A molecular basis for natural selection at the timeless locus in Drosophila melanogaster

Diapause is a protective response to unfavorable environments that results in a suspension of insect development and is most often associated with the onset of winter. The ls-tim mutation in the Drosophila melanogaster clock gene timeless has spread in Europe over the past 10,000 years, possibly because it enhances diapause. We show that the mutant allele attenuates the photosensitivity of the circadian clock and causes decreased dimerization of the mutant TIMELESS protein isoform to CRYPTOCHROME, the circadian photoreceptor. This interaction results in a more stable TIMELESS product. These findings reveal a molecular link between diapause and circadian photoreception.     

Evidence for a one-allele assortative mating locus

Theoretical models have shown that speciation with gene flow can occur readily via a "one-allele mechanism," where the spread of the same allele within both of two diverging species reduces their subsequent hybridization. Here we present direct genetic evidence for such an allele in Drosophila pseudoobscura. Alleles conferring high or low assortative mating in D. pseudoobscura produce the same effects when inserted into D. persimilis. This observation suggests that the type of genetic variation that is most conducive to controversial modes of speciation with gene flow, such as reinforcement or sympatric speciation, is present in nature.     

Study on the selection of a new chestnut variety-

通过选优和对比分析,选育出了板栗新品种“豫栗王”．经与“信阳大板栗”和“豫罗红”对比试验,结果表明,“豫栗王”具有丰产性强、品质优良、抗病虫等明显的优良性状,是豫南地区值得大面积推广的优良品种．     

Darwinian evolution can follow only very few mutational paths to fitter proteins

Five point mutations in a particular beta-lactamase allele jointly increase bacterial resistance to a clinically important antibiotic by a factor of approximately 100,000. In principle, evolution to this high-resistance beta-lactamase might follow any of the 120 mutational trajectories linking these alleles. However, we demonstrate that 102 trajectories are inaccessible to Darwinian selection and that many of the remaining trajectories have negligible probabilities of realization, because four of these five mutations fail to increase drug resistance in some combinations. Pervasive biophysical pleiotropy within the beta-lactamase seems to be responsible, and because such pleiotropy appears to be a general property of missense mutations, we conclude that much protein evolution will be similarly constrained. This implies that the protein tape of life may be largely reproducible and even predictable.     

Evolutionarily assembled cis-regulatory module at a human ciliopathy locus

Neighboring genes are often coordinately expressed within cis-regulatory modules, but evidence that nonparalogous genes share functions in mammals is lacking. Here, we report that mutation of either TMEM138 or TMEM216 causes a phenotypically indistinguishable human ciliopathy, Joubert syndrome. Despite a lack of sequence homology, the genes are aligned in a head-to-tail configuration and joined by chromosomal rearrangement at the amphibian-to-reptile evolutionary transition. Expression of the two genes is mediated by a conserved regulatory element in the noncoding intergenic region. Coordinated expression is important for their interdependent cellular role in vesicular transport to primary cilia. Hence, during vertebrate evolution of genes involved in ciliogenesis, nonparalogous genes were arranged to a functional gene cluster with shared regulatory elements.     

Characterization of a common susceptibility locus for asthma-related traits

Susceptibility to asthma depends on variation at an unknown number of genetic loci. To identify susceptibility genes on chromosome 7p, we adopted a hierarchical genotyping design, leading to the identification of a 133-kilobase risk-conferring segment containing two genes. One of these coded for an orphan G protein-coupled receptor named GPRA (G protein-coupled receptor for asthma susceptibility), which showed distinct distribution of protein isoforms between bronchial biopsies from healthy and asthmatic individuals. In three cohorts from Finland and Canada, single nucleotide polymorphism-tagged haplotypes associated with high serum immunoglobulin E or asthma. The murine ortholog of GPRA was up-regulated in a mouse model of ovalbumin-induced inflammation. Together, these data implicate GPRA in the pathogenesis of atopy and asthma.     

No major schizophrenia locus detected on chromosome 1q in a large multicenter sample

Reports of substantial evidence for genetic linkage of schizophrenia to chromosome 1q were evaluated by genotyping 16 DNA markers across 107 centimorgans of this chromosome in a multicenter sample of 779 informative schizophrenia pedigrees. No significant evidence was observed for such linkage, nor for heterogeneity in allele sharing among the eight individual samples. Separate analyses of European-origin families, recessive models of inheritance, and families with larger numbers of affected cases also failed to produce significant evidence for linkage. If schizophrenia susceptibility genes are present on chromosome 1q, their population-wide genetic effects are likely to be small.     

Allometric engineering: a causal analysis of natural selection on offspring size

Techniques of offspring size manipulation, "allometric engineering," were used in combination with studies of natural selection to elucidate the causal relation between egg size and offspring survival of lizards. The results experimentally validate premises underlying theories of optimal egg size: fecundity selection favoring the production of large clutches of small eggs was balanced by survival selection favoring large offspring. However, large hatchlings did not always have the highest survival, contrary to most theoretical expectations. Optimizing selection on offspring size per se was the most common pattern. Moreover, matches between average and optimal egg size were qualitative, not quantitative, perhaps reflecting known functional constraints on the production of large eggs.     

Multiple divergent selection on viscosity of a water extract of winter rye

Results of ten cycles of divergent selection on water extract viscosity (WEV) based on varieties of winter rye Al’fa and Moskovskaya 12 are presented. Efficiency of selection depended both on genotype of a variety and direction of selection. Selection in a plus-direction was more effective than in a minus-direction. After ten cycles of selection, the potential of WEV increased in high viscosity populations by 3.3–6.0 times, while it decreased by 2.6–3.5 times in low viscosity populations. The asymmetry of the response was detected during the first cycle of the selection and it remained in all subsequent cycles. The high viscosity populations were more yielding (by 23.8%) than low viscosity populations and had the best baking qualities of grain. Their superiority manifested the most strongly by grain unit (by 7.9%), weight of 1000 grains (by 23.4%), falling number (by 90 s), amylogram height (by 5.4 times), and gelatinization temperature of starch (by 3.2°С). From low viscosity populations, strongly blurring bread with large pores and sticky and restive crumb was produced. Prospects of selection of baking and fodder varieties of a winter rye based on selection of genotypes with high and low WEV are discussed.     

Susceptibility locus for Alzheimer's disease on chromosome 10

The apolipoprotein E (APOE) gene is the only genetic risk factor that has so far been linked to risk for late-onset Alzheimer's disease (LOAD). However, 50 percent of Alzheimer's disease cases do not carry an APOE4 allele, suggesting that other risk factors must exist. We performed a two-stage genome-wide screen in sibling pairs with LOAD to detect other susceptibility loci. Here we report evidence for an Alzheimer's disease locus on chromosome 10. Our stage one multipoint lod score (logarithm of the odds ratio for linkage/no linkage) of 2.48 (266 sibling pairs) increased to 3.83 in stage 2 (429 sibling pairs) close to D10S1225 (79 centimorgans). This locus modifies risk for Alzheimer's disease independent of APOE genotype.     

草坪草引种筛选试验研究

3年的试验表明：草地早熟禾可作为类似乌鲁木齐市地区城市绿化建坪的主要草种；苇状羊茅、紫羊茅、羊茅可作为伴生草种；多年生黑麦草发芽快可作为草坪建植的保护草种。经草坪草质量综合评价，供试草坪草种中草地早熟禾品种Wembley，Andante，Broadway，Oxford，Conni，Mordona，苇状羊茅品种Cochise，紫羊茅品种Laxton，Penille，Gondolin，多年生黑麦草Juvcntus，Pickwick等均适宜在新疆乌鲁木齐及其类似地区种植。     

强优势恢复系温恢845的选育与应用研究

选用株型好的带有广亲和基因和野败型恢复基因的恢复系培矮64为母本,以丰产性好的印水型恢复系、兼抗褐稻虱的韩国中籼水源297为父本,通过有性杂交和定向选择育成强优势恢复系温恢845.该恢复系具有恢复谱广、恢复力强、配合力高、生育期适中、较抗稻瘟病等特点,所配组合Ⅱ优845已通过浙江省区试.并对温恢845的广谱恢复性及其应用前景进行分析和讨论.     

Location of a major susceptibility locus for familial schizophrenia on chromosome 1q21-q22

Schizophrenia is a complex disorder, and there is substantial evidence supporting a genetic etiology. Despite this, prior attempts to localize susceptibility loci have produced predominantly suggestive findings. A genome-wide scan for schizophrenia susceptibility loci in 22 extended families with high rates of schizophrenia provided highly significant evidence of linkage to chromosome 1 (1q21-q22), with a maximum heterogeneity logarithm of the likelihood of linkage (lod) score of 6.50. This linkage result should provide sufficient power to allow the positional cloning of the underlying susceptibility gene.     

Genetic mapping of a murine leukemia virus-inducing locus of AKR mice

The chromosomal location of one of the two murine leukemia virus-inducing loci of AKR mice has been determined. The locus, which appears to be the integrated genome of the virus, is designated Akv-1, and is on linkage group 1, 12 map units from Gpi-1, with gene order c-Gpi-1-Akv-1. This identification of a closely linked gene whose phenotype is independent of virus expression should facilitate analysis of the biologic importance of the Akv-1 locus.     

Phosphoglucomutase: evidence for a new locus expressed in human milk

Electrophoretic study of phosphoglucomutase (PGM) in human milk revealed different patterns that can be explained by the existence of a locus distinct from the common PGM1, PGM2, and PGM3. One hundred and forty samples were tested and the results showed four different alleles of PGM4 whose frequencies were under Hardy-Weinberg equilibrium.