禽致病性大肠埃希菌强毒力岛（HPI）全岛缺失株的构建

目的构建大肠埃希菌强毒力岛（HPI）全岛缺失突变株,为进一步评价大肠埃希菌HPI的功能打下基础。方法根据已知大肠埃希菌HPI基因序列设计PCR敲除引物,引物5′端有50 bp的拟敲除基因的同源臂,3′端为扩增引物,以pKD3为模板,扩增两侧含FRT位点的氯霉素抗性基因,利用pKD46的λ重组系统替换E.coli ZL基因组上的毒力岛全岛基因,再利用表达Flp重组酶的质粒pCP20,可将FRT位点之间的氯霉素抗性基因删除,用鉴定引物进行鉴定并测序。结果构建的全岛缺失株与预期一致。结论成功构建了禽致病性大肠埃希菌强毒力岛（HPI）全岛缺失突变株。     

Temperature dependence of predation depends on the relative performance of predators and prey

The temperature dependence of predation rates is a key issue for understanding and predicting the responses of ecosystems to climate change. Using a simple mechanistic model, we demonstrate that differences in the relative performances of predator and prey can cause strong threshold effects in the temperature dependence of attack rates. Empirical data on the attack rate of northern pike (Esox lucius) feeding on brown trout (Salmo trutta) confirm this result. Attack rates fell sharply below a threshold temperature of +11°C, which corresponded to a shift in relative performance of pike and brown trout with respect to maximum attack and escape swimming speeds. The average attack speed of pike was an order of magnitude lower than the escape speed of brown trout at 5°C, but approximately equal at temperatures above 11°C. Thresholds in the temperature dependence of ecological rates can create tipping points in the responses of ecosystems to increasing temperatures. Thus, identifying thresholds is crucial when predicting future effects of climate warming.     

上海郊区冬夏季鸟类群落特征比较

2000年冬季和2001年夏季对上海郊区三种典型生境(农田居民区、湿地滩涂和丘陵林地)鸟类分别进行了调查,共记录到鸟类96种,隶属14目29科。本文重点探讨了冬夏两季鸟类群落的多样性、均匀度、优势度、生物量、重要值、种间相通机率、食性等群落特征。研究结果表明,上海郊区冬季鸟类种类、密度、多样性和生物量都明显高于夏季,而优势度则夏季高于冬季。不同生境中,湿地鸟类多样性和均匀度均最高,优势度农田居民区最高。密度冬季湿地最大,夏季农田居民区最大。改善环境的自然性、增加空间异质性、扩大保护区面积和减少人为干扰等可使鸟类群落的多样性和密度增加。     

Habitat-specific predation susceptibilities of a littoral rotifer to two invertebrate predators

The rotifer Euchlanis dilatata lives associated with submerged vegetation in the littoral zone of freshwater lakes and ponds. I assessed habitat-specific predation susceptibilities for this rotifer in the presence of three aquatic macrophytes (Myriophyllum exalbescens, Elodea canadensis, and Ceratophyllum demersum) and two predators (damselfly nymphs — Enallagma carunculata; and cnidarians — Hydra). Rotifer survival was greatest on Myriophyllum in the presence of both predators. Conversely, the presence of the other macrophyte species actually increase rotifer suspectibility to predation by damselfly nymphs. I also manipulated plant structural complexity. As predicted, decreasing the relative complexity of each plant resulted in lower rotifer survival.     

Demography and life history of free-rangingPropithecus diadema edwardsi in ranomafana national park,madagascar

I conducted the first long- term study of the life history patterns of Propithecus diadema edwardsi—Milne- Edward’s sifaka— in the rain forests of southeastern Madagascar, beginning in 1986. I report behavioral observations on a total of 33 individuals from three groups over a 9- year span. We captured,marked, and released 21 individuals. Individual group size ranged from three to nine sifakas. Two breeding females lived in groups I and II until 1993. A newly formed group (III) had one breeding female. Age at first reproduction is 4 years for females and 5 years for males. Gestation length is 179 days (n =2). Most births occurred in June (n = 17), but infants were also born in May (n = 2) and July (n =2). Nine of 21 (43%) infants born died before the age of 1 year, and 15 (67%) died before the age of reproduction. One female bred in her natal group after the death of the resident male and the immigration of an adult male. Another two females disappeared at 4 and 5 years of age;they could have emigrated or died. All 5- to- 6- year- old males (n = 4) have emigrated from their natal groups to adjacent groups. Two have committed infanticide. Five or more individuals were killed by Cryptoprocta ferox.Despite high mortality and offspring dispersal, the number of individuals in the two main groups remained nearly the same over the 9- year study.     

Influence of the red fox (<Emphasis Type="Italic">Vulpes vulpes</Emphasis>, Linnaeus 1758) on the distribution and number of breeding birds in an intensively used farmland

This study tested the hypothesis that small birds at their nest sites avoid areas around dens of the red fox (Vulpes vulpes, Linneaus 1758) in an intensively used farmland. Birds were counted at 18 points (radius 100m) located near dens, as well as at 18 control points that were located at least 600m away from the nearest den. These two types of points did not differ with respect to the number of recorded bird species. However, a negative effect of the proximity of fox dens on the total density of the bird community was observed. This effect was also recorded for the most abundant bird species, the skylark (Alauda arvensis, Linneaus 1758). In agreement with our expectations, these results indicate a negative impact of fox presence on a breeding bird community in an open farmland.     

Regulation of Rotifer Community by Predation of Cyclops vicinus (Copepoda) in the Římov Reservoir in Spring

The structuring role and predation impact of Cyclops vicinus on the rotifer community was studied using in situ enclosure experiments in Římov Reservoir during the spring of 2000. Seasonal changes in abundance and birth rates of the rotifer species Synchaeta lakowitziana , Polyarthra spp., Keratella cochlearis and Kellicottia longispina were related to predation pressure, i.e. selectivity and cropping rates of C. vicinus . All four rotifer species were found to be consumed by C. vicinus whose predation rates showed a marked succession through the spring period and corresponded to changes in the relative abundance of the pelagic species. The highest predation rates exhibited by C. vicinus were on Synchaeta lakowitziana and Polyarthra spp., being 11.3 and 6.4 ind Cyclops ^–1 day^–1 respectively. The activity of the predator switched among three types of preferred food during the spring period. The most preferred, Synchaeta, was replaced by Polyarthra after Synchaeta became extinct and these species were replaced by Keratella when both soft‐bodied forms were not available in sufficient quantities. Loricated species (K. cochlearis and K. longispina) were consumed at a slower rate. We calculated the proportion of rotifer production cropped day^–1 in order to estimate the predation impact of C. vicinus , which ranged from 11.6 to more than 100% over time and rotifer species. This shows that relative predation impact can be high not only on species most strongly selected, but also on species which are not selected. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

禽流感病毒H9N2血凝素基因和神经氨酸酶因在大肠杆菌中的表达

克隆、表达和鉴定禽流感病毒H9N2 HA,NA基因序列,为制备抗体和基因工程疫苗打下基础。在成功克隆禽流感病毒H9N2全长HA、NA基因并测序的基础上,将部分基因序列克隆到表达载体pET32a(+)上,全基因序列克隆到表达载体pGEX4T-1上,构建了重组表达质粒pET32a(+)/HA(截短)、pET32a(+)/NA(截短)、pGEX4T-1/HA、pGEX4T-1/NA,转化大肠杆菌BL21/rosetta,IPTG诱导表达,利用Ni2+亲和层析柱和GSTrap4B亲和层析柱对重组蛋白进行纯化,并用Western Blotting和ELISA方法检测其抗原性。结果重组蛋白在大肠杆菌中可以高效表达,SDS-PAGE显示其相对分子质量与预计大小一致。ELISA和Western Blotting实验证实,重组蛋白具有良好的抗原性。本研究成功克隆和表达了禽流感病毒H9N2 HA、NA基因序列。为禽流感病毒H9N2诊断试剂和疫苗的开发等进一步的研究奠定了基础。     

二种萤火虫幼虫捕食行为及头部功能性结构观察比较

对短角窗萤Diaphanes sp.和胸窗萤Pyrocoelia pectoralis Olivier幼虫的捕食行为进行观察。发现短角窗萤捕食蚯蚓而胸窗萤则捕食蜗牛。利用扫描电镜对短角窗萤和胸窗萤幼虫的头部及口器进行观察比较。发现2种幼虫均具有1对侧单眼,1对发达的、左右对称的3节触角。2种幼虫口器非常发达,具1对锋利的、中空的镰刀状上颚,1对下颚须,1对下唇须,1对内颚叶。2种萤火虫口器最具特别的结构在于:短角窗萤上颚的2/3处内侧着生1个球形结构,上面着生1层齿状结构,而胸窗萤则在上颚基部内侧弯曲成齿状突起。     

Spatial explicit demography: The effects habitat patch isolation have on vole matrilines

Populations of many species are spatially structured in matrilines, and their dynamics may be determined by matriline specific demographic processes. We examined whether the isolation of habitat patches (i.e. interpatch distance) affected the demography of matrilines in 14 experimentally fragmented populations of the root vole. Matrilines inhabiting the most isolated patches decreased in size over the breeding season, while matrilines in less isolated patches increased. The survival rate of adult females was the main factor underlying the variation in growth rates among matrilines. Low survival when patches were isolated seemed to be due to long-distance interpatch movements exposing females to increased predation rate.
The differential success of matrilines in patchy populations with variable interpatch distances acted to decrease the matrilineal diversity at the population level. Furthermore, isolated patches may function as sinks. Thus spatially explicit landscape features may affect both population demography and genetics.