Holographic quantitative structure-activity relationship for prediction acute toxicity of benzene derivatives to the guppy(poecilia reticulata)

Holographic quantitative structure activity relationship(HQSAR) is an emerging QSAR technique with the combined application of molecular hologram, which encoded the frequency of occurrence of various molecular fragment types, and the subsequent partial least squares(PLS) regression analysis. In this paper, the acute toxicity data to the guppy( poecilia reticulata) for a series of 56 substituted benzenes, phenols, aromatic amines and nitro aromatics were subjected and this resulted in a model with a high predictive ability. The influence of fragment size and fragment distinction parameters on the quality of HQSAR model was investigated. The robustness and predictive ability of the model were also validated by leave one out (LOO) cross validation procedure and external testing data set.

Cloning and Expression Analysis of a Prion Protein Encoding Gene in Guppy (Poecilia reticulata)

The full length cDNA of a prion protein (PrP) encoding gene of guppy (Poecilia reticulata) and the corresponding ge-nomic DNA were cloned. The cDNA was 2245 bp in length and contained an open reading frame (ORF) of 1545 bp encoding a pro-tein of 515 amino acids,which held all typical structural characteristics of the functional PrP. The cloned genomic DNA fragment corresponding to the cDNA was 3720 bp in length,consisting of 2 introns and 2 exons. The 5’ untranslated region of cDNA origi-nated from the 2 exons,while the ORF originated from the second exon. Although the gene was transcribed in diverse tissues in-cluding brain,eye,liver,intestine,muscle and tail,its transcript was most abundant in the brain. In addition,the transcription of the gene was enhanced by 5 salinity,implying that it was associated with the response of guppy to saline stress.

No association between brain size and male sexual behavior in the guppy

Animal behavior is remarkably variable at all taxonomic levels. Over the last decades, research on animal behavior has focused on understanding ultimate processes. Yet, it has progressively become more evident that to fully understand beha- vioral variation, ultimate explanations need to be complemented with proximate ones. In particular, the mechanisms generating variation in sexual behavior remain an open question. Variation in aspects of brain morphology has been suggested as a plausible mechanism underlying this variation. However, our knowledge of this potential association is based almost exclusively on com- parative analyses. Experimental studies are needed to establish causality and bridge the gap between micro- and macroevolutio- nary mechanisms concerning the link between brain and sexual behavior. We used male guppies that had been artificially selected for large or small relative brain size to study this association. We paired males with females and scored the full known set of male and female sexual behaviors described in guppies. We found several previously demonstrated associations between male traits, male behavior and female behavior. Females responded more strongly towards males that courted more and males with more orange coloration. Also, larger males and males with less conspicuous coloration attempted more coerced copulations. However, courting, frequency of coerced copulation attempts, total intensity of sexual behavior, and female response did not differ between large- and small-brained males. Our data suggest that relative brain size is an unlikely mechanism underlying variation in sexual behavior of the male guppy. We discuss these findings in the context of the conditions under which relative brain size might affect male sexual behavior .

In vitro culture of embryonic hearts from guppy fish (Poecilia reticulata)

Forty embryonic hearts were taken out by anatomical needle from denuded embryos of the ovovivipar-ity guppy fish that were dechorioned by mechanic method or by trypsin digestion, and were in vitro cultured. In the cultured hearts, 80% have maintained beating in vitro for 4 weeks, and the longest record for beating was 142 d. Owing to fish embryo transparency, beating frequency and blood color changes are easily viewed from the embryonic hearts under a dissecting microscope. The current study established the in vitro culture method of embryonic hearts in guppy fish, which can be used as a model for the study of heart and cardiovascular system in vertebrates.

土壤磷素分级方法研究评述

讨论了土壤磷素形态和有机磷有效性研究进展,分析了传统土壤磷素分级方法局限性,综述了土壤磷素分级方法的研究进展,特别详细地描述了Hedley法和Guppy法。

Gradients in predation risk in a tropical river system

The importance of predation risk as a key driver of evolutionary change is exemplified by the Northern Range in Trinidad, where research on guppies living in multiple parallel streams has pro- vided invaluable insights into the process of evolution by natural selection. Although Trinidadian guppies are now a textbook example of evolution in action, studies have generally categorized predation as a dichotomous variable, representing high or low risk. Yet, ecologists appreciate that community structure and the attendant predation risk vary substantially over space and time. Here, we use data from a longitudinal study of fish assemblages at 16 different sites in the Northern Range to quantify temporal and spatial variation in predation risk. Specifically we ask： 1） Is there evidence for a gradient in predation risk？ 2） Does the ranking of sites （by risk） change with the defi- nition of the predator community （in terms of species composition and abundance currency）, and 3） Are site rankings consistent over time？ We find compelling evidence that sites lie along a contin- uum of risk. However, site rankings along this gradient depend on how predation is quantified in terms of the species considered to be predators and the abundance currency is used. Nonetheless, for a given categorization and currency, rankings are relatively consistent over time. Our study sug- gests that consideration of predation gradients will lead to a more nuanced understanding of the role of predation risk in behavioral and evolutionary ecology. It also emphasizes the need to justify and report the definition of predation risk being used.

拍卖或招投标市场上横向合并的单边效应及其识别——对甲骨文和仁科公司合并的案例分析

识别横向合并中的单边效应是各国反垄断审查的重点内容。本文通过研究关联价值模型下拍卖或招投标市场上横向合并的单边效应,得出了单边效应产生的充分必要条件,并将差异化产品市场上单边效应的UPP(价格上涨压力测试法)思想推广到拍卖或招投标市场上。在此基础上,利用改进的GUPPI(涨价压力总指数)对甲骨文仁科合并案进行分析,结果与欧美反垄断机构测算出的结果基本一致,即该起合并会产生单边效应。本文提出,GUPPI指数可以作为快速有效的初步筛选工具应用到拍卖或招投标市场中的横向合并审查,中国反垄断执法机构对拍卖或招投标市场中的合并审查可采用类似方法。

Evaluations of larvicidal activity of medicinal plant extracts to Aedes aegypti （Diptera： Culicidae） and other effects on a non target fish

A preliminary study was conducted to investigate the effects of the extracts of 112 medicinal plant species, collected from the southern part of Thailand, on Aedes aegypti. Studies on larvicidal properties of plant extracts against the fourth instar larvae revealed that extracts of 14 species showed evidence of larvicidal activity. Eight out of the 14 plant species showed 100% mosquito larvae mortality. The LC50 values were less than 100μg/mL （4.1μg/ mL-89.4μg/mL）. Six plant species were comparatively more effective against the fourth instar larvae at very low concentrations. These extracts demonstrated no or very low toxicity to guppy fish （Poecilia reticulata）, which was selected to represent most common non-target organism found in habitats ofAe. aegypti, at concentrations active to mosquito larvae. Three medicinal plants with promising larvicidal activity, having LC50 and LC50 values being 4.1 and 16.4 μg/mL for Mammea siamensis, 20.2 and 34.7 μg/mL forAnethum graveolens and 67.4 and 110.3μg/mL forAnnona muricata, respectively, were used to study the impact of the extracts on the life cycle ofAe. aegypti. These plants affected pupal and adult mortality and also affected the reproductive potential of surviving adults by reducing the number of eggs laid and the percentage of egg hatchability. When each larval stage was treated with successive extracts at the LC50 value, the first instar larvae were found to be very susceptible to A. muricata and the second instar larvae were found to be susceptible to A. graveolens, while the third and fourth instar larvae were found to be susceptible to M. siamensis. These extracts delayed larval development and inhibited adult emergence and had no adverse effects on P. reticulata at LC50 and LC50 values, except for the M. siamensis extract at its LC50 value.

横向并购中单边效应的经济分析

评估横向并购的竞争影响需要综合考量多方面因素,其中对单边效应的评估是其中的重点和难点,往往需要经济分析的支撑。本文将总结评估单边效应的基本思路,详细阐述合并模拟、分流比和综合涨价压力指数(GUPPI)三种当今评估单边效应的新型经济分析工具及其适用局限性,并结合我国的实践经验分析上述单边效应的经济分析工具在经营者集中反垄断审查中的适用。

Male mate choice in livebearing fishes： an overview

Although the majority of studies on mate choice focus on female mate choice, there is growing recognition of the role of male mate choice too. Male mate choice is tightly linked to 2 other phenomena： female competition for males and ornamentation in females. In the current article, I review the existing literature on this in a group of fishes, Poeciliidae. In this group, male mate choice appears to be based on differences in female quality, especially female size, which is a proxy for fecundity. Some males also have to choose between heterospecific and conspecific females in the unusual mating system of the Amazon molly. In this case, they typically show a preference for conspecific females. Whereas male mate choice is relatively well documented for this family, female ornamentation and female competition are not.

Sender and receiver experience alters the response of fish to disturbance cues

Predation is a pervasive selection pressure,shaping morphological,physiological,and behavioral phenotypes of prey species.Recent studies have begun to examine how the effects of individual experience with predation risk shapes the use of publicly available risk assessment cues.Here,we investigated the effects of prior predation risk experience on disturbance cue production and use by Trinidadian guppies Poecilia reticulata under laboratory conditions.In our first experiment,we demonstrate that the response of guppies from a high predation population(Lopinot River)was dependent upon the source of disturbance cue senders(high vs.low predation populations).However,guppies collected from a low predation site(Upper Aripo River)exhibited similar responses to disturbance cues,regardless of the sender population.In our second experiment,we used laboratory strain guppies exposed to high versus low background risk conditions.Our results show an analogous response patterns as shown for our first experiment.Guppies exposed to high background risk conditions exhibited stronger responses to the disturbance cues collected from senders exposed to high(vs.low)risk conditions and guppies exposed to low risk conditions were not influenced by sender experience.Combined,our results suggest that experience with background predation risk significantly impacts both the production of and response to disturbance cues in guppies.

虚拟无线电I/O接口实现的一种方案

文章在虚拟无线电概念的基础上 ,结合开发的GuPPI(generalpurposePCII/O)卡以及相应的低端数据处理应用程序 ,给出了一种虚拟无线电I/O的接口方案 ,详细地阐述了其实现的思路。该方案以通用计算机为硬件平台 ,以Windows 9x为软件平台 ;GuPPI卡采用了AMCC公司的S5 933PCI主从控制器 ,低端数据处理应用程序利用了Vireo公司的VtoolsD和VisualC + +来实现。

Local predation risk shapes spatial and foraging neophobia patterns in Trinidadian guppies

The ＂dangerous niche＂ hypothesis posits that neophobia functions to reduce the cost of habitat use among animals exposed to unknown risks. For example, more dangerous foraging or higher competi- tion may lead to increased spatial neophobia. Likewise, elevated ambient predation threats have been shown to induce phenotypically plastic neophobic predator avoidance. In both cases, neophobia is argued to reduce the cost of living associated with ecological uncertainty. Here, we test the hypothesis that ambient predation shapes both neophobic predator avoidance and spatial and foraging neophobia in Trinidadian guppies. Guppies were exposed to a novel foraging arena paired with a known cue （conspecific alarm cue）, a novel cue （lemon odor）, or a stream water control in three streams differing in ambient predation risk. We demonstrate that guppies from a high-predation-risk stream exhibited risk-averse foraging patterns regardless of the chemical stimulus presented （high spatial neophobia） and that those from a low-predation-risk stream were only risk-averse when the foraging arenas were paired with conspecific alarm cue （lower spatial neophobia）. Those tested in the intermediate- predation-risk stream were consistently intermediate to the high-risk vs. low-risk populations. Our study suggests that ambient predation risk shapes both neophobic predator avoidance and space-use pat- terns and that neophobia may function as a ＂generalized＂ response to ecological uncertainty.