Identification of proteins overexpressed in papillary thyroid tumors

A modified method of proteome comparative analysis based on preliminary removal of cell structural proteins by extraction using salt buffer and subsequent separation of extracts by two-dimensional gel electrophoresis was developed. Identification of differentially expressed proteins by mass spectrometry has revealed three proteins with noticeably increased level of synthesis in most samples of papillary thyroid tumors compared to normal tissues. An increase in ubiquitin content was found for the first time. Oncomarker search efficiencies by two-dimensional gel electrophoresis and bioinformatic search were compared.     

Ultimate mechanisms of age-biased flea parasitism

Mechanisms that cause nonrandom patterns of parasite distribution among host individuals may influence the population and evolutionary dynamics of both parasites and hosts, but are still poorly understood. We studied whether survival, reproduction, and behavioral responses of fleas (Xenopsylla conformis) changed with the age of their rodent hosts (Meriones crassus), experimentally disentangling two possible mechanisms: (a) differential survival and/or fitness reward of parasites due to host age, and (b) active parasite choice of a host of a particular age. To explore the first mechanism, we raised fleas on rodents of two age groups and assessed flea survival as well as the quantity and quality of their offspring. To explore the second mechanism, three groups of fleas that differed in their previous feeding experience (no experience, experience on juvenile or experience on adult rodents) were given an opportunity to choose between juvenile and adult rodents in a Y-maze. Fleas raised on juvenile rodents had higher survival and had more offspring that emerged earlier than fleas raised on adults. However, fleas did not show any innate preference for juvenile rodents, nor were they able to learn to choose them. In contrast to our predictions, based on a single previous exposure, fleas learned to choose adult rodents. The results suggest that two mechanisms—differential survival and fitness reward of fleas, and associative learning by them—affect patterns of flea distribution between juvenile and adult rodents. The former increases whereas the latter reduces flea densities on juvenile rodents. The ability of fleas to learn to choose adult but not juvenile hosts may be due to: (a) a stronger stimulus from adults, (b) a higher profitability of adults in terms of predictability and abundance, or (c) the evolutionary importance of recognizing adult but not juvenile hosts as representatives of the species.     

Ultrastructure of ependyma in brain third ventricle of the rats exposed to repeated tail-suspension. Scanning electron microscopical study

By means of scanning electron microscopy the ultrastructure of ependyma was studied in the brain third ventricle of the rats repeatedly exposed to 14-day tail-suspension (TS). Animals were subjected to TS for 30 days, then readapted to horizontal position during 30 days and again, repeatedly subjected to TS for 14 days simultaneously with the rats which were in TS for the first time during 14 days. Repeated TS of rats, inspite of repeated redistribution of body liquid mediums in cranial direction, results in considerably less expressed destructive changes in ultrastructure of ependymocyte cilia, then after primary 14- and 30-day TS, showing much greater cerebrospinal fluid (CSF) outflow from brain ventricles into sagittal venous sinus at postponed for a long time, repeated simulation of weightlessness effects in comparison with CSF outflow at primery one.     

The comparative ecology and biogeography of parasites

Comparative ecology uses interspecific relationships among traits, while accounting for the phylogenetic non-independence of species, to uncover general evolutionary processes. Applied to biogeographic questions, it can be a powerful tool to explain the spatial distribution of organisms. Here, we review how comparative methods can elucidate biogeographic patterns and processes, using analyses of distributional data on parasites (fleas and helminths) as case studies. Methods exist to detect phylogenetic signals, i.e. the degree of phylogenetic dependence of a given character, and either to control for these signals in statistical analyses of interspecific data, or to measure their contribution to variance. Parasite–host interactions present a special case, as a given trait may be a parasite trait, a host trait or a property of the coevolved association rather than of one participant only. For some analyses, it is therefore necessary to correct simultaneously for both parasite phylogeny and host phylogeny, or to evaluate which has the greatest influence on trait expression. Using comparative approaches, we show that two fundamental properties of parasites, their niche breadth, i.e. host specificity, and the nature of their life cycle, can explain interspecific and latitudinal variation in the sizes of their geographical ranges, or rates of distance decay in the similarity of parasite communities. These findings illustrate the ways in which phylogenetically based comparative methods can contribute to biogeographic research.     

Host specificity in phylogenetic and geographic space

The measurement of host specificity goes well beyond counting how many host species can successfully be used by a parasite. In particular, specificity can be assessed with respect to how closely related the host species are, or whether a parasite exploits the same or different hosts across its entire geographic range. Recent developments in the measurement of biodiversity offer a new set of analytical tools that can be used to quantify the many aspects of host specificity. We describe here the multifaceted nature of host specificity, summarize the indices available to measure its different facets one at a time or in combination, and discuss their implications for parasite evolution and disease epidemiology.     

土壤中棉花黄萎病菌SYBR Green Ⅰ荧光RT-PCR定量检测技术研究

为实现田间土壤棉花黄萎病菌的早期检测,建立了土壤中棉花黄萎病菌的SYBR Green I荧光定量PCR检测方法。以含342bp PCR扩增产物的阳性质粒为参考,构建了标准曲线,并对该曲线的特异性、敏感性、可重复性进行了评价。结果表明,该方法具有快速、特异性强、敏感度高等特点。检测范围在3.8×103-3.8×108copies/μL之间有良好的线性关系,相关系数R2为0.996,扩增效率为101.5%,灵敏度比常规PCR方法高102倍。