Increased sensitivity to salt stress in tocopherol-deficient Arabidopsis mutants growing in a hydroponic system

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Ellouzi, Hasna; Hamed, Karim Ben; Cela, Jana; Müller, Maren; Abdelly, Chedly; Munné-Bosch, Sergi

2013-01-01

Recent studies suggest that tocopherols could play physiological roles in salt tolerance but the mechanisms are still unknown. In this study, we analyzed changes in growth, mineral and oxidative status in vte1 and vte4 Arabidopsis thaliana mutants exposed to salt stress. vte1 and vte4 mutants lack α-tocopherol, but only the vte1 mutant is additionally deficient in γ-tocopherol. Results showed that a deficiency in vitamin E leads to reduced growth and increased oxidative stress in hydroponically-grown plants. This effect was observed at early stages, not only in rosettes but also in roots. The vte1 mutant was more sensitive to salt-induced oxidative stress than the wild type and the vte4 mutant. Salt sensitivity was associated with (i) high contents of Na+, (ii) reduced efficiency of PSII photochemistry (Fv/Fm ratio) and (iii) more pronounced oxidative stress as indicated by increased hydrogen peroxide and malondialdeyde levels. The vte 4 mutant, which accumulates γ- instead of α-tocopherol showed an intermediate sensitivity to salt stress between the wild type and the vte1 mutant. Contents of abscisic acid, jasmonic acid and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid were higher in the vte1 mutant than the vte4 mutant and wild type. It is concluded that vitamin E-deficient plants show an increased sensitivity to salt stress both in rosettes and roots, therefore indicating the positive role of tocopherols in stress tolerance, not only by minimizing oxidative stress, but also controlling Na+/K+ homeostasis and hormonal balance. PMID:23299430

Induction of Aspergillus oryzae mutant strains producing increased levels of α-amylase by gamma-irradiation

International Nuclear Information System (INIS)

Ito, Hitoshi; Nessa, Azizun

1996-01-01

Spores of Aspergillus oryzae IAM 2630 were suspended in 0.067 m phosphate buffer and irradiated with gamma rays. Spores were incubated for 7 days and colony mutants counted by observing colour change compared to normal colours. α-amylase activities of the normal and mutant colonies were assayed. DNA assay of the spores was also carried out, after culture on different plating media. Enzyme production increased 2-5 times with increasing radiation dose. Increased spore size and DNA content was also observed in mutant strains with higher enzyme production suggesting that enzyme production is genetically controlled. Ultraviolet radiation did not appear to induce higher frequency of mutation. (UK)

Induction of Aspergillus oryzae mutant strains producing increased levels of {alpha}-amylase by gamma-irradiation

Energy Technology Data Exchange (ETDEWEB)

Ito, Hitoshi; Nessa, Azizun [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment

1996-12-01

Spores of Aspergillus oryzae IAM 2630 were suspended in 0.067 m phosphate buffer and irradiated with gamma rays. Spores were incubated for 7 days and colony mutants counted by observing colour change compared to normal colours. {alpha}-amylase activities of the normal and mutant colonies were assayed. DNA assay of the spores was also carried out, after culture on different plating media. Enzyme production increased 2-5 times with increasing radiation dose. Increased spore size and DNA content was also observed in mutant strains with higher enzyme production suggesting that enzyme production is genetically controlled. Ultraviolet radiation did not appear to induce higher frequency of mutation. (UK).

Increased riboflavin production from activated bleaching earth by a mutant strain of Ashbya gossypii.

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Tajima, Satoshi; Itoh, Yoko; Sugimoto, Takashi; Kato, Tatsuya; Park, Enoch Y

2009-10-01

The production of riboflavin from vegetable oil was increased using a mutant strain of Ashbya gossypii. This mutant was generated by treating the wild-type strain with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Riboflavin production was 10-fold higher in the mutant compared to the wild-type strain. The specific intracellular catalase activity after 3 d of culture was 6-fold higher in the mutant than in the wild-type strain. For the mutant, riboflavin production in the presence of 40 mM hydrogen peroxide was 16% less than that in the absence of hydrogen peroxide, whereas it was 56% less for the wild-type strain. The isocitrate lyase (ICL) activity of the mutant was 0.26 mU/mg of protein during the active riboflavin production phase, which was 2.6-fold higher than the wild-type strain. These data indicate that the mutant utilizes the carbon flux from the TCA cycle to the glyoxylate cycle more efficiently than the wild-type strain, resulting in enhanced riboflavin production. This novel mutant has the potential to be of use for industrial-scale riboflavin production from waste-activated bleaching earth (ABE), thereby transforming a useless material into a valuable bioproduct.

Increased Protein Stability and Decreased Protein Turnover in the Caenorhabditis elegans Ins/IGF-1 daf-2 Mutant.

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Depuydt, Geert; Shanmugam, Nilesh; Rasulova, Madina; Dhondt, Ineke; Braeckman, Bart P

2016-12-01

In Caenorhabditis elegans, cellular proteostasis is likely essential for longevity. Autophagy has been shown to be essential for lifespan extension of daf-2 insulin/IGF mutants. Therefore, it can be hypothesized that daf-2 mutants achieve this phenotype by increasing protein turnover. However, such a mechanism would exert a substantial energy cost. By using classical 35 S pulse-chase labeling, we observed that protein synthesis and degradation rates are decreased in young adults of the daf-2 insulin/IGF mutants. Although reduction of protein turnover may be energetically favorable, it may lead to accumulation and aggregation of damaged proteins. As this has been shown not to be the case in daf-2 mutants, another mechanism must exist to maintain proteostasis in this strain. We observed that proteins isolated from daf-2 mutants are more soluble in acidic conditions due to increased levels of trehalose. This suggests that trehalose may decrease the potential for protein aggregation and increases proteostasis in the daf-2 mutants. We postulate that daf-2 mutants save energy by decreasing protein turnover rates and instead stabilize their proteome by trehalose. © The Author 2016. Published by Oxford University Press on behalf of The Gerontological Society of America.

Ultraviolet light-induced mutants of Streptococcus lactis subspecies diacetylactis with enhanced acid- or flavor-producing abilities

International Nuclear Information System (INIS)

Kuila, R.K.; Ranganathan, B.

1978-01-01

A strain of Streptococcus lactis subspecies diacetylactis S 1 isolated from fresh milk was exposed to 7200 ergs/mm 2 of ultraviolet radiation. Over 8100 colonies surviving from 7.4 x 10 6 cells exposed to radiation were screened on citrate agar for detection and isolation of mutants with increased flavor and/or acid production. Of the survivors, 960 were type-I mutants that exhibited clear zone on citrate agar after 18 h (presumed to be high diacetyl producers), and 288 were type-II mutants which did not exhibit clear zones on citrate agar for up to 72 h (high acid producers). Type-II mutants produced an average .93 percent titratable acidity which was 34 percent more than the .69 percent of the parent. Reduction in titratable acidity (56 percent less) was considerable in type-I mutants, compared with the parent culture. Diacetyl + acetoin production by type-I mutants was 137.9 ppM which has 4.5 times more than that of the parental strain. Acetaldehyde production in the mutants varied from 1.5 to 34.5 ppM (parent culture 3.0 ppM). The mutants with increased acid and high acetoin plus diacetyl production were stable after 50 subcultures in milk

Production of mutants of Candida utilis with increased resistence against furfural

International Nuclear Information System (INIS)

Stehlik, G.; Baron, M.; Turanitz, K.; Schneider, F.

1978-01-01

By repeated γ-irradiation treatments and following selections a mutant of Candida utilis weissenbachii was isolated showing increased resistance against furfural as compared to its wild type. Growing and radiation survival behavior of these yeasts are compared. Analysis of furfural was done by gaschromatography on Porapak Q. (author)

Mildew resistant and less lodging wheat mutants induced in Iran

International Nuclear Information System (INIS)

Naghedi-Ahmadi, I.

1989-01-01

''Tabassi'' is a lodging and mildew susceptible cultivar. To induce mutations, seeds were gamma irradiated (50 to 150 Gy) in 1982 and selection for lodging resistance was carried out in M 2 . During field experiments with the mutant lines in 1985/86 there has been a heavy mildew epidemic under which mutant 63-5-I (derived from 50 Gy treatment) exhibited considerable resistance and as a consequence, higher yield. The control was 100% infected, the mutant only 40%. The mutant yielded 31% more grain, 7.5% less straw and 4.5% more protein than the control. Lodging of 63-5-I was only 60% in an experiment under rainfed conditions in the same season, resulting in a relative yield increase of about 11%. In 1986/87 there was no mildew epidemic and the mutant yielded the same as ''Tabassi''

Conserved role of unc-79 in ethanol responses in lightweight mutant mice.

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David J Speca

2010-08-01

Full Text Available The mechanisms by which ethanol and inhaled anesthetics influence the nervous system are poorly understood. Here we describe the positional cloning and characterization of a new mouse mutation isolated in an N-ethyl-N-nitrosourea (ENU forward mutagenesis screen for animals with enhanced locomotor activity. This allele, Lightweight (Lwt, disrupts the homolog of the Caenorhabditis elegans (C. elegans unc-79 gene. While Lwt/Lwt homozygotes are perinatal lethal, Lightweight heterozygotes are dramatically hypersensitive to acute ethanol exposure. Experiments in C. elegans demonstrate a conserved hypersensitivity to ethanol in unc-79 mutants and extend this observation to the related unc-80 mutant and nca-1;nca-2 double mutants. Lightweight heterozygotes also exhibit an altered response to the anesthetic isoflurane, reminiscent of unc-79 invertebrate mutant phenotypes. Consistent with our initial mapping results, Lightweight heterozygotes are mildly hyperactive when exposed to a novel environment and are smaller than wild-type animals. In addition, Lightweight heterozygotes exhibit increased food consumption yet have a leaner body composition. Interestingly, Lightweight heterozygotes voluntarily consume more ethanol than wild-type littermates. The acute hypersensitivity to and increased voluntary consumption of ethanol observed in Lightweight heterozygous mice in combination with the observed hypersensitivity to ethanol in C. elegans unc-79, unc-80, and nca-1;nca-2 double mutants suggests a novel conserved pathway that might influence alcohol-related behaviors in humans.

Sterile mutant of Verbena hybrida induced by heavy ion beam irradiation and wild species V. peruviana exhibit self-incompatible phenotype

International Nuclear Information System (INIS)

Saito, H.; Hayashi, Y.; Abe, T.; Kanaya, T.; Suzuki, K.

2005-01-01

Full text: Garden verbenas (Verbena hybrida) belonging to the Verbenaceae family are originated from interspecific hybridization among several species, many cultivars frequently produce seeds. Recently, a sterile mutant has been isolated in the verbena cultivar 'Coral Pink' of Temari series (Suntory Flowers Ltd., Tokyo, Japan) by mutation induction using heavy-ion beams at RIKEN Accelarator Research Facility (RARF, Saitama, Japan). We investigated pollen and ovule fertility assessed by acetocarmin staining, seed-set following controlled-pollination tests and behavior of pollen tubes in pistils with the sterile mutant of 'Coral Pink' (SC) and its original fertile one (FC). As the results, although SC has functional male and female gametes, few self-pollinated flowers carry out seed-set, leading to sterile phenotype. Additionally, the sterile mechanism of SC was compared with the wild species V. peruviana (VP) which is one of origin of Temari series and exhibits sterility. Interestingly, similar phenotype was observed in PV. We further investigated, therefore, whether there are differences on self-incompatible reaction between SC and VP. (author)

Sterile mutant of Verbena hybrida induced by heavy ion beam irradiation and wild species V. peruviana exhibit self-incompatible phenotype

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Saito, H; Hayashi, Y; Abe, T [RIKEN, Wako (Japan); Kanaya, T; Suzuki, K [Suntory Flowers Ltd., Higashiomi (Japan)

2005-07-01

Full text: Garden verbenas (Verbena hybrida) belonging to the Verbenaceae family are originated from interspecific hybridization among several species, many cultivars frequently produce seeds. Recently, a sterile mutant has been isolated in the verbena cultivar 'Coral Pink' of Temari series (Suntory Flowers Ltd., Tokyo, Japan) by mutation induction using heavy-ion beams at RIKEN Accelarator Research Facility (RARF, Saitama, Japan). We investigated pollen and ovule fertility assessed by acetocarmin staining, seed-set following controlled-pollination tests and behavior of pollen tubes in pistils with the sterile mutant of 'Coral Pink' (SC) and its original fertile one (FC). As the results, although SC has functional male and female gametes, few self-pollinated flowers carry out seed-set, leading to sterile phenotype. Additionally, the sterile mechanism of SC was compared with the wild species V. peruviana (VP) which is one of origin of Temari series and exhibits sterility. Interestingly, similar phenotype was observed in PV. We further investigated, therefore, whether there are differences on self-incompatible reaction between SC and VP. (author)

Characterization of a JAZ7 activation-tagged Arabidopsis mutant with increased susceptibility to the fungal pathogen Fusarium oxysporum

Science.gov (United States)

Thatcher, Louise F.; Cevik, Volkan; Grant, Murray; Zhai, Bing; Jones, Jonathan D.G.; Manners, John M.; Kazan, Kemal

2016-01-01

In Arabidopsis, jasmonate (JA)-signaling plays a key role in mediating Fusarium oxysporum disease outcome. However, the roles of JASMONATE ZIM-domain (JAZ) proteins that repress JA-signaling have not been characterized in host resistance or susceptibility to this pathogen. Here, we found most JAZ genes are induced following F. oxysporum challenge, and screening T-DNA insertion lines in Arabidopsis JAZ family members identified a highly disease-susceptible JAZ7 mutant (jaz7-1D). This mutant exhibited constitutive JAZ7 expression and conferred increased JA-sensitivity, suggesting activation of JA-signaling. Unlike jaz7 loss-of-function alleles, jaz7-1D also had enhanced JA-responsive gene expression, altered development and increased susceptibility to the bacterial pathogen Pst DC3000 that also disrupts host JA-responses. We also demonstrate that JAZ7 interacts with transcription factors functioning as activators (MYC3, MYC4) or repressors (JAM1) of JA-signaling and contains a functional EAR repressor motif mediating transcriptional repression via the co-repressor TOPLESS (TPL). We propose through direct TPL recruitment, in wild-type plants JAZ7 functions as a repressor within the JA-response network and that in jaz7-1D plants, misregulated ectopic JAZ7 expression hyper-activates JA-signaling in part by disturbing finely-tuned COI1-JAZ-TPL-TF complexes. PMID:26896849

Selection of high hectolitre weight mutants of winter wheat

International Nuclear Information System (INIS)

Crowley, C.; Jones, P.

1989-01-01

Grain quality in wheat includes hectolitre weight (HLW) besides protein content and thousand-grain weight (TGW). The British winter wheat variety ''Guardian'' has a very high yield potential. Although the long grain of ''Guardian'' results in a desirable high TGW the HLW is too low. To select mutants exhibiting increased HLW the character was first analyzed to identify traits that could more easily be screened for using M 2 seeds. In comparison of 6 wheat cultivars, correlation analyses with HLW resulted in coefficients of -0.86 (grain length, L:P 2 seeds for shorter, less prolate grains. Mutagenesis was carried out using EMS sulphonate (1.8 or 3.6%), sodium azide (2 or 20 mM) or X-rays (7.5 or 20 kR). 69 M 2 grains with altered shape were selected. Examination of the M 3 progeny confirmed 6 grain-shape mutants, most of them resulting from EMS treatment (Table). Two of the mutants showed TGW values significantly below the parental variety, but three mutants exhibited HLW and TGW values significantly greater than those of the parental variety. Microplot yield trails on selected M 3 lines are in progress. The influence of physical grain characteristics on HLW offers prospects for mechanical fractionation of large M 2 populations. The application of gravity separators (fractionation on the basis of grain density) and sieves (fractionation on the basis of grain length) in screening mutants possessing improved grain quality is being investigated

Molecular Genetic Identification Of Some Flax Mutants

International Nuclear Information System (INIS)

AMER, I.M.; MOUSTAFA, H.A.M.

2009-01-01

Five flax genotypes (Linum usitatissimum L.) i.e., commercial cultivar Sakha 2, the mother variety Giza 4 and three mutant types induced by gamma rays, were screened for their salinity tolerance in field experiments (salinity concentration was 8600 and 8300 ppm for soil and irrigation water, respectively). Mutation 6 was the most salt tolerant as compared to the other four genotypes.RAPD technique was used to detect some molecular markers associated with salt tolerance in flax (Mut 6), RAPD-PCR results using 12 random primers exhibited 149 amplified fragments; 91.9% of them were polymorphic and twelve molecular markers (8.1%) for salt tolerant (mutant 6) were identified with molecular size ranged from 191 to 4159 bp and only eight primers successes to amplify these specific markers. Concerning the other mutants, Mut 15 and Mut 25 exhibited 4.3% and 16.2% specific markers, respectively. The induced mutants exhibited genetic similarity to the parent variety were about 51%, 58.3% and 61.1% for Mut 25, Mut 6 and Mut 15, respectively. These specific markers (SM) are used for identification of the induced mutations and it is important for new variety registration.

mei-9/sup a/ mutant of Drosophila melanogaster increases mutagen sensitivity and decreases excision repair

International Nuclear Information System (INIS)

Boyd, J.B.; Golino, M.D.; Setlow, R.B.

1976-01-01

The mei-9/sup a/ mutant of Drosophila melanogaster, which reduces meiotic recombination in females, is deficient in the excision of uv-induced pyrimidine dimers in both sexes. Assays were performed in primary cultures and established cell lines derived from embryos. An endonuclease preparation from M. luteus, which is specific for pyrimidine dimers, was employed to monitor uv-induced dimers in cellular DNA. The rate of disappearance of endonuclease-sensitive sites from DNA of control cells is 10-20 times faster than that from mei-9/sup a/ cells. The mutant mei-218, which is also deficient in meiotic recombination, removes nuclease-sensitive sites at control rates. The mei-9/sup a/ cells exhibit control levels of photorepair, postreplication repair and repair of single strand breaks. In mei-9 cells DNA synthesis and possibly postreplication repair are weakly sensitive to caffeine. Larvae which are hemizygous for either of the two mutants that define the mei-9 locus are hypersensitive to killing by the mutagens methyl methanesulfonate, nitrogen mustard and 2-acetylaminofluorene. Larvae hemizygous for the mei-218 mutant are insensitive to each of these reagents. These data demonstrate that the mei-9 locus is active in DNA repair of somatic cells. Thus functions involved in meiotic recombination are also active in DNA repair in this higher eukaryote. The results are consistent with the earlier suggestions that the mei-9 locus functions in the exchange events of meiosis. The mei-218 mutation behaves differently in genetic tests and our data suggest its function may be restricted to meiosis. These studies demonstrate that currently recognized modes of DNA repair can be efficiently detected in primary cell cultures derived from Drosophila embryos

Production and characterization of radiation-sensitive meiotic mutants of Coprinus cinereus

International Nuclear Information System (INIS)

Zolan, M.E.; Tremel, C.J.; Pukkila, P.J.

1988-01-01

We have isolated four gamma-sensitive mutants of the basidiomycete Coprinus cinereus. When homozygous, two of these (rad 3-1 and rad 9-1) produce fruiting bodies with very few viable basidiospores, the products of meiosis in this organism. A less radiation-sensitive allele of RAD 3, rad 3-2, causes no apparent meiotic defect in homozygous strains. Quantitative measurements of oidial survival of rad 3-1;rad 9-1 double mutants compared to the single mutants indicated that rad 3-1 and rad 9-1 mutants are defective in the same DNA repair pathway. In the pew viable basidiospores that are produced by these two strains, essentially normal levels of meiotic recombination can be detected. None of the mutants exhibits increased sensitivity to UV radiation. Cytological examination of meiotic chromosomes from mutant and wild-type fruiting bodies showed that rad 3-1 homozygous strains fail to condense and pair homologous chromosomes during prophase I. Although rad 9-1 strains are successful at chromosome pairing, meiosis is usually not completed in these mutants

Analysis of triclosan-selected Salmonella enterica mutants of eight serovars revealed increased aminoglycoside susceptibility and reduced growth rates.

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Ulrike Rensch

Full Text Available The biocide triclosan (TRC is used in a wide range of household, personal care, veterinary, industrial and medical products to control microbial growth. This extended use raises concerns about a possible association between the application of triclosan and the development of antibiotic resistance. In the present study we determined triclosan mutant prevention concentrations (MPC for Salmonella enterica isolates of eight serovars and investigated selected mutants for their mechanisms mediating decreased susceptibility to triclosan. MPCTRC values were 8-64-fold higher than MIC values and ranged between 1-16 µg/ml. The frequencies at which mutants were selected varied between 1.3 x 10(-10-9.9 x 10(-11. Even if MIC values of mutants decreased by 3-7 dilution steps in the presence of the efflux pump inhibitor Phe-Arg-β-naphtylamide, only minor changes were observed in the expression of genes encoding efflux components or regulators, indicating that neither the major multidrug efflux pump AcrAB-TolC nor AcrEF are up-regulated in triclosan-selected mutants. Nucleotide sequence comparisons confirmed the absence of alterations in the regulatory regions acrRA, soxRS, marORAB, acrSE and ramRA of selected mutants. Single bp and deduced Gly93→Val amino acid exchanges were present in fabI, the target gene of triclosan, starting from a concentration of 1 µg/ml TRC used for MPC determinations. The fabI genes were up to 12.4-fold up-regulated. Complementation experiments confirmed the contribution of Gly93→Val exchanges and fabI overexpression to decreased triclosan susceptibility. MIC values of mutants compared to parent strains were even equal or resulted in a more susceptible phenotype (1-2 dilution steps for the aminoglycoside antibiotics kanamycin and gentamicin as well as for the biocide chlorhexidine. Growth rates of selected mutants were significantly lower and hence, might partly explain the rare occurrence of Salmonella field isolates exhibiting

Mutant fatty acid desaturase and methods for directed mutagenesis

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Shanklin, John [Shoreham, NY; Whittle, Edward J [Greenport, NY

2008-01-29

The present invention relates to methods for producing fatty acid desaturase mutants having a substantially increased activity towards substrates with fewer than 18 carbon atom chains relative to an unmutagenized precursor desaturase having an 18 carbon chain length specificity, the sequences encoding the desaturases and to the desaturases that are produced by the methods. The present invention further relates to a method for altering a function of a protein, including a fatty acid desaturase, through directed mutagenesis involving identifying candidate amino acid residues, producing a library of mutants of the protein by simultaneously randomizing all amino acid candidates, and selecting for mutants which exhibit the desired alteration of function. Candidate amino acids are identified by a combination of methods. Enzymatic, binding, structural and other functions of proteins can be altered by the method.

Serrated leaf mutant in mungbean (Vigna radiata (L) Wilczek)

International Nuclear Information System (INIS)

Malik, I.A.; Ghulam, Sarwar; Yousaf, Ali; Saleem, M.

1988-01-01

Dry dormant seeds of mungbean (Vigna radiata (L) Wilczek) were treated with gamma rays (15, 30 and 60 kR). The serrated leaf mutation was noticed in M 2 of cultivar Pak 32 treated with 60 kR. Cf 14 plants, 3 showed the altered leaf structure and the others were normal. The feature of this mutant was the deep serration of leaflet margins. The mutant had large thick leaflets with prominent venation. The mutant bred true in the M 3 and successive generation. Details of the morphological characteristics of the mutant are presented. The mutant exhibited slower growth particularly during the early stages of development, flowered later and attained shorter height. There was an increase in the number of pods, in seed weight and in seed protein content, but number of seed per pod was considerably reduced. The seed coat colour showed a change from green to yellowish green. In the mutant's flowers the stamina were placed much below the stigma level and the stigma sometimes protruded the corolla. Outcrossing of 4% recorded in some of the mutant lines revealed a reduced cleistogamy. The low number of seeds per pod in the mutant could be due to reduced pollen fertility. The mutant behaved as monogenic recessive. The symbols SL/sl are proposed for this allelic pair. The mutant may have use as a green manure crop because of its large foliage and for the breeders as a genetic marker

Isolation and characterization of X-linked mutants of Drosophila melanogaster which are sensitive to mutagens

International Nuclear Information System (INIS)

Boyd, J.B.; Golino, M.D.; Nguyen, T.D.; Green, M.M.

1976-01-01

Thirteen X-linked mutants have been isolated in Drosophila melanogaster which render male and homozygous female larvae sensitive to the mutagen methyl methanesulfonate. Their characterization and preliminary assignment to functional groups is described. Four of these mutants are alleles of mei-41. Like previously isolated alleles of this locus, these mutants reduce fertility and increase loss and nondisjunction of the X-chromosome in homozygous females. The remaining mutants have been tentatively assigned to six functional groups (two mutants to the mus(1)101 locus, two to mus(1)102, two to mus(1)103, and one each to mus(1)104, mus(1)105, and mus(1)106. Several of the complementation groups can be distinguished on the basis of nondisjunction and cross sensitivity to mutagens. Females homozygous for the mei-41, mus(1)101 and mus(1)102 mutants exhibit elevated levels of nondisjunction. Mutants belonging to complementation groups mei-41, mus(1)101, and mus(1)104 are sensitive to nitrogen mustard (HN2) in addition to their MMS sensitivity. Among these mutants there is currently a direct correlation between sensitivity to HN2, sensitivity to 2-acetylaminofluorene and a deficiency in post-replication repair. Only the mei-41 mutants are hypersensitive to uv radiation, although several of the mutants exhibit sensitivity to γ-rays. Semidominance is observed in female larvae of the mei-41, mus(1)104, and mus(1)103 mutants after exposure to high concentrations of MMS. The properties of the mutants generally conform to a pattern which has been established for related mutants in yeast

Mutant heterosis in rice

International Nuclear Information System (INIS)

1987-01-01

In the variety TKM6 a high yielding semidwarf mutant has been induced. This TKM6 mutant was used in test crosses with a number of other varieties and mutants to examine the extent of heterosis of dwarfs in rice and to select superior crosses. An excerpt of the published data is given. It appears from the backcross of the mutant with its original variety, that an increase in number of productive tillers occurs in the hybrid, leading to a striking grain yield increase, while the semi-dwarf culm length (the main mutant character) reverts to the normal phenotype. In the cross with IR8 on the other hand, there is only a minimal increase in tiller number but a substantial increase in TGW leading to more than 30% yield increase over the better parent

A novel mouse Fgfr2 mutant, hobbyhorse (hob, exhibits complete XY gonadal sex reversal.

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Pam Siggers

Full Text Available The secreted molecule fibroblast growth factor 9 (FGF9 plays a critical role in testis determination in the mouse. In embryonic gonadal somatic cells it is required for maintenance of SOX9 expression, a key determinant of Sertoli cell fate. Conditional gene targeting studies have identified FGFR2 as the main gonadal receptor for FGF9 during sex determination. However, such studies can be complicated by inefficient and variable deletion of floxed alleles, depending on the choice of Cre deleter strain. Here, we report a novel, constitutive allele of Fgfr2, hobbyhorse (hob, which was identified in an ENU-based forward genetic screen for novel testis-determining loci. Fgr2hob is caused by a C to T mutation in the invariant exon 7, resulting in a polypeptide with a mis-sense mutation at position 263 (Pro263Ser in the third extracellular immunoglobulin-like domain of FGFR2. Mutant homozygous embryos show severe limb and lung defects and, when on the sensitised C57BL/6J (B6 genetic background, undergo complete XY gonadal sex reversal associated with failure to maintain expression of Sox9. Genetic crosses employing a null mutant of Fgfr2 suggest that Fgr2hob is a hypomorphic allele, affecting both the FGFR2b and FGFR2c splice isoforms of the receptor. We exploited the consistent phenotype of this constitutive mutant by analysing MAPK signalling at the sex-determining stage of gonad development, but no significant abnormalities in mutant embryos were detected.

Drosophila mutants of the autism candidate gene neurobeachin (rugose) exhibit neuro-developmental disorders, aberrant synaptic properties, altered locomotion, and impaired adult social behavior and activity patterns.

Science.gov (United States)

Wise, Alexandria; Tenezaca, Luis; Fernandez, Robert W; Schatoff, Emma; Flores, Julian; Ueda, Atsushi; Zhong, Xiaotian; Wu, Chun-Fang; Simon, Anne F; Venkatesh, Tadmiri

2015-01-01

Autism spectrum disorder (ASD) is a neurodevelopmental disorder in humans characterized by complex behavioral deficits, including intellectual disability, impaired social interactions, and hyperactivity. ASD exhibits a strong genetic component with underlying multigene interactions. Candidate gene studies have shown that the neurobeachin (NBEA) gene is disrupted in human patients with idiopathic autism ( Castermans et al., 2003 ). The NBEA gene spans the common fragile site FRA 13A and encodes a signal scaffold protein ( Savelyeva et al., 2006 ). In mice, NBEA has been shown to be involved in the trafficking and function of a specific subset of synaptic vesicles. ( Medrihan et al., 2009 ; Savelyeva et al., 2006 ). Rugose (rg) is the Drosophila homolog of the mammalian and human NBEA. Our previous genetic and molecular analyses have shown that rg encodes an A kinase anchor protein (DAKAP 550), which interacts with components of the epidermal growth factor receptor or EGFR and Notch-mediated signaling pathways, facilitating cross talk between these and other pathways ( Shamloula et al., 2002 ). We now present functional data from studies on the larval neuromuscular junction that reveal abnormal synaptic architecture and physiology. In addition, adult rg loss-of-function mutants exhibit defective social interactions, impaired habituation, aberrant locomotion, and hyperactivity. These results demonstrate that Drosophila NBEA (rg) mutants exhibit phenotypic characteristics reminiscent of human ASD and thus could serve as a genetic model for studying ASDs.

Tumor suppressor PTEN affects tau phosphorylation: deficiency in the phosphatase activity of PTEN increases aggregation of an FTDP-17 mutant Tau

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Zhang Xue

2006-07-01

Full Text Available Abstract Background Aberrant hyperphosphorylation of tau protein has been implicated in a variety of neurodegenerative disorders. Although a number of protein kinases have been shown to phosphorylate tau in vitro and in vivo, the molecular mechanisms by which tau phosphorylation is regulated pathophysiologically are largely unknown. Recently, a growing body of evidence suggests a link between tau phosphorylation and PI3K signaling. In this study, phosphorylation, aggregation and binding to the microtubule of a mutant frontal temporal dementia and parkinsonism linked to chromosome 17 (FTDP-17 tau in the presence of tumor suppressor PTEN, a major regulatory component in PI3K signaling, were investigated. Results Phosphorylation of the human mutant FTDP-17 tau, T40RW, was evaluated using different phospho-tau specific antibodies in the presence of human wild-type or phosphatase activity null mutant PTEN. Among the evaluated phosphorylation sites, the levels of Ser214 and Thr212 phospho-tau proteins were significantly decreased in the presence of wild-type PTEN, and significantly increased when the phosphatase activity null mutant PTEN was ectopically expressed. Fractionation of the mutant tau transfected cells revealed a significantly increased level of soluble tau in cytosol when wild-type PTEN was expressed, and an elevated level of SDS-soluble tau aggregates in the presence of the mutant PTEN. In addition, the filter/trap assays detected more SDS-insoluble mutant tau aggregates in the cells overexpressing the mutant PTEN compared to those in the cells overexpressing wild-type PTEN and control DNA. This notion was confirmed by the immunocytochemical experiment which demonstrated that the overexpression of the phosphatase activity null mutant PTEN caused the mutant tau to form aggregates in the COS-7 cells. Conclusion Tumor suppressor PTEN can alleviate the phosporylation of the mutant FTDP-17 tau at specific sites, and the phosphatase activity

Heterozygous inactivation of tsc2 enhances tumorigenesis in p53 mutant zebrafish

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Seok-Hyung Kim

2013-07-01

Tuberous sclerosis complex (TSC is a multi-organ disorder caused by mutations of the TSC1 or TSC2 genes. A key function of these genes is to inhibit mTORC1 (mechanistic target of rapamycin complex 1 kinase signaling. Cells deficient for TSC1 or TSC2 have increased mTORC1 signaling and give rise to benign tumors, although, as a rule, true malignancies are rarely seen. In contrast, other disorders with increased mTOR signaling typically have overt malignancies. A better understanding of genetic mechanisms that govern the transformation of benign cells to malignant ones is crucial to understand cancer pathogenesis. We generated a zebrafish model of TSC and cancer progression by placing a heterozygous mutation of the tsc2 gene in a p53 mutant background. Unlike tsc2 heterozygous mutant zebrafish, which never exhibited cancers, compound tsc2;p53 mutants had malignant tumors in multiple organs. Tumorigenesis was enhanced compared with p53 mutant zebrafish. p53 mutants also had increased mTORC1 signaling that was further enhanced in tsc2;p53 compound mutants. We found increased expression of Hif1-α, Hif2-α and Vegf-c in tsc2;p53 compound mutant zebrafish compared with p53 mutant zebrafish. Expression of these proteins probably underlies the increased angiogenesis seen in compound mutant zebrafish compared with p53 mutants and might further drive cancer progression. Treatment of p53 and compound mutant zebrafish with the mTORC1 inhibitor rapamycin caused rapid shrinkage of tumor size and decreased caliber of tumor-associated blood vessels. This is the first report using an animal model to show interactions between tsc2, mTORC1 and p53 during tumorigenesis. These results might explain why individuals with TSC rarely have malignant tumors, but also suggest that cancer arising in individuals without TSC might be influenced by the status of TSC1 and/or TSC2 mutations and be potentially treatable with mTORC1 inhibitors.

Arabidopsis AtDjA3 null mutant shows increased sensitivity to abscisic acid, salt, and osmotic stress in germination and postgermination stages

Directory of Open Access Journals (Sweden)

Silvia eSalas-Muñoz

2016-02-01

Full Text Available DnaJ proteins are essential co-chaperones involved in abiotic and biotic stress responses. Arabidopsis AtDjA3 gene encodes a molecular co-chaperone of 420 amino acids, which belongs to the J-protein family. In this study, we report the functional characterization of the AtDjA3 gene using the Arabidopsis knockout line designated j3 and the 35S::AtDjA3 overexpression lines. Loss of AtDjA3 function was associated with small seed production. In fact, j3 mutant seeds showed a reduction of 24% in seed weight compared to Col-0 seeds. Expression analysis showed that the AtDjA3 gene was modulated in response to NaCl, glucose, and abscisic acid. The j3 line had increased sensitivity to NaCl and glucose treatments in the germination and cotyledon development in comparison to parental Col-0. Furthermore, the j3 mutant line exhibited higher abscisic acid sensitivity in comparison to parental Col-0 and 35S::AtDjA3 overexpression lines. In addition, we examined the expression of ABI3 gene, which is a central regulator in ABA signalling, in j3 mutant and 35S::AtDjA3 overexpression lines. Under 5 μM ABA treatment at 24 h, j3 mutant seedlings displayed higher ABI3 expression, whereas in 35S::AtDjA3 overexpression lines, ABI3 gene expression was repressed. Taken together, these results demonstrate that the AtDjA3 gene is involved in seed development and abiotic stress tolerance.

Defective Glycinergic Synaptic Transmission in Zebrafish Motility Mutants

OpenAIRE

Hirata, Hiromi; Carta, Eloisa; Yamanaka, Iori; Harvey, Robert J.; Kuwada, John Y.

2010-01-01

Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo) mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR) β subunit genes. These mutants exhibit a loss of glycinergic synaptic ...

Photosynthetic Characteristics of Flag Leaves in Rice White Stripe Mutant 6001 During Senescence Process

Directory of Open Access Journals (Sweden)

Xiao-hui ZHEN

2014-11-01

Full Text Available Physiological, biochemical and electron microscopy analyses were used to investigate the photosynthetic performance of flag leaves in rice white stripe mutant 6001 during the senescence process. Results showed that the chlorophyll content at the heading and milk-ripe stages in rice mutant 6001 were about 34.78% and 3.00% less than those in wild type 6028, respectively. However, the chlorophyll content at the fully-ripe stage in rice mutant 6001 was higher than that in wild type 6028. At the heading stage, the net photosynthetic rate (Pn in rice mutant 6001 was lower than that in wild type 6028. Rice mutant 6001 also exhibited a significantly slower decrease rate of Pn than wild type 6028 during the senescence progress, especially at the later stage. Furthermore, Ca2+-ATPase, Mg2+-ATPase and photophosphorylation activities exhibited the similar trends as the Pn. During the senescence process, the 68 kDa polypeptide concentrations in the thylakoid membrane proteins exhibited a significant change, which was one of the critical factors that contributed to the observed change in photosynthesis. We also observed that the chloroplasts of rice mutant 6001 exhibited higher integrity than those of wild type 6028, and the chloroplast membrane of rice mutant 6001 disintegrated more slow during the senescence process. In general, rice mutant 6001 had a relatively slower senescence rate than wild type 6028, and exhibited anti-senescence properties.

Implementing Mobile Virtual Exhibition to Increase Cultural Heritage Visibility

Directory of Open Access Journals (Sweden)

Cristian CIUREA

2014-01-01

Full Text Available The paper presents an implementation of iOS mobile application designed as a virtual exhibition, which aims to increase the accessibility and visibility of physical objects that composite cultural heritage elements. Mobile technologies have seen a huge evolution in the last years and people are very attracted by smartphones, tablets and other mobile devices. Taking into consideration the impact of mobile technologies in all the activity fields, an important research objective is to analyze the influence of mobile applications designed as virtual exhibitions on cultural heritage promotion and on people cultural needs.

Isolation of New Gravitropic Mutants under Hypergravity Conditions.

Science.gov (United States)

Mori, Akiko; Toyota, Masatsugu; Shimada, Masayoshi; Mekata, Mika; Kurata, Tetsuya; Tasaka, Masao; Morita, Miyo T

2016-01-01

Forward genetics is a powerful approach used to link genotypes and phenotypes, and mutant screening/analysis has provided deep insights into many aspects of plant physiology. Gravitropism is a tropistic response in plants, in which hypocotyls and stems sense the direction of gravity and grow upward. Previous studies of gravitropic mutants have suggested that shoot endodermal cells in Arabidopsis stems and hypocotyls are capable of sensing gravity (i.e., statocytes). In the present study, we report a new screening system using hypergravity conditions to isolate enhancers of gravitropism mutants, and we also describe a rapid and efficient genome mapping method, using next-generation sequencing (NGS) and single nucleotide polymorphism (SNP)-based markers. Using the endodermal-amyloplast less 1 ( eal1 ) mutant, which exhibits defective development of endodermal cells and gravitropism, we found that hypergravity (10 g) restored the reduced gravity responsiveness in eal1 hypocotyls and could, therefore, be used to obtain mutants with further reduction in gravitropism in the eal1 background. Using the new screening system, we successfully isolated six ene ( enhancer of eal1 ) mutants that exhibited little or no gravitropism under hypergravity conditions, and using NGS and map-based cloning with SNP markers, we narrowed down the potential causative genes, which revealed a new genetic network for shoot gravitropism in Arabidopsis .

Enterocin A mutants identified by saturation mutagenesis enhance potency towards vancomycin-resistant Enterococci.

Science.gov (United States)

McClintock, Maria K; Kaznessis, Yiannis N; Hackel, Benjamin J

2016-02-01

Vancomycin-resistant Enterococci infections are a significant clinical problem. One proposed solution is to use probiotics, such as lactic acid bacteria, to produce antimicrobial peptides at the site of infection. Enterocin A, a class 2a bacteriocin, exhibits inhibitory activity against E. faecium and E. faecalis, which account for 86% of vancomycin-resistant Enterococci infections. In this study, we aimed to engineer enterocin A mutants with enhanced potency within a lactic acid bacterial production system. Peptide mutants resulting from saturation mutagenesis at sites A24 and T27 were efficiently screened in a 96-well plate assay for inhibition of pathogen growth. Several mutants exhibit increased potency relative to wild-type enterocin A in both liquid- and solid-medium growth assays. In particular, A24P and T27G exhibit enhanced inhibition of multiple strains of E. faecium and E. faecalis, including clinically isolated vancomycin-resistant strains. A24P and T27G enhance killing of E. faecium 8 by 13 ± 3- and 18 ± 4-fold, respectively. The engineered enterocin A/lactic acid bacteria systems offer significant potential to combat antibiotic-resistant infections. © 2015 Wiley Periodicals, Inc.

PBP deletion mutants of Escherichia coli exhibit irregular distribution of MreB at the deformed zones.

Science.gov (United States)

Vijayan, Saptha; Mallick, Sathi; Dutta, Mouparna; Narayani, M; Ghosh, Anindya S

2014-02-01

MreB is a cytoskeletal protein, which is responsible for maintaining proper cellular morphology and is essential for cell survival. Likewise, penicillin-binding protein 5 (PBP5) helps in maintaining cell shape, though non-essential for survival. The contradicting feature of these two proteins paves the way for this study, wherein we attempt to draw a relation on the nature of distribution of MreB in PBP deletion mutants. The study revealed that the uniform MreB helices/patches were destabilized/disturbed at the zone of deformities of the PBP mutants, whereas the helical patterns were retained at the regions maintaining a rod shape. We interpret that MreB remains functional irrespective of its distribution being misguided by the aberrant shapes of PBP mutants.

Stress Tolerance in Doughs of Saccharomyces cerevisiae Trehalase Mutants Derived from Commercial Baker’s Yeast

Science.gov (United States)

Shima, Jun; Hino, Akihiro; Yamada-Iyo, Chie; Suzuki, Yasuo; Nakajima, Ryouichi; Watanabe, Hajime; Mori, Katsumi; Takano, Hiroyuki

1999-01-01

Accumulation of trehalose is widely believed to be a critical determinant in improving the stress tolerance of the yeast Saccharomyces cerevisiae, which is commonly used in commercial bread dough. To retain the accumulation of trehalose in yeast cells, we constructed, for the first time, diploid homozygous neutral trehalase mutants (Δnth1), acid trehalase mutants (Δath1), and double mutants (Δnth1 ath1) by using commercial baker’s yeast strains as the parent strains and the gene disruption method. During fermentation in a liquid fermentation medium, degradation of intracellular trehalose was inhibited with all of the trehalase mutants. The gassing power of frozen doughs made with these mutants was greater than the gassing power of doughs made with the parent strains. The Δnth1 and Δath1 strains also exhibited higher levels of tolerance of dry conditions than the parent strains exhibited; however, the Δnth1 ath1 strain exhibited lower tolerance of dry conditions than the parent strain exhibited. The improved freeze tolerance exhibited by all of the trehalase mutants may make these strains useful in frozen dough. PMID:10388673

Assessment of Lupin Induced Mutants for Quality Traits and Susceptibility to Callosbruchus chinensis and Heliothis armigera insects

International Nuclear Information System (INIS)

Ragab, A.I.; Boshra, S.A.; Mehany, A.L.; Darwish, A.A.; Kharrab, M.M.

2008-01-01

This study was conducted to assess 23 induced mutants and two parental varieties Giza1 and Giza2 in the three generations (M3, M4, and M5) for seed quality traits, and susceptibility to two insects i.e C. chinnensis and H.armigera. The obtained results exhibited highly significant decrease for alkaloid content of mutants 20 and 23 as compared with the two local varieties. Most of mutants and Giza 2 showed marked increase for protein content as compared with Giza1, however, the increase did not reach the level of significance for the most mutants as compared with Giza2 in the three generations. Except of M4 generation. marked resistance for infestations with C.chinensis and H.armigera was obtained for mutants 1, 5 and 11 in the three generations. However, for total infestation with the two insects, resistance was obtained in mutants 4 and 10. Except of mutant lines 1, 5 and 11, all mutants showed higher loss percentage than that of the local varieties

Isolation of new gravitropic mutants under hypergravity conditions

Directory of Open Access Journals (Sweden)

Akiko Mori

2016-09-01

Full Text Available Forward genetics is a powerful approach used to link genotypes and phenotypes, and mutant screening/analysis has provided deep insights into many aspects of plant physiology. Gravitropism is a tropistic response in plants, in which hypocotyls and stems sense the direction of gravity and grow upwards. Previous studies of gravitropic mutants have suggested that shoot endodermal cells in Arabidopsis stems and hypocotyls are capable of sensing gravity (i.e., statocytes. In the present study, we report a new screening system using hypergravity conditions to isolate enhancers of gravitropism mutants, and we also describe a rapid and efficient genome mapping method, using Next-Generation Sequencing (NGS and Single Nucleotide Polymorphism (SNP-based markers. Using the endodermal-amyloplast less 1 (eal1 mutant, which exhibits defective development of endodermal cells and gravitropism, we found that hypergravity (10 g restored the reduced gravity responsiveness in eal1 hypocotyls and could, therefore, be used to obtain mutants with further reduction in gravitropism in the eal1 background. Using the new screening system, we successfully isolated six ene (enhancer of eal1 mutants that exhibited little or no gravitropism under hypergravity conditions, and using NGS and map-based cloning with SNP markers, we narrowed down the potential causative genes, which revealed a new genetic network for shoot gravitropism in Arabidopsis.

Rubisco mutants of Chlamydomonas reinhardtii enhance photosynthetic hydrogen production.

Science.gov (United States)

Pinto, T S; Malcata, F X; Arrabaça, J D; Silva, J M; Spreitzer, R J; Esquível, M G

2013-06-01

Molecular hydrogen (H2) is an ideal fuel characterized by high enthalpy change and lack of greenhouse effects. This biofuel can be released by microalgae via reduction of protons to molecular hydrogen catalyzed by hydrogenases. The main competitor for the reducing power required by the hydrogenases is the Calvin cycle, and rubisco plays a key role therein. Engineered Chlamydomonas with reduced rubisco levels, activity and stability was used as the basis of this research effort aimed at increasing hydrogen production. Biochemical monitoring in such metabolically engineered mutant cells proceeded in Tris/acetate/phosphate culture medium with S-depletion or repletion, both under hypoxia. Photosynthetic activity, maximum photochemical efficiency, chlorophyll and protein levels were all measured. In addition, expression of rubisco, hydrogenase, D1 and Lhcb were investigated, and H2 was quantified. At the beginning of the experiments, rubisco increased followed by intense degradation. Lhcb proteins exhibited monomeric isoforms during the first 24 to 48 h, and D1 displayed sensitivity under S-depletion. Rubisco mutants exhibited a significant decrease in O2 evolution compared with the control. Although the S-depleted medium was much more suitable than its complete counterpart for H2 production, hydrogen release was observed also in sealed S-repleted cultures of rubisco mutated cells under low-moderate light conditions. In particular, the rubisco mutant Y67A accounted for 10-15-fold higher hydrogen production than the wild type under the same conditions and also displayed divergent metabolic parameters. These results indicate that rubisco is a promising target for improving hydrogen production rates in engineered microalgae.

Mutant Mice Lacking the p53 C-Terminal Domain Model Telomere Syndromes

NARCIS (Netherlands)

Simeonova, I.; Jaber, S.; Draskovic, I.; Bardot, B.; Fang, M.; Bouarich-Bourimi, R.; Lejour, V.; Charbonnier, L.; Soudais, C.; Bourdon, J.C.; Huerre, M.; Londono-Vallejo, A.; Toledo, F.

2013-01-01

Mutations in p53, although frequent in human cancers, have not been implicated in telomere-related syndromes. Here, we show that homozygous mutant mice expressing p53(Delta31), a p53 lacking the C-terminal domain, exhibit increased p53 activity and suffer from aplastic anemia and pulmonary fibrosis,

Purification, gene cloning, gene expression, and mutants of Dps from the obligate anaerobe Porphyromonas gingivalis.

Science.gov (United States)

Ueshima, Junichi; Shoji, Mikio; Ratnayake, Dinath B; Abe, Kihachiro; Yoshida, Shinichi; Yamamoto, Kenji; Nakayama, Koji

2003-03-01

The periodontopathogen Porphyromonas gingivalis is an obligate anaerobe that is devoid of catalase but exhibits a relatively high degree of resistance to peroxide stress. In the present study, we demonstrate that P. gingivalis contains a Dps homologue that plays an important role in the protection of cells from peroxide stress. The Dps protein isolated from P. gingivalis displayed a ferritin-like spherical polymer consisting of 19-kDa subunits. Molecular cloning and sequencing of the gene encoding this protein revealed that it had a high similarity in nucleotide and amino acid sequences to Dps proteins from other species. The expression of Dps was significantly increased by exposure of P. gingivalis to atmospheric oxygen in an OxyR-dependent manner, indicating that it is regulated by the reactive oxygen species-regulating gene oxyR. The Dps-deficient mutants, including the dps single mutant and the ftn dps double mutant, showed no viability loss upon exposure to atmospheric oxygen for 6 h. In contrast to the wild type, however, these mutants exhibited the high susceptibility to hydrogen peroxide, thereby disrupting the viability. On the other hand, no significant difference in sensitivity to mitomycin C and metronidazole was observed between the wild type and the mutants. Furthermore, the dps single mutant, compared with the wild type, showed a lower viability in infected human umbilical vein endothelial cells.

Repair of gamma radiation damage in wild type and a radiation sensitive mutant of Deinococcus radiodurans

International Nuclear Information System (INIS)

Mizuma, Nagayo

1989-01-01

In an effort to examine production and repair of radiation-induced single and double strand breaks in the DNA, a repair-deficient wild type and a repair-deficient mutant, UV17, of Deinococcus radiodurans were subjected to Co-60 gamma irradiation at a dose rate of 6.3 kGy/hr for wild type and 3.9 kGy/hr for UV17 mutant. The shoulder of the curve of UV17 mutant was narrow but existed with the intercept of 0.7 kGy and the corresponding value of the wild type was 4.2 kGy. Mutant cells exhibited about 6 fold increases in sensitivity for the shoulder relative to the wild type. The D 37 doses in the wild type and the mutant were 0.57 kGy and 0.25 kGy, respectively. From the survival curves, difference in the sensitivity between two strains was mainly due to difference of repair capacity than the number of radiation sensitive target. Sedimentation rate of the main component in the irradiated cells of UV17 mutant increased almost to the level of unirradiated control by the postincubation at 30deg C for 3 hrs. The results indicated that this sensitive mutant also exhibited an ability to restore single strand breaks after exposure to a sublethal dose of 0.6 kGy. When restitution of double strand breaks was analyzed by sedimentation in a neutral sucrose gradient, the wild type showed restitution to DNA-membrane complex from large part of the breaks. For UV17 mutant, the apparent increase in DNA-membrane complex formation was seen after 3 hours incubation. Large part of the decrease in the activities of peak 2 was recovered in the peak 1 for the wild type. For the mutant, there was little restitution to peak 1. Almost free DNA component in UV17 mutant, therefore, was merely degraded into shorter pieces. Restoration of DNA-membrane complex from free DNA derived from gamma-ray induced double strand scission involved closely in the repair of gamma-induced damage and survival. (N.K.)

Temperature sensitive riboflavin mutants of Penicillium vermiculatum Dangeard

International Nuclear Information System (INIS)

Mitra, J.; Chaudhari, K.L.

1974-01-01

Two temperature sensitive UV induced riboflavin mutants rib 1 and rib 6 have been physiologically and genetically characterized. The two mutants behave differently with regard to their temperature sensitivity. The rib 1 mutant exhibits a leaky growth in minimal medium between 15 0 C and 30 0 C but grows well when the medium is supplemented with riboflavin. At 35 0 C the growth response of the mutant is at its max. and at 40 0 C and below 15 0 C it ceases to grow. The rib 6 mutant which is red brown in colour shows wild type character at temp. below 25 0 C in minimal medium but requires riboflavin at 30 0 C and above. Heterokaryotic analysis revealed the nonallelic nature of the two temperature mutants. Genetic tests of allelic relationship between riboflavin markers by crossing were also done. (author)

Molecular Mechanisms Regulating Ocular Apoptosis in Zebrafish gdf6a Mutants

DEFF Research Database (Denmark)

Pant, Sameer D.; March, Lindsey D.; Famulski, Jakub K.

2013-01-01

intrinsic or extrinsic apoptotic mechanisms were involved, morpholino antisense oligonucleotides targeting baxa, baxb, and p53 were employed. Caspase-3 immunohistochemistry (IHC) was performed to assay apoptosis. Pharmacologic inhibition (using SB203580) and IHC were used to investigate the role of p38...... occurs 28 hours post fertilization (hpf) in gdf6a(-/-) mutants that is mediated independently of p53 by intrinsic mechanisms involving Bax proteins. Also, gdf6a(-/-) mutants exhibit markedly increased p38 MAP kinase activation that can be inhibited to significantly reduce retinal apoptosis. A reduction...... in retinal smad1 expression was also noted in gdf6a(-/-) mutants. CONCLUSIONS. gdf6a(-/-)-induced apoptosis is characterized by the involvement of intrinsic apoptotic pathways, p38 MAP kinases, and dysregulated smad expression. Modulation of key mediators can inhibit retinal apoptosis offering potential...

Yield and Quality Traits of some Rice Mutant Lines as Affected by Different Nitrogen Levels

International Nuclear Information System (INIS)

Sobieh, S.El-S.S.

2007-01-01

Two field experiments were carried out during two growing seasons (2004 and 2005) at a farm located in Sahafa village, Sharkia Governorate, to evaluate newly rice mutants comparing with the local cultivar Sakha 104 for yield and quality characteristics as affected by nitrogen fertilizer levels. The obtained results showed that: 1- Rice grain yield and yield attributes were significantly increased with increasing N levels from 23 to 69 kg N fed '. 2- Both mutant MG 16 and MS 6 exhibited highly significant increases in mean values for yield attributes except for number of panicles/m2, as compared with the local cultivar Sakha 104. 3- Percentage of yield increases were 26.85 and 16.21 % for mutant MG16 and MS6 comparing with the local variety Sakha 104, respectively. Mutant MG 16 showed the highest mean values for plant height, panicle length, number of grains per panicle, panicle weight, 1000-grain weight, grain yield/fed, and straw yield/fed, as compared with the mutant MS 6 and Sakha 104. 4- Hulling and milling % were significantly increased as increasing of nitrogen levels from 23 to 69 kg N fed 1 , whereas head rice, gel consistency and amylose content were not significantly affect. 5- Significant differences were obtained between the three rice genotypes for hulling %, milling %, head rice %, amylose content and gel consistency

Excision-repair in mutants of Escherichia coli deficient in DNA polymerase I and/or its associated 5'. -->. 3' exonuclease

Energy Technology Data Exchange (ETDEWEB)

Cooper, P [Stanford Univ., Calif. (USA). Dept. of Biological Sciences

1977-01-01

The UV sensitivity of E.coli mutants deficient in the 5'..-->..3' exonuclease activity of DNA polymerase I is intermediate between that of pol/sup +/ strains and mutants which are deficient in the polymerizing activity of pol I (polA1). Like polA1 mutants, the 5'-econuclease deficient mutants exhibit increased UV-induced DNA degradation and increased repair synthesis compared to a pol/sup +/ strain, although the increase is not as great as in polA1 or in the conditionally lethal mutant BT4113ts deficient in both polymerase I activities. When dimer excision was measured at UV doses low enough to avoid interference from extensive DNA degradation, all three classes of polymerase I deficient mutants were found to remove dimers efficiently from their DNA. We conclude that enzymes alternative to polymerase I can operate in both the excision and resynthesis steps of excision repair and that substitution for either of the polymerase I functions results in longer patches of repair. A model is proposed detailing the possible events in the alternative pathways.

Molecular characterization of thymidine kinase mutants of human cells induced by densely ionizing radiation

Energy Technology Data Exchange (ETDEWEB)

Kronenberg, A; Little, J B

1989-04-01

In order to characterize the nature of mutants induced by densely ionizing radiations at an autosomal locus, the authors have isolated a series of 99 thymidine kinase (tk) mutants of human TK6 lymphoblastoid cells iraadiated with either fast neutrons or accelerated argon ions. Individual muant clones were examined for alterations in their restriction fragment pattern after hybridization with a human cDNA probe for tk. A restriction fragment length polymorphism (RFLP) allowed identification of the active tk allele. Among the neutron-induced mutants, 34/52 exhibited loss of the previously active allele while 6/52 exhibited intragenic rearrangements. Among the argon-induced mutants 27/46 exhibited allele loses and 10/46 showed rearrangements within the tk locus. The remaining mutants had restriction patterns indistinguishable from the TK6 parent. Each of the mutant clones was further examined for structural alterations within the c-erbAl locus which has been localized to chromosome 17q11-q22, at some unknown distance from the human tk locus at chromosome 17q21-q22. A substantial proportion (54%) of tk mutants induced by densely ionizing radiation showed loss of the c-erb locus on the homologous chromosome, suggesting that the mutations involve large-scale genetic changes. (author). 51 refs.; 2 figs.; 6 tabs.

Knockin mouse with mutant Gα11 mimics human inherited hypocalcemia and is rescued by pharmacologic inhibitors

DEFF Research Database (Denmark)

Roszko, Kelly L; Bi, Ruiye; Gorvin, Caroline M

2017-01-01

in patients with autosomal-dominant hypocalcemia type 2 (ADH2), an inherited disorder of hypocalcemia, low parathyroid hormone (PTH), and hyperphosphatemia. We have generated knockin mice harboring the point mutation GNA11 c.C178T (p.Arg60Cys) identified in ADH2 patients. The mutant mice faithfully replicated...... human ADH2. They also exhibited low bone mineral density and increased skin pigmentation. Treatment with NPS 2143, a negative allosteric modulator of the calcium-sensing receptor (CASR), increased PTH and calcium concentrations in WT and mutant mice, suggesting that the gain-of-function effect of GNA11...

Hypermutability of a UV-sensitive aphidicolin-resistant mutant of Chinese hamster fibroblasts

International Nuclear Information System (INIS)

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

1982-01-01

An ultraviolet light (UV)-sensitive thymidine auxotroph of Chinese hamster V79 cells that exhibits pleiotropic effects such as a high level of deoxycytidine triphosphate, slow growth, sensitivity to cytidine, and high frequencies of site-specific bromodeoxyuridine-dependent chromosomal aberrations was selected by its resistance to aphidicolin. The UV-induced mutability of this mutant and one of its revertants, which retains some of the phenotypes listed above, was studied in 3 mutation assay systems. The results showed that the mutant was hypermutable for ouabain and diphtheria-toxin-resistant mutations compared to wild-type V79 cells at the same UV dose or the same survival level. The mutant exhibits a delayed expression of maximal frequency of induced 6-thioguanine-resistant mutants. When maximal frequencies are compared at the same UV dose, the mutant also has higher mutation frequencies at the hypoxanthine-guanine phosphoribosyl transferase locus. The revertant was similar to the wild-type in UV sensitivity and mutability. (orig./AJ)

Potency of carbapenems for the prevention of carbapenem-resistant mutants of Pseudomonas aeruginosa: the high potency of a new carbapenem doripenem.

Science.gov (United States)

Sakyo, Shihomi; Tomita, Haruyoshi; Tanimoto, Koichi; Fujimoto, Shuhei; Ike, Yasuyoshi

2006-04-01

The potencies of the carbapenems; doripenem (DRPM), meropenem (MEPM) and imipenem (IPM) in preventing the emergence of carbapenem-resistant mutants were examined in Pseudomonas aeruginosa strains. The carbapenems predominantly selected carbapenem-resistant mutants or carbapenem mutants with reduced susceptibilities that were specifically resistant to carbapenems and had arisen as a result of the reduced level of expression of the outer membrane protein with a molecular weight of about 48,000 (OprD). The potency of carbapenems in preventing the growth of the mutants differed for DRPM, MEPM and IPM. The isolation frequency of the mutant was examined on agar plates containing each of the carbapenems at a concentration of 1/2 or 1/4 MIC of each carbapenem for that mutant. Mutants were not selected on agar containing DRPM at a frequency of greater than 10(-9) per cell per generation, whereas mutants of each strain were selected on agar containing MEPM or IPM at frequencies of 10(-7) to 10(-9) per cell per generation. The drug concentrations and the drug concentration range for the selective increase of carbapenem resistant mutants in the broth culture containing each carbapenem differed for each carbapenem. DRPM exhibited both the lowest drug concentration and the narrowest range of drug concentration for selection of the carbapenem-resistant mutants. The results shown in this report indicated that DRPM exhibited the greatest ability to prevent the emergence of the mutant.

Isolation of glutathione-deficient mutants of the yeast Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Kistler, M.; Eckardt, F.; Summer, K.-H.

1986-01-01

Glutathione-deficient (gsh - ) mutants of the yeast Saccharomyces cerevisiae were isolated after UV treatment using MNNG as selective agent. For genetic and biochemical characterization 5 mutant strains were chosen which exhibited considerably decreased residual GSH contents varying from 2 to 6% of the wild-type levels. All 5 isolates showed a 2:2 segregation of the gsh - :GSH + phenotypes alluding to a monogenic recessive mutation. Complementation analysis indicates that all gsh - mutants belong to one complementation group. (Auth.)

A cGMP kinase mutant with increased sensitivity to the protein kinase inhibitor peptide PKI(5-24).

Science.gov (United States)

Ruth, P; Kamm, S; Nau, U; Pfeifer, A; Hofmann, F

1996-01-01

Synthetic peptides corresponding to the active domain of the heat-stable inhibitor protein PKI are very potent inhibitors of cAMP-dependent protein kinase, but are extremely weak inhibitors of cGMP-dependent protein kinase. In this study, we tried to confer PKI sensitivity to cGMP kinase by site-directed mutagenesis. The molecular requirements for high affinity inhibition by PKI were deduced from the crystal structure of the cAMP kinase/PKI complex. A prominent site of interaction are residues Tyr235 and Phe239 in the catalytic subunit, which from a sandwich-like structure with Phe10 of the PKI(5-24) peptide. To increase the sensitivity for PKI, the cGMP kinase codons at the corresponding sites, Ser555 and Ser559, were changed to Tyr and Phe. The mutant cGMP kinase was stimulated half maximally by cGMP at 3-fold higher concentrations (240 nM) than the wild type (77 nM). Wild type and mutant cGMP kinase did not differ significantly in their Km and Vmax for three different substrate peptides. The PKI(5-24) peptide inhibited phosphotransferase activity of the mutant cGMP kinase with higher potency than that of wild type, with Ki values of 42 +/- .3 microM and 160 +/- .7 microM, respectively. The increased affinity of the mutant cGMP kinase was specific for the PKI(5-24) peptide. Mutation of the essential Phe10 in the PKI(5-24) sequence to an Ala yielded a peptide that inhibited mutant and wild type cGMP kinase with similar potency, with Ki values of 160 +/- 11 and 169 +/- 27 microM, respectively. These results suggest that the mutations Ser555Tyr and Ser559Phe are required, but not sufficient, for high affinity inhibition of cGMP kinase by PKI.

Spirogyra varians mutant generated by high dose gamma-irradiation shows increased antioxidant properties

International Nuclear Information System (INIS)

Lee, Hak-Jyung; Yoon, Minchul; Sung, Nak-Yun; Choi, Jong-il

2012-01-01

The aim of this study was to evaluate the antioxidant properties of a Spirogyra varians mutant (Mut) produced by gamma irradiation. Methanol extracts were prepared from Spirogyra varians wild-type and Mut plants, and their antioxidant activities and total phenolic content (TPC) were determined. Antioxidant parameters, including the 2-diphenyl-1-picrylhydrazyl radical-scavenging activity and ferric-reducing/antioxidant power, were higher in the Mut extract. Moreover, the TPC level was higher (P<0.05) in the Mut methanol extract. Therefore, these results suggest that gamma irradiation-induced S. varians Mut has superior antioxidant properties. - Highlights: ► The antioxidative properties of a Spirogyra varians mutant produced by gamma-irradiation was investiated. ► The antioxidant activities and total phenolic content levels were higher in mutant strain. ► These results suggest that gamma-irradiation induced algae mutant with superior antioxidant properties.

Data supporting mitochondrial morphological changes by SPG13-associated HSPD1 mutants

Directory of Open Access Journals (Sweden)

Yuki Miyamoto

2016-03-01

Full Text Available The data is related to the research article entitled “Hypomyelinating leukodystrophy-associated missense mutation in HSPD1 blunts mitochondrial dynamics” [1]. In addition to hypomyelinating leukodystrophy (HLD 4 (OMIM no. 612233, it is known that spastic paraplegia (SPG 13 (OMIM no. 605280 is caused by HSPD1’s amino acid mutation. Two amino acid mutations Val-98-to-Ile (V98I and Gln-461-to-Glu (Q461E are associated with SPG13 [2]. In order to investigate the effects of HSPD1’s V98I or Q461E mutant on mitochondrial morphological changes, we transfected each of the respective mutant-encoding genes into Cos-7 cells. Either of V98I or Q461E mutant exhibited increased number of mitochondria and short length mitochondrial morphologies. Using MitoTracker dye-incorporating assay, decreased mitochondrial membrane potential was also observed in both cases. The data described here supports that SPG13-associated HSPD1 mutant participates in causing aberrant mitochondrial morphological changes with decreased activities. Keywords: SPG13, HSPD1, Mitochondrion, Morphological change

Sucralose Increases Antimicrobial Resistance and Stimulates Recovery of Escherichia coli Mutants.

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Qu, Yilin; Li, Rongyan; Jiang, Mingshan; Wang, Xiuhong

2017-07-01

Because of heavy use of antimicrobials, antimicrobial resistance in bacteria has become of great concern. The effect of some widely used food additives such as sucralose on bacteria in the gut and the environment has also drawn increasing attention. In this study, we investigated the interaction between antimicrobials and sucralose impacting antimicrobial resistance and mutation of Escherichia coli (E. coli). To examine antimicrobial resistance and mutation frequency, different subinhibitory concentrations of sucralose were added to cultures of E.coli BW25113 that were then treated with antimicrobials, oxolinic acid, or moxifloxacin. Then the E.coli were assayed for bacterial survival and recovery of mutants resistant to an unrelated antimicrobial, rifampicin. Pre-treatment of E.coli BW25113 with 1/2 minimal inhibitory concentration (MIC) of sucralose increased the survival rate in oxolinic acid or moxifloxacin. A 1/3 MIC of sucralose increased rifampicin-resistant mutation rate of E.coli BW25113 after 72 h, while rifampicin-resistant mutation rate was increased when co-treated with 1/8 MIC, 1/4 MIC, 1/3 MIC sucralose, and oxolinic acid after 24 h. Sucralose can increase the antimicrobial resistance and mutation frequency of E.coli to some antimicrobials.

An ALS-linked mutant SOD1 produces a locomotor defect associated with aggregation and synaptic dysfunction when expressed in neurons of Caenorhabditis elegans.

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Jiou Wang

2009-01-01

Full Text Available The nature of toxic effects exerted on neurons by misfolded proteins, occurring in a number of neurodegenerative diseases, is poorly understood. One approach to this problem is to measure effects when such proteins are expressed in heterologous neurons. We report on effects of an ALS-associated, misfolding-prone mutant human SOD1, G85R, when expressed in the neurons of Caenorhabditis elegans. Stable mutant transgenic animals, but not wild-type human SOD1 transgenics, exhibited a strong locomotor defect associated with the presence, specifically in mutant animals, of both soluble oligomers and insoluble aggregates of G85R protein. A whole-genome RNAi screen identified chaperones and other components whose deficiency increased aggregation and further diminished locomotion. The nature of the locomotor defect was investigated. Mutant animals were resistant to paralysis by the cholinesterase inhibitor aldicarb, while exhibiting normal sensitivity to the cholinergic agonist levamisole and normal muscle morphology. When fluorescently labeled presynaptic components were examined in the dorsal nerve cord, decreased numbers of puncta corresponding to neuromuscular junctions were observed in mutant animals and brightness was also diminished. At the EM level, mutant animals exhibited a reduced number of synaptic vesicles. Neurotoxicity in this system thus appears to be mediated by misfolded SOD1 and is exerted on synaptic vesicle biogenesis and/or trafficking.

Human GLTP and mutant forms of ACD11 suppress cell death in the Arabidopsis acd11 mutant

DEFF Research Database (Denmark)

Petersen, Nikolaj H T; McKinney, Lea V; Pike, Helen

2008-01-01

The Arabidopsis acd11 mutant exhibits runaway, programmed cell death due to the loss of a putative sphingosine transfer protein (ACD11) with homology to mammalian GLTP. We demonstrate that transgenic expression in Arabidopsis thaliana of human GLTP partially suppressed the phenotype of the acd11...

Mutant IDH1 Promotes Glioma Formation In Vivo

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Beatrice Philip

2018-05-01

Full Text Available Summary: Isocitrate dehydrogenase 1 (IDH1 is the most commonly mutated gene in grade II–III glioma and secondary glioblastoma (GBM. A causal role for IDH1R132H in gliomagenesis has been proposed, but functional validation in vivo has not been demonstrated. In this study, we assessed the role of IDH1R132H in glioma development in the context of clinically relevant cooperating genetic alterations in vitro and in vivo. Immortal astrocytes expressing IDH1R132H exhibited elevated (R-2-hydroxyglutarate levels, reduced NADPH, increased proliferation, and anchorage-independent growth. Although not sufficient on its own, IDH1R132H cooperated with PDGFA and loss of Cdkn2a, Atrx, and Pten to promote glioma development in vivo. These tumors resembled proneural human mutant IDH1 GBM genetically, histologically, and functionally. Our findings support the hypothesis that IDH1R132H promotes glioma development. This model enhances our understanding of the biology of IDH1R132H-driven gliomas and facilitates testing of therapeutic strategies designed to combat this deadly disease. : Philip et al. show that mutant IDH1 cooperates with PDGFA and loss of Cdkn2a, Atrx, and Pten to promote gliomagenesis in vivo in a mouse model of glioma. These tumors resemble proneural human mutant IDH1 glioblastoma and exhibit enhanced sensitivity to PARP inhibition in combination with chemotherapy. Keywords: IDH1, Cdkn2a, Atrx, Pten, glioma, mouse model, RCAS/TVA

Recombinant deamidated mutants of Erwinia chrysanthemi L-asparaginase have similar or increased activity compared to wild-type enzyme.

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Gervais, David; Foote, Nicholas

2014-10-01

The enzyme Erwinia chrysanthemi L-asparaginase (ErA) is an important biopharmaceutical product used in the treatment of acute lymphoblastic leukaemia. Like all proteins, certain asparagine (Asn) residues of ErA are susceptible to deamidation to aspartic acid (Asp), which may be a concern with respect to enzyme activity and potentially to pharmaceutical efficacy. Recombinant ErA mutants containing Asn to Asp changes were expressed, purified and characterised. Two mutants with single deamidation sites (N41D and N281D) were found to have approximately the same specific activity (1,062 and 924 U/mg, respectively) as the wild-type (908 U/mg). However, a double mutant (N41D N281D) had an increased specific activity (1261 U/mg). The N41D mutation conferred a slight increase in the catalytic constant (k cat 657 s(-1)) when compared to the WT (k cat 565 s(-1)), which was further increased in the double mutant, with a k cat of 798 s(-1). Structural analyses showed that the slight changes caused by point mutation of Asn41 to Asp may have reduced the number of hydrogen bonds in this α-helical part of the protein structure, resulting in subtle changes in enzyme turnover, both structurally and catalytically. The increased α-helical content observed with the N41D mutation by circular dichroism spectroscopy correlates with the difference in k cat, but not K m. The N281D mutation resulted in a lower glutaminase activity compared with WT and the N41D mutant, however the N281D mutation also imparted less stability to the enzyme at elevated temperatures. Taken as a whole, these data suggest that ErA deamidation at the Asn41 and Asn281 sites does not affect enzyme activity and should not be a concern during processing, storage or clinical use. The production of recombinant deamidated variants has proven an effective and powerful means of studying the effect of these changes and may be a useful strategy for other biopharmaceutical products.

Functional Loss of Bmsei Causes Thermosensitive Epilepsy in Contractile Mutant Silkworm, Bombyx mori

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Nie, Hongyi; Cheng, Tingcai; Huang, Xiaofeng; Zhou, Mengting; Zhang, Yinxia; Dai, Fangyin; Mita, Kazuei; Xia, Qingyou; Liu, Chun

2015-07-01

The thermoprotective mechanisms of insects remain largely unknown. We reported the Bombyx mori contractile (cot) behavioral mutant with thermo-sensitive seizures phenotype. At elevated temperatures, the cot mutant exhibit seizures associated with strong contractions, rolling, vomiting, and a temporary lack of movement. We narrowed a region containing cot to ~268 kb by positional cloning and identified the mutant gene as Bmsei which encoded a potassium channel protein. Bmsei was present in both the cell membrane and cytoplasm in wild-type ganglia but faint in cot. Furthermore, Bmsei was markedly decreased upon high temperature treatment in cot mutant. With the RNAi method and injecting potassium channel blockers, the wild type silkworm was induced the cot phenotype. These results demonstrated that Bmsei was responsible for the cot mutant phenotype and played an important role in thermoprotection in silkworm. Meanwhile, comparative proteomic approach was used to investigate the proteomic differences. The results showed that the protein of Hsp-1 and Tn1 were significantly decreased and increased on protein level in cot mutant after thermo-stimulus, respectively. Our data provide insights into the mechanism of thermoprotection in insect. As cot phenotype closely resembles human epilepsy, cot might be a potential model for the mechanism of epilepsy in future.

Characterization of induced mutants of Sesame (Sesamum indicum L) for confectionary and quality traits

International Nuclear Information System (INIS)

Masur, Shakuntala; Madhusudan, K.

2009-01-01

Sesame induced mutants were isolated from gamma irradiation of a local variety DS-1. The promising mutants for high yield and bold seed were utilized for assessing lignan profiles mainly sesamin, sesamolin and gamma tocopherol.mutant-1022 exhibited 146 per cent improvement over the parent, Since, the sesame possess numerous health benefits, the value added confectionary products were prepared. The studies revealed that, the biscuits prepared by using 100 per cent sesame flour exhibited very good spreading quality and baking strength. Organoleptic score indicated that 80% of the evaluators accepted biscuits prepared from pure sesame flour. (author)

Peramivir analogues bearing hydrophilic side chains exhibit higher activities against H275Y mutant than wild-type influenza virus.

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Chiu, Din-Chi; Lin, Tzu-Chen; Huang, Wen-I; Cheng, Ting-Jen; Tsai, Keng-Chang; Fang, Jim-Min

2017-11-29

Peramivir is an effective anti-influenza drug in the clinical treatment of influenza, but its efficacy toward the H275Y mutant is reduced. The previously reported cocrystal structures of inhibitors in the mutant neuraminidase (NA) suggest that the hydrophobic side chain should be at the origin of reduced binding affinity. In contrast, zanamivir having a hydrophilic glycerol side chain still possesses high affinity toward the H275Y NA. We thus designed five peramivir analogues (5-9) carrying hydrophilic glycol or glycerol side chains, and evaluated their roles in anti-influenza activity, especially for the H275Y mutant. The synthetic sequence involves a key step of (3 + 2) cycloaddition reactions between alkenes and nitrile oxides to construct the scaffold of peramivir carrying the desired hydrophilic side chains and other appropriate functional groups. The molecular docking experiments reveal that the hydrophilic side chain can provide extra hydrogen bonding with the translocated Glu-276 residue in the H275Y NA active site. Thus, the H275Y mutant may be even more sensitive than wild-type virus toward the peramivir analogues bearing hydrophilic side chains. Notably, the peramivir analogue bearing a glycerol side chain inhibits the H275Y mutant with an IC 50 value of 35 nM, which is better than the WSN virus by 9 fold.

Mutants of alfalfa mosaic virus

International Nuclear Information System (INIS)

Roosien, J.

1983-01-01

In this thesis the isolation and characterization of a number of mutants of alfalfa mosaic virus, a plant virus with a coat protein dependent genome, is described. Thermo-sensitive (ts) mutants were selected since, at least theoretically, ts mutations can be present in all virus coded functions. It was found that a high percentage of spontaneous mutants, isolated because of their aberrant symptoms, were ts. The majority of these isolates could grow at the non-permissive temperature in the presence of a single wild type (wt) component. To increase the mutation rate virus preparations were treated with several mutagens. After nitrous acid treatment or irradiation with ultraviolet light, an increase in the level of mutations was observed. UV irradiation was preferred since it did not require large amounts of purified viral components. During the preliminary characterization of potential ts mutants the author also obtained one structural and several symptom mutants which were analysed further (chapter 7, 8 and 9). The properties of the ts mutants are described in chapter 3-7. (Auth.)

Isolation of a spontaneous CHO amino acid transport mutant by a combination of tritium suicide and replica plating

International Nuclear Information System (INIS)

Dantzig, A.H.; Slayman, C.W.; Adelberg, E.A.

1982-01-01

A spontaneous transport mutant of Chinese hamster ovary cells, CHY-1, was isolated by a combination of [ 3 H]proline suicide and replica plating. The mutant took up less tritium than the parent, resulting in a lower killing rate during storage. Transport by four separate amino acid transport systems (A, ASC, L, Ly+) was examined. The CHY-1 mutant exhibited normal uptake via the ASC, L, and Ly+ systems. By contrast, uptake of the most specific substrate of the A system, 2-(methylamino)-isobutyric acid, was significantly reduced at low, but not high, concentrations, due to a 3.5-fold increase in Km and a 1.5-fold increase in Vmax. Taken together, these data suggest that the CHY-1 mutation may be in the structural gene coding for the A transport protein. The tritium suicide procedure is discussed, and general equations are derived to predict the maximum storage time for the survival of one mutant cell and the optimum size of the cell population for maximum mutant enrichment

Characterization and fine mapping of a light-dependent leaf lesion mimic mutant 1 in rice.

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Wang, Jing; Ye, Bangquan; Yin, Junjie; Yuan, Can; Zhou, Xiaogang; Li, Weitao; He, Min; Wang, Jichun; Chen, Weilan; Qin, Peng; Ma, Bintian; Wang, Yuping; Li, Shigui; Chen, Xuewei

2015-12-01

Plants that spontaneously produce lesion mimics or spots, without any signs of obvious adversity, such as pesticide and mechanical damage, or pathogen infection, are so-called lesion mimic mutants (lmms). In rice, many lmms exhibit enhanced resistance to pathogens, which provides a unique opportunity to uncover the molecular mechanism underlying lmms. We isolated a rice light-dependent leaf lesion mimic mutant 1 (llm1). Lesion spots appeared in the leaves of the llm1 mutant at the tillering stage. Furthermore, the mutant llm1 had similar agronomic traits to wild type rice. Trypan blue and diamiobenzidine staining analyses revealed that the lesion spot formation on the llm1 mutant was due to programmed cell death and reactive oxygen species. The chloroplasts were severely damaged in the llm1 mutant, suggesting that chloroplast damage was associated with the formation of lesion spots in llm1. More importantly, llm1 exhibited enhanced resistance to bacterial blight pathogens within increased expression of pathogenesis related genes (PRs). Using a map-based cloning approach, we delimited the LLM1 locus to a 121-kb interval between two simple sequence repeat markers, RM17470 and RM17473, on chromosome 4. We sequenced the candidate genes on the interval and found that a base mutation had substituted adenine phosphate for thymine in the last exon of LOC_Os04g52130, which led to an amino acid change (Asp(388) to Val) in the llm1 mutant. Our investigation showed that the putative coproporphyrinogen III oxidase (CPOX) encoded by LOC_Os04g52130 was produced by LLM1 and that amino acid Asp(388) was essential for CPOX function. Our study provides the basis for further investigations into the mechanism underlying lesion mimic initiation associated with LLM1. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Identification of Potential Calorie Restriction-Mimicking Yeast Mutants with Increased Mitochondrial Respiratory Chain and Nitric Oxide Levels

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Bin Li

2011-01-01

Full Text Available Calorie restriction (CR induces a metabolic shift towards mitochondrial respiration; however, molecular mechanisms underlying CR remain unclear. Recent studies suggest that CR-induced mitochondrial activity is associated with nitric oxide (NO production. To understand the role of mitochondria in CR, we identify and study Saccharomyces cerevisiae mutants with increased NO levels as potential CR mimics. Analysis of the top 17 mutants demonstrates a correlation between increased NO, mitochondrial respiration, and longevity. Interestingly, treating yeast with NO donors such as GSNO (S-nitrosoglutathione is sufficient to partially mimic CR to extend lifespan. CR-increased NO is largely dependent on mitochondrial electron transport and cytochrome c oxidase (COX. Although COX normally produces NO under hypoxic conditions, CR-treated yeast cells are able to produce NO under normoxic conditions. Our results suggest that CR may derepress some hypoxic genes for mitochondrial proteins that function to promote the production of NO and the extension of lifespan.

Increasing the Thermostable Sugar-1-Phosphate Nucleotidylyltransferase Activities of the Archaeal ST0452 Protein through Site Saturation Mutagenesis of the 97th Amino Acid Position.

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Honda, Yuki; Zang, Qian; Shimizu, Yasuhiro; Dadashipour, Mohammad; Zhang, Zilian; Kawarabayasi, Yutaka

2017-02-01

The ST0452 protein is a bifunctional protein exhibiting sugar-1-phosphate nucleotidylyltransferase (sugar-1-P NTase) and amino-sugar-1-phosphate acetyltransferase activities and was isolated from the thermophilic archaeon Sulfolobus tokodaii Based on the previous observation that five single mutations increased ST0452 sugar-1-P NTase activity, nine double-mutant ST0452 proteins were generated with the intent of obtaining enzymes exhibiting a further increase in catalysis, but all showed less than 15% of the wild-type N-acetyl-d-glucosamine-1-phosphate uridyltransferase (GlcNAc-1-P UTase) activity. The Y97A mutant exhibited the highest activity of the single-mutant proteins, and thus site saturation mutagenesis of the 97th position (Tyr) was conducted. Six mutants showed both increased GlcNAc-1-P UTase and glucose-1-phosphate uridyltransferase activities, eight mutants showed only enhanced GlcNAc-1-P UTase activity, and six exhibited higher GlcNAc-1-P UTase activity than that of the Y97A mutant. Kinetic analyses of three typical mutants indicated that the increase in sugar-1-P NTase activity was mainly due to an increase in the apparent k cat value. We hypothesized that changing the 97th position (Tyr) to a smaller amino acid with similar electronic properties would increase activity, and thus the Tyr at the corresponding 103rd position of the Escherichia coli GlmU (EcGlmU) enzyme was replaced with the same residues. The Y103N mutant EcGlmU showed increased GlcNAc-1-P UTase activity, revealing that the Tyr at the 97th position of the ST0452 protein (103rd position in EcGlmU) plays an important role in catalysis. The present results provide useful information regarding how to improve the activity of natural enzymes and how to generate powerful enzymes for the industrial production of sugar nucleotides. It is typically difficult to increase enzymatic activity by introducing substitutions into a natural enzyme. However, it was previously found that the ST0452 protein

Characterization of a Weak Allele of Zebrafish cloche Mutant

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Ma, Ning; Huang, Zhibin; Chen, Xiaohui; He, Fei; Wang, Kun; Liu, Wei; Zhao, Linfeng; Xu, Xiangmin; Liao, Wangjun; Ruan, Hua; Luo, Shenqiu; Zhang, Wenqing

2011-01-01

Hematopoiesis is a complicated and dynamic process about which the molecular mechanisms remain poorly understood. Danio rerio (zebrafish) is an excellent vertebrate system for studying hematopoiesis and developmental mechanisms. In the previous study, we isolated and identified a cloche 172 (clo 172) mutant, a novel allele compared to the original cloche (clo) mutant, through using complementation test and initial mapping. Here, according to whole mount in-situ hybridization, we report that the endothelial cells in clo 172 mutant embryos, although initially developed, failed to form the functional vascular system eventually. In addition, further characterization indicates that the clo 172 mutant exhibited weaker defects instead of completely lost in primitive erythroid cells and definitive hematopoietic cells compared with the clo s5 mutant. In contrast, primitive myeloid cells were totally lost in clo 172 mutant. Furthermore, these reappeared definitive myeloid cells were demonstrated to initiate from the remaining hematopoietic stem cells (HSCs) in clo 172 mutant, confirmed by the dramatic decrease of lyc in clo 172 runx1w84x double mutant. Collectively, the clo 172 mutant is a weak allele compared to the clo s5 mutant, therefore providing a model for studying the early development of hematopoietic and vascular system, as well as an opportunity to further understand the function of the cloche gene. PMID:22132109

Ceramides And Stress Signalling Intersect With Autophagic Defects In Neurodegenerative Drosophila blue cheese (bchs) Mutants.

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Hebbar, Sarita; Sahoo, Ishtapran; Matysik, Artur; Argudo Garcia, Irene; Osborne, Kathleen Amy; Papan, Cyrus; Torta, Federico; Narayanaswamy, Pradeep; Fun, Xiu Hui; Wenk, Markus R; Shevchenko, Andrej; Schwudke, Dominik; Kraut, Rachel

2015-12-07

Sphingolipid metabolites are involved in the regulation of autophagy, a degradative recycling process that is required to prevent neuronal degeneration. Drosophila blue cheese mutants neurodegenerate due to perturbations in autophagic flux, and consequent accumulation of ubiquitinated aggregates. Here, we demonstrate that blue cheese mutant brains exhibit an elevation in total ceramide levels; surprisingly, however, degeneration is ameliorated when the pool of available ceramides is further increased, and exacerbated when ceramide levels are decreased by altering sphingolipid catabolism or blocking de novo synthesis. Exogenous ceramide is seen to accumulate in autophagosomes, which are fewer in number and show less efficient clearance in blue cheese mutant neurons. Sphingolipid metabolism is also shifted away from salvage toward de novo pathways, while pro-growth Akt and MAP pathways are down-regulated, and ER stress is increased. All these defects are reversed under genetic rescue conditions that increase ceramide generation from salvage pathways. This constellation of effects suggests a possible mechanism whereby the observed deficit in a potentially ceramide-releasing autophagic pathway impedes survival signaling and exacerbates neuronal death.

X-rays sensitive mammalian cell mutant

International Nuclear Information System (INIS)

Utsumi, Hiroshi

1982-01-01

A phenomenon that in x-ray-sensitive mammalian-cell mutants, cellular death due to x-ray radiation was not increased by caffeine, but on the contrary, the dead cells were resuscitated by it was discussed. The survival rate of mutant cells increased by caffein in a low concentration. This suggested that caffeine may have induced some mechanism to produce x-ray resistant mutant cells. Postirradiation treatment with caffeine increased considerably the survival rate of the mutant cells, and this suggested the existence of latent caffeine-sensitive potentially lethal damage repair system. This system, after a few hours, is thought to be substituted by caffeine-resistant repair system which is induced by caffeine, and this may be further substituted by x-ray-resistant repair system. The repair system was also induced by adenine. (Ueda, J.)

Temperature-sensitive host range mutants of herpes simplex virus type 2

International Nuclear Information System (INIS)

Koment, R.W.; Rapp, F.

1975-01-01

Herpesviruses are capable of several types of infection of a host cell. To investigate the early events which ultimately determine the nature of the virus-host cell interaction, a system was established utilizing temperature-sensitive mutants of herpes simplex virus type 2. Four mutants have been isolated which fail to induce cytopathic effects and do not replicate at 39 C in hamster embryo fibroblast cells. At least one mutant is virus DNA negative. Since intracellular complementation is detectable between pairs of mutants, a virus function is known to be temperature sensitive. However, all four mutants induce cytopathic effects and replicate to parental virus levels in rabbit kidney cells at 39 C. This suggests that a host cell function, lacking or nonfunctional in HEF cells but present in rabbit kidney cells at 39 C, is required for the replication of these mutants in hamster embryo fibroblast cells at 39 C. Therefore, we conclude that these mutants are both temperature sensitive and exhibit host range properties

Defective DNA cross-link removal in Chinese hamster cell mutants hypersensitive to bifunctional alkylating agents

International Nuclear Information System (INIS)

Hoy, C.A.; Thompson, L.H.; Mooney, C.L.; Salazar, E.P.

1985-01-01

DNA repair-deficient mutants from five genetic complementation groups isolated previously from Chinese hamster cells were assayed for survival after exposure to the bifunctional alkylating agents mitomycin C or diepoxybutane. Groups 1, 3, and 5 exhibited 1.6- to 3-fold hypersensitivity compared to the wild-type cells, whereas Groups 2 and 4 exhibited extraordinary hypersensitivity. Mutants from Groups 1 and 2 were exposed to 22 other bifunctional alkylating agents in a rapid assay that compared cytotoxicity of the mutants to the wild-type parental strain, AA8. With all but two of the compounds, the Group 2 mutant (UV4) was 15- to 60-fold more sensitive than AA8 or the Group 1 mutant (UV5). UV4 showed only 6-fold hypersensitivity to quinacrine mustard. Alkaline elution measurements showed that this compound produced few DNA interstrand cross-links but numerous strand breaks. Therefore, the extreme hypersensitivity of mutants from Groups 2 and 4 appeared specific for compounds the main cytotoxic lesions of which were DNA cross-links. Mutant UV5 was only 1- to 4-fold hypersensitive to all the compounds. Although the initial number of cross-links was similar for the three cell lines, the efficiency of removal of cross-links was lowest in UV4 and intermediate in UV5. These results suggest that the different levels of sensitivity are specifically related to different efficiencies of DNA cross-link removal. The phenotype of hypersensitivity to both UV radiation and cross-link damage exhibited by the mutants in Groups 2 and 4 appears to differ from those of the known human DNA repair syndromes

Increased production of pyruvic acid by Escherichia coli RNase G mutants in combination with cra mutations.

Science.gov (United States)

Sakai, Taro; Nakamura, Naoko; Umitsuki, Genryou; Nagai, Kazuo; Wachi, Masaaki

2007-08-01

The Escherichia coli RNase G is known as an endoribonuclease responsible for the 5'-end maturation of 16S rRNA and degradation of several specific mRNAs such as adhE and eno mRNAs. In this study, we found that an RNase G mutant derived from the MC1061 strain did not grow on a glucose minimal medium. Genetic analysis revealed that simultaneous defects of cra and ilvIH, encoding a transcriptional regulator of glycolysis/gluconeogenesis and one of isozymes of acetohydroxy acid synthase, respectively, were required for this phenomenon to occur. The results of additional experiments presented here indicate that the RNase G mutation, in combination with cra mutation, caused the increased production of pyruvic acid from glucose, which was then preferentially converted to valine due to the ilvIH mutation, resulting in depletion of isoleucine. In fact, the rng cra double mutant produced increased amount of pyruvate in the medium. These results suggest that the RNase G mutation could be applied in the breeding of producer strains of pyruvate and its derivatives such as valine.

Bending patterns of chlamydomonas flagella: III. A radial spoke head deficient mutant and a central pair deficient mutant.

Science.gov (United States)

Brokaw, C J; Luck, D J

1985-01-01

Flash photomicrography at frequencies up to 300 Hz and computer-assisted image analysis have been used to obtain parameters describing the flagellar bending patterns of mutants of Chlamydomonas reinhardtii. All strains contained the uni1 mutation, to facilitate photography. The radial spoke head deficient mutant pf17, and the central pair deficient mutant, pf15, in combination with suppressor mutations that restore motility without restoring the ultrastructural or biochemical deficiencies, both generate forward mode bending patterns with increased shear amplitude and decreased asymmetry relative to the "wild-type" uni1 flagella described previously. In the reverse beating mode, the suppressed pf17 mutants generate reverse bending patterns with large shear amplitudes. Reverse beating of the suppressed pf15 mutants is rare. There is a reciprocal relationship between increased shear amplitude and decreased beat frequency, so that the velocity of sliding between flagellar microtubules is not increased by an increase in shear amplitude. The suppressor mutations alone cause decreased frequency and sliding velocity in both forward and reverse mode beating, with little change in shear amplitude or symmetry.

Modeling the dual pacemaker system of the tau mutant hamster.

Science.gov (United States)

Oda, G A; Menaker, M; Friesen, W O

2000-06-01

Circadian pacemakers in many animals are compound. In rodents, a two-oscillator model of the pacemaker composed of an evening (E) and a morning (M) oscillator has been proposed based on the phenomenon of "splitting" and bimodal activity peaks. The authors describe computer simulations of the pacemaker in tau mutant hamsters viewed as a system of mutually coupled E and M oscillators. These mutant animals exhibit normal type 1 PRCs when released into DD but make a transition to a type 0 PRC when held for many weeks in DD. The two-oscillator model describes particularly well some recent behavioral experiments on these hamsters. The authors sought to determine the relationships between oscillator amplitude, period, PRC, and activity duration through computer simulations. Two complementary approaches proved useful for analyzing weakly coupled oscillator systems. The authors adopted a "distinct oscillators" view when considering the component E and M oscillators and a "system" view when considering the system as a whole. For strongly coupled systems, only the system view is appropriate. The simulations lead the authors to two primary conjectures: (1) the total amplitude of the pacemaker system in tau mutant hamsters is less than in the wild-type animals, and (2) the coupling between the unit E and M oscillators is weakened during continuous exposure of hamsters to DD. As coupling strength decreases, activity duration (alpha) increases due to a greater phase difference between E and M. At the same time, the total amplitude of the system decreases, causing an increase in observable PRC amplitudes. Reduced coupling also increases the relative autonomy of the unit oscillators. The relatively autonomous phase shifts of E and M oscillators can account for both immediate compression and expansion of activity bands in tau mutant and wild-type hamsters subjected to light pulses.

Biotransformation of L-tyrosine to Dopamine by a Calcium Alginate Immobilized Mutant Strain of Aspergillus oryzae.

Science.gov (United States)

Ali, Sikander; Nawaz, Wajeeha

2016-08-01

The present research work is concerned with the biotransformation of L-tyrosine to dopamine (DA) by calcium alginate entrapped conidiospores of a mutant strain of Aspergillus oryzae. Different strains of A. oryzae were isolated from soil. Out of 13 isolated strains, isolate-2 (I-2) was found to be a better DA producer. The wild-type I-2 was chemically improved by treating it with different concentrations of ethyl methyl sulfonate (EMS). Among seven mutant variants, EMS-6 exhibiting maximal DA activity of 43 μg/ml was selected. The strain was further exposed with L-cysteine HCl to make it resistant against diversion and environmental stress. The conidiospores of selected mutant variant A. oryzae EMS-6 strain were entrapped in calcium alginate beads. Different parameters for immobilization were investigated. The activity was further improved from 44 to 62 μg/ml under optimized conditions (1.5 % sodium alginate, 2 ml inoculum, and 2 mm bead size). The best resistant mutant variable exhibited over threefold increase in DA activity (62 μg/ml) than did wild-type I-2 (21 μg/ml) in the reaction mixture. From the results presented in the study, it was observed that high titers of DA activity in vitro could effectively be achieved by the EMS-induced mutagenesis of filamentous fungus culture used.

Mutant PIK3CA Induces EMT in a Cell Type Specific Manner.

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Divya Bhagirath

Full Text Available Breast cancer is characterized into different molecular subtypes, and each subtype is characterized by differential gene expression that are associated with distinct survival outcomes in patients. PIK3CA mutations are commonly associated with most breast cancer subtypes. More recently PIK3CA mutations have been shown to induce tumor heterogeneity and are associated with activation of EGFR-signaling and reduced relapse free survival in basal subtype of breast cancer. Thus, understanding what determines PIK3CA induced heterogeneity and oncogenesis, is an important area of investigation. In this study, we assessed the effect of mutant PIK3CA together with mutant Ras plus mutant p53 on oncogenic behavior of two distinct stem/progenitor breast cell lines, designated as K5+/K19- and K5+/K19+. Constructs were ectopically overexpressed in K5+/K19- and K5+/K19+ stem/progenitor cells, followed by various in-vitro and in-vivo analyses. Oncogene combination m-Ras/m-p53/m-PIK3CA efficiently transformed both K5+/K19- and K5+/K19+ cell lines in-vitro, as assessed by anchorage-independent soft agar colony formation assay. Significantly, while this oncogene combination induced a complete epithelial-to-mesenchymal transition (EMT in K5+/K19- cell line, mostly epithelial phenotype with minor EMT component was seen in K5+/K19+ cell line. However, both K5+/K19- and K5+/K19+ transformed cells exhibited increased invasion and migration abilities. Analyses of CD44 and CD24 expression showed both cell lines had tumor-initiating CD44+/CD24low cell population, however transformed K5+/K19- cells had more proportion of these cells. Significantly, both cell types exhibited in-vivo tumorigenesis, and maintained their EMT and epithelial nature in-vivo in mice tumors. Notably, while both cell types exhibited increase in tumor-initiating cell population, differential EMT phenotype was observed in these cell lines. These results suggest that EMT is a cell type dependent

Disturbed secretion of mutant adiponectin associated with the metabolic syndrome.

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Kishida, Ken; Nagaretani, Hiroyuki; Kondo, Hidehiko; Kobayashi, Hideki; Tanaka, Sachiyo; Maeda, Norikazu; Nagasawa, Azumi; Hibuse, Toshiyuki; Ohashi, Koji; Kumada, Masahiro; Nishizawa, Hitoshi; Okamoto, Yoshihisa; Ouchi, Noriyuki; Maeda, Kazuhisa; Kihara, Shinji; Funahashi, Tohru; Matsuzawa, Yuji

2003-06-20

Adiponectin, an adipocyte-derived protein, consists of collagen-like fibrous and complement C1q-like globular domains, and circulates in human plasma in a multimeric form. The protein exhibits anti-diabetic and anti-atherogenic activities. However, adiponectin plasma concentrations are low in obese subjects, and hypoadiponectinemia is associated with the metabolic syndrome, which is a cluster of insulin resistance, type 2 diabetes mellitus, hypertension, and dyslipidemia. We have recently reported a missense mutation in the adiponectin gene, in which isoleucine at position 164 in the globular domain is substituted with threonine (I164T). Subjects with this mutation showed markedly low level of plasma adiponectin and clinical features of the metabolic syndrome. Here, we examined the molecular characteristics of the mutant protein associated with a genetic cause of hypoadiponectinemia. The current study revealed (1) the mutant protein showed an oligomerization state similar to the wild-type as determined by gel filtration chromatography and, (2) the mutant protein exhibited normal insulin-sensitizing activity, but (3) pulse-chase study showed abnormal secretion of the mutant protein from adipose tissues. Our results suggest that I164T mutation is associated with hypoadiponectinemia through disturbed secretion into plasma, which may contribute to the development of the metabolic syndrome.

Diminished self-chaperoning activity of the DeltaF508 mutant of CFTR results in protein misfolding.

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Adrian W R Serohijos

2008-02-01

Full Text Available The absence of a functional ATP Binding Cassette (ABC protein called the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR from apical membranes of epithelial cells is responsible for cystic fibrosis (CF. Over 90% of CF patients carry at least one mutant allele with deletion of phenylalanine at position 508 located in the N-terminal nucleotide binding domain (NBD1. Biochemical and cell biological studies show that the DeltaF508 mutant exhibits inefficient biosynthetic maturation and susceptibility to degradation probably due to misfolding of NBD1 and the resultant misassembly of other domains. However, little is known about the direct effect of the Phe508 deletion on the NBD1 folding, which is essential for rational design strategies of cystic fibrosis treatment. Here we show that the deletion of Phe508 alters the folding dynamics and kinetics of NBD1, thus possibly affecting the assembly of the complete CFTR. Using molecular dynamics simulations, we find that meta-stable intermediate states appearing on wild type and mutant folding pathways are populated differently and that their kinetic accessibilities are distinct. The structural basis of the increased misfolding propensity of the DeltaF508 NBD1 mutant is the perturbation of interactions in residue pairs Q493/P574 and F575/F578 found in loop S7-H6. As a proof-of-principle that the S7-H6 loop conformation can modulate the folding kinetics of NBD1, we virtually design rescue mutations in the identified critical interactions to force the S7-H6 loop into the wild type conformation. Two redesigned NBD1-DeltaF508 variants exhibited significantly higher folding probabilities than the original NBD1-DeltaF508, thereby partially rescuing folding ability of the NBD1-DeltaF508 mutant. We propose that these observed defects in folding kinetics of mutant NBD1 may also be modulated by structures separate from the 508 site. The identified structural determinants of increased misfolding propensity of

A genetic screen for increasing metabolic flux in the isoprenoid pathway of Saccharomyces cerevisiae: Isolation of SPT15 mutants using the screen

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M. Wadhwa

2016-12-01

Full Text Available A genetic screen to identify mutants that can increase flux in the isoprenoid pathway of yeast has been lacking. We describe a carotenoid-based visual screen built with the core carotenogenic enzymes from the red yeast Rhodosporidium toruloides. Enzymes from this yeast displayed the required, higher capacity in the carotenoid pathway. The development also included the identification of the metabolic bottlenecks, primarily phytoene dehydrogenase, that was subjected to a directed evolution strategy to yield more active mutants. To further limit phytoene pools, a less efficient version of GGPP synthase was employed. The screen was validated with a known flux increasing gene, tHMG1. New mutants in the TATA binding protein SPT15 were isolated using this screen that increased the yield of carotenoids, and an alternate isoprenoid, α-Farnesene confirming increase in overall flux. The findings indicate the presence of previously unknown links to the isoprenoid pathway that can be uncovered using this screen. Keywords: Metabolic engineering, Carotenoids, Isoprenoids, α-Farnesene, Rhodosporidium toruloides, SPT15

A yeast mutant specifically sensitive to bifunctional alkylation

International Nuclear Information System (INIS)

Ruhland, A.; Kircher, M.; Wilborn, F.; Brendel, M.

1981-01-01

A mutation that specifically confers sensitivity to bi- and tri-functional alkylating agents is presented. No or little cross-sensitivity to radiation or monofunctional agents could be detected. Sensitivity does not seem to be due to preferential alkylation of mutant DNA as parent and mutant strain exhibit the same amount of DNA alkylation and the same pattern of DNA lesions including interstrand crosslinks. The mutation is due to a defect in a nuclear gene which has been designated SNM1 (sensitive to nitrogen mustard); it may control an important step in the repair of DNA interstrand crosslinks (orig.(AJ)

Mutant strains of Spirulina (Arthrospira) platensis to increase the efficiency of micro-ecological life support systems

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Brown, Igor

The European Micro-Ecological Life Support System Alternative (MELiSSA) is an advanced idea for organizing a bioregenerative system for long term space flights and extraterrestrial settlements (Hendrickx, De Wever et al., 2005). Despite the hostility of both lunar and Martian environments to unprotected life, it seems possible to cultivate photosynthetic bacteria using closed bioreactors illuminated and heated by solar energy. Such reactors might be employed in critical processes, e.g. air revitalization, foodcaloric and protein source, as well as an immunomodulators production. The MELiSSA team suggested cyanobacterium Spirulina as most appropriate agent to revitalize air and produce a simple "fast" food. This is right suggestion because Spirulina was recently shown to be an oxygenic organism with the highest level of O2 production per unit mass (Ananyev et al., 2005). Chemical composition of Spirulina includes proteins (55Aiming to make Spirulina cultivation in life support systems like MELiSSA more efficient, we selected Spirulina mutant strains with increased fraction of methionine in the biomass of this cyanobacterium and compared the effect of parental wild strain of Spirulina and its mutants on the tendency of such experimental illnesses as radiationinduced lesions and hemolythic anemia. Results: It was found that mutant strains 198B and 27G contain higher quantities of total protein, essential amino acids, c-phycocyanin, allophycocyanin and chlorophyll a than parental wild strain of S. platensis. The strain 198B is also characterized with increased content of carotenoids. Revealed biochemical peculiarities of mutant strains suggest that these strains can serve as an additional source of essential amino acids as well as phycobiliproteins and carotenoids for the astronauts. Feeding animals suffering from radiation-induced lesions, c-phycocyanin, extracted from strain 27G, led to a correction in deficient dehydrogenase activity and energy-rich phosphate levels

Soya bean Gα proteins with distinct biochemical properties exhibit differential ability to complement Saccharomyces cerevisiae gpa1 mutant.

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Roy Choudhury, Swarup; Wang, Yuqi; Pandey, Sona

2014-07-01

Signalling pathways mediated by heterotrimeric G-proteins are common to all eukaryotes. Plants have a limited number of each of the G-protein subunits, with the most elaborate G-protein network discovered so far in soya bean (Glycine max, also known as soybean) which has four Gα, four Gβ and ten Gγ proteins. Biochemical characterization of Gα proteins from plants suggests significant variation in their properties compared with the well-characterized non-plant proteins. Furthermore, the four soya bean Gα (GmGα) proteins exhibit distinct biochemical activities among themselves, but the extent to which such biochemical differences contribute to their in vivo function is also not known. We used the yeast gpa1 mutant which displays constitutive signalling and growth arrest in the pheromone-response pathway as an in vivo model to evaluate the effect of distinct biochemical activities of GmGα proteins. We showed that specific GmGα proteins can be activated during pheromone-dependent receptor-mediated signalling in yeast and they display different strengths towards complementation of yeast gpa1 phenotypes. We also identified amino acids that are responsible for differential complementation abilities of specific Gα proteins. These data establish that specific plant Gα proteins are functional in the receptor-mediated pheromone-response pathway in yeast and that the subtle biochemical differences in their activity are physiologically relevant.

Ibrutinib targets mutant-EGFR kinase with a distinct binding conformation.

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Wang, Aoli; Yan, Xiao-E; Wu, Hong; Wang, Wenchao; Hu, Chen; Chen, Cheng; Zhao, Zheng; Zhao, Peng; Li, Xixiang; Wang, Li; Wang, Beilei; Ye, Zi; Wang, Jinhua; Wang, Chu; Zhang, Wei; Gray, Nathanael S; Weisberg, Ellen L; Chen, Liang; Liu, Jing; Yun, Cai-Hong; Liu, Qingsong

2016-10-25

Ibrutinib, a clinically approved irreversible BTK kinase inhibitor for Mantle Cell Lymphoma (MCL) and Chronic Lymphocytic Leukemia (CLL) etc, has been reported to be potent against EGFR mutant kinase and currently being evaluated in clinic for Non Small Cell Lung Cancer (NSCLC). Through EGFR wt/mutant engineered isogenic BaF3 cell lines we confirmed the irreversible binding mode of Ibrutinib with EGFR wt/mutant kinase via Cys797. However, comparing to typical irreversible EGFR inhibitor, such as WZ4002, the washing-out experiments revealed a much less efficient covalent binding for Ibrutinib. The biochemical binding affinity examination in the EGFR L858R/T790M kinase revealed that, comparing to more efficient irreversible inhibitor WZ4002 (Kd: 0.074 μM), Ibrutinib exhibited less efficient binding (Kd: 0.18 μM). An X-ray crystal structure of EGFR (T790M) in complex with Ibrutinib exhibited a unique DFG-in/c-Helix-out inactive binding conformation, which partially explained the less efficiency of covalent binding and provided insight for further development of highly efficient irreversible binding inhibitor for the EGFR mutant kinase. These results also imply that, unlike the canonical irreversible inhibitor, sustained effective concentration might be required for Ibrutinib in order to achieve the maximal efficacy in the clinic application against EGFR driven NSCLC.

Sharing mutants and experimental information prepublication using FgMutantDb (https://scabusa.org/FgMutantDb).

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Baldwin, Thomas T; Basenko, Evelina; Harb, Omar; Brown, Neil A; Urban, Martin; Hammond-Kosack, Kim E; Bregitzer, Phil P

2018-06-01

There is no comprehensive storage for generated mutants of Fusarium graminearum or data associated with these mutants. Instead, researchers relied on several independent and non-integrated databases. FgMutantDb was designed as a simple spreadsheet that is accessible globally on the web that will function as a centralized source of information on F. graminearum mutants. FgMutantDb aids in the maintenance and sharing of mutants within a research community. It will serve also as a platform for disseminating prepublication results as well as negative results that often go unreported. Additionally, the highly curated information on mutants in FgMutantDb will be shared with other databases (FungiDB, Ensembl, PhytoPath, and PHI-base) through updating reports. Here we describe the creation and potential usefulness of FgMutantDb to the F. graminearum research community, and provide a tutorial on its use. This type of database could be easily emulated for other fungal species. Published by Elsevier Inc.

The novel mouse mutant, chuzhoi, has disruption of Ptk7 protein and exhibits defects in neural tube, heart and lung development and abnormal planar cell polarity in the ear

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Paudyal Anju

2010-08-01

Full Text Available Abstract Background The planar cell polarity (PCP signalling pathway is fundamental to a number of key developmental events, including initiation of neural tube closure. Disruption of the PCP pathway causes the severe neural tube defect of craniorachischisis, in which almost the entire brain and spinal cord fails to close. Identification of mouse mutants with craniorachischisis has proven a powerful way of identifying molecules that are components or regulators of the PCP pathway. In addition, identification of an allelic series of mutants, including hypomorphs and neomorphs in addition to complete nulls, can provide novel genetic tools to help elucidate the function of the PCP proteins. Results We report the identification of a new N-ethyl-N-nitrosourea (ENU-induced mutant with craniorachischisis, which we have named chuzhoi (chz. We demonstrate that chuzhoi mutant embryos fail to undergo initiation of neural tube closure, and have characteristics consistent with defective convergent extension. These characteristics include a broadened midline and reduced rate of increase of their length-to-width ratio. In addition, we demonstrate disruption in the orientation of outer hair cells in the inner ear, and defects in heart and lung development in chuzhoi mutants. We demonstrate a genetic interaction between chuzhoi mutants and both Vangl2Lp and Celsr1Crsh mutants, strengthening the hypothesis that chuzhoi is involved in regulating the PCP pathway. We demonstrate that chuzhoi maps to Chromosome 17 and carries a splice site mutation in Ptk7. This mutation results in the insertion of three amino acids into the Ptk7 protein and causes disruption of Ptk7 protein expression in chuzhoi mutants. Conclusions The chuzhoi mutant provides an additional genetic resource to help investigate the developmental basis of several congenital abnormalities including neural tube, heart and lung defects and their relationship to disruption of PCP. The chuzhoi mutation

Integrative Genomic Analysis of Cholangiocarcinoma Identifies Distinct IDH-Mutant Molecular Profiles

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Farshad Farshidfar

2017-03-01

Full Text Available Cholangiocarcinoma (CCA is an aggressive malignancy of the bile ducts, with poor prognosis and limited treatment options. Here, we describe the integrated analysis of somatic mutations, RNA expression, copy number, and DNA methylation by The Cancer Genome Atlas of a set of predominantly intrahepatic CCA cases and propose a molecular classification scheme. We identified an IDH mutant-enriched subtype with distinct molecular features including low expression of chromatin modifiers, elevated expression of mitochondrial genes, and increased mitochondrial DNA copy number. Leveraging the multi-platform data, we observed that ARID1A exhibited DNA hypermethylation and decreased expression in the IDH mutant subtype. More broadly, we found that IDH mutations are associated with an expanded histological spectrum of liver tumors with molecular features that stratify with CCA. Our studies reveal insights into the molecular pathogenesis and heterogeneity of cholangiocarcinoma and provide classification information of potential therapeutic significance.

Increased somatic cell mutant frequency in atomic bomb survivors

International Nuclear Information System (INIS)

Hakoda, Masayuki; Akiyama, Mitoshi; Kyoizumi, Seishi; Awa, A.A.; Yamakido, Michio; Otake, Masanori.

1988-05-01

Frequencies of mutant T-cells in peripheral blood, which are deficient in the activity of hypoxanthine guanine phosphoribosyltransferase (HPRT) were determined for atomic bomb survivors by direct clonal assay using a previously reported method. Results from 30 exposed survivors (exposed to more than 1 rad) and 17 age- and sex-matched controls (exposed to less than 1 rad) were analyzed. The mean mutant frequency (Mf) in the exposed (5.2 x 10 -6 ; range 0.8 - 14.4 x 10 -6 ) was significantly higher than in controls (3.4 x 10 -6 ; range 1.3 - 9.3 x 10 -6 ), a fact not attributable to lower nonmutant cell cloning efficiencies in the exposed group since cell cloning efficiencies were virtually identical in both groups. An initial analysis of the data did not reveal a significant correlation between individual Mfs and individual radiation dose estimates when the latter were defined by the original, tentative estimates (T65D), even though there was a significant positive correlation of Mfs with individual frequency of lymphocytes bearing chromosome aberration. However, reanalysis using the newer revised individual dose estimates (DS86) for 27 exposed survivors and 17 controls did reveal a significant but shallow positive correlation between T-cell Mf values and individual exposure doses. These results indicate that HPRT mutation in vivo in human T-cells could be detected in these survivors 40 years after the presumed mutational event. (author)

Combined exposure of ELF magnetic fields and X-rays increased mutant yields compared with X-rays alone in pTN89 plasmids

International Nuclear Information System (INIS)

Koyama, Shin; Nakahara, Takehisa; Sakurai, Tomonori; Komatsubara, Yoshiki; Miyakoshi, Junji; Isozumi, Yasuhito

2005-01-01

We have examined mutations in the supF gene carried by pTN89 plasmids in Escherichia coli (E. coli) to examine the effects of extremely low frequency magnetic fields (ELFMFs) and/or X-rays to the plasmids. The plasmids were subjected to sham exposure or exposed to an ELFMF (5 mT), with or without X-ray irradiation (10 Gy). For the combined treatments, exposure to the ELFMF was immediately before or after X-ray irradiation. The mutant fractions were 0.94 x 10 -5 for X-rays alone, 1.58 x 10 -5 for an ELFMF followed by X-rays, and 3.64 x 10 -5 for X-rays followed by an ELFMF. Increased mutant fraction was not detected following exposure to a magnetic field alone, or after sham exposure. The mutant fraction for X-rays followed by an ELFMF was significantly higher than those of other treatments. Sequence analysis of the supF mutant plasmids revealed that base substitutions were dominant on exposure to X-rays alone and X-rays plus an ELFMF. Several types of deletions were detected in only the combined treatments, but not with X-rays alone. We could not find any mutant colonies in sham irradiated and an ELFMF alone treatment, but exposure to ELFMFs immediately before or after X-ray irradiation may enhance the mutations. Our results indicate that an ELFMF increases mutation and alters the spectrum of mutations. (author)

Uvm mutants of Escherichia coli K 12 deficient in UV mutagenesis. Pt. 1

International Nuclear Information System (INIS)

Steinborn, G.

1978-01-01

Selection for defective reversion induction, after UV treatment of E. coli K 12, yielded uvm mutants. These mutants exhibited highly reduced or no UV mutability for all loci tested although they were moderately and normally mutable by X-rays and EMS, respectively. Uvm mutations confer only a slight sensitivity to killing by UV and X-rays and no clear sensitivity to the lethal effect of HN2, EMS or MMS. Growth and viability of untreated uvm cells were normal. The properties of uvm mutants are discussed in relation to those of other relevant mutant types and to some actual problems of induced mutagenesis. (orig.) 891 AJ [de

Gamma ray induced mutants in Coleus

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Vasudevan, K; Jos, J S [Central Tuber Crops Research Institute, Trivandrum, Kerala (India)

1988-07-01

The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M{sub 1}V{sub 1} generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m{sup 2} area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing.

Gamma ray induced mutants in Coleus

International Nuclear Information System (INIS)

Vasudevan, K.; Jos, J.S.

1988-01-01

The germplasm collection of Chinese potato (Coleus parviflorus Benth) contains almost no variation for yield contributing traits. The crop does not produce seeds. Treatment of underground tubers with 1 kR, 2 kR, 3 kR and 4 kR gamma rays resulted in 50 morphologically different mutants which are maintained as mutant clones. In the M 1 V 1 generation, suspected mutant sprouts, were carefully removed and grown separately. The most interesting mutant types are the following: (i) erect mutant with spoon shaped light green leaves, 30 cm long inflorescences against 20 cm in the control, cylindrical tubers measuring ca. 7.0 cm long and 3 cm girth against 4 cm and 2.5 cm in the control (ii) early mutants 1 and 2, one having less leaf serration, the other having light green small leaves and dwarf type (iii) fleshy leaf mutant, dark green, thick and smooth leaves. Control plants spread almost in 1 m 2 area and bear tubers from the nodes of branches. In the early mutants tuber formation is mainly restricted to the base of the plant, which makes harvest easier. The crop usually matures within 150 - 160 days, the early mutants are ready for harvest 100 days after planting. As the mutants are less spreading, the yield could be increased by closer spacing

Induced mutants of Cox's Orange Pippin apple with apparent increased self-compatibility. Pt. 2

International Nuclear Information System (INIS)

Church, R.M.; Lacey, C.N.D.; Richardson, P.

1982-01-01

Fruit set on clones of Cox's Orange Pippin apple which had been produced by gamma-irradiation, and found in a previous trial to crop when isolated from the pollen of other cultivars, was compared after open or hand-pollination. Some clones set more fruit than the unirradiated control trees when open pollinated or when hand-pollinated with pollen from the same tree or control Cox trees. Pollen from some mutant clones also improved set on standard Cox (EMLA). Estimates of the numbers of pollen tubes reaching the base of the style indicated that the increased set was due to enhanced tube growth. (orig.)

Genetics of leaf rust-resistant mutant WH 147-LM-1 in hexaploid wheat variety WH 147

International Nuclear Information System (INIS)

Reddy, V.R.K.; Viswanathan, P.

1999-01-01

By applying gamma rays, EMS and their combination in hexaploid wheat variety WH 147, a total of 20 mutants (0.0226%) exhibiting complete leaf rust resistance were isolated from segregating M2 rows.When one of the rust-resistant mutants, WH 147-LM-1 was crossed with the universally susceptible, suggesting that the mutant character is controlled by one dominant gene and one recessive gene.The F2 plants derived by crossing the mutant WH 147-LM with seven near-isogenic wheat lines showed segregation for susceptibility, indicating that the mutant character was indeed generated through induced mutations

DNA binding properties of dioxin receptors in wild-type and mutant mouse hepatoma cells

International Nuclear Information System (INIS)

Cuthill, S.; Poellinger, L.

1988-01-01

The current model of action of 2,3,7,8-tetrachlorodibenzo-p-dioxin (dioxin) entails stimulation of target gene transcription via the formation of dioxin-receptor complexes and subsequent accumulation of the complexes within the cell nucleus. Here, the authors have analyzed the DNA binding properties of the dioxin receptor in wild-type mouse hepatoma (Hepa 1c1c7) cells and a class of nonresponsive mutant cells which fail to accumulate dioxin-receptor complexes within the nucleus in vivo. In vitro, both the wild-type and mutant [ 3 H]dioxin-receptor complexes exhibited low affinity for DNA-cellulose (5-8% and around 4% retention, respectively) in the absence of prior biochemical manipulations. However, following chromatography on heparin-Sepharose, the wild-type but not the mutant dioxin receptor was transformed to a species with an increased affinity for DNA (40-50% retention on DNA-cellulose). The gross molecular structure of the mutant, non DNA binding dioxin receptor did not appear to be altered as compared to that of the wild-type receptor. These results imply that the primary deficiency in the mutant dioxin receptor form may reside at the DNA binding level and that, in analogy to steroid hormone receptors, DNA binding of the receptor may be an essential step in the regulation of target gene transcription by dioxin

Genetical, cytological and physiological studies on the induced mutants with special regard to effective methods for obtaining useful mutants in perennial woody plants

International Nuclear Information System (INIS)

Kukimura, H.; Ikeda, F.; Fujita, H.; Maeta, T.; Nakajima, K.; Katagiri, K.; Nakahira, K.; Somegou, M.

1975-01-01

The study was aimed at elucidating the biological aspects of artificially induced mutations in perennial tree crops and at promoting the utilization of such mutations in a practical breeding programme. A number of mutants obtained particularly in Cryptomeria and mulberry (Morus spp.) by means of gamma radiation were examined for their practical usefulness. Doses from 7.5 to 15.0 kR were used. In mulbery, some mutant strains showed increased shoot growth, and one mutant strain showed a remarkable increase also in rooting ability. Entire leaf mutants were investigated for their breeding behaviour. None of the mutant strains showed acquired disease resistance. Changes in the number of isozyme bands and different staining intensity was observed in all the mutant strains compared to the original strains

Abnormal grooming activity in Dab1(scm) (scrambler) mutant mice.

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Strazielle, C; Lefevre, A; Jacquelin, C; Lalonde, R

2012-07-15

Dab1(scm) mutant mice, characterized by cell ectopias and degeneration in cerebellum, hippocampus, and neocortex, were compared to non-ataxic controls for different facets of grooming caused by brief water immersions, as well as some non-grooming behaviors. Dab1(scm) mutants were strongly affected in their quantitative functional parameters, exhibiting higher starting latencies before grooming relative to non-ataxic littermates of the A/A strain, fewer grooming bouts, and grooming components of shorter duration, with an unequal regional distribution targeting almost totally the rostral part (head washing and forelimb licking) of the animal. Only bouts of a single grooming element were preserved. The cephalocaudal order of grooming elements appeared less disorganized, mutant and control mice initiating the grooming with head washing and forelimb licking prior to licking posterior parts. However, mutants differed from controls in that all their bouts were incomplete but uninterrupted, although intergroup difference for percentage of the incorrect transitions was not significant. In contrast to grooming, Dab1(scm) mice ambulated for a longer time. During walking episodes, they exhibited more body scratching than controls, possibly to compensate for the lack of licking different body parts. In conjunction with studies with other ataxic mice, these results indicate that the cerebellar cortex affects grooming activity and is consequently involved in executing various components, but not in its sequential organization, which requires other brain regions such as cerebral cortices or basal ganglia. Copyright © 2012 Elsevier B.V. All rights reserved.

Connexin mutants and cataracts

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Eric C Beyer

2013-04-01

Full Text Available The lens is a multicellular, but avascular tissue that must stay transparent to allow normal transmission of light and focusing of it on the retina. Damage to lens cells and/or proteins can cause cataracts, opacities that disrupt these processes. The normal survival of the lens is facilitated by an extensive network of gap junctions formed predominantly of connexin46 and connexin50. Mutations of the genes that encode these connexins (GJA3 and GJA8 have been identified and linked to inheritance of cataracts in human families and mouse lines. In vitro expression studies of several of these mutants have shown that they exhibit abnormalities that may lead to disease. Many of the mutants reduce or modify intercellular communication due to channel alterations (including loss of function or altered gating or due to impaired cellular trafficking which reduces the number of gap junction channels within the plasma membrane. However, the abnormalities detected in studies of other mutants suggest that they cause cataracts through other mechanisms including gain of hemichannel function (leading to cell injury and death and formation of cytoplasmic accumulations (that may act as light scattering particles. These observations and the anticipated results of ongoing studies should elucidate the mechanisms of cataract development due to mutations of lens connexins and abnormalities of other lens proteins. They may also contribute to our understanding of the mechanisms of disease due to connexin mutations in other tissues.

PNRI mutant variety: Cordyline 'Afable'

International Nuclear Information System (INIS)

Aurigue, Fernando B.

2012-01-01

Cordyline 'Afable', registered by the Philippine Nuclear Research Institute as NSIC 2009 Or-83, is an induced mutant developed from Cordyline 'Kiwi' by treating stem cuttings with acute gamma radiation from a Cobalt-60 source. The new mutant is identical to Cordyline 'Kiwi' in growth habit but differs in foliage color, and exhibits field resistance to Phytophthora sp., a fungus that causes leaf blight and rot in Ti plants. Results of this mutation breeding experiment showed that leaf color was altered by gamma irradiation and resistance to fungal diseases was improved. It also demonstrated how mutations that occur in nature may be generated artificially. Propagation of cordyline 'Afable' is true-to-type by vegetative propagation methods, such as separation of suckers and offshoots, shoot tip cutting, and top cutting. Aside from landscaping material, terrarium or dish-garden plant, it is ideal as containerized plant for indoor and outdoor use. The leaves or shoots may be harvested as cut foliage for flower arrangements. (author)

Absence-like and tonic seizures in aspartoacylase/attractin double-mutant mice.

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Gohma, Hiroshi; Kuramoto, Takashi; Matalon, Reuben; Surendran, Sankar; Tyring, Stephen; Kitada, Kazuhiro; Sasa, Masashi; Serikawa, Tadao

2007-04-01

The Spontaneously Epileptic Rat (SER), a double-mutant for tremor and zitter mutations, shows spontaneous occurrences of absence-like and tonic seizures. Several lines of evidence suggest that the combined effect of Aspa and Atrn mutations is the most likely cause of the epileptic phenotype of the SER. To address this issue, we produced a new double-mutant mouse line carrying both homozygous Aspa-knockout and Atrn(mg-3J) mutant alleles. The Aspa/Atrn double-mutant mice exhibited absence-like and tonic seizures that were characterized by the appearance of 5-7 Hz spike-wave-like complexes and low voltage fast waves on EEGs. These results demonstrate directly that the simultaneous loss of the Aspa and Atrn gene functions causes epileptic seizures in the mouse and suggest that both Aspa and Atrn deficiencies might be responsible for epileptic seizures in the SER.

Serine:glyoxylate aminotransferase mutant of barley

International Nuclear Information System (INIS)

Blackwell, R.; Murray, A.; Joy, K.; Lea, P.

1987-01-01

A photorespiratory mutant of barley (LaPr 85/84), deficient in both of the major peaks of serine:glyoxylate aminotransferase activity detected in the wild type, also lacks serine:pyruvate and asparagine:glyoxylate aminotransferase activities. Genetic analysis of the mutation demonstrated that these three activities are all carried on the same enzyme. The mutant, when placed in air, accumulated a large pool of serine, showed the expected rate (50%) of ammonia release during photorespiration but produced CO 2 at twice the wild type rate when it was fed [ 14 C] glyoxylate. Compared with the wild type, LaPr 85/84 exhibited abnormal transient changes in chlorophyll a fluorescence when the CO 2 concentration of the air was altered, indicating that the rates of the fluorescence quenching mechanisms were affected in vivo by the lack of this enzyme

Defective glycinergic synaptic transmission in zebrafish motility mutants

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Hiromi Hirata

2010-01-01

Full Text Available Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR β subunit genes. These mutants exhibit a loss of glycinergic synaptic transmission due to a lack of synaptic aggregation of GlyRs. Due to the consequent loss of reciprocal inhibition of motor circuits between the two sides of the spinal cord, motor neurons activate simultaneously on both sides resulting in bilateral contraction of axial muscles of beo mutants, eliciting the so-called ‘accordion’ phenotype. Similar defects in GlyR subunit genes have been observed in several mammals and are the basis for human hyperekplexia/startle disease. By contrast, zebrafish shocked (sho mutants have a defect in slc6a9, encoding GlyT1, a glycine transporter that is expressed by astroglial cells surrounding the glycinergic synapse in the hindbrain and spinal cord. GlyT1 mediates rapid uptake of glycine from the synaptic cleft, terminating synaptic transmission. In zebrafish sho mutants, there appears to be elevated extracellular glycine resulting in persistent inhibition of postsynaptic neurons and subsequent reduced motility, causing the ‘twitch once’ phenotype. We review current knowledge regarding zebrafish ‘accordion’ and ‘twitch once’ mutants, including beo and sho, and report the identification of a new α2 subunit that revises the phylogeny of zebrafish GlyRs.

Defective Glycinergic Synaptic Transmission in Zebrafish Motility Mutants

Science.gov (United States)

Hirata, Hiromi; Carta, Eloisa; Yamanaka, Iori; Harvey, Robert J.; Kuwada, John Y.

2009-01-01

Glycine is a major inhibitory neurotransmitter in the spinal cord and brainstem. Recently, in vivo analysis of glycinergic synaptic transmission has been pursued in zebrafish using molecular genetics. An ENU mutagenesis screen identified two behavioral mutants that are defective in glycinergic synaptic transmission. Zebrafish bandoneon (beo) mutants have a defect in glrbb, one of the duplicated glycine receptor (GlyR) β subunit genes. These mutants exhibit a loss of glycinergic synaptic transmission due to a lack of synaptic aggregation of GlyRs. Due to the consequent loss of reciprocal inhibition of motor circuits between the two sides of the spinal cord, motor neurons activate simultaneously on both sides resulting in bilateral contraction of axial muscles of beo mutants, eliciting the so-called ‘accordion’ phenotype. Similar defects in GlyR subunit genes have been observed in several mammals and are the basis for human hyperekplexia/startle disease. By contrast, zebrafish shocked (sho) mutants have a defect in slc6a9, encoding GlyT1, a glycine transporter that is expressed by astroglial cells surrounding the glycinergic synapse in the hindbrain and spinal cord. GlyT1 mediates rapid uptake of glycine from the synaptic cleft, terminating synaptic transmission. In zebrafish sho mutants, there appears to be elevated extracellular glycine resulting in persistent inhibition of postsynaptic neurons and subsequent reduced motility, causing the ‘twitch-once’ phenotype. We review current knowledge regarding zebrafish ‘accordion’ and ‘twitch-once’ mutants, including beo and sho, and report the identification of a new α2 subunit that revises the phylogeny of zebrafish GlyRs. PMID:20161699

Mutants induced in winter rye (Secale cereale L.): Short straw-mutant No. 2714 and late-senescence mutant

Energy Technology Data Exchange (ETDEWEB)

Muszynski, S; Darlewska, M [Department of Plant Breeding and Seed Science, Warsaw Agricultural University, Warsaw (Poland)

1990-01-01

Full text: Mutants were induced by treating dormant seeds with ionizing radiation (fast neutrons) or chemicals (N-nitroso-N-ethyl urea or sodium azide). Among several mutants obtained, of special value is the short-straw mutant No. 2714 and a late senescent mutant. (author)

Generation and characterization of pigment mutants of ...

African Journals Online (AJOL)

Compared to the wild CC-124, these mutants are characterized by a decrease in chlorophyll a & b content and an increase in carotenoids. The lowest decrease in chlorophyll a was 3 to 4 folds, while the highest increase in carotenoids was 2 to 4 folds. The result of bio-test, using the resulting pigment mutant of C. reinhardtii ...

Generation of a Mutant Mucor hiemalis Endoglycosidase That Acts on Core-fucosylated N-Glycans.

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Katoh, Toshihiko; Katayama, Takane; Tomabechi, Yusuke; Nishikawa, Yoshihide; Kumada, Jyunichi; Matsuzaki, Yuji; Yamamoto, Kenji

2016-10-28

Endo-β-N-acetylglucosaminidase M (Endo-M), an endoglycosidase from the fungus Mucor hiemalis, is a useful tool for chemoenzymatic synthesis of glycoconjugates, including glycoprotein-based therapeutics having a precisely defined glycoform, by virtue of its transglycosylation activity. Although Endo-M has been known to act on various N-glycans, it does not act on core-fucosylated N-glycans, which exist widely in mammalian glycoproteins, thus limiting its application. Therefore, we performed site-directed mutagenesis on Endo-M to isolate mutant enzymes that are able to act on mammalian-type core-α1,6-fucosylated glycans. Among the Endo-M mutant enzymes generated, those in which the tryptophan at position 251 was substituted with alanine or asparagine showed altered substrate specificities. Such mutant enzymes exhibited increased hydrolysis of a synthetic α1,6-fucosylated trimannosyl core structure, whereas their activity on the afucosylated form decreased. In addition, among the Trp-251 mutants, the W251N mutant was most efficient in hydrolyzing the core-fucosylated substrate. W251N mutants could act on the immunoglobulin G-derived core-fucosylated glycopeptides and human lactoferrin glycoproteins. This mutant was also capable of transferring the sialyl glycan from an activated substrate intermediate (sialyl glyco-oxazoline) onto an α1,6-fucosyl-N-acetylglucosaminyl biotin. Furthermore, the W251N mutant gained a glycosynthase-like activity when a N175Q substitution was introduced and it caused accumulation of the transglycosylation products. These findings not only give insights into the substrate recognition mechanism of glycoside hydrolase family 85 enzymes but also widen their scope of application in preparing homogeneous glycoforms of core-fucosylated glycoproteins for the production of potent glycoprotein-based therapeutics. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Bacillus subtilis mutants deficient in the adaptive response to simple alkylating agents

Energy Technology Data Exchange (ETDEWEB)

Morohoshi, F.; Munakata, N.

1985-03-01

Three mutant strains exhibiting hyper-sensitivity to N-methyl-N'-nitro-N-nitrosoguanidine, but not to methyl methanesulfonate, were selected by a replica method from mutagenized spores of Bacillus subtilis. All three were totally deficient in the adaptive response to N-methyl-N'-nitro-N-nitrosoguanidine with regard to both lethality and mutagenesis. The activity to destroy O/sup 6/-methylguanine residues in the methylated DNA was not elevated in the mutant cells by the pretreatment with sublethal concentrations of N-methyl-N-nitro-N-nitrosoguanidine. This deficiency corresponded to the persistance of O/sup 6/-methylguanine residues in the DNA of both control and pretreated mutant cells challenged with the drug. The lethal and mutagenic sensitivity of the mutant strains were observed only for methyl- or ethyl-nitroso compounds that are thought to be active as inducers and are also active in O-alkylation. Except for the insensitivity to methyl methanesulfonate, the phenotypes of these mutants look very similar to those of ada mutants isolated previously in Escherichia coli.

Ascertainment of the effect of differential growth rates of mutants on observed mutant frequencies in X-irradiated mammalian cells

International Nuclear Information System (INIS)

Knaap, A.G.A.C.; Simons, J.W.I.M.

1983-01-01

As it is not known to what extent differential growth rates of induced mutants lead to over- and under-representation of mutants in treated populations and thereby affect the determination of mutant frequencies, the mutation induction in X-irradiated L5178Y mouse lymphoma cells was determined via two methods. The first method involves the standard protocol which may suffer from the effect of differential growth rates, while the second method is based upon the fluctuation test in which the differential growth rates can be actually measured. It appeared that the standard protocol led to a mutant frequency that was similar to the mutant frequency determined in the fluctuation test. Therefore, the standard protocol appears to lead to only a minor under-estimation if any. Substantial heterogeneity in growth rates of induced mutants was observed, but the mutants with a selective advantage appear largely to compensate for the mutants that are lost because of selective disadvantage. It was calculated that the chance for isolating the same mutant twice from a treated population had been increased 2.2-fold because of the observed differential growth rates. (orig./AJ)

Determination quercetin content, antioxidant and antimicrobial activity of genotype mutant Samosir shallots irradiated by gamma rays

Science.gov (United States)

Sinuraya, M.; Hanafiah, D. S.; Romulo, A.; Barus, A.

2018-02-01

The aim of the research was to study the variation in antioxidant and antimicrobial activity as well as the total quercetin content of the fifth generation genotypes mutant Samosir shallot irradiated by gamma rays. The studies conducted included the assessment of quercetin content, antioxidant and antimicrobial activity in shallot bulbs after long-term storage (6 months in the room temperature). Quercetin content of 20 selected genotype mutants of irradiated shallot bulbs along with untreated populations were calculated using quercetin (QU) as a standard. Antioxidant activities of 8 genotype mutant were determined using DPPH. Antimicrobial activity of bulb extracts were tested against six bacteria including Staphylococcus aurous, Enterococcus faecalis, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae and oneyeastCandida albicans. The results showed that population of genotype mutants irradiated with dosage 2Gy, 4 Gy, 5 Gy and 6 Gy have higher quercetin content than control samples. None of the genotype mutants exhibited antibacterial inhibitory against all microorganism tested except for the sample number 2 and 6 (bulbs generated from the plants irradiated by gamma rays with dosage at 2 Gy and 6 Gy). There was also none of the genotypes observed exhibited significant antioxidant efficacy.

Mutants of Yarrowia lipolytica NCIM 3589 grown on waste cooking oil as a biofactory for biodiesel production.

Science.gov (United States)

Katre, Gouri; Ajmera, Namasvi; Zinjarde, Smita; RaviKumar, Ameeta

2017-10-24

higher heating values than the wild type strain. The chemical mutagenesis strategy adopted in this study resulted in the successful isolation of three stable high SCO yielding mutants. The mutants, namely, YlB6, YlC7 and YlE1 exhibited a 1.22, 1.33 and 1.49-fold increase in lipid contents when grown on 100 g L -1 waste cooking oil than the parental yeast strain. The fatty acid methyl ester (FAME) profiles of all the three mutants was determined to be suitable for biodiesel suggesting their potential applicability while simultaneously addressing the management of waste cooking oil.

Human liver cell trafficking mutants: characterization and whole exome sequencing.

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Fei Yuan

Full Text Available The HuH7 liver cell mutant Trf1 is defective in membrane trafficking and is complemented by the casein kinase 2α subunit CK2α''. Here we identify characteristic morphologies, trafficking and mutational changes in six additional HuH7 mutants Trf2-Trf7. Trf1 cells were previously shown to be severely defective in gap junction functions. Using a Lucifer yellow transfer assay, remarkable attenuation of gap junction communication was revealed in each of the mutants Trf2-Trf7. Electron microscopy and light microscopy of thiamine pyrophosphatase showed that several mutants exhibited fragmented Golgi apparatus cisternae compared to parental HuH7 cells. Intracellular trafficking was investigated using assays of transferrin endocytosis and recycling and VSV G secretion. Surface binding of transferrin was reduced in all six Trf2-Trf7 mutants, which generally correlated with the degree of reduced expression of the transferrin receptor at the cell surface. The mutants displayed the same transferrin influx rates as HuH7, and for efflux rate, only Trf6 differed, having a slower transferrin efflux rate than HuH7. The kinetics of VSV G transport along the exocytic pathway were altered in Trf2 and Trf5 mutants. Genetic changes unique to particular Trf mutants were identified by exome sequencing, and one was investigated in depth. The novel mutation Ile34Phe in the GTPase RAB22A was identified in Trf4. RNA interference knockdown of RAB22A or overexpression of RAB22AI34F in HuH7 cells caused phenotypic changes characteristic of the Trf4 mutant. In addition, the Ile34Phe mutation reduced both guanine nucleotide binding and hydrolysis activities of RAB22A. Thus, the RAB22A Ile34Phe mutation appears to contribute to the Trf4 mutant phenotype.

Metabolic analysis of the increased adventitious rooting mutant of Artemisia annua reveals a role for the plant monoterpene borneol in adventitious root formation.

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Tian, Na; Liu, Shuoqian; Li, Juan; Xu, Wenwen; Yuan, Lin; Huang, Jianan; Liu, Zhonghua

2014-08-01

Adventitious root (AR) formation is a critical process for plant clonal propagation. The role of plant secondary metabolites in AR formation is still poorly understood. Chemical and physical mutagenesis in combination with somatic variation were performed on Artemisia annua in order to obtain a mutant with changes in adventitious rooting and composition of plant secondary metabolites. Metabolic and morphological analyses of the iar (increased adventitious rooting) mutant coupled with in vitro assays were used to elucidate the relationship between plant secondary metabolites and AR formation. The only detected differences between the iar mutant and wild-type were rooting capacity and borneol/camphor content. Consistent with this, treatment with borneol in vitro promoted adventitious rooting in wild-type. The enhanced rooting did not continue upon removal of borneol. The iar mutant displayed no significant differences in AR formation upon treatment with camphor. Together, our results suggest that borneol promotes adventitious rooting whereas camphor has no effect on AR formation. © 2013 Scandinavian Plant Physiology Society.

Mutants of Escherichia coli K-12 with enhanced resistance to ionizing radiation. 4. Peculiarities of recombination in Gamsup(r) mutants

International Nuclear Information System (INIS)

Bresler, S.E.; Kalinin, V.L.; Laneeva, N.I.

1984-01-01

Radioresistant mutant Gam sup(r) 444 differs from a wild type and from Gam sup(r) 445 mutant in decreased frequency of long episome heritage ORF 1 (pur E + -tsx + -proC + -lac + ) and F 14 (ilv + -argE + ), containing hot points of RecRecF - depending recombination and in increased frequency of chromosome mobilization and integrative suppression of temperature sensitive dna A46 mutation by sexual factor F. In this respect Gam sup(r) 444 mutant resembles rec BC sbs B mutant with RecF - recombination type

Characterization of D-myo-inositol 3-phosphate synthase gene expression in two soybean low phytate mutants

International Nuclear Information System (INIS)

Yuan Fengjie; Dong Dekun; Li Baiquan; Yu Xiaomin; Fu Xujun; Zhu Danhua; Zhu Shenlong; Yang Qinghua

2013-01-01

1D-myo-inositol 3-phosphate synthase (MIPS) gene plays a significant role in phytic acid biosynthesis. In this study, we used two low phytic acid mutants Gm-lpa-TW-1, Gm-lpa-ZC-2 and their respective wild type parents Taiwan75 and Zhechun No.3 to analyze the expression pattern and characterization of MIPS1 gene. The results showed that there was a common expression pattern of MIPS1 in soybean developing seeds. Expression was weak as detected by RT-PCR in initial stage, increased in the following stages, and the peak expression was appeared in 22 day after flowering (DAF). The expression of MIPS1 gene of non-seed tissues in mutant Gm-lpa-TW-1 and its wildtype Taiwan75 was very weak. In the developing seeds, the MIPS1 expression by qRT-PCR revealed a significant reduction in 22 DAF in mutant Gm-lpa-TW-1 as compared with the wildtype. Similarly, the expression of MIPS1 gene in non-seed tissue of Zhenchun No.3 and Gm-lpa-ZC-2 was very weak. However, stronger expression in developing seeds of the mutant Gm-lpa-ZC-2 than Zhechun No.3 was found. We concluded that the MIPS1 gene expression in the developing seed exhibited an up-regulation pattern in mutant Gm-lpa-ZC-2, but a down-regulation pattern in the mutant Gm-lpa-TW-1. (authors)

Mutants of Aspergillus nidulans with increased resistance to the alkylating agent, N-methyl-N'-nitro-N-nitrosoguanidine.

Science.gov (United States)

Hooley, P; Shawcross, S G; Strike, P

1988-05-01

The isolation and characterisation of mutants of Aspergillus nidulans showing resistance to MNNG is described. Such isolates were stable through prolonged subculture in the absence of the selective agent, and resistance segregated as an allele of a single gene in meiotic and mitotic analysis. MNNG-resistant strains showed an increase in resistance to EMS and UV irradiation but no cross-resistance to MMS was detected. Possible mechanisms of resistance to alkylating agents are discussed.

Induction of two mutants in birdsfoot trefoil (Lotus corniculatus) by x-rays and chemical mutagens

International Nuclear Information System (INIS)

Therrien, M.C.; Grant, W.F.

1982-01-01

The mutagenic effects of X-rays, ethyl methanesulfonate (EMS), 8-ethoxycaffeine (EOC), N-hydroxyurea (HU) and 2-aminopurine (2AP) on seed treatment of birdsfoot trefoil (Lotus corniculatus L. 'Mirabel') were assessed over four generations. Mutants were recovered in the M 2 , M 3 and M 4 generations from selfed lines, from crosses derived form selfed lines and from open pollination lines. Mutant plants exhibiting vestigial floret character were recovered from X-rays, EMS, EOC and HU treatments. Mutant chlorotica plants were obtained from EMS treatment only. No mutants were recovered from 2AP treatment, EMS, the most effective mutagen, produced nine vestigial floret and 12 chlorotica mutants. Mutants were obtained from only one exposure of X-rays (12 krad). There was evidence for preferential elimination of gametes. The chlorotica and vestigial floret mutants were inherited as tetrasomic recessives. Mutation frequencies of 0.4 - 3.1% in a tetrasomic background are indicative of the effectiveness of EMS in birdsfoot trefoil

Induction of two mutants in birdsfoot trefoil (Lotus corniculatus) by x-rays and chemical mutagens

Energy Technology Data Exchange (ETDEWEB)

Therrien, M.C.; Grant, W.F. (McGill Univ., Ste. Anne de Bellevue, Quebec (Canada). Macdonald Coll.)

1982-10-01

The mutagenic effects of X-rays, ethyl methanesulfonate (EMS), 8-ethoxycaffeine (EOC), N-hydroxyurea (HU) and 2-aminopurine (2AP) on seed treatment of birdsfoot trefoil (Lotus corniculatus L. 'Mirabel') were assessed over four generations. Mutants were recovered in the M/sub 2/, M/sub 3/ and M/sub 4/ generations from selfed lines, from crosses derived form selfed lines and from open pollination lines. Mutant plants exhibiting vestigial floret character were recovered from X-rays, EMS, EOC and HU treatments. Mutant chlorotica plants were obtained from EMS treatment only. No mutants were recovered from 2AP treatment, EMS, the most effective mutagen, produced nine vestigial floret and 12 chlorotica mutants. Mutants were obtained from only one exposure of X-rays (12 krad). There was evidence for preferential elimination of gametes. The chlorotica and vestigial floret mutants were inherited as tetrasomic recessives. Mutation frequencies of 0.4 - 3.1% in a tetrasomic background are indicative of the effectiveness of EMS in birdsfoot trefoil.

Nonbehavioral Selection for Pawns, Mutants of PARAMECIUM AURELIA with Decreased Excitability

Science.gov (United States)

Schein, Stanley J.

1976-01-01

The reversal response in Paramecium aurelia is mediated by calcium which carries the inward current during excitation. Electrophysiological studies indicate that strontium and barium can also carry the inward current. Exposure to high concentrations of barium rapidly paralyzes and later kills wild-type paramecia. Following mutagenesis with nitrosoguanidine, seven mutants which continued to swim in the `high-barium' solution were selected. All of the mutants show decreased reversal behavior, with phenotypes ranging from extremely non-reversing (`extreme' pawns) to nearly wild-type reversal behavior (`partial' pawns). The mutations fall into three complementation groups, identical to the pwA, pwB, and pwC genes of Kung et al. (1975). All of the pwA and pwB mutants withstand longer exposure to barium, the pwB mutants surviving longer than the pwA mutants. Among mutants of each gene, survival is correlated with loss of reversal behavior. Double mutants (A–B, A–C, B–C), identified in the exautogamous progeny of crosses between `partial' mutants, exhibited a more extreme non-reversing phenotype than either of their single-mutant (`partial' pawn) parents.———Inability to reverse could be expected from an alteration in the calcium-activated reversal mechanism or in excitation. A normal calcium-activated structure was demonstrated in all pawns by chlorpromazine treatment. In a separate report (Schein, Bennett and Katz 1976) the results of electrophysiological investigations directly demonstrate decreased excitability in all of the mutants, a decrease due to an altered calcium activation. The studies of the genetics, the survival in barium and the electro-physiology of the pawns demonstrate that the pwA and pwB genes have different effects on calcium activation. PMID:1001878

'CM 88' - A multiple disease resistant chickpea mutant variety

International Nuclear Information System (INIS)

Haq, M.A.; Hassan, Mahmudul; Sadiq, M.

2001-01-01

Full text: Chickpea is the most important grain legume crop of Pakistan. Ascochyta blight (Ascochyta rabiei) and Fusarium wilt (Fusarium oxysporum F. sp cicer) are most serious diseases, having the potential to devastate a crop. A multiple disease resistant and high yielding mutant CM 88 has been developed through 100 Gy gamma irradiation treatment of variety 'C 727'. This was once a widely grown and popular variety, which lost its resistance to Ascochyta and was replaced. The selection of mutants was performed in the M2 generation grown in the Ascochyta blight nursery and sixteen mutants were selected. In the subsequent generations CM 88 proved resistant to both Ascochyta blight and Fusarium wilt, and exhibited superiority in agronomic characteristics. CM 88 was also tested for many years in the various yield trials on research stations and farmers fields throughout the country. In these trials it out yielded both the parent and standard varieties. The mutant CM 88 has been approved by the Punjab Seed Council on 27 October 1994 for general cultivation in the Punjab Province, especially the Thal area which accounts for more than 70% of the area under chickpea cultivation. (author)

Evolved osmotolerant Escherichia coli mutants frequently exhibit defective N-acetylglucosamine catabolism and point mutations in cell shape-regulating protein MreB.

Science.gov (United States)

Winkler, James D; Garcia, Carlos; Olson, Michelle; Callaway, Emily; Kao, Katy C

2014-06-01

Biocatalyst robustness toward stresses imposed during fermentation is important for efficient bio-based production. Osmotic stress, imposed by high osmolyte concentrations or dense populations, can significantly impact growth and productivity. In order to better understand the osmotic stress tolerance phenotype, we evolved sexual (capable of in situ DNA exchange) and asexual Escherichia coli strains under sodium chloride (NaCl) stress. All isolates had significantly improved growth under selection and could grow in up to 0.80 M (47 g/liter) NaCl, a concentration that completely inhibits the growth of the unevolved parental strains. Whole genome resequencing revealed frequent mutations in genes controlling N-acetylglucosamine catabolism (nagC, nagA), cell shape (mrdA, mreB), osmoprotectant uptake (proV), and motility (fimA). Possible epistatic interactions between nagC, nagA, fimA, and proV deletions were also detected when reconstructed as defined mutations. Biofilm formation under osmotic stress was found to be decreased in most mutant isolates, coupled with perturbations in indole secretion. Transcriptional analysis also revealed significant changes in ompACGL porin expression and increased transcription of sulfonate uptake systems in the evolved mutants. These findings expand our current knowledge of the osmotic stress phenotype and will be useful for the rational engineering of osmotic tolerance into industrial strains in the future. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Increased actin polymerization and stabilization interferes with neuronal function and survival in the AMPKγ mutant Loechrig.

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Mandy Cook

Full Text Available loechrig (loe mutant flies are characterized by progressive neuronal degeneration, behavioral deficits, and early death. The mutation is due to a P-element insertion in the gene for the γ-subunit of the trimeric AMP-activated protein kinase (AMPK complex, whereby the insertion affects only one of several alternative transcripts encoding a unique neuronal isoform. AMPK is a cellular energy sensor that regulates a plethora of signaling pathways, including cholesterol and isoprenoid synthesis via its downstream target hydroxy-methylglutaryl (HMG-CoA reductase. We recently showed that loe interferes with isoprenoid synthesis and increases the prenylation and thereby activation of RhoA. During development, RhoA plays an important role in neuronal outgrowth by activating a signaling cascade that regulates actin dynamics. Here we show that the effect of loe/AMPKγ on RhoA prenylation leads to a hyperactivation of this signaling pathway, causing increased phosphorylation of the actin depolymerizating factor cofilin and accumulation of filamentous actin. Furthermore, our results show that the resulting cytoskeletal changes in loe interfere with neuronal growth and disrupt axonal integrity. Surprisingly, these phenotypes were enhanced by expressing the Slingshot (SSH phosphatase, which during development promotes actin depolymerization by dephosphorylating cofilin. However, our studies suggest that in the adult SSH promotes actin polymerization, supporting in vitro studies using human SSH1 that suggested that SSH can also stabilize and bundle filamentous actin. Together with the observed increase in SSH levels in the loe mutant, our experiments suggest that in mature neurons SSH may function as a stabilization factor for filamentous actin instead of promoting actin depolymerization.

A mutation in the dynein heavy chain gene compensates for energy deficit of mutant SOD1 mice and increases potentially neuroprotective IGF-1

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Larmet Yves

2011-04-01

Full Text Available Abstract Background Amyotrophic lateral sclerosis (ALS is a fatal neurodegenerative disease characterized by a progressive loss of motor neurons. ALS patients, as well as animal models such as mice overexpressing mutant SOD1s, are characterized by increased energy expenditure. In mice, this hypermetabolism leads to energy deficit and precipitates motor neuron degeneration. Recent studies have shown that mutations in the gene encoding the dynein heavy chain protein are able to extend lifespan of mutant SOD1 mice. It remains unknown whether the protection offered by these dynein mutations relies on a compensation of energy metabolism defects. Results SOD1(G93A mice were crossbred with mice harboring the dynein mutant Cramping allele (Cra/+ mice. Dynein mutation increased adipose stores in compound transgenic mice through increasing carbohydrate oxidation and sparing lipids. Metabolic changes that occurred in double transgenic mice were accompanied by the normalization of the expression of key mRNAs in the white adipose tissue and liver. Furthermore, Dynein Cra mutation rescued decreased post-prandial plasma triglycerides and decreased non esterified fatty acids upon fasting. In SOD1(G93A mice, the dynein Cra mutation led to increased expression of IGF-1 in the liver, increased systemic IGF-1 and, most importantly, to increased spinal IGF-1 levels that are potentially neuroprotective. Conclusions These findings suggest that the protection against SOD1(G93A offered by the Cramping mutation in the dynein gene is, at least partially, mediated by a reversal in energy deficit and increased IGF-1 availability to motor neurons.

Comparative Study of Nonautolytic Mutant and Wild-Type Strains of Coprinopsis cinerea Supports an Important Role of Glucanases in Fruiting Body Autolysis.

Science.gov (United States)

Liu, Zhonghua; Niu, Xin; Wang, Jun; Zhang, Wenming; Yang, Mingmei; Liu, Cuicui; Xiong, Yuanjing; Zhao, Yan; Pei, Siyu; Qin, Qin; Zhang, Yu; Yu, Yuan; Yuan, Sheng

2015-11-04

Autolysis of Coprinopsis cinerea fruiting bodies affects its commercial value. In this study, a mutant of C. cinerea that exhibits pileus expansion without pileus autolysis was obtained using ultraviolet mutagenesis. This suggests that pileus expansion and pileus autolysis involve different enzymes or proteins. Among the detected hydrolytic enzymes, only β-1,3-glucanase activity increased with expansion and autolysis of pilei in the wild-type strain, but the increase was abolished in the mutant. This suggests that β-1,3-glucanases plays a major role in the autolysis. Although there are 43 possible β-1,3-glucoside hydrolases genes, only 4 known genes, which have products that are thought to act synergistically to degrade the β-1,3-glucan backbone of cell walls during fruiting body autolysis, and an unreported gene were upregulated during pileus expansion and autolysis in the wild-type stain but were suppressed in the mutant. This suggests that expression of these β-1,3-glucanases is potentially controlled by a single regulatory mechanism.

Rapid identification of lettuce seed germination mutants by bulked segregant analysis and whole genome sequencing.

Science.gov (United States)

Huo, Heqiang; Henry, Isabelle M; Coppoolse, Eric R; Verhoef-Post, Miriam; Schut, Johan W; de Rooij, Han; Vogelaar, Aat; Joosen, Ronny V L; Woudenberg, Leo; Comai, Luca; Bradford, Kent J

2016-11-01

Lettuce (Lactuca sativa) seeds exhibit thermoinhibition, or failure to complete germination when imbibed at warm temperatures. Chemical mutagenesis was employed to develop lettuce lines that exhibit germination thermotolerance. Two independent thermotolerant lettuce seed mutant lines, TG01 and TG10, were generated through ethyl methanesulfonate mutagenesis. Genetic and physiological analyses indicated that these two mutations were allelic and recessive. To identify the causal gene(s), we applied bulked segregant analysis by whole genome sequencing. For each mutant, bulked DNA samples of segregating thermotolerant (mutant) seeds were sequenced and analyzed for homozygous single-nucleotide polymorphisms. Two independent candidate mutations were identified at different physical positions in the zeaxanthin epoxidase gene (ABSCISIC ACID DEFICIENT 1/ZEAXANTHIN EPOXIDASE, or ABA1/ZEP) in TG01 and TG10. The mutation in TG01 caused an amino acid replacement, whereas the mutation in TG10 resulted in alternative mRNA splicing. Endogenous abscisic acid contents were reduced in both mutants, and expression of the ABA1 gene from wild-type lettuce under its own promoter fully complemented the TG01 mutant. Conventional genetic mapping confirmed that the causal mutations were located near the ZEP/ABA1 gene, but the bulked segregant whole genome sequencing approach more efficiently identified the specific gene responsible for the phenotype. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

Isolation and characterization of Tn917lac-generated competence mutants of Bacillus subtilis

International Nuclear Information System (INIS)

Hahn, J.; Albano, M.; Dubnau, D.

1987-01-01

The authors isolated 28 mutants of Bacillus subtilis deficient in the development of competence by using the transposon Tn917lacZ as a mutagen. The mutant strains were poorly transformable with plasmid and chromosomal DNAs but were normally transducible and exhibited wild-type resistance to DNA-damaging agents. The mutations were genetically mapped, and the mutants were characterized with respect to their abilities to bind and take up radiolabeled DNA. All were defective in uptake, and some failed to bind significantly amounts of DNA. The abilities of the mutant strains to resolve into two buoyant density classes on Renografin gradients were studied. Most resolved normally, but several banded in Renografin only at the buoyant density of noncompetent cells. The genetic mapping studies and the other analyses suggested that the mutations define a minimum of seven distinct com genes

Studies on induced partially resistant mutants of barley against powdery mildew

International Nuclear Information System (INIS)

Roebbelen, G.; Abdel-Hafez, A.G.; Reinhold, M.; Kwon, H.J.; Neuhaus-Steinmetz, J.P.; Heun, M.

1983-01-01

After mutagenic seed treatment of three partially resistant cultivars of spring barley with EMS and NaN 3 , 45 mutants in a first and 16 in a second experiment were selected in the M 2 -M 4 generations. The screening was done alternatively under natural infection in the field or controlled infection with a single pathotype in the greenhouse. These mutants exhibited a higher resistance and a higher susceptibility, respectively, than the initial cultivars Asse, Bomi and Vada. Some mutants expressed their altered resistance behaviour particularly during certain stages of development. High-level resistance was conditioned by mutation in the ml-o locus in three cases. For several Bomi mutants pathotype specificity with and without reversed ranking was proven as well as pathotype non-specificity in comparison with the reaction of the original cultivar. In 14 cases studied the inheritance of the involved mutants was monogenic recessive. The laevigatum locus responsible for the intermediate mildew resistance of Bomi was not affected by the mutations. Detection of groups of allelic mutants showed that there are at least two regions in the barley genome in which mutations for mildew resistance can occur rather frequently. In total, the past ten years of this mutation research have given convincing evidence that the strategies of mutant screening applied have yielded promising new material both for breeding and for progress in basic understanding of host-pathogen interactions. (author)

BACHD rats expressing full-length mutant huntingtin exhibit differences in social behavior compared to wild-type littermates.

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Giuseppe Manfré

Full Text Available Huntington disease (HD is a devastating inherited neurodegenerative disorder characterized by progressive motor, cognitive, and psychiatric symptoms without any cure to slow down or stop the progress of the disease. The BACHD rat model for HD carrying the human full-length mutant huntingtin protein (mHTT with 97 polyQ repeats has been recently established as a promising model which reproduces several HD-like features. While motor and cognitive functions have been characterized in BACHD rats, little is known about their social phenotype.This study focuses especially on social behavior since evidence for social disturbances exists in human patients. Our objective was to compare social behavior in BACHD and wild-type (WT rats at different ages, using two different measures of sociability.Animals were tested longitudinally at the age of 2, 4 and 8 months in the social interaction test to examine different parameters of sociability. A separate cohort of 7 month old rats was tested in the three chamber social test to measure both sociability and social novelty. Gene expression analyses in 8 months old animals were performed by real time qRT-PCR to evaluate a potential involvement of D1 and D2 dopaminergic receptors and the contribution of Brain-derived neurotrophic factor (BDNF to the observed behavioral alterations.In the social interaction test, BACHD rats showed age-dependent changes in behaviour when they were-re introduced to their cagemate after a 24 hours-period of individual housing. The time spent on nape attacks increased with aging. Furthermore, a significant higher level of pinning at 2 months of age was shown in the BACHD rats compared to wild-types, followed by a reduction at 4 and 8 months. On the other hand, BACHD rats exhibited a decreased active social behaviour compared to wild-types, reflected by genotype-effects on approaching, following and social nose contact. In the three chamber social test, BACHD rats seemed to show a mild

BACHD rats expressing full-length mutant huntingtin exhibit differences in social behavior compared to wild-type littermates.

Science.gov (United States)

Manfré, Giuseppe; Novati, Arianna; Faccini, Ilaria; Rossetti, Andrea C; Bosch, Kari; Molteni, Raffaella; Riva, Marco A; Van der Harst, Johanneke E; Nguyen, Huu Phuc; Homberg, Judith R

2018-01-01

Huntington disease (HD) is a devastating inherited neurodegenerative disorder characterized by progressive motor, cognitive, and psychiatric symptoms without any cure to slow down or stop the progress of the disease. The BACHD rat model for HD carrying the human full-length mutant huntingtin protein (mHTT) with 97 polyQ repeats has been recently established as a promising model which reproduces several HD-like features. While motor and cognitive functions have been characterized in BACHD rats, little is known about their social phenotype. This study focuses especially on social behavior since evidence for social disturbances exists in human patients. Our objective was to compare social behavior in BACHD and wild-type (WT) rats at different ages, using two different measures of sociability. Animals were tested longitudinally at the age of 2, 4 and 8 months in the social interaction test to examine different parameters of sociability. A separate cohort of 7 month old rats was tested in the three chamber social test to measure both sociability and social novelty. Gene expression analyses in 8 months old animals were performed by real time qRT-PCR to evaluate a potential involvement of D1 and D2 dopaminergic receptors and the contribution of Brain-derived neurotrophic factor (BDNF) to the observed behavioral alterations. In the social interaction test, BACHD rats showed age-dependent changes in behaviour when they were-re introduced to their cagemate after a 24 hours-period of individual housing. The time spent on nape attacks increased with aging. Furthermore, a significant higher level of pinning at 2 months of age was shown in the BACHD rats compared to wild-types, followed by a reduction at 4 and 8 months. On the other hand, BACHD rats exhibited a decreased active social behaviour compared to wild-types, reflected by genotype-effects on approaching, following and social nose contact. In the three chamber social test, BACHD rats seemed to show a mild deficit in

BACHD rats expressing full-length mutant huntingtin exhibit differences in social behavior compared to wild-type littermates

Science.gov (United States)

Manfré, Giuseppe; Novati, Arianna; Faccini, Ilaria; Rossetti, Andrea C.; Bosch, Kari; Molteni, Raffaella; Riva, Marco A.; Van der Harst, Johanneke E.; Homberg, Judith R.

2018-01-01

Background Huntington disease (HD) is a devastating inherited neurodegenerative disorder characterized by progressive motor, cognitive, and psychiatric symptoms without any cure to slow down or stop the progress of the disease. The BACHD rat model for HD carrying the human full-length mutant huntingtin protein (mHTT) with 97 polyQ repeats has been recently established as a promising model which reproduces several HD-like features. While motor and cognitive functions have been characterized in BACHD rats, little is known about their social phenotype. Objective This study focuses especially on social behavior since evidence for social disturbances exists in human patients. Our objective was to compare social behavior in BACHD and wild-type (WT) rats at different ages, using two different measures of sociability. Methods Animals were tested longitudinally at the age of 2, 4 and 8 months in the social interaction test to examine different parameters of sociability. A separate cohort of 7 month old rats was tested in the three chamber social test to measure both sociability and social novelty. Gene expression analyses in 8 months old animals were performed by real time qRT-PCR to evaluate a potential involvement of D1 and D2 dopaminergic receptors and the contribution of Brain-derived neurotrophic factor (BDNF) to the observed behavioral alterations. Results In the social interaction test, BACHD rats showed age-dependent changes in behaviour when they were-re introduced to their cagemate after a 24 hours-period of individual housing. The time spent on nape attacks increased with aging. Furthermore, a significant higher level of pinning at 2 months of age was shown in the BACHD rats compared to wild-types, followed by a reduction at 4 and 8 months. On the other hand, BACHD rats exhibited a decreased active social behaviour compared to wild-types, reflected by genotype-effects on approaching, following and social nose contact. In the three chamber social test, BACHD rats

Diabetes and exocrine pancreatic insufficiency in E2F1/E2F2 double-mutant mice.

Science.gov (United States)

Iglesias, Ainhoa; Murga, Matilde; Laresgoiti, Usua; Skoudy, Anouchka; Bernales, Irantzu; Fullaondo, Asier; Moreno, Bernardino; Lloreta, José; Field, Seth J; Real, Francisco X; Zubiaga, Ana M

2004-05-01

E2F transcription factors are thought to be key regulators of cell growth control. Here we use mutant mouse strains to investigate the function of E2F1 and E2F2 in vivo. E2F1/E2F2 compound-mutant mice develop nonautoimmune insulin-deficient diabetes and exocrine pancreatic dysfunction characterized by endocrine and exocrine cell dysplasia, a reduction in the number and size of acini and islets, and their replacement by ductal structures and adipose tissue. Mutant pancreatic cells exhibit increased rates of DNA replication but also of apoptosis, resulting in severe pancreatic atrophy. The expression of genes involved in DNA replication and cell cycle control was upregulated in the E2F1/E2F2 compound-mutant pancreas, suggesting that their expression is repressed by E2F1/E2F2 activities and that the inappropriate cell cycle found in the mutant pancreas is likely the result of the deregulated expression of these genes. Interestingly, the expression of ductal cell and adipocyte differentiation marker genes was also upregulated, whereas expression of pancreatic cell marker genes were downregulated. These results suggest that E2F1/E2F2 activity negatively controls growth of mature pancreatic cells and is necessary for the maintenance of differentiated pancreatic phenotypes in the adult.

Isolation and characterization of prophage mutants of the defective Bacillus subtilis bacteriophage PBSX

International Nuclear Information System (INIS)

Thurm, P.; Garro, A.J.

1975-01-01

Bacillus subtilis mutants with lesions in PBSX prophage genes have been isolated. One of these appears to be a regulatory mutant and is defective for mitomycin C-induced derepression of PBSX; the others are defective for phage capsid formation. All of the PBSX structural proteins are synthesized during induction of the capsid defective mutants; however, several of these proteins exhibit abnormal serological reactivity with anti-PBSX antiserum. The two head proteins X4 and X7 are not immunoprecipitable in a mutant which fails to assemble phage head structures. In the tail mutant, proteins X5 and X6 are not immunoprecipitable, tails are not assembled, and a possible tail protein precursor remains uncleaved. The noninducible mutant does not synthesize any PBSX structural proteins after exposure to mitomycin C. The mutation is specific for PBSX since phi 105 and SPO2 lysogens of the mutant are inducible. All of the known PBSX-specific mutations were shown to be clustered between argC and metC on the host chromosome. In addition, the metC marker was shown to be present in multiple copies in cells induced for PBSX replication. This suggests that the derepressed prophage replicates while still integrated and that replication extends into the adjacent regions of the host chromosome

Induction of short culm mutants for bread wheat by using gamma rays

International Nuclear Information System (INIS)

Sobieh, S.S.

2002-01-01

This investigation was conducted at the experimental farm of plant research department, nuclear research center, atomic energy authority, Inshas in order to select some short culm mutants from the local wheat varieties; Sid's-5, Sid's-6 and Sid's-7 after gamma irradiation. The obtained results indicated that: 1-M 4 mutants progenies retained the features of their M 3 selections. 2-Some short culm mutants exhibited high grain yield/plant as compared to their original varieties. 3-There were significant decreases in plant height varied from 21.4 to 35.4%. This reduction was due to the shorting of culm inter nods length. As well as, the reduction diameter/culm especially diameter of the inter nods/culm did not differed between original varieties and the mutants. 4-The correlation between grain yield/plant and number of spikes/plant was positive and highly significant for most mutants and the original varieties as well. Data also showed that there were positive relationship between grain yield/plant and number of grains/spike and and length of the inter nods/culm. Positive or negative association between grain yield/plant and plant height as well as diameters of inter nods/culm for mutants and original varieties were detected

Analysis of nutritional quality of low phytic acid mutants in maize

International Nuclear Information System (INIS)

Yuan Ming'an; Luo Hongbing; Wang Zhonghua; Chen Jinhong; Mei Shufang; Shu Xiaoli; Wu Dianxing

2008-01-01

Major nutritional quality and components of eight low phytic acid (lpa) mutants and their corresponding wild types were studied. Compared to their corresponding wild types, the content of inorganic P (Pi) was all increased several times, while the content of total P (TP) in mutants was almost the same as their wild types. The contents of crude lipid and amylose were similar, but total starch was significantly different. Crude protein in some of mutants was increased significantly. Most of amino acids were increased, and essential amino acid-Lysine was increased except mutants derived from Q319 and X178. Mineral macronutrients and micronutrients were similar. All results showed that the lpa mutation in maize could enhance the nutritional quality and bioactivities. (authors)

17-AAG increases autophagic removal of mutant androgen receptor in spinal and bulbar muscular atrophy.

Science.gov (United States)

Rusmini, Paola; Simonini, Francesca; Crippa, Valeria; Bolzoni, Elena; Onesto, Elisa; Cagnin, Monica; Sau, Daniela; Ferri, Nicola; Poletti, Angelo

2011-01-01

Several types of motorneuron diseases are linked to neurotoxic mutant proteins. These acquire aberrant conformations (misfolding) that trigger deleterious downstream events responsible for neuronal dysfunction and degeneration. The pharmacological removal of misfolded proteins might thus be useful in these diseases. We utilized a peculiar motorneuronal disease model, spinobulbar muscular atrophy (SBMA), in which the neurotoxicity of the protein involved, the mutant androgen receptor (ARpolyQ), can be modulated by its ligand testosterone (T). 17-(allylamino)-17-demethoxygeldanamycin (17-AAG) has already been proven to exert beneficial action in SBMA. Here we demonstrated that 17-AAG exerts its pro-degradative activity on mutant ARpolyQ without impacting on proteasome functions. 17-AAG removes ARpolyQ misfolded species and aggregates by activating the autophagic system. We next analyzed the 17-AAG effects on two proteins (SOD1 and TDP-43) involved in related motorneuronal diseases, such as amyotrophic lateral sclerosis (ALS). In these models 17-AAG was unable to counteract protein aggregation. Copyright © 2010 Elsevier Inc. All rights reserved.

Mutant p97 exhibits species-specific changes of its ATPase activity and compromises the UBXD9-mediated monomerisation of p97 hexamers.

Science.gov (United States)

Rijal, Ramesh; Arhzaouy, Khalid; Strucksberg, Karl-Heinz; Cross, Megan; Hofmann, Andreas; Schröder, Rolf; Clemen, Christoph S; Eichinger, Ludwig

2016-01-01

p97 (VCP) is a homo-hexameric triple-A ATPase that exerts a plethora of cellular processes. Heterozygous missense mutations of p97 cause at least five human neurodegenerative disorders. However, the specific molecular consequences of p97 mutations are hitherto widely unknown. Our in silico structural models of human and Dictyostelium p97 showed that the disease-causing human R93C, R155H, and R155C as well as Dictyostelium R154C, E219K, R154C/E219K p97 mutations constitute variations in surface-exposed locations. In-gel ATPase activity measurements of p97 monomers and hexamers revealed significant mutation- and species-specific differences. While all human p97 mutations led to an increase in ATPase activity, no changes could be detected for the Dictyostelium R154C mutant, which is orthologous to human R155C. The E219K mutation led to an almost complete loss of activity, which was partially recuperated in the R154C/E219K double-mutant indicating p97 inter-domain communication. By means of co-immunoprecipitation experiments we identified an UBX-domain containing Dictyostelium protein as a novel p97 interaction partner. We categorized all UBX-domain containing Dictyostelium proteins and named the interaction partner UBXD9. Pull-down assays and surface plasmon resonance analyses of Dictyostelium UBXD9 or the human orthologue TUG/ASPL/UBXD9 demonstrated direct interactions with p97 as well as species-, mutation- and ATP-dependent differences in the binding affinities. Sucrose density gradient assays revealed that both human and Dictyostelium UBXD9 proteins very efficiently disassembled wild-type, but to a lesser extent mutant p97 hexamers into monomers. Our results are consistent with a scenario in which p97 point mutations lead to differences in enzymatic activities and molecular interactions, which in the long-term result in a late-onset and progressive multisystem disease. Copyright © 2016 The Authors. Published by Elsevier GmbH.. All rights reserved.

Zebrafish enpp1 mutants exhibit pathological mineralization, mimicking features of generalized arterial calcification of infancy (GACI and pseudoxanthoma elasticum (PXE

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Alexander Apschner

2014-07-01

Full Text Available In recent years it has become clear that, mechanistically, biomineralization is a process that has to be actively inhibited as a default state. This inhibition must be released in a rigidly controlled manner in order for mineralization to occur in skeletal elements and teeth. A central aspect of this concept is the tightly controlled balance between phosphate, a constituent of the biomineral hydroxyapatite, and pyrophosphate, a physiochemical inhibitor of mineralization. Here, we provide a detailed analysis of a zebrafish mutant, dragonfish (dgf, which is mutant for ectonucleoside pyrophosphatase/phosphodiesterase 1 (Enpp1, a protein that is crucial for supplying extracellular pyrophosphate. Generalized arterial calcification of infancy (GACI is a fatal human disease, and the majority of cases are thought to be caused by mutations in ENPP1. Furthermore, some cases of pseudoxanthoma elasticum (PXE have recently been linked to ENPP1. Similar to humans, we show here that zebrafish enpp1 mutants can develop ectopic calcifications in a variety of soft tissues – most notably in the skin, cartilage elements, the heart, intracranial space and the notochord sheet. Using transgenic reporter lines, we demonstrate that ectopic mineralizations in these tissues occur independently of the expression of typical osteoblast or cartilage markers. Intriguingly, we detect cells expressing the osteoclast markers Trap and CathepsinK at sites of ectopic calcification at time points when osteoclasts are not yet present in wild-type siblings. Treatment with the bisphosphonate etidronate rescues aspects of the dgf phenotype, and we detected deregulated expression of genes that are involved in phosphate homeostasis and mineralization, such as fgf23, npt2a, entpd5 and spp1 (also known as osteopontin. Employing a UAS-GalFF approach, we show that forced expression of enpp1 in blood vessels or the floorplate of mutant embryos is sufficient to rescue the notochord

Optimization of biomass production of a mutant of Yarrowia lipolytica with an increased lipase activity using raw glycerol

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Miguel A Galvagno

2011-09-01

Full Text Available The yeast Yarrowia lipolytica accumulates oils and is able to produce extracellular lipases when growing in different carbon sources including glycerol, the principal by-product of the biodiesel industry. In this study, biomass production of a novel mutant strain of Y. lipolytica was statistically optimized by Response Surface Methodology in media containing biodiesel-derived glycerol as main carbon source. This strain exhibited distinctive morphological and fatty acid profile characteristics, and showed an increased extracellular lipase activity. An organic source of nitrogen and the addition of 1.0 g/l olive oil were necessary for significant lipase production. Plackett-Burman and Central Composite Statistical Designs were employed for screening and optimization of fermentation in shaken flasks cultures, and the maximum values obtained were 16.1 g/l for biomass and 12.2 Units/ml for lipase, respectively. Optimized batch bioprocess was thereafter scaled in aerated bioreactors and the values reached for lipase specific activity after 95 % of the glycerol had been consumed, were three-fold higher than those obtained in shaken flasks cultures. A sustainable bioprocess to obtain biomass and extracellular lipase activity was attained by maximizing the use of the by-products of biodiesel industry.Optimización de la producción de biomasa usando glicerol crudo, de una cepa mutante de Yarrowia lipolytica con actividad incrementada de lipasa. La levadura Yarrowia lipolytica acumula aceites y produce una lipasa extracelular al crecer en diferentes fuentes de carbono, entre ellas el glicerol, principal subproducto de la creciente industria del biodiésel. En el presente trabajo, se optimizó mediante la metodología de superficies de respuesta la producción de biomasa de una nueva cepa mutante de Y. lipolytica, empleando medios con glicerol derivado de la industria del biodiésel como principal fuente de carbono. Esta cepa presentó caracter

Spontaneous nisin-resistant Listeria monocytogenes mutants with increased expression of a putative penicillin-binding protein and their sensitivity to various antibiotics

DEFF Research Database (Denmark)

Gravesen, Anne; Sorensen, K.; Aarestrup, Frank Møller

2001-01-01

-molecular-weight penicillin-binding proteins (PBPs), a histidine protein kinase, a protein of unknown function, and ClpB (putative functions from homology), The three former proteins had increased expression in a total of six out of 10 independent mutants originating from five different wildtype strains, indicating...

Mutation of the Glucosinolate Biosynthesis Enzyme Cytochrome P450 83A1 Monooxygenase Increases Camalexin Accumulation and Powdery Mildew Resistance.

Science.gov (United States)

Liu, Simu; Bartnikas, Lisa M; Volko, Sigrid M; Ausubel, Frederick M; Tang, Dingzhong

2016-01-01

Small secondary metabolites, including glucosinolates and the major phytoalexin camalexin, play important roles in immunity in Arabidopsis thaliana. We isolated an Arabidopsis mutant with increased resistance to the powdery mildew fungus Golovinomyces cichoracearum and identified a mutation in the gene encoding cytochrome P450 83A1 monooxygenase (CYP83A1), which functions in glucosinolate biosynthesis. The cyp83a1-3 mutant exhibited enhanced defense responses to G. cichoracearum and double mutant analysis showed that this enhanced resistance requires NPR1, EDS1, and PAD4, but not SID2 or EDS5. In cyp83a1-3 mutants, the expression of genes related to camalexin synthesis increased upon G. cichoracearum infection. Significantly, the cyp83a1-3 mutant also accumulated higher levels of camalexin. Decreasing camalexin levels by mutation of the camalexin synthetase gene PAD3 or the camalexin synthesis regulator AtWRKY33 compromised the powdery mildew resistance in these mutants. Consistent with these observations, overexpression of PAD3 increased camalexin levels and enhanced resistance to G. cichoracearum. Taken together, our data indicate that accumulation of higher levels of camalexin contributes to increased resistance to powdery mildew.

Mutation of the glucosinolate biosynthesis enzyme cytochrome P450 83A1 monooxygenase increases camalexin accumulation and powdery mildew resistance

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Simu eLiu

2016-03-01

Full Text Available Small secondary metabolites, including glucosinolates and the major phytoalexin camalexin, play important roles in immunity in Arabidopsis thaliana. We isolated an Arabidopsis mutant with increased resistance to the powdery mildew fungus Golovinomyces cichoracearum and identified a mutation in the gene encoding cytochrome P450 83A1 monooxygenase (CYP83A1, which functions in glucosinolate biosynthesis. The cyp83a1-3 mutant exhibited enhanced defense responses to G. cichoracearum and double mutant analysis showed that this enhanced resistance requires NPR1, EDS1, and PAD4, but not SID2 or EDS5. In cyp83a1-3 mutants, the expression of genes related to camalexin synthesis increased upon G. cichoracearum infection. Significantly, the cyp83a1-3 mutant also accumulated higher levels of camalexin. Decreasing camalexin levels by mutation of the camalexin synthetase gene PAD3 or the camalexin synthesis regulator AtWRKY33 compromised the powdery mildew resistance in these mutants. Consistent with these observations, overexpression of PAD3 increased camalexin levels and enhanced resistance to G. cichoracearum. Taken together, our data indicate that accumulation of higher levels of camalexin contributes to increased resistance to powdery mildew.

Preliminary Study of the Characteristics of Several Glossy Cabbage (Brassica oleracea var. capitata L. Mutants

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Tang Jun

2015-09-01

Full Text Available To determine the characteristics and potential practical applications of glossy cabbage (Brassica oleracea var. capitata L. mutants, five different glossy mutants were studied. The amount of epicuticular wax covering the mutant leaves was only approximately 30% that of the wild-type (WT leaves. The wax crystals of WT plants were columnar and linear, while they were granular and rod-shaped in the mutants. Additionally, in WT cabbage, the primary wax components were alkanes, alcohols, fatty acids, ketones, and aldehydes. There was a significant decrease in the abundance of alkanes and ketones in the wax of the mutants. The glossy-green trait of the mutants may be the result of an inhibited alkane-forming pathway. Higher rates of chlorophyll leaching and water loss demonstrate that the mutant leaves were more permeable and sensitive to drought stress than the WT leaves. Growth curve results indicated that the growth rate of mutant-1 and mutant-3 was slower than that of the corresponding WT cabbage, resulting in shorter plants. However, the growth rate of mutant-2 was not influenced by the lack of coating wax. An investigation of the agronomic traits and heterosis of the glossy cabbage mutants indicated that all five mutants had glossy-green leaves, which was a favorable characteristic. The F1 plants derived from crosses involving mutant-2 exhibited obvious heterosis, suggesting the observed glossy-green trait is controlled by a dominant gene. Therefore, mutant-2 may be useful as a source of genetic material for future cabbage breeding experiments.

Enhanced production of bacitracin by a mutant strain bacillus licheniformis UV-MN-HN-8 (enhanced bacitracin production by mutagenesis)

International Nuclear Information System (INIS)

Aftab, M.N.; Ikram-ul-Haq; Baig, S.

2010-01-01

The present study is focused on the improvement of Bacillus licheniformis through random mutagenesis to obtain mutant having enhanced production of bacitracin. Many isolates of Bacillus licheniformis were isolated and the isolate GP-40 produced maximum bacitracin production (16 +- 0.72 IU/mL). Treatment of Bacillus licheniformis GP-40 with ultraviolet (UV) radiations increased bacitracin production to 29 +- 0.69 IU/mL. Similarly, treatment of vegetative cells of GP-40 with chemicals like N-methyl N'-nitro N-nitroso guanidine (MNNG) and Nitrous acid (HNO/sub 2/) increased bacitracin production to 35 +- 1.35 IU/mL and 29 +- 0.89 IU/mL respectively. Studies regarding the combined effect of UV and chemical treatment on parental cells exhibited significantly higher titers of bacitracin with maximum bacitracin production reached to 47.6 +- 0.92 IU/mL. An increase of 2.97 fold production of bacitracin in comparison to wild type was observed. Mutant strain was highly stable and produced consistent yield of bacitracin even after 15 generations. On the basis of kinetic variables, notably mu (h-/sup 1/)max, Yp/x, qp, Qp and Qx mutant strain B. licheniformis UV-MN-HN-8 was found to be a hyper producer of bacitracin. (author)

Mutations at the mei-41, mus(1)101, mus(1)103, mus(2)205 and mus(3)310 loci of Drosophila exhibit differential UDS responses with different DNA-damaging agents

International Nuclear Information System (INIS)

Dusenbery, R.L.

1987-01-01

5 mutagen-sensitive mutants of Drosophila melanogaster, reported to perform normal or only slightly reduced excision repair of UV damage, were examined by an unscheduled DNA synthesis (UDS) assay. 2 mutants, classified as completely or partially proficient for both excision and postreplication repair of UV damage, mus(1)103 and mus(2)205, were found to give positive UDS responses only for UV damage. These mutants exhibit no measurable UDS activity following DNA damage by several different alkylating agents and X-rays. 3 mutants, classified as having no defect in excision repair, but measurable defects in postreplication repair of UV damage, exhibit 3 different response patterns. The mutant mei-41 exhibits a highly positive UDS response following damage by all agents, consistent with its prior classification as excision-repair-proficient, but postreplication-repair-deficient for UV damage. The mutant mus(1)101, however, exhibits a strong positive UDS response following only UV damage and appears to be blocked in the excision repair of damage produced by both alkylating agents and X-irradiation. Finally, mus(3)310 exhibits no UDS response to alkylation, X-ray or UV damage. This is not consistent with its previous classification. Results obtained w0272the qualitative in vitro UDS assay are entirely consistent with the results from two separate in vivo measures of excision repair deficiency followign DNA damage, larval hypersensitivity to killing and hypermutability in the sex-linked recessive lethal test. (Auth.)

Stability Test For Sorghum Mutant Lines Derived From Induced Mutations with Gamma-Ray Irradiation

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S. Human

2011-12-01

Full Text Available Sorghum breeding program had been conducted at the Center for the Application of Isotopes and Radiation Technology, BATAN. Plant genetic variability was increased through induced mutations using gamma-ray irradiation. Through selection process in successive generations, some promising mutant lines had been identified to have good agronomic characteristics with high grain yield. These breeding lines were tested in multi location trials and information of the genotypic stability was obtained to meet the requirements for officially varietal release by the Ministry of Agriculture. A total of 11 sorghum lines and varieties consisting of 8 mutant lines derived from induced mutations (B-100, B-95, B-92, B-83, B-76, B-75, B-69 and Zh-30 and 3 control varieties (Durra, UPCA-S1 and Mandau were included in the experiment. All materials were grown in 10 agro-ecologically different locations namely Gunungkidul, Bantul, Citayam, Garut, Lampung, Bogor, Anyer, Karawaci, Cianjur and Subang. In each location, the local adaptability test was conducted by randomized block design with 3 replications. Data of grain yield was used for evaluating genotypic stability using AMMI approach. Results revealed that sorghum mutation breeding had generated 3 mutant lines (B-100, B-76 and Zh-30 exhibiting grain yield significantly higher than the control varieties. These mutant lines were genetically stable in all locations so that they would be recommended for official release as new sorghum varieties to the Ministry of Agriculture

Biological changes in Barley mutants resistant to powdery mildew disease

International Nuclear Information System (INIS)

Amer, I. M.; Fahim, M. M.; Moustafa, N. A.

2012-12-01

physiological studies showed that all kinds of chlorophyll (a), (b) and (a + b) content in infected plant were decreased while, the carotenes pigment were increased. Infection generally reduced total sugars content of all resistant mutants. Infected resistant mutant showed more phenols content and peroxidase, polyphenoloxidase activities than healthy ones of the mutants. (Author)

A mutant of a mutant of a mutant of a ...: Irradiation of progressive radiation-induced mutants in a mutation-breeding programme with Chrysanthenum morifolium RAM

International Nuclear Information System (INIS)

Broertjes, C.; Koene, P.; Veen, J.W.H. van.

1980-01-01

Radiation-induced sports in Chrysanthemum morifolium RAM. have been reported for several years. It has become an everyday practice to produce flower-colour mutants from outstanding cross-breeding products, even before they are distributed for the commercial production of cut flowers. One of the most successful and recent examples is that of cv. Horim, of which hundreds of mutants were produced by successive use of radiation-induced mutants in the mutation-breeding programme. Over about 4 years a variety of flower-colour mutants was obtained, not only largely including the outstanding characteristics of the original cultivar but sometimes even with an appreciable improvement in quality and yield. It is expected that the latter types, the Miros group, will soon completely supersede the spontaneous or raditation-induced Horim sports and mutants and take over the leading position of the Horim group in the production of all-year-round (AYR) cut-flowers. (orig.)

Polyploidy and chromosomal aberrations induced by mutagens in open flowering sterile mutants of spring barley

Energy Technology Data Exchange (ETDEWEB)

Manzyuk, V T; Kozachenko, M R; Kirichenko, V V

1975-01-01

Two types of aberration in meiosis were observed which induced sterility in chemical and radiational mutations of spring wheat: asynapsis and absence of cytokinesis, and chromosomal aberrations in the form of bridges and fragments. Gamma-mutants have many more chromosomal aberrations in the form of fragments, bridges and cells with micronuclei than do chemical mutants. The percent of tetrads with micronuclei is 1.5-2 times greater than the number of dyads with such nuclei. We obtained an original gamma-mutant exhibiting depolyploidization and polyploidization in the mother cells; we also observed cells possessing chromosomal associations of n, 2n, 4n, 68, 8n and greater.

UV-induced lethal sectoring and pure mutant clones in yeast.

Science.gov (United States)

Hannan, M A; Duck, P; Nasim, A

1976-08-01

The induction of lethal sectoring and pure mutant clones by ultraviolet light has been studied in a homogeneous G1 population of Saccharomyces cerevisiae grown in a normal growth medium. At the lowest UV dose of 250 ergs, which corresponds to a shoulder in the survival curve, all mutants appeared as pure clones. At higher doses the frequency of mosaic mutants progressively increased. These results indicate a relationship between the highest frequency of complete mutants and the maximum repair activity. In addition, the frequency of lethal sectoring at all doses tested was too low to account for the origin of pure mutant clones.

Drastic anthocyanin increase in response to PAP1 overexpression in fls1 knockout mutant confers enhanced osmotic stress tolerance in Arabidopsis thaliana.

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Lee, Won Je; Jeong, Chan Young; Kwon, Jaeyoung; Van Kien, Vu; Lee, Dongho; Hong, Suk-Whan; Lee, Hojoung

2016-11-01

KEY MESSAGE : pap1 - D/fls1ko double mutant plants that produce substantial amounts of anthocyanin show tolerance to abiotic stress. Anthocyanins are flavonoids that are abundant in various plants and have beneficial effects on both plants and humans. Many genes in flavonoid biosynthetic pathways have been identified, including those in the MYB-bHLH-WD40 (MBW) complex. The MYB gene Production of Anthocyanin Pigment 1 (PAP1) plays a particularly important role in anthocyanin accumulation. PAP1 expression in many plant systems strongly increases anthocyanin levels, resulting in a dark purple color in many plant organs. In this study, we generated double mutant plants that harbor fls1ko in the pap1-D background (i.e., pap1-D/fls1ko plants), to examine whether anthocyanins can be further enhanced by blocking flavonol biosynthesis under PAP1 overexpression. We also wanted to examine whether the increased anthocyanin levels contribute to defense against osmotic stresses. The pap1-D/fls1ko mutants accumulated higher anthocyanin levels than pap1-D plants in both control and sucrose-treated conditions. However, flavonoid biosynthesis genes were slightly down-regulated in the pap1-D/fls1ko seedlings as compared to their expression in pap1-D seedlings. We also report the performance of pap1-D/fls1ko seedlings in response to plant osmotic stresses.

Molecular analyses of in vivo hprt mutant T cells from atomic bomb survivors

International Nuclear Information System (INIS)

Hakoda, M.; Hirai, Y.; Kyoizumi, S.; Akiyama, M.

1989-01-01

In vivo-derived hprt-deficient mutant T cells isolated from three nonirradiated controls and two atomic bomb survivors were studied by Southern blot analysis to investigate the molecular spectra of the mutations. Mutant frequencies for the three controls were 1.8, 2.3, and 7.3 x 10(-6), and those for the two survivors (who had received radiation doses of 2.46 and 2.15 Gy, based upon the revised atomic bomb shielded kerma estimates) were 9.3 and 14.4 x 10(-6), respectively. Fourteen (13%) of 105 mutant T-cell colonies from the controls showed various structural changes in the hprt gene. The frequency of mutants with hprt gene structural changes in one atomic bomb survivor, who exhibited a mutant frequency of 9.3 x 10(-6), was 26% (16/61), which was significantly higher than that of the controls. However, the frequency of structural changes in the other survivor (14%, 8/59) was not higher than that of the controls. Two sets of mutants (in total, eight mutants) from the survivor, who showed a significantly higher frequency of mutants with hprt gross alterations than did the controls, had the same hprt changes and the same rearrangements of T-cell receptor (TcR) beta- and gamma-chain genes, indicating a clonal expansion from one progenitor mutant. This phenomenon may reflect an in vivo recovery process of T cells in the periphery after exposure to atomic bomb radiation. However, when comparing the frequency of mutations, these two sets of mutants should be reduced. After reducing the total number of mutants from the number of gross hprt changes, the frequency was not significantly higher than that of the controls

Radiation induced mutants in cassava (Manihot esculenta Crantz)

International Nuclear Information System (INIS)

Nayar, G.G.; Rajendran, P.G.

1987-01-01

Full text: Stem cuttings and true seeds of three promising cultivars of cassava were exposed respectively to 1 to 5 kR and 10 to 50 kR acute gamma rays from a 60 Co source. Treatments of stem cuttings beyond 5 kR and seeds beyond 50 kR were lethal. One mutant each in the cultivars M4, H-165 and H-2304 was obtained from the stem irradiated populations. Another mutant was found in the seed irradiated progeny of H-2304. The mutant of M4 is characterised by light green (chlorina) leaves. The mutant of H-165 shows significantly shorter petiole (22,5 against 35.2 cm) and narrow leaf lobes, while the H-2304 mutant shows speckled leaves, branching and early flowering. The mutant found in the seed irradiated progeny of H-2304 is having yellow tuber flesh indicating the presence of carotene. The mutants may be useful in studies related to basic information as well as in practical breeding. The chlorina mutant in M4 showed slow growth and high HCN content in leaves. Late branching may be a useful trait in the traditionally non-branching clones of cassava to maintain the desirable leaf area index during high leaf fall period. Early flowering could be useful in a recombinant breeding programme. The tuber yield of the short petiole mutant in H-165 increased by 20% - 25% through closer planting. The narrow leaf lobes of this mutant permit better light penetration to lower leaves. (author)

A Simple and Rapid Gene Disruption Strategy in Mycobacterium abscessus: On the Design and Application of Glycopeptidolipid Mutants.

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Viljoen, Albertus; Gutiérrez, Ana Victoria; Dupont, Christian; Ghigo, Eric; Kremer, Laurent

2018-01-01

Little is known about the disease-causing genetic determinants that are used by Mycobacterium abscessus , increasingly acknowledged as an important emerging pathogen, notably in cystic fibrosis. The presence or absence of surface exposed glycopeptidolipids (GPL) conditions the smooth (S) or rough (R) M. abscessus subsp. abscessus ( M. abscessus ) variants, respectively, which are characterized by distinct infective programs. However, only a handful of successful gene knock-out and conditional mutants have been reported in M. abscessus , testifying that genetic manipulation of this mycobacterium is difficult. To facilitate gene disruption and generation of conditional mutants in M. abscessus , we have designed a one-step single cross-over system that allows the rapid and simple generation of such mutants. Cloning of as small as 300 bp of the target gene allows for efficient homologous recombination to occur without additional exogenous recombination-promoting factors. The presence of tdTomato on the plasmids allows easily sifting out the large background of mutants spontaneously resistant to antibiotics. Using this strategy in the S genetic background and the target gene mmpL4a , necessary for GPL synthesis and transport, nearly 100% of red fluorescent clones exhibited a rough morphotype and lost GPL on the surface, suggesting that most red fluorescent colonies obtained after transformation incorporated the plasmid through homologous recombination into the chromosome. This system was further exploited to generate another strain with reduced GPL levels to explore how the presence of these cell wall-associated glycolipids influences M. abscessus hydrophobicity as well as virulence in the zebrafish model of infection. This mutant exhibited a more pronounced killing phenotype in zebrafish embryos compared to its S progenitor and this effect correlated with the production of abscesses in the central nervous system. Overall, these results suggest that the near

Probiotic features of Lactobacillus plantarum mutant strains.

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Bove, Pasquale; Gallone, Anna; Russo, Pasquale; Capozzi, Vittorio; Albenzio, Marzia; Spano, Giuseppe; Fiocco, Daniela

2012-10-01

In this study, the probiotic potential of Lactobacillus plantarum wild-type and derivative mutant strains was investigated. Bacterial survival was evaluated in an in vitro system, simulating the transit along the human oro-gastro-intestinal tract. Interaction with human gut epithelial cells was studied by assessing bacterial adhesive ability to Caco-2 cells and induction of genes involved in innate immunity. L. plantarum strains were resistant to the combined stress at the various steps of the simulated gastrointestinal tract. Major decreases in the viability of L. plantarum cells were observed mainly under drastic acidic conditions (pH ≤ 2.0) of the gastric compartment. Abiotic stresses associated to small intestine poorly affected bacterial viability. All the bacterial strains significantly adhered to Caco-2 cells, with the ΔctsR mutant strain exhibiting the highest adhesion. Induction of immune-related genes resulted higher upon incubation with heat-inactivated bacteria rather than with live ones. For specific genes, a differential transcriptional pattern was observed upon stimulation with different L. plantarum strains, evidencing a possible role of the knocked out bacterial genes in the modulation of host cell response. In particular, cells from Δhsp18.55 and ΔftsH mutants strongly triggered immune defence genes. Our study highlights the relevance of microbial genetic background in host-probiotic interaction and might contribute to identify candidate bacterial genes and molecules involved in probiosis.

Mutation of a vitelline membrane protein, BmEP80, is responsible for the silkworm "Ming" lethal egg mutant.

Science.gov (United States)

Chen, Anli; Gao, Peng; Zhao, Qiaoling; Tang, Shunming; Shen, Xingjia; Zhang, Guozheng; Qiu, Zhiyong; Xia, Dingguo; Huang, Yongping; Xu, Yunmin; He, Ningjia

2013-02-25

The egg stage is an important stage in the silkworm (Bombyx mori) life cycle. Normal silkworm eggs are usually short, elliptical, and laterally flattened, with a sometimes hollowed surface on the lateral side. However, the eggs laid by homozygous recessive "Ming" lethal egg mutants (l-e(m)) lose water and become concaved around 1h, ultimately exhibiting a triangular shape on the egg surfaces. We performed positional cloning, and narrowed down the region containing the gene responsible for the l-e(m) mutant to 360 kb on chromosome 10 using 2287 F(2) individuals. Using expression analysis and RNA interference, the best l-e(m) candidate gene was shown to be BmEP80. The results of the inverse polymerase chain reaction showed that an ~1.9 kb region from the 3' untranslated region of BmVMP23 to the forepart of BmEP80 was replaced by a >100 kb DNA fragment in the l-e(m) mutant. Several eggs laid by the normal moths injected with BmEP80 small interfering RNAs were evidently depressed and exhibited a triangular shape on the surface. The phenotype exhibited was consistent with the eggs laid by the l-e(m) mutant. Moreover, two-dimensional gel electrophoresis showed that the BmEP80 protein was expressed in the ovary from the 9th day of the pupa stage to eclosion in the wild-type silkworm, but was absent in the l-e(m) mutant. These results indicate that BmEP80 is responsible for the l-e(m) mutation. Copyright © 2012 Elsevier B.V. All rights reserved.

Increasing awareness and preparedness by an exhibition and studying the effect of visuals

Science.gov (United States)

Charrière, Marie; Bogaard, Thom; Malet, Jean-Philippe; Mostert, Erik

2013-04-01

Damages caused by natural hazards can be reduced not only by protection, management and intervention activities, but also by information and communication to improve awareness and preparedness of local communities and tourists. Risk communication is particularly crucial for mountainous areas, such as the Ubaye Valley (France), as they are affected by multiple hazards and are particularly sensitive to the potential effects of climate and socio-economic changes which may increase the risk associated with natural hazards significantly. An exhibition is a powerful tool to communicate with the general public. It allows1: (1) targeting specific audiences, (2) transmitting technical and scientific knowledge using a suitable language, (3) anchoring the collective memory of past events, (4) visualize and emotionalize the topic of natural hazards, (5) strengthening the communication between peers, and (6) highlighting local resources and knowledge. In addition to these theoretical advantages, an exhibition may fulfill the requirements of a community. In the Ubaye Valley (France), this tool was proposed by the stakeholders themselves to increase awareness and preparedness of the general public. To meet this demand, the exhibition was designed following three general topics: (1) the natural phenomena and their potential consequences on the elements at risk, (2) the management and protection measures (individual and collective) and (3) the evolution of events and knowledge throughout past up to the present and the anticipation of the future situations. Besides being a real risk communication practice, this exhibition will be the setting for an extensive research project studying the effect of the use of visualization tools on the awareness and preparedness of a community. A wide range of visuals (photos, videos, maps, models, animations, multimedia, etc.) will present many dimensions of locally occurring natural hazards and risk problems. The aim of the research is (1) to

Potent inhibition of HIV-1 replication by a Tat mutant.

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Luke W Meredith

Full Text Available Herein we describe a mutant of the two-exon HIV-1 Tat protein, termed Nullbasic, that potently inhibits multiple steps of the HIV-1 replication cycle. Nullbasic was created by replacing the entire arginine-rich basic domain of wild type Tat with glycine/alanine residues. Like similarly mutated one-exon Tat mutants, Nullbasic exhibited transdominant negative effects on Tat-dependent transactivation. However, unlike previously reported mutants, we discovered that Nullbasic also strongly suppressed the expression of unspliced and singly-spliced viral mRNA, an activity likely caused by redistribution and thus functional inhibition of HIV-1 Rev. Furthermore, HIV-1 virion particles produced by cells expressing Nullbasic had severely reduced infectivity, a defect attributable to a reduced ability of the virions to undergo reverse transcription. Combination of these inhibitory effects on transactivation, Rev-dependent mRNA transport and reverse transcription meant that permissive cells constitutively expressing Nullbasic were highly resistant to a spreading infection by HIV-1. Nullbasic and its activities thus provide potential insights into the development of potent antiviral therapeutics that target multiple stages of HIV-1 infection.

Study on the early and late mutants of radiation induced rice

International Nuclear Information System (INIS)

Yang Hefeng; Chen Xiulan; He Zhentian; Gu Shiliang; Xu Chenwu

1990-12-01

After three years of consecutive experiments for the irradiated M 2 generations of 53 different varieties of rice, the following results have been obtained: (1) The average of early mutant plant rate is 1.4%. The rate in the early-maturing varieties is lower than that in the late-maturing varieties. It is in proportion to the length of growing period of these varieties tested. The shortened days of growing period of early mutants are 3 to 32 days (the average was 9.5 days), and it is increasing as the growing period increases. (2) In the irradiated M 2 generation of same variety, the early mutants and late mutants could be simultaneously happened, but the rate of the late mutants is 2.67%, which is higher than the rate of early mutants (1.39%). The shortened and prolonged days of growing period are 11.5 and 10.5 days respectively. These early and late mutants have some changes, both good and bad, in agronomical traits such as plant height, weight per kilo-grains and grains number per tassel. In some extent these changes are significant

Officially released mutant varieties in China

International Nuclear Information System (INIS)

Liu, L.; Van Zanten, L.; Shu, Q.Y.; Maluszynski, M.

2004-01-01

The use of mutation techniques for crop improvement in China has a long and well-established tradition of more than 50 years. As the result of intensive research in many institutes dealing with application of nuclear technologies more than 620 cultivars of 44 crop species have been released. Numerous mutant varieties have been grown on a large scale bringing significant economic impact, sustaining crop production and greatly contributing to increase of food production also in stress prone areas of the country. However, there is still missing information not only on the number of mutant varieties released in particular crop species but also on mutagens applied, selection approaches and on the use of mutants in cross breeding. Numerous Chinese scientists collected and systematized this information. Results of their work were often published in local scientific journals in the Chinese language and as such were unavailable to breeders from other countries. Having this in mind, we requested Dr. Liu Luxiang, the Director of the Department of Plant Mutation Breeding and Genetics, Institute for Application of Atomic Energy, Chinese Academy of Agricultural Sciences in Beijing to help us in finding as much information as possible on mutant varieties officially released in China. The data has been collected in close collaboration with his colleagues from various institutions all over the country and then evaluated, edited and prepared for publication by our team responsible for the FAO/IAEA Database of Officially Released Mutant Varieties. We would like to thank all Chinese colleagues who contributed to this list of Chinese mutant varieties. We hope that this publication will stimulate plant breeders in China to collect more information on released mutant varieties and especially on the use of mutated genes in cross breeding. (author)

Gamma ray induced male sterility mutant in lentil

International Nuclear Information System (INIS)

Srivastava, A.; Yadav, A.K.

2001-01-01

Full text: Male sterility refers to the failure of pollen grains to bring about effective fertilization, either due to structural default or physiological disfunctioning and has special significance in hybridization programmes. Male steriles have been produced in a number of crop plants like red gram, pigeon pea, mung bean, khesari and lentil. A completely male sterile mutant was isolated in Lens culinaris Medik, after seed treatment with 100 Gy dose of gamma rays. The male sterile mutant showed 100% pollen sterility but was morphologically more vigorous than the parent plants. It showed more branches and its leaves were bigger, more oblong and dark green. The number of flowers borne by the mutant was significantly higher than any other plant of the treatment. The size of the flowers was also increased but the anthers were smaller in size. Pollen grains were few in number, round in shape but empty and did not take up any stain, indicating that normal microsporogenesis had not taken place. This male sterile mutant was used as the female parent and pollinated with pollen of a parent. Four pods with one seed in each were formed indicating that the mutant was female fertile. The seeds were smaller than those of the parent variety and also dark coloured. The mutant showed increased vigour and flower number as compared to parental plants. Lentil is an important pulse crop and induction of variability in its germplasm is necessary for its improvement. Male steriles can be used conveniently in lentil hybridization programmes. (author)

Engineering of plants with improved properties as biofuels feedstocks by vessel-specific complementation of xylan biosynthesis mutants

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Petersen Pia Damm

2012-11-01

Full Text Available Abstract Background Cost-efficient generation of second-generation biofuels requires plant biomass that can easily be degraded into sugars and further fermented into fuels. However, lignocellulosic biomass is inherently recalcitrant toward deconstruction technologies due to the abundant lignin and cross-linked hemicelluloses. Furthermore, lignocellulosic biomass has a high content of pentoses, which are more difficult to ferment into fuels than hexoses. Engineered plants with decreased amounts of xylan in their secondary walls have the potential to render plant biomass a more desirable feedstock for biofuel production. Results Xylan is the major non-cellulosic polysaccharide in secondary cell walls, and the xylan deficient irregular xylem (irx mutants irx7, irx8 and irx9 exhibit severe dwarf growth phenotypes. The main reason for the growth phenotype appears to be xylem vessel collapse and the resulting impaired transport of water and nutrients. We developed a xylan-engineering approach to reintroduce xylan biosynthesis specifically into the xylem vessels in the Arabidopsis irx7, irx8 and irx9 mutant backgrounds by driving the expression of the respective glycosyltransferases with the vessel-specific promoters of the VND6 and VND7 transcription factor genes. The growth phenotype, stem breaking strength, and irx morphology was recovered to varying degrees. Some of the plants even exhibited increased stem strength compared to the wild type. We obtained Arabidopsis plants with up to 23% reduction in xylose levels and 18% reduction in lignin content compared to wild-type plants, while exhibiting wild-type growth patterns and morphology, as well as normal xylem vessels. These plants showed a 42% increase in saccharification yield after hot water pretreatment. The VND7 promoter yielded a more complete complementation of the irx phenotype than the VND6 promoter. Conclusions Spatial and temporal deposition of xylan in the secondary cell wall of

Altered metabolism of growth hormone receptor mutant mice: a combined NMR metabonomics and microarray study.

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Horst Joachim Schirra

Full Text Available BACKGROUND: Growth hormone is an important regulator of post-natal growth and metabolism. We have investigated the metabolic consequences of altered growth hormone signalling in mutant mice that have truncations at position 569 and 391 of the intracellular domain of the growth hormone receptor, and thus exhibit either low (around 30% maximum or no growth hormone-dependent STAT5 signalling respectively. These mutations result in altered liver metabolism, obesity and insulin resistance. METHODOLOGY/PRINCIPAL FINDINGS: The analysis of metabolic changes was performed using microarray analysis of liver tissue and NMR metabonomics of urine and liver tissue. Data were analyzed using multivariate statistics and Gene Ontology tools. The metabolic profiles characteristic for each of the two mutant groups and wild-type mice were identified with NMR metabonomics. We found decreased urinary levels of taurine, citrate and 2-oxoglutarate, and increased levels of trimethylamine, creatine and creatinine when compared to wild-type mice. These results indicate significant changes in lipid and choline metabolism, and were coupled with increased fat deposition, leading to obesity. The microarray analysis identified changes in expression of metabolic enzymes correlating with alterations in metabolite concentration both in urine and liver. Similarity of mutant 569 to the wild-type was seen in young mice, but the pattern of metabolites shifted to that of the 391 mutant as the 569 mice became obese after six months age. CONCLUSIONS/SIGNIFICANCE: The metabonomic observations were consistent with the parallel analysis of gene expression and pathway mapping using microarray data, identifying metabolites and gene transcripts involved in hepatic metabolism, especially for taurine, choline and creatinine metabolism. The systems biology approach applied in this study provides a coherent picture of metabolic changes resulting from impaired STAT5 signalling by the growth hormone

Comprehensive behavioral analysis of ENU-induced Disc1-Q31L and -L100P mutant mice

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Shoji Hirotaka

2012-02-01

Full Text Available Abstract Background Disrupted-in-Schizophrenia 1 (DISC1 is considered to be a candidate susceptibility gene for psychiatric disorders, including schizophrenia, bipolar disorder, and major depression. A recent study reported that N-ethyl-N-nitrosourea (ENU-induced mutations in exon 2 of the mouse Disc1 gene, which resulted in the amino acid exchange of Q31L and L100P, caused an increase in depression-like behavior in 31 L mutant mice and schizophrenia-like behavior in 100P mutant mice; thus, these are potential animal models of psychiatric disorders. However, remaining heterozygous mutations that possibly occur in flanking genes other than Disc1 itself might induce behavioral abnormalities in the mutant mice. Here, to confirm the effects of Disc1-Q31L and Disc1-L100P mutations on behavioral phenotypes and to investigate the behaviors of the mutant mice in more detail, the mutant lines were backcrossed to C57BL/6JJcl through an additional two generations and the behaviors were analyzed using a comprehensive behavioral test battery. Results Contrary to expectations, 31 L mutant mice showed no significant behavioral differences when compared with wild-type control mice in any of the behavioral tests, including the Porsolt forced swim and tail suspension tests, commonly used tests for depression-like behavior. Also, 100P mutant mice exhibited no differences in almost all of the behavioral tests, including the prepulse inhibition test for measuring sensorimotor gating, which is known to be impaired in schizophrenia patients; however, 100P mutant mice showed higher locomotor activity compared with wild-type control mice in the light/dark transition test. Conclusions Although these results are partially consistent with the previous study in that there was hyperactivity in 100P mutant mice, the vast majority of the results are inconsistent with those of the previous study; this discrepancy may be explained by differences in the genetic background of the

Comparative study on nutritional quality and application value in three mutants of indigofera pseudotinctoria mats

International Nuclear Information System (INIS)

Mei Shufang; Mei Zhong; Zhao Hua; Huang Xin; Ye Hongxia; Shu Xiaoli; Wu Dianxing

2013-01-01

Major nutritional quality and values in purple-leaf, yellow-leaf and high flavone mutants of Indigofera pseudotinctoria Mats were investigated compared with the wild type. The content of protein in leaves of high flavone mutant was 26.45%, 24.31% higher than that of the wild type. The content of fiber in high flavone mutant was 18.92% lower than that of the wild type. The contents of Fe, Cu, Mn, Zn in high flavone mutant were increased by 72.34% , 7.02%, 21.01% and 38.75%, respectively. Contents of TAA and EAA in high flavone mutant were increase by 27.85% and 27.68%, respectively. The contents of protein in purple- and yellow-leaf mutants were lower than that of the wild types, and the contents of Ca in purple- and yellow-leaf mutants were increased by 15.22% and 25.46%. The results above indicated that high flavone mutant had high application values used as feed crop, while purple- and yellow-leaf mutants also had feeding values to some extent. (authors)

Functional rescue of mutant ABCA1 proteins by sodium 4-phenylbutyrate.

Science.gov (United States)

Sorrenson, Brie; Suetani, Rachel J; Williams, Michael J A; Bickley, Vivienne M; George, Peter M; Jones, Gregory T; McCormick, Sally P A

2013-01-01

Mutations in the ATP-binding cassette transporter A1 (ABCA1) are a major cause of decreased HDL cholesterol (HDL-C), which infers an increased risk of cardiovascular disease (CVD). Many ABCA1 mutants show impaired localization to the plasma membrane. The aim of this study was to investigate whether the chemical chaperone, sodium 4-phenylbutyrate (4-PBA) could improve cellular localization and function of ABCA1 mutants. Nine different ABCA1 mutants (p.A594T, p.I659V, p.R1068H, p.T1512M, p.Y1767D, p.N1800H, p.R2004K, p.A2028V, p.Q2239N) expressed in HEK293 cells, displaying different degrees of mislocalization to the plasma membrane and discrete impacts on cholesterol efflux, were subject to treatment with 4-PBA. Treatment restored localization to the plasma membrane and increased cholesterol efflux function for the majority of mutants. Treatment with 4-PBA also increased ABCA1 protein expression in all transfected cell lines. In fibroblast cells obtained from low HDL-C subjects expressing two of the ABCA1 mutants (p.R1068H and p.N1800H), 4-PBA increased cholesterol efflux without any increase in ABCA1 expression. Our study is the first to investigate the effect of the chemical chaperone, 4-PBA on ABCA1 and shows that it is capable of restoring plasma membrane localization and enhancing the cholesterol efflux function of mutant ABCA1s both in vitro and ex vivo. These results suggest 4-PBA may warrant further investigation as a potential therapy for increasing cholesterol efflux and HDL-C levels.

[Substrate specificities of bile salt hydrolase 1 and its mutants from Lactobacillus salivarius].

Science.gov (United States)

Bi, Jie; Fang, Fang; Qiu, Yuying; Yang, Qingli; Chen, Jian

2014-03-01

In order to analyze the correlation between critical residues in the catalytic centre of BSH and the enzyme substrate specificity, seven mutants of Lactobacillus salivarius bile salt hydrolase (BSH1) were constructed by using the Escherichia coli pET-20b(+) gene expression system, rational design and site-directed mutagenesis. These BSH1 mutants exhibited different hydrolytic activities against various conjugated bile salts through substrate specificities comparison. Among the residues being tested, Cys2 and Thr264 were deduced as key sites for BSH1 to catalyze taurocholic acid and glycocholic acid, respectively. Moreover, Cys2 and Thr264 were important for keeping the catalytic activity of BSH1. The high conservative Cys2 was not the only active site, other mutant amino acid sites were possibly involved in substrate binding. These mutant residues might influence the space and shape of the substrate-binding pockets or the channel size for substrate passing through and entering active site of BSH1, thus, the hydrolytic activity of BSH1 was changed to different conjugated bile salt.

Matching NLR Immune Receptors to Autoimmunity in camta3 Mutants Using Antimorphic NLR Alleles

DEFF Research Database (Denmark)

Lolle, Signe; Greeff, Christiaan; Petersen, Klaus

2017-01-01

result from inappropriate NLR activation because mutations in plant guardees could trigger corresponding NLR guards. To explore these hypotheses, we expressed 108 dominant-negative (DN) Arabidopsis NLRs in various lesion mimic mutants, including camta3, which exhibits autoimmunity. CAMTA3 was previously...

Programmed cell death in the leaves of the Arabidopsis spontaneous necrotic spots (sns-D mutant correlates with increased expression of the eukaryotic translation initiation factor eIF4B2

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Gwenael M.D.J.-M. Gaussand

2011-04-01

Full Text Available From a pool of transgenic Arabidopsis (Arabidopsis thaliana plants harboring an activator T-DNA construct, one mutant was identified that developed spontaneous necrotic spots (sns-D on the rosette leaves under aseptic conditions. The sns-D mutation is dominant and homozygous plants are embryo lethal. The mutant produced smaller rosettes with a different number of stomata than the wild-type. DNA fragmentation in the nuclei of cells in the necrotic spots and a significant increase of caspase-3 and caspase-6 like activities in sns-D leaf extracts indicated that the sns-D mutation caused programmed cell death (PCD. The integration of the activator T-DNA caused an increase of the expression level of At1g13020, which encodes the eukaryotic translation initiation factor eIF4B2. The expression level of eIF4B2 was positively correlated with the severity of sns-D mutant phenotype. Overexpression of the eIF4B2 cDNA mimicked phenotypic traits of the sns-D mutant indicating that the sns-D mutant phenotype is indeed caused by activation tagging of eIF4B2. Thus, incorrect regulation of translation initiation may result in PCD.

Seed protein and nitrogen fixation in chickpea mutant variety Hyprosola

Energy Technology Data Exchange (ETDEWEB)

Schroeder, H E; Gibson, A H; Oram, R N [CSIRO, Division of Plant Industry, Canberra ACT (Australia); Shaikh, M A.Q. [Bangladesh Institute of Nuclear Agriculture, Mymensingh (Bangladesh)

1989-01-01

Full text: 'Hyprosola' is a high yielding, high protein mutant cultivar obtained after gamma irradiation from the variety 'Faridpur-1'. The mutant yields 45 % more protein per unit area. The essential amino acid index is unchanged. It is likely that the high nutritional value in 'Hyprosola' seed protein arises from an increase in the albumin:globulin ratio. Nitrogen fixation rates of the mutant during the first 7 weeks of growth were found to be similar to 'Faridpur-1'. Under field conditions, the mutant may be able to nodulate more rapidly and more extensively than the parent variety. (author)

Genomic data reveal Toxoplasma gondii differentiation mutants are also impaired with respect to switching into a novel extracellular tachyzoite state.

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Pamela J Lescault

2010-12-01

Full Text Available Toxoplasma gondii pathogenesis includes the invasion of host cells by extracellular parasites, replication of intracellular tachyzoites, and differentiation to a latent bradyzoite stage. We present the analysis of seven novel T. gondii insertional mutants that do not undergo normal differentiation to bradyzoites. Microarray quantification of the variation in genome-wide RNA levels for each parasite line and times after induction allowed us to describe states in the normal differentiation process, to analyze mutant lines in the context of these states, and to identify genes that may have roles in initiating the transition from tachyzoite to bradyzoite. Gene expression patterns in wild-type parasites undergoing differentiation suggest a novel extracellular state within the tachyzoite stage. All mutant lines exhibit aberrant regulation of bradyzoite gene expression and notably some of the mutant lines appear to exhibit high proportions of the intracellular tachyzoite state regardless of whether they are intracellular or extracellular. In addition to the genes identified by the insertional mutagenesis screen, mixture model analysis allowed us to identify a small number of genes, in mutants, for which expression patterns could not be accounted for using the three parasite states--genes that may play a mechanistic role in switching from the tachyzoite to bradyzoite stage.

Cancer cells recovering from damage exhibit mitochondrial restructuring and increased aerobic glycolysis

Energy Technology Data Exchange (ETDEWEB)

Akakura, Shin; Ostrakhovitch, Elena; Sanokawa-Akakura, Reiko [Frontiers in Bioscience Research Institute in Aging and Cancer, University of California, Irvine, CA (United States); Tabibzadeh, Siamak, E-mail: fbs@bioscience.org [Frontiers in Bioscience Research Institute in Aging and Cancer, University of California, Irvine, CA (United States); Dept of Oncologic Radiology, University of California, Irvine, CA (United States)

2014-06-13

Highlights: • Some cancer cells recover from severe damage that causes cell death in majority of cells. • Damage-Recovered (DR) cancer cells show reduced mitochondria, mDNA and mitochondrial enzymes. • DR cells show increased aerobic glycolysis, ATP, cell proliferation, and resistance to damage. • DR cells recovered from in vivo damage also show increased glycolysis and proliferation rate. - Abstract: Instead of relying on mitochondrial oxidative phosphorylation, most cancer cells rely heavily on aerobic glycolysis, a phenomenon termed as “the Warburg effect”. We considered that this effect is a direct consequence of damage which persists in cancer cells that recover from damage. To this end, we studied glycolysis and rate of cell proliferation in cancer cells that recovered from severe damage. We show that in vitro Damage-Recovered (DR) cells exhibit mitochondrial structural remodeling, display Warburg effect, and show increased in vitro and in vivo proliferation and tolerance to damage. To test whether cancer cells derived from tumor microenvironment can show similar properties, we isolated Damage-Recovered (T{sup DR}) cells from tumors. We demonstrate that T{sup DR} cells also show increased aerobic glycolysis and a high proliferation rate. These findings show that Warburg effect and its consequences are induced in cancer cells that survive severe damage.

Characterization of a mutant of Escherichia coli B/R defective in mutation frequency decline

International Nuclear Information System (INIS)

George, D.L.

1974-01-01

A mutant of Escherichia coli B/r designated mfd is very deficient in the ability to exhibit mutation frequency decline (MFD), the characteristic loss of potential suppressor mutations which occurs when protein synthesis is briefly inhibited after irradiation with ultraviolet light (uv). This mutant is known to excise pyrimidine dimers very slowly, although it is as uv-resistant as its mfd + B/r parent strain. We have found that the mfd mutant performs the initial incision step of excision repair normally, but repairs the resulting single-strand breaks much more slowly than the mfd + strain. In spite of the slow dimer excision in the mfd mutant, single-strand DNA breaks do not accumulate during postirradiation incubation, implying that incision and excision are well corrdinated. the prolonged postirradiation lag in cell division and DNA synthesis which accompany slow excision in the mfd strain indicates that resumption of these processes of optimal rates is linked to the timing of excision repair. The normal uv-resistance of the mfd mutant also suggests such coordination and shows that the rate of excision repair is independent of its ultimate efficiency in the removal of potentially lethal uv-induced damage. (U.S.)

MT-ND5 Mutation Exhibits Highly Variable Neurological Manifestations at Low Mutant Load

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Yi Shiau Ng

2018-04-01

Full Text Available Mutations in the m.13094T>C MT-ND5 gene have been previously described in three cases of Leigh Syndrome (LS. In this retrospective, international cohort study we identified 20 clinically affected individuals (13 families and four asymptomatic carriers. Ten patients were deceased at the time of analysis (median age of death was 10 years (range: 5·4 months−37 years, IQR = 17·9 years. Nine patients manifested with LS, one with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS, and one with Leber hereditary optic neuropathy. The remaining nine patients presented with either overlapping syndromes or isolated neurological symptoms. Mitochondrial respiratory chain activity analysis was normal in five out of ten muscle biopsies. We confirmed maternal inheritance in six families, and demonstrated marked variability in tissue segregation, and phenotypic expression at relatively low blood mutant loads. Neuropathological studies of two patients manifesting with LS/MELAS showed prominent capillary proliferation, microvacuolation and severe neuronal cell loss in the brainstem and cerebellum, with conspicuous absence of basal ganglia involvement. These findings suggest that whole mtDNA genome sequencing should be considered in patients with suspected mitochondrial disease presenting with complex neurological manifestations, which would identify over 300 known pathogenic variants including the m.13094T>C. Keywords: Mitochondrial encephalomyopathy, Lactic acidosis and stroke-like episodes (MELAS, Leigh syndrome (LS, Mitochondrial DNA, Heteroplasmy, Neuropathology

Prevention of GABA reduction during dough fermentation using a baker's yeast dal81 mutant.

Science.gov (United States)

Ando, Akira; Nakamura, Toshihide

2016-10-01

γ-Aminobutyric acid (GABA) is consumed by yeasts during fermentation. To prevent GABA reduction in bread dough, a baker's yeast mutant AY77 deficient in GABA assimilation was characterized and utilized for wheat dough fermentation. An amber mutation in the DAL81 gene, which codes for a positive regulator of multiple nitrogen degradation pathways, was found in the AY77 strain. The qPCR analyses of genes involved in nitrogen utilization showed that transcriptional levels of the UGA1 and DUR3 genes encoding GABA transaminase and urea transporter, respectively, are severely decreased in the AY77 cells. The AY77 strain cultivated by fed-batch culture using cane molasses exhibited inferior gas production during dough fermentation compared to that of wild-type strain AY13. However, when fed with molasses containing 0.5% ammonium sulfate, the mutant strain exhibited gas production comparable to that of the AY13 strain. In contrast to the AY13 strain, which completely consumed GABA in dough within 5 h, the AY77 strain consumed no GABA under either culture condition. Dough fermentation with the dal81 mutant strain should be useful for suppression of GABA reduction in breads. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Isolation and Characterization of a Catabolite Repression-Insensitive Mutant of a Methanol Yeast, Candida boidinii A5, Producing Alcohol Oxidase in Glucose-Containing Medium

OpenAIRE

Sakai, Yasuyoshi; Sawai, Tohru; Tani, Yoshiki

1987-01-01

Mutants exhibiting alcohol oxidase (EC 1.1.3.13) activity when grown on glucose in the presence of methanol were found among 2-deoxyglucose-resistant mutants derived from a methanol yeast, Candida boidinii A5. One of these mutants, strain ADU-15, showed the highest alcohol oxidase activity in glucose-containing medium. The growth characteristics and also the induction and degradation of alcohol oxidase were compared with the parent strain and mutant strain ADU-15. In the parent strain, initia...

Steady-state fluorescence and phosphorescence spectroscopic studies of bacterial luciferase tryptophan mutants.

Science.gov (United States)

Li, Z; Meighen, E A

1994-09-01

Bacterial luciferase, which catalyzes the bioluminescence reaction in luminous bacteria, consists of two nonidentical polypeptides, α and β. Eight mutants of luciferase with each of the tryptophans replaced by tyrosine were generated by site-directed mutagenesis and purified to homogeneity. The steady-state tryptophan fluorescence and low-temperature phosphorescence spectroscopic properties of these mutants were characterized. In some instances, mutation of only a single tryptophan residue resulted in large spectral changes. The tryptophan residues conserved in both the α and the β subunits exhibited distinct fluorescence emission properties, suggesting that these tryptophans have different local enviroments. The low-temperature phosphorescence data suggest that the tryptophans conserved in bot the α and the β subunits are not located at the subunit interface and/or involved in subunit interactions. The differences in the spectral properties of the mutants have provided useful information on the local environment of the individual tryptophan residues as well as on the quaternary structure of the protein.

The agronomic characters of a high protein rice mutant

International Nuclear Information System (INIS)

Harn, C.; Won, J.L.; Choi, K.T.

1975-01-01

Mutant lines (M 5 -M 9 ) of macro-phenotypic traits from several varieties were screened for the protein content. Mutant 398 (M 9 ) is one of the high protein mutants selected from Hokwang. Three years' tests revealed that it has a high protein line under any condition of cultivation. Except for early maturity and short culmness, other agronomic and yield characters were similar to the original variety. There was no difference between the mutant 398 and its mother variety in grain shape and weight, and also the size and protein content of the embryo. The high protein content of the mutant is attributable to the increase of protein in the endosperm. About 150 normal-looking or a few days-earlier-maturing selections were made from Jinheung variety in the M 3 and screened for protein. Promising lines in terms of the plant type, yield and protein were obtained. (author)

Semi-dwarf mutants in triticale and wheat breeding

International Nuclear Information System (INIS)

Driscoll, C.J.

1984-01-01

The triticale lines Beagle and DR-IRA have been subjected to ionizing irradiation and chemical mutagenesis in order to produce semi-dwarf mutants. Beagle is 100 cm tall and DR-IRA 80 cm under average field conditions. A bulk then pedigree method is currently represented by 158 single plots of M 6 (or in some cases M 7 ) mutants that are from 5 to 35 cm shorter than the control variety. The shortest mutants are 65 cm in height. Forty of these mutants are also earlier flowering than the control varieties. Replicated yield testing will be conducted on confirmed mutants in 1983. Response to gibberellic acid of these mutants will also be determined. The Cornerstone male-sterility mutant (ms1c) on chromosome arm 4Aα has been combined with the GA-insensitive/reduced height gene Gai/Rht1 which is also on chromosome arm 4Aα. The ms1c mutant has also been combined with Gai/Rht2 on chromosome 4D and with both Gai/Rht1 and Gai/Rht2. The combination ms1c and Gai/Rht1 has been chosen as the basis of a composite cross. Thirteen varieties were tested with GA 3 and seven (Warigal, Aroona, Oxley, Banks, Avocet, Matipo and Toquifen) which contain Gai/Rht1 were crossed with ms1c Gai/Rht1 and entered into an interpollinating F 2 . The entire composite is homozygous for this semi-dwarf allele and selection will be practiced for increased height on a GA-insensitive background. (author)

An extra early mutant of pigeonpea

International Nuclear Information System (INIS)

Ravikesavan, R.; Kalaimagal, T.; Rathnaswamy, R.

2001-01-01

The redgram (Cajanus cajan (L.) Huth) variety 'Prabhat DT' was gamma irradiated with 100, 200, 300 and 400 Gy doses. Several mutants have been identified viz., extra early mutants, monostem mutants, obcordifoliate mutants and bi-stigmatic mutants. The extra early mutant was obtained when treated with 100 Gy dose. The mutant was selfed and forwarded from M 2 to M 4 generation. In the M 4 generation the mutant line was raised along with the parental variety. Normal cultural practices were followed and the biometrical observations were recorded. It was observed that for the characters viz., total number of branches per plant, number of pods per plants, seeds per pod, 100 seed weight and seed yield per plant there was no difference between the mutant and parent variety. Whereas, regarding the days to flowering and maturity the mutants were earlier than the parents. The observation was recorded from two hundred plants each. The mutant gives the same yield in 90 days as that of the parent variety in 107 days, which make it an economic mutant

Fusion genetic analysis of jasmonate-signalling mutants in Arabidopsis

DEFF Research Database (Denmark)

Jensen, Anders Bøgh; Raventos, D.; Mundy, John Williams

2002-01-01

as two recessive mutants, designated joe1 and 2, that overexpress the reporter. Genetic analysis indicated that reporter overexpression in the joe mutants requires COI. joe1 responded to MeJA with increased anthocyanin accumulation, while joe2 responded with decreased root growth inhibition. In addition...... activity was also induced by the protein kinase inhibitor staurosporine and antagonized by the protein phosphatase inhibitor okadaic acid. FLUC bio-imaging, RNA gel-blot analysis and progeny analyses identified three recessive mutants that underexpress the FLUC reporter, designated jue1, 2 and 3, as well...

Normal aging modulates the neurotoxicity of mutant huntingtin.

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Elsa Diguet

Full Text Available Aging likely plays a role in neurodegenerative disorders. In Huntington's disease (HD, a disorder caused by an abnormal expansion of a polyglutamine tract in the protein huntingtin (Htt, the role of aging is unclear. For a given tract length, the probability of disease onset increases with age. There are mainly two hypotheses that could explain adult onset in HD: Either mutant Htt progressively produces cumulative defects over time or "normal" aging renders neurons more vulnerable to mutant Htt toxicity. In the present study, we directly explored whether aging affected the toxicity of mutant Htt in vivo. We studied the impact of aging on the effects produced by overexpression of an N-terminal fragment of mutant Htt, of wild-type Htt or of a beta-Galactosidase (beta-Gal reporter gene in the rat striatum. Stereotaxic injections of lentiviral vectors were performed simultaneously in young (3 week and old (15 month rats. Histological evaluation at different time points after infection demonstrated that the expression of mutant Htt led to pathological changes that were more severe in old rats, including an increase in the number of small Htt-containing aggregates in the neuropil, a greater loss of DARPP-32 immunoreactivity and striatal neurons as assessed by unbiased stereological counts.The present results support the hypothesis that "normal" aging is involved in HD pathogenesis, and suggest that age-related cellular defects might constitute potential therapeutic targets for HD.

Expression of ALS/FTD-linked mutant CCNF in zebrafish leads to increased cell death in the spinal cord and an aberrant motor phenotype.

Science.gov (United States)

Hogan, Alison L; Don, Emily K; Rayner, Stephanie L; Lee, Albert; Laird, Angela S; Watchon, Maxinne; Winnick, Claire; Tarr, Ingrid S; Morsch, Marco; Fifita, Jennifer A; Gwee, Serene S L; Formella, Isabel; Hortle, Elinor; Yuan, Kristy C; Molloy, Mark P; Williams, Kelly L; Nicholson, Garth A; Chung, Roger S; Blair, Ian P; Cole, Nicholas J

2017-07-15

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, fatal neurodegenerative disease characterised by the death of upper and lower motor neurons. Approximately 10% of cases have a known family history of ALS and disease-linked mutations in multiple genes have been identified. ALS-linked mutations in CCNF were recently reported, however the pathogenic mechanisms associated with these mutations are yet to be established. To investigate possible disease mechanisms, we developed in vitro and in vivo models based on an ALS-linked missense mutation in CCNF. Proteomic analysis of the in vitro models identified the disruption of several cellular pathways in the mutant model, including caspase-3 mediated cell death. Transient overexpression of human CCNF in zebrafish embryos supported this finding, with fish expressing the mutant protein found to have increased levels of cleaved (activated) caspase-3 and increased cell death in the spinal cord. The mutant CCNF fish also developed a motor neuron axonopathy consisting of shortened primary motor axons and increased frequency of aberrant axonal branching. Importantly, we demonstrated a significant correlation between the severity of the CCNF-induced axonopathy and a reduced motor response to a light stimulus (photomotor response). This is the first report of an ALS-linked CCNF mutation in vivo and taken together with the in vitro model identifies the disruption of cell death pathways as a significant consequence of this mutation. Additionally, this study presents a valuable new tool for use in ongoing studies investigating the pathobiology of ALS-linked CCNF mutations. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The phenotype of FancB-mutant mouse embryonic stem cells

International Nuclear Information System (INIS)

Kim, Tae Moon; Ko, Jun Ho; Choi, Yong Jun; Hu Lingchuan; Hasty, Paul

2011-01-01

Fanconi anemia (FA) is a rare autosomal recessive disease characterized by bone marrow failure, developmental defects and cancer. There are multiple FA genes that enable the repair of interstrand crosslinks (ICLs) in coordination with a variety of other DNA repair pathways in a way that is poorly understood. Here we present the phenotype of mouse embryonic stem (ES) cells mutated for FancB. We found FancB-mutant cells exhibited reduced cellular proliferation, hypersensitivity to the crosslinking agent mitomycin C (MMC), increased spontaneous and MMC-induced chromosomal abnormalities, reduced spontaneous sister chromatid exchanges (SCEs), reduced gene targeting, reduced MMC-induced Rad51 foci and absent MMC-induced FancD2 foci. Since FancB is on the X chromosome and since ES cells are typically XY, FancB is an excellent target for an epistatic analysis to elucidate FA's role in ICL repair.

Sorghum Brown Midrib Mutants, Tools to Improve Biomass for Biofuels

Science.gov (United States)

To improve sorghum for cellulosic bioenergy uses, brown midrib mutants are being investigated for their ability to increase the conversion efficiency of biomass. brown midrib 6 and 12 (bmr6 and 12) mutants affect monolignol biosynthesis resulting in reduced lignin content and altered lignin composi...

Phage Pl mutants with altered transducing abilities for Escherichia coli

International Nuclear Information System (INIS)

Wall, J.D.; Harriman, P.D.

1974-01-01

A search was made for mutants of the coliphage P1 with altered transducing frequencies. A method was developed for the rapid assay of transducing frequencies in single plaques using prophage lambda as the transduced bacterial marker. This procedure selects for mutants altered in their ability to package host DNA. Mutants with 5 to 10 times higher or 10 to 20 times lower frequencies than those of wild-type P1 were found. Not only are the markers used for the detection of the mutants affected, but all other markers are similarly affected (not always to the same extent). One of the high transducing frequency mutants is a suppressible amber, indicating that loss of a function increases P1's ability to package host DNA preferentially. (U.S.)

klf2ash317 Mutant Zebrafish Do Not Recapitulate Morpholino-Induced Vascular and Haematopoietic Phenotypes.

Directory of Open Access Journals (Sweden)

Peter Novodvorsky

Full Text Available The zinc-finger transcription factor Krϋppel-like factor 2 (KLF2 transduces blood flow into molecular signals responsible for a wide range of responses within the vasculature. KLF2 maintains a healthy, quiescent endothelial phenotype. Previous studies report a range of phenotypes following morpholino antisense oligonucleotide-induced klf2a knockdown in zebrafish. Targeted genome editing is an increasingly applied method for functional assessment of candidate genes. We therefore generated a stable klf2a mutant zebrafish and characterised its cardiovascular and haematopoietic development.Using Transcription Activator-Like Effector Nucleases (TALEN we generated a klf2a mutant (klf2ash317 with a 14bp deletion leading to a premature stop codon in exon 2. Western blotting confirmed loss of wild type Klf2a protein and the presence of a truncated protein in klf2ash317 mutants. Homozygous klf2ash317 mutants exhibit no defects in vascular patterning, survive to adulthood and are fertile, without displaying previously described morphant phenotypes such as high-output cardiac failure, reduced haematopoetic stem cell (HSC development or impaired formation of the 5th accessory aortic arch. Homozygous klf2ash317 mutation did not reduce angiogenesis in zebrafish with homozygous mutations in von Hippel Lindau (vhl, a form of angiogenesis that is dependent on blood flow. We examined expression of three klf family members in wildtype and klf2ash317 zebrafish. We detected vascular expression of klf2b (but not klf4a or biklf/klf4b/klf17 in wildtypes but found no differences in expression that might account for the lack of phenotype in klf2ash317 mutants. klf2b morpholino knockdown did not affect heart rate or impair formation of the 5th accessory aortic arch in either wildtypes or klf2ash317 mutants.The klf2ash317 mutation produces a truncated Klf2a protein but, unlike morpholino induced klf2a knockdown, does not affect cardiovascular development.

Analysis of Lysophospholipid Content in Low Phytate Rice Mutants.

Science.gov (United States)

Tong, Chuan; Chen, Yaling; Tan, Yuanyuan; Liu, Lei; Waters, Daniel L E; Rose, Terry J; Shu, Qingyao; Bao, Jinsong

2017-07-05

As a fundamental component of nucleic acids, phospholipids, and adenosine triphosphate, phosphorus (P) is critical to all life forms, however, the molecular mechanism of P translocation and distribution in rice grains are still not understood. Here, with the use of five different low phytic acid (lpa) rice mutants, the redistribution in the main P-containing compounds in rice grain, phytic acid (PA), lysophospholipid (LPL), and inorganic P (Pi), was investigated. The lpa mutants showed a significant decrease in PA and phytate-phosphorus (PA-P) concentration with a concomitant increase in Pi concentration. Moreover, defects in the OsST and OsMIK genes result in a great reduction of specific LPL components and LPL-phosphorus (LPL-P) contents in rice grain. In contrast, defective OsMRP5 and Os2-PGK genes led to a significant increase in individual LPL components. The effect of the Os2-PGK gene on the LPL accumulation was validated using breeding lines derived from a cross between KBNT-lpa (Os2-PGK mutation) and Jiahe218. This study demonstrates that these rice lpa mutants lead to the redistribution of Pi in endosperm and modify LPL biosynthesis. Increase LPLs in the endosperm in the lpa mutants may have practical applications in rice breeding to produce "healthier" rice.

Increasing the thermal stability of cellulase C using rules learned from thermophilic proteins: a pilot study.

Science.gov (United States)

Németh, Attila; Kamondi, Szilárd; Szilágyi, András; Magyar, Csaba; Kovári, Zoltán; Závodszky, Péter

2002-05-02

Some structural features underlying the increased thermostability of enzymes from thermophilic organisms relative to their homologues from mesophiles are known from earlier studies. We used cellulase C from Clostridium thermocellum to test whether thermostability can be increased by mutations designed using rules learned from thermophilic proteins. Cellulase C has a TIM barrel fold with an additional helical subdomain. We designed and produced a number of mutants with the aim to increase its thermostability. Five mutants were designed to create new electrostatic interactions. They all retained catalytic activity but exhibited decreased thermostability relative to the wild-type enzyme. Here, the stabilizing contributions are obviously smaller than the destabilization caused by the introduction of the new side chains. In another mutant, the small helical subdomain was deleted. This mutant lost activity but its melting point was only 3 degrees C lower than that of the wild-type enzyme, which suggests that the subdomain is an independent folding unit and is important for catalytic function. A double mutant was designed to introduce a new disulfide bridge into the enzyme. This mutant is active and has an increased stability (deltaT(m)=3 degrees C, delta(deltaG(u))=1.73 kcal/mol) relative to the wild-type enzyme. Reduction of the disulfide bridge results in destabilization and an altered thermal denaturation behavior. We conclude that rules learned from thermophilic proteins cannot be used in a straightforward way to increase the thermostability of a protein. Creating a crosslink such as a disulfide bond is a relatively sure-fire method but the stabilization may be smaller than calculated due to coupled destabilizing effects.

Genetic background of Prop1(df) mutants provides remarkable protection against hypothyroidism-induced hearing impairment.

Science.gov (United States)

Fang, Qing; Giordimaina, Alicia M; Dolan, David F; Camper, Sally A; Mustapha, Mirna

2012-04-01

Hypothyroidism is a cause of genetic and environmentally induced deafness. The sensitivity of cochlear development and function to thyroid hormone (TH) mandates understanding TH action in this sensory organ. Prop1(df) and Pou1f1(dw) mutant mice carry mutations in different pituitary transcription factors, each resulting in pituitary thyrotropin deficiency. Despite the same lack of detectable serum TH, these mutants have very different hearing abilities: Prop1(df) mutants are mildly affected, while Pou1f1(dw) mutants are completely deaf. Genetic studies show that this difference is attributable to the genetic backgrounds. Using embryo transfer, we discovered that factors intrinsic to the fetus are the major contributor to this difference, not maternal effects. We analyzed Prop1(df) mutants to identify processes in cochlear development that are disrupted in other hypothyroid animal models but protected in Prop1(df) mutants by the genetic background. The development of outer hair cell (OHC) function is delayed, but Prestin and KCNQ4 immunostaining appear normal in mature Prop1(df) mutants. The endocochlear potential and KCNJ10 immunostaining in the stria vascularis are indistinguishable from wild type, and no differences in neurofilament or synaptophysin staining are evident in Prop1(df) mutants. The synaptic vesicle protein otoferlin normally shifts expression from OHC to IHC as temporary afferent fibers beneath the OHC regress postnatally. Prop1(df) mutants exhibit persistent, abnormal expression of otoferlin in apical OHC, suggesting delayed maturation of synaptic function. Thus, the genetic background of Prop1(df) mutants is remarkably protective for most functions affected in other hypothyroid mice. The Prop1(df) mutant is an attractive model for identifying the genes that protect against deafness.

Proteomic analysis of the flooding tolerance mechanism in mutant soybean.

Science.gov (United States)

Komatsu, Setsuko; Nanjo, Yohei; Nishimura, Minoru

2013-02-21

Flooding stress of soybean is a serious problem because it reduces growth; however, flooding-tolerant cultivars have not been identified. To analyze the flooding tolerance mechanism of soybean, the flooding-tolerant mutant was isolated and analyzed using a proteomic technique. Flooding-tolerance tests were repeated five times using gamma-ray irradiated soybeans, whose root growth (M6 stage) was not suppressed even under flooding stress. Two-day-old wild-type and mutant plants were subjected to flooding stress for 2days, and proteins were identified using a gel-based proteomic technique. In wild-type under flooding stress, levels of proteins related to development, protein synthesis/degradation, secondary metabolism, and the cell wall changed; however, these proteins did not markedly differ in the mutant. In contrast, an increased number of fermentation-related proteins were identified in the mutant under flooding stress. The root tips of mutant plants were not affected by flooding stress, even though the wild-type plants had damaged root. Alcohol dehydrogenase activity in the mutant increased at an early stage of flooding stress compared with that of the wild-type. Taken together, these results suggest that activation of the fermentation system in the early stages of flooding may be an important factor for the acquisition of flooding tolerance in soybean. Copyright © 2012 Elsevier B.V. All rights reserved.

Glutathione-deficient Plasmodium berghei parasites exhibit growth delay and nuclear DNA damage.

Science.gov (United States)

Padín-Irizarry, Vivian; Colón-Lorenzo, Emilee E; Vega-Rodríguez, Joel; Castro, María Del R; González-Méndez, Ricardo; Ayala-Peña, Sylvette; Serrano, Adelfa E

2016-06-01

Plasmodium parasites are exposed to endogenous and exogenous oxidative stress during their complex life cycle. To minimize oxidative damage, the parasites use glutathione (GSH) and thioredoxin (Trx) as primary antioxidants. We previously showed that disruption of the Plasmodium berghei gamma-glutamylcysteine synthetase (pbggcs-ko) or the glutathione reductase (pbgr-ko) genes resulted in a significant reduction of GSH in intraerythrocytic stages, and a defect in growth in the pbggcs-ko parasites. In this report, time course experiments of parasite intraerythrocytic development and morphological studies showed a growth delay during the ring to schizont progression. Morphological analysis shows a significant reduction in size (diameter) of trophozoites and schizonts with increased number of cytoplasmic vacuoles in the pbggcs-ko parasites in comparison to the wild type (WT). Furthermore, the pbggcs-ko mutants exhibited an impaired response to oxidative stress and increased levels of nuclear DNA (nDNA) damage. Reduced GSH levels did not result in mitochondrial DNA (mtDNA) damage or protein carbonylations in neither pbggcs-ko nor pbgr-ko parasites. In addition, the pbggcs-ko mutant parasites showed an increase in mRNA expression of genes involved in oxidative stress detoxification and DNA synthesis, suggesting a potential compensatory mechanism to allow for parasite proliferation. These results reveal that low GSH levels affect parasite development through the impairment of oxidative stress reduction systems and damage to the nDNA. Our studies provide new insights into the role of the GSH antioxidant system in the intraerythrocytic development of Plasmodium parasites, with potential translation into novel pharmacological interventions. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

A Medicago truncatula tobacco retrotransposon insertion mutant collection with defects in nodule development and symbiotic nitrogen fixation.

Science.gov (United States)

Pislariu, Catalina I; Murray, Jeremy D; Wen, JiangQi; Cosson, Viviane; Muni, RajaSekhara Reddy Duvvuru; Wang, Mingyi; Benedito, Vagner A; Andriankaja, Andry; Cheng, Xiaofei; Jerez, Ivone Torres; Mondy, Samuel; Zhang, Shulan; Taylor, Mark E; Tadege, Million; Ratet, Pascal; Mysore, Kirankumar S; Chen, Rujin; Udvardi, Michael K

2012-08-01

A Tnt1-insertion mutant population of Medicago truncatula ecotype R108 was screened for defects in nodulation and symbiotic nitrogen fixation. Primary screening of 9,300 mutant lines yielded 317 lines with putative defects in nodule development and/or nitrogen fixation. Of these, 230 lines were rescreened, and 156 lines were confirmed with defective symbiotic nitrogen fixation. Mutants were sorted into six distinct phenotypic categories: 72 nonnodulating mutants (Nod-), 51 mutants with totally ineffective nodules (Nod+ Fix-), 17 mutants with partially ineffective nodules (Nod+ Fix+/-), 27 mutants defective in nodule emergence, elongation, and nitrogen fixation (Nod+/- Fix-), one mutant with delayed and reduced nodulation but effective in nitrogen fixation (dNod+/- Fix+), and 11 supernodulating mutants (Nod++Fix+/-). A total of 2,801 flanking sequence tags were generated from the 156 symbiotic mutant lines. Analysis of flanking sequence tags revealed 14 insertion alleles of the following known symbiotic genes: NODULE INCEPTION (NIN), DOESN'T MAKE INFECTIONS3 (DMI3/CCaMK), ERF REQUIRED FOR NODULATION, and SUPERNUMERARY NODULES (SUNN). In parallel, a polymerase chain reaction-based strategy was used to identify Tnt1 insertions in known symbiotic genes, which revealed 25 additional insertion alleles in the following genes: DMI1, DMI2, DMI3, NIN, NODULATION SIGNALING PATHWAY1 (NSP1), NSP2, SUNN, and SICKLE. Thirty-nine Nod- lines were also screened for arbuscular mycorrhizal symbiosis phenotypes, and 30 mutants exhibited defects in arbuscular mycorrhizal symbiosis. Morphological and developmental features of several new symbiotic mutants are reported. The collection of mutants described here is a source of novel alleles of known symbiotic genes and a resource for cloning novel symbiotic genes via Tnt1 tagging.

Mutations That Alter the Bacterial Cell Envelope Increase Lipid Production

Energy Technology Data Exchange (ETDEWEB)

Lemmer, Kimberly C.; Zhang, Weiping; Langer, Samantha J.; Dohnalkova, Alice; Hu, Dehong; Lemke, Rachelle A.; Piotrowski, Jeff S.; Orr, Galya; Noguera, Daniel R.; Donohue, Timothy J.

2017-05-23

Lipids from microbes offer a promising source of renewable alternatives to petroleum-derived compounds. In particular, oleaginous microbes are of interest because they accumulate a large fraction of their biomass as lipids. In this study, we analyzed genetic changes that alter lipid accumulation inRhodobacter sphaeroides. By screening anR. sphaeroidesTn5mutant library for insertions that increased fatty acid content, we identified 10 high-lipid (HL) mutants for further characterization. These HL mutants exhibited increased sensitivity to drugs that target the bacterial cell envelope and changes in shape, and some had the ability to secrete lipids, with two HL mutants accumulating ~60% of their total lipids extracellularly. When one of the highest-lipid-secreting strains was grown in a fed-batch bioreactor, its lipid content was comparable to that of oleaginous microbes, with the majority of the lipids secreted into the medium. Based on the properties of these HL mutants, we conclude that alterations of the cell envelope are a previously unreported approach to increase microbial lipid production. We also propose that this approach may be combined with knowledge about biosynthetic pathways, in this or other microbes, to increase production of lipids and other chemicals.

IMPORTANCEThis paper reports on experiments to understand how to increase microbial lipid production. Microbial lipids are often cited as one renewable replacement for petroleum-based fuels and chemicals, but strategies to increase the yield of these compounds are needed to achieve this goal. While lipid biosynthesis is often well understood, increasing yields of these compounds to industrially relevant levels is a challenge, especially since genetic, synthetic biology, or engineering approaches are not feasible in many microbes. We show that altering the bacterial cell envelope can be used to increase

[Biofilm Formation by the Nonflagellated flhB1 Mutant of Azospirillum brasilense Sp245].

Science.gov (United States)

Shelud'ko, A V; Filip'echeva, Yu A; Shumiliva, E M; Khlebtsov, B N; Burov, A M; Petrova, L P; Katsy, E I

2015-01-01

Azospirillum brasilense Sp245 with mixed flagellation are able to form biofilms on various surfaces. A nonflagellated mutant of this strain with inactivated chromosomal copy of the flhB gene (flhB1) was shown to exhibit specific traits at the later stages of biofilm formation on a hydrophilic (glass) surface. Mature biofilms of the flhB1::Omegon-Km mutant Sp245.1063 were considerably thinner than those of the parent strain Sp245. The biofilms of the mutant were more susceptible to the forces of hydrodynamic shear. A. brasilense Sp245 cells in biofilms were not found to possess lateral flagella. Cells with polar flagella were, however, revealed by atomic force microscopy of mature native biofilms of strain Sp245. Preservation of a polar flagellum (probably nonmotile) on the cells of A. brasilense Sp245 may enhance the biofilm stability.

Photoproduct formation and repair capacity in a mutant of Bacillus cereus 569 producing UV-sensitive spores

International Nuclear Information System (INIS)

Weinberger, S.; Evenchik, Z.; Hertman, I.; Bar-Ilan Univ., Ramat-Gan

1982-01-01

A mutant of Bacillus cereus 569 UV sensitive in both vegetative and sporal stages was isolated by N-methyl-N'-nitro-N-nitrosoguanidine (NTG) mutagenesis followed by selection on mitomycin C. The UV-sensitive mutant designated as B. cereus 2422 exhibited normal content of dipicolinic acid (DPA) and resistance to X-rays and ethyl methanesulphonate. The photoproduct type and amount, induced by a given UV dose, was similar in either cells or spores of both the mutant 2422 and the wild-type ancestor. The mutant 2422 excised cyclobutane thymine dimers only to a limited extent (20%) as compared with 80% removal in the wild type. Removal of a spore-specific photoproduct (TDHT) during germination proceeded to a similar extent in B. cereus 2422 and the wild-type parent. However, under growing conditions, an additional removal of the TDHT was observed only in the wild-type strain. Liquid holding recovery occurred in irradiated wild-type cells, but not in mutant cells. Spontaneous revertants were isolated that regained UV resistance simultaneously in both the vegetative and sporal stage. (orig./AJ)

Promising semi-dwarf mutant in wheat variety K68

Energy Technology Data Exchange (ETDEWEB)

Kumar, D [Banaras Hindu Univ. (India). Dept. of Genetics and Plant Breeding

1977-04-01

A semi-dwarf mutant (HUW-SDf 1) was induced from common wheat Var. K68 through the exposure of /sup 60/Co ..gamma..-rays at 15 kR. This mutant along with other induced mutants and control was assessed for yield components, yield and grain quality (M/sub 4/ generation); internode length reduction pattern and the yielding ability at three levels of nitrogen (M/sub 5/ generation). The mutant was significantly shorter in height and almost equal in tillers per plant and grains per spike to K68. However, it showed marked reduction in spike length and spikelets per spike. On the other hand, it possessed significantly higher (50.04 g) 1000-grain weight against control (41.15 g). The mutant gave 56.0% higher yield than the control. Grain quality studies indicated that the mutant possessed significantly higher (14.15%) total protein than K68. It was equally as good as K68 in lysine content. Pelshenke value (62.5 min) of the mutant indicated medium hard nature of gluten as compared to hard nature (198.0) of the control. The mutant showed 24.0% reduction in total culm length compared to K68. Reduction occurred due to maximum and almost equal reduction in 5th and 4th internodes (ca 34.0%) followed by 3rd, 2nd and 1st. The mutant showed similar yield and yield response to increasing nitrogen levels (80 to 160 kg per ha.) as for current commercial semi-dwarf varieties.

Collection of rice mutants and application studies of their agronomic characters

International Nuclear Information System (INIS)

Sun Shuxiang; Jin Wei; Luo Qian; Sheng Ping; Huang Rongmin

1993-01-01

More than 1600 accessions of rice mutant germplasm have been collected since 1980, and 1142 accessions of mutants have been identified according to their agronomy and pattern characters. A part of mutants were compared with their original cultivars in eight main agronomic characters. The results showed that the agronomic characters of mutants induced by ionizing radiations changed to both positive and negative directions compared with their original cultivars. Only 6.3% mutants varied in single agronomic character, and 91.1% mutants varied in two to six agronomic characters. Tenetic analysis and Cellular observations were carried out for two kinds of early mutants. It showed that early mutants 'Yuan Feng Zao' are controlled by two independent and incomplete dominant genes. For the dwarf, the reduction of the number of longitudinal cell layers causes the stem shorter and the increase of the number of horizontal cell layers causes the stem wall thicker. More than 100 preserved accessions of mutants were supplied to breeding units as parents or for genetic studies. Sixteen cultivars (lines) were bred from the parents which played an important role in raising the output of rice production

The Arabidopsis mutant iop1 exhibits induced over-expression of the plant defensin gene PDF1.2 and enhanced pathogen resistance

NARCIS (Netherlands)

Penninckx, I.A.M.A.; Eggermont, K.; Schenk, P.M.; Ackerveken, van den G.; Cammue, B.P.A.; Thomma, B.P.H.J.

2003-01-01

Jasmonate and ethylene are concomitantly involved in the induction of the Arabidopsis plant defensin gene PDF1.2. To define genes in the signal transduction pathway leading to the induction of PDF1.2, we screened for mutants with induced over-expression of a β-glucuronidase reporter, under the

Evaluation of Some Chemical Characteristics of barley Mutants induced by Gamma Irradiation

International Nuclear Information System (INIS)

Abdeldaiem, M.H.; Ali, H.G.M.

2011-01-01

This study aims to evaluate the antioxidant activity of acetonic extract from some barley mutations (P1, P2 and P3 varieties) induced by gamma irradiation as compared with local barley variety (Hordeum vulgare L.) as control. Barley samples were obtained from Plant Breeding Unit, Plant Research Department, Nuclear Research Centre, Atomic Energy Authority, Egypt. The measurements of the antioxidant activity using a radical scavenging capacity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ?-carotene bleaching assay were assessed in the barley acetonic extract. Furthermore, amino acids composition of barley mutant samples was determined. The results indicated that the acetonic extract of barley varieties under investigation possess marked antioxidant and anti radical capacities. The data showed that the acetonic extract of barley mutant P1 possessed the higher antioxidant activity as compared with the antioxidant activities of acetonic extract from control and other barley mutant samples. Meanwhile, the flour of barley mutations under investigation contained trace elements of iron, copper and manganese. GC and mass analyses were used to identify the active compound of extract of control and mutant barley samples. The results illustrated that the main components of the control sample of barely extract was pentane, 3 methyl (47.73%) while gamma irradiation caused noticeable change in the relative percentage of some components of acetonic extract from barley mutant samples. Moreover, the results presented that changes were disappeared, and some compounds of the acetonic extract from mutant barley samples were appeared. Furthermore, the results exhibited that barley flour supplemented with wheat flour at 30% level produced acceptable cookies. Accordingly, the phenolic constituents of barley acetonic extract induced by gamma irradiation, especially samples of P1 mutant, may have a future role as ingredients in the development of functional foods.

SAT2 Foot-and-Mouth Disease Virus Structurally Modified for Increased Thermostability.

Science.gov (United States)

Scott, Katherine A; Kotecha, Abhay; Seago, Julian; Ren, Jingshan; Fry, Elizabeth E; Stuart, David I; Charleston, Bryan; Maree, Francois F

2017-05-15

Foot-and-mouth disease virus (FMDV), particularly strains of the O and SAT serotypes, is notoriously unstable. Consequently, vaccines derived from heat-labile SAT viruses have been linked to the induction of immunity with a poor duration and hence require more frequent vaccinations to ensure protection. In silico calculations predicted residue substitutions that would increase interactions at the interpentamer interface, supporting increased stability. We assessed the stability of the 18 recombinant mutant viruses in regard to their growth kinetics, antigenicity, plaque morphology, genetic stability, and temperature, ionic, and pH stability by using Thermofluor and inactivation assays in order to evaluate potential SAT2 vaccine candidates with improved stability. The most stable mutant for temperature and pH stability was the S2093Y single mutant, while other promising mutants were the E3198A, L2094V, and S2093H single mutants and the F2062Y-H2087M-H3143V triple mutant. Although the S2093Y mutant had the greatest stability, it exhibited smaller plaques, a reduced growth rate, a change in monoclonal antibody footprint, and poor genetic stability properties compared to those of the wild-type virus. However, these factors affecting production can be overcome. The addition of 1 M NaCl was found to further increase the stability of the SAT2 panel of viruses. The S2093Y and S2093H mutants were selected for future use in stabilizing SAT2 vaccines. IMPORTANCE Foot-and-mouth disease virus (FMDV) causes a highly contagious acute vesicular disease in cloven-hoofed livestock and wildlife. The control of the disease by vaccination is essential, especially at livestock-wildlife interfaces. The instability of some serotypes, such as SAT2, affects the quality of vaccines and therefore the duration of immunity. We have shown that we can improve the stability of SAT2 viruses by mutating residues at the capsid interface through predictive modeling. This is an important finding for

Telomerase-Deficient Mice Exhibit Bone Loss Owing to Defects in Osteoblasts and Increased Osteoclastogenesis by Inflammatory Microenvironment

DEFF Research Database (Denmark)

Saeed, H.; Abdallah, B. M.; Ditzel, N.

2011-01-01

Telomere shortening owing to telomerase deficiency leads to accelerated senescence of human skeletal (mesenchymal) stem cells (MSCs) in vitro, whereas overexpression leads to telomere elongation, extended life span, and enhanced bone formation. To study the role of telomere shortening in vivo, we...... studied the phenotype of telomerase-deficient mice (Terc(-/-)).Terc(-/-) mice exhibited accelerated age-related bone loss starting at 3 months of age and during 12 months of follow-up revealed by dual-energy X-ray absorptiometric (DXA) scanning and by micro-computed tomography (mu CT). Bone...... histomorphometry revealed decreased mineralized surface and bone-formation rate as well as increased osteoclast number and size in Terc(-/-) mice. Also, serum total deoxypyridinoline (tDPD) was increased in Terc(-/-) mice. MSCs and osteoprogenitors isolated from Terc(-l-) mice exhibited intrinsic defects...

Enhancement of Echinocandin B Production by a UV- and Microwave-Induced Mutant of Aspergillus nidulans with Precursor- and Biotin-Supplying Strategy.

Science.gov (United States)

Hu, Zhong-Ce; Peng, Li-Yuan; Zheng, Yu-Guo

2016-08-01

Echinocandin B belongs to lipopeptide antifungal antibiotic bearing five types of direct precursor amino acids including proline, ornithine, tyrosine, threonine, and leucine. The objective of this study is to screen over-producing mutant in order to improve echinocandin B production; a stable mutant Aspergillus nidulans ZJB12073, which can use fructose as optimal carbon source instead of expensive mannitol, was selected from thousand isolates after several cycles of UV and microwave irradiation in turn. The results showed that mutant strain ZJB12073 exhibited 1.9-fold improvement in echinocandin B production to 1656.3 ± 40.3 mg/L when compared with the parent strain. Furthermore, the effects of precursor amino acids and some chemicals on echinocandin B biosynthesis in A. nidulans were investigated, respectively. Tyrosine, leucine, and biotin were selected as key factors to optimize the medium employing uniform design method. The results showed that the optimized fermentation medium provided another 63.1 % increase to 2701.6 ± 31.7 mg/L in final echinocandin B concentration compared to that of unoptimized medium.

Evaluation on selected dwarf and semidwarf mutants of upland rice

International Nuclear Information System (INIS)

Riyanti Sumanggono, A.M.

1984-01-01

Seratus malam local upland rice variety was irradiated with gamma-rays at doses of O.1, 0.2, 0.3, 0.4 and 0.5 kGy. Observation of radiation effect was carried out on root and shoot length of M 1 seedlings; plant height, panicle length and number of tiller and seed sterility in M 1 plants. Selection for dwarf and semi-dwarf characteristics were done in M 2 plants, and selected again in M 3 . Observation on radiation effect indicated that 'Seratus Malam' seems to be more resistant than the lowland rice varieties. Increasing doses of radiation caused increasing frequency of chlorophyll mutations as well as chlorophyll mutants. Whereas, selection of dwarf or semi-dwarf in M 2 plants seems that mutant and mutation frequencies decreased as the dose increased. Dose of 0.2 kGy was suitable for selection of dwarf or semi-dwarf plants. Plant height could be influenced by environmental condition. Many of the selected M 2 plants were not really dwarf or semi-dwarf mutants. M 3 evaluation of the selected M 2 plants was really beneficial in the mutant selection. (author)

Histological and Molecular Characterization of Grape Early Ripening Bud Mutant

Directory of Open Access Journals (Sweden)

Da-Long Guo

2016-01-01

Full Text Available An early ripening bud mutant was analyzed based on the histological, SSR, and methylation-sensitive amplified polymorphism (MSAP analysis and a layer-specific approach was used to investigate the differentiation between the bud mutant and its parent. The results showed that the thickness of leaf spongy tissue of mutant (MT is larger than that of wild type (WT and the differences are significant. The mean size of cell layer L2 was increased in the mutant and the difference is significant. The genetic background of bud mutant revealed by SSR analysis is highly uniform to its parent; just the variations from VVS2 SSR marker were detected in MT. The total methylation ratio of MT is lower than that of the corresponding WT. The outside methylation ratio in MT is much less than that in WT; the average inner methylation ratio in MT is larger than that in WT. The early ripening bud mutant has certain proportion demethylation in cell layer L2. All the results suggested that cell layer L2 of the early ripening bud mutant has changed from the WT. This study provided the basis for a better understanding of the characteristic features of the early ripening bud mutant in grape.

Expression of CALR mutants causes mpl-dependent thrombocytosis in zebrafish.

Science.gov (United States)

Lim, K-H; Chang, Y-C; Chiang, Y-H; Lin, H-C; Chang, C-Y; Lin, C-S; Huang, L; Wang, W-T; Gon-Shen Chen, C; Chou, W-C; Kuo, Y-Y

2016-10-07

CALR mutations are identified in about 30% of JAK2/MPL-unmutated myeloproliferative neoplasms (MPNs) including essential thrombocythemia (ET) and primary myelofibrosis. Although the molecular pathogenesis of CALR mutations leading to MPNs has been studied using in vitro cell lines models, how mutant CALR may affect developmental hematopoiesis remains unknown. Here we took advantage of the zebrafish model to examine the effects of mutant CALR on early hematopoiesis and model human CALR-mutated MPNs. We identified three zebrafish genes orthologous to human CALR, referred to as calr, calr3a and calr3b. The expression of CALR-del52 and CALR-ins5 mutants caused an increase in the hematopoietic stem/progenitor cells followed by thrombocytosis without affecting normal angiogenesis. The expression of CALR mutants also perturbed early developmental hematopoiesis in zebrafish. Importantly, morpholino knockdown of mpl but not epor or csf3r could significantly attenuate the effects of mutant CALR. Furthermore, the expression of mutant CALR caused jak-stat signaling activation in zebrafish that could be blocked by JAK inhibitors (ruxolitinib and fedratinib). These findings showed that mutant CALR activates jak-stat signaling through an mpl-dependent mechanism to mediate pathogenic thrombopoiesis in zebrafish, and illustrated that the signaling machinery related to mutant CALR tumorigenesis are conserved between human and zebrafish.

Chinese hamster ovary cell mutants defective in heparan sulfate biosynthesis

International Nuclear Information System (INIS)

Bame, K.J.; Kiser, C.S.; Esko, J.D.

1987-01-01

The authors have isolated Chinese hamster ovary cell mutants defective in proteoglycan synthesis by radiographic screening for cells unable to incorporate 35 SO 4 into acid-precipitable material. Some mutants did not incorporate 35 SO 4 into acid-precipitable material, whereas others incorporated about 3-fold less radioactivity. HPLC anion exchange chromatographic analysis of radiolabelled glycosaminoglycans isolated from these mutants revealed many are defective in heparan sulfate biosynthesis. Mutants 803 and 677 do not synthesize heparan sulfate, although they produce chondroitin sulfate: strain 803 makes chondroitin sulfate normally, whereas 677 overaccumulates chondroitin sulfate by a factor of three. These mutants fall into the same complementation group, suggesting that the mutations are allelic. A second group of heparan sulfate biosynthetic mutants, consisting of cell lines 625, 668 and 679, produce undersulfated heparan sulfate and normal chondroitin sulfate. Treatment of the chains with nitrous acid should determine the position of the sulfate groups along the chain. These mutants may define a complementation group that is defective in the enzymes which modify the heparan sulfate chain. To increase the authors repertoire of heparan sulfate mutants, they are presently developing an in situ enzyme assay to screen colonies replica plated on filter discs for sulfotransferase defects

Nonselective enrichment for yeast adenine mutants by flow cytometry

Science.gov (United States)

Bruschi, C. V.; Chuba, P. J.

1988-01-01

The expression of certain adenine biosynthetic mutations in the yeast Saccharomyces cerevisiae results in a red colony color. This phenomenon has historically provided an ideal genetic marker for the study of mutation, recombination, and aneuploidy in lower eukaryotes by classical genetic analysis. In this paper, it is reported that cells carrying ade1 and/or ade2 mutations exhibit primary fluorescence. Based on this observation, the nonselective enrichment of yeast cultures for viable adenine mutants by using the fluorescence-activated cell sorter has been achieved. The advantages of this approach over conventional genetic analysis of mutation, recombination, and mitotic chromosomal stability include speed and accuracy in acquiring data for large numbers of clones. By using appropriate strains, the cell sorter has been used for the isolation of both forward mutations and chromosomal loss events in S. cerevisiae. The resolving power of this system and its noninvasiveness can easily be extended to more complex organisms, including mammalian cells, in which analogous metabolic mutants are available.

Phanerochaete mutants with enhanced ligninolytic activity

International Nuclear Information System (INIS)

Kakar, S.N.; Perez, A.; Gonzales, J.

1994-01-01

In addition to lignin, the white rot fungus Phanerochaete chrysosporium has the ability to degrade a wide spectrum of recalcitrant organo pollutants in soils and aqueous media. Most of the organic compounds are degraded under ligninolytic conditions with the involvement of the extracellular enzymes, lignin peroxidases, and manganese-dependent peroxidases, which are produced as secondary metabolites triggered by conditions of nutrient starvation (e.g., nitrogen limitation). The fungus and its enzymes can thus provide alternative technologies for bioremediation, bio pulping, bio bleaching, and other industrial applications. The efficiency and effectiveness of the fungus can be enhanced by increasing production and secretion of the important enzymes in large quantities and as primary metabolites under enriched conditions. One way this can be achieved is through isolation of mutants that are deregulated, or are hyper producers or super secretors of key enzymes under enriched conditions. Through UV-light and γ-ray mutagenesis, we have isolated a variety of mutants, some of which produce key enzymes of the ligninolytic system under high-nitrogen growth conditions. One of the mutants, 76UV, produced 272 U of lignin peroxidases enzyme activity/L after 9 d under high nitrogen (although the parent strain does not produce this enzyme under these conditions). The mutant and the parent strains produced up to 54 and 62 U/L, respectively, of the enzyme activity under low nitrogen growth conditions during this period. In some experiments, the mutant showed 281 U/L of enzyme activity under high nitrogen after 17 d

Development mutants of anabaena doliolum defective in repair of UV-damage

International Nuclear Information System (INIS)

Tiwari, D.N.; Singh, C.B.

1980-01-01

Nitrosoguanidine induced 'blue' pigment mutants of the blue-green alga anabaena doliolum were isolated. The blue-mutants on further characterization were grouped into three developmental phenotypes - (i) those forming doli-form blue-spores of heterogenous size i.e., Ad 011, (ii) those forming spheroidal cells in the stationary phase, some of which behave like spores on transfer to fresh medium i.e., Ad 012, and (iii) those showing no sporulation and conditionally producing abnormal cells in the presence of combined nitrogen only i.e., Ad 007. The former two classes of mutants showed the formation of abnormal cells irrespective of the presence or absence of combined nitrogen sources in the medium. The formation of abnormal cells in the filaments of the above mutants were distinguished by their larger size and irregular mode of division leading to true-branch formation. The comparative characterization of these mutant strains with the parental one showed sluggish growth, increased UV-sensitivity, almost unchanged photorepair capacity, a marked change in the pigment composition and relative resistance to nitrosoguanidine. Irregular cell division in both space and time in the mutant strains and their increased sensitivity to ultraviolet irradiation indicate the possible involvement of dark repair system in maintaining the precision of cell cylce in this alga. (orig.) 891 AJ/orig. 892 HIS

Oral treatment with Cu(II)(atsm) increases mutant SOD1 in vivo but protects motor neurons and improves the phenotype of a transgenic mouse model of amyotrophic lateral sclerosis.

Science.gov (United States)

Roberts, Blaine R; Lim, Nastasia K H; McAllum, Erin J; Donnelly, Paul S; Hare, Dominic J; Doble, Philip A; Turner, Bradley J; Price, Katherine A; Lim, Sin Chun; Paterson, Brett M; Hickey, James L; Rhoads, Timothy W; Williams, Jared R; Kanninen, Katja M; Hung, Lin W; Liddell, Jeffrey R; Grubman, Alexandra; Monty, Jean-Francois; Llanos, Roxana M; Kramer, David R; Mercer, Julian F B; Bush, Ashley I; Masters, Colin L; Duce, James A; Li, Qiao-Xin; Beckman, Joseph S; Barnham, Kevin J; White, Anthony R; Crouch, Peter J

2014-06-04

Mutations in the metallo-protein Cu/Zn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) in humans and an expression level-dependent phenotype in transgenic rodents. We show that oral treatment with the therapeutic agent diacetyl-bis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] increased the concentration of mutant SOD1 (SOD1G37R) in ALS model mice, but paradoxically improved locomotor function and survival of the mice. To determine why the mice with increased levels of mutant SOD1 had an improved phenotype, we analyzed tissues by mass spectrometry. These analyses revealed most SOD1 in the spinal cord tissue of the SOD1G37R mice was Cu deficient. Treating with Cu(II)(atsm) decreased the pool of Cu-deficient SOD1 and increased the pool of fully metallated (holo) SOD1. Tracking isotopically enriched (65)Cu(II)(atsm) confirmed the increase in holo-SOD1 involved transfer of Cu from Cu(II)(atsm) to SOD1, suggesting the improved locomotor function and survival of the Cu(II)(atsm)-treated SOD1G37R mice involved, at least in part, the ability of the compound to improve the Cu content of the mutant SOD1. This was supported by improved survival of SOD1G37R mice that expressed the human gene for the Cu uptake protein CTR1. Improving the metal content of mutant SOD1 in vivo with Cu(II)(atsm) did not decrease levels of misfolded SOD1. These outcomes indicate the metal content of SOD1 may be a greater determinant of the toxicity of the protein in mutant SOD1-associated forms of ALS than the mutations themselves. Improving the metal content of SOD1 therefore represents a valid therapeutic strategy for treating ALS caused by SOD1. Copyright © 2014 the authors 0270-6474/14/348021-11$15.00/0.

Enhanced mucosal delivery of antigen with cell wall mutants of lactic acid bacteria.

Science.gov (United States)

Grangette, Corinne; Müller-Alouf, Heide; Hols, Pascal; Goudercourt, Denise; Delcour, Jean; Turneer, Mireille; Mercenier, Annick

2004-05-01

The potential of recombinant lactic acid bacteria (LAB) to deliver heterologous antigens to the immune system and to induce protective immunity has been best demonstrated by using the C subunit of tetanus toxin (TTFC) as a model antigen. Two types of LAB carriers have mainly been used, Lactobacillus plantarum and Lactococcus lactis, which differ substantially in their abilities to resist passage through the stomach and to persist in the mouse gastrointestinal tract. Here we analyzed the effect of a deficiency in alanine racemase, an enzyme that participates in cell wall synthesis, in each of these bacterial carriers. Recombinant wild-type and mutant strains of L. plantarum NCIMB8826 and L. lactis MG1363 producing TTFC intracellularly were constructed and used in mouse immunization experiments. Remarkably, we observed that the two cell wall mutant strains were far more immunogenic than their wild-type counterparts when the intragastric route was used. However, intestinal TTFC-specific immunoglobulin A was induced only after immunization with the recombinant L. plantarum mutant strain. Moreover, the alanine racemase mutant of either LAB strain allowed induction of a much stronger serum TTFC-specific immune response after immunization via the vagina, which is a quite different ecosystem than the gastrointestinal tract. The design and use of these mutants thus resulted in a major improvement in the mucosal delivery of antigens exhibiting vaccine properties.

Genetic Segregation Analysis of a Rapeseed Dwarf Mutant

International Nuclear Information System (INIS)

Xiang, G.; Yu, S.; Zhang, T.; Zhao, J.; Lei, S.; Du, C.

2016-01-01

Dwarf resources in Brassica napus are very important for developing high-yield cultivars through dwarf-type and lodging-resistant breeding. However, few dwarf varieties have been available for this species. Here, we reported a new rapeseed dwarf mutant GRC1157, which exhibits obvious phenotypic variations on dwarf. Six generations (P /sub 1/, P/sub 1/, F/sub 1/, F/sub 1/, B/sub 1/, and B/sub 1/) were produced from a cross between dwarf mutant GRC1157 and an elite tall-type line XR16 to analyze genetic inheritances of plant height (PH), numbers of the 1st valid branch (VBN), main inflorescence length (MIL), pod numbers per main inflorescence (MPN), pod length (PL) and seed numbers per pod (PSN) using the mixed major gene plus polygene inheritance model. The genetic analysis shows different traits were controlled by different inheritance models: PH and PL by two pairs of additive-dominant-epistatic major genes plus additive-dominant-epistatic polygenes, MPN and PSN by two-pair additive-dominant-epistatic major genes plus additive-dominant polygenes, MIL by two-pair additive-dominant-epistatic major genes and VBN by one-pair additive-dominant major genes plus additive-dominant-epistatic polygenes. Furthermore, positive correlations between PH and some other traits were observed, suggesting that some traits may be co-regulated by several linkage or same loci/genes. In addition, high heritability (40.35-93.7 percent) were found for five traits (except VBN) in different segregating generations, indicating these traits were mainly affected by hereditary factors and suitable for early artificial selection. In sum, the dwarf mutant GRC1157 can serve as a valuable resource for rapeseed dwarf breeding and the genetic analysis in this study provided a foundation for further mapping and cloning dwarf genes in mutant GRC1157. (author)

Impaired insulin secretion and glucose intolerance in synaptotagmin-7 null mutant mice

DEFF Research Database (Denmark)

Gustavsson, Natalia; Lao, Ye; Maximov, Anton

2008-01-01

and insulin release. Here, we show that synaptotagmin-7 is required for the maintenance of systemic glucose tolerance and glucose-stimulated insulin secretion. Mutant mice have normal insulin sensitivity, insulin production, islet architecture and ultrastructural organization, and metabolic and calcium...... secretion in pancreatic beta-cells. Of these other synaptotagmins, synaptotagmin-7 is one of the most abundant and is present in pancreatic beta-cells. To determine whether synaptotagmin-7 regulates Ca(2+)-dependent insulin secretion, we analyzed synaptotagmin-7 null mutant mice for glucose tolerance...... responses but exhibit impaired glucose-induced insulin secretion, indicating a calcium-sensing defect during insulin-containing secretory granule exocytosis. Taken together, our findings show that synaptotagmin-7 functions as a positive regulator of insulin secretion and may serve as a calcium sensor...

X-ray-induced mutants resistant to 8-azaguanine

International Nuclear Information System (INIS)

Carver, J.H.; Dewey, W.C.; Hopwood, L.E.

1976-01-01

Asynchronous Chinese hamster ovary cells were irradiated and colony survival in Alpha MEM medium with dialyzed serum was determined with or without 15 μg/ml 8-Azaguanine (AG). Data indicated that a reproducible assay for the system was dependent upon controlling cell density at least two days prior to induction as well as throughout the expression period. Generally, spontaneous and radiation-induced mutant frequencies decreased when cell densities exceeded a critical density of 3-6 x 10 4 cells/cm 2 . Infrequently, the critical density was exceeded by a factor of two with no observed decrease, possibly correlated with a longer cell doubling time. Drug depletion artifacts can occur because of drug degradation, or because wild-type cells utilize the drug or produce conditions which reduce uptake of the drug. Thus, as the effective drug concentration is lowered, the observed mutant frequency increases because a spectrum of mutants resistant to only low concentrations can now survive. In fact, refeeding with AG at intervals during the incubation period lowered spontaneous and radiation-induced frequencies approx. 5-fold. Therefore, to standardize conditions, cells were trypsinized at the end of the expression time and replated at a constant cell number for mutant selection by AG. Over two generations of growth during the expression period were required for optimal manifestation of induced mutants, and when densities were kept below 4 x 10 4 cells/cm 2 at all times, observed mutant frequencies did not change significantly over a period between 80 and 140 h post-induction (over 4 generations for irradiated cells and over 6 generations for controls). Previous reports of observed mutant frequencies decreasing beyond three generations may be due to cell interaction prior to mutant selection

The phenotype of FancB-mutant mouse embryonic stem cells

OpenAIRE

Kim, Tae Moon; Ko, Jun Ho; Choi, Yong Jun; Hu, Lingchuan; Hasty, Paul

2011-01-01

Fanconi anemia (FA) is a rare autosomal recessive disease characterized by bone marrow failure, developmental defects and cancer. There are multiple FA genes that enable the repair of interstrand crosslinks (ICLs) in coordination with a variety of other DNA repair pathways in a way that is poorly understood. Here we present the phenotype of mouse embryonic stem (ES) cells mutated for FancB. We found FancB-mutant cells exhibited reduced cellular proliferation, hypersensitivity to the crosslink...

Gamma ray induced mutants in Colocasia with improved storability

International Nuclear Information System (INIS)

Vasudevan, K.; Jos, J.S.; Padmaja, G.

1989-01-01

Our mutation induction experiments with Colocasia esculenta (taro) were described before. Poor storability of tubers and acridity of tuber flesh in tubers are problems in taro. While screening for induced mutants, variability in shelf-life of tubers was observed. Tubers of the mutant CM 17 did neither spoil nor lose their viability even after storing for 180 days. Yield and results of quality analyses are presented in the Table in comparison with the control variety C 9 (locally known as ''Thamarakkannan''), the check variety Rasmi (well accepted in Kerala) and another mutant CM 1. Besides high yield and long storability, the mutant CM 17 shows a reduction in phenol and sugar, but an increase in dry matter and starch content which were found to be excellent characteristics for making taro chips as the usual browning phenomenon did not occur

The phenotype of FancB-mutant mouse embryonic stem cells

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Moon; Ko, Jun Ho; Choi, Yong Jun; Hu Lingchuan [Department of Molecular Medicine and Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245 (United States); Hasty, Paul, E-mail: hastye@uthscsa.edu [Department of Molecular Medicine and Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 15355 Lambda Drive, San Antonio, TX 78245 (United States)

2011-07-01

Fanconi anemia (FA) is a rare autosomal recessive disease characterized by bone marrow failure, developmental defects and cancer. There are multiple FA genes that enable the repair of interstrand crosslinks (ICLs) in coordination with a variety of other DNA repair pathways in a way that is poorly understood. Here we present the phenotype of mouse embryonic stem (ES) cells mutated for FancB. We found FancB-mutant cells exhibited reduced cellular proliferation, hypersensitivity to the crosslinking agent mitomycin C (MMC), increased spontaneous and MMC-induced chromosomal abnormalities, reduced spontaneous sister chromatid exchanges (SCEs), reduced gene targeting, reduced MMC-induced Rad51 foci and absent MMC-induced FancD2 foci. Since FancB is on the X chromosome and since ES cells are typically XY, FancB is an excellent target for an epistatic analysis to elucidate FA's role in ICL repair.

Gamma-radiation Mutagenesis in Genetically Unstable Barley Mutants. Pt. 2. Comparison of Various Mutants

International Nuclear Information System (INIS)

Balchiuniene, L.

1995-01-01

Spontaneous and gamma-induced mutability was compared in two groups of genetically unstable barley ear structure mutants - tweaky spike (tw) and branched ear (be). Instability in different loci causes different levels of spontaneous and gamma-induced mutability. A high spontaneous level of chlorophyll mutations is peculiar to be-ust mutants. It is suggested that the high level of induced chlorophyll mutations in allelic tw mutants is a result of better surviving of chlorophyll mutation carriers in the genotypical-physiological environment created by mutant tw alleles. (author). 6 refs., 2 tabs

Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation.

Science.gov (United States)

Batista, Marcelo Bueno; Wassem, Roseli; Pedrosa, Fábio de Oliveira; de Souza, Emanuel Maltempi; Dixon, Ray; Monteiro, Rose Adele

2015-05-07

Orthologous proteins of the Crp/Fnr family have been previously implicated in controlling expression and/or activity of the NifA transcriptional activator in some diazotrophs. This study aimed to address the role of three Fnr-like proteins from H. seropedicae SmR1 in controlling NifA activity and consequent NifA-mediated transcription activation. The activity of NifA-dependent transcriptional fusions (nifA::lacZ and nifB::lacZ) was analysed in a series of H. seropedicae fnr deletion mutant backgrounds. We found that combined deletions in both the fnr1 and fnr3 genes lead to higher expression of both the nifA and nifB genes and also an increased level of nifH transcripts. Expression profiles of nifB under different oxygen concentrations, together with oxygen consumption measurements suggest that the triple fnr mutant has higher respiratory activity when compared to the wild type, which we believe to be responsible for greater stability of the oxygen sensitive NifA protein. This conclusion was further substantiated by measuring the levels of NifA protein and its activity in fnr deletion strains in comparison with the wild-type. Fnr proteins are indirectly involved in controlling the activity of NifA in H. seropedicae, probably as a consequence of their influence on respiratory activity in relation to oxygen availability. Additionally we can suggest that there is some redundancy in the physiological function of the three Fnr paralogs in this organism, since altered respiration and effects on NifA activity are only observed in deletion strains lacking both fnr1 and fnr3.

Primary study on lesion mimic mutants of rice (oryza sativa L.)

International Nuclear Information System (INIS)

Hao Zhongna; Zhang Hongzhi; Tao Rongixang

2007-01-01

Nineteen lesion mimic mutants (xsl1-19) of japonica rice Xiushui11 were obtained by γ-rays irradiation treatment. All mutants belonged to whole life lesion mimic. Lesion mimic of mutants didn't largen after tillering stage, leaves didn't wither, and no effect on the plants exsert spikes and seed. When the highest temperature in day exceeded 32 degree C in seedling stage, lesion mimic of all mutant expect xsl19 disappeared. Under 32 degree C, lesion mimic would appear gradually, and symptoms weren't inhibited by high temperature after 5 leaf stage. The plant heights of all lesion mimic mutants were 47.56-63.54 cm in the tillering stage, and that of CK was 83.75 cm; but the dwarf phenomenon of mutants only appeared before tillering stage, and didn't affect plant heights finally; the heading dates of mutants were the same to the CK, the ear length of all mutants were 9.43-15.19 cm, and that of CK was 16.41 cm; the total grain quantity per spike of all mutants were 88.17-165.33, and those of xsl19 and CK were 49.50 and 76.17. The results showed all lesion mimic mutants except xsl19 had short spikes and total grain quantity per spike increasing. All lesion mimic mutants were susceptible to Magnaporthe grisea, and they had no relationship with resistance. (authors)

Promising mutant variety of rice evolved through gamma irradiation

International Nuclear Information System (INIS)

Prasad, S.C.; Sinha, S.K.

1980-01-01

Rice occupies a major share in crop production in the Chotanagpur plateau of Bihar State. Uplands are roughly 40% in area where traditional low yielding rice, known as ''gora'' is cultivated as directly sown crop. Despite introduction of high yielding rice varieties, gora group of rices continue to prevail. It is therefore desired to increase the productivity level of the gora rice by mutation breeding. One such mutant known as ''gora mutant'' was obtained through gamma irradiation (10 kR) of variety Brown gora. The maturity of both parent and mutant remaining constant (ie. 100 days), there is some improvement in other characteristics like plant height, tillering capacity and kernel character. The parent being tall, shy in tillering and red bold kernel, the mutant has dwarfish characteristics, profuse tillering habit and white kernel with fine grains. The yielding capacity of mutant derivative is 30-40% higher than the parent Brown gora. This variety is in pre-release stage, and the farmers have taken great liking for it. (author)

Altered regulation of lipid biosynthesis in a mutant of Arabidopsis deficient in chloroplast glycerol-3-phosphate acyltransferase activity

International Nuclear Information System (INIS)

Kunst, L.; Browse, J.; Somerville, C.

1988-01-01

The leaf membrane lipids of many plant species, including Arabidopsis thaliana (L.) Heynh., are synthesized by two complementary pathways that are associated with the chloroplast and the endoplasmic reticulum. By screening directly for alterations in lipid acyl-group composition, the authors have identified several mutants of Arabidopsis that lack the plastid pathway because of a deficiency in activity of the first enzyme in the plastid pathway of glycerolipid synthesis, acyl-ACP:sn-glycerol-3-phosphate acyltransferase. The lesion results in an increased synthesis of lipids by the cytoplasmic pathway that largely compensates for the loss of the plastid pathway and provides nearly normal amounts of all the lipids required for chloroplast biogenesis. However, the fatty acid composition of the leaf membrane lipids of the mutants is altered because the acyltransferases associated with the two pathways normally exhibit different substrate specificities. The remarkable flexibility of the system provides an insight into the nature of the regulatory mechanisms that allocate lipids for membrane biogenesis

Promising rice mutants

International Nuclear Information System (INIS)

Hakim, L.; Azam, M.A.; Miah, A.J.; Mansur, M.A.; Akanda, H.R.

1988-01-01

Two induced mutants namely, Mut NS 1 (tall) and Mut NS 5 (semi-dwarf) derived from rice variety Nizersail were evaluated for various agronomic characters at four locations in Bangladesh. Both the mutants matured about three weeks earlier and yielded significantly higher than the parent variety Nizersail. (author). 3 tabs., 9 refs

Characteristics and genetic mapping of a lesion mimic mutant pl(t) in japonica rice variety zhejing 22

International Nuclear Information System (INIS)

Chen Pingping; Zhang Xiaoming; Ye Shenghai; Zhao Ningchun; Lu Yanting; Liu Heqin; Jin Qingsheng; Yang Ling

2010-01-01

A lesion mimic mutant,obtained by radiation mutagenesis on the seeds of a japonica rice variety Zhejing 22, exhibited a lesion mimic phenotype during the whole growth stage under different environments. Genetic analysis indicated that the mutant trait was controlled by a single recessive gene named spl (t). Relying on simple sequence repeat (SSR) and recessive class analysis method to map the spl (t) gene with a F 2 population was constructed by crossing the mutant spl (t) with Zhenshan 97B.spl (t) was mapped in the interval of 0.8cM between RM7195 and RM27929 near centromere region on the short arm of chromosome 12.Blue trypan dye analyses indicated that the lesion mimic trait of the mutant was caused by the programmer cell death. Further study showed that the programmer cell death was caused by H 2 O 2 oxidative burst. By inoculation of bacterial leaf blight and blast strains, the resistances of the mutant were similar to the wild variety Zhejing 22. (authors)

Evaluation of Yield and Chemical Characteristics of some Peanut Mutants Induced by Gamma Irradiation

International Nuclear Information System (INIS)

Abd El-daem, G.A.; Anwar, M.M.

2013-01-01

This study was conducted to evaluate some promising mutants in peanut for yielding ability over three generation (M5, M6 and M7) and to evaluate yield attributes as will as chemical characteristics of these mutants in M7 generation induced by 100 Gy gamma radiation. The obtained results showed that the increase of yield / plot over three generation as a percentage of control was 5% for mutant 7, 10.2 % for mutant 10; 22% for mutant 9 and 22.9% for mutant 8. This increase in yield may be due to increase of one or more of yield attributes for most mutant lines. The significant increase for. No .of pods and seeds/ plant, weight of pods and seeds/ plant and 100- seed weight in M7 as compared to the control. For saturated fatty acid composition, results revealed that total saturated fatty acids ranged from 17.79% for mutant 8 to 21.75 for mutant 2 compared to 24.21% for control. Reduction of total saturated fatty acid was noticed for different mutants compared to that of the original variety. However, for total unsaturated fatty acids, results indicated that total unsaturated fatty acid composition ranged from 77.95% for mutant 9 to 82.09% for mutant 8 compared to 75.49% for control. Higher total unsaturated fatty acids for all mutant lines were obtained than that of the control, however, total saturated (TS)/ total unsaturated (TU) ratio was decreased for all mutants compared to control. The physical and chemical contents of Peanut oils showed that the refractive indices were ranged from 1.4620 to 1.4718 specific gravity were in range of 0.9146 to 0.9177. Acid value was range from 0.54 to 0.89% lodine value was ranged from 94.56 to 101.85. Saponification value was ranged from 185.2 to 190.7 and unsaponifiable matter was ranged from 0.98 to 1.33. The peroxide values ranged from 1.15 to 2.33 meq/kg oil. Also, fortified yoghurt made with replaced mutant peanut oil by 50% as milk fat substitute. Data showed that chemical composition and organolyptic properties had the

UV and gamma-ray sensitivity of meiosis-deficient mutants in Podospora anserina

International Nuclear Information System (INIS)

Simonet, J.M.

1976-01-01

Two mutants, mei1 and mei2, were isolated by screening for deficiencies occurring in the meiotic process. The sensitivity of mei1 and mei2 mutant strains to UV irradiation showed a significant increase as compared with that of the wild-type stock, hwhereas the sensitivity to γ-rays remained unchanged. The double-mutant strains were no more sensitive than each single mutant. The data indicate that both mei1 and mei2 loci are probably involved in the same pathway of excision-repair of UV-induced lesions

From crude glycerol to carotenoids by using a Rhodotorula glutinis mutant.

Science.gov (United States)

Cutzu, Raffaela; Coi, Annalisa; Rosso, Fulvia; Bardi, Laura; Ciani, Maurizio; Budroni, Marilena; Zara, Giacomo; Zara, Severino; Mannazzu, Ilaria

2013-06-01

In this work eighteen red yeasts were screened for carotenoids production on glycerol containing medium. Strain C2.5t1 of Rhodotorula glutinis, that showed the highest productivity, was UV mutagenized. Mutant 400A15, that exhibited a 280 % increase in β-carotene production in respect to the parental strain, was selected. A central composite design was applied to 400A15 to optimize carotenoids and biomass productions. Regression analyses of the quadratic polynomial equations obtained (R(2) = 0.87 and 0.94, for carotenoids and biomass, respectively) suggest that the models are reliable and significant (P < 0.0001) in the prediction of carotenoids and biomass productions on the basis of the concentrations of crude glycerol, yeast extract and peptone. Accordingly, total carotenoids production achieved (14.07 ± 1.45 mg l(-1)) under optimized growth conditions was not statistically different from the maximal predicted (14.64 ± 1.57 mg l(-1)) (P < 0.05), and it was about 100 % higher than that obtained under un-optimized conditions. Therefore mutant 400A15 may represent a biocatalyst of choice for the bioconversion of crude glycerol into value-added metabolites, and a tool for the valorization of this by-product of the biodiesel industry.

A KAS2 cDNA complements the phenotypes of the Arabidopsis fab1 mutant that differs in a single residue bordering the substrate binding pocket

DEFF Research Database (Denmark)

Carlsson, A.S.; LaBrie, S.T.; Kinney, A.J.

2002-01-01

The fab1 mutant of Arabidopsis is partially deficient in activity of ß-ketoacyl-[acyl carrier protein] synthase II (KAS II). This defect results in increased levels of 16 : 0 fatty acid and is associated with damage and death of the mutants at low temperature. Transformation of fab1 plants with a c......DNA from Brassica napus encoding a KAS II enzyme resulted in complementation of both mutant phenotypes. The dual complementation by expression of the single gene proves that low-temperature damage is a consequence of altered membrane unsaturation. The fab1 mutation is a single nucleotide change...... chain to bend. For functional analysis the equivalent Leu207Phe mutation was introduced into the fabB gene encoding the E. coli KAS I enzyme. Compared to wild-type, the Leu207Phe protein showed a 10-fold decrease in binding affinity for the fatty acid substrate, exhibited a modified behavior during size...

Enhanced lipid productivity and photosynthesis efficiency in a Desmodesmus sp. mutant induced by heavy carbon ions.

Science.gov (United States)

Hu, Guangrong; Fan, Yong; Zhang, Lei; Yuan, Cheng; Wang, Jufang; Li, Wenjian; Hu, Qiang; Li, Fuli

2013-01-01

The unicellular green microalga Desmodesmus sp. S1 can produce more than 50% total lipid of cell dry weight under high light and nitrogen-limitation conditions. After irradiation by heavy (12)C(6+) ion beam of 10, 30, 60, 90 or 120 Gy, followed by screening of resulting mutants on 24-well microplates, more than 500 mutants were obtained. One of those, named D90G-19, exhibited lipid productivity of 0.298 g L(-1)⋅d(-1), 20.6% higher than wild type, likely owing to an improved maximum quantum efficiency (Fv/Fm) of photosynthesis under stress. This work demonstrated that heavy-ion irradiation combined with high-throughput screening is an effective means for trait improvement. The resulting mutant D90G-19 may be used for enhanced lipid production.

Increased production of biomass-degrading enzymes by double deletion of creA and creB genes involved in carbon catabolite repression in Aspergillus oryzae.

Science.gov (United States)

Ichinose, Sakurako; Tanaka, Mizuki; Shintani, Takahiro; Gomi, Katsuya

2018-02-01

In a previous study, we reported that a double gene deletion mutant for CreA and CreB, which constitute the regulatory machinery involved in carbon catabolite repression, exhibited improved production of α-amylase compared with the wild-type strain and single creA or creB deletion mutants in Aspergillus oryzae. Because A. oryzae can also produce biomass-degrading enzymes, such as xylolytic and cellulolytic enzymes, we examined the production levels of those enzymes in deletion mutants in this study. Xylanase and β-glucosidase activities in the wild-type were hardly detected in submerged culture containing xylose as the carbon source, whereas those enzyme activities were significantly increased in the single creA deletion (ΔcreA) and double creA and creB deletion (ΔcreAΔcreB) mutants. In particular, the ΔcreAΔcreB mutant exhibited >100-fold higher xylanase and β-glucosidase activities than the wild-type. Moreover, in solid-state culture, the β-glucosidase activity of the double deletion mutant was >7-fold higher than in the wild-type. These results suggested that deletion of both creA and creB genes could also efficiently improve the production levels of biomass-degrading enzymes in A. oryzae. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Fisetin Exerts Antioxidant and Neuroprotective Effects in Multiple Mutant hSOD1 Models of Amyotrophic Lateral Sclerosis by Activating ERK.

Science.gov (United States)

Wang, T H; Wang, S Y; Wang, X D; Jiang, H Q; Yang, Y Q; Wang, Y; Cheng, J L; Zhang, C T; Liang, W W; Feng, H L

2018-05-21

Oxidative stress exhibits a central role in the course of amyotrophic lateral sclerosis (ALS), a progressive neurodegenerative disease commonly found to include a copper/zinc superoxide dismutase (SOD1) gene mutation. Fisetin, a natural antioxidant, has shown benefits in varied neurodegenerative diseases. The possible effect of fisetin in ALS has not been clarified as of yet. We investigated whether fisetin affected mutant hSOD1 ALS models. Three different hSOD1-related mutant models were used: Drosophila expressing mutant hSOD1 G85R , hSOD1 G93A NSC34 cells, and transgenic mice. Fisetin treatment provided neuroprotection as demonstrated by an improved survival rate, attenuated motor impairment, reduced ROS damage and regulated redox homeostasis compared with those in controls. Furthermore, fisetin increased the expression of phosphorylated ERK and upregulated antioxidant factors, which were reversed by MEK/ERK inhibition. Finally, fisetin reduced the levels of both mutant and wild-type hSOD1 in vivo and in vitro, as well as the levels of detergent-insoluble hSOD1 proteins. The results indicate that fisetin protects cells from ROS damage and improves the pathological behaviors caused by oxidative stress in disease models related to SOD1 gene mutations probably by activating ERK, thereby providing a potential treatment for ALS. Copyright © 2018 IBRO. Published by Elsevier Ltd. All rights reserved.

Evaluation of short stature mutants of Basmati-370 for yield and grain quality characteristics

International Nuclear Information System (INIS)

Awan, M.A.; Ahmad, M.; Cheema, A.A.

1982-01-01

Three short stature mutants were induced in an indica rice cultivar by gamma irradiation. The mutants were assessed for their yielding ability and grain quality characteristics. All the mutants out yielded the parent variety, Basmati-370. The increase in yield of the mutants ranged from 19.37% to 29.66%. DM-2 gave the highest yield (3587.96 kg/ha) among the mutants. As regards physical, cooking and eating quality characteristics, there was no significant difference in water absorption, volume expansion ratios and stickiness among the mutants and Basmati-370. However, Basmati-370 was scored best for flavour as this variety had strong aroma as compared to its mutants which were scored for moderately strong aroma. (authors)

Arabidopsis thaliana cdd1 mutant uncouples the constitutive activation of salicylic acid signalling from growth defects.

Science.gov (United States)

Swain, Swadhin; Roy, Shweta; Shah, Jyoti; Van Wees, Saskia; Pieterse, Corné M; Nandi, Ashis K

2011-12-01

Arabidopsis genotypes with a hyperactive salicylic acid-mediated signalling pathway exhibit enhanced disease resistance, which is often coupled with growth and developmental defects, such as dwarfing and spontaneous necrotic lesions on the leaves, resulting in reduced biomass yield. In this article, we report a novel recessive mutant of Arabidopsis, cdd1 (constitutive defence without defect in growth and development1), that exhibits enhanced disease resistance associated with constitutive salicylic acid signalling, but without any observable pleiotropic phenotype. Both NPR1 (NON-EXPRESSOR OF PATHOGENESIS-RELATED GENES1)-dependent and NPR1-independent salicylic acid-regulated defence pathways are hyperactivated in cdd1 mutant plants, conferring enhanced resistance against bacterial pathogens. However, a functional NPR1 allele is required for the cdd1-conferred heightened resistance against the oomycete pathogen Hyaloperonospora arabidopsidis. Salicylic acid accumulates at elevated levels in cdd1 and cdd1 npr1 mutant plants and is necessary for cdd1-mediated PR1 expression and disease resistance phenotypes. In addition, we provide data which indicate that the cdd1 mutation negatively regulates the npr1 mutation-induced hyperactivation of ethylene/jasmonic acid signalling. © 2011 The Authors. Molecular Plant Pathology © 2011 BSPP and Blackwell Publishing Ltd.

physical, chemical, technological and biological properties of some mutant oil seeds induced by gamma radiation

International Nuclear Information System (INIS)

Ali, H.G.M.

2003-01-01

The present study has been undertaken to evaluated sesame, sunflower and safflower seeds induced by gamma rays, as plant breeding unit, plant research department, radioisotope application division, nuclear research center, atomic energy authority Inshas. the obtained results indicate the following : chemical composition of mutant seeds: the radiation mutation caused a significant increase in both oil and ash content total carbohydrates showed a significant decreased in sesame seeds. radiation mutation induced significant increase in oil and protein content of sunflower and safflower seeds. while the total carbohydrate showed a significant decrease. physiochemical properties of oils extracted mutant seeds: the radiation mutation had no real effect on the refractive index and A.V of oils extracted from control and mutant sesame, sunflower and safflower seeds. while it caused a slight increase in red color and P.V. of sesame oil, the thiobarbituric acid (TBA) value of mutant sesame oil was not alter upon radiation mutation, but it induced a slight decrease in TBA of mutant sunflower and safflower oils. the unsaponifiable matter percentage of oils extracted from mutant sesame, sunflower and safflower seeds were slightly increased by radiation mutation .radiation mutation of seeds had no real effect on the total SFA and USFA of sesame oil. however, radiation mutation induced a remarkable changes in fatty acid profiles of sunflower and safflower oil as total SFA decreased, while USFA increased. Uric acid was only detected in oil extracted from mutant sunflower seeds

Functional verification of a porcine myostatin propeptide mutant.

Science.gov (United States)

Ma, Dezun; Jiang, Shengwang; Gao, Pengfei; Qian, Lili; Wang, Qingqing; Cai, Chunbo; Xiao, Gaojun; Yang, Jinzeng; Cui, Wentao

2015-10-01

Myostatin is a member of TGF-β superfamily that acts as a key negative regulator in development and growth of embryonic and postnatal muscles. In this study, the inhibitory activities of recombinant porcine myostatin propeptide and its mutated form (at the cleavage site of metalloproteinases of BMP-1/TLD family) against murine myostatin was evaluated in vivo by intraperitoneal injection into mice. Results showed that both wild type and mutated form of porcine propeptide significantly inhibited myostatin activity in vivo. The average body weight of mice receiving wild type propeptide or its mutated form increased by 12.5 % and 24.14%, respectively, compared to mice injected with PBS, implying that the in vivo efficacy of porcine propeptide mutant is greater than its wild type propeptide. Transgenic mice expressing porcine myostatin propeptide mutant were generated to further verify the results obtained from mice injected with recombinant porcine propeptide mutant. Compared with wild type (non-transgenic) mice, relative weight of gastrocnemius, rectusfemoris, and tibialis anterior increased by 22.14 %, 34.13 %, 25.37%, respectively, in transgenic male mice, and by 19.90 %, 42.47 %, 45.61%, respectively, in transgenic female mice. Our data also demonstrated that the mechanism by which muscle growth enhancement is achieved by these propeptides is due to an increase in fiber sizes, not by an increase in number of fiber cells.

Towards a "Golden Standard" for computing globin stability: Stability and structure sensitivity of myoglobin mutants.

Science.gov (United States)

Kepp, Kasper P

2015-10-01

Fast and accurate computation of protein stability is increasingly important for e.g. protein engineering and protein misfolding diseases, but no consensus methods exist for important proteins such as globins, and performance may depend on the type of structural input given. This paper reports benchmarking of six protein stability calculators (POPMUSIC 2.1, I-Mutant 2.0, I-Mutant 3.0, CUPSAT, SDM, and mCSM) against 134 experimental stability changes for mutations of sperm-whale myoglobin. Six different high-resolution structures were used to test structure sensitivity that may impair protein calculations. The trend accuracy of the methods decreased as I-Mutant 2.0 (R=0.64-0.65), SDM (R=0.57-0.60), POPMUSIC2.1 (R=0.54-0.57), I-Mutant 3.0 (R=0.53-0.55), mCSM (R=0.35-0.47), and CUPSAT (R=0.25-0.48). The mean signed errors increased as SDMMean absolute errors increased as I-Mutant 2.0Mutant 3.0increased as I-Mutant 3.0 (0.05)Mutant 2.0 (0.09)Mutant 2.0 is proficient for this purpose, as further validated against a data set of related cytochrome c like proteins. The results also emphasize the importance of high-quality crystal structures and reveal structure-dependent effects even in the near-atomic resolution limit. Copyright © 2015 Elsevier B.V. All rights reserved.

Increased dopaminergic signaling impairs aversive olfactory memory retention in Drosophila.

Science.gov (United States)

Zhang, Shixing; Yin, Yan; Lu, Huimin; Guo, Aike

2008-05-23

Dopamine is necessary for the aversive olfactory associative memory formation in Drosophila, but its effect on other stages of memory is not known. Herein, we studied the effect of enhanced dopaminergic signaling on aversive olfactory memory retention in flies. We used l-3,4-dihydroxyphenylalanine (l-DOPA) to elevate dopamine levels: l-DOPA-treated flies exhibited a normal learning performance, but a decrease in 1-h memory. Dopamine transporter (DAT) mutant flies or flies treated with the DAT inhibitor desipramine exhibited poor memory retention. Flies subjected to heat stress after training exhibited a decrease in memory. Memory was restored by blocking dopaminergic neuronal output during heat stress, suggesting that dopamine is involved in heat stress-induced memory impairment in flies. Taken together, our findings suggest that increased dopaminergic signaling impairs aversive olfactory memory retention in flies.

Development of high yielding mutants in lentil

International Nuclear Information System (INIS)

Rajput, M.A.; Sarwar, G.; Siddiqui, K.A.

2001-01-01

Full text: Lentil (Lens culinaris Medik.) locally known as Masoor, is the second most important rabi pulse crop, after chickpea, in Pakistan. It is cultivated on an area of over 63,400 ha, which constitutes about 4.83% of the total area under pulses. The annual production of the crop is 28,200 tones with an average yield of 445 kg/ha. Yield at the national level is very low, about one-half of the world's yield, which is mainly due to non-availability of high yield potential genotypes. Keeping in view the importance of mutants in developing a large number of new varieties, an induced mutations programme was initiated at AEARC, Tandojam during 1987-88, to develop high yielding varieties in lentil. For this, seeds of two lentil varieties, 'Masoor-85' and 'ICARDA-8' had been irradiated with gamma-rays ranging from 100-600 Gy in NIAB, Faisalabad during 1990. Selections were made in M2 on the basis of earliness, plant height, branches/plant and 100 grain weight. After confirming these mutants in M3 they were promoted in station yield trials and studied continuously for three consecutive years (1993- 1995). Overall results revealed that these mutants have consistent improvement of earliness in flowering and maturity. Plant height also increased in all mutant lines except AEL 23/40/91 where reduction in this attribute was observed as compared to parent variety. Mutant lines AEL 49/20/91 and AEL 13/30/91 showed improvement in 100 grain weight. The improvement of some agronomic characters enhanced the yield of mutant lines in comparison to parent varieties (Masoor-85 and ICARDA-8). The diversity in yield over the respective parents was computed from 6.94 to 60.12%. From these encouraging results it is hoped that mutant lines like AEL 12/30/91 and AEL 49/20/91 may serve as potential lentil genotypes in future. (author)

Evaluation of Chemical Changes in Some Soybean Mutants Induced by Gamma Irradiation

International Nuclear Information System (INIS)

Abd-Elkalik, K.; Mekkawy, S.H.; El-Demerdash, H.M.

2010-01-01

The Egyptian soybean cultivar Giza-22 was used to induce genetic variability by using gamma rays at dose levels of 100, 150 and 200 Gy. Sixteen mutants (including parental cultivar) were evaluated in M3 generation for their agronomic traits and chemical analysis was done in seeds of M3 generation. Four mutants A21 (150 Gy), A22, A23 and A24 (200 Gy) showed superiority in their agronomic traits compared with parental cultivar. The results of chemical analysis of seeds of M3 generation showed that, oil and energy contents were unaffected by irradiation treatments while protein contents were significantly increased at doses 150 and 200 Gy. Phenolic and tannin contents in seeds of M3 generation showed no significant changes in their percentages due to irradiation treatments. Gamma irradiation significantly increased in linoleic acid content in most of the mutants compared with the control (Giza-22), whereas, there were decreases in linolenic acid content. Investigation of amino acid composition of mutants of M3 generation revealed significant increases in the essential amino acids in most mutants induced by gamma irradiation at 150 and 200 Gy. It could be suggested that the use of gamma irradiation can induce an improvement of the oil and protein composition in soybean

Proteostasis and ageing: insights from long-lived mutant mice.

Science.gov (United States)

Sands, William A; Page, Melissa M; Selman, Colin

2017-10-15

The global increase in life expectancy is creating significant medical, social and economic challenges to current and future generations. Consequently, there is a need to identify the fundamental mechanisms underlying the ageing process. This knowledge should help develop realistic interventions capable of combatting age-related disease, and thus improving late-life health and vitality. While several mechanisms have been proposed as conserved lifespan determinants, the loss of proteostasis - where proteostasis is defined here as the maintenance of the proteome - appears highly relevant to both ageing and disease. Several studies have shown that multiple proteostatic mechanisms, including the endoplasmic reticulum (ER)-induced unfolded protein response (UPR), the ubiquitin-proteasome system (UPS) and autophagy, appear indispensable for longevity in many long-lived invertebrate mutants. Similarly, interspecific comparisons suggest that proteostasis may be an important lifespan determinant in vertebrates. Over the last 20 years a number of long-lived mouse mutants have been described, many of which carry single-gene mutations within the growth-hormone, insulin/IGF-1 or mTOR signalling pathways. However, we still do not know how these mutations act mechanistically to increase lifespan and healthspan, and accordingly whether mechanistic commonality occurs between different mutants. Recent evidence supports the premise that the successful maintenance of the proteome during ageing may be linked to the increased lifespan and healthspan of long-lived mouse mutants. © 2017 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.

Human stefin B normal and patho-physiological role: molecular and cellular aspects of amyloid-type aggregation of certain EPM1 mutants.

Directory of Open Access Journals (Sweden)

Mira ePolajnar

2012-08-01

Full Text Available Epilepsies are characterised by abnormal electrophysiological activity of the brain. Among various types of inherited epilepsies different epilepsy syndromes, among them progressive myoclonus epilepsies with features of ataxia and neurodegeneration, are counted. The progressive myoclonus epilepsy of type 1 (EPM1, also known as Unverricht-Lundborg disease presents with features of cerebellar atrophy and increased oxidative stress. It has been found that EPM1 is caused by mutations in human cystatin B gene (human stefin B. We first describe the role of protein aggregation in other neurodegenerative conditions. Protein aggregates appear intraneurally but are also excreted, such as is the case with senile plaques of amyloid- β (Aβ that accumulate in the brain parenchyma and vessel walls. A common characteristic of such diseases is the change of the protein conformation towards β secondary structure that accounts for the strong tendency of such proteins to aggregate and form amyloid fibrils. Second, we describe the patho-physiology of EPM1 and the normal and aberrant roles of stefin B in a mouse model of the disease. Furthermore, we discuss how the increased protein aggregation observed with some of the mutants of human stefin B may relate to the neurodegeneration that occurs in rare EPM1 patients. Our hypothesis (Ceru et al., 2005 states that some of the EPM1 mutants of human stefin B may undergo aggregation in neural cells, thus gaining additional toxic function (apart from loss of normal function. Our in vitro experiments thus far have confirmed that 4 mutants undergo increased aggregation relative to the wild-type protein. It has been shown that the R68X mutant forms amyloid-fibrils very rapidly, even at neutral pH and forms perinuclear inclusions, whereas the G4R mutant exhibits a prolonged lag phase, during which the toxic prefibrillar aggregates accumulate and are scattered more diffusely over the cytoplasm. Initial experiments on the G50E

Effect of Bacillus subtilis mutants on growth performance of piglets fed tryptophan- and valine-deficient diets

DEFF Research Database (Denmark)

Nørgaard, Jan Værum; Canibe, Nuria; Assadi Soumeh, Elham

2016-01-01

The objective was to determine the concentration of l-Trp and l-Val to be substituted by feeding piglets Bacillus subtilis strains developed to overproduce Trp (B. subtilis Trp mutant [BsTrp]) and Val (B. subtilis Val mutant [BsVal]) and by using equations obtained in 3 dose–response studies......-Val per kilogram feed using curvilinear plateau and broken-line equations obtained by modeling the 6 AA levels. Bacillus subtilis Val mutant increased animal performance corresponding to 0.88 and 0.39 g l-Leu and 0.17 and 0.44 g l-Val per kilogram feed for 10x and 100x doses, respectively. Bacillus...... subtilis Trp mutant was equivalent to 0.02 and 0.11 g l-Trp/kg feed for 10x and 100x doses, respectively. Bacillus subtilis Val mutant (10x dose) increased (P Bacillus subtilis Trp mutant tended (P = 0.06) to increase Trp plasma concentrations...

The Swedish mutant barley collection

Energy Technology Data Exchange (ETDEWEB)

NONE

1989-07-01

Full text: The Swedish mutation research programme in barley began about 50 years ago and has mainly been carried out at Svaloev in co-operation with the institute of Genetics at the University of Lund. The collection has been produced from different Swedish high-yielding spring barley varieties, using the following mutagens: X-rays, neutrons, several organic chemical compounds such as ethyleneimine, several sulfonate derivatives and the inorganic chemical mutagen sodium azide. Nearly 10,000 barley mutants are stored in the Nordic Gene Bank and documented in databases developed by Udda Lundquist, Svaloev AB. The collection consists of the following nine categories with 94 different types of mutants: 1. Mutants with changes in the spike and spikelets; 2. Changes in culm length and culm composition; 3. Changes in growth types; 4. Physiological mutants; 5. Changes in awns; 6. Changes in seed size and shape; 7. Changes in leaf blades; 8. Changes in anthocyanin and colour; 9. Resistance to barley powdery mildew. Barley is one of the most thoroughly investigated crops in terms of induction of mutations and mutation genetics. So far, about half of the mutants stored at the Nordic Gene Bank, have been analysed genetically; They constitute, however, only a minority of the 94 different mutant types. The genetic analyses have given valuable insights into the mutation process but also into the genetic architecture of various characters. A number of mutants of two-row barley have been registered and commercially released. One of the earliest released, Mari, an early maturing, daylength neutral, straw stiff mutant, is still grown in Iceland. The Swedish mutation material has been used in Sweden, but also in other countries, such as Denmark, Germany, and USA, for various studies providing a better understanding of the barley genome. The collection will be immensely valuable for future molecular genetical analyses of clone mutant genes. (author)

The Swedish mutant barley collection

International Nuclear Information System (INIS)

1989-01-01

Full text: The Swedish mutation research programme in barley began about 50 years ago and has mainly been carried out at Svaloev in co-operation with the institute of Genetics at the University of Lund. The collection has been produced from different Swedish high-yielding spring barley varieties, using the following mutagens: X-rays, neutrons, several organic chemical compounds such as ethyleneimine, several sulfonate derivatives and the inorganic chemical mutagen sodium azide. Nearly 10,000 barley mutants are stored in the Nordic Gene Bank and documented in databases developed by Udda Lundquist, Svaloev AB. The collection consists of the following nine categories with 94 different types of mutants: 1. Mutants with changes in the spike and spikelets; 2. Changes in culm length and culm composition; 3. Changes in growth types; 4. Physiological mutants; 5. Changes in awns; 6. Changes in seed size and shape; 7. Changes in leaf blades; 8. Changes in anthocyanin and colour; 9. Resistance to barley powdery mildew. Barley is one of the most thoroughly investigated crops in terms of induction of mutations and mutation genetics. So far, about half of the mutants stored at the Nordic Gene Bank, have been analysed genetically; They constitute, however, only a minority of the 94 different mutant types. The genetic analyses have given valuable insights into the mutation process but also into the genetic architecture of various characters. A number of mutants of two-row barley have been registered and commercially released. One of the earliest released, Mari, an early maturing, daylength neutral, straw stiff mutant, is still grown in Iceland. The Swedish mutation material has been used in Sweden, but also in other countries, such as Denmark, Germany, and USA, for various studies providing a better understanding of the barley genome. The collection will be immensely valuable for future molecular genetical analyses of clone mutant genes. (author)

Studies on an X-ray induced crinkled leaf mutant of Trichosanthes anguina L

International Nuclear Information System (INIS)

Datta, Subodh Kumar

1986-01-01

Crinkled leaf mutant isolated in the second generation after treatment with X-ray bred true in subsequent generation. The mutant was a late flowering type with increased percentage of PMC's with chromosomal abnormality and pollen grain sterility. TLC study on phenolic compounds in leaves showed that both the mother line and the mutant had equal number of spots but they differed from each other with respect to four spots. Spot Nos. 2 and 4 of the mother line were absent in the mutant but the latter had two new spots (spot Nos. 11 and 12). The mutant and the mother line also differed from each other in pollen grain morohology. (author)

Identification, cloning and characterization of sis7 and sis10 sugar-insensitive mutants of Arabidopsis

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Biddle Kelly D

2008-10-01

Full Text Available Abstract Background The levels of soluble sugars, such as glucose and sucrose, help regulate many plant metabolic, physiological and developmental processes. Genetic screens are helping identify some of the loci involved in plant sugar response and reveal extensive cross-talk between sugar and phytohormone response pathways. Results A forward genetic screen was performed to identify mutants with increased resistance to the inhibitory effects of high levels of exogenous sugars on early Arabidopsis seedling development. The positional cloning and characterization of two of these sugar insensitive (sis mutants, both of which are also involved in abscisic acid (ABA biosynthesis or response, are reported. Plants carrying mutations in SIS7/NCED3/STO1 or SIS10/ABI3 are resistant to the inhibitory effects of high levels of exogenous Glc and Suc. Quantitative RT-PCR analyses indicate transcriptional upregulation of ABA biosynthesis genes by high concentrations of Glc in wild-type germinating seeds. Gene expression profiling revealed that a significant number of genes that are expressed at lower levels in germinating sis7-1/nced3-4/sto1-4 seeds than in wild-type seeds are implicated in auxin biosynthesis or transport, suggesting cross-talk between ABA and auxin response pathways. The degree of sugar insensitivity of different sis10/abi3 mutant seedlings shows a strong positive correlation with their level of ABA insensitivity during seed germination. Conclusion Mutations in the SIS7/NCED3/STO1 gene, which is primarily required for ABA biosynthesis under drought conditions, confer a sugar-insensitive phenotype, indicating that a constitutive role in ABA biosynthesis is not necessary to confer sugar insensitivity. Findings presented here clearly demonstrate that mutations in ABI3 can confer a sugar-insensitive phenotype and help explain previous, mixed reports on this topic by showing that ABA and sugar insensitivity exhibit a strong positive correlation in

A Caulobacter MreB mutant with irregular cell shape exhibits compensatory widening to maintain a preferred surface area to volume ratio

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Harris, Leigh K.; Dye, Natalie A.; Theriot, Julie A.

2014-01-01

Summary Rod-shaped bacteria typically elongate at a uniform width. To investigate the genetic and physiological determinants involved in this process, we studied a mutation in the morphogenetic protein MreB in Caulobacter crescentus that gives rise to cells with a variable-width phenotype, where cells have regions that are both thinner and wider than wild-type. During growth, individual cells develop a balance of wide and thin regions, and mutant MreB dynamically localizes to poles and thin regions. Surprisingly, the surface area to volume ratio of these irregularly-shaped cells is, on average, very similar to wild-type. We propose that, while mutant MreB localizes to thin regions and promotes rod-like growth there, wide regions develop as a compensatory mechanism, allowing cells to maintain a wild-type-like surface area to volume ratio. To support this model, we have shown that cell widening is abrogated in growth conditions that promote higher surface area to volume ratios, and we have observed individual cells with high ratios return to wild-type levels over several hours by developing wide regions, suggesting that compensation can take place at the level of individual cells. PMID:25266768

Intrinsic properties of lumbar motor neurones in the adult G127insTGGG superoxide dismutase-1 mutant mouse in vivo: evidence for increased persistent inward currents

DEFF Research Database (Denmark)

Meehan, Claire Francesca; Moldovan, Mihai; Marklund, Stefan L.

2010-01-01

Aim: Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease characterized by a preferential loss of motoneurones. Previous publications using in vitro neonatal preparations suggest an increased excitability of motoneurones in various superoxide dismutase-1 (SOD1) mutant mice...... of an increased PIC and less spike frequency adaptation which may contribute to excitotoxity of these neurones as the disease progresses....

Competitive Interactions Between Incompatible Mutants of the Social Bacterium Myxococcus xanthus DK1622

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Ya Gong

2018-06-01

Full Text Available Due to the high similarity in their requirements for space and food, close bacterial relatives may be each other's strongest competitors. Close bacterial relatives often form visible boundaries to separate their swarming colonies, a phenomenon termed colony-merger incompatibility. While bacterial species are known to have many incompatible strains, it is largely unclear which traits lead to multiple incompatibilities and the interactions between multiple incompatible siblings. To investigate the competitive interactions of closely related incompatible strains, we mutated Myxococcus xanthus DK1622, a predatory bacterium with complex social behavior. From 3392 random transposon mutations, we obtained 11 self-identification (SI deficient mutants that formed unmerged colony boundaries with the ancestral strain. The mutations were at nine loci with unknown functions and formed nine independent SI mutants. Compared with their ancestral strain, most of the SI mutants showed reduced growth, swarming and development abilities, but some remained unchanged from their monocultures. When pairwise mixed with their ancestral strain for co-cultivation, these mutants exhibited improved, reduced or unchanged competitive abilities compared with the ancestral strain. The sporulation efficiencies were affected by the DK1622 partner, ranging from almost complete inhibition to 360% stimulation. The differences in competitive growth between the SI mutants and DK1622 were highly correlated with the differences in their sporulation efficiencies. However, the competitive efficiencies of the mutants in mixture were inconsistent with their growth or sporulation abilities in monocultures. We propose that the colony-merger incompatibility in M. xanthus is associated with multiple independent genetic loci, and the incompatible strains hold competitive interaction abilities, which probably determine the complex relationships between multiple incompatible M. xanthus strains and

Increased RhoA prenylation in the loechrig (loe mutant leads to progressive neurodegeneration.

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Mandy Cook

Full Text Available The Drosophila mutant loechrig (loe shows age-dependent degeneration of the nervous system and is caused by the loss of a neuronal isoform of the AMP-activated protein kinase (AMPK γ-subunit (also known as SNF4Aγ. The trimeric AMPK complex is activated by low energy levels and metabolic insults and regulates multiple important signal pathways that control cell metabolism. A well-known downstream target of AMPK is hydroxyl-methylglutaryl-CoA reductase (HMGR, a key enzyme in isoprenoid synthesis, and we have previously shown that HMGR genetically interacts with loe and affects the severity of the degenerative phenotype. Prenylation of proteins like small G-proteins is an important posttranslational modification providing lipid moieties that allow the association of these proteins with membranes, thereby facilitating their subsequent activation. Rho proteins have been extensively studied in neuronal outgrowth, however, much less is known about their function in neuronal maintenance. Here we show that the loe mutation interferes with isoprenoid synthesis, leading to increased prenylation of the small GTPase Rho1, the fly orthologue of vertebrate RhoA. We also demonstrate that increased prenylation and Rho1 activity causes neurodegeneration and aggravates the behavioral and degenerative phenotypes of loe. Because we cannot detect defects in the development of the central nervous system in loe, this suggests that loe only interferes with the function of the RhoA pathway in maintaining neuronal integrity during adulthood. In addition, our results show that alterations in isoprenoids can result in progressive neurodegeneration, supporting findings in vertebrates that prenylation may play a role in neurodegenerative diseases like Alzheimer's Disease.

Gr and hp-1 tomato mutants unveil unprecedented interactions between arbuscular mycorrhizal symbiosis and fruit ripening.

Science.gov (United States)

Chialva, Matteo; Zouari, Inès; Salvioli, Alessandra; Novero, Mara; Vrebalov, Julia; Giovannoni, James J; Bonfante, Paola

2016-07-01

Systemic responses to an arbuscular mycorrhizal fungus reveal opposite phenological patterns in two tomato ripening mutants depending whether ethylene or light reception is involved. The availability of tomato ripening mutants has revealed many aspects of the genetics behind fleshy fruit ripening, plant hormones and light signal reception. Since previous analyses revealed that arbuscular mycorrhizal symbiosis influences tomato berry ripening, we wanted to test the hypothesis that an interplay might occur between root symbiosis and fruit ripening. With this aim, we screened seven tomato mutants affected in the ripening process for their responsiveness to the arbuscular mycorrhizal fungus Funneliformis mosseae. Following their phenological responses we selected two mutants for a deeper analysis: Green ripe (Gr), deficient in fruit ethylene perception and high-pigment-1 (hp-1), displaying enhanced light signal perception throughout the plant. We investigated the putative interactions between ripening processes, mycorrhizal establishment and systemic effects using biochemical and gene expression tools. Our experiments showed that both mutants, notwithstanding a normal mycorrhizal phenotype at root level, exhibit altered arbuscule functionality. Furthermore, in contrast to wild type, mycorrhization did not lead to a higher phosphate concentration in berries of both mutants. These results suggest that the mutations considered interfere with arbuscular mycorrhiza inducing systemic changes in plant phenology and fruits metabolism. We hypothesize a cross talk mechanism between AM and ripening processes that involves genes related to ethylene and light signaling.

Transcriptomic analysis of swarm motility phenotype of Salmonella enterica serovar Typhimurium mutant defective in periplasmic glucan synthesis

Science.gov (United States)

Movement of food-borne pathogens on moist surfaces enables them to migrate towards more favorable niches and facilitate their survival for extended periods of time. Salmonella enterica serovar Typhimurium mutants defective in OPG synthesis are unable to exhibit motility on moist surfaces (swarming) ...

Genetic Analysis of Streaked and Abnormal Floret Mutant st-fon

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De-xi CHEN

2013-07-01

Full Text Available A double mutant with streaked leaf and abnormal floret was found and temporarily named streaked leaf and floral organ number mutant (st-fon. For this mutant, besides white streak appeared on culm, leaves and panicles, the number of floral organs increased and florets cracked. The extreme phenotype was that several small florets grew from one floret or branch rachis in small florets extended and developed into panicles. By using transmission electron microscope to observe the ultrastructure of white histocytes of leaves at the seedling stage, the white tissues which showed abnormal plastids, lamellas and thylakoids could not develop into normal chloroplast, and the development of chloroplast was blocked at the early growth stage of plastid. Scanning electron microscope and paraffin section were also used to observe the development of floral organs, and the results indicated that the development of floral meristem was out of order and unlimited, whereas in the twisty leaves, vascular bundle sheath cells grew excessively, or some bubbly cells increased. Genetic analyses carried out by means of cross and backcross with four normal-leaf-color materials revealed that the mutant is of cytoplasm inheritance.

Human Lysozyme Synergistically Enhances Bactericidal Dynamics and Lowers the Resistant Mutant Prevention Concentration for Metronidazole to Helicobacter pylori by Increasing Cell Permeability

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Xiaolin Zhang

2016-10-01

Full Text Available Metronidazole (MNZ is an effective agent that has been employed to eradicate Helicobacter pylori (H. pylori. The emergence of broad MNZ resistance in H. pylori has affected the efficacy of this therapeutic agent. The concentration of MNZ, especially the mutant prevention concentration (MPC, plays an important role in selecting or enriching resistant mutants and regulating therapeutic effects. A strategy to reduce the MPC that can not only effectively treat H. pylori but also prevent resistance mutations is needed. H. pylori is highly resistant to lysozyme. Lysozyme possesses a hydrolytic bacterial cell wall peptidoglycan and a cationic dependent mode. These effects can increase the permeability of bacterial cells and promote antibiotic absorption into bacterial cells. In this study, human lysozyme (hLYS was used to probe its effects on the integrity of the H. pylori outer and inner membranes using as fluorescent probe hydrophobic 1-N-phenyl-naphthylamine (NPN and the release of aspartate aminotransferase. Further studies using a propidium iodide staining method assessed whether hLYS could increase cell permeability and promote cell absorption. Finally, we determined the effects of hLYS on the bactericidal dynamics and MPC of MNZ in H. pylori. Our findings indicate that hLYS could dramatically increase cell permeability, reduce the MPC of MNZ for H. pylori, and enhance its bactericidal dynamic activity, demonstrating that hLYS could reduce the probability of MNZ inducing resistance mutations.

Respiratory-deficient mutants of the unicellular green alga Chlamydomonas: a review.

Science.gov (United States)

Salinas, Thalia; Larosa, Véronique; Cardol, Pierre; Maréchal-Drouard, Laurence; Remacle, Claire

2014-05-01

Genetic manipulation of the unicellular green alga Chlamydomonas reinhardtii is straightforward. Nuclear genes can be interrupted by insertional mutagenesis or targeted by RNA interference whereas random or site-directed mutagenesis allows the introduction of mutations in the mitochondrial genome. This, combined with a screen that easily allows discriminating respiratory-deficient mutants, makes Chlamydomonas a model system of choice to study mitochondria biology in photosynthetic organisms. Since the first description of Chlamydomonas respiratory-deficient mutants in 1977 by random mutagenesis, many other mutants affected in mitochondrial components have been characterized. These respiratory-deficient mutants increased our knowledge on function and assembly of the respiratory enzyme complexes. More recently some of these mutants allowed the study of mitochondrial gene expression processes poorly understood in Chlamydomonas. In this review, we update the data concerning the respiratory components with a special focus on the assembly factors identified on other organisms. In addition, we make an inventory of different mitochondrial respiratory mutants that are inactivated either on mitochondrial or nuclear genes. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Root and Nodulation Phenotypes of the Ethylene-Insensitive Sickle Mutant of Medicago truncatula

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JOKO PRAYITNO

2010-09-01

Full Text Available The sickle (skl mutant of the model legume Medicago truncatula is an ethylene-sensitive mutant that have a ten-fold increase in nodule numbers. The nodulation and root phenotypes of the skl mutant were investigated and further characterised. The skl mutant had longer roots than the wild type, but when inoculated with Sinorhizobium, its root length was reduced to the level of wild type. Furthermore, lateral root numbers in uninoculated skl were similar to those in uninoculated wild type. However, when the root tips were decapitated, fewer lateral roots formed in skl than in wild type. Nodule numbers of the skl mutant were significantly reduced by low nitrate concentration (2.5 mM. These results suggest that skl mutant has alterations in both root and nodule development.

Genetic fingerprinting of mutant rose cultivars

Energy Technology Data Exchange (ETDEWEB)

Kumar, S; Prasad, K V; Singh, K P; Singh, A.P. [Division of Floriculture and Landscaping, Indian Agricultural Research Institute, Pusa, New Delhi (India)], E-mail: kvprasad66@gmail.com

2008-07-01

Six rose mutants evolved at the Indian Agricultural Research Institute, New Delhi from four parent cultivars were characterized based on RAPD markers. Contrary to the earlier findings our effort has conclusively proven that the RAPD markers are indeed robust tools to discern the mutants from their parents. Among 40 primers screened, 7 primers produced inconsistent banding pattern. The number of polymorphic bands varied between 4 (OPA 14) and 10 (OPA1) with an average of 6.5 bands per primer. The percentage polymorphism ranged from 62.5 (OPM 9) to 100 percent (OPA 1). Most of the primers produced monomorphic bands between parent and mutant rose cultivars. When primer OPA 2 was used a specific band of 2.5 kb was noticed in mutant cv. Pusa Urmil and cv. Pusa Abhishek but was absent in parent cv. Jantar Mantar. A polymorphic band of 750 bp was noticed in the parent Kiss of Fire and helped in differentiating the parent from its mutant when amplified with OPK 3. Primer OPS 16 produced discriminatory band of 800 bp in mutant cv. Pink Sport of Montezuma while it was absent in its parent cv. Montezuma. Another specific band of 650 bp was present in parent cv. Montezuma and absent in its mutant cv. Pink Sport of Montezuma signifying the uniqueness of the mutant. Primer OPM 5 brought out distinct polymorphism among the parent Jantar Mantar and its three mutants with absence of a specific band of 1.5 kb in the parent. The four parents and 6 mutants were divided into four distinct groups in the Dendogram constructed by UPGMA method. The most genetically similar cultivar among the 10 cultivars analyzed are Montezuma and its pink sport of Montezuma whereas Abhisarika a mutant of cv. Kiss of Fire was distinctly different and formed a separate cluster. (author)

From one body mutant to one cell mutant. A progress of radiation breeding in crops

International Nuclear Information System (INIS)

Nagatomi, Shigeki

1996-01-01

An effective method was established to obtain non-chimeral mutants with wide spectrum of flower colors, regenerated from floral organs on which mutated sectors were come out on chronic irradiated plants. By this way, six mutant varieties of flower colors have been selected from one pink flower of chrysanthemum, and cultivated for cut-flower production. By the same method, 3 mutant varieties with small and spray type flowers were selected in Eustoma. Mutant varieties such as a rust disease resistant in sugarcane, 6 dwarfs in Cytisus and pure-white mushroom in velvet shank have been selected successively for short period. (J.P.N.)

Studies on an X-ray induced crinkled leaf mutant of Trichosanthes anguina L

Energy Technology Data Exchange (ETDEWEB)

Datta, Subodh Kumar

1986-06-01

Crinkled leaf mutant isolated in the second generation after treatment with X-ray bred true in subsequent generation. The mutant was a late flowering type with increased percentage of PMC's with chromosomal abnormality and pollen grain sterility. TLC study on phenolic compounds in leaves showed that both the mother line and the mutant had equal number of spots but they differed from each other with respect to four spots. Spot Nos. 2 and 4 of the mother line were absent in the mutant but the latter had two new spots (spot Nos. 11 and 12). The mutant and the mother line also differed from each other in pollen grain morohology. 3 figures, 2 tables, 4 refs.

The Arabidopsis defence response mutant esa1 as a tool to discover novel resistance traits against Fusarium diseases

NARCIS (Netherlands)

Hemelrijck, van W.; Wouters, P.F.J.; Brouwer, M.; Windelinckx, A.; Goderis, I.J.W.M.; Bolle, De M.F.C.; Thomma, B.P.H.J.; Cammue, B.P.A.; Delauré, S.L.

2006-01-01

The Arabidopsis thaliana mutant esa1 was previously shown to exhibit enhanced susceptibility to the necrotrophic fungal pathogens Alternaria brassicicola, Botrytis cinerea and Plectosphaerella cucumerina. In this work, we tried to elaborate on this susceptibility by investigating whether the esa1

Nuclear accumulation of SHIP1 mutants derived from AML patients leads to increased proliferation of leukemic cells.

Science.gov (United States)

Nalaskowski, Marcus M; Ehm, Patrick; Rehbach, Christoph; Nelson, Nina; Täger, Maike; Modest, Kathrin; Jücker, Manfred

2018-05-28

The inositol 5-phosphatase SHIP1 acts as negative regulator of intracellular signaling in myeloid cells and is a tumor suppressor in myeloid leukemogenesis. After relocalization from the cytoplasm to the plasma membrane SHIP1 terminates PI3-kinase mediated signaling processes. Furthermore, SHIP1 is also found in distinct puncta in the cell nucleus and nuclear SHIP1 has a pro-proliferative function. Here we report the identification of five nuclear export signals (NESs) which regulate together with the two known nuclear localization signals (NLSs) the nucleocytoplasmic shuttling of SHIP1. Mutation of NLSs reduced the nuclear import and mutation of NESs decreased the nuclear export of SHIP1 in the acute myeloid leukemia (AML) cell line UKE-1. Interestingly, four SHIP1 mutants (K210R, N508D, V684E, Q1153L) derived from AML patients showed a nuclear accumulation after expression in UKE-1 cells. In addition, overexpression of the AML patient-derived mutation N508D caused an increased proliferation rate of UKE-1 cells in comparison to wild type SHIP1. Furthermore, we identified serine and tyrosine phosphorylation as a molecular mechanism for the regulation of nucleocytoplasmic shuttling of SHIP1 where tyrosine phosphorylation of distinct residues i.e. Y864, Y914, Y1021 reduces nuclear localization, whereas serine phosphorylation at S933 enhances nuclear localization of SHIP1. In summary, our data further implicate nuclear SHIP1 in cellular signaling and suggest that enhanced accumulation of SHIP1 mutants in the nucleus may be a contributory factor of abnormally high proliferation of AML cells. Copyright © 2017. Published by Elsevier Inc.

Hemophilia B with mutations at glycine-48 of factor IX exhibited delayed activation by the factor VIIa-tissue factor complex.

Science.gov (United States)

Wu, P C; Hamaguchi, N; Yu, Y S; Shen, M C; Lin, S W

2000-10-01

Gly-48 is in the conserved DGDQC sequence (residues 47-51 of human factor IX) of the first EGF (EGF-1)-like domain of factor IX. The importance of the Gly-48 is manifested by two hemophilia B patients; factor IXTainan and factor IXMalmo27, with Gly-48 replaced by arginine (designated IXG48R) and valine (IXG48V), respectively. Both patients were CRM+ exhibiting mild hemophilic episodes with 25% (former) and 19% (latter) normal clotting activities. We characterize both factor IX variants to show the roles of Gly-48 and the conservation of the DGDQC sequence in factor IX. Purified plasma and recombinant factor IX variants exhibited approximately 26%-27% normal factor IX's clotting activities with G48R or G48V mutation. Both variants depicted normal quenching of the intrinsic fluorescence by increasing concentrations of calcium ions and Tb3+, indicating that arginine and valine substitution for Gly-48 did not perturb the calcium site in the EGF-1 domain. Activation of both mutants by factor XIa appeared normal. The reduced clotting activity of factors IXG48R and IXG48V was attributed to the failure of both mutants to cleavage factor X: in the presence of only phospholipids and calcium ions, both mutants showed a 4 to approximately 7-fold elevation in Km, and by adding factor VIIIa to the system, although factor VIIIa potentiated the activation of factor X by the mutants factor IXaG48R and factor IXaG48V, a 2 to approximately 3-fold decrease in the catalytic function was observed with the mutant factor IXa's, despite that they bound factor VIIIa on the phospholipid vesicles with only slightly reduced affinity when compared to wild-type factor IXa. The apparent Kd for factor VIIIa binding was 0.83 nM for normal factor IXa, 1.74 nM for IXaG48R and 1.4 nM for IXaG48V. Strikingly, when interaction with the factor VIIa-TF complex was examined, both mutations were barely activated by the VIIa-TF complex and they also showed abnormal interaction with VIIa-TF in bovine

Officially released mutant varieties - the FAO/IAEA Database

International Nuclear Information System (INIS)

Maluszynski, M.; Nichterlein, K.; Zanten, L. van; Ahloowalia, B.S.

2000-01-01

In the approximately 70 year-old history of induced mutations, there are many examples on the development of new and valuable alteration in plant characters significantly contributing to increased yield potential of specific crops. However, knowledge on the success of induced mutations in crop improvement among geneticists and breeders is usually limited to species of their interest. The present paper contains a comprehensive list of officially released mutant varieties, based on information from plant breeders. The number of mutant varieties officially released and recorded in the FAO/IAEA Mutant Varieties Database before the end of 2000 is 2,252. Almost half of these varieties have been released during the last 15 years. Considering a significant delay in the dissemination of information on newly released varieties and difficulties in the collection of such data, there has been a renaissance in the use of mutation techniques in crop improvement. At the demand of geneticists, plant breeders, and more recently molecular geneticists, for information on released mutant varieties of specific crops, the MVD was transferred to the web site of the FAO/IAEA Joint Division. The MVD will be available on our web pages early in 2001. (author)

Leaf and canopy photosynthesis of a chlorophyll deficient soybean mutant.

Science.gov (United States)

Sakowska, Karolina; Alberti, Giorgio; Genesio, Lorenzo; Peressotti, Alessandro; Delle Vedove, Gemini; Gianelle, Damiano; Colombo, Roberto; Rodeghiero, Mirco; Panigada, Cinzia; Juszczak, Radosław; Celesti, Marco; Rossini, Micol; Haworth, Matthew; Campbell, Benjamin W; Mevy, Jean-Philippe; Vescovo, Loris; Cendrero-Mateo, M Pilar; Rascher, Uwe; Miglietta, Franco

2018-03-02

The photosynthetic, optical, and morphological characteristics of a chlorophyll-deficient (Chl-deficient) "yellow" soybean mutant (MinnGold) were examined in comparison with 2 green varieties (MN0095 and Eiko). Despite the large difference in Chl content, similar leaf photosynthesis rates were maintained in the Chl-deficient mutant by offsetting the reduced absorption of red photons by a small increase in photochemical efficiency and lower non-photochemical quenching. When grown in the field, at full canopy cover, the mutants reflected a significantly larger proportion of incoming shortwave radiation, but the total canopy light absorption was only slightly reduced, most likely due to a deeper penetration of light into the canopy space. As a consequence, canopy-scale gross primary production and ecosystem respiration were comparable between the Chl-deficient mutant and the green variety. However, total biomass production was lower in the mutant, which indicates that processes other than steady state photosynthesis caused a reduction in biomass accumulation over time. Analysis of non-photochemical quenching relaxation and gas exchange in Chl-deficient and green leaves after transitions from high to low light conditions suggested that dynamic photosynthesis might be responsible for the reduced biomass production in the Chl-deficient mutant under field conditions. © 2018 John Wiley & Sons Ltd.

Induction of Mutants in Durum Wheat

International Nuclear Information System (INIS)

AL-Ubaidi, M.; Ibrahim, I.; AL-Hadithi, A.

2002-01-01

This investigation presents a breeding program for induction and development of a new genotype of durum wheat, resistant to lodging with high yield, by irradiation durum wheat hybrids (F2) with gamma rays 100 Gy, during 1990-1997 cultivation seasons. This program involves: induction of variability, selection evaluation of the mutants at three locations: Twaitha (Baghdad) Latifya ( Babylon) and Swari (Kutt). All mutants showed resistance to lodging and there was a significant reduction in plant height. Mutant SIXIZ-22 surpassed other mutants and its origin in lodging resistance and plant height (83.5,82.8 and 89.4 cm) in the three locations at generation M5 and M6, respectively. Also, there were significant differences between mutant and their origin in the number of spikes/M 2 and grain yild during the two successive generation. On the other hand, mutant IZxCO-105 surpassed other mutants in the number of spikes/M 2 (231.8,242.3 and 292) and grain yield (4336,3376 and 5232 kg/ha) in all testing location, respectively . (authors) 14 refs., 4 tabs

Clavulanic acid production by the MMS 150 mutant obtained from wild type Streptomyces clavuligerus ATCC 27064

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Eliton da Silva Vasconcelos

2013-12-01

Full Text Available Clavulanic acid (CA is a powerful inhibitor of the beta-lactamases, enzymes produced by bacteria resistants to penicillin and cefalosporin. This molecule is produced industrially by strains of Streptomyces clavuligerus in complex media which carbon and nitrogen resources are supplied by inexpensive compounds still providing high productivity. The genetic production improvement using physical and chemical mutagenic agents is an important strategy in programs of industrial production development of bioactive metabolites. However, parental strains are susceptible to loss of their original productivity due genetic instability phenomenona. In this work, some S. clavuligerus mutant strains obtained by treatment with UV light and with MMS are compared with the wild type (Streptomyces clavuligerus ATCC 27064. The results indicated that the random mutations originated some strains with different phenotypes, most divergent demonstrated by the mutants strains named AC116, MMS 150 and MMS 54, that exhibited lack of pigmentation in their mature spores. Also, the strain MMS 150 presented a larger production of CA when cultivated in semi-synthetics media. Using other media, the wild type strain obtained a larger CA production. Besides, using the modifed complex media the MMS 150 strain showed changes in its lipolitic activity and a larger production of CA. The studies also allowed finding the best conditions for a lipase activity exhibited by wild type S. clavuligerus and the MMS150 mutant.

Clavulanic acid production by the MMS 150 mutant obtained from wild type Streptomyces clavuligerus ATCC 27064.

Science.gov (United States)

da Silva Vasconcelos, Eliton; de Lima, Vanderlei Aparecido; Goto, Leandro Seiji; Cruz-Hernández, Isara Lourdes; Hokka, Carlos Osamu

2013-12-01

Clavulanic acid (CA) is a powerful inhibitor of the beta-lactamases, enzymes produced by bacteria resistants to penicillin and cefalosporin. This molecule is produced industrially by strains of Streptomyces clavuligerus in complex media which carbon and nitrogen resources are supplied by inexpensive compounds still providing high productivity. The genetic production improvement using physical and chemical mutagenic agents is an important strategy in programs of industrial production development of bioactive metabolites. However, parental strains are susceptible to loss of their original productivity due genetic instability phenomenona. In this work, some S. clavuligerus mutant strains obtained by treatment with UV light and with MMS are compared with the wild type (Streptomyces clavuligerus ATCC 27064). The results indicated that the random mutations originated some strains with different phenotypes, most divergent demonstrated by the mutants strains named AC116, MMS 150 and MMS 54, that exhibited lack of pigmentation in their mature spores. Also, the strain MMS 150 presented a larger production of CA when cultivated in semi-synthetics media. Using other media, the wild type strain obtained a larger CA production. Besides, using the modifed complex media the MMS 150 strain showed changes in its lipolitic activity and a larger production of CA. The studies also allowed finding the best conditions for a lipase activity exhibited by wild type S. clavuligerus and the MMS150 mutant.

Mutants with Enhanced Nitrogenase Activity in Hydroponic Azospirillum brasilense-Wheat Associations

Science.gov (United States)

Pereg Gerk, Lily; Gilchrist, Kate; Kennedy, Ivan R.

2000-01-01

The effect of a mutation affecting flocculation, differentiation into cyst-like forms, and root colonization on nitrogenase expression by Azospirillum brasilense is described. The gene flcA of strain Sp7 restored these phenotypes in spontaneous mutants of both strains Sp7 and Sp245. Employing both constitutive pLA-lacZ and nifH-lacZ reporter fusions expressed in situ, the colony morphology, colonization pattern, and potential for nitrogenase activity of spontaneous mutants and flcA Tn5-induced mutants were established. The results of this study show that the ability of Sp7 and Sp245 mutant strains to remain in a vegetative form improved their ability to express nitrogenase activity in association with wheat in a hydroponic system. Restoring the cyst formation and colonization pattern to the spontaneous mutant Sp7-S reduced nitrogenase activity rates in association with plants to that of the wild-type Sp7. Although Tn5-induced flcA mutants showed higher potentials for nitrogenase expression than Sp7, their potentials were lower than that of Sp7-S, indicating that other factors in this strain contribute to its exceptional nitrogenase activity rates on plants. The lack of lateral flagella is not one of these factors, as Sp7-PM23, a spontaneous mutant impaired in swarming and lateral-flagellum production but not in flocculation, showed wild-type nitrogenase activity and expression. The results also suggest factors of importance in evolving an effective symbiosis between Azospirillum and wheat, such as increasing the availability of microaerobic niches along the root, increased supply of carbon sources by the plant, and the retention of the bacterial cells in vegetative form for faster metabolism. PMID:10788397

A detailed study of gerJ mutants of Bacillus subtilis.

Science.gov (United States)

Warburg, R J; Buchanan, C E; Parent, K; Halvorson, H O

1986-08-01

A total of nine gerJ mutants have now been isolated in Bacillus subtilis. All are defective in their spore germination properties, being blocked at an intermediate (phase grey) stage. The dormant spores are sensitive to heating at 90 degrees C and two of the mutants (generated by transposon insertion) produce spores sensitive at 80 degrees C. The spores of these two more extreme mutants had a visibly defective cortex when studied by electron microscopy, as did some of the other mutants. During sporulation, the acquisition of spore resistance properties and the appearance of the sporulation-specific penicillin-binding protein PBP5* were delayed. A strain probably carrying a lacZ fusion to the gerJ promoter demonstrated increased expression between t2 and t4. We propose that the gerJ locus is involved in the control of one or more sporulation-specific genes.

Gamma rays induced bold seeded high yielding mutant in chickpea

International Nuclear Information System (INIS)

Wani, A.A.; Anis, M.

2001-01-01

variety (12.64±0.14g). This ultimately resulted in an increase in the overall yield of the mutant plant (38.86±1.69g) as compared to Pusa-212 (30.05±0.59g). Gamma ray induced bold seeded mutants have been reported earlier by different workers. The decrease in the number of seeds per pod and pods/plant and increase in seed weight is evidence of the fact that each trait is affected independently by the mutagenic treatment. Although the mutant was morphologically distinct, cytologically it was normal. There were 8 perfect bivalents at metaphase and the anaphase segregation was normal. It is concluded that bold seeded mutant may be utilized in various breeding programs as a donor parent for boldness character of the mutant. On the other hand the mutant may also itself be improved through crosses with other parents to accommodate more seeds in its large sized pod, which remained almost 50% empty

Influence of ultraviolet light on arising of induced mutants in Cercospora beticola sacc

Energy Technology Data Exchange (ETDEWEB)

Brillova, D [Institute of Experimental Phytopathology and Entomology of the Slovak Academy of Sciences, Ivanka pri Dunaji (Czechoslovakia)

1976-01-01

Ultraviolet radiation of wavelengths of 254 and 350 nm respectively, applied for 30 to 480 seconds to the conidia of Cercospora beticola, induced a large number of mutants. According to their appearance, the occurring mutants can be considered as visible with effect on morphology and colour. A considerable part of the mutants lost its ability to form reproductive organs in in vitro conditions, as well as on the host plant; they became avirulent. Moreover, mutants occurred with decreased virulence, with a weak forming of conidia and prolonged incubation period. In few cases, also reverse mutations were induced characterized by increased virulence.

Andrographolide induces degradation of mutant p53 via activation of Hsp70.

Science.gov (United States)

Sato, Hirofumi; Hiraki, Masatsugu; Namba, Takushi; Egawa, Noriyuki; Baba, Koichi; Tanaka, Tomokazu; Noshiro, Hirokazu

2018-05-22

The tumor suppressor gene p53 encodes a transcription factor that regulates various cellular functions, including DNA repair, apoptosis and cell cycle progression. Approximately half of all human cancers carry mutations in p53 that lead to loss of tumor suppressor function or gain of functions that promote the cancer phenotype. Thus, targeting mutant p53 as an anticancer therapy has attracted considerable attention. In the current study, a small-molecule screen identified andrographlide (ANDRO) as a mutant p53 suppressor. The effects of ANDRO, a small molecule isolated from the Chinese herb Andrographis paniculata, on tumor cells carrying wild-type or mutant p53 were examined. ANDRO suppressed expression of mutant p53, induced expression of the cyclin-dependent kinase inhibitor p21 and pro-apoptotic proteins genes, and inhibited the growth of cancer cells harboring mutant p53. ANDRO also induced expression of the heat-shock protein (Hsp70) and increased binding between Hsp70 and mutant p53 protein, thus promoting proteasomal degradation of p53. These results provide novel insights into the mechanisms regulating the function of mutant p53 and suggest that activation of Hsp70 may be a new strategy for the treatment of cancers harboring mutant p53.

Root hair mutants of barley

International Nuclear Information System (INIS)

Engvild, K.C.; Rasmussen, K.

2005-01-01

Barley mutants without root hairs or with short or reduced root hairs were isolated among M 2 seeds of 'Lux' barley (Hordeum vulgare L.) after acidified sodium azide mutagenesis. Root hair mutants are investigated intensively in Arabidopsis where about 40 genes are known. A few root hair mutants are known in maize, rice, barley and tomato. Many plants without root hairs grow quite well with good plant nutrition, and mutants have been used for investigations of uptake of strongly bound nutrients like phosphorus, iron, zinc and silicon. Seed of 'Lux' barley (Sejet Plant Breeding, Denmark) were soaked overnight, and then treated with 1.5-millimolarsodium azide in 0.1 molar sodium phosphate buffer, pH 3, for 2.5 hours according to the IAEA Manual on Mutation Breeding (2nd Ed.). After rinsing in tap water and air-drying, the M 2 seeds were sown in the field the same day. Spikes, 4-6 per M 1 plant, were harvested. The mutation frequency was similar to that obtained with other barley cultivars from which low-phytate mutants were isolated [5]. Seeds were germinated on black filter paper in tap water for 3 or 4 days before scoring for root hair mutants

Effect of CCS on the accumulation of FALS SOD1 mutant-containing aggregates and on mitochondrial translocation of SOD1 mutants: implication of a free radical hypothesis.

Science.gov (United States)

Kim, Ha Kun; Chung, Youn Wook; Chock, P Boon; Yim, Moon B

2011-05-15

Missense mutations of SOD1 are linked to familial amyotrophic lateral sclerosis (FALS) through a yet-to-be identified toxic-gain-of-function. One of the proposed mechanisms involves enhanced aggregate formation. However, a recent study showed that dual transgenic mice overexpressing both G93A and CCS copper chaperone (G93A/CCS) exhibit no SOD1-positive aggregates yet show accelerated FALS symptoms with enhanced mitochondrial pathology compared to G93A mice. Using a dicistronic mRNA to simultaneously generate hSOD1 mutants, G93A, A4V and G85R, and hCCS in AAV293 cells, we revealed: (i) CCS is degraded primarily via a macroautophagy pathway. It forms a stable heterodimer with inactive G85R, and via its novel copper chaperone-independent molecular chaperone activity facilitates G85R degradation via a macroautophagy-mediated pathway. For active G93A and A4V, CCS catalyzes their maturation to form active and soluble homodimers. (ii) CCS reduces, under non-oxidative conditions, yet facilitates in the presence of H(2)O(2), mitochondrial translocation of inactive SOD1 mutants. These results, together with previous reports showing FALS SOD1 mutants enhanced free radical-generating activity, provide a mechanistic explanation for the observations with G93A/CCS dual transgenic mice and suggest that free radical generation by FALS SOD1, enhanced by CCS, may, in part, be responsible for the FALS SOD1 mutant-linked aggregation, mitochondrial translocation, and degradation. Published by Elsevier Inc.

Induced high yielding mutant in green gram (Vigna radiata (L.) Wilczek)

International Nuclear Information System (INIS)

Pulivarthi, H.R.; Mary, T.N.

1987-01-01

Green gram (mungbean) plays a significant role in meeting the protein requirements in India, with its predominantly vegetarian population. Therefore, an attempt was made to induce desirable mutants. Dry seed of cultivar 'Pusa 105' were irradiated with gamma rays ranging from 10 to 50 krad. A high yielding mutant (Hy I) identified in the M 4 generation from 40 krad dose, has shown significant increases in the number of pods/plants, number of branches/plant, and yield/plant. Further work is in progress. Comparison of the mutant HyI with the parent cultivar Pusa 105 is given

Evaluation of semi-dwarf mutants in triticale and wheat breeding programmes

International Nuclear Information System (INIS)

Driscoll, C.J.

1982-01-01

A number of short-statured triticale plants were selected in M 4 following gamma-ray or EMS treatment of seed of Beagle and DR-IRA triticales. Selection for homozygous mutants will be attempted in M 5 . The Cornerstone male sterility mutant mslc is being combined with the three GA-insensitive, reduced-height mutants Gai/Rht1, Gai/Rht2 and Gai/Rht3 in order to establish a composite cross based on homozygosity of a given Gai/Rht allele. This would allow selection for minor genes for increased height on a GA-insensitive, reduced-height background. (author)

A Constitutively Mannose-Sensitive Agglutinating Salmonella enterica subsp. enterica Serovar Typhimurium Strain, Carrying a Transposon in the Fimbrial Usher Gene stbC, Exhibits Multidrug Resistance and Flagellated Phenotypes

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Kuan-Hsun Wu

2012-01-01

Full Text Available Static broth culture favors Salmonella enterica subsp. enterica serovar Typhimurium to produce type 1 fimbriae, while solid agar inhibits its expression. A transposon inserted in stbC, which would encode an usher for Stb fimbriae of a non-flagellar Salmonella enterica subsp. enterica serovar Typhimurium LB5010 strain, conferred it to agglutinate yeast cells on both cultures. RT-PCR revealed that the expression of the fimbrial subunit gene fimA, and fimZ, a regulatory gene of fimA, were both increased in the stbC mutant when grown on LB agar; fimW, a repressor gene of fimA, exhibited lower expression. Flagella were observed in the stbC mutant and this phenotype was correlated with the motile phenotype. Microarray data and RT-PCR indicated that the expression of three genes, motA, motB, and cheM, was enhanced in the stbC mutant. The stbC mutant was resistant to several antibiotics, consistent with the finding that expression of yhcQ and ramA was enhanced. A complementation test revealed that transforming a recombinant plasmid possessing the stbC restored the mannose-sensitive agglutination phenotype to the stbC mutant much as that in the parental Salmonella enterica subsp. enterica serovar Typhimurium LB5010 strain, indicating the possibility of an interplay of different fimbrial systems in coordinating their expression.

Induction of mutagenized tomato populations for investigation on agronomic traits and mutant phenotyping

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Rafiul Amin Laskar

2018-01-01

Full Text Available Global demand for tomato production increased tremendously due to its diverse utility in raw, cooked and processed form of food. This necessitates the continued supply of highly nutritious and better yielding improved cultivars to the producers, considering the rapid changing agro-climatic condition. In this study, induced mutant tomato populations of widely recommended tomato genotype Arka Vikas (Sel-22 were generated using chemical mutagen ethyl methane sulfonate (EMS, hydrazine hydrates (HZ and their combined treatments. In the in vitro study, a gradual reduction in germination percentage and seedling height occurred with the increasing concentrations of mutagens. Combination of EMS and HZ caused maximum biological inhibition followed by EMS and HZ treatments alone in M1 generation. The rate of survival and fertility in M1 plants of tomato was found highly affected due to mutagenic treatment, in which sensitivity toward combined treatment was found highest followed by EMS and HZ. Inspection on induced phenotypic variations in individual plants of M2 population resulted in identification and isolation of wide range of mutants with altered phenotypes. Highest mutation frequency was resulted by combined mutagens followed by the EMS and HZ treatment. Agronomic trait analyses showed intra and inter treatment variations in three quantitative traits (Plant height, fertile branch per plant and fruits per plant of M2 mutagenized population. Assessment on rate of mutant recovery in M2 population showed highest mutant recovery is possible with combination treatments and then 0.02% HZ followed by 0.02% EMS. In the present study, phenotyping of the mutants revealed that vegetative organs (‘plant size’, ‘plant habit’ and ‘leaf morphology’ was the most sensitive category (69.33% to which most of the mutant belongs, followed by ‘fruit color and size’ (20.27% and ‘germination’ (9.79%. Comparative investigation on number of mutants and

Herpes simplex virus type 1 gene UL14: phenotype of a null mutant and identification of the encoded protein.

Science.gov (United States)

Cunningham, C; Davison, A J; MacLean, A R; Taus, N S; Baines, J D

2000-01-01

Herpes simplex virus type 1 (HSV-1) gene UL14 is located between divergently transcribed genes UL13 and UL15 and overlaps the promoters for both of these genes. UL14 also exhibits a substantial overlap of its coding region with that of UL13. It is one of the few HSV-1 genes for which a phenotype and protein product have not been described. Using mass spectrometric and immunological approaches, we demonstrated that the UL14 protein is a minor component of the virion tegument of 32 kDa which is expressed late in infection. In infected cells, the UL14 protein was detected in the nucleus at discrete sites within electron-dense nuclear bodies and in the cytoplasm initially in a diffuse distribution and then at discrete sites. Some of the UL14 protein was phosphorylated. A mutant with a 4-bp deletion in the central region of UL14 failed to produce the UL14 protein and generated small plaques. The mutant exhibited an extended growth cycle at low multiplicity of infection and appeared to be compromised in efficient transit of virus particles from the infected cell. In mice injected intracranially, the 50% lethal dose of the mutant was reduced more than 30,000-fold. Recovery of the mutant from the latently infected sacral ganglia of mice injected peripherally was significantly less than that of wild-type virus, suggesting a marked defect in the establishment of, or reactivation from, latent infection.

Comparative production of cellulases by mutants of Trichoderma parceramosume PTCC5140

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Hoda Nouri

2017-06-01

Discussion and conclusion: Evaluation of cellulase production in mutant strains of Trichoderma parceramosume PTCC 5140 showed that use of chemical mutagenesis with 2 to 11 fold increasing in enzyme activity is a potent method to improve cellulase complex activity. In the current study, obtained mutant strains could be introduced as a potent cellulase producer for further studies in bioconversion processes.

A New Bacillus licheniformis Mutant Strain Producing Serine Protease Efficient for Hvdrolvqis of Sov Meal Proteins.

Science.gov (United States)

Kostyleva, E V; Sereda, A S; Velikoretskaya, I A; Nefedova, L I; Sharikov, A Yu; Tsurikova, N V; Lobanov, N S; Semenova, M V; Sinitsyn, A P

2016-07-01

Induced mutagenesis with y-irradiation of the industrial strain Bacillus licheniformis-60 VKM B-2366,D was used to obtain a new highly active producer of an extracellular serine protease, Bacillus licheni- formis7 145. Samples of dry.concentrated preparations of serine protease produced by the original and mutant strains were obtained, and identity of their protein composition was'established. Alkaline serine protease sub- tilisin DY was the main component of the preparations. The biochemical and physicochemical properties of the Protolkheterm-145 enzyme preparation obtained from the mutant strain were studied. It exhibited pro- teolytic activity (1.5 times higher than the preparation from the initial strain) within broad ranges of pH (5- 11) and temperature (30-70'C).-Efficient hydrolysis of extruded soy meal protein at high concentrations (2 to 50%) in-the reaction mixture was.the main advantage of the Protolikheterm 145 preparation. Compared to,. the preparation obtained using the initial strain, the new preparation with increased proteolytic-activity pro- vided for more complete hydrolysis of the main non-nutritious soy,proteins.(glycinin and 0-conglycinin) with the yield of soluble protein increased by 19-28%, which decreased the cost of bioconversion of the protein- aceous material and indicated promise of the new preparation in resource-saving technologies for processing soy meals and cakes.

A Medicago truncatula Tobacco Retrotransposon Insertion Mutant Collection with Defects in Nodule Development and Symbiotic Nitrogen Fixation1[W][OA

Science.gov (United States)

Pislariu, Catalina I.; D. Murray, Jeremy; Wen, JiangQi; Cosson, Viviane; Muni, RajaSekhara Reddy Duvvuru; Wang, Mingyi; A. Benedito, Vagner; Andriankaja, Andry; Cheng, Xiaofei; Jerez, Ivone Torres; Mondy, Samuel; Zhang, Shulan; Taylor, Mark E.; Tadege, Million; Ratet, Pascal; Mysore, Kirankumar S.; Chen, Rujin; Udvardi, Michael K.

2012-01-01

A Tnt1-insertion mutant population of Medicago truncatula ecotype R108 was screened for defects in nodulation and symbiotic nitrogen fixation. Primary screening of 9,300 mutant lines yielded 317 lines with putative defects in nodule development and/or nitrogen fixation. Of these, 230 lines were rescreened, and 156 lines were confirmed with defective symbiotic nitrogen fixation. Mutants were sorted into six distinct phenotypic categories: 72 nonnodulating mutants (Nod−), 51 mutants with totally ineffective nodules (Nod+ Fix−), 17 mutants with partially ineffective nodules (Nod+ Fix+/−), 27 mutants defective in nodule emergence, elongation, and nitrogen fixation (Nod+/− Fix−), one mutant with delayed and reduced nodulation but effective in nitrogen fixation (dNod+/− Fix+), and 11 supernodulating mutants (Nod++Fix+/−). A total of 2,801 flanking sequence tags were generated from the 156 symbiotic mutant lines. Analysis of flanking sequence tags revealed 14 insertion alleles of the following known symbiotic genes: NODULE INCEPTION (NIN), DOESN’T MAKE INFECTIONS3 (DMI3/CCaMK), ERF REQUIRED FOR NODULATION, and SUPERNUMERARY NODULES (SUNN). In parallel, a polymerase chain reaction-based strategy was used to identify Tnt1 insertions in known symbiotic genes, which revealed 25 additional insertion alleles in the following genes: DMI1, DMI2, DMI3, NIN, NODULATION SIGNALING PATHWAY1 (NSP1), NSP2, SUNN, and SICKLE. Thirty-nine Nod− lines were also screened for arbuscular mycorrhizal symbiosis phenotypes, and 30 mutants exhibited defects in arbuscular mycorrhizal symbiosis. Morphological and developmental features of several new symbiotic mutants are reported. The collection of mutants described here is a source of novel alleles of known symbiotic genes and a resource for cloning novel symbiotic genes via Tnt1 tagging. PMID:22679222

Isozyme differences in barley mutants

International Nuclear Information System (INIS)

AI-Jibouri, A.A.M.; Dham, K.M.

1990-01-01

Full text: Thirty mutants (M 11 ) of barley (Hordeum vulgare L.) induced by physical and chemical mutagens were analysed for isozyme composition using polyacrylamide gel electrophoresis. Results show that these mutants were different in the isozymes leucine aminopeptidase, esterase and peroxidase. The differences included the number of forms of each enzyme, relative mobility value and their intensity on the gel. Glutamate oxaloacetate transaminase isozyme was found in six molecular forms and these forms were similar in all mutants. (author)

Mutant HFE H63D Protein Is Associated with Prolonged Endoplasmic Reticulum Stress and Increased Neuronal Vulnerability*

Science.gov (United States)

Liu, Yiting; Lee, Sang Y.; Neely, Elizabeth; Nandar, Wint; Moyo, Mthabisi; Simmons, Zachary; Connor, James R.

2011-01-01

A specific polymorphism in the hemochromatosis (HFE) gene, H63D, is over-represented in neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer disease. Mutations of HFE are best known as being associated with cellular iron overload, but the mechanism by which HFE H63D might increase the risk of neuron degeneration is unclear. Here, using an inducible expression cell model developed from a human neuronal cell line SH-SY5Y, we reported that the presence of the HFE H63D protein activated the unfolded protein response (UPR). This response was followed by a persistent endoplasmic reticulum (ER) stress, as the signals of UPR sensors attenuated and followed by up-regulation of caspase-3 cleavage and activity. Our in vitro findings were recapitulated in a transgenic mouse model carrying Hfe H67D, the mouse equivalent of the human H63D mutation. In this model, UPR activation was detected in the lumbar spinal cord at 6 months then declined at 12 months in association with increased caspase-3 cleavage. Moreover, upon the prolonged ER stress, the number of cells expressing HFE H63D in early apoptosis was increased moderately. Cell proliferation was decreased without increased cell death. Additionally, despite increased iron level in cells carrying HFE H63D, it appeared that ER stress was not responsive to the change of cellular iron status. Overall, our studies indicate that the HFE H63D mutant protein is associated with prolonged ER stress and chronically increased neuronal vulnerability. PMID:21349849

Isolation of UV-sensitive mutants of mouse L5178Y cells by a cell suspension spotting method

International Nuclear Information System (INIS)

Shiomi, T.; Hieda-Shiomi, N.; Sato, K.

1982-01-01

We have isolated 56 UV-sensitive mutant clones from a mouse L51 T/t line of L5178Y cells by a cell suspension spotting method. Five mutants have also been isolated from L51 T/t and L5178Y cells by the method reported by Thompson and coworkers. We divided the mutants into two groups, highly sensitive and moderately sensitive mutants, according to their sensitivity to UV irradiation. Fifty-eight mutants were highly sensitive and three were moderately sensitive to UV. The reconstruction experiments indicate that more than 90% of highly sensitive mutants were recovered by the cell suspension spotting method. Frequencies of recovered mutants highly sensitive to UV increased with increasing dose of mutagens. Recovered mutant frequency reached 10(-2) after treatment with 1.5 micrograms/ml of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) (survival 0.2%). Eight UV-sensitive mutants were divided into four complementation groups. These mutants were 2-6 times more sensitive to UV than parental L51 T/t cells in terms of D37 (dose required to reduce survival to 37%). Four representative UV-sensitive mutants which are classified into different complementation groups were examined for their sensitivity to killing by UV, 4-nitroquinoline-1-oxide (4NQO), mitomycin C (MMC), X-rays, and MNNG. All four classes of mutants were found to be cross-sensitive to UV, 4NQO, and MMC, but not sensitive to X-rays and MNNG

Induction of diphtheria toxin-resistant mutants in human cells by ultraviolet light

International Nuclear Information System (INIS)

Rocchi, P.; Ferreri, A.M.; Capucci, A.; Prodi, G.

1981-01-01

Stable spontaneous mutants resistant to the protein synthesis inhibitor diphtheria toxin (DT) have been selected in human cell line EUE at a very low frequency (less than 8 x 10(-6)). U.v.-induced mutation has been quantitatively measured: treatment of cells with u.v. light increased the frequencies of diphtheria toxin resistant (DTr) mutants up to 1000-fold. The maximum recovery of DTr mutants was observed after a short expression period, for all u.v. doses tested, and was followed by a decrease in mutation frequency on subsequent passages

Induction of diphtheria toxin-resistant mutants in human cells by ultraviolet light

International Nuclear Information System (INIS)

Rocchi, P.; Ferreri, A.M.; Capucci, A.; Prodi, G.

1981-01-01

Stable spontaneous mutants resistant to the protein synthesis inhibitor diphtheria toxin (DT) have been selected in human cell line EUE at a very low frequency ( -6 ). U.v.-induced mutation has been quantitatively measured: treatment of cells with u.v. light increased the frequencies of diphtheria toxin resistant (DTsup(r)) mutants up to 1000-fold. The maximum recovery of DTsup(r) mutants was observed after a short expression period, for all u.v. doses tested, and was followed by a decrease in mutation frequency on subsequent passages. (author)

Isozyme differences in barley mutants

Energy Technology Data Exchange (ETDEWEB)

AI-Jibouri, A A.M.; Dham, K M [Department of Botany, Nuclear Research Centre, Baghdad (Iraq)

1990-01-01

Full text: Thirty mutants (M{sub 11}) of barley (Hordeum vulgare L.) induced by physical and chemical mutagens were analysed for isozyme composition using polyacrylamide gel electrophoresis. Results show that these mutants were different in the isozymes leucine aminopeptidase, esterase and peroxidase. The differences included the number of forms of each enzyme, relative mobility value and their intensity on the gel. Glutamate oxaloacetate transaminase isozyme was found in six molecular forms and these forms were similar in all mutants. (author)

Indy mutants: live long and prosper

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Stewart eFrankel

2012-02-01

Full Text Available Indy encodes the fly homologue of a mammalian transporter of di and tricarboxylatecomponents of the Krebs cycle. Reduced expression of fly Indy or two of the C. elegansIndy homologs leads to an increase in life span. Fly and worm tissues that play key roles inintermediary metabolism are also the places where Indy genes are expressed. One of themouse homologs of Indy (mIndy is mainly expressed in the liver. It has been hypothesizedthat decreased INDY activity creates a state similar to caloric restriction (CR. Thishypothesis is supported by the physiological similarities between Indy mutant flies on highcalorie food and control flies on CR, such as increased physical activity and decreases inweight, egg production, triglyceride levels, starvation resistance, and insulin signaling. Inaddition, Indy mutant flies undergo changes in mitochondrial biogenesis also observed inCR animals. Recent findings with mIndy knockout mice support and extend the findingsfrom flies. mIndy-/- mice display an increase in hepatic mitochondrial biogenesis, lipidoxidation and decreased hepatic lipogenesis. When mIndy-/- mice are fed high calorie foodthey are protected from adiposity and insulin resistance. These findings point to INDY as apotential drug target for the treatment of metabolic syndrome, type 2 diabetes and obesity.

Assesment of spineless safflower (Carthamus tinctorius, L.) mutant lines for seed oil content and fatty acid profiles

International Nuclear Information System (INIS)

Ragab, A.I.; Kassem, M.; Moustafa, H.A.M.

2008-01-01

This study was conducted to assess the new spineless mutants that previously induced through gamma radiation and hybridization techniques in the advanced generation for seed oil content and fatty acid profiles The obtained results cleared that oil percentages of all seven safflower mutants were increased than local variety Giza (1) and the new mutant hybrid 2 line (white petals) had the highest increase value of oil percentage (10%) but the mutant line M14 (dark red petals) had the lowest increase value of oil percentage (3.1 %) The mutant line M7 (yellow petals) had the highest value of total saturated fatty acid (40.38%), because it had the highest value of palmitic fatty acid (25.16%), comparing to 10.01% value for local variety Giza (1), followed by mutant line hybrid 2 (white petals) which had (39.88%) because it had the highest value of caprylic, capric, lauric, myristic and stearic fatty acids. All safflower mutant lines had higher value of oleic fatty acid than that of the local variety Giza (1) the two new safflower mutant lines M7 (yellow petals) and hybrid 2 (white petal) had the highest value of oleic fatty acid 41.22% and 39.88% respectively in comparison with 13.5% for local variety Giza (1), the obtained results are indicating to seed oil content negative correlation between oleic and linoleic acids

Auxin-dependent microtubule responses and seedling development are affected in a rice mutant resistant to EPC

International Nuclear Information System (INIS)

Nick, P.; Yatou, O.; Furuya, M.; Lambert, A.M.

1994-01-01

Mutants in rice (Oryza sativa L. cv. japonica) were used to study the role of the cytoskeleton in signal-dependent morphogenesis. Mutants obtained by gamma ray irradiation were selected that failed to show inhibition of coleoptile elongation by the anti microtubular drug ethyl-N-phenylcarbamate (EPC). The mutation EPC-Resistant 31 (ER31), isolated from such a screen, caused lethality in putatively homozygous embryos. Heterozygotes exhibited drug resistance, impaired development of crown roots, and characteristic changes in the pattern of cell elongation: cell elongation was enhanced in mesocotyls and leaf sheaths, but inhibited in coleoptiles. The orientation of cortical microtubules changed correspondingly: for etiolated seedlings, compared with the wild-type, they were more transverse with respect to the long cell axis in mesocotyls and leaf sheaths, but more longitudinal in coleoptiles. In mutant coleoptiles, in contrast to wild-type, microtubules did not reorient in response to auxin, and their response to microtubule-eliminating and microtubule-stabilizing drugs was conspicuously reduced. In contrast, they responded normally to other stimuli such as gibberellins or red light. Auxin sensitivity as assayed by the dose-response for callus induction did not show any significant differences between wild-type and mutant. The mutant phenotype is interpreted in terms of an interrupted link between auxin-triggered signal transduction and microtubule reorientation. (author)

Problem-Solving Test: Tryptophan Operon Mutants

Science.gov (United States)

Szeberenyi, Jozsef

2010-01-01

This paper presents a problem-solving test that deals with the regulation of the "trp" operon of "Escherichia coli." Two mutants of this operon are described: in mutant A, the operator region of the operon carries a point mutation so that it is unable to carry out its function; mutant B expresses a "trp" repressor protein unable to bind…

Thermosensitive mutant of Bacillus subtilis deficient in uracil and cell division

Energy Technology Data Exchange (ETDEWEB)

Nagai, K; Some, H; Tamura, G

1976-01-01

Thermonsensitive division mutants were derived from Bacillus subtilis Marburg 168 thy trp/sub 2/ by means of membrane filtration after nitrosoguanidine mutagenesis. Among them, ts42 requiring uracil for normal growth at 48/sup 0/C was investigated. In the absence of uracil, the mutant cells grew normally at 37/sup 0/C and stopped dividing after temperature shift to 48/sup 0/C resulting in filaments of two to four times length of normal rods. The total cell number after the temperature shift increased two to three fold in 90 min and remained constant thereafter. The viable count after the temperature shift to 48/sup 0/C, increased 1.5 to 2 fold in initial 60 min and then decreased exponentially. A rapid restoration of colony forming ability was shown when the mutant cells were shifted back to the permissive temperature after 120 to 180 min of incubation at 48/sup 0/C or when uracil was introduced to the culture at 48/sup 0/C. This recovery of viability was partly observed even in the presence of chloramphenicol. The synthesis of RNA of this mutant was shown to decline 20 min after the temperature shift to 48/sup 0/C whereas the syntheses of DNA and protein proceeded for more than 80 min at that temperature. No newly isolated uracil requiring mutants formed filaments in the medium lacking uracil or showed growth pattern like ts42.

Exogenous Expressions of FTO Wild-Type and R316Q Mutant Proteins Caused an Increase in HNRPK Levels in 3T3-L1 Cells as Demonstrated by DIGE Analysis

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Nil Guzel

2017-01-01

Full Text Available Fat mass and obesity-associated protein is an enzyme that oxidatively demethylates DNA. Although there are numerous studies regarding the catalytic function of FTO, the overall existence or absence of FTO on cellular proteome has not been investigated. This study investigated the changes in the soluble proteome of 3T3-L1 cells upon expression of the WT and the mutant (R316Q FTO proteins. Protein extracts prepared from 3T3-L1 cells expressing either the WT or the mutant FTO proteins were used in DIGE experiments. Analysis of the data revealed the number of spots matched to every member and there were 350 ± 20 spots with 30.5% overall mean coefficient of variation. Eleven regulated protein spots were excised from the gels and identified by MALDI-TOF/TOF. One of the identified proteins was heterogeneous nuclear ribonucleoprotein K, which displayed more than 2.6- and 3.7-fold increases in its abundance in the WT and the mutant FTO expressing cells, respectively. Western blot analysis validated these observations. This is the first study revealing the presence of a parallel increase in expressions of FTO and HNRNPK proteins. This increase may codictate the metabolic changes occurring in the cell and may attribute a significance to HNRNPK in FTO-associated transformations.

PET imaging of HSV1-tk mutants with acquired specificity toward pyrimidine- and acycloguanosine-based radiotracers

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Likar, Yury; Dobrenkov, Konstantin; Olszewska, Malgorzata; Shenker, Larissa; Hricak, Hedvig; Ponomarev, Vladimir [Memorial Sloan-Kettering Cancer Center, Molecular Imaging Laboratory, Department of Radiology, New York, NY (United States); Cai, Shangde [Memorial Sloan-Kettering Cancer Center, Radiochemistry/Cyclotron Core Facility, New York, NY (United States)

2009-08-15

The aim of this study was to create an alternative mutant of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene with reduced phosphorylation capacity for acycloguanosine derivatives, but not pyrimidine-based compounds that will allow for successful PET imaging. A new mutant of HSV1-tk reporter gene, suitable for PET imaging using pyrimidine-based radiotracers, was developed. The HSV1-tk mutant contains an arginine-to-glutamine substitution at position 176 (HSV1-R176Qtk) of the nucleoside binding region of the enzyme. The mutant-gene product showed favorable enzymatic characteristics toward pyrimidine-based nucleosides, while exhibiting reduced activity with acycloguanosine derivatives. In order to enhance HSV1-R176Qtk reporter activity with pyrimidine-based radiotracers, we introduced the R176Q substitution into the more active HSV1-sr39tk mutant. U87 human glioma cells transduced with the HSV1-R176Qsr39tk double mutant reporter gene showed high {sup 3}H-FEAU pyrimidine nucleoside and low {sup 3}H-penciclovir acycloguanosine analog uptake in vitro. PET imaging also demonstrated high {sup 18}F-FEAU and low {sup 18}F-FHBG accumulation in HSV1-R176Qsr39tk+ xenografts. The feasibility of imaging two independent nucleoside-specific HSV1-tk mutants in the same animal with PET was demonstrated. Two opposite xenografts expressing the HSV1-R176Qsr39tk reporter gene and the previously described acycloguanosine-specific mutant of HSV1-tk, HSV1-A167Ysr39tk reporter gene, were imaged using a short-lived pyrimidine-based {sup 18}F-FEAU and an acycloguanosine-based {sup 18}F-FHBG radiotracer, respectively, administered on 2 consecutive days. We conclude that in combination with acycloguanosine-specific HSV1-A167Ysr39tk reporter gene, a HSV1-tk mutant containing the R176Q substitution could be used for PET imaging of two different cell populations or concurrent molecular biological processes in the same living subject. (orig.)

Abnormalities in brain structure and behavior in GSK-3alpha mutant mice

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Kaidanovich-Beilin Oksana

2009-11-01

Full Text Available Abstract Background Glycogen synthase kinase-3 (GSK-3 is a widely expressed and highly conserved serine/threonine protein kinase encoded by two genes that generate two related proteins: GSK-3α and GSK-3β. Mice lacking a functional GSK-3α gene were engineered in our laboratory; they are viable and display insulin sensitivity. In this study, we have characterized brain functions of GSK-3α KO mice by using a well-established battery of behavioral tests together with neurochemical and neuroanatomical analysis. Results Similar to the previously described behaviours of GSK-3β+/-mice, GSK-3α mutants display decreased exploratory activity, decreased immobility time and reduced aggressive behavior. However, genetic inactivation of the GSK-3α gene was associated with: decreased locomotion and impaired motor coordination, increased grooming activity, loss of social motivation and novelty; enhanced sensorimotor gating and impaired associated memory and coordination. GSK-3α KO mice exhibited a deficit in fear conditioning, however memory formation as assessed by a passive avoidance test was normal, suggesting that the animals are sensitized for active avoidance of a highly aversive stimulus in the fear-conditioning paradigm. Changes in cerebellar structure and function were observed in mutant mice along with a significant decrease of the number and size of Purkinje cells. Conclusion Taken together, these data support a role for the GSK-3α gene in CNS functioning and possible involvement in the development of psychiatric disorders.

Identification and genetic assay of a high-chlorophyll-content mutant in Rice

International Nuclear Information System (INIS)

Liu Baofu; Chen Xifeng; Jin Yang; Gu Zhimin; Ma Bojun; Zhu Xudong

2011-01-01

A deep rice mutant ZM1120 was screened from the γ-rays irradiation mutation library of Zhonghua 11. Compared to the wild-type control, this mutant were darker (greener) in shoots and leaves, and after sowing 60 and 90 d, the content of chlorophyll were increased by 16.0% and 7.2%, respectively, and the content of carotenoid also increased by 23.1% and 24.2%, respectively. After sowing 90 d the net photosynthetic rate and transpiration rate were increased by 16.3% and 11.4%, respectively. The agronomical traits of this mutant significantly changed, and the traits of plant height, flag-leaf length, flag-leaf width, tiller number per plant, panicle length and setting rate decreased, but the grain length and 1000-grain weight increased by 7.9% and 2.6%. Genetic analysis revealed that the mutation phenotype was controlled by a single recessive nuclear gene, and further cloning and function assay will be useful for understanding the mechanism of photosynthesis and for rice breeding in future. (authors)

Differential effects of lesion mimic mutants in barley on disease development by facultative pathogens

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McGrann, Graham R. D.; Steed, , Andrew; Burt, Christopher; Nicholson, Paul; Brown, James K. M.

2015-01-01

Lesion mimic mutants display spontaneous necrotic spots and chlorotic leaves as a result of mis-regulated cell death programmes. Typically these mutants have increased resistance to biotrophic pathogens but their response to facultative fungi that cause necrotrophic diseases is less well studied. The effect of altered cell death regulation on the development of disease caused by Ramularia collo-cygni, Fusarium culmorum and Oculimacula yallundae was explored using a collection of barley necrotic (nec) lesion mimic mutants. nec8 mutants displayed lower levels of all three diseases compared to nec9 mutants, which had increased R. collo-cygni but decreased F. culmorum disease symptoms. nec1 mutants reduced disease development caused by both R. collo-cygni and F. culmorum. The severity of the nec1-induced lesion mimic phenotype and F. culmorum symptom development was reduced by mutation of the negative cell death regulator MLO. The significant reduction in R. collo-cygni symptoms caused by nec1 was completely abolished in the presence of the mlo-5 allele and both symptoms and fungal biomass were greater than in the wild-type. These results indicate that physiological pathways involved in regulation of cell death interact with one another in their effects on different fungal pathogens. PMID:25873675

Dwarf mutant of rice variety Seratus Malam

International Nuclear Information System (INIS)

Mugiono, P. S.; Soemanggono, A.M.R.

1989-01-01

Full text: Seeds of 'Seratus Malam', a local tall upland variety with long panicles and high yield potential were irradiated with 10-50 krad gamma rays in 1983. From 50,000 M 2 plants, 130 semidwarf mutants and 1 dwarf mutant were selected. The dwarf mutant M-362 was obtained from the 10 krad treatment. The mutant shows about 50% reduction in plant height, but also in number of productive tillers. Thus the yield per plant is also significantly less. However, the mutant gene is not allelic to DGWG and therefore may be useful in cross breeding. (author)

ALS mutant SOD1 interacts with G3BP1 and affects stress granule dynamics.

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Gal, Jozsef; Kuang, Lisha; Barnett, Kelly R; Zhu, Brian Z; Shissler, Susannah C; Korotkov, Konstantin V; Hayward, Lawrence J; Kasarskis, Edward J; Zhu, Haining

2016-10-01

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Mutations in Cu/Zn superoxide dismutase (SOD1) are responsible for approximately 20 % of the familial ALS cases. ALS-causing SOD1 mutants display a gain-of-toxicity phenotype, but the nature of this toxicity is still not fully understood. The Ras GTPase-activating protein-binding protein G3BP1 plays a critical role in stress granule dynamics. Alterations in the dynamics of stress granules have been reported in several other forms of ALS unrelated to SOD1. To our surprise, the mutant G93A SOD1 transgenic mice exhibited pathological cytoplasmic inclusions that co-localized with G3BP1-positive granules in spinal cord motor neurons. The co-localization was also observed in fibroblast cells derived from familial ALS patient carrying SOD1 mutation L144F. Mutant SOD1, unlike wild-type SOD1, interacted with G3BP1 in an RNA-independent manner. Moreover, the interaction is specific for G3BP1 since mutant SOD1 showed little interaction with four other RNA-binding proteins implicated in ALS. The RNA-binding RRM domain of G3BP1 and two particular phenylalanine residues (F380 and F382) are critical for this interaction. Mutant SOD1 delayed the formation of G3BP1- and TIA1-positive stress granules in response to hyperosmolar shock and arsenite treatment in N2A cells. In summary, the aberrant mutant SOD1-G3BP1 interaction affects stress granule dynamics, suggesting a potential link between pathogenic SOD1 mutations and RNA metabolism alterations in ALS.

Isolation of L-methionine-enriched mutant of a methylotrophic yeast, Candida boidinii No.2201

International Nuclear Information System (INIS)

Tani, Y.; Lim, W.J.; Yang, H.C.

1988-01-01

Six strains of methylotrophic yeast were examined for production of L-methionine-enriched cells. Candida boidinii (kloeckera sp.) No. 2201,which accumulated 0.54 mg/g-dry cell weight (DCW) of free L-methionine (pool methionine), was selected as the parental strain for breeding L-methionine-rich mutants. Ethionine-resistant mutants were derived from the strain by UV irradiation. A mutant strain, E500-78,which was resistant to 500 μg/ml of DL-ethionine, accumulated 6.02 mg/g-DCW of pool methionine. The culture conditions for mutant strain E500-78 to increase pool methionine accumulation were optimized. As a result, the mutant strain accumulated 8.80 mg/g-DCW of pool methionine and contained 16.02 mg/g-DCW total methionine

Design of Trypanosoma rangeli sialidase mutants with improved trans-sialidase activity

DEFF Research Database (Denmark)

Nyffenegger, Christian; Nordvang, Rune Thorbjørn; Jers, Carsten

2017-01-01

were analyzed via kinetics for their ability to carry out trans-sialidase reaction using CGMP and D-lactose as substrates. The sialidase variants with 15 and 16 mutations, respectively, exhibited significantly improved trans-sialidase activity for D-lactose sialylation. Our results corroborate......, that computational studies of trans-glycosylation can be a valuable input in the design of novel trans-glycosidases, but also highlight the importance of experimental validation in order to assess the performance. In conclusion, two of the seven mutants displayed a dramatic switch in specificity from hydrolysis...

Mutant genes in pea breeding

International Nuclear Information System (INIS)

Swiecicki, W.K.

1990-01-01

Full text: Mutations of genes Dpo (dehiscing pods) and A (anthocyanin synthesis) played a role in pea domestication. A number of other genes were important in cultivar development for 3 types of usage (dry seeds, green vegetable types, fodder), e.g. fn, fna, le, p, v, fas and af. New genes (induced and spontaneous), are important for present ideotypes and are registered by the Pisum Genetics Association (PGA). Comparison of a pea variety ideotype with the variation available in gene banks shows that breeders need 'new' features. In mutation induction experiments, genotype, mutagen and method of treatment (e.g. combined or fractionated doses) are varied for broadening the mutation spectrum and selecting more genes of agronomic value. New genes are genetically analysed. In Poland, some mutant varieties with the gene afila were registered, controlling lodging by a shorter stem and a higher number of internodes. Really non-lodging pea varieties could strongly increase seed yield. But the probability of detecting a major gene for lodging resistance is low. Therefore, mutant genes with smaller influence on plant architecture are sought, to combine their effect by crossing. Promising seem to be the genes rogue, reductus and arthritic as well as a number of mutant genes not yet genetically identified. The gene det for terminal inflorescence - similarly to Vicia faba - changes plant development. Utilisation of assimilates and ripening should be better. Improvement of harvest index should give higher seed yield. A number of genes controlling disease resistance are well known (eg. Fw, Fnw, En, mo and sbm). Important in mass screening of resistance are closely linked gene markers. Pea gene banks collect respective lines, but mutants induced in highly productive cultivars would be better. Inducing gene markers sometimes seems to be easier than transfer by crossing. Mutation induction in pea breeding is probably more important because a high number of monogenic features are

EBV Positive Diffuse Large B Cell Lymphoma and Chronic Lymphocytic Leukemia Patients Exhibit Increased Anti-dUTPase Antibodies

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Marshall Williams

2018-05-01

Full Text Available The Epstein-Barr virus (EBV, which is a ubiquitous γ-herpesvirus, establishes a latent infection in more than 90% of the global adult population. EBV-associated malignancies have increased by 14.6% over the last 20 years, and account for approximately 1.5% of all cancers worldwide and 1.8% of all cancer deaths. However, the potential involvement/contribution of lytic proteins to the pathophysiology of EBV-associated cancers is not well understood. We have previously demonstrated that the EBV-deoxyuridine triphosphate nucleotidohydrolase (dUTPase modulates innate and adaptive immune responses by engaging the Toll-Like Receptor 2 (TLR2, which leads to the modulation of downstream genes involved in oncogenesis, chronic inflammation, and in effector T-cell function. Furthermore, examination of serum samples from diffuse large B-cell lymphoma (DLBCL and chronic lymphocytic leukemia patients revealed the presence of increased levels of anti-dUTPase antibodies in both cohorts compared to controls with the highest levels (3.67-fold increase observed in DLBCL female cases and the lowest (2.12-fold increase in DLBCL males. Using computer-generated algorithms, dUTPase amino acid sequence alignments, and functional studies of BLLF3 mutants, we identified a putative amino acid motif involved with TLR2 interaction. These findings suggest that the EBV-dUTPase: TLR2 interaction is a potential molecular target that could be used for developing novel therapeutics (small molecules/vaccines.

Deletion of Proton Gradient Regulation 5 (PGR5) and PGR5-Like 1 (PGRL1) proteins promote sustainable light-driven hydrogen production in Chlamydomonas reinhardtii due to increased PSII activity under sulfur deprivation.

Science.gov (United States)

Steinbeck, Janina; Nikolova, Denitsa; Weingarten, Robert; Johnson, Xenie; Richaud, Pierre; Peltier, Gilles; Hermann, Marita; Magneschi, Leonardo; Hippler, Michael

2015-01-01

Continuous hydrogen photo-production under sulfur deprivation was studied in the Chlamydomonas reinhardtii pgr5 pgrl1 double mutant and respective single mutants. Under medium light conditions, the pgr5 exhibited the highest performance and produced about eight times more hydrogen than the wild type, making pgr5 one of the most efficient hydrogen producer reported so far. The pgr5 pgrl1 double mutant showed an increased hydrogen burst at the beginning of sulfur deprivation under high light conditions, but in this case the overall amount of hydrogen produced by pgr5 pgrl1 as well as pgr5 was diminished due to photo-inhibition and increased degradation of PSI. In contrast, the pgrl1 was effective in hydrogen production in both high and low light. Blocking photosynthetic electron transfer by DCMU stopped hydrogen production almost completely in the mutant strains, indicating that the main pathway of electrons toward enhanced hydrogen production is via linear electron transport. Indeed, PSII remained more active and stable in the pgr mutant strains as compared to the wild type. Since transition to anaerobiosis was faster and could be maintained due to an increased oxygen consumption capacity, this likely preserves PSII from photo-oxidative damage in the pgr mutants. Hence, we conclude that increased hydrogen production under sulfur deprivation in the pgr5 and pgrl1 mutants is caused by an increased stability of PSII permitting sustainable light-driven hydrogen production in Chlamydomonas reinhardtii.

Mutant power: using mutant allele collections for yeast functional genomics.

Science.gov (United States)

Norman, Kaitlyn L; Kumar, Anuj

2016-03-01

The budding yeast has long served as a model eukaryote for the functional genomic analysis of highly conserved signaling pathways, cellular processes and mechanisms underlying human disease. The collection of reagents available for genomics in yeast is extensive, encompassing a growing diversity of mutant collections beyond gene deletion sets in the standard wild-type S288C genetic background. We review here three main types of mutant allele collections: transposon mutagen collections, essential gene collections and overexpression libraries. Each collection provides unique and identifiable alleles that can be utilized in genome-wide, high-throughput studies. These genomic reagents are particularly informative in identifying synthetic phenotypes and functions associated with essential genes, including those modeled most effectively in complex genetic backgrounds. Several examples of genomic studies in filamentous/pseudohyphal backgrounds are provided here to illustrate this point. Additionally, the limitations of each approach are examined. Collectively, these mutant allele collections in Saccharomyces cerevisiae and the related pathogenic yeast Candida albicans promise insights toward an advanced understanding of eukaryotic molecular and cellular biology. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

denV gene of bacteriophage T4 restores DNA excision repair to mei-9 and mus201 mutants of Drosophila melanogaster

International Nuclear Information System (INIS)

Banga, S.S.; Boyd, J.B.; Valerie, K.; Harris, P.V.; Kurz, E.M.; de Riel, J.K.

1989-01-01

The denV gene of bacteriophage T4 was fused to a Drosophila hsp70 (70-kDa heat shock protein) promoter and introduced into the germ line of Drosophila by P-element-mediated transformation. The protein product of that gene (endonuclease V) was detected in extracts of heat-shocked transformants with both enzymological and immunoblotting procedures. That protein restores both excision repair and UV resistance to mei-9 and mus201 mutants of this organism. These results reveal that the denV gene can compensate for excision-repair defects in two very different eukayotic mutants, in that the mus201 mutants are typical of excision-deficient mutants in other organisms, whereas the mei-9 mutants exhibit a broad pleiotropism that includes a strong meiotic deficiency. This study permits an extension of the molecular analysis of DNA repair to the germ line of higher eukaryotes. It also provides a model system for future investigations of other well-characterized microbial repair genes on DNA damage in the germ line of this metazoan organism

Respiration-dependent proton translocation in alkalophilic Bacillus firmus RAB and its non-alkalophilic mutant derivative.

Science.gov (United States)

Lewis, R J; Krulwich, T A; Reynafarje, B; Lehninger, A L

1983-02-25

Obligately alkalophilic Bacillus firmus RAB had a higher molar growth yield on L-malate (Ymal = 38 mg, dry weight/mmol of L-malate) than its non-alkalophilic mutant derivative, strain RABN (Ymal = 12 mg, dry weight/mmol of L-malate). Measurements of respiration dependent proton translocation by the two strains in the presence of K+ and valinomycin showed that the alkalophile also has much higher H+/O stoichiometries (at pH 9.0) than does the mutant (at pH 7.0). H+/O ratios for B. firmus RAB at pH 9.0 were as high as 13, with a frequently observed value of 9. These high values were observed in the first phase of a set of biphasic curves for both oxygen consumption and proton ejection. At pH 7.0, both the wild type and the mutant exhibited H+/O ratios near 4 in a single phase of oxygen consumption and proton ejection. The results are consistent with suggestions that the alkalophilic respiratory chain is especially well adapted for effective energy transduction at alkaline but not neutral pH.

Epilepsy, Behavioral Abnormalities, and Physiological Comorbidities in Syntaxin-Binding Protein 1 (STXBP1 Mutant Zebrafish.

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Brian P Grone

Full Text Available Mutations in the synaptic machinery gene syntaxin-binding protein 1, STXBP1 (also known as MUNC18-1, are linked to childhood epilepsies and other neurodevelopmental disorders. Zebrafish STXBP1 homologs (stxbp1a and stxbp1b have highly conserved sequence and are prominently expressed in the larval zebrafish brain. To understand the functions of stxbp1a and stxbp1b, we generated loss-of-function mutations using CRISPR/Cas9 gene editing and studied brain electrical activity, behavior, development, heart physiology, metabolism, and survival in larval zebrafish. Homozygous stxbp1a mutants exhibited a profound lack of movement, low electrical brain activity, low heart rate, decreased glucose and mitochondrial metabolism, and early fatality compared to controls. On the other hand, homozygous stxbp1b mutants had spontaneous electrographic seizures, and reduced locomotor activity response to a movement-inducing "dark-flash" visual stimulus, despite showing normal metabolism, heart rate, survival, and baseline locomotor activity. Our findings in these newly generated mutant lines of zebrafish suggest that zebrafish recapitulate clinical phenotypes associated with human syntaxin-binding protein 1 mutations.

Masking responses to light in period mutant mice.

Science.gov (United States)

Pendergast, Julie S; Yamazaki, Shin

2011-10-01

Masking is an acute effect of an external signal on an overt rhythm and is distinct from the process of entrainment. In the current study, we investigated the phase dependence and molecular mechanisms regulating masking effects of light pulses on spontaneous locomotor activity in mice. The circadian genes, Period1 (Per1) and Per2, are necessary components of the timekeeping machinery and entrainment by light appears to involve the induction of the expression of Per1 and Per2 mRNAs in the suprachiasmatic nuclei (SCN). We assessed the roles of the Per genes in regulating masking by assessing the effects of light pulses on nocturnal locomotor activity in C57BL/6J Per mutant mice. We found that Per1(-/-) and Per2(-/-) mice had robust negative masking responses to light. In addition, the locomotor activity of Per1(-/-)/Per2(-/-) mice appeared to be rhythmic in the light-dark (LD) cycle, and the phase of activity onset was advanced (but varied among individual mice) relative to lights off. This rhythm persisted for 1 to 2 days in constant darkness in some Per1(-/-)/Per2(-/-) mice. Furthermore, Per1(-/-)/Per2(-/-) mice exhibited robust negative masking responses to light. Negative masking was phase dependent in wild-type mice such that maximal suppression was induced by light pulses at zeitgeber time 14 (ZT14) and gradually weaker suppression occurred during light pulses at ZT16 and ZT18. By measuring the phase shifts induced by the masking protocol (light pulses were administered to mice maintained in the LD cycle), we found that the phase responsiveness of Per mutant mice was altered compared to wild-types. Together, our data suggest that negative masking responses to light are robust in Per mutant mice and that the Per1(-/-)/Per2(-/-) SCN may be a light-driven, weak/damping oscillator.

Absence of sodA Increases the Levels of Oxidation of Key Metabolic Determinants of Borrelia burgdorferi.

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Maria D Esteve-Gassent

Full Text Available Borrelia burgdorferi, the causative agent of Lyme disease, alters its gene expression in response to environmental signals unique to its tick vector or vertebrate hosts. B. burgdorferi carries one superoxide dismutase gene (sodA capable of controlling intracellular superoxide levels. Previously, sodA was shown to be essential for infection of B. burgdorferi in the C3H/HeN model of Lyme disease. We employed two-dimensional electrophoresis (2-DE and immunoblot analysis with antibodies specific to carbonylated proteins to identify targets that were differentially oxidized in the soluble fractions of the sodA mutant compared to its isogenic parental control strain following treatment with an endogenous superoxide generator, methyl viologen (MV, paraquat. HPLC-ESI-MS/MS analysis of oxidized proteins revealed that several proteins of the glycolytic pathway (BB0057, BB0020, BB0348 exhibited increased carbonylation in the sodA mutant treated with MV. Levels of ATP and NAD/NADH were reduced in the sodA mutant compared with the parental strain following treatment with MV and could be attributed to increased levels of oxidation of proteins of the glycolytic pathway. In addition, a chaperone, HtpG (BB0560, and outer surface protein A (OspA, BBA15 were also observed to be oxidized in the sodA mutant. Immunoblot analysis revealed reduced levels of Outer surface protein C (OspC, Decorin binding protein A (DbpA, fibronectin binding protein (BBK32, RpoS and BosR in the sodA mutant compared to the control strains. Viable sodA mutant spirochetes could not be recovered from both gp91/phox-⁄- and iNOS deficient mice while borrelial DNA was detected in multiple tissues samples from infected mice at significantly lower levels compared to the parental strain. Taken together, these observations indicate that the increased oxidation of select borrelial determinants and reduced levels of critical pathogenesis-associated lipoproteins contribute to the in vivo deficit of

Properties of adenyl cyclase and cyclic adenosine 3',5'-monophosphate receptor protein-deficient mutants of Escherichia coli

International Nuclear Information System (INIS)

Kumar, S.

1976-01-01

Several spontaneous cya and crp mutants of Escherichia coli have been selected as clones simultaneously resistant to phage lambda and nalidixic acid and characterized. Both cya and crp mutants have been found to grow as cocci with increased doubling times. They have increased resistance to some mutagens (methylmethanesulfonate, ultraviolet light, gamma rays), antibiotics (nalidixic acid, ampicillin), phages (lambda, T6), sublethal heat and hypotonic shock, and decreased resistance to neutral detergents (sodium dodecyl sulfate, sodium deoxycholate), a protein synthesis inhibitor (streptomycin), and a respiratory inhibitor (sodium azide). The nature of changes in cell parameters indicate fundamental alterations in the envelope structure of the cya and crp mutant cells. The new cya and crp mutants have been found to be multiply carbohydrate negative and nonmotile in conformity with similar previously isolated mutants. Studies of revertants and phi 80 cya + and phi 80 cya transductants indicated that the pleiotropic phenotype is related to a single mutational event at the cya or the crp locus in the mutants

Mutation induction of pleurotus ferulae by low-energy N+ ion implantation and characters of the selected mutant

International Nuclear Information System (INIS)

Chen Henglei; Wan Honggui; Zhang Jun; Zeng Xianxian

2008-01-01

In order to obtain Pleurotus ferulae with high temperature tolerance, mycelium mono-cells of wild type strain ACK was treated by nitrogen ion (5-30 keV, 1.5x10 15 -1.5x10 16 cm -2 ) implantation, and mutant CGMCC1762 was selected through auxotrophy screening method, which was Lys, VB6 auxotrophy stress with high temperature. We found that during riper period the surface layer mycelium of the mutant was not aging neither grew tegument even above 30 degree C. The mycelium endurable temperature of the mutant was increased 7 degree C compared with that of the wild type strain. The fruiting bodies growth temperature of the mutant was 16-20 degree C in daytime and was 6-12 degree C at night. The highest growth temperature of fruiting bodies of the mutant was increased by 5 degree C than that of original strain. Through three generation investigation, we found that the mutant CGMCC1762 was stable with high temperature tolerance. (authors)

Nutrient Changes and in Vitro Digestibility in Generative Stage of M10-BMR Sorghum Mutant Lines

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R. Sriagtula

2017-08-01

Full Text Available The objective of this research was to investigate the influences of generative stage on crude protein, crude fiber, ash, and crude fat contents as well as in-vitro dry matter and organic matter digestibilities of M-10 BMR sorghum mutant lines. This research was arranged into a randomized block design with 2 factors. The first factor was M-10 BMR sorghum mutant lines (Patir 3.1, Patir 3.2 and Patir 3.7 and the second factor was generative stages (flowering, soft dough and hard dough phase. The observed variables were proximate contents of stem, leaves and panicle of sorghum plant and in-vitro digestibility of whole plant. The results showed that leaves crude protein (CP was more influenced by M-10 BMR sorghum mutant lines. Stems and panicles CP were influenced by the interaction between M-10 BMR sorghum mutant lines and generative stages. Further generative stage reduced stems CP but increased panicles CP. Crude fiber (CF, ash, and ether extract (EE in leaves were not influenced by generative stages. Stems CF was influenced by M-10 BMR sorghum mutant lines and generative stages, while stems EE was more influenced by generative stages. Stems ash content was influenced by the interaction between M-10 BMR sorghum mutant lines and generative stages while panicles ash content was more influenced by generative stages. M-10 BMR sorghum mutant lines and hard dough phase increased in-vitro dry matter and organic matter digestibilities. Based on those findings, it can be concluded that the increased maturity reduces CP and CF contents so it increases in-vitro digestibilities.

Automated N-glycan profiling of a mutant Trypanosoma rangeli sialidase expressed in Pichia pastoris, using tandem mass spectrometry and bioinformatics

DEFF Research Database (Denmark)

Li, Haiying; Rasmussen, Morten I; Larsen, Martin R

2015-01-01

A mutant Trypanosoma rangeli sialidase, Tr7, expressed in Pichia pastoris, exhibits significant trans-sialidase activity, and has been used for analytical-scale production of sialylated human milk oligosaccharides. Mass spectrometry-based site-specific N-glycoprofiling of Tr7 showed that heteroge...

Characterization Of Laccase T-DNA Mutants In Arabidopsis thaliana

DEFF Research Database (Denmark)

Andersen, Jeppe Reitan; Asp, Torben; Mansfield, Shawn

2009-01-01

Laccases (P-diphenol:O2 oxidoreductase; EC 1.10.3.2), also termed laccase-like multicopper oxidases, are blue copper-containing oxidases which comprise multigene families in plants. In the Arabidopsis thaliana genome, 17 laccase genes (LAC1 to LAC17) have been annotated. To identify laccases...... for LAC15 T-DNA mutant seeds and an approximate 24 hour delay in germination was observed for these seeds. An approximate 20% reduction in glucose, galactose, and xylose was observed in primary stem cell walls of the LAC2 T-DNA mutants while similar relative increases in xylose were observed for LAC8...

Mutant in tobacco anther culture induced by 60Co γ-rays

International Nuclear Information System (INIS)

Tong Daoru; Jia Xinghua

1991-01-01

The tobacco anthers at uninucleate eccentric stage were irradiated by 60 Co γ-rays for the purpose of inducing desirable mutants. The results showed that the induction frequency of plantlets increased following 1kR of 60 Co γ-rays treatment. However, the time of plantlet induction was delayed and the percentage of responding anthers as well as the number of plantlets induced per anther significantly decreased after 3kR of 60 Co γ-ray radiation which was considered as a semilethal exposure. The plantlet numbers induced per anther were extremely low following 6kR of 60 Co γ-ray radiation. A white flower mutant appeared in the induced progenies. The tobacco leaf quality of this mutant were significantly improved as compared with its parental line. The mutant line has been tested and proved to have commercial value though the resistance to the black shank of tobacco slightly decreased as compared with the parental line

Allosteric Mutant IDH1 Inhibitors Reveal Mechanisms for IDH1 Mutant and Isoform Selectivity

Energy Technology Data Exchange (ETDEWEB)

Xie, Xiaoling; Baird, Daniel; Bowen, Kimberly; Capka, Vladimir; Chen, Jinyun; Chenail, Gregg; Cho, YoungShin; Dooley, Julia; Farsidjani, Ali; Fortin, Pascal; Kohls, Darcy; Kulathila, Raviraj; Lin, Fallon; McKay, Daniel; Rodrigues, Lindsey; Sage, David; Touré, B. Barry; van der Plas, Simon; Wright, Kirk; Xu, Ming; Yin, Hong; Levell, Julian; Pagliarini, Raymond A. (Novartis)

2017-03-01

Oncogenic IDH1 and IDH2 mutations contribute to cancer via production of R-2-hydroxyglutarate (2-HG). Here, we characterize two structurally distinct mutant- and isoform-selective IDH1 inhibitors that inhibit 2-HG production. Both bind to an allosteric pocket on IDH1, yet shape it differently, highlighting the plasticity of this site. Oncogenic IDH1R132H mutation destabilizes an IDH1 “regulatory segment,” which otherwise restricts compound access to the allosteric pocket. Regulatory segment destabilization in wild-type IDH1 promotes inhibitor binding, suggesting that destabilization is critical for mutant selectivity. We also report crystal structures of oncogenic IDH2 mutant isoforms, highlighting the fact that the analogous segment of IDH2 is not similarly destabilized. This intrinsic stability of IDH2 may contribute to observed inhibitor IDH1 isoform selectivity. Moreover, discrete residues in the IDH1 allosteric pocket that differ from IDH2 may also guide IDH1 isoform selectivity. These data provide a deeper understanding of how IDH1 inhibitors achieve mutant and isoform selectivity.

Semi-dwarf mutants for rice improvement

International Nuclear Information System (INIS)

Othman, Ramli; Osman, Mohammad; Ibrahim, Rusli

1990-01-01

Full text: MARDI and the National University of Malaysia embarked on a programme to induce resistance against blast in rice in 1978. MARDI also obtained semi dwarf mutants of cvs 'Mahsuri', 'Muda', 'Pongsu seribu' and 'Jarum Mas', which are under evaluation. The popular local rice variety 'Manik' was subjected to gamma irradiation (15-40 krad) and 101 promising semidwarf mutants have been obtained following selection in M 2 -M 6 . 29 of them show grain yields of 6.0-7.3 t/ha, compared with 5.7t for 'Manik'. Other valuable mutants were found showing long grain, less shattering, earlier maturity, and glutinous endosperm. One mutant, resistant to brown plant hopper yields 6.3t/ha. (author)

Regulatory Mechanisms of a Highly Pectinolytic Mutant of Penicillium occitanis and Functional Analysis of a Candidate Gene in the Plant Pathogen Fusarium oxysporum

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Gustavo Bravo-Ruiz

2017-09-01

Full Text Available Penicillium occitanis is a model system for enzymatic regulation. A mutant strain exhibiting constitutive overproduction of different pectinolytic enzymes both under inducing (pectin or repressing conditions (glucose was previously isolated after chemical mutagenesis. In order to identify the molecular basis of this regulatory mechanism, the genomes of the wild type and the derived mutant strain were sequenced and compared, providing the first reference genome for this species. We used a phylogenomic approach to compare P. occitanis with other pectinolytic fungi and to trace expansions of gene families involved in carbohydrate degradation. Genome comparison between wild type and mutant identified seven mutations associated with predicted proteins. The most likely candidate was a mutation in a highly conserved serine residue of a conserved fungal protein containing a GAL4-like Zn2Cys6 binuclear cluster DNA-binding domain and a fungus-specific transcription factor regulatory middle homology region. To functionally characterize the role of this candidate gene, the mutation was recapitulated in the predicted orthologue Fusarium oxysporum, a vascular wilt pathogen which secretes a wide array of plant cell wall degrading enzymes, including polygalacturonases, pectate lyases, xylanases and proteases, all of which contribute to infection. However, neither the null mutant nor a mutant carrying the analogous point mutation exhibited a deregulation of pectinolytic enzymes. The availability, annotation and phylogenomic analysis of the P. occitanis genome sequence represents an important resource for understanding the evolution and biology of this species, and sets the basis for the discovery of new genes of biotechnological interest for the degradation of complex polysaccharides.

Sequential super-stereotypy of an instinctive fixed action pattern in hyper-dopaminergic mutant mice: a model of obsessive compulsive disorder and Tourette's

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Houchard Kimberly R

2005-02-01

Full Text Available Abstract Background Excessive sequential stereotypy of behavioral patterns (sequential super-stereotypy in Tourette's syndrome and obsessive compulsive disorder (OCD is thought to involve dysfunction in nigrostriatal dopamine systems. In sequential super-stereotypy, patients become trapped in overly rigid sequential patterns of action, language, or thought. Some instinctive behavioral patterns of animals, such as the syntactic grooming chain pattern of rodents, have sufficiently complex and stereotyped serial structure to detect potential production of overly-rigid sequential patterns. A syntactic grooming chain is a fixed action pattern that serially links up to 25 grooming movements into 4 predictable phases that follow 1 syntactic rule. New mutant mouse models allow gene-based manipulation of brain function relevant to sequential patterns, but no current animal model of spontaneous OCD-like behaviors has so far been reported to exhibit sequential super-stereotypy in the sense of a whole complex serial pattern that becomes stronger and excessively rigid. Here we used a hyper-dopaminergic mutant mouse to examine whether an OCD-like behavioral sequence in animals shows sequential super-stereotypy. Knockdown mutation of the dopamine transporter gene (DAT causes extracellular dopamine levels in the neostriatum of these adult mutant mice to rise to 170% of wild-type control levels. Results We found that the serial pattern of this instinctive behavioral sequence becomes strengthened as an entire entity in hyper-dopaminergic mutants, and more resistant to interruption. Hyper-dopaminergic mutant mice have stronger and more rigid syntactic grooming chain patterns than wild-type control mice. Mutants showed sequential super-stereotypy in the sense of having more stereotyped and predictable syntactic grooming sequences, and were also more likely to resist disruption of the pattern en route, by returning after a disruption to complete the pattern from the

Development and characterization of mutant winter wheat (Triticum aestivum L.) accessions resistant to the herbicide quizalofop.

Science.gov (United States)

Ostlie, Michael; Haley, Scott D; Anderson, Victoria; Shaner, Dale; Manmathan, Harish; Beil, Craig; Westra, Phillip

2015-02-01

New herbicide resistance traits in wheat were produced through the use of induced mutagenesis. While herbicide-resistant crops have become common in many agricultural systems, wheat has seen few introductions of herbicide resistance traits. A population of Hatcher winter wheat treated with ethyl methanesulfonate was screened with quizalofop to identify herbicide-resistant plants. Initial testing identified plants that survived multiple quizalofop applications. A series of experiments were designed to characterize this trait. In greenhouse studies the mutants exhibited high levels of quizalofop resistance compared to non-mutant wheat. Sequencing ACC1 revealed a novel missense mutation causing an alanine to valine change at position 2004 (Alopecurus myosuroides reference sequence). Plants carrying single mutations in wheat's three genomes (A, B, D) were identified. Acetyl co-enzyme A carboxylase in resistant plants was 4- to 10-fold more tolerant to quizalofop. Populations of segregating backcross progenies were developed by crossing each of the three individual mutants with wild-type wheat. Experiments conducted with these populations confirmed largely normal segregation, with each mutant allele conferring an additive level of resistance. Further tests showed that the A genome mutation conferred the greatest resistance and the B genome mutation conferred the least resistance to quizalofop. The non-transgenic herbicide resistance trait identified will enhance weed control strategies in wheat.

Rescue of glaucoma-causing mutant myocilin thermal stability by chemical chaperones

Science.gov (United States)

Burns, J. Nicole; Orwig, Susan D.; Harris, Julia L.; Watkins, J. Derrick; Vollrath, Douglas; Lieberman, Raquel L.

2010-01-01

Mutations in myocilin cause an inherited form of open angle glaucoma, a prevalent neurodegenerative disorder associated with increased intraocular pressure. Myocilin forms part of the trabecular meshwork extracellular matrix presumed to regulate intraocular pressure. Missense mutations, clustered in the olfactomedin (OLF) domain of myocilin, render the protein prone to aggregation in the endoplasmic reticulum of trabecular meshwork cells, causing cell dysfunction and death. Cellular studies have demonstrated temperature-sensitive secretion of myocilin mutants, but difficulties in expression and purification have precluded biophysical characterization of wild-type (wt) myocilin and disease-causing mutants in vitro. We have overcome these limitations by purifying wt and select glaucoma-causing mutant (D380A, I477N, I477S, K423E) forms of the OLF domain (228–504) fused to maltose binding protein (MBP) from E. coli. Monomeric fusion proteins can be isolated in solution. To determine the relative stability of wt and mutant OLF domains, we developed a fluorescence thermal stability assay without removal of MBP, and provide the first direct evidence that mutated OLF is folded but less thermally stable than wt. We tested the ability of seven chemical chaperones to stabilize mutant myocilin. Only sarcosine and trimethylamine N-oxide were capable of shifting the melting temperature of all mutants tested to near that of wt OLF. Our work lays the foundation for the identification of tailored small molecules capable of stabilizing mutant myocilin and promoting secretion to the extracellular matrix, to better control intraocular pressure and ultimately delay the onset of myocilin glaucoma. PMID:20334347

MUTANT STRAIN of Bacillus subtilis IFBG MC-1 WITH INCREASED TRYPTOPHAN SYNTHESIS

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A. F. Tkachenko

2013-12-01

Full Text Available Scientific research of essential amino acids biotechnology is directed both to create optimum conditions for producer’s cultivation and economically viable raw materials selection for these technologies, so as breeding the more productive microorganisms strains capable of extracellular producing amino acids. For successful microbial synthesis it is necessary to have an excellent crop’s metabolism knowledge and ensure that the composition of growth medium have no repressing substances. Bacterial cultures from «Collection microorganism’s stains and plants line for food and agriculture biotechnology» from Institute of Food Biotechnology and Genomics of National Academy of Sciences of Ukraine have been studied. Tryptophan producer Bacillus subtilis have been selected, which accumulated the greatest amount of this amino acid in the cultivation liquid. The optimal culture producer conditions were selected. Using selection methods, namely mutagenesis with UV irradiation and sequential stepwise selection, mutant strain Bacillus subtilis IFBG MC-1 were obtained which produced nearly 50% more tryptophan (13.9 g/l than the parent strain.

ENU-mutagenesis mice with a non-synonymous mutation in Grin1 exhibit abnormal anxiety-like behaviors, impaired fear memory, and decreased acoustic startle response

Science.gov (United States)

2013-01-01

Background The Grin1 (glutamate receptor, ionotropic, NMDA1) gene expresses a subunit of N-methyl-D-aspartate (NMDA) receptors that is considered to play an important role in excitatory neurotransmission, synaptic plasticity, and brain development. Grin1 is a candidate susceptibility gene for neuropsychiatric disorders, including schizophrenia, bipolar disorder, and attention deficit/hyperactivity disorder (ADHD). In our previous study, we examined an N-ethyl-N-nitrosourea (ENU)-generated mutant mouse strain (Grin1Rgsc174/Grin1+) that has a non-synonymous mutation in Grin1. These mutant mice showed hyperactivity, increased novelty-seeking to objects, and abnormal social interactions. Therefore, Grin1Rgsc174/Grin1+ mice may serve as a potential animal model of neuropsychiatric disorders. However, other behavioral characteristics related to these disorders, such as working memory function and sensorimotor gating, have not been fully explored in these mutant mice. In this study, to further investigate the behavioral phenotypes of Grin1Rgsc174/Grin1+ mice, we subjected them to a comprehensive battery of behavioral tests. Results There was no significant difference in nociception between Grin1Rgsc174/Grin1+ and wild-type mice. The mutants did not display any abnormalities in the Porsolt forced swim and tail suspension tests. We confirmed the previous observations that the locomotor activity of these mutant mice increased in the open field and home cage activity tests. They displayed abnormal anxiety-like behaviors in the light/dark transition and the elevated plus maze tests. Both contextual and cued fear memory were severely deficient in the fear conditioning test. The mutant mice exhibited slightly impaired working memory in the eight-arm radial maze test. The startle amplitude was markedly decreased in Grin1Rgsc174/Grin1+ mice, whereas no significant differences between genotypes were detected in the prepulse inhibition (PPI) test. The mutant mice showed no obvious

Microbial production of squalene by a nicotinic acid-resistant mutant derived from Fusarium sp. No.5-128B

International Nuclear Information System (INIS)

Ogawa, T.; Kojima, I.; Takeda, N.; Fukuda, H.

1994-01-01

A nicotinic acid-resistant mutant, designated NA201, was obtained from Fusarium sp. no.5-128B by treatment with ultraviolet light. This mutant strain could grow in the presence of up to 500mM nicotinic acid in the culture medium, although the parent strain could not grow at concentrations of nicotinic acid above 200 mM. The Na201 strain exhibited morphological mutations, neither forming aerial hyphae nor secreting a red-brown pigment. However, it retained the resistance to kabicidin at 25 mg-l(-1) of the parent strain. The mutant NA201 cells contained high levels of squalene and low levels of ergosterol, about 53 times higher and five to six times lower, respectively, than those of the parent strain under standard culture conditions. The volumetric oxygen transfer coefficient (Kd) affected the level of squalene in the mutant cells. The Kd for the maximum production of squalene by the mutant was 24 mmol O2 l(-1)h(-1)atm(-1) and the level of squalene in the mutant cells was 26 mg (g cell)(-1) on a dry weight basis. The greatest accumulation of squalene by the Na201 strain, corresponding to 323 mg per liter of culture medium and 35 mg (g cell)(-1) on a dry weight basis, was achieved in a culture in which the Kd was changed from a high to a low value on the third day, with the simultaneous addition of 3% glucose (w/v)

Evaluation of tall rice mutant

International Nuclear Information System (INIS)

Hakim, L.; Azam, M.A.; Miah, A.J.; Mansur, M.A.; Akanda, H.R.

1989-01-01

One tall mutant (Mut NS1) of rice variety Nizersail was put to multilocation on-farm trial. It showed improvement over the parent in respect of by earlier maturity and higher grain yield at all locations and thus it appears as an improved mutant of Nizersail. (author). 6 refs

Isolation and characterization of radioresistant mutants in Bacillus subtilis and Bacillus thuringiensis

International Nuclear Information System (INIS)

Kalinin, V.L.; Petrov, V.N.; Petrova, T.M.

1981-01-01

Vegetative cells of Bac. thuringiensis var. galleriae (the wild-type strain 351) are much more sensitive to lethal effects of UV light and 60 Co-γ-rays than those of Bac. subtilis (the wild-type strain 168). This difference is less pronounced for spores of these strains. By means of repeated γ-irradiation-regrowth cycles radioresistant mutants Bac. thuringiensis Gamsup(r) 14 and Bac. subtilis Gamsup(r) 9 were selected. The vegetative cells of these mutants are correspondingly 19 times and 3.9 times more resistant to lethal effects of γ-radiation than the cells of the parental strains. The resistance of the Gamsup(r) mutant cells to lethal effects of UV light and H 2 O 2 is also increased. The spores of the Gamsup(r) 14 mutant are 1.5-1.7 times more resistant to γ-radiation and UV light than the wild-type spores. The radioresistant mutants and the parental strains do not vary in their capacity for host-cell reactivation of UV- or γ-irradiated phages Tg13 and 105

Homologous series of induced early mutants in indican rice. Pt.1. The production of homologous series of early mutants

International Nuclear Information System (INIS)

Chen Xiulan; Yang Hefeng; He Zhentian; Han Yuepeng; Liu Xueyu

1999-01-01

The percentage of homologous series of early mutants induced from the same Indican rice variety were almost the same (1.37%∼1.64%) in 1983∼1993, but the ones from the different eco-typical varieties were different. The early variety was 0.73%, the mid variety was 1.51%, and the late variety was 1.97%. The percentage of homologous series of early mutants from the varieties with the same pedigree and relationship were similar, but the one from the cog nation were lower than those from distant varieties. There are basic laws and characters in the homologous series of early mutants: 1. The inhibited phenotype is the basic of the homologous series of early mutants; 2. The production of the homologous series of early mutants is closely related with the growing period of the parent; 3. The parallel mutation of the stem and leaves are simultaneously happened with the variation of early or late maturing; 4. The occurrence of the homologous series of early mutants is in a state of imbalance. According to the law of parallel variability, the production of homologous series of early mutants can be predicted as long as the parents' classification of plant, pedigree and ecological type are identified. Therefore, the early breeding can be guided by the law of homologous series of early mutants

Susceptibility of glucokinase-MODY mutants to inactivation by oxidative stress in pancreatic β-cells.

Science.gov (United States)

Cullen, Kirsty S; Matschinsky, Franz M; Agius, Loranne; Arden, Catherine

2011-12-01

The posttranslational regulation of glucokinase (GK) differs in hepatocytes and pancreatic β-cells. We tested the hypothesis that GK mutants that cause maturity-onset diabetes of the young (GK-MODY) show compromised activity and posttranslational regulation in β-cells. Activity and protein expression of GK-MODY and persistent hyperinsulinemic hypoglycemia of infancy (PHHI) mutants were studied in β-cell (MIN6) and non-β-cell (H4IIE) models. Binding of GK to phosphofructo-2-kinase, fructose-2,6-bisphosphatase (PFK2/FBPase2) was studied by bimolecular fluorescence complementation in cell-based models. Nine of 11 GK-MODY mutants that have minimal effect on enzyme kinetics in vitro showed decreased specific activity relative to wild type when expressed in β-cells. A subset of these were stable in non-β-cells but showed increased inactivation in conditions of oxidative stress and partial reversal of inactivation by dithiothreitol. Unlike the GK-MODY mutants, four of five GK-PHHI mutants had similar specific activity to wild type and Y214C had higher activity than wild type. The GK-binding protein PFK2/FBPase2 protected wild-type GK from oxidative inactivation and the decreased stability of GK-MODY mutants correlated with decreased interaction with PFK2/FBPase2. Several GK-MODY mutants show posttranslational defects in β-cells characterized by increased susceptibility to oxidative stress and/or protein instability. Regulation of GK activity through modulation of thiol status may be a physiological regulatory mechanism for the control of GK activity in β-cells.

Deregulation of the Arginine Deiminase (arc) Operon in Penicillin-Tolerant Mutants of Streptococcus gordonii

OpenAIRE

Caldelari, I.; Loeliger, B.; Langen, H.; Glauser, M. P.; Moreillon, P.

2000-01-01

Penicillin tolerance is an incompletely understood phenomenon that allows bacteria to resist drug-induced killing. Tolerance was studied with independent Streptococcus gordonii mutants generated by cyclic exposure to 500 times the MIC of penicillin. Parent cultures lost 4 to 5 log10 CFU/ml of viable counts/24 h. In contrast, each of four independent mutant cultures lost ≤2 log10 CFU/ml/24 h. The mutants had unchanged penicillin-binding proteins but contained increased amounts of two proteins ...

Mathematical modeling of mutant transferrin-CRM107 molecular conjugates for cancer therapy.

Science.gov (United States)

Yoon, Dennis J; Chen, Kevin Y; Lopes, André M; Pan, April A; Shiloach, Joseph; Mason, Anne B; Kamei, Daniel T

2017-03-07

The transferrin (Tf) trafficking pathway is a promising mechanism for use in targeted cancer therapy due to the overexpression of transferrin receptors (TfRs) on cancerous cells. We have previously developed a mathematical model of the Tf/TfR trafficking pathway to improve the efficiency of Tf as a drug carrier. By using diphtheria toxin (DT) as a model toxin, we found that mutating the Tf protein to change its iron release rate improves cellular association and efficacy of the drug. Though this is an improvement upon using wild-type Tf as the targeting ligand, conjugated toxins like DT are unfortunately still highly cytotoxic at off-target sites. In this work, we address this hurdle in cancer research by developing a mathematical model to predict the efficacy and selectivity of Tf conjugates that use an alternative toxin. For this purpose, we have chosen to study a mutant of DT, cross-reacting material 107 (CRM107). First, we developed a mathematical model of the Tf-DT trafficking pathway by extending our Tf/TfR model to include intracellular trafficking via DT and DT receptors. Using this mathematical model, we subsequently investigated the efficacy of several conjugates in cancer cells: DT and CRM107 conjugated to wild-type Tf, as well as to our engineered mutant Tf proteins (K206E/R632A Tf and K206E/R534A Tf). We also investigated the selectivity of mutant Tf-CRM107 against non-neoplastic cells. Through the use of our mathematical model, we predicted that (i) mutant Tf-CRM107 exhibits a greater cytotoxicity than wild-type Tf-CRM107 against cancerous cells, (ii) this improvement was more drastic with CRM107 conjugates than with DT conjugates, and (iii) mutant Tf-CRM107 conjugates were selective against non-neoplastic cells. These predictions were validated with in vitro cytotoxicity experiments, demonstrating that mutant Tf-CRM107 conjugates is indeed a more suitable therapeutic agent. Validation from in vitro experiments also confirmed that such whole

Staphylococcus aureus β-Toxin Mutants Are Defective in Biofilm Ligase and Sphingomyelinase Activity, and Causation of Infective Endocarditis and Sepsis.

Science.gov (United States)

Herrera, Alfa; Vu, Bao G; Stach, Christopher S; Merriman, Joseph A; Horswill, Alexander R; Salgado-Pabón, Wilmara; Schlievert, Patrick M

2016-05-03

β-Toxin is an important virulence factor of Staphylococcus aureus, contributing to colonization and development of disease [Salgado-Pabon, W., et al. (2014) J. Infect. Dis. 210, 784-792; Huseby, M. J., et al. (2010) Proc. Natl. Acad. Sci. U.S.A. 107, 14407-14412; Katayama, Y., et al. (2013) J. Bacteriol. 195, 1194-1203]. This cytotoxin has two distinct mechanisms of action: sphingomyelinase activity and DNA biofilm ligase activity. However, the distinct mechanism that is most important for its role in infective endocarditis is unknown. We characterized the active site of β-toxin DNA biofilm ligase activity by examining deficiencies in site-directed mutants through in vitro DNA precipitation and biofilm formation assays. Possible conformational changes in mutant structure compared to that of wild-type toxin were assessed preliminarily by trypsin digestion analysis, retention of sphingomyelinase activity, and predicted structures based on the native toxin structure. We addressed the contribution of each mechanism of action to producing infective endocarditis and sepsis in vivo in a rabbit model. The H289N β-toxin mutant, lacking sphingomyelinase activity, exhibited lower sepsis lethality and infective endocarditis vegetation formation compared to those of the wild-type toxin. β-Toxin mutants with disrupted biofilm ligase activity did not exhibit decreased sepsis lethality but were deficient in infective endocarditis vegetation formation compared to the wild-type protein. Our study begins to characterize the DNA biofilm ligase active site of β-toxin and suggests β-toxin functions importantly in infective endocarditis through both of its mechanisms of action.

Studies on reduced height mutants in rice

International Nuclear Information System (INIS)

Narahari, P.; Bhagwat, S.G.

1984-01-01

Two cross-bred derivatives of the mutant TR5xTR17 and TR21 continued to show promise and were advanced to wider scale testing. TR5 was found to carry a semi-dwarfing gene different from that in IR8. New semi-dwarf mutants were screened from M 2 through M 4 from two separate radiation experiments. The gibberellin response of seedlings of mutant and tester strains was evaluated and crosses of tester stocks and mutant semi-dwarfs were made for genetic analyses. (author)

Genetic analysis and molecular detection of the corn endosperm mutants induced by space flight

International Nuclear Information System (INIS)

Zhang Caibo; Zhou Yuanyuan; Wang Hanyu; Wang Hongwei; Wang Shengqing; Rong Tingzhao; Cao Moju

2013-01-01

In this study, two maize inbred lines 08-641 and 18-599 were carried into cosmic space by recoverable satellite 'Shijian 8', grain shrunken transparently and opaquely mutants were selected as experimental materials and their soluble sugar content in kernel were measured by annthrone colorimetry. The content of soluble sugar in mutant st1 kernels began to rise in 10 days after pollination, to reach the peak in 25 days and significantly higher than the contrast 08-641, while in mutant sol kernels it began to rise in 10 days after pollination, to reach the peak in 20 days and significantly higher than the contrast 18-599. The results of genetic analysis and allelism test showed that the trait in both mutants was all controlled by a single recessive gene, the mutant st1 was allelic to the su1 and the mutant sol was allelic to the sh2. DNA sequence alignment found 2 single-base mutations in 2 and 13 exon of su1 gene in the mutant st1 and 3 single-base mutations in 2, 5 and 16 exon of sh2 gene in mutant so1 leading to the change in amino acid sequences. So it is inferred that starch biosynthesis in the mutants may be blocked by these mutations, which lead to the increase of soluble sugar content in kernel. (authors)

Results of the use of induced mutants in maize breeding

International Nuclear Information System (INIS)

Balint, A.; Kovacs, Gezane; Hajos, Laszlone; Geczki, I.

1979-01-01

The investigated mutagens have the same effect on the increasing of protein content. In the case of WF9 mutants no essential improvement can be found compared with the untreated co trol selected for protein. ''Lines'' flowering 16-19 days earlier than controls were produced; the most effective agent of this production is the fast neutron. Mutation caused a significant change in their combining ability, but there were more negative variants than positive ones. Three hybrids with stronger stalk than that of MvSc 620 were obtained. Stalk standing ability of mutants did not improve. The flowering date of lines (male) is in r=+0.5672 +++ correlation to the yield of their test hybrid. Mutant lines in SC test cross seemed to be stable. The correlation of the yield of two years is r=+0.8659. The correlation of both the yield of test hybrids to the protein content of mutant lines (r=0.2307) and the flowering date of lines to their protein content (r=-0.3032) is loose. The earliest mutant line of WF9, which produced low crop (5000 kg/ha) when crossed with N6, gave a high-yielding hybrid when crossed with other lines. The average yield of eight combinations was 10050 kg/ha and the highest yield was 11680 kg/ha. (author)

Microevolution of Candida albicans in macrophages restores filamentation in a nonfilamentous mutant.

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Anja Wartenberg

2014-12-01

Full Text Available Following antifungal treatment, Candida albicans, and other human pathogenic fungi can undergo microevolution, which leads to the emergence of drug resistance. However, the capacity for microevolutionary adaptation of fungi goes beyond the development of resistance against antifungals. Here we used an experimental microevolution approach to show that one of the central pathogenicity mechanisms of C. albicans, the yeast-to-hyphae transition, can be subject to experimental evolution. The C. albicans cph1Δ/efg1Δ mutant is nonfilamentous, as central signaling pathways linking environmental cues to hyphal formation are disrupted. We subjected this mutant to constant selection pressure in the hostile environment of the macrophage phagosome. In a comparatively short time-frame, the mutant evolved the ability to escape macrophages by filamentation. In addition, the evolved mutant exhibited hyper-virulence in a murine infection model and an altered cell wall composition compared to the cph1Δ/efg1Δ strain. Moreover, the transcriptional regulation of hyphae-associated, and other pathogenicity-related genes became re-responsive to environmental cues in the evolved strain. We went on to identify the causative missense mutation via whole genome- and transcriptome-sequencing: a single nucleotide exchange took place within SSN3 that encodes a component of the Cdk8 module of the Mediator complex, which links transcription factors with the general transcription machinery. This mutation was responsible for the reconnection of the hyphal growth program with environmental signals in the evolved strain and was sufficient to bypass Efg1/Cph1-dependent filamentation. These data demonstrate that even central transcriptional networks can be remodeled very quickly under appropriate selection pressure.

Genetic requirements for high constitutive SOS expression in recA730 mutants of Escherichia coli.

Science.gov (United States)

Vlašić, Ignacija; Šimatović, Ana; Brčić-Kostić, Krunoslav

2011-09-01

The RecA protein in its functional state is in complex with single-stranded DNA, i.e., in the form of a RecA filament. In SOS induction, the RecA filament functions as a coprotease, enabling the autodigestion of the LexA repressor. The RecA filament can be formed by different mechanisms, but all of them require three enzymatic activities essential for the processing of DNA double-stranded ends. These are helicase, 5'-3' exonuclease, and RecA loading onto single-stranded DNA (ssDNA). In some mutants, the SOS response can be expressed constitutively during the process of normal DNA metabolism. The RecA730 mutant protein is able to form the RecA filament without the help of RecBCD and RecFOR mediators since it better competes with the single-strand binding (SSB) protein for ssDNA. As a consequence, the recA730 mutants show high constitutive SOS expression. In the study described in this paper, we studied the genetic requirements for constitutive SOS expression in recA730 mutants. Using a β-galactosidase assay, we showed that the constitutive SOS response in recA730 mutants exhibits different requirements in different backgrounds. In a wild-type background, the constitutive SOS response is partially dependent on RecBCD function. In a recB1080 background (the recB1080 mutation retains only helicase), constitutive SOS expression is partially dependent on RecBCD helicase function and is strongly dependent on RecJ nuclease. Finally, in a recB-null background, the constitutive SOS expression of the recA730 mutant is dependent on the RecJ nuclease. Our results emphasize the importance of the 5'-3' exonuclease for high constitutive SOS expression in recA730 mutants and show that RecBCD function can further enhance the excellent intrinsic abilities of the RecA730 protein in vivo. Copyright © 2011, American Society for Microbiology. All Rights Reserved.

A recombinant hypoallergenic parvalbumin mutant for immunotherapy of IgE-mediated fish allergy.

Science.gov (United States)

Swoboda, Ines; Bugajska-Schretter, Agnes; Linhart, Birgit; Verdino, Petra; Keller, Walter; Schulmeister, Ulrike; Sperr, Wolfgang R; Valent, Peter; Peltre, Gabriel; Quirce, Santiago; Douladiris, Nikolaos; Papadopoulos, Nikolaos G; Valenta, Rudolf; Spitzauer, Susanne

2007-05-15

IgE-mediated allergy to fish is a frequent cause of severe anaphylactic reactions. Parvalbumin, a small calcium-binding protein, is the major fish allergen. We have recently isolated a cDNA coding for carp parvalbumin, Cyp c 1, and expressed in Escherichia coli a recombinant Cyp c 1 molecule, which contained most IgE epitopes of saltwater and freshwater fish. In this study, we introduced mutations into the calcium-binding domains of carp parvalbumin by site-directed mutagenesis and produced in E. coli three parvalbumin mutants containing amino acid exchanges either in one (single mutants; Mut-CD and Mut-EF) or in both of the calcium-binding sites (double mutant; Mut-CD/EF). Circular dichroism analyses of the purified derivatives and the wild-type allergen showed that Mut-CD/EF exhibited the greatest reduction of overall protein fold. Dot blot assays and immunoblot inhibition experiments performed with sera from 21 fish-allergic patients showed that Mut-CD/EF had a 95% reduced IgE reactivity and represented the derivative with the least allergenic activity. The latter was confirmed by in vitro basophil histamine release assays and in vivo skin prick testing. The potential applicability for immunotherapy of Mut-CD/EF was demonstrated by the fact that mouse IgG Abs could be raised by immunization with the mutated molecule, which cross-reacted with parvalbumins from various fish species and inhibited the binding of fish-allergic patients' IgE to the wild-type allergen. Using the hypoallergenic carp parvalbumin mutant Mut-CD/EF, it may be possible to treat fish allergy by immunotherapy.

Arg156 in the AP2-domain exhibits the highest binding activity among the 20 individuals to the GCC box in BnaERF-B3-hy15, a mutant ERF transcription factor from Brassica napus

Directory of Open Access Journals (Sweden)

Jing Zhuang

2016-10-01

Full Text Available To develop mutants of the ERF factor with more binding activities to the GCC box, we performed in vitro directed evolution by using DNA shuffling and screened mutants through yeast one-hybrid assay. Here, a series of mutants were obtained and used to reveal key amino acids that induce changes in the DNA binding activity of the BnaERF-B3 protein. With the BnaERF-B3-hy15 as the template, we produced 12 mutants which host individual mutation of potential key residues. We found that amino acid 156 is the key site, and the other 18 mutants host the 18 corresponding individual amino acid residues at site 156. Among the 20 individuals comprising WT (Gly156, Mu3 (Arg156, and 18 mutants with other 18 amino acid residues, Arg156 in the AP2-domain is the amino acid residue with the highest binding activity to the GCC box. The structure of the α-helix in the AP2-domain affects the binding activity. Other residues within AP2-domain modulated binding activity of ERF protein, suggesting that these positions are important for binding activity. Comparison of the mutant and wild-type transcription factors revealed the relationship of protein function and sequence modification. Our result provides a potential useful resource for understanding the trans-activation of ERF proteins.

A transcriptionally active estrogen receptor mutant is a novel type of dominant negative inhibitor of estrogen action.

Science.gov (United States)

McInerney, E M; Ince, B A; Shapiro, D J; Katzenellenbogen, B S

1996-12-01

We have characterized a human estrogen receptor (ER) mutant, V364E, which has a single amino acid substitution in its hormone-binding domain. This ER mutant is fully active or even superactive at saturating levels of estradiol (10(-8) M E2) yet has the capacity to act as a strong dominant negative inhibitor of the wild type ER. In transient transfection assays using ER-negative Chinese hamster ovary (CHO) cells and two different estrogen response element (ERE)-containing promoter reporter genes, V364E treated with 10(-8) M E2 exhibited approximately 250% and 100% of the activity of the wild type ER with these two promoter contexts, respectively. Despite the high activity of V364E when present alone in cells, coexpression of both V364E and wild type ER causes a significant decrease in overall ER-mediated transcriptional activity. On the TATA promoter, where V364E was more inhibitory, estrogen-stimulated activity was reduced by approximately 50% at a 1:1 ratio of mutant to wild type ER expression vector, and at a 10:1 ratio, 75% of ER activity was inhibited. V364E was expressed at lower levels than wild type ER and has a approximately 40-fold lower affinity for E2 compared with wild type ER. In promoter interference assays, V364E exhibited a strict dependence upon E2 for binding to an ERE. Surprisingly, even when V364E was unable to bind to ERE DNA (i.e. either at low E2 concentration or by mutation of its DNA-binding domain), this mutant retained full dominant negative activity. This highly active ER mutant is, thus, able to repress ER-mediated transcription when the mutant and wild type ER are present together in cells, even without DNA binding. Since competition for ERE binding and the formation of inactive heterodimers cannot fully account for the dominant negative activity of V364E, it is probable that altered interactions with proteins important in ER-mediated transcription play a key role in the repression of transcription by V364E. The properties and probable

Perturbation of formate pathway for hydrogen production by expressions of formate hydrogen lyase and its transcriptional activator in wild Enterobacter aerogenes and its mutants

Energy Technology Data Exchange (ETDEWEB)

Lu, Yuan; Zhao, Hongxin; Zhang, Chong; Lai, Qiheng; Xing, Xin-Hui [Institute of Biochemical Engineering, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2009-06-15

To examine perturbation effects of formate pathway on hydrogen productivity in Enterobacter aerogenes (Ea), formate dehydrogenase FDH-H gene (fdhF) and formate hydrogen lyase activator protein FHLA gene (fhlA) originated from Escherichia coli, were overexpressed in the wild strain Ea, its hycA-deleted mutant (A) by knockout the formate hydrogen lyase repressor and hybO-deleted mutant (O) by knockout of the uptake hydrogenase, respectively. Overexpression of fdhF and fhlA promoted cell growth and volumetric hydrogen production rates of all the strains, and the hydrogen production per gram cell dry weight (CDW) for Ea, A and O was increased by 38.5%, 21.8% and 5.25%, respectively. The fdhF and fhlA overexpression improved the hydrogen yield per mol glucose of strains Ea and A, but declined that of strain O. The increase of hydrogen yield of the strain Ea with fdhF and fhlA expression was mainly attributed to the increase of formate pathway, while for the mutant A, the improved hydrogen yield with fdhF and fhlA expression was mainly due to the increase of NADH pathway. Analysis of the metabolites and ratio of ethanol-to-acetate showed that the cellular redox state balance and energy level were also changed for these strains by fdhF and fhlA expression. These findings demonstrated that the hydrogen production was not only dependent on the hydrogenase genes, but was also affected by the regulation of the whole metabolism. Therefore, fdhF and fhlA expression in different strains of E. aerogenes could exhibit different perturbation effects on the metabolism and the hydrogen productivity. (author)

A UV-resistant mutant without an increased repair synthesis activity, established from a UV-sensitive human clonal cell line

International Nuclear Information System (INIS)

Suzuki, N.

1984-01-01

When cells of a human clonal cell line, RSa, with high sensitivity to UV lethality, were treated with the mutagen, ethyl methanesulfonate, a variant cell strain, UVr-1, was established as a mutant resistant to 254-nm far-ultraviolet radiation (UV). Cell proliferation studies showed that UVr-1 cells survived and actively proliferated at doses of UV-irradiation that greatly suppressed the proliferation of RSa cells. Colony-formation assays also confirmed the increased resistance of UVr-1 cells to UV. The recovery from a UV-induced inhibition in DNA synthesis, as [methyl- 3 H]thymidine uptake into cellular DNA, was more pronounced in UVr-1 cells than in RSa cells. Nevertheless, there was no significant difference in the activity of UV-induced DNA repair synthesis in either cell line, as estimated by the extent of unscheduled DNA synthesis and DNA repair replication. These characteristics of UVr-1 cells are discussed in the light of a previously reported UV-resistant variant, UVr-10, which had an increased DNA repair synthesis activity. (Auth.)

Evaluation of artemisia mutant lines conducted from gamma irradiation treatment

International Nuclear Information System (INIS)

Ragapadmi Purnamaningsih; EG Lestari; M Syukur

2010-01-01

Cases of Malaria diseases attack in Indonesia has been increasing. Plasmodium falciparum the cause of malaria disease is now resistant to the usual medicine. One of malaria medicine which recommended by WHO is artemisinine compound extracted from Artemisia annua L plant. Low artemisinine content is one problem of Artemisia development in Indonesia. Increasing genetic variation using gamma irradiation is one alternative method to improve artemisinin content. In 2007, induce mutation had been done to artemisia seeds using gamma irradiation at dosage of 10-100 Gy. The good rooting planlet was regenerated and acclimatized in the green house, and then the seedling (M0 generation) was planted in the field at 1545 m asl. Plants derived from seeds without gamma irradiation treatment and cultured in vitro (in vitro control) were used as control. The result showed there were some morphological variations between the mutant lines (plant height, shape of the leaves and time of flowering). Ten mutant lines were selected based on biomass yield and analyzed for the artemisinine content.The result showed that artemisinine content of the mutant lines ranged from 0.44 - 1.41%, and it was significantly higher than that of in vitro control (0.43%). (author)

Vasopressin increases S261 phosphorylation in AQP2-P262L, a mutant in recessive nephrogenic diabetes insipidus

NARCIS (Netherlands)

Trimpert, C.; van den Berg, D.T.; Fenton, R.A.; Klussmann, E.; Deen, P.M.T.

2012-01-01

Background Mutations in the aquaporin-2 (AQP2) gene cause nephrogenic diabetes insipidus (NDI), a renal disorder characterized by polyuria due to a lacking antidiuretic response to vasopressin. While most AQP2 mutants in recessive NDI are misfolded and retained in the endoplasmic reticulum,

Sensitive in situ monitoring of a recombinant bioluminescent Yersinia enterocolitica reporter mutant in real time on Camembert cheese.

Science.gov (United States)

Maoz, Ariel; Mayr, Ralf; Bresolin, Geraldine; Neuhaus, Klaus; Francis, Kevin P; Scherer, Siegfried

2002-11-01

Bioluminescent mutants of Yersinia enterocolitica were generated by transposon mutagenesis using a promoterless, complete lux operon (luxCDABE) derived from Photorhabdus luminescens, and their production of light in the cheese environment was monitored. Mutant B94, which had the lux cassette inserted into an open reading frame of unknown function was used for direct monitoring of Y. enterocolitica cells on cheeses stored at 10 degrees C by quantifying bioluminescence using a photon-counting, intensified charge-coupled device camera. The detection limit on cheese was 200 CFU/cm(2). Bioluminescence of the reporter mutant was significantly regulated by its environment (NaCl, temperature, and cheese), as well as by growth phase, via the promoter the lux operon had acquired upon transposition. At low temperatures, mutant B94 did not exhibit the often-reported decrease of photon emission in older cells. It was not necessary to include either antibiotics or aldehyde in the food matrix in order to gain quantitative, reproducible bioluminescence data. As far as we know, this is the first time a pathogen has been monitored in situ, in real time, in a "real-product" status, and at a low temperature.

Characterization of Novel Sorghum brown midrib Mutants from an EMS-Mutagenized Population

OpenAIRE

Sattler, Scott E.; Saballos, Ana; Xin, Zhanguo; Funnell-Harris, Deanna L.; Vermerris, Wilfred; Pedersen, Jeffrey F.

2014-01-01

Reducing lignin concentration in lignocellulosic biomass can increase forage digestibility for ruminant livestock and saccharification yields of biomass for bioenergy. In sorghum (Sorghum bicolor (L.) Moench) and several other C4 grasses, brown midrib (bmr) mutants have been shown to reduce lignin concentration. Putative bmr mutants isolated from an EMS-mutagenized population were characterized and classified based on their leaf midrib phenotype and allelism tests with the previously describe...

Genetic analysis of DNA repair in Aspergillus: evidence for different types of MMS-sensitive hyperrec mutants.

Science.gov (United States)

Käfer, E; Mayor, O

1986-07-01

To identify genes which affect DNA repair and possibly recombination in Aspergillus nidulans, mutants hypersensitive to methyl methanesulphonate (MMS) were induced with ultraviolet light (UV) or gamma-rays. About half of them contained associated translocations and many were hypersensitive to UV and/or defective in meiosis. Two are alleles of the known uvsB gene while most others define new genes. In addition, among available uvs mutants many were found to be MMS-sensitive. Some of the various uncharacterized ones were identified as alleles of known uvs, but 5 of them were mapped in 2 new genes, uvsH and uvsJ. To identify functional and epistatic groups, mutants from each uvs gene were tested for effects on recombination and mutation, and double mutant uvs strains were compared for UV survival to their component single mutant strains. 3 epistatic pairs were identified, (1) uvsF and H, (2) uvsB and D, and (3) uvsC and E. Conclusive interpair tests were difficult, because such double mutant combinations were frequently lethal or nearly so. The first pair, uvsF and H, shared some of the properties of excision-defective mutants, both uvs being very highly sensitive to UV for mutation as well as survival. But unlike such mutants, uvsH was also sensitive to gamma-rays and defective in meiosis. Both uvs showed normal levels of meiotic recombination, but greatly increased spontaneous mitotic crossing-over, being the most "hyperrec" types among all uvs. The second pair, uvsB and uvsC, which was similarly hyperrec showed only slight increases of UV-induced mutation (less than 2-fold). As a main effect, these uvs caused very high frequencies of unbalanced, unstable segregants from diploid conidia (30 X), but few of these were recognizable aneuploids. The third pair, uvsC and E, which are known to be rec- for gene conversion, caused reduced mitotic crossing-over in diploids and increased levels of haploid segregants. These mutants are spontaneous mutators, but showed less UV

Molecular analysis of waxy mutants in rice

International Nuclear Information System (INIS)

Yatou, O.; Amano, E.

1990-01-01

Full text: The 'waxy' gene is a structural gene coding a glycosyl transferase which synthesises amylose in the endosperm tissue. 'Non-waxy' rice cultivars have an active gene and their amylose content is 18-25% depending upon gene performance and modifier genes. In 'waxy' rice, no amylose is found because the enzyme is absent. In mutants induced by gamma rays, neutrons, EI or EMS, amylose content ranged from 0 to 20%, i.e. there are intermediate phenotypes as well. Some of them had the same amount of the enzyme as a 'non-waxy' cultivar, even fully 'waxy' mutants showed a certain amount of the enzyme. This suggests that in mutants there may be no structural change in the enzyme gene but the enzyme produced might be less active. By molecular analysis of the mutants' genes it was found that only two mutants induced by thermal neutrons show structural alterations, the changes in other mutants are either too small to be detected by Southern analysis or are outside the structural gene in question. (author)

Estimates of selection parameters in protein mutants of spring barley

International Nuclear Information System (INIS)

Gaul, H.; Walther, H.; Seibold, K.H.; Brunner, H.; Mikaelsen, K.

1976-01-01

Detailed studies have been made with induced protein mutants regarding a possible genetic advance in selection including the estimation of the genetic variation and heritability coefficients. Estimates were obtained for protein content and protein yield. The variation of mutant lines in different environments was found to be many times as large as the variation of the line means. The detection of improved protein mutants seems therefore possible only in trials with more than one environment. The heritability of protein content and protein yield was estimated in different sets of environments and was found to be low. However, higher values were found with an increasing number of environments. At least four environments seem to be necessary to obtain reliable heritability estimates. The geneticall component of the variation between lines was significant for protein content in all environmental combinations. For protein yield some environmental combinations only showed significant differences. The expected genetic advance with one selection step was small for both protein traits. Genetically significant differences between protein micromutants give, however, a first indication that selection among protein mutants with small differences seems also possible. (author)

Complementation of sweet corn mutants: a method for grouping ...

Indian Academy of Sciences (India)

for sweet corn are now expanding and the demands are increasing due to ... tropical/tropical regions of India is amongst one of the factors ... Maize endosperm mutant genes that affect quality of sweet corn can ... Thus, the concept of comple-.

Viral CTL escape mutants are generated in lymph nodes and subsequently become fixed in plasma and rectal mucosa during acute SIV infection of macaques.

Directory of Open Access Journals (Sweden)

Thomas H Vanderford

2011-05-01

Full Text Available SIV(mac239 infection of rhesus macaques (RMs results in AIDS despite the generation of a strong antiviral cytotoxic T lymphocyte (CTL response, possibly due to the emergence of viral escape mutants that prevent recognition of infected cells by CTLs. To determine the anatomic origin of these SIV mutants, we longitudinally assessed the presence of CTL escape variants in two MamuA*01-restricted immunodominant epitopes (Tat-SL8 and Gag-CM9 in the plasma, PBMCs, lymph nodes (LN, and rectal biopsies (RB of fifteen SIV(mac239-infected RMs. As expected, Gag-CM9 did not exhibit signs of escape before day 84 post infection. In contrast, Tat-SL8 escape mutants were apparent in all tissues by day 14 post infection. Interestingly LNs and plasma exhibited the highest level of escape at day 14 and day 28 post infection, respectively, with the rate of escape in the RB remaining lower throughout the acute infection. The possibility that CTL escape occurs in LNs before RBs is confirmed by the observation that the specific mutants found at high frequency in LNs at day 14 post infection became dominant at day 28 post infection in plasma, PBMC, and RB. Finally, the frequency of escape mutants in plasma at day 28 post infection correlated strongly with the level Tat-SL8-specific CD8 T cells in the LN and PBMC at day 14 post infection. These results indicate that LNs represent the primary source of CTL escape mutants during the acute phase of SIV(mac239 infection, suggesting that LNs are the main anatomic sites of virus replication and/or the tissues in which CTL pressure is most effective in selecting SIV escape variants.

Hyperproduction and Thermal Characterization of a Novel Invertase from a Double Mutant Derivative of Kluyveromyces marxianus

Directory of Open Access Journals (Sweden)

Muhammad Ibrahim Rajoka

2011-01-01

Full Text Available Kinetics of intracellular invertase production employing a double mutant derivative of Kluyveromyces marxianus was optimized by varying different process variables in a 23-litre fermentor. The maximum volumetric rate (QP and invertase yield (YP/S by M15 mutant were 1222 U/(L·h and 160 U/g of substrate utilized, respectively (2-fold more than those of parental strain at 50 °C on the molasses (150 g/L of total fermentable sugars at pH=5.5. Glucose or sucrose (100, 150 or 170 g/L did not repress invertase catabolically under the optimized fermentation conditions, contrary to the previous reports on other yeasts and filamentous fungi, where catabolite repression of sugars was predominant. Invertases derived by the wild (IW and mutant (IM strains were purified employing ammonium sulphate precipitation, and then characterized by column chromatographic techniques both kinetically and thermodynamically. The acidic limb of invertases was missing and collation of pKa and the heat of ionization values indicated that carboxyl groups were involved in proton transfer during active catalysis. Ratios of Kcat/Km and vmax/Km indicated that IM was significantly more specific for sucrose hydrolysis. The IM exhibited stability in different buffers at pH=3.0–10.0 and temperature of 50–70 °C, as reflected by long half-lives. IM showed significantly lower values of enthalpy of activation (ΔH* and entropy of activation (ΔS*, while Gibbs free energy (ΔG* was significantly increased at higher temperatures, making the IM thermodynamically more thermostable. Thus IM could be used as a catabolite-resistant invertase for the production of fructose syrup or high gravity ethanol.

A METABOLIC SIGNATURE FOR LONG-LIFE IN THE C. ELEGANS MIT MUTANTS

Science.gov (United States)

Butler, Jeffrey A.; Mishur, Robert J.; Bhaskaran, Shylesh; Rea, Shane L.

2012-01-01

SUMMARY Mit mutations that disrupt function of the mitochondrial electron transport chain can, inexplicably, prolong Caenorhabditis elegans lifespan. In this study we use a metabolomics approach to identify an ensemble of mitochondrial-derived α-ketoacids and α-hydroxyacids that are produced by long-lived Mit mutants but not by other long-lived mutants or by short-lived mitochondrial mutants. We show that accumulation of these compounds is dependent upon concerted inhibition of three α-ketoacid dehydrogenases that share dihydrolipoamide dehydrogenase (DLD) as a common subunit, a protein previously linked in humans with increased risk of Alzheimer’s disease. When the expression of DLD in wild type animals was reduced using RNA interference we observed an unprecedented effect on lifespan - as RNAi dosage was increased lifespan was significantly shortened but, at higher doses, it was significantly lengthened, suggesting DLD plays a unique role in modulating length of life. Our findings provide novel insight into the origin of the Mit phenotype. PMID:23173729

Relations between protein production, protein quality and environmental factors in Pisum mutants

International Nuclear Information System (INIS)

Gottschalk, W.; Mueller, H.P.; Wolff, G.

1975-01-01

The seed protein content of 138 radiation-induced Pisum mutants was determined. The variability of this genetically well-defined material agrees approximately with that of the world collection of Pisum sativum. Some environmental factors to a great extent influence the protein production of the mutants and the initial line. Therefore, it is necessary to consider the relations between the genetically controlled protein production and its dependence upon the environmental factors. This is especially evident if the protein situation of the same genotypes cultivated under the moderate climatic conditions of middle Europe is compared with the subtropical conditions of India. A generally firm correlation between seed size and protein content could not be found in material regarding 148 different mutants of our assortment. Therefore, the selection of small-grained mutants does not result in a selection of protein-rich genotypes in Pisum sativum. Considering all the criteria positively and negatively influencing the protein production, a positive situation could be found in some mutants, especially in the fasciated ones. Furthermore, an improvement of the protein quality could be reached by a genetically conditioned alteration of the globulin-albumin ratio leading to an increase of some essential amino acids such as methionine and lysine. The combined action of mutant genes results in unexpected changes of the protein quantity as well as the quality of the recombinants in relation to their parental mutants. The comparison of some essential amino acids of our useful mutants with those of the varieties of other genera of the Leguminosae shows certain trends of biochemical alterations realized during evolutionary development of the family. (author)

Mutante espontâneo de Bacillus licheniformis bloqueado no estágio I da esporogênese, possuidor de metabolismo respiratório aumentado A spontaneous mutant of Bacillus licheniformis with increased respiratory metabolism, blocked in stage I of sporogenesis

Directory of Open Access Journals (Sweden)

Leon Rabinovitch

1976-01-01

Full Text Available Um mutante espontâneo de Bacillus licheniformis, derivado da amostra esporogênica 2390, foi estudado com vistas ao reconhecimento do estágio da evolução para esporo em que o mesmo se encontrava bloqueado. Eletronmicrografias sugeriram que as células desse mutante, colhidas durante a fase estacionária da curva de crescimento, não ultrapassaram o estágio I da esporogênese (i.e., permaneceram com o nucleóide disposto como filamento axial, enquanto a produção de antibiótico (bacitracina e a atividade proteolítica foram francamente detectadas. A linhagem mutante, designada Spolp-72, nas condições experimentais empregadas não biossintetizou esporos por estarvação em solução de sais inorgãnicos, mas evidenciou uma frequência de esporulação menor que 10*-7, após crescimento vegetativo em meio de cultura favorável á esporogênese. A amostra Spolp-72 externa um crescimento vegetativo inicial restringido, quando comparada com a amostra 2390, enquanto que, inversamente, sua atividade respiratória é significativamente mais elevada. Este último comportamento foi confirmado no presente trabalho, contrastando, nesse particular, com outros tipos de mutantes de esporulação já descritos, os quais se encontram bloqueados nos primeiros estágios da via esporogenética.A spontaneous mutant strain derived from the sporogenic B. licheniformis 2390 was studied with a view to determining at what developmental stage toward sporulation it was blocked. Electronmicrographs suggested that the mutant cells harvested during the stationary phase of the growth curve were unable to go beyond stage I of sporogenesis (i. e., their nucleoid remained as an axial filament. On the other hand, antibiotic production (bacitracin and proteolytic activity were easily detected. Under the present experimental conditions the mutant strain, named Spolp-72, did not synthesize spores by starvation in a solution of inorganic salts, in contrast with the parental

Booster vaccination with safe, modified, live-attenuated mutants of Brucella abortus strain RB51 vaccine confers protective immunity against virulent strains of B. abortus and Brucella canis in BALB/c mice.

Science.gov (United States)

Truong, Quang Lam; Cho, Youngjae; Kim, Kiju; Park, Bo-Kyoung; Hahn, Tae-Wook

2015-11-01

Brucella abortus attenuated strain RB51 vaccine (RB51) is widely used in prevention of bovine brucellosis. Although vaccination with this strain has been shown to be effective in conferring protection against bovine brucellosis, RB51 has several drawbacks, including residual virulence for animals and humans. Therefore, a safe and efficacious vaccine is needed to overcome these disadvantages. In this study, we constructed several gene deletion mutants (ΔcydC, ΔcydD and ΔpurD single mutants, and ΔcydCΔcydD and ΔcydCΔpurD double mutants) of RB51 with the aim of increasing the safety of the possible use of these mutants as vaccine candidates. The RB51ΔcydC, RB51ΔcydD, RB51ΔpurD, RB51ΔcydCΔcydD and RB51ΔcydCΔpurD mutants exhibited significant attenuation of virulence when assayed in murine macrophages in vitro or in BALB/c mice. A single intraperitoneal immunization with RB51ΔcydC, RB51ΔcydD, RB51ΔcydCΔcydD or RB51ΔcydCΔpurD mutants was rapidly cleared from mice within 3 weeks, whereas the RB51ΔpurD mutant and RB51 were detectable in spleens until 4 and 7 weeks, respectively. Vaccination with a single dose of RB51 mutants induced lower protective immunity in mice than did parental RB51. However, a booster dose of these mutants provided significant levels of protection in mice against challenge with either the virulent homologous B. abortus strain 2308 or the heterologous Brucella canis strain 26. In addition, these mutants were found to induce a mixed but T-helper-1-biased humoral and cellular immune response in immunized mice. These data suggest that immunization with a booster dose of attenuated RB51 mutants provides an attractive strategy to protect against either bovine or canine brucellosis.

GH and IGF1: Roles in Energy Metabolism of Long-Living GH Mutant Mice

OpenAIRE

Brown-Borg, Holly M.; Bartke, Andrzej

2012-01-01

Of the multiple theories to explain exceptional longevity, the most robust of these has centered on the reduction of three anabolic protein hormones, growth hormone (GH), insulin-like growth factor, and insulin. GH mutant mice live 50% longer and exhibit significant differences in several aspects of energy metabolism as compared with wild-type mice. Mitochondrial metabolism is upregulated in the absence of GH, whereas in GH transgenic mice and dwarf mice treated with GH, multiple aspects of t...

Metabolic Engineering of Light and Dark Biochemical Pathways in Wild-Type and Mutant Strains of Synechocystis PCC 6803 for Maximal, 24-Hour Production of Hydrogen Gas

Energy Technology Data Exchange (ETDEWEB)

Ely, Roger L.; Chaplen, Frank W.R.

2014-03-11

enhanced H2 production profiles using selected culture conditions and inhibitors of specific pathways in WT cells and an NDH-1 mutant; 3. Create Synechocystis PCC 6803 mutant strains with modified hydrogenases exhibiting increased O2 tolerance and greater H2 production; and 4. Integrate enhanced hydrogenase mutants and culture and metabolic factor studies to maximize 24-hour H2 production.

Phenotypic, genetic and molecular characterization of a maize low phytic acid mutant (lpa241)

DEFF Research Database (Denmark)

Pilu, R.; Panzeri, D.; Gavazzi, G.

2003-01-01

-nutritional factor for animals, and isolation of maize low phytic acid (lpa) mutants provides a novel approach to study its biochemical pathway and to tackle the nutritional problems associated with it. Following chemical mutagenesis of pollen, we have isolated a viable recessive mutant named lpa 241 showing about...... 90% reduction of phytic acid and about a tenfold increase in seed-free phosphate content. Although germination rate was decreased by about 30% compared to wild-type, developement of mutant plants was apparentely unaffected. The results of the genetic, biochemical and molecular characterization...

Yield potential of a radiation induced early-dwarf mutant in linseed

International Nuclear Information System (INIS)

Nayar, G.G.

1975-01-01

An early maturing dwarf mutant, TL-1 was isolated in the high yielding linseed (Linum usitatissimum L.) wariety Neelum following seed irradiation with 50 kR gamma rays. The yield components of the mutant have been evaluated for its productivity in the M 7 generation. TL-1 is compact and significantly short in height (41.8 +- 2.71 cm) as compared to Neelum (79.2 +- 3.08 cm). In flowering the mutant is 30 days earlier than the parent under Trombay conditions. TL-1 and Neelum did not differ significantly in their mean number of primary branches. Although the mean seed yield per plant is lower, in 1000 seed weight the mutant is markedly superior to the parent. The oil content in TL-1 is significantly higher by 3.5 percent points than Neelum and its oil is lighter in colour. By growing more plants per unit area with reduced spacing, the yield potential of TL-1 was considerably increased. The productivity of oil per hectare per day of TL-1 was higher than Neelum. (author)

Molybdenum x-ray absorption studies of the mutant Kp nifV of nitrogenase MO-FE protein

International Nuclear Information System (INIS)

Eidsness, M.K.; Smith, B.E.; Flood, A.C.; Garner, C.D.; Cramer, S.P.

1985-01-01

The nifV mutant nitrogenase enzyme of Klebsiella pheumoniae exhibits altered substrate reducing activity. This nitrogenase mutant cannot fix N 2 in vivo but can reduce C 2 H 2 to C 2 H 4 . The nifV mutant enzyme differs further from the wild-type enzyme by CO inhibition of its H 2 evolution activity, up to 80%. The NifV - phenotype (NifV - Kp1) has been shown to be associated with the iron-molybdenum cofactor (FeMoco) in the Mo Fe protein which is generally accepted as the site for substrate reduction. An X-Ray absorption study of the Mo site in this mutant may reveal a difference in its FeMoco structure. The authors report here a comparison of Mo X-Ray absorption data from the nitrogenase enzymes of the wild-type and NifV - strains in three different forms: (1) as isolated, (2) dye-oxidized, and (3) fixing enzyme systems. Mo edge structure of NifV - Kp1 and wild-type enzymes are nearly identical. Small shifts to higher energies are observed in the oxidized and fixing states. Mo EXAFS of NifV - Kp1 and wild-type in the ''as isolated'' state appear indistinguishable. Curve fitting results best describe the molybdenum in FeMoco as bound by 4-5 S atoms at 2.36 A ,3 Fe atoms at 2.69 A, and 0-2 O(N) atoms at 2.19 A. The spectral similarity of these results concerning the nifV mutant FeMoco structure is discussed

Phenotypic characterization of adenovirus type 12 temperature-sensitive mutants in productive infection and transformation.

Science.gov (United States)

Hama, S; Kimura, G

1980-01-01

Eleven temperature-sensitive mutants of adenovirus type 12, capable of forming plaques in human cells at 33 C but not at 39.5 C, were isolated from a stock of a wild-type strain after treatment with either nitrous acid or hydroxylamine. Complementation tests in doubly infected human cells permitted a tentative assignment of eight of these mutants to six complementation groups. Temperature-shift experiments revealed that one mutant is affected early and most of the other mutants are affected late. Only the early mutant, H12ts505, was temperature sensitive in viral DNA replication. Infectious virions of all the mutants except H12ts505 and two of the late mutants produced at 33 C, appeared to be more heat labile than those of the wild type. Only H12ts505 was temperature sensitive for the establishment of transformation of rat 3Y1 cells. One of the late mutants (H12ts504) had an increased transforming ability at the permissive temperature. Results of temperature-shift transformation experiments suggest that a viral function affected in H12ts505 is required for "initiation" of transformation. Some of the growth properties of H12ts505-transformed cells were also temperature dependent, suggesting that a functional expression of a gene mutation in H12ts505 is required to maintain at least some aspects of the transformed state.

Low-energy N-ion beam biotechnology application in the induction of Thai jasmine rice mutant with improved seed storability

Science.gov (United States)

Semsang, Nuananong; Techarang, Jiranat; Yu, Liangdeng; Phanchaisri, Boonrak

2018-06-01

Low-energy heavy-ion beam is a novel biotechnology used for mutation induction in plants. We used a low-energy N-ion beam to induce mutations in Thai jasmine rice (Oryza sativa L. cv. KDML 105) to improve the yield and seed quality. Seeds of BKOS6, a Thai jasmine rice mutant previously induced by ion beams, were re-bombarded with 60-kV-accelerated N-ions (N++N2+) to fluences of 1-2 × 1016 ions/cm2. The resulting mutant, named HyKOS21, exhibited photoperiod insensitivity, semi-dwarfness, and high yield potential. Seed storability of the mutant was studied in natural and accelerated ageing conditions and compared to that of KDML 105 and six other Thai rice varieties. In both testing conditions, HyKOS21 mutant had the highest seed storability among the tested varieties. After storage in the natural condition for 18 months, HyKOS21 had a seed germination percentage nearly two times as that of the original KDML 105. Biochemical analysis showed that the lipid peroxidation level of the mutant seeds was the lowest among those of the tested varieties. Furthermore, an expression analysis of genes encoding lipoxygenase isoenzyme (lox1, lox2, and lox3) revealed that the mutant lacked expression of lox1 and lox2 and expressed only lox3 in seeds. These results may explain the improved seed longevity of the mutant after storage. This work provides further evidence of the modification of biological materials using a low-energy ion beam to produce rice mutants with improved yield and seed storability. The benefits of this technology, to create new varieties with improved values, could serve for local economic development.

High yielding mutants of blackgram variety 'PH-25'

International Nuclear Information System (INIS)

Misra, R.C.; Mohapatra, B.D.; Panda, B.S.

2001-01-01

Seeds of blackgram (Vigna mungo L.) variety 'PH-5' were treated with chemical mutagens ethyl methanesulfonate (EMS), nitrosoguanidine (NG), maleic hydrazide (MH) and sodium azide (NaN 3 ), each at 3 different concentrations. Thirty six mutant lines developed from mutagenic treatments along with parent varieties were tested in M 4 generation. The mutants showed wide variation in most of the traits and multivariante D 2 analysis showed genetic divergence among themselves. Twenty of the thirty mutants showed genetic divergence from parent. Ten selected high yielding mutants were tested in M 5 . Yield and other productive traits of five high yielding mutants in M 4 and M 5 are presented

Isolation and partial characterization of mutants with elevated lipid content in Chlorella sorokiniana and Scenedesmus obliquus.

Science.gov (United States)

Vigeolas, Hélène; Duby, Francéline; Kaymak, Esra; Niessen, Guillaume; Motte, Patrick; Franck, Fabrice; Remacle, Claire

2012-11-30

This paper describes the isolation and partial biomass characterization of high triacylglycerol (TAG) mutants of Chlorella sorokiniana and Scenedesmus obliquus, two algal species considered as potential source of biodiesel. Following UV mutagenesis, 2000 Chlorella and 2800 Scenedesmus colonies were screened with a method based on Nile Red fluorescence. Several mutants with high Nile Red fluorescence were selected by this high-throughput method in both species. Growth and biomass parameters of the strongest mutants were analyzed in detail. All of the four Chlorella mutants showed no significant changes in growth rate, cell weight, cell size, protein and chlorophyll contents on a per cell basis. Whereas all contained elevated total lipid and TAG content per unit of dry weight, two of them were also affected for starch metabolism, suggesting a change in biomass/storage carbohydrate composition. Two Scenedesmus mutants showed a 1.5 and 2-fold increased cell weight and larger cells compared to the wild type, which led to a general increase of biomass including total lipid and TAG content on a per cell basis. Such mutants could subsequently be used as commercial oleaginous algae and serve as an alternative to conventional petrol. Copyright © 2012 Elsevier B.V. All rights reserved.

Some biochemistry characteristics of soja (Glycine Max.L.) Tshibashi and its two mutants

International Nuclear Information System (INIS)

Botula, Manyala; Kasende, Mundeke; Kembola, Kejuni.

1978-01-01

Two mutants of a variety of soybeans (Thibashi) obtained by neutron irradiation in a reactor have been compared to their parents for their proteins and lipids contents. Analysis have been made by a modified micro-kjedhal method for proteins and by gaz chromatography for lipids converted into methylic esters. A slight lysine and hyptidine increase and a slight linolenic acid decrease are observed in the two mutants

Gamma-radiation Mutagenesis in Genetically Unstable Barley Mutants. Pt. 1. Chlorophyll Mutations in Allelic tw Mutants and Their Revertants

International Nuclear Information System (INIS)

Vaitkuniene, V.

1995-01-01

Genotypical environment is an essential factor determining the mutability of mutants of the same type. Decreased chlorophyll mutant frequency was a common characteristic of all tested tw type (tw, tw 1 , tw 2 ) mutants induced in barley c. 'Auksiniai II'. The mutability of all the tested revertants was close to that of the initial c. 'Auksiniai II'. (author). 9 refs., 2 tabs

Long-lived mitochondrial (Mit) mutants of Caenorhabditis elegans utilize a novel metabolism.

Science.gov (United States)

Butler, Jeffrey A; Ventura, Natascia; Johnson, Thomas E; Rea, Shane L

2010-12-01

The Caenorhabditis elegans mitochondrial (Mit) mutants have disrupted mitochondrial electron transport chain (ETC) functionality, yet, surprisingly, they are long lived. We have previously proposed that Mit mutants supplement their energy needs by exploiting alternate energy production pathways normally used by wild-type animals only when exposed to hypoxic conditions. We have also proposed that longevity in the Mit mutants arises as a property of their new metabolic state. If longevity does arise as a function of metabolic state, we would expect to find a common metabolic signature among these animals. To test these predictions, we established a novel approach monitoring the C. elegans exometabolism as a surrogate marker for internal metabolic events. Using HPLC-ultraviolet-based metabolomics and multivariate analyses, we show that long-lived clk-1(qm30) and isp-1(qm150) Mit mutants have a common metabolic profile that is distinct from that of aerobically cultured wild-type animals and, unexpectedly, wild-type animals cultured under severe oxygen deprivation. Moreover, we show that 2 short-lived mitochondrial ETC mutants, mev-1(kn1) and ucr-2.3(pk732), also share a common metabolic signature that is unique. We show that removal of soluble fumarate reductase unexpectedly increases health span in several genetically defined Mit mutants, identifying at least 1 alternate energy production pathway, malate dismutation, that is operative in these animals. Our study suggests long-lived, genetically specified Mit mutants employ a novel metabolism and that life span may well arise as a function of metabolic state.

TOMATOMA Update: Phenotypic and Metabolite Information in the Micro-Tom Mutant Resource.

Science.gov (United States)

Shikata, Masahito; Hoshikawa, Ken; Ariizumi, Tohru; Fukuda, Naoya; Yamazaki, Yukiko; Ezura, Hiroshi

2016-01-01

TOMATOMA (http://tomatoma.nbrp.jp/) is a tomato mutant database providing visible phenotypic data of tomato mutant lines generated by ethylmethane sulfonate (EMS) treatment or γ-ray irradiation in the genetic background of Micro-Tom, a small and rapidly growing variety. To increase mutation efficiency further, mutagenized M3 seeds were subjected to a second round of EMS treatment; M3M1 populations were generated. These plants were self-pollinated, and 4,952 lines of M3M2 mutagenized seeds were generated. We checked for visible phenotypes in the M3M2 plants, and 618 mutant lines with 1,194 phenotypic categories were identified. In addition to the phenotypic information, we investigated Brix values and carotenoid contents in the fruits of individual mutants. Of 466 samples from 171 mutant lines, Brix values and carotenoid contents were between 3.2% and 11.6% and 6.9 and 37.3 µg g(-1) FW, respectively. This metabolite information concerning the mutant fruits would be useful in breeding programs as well as for the elucidation of metabolic regulation. Researchers are able to browse and search this phenotypic and metabolite information and order seeds of individual mutants via TOMATOMA. Our new Micro-Tom double-mutagenized populations and the metabolic information could provide a valuable genetic toolkit to accelerate tomato research and potential breeding programs. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

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

Science.gov (United States)

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.

Characterization of novel Sorghum brown midrib mutants from an EMS-mutagenized population.

Science.gov (United States)

Sattler, Scott E; Saballos, Ana; Xin, Zhanguo; Funnell-Harris, Deanna L; Vermerris, Wilfred; Pedersen, Jeffrey F

2014-09-02

Reducing lignin concentration in lignocellulosic biomass can increase forage digestibility for ruminant livestock and saccharification yields of biomass for bioenergy. In sorghum (Sorghum bicolor (L.) Moench) and several other C4 grasses, brown midrib (bmr) mutants have been shown to reduce lignin concentration. Putative bmr mutants isolated from an EMS-mutagenized population were characterized and classified based on their leaf midrib phenotype and allelism tests with the previously described sorghum bmr mutants bmr2, bmr6, and bmr12. These tests resulted in the identification of additional alleles of bmr2, bmr6, and bmr12, and, in addition, six bmr mutants were identified that were not allelic to these previously described loci. Further allelism testing among these six bmr mutants showed that they represented four novel bmr loci. Based on this study, the number of bmr loci uncovered in sorghum has doubled. The impact of these lines on agronomic traits and lignocellulosic composition was assessed in a 2-yr field study. Overall, most of the identified bmr lines showed reduced lignin concentration of their biomass relative to wild-type (WT). Effects of the six new bmr mutants on enzymatic saccharification of lignocellulosic materials were determined, but the amount of glucose released from the stover was similar to WT in all cases. Like bmr2, bmr6, and bmr12, these mutants may affect monolignol biosynthesis and may be useful for bioenergy and forage improvement when stacked together or in combination with the three previously described bmr alleles. Copyright © 2014 Sattler et al.

Phenotypic, fermentation characterization, and resistance mechanism analysis of bacteriophage-resistant mutants of Lactobacillus delbrueckii ssp. bulgaricus isolated from traditional Chinese dairy products.

Science.gov (United States)

Deng, Kaibo; Fang, Wei; Zheng, Baodong; Miao, Song; Huo, Guicheng

2018-03-01

Bacteriophage infection is a large factor in dairy industrial production failure on the basis of pure inoculation fermentation, and developing good commercial starter cultures from wild dairy products and improving the environmental vigor of starter cultures by enhancing their phage resistance are still the most effective solutions. Here we used a spontaneous isolation method to obtain bacteriophage-resistant mutants of Lactobacillus delbrueckii ssp. bulgaricus strains that are used in traditional Chinese fermented dairy products. We analyzed their phenotypes, fermentation characteristics, and resistance mechanisms. The results showed that bacteriophage-insensitive mutants (BIM) BIM8 and BIM12 had high bacteriophage resistance while exhibiting fermentation and coagulation attributes that were as satisfying as those of their respective parent strains KLDS1.1016 and KLDS1.1028. According to the attachment receptor detection, mutants BIM8 and BIM12 exhibited reduced absorption to bacteriophage phiLdb compared with their respective bacteriophage-sensitive parent strains because of changes to the polysaccharides or teichoic acids connected to their peptidoglycan layer. Additionally, genes, including HSDR, HSDM, and HSDS, encoding 3 subunits of a type I restriction-modification system were identified in their respective parent strains. We also discovered that HSDR and HSDM were highly conserved but that HSDS was variable because it is responsible for the DNA specificity of the complex. The late lysis that occurred only in strain KLDS1.1016 and not in strain KLDS1.1028 suggests that the former and its mutant BIM8 also may have an activatable restriction-modification mechanism. We conclude that the L. bulgaricus BIM8 and BIM12 mutants have great potential in the dairy industry as starter cultures, and their phage-resistance mechanism was effective mainly due to the adsorption interference and restriction-modification system. Copyright © 2018 American Dairy Science

Molecular analysis of mutants of the Neurospora adenylosuccinate ...

Indian Academy of Sciences (India)

2012-08-07

Aug 7, 2012 ... and mutants induced with X-ray, UV or chemical mutagens. ... We have sequenced the ad-8 locus from 13 of these mutants and identified the molecular nature ..... mutants in yeast by selection for constitutive behavior in pig-.

Induced mutants of Streptococcus lactis by gamma irradiation and its effect on milk acidity

International Nuclear Information System (INIS)

Daowd, A.H.; Sabbour, M.M.; Newigy, N.A.; Wahab, G.A.M.

1988-01-01

Streptococus lactis was exposed to different doses of gamma-irradiation (10, 50, 100 and 150 Kr). The results of acidity production in sterilized milk inoculated by isolates from radiation treatments and control could be summarized in the following: 1. The mean acidity produced by S. lactis isolates after irradiation at 10 Kr increased to be 0.66% than that of control isolates (0.62%). The acidity produced by the isolates of the 50 Kr treatment showed more increment to reach the peak (0.7%). Thereafter, acidity production decreased by isolates of the 100 Kr (0.53%) and 150 Kr (0.51%) treatments. Heme, the 50 Kr treatment could be considered activation dose to S. lactis starter for acid production. 2. Two mutants were selected. Acidity production by mutant I (from 10 Kr treatment) was 0.95%, and that of mutant II (from 50 Kr treatment) was 1.0%, while acid production by the parent S. lactis culture was 0.62%. Concerning the stability of the isolates, it was found that acid production by mutant I and mutant II slightly decreased by time. The mutants were re-irradiated after 37 and 60 days at doses 10, 25 and 50 Kr. Acid production in milk by isolates of the radiation treatments was determined. The following results were obtained: -The re-irradiation of the mutants decreased the ability of the isolates for acid production than that of parent mutants. -The re-irradiation of the mutants after 60 days yielded isolates which showed more reduction in acid produced than of isolates obtained from re-irridation of the mutants after 37-days. -The higher the dose of the re-irradiation of the mutants, the lower the mean of acid production by isolates of the treatment

Gamma-ray induced mutants in castor (Ricinus communis L.)

International Nuclear Information System (INIS)

Janila, P.; Ashok Kumar, A.; Rajashekar Reddy, N.; Hemalatha, V.

2007-01-01

We report isolation of three recessive mutants in castor using dry seed irradiation with gamma rays. The crinkled leaf mutant (crf) was identified in K-55-112 M2 family and leafy mutant (lea) in H-55-577 M2 family; both are recessive lethal and thus maintained as heterozygotes. The cri mutant has highly wrinkled leaves resembling finger millet head and failed to enter reproductive phase, consequently did not produce seeds. The number of leaf lobes is reduced in lea mutant and though it produced spikes, the male and female flowers are converted to leafy appendages. The third mutant, fused (Ius) stem identified in H-55-617 M2 family is a recessive mutant. The branches of which are fused at the base and though each branch terminates in to monoceous spike like normal plant, the spike is highly condensed. The three mutants under report are valuable genetic stocks for development of linkage maps in castor, which is at infancy. (author)

Effects of mutant human Ki-rasG12C gene dosage on murine lung tumorigenesis and signaling to its downstream effectors

International Nuclear Information System (INIS)

Dance-Barnes, Stephanie T.; Kock, Nancy D.; Floyd, Heather S.; Moore, Joseph E.; Mosley, Libyadda J.; D'Agostino, Ralph B.; Pettenati, Mark J.; Miller, Mark Steven

2008-01-01

Studies in cell culture have suggested that the level of RAS expression can influence the transformation of cells and the signaling pathways stimulated by mutant RAS expression. However, the levels of RAS expression in vivo appear to be subject to feedback regulation, limiting the total amount of RAS protein that can be expressed. We utilized a bitransgenic mouse lung tumor model that expressed the human Ki-ras G12C allele in a tetracycline-inducible, lung-specific manner. Treatment for 12 months with 500 μg/ml of doxycycline (DOX) allowed for maximal expression of the human Ki-ras G12C allele in the lung, and resulted in the development of focal hyperplasia and adenomas. We determined if different levels of mutant RAS expression would influence the phenotype of the lung lesions. Treatment with 25, 100 and 500 μg/ml of DOX resulted in dose-dependent increases in transgene expression and tumor multiplicity. Microscopic analysis of the lungs of mice treated with the 25 μg/ml dose of DOX revealed infrequent foci of hyperplasia, whereas mice treated with the 100 and 500 μg/ml doses exhibited numerous hyperplastic foci and also adenomas. Immunohistochemical and RNA analysis of the downstream effector pathways demonstrated that different levels of mutant RAS transgene expression resulted in differences in the expression and/or phosphorylation of specific signaling molecules. Our results suggest that the molecular alterations driving tumorigenesis may differ at different levels of mutant Ki-ras G12C expression, and this should be taken into consideration when inducible transgene systems are utilized to promote tumorigenesis in mouse models

Productive mutants of niger

International Nuclear Information System (INIS)

Misra, R.C.

2001-01-01

Seeds of six niger (Guizotia abyssinica Cass.) varieties ('GA-10', 'ONS-8', 'IGP-72', 'N-71', 'NB-9' and 'UN-4') were treated with 0.5, 0.75 and 1% ethyl methanesulphonate. After four generations of selection, 29 mutant lines were developed and those were evaluated from 1990-92 during Kharif (July to October) and Rabi (December to March) seasons. Average plant characteristics and yield data of four high yielding mutants along with 'IGP-76' (National Check), GA-10 (Zonal Check) and 'Semiliguda Local' (Local Check) are presented

Proteomic Analysis of Anti-Cancerous Scopularide Production by a Marine Microascus brevicaulis Strain and Its UV Mutant

DEFF Research Database (Denmark)

Kramer, Annemarie; Beck, Hans Christian; Kumar, Abhishek

2015-01-01

The marine fungus Microascus brevicaulis strain LF580 is a non-model secondary metabolite producer with high yields of the two secondary metabolites scopularides A and B, which exhibit distinct activities against tumour cell lines. A mutant strain was obtained using UV mutagenesis, showing faster...... for optimisation on strain and process level. The linkage between nutrient limitation and pellet formation in the non-model fungus M. brevicaulis is in consensus with the knowledge on model organisms like Aspergillus niger and Penicillium chrysogenum....... growth and differences in pellet formation besides higher production levels. Here, we show the first proteome study of a marine fungus. Comparative proteomics were applied to gain deeper understanding of the regulation of production and of the physiology of the wild type strain and its mutant...... in the mutant strain: 189 were down- and 129 upregulated. Proteomics are a powerful tool for the understanding of regulatory aspects: The differences on proteome level could be attributed to limited nutrient availability in the wild type strain due to a strong pellet formation. This information can be applied...

Metabolic characterization of isocitrate dehydrogenase (IDH) mutant and IDH wildtype gliomaspheres uncovers cell type-specific vulnerabilities.

Science.gov (United States)

Garrett, Matthew; Sperry, Jantzen; Braas, Daniel; Yan, Weihong; Le, Thuc M; Mottahedeh, Jack; Ludwig, Kirsten; Eskin, Ascia; Qin, Yue; Levy, Rachelle; Breunig, Joshua J; Pajonk, Frank; Graeber, Thomas G; Radu, Caius G; Christofk, Heather; Prins, Robert M; Lai, Albert; Liau, Linda M; Coppola, Giovanni; Kornblum, Harley I

2018-01-01

There is considerable interest in defining the metabolic abnormalities of IDH mutant tumors to exploit for therapy. While most studies have attempted to discern function by using cell lines transduced with exogenous IDH mutant enzyme, in this study, we perform unbiased metabolomics to discover metabolic differences between a cohort of patient-derived IDH1 mutant and IDH wildtype gliomaspheres. Using both our own microarray and the TCGA datasets, we performed KEGG analysis to define pathways differentially enriched in IDH1 mutant and IDH wildtype cells and tumors. Liquid chromatography coupled to mass spectrometry analysis with labeled glucose and deoxycytidine tracers was used to determine differences in overall cellular metabolism and nucleotide synthesis. Radiation-induced DNA damage and repair capacity was assessed using a comet assay. Differences between endogenous IDH1 mutant metabolism and that of IDH wildtype cells transduced with the IDH1 (R132H) mutation were also investigated. Our KEGG analysis revealed that IDH wildtype cells were enriched for pathways involved in de novo nucleotide synthesis, while IDH1 mutant cells were enriched for pathways involved in DNA repair. LC-MS analysis with fully labeled 13 C-glucose revealed distinct labeling patterns between IDH1 mutant and wildtype cells. Additional LC-MS tracing experiments confirmed increased de novo nucleotide synthesis in IDH wildtype cells relative to IDH1 mutant cells. Endogenous IDH1 mutant cultures incurred less DNA damage than IDH wildtype cultures and sustained better overall growth following X-ray radiation. Overexpression of mutant IDH1 in a wildtype line did not reproduce the range of metabolic differences observed in lines expressing endogenous mutations, but resulted in depletion of glutamine and TCA cycle intermediates, an increase in DNA damage following radiation, and a rise in intracellular ROS. These results demonstrate that IDH1 mutant and IDH wildtype cells are easily distinguishable

Isolation and characterization of MMS-sensitive mutants of Saccharomyces cerevisiae

International Nuclear Information System (INIS)

Prakash, L.; Prakash, S.

1977-01-01

We have isolated mutants sensitive to methyl methanesulfonate (MMS) in Saccharomyces cerevisiae. Alleles of rad1, rad4, rad6, rad52, rad55 and rad57 were found among these mms mutants. Twenty-nine of the mms mutants which complement the existing radiation-sensitive (rad and rev) mutants belong to 22 new complementation groups. Mutants from five complementation groups are sensitive only to MMS. Mutants of 11 complementation groups are sensitive to uv or x rays in addition to MMS, mutants of six complementation groups are sensitive to all three agents. The cross-sensitivities of these mms mutants to uv and x rays are discussed in terms of their possible involvement in DNA repair. Sporulation is reduced or absent in homozygous diploids of mms mutants from nine complementation groups

Identification of a Gravitropism-Deficient Mutant in Rice

Directory of Open Access Journals (Sweden)

He Yan

2017-03-01

Full Text Available A gravitropism-deficient mutant M96 was isolated from a mutant bank, generated by ethyl methane sulfonate (EMS mutagenesis of indica rice accession ZJ100. The mutant was characterized as prostrate growth at the beginning of germination, and the prostrate growth phenotype ran through the whole life duration. Tiller angle and tiller number of M96 increased significantly in comparison with the wild type. Tissue section observation analysis indicated that asymmetric stem growth around the second node occurred in M96. Genetic analysis and gene mapping showed that M96 was controlled by a single recessive nuclear gene, tentatively termed as gravitropism-deficient M96 (gdM96, which was mapped to a region of 506 kb flanked by markers RM5960 and InDel8 on the long arm of chromosome 11. Sequencing analysis of the open reading frames in this region revealed a nucleotide substitution from G to T in the third exon of LOC_Os11g29840. Additionally, real-time fluorescence quantitative PCR analysis showed that the expression level of LOC_Os11g29840 in the stems was much higher than in the roots and leaves in M96. Furthermore, the expression level was more than four times in M96 stem than in the wild type stem. Our results suggested that the mutant gene was likely a new allele to the reported gene LAZY1. Isolation of this new allele would facilitate the further characterization of LAZY1.

Isoenzymes performance of some rice varieties and their mutants

International Nuclear Information System (INIS)

Winarno, Ermin; Suliwarno, Ambyah; Ismachin, M.

1992-01-01

Isoenzymes performance of some rice varieties and their mutants. Genetics studies on alcohol dehydrogenase, malic enzyme, peroxidase, acid phosphase, and aminopeptidase isoenzymes were carried out on several groups of rice varieties and their mutant lines. The first groups consisted of Atomita I, Pelita I/1, A227/5, Mudgo, TN-1, and IR-26. The second group was Cisadane variety and its five mutants, namely OBS 18, OBS 208, OBS 297, OBS 306, and OBS 330. The third group was mutants line 627-10-3 and its mutants, namely 1063, 1066, 1067, 1076, and 1090. Isoenzymes extracts of the rice leaves were fractionated using polyacrylamide gel disc electrophoresis. The pattern of acid phosphate isoenzyme shows the specific character of rice mutants susceptible to brown plant hopper biotype 1. The gene(s) controlling malic enzyme in Cisadane's mutants is (are) estimated more resistant toward gamma irradiation than gene(s) responsible for controlling the other enzymes. Generally, the isoenzymes zymograms show that gene(s) controlling the mutants enzyme have undergone mutation. This case is shown by the changes of Rm value, as well as the amount and intensity of mutants bands. (authors). 7 refs., 7 figs

Differential chromosomal and mitochondrial DNA synthesis in temperature-sensitive mutants of Ustilago maydis

Energy Technology Data Exchange (ETDEWEB)

Unrau, P.

1977-01-01

The amount and type of residual DNA synthesis was determined in eight temperature-sensitive mutants of the smut fungus Ustilago maydis after incubation at the restrictive temperature (32/sup 0/C) for eight hours. Mutants ts-220, ts-207, ts-432 and ts-346 were found to have an overall reduction in the synthesis of both nuclear and mitochondrial DNA in comparison to the wild-type. In mutants ts-20, tsd 1-1, ts-84 and pol 1-1 nuclear DNA synthesis was depressed relative to mitochondrial synthesis. The DNA-polymerase mutant pol 1-1 had persistent nuclear synthesis at about 50% of the rate of synthesis of mitochondrial DNA and similar behavior was observed in a diploid homozygous strain. Mutant ts-84 had an initial burst of DNA synthesis which was reduced for nuclear but not mitochondrial synthesis after three hours preincubation at 32/sup 0/C. tsd 1-1 and ts-20 had nuclear residual synthesis amounting to about 25% of the relative rate of mitochondrial synthesis which correlates to increasing UV sensitivity of these strains on incubation at 32/sup 0/C. A pol 1-1 ts-84 double mutant had an additive loss of nuclear DNA synthesis which indicates that the steps of replication involved may be sequential.

A comprehensive dataset of genes with a loss-of-function mutant phenotype in Arabidopsis.

Science.gov (United States)

Lloyd, Johnny; Meinke, David

2012-03-01

Despite the widespread use of Arabidopsis (Arabidopsis thaliana) as a model plant, a curated dataset of Arabidopsis genes with mutant phenotypes remains to be established. A preliminary list published nine years ago in Plant Physiology is outdated, and genome-wide phenotype information remains difficult to obtain. We describe here a comprehensive dataset of 2,400 genes with a loss-of-function mutant phenotype in Arabidopsis. Phenotype descriptions were gathered primarily from manual curation of the scientific literature. Genes were placed into prioritized groups (essential, morphological, cellular-biochemical, and conditional) based on the documented phenotypes of putative knockout alleles. Phenotype classes (e.g. vegetative, reproductive, and timing, for the morphological group) and subsets (e.g. flowering time, senescence, circadian rhythms, and miscellaneous, for the timing class) were also established. Gene identities were classified as confirmed (through molecular complementation or multiple alleles) or not confirmed. Relationships between mutant phenotype and protein function, genetic redundancy, protein connectivity, and subcellular protein localization were explored. A complementary dataset of 401 genes that exhibit a mutant phenotype only when disrupted in combination with a putative paralog was also compiled. The importance of these genes in confirming functional redundancy and enhancing the value of single gene datasets is discussed. With further input and curation from the Arabidopsis community, these datasets should help to address a variety of important biological questions, provide a foundation for exploring the relationship between genotype and phenotype in angiosperms, enhance the utility of Arabidopsis as a reference plant, and facilitate comparative studies with model genetic organisms.

Comparative Global Gene Expression Profiles of Wild-Type Yersinia pestis CO92 and Its Braun Lipoprotein Mutant at Flea and Human Body Temperatures

Directory of Open Access Journals (Sweden)

Cristi L. Galindo

2010-01-01

Full Text Available Braun/murein lipoprotein (Lpp is involved in inflammatory responses and septic shock. We previously characterized a Δlpp mutant of Yersinia pestis CO92 and found that this mutant was defective in surviving in macrophages and was attenuated in a mouse inhalation model of plague when compared to the highly virulent wild-type (WT bacterium. We performed global transcriptional profiling of WT Y. pestis and its Δlpp mutant using microarrays. The organisms were cultured at 26 and 37 degrees Celsius to simulate the flea vector and mammalian host environments, respectively. Our data revealed vastly different effects of lpp mutation on the transcriptomes of Y. pestis grown at 37 versus 26C. While the absence of Lpp resulted mainly in the downregulation of metabolic genes at 26C, the Y. pestis Δlpp mutant cultured at 37C exhibited profound alterations in stress response and virulence genes, compared to WT bacteria. We investigated one of the stress-related genes (htrA downregulated in the Δlpp mutant relative to WT Y. pestis. Indeed, complementation of the Δlpp mutant with the htrA gene restored intracellular survival of the Y. pestis Δlpp mutant. Our results support a role for Lpp in Y. pestis adaptation to the host environment, possibly via transcriptional activation of htrA.

Spaceflight and Simulated Microgravity Increases Virulence of the Known Bacterial Pathogen S. Marcescens

Science.gov (United States)

Clemens-Grisham, Rachel Andrea; Bhattacharya, Sharmila; Wade, William

2016-01-01

After spaceflight, the number of immune cells is reduced in humans. In other research models, including Drosophila, not only is there a reduction in the number of plasmatocytes, but expression of immune-related genes is also changed after spaceflight. These observations suggest that the immune system is compromised after exposure to microgravity. It has also been reported that there is a change in virulence of some bacterial pathogens after spaceflight. We recently observed that samples of gram-negative S. marcescens retrieved from spaceflight is more virulent than ground controls, as determined by reduced survival and increased bacterial growth in the host. We were able to repeat this finding of increased virulence after exposure to simulated microgravity using the rotating wall vessel, a ground based analog to microgravity. With the ground and spaceflight samples, we looked at involvement of the Toll and Imd pathways in the Drosophila host in fighting infection by ground and spaceflight samples. We observed that Imd-pathway mutants were more susceptible to infection by the ground bacterial samples, which aligns with the known role of this pathway in fighting infections by gram-negative bacteria. When the Imd-pathway mutants were infected with the spaceflight sample, however, they exhibited the same susceptibility as seen with the ground control bacteria. Interestingly, all mutant flies show the same susceptibility to the spaceflight bacterial sample as do wild type flies. This suggests that neither humoral immunity pathway is effectively able to counter the increased pathogenicity of the space-flown S. marcescens bacteria.

Masking Responses to Light in Period Mutant Mice

Science.gov (United States)

Pendergast, Julie S.; Yamazaki, Shin

2013-01-01

Masking is an acute effect of an external signal on an overt rhythm and is distinct from the process of entrainment. In the current study, we investigated the phase dependence and molecular mechanisms regulating masking effects of light pulses on spontaneous locomotor activity in mice. The circadian genes, Period1 (Per1) and Per2, are necessary components of the timekeeping machinery and entrainment by light appears to involve the induction of the expression of Per1 and Per2 mRNAs in the suprachiasmatic nuclei (SCN). We assessed the roles of the Per genes in regulating masking by assessing the effects of light pulses on nocturnal locomotor activity in C57BL/6J Per mutant mice. We found that Per1−/− and Per2−/− mice had robust negative masking responses to light. In addition, the locomotor activity of Per1−/−/Per2−/− mice appeared to be rhythmic in the light-dark (LD) cycle, and the phase of activity onset was advanced (but varied among individual mice) relative to lights off. This rhythm persisted for 1 to 2 days in constant darkness in some Per1−/−/Per2−/− mice. Furthermore, Per1−/−/Per2−/− mice exhibited robust negative masking responses to light. Negative masking was phase dependent in wild-type mice such that maximal suppression was induced by light pulses at zeitgeber time 14 (ZT14) and gradually weaker suppression occurred during light pulses at ZT16 and ZT18. By measuring the phase shifts induced by the masking protocol (light pulses were administered to mice maintained in the LD cycle), we found that the phase responsiveness of Per mutant mice was altered compared to wild-types. Together, our data suggest that negative masking responses to light are robust in Per mutant mice and that the Per1−/−/Per2−/− SCN may be a light-driven, weak/damping oscillator. PMID:21793695

Spatial constraints govern competition of mutant clones in human epidermis.

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Lynch, M D; Lynch, C N S; Craythorne, E; Liakath-Ali, K; Mallipeddi, R; Barker, J N; Watt, F M

2017-10-24

Deep sequencing can detect somatic DNA mutations in tissues permitting inference of clonal relationships. This has been applied to human epidermis, where sun exposure leads to the accumulation of mutations and an increased risk of skin cancer. However, previous studies have yielded conflicting conclusions about the relative importance of positive selection and neutral drift in clonal evolution. Here, we sequenced larger areas of skin than previously, focusing on cancer-prone skin spanning five decades of life. The mutant clones identified were too large to be accounted for solely by neutral drift. Rather, using mathematical modelling and computational lattice-based simulations, we show that observed clone size distributions can be explained by a combination of neutral drift and stochastic nucleation of mutations at the boundary of expanding mutant clones that have a competitive advantage. These findings demonstrate that spatial context and cell competition cooperate to determine the fate of a mutant stem cell.

Meiotic UV-sensitive mutant that causes deletion of duplications in neurospora

International Nuclear Information System (INIS)

Newmeyer, D.; Galeazzi, D.R.

1978-01-01

The meiotic-3 (mei-3) mutant of Neurospora crassa has several effects: (1) when homozygous, it almost completely blocks meiosis and ascospore formation, (2) it is sensitive to uv, (3) its growth is inhibited by histidine, and (4) it increases the instability of nontandem duplications. This was shown for duplications produced by five different rearrangements and was demonstrated by two different criteria. The effects on meiosis and duplication instability are expressed strongly at 25 0 ; the effects on sensitivity to uv and to histidine are expressed strongly at 38.5 0 but only slightly at 25 0 . Nevertheless, all four effects were shown to be due to a single gene. Mei-3 is not allelic with previously reported uv-sensitive mutants. Two other results were obtained that are not necessarily due to mei-3: (1) a cross involving mei-3 produced a new unlinked meiotic mutant, mei-4, which is not sensitive to uv or histidine, and (2) a burst of several new mutants occurred in a different mei-3 stock, including a partial revertant to mei-3. Mei-3 has previously been shown to cause frequent complete loss of a terminal duplicate segment, beginning exactly at the original rearrangement breakpoint. Possible mechanisms are discussed by which a uv-sensitive mutant could cause such precise deletions

Arabidopsis brassinosteroid biosynthetic mutant dwarf7-1 exhibits slower rates of cell division and shoot induction

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Schulz Burkhard

2010-12-01

Full Text Available Abstract Background Plant growth depends on both cell division and cell expansion. Plant hormones, including brassinosteroids (BRs, are central to the control of these two cellular processes. Despite clear evidence that BRs regulate cell elongation, their roles in cell division have remained elusive. Results Here, we report results emphasizing the importance of BRs in cell division. An Arabidopsis BR biosynthetic mutant, dwarf7-1, displayed various characteristics attributable to slower cell division rates. We found that the DWARF4 gene which encodes for an enzyme catalyzing a rate-determining step in the BR biosynthetic pathways, is highly expressed in the actively dividing callus, suggesting that BR biosynthesis is necessary for dividing cells. Furthermore, dwf7-1 showed noticeably slower rates of callus growth and shoot induction relative to wild-type control. Flow cytometric analyses of the nuclei derived from either calli or intact roots revealed that the cell division index, which was represented as the ratio of cells at the G2/M vs. G1 phases, was smaller in dwf7-1 plants. Finally, we found that the expression levels of the genes involved in cell division and shoot induction, such as PROLIFERATING CELL NUCLEAR ANTIGEN2 (PCNA2 and ENHANCER OF SHOOT REGENERATION2 (ESR2, were also lower in dwf7-1 as compared with wild type. Conclusions Taken together, results of callus induction, shoot regeneration, flow cytometry, and semi-quantitative RT-PCR analysis suggest that BRs play important roles in both cell division and cell differentiation in Arabidopsis.

Transgenic mice display hair loss and regrowth overexpressing mutant Hr gene.

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Zhu, Kuicheng; Xu, Cunshuan; Zhang, Jintao; Chen, Yingying; Liu, Mengduan

2017-10-30

Mutations in the hairless (Hr) gene in both mice and humans have been implicated in the development of congenital atrichia, but the role of Hr in skin and hair follicle (HF) biology remains unknown. Here, we established transgenic mice (TG) overexpressing mutant Hr to investigate its specific role in the development of HF. Three transgenic lines were successfully constructed, and two of them (TG3 and TG8) displayed a pattern of hair loss and regrowth with alternation in the expression of HR protein. The mutant Hr gene inhibited the expression of the endogenous gene in transgenic individuals, which led to the development of alopecia. Interestingly, the hair regrew with the increase in the endogenous expression levels resulting from decreased mutant Hr expression. The findings of our study indicate that the changes in the expression of Hr result in hair loss or regrowth.

Commercialization Of Orchid Mutants For Floriculture Industry

International Nuclear Information System (INIS)

Sakinah Ariffin; Zaiton Ahmad

2014-01-01

Orchids are the main contributors to cut flower industry in Malaysia with an existing good market and a huge business potential. Orchid industry has been established in Malaysia since 1960s but only started to develop and expand since 1980s. Continuous development of new orchid varieties is essential to meet customers' demands. Orchid mutagenesis research using gamma irradiation at Malaysian Nuclear Agency has successfully generated a number of new orchid varieties with commercial potentials. Therefore, Nuclear Malaysia has collaborated with an industrial partner, Hexagon Green Sdn Bhd (HGSB), to carry out commercialization research on these mutants under a Technofund project entitled 'Pre-Commercialization of Mutant Orchids for Cut Flowers Industry' from July 2011 to July 2014. Through this collaboration, Dendrobium orchid mutant plants developed by Nuclear Malaysia were transferred to HGSB's commercial orchid nursery at Bukit Changgang Agrotechnology Park, Banting, Selangor, for mass-propagation. The activities include evaluations on plant growth performance, flower quality, post harvest and market potential of these mutants. Mutants with good field performance have been identified and filed for Plant Variety Protection (PVP) with Department of Agriculture Malaysia. This paper describes outputs from this collaboration and activities undertaken in commercializing these mutants. (author)

Specific TP53 Mutants Overrepresented in Ovarian Cancer Impact CNV, TP53 Activity, Responses to Nutlin-3a, and Cell Survival

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Lisa K. Mullany

2015-10-01

Full Text Available Evolutionary Action analyses of The Cancer Gene Atlas data sets show that many specific p53 missense and gain-of-function mutations are selectively overrepresented and functional in high-grade serous ovarian cancer (HGSC. As homozygous alleles, p53 mutants are differentially associated with specific loss of heterozygosity (R273; chromosome 17; copy number variation (R175H; chromosome 9; and up-stream, cancer-related regulatory pathways. The expression of immune-related cytokines was selectively related to p53 status, showing for the first time that specific p53 mutants impact, and are related to, the immune subtype of ovarian cancer. Although the majority (31% of HGSCs exhibit loss of heterozygosity, a significant number (24% maintain a wild-type (WT allele and represent another HGSC subtype that is not well defined. Using human and mouse cell lines, we show that specific p53 mutants differentially alter endogenous WT p53 activity; target gene expression; and responses to nutlin-3a, a small molecular that activates WT p53 leading to apoptosis, providing “proof of principle” that ovarian cancer cells expressing WT and mutant alleles represent a distinct ovarian cancer subtype. We also show that siRNA knock down of endogenous p53 in cells expressing homozygous mutant alleles causes apoptosis, whereas cells expressing WT p53 (or are heterozygous for WT and mutant p53 alleles are highly resistant. Therefore, despite different gene regulatory pathways associated with specific p53 mutants, silencing mutant p53 might be a suitable, powerful, global strategy for blocking ovarian cancer growth in those tumors that rely on mutant p53 functions for survival. Knowing p53 mutational status in HGSC should permit new strategies tailored to control this disease.

Trehalose, glycogen and ethanol metabolism in the gcr1 mutant of Saccharomyces cerevisiae

DEFF Research Database (Denmark)

Seker, Tamay; Hamamci, H.

2003-01-01

Since Gcr1p is pivotal in controlling the transcription of glycolytic enzymes and trehalose metabolism seems to be one of the control points of glycolysis, we examined trehalose and glycogen synthesis in response to 2 % glucose pulse during batch growth in gcr1 (glucose regulation-1) mutant lacking...... fully functional glycolytic pathway and in the wild-type strain. An increase in both trehalose and glycogen stores was observed 1 and 2 h after the pulse followed by a steady decrease in both the wild-type and the gcr1 mutant. The accumulation was faster while the following degradation was slower in gcr......1 cells compared to wild-type ones. Although there was no distinct glucose consumption in the mutant cells it seemed that the glucose repression mechanism is similar in gcr1 mutant and in wild-type strain at least with respect to trehalose and glycogen metabolism....

Evaluation of dwarf mutant of cowpea (Vigna Unguiculata L. Walp.) developed through gamma irradiation for nitrogen fixation characters

International Nuclear Information System (INIS)

Anjana, G.; Thimmaiah, S.K.

2002-01-01

A dwarf mutant developed through gamma-irradiation and mutation breeding of its parent cowpea variety, namely KBC-1 has been characterized for nitrogen-fixation characters such as root nodule acetylene reduction activity (ARA) and legthemoglobin content at different days after sowing (DAS). Significant variations in these characters were noticed among the varieties and for interactions between the varieties and DAS. The ARA was nearly one-and-a half fold higher in the mutant at both 30 (12.69 μmoles)C 2 H 4 formed/h/g fr.wt. of nodules) and 50 DAS (6.74 μmoles) over its parent (9.20 and 4.46 μmoles at 30 and 50 DAS, respectively). Further, the ARA in the mutant decreased linearly with an increase in the DAS. The leghemoglobin (Lb) content was also higher in the mutant over the parent at all the DAS. However, it decreased linearly with an increase in the DAS in both the mutant and the parent. The highest leghemoglobin content was noticed at 30 DAS in both mutant (2.1 mg/g fr. wt. of nodules) and the parent (1.45 mg/g). Thus, the dwarf cowpea mutant was found to be associated with higher nitrogen-fixing ability which could be exploited in future breeding programmes. (author)

Rescuing mutant CFTR: a multi-task approach to a better outcome in treating cystic fibrosis.

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Amaral, Margarida D; Farinha, Carlos M

2013-01-01

Correcting multiple defects of mutant CFTR with small molecule compounds has been the goal of an increasing number of recent Cystic Fibrosis (CF) drug discovery programmes. However, the mechanism of action (MoA) by which these molecules restore mutant CFTR is still poorly understood, in particular of CFTR correctors, i.e., compounds rescuing to the cells surface the most prevalent mutant in CF patients--F508del-CFTR. However, there is increasing evidence that to fully restore the multiple defects associated with F508del-CFTR, different small molecules with distinct corrective properties may be required. Towards this goal, a better insight into MoA of correctors is needed and several constraints should be addressed. The methodological approaches to achieve this include: 1) testing the combined effect of compounds with that of other (non-pharmacological) rescuing strategies (e.g., revertants or low temperature); 2) assessing effects in multiple cellular models (non-epithelial vs epithelial, non-human vs human, immortalized vs primary cultures, polarized vs non polarized, cells vs tissues); 3) assessing compound effects on isolated CFTR domains (e.g., compound binding by surface plasmon resonance, assessing effects on domain folding and aggregation); and finally 4) assessing compounds specificity in rescuing different CFTR mutants and other mutant proteins. These topics are reviewed and discussed here so as to provide a state-of-the art review on how to combine multiple ways of rescuing mutant CFTR to the ultimate benefit of CF patients.

GPNMB ameliorates mutant TDP-43-induced motor neuron cell death.

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Nagahara, Yuki; Shimazawa, Masamitsu; Ohuchi, Kazuki; Ito, Junko; Takahashi, Hitoshi; Tsuruma, Kazuhiro; Kakita, Akiyoshi; Hara, Hideaki

2017-08-01

Glycoprotein nonmetastatic melanoma protein B (GPNMB) aggregates are observed in the spinal cord of amyotrophic lateral sclerosis (ALS) patients, but the detailed localization is still unclear. Mutations of transactive response DNA binding protein 43kDa (TDP-43) are associated with neurodegenerative diseases including ALS. In this study, we evaluated the localization of GPNMB aggregates in the spinal cord of ALS patients and the effect of GPNMB against mutant TDP-43 induced motor neuron cell death. GPNMB aggregates were not localized in the glial fibrillary acidic protein (GFAP)-positive astrocyte and ionized calcium binding adaptor molecule-1 (Iba1)-positive microglia. GPNMB aggregates were localized in the microtubule-associated protein 2 (MAP-2)-positive neuron and neurofilament H non-phosphorylated (SMI-32)-positive neuron, and these were co-localized with TDP-43 aggregates in the spinal cord of ALS patients. Mock or TDP-43 (WT, M337V, and A315T) plasmids were transfected into mouse motor neuron cells (NSC34). The expression level of GPNMB was increased by transfection of mutant TDP-43 plasmids. Recombinant GPNMB ameliorated motor neuron cell death induced by transfection of mutant TDP-43 plasmids and serum-free stress. Furthermore, the expression of phosphorylated ERK1/2 and phosphorylated Akt were decreased by this stress, and these expressions were increased by recombinant GPNMB. These results indicate that GPNMB has protective effects against mutant TDP-43 stress via activating the ERK1/2 and Akt pathways, and GPNMB may be a therapeutic target for TDP-43 proteinopathy in familial and sporadic ALS. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

GH and IGF1: roles in energy metabolism of long-living GH mutant mice.

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Brown-Borg, Holly M; Bartke, Andrzej

2012-06-01

Of the multiple theories to explain exceptional longevity, the most robust of these has centered on the reduction of three anabolic protein hormones, growth hormone (GH), insulin-like growth factor, and insulin. GH mutant mice live 50% longer and exhibit significant differences in several aspects of energy metabolism as compared with wild-type mice. Mitochondrial metabolism is upregulated in the absence of GH, whereas in GH transgenic mice and dwarf mice treated with GH, multiple aspects of these pathways are suppressed. Core body temperature is markedly lower in dwarf mice, yet whole-body metabolism, as measured by indirect calorimetry, is surprisingly higher in Ames dwarf and Ghr-/- mice compared with normal controls. Elevated adiponectin, a key antiinflammatory cytokine, is also very likely to contribute to longevity in these mice. Thus, several important components related to energy metabolism are altered in GH mutant mice, and these differences are likely critical in aging processes and life-span extension.

Population genetics inference for longitudinally-sampled mutants under strong selection.

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Lacerda, Miguel; Seoighe, Cathal

2014-11-01

Longitudinal allele frequency data are becoming increasingly prevalent. Such samples permit statistical inference of the population genetics parameters that influence the fate of mutant variants. To infer these parameters by maximum likelihood, the mutant frequency is often assumed to evolve according to the Wright-Fisher model. For computational reasons, this discrete model is commonly approximated by a diffusion process that requires the assumption that the forces of natural selection and mutation are weak. This assumption is not always appropriate. For example, mutations that impart drug resistance in pathogens may evolve under strong selective pressure. Here, we present an alternative approximation to the mutant-frequency distribution that does not make any assumptions about the magnitude of selection or mutation and is much more computationally efficient than the standard diffusion approximation. Simulation studies are used to compare the performance of our method to that of the Wright-Fisher and Gaussian diffusion approximations. For large populations, our method is found to provide a much better approximation to the mutant-frequency distribution when selection is strong, while all three methods perform comparably when selection is weak. Importantly, maximum-likelihood estimates of the selection coefficient are severely attenuated when selection is strong under the two diffusion models, but not when our method is used. This is further demonstrated with an application to mutant-frequency data from an experimental study of bacteriophage evolution. We therefore recommend our method for estimating the selection coefficient when the effective population size is too large to utilize the discrete Wright-Fisher model. Copyright © 2014 by the Genetics Society of America.

Loss of circadian clock accelerates aging in neurodegeneration-prone mutants.

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Krishnan, Natraj; Rakshit, Kuntol; Chow, Eileen S; Wentzell, Jill S; Kretzschmar, Doris; Giebultowicz, Jadwiga M

2012-03-01

Circadian clocks generate rhythms in molecular, cellular, physiological, and behavioral processes. Recent studies suggest that disruption of the clock mechanism accelerates organismal senescence and age-related pathologies in mammals. Impaired circadian rhythms are observed in many neurological diseases; however, it is not clear whether loss of rhythms is the cause or result of neurodegeneration, or both. To address this important question, we examined the effects of circadian disruption in Drosophila melanogaster mutants that display clock-unrelated neurodegenerative phenotypes. We combined a null mutation in the clock gene period (per(01)) that abolishes circadian rhythms, with a hypomorphic mutation in the carbonyl reductase gene sniffer (sni(1)), which displays oxidative stress induced neurodegeneration. We report that disruption of circadian rhythms in sni(1) mutants significantly reduces their lifespan compared to single mutants. Shortened lifespan in double mutants was coupled with accelerated neuronal degeneration evidenced by vacuolization in the adult brain. In addition, per(01)sni(1) flies showed drastically impaired vertical mobility and increased accumulation of carbonylated proteins compared to age-matched single mutant flies. Loss of per function does not affect sni mRNA expression, suggesting that these genes act via independent pathways producing additive effects. Finally, we show that per(01) mutation accelerates the onset of brain pathologies when combined with neurodegeneration-prone mutation in another gene, swiss cheese (sws(1)), which does not operate through the oxidative stress pathway. Taken together, our data suggest that the period gene may be causally involved in neuroprotective pathways in aging Drosophila. Copyright © 2011 Elsevier Inc. All rights reserved.

The Effect of Vitamin E on the Survival Rate of unc-13 Caenorhabditis elegans mutants under Oxidative Stress

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Jessica Porcelan

2012-01-01

Full Text Available Caenorhabditis elegans unc-13 mutants express decreased neuronal activity and thus are a good model strain for examining defective nervous systems. These unc-13 mutants as well as wild type N2 strains, show rapid mortality when under oxidative stress. However, the antioxidant vitamin E may prolong survival in unc-13 mutant and N2 strains under oxidative stress. The addition of vitamin E to organisms under oxidative stress has a protective effect in both N2 and unc-13 C. elegans strains. Interestingly, vitamin E resulted in a greater increase in survival rate in N2 worms than with unc-13 mutant worms. While both strains displayed lower mortality rates with the addition of vitamin E, this finding suggests that vitamin E more efficiently increases survival rates of C. elegans with typical nervous system function. The efficacy of vitamin E implies that use of antioxidants may lessen the damage caused by oxidative stress in both N2 and mutant worms.

Posaconazole exhibits in vitro and in vivo synergistic antifungal activity with caspofungin or FK506 against Candida albicans.

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Ying-Lien Chen

Full Text Available The object of this study was to test whether posaconazole, a broad-spectrum antifungal agent inhibiting ergosterol biosynthesis, exhibits synergy with the β-1,3 glucan synthase inhibitor caspofungin or the calcineurin inhibitor FK506 against the human fungal pathogen Candida albicans. Although current drug treatments for Candida infection are often efficacious, the available antifungal armamentarium may not be keeping pace with the increasing incidence of drug resistant strains. The development of drug combinations or novel antifungal drugs to address emerging drug resistance is therefore of general importance. Combination drug therapies are employed to treat patients with HIV, cancer, or tuberculosis, and has considerable promise in the treatment of fungal infections like cryptococcal meningitis and C. albicans infections. Our studies reported here demonstrate that posaconazole exhibits in vitro synergy with caspofungin or FK506 against drug susceptible or resistant C. albicans strains. Furthermore, these combinations also show in vivo synergy against C. albicans strain SC5314 and its derived echinocandin-resistant mutants, which harbor an S645Y mutation in the CaFks1 β-1,3 glucan synthase drug target, suggesting potential therapeutic applicability for these combinations in the future.

Mice lacking the kf-1 gene exhibit increased anxiety- but not despair-like behavior

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Atsushi Tsujimura

2008-09-01

Full Text Available KF-1 was originally identified as a protein encoded by human gene with increased expression in the cerebral cortex of a patient with Alzheimer’s disease. In mouse brain, kf-1 mRNA is detected predominantly in the hippocampus and cerebellum, and kf-1 gene expression is elevated also in the frontal cortex of rats after chronic antidepressant treatments. KF-1 mediates E2-dependent ubiquitination and may modulate cellular protein levels as an E3 ubiquitin ligase, though its target proteins are not yet identified. To elucidate the role of kf-1 in the central nervous system, we generated kf-1 knockout mice by gene targeting, using Cre-lox recombination. The resulting kf-1−/− mice were normal and healthy in appearance. Behavioral analyses revealed that kf-1−/− mice showed significantly increased anxiety-like behavior compared with kf-1+/+ littermates in the light/dark transition and elevated plus maze tests; however, no significant differences were observed in exploratory locomotion using the open field test or in behavioral despair using the forced swim and tail suspension tests. These observations suggest that KF-1 suppresses selectively anxiety under physiological conditions probably through modulating protein levels of its unknown target(s. Interestingly, kf-1−/− mice exhibited significantly increased prepulse inhibition, which is usually reduced in human schizophrenic patients. Thus, the kf-1−/− mice provide a novel animal model for elucidating molecular mechanisms of psychiatric diseases such as anxiety/depression, and may be useful for screening novel anxiolytic/antidepressant compounds.

Mycothiol-Deficient Mycobacterium smegmatis Mutants Are Hypersensitive to Alkylating Agents, Free Radicals, and Antibiotics

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Rawat, Mamta; Newton, Gerald L.; Ko, Mary; Martinez, Gladys J.; Fahey, Robert C.; Av-Gay, Yossef

2002-01-01

Mycothiol (MSH; 1d-myo-inosityl 2-[N-acetyl-l-cysteinyl]amido-2-deoxy-α-d-glucopyranoside) is the major low-molecular-weight thiol produced by mycobacteria. Mutants of Mycobacterium smegmatis mc2155 deficient in MSH production were produced by chemical mutagenesis as well as by transposon mutagenesis. One chemical mutant (mutant I64) and two transposon mutants (mutants Tn1 and Tn2) stably deficient in MSH production were isolated by screening for reduced levels of MSH content. The MSH contents of transposon mutants Tn1 and Tn2 were found to be less than 0.1% that of the parent strain, and the MSH content of I64 was found to be 1 to 5% that of the parent strain. All three strains accumulated 1d-myo-inosityl 2-deoxy-α-d-glucopyranoside to levels 20- to 25-fold the level found in the parent strain. The cysteine:1d-myo-inosityl 2-amino-2-deoxy-α-d-glucopyranoside ligase (MshC) activities of the three mutant strains were ≤2% that of the parent strain. Phenotypic analysis revealed that these MSH-deficient mutants possess increased susceptibilities to free radicals and alkylating agents and to a wide range of antibiotics including erythromycin, azithromycin, vancomycin, penicillin G, rifamycin, and rifampin. Conversely, the mutants possess at least 200-fold higher levels of resistance to isoniazid than the wild type. We mapped the mutation in the chemical mutant by sequencing the mshC gene and showed that a single amino acid substitution (L205P) is responsible for reduced MSH production and its associated phenotype. Our results demonstrate that there is a direct correlation between MSH depletion and enhanced sensitivity to toxins and antibiotics. PMID:12384335

A metabolic signature for long life in the Caenorhabditis elegans Mit mutants.

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Butler, Jeffrey A; Mishur, Robert J; Bhaskaran, Shylesh; Rea, Shane L

2013-02-01

Mit mutations that disrupt function of the mitochondrial electron transport chain can, inexplicably, prolong Caenorhabditis elegans lifespan. In this study we use a metabolomics approach to identify an ensemble of mitochondrial-derived α-ketoacids and α-hydroxyacids that are produced by long-lived Mit mutants but not by other long-lived mutants or by short-lived mitochondrial mutants. We show that accumulation of these compounds is dependent on concerted inhibition of three α-ketoacid dehydrogenases that share dihydrolipoamide dehydrogenase (DLD) as a common subunit, a protein previously linked in humans with increased risk of Alzheimer's disease. When the expression of DLD in wild-type animals was reduced using RNA interference we observed an unprecedented effect on lifespan - as RNAi dosage was increased lifespan was significantly shortened, but, at higher doses, it was significantly lengthened, suggesting that DLD plays a unique role in modulating length of life. Our findings provide novel insight into the origin of the Mit phenotype. © 2012 The Authors Aging Cell © 2012 Blackwell Publishing Ltd/Anatomical Society of Great Britain and Ireland.

Brucella abortus mutants lacking ATP-binding cassette transporter proteins are highly attenuated in virulence and confer protective immunity against virulent B. abortus challenge in BALB/c mice.

Science.gov (United States)

Truong, Quang Lam; Cho, Youngjae; Park, Soyeon; Park, Bo-Kyoung; Hahn, Tae-Wook

2016-06-01

Brucella abortus RB51 is an attenuated vaccine strain that has been most frequently used for bovine brucellosis. Although it is known to provide good protection in cattle, it still has some drawbacks including resistance to rifampicin, residual virulence and pathogenicity in humans. Thus, there has been a continuous interest on new safe and effective bovine vaccine candidates. In the present study, we have constructed unmarked mutants by deleting singly cydD and cydC genes, which encode ATP-binding cassette transporter proteins, from the chromosome of the virulent Brucella abortus isolate from Korean cow (referred to as IVK15). Both IVK15ΔcydD and ΔcydC mutants showed increased sensitivity to metal ions, hydrogen peroxide and acidic pH, which are mimic to intracellular environment during host infection. Additionally, the mutants exhibited a significant growth defect in RAW264.7 cells and greatly attenuated in mice. Vaccination of mice with either IVK15ΔcydC or IVK15ΔcydD mutant could elicit an anti-Brucella specific immunoglobulin G (IgG) and IgG subclass responses as well as enhance the secretion of interferon-gamma, and provided better protection against challenge with B. abortus strain 2308 than with the commercial B. abortus strain RB51 vaccine. Collectively, these results suggest that both IVK15ΔcydC and IVK15ΔcydD mutants could be an attenuated vaccine candidate against B. abortus. Copyright © 2016 Elsevier Ltd. All rights reserved.

Agrobacterium tumefaciens T-DNA Integration and Gene Targeting in Arabidopsis thaliana Non-Homologous End-Joining Mutants