果蝇学习记忆行为的分子机制

分子遗传学技术的应用一方面发展了新的神经组织学方法,使果蝇脑中的细微结构得以展示;另一方面,对记忆从形成到提取过程中信息处理的研究,表明蘑菇体可能在形成长时程记忆方面起重要作用,而一对背内侧核团（dorsal paired medial cells）与蘑菇体之间的信息传递对于记忆的“提取(retrieval)”是至关重要的.行为功能检测为视觉信号整和的研究提供了新的实验依据,从而使果蝇蘑菇体的高级脑中枢功能逐渐被揭示出来.     

Molecular and Structural Characterization of Barley Vernalization Genes

Vernalization, the requirement of a period of low temperature to induce transition from the vegetative to reproductive state, is an evolutionarily and economically important trait in the Triticeae. The genetic basis of vernalization in cultivated barley (Hordeum vulgare subsp. vulgare) can be defined using the two-locus VRN-H1/VRN-H2 model. We analyzed the allelic characteristics of HvBM5A, the candidate gene for VRN-H1, from ten cultivated barley accessions and one wild progenitor accession (subsp. spontaneum), representing the three barley growth habits – winter, facultative, and spring. We present multiple lines of evidence, including sequence, linkage map location, and expression, that support HvBM5A being VRN-H1. While the predicted polypeptides from different growth habits are identical, spring accessions contain a deletion in the first intron of HvBM5A that may be important for regulation. While spring HvBM5A alleles are typified by the intron-localized deletion, in some cases, the promoter may also determine the allele type. The presence/absence of the tightly linked ZCCT-H gene family members on chromosome 4H perfectly correlates with growth habit and we conclude that one of the three ZCCT-H genes is VRN-H2. The VRN-H2 locus is present in winter genotypes and deleted from the facultative and spring genotypes analyzed in this study, suggesting the facultative growth habit (cold tolerant, vernalization unresponsive) is a result of deletion of the VRN-H2 locus and presence of a winter HvBM5A allele. All reported barley vernalization QTLs can be explained by the two-locus VRN-H1/VRN-H2 model based on the presence/absence of VRN-H2 and a winter vs. spring HvBM5A allele. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users.     

Molecular Evolution of hisB Genes

The sixth and eighth steps of histidine biosynthesis are catalyzed by an imidazole glycerol-phosphate (IGP) dehydratase (EC 4.2.1.19) and by a histidinol-phosphate (HOL-P) phosphatase (EC 3.1.3.15), respectively. In the enterobacteria, in Campylobacter jejuni and in Xylella/Xanthomonas the two activities are associated with a single bifunctional polypeptide encoded by hisB. On the other hand, in Archaea, Eucarya, and most Bacteria the two activities are encoded by two separate genes. In this work we report a comparative analysis of the amino acid sequence of all the available HisB proteins, which allowed us to depict a likely evolutionary pathway leading to the present-day bifunctional hisB gene. According to the model that we propose, the bifunctional hisB gene is the result of a fusion event between two independent cistrons joined by domain-shuffling. The fusion event occurred recently in evolution, very likely in the proteobacterial lineage after the separation of the - and the -subdivisions. Data obtained in this work established that a paralogous duplication event of an ancestral DDDD phosphatase encoding gene originated both the HOL-P phosphatase moiety of the E. coli hisB gene and the gmhB gene coding for a DDDD phosphatase, which is involved in the biosynthesis of a precursor of the inner core of the outer membrane lipopolysaccharides (LPS).     

Molecular Characterization of Puroindolines and their Encoding Genes in Aegilops Ventricosa

Puroindolines, the tryptophan-rich proteins controlling grain hardness in wheat, appeared as two pairs of 13 kDa polypeptides in the Acid-PAGE (A-PAGE) and two-dimensional A-PAGE×SDS-PAGE patterns of starch-granule proteins from wild allotetraploid wheat Aegilops ventricosa Tausch. (2n = 4x = 28, genomes D^vD^vN^vN^v). Puroindoline pair a1 + a2 reacted strongly with an antiserum specific for puroindoline-a from common wheat (Triticum aestivum L.), whereas puroindoline pair b1 + b2 exhibited A-PAGE relative mobilities similar to that of puroindoline-b in Aegilops tauschii (Coss.), the D-genome donor to both common wheat and Ae. ventricosa. Puroindolines a2 and b1 were found to be encoded by alleles Pina-D1a and Pinb-D1h on chromosome 5D^v, respectively, whereas puroindolines a1 and b2 were assumed to be under the genetic control of chromosome 5N^v. Puroindoline a1 encoded by the novel Pina-N1a allele exhibited a high level of amino acid variation with respect to puroindoline-a. On the other hand, the tryptophan-rich region of puroindoline b2 encoded by allele Pinb-N1a showed a sequence change from lysine-42 to arginine, with no effect on the amount of protein b2 accumulated on the starch granules. A partial duplication of the pin-B gene (Pinb-relic) was identified about 1100 bp downstream from Pinb-D1 on chromosome 5D^v. The present findings are the first evidence of a tetraploid wheat species in which four puroindoline genes are expressed. The potential of Ae. ventricosa as a source of genes that may be used to modulate endosperm texture and other valuable traits in cultivated wheat species is discussed.     

羊肚菌分子鉴定及功能基因研究进展

羊肚菌作为珍贵的食药用真菌,具有很高的经济价值.就近年来羊肚菌分子生物学研究的进展从分子鉴定、系统学研究、功能基因等方面进行了分析总结.结果显示,目前利用分子标记已实现羊肚菌属快捷的分子鉴定,较全面揭示了属内种群的遗传多样性和亲缘关系;利用组学技术初步探索了羊肚菌菌核形成及子实体发育机制;此外还克隆表达了与羊肚菌抗逆响...     

Biology of Lilioceris spp. (Coleoptera: Chrysomelidae) and their parasitoids in Europe

The biology and parasitoid complex of the lily leaf beetle (LLB), Lilioceris lilii Scopoli, and two congeneric species were investigated in Europe, as part of a biological control program against the LLB in North America. Eggs, larvae, and adults of L. lilii were collected in several countries in Europe, on both cultivated and wild Lilium spp., and reared in the laboratory and under natural conditions. Parasitoids were obtained and their biologies were studied. Similar investigations were made in Switzerland on two closely related species Lilioceris tibialis (Villa) found on wild Lilium spp., and Lilioceris merdigera (L.) on several other Liliaceae. The three species are strictly univoltine. Adults overwinter and lay eggs on leaves in early spring. The three beetle species have four instars, which were characterized by their head capsule width. Pupation occurs in a cocoon in the soil. Adults emerge in late summer and start feeding before reaching overwintering sites. Egg and larval parasitoids were obtained. Eggs of L. lilii and L. merdigera were parasitized by the mymarid Anaphes sp., a multivoltine species that needs alternate hosts for overwintering. Larvae were heavily attacked by several parasitoids, among which the most abundant were three ichneumonids, Lemophagus pulcher (Szepligeti), L. errabundus (Gravenhorst), and Diaparsis jucunda (Holmgren), and the eulophid Tetrastichus setifer Thomson. All four parasitoid species were found in the three beetles and in most European regions, but strong variations were observed in their relative abundance among hosts and geographic regions. Three of the four main larval parasitoids are strictly univoltine, whereas L. pulcher has a partial second generation. Lemophagus spp. are frequently parasitized by the ichneumonid hyperparasitoid Mesochorus lilioceriphilus Schwenke. Further details of the biology of the parasitoids are described, and their potential as biological control agents is discussed.     

Molecular phylogeny of Phebalium (Rutaceae: Boronieae) and related genera based on the nrDNA regions ITS 1+2

Parsimony analyses of the internal transcribed spacer regions of nuclear ribosomal DNA (ITS 1 & ITS 2) for 38 taxa sampled from the Phebalium group (Rutaceae: Boronieae) and two outgroups confirm that, with the exception of Phebalium sensu stricto and Rhadinothamnus, six of the currently recognised genera within the group are monophyletic. The data indicate that Phebaliums. str. is paraphyletic with respect to Microcybe, and Rhadinothamnus is paraphyletic with respect to Chorilaena. Rhadinothamnus and Chorilaena together are the sister group to Nematolepis. Drummondita, included as an outgroup taxon, clustered within the ingroup as sister to Muiriantha and related to Asterolasia.The phylogeny suggests that the evolution of major clades within a number of these genera (e.g. Phebalium) relates to vicariance events between eastern and south-western Australia. Leionema is an eastern genus, with the most basal taxon being the morphologically distinct Leionema ellipticum from northern Queensland. Leionema also includes one species from New Zealand, but this species (as with some others) proved difficult to sequence and its phylogenetic position remains unknown. Taxonomic changes at the generic level are recommended.The authors wish to thank Paul G.Wilson, PERTH, for advice and discussion, and Paul Forster, BRI, for collecting and providing material of Leionema ellipticum. The project was supported by a Melbourne University Postgraduate Award (to BM), the Australian Biological Resources Study (ABRS), Australian Systematic Botany Society and Wolf Den (Australia) Investments.     

The Mitochondrial Genome of Xiphinema americanum sensu stricto (Nematoda: Enoplea): Considerable Economization in the Length and Structural Features of Encoded Genes

The complete sequence of the mitochondrial genome of the plant parasitic nematode Xiphinema americanum sensu stricto has been determined. At 12626bp it is the smallest metazoan mitochondrial genome reported to date. Genes are transcribed from both strands. Genes coding for 12 proteins, 2 rRNAs and 17 putative tRNAs (with the tRNA-C, I, N, S1, S2 missing) are predicted from the sequence. The arrangement of genes within the X. americanum mitochondrial genome is unique and includes gene overlaps. Comparisons with the mtDNA of other nematodes show that the small size of the X. americanum mtDNA is due to a combination of factors. The two mitochondrial rRNA genes are considerably smaller than those of other nematodes, with most of the protein encoding and tRNA genes also slightly smaller. In addition, five tRNAs genes are absent, lengthy noncoding regions are not present in the mtDNA, and several gene overlaps are present. [Reviewing Editor: Dr. Yues van de Peer] F. Lamberti: Deceased, 2004     

Molecular identification and differentiation of Brevibacterium species and strains

Amplified ribosomal DNA restriction enzyme analysis (ARDRA), pulsed field gel electrophoresis (PFGE) and ribotyping were used to differentiate among 24 strains of Brevibacterium linens, Brevibacterium casei and Brevibacterium epidermidis obtained from type culture collections or isolated from various smear ripened cheeses. ARDRA was applied to the 16S rDNA. B. linens was shown to be a quite heterogenic group with 2 to at least 4 copies of rrn operons per strain with aberrant nucleotide sequences. AccI gave genus specific restriction patterns and was used to separate Brevibacterium from Corynebacterium species. The expected species specificity of TaqI applied to B. linens type culture strains, but not to all strains isolated from cheese. By AvaI restriction, B. casei and B. linens were differentiated from B. epidermidis and the orange pigmented Arthrobacter casei, a new species of coryneform bacteria; by XmnI restriction, B. linens and B. epidermidis were differentiated from B. casei. One of 4 B. linens genotypes could not be distinguished from B. casei by this method. Here, the typical orange B. linens pigments were used for classification, which was confirmed by partial sequencing of the 16S rDNA.     

Diversification and Independent Evolution of Troponin C Genes in Insects

Troponin C (TpnC), the calcium-binding subunit of the troponin regulatory complex in the muscle thin filament, is encoded by multiple genes in insects. To understand how TpnC genes have evolved, we characterized the gene number and structure in a number of insect species. The TpnC gene complement is five genes in Drosophilidae as previously reported for D. melanogaster. Gene structures are almost identical in D. pseudoobscura, D. suboboscura, and D. virilis. Developmental patterns of expression are also conserved in Drosophila subobscura and D. virilis. Similar, but not completely equivalent, TpnC gene repertoires have been identified in the Anopheles gambiae and Apis mellifera genomes. Insect TpnC sequences can be divided into three groups, allowing a systematic classification of newly identified genes. The pattern of expression of the Apis mellifera genes essentially agrees with the pattern in Drosophilidae, providing further functional support to the classification. A model for the evolution of the TpnC genes is proposed including the most likely pathway of insect TpnC diversification. Our results suggest that the rapid increase in number and sequence specialization of the adult Type III isoforms can be correlated with the evolution of the holometabolous mode of development and the acquisition of asynchronous indirect flight muscle function in insects. This evolutionarily specialization has probably been achieved independently in different insect orders.Reviewing Editor: Dr. Rüdiger Cerff     

蝴蝶兰花发育的分子生物学研究进展

蝴蝶兰花非常独特且高度进化,如萼片瓣化、瓣片特化为唇瓣、雌雄蕊合生成合蕊柱及子房发育须由授粉启动等,是单子叶植物花发育研究的理想材料。近年来蝴蝶兰花发育分子生物学取得了重要进展。该文就近年来国内外有关蝴蝶兰开花转换及花器官发育相关基因研究以及B类基因与兰花花被的进化发育关系方面的研究进展进行综述。研究表明:MADS基因在蝴蝶兰开花转换及花器官发育过程中起重要作用,推测其中的DEF(DE-FICIENS)-like基因早期经过2轮复制,形成了4类不同的DEF-like基因,进而决定兰花花被属性。蝴蝶兰花发育分子生物学的深入研究,将极大地利于通过基因工程手段提高蝴蝶兰花品质如花色改良及花期调控等,推动分子育种进程。     

基于分子与形态证据的桃色无心菜(石竹科)分类地位探讨

广义无心菜属(Arenaria L.s.l.)是石竹科(Caryophyllaceae)中分类较为困难的大属之一,基于分子系统学研究结果该属目前已被拆分为多属.基于形态学证据,桃色无心菜(Arenaria melandryoides Edgew.)被置于无心菜属齿瓣亚属[subg.Odontostemma(G.Don)...     

Ionic mechanism of a voltage-dependent current elicited by cyclic AMP

Intracellular pressure injection of cyclic AMP induces a slow voltage-dependent inward current in some neurons of Aplysia californica.The time course, voltage dependence, and ionic sensitivities of this response are nearly identical to those of the voltage-dependent calcium current induced by serotonin in the same preparation. The response to cyclic AMP is unaffected by changes in the extracellular concentration of chloride or potassium. The current is slowly but minimally reduced by a sodium-free solution. The calcium channel blocker, cadmium, blocks the current elicited by injection of cyclic AMP. The data presented here suggest that cyclic AMP can induce a voltage-dependent calcium current.     

Development of Molecular Cytogenetics and Physical Mapping of Ribosomal RNA Genes in Lupinus

Identification of individual chromosomes in Lupinus is not possible due to gradient in size and similar morphology. To overcome this problem, molecular cytogenetics was developed for Lupinus. As an initial step in karyotype analysis, fluorescent in situ hybridization (FISH) was performed to determine genomic distribution of rRNA genes in L. hispanicus, L. luteus and L. × hispanicoluteus. It was found that all three diploid species posses two chromosome pairs carrying 18S-5.8S-25S rDNA and one chromosome pair carrying 5S rDNA. The use of probes for rDNA permitted unambiguous identification of three different pairs of chromosomes and revealed conservation of the number of rDNA loci among the three species. The study represents the first step in physical mapping of Lupinus genome through FISH by providing distinct chromosome landmarks. This revised version was published online in July 2006 with corrections to the Cover Date.     

Molecular Organization of 5S rDNAs in Rajidae (Chondrichthyes): Structural Features and Evolution of Piscine 5S rRNA Genes and Nontranscribed Intergenic Spacers

The genomic and gene organisation of 5S rDNA clusters have been extensively characterized in bony fish and eukaryotes, providing general issues for understanding the molecular evolution of this multigene DNA family. By contrast, the 5S rDNA features have been rarely investigated in cartilaginous fish (only three species). Here, we provide evidence for a dual 5S rDNA gene system in the Rajidae by sequence analysis of the coding region (5S) and adjacent nontranscribed spacer (NTS) in five Mediterranean species of rays (Rajidae), and in a large number of piscine taxa including lampreys and bony fish. As documented in several bony fish, two functional 5S rDNA types were found here also in the rajid genome: a short one (I) and a long one (II), distinguished by distinct 5S and NTS sequences. That the ancestral piscine genome had these two 5S rDNA loci might be argued from the occurrence of homologous dual gene systems that exist in several fish taxa and from 5S phylogenetic relationships. An extensive analysis of NTS-II sequences of Rajidae and Dasyatidae revealed the occurrence of large simple sequence repeat (SSR) regions that are formed by microsatellite arrays. The localization and organization of SSR within the NTS-II are conserved in Rajiformes since the Upper Cretaceous. The direct correlation between the SSRs extension and the NTS length indicated that they might play a role in the maintenance of the larger 5S rDNA clusters in rays. The phylogenetic analysis indicated that NTS-II is a valuable systematic tool limited to distantly related taxa of Rajiformes. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users. [Reviewing Editor: Dr. Rafael Zardoya]     

Identification of Genes That Promote or Inhibit Olfactory Memory Formation in Drosophila

Genetic screens in Drosophila melanogaster and other organisms have been pursued to filter the genome for genetic functions important for memory formation. Such screens have employed primarily chemical or transposon-mediated mutagenesis and have identified numerous mutants including classical memory mutants, dunce and rutabaga. Here, we report the results of a large screen using panneuronal RNAi expression to identify additional genes critical for memory formation. We identified >500 genes that compromise memory when inhibited (low hits), either by disrupting the development and normal function of the adult animal or by participating in the neurophysiological mechanisms underlying memory formation. We also identified >40 genes that enhance memory when inhibited (high hits). The dunce gene was identified as one of the low hits and further experiments were performed to map the effects of the dunce RNAi to the α/β and γ mushroom body neurons. Additional behavioral experiments suggest that dunce knockdown in the mushroom body neurons impairs memory without significantly affecting acquisition. We also characterized one high hit, sickie, to show that RNAi knockdown of this gene enhances memory through effects in dopaminergic neurons without apparent effects on acquisition. These studies further our understanding of two genes involved in memory formation, provide a valuable list of genes that impair memory that may be important for understanding the neurophysiology of memory or neurodevelopmental disorders, and offer a new resource of memory suppressor genes that will aid in understanding restraint mechanisms employed by the brain to optimize resources.