Teaching the Fluctuation Test "In Silico" by Using Mutate: A Program to Distinguish between the Adaptive and Spontaneous Mutation Hypotheses

Science.gov (United States)

Carvajal-Rodriguez, Antonio

2012-01-01

Mutate is a program developed for teaching purposes to impart a virtual laboratory class for undergraduate students of Genetics in Biology. The program emulates the so-called fluctuation test whose aim is to distinguish between spontaneous and adaptive mutation hypotheses in bacteria. The plan is to train students in certain key multidisciplinary…

Molecular nature of X-ray-induced mutations compared with that of spontaneous ones in human c-hprt gene integrated into mammalian chromosomal DNA

International Nuclear Information System (INIS)

Kimura, Hiroshi; Kato, Takesi.

1992-01-01

X-ray-induced mutations were analysed at molecular levels in comparison with spontaneous mutations. Altered sequences were determined tentatively of 30 independent X-ray-induced mutations in a cDNA of the human hprt gene which was integrated into mammalian chromosome as a part of a shuttle vector. Mutations consisted of base substitutions (37 %), frameshifts (27 %), deletions (27 %) and others (10 %). All these mutational events were distributed randomly over the gene without there being hot spots. The spectrum and distribution of X-ray-induced mutations resembled those of spontaneous mutations. Among base substitutions, transversions were predominant and base substitution mutations occurred more at A:T sites than at G:C sites, which is also the case in spontaneous mutations. Most of the frameshift and deletion mutations induced by X-rays, as well as those spontaneously arising, were characterized by the existence of short direct repeats of several identical bases in a row at the sites of the mutations. A slippage misalignment mechanism in replication well accounts for the generation of these classes of mutations. Judging from the data accumulated so far, it can be concluded that X-ray-induced mutations at molecular levels are similar to those spontaneously occurring. (author)

Teaching the fluctuation test in silico by using mutate: a program to distinguish between the adaptive and spontaneous mutation hypotheses.

Science.gov (United States)

Carvajal-Rodríguez, Antonio

2012-07-01

Mutate is a program developed for teaching purposes to impart a virtual laboratory class for undergraduate students of Genetics in Biology. The program emulates the so-called fluctuation test whose aim is to distinguish between spontaneous and adaptive mutation hypotheses in bacteria. The plan is to train students in certain key multidisciplinary aspects of current genetics such as sequence databases, DNA mutations, and hypothesis testing, while introducing the fluctuation test. This seminal experiment was originally performed studying Escherichia coli resistance to the infection by bacteriophage T1. The fluctuation test initiated the modern bacterial genetics that 25 years later ushered in the era of the recombinant DNA. Nowadays we know that some deletions in fhuA, the gene responsible for E. coli membrane receptor of T1, could cause the E. coli resistance to this phage. For the sake of simplicity, we will introduce the assumption that a single mutation generates the resistance to T1. During the practical, the students use the program to download some fhuA gene sequences, manually introduce some stop codon mutations, and design a fluctuation test to obtain data for distinguishing between preadaptative (spontaneous) and induced (adaptive) mutation hypotheses. The program can be launched from a browser or, if preferred, its executable file can be downloaded from http://webs.uvigo.es/acraaj/MutateWeb/Mutate.html. It requires the Java 5.0 (or higher) Runtime Environment (freely available at http://www.java.com). Copyright © 2012 Wiley Periodicals, Inc.

EFFECT OF THE ANTIMUTAGENS VANILLIN AND CINNAMALDEHYDE ON THE SPONTANEOUS MUTATION SPECTRA OF SALMONELLA TA104

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Effect of the Antimutagens Vanillin and Cinnamaldehyde on the / Spontaneous Mutation Spectra of Salmonella TAlO4 Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that, when added to assay plates, reduced the spontaneous mutant frequency in Salmonella typhi...

The spontaneous chlorophyll mutation frequency in barley

DEFF Research Database (Denmark)

Jørgensen, Jørgen Helms; Jensen, Hans Peter

1986-01-01

A total of 1866 barley plants were progeny tested in the greenhouse. Twenty-five plants segregated for newly arisen, spontaneous chlorophyll mutant genes. Among the total of 470,129 seedlings screened there were 79 mutants (1.7 .+-. 0.6 .times. 10-4). The data are added to data from three similar...... materials and the resulting estimate of the chlorophyll mutant frequency is 1.6 .times. 10-4 in about 1.43 million seedlings. The estimate of the chlorophyll mutation rate per generation is close to 67.3 .times. 10-4 per diploid genome or in the order of 6 .times. 10-7 per locus and haploid genome....

A Mutator Phenotype Promoting the Emergence of Spontaneous Oxidative Stress-Resistant Mutants in Campylobacter jejuni.

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Dai, Lei; Sahin, Orhan; Tang, Yizhi; Zhang, Qijing

2017-12-15

Campylobacter jejuni is a leading cause of foodborne illnesses worldwide. As a microaerophilic organism, C. jejuni must be able to defend against oxidative stress encountered both in the host and in the environment. How Campylobacter utilizes a mutation-based mechanism for adaptation to oxidative stress is still unknown. Here we present a previously undescribed phenotypic and genetic mechanism that promotes the emergence of oxidative stress-resistant mutants. Specifically, we showed that a naturally occurring mutator phenotype, resulting from a loss of function mutation in the DNA repair enzyme MutY, increased oxidative stress resistance (OX R ) in C. jejuni We further demonstrated that MutY malfunction did not directly contribute to the OX R phenotype but increased the spontaneous mutation rate in the peroxide regulator gene perR , which functions as a repressor for multiple genes involved in oxidative stress resistance. Mutations in PerR resulted in loss of its DNA binding function and derepression of PerR-controlled oxidative stress defense genes, thereby conferring an OX R phenotype and facilitating Campylobacter survival under oxidative stress. These findings reveal a new mechanism that promotes the emergence of spontaneous OX R mutants in bacterial organisms. IMPORTANCE Although a mutator phenotype has been shown to promote antibiotic resistance in many bacterial species, little is known about its contribution to the emergence of OX R mutants. This work describes the link between a mutator phenotype and the enhanced emergence of OX R mutants as well as its underlying mechanism involving DNA repair and mutations in PerR. Since DNA repair systems and PerR are well conserved in many bacterial species, especially in Gram positives, the same mechanism may operate in multiple bacterial species. Additionally, we developed a novel method that allows for rapid quantification of spontaneous OX R mutants in a bacterial population. This method represents a technical

Induction of spontaneous and UV-induced mutations during commitment to meiosis in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Machida, I.; Nakai, S.

1980-01-01

Inductions of reversions of nonsense, missense and frameshift-type mutations were investigated in a diploid cell population of Saccharomyces cerevisiae during commitment to meiosis, by using the medium-transfer technique from sporulation medium to vegetative medium. The yields of spontaneous reverse mutations obtained from the cells that were committed to different stages during meiosis were rather constant irrespective of the alleles tested, although the yields of both intergenic and intragenic recombinations markedly increased. The susceptibilities to UV-induced reverse mutations examined during commitment to meiosis were not changed appreciably. It is concluded that induction of base-change-type mutations in meiosis is not essentially different from that in mitosis. (orig.)

Effect of hsm mutations enhancing spontaneous mutability on induced mutagenesis and mitotic recombination in Saccharomyces cerevisiae yeast

International Nuclear Information System (INIS)

Fedorova, I.V.; Koval'tsova, S.V.; Ivanov, E.L.

1993-01-01

The authors have studied the effect of five nonallelic hms1-hms5 mutations on the incidence of direct mutations in loci ADE1 and ADE2, induced by UV-radiation, 6-hydroxyl-aminopurine, and nitrosomethylurea. All hms mutants were found to be insensitive to the lethal action of these mutagens. The frequency of UV-induced mutations to adenine dependence was increased in mutants hsm2-1, hsm3-1, hsm5-1, and particularly in hsm1-1, but remained unchanged in hsm4-1 compared to HSM. Mutagenesis induced by 6-hydroxylaminopurine was increased in all mutants studied, particularly in mutant hsm3-1. The authors did not detect any appreciable effect of hsm mutations on mutagenesis induced by nitrosomethylurea. The frequency of spontaneous mitotic conversion to prototrophy was studied in diploids heteroallelic to gene ADE2 and homo- and heterozygous for hsm mutations. Mutation hsm5-1 considerably increased the frequency of conversion for all heteroalleles studied, mutations hsm1-1 and hsm3-1 also considerably increased the conversion frequency, while mutations hsm1-1 and hsm4-1 had little effect on this process. The study of the properties of hsm mutations revealed joint genetic control of spontaneous and induced mutagenesis and recombination in yeast. The possibility that hsm mutations belong to the class of mutations impairing correction of unpaired DNA bases is discussed. 25 refs., 3 figs., 3 tabs

Effect of low dose gamma radiation on stamen-hairs of different clones of Tradescantia presenting variability in the frequency of spontaneous mutations

International Nuclear Information System (INIS)

Takahashi, C.S.

1976-01-01

Changes in the frequency of spontaneous somatic mutations were studied for three different clones of Tradescantia heterozygotes for flower and stamen-hair color keeping them under controlled or natural conditions in order to verify the effect of different environmental conditions on the different genotypes. The effect of inflorescence age on the variation of spontaneous mutations was studied choosing young and old inflorescences of a same plant. Low dose irradiation experiments were carried out with those clones to elucidate the radiation effects on the clones presenting changes in the frequency of spontaneous mutations. The chronic-and acute irradiation effects of low dose irradiation of the stamen-hair of Tradescantia were also studied. Results are discussed. (M.A.) [pt

The distribution of and complementation relationships between spontaneous X-linked recessive lethal mutations recovered from crossing long-term laboratory stocks of Drosophila melanogaster

International Nuclear Information System (INIS)

Schalet, A.P.

1986-01-01

Drosophila melanogaster males from a wild-type laboratory stock, were mated with virgin females of the M-6 stock, and 149 spontaneous independent non-mosaically transmitted, as well as 8 incidentally detected, mosaically transmitted, X-linked recessive lethal mutations were recovered from 95 704 F 2 cultures. 152 mutations were mapped over the entire length of the X-chromosome by complementation and/or crossover tests. Although there were far too few spontaneous mutations to make a meaningful comparison of relative mutability on a locus-by-locus basis, those loci displaying a relatively higher X-ray mutability, when taken as a group, tend to display a relatively higher spontaneous mutability, and those loci displaying a relatively lower X-ray mutability, when taken as a group, tend to display a relatively lower spontaneous mutability. (Auth.)

The Oenothera plastome mutator: effect of UV irradiation and nitroso-methyl urea on mutation frequencies

International Nuclear Information System (INIS)

Sears, B.B.; Sokalski, M.B.

1991-01-01

Oenothera plants homozygous for a recessive plastome mutator allele (pm) showed spontaneous mutation frequencies for plastome genes that are 200-fold higher than spontaneous levels. Mutations occurred at high frequencies in plants grown in the field, in a glasshouse, or as leaf tip cultures under fluorescent light, indicating that the plastome mutator activity is UV-independent. However, the chlorotic sectors became visible at an earlier stage of development when seedlings were irradiated, compared to seedlings that were not exposed to UV. These results imply that the rate of sorting-out was increased by the irradiation treatment, possibly due to a decrease in the effective number of multiplication-competent plastids, or a reduction in the extent of cytoplasmic mixing. Nitroso-methyl urea treatment of seeds had a dramatic effect on mutation frequency in both wild-type and plastome mutator samples. When the background mutation rates were low, the combination of the plastome mutator nucleus and the chemical mutagenesis treatment resulted in a synergistic effect, suggesting that the plastome mutator may involve a cpDNA repair pathway. (author)

A spontaneous body color mutation in Drosophila nappae (Diptera, Drosophilidae

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Augusto Santos Rampasso

2017-04-01

Full Text Available A yellow-bodied male appeared spontaneously in an isofemale line of Drosophila nappae established from a wild-caught female collected at the Forest Reserve of the Instituto de Biociências da Universidade de São Paulo, Cidade Universitária “Armando de Salles Oliveira”, São Paulo city, state of São Paulo, Brazil. This is the first mutation found in D. nappae, a species belonging to the tripunctata group. The yellow male was isolated and individually crossed to two wild-type (brown-colored virgin females from the same generation, yielding numerous offspring. All F1 individuals were wild-type, but the phenotypes yielded in the F2 generation were wild-type females, and both wild-type and yellow-bodied males. The latter yellow male mutants backcrossed with virgin wild-type F1 females yielded four phenotypes (brown-colored and yellow-colored flies of both sexes, indicating an inheritance pattern of X-linked recessive. Chi-square goodness of fit tests (α = 5% detected no significant differences among the number of flies per phenotype. The new mutation is hereby named yellow, due to its probable homology to a similar mutation with an identical inheritance pattern found in Drosophila melanogaster. Keywords: Recessive, São Paulo, Tripunctata group, X-linked, Yellow

The effects of MSH2 deficiency on spontaneous and radiation-induced mutation rates in the mouse germline

International Nuclear Information System (INIS)

Burr, Karen L-A.; Duyn-Goedhart, Annemarie van; Hickenbotham, Peter; Monger, Karen; Buul, Paul P.W. van; Dubrova, Yuri E.

2007-01-01

Mutation rates at two expanded simple tandem repeat (ESTR) loci were studied in the germline of mismatch repair deficient Msh2 knock-out mice. Spontaneous mutation rates in homozygous Msh2 -/- males were significantly higher than those in isogenic wild-type (Msh2 +/+ ) and heterozygous (Msh2 +/- ) mice. In contrast, the irradiated Msh2 -/- mice did not show any detectable increases in their mutation rate, whereas significant ESTR mutation induction was observed in the irradiated Msh2 +/+ and Msh2 +/- animals. Considering these data and the results of other publications, we propose that the Msh2-deficient mice possess a mutator phenotype in their germline and somatic tissues while the loss of a single Msh2 allele does not affect the stability of heterozygotes

Disheveled hair and ear (Dhe, a spontaneous mouse Lmna mutation modeling human laminopathies.

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Paul R Odgren

Full Text Available BACKGROUND: Investigations of naturally-occurring mutations in animal models provide important insights and valuable disease models. Lamins A and C, along with lamin B, are type V intermediate filament proteins which constitute the proteinaceous boundary of the nucleus. LMNA mutations in humans cause a wide range of phenotypes, collectively termed laminopathies. To identify the mutation and investigate the phenotype of a spontaneous, semi-dominant mutation that we have named Disheveled hair and ear (Dhe, which causes a sparse coat and small external ears in heterozygotes and lethality in homozygotes by postnatal day 10. FINDINGS: Genetic mapping identified a point mutation in the Lmna gene, causing a single amino acid change, L52R, in the coiled coil rod domain of lamin A and C proteins. Cranial sutures in Dhe/+ mice failed to close. Gene expression for collagen types I and III in sutures was deficient. Skulls were small and disproportionate. Skeletons of Dhe/+ mice were hypomineralized and total body fat was deficient in males. In homozygotes, skin and oral mucosae were dysplastic and ulcerated. Nuclear morphometry of cultured cells revealed gene dose-dependent blebbing and wrinkling. CONCLUSION: Dhe mice should provide a useful new model for investigations of the pathogenesis of laminopathies.

Spontaneous HBsAg loss in Korean patients: relevance of viral genotypes, S gene mutations, and covalently closed circular DNA copy numbers

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Kyun-Hwan Kim

2014-09-01

Full Text Available Background/AimsOccult HBV infection can persist following HBsAg loss and be transmitted, but the virological features are not well defined.MethodsHere we investigated 25 Korean patients who lost HBsAg during follow up, either spontaneously or subsequent to therapy.ResultsWhereas subtype adr (genotype C was found in 96% of HBsAg positive patients, 75 % of patients who lost HBsAg spontaneously were seemed to be infected with the ayw subtype with sequence similar to genotype D. Mutations in the major hydrophilic region (MHR of HBsAg were found in 7 patients who lost HBsAg spontaneously. The mutations include T123S, M125I/N, C139R, D144E, V177A, L192F, and W196L, some of which have not been reported before. Functional analysis via transfection experiments indicate that the C139R and D144E mutations drastically reduced HBsAg antigenicity, while the Y225del mutation found in one interferon-treated patient impaired HBsAg secretion.ConclusionsLack of detectable HBsAg in patient serum could be explained by low level of ccc DNA in liver tissue, low antigenicity of the surface protein, or its secretion defect.

Sexual selection on spontaneous mutations strengthens the between-sex genetic correlation for fitness.

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Allen, Scott L; McGuigan, Katrina; Connallon, Tim; Blows, Mark W; Chenoweth, Stephen F

2017-10-01

A proposed benefit to sexual selection is that it promotes purging of deleterious mutations from populations. For this benefit to be realized, sexual selection, which is usually stronger on males, must purge mutations deleterious to both sexes. Here, we experimentally test the hypothesis that sexual selection on males purges deleterious mutations that affect both male and female fitness. We measured male and female fitness in two panels of spontaneous mutation-accumulation lines of the fly, Drosophila serrata, each established from a common ancestor. One panel of mutation accumulation lines limited both natural and sexual selection (LS lines), whereas the other panel limited natural selection, but allowed sexual selection to operate (SS lines). Although mutation accumulation caused a significant reduction in male and female fitness in both the LS and SS lines, sexual selection had no detectable effect on the extent of the fitness reduction. Similarly, despite evidence of mutational variance for fitness in males and females of both treatments, sexual selection had no significant impact on the amount of mutational genetic variance for fitness. However, sexual selection did reshape the between-sex correlation for fitness: significantly strengthening it in the SS lines. After 25 generations, the between-sex correlation for fitness was positive but considerably less than one in the LS lines, suggesting that, although most mutations had sexually concordant fitness effects, sex-limited, and/or sex-biased mutations contributed substantially to the mutational variance. In the SS lines this correlation was strong and could not be distinguished from unity. Individual-based simulations that mimick the experimental setup reveal two conditions that may drive our results: (1) a modest-to-large fraction of mutations have sex-limited (or highly sex-biased) fitness effects, and (2) the average fitness effect of sex-limited mutations is larger than the average fitness effect of

Changes in the EV-A71 Genome through Recombination and Spontaneous Mutations: Impact on Virulence

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Madiiha Bibi Mandary

2018-06-01

Full Text Available Enterovirus 71 (EV-A71 is a major etiological agent of hand, foot and mouth disease (HFMD that mainly affects young children less than five years old. The onset of severe HFMD is due to neurological complications bringing about acute flaccid paralysis and pulmonary oedema. In this review, we address how genetic events such as recombination and spontaneous mutations could change the genomic organization of EV-A71, leading to an impact on viral virulence. An understanding of the recombination mechanism of the poliovirus and non-polio enteroviruses will provide further evidence of the emergence of novel strains responsible for fatal HFMD outbreaks. We aim to see if the virulence of EV-A71 is contributed solely by the presence of fatal strains or is due to the co-operation of quasispecies within a viral population. The phenomenon of quasispecies within the poliovirus is discussed to reflect viral fitness, virulence and its implications for EV-A71. Ultimately, this review gives an insight into the evolution patterns of EV-A71 by looking into its recombination history and how spontaneous mutations would affect its virulence.

The rate and effects of spontaneous mutation on fitness traits in the social amoeba, Dictyostelium discoideum.

Science.gov (United States)

Hall, David W; Fox, Sara; Kuzdzal-Fick, Jennie J; Strassmann, Joan E; Queller, David C

2013-07-08

We performed a mutation accumulation (MA) experiment in the social amoeba Dictyostelium discoideum to estimate the rate and distribution of effects of spontaneous mutations affecting eight putative fitness traits. We found that the per-generation mutation rate for most fitness components is 0.0019 mutations per haploid genome per generation or larger. This rate is an order of magnitude higher than estimates for fitness components in the unicellular eukaryote Saccharomyces cerevisiae, even though the base-pair substitution rate is two orders of magnitude lower. The high rate of fitness-altering mutations observed in this species may be partially explained by a large mutational target relative to S. cerevisiae. Fitness-altering mutations also may occur primarily at simple sequence repeats, which are common throughout the genome, including in coding regions, and may represent a target that is particularly likely to give fitness effects upon mutation. The majority of mutations had deleterious effects on fitness, but there was evidence for a substantial fraction, up to 40%, being beneficial for some of the putative fitness traits. Competitive ability within the multicellular slug appears to be under weak directional selection, perhaps reflecting the fact that slugs are sometimes, but not often, comprised of multiple clones in nature. Evidence for pleiotropy among fitness components across MA lines was absent, suggesting that mutations tend to act on single fitness components.

Assessing the contribution of the herpes simplex virus DNA polymerase to spontaneous mutations

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Leary Jeffry J

2002-05-01

Full Text Available Abstract Background The thymidine kinase (tk mutagenesis assay is often utilized to determine the frequency of herpes simplex virus (HSV replication-mediated mutations. Using this assay, clinical and laboratory HSV-2 isolates were shown to have a 10- to 80-fold higher frequency of spontaneous mutations compared to HSV-1. Methods A panel of HSV-1 and HSV-2, along with polymerase-recombinant viruses expressing type 2 polymerase (Pol within a type 1 genome, were evaluated using the tk and non-HSV DNA mutagenesis assays to measure HSV replication-dependent errors and determine whether the higher mutation frequency of HSV-2 is a distinct property of type 2 polymerases. Results Although HSV-2 have mutation frequencies higher than HSV-1 in the tk assay, these errors are assay-specific. In fact, wild type HSV-1 and the antimutator HSV-1 PAAr5 exhibited a 2–4 fold higher frequency than HSV-2 in the non-HSV DNA mutatagenesis assay. Furthermore, regardless of assay, HSV-1 recombinants expressing HSV-2 Pol had error rates similar to HSV-1, whereas the high mutator virus, HSV-2 6757, consistently showed signficant errors. Additionally, plasmid DNA containing the HSV-2 tk gene, but not type 1 tk or LacZ DNA, was shown to form an anisomorphic DNA stucture. Conclusions This study suggests that the Pol is not solely responsible for the virus-type specific differences in mutation frequency. Accordingly, it is possible that (a mutations may be modulated by other viral polypeptides cooperating with Pol, and (b the localized secondary structure of the viral genome may partially account for the apparently enhanced error frequency of HSV-2.

Identification of a mutation in ADD1/SREBP-1 in the spontaneously hypertensive rat

Czech Academy of Sciences Publication Activity Database

Pravenec, Michal; Jansa, Petr; Kostka, Vlastimil; Zídek, Václav; Křen, Vladimír; Forejt, Jiří; Kurtz, T. W.

2001-01-01

Roč. 12, č. 4 (2001), s. 295-298 ISSN 0938-8990 R&D Projects: GA ČR(CZ) GA305/00/1646; GA MŠk(CZ) LN00A079; GA ČR(CZ) GV204/98/K015 Grant - others:HHMI(US) 55000331 Institutional research plan: CEZ:AV0Z5011922 Keywords : mutations in genes * ADD1/SREBP-1c * spontaneously hypertensive rat Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.318, year: 2001

A case report of spontaneous mutation (C33>U) in the iron-responsive element of L-ferritin causing hyperferritinemia-cataract syndrome.

LENUS (Irish Health Repository)

Cao, Wei

2010-01-15

The hereditary hyperferritinemia cataract syndrome (HHCS) is an autosomal dominant disorder characterized by juvenile-onset cataracts and elevated serum ferritin levels. It is caused by mutation in the iron response element (IRE) within the 5\\'UTR of L-ferritin gene. The mutation results in a loss of post-transcriptional negative feedback exerted by the interaction between iron regulatory proteins 1, 2 (IRP1 and IRP2) and IRE, which leads to uncontrolled expression of L-ferritin. In this paper, we describe the molecular pathogenesis of non-hereditary hyperferritinemia cataract syndrome (non-H-HCS) in a patient with typical HHCS ocular lens morphology and high ferritin levels without obvious family history. Initial sequencing of the full-length L-ferritin cloned from genomic DNA demonstrated a mutation (C33>T) in the IRE of the affected patient but not in her unaffected family members. The mutation (C\\/T heterozygote) was also detected in cDNA derived from her blood mononuclear cells. Structure-prediction-modeling indicates that this mutation would significantly alter the secondary structure of the IRE, resulting in a loss of the interaction between IRP and IRE. By using IRP1\\/IRP2-human IgG1 Fc fusion proteins, we established a novel in vitro report system (modified ELISA) to verify impaired IRE\\/IRP binding. Both the C33>U and A40G mutations (the first identified mutation for HHCS) showed a dramatically decreased binding to IRP1\\/IRP2 protein, compared to the normal IRE RNA. Surprisingly, a decrease in L-ferritin mRNA levels was observed in the affected patient compared to controls suggesting a mechanism of transcriptional negative feedback by high intracellular L-ferritin protein levels not described heretofore. Taken together, spontaneous mutation in the IRE of L-ferritin may cause non-H-HCS by the same mechanism as HHCS. In addition, under abnormal circumstances, the protein level of L-ferritin may be principally controlled by post

Spontaneous mutations in the flhD operon generate motility heterogeneity in Escherichia coli biofilm.

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Horne, Shelley M; Sayler, Joseph; Scarberry, Nicholas; Schroeder, Meredith; Lynnes, Ty; Prüß, Birgit M

2016-11-08

Heterogeneity and niche adaptation in bacterial biofilm involve changes to the genetic makeup of the bacteria and gene expression control. We hypothesized that i) spontaneous mutations in the flhD operon can either increase or decrease motility and that ii) the resulting motility heterogeneity in the biofilm might lead to a long-term increase in biofilm biomass. We allowed the highly motile E. coli K-12 strain MC1000 to form seven- and fourteen-day old biofilm, from which we recovered reduced motility isolates at a substantially greater frequency (5.4 %) than from a similar experiment with planktonic bacteria (0.1 %). Biofilms formed exclusively by MC1000 degraded after 2 weeks. In contrast, biofilms initiated with a 1:1 ratio of MC1000 and its isogenic flhD::kn mutant remained intact at 4 weeks and the two strains remained in equilibrium for at least two weeks. These data imply that an 'optimal' biofilm may contain a mixture of motile and non-motile bacteria. Twenty-eight of the non-motile MC1000 isolates contained an IS1 element in proximity to the translational start of FlhD or within the open reading frames for FlhD or FlhC. Two isolates had an IS2 and one isolate had an IS5 in the open reading frame for FlhD. An additional three isolates contained deletions that included the RNA polymerase binding site, five isolates contained point mutations and small deletions in the open reading frame for FlhC. The locations of all these mutations are consistent with the lack of motility and further downstream within the flhD operon than previously published IS elements that increased motility. We believe that the location of the mutation within the flhD operon determines whether the effect on motility is positive or negative. To test the second part of our hypothesis where motility heterogeneity in a biofilm may lead to a long-term increase in biofilm biomass, we quantified biofilm biomass by MC1000, MC1000 flhD::kn, and mixtures of the two strains at ratios of 1:1, 10

Anaerobic growth of Bacillus subtilis alters the spectrum of spontaneous mutations in the rpoB gene leading to rifampicin resistance.

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Nicholson, Wayne L; Park, Roy

2015-12-01

Spontaneous rifampicin-resistant (RFM(R)) mutants were isolated from Bacillus subtilis 168 cultivated in the presence or absence of oxygen. By DNA sequencing, the mutations were located within Cluster I of the rpoB gene encoding the β subunit of RNA polymerase. The spectrum of RFM(R) rpoB mutations isolated from B. subtilis cells grown anaerobically differed from aerobically grown cells, not only with respect to the location of mutations within Cluster I but also in the class of mutation observed (transition versus transversion). In the absence of RFM, RFM(R) mutants exhibited poorer growth under anaerobic conditions than did the wild-type strain, indicating their lower fitness in the absence of antibiotic selection. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Spontaneous evolution of an unusual cortical malformation in SOX2 anophthalmia syndrome

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Jay Desai

2013-01-01

Full Text Available Brain malformations such as agenesis and dysgenesis of corpus callosum, pituitary hypoplasia, hypothalamic hamartoma, mesial temporal periventricular heterotopia, and abnormally oriented and misshapen hippocampi have been described with SOX2 gene mutations. A neocortical malformation is presented here in association with SOX2 deletion that over time underwent spontaneous evolution and decrease in size.

The ducky(2J) mutation in Cacna2d2 results in reduced spontaneous Purkinje cell activity and altered gene expression.

Science.gov (United States)

Donato, Roberta; Page, Karen M; Koch, Dietlind; Nieto-Rostro, Manuela; Foucault, Isabelle; Davies, Anthony; Wilkinson, Tonia; Rees, Michele; Edwards, Frances A; Dolphin, Annette C

2006-11-29

The mouse mutant ducky and its allele ducky(2J) represent a model for absence epilepsy characterized by spike-wave seizures and cerebellar ataxia. These mice have mutations in Cacna2d2, which encodes the alpha2delta-2 calcium channel subunit. Of relevance to the ataxic phenotype, alpha2delta-2 mRNA is strongly expressed in cerebellar Purkinje cells (PCs). The Cacna2d2(du2J) mutation results in a 2 bp deletion in the coding region and a complete loss of alpha2delta-2 protein. Here we show that du(2J)/du(2J) mice have a 30% reduction in somatic calcium current and a marked fall in the spontaneous PC firing rate at 22 degrees C, accompanied by a decrease in firing regularity, which is not affected by blocking synaptic input to PCs. At 34 degrees C, du(2J)/du(2J) PCs show no spontaneous intrinsic activity. Du(2J)/du(2J) mice also have alterations in the cerebellar expression of several genes related to PC function. At postnatal day 21, there is an elevation of tyrosine hydroxylase mRNA and a reduction in tenascin-C gene expression. Although du(2J)/+ mice have a marked reduction in alpha2delta-2 protein, they show no fall in PC somatic calcium currents or increase in cerebellar tyrosine hydroxylase gene expression. However, du(2J)/+ PCs do exhibit a significant reduction in firing rate, correlating with the reduction in alpha2delta-2. A hypothesis for future study is that effects on gene expression occur as a result of a reduction in somatic calcium currents, whereas effects on PC firing occur as a long-term result of loss of alpha2delta-2 and/or a reduction in calcium currents and calcium-dependent processes in regions other than the soma.

Molecular analysis of two mouse dilute locus deletion mutations: Spontaneous dilute lethal20J and radiation-induced dilute prenatal lethal Aa2 alleles

International Nuclear Information System (INIS)

Strobel, M.C.; Seperack, P.K.; Copeland, N.G.; Jenkins, N.A.

1990-01-01

The dilute (d) coat color locus of mouse chromosome 9 has been identified by more than 200 spontaneous and mutagen-induced recessive mutations. With the advent of molecular probes for this locus, the molecular lesion associated with different dilute alleles can be recognized and precisely defined. In this study, two dilute mutations, dilute-lethal20J (dl20J) and dilute prenatal lethal Aa2, have been examined. Using a dilute locus genomic probe in Southern blot analysis, we detected unique restriction fragments in dl20J and Aa2 DNA. Subsequent analysis of these fragments showed that they represented deletion breakpoint fusion fragments. DNA sequence analysis of each mutation-associated deletion breakpoint fusion fragment suggests that both genomic deletions were generated by nonhomologous recombination events. The spontaneous dl20J mutation is caused by an interstitial deletion that removes a single coding exon of the dilute gene. The correlation between this discrete deletion and the expression of all dilute-associated phenotypes in dl20J homozygotes defines the dl20J mutation as a functional null allele of the dilute gene. The radiation-induced Aa2 allele is a multilocus deletion that, by complementation analysis, affects both the dilute locus and the proximal prenatal lethal-3 (pl-3) functional unit. Molecular analysis of the Aa2 deletion breakpoint fusion fragment has provided access to a previously undefined gene proximal to d. Initial characterization of this new gene suggests that it may represent the genetically defined pl-3 functional unit

Mutational pattern of the nurse shark antigen receptor gene (NAR) is similar to that of mammalian Ig genes and to spontaneous mutations in evolution: the translesion synthesis model of somatic hypermutation.

Science.gov (United States)

Diaz, M; Velez, J; Singh, M; Cerny, J; Flajnik, M F

1999-05-01

The pattern of somatic mutations of shark and frog Ig is distinct from somatic hypermutation of Ig in mammals in that there is a bias to mutate GC base pairs and a low frequency of mutations. Previous analysis of the new antigen receptor gene in nurse sharks (NAR), however, revealed no bias to mutate GC base pairs and the frequency of mutation was comparable to that of mammalian IgG. Here, we analyzed 1023 mutations in NAR and found no targeting of the mechanism to any particular nucleotide but did obtain strong evidence for a transition bias and for strand polarity. As seen for all species studied to date, the serine codon AGC/T in NAR was a mutational hotspot. The NAR mutational pattern is most similar to that of mammalian IgG and furthermore both are strikingly akin to mutations acquired during the neutral evolution of nuclear pseudogenes, suggesting that a similar mechanism is at work for both processes. In yeast, most spontaneous mutations are introduced by the translesion synthesis DNA polymerase zeta (REV3) and in various DNA repair-deficient backgrounds transitions were more often REV3-dependent than were transversions. Therefore, we propose a model of somatic hypermutation where DNA polymerase zeta is recruited to the Ig locus. An excess of DNA glycosylases in germinal center reactions may further enhance the mutation frequency by a REV3-dependent mutagenic process known as imbalanced base excision repair.

Decrease in specific micronutrient intake in colorectal cancer patients with tumors presenting Ki-ras mutation

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JORDI SALAS; NURIA LASO; SERGI MAS; M. JOSE LAFUENTE; XAVIER CASTERAD; MANUEL TRIAS; ANTONIO BALLESTA; RAFAEL MOLINA; CARLOS ASCASO; SHICHUN ZHENG; JOHN K. WIENCKE; AMALIA LAFUENTE

2004-01-01

Decrease in specific micronutrient intake in colorectal cancer patients with tumors presenting Ki-ras mutation BACKGROUND: The diversity of the Mediterranean diet and the heterogeneity of acquired genetic alterations in colorectal cancer (CRC) led us to examine the possible association between dietary factors and mutations, such as Ki-ras mutations, in genes implicated in the pathogenesis of these neoplasms. PATIENTS AND METHODS: The study was based on 246 cases and 296 controls. For th...

A case of primary familial congenital polycythemia with a novel EPOR mutation: possible spontaneous remission/alleviation by menstrual bleeding.

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Toriumi, Naohisa; Kaneda, Makoto; Hatakeyama, Naoki; Manabe, Hiromi; Okajima, Kazuki; Sakurai, Yukari; Yamamoto, Masayo; Sarashina, Takeo; Ikuta, Katsuya; Azuma, Hiroshi

2018-04-05

A 10-year-old girl with persistent erythrocytosis and ruddy complexion was diagnosed with primary familial congenital polycythemia (PFCP) involving a novel heterozygous mutation of c.1220C>A, p.Ser407X in exon 8 of the erythropoietin receptor gene (EPOR). This mutation causes truncation of EPOR, resulting in loss of the cytoplasmic region, which is necessary for negative regulation of erythropoietin signal transmission. Genetic analysis showed that the mutated EPOR was inherited from her mother. Her mother had polycythemia and had undergone venesection several times when she was young, but her polycythemic state appeared to have resolved. Venesection was not needed to maintain Hct levels within normal range. For the case reported here, venesection was also conducted to maintain the blood Hct level below 50%. We observed that after the patient experienced menarche, the volume and frequency of venesection needed to maintain Hct level < 50% were clearly reduced compared with those before menarche. These findings suggest that, in female patients with this type of EPOR mutation, menstruation might reduce blood volume in a manner similar to venesection. Spontaneous remission of erythrocytosis may thus occur after the start of menstrual bleeding.

Fitness decline under osmotic stress in Caenorhabditis elegans populations subjected to spontaneous mutation accumulation at varying population sizes.

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Katju, Vaishali; Packard, Lucille B; Keightley, Peter D

2018-04-01

The consequences of mutations for population fitness depends on their individual selection coefficients and the effective population size. An earlier study of Caenorhabditis elegans spontaneous mutation accumulation lines evolved for 409 generations at three population sizes found that N e   = 1 populations declined significantly in fitness whereas the fitness of larger populations (N e   = 5, 50) was indistinguishable from the ancestral control under benign conditions. To test if larger MA populations harbor a load of cryptic deleterious mutations that are obscured under benign laboratory conditions, we measured fitness under osmotic stress via exposure to hypersaline conditions. The fitness of N e   = 1 lines exhibited a further decline under osmotic stress compared to benign conditions. However, the fitness of larger populations remained indistinguishable from that of the ancestral control. The average effects of deleterious mutations in N e   = 1 lines were estimated to be 22% for productivity and 14% for survivorship, exceeding values previously detected under benign conditions. Our results suggest that fitness decline is due to large effect mutations that are rapidly removed via selection even in small populations, with implications for conservation practices. Genetic stochasticity may not be as potent and immediate a threat to the persistence of small populations as other demographic and environmental stochastic factors. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Fullerenol C{sub 60}(OH){sub 24} nanoparticles decrease relaxing effects of dimethyl sulfoxide on rat uterus spontaneous contraction

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Slavic, Marija, E-mail: marija17@ibiss.bg.ac.rs [University of Belgrade, Department for Physiology, Institute for Biological Research ' Sinisa Stankovic' (IBISS) (Serbia); Djordjevic, Aleksandar [University of Novi Sad, Department of Chemistry, Biochemistry and the Environment, Faculty of Sciences (Serbia); Radojicic, Ratko [University of Belgrade, Faculty of Biology (Serbia); Milovanovic, Slobodan [University of East Sarajevo, Department of Pharmacology, Faculty of Medicine at Foca (Bosnia and Herzegowina); Orescanin-Dusic, Zorana [University of Belgrade, Department for Physiology, Institute for Biological Research ' Sinisa Stankovic' (IBISS) (Serbia); Rakocevic, Zlatko [University of Belgrade, Institute for Nuclear Sciences ' Vinca' (Serbia); Spasic, Mihajlo B.; Blagojevic, Dusko [University of Belgrade, Department for Physiology, Institute for Biological Research ' Sinisa Stankovic' (IBISS) (Serbia)

2013-05-15

Dimethyl sulfoxide (DMSO) is a widely used solvent and cryoprotectant that can cause impaired blood flow, reduction in intracranial pressure, tissue edema, inflammatory reactions, inhibition of vascular smooth muscle cell migration and proliferation, processes which can lead to atherosclerosis of the coronary, peripheral and cerebral circulation. Although the adverse effects are rare when DMSO is administered in clinically established concentrations, there is no safe antagonist for an overdose. In this work, we treated isolated spontaneous and calcium-induced contractile active rat uteri (Wistar, virgo intacta), with DMSO and fullerenol C{sub 60}(OH){sub 24} nanoparticle (FNP) in DMSO. FNP is a water-soluble derivative of fullerene C{sub 60}. Its size is a 1.1 nm in diameter and is a very promising candidate for a drug carrier in nanomedicine. FNP also displays free radical scavenging activity. DMSO decreased both spontaneous and calcium-induced contractions. In contrast, FNP only decreased spontaneous contraction. FNP decreased copper-zinc superoxide dismutase activity and prevented the DMSO-induced increase in glutathione reductase activity. Atomic force microscopy detected that FNP aggregated with calcium ions. Our results indicate that FNP has properties that make it a good candidate to be a modulator of DMSO activity which could minimize side effects of the latter.

The ducky2J mutation in Cacna2d2 results in reduced spontaneous Purkinje cell activity and altered gene expression

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Donato, Roberta; Page, Karen M.; Koch, Dietlind; Nieto-Rostro, Manuela; Foucault, Isabelle; Davies, Anthony; Wilkinson, Tonia; Rees, Michele; Edwards, Frances A.; Dolphin, Annette C.

2006-01-01

The mouse mutant ducky and its allele ducky2J represent a model for absence epilepsy characterized by spike-wave seizures, and cerebellar ataxia. These mice have mutations in Cacna2d2, which encodes the α2δ-2 calcium channel subunit. Of relevance to the ataxic phenotype, α2δ-2 mRNA is strongly expressed in cerebellar Purkinje cells (PCs). The Cacna2d2du2J mutation results in a two base-pair deletion in the coding region and a complete loss of α2δ-2 protein. Here we show that du2J/du2J mice have a 30% reduction in somatic calcium current, and a marked fall in the spontaneous PC firing rate at 22°C, accompanied by a decrease in firing regularity, which is not affected by blocking synaptic input to PCs. At 34°C du2J/du2J PCs show no spontaneous intrinsic activity. Du2J/du2J mice also have alterations in the cerebellar expression of several genes related to PC function. At P21 there is an elevation of tyrosine hydroxylase mRNA and a reduction in tenascin-C gene expression. Although du2J/+ mice have a marked reduction in α2δ-2 protein, they show no fall in PC somatic calcium currents or increase in cerebellar tryrosine hydroxylase gene expression. However, du2J/+ PCs do exhibit a significant reduction in firing rate, correlating with the reduction in α2δ-2. A hypothesis for future study is that effects on gene expression occur as a result of a reduction in somatic calcium currents, whereas effects on PC firing occur as a long-term result of loss of α2δ-2 and/or a reduction in calcium currents and calcium-dependent processes in regions other than the soma. PMID:17135419

Aerobic Swim Training Restores Aortic Endothelial Function by Decreasing Superoxide Levels in Spontaneously Hypertensive Rats

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Camila P. Jordão

Full Text Available OBJECTIVE: We aimed to determine whether aerobic training decreases superoxide levels, increases nitric oxide levels, and improves endothelium-dependent vasodilation in the aortas of spontaneously hypertensive rats. METHODS: Spontaneously hypertensive rats (SHR and Wistar Kyoto rats (WKY were distributed into 2 groups: sedentary (SHRsd and WKYsd, n=10 each and swimming-trained (SHRtr, n=10 and WKYtr, n=10, respectively. The trained group participated in training sessions 5 days/week for 1 h/day with an additional work load of 4% of the animal’s body weight. After a 10-week sedentary or aerobic training period, the rats were euthanized. The thoracic aortas were removed to evaluate the vasodilator response to acetylcholine (10-10 to 10-4 M with or without preincubation with L-NG-nitro-L-arginine methyl ester hydrochloride (L-NAME; 10-4 M in vitro. The aortic tissue was also used to assess the levels of the endothelial nitric oxide synthase and nicotinamide adenine dinucleotide oxidase subunit isoforms 1 and 4 proteins, as well as the superoxide and nitrite contents. Blood pressure was measured using a computerized tail-cuff system. RESULTS: Aerobic training significantly increased the acetylcholine-induced maximum vasodilation observed in the SHRtr group compared with the SHRsd group (85.9±4.3 vs. 71.6±5.2%. Additionally, in the SHRtr group, superoxide levels were significantly decreased, nitric oxide bioavailability was improved, and the levels of the nicotinamide adenine dinucleotide oxidase subunit isoform 4 protein were decreased compared to the SHRsd group. Moreover, after training, the blood pressure of the SHRtr group decreased compared to the SHRsd group. Exercise training had no effect on the blood pressure of the WKYtr group. CONCLUSIONS: In SHR, aerobic swim training decreased vascular superoxide generation by nicotinamide adenine dinucleotide oxidase subunit isoform 4 and increased nitric oxide bioavailability, thereby improving

[Control levels of Sin3 histone deacetylase for spontaneous and UV-induced mutagenesis in yeasts Saccharomyces cerevisiae].

Science.gov (United States)

Lebovka, I Iu; Kozhina, T N; Fedorova, I V; Peshekhonov, V T; Evstiukhina, T A; Chernenkov, A Iu; Korolev, V G

2014-01-01

SIN3 gene product operates as a repressor for a huge amount of genes in Saccharomyces cerevisiae. Sin3 protein with a mass of about 175 kDa is a member of the RPD3 protein complex with an assessed mass of greater than 2 million Da. It was previously shownthat RPD3 gene mutations influence recombination and repair processes in S. cerevisiae yeasts. We studied the impacts of the sin3 mutation on UV-light sensitivity and UV-induced mutagenesis in budding yeast cells. The deletion ofthe SIN3 gene causes weak UV-sensitivity of mutant budding cells as compared to the wild-type strain. These results show that the sin3 mutation decreases both spontaneous and UV-induced levels of levels. This fact is hypothetically related to themalfunction of ribonucleotide reductase activity regulation, which leads to a decrease in the dNTP pool and the inaccurate error-prone damage bypass postreplication repair pathway, which in turn provokes a reduction in the incidence of mutations.

Effects of a tumor promoter and an anti-promoter on spontaneous and UV-induced 6-thioguanine-resistant mutations and sister-chromatid exchanges in V79 Chinese hamster cells

International Nuclear Information System (INIS)

Fujiwara, Y.; Kano, Y.; Tatsumi, M.; Paul, P.

1980-01-01

The effects of a tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) and/or an anti-promoter antipain (protease inhibitor) on spontaneous and ultraviolet-induced sister-chromatid exchanges (SCEs) and 6-thioguanine-resistant (6TGsup(r)) recessive mutations were examined in V79 Chinese hamster cells in culture. TPA and/or antipain neither significantly altered base-line and UV-induced immediate SCE frequencies, nor decreased the level of delayed SCEs which persisted 6-7 days after irradiation. TPA and/or antipain appeared to enhance the recovery of UV-induced 6TGsup(r) colonies at the plateau expression phase despite non-mutagenicity by themselves and unaltered metabolic cooperation. Thus, the results conceivably imply that the 6TGsup(r)-recessive mutation expression, but not fixation, can be modulated at the cell level by TPA and/or antipain. Our results, together with the recent results of Loveday and Latt, may argue against the notion that TPA enhances the antipain-suppressible SCEs as an index of mitotic recombination in relevance with a tumor-promotion mechanism. (orig.)

Longitudinal Lung Function Decrease in Subjects with Spontaneous Healed Pulmonary Tuberculosis.

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Lee, Seung Heon; Kwon, Amy M; Yang, Hae-Chung; Lee, Seung Ku; Kim, Young; Choi, Jong Hyun; Kim, Je Hyeong; Shin, Chol

2016-01-01

We compared the longitudinal course of post-bronchodilator Forced Expiratory Volume in 1 second (pFEV1) over a 10-year period in subjects with spontaneous healed pulmonary tuberculosis (SHPTB) with that in normal subjects. We prospectively investigated 339 subjects with SHPTB and 3211 normal subjects. pFEV1 values measured biannually over 10 years were analyzed using mixed effects model. At baseline, there were no differences in gender, smoking amount, and mean height, except mean age (50.0 ± 8.1 VS. 48.1 ± 7.3, P< 0.001) between the SHPTB and normal group. 52% of the 339 participants with SHPTB and 56% of the 3211 normal participants participated till the end of study. According to the final model, the SHPTB group showed significantly larger decrease in the average pFEV1 over the time than the normal group (P< 0.001) adjusted for gender, age, height, smoking pack years, and time effects. Especially, the interaction effect between time and group was statistically significant (P = 0.036). The average lung function in terms of pFEV1 decreases faster in subjects with SHPTB than in normal individuals over time.

X-ray-induced bystander response reduce spontaneous mutations in V79 cells

International Nuclear Information System (INIS)

Maeda, Munetoshi; Kobayashi, Katsumi; Matsumoto, Hideki; Usami, Noriko; Tomiya, Masanori

2013-01-01

The potential for carcinogenic risks is increased by radiation-induced bystander responses; these responses are the biological effects in unirradiated cells that receive signals from the neighboring irradiated cells. Bystander responses have attracted attention in modern radiobiology because they are characterized by non-linear responses to low-dose radiation. We used a synchrotron X-ray microbeam irradiation system developed at the Photon Factory, High Energy Accelerator Research Organization, KEK, and showed that nitric oxide (NO)-mediated bystander cell death increased biphasically in a dose-dependent manner. Here, we irradiated five cell nuclei using 10 × 10 µm 2 5.35 keV X-ray beams and then measured the mutation frequency at the hypoxanthine-guanosine phosphoribosyl transferase (HPRT) locus in bystander cells. The mutation frequency with the null radiation dose was 2.6 × 10 -5 (background level), and the frequency decreased to 5.3 × 10 -6 with a dose of approximately 1 Gy (absorbed dose in the nucleus of irradiated cells). At high doses, the mutation frequency returned to the background level. A similar biphasic dose-response effect was observed for bystander cell death. Furthermore, we found that incubation with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (carboxy-PTIO), a specific scavenger of NO, suppressed not only the biphasic increase in bystander cell death but also the biphasic reduction in mutation frequency of bystander cells. These results indicate that the increase in bystander cell death involves mechanisms that suppress mutagenesis. This study has thus shown that radiation-induced bystander responses could affect processes that protect the cell against naturally occurring alterations such as mutations. (author)

Mutator activity in Schizophyllum commune

Energy Technology Data Exchange (ETDEWEB)

Shneyour, Y.; Koltin, Y. (Tel Aviv Univ. (Israel). Dept. of Microbiology)

1983-01-01

A strain with an elevated level of spontaneous mutations and an especially high rate of reversion at a specific locus (pab/sup -/) was identified. The mutator trait is recessive. UV sensitivity and the absence of a UV-specific endonucleolytic activity were associated with the enhancement of the mutation rate in mutator strains. The endonuclease associated with the regulation of the mutation rate also acted on single-stranded DNA. The molecular weight of this enzyme is about 38,000 daltons.

Identification of a nonsense mutation in CWC15 associated with decreased reproductive efficiency in Jersey cattle.

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Tad S Sonstegard

Full Text Available With the recent advent of genomic tools for cattle, several recessive conditions affecting fertility have been identified and selected against, such as deficiency of uridine monophosphate synthase, complex vertebral malformation, and brachyspina. The current report refines the location of a recessive haplotype affecting fertility in Jersey cattle using crossover haplotypes, discovers the causative mutation using whole genome sequencing, and examines the gene's role in embryo loss. In an attempt to identify unknown recessive lethal alleles in the current dairy population, a search using deep Mendelian sampling of 5,288 Jersey cattle was conducted for high-frequency haplotypes that have a deficit of homozygotes at the population level. This search led to the discovery of a putative recessive lethal in Jersey cattle on Bos taurus autosome 15. The haplotype, denoted JH1, was associated with reduced fertility, and further investigation identified one highly-influential Jersey bull as the putative source ancestor. By combining SNP analysis of whole-genome sequences aligned to the JH1 interval and subsequent SNP validation a nonsense mutation in CWC15 was identified as the likely causative mutation underlying the fertility phenotype. No homozygous recessive individuals were found in 749 genotyped animals, whereas all known carriers and carrier haplotypes possessed one copy of the mutant allele. This newly identified lethal has been responsible for a substantial number of spontaneous abortions in Jersey dairy cattle throughout the past half-century. With the mutation identified, selection against the deleterious allele in breeding schemes will aid in reducing the incidence of this defect in the population. These results also show that carrier status can be imputed with high accuracy. Whole-genome resequencing proved to be a powerful strategy to rapidly identify a previously mapped deleterious mutation in a known carrier of a recessive lethal allele.

The molecular anatomy of spontaneous germline mutations in human testes.

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Jian Qin

2007-09-01

Full Text Available The frequency of the most common sporadic Apert syndrome mutation (C755G in the human fibroblast growth factor receptor 2 gene (FGFR2 is 100-1,000 times higher than expected from average nucleotide substitution rates based on evolutionary studies and the incidence of human genetic diseases. To determine if this increased frequency was due to the nucleotide site having the properties of a mutation hot spot, or some other explanation, we developed a new experimental approach. We examined the spatial distribution of the frequency of the C755G mutation in the germline by dividing four testes from two normal individuals each into several hundred pieces, and, using a highly sensitive PCR assay, we measured the mutation frequency of each piece. We discovered that each testis was characterized by rare foci with mutation frequencies 10(3 to >10(4 times higher than the rest of the testis regions. Using a model based on what is known about human germline development forced us to reject (p < 10(-6 the idea that the C755G mutation arises more frequently because this nucleotide simply has a higher than average mutation rate (hot spot model. This is true regardless of whether mutation is dependent or independent of cell division. An alternate model was examined where positive selection acts on adult self-renewing Ap spermatogonial cells (SrAp carrying this mutation such that, instead of only replacing themselves, they occasionally produce two SrAp cells. This model could not be rejected given our observed data. Unlike the disease site, similar analysis of C-to-G mutations at a control nucleotide site in one testis pair failed to find any foci with high mutation frequencies. The rejection of the hot spot model and lack of rejection of a selection model for the C755G mutation, along with other data, provides strong support for the proposal that positive selection in the testis can act to increase the frequency of premeiotic germ cells carrying a mutation

Folliculin mutations are not associated with severe COPD

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Litonjua Augusto A

2008-12-01

Full Text Available Abstract Background Rare loss-of-function folliculin (FLCN mutations are the genetic cause of Birt-Hogg-Dubé syndrome, a monogenic disorder characterized by spontaneous pneumothorax, fibrofolliculomas, and kidney tumors. Loss-of-function folliculin mutations have also been described in pedigrees with familial spontaneous pneumothorax. Because the majority of patients with folliculin mutations have radiographic evidence of pulmonary cysts, folliculin has been hypothesized to contribute to the development of emphysema. To determine whether folliculin sequence variants are risk factors for severe COPD, we genotyped seven previously reported Birt-Hogg-Dubé or familial spontaneous pneumothorax associated folliculin mutations in 152 severe COPD probands participating in the Boston Early-Onset COPD Study. We performed bidirectional resequencing of all 14 folliculin exons in a subset of 41 probands and subsequently genotyped four identified variants in an independent sample of345 COPD subjects from the National Emphysema Treatment Trial (cases and 420 male smokers with normal lung function from the Normative Aging Study (controls. Results None of the seven previously reported Birt-Hogg-Dubé or familial spontaneous pneumothorax mutations were observed in the 152 severe, early-onset COPD probands. Exon resequencing identified 31 variants, including two non-synonymous polymorphisms and two common non-coding polymorphisms. No significant association was observed for any of these four variants with presence of COPD or emphysema-related phenotypes. Conclusion Genetic variation in folliculin does not appear to be a major risk factor for severe COPD. These data suggest that familial spontaneous pneumothorax and COPD have distinct genetic causes, despite some overlap in radiographic characteristics.

Is Increased Low-dose somatic Radiosensitivity Associated with Increased Transgenerational Germline Mutation

International Nuclear Information System (INIS)

Brenner, David J.

2008-01-01

Using single-molecule polymerase chain reaction, the frequency of spontaneous and radiation-induced mutation at an expanded simple tandem repeat (ESTR) locus was studied in DNA samples extracted from sperm and bone marrow of Atm knockout (Atm+/-) heterozygous male mice. The frequency of spontaneous mutation in sperm and bone marrow in Atm+/- males did not significantly differ from that in wild-type BALB/c mice. Acute gamma-ray exposure did not affect ESTR mutation frequency in bone marrow and resulted in similar increases in sperm samples taken from Atm+/- and BALB/c males. Taken together, these results suggest that the Atm haploinsufficiency analyzed in our study does not affect spontaneous and radiation-induced ESTR mutation frequency in mice

DNA sequence analysis of X-ray induced Adh null mutations in Drosophila melanogaster

International Nuclear Information System (INIS)

Mahmoud, J.; Fossett, N.G.; Arbour-Reily, P.; McDaniel, M.; Tucker, A.; Chang, S.H.; Lee, W.R.

1991-01-01

The mutational spectrum for 28 X-ray induced mutations and 2 spontaneous mutations, previously determined by genetic and cytogenetic methods, consisted of 20 multilocus deficiencies (19 induced and 1 spontaneous) and 10 intragenic mutations (9 induced and 1 spontaneous). One of the X-ray induced intragenic mutations was lost, and another was determined to be a recombinant with the allele used in the recovery scheme. The DNA sequence of two X-ray induced intragenic mutations has been published. This paper reports the results of DNA sequence analysis of the remaining intragenic mutations and a summary of the X-ray induced mutational spectrum. The combination of DNA sequence analysis with genetic complementation analysis shows a continuous distribution in size of deletions rather than two different types of mutations consisting of deletions and 'point mutations'. Sequencing is shown to be essential for detecting intragenic deletions. Of particular importance for future studies is the observation that all of the intragenic deletions consist of a direct repeat adjacent to the breakpoint with one of the repeats deleted

Single genome retrieval of context-dependent variability in mutation rates for human germline.

Science.gov (United States)

Sahakyan, Aleksandr B; Balasubramanian, Shankar

2017-01-13

Accurate knowledge of the core components of substitution rates is of vital importance to understand genome evolution and dynamics. By performing a single-genome and direct analysis of 39,894 retrotransposon remnants, we reveal sequence context-dependent germline nucleotide substitution rates for the human genome. The rates are characterised through rate constants in a time-domain, and are made available through a dedicated program (Trek) and a stand-alone database. Due to the nature of the method design and the imposed stringency criteria, we expect our rate constants to be good estimates for the rates of spontaneous mutations. Benefiting from such data, we study the short-range nucleotide (up to 7-mer) organisation and the germline basal substitution propensity (BSP) profile of the human genome; characterise novel, CpG-independent, substitution prone and resistant motifs; confirm a decreased tendency of moieties with low BSP to undergo somatic mutations in a number of cancer types; and, produce a Trek-based estimate of the overall mutation rate in human. The extended set of rate constants we report may enrich our resources and help advance our understanding of genome dynamics and evolution, with possible implications for the role of spontaneous mutations in the emergence of pathological genotypes and neutral evolution of proteomes.

Random mtDNA mutations modulate proliferation capacity in mouse embryonic fibroblasts

International Nuclear Information System (INIS)

Kukat, Alexandra; Edgar, Daniel; Bratic, Ivana; Maiti, Priyanka; Trifunovic, Aleksandra

2011-01-01

Highlights: → Increased mtDNA mutations in MEFs lead to high level of spontaneous immortalization. → This process is independent of endogenous ROS production. → Aerobic glycolysis significantly contributes to spontaneous immortalization of MEFs. -- Abstract: An increase in mtDNA mutation load leads to a loss of critical cells in different tissues thereby contributing to the physiological process of organismal ageing. Additionally, the accumulation of senescent cells that display changes in metabolic function might act in an active way to further disrupt the normal tissue function. We believe that this could be the important link missing in our understanding of the molecular mechanisms of premature ageing in the mtDNA mutator mice. We tested proliferation capacity of mtDNA mutator cells in vitro. When cultured in physiological levels of oxygen (3%) their proliferation capacity is somewhat lower than wild-type cells. Surprisingly, in conditions of increased oxidative stress (20% O 2 ) mtDNA mutator mouse embryonic fibroblasts exhibit continuous proliferation due to spontaneous immortalization, whereas the same conditions promote senescence in wild-type cells. We believe that an increase in aerobic glycolysis observed in mtDNA mutator mice is a major mechanism behind this process. We propose that glycolysis promotes proliferation and allows a fast turnover of metabolites, but also leads to energy crisis due to lower ATP production rate. This could lead to compromised replication and/or repair and therefore, in rare cases, might lead to mutations in tumor suppressor genes and spontaneous immortalization.

Mutated Genes in Schizophrenia Map to Brain Networks

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... Matters NIH Research Matters August 12, 2013 Mutated Genes in Schizophrenia Map to Brain Networks Schizophrenia networks ... have a high number of spontaneous mutations in genes that form a network in the front region ...

Molecular mechanisms of induced-mutations

International Nuclear Information System (INIS)

Kato, Takeshi

1985-01-01

The outcome of recent studies on mechanisms of induced-mutations is outlined with particular emphasis on the dependence of recA gene function in Escherichia coli. Genes involved in spontaneous mutation and x-ray- and chemical-induced mutation and genes involved in adaptive response are presented. As for SOS mutagenesis, SOS-induced regulation mechanisms and mutagenic routes are described. Furthermore, specificity of mutagens themselves are discussed in relation to mechanisms of base substitution, frameshift, and deletion mutagenesis. (Namekawa, K.)

EFFECTS OF THE ANTIMUTAGENS VANILLIN AND CINNAMALDEHYDE ON SPONTANEOUS MUTATION IN E. COLI LACL STRAINS AND ON GLOBAL GENE EXPRESSION IN SALMONELLA TA104 AND HUMAN HEPG2 CELLS

Science.gov (United States)

Effects of the Antimutagens Vanillin and Cinnamaldehyde on Spontaneous Mutation in E. coli lacI Strains and on Global Gene Epression in Salmonella TAlO4 and Human HepG2 Cells In previous work we have shown that vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutag...

The role of radiation induced mutations in crop Improvement

International Nuclear Information System (INIS)

Souframanien, J.

2017-01-01

Sudden, heritable changes in the genetic material, DNA, are known as mutations. Selection of naturally occurring mutations in wild, ancestral species helped humans in the domestication and further improvement of today's crop plants. Gregor Mendel in 1865 used several such natural mutants in his experiments with garden pea to formulate the laws of inheritance. The term mutation itself was used for the first time by Hugo de Vries in 1901 in his mutation theory. Plant breeding based on the science of genetics, as practiced over the past 100 years, exploited the available genetic variability in the primary gene pool of crop plants, and sometimes in related species. Primarily, simple selection of desirable offspring and cross breeding were the earlier methods of breeding and this utilized the occurrence of spontaneous mutations. In nature, occurrence of natural variability in the form of spontaneous mutations is extremely low (about 10 -6 ), which can be enhanced several fold (∼10 -3 ) by using ionizing radiations or chemical mutagens

Precise estimates of mutation rate and spectrum in yeast

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Zhu, Yuan O.; Siegal, Mark L.; Hall, David W.; Petrov, Dmitri A.

2014-01-01

Mutation is the ultimate source of genetic variation. The most direct and unbiased method of studying spontaneous mutations is via mutation accumulation (MA) lines. Until recently, MA experiments were limited by the cost of sequencing and thus provided us with small numbers of mutational events and therefore imprecise estimates of rates and patterns of mutation. We used whole-genome sequencing to identify nearly 1,000 spontaneous mutation events accumulated over ∼311,000 generations in 145 diploid MA lines of the budding yeast Saccharomyces cerevisiae. MA experiments are usually assumed to have negligible levels of selection, but even mild selection will remove strongly deleterious events. We take advantage of such patterns of selection and show that mutation classes such as indels and aneuploidies (especially monosomies) are proportionately much more likely to contribute mutations of large effect. We also provide conservative estimates of indel, aneuploidy, environment-dependent dominant lethal, and recessive lethal mutation rates. To our knowledge, for the first time in yeast MA data, we identified a sufficiently large number of single-nucleotide mutations to measure context-dependent mutation rates and were able to (i) confirm strong AT bias of mutation in yeast driven by high rate of mutations from C/G to T/A and (ii) detect a higher rate of mutation at C/G nucleotides in two specific contexts consistent with cytosine methylation in S. cerevisiae. PMID:24847077

Spontaneous and mutagen-induced deletions: mechanistic studies in Salmonella tester strain TA102

International Nuclear Information System (INIS)

Levin, D.E.; Marnett, L.J.; Ames, B.N.

1984-01-01

Salmonella tester strain TA102 carries the hisG428 ochre mutation on the multicopy plasmid pAQ1. DNA sequence analysis of 45 spontaneous revertants of hisG428 on the chromosome in the presence of pKM101 (strain TA103) indicates that hisG428 revertants fall into three major categories: (i) small, in-frame deletions (3 or 6 base pairs) that remove part or all of the ochre triplet; (ii) base substitution mutations at the ochre site; (iii) extragenic ochre suppressors. Deletion revertants are identified in a simple phenotypic screen by their resistance to the inhibitory histidine analog thiazolealanine, which feedback inhibits the wild-type hisG enzyme but not the enzyme resulting from the deletions. The effect of various genetic backgrounds on the generation of spontaneous deletion revertants was examined. The presence of a uvrB mutation or a recA mutation suppressed the generation of spontaneous deletion revertants to approximately 1/2.5. When hisG428 was in multiple copies on pAQ1, the frequency of spontaneous deletion revertants increased by 40-fold, which is the approximate copy number of pAQ1. Mutagenic agents that induce single-strand breaks in DNA (e.g., x-rays, bleomycin, and nalidixic acid) induced deletion revertants in TA102. These agents induced deletion revertants only in hisG428 on pAQ1 and only in the presence of pKM101. Deletion revertants were not induced by frameshift mutagens (i.e., ICR-191 and 9aminoacridine). These results indicate that different pathways exist for the generation of spontaneous and mutagen-induced deletion revertants of hisG428. 41 references, 2 figures, 3 tables

Saccharomyces cerevisiae mutants with enhanced induced mutation and altered mitotic gene conversion.

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Ivanov, E L; Kovaltzova, S V; Korolev, V G

1989-08-01

We have developed a method to isolate yeast (Saccharomyces cerevisiae) mutants with enhanced induced mutagenesis based on nitrous acid-induced reversion of the ade2-42 allele. Six mutants have been isolated and designated him (high induced mutagenesis), and 4 of them were studied in more detail. The him mutants displayed enhanced reversion of the ade2-42 allele, either spontaneous or induced by nitrous acid, UV light, and the base analog 6-N-hydroxylaminopurine, but not by gamma-irradiation. It is worth noting that the him mutants turned out not to be sensitive to the lethal effects of the mutagens used. The enhancement in mutation induced by nitrous acid, UV light, and 6-N-hydroxylaminopurine has been confirmed in a forward-mutation assay (induction of mutations in the ADE1, ADE2 genes). The latter agent revealed the most apparent differences between the him mutants and the wild-type strain and was, therefore, chosen for the genetic analysis of mutants, him mutations analyzed behaved as a single Mendelian trait; complementation tests indicated 3 complementation groups (HIM1, HIM2, and HIM3), each containing 1 mutant allele. Uracil-DNA glycosylase activity was determined in crude cell extracts, and no significant differences between the wild-type and him strains were detected. Spontaneous mitotic gene conversion at the ADE2 locus is altered in him1 strains, either increased or decreased, depending on the particular heteroallelic combination. Genetic evidence strongly suggests him mutations to be involved in a process of mismatch correction of molecular heteroduplexes.

Myostatin propeptide mutation of the hypermuscular Compact mice decreases the formation of myostatin and improves insulin sensitivity.

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Kocsis, Tamas; Trencsenyi, Gyorgy; Szabo, Kitti; Baan, Julia Aliz; Muller, Geza; Mendler, Luca; Garai, Ildiko; Reinauer, Hans; Deak, Ferenc; Dux, Laszlo; Keller-Pinter, Aniko

2017-03-01

The TGFβ family member myostatin (growth/differentiation factor-8) is a negative regulator of skeletal muscle growth. The hypermuscular Compact mice carry the 12-bp Mstn(Cmpt-dl1Abc) deletion in the sequence encoding the propeptide region of the precursor promyostatin, and additional modifier genes of the Compact genetic background contribute to determine the full expression of the phenotype. In this study, by using mice strains carrying mutant or wild-type myostatin alleles with the Compact genetic background and nonmutant myostatin with the wild-type background, we studied separately the effect of the Mstn(Cmpt-dl1Abc) mutation or the Compact genetic background on morphology, metabolism, and signaling. We show that both the Compact myostatin mutation and Compact genetic background account for determination of skeletal muscle size. Despite the increased musculature of Compact s, the absolute size of heart and kidney is not influenced by myostatin mutation; however, the Compact genetic background increases them. Both Compact myostatin and genetic background exhibit systemic metabolic effects. The Compact mutation decreases adiposity and improves whole body glucose uptake, insulin sensitivity, and 18 FDG uptake of skeletal muscle and white adipose tissue, whereas the Compact genetic background has the opposite effect. Importantly, the mutation does not prevent the formation of mature myostatin; however, a decrease in myostatin level was observed, leading to altered activation of Smad2, Smad1/5/8, and Akt, and an increased level of p-AS160, a Rab-GTPase-activating protein responsible for GLUT4 translocation. Based on our analysis, the Compact genetic background strengthens the effect of myostatin mutation on muscle mass, but those can compensate for each other when systemic metabolic effects are compared. Copyright © 2017 the American Physiological Society.

Prostatic relaxation induced by agmatine is decreased in spontaneously hypertensive rats.

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Lee, Liang-Ming; Tsai, Tsung-Chin; Chung, Hsien-Hui; Tong, Yat-Ching; Cheng, Juei-Tang

2012-09-01

What's known on the subject? and What does the study add? Neurotransmitters are known to control prostate contractility. Agmatine is one of them and induces relaxation through imidazoline receptors. The paper shows that the action of agmatine is reduced in hypertensive rats, and that this change is related to the decrease of ATP-sensitive potassium channels in the prostate. The findings can increase our understanding of the possible underlying mechanism for the development of clinical benign prostatic hyperplasia. To compare agmatine-induced prostatic relaxation in hypertensive and control rats. To investigate the responsible mechanism(s) and the role of the ATP-sensitive potassium channel. Prostate strips were isolated from male spontaneously hypertensive (SH) rats and normal Wistar-Kyoto (WKY) rats for measurement of isometric tension. The strips were precontracted with 1 µmol/L phenylephrine or 50 mmol/L KCl. Dose-dependent relaxation of the prostatic strips was studied by cumulative administration of agmatine, 1 to 100 µmol/L, into the organ bath. Effects of specific antagonists on agmatine-induced relaxation were studied. Western blotting analysis was used to measure the gene expression of the ATP-sensitive potassium channel in the rat prostate. Prostatic relaxation induced by agmatine was markedly reduced in SH rats compared with WKY rats. The relaxation caused by agmatine was abolished by BU224, a selective imidazoline I(2)-receptor antagonist, but was not modified by efaroxan at a dose sufficient to block imidazoline I(1)-receptors. The relaxation induced by diazoxide at a concentration sufficient to activate ATP-sensitive potassium channels was markedly reduced in the SH rat prostate. Expressions of ATP-sensitive potassium channel sulphonylurea receptor and inwardly rectifying potassium channel (Kir) 6.2 subunits were both decreased in the prostate of SH rats. The decrease of agmatine-induced prostatic relaxation in SH rats is related to the change in

Gain-of-function R225W mutation in human AMPKgamma(3 causing increased glycogen and decreased triglyceride in skeletal muscle.

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Sheila R Costford

Full Text Available BACKGROUND: AMP-activated protein kinase (AMPK is a heterotrimeric enzyme that is evolutionarily conserved from yeast to mammals and functions to maintain cellular and whole body energy homeostasis. Studies in experimental animals demonstrate that activation of AMPK in skeletal muscle protects against insulin resistance, type 2 diabetes and obesity. The regulatory gamma(3 subunit of AMPK is expressed exclusively in skeletal muscle; however, its importance in controlling overall AMPK activity is unknown. While evidence is emerging that gamma subunit mutations interfere specifically with AMP activation, there remains some controversy regarding the impact of gamma subunit mutations. Here we report the first gain-of-function mutation in the muscle-specific regulatory gamma(3 subunit in humans. METHODS AND FINDINGS: We sequenced the exons and splice junctions of the AMPK gamma(3 gene (PRKAG3 in 761 obese and 759 lean individuals, identifying 87 sequence variants including a novel R225W mutation in subjects from two unrelated families. The gamma(3 R225W mutation is homologous in location to the gamma(2R302Q mutation in patients with Wolf-Parkinson-White syndrome and to the gamma(3R225Q mutation originally linked to an increase in muscle glycogen content in purebred Hampshire Rendement Napole (RN- pigs. We demonstrate in differentiated muscle satellite cells obtained from the vastus lateralis of R225W carriers that the mutation is associated with an approximate doubling of both basal and AMP-activated AMPK activities. Moreover, subjects bearing the R225W mutation exhibit a approximately 90% increase of skeletal muscle glycogen content and a approximately 30% decrease in intramuscular triglyceride (IMTG. CONCLUSIONS: We have identified for the first time a mutation in the skeletal muscle-specific regulatory gamma(3 subunit of AMPK in humans. The gamma(3R225W mutation has significant functional effects as demonstrated by increases in basal and AMP

Low Base-Substitution Mutation Rate in the Germline Genome of the Ciliate Tetrahymena thermophila

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2016-09-15

Tetrahymena thermophila, a model eukaryote. PLoS Biol. 4:e286. Farlow A, et al. 2015. The spontaneous mutation rate in the fission yeast Schizosaccharomyces...spontane- ous mutations in yeast . Proc Natl Acad Sci U S A. 105:9272–9277. Lynn DH, Doerder FP. 2012. The life and times of Tetrahymena. Methods Cell...Low Base-Substitution Mutation Rate in the Germline Genome of the Ciliate Tetrahymena thermophila Hongan Long1,2,y, David J. Winter3,*,y, Allan Y.-C

Rapid screening of spontaneous and radiation-induced structural changes at the vestigial gene of Drosophila melanogaster by polymerase chain reaction

International Nuclear Information System (INIS)

Aleksandrov, I.D.; Lapidus, I.L.; Aleksandrova, M.V.; Karpovskij, A.L.; Korablinova, S.V.; Levkovich, N.V.

1998-01-01

A total of 27 independent isolated spontaneous and gamma-ray-induced heritable mutations at the vestigial gene of Drosophila melanogaster were analysed by a rapid deletion screening method with polymerase chain reaction (PCR) amplification. According to the results obtained 36.4% (4 of 11) of spontaneous mutants and 62.5% (10 of 16) of gamma-ray-induced ones have revealed deficiency of one or more fragments studied. The rest of spontaneous and radiation mutants showed no alterations in the PCR patterns, indicating possible small scale changes (point mutations) inside the gene region studied or, probably, the gross lesions situated elsewhere. The distribution of the mutation damages in the gene region studied are discussed

Whole genome sequencing of mutation accumulation lines reveals a low mutation rate in the social amoeba Dictyostelium discoideum.

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Gerda Saxer

Full Text Available Spontaneous mutations play a central role in evolution. Despite their importance, mutation rates are some of the most elusive parameters to measure in evolutionary biology. The combination of mutation accumulation (MA experiments and whole-genome sequencing now makes it possible to estimate mutation rates by directly observing new mutations at the molecular level across the whole genome. We performed an MA experiment with the social amoeba Dictyostelium discoideum and sequenced the genomes of three randomly chosen lines using high-throughput sequencing to estimate the spontaneous mutation rate in this model organism. The mitochondrial mutation rate of 6.76×10(-9, with a Poisson confidence interval of 4.1×10(-9 - 9.5×10(-9, per nucleotide per generation is slightly lower than estimates for other taxa. The mutation rate estimate for the nuclear DNA of 2.9×10(-11, with a Poisson confidence interval ranging from 7.4×10(-13 to 1.6×10(-10, is the lowest reported for any eukaryote. These results are consistent with low microsatellite mutation rates previously observed in D. discoideum and low levels of genetic variation observed in wild D. discoideum populations. In addition, D. discoideum has been shown to be quite resistant to DNA damage, which suggests an efficient DNA-repair mechanism that could be an adaptation to life in soil and frequent exposure to intracellular and extracellular mutagenic compounds. The social aspect of the life cycle of D. discoideum and a large portion of the genome under relaxed selection during vegetative growth could also select for a low mutation rate. This hypothesis is supported by a significantly lower mutation rate per cell division in multicellular eukaryotes compared with unicellular eukaryotes.

PrP P102L and Nearby Lysine Mutations Promote Spontaneous In Vitro Formation of Transmissible Prions.

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Kraus, Allison; Raymond, Gregory J; Race, Brent; Campbell, Katrina J; Hughson, Andrew G; Anson, Kelsie J; Raymond, Lynne D; Caughey, Byron

2017-11-01

Accumulation of fibrillar protein aggregates is a hallmark of many diseases. While numerous proteins form fibrils by prion-like seeded polymerization in vitro , only some are transmissible and pathogenic in vivo To probe the structural features that confer transmissibility to prion protein (PrP) fibrils, we have analyzed synthetic PrP amyloids with or without the human prion disease-associated P102L mutation. The formation of infectious prions from PrP molecules in vitro has required cofactors and/or unphysiological denaturing conditions. Here, we demonstrate that, under physiologically compatible conditions without cofactors, the P102L mutation in recombinant hamster PrP promoted prion formation when seeded by minute amounts of scrapie prions in vitro Surprisingly, combination of the P102L mutation with charge-neutralizing substitutions of four nearby lysines promoted spontaneous prion formation. When inoculated into hamsters, both of these types of synthetic prions initiated substantial accumulation of prion seeding activity and protease-resistant PrP without transmissible spongiform encephalopathy (TSE) clinical signs or notable glial activation. Our evidence suggests that PrP's centrally located proline and lysine residues act as conformational switches in the in vitro formation of transmissible PrP amyloids. IMPORTANCE Many diseases involve the damaging accumulation of specific misfolded proteins in thread-like aggregates. These threads (fibrils) are capable of growing on the ends by seeding the refolding and incorporation of the normal form of the given protein. In many cases such aggregates can be infectious and propagate like prions when transmitted from one individual host to another. Some transmitted aggregates can cause fatal disease, as with human iatrogenic prion diseases, while other aggregates appear to be relatively innocuous. The factors that distinguish infectious and pathogenic protein aggregates from more innocuous ones are poorly understood

Variation in RNA virus mutation rates across host cells.

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Marine Combe

2014-01-01

Full Text Available It is well established that RNA viruses exhibit higher rates of spontaneous mutation than DNA viruses and microorganisms. However, their mutation rates vary amply, from 10(-6 to 10(-4 substitutions per nucleotide per round of copying (s/n/r and the causes of this variability remain poorly understood. In addition to differences in intrinsic fidelity or error correction capability, viral mutation rates may be dependent on host factors. Here, we assessed the effect of the cellular environment on the rate of spontaneous mutation of the vesicular stomatitis virus (VSV, which has a broad host range and cell tropism. Luria-Delbrück fluctuation tests and sequencing showed that VSV mutated similarly in baby hamster kidney, murine embryonic fibroblasts, colon cancer, and neuroblastoma cells (approx. 10(-5 s/n/r. Cell immortalization through p53 inactivation and oxygen levels (1-21% did not have a significant impact on viral replication fidelity. This shows that previously published mutation rates can be considered reliable despite being based on a narrow and artificial set of laboratory conditions. Interestingly, we also found that VSV mutated approximately four times more slowly in various insect cells compared with mammalian cells. This may contribute to explaining the relatively slow evolution of VSV and other arthropod-borne viruses in nature.

Mutation frequencies in male mice and the estimation of genetic hazards of radiation in men: (specific-locus mutations/dose-rate effect/doubling dose/risk estimation)

International Nuclear Information System (INIS)

Russell, W.L.; Kelly, E.M.

1982-01-01

Estimation of the genetic hazards of ionizing radiation in men is based largely on the frequency of transmitted specific-locus mutations induced in mouse spermatogonial stem cells at low radiation dose rates. The publication of new data on this subject has permitted a fresh review of all the information available. The data continue to show no discrepancy from the interpretation that, although mutation frequency decreases markedly as dose rate is decreased from 90 to 0.8 R/min (1 R = 2.6 X 10 -4 coulombs/kg) there seems to be no further change below 0.8 R/min over the range from that dose rate to 0.0007 R/min. Simple mathematical models are used to compute: (a) a maximum likelihood estimate of the induced mutation frequency at the low dose rates, and (b) a maximum likelihood estimate of the ratio of this to the mutation frequency at high dose rates in the range of 72 to 90 R/min. In the application of these results to the estimation of genetic hazards of radiation in man, the former value can be used to calculate a doubling dose - i.e., the dose of radiation that induces a mutation frequency equal to the spontaneous frequency. The doubling dose based on the low-dose-rate data compiled here is 110 R. The ratio of the mutation frequency at low dose rate to that at high dose rate is useful when it becomes necessary to extrapolate from experimental determinations, or from human data, at high dose rates to the expected risk at low dose rates. The ratio derived from the present analysis is 0.33

Identification and Characterization of Spontaneous Auxotrophic Mutants in Fusarium langsethiae

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Olga Gavrilova

2017-03-01

Full Text Available Analysis of 49 strains of Fusarium langsethiae originating from northern Europe (Russia, Finland, Sweden, UK, Norway, and Latvia revealed the presence of spontaneous auxotrophic mutants that reflect natural intraspecific diversity. Our investigations detected that 49.0% of F. langsethiae strains were auxotrophic mutants for biotin, and 8.2% of the strains required thiamine as a growth factor. They failed to grow on vitamin-free media. For both prototrophic and auxotrophic strains, no growth defect was observed in rich organic media. Without essential vitamins, a significant reduction in the growth of the auxotrophic strains results in a decrease of the formation of T-2 toxin and diacetoxyscirpenol. In addition, all analysed F. langsethiae strains were distinguished into two subgroups based on PCR product sizes. According to our results, 26 and 23 strains of F. langsethiae belong to subgroups I and II respectively. We determined that the deletion in the intergenic spacer (IGS region of the rDNA of F. langsethiae belonging to subgroup II is linked with temperature sensitivity and causes a decrease in strain growth at 30 °C. Four thiamine auxotrophic strains were found in subgroup I, while 21 biotin auxotrophic strains were detected in subgroups II. To the best of our knowledge, the spontaneous mutations in F. langsethiae observed in the present work have not been previously reported.

Avoiding dangerous missense: thermophiles display especially low mutation rates.

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John W Drake

2009-06-01

Full Text Available Rates of spontaneous mutation have been estimated under optimal growth conditions for a variety of DNA-based microbes, including viruses, bacteria, and eukaryotes. When expressed as genomic mutation rates, most of the values were in the vicinity of 0.003-0.004 with a range of less than two-fold. Because the genome sizes varied by roughly 10(4-fold, the mutation rates per average base pair varied inversely by a similar factor. Even though the commonality of the observed genomic rates remains unexplained, it implies that mutation rates in unstressed microbes reach values that can be finely tuned by evolution. An insight originating in the 1920s and maturing in the 1960s proposed that the genomic mutation rate would reflect a balance between the deleterious effect of the average mutation and the cost of further reducing the mutation rate. If this view is correct, then increasing the deleterious impact of the average mutation should be countered by reducing the genomic mutation rate. It is a common observation that many neutral or nearly neutral mutations become strongly deleterious at higher temperatures, in which case they are called temperature-sensitive mutations. Recently, the kinds and rates of spontaneous mutations were described for two microbial thermophiles, a bacterium and an archaeon. Using an updated method to extrapolate from mutation-reporter genes to whole genomes reveals that the rate of base substitutions is substantially lower in these two thermophiles than in mesophiles. This result provides the first experimental support for the concept of an evolved balance between the total genomic impact of mutations and the cost of further reducing the basal mutation rate.

INHIBITION OF SPONTANEOUS MUTAGENESIS BY VANILLIN AND CINNAMALDEHYDE IN ESCHERICHIA COLI: DEPENDENCE ON RECOMBINATIONAL REPAIR

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Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that effectively inhibit both induced and spontaneous mutations. We have shown previously that VAN and CIN reduced the spontaneous mutant frequency in Salmonella TA104 (hisG428, rfa, ¿uvrB, pKM101) by approximately...

Influence of uvrB and pKM101 on the spectrum of spontaneous, UV- and gamma-ray-induced base substitutions that revert hisG46 in Salmonella typhimurium

Energy Technology Data Exchange (ETDEWEB)

Eisenstadt, E; Kahng, L -S; Miller, J K; Barnes, W M

1989-01-01

Oligonucleotide probes were used to identify base substitutions in 1089 revertants of hisG46 in Salmonella typhimurium that arose spontaneously or following irradiation with UV- or ..gamma..-rays. The hisG46 allele, carrying a mutant CCC codon (Pro) in place of the wild-type codon CTC (Leu69) reverted via 6 distinguishable mutational events: C to T transitions at codon sites 1 or 2, C to A or C to G transversions at codon site 1, C to A at codon site 2, and an extragenic suppressor mutation. The distribution of hisG46 revertants differed among treatments and was influenced by the DNA-repair capacity of the bacteria. Plasmid pKM101 enhanced the frequencies of both spontaneous adn induced mutations; transversion events were enhanced more efficiently by pKM101 than were transition events. Compared to Uvr/sup +/ bacteria, Uvr/sup -/ bacteria had higher frequencies of spontaneous and induced mutations; transition mutations were enhanced more efficiently than were transversion mutations. The inflence of DNA-repair activiteis on the mutational spectra provides some insights on the origins of spontaneous and UV-induced mutations. (author). 75 refs.; 4 figs.; 4 tabs.

Mutation studies on garden roses: a review

International Nuclear Information System (INIS)

Datta, S.K.

1997-01-01

Most of the modern roses are the result of hybridization, selection and spontaneous mutation. For floriculture trade, there is always demand and necessity for new varieties due to change in taste and fashion. Mutation breeding is an established method for crop improvement. Induced somatic mutation breeding holds promise for effective improvement and have high potential for bringing about genetic improvement and it has led to a great burst of flower colour, form, pattern and other variations in rose by using ionizing radiations. The details of prospects and utilization of induced mutation breeding technique for developing new rose varieties have been compiled. (author)

Radiation-induced mutations in mammals

International Nuclear Information System (INIS)

Ehling, U.H.

1993-01-01

The aims of the proposed project are to provide a better basis for extrapolation of animal data to man. Genetic endpoint, strain and species comparisons are made, which will provide critical experimental data regarding strategies in extrapolating laboratory animal data to man. Experiments were conducted to systematically compare the spontaneous and radiation-induced mutation rates for recessive specific-locus, dominant cataract and enzyme activity alleles in the mouse as well as a comparison of the mutation rate in the mouse and hamster for dominant cataract and enzyme activity alleles. The comparison of the radiation-dose response for recessive specific-locus and dominant cataract mutations are extended. Selected mutations are characterized at the genetic, biochemical and molecular levels. (R.P.) 5 refs., 3 tabs

Association of mutator activity with UV sensitivity in an aphidicolin-resistant mutant of Chinese hamster V79 cells

International Nuclear Information System (INIS)

Liu, P.K.; Chang, C.; Trosko, J.E.

1982-01-01

The spontaneous mutation rates of an ultraviolet light (UV)-sensitive aphidicolin-resistant mutant (aphsup(r)-4-2) and its revertants have been determined by 2 techniques. By using the fluctuation analysis, the mutant and its thymidine (TdR)-prototrophic 'revertant' were found to exhibit elevated spontaneous mutation rates at the 6-thioguanine- and diphtheria-toxin-resistant loci. In contrast, the TdR-auxotrophic 'revertant' did not show this property. Similar results were obtained by the multiple replating technique. From these comparative studies and other previous characterizations, it appears that a single gene mutation is responsible for the following pleiotropic phenotype: slow growth, UV sensitivity, high UV-induced mutability, high frequency of site-specific bromodeoxyuridine (BrdU)-dependent chromosome breaks and enhanced spontaneous mutation rate. Recent studies indicate that the mutation may be on the gene for DNA polymerase α. The results further indicate that thymidine auxotrophy or imbalance in nucleotide pools is not necessarily associated with the mutator activity in mammalian cells. (orig.)

Mutational synergism between p-fluorophenylalaline and UV in Coprinus lagopus

International Nuclear Information System (INIS)

Talmud, P.J.

1977-01-01

The amino acid analogue p-fluorophenylalanine (PFP) is mutagenic to Coprinus lagopus due to its incorporation into proteins. Spontaneous mutations, PFP and UV mutagenesis and PFP/UV synergism have been studied in a UV resistant strain and in two complementing UV sensitive mutant strains. By comparison to the UV resistant strain, one UV sensitive strain shows normal spontaneous mutations, 1.4% PFP-induced mutations and 50-fold UV mutagenesis. The second UV sensitive strain has 19-fold spontaneous mutation frequency and slightly elevated UV mutagenesis. In all 3 strains the PFP/UV synergism is comparable (4-5 times the arithmetic expected). The results indicate that PFP mutagenesis is due to the incorporation of PFP into enzymes normally functioning in the organism but which also participate in UV repair mechanisms. A model is proposed for UV repair which is based on a PFP sensitive excision repair system of at least two enzymes, an alternative 'error-proof' pathway which is not susceptible to PFP and an 'error-prone' pathway which is responsible for UV mutagenesis and is susceptible to PFP as shown by the PFP/UV synergism. Because PFP is given before UV treatment, this implies a UV inducible cofactor and a PFP sensitive enzyme which only functions after UV activation

Spontaneous Chloroplast Mutants Mostly Occur by Replication Slippage and Show a Biased Pattern in the Plastome of Oenothera[OPEN

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Massouh, Amid; Schubert, Julia; Yaneva-Roder, Liliya; Ulbricht-Jones, Elena S.; Johnson, Marc T.J.; Wright, Stephen I.; Pellizzer, Tommaso; Sobanski, Johanna; Greiner, Stephan

2016-01-01

Spontaneous plastome mutants have been used as a research tool since the beginning of genetics. However, technical restrictions have severely limited their contributions to research in physiology and molecular biology. Here, we used full plastome sequencing to systematically characterize a collection of 51 spontaneous chloroplast mutants in Oenothera (evening primrose). Most mutants carry only a single mutation. Unexpectedly, the vast majority of mutations do not represent single nucleotide polymorphisms but are insertions/deletions originating from DNA replication slippage events. Only very few mutations appear to be caused by imprecise double-strand break repair, nucleotide misincorporation during replication, or incorrect nucleotide excision repair following oxidative damage. U-turn inversions were not detected. Replication slippage is induced at repetitive sequences that can be very small and tend to have high A/T content. Interestingly, the mutations are not distributed randomly in the genome. The underrepresentation of mutations caused by faulty double-strand break repair might explain the high structural conservation of seed plant plastomes throughout evolution. In addition to providing a fully characterized mutant collection for future research on plastid genetics, gene expression, and photosynthesis, our work identified the spectrum of spontaneous mutations in plastids and reveals that this spectrum is very different from that in the nucleus. PMID:27053421

Ziprasidone-induced spontaneous orgasm.

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Boora, K; Chiappone, K; Dubovsky, S; Xu, J

2010-06-01

Neuroleptic treatment in schizophrenic patients has been associated with sexual dysfunction, including impotence and decreased libido. Spontaneous ejaculation without sexual arousal during typical antipsychotic treatment is a rare condition that has been described with zuclopentixol, trifluoperazine, and thiothixene. Here, we are reporting a case of spontaneous orgasm with ziprasidone in a bipolar patient. This patient began to repeatedly experience spontaneous sexual arousal and orgasm, which she had never experienced in the past. Ziprasidone might be causing an increase in sexual orgasm by 5-HT2 receptor antagonism, which preclinical evidence suggests that it facilitates dopamine release in the cortex.

Molecular Clock of Neutral Mutations in a Fitness-Increasing Evolutionary Process.

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Kishimoto, Toshihiko; Ying, Bei-Wen; Tsuru, Saburo; Iijima, Leo; Suzuki, Shingo; Hashimoto, Tomomi; Oyake, Ayana; Kobayashi, Hisaka; Someya, Yuki; Narisawa, Dai; Yomo, Tetsuya

2015-07-01

The molecular clock of neutral mutations, which represents linear mutation fixation over generations, is theoretically explained by genetic drift in fitness-steady evolution or hitchhiking in adaptive evolution. The present study is the first experimental demonstration for the molecular clock of neutral mutations in a fitness-increasing evolutionary process. The dynamics of genome mutation fixation in the thermal adaptive evolution of Escherichia coli were evaluated in a prolonged evolution experiment in duplicated lineages. The cells from the continuously fitness-increasing evolutionary process were subjected to genome sequencing and analyzed at both the population and single-colony levels. Although the dynamics of genome mutation fixation were complicated by the combination of the stochastic appearance of adaptive mutations and clonal interference, the mutation fixation in the population was simply linear over generations. Each genome in the population accumulated 1.6 synonymous and 3.1 non-synonymous neutral mutations, on average, by the spontaneous mutation accumulation rate, while only a single genome in the population occasionally acquired an adaptive mutation. The neutral mutations that preexisted on the single genome hitchhiked on the domination of the adaptive mutation. The successive fixation processes of the 128 mutations demonstrated that hitchhiking and not genetic drift were responsible for the coincidence of the spontaneous mutation accumulation rate in the genome with the fixation rate of neutral mutations in the population. The molecular clock of neutral mutations to the fitness-increasing evolution suggests that the numerous neutral mutations observed in molecular phylogenetic trees may not always have been fixed in fitness-steady evolution but in adaptive evolution.

Molecular Clock of Neutral Mutations in a Fitness-Increasing Evolutionary Process.

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Toshihiko Kishimoto

2015-07-01

Full Text Available The molecular clock of neutral mutations, which represents linear mutation fixation over generations, is theoretically explained by genetic drift in fitness-steady evolution or hitchhiking in adaptive evolution. The present study is the first experimental demonstration for the molecular clock of neutral mutations in a fitness-increasing evolutionary process. The dynamics of genome mutation fixation in the thermal adaptive evolution of Escherichia coli were evaluated in a prolonged evolution experiment in duplicated lineages. The cells from the continuously fitness-increasing evolutionary process were subjected to genome sequencing and analyzed at both the population and single-colony levels. Although the dynamics of genome mutation fixation were complicated by the combination of the stochastic appearance of adaptive mutations and clonal interference, the mutation fixation in the population was simply linear over generations. Each genome in the population accumulated 1.6 synonymous and 3.1 non-synonymous neutral mutations, on average, by the spontaneous mutation accumulation rate, while only a single genome in the population occasionally acquired an adaptive mutation. The neutral mutations that preexisted on the single genome hitchhiked on the domination of the adaptive mutation. The successive fixation processes of the 128 mutations demonstrated that hitchhiking and not genetic drift were responsible for the coincidence of the spontaneous mutation accumulation rate in the genome with the fixation rate of neutral mutations in the population. The molecular clock of neutral mutations to the fitness-increasing evolution suggests that the numerous neutral mutations observed in molecular phylogenetic trees may not always have been fixed in fitness-steady evolution but in adaptive evolution.

Exploring the common molecular basis for the universal DNA mutation bias: Revival of Loewdin mutation model

International Nuclear Information System (INIS)

Fu, Liang-Yu; Wang, Guang-Zhong; Ma, Bin-Guang; Zhang, Hong-Yu

2011-01-01

Highlights: → There exists a universal G:C → A:T mutation bias in three domains of life. → This universal mutation bias has not been sufficiently explained. → A DNA mutation model proposed by Loewdin 40 years ago offers a common explanation. -- Abstract: Recently, numerous genome analyses revealed the existence of a universal G:C → A:T mutation bias in bacteria, fungi, plants and animals. To explore the molecular basis for this mutation bias, we examined the three well-known DNA mutation models, i.e., oxidative damage model, UV-radiation damage model and CpG hypermutation model. It was revealed that these models cannot provide a sufficient explanation to the universal mutation bias. Therefore, we resorted to a DNA mutation model proposed by Loewdin 40 years ago, which was based on inter-base double proton transfers (DPT). Since DPT is a fundamental and spontaneous chemical process and occurs much more frequently within GC pairs than AT pairs, Loewdin model offers a common explanation for the observed universal mutation bias and thus has broad biological implications.

Spontaneous Chloroplast Mutants Mostly Occur by Replication Slippage and Show a Biased Pattern in the Plastome of Oenothera.

Science.gov (United States)

Massouh, Amid; Schubert, Julia; Yaneva-Roder, Liliya; Ulbricht-Jones, Elena S; Zupok, Arkadiusz; Johnson, Marc T J; Wright, Stephen I; Pellizzer, Tommaso; Sobanski, Johanna; Bock, Ralph; Greiner, Stephan

2016-04-01

Spontaneous plastome mutants have been used as a research tool since the beginning of genetics. However, technical restrictions have severely limited their contributions to research in physiology and molecular biology. Here, we used full plastome sequencing to systematically characterize a collection of 51 spontaneous chloroplast mutants in Oenothera (evening primrose). Most mutants carry only a single mutation. Unexpectedly, the vast majority of mutations do not represent single nucleotide polymorphisms but are insertions/deletions originating from DNA replication slippage events. Only very few mutations appear to be caused by imprecise double-strand break repair, nucleotide misincorporation during replication, or incorrect nucleotide excision repair following oxidative damage. U-turn inversions were not detected. Replication slippage is induced at repetitive sequences that can be very small and tend to have high A/T content. Interestingly, the mutations are not distributed randomly in the genome. The underrepresentation of mutations caused by faulty double-strand break repair might explain the high structural conservation of seed plant plastomes throughout evolution. In addition to providing a fully characterized mutant collection for future research on plastid genetics, gene expression, and photosynthesis, our work identified the spectrum of spontaneous mutations in plastids and reveals that this spectrum is very different from that in the nucleus. © 2016 American Society of Plant Biologists. All rights reserved.

Genome-Wide Mutation Rate Response to pH Change in the Coral Reef Pathogen Vibrio shilonii AK1.

Science.gov (United States)

Strauss, Chloe; Long, Hongan; Patterson, Caitlyn E; Te, Ronald; Lynch, Michael

2017-08-22

Recent application of mutation accumulation techniques combined with whole-genome sequencing (MA/WGS) has greatly promoted studies of spontaneous mutation. However, such explorations have rarely been conducted on marine organisms, and it is unclear how marine habitats have influenced genome stability. This report resolves the mutation rate and spectrum of the coral reef pathogen Vibrio shilonii , which causes coral bleaching and endangers the biodiversity maintained by coral reefs. We found that its mutation rate and spectrum are highly similar to those of other studied bacteria from various habitats, despite the saline environment. The mutational properties of this marine bacterium are thus controlled by other general evolutionary forces such as natural selection and genetic drift. We also found that as pH drops, the mutation rate decreases and the mutation spectrum is biased in the direction of generating G/C nucleotides. This implies that evolutionary features of this organism and perhaps other marine microbes might be altered by the increasingly acidic ocean water caused by excess CO 2 emission. Nonetheless, further exploration is needed as the pH range tested in this study was rather narrow and many other possible mutation determinants, such as carbonate increase, are associated with ocean acidification. IMPORTANCE This study explored the pH dependence of a bacterial genome-wide mutation rate. We discovered that the genome-wide rates of appearance of most mutation types decrease linearly and that the mutation spectrum is biased in generating more G/C nucleotides with pH drop in the coral reef pathogen V. shilonii . Copyright © 2017 Strauss et al.

Heterozygous congenital Factor VII deficiency with the 9729del4 mutation, associated with severe spontaneous intracranial bleeding in an adolescent male.

Science.gov (United States)

Cramer, Thomas J; Anderson, Kristin; Navaz, Karanjia; Brown, Justin M; Mosnier, Laurent O; von Drygalski, Annette

2016-03-01

In congenital Factor (F) VII deficiency bleeding phenotype and intrinsic FVII activity levels don't always correlate. Patients with FVII activity levels <30% appear to have a higher bleeding propensity, but bleeding can also occur at higher FVII activity levels. Reasons for bleeding at higher FVII activity levels are unknown, and it remains challenging to manage such patients clinically. A 19year old male with spontaneous intracranial hemorrhage and FVII activity levels of 44%, requiring emergent surgical intervention and a strategy for FVII replacement. Genotyping showed the rare heterozygous FVII 9729del4 mutation. Bleed evacuation was complicated by epidural abscess requiring craniectomy, bone graft procedures, and prolonged administration of recombinant human (rh) activated FVII (FVIIa). The patient recovered without neurological deficits, and remains on prophylactic low dose treatment with rhFVIIa in relation to risky athletic activities. For clinicians, it is important to recognize that effects of rhFVIIa within these pathways are independent of its contribution to blood clot formation and cannot be assessed by clotting assays. Reduced FVII levels should therefore not be dismissed, as even a mild reduction may result in spontaneous bleeding. Treatment of mild FVII deficiency requires a careful case-by-case approach, based on the clinical scenario. Copyright © 2015 Elsevier Inc. All rights reserved.

Rhynchophylla total alkaloid rescues autophagy, decreases oxidative stress and improves endothelial vasodilation in spontaneous hypertensive rats.

Science.gov (United States)

Li, Chao; Jiang, Feng; Li, Yun-Lun; Jiang, Yue-Hua; Yang, Wen-Qing; Sheng, Jie; Xu, Wen-Juan; Zhu, Qing-Jun

2018-03-01

Autophagy plays an important role in alleviating oxidative stress and stabilizing atherosclerotic plaques. However, the potential role of autophagy in endothelial vasodilation function has rarely been studied. This study aimed to investigate whether rhynchophylla total alkaloid (RTA) has a positive role in enhancing autophagy through decreasing oxidative stress, and improving endothelial vasodilation. In oxidized low-density lipoprotein (ox-LDL)-treated human umbilical vein endothelial cells (HUVECs), RTA (200 mg/L) significantly suppressed ox-LDL-induced oxidative stress through rescuing autophagy, and decreased cell apoptosis. In spontaneous hypertensive rats (SHR), administration of RTA (50 mg·kg -1 ·d -1 , ip, for 6 weeks) improved endothelin-dependent vasodilation of thoracic aorta rings. Furthermore, RTA administration significantly increased the antioxidant capacity and alleviated oxidative stress through enhancing autophagy in SHR. In ox-LDL-treated HUVECs, we found that the promotion of autophagy by RTA resulted in activation of the AMP-activated protein kinase (AMPK) signaling pathway. Our results show that RTA treatment rescues the ox-LDL-induced autophagy impairment in HUVECs and improves endothelium-dependent vasodilation function in SHR.

A nonsense mutation causing decreased levels of insulin receptor mRNA: Detection by a simplified technique for direct sequencing of genomic DNA amplified by the polymerase chain reaction

International Nuclear Information System (INIS)

Kadowaki, T.; Kadowaki, H.; Taylor, S.I.

1990-01-01

Mutations in the insulin receptor gene can render the cell resistant to the biological action of insulin. The authors have studied a patient with leprechaunism (leprechaun/Minn-1), a genetic syndrome associated with intrauterine growth retardation and extreme insulin resistance. Genomic DNA from the patient was amplified by the polymerase chain reaction catalyzed by Thermus aquaticus (Taq) DNA polymerase, and the amplified DNA was directly sequenced. A nonsense mutations was identified at codon 897 in exon 14 in the paternal allele of the patient's insulin receptor gene. Levels of insulin receptor mRNA are decreased to <10% of normal in Epstein-Barr virus-transformed lymphoblasts and cultured skin fibroblasts from this patient. Thus, this nonsense mutation appears to cause a decrease in the levels of insulin receptor mRNA. In addition, they have obtained indirect evidence that the patient's maternal allele of the insulin receptor gene contains a cis-acting dominant mutation that also decreases the level of mRNA, but by a different mechanism. The nucleotide sequence of the entire protein-coding domain and the sequences of the intron-exon boundaries for all 22 exons of the maternal allele were normal. Presumably, the mutation in the maternal allele maps elsewhere in the insulin receptor gene. Thus, they conclude that the patient is a compound heterozygote for two cis-acting dominant mutations in the insulin receptor gene: (i) a nonsense mutation in the paternal allel that reduces the level of insulin receptor mRNA and (ii) an as yet unidentified mutation in the maternal allele that either decreases the rate of transcription or decreases the stability of the mRNA

Cytosine deamination and the precipitous decline of spontaneous mutation during Earth's history.

Science.gov (United States)

Lewis, Charles A; Crayle, Jesse; Zhou, Shuntai; Swanstrom, Ronald; Wolfenden, Richard

2016-07-19

The hydrolytic deamination of cytosine and 5-methylcytosine residues in DNA appears to contribute significantly to the appearance of spontaneous mutations in microorganisms and in human disease. In the present work, we examined the mechanism of cytosine deamination and the response of the uncatalyzed reaction to changing temperature. The positively charged 1,3-dimethylcytosinium ion was hydrolyzed at a rate similar to the rate of acid-catalyzed hydrolysis of 1-methylcytosine, for which it furnishes a satisfactory kinetic model and a probable mechanism. In agreement with earlier reports, uncatalyzed deamination was found to proceed at very similar rates for cytosine, 1-methylcytosine, cytidine, and cytidine 5'-phosphate, and also for cytosine residues in single-stranded DNA generated from a phagemid, in which we sequenced an insert representing the gene of the HIV-1 protease. Arrhenius plots for the uncatalyzed deamination of cytosine were linear over the temperature range from 90 °C to 200 °C and indicated a heat of activation (ΔH(‡)) of 23.4 ± 0.5 kcal/mol at pH 7. Recent evidence indicates that the surface of the earth has been cool enough to support life for more than 4 billion years and that life has been present for almost as long. If the temperature at Earth's surface is assumed to have followed Newton's law of cooling, declining exponentially from 100 °C to 25 °C during that period, then half of the cytosine-deaminating events per unit biomass would have taken place during the first 0.2 billion years, and <99.4% would have occurred during the first 2 billion years.

Decreased numbers of chemotactic factor receptors in chronic neutropenia with defective chemotaxis: spontaneous recovery from the neutrophil abnormalities during early childhood

International Nuclear Information System (INIS)

Yasui, K.; Yamazaki, M.; Miyagawa, Y.; Komiyama, A.; Akabane, T.

1987-01-01

Childhood chronic neutropenia with decreased numbers of chemotactic factor receptors as well as defective chemotaxis was first demonstrated in an 8-month-old girl. Chemotactic factor receptors on neutrophils were assayed using tritiated N-formyl-methionyl-leucyl-phenylalanine ( 3 H-FMLP). The patient's neutrophils had decreased numbers of the receptors: numbers of the receptors were 20,000 (less than 3 SD) as compared with those of control cells of 52,000 +/- 6000 (mean +/- SD) (n = 10). The neutropenia disappeared spontaneously by 28 months of age parallel with the improvement of chemotaxis and increase in numbers of chemotactic factor receptors. These results demonstrate a transient decrease of neutrophil chemotactic factor receptors as one of the pathophysiological bases of a transient defect of neutrophil chemotaxis in this disorder

Effects of harman and norharman on spontaneous and ultraviolet light-induced mutagenesis in cultured Chinese hamster cells

International Nuclear Information System (INIS)

Chang, C.C.; Castellazzi, M.; Glover, T.W.; Trosko, J.E.

1978-01-01

Nontoxic concentrations of harman and norharman were tested in cultured Chinese hamster cells for their effects on DNA repair and mutagenesis. The following effects of harman were observed: (a) the survival of ultraviolet light- or x-ray-damaged cells was reduced; (b) the ultraviolet light-induced unscheduled DNA synthesis was slightly inhibited; and (c) the frequency of spontaneous or ultraviolet light-induced ouabain-resistant (ouar) or 6-thioguanine-resistant (6-TGr) mutations was reduced. Furthermore, the effect of harman on survival and mutagenesis was greater than that of norharman and was detected primarily in treatments in which cells were exposed to harman immediately following ultraviolet light irradiation. Our data clearly indicate that harman decreases the capacity to repair DNA damage and fix mutations in Chinese hamster cells, possibly because of the intercalation properties of this compound

Reproductive Decision-Making in MMR Mutation Carriers After Results Disclosure: Impact of Psychological Status in Childbearing Options.

Science.gov (United States)

Duffour, Jacqueline; Combes, Audrey; Crapez, Evelyne; Boissière-Michot, Florence; Bibeau, Frédéric; Senesse, Pierre; Ychou, Marc; Courraud, Julie; de Forges, Hélène; Roca, Lise

2016-06-01

Reproductive techniques such as prenatal diagnosis (PND) or preimplantation genetic diagnosis (PGD), although debated, are legally forbidden in France in case of Lynch syndrome. The preference of mutation carriers about their reproductive options is not systematically considered in France. We aimed to prospectively assess the reproductive preferences of mismatch repair mutation carriers consulting in our institution (2003-2010, n = 100). We also considered the short- and long-term post-disclosure psychological impact using the Impact of Events Scale-Revised questionnaire to measure the prevalence of posttraumatic stress disorder (PTSD) in those patients. Complete data were obtained for 34 respondents (17 males, 17 females, median age of 33.5 years [22-59]). Seventeen respondents (57 %) preferred spontaneous natural conception versus 28 % and 35 % choosing PND and PGD, respectively. At results disclosure, respondents mainly explained their distress by fear of premature death (43 %) and transmitting mutated genes (42 %). One year later, this last fear remained predominant in 55 % of subjects. None of the main socio-demographical, psychological or medical variables (including fear of transmitting mutations) was significantly associated with the reproductive preferences. Results disclosure had a real and time-decreasing psychological impact on mutation carriers. Reproductive techniques, expected to decrease the hereditary risk, were not significantly preferred to natural conception.

Mutation in HFE gene decreases manganese accumulation and oxidative stress in the brain after olfactory manganese exposure.

Science.gov (United States)

Ye, Qi; Kim, Jonghan

2016-06-01

Increased accumulation of manganese (Mn) in the brain is significantly associated with neurobehavioral deficits and impaired brain function. Airborne Mn has a high systemic bioavailability and can be directly taken up into the brain, making it highly neurotoxic. While Mn transport is in part mediated by several iron transporters, the expression of these transporters is altered by the iron regulatory gene, HFE. Mutations in the HFE gene are the major cause of the iron overload disorder, hereditary hemochromatosis, one of the prevalent genetic diseases in humans. However, whether or not HFE mutation modifies Mn-induced neurotoxicity has not been evaluated. Therefore, our goal was to define the role of HFE mutation in Mn deposition in the brain and the resultant neurotoxic effects after olfactory Mn exposure. Mice carrying the H67D HFE mutation, which is homologous to the H63D mutation in humans, and their control, wild-type mice, were intranasally instilled with MnCl2 with different doses (0, 0.2, 1.0 and 5.0 mg kg(-1)) daily for 3 days. Mn levels in the blood, liver and brain were determined using inductively-coupled plasma mass spectrometry (ICP-MS). H67D mutant mice showed significantly lower Mn levels in the blood, liver, and most brain regions, especially in the striatum, while mice fed an iron-overload diet did not. Moreover, mRNA expression of ferroportin, an essential exporter of iron and Mn, was up-regulated in the striatum. In addition, the levels of isoprostane, a marker of lipid peroxidation, were increased in the striatum after Mn exposure in wild-type mice, but were unchanged in H67D mice. Together, our results suggest that the H67D mutation provides decreased susceptibility to Mn accumulation in the brain and neurotoxicity induced by inhaled Mn.

Molecular and biochemical analyses of spontaneous and X-ray-induced mutants in human lymphoblastoid cells

Energy Technology Data Exchange (ETDEWEB)

Liber, H L; Call, K M; Little, J B

1987-05-01

The authors have isolated a series of 14 spontaneously arising and 28 X-ray-induced mutants at the hypoxanthine-guanine phosphoribosyltransferase (hgprt) locus in human lymphoblastoid cells. Among the spontaneous mutants, 5/14 (36%) had detectable alterations in their restriction fragment pattern after hybridization with a human cDNA probe for hgprt. Of the 10 remaining mutants, 4 had partial HGPRT enzyme activity, which suggested that they contained point mutations. Among the 28 mutants induced by 150 rad of X-rays, 15 (54%) had deletions of part or all of the hgprt gene. Of the remaining 13 (18% overall) 5 had partial HGPRT enzyme activity, which suggested that they contained point mutations. These data imply that in this human cell system, X-rays induce both point mutants which have residual enzyme activity as well as mutations involving relatively large deletions of DNA. 48 reference, 1 figure, 4 tables.

Deficiency of the DNA repair protein nibrin increases the basal but not the radiation induced mutation frequency in vivo

International Nuclear Information System (INIS)

Wessendorf, Petra; Vijg, Jan; Nussenzweig, André; Digweed, Martin

2014-01-01

Highlights: • lacZ mutant frequencies measured in vivo in mouse models of radiosensitive Nijmegen Breakage Syndrome. • Spontaneous mutation frequencies are increased in lymphatic tissue due to Nbn mutation. • Single base transitions, not deletions, dominate the mutation spectrum. • Radiation induced mutation frequencies are not increased due to Nbn mutation. - Abstract: Nibrin (NBN) is a member of a DNA repair complex together with MRE11 and RAD50. The complex is associated particularly with the repair of DNA double strand breaks and with the regulation of cell cycle check points. Hypomorphic mutation of components of the complex leads to human disorders characterised by radiosensitivity and increased tumour occurrence, particularly of the lymphatic system. We have examined here the relationship between DNA damage, mutation frequency and mutation spectrum in vitro and in vivo in mouse models carrying NBN mutations and a lacZ reporter plasmid. We find that NBN mutation leads to increased spontaneous DNA damage in fibroblasts in vitro and high basal mutation rates in lymphatic tissue of mice in vivo. The characteristic mutation spectrum is dominated by single base transitions rather than the deletions and complex rearrangements expected after abortive repair of DNA double strand breaks. We conclude that in the absence of wild type nibrin, the repair of spontaneous errors, presumably arising during DNA replication, makes a major contribution to the basal mutation rate. This applies also to cells heterozygous for an NBN null mutation. Mutation frequencies after irradiation in vivo were not increased in mice with nibrin mutations as might have been expected considering the radiosensitivity of NBS patient cells in vitro. Evidently apoptosis is efficient, even in the absence of wild type nibrin

Deficiency of the DNA repair protein nibrin increases the basal but not the radiation induced mutation frequency in vivo

Energy Technology Data Exchange (ETDEWEB)

Wessendorf, Petra [Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany); Vijg, Jan [Albert Einstein College of Medicine, Michael F. Price Center, 1301 Morris Park Avenue, Bronx, NY 10461 (United States); Nussenzweig, André [Laboratory of Genome Integrity, National Cancer Institute, National Institute of Health, 37 Convent Drive, Room 1106, Bethesda, MD 20892 (United States); Digweed, Martin, E-mail: martin.digweed@charite.de [Institute of Medical and Human Genetics, Charité – Universitätsmedizin Berlin, Augustenburger Platz 1, D-13353 Berlin (Germany)

2014-11-15

Highlights: • lacZ mutant frequencies measured in vivo in mouse models of radiosensitive Nijmegen Breakage Syndrome. • Spontaneous mutation frequencies are increased in lymphatic tissue due to Nbn mutation. • Single base transitions, not deletions, dominate the mutation spectrum. • Radiation induced mutation frequencies are not increased due to Nbn mutation. - Abstract: Nibrin (NBN) is a member of a DNA repair complex together with MRE11 and RAD50. The complex is associated particularly with the repair of DNA double strand breaks and with the regulation of cell cycle check points. Hypomorphic mutation of components of the complex leads to human disorders characterised by radiosensitivity and increased tumour occurrence, particularly of the lymphatic system. We have examined here the relationship between DNA damage, mutation frequency and mutation spectrum in vitro and in vivo in mouse models carrying NBN mutations and a lacZ reporter plasmid. We find that NBN mutation leads to increased spontaneous DNA damage in fibroblasts in vitro and high basal mutation rates in lymphatic tissue of mice in vivo. The characteristic mutation spectrum is dominated by single base transitions rather than the deletions and complex rearrangements expected after abortive repair of DNA double strand breaks. We conclude that in the absence of wild type nibrin, the repair of spontaneous errors, presumably arising during DNA replication, makes a major contribution to the basal mutation rate. This applies also to cells heterozygous for an NBN null mutation. Mutation frequencies after irradiation in vivo were not increased in mice with nibrin mutations as might have been expected considering the radiosensitivity of NBS patient cells in vitro. Evidently apoptosis is efficient, even in the absence of wild type nibrin.

Somatic mutation frequencies in the stamen hairs of stable and mutable clones of Tradescantia after acute gamma-ray treatments with small doses

International Nuclear Information System (INIS)

Ichikawa, Sadao; Takahashi, C.S.

1977-01-01

Young inflorescences of two different Tradescantia clones heterozygous for flower and stamen-hair color, one stable (KU 9) and the other spontaneously mutable (KU 20), were irradiated acutely with small doses (approx. 3 to 50 R) of 60 Co gamma-rays. Somatic mutation frequencies from blue to pink in the stamen hairs scored on post-irradiation days 10 to 16 increased essentially linearly with increasing gamma-ray dose in both clones. Despite about a 5-fold difference in spontaneous mutation frequency per hair found between the two clones, the dose-response curves of pink mutations determined were similar to each other, giving average mutation frequencies of 1.51 and 1.41 pink-mutant events per 1000 hairs per R for KU 9 and KU 20, respectively. These frequencies are comparable to earlier results obtained from acute irradiation treatments of other clones with higher doses. The doubling dose of pink mutation (the radiation dose making the mutation frequency double the spontaneous level) was calculated to be 2.09 R for KU 9, and this low doubling dose must be given full attention. On the other hand, the doubling dose for KU 20 (calculated to be 10.4 R) is of questionable value, being greatly subject to change because of the diversely variable spontaneous mutation frequency of this clone

The calreticulin (CALR) exon 9 mutations are promising targets for cancer immune therapy

DEFF Research Database (Denmark)

Holmström, M O; Martinenaite, E; Ahmad, S M

2017-01-01

The calreticulin (CALR) exon 9 mutations are found in ∼30% of patients with essential thrombocythemia and primary myelofibrosis. Recently, we reported spontaneous immune responses against the CALR mutations. Here, we describe that CALR-mutant (CALRmut)-specific T cells are able to specifically re...... CALR exon 9 mutations.Leukemia advance online publication, 15 August 2017; doi:10.1038/leu.2017.214....

Interactions Between SNAP-25 and Synaptotagmin-1 Are Involved in Vesicle Priming, Clamping Spontaneous and Stimulating Evoked Neurotransmission

DEFF Research Database (Denmark)

Schupp, Melanie; Malsam, Jörg; Ruiter, Marvin

2016-01-01

between region I (vesicle priming) and region II (evoked release). Spontaneous release was disinhibited by region I mutations and found to correlate with defective complexin (Cpx) clamping in an in vitro fusion assay, pointing to an interdependent role of synaptotagmin and Cpx in release clamping...... triggering, depend on direct SNARE complex interaction. SIGNIFICANCE STATEMENT: The function of synaptotagmin-1 (syt-1):soluble NSF attachment protein receptor (SNARE) interactions during neurotransmission remains unclear. We mutated SNAP-25 within the recently identified region I and region II...... was disinhibited by region I mutation and found to correlate with defective complexin (Cpx) clamping in vitro, pointing to an interdependent role of synaptotagmin and Cpx in release clamping. Therefore, vesicle priming, clamping spontaneous release, and eliciting evoked release are three different functions of syt...

Depolarized inactivation overcomes impaired activation to produce DRG neuron hyperexcitability in a Nav1.7 mutation in a patient with distal limb pain.

Science.gov (United States)

Huang, Jianying; Yang, Yang; Dib-Hajj, Sulayman D; van Es, Michael; Zhao, Peng; Salomon, Jody; Drenth, Joost P H; Waxman, Stephen G

2014-09-10

Sodium channel Nav1.7, encoded by SCN9A, is expressed in DRG neurons and regulates their excitability. Genetic and functional studies have established a critical contribution of Nav1.7 to human pain disorders. We have now characterized a novel Nav1.7 mutation (R1279P) from a female human subject with distal limb pain, in which depolarized fast inactivation overrides impaired activation to produce hyperexcitability and spontaneous firing in DRG neurons. Whole-cell voltage-clamp recordings in human embryonic kidney (HEK) 293 cells demonstrated that R1279P significantly depolarizes steady-state fast-, slow-, and closed-state inactivation. It accelerates deactivation, decelerates inactivation, and facilitates repriming. The mutation increases ramp currents in response to slow depolarizations. Our voltage-clamp analysis showed that R1279P depolarizes channel activation, a change that was supported by our multistate structural modeling. Because this mutation confers both gain-of-function and loss-of-function attributes on the Nav1.7 channel, we tested the impact of R1279P expression on DRG neuron excitability. Current-clamp studies reveal that R1279P depolarizes resting membrane potential, decreases current threshold, and increases firing frequency of evoked action potentials within small DRG neurons. The populations of spontaneously firing and repetitively firing neurons were increased by expressing R1279P. These observations indicate that the dominant proexcitatory gating changes associated with this mutation, including depolarized steady-state fast-, slow-, and closed-state inactivation, faster repriming, and larger ramp currents, override the depolarizing shift of activation, to produce hyperexcitability and spontaneous firing of nociceptive neurons that underlie pain. Copyright © 2014 the authors 0270-6474/14/3412328-13$15.00/0.

Chloroplast mutations induced by 9-aminoacridine hydrochloride are independent of the plastome mutator in Oenothera.

Science.gov (United States)

GuhaMajumdar, M; Baldwin, S; Sears, B B

2004-02-01

Oenothera plants homozygous for the recessive plastome mutator allele ( pm) show chloroplast DNA (cpDNA) mutation frequencies that are about 1,000-fold higher than spontaneous levels. The pm-encoded gene product has been hypothesized to have a function in cpDNA replication, repair and/or mutation avoidance. Previous chemical mutagenesis experiments with the alkylating agent nitroso-methyl urea (NMU) showed a synergistic effect of NMU on the induction of mutations in the pm line, suggesting an interaction between the pm-encoded gene product and one of the repair systems that corrects alkylation damage. The goal of the experiments described here was to examine whether the pm activity extends to the repair of damage caused by non-alkylating mutagens. To this end, the intercalating mutagen, 9-aminoacridine hydrochloride (9AA) was tested for synergism with the plastome mutator. A statistical analysis of the data reported here indicates that the pm-encoded gene product is not involved in the repair of the 9AA-induced mutations. However, the recovery of chlorotic sectors in plants derived from the mutagenized seeds shows that 9AA can act as a mutagen of the chloroplast genome.

Mutation frequencies in male mice and the estimation of genetic hazards of radiation in men

International Nuclear Information System (INIS)

Russell, W.L.; Kelly, E.M.

1982-01-01

Estimation of the genetic hazards of ionizing radiation in men is based largely on the frequency of transmitted specific-locus mutations induced in mouse spermatogonial stem cells at low radiation dose rates. The publication of new data on this subject has permitted a fresh review of all the information available. The data continue to show no discrepancy from the interpretation that, although mutation frequency decreases markedly as dose rate is decreased from 90 to 0.8 R/min (1 R = 2.6 x 10/sup -4/ coulombs/kg) there seems to be no further change below 0.8 R/min over the range from that dose rate to 0.0007 R/min. Simple mathematical models are used to compute: (a) a maximum likelihood estimate of the induced mutation frequency at the low dose rates, and (b) a maximum likelihood estimate of the ratio of this to the mutation frequency at high dose rates in the range of 72 to 90 R/min. In the application of these results to the estimation of genetic hazards of radiation in man, the former value can be used to calcualte a doubling dose - i.e., the dose of radiation that induces a mutation frequency equal to the spontaneous frequency. The doubling dose based on the low-dose-rate data compiled here is 110 R. The ratio of the mutation frequency at low dose rate to to that at high dose rate is useful when it becomes necessary to extrapolate from experimental determinations, or from human data, at high dose rates to the expected risk at low dose rates. The ratio derived from the present analysis is 0.33

Induction of somatic mutations by low-dose X-rays: the challenge in recognizing radiation-induced events.

Science.gov (United States)

Nagashima, Haruki; Shiraishi, Kumiko; Ohkawa, Saori; Sakamoto, Yuki; Komatsu, Kenshi; Matsuura, Shinya; Tachibana, Akira; Tauchi, Hiroshi

2017-10-19

It is difficult to distinguish radiation-induced events from spontaneous events during induction of stochastic effects, especially in the case of low-dose or low-dose-rate exposures. By using a hypersensitive system for detecting somatic mutations at the HPRT1 locus, we investigated the frequency and spectrum of mutations induced by low-dose X-rays. The mutant frequencies induced by doses of >0.15 Gy were statistically significant when compared with the spontaneous frequency, and a clear dose dependency was also observed for mutant frequencies at doses of >0.15 Gy. In contrast, mutant frequencies at doses of 0.2 Gy. Our observations suggest that there could be a critical dose for mutation induction at between 0.1 Gy and 0.2 Gy, where mutagenic events are induced by multiple DNA double-strand breaks (DSBs). These observations also suggest that low-dose radiation delivered at doses of <0.1 Gy may not result in DSB-induced mutations but may enhance spontaneous mutagenesis events. © The Author 2017. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.

A new human NHERF1 mutation decreases renal phosphate transporter NPT2a expression by a PTH-independent mechanism.

Directory of Open Access Journals (Sweden)

Marie Courbebaisse

Full Text Available BACKGROUND: The sodium-hydrogen exchanger regulatory factor 1 (NHERF1 binds to the main renal phosphate transporter NPT2a and to the parathyroid hormone (PTH receptor. We have recently identified mutations in NHERF1 that decrease renal phosphate reabsorption by increasing PTH-induced cAMP production in the renal proximal tubule. METHODS: We compared relevant parameters of phosphate homeostasis in a patient with a previously undescribed mutation in NHERF1 and in control subjects. We expressed the mutant NHERF1 protein in Xenopus Oocytes and in cultured cells to study its effects on phosphate transport and PTH-induced cAMP production. RESULTS: We identified in a patient with inappropriate renal phosphate reabsorption a previously unidentified mutation (E68A located in the PDZ1 domain of NHERF1.We report the consequences of this mutation on NHERF1 function. E68A mutation did not modify cAMP production in the patient. PTH-induced cAMP synthesis and PKC activity were not altered by E68A mutation in renal cells in culture. In contrast to wild-type NHERF1, expression of the E68A mutant in Xenopus oocytes and in human cells failed to increase phosphate transport. Pull down experiments showed that E68A mutant did not interact with NPT2a, which robustly interacted with wild type NHERF1 and previously identified mutants. Biotinylation studies revealed that E68A mutant was unable to increase cell surface expression of NPT2a. CONCLUSIONS: Our results indicate that the PDZ1 domain is critical for NHERF1-NPT2a interaction in humans and for the control of NPT2a expression at the plasma membrane. Thus we have identified a new mechanism of renal phosphate loss and shown that different mutations in NHERF1 can alter renal phosphate reabsorption via distinct mechanisms.

Effects of Mutagen-Sensitive Mus Mutations on Spontaneous Mitotic Recombination in Aspergillus

OpenAIRE

Zhao, P.; Kafer, E.

1992-01-01

Methyl methane-sulfonate (MMS)-sensitive, radiation-induced mutants of Aspergillus were shown to define nine new DNA repair genes, musK to musS. To test mus mutations for effects on mitotic recombination, intergenic crossing over was assayed between color markers and their centromeres, and intragenic recombination between two distinguishable adE alleles. Of eight mutants analyzed, four showed significant deviations from mus(+) controls in both tests. Two mutations, musK and musL, reduced reco...

Age-related increase in the rate of spontaneou and γ-ray-induced hprt mutations in mouse spleen lymphocytes

International Nuclear Information System (INIS)

Gazlev, A.I.; Podlutskii, A.Ya.; Bradbury, R.

1994-01-01

Endogenous and exogenous factors continually afflict DNA of cells of organisms. A certain amount of the damage is accumulated causing mutations, increasing the risk of malignacies, impairing cell functions, and upsetting the body's homeostasis. The research reported here studies the rates of spontaneous hprt nmutationsand those induced you ggammairradiation in the splenocytes of mice at various ages. The rate of spontaneous and induced hprt gene mutations increases with aging. In gamma irradiated mice the rate of radiation-induced mutations depended on the absorbed dose and age, with the rate 2.3-3.0 fold higher in 104-110 week old mice than in younger pups. 15 refs., 1 tab

Adaptive synonymous mutations in an experimentally evolved Pseudomonas fluorescens population

DEFF Research Database (Denmark)

Bailey, Susan; Hinz, Aaron; Kassen, Rees

2014-01-01

Conventional wisdom holds that synonymous mutations, nucleotide changes that do not alter the encoded amino acid, have no detectable effect on phenotype or fitness. However, a growing body of evidence from both comparative and experimental studies suggests otherwise. Synonymous mutations have been...... shown to impact gene expression, protein folding and fitness, however, direct evidence that they can be positively selected, and so contribute to adaptation, is lacking. Here we report the recovery of two beneficial synonymous single base pair changes that arose spontaneously and independently...... in an experimentally evolved population of Pseudomonas fluorescens. We show experimentally that these mutations increase fitness by an amount comparable to non-synonymous mutations and that the fitness increases stem from increased gene expression. These results provide unequivocal evidence that synonymous mutations...

Revertant mutation releases confined lethal mutation, opening Pandora's box: a novel genetic pathogenesis.

Directory of Open Access Journals (Sweden)

Yasushi Ogawa

2014-05-01

Full Text Available When two mutations, one dominant pathogenic and the other "confining" nonsense, coexist in the same allele, theoretically, reversion of the latter may elicit a disease, like the opening of Pandora's box. However, cases of this hypothetical pathogenic mechanism have never been reported. We describe a lethal form of keratitis-ichthyosis-deafness (KID syndrome caused by the reversion of the GJB2 nonsense mutation p.Tyr136X that would otherwise have confined the effect of another dominant lethal mutation, p.Gly45Glu, in the same allele. The patient's mother had the identical misssense mutation which was confined by the nonsense mutation. The biological relationship between the parents and the child was confirmed by genotyping of 15 short tandem repeat loci. Haplotype analysis using 40 SNPs spanning the >39 kbp region surrounding the GJB2 gene and an extended SNP microarray analysis spanning 83,483 SNPs throughout chromosome 13 in the family showed that an allelic recombination event involving the maternal allele carrying the mutations generated the pathogenic allele unique to the patient, although the possibility of coincidental accumulation of spontaneous point mutations cannot be completely excluded. Previous reports and our mutation screening support that p.Gly45Glu is in complete linkage disequilibrium with p.Tyr136X in the Japanese population. Estimated from statisitics in the literature, there may be approximately 11,000 p.Gly45Glu carriers in the Japanese population who have this second-site confining mutation, which acts as natural genetic protection from the lethal disease. The reversion-triggered onset of the disesase shown in this study is a previously unreported genetic pathogenesis based on Mendelian inheritance.

Electrospray ionisation mass spectrometry facilitates detection of fibrinogen (Bbeta 14 Arg --> Cys) mutation in a family with thrombosis.

Science.gov (United States)

Brennan, S O; Hammonds, B; Spearing, R; George, P M

1997-12-01

We report the first direct detection of a fibrinogen mutation by electrospray ionisation mass spectrometry. The propositus, from a family with a history of thrombosis, came to attention after a pulmonary embolism subsequent to a spontaneous abortion. Prolonged thrombin (41 s) and reptilase times (26 s) together with an impairment of fibrinopeptide B release suggested a mutation at the thrombin cleavage site of the Bbeta chain. Direct mass analysis of purified fibrin chains from a thrombin induced clot showed that 50% of the Bbeta chains remained uncleaved. The measured mass of the mono sialo isoform of this uncleaved chain was 54150 Da, compared to a value of 54198 Da for normal Bbeta chains. This decrease of 48 Da in the intact protein is indicative of either a Bbeta 14 Arg to Cys, or Arg to Leu substitution. Heterozygosity for the Bbeta 14 Arg --> Cys mutation was verified by PCR amplification and DNA sequence analysis.

Missense mutation Lys18Asn in dystrophin that triggers X-linked dilated cardiomyopathy decreases protein stability, increases protein unfolding, and perturbs protein structure, but does not affect protein function.

Directory of Open Access Journals (Sweden)

Surinder M Singh

Full Text Available Genetic mutations in a vital muscle protein dystrophin trigger X-linked dilated cardiomyopathy (XLDCM. However, disease mechanisms at the fundamental protein level are not understood. Such molecular knowledge is essential for developing therapies for XLDCM. Our main objective is to understand the effect of disease-causing mutations on the structure and function of dystrophin. This study is on a missense mutation K18N. The K18N mutation occurs in the N-terminal actin binding domain (N-ABD. We created and expressed the wild-type (WT N-ABD and its K18N mutant, and purified to homogeneity. Reversible folding experiments demonstrated that both mutant and WT did not aggregate upon refolding. Mutation did not affect the protein's overall secondary structure, as indicated by no changes in circular dichroism of the protein. However, the mutant is thermodynamically less stable than the WT (denaturant melts, and unfolds faster than the WT (stopped-flow kinetics. Despite having global secondary structure similar to that of the WT, mutant showed significant local structural changes at many amino acids when compared with the WT (heteronuclear NMR experiments. These structural changes indicate that the effect of mutation is propagated over long distances in the protein structure. Contrary to these structural and stability changes, the mutant had no significant effect on the actin-binding function as evident from co-sedimentation and depolymerization assays. These results summarize that the K18N mutation decreases thermodynamic stability, accelerates unfolding, perturbs protein structure, but does not affect the function. Therefore, K18N is a stability defect rather than a functional defect. Decrease in stability and increase in unfolding decrease the net population of dystrophin molecules available for function, which might trigger XLDCM. Consistently, XLDCM patients have decreased levels of dystrophin in cardiac muscle.

Identification of Factors Interacting with hMSH2 and hMLH1 in the Fetal Liver and Investigations of how Mitochondrial Dysfunction Creates a Mutator Phenotype

DEFF Research Database (Denmark)

Rasmussen, Anne Karin

mutations. Mutations in MMR genes cause hereditary non-polyposis colon cancer. In an effort to identify unidentified genes involved in MMR and tissue-specific MMRassociated factors, we employed the yeast two-hybrid system, using the human hMSH2 as bait and a human fetal liver cDNA library as prey. We...... between mitochondrial activity and genomic instability. Mitochondrial dysfunction and genetic instability are characteristic features of cancer cells. Furthermore, mitochondrial dysfunction is a key feature of aging due to accumulation of mutations in mtDNA. Our studies in a yeast model system suggest......Increased spontaneous mutation frequency is associated with increased cancer risk. However, the relative contribution of spontaneous endogenous mutagenesis to carcinogenesis is not known today. Defects in the postreplication DNA mismatch repair (MMR) pathway are recognized to increase spontaneous...

Effects of mutagen-sensitive mus mutations on spontaneous mitotic recombination in Aspergillus.

Science.gov (United States)

Zhao, P; Kafer, E

1992-04-01

Methyl methane-sulfonate (MMS)-sensitive, radiation-induced mutants of Aspergillus were shown to define nine new DNA repair genes, musK to musS. To test mus mutations for effects on mitotic recombination, intergenic crossing over was assayed between color markers and their centromeres, and intragenic recombination between two distinguishable adE alleles. Of eight mutants analyzed, four showed significant deviations from mus+ controls in both tests. Two mutations, musK and musL, reduced recombination, while musN and musQ caused increases. In contrast, musO diploids produced significantly higher levels only for intragenic recombination. Effects were relatively small, but averages between hypo- and hyperrec mus differed 15-20-fold. In musL diploids, most of the rare color segregants resulted from mitotic malsegregation rather than intergenic crossing over. This indicates that the musL gene product is required for recombination and that DNA lesions lead to chromosome loss when it is deficient. In addition, analysis of the genotypes of intragenic (ad+) recombinants showed that the musL mutation specifically reduced single allele conversion but increased complex conversion types (especially recombinants homozygous for ad+). Similar analysis revealed differences between the effects of two hyperrec mutations; musN apparently caused high levels solely of mitotic crossing over, while musQ increased various conversion types but not reciprocal crossovers. These results suggest that mitotic gene conversion and crossing over, while generally associated, are affected differentially in some of the mus strains of Aspergillus nidulans.

Reversible Congenital Hypogonadotropic Hypogonadism in Patients with CHD7, FGFR1 or GNRHR Mutations

Science.gov (United States)

Laitinen, Eeva-Maria; Tommiska, Johanna; Sane, Timo; Vaaralahti, Kirsi; Toppari, Jorma; Raivio, Taneli

2012-01-01

Background Congenital hypogonadotropic hypogonadism (HH) is a rare cause for delayed or absent puberty. These patients may recover from HH spontaneously in adulthood. To date, it is not possible to predict who will undergo HH reversal later in life. Herein we investigated whether Finnish patients with reversal of congenital hypogonadotropic hypogonadism (HH) have common phenotypic or genotypic features. Methods and Findings Thirty-two male HH patients with anosmia/hyposmia (Kallmann Syndrome, KS; n = 26) or normal sense of smell (nHH; n = 6) were enrolled (age range, 18–61 yrs). The patients were clinically examined, and reversal of HH was assessed after treatment withdrawal. KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, WDR11, GNRHR, GNRH1, KISS1R, KISS1, TAC3, TACR3, and LHβ were screened for mutations. Six HH patients (2 KS, 4 nHH) were verified to have reversal of HH. In the majority of cases, reversal occurred early in adulthood (median age, 23 yrs; range, 21–39 yrs). All had spontaneous testicular growth while on testosterone replacement therapy (TRT). One nHH subject was restarted on TRT due to a decline in serum T. Two reversal variants had a same GNRHR mutation (R262Q), which was accompanied by another GNRHR mutation (R139H or del309F). In addition, both of the KS patients had a mutation in CHD7 (p.Q51X) or FGFR1 (c.91+2T>A). Conclusions Considerable proportion of patients with HH (8% of KS probands) may recover in early adulthood. Spontaneous testicular enlargement during TRT was highly suggestive for reversal of HH. Those with the GNRHR mutation R262Q accompanied by another GNRHR mutation may be prone to reversal, although even patients with a truncating mutation in CHD7 or a splice-site mutation in FGFR1 can recover. We recommend that all adolescents and young adults with congenital HH should be informed on the possibility of reversal. PMID:22724017

Reversible congenital hypogonadotropic hypogonadism in patients with CHD7, FGFR1 or GNRHR mutations.

Directory of Open Access Journals (Sweden)

Eeva-Maria Laitinen

Full Text Available BACKGROUND: Congenital hypogonadotropic hypogonadism (HH is a rare cause for delayed or absent puberty. These patients may recover from HH spontaneously in adulthood. To date, it is not possible to predict who will undergo HH reversal later in life. Herein we investigated whether Finnish patients with reversal of congenital hypogonadotropic hypogonadism (HH have common phenotypic or genotypic features. METHODS AND FINDINGS: Thirty-two male HH patients with anosmia/hyposmia (Kallmann Syndrome, KS; n = 26 or normal sense of smell (nHH; n = 6 were enrolled (age range, 18-61 yrs. The patients were clinically examined, and reversal of HH was assessed after treatment withdrawal. KAL1, FGFR1, FGF8, PROK2, PROKR2, CHD7, WDR11, GNRHR, GNRH1, KISS1R, KISS1, TAC3, TACR3, and LHβ were screened for mutations. Six HH patients (2 KS, 4 nHH were verified to have reversal of HH. In the majority of cases, reversal occurred early in adulthood (median age, 23 yrs; range, 21-39 yrs. All had spontaneous testicular growth while on testosterone replacement therapy (TRT. One nHH subject was restarted on TRT due to a decline in serum T. Two reversal variants had a same GNRHR mutation (R262Q, which was accompanied by another GNRHR mutation (R139H or del309F. In addition, both of the KS patients had a mutation in CHD7 (p.Q51X or FGFR1 (c.91+2T>A. CONCLUSIONS: Considerable proportion of patients with HH (8% of KS probands may recover in early adulthood. Spontaneous testicular enlargement during TRT was highly suggestive for reversal of HH. Those with the GNRHR mutation R262Q accompanied by another GNRHR mutation may be prone to reversal, although even patients with a truncating mutation in CHD7 or a splice-site mutation in FGFR1 can recover. We recommend that all adolescents and young adults with congenital HH should be informed on the possibility of reversal.

Induction of mutation and recombination following UV irradiation during meiosis in Saccharomyces cerevisiae

Energy Technology Data Exchange (ETDEWEB)

Kelly, S.L.; Parry, J.M. (University Coll. of Swansea (UK). Dept. of Genetics)

1983-03-01

Irradiation of yeast cultures with ultraviolet light at discrete stages during meiosis produces cyclic variations in sensitivity, i.e. cells are more sensitive to the lethal effects of UV light prior to entry into the meiotic DNA synthesis, and this corresponds to a peak of induction of point mutation. Cells become more resistant to both induced point mutation and lethality as they enter meiotic DNA synthesis, but become more sensitive again during spore formation. The induced level of intragenic recombination rises during the period of commitment ot recombination to a level indistinguishable from the full meiotic level of spontaneous intragenic recombination. Induced reciprocal recombination remains above the spontaneous level up to the point of commitment to sporulation.

A Case of Spontaneously Resolved Bilateral Primary Spontaneous Pneumothorax

Directory of Open Access Journals (Sweden)

Hasan Kahraman

2014-03-01

Full Text Available A condition of intrapleural air-space accumulation in individuals without any history of trauma or lung disease is called as primary spontaneous pneumothorax (PSP. Sixteen-years-old male patient admitted with complains of chest pain and dyspnea beginning 3 day ago. On physical examination, severity of breath sounds decreased on right side. Chest radiograph was taken and right-sided pneumothorax was detected and tube thoracostomy was inserted. Two months ago the patient referred to a doctor with similar complaints and physical examination and chest radiograph were reported as normal. The radiograph was retrospectively examined and bilateral PSP was detected. We presented the case duo to spontaneous recovery of bilateral PSP is seen very rarely and so contributes data to the literature. In patients admitted to the clinic with chest pain and shortness of breath, pneumothorax should be considered at differential diagnosis.

Spontaneous 8bp Deletion in Nbeal2 Recapitulates the Gray Platelet Syndrome in Mice

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Tomberg, Kärt; Khoriaty, Rami; Westrick, Randal J.; Fairfield, Heather E.; Reinholdt, Laura G.; Brodsky, Gary L.; Davizon-Castillo, Pavel; Ginsburg, David; Di Paola, Jorge

2016-01-01

During the analysis of a whole genome ENU mutagenesis screen for thrombosis modifiers, a spontaneous 8 base pair (bp) deletion causing a frameshift in exon 27 of the Nbeal2 gene was identified. Though initially considered as a plausible thrombosis modifier, this Nbeal2 mutation failed to suppress the synthetic lethal thrombosis on which the original ENU screen was based. Mutations in NBEAL2 cause Gray Platelet Syndrome (GPS), an autosomal recessive bleeding disorder characterized by macrothrombocytopenia and gray-appearing platelets due to lack of platelet alpha granules. Mice homozygous for the Nbeal2 8 bp deletion (Nbeal2gps/gps) exhibit a phenotype similar to human GPS, with significantly reduced platelet counts compared to littermate controls (p = 1.63 x 10−7). Nbeal2gps/gps mice also have markedly reduced numbers of platelet alpha granules and an increased level of emperipolesis, consistent with previously characterized mice carrying targeted Nbeal2 null alleles. These findings confirm previous reports, provide an additional mouse model for GPS, and highlight the potentially confounding effect of background spontaneous mutation events in well-characterized mouse strains. PMID:26950939

Spontaneous 8bp Deletion in Nbeal2 Recapitulates the Gray Platelet Syndrome in Mice.

Directory of Open Access Journals (Sweden)

Kärt Tomberg

Full Text Available During the analysis of a whole genome ENU mutagenesis screen for thrombosis modifiers, a spontaneous 8 base pair (bp deletion causing a frameshift in exon 27 of the Nbeal2 gene was identified. Though initially considered as a plausible thrombosis modifier, this Nbeal2 mutation failed to suppress the synthetic lethal thrombosis on which the original ENU screen was based. Mutations in NBEAL2 cause Gray Platelet Syndrome (GPS, an autosomal recessive bleeding disorder characterized by macrothrombocytopenia and gray-appearing platelets due to lack of platelet alpha granules. Mice homozygous for the Nbeal2 8 bp deletion (Nbeal2gps/gps exhibit a phenotype similar to human GPS, with significantly reduced platelet counts compared to littermate controls (p = 1.63 x 10-7. Nbeal2gps/gps mice also have markedly reduced numbers of platelet alpha granules and an increased level of emperipolesis, consistent with previously characterized mice carrying targeted Nbeal2 null alleles. These findings confirm previous reports, provide an additional mouse model for GPS, and highlight the potentially confounding effect of background spontaneous mutation events in well-characterized mouse strains.

[Dot1 and Set2 Histone Methylases Control the Spontaneous and UV-Induced Mutagenesis Levels in the Saccharomyces cerevisiae Yeasts].

Science.gov (United States)

Kozhina, T N; Evstiukhina, T A; Peshekhonov, V T; Chernenkov, A Yu; Korolev, V G

2016-03-01

In the Saccharomyces cerevisiae yeasts, the DOT1 gene product provides methylation of lysine 79 (K79) of hi- stone H3 and the SET2 gene product provides the methylation of lysine 36 (K36) of the same histone. We determined that the dot1 and set2 mutants suppress the UV-induced mutagenesis to an equally high degree. The dot1 mutation demonstrated statistically higher sensitivity to the low doses of MMC than the wild type strain. The analysis of the interaction between the dot1 and rad52 mutations revealed a considerable level of spontaneous cell death in the double dot1 rad52 mutant. We observed strong suppression of the gamma-in- duced mutagenesis in the set2 mutant. We determined that the dot1 and set2 mutations decrease the sponta- neous mutagenesis rate in both single and d ouble mutants. The epistatic interaction between the dot1 and set2 mutations and almost similar sensitivity of the corresponding mutants to the different types of DNA damage allow one to conclude that both genes are involved in the control of the same DNA repair pathways, the ho- mologous-recombination-based and the postreplicative DNA repair.

Selective Loss of Podoplanin Protein Expression Accompanies Proteinuria and Precedes Alterations in Podocyte Morphology in a Spontaneous Proteinuric Rat Model

Science.gov (United States)

Koop, Klaas; Eikmans, Michael; Wehland, Markus; Baelde, Hans; Ijpelaar, Daphne; Kreutz, Reinhold; Kawachi, Hiroshi; Kerjaschki, Dontscho; de Heer, Emile; Bruijn, Jan Anthonie

2008-01-01

To evaluate changes during the development of proteinuria, podocyte morphology and protein expression were evaluated in spontaneously proteinuric, Dahl salt-sensitive (Dahl SS) rats. Dahl SS rats on a low-salt diet were compared with spontaneously hypertensive rats (SHR) at age 2, 4, 6, 8, and 10 weeks. Blood pressure, urinary protein excretion, urinary albumin excretion, and podocyte morphology were evaluated. In addition, the expression of 11 podocyte-related proteins was determined by analyzing protein and mRNA levels. In Dahl SS rats, proteinuria became evident around week 5, increasing thereafter. SHR rats remained non-proteinuric. Dahl SS rats showed widespread foot process effacement at 10 weeks. At ≤8 weeks, expression and distribution of the podocyte proteins was similar between the two strains, except for the protein podoplanin. At 4 weeks, podoplanin began decreasing in the glomeruli of Dahl SS rats in a focal and segmental fashion. Podoplanin loss increased progressively and correlated with albuminuria (r = 0.8, P < 0.001). Double labeling experiments revealed increased expression of the podocyte stress marker desmin in glomerular areas where podoplanin was lost. Dahl SS rats did not show podoplanin gene mutations or decreased mRNA expression. Thus, podocyte morphology and the expression and distribution of most podocyte-specific proteins were normal in young Dahl SS rats, despite marked proteinuria. Our study suggests that decreased expression of podoplanin plays a role in the decrease of glomerular permselectivity. PMID:18599604

Mutation induction in Haemophilus influenzae by ICR-191. Pt. 1

International Nuclear Information System (INIS)

Perdue, S.W.; Kimball, R.F.; McGray, P.C.; Tennessee Univ., Oak Ridge

1981-01-01

The investigation of mutagenic mechanisms in Haemophilus influenzae has been confined until now to mutagens that normally produce mainly base pair substitutions. This paper describes the development of a system suitable for detecting frameshift mutations induced by ICR-191. The system involves reversions from thymidine dependence to thymidine independence. Evidence is presented from a comparison of the responses to ICR-191 and to N-methyl-N'-nitro-N-nitrosoguanidine that the system is specific for frameshift mutations. The genetic recombination involved in transformation leads to a marked increase in spontaneous reversion of the frameshift mutations but not of the base substitution mutations. Presumably, this is a consequence of mispairing, with consequent change in the number of bases, during the recombination. (orig.)

A spontaneous dominant-negative mutation within a 35S::AtMYB90 transgene inhibits flower pigment production in tobacco.

Science.gov (United States)

Velten, Jeff; Cakir, Cahid; Cazzonelli, Christopher I

2010-03-29

In part due to the ease of visual detection of phenotypic changes, anthocyanin pigment production has long been the target of genetic and molecular research in plants. Specific members of the large family of plant myb transcription factors have been found to play critical roles in regulating expression of anthocyanin biosynthetic genes and these genes continue to serve as important tools in dissecting the molecular mechanisms of plant gene regulation. A spontaneous mutation within the coding region of an Arabidopsis 35S::AtMYB90 transgene converted the activator of plant-wide anthocyanin production to a dominant-negative allele (PG-1) that inhibits normal pigment production within tobacco petals. Sequence analysis identified a single base change that created a premature nonsense codon, truncating the encoded myb protein. The resulting mutant protein lacks 78 amino acids from the wild type C-terminus and was confirmed as the source of the white-flower phenotype. A putative tobacco homolog of AtMYB90 (NtAN2) was isolated and found to be expressed in flower petals but not leaves of all tobacco plants tested. Using transgenic tobacco constitutively expressing the NtAN2 gene confirmed the NtAN2 protein as the likely target of PG-1-based inhibition of tobacco pigment production. Messenger RNA and anthocyanin analysis of PG-1Sh transgenic lines (and PG-1Sh x purple 35S::NtAN2 seedlings) support a model in which the mutant myb transgene product acts as a competitive inhibitor of the native tobacco NtAN2 protein. This finding is important to researchers in the field of plant transcription factor analysis, representing a potential outcome for experiments analyzing in vivo protein function in test transgenic systems that over-express or mutate plant transcription factors.

New mutations affecting induced mutagenesis in yeast.

Science.gov (United States)

Lawrence, C W; Krauss, B R; Christensen, R B

1985-01-01

Previously isolated mutations in baker's yeast, Saccharomyces cerevisiae, that impair induced mutagenesis were all identified with the aid of tests that either exclusively or predominantly detect base-pair substitutions. To avoid this bias, we have screened 11 366 potentially mutant clones for UV-induced reversion of the frameshift allele, his4-38, and have identified 10 mutants that give much reduced yields of revertants. Complementation and recombination tests show that 6 of these carry mutations at the previously known REV1, REV1 and REV3 loci, while the remaining 4 define 3 new genes, REV4 (2 mutations), REV5 and REV6. The rev4 mutations are readily suppressed in many genetic backgrounds and, like the rev5 mutation, impart only a limited deficiency for induced mutagenesis: it is likely, therefore that the REV4+ and REV5+ gene functions are only remotely concerned with this process. The rev6 mutants have a more general deficiency, however, as well as marked sensitivity to UV and an increased spontaneous mutation rate, properties that suggest the REV6 gene is directly involved in mutation induction. The REV5 gene is located about 1 cM proximal to CYC1 on chromosome X.

The induction of mutation and recombination following UV irradiation during meiosis in Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Kelly, S.L.; Parry, J.M.

1983-01-01

Irradiation of yeast cultures with ultraviolet light at discrete stages during meiosis produces cyclic variations in sensitivity, i.e. cells are more sensitive to the lethal effects of UV light prior to entry into the meiotic DNA synthesis, and this corresponds to a peak of induction of point mutation. Cells become more resistant to both induced point mutation and lethality as they enter meiotic DNA synthesis, but become more sensitive again during spore formation. The induced level of intragenic recombination rises during the period of commitment ot recombination to a level indistinguishable from the full meiotic level of spontaneous intragenic recombination. Induced reciprocal recombination remains above the spontaneous level up to the point of commitment to sporulation. (orig.)

The induction of mutation and recombination following UV irradiation during meiosis in Saccharomyces cerevisiae.

Science.gov (United States)

Kelly, S L; Parry, J M

1983-03-01

Irradiation of yeast cultures with ultraviolet light at discrete stages during meiosis produces cyclic variations in sensitivity, i.e. cells are more sensitive to the lethal effects of UV light prior to entry into the meiotic DNA synthesis, and this corresponds to a peak of induction of point mutation. Cells become more resistant to both induced point mutation and lethality as they enter meiotic DNA synthesis, but become more sensitive again during spore formation. The induced level of intragenic recombination rises during the period of commitment to recombination to a level indistinguishable from the full meiotic level of spontaneous intragenic recombination. Induced reciprocal recombination remains above the spontaneous level up to the point of commitment to sporulation.

A multiplex single nucleotide polymorphism typing assay for detecting mutations that result in decreased fluoroquinolone susceptibility in Salmonella enterica serovars Typhi and Paratyphi A.

LENUS (Irish Health Repository)

Song, Yajun

2010-08-01

OBJECTIVES: Decreased susceptibility to fluoroquinolones has become a major problem for the successful therapy of human infections caused by Salmonella enterica, especially the life-threatening typhoid and paratyphoid fevers. METHODS: By using Luminex xTAG beads, we developed a rapid, reliable and cost-effective multiplexed genotyping assay for simultaneously detecting 11 mutations in gyrA, gyrB and parE of S. enterica serovars Typhi and Paratyphi A that result in nalidixic acid resistance (Nal(R)) and\\/or decreased susceptibility to fluoroquinolones. RESULTS: This assay yielded unambiguous single nucleotide polymorphism calls on extracted DNA from 292 isolates of Salmonella Typhi (Nal(R) = 223 and Nal(S) = 69) and 106 isolates of Salmonella Paratyphi A (Nal(R) = 24 and Nal(S) = 82). All of the 247 Nal(R) Salmonella Typhi and Salmonella Paratyphi A isolates were found to harbour at least one of the target mutations, with GyrA Phe-83 as the most common one (143\\/223 for Salmonella Typhi and 18\\/24 for Salmonella Paratyphi A). We also identified three GyrB mutations in eight Nal(S) Salmonella Typhi isolates (six for GyrB Phe-464, one for GyrB Leu-465 and one for GyrB Asp-466), and mutations GyrB Phe-464 and GyrB Asp-466 seem to be related to the decreased ciprofloxacin susceptibility phenotype in Salmonella Typhi. This assay can also be used directly on boiled single colonies. CONCLUSIONS: The assay presented here would be useful for clinical and reference laboratories to rapidly screen quinolone-resistant isolates of Salmonella Typhi and Salmonella Paratyphi A, and decipher the underlying genetic changes for epidemiological purposes.

Inherited and environmentally induced differences in mutation frequencies between wild strains of Sordaria fimicola from "Evolution Canyon".

Science.gov (United States)

Lamb, B C; Saleem, M; Scott, W; Thapa, N; Nevo, E

1998-05-01

We have studied whether there is natural genetic variation for mutation frequencies, and whether any such variation is environment-related. Mutation frequencies differed significantly between wild strains of the fungus Sordaria fimicola isolated from a harsher or a milder microscale environment in "Evolution Canyon," Israel. Strains from the harsher, drier, south-facing slope had higher frequencies of new spontaneous mutations and of accumulated mutations than strains from the milder, lusher, north-facing slope. Collective total mutation frequencies over many loci for ascospore pigmentation were 2.3, 3.5 and 4.4% for three strains from the south-facing slope, and 0.9, 1.1, 1.2, 1.3 and 1.3% for five strains from the north-facing slope. Some of this between-slope difference was inherited through two generations of selfing, with average spontaneous mutation frequencies of 1.9% for south-facing slope strains and 0.8% for north-facing slope strains. The remainder was caused by different frequencies of mutations arising in the original environments. There was also significant heritable genetic variation in mutation frequencies within slopes. Similar between-slope differences were found for ascospore germination-resistance to acriflavine, with much higher frequencies in strains from the south-facing slope. Such inherited variation provides a basis for natural selection for optimum mutation rates in each environment.

Expanded simple tandem repeat (ESTR) mutation induction in the male germline: Lessons learned from lab mice

Energy Technology Data Exchange (ETDEWEB)

Somers, Christopher M. [University of Regina, Department of Biology, 3737 Wascana Parkway, Regina, SK, S4S 0A2 (Canada)]. E-mail: chris.somers@uregina.ca

2006-06-25

Expanded simple tandem repeat (ESTR) DNA loci that are unstable in the germline have provided the most sensitive tool ever developed for investigating low-dose heritable mutation induction in laboratory mice. Ionizing radiation exposures have shown that ESTR mutations occur mainly in pre-meiotic spermatogonia and stem cells. The average spermatogonial doubling dose is 0.62-0.69 Gy for low LET, and 0.18-0.34 Gy for high LET radiation. Chemical alkylating agents also cause significant ESTR mutation induction in pre-meiotic spermatogonia and stem cells, but are much less effective per unit dose than radiation. ESTR mutation induction efficiency is maximal at low doses of radiation or chemical mutagens, and may decrease at higher dose ranges. DNA repair deficient mice (SCID and PARP-1) with elevated levels of single and double-strand DNA breaks have spontaneously elevated ESTR mutation frequencies, and surprisingly do not show additional ESTR mutation induction following irradiation. In contrast, ESTR mutation induction in p53 knock-outs is indistinguishable from that of wild-type mice. Studies of sentinel mice exposed in situ to ambient air pollution showed elevated ESTR mutation frequencies in males exposed to high levels of particulate matter. These studies highlight the application of the ESTR assay for assessing environmental hazards under real-world conditions. All ESTR studies to date have shown untargeted mutations that occur at much higher frequencies than predicted. The mechanism of this untargeted mutation induction is unknown, and must be elucidated before we can fully understand the biological significance of ESTR mutations, or use these markers for formal risk assessment. Future studies should focus on the mechanism of ESTR mutation induction, refining dose responses, and developing ESTR markers for other animal species.

Expanded simple tandem repeat (ESTR) mutation induction in the male germline: Lessons learned from lab mice

International Nuclear Information System (INIS)

Somers, Christopher M.

2006-01-01

Expanded simple tandem repeat (ESTR) DNA loci that are unstable in the germline have provided the most sensitive tool ever developed for investigating low-dose heritable mutation induction in laboratory mice. Ionizing radiation exposures have shown that ESTR mutations occur mainly in pre-meiotic spermatogonia and stem cells. The average spermatogonial doubling dose is 0.62-0.69 Gy for low LET, and 0.18-0.34 Gy for high LET radiation. Chemical alkylating agents also cause significant ESTR mutation induction in pre-meiotic spermatogonia and stem cells, but are much less effective per unit dose than radiation. ESTR mutation induction efficiency is maximal at low doses of radiation or chemical mutagens, and may decrease at higher dose ranges. DNA repair deficient mice (SCID and PARP-1) with elevated levels of single and double-strand DNA breaks have spontaneously elevated ESTR mutation frequencies, and surprisingly do not show additional ESTR mutation induction following irradiation. In contrast, ESTR mutation induction in p53 knock-outs is indistinguishable from that of wild-type mice. Studies of sentinel mice exposed in situ to ambient air pollution showed elevated ESTR mutation frequencies in males exposed to high levels of particulate matter. These studies highlight the application of the ESTR assay for assessing environmental hazards under real-world conditions. All ESTR studies to date have shown untargeted mutations that occur at much higher frequencies than predicted. The mechanism of this untargeted mutation induction is unknown, and must be elucidated before we can fully understand the biological significance of ESTR mutations, or use these markers for formal risk assessment. Future studies should focus on the mechanism of ESTR mutation induction, refining dose responses, and developing ESTR markers for other animal species

Increase of the spontaneous mutation rate in a long-term experiment with Drosophila melanogaster.

Science.gov (United States)

Avila, Victoria; Chavarrías, David; Sánchez, Enrique; Manrique, Antonio; López-Fanjul, Carlos; García-Dorado, Aurora

2006-05-01

In a previous experiment, the effect of 255 generations of mutation accumulation (MA) on the second chromosome viability of Drosophila melanogaster was studied using 200 full-sib MA1 lines and a large C1 control, both derived from a genetically homogeneous base population. At generation 265, one of those MA1 lines was expanded to start 150 new full-sib MA2 lines and a new C2 large control. After 46 generations, the rate of decline in mean viability in MA2 was approximately 2.5 times that estimated in MA1, while the average degree of dominance of mutations was small and nonsignificant by generation 40 and moderate by generation 80. In parallel, the inbreeding depression rate for viability and the amount of additive variance for two bristle traits in C2 were 2-3 times larger than those in C1. The results are consistent with a mutation rate in the line from which MA2 and C2 were derived about 2.5 times larger than that in MA1. The mean viability of C2 remained roughly similar to that of C1, but the rate of MA2 line extinction increased progressively, leading to mutational collapse, which can be ascribed to accelerated mutation and/or synergy after important deleterious accumulation.

Recurrent PTPRB and PLCG1 mutations in angiosarcoma.

Science.gov (United States)

Behjati, Sam; Tarpey, Patrick S; Sheldon, Helen; Martincorena, Inigo; Van Loo, Peter; Gundem, Gunes; Wedge, David C; Ramakrishna, Manasa; Cooke, Susanna L; Pillay, Nischalan; Vollan, Hans Kristian M; Papaemmanuil, Elli; Koss, Hans; Bunney, Tom D; Hardy, Claire; Joseph, Olivia R; Martin, Sancha; Mudie, Laura; Butler, Adam; Teague, Jon W; Patil, Meena; Steers, Graham; Cao, Yu; Gumbs, Curtis; Ingram, Davis; Lazar, Alexander J; Little, Latasha; Mahadeshwar, Harshad; Protopopov, Alexei; Al Sannaa, Ghadah A; Seth, Sahil; Song, Xingzhi; Tang, Jiabin; Zhang, Jianhua; Ravi, Vinod; Torres, Keila E; Khatri, Bhavisha; Halai, Dina; Roxanis, Ioannis; Baumhoer, Daniel; Tirabosco, Roberto; Amary, M Fernanda; Boshoff, Chris; McDermott, Ultan; Katan, Matilda; Stratton, Michael R; Futreal, P Andrew; Flanagan, Adrienne M; Harris, Adrian; Campbell, Peter J

2014-04-01

Angiosarcoma is an aggressive malignancy that arises spontaneously or secondarily to ionizing radiation or chronic lymphoedema. Previous work has identified aberrant angiogenesis, including occasional somatic mutations in angiogenesis signaling genes, as a key driver of angiosarcoma. Here we employed whole-genome, whole-exome and targeted sequencing to study the somatic changes underpinning primary and secondary angiosarcoma. We identified recurrent mutations in two genes, PTPRB and PLCG1, which are intimately linked to angiogenesis. The endothelial phosphatase PTPRB, a negative regulator of vascular growth factor tyrosine kinases, harbored predominantly truncating mutations in 10 of 39 tumors (26%). PLCG1, a signal transducer of tyrosine kinases, encoded a recurrent, likely activating p.Arg707Gln missense variant in 3 of 34 cases (9%). Overall, 15 of 39 tumors (38%) harbored at least one driver mutation in angiogenesis signaling genes. Our findings inform and reinforce current therapeutic efforts to target angiogenesis signaling in angiosarcoma.

Induction of different types of mutations in yeast Saccharomyces serevisiae by γ-radiation

International Nuclear Information System (INIS)

Lyubimova, K.A.; Shvaneva, N.V.; Koltovaya, N.A.

2005-01-01

Several tester systems were used to study a wide spectrum of genetic changes induced by γ-radiation in the yeast Saccharomyces cerevisiae. The tester systems allow one to identify a loss of chromosomes, recombination (crossing over) and point mutations (frame shifts and base-pair substitutions.) Large genome changes were induced by γ-rays more efficiently than the point mutations. The dose dependence of the point mutations frequency was linear. Spontaneous and induced mutation rates per base pair corresponded with the known literature data for the same tester systems. Our finding shows that the used tester systems are not specific. They are useful for further study of mutations induced by ionizing radiation with various physical characteristics

Base substitution spectra of nalidixylate resistant mutations induced by monochromatic soft X and 60Co γ-rays in bacillus subtilis spores

International Nuclear Information System (INIS)

Takahashi, Nobuhiro; Hieda, Kotaro; Morohoshi, Fumiko; Munakata, Nobuo

1999-01-01

Bacillus subtilis spores were exposed to three types of photons, monochromatic soft X-rays with the energy corresponding to the absorption peak of phosphorus K-shell electron (2,153 eV) and with the slightly lower energy (2,147 eV), and 60 Co γ-rays. From the irradiated spores, 233 mutants exhibiting nalidixic acid resistance were isolated, and together with 94 spontaneous mutants, the sequence changes in the 5'-terminal region of the gyrA gene coding for DNA gyrase subunit A were determined. Among eighteen alleles of the gyrA mutations, eight were single-base substitutions, nine were tandem double-base substitutions, and one was a double substitution skipping a middle base pair. About 6% of the radiation-induced mutations were tandem double-base substitutions, whereas none was observed among the spontaneous ones. Among spontaneous mutations, A:T and G:C pairs were equally subjected to mutations, whereas the substitutions from G:C pairs and those to A:T pairs predominated among those induced with soft X-rays. The peak-energy X-rays were more effective in killing and causing mutations than the low-energy X-rays, however, there seemed no base-change events uniquely attributable to phosphorus K-shell absorption. (author)

Neonatal exposure to polybrominated diphenyl ether (PBDE 153) disrupts spontaneous behaviour, impairs learning and memory, and decreases hippocampal cholinergic receptors in adult mice

International Nuclear Information System (INIS)

Viberg, Henrik; Fredriksson, Anders; Eriksson, Per

2003-01-01

Neonatal exposure to polybrominated diphenyl ether (PBDE 153) disrupts spontaneous behaviour, impairs learning and memory, and decreases hippocampal cholinergic receptors in adult mice. Flame retardants are used to suppress or inhibit combustion processes in an effort to reduce the risk of fire. One class of flame retardants, polybrominated diphenyl ethers (PBDEs), are present and increasing in the environment and in human milk. The present study shows that neonatal exposure to 2,2',4,4',5,5'-hexaBDE (PBDE 153), a PBDE persistent both in environment and in human milk, can induce developmental neurotoxic effects, such as changes in spontaneous behaviour (hyperactivity), impairments in learning and memory, and reduced amounts of nicotinic receptors, effects that get worse with age. Neonatal NMRI male mice were orally exposed on day 10 to 0.45, 0.9, or 9.0 mg of PBDE 153/kg of body weight. Spontaneous behaviour (locomotion, rearing, and total activity) was observed in 2-, 4-, and 6-month-old mice, Morris water maze at an age of 6 months. The behaviour tests showed that the effects were dose-response and time-response related. Animals showing defects in learning and memory also showed significantly reduced amounts of nicotinic receptors in hippocampus, using α-bungarotoxin binding assay. The observed developmental neurotoxic effects seen for PBDE 153 are similar to those seen for PBDE 99 and for certain PCBs. Furthermore, PBDEs appear to as potent as the PCBs

Case of spontaneous ventriculocisternostomy

Energy Technology Data Exchange (ETDEWEB)

Yamane, Kanji; Yoshimoto, Hisanori; Harada, Kiyoshi; Uozumi, Tohru [Hiroshima Univ. (Japan). School of Medicine; Kuwabara, Satoshi

1983-05-01

The authors experienced a case of spontaneous ventriculocisternostomy diagnosed by CT scan with metrizamide and Conray. Patient was 23-year-old male who had been in good health until one month before admission, when he began to have headache and tinnitus. He noticed bilateral visual acuity was decreased about one week before admission and vomiting appeared two days before admission. He was admitted to our hospital because of bilateral papilledema and remarkable hydrocephalus diagnosed by CT scan. On admission, no abnormal neurological signs except for bilateral papilledema were noted. Immediately, right ventricular drainage was performed. Pressure of the ventricle was over 300mmH/sub 2/O and CSF was clear. PVG and PEG disclosed an another cavity behind the third ventricle, which was communicated with the third ventricle, and occlusion of aqueduct of Sylvius. Metrizamide CT scan and Conray CT scan showed a communication between this cavity and quadrigeminal and supracerebellar cisterns. On these neuroradiological findings, the diagnosis of obstructive hydrocephalus due to benign aqueduct stenosis accompanied with spontaneous ventriculocisternostomy was obtained. Spontaneous ventriculocisternostomy was noticed to produce arrest of hydrocephalus, but with our case, spontaneous regression of such symptoms did not appeared. By surgical ventriculocisternostomy (method by Torkildsen, Dandy, or Scarff), arrest of hydrocephalus was seen in about 50 to 70 per cent, which was the same results as those of spontaneous ventriculocisternostomy. It is concluded that VP shunt or VA shunt is thought to be better treatment of obstructive hydrocephalus than the various kinds of surgical ventriculocisternostomy.

MutS and MutL are dispensable for maintenance of the genomic mutation rate in the halophilic archaeon Halobacterium salinarum NRC-1.

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Courtney R Busch

Full Text Available BACKGROUND: The genome of the halophilic archaeon Halobacterium salinarum NRC-1 encodes for homologs of MutS and MutL, which are key proteins of a DNA mismatch repair pathway conserved in Bacteria and Eukarya. Mismatch repair is essential for retaining the fidelity of genetic information and defects in this pathway result in the deleterious accumulation of mutations and in hereditary diseases in humans. METHODOLOGY/PRINCIPAL FINDINGS: We calculated the spontaneous genomic mutation rate of H. salinarum NRC-1 using fluctuation tests targeting genes of the uracil monophosphate biosynthesis pathway. We found that H. salinarum NRC-1 has a low incidence of mutation suggesting the presence of active mechanisms to control spontaneous mutations during replication. The spectrum of mutational changes found in H. salinarum NRC-1, and in other archaea, appears to be unique to this domain of life and might be a consequence of their adaption to extreme environmental conditions. In-frame targeted gene deletions of H. salinarum NRC-1 mismatch repair genes and phenotypic characterization of the mutants demonstrated that the mutS and mutL genes are not required for maintenance of the observed mutation rate. CONCLUSIONS/SIGNIFICANCE: We established that H. salinarum NRC-1 mutS and mutL genes are redundant to an alternative system that limits spontaneous mutation in this organism. This finding leads to the puzzling question of what mechanism is responsible for maintenance of the low genomic mutation rates observed in the Archaea, which for the most part do not have MutS and MutL homologs.

Utilization of radiations in mutation breeding of tuber crops

International Nuclear Information System (INIS)

Kukimura, H.

1981-01-01

Most of the tuber crops are vegetatively propagated and their spontaneous mutations have been constructively utilized to practical farming. Significance of utilization of mutations to breeding should not be overlooked, since mutation can be articially induced by various mutagenic agents. In tuber crops, ionizing radiations are mostly applied to induce mutations. Radiosensitivity varies with species, genotypes and organs. For the purpose of mutation induction, 10-20 kR of gamma-rays is given to tubers and/or shoots in sweet potato and 2-10 kR in potato. It should be noted that radiation damage is more or less transmissible to later vegetative generations. A useful characters in practical agriculture, following mutations have been obtained so far: skin colour, short stemmed, changes in dry matter content, total sugars content and tuber yield, earlier maturity and sculf resistance in sweet potato. And, skin colour, changes in starch content and stolon length, day-neutral tuberization and cyst-nematode resistance in potato. Apart from mutations, radiation can be utilized for breaking down the incompatibility in sweet potato. Promising mutant clones with probable release in Japan are Kyushu 78 of sweet potato and Koniku 16 and Konkei 55 of potato. (author)

Spontaneous Pneumothorax in Birt-Hogg-Dube' Syndrome: Two Case Reports

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Bae, Hyoung Ju; Woo, Ok Hee; Yong, Hwan Seok; Kang, Eun Young; Kim, Hyun Koo; Choi, Young Ho; Shin, Bong Kyung; Kim, Yoon Kyung [Korea University School of Medicine, Korea University Guro Hospital, Seoul (Korea, Republic of)

2011-01-15

Birt-Hogg-Dube'(BHD) syndrome is a rare autosomal dominant inherited disorder that is characterized by skin fibrofolliculomas, renal tumors and multiple lung cysts with or without spontaneous pneumothorax. The disease is caused by germline mutations in the FLCN gene that codes for a protein of unknown function called folliculin. Patients with BHD syndrome do not always have all three manifestations of the skin, kidney and lung. To the best of our knowledge, there has been no case report of the radiologic findings of the lung manifestation in a patient with BHD syndrome in Korea. We report here on two cases of BHD syndrome that presented with spontaneous pneumothorax. The pulmonary abnormalities consisted of multiple thin-walled cysts of various sizes and shapes in both lungs

Reversible optic neuropathy with OPA1 exon 5b mutation

DEFF Research Database (Denmark)

Cornille, K.; Milea, D.; Amati-Bonneau, P.

2008-01-01

A new c.740G>A (R247H) mutation in OPA1 alternate spliced exon 5b was found in a patient presenting with bilateral optic neuropathy followed by partial, spontaneous visual recovery. R247H fibroblasts from the patient and his unaffected father presented unusual highly tubular mitochondrial network......, significant increased susceptibility to apoptosis, oxidative phosphorylation uncoupling, and altered OPA1 protein profile, supporting the pathogenicity of this mutation. These results suggest that the clinical spectrum of the OPA1-associated optic neuropathies may be larger than previously described...

Mutational analysis and genetic cloning of the agnostic locus, which regulates learning ability in Drosophila.

Science.gov (United States)

Peresleni, A I; Savvateeva, E V; Peresleni, I V; Sharagina, L M

1997-01-01

P-insertion mutations were obtained and localized by in situ methods at the agnostic gene (agn: 1-38.9; 11AB) in Drosophila. All agn mutants showed a wide spectrum of pleiotropic effects: an EMS-induced mutation of the agn-ts398 improved the ability to develop a conditioned defensive response and increased the activity of cAMP metabolic enzymes; spontaneous mutation of agnX1 showed morphological defects of the brain. P-insertion mutations were used to clone the gene; a restriction map of 80 kb in length was determined, and the insertion was localized to a fragment of 9 kb.

Decrease of Perivascular Adipose Tissue Browning Is Associated With Vascular Dysfunction in Spontaneous Hypertensive Rats During Aging

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Ling-Ran Kong

2018-04-01

Full Text Available Functional perivascular adipose tissue (PVAT is necessary to maintain vascular physiology through both mechanical support and endocrine or paracrine ways. PVAT shows a brown adipose tissue (BAT-like feature and the browning level of PVAT is dependent on the anatomic location and species. However, it is not clear whether PVAT browning is involved in the vascular tone regulation in spontaneously hypertensive rats (SHRs. In the present study, we aimed to illustrate the effect of aging on PVAT browning and subsequent vasomotor reaction in SHRs. Herein we utilized histological staining and western blot to detect the characteristics of thoracic PVAT (tPVAT in 8-week-old and 16-week-old SHR and Wistar-Kyoto (WKY rats. We also detected vascular reactivity analysis to determine the effect of tPVAT on vasomotor reaction during aging. The results showed that tPVAT had a similar phenotype to BAT, including smaller adipocyte size and positive uncoupling protein-1 (UCP1 staining. Interestingly, the tPVAT of 8-week-old SHR showed increased BAT phenotypic marker expression compared to WKY, whereas the browning level of tPVAT had a more dramatic decrease from 8 to 16 weeks of age in SHR than age-matched WKY rats. The vasodilation effect of tPVAT on aortas had no significant difference in 8-week-old WKY and SHR, whereas this effect is obviously decreased in 16-week-old SHR compared to WKY. In contrast, tPVAT showed a similar vasoconstriction effect in 8- or 16-week-old WKY and SHR rats. Moreover, we identified an important vasodilator adenosine, which regulates adipocyte browning and may be a potential PVAT-derived relaxing factor. Adenosine is dramatically decreased from 8 to 16 weeks of age in the tPVAT of SHR. In summary, aging is associated with a decrease of tPVAT browning and adenosine production in SHR rats. These may result in attenuated vasodilation effect of the tPVAT in SHR during aging.

Orofacial neuropathic pain reduces spontaneous burrowing behavior in rats.

Science.gov (United States)

Deseure, K; Hans, G

2018-07-01

It was recently reported that spontaneous burrowing behavior is decreased after tibial nerve transection, spinal nerve transection and partial sciatic nerve ligation. It was proposed that spontaneous burrowing could be used as a measure of the impact of neuropathic pain after peripheral nerve injury. It has remained unclear whether the reduction in burrowing behavior is caused directly by pain or hypersensitivity in the affected limbs, making it more difficult to perform burrowing, or by a pain induced decrease in the general wellbeing, thus reducing the motivation to burrow. We studied burrowing behavior after infraorbital nerve injury, a model of orofacial neuropathic pain that does not affect the limbs. Burrowing behavior was significantly reduced after infraorbital nerve injury. Isolated face grooming and responsiveness to mechanical von Frey stimulation of the infraorbital nerve territory were significantly increased after infraorbital nerve injury, indicative, respectively, of spontaneous pain and mechanical allodynia. It is concluded that spontaneous burrowing may provide a measure of the global impact of pain on the animal's wellbeing after peripheral nerve injury and incorporation of this behavioral assay in preclinical drug testing may improve the predictive validity of currently used pain models. Copyright © 2018 Elsevier Inc. All rights reserved.

THE THN MUTATION OF SCHIZOPHYLLUM-COMMUNE, WHICH SUPPRESSES FORMATION OF AERIAL HYPHAE, AFFECTS EXPRESSION OF THE SC3 HYDROPHOBIN GENE

NARCIS (Netherlands)

WESSELS, JGH; DEVRIES, OMH; ASGEIRSDOTTIR, SA; SPRINGER, J

1991-01-01

The spontaneous and recessive mutation thn in the basidiomycete Schizophyllum commune suppresses the formation of aerial hyphae in the monokaryon and, if present as a double dose, the formation of both aerial hyphae and fruit-bodies in the dikaryon. In the monokaryon, the mutation prevents

Suppressing cAMP response element-binding protein transcription shortens the duration of status epilepticus and decreases the number of spontaneous seizures in the pilocarpine model of epilepsy.

Science.gov (United States)

Zhu, Xinjian; Dubey, Deepti; Bermudez, Camilo; Porter, Brenda E

2015-12-01

Current epilepsy therapies directed at altering the function of neurotransmitter receptors or ion channels, or release of synaptic vesicles fail to prevent seizures in approximately 30% of patients. A better understanding of the molecular mechanism underlying epilepsy is needed to provide new therapeutic targets. The activity of cyclic AMP (cAMP) response element-binding protein (CREB), a major transcription factor promoting CRE-mediated transcription, increases following a prolonged seizure called status epilepticus. It is also increased in the seizure focus of patients with medically intractable focal epilepsy. Herein we explored the effect of acute suppression of CREB activity on status epilepticus and spontaneous seizures in a chronic epilepsy model. Pilocarpine chemoconvulsant was used to induce status epilepticus. To suppress CREB activity, a transgenic mouse line expressing an inducible dominant negative mutant of CREB (CREB(IR) ) with a serine to alanine 133 substitution was used. Status epilepticus and spontaneous seizures of transgenic and wild-type mice were analyzed using video-electroencephalography (EEG) to assess the effect of CREB suppression on seizures. Our findings indicate that activation of CREB(IR) shortens the duration of status epilepticus. The frequency of spontaneous seizures decreased in mice with chronic epilepsy during CREB(IR) induction; however, the duration of the spontaneous seizures was unchanged. Of interest, we found significantly reduced levels of phospho-CREB Ser133 upon activation of CREB(IR) , supporting prior work suggesting that binding to the CRE site is important for CREB phosphorylation. Our results suggest that CRE transcription supports seizure activity both during status epilepticus and in spontaneous seizures. Thus, blocking of CRE transcription is a novel target for the treatment of epilepsy. Wiley Periodicals, Inc. © 2015 International League Against Epilepsy.

Spontaneous cooperation for prosocials, but not for proselfs: Social value orientation moderates spontaneous cooperation behavior

Science.gov (United States)

Mischkowski, Dorothee; Glöckner, Andreas

2016-01-01

Cooperation is essential for the success of societies and there is an ongoing debate whether individuals have therefore developed a general spontaneous tendency to cooperate or not. Findings that cooperative behavior is related to shorter decision times provide support for the spontaneous cooperation effect, although contrary results have also been reported. We show that cooperative behavior is better described as person × situation interaction, in that there is a spontaneous cooperation effect for prosocial but not for proself persons. In three studies, one involving population representative samples from the US and Germany, we found that cooperation in a public good game is dependent on an interaction between individuals’ social value orientation and decision time. Increasing deliberation about the dilemma situation does not affect persons that are selfish to begin with, but it is related to decreasing cooperation for prosocial persons that gain positive utility from outcomes of others and score high on the related general personality trait honesty/humility. Our results demonstrate that the spontaneous cooperation hypothesis has to be qualified in that it is limited to persons with a specific personality and social values. Furthermore, they allow reconciling conflicting previous findings by identifying an important moderator for the effect. PMID:26876773

Mutator suppression and escape from replication error-induced extinction in yeast.

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Alan J Herr

2011-10-01

Full Text Available Cells rely on a network of conserved pathways to govern DNA replication fidelity. Loss of polymerase proofreading or mismatch repair elevates spontaneous mutation and facilitates cellular adaptation. However, double mutants are inviable, suggesting that extreme mutation rates exceed an error threshold. Here we combine alleles that affect DNA polymerase δ (Pol δ proofreading and mismatch repair to define the maximal error rate in haploid yeast and to characterize genetic suppressors of mutator phenotypes. We show that populations tolerate mutation rates 1,000-fold above wild-type levels but collapse when the rate exceeds 10⁻³ inactivating mutations per gene per cell division. Variants that escape this error-induced extinction (eex rapidly emerge from mutator clones. One-third of the escape mutants result from second-site changes in Pol δ that suppress the proofreading-deficient phenotype, while two-thirds are extragenic. The structural locations of the Pol δ changes suggest multiple antimutator mechanisms. Our studies reveal the transient nature of eukaryotic mutators and show that mutator phenotypes are readily suppressed by genetic adaptation. This has implications for the role of mutator phenotypes in cancer.

A case of spontaneous ventriculocisternostomy

International Nuclear Information System (INIS)

Yamane, Kanji; Yoshimoto, Hisanori; Harada, Kiyoshi; Uozumi, Tohru; Kuwabara, Satoshi.

1983-01-01

The authors experienced a case of spontaneous ventriculocisternostomy diagnosed by CT scan with metrizamide and Conray. Patient was 23-year-old male who had been in good health until one month before admission, when he began to have headache and tinnitus. He noticed bilateral visual acuity was decreased about one week before admission and vomiting appeared two days before admission. He was admitted to our hospital because of bilateral papilledema and remarkable hydrocephalus diagnosed by CT scan. On admission, no abnormal neurological signs except for bilateral papilledema were noted. Immediately, right ventricular drainage was performed. Pressure of the ventricle was over 300mmH 2 O and CSF was clear. PVG and PEG disclosed an another cavity behind the third ventricle, which was communicated with the third ventricle, and occlusion of aqueduct of Sylvius. Metrizamide CT scan and Conray CT scan showed a communication between this cavity and quadrigeminal and supracerebellar cisterns. On these neuroradiological findings, the diagnosis of obstructive hydrocephalus due to benign aqueduct stenosis accompanied with spontaneous ventriculocisternostomy was obtained. Spontaneous ventriculocisternostomy was noticed to produce arrest of hydrocephalus, but with our case, spontaneous regression of such symptoms did not appeared. By surgical ventriculocisternostomy (method by Torkildsen, Dandy, or Scarff), arrest of hydrocephalus was seen in about 50 to 70 per cent, which was the same results as those of spontaneous ventriculocisternostomy. It is concluded that VP shunt or VA shunt is thought to be better treatment of obstructive hydrocephalus than the various kinds of surgical ventriculocisternostomy. (J.P.N.)

SUMO E3 ligase Mms21 prevents spontaneous DNA damage induced genome rearrangements.

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Jason Liang

2018-03-01

Full Text Available Mms21, a subunit of the Smc5/6 complex, possesses an E3 ligase activity for the Small Ubiquitin-like MOdifier (SUMO. Here we show that the mms21-CH mutation, which inactivates Mms21 ligase activity, causes increased accumulation of gross chromosomal rearrangements (GCRs selected in the dGCR assay. These dGCRs are formed by non-allelic homologous recombination between divergent DNA sequences mediated by Rad52-, Rrm3- and Pol32-dependent break-induced replication. Combining mms21-CH with sgs1Δ caused a synergistic increase in GCRs rates, indicating the distinct roles of Mms21 and Sgs1 in suppressing GCRs. The mms21-CH mutation also caused increased rates of accumulating uGCRs mediated by breakpoints in unique sequences as revealed by whole genome sequencing. Consistent with the accumulation of endogenous DNA lesions, mms21-CH mutants accumulate increased levels of spontaneous Rad52 and Ddc2 foci and had a hyper-activated DNA damage checkpoint. Together, these findings support that Mms21 prevents the accumulation of spontaneous DNA lesions that cause diverse GCRs.

Mutation of Gly195 of the ChlH subunit of Mg-chelatase reduces chlorophyll and further disrupts PS II assembly in a Ycf48-deficient strain of Synechocystis sp. PCC 6803

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Tim Crawford

2016-07-01

Full Text Available Biogenesis of the photosystems in oxygenic phototrophs requires co-translational insertion of chlorophyll a. The first committed step of chlorophyll a biosynthesis is the insertion of a Mg2+ ion into the tetrapyrrole intermediate protoporphyrin IX, catalyzed by Mg-chelatase. We have identified a Synechocystis sp. PCC 6803 strain with a spontaneous mutation in chlH that results in a Gly195 to Glu substitution in a conserved region of the catalytic subunit of Mg-chelatase. Mutant strains containing the ChlH Gly195 to Glu mutation were generated using a two-step protocol that introduced the chlH gene into a putative neutral site in the chromosome prior to deletion of the native gene. The Gly195 to Glu mutation resulted in strains with decreased chlorophyll a. Deletion of the PS II assembly factor Ycf48 in a strain carrying the ChlH Gly195 to Glu mutation did not grow photoautotrophically. In addition, the ChlH-G195E:ΔYcf48 strain showed impaired PS II activity and decreased assembly of PS II centers in comparison to a ΔYcf48 strain. We suggest decreased chlorophyll in the ChlH-G195E mutant provides a background to screen for the role of assembly factors that are not essential under optimal growth conditions.

Germinal and somatic mutations in cancer

International Nuclear Information System (INIS)

Knudson, A.G. Jr.

1977-01-01

The role of germinal and somatic mutations in carcinogenesis leads to the conclusion that environmental carcinogens probably exert their effects via somatic mutations. Susceptibility to this process may itself be genetically determined, so we may deduce that two groups, one genetic and one non-genetic, are included in the 'environmental' class. Other individuals seem to acquire cancer even in the absence of such environmental agents, and these too may be classified into a genetic and a non-genetic group. It has been estimated that in industrial countries, the environmental groups include 70-80% of all cancer cases, but we are only beginning to know how to separate the genetic and non-genetic subgroups. The genetic subgroup of the 'non-environmental' group is very small, probably of the order of magnitude of 1-2% for cancer as a whole. The remainder, about 25%, comprises a non-genetic, non-environmental subgroup that seems to arise as a consequence of 'spontaneous' somatic mutations. The incidence of these 'background' cancers is what we should combat with preventive and therapeutic measures

Spontaneous regression of pulmonary bullae

International Nuclear Information System (INIS)

Satoh, H.; Ishikawa, H.; Ohtsuka, M.; Sekizawa, K.

2002-01-01

The natural history of pulmonary bullae is often characterized by gradual, progressive enlargement. Spontaneous regression of bullae is, however, very rare. We report a case in which complete resolution of pulmonary bullae in the left upper lung occurred spontaneously. The management of pulmonary bullae is occasionally made difficult because of gradual progressive enlargement associated with abnormal pulmonary function. Some patients have multiple bulla in both lungs and/or have a history of pulmonary emphysema. Others have a giant bulla without emphysematous change in the lungs. Our present case had treated lung cancer with no evidence of local recurrence. He had no emphysematous change in lung function test and had no complaints, although the high resolution CT scan shows evidence of underlying minimal changes of emphysema. Ortin and Gurney presented three cases of spontaneous reduction in size of bulla. Interestingly, one of them had a marked decrease in the size of a bulla in association with thickening of the wall of the bulla, which was observed in our patient. This case we describe is of interest, not only because of the rarity with which regression of pulmonary bulla has been reported in the literature, but also because of the spontaneous improvements in the radiological picture in the absence of overt infection or tumor. Copyright (2002) Blackwell Science Pty Ltd

Low Genetic Quality Alters Key Dimensions of the Mutational Spectrum.

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Nathaniel P Sharp

2016-03-01

Full Text Available Mutations affect individual health, population persistence, adaptation, diversification, and genome evolution. There is evidence that the mutation rate varies among genotypes, but the causes of this variation are poorly understood. Here, we link differences in genetic quality with variation in spontaneous mutation in a Drosophila mutation accumulation experiment. We find that chromosomes maintained in low-quality genetic backgrounds experience a higher rate of indel mutation and a lower rate of gene conversion in a manner consistent with condition-based differences in the mechanisms used to repair DNA double strand breaks. These aspects of the mutational spectrum were also associated with body mass, suggesting that the effect of genetic quality on DNA repair was mediated by overall condition, and providing a mechanistic explanation for the differences in mutational fitness decline among these genotypes. The rate and spectrum of substitutions was unaffected by genetic quality, but we find variation in the probability of substitutions and indels with respect to several aspects of local sequence context, particularly GC content, with implications for models of molecular evolution and genome scans for signs of selection. Our finding that the chances of mutation depend on genetic context and overall condition has important implications for how sequences evolve, the risk of extinction, and human health.

DNA mutation motifs in the genes associated with inherited diseases.

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Michal Růžička

Full Text Available Mutations in human genes can be responsible for inherited genetic disorders and cancer. Mutations can arise due to environmental factors or spontaneously. It has been shown that certain DNA sequences are more prone to mutate. These sites are termed hotspots and exhibit a higher mutation frequency than expected by chance. In contrast, DNA sequences with lower mutation frequencies than expected by chance are termed coldspots. Mutation hotspots are usually derived from a mutation spectrum, which reflects particular population where an effect of a common ancestor plays a role. To detect coldspots/hotspots unaffected by population bias, we analysed the presence of germline mutations obtained from HGMD database in the 5-nucleotide segments repeatedly occurring in genes associated with common inherited disorders, in particular, the PAH, LDLR, CFTR, F8, and F9 genes. Statistically significant sequences (mutational motifs rarely associated with mutations (coldspots and frequently associated with mutations (hotspots exhibited characteristic sequence patterns, e.g. coldspots contained purine tract while hotspots showed alternating purine-pyrimidine bases, often with the presence of CpG dinucleotide. Using molecular dynamics simulations and free energy calculations, we analysed the global bending properties of two selected coldspots and two hotspots with a G/T mismatch. We observed that the coldspots were inherently more flexible than the hotspots. We assume that this property might be critical for effective mismatch repair as DNA with a mutation recognized by MutSα protein is noticeably bent.

From molecular genetics to phylodynamics: evolutionary relevance of mutation rates across viruses.

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Rafael Sanjuán

Full Text Available Although evolution is a multifactorial process, theory posits that the speed of molecular evolution should be directly determined by the rate at which spontaneous mutations appear. To what extent these two biochemical and population-scale processes are related in nature, however, is largely unknown. Viruses are an ideal system for addressing this question because their evolution is fast enough to be observed in real time, and experimentally-determined mutation rates are abundant. This article provides statistically supported evidence that the mutation rate determines molecular evolution across all types of viruses. Properties of the viral genome such as its size and chemical composition are identified as major determinants of these rates. Furthermore, a quantitative analysis reveals that, as expected, evolution rates increase linearly with mutation rates for slowly mutating viruses. However, this relationship plateaus for fast mutating viruses. A model is proposed in which deleterious mutations impose an evolutionary speed limit and set an extinction threshold in nature. The model is consistent with data from replication kinetics, selection strength and chemical mutagenesis studies.

Screening for spontaneous virulent mutants of barley powdery mildew (Erysiphe graminis DC)

International Nuclear Information System (INIS)

Torp, J.; Jensen, H.P.

1989-01-01

Full text: Seedlings of 4 barley lines possessing resistance genes M1-a6, M1-a12 or M1-g were inoculated with powdery mildew culture CR3, which is a-virulent to the 4 host lines. In total, 50 million conidia were screened for the occurrence of virulent mutants, 43 putative virulent mutants were found. They could be grouped into 5 genotypes according to the virulence spectrum. They might have originated by one of the following events: 1. admixture, 2. physiological events that allow a few conidia to establish colonies in spite of the presence of a functional gene for resistance, 3. mutation in a gene for specificity, 4. deletion or mutation in some kind of suppressing element in which case more than one virulence may be affected. Based upon the virulence spectra, mating type, biochemical tests and analysis of test crosses, 3 of the genotypes were clearly classified as not being of mutational origin. Of the two remaining genotypes one differed in 4 virulences, the other by two virulences and one avirulence. Based upon expectations from the gene-for-gene concept, it is concluded that both were not of mutational origin. If in fact there are derived from a mutation, the concept of gene-for-gene interactions would have to be revised. Assuming that no mutations for virulence were found in this experiment, the spontaneous mutation frequency from avirulence to virulence would be below 2x10 -8 . (author)

Defect of Fe-S cluster binding by DNA polymerase δ in yeast suppresses UV-induced mutagenesis, but enhances DNA polymerase ζ - dependent spontaneous mutagenesis.

Science.gov (United States)

Stepchenkova, E I; Tarakhovskaya, E R; Siebler, H M; Pavlov, Y I

2017-01-01

Eukaryotic genomes are duplicated by a complex machinery, utilizing high fidelity replicative B-family DNA polymerases (pols) α, δ and ε. Specialized error-prone pol ζ, the fourth B-family member, is recruited when DNA synthesis by the accurate trio is impeded by replication stress or DNA damage. The damage tolerance mechanism dependent on pol ζ prevents DNA/genome instability and cell death at the expense of increased mutation rates. The pol switches occurring during this specialized replication are not fully understood. The loss of pol ζ results in the absence of induced mutagenesis and suppression of spontaneous mutagenesis. Disruption of the Fe-S cluster motif that abolish the interaction of the C-terminal domain (CTD) of the catalytic subunit of pol ζ with its accessory subunits, which are shared with pol δ, leads to a similar defect in induced mutagenesis. Intriguingly, the pol3-13 mutation that affects the Fe-S cluster in the CTD of the catalytic subunit of pol δ also leads to defective induced mutagenesis, suggesting the possibility that Fe-S clusters are essential for the pol switches during replication of damaged DNA. We confirmed that yeast strains with the pol3-13 mutation are UV-sensitive and defective in UV-induced mutagenesis. However, they have increased spontaneous mutation rates. We found that this increase is dependent on functional pol ζ. In the pol3-13 mutant strain with defective pol δ, there is a sharp increase in transversions and complex mutations, which require functional pol ζ, and an increase in the occurrence of large deletions, whose size is controlled by pol ζ. Therefore, the pol3-13 mutation abrogates pol ζ-dependent induced mutagenesis, but allows for pol ζ recruitment for the generation of spontaneous mutations and prevention of larger deletions. These results reveal differential control of the two major types of pol ζ-dependent mutagenesis by the Fe-S cluster present in replicative pol δ. Copyright © 2016

The influence of continuous γ-irradiation at decreasing dose-rate on the survival rote and induction of gene mutations in cultured Chinese hamster cells

International Nuclear Information System (INIS)

Feoktistova, T.P.; Elisova, E.V.; Stavrakova, N.M.

1991-01-01

Continuous γ-irradiation at decreasing dose-rate was shown to be less effective than acute exposure with regard to the lethal effect and frequency of mutations of resistance to 6-thioguanine in cultured Chinese hamster cells. The cell population subjected to continuons irradiation was d more radioresistant than the intact one. Lethal and genetic effects of continuous irradiation at decreasing dose-rate were mainly determined by the contribution of the radiation dose received during the first 24 h of exposure

Efffects of vigabatrin on spontaneous locomotor activity of rats

NARCIS (Netherlands)

Bouwman, B.M.; Rijn, C.M. van; Willems-van Bree, P.C.M.; Coenen, A.M.L.

2003-01-01

Effects of vigibatrin (saline, 125, 250, or 500 mg/kg i.p.) on spontaneous locomotor activity in Wistar rats were investigated. There was a dose dependent decrease in amount of locomotion for doses up to 250 mg/kg. This decrease was measurable 2-4 hours after injection and still became more

Altered spontaneous activity in anisometropic amblyopia subjects: revealed by resting-state FMRI.

Directory of Open Access Journals (Sweden)

Xiaoming Lin

Full Text Available Amblyopia, also known as lazy eye, usually occurs during early childhood and results in poor or blurred vision. Recent neuroimaging studies have found cortical structural/functional abnormalities in amblyopia. However, until now, it was still not known whether the spontaneous activity of the brain changes in amblyopia subjects. In the present study, regional homogeneity (ReHo, a measure of the homogeneity of functional magnetic resonance imaging signals, was used for the first time to investigate changes in resting-state local spontaneous brain activity in individuals with anisometropic amblyopia. Compared with age- and gender-matched subjects with normal vision, the anisometropic amblyopia subjects showed decreased ReHo of spontaneous brain activity in the right precuneus, the left medial prefrontal cortex, the left inferior frontal gyrus, and the left cerebellum, and increased ReHo of spontaneous brain activity was found in the bilateral conjunction area of the postcentral and precentral gyri, the left paracentral lobule, the left superior temporal gyrus, the left fusiform gyrus, the conjunction area of the right insula, putamen and the right middle occipital gyrus. The observed decreases in ReHo may reflect decreased visuo-motor processing ability, and the increases in ReHo in the somatosensory cortices, the motor areas and the auditory area may indicate compensatory plasticity in amblyopia.

Bibliography. Examples of literature related to the use of induced mutations in cross-breeding

International Nuclear Information System (INIS)

Micke, A.

1976-01-01

The bibliography contains about 400 references arranged alphabetically under the following 20 headings: Genetic analysis of mutants; Mutant gene combination and interaction; Pleiotropy versus linkage; Genetic background; Heterosis and overdominance; Mutations in heterozygous plants such as vegetatively propagated plants; Mutations in hybrids of self-pollinators; Distant hybridization; Increasing recombination; Alteration in the reproductive system; Alteration of photoperiodic response; Self and cross-incompatibility; Male or female sterility; Adaptability of mutants and mutant hybrids; Mutation induction in cross pollinators; Dwarfing mutant genes in cross-breeding; Protein mutants in cross-breeding; Disease resistant mutants in cross-breeding; Practical cross-breeding programmes using mutants; Spontaneous versus induced genetic diversity

Sigma virus and mutation in Drosophila melanogaster

International Nuclear Information System (INIS)

Paquin, S.L.A.

1977-01-01

- The objectives of these experiments have been (1) to verify and evidence more fully the action of sigma in causing recessive lethal mutation on the X chromosome of Drosophila, both in the male and the female germ line; (2) to extend the study of sigma-induced recessive lethal mutation to the Drosophila autosomes; (3) to explore the possibility that this mutagenesis is site-directed; (4) to study the effects of sigma virus in conjunction with radiation in increasing non-disjunction and dominant lethality. The virus increases the rate of radiation-induced nondisjunction by altering meiotic chromosomal behavior. Percentage of non-disjunction with 500 rads of x-rays in the virus-free flies was 0.176, while in sigma-containing lines it was 0.333. With high doses of either x or neutron radiation, the presence of the virus enhances the frequency of dominant lethality. The difference is especially significant with the fast neutrons. The results indicate that sigma, and presumably other viruses, are indeed environmental mutagens and are, therefore, factors in the rate of background or spontaneous mutation

A decrease in ubiquitination and resulting prolonged life-span of KIT underlies the KIT overexpression-mediated imatinib resistance of KIT mutation-driven canine mast cell tumor cells.

Science.gov (United States)

Kobayashi, Masato; Kuroki, Shiori; Kurita, Sena; Miyamoto, Ryo; Tani, Hiroyuki; Tamura, Kyoichi; Bonkobara, Makoto

2017-10-01

Overexpression of KIT is one of the mechanisms that contributes to imatinib resistance in KIT mutation-driven tumors. Here, the mechanism underlying this overexpression of KIT was investigated using an imatinib-sensitive canine mast cell tumor (MCT) line CoMS, which has an activating mutation in KIT exon 11. A KIT-overexpressing imatinib-resistant subline, rCoMS1, was generated from CoMS cells by their continuous exposure to increasing concentrations of imatinib. Neither a secondary mutation nor upregulated transcription of KIT was detected in rCoMS1 cells. A decrease in KIT ubiquitination, a prolonged KIT life-span, and KIT overexpression were found in rCoMS1 cells. These events were suppressed by withdrawal of imatinib and were re-induced by re‑treatment with imatinib. These findings suggest that imatinib elicited overexpression of KIT via suppression of its ubiquitination. These results also indicated that imatinib-induced overexpression of KIT in rCoMS1 cells was not a permanently acquired feature but was a reversible response of the cells. Moreover, the pan deubiquitinating enzyme inhibitor PR619 prevented imatinib induction of KIT overexpression, suggesting that the imatinib-induced decrease in KIT ubiquitination could be mediated by upregulation and/or activation of deubiquitinating enzyme(s). It may be possible that a similar mechanism of KIT overexpression underlies the acquisition of imatinib resistance in some human tumors that are driven by KIT mutation.

Elastatinal and leupeptin: effects on u.v.-induced mutation and sister-chromatid exchanges in Chinese hamster cells

International Nuclear Information System (INIS)

Paul, P.; Fujiwara, Y.

1981-01-01

Microbial protease inhibitors elastatinal and leupeptin were tested for cytotoxicity and for effects on spontaneous and u.v.-induced 6-thioguanine-resistant (6TGsup(r)) mutation and sister-chromatid exchange (SCE) in V79 Chinese hamster cells. Continuous treatment with elastatinal exhibited marked cytotoxicity, while leupeptin was almost non-cytotoxic. Elastatinal rapidly induced cytotoxic effects as a function of its concentration and time of exposure. Near maximum cytotoxicity was reached after exposures of 6-8 h and this was partially abolished by the presence of 2.5 μg cycloheximide per ml. Concentrations of either protease inhibitor which gave 60-80% survival had no appreciable effects on u.v. survival and frequencies of spontaneous and u.v.-induced 6TGsup(r) mutation and SCE. However, reconstruction experiments revealed that pretreatments of 6TGsup(r) and 6TGsup(s) (wild-type) cells with these inhibitors for 6 days tended to block metabolic co-operation in their co-cultures. Thus, elastatinal and leupeptin are neither clastogenic nor mutagenic by themselves, and do not alter mutation fixation and expression. (author)

Elastatinal and leupeptin: effects on u.v.-induced mutation and sister-chromatid exchanges in Chinese hamster cells

International Nuclear Information System (INIS)

Paul, P.; Fujiwara, Y.

1981-01-01

Microbial protease inhibitors elastatinal and leupeptin were tested for cytotoxicity and for effects on spontaneous and u.v.-induced 6-thioguanine-resistant (6TGr) mutation and sister-chromatid exchange (SCE) in V79 Chinese hamster cells. Continuous treatment with elastatinal exhibited marked cytotoxicity, while leupeptin was almost non-cytotoxic. Elastatinal rapidly induced cytotoxic effects as a function of its concentration and time of exposure. Near maximum cytotoxicity was reached after exposure of 6-8 h and this was partially abolished by the presence of 2.5 micrograms cycloheximide per ml. Concentrations of either protease inhibitor which gave 60-80% survival had no appreciable effects on u.v. survival and frequencies of spontaneous and u.v.-induced 6TGr mutation and SCE. However, reconstruction experiments revealed that pretreatments of 6TGr and 6TGs (wild-type) cells with these inhibitors for 6 days tended to block metabolic co-operation in their co-cultures. Thus, elastatinal and leupeptin are neither clastogenic mutagenic by themselves, and do not alter mutation fixation and expression

Splicing mutation in Sbf1 causes nonsyndromic male infertility in the rat

Czech Academy of Sciences Publication Activity Database

Liška, F.; Chylíková, B.; Janků, M.; Šeda, Ondřej; Vernerová, Z.; Pravenec, Michal; Křen, Vladimír

2016-01-01

Roč. 152, č. 3 (2016), s. 215-223 ISSN 1470-1626 R&D Projects: GA CR(CZ) GA16-06548S Institutional support: RVO:67985823 ; RVO:68378050 Keywords : Sbf1 (SET binding factor 1) gene mutation * male infertility * spontaneously hypertensive rat Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.100, year: 2016

In vitro mutation induction for resistance to Fusarium wilt in the banana

Energy Technology Data Exchange (ETDEWEB)

Tulmann Neto, A; Mendes, B M.J.; Latado, R [Centro de Energia Nuclear na Agricultura, Piracicaba, SP (Brazil); Cesar Santos, P dos; Boliani, A [Universidade Estadual Paulista, Ilha Solteira, SP (Brazil). Faculdade de Agronomia

1995-11-01

In Brazil, which is one of the world`s principal banana production regions, almost all production is consumed within the country. Consumers show high preference for the cultivar Maca (AAB group). However, it is becoming increasingly difficult to produce bananas of this type because of their high susceptibility to Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense. Sexual breeding, which consists of recombination and selection, is limited in the banana because of polyploidy and sterility. Spontaneous somatic mutations are an important source of new cultirvars, and mutation breeding might be particularly important to generate genetic variation. Because of this, the mutation breeding approach has been used in Brazil. The objective of this research was to induce gamma ray mutations for resistance or to increase the level of tolerance to Fusarium wilt in the banana cultivar Maca on the basis of screening under field conditions. 4 refs.

Constitutional SAMD9L mutations cause familial myelodysplastic syndrome and transient monosomy 7.

Science.gov (United States)

Pastor, Victor B; Sahoo, Sushree S; Boklan, Jessica; Schwabe, Georg C; Saribeyoglu, Ebru; Strahm, Brigitte; Lebrecht, Dirk; Voss, Matthias; Bryceson, Yenan T; Erlacher, Miriam; Ehninger, Gerhard; Niewisch, Marena; Schlegelberger, Brigitte; Baumann, Irith; Achermann, John C; Shimamura, Akiko; Hochrein, Jochen; Tedgård, Ulf; Nilsson, Lars; Hasle, Henrik; Boerries, Melanie; Busch, Hauke; Niemeyer, Charlotte M; Wlodarski, Marcin W

2018-03-01

Familial myelodysplastic syndromes arise from haploinsufficiency of genes involved in hematopoiesis and are primarily associated with early-onset disease. Here we describe a familial syndrome in seven patients from four unrelated pedigrees presenting with myelodysplastic syndrome and loss of chromosome 7/7q. Their median age at diagnosis was 2.1 years (range, 1-42). All patients presented with thrombocytopenia with or without additional cytopenias and a hypocellular marrow without an increase of blasts. Genomic studies identified constitutional mutations (p.H880Q, p.R986H, p.R986C and p.V1512M) in the SAMD9L gene on 7q21, with decreased allele frequency in hematopoiesis. The non-random loss of mutated SAMD9L alleles was attained via monosomy 7, deletion 7q, UPD7q, or acquired truncating SAMD9L variants p.R1188X and p.S1317RfsX21. Incomplete penetrance was noted in 30% (3/10) of mutation carriers. Long-term observation revealed divergent outcomes with either progression to leukemia and/or accumulation of driver mutations (n=2), persistent monosomy 7 (n=4), and transient monosomy 7 followed by spontaneous recovery with SAMD9L -wildtype UPD7q (n=2). Dysmorphic features or neurological symptoms were absent in our patients, pointing to the notion that myelodysplasia with monosomy 7 can be a sole manifestation of SAMD9L disease. Collectively, our results define a new subtype of familial myelodysplastic syndrome and provide an explanation for the phenomenon of transient monosomy 7. Registered at: www.clinicaltrials.gov; #NCT00047268 . Copyright© 2018 Ferrata Storti Foundation.

Decreased spontaneous attention to social scenes in 6-month-old infants later diagnosed with autism spectrum disorders.

Science.gov (United States)

Chawarska, Katarzyna; Macari, Suzanne; Shic, Frederick

2013-08-01

The ability to spontaneously attend to the social overtures and activities of others is essential for the development of social cognition and communication. This ability is critically impaired in toddlers with autism spectrum disorders (ASD); however, it is not clear if prodromal symptoms in this area are already present in the first year of life of those affected by the disorder. To examine whether 6-month-old infants later diagnosed with ASD exhibit atypical spontaneous social monitoring skills, visual responses of 67 infants at high-risk and 50 at low-risk for ASD were studied using an eye-tracking task. Based on their clinical presentation in the third year, infants were divided into those with ASD, those exhibiting atypical development, and those developing typically. Compared with the control groups, 6-month-old infants later diagnosed with ASD attended less to the social scene, and when they did look at the scene, they spent less time monitoring the actress in general and her face in particular. Limited attention to the actress and her activities was not accompanied by enhanced attention to objects. Prodromal symptoms of ASD at 6 months include a diminished ability to attend spontaneously to people and their activities. A limited attentional bias toward people early in development is likely to have a detrimental impact on the specialization of social brain networks and the emergence of social interaction patterns. Further investigation into its underlying mechanisms and role in psychopathology of ASD in the first year is warranted. Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

PPIB mutations cause severe osteogenesis imperfecta.

Science.gov (United States)

van Dijk, Fleur S; Nesbitt, Isabel M; Zwikstra, Eline H; Nikkels, Peter G J; Piersma, Sander R; Fratantoni, Silvina A; Jimenez, Connie R; Huizer, Margriet; Morsman, Alice C; Cobben, Jan M; van Roij, Mirjam H H; Elting, Mariet W; Verbeke, Jonathan I M L; Wijnaendts, Liliane C D; Shaw, Nick J; Högler, Wolfgang; McKeown, Carole; Sistermans, Erik A; Dalton, Ann; Meijers-Heijboer, Hanne; Pals, Gerard

2009-10-01

Deficiency of cartilage-associated protein (CRTAP) or prolyl 3-hydroxylase 1(P3H1) has been reported in autosomal-recessive lethal or severe osteogenesis imperfecta (OI). CRTAP, P3H1, and cyclophilin B (CyPB) form an intracellular collagen-modifying complex that 3-hydroxylates proline at position 986 (P986) in the alpha1 chains of collagen type I. This 3-prolyl hydroxylation is decreased in patients with CRTAP and P3H1 deficiency. It was suspected that mutations in the PPIB gene encoding CyPB would also cause OI with decreased collagen 3-prolyl hydroxylation. To our knowledge we present the first two families with recessive OI caused by PPIB gene mutations. The clinical phenotype is compatible with OI Sillence type II-B/III as seen with COL1A1/2, CRTAP, and LEPRE1 mutations. The percentage of 3-hydroxylated P986 residues in patients with PPIB mutations is decreased in comparison to normal, but it is higher than in patients with CRTAP and LEPRE1 mutations. This result and the fact that CyPB is demonstrable independent of CRTAP and P3H1, along with reported decreased 3-prolyl hydroxylation due to deficiency of CRTAP lacking the catalytic hydroxylation domain and the known function of CyPB as a cis-trans isomerase, suggest that recessive OI is caused by a dysfunctional P3H1/CRTAP/CyPB complex rather than by the lack of 3-prolyl hydroxylation of a single proline residue in the alpha1 chains of collagen type I.

Impaired action potential initiation in GABAergic interneurons causes hyperexcitable networks in an epileptic mouse model carrying a human Na(V)1.1 mutation.

Science.gov (United States)

Hedrich, Ulrike B S; Liautard, Camille; Kirschenbaum, Daniel; Pofahl, Martin; Lavigne, Jennifer; Liu, Yuanyuan; Theiss, Stephan; Slotta, Johannes; Escayg, Andrew; Dihné, Marcel; Beck, Heinz; Mantegazza, Massimo; Lerche, Holger

2014-11-05

Mutations in SCN1A and other ion channel genes can cause different epileptic phenotypes, but the precise mechanisms underlying the development of hyperexcitable networks are largely unknown. Here, we present a multisystem analysis of an SCN1A mouse model carrying the NaV1.1-R1648H mutation, which causes febrile seizures and epilepsy in humans. We found a ubiquitous hypoexcitability of interneurons in thalamus, cortex, and hippocampus, without detectable changes in excitatory neurons. Interestingly, somatic Na(+) channels in interneurons and persistent Na(+) currents were not significantly changed. Instead, the key mechanism of interneuron dysfunction was a deficit of action potential initiation at the axon initial segment that was identified by analyzing action potential firing. This deficit increased with the duration of firing periods, suggesting that increased slow inactivation, as recorded for recombinant mutated channels, could play an important role. The deficit in interneuron firing caused reduced action potential-driven inhibition of excitatory neurons as revealed by less frequent spontaneous but not miniature IPSCs. Multiple approaches indicated increased spontaneous thalamocortical and hippocampal network activity in mutant mice, as follows: (1) more synchronous and higher-frequency firing was recorded in primary neuronal cultures plated on multielectrode arrays; (2) thalamocortical slices examined by field potential recordings revealed spontaneous activities and pathological high-frequency oscillations; and (3) multineuron Ca(2+) imaging in hippocampal slices showed increased spontaneous neuronal activity. Thus, an interneuron-specific generalized defect in action potential initiation causes multisystem disinhibition and network hyperexcitability, which can well explain the occurrence of seizures in the studied mouse model and in patients carrying this mutation. Copyright © 2014 the authors 0270-6474/14/3414874-16$15.00/0.

Matrilin-3 Chondrodysplasia Mutations Cause Attenuated Chondrogenesis, Premature Hypertrophy and Aberrant Response to TGF-β in Chondroprogenitor Cells

OpenAIRE

Chathuraka T. Jayasuriya; Fiona H. Zhou; Ming Pei; Zhengke Wang; Nicholas J. Lemme; Paul Haines; Qian Chen

2014-01-01

Studies have shown that mutations in the matrilin-3 gene (MATN3) are associated with multiple epiphyseal dysplasia (MED) and spondyloepimetaphyseal dysplasia (SEMD). We tested whether MATN3 mutations affect the differentiation of chondroprogenitor and/or mesenchymal stem cells, which are precursors to chondrocytes. ATDC5 chondroprogenitors stably expressing wild-type (WT) MATN3 underwent spontaneous chondrogenesis. Expression of chondrogenic markers collagen II and aggrecan was inhibited in c...

[The role of remodeling complexes CHD1 and ISWI in spontaneous and UV-induced mutagenesis control in yeast Saccharomyces cerevisiae].

Science.gov (United States)

Evstiukhina, T A; Alekseeva, E A; Fedorov, D V; Peshekhonov, V T; Korolev, V G

2017-02-01

Chromatin remodulators are special multiprotein machines capable of transforming the structure, constitution, and positioning of nucleosomes on DNA. Biochemical activities of remodeling complexes CHD1 and ISWI from the SWI2/SNF2 family are well established. They ensure correct positioning of nucleosomes along the genome, which is probably critical for genome stability, in particular, after action of polymerases, repair enzymes, and transcription. In this paper, we show that single mutations in genes ISW1, ISW2, and CHD1 weakly affect repair and mutagenic processes in yeast cells. At the same time, there are differences in the effect of these mutations on spontaneous mutation levels, which indicates certain specificity of action of protein complexes ISW1, ISW2, and CHD1 on expression of different genes that control repair and mutation processes in yeast.

Identification of potential molecular markers of ionizing radiation-induced mutations at the hprt locus in CHO cells

International Nuclear Information System (INIS)

Schwartz, J.L.; Sun, J.; Porter, R.C.

1995-01-01

Using multiplex polymerase chain reaction-based exon deletion analysis, we have analyzed mutations at the hprt locus from independent CHO cell mutants isolated from untreated, 60 Co x-ray-, and 212 Bi-exposed CHO-K1 cello and its radiation-sensitive derivative, xrs-5. In the 71 spontaneous CHO-K1 mutants analyzed, 78% showed no change in exon number or size, 20% showed loss of 1-8 exons (partial deletion), and 3% showed loss of all nine hprt exons (total deletion). Exposure of CHO-K1 cells to 6 Gy of γ rays (10% survival) produced 45% of the 20 mutants analyzed showing partial deletion, and 30% showing total deletion. Exposure to an equitoxic dose of a radiation from 212 Bi, a 220 Rn daughter, resulted in a spectrum similar to the γ-ray spectrum in that more than 75% of the 49 mutants analyzed were deletions. The α-radiation, however, tended to produce larger intragenic deletions that γ radiation. Of the 87 spontaneous xrs-5 mutants analyzed for deletions 44% showed partial deletion, and 14% showed total deletion. Exposure to α radiation (10% survival) resulted in a deletion spectrum similar to that seen in CHO-K1 cells. Of the 49 mutants analyzed, 43% showed no change in exon number or size, 16% showed partial deletion, and 41% showed total deletion. While the defect in xrs-5 has a profound effect on spontaneous mutation spectra, it does not appear to affect α-induced mutation spectra

Retrospective genetic study of germinative mutations in Str loci of individuals potentially exposed to ionizing radiation

International Nuclear Information System (INIS)

Costa, Emilia Oliveira Alves

2010-01-01

The Brazilian radiological accident that occurred in 1987, in Goiania, it was a terrible radiation episode. As a consequence, hundreds of people were contaminated due to the Cesium-137 radiation. Recently, many studies had shown that genome instabilities, such as, mutations, chromosomal aberrations, micronuclei formation and micro satellite instability and a delay on cellular death are usually reported on mammal cells exposed to ionizing radiation, being considered as a manly risk to humans. Mutations can be spontaneous, and the occurrence is dependent on the organism, or, induced, being associated to mutagenic exposition. Ionizing radiations are an example of physical and mutagenic agents that could harm the cell repair and could cause the development of many types of cancer. The evaluation of the biological effects of the ionizing radiation, in somatic and germ line cells, with a consequent determination of the radio-induced mutations, it is extremely important to estimate the genetic risks, manly in population exposed to radiation. The analyses of repetitive DNA sequences have been demonstrated that such sequences are prone to high rates of spontaneous mutations. The minisatellites and microsatellites have been used to demonstrate the induction of germ line mutation rates on mouse, humans, among others organisms. The aim of the present study was to analyze the frequency of microsatellite alterations to determine the mutation rates occurred in germ cells of the parents exposed to the ionizing radiation of the Cesium-137. The studied group was constitute of 10 families of individuals accidentally exposed to Cesium-137 and by the control group constituted by 645 healthy individuals who carried out paternity tests on 2009. We found only one mutation of paternal origin in the D8S1179 locus on the exposed group, being the mutation rate of 0.002. In the control group, we found 01 mutation on D16S539 loei and on D3S1358; 02 mutations on Penta E loeus; 04 mutations on D

Does Spontaneous Favorability to Power (vs. Universalism) Values Predict Spontaneous Prejudice and Discrimination?

Science.gov (United States)

Souchon, Nicolas; Maio, Gregory R; Hanel, Paul H P; Bardin, Brigitte

2017-10-01

We conducted five studies testing whether an implicit measure of favorability toward power over universalism values predicts spontaneous prejudice and discrimination. Studies 1 (N = 192) and 2 (N = 86) examined correlations between spontaneous favorability toward power (vs. universalism) values, achievement (vs. benevolence) values, and a spontaneous measure of prejudice toward ethnic minorities. Study 3 (N = 159) tested whether conditioning participants to associate power values with positive adjectives and universalism values with negative adjectives (or inversely) affects spontaneous prejudice. Study 4 (N = 95) tested whether decision bias toward female handball players could be predicted by spontaneous attitude toward power (vs. universalism) values. Study 5 (N = 123) examined correlations between spontaneous attitude toward power (vs. universalism) values, spontaneous importance toward power (vs. universalism) values, and spontaneous prejudice toward Black African people. Spontaneous positivity toward power (vs. universalism) values was associated with spontaneous negativity toward minorities and predicted gender bias in a decision task, whereas the explicit measures did not. These results indicate that the implicit assessment of evaluative responses attached to human values helps to model value-attitude-behavior relations. © 2016 The Authors. Journal of Personality Published by Wiley Periodicals, Inc.

A dominant-negative mutation within AtMYB90 blocks flower pigment production in transgenic tobacco.

Science.gov (United States)

During de novo shoot induction in cultured transgenic tobacco callus a spontaneous mutation within the coding region of a AtMYB90 transgene produced a plant line in which the original transgene-induced over-pigmented phenotype (dark red/purple from anthocyanin overproduction in most tissues) was los...

Further evidence for elevated human minisatellite mutation rate in Belarus eight years after the Chernobyl accident

International Nuclear Information System (INIS)

Dubrova, Yuri E.; Buard, Jerome; Jeffreys, Alec J.; Nesterov, Valeri N.; Krouchinsky, Nicolay G.; Ostapenko, Vladislav A.; Vergnaud, Gilles; Giraudeau, Fabienne

1997-01-01

Analysis of germline mutation rate at human minisatellites among children born in areas of the Mogilev district of Belarus heavily polluted after the Chernobyl accident has been extended, both by recruiting more families from the affected region and by using five additional minisatellite probes, including multi-locus probe 33.6 and four hypervariable single-locus probes. These additional data confirmed a twofold higher mutation rate in exposed families compared with non-irradiated families from the United Kingdom. An elevated rate was seen at all three independent sets of minisatellites (detected separately by multi-locus probes 33.15, 33.6 and six single-locus probes), indicating a generalised increase in minisatellite germline mutation rate in the Belarus families. Within the Belarus cohort, mutation rate was significantly greater in families with higher parental radiation dose estimated for chronic external and internal exposure to caesium-137, consistent with radiation induction of germline mutation. The spectra of mutation seen in the unexposed and exposed families were indistinguishable, suggesting that increased mutation observed over multiple loci arises indirectly by some mechanism that enhances spontaneous minisatellite mutation

Spontaneous Loss of Virulence in Natural Populations of Listeria monocytogenes.

Science.gov (United States)

Maury, Mylène M; Chenal-Francisque, Viviane; Bracq-Dieye, Hélène; Han, Lei; Leclercq, Alexandre; Vales, Guillaume; Moura, Alexandra; Gouin, Edith; Scortti, Mariela; Disson, Olivier; Vázquez-Boland, José A; Lecuit, Marc

2017-11-01

The pathogenesis of Listeria monocytogenes depends on the ability of this bacterium to escape from the phagosome of the host cells via the action of the pore-forming toxin listeriolysin O (LLO). Expression of the LLO-encoding gene ( hly ) requires the transcriptional activator PrfA, and both hly and prfA genes are essential for L. monocytogenes virulence. Here, we used the hemolytic activity of LLO as a phenotypic marker to screen for spontaneous virulence-attenuating mutations in L. monocytogenes Sixty nonhemolytic isolates were identified among a collection of 57,820 confirmed L. monocytogenes strains isolated from a variety of sources (0.1%). In most cases (56/60; 93.3%), the nonhemolytic phenotype resulted from nonsense, missense, or frameshift mutations in prfA Five strains carried hly mutations leading to a single amino acid substitution (G299V) or a premature stop codon causing strong virulence attenuation in mice. In one strain, both hly and gshF (encoding a glutathione synthase required for full PrfA activity) were missing due to genomic rearrangements likely caused by a transposable element. The PrfA/LLO loss-of-function (PrfA - /LLO - ) mutants belonged to phylogenetically diverse clades of L. monocytogenes , and most were identified among nonclinical strains (57/60). Consistent with the rare occurrence of loss-of-virulence mutations, we show that prfA and hly are under purifying selection. Although occurring at a low frequency, PrfA - /LLO - mutational events in L. monocytogenes lead to niche restriction and open an evolutionary path for obligate saprophytism in this facultative intracellular pathogen. Copyright © 2017 Maury et al.

Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1

DEFF Research Database (Denmark)

Goudie, David R; D'Alessandro, Mariella; Merriman, Barry

2011-01-01

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith disease (FSD), is an autosomal-dominant skin cancer condition characterized by multiple squamous-carcinoma-like locally invasive skin tumors that grow rapidly for a few weeks before spontaneously regressing, leaving s......-of-function TGFBR1 mutations and MSSE. This distinguishes MSSE from the Marfan syndrome-related disorders in which missense mutations in TGFBR1 lead to developmental defects with vascular involvement but no reported predisposition to cancer....

Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1

DEFF Research Database (Denmark)

Goudie, David R; D'Alessandro, Mariella; Merriman, Barry

2011-01-01

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith disease (FSD), is an autosomal-dominant skin cancer condition characterized by multiple squamous-carcinoma-like locally invasive skin tumors that grow rapidly for a few weeks before spontaneously regressing, leaving......-of-function TGFBR1 mutations and MSSE. This distinguishes MSSE from the Marfan syndrome-related disorders in which missense mutations in TGFBR1 lead to developmental defects with vascular involvement but no reported predisposition to cancer....

High Mutation Levels are Compatible with Normal Embryonic Development in Mlh1-Deficient Mice.

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Fan, Xiaoyan; Li, Yan; Zhang, Yulong; Sang, Meixiang; Cai, Jianhui; Li, Qiaoxia; Ozaki, Toshinori; Ono, Tetsuya; He, Dongwei

2016-10-01

To elucidate the role of the mismatch repair gene Mlh1 in genome instability during the fetal stage, spontaneous mutations were studied in Mlh1-deficient lacZ-transgenic mouse fetuses. Mutation levels were high at 9.5 days post coitum (dpc) and gradually increased during the embryonic stage, after which they remained unchanged. In addition, mutations that were found in brain, liver, spleen, small intestine and thymus showed similar levels and no statistically significant difference was found. The molecular nature of mutations at 12.5 dpc in fetuses of Mlh1 +/+ and Mlh1 -/- mice showed their own unique spectra, suggesting that deletion mutations were the main causes in the deficiency of the Mlh1 gene. Of note, fetuses of irradiated mice exhibited marked differences such as post-implantation loss and Mendelian distribution. Collectively, these results strongly suggest that high mutation ofMlh1 -/- -deficient fetuses has little effect on the fetuses during their early developmental stages, whereas Mlh1 -/- -deficient fetuses from X-ray irradiated mothers are clearly effected.

Tooth display and lip position during spontaneous and posed smiling in adults.

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Van Der Geld, Pieter; Oosterveld, Paul; Berge, Stefaan J; Kuijpers-Jagtman, Anne M

2008-08-01

To analyze differences in tooth display, lip-line height, and smile width between the posed smiling record, traditionally produced for orthodontic diagnosis, and the spontaneous (Duchenne) smile of joy. The faces of 122 male participants were each filmed during spontaneous and posed smiling. Spontaneous smiles were elicited through the participants watching a comical movie. Maxillary and mandibular lip-line heights, tooth display, and smile width were measured using a digital videographic method for smile analysis. Paired sample t-tests were used to compare measurements of posed and spontaneous smiling. Maxillary lip-line heights during spontaneous smiling were significantly higher than during posed smiling. Compared to spontaneous smiling, tooth display in the (pre)molar area during posed smiling decreased by up to 30%, along with a significant reduction of smile width. During posed smiling, also mandibular lip-line heights changed and the teeth were more covered by the lower lip than during spontaneous smiling. Reduced lip-line heights, tooth display, and smile width on a posed smiling record can have implications for the diagnostics of lip-line height, smile arc, buccal corridors, and plane of occlusion. Spontaneous smiling records next to posed smiling records are therefore recommended for diagnostic purposes. Because of the dynamic nature of spontaneous smiling, it is proposed to switch to dynamic video recording of the smile.

The combined effect of two mutations that alter serially homologous color pattern elements on the fore and hindwings of a butterfly

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Vedder Lindsey

2007-05-01

Full Text Available Abstract Background The ability for serially homologous structures to acquire a separate identity has been primarily investigated for structures dependent on Hox gene input but is still incompletely understood in other systems. The fore and hindwings of butterflies are serially homologous structures as are the serially homologous eyespots that can decorate each of these wings. Eyespots can vary in number between fore and hindwings of the same individual and mutations of large effect can control the total number of eyespots that each of the wings displays. Here we investigate the genetics of a new spontaneous color pattern mutation, Missing, that alters eyespot number in the nymphalid butterfly, Bicyclus anynana. We further test the interaction of Missing with a previously described mutation, Spotty, describe the developmental stage affected by Missing, and test whether Missing is a mutant variant of the gene Distal-less via a linkage association study. Results Missing removes or greatly reduces the size of two of the hindwing eyespots from the row of seven eyespots, with no detectable effect on the rest of the wing pattern. Offspring carrying a single Missing allele display intermediate sized eyespots at these positions. Spotty has the opposite effect of Missing, i.e., it introduces two extra eyespots in homologous wing positions to those affected by Missing, but on the forewing. When Missing is combined with Spotty the size of the two forewing eyespots decreases but the size of the hindwing spots stays the same, suggesting that these two mutations have a combined effect on the forewing such that Missing reduces eyespot size when in the presence of a Spotty mutant allele, but that Spotty has no effect on the hindwing. Missing prevents the complete differentiation of two of the eyespot foci on the hindwing. We found no evidence for any linkage between the Distal-less and Missing genes. Conclusion The spontaneous mutation Missing controls the

Apert Syndrome With FGFR2 758 C > G Mutation: A Chinese Case Report

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Yahong Li

2018-05-01

Full Text Available Background: Apert syndrome is considered as one of the most common craniosynostosis syndromes with a prevalence of 1 in 65,000 individuals, and has a close relationship with point mutations in FGFR2 gene.Case report: Here, we described a Apert syndrome case, who was referred to genetic consultation in our hospital with the symptom of craniosynostosis and syndactyly of the hands and feet. Craniosynostosis, midfacial retrusion, steep wide forehead, larger head circumference, marked depression of the nasal bridge, short and wide nose and proptosis could be found obviously, apart from these, ears were mildly low compared with normal children and there was no cleft lip and palate. Mutation was identified by sanger sequencing and a mutation in the exon 7 of FGFR2 gene was detected: p.Pro253Arg (P253R 758 C > G, which was not found in his parents.Conclusion: The baby had Apert syndrome caused by 758 C > G mutation in the exon 7 of FGFR2 gene, considering no this mutation in his parents, it was spontaneous.

Gene expression profiling and candidate gene resequencing identifies pathways and mutations important for malignant transformation caused by leukemogenic fusion genes.

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Novak, Rachel L; Harper, David P; Caudell, David; Slape, Christopher; Beachy, Sarah H; Aplan, Peter D

2012-12-01

NUP98-HOXD13 (NHD13) and CALM-AF10 (CA10) are oncogenic fusion proteins produced by recurrent chromosomal translocations in patients with acute myeloid leukemia (AML). Transgenic mice that express these fusions develop AML with a long latency and incomplete penetrance, suggesting that collaborating genetic events are required for leukemic transformation. We employed genetic techniques to identify both preleukemic abnormalities in healthy transgenic mice as well as collaborating events leading to leukemic transformation. Candidate gene resequencing revealed that 6 of 27 (22%) CA10 AMLs spontaneously acquired a Ras pathway mutation and 8 of 27 (30%) acquired an Flt3 mutation. Two CA10 AMLs acquired an Flt3 internal-tandem duplication, demonstrating that these mutations can be acquired in murine as well as human AML. Gene expression profiles revealed a marked upregulation of Hox genes, particularly Hoxa5, Hoxa9, and Hoxa10 in both NHD13 and CA10 mice. Furthermore, mir196b, which is embedded within the Hoxa locus, was overexpressed in both CA10 and NHD13 samples. In contrast, the Hox cofactors Meis1 and Pbx3 were differentially expressed; Meis1 was increased in CA10 AMLs but not NHD13 AMLs, whereas Pbx3 was consistently increased in NHD13 but not CA10 AMLs. Silencing of Pbx3 in NHD13 cells led to decreased proliferation, increased apoptosis, and decreased colony formation in vitro, suggesting a previously unexpected role for Pbx3 in leukemic transformation. Published by Elsevier Inc.

Clinical and molecular analyses of Beckwith-Wiedemann syndrome: Comparison between spontaneous conception and assisted reproduction techniques.

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Tenorio, Jair; Romanelli, Valeria; Martin-Trujillo, Alex; Fernández, García-Moya; Segovia, Mabel; Perandones, Claudia; Pérez Jurado, Luis A; Esteller, Manel; Fraga, Mario; Arias, Pedro; Gordo, Gema; Dapía, Irene; Mena, Rocío; Palomares, María; Pérez de Nanclares, Guiomar; Nevado, Julián; García-Miñaur, Sixto; Santos-Simarro, Fernando; Martinez-Glez, Víctor; Vallespín, Elena; Monk, David; Lapunzina, Pablo

2016-10-01

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome characterized by an excessive prenatal and postnatal growth, macrosomia, macroglossia, and hemihyperplasia. The molecular basis of this syndrome is complex and heterogeneous, involving genes located at 11p15.5. BWS is correlated with assisted reproductive techniques. BWS in individuals born following assisted reproductive techniques has been found to occur four to nine times higher compared to children with to BWS born after spontaneous conception. Here, we report a series of 187 patients with to BWS born either after assisted reproductive techniques or conceived naturally. Eighty-eight percent of BWS patients born via assisted reproductive techniques had hypomethylation of KCNQ1OT1:TSS-DMR in comparison with 49% for patients with BWS conceived naturally. None of the patients with BWS born via assisted reproductive techniques had hypermethylation of H19/IGF2:IG-DMR, neither CDKN1 C mutations nor patUPD11. We did not find differences in the frequency of multi-locus imprinting disturbances between groups. Patients with BWS born via assisted reproductive techniques had an increased frequency of advanced bone age, congenital heart disease, and decreased frequency of earlobe anomalies but these differences may be explained by the different molecular background compared to those with BWS and spontaneous fertilization. We conclude there is a correlation of the molecular etiology of BWS with the type of conception. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Spontaneous Spreading of a Droplet: The Role of Solid Continuity and Advancing Contact Angle.

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Jiang, Youhua; Sun, Yujin; Drelich, Jaroslaw W; Choi, Chang-Hwan

2018-05-01

Spontaneous spreading of a droplet on a solid surface is poorly understood from a macroscopic level down to a molecular level. Here, we investigate the effect of surface topography and wettability on spontaneous spreading of a water droplet. Spreading force is measured for a suspended droplet that minimizes interference of kinetic energy in the spontaneous spreading during its contact with solid surfaces of discontinuous (pillar) and continuous (pore) patterns with various shapes and dimensions. Results show that a droplet cannot spread spontaneously on pillared surfaces regardless of their shapes or dimensions because of the solid discontinuity. On the contrary, a droplet on pored surfaces can undergo spontaneous spreading whose force increases with a decrease in the advancing contact angle. Theoretical models based on both the system free energy and capillary force along the contact line validate the direct and universal dependency of the spontaneous spreading force on the advancing contact angle.

Mutation directional selection sheds light on prion pathogenesis

International Nuclear Information System (INIS)

Shen, Liang; Ji, Hong-Fang

2011-01-01

Highlights: → Most pathogenic mutations possess strong directional selection, i.e., enhancing hydrophobicity or decreasing negative and increasing positive charge. → Mutation-induced changes may strengthen the interactions between PrP and facilitating factors. → The findings also have significant implications for exploring potential regions involved in the conformational transition from PrP C to PrP Sc . -- Abstract: As mutations in the PRNP gene account for human hereditary prion diseases (PrDs), it is crucial to elucidating how these mutations affect the central pathogenic conformational transition of normal cellular prion protein (PrP C ) to abnormal scrapie isoform (PrP Sc ). Many studies proposed that these pathogenic mutations may make PrP more susceptible to conformational change through altering its structure stability. By evaluating the most recent observations regarding pathogenic mutations, it was found that the pathogenic mutations do not exert a uniform effect on the thermodynamic stability of the human PrP's structure. Through analyzing the reported PrDs-related mutations, we found that 25 out of 27 mutations possess strong directional selection, i.e., enhancing hydrophobicity or decreasing negative and increasing positive charge. Based on the triggering role reported by previous studies of facilitating factors in PrP C conversion, e.g., lipid and polyanion, we proposed that the mutation-induced changes may strengthen the interaction between PrP and facilitating factors, which will accelerate PrP conversion and cause PrDs.

Mutation directional selection sheds light on prion pathogenesis

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Shen, Liang [Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255049 (China); Ji, Hong-Fang, E-mail: jhf@sdut.edu.cn [Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255049 (China)

2011-07-01

Highlights: {yields} Most pathogenic mutations possess strong directional selection, i.e., enhancing hydrophobicity or decreasing negative and increasing positive charge. {yields} Mutation-induced changes may strengthen the interactions between PrP and facilitating factors. {yields} The findings also have significant implications for exploring potential regions involved in the conformational transition from PrP{sup C} to PrP{sup Sc}. -- Abstract: As mutations in the PRNP gene account for human hereditary prion diseases (PrDs), it is crucial to elucidating how these mutations affect the central pathogenic conformational transition of normal cellular prion protein (PrP{sup C}) to abnormal scrapie isoform (PrP{sup Sc}). Many studies proposed that these pathogenic mutations may make PrP more susceptible to conformational change through altering its structure stability. By evaluating the most recent observations regarding pathogenic mutations, it was found that the pathogenic mutations do not exert a uniform effect on the thermodynamic stability of the human PrP's structure. Through analyzing the reported PrDs-related mutations, we found that 25 out of 27 mutations possess strong directional selection, i.e., enhancing hydrophobicity or decreasing negative and increasing positive charge. Based on the triggering role reported by previous studies of facilitating factors in PrP{sup C} conversion, e.g., lipid and polyanion, we proposed that the mutation-induced changes may strengthen the interaction between PrP and facilitating factors, which will accelerate PrP conversion and cause PrDs.

Mutation types and aging differently affect revertant fiber expansion in dystrophic mdx and mdx52 mice.

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Yusuke Echigoya

Full Text Available Duchenne muscular dystrophy (DMD, one of the most common and lethal genetic disorders, and the mdx mouse myopathies are caused by a lack of dystrophin protein. These dystrophic muscles contain sporadic clusters of dystrophin-expressing revertant fibers (RFs, as detected by immunohistochemistry. RFs are known to arise from muscle precursor cells with spontaneous exon skipping (alternative splicing and clonally expand in size with increasing age through the process of muscle degeneration/regeneration. The expansion of revertant clusters is thought to represent the cumulative history of muscle regeneration and proliferation of such precursor cells. However, the precise mechanisms by which RFs arise and expand are poorly understood. Here, to test the effects of mutation types and aging on RF expansion and muscle regeneration, we examined the number of RFs in mdx mice (containing a nonsense mutation in exon 23 and mdx52 mice (containing deletion mutation of exon 52 with the same C57BL/6 background at 2, 6, 12, and 18months of age. Mdx mice displayed a significantly higher number of RFs compared to mdx52 mice in all age groups, suggesting that revertant fiber expansion largely depends on the type of mutation and/or location in the gene. A significant increase in the expression and clustering levels of RFs was found beginning at 6months of age in mdx mice compared with mdx52 mice. In contrast to the significant expansion of RFs with increasing age, the number of centrally nucleated fibers and embryonic myosin heavy chain-positive fibers (indicative of cumulative and current muscle regeneration, respectively decreased with age in both mouse strains. These results suggest that mutation types and aging differently affect revertant fiber expansion in mdx and mdx52 mice.

Mutations of the Birt–Hogg–Dubé gene in patients with multiple lung cysts and recurrent pneumothorax

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Gunji, Yoko; Akiyoshi, Taeko; Sato, Teruhiko; Kurihara, Masatoshi; Tominaga, Shigeru; Takahashi, Kazuhisa; Seyama, Kuniaki

2007-01-01

Rationale Birt–Hogg–Dubé (BHD) syndrome, a rare inherited autosomal genodermatosis first recognised in 1977, is characterised by fibrofolliculomas of the skin, an increased risk of renal tumours and multiple lung cysts with spontaneous pneumothorax. The BHD gene, a tumour suppressor gene located at chromosome 17p11.2, has recently been shown to be defective. Recent genetic studies revealed that clinical pictures of the disease may be variable and may not always present the full expression of the phenotypes. Objectives We hypothesised that mutations of the BHD gene are responsible for patients who have multiple lung cysts of which the underlying causes have not yet been elucidated. Methods We studied eight patients with lung cysts, without skin and renal disease; seven of these patients have a history of spontaneous pneumothorax and five have a family history of pneumothorax. The BHD gene was examined using PCR, denaturing high‐performance liquid chromatography and direct sequencing. Main results We found that five of the eight patients had a BHD germline mutation. All mutations were unique and four of them were novel, including three different deletions or insertions detected in exons 6, 12 and 13, respectively and one splice acceptor site mutation in intron 5 resulting in an in‐frame deletion of exon 6. Conclusions We found that germline mutations of the BHD gene are involved in some patients with multiple lung cysts and pneumothorax. Pulmonologists should be aware that BHD syndrome can occur as an isolated phenotype with pulmonary involvement. PMID:17496196

The Effect of Live Spontaneous Harp Music on Patients in the Intensive Care Unit

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Ann Marie Chiasson

2013-01-01

Full Text Available This study was performed to investigate the effect of live, spontaneous harp music on individual patients in an intensive care unit (ICU, either pre- or postoperatively. The purpose was to determine whether this intervention would serve as a relaxation or healing modality, as evidenced by the effect on patient’s pain, heart rate, respiratory rate, blood pressure, oxygen saturation, and heart rate variability. Each consenting patient was randomly assigned to receive either a live 10-minute concert of spontaneous music played by an expert harpist or a 10-minute rest period. Spontaneous harp music significantly decreased patient perception of pain by 27% but did not significantly affect heart rate, respiratory rate, oxygen saturation, blood pressure, or heart rate variability. Trends emerged, although being not statistically significant, that systolic blood pressure increased while heart rate variability decreased. These findings may invoke patient engagement, as opposed to relaxation, as the underlying mechanism of the decrease in the patients’ pain and of the healing benefit that arises from the relationship between healer, healing modality, and patient.

Extralobar pulmonary sequestration in neonates: The natural course and predictive factors associated with spontaneous regression

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Yoon, Hee Mang; Jung, Ah Young; Cho, Young Ah; Yoon, Chong Hyun; Lee, Jin Seong [Asan Medical Center Children' s Hospital, University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Songpa-gu, Seoul (Korea, Republic of); Kim, Ellen Ai-Rhan [University of Ulsan College of Medicine, Division of Neonatology, Asan Medical Center Children' s Hospital, Seoul (Korea, Republic of); Chung, Sung-Hoon [Kyung Hee University School of Medicine, Department of Pediatrics, Seoul (Korea, Republic of); Kim, Seon-Ok [Asan Medical Center, Department of Clinical Epidemiology and Biostatistics, Seoul (Korea, Republic of)

2017-06-15

To describe the natural course of extralobar pulmonary sequestration (EPS) and identify factors associated with spontaneous regression of EPS. We retrospectively searched for patients diagnosed with EPS on initial contrast CT scan within 1 month after birth and had a follow-up CT scan without treatment. Spontaneous regression of EPS was assessed by percentage decrease in volume (PDV) and percentage decrease in sum of the diameter of systemic feeding arteries (PDD) by comparing initial and follow-up CT scans. Clinical and CT features were analysed to determine factors associated with PDV and PDD rates. Fifty-one neonates were included. The cumulative proportions of patients reaching PDV > 50 % and PDD > 50 % were 93.0 % and 73.3 % at 4 years, respectively. Tissue attenuation was significantly associated with PDV rate (B = -21.78, P <.001). The tissue attenuation (B = -22.62, P =.001) and diameter of the largest systemic feeding arteries (B = -48.31, P =.011) were significant factors associated with PDD rate. The volume and diameter of systemic feeding arteries of EPS spontaneously decreased within 4 years without treatment. EPSs showing a low tissue attenuation and small diameter of the largest systemic feeding arteries on initial contrast-enhanced CT scans were likely to regress spontaneously. (orig.)

A novel loss-of-function mutation in GPR54/KISS1R leads to hypogonadotropic hypogonadism in a highly consanguineous family.

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Nimri, Revital; Lebenthal, Yael; Lazar, Liora; Chevrier, Lucie; Phillip, Moshe; Bar, Meytal; Hernandez-Mora, Eva; de Roux, Nicolas; Gat-Yablonski, Galia

2011-03-01

The G protein-coupled receptor 54 (GPR54), the kisspeptin receptor, is essential for stimulation of GnRH secretion and induction of puberty. Recently loss-of-function mutations of the GPR54 have been implicated as a cause of isolated idiopathic hypogonadotropic hypogonadism (IHH). The objective of the study was to identify the genetic cause of IHH in a consanguineous pedigree and to characterize the phenotypic features from infancy through early adulthood. In six patients with normosmic IHH belonging to two families of Israeli Muslim-Arab origin highly related to one another, DNA was analyzed for mutations in the GnRHR and GPR54 genes, with functional analysis of the mutation found. The five males underwent comprehensive endocrine evaluation and were under longitudinal follow-up; the one female presented in early adulthood. A new homozygous mutation (c.T815C) in GPR54 leading to a phenylalanine substitution by serine (p.F272S) was detected in all patients. Functional analysis showed an almost complete inhibition of kisspeptin-induced GPR54 signaling and a dramatic decrease of the mutated receptor expression at the cell surface. The males exhibited the same clinical features from infancy to adulthood, characterized by cryptorchidism, a relatively short penis, and no spontaneous pubertal development. The female patient presented at 18 yr with impuberism and primary amenorrhea. Repeated stimulation tests demonstrated complete gonadotropin deficiency throughout follow-up. A novel loss-of-function mutation (p.F272S) in the GPR54 gene is associated with familial normosmic IHH. Underdeveloped external genitalia and impuberism point to the major role of GPR54 in the activation of the gonadotropic axis from intrauterine life to adulthood.

Effect of postirradiation storage of seeds on the structural chromosomal mutations in chlorophyll mutants of sunflower (Helianthus annuus L)

International Nuclear Information System (INIS)

Sizova, L.I.

1976-01-01

The paper comprises the results of the investigation of the storage effect in irradiated seeds on the frequency and the spectrum of structural mutations of chromosomes in normal green plants and in spontaneous chlorophyll mutants of sunflower. The seeds of chlorophyll mutants lutescens and xantha and those of green plants stored for 3 years have been 60 Co gamma-irradiated with doses of 0.5; 1.0; 2.0; 3.0; 5.0 and 10 kr. After the irradiation the seeds have been stored for a year under conventional laboratory conditions. As a result of the post-irradiation storage of seeds for a year the decrease in the proportion of aberrant cells by 3 to 6% at the expense of cells with paired fragments has been observed in green plants. In chlorophyll mutants the storage of seeds after the irradiation results in the 9 to 37% increase of the proportion of aberrant cells at the expense of cells with single and paired bridges and with paired fragments. This gives evidence in favour of the assumption that in spontaneous chlorophyll mutants the processes of the post-irradiation recovery either fail altogether, or proceed at a very low level

Spontaneous Clearance of Hepatitis C after Liver and Renal Transplantation

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CH Dale

2009-01-01

Full Text Available Spontaneous clearance of hepatitis C virus (HCV is rare in immunocompromised patients, such as those who have undergone organ transplantation. It has been recognized that patients receiving liver transplantation for HCV-related disease have decreased graft and patient survival compared with those transplanted for other etiologies. There is a growing trend toward treating HCV recurrence aggressively after liver transplantation. For other organ transplant recipients with concurrent HCV, treatment is not often an option, given the high rates of graft rejection and loss secondary to interferon and its immunomodulatory effects. Although spontaneous clearance of HCV has been reported in recipients of solitary liver and renal transplants, a common factor arising in these cases has been previous exposure to interferon. To date, no reports of spontaneous clearance of HCV RNA have been reported in a multiorgan transplant recipient. A case of spontaneous clearance of HCV RNA in an immunocompromised patient, within five months of simultaneous liver and kidney retransplantation is described. Importantly, this patient had no previous exposure to interferon.

Transcriptome analysis of a spontaneous mutant in sweet orange [Citrus sinensis (L.) Osbeck] during fruit development.

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Liu, Qing; Zhu, Andan; Chai, Lijun; Zhou, Wenjing; Yu, Keqin; Ding, Jian; Xu, Juan; Deng, Xiuxin

2009-01-01

Bud mutations often arise in citrus. The selection of mutants is one of the most important breeding channels in citrus. However, the molecular basis of bud mutation has rarely been studied. To identify differentially expressed genes in a spontaneous sweet orange [C. sinensis (L.) Osbeck] bud mutation which causes lycopene accumulation, low citric acid, and high sucrose in fruit, suppression subtractive hybridization and microarray analysis were performed to decipher this bud mutation during fruit development. After sequencing of the differentially expressed clones, a total of 267 non-redundant transcripts were obtained and 182 (68.2%) of them shared homology (E-value or = 2) in the bud mutation during fruit development. Self-organizing tree algorithm analysis results showed that 95.1% of the differentially expressed genes were extensively coordinated with the initiation of lycopene accumulation. Metabolic process, cellular process, establishment of localization, response to stimulus, and biological regulation-related transcripts were among the most regulated genes. These genes were involved in many biological processes such as organic acid metabolism, lipid metabolism, transport, and pyruvate metabolism, etc. Moreover, 13 genes which were differentially regulated at 170 d after flowering shared homology with previously described signal transduction or transcription factors. The information generated in this study provides new clues to aid in the understanding of bud mutation in citrus.

Spontaneous and trigger-associated substorms compared: Electrodynamic parameters in the polar ionosphere

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Liu, Jun-Ming; Zhang, Bei-Chen; Kamide, Y.; Wu, Zhen-Sen; Hu, Ze-Jun; Yang, Hui-Gen

2011-01-01

An attempt is made to study the difference, if any, between the response of the polar ionosphere to spontaneous substorms and that to trigger-associated substorms in terms of electrodynamic parameters including ionospheric current vectors, the electric potential, and the current function. The results show that, in the first approximation, the ionospheric parameters for the two types of substorms are quite similar. It is therefore conceived that spontaneous substorms are not very different from trigger-associated substorms in the development of substorm processes in the magnetosphere-ionosphere system. We demonstrate, however, that spontaneous substorms seem to have a more clearly identifiable growth phase, whereas trigger-associated substorms have a more powerful unloading process. Changes in the current intensity and the electric potential drop across the polar cap in the recovery phase are also quite different from each other. Both the current intensity and the cross-polar cap potential drop show a larger decrease in the recovery phase of trigger-associated substorms, but the potential drop decreases only slightly and the currents in the late morning sector are still strong for spontaneous substorms. We interpret these findings as an indication of the relative importance of the unloading process and the directly driven process in conjunction with the north-south polarity of the interplanetary magnetic field. There still exists a strong directly driven process in the recovery phase of spontaneous substorms. For trigger-associated substorms, however, both the directly driven process and the unloading process become weak after the peak time.

Ferredoxin Gene Mutation in Iranian Trichomonas Vaginalis Isolates

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Soudabeh Heidari

2013-09-01

Full Text Available Background: Trichomonas vaginalis causes trichomoniasis and metronidazole is its chosen drug for treatment. Ferredoxin has role in electron transport and carbohydrate metabolism and the conversion of an inactive form of metronidazole (CO to its active form (CPR. Ferredoxin gene mutations reduce gene expression and increase its resistance to metronidazole. In this study, the frequency of ferredoxin gene mutations in clinical isolates of T.vaginalis in Tehran has been studied.Methods: Forty six clinical T. vaginalis isolates of vaginal secretions and urine sediment were collected from Tehran Province since 2011 till 2012. DNA was extracted and ferredoxin gene was amplified by PCR technique. The ferredoxin gene PCR products were sequenced to determine gene mutations.Results: In four isolates (8.69% point mutation at nucleotide position -239 (the translation start codon of the ferredoxin gene were detected in which adenosine were converted to thymine.Conclusion: Mutation at nucleotide -239 ferredoxin gene reduces translational regulatory protein’s binding affinity which concludes reduction of ferredoxin expression. For this reduction, decrease in activity and decrease in metronidazole drug delivery into the cells occur. Mutations in these four isolates may lead to resistance of them to metronidazole.

Motor and Sensory Deficits in the teetering Mice Result from Mutation of the ESCRT Component HGS.

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Jennifer A Watson

2015-06-01

Full Text Available Neurons are particularly vulnerable to perturbations in endo-lysosomal transport, as several neurological disorders are caused by a primary deficit in this pathway. In this report, we used positional cloning to show that the spontaneously occurring neurological mutation teetering (tn is a single nucleotide substitution in hepatocyte growth factor-regulated tyrosine kinase substrate (Hgs/Hrs, a component of the endosomal sorting complex required for transport (ESCRT. The tn mice exhibit hypokenesis, muscle weakness, reduced muscle size and early perinatal lethality by 5-weeks of age. Although HGS has been suggested to be essential for the sorting of ubiquitinated membrane proteins to the lysosome, there were no alterations in receptor tyrosine kinase levels in the central nervous system, and only a modest decrease in tropomyosin receptor kinase B (TrkB in the sciatic nerves of the tn mice. Instead, loss of HGS resulted in structural alterations at the neuromuscular junction (NMJ, including swellings and ultra-terminal sprouting at motor axon terminals and an increase in the number of endosomes and multivesicular bodies. These structural changes were accompanied by a reduction in spontaneous and evoked release of acetylcholine, indicating a deficit in neurotransmitter release at the NMJ. These deficits in synaptic transmission were associated with elevated levels of ubiquitinated proteins in the synaptosome fraction. In addition to the deficits in neuronal function, mutation of Hgs resulted in both hypermyelinated and dysmyelinated axons in the tn mice, which supports a growing body of evidence that ESCRTs are required for proper myelination of peripheral nerves. Our results indicate that HGS has multiple roles in the nervous system and demonstrate a previously unanticipated requirement for ESCRTs in the maintenance of synaptic transmission.

Mutations in 23S rRNA gene associated with decreased susceptibility to tiamulin and valnemulin in Mycoplasma gallisepticum.

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Li, Bei-Bei; Shen, Jian-Zhong; Cao, Xing-Yuan; Wang, Yang; Dai, Lei; Huang, Si-Yang; Wu, Cong-Ming

2010-07-01

Mycoplasma gallisepticum is a major etiological agent of chronic respiratory disease (CRD) in chickens and sinusitis in turkeys. The pleuromutilin antibiotics tiamulin and valnemulin are currently used in the treatment of M. gallisepticum infection. We studied the in vitro development of pleuromutilin resistance in M. gallisepticum and investigated the molecular mechanisms involved in this process. Pleuromutilin-resistant mutants were selected by serial passages of M. gallisepticum strains PG31 and S6 in broth medium containing subinhibitory concentrations of tiamulin or valnemulin. A portion of the gene encoding 23S rRNA gene (domain V) and the gene encoding ribosome protein L3 were amplified and sequenced. No mutation could be detected in ribosome protein L3. Mutations were found at nucleotide positions 2058, 2059, 2061, 2447 and 2503 of 23S rRNA gene (Escherichia coli numbering). Although a single mutation could cause elevation of tiamulin and valnemulin MICs, combinations of two or three mutations were necessary to produce high-level resistance. All the mutants were cross-resistant to lincomycin, chloramphenicol and florfenicol. Mutants with the A2058G or the A2059G mutation exhibited cross-resistance to macrolide antibiotics erythromycin, tilmicosin and tylosin.

Spontaneous acute spinal subdural hematoma: spontaneous recovery from severe paraparesis--case report and review.

Science.gov (United States)

Payer, Michael; Agosti, Reto

2010-11-01

Spontaneous idiopathic acute spinal subdural hematomas are highly exceptional. Neurological symptoms are usually severe, and rapid diagnosis with MRI is mandatory. Surgical evacuation has frequently been used therapeutically; however, spontaneous recovery in mild cases has also been reported. We present a case of spontaneous recovery from severe paraparesis after spontaneous acute SSDH, and review the English-speaking literature.

Effects of Mutations on Structure-Function Relationships of Matrix Metalloproteinase-1.

Science.gov (United States)

Singh, Warispreet; Fields, Gregg B; Christov, Christo Z; Karabencheva-Christova, Tatyana G

2016-10-14

Matrix metalloproteinase-1 (MMP-1) is one of the most widely studied enzymes involved in collagen degradation. Mutations of specific residues in the MMP-1 hemopexin-like (HPX) domain have been shown to modulate activity of the MMP-1 catalytic (CAT) domain. In order to reveal the structural and conformational effects of such mutations, a molecular dynamics (MD) study was performed of in silico mutated residues in the X-ray crystallographic structure of MMP-1 complexed with a collagen-model triple-helical peptide (THP). The results indicate an important role of the mutated residues in MMP-1 interactions with the THP and communication between the CAT and the HPX domains. Each mutation has a distinct impact on the correlated motions in the MMP-1•THP. An increased collagenase activity corresponded to the appearance of a unique anti-correlated motion and decreased correlated motions, while decreased collagenase activity corresponded both to increased and decreased anti-correlated motions.

Effects of Mutations on Structure–Function Relationships of Matrix Metalloproteinase-1

Directory of Open Access Journals (Sweden)

Warispreet Singh

2016-10-01

Full Text Available Matrix metalloproteinase-1 (MMP-1 is one of the most widely studied enzymes involved in collagen degradation. Mutations of specific residues in the MMP-1 hemopexin-like (HPX domain have been shown to modulate activity of the MMP-1 catalytic (CAT domain. In order to reveal the structural and conformational effects of such mutations, a molecular dynamics (MD study was performed of in silico mutated residues in the X-ray crystallographic structure of MMP-1 complexed with a collagen-model triple-helical peptide (THP. The results indicate an important role of the mutated residues in MMP-1 interactions with the THP and communication between the CAT and the HPX domains. Each mutation has a distinct impact on the correlated motions in the MMP-1•THP. An increased collagenase activity corresponded to the appearance of a unique anti-correlated motion and decreased correlated motions, while decreased collagenase activity corresponded both to increased and decreased anti-correlated motions.

Non-homologous end joining dependency of {gamma}-irradiation-induced adaptive frameshift mutation formation in cell cycle-arrested yeast cells

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Heidenreich, Erich [Institute of Cancer Research, Division of Molecular Genetics, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna (Austria)]. E-mail: erich.heidenreich@meduniwien.ac.at; Eisler, Herfried [Institute of Cancer Research, Division of Molecular Genetics, Medical University of Vienna, Borschkegasse 8a, A-1090 Vienna (Austria)

2004-11-22

There is a strong selective pressure favoring adaptive mutations which relieve proliferation-limiting adverse living conditions. Due to their importance for evolution and pathogenesis, we are interested in the mechanisms responsible for the formation of such adaptive, gain-of-fitness mutations in stationary-phase cells. During previous studies on the occurrence of spontaneous reversions of an auxotrophy-causing frameshift allele in the yeast Saccharomyces cerevisiae, we noticed that about 50% of the adaptive reversions depended on a functional non-homologous end joining (NHEJ) pathway of DNA double-strand break (DSB) repair. Here, we show that the occasional NHEJ component Pol4, which is the yeast ortholog of mammalian DNA polymerase lambda, is not required for adaptive mutagenesis. An artificially imposed excess of DSBs by {gamma}-irradiation resulted in a dramatic increase in the incidence of adaptive, cell cycle arrest-releasing frameshift reversions. By the use of DNA ligase IV-deficient strains we detected that the majority of the {gamma}-induced adaptive mutations were also dependent on a functional NHEJ pathway. This suggests that the same mutagenic NHEJ mechanism acts on spontaneously arising as well as on ionizing radiation-induced DSBs. Inaccuracy of the NHEJ repair pathway may extensively contribute to the incidence of frameshift mutations in resting (non-dividing) eukaryotic cells, and thus act as a driving force in tumor development.

Non-homologous end joining dependency of γ-irradiation-induced adaptive frameshift mutation formation in cell cycle-arrested yeast cells

International Nuclear Information System (INIS)

Heidenreich, Erich; Eisler, Herfried

2004-01-01

There is a strong selective pressure favoring adaptive mutations which relieve proliferation-limiting adverse living conditions. Due to their importance for evolution and pathogenesis, we are interested in the mechanisms responsible for the formation of such adaptive, gain-of-fitness mutations in stationary-phase cells. During previous studies on the occurrence of spontaneous reversions of an auxotrophy-causing frameshift allele in the yeast Saccharomyces cerevisiae, we noticed that about 50% of the adaptive reversions depended on a functional non-homologous end joining (NHEJ) pathway of DNA double-strand break (DSB) repair. Here, we show that the occasional NHEJ component Pol4, which is the yeast ortholog of mammalian DNA polymerase lambda, is not required for adaptive mutagenesis. An artificially imposed excess of DSBs by γ-irradiation resulted in a dramatic increase in the incidence of adaptive, cell cycle arrest-releasing frameshift reversions. By the use of DNA ligase IV-deficient strains we detected that the majority of the γ-induced adaptive mutations were also dependent on a functional NHEJ pathway. This suggests that the same mutagenic NHEJ mechanism acts on spontaneously arising as well as on ionizing radiation-induced DSBs. Inaccuracy of the NHEJ repair pathway may extensively contribute to the incidence of frameshift mutations in resting (non-dividing) eukaryotic cells, and thus act as a driving force in tumor development

Laser-induced electron--ion recombination used to study enhanced spontaneous recombination during electron cooling

International Nuclear Information System (INIS)

Schramm, U.; Wolf, A.; Schuess ler, T.; Habs, D.; Schwalm, D.; Uwira, O.; Linkemann, J.; Mueller, A.

1997-01-01

Spontaneous recombination of highly charged ions with free electrons in merged velocity matched electron and ion beams has been observed in earlier experiments to occur at rates significantly higher than predicted by theoretical estimates. To study this enhanced spontaneous recombination, laser induced recombination spectra were measured both in velocity matched beams and in beams with well defined relative velocities, corresponding to relative electron-ion detuning energies ranging from 1 meV up to 6.5 meV where the spontaneous recombination enhancement was found to be strongly reduced. Based on a comparison with simplified calculations, the development of the recombination spectra for decreasing detuning energies indicates additional contributions at matched velocities which could be related to the energy distribution of electrons causing the spontaneous recombination rate enhancement

Methylmethane-sulphonate and X-ray-induced mutations in the Chinese hamster hprt gene: mRNA phenotyping using polymerase chain reactions

International Nuclear Information System (INIS)

Chaudhry, M.A.; Fox, Margaret

1990-01-01

Alterations in the hprt gene of Chinese hamster cells were determined in 71 spontaneous, methylmethane sulphonate (MMS)-and X-ray induced mutants, using the Southern blot hybridization technique. To investigate the possibility of small deletions, MMS-induced mutants were studied with proves derived from exons 3 and 9 but no evidence of specific deletion of these two exons was found. The polymerase chain reaction (PCR) was used to phenotype hprt transcripts in 48 MMS, X-ray and spontaneous Chinese hamster mutants by amplifying the coding region of their cDNA. Among 22 MMS-induced mutants the message was present in 16 instances. An analysis of 20 X-ray-induced mutants showed the presence of hprt mRNA in 11 of them with five having low levels of transcription. Among six spontaneous mutants, four were negative for mRNA on standard Northern blots and in one the message was only detected after PCR amplification. Direct DNA sequencing of 10 mutants revealed the presence of base substitutions in five of them while a 7 bp deletion was found in another. No mutations were found in another four mutants, suggesting the presence of mutation outside the coding region. (author)

Rare beneficial mutations can halt Muller's ratchet

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Balick, Daniel; Goyal, Sidhartha; Jerison, Elizabeth; Neher, Richard; Shraiman, Boris; Desai, Michael

2012-02-01

In viral, bacterial, and other asexual populations, the vast majority of non-neutral mutations are deleterious. This motivates the application of models without beneficial mutations. Here we show that the presence of surprisingly few compensatory mutations halts fitness decay in these models. Production of deleterious mutations is balanced by purifying selection, stabilizing the fitness distribution. However, stochastic vanishing of fitness classes can lead to slow fitness decay (i.e. Muller's ratchet). For weakly deleterious mutations, production overwhelms purification, rapidly decreasing population fitness. We show that when beneficial mutations are introduced, a stable steady state emerges in the form of a dynamic mutation-selection balance. We argue this state is generic for all mutation rates and population sizes, and is reached as an end state as genomes become saturated by either beneficial or deleterious mutations. Assuming all mutations have the same magnitude selective effect, we calculate the fraction of beneficial mutations necessary to maintain the dynamic balance. This may explain the unexpected maintenance of asexual genomes, as in mitochondria, in the presence of selection. This will affect in the statistics of genetic diversity in these populations.

Hormonal changes in spontaneous and aglépristone-induced parturition in dogs.

Science.gov (United States)

Baan, M; Taverne, M A M; de Gier, J; Kooistra, H S; Kindahl, H; Dieleman, S J; Okkens, A C

2008-03-01

To increase our understanding of the endocrine changes associated with parturition in dogs, plasma concentrations of progesterone (P4), 15-ketodihydroprostaglandin F(2alpha) (PGFM), estradiol-17-beta (E2beta), cortisol, ACTH, prolactin (PRL), LH, and FSH were measured in six spontaneously whelping bitches and in six bitches in which parturition was induced with the progesterone-receptor blocker aglépristone on day 58 of pregnancy. Expulsion of pups in the induced group took place in the presence of P4 concentrations that were still elevated. PGFM concentrations increased before parturition in both groups, but levels were lower in the induced bitches. PGFM levels reached a maximum in both groups during parturition and quickly decreased in the spontaneously whelping group after parturition, but remained elevated in the induced group. In both groups, cortisol concentrations reached similar maximum levels during the last 30 h before the onset of expulsion. During the 3 days postpartum, cortisol concentrations were higher in the induced group. The highly variable ACTH concentrations did not differ significantly throughout the study within or between groups. In both groups, E2beta concentrations decreased and PRL concentrations increased between the late gestational period and the 30-h period before parturition. Concentrations of both LH (spontaneously whelping group) and FSH (both groups) decreased between late gestation and the postpartum period. The results of this study illustrate the hormonal changes around parturition in the bitch, and reveal that aglépristone-induced parturition is associated with still incomplete luteolysis, an altered PGFM profile, and elevated postpartum cortisol concentrations as compared with spontaneously whelping dogs.

Egg ovotransferrin-derived ACE inhibitory peptide IRW increases ACE2 but decreases proinflammatory genes expression in mesenteric artery of spontaneously hypertensive rats.

Science.gov (United States)

Majumder, Kaustav; Liang, Guanxiang; Chen, Yanhong; Guan, LeLuo; Davidge, Sandra T; Wu, Jianping

2015-09-01

Egg ovotransferrin-derived angiotensin converting enzyme (ACE) inhibitory peptide IRW was previously shown to reduce blood pressure in spontaneously hypertensive rats through reduced vascular inflammation and increased nitric oxide-mediated vasorelaxation. The main objective of the present study was to investigate the molecular mechanism of this peptide through transcriptome analysis by RNAseq technique. Total RNA was extracted from kidney and mesenteric arteries; the RNAseq libraries (from untreated and IRW-treated groups) were constructed and subjected to sequence using HiSeq 2000 system (Illumina) system. A total of 12 764 and 13 352 genes were detected in kidney and mesenteric arteries, respectively. The differentially expressed (DE) genes between untreated and IRW-treated groups were identified and the functional analysis through ingenuity pathway analysis revealed a greater role of DE genes identified from mesenteric arteries than that of kidney in modulating various cardiovascular functions. Subsequent qPCR analysis further confirmed that IRW significantly increased the expression of ACE-2, ABCB-1, IRF-8, and CDH-1 while significantly decreased the expression ICAM-1 and VCAM-1 in mesenteric arteries. Our research showed for the first time that ACE inhibitory peptide IRW could contribute to its antihypertensive activity through increased ACE2 and decreased proinflammatory genes expression. © 2015 The Authors. Molecular Nutrition & Food Research published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Spontaneous inflammatory pain model from a mouse line with N-ethyl-N-nitrosourea mutagenesis

Directory of Open Access Journals (Sweden)

Chen Tsung-Chieh

2012-05-01

Full Text Available Abstract Background N-ethyl-N-nitrosourea mutagenesis was used to induce a point mutation in C57BL/6 J mice. Pain-related phenotype screening was performed in 915 G3 mice. We report the detection of a heritable recessive mutant in meiotic recombinant N1F1 mice that caused an abnormal pain sensitivity phenotype with spontaneous skin inflammation in the paws and ears. Methods We investigated abnormal sensory processing, neuronal peptides, and behavioral responses after the induction of autoinflammatory disease. Single-nucleotide polymorphism (SNP markers and polymerase chain reaction product sequencing were used to identify the mutation site. Results All affected mice developed paw inflammation at 4–8 weeks. Histological examinations revealed hyperplasia of the epidermis in the inflamed paws and increased macrophage expression in the spleen and paw tissues. Mechanical and thermal nociceptive response thresholds were reduced in the affected mice. Locomotor activity was decreased in affected mice with inflamed hindpaws, and this reduction was attributable to the avoidance of contact of the affected paw with the floor. Motor strength and daily activity in the home cage in the affected mice did not show any significant changes. Although Fos immunoreactivity was normal in the dorsal horn of affected mice, calcitonin gene-related peptide immunoreactivity significantly increased in the deep layer of the dorsal horn. The number of microglia increased in the spinal cord, hippocampus, and cerebral cortex in affected mice, and the proliferation of microglia was maintained for a couple of months. Two hundred eighty-five SNP markers were used to reveal the affected gene locus, which was found on the distal part of chromosome 18. A point mutation was detected at A to G in exon 8 of the pstpip2 gene, resulting in a conserved tyrosine residue at amino acid 180 replaced by cysteine (Y180 C. Conclusions The data provide definitive evidence that a mutation

New Mutations of Penicillin-Binding Proteins in Streptococcus agalactiae Isolates from Cattle with Decreased Susceptibility to Penicillin.

Science.gov (United States)

Hu, Yun; Kan, Yunchao; Zhang, Zhengtian; Lu, Zhanning; Li, Yanqiu; Leng, Chaoliang; Ji, Jun; Song, Shiyang; Shi, Hongfei

2018-02-23

Streptococcus agalactiae is a causal agent of bovine mastitis and is treated by β-lactam antibiotics (BLAs). Compared to penicillin-resistant S. agalactiae from humans, resistant strains in bovine are rarely reported. In this study, we aimed to investigate BLA resistance and mutations in penicillin-binding proteins (PBPs) of S. agalactiae in central and northeast China. The minimum inhibitory concentrations (MICs) of 129 penicillin-resistant S. agalactiae isolates from cows with mastitis were determined, and the related PBP genes were detected and sequenced. All strains were unsusceptible to penicillin G and mostly resistant to ampicillin, cefalexin, and ceftiofur sodium. One hundred twenty-nine strains were divided into 4 clonal groups and 8 sequence types by multilocus sequence typing analysis. We found a set of new substitutions in PBP1B, PBP2B, and PBP2X from most strains isolated from three provinces. The strains with high PBP mutations showed a broader unsusceptible spectrum and higher MICs than those with few or single mutation. Our research indicates unpredicted mutations in the PBP genes of S. agalactiae isolated from cows with mastitis treated by BLAs. This screening is the first of S. agalactiae from cattle.

Retinopathy of prematurity: mutations in the Norrie disease gene and the risk of progression to advanced stages.

Science.gov (United States)

Haider, M Z; Devarajan, L V; Al-Essa, M; Srivastva, B S; Kumar, H; Azad, R; Rashwan, N

2001-04-01

Retinopathy of prematurity (ROP) is a retinal vascular disease that occurs in infants with short gestational age and low birth weight and may lead to retinal detachment and blindness. Missense mutations in the Norrie disease (ND) gene have been associated with the risk of progression to advanced stages in cases of ROP from the US and also in clinically similar ND and familial exudative vitreoretinopathy. We have screened two ND gene mutations, namely A105T and Val60Glu, by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and allele-specific PCR methods, respectively, in 210 Kuwaiti premature newborns to replicate these findings in a different ethnic group. In the Kuwaiti premature newborn cohort, 115 of 210 babies had no eye problems and served as controls, while 95 were cases of ROP. In 71 of 95 ROP cases, the disease regressed spontaneously on or before stage 3, while in 24 of 95 ROP cases the disease progressed to advanced stages 4 and 5. In case of missense mutation (A105T), the AA genotype was detected in 96% of controls compared with 87% of ROP cases (NS); similarly no significant difference was found between spontaneously regressed ROP cases and those who progressed to advanced stages. For the Val60Glu mutation, no significant association was detected between the genotype and progression of ROP to advanced stages. Unlike data from the US, our findings from a Kuwaiti cohort of ROP cases and controls suggest a lack of association between the two ND gene mutations (A105T and Val60Glu) and ROP and the risk of progression of the disease to advanced stages.

X-ray-induced mutations in Escherichia coli K-12 strains with altered DNA polymerase I activities

International Nuclear Information System (INIS)

Nagata, Yuki; Kawata, Masakado; Komura, Jun-ichiro; Ono, Tetsuya; Yamamoto, Kazuo

2003-01-01

Spectra of ionizing radiation mutagenesis were determined by sequencing X-ray-induced endogenous tonB gene mutations in Escherichia coli polA strains. We used two polA alleles, the polA1 mutation, defective for Klenow domain, and the polA107 mutation, defective for flap domain. We demonstrated that irradiation of 75 and 50 Gy X-rays could induce 3.8- and 2.6-fold more of tonB mutation in polA1 and polA107 strains, respectively, than spontaneous level. The radiation induced spectrum of 51 tonB mutations in polA1 and 51 in polA107 indicated that minus frameshift, A:T→T:A transversion and G:C→T:A transversion were the types of mutations increased. Previously, we have reported essentially the same X-ray-induced tonB mutation spectra in the wild-type strain. These results indicate that (1) X-rays can induce minus frameshift, A:T→T:A transversion and G:C→T:A transversion in E. coli and (2) presence or absence of polymerase I (PolI) of E. coli does not have any effects on the process of X-ray mutagenesis

Lymphocytes from wasted mice express enhanced spontaneous and {gamma}-ray-induced apoptosis

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Woloschak, G.E. [Argonne National Lab., IL (United States)]|[Loyola Univ. Medical Center, Maywood, IL (United States); Chang-Liu, Chin-Mei [Argonne National Lab., IL (United States); Chung, Jen; Libertin, C.R. [Loyola Univ. Medical Center, Maywood, IL (United States)

1993-09-01

Mice bearing the autosomal recessive mutation wasted (wst/wst) display a disease pattern including faulty repair of DNA damage in lymphocytes after radiation exposure, neurologic abnormalities, and immunodeficiency. Many of the features of this mouse model have suggested a premature or increased spontaneous frequency of apoptosis in thymocytes; past work has shown an inability to establish cultured T cell lines, an abnormally high death rate of stimulated T cells in culture, and an increased sensitivity of T cells to the killing effects of ionizing radiations in wst/wst mice relative to controls. The experiments reported here were designed to examine splenic and thymic lymphocytes from wasted and control mice for signs of early apoptosis. Our results revealed enhanced expression of Rp-8 mRNA (associated with apoptosis) in thymic lymphocytes and reduced expression in splenic lymphocytes of wst/wst mice relative to controls; expression of Rp-2 and Td-30 mRNA (induced during apoptosis) were not detectable in spleen or thymus. Higher spontaneous DNA fragmentation was observed in wasted mice than in controls; however, {gamma}-ray-induced DNA fragmentation peaked at a lower dose and occurred to a greater extent in wasted mice relative to controls. These results provide evidence for high spontaneous and {gamma}-ray-induced apoptosis in T cells of wasted mice as a mechanism underlying the observed lymphocyte and DNA repair abnormalities.

The mutual dependence of M1 fertility and M2 mutations in rice

International Nuclear Information System (INIS)

Gopinathan Nair, V.

1982-01-01

The mutual dependence of M 1 fertility and M 2 mutations in rice was studied after treatment with gamma rays and EMS. The frequency of chlorophyll mutations increased with decrease in seed fertility when M 1 ears were selected at random. However, at the lowest fertility class the mutation frequency was low. This reduction is attributed to the elimination of mutants in the high sterility class. The mutation yield can therefore be significantly enhanced by selecting M 1 ears of low fertility. The segregation ratio of mutants increased as fertility decreased. Mutation spectrum was however not influenced by M 1 fertility. This makes selection for fertility quite ineffective in altering the mutation spectrum. (author)

Germline mutation rates in mice following in utero exposure to diesel exhaust particles by maternal inhalation

DEFF Research Database (Denmark)

Ritz, Caitlin; Ruminski, Wojciech; Hougaard, Karin S.

2011-01-01

(PAPs) from industrial environments cause DNA damage and mutations in the sperm of adult male mice. Effects on the female and male germline during critical stages of development (in utero) are unknown. In mice, previous studies have shown that expanded simple tandem repeat (ESTR) loci exhibit high rates......The induction of inherited DNA sequence mutations arising in the germline (i.e., sperm or egg) of mice exposed in utero to diesel exhaust particles (DEPs) via maternal inhalation compared to unexposed controls was investigated in this study. Previous work has shown that particulate air pollutants...... of spontaneous mutation, making this endpoint a valuable tool for studying inherited mutation and genomic instability. In the present study, pregnant C57Bl/6 mice were exposed to 19mg/m3 DEP from gestational day 7 through 19, alongside air exposed controls. Male and female F1 offspring were raised to maturity...

Distinguishing potential sources of genotoxic exposure via HPRT mutations

International Nuclear Information System (INIS)

Molholt, B.; Finette, B.A.

2000-01-01

T-cell HPRT (hypoxanthine phosphoribosyltransferase) mutations were used to monitor to environmental mutagens in children who have developed cancer at a persistently high rate in Toms River, New Jersey, USA. A preliminary epidemiological study has found a statistically-significant association between drinking public water (by pregnant mother or infant) and subsequent risk for childhood cancer. Three potential sources of mutagenic exposures in Toms River may have increased the rate of carcinogenic initiation significantly in children: 1. Benzidine-based, other azo-dye and anthraquinone dye wastes released by Ciba-Geigy enterprise; 2. Plastic wastes of Union Carbide enterprise; 3. Radium-224, present in unusually high concentrations in the Cohansey aquifer. Specific patterns of HPRT mutations are utilized to distinguish these various potential sources of carcinogenic exposures in the drinking water of families with childhood cancer and to differentiate chemically or radiologically induced cancers from those which occur spontaneously [ru

A mild mutator phenotype arises in a mouse model for malignancies associated with neurofibromatosis type 1

International Nuclear Information System (INIS)

Garza, Rene; Hudson, Robert A.; McMahan, C. Alex; Walter, Christi A.; Vogel, Kristine S.

2007-01-01

Defects in genes that control DNA repair, proliferation, and apoptosis can increase genomic instability, and thus promote malignant progression. Although most tumors that arise in humans with neurofibromatosis type 1 (NF1) are benign, these individuals are at increased risk for malignant peripheral nerve sheath tumors (MPNST). To characterize additional mutations required for the development of MPNST from benign plexiform neurofibromas, we generated a mouse model for these tumors by combining targeted null mutations in Nf1 and p53, in cis. CisNf1+/-; p53+/- mice spontaneously develop PNST, and these tumors exhibit loss-of-heterozygosity at both the Nf1 and p53 loci. Because p53 has well-characterized roles in the DNA damage response, DNA repair, and apoptosis, and because DNA repair genes have been proposed to act as modifiers in NF1, we used the cisNf1+/-; p53+/- mice to determine whether a mutator phenotype arises in NF1-associated malignancies. To quantitate spontaneous mutant frequencies (MF), we crossed the Big Blue mouse, which harbors a lacI transgene, to the cisNf1+/-; p53+/- mice, and isolated genomic DNA from both tumor and normal tissues in compound heterozygotes and wild-type siblings. Many of the PNST exhibited increased mutant frequencies (MF = 4.70) when compared to normal peripheral nerve and brain (MF = 2.09); mutations occurred throughout the entire lacI gene, and included base substitutions, insertions, and deletions. Moreover, the brains, spleens, and livers of these cisNf1+/-; p53+/- animals exhibited increased mutant frequencies when compared to tissues from wild-type littermates. We conclude that a mild mutator phenotype arises in the tumors and tissues of cisNf1+/-; p53+/- mice, and propose that genomic instability influences NF1 tumor progression and disease severity

Hypomorphic mutation in mouse Nppc gene causes retarded bone growth due to impaired endochondral ossification

International Nuclear Information System (INIS)

Tsuji, Takehito; Kondo, Eri; Yasoda, Akihiro; Inamoto, Masataka; Kiyosu, Chiyo; Nakao, Kazuwa; Kunieda, Tetsuo

2008-01-01

Long bone abnormality (lbab/lbab) is a spontaneous mutant mouse characterized by dwarfism with shorter long bones. A missense mutation was reported in the Nppc gene, which encodes C-type natriuretic peptide (CNP), but it has not been confirmed whether this mutation is responsible for the dwarf phenotype. To verify that the mutation causes the dwarfism of lbab/lbab mice, we first investigated the effect of CNP in lbab/lbab mice. By transgenic rescue with chondrocyte-specific expression of CNP, the dwarf phenotype in lbab/lbab mice was completely compensated. Next, we revealed that CNP derived from the lbab allele retained only slight activity to induce cGMP production through its receptor. Histological analysis showed that both proliferative and hypertrophic zones of chondrocytes in the growth plate of lbab/lbab mice were markedly reduced. Our results demonstrate that lbab/lbab mice have a hypomorphic mutation in the Nppc gene that is responsible for dwarfism caused by impaired endochondral ossification

Effect of Ku80 deficiency on mutation frequencies and spectra at a LacZ reporter locus in mouse tissues and cells.

Directory of Open Access Journals (Sweden)

Rita A Busuttil

Full Text Available Non-homologous end joining (NHEJ is thought to be an important mechanism for preventing the adverse effects of DNA double strand breaks (DSBs and its absence has been associated with premature aging. To investigate the effect of inactivated NHEJ on spontaneous mutation frequencies and spectra in vivo and in cultured cells, we crossed a Ku80-deficient mouse with mice harboring a lacZ-plasmid-based mutation reporter. We analyzed various organs and tissues, as well as cultured embryonic fibroblasts, for mutations at the lacZ locus. When comparing mutant with wild-type mice, we observed a significantly higher number of genome rearrangements in liver and spleen and a significantly lower number of point mutations in liver and brain. The reduced point mutation frequency was not due to a decrease in small deletion mutations thought to be a hallmark of NHEJ, but could be a consequence of increased cellular responses to unrepaired DSBs. Indeed, we found a substantial increase in persistent 53BP1 and gammaH2AX DNA damage foci in Ku80-/- as compared to wild-type liver. Treatment of cultured Ku80-deficient or wild-type embryonic fibroblasts, either proliferating or quiescent, with hydrogen peroxide or bleomycin showed no differences in the number or type of induced genome rearrangements. However, after such treatment, Ku80-deficient cells did show an increased number of persistent DNA damage foci. These results indicate that Ku80-dependent repair of DNA damage is predominantly error-free with the effect of alternative more error-prone pathways creating genome rearrangements only detectable after extended periods of time, i.e., in young adult animals. The observed premature aging likely results from a combination of increased cellular senescence and an increased load of stable, genome rearrangements.

Evolutionary pattern of mutation in the factor IX genes of great apes: How does it compare to the pattern of recent germline mutation in patients with hemophilia B?

Energy Technology Data Exchange (ETDEWEB)

Grouse, L.H.; Ketterling, R.P.; Sommer, S.S. [Mayo Clinic/Foundation, Rochester, MN (United States)

1994-09-01

Most mutations causing hemophilia B have arisen within the past 150 years. By correcting for multiple biases, the underlying rates of spontaneous germline mutation have been estimated in the factor IX gene. From these rates, an underlying pattern of mutation has emerged. To determine if this pattern compares to a underlying pattern found in the great apes, sequence changes were determined in intronic regions of the factor IX gene. The following species were studied: Gorilla gorilla, Pan troglodytes (chimpanzee), Pongo pygmacus (orangutan) and Homo sapiens. Intronic sequences at least 200 bp from a splice junction were randomly chosen, amplified by cross-species PCR, and sequenced. These regions are expected to be subject to little if any selective pressure. Early diverged species of Old World monkeys were also studied to help determine the direction of mutational changes. A total of 62 sequence changes were observed. Initial data suggest that the average pattern since evolution of the great apes has a paucity of transitions at CpG dinucleotides and an excess of microinsertions to microdeletions when compared to the pattern observed in humans during the past 150 years (p<.05). A larger study is in progress to confirm these results.

Quantitative and molecular analyses of mutation in a pSV2gpt transformed CHO cell line

International Nuclear Information System (INIS)

Stankowski, L.F. Jr.; Tindall, K.R.; Hsie, A.W.

1983-01-01

Following NDA-mediated gene transfer we have isolated a cell line useful for studying gene mutation at the molecular level. This line, AS52, derived from a hypoxanthine-guanine phosphoribosyl transferase (HGPRT) deficient Chinese hamster ovary (CHO) cell line, carries a single copy of the E. coli xanthine-guanine phosphoribosyl transferase (XGPRT) gene (gpt) and exhibits a spontaneous mutant frequency of 20 TG/sup r/ mutants/10 6 clonable cells. As with HGPRT - mutants, XGPRT - mutants can be selected in 6-thioguanine. AS52 (XGPRT + ) and wild type CHO (HGPRT + ) cell exhibit almost identical cytotoxic responses to various agents. We observed significant differences in mutation induction by UV light and ethyl methanesulfonate (EMS). Ratios of XGPRT - to HGPRT - mutants induced per unit dose (J/m 2 for UV light and μg/ml for EMS) are 1.4 and 0.70, respectively. Preliminary Southern blot hybridization analyses has been performed on 30 XGPRT - AS52 mutants. A majority of spontaneous mutants have deletions ranging in size from 1 to 4 kilobases (9/19) to complete loss of gpt sequences (4/19); the remainder have no detectable (5/19) or only minor (1/19) alterations. 5/5 UV-induced and 5/6 EMS-induced mutants do not show a detectable change. Similar analyses are underway for mutations induced by x-irradiation and ICR 191 treatment

Characterization of phospholipase C gamma enzymes with gain-of-function mutations.

Science.gov (United States)

Everett, Katy L; Bunney, Tom D; Yoon, Youngdae; Rodrigues-Lima, Fernando; Harris, Richard; Driscoll, Paul C; Abe, Koichiro; Fuchs, Helmut; de Angelis, Martin Hrabé; Yu, Philipp; Cho, Wohnwa; Katan, Matilda

2009-08-21

Phospholipase C gamma isozymes (PLC gamma 1 and PLC gamma 2) have a crucial role in the regulation of a variety of cellular functions. Both enzymes have also been implicated in signaling events underlying aberrant cellular responses. Using N-ethyl-N-nitrosourea (ENU) mutagenesis, we have recently identified single point mutations in murine PLC gamma 2 that lead to spontaneous inflammation and autoimmunity. Here we describe further, mechanistic characterization of two gain-of-function mutations, D993G and Y495C, designated as ALI5 and ALI14. The residue Asp-993, mutated in ALI5, is a conserved residue in the catalytic domain of PLC enzymes. Analysis of PLC gamma 1 and PLC gamma 2 with point mutations of this residue showed that removal of the negative charge enhanced PLC activity in response to EGF stimulation or activation by Rac. Measurements of PLC activity in vitro and analysis of membrane binding have suggested that ALI5-type mutations facilitate membrane interactions without compromising substrate binding and hydrolysis. The residue mutated in ALI14 (Tyr-495) is within the spPH domain. Replacement of this residue had no effect on folding of the domain and enhanced Rac activation of PLC gamma 2 without increasing Rac binding. Importantly, the activation of the ALI14-PLC gamma 2 and corresponding PLC gamma 1 variants was enhanced in response to EGF stimulation and bypassed the requirement for phosphorylation of critical tyrosine residues. ALI5- and ALI14-type mutations affected basal activity only slightly; however, their combination resulted in a constitutively active PLC. Based on these data, we suggest that each mutation could compromise auto-inhibition in the inactive PLC, facilitating the activation process; in addition, ALI5-type mutations could enhance membrane interaction in the activated state.

GFI1B mutation causes a bleeding disorder with abnormal platelet function.

Science.gov (United States)

Stevenson, W S; Morel-Kopp, M-C; Chen, Q; Liang, H P; Bromhead, C J; Wright, S; Turakulov, R; Ng, A P; Roberts, A W; Bahlo, M; Ward, C M

2013-11-01

GFI1B is a transcription factor important for erythropoiesis and megakaryocyte development but previously unknown to be associated with human disease. A family with a novel bleeding disorder was identified and characterized. Genetic linkage analysis and massively parallel sequencing were used to localize the mutation causing the disease phenotype on chromosome 9. Functional studies were then performed in megakaryocytic cell lines to determine the biological effects of the mutant transcript. We have identified a family with an autosomal dominant bleeding disorder associated with macrothrombocytopenia, red cell anisopoikilocytosis, and platelet dysfunction. The severity of bleeding is variable with some affected individuals experiencing spontaneous bleeding while other family members exhibit only abnormal bleeding with surgery. A single nucleotide insertion was identified in GFI1B that predicts a frameshift mutation in the fifth zinc finger DNA-binding domain. This mutation alters the transcriptional activity of the protein, resulting in a reduction in platelet α-granule content and aberrant expression of key platelet proteins. GFI1B mutation represents a novel human bleeding disorder, and the described phenotype identifies GFI1B as a critical regulator of platelet shape, number, and function. © 2013 International Society on Thrombosis and Haemostasis.

Gamma oscillations and spontaneous network activity in the hippocampus are highly sensitive to decreases in pO2 and concomitant changes in mitochondrial redox state.

Science.gov (United States)

Huchzermeyer, Christine; Albus, Klaus; Gabriel, Hans-Jürgen; Otáhal, Jakub; Taubenberger, Nando; Heinemann, Uwe; Kovács, Richard; Kann, Oliver

2008-01-30

Gamma oscillations have been implicated in higher cognitive processes and might critically depend on proper mitochondrial function. Using electrophysiology, oxygen sensor microelectrode, and imaging techniques, we investigated the interactions of neuronal activity, interstitial pO2, and mitochondrial redox state [NAD(P)H and FAD (flavin adenine dinucleotide) fluorescence] in the CA3 subfield of organotypic hippocampal slice cultures. We find that gamma oscillations and spontaneous network activity decrease significantly at pO2 levels that do not affect neuronal population responses as elicited by moderate electrical stimuli. Moreover, pO2 and mitochondrial redox states are tightly coupled, and electrical stimuli reveal transient alterations of redox responses when pO2 decreases within the normoxic range. Finally, evoked redox responses are distinct in somatic and synaptic neuronal compartments and show different sensitivity to changes in pO2. We conclude that the threshold of interstitial pO2 for robust CA3 network activities and required mitochondrial function is clearly above the "critical" value, which causes spreading depression as a result of generalized energy failure. Our study highlights the importance of a functional understanding of mitochondria and their implications on activities of individual neurons and neuronal networks.

Radionuclide cisternographic findings in patients with spontaneous intracranial hypotension

International Nuclear Information System (INIS)

Jung, Dong Jin; Kim, Jae Seung; Ryu, Jin Sook; Shin, Jung Woo; Im, Joo Hyuk; Lee, Myoung Chong; Jung, Sung Joo; Moon, Dae Hyuk; Lee, Hee Kyung

1998-01-01

Radionuclide cisternography may be helpful in understanding pathophysiology of postural headache and low CSF pressure in patients with spontaneous intracranial hypotension. The purpose of this study was to characterize radionuclide cisternogrpahic findings of spontaneous intracranial hypotension. The study population consists of 15 patients with spontaneous intracranial hypotension. Diagnosis was based on their clinical symptoms and results of lumbar puncture. All patients underwent radionuclide cisternography following injection of 111 to 222 MBq of Tc-99m DTPA into the lumbar subarachnoid space. Sequential images were obtained between 1/2 hour and 24 hour after the injection of Tc-99m DTPA. Radioactivity of the bladder, soft tissue uptake, migration of radionuclide in the subarachnoid space, and extradural leakage of radionuclide were evaluated according to the scan time. Radionuclide cisternogram showed delayed migration of radionuclide into the cerebral convexity (14/15), increased soft tissue uptake (11/15), and early visualization of bladder activity at 30 min (6/10) and 2 hr (13/13). Cisternography also demonstrated leakage site of CSF in 4 cases and 2 of these were depicted at 30min. Epidural blood patch was done in 11 patients and headache was improved in all cases. The characteristics findings of spontaneous intracranial hypotension were delayed migration of radionuclide and early visualization of the soft tissue and bladder activity. These scintigraphic findings suggest that CSF leakage rather than increased CSF absorption or decreased production may be the main pathophysiology of spontaneous intracranial hypotension. Early and multiple imaging including the bladder and soft tissue is required to observe the entire dynamics of radionuclide migration

Spontaneous coronary artery dissection and its association with heritable connective tissue disorders.

Science.gov (United States)

Henkin, Stanislav; Negrotto, Sara M; Tweet, Marysia S; Kirmani, Salman; Deyle, David R; Gulati, Rajiv; Olson, Timothy M; Hayes, Sharonne N

2016-06-01

Spontaneous coronary artery dissection (SCAD) is an under-recognised but important cause of myocardial infarction and sudden cardiac death. We sought to determine the role of medical and molecular genetic screening for connective tissue disorders in patients with SCAD. We performed a single-centre retrospective descriptive analysis of patients with spontaneous coronary artery disease who had undergone medical genetics evaluation 1984-2014 (n=116). The presence or absence of traits suggestive of heritable connective tissue disease was extracted. Genetic testing for connective tissue disorders and/or aortopathies, if performed, is also reported. Of the 116 patients (mean age 44.2 years, 94.8% women and 41.4% with non-coronary fibromuscular dysplasia (FMD)), 59 patients underwent genetic testing, of whom 3 (5.1%) received a diagnosis of connective tissue disorder: a 50-year-old man with Marfan syndrome; a 43-year-old woman with vascular Ehlers-Danlos syndrome and FMD; and a 45-year-old woman with vascular Ehlers-Danlos syndrome. An additional 12 patients (20.3%) had variants of unknown significance, none of which was thought to be a definite disease-causing mutation based on in silico analyses. Only a minority of patients with SCAD who undergo genetic evaluation have a likely pathogenic mutation identified on gene panel testing. Even fewer exhibit clinical features of connective tissue disorder. These findings underscore the need for further studies to elucidate the molecular mechanisms of SCAD. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Spontaneous germline excision of Tol1, a DNA-based transposable element naturally occurring in the medaka fish genome.

Science.gov (United States)

Watanabe, Kohei; Koga, Hajime; Nakamura, Kodai; Fujita, Akiko; Hattori, Akimasa; Matsuda, Masaru; Koga, Akihiko

2014-04-01

DNA-based transposable elements are ubiquitous constituents of eukaryotic genomes. Vertebrates are, however, exceptional in that most of their DNA-based elements appear to be inactivated. The Tol1 element of the medaka fish, Oryzias latipes, is one of the few elements for which copies containing an undamaged gene have been found. Spontaneous transposition of this element in somatic cells has previously been demonstrated, but there is only indirect evidence for its germline transposition. Here, we show direct evidence of spontaneous excision in the germline. Tyrosinase is the key enzyme in melanin biosynthesis. In an albino laboratory strain of medaka fish, which is homozygous for a mutant tyrosinase gene in which a Tol1 copy is inserted, we identified de novo reversion mutations related to melanin pigmentation. The gamete-based reversion rate was as high as 0.4%. The revertant fish carried the tyrosinase gene from which the Tol1 copy had been excised. We previously reported the germline transposition of Tol2, another DNA-based element that is thought to be a recent invader of the medaka fish genome. Tol1 is an ancient resident of the genome. Our results indicate that even an old element can contribute to genetic variation in the host genome as a natural mutator.

The second activating glucokinase mutation (A456V)

DEFF Research Database (Denmark)

Christesen, Henrik B T; Jacobsen, Bendt B; Odili, Stella

2002-01-01

for mutations in candidate genes revealed a heterozygous glucokinase mutation in exon 10, substituting valine for alanine at codon 456 (A456V) in the proband and his mother. The purified recombinant glutathionyl S-transferase fusion protein of the A456V glucokinase revealed a decreased glucose S(0.5) (the...

Spontaneous external gallbladder perforation

International Nuclear Information System (INIS)

Noeldge, G.; Wimmer, B.; Kirchner, R.

1981-01-01

Spontaneous perforation of the gallbladder is one complication of cholelithiasis. There is a greater occurence of free perforation in the peritoneal cavity with bilary pertonitis, followed by the perforation into the stomach, small intestine and colon. A single case of the nowadays rare spontaneous perforation in and through the abdominal wall will be reported. Spontaneous gallbladder perforation appears nearly asymptomatic in its clinical course because of absent biliary peritonitis. (orig.) [de

Analysis of mutations in the human HPRT gene induced by accelerated heavy-ion irradiation

International Nuclear Information System (INIS)

Kagawa, Yasuhiro; Yatagai, Fumio; Hanaoka, Fumio; Suzuki, Masao; Kase, Youko; Kobayashi, Akiko; Hirano, Masahiko; Kato, Takesi; Watanabe, Masami.

1995-01-01

Multiplex PCR analysis of HPRT(-) mutations in human embryo (HE) cells induced by 230 keV/μm carbon-ion irradiation showed no large deletion around the exon regions of the locus gene in contrast to the irradiations at different LETs. To identify these mutations, the sequence alterations in a cDNA of hprt gene were determined for 18 mutant clones in this study. Missing of exon 6 was the most frequent mutational event (10 clones), and missing of both exons 6 and 8 was next most frequent event (6 clones), then base substitutions (2 clones). These characteristics were not seen in a similar analysis of spontaneous mutations, which showed base substitution (5 clones), frameshift (2 clones), missing of both exons 2 and 3 (2 clones), and a single unidentified clone. Direct sequencing and restriction enzyme digestion of the genomic DNA of the mutants which showed missing of exons 6 and 8 in the cDNA, supports the possibility that they were induced by aberrant mRNA splicing. (author)

Spontaneous regression of intracranial malignant lymphoma

International Nuclear Information System (INIS)

Kojo, Nobuto; Tokutomi, Takashi; Eguchi, Gihachirou; Takagi, Shigeyuki; Matsumoto, Tomie; Sasaguri, Yasuyuki; Shigemori, Minoru.

1988-01-01

In a 46-year-old female with a 1-month history of gait and speech disturbances, computed tomography (CT) demonstrated mass lesions of slightly high density in the left basal ganglia and left frontal lobe. The lesions were markedly enhanced by contrast medium. The patient received no specific treatment, but her clinical manifestations gradually abated and the lesions decreased in size. Five months after her initial examination, the lesions were absent on CT scans; only a small area of low density remained. Residual clinical symptoms included mild right hemiparesis and aphasia. After 14 months the patient again deteriorated, and a CT scan revealed mass lesions in the right frontal lobe and the pons. However, no enhancement was observed in the previously affected regions. A biopsy revealed malignant lymphoma. Despite treatment with steroids and radiation, the patient's clinical status progressively worsened and she died 27 months after initial presentation. Seven other cases of spontaneous regression of primary malignant lymphoma have been reported. In this case, the mechanism of the spontaneous regression was not clear, but changes in immunologic status may have been involved. (author)

Definition of spontaneous reconnection

International Nuclear Information System (INIS)

Schindler, K.

1984-01-01

The author discusses his view of driven versus spontaneous. There is a close link between ''spontaneous'' and ''instability.'' One of the prominent examples for instability is the thermal convection instability. Just to remind you, if you heat a fluid layer from below, it takes a certain Rayleigh number to make it unstable. Beyond the onset point you find qualitatively new features. That is called ''spontaneous,'' and this is a bit more than semantics. It's a new qualitative property that appears and it is spontaneous although we have an energy flux through the system. It's a misconception, to call this ''driven'' pointing at the energy flux through it. Of course, the convection would not exist without this energy flux. But what makes it ''spontaneous'' is that without any particular external signal, a new qualitative feature appears. And this is what is called an ''instability'' and ''spontaneous.'' From these considerations the author got a little reassured of what distinction should be made in the field of the magnetosphere. If we have a smooth energy transport into the magnetosphere and suddenly we have this qualitatively new feature (change of B-topology) coming up; then, using this terminology we don't have a choice other than calling this spontaneous or unstable, if you like. If we ''tell'' the system where it should make its neutral line and where it should make its plasmoids, then, it is driven. And this provides a very clear-cut observational distinction. The author emphasizes the difference he sees is a qualitative difference, not only a quantitative one

Acute Abdomen Due to Uncontrolled Use of Warfarin: Spontaneous Intra-abdominal

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Fatih Dal

2017-12-01

Full Text Available Warfarin is an oral anticoagulant, which is commonly used in the treatment and prophylaxis of thromboembolic conditions. Bleeding is the primary adverse effect associated with warfarin. The majority of warfarin-related bleedings are spontaneous minor hemorrhages occurring in the subcutaneous or intramuscular tissues and can be treated by decreasing the dose of oral anticoagulants. However, although rare, it is possible to encounter spontaneous major bleedings with increased risk of mortality. Conservative approach is the preferred initial therapy for hemodynamically stable patients with major intra-abdominal hemorrhages that we define as the intermediate group patients. Nevertheless, surgery is required for hemodynamically unstable patients with acute abdominal pain in cases of ongoing active hemorrhage, generalized peritonitis, obstruction, acute abdomen, intestinal ischemia, and perforation. In this article, we present a rare case of acute abdomen and spontaneous intra-abdominal hemorrhage resulting from uncontrolled use of warfarin and a new classification requirement.

Different responses of spontaneous and stimulus-related alpha activity to ambient luminance changes.

Science.gov (United States)

Benedetto, Alessandro; Lozano-Soldevilla, Diego; VanRullen, Rufin

2017-12-04

Alpha oscillations are particularly important in determining our percepts and have been implicated in fundamental brain functions. Oscillatory activity can be spontaneous or stimulus-related. Furthermore, stimulus-related responses can be phase- or non-phase-locked to the stimulus. Non-phase-locked (induced) activity can be identified as the average amplitude changes in response to a stimulation, while phase-locked activity can be measured via reverse-correlation techniques (echo function). However, the mechanisms and the functional roles of these oscillations are far from clear. Here, we investigated the effect of ambient luminance changes, known to dramatically modulate neural oscillations, on spontaneous and stimulus-related alpha. We investigated the effect of ambient luminance on EEG alpha during spontaneous human brain activity at rest (experiment 1) and during visual stimulation (experiment 2). Results show that spontaneous alpha amplitude increased by decreasing ambient luminance, while alpha frequency remained unaffected. In the second experiment, we found that under low-luminance viewing, the stimulus-related alpha amplitude was lower, and its frequency was slightly faster. These effects were evident in the phase-locked part of the alpha response (echo function), but weaker or absent in the induced (non-phase-locked) alpha responses. Finally, we explored the possible behavioural correlates of these modulations in a monocular critical flicker frequency task (experiment 3), finding that dark adaptation in the left eye decreased the temporal threshold of the right eye. Overall, we found that ambient luminance changes impact differently on spontaneous and stimulus-related alpha expression. We suggest that stimulus-related alpha activity is crucial in determining human temporal segmentation abilities. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Spontaneous Colon Perforations Associated with a Vascular Type of Ehlers-Danlos Syndrome

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Akira Yoneda

2014-05-01

Full Text Available Ehlers-Danlos syndrome, vascular type (vEDS (MIM #130050 is an autosomal dominant disorder caused by mutation in the type III collagen gene, COL3A1, leading to fragility of blood vessels, bowel and uterus that leads to spontaneous rupture. We report a previously undiagnosed vEDS patient with bowel complications. A 20-year-old female patient was referred to our hospital with abdominal pain. Computed tomography showed notable dilatation of the sigmoid colon with intraperitoneal fluid. Laparotomy revealed dilatation of the sigmoid colon, breakdown of serosa and muscularis propria of the sigmoid colon with impending perforation, and intra-abdominal hemorrhage caused by breakdown of the mesenterium. Resection of the sigmoid colon with Hartmann's pouch and an end colostomy were performed. Physical examination showed joint hypermobility, translucent skin with venous prominence and facial structure abnormalities. Genetic analysis using cDNA extracted from the patient's fibroblasts by reverse transcriptase polymerase chain reaction direct sequencing showed a missense mutation within the triple helix region of COL3A1 (c.2150 G>A; Gly717Asp.

THE ANTIMUTAGENIC EFFECT OF VANILLIN AND CINNAMALDEHYDE ON SPONTANEOUS MUTATION IN SALMONELLA TA104 IS DUE TO A REDUCTION IN MUTATIONS AT GC BUT NOT AT SITES

Science.gov (United States)

Abstract Vanillin (VAN) and cinnamaldehyde (CIN) are dietary antimutagens that, when added to assay plates, reduced the spontaneous mutant frequency in Salmonella typhimurium strain TA104 (hisG428, rfa, uvrB, pKM101) by 50%. To date, no study has demonstrated whether or not...

Genetic screening of the FLCN gene identify six novel variants and a Danish founder mutation

DEFF Research Database (Denmark)

Rossing, Maria; Albrechtsen, Anders; Skytte, Anne-Bine

2016-01-01

Pathogenic germline mutations in the folliculin (FLCN) tumor suppressor gene predispose to Birt-Hogg-Dubé (BHD) syndrome, a rare disease characterized by the development of cutaneous hamartomas (fibrofolliculomas), multiple lung cysts, spontaneous pneumothoraces and renal cell cancer. In this stu...... understanding of BHD syndrome and management of BHD patients.Journal of Human Genetics advance online publication, 13 October 2016; doi:10.1038/jhg.2016.118....

The Rate and Spectrum of Spontaneous Mutations in Mycobacterium smegmatis, a Bacterium Naturally Devoid of the Postreplicative Mismatch Repair Pathway.

Science.gov (United States)

Kucukyildirim, Sibel; Long, Hongan; Sung, Way; Miller, Samuel F; Doak, Thomas G; Lynch, Michael

2016-07-07

Mycobacterium smegmatis is a bacterium that is naturally devoid of known postreplicative DNA mismatch repair (MMR) homologs, mutS and mutL, providing an opportunity to investigate how the mutation rate and spectrum has evolved in the absence of a highly conserved primary repair pathway. Mutation accumulation experiments of M. smegmatis yielded a base-substitution mutation rate of 5.27 × 10(-10) per site per generation, or 0.0036 per genome per generation, which is surprisingly similar to the mutation rate in MMR-functional unicellular organisms. Transitions were found more frequently than transversions, with the A:T→G:C transition rate significantly higher than the G:C→A:T transition rate, opposite to what is observed in most studied bacteria. We also found that the transition-mutation rate of M. smegmatis is significantly lower than that of other naturally MMR-devoid or MMR-knockout organisms. Two possible candidates that could be responsible for maintaining high DNA fidelity in this MMR-deficient organism are the ancestral-like DNA polymerase DnaE1, which contains a highly efficient DNA proofreading histidinol phosphatase (PHP) domain, and/or the existence of a uracil-DNA glycosylase B (UdgB) homolog that might protect the GC-rich M. smegmatis genome against DNA damage arising from oxidation or deamination. Our results suggest that M. smegmatis has a noncanonical Dam (DNA adenine methylase) methylation system, with target motifs differing from those previously reported. The mutation features of M. smegmatis provide further evidence that genomes harbor alternative routes for improving replication fidelity, even in the absence of major repair pathways. Copyright © 2016 Kucukyildirim et al.

The Rate and Spectrum of Spontaneous Mutations in Mycobacterium smegmatis, a Bacterium Naturally Devoid of the Postreplicative Mismatch Repair Pathway

Directory of Open Access Journals (Sweden)

Sibel Kucukyildirim

2016-07-01

Full Text Available Mycobacterium smegmatis is a bacterium that is naturally devoid of known postreplicative DNA mismatch repair (MMR homologs, mutS and mutL, providing an opportunity to investigate how the mutation rate and spectrum has evolved in the absence of a highly conserved primary repair pathway. Mutation accumulation experiments of M. smegmatis yielded a base-substitution mutation rate of 5.27 × 10−10 per site per generation, or 0.0036 per genome per generation, which is surprisingly similar to the mutation rate in MMR-functional unicellular organisms. Transitions were found more frequently than transversions, with the A:T→G:C transition rate significantly higher than the G:C→A:T transition rate, opposite to what is observed in most studied bacteria. We also found that the transition-mutation rate of M. smegmatis is significantly lower than that of other naturally MMR-devoid or MMR-knockout organisms. Two possible candidates that could be responsible for maintaining high DNA fidelity in this MMR-deficient organism are the ancestral-like DNA polymerase DnaE1, which contains a highly efficient DNA proofreading histidinol phosphatase (PHP domain, and/or the existence of a uracil-DNA glycosylase B (UdgB homolog that might protect the GC-rich M. smegmatis genome against DNA damage arising from oxidation or deamination. Our results suggest that M. smegmatis has a noncanonical Dam (DNA adenine methylase methylation system, with target motifs differing from those previously reported. The mutation features of M. smegmatis provide further evidence that genomes harbor alternative routes for improving replication fidelity, even in the absence of major repair pathways.

Hypomyelinating leukodystrophy-associated missense mutation in HSPD1 blunts mitochondrial dynamics

Energy Technology Data Exchange (ETDEWEB)

Miyamoto, Yuki [Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535 (Japan); Eguchi, Takahiro [The Institute of Medical Science, The University of Tokyo, Minato, Tokyo 108-8639 (Japan); Kawahara, Kazuko [Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535 (Japan); Hasegawa, Nanami [Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535 (Japan); Faculty of Pharmacy, Keio University, Minato, Tokyo 105-8512 (Japan); Nakamura, Kazuaki [Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535 (Japan); Funakoshi-Tago, Megumi [Faculty of Pharmacy, Keio University, Minato, Tokyo 105-8512 (Japan); Tanoue, Akito [Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535 (Japan); Tamura, Hiroomi [Faculty of Pharmacy, Keio University, Minato, Tokyo 105-8512 (Japan); Yamauchi, Junji, E-mail: yamauchi-j@ncchd.go.jp [Department of Pharmacology, National Research Institute for Child Health and Development, Setagaya, Tokyo 157-8535 (Japan); Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Bunkyo, Tokyo 113-8510 (Japan)

2015-07-03

Myelin-forming glial cells undergo dynamic morphological changes in order to produce mature myelin sheaths with multiple layers. In the central nervous system (CNS), oligodendrocytes differentiate to insulate neuronal axons with myelin sheaths. Myelin sheaths play a key role in homeostasis of the nervous system, but their related disorders lead not only to dismyelination and repeated demyelination but also to severe neuropathies. Hereditary hypomyelinating leukodystrophies (HLDs) are a group of such diseases affecting oligodendrocytes and are often caused by missense mutations of the respective responsible genes. Despite increasing identification of gene mutations through advanced nucleotide sequencing technology, studies on the relationships between gene mutations and their effects on cellular and subcellular aberrance have not followed at the same rapid pace. In this study, we report that an HLD4-associated (Asp-29-to-Gly) mutant of mitochondrial heat shock 60-kDa protein 1 (HSPD1) causes short-length morphologies and increases the numbers of mitochondria due to their aberrant fission and fusion cycles. In experiments using a fluorescent dye probe, this mutation decreases the mitochondrial membrane potential. Also, mitochondria accumulate in perinuclear regions. HLD4-associated HSPD1 mutant blunts mitochondrial dynamics, probably resulting in oligodendrocyte malfunction. This study constitutes a first finding concerning the relationship between disease-associated HSPD1 mutation and mitochondrial dynamics, which may be similar to the relationship between another disease-associated HSPD1 mutation (MitCHAP-60 disease) and aberrant mitochondrial dynamics. - Highlights: • The HLD4 mutant of HSPD1 decreases mitochondrial fission frequency. • The HLD4 mutant decreases mitochondrial fusion frequency. • Mitochondria harboring the HLD4 mutant exhibit slow motility. • The HLD4 mutant of HSPD1 decreases mitochondrial membrane potential. • HLD4-related diseases may

Hypomyelinating leukodystrophy-associated missense mutation in HSPD1 blunts mitochondrial dynamics

International Nuclear Information System (INIS)

Miyamoto, Yuki; Eguchi, Takahiro; Kawahara, Kazuko; Hasegawa, Nanami; Nakamura, Kazuaki; Funakoshi-Tago, Megumi; Tanoue, Akito; Tamura, Hiroomi; Yamauchi, Junji

2015-01-01

Myelin-forming glial cells undergo dynamic morphological changes in order to produce mature myelin sheaths with multiple layers. In the central nervous system (CNS), oligodendrocytes differentiate to insulate neuronal axons with myelin sheaths. Myelin sheaths play a key role in homeostasis of the nervous system, but their related disorders lead not only to dismyelination and repeated demyelination but also to severe neuropathies. Hereditary hypomyelinating leukodystrophies (HLDs) are a group of such diseases affecting oligodendrocytes and are often caused by missense mutations of the respective responsible genes. Despite increasing identification of gene mutations through advanced nucleotide sequencing technology, studies on the relationships between gene mutations and their effects on cellular and subcellular aberrance have not followed at the same rapid pace. In this study, we report that an HLD4-associated (Asp-29-to-Gly) mutant of mitochondrial heat shock 60-kDa protein 1 (HSPD1) causes short-length morphologies and increases the numbers of mitochondria due to their aberrant fission and fusion cycles. In experiments using a fluorescent dye probe, this mutation decreases the mitochondrial membrane potential. Also, mitochondria accumulate in perinuclear regions. HLD4-associated HSPD1 mutant blunts mitochondrial dynamics, probably resulting in oligodendrocyte malfunction. This study constitutes a first finding concerning the relationship between disease-associated HSPD1 mutation and mitochondrial dynamics, which may be similar to the relationship between another disease-associated HSPD1 mutation (MitCHAP-60 disease) and aberrant mitochondrial dynamics. - Highlights: • The HLD4 mutant of HSPD1 decreases mitochondrial fission frequency. • The HLD4 mutant decreases mitochondrial fusion frequency. • Mitochondria harboring the HLD4 mutant exhibit slow motility. • The HLD4 mutant of HSPD1 decreases mitochondrial membrane potential. • HLD4-related diseases may

Xeroderma Pigmentosum-Trichothiodystrophy overlap patient with novel XPD/ERCC2 mutation

DEFF Research Database (Denmark)

Kralund, Henrik H; Ousager, Lilian; Jaspers, Nicolaas G

2013-01-01

outcome from many of these mutations. We demonstrate a patient, believed to represent an overlap between XP and TTD/CS. In addition to other organ dysfunctions, the young man presented with Photosensitivity, Ichthyosis, Brittle hair, Impaired physical and mental development, Decreased fertility and Short...... appearance also suggested XP, but fibroblast cultures only demonstrated x2 UV-sensitivity with expected NER and TFIIH-activity decrease. Genetic sequencing of the XPD/ERCC2 gene established the patient as heterozygote compound with a novel, N-terminal Y18H mutation and a known C-terminal (TTD) mutation, A725...

Reduced Mutation Rate and Increased Transformability of Transposon-Free Acinetobacter baylyi ADP1-ISx.

Science.gov (United States)

Suárez, Gabriel A; Renda, Brian A; Dasgupta, Aurko; Barrick, Jeffrey E

2017-09-01

The genomes of most bacteria contain mobile DNA elements that can contribute to undesirable genetic instability in engineered cells. In particular, transposable insertion sequence (IS) elements can rapidly inactivate genes that are important for a designed function. We deleted all six copies of IS 1236 from the genome of the naturally transformable bacterium Acinetobacter baylyi ADP1. The natural competence of ADP1 made it possible to rapidly repair deleterious point mutations that arose during strain construction. In the resulting ADP1-ISx strain, the rates of mutations inactivating a reporter gene were reduced by 7- to 21-fold. This reduction was higher than expected from the incidence of new IS 1236 insertions found during a 300-day mutation accumulation experiment with wild-type ADP1 that was used to estimate spontaneous mutation rates in the strain. The extra improvement appears to be due in part to eliminating large deletions caused by IS 1236 activity, as the point mutation rate was unchanged in ADP1-ISx. Deletion of an error-prone polymerase ( dinP ) and a DNA damage response regulator ( umuD Ab [the umuD gene of A. baylyi ]) from the ADP1-ISx genome did not further reduce mutation rates. Surprisingly, ADP1-ISx exhibited increased transformability. This improvement may be due to less autolysis and aggregation of the engineered cells than of the wild type. Thus, deleting IS elements from the ADP1 genome led to a greater than expected increase in evolutionary reliability and unexpectedly enhanced other key strain properties, as has been observed for other clean-genome bacterial strains. ADP1-ISx is an improved chassis for metabolic engineering and other applications. IMPORTANCE Acinetobacter baylyi ADP1 has been proposed as a next-generation bacterial host for synthetic biology and genome engineering due to its ability to efficiently take up DNA from its environment during normal growth. We deleted transposable elements that are capable of copying themselves

A new Gsdma3 mutation affecting anagen phase of first hair cycle

International Nuclear Information System (INIS)

Tanaka, Shigekazu; Tamura, Masaru; Aoki, Aya; Fujii, Tomoaki; Komiyama, Hiromitsu; Sagai, Tomoko; Shiroishi, Toshihiko

2007-01-01

Recombination-induced mutation 3 (Rim3) is a spontaneous mouse mutation that exhibits dominant phenotype of hyperkeratosis and hair loss. Fine linkage analysis of Rim3 and sequencing revealed a novel single point mutation, G1124A leading to Ala348Thr, in Gsdma3 in chromosome 11. Transgenesis with BAC DNA harboring the Rim3-type Gsdma3 recaptured the Rim3 phenotype, providing direct evidence that Gsdma3 is the causative gene of Rim3. We examined the spatial expression of Gsdma3 and characterized the Rim3 phenotype in detail. Gsdma3 is expressed in differentiated epidermal cells in the skin, but not in the proliferating epidermal cells. Histological analysis of Rim3 mutant showed hyperplasia of the epidermal cells in the upper hair follicles and abnormal anagen phase at the first hair cycle. Furthermore, immunohistochemical analysis revealed hyperproliferation and misdifferentiation of the upper follicular epidermis in Rim3 mutant. These results suggest that Gsdma3 is involved in the proliferation and differentiation of epidermal stem cells

Gene expression profiling distinguishes between spontaneous and radiation-induced rat mammary carcinomas

International Nuclear Information System (INIS)

Imaoka, Tatsuhiko; Nishimura, Mayumi; Kakinuma, Shizuko; Shimada, Yoshiya; Yamashita, Satoshi; Ushijima, Toshikazu

2008-01-01

The ability to distinguish between spontaneous and radiation-induced cancers in humans is expected to improve the resolution of estimated risk from low dose radiation. Mammary carcinomas were obtained from Sprague-Dawley rats that were either untreated (n=45) or acutely γ-irradiated (1 Gy; n=20) at seven weeks of age. Gene expression profiles of three spontaneous and four radiation-induced carcinomas, as well as those of normal mammary glands, were analyzed by microarrays. Differential expression of identified genes of interest was then verified by quantitative polymerase chain reaction (qPCR). Cluster analysis of global gene expression suggested that spontaneous carcinomas were distinguished from a heterogeneous population of radiation-induced carcinomas, though most gene expressions were common. We identified 50 genes that had different expression levels between spontaneous and radiogenic carcinomas. We then selected 18 genes for confirmation of the microarray data by qPCR analysis and obtained the following results: high expression of Plg, Pgr and Wnt4 was characteristic to all spontaneous carcinomas; Tnfsf11, Fgf10, Agtr1a, S100A9 and Pou3f3 showed high expression in a subset of radiation-induced carcinomas; and increased Gp2, Areg and Igf2 expression, as well as decreased expression of Ca3 and noncoding RNA Mg1, were common to all carcinomas. Thus, gene expression analysis distinguished between spontaneous and radiogenic carcinomas, suggesting possible differences in their carcinogenic mechanism. (author)

Mutations affecting RNA polymerase I-stimulated exchange and rDNA recombination in yeast

International Nuclear Information System (INIS)

Lin, Y.H.; Keil, R.L.

1991-01-01

HOT1 is a cis-acting recombination-stimulatory sequence isolated from the rDNA repeat unit of yeast. The ability of HOT1 to stimulate mitotic exchange appears to depend on its ability to promote high levels of RNA polymerase I transcription. A qualitative colony color sectoring assay was developed to screen for trans-acting mutations that alter the activity of HOT1. Both hypo-recombination and hyper-recombination mutants were isolated. Genetic analysis of seven HOT1 recombination mutants (hrm) that decrease HOT1 activity shows that they behave as recessive nuclear mutations and belong to five linkage groups. Three of these mutations, hrm1, hrm2, and hrm3, also decrease rDNA exchange but do not alter recombination in the absence of HOT1. Another mutation, hrm4, decreases HOT1-stimulated recombination but does not affect rDNA recombination or exchange in the absence of HOT1. Two new alleles of RAD52 were also isolated using this screen. With regard to HOT1 activity, rad52 is epistatic to all four hrm mutations indicating that the products of the HRM genes and of RAD52 mediate steps in the same recombination pathway. Finding mutations that decrease both the activity of HOT1 and exchange in the rDNA supports the hypothesis that HOT1 plays a role in rDNA recombination

Spontaneous intracranial hypotension.

LENUS (Irish Health Repository)

Fullam, L

2012-01-31

INTRODUCTION: Spontaneous\\/primary intracranial hypotension is characterised by orthostatic headache and is associated with characteristic magnetic resonance imaging findings. CASE REPORT: We present a case report of a patient with typical symptoms and classical radiological images. DISCUSSION: Spontaneous intracranial hypotension is an under-recognised cause of headache and can be diagnosed by history of typical orthostatic headache and findings on MRI brain.

Spontaneous gastric rupture after Sodium Bicarbonate consumption: A case report.

Science.gov (United States)

Vásquez, A; Domínguez, C; Perdomo, C F

2017-08-01

Spontaneous gastric rupture is a rare condition however a prompt diagnosis and treatment are necessary to decrease mortality and morbidity. We report a case of stomach rupture after the ingestion of Sodium Bicarbonate (SB); imaging findings with a brief review of the literature are presented. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Recurrence rate after thoracoscopic surgery for primary spontaneous pneumothorax.

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Dagnegård, Hanna H; Rosén, Alice; Sartipy, Ulrik; Bergman, Per

2017-08-01

There is an on-going discussion regarding the recurrence rate after surgery for primary spontaneous pneumothorax by video assisted thoracic surgery (VATS) or by thoracotomy access. This study aimed to describe the recurrence rate, and to identify a possible learning curve, following surgery for primary spontaneous pneumothorax by VATS. All patients who underwent surgery for primary spontaneous pneumothorax by VATS at Karolinska University Hospital 2004-2013 were reviewed. Preoperative and operative characteristics were obtained from medical records. Patients were followed-up through telephone interviews or questionnaires and by review of medical records. The primary outcome of interest was time to recurrence of pneumothorax requiring intervention. Outcomes were compared between patients operated during 2004-June 2010 and July 2010-2013. 219 patients who underwent 234 consecutive procedures were included. The mean follow-up times were 6.3 and 2.9 years in the early and late period, respectively. The postoperative recurrence rate in the early period was 16% (11%-25%), 18% (12%-27%), and 18% (12%-27%), at 1, 3 and 5 years, compared to 1.7% (0.4%-6.8%), 7.6% (3.7%-15%), and 9.8% (4.8%-19%) at 1, 3 and 5 years, in the late period (p = 0.016). We found that the recurrence rate after thoracoscopic surgery for primary spontaneous pneumothorax decreased significantly during the study period. Our results strongly suggest that thoracoscopic surgery for pneumothorax involve a substantial learning curve.

Insulin decreases atherosclerosis by inducing endothelin receptor B expression

DEFF Research Database (Denmark)

Park, Kyoungmin; Mima, Akira; Li, Qian

2016-01-01

Endothelial cell (EC) insulin resistance and dysfunction, caused by diabetes, accelerates atherosclerosis. It is unknown whether specifically enhancing EC-targeted insulin action can decrease atherosclerosis in diabetes. Accordingly, overexpressing insulin receptor substrate-1 (IRS1...... induction of NO action, which increases endothelin receptor B (EDNRB) expression and intracellular [Ca(2+)]. Using the mice with knockin mutation of eNOS, which had Ser1176 mutated to alanine (AKI), deleting the only known mechanism for insulin to activate eNOS/NO pathway, we observed that IRS1...... overexpression in the endothelia of Aki/ApoE(-/-) mice significantly decreased atherosclerosis. Interestingly, endothelial EDNRB expression was selectively reduced in intima of arteries from diabetic patients and rodents. However, endothelial EDNRB expression was upregulated by insulin via P13K/Akt pathway...

[Spontaneous bacterial peritonitis].

Science.gov (United States)

Velkey, Bálint; Vitális, Eszter; Vitális, Zsuzsanna

2017-01-01

Spontaneous bacterial peritonitis occurs most commonly in cirrhotic patients with ascites. Pathogens get into the circulation by intestinal translocation and colonize in peritoneal fluid. Diagnosis of spontaneous bacterial peritonitis is based on elevated polymorphonuclear leukocyte count in the ascites (>0,25 G/L). Ascites culture is often negative but aids to get information about antibiotic sensitivity in positive cases. Treatment in stable patient can be intravenous then orally administrated ciprofloxacin or amoxicillin/clavulanic acid, while in severe cases intravenous III. generation cephalosporin. Nosocomial spontaneous bacterial peritonitis often caused by Gram-positive bacteria and multi-resistant pathogens can also be expected thus carbapenem should be the choice of the empiric treatment. Antibiotic prophylaxis should be considered. Norfloxacin is used most commonly, but changes are expected due to increase in quinolone resistance. As a primary prophylaxis, a short-term antibiotic treatment is recommended after gastrointestinal bleeding for 5 days, while long-term prophylaxis is for patients with low ascites protein, and advanced disease (400 mg/day). Secondary prophylaxis is recommended for all patients recovered from spontaneous bacterial peritonitis. Due to increasing antibiotic use of antibiotics prophylaxis is debated to some degree. Orv. Hetil., 2017, 158(2), 50-57.

Nonsense mutations in the human β-globin gene affect mRNA metabolism

International Nuclear Information System (INIS)

Baserga, S.J.; Benz, E.J. Jr.

1988-01-01

A number of premature translation termination mutations (nonsense mutations) have been described in the human α- and β-globin genes. Studies on mRNA isolated from patients with β 0 -thalassemia have shown that for both the β-17 and the β-39 mutations less than normal levels of β-globin mRNA accumulate in peripheral blood cells. (The codon at which the mutation occurs designates the name of the mutation; there are 146 codons in human β-globin mRNA). In vitro studies using the cloned β-39 gene have reproduced this effect in a heterologous transfection system and have suggested that the defect resides in intranuclear metabolism. The authors have asked if this phenomenon of decreased mRNA accumulation is a general property of nonsense mutations and if the effect depends on the location or the type of mutation. Toward this end, they have studied the effect of five nonsense mutations and two missense mutations on the expression of human β-globin mRNA in a heterologous transfection system. In all cases studied, the presence of a translation termination codon correlates with a decrease in the steady-state level of mRNA. The data suggest that the metabolism of a mammalian mRNA is affected by the presence of a mutation that affects translation

Extreme muscle development in sheep heterozygous for both myostatin and callipyge mutations

Science.gov (United States)

Two mutations causing increased muscle size and decreased fat content in sheep have been described. The callipyge (CLPG) syndrome is only exhibited after 4 to 6 weeks of age in animals inheriting the mutation solely from their sire. In contrast, a mutation of the myostatin gene (MSTN) in the Texel...

Genetics Home Reference: primary spontaneous pneumothorax

Science.gov (United States)

... Home Health Conditions Primary spontaneous pneumothorax Primary spontaneous pneumothorax Printable PDF Open All Close All Enable Javascript ... view the expand/collapse boxes. Description Primary spontaneous pneumothorax is an abnormal accumulation of air in the ...

Mutation profiling of the hepatitis B virus strains circulating in North Indian population.

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Amit Tuteja

Full Text Available AIMS: The aim of this study was to investigate the genomic mutations in the circulating Hepatitis B virus strains causing infection in the Indian population. Further, we wanted to analyze the biological significance of these mutations in HBV mediated disease. METHODS: 222 HBsAg positive patients were enrolled in the study. The genotype and mutation profile was determined for the infecting HBV isolate by sequencing overlapping fragments. These sequences were analyzed by using different tools and compared with previously available HBV sequence information. Mutation Frequency Index (MFI for the Genes and Diagnosis group was also calculated. RESULTS: HBV Genotype D was found in 55% (n = 121 of the patient group and genotype A was found in 30% (n = 66 of samples. The majority (52% of the HBV-infected individuals in the present study were HBeAg-negative in all the age groups studied. Spontaneous drug associated mutations implicated in resistance to antiviral therapy were also identified in about quarter of our patients, which is of therapeutic concern. The MFI approach used in the study indicated that Core peptide was the most conserved region in both genotypes and Surface peptide had highest mutation frequency. Few mutations in X gene (T36A and G50R showed high frequency of association with HCC. A rare recombinant strain of HBV genotype A and D was also identified in the patient group. CONCLUSIONS: HBV genotype D was found out to be most prevalent. More than half of the patients studied had HBeAg negative disease. Core region was found to be most conserved. Drug Associated mutations were detected in 22% of the patient group and T36A and G50R mutations in X gene were found to be associated with HCC.

Novel Sonic Hedgehog Mutation in a Couple with Variable Expression of Holoprosencephaly

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M. Aguinaga

2011-01-01

Full Text Available Holoprosencephaly (HPE is the most common developmental defect of the forebrain and midface in humans. sporadic and inherited mutations in the human sonic hedgehog (SHH gene cause 37% of familial HPE. A couple was referred to our unit with a family history of two spontaneous first trimester miscarriages and a daughter with HPE who presented early neonatal death. The father had a repaired median cleft lip, absence of central incisors, facial medial hypoplasia, and cleft palate. Intelligence and a brain CT scan were normal. Direct paternal sequencing analysis showed a novel nonsense mutation (W127X. Facial characteristics are considered as HPE microforms, and the pedigree suggested autosomal dominant inheritance with a variable expression of the phenotype. This study reinforces the importance of an exhaustive evaluation of couples with a history of miscarriages and neonatal deaths with structural defects.

Endoscopic hematoma evacuation in patients with spontaneous supratentorial intracerebral hemorrhage

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Wei-Hsin Wang

2015-02-01

Conclusion: With the introduction of the minimally invasive techniques and the evolution of the neuroendoscope and hemostatic agents, the median operative time and blood loss have been significantly decreased. Although the hematoma evacuation rates were similar between the endoscope (90% and craniotomy (85% groups, the median intensive care unit stay was decreased from 11 days to 6 days due to reduced surgical invasiveness. This represents an important advancement in treating spontaneous supratentorial ICH, and provides a measured preview of the promising results that can be expected in the future.

Canine spontaneous head and neck squamous cell carcinomas represent their human counterparts at the molecular level.

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Deli Liu

2015-06-01

Full Text Available Spontaneous canine head and neck squamous cell carcinoma (HNSCC represents an excellent model of human HNSCC but is greatly understudied. To better understand and utilize this valuable resource, we performed a pilot study that represents its first genome-wide characterization by investigating 12 canine HNSCC cases, of which 9 are oral, via high density array comparative genomic hybridization and RNA-seq. The analyses reveal that these canine cancers recapitulate many molecular features of human HNSCC. These include analogous genomic copy number abnormality landscapes and sequence mutation patterns, recurrent alteration of known HNSCC genes and pathways (e.g., cell cycle, PI3K/AKT signaling, and comparably extensive heterogeneity. Amplification or overexpression of protein kinase genes, matrix metalloproteinase genes, and epithelial-mesenchymal transition genes TWIST1 and SNAI1 are also prominent in these canine tumors. This pilot study, along with a rapidly growing body of literature on canine cancer, reemphasizes the potential value of spontaneous canine cancers in HNSCC basic and translational research.

Cell surface fucosylation does not affect development of colon tumors in mice with germline Smad3 mutation

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Domino, Steven E.; Karnak, David M.; Hurd, Elizabeth A.

2006-01-01

Background/Aims: Neoplasia-related alterations in cell surface α(1,2)fucosylated glycans have been reported in multiple tumors including colon, pancreas, endometrium, cervix, bladder, lung, and choriocarcinoma. Spontaneous colorectal tumors from mice with a germline null mutation of transforming growth factor-β signaling gene Smad3 (Madh3) were tested for α(1,2)fucosylated glycan expression. Methods: Ulex Europaeus Agglutinin-I lectin staining, fucosyltransferase gene northern blot analysis, and a cross of mutant mice with Fut2 and Smad3 germline mutations were performed. Results: Spontaneous colorectal tumors from Smad3 (-/-) homozygous null mice were found to express α(1,2)fucosylated glycans in an abnormal pattern compared to adjacent nonneoplastic colon. Northern blot analysis of α(1,2)fucosyltransferase genes Fut1 and Fut2 revealed that Fut2, but not Fut1, steady-state mRNA levels were significantly increased in tumors relative to adjacent normal colonic mucosa. Mutant mice with a Fut2-inactivating germline mutation were crossed with Smad3 targeted mice. In Smad3 (-/-)/Fut2 (-/-) double knock-out mice, UEA-I lectin staining was eliminated from colon and colon tumors, however, the number and size of tumors present by 24 weeks of age did not vary regardless of the Fut2 genotype. Conclusions: In this model of colorectal cancer, cell surface α(1,2)fucosylation does not affect development of colon tumors. PMID:17264540

Lineage dynamics and mutation-selection balance in non-adapting asexual populations

Science.gov (United States)

Pénisson, Sophie; Sniegowski, Paul D.; Colato, Alexandre; Gerrish, Philip J.

2013-02-01

In classical population genetics, mutation-selection balance refers to the equilibrium frequency of a deleterious allele established and maintained under two opposing forces: recurrent mutation, which tends to increase the frequency of the allele; and selection, which tends to decrease its frequency. In a haploid population, if μ denotes the per capita rate of production of the deleterious allele by mutation and s denotes the selective disadvantage of carrying the allele, then the classical mutation-selection balance frequency of the allele is approximated by μ/s. This calculation assumes that lineages carrying the mutant allele in question—the ‘focal allele’—do not accumulate deleterious mutations linked to the focal allele. In principle, indirect selection against the focal allele caused by such additional mutations can decrease the frequency of the focal allele below the classical mutation-selection balance. This effect of indirect selection will be strongest in an asexual population, in which the entire genome is in linkage. Here, we use an approach based on a multitype branching process to investigate this effect, analyzing lineage dynamics under mutation, direct selection, and indirect selection in a non-adapting asexual population. We find that the equilibrium balance between recurrent mutation to the focal allele and the forces of direct and indirect selection against the focal allele is closely approximated by γμ/(s + U) (s = 0 if the focal allele is neutral), where γ ≈ eθθ-(ω+θ)(ω + θ)(Γ(ω + θ) - Γ(ω + θ,θ)), \\theta =U/\\tilde {s}, and \\omega =s/\\tilde {s}; U denotes the genomic deleterious mutation rate and \\tilde {s} denotes the geometric mean selective disadvantage of deleterious mutations elsewhere on the genome. This mutation-selection balance for asexual populations can remain surprisingly invariant over wide ranges of the mutation rate.

Spontaneous Tumor Lysis Syndrome

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Alicia C. Weeks MD

2015-08-01

Full Text Available Tumor lysis syndrome (TLS is a known complication of malignancy and its treatment. The incidence varies on malignancy type, but is most common with hematologic neoplasms during cytotoxic treatment. Spontaneous TLS is thought to be rare. This case study is of a 62-year-old female admitted with multisystem organ failure, with subsequent diagnosis of aggressive B cell lymphoma. On admission, laboratory abnormalities included renal failure, elevated uric acid (20.7 mg/dL, and 3+ amorphous urates on urinalysis. Oliguric renal failure persisted despite aggressive hydration and diuretic use, requiring initiation of hemodialysis prior to chemotherapy. Antihyperuricemic therapy and hemodialysis were used to resolve hyperuricemia. However, due to multisystem organ dysfunction syndrome with extremely poor prognosis, the patient ultimately expired in the setting of a terminal ventilator wean. Although our patient did not meet current TLS criteria, she required hemodialysis due to uric acid nephropathy, a complication of TLS. This poses the clinical question of whether adequate diagnostic criteria exist for spontaneous TLS and if the lack of currently accepted guidelines has resulted in the underestimation of its incidence. Allopurinol and rasburicase are commonly used for prevention and treatment of TLS. Although both drugs decrease uric acid levels, allopurinol mechanistically prevents formation of the substrate rasburicase acts to solubilize. These drugs were administered together in our patient, although no established guidelines recommend combined use. This raises the clinical question of whether combined therapy is truly beneficial or, conversely, detrimental to patient outcomes.

Fixation probability of a nonmutator in a large population of asexual mutators.

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Jain, Kavita; James, Ananthu

2017-11-21

In an adapted population of mutators in which most mutations are deleterious, a nonmutator that lowers the mutation rate is under indirect selection and can sweep to fixation. Using a multitype branching process, we calculate the fixation probability of a rare nonmutator in a large population of asexual mutators. We show that when beneficial mutations are absent, the fixation probability is a nonmonotonic function of the mutation rate of the mutator: it first increases sublinearly and then decreases exponentially. We also find that beneficial mutations can enhance the fixation probability of a nonmutator. Our analysis is relevant to an understanding of recent experiments in which a reduction in the mutation rates has been observed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Graphite fiber/copper composites prepared by spontaneous infiltration

Science.gov (United States)

Wang, Hongbao; Tao, Zechao; Li, Xiangfen; Yan, Xi; Liu, Zhanjun; Guo, Quangui

2018-05-01

The major bottleneck in developing graphite fiber reinforced copper (GF/Cu) composites is the poor wettability of Cu/graphite system. Alloying element of chromium (Cr) is introduced to improve the wettability of liquid copper on graphite. Sessile drop method experiments illustrate that the contact angle of liquid Cu-Cr (1.0 wt.%) alloy on graphite substrate decreases to 43° at 1300 °C. The improvement of wettability is related to the formation of chromium carbide layer at interface zone. Based on the wetting experiment, a spontaneous infiltration method for preparing GF/Cu composites is proposed. Unidirectional GF preforms are infiltrated by Cu-Cr alloys without external pressure in a tubular furnace. Results reveal that the GF preform can be fully infiltrated by Cu-Cr alloy (8 wt.%) spontaneously when fiber volume fraction is 40%. The coefficient of thermal expansion (CTE) of GF/Cu-Cr (8.0 wt.%) composites is 4.68 × 10-6/K along the longitudinal direction.

FKS2 Mutations Associated with Decreased Echinocandin Susceptibility of Candida glabrata following Anidulafungin Therapy

OpenAIRE

Costa-de-Oliveira, Sofia; Miranda, Isabel Marcos; Silva, Raquel M.; Pinto e Silva, Ana; Rocha, Rita; Amorim, Antonio; Rodrigues, Acacio Goncalves; Pina-Vaz, Cidalia

2011-01-01

This is the first case report of Candida glabrata-disseminated candidiasis describing the acquisition of echinocandin resistance following anidulafungin treatment. The initial isolates recovered were susceptible to echinocandins. However, during 27 days of anidulafungin treatment, two resistant strains were isolated (from the blood and peritoneal fluid). The resistant peritoneal fluid isolate exhibited a Ser663Pro mutation in position 1987 of FKS2 HS1 (hot spot 1), whereas the resistant blood...

Early maturing mutations as germplasm stocks for barley breeding

International Nuclear Information System (INIS)

Ukai, Yasuo

1985-01-01

A total of 102 early maturing mutations have been isolated after various treatments of seeds or plants with ionizing radiations or chemicals from a barley cultivar 'Chikurin Ibaraki 1' or its mutants. Fifty of them were evaluated as regards responses to internal physiological factors. The mutants were found to have a mutational alteration in vernalization and/or photoperiodic response. Earliness in a narrow sense was not noticeably changed. The original genotype is a winter and long-day type. By mutation four different degrees of change in vernalization requirement i.e. complete (V 1 ) and incomplete (V 2 ) spring habit and winter habit with reduced requirement to varying degrees (V 3 , V 4 ) have been produced. Photoperiodic response was also changed into at least three types i.e. complete (P 1 ) and incomplete (P 2 ) loss of sensitivity to short photoperiod and a slight reduction in critical daylength for heading. P 1 and P 2 type mutants were all characterized by marked earliness in heading time in field. Thirty seven mutants were located in seven separate loci. Allelism test of the mutated genes to spontaneous ones revealed that the genes carried by P 1 type mutants were all allelic to an earliness gene ea sub(k) on chromosome 5 and the gene involved in P 2 type mutants to ea 7 on chromosome 6. On the contrary, the gene commonly involved in all V 1 type mutants and one V 2 type mutant was not allelic to spring habit gene Sh 2 or Sh 3 . It seemed likely that the gene was not allelic to, either, but closely linked with sh on chromosome 4. The diversity in terms of genetic and physiological properties of the early maturing mutants arising from common ancestry emphasizes the importance of induced mutation in broadening of germplasm of barley breeding. (author)

Environmental modulation of somatic mutations: nature of interactions. Final report, 1 June 1974--31 May 1977

International Nuclear Information System (INIS)

Mericle, L.W.

1977-05-01

Research on this project has had as a major goal a combined ecologic-genetic investigation of somatic mutations in order to evaluate the impacts of certain changing environmental parameters. The ultimate aim, to better understand how such environmental-mutation interactions operate and to assure the information obtained be extrapolatable to conditions and events in nature. Higher plants delineate reproductive tissues late in development from meristematic, somatic tissues. Moreover, the prevailing method of reproduction may be without sexual fusion of gametes and/or wholly asexual (vegetative). Therefore, somatic mutations can have as far-reaching genetic significance for a plant population as when germ cells, themselves, are directly affected. Our data show diurnal temperature differences (DTD) of greater than or equal to 22.2 C-degrees to be very effective mutagenic agents in the Tradescantia somatic mutation system. Further, these ranges of DTD were found to occur often in important seed production areas. A DTD of 22.2 in magnitude can increase mutations 10-fold. And, durations short as 1-day can induce significant increases in mutation rate. Whether interaction of 22.2 DTD with low-level radiation (800 mR/day) is synergistic or attenuative is still debatable. We believe, however, that spontaneous, and 22.2 DTD induced, mutations occur mainly via the genetic mechanism of somatic crossing-over; mutations from acute ionizing radiation (e.g., 30-60 R γ) via chromosome breakage, producing micronuclei. Requirements for maximizing the Discriminatory Response Capability (DRC) in the Tradescantia somatic mutation system are set forth

Research on spontaneous activity in adult anisometropic amblyopia with regional homogeneity

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Huang, Yufeng; Zhou, Yifeng

2017-06-01

Amblyopia usually occurs in early childhood and results in monocular visual impairment. The functional magnetic resonance imaging (fMRI) studies have reflected functional anomaly in amblyopia. In resting-state fMRI study, spontaneous activity changes abnormally in anisometropic amblyopia could be revealed by the regional homogeneity (ReHo). Twenty two adult anisometropic amblyopes and Twenty one normal controls participated in this fMRI study. Two sample T test was carried out to analysis ReHo within the whole brain for the inter groups. Compare with normal group, our study found that the amblyopia’s ReHo mainly increased in the left frontal lobe, while decreased in the left cerebellum, the temporal lobe (left and right), and the left parietal lobe. And the ReHo values in middle and inferior temporal lobe, the prefrontal lobe, frontal lobe (positive) and parietal lobe and medial frontal gyrus (negative) could be correlated with the acuity deficit of amblyopia. The results increased in ReHo may indicate compensatory plasticity in higher vision information process, while the decreased in ReHo may reflect decreased ability in eye movement, spatial sense and visuo-motor coordination. The correlation revealed that the vision deficit may correspond to the spontaneous in certain brain area.

The ter mutation in the rat Dnd1 gene initiates gonadal teratomas and infertility in both genders.

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Northrup, Emily; Zschemisch, Nils-Holger; Eisenblätter, Regina; Glage, Silke; Wedekind, Dirk; Cuppen, Edwin; Dorsch, Martina; Hedrich, Hans-Jürgen

2012-01-01

A spontaneous mutation leading to the formation of congenital ovarian and testicular tumors was detected in the WKY/Ztm rat strain. The histological evaluation revealed derivatives from all three germ layers, thereby identifying these tumors as teratomas. Teratocarcinogenesis was accompanied by infertility and the underlying mutation was termed ter. Linkage analysis of 58 (WKY-ter×SPRD-Cu3) F2 rats associated the ter mutation with RNO18 (LOD = 3.25). Sequencing of candidate genes detected a point mutation in exon 4 of the dead-end homolog 1 gene (Dnd1), which introduces a premature stop codon assumed to cause a truncation of the Dnd1 protein. Genotyping of the recessive ter mutation revealed a complete penetrance of teratocarcinogenesis and infertility in homozygous ter rats of both genders. Morphologically non-tumorous testes of homozygous ter males were reduced in both size and weight. This testicular malformation was linked to a lack of spermatogenesis using immunohistochemical and histological staining. Our WKY-Dnd1(ter)/Ztm rat is a novel animal model to investigate gonadal teratocarcinogenesis and the molecular mechanisms involved in germ cell development of both genders.

Spontaneously immortalised bovine mammary epithelial cells exhibit a distinct gene expression pattern from the breast cancer cells

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Li Qianqian

2010-10-01

Full Text Available Abstract Background Spontaneous immortalisation of cultured mammary epithelial cells (MECs is an extremely rare event, and the molecular mechanism behind spontaneous immortalisation of MECs is unclear. Here, we report the establishment of a spontaneously immortalised bovine mammary epithelial cell line (BME65Cs and the changes in gene expression associated with BME65Cs cells. Results BME65Cs cells maintain the general characteristics of normal mammary epithelial cells in morphology, karyotype and immunohistochemistry, and are accompanied by the activation of endogenous bTERT (bovine Telomerase Reverse Transcriptase and stabilisation of the telomere. Currently, BME65Cs cells have been passed for more than 220 generations, and these cells exhibit non-malignant transformation. The expression of multiple genes was investigated in BME65Cs cells, senescent BMECs (bovine MECs cells, early passage BMECs cells and MCF-7 cells (a human breast cancer cell line. In comparison with early passage BMECs cells, the expression of senescence-relevant apoptosis-related gene were significantly changed in BME65Cs cells. P16INK4a was downregulated, p53 was low expressed and Bax/Bcl-2 ratio was reversed. Moreover, a slight upregulation of the oncogene c-Myc, along with an undetectable level of breast tumor-related gene Bag-1 and TRPS-1, was observed in BME65Cs cells while these genes are all highly expressed in MCF-7. In addition, DNMT1 is upregulated in BME65Cs. These results suggest that the inhibition of both senescence and mitochondrial apoptosis signalling pathways contribute to the immortality of BME65Cs cells. The expression of p53 and p16INK4a in BME65Cs was altered in the pattern of down-regulation but not "loss", suggesting that this spontaneous immortalization is possibly initiated by other mechanism rather than gene mutation of p53 or p16INK4a. Conclusions Spontaneously immortalised BME65Cs cells maintain many characteristics of normal BMEC cells and

Spontaneous cervical epidural hematoma: Report of a case managed conservatively

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Halim Tariq

2008-01-01

Full Text Available Spontaneous spinal epidural hematoma is a rare cause of acute spinal cord compression. A 25-year-old male presented with a history of sudden onset of complete quadriplegia with sensory loss below the neck along with loss of bowel and bladder control. He had no history of any constitutional symptoms. He reported 10 days later. He was managed conservatively and after two weeks of intensive rehabilitation he had complete neural recovery. The spontaneous recovery of neurological impairment is attributed to the spreading of the hematoma throughout the epidural space, thus decreasing the pressure with partial neural recovery. Conservative treatment is a fair option in young patients who present late and show neurological improvement. The neurological status on presentation will guide the further approach to management.

Cox1 mutation abrogates need for Cox23 in cytochrome c oxidase biogenesis

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Richard Dela Cruz

2016-06-01

Full Text Available Cox23 is a known conserved assembly factor for cytochrome c oxidase, although its role in cytochrome c oxidase (CcO biogenesis remains unresolved. To gain additional insights into its role, we isolated spontaneous suppressors of the respiratory growth defect in cox23∆ yeast cells. We recovered independent colonies that propagated on glycerol/lactate medium for cox23∆ cells at 37°C. We mapped these mutations to the mitochondrial genome and specifically to COX1 yielding an I101F substitution. The I101F Cox1 allele is a gain-of-function mutation enabling yeast to respire in the absence of Cox23. CcO subunit steady-state levels were restored with the I101F Cox1 suppressor mutation and oxygen consumption and CcO activity were likewise restored. Cells harboring the mitochondrial genome encoding I101F Cox1 were used to delete genes for other CcO assembly factors to test the specificity of the Cox1 mutation as a suppressor of cox23∆ cells. The Cox1 mutant allele fails to support respiratory growth in yeast lacking Cox17, Cox19, Coa1, Coa2, Cox14 or Shy1, demonstrating its specific suppressor activity for cox23∆ cells.

Decreased spontaneous eye blink rates in chronic cannabis users: evidence for striatal cannabinoid-dopamine interactions.

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Mikael A Kowal

Full Text Available Chronic cannabis use has been shown to block long-term depression of GABA-glutamate synapses in the striatum, which is likely to reduce the extent to which endogenous cannabinoids modulate GABA- and glutamate-related neuronal activity. The current study aimed at investigating the effect of this process on striatal dopamine levels by studying the spontaneous eye blink rate (EBR, a clinical marker of dopamine level in the striatum. 25 adult regular cannabis users and 25 non-user controls matched for age, gender, race, and IQ were compared. Results show a significant reduction in EBR in chronic users as compared to non-users, suggesting an indirect detrimental effect of chronic cannabis use on striatal dopaminergic functioning. Additionally, EBR correlated negatively with years of cannabis exposure, monthly peak cannabis consumption, and lifetime cannabis consumption, pointing to a relationship between the degree of impairment of striatal dopaminergic transmission and cannabis consumption history.

Validation of high-resolution DNA melting analysis for mutation scanning of the CDKL5 gene: identification of novel mutations.

Science.gov (United States)

Raymond, Laure; Diebold, Bertrand; Leroux, Céline; Maurey, Hélène; Drouin-Garraud, Valérie; Delahaye, Andre; Dulac, Olivier; Metreau, Julia; Melikishvili, Gia; Toutain, Annick; Rivier, François; Bahi-Buisson, Nadia; Bienvenu, Thierry

2013-01-01

Mutations in the cyclin-dependent kinase-like 5 gene (CDKL5) have been predominantly described in epileptic encephalopathies of female, including infantile spasms with Rett-like features. Up to now, detection of mutations in this gene was made by laborious, expensive and/or time consuming methods. Here, we decided to validate high-resolution melting analysis (HRMA) for mutation scanning of the CDKL5 gene. Firstly, using a large DNA bank consisting to 34 samples carrying different mutations and polymorphisms, we validated our analytical conditions to analyse the different exons and flanking intronic sequences of the CDKL5 gene by HRMA. Secondly, we screened CDKL5 by both HRMA and denaturing high performance liquid chromatography (dHPLC) in a cohort of 135 patients with early-onset seizures. Our results showed that point mutations and small insertions and deletions can be reliably detected by HRMA. Compared to dHPLC, HRMA profiles are more discriminated, thereby decreasing unnecessary sequencing. In this study, we identified eleven novel sequence variations including four pathogenic mutations (2.96% prevalence). HRMA appears cost-effective, easy to set up, highly sensitive, non-toxic and rapid for mutation screening, ideally suited for large genes with heterogeneous mutations located along the whole coding sequence, such as the CDKL5 gene. Copyright © 2012 Elsevier B.V. All rights reserved.

Humidification performance of humidifying devices for tracheostomized patients with spontaneous breathing: a bench study.

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Chikata, Yusuke; Oto, Jun; Onodera, Mutsuo; Nishimura, Masaji

2013-09-01

Heat and moisture exchangers (HMEs) are commonly used for humidifying respiratory gases administered to mechanically ventilated patients. While they are also applied to tracheostomized patients with spontaneous breathing, their performance in this role has not yet been clarified. We carried out a bench study to investigate the effects of spontaneous breathing parameters and oxygen flow on the humidification performance of 11 HMEs. We evaluated the humidification provided by 11 HMEs for tracheostomized patients, and also by a system delivering high-flow CPAP, and an oxygen mask with nebulizer heater. Spontaneous breathing was simulated with a mechanical ventilator, lung model, and servo-controlled heated humidifier at tidal volumes of 300, 500, and 700 mL, and breathing frequencies of 10 and 20 breaths/min. Expired gas was warmed to 37°C. The high-flow CPAP system was set to deliver 15, 30, and 45 L/min. With the 8 HMEs that were equipped with ports to deliver oxygen, and with the high-flow CPAP system, measurements were taken when delivering 0 and 3 L/min of dry oxygen. After stabilization we measured the absolute humidity (AH) of inspired gas with a hygrometer. AH differed among HMEs applied to tracheostomized patients with spontaneous breathing. For all the HMEs, as tidal volume increased, AH decreased. At 20 breaths/min, AH was higher than at 10 breaths/min. For all the HMEs, when oxygen was delivered, AH decreased to below 30 mg/L. With an oxygen mask and high-flow CPAP, at all settings, AH exceeded 30 mg/L. None of the HMEs provided adequate humidification when supplemental oxygen was added. In the ICU, caution is required when applying HME to tracheostomized patients with spontaneous breathing, especially when supplemental oxygen is required.

Prevalence, Mutation Patterns, and Effects on Protease Inhibitor Susceptibility of the L76V Mutation in HIV-1 Protease▿ †

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Young, Thomas P.; Parkin, Neil T.; Stawiski, Eric; Pilot-Matias, Tami; Trinh, Roger; Kempf, Dale J.; Norton, Michael

2010-01-01

Patterns of HIV-1 protease inhibitor (PI) resistance-associated mutations (RAMs) and effects on PI susceptibility associated with the L76V mutation were studied in a large database. Of 20,501 sequences with ≥1 PI RAM, 3.2% contained L76V; L76V was alone in 0.04%. Common partner mutations included M46I, I54V, V82A, I84V, and L90M. L76V was associated with a 2- to 6-fold decrease in susceptibility to lopinavir, darunavir, amprenavir, and indinavir and a 7- to 8-fold increase in susceptibility to atazanavir and saquinavir. PMID:20805393

Effect of SOS-induced levels of imuABC on spontaneous and damage-induced mutagenesis in Caulobacter crescentus.

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Alves, Ingrid R; Lima-Noronha, Marco A; Silva, Larissa G; Fernández-Silva, Frank S; Freitas, Aline Luiza D; Marques, Marilis V; Galhardo, Rodrigo S

2017-11-01

imuABC (imuAB dnaE2) genes are responsible for SOS-mutagenesis in Caulobacter crescentus and other bacterial species devoid of umuDC. In this work, we have constructed operator-constitutive mutants of the imuABC operon. We used this genetic tool to investigate the effect of SOS-induced levels of these genes upon both spontaneous and damage-induced mutagenesis. We showed that constitutive expression of imuABC does not increase spontaneous or damage-induced mutagenesis, nor increases cellular resistance to DNA-damaging agents. Nevertheless, the presence of the operator-constitutive mutation rescues mutagenesis in a recA background, indicating that imuABC are the only genes required at SOS-induced levels for translesion synthesis (TLS) in C. crescentus. Furthermore, these data also show that TLS mediated by ImuABC does not require RecA, unlike umuDC-dependent mutagenesis in E. coli. Copyright © 2017 Elsevier B.V. All rights reserved.

Spontaneous rib fractures.

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Katrancioglu, Ozgur; Akkas, Yucel; Arslan, Sulhattin; Sahin, Ekber

2015-07-01

Other than trauma, rib fracture can occur spontaneously due to a severe cough or sneeze. In this study, patients with spontaneous rib fractures were analyzed according to age, sex, underlying pathology, treatment, and complications. Twelve patients who presented between February 2009 and February 2011 with spontaneous rib fracture were reviewed retrospectively. The patients' data were evaluated according to anamnesis, physical examination, and chest radiographs. The ages of the patients ranged from 34 to 77 years (mean 55.91 ± 12.20 years), and 7 (58.4%) were male. All patients had severe cough and chest pain. The fractures were most frequently between 4th and 9th ribs; multiple rib fractures were detected in 5 (41.7%) patients. Eight (66.7%) patients had chronic obstructive pulmonary disease, 2 (16.7%) had bronchial asthma, and 2 (16.7%) had osteoporosis. Bone densitometry revealed a high risk of bone fracture in all patients. Patients with chronic obstructive pulmonary disease or bronchial asthma had been treated with high-dose steroids for over a year. Spontaneous rib fracture due to severe cough may occur in patients with osteoporosis, chronic obstructive pulmonary disease, or bronchial asthma, receiving long-term steroid therapy. If these patients have severe chest pain, chest radiography should be performed to check for bone lesions. © The Author(s) 2015.

Fast maximum likelihood estimation of mutation rates using a birth-death process.

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Wu, Xiaowei; Zhu, Hongxiao

2015-02-07

Since fluctuation analysis was first introduced by Luria and Delbrück in 1943, it has been widely used to make inference about spontaneous mutation rates in cultured cells. Under certain model assumptions, the probability distribution of the number of mutants that appear in a fluctuation experiment can be derived explicitly, which provides the basis of mutation rate estimation. It has been shown that, among various existing estimators, the maximum likelihood estimator usually demonstrates some desirable properties such as consistency and lower mean squared error. However, its application in real experimental data is often hindered by slow computation of likelihood due to the recursive form of the mutant-count distribution. We propose a fast maximum likelihood estimator of mutation rates, MLE-BD, based on a birth-death process model with non-differential growth assumption. Simulation studies demonstrate that, compared with the conventional maximum likelihood estimator derived from the Luria-Delbrück distribution, MLE-BD achieves substantial improvement on computational speed and is applicable to arbitrarily large number of mutants. In addition, it still retains good accuracy on point estimation. Published by Elsevier Ltd.

High Resolution Melting Analysis for Detecting p53 Gene Mutations in Patients with Non-small Cell Lung Cancer

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Zhihong CHEN

2011-10-01

Full Text Available Background and objective It has been proven that p53 gene was related to many human cancers. The mutations in p53 gene play an important role in carcinogensis and mostly happened in exon 5-8. The aim of this study is to establish a high resolution melting (HRM assay to detect p53 mutations from patients with non-small cell lung cancer (NSCLC, to investigate the characteristics of p53 gene mutations, and to analyze the relationship between p53 mutations and evolution regularity of pathogenesis. Methods p53 mutations in exon 5-8 were detected by HRM assay on DNA insolated from 264 NSCLC samples derived from tumor tissues and 54 control samples from pericancerous pulmonary tissues. The mutation samples by the HRM assay were confirmed by sequencing technique. Samples which were positive by HRM but wild type by sequencing were further confirmed by sub-clone and sequencing. Results No mutation was found in 54 pericancerous pulmonary samples by HRM assay. 104 of the 264 tumor tissues demonstrated mutation curves by HRM assay, 102 samples were confirmed by sequencing, including 95 point mutations and 7 frame shift mutations by insertion or deletion. The mutation rate of p53 gene was 39.4%. The mutation rate from exon 5-8 were 11.7%, 8%, 12.5% and 10.6%, respectively and there was no statistically significant difference between them (P=0.35. p53 mutations were significantly more frequent in males than that in females, but not related to the other clinicopathologic characteristics. Conclusion The results indicate that HRM is a sensitive in-tube methodology to detect for mutations in clinical samples. The results suggest that the arising p53 mutations in NSCLC may be due to spontaneous error in DNA synthesis and repair.

Thermal Expansion Anomaly and Spontaneous Magnetostriction of Y2Fe14Al3 Compound

International Nuclear Information System (INIS)

Yan-Ming, Hao; Xin-Yuan, Jiang; Chun-Jing, Gao; Yan-Zhao, Wu; Yan-Yan, Zhang

2009-01-01

The structure and magnetic properties of Y 2 Fe 14 Al 3 compound are investigated by means of x-ray diffraction and magnetization measurements. The Y 2 Fe 14 Al 3 compound has a hexagonal Th 2 Ni 17 -type structure. Negative thermal expansion is found in Y 2 Fe 14 Al 3 compound in the temperature range from 403 to 491K by x-ray dilatometry. The coefficient of the average thermal expansion is α-bar = –2.54 × 10 −5 K −1 . The spontaneous magnetostrictive deformations from 283 to 470K are calculated by means of the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation ω S decreases from 5.74 × 10 −3 to nearly zero with temperature increasing from 283 to 470 K, the spontaneous linear magnetostrictive deformation λ c along the c-axis is larger than the spontaneous linear magnetostrictive deformation λ a in basal-plane in the same temperature below 350 K

Changes in frequency of spontaneous oscillations in procerebrum correlate to behavioural choice in terrestrial snails

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Elena Samarova

2009-08-01

Full Text Available The aim of our study was to understand functional significance of spontaneous oscillations of local field potential in the olfactory brain lobe of terrestrial snail, the procerebrum (PC. We compared changes in frequency of oscillations in semi-intact preparations from snails trained to percept the same conditioned odor as positive (associated with food reinforcement or negative (associated with noxious reinforcement. In vivo recordings in freely behaving naïve snails showed a significant decrease of spontaneous PC oscillations frequency during a stage of tentacle withdrawal to odor presentation. In in vitro preparations from naïve snails, a similar decrease in frequency of the PC oscillations to odor presentation was observed. Changes in frequency of the oscillations to cineole presentations in the “aversive” group of snails (demonstrating withdrawal were much more pronounced than in naïve snails. No significant difference in responses to 5 and 20% cineole was noted. Changes in the spontaneous oscillations frequency in the snails trained to respond with positive reaction (approach to cineole depended on the concentration of the applied odor, and these responses were qualitatively similar to responses of other groups during the first 10 s of responses to odor, but significantly different (increase in PC oscillations frequency from the responses of the aversively trained and naïve snails in the interval 11-30 s, which corresponds to the end of the tentacle withdrawal and timing of decision making (approach or escape in the free behaving snails. Obtained results suggest that frequency of the PC lobe spontaneous oscillations correlate to the choice of behavior in snails: withdrawal (decrease in frequency or approach (increase in frequency to the source of odor.

Immunoexpression of CD30 and CD30 ligand in deciduas from spontaneous abortions

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M Trovato

2009-06-01

Full Text Available In the present study, using immunohistochemistry, we studied the expression of CD30 and CD30-L in 35 deciduas obtained from women following elective abortion during normal physiological gestation and in 60 deciduas obtained from women after spontaneous abortion with or without signs of inflammation. The main difference was noticed in the first trimester of gestation in which was found a decrease in CD30/CD30-L-positive decidual glandular and stromal cells in a greater number of cases of spontaneous abortions with respect to cases of physiological pregnancies (70% vs 50%, p<0.05. In addition, deciduas from spontaneous abortions with inflammation and without inflammation reacted similarly. The reduced expression of CD30 and CD30-L and their cellular pattern detected in the deciduas from spontaneous abortions suggest that the CD30/CD30-L system is crucial for preventing abortions in the first trimester. And furthermore, the distinctive expression of CD30/CD30- L in deciduas from physiological pregnancies may indicate that the CD30/CD30-L system exerts its main role in the first trimester.

Changes in plasma membrane state of thymocytes during spontaneous and radiation-induced leukemogenesis

International Nuclear Information System (INIS)

Gonta-Grabiec, K.

1984-01-01

Changes in plasma membrane properties characteristic for malignant cells were reviewed. Investigations of spontaneous (in AKR mice) and radiation-induced (in C57Bl) leukemogenesis were carried out; changes in properties of Na + , K + ATPase and alkaline phosphatase were characterized. On the basis of the results reported a pre-leukemic stage was distinguished, corresponding to the following features at the cellular level: increase in activity of alkaline phosphatase; decrease in relative activity of Na + , K + ATPase; decrease in efficiency of the Na + K + pump; decrease in cAMP content. 473 refs. (author)

Spontaneous appearance of Tay-Sachs disease in an animal model.

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Zeng, B J; Torres, P A; Viner, T C; Wang, Z H; Raghavan, S S; Alroy, J; Pastores, G M; Kolodny, E H

2008-01-01

Tay-Sachs disease (TSD) is a progressive neurodegenerative disorder due to an autosomal recessively inherited deficiency of beta-hexosaminidase A (Hex A). Deficiency of Hex A in TSD is caused by a defect of the alpha-subunit resulting from mutations of the HEXA gene. To date, there is no effective treatment for TSD. Animal models of genetic diseases, similar to those known to exist in humans, are valuable and essential research tools for the study of potentially effective therapies. However, there is no ideal animal model of TSD available for use in therapeutic trials. In the present study, we report an animal model (American flamingo; Phoenicopterus ruber) of TSD with Hex A deficiency occurring spontaneously in nature, with accumulation of G(M2)-ganglioside, deficiency of Hex A enzymatic activity, and a homozygous P469L mutation in exon 12 of the hexa gene. In addition, we have isolated the full-length cDNA sequence of the flamingo, which consists of 1581 nucleotides encoding a protein of 527 amino acids. Its coding sequence indicates approximately 71% identity at the nucleotide level and about 72.5% identity at the amino acid level with the encoding region of the human HEXA gene. This animal model, with many of the same features as TSD in humans, could represent a valuable resource for investigating therapy of TSD.

Spontaneous tension haemopneumothorax.

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Patterson, Benjamin Oliver; Itam, Sarah; Probst, Fey

2008-10-31

We present a patient with sudden onset progressive shortness of breath and no history of trauma, who rapidly became haemodynamically compromised with a pneumothorax and pleural effusion seen on chest radiograph. He was treated for spontaneous tension pneumothorax but this was soon revealed to be a tension haemopneumothorax. He underwent urgent thoracotomy after persistent bleeding to explore an apical vascular abnormality seen on CT scanning. To our knowledge this is the first such case reported.Aetiology and current approach to spontaneous haemothorax are discussed briefly.

A rat model of hypohidrotic ectodermal dysplasia carries a missense mutation in the Edaradd gene

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2011-01-01

Background Hypohidrotic ectodermal dysplasia (HED) is a congenital disorder characterized by sparse hair, oligodontia, and inability to sweat. It is caused by mutations in any of three Eda pathway genes: ectodysplasin (Eda), Eda receptor (Edar), and Edar-associated death domain (Edaradd), which encode ligand, receptor, and intracellular adaptor molecule, respectively. The Eda signaling pathway activates NF-κB, which is central to ectodermal differentiation. Although the causative genes and the molecular pathway affecting HED have been identified, no curative treatment for HED has been established. Previously, we found a rat spontaneous mutation that caused defects in hair follicles and named it sparse-and-wavy (swh). Here, we have established the swh rat as the first rat model of HED and successfully identified the swh mutation. Results The swh/swh rat showed sparse hair, abnormal morphology of teeth, and absence of sweat glands. The ectoderm-derived glands, meibomian, preputial, and tongue glands, were absent. We mapped the swh mutation to the most telomeric part of rat Chr 7 and found a Pro153Ser missense mutation in the Edaradd gene. This mutation was located in the death domain of EDARADD, which is crucial for signal transduction and resulted in failure to activate NF-κB. Conclusions These findings suggest that swh is a loss-of-function mutation in the rat Edaradd and indicate that the swh/swh rat would be an excellent animal model of HED that could be used to investigate the pathological basis of the disease and the development of new therapies. PMID:22013926

Isolation and characterization of mutated alcohol oxidases from the yeast Hansenula polymorpha with decreased affinity toward substrates and their use as selective elements of an amperometric biosensor

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Schuhmann Wolfgang

2007-06-01

Full Text Available Abstract Background Accurate, rapid, and economic on-line analysis of ethanol is very desirable. However, available biosensors achieve saturation at very low ethanol concentrations and thus demand the time and labour consuming procedure of sample dilution. Results Hansenula polymorpha (Pichia angusta mutant strains resistant to allyl alcohol in methanol medium were selected. Such strains possessed decreased affinity of alcohol oxidase (AOX towards methanol: the KM values for AOX of wild type and mutant strains CA2 and CA4 are shown to be 0.62, 2.48 and 1.10 mM, respectively, whereas Vmax values are increased or remain unaffected. The mutant AOX alleles from H. polymorpha mutants CA2 and CA4 were isolated and sequenced. Several point mutations in the AOX gene, mostly different between the two mutant alleles, have been identified. Mutant AOX forms were isolated and purified, and some of their biochemical properties were studied. An amperometric biosensor based on the mutated form of AOX from the strain CA2 was constructed and revealed an extended linear response to the target analytes, ethanol and formaldehyde, as compared to the sensor based on the native AOX. Conclusion The described selection methodology opens up the possibility of isolating modified forms of AOX with further decreased affinity toward substrates without reduction of the maximal velocity of reaction. It can help in creation of improved ethanol biosensors with a prolonged linear response towards ethanol in real samples of wines, beers or fermentation liquids.

Spontaneous large-scale autolysis in Clostridium acetobutylicum contributes to generation of more spores

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Zhen eLiu

2015-09-01

Full Text Available Autolysis is a widespread phenomenon in bacteria. In batch fermentation of Clostridium acetobutylicum ATCC 824, there is a spontaneous large-scale autolysis phenomenon with significant decrease of cell density immediately after exponential phase. To unravel the role of autolysis, an autolysin-coding gene, CA_C0554, was disrupted by using ClosTron system to obtain the mutant C. acetobutylicum lyc::int(72. The lower final cell density and faster cell density decrease rate of C. acetobutylicum ATCC 824 than those of C. acetobutylicum lyc::int(72 indicates that CA_C0554 was an important but not the sole autolysin-coding gene responding for the large-scale autolysis. Similar glucose utilization and solvents production but obvious lower cell density of C. acetobutylicum ATCC 824 comparing to C. acetobutylicum lyc::int(72 suggests that lysed C. acetobutylicum ATCC 824 cells were metabolic inactive. On the contrary, the spore density of C. acetobutylicum ATCC 824 is 26.1% higher than that of C. acetobutylicum lyc::int(72 in the final culture broth of batch fermentation. We speculated that spontaneous autolysis of metabolic-inactive cells provided nutrients for the sporulating cells. The present study suggests that one important biological role of spontaneous large-scale autolysis in C. acetobutylicum ATCC 824 batch fermentation is contributing to generation of more spores during sporulation.

Spontaneous large-scale autolysis in Clostridium acetobutylicum contributes to generation of more spores.

Science.gov (United States)

Liu, Zhen; Qiao, Kai; Tian, Lei; Zhang, Quan; Liu, Zi-Yong; Li, Fu-Li

2015-01-01

Autolysis is a widespread phenomenon in bacteria. In batch fermentation of Clostridium acetobutylicum ATCC 824, there is a spontaneous large-scale autolysis phenomenon with significant decrease of cell density immediately after exponential phase. To unravel the role of autolysis, an autolysin-coding gene, CA_C0554, was disrupted by using ClosTron system to obtain the mutant C. acetobutylicum lyc::int(72). The lower final cell density and faster cell density decrease rate of C. acetobutylicum ATCC 824 than those of C. acetobutylicum lyc::int(72) indicates that CA_C0554 was an important but not the sole autolysin-coding gene responding for the large-scale autolysis. Similar glucose utilization and solvents production but obvious lower cell density of C. acetobutylicum ATCC 824 comparing to C. acetobutylicum lyc::int(72) suggests that lysed C. acetobutylicum ATCC 824 cells were metabolic inactive. On the contrary, the spore density of C. acetobutylicum ATCC 824 is 26.1% higher than that of C. acetobutylicum lyc::int(72) in the final culture broth of batch fermentation. We speculated that spontaneous autolysis of metabolic-inactive cells provided nutrients for the sporulating cells. The present study suggests that one important biological role of spontaneous large-scale autolysis in C. acetobutylicum ATCC 824 batch fermentation is contributing to generation of more spores during sporulation.

Mutations in the GABA Transporter SLC6A1 Cause Epilepsy with Myoclonic-Atonic Seizures

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Carvill, Gemma L.; McMahon, Jacinta M.; Schneider, Amy; Zemel, Matthew; Myers, Candace T.; Saykally, Julia; Nguyen, John; Robbiano, Angela; Zara, Federico; Specchio, Nicola; Mecarelli, Oriano; Smith, Robert L.; Leventer, Richard J.; Møller, Rikke S.; Nikanorova, Marina; Dimova, Petia; Jordanova, Albena; Petrou, Steven; Helbig, Ingo; Striano, Pasquale; Weckhuysen, Sarah; Berkovic, Samuel F.; Scheffer, Ingrid E.; Mefford, Heather C.

2015-01-01

GAT-1, encoded by SLC6A1, is one of the major gamma-aminobutyric acid (GABA) transporters in the brain and is responsible for re-uptake of GABA from the synapse. In this study, targeted resequencing of 644 individuals with epileptic encephalopathies led to the identification of six SLC6A1 mutations in seven individuals, all of whom have epilepsy with myoclonic-atonic seizures (MAE). We describe two truncations and four missense alterations, all of which most likely lead to loss of function of GAT-1 and thus reduced GABA re-uptake from the synapse. These individuals share many of the electrophysiological properties of Gat1-deficient mice, including spontaneous spike-wave discharges. Overall, pathogenic mutations occurred in 6/160 individuals with MAE, accounting for ∼4% of unsolved MAE cases. PMID:25865495

Sequence analysis of LACI mutations obtained from lung cells of control and radon-exposed Big Blue trademark transgenic mice

International Nuclear Information System (INIS)

Jostes, R.F.; Cross, F.T.; Stillwell, L.

1995-01-01

We have exposed Stratagene Big Blue trademark transgenic mice by inhalation to 310, 640 and 960 Working Level Months (WLM) of radon progency. Twelve LacI mutations have been isolated from the lung tissue of a mouse from the 960-WLM group and the LacI gene sequenced. Mutations are scored only if they occur unambiguously in both strands of the mutant gene; the entire gene is evaluated. In addition, sixteen LacI mutations were isolated from the lung tissue of a mouse from the 640-WLM group; seven have been completely sequenced. Nine LacI mutations from the lung tissue of unirradiated control mice have been sequenced. Sequence data from the unirradiated mice are similar to that found in lung tissue at Stratagene; predominately G:C to A:T transitions in the protein associated region. The mutation spectrum from radon-irradiated mice is markedly different from that obtained with the control, unirradiated mice. Small deletions and insertions compromise 53% of the mutations in the irradiated mice. No multiple events have been noted in the spontaneous mutations; six of the mutations obtained from radon-irradiated mice (26%) have multiple events within the gene. In some, deletions, insertions are base changes occur together. The mutational events in the irradiated mice are approximately equally distributed throughout the gene. The breakpoint rejoining regions of large deletions obtained from the radon-irradiated mice are being studied at the University of California, San Francisco

Modification of mutation frequency in Saccharomyces Cerevisiae

International Nuclear Information System (INIS)

Vashishat, R.K.; Kakar, S.N.

1976-01-01

In a reverse mutation system, using haploid, histidine-requirinq strain of Saccharomyces cerevisiae, the frequency of uv-induced prototrophs increased if the post-irradiation minimal medium was supplemented with limited amounts of histidine. Addition of natural amino acids or RNA bases in the post-irradiation minimal medium, with or without histidine, also increased the uv-induced mutation frequency. Thus, post-irradiation conditions favouring protein and RNA synthesis, are effective in increasing uv-induced mutations in yeast. As compared to uv light, nitrous acid was more effective in inducing reversions in this strain and the frequency increased if the treated cells were plated on minimal medium supplemented with limited amounts of histidine. However, the addition of amino acids or RNA bases decreased the number of revertants. An additional inclusion of histidine reversed the suppressive effect of these metabolites. The mutation induction processes are thus different or differently modifiable in uv and nitrous acid. (author)

Spontaneous recombinase activity of Cre-ERT2 in vivo.

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Kristianto, Jasmin; Johnson, Michael G; Zastrow, Ryley K; Radcliff, Abigail B; Blank, Robert D

2017-06-01

Inducible Cre-ERT recombinase technology is widely used for gene targeting studies. The second generation of inducible Cre-ERT recombinase, hemizygous B6.129S-Tg(UBC-cre/ERT2)1Ejb/J (hereafter abbreviated as Cre-ERT2), a fusion of a mutated estrogen receptor and Cre recombinase, was engineered to be more efficient and specific than the original Cre-ERT. The putative mechanism of selective Cre-mediated recombination is Cre sequestration in the cytoplasm in the basal state with translocation to the nucleus only in the presence of tamoxifen. We utilized both a reporter mouse (B6.129 (Cg)-Gt(ROSA)26Sor tm4(ACTB-tdTomato,-EGFP)Luo /J) and endothelin converting enzyme-1 floxed transgenic mouse line to evaluate Cre-ERT2 activity. We observed spontaneous Cre activity in both settings. Unintended Cre activity is a confounding factor that has a potentially large impact on data interpretation. Thus, it is important to consider background Cre activity in experimental design.

Spontaneous tension haemopneumothorax

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Itam Sarah

2008-10-01

Full Text Available Abstract We present a patient with sudden onset progressive shortness of breath and no history of trauma, who rapidly became haemodynamically compromised with a pneumothorax and pleural effusion seen on chest radiograph. He was treated for spontaneous tension pneumothorax but this was soon revealed to be a tension haemopneumothorax. He underwent urgent thoracotomy after persistent bleeding to explore an apical vascular abnormality seen on CT scanning. To our knowledge this is the first such case reported. Aetiology and current approach to spontaneous haemothorax are discussed briefly.

An Activin Receptor IA/Activin-Like Kinase-2 (R206H Mutation in Fibrodysplasia Ossificans Progressiva

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Rafael Herrera-Esparza

2013-01-01

Full Text Available Fibrodysplasia ossificans progressiva (FOP is an exceptionally rare genetic disease that is characterised by congenital malformations of the great toes and progressive heterotopic ossification (HO in specific anatomical areas. This disease is caused by a mutation in activin receptor IA/activin-like kinase-2 (ACVR1/ALK2. A Mexican family with one member affected by FOP was studied. The patient is a 19-year-old female who first presented with symptoms of FOP at 8 years old; she developed spontaneous and painful swelling of the right scapular area accompanied by functional limitation of movement. Mutation analysis was performed in which genomic DNA as PCR amplified using primers flanking exons 4 and 6, and PCR products were digested with Cac8I and HphI restriction enzymes. The most informative results were obtained with the exon 4 flanking primers and the Cac8I restriction enzyme, which generated a 253 bp product that carries the ACVR1 617G>A mutation, which causes an amino acid substitution of histidine for arginine at position 206 of the glycine-serine (GS domain, and its mutation results in the dysregulation of bone morphogenetic protein (BMP signalling that causes FOP.

Influence of inhibitors of poly(ADP-ribose) polymerase on DNA repair, chromosomal alterations, and mutations

Energy Technology Data Exchange (ETDEWEB)

Natarajan, A.T.; van Zeeland, A.A.; Zwanenburg, T.S.

1983-01-01

The influence of inhibitors of poly(ADP-ribose) polymerase such as 3-aminobenzamide (3AB) and benzamide (B) on the spontaneously occurring as well as mutagen induced chromosomal aberrations, sister chromatid exchanges (SCEs) and point mutations has been studied. In addition, the influence of 3AB on DNA repair was measured following treatment with physical and chemical mutagens. Post treatment of X-irradiated mammalian cells with 3AB increases the frequencies of induced chromosomal aberrations by a factor of 2 to 3. 3AB, when present in the medium containing bromodeoxyuridine(BrdUrd) during two cell cycles, increases the frequencies of SCEs in Chinese hamster ovary cells (CHO) in a concentration dependent manner leading to about a 10-fold increase at 10 mM concentration. The extent of increase in the frequencies of SCEs due to 1 mM 3AB in several human cell lines has been studied, including those derived from patients suffering from genetic diseases such as ataxia telangiectasia (A-T), Fanconi's anemia (FA), and Huntington's chorea. None of these syndromes showed any increased response when compared to normal cells. 3AB, however, increased the frequencies of spontaneously occurring chromosomal aberrations in A-T and FA cells. 3AB does not influence the frequencies of SCEs induced by UV or mitomycin C (MMC) in CHO cells. However, it increases the frequencies of SCEs induced by ethyl methanesulfonate (EMS) and methyl methanesulfonate (MMS). Under the conditions in which 3AB increases the frequencies of spontaneously occurring as well as induced SCEs, it does not increase the frequencies of point mutations in hypoxanthine-guanine phosphoribosyltransferase (HGPRT) locus. 3AB does not influence the amount of repair replication following dimethylsulphate (DMS) treatment of human fibroblasts, or UV irradiated human lymphocytes.

Spontaneous compactification to homogeneous spaces

International Nuclear Information System (INIS)

Mourao, J.M.

1988-01-01

The spontaneous compactification of extra dimensions to compact homogeneous spaces is studied. The methods developed within the framework of coset space dimensional reduction scheme and the most general form of invariant metrics are used to find solutions of spontaneous compactification equations

Influence of preirradiation history of E. coli WP2 cells on the residual fixation of mutations in rpsL. (strA) locus

Energy Technology Data Exchange (ETDEWEB)

Filippov, V D

1986-07-01

The values of residual fixation of strA mutations in E.coli culture, irradiated by UV-light (6.8 J/m/sup 2/) in different physiological states and conforming to different in depth strA mutation frequency decrease in postirradiation incubation under conditions unfavourable for protein synthesis are determined. By residual fixation one should mean accumulation of strA mutations stable to antimutagenous effect of photoreactivating light in cell population incubated in buffer after UV radiation. It is established that residual fixation is small in cultures, conforming to deep decrease, and is a factor (about 40% of strA mutations is fixed) in a culture, conforming to moderate decrease (about 60% of strA mutations disappears) of mutation frequency in incubation under conditions unfavourable for protein synthesis. The conclusion is made that the depth of strA mutation frequency decrease, taking place under the influence of mfd system, depends on the level of residual fixation of this mutations. It is supposed that residual fixation is caused by rpsL (strA) locus introduction in replication cycle initiated after radiation.

Spontaneous Rotation of a Toric Implantable Collamer Lens

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Alejandro Navas

2010-11-01

Full Text Available We present a case of toric implantable collamer lens (TICL spontaneous rotation in a patient with myopic astigmatism. A 23-year-old female underwent TICL implantation. Preoperative uncorrected visual acuity (UCVA was 20/800 and 20/1200, respectively, with –7.75 –4.25 × 0° and –8.25 –5.25 × 180°. The left eye achieved an UCVA of 20/30. After 3 months of successful implantation of TICL in the left eye, the patient presented with a sudden decrease in visual acuity in the left eye. UCVA was 20/100 with a refraction of +2.50 –4.50 × 165°. We observed the toric marks with a 30° rotation from the original position and decided to reposition the TICL, obtaining a final UCVA of 20/25, which remained stable at 6 months’ follow-up. TICL can present a considerable rotation that compromises visual acuity. The relocation of TICL is a safe and effective procedure to recover visual acuity due to significant spontaneous TICL rotation.

Genome-wide analysis of mutations in mutant lineages selected following fast-neutron irradiation mutagenesis of Arabidopsis thaliana

KAUST Repository

Belfield, E.J.; Gan, X.; Mithani, A.; Brown, C.; Jiang, C.; Franklin, K.; Alvey, E.; Wibowo, A.; Jung, M.; Bailey, K.; Kalwani, S.; Ragoussis, J.; Mott, R.; Harberd, N.P.

2012-01-01

Ionizing radiation has long been known to induce heritable mutagenic change in DNA sequence. However, the genome-wide effect of radiation is not well understood. Here we report the molecular properties and frequency of mutations in phenotypically selected mutant lines isolated following exposure of the genetic model flowering plant Arabidopsis thaliana to fast neutrons (FNs). Previous studies suggested that FNs predominantly induce deletions longer than a kilobase in A. thaliana. However, we found a higher frequency of single base substitution than deletion mutations. While the overall frequency and molecular spectrum of fast-neutron (FN)-induced single base substitutions differed substantially from those of "background" mutations arising spontaneously in laboratory-grown plants, G:C>A:T transitions were favored in both. We found that FN-induced G:C>A:T transitions were concentrated at pyrimidine dinucleotide sites, suggesting that FNs promote the formation of mutational covalent linkages between adjacent pyrimidine residues. In addition, we found that FNs induced more single base than large deletions, and that these single base deletions were possibly caused by replication slippage. Our observations provide an initial picture of the genome-wide molecular profile of mutations induced in A. thaliana by FN irradiation and are particularly informative of the nature and extent of genome-wide mutation in lines selected on the basis of mutant phenotypes from FN-mutagenized A. thaliana populations.

Genome-wide analysis of mutations in mutant lineages selected following fast-neutron irradiation mutagenesis of Arabidopsis thaliana

KAUST Repository

Belfield, E.J.

2012-04-12

Ionizing radiation has long been known to induce heritable mutagenic change in DNA sequence. However, the genome-wide effect of radiation is not well understood. Here we report the molecular properties and frequency of mutations in phenotypically selected mutant lines isolated following exposure of the genetic model flowering plant Arabidopsis thaliana to fast neutrons (FNs). Previous studies suggested that FNs predominantly induce deletions longer than a kilobase in A. thaliana. However, we found a higher frequency of single base substitution than deletion mutations. While the overall frequency and molecular spectrum of fast-neutron (FN)-induced single base substitutions differed substantially from those of "background" mutations arising spontaneously in laboratory-grown plants, G:C>A:T transitions were favored in both. We found that FN-induced G:C>A:T transitions were concentrated at pyrimidine dinucleotide sites, suggesting that FNs promote the formation of mutational covalent linkages between adjacent pyrimidine residues. In addition, we found that FNs induced more single base than large deletions, and that these single base deletions were possibly caused by replication slippage. Our observations provide an initial picture of the genome-wide molecular profile of mutations induced in A. thaliana by FN irradiation and are particularly informative of the nature and extent of genome-wide mutation in lines selected on the basis of mutant phenotypes from FN-mutagenized A. thaliana populations.

Mechanism of f-decay - spontaneous emission of fragments by heavy nuclei

International Nuclear Information System (INIS)

Rubchenya, V.A.; Ehjsmont, V.P.; Yavshits, S.G.

1987-01-01

A new type of model of radioactive decay - spontaneous emission of fragments by heavy nuclei, for which f-decay has been suggested, is formulated. The consideration is based on representation about a disintegrating configuration, for which the probability of f-cluster formation is close to 1. The moments method is used to determine the parameters of the disintegrating configuration. The probability of disintegrating configuration formation is determined by collective properties of a disintegrating nucleus. Effect of nucleon shells of the daughter nucleus and fragment leads to more compact disintegrating configuration and to decay energy increase, that's why at f-decay magic nuclei are formed. Probable spontaneous f-decay values calculated agree satisfactorily with experimental data. The calculational results testify to considerable decrease of f-decay probability at Z≥94

Involvement of hippocampal NMDA receptors in retrieval of spontaneous object recognition memory in rats.

Science.gov (United States)

Iwamura, Etsushi; Yamada, Kazuo; Ichitani, Yukio

2016-07-01

The involvement of hippocampal N-methyl-d-aspartate (NMDA) receptors in the retrieval process of spontaneous object recognition memory was investigated. The spontaneous object recognition test consisted of three phases. In the sample phase, rats were exposed to two identical objects several (2-5) times in the arena. After the sample phase, various lengths of delay intervals (24h-6 weeks) were inserted (delay phase). In the test phase in which both the familiar and the novel objects were placed in the arena, rats' novel object exploration behavior under the hippocampal treatment of NMDA receptor antagonist, AP5, or vehicle was observed. With 5 exposure sessions in the sample phase (experiment 1), AP5 treatment in the test phase significantly decreased discrimination ratio when the delay was 3 weeks but not when it was one week. On the other hand, with 2 exposure sessions in the sample phase (experiment 2) in which even vehicle-injected control animals could not discriminate the novel object from the familiar one with a 3 week delay, AP5 treatment significantly decreased discrimination ratio when the delay was one week, but not when it was 24h. Additional experiment (experiment 3) showed that the hippocampal treatment of an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonist, NBQX, decreased discrimination ratio with all delay intervals tested (24h-3 weeks). Results suggest that hippocampal NMDA receptors play an important role in the retrieval of spontaneous object recognition memory especially when the memory trace weakens. Copyright © 2016. Published by Elsevier B.V.

Spontaneous Intracranial Hypotension without Orthostatic Headache

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Tülay Kansu

2009-03-01

Full Text Available We report 2 cases of spontaneous intracranial hypotension that presented with unilateral abducens nerve palsy, without orthostatic headache. While sixth nerve palsies improved without any intervention, subdural hematoma was detected with magnetic resonance imaging. We conclude that headache may be absent in spontaneous intracranial hypotension and spontaneous improvement of sixth nerve palsy can occur, even after the development of a subdural hematoma

Bactobolin resistance is conferred by mutations in the L2 ribosomal protein.

Science.gov (United States)

Chandler, Josephine R; Truong, Thao T; Silva, Patricia M; Seyedsayamdost, Mohammad R; Carr, Gavin; Radey, Matthew; Jacobs, Michael A; Sims, Elizabeth H; Clardy, Jon; Greenberg, E Peter

2012-12-18

Burkholderia thailandensis produces a family of polyketide-peptide molecules called bactobolins, some of which are potent antibiotics. We found that growth of B. thailandensis at 30°C versus that at 37°C resulted in increased production of bactobolins. We purified the three most abundant bactobolins and determined their activities against a battery of bacteria and mouse fibroblasts. Two of the three compounds showed strong activities against both bacteria and fibroblasts. The third analog was much less potent in both assays. These results suggested that the target of bactobolins might be conserved across bacteria and mammalian cells. To learn about the mechanism of bactobolin activity, we isolated four spontaneous bactobolin-resistant Bacillus subtilis mutants. We used genomic sequencing technology to show that each of the four resistant variants had mutations in rplB, which codes for the 50S ribosome-associated L2 protein. Ectopic expression of a mutant rplB gene in wild-type B. subtilis conferred bactobolin resistance. Finally, the L2 mutations did not confer resistance to other antibiotics known to interfere with ribosome function. Our data indicate that bactobolins target the L2 protein or a nearby site and that this is not the target of other antibiotics. We presume that the mammalian target of bactobolins involves the eukaryotic homolog of L2 (L8e). Currently available antibiotics target surprisingly few cellular functions, and there is a need to identify novel antibiotic targets. We have been interested in the Burkholderia thailandensis bactobolins, and we sought to learn about the target of bactobolin activity by mapping spontaneous resistance mutations in the bactobolin-sensitive Bacillus subtilis. Our results indicate that the bactobolin target is the 50S ribosome-associated L2 protein or a region of the ribosome affected by L2. Bactobolin-resistant mutants are not resistant to other known ribosome inhibitors. Our evidence indicates that bactobolins

Spontaneous intraorbital hematoma: case report

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Vinodan Paramanathan

2010-12-01

Full Text Available Vinodan Paramanathan, Ardalan ZolnourianQueen's Hospital NHS Foundation Trust, Burton on Trent, Staffordshire DE13 0RB, UKAbstract: Spontaneous intraorbital hematoma is an uncommon clinical entity seen in ophthalmology practice. It is poorly represented in the literature. Current evidence attributes it to orbital trauma, neoplasm, vascular malformations, acute sinusitis, and systemic abnormalities. A 65-year-old female presented with spontaneous intraorbital hematoma manifesting as severe ocular pains, eyelid edema, proptosis, and diplopia, without a history of trauma. Computer tomography demonstrated a fairly well defined extraconal lesion with opacification of the paranasal sinuses. The principal differential based on all findings was that of a spreading sinus infection and an extraconal tumor. An unprecedented finding of a spontaneous orbital hematoma was discovered when the patient was taken to theater. We discuss the rarity of this condition and its management.Keywords: hemorrhage, ophthalmology, spontaneous, intra-orbital, hematoma

Suppression of the Escherichia coli ssb-1 mutation by an allele of groEL.

OpenAIRE

Ruben, S M; VanDenBrink-Webb, S E; Rein, D C; Meyer, R R

1988-01-01

A series of spontaneous suppressors to the temperature-sensitive phenotype of the single-stranded DNA-binding protein mutation ssb-1 were isolated. A genomic library of EcoRI fragments from one of these suppressor strains was prepared by using pBR325 as the cloning vector. A 10.0-kilobase class of inserts was identified as carrying the ssb-1 gene itself. A second class of 8.3-kilobase inserts was shown to contain the groE region by (i) restriction analysis, (ii) Southern hybridization of the ...

Finding cancer driver mutations in the era of big data research.

Science.gov (United States)

Poulos, Rebecca C; Wong, Jason W H

2018-04-02

In the last decade, the costs of genome sequencing have decreased considerably. The commencement of large-scale cancer sequencing projects has enabled cancer genomics to join the big data revolution. One of the challenges still facing cancer genomics research is determining which are the driver mutations in an individual cancer, as these contribute only a small subset of the overall mutation profile of a tumour. Focusing primarily on somatic single nucleotide mutations in this review, we consider both coding and non-coding driver mutations, and discuss how such mutations might be identified from cancer sequencing datasets. We describe some of the tools and database that are available for the annotation of somatic variants and the identification of cancer driver genes. We also address the use of genome-wide variation in mutation load to establish background mutation rates from which to identify driver mutations under positive selection. Finally, we describe the ways in which mutational signatures can act as clues for the identification of cancer drivers, as these mutations may cause, or arise from, certain mutational processes. By defining the molecular changes responsible for driving cancer development, new cancer treatment strategies may be developed or novel preventative measures proposed.

Mutation rate heterogeneity and the generation of allele diversity at the human minisatellite MS205 (D16S309).

Science.gov (United States)

May, C A; Jeffreys, A J; Armour, J A

1996-11-01

Many tandemly repeated minisatellite loci display extreme levels of length variation as a consequence of high rates of spontaneous germline mutation altering repeat copy number. Direct screening for new allele lengths by small-pool PCR has shown that instability at the human minisatellite locus MS205 (D16S309) is largely germline specific and usually results in the gain or loss of just a few repeat units. Structural analysis of the order of variant repeats has shown that these events occur preferentially at one end of the tandem array and can result in complex rearrangements including the inter-allelic transfer of repeat units. In contrast, putative mutants recovered from somatic DNA occur at a substantially lower rate and are simple and non-polar in nature. Germline mutation rates vary considerably between alleles, consistent with regulation occurring in cis. Although examination of DNA sequence polymorphisms immediately flanking the minisatellite reveals no definitive associations with germline mutation rate variation, differences in rate may be paralleled by changes in mutation spectrum. These findings help to explain the diversity of MS205 allele structures in modern humans and suggest a common mutation pathway with some other minisatellites.

Vision drives correlated activity without patterned spontaneous activity in developing Xenopus retina.

Science.gov (United States)

Demas, James A; Payne, Hannah; Cline, Hollis T

2012-04-01

Developing amphibians need vision to avoid predators and locate food before visual system circuits fully mature. Xenopus tadpoles can respond to visual stimuli as soon as retinal ganglion cells (RGCs) innervate the brain, however, in mammals, chicks and turtles, RGCs reach their central targets many days, or even weeks, before their retinas are capable of vision. In the absence of vision, activity-dependent refinement in these amniote species is mediated by waves of spontaneous activity that periodically spread across the retina, correlating the firing of action potentials in neighboring RGCs. Theory suggests that retinorecipient neurons in the brain use patterned RGC activity to sharpen the retinotopy first established by genetic cues. We find that in both wild type and albino Xenopus tadpoles, RGCs are spontaneously active at all stages of tadpole development studied, but their population activity never coalesces into waves. Even at the earliest stages recorded, visual stimulation dominates over spontaneous activity and can generate patterns of RGC activity similar to the locally correlated spontaneous activity observed in amniotes. In addition, we show that blocking AMPA and NMDA type glutamate receptors significantly decreases spontaneous activity in young Xenopus retina, but that blocking GABA(A) receptor blockers does not. Our findings indicate that vision drives correlated activity required for topographic map formation. They further suggest that developing retinal circuits in the two major subdivisions of tetrapods, amphibians and amniotes, evolved different strategies to supply appropriately patterned RGC activity to drive visual circuit refinement. Copyright © 2011 Wiley Periodicals, Inc.

Germline mutation in RNASEL predicts increased risk of head and neck, uterine cervix and breast cancer.

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Bo Eskerod Madsen

Full Text Available UNLABELLED: THE BACKGROUND: Ribonuclease L (RNASEL, encoding the 2'-5'-oligoadenylate (2-5A-dependent RNase L, is a key enzyme in the interferon induced antiviral and anti-proliferate pathway. Mutations in RNASEL segregate with the disease in prostate cancer families and specific genotypes are associated with an increased risk of prostate cancer. Infection by human papillomavirus (HPV is the major risk factor for uterine cervix cancer and for a subset of head and neck squamous cell carcinomas (HNSCC. HPV, Epstein Barr virus (EBV and sequences from mouse mammary tumor virus (MMTV have been detected in breast tumors, and the presence of integrated SV40 T/t antigen in breast carcinomas correlates with an aggressive phenotype and poor prognosis. A genetic predisposition could explain why some viral infections persist and induce cancer, while others disappear spontaneously. This points at RNASEL as a strong susceptibility gene. METHODOLOGY/PRINCIPAL FINDINGS: To evaluate the implication of an abnormal activity of RNase L in the onset and development of viral induced cancers, the study was initiated by searching for germline mutations in patients diagnosed with uterine cervix cancer. The rationale behind is that close to 100% of the cervix cancer patients have a persistent HPV infection, and if a defective RNase L were responsible for the lack of ability to clear the HPV infection, we would expect to find a wide spectrum of mutations in these patients, leading to a decreased RNase L activity. The HPV genotype was established in tumor DNA from 42 patients diagnosed with carcinoma of the uterine cervix and somatic tissue from these patients was analyzed for mutations by direct sequencing of all coding and regulatory regions of RNASEL. Fifteen mutations, including still uncharacterized, were identified. The genotype frequencies of selected single nucleotide polymorphisms (SNPs established in the cervix cancer patients were compared between 382 patients

Common Β- Thalassaemia Mutations in

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P Azarfam

2005-01-01

Full Text Available Introduction: β –Thalassaemia was first explained by Thomas Cooly as Cooly’s anaemia in 1925. The β- thalassaemias are hereditary autosomal disorders with decreased or absent β-globin chain synthesis. The most common genetic defects in β-thalassaemias are caused by point mutations, micro deletions or insertions within the β-globin gene. Material and Methods: In this research , 142 blood samples (64 from childrens hospital of Tabriz , 15 samples from Shahid Gazi hospital of Tabriz , 18 from Urumia and 45 samples from Aliasghar hospital of Ardebil were taken from thalassaemic patients (who were previously diagnosed .Then 117 non-familial samples were selected . The DNA of the lymphocytes of blood samples was extracted by boiling and Proteinase K- SDS procedure, and mutations were detected by ARMS-PCR methods. Results: From the results obtained, eleven most common mutations,most of which were Mediterranean mutations were detected as follows; IVS-I-110(G-A, IVS-I-1(G-A ،IVS-I-5(G-C ,Frameshift Codon 44 (-C,( codon5(-CT,IVS-1-6(T-C, IVS-I-25(-25bp del ,Frameshift 8.9 (+G ,IVS-II-1(G-A ,Codon 39(C-T, Codon 30(G-C the mutations of the samples were defined. The results showed that Frameshift 8.9 (+G, IVS-I-110 (G-A ,IVS-II-I(G-A, IVS-I-5(G-C, IVS-I-1(G-A , Frameshift Codon 44(-C , codon5(-CT , IVS-1-6(T-C , IVS-I-25(-25bp del with a frequency of 29.9%, 25.47%,17.83%, 7.00%, 6.36% , 6.63% , 3.8% , 2.5% , 0.63% represented the most common mutations in North - west Iran. No mutations in Codon 39(C-T and Codon 30(G-C were detected. Cunclusion: The frequency of the same mutations in patients from North - West of Iran seems to be different as compared to other regions like Turkey, Pakistan, Lebanon and Fars province of Iran. The pattern of mutations in this region is more or less the same as in the Mediterranean region, but different from South west Asia and East Asia.

Screening for spontaneous preterm birth

NARCIS (Netherlands)

van Os, M.A.; van Dam, A.J.E.M.

2015-01-01

Preterm birth is the most important cause of perinatal morbidity and mortality worldwide. In this thesis studies on spontaneous preterm birth are presented. The main objective was to investigate the predictive capacity of mid-trimester cervical length measurement for spontaneous preterm birth in a

Spontaneous breaking of time-reversal symmetry in strongly interacting two-dimensional electron layers in silicon and germanium.

Science.gov (United States)

Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A

2014-06-13

We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.

Spontaneous mutation of Dock7 results in lower trabecular bone mass and impaired periosteal expansion in aged female Misty mice.

Science.gov (United States)

Le, Phuong T; Bishop, Kathleen A; Maridas, David E; Motyl, Katherine J; Brooks, Daniel J; Nagano, Kenichi; Baron, Roland; Bouxsein, Mary L; Rosen, Clifford J

2017-12-01

Misty mice (m/m) have a loss of function mutation in Dock7 gene, a guanine nucleotide exchange factor, resulting in low bone mineral density, uncoupled bone remodeling and reduced bone formation. Dock7 has been identified as a modulator of osteoblast number and in vitro osteogenic differentiation in calvarial osteoblast culture. In addition, m/m exhibit reduced preformed brown adipose tissue innervation and temperature as well as compensatory increase in beige adipocyte markers. While the low bone mineral density phenotype is in part due to higher sympathetic nervous system (SNS) drive in young mice, it is unclear what effect aging would have in mice homozygous for the mutation in the Dock7 gene. We hypothesized that age-related trabecular bone loss and periosteal envelope expansion would be altered in m/m. To test this hypothesis, we comprehensively characterized the skeletal phenotype of m/m at 16, 32, 52, and 78wks of age. When compared to age-matched wild-type control mice (+/+), m/m had lower areal bone mineral density (aBMD) and areal bone mineral content (aBMC). Similarly, both femoral and vertebral BV/TV, Tb.N, and Conn.D were decreased in m/m while there was also an increase in Tb.Sp. As low bone mineral density and decreased trabecular bone were already present at 16wks of age in m/m and persisted throughout life, changes in age-related trabecular bone loss were not observed highlighting the role of Dock7 in controlling trabecular bone acquisition or bone loss prior to 16wks of age. Cortical thickness was also lower in the m/m across all ages. Periosteal and endosteal circumferences were higher in m/m compared to +/+ at 16wks. However, endosteal and periosteal expansion were attenuated in m/m, resulting in m/m having lower periosteal and endosteal circumferences by 78wks of age compared to +/+, highlighting the critical role of Dock7 in appositional bone expansion. Histomorphometry revealed that osteoblasts were nearly undetectable in m/m and marrow

Spontaneous baroreflex sensitivity estimates during graded bicycle exercise: a comparative study

International Nuclear Information System (INIS)

Vallais, Frederic; Baselli, Giuseppe; Lucini, Daniela; Pagani, Massimo; Porta, Alberto

2009-01-01

In the literature, several methods have been proposed for the assessment of the baroreflex sensitivity from spontaneous variability of heart period and systolic arterial pressure. The present study compares the most utilized approaches for the evaluation of the spontaneous baroreflex sensitivity (i.e. sequence-based, spectral, cross-spectral and model-based techniques) over a protocol capable of inducing a progressive decrease of the baroreflex sensitivity in the presence of a relevant respiratory drive (i.e. a stepwise dynamic bicycle exercise at 10%, 20% and 30% of the maximum nominal individual effort) in 16 healthy humans. Results demonstrated that the degree of correlation among the estimates is related to the structure of the model explicitly or implicitly assumed by the method and depends on the experimental condition (i.e. on the physiological mechanisms contemporaneously active with baroreflex, e.g. cardiopulmonary reflexes). However, even in the presence of a significant correlation, proportional and/or constant biases can be present, thus rendering spontaneous baroreflex estimates not interchangeable. We suggest that the comparison among different baroreflex sensitivity estimates might elucidate physiological mechanisms responsible for the relationship between heart period and systolic arterial pressure

Kv1.1 knock-in ataxic mice exhibit spontaneous myokymic activity exacerbated by fatigue, ischemia and low temperature.

Science.gov (United States)

Brunetti, Orazio; Imbrici, Paola; Botti, Fabio Massimo; Pettorossi, Vito Enrico; D'Adamo, Maria Cristina; Valentino, Mario; Zammit, Christian; Mora, Marina; Gibertini, Sara; Di Giovanni, Giuseppe; Muscat, Richard; Pessia, Mauro

2012-09-01

Episodic ataxia type 1 (EA1) is an autosomal dominant neurological disorder characterized by myokymia and attacks of ataxic gait often precipitated by stress. Several genetic mutations have been identified in the Shaker-like K(+) channel Kv1.1 (KCNA1) of EA1 individuals, including V408A, which result in remarkable channel dysfunction. By inserting the heterozygous V408A, mutation in one Kv1.1 allele, a mouse model of EA1 has been generated (Kv1.1(V408A/+)). Here, we investigated the neuromuscular transmission of Kv1.1(V408A/+) ataxic mice and their susceptibility to physiologically relevant stressors. By using in vivo preparations of lateral gastrocnemius (LG) nerve-muscle from Kv1.1(+/+) and Kv1.1(V408A/+) mice, we show that the mutant animals exhibit spontaneous myokymic discharges consisting of repeated singlets, duplets or multiplets, despite motor nerve axotomy. Two-photon laser scanning microscopy from the motor nerve, ex vivo, revealed spontaneous Ca(2+) signals that occurred abnormally only in preparations dissected from Kv1.1(V408A/+) mice. Spontaneous bursting activity, as well as that evoked by sciatic nerve stimulation, was exacerbated by muscle fatigue, ischemia and low temperatures. These stressors also increased the amplitude of compound muscle action potential. Such abnormal neuromuscular transmission did not alter fiber type composition, neuromuscular junction and vascularization of LG muscle, analyzed by light and electron microscopy. Taken together these findings provide direct evidence that identifies the motor nerve as an important generator of myokymic activity, that dysfunction of Kv1.1 channels alters Ca(2+) homeostasis in motor axons, and also strongly suggest that muscle fatigue contributes more than PNS fatigue to exacerbate the myokymia/neuromyotonia phenotype. More broadly, this study points out that juxtaparanodal K(+) channels composed of Kv1.1 subunits exert an important role in dampening the excitability of motor nerve axons during

Early pregnancy angiogenic markers and spontaneous abortion

DEFF Research Database (Denmark)

Andersen, Louise B; Dechend, Ralf; Karumanchi, S Ananth

2016-01-01

BACKGROUND: Spontaneous abortion is the most commonly observed adverse pregnancy outcome. The angiogenic factors soluble Fms-like kinase 1 and placental growth factor are critical for normal pregnancy and may be associated to spontaneous abortion. OBJECTIVE: We investigated the association between...... maternal serum concentrations of soluble Fms-like kinase 1 and placental growth factor, and subsequent spontaneous abortion. STUDY DESIGN: In the prospective observational Odense Child Cohort, 1676 pregnant women donated serum in early pregnancy, gestational week ..., interquartile range 71-103). Concentrations of soluble Fms-like kinase 1 and placental growth factor were determined with novel automated assays. Spontaneous abortion was defined as complete or incomplete spontaneous abortion, missed abortion, or blighted ovum

Somatic Mutations and Clonal Hematopoiesis in Aplastic Anemia.

Science.gov (United States)

Yoshizato, Tetsuichi; Dumitriu, Bogdan; Hosokawa, Kohei; Makishima, Hideki; Yoshida, Kenichi; Townsley, Danielle; Sato-Otsubo, Aiko; Sato, Yusuke; Liu, Delong; Suzuki, Hiromichi; Wu, Colin O; Shiraishi, Yuichi; Clemente, Michael J; Kataoka, Keisuke; Shiozawa, Yusuke; Okuno, Yusuke; Chiba, Kenichi; Tanaka, Hiroko; Nagata, Yasunobu; Katagiri, Takamasa; Kon, Ayana; Sanada, Masashi; Scheinberg, Phillip; Miyano, Satoru; Maciejewski, Jaroslaw P; Nakao, Shinji; Young, Neal S; Ogawa, Seishi

2015-07-02

In patients with acquired aplastic anemia, destruction of hematopoietic cells by the immune system leads to pancytopenia. Patients have a response to immunosuppressive therapy, but myelodysplastic syndromes and acute myeloid leukemia develop in about 15% of the patients, usually many months to years after the diagnosis of aplastic anemia. We performed next-generation sequencing and array-based karyotyping using 668 blood samples obtained from 439 patients with aplastic anemia. We analyzed serial samples obtained from 82 patients. Somatic mutations in myeloid cancer candidate genes were present in one third of the patients, in a limited number of genes and at low initial variant allele frequency. Clonal hematopoiesis was detected in 47% of the patients, most frequently as acquired mutations. The prevalence of the mutations increased with age, and mutations had an age-related signature. DNMT3A-mutated and ASXL1-mutated clones tended to increase in size over time; the size of BCOR- and BCORL1-mutated and PIGA-mutated clones decreased or remained stable. Mutations in PIGA and BCOR and BCORL1 correlated with a better response to immunosuppressive therapy and longer and a higher rate of overall and progression-free survival; mutations in a subgroup of genes that included DNMT3A and ASXL1 were associated with worse outcomes. However, clonal dynamics were highly variable and might not necessarily have predicted the response to therapy and long-term survival among individual patients. Clonal hematopoiesis was prevalent in aplastic anemia. Some mutations were related to clinical outcomes. A highly biased set of mutations is evidence of Darwinian selection in the failed bone marrow environment. The pattern of somatic clones in individual patients over time was variable and frequently unpredictable. (Funded by Grant-in-Aid for Scientific Research and others.).

Hyperphosphatemia during spontaneous tumor lysis syndrome culminate in severe hyphosphatemia at the time of blast crisis of Phneg CML to acute myelomoncytic leukemia

Directory of Open Access Journals (Sweden)

Salomon Ophira

2012-08-01

Full Text Available Abstract Extreme swing of phosphor from severe hyperphosphatemia to severe hypophosphatemia in a patient with blast crisis of myeloid origin was the result of imbalance between massive apoptosis of leukemic cells in the context of spontaneous tumor lysis syndrome and massive production of leukemic cells with only 1% of blast in peripheral blood. The mutated p53 protein suggested acting as oncogene in the presented case and possibly affecting phosphor status.

Mutations in valosin-containing protein (VCP) decrease ADP/ATP translocation across the mitochondrial membrane and impair energy metabolism in human neurons.

Science.gov (United States)

Ludtmann, Marthe H R; Arber, Charles; Bartolome, Fernando; de Vicente, Macarena; Preza, Elisavet; Carro, Eva; Houlden, Henry; Gandhi, Sonia; Wray, Selina; Abramov, Andrey Y

2017-05-26

Mutations in the gene encoding valosin-containing protein (VCP) lead to multisystem proteinopathies including frontotemporal dementia. We have previously shown that patient-derived VCP mutant fibroblasts exhibit lower mitochondrial membrane potential, uncoupled respiration, and reduced ATP levels. This study addresses the underlying basis for mitochondrial uncoupling using VCP knockdown neuroblastoma cell lines, induced pluripotent stem cells (iPSCs), and iPSC-derived cortical neurons from patients with pathogenic mutations in VCP Using fluorescent live cell imaging and respiration analysis we demonstrate a VCP mutation/knockdown-induced dysregulation in the adenine nucleotide translocase, which results in a slower rate of ADP or ATP translocation across the mitochondrial membranes. This deregulation can explain the mitochondrial uncoupling and lower ATP levels in VCP mutation-bearing neurons via reduced ADP availability for ATP synthesis. This study provides evidence for a role of adenine nucleotide translocase in the mechanism underlying altered mitochondrial function in VCP-related degeneration, and this new insight may inform efforts to better understand and manage neurodegenerative disease and other proteinopathies. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Decreased expression of lysyl hydroxylase 2 (LH2) in skin fibroblasts from three Ehlers-Danlos patients does not result from mutations in either the coding or proximal promoter region of the LH2 gene.

Science.gov (United States)

Walker, L C; Teebi, A S; Marini, J C; De Paepe, A; Malfait, F; Atsawasuwan, P; Yamauchi, M; Yeowell, H N

2004-12-01

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of inherited connective tissue disorders characterized by tissue fragility, hyperelasticity of the skin and joint hypermobility. This phenotype, accompanied by kyphoscoliosis and/or ocular fragility, is present in patients with the autosomal recessive type VI form of EDS. These patients have significantly decreased levels of lysyl hydroxylase (LH) activity, due to mutations in the LH1 gene. LH hydroxylates specific lysine residues in the collagen molecule that are precursors for the formation of cross-links which provide collagen with its tensile strength. No disorder has been directly linked to decreased expression of LH2 and LH3, two other isoforms of LH. This study describes 3 patients with mixed phenotypes of EDS, who have significantly decreased mRNAs for LH2, but normal levels of LH1 and LH3 mRNAs, in their skin fibroblasts. In contrast to the effect of LH1 deficiency in EDS VI patients, the decreased expression of LH2 does not affect LH activity, bifunctional collagen cross-links (measured after reduction as dihydroxylysinonorleucine (DHLNL) and hydroxylysinonorleucine (HLNL)), or helical lysine hydroxylation in these cell lines. Sequence analysis of full length LH2 cDNAs and 1kb of the promoter region of LH2 does not show mutations that could explain the decreased expression of LH2. These results suggest that the deficiency of LH2 in these fibroblasts may be caused by changes in other factors required for the expression of LH2.

Spontaneous calcium transients in human neural progenitor cells mediated by transient receptor potential channels.

Science.gov (United States)

Morgan, Peter J; Hübner, Rayk; Rolfs, Arndt; Frech, Moritz J

2013-09-15

Calcium signals affect many developmental processes, including proliferation, migration, survival, and apoptosis, processes that are of particular importance in stem cells intended for cell replacement therapies. The mechanisms underlying Ca(2+) signals, therefore, have a role in determining how stem cells respond to their environment, and how these responses might be controlled in vitro. In this study, we examined the spontaneous Ca(2+) activity in human neural progenitor cells during proliferation and differentiation. Pharmacological characterization indicates that in proliferating cells, most activity is the result of transient receptor potential (TRP) channels that are sensitive to Gd(3+) and La(3+), with the more subtype selective antagonist Ruthenium red also reducing activity, suggesting the involvement of transient receptor potential vanilloid (TRPV) channels. In differentiating cells, Gd(3+) and La(3+)-sensitive TRP channels also appear to underlie the spontaneous activity; however, no sub-type-specific antagonists had any effect. Protein levels of TRPV2 and TRPV3 decreased in differentiated cells, which is demonstrated by western blot. Thus, it appears that TRP channels represent the main route of Ca(2+) entry in human neural progenitor cells (hNPCs), but the responsible channel types are subject to substitution under differentiating conditions. The level of spontaneous activity could be increased and decreased by lowering and raising the extracellular K(+) concentration. Proliferating cells in low K(+) slowed the cell cycle, with a disproportionate increased percentage of cells in G1 phase and a reduction in S phase. Taken together, these results suggest a link between external K(+) concentration, spontaneous Ca(2+) transients, and cell cycle distribution, which is able to influence the fate of stem and progenitor cells.

Spontaneous emission by moving atoms

International Nuclear Information System (INIS)

Meystre, P.; Wilkens, M.

1994-01-01

It is well known that spontaneous emission is not an intrinsic atomic property, but rather results from the coupling of the atom to the vacuum modes of the electromagnetic field. As such, it can be modified by tailoring the electromagnetic environment into which the atom can radiate. This was already realized by Purcell, who noted that the spontaneous emission rate can be enhanced if the atom placed inside a cavity is resonant with one of the cavity is resonant with one of the cavity modes, and by Kleppner, who discussed the opposite case of inhibited spontaneous emission. It has also been recognized that spontaneous emission need not be an irreversible process. Indeed, a system consisting of a single atom coupled to a single mode of the electromagnetic field undergoes a periodic exchange of excitation between the atom and the field. This periodic exchange remains dominant as long as the strength of the coupling between the atom and a cavity mode is itself dominant. 23 refs., 6 figs

The influence of preirradiation history of E. coli WP2 cells on the residual fixation of mutations in rpsL. (strA) locus

International Nuclear Information System (INIS)

Filippov, V.D.

1986-01-01

The values of residual fixation of strA mutations in E.coli culture, irradiated by UV-light (6.8 J/m 2 ) in different physiological states and conforming to different in depth strA mutation frequency decrease in postirradiation incubation under conditions unfavourable for protein synthesis are determined. By residual fixation one should mean accumulation of strA mutations stable to antimutagenous effect of photoreactivating light in cell population incubated in buffer after UV radiation. It is established that residual fixation is small in cultures, conforming to deep decrease, and is a factor (about 40% of strA mutations is fixed) in a culture, conforming to moderate decrease (about 60% of strA mutations disappears) of mutation frequency in incubation under conditions unfavourable for protein synthesis. The conclusion is made that the depth of strA mutation frequency decrease, taking place under the influence of mfd system, depends on the level of residual fixation of this mutations. It is supposed that residual fixation is caused by rpsL (strA) locus introduction in replication cycle initiated after radiation

A Case of Multiple Spontaneous Keloid Scars

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Abdulhadi Jfri

2015-07-01

Full Text Available Keloid scars result from an abnormal healing response to cutaneous injury or inflammation that extends beyond the borders of the original wound. Spontaneous keloid scars forming in the absence of any previous trauma or surgical procedure are rare. Certain syndromes have been associated with this phenomenon, and few reports have discussed the evidence of single spontaneous keloid scar, which raises the question whether they are really spontaneous. Here, we present a 27-year-old mentally retarded single female with orbital hypertelorism, broad nasal bridge, repaired cleft lip and high-arched palate who presented with progressive multiple spontaneous keloid scars in different parts of her body which were confirmed histologically by the presence of typical keloidal collagen. This report supports the fact that keloid scars can appear spontaneously and are possibly linked to a genetic factor. Furthermore, it describes a new presentation of spontaneous keloid scars in the form of multiple large lesions in different sites of the body.

CD48-deficient T-lymphocytes from DMBA-treated rats have de novo mutations in the endogenous Pig-a gene.

Science.gov (United States)

Dobrovolsky, Vasily N; Revollo, Javier; Pearce, Mason G; Pacheco-Martinez, M Monserrat; Lin, Haixia

2015-10-01

A major question concerning the scientific and regulatory acceptance of the rodent red blood cell-based Pig-a gene mutation assay is the extent to which mutants identified by their phenotype in the assay are caused by mutations in the Pig-a gene. In this study, we identified T-lymphocytes deficient for the glycosylphosphatidylinositol-anchored surface marker, CD48, in control and 7,12-dimethylbenz[a]anthracene (DMBA)-treated rats using a flow cytometric assay and determined the spectra of mutations in the endogenous Pig-a gene in these cells. CD48-deficient T-cells were seeded by sorting at one cell per well into 96-well plates, expanded into clones, and exons of their genomic Pig-a were sequenced. The majority (78%) of CD48-deficient T-cell clones from DMBA-treated rats had mutations in the Pig-a gene. The spectrum of DMBA-induced Pig-a mutations was dominated by mutations at A:T, with the mutated A being on the nontranscribed strand and A → T transversion being the most frequent change. The spectrum of Pig-a mutations in DMBA-treated rats was different from the spectrum of Pig-a mutations in N-ethyl-N-nitrosourea (ENU)-treated rats, but similar to the spectrum of DMBA mutations for another endogenous X-linked gene, Hprt. Only 15% of CD48-deficient mutants from control animals contained Pig-a mutations; T-cell biology may be responsible for a relatively large fraction of false Pig-a mutant lymphocytes in control animals. Among the verified mutants from control rats, the most common were frameshifts and deletions. The differences in the spectra of spontaneous, DMBA-, and ENU-induced Pig-a mutations suggest that the flow cytometric Pig-a assay detects de novo mutation in the endogenous Pig-a gene. © 2015 Wiley Periodicals, Inc.

The somatic FAH C.1061C>A change counteracts the frequent FAH c.1062+5G>A mutation and permits U1snRNA-based splicing correction

NARCIS (Netherlands)

Scalet, Daniela; Sacchetto, Claudia; Bernardi, Francesco; Pinotti, Mirko; van de Graaf, Stan F. J.; Balestra, Dario

2018-01-01

In tyrosinaemia type 1(HT1), a mosaic pattern of fumarylacetoacetase (FAH) immunopositive or immunonegative nodules in liver tissue has been reported in many patients. This aspect is generally explained by a spontaneous reversion of the mutation into a normal genotype. In one HT1 patient carrying

Oxidative Stress in Dilated Cardiomyopathy Caused by MYBPC3 Mutation

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Thomas L. Lynch

2015-01-01

Full Text Available Cardiomyopathies can result from mutations in genes encoding sarcomere proteins including MYBPC3, which encodes cardiac myosin binding protein-C (cMyBP-C. However, whether oxidative stress is augmented due to contractile dysfunction and cardiomyocyte damage in MYBPC3-mutated cardiomyopathies has not been elucidated. To determine whether oxidative stress markers were elevated in MYBPC3-mutated cardiomyopathies, a previously characterized 3-month-old mouse model of dilated cardiomyopathy (DCM expressing a homozygous MYBPC3 mutation (cMyBP-C(t/t was used, compared to wild-type (WT mice. Echocardiography confirmed decreased percentage of fractional shortening in DCM versus WT hearts. Histopathological analysis indicated a significant increase in myocardial disarray and fibrosis while the second harmonic generation imaging revealed disorganized sarcomeric structure and myocyte damage in DCM hearts when compared to WT hearts. Intriguingly, DCM mouse heart homogenates had decreased glutathione (GSH/GSSG ratio and increased protein carbonyl and lipid malondialdehyde content compared to WT heart homogenates, consistent with elevated oxidative stress. Importantly, a similar result was observed in human cardiomyopathy heart homogenate samples. These results were further supported by reduced signals for mitochondrial semiquinone radicals and Fe-S clusters in DCM mouse hearts measured using electron paramagnetic resonance spectroscopy. In conclusion, we demonstrate elevated oxidative stress in MYPBC3-mutated DCM mice, which may exacerbate the development of heart failure.

Spontaneous ignition characteristics of coal in a large-scale furnace: An experimental and numerical investigation

International Nuclear Information System (INIS)

Wen, Hu; Yu, Zhijin; Deng, Jun; Zhai, Xiaowei

2017-01-01

Highlights: • Three coal spontaneous combustion coupled models based on various flow equations were constructed and compared. • The airflow behavior in loose coal should be defined as a Brinkman flow. • The self-heating of coal in a large-scale reactor was numerically reappeared. • The effect of heat dissipated conditions on temperature profiles of broken coal was presented. - Abstract: A comprehensive understanding of the spontaneous combustion characteristics of coal in various surroundings is necessary for developing reliable test platform and predictive models. In this study, the characteristics of oxidation and self-heating combining various gas flow equations in loose coal were investigated separately and used to simulate the experimental procedure of spontaneous combustion. The main focus was to investigate the effect of thermal boundary on temperature profiles as well as spontaneous combustion period. The results showed that the numerical approach was validated by comparison with the test data. Furthermore, the model based upon Brinkman equation showed a higher accuracy, which indicated that airflow behavior influences the balances of coal oxidation and heat dissipation, thus impacts the temperature profiles of loose coal. The areas of high temperature zones would be evidently expanded and the spontaneous ignition time would be significantly accelerated if the thermal exchange between the coal and its surroundings decreased. Our results, especially for the field of engineering, have substantial effects for grasping and controlling coal spontaneous combustion disaster.

Matrilin-3 chondrodysplasia mutations cause attenuated chondrogenesis, premature hypertrophy and aberrant response to TGF-β in chondroprogenitor cells.

Science.gov (United States)

Jayasuriya, Chathuraka T; Zhou, Fiona H; Pei, Ming; Wang, Zhengke; Lemme, Nicholas J; Haines, Paul; Chen, Qian

2014-08-21

Studies have shown that mutations in the matrilin-3 gene (MATN3) are associated with multiple epiphyseal dysplasia (MED) and spondyloepimetaphyseal dysplasia (SEMD). We tested whether MATN3 mutations affect the differentiation of chondroprogenitor and/or mesenchymal stem cells, which are precursors to chondrocytes. ATDC5 chondroprogenitors stably expressing wild-type (WT) MATN3 underwent spontaneous chondrogenesis. Expression of chondrogenic markers collagen II and aggrecan was inhibited in chondroprogenitors carrying the MED or SEMD MATN3 mutations. Hypertrophic marker collagen X remained attenuated in WT MATN3 chondroprogenitors, whereas its expression was elevated in chondroprogenitors expressing the MED or SEMD mutant MATN3 gene suggesting that these mutations inhibit chondrogenesis but promote hypertrophy. TGF-β treatment failed to rescue chondrogenesis markers but dramatically increased collagen X mRNA expression in mutant MATN3 expressing chondroprogenitors. Synovium derived mesenchymal stem cells harboring the SEMD mutation exhibited lower glycosaminoglycan content than those of WT MATN3 in response to TGF-β. Our results suggest that the properties of progenitor cells harboring MATN3 chondrodysplasia mutations were altered, as evidenced by attenuated chondrogenesis and premature hypertrophy. TGF-β treatment failed to completely rescue chondrogenesis but instead induced hypertrophy in mutant MATN3 chondroprogenitors. Our data suggest that chondroprogenitor cells should be considered as a potential target of chondrodysplasia therapy.

Matrilin-3 Chondrodysplasia Mutations Cause Attenuated Chondrogenesis, Premature Hypertrophy and Aberrant Response to TGF-β in Chondroprogenitor Cells

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Chathuraka T. Jayasuriya

2014-08-01

Full Text Available Studies have shown that mutations in the matrilin-3 gene (MATN3 are associated with multiple epiphyseal dysplasia (MED and spondyloepimetaphyseal dysplasia (SEMD. We tested whether MATN3 mutations affect the differentiation of chondroprogenitor and/or mesenchymal stem cells, which are precursors to chondrocytes. ATDC5 chondroprogenitors stably expressing wild-type (WT MATN3 underwent spontaneous chondrogenesis. Expression of chondrogenic markers collagen II and aggrecan was inhibited in chondroprogenitors carrying the MED or SEMD MATN3 mutations. Hypertrophic marker collagen X remained attenuated in WT MATN3 chondroprogenitors, whereas its expression was elevated in chondroprogenitors expressing the MED or SEMD mutant MATN3 gene suggesting that these mutations inhibit chondrogenesis but promote hypertrophy. TGF-β treatment failed to rescue chondrogenesis markers but dramatically increased collagen X mRNA expression in mutant MATN3 expressing chondroprogenitors. Synovium derived mesenchymal stem cells harboring the SEMD mutation exhibited lower glycosaminoglycan content than those of WT MATN3 in response to TGF-β. Our results suggest that the properties of progenitor cells harboring MATN3 chondrodysplasia mutations were altered, as evidenced by attenuated chondrogenesis and premature hypertrophy. TGF-β treatment failed to completely rescue chondrogenesis but instead induced hypertrophy in mutant MATN3 chondroprogenitors. Our data suggest that chondroprogenitor cells should be considered as a potential target of chondrodysplasia therapy.

High mutation rates limit evolutionary adaptation in Escherichia coli.

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Kathleen Sprouffske

2018-04-01

Full Text Available Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli's genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild.

High mutation rates limit evolutionary adaptation in Escherichia coli

Science.gov (United States)

Wagner, Andreas

2018-01-01

Mutation is fundamental to evolution, because it generates the genetic variation on which selection can act. In nature, genetic changes often increase the mutation rate in systems that range from viruses and bacteria to human tumors. Such an increase promotes the accumulation of frequent deleterious or neutral alleles, but it can also increase the chances that a population acquires rare beneficial alleles. Here, we study how up to 100-fold increases in Escherichia coli’s genomic mutation rate affect adaptive evolution. To do so, we evolved multiple replicate populations of asexual E. coli strains engineered to have four different mutation rates for 3000 generations in the laboratory. We measured the ability of evolved populations to grow in their original environment and in more than 90 novel chemical environments. In addition, we subjected the populations to whole genome population sequencing. Although populations with higher mutation rates accumulated greater genetic diversity, this diversity conveyed benefits only for modestly increased mutation rates, where populations adapted faster and also thrived better than their ancestors in some novel environments. In contrast, some populations at the highest mutation rates showed reduced adaptation during evolution, and failed to thrive in all of the 90 alternative environments. In addition, they experienced a dramatic decrease in mutation rate. Our work demonstrates that the mutation rate changes the global balance between deleterious and beneficial mutational effects on fitness. In contrast to most theoretical models, our experiments suggest that this tipping point already occurs at the modest mutation rates that are found in the wild. PMID:29702649

Inhibition of mutant IDH1 decreases D-2-HG levels without affecting tumorigenic properties of chondrosarcoma cell lines.

Science.gov (United States)

Suijker, Johnny; Oosting, Jan; Koornneef, Annemarie; Struys, Eduard A; Salomons, Gajja S; Schaap, Frank G; Waaijer, Cathelijn J F; Wijers-Koster, Pauline M; Briaire-de Bruijn, Inge H; Haazen, Lizette; Riester, Scott M; Dudakovic, Amel; Danen, Erik; Cleton-Jansen, Anne-Marie; van Wijnen, Andre J; Bovée, Judith V M G

2015-05-20

Mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 are found in a subset of benign and malignant cartilage tumors, gliomas and leukaemias. The mutant enzyme causes the production of D-2-hydroxyglutarate (D-2-HG), affecting CpG island and histone methylation. While mutations in IDH1/2 are early events in benign cartilage tumors, we evaluated whether these mutations play a role in malignant chondrosarcomas. Compared to IDH1/2 wildtype cell lines, chondrosarcoma cell lines harboring an endogenous IDH1 (n=3) or IDH2 mutation (n=2) showed up to a 100-fold increase in intracellular and extracellular D-2-HG levels. Specific inhibition of mutant IDH1 using AGI-5198 decreased levels of D-2-HG in a dose dependent manner. After 72 hours of treatment one out of three mutant IDH1 cell lines showed a moderate decrease in viability , while D-2-HG levels decreased >90%. Likewise, prolonged treatment (up to 20 passages) did not affect proliferation and migration. Furthermore, global gene expression, CpG island methylation as well as histone H3K4, -9, and -27 trimethylation levels remained unchanged. Thus, while IDH1/2 mutations cause enchondroma, malignant progression towards central chondrosarcoma renders chondrosarcoma growth independent of these mutations. Thus, monotherapy based on inhibition of mutant IDH1 appears insufficient for treatment of inoperable or metastasized chondrosarcoma patients.

Mutation induction in γ-irradiated primary human bronchial epithelial cells and molecular analysis of the HPRT- mutants

International Nuclear Information System (INIS)

Suzuki, Keiji; Hei, Tom K.

1996-01-01

We have examined various radiobiological parameters using commercially-available primary normal human bronchial epithelial (NHBE) cells, which can be subcultured more than 20 population doublings, and have established the mutation system in order to characterize the molecular changes in γ-irradiated primary cells. The survival curve, obtained after irradiation of cells with 137 Cs γ-rays, indicates that the D 0 , D q , and n values are 1.34 Gy, 1.12 Gy, and 2.3, respectively. The induction of HPRT - mutation was dose-dependent and the mutant fraction increased in a non-linear fashion. Since the doubling number of NHBE cells is limited, DNA was extracted directly from the single mutant colonies and alteration in the HPRT gene locus was analyzed using multiplex PCR technique. Among spontaneous mutants, the proportion with total and partial deletions of the gene was 10.0% (2/20) and 60.0% (12/20), respectively, while 30.0% (6/20) did not have any detectable changes in the nine exons examined. On the other hand, the fraction of total deletion increased by more than 2-fold among mutants induced by γ-rays in that 26.3% (10/38) of them showed the total gene deletions. Twenty-five out of 38 γ-induced mutants (65.8%) had partial deletions and 3 mutants (7.9%) had no detectable alteration. The present results showed that γ-irradiation efficiently induced HPRT gene mutation in primary human epithelial cells and that most of the induced mutants suffered larger deletions compared to that observed in spontaneous mutants. This system provides a useful tool for determination of mutagenicity and understanding the molecular mechanisms of environmental carcinogens in primary human bronchial cells

Spontaneous pneumothorax in silicotuberculosis of lung

International Nuclear Information System (INIS)

Kolenic, J.; Jurgova, T.; Zimacek, J.; Vajo, J.; Krchnavy, M.

1995-01-01

The authors describe the case of 62 years old man with the appearance of spontaneous pneumothorax, in whom the basic pulmonary disease was silicotuberculosis of the lung. At clinic of occupational diseases in Kosice have been evidence 965 cases of silicosis and silicotuberculosis. From 1971 they have now the first case of spontaneous pneumothorax. The authors make discussion about possible mechanical and biochemical factors, which cause relatively low incidence of spontaneous pneumothorax in silicosis of the lung. (authors)

Dentate gyrus mossy cells control spontaneous convulsive seizures and spatial memory.

Science.gov (United States)

Bui, Anh D; Nguyen, Theresa M; Limouse, Charles; Kim, Hannah K; Szabo, Gergely G; Felong, Sylwia; Maroso, Mattia; Soltesz, Ivan

2018-02-16

Temporal lobe epilepsy (TLE) is characterized by debilitating, recurring seizures and an increased risk for cognitive deficits. Mossy cells (MCs) are key neurons in the hippocampal excitatory circuit, and the partial loss of MCs is a major hallmark of TLE. We investigated how MCs contribute to spontaneous ictal activity and to spatial contextual memory in a mouse model of TLE with hippocampal sclerosis, using a combination of optogenetic, electrophysiological, and behavioral approaches. In chronically epileptic mice, real-time optogenetic modulation of MCs during spontaneous hippocampal seizures controlled the progression of activity from an electrographic to convulsive seizure. Decreased MC activity is sufficient to impede encoding of spatial context, recapitulating observed cognitive deficits in chronically epileptic mice. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Calculation of the Spontaneous Polarization and the Dielectric Constant as a Function of Temperature for

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Hamit Yurtseven

2012-01-01

Full Text Available The temperature dependence of the spontaneous polarization P is calculated in the ferroelectric phase of KH2PO4 (KDP at atmospheric pressure (TC = 122 K. Also, the dielectric constant ε is calculated at various temperatures in the paraelectric phase of KDP at atmospheric pressure. For this calculation of P and ε, by fitting the observed Raman frequencies of the soft mode, the microscopic parameters of the pure tunnelling model are obtained. In this model, the proton-lattice interaction is not considered and the collective proton mode is identified with the soft-mode response of the system. Our calculations show that the spontaneous polarization decreases continuously in the ferroelectric phase as approaching the transition temperature TC. Also, the dielectric constant decreases with increasing temperature and it diverges in the vicinity of the transition temperature (TC = 122 K for KDP according to the Curie-Weiss law.

Spontaneous body movements in spatial cognition

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Sergiu eTcaci Popescu

2012-05-01

Full Text Available People often perform spontaneous body movements during spatial tasks such as giving complex directions or orienting themselves on maps. How are these spontaneous gestures related to spatial problem-solving? We measured spontaneous movements during a perspective-taking task inspired by map reading. Analyzing the motion data to isolate rotation and translation components of motion in specific geometric relation to the task, we found out that most participants executed spontaneous miniature rotations of the head that were significantly related to the main task parameter. These head rotations were as if participants were trying to align themselves with the orientation on the map either in the image plane or on the ground plane, but with tiny amplitudes, typically below 1% of the actual movements. Our results are consistent with a model of sensorimotor prediction driving spatial reasoning. The efference copy of planned movements triggers this prediction mechanism. The movements themselves may then be mostly inhibited; the small spontaneous gestures that we measure are the visible traces of these planned but inhibited actions.

Spontaneous pneumothorax in diffuse cystic lung diseases.

Science.gov (United States)

Cooley, Joseph; Lee, Yun Chor Gary; Gupta, Nishant

2017-07-01

Diffuse cystic lung diseases (DCLDs) are a heterogeneous group of disorders with varying pathophysiologic mechanisms that are characterized by the presence of air-filled lung cysts. These cysts are prone to rupture, leading to the development of recurrent spontaneous pneumothoraces. In this article, we review the epidemiology, clinical features, and management DCLD-associated spontaneous pneumothorax, with a focus on lymphangioleiomyomatosis, Birt-Hogg-Dubé syndrome, and pulmonary Langerhans cell histiocytosis. DCLDs are responsible for approximately 10% of apparent primary spontaneous pneumothoraces. Computed tomography screening for DCLDs (Birt-Hogg-Dubé syndrome, lymphangioleiomyomatosis, and pulmonary Langerhans cell histiocytosis) following the first spontaneous pneumothorax has recently been shown to be cost-effective and can help facilitate early diagnosis of the underlying disorders. Patients with DCLD-associated spontaneous pneumothorax have a very high rate of recurrence, and thus pleurodesis should be considered following the first episode of spontaneous pneumothorax in these patients, rather than waiting for a recurrent episode. Prior pleurodesis is not a contraindication to future lung transplant. Although DCLDs are uncommon, spontaneous pneumothorax is often the sentinel event that provides an opportunity for diagnosis. By understanding the burden and implications of pneumothoraces in DCLDs, clinicians can facilitate early diagnosis and appropriate management of the underlying disorders.

Relatively high rates of G:C → A:T transitions at CpG sites were observed in certain epithelial tissues including pancreas and submaxillary gland of adult big blue® mice.

Science.gov (United States)

Prtenjaca, Anita; Tarnowski, Heather E; Marr, Alison M; Heney, Melanie A; Creamer, Laura; Sathiamoorthy, Sarmitha; Hill, Kathleen A

2014-01-01

With few exceptions, spontaneous mutation frequency and pattern are similar across tissue types and relatively constant in young to middle adulthood in wild type mice. Underrepresented in surveys of spontaneous mutations across murine tissues is the diversity of epithelial tissues. For the first time, spontaneous mutations were detected in pancreas and submaxillary gland and compared with kidney, lung, and male germ cells from five adult male Big Blue® mice. Mutation load was assessed quantitatively through measurement of mutant and mutation frequency and qualitatively through identification of mutations and characterization of recurrent mutations, multiple mutations, mutation pattern, and mutation spectrum. A total of 9.6 million plaque forming units were screened, 226 mutants were collected, and 196 independent mutations were identified. Four novel mutations were discovered. Spontaneous mutation frequency was low in pancreas and high in the submaxillary gland. The submaxillary gland had multiple recurrent mutations in each of the mice and one mutant had two independent mutations. Mutation patterns for epithelial tissues differed from that observed in male germ cells with a striking bias for G:C to A:T transitions at CpG sites. A comprehensive review of lacI spontaneous mutation patterns in young adult mice and rats identified additional examples of this mutational bias. An overarching observation about spontaneous mutation frequency in adult tissues of the mouse remains one of stability. A repeated observation in certain epithelial tissues is a higher rate of G:C to A:T transitions at CpG sites and the underlying mechanisms for this bias are not known. Copyright © 2013 Wiley Periodicals, Inc.

FEL gain optimisation and spontaneous radiation

Energy Technology Data Exchange (ETDEWEB)

Bali, L.M.; Srivastava, A.; Pandya, T.P. [Lucknow Univ. (India)] [and others

1995-12-31

Colson have evaluated FEL gains for small deviations from perfect electron beam injection, with radiation of the same polarisation as that of the wiggler fields. We find that for optimum gain the polarisation of the optical field should be the same as that of the spontaneous emission under these conditions. With a helical wiggler the axial oscillations resulting from small departures from perfect electron beam injection lead to injection dependent unequal amplitudes and phases of the spontaneous radiation in the two transverse directions. Viewed along the axis therefore the spontaneous emission is elliptically polarised. The azimuth of the ellipse varies with the difference of phase of the two transverse components of spontaneous emission but the eccentricity remains the same. With planar wigglers the spontaneous emission viewed in the axial direction is linearly polarised, again with an injection dependent azimuth. For optimum coherent gain of a radiation field its polarisation characteristics must be the same as those of the spontaneous radiation with both types of wiggler. Thus, with a helical wiggler and the data reported earlier, an increase of 10% in the FEL gain at the fundamental frequency and of 11% at the fifth harmonic has been calculated in the small gain per pass limit. Larger enhancements in gain may result from more favourable values of input parameters.

Spontaneous Bacterial Peritonitis in Subclinical Hypothyroidism

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Dalip Gupta

2013-11-01

Full Text Available Hypothyroidism is an uncommon cause of ascites. Here we describe a case of a 75 year-old female patient with spontaneous bacterial peritonitis and subclinical hypothyroidism that resolved with thyroid replacement and antibiotic therapy respectively. Ascitic fluid analysis revealed a gram-positive bacterium on gram staining. A review of the literature revealed just one other reported case of myxoedema ascites with concomitant spontaneous bacterial peritonitis and no case has till been reported of spontaneous bacterial peritonitis in subclinical hypothyroidism.

Intracerebroventricular metformin attenuates salt-induced hypertension in spontaneously hypertensive rats

DEFF Research Database (Denmark)

Petersen, J S; Andersen, D; Muntzel, M S

2001-01-01

The aim of this study was to examine the effects of long-term continuous intracerebroventricular (icv) infusion of metformin on blood pressure (BP) in spontaneously hypertensive rats (SHR). To accelerate the development of hypertension, SHR were fed a 8% NaCl diet during the 3-week study period...... to hexamethonium was attenuated by all doses of metformin suggesting that chronic icv metformin decreased central sympathetic outflow. The highest doses of metformin (100 and 200 microg/day) also prevented development of hypertension, but these doses were highly neurotoxic as demonstrated by histologic evaluation...... doses of metformin attenuates hypertension and decreases the hypotensive responses to ganglionic blockade in SHR, suggesting a centrally elicited sympathoinhibitory action....

Cavity-enhanced spontaneous emission rates for rhodamine 6-G in levitated microdroplets

International Nuclear Information System (INIS)

Barnes, M.D.; Whitten, W.B.; Ramsey, J.M.; Arnold, S.

1992-01-01

Fluorescence decay kinetics of Rhodamine 6-G molecules in levitated glycerol microdroplets (4--20 microns in diameter) have been investigated to determine the effects of spherical cavity resonances on spontaneous emission rates. For droplet diameters greater than 10 microns, the fluorescence lifetime is essentially the same as in bulk glycerol. As the droplet diameter is decreased below 10 microns, bi-exponential decay behavior is observed with a slow component whose rate is similar to bulk glycerol, and a fast component whose rate is as much as a factor of 10 larger than the bulk decay rate. This fast component is attributed to cavity enhancement of the spontaneous emission rate and, within the weak coupling approximation, a value for the homogeneous linewidth at room temperature can be estimated from the fluorescence lifetime data

Spontaneous shaker rat mutant - a new model for X-linked tremor/ataxia.

Science.gov (United States)

Figueroa, Karla P; Paul, Sharan; Calì, Tito; Lopreiato, Raffaele; Karan, Sukanya; Frizzarin, Martina; Ames, Darren; Zanni, Ginevra; Brini, Marisa; Dansithong, Warunee; Milash, Brett; Scoles, Daniel R; Carafoli, Ernesto; Pulst, Stefan M

2016-05-01

The shaker rat is an X-linked recessive spontaneous model of progressive Purkinje cell (PC) degeneration exhibiting a shaking ataxia and wide stance. Generation of Wistar Furth (WF)/Brown Norwegian (BN) F1 hybrids and genetic mapping of F2 sib-sib offspring using polymorphic markers narrowed the candidate gene region to 26 Mbp denoted by the last recombinant genetic marker DXRat21 at 133 Mbp to qter (the end of the long arm). In the WF background, the shaker mutation has complete penetrance, results in a stereotypic phenotype and there is a narrow window for age of disease onset; by contrast, the F2 hybrid phenotype was more varied, with a later age of onset and likely non-penetrance of the mutation. By deep RNA-sequencing, five variants were found in the candidate region; four were novel without known annotation. One of the variants caused an arginine (R) to cysteine (C) change at codon 35 of the ATPase, Ca(2+) transporting, plasma membrane 3 (Atp2b3) gene encoding PMCA3 that has high expression in the cerebellum. The variant was well supported by hundreds of overlapping reads, and was found in 100% of all affected replicas and 0% of the wild-type (WT) replicas. The mutation segregated with disease in all affected animals and the amino acid change was found in an evolutionarily conserved region of PMCA3. Despite strong genetic evidence for pathogenicity, in vitro analyses of PMCA3(R35C) function did not show any differences to WT PMCA3. Because Atp2b3 mutation leads to congenital ataxia in humans, the identified Atp2b3 missense change in the shaker rat presents a good candidate for the shaker rat phenotype based on genetic criteria, but cannot yet be considered a definite pathogenic variant owing to lack of functional changes. © 2016. Published by The Company of Biologists Ltd.

Spontaneous regression of intracranial malignant lymphoma. Case report

Energy Technology Data Exchange (ETDEWEB)

Kojo, Nobuto; Tokutomi, Takashi; Eguchi, Gihachirou; Takagi, Shigeyuki; Matsumoto, Tomie; Sasaguri, Yasuyuki; Shigemori, Minoru.

1988-05-01

In a 46-year-old female with a 1-month history of gait and speech disturbances, computed tomography (CT) demonstrated mass lesions of slightly high density in the left basal ganglia and left frontal lobe. The lesions were markedly enhanced by contrast medium. The patient received no specific treatment, but her clinical manifestations gradually abated and the lesions decreased in size. Five months after her initial examination, the lesions were absent on CT scans; only a small area of low density remained. Residual clinical symptoms included mild right hemiparesis and aphasia. After 14 months the patient again deteriorated, and a CT scan revealed mass lesions in the right frontal lobe and the pons. However, no enhancement was observed in the previously affected regions. A biopsy revealed malignant lymphoma. Despite treatment with steroids and radiation, the patient's clinical status progressively worsened and she died 27 months after initial presentation. Seven other cases of spontaneous regression of primary malignant lymphoma have been reported. In this case, the mechanism of the spontaneous regression was not clear, but changes in immunologic status may have been involved.

Spontaneous De-Icing Phenomena on Extremely Cold Surfaces

Science.gov (United States)

Song, Dong; Choi, Chang-Hwan

2017-11-01

Freezing of droplets on cold surfaces is universal phenomenon, while the mechanisms are still inadequately understood. Here we report spontaneous de-icing phenomena of an impacting droplet which occur on extreme cold surfaces. When a droplet impacts on cold surfaces lower than -80°, it takes more than two times longer for the droplet to freeze than the ones at -50°. Moreover, the frozen droplet below -80° breaks up into several large parts spontaneously in the end. When a droplet impacts on the extreme cold surfaces, evaporation and condensation occur immediately as the droplet approaches the substrate. A thick layer of frost forms between the droplet and substrate, decreasing the contact area of the droplet with substrate. It leads to impede the heat transfer and hence extends the freezing time significantly. On the extremely cold substrate, the droplet freezes from the center to the edge area, in contrast to a typical case freezing from the bottom to the top. This novel from-center-to-edge freezing process changes the internal tension of the frozen droplet and results in the instantaneous breakup and release eventually, which can be taken advantage of for effective deicing mechanisms.

Visually Evoked Spiking Evolves While Spontaneous Ongoing Dynamics Persist

Science.gov (United States)

Huys, Raoul; Jirsa, Viktor K.; Darokhan, Ziauddin; Valentiniene, Sonata; Roland, Per E.

2016-01-01

Neurons in the primary visual cortex spontaneously spike even when there are no visual stimuli. It is unknown whether the spiking evoked by visual stimuli is just a modification of the spontaneous ongoing cortical spiking dynamics or whether the spontaneous spiking state disappears and is replaced by evoked spiking. This study of laminar recordings of spontaneous spiking and visually evoked spiking of neurons in the ferret primary visual cortex shows that the spiking dynamics does not change: the spontaneous spiking as well as evoked spiking is controlled by a stable and persisting fixed point attractor. Its existence guarantees that evoked spiking return to the spontaneous state. However, the spontaneous ongoing spiking state and the visual evoked spiking states are qualitatively different and are separated by a threshold (separatrix). The functional advantage of this organization is that it avoids the need for a system reorganization following visual stimulation, and impedes the transition of spontaneous spiking to evoked spiking and the propagation of spontaneous spiking from layer 4 to layers 2–3. PMID:26778982

Calorie restriction reduces the incidence of radiation-induced myeloid leukemia and spontaneous tumor

International Nuclear Information System (INIS)

Yoshida, Kazuko

1999-01-01

The host-defense mechanisms against cancers are known to be modulated by changing the environmental factor(s). The spontaneous incidence of myeloid leukemia is about 1% in C3H/He mice, and the incidence increases up to 23.3% when a single dose of radiation, 3 Gy X-ray, is exposed to a whole-body. Since calorie restriction was known to reduce the incidence of spontaneous tumors, a question as to whether such radiation induced-increase of myeloid leukemia would be also decreased by calorie restriction, was aimed to answer to elucidate possible mechanism of radiation-induced myeloid leukemia. By the calorie restriction, the incidence of myeloid leukemia was significantly decreased; it was reduced to 7.9% and 10.7% when restriction was started before (6 weeks old) and after (10 weeks old) irradiation, respectively. In addition, the latent period of the myeloid leukemia in the groups for calorie restriction was significantly extended at a greater extent as compared with the control diet groups. Number of hematopoietic stem cells, the possible target cells for radiation-induced leukemias, in the groups for the calorie restriction demonstrated a significant decrease, especially in the spleen, as compared with that in the control, when the evaluation was made at the time of radiation exposure. Then, we examined whether the decreased number of target cells at the time of exposure is caused by the reduction of radiation-induced myeloid leukemia with caloric restriction. The third restricted groups were fed 65 kcal diet (restricted diet) for the first 4 weeks i.e. from 6 weeks to 10 weeks old, then, the mice were fed with control diet after radiation. The incidence of myeloid leukemia in this group was slightly decreased but did not show statistically significance. Therefore, the caloric restriction seems to be more effective in the promotion stage than the initiation stage on radiation-induced leukemogenesis. It is well known that C3H/He mice develop hepatoma spontaneously

Peritonitis - spontaneous bacterial

Science.gov (United States)

Spontaneous bacterial peritonitis (SBP); Ascites - peritonitis; Cirrhosis - peritonitis ... who are on peritoneal dialysis for kidney failure. Peritonitis may have other causes . These include infection from ...

Spontaneous insertion of GPI anchors into cholesterol-rich membrane domains

Directory of Open Access Journals (Sweden)

Jing Li

2018-05-01

Full Text Available GPI-Anchored proteins (GPI-APs can be exogenously transferred onto bilayer membranes both in vivo and in vitro, while the mechanism by which this transfer process occurs is unknown. In this work, we used atomistic molecular dynamics simulations and free energy calculations to characterize the essential influence of cholesterol on insertion of the GPI anchors into plasma membranes. We demonstrate, both dynamically and energetically, that in the presence of cholesterol, the tails of GPI anchors are able to penetrate inside the core of the lipid membrane spontaneously with a three-step mechanism, while in the absence of cholesterol no spontaneous insertion was observed. We ascribe the failure of insertion to the strong thermal fluctuation of lipid molecules in cholesterol-free bilayer, which generates a repulsive force in entropic origin. In the presence of cholesterol, however, the fluctuation of lipids is strongly reduced, thus decreasing the barrier for the anchor insertion. Based on this observation, we propose a hypothesis that addition of cholesterol creates vertical creases in membranes for the insertion of acyl chains. Moreover, we find that the GPI anchor could also spontaneously inserted into the boundary between cholesterol-rich and cholesterol-depleted domains. Our results shed light on the mechanism of cholesterol-mediated interaction between membrane proteins with acyl chain and plasma membranes in living cells.

Spontaneous insertion of GPI anchors into cholesterol-rich membrane domains

Science.gov (United States)

Li, Jing; Liu, Xiuhua; Tian, Falin; Yue, Tongtao; Zhang, Xianren; Cao, Dapeng

2018-05-01

GPI-Anchored proteins (GPI-APs) can be exogenously transferred onto bilayer membranes both in vivo and in vitro, while the mechanism by which this transfer process occurs is unknown. In this work, we used atomistic molecular dynamics simulations and free energy calculations to characterize the essential influence of cholesterol on insertion of the GPI anchors into plasma membranes. We demonstrate, both dynamically and energetically, that in the presence of cholesterol, the tails of GPI anchors are able to penetrate inside the core of the lipid membrane spontaneously with a three-step mechanism, while in the absence of cholesterol no spontaneous insertion was observed. We ascribe the failure of insertion to the strong thermal fluctuation of lipid molecules in cholesterol-free bilayer, which generates a repulsive force in entropic origin. In the presence of cholesterol, however, the fluctuation of lipids is strongly reduced, thus decreasing the barrier for the anchor insertion. Based on this observation, we propose a hypothesis that addition of cholesterol creates vertical creases in membranes for the insertion of acyl chains. Moreover, we find that the GPI anchor could also spontaneously inserted into the boundary between cholesterol-rich and cholesterol-depleted domains. Our results shed light on the mechanism of cholesterol-mediated interaction between membrane proteins with acyl chain and plasma membranes in living cells.

Search for spontaneous fission of 226Ra and systematics of the spontaneous fission, α-decay and cluster decay probabilities

International Nuclear Information System (INIS)

Mikheev, V.L.; Tret'yakova, S.P.; Golovchenko, A.N.; Timofeeva, O.V.; Hussonnois, M.; Le Naour, C.

1998-01-01

The low limit of the 226 Ra spontaneous fission half-life corresponding to T 1/2 ≥ 4 · 10 18 years is measured. The 226 Ra spontaneous fission probability proved to be about 50 times less than the value expected from the known systematics, connecting the ratios of theα-decay and spontaneous fission probabilities with the fissility parameter Z 2 /A. It is shown that the probabilities of spontaneous fission, α-decay and cluster decay can be systematized in the same way according to the difference between the decay products Coulomb energy near the scission point and decay energy Q

Dorsomedial prefontal cortex supports spontaneous thinking per se.

Science.gov (United States)

Raij, T T; Riekki, T J J

2017-06-01

Spontaneous thinking, an action to produce, consider, integrate, and reason through mental representations, is central to our daily experience and has been suggested to serve crucial adaptive purposes. Such thinking occurs among other experiences during mind wandering that is associated with activation of the default mode network among other brain circuitries. Whether and how such brain activation is linked to the experience of spontaneous thinking per se remains poorly known. We studied 51 healthy subjects using a comprehensive experience-sampling paradigm during 3T functional magnetic resonance imaging. In comparison with fixation, the experiences of spontaneous thinking and spontaneous perception were related to activation of wide-spread brain circuitries, including the cortical midline structures, the anterior cingulate cortex and the visual cortex. In direct comparison of the spontaneous thinking versus spontaneous perception, activation was observed in the anterior dorsomedial prefrontal cortex. Modality congruence of spontaneous-experience-related brain activation was suggested by several findings, including association of the lingual gyrus with visual in comparison with non-verbal-non-visual thinking. In the context of current literature, these findings suggest that the cortical midline structures are involved in the integrative core substrate of spontaneous thinking that is coupled with other brain systems depending on the characteristics of thinking. Furthermore, involvement of the anterior dorsomedial prefrontal cortex suggests the control of high-order abstract functions to characterize spontaneous thinking per se. Hum Brain Mapp 38:3277-3288, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A novel Dock8 gene mutation confers diabetogenic susceptibility in the LEW.1AR1/Ztm-iddm rat, an animal model of human type 1 diabetes

NARCIS (Netherlands)

Arndt, Tanja; Wedekind, Dirk; Jörns, Anne; Tsiavaliaris, Georgios; Cuppen, Edwin; Hedrich, Hans-Jürgen; Lenzen, Sigurd

2015-01-01

AIMS/HYPOTHESIS: The LEW.1AR1-iddm rat, an animal model of human type 1 diabetes, arose through a spontaneous mutation within the inbred strain LEW.1AR1. A susceptibility locus (Iddm8) on rat chromosome 1 (RNO1) has been identified previously, which is accompanied by autoimmune diabetes and the

Maternal smoking predicts the risk of spontaneous abortion

DEFF Research Database (Denmark)

Nielsen, Ann; Hannibal, Charlotte Gerd; Lindekilde, Bodil Eriksen

2006-01-01

BACKGROUND: Few studies have examined smoking prior to pregnancy and the occurrence of spontaneous abortion, as most studies have addressed the risk of spontaneous abortion in relation to smoking during pregnancy. However, results are not entirely consistent. The aim of the present study...... was to assess the risk of spontaneous abortion considering smoking prior to pregnancy. METHODS: We performed a nested case-control study using prospective data from a population-based cohort comprising 11,088 women aged 20-29 years. From this cohort, women who experienced either a spontaneous abortion (n=343......) or who gave birth (n=1,578) during follow-up were selected. Associations between self-reported smoking at enrollment and subsequent spontaneous abortion were analyzed by means of multiple logistic regression. RESULTS: The risk of spontaneous abortion in relation to pre-pregnancy smoking showed a clear...

Abrupt onset of mutations in a developmentally regulated gene during terminal differentiation of post-mitotic photoreceptor neurons in mice.

Directory of Open Access Journals (Sweden)

Ivette M Sandoval

Full Text Available For sensitive detection of rare gene repair events in terminally differentiated photoreceptors, we generated a knockin mouse model by replacing one mouse rhodopsin allele with a form of the human rhodopsin gene that causes a severe, early-onset form of retinitis pigmentosa. The human gene contains a premature stop codon at position 344 (Q344X, cDNA encoding the enhanced green fluorescent protein (EGFP at its 3' end, and a modified 5' untranslated region to reduce translation rate so that the mutant protein does not induce retinal degeneration. Mutations that eliminate the stop codon express a human rhodopsin-EGFP fusion protein (hRho-GFP, which can be readily detected by fluorescence microscopy. Spontaneous mutations were observed at a frequency of about one per retina; in every case, they gave rise to single fluorescent rod cells, indicating that each mutation occurred during or after the last mitotic division. Additionally, the number of fluorescent rods did not increase with age, suggesting that the rhodopsin gene in mature rod cells is less sensitive to mutation than it is in developing rods. Thus, there is a brief developmental window, coinciding with the transcriptional activation of the rhodopsin locus, in which somatic mutations of the rhodopsin gene abruptly begin to appear.

Retrospective genetic study of germinative mutations in Str loci of individuals potentially exposed to ionizing radiation;Estudo genetico retrospectivo de mutacoes germinativas em Loci Str de individuos potencialmente expostos a radiacao ionizante

Energy Technology Data Exchange (ETDEWEB)

Costa, Emilia Oliveira Alves

2010-07-01

The Brazilian radiological accident that occurred in 1987, in Goiania, it was a terrible radiation episode. As a consequence, hundreds of people were contaminated due to the Cesium-137 radiation. Recently, many studies had shown that genome instabilities, such as, mutations, chromosomal aberrations, micronuclei formation and micro satellite instability and a delay on cellular death are usually reported on mammal cells exposed to ionizing radiation, being considered as a manly risk to humans. Mutations can be spontaneous, and the occurrence is dependent on the organism, or, induced, being associated to mutagenic exposition. Ionizing radiations are an example of physical and mutagenic agents that could harm the cell repair and could cause the development of many types of cancer. The evaluation of the biological effects of the ionizing radiation, in somatic and germ line cells, with a consequent determination of the radio-induced mutations, it is extremely important to estimate the genetic risks, manly in population exposed to radiation. The analyses of repetitive DNA sequences have been demonstrated that such sequences are prone to high rates of spontaneous mutations. The minisatellites and microsatellites have been used to demonstrate the induction of germ line mutation rates on mouse, humans, among others organisms. The aim of the present study was to analyze the frequency of microsatellite alterations to determine the mutation rates occurred in germ cells of the parents exposed to the ionizing radiation of the Cesium-137. The studied group was constitute of 10 families of individuals accidentally exposed to Cesium-137 and by the control group constituted by 645 healthy individuals who carried out paternity tests on 2009. We found only one mutation of paternal origin in the D8S1179 locus on the exposed group, being the mutation rate of 0.002. In the control group, we found 01 mutation on D16S539 loei and on D3S1358; 02 mutations on Penta E loeus; 04 mutations on D

Osteonecrosis or spontaneous fractures following renal transplantation

International Nuclear Information System (INIS)

Andresen, J.; Nielsen, H.E.; Aarhus Univ.

1981-01-01

31 renal transplant recipients with posttransplant development of osteonecrosis or spontaneous fractures were evaluated with regard to age, duration of dialysis before transplantation. Determination of metacarpal bone mass at the time of transplantation and registration of bone resorption and soft tissue calcification at the time of transplantation and at the time of onset of osteonecrosis and spontaneous fractures were made. Apart from the increased mean age in patients with spontaneous fractures no difference was seen between the groups. Osteonecrosis and spontaneous fractures occurred in areas of trabecular bone. It seems most likely that after renal transplantation the patients show bone complications of different localization. (orig.) [de

Environmental stresses can alleviate the average deleterious effect of mutations

Directory of Open Access Journals (Sweden)

Leibler Stanislas

2003-05-01

Full Text Available Abstract Background Fundamental questions in evolutionary genetics, including the possible advantage of sexual reproduction, depend critically on the effects of deleterious mutations on fitness. Limited existing experimental evidence suggests that, on average, such effects tend to be aggravated under environmental stresses, consistent with the perception that stress diminishes the organism's ability to tolerate deleterious mutations. Here, we ask whether there are also stresses with the opposite influence, under which the organism becomes more tolerant to mutations. Results We developed a technique, based on bioluminescence, which allows accurate automated measurements of bacterial growth rates at very low cell densities. Using this system, we measured growth rates of Escherichia coli mutants under a diverse set of environmental stresses. In contrast to the perception that stress always reduces the organism's ability to tolerate mutations, our measurements identified stresses that do the opposite – that is, despite decreasing wild-type growth, they alleviate, on average, the effect of deleterious mutations. Conclusions Our results show a qualitative difference between various environmental stresses ranging from alleviation to aggravation of the average effect of mutations. We further show how the existence of stresses that are biased towards alleviation of the effects of mutations may imply the existence of average epistatic interactions between mutations. The results thus offer a connection between the two main factors controlling the effects of deleterious mutations: environmental conditions and epistatic interactions.

Human Neuronal Calcium Sensor-1 Protein Avoids Histidine Residues To Decrease pH Sensitivity.

Science.gov (United States)

Gong, Yehong; Zhu, Yuzhen; Zou, Yu; Ma, Buyong; Nussinov, Ruth; Zhang, Qingwen

2017-01-26

pH is highly regulated in mammalian central nervous systems. Neuronal calcium sensor-1 (NCS-1) can interact with numerous target proteins. Compared to that in the NCS-1 protein of Caenorhabditis elegans, evolution has avoided the placement of histidine residues at positions 102 and 83 in the NCS-1 protein of humans and Xenopus laevis, possibly to decrease the conformational sensitivity to pH gradients in synaptic processes. We used all-atom molecular dynamics simulations to investigate the effects of amino acid substitutions between species on human NCS-1 by substituting Arg102 and Ser83 for histidine at neutral (R102H and S83H) and acidic pHs (R102H p and S83H p ). Our cumulative 5 μs simulations revealed that the R102H mutation slightly increases the structural flexibility of loop L2 and the R102H p mutation decreases protein stability. Community network analysis illustrates that the R102H and S83H mutations weaken the interdomain and strengthen the intradomain communications. Secondary structure contents in the S83H and S83H p mutants are similar to those in the wild type, whereas the global structural stabilities and salt-bridge probabilities decrease. This study highlights the conformational dynamics effects of the R102H and S83H mutations on the local structural flexibility and global stability of NCS-1, whereas protonated histidine decreases the stability of NCS-1. Thus, histidines at positions 102 and 83 may not be compatible with the function of NCS-1 whether in the neutral or protonated state.

Cytotoxicity and genotoxicity of UVA irradiation in Chinese hamster ovary cells measured by specific locus mutations, sister chromatid exchanges and chromosome aberrations

International Nuclear Information System (INIS)

Lundgren, Karsten; Wulf, H.C.

1988-01-01

The increasing use of artificial UVA (320-400 nm) suntanning devices has brought attention to possible hazardous effects of UVA. In contrast with earlier studies, several groups recently have described that UVA possibly is mutagenic. We evaluate the genotoxic properties of broad band UVA using CHO cells and three different assays: specific locus (HGPRT) mutations, chromosome aberrations, and sister chromatid exchanges (SCEs). The UVA-source was an UVASUN 2000 S (Mutzhas), emitting UVA above 340 nm. The survival curve of the cells exhibited a shoulder up to 200 kJ/m 2 , that was followed by exponential killing at higher fluences. Mutations were induced linearly in the fluence range of 0-200 kJ/m 2 to a level seven fold higher than the spontaneous, followed by a decrease at fluences above 300 kJ/m 2 . Over the total range of tested fluences (0-300 kJ/m 2 ) a linear dose-response relationship was observed for UVA-induced SCEs. A significantly higher percentage of the cells showed chromosomes with aberrations at the higher levels of exposure (200, 300 and 400 kJ/m 2 ), but no dose response was demonstrated. Our results confirm recent findings showing that UVA is mutagenic in mammalian cells and suggest that UVA exposure may contribute to the total burden of genetic damage caused by exposure to ultraviolet light. (author)

Endosulfan induces changes in spontaneous swimming activity and acetylcholinesterase activity of Jenynsia multidentata (Anablepidae, Cyprinodontiformes)

International Nuclear Information System (INIS)

Ballesteros, M.L.; Durando, P.E.; Nores, M.L.; Diaz, M.P.; Bistoni, M.A.; Wunderlin, D.A.

2009-01-01

We assessed changes in spontaneous swimming activity and acetylcholinesterase (AchE) activity of Jenynsia multidentata exposed to Endosulfan (EDS). Females of J. multidentata were exposed to 0.072 and 1.4 μg L -1 EDS. Average speed and movement percentage were recorded during 48 h. We also exposed females to EDS at five concentrations between 0.072 and 1.4 μg L -1 during 24 h, and measured the AchE activity in brain and muscle. At 0.072 μg L -1 EDS swimming motility decreased relative to the control group after 45 h, while at 1.4 μg L -1 EDS swimming motility decreased after 24 h. AchE activity significantly decreased in muscle when J. multidentata were exposed to EDS above 0.072 μg L -1 , while no significant changes were observed in brain. Thus, changes in swimming activity and AchE activity in muscle are good biomarkers of exposure to EDS in J. multidentata. - This work reports changes observed in spontaneous swimming activity and AchE activity of Jenynsia multidentata exposed to sublethal concentrations of Endosulfan.

Endosulfan induces changes in spontaneous swimming activity and acetylcholinesterase activity of Jenynsia multidentata (Anablepidae, Cyprinodontiformes)

Energy Technology Data Exchange (ETDEWEB)

Ballesteros, M.L. [Facultad de Ciencias Exactas, Fisicas y Naturales, Catedra Diversidad Animal II, Universidad Nacional de Cordoba, Av. Velez Sarsfield 299, 5000 Cordoba (Argentina); Durando, P.E. [Facultad de Ciencias Exactas, Fisicas y Naturales, Departamento de Biologia, Catedra de Fisiologia Animal, Universidad Nacional de San Juan, Complejo ' Islas Malvinas' , Av. Jose I. de la Roza y Meglioli, Rivadavia, San Juan (Argentina); Nores, M.L. [Facultad de Ciencias Medicas, Universidad Nacional de Cordoba-CONICET, Ciudad Universitaria, Cordoba (Argentina); Diaz, M.P. [Facultad de Ciencias Medicas, Catedra de Estadistica y Bioestadistica, Escuela de Nutricion, Universidad Nacional de Cordoba, Pabellon Chile, Ciudad Universitaria, 5000 Cordoba (Argentina); Bistoni, M.A., E-mail: mbistoni@com.uncor.ed [Facultad de Ciencias Exactas, Fisicas y Naturales, Catedra Diversidad Animal II, Universidad Nacional de Cordoba, Av. Velez Sarsfield 299, 5000 Cordoba (Argentina); Wunderlin, D.A. [Facultad de Ciencias Quimicas, Dto. Bioquimica Clinica-CIBICI, Universidad Nacional de Cordoba-CONICET, Haya de la Torre esq. Medina Allende, Ciudad Universitaria, 5000 Cordoba (Argentina)

2009-05-15

We assessed changes in spontaneous swimming activity and acetylcholinesterase (AchE) activity of Jenynsia multidentata exposed to Endosulfan (EDS). Females of J. multidentata were exposed to 0.072 and 1.4 mug L{sup -1} EDS. Average speed and movement percentage were recorded during 48 h. We also exposed females to EDS at five concentrations between 0.072 and 1.4 mug L{sup -1} during 24 h, and measured the AchE activity in brain and muscle. At 0.072 mug L{sup -1} EDS swimming motility decreased relative to the control group after 45 h, while at 1.4 mug L{sup -1} EDS swimming motility decreased after 24 h. AchE activity significantly decreased in muscle when J. multidentata were exposed to EDS above 0.072 mug L{sup -1}, while no significant changes were observed in brain. Thus, changes in swimming activity and AchE activity in muscle are good biomarkers of exposure to EDS in J. multidentata. - This work reports changes observed in spontaneous swimming activity and AchE activity of Jenynsia multidentata exposed to sublethal concentrations of Endosulfan.

BRCA1/2 mutation analysis in 41 ovarian cell lines reveals only one functionally deleterious BRCA1 mutation.

LENUS (Irish Health Repository)

Stordal, Britta

2013-06-01

Mutations in BRCA1\\/2 increase the risk of developing breast and ovarian cancer. Germline BRCA1\\/2 mutations occur in 8.6-13.7% of unselected epithelial ovarian cancers, somatic mutations are also frequent. BRCA1\\/2 mutated or dysfunctional cells may be sensitive to PARP inhibition by synthetic lethality. The aim of this study is to comprehensively characterise the BRCA1\\/2 status of a large panel of ovarian cancer cell lines available to the research community to assist in biomarker studies of novel drugs and in particular of PARP inhibitors. The BRCA1\\/2 genes were sequenced in 41 ovarian cell lines, mRNA expression of BRCA1\\/2 and gene methylation status of BRCA1 was also examined. The cytotoxicity of PARP inhibitors olaparib and veliparib was examined in 20 cell lines. The cell line SNU-251 has a deleterious BRCA1 mutation at 5564G > A, and is the only deleterious BRCA1\\/2 mutant in the panel. Two cell lines (UPN-251 and PEO1) had deleterious mutations as well as additional reversion mutations that restored the protein functionality. Heterozygous mutations in BRCA1\\/2 were relatively common, found in 14.6% of cell lines. BRCA1 was methylated in two cell lines (OVCAR8, A1847) and there was a corresponding decrease in gene expression. The BRCA1 methylated cell lines were more sensitive to PARP inhibition than wild-type cells. The SNU-251 deleterious mutant was more sensitive to PARP inhibition, but only in a long-term exposure to correct for its slow growth rate. Cell lines derived from metastatic disease are significantly more resistant to veliparib (2.0 fold p = 0.03) compared to those derived from primary tumours. Resistance to olaparib and veliparib was correlated Pearsons-R 0.5393, p = 0.0311. The incidence of BRCA1\\/2 deleterious mutations 1\\/41 cell lines derived from 33 different patients (3.0%) is much lower than the population incidence. The reversion mutations and high frequency of heterozygous mutations suggest that there is a selective

Maternal underweight and the risk of spontaneous abortion

DEFF Research Database (Denmark)

Helgstrand, Stine; Andersen, Anne-Marie Nybo

2005-01-01

BACKGROUND: To evaluate the risk of spontaneous abortion in relation to maternal pre-pregnant underweight. METHODS: The study was designed as a cohort study within the framework of the Danish National Birth Cohort (DNBC). The participants were a total of 23 821 women recruited consecutively...... spontaneous abortion. Relative risk of spontaneous abortion was calculated as Hazard Ratios using Cox regression with delayed entry. RESULTS: The outcome measure was spontaneous abortion. The hazard ratio for spontaneous abortion in women with a pre-pregnant body mass index (BMI) below 18.5 was 1.24 (95......% confidence limits 0.95-1.63) compared to women with pre-pregnant BMI 18.5-24.9. Women with a BMI of 25 or more had a smaller increase in risk of spontaneous abortion. Adjustment for maternal age, parity, previous miscarriages, and lifestyle factors did not affect the estimates substantially, neither did...

Novel Mutations in Synaptic Transmission Genes Suppress Neuronal Hyperexcitation in Caenorhabditis elegans

Directory of Open Access Journals (Sweden)

Katherine A. McCulloch

2017-07-01

Full Text Available Acetylcholine (ACh receptors (AChR regulate neural circuit activity in multiple contexts. In humans, mutations in ionotropic acetylcholine receptor (iAChR genes can cause neurological disorders, including myasthenia gravis and epilepsy. In Caenorhabditis elegans, iAChRs play multiple roles in the locomotor circuit. The cholinergic motor neurons express an ACR-2-containing pentameric AChR (ACR-2R comprised of ACR-2, ACR-3, ACR-12, UNC-38, and UNC-63 subunits. A gain-of-function mutation in the non-α subunit gene acr-2 [acr-2(gf] causes defective locomotion as well as spontaneous convulsions. Previous studies of genetic suppressors of acr-2(gf have provided insights into ACR-2R composition and assembly. Here, to further understand how the ACR-2R regulates neuronal activity, we expanded the suppressor screen for acr-2(gf-induced convulsions. The majority of these suppressor mutations affect genes that play critical roles in synaptic transmission, including two novel mutations in the vesicular ACh transporter unc-17. In addition, we identified a role for a conserved major facilitator superfamily domain (MFSD protein, mfsd-6, in regulating neural circuit activity. We further defined a role for the sphingosine (SPH kinase (Sphk sphk-1 in cholinergic neuron activity, independent of previously known signaling pathways. Overall, the genes identified in our study suggest that optimal modulation of synaptic activity is balanced by the differential activities of multiple pathways, and the novel alleles provide valuable reagents to further dissect neuronal mechanisms regulating the locomotor circuit.

Mutations in BALB mitochondrial DNA induce CCL20 up-regulation promoting tumorigenic phenotypes

Energy Technology Data Exchange (ETDEWEB)

Sligh, James [Department of Medicine—Dermatology Division, University of Arizona, Tucson, AZ 857 24 (United States); University of Arizona Cancer Center, Tucson, AZ 85724 (United States); Janda, Jaroslav [University of Arizona Cancer Center, Tucson, AZ 85724 (United States); Jandova, Jana, E-mail: jjandova@email.arizona.edu [Department of Medicine—Dermatology Division, University of Arizona, Tucson, AZ 857 24 (United States); University of Arizona Cancer Center, Tucson, AZ 85724 (United States)

2014-11-15

Highlights: • Alterations in mitochondrial DNA are commonly found in various human cancers. • Mutations in BALB mitochondrial DNA induce up-regulation of chemokine CCL20. • Increased growth and motility of mtBALB cells is associated with CCL20 levels. • mtDNA changes in BALB induce in vivo tumor growth through CCL20 up-regulation. • Mutations in mitochondrial DNA play important roles in keratinocyte neoplasia. - Abstract: mtDNA mutations are common in human cancers and are thought to contribute to the process of neoplasia. We examined the role of mtDNA mutations in skin cancer by generating fibroblast cybrids harboring a mutation in the gene encoding the mitochondrial tRNA for arginine. This somatic mutation (9821insA) was previously reported in UV-induced hyperkeratotic skin tumors in hairless mice and confers specific tumorigenic phenotypes to mutant cybrids. Microarray analysis revealed and RT-PCR along with Western blot analysis confirmed the up-regulation of CCL20 and its receptor CCR6 in mtBALB haplotype containing the mt-Tr 9821insA allele compared to wild type mtB6 haplotype. Based on reported role of CCL20 in cancer progression we examined whether the hyper-proliferation and enhanced motility of mtBALB haplotype would be associated with CCL20 levels. Treatment of both genotypes with recombinant CCL20 (rmCCL20) resulted in enhanced growth and motility of mtB6 cybrids. Furthermore, the acquired somatic alteration increased the in vivo tumor growth of mtBALB cybrids through the up-regulation of CCL20 since neutralizing antibody significantly decreased in vivo tumor growth of these cells; and tumors from anti-CCL20 treated mice injected with mtBALB cybrids showed significantly decreased CCL20 levels. When rmCCL20 or mtBALB cybrids were used as chemotactic stimuli, mtB6 cybrids showed increased motility while anti-CCL20 antibody decreased the migration and in vivo tumor growth of mtBALB cybrids. Moreover, the inhibitors of MAPK signaling and NF

Spontaneous deregulation

NARCIS (Netherlands)

Edelman, Benjamin; Geradin, Damien

Platform businesses such as Airbnb and Uber have risen to success partly by sidestepping laws and regulations that encumber their traditional competitors. Such rule flouting is what the authors call “spontaneous private deregulation,” and it’s happening in a growing number of industries. The authors

Use of spontaneously mutated human DNA as competitive internal standard for nucleic acid quantification by reverse transcription-polymerase chain reaction (RT-PCR)

International Nuclear Information System (INIS)

Rudnicka, L.; Diaz, A.; Varga, J.; Jimenez, S.A.; Christiano, A.; Uitto, J.

1995-01-01

Quantification of gene expression is of increasing interest in many medical sciences. Methods based on reverse transcription-polymerase chain reactions (RT-PCRs) are timesaving and require only very small amounts of RNA. A limiting factor, however, is the significant fluctuation in the efficacy of reverse transcription as well in the polymerase chain reactions. Various external and internal standards have been suggested for correcting these fluctuations. We describe a novel way of creating an internal standard for assessing the expression of type VII collagen in human cells. The total RNA of a patient with hereditary 'epidermilysis bulosa dystrophica' associated with a homozygous T to A point mutation in type VII collagen gene was reverse transcribed and a 382bp fragment of type VII collagen cDNA containing the mutation was amplified. The mutated cDNA, unlike normal type VII collagen cDNA could be cleaved by 'Ear I' endonuclease into 244bp and 138bp fragments. Semiquantitative PCR was performed with the mutated cDNA as internal standard and the studied cDNA sample in the same tube in the presence of α 32 P-labelled dCTP. The reaction was followed by 'Ear I' digestion, electrophoresis on a polyacrylamide gel and exposure to a X-ray film. In conclusion, we describe a timesaving method for creating internal standards for semiquantitative RT-PCR. (author). 12 refs, 3 figs

Bias in spontaneous reporting of adverse drug reactions in Japan.

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Shinichi Matsuda

Full Text Available Attitudes of healthcare professionals regarding spontaneous reporting of adverse drug reactions (ADRs in Japan are not well known, and Japan's unique system of surveillance, called early post-marketing phase vigilance (EPPV, may affect these reporting attitudes. Our objectives were to describe potential effects of EPPV and to test whether ADR seriousness, prominence, and frequency are related to changes in reporting over time.A manufacturer's database of spontaneous ADR reports was used to extract data from individual case safety reports for 5 drugs subject to EPPV. The trend of reporting and the time lag between ADR onset and reporting to the manufacturer were examined. The following indices for ADRs occurring with each drug were calculated and analyzed to assess reporting trends: Serious:Non-serious ratio, High prominence:Low prominence ratio, and High frequency:Low frequency ratio.For all 5 drugs, the time lag between ADR onset and reporting to the manufacturer was shorter in the EPPV period than in the post-EPPV period. All drugs showed higher Serious:Non-serious ratios in the post-EPPV period. No specific patterns were observed for the High prominence:Low prominence ratio. The High frequency:Low frequency ratio for peginterferon alpha-2a and sevelamer hydrochloride decreased steadily throughout the study period.Healthcare professionals may be more likely to report serious ADRs than to report non-serious ADRs, but the effect of event prominence on reporting trends is still unclear. Factors associated with ADR reporting attitude in Japan might be different from those in other countries because of EPPV and the involvement of medical representatives in the spontaneous reporting process. Pharmacovigilance specialists should therefore be cautious when comparing data between different time periods or different countries. Further studies are needed to elucidate the underlying mechanism of spontaneous ADR reporting in Japan.

Presbycusis Disrupts Spontaneous Activity Revealed by Resting-State Functional MRI

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Yu-Chen Chen

2018-03-01

Full Text Available Purpose: Presbycusis, age-related hearing loss, is believed to involve neural changes in the central nervous system, which is associated with an increased risk of cognitive impairment. The goal of this study was to determine if presbycusis disrupted spontaneous neural activity in specific brain areas involved in auditory processing, attention and cognitive function using resting-state functional magnetic resonance imaging (fMRI approach.Methods: Hearing and resting-state fMRI measurements were obtained from 22 presbycusis patients and 23 age-, sex- and education-matched healthy controls. To identify changes in spontaneous neural activity associated with age-related hearing loss, we compared the amplitude of low-frequency fluctuations (ALFF and regional homogeneity (ReHo of fMRI signals in presbycusis patients vs. controls and then determined if these changes were linked to clinical measures of presbycusis.Results: Compared with healthy controls, presbycusis patients manifested decreased spontaneous activity mainly in the superior temporal gyrus (STG, parahippocampal gyrus (PHG, precuneus and inferior parietal lobule (IPL as well as increased neural activity in the middle frontal gyrus (MFG, cuneus and postcentral gyrus (PoCG. A significant negative correlation was observed between ALFF/ReHo activity in the STG and average hearing thresholds in presbycusis patients. Increased ALFF/ReHo activity in the MFG was positively correlated with impaired Trail-Making Test B (TMT-B scores, indicative of impaired cognitive function involving the frontal lobe.Conclusions: Presbycusis patients have disrupted spontaneous neural activity reflected by ALFF and ReHo measurements in several brain regions; these changes are associated with specific cognitive performance and speech/language processing. These findings mainly emphasize the crucial role of aberrant resting-state ALFF/ReHo patterns in presbycusis patients and will lead to a better understanding of the

Presbycusis Disrupts Spontaneous Activity Revealed by Resting-State Functional MRI.

Science.gov (United States)

Chen, Yu-Chen; Chen, Huiyou; Jiang, Liang; Bo, Fan; Xu, Jin-Jing; Mao, Cun-Nan; Salvi, Richard; Yin, Xindao; Lu, Guangming; Gu, Jian-Ping

2018-01-01

Purpose : Presbycusis, age-related hearing loss, is believed to involve neural changes in the central nervous system, which is associated with an increased risk of cognitive impairment. The goal of this study was to determine if presbycusis disrupted spontaneous neural activity in specific brain areas involved in auditory processing, attention and cognitive function using resting-state functional magnetic resonance imaging (fMRI) approach. Methods : Hearing and resting-state fMRI measurements were obtained from 22 presbycusis patients and 23 age-, sex- and education-matched healthy controls. To identify changes in spontaneous neural activity associated with age-related hearing loss, we compared the amplitude of low-frequency fluctuations (ALFF) and regional homogeneity (ReHo) of fMRI signals in presbycusis patients vs. controls and then determined if these changes were linked to clinical measures of presbycusis. Results : Compared with healthy controls, presbycusis patients manifested decreased spontaneous activity mainly in the superior temporal gyrus (STG), parahippocampal gyrus (PHG), precuneus and inferior parietal lobule (IPL) as well as increased neural activity in the middle frontal gyrus (MFG), cuneus and postcentral gyrus (PoCG). A significant negative correlation was observed between ALFF/ReHo activity in the STG and average hearing thresholds in presbycusis patients. Increased ALFF/ReHo activity in the MFG was positively correlated with impaired Trail-Making Test B (TMT-B) scores, indicative of impaired cognitive function involving the frontal lobe. Conclusions : Presbycusis patients have disrupted spontaneous neural activity reflected by ALFF and ReHo measurements in several brain regions; these changes are associated with specific cognitive performance and speech/language processing. These findings mainly emphasize the crucial role of aberrant resting-state ALFF/ReHo patterns in presbycusis patients and will lead to a better understanding of the

Amlodipine decreases fibrosis and cardiac hypertrophy in spontaneously hypertensive rats: persistent effects after withdrawal.

Science.gov (United States)

Sevilla, María A; Voces, Felipe; Carrón, Rosalía; Guerrero, Estela I; Ardanaz, Noelia; San Román, Luis; Arévalo, Miguel A; Montero, María J

2004-07-02

Our objective was to examine the effect of chronic treatment with amlodipine on blood pressure, left ventricular hypertrophy, and fibrosis in spontaneously hypertensive rats and the persistence of such an effect after drug withdrawal. We investigated the effects of treatment with 2, 8 and 20 mg/kg/day of amlodipine given orally for six months and at three months after drug withdrawal. Systolic blood pressure was measured using the tail-cuff method. At the end of the study period, the heart was excised, the left ventricle was isolated, and the left ventricle weight/body weight ratio was calculated as a left ventricular hypertrophy index. Fibrosis, expressed as collagen volume fraction, was evaluated using an automated image-analysis system on sections stained with Sirius red. Age-matched untreated Wistar-Kyoto and SHR were used as normotensive and hypertensive controls, respectively. Systolic blood pressure was reduced in the treated SHR in a dose-dependent way and after amlodipine withdrawal it increased progressively, without reaching the values of the hypertensive controls. Cardiac hypertrophy was reduced by 8 and 20 mg/kg/day amlodipine, but when treatment was withdrawn only the group treated with 8 mg/kg/day maintained significant differences versus the hypertensive controls. All three doses of amlodipine reduced cardiac fibrosis and this regression persisted with the two highest doses after three months without treatment. We concluded that antihypertensive treatment with amlodipine is accompanied by a reduction in left ventricular hypertrophy and regression in collagen deposition. Treatment was more effective in preventing fibrosis than in preventing ventricular hypertrophy after drug withdrawal. Copyright 2004 Elsevier Inc.

Biological effects of dyes on bacteria. VI. Mutation induction by acridine orange and methylene blue in the dark with special reference to Escherichia coli WP6 (polA1)

Energy Technology Data Exchange (ETDEWEB)

Webb, R.B.; Hass, B.S.

1984-01-01

Acridine orange (AO) and methylene blue (MB) in the dark were shown to be weak to moderate mutagens (induction of resistance to T5 phage) in repair-deficient strains of Escherichia coli B/r. However, strain WP2, (wild-type) was not mutated by AO in the dark, in confirmation of earlier data. The presence of 2 ..mu..M AO reduced by 41% the spontaneous mutation rate in strain WP2, from 4.1 to 2.4 mutants/10/sup 8/ cells/generation. In the polymerase I-deficient strain WP6 (polA1), 2 ..mu..M AO increased the mutation rate in the dark 14-fold. It is proposed that both spontaneous and AO-induced mutagenesis in the absence of light occur at the site of semiconservative DNA replication. If the intercalation mechanism for the effects in the absence of light is valid, the wild-type strain (WP2) may be resistant to frameshift mutagenesis induced by intercalated compounds, while the polymerase I-deficient strain (WP6) may be highly susceptible to the presence of an intercalated dye such as AO at the DNA-replication fork. MB and AO likely act through different mechanisms since MB is only a moderate mutagen in strain WP6 and the other repair-deficient strains tested.

Hemochromatosis (HFE gene mutations in Brazilian chronic hemodialysis patients

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F.V. Perícole

2005-09-01

Full Text Available Patients with chronic renal insufficiency (CRI have reduced hemoglobin levels, mostly as a result of decreased kidney production of erythropoietin, but the relation between renal insufficiency and the magnitude of hemoglobin reduction has not been well defined. Hereditary hemochromatosis is an inherited disorder of iron metabolism. The importance of the association of hemochromatosis with treatment for anemia among patients with CRI has not been well described. We analyzed the frequency of the C282Y and H63D mutations in the HFE gene in 201 Brazilian individuals with CRI undergoing hemodialysis. The analysis of the effects of HFE mutations on iron metabolism and anemia with biochemical parameters was possible in 118 patients of this study (hemoglobin, hematocrit, ferritin levels, transferrin saturation, and serum iron. A C282Y heterozygous mutation was found in 7/201 (3.4% and H63D homozygous and heterozygous mutation were found in 2/201 (1.0% and 46/201 (22.9%, respectively. The allelic frequencies of the HFE mutations (0.017 for C282Y mutation and 0.124 for H63D mutation did not differ between patients with CRI and healthy controls. Regarding the biochemical parameters, no differences were observed between HFE heterozygous and mutation-negative patients, although ferritin levels were not higher among patients with the H63D mutation (P = 0.08. From what we observed in our study, C282Y/H63D HFE gene mutations are not related to degrees of anemia or iron stores in CRI patients receiving intravenous iron supplementation (P > 0.10. Nevertheless, the present data suggest that the H63D mutation may have an important function as a modulating factor of iron overload in these patients.

In vivo somatic mutation systems in the mouse

International Nuclear Information System (INIS)

Russell, L.B.

1979-01-01

In an effort to meet the need for a fast and cheap in vivo prescreen for inherited mammalian point mutations, a somatic forward-mutation method, originally developed in an x-ray experiment, has more recently been tested in work with chemical mutagens. The method makes use of coat-color mutations because the gene product is usually locally expressed, mosaics can be detected with minimal effort, and opportunities for making comparison with induction of germinal point mutations are greatest.--Following treatment of embryos that are heterozygous at specific coat-color loci, various induced genetic changes can result in expression of the recessive (RS) in clones derived from mutant melanocyte precursor cells. However, other events, such as decrease in the number of precursor cells, or disturbed differentiation, can also result in spots, which with careful classification can usually be distinguished from RS's on the basis of their location and color. When this is done, the relative RS frequencies for a series of compounds at least roughly parallel the relative spermatogonial mutation rates. The fact that easily measurable (though low) RS rates are obtained with compounds that have yielded negative results in spermatogonial tests is not surprising in view of the fact that RS's can be caused by several mechanisms besides point mutation.--In spite of the parallelism observed in one laboratory, the usefulness of the in vivo somatic mutation method as a prescreen could come to be doubted because of major discrepancies between results of similar experiments at different laboratories. However, It appears probable that at least some of these discrepancies are due to failure to discriminate between spots that probably resulted from melanocyte insufficiency and spots that resulted from expression of the recessive.--Reverse somatic mutation systems can potentially avoid some of the pitfalls of forward mutation systems. Such system are still in developmental stages

Ultraviolet light protection, enhancement of ultraviolet light mutagenesis, and mutator effect of plasmid R46 in Salmonella typhimurium

International Nuclear Information System (INIS)

Mortelmans, K.E.; Stocker, B.A.D.

1976-01-01

Plasmid R46 partially protected Salmonella typhimurium, wild type or uvrB or polA, against the lethal effect of ultraviolet (uv) irradiation, but did not protect recA mutants. The plasmid also increased frequency of uv-induced reversion to His + in all tested his point mutants (wild type for uv sensitivity), including amber, ochre, UGA, missense, and frame-shift mutants. Plasmid R46 also increased uv-induced reversion to His + in uvrB and polA strains, but no uv mutagenic effect was detected in R - or R46-carrying recA derivatives of a his(amber) mutant. The spontaneous reversion frequency of his nonsense mutants of all classes, and of some his missense mutants, was increased about 10-fold when the strains carried R46, but the plasmid had no effect on the spontaneous reversion frequency of some other his missense mutations or of reversion rate of his frame-shift mutants (except for two uvrB derivatives of one single-base insertion mutant). The plasmid increased the ability of wild type, polA, and uvrB hosts to support plaque production by uv-irradiated phage, and made strain LT2 his G46 less sensitive to methyl methane sulfonate and to x rays and more responsive to the mutagenic effect of visible-light irradiation. R46 increased spontaneous reversion frequency of a his(amber) rec + strain, but had no such effect in its recA sublines. Since the plasmid in the absence of host recA function fails to produce its mutator effect, or to confer uv protection or to enhance uv mutagenesis, these three effects may be produced via some mechanism involved in recA-dependent deoxyribonucleic acid repair, perhaps by an increase in activity of the ''error-prone'' component of the inducible repair pathway

Characteristics and mutation analysis of Ph-positive leukemia patients with T315I mutation receiving tyrosine kinase inhibitors

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Xu PP

2017-09-01

Full Text Available Peipei Xu,1 Dan Guo,2 Xiaoyan Shao,1 Miaoxin Peng,1 Bing Chen2 1Department of Hematology, Drum Tower Hospital, School of Medicine, Nanjing University, 2Department of Hematology, Nanjing Drum Tower Hospital Clinical College of Nanjing Medical University, Nanjing, People’s Republic of China Background: TKIs are the first-line treatment for patients with Ph-positive (Ph+ leukemia. However, drug resistance is frequently observed, mainly due to mutations within the breakpoint cluster region-Abelson leukemia virus (BCR-ABL kinase domain. The T315I substitution confers complete resistance to TKIs. The aim of this study was to analyze the clinical characteristics of 17 patients with T315I mutation after TKI treatment and provide a basis for prognosis.Patients and methods: The clinical data of 17 TKI-resistant Ph+ leukemia patients who were found to have a ABL kinase domain mutation from September 2008 to January 2017 were collected. Karyotypes and BCR-ABL fusion gene were analyzed by R-banding and fluorescence in situ hybridization, respectively. Total RNA was extracted by TRIzol reagent, and the ABL kinase domain mutation was detected by direct sequencing.Results: A total of 17 patients reached effective remission including major molecular response and complete cytogenetic response. However, all the patients subsequently developed a T315I mutation after treatment with TKIs. The rate of the BCR-ABL fusion gene in most of the patients who developed the T315I mutation was significantly higher than that before the mutation. At initial diagnosis, patients average platelet count was 149.7×109/L, whereas the average platelet count was only 53.88×109/L after the T315I mutation (P<0.01. The results also showed that the survival time of patients with a high proportion of blast cells or a high number of white blood cells was obviously shortened.Conclusion: Patients platelet count decreased when detected with the T315I mutation compared with the initial

Quantifying emissions from spontaneous combustion

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-09-01

Spontaneous combustion can be a significant problem in the coal industry, not only due to the obvious safety hazard and the potential loss of valuable assets, but also with respect to the release of gaseous pollutants, especially CO2, from uncontrolled coal fires. This report reviews methodologies for measuring emissions from spontaneous combustion and discusses methods for quantifying, estimating and accounting for the purpose of preparing emission inventories.

Reduced Penetrance and Variable Expression of SCN5A Mutations and the Importance of Co-inherited Genetic Variants: Case Report and Review of the Literature

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T. Robyns, MD.

2014-05-01

Full Text Available Mutations in the SCN5A gene are responsible for multiple phenotypical presentations including Brugada syndrome, long QT syndrome, progressive familial heart block, sick sinus syndrome, dilated cardiomyopathy, lone atrial fibrillation and multiple overlap syndromes. These different phenotypic expressions of a mutation in a single gene can be explained by variable expression and reduced penetrance. One of the possible explanations of these phenomena is the co-inheritance of genetic variants. We describe a family where the individuals exhibit a compound heterozygosity in the SCN5A gene including a mutation (R1632H and a new variant (M858L. Individuals with both the mutation and new variant present with a more severe phenotype including spontaneous atrial tachyarrhythmia at young age. We give an overview of the different phenotypes of "SCN5A disease" and discuss the importance of co-inherited genetic variants in the expression of SCN5A disease.

Comparison of spontaneous vs. metronome-guided breathing on assessment of vagal modulation using RR variability.

Science.gov (United States)

Bloomfield, D M; Magnano, A; Bigger, J T; Rivadeneira, H; Parides, M; Steinman, R C

2001-03-01

R-R interval variability (RR variability) is increasingly being used as an index of autonomic activity. High-frequency (HF) power reflects vagal modulation of the sinus node. Since vagal modulation occurs at the respiratory frequency, some investigators have suggested that HF power cannot be interpreted unless the breathing rate is controlled. We hypothesized that HF power during spontaneous breathing would not differ significantly from HF power during metronome-guided breathing. We measured HF power during spontaneous breathing in 20 healthy subjects and 19 patients with heart disease. Each subject's spontaneous breathing rate was determined, and the calculation of HF power was repeated with a metronome set to his or her average spontaneous breathing rate. There was no significant difference between the logarithm of HF power measured during spontaneous and metronome-guided breathing [4.88 +/- 0.29 vs. 5.29 +/- 0.30 ln(ms(2)), P = 0.32] in the group as a whole and when patients and healthy subjects were examined separately. We did observe a small (9.9%) decrease in HF power with increasing metronome-guided breathing rates (from 9 to 20 breaths/min). These data indicate that HF power during spontaneous and metronome-guided breathing differs at most by very small amounts. This variability is several logarithmic units less than the wide discrepancies observed between healthy subjects and cardiac patients with a heterogeneous group of cardiovascular disorders. In addition, HF power is relatively constant across the range of typical breathing rates. These data indicate that there is no need to control breathing rate to interpret HF power when RR variability (and specifically HF power) is used to identify high-risk cardiac patients.

Somatic mosaicism containing double mutations in PTCH1 revealed by generation of induced pluripotent stem cells from nevoid basal cell carcinoma syndrome.

Science.gov (United States)

Ikemoto, Yu; Takayama, Yoshinaga; Fujii, Katsunori; Masuda, Mokuri; Kato, Chise; Hatsuse, Hiromi; Fujitani, Kazuko; Nagao, Kazuaki; Kameyama, Kohzoh; Ikehara, Hajime; Toyoda, Masashi; Umezawa, Akihiro; Miyashita, Toshiyuki

2017-08-01

Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominant disorder characterised by developmental defects and tumorigenesis, such as medulloblastomas and basal cell carcinomas, caused by mutations of the patched-1 ( PTCH1 ) gene. In this article, we seek to demonstrate a mosaicism containing double mutations in PTCH1 in an individual with NBCCS. A de novo germline mutation of PTCH1 (c.272delG) was detected in a 31-year-old woman with NBCCS. Gene analysis of two out of four induced pluripotent stem cell (iPSC) clones established from the patient unexpectedly revealed an additional mutation, c.274delT. Deep sequencing confirmed a low-prevalence somatic mutation (5.5%-15.6% depending on the tissue) identical to the one found in iPSC clones. This is the first case of mosaicism unequivocally demonstrated in NBCCS. Furthermore, the mosaicism is unique in that the patient carries one normal and two mutant alleles. Because these mutations are located in close proximity, reversion error is likely to be involved in this event rather than a spontaneous mutation. In addition, this study indicates that gene analysis of iPSC clones can contribute to the detection of mosaicism containing a minor population carrying a second mutation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The Arctic Alzheimer mutation enhances sensitivity to toxic stress in human neuroblastoma cells

DEFF Research Database (Denmark)

Sennvik, Kristina; Nilsberth, Camilla; Stenh, Charlotte

2002-01-01

The E693G (Arctic) mutation of the amyloid precursor protein was recently found to lead to early-onset Alzheimer's disease in a Swedish family. In the present study, we report that the Arctic mutation decreases cell viability in human neuroblastoma cells. The cell viability, as measured by the MTT...... their secretion of beta-secretase cleaved amyloid precursor protein. The enhanced sensitivity to toxic stress in cells with the Arctic mutation most likely contributes to the pathogenic pathway leading to Alzheimer's disease....

Spontaneous shaker rat mutant – a new model for X-linked tremor/ataxia

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Karla P. Figueroa

2016-05-01

Full Text Available The shaker rat is an X-linked recessive spontaneous model of progressive Purkinje cell (PC degeneration exhibiting a shaking ataxia and wide stance. Generation of Wistar Furth (WF/Brown Norwegian (BN F1 hybrids and genetic mapping of F2 sib-sib offspring using polymorphic markers narrowed the candidate gene region to 26 Mbp denoted by the last recombinant genetic marker DXRat21 at 133 Mbp to qter (the end of the long arm. In the WF background, the shaker mutation has complete penetrance, results in a stereotypic phenotype and there is a narrow window for age of disease onset; by contrast, the F2 hybrid phenotype was more varied, with a later age of onset and likely non-penetrance of the mutation. By deep RNA-sequencing, five variants were found in the candidate region; four were novel without known annotation. One of the variants caused an arginine (R to cysteine (C change at codon 35 of the ATPase, Ca2+ transporting, plasma membrane 3 (Atp2b3 gene encoding PMCA3 that has high expression in the cerebellum. The variant was well supported by hundreds of overlapping reads, and was found in 100% of all affected replicas and 0% of the wild-type (WT replicas. The mutation segregated with disease in all affected animals and the amino acid change was found in an evolutionarily conserved region of PMCA3. Despite strong genetic evidence for pathogenicity, in vitro analyses of PMCA3R35C function did not show any differences to WT PMCA3. Because Atp2b3 mutation leads to congenital ataxia in humans, the identified Atp2b3 missense change in the shaker rat presents a good candidate for the shaker rat phenotype based on genetic criteria, but cannot yet be considered a definite pathogenic variant owing to lack of functional changes.

Spontaneous shaker rat mutant – a new model for X-linked tremor/ataxia

Science.gov (United States)

Figueroa, Karla P.; Paul, Sharan; Calì, Tito; Lopreiato, Raffaele; Karan, Sukanya; Frizzarin, Martina; Ames, Darren; Zanni, Ginevra; Brini, Marisa; Dansithong, Warunee; Milash, Brett; Scoles, Daniel R.; Carafoli, Ernesto; Pulst, Stefan M.

2016-01-01

ABSTRACT The shaker rat is an X-linked recessive spontaneous model of progressive Purkinje cell (PC) degeneration exhibiting a shaking ataxia and wide stance. Generation of Wistar Furth (WF)/Brown Norwegian (BN) F1 hybrids and genetic mapping of F2 sib-sib offspring using polymorphic markers narrowed the candidate gene region to 26 Mbp denoted by the last recombinant genetic marker DXRat21 at 133 Mbp to qter (the end of the long arm). In the WF background, the shaker mutation has complete penetrance, results in a stereotypic phenotype and there is a narrow window for age of disease onset; by contrast, the F2 hybrid phenotype was more varied, with a later age of onset and likely non-penetrance of the mutation. By deep RNA-sequencing, five variants were found in the candidate region; four were novel without known annotation. One of the variants caused an arginine (R) to cysteine (C) change at codon 35 of the ATPase, Ca2+ transporting, plasma membrane 3 (Atp2b3) gene encoding PMCA3 that has high expression in the cerebellum. The variant was well supported by hundreds of overlapping reads, and was found in 100% of all affected replicas and 0% of the wild-type (WT) replicas. The mutation segregated with disease in all affected animals and the amino acid change was found in an evolutionarily conserved region of PMCA3. Despite strong genetic evidence for pathogenicity, in vitro analyses of PMCA3R35C function did not show any differences to WT PMCA3. Because Atp2b3 mutation leads to congenital ataxia in humans, the identified Atp2b3 missense change in the shaker rat presents a good candidate for the shaker rat phenotype based on genetic criteria, but cannot yet be considered a definite pathogenic variant owing to lack of functional changes. PMID:27013529

The effect of pre-mutation of X chromosome CGG trinucleotide repeats on brain anatomy.

Science.gov (United States)

Moore, Caroline J; Daly, Eileen M; Tassone, Flora; Tysoe, Carolyn; Schmitz, Nicole; Ng, Virginia; Chitnis, Xavier; McGuire, Philip; Suckling, John; Davies, Kay E; Hagerman, Randi J; Hagerman, Paul J; Murphy, Kieran C; Murphy, Declan G M

2004-12-01

Expanded trinucleotide repeats are associated with several neuropsychiatric disorders, including fragile X syndrome (FraX) which is the most common inherited form of mental retardation. It is currently thought that FraX results from having >200 CGG trinucleotide repeats, with consequent methylation of the fragile X mental retardation gene (FMR1) and loss of FMR1 protein (FMRP). Pre-mutation carriers of FraX (with 55-200 CGG trinucleotide repeats) were originally considered unaffected, although recent studies challenge this view. However, there are few studies on the effect of pre-mutation trinucleotide repeat expansion on the male human brain using quantitative MRI. Also the results of prior investigations may be confounded because people were selected on the basis of clinical and neurological features, and not genetic phenotype. We compared the brain anatomy of 20 adult male pre-mutation members of known FraX families with 20 healthy male controls. The two groups did not differ significantly in age, intelligence quotient (IQ) or handedness. We also investigated whether any observed effects were associated with: (i) ageing; (ii) expansion of pre-mutation CGG trinucleotide repeats; (iii) reduction in the percentage of lymphocytes staining with anti-FMRP antibodies [%FMRP(+) lymphocytes]; and (iv) elevation of FMR1 mRNA levels. Male pre-mutation carriers of FraX, compared with matched controls, had significantly less voxel density in several brain regions, including the cerebellum, amygdalo-hippocampal complex and thalamus. Within pre-mutation carriers of FraX, ageing, increases in the number of CGG trinucleotide repeats and decreases in %FMRP(+) lymphocytes were associated with decreasing voxel density of regions previously identified as decreased relative to controls. Regional grey and white matter density is significantly affected in male pre-mutation carriers of FraX recruited on the basis of genetic, not clinical, phenotype. The association of voxel density

Oscillatory brain activity in spontaneous and induced sleep stages in flies.

Science.gov (United States)

Yap, Melvyn H W; Grabowska, Martyna J; Rohrscheib, Chelsie; Jeans, Rhiannon; Troup, Michael; Paulk, Angelique C; van Alphen, Bart; Shaw, Paul J; van Swinderen, Bruno

2017-11-28

Sleep is a dynamic process comprising multiple stages, each associated with distinct electrophysiological properties and potentially serving different functions. While these phenomena are well described in vertebrates, it is unclear if invertebrates have distinct sleep stages. We perform local field potential (LFP) recordings on flies spontaneously sleeping, and compare their brain activity to flies induced to sleep using either genetic activation of sleep-promoting circuitry or the GABA A agonist Gaboxadol. We find a transitional sleep stage associated with a 7-10 Hz oscillation in the central brain during spontaneous sleep. Oscillatory activity is also evident when we acutely activate sleep-promoting neurons in the dorsal fan-shaped body (dFB) of Drosophila. In contrast, sleep following Gaboxadol exposure is characterized by low-amplitude LFPs, during which dFB-induced effects are suppressed. Sleep in flies thus appears to involve at least two distinct stages: increased oscillatory activity, particularly during sleep induction, followed by desynchronized or decreased brain activity.

Monotonicity of fitness landscapes and mutation rate control.

Science.gov (United States)

Belavkin, Roman V; Channon, Alastair; Aston, Elizabeth; Aston, John; Krašovec, Rok; Knight, Christopher G

2016-12-01

A common view in evolutionary biology is that mutation rates are minimised. However, studies in combinatorial optimisation and search have shown a clear advantage of using variable mutation rates as a control parameter to optimise the performance of evolutionary algorithms. Much biological theory in this area is based on Ronald Fisher's work, who used Euclidean geometry to study the relation between mutation size and expected fitness of the offspring in infinite phenotypic spaces. Here we reconsider this theory based on the alternative geometry of discrete and finite spaces of DNA sequences. First, we consider the geometric case of fitness being isomorphic to distance from an optimum, and show how problems of optimal mutation rate control can be solved exactly or approximately depending on additional constraints of the problem. Then we consider the general case of fitness communicating only partial information about the distance. We define weak monotonicity of fitness landscapes and prove that this property holds in all landscapes that are continuous and open at the optimum. This theoretical result motivates our hypothesis that optimal mutation rate functions in such landscapes will increase when fitness decreases in some neighbourhood of an optimum, resembling the control functions derived in the geometric case. We test this hypothesis experimentally by analysing approximately optimal mutation rate control functions in 115 complete landscapes of binding scores between DNA sequences and transcription factors. Our findings support the hypothesis and find that the increase of mutation rate is more rapid in landscapes that are less monotonic (more rugged). We discuss the relevance of these findings to living organisms.

Neurodevelopmental disease-associated de novo mutations and rare sequence variants affect TRIO GDP/GTP exchange factor activity.

Science.gov (United States)

Katrancha, Sara M; Wu, Yi; Zhu, Minsheng; Eipper, Betty A; Koleske, Anthony J; Mains, Richard E

2017-12-01

Bipolar disorder, schizophrenia, autism and intellectual disability are complex neurodevelopmental disorders, debilitating millions of people. Therapeutic progress is limited by poor understanding of underlying molecular pathways. Using a targeted search, we identified an enrichment of de novo mutations in the gene encoding the 330-kDa triple functional domain (TRIO) protein associated with neurodevelopmental disorders. By generating multiple TRIO antibodies, we show that the smaller TRIO9 isoform is the major brain protein product, and its levels decrease after birth. TRIO9 contains two guanine nucleotide exchange factor (GEF) domains with distinct specificities: GEF1 activates both Rac1 and RhoG; GEF2 activates RhoA. To understand the impact of disease-associated de novo mutations and other rare sequence variants on TRIO function, we utilized two FRET-based biosensors: a Rac1 biosensor to study mutations in TRIO (T)GEF1, and a RhoA biosensor to study mutations in TGEF2. We discovered that one autism-associated de novo mutation in TGEF1 (K1431M), at the TGEF1/Rac1 interface, markedly decreased its overall activity toward Rac1. A schizophrenia-associated rare sequence variant in TGEF1 (F1538Intron) was substantially less active, normalized to protein level and expressed poorly. Overall, mutations in TGEF1 decreased GEF1 activity toward Rac1. One bipolar disorder-associated rare variant (M2145T) in TGEF2 impaired inhibition by the TGEF2 pleckstrin-homology domain, resulting in dramatically increased TGEF2 activity. Overall, genetic damage to both TGEF domains altered TRIO catalytic activity, decreasing TGEF1 activity and increasing TGEF2 activity. Importantly, both GEF changes are expected to decrease neurite outgrowth, perhaps consistent with their association with neurodevelopmental disorders. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

A mutation in the nucleoporin-107 gene causes XX gonadal dysgenesis.

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Weinberg-Shukron, Ariella; Renbaum, Paul; Kalifa, Rachel; Zeligson, Sharon; Ben-Neriah, Ziva; Dreifuss, Amatzia; Abu-Rayyan, Amal; Maatuk, Noa; Fardian, Nilly; Rekler, Dina; Kanaan, Moien; Samson, Abraham O; Levy-Lahad, Ephrat; Gerlitz, Offer; Zangen, David

2015-11-02

Ovarian development and maintenance are poorly understood; however, diseases that affect these processes can offer insights into the underlying mechanisms. XX female gonadal dysgenesis (XX-GD) is a rare, genetically heterogeneous disorder that is characterized by underdeveloped, dysfunctional ovaries, with subsequent lack of spontaneous pubertal development, primary amenorrhea, uterine hypoplasia, and hypergonadotropic hypogonadism. Here, we report an extended consanguineous family of Palestinian origin, in which 4 females exhibited XX-GD. Using homozygosity mapping and whole-exome sequencing, we identified a recessive missense mutation in nucleoporin-107 (NUP107, c.1339G>A, p.D447N). This mutation segregated with the XX-GD phenotype and was not present in available databases or in 150 healthy ethnically matched controls. NUP107 is a component of the nuclear pore complex, and the NUP107-associated protein SEH1 is required for oogenesis in Drosophila. In Drosophila, Nup107 knockdown in somatic gonadal cells resulted in female sterility, whereas males were fully fertile. Transgenic rescue of Drosophila females bearing the Nup107D364N mutation, which corresponds to the human NUP107 (p.D447N), resulted in almost complete sterility, with a marked reduction in progeny, morphologically aberrant eggshells, and disintegrating egg chambers, indicating defective oogenesis. These results indicate a pivotal role for NUP107 in ovarian development and suggest that nucleoporin defects may play a role in milder and more common conditions such as premature ovarian failure.

Mutation Spectrum and Phenotypic Features in Noonan Syndrome with PTPN11 Mutations: Definition of Two Novel Mutations.

Science.gov (United States)

Atik, Tahir; Aykut, Ayca; Hazan, Filiz; Onay, Huseyin; Goksen, Damla; Darcan, Sukran; Tukun, Ajlan; Ozkinay, Ferda

2016-06-01

To evaluate the spectrum of PTPN11 gene mutations in Noonan syndrome patients and to study the genotype-phenotype associations. In this study, twenty Noonan syndrome patients with PTPN11 mutations were included. The patients underwent a detailed clinical and physical evaluation. To identify inherited cases, parents of all mutation positive patients were analyzed. Thirteen different PTPN11 mutations, two of them being novel, were detected in the study group. These mutations included eleven missense mutations: p.G60A, p.D61N, p.Y62D, p.Y63C, p.E69Q, p.Q79R, p.Y279C,p.N308D, p.N308S, p.M504V, p.Q510R and two novel missense mutations: p.I56V and p.I282M. The frequency of cardiac abnormalities and short stature were found to be 80 % and 80 %, respectively. Mental retardation was not observed in patients having exon 8 mutations. No significant correlations were detected between other phenotypic features and genotypes. By identifying genotype-phenotype correlations, this study provides information on phenotypes observed in NS patients with different PTPN11 mutations.

Spontaneous calf haematoma: case report.

Science.gov (United States)

Zubaidah, N H; Liew, N C

2014-02-01

Spontaneous calf haematoma is a rare condition and few case reports have been published in the English literature. Common conditions like deep vein thrombosis and traumatic gastrocnemius muscle tear need to be considered when a patient presents with unilateral calf swelling and tenderness. Ultrasound and Magnetic Resonance Imaging are essential for confirmation of diagnosis. The purpose of this paper is to report on a rare case of spontaneous calf hematoma and its diagnosis and management.

BIOCHEMICAL AND HISTOLOGICAL EFFECTS OF TETRACYCLINES ON SPONTANEOUS OSTEOARTHRITIS IN GUINEA PIGS

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Edin De Bri

2011-05-01

Full Text Available Matrix metalloproteinases (MMPs are mediators in connective tissue destruction in a variety of pathologic processes. Recently discovered chemically modified tetracyclines have been found to be effective inhibitors of MMP mediated connective tissue degradation in both rheumatoid arthritis (RA and osteoarthritis (OA. The Hartley guinea pig model has been described with a high incidence of spontaneous OA-like changes in the knee joint. Therefore we have studied the effect of two tetracyclines, doxycycline (Dox and chemically modified tetracycline-7 (CMT-7 which have both previously been shown as potent MMP inhibitors. We found that prophylactic orally given CMT-7 decreases OA changes in the knee joints both in vitro and in vivo in the guinea pig OA model. OA changes were most severe in the central compartment of the medial condyle in the control group. Cartilage fibrillation and destruction, in addition to subchondral bone sclerosis and cyst formation were all less in the CMT-7 treated group compared with controls. Collagen, hyaluronan and proteoglycan content in cartilage was higher in the CMT-7 treated group compared with controls. In contrast, OA changes were not decreased in the Dox group. These results show that tetracyclines, but not all tetracyclines, can reduce the severity of OA in the guinea pig model of spontaneous OA.

New approaches for effective mutation induction in gamma field

Energy Technology Data Exchange (ETDEWEB)

Nagatomi, Shigeki [National Institute of Agrobiological Resources, Institute of Radiation Breeding, Omiya, Ibaraki (Japan)

2001-03-01

The purpose of the report is to clarify the effects of chronic irradiation using in vitro culture on inducing the mutation of two model plants. Culture technique combined with irradiation can overcome the problem of chimera formation and provided 10 times greater mutation efficiency than conventional method. Proper mutagenic treatment using cultured materials is indispensable to effective mutation induction. The chronic culture method showed the widest color spectrum in chrysanthemum and extended toward not only the negative but positive direction. However, the acute culture methods indicated a relatively low mutation rate and a very limited flower color spectrum. Flower color mutation of the regenerations could be induced more from petals and buds than from leaves. These facts is supposed that the gene loci fully expressed on floral organs may be unstable for mutation by mutagenesis or culture. It may be likely to control a direction of desired mutation. One possible reason why the chronic culture methods showed higher frequencies is that most of the cells composing the tissue and organs continually irradiated into a cell division which was highly sensitive and more mutable to irradiation. Under these conditions, many mutated sectors may accumulate in the cells of the growing organs. Regenerated mutant lines show remarkable decrease of chromosome numbers by irradiation. It is a proper indicator to monitor radiation damage. In this study, the six flower color mutant varieties registered were derived from chronic irradiation. The combined method of chronic irradiation with floral organ cultures proved to be of particularly great practical use in mutation breeding for not only flower species but any other species. (author)

Mutational analysis and clinical correlation of metastatic colorectal cancer.

Science.gov (United States)

Russo, Andrea L; Borger, Darrell R; Szymonifka, Jackie; Ryan, David P; Wo, Jennifer Y; Blaszkowsky, Lawrence S; Kwak, Eunice L; Allen, Jill N; Wadlow, Raymond C; Zhu, Andrew X; Murphy, Janet E; Faris, Jason E; Dias-Santagata, Dora; Haigis, Kevin M; Ellisen, Leif W; Iafrate, Anthony J; Hong, Theodore S

2014-05-15

Early identification of mutations may guide patients with metastatic colorectal cancer toward targeted therapies that may be life prolonging. The authors assessed tumor genotype correlations with clinical characteristics to determine whether mutational profiling can account for clinical similarities, differences, and outcomes. Under Institutional Review Board approval, 222 patients with metastatic colon adenocarcinoma (n = 158) and rectal adenocarcinoma (n = 64) who underwent clinical tumor genotyping were reviewed. Multiplexed tumor genotyping screened for >150 mutations across 15 commonly mutated cancer genes. The chi-square test was used to assess genotype frequency by tumor site and additional clinical characteristics. Cox multivariate analysis was used to assess the impact of genotype on overall survival. Broad-based tumor genotyping revealed clinical and anatomic differences that could be linked to gene mutations. NRAS mutations were associated with rectal cancer versus colon cancer (12.5% vs 0.6%; P colon cancer (13% vs 3%; P = .024) and older age (15.8% vs 4.6%; P = .006). TP53 mutations were associated with rectal cancer (30% vs 18%; P = .048), younger age (14% vs 28.7%; P = .007), and men (26.4% vs 14%; P = .03). Lung metastases were associated with PIK3CA mutations (23% vs 8.7%; P = .004). Only mutations in BRAF were independently associated with decreased overall survival (hazard ratio, 2.4; 95% confidence interval, 1.09-5.27; P = .029). The current study suggests that underlying molecular profiles can differ between colon and rectal cancers. Further investigation is warranted to assess whether the differences identified are important in determining the optimal treatment course for these patients. © 2014 American Cancer Society.

New approaches for effective mutation induction in gamma field

International Nuclear Information System (INIS)

Nagatomi, Shigeki

2001-01-01

The purpose of the report is to clarify the effects of chronic irradiation using in vitro culture on inducing the mutation of two model plants. Culture technique combined with irradiation can overcome the problem of chimera formation and provided 10 times greater mutation efficiency than conventional method. Proper mutagenic treatment using cultured materials is indispensable to effective mutation induction. The chronic culture method showed the widest color spectrum in chrysanthemum and extended toward not only the negative but positive direction. However, the acute culture methods indicated a relatively low mutation rate and a very limited flower color spectrum. Flower color mutation of the regenerations could be induced more from petals and buds than from leaves. These facts is supposed that the gene loci fully expressed on floral organs may be unstable for mutation by mutagenesis or culture. It may be likely to control a direction of desired mutation. One possible reason why the chronic culture methods showed higher frequencies is that most of the cells composing the tissue and organs continually irradiated into a cell division which was highly sensitive and more mutable to irradiation. Under these conditions, many mutated sectors may accumulate in the cells of the growing organs. Regenerated mutant lines show remarkable decrease of chromosome numbers by irradiation. It is a proper indicator to monitor radiation damage. In this study, the six flower color mutant varieties registered were derived from chronic irradiation. The combined method of chronic irradiation with floral organ cultures proved to be of particularly great practical use in mutation breeding for not only flower species but any other species. (author)

F. VON HAYEK’S THEORY OF SPONTANEOUS ORDER

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О. Nesterenko

2013-04-01

Full Text Available The essence and the genesis of spontaneous order are disclosed in the context of critical analysis of constructivism. The author’s approach to the definition of the characteristic features of the spontaneous order is proposed. The dichotomy of the order is revealed towards the economic sphere in form of spontaneous order and organization.

Spontaneous pneumomediastinum after bench press training.

Science.gov (United States)

Nishino, Tomoya

2017-04-01

Spontaneous pneumomediastinum is often associated with asthma and mainly affects adolescent males with a tall, thin body habitus. A 17-year-old man complained of chest and pharyngeal pain after bench press training and spontaneous pneumomediastinum was diagnosed. It should be considered in the differential diagnosis of chest pain of uncertain cause.

Novel Compound Heterozygous CLCNKB Gene Mutations (c.1755A>G/ c.848_850delTCT) Cause Classic Bartter Syndrome.

Science.gov (United States)

Wang, Chunli; Chen, Ying; Zheng, Bixia; Zhu, Mengshu; Fan, Jia; Wang, Juejin; Jia, Zhanjun; Huang, Songming; Zhang, Aihua

2018-02-14

Inactivated variants in CLCNKB gene encoding the basolateral chloride channel ClC-Kb cause classic Bartter syndrome characterized by hypokalemic metabolic alkalosis and hyperreninemic hyperaldosteronism. Here we identified two cBS siblings presenting hypokalemia in a Chinese family due to novel compound heterozygous CLCNKB mutations (c.848_850delTCT/c.1755A>G). Compound heterozygosity was confirmed by amplifying and sequencing the patient's genomic DNA. The synonymous mutation c.1755A>G (Thr585Thr) was located at +2bp from the 5' splice donor site in exon 15, further transcript analysis demonstrated that this single nucleotide mutation causes exclusion of exon 15 in the cDNA from the proband and his mother. Furthermore, we investigated the expression and protein trafficking change of c.848_850delTCT (TCT) and exon 15 deletion（E15）mutation in vitro. The E15 mutation markedly decreased the expression of ClC-Kb and resulted in a low-molecular-weight band (~55kD) trapping in the endoplasmic reticulum, while the TCT mutant only decreased the total and plasma membrane ClC-Kb protein expression but did not affect the subcellular localization. Finally, we studied the physiological functions of mutations by using whole-cell patch clamp and found that E15 or TCT mutation decreased the current of ClC-Kb/barttin channel. These results suggested that the compound defective mutations of CLCNKB gene are the molecular mechanism of the two cBS siblings.

Effect of Feeding an Iodine-Restricted Diet in Cats with Spontaneous Hyperthyroidism.

Science.gov (United States)

Hui, T Y; Bruyette, D S; Moore, G E; Scott-Moncrieff, J C

2015-01-01

Exclusive feeding of an iodine-restricted diet has been proposed as a method for controlling clinical manifestations of hyperthyroidism in hyperthyroid cats. To determine the effect of feeding an iodine-restricted diet on TT4 concentrations and clinical signs in cats with spontaneous hyperthyroidism. Forty-nine client-owned cats with spontaneous hyperthyroidism. Retrospective case series. Hyperthyroid cats were exclusively fed a commercially available iodine-restricted diet. Clinical response was assessed by change in weight and heart rate and serum TT4, blood urea nitrogen (BUN), and creatinine concentrations at various times during dietary management (21-60 days, 60-180 days). Serum TT4 normalized in 20/48 cats (42%) and 39/47 cats (83%) at 21-60 days and 61-180 days, respectively. Cats in which the TT4 concentrations were still above reference range at 21-60 days had a significantly higher starting TT4 than those that normalized their TT4 levels during the same time period (P = .038). Body weight did not significantly increase (P = .34) nor heart rate decrease (P = .64) during the study. There was a significant decrease in serum creatinine (P = .028). Cats in the low reference range for serum TT4 concentrations did not have a significant increase in body weight (P = .41) nor creatinine (P = .54) when compared to those with high reference range. Restricted-iodine diets were effective at maintaining serum TT4 concentrations within reference ranges for a majority of cats with spontaneous hyperthyroidism over 1 year, although not all clinical signs of hyperthyroidism improved. Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

MPL mutation profile in JAK2 mutation-negative patients with myeloproliferative disorders.

Science.gov (United States)

Ma, Wanlong; Zhang, Xi; Wang, Xiuqiang; Zhang, Zhong; Yeh, Chen-Hsiung; Uyeji, Jennifer; Albitar, Maher

2011-03-01

Mutations in the thrombopoietin receptor gene (myeloproliferative leukemia, MPL) have been reported in patients with JAK2 V617F-negative chronic myeloproliferative disorders (MPDs). We evaluated the prevalence of MPL mutations relative to JAK2 mutations in patients with suspected MPDs. A total of 2790 patient samples submitted for JAK2 mutation analysis were tested using real-time polymerase chain reaction and bidirectional sequencing of plasma RNA. JAK2 V617F-negative samples were tested for JAK2 exons 12 to 14 mutations, and those with negative results were then tested for mutations in MPL exons 10 and 11. Of the 2790 patients, 529 (18.96%) had V617F, 12 (0.43%) had small insertions or deletions in exon 12, and 7 (0.25%) had other JAK2 mutations in exons 12 to 14. Of the 2242 JAK2 mutation-negative patients, 68 (3.03%) had MPL mutations. W515L was the predominant MPL mutation (n=46; 68%), and 10 (15%) patients had other W515 variants. The remaining MPL mutations (n=12, 17%) were detected at other locations in exons 10 and 11 and included 3 insertion/deletion mutations. The S505N mutation, associated with familial MPD, was detected in 3 patients. Overall, for every 100 V617F mutations in patients with suspected MPDs, there were 12.9 MPL mutations, 2.3 JAK2 exon 12 mutations, and 1.3 JAK2 exons 13 to 14 mutations. These findings suggest that MPL mutation screening should be performed before JAK2 exons 12 to 14 testing in JAK2 V617F-negative patients with suspected MPDs.

Mitochondrial DNA deletion mutations in adult mouse cardiac side population cells

International Nuclear Information System (INIS)

Lushaj, Entela B.; Lozonschi, Lucian; Barnes, Maria; Anstadt, Emily; Kohmoto, Takushi

2012-01-01

We investigated the presence and potential role of mitochondrial DNA (mtDNA) deletion mutations in adult cardiac stem cells. Cardiac side population (SP) cells were isolated from 12-week-old mice. Standard polymerase chain reaction (PCR) was used to screen for the presence of mtDNA deletion mutations in (a) freshly isolated SP cells and (b) SP cells cultured to passage 10. When present, the abundance of mtDNA deletion mutation was analyzed in single cell colonies. The effect of different levels of deletion mutations on SP cell growth and differentiation was determined. MtDNA deletion mutations were found in both freshly isolated and cultured cells from 12-week-old mice. While there was no significant difference in the number of single cell colonies with mtDNA deletion mutations from any of the groups mentioned above, the abundance of mtDNA deletion mutations was significantly higher in the cultured cells, as determined by quantitative PCR. Within a single clonal cell population, the detectable mtDNA deletion mutations were the same in all cells and unique when compared to deletions of other colonies. We also found that cells harboring high levels of mtDNA deletion mutations (i.e. where deleted mtDNA comprised more than 60% of total mtDNA) had slower proliferation rates and decreased differentiation capacities. Screening cultured adult stem cells for mtDNA deletion mutations as a routine assessment will benefit the biomedical application of adult stem cells.

Spontaneous intracranial hypotension syndrome: magnetic resonance findings in two patients

International Nuclear Information System (INIS)

Ortega, R.; Pastor, J.; Escamilla, F.; Romero, M. I.

1999-01-01

The postural headache syndrome associated with a decrease in the cerebrospinal fluid (CSF) pressure is generally secondary to the CSF leakage that usually occurs after diagnostic lumbar puncture. Spontaneous intracranial hypotension can not be attributed to any known cause or previous diagnostic or therapeutic intervention. The syndrome is characterized by severe headache that is relieved by lying supine. During lumbar puncture, the CSF pressure is normally low. We present two patients in whom gadolinium-enhanced magnetic resonance imaging showed widespread thickening and enhancement of the dura mater and subdural fluid collections. (Author) 13 refs

Spontaneous ischaemic stroke in dogs

DEFF Research Database (Denmark)

Gredal, Hanne Birgit; Skerritt, G. C.; Gideon, P.

2013-01-01

Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms.......Translation of experimental stroke research into the clinical setting is often unsuccessful. Novel approaches are therefore desirable. As humans, pet dogs suffer from spontaneous ischaemic stroke and may hence offer new ways of studying genuine stroke injury mechanisms....

Spontaneity and international marketing performance

OpenAIRE

Souchon, Anne L.; Hughes, Paul; Farrell, Andrew M.; Nemkova, Ekaterina; Oliveira, Joao S.

2016-01-01

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link. Purpose – The purpose of this paper is to ascertain how today’s international marketers can perform better on the global scene by harnessing spontaneity. Design/methodology/approach – The authors draw on contingency theory to develop a model of the spontaneity – international marketing performance relationship, and identify three potential m...

Analysis of the Spontaneous Abortion in Chinese Married Women

Institute of Scientific and Technical Information of China (English)

高尔生; 邓新清; 何更生; 方可娟; 唐威; 楼超华

1994-01-01

The spontaneous abortion is a common type of pregnant outcomes. The spontaneous abortion rate can be used to indicate the women's fecundity and the level of the reproductive health. It is also a sensitive indicator for determing the social, economic, and health status and prenatal care. To explore the preventive method for spontaneous abortion and improve women's health level, it is important to evaluate the status of spontaneous abortion and to determine the factors affecting

An Unusual Presentation of 46,XY Pure Gonadal Dysgenesis: Spontaneous Breast Development and Menstruation.

Science.gov (United States)

Çatlı, Gönül; Alparslan, Caner; Can, P Şule; Akbay, Sinem; Kelekçi, Sefa; Atik, Tahir; Özyılmaz, Berk; Dündar, Bumin N

2015-06-01

46,XY pure gonadal dysgenesis (Swyer syndrome) is characterized by normal female genitalia at birth. It usually first becomes apparent in adolescence with delayed puberty and amenorrhea. Rarely, patients can present with spontaneous breast development and/or menstruation. A fifteen-year-old girl presented to our clinic with the complaint of primary amenorrhea. On physical examination, her external genitals were completely female. Breast development and pubic hair were compatible with Tanner stage V. Hormonal evaluation revealed a hypergonadotropic state despite a normal estrogen level. Chromosome analysis revealed a 46,XY karyotype. Pelvic ultrasonography showed small gonads and a normal sized uterus for age. SRY gene expression was confirmed by multiplex polymerase chain reaction. Direct sequencing on genomic DNA did not reveal a mutation in the SRY, SF1 and WT1 genes. After the diagnosis of Swyer syndrome was made, the patient started to have spontaneous menstrual cycles and therefore failed to attend her follow-up visits. After nine months, the patient underwent diagnostic laparoscopy. Frozen examination of multiple biopsies from gonad tissues revealed gonadoblastoma. With this report, we emphasize the importance of performing karyotype analysis, which is diagnostic for Swyer syndrome, in all cases with primary or secondary amenorrhea even in the presence of normal breast development. We also suggest that normal pubertal development in patients with Swyer syndrome may be associated with the presence of a hormonally active tumor.

Spontaneous Vesicle Recycling in the Synaptic Bouton

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Sven eTruckenbrodt

2014-12-01

Full Text Available The trigger for synaptic vesicle exocytosis is Ca2+, which enters the synaptic bouton following action potential stimulation. However, spontaneous release of neurotransmitter also occurs in the absence of stimulation in virtually all synaptic boutons. It has long been thought that this represents exocytosis driven by fluctuations in local Ca2+ levels. The vesicles responding to these fluctuations are thought to be the same ones that release upon stimulation, albeit potentially triggered by different Ca2+ sensors. This view has been challenged by several recent works, which have suggested that spontaneous release is driven by a separate pool of synaptic vesicles. Numerous articles appeared during the last few years in support of each of these hypotheses, and it has been challenging to bring them into accord. We speculate here on the origins of this controversy, and propose a solution that is related to developmental effects. Constitutive membrane traffic, needed for the biogenesis of vesicles and synapses, is responsible for high levels of spontaneous membrane fusion in young neurons, probably independent of Ca2+. The vesicles releasing spontaneously in such neurons are not related to other synaptic vesicle pools and may represent constitutively releasing vesicles (CRVs rather than bona fide synaptic vesicles. In mature neurons, constitutive traffic is much dampened, and the few remaining spontaneous release events probably represent bona fide spontaneously releasing synaptic vesicles (SRSVs responding to Ca2+ fluctuations, along with a handful of CRVs that participate in synaptic vesicle turnover.

Spontaneous Atraumatic Mediastinal Hemorrhage

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