复杂度脑电地形图研究

脑电地形图是近年脑电分析的热点之一。通过对各种复杂度算法的分析得出,近似熵由于所需要的时间序列长度较短,大大减少了脑电非平稳性所带来的困难,且无需粗粒化,在对生物医学信号的复杂度分析中有其一定的优点,采用近似熵对多道脑电信号的复杂度运算结果,通过空间插值,构建复杂性动态脑地形图,以便于观察大脑各部ＥＥＧ信号复杂度在同一时刻的相对强弱关系和这种关系随时间的变化。并通过对一些脑疾病患者脑电数据的分析,     

Parallel and nonparallel aspects of ecological, phenotypic, and genetic divergence across replicate population pairs of lake and stream stickleback

Parallel (or convergent) evolution provides strong evidence for a deterministic role of natural selection: similar phenotypes evolve when independent populations colonize similar environments. In reality, however, independent populations in similar environments always show some differences: some nonparallel evolution is present. It is therefore important to explicitly quantify the parallel and nonparallel aspects of trait variation, and to investigate the ecological and genetic explanations for each. We performed such an analysis for threespine stickleback (Gasterosteus aculeatus) populations inhabiting lake and stream habitats in six independent watersheds. Morphological traits differed in the degree to which lake-stream divergence was parallel across watersheds. Some aspects of this variation were correlated with ecological variables related to diet, presumably reflecting the strength and specifics of divergent selection. Furthermore, a genetic scan revealed some markers that diverged between lakes and streams in many of the watersheds and some that diverged in only a few watersheds. Moreover, some of the lake-stream divergence in genetic markers was associated within some of the lake-stream divergence in morphological traits. Our results suggest that parallel evolution, and deviations from it, are primarily the result of natural selection, which corresponds in only some respects to the dichotomous habitat classifications frequently used in such studies.     

Dendritic protein synthesis, synaptic plasticity, and memory

Considerable evidence suggests that the formation of long-term memories requires a critical period of new protein synthesis. Recently, the notion that some of these newly synthesized proteins originate through local translation in neuronal dendrites has gained some traction. Here, we review the experimental support for this idea and highlight some of the key questions outstanding in this area.     

A reappraisal of the terverticillate penicillia using biochemical, physiological and morphological features. III. An evaluation of pectinase and amylase isoenzymes for species characterization

Polyacrylamide gel electrophoresis of extracellular pectinase and amylase isozymes of 170 mainly terverticillate Penicillium strains was undertaken. The data were coded and subjected to numerical analysis. Variation in intensity of isozymes was observed in repeat analyses of some strains, although most were consistent. Variation was also observed between some representative strains of species. P. viridicatum was more variable than P. brevicompactum and P. hordei for intensity of pectinase activity. There was a correlation between the grouping of the strains on the basis of the isozymes and the species concepts only in some cases. The method proved useful for the identification of strains producing intense activity which provided clear patterns, for example, P. brevicompactum and P. chrysogenum and to a lesser extent P. solitum var. crustosum and P. hordei. The method was also exclusionary in that some species were restricted to a particular cluster or subcluster. Amylase patterns confirmed that strains referred to as single species are not all homogeneous genetically, and that some strains are not simply haploid homokaryons. The genetic heterogeneity of the strains explains some of the problems in the systematics of the terverticillate penicillia.     

转基因抗虫作物对非靶标昆虫的影响

转基因抗虫作物自 1996年被批准商业化种植以来 ,它的抗虫性和经济效益已得到了普遍肯定 ,同时 ,转基因抗虫作物对非靶标生物的影响 ,如转基因抗虫作物的长期种植 ,是否会导致次要害虫上升为主要害虫 ,是否会影响有益昆虫 ,包括重要经济昆虫、捕食性和寄生性天敌以及重要蝶类的种类及种群数量 ,已成为转基因抗虫作物生态风险评估的重要内容。一些研究结果表明 ,转基因抗虫作物在对靶标害虫有效控制的同时 ,一些对杀虫蛋白不敏感的非靶标害虫有加重危害的趋势 ,由于种植转基因抗虫作物 ,减少了化学农药的使用 ,客观上也使非靶标害虫种群数量上升 ,这对转基因抗虫作物害虫综合治理提出了新的要求。靶标害虫数量的减少直接影响了害虫天敌种群数量 ,靶标害虫取食转基因抗虫作物后发育迟缓 ,也间接影响了天敌昆虫的生长发育 ,转基因抗虫作物的花粉或花蜜是一些重要经济昆虫如蜜蜂、熊蜂和一些寄生蜂 ,甚至捕食性天敌的食物来源 ,或花粉飘落到一些鳞翅目昆虫如家蚕或重要蝶类昆虫的寄主植物上 ,直接或间接对这些昆虫造成一定影响。目前大多数研究表明转基因抗虫作物对非靶标昆虫 ,特别是对有益昆虫没有明显的不利影响 ,也有研究报道认为对某些有益昆虫有一定的不良影响。这为深入开展转基因抗虫作物的生态安全     

On the HIV Incubation Distribution Under AZT Treatment

Assuming some general models for the HIV epidemic, in this paper I derive the HIV incubation distributions under AZT treatment. It is shown that under some conditions, these probability distributions are mixtures of some generalized Gamma distributions and products of generalized Gamma distributions.     

Error catastrophe in and the evolution of the protein synthesizing machinery

The theory of the propagation of errors in the system of enzymes translating genetic information proposed earlier is developed further. It is shown that if initially for some of these enzymes the normal molecules are more than, for some less than, and for some equal to the erroneous ones, the evolution of the system can lead to many asymptotic conditions including error catastrophe and complete recovery from errors.     

Tools and collaborative environments for bioinformatics research

Advanced research requires intensive interaction among a multitude of actors, often possessing different expertise and usually working at a distance from each other. The field of collaborative research aims to establish suitable models and technologies to properly support these interactions. In this article, we first present the reasons for an interest of Bioinformatics in this context by also suggesting some research domains that could benefit from collaborative research. We then review the principles and some of the most relevant applications of social networking, with a special attention to networks supporting scientific collaboration, by also highlighting some critical issues, such as identification of users and standardization of formats. We then introduce some systems for collaborative document creation, including wiki systems and tools for ontology development, and review some of the most interesting biological wikis. We also review the principles of Collaborative Development Environments for software and show some examples in Bioinformatics. Finally, we present the principles and some examples of Learning Management Systems. In conclusion, we try to devise some of the goals to be achieved in the short term for the exploitation of these technologies.     

Mechanical aspects of cardiac development

Heart development depends on a dynamic interaction between genetic and epigenetic factors. This paper discusses some of the biomechanical processes that help shape the heart in the embryo. First, an overview is given of some of the critical events that occur during cardiac development. Next, mechanics and modeling strategies are discussed for the morphogenetic processes of cardiac tube formation, cardiac looping, myocardial trabeculation, septation, valve formation, and muscle-fiber alignment. Finally, some considerations for future work in this area are listed.     

正常人及不育者精子核DNA的定量研究

用流式细胞术,Feulgen显微分光光度法,荧光显微分光光度法测定正常人精子核DNA相对含量:结果表明,上述方法所测得的精子核DNA相对含量稳定,变化范围小。同时用Feulgen显微分光光度法测定不育者精子核DNA相对含量。显示不育者精子核DNA相对含量高于正常人,提示精子核DNA核蛋白复合物异常可能是某些男性不育症的原因。此项研究为诊断男性不育症提供了新方法,在男性学精子核分子研究方面提供了依据。     

A Web-based course of lectures in respiratory physiology

A complete course of respiratory physiology suitable for first-year medical and graduate students has been placed on the Web for our own students and for other educational institutions. There are several reasons for doing this. The first is that the modern-day student uses a variety of options for acquiring knowledge. These include attending lectures, reading texts, iPod downloads, and surfing the internet. This Web-based course is another option that may be preferable for some students. A second reason is that it is becoming increasingly difficult for some medical schools to find faculty members who are willing and able to teach the principles of respiratory physiology. This is a potentially serious problem because a sound knowledge of respiratory physiology will always be necessary for the intelligent practice of medicine. Schools with limited faculty may find it useful to use these Web-based lectures followed by a discussion session with students. Another reason is that some schools have moved away from systematic lectures to case-based discussions, with the possibility that students will not be exposed to some of the principles of respiratory physiology. The hope is that this comprehensive course of lectures will help students to assimilate this important material as the medical school curriculum continues to expand at a rapid rate.     

Novel techniques to establish new insect cell lines

Summary The success of insect cell culture is demonstrated by reports of over 500 established cell lines. While established procedures that can be used for developing new cell lines exist, these usually require some fine-tuning for various tissue sources. This paper attempts to depict some of the variations that can be applied.     

Panbiogeography of New Caledonia: a response to Heads (2008)

The definition of areas of endemism is one of the most important steps for historical biogeography. Here I review the dataset used by Heads (Journal of Biogeography, 2008, 35 , 2153–2175) for his panbiogeographical analysis of the New Caledonian biota. I highlight that some of the distribution data appear dubious (some localities should have been included while some others should have been deleted) when compared with current databases. In addition, some conclusions are not supported by the data themselves.     

第22种氨基酸和无义密码子的重新诠释

遗传密码字典的破译,通用性作为遗传密码的基本特点之一被人们认可.近年来的研究发现了一些例外.除线粒体使用一组密码子其含义有别于核基因之外,原先被认为仅用作终止信号的无义密码子在某些情况下可重新诠释,编码特定的氨基酸.在揭示了硒代半胱氨酸由UGA编码后,最近的研究表明,在某些古细菌和真细菌中,无义密码子UAG可重新诠释,编码组成蛋白质的第22种天然氨基酸——吡咯赖氨酸.     

肿瘤放化综合治疗中的靶向研究

放化疗综合应用是癌症治疗中的常用方法。研究表明,放化疗综合应用可以有效地控制杀伤肿瘤,但过程中对正常细胞的毒副作用严重制约着放化疗的剂量和疗效。如何在有效杀伤肿瘤细胞的同时减轻放化疗综合应用中对正常细胞的毒副作用已经成为探索更好的治疗策略的关键。随着研究的不断深入,各种相关的新药和新治疗思路层出不穷,比如针对肿瘤发生及代谢过程的靶向类新药、用于辐射增敏的新的基因靶点等都已进入研究者的视线。另外,近年来关于肿瘤细胞中药物转运蛋白的研究也为综合治疗靶点寻找提供了一定依据。本文根据当前研究现状,着重总结近年来放化疗综合治疗靶向研究在上述几方面的一些新进展。     

肿瘤放化综合治疗中的靶向研究

放化疗综合应用是癌症治疗中的常用方法。研究表明,放化疗综合应用可以有效地控制杀伤肿瘤,但过程中对正常细胞的毒副作用严重制约着放化疗的剂量和疗效。如何在有效杀伤肿瘤细胞的同时减轻放化疗综合应用中对正常细胞的毒副作用已经成为探索更好的治疗策略的关键。随着研究的不断深入,各种相关的新药和新治疗思路层出不穷,比如针对肿瘤发生及代谢过程的靶向类新药、用于辐射增敏的新的基因靶点等都已进入研究者的视线。另外,近年来关于肿瘤细胞中药物转运蛋白的研究也为综合治疗靶点寻找提供了一定依据。本文根据当前研究现状,着重总结近年来放化疗综合治疗靶向研究在上述几方面的一些新进展。     

Effects of boron-containing compounds in the fungal kingdom

BackgroundThe number of known boron-containing compounds (BCCs) is increasing due to their identification in nature and innovative synthesis procedures. Their effects on the fungal kingdom are interesting, and some of their mechanisms of action have recently been elucidated.MethodsIn this review, scientific reports from relevant chemistry and biomedical databases were collected and analyzed.ResultsIt is notable that several BCC actions in fungi induce social and economic benefits for humans. In fact, boric acid was traditionally used for multiple purposes, but some novel synthetic BCCs are effective antifungal agents, particularly in their action against pathogen species, and some were recently approved for use in humans. Moreover, most reports testing BCCs in fungal species suggest a limiting effect of these compounds on some vital reactions.ConclusionsNew BCCs have been synthesized and tested for innovative technological and biomedical emerging applications, and new interest is developing for discovering new strategic compounds that can act as environmental or wood protectors, as well as antimycotic agents that let us improve food acquisition and control some human infections.     

A practical guide to molecular dating

Molecular dating has now become a common tool for many biologists and considerable methodological improvements have been made over the last few years. However, the practice of estimating divergence times using molecular data is highly variable among researchers and it is not straightforward for a newcomer to the field to know how to start. Here I provide a brief overview of the current state-of-the-art of molecular dating practice. I review some of the important choices that must be made when conducting a divergence time analysis, including how to select and use calibrations and which relaxed clock model and program to use, with a focus on some practical aspects. I then provide some guidelines for the interpretation of results and briefly review some alternatives to molecular dating for obtaining divergence times. Last, I present some promising developments for the future of the field, related to the improvement of the calibration process.     

Functional diversity: back to basics and looking forward

Functional diversity is a component of biodiversity that generally concerns the range of things that organisms do in communities and ecosystems. Here, we review how functional diversity can explain and predict the impact of organisms on ecosystems and thereby provide a mechanistic link between the two. Critical points in developing predictive measures of functional diversity are the choice of functional traits with which organisms are distinguished, how the diversity of that trait information is summarized into a measure of functional diversity, and that the measures of functional diversity are validated through quantitative analyses and experimental tests. There is a vast amount of trait information available for plant species and a substantial amount for animals. Choosing which traits to include in a particular measure of functional diversity will depend on the specific aims of a particular study. Quantitative methods for choosing traits and for assigning weighting to traits are being developed, but need much more work before we can be confident about trait choice. The number of ways of measuring functional diversity is growing rapidly. We divide them into four main groups. The first, the number of functional groups or types, has significant problems and researchers are more frequently using measures that do not require species to be grouped. Of these, some measure diversity by summarizing distances between species in trait space, some by estimating the size of the dendrogram required to describe the difference, and some include information about species' abundances. We show some new and important differences between these, as well as what they indicate about the responses of assemblages to loss of individuals. There is good experimental and analytical evidence that functional diversity can provide a link between organisms and ecosystems but greater validation of measures is required. We suggest that non-significant results have a range of alternate explanations that do not necessarily contradict positive effects of functional diversity. Finally, we suggest areas for development of techniques used to measure functional diversity, highlight some exciting questions that are being addressed using ideas about functional diversity, and suggest some directions for novel research.