Parallelism and paradoxes on viability and the life span of two loss-of-function mutations: Heat shock protein transcriptional regulator hsf1 and l(2)gl tumor suppressor in Drosophila melanogaster

In this study we analyzed how a dosage decrease in mono- and diheterozygotes on both lethal alleles of the lgl-gene and hsf heat shock regulator influences viability and life span at optimal and high temperature 29°C conditions. We found that hsf ¹/+ (1 dosage of active hsf -factor) heterozygote animals had significantly increased viability (up to 30–39%) in case of its development from egg to imago under the stress of 29°C. However, this stress-protective effect of a decreased dosage of HSF1 was suppressed in diheterozygotes, while the dosage of tumor suppressor lgl was simultaneously decreased. Under stress temperature conditions, a decrease in dosage of one of the alleles also increased the average life span and delayed aging, especially in the case of maternal inheritance of each of the loss-of-function mutations. In diheterozygotes the average life span had intermediate meanings. However, in diheterozygote males under stress conditions the positive longevity effect of hsf was suppressed in the presence of the lgl-mutation. Paradoxically, that decrease of expression of each of the studied vital genes provided a positive effect on both viability and life span under stress conditions. However, a simultaneous dosage decrease of two loss-of-function alleles in diheterozygotes resulted in disbalanced effects on the organism level. The received data indicate interaction between HSF1 and LGL gene products during ontogenesis and stress-defending processes.     

Polymorphisms in major histocompatibility complex class IIα genes are associated with resistance to infectious hematopoietic necrosis in rainbow trout,Oncorhynchus mykiss (Walbaum, 1792)

Infectious hematopoietic necrosis is a serious viral disease of salmonids, including rainbow trout Oncorhynchus mykiss, and causes tremendous economic losses to the rainbow trout farming industry. Major histocompatibility complex (MHC) genes are crucial elements of adaptive immunity in vertebrate organisms and have been linked with the resistance to numerous pathogenic diseases. In this study, polymerase chain reaction‐single strand conformation polymorphism (PCR‐SSCP) followed by cloning and sequencing were used to examine polymorphisms in the DAA genes (specifically DAA exon 2 of MHC class IIα) of rainbow trout and investigate their association with the infectious hematopoietic necrosis virus (IHNV) resistance in rainbow trout. Seventeen alleles were resolved, including 13 novel alleles. Individuals possessed between two and five alleles, indicating that the genome harbours at least three closely‐related DAA exon 2 loci. The ratio of non‐synonymous to synonymous nucleotide substitutions suggested that DAA exon 2 is under positive selection. A greater variability of amino acids and non‐synonymous nucleotide substitution rate was evident in the peptide‐binding region (PBR) than in the non‐PBR (27.75%). Importantly, the analyses revealed that certain MHC class IIα alleles appear to confer resistance to IHNV in rainbow trout, while others confer susceptibility. The most common alleles in the resistant populations of rainbow trout, Onmy‐DAA*1301 and Onmy‐DAA*0304, confer resistance to IHNV and were not present in the susceptible population. Hence, these alleles may be ideal molecular markers that can assist the breeding of IHNV resistance in rainbow trout.     

Detection of isoimmune antibodies against a population of human B-lymphocytes]

Rosette-forming ability of human lymphocytes was tested before and after their sensitization with isoimmune sera against histocompatibility antigens. Anti-HLA sera inhibited the ability of T- and B- lymphocyteè to form rosettes. Some sera inhibited rosette formation mostly of B-lymphocytes; they also possessed marked capacity to react with B-lymphocytes population in prolonged lymphotoxic tests.     

Allelic sequence polymorphisms in the intron region of the nuclear-encoded GapC gene preceded the speciation of three closely related Abies species (Pinaceae)

The DNA sequences of GapC intron 8 were determined for three closely related Abies species, Abies firma, Abies homolepis and Abies veitchii, and ten alleles were identified. Although, in most cases, an allele was specifically detected in one species, some rare alleles were found in two species. The phylogenetic analysis of those alleles showed that they trace back to different ancestral sequences, and that a species possessed the different originated alleles. The polymorphism of the GapC gene observed in the three Abies species seemed to have preceded their evolutionary divergence. Received: 1 February 2000 / Accepted: 10 May 2000     

Isozyme gene markers in Vicia faba L.

Summary This study was conducted to assess the genetic basis of the variability observed for the glutamate oxaloacetate transaminase (GOT), Superoxide dismutase (SOD), esterase (EST), and malate dehydrogenase (MDH) isozyme systems in different open-pollinated Vicia faba varieties. Individual plants showing contrasting zymogram patterns were simultaneously selfed and cross-combined. Crossing was unsuccessful in producing progeny, and only selfed progenies were suitable for genetical analysis of isozyme variability. Three zones of GOT activity were made visible. The isozyme of GOT-2 and GOT-3 zones were dimeric and under the control of three alleles at the Got-2 locus and two alleles at the Got-3 locus, respectively. The isozymes of the GOT-1 zone did not show any variability. Three zones of SOD isozyme activity were made visible. The isozymes occurring in the SOD-1 (chloroplastic isozyme form) and SOD-2 (cytosol isozyme form) zones were dimeric and under the control of two alleles at the Sod-1 and Sod-2 loci. The isozyme visualized in the SOD-3 zone (mitochondrial isozyme form) were tetrameric and under the control of two alleles at the Sod-3 locus. Apparently the isozymes made visible in the most anodal esterase zones EST-1, EST-2, and EST-3 were monomeric, and the occurrence of two alleles at each of two different loci explained the variability observed in the EST-2 and EST-3 zones. For MDH, only two five-banded zymogram pattern types were found, and every selfed progeny showed only one of the two zymogram type, indicating that each individual possessed fixed alleles at the loci controlling MDH isozyme. Got-2, Got-3, Sod-1, Sod-2, and Sod-3 appear to be five new isozyme gene markers that can be useful in Vicia faba breeding for linkage study, varietal fingerprinting, outcrossing rate estimate, and indirect selection for quantitative characters.     

Evaluation of novel beta-lactam antibiotics in comparison to cefotaxime on plant regeneration of <Emphasis Type="Italic">Citrus sinensis</Emphasis> L. Osb.

Identification of beta-lactam antibiotics that have negligible effects on plant regeneration is a critical step towards the establishment of a reliable Agrobacterium-mediated transformation protocol for perennial trees. In the present report, we have evaluated the effects of the novel beta-lactam antibiotics meropenem and timentin on plant regeneration of a perennial woody fruit plant, Citrus sinensis, in comparison with the commonly used beta-lactam cefotaxime. It was observed that, in contrast to cefotaxime, meropenem and timentin had a positive or no detrimental effect on the shoot regeneration from epicotyl explants. Residual effects of the beta-lactams from shoot regeneration medium also affected the subsequent ability of the roots to elongate. The addition of meropenem and/or timentin in the rooting medium mostly improved or did not affect the rooting ability of the adventitious shoots. These data indicated that meropenem and timentin can positively replace cefotaxime in Agrobacterium-mediated transformation of C. sinensis.     

Viability and cellulose synthesizing ability of Gluconacetobacter xylinus cells under high-hydrostatic pressure

The effect of pressure on viability and the synthesis of bacterial cellulose (BC) by Gluconacetobacter xylinus ATCC53582 were investigated. G. xylinus was statically cultivated in a pressurized vessel under 0.1, 30, 60, and 100 MPa at 25°C for 6 days. G. xylinus cells remained viable and retained cellulose producing ability under all the conditions tested, though the production of cellulose decreased with increasing the pressure. The BCs produced at each pressure condition were analyzed by field emission scanning electron microscopy (FE-SEM) and Fourier Transform Infrared (FT-IR). FE-SEM revealed that the widths of BC fibers produced under high pressure decreased as compared with those produced under the atmospheric pressure. By FT-IR, all the BCs were found to be of Cellulose type I, as the same as typical native cellulose. Our findings evidently showed that G. xylinus possessed a piezotolerant (barotolerant) feature adapting to 100 MPa without losing its BC producing ability. This was the first attempt in synthesizing BC with G. xylinus under elevated pressure of 100 MPa, which corresponded to the deep sea at 10,000 m.     

Positive selection pressure on rice blast resistance allele Piz-t makes it divergent in Indian land races

Abstract

Allelic variants of the broad-spectrum blast resistance gene, Piz-t, have been analyzed in 48 rice lines selected after phenotyping across three blast hot-spot regions of India. Single Nucleotide Polymorhisms in the form of transitions were more frequent than the transversions in the alleles. On the basis of nucleotide polymorphism, 46 haplotypes have been identified, with major haplotypes forming three main haplogroups. The Piz-t alleles formed mostly region-specific clusters. Resistant and susceptible Piz-t alleles were grouped into separate sub-clusters. The value of Tajima's D was negative indicating positive selection on Piz-t locus. Sequence variations were more abundant in the leucine rich repeats (LRR) region than in the NB-ARC (nucleotide-binding adaptor shared by APAF-1,R proteins, and CED-4) region, indicating that the LRR region has played a more important role in the evolution of this allele. The detailed molecular analysis of the Piz-t locus provide insights to high degree of inter-and intra-specific relationship among the Indian land races of rice which will help in the selection of better alleles for future rice breeding programs.     

The use of genetic markers in the analysis of competitive interactions in Drosophila melanogaster

A range of long established inbred lines derived from the TEXAS population of Drosophila melanogaster have been used to elucidate the nature of the competitive interactions which occur in genetically heterogeneous mixtures. A prerequisite for this type of investigation is the ability to distinguish the genotypes which compete in mixed culture. Specific marker alleles are generally used to achieve this distinction although in the past little attention has been given to the possibility of competitive bias introduced by the marker alleles themselves. For the experiments reported in this paper two specific marker alleles (y ² and w ^a) have been introduced independently into the TEXAS inbred lines. In this way the original wild type inbred lines could be compared with similar series of genotypes marked with either y ² or w ^a and the effects of the marker alleles determined.The results indicated that the body colour mutation (y ²) was neutral in its effect on the competitive interaction of recipient strains. The introduction of the white apricot eye colour mutation (w ^a) however, had a pronounced and deleterious effect on competitive ability. This effect was to render genotypes less able to compete effectively in mixed culture by depressing inter-genotypic competitive ability. These effects were found to be consistent over a range of genotypes and for each of two characters measuring competitive success.     

Provenance variation in tolerance of Melaleuca cajuputi trees to interactive effects of aluminum and salt

A future rise in sea level will expand areas of salt-affected acid sulfate soil, calling for studies on plant tolerance to combined aluminum (Al) and salt (NaCl) stress. We investigated random amplified polymorphic DNA (RAPD) profiles and tolerance to Al and NaCl alone and in combination in 14 Melaleuca cajuputi Powell provenances. Two-month-old seedlings were grown with or without 10 mM Al and/or 50 mM NaCl at pH 3.8 for 3 months. Plant growth was reduced mostly by combined Al and NaCl stress and then by NaCl and least by Al. Moreover, Al enhanced the effect of NaCl on growth and vice versa. There were significant differences in plant growth among provenances under all treatments; however, positive relationships were found among Al tolerance, NaCl tolerance, and combined Al and NaCl tolerance. Provenance variation in stress tolerance increases with the increasing levels of stress effect. Furthermore, NaCl tolerance tended to have a positive relationship with osmotic potential. Leaf sap K concentration was decreased by NaCl and increased by Al; however, provenances that were more tolerant to NaCl tended to have lower K concentrations. RAPD analysis also revealed genetic variation among provenances. These results suggest that the low tolerance to combined Al and NaCl stress in M. cajuputi is largely due to low tolerance to NaCl and the effect of interaction between Al and NaCl. Provenance variation in stress tolerance was significant and could be partly explained by the variation in genetic material and the ability of plants to reduce ion excess stress in their shoots.     

Cryptic introgression between murre sister species (Uria spp.) in the Pacific low Arctic: frequency, cause, and implications

As southern species undergo northward range expansions, reports of hybridization between temperate and arctic taxa are increasing, which may have important implications for the evolution, conservation, and management of arctic species. The extent of hybridization between temperate common murres (Uria aalge) and arctic thick-billed murres (U. lomvia), seabirds in the family Alcidae, has been the subject of debate. In a previous survey of variation in mitochondrial DNA (mtDNA) in common and thick-billed murres sampled from throughout the North Pacific and low Arctic, 12 of 327 common murres (~4%) were found to possess DNA sequences characteristic of thick-billed murres. In the present study, we surveyed variation in three nuclear introns in 230 common murres and 56 thick-billed murres and report that these putative hybrids carry various combinations of intron alleles from common and thick-billed murres. Analysis using the program STRUCTURE indicated that nine of these individuals possessed high proportions of thick-billed murre intron alleles, two possessed alleles in F1 and F2 proportions, and one individual possessed predominantly common murre intron alleles. We propose that the asymmetric mtDNA introgression we observed is most likely the result of mate choice at mixed colonies based on differences in male mating behaviours. Our results highlight that hybridization between thick-billed and common murres is more prevalent than previously thought, which may have important implications for the conservation and management of arctic-dwelling thick-billed murres as common murres expand northward.     

QTL analysis of flowering time inArabidopsis thaliana

Quantitative trait loci (QTL) analyses based on restriction fragment length polymorphism maps have been used to resolve the genetic control of flowering time in a cross between twoArabidopsis thaliana ecotypes H51 and Landsbergerecta, differing widely in flowering time. Five quantitative trait loci affecting flowering time were identified in this cross (RLN1-5), four of which are located in regions containing mutations or loci previously identified as conferring a late-flowering phenotype. One of these loci is coincident with theFRI locus identified as the major determinant for late flowering and vernalization responsiveness in theArabidopsis ecotype Stockholm.RLN5, which maps to the lower half of chromosome five (between markers mi69 and m233), only affected flowering time significantly under short day conditions following a vernalization period. The late-flowering phenotype of H51 compared to Landsbergerecta was due to alleles conferring late flowering at only two of the five loci. At the three other loci, H51 possessed alleles conferring early flowering in comparison to those of Landsbergerecta. Combinations of alleles conferring early and late flowering from both parents accounted for the transgressive segregation of flowering time observed within the F₂ population. Three QTL,RLN1,RLN2 andRLN3 displayed significant genotype-by-environment interactions for flowering time. A significant interaction between alleles atRLN3 andRLN4 was detected.     

Clonal diversity and genetic differentiation revealed by SSR markers in wild Vaccinium macrocarpon and Vaccinium oxycoccos

American cranberry (Vaccinium macrocarpon) is a perennial, woody plant species, native to North American bogs and wetlands. Cranberries represent one of the few agriculturally important native plants in which wild gene pools are still readily available within the undeveloped wetlands of the northern US and Canada. Earlier studies have reported low genetic variation in V. macrocarpon at the species and population level. However, in this study, we characterised 229 individuals of wild V. macrocarpon and V. oxycoccos (small cranberry) from Wisconsin and 22 accessions using microsatellite markers and observed substantial genetic variation and differentiation within and among populations and species. While V. macrocarpon was analysed using 108 alleles from 11 microsatellite loci revealing 42 unique genotypes, V. oxycoccos was analysed using 156 alleles from eight loci revealing 28 unique genotypes. There were a total of 182 alleles found in both species combined with 156 of those alleles present in V. oxycoccos and 84 alleles found in V. macrocarpon. All eight loci possessed species‐specific alleles with V. oxycoccos possessing 98 private alleles versus 26 private alleles found V. macrocarpon, and 58 alleles were found in common between both species. Our data will be valuable not only for future wild cranberry diversity and population genetics research, but for other cranberry breeding and genetics studies.     

基于基因与抗菌活性筛选的菌株FIM060022多相鉴定

利用PKS-NRPS基因筛选与抗菌活性测定,选取筛选结果为阳性以及广谱抗菌的FIM060022菌株进行多相分类鉴定。结果显示,该菌株对大肠埃希菌(E. coli)、金黄色葡萄球菌(S. aureus)、枯草芽胞杆菌等细菌(B. subtilis),以及白色念珠菌(C. albicans)、红酵母(R. rula)与新型隐球菌(C. neoformans)等真菌具有抗菌活性。通过对菌株的培养特征、形态观察、生化特性、细胞壁组成分析、脂肪酸组成分析、G+C mol%含量组成,结合16S r DNA序列以及PKS/NRPS基因序列分析,将菌株FIM060022鉴定为小单胞菌科疣孢菌属。结果提示FIM060022是一株具有广谱抗菌活性的海洋稀有放线菌,具有产药用化合物的潜能。     

Purine nucleoside phosphorylase polymorphism in the genus Littorina (Prosobranchia: Mollusca)

Examination of eight Atlantic species of the genus Littorina by starch gel electrophoresis of purine nucleoside phosphorylase revealed extensive polymorphism within the L. saxatilis complex. In this group, four alleles have been identified. Heterozygotes are four banded, and thus, as in vertebrates, the enzyme is likely to be a trimer. Breeding experiments confirmed the genetic interpretation of the phenotype patterns. Where species of the saxatilis complex [L. saxatilis (=L. rudis), L. arcana, L. nigrolineata, L. neglecta] are sympatric, there are sometimes significant allele frequency differences between them. A fifth allele was present at a high frequency in L. obtusata and L. mariae, and L. littorea and L. neritoides each possessed unique alleles. A total of eight alleles was identified. Densitometric scanning of heterozygote patterns pointed to activity differences between alleles and also showed that, while the heterotrimeric bands were never less intense than the homotrimeric bands, the heterotrimeric bands were sometimes less intense than expected. It is not clear whether this represents nonrandom association of subunits, decreased stability of heterotrimers, or simply an artifact of the staining and quantifying process.This work was supported by NERC Grant GR3/5319.     

Analysis of the Polymorphic Markers within the CFTR Gene in Cystic Fibrosis Patients and Healthy Donors from Bashkortostan

The differences in the polymorphic allele frequency distribution patterns of the biallelic (M470V and TUB20) and microsatellite (IVS6aGATT, IVS8CA, and IVS17CA) markers within the CFTR gene between normal and delF508 chromosomes have been established. For most of the marker loci similar distribution of the allele frequencies on normal and mutant chromosomes without delF508 was demonstrated. Certain polymorphic alleles displayed substantial linkage disequilibrium with the delF508 mutation. Analysis of the IVS6aGATT-IVS8CA-M470V-IVS17CA-TUB20 haplotypes association on normal and mutant chromosomes provided identification of the delF508 ancestral haplotype. It was suggested that delF508 mutant chromosomes were introduced into the modern Bashkir gene pool as a result of Slavic migrations from the Eastern Europe. The IVS6aGATT-IVS8CA-M470V-IVS17CA-TUB20major haplotype (77272) revealed was statistically significantly most frequently found on the mutant chromosomes without the delF508 mutation. This finding suggests that the Bashkir cystic fibrosis patients, mostly belonging to the Turkic-speaking families, possessed specific CFTR gene defect associated with the given haplotype.     

Major histocompatibility complex class II genetic variation in forest musk deer (Moschus berezovskii) in China

The major histocompatibility complex (MHC) plays an important role in the immune system of vertebrates. We used the second exon of four MHC class II genes (DRA, DQA1, DQA2 and DRB3) to assess the overall MHC variation in forest musk deer (Moschus berezovskii). We also compared the MHC variation in captive and wild populations. We observed 22 alleles at four loci (four at DRA, four at DQA1, four at DQA2 and 10 at DRB3), 15 of which were newly identified alleles. Results suggest that forest musk deer maintain relatively high MHC variation, which may result from balancing selection. Moreover, considerable diversity was observed at the DRA locus. We found a high frequency of Mobe‐DRA*02, Mobe‐DQA1*01 and Mobe‐DQA2*05 alleles, which may be important for pathogen resistance. A Ewens–Watterson test showed that the DRB3 locus in the wild population had experienced recent balancing selection. We detected a small divergence at the DRA locus, suggesting the effect of weak positive selection on the DRA gene. Alternatively, this locus may be young and not yet adapted a wide spectrum of alleles for pathogen resistance. The significant heterozygosity deficit observed at the DQA1 and DRB3 loci in the captive population and at all four loci in the wild population may be the result of a population bottleneck. Additionally, MHC genetic diversity was higher in the wild population than in the captive, suggesting that the wild population may have the ability to respond to a wider range of pathogens.     

Analysis of genetic control of maize response in anther culture within a diallelic set

The androgenic ability in anther culture in vitro was examined within a diallel set of five maize lines. The complex analysis of genetic variation components, Hayman's diagram, and genetic parameters showed that the anther response is under the control of an additive-dominant genetic system. The examined lines possessed the different correlation of dominant and recessive alleles controlling androgenesis. And 44 was the line with the biggest number of recessive genes, which determined the increase in the trait. The level of dominance varied in different loci, though in the whole the degree of dominance approached to the complete one.