Pleistocene brown bears in the mid-continent of North America

Current biogeographic models hypothesize that brown bears migrated from Asia to the New World ~100 to 50 thousand years ago but did not reach areas south of Beringia until ~13 to 12 thousand years ago, after the opening of a mid-continental ice-free corridor. We report a 26-thousand-year-old brown bear fossil from central Alberta, well south of Beringia. Mitochondrial DNA recovered from the specimen shows that it belongs to the same clade of bears inhabiting southern Canada and the northern United States today and that modern brown bears in this region are probably descended from populations that persisted south of the southern glacial margin during the Last Glacial Maximum.     

Genomic sequencing of Pleistocene cave bears

Despite the greater information content of genomic DNA, ancient DNA studies have largely been limited to the amplification of mitochondrial sequences. Here we describe metagenomic libraries constructed with unamplified DNA extracted from skeletal remains of two 40,000-year-old extinct cave bears. Analysis of approximately 1 megabase of sequence from each library showed that despite significant microbial contamination, 5.8 and 1.1% of clones contained cave bear inserts, yielding 26,861 base pairs of cave bear genome sequence. Comparison of cave bear and modern bear sequences revealed the evolutionary relationship of these lineages. The metagenomic approach used here establishes the feasibility of ancient DNA genome sequencing programs.     

Dynamics of Pleistocene population extinctions in Beringian brown bears

The climatic and environmental changes associated with the last glaciation (90,000 to 10,000 years before the present; 90 to 10 ka B.P.) are an important example of the effects of global climate change on biological diversity. These effects were particularly marked in Beringia (northeastern Siberia, northwestern North America, and the exposed Bering Strait) during the late Pleistocene. To investigate the evolutionary impact of these events, we studied genetic change in the brown bear, Ursus arctos, in eastern Beringia over the past 60,000 years using DNA preserved in permafrost remains. A marked degree of genetic structure is observed in populations throughout this period despite local extinctions, reinvasions, and potential interspecies competition with the short-faced bear, Arctodus simus. The major phylogeographic changes occurred 35 to 21 ka B.P., before the glacial maximum, and little change is observed after this time. Late Pleistocene histories of mammalian taxa may be more complex than those that might be inferred from the fossil record or contemporary DNA sequences alone.     

Climate-driven range expansion and morphological evolution in a marine gastropod

Little is known about the phenotypic consequences of global climate change, despite the excellent Pleistocene fossil record of many taxa. We used morphological measurements from extant and Pleistocene populations of a marine gastropod (Acanthinucella spirata) in conjunction with mitochondrial DNA sequence variation from living populations to determine how populations responded phenotypically to Pleistocene climatic changes. Northern populations show little sequence variation as compared to southern populations, a pattern consistent with a recent northward range expansion. These recently recolonized northern populations also contain shell morphologies that are absent in extant southern populations and throughout the Pleistocene fossil record. Thus, contrary to traditional expectations that morphological evolution should occur largely within Pleistocene refugia, our data show that geographical range shifts in response to climatic change can lead to significant morphological evolution.     

Widespread origins of domestic horse lineages

Domestication entails control of wild species and is generally regarded as a complex process confined to a restricted area and culture. Previous DNA sequence analyses of several domestic species have suggested only a limited number of origination events. We analyzed mitochondrial DNA (mtDNA) control region sequences of 191 domestic horses and found a high diversity of matrilines. Sequence analysis of equids from archaeological sites and late Pleistocene deposits showed that this diversity was not due to an accelerated mutation rate or an ancient domestication event. Consequently, high mtDNA sequence diversity of horses implies an unprecedented and widespread integration of matrilines and an extensive utilization and taming of wild horses. However, genetic variation at nuclear markers is partitioned among horse breeds and may reflect sex-biased dispersal and breeding.     

黑熊、棕熊肝功能测定分析

为了利用血清学方法检测熊的肝脏疾病，采用肝功能试验的方法，对黑熊棕熊血清总蛋白TP（Serum total protein)、血清白蛋白A（Albumin)、G血清球蛋白（Globulin)、血清丙氨酸氨基转移酶ALT（Alanine aminotrans ferase)进行了测定。结果表明：32只被检测的黑熊、棕熊中，患有肝脏疾病的5只熊，ALT平均值为105.9；健康熊25只ALT平均值21.24。患病组与对照组ALT的μ0.01=2.576，差异显著。丙氨酸氨基转移酶ALT对检测熊的肝脏疾病有决定意义。     

患骨肿瘤黑熊不同组织SOD和LDH同工酶分析

为了评价患骨肿瘤黑熊个体SOD和LDH同工酶酶谱变化特点,采用聚丙烯酰胺凝胶电泳法,对黑熊患骨肿瘤个体和正常个体心脏、肝脏、肾脏、脑、肺5种组织中SOD、LDH同工酶进行比较分析。结果表明,在5种组织内,有3种(心、肾、肺)SOD同工酶电泳谱带出现异常,其中患病个体都缺失SOD10,同工酶活力变化不大。主要检测出5种LDH同工酶,各组织内患病个体和正常个体的同工酶谱带数量和种类相同,但活性上有较大差异。可见,患骨肿瘤个体的SOD和LDH同工酶酶谱在表观正常的组织中已出现异常,并有某些肿瘤细胞的代谢特征。     

Glacial and pluvial periods: their relationship revealed by pleistocene sediments of the red sea and gulf of aden

Oxygen isotope analyses of planktonic foraminifera from the Red Sea and Gulf of Aden indicate that during periods of maximum continental and polar glaciation in the late Pleistocene, the Red Sea was subject to strong evaporation. Between glacial maximums the salinity of the Red Sea was equal to or below that of the open ocean. This suggests that high-latitude glacial periods corresponded in time to interpluvial stages in the present-day desert belt of northern Africa, whereas high-latitude interglacial periods coincided with pluvial stages.     

棕熊亚种一新纪录

本文对分布在新疆三大山系的棕熊进行了观察研究,发现分布在阿勒泰的棕熊与分布在阿尔金山的青藏亚种(Ursus arctos pruinosus Blyth)和分布在天山的天山亚种(Ursus arctos issabellinus Horsfield)有显著差异,而与文献中记述的分布在苏联西伯利亚向东至山脉的普通棕熊亚种相同,故阿勒泰棕熊是中国棕熊亚种一新纪录(Ursus a. arctos).     

Comment on "Reconstructing the origin of Andaman islanders"

On the basis of mitochondrial DNA sequence analyses, Thangaraj et al. (Brevia, 13 May 2005, p. 996) proposed that Andaman islanders descended from the first humans to migrate out of Africa. We identified mitochondrial DNA from two northeast Indian Rajbanshi individuals that shares three specific mutations with the M31a lineage observed in the Great Andamanese, which suggests that the predecessor of haplogroup M31 originated on the Indian subcontinent.     

东北黑熊不同基因组DNA模板来源的比较研究

文章主要探讨使用黑熊毛发作为试验材料替代其他生物样品进行遗传多样性研究的可行性,筛选满足试验需求的最佳使用量.以延边白头山制药有限公司养熊场的4头成年东北黑熊为试验材料,分别5次拾取2头黑熊铁笼内散落的带有毛囊的50、100根毛发,对麻醉的2头黑熊抽取全血3 mL以及皮下结缔组织1 g,并分别采用不同方法提取基因组DNA.以微卫星位点ABB12和UT35为引物,设置20、50、100 ng·μL-13种模板浓度进行PCR扩增.结果显示,采用50 ng·μL-1的模板浓度均可获得较好的PCR产物,采用聚丙烯酰胺凝胶电泳对扩增基因具有较好的分辨效果.毛发DNA、血液DNA和组织DNA的PCR产物数量和质量并无明显差异.毛发数量与所提取的DNA浓度有一定关系.利用15个毛发DNA的PCR产物进行聚丙烯酰胺凝胶电泳,均可观察到清晰的条带.研究结果进一步证明毛发DNA可作为东北黑熊遗传多样性研究的试验材料.     

活熊取胆胆汁与商品熊胆胆汁酸成分的比较研究

本文报道了活熊取胆胆汁的生药学特征,并采用GC—MS—计算机联用仪测定了活熊取胆胆汁与商品熊胆水解物中胆汁酸的种类及含量,通过比较确认了活熊取胆胆汁代替商品熊胆的可行性。     

Oxygen isotope composition of subglacially precipitated calcite: possible paleoclimatic implications

Isotopic analyses of subglacially precipitated calcite from near a modern temperate glacier show that the delta(18)O (= (18)O/(16)O relative to standard mean ocean water) of the calcite records the delta(18)O of the ice from that glacier. It may therefore be possible to determine the delta(18)O of Pleistocene ice sheets on the basis of isotopic analyses of calcite formed under that ancient ice. This, in turn, would allow estimation of the delta(18)O of Pleistocene oceans and correction of the paleotemperature scale based on foraminiferal oxygen isotopic analyses.     

野生亚东鲑群体遗传多样性及其种质来源研究

以褐鳟(Salmo trutta)日本品系和亚东鲑群体为研究对象,通过测定上述两个群体8个微卫星标记和线粒体D-loop基因多态性,综合分析日本品系和亚东鲑群体遗传多样性及其种质来源。结果表明,褐鳟日本品系等位基因数为2~10个,亚东鲑群体为4~9个,平均有效等位基因数分别为3.1304和3.8988;观测杂合度范围分别为0.3404~0.7128和0.1020~0.8776,其中褐鳟日本品系平均观测杂合度为0.5612,亚东鲑群体为0.5510,期望杂合度分别为0.4671~0.7794和0.5216~0.7932;褐鳟日本品系多态信息含量(PIC)为0.3680~0.7440,平均为0.5964,而亚东群体PIC为0.4660~0.8370,平均为0.5926。研究分析褐鳟、亚东鲑线粒体D-loop基因序列和欧洲褐鳟已知五个地理居群D-loop基因序列,日本品系褐鳟和亚东鲑与欧洲大西洋居群褐鳟聚在一支,亲缘关系最近。     

中国飞蝗线粒体COI基因片段的扩增

对中国飞蝗各亚种线粒体DNA的COI基因片段进行了扩增并测序。结果表明,扩增产物为单一带,大小约为1.3kb。对此扩增产物序列分析证明所扩增的COI基因序列是一个含混不清的序列,说明在中国飞蝗不同亚种的基因组DNA中存在线粒体的假基因序列,因此以飞蝗基因组DNA为模板PCR扩出的mtDNA COI基因片段不适宜用作分析飞蝗种群遗传和系统发育的分子标记。     

Early origin and recent expansion of Plasmodium falciparum

The emergence of virulent Plasmodium falciparum in Africa within the past 6000 years as a result of a cascade of changes in human behavior and mosquito transmission has recently been hypothesized. Here, we provide genetic evidence for a sudden increase in the African malaria parasite population about 10,000 years ago, followed by migration to other regions on the basis of variation in 100 worldwide mitochondrial DNA sequences. However, both the world and some regional populations appear to be older (50,000 to 100,000 years old), suggesting an earlier wave of migration out of Africa, perhaps during the Pleistocene migration of human beings.     

胆汁引流对黑熊健康状况影响的研究

通过三个实验来研究取胆汁对熊的健康状况的影响。首先,比较了取胆汁熊和没有取胆汁熊的健康状态;其次,比较了引流3年以上的熊和没有进行引流熊的健康状况;最后,比较了不同取胆汁方式熊的健康状况。实验证明,引流取胆汁影响了熊的身体健康,其中,引流取胆汁对熊的危害明显,穿刺取胆汁对熊的危害较小。引流取胆汁对熊的健康影响主要体现在易患胆囊炎症、胆结石,还容易发生脂溶性维生素缺乏症状。     

Host-to-parasite gene transfer in flowering plants: phylogenetic evidence from Malpighiales

Horizontal gene transfer (HGT) between sexually unrelated species has recently been documented for higher plants, but mechanistic explanations for HGTs have remained speculative. We show that a parasitic relationship may facilitate HGT between flowering plants. The endophytic parasites Rafflesiaceae are placed in the diverse order Malpighiales. Our multigene phylogenetic analyses of Malpighiales show that mitochondrial (matR) and nuclear loci (18S ribosomal DNA and PHYC) place Rafflesiaceae in Malpighiales, perhaps near Ochnaceae/Clusiaceae. Mitochondrial nad1B-C, however, groups them within Vitaceae, near their obligate host Tetrastigma. These discordant phylogenetic hypotheses strongly suggest that part of the mitochondrial genome in Rafflesiaceae was acquired via HGT from their hosts.     

Rise and fall of the Beringian steppe bison

The widespread extinctions of large mammals at the end of the Pleistocene epoch have often been attributed to the depredations of humans; here we present genetic evidence that questions this assumption. We used ancient DNA and Bayesian techniques to reconstruct a detailed genetic history of bison throughout the late Pleistocene and Holocene epochs. Our analyses depict a large diverse population living throughout Beringia until around 37,000 years before the present, when the population's genetic diversity began to decline dramatically. The timing of this decline correlates with environmental changes associated with the onset of the last glacial cycle, whereas archaeological evidence does not support the presence of large populations of humans in Eastern Beringia until more than 15,000 years later.     

Mitochondrial biogenesis in mammals: the role of endogenous nitric oxide

Nitric oxide was found to trigger mitochondrial biogenesis in cells as diverse as brown adipocytes and 3T3-L1, U937, and HeLa cells. This effect of nitric oxide was dependent on guanosine 3',5'-monophosphate (cGMP) and was mediated by the induction of peroxisome proliferator-activated receptor gamma coactivator 1alpha, a master regulator of mitochondrial biogenesis. Moreover, the mitochondrial biogenesis induced by exposure to cold was markedly reduced in brown adipose tissue of endothelial nitric oxide synthase null-mutant (eNOS-/-) mice, which had a reduced metabolic rate and accelerated weight gain as compared to wild-type mice. Thus, a nitric oxide-cGMP-dependent pathway controls mitochondrial biogenesis and body energy balance.