Generation and analysis of ESTs from the grass carp, Ctenopharyngodon idellus

Grass carp, Ctenopharyngodon idellus (Valenciennes, 1844), is an economically important species widely cultured in the world, but its genome research resources are largely lacking. The objectives of this study were to construct normalized cDNA libraries for efficient EST analysis, to generate ESTs from these libraries, and to identify EST-related molecular markers such as microsatellites and single nucleotide polymorphisms (SNPs) for genetic analysis of this species. A total of 6,269 ESTs were generated representing 4,815 unique sequences, from which 105 putative microsatellites and 5,228 SNPs were identified. These genome resources provide the material basis for future genetic and functional analyses in this species.     

Shotgun proteomic analysis of mulberry dwarf phytoplasma

Background  

Mulberry dwarf (MD), which is caused by phytoplasma, is one of the most serious infectious diseases of mulberry. Phytoplasmas have been associated with diseases in several hundred plant species. The inability to culture phytoplasmas in vitro has hindered their characterization at the molecular level. Though the complete genomes of two phytoplasmas have been published, little information has been obtained about the proteome of phytoplasma. Therefore, the proteomic information of phytoplasmas would be useful to elucidate the functional mechanisms of phytoplasma in many biological processes.     

Genome-wide identification and characterization of putative cytochrome P450 genes in the model legume <Emphasis Type="Italic">Medicago truncatula</Emphasis>

In plants, cytochrome P450 is a group of monooxygenases existing as a gene superfamily and plays important roles in metabolizing physiologically important compounds. However, to date only a limited number of P450s have been identified and characterized in legumes. In this study, data mining methods were used, and 151 putative P450 genes in the model legume Medicago truncatula were identified, including 135 novel sequences. These genes were classified into 9 clans and 44 families by sequence similarity, and among those 4 new clans and 21 new families not reported previously in legumes. By comparison of these genes with P450 genes in Arabidopsis and rice, it was found that most of the known P450 families in dicot species exist in M. truncatula. The representative protein sequences of putative P450s were aligned, and the secondary elements were assigned based on the known structure P450BM3. Putative substrate recognition sites (SRSs) and substrate binding sites were also identified in these sequences. In addition, the ESTs-derived expression profiles (digital Northern) of the putative P450 genes were analyzed, which was confirmed by semi-quantitative RT-PCR analyses of several selected P450 genes. These results will provide a base for catalogue information on P450 genes in M. truncatula and for further functional analysis of P450 superfamily genes in legumes.     

Citron kinase controls abscission through RhoA and anillin

The small GTPase RhoA plays a crucial role in the different stages of cytokinesis, including contractile ring formation, cleavage furrow ingression, and midbody abscission. Citron kinase (CIT-K), a protein required for cytokinesis and conserved from insects to mammals, is currently considered a cytokinesis-specific effector of active RhoA. In agreement with previous observations, we show here that, as in Drosophila cells, CIT-K is specifically required for abscission in mammalian cells. However, in contrast with the current view, we provide evidence that CIT-K is an upstream regulator rather than a downstream effector of RhoA during late cytokinesis. In addition, we show that CIT-K is capable of physically and functionally interacting with the actin-binding protein anillin. Active RhoA and anillin are displaced from the midbody in CIT-K-depleted cells, while only anillin, but not CIT-K, is affected if RhoA is inactivated in late cytokinesis. The overexpression of CIT-K and of anillin leads to abscission delay. However, the delay produced by CIT-K overexpression can be reversed by RhoA inactivation, while the delay produced by anillin overexpression is RhoA-independent. Altogether, these results indicate that CIT-K is a crucial abscission regulator that may promote midbody stability through active RhoA and anillin.     

SSR与SRAP标记在玉米品种鉴定中的比较研究

利用SSR标记和SRAP标记对19个玉米品种及8份莱农15样品进行了分析,比较了2种标记的分辨能力及在亲缘关系和杂交种纯度鉴定中的表现.与SSR标记相比,SRAP标记用于玉米品种鉴定扩增住点数量更多,PIC值更高,具有更高的分辨率;在亲缘关系分析方面,SSR检测的遗传距离变幅更大,2种标记计算的遗传距离呈极显著正相关,分类结果基本一致;在杂交种纯度检测中,SRAP标记的期望位点在杂交种群体中检测率高于SSR标记相应位点,检测杂交种纯度结果更接近田问种植鉴定,因而准确度更高.SRAP在玉米品种鉴定中具有一定的优势,可作为SSR标记技术的有益补充,特别是在杂交种纯度鉴定中应用.     

DNA放射损伤与p53

电离辐射等多种因素可以引起DNA损伤,表现为碱基改变、DNA双链断裂(DNA double-strand breaks,DSBs)和DNA单链断裂(Single-strand breaks,SSBs)等多种形式。DNA损伤后,细胞发生应答,即引起细胞周期阻滞和/或细胞程序性死亡,以减少损伤引起的染色体畸变和基因组不稳定。在细胞应答过程中,p53蛋白水平和活性均发生变化,介导细胞周期阻滞、程序性死亡,并直接参与DNA损伤修复过程。     

Identification of Self-Incompatibility Genotypes of Apricot (<Emphasis Type="Italic">Prunus armeniaca</Emphasis> L.) by S-Allele-Specific PCR Analysis

A cDNA of 417 bp encoding an S-RNase gene, named PA S3, was isolated from apricot, Prunus aremeniaca. Nine S-alleles, S₁–S₉, were recognized by S-allele-specific PCR and confirmed by Southern blot analysis using PA S3 as probe. The S-genotypes of the six cultivars were determined and the results of self- and cross-pollination tests among the six cultivars were consistent with the predicted S-haplotypes by PCR analysis.     

Isolation and characterization of a Pti1 homologue from soybean

A full-length gene GmPti1 was identified from soybean in an EST sequencing project by its homology to tomato Pti1. It encoded a protein of 366 amino acids. RT-PCR analysis showed that the GmPti1 expression was induced by salicylic acid and wounding. The deduced amino acid sequence had a Ser/Thr/Tyr kinase domain. GmPti1 protein was expressed in E. coli as an MBP fusion, purified by amylose resin and examined for its autophosphorylation ability. The phosphorylation assay in vitro showed that GmPti1 had kinase activity in the presence of Mn2+. These results demonstrated that GmPti1 represented a new Pti1-like gene, unlike the two published genes sPti1a and sPti1b, which encoding proteins had no autophosphorylation ability.     

Septin 3 (G-septin) is a developmentally regulated phosphoprotein enriched in presynaptic nerve terminals

The septins are GTPase enzymes with multiple roles in cytokinesis, cell polarity or exocytosis. The proteins from the mammalian septin genes are called Sept1-10. Most are expressed in multiple tissues, but the mRNA for Sept5 (CDCrel-1) and Sept3 (G-septin) appear to be primarily expressed in brain. Sept3 is phosphorylated by cGMP-dependent protein kinase I (PKG-I) and the cGMP/PKG pathway is involved in presynaptic plasticity. Therefore to determine whether Sept3 specifically associates with neurones and nerve terminals we investigated its distribution in rat brain and neuronal cultures. Sept3 protein was detected only in brain by immunoblot, but not in 12 other tissues examined. Levels were high in all adult brain regions, and reduced in those enriched in white matter. Expression was developmentally regulated, being absent in the early embryo, low in late embryonic rat brain and increasing after birth. Like dynamin I, Sept3 was specifically enriched in synaptosomes compared with whole brain, and was only found in a peripheral membrane extract and not in the soluble or membrane extracts. Sept3 was particularly abundant in mossy fibre nerve terminals in the hippocampus. In primary cultured hippocampal neurones Sept3 immunoreactivity was punctate in neurites and predominantly localized to presynaptic terminals, strongly colocalizing with synaptophysin and dynamin I. The specific nerve terminal localization was confirmed by immunogold electron microscopy. Together this shows that Sept3 is a neurone-specific protein highly enriched in nerve terminals which supports a secretory role in synaptic vesicle recycling.     

Segregation Analysis on Genetic System of Quantitative Traits in Plants

Based on the traditional polygene inheritance model of quantitative traits,the author suggests the major gene and polygene mixed inheritance model.The model was considered as a general one,while the pure major gene and pure polygene inheritance model was a specific case of the general model.Based on the proposed theory,the author established the segregation analysis procedure to study the genetic system of quantitative traits of plants.At present,this procedure can be used to evaluate the genetic effect of individual major genes (up to two to three major genes),the collective genetic effect of polygene,and their heritability value.This paper introduces how to establish the procedure,its main achievements,and its applications.An example is given to illustrate the steps,methods,and effectiveness of the procedure.