洪泽湖冬春季鱼塘生境中鹬类群落特征与栖息模式

2005年冬季和2006年春季及冬季对洪泽湖东部湿地自然保护区内淮河入洪泽湖河口处(33°06′~33°07′N,118°29′~118°30′E)人工鱼塘生境中鹬类群落进行了研究。设置了4个样地,总面积157hm2。共记录到鹬类19种,其中冬季10种,春季15种。从数量上看,冬季鱼塘中的鸟类总数量远大于春季。在冬春季滞留期间,鹬类种群数量变动比较剧烈,反映了其迁徙集中的特点。鹬类主要在鱼塘生境中休息和觅食,对鱼塘内泥滩和浅水区小生境利用率最高。洪泽湖地区的鱼塘生境和渔业方式使鱼塘成为鹬类冬、春季的重要栖息地。     

洪泽湖冬春季鱼塘生境中鸻鹬类群落特征与栖息模式

2005年冬季和2006年春季及冬季对洪泽湖东部湿地自然保护区内淮河入洪泽湖河口处(33°06'～33°07'N,118°29'～118°30'E)人工鱼塘生境中鸻鹬类群落进行了研究.设置了4个样地,总面积157 hm2.共记录到鸻鹬类19种,其中冬季10种,春季15种.从数量上看,冬季鱼塘中的鸟类总数量远大于春季.在冬春季滞留期间,鸻鹬类种群数量变动比较剧烈,反映了其迁徙集中的特点.鸻鹬类主要在鱼塘生境中休息和觅食,对鱼塘内泥滩和浅水区小生境利用率最高.洪泽湖地区的鱼塘生境和渔业方式使鱼塘成为鸻鹬类冬、春季的重要栖息地.     

鄱阳湖越冬雁鸭类的种群动态与时空分布

2014年10月—2015年4月,采用样点法对鄱阳湖5个区域的47个样点中越冬雁鸭类数量与分布进行了调查。共记录雁鸭类18种,包括国家Ⅱ级重点保护动物小天鹅Cygnus columbianus和白额雁Anser albifrons。豆雁Anser fabalis的累计数量最多,其次为小天鹅、白额雁、鸿雁Anser cygnoides和罗纹鸭Anas falcata;斑嘴鸭Anas poecilorhyncha出现频次最高,其次为豆雁、小天鹅、鸿雁和白额雁;斑嘴鸭、豆雁和小天鹅出现湖泊数最多。浅水湖泊、草洲和泥滩是多数越冬雁鸭类偏好的生境。鄱阳湖国家级自然保护区集中了最多、最全的雁鸭类。     

中国鸟类新纪录——加拿大雁

<正>2014年12月21日,在天津市宁河区永定新河水域(39°15′24″N,117°26′2″E,海拔7 m)观察到4只加拿大雁(Branta canadensis)在此栖息觅食,同域亦有少量骨顶鸡(Fulica atra)、绿翅鸭(Anas crecca)、罗纹鸭(A.falcata)及赤膀鸭(A.strepera)在此活动。次日有观鸟者前往观察,未能再发现该群加拿大雁。本次观察到的加     

黑雁途经河北的新记录

2006年1月7日9：30时,在河北邢台八一水库发现了1只黑雁（Branta bernicla）。水库南岸中间部位尚有约0．3hm^2的水域没有结冰,冰水交接处的冰面上共有67只水鸟,其中绿头鸭（A．platyrhynchos）59只,斑嘴鸭（Ardedpoecilorhyncha）3只,绿翅鸭（A．crecca）3只,苍鹭（A．cinerea）1只,黑雁1只。     

围填海对盐城珍禽自然保护区越冬水鸟群落及空间分布的影响

盐城自然保护区是全球水鸟重要的越冬地之一, 随着近几十年来围填海活动强度的不断增加, 其景观格局发生了重大变化, 这种改变势必会影响越冬水鸟的群落结构和空间分布。因此, 以盐城自然保护区北缓冲区和核心区作为研究区, 根据 1975—2013 年研究区土地利用类型变化图将其划分为围垦区和未围垦区, 分析了 2009—2013 年围垦区和未围垦区之间越冬水鸟种类、数量、多样性和空间分布的差异。结果表明: 1)围填海对水鸟的种类组成具有显著的影响, 围垦区雁鸭类水鸟的种类和数量显著高于未围垦区。土地利用类型的改变对水鸟的种类数具有显著影响, 围填海对芦苇和盐田的水鸟种类数量影响显著; 2)围填海造成土地利用类型的改变对水鸟的 Shannon-Wiener 指数具有显著的影响, 其中围垦区鱼塘的 Shannon-Wiener 指数显著高于未围垦区; 3)未围垦区碱蓬生境水鸟多度最大, 围垦区芦苇生境水鸟多度最大, 围填海造成的生境类型的改变对鹳类、鹤类、鸻鹬类、雁鸭类水鸟的栖息地选择具有较大影响。结果强调围垦后生境的可利用性和人为干扰大小决定了水鸟的群落结构和空间分布。     

陕西省黄河中游湿地冬季鸭科鸟类群落结构

2002～2007年冬季,对黄河中游湿地4种典型生境包括滩涂、人工渔塘、芦苇沼泽和莲池中的鸭科鸟类群落进行了调查.共记录到鸭科鸟类7属20种,采用频率指数法确定的优势种为斑嘴鸭、绿翅鸭、赤膀鸭、绿头鸭、普通秋沙鸭,其数量之和占总数量的65.6%.对4种不同生境的物种多样性、丰富度、均匀度、优势度进行分析,结果表明芦苇沼泽的多样性和丰富度指数最高,莲池的多样性和丰富度指数最低.人类活动引起的隐蔽场所和食物资源的变化是造成分布差异的主要原因.     

湖北武汉发现小美洲黑雁

正2015年11月22日,在湖北省武汉市东西湖区府河柏泉段(30°45′10″N,114°9′15″E)观察并拍摄到小美洲黑雁(Branta hutchinsii)1只(图1),隶属于雁形目鸭科黑雁属。该雁所发现之处,为长江一级支流——府河流经武汉柏泉的河段,该河段夏季被高水位所淹,冬季水位降低后,露出草滩,河道则因人为挖筑的堤岸而形成一个面积数百亩的开阔水面,中间有若干泥土堆积而成的小岛。同域分布有豆雁(Anser fabalis)、灰雁(A.anser)、绿头     

上海市南汇东滩围垦后海岸带湿地冬春季水鸟生境选择

2009年12月-2010年5月,对上海市南汇东滩围垦后城市湖泊湿地、实验修复湿地、抛荒湿地等三类人工湿地冬季雁鸭类群落和春季鸻鹬类群落展开调查,并对雁鸭类和鸻鹬类群落特征与相应生境因子进行相关分析.结果显示:三类湿地雁鸭类的种类无显著差异,但密度有显著差异:实验修复湿地是抛荒湿地的3.77倍,是城市湖泊湿地的6.03倍.鸻鹬类种类和密度:实验修复湿地分别是抛荒湿地的2.88和5.70倍.两者种类和密度差异均极显著.雁鸭类种类、密度、Shannon-Wiener多样性指数(H')与明水面面积显著正相关;种类、H'与植被面积显著负相关;种类、密度、H'均匀度与植被盖度显著负相关;H'与平均水位显著正相关.鸻鹬类种类、密度均与裸露浅滩面积显著正相关.建议对已围垦土地的利用以大中型鱼蟹塘、水田为主,以提供足够的明水面给越冬的雁鸭类栖息.通过割除植被等方法在春季提供一定的裸露浅滩面积供迁徙的鸻鹬类栖息.     

东海栉水母(Ctenophora)生态特征

根据1997~2000年东海23°30′~33°00′N、118°30′~128°00′E海域4个季节海洋调查资料,对东海栉水母数量变化和地理分布特征作了探讨。结果表明,东海栉水母平均丰度秋季(6.3 ind.(100m3)-1)>春季(1.6 ind.(100 m3)-1)>冬季(1.4 ind.(100 m3)-1)>夏季(0.6 ind.(100 m3)-1)。调查海域鉴定到种的栉水母共有6种,其中球型侧腕水母(Pleurobrachia globosa)是东海的主要种类;掌状风球水母(Hormiphora palnata)和瓜水母(Beroe cucumis)是常见种;带水母(Cestumsp.)是次常见种;蝶水母(Ocyropsis crystalline)和卵型瓜水母(Beroe avata)是稀有种。东海栉水母系暖水性浮游动物类群,其数量变化与东海暖流势力活动过程中的携带有密切的联系。球型侧腕水母分布较为广泛,是适应环境能力较强的种类;掌状风球水母、蝶水母和卵型瓜水母相反,仅适应有限的环境;瓜水母和带水母适应能力介于以上两类栉水母之间。     

Race and Racism in America and in Anthropology

Race in North America: Origin and Evolution of a Worldview . Audrey Smedley
Anthropology and Race . Eugenia Shanklin     

Degradation and conversion of somatostatin in normal and diabetic rats in vivo and in vitro

Plasma somatostatin-like immunoreactivity in the portal and jugular veins of streptozotocin diabetic rats was compared with that in normal control rats. In the diabetic group, somatostatin levels in the portal (p less than 0.05) and jugular (p less than 0.01) veins were both elevated compared with those in the control group. Moreover, the degree of elevation was greater in the jugular vein than in the portal vein. To further investigate the role of the liver in the clearance of somatostatin-28 in vivo, 2 micrograms of somatostatin-28 was administered as a bolus into the external jugular vein of intact and functionally hepatectomized rats. The mean half-time of somatostatin-28 was significantly longer in intact diabetic rats than in controls (p less than 0.05). The functional hepatectomy did not cause a significant difference in the half-time in diabetic rats but made it longer in control rats. These results suggest that the longer half-time of somatostatin-28 in diabetic rats in vivo is due to its slower hepatic clearance. The hepatic clearance of somatostatin-28 and somatostatin-14 was further studied in vitro using a recirculating liver perfusion method. The hepatic clearance of 1.2 nM of either somatostatin-28 or somatostatin-14 was significantly lower in diabetic rats than in controls (p less than 0.01). This indicates that elevated plasma somatostatin levels in diabetic rats are caused at least in part by decreased hepatic clearance of somatostatin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electroejaculation in chimpanzees and gorillas and artificial insemination in chimpanzees

Electroejaculation was performed in 3 chimpanzees, 1 pygmy chimpanzee, and 2 gorillas with an instrument that delivers a modified sine wave current with a frequency of 24 Hz. The current stimuli were applied by a rectal probe with longitudinal electrodes. The electrical parameters varied from 6 to 12 V and from 30 to 40 mA for response of erection and lay between 8 and 18 V and between 40 and 145 mA during semen emission. Eleven chimpanzee semen samples showed the following data (x ± SD): total volume 1.9 ± 1.3 ml, volume of the liquid fraction 0.3 ± 0.2 ml, spermatozoa per ejaculate 743 ± 376 × 10⁶, sperm motility 52.7 ± 9.6%, morphologically abnormal spermatozoa 12.2 ± 7.5%. From an adult gorilla, three semen samples were collected, in each case without spermatozoa. The electrostimulation of a 6-year-old gorilla led to an erection, but not to semen emission. Three female chimpanzees were inseminated with fresh or frozen semen, each of them within three different estrous cycles. None of these inseminations led to a pregnancy.     

Advances in purine and pyrimidine metabolism in health and diseases

ABSTRACT

In June, 2015, the Purine and Pyrimidine Society organized the 16th biennial symposium on Purine and Pyrimidine metabolism at the Faculty House of Columbia University, New York City. This exciting meeting focused on these important molecules, new developments in inborn errors of metabolism; therapeutic analogs. In addition, the biochemistry of mammalian and non-mammalian systems were discussed. Due to significant advances in molecular medicine, the boundaries between clinical and basic sciences have merged into exciting translational research, of which a small portion was highlighted in the presymposium.     

Trajectories and Constraints in Brain Evolution in Primates and Cetaceans

A negative allometric relationship between body mass (BM) and brain size (BS) can be observed for many vertebrate groups. In the past decades, researchers have proposed several hypotheses to explain this finding, but none is definitive and some are possibly not mutually exclusive. Certain species diverge markedly (positively or negatively) from the mean of the ratio BM/BS expected for a particular taxonomic group. It is possible to define encephalization quotient (EQ) as the ratio between the actual BS and the expected brain size. Several cetacean species show higher EQs compared to all primates, except modern humans. The process that led to big brains in primates and cetaceans produced different trajectories, as shown by the organizational differences observed in every encephalic district (e.g., the cortex). However, these two groups both convergently developed complex cognitive abilities. The comparative study on the trajectories through which the encephalization process has independently evolved in primates and cetaceans allows a critical appraisal of the causes, the time and the mode of quantitative and qualitative development of the brain in our species and in the hominid evolutionary lineage.     

Variation in infectivity and aggressiveness in space and time in wild host-pathogen systems: causes and consequences

Variation in host resistance and in the ability of pathogens to infect and grow (i.e. pathogenicity) is important as it provides the raw material for antagonistic (co)evolution and therefore underlies risks of disease spread, disease evolution and host shifts. Moreover, the distribution of this variation in space and time may inform us about the mode of coevolutionary selection (arms race vs. fluctuating selection dynamics) and the relative roles of G × G interactions, gene flow, selection and genetic drift in shaping coevolutionary processes. Although variation in host resistance has recently been reviewed, little is known about overall patterns in the frequency and scale of variation in pathogenicity, particularly in natural systems. Using 48 studies from 30 distinct host–pathogen systems, this review demonstrates that variation in pathogenicity is ubiquitous across multiple spatial and temporal scales. Quantitative analysis of a subset of extensively studied plant–pathogen systems shows that the magnitude of within‐population variation in pathogenicity is large relative to among‐population variation and that the distribution of pathogenicity partly mirrors the distribution of host resistance. At least part of the variation in pathogenicity found at a given spatial scale is adaptive, as evidenced by studies that have examined local adaptation at scales ranging from single hosts through metapopulations to entire continents and – to a lesser extent – by comparisons of pathogenicity with neutral genetic variation. Together, these results support coevolutionary selection through fluctuating selection dynamics. We end by outlining several promising directions for future research.     

MPD and DNA Bending in Crystals and in Solution

Bending of 15 to 24° is observed within crystal structures ofB-DNA duplexes, is strongly sequence-dependent, and exhibits no correlation with the concentration of MPD (2-methyl-2,4-pentanediol) in the crystallizing solution. Two types of bends are observed: facultative bends or flexible hinges at junctions between regions of G·C and A·T base-pairs, and a persistent and almost obligatory bend at the center of the sequence R-G-C-Y. Only A-tracts are characteristically straight and unbent in every crystal structure examined to date. A detailed examination of normal vector plots for individual strands of a double helix provides an explanation, in terms of the stacking properties of guanine and adenine bases. The effect of high MPD concentrations, in both solution and crystal, is to decrease local bending somewhat without removing it altogether. MPD gel retardation experiments provide no basis for choosing among the three models that seek to explain macroscopic curvature of DNA by means of microscopic bending: junction bending, bent A-tracts, or bent general- sequence DNA. Crystallographic data on the straightness of A-tracts, the bendability of non-A sequences, and the identity of inclination angles in A-tract and non-A-tractB-DNA support only the general-sequence bending model. The pre-melting transition observed in A-tract DNA probably represents a relaxation of stiff adenine stacks to a flexible conformation more typical of general-sequence DNA.