纳米Cu2O原药与悬浮液对菜瓜灰霉病菌的抑制作用

为比较纳米 Cu2O原药与悬浮液对菜瓜灰霉病菌的抑制作用，研究采用含药培养基法进行了毒力测定。试验结果表明：同一质量浓度的纳米 Cu2O悬浮液对菜瓜灰霉病菌的抑菌效果明显优于纳米 Cu2O原药，抑制作用与质量浓度呈正相关；毒力回归方程的相关系数分别为0.8922和0.9961，纳米 Cu2O原药与悬浮液对菜瓜灰霉病菌的有效中浓度 EC50分别为3948.9和167.9 mg/kg.因此纳米Cu2O原药对菜瓜灰霉病菌有一定的抑制作用，而纳米Cu2O悬浮液对菜瓜灰霉病菌的抑制作用非常明显。     

Patterns of mortality in a cold-climate population of garter snakes (Thamnophis sirtalis parietalis)

The causes, magnitude and phenotypic determinants of mortality are central features of population demography. Although critical to effective conservation planning, these attributes remain poorly understood for most wild vertebrates. Exceptionally dense aggregations of garter snakes (Thamnophis sirtalis parietalis) in and around communal overwintering dens in central Manitoba provide an exceptional opportunity to enumerate these factors. Over the course of long-term field studies we obtained data on mortality of snakes in autumn as they migrated back from their summer ranges, and in winter during and after their entry into the underground dens. Some mortality sources were affected by a snake's phenotype: for example, snakes killed by motor vehicles were smaller, on average, than surviving snakes. However, two major episodes of mortality at the dens themselves (freezing during midwinter due to atypically light snow cover; and drowning due to flooding after heavy rains late in autumn) were essentially random with respect to phenotype. Mark-recapture estimates suggest that the winterkill event eliminated >60,000 snakes, comprising almost the entire populations of the three largest dens. Although such events are cryptic because the bodies of frozen animals remain underground, they are of much greater magnitude than overt mortality sources for active snakes (roadkills, predation, etc.). Thus, relatively minor habitat manipulations around the dens may contribute more to conservation of these populations than would extensive efforts to protect active snakes during their spring and autumn migrations.     

Sperm motility parameters to evaluate the seminal quality of Boa constrictor occidentalis, a threatened snake species

Semen quality analysis constitutes a powerful tool to evaluate the fertility potential of males in threatened species. The Argentine boa constrictor or lampalagua (Boa constrictor occidentalis) is a threatened snake species and has been included in Appendix I of CITES. The objective of this work is to characterize the sperm of B. c. occidentalis on the bases of dynamic parameters to improve this species conservation. Dynamic parameters were measured in sperm samples using videomicroscopy and image analysis software. The sperm population showed a high degree of heterogeneity in velocity parameter values and 95% of the cells showed a linear pattern of movement. Studies in other species indicate that the number of motile spermatozoa and their movement speed is directly correlated with fertilization success. This work will help to establish basic parameter values for the evaluation of the reproductive potential of populations of B. c. occidentalis and to resolve questions referred to its reproductive strategies.     

Cytb、12SrRNA基因进化速度对构建系统进化树的影响

[目的]论证线粒体Cytb和12SrRNA基因不同进化速率影响构建的系统树拓扑结构。[方法]从GenBank下载了蛇亚目12科15种蛇线粒体全序列,提取Cytb和12SrRNA基因序列,选用GTR＋I＋G核苷酸替代模型,基于最大似然法,用PAUP4.0软件分别构建2个基因的系统关系树。[结果]在选用相同的软件、建树方法和研究物种的情况下,构建的系统树拓扑结构差异主要是因为线粒体Cytb和12SrRNA基因进化速率不同产生的。[结论]在分子系统进化研究中,要针对不同的研究物种和研究目的,选择合适的基因构建系统进化树。     

Plasma insulin-like growth factor-I concentrations in yearling chinook salmon (Oncorhynchus tshawytscha) migrating from the Snake River Basin, USA

During the parr-to-smolt transformation (smoltification) of juvenile salmonids, preadaptive changes in osmoregulatory and ionoregulatory ability are regulated in part by the growth hormone (GH)/insulin-like growth factor-I (IGF-I) axis. If food intake is sufficient, plasma IGF-I increases during smoltification. On the other hand, plasma IGF-I typically decreases in fasting fish and other vertebrate animals. Because food availability is limited for juvenile salmonids undertaking an extended 6- to 12-week springmigration to and through the Snake-Columbia River hydropower system (northwestern USA), IGF-I concentrations might be expected to decrease, potentially compromising seawater tolerance. To address this possibility,yearling chinook salmon Oncorhynchus tshawytscha reared in three Snake River Basin hatcheries were sampled before release and at two downstream dams. Dry masses ofmigrating fish either did not increase during themigration (in 2000, an average-flow year), or decreased significantly (in 2001, a low-flow year). In both years, plasma IGF-I levels were significantly higher (1.6-fold in 2000, 3.7-fold in 2001) for fish sampled at the last dam on the lower Columbia River than for fish sampled prior to release. Plasma IGF-I concentrations inmigrating fish may, nonetheless, have been nutritionally down-regulated to some degree, because plasma IGF-I concentrations in juvenile chinook salmon captured at a Snake River dam and transported to the laboratory increased in fed groups, but decreased in unfed groups. The ability ofmigrating smolts to maintain relatively elevated IGF-I levels despiteRestricted food intake and loss of body mass is likely related to smoltification-associated changes in hormonal balance.     

基于修正的Snake模型与特征对象法的多运动目标分割

在分析常规的运动目标分割算法的基础上，以计算简单、速度快、能精确提取运动目标为原则，提出了基于特征对象的运动目标分割算法，并将该法与修正的Snake模型结合进行了运动目标外廓的精确提取.分析和实验表明：该算法需要调整的参数少，计算简单，速度快，抗干扰能力强，可以有效地消除多帧间运动目标的遮挡，在多运动目标不重叠的情况下，能精确定位多运动目标的外轮廓.