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.     

熊人工授精的研究进展

论述了有关熊人工授精的研究进展．主要内容包括熊的性行为、采精、精液品质、精液的冷冻保存以及输精．     

眠乃宁对黑熊的麻醉试验

为了掌握眼乃宁的药性和适用于黑熊的麻醉剂量，先后对218头黑熊做有效麻醉剂量的选择与观察，结果表明，眼乃宁对黑熊的最佳麻醉剂量为3．5mL／100kg体重．     

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.     

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.     

活体引流术熊胆汁的细菌分离与鉴定

为了解活体引流术后熊胆汁中的细菌分布情况及其耐药性，从延边某熊场无菌采集6只熊的胆汁样本，进行细菌分离鉴定及药敏试验．结果共分离出细菌12株，其中大肠杆菌6株，金黄色葡萄球菌3株，绿脓杆菌2株，沙门氏菌1株．药敏试验结果表明，大肠杆菌对头孢噻肟、氯霉素和头孢唑啉高度敏感；绿脓杆菌对庆大霉素高度敏感；沙门氏菌对氧氟沙星及诺氟沙星高度敏感；金黄色葡萄球菌对氨苄西林／舒巴坦、头孢唑啉、哌拉西林、头孢哌酮、氨苄西林、红霉素和头孢氨苄等高度敏感．     

Ratio of serum urea to serum creatinine in wild black bears

In winter, the ratio of serum urea to serum creatinine is 10 or less in denning female and male bears. In midsummer it is 22 or more, similar to that of other mammals. However, in late summer and early fall, while food is available, the urea-to-creatinine ratio approaches or becomes 10 or less. The low value of this ratio appears to indicate the biochemical state of hibernation, and many bears are in this state weeks before they den.     

Hibernation in black bears: independence of metabolic suppression from body temperature

Black bears hibernate for 5 to 7 months a year and, during this time, do not eat, drink, urinate, or defecate. We measured metabolic rate and body temperature in hibernating black bears and found that they suppress metabolism to 25% of basal rates while regulating body temperature from 30° to 36°C, in multiday cycles. Heart rates were reduced from 55 to as few as 9 beats per minute, with profound sinus arrhythmia. After returning to normal body temperature and emerging from dens, bears maintained a reduced metabolic rate for up to 3 weeks. The pronounced reduction and delayed recovery of metabolic rate in hibernating bears suggest that the majority of metabolic suppression during hibernation is independent of lowered body temperature.     

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history.     

Human lymphocyte antigen reactivity modified by neuraminidase

Human lymphocytes treated with neuraminidase (from Vibrio cholera) are more susceptible to lysis with antiserums directed against HL-A antigens in the cytotoxicity test than are the corresponding cells incubated in buffer. Enzymetreated cells are also lysed by antibodies other than those directed against HL-A, but control cells are not. The extra sensitivity to antibody disappears after 2 to 6 days in tissue culture.     

浅析心理契约视角下的图书馆人本管理

心理契约本质上是一种情感契约,是形成图书馆组织凝聚力和团队意识的一种无形的手段,是提升图书馆人力资源效能的新模式。     

Human hypertension caused by mutations in WNK kinases

Hypertension is a major public health problem of largely unknown cause. Here, we identify two genes causing pseudohypoaldosteronism type II, a Mendelian trait featuring hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Both genes encode members of the WNK family of serine-threonine kinases. Disease-causing mutations in WNK1 are large intronic deletions that increase WNK1 expression. The mutations in WNK4 are missense, which cluster in a short, highly conserved segment of the encoded protein. Both proteins localize to the distal nephron, a kidney segment involved in salt, K+, and pH homeostasis. WNK1 is cytoplasmic, whereas WNK4 localizes to tight junctions. The WNK kinases and their associated signaling pathway(s) may offer new targets for the development of antihypertensive drugs.     

Shock and tissue injury induced by recombinant human cachectin

Cachectin (tumor necrosis factor), a protein produced in large quantities by endotoxin-activated macrophages, has been implicated as an important mediator of the lethal effect of endotoxin. Recombinant human cachectin was infused into rats in an effort to determine whether cachectin, by itself, can elicit the derangements of host physiology caused by administration of endotoxin. When administered in quantities similar to those produced endogenously in response to endotoxin, cachectin causes hypotension, metabolic acidosis, hemoconcentration, and death within minutes to hours, as a result of respiratory arrest. Hyperglycemia and hyperkalemia were also observed after infusion. At necropsy, diffuse pulmonary inflammation and hemorrhage were apparent on gross and histopathologic examination, along with ischemic and hemorrhagic lesions of the gastrointestinal tract, and acute renal tubular necrosis. Thus, it appears that a single protein mediator (cachectin) is capable of inducing many of the deleterious effects of endotoxin.     

Regulation of Migration,Phagocytosis and Apoptosis of Human Neutrophils by Recombinant Human Intestinal Alkaline Phosphatase

The purpose of this study was to explore the effects of recombinant human intestinal alkaline phosphatase(recIAP) on human neutrophils in vitro, and the migration, phagocytosis, apoptosis in presence and absence of LPS. In this study, freshly extracted human neutrophils were used to establish an inflammatory cell model, and the control group, recIAP group, LPS group and recIAP +LPS group were set up to stimulate the model. The migration of neutrophils was detected by agarose gel drop method. Flu...