Proteomic characterization of messenger ribonucleoprotein complexes bound to nontranslated or translated poly(A) mRNAs in the rat cerebral cortex

Receptor-triggered control of local postsynaptic protein synthesis plays a crucial role for enabling long lasting changes in synaptic functions, but signaling pathways that link receptor stimulation with translational control remain poorly known. Among the putative regulatory factors are mRNA-binding proteins (messenger ribonucleoprotein, mRNP), which control the fate of cytosolic localized mRNAs. Based on the assumption that a subset of mRNA is maintained in an inactive state, mRNP-mRNA complexes were separated into polysome-bound (translated) and polysome-free (nontranslated) fractions by sucrose density centrifugation. Poly(A) mRNA-mRNP complexes were purified from a postmitochondrial extract of rat cerebral cortex by oligo(dT)-cellulose affinity chromatography. The mRNA processing proteins were characterized, from solution, by a nanoflow reverse phase-high pressure liquid chromatography-mu-electrospray ionization mass spectrometry. The majority of detected mRNA-binding proteins was found in both fractions. However, a small number of proteins appeared to be fraction-specific. This subset of proteins is by far the most interesting because the proteins are potentially involved in controlling an activity-dependent onset of translation. They include transducer proteins, kinases, and anchor proteins. This study of the mRNP proteome is the first step in allowing future experimentation to characterize individual proteins responsible for mRNA processing and translation in dendrites.     

人微小病毒3个主要蛋白基因真核表达载体的构建

目的:分别克隆人细小病毒B19三个主要蛋白VP1、VP2、NS1全长基因,构建真核表达载体。方法:利用PCR和分子克隆技术,分别将B19病毒vp1、vp2、ns1基因全长片段扩增后,构建带荧光标签的真核表达载体;在人体细胞中表达并通过荧光、RT-PCR和Western Blot、测序等方法鉴定。结果:成功构建了包含B19病毒vp1、vp2、ns1全长基因,并在人体细胞中表达了VP1、VP2、NS1蛋白。结论:人微小病毒B19三个主要蛋白基因得到克隆和表达,为进行相关的研究奠定了基础。     

Chloroplast PNPase exists as a homo-multimer enzyme complex that is distinct from the Escherichia coli degradosome.

In Escherichia coli, the exoribonuclease polynucleotide phosphorylase (PNPase), the endoribonuclease RNase E, a DEAD-RNA helicase and the glycolytic enzyme enolase are associated with a high molecular weight complex, the degradosome. This complex has an important role in processing and degradation of RNA. Chloroplasts contain an exoribonuclease homologous to E. coli PNPase. Size exclusion chromatography revealed that chloroplast PNPase elutes as a 580-600 kDa complex, suggesting that it can form an enzyme complex similar to the E. coli degradosome. Biochemical and mass-spectrometric analysis showed, however, that PNPase is the only protein associated with the 580-600 kDa complex. Similarly, a purified recombinant chloroplast PNPase also eluted as a 580-600 kDa complex after gel filtration chromatography. These results suggest that chloroplast PNPase exists as a homo-multimer complex. No other chloroplast proteins were found to associate with chloroplast PNPase during affinity chromatography. Database analysis of proteins homologous to E. coli RNase E revealed that chloroplast and cyanobacterial proteins lack the C-terminal domain of the E. coli protein that is involved in assembly of the degradosome. Together, our results suggest that PNPase does not form a degradosome-like complex in the chloroplast. Thus, RNA processing and degradation in this organelle differ in several respects from those in E. coli.     

SUMMARY OF GREEN PLANT PHYLOGENY AND CLASSIFICATION

Abstract— A cladogram of green plants involving all major extant groups of green algae, bryophytes, pteridophytes, and seed plants is presented. It is partly based on contributions by B. Mishler and S. Churchill, H. Wagner, and P. Crane. The relationships of green plants to other green organisms ( Prochloron , euglenophytes) are discussed. The characters and subclades of the cladogram are briefly discussed, with an attempt to indicate weak points. The possibility of including some major extinct groups is considered. A cladistic classification consistent with the cladogram is presented. Grades are abandoned as taxa and major clades like the division Chlorophyta (green algae excluding micro-monadophytes and charophytes sensu Mattox and Stewart), the division Streptophyta (charophytes + embryophytes), the subdivision Embryophytina (land plants or embryophytes), the superclass Tracheidatae (tracheophytes), and the class Spermatopsida (seed plants) are recognized.     

Fish community changes after minimum flow increase: testing quantitative predictions in the Rhône River at Pierre-Bénite, France

1. Many aspects of the flow regime influence the structure of stream communities, among which the minimum discharge left in rivers has received particular attention. However, instream habitat models predicting the ecological impacts of discharge management often lack biological validation and spatial generality, particularly for large rivers with many fish species. 2. The minimum flow at Pierre‐Bénite, a reach of the Rhône river bypassed by artificial channels, was increased from 10 to 100 m³ s^?1 in August 2000 (natural mean discharge 1030 m³ s^?1), resulting in a fivefold increase in average velocity at minimum flow. Fish were electrofished in several habitat units on 12 surveys between 1995 and 2004. 3. Principal components analysis revealed a significant change in the relative abundance of fish species. The relative abundance of species preferring fast‐flowing and/or deep microhabitats increased from two‐ to fourfold after minimum flow increase. A change in community structure confirmed independent quantitative predictions of an instream habitat model. This change was significantly linked to minimum flow increase, but not to any other environmental variables describing high flows or temperature at key periods of fish life cycle. The rapidity of the fish response compared with the lifespan of individual species can be explained by a differential response of specific size classes. 4. The fish community at Pierre‐Bénite is in a transitional stage and only continued monitoring will indicate if the observed shift in community structure is perennial. We expect that our case study will be compared with other predictive tests of the impacts of flow restoration in large rivers, in the Rhône catchment and elsewhere.     

利用AFLP遗传连锁图定位大麦苗期对叶锈病的部分抗性基因

借助大麦染色体ＡＦＬＰ标记遗传连锁图和ＭａｐＱＴＬＶ３．０作图软件,对大麦叶病的数量抗性基因进行了定位分析,明确了大麦部分抗性品种Ｖａｄａ对叶锈病的潜育期由分别位于染色体１、２、６、７上离短臂末端７９ｃＭ、１８６ｃＭ、５８ｃＭ和１１７ｃＭ处的４个数量抗性基因所控制。