植物丝氨酸/精氨酸丰富(SR)蛋白的结构和功能及其在植物发育中的作用

丝氨酸／精氨酸丰富（SR）蛋白家族是真核生物中的一类剪接因子,在前体mRNA的组成性和选择性剪接中起作用。本文就近十几年来SR蛋白结构和功能及其在植物发育中的作用的研究进展作以介绍。     

Increased heart rate variability in mice overexpressing the Cu/Zn superoxide dismutase

Cu/Zn superoxide dismutase (SOD1) is implicated in various pathological conditions including Down's syndrome, neurodegenerative diseases, and afflictions of the autonomic nervous system (ANS). To assess the SOD1 contribution to ANS dysfunction, especially its influence on cardiac regulation, we studied the heart rate variability (HRV) and cardiac arrhythmias in conscious 12-month-old male and female transgenic mice for the human SOD1 gene (TghSOD1). TghSOD1 mice presented heart rate reduction as compared with control FVB/N individuals. All HRV parameters reflecting parasympathetic activity were increased in TghSOD1. Pharmacological studies confirmed that the parasympathetic tone was exacerbated and the sympathetic pathway was functional in TghSOD1 mice. A high frequency of atrioventricular block and premature ventricular contractions was observed in TghSOD1. By biochemical assays we found that SOD1 activities were multiplied by 9 and 4 respectively in the heart and brainstem of transgenic mice. A twofold decrease in cholinesterase activity was observed in the heart but not in the brainstem. We demonstrate that SOD1 overexpression induces an ANS dysfunction by an exacerbated vagal tone that may be related to impaired cardiac activity of the cholinesterases and may explain the high occurrence of arrhythmias.     

Statistical Assessment of Variability of Terminal Restriction Fragment Length Polymorphism Analysis Applied to Complex Microbial Communities

The variability of terminal restriction fragment polymorphism analysis applied to complex microbial communities was assessed statistically. Recent technological improvements were implemented in the successive steps of the procedure, resulting in a standardized procedure which provided a high level of reproducibility.Terminal restriction fragment length polymorphism (T-RFLP) analysis is a robust, high-resolution, high-throughput, rapid, and cost-effective method for studying the structures of microbial communities (3, 10). T-RFLP analysis is based on group-specific variations in the restriction patterns of molecular markers essential to all life forms (i.e., rRNA genes) or unique to a particular physiological group (e.g., ammonia-oxidizing and sulfate-reducing bacteria) which generate specific and characteristic terminal restriction fragment (T-RF) patterns from mixed fluorescently labeled amplicon pools of environmental nucleic acid extracts. This analysis has developed recently into one of the favorite techniques for the rapid assessment of the structures of bacterial communities. Refinements of the technique and data analysis have been introduced (5, 8, 11, 14, 20-22). Improvements have been made to the sampling procedure (16), to the DNA extraction and amplification steps (17, 19, 26), and to enzymatic restriction digestion (2, 6). Statistical analysis has also been improved in the treatment of the raw data and the selection of logical binning and clustering algorithms resulting, for instance, in the alignment of replicate profiles into a single consensus profile (1, 13). Finally, recent developments have been proposed for the statistical analysis of the profiles using multivariate techniques from numerical ecology (4, 7, 9, 23-25, 27).Both the resolution and reproducibility of T-RFLP analysis have already been assessed using artificially created bacterial communities (12) comprising up to 30 different clones or bacterial species. However, to the best knowledge of the authors, so far no study has been conducted to assess statistically the dissimilarities obtained in the electropherogram profiles when more complex bacterial communities from natural samples have been analyzed. The main purpose of this report is then to assess statistically the resolution and reproducibility of a standardized T-RFLP protocol, as applied to the analysis of 16S rRNA gene pools from complex communities. The statistical analysis was carried out at successive steps of the procedure, from the initial PCR amplification to the sizing of the obtained T-RFs.The samples used for this study were taken from a sequencing batch bubble column reactor inoculated with activated sludge from a municipal wastewater treatment plant and operated in such a way as to produce aerobic granular sludge able to remove carbon, nitrogen, and phosphate from an artificial wastewater sample containing acetate, ammonium, and phosphate. Samples were taken at different steps of operation of the reactor systems. The standardized protocol used in the present report is presented in detail in the supplemental material. Note that the methodology implied in the extraction of the total bacterial DNA is not discussed in the context of this work. The T-RFLP protocol was conceived on the basis of recent developments made in the protocol at various stages of the T-RFLP analysis and was implemented with optimized procedures allowing us to minimize potential biases and to ensure a high degree of reproducibility. Whenever possible, technological advances in instrumentation were included, as for instance with the application of optimized electrophoresis conditions and the use of more complex sizing standards and brighter fluorochromes. The use of relatively large and precise amounts of digested PCR fragments (200 ng per replica) also contributed to a drastic reduction of the background noise, which was usually observed to be equal to only about 10 relative fluorescence units (RFU).Numerical treatment and analysis of the data were carried out with R (R Development Core Team) and the Vegan library (18). We used asymmetric dissimilarity indices to compare T-RFLP profiles using the Jaccard formula, so that the double absence of a T-RF was not considered a resemblance between two profiles (15). The Jaccard dissimilarity was applied to binary data, i.e., the presence/absence of T-RFs. Moreover, to take into account the relative intensity of T-RF areas within each profile in the comparison, we used Ruzicka dissimilarity, which is the Jaccard index applied to quantitative data. Both dissimilarity measures range from 0 (identical profiles) to 1 (different profiles with no T-RF in common). Numerical treatment of the data was also carried out on the modified results, so as to reduce potential biases induced by the inconsistent presence of T-RFs showing very small amounts of fluorescence. T-RF signals just above the detection threshold (low signal-to-noise ratio) can be a cause of suboptimal fingerprinting reproducibility. For this reason, small-area T-RFs (<300 RFU) were suppressed when they were not present in all replicate profiles of a sample.     

珍稀鹤类巢址的空间聚类识别方法

依据2003年到2005年松嫩平原西部地区珍稀鹤类巢址调查数据,利用三种不同类型的指数进行分析研究:(1)拓扑指数,Voronoi图面积;(2)统计指数,Morishita指数;(3)空间指数,分维数.结果表明珍稀鹤类巢址空间格局具有明显的空间聚类分布,这三个指数使我们对珍稀鹤类巢址的聚类现象有了定量的认识,加深对自然保护区资源保护的重要性.     

3D analysis from micro-MRI during in situ compression on cancellous bone

A mini-compression jig was built to perform in situ tests on bovine trabecular bone monitored by micro-MRI. The MRI antenna provided an isotropic resolution of 78 μm that allows for a volume correlation method to be used. Three-dimensional displacement fields are then evaluated within the bone sample during the compression test. The performances of the correlation method are evaluated and discussed to validate the technique on trabecular bone. By considering correlation residuals and estimates of acquisition noise, the measured results are shown to be trustworthy. By analyzing average strain levels for different interrogation volumes along the loading direction, it is shown that the sample size is less than that of a representative volume element. This study shows the feasibility of the 3D-displacement and strain field analyses from micro-MRI images. Other biological tissues could be considered in future work.     

Global transcriptional response of pig brain and lung to natural infection by Pseudorabies virus

Background  

Pseudorabies virus (PRV) is an alphaherpesviruses whose native host is pig. PRV infection mainly causes signs of central nervous system disorder in young pigs, and respiratory system diseases in the adult.     

Involvement of ABC transporters in melanogenesis and the development of multidrug resistance of melanoma

Because melanomas are intrinsically resistant to conventional radiotherapy and chemotherapy, many alternative treatment approaches have been developed such as biochemotherapy and immunotherapy. The most common cause of multidrug resistance (MDR) in human cancers is the expression and function of one or more A TP‐b inding c assette (ABC) transporters that efflux anticancer drugs from cells. Melanoma cells express a group of ABC transporters (such as ABCA9, ABCB1, ABCB5, ABCB8, ABCC1, ABCC2, and ABCD1) that may be associated with the resistance of melanoma cells to a broad range of anticancer drugs and/or of melanocytes to toxic melanin intermediates and metabolites. In this review, we propose a model (termed the ABC‐M model) in which the intrinsic MDR of melanoma cells is at least in part because of the transporter systems that may also play a critical role in reducing the cytotoxicity of the melanogenic pathway in melanocytes. The ABC‐M model suggests molecular strategies to reverse MDR function in the context of the melanogenic pathway, which could open therapeutic avenues towards the ultimate goal of circumventing clinical MDR in patients with melanoma.     

Spleen-dependent turnover of CD11b peripheral blood B lymphocytes in bovine leukemia virus-infected sheep

Lymphocyte homeostasis is determined by a critical balance between cell proliferation and death, an equilibrium which is deregulated in bovine leukemia virus (BLV)-infected sheep. We have previously shown that an excess of proliferation occurs in lymphoid tissues and that the peripheral blood population is prone to increased cell death. To further understand the mechanisms involved, we evaluated the physiological role of the spleen in this accelerated turnover. To this end, B lymphocytes were labeled in vivo using a fluorescent marker (carboxyfluorescein diacetate succinimidyl ester), and the cell kinetic parameters (proliferation and death rates) of animals before and after splenectomy were compared. We show that the enhanced cell death observed in BLV-infected sheep is abrogated after splenectomy, revealing a key role of the spleen in B-lymphocyte dynamics.