Adaptive intraspecific divergence: An example using the animal cytochrome <Emphasis Type="Italic">b</Emphasis> gene

The topologies of phylogenetic trees characterized by a high level of intraspecific divergence between the phylogenetic DNA groups (clades) are often explained in terms of the theory of Pleistocene refugia. To elucidate the issue of the adaptive role of intraspecific divergence, the changes in the physicochemical properties of amino acids in the course of cladogenesis (MM01 model of the TreeSAAP 3.2 package) were analyzed in this work using as an example the nucleotide sequences of the cytochrome b gene in some species of northern animals (lemmings, redbacked voles, chipmunks, flying squirrels, ermines). It was shown that the process of intraspecific divergence was rarely accompanied by radical amino acid substitutions in cytochrome b caused by adaptation (directional selection). In connection with this, the hypothesis is discussed according to which the adaptive variants formed in the species at the peak of cold were lost with climatic warming due to the drift or selection against individuals adapted to cold.     

Mitochondrial haplogroup N1a phylogeography,with implication to the origin of European farmers

Background  

Tracing the genetic origin of central European farmer N1a lineages can provide a unique opportunity to assess the patterns of the farming technology spread into central Europe in the human prehistory. Here, we have chosen twelve N1a samples from modern populations which are most similar with the farmer N1a types and performed the complete mitochondrial DNA genome sequencing analysis. To assess the genetic and phylogeographic relationship, we performed a detailed survey of modern published N1a types from Eurasian and African populations.     

基于ISSR标记的辽宁4个东北林蛙种群遗传多样性分析

辽宁是东北林蛙Rana dybowskii主要分布地之一,种群数量巨大,其群体遗传多样性有待评估.本研究应用ISSR标记技术对东北林蛙4个种群105个样本进行研究,5个引物共获得44条清晰谱带,4个种群的多态位点率均大于75%,Nei's基因多样性为0.2851,Shannon信息指数为0.4476,显示了较高的遗传多样性.对遗传分化系数、Nei's遗传距离、AMOVA分子变异巢式方差分析和F-统计量等遗传参数的统计结果表明,辽宁东北林蛙种群间已经出现一定程度的遗传分化,分析认为,自然屏障(高山和平原等)以及栖息地片段化是其遗传分化形成的主要因素.     

莲藕干物质和氮磷钾养分的累积与分配研究

连续2年采用盆栽试验研究了莲藕（Nelumbo nucifera Gaertn）干物质和氮磷钾养分的累积与分配规律。结果表明：莲藕苗期以叶片生长并积累光合产物为主,膨大根状茎成型后,叶片、叶柄和根状茎中的干物质不断运输并贮存到膨大根状茎中,以产量形成为主,干物质累积总量增长呈＂慢-快-稳定＂的变化趋势;氮磷钾累积量与干物质累积量变化趋势一致,并与之呈极显著正相关,莲藕氮磷钾养分累积总量之比为1∶0.12∶1.31。移栽后97-160 d是莲藕产量形成的关键时期,不仅叶片、叶柄和根状茎中的氮磷钾随同干物质运输并贮存到膨大根状茎中,根系还从土壤中吸收更多的氮磷钾直接运输并贮存到膨大根状茎中,后者分别占同期氮磷钾累积量的69.8%、79.2%和75.0%。160 d膨大根状茎中干物质、氮、磷和钾累积量分别平均占植株总累积量的81.1%、85.2%、88.8%和80.2%。     

中国西北沙漠夜间活动的东鳖甲属昆虫二新种(鞘翅目:拟步甲科:漠甲亚科)

记述中国西北地区东鳖甲属2新种:巴丹东鳖甲A.badainica Ba,Ren&Liu sp.nov.和古尔班东鳖甲A.gurbantunggutica Ba&Ren sp.nov.,提供了主要鉴别特征和形态图,并简要讨论了其昼夜活动规律.     

血液磁极化疗法对糖尿病兔胰岛功能的影响

目的观察血液磁极化疗法(简称血磁治疗)对糖尿病(DM)的治疗效果和对胰岛功能的影响。方法制备了四氧嘧啶DM兔模型20只,随机分为两组,即DM模型血磁治疗组及DM模型未治疗组,同时设立正常对照组10只,分别测定治疗前后空腹血糖(FPG)、糖化血红蛋白(HbA1c)、胰岛素(INS)及C-肽(C-P),并于观察期结束后处死动物取胰腺组织常规石蜡包埋切片,行HE及Mallory三色法特殊染色观察3组胰岛形态学变化。结果血磁治疗显著降低DM兔的FPG(P<0.001)。DM治疗组INS及C-P水平较治疗前明显升高(P<0.01),与未治疗组相比差异显著(P<0.05)。胰岛病理改变可见治疗组β细胞数量明显多于DM未治疗组,提示血磁疗法具有促进胰岛修复,改善胰岛功能的作用。结论血磁疗法能够促进DM时受损胰岛组织的修复,改善胰岛β细胞分泌功能,降血糖作用明显。     

Surface N balances and reactive N loss to the environment from global intensive agricultural production systems for the period 1970-2030

Data for the historical years 1970 and 1995 and the FAO-Agriculture Towards 2030 projection are used to calculate N inputs (N fertilizer, animal manure, biological N fixation and atmospheric deposition) and the N export from the field in harvested crops and grass and grass consumption by grazing animals. In most industrialized countries we see a gradual increase of the overall N recovery of the intensive agricultural production systems over the whole 1970-2030 period. In contrast, low N input systems in many developing countries sustained low crop yields for many years but at the cost of soil fertility by depleting soil nutrient pools. In most developing countries the N recovery will increase in the coming decades by increasing efficiencies of N use in both crop and livestock production systems. The surface balance surplus of N is lost from the agricultural system via different pathways, including NH3 volatilization, denitrification, N2O and NO emissions, and nitrate leaching from the root zone. Global NH3-N emissions from fertilizer and animal manure application and stored manure increased from 18 to 34 Tg·yr-1 between 1970 and 1995, and will further increase to 44 Tg·yr-1 in 2030. Similar developments are seen for N2O-N (2.0 Tg·yr-1 in 1970, 2.7 Tg·yr-1 in 1995 and 3.5 Tg·yr-1 in 2030) and NO-N emissions (1.1 Tg·yr-1 in 1970, 1.5Tg·yr-1 in 1995 and 2.0 Tg·yr-1 in 2030).     

Distribution of nucleotide substitutions in human mitochondrial DNA genes

To analyze the distribution pattern of nucleotide substitutions in human mitochondrial DNA (mtDNA), mutational spectra of the mitochondrial genes were reconstructed. The reconstruction procedure is based on the mutation distribution data for 47 monophyletic mtDNA clusters, to which 794 examined mtDNA sequences encoding for tRNAs, rRNAs, and mitochondrial proteins are attributed. One of specific features of mitochondrial mutational spectra revealed was homoplasy of the mutations (the mean mutation number per variable nucleotide site in the coding region varied from 1.09 to 1.43). It was established that in the mtDNA genes maximum mutational constraint fell onto the guanine bases, albeit the content of these bases in the mtDNA L-chains was minimal. Maximal bias towards parallel G to A transitions was observed for rRNA genes, with the protein-and tRNA-encoding genes ranking next. Despite the fact that the differences in the average G-nucleotides content and variability between the genes of two mtDNA segments located between the OriH and OriL were statistically significant, the results did not provide the conclusion that the G-nucleotide instability observed in the mtDNA L-spectra was determined by the mechanism of asynchronous mtDNA replication, along with the deamination of cytosines in the H-chain regions, which remained single-stranded during replication.Translated from Genetika, Vol. 41, No. 1, 2005, pp. 93–99.Original Russian Text Copyright © 2005 by Malyarchuk.     

Origin of Caucasoid-Specific Mitochondrial DNA Lineages in the Ethnic Groups of the Altai–Sayan Region

The data on sequence variation in the first hypervariable segment (HVSI) of human mitochondrial DNA (mtDNA) representing Caucasoid mtDNA lineages in the gene pools of Altaians and Khakassians are presented. Identification of the subgroups of Caucasoid mtDNA lineages found in the gene pools of the ethnic groups of the Altai–Sayan region and the adjacent territories, Altaians, Khakassians, Tuvinians, Buryats, and Yakuts was carried out. All Caucasoid mtDNA lineages belonged to groups H, HV1, J*, J1, J1b1, T1, T4, U1a, U2, U3, U4, U5a1, I, X and N1a. Taking into consideration possible contribution of southern Caucasoid and eastern European components to the formation of the anthropological type of Altai–Sayan ethnic groups, distribution of the revealed Caucasoid mtDNA lineages among the ethnic groups of the Central Asia, Western Asia, Caucasus, and Eastern Europe was examined. The applied approach permitted identification of 60% of mtDNA types the majority of which had southern Caucasoid origin. Less than 10% of mtDNA types were of eastern European origin. The gene pools of Altaians and Khakassians displayed the presence of autochthonous components represented by mtDNA types from subgroups U2 and U4.     

羊草与其主要伴生种竞争与共存的格局分析

在羊草种群与其它植物种群的交错区,应用频度、格避形式,格局强度指数对羊草及其主要伴生种之间的共存格局进行了分析。结果表明,羊草及其主要伴生种的格局呈多样化,集聚格局形式是羊草抵御外来物种入侵,或者是自身扩散的一种对策,羊草与其主要伴生种之间存在竞争与共存作用,羊草与芦苇之间通过拮抗作用实现竞争与共存,羊草与鸡儿肠通过竞争而实现共存,光稃茅香,碱茅以营养繁殖策略实现与羊草竞争,指子茅的生长受羊草竞争的抑制。