Comment on "Ongoing adaptive evolution of ASPM, a brain size determinant in Homo sapiens" and "Microcephalin, a gene regulating brain size, continues to evolve adaptively in humans"

Mekel-Bobrov et al. and Evans et al. (Reports, 9 Sept. 2005, p. 1720 and p. 1717, respectively) examined sequence data from modern humans within two gene regions associated with brain development, ASPM and microcephalin, and concluded that selection of these genes must be ongoing. We show that models of human history that include both population growth and spatial structure can generate the observed patterns without selection.     

Ongoing adaptive evolution of ASPM, a brain size determinant in Homo sapiens

The gene ASPM (abnormal spindle-like microcephaly associated) is a specific regulator of brain size, and its evolution in the lineage leading to Homo sapiens was driven by strong positive selection. Here, we show that one genetic variant of ASPM in humans arose merely about 5800 years ago and has since swept to high frequency under strong positive selection. These findings, especially the remarkably young age of the positively selected variant, suggest that the human brain is still undergoing rapid adaptive evolution.     

Relative brain size: a new measure

The relation of the volume of the endocranial cavity to the area of the foramen magnum is a measure of relative brain size in mammals. The outstanding advantage of this method is that only a skull is required for a set of measurements.     

OsMas1, a novel maspardin protein gene,confers tolerance to salt and drought stresses by regulating ABA signaling in rice

Drought and salt stresses, the major environmental abiotic stresses in agriculture worldwide, affect plant growth, crop productivity, and quality. Therefore, developing crops with higher drought and salt tolerance is highly desirable. This study reported the isolation, biological function, and molecular characterization of a novel maspardin gene, OsMas1, from rice. The OsMas1 protein was localized to the cytoplasm. The expression levels of OsMas1 were up-regulated under mannitol, PEG6000, NaCl, ...     

Comment on "Ongoing adaptive evolution of ASPM, a brain size determinant in Homo sapiens"

Mekel-Bobrov et al. (Reports, 9 September 2005, p. 1720) suggested that ASPM, a gene associated with microcephaly, underwent natural selection within the last 500 to 14,100 years. Their analyses based on comparison with computer simulations indicated that ASPM had an unusual pattern of variation. However, when we compare ASPM empirically to a large number of other loci, its variation is not unusual and does not support selection.     

Characterization and map-based cloning of miniature2-m1, a gene controlling kernel size in maize

Kernel development plays an important role in determining kernel size in maize. Here we present the cloning and characterization of a maize gene, nitrate transporter1.5(NRT1.5), which controls small kernel phenotype by playing an important role in kernel development. A novel recessive small kernel mutant miniature2-m1(mn2-m1) was isolated from self-pollinated progenies of breeding materials. The mutant spontaneously showed small kernel character arresting both embryo and endosperm development at an early stage after pollination. Utilizing 21 polymorphic SSR markers, the mn2-m1 locus was limited to a 209.9-kb interval using 9 176 recessive individuals of a BC1 segregating population from mn2-m1/B73. Only one annotated gene was located in this 209.9 kb region, Zm00001 d019294, which was predicted to encode nitrate transporter1.5(NRT1.5). Allelism tests confirmed that mn2-m1 was allelic to miniature2-m2(mn2-m2) and miniature2-710 B(mn2-710 B). The mn2-m1 and mn2-m2 alleles both had nucleotide deletions in the coding region resulting in premature termination, and the mn2-710 B allele had some missence mutations. Subcellular localization showed that Miniature 2(MN2) is localized in the plasma membrane. Quantitative real-time PCR(qRT-PCR) analysis revealed that the expression of MN2 and some genes involved in the basal endosperm transfer layer(BETL) and embryo surrounding region(ESR) development were affected in mn2-m1 seeds. These results suggested that MN2 plays an important role in maize seed development.     

营养因子对动物基因表达的调控作用

近些年来,越来越多的学者开始研究营养因子对基因表达的调控作用。基于这方面的研究资料,综述葡萄糖、脂肪和多不饱和脂肪酸、蛋白质及氨基酸、维生素A、D、E、B2、B6、C、生物素、叶酸、锌和铁等营养因子对基因表达的调控作用,以期初步揭示营养在动物生存和生产中的本质作用。     

AtPIP5K2基因参与拟南芥盐胁迫的调节过程

植物在长期进化过程中演化出不同机制来适应环境中的各种胁迫,如盐碱、干旱等.该研究从拟南芥T-DNA插入突变体库中筛选到一个对盐反应不敏感的突变株系eto(enhanced tolerance to osmotic stress),种子萌发和幼苗生长试验表明eto突变株系早期生长发育对盐胁迫不敏感.TAIL-PCR分析表明eto突变株系中T DNA插入在拟南芥1号染色体上(BAC F3M18的27502位置),位于拟南芥At1g77740基因起始密码子前487 bp处,该基因编码磷脂酰肌醇-4-磷酸 -5-激酶(AtPIP5K2),共分离分析表明T-DNA插入与盐不敏感性紧密连锁.以野生型拟南芥总RNA为模板,克隆拟南芥AtPIP5K2基因cDNA,其开放读码框为2 265bp,编码755个氨基酸.与已报道物种PIPKs基因氨基酸序列比较分析表明,AtPIP5K2与植物PIPKs基因氨基酸相似性高达62%～75%,但与其他生物物种PIPKs基因之间的氨基酸相似性仅为33%～37%;AtPIP5K2推导的氨基酸序列中含有植物PIPKs基因所具有的高度保守区域“PIPKc"、“MORN repeat".进一步分析表明AtPIP5K2基因在拟南芥根及莲座叶片中表达量较强,并且由于T-DNA的插入,使eto突变株系与野生型相比,其AtPIP5K2基因过量表达,表明AtPIP5K2基因编码的产物可能参与调节拟南芥适应盐胁迫的调节反应.      

The potential for respiratory droplet-transmissible A/H5N1 influenza virus to evolve in a mammalian host

Avian A/H5N1 influenza viruses pose a pandemic threat. As few as five amino acid substitutions, or four with reassortment, might be sufficient for mammal-to-mammal transmission through respiratory droplets. From surveillance data, we found that two of these substitutions are common in A/H5N1 viruses, and thus, some viruses might require only three additional substitutions to become transmissible via respiratory droplets between mammals. We used a mathematical model of within-host virus evolution to study factors that could increase and decrease the probability of the remaining substitutions evolving after the virus has infected a mammalian host. These factors, combined with the presence of some of these substitutions in circulating strains, make a virus evolving in nature a potentially serious threat. These results highlight critical areas in which more data are needed for assessing, and potentially averting, this threat.     

Chronic Parkinsonism in humans due to a product of meperidine-analog synthesis

Four persons developed marked parkinsonism after using an illicit drug intravenously. Analysis of the substance injected by two of these patients revealed primarily 1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine (MPTP) with trace amounts of 1-methyl-4-phenyl-4-propionoxy-piperidine (MPPP). On the basis of the striking parkinsonian features observed in our patients, and additional pathological data from one previously reported case, it is proposed that this chemical selectively damages cells in the substantia nigra.     

Predisposition to hookworm infection in humans

Frequency distributions of parasitic helminths within human communities are invariably highly aggregated, the majority of worms occurring in relatively small fractions of the host populations. It has been suggested that the heavily infected individuals are predisposed to this state, not by chance, but by as yet undefined genetic, ecological, behavioral, or social factors. Analyses of individual post-treatment patterns of hookworm reinfection among 112 villagers in an endemic area of West Bengal provide quantitative evidence of predisposition to heavy infection. This observation has implications for the design of control programs based on chemotherapy because of the potential economic advantage of selective or targeted treatment as opposed to mass or blanket treatment.     

Conservation of brain amyloid proteins in aged mammals and humans with Alzheimer's disease

The formation of clusters of altered axons and dendrites surrounding extracellular deposits of amyloid filaments (neuritic plaques) is a major feature of the human brain in both aging and Alzheimer's disease. A panel of antibodies against amyloid filaments and their constituent proteins from humans with Alzheimer's disease cross-reacted with neuritic plaque and cerebrovascular amyloid deposits in five other species of aged mammals, including monkey, orangutan, polar bear, and dog. Antibodies to a 28-amino acid peptide representing the partial protein sequence of the human amyloid filaments recognized the cortical and microvascular amyloid of all of the aged mammals examined. Plaque amyloid, plaque neurites, and neuronal cell bodies in the aged animals showed no reaction with antibodies to human paired helical filaments. Thus, with age, the amyloid proteins associated with progressive cortical degeneration in Alzheimer's disease are also deposited in the brains of other mammals. Aged primates can provide biochemically relevant models for principal features of Alzheimer's disease: cerebrovascular amyloidosis and neuritic plaque formation.     

玉米ZmEREB46基因调控耐渍性功能探究

为鉴定和发掘玉米渍水胁迫抗性基因,克隆玉米ERF家族成员ZmEREB46（Zm00001d015759）基因,同时对该基因进行重测序分析、功能变异位点鉴定以及表达模式分析,并进一步在模式植物拟南芥中初步探究ZmEREB46参与耐渍的功能。结果显示,ZmEREB46编码1个AP2/EREBP类转录因子;相较于耐渍自交系A3237,ZmEREB46基因编码区及启动子区在渍水敏感自交系A3239中分别存在1个G/A的转换以及1个911 bp片段插入,911 bp片段的插入显著抑制了渍水敏感自交系A3239中ZmEREB46基因的表达;亚细胞定位结果显示,ZmEREB46定位在细胞核中;荧光定量PCR结果显示,ZmEREB46受渍水胁迫诱导上调表达,渍水处理8 h后ZmEREB46在耐渍自交系A3237中的表达量是渍水敏感自交系A3239中的2倍。结果表明,ZmEREB46在拟南芥中过量表达提高了拟南芥苗期的耐渍性。     

猪重要性状全基因组关联分析的研究进展

目的揭示大白猪丝氨酸/苏氨酸激酶32B (serine/threonine kinase 32B,STK32B) 基因外显子8多态性及其与母猪繁殖性状的关联。方法采用PCR产物直接测序法检测476头大白猪STK32B基因外显子8区域的SNP位点,结合2177窝母猪繁殖性能记录,采用最小二乘模型分析各SNP位点不同基因型及其单倍型组合对5个繁殖性状的影响。结果大白猪STK32B基因外显子8区域共检出3个SNP位点,包括2个同义突变位点 (A669G、C732T) 和1个错义突变位点 (C749T),分别以AA、CC、CC基因型和A、C、C等位基因的频率最高,3个位点的多态信息含量 (0.1450~0.1744) 和杂合度 (0.1574~0.1930) 总体不高。A669G位点的AA基因型可显著提高仔猪初生窝质量 (P<0.05);C732T位点与总产仔数、产活仔数、仔猪初生窝质量显著关联,其中TT基因型可显著提高总产仔数 (P<0.05),CT基因型可显著提高产活仔数和仔猪初生窝质量 (P<0.05);C749T位点的TT基因型可显著提高仔猪初生窝质量(P<0.05);3个位点单倍型组合ACC/ATC具有极显著提高总产仔数和产活仔数的效应 (P<0.01),ACC/ACT组合具有显著或极显著提高仔猪初生窝质量和断奶窝质量的效应 (P<0.05或P<0.01),ACC/GCT组合具有显著提高断奶仔猪数的效应(P<0.05)。结论研究结果初步揭示大白猪STK32B基因外显子8多态性与母猪繁殖性状显著关联,但3个位点单倍型组合的效应具有一定的性状特异性。     

圈养尖吻蝮雌体大小、窝卵数和卵大小之间的关系

尖吻蝮(Deinagkistrodon acutus)野生资源日益枯竭,食用和药用压力巨大,亟需开展人工养殖.目前尖吻蝮的人工养殖技术还不够成熟,大多数养殖场采用半地下室饲养尖吻蝮,有关该条件下尖吻蝮的繁殖特性报道较少.为促进尖吻蝮的人工养殖,2010年4-9月,在湖南永州市对半地下室圈养的尖吻蝮成体的体型指标、窝卵数、窝卵重、卵重等繁殖特征之间的关系进行了研究.结果表明:圈养尖吻蝮成年雌体产单窝柔性卵,平均窝卵数为23.0±7.8(13-37)枚(n=23);将产后雌体体重和窝卵重相加记为产前雌体体重,采用SPSS 13.0软件处理数据,设置α=0.05和α=0.01,发现产前雌体体重分别与窝卵数、窝卵重、卵重均呈显著相关性;产前雌体体长分别与窝卵数、窝卵重、卵重无显著相关性;窝卵数与卵重无显著相关性,卵重分别与卵短径、卵长径均呈显著相关性.产前体重在1000-1200g之间的雌蛇所产窝卵数和单枚卵重的数值均较大且最集中,这保证了雌体繁殖输出后代的生存优势,对尖吻蝮人工养殖挑选雌性种蛇有一定的指导意义.