locus. These events were detected by an increased mutant vg phenotype. The location of the donor transposon in cis or in trans to the target had little effect on the frequency of targeting. Likewise, the mobility of different donor elements, as measured by their rate of transposition to a different chromosome, varied nearly 20-fold, while the rate of targeted transposition was very similar between them. All targeted alleles were precise replacements of the target P element by P[Ddc], but in several cases the donor was inserted in the opposite orientation. The targeted alleles could be described as the result of a replicative, conversion-like event.

  9. The functional organization of the vestigial locus in Drosophila melanogaster.

    Science.gov (United States)

    Williams, J A; Atkin, A L; Bell, J B

    1990-03-01

    Vestigial mutants are associated with imaginal disc cell death which results in the deletion of adult wing and haltere structures. The vestigial locus has previously been cloned, and mutational lesions associated with a number of vg alleles were mapped within a 19 kb DNA region defined as essential for vg function. Herein we report the identification and characterization of a developmentally regulated 3.8 kb vg transcript which is spliced from exons distributed throughout the essential interval defined above. All the characterized classical alleles have predictable effects on this transcription unit, and the severity of this effect is directly proportional to the severity of the wing phenotype. A repetitive domain within this transcription unit was identified and may serve as a tag to isolate other genes with functions related to vg. We also report an exceptional vg allele (vg83b27) that produces an extreme wing and haltere phenotype, but which defines a second vg complementation unit. This allele is associated with a 4 kb deletion entirely within a 4.5 kb vg intron as defined by the 3.8 kb transcription unit. Molecular and genetic evidence indicates that the vg83b27 mutation has a functional 3.8 kb transcription unit, thus accounting for its ability to complement classical alleles. The results indicate that sequences within a vg intron are essential for normal wing and haltere development.

  10. Locus coeruleus and dopaminergic consolidation of everyday memory

    Science.gov (United States)

    Takeuchi, Tomonori; Duszkiewicz, Adrian J.; Sonneborn, Alex; Spooner, Patrick A.; Yamasaki, Miwako; Watanabe, Masahiko; Smith, Caroline C.; Fernández, Guillén; Deisseroth, Karl; Greene, Robert W.; Morris, Richard G. M.

    2016-01-01

    Summary The retention of episodic-like memory is enhanced, in humans and animals, when something novel happens shortly before or after encoding. Using an everyday memory task in mice, we sought the neurons mediating this dopamine-dependent novelty effect, previously thought to originate exclusively from the tyrosine hydroxylase-expressing (TH+) neurons in the ventral tegmental area (VTA). We report that neuronal firing in the locus coeruleus (LC) is especially sensitive to environmental novelty, LC-TH+ neurons project more profusely than VTA-TH+ neurons to the hippocampus, optogenetic activation of LC-TH+ neurons mimics the novelty effect, and this novelty-associated memory enhancement is unaffected by VTA inactivation. Surprisingly, two effects of LC-TH+ photoactivation are sensitive to hippocampal D1/D5 receptor blockade and resistant to adrenoceptors blockade – memory enhancement and long lasting potentiation of synaptic transmission in CA1 ex vivo. Thus, LC-TH+ neurons can mediate post-encoding memory enhancement in a manner consistent with possible co-release of dopamine in hippocampus. PMID:27602521

  11. Modo-UG, a marsupial nonclassical MHC class I locus.

    Science.gov (United States)

    Gouin, Nicolas; Wright, April M; Miska, Katarzyna B; Parra, Zuly E; Samollow, Paul B; Baker, Michelle L; Miller, Robert D

    2006-06-01

    Modo-UG is a class I gene located in the MHC of the marsupial Monodelphis domestica, the gray, short-tailed opossum. Modo-UG is expressed as three alternatively spliced mRNA forms, all of which encode a transmembrane form with a short cytoplasmic tail that lacks phosphorylation sites typically found in classical class I molecules. The three alternative mRNAs would encode a full-length form, an isoform lacking the alpha2 domain, and one lacking both alpha2 and alpha3 domains. Genotyping both captive-bred and wild M. domestica from different geographic regions revealed no variation in the residues that make up Modo-UG's peptide-binding groove. Modo-UG's low polymorphism is contrasting to that of a nearby class I locus, Modo-UA1, which has a highly polymorphic peptide-binding region. Absence of functional polymorphism in Modo-UG is therefore not a general feature of opossum class I genes but the result of negative selection. Modo-UG is the first MHC linked marsupial class I to be described that appears to clearly have nonclassical features.

  12. Copy-Number Gains of HUWE1 Due to Replication- and Recombination-Based Rearrangements

    Science.gov (United States)

    Froyen, Guy; Belet, Stefanie; Martinez, Francisco; Santos-Rebouças, Cíntia Barros; Declercq, Matthias; Verbeeck, Jelle; Donckers, Lene; Berland, Siren; Mayo, Sonia; Rosello, Monica; Pimentel, Márcia Mattos Gonçalves; Fintelman-Rodrigues, Natalia; Hovland, Randi; Rodrigues dos Santos, Suely; Raymond, F. Lucy; Bose, Tulika; Corbett, Mark A.; Sheffield, Leslie; van Ravenswaaij-Arts, Conny M.A.; Dijkhuizen, Trijnie; Coutton, Charles; Satre, Veronique; Siu, Victoria; Marynen, Peter

    2012-01-01

    We previously reported on nonrecurrent overlapping duplications at Xp11.22 in individuals with nonsyndromic intellectual disability (ID) harboring HSD17B10, HUWE1, and the microRNAs miR-98 and let-7f-2 in the smallest region of overlap. Here, we describe six additional individuals with nonsyndromic ID and overlapping microduplications that segregate in the families. High-resolution mapping of the 12 copy-number gains reduced the minimal duplicated region to the HUWE1 locus only. Consequently, increased mRNA levels were detected for HUWE1, but not HSD17B10. Marker and SNP analysis, together with identification of two de novo events, suggested a paternally derived intrachromosomal duplication event. In four independent families, we report on a polymorphic 70 kb recurrent copy-number gain, which harbors part of HUWE1 (exon 28 to 3′ untranslated region), including miR-98 and let-7f-2. Our findings thus demonstrate that HUWE1 is the only remaining dosage-sensitive gene associated with the ID phenotype. Junction and in silico analysis of breakpoint regions demonstrated simple microhomology-mediated rearrangements suggestive of replication-based duplication events. Intriguingly, in a single family, the duplication was generated through nonallelic homologous recombination (NAHR) with the use of HUWE1-flanking imperfect low-copy repeats, which drive this infrequent NAHR event. The recurrent partial HUWE1 copy-number gain was also generated through NAHR, but here, the homologous sequences used were identified as TcMAR-Tigger DNA elements, a template that has not yet been reported for NAHR. In summary, we showed that an increased dosage of HUWE1 causes nonsyndromic ID and demonstrated that the Xp11.22 region is prone to recombination- and replication-based rearrangements. PMID:22840365

  13. Polymorphisms in steroid hormone biosynthesis genes and risk of breast cancer and fibrocystic breast conditions in Chinese women.

    Science.gov (United States)

    Sakoda, Lori C; Blackston, Christie; Doherty, Jennifer A; Ray, Roberta M; Lin, Ming Gang; Stalsberg, Helge; Gao, Dao Li; Feng, Ziding; Thomas, David B; Chen, Chu

    2008-05-01

    Common variants in genes encoding for key enzymes involved in steroidogenesis may alter sex steroid hormone levels, thereby influencing susceptibility to breast carcinoma and related conditions. In a case-control study of Chinese women, we examined genotypes of the CYP11A1 pentanucleotide [(TAAAA)n] repeat (D15S520), CYP17A1 rs743572, and HSD17B1 rs605059 polymorphisms in relation to the risk of breast cancer and fibrocystic breast conditions, comparing 615 women with breast cancer and 467 women with fibrocystic breast conditions separately with 879 women without clinical breast disease. We also evaluated whether these relationships differed by the presence of proliferation in the extratumoral epithelium or fibrocystic lesions, menopausal status, or body mass index. Only CYP11A1 genotype was related to breast cancer risk, with women homozygous for the 4-repeat allele, relative to those homozygous for the 6-repeat allele, at reduced risk (age-adjusted odds ratio, 0.58; 95% confidence interval, 0.37-0.91). There was some suggestion of a stronger inverse association for breast cancer with evidence of proliferation in the extratumoral epithelium than for breast cancer without extratumoral proliferation. Breast cancer risk associated with CYP11A1 genotype did not differ by menopausal status or body mass index level. No associations between CYP11A1, CYP17A1, and HSD17B1 genotypes and risk of fibrocystic breast conditions were observed. Our findings support the possibility that common allelic variation at the CYP11A1 D15S520 locus alters breast cancer risk in Chinese women.

  14. The influence of message appeal, environmental hyperopia, and environmental locus of control on green policy communication

    National Research Council Canada - National Science Library

    Lee, Yu-Kang

    2013-01-01

      In this paper, the author examined the message appeal in green policy communication by clarifying the moderating roles of environmental hyperopia and individual differences in environmental locus of control...

  15. [Polymorphism of TPH gene T3792A locus in Han ethnic group of north China].

    Science.gov (United States)

    Wang, Bing; Wang, Bao-Jie; Ding, Mei; Pang, Hao; Zhang, Zhen; Guan, Hong-Yu; Lu, Hong-Tao

    2008-12-01

    To investigate the polymorphism of the TPH gene T3792A locus in Han ethnic group of north China and its application value in forensic science. The polymorphism of T3792A locus of the TPH gene was analyzed by the ASPCR of blood samples from 173 unrelated individuals of north Chinese Han population. The distribution of the T3792A locus polymorphism of the TPH gene in Han ethnic group of north China followed the Hardy-Weinberg law, with the allele A and T gene frequency of 0.486 and 0.514, respectively. The TPH gene T3792A locus shows a very good genetic polymorphism, and may be applied to individual identification and paternity testing.

  16. Effects of Locus of Control and Type of Reinforcement on Programmed Instruction Performance of Adolescent Boys

    Science.gov (United States)

    Gregory, Mary K.

    1976-01-01

    Students with an internal locus of control functioned well under a variety of conditions while students needing extrinsic reinforcement functioned well only when feedback was provided by the experimenter. (MM)

  17. Impact of self-esteem, locus of control and gender on attitude ...

    African Journals Online (AJOL)

    esteem scale developed by Adanijo and Oyefeso (1986), locus of control scale developed by Craig, Franklin and Andrew (1981) and attitude towards child adoption and adoptive parent questionnaire designed by the researchers. All measures used ...

  18. Inbreeding depression in a parasitoid wasp with single-locus complementary sex determination

    National Research Council Canada - National Science Library

    Vayssade, Chloé; de Fazio, Céline; Quaglietti, Bastien; Auguste, Alexandra; Ris, Nicolas; Fauvergue, Xavier

    2014-01-01

    .... Although recessive deleterious alleles that are expressed in males should be purged, an alternative form of inbreeding depression exists in species with single-locus complementary sex determination (sl-CSD...

  19. Inbreeding Depression in a Parasitoid Wasp with Single-Locus Complementary Sex Determination: e97733

    National Research Council Canada - National Science Library

    Chloé Vayssade; Céline de Fazio; Bastien Quaglietti; Alexandra Auguste; Nicolas Ris; Xavier Fauvergue

    2014-01-01

    .... Although recessive deleterious alleles that are expressed in males should be purged, an alternative form of inbreeding depression exists in species with single-locus complementary sex determination (sl-CSD...

  20. Health Locus of Control and Health Seeking Behaviour. The Ghanaian Experience

    Directory of Open Access Journals (Sweden)

    Isaac Acheampong Sarfo

    2016-08-01

    Full Text Available This study sought to examine the relationship between health locus of control orientation and health seeking behaviour, using the Ghanaian experience as a case in point. The study used the general population in the new Juaben Municipality as respondents based on their multiethnic backgrounds. Findings revealed that health locus of control did not mediate significantly between their illnesses and respective health seeking behaviour. There were various sociocultural factors like the collectivist cultural system that made a categorization of locus of control of any individual quite difficult. It was concluded that the cultural practices of respondents were the major determinant of individual’s behavior. In addition, the health system as practiced over a long period of time did not allow enough room for patients to make choices in terms of illness behaviour, a situation that affected their health locus of control behaviour.

  1. Genetic heterogeneity in benign familial neonatal convulsions: Identification of a new locus on chromosome 8q

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, T.B.; Leach, R.J.; O' Connell, P.; Ryan, S.G. (Univ. of Texas Health Science Center, San Antonio, TX (United States)); Ward, K. (Univ. of Utah Medical School, Salt Lake City, UT (United States))

    1993-09-01

    The syndrome of benign familial neonatal convulsions (BFNC) is a rare autosomal dominant disorder characterized by unprovoked seizures in the first weeks of life. One locus for BFNC has been mapped to chromosome 20 in several pedigrees, but the authors have excluded linkage to chromosome 20 in one large kindred. In order to identify this novel BFNC locus, dinucleotide repeat markers distributed throughout the genome were used to screen this family. Maximum pairwise LOD scores of 4.43 were obtained with markers D8S284 and D8S256 on chromosome 8q. Multipoint analysis placed the BFNC locus in the interval spanned by D8S198-D8S274. This study establishes the presence of a new BFNC locus and confirms genetic heterogeneity of this disorder. 26 refs., 3 figs., 1 tab.

  2. Understanding the role of locus of control in consultative decision-making: a case study

    OpenAIRE

    Selart, Marcus

    2005-01-01

    Purpose: The study aims at clarifying whether locus of control may act as a bias in organisational decision-making or not. Design/methodology/approach: Altogether 44 managers working at Skanska (a Swedish multinational construction company) participated in the study. They were asked to complete a booklet including a locus of control test and a couple of decision tasks. The latter were based on case scenarios reflecting strategic issues relevant for consultative/ participative decision-making....

  3. Molecular Characterization Of The Vernalization Locus VRN1 In Perennial Ryegrass

    DEFF Research Database (Denmark)

    Asp, Torben; Byrne, Stephen; Andersen, Jeppe R

    in perennial ryegrass (Lolium perenne). Two allelic BAC clones of the VRN1 locus from the two genotypes Veyo and Falster with contrasting vernalization requirements were identified, sequenced, and characterized. The region surrounding the VRN1 locus in perennial ryegrass showed micro...... vernalization requirement. Our findings suggest that the 8.6kb region in the first intron of the VRN1 gene is an important regulatory region for vernalization response in perennial ryegrass....

  4. Relationship between Dental Anxiety and Health Locus of Control among Physiotherapy Students

    Directory of Open Access Journals (Sweden)

    Pooja Agarwal

    2013-01-01

    Materials & Method: A total of 152 students participated in the study. Dental anxiety was assessed using the 5 item Modified Dental Anxiety Scale (MDAS and Locus of Control was assessed using the 18 item Multidimensional Health Locus of Control (MHLC scale. Results: A Statistically significant positive correlation was found between the internal dimension of MHLC and dental anxiety. Conclusions: HLC was found to play an important role in predicting the dental anxiety among physiotherapy students.

  5. Health locus of control: Its relationship with medication adherence and medication wastage.

    Science.gov (United States)

    West, Lorna Marie; Borg Theuma, Ruth; Cordina, Maria

    2017-12-09

    Non-adherence is a significant factor contributing to medication wastage. Whilst there is some evidence on the influence of patients' health locus of control in relation to adherence, there has been little inquiry into its relationship with mediation wastage. To determine the relationship between medication adherence and health locus of control as well as medication wastage and health locus of control in patients with chronic conditions. Outpatients having a diagnosis of asthma, cardiovascular conditions, or diabetes participated in a cross-sectional study employing a self-administered questionnaire. The questionnaire determined presence of unused medication (wastage), adherence using 'Tool for Adherence Behaviour Screening' (TABS), and health locus of control using 'Multidimensional Health Locus of Control' (MHLC) scale Form C. Logistic regression was performed to ascertain the effects of MHLC and demographics in relation to adherence and wastage. MHLC beliefs were divided into 8 types of health locus of control. One-Way ANOVA was used to assess differences between conditions and belief types. P-values ≤ .05 were considered significant. There were 330 patients recruited (58% male; age, mean±(SD): 61 ± 15 years; 110 asthma, 110 cardiovascular, 110 diabetes). In terms of health locus of control, females had higher 'doctors' beliefs (p = .054) and significantly lower 'other people' beliefs (p = adherence. Lower 'doctors' beliefs and higher 'other people' beliefs were significantly associated with wastage (p = adherence (p = medication, followed by 'pure internal' believers. 'Pure powerful others external' had the highest presence of unused medication. Healthcare professionals should take into account patients' health locus of control beliefs whilst conducting an intervention with patients; this can impact positively medication adherence and minimisation of medication wastage. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. The Interrelationship among Locus of Control, Sexual Satisfaction and Marital Satisfaction

    OpenAIRE

    Askari Asgharianji; Kamo Vardanyan; Shokouh Navabinejad

    2015-01-01

    The primary goal of the present study is to examine the interrelationships among locus of control, sexual satisfaction and marital satisfaction. In the current study, a sample which was composed of 200 married persons was investigated. Research tools include locus of control, sexual satisfaction and marital satisfaction. For data analysis, correlation and independent hierarchical multiple regression analyses were used to determine the relationships between the predictor variables and criterio...

  7. Buffering Role of Locus of Control on Stress among the College/University Teachers of Bahawalpur

    OpenAIRE

    Aqeel Ahmad Khan; Raheela Shahid; Muhammad Saleem

    2012-01-01

    The present research is aimed to ascertain the role of locus of control in mediating or coping on various degree/levels of stress among the college/university teachers of Bahawalpur. For that purpose a sample of N=200 male/female college/university teacherswas selected by convenient sampling. Research tools, Locus of control by Julian Rotter (1966) and Stress questionnaire by International Stress Management Association UK, (2009) were administered for data collection. After the collection of ...

  8. High-Density SNP Genotyping to Define β-Globin Locus Haplotypes

    OpenAIRE

    Liu, Li; Muralidhar, Shalini; Singh, Manisha; Sylvan, Caprice; Kalra, Inderdeep S.; Quinn, Charles T.; Onyekwere, Onyinye C.; Pace, Betty S.

    2008-01-01

    Five major β-globin locus haplotypes have been established in individuals with sickle cell disease (SCD) from the Benin, Bantu, Senegal, Cameroon, and Arab-Indian populations. Historically, β-haplotypes were established using restriction fragment length polymorphism (RFLP) analysis across the β-locus, which consists of five functional β-like globin genes located on chromosome 11. Previous attempts to correlate these haplotypes as robust predictors of clinical phenotypes observed in SCD have n...

  9. Locus coeruleus damage and noradrenaline reductions in multiple sclerosis and experimental autoimmune encephalomyelitis.

    Science.gov (United States)

    Polak, Paul E; Kalinin, Sergey; Feinstein, Douglas L

    2011-03-01

    The endogenous neurotransmitter noradrenaline exerts anti-inflammatory and neuroprotective effects in vitro and in vivo. Several studies report that noradrenaline levels are altered in the central nervous system of patients with multiple sclerosis and rodents with experimental autoimmune encephalomyelitis, which could contribute to pathology. Since the major source of noradrenaline are neurons in the locus coeruleus, we hypothesized that alterations in noradrenaline levels are a consequence of stress or damage to locus coeruleus neurons. In C57BL/6 mice immunized with myelin oligodendrocyte glycoprotein peptide 35-55 to develop chronic disease, cortical and spinal cord levels of noradrenaline were significantly reduced versus control mice. Immunohistochemical staining revealed increased astrocyte activation in the ventral portion of the locus coeruleus in immunized mice. The immunized mice showed neuronal damage in the locus coeruleus detected by a reduction of average cell size of tyrosine hydroxylase stained neurons. Analysis of the locus coeruleus of multiple sclerosis and control brains showed a significant increase in astrocyte activation, a reduction in noradrenaline levels, and neuronal stress indicated by hypertrophy of tyrosine hydroxylase stained cell bodies. However, the magnitude of these changes was not correlated with extent of demyelination or of cellular infiltrates. Together these findings demonstrate the presence of inflammation and neuronal stress in multiple sclerosis as well as in experimental autoimmune encephalomyelitis. Since reduced noradrenaline levels could be permissive for increased inflammation and neuronal damage, these results suggest that methods to raise noradrenaline levels or increase locus coeruleus function may be of benefit in treating multiple sclerosis.

  10. Locus of control in maltreated children: the impact of attachment and cumulative trauma

    Directory of Open Access Journals (Sweden)

    Antonio Roazzi

    2016-01-01

    Full Text Available Abstract Up until now research studies carried out on abused children have rarely taken in consideration the impact of maltreatment on the locus of control; furthermore results concerning the distribution of attachment internal models in this population are inconclusive. In addition, no study has ever taken in consideration the differential role of attachment and time of exposure to stress in the formation of attributive styles. This research work involved 60 maltreated children and 100 controls with the purpose of evaluating the associations between their attachment and age as for their locus of control. Internal Working Models were assessed by SAT and locus of control by the Nowicki-Strickland Scale. Results highlight mainly external locus of control and disorganized and avoidant IWMs in abused children. Furthermore, age was more predictive than attachment for locus of control. By contrast, in the control group at both age taken in consideration attachment was predictive of locus of control. Results are discussed in terms of problematic symptoms associated to maltreatment.

  11. Comparing health locus of control in patients with Spasmodic Dysphonia, Functional Dysphonia and Nonlaryngeal Dystonia.

    Science.gov (United States)

    Haselden, Karen; Powell, Theresa; Drinnan, Mike; Carding, Paul

    2009-11-01

    Locus of Control (LoC) refers to an individuals' perception of whether they are in control of life events. Health Locus of Control refers to whether someone feels they have influence over their health. Health Locus of Control has not been studied in any depth in voice-disordered patients. The objective of this study was to examine Health Locus of Control in three patient groups: (1) Spasmodic Dysphonia, (2) Functional Dysphonia and (3) a nondysphonic group with Nonlaryngeal Dystonia. LoC was measured and compared in a total of 57 patients using the Multidimensional Health Locus of Control Scales (diagnostic specific) Form C. Internal, Chance, and Powerful others LoC were measured and comparisons were made using one-way analysis of variance. Contrary to expectations Internal LoC was found to be significantly higher in the Functional Dysphonia group when compared to the other two groups. There was no significant difference between the groups in Chance or Powerful others LoC. The two organic groups, Spasmodic Dysphonia and Nonlaryngeal Dystonia, were more alike in Internal Health Locus of Control than the Functional Dysphonia group. The diagnostic nature of the groups was reflected in their LoC scores rather than their voice loss. These results contribute to the debate about the etiology of Spasmodic Dysphonia and will be of interest to those involved in the psychology of voice and those managing voice-disordered patients.

  12. Social capital, political trust, and health locus of control: a population-based study.

    Science.gov (United States)

    Lindström, Martin

    2011-02-01

    To investigate the association between political trust in the Riksdag and lack of belief in the possibility to influence one's own health (external locus of control), taking horizontal trust into account. The 2008 public health survey in Skåne is a cross-sectional postal questionnaire study with a 55% participation rate. A random sample of 28,198 persons aged 18-80 years participated. Logistic regression models were used to investigate the associations between political trust in the Riksdag (an aspect of vertical trust) and lack of belief in the possibility to influence one's own health (external locus of control). The multiple regression analyses included age, country of birth, education, and horizontal trust in other people. A 33.7% of all men and 31.8% of all women lack internal locus of control. Low (external) health locus of control is more common in higher age groups, among people born outside Sweden, with lower education, low horizontal trust, low political trust, and no opinion concerning political trust. Respondents with not particularly strong political trust, no political trust at all and no opinion have significantly higher odds ratios of external locus of control throughout the multiple regression analyses. Low political trust in the Riksdag seems to be independently associated with external health locus of control.

  13. The relationship between the perception of own locus of control and aggression of adolescent boys

    Directory of Open Access Journals (Sweden)

    Lettie Breet

    2010-01-01

    Full Text Available Aggression is increasingly seen in most parts of South African society. Aggressive behaviour of boys in secondary school often results from frustrations caused by perceived high expectations of others regarding the role, locus of control, and personality of boys. Locus of control plays an important role in a person's perception concerning a situation and possible reactions to what is happening, or should be happening. A 56-item questionnaire, based on Rotter's "Locus of control" questionnaire, and the DIAS Scale were used. The questionnaire was completed by 440 boys in Grades 9, 10, and 11. Various factor, item and differential statistical analyses were conducted. Three constructs were identified, i.e. physical, verbal, and indirect aggression. Results indicated that locus of control has a significant influence on verbal and indirect aggression. The differential analysis indicated that contextual variables (language of tuition, age, and grade play a significant, but not substantial, role in aggression. Furthermore, boys with an internal locus of control are significantly and substantially less aggressive than boys with an external locus of control, with respect to physical, verbal and indirect aggression.

  14. Locus heterogeneity disease genes encode proteins with high interconnectivity in the human protein interaction network

    Directory of Open Access Journals (Sweden)

    Benjamin eKeith

    2014-12-01

    Full Text Available Mutations in genes potentially lead to a number of genetic diseases with differing severity. These disease genes have been the focus of research in recent years showing that the disease gene population as a whole is not homogeneous, and can be categorised according to their interactions. Locus heterogeneity describes a single disorder caused by mutations in different genes each acting individually to cause the same disease. Using datasets of experimentally derived human disease genes and protein interactions, we created a protein interaction network to investigate the relationships between the products of genes associated with a disease displaying locus heterogeneity, and use network parameters to suggest properties that distinguish these disease genes from the overall disease gene population. Through the manual curation of known causative genes of 100 diseases displaying locus heterogeneity and 397 single-gene Mendelian disorders, we use network parameters to show that our locus heterogeneity network displays distinct properties from the global disease network and a Mendelian network. Using the global human proteome, through random simulation of the network we show that heterogeneous genes display significant interconnectivity. Further topological analysis of this network revealed clustering of locus heterogeneity genes that cause identical disorders, indicating that these disease genes are involved in similar biological processes. We then use this information to suggest novel genes that may also contribute to diseases with locus heterogeneity.

  15. Locus of control and peer relationships among Caucasian, Hispanic, Asian, and African American adolescents.

    Science.gov (United States)

    Kang, Hannah Soo; Chang, Kyle Edward; Chen, Chuansheng; Greenberger, Ellen

    2015-01-01

    Past research has shown that locus of control plays an important role in a wide range of behaviors, such as academic achievement and positive social behaviors. However, little is known about whether locus of control plays the same role in minority adolescents' peer relationships. The current study examined ethnic differences in the associations between locus of control and peer relationships in early adolescence using samples from the Early Childhood Longitudinal Study (ECLS-K: 5,612 Caucasian, 1,562 Hispanic, 507 Asian, and 908 African-American adolescents) and the National Education Longitudinal Study (NELS: 8,484 Caucasian, 1,604 Hispanic, and 860 Asian, and 1,228 African American adolescents). Gender was approximately evenly split in both samples. The results from the two datasets were highly consistent. Significant interactions between ethnicity and locus of control indicated that having a more internal locus of control was particularly important for Caucasian students' peer relationships (ECLS-K) and social status (NELS), but less so for Asian, Hispanic, and African American students. Our findings suggest that the role of locus of control in peer relationship is contingent upon culture.

  16. The unusual S locus of Leavenworthia is composed of two sets of paralogous loci.

    Science.gov (United States)

    Chantha, Sier-Ching; Herman, Adam C; Castric, Vincent; Vekemans, Xavier; Marande, William; Schoen, Daniel J

    2017-12-01

    The Leavenworthia self-incompatibility locus (S locus) consists of paralogs (Lal2, SCRL) of the canonical Brassicaceae S locus genes (SRK, SCR), and is situated in a genomic position that differs from the ancestral one in the Brassicaceae. Unexpectedly, in a small number of Leavenworthia alabamica plants examined, sequences closely resembling exon 1 of SRK have been found, but the function of these has remained unclear. BAC cloning and expression analyses were employed to characterize these SRK-like sequences. An SRK-positive Bacterial Artificial Chromosome clone was found to contain complete SRK and SCR sequences located close by one another in the derived genomic position of the Leavenworthia S locus, and in place of the more typical Lal2 and SCRL sequences. These sequences are expressed in stigmas and anthers, respectively, and crossing data show that the SRK/SCR haplotype is functional in self-incompatibility. Population surveys indicate that S loci possess such alleles. An ancestral translocation or recombination event involving SRK/SCR and Lal2/SCRL likely occurred, together with neofunctionalization of Lal2/SCRL, and both haplotype groups now function as Leavenworthia S locus alleles. These findings suggest that S locus alleles can have distinctly different evolutionary origins. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  17. Searching for a major locus for male pattern baldness (MPB)

    Energy Technology Data Exchange (ETDEWEB)

    Anker, R.; Eisen, A.Z.; Donis-Keller, H. [Washington Univ. School of Medicine, St. Louis, MO (United States)

    1994-09-01

    Male pattern baldness (MPB) is a common trait in post-pubertal males. Approximately 50% of adult males present some degree of MPB by age 50. According to the classification provided by Hamilton in 1951 and modified by Norwood in 1975, the trait itself is a continuum that ranges from mild (Type I) to severe (Type VII) cases. In addition, there is extensive variability for the age of onset. The role of androgens in allowing the expression of this trait in males has been well established. This phenotype is uncommonly expressed in females. The high prevalence of the trait, the distribution of MPB as a continuous trait, and several non-allelic mutations identified in the mouse capable of affecting hair pattern, suggest that MPB is genetically heterogeneous. In order to reduce the probability of multiple non-allelic MPB genes within a pedigree, we selected 9 families in which MPB appears to segregate exclusively through the paternal lineage as compared to bilineal pedigrees. There are 32 males expressing this phenotype and females are treated as phenotype unknown. In general, affected individuals expressed the trait before 30 years of age with a severity of at least Type III or IV. We assumed an autosomal dominant model, with a gene frequency of 1/20 for the affected allele, and 90% penetrance. Simulation studies using the SLINK program with these pedigrees showed that these families would be sufficient to detect linkage under the assumption of a single major locus. If heterogeneity is present, the current resource does not have sufficient power to detect linkage at a statistically significant level, although candidate regions of the genome could be identified for further studies with additional pedigrees. Using 53 highly informative microsatellite markers, and a subset of 7 families, we have screened 30% of the genome. This search included several regions where candidate genes for MPB are located.

  18. Molecular characterization of the singed wings locus of Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Boykova Tatiana

    2004-06-01

    Full Text Available Abstract Background Hormones frequently guide animal development via the induction of cascades of gene activities, whose products further amplify an initial hormonal stimulus. In Drosophila the transformation of the larva into the pupa and the subsequent metamorphosis to the adult stage is triggered by changes in the titer of the steroid hormone 20-hydroxyecdysone. singed wings (swi is the only gene known in Drosophila melanogaster for which mutations specifically interrupt the transmission of the regulatory signal from early to late ecdysone inducible genes. Results We have characterized singed wings locus, showing it to correspond to EG:171E4.2 (CG3095. swi encodes a predicted 68.5-kDa protein that contains N-terminal histidine-rich and threonine-rich domains, a cysteine-rich C-terminal region and two leucine-rich repeats. The SWI protein has a close homolog in D. melanogaster, defining a new family of SWI-like proteins, and is conserved in D. pseudoobscura. A lethal mutation, swit476, shows a severe disruption of the ecdysone pathway and is a C>Y substitution in one of the two conserved CysXCys motifs that are common to SWI and the Drosophila Toll-4 protein. Conclusions It is not entirely clear from the present molecular analysis how the SWI protein may function in the ecdysone induced cascade. Currently all predictions agree in that SWI is very unlikely to be a nuclear protein. Thus it probably exercises its control of "late" ecdysone genes indirectly. Apparently the genetic regulation of ecdysone signaling is much more complex then was previously anticipated.

  19. The locus of impairment in English developmental letter position dyslexia.

    Science.gov (United States)

    Kezilas, Yvette; Kohnen, Saskia; McKague, Meredith; Castles, Anne

    2014-01-01

    Many children with reading difficulties display phonological deficits and struggle to acquire non-lexical reading skills. However, not all children with reading difficulties have these problems, such as children with selective letter position dyslexia (LPD), who make excessive migration errors (such as reading slime as "smile"). Previous research has explored three possible loci for the deficit - the phonological output buffer, the orthographic input lexicon, and the orthographic-visual analysis stage of reading. While there is compelling evidence against a phonological output buffer and orthographic input lexicon deficit account of English LPD, the evidence in support of an orthographic-visual analysis deficit is currently limited. In this multiple single-case study with three English-speaking children with developmental LPD, we aimed to both replicate and extend previous findings regarding the locus of impairment in English LPD. First, we ruled out a phonological output buffer and an orthographic input lexicon deficit by administering tasks that directly assess phonological processing and lexical guessing. We then went on to directly assess whether or not children with LPD have an orthographic-visual analysis deficit by modifying two tasks that have previously been used to localize processing at this level: a same-different decision task and a non-word reading task. The results from these tasks indicate that LPD is most likely caused by a deficit specific to the coding of letter positions at the orthographic-visual analysis stage of reading. These findings provide further evidence for the heterogeneity of dyslexia and its underlying causes.

  20. The locus of impairment in English developmental letter position dyslexia

    Directory of Open Access Journals (Sweden)

    Yvette eKezilas

    2014-06-01

    Full Text Available Many children with reading difficulties display phonological deficits and struggle to acquire nonlexical reading skills. However, not all children with reading difficulties have these problems, such as children with selective Letter Position Dyslexia (LPD, who make excessive migration errors (such as reading slime as ‘smile’. Previous research has explored three possible loci for the deficit – the phonological output buffer, the orthographic input lexicon, and the orthographic-visual analysis stage of reading. While there is compelling evidence against a phonological output buffer and orthographic input lexicon deficit account of English LPD, the evidence in support of an orthographic-visual analysis deficit is currently limited. In this multiple single-case study with three English speaking children with developmental LPD we aimed to both replicate and extend previous findings regarding the locus of impairment in English LPD. First, we ruled out a phonological output buffer and an orthographic input lexicon deficit by administering tasks that directly assess phonological processing and lexical guessing. We then went on to directly assess whether or not children with LPD have an orthographic-visual analysis deficit by modifying two tasks that have previously been used to localize processing at this level: a same-different decision task and a nonword reading task. The results from these tasks indicate that LPD is most likely caused by a deficit specific to the coding of letter positions at the orthographic-visual analysis stage of reading. These findings provide further evidence for the heterogeneity of dyslexia and its underlying causes.