Recent progress in the molecular biology of the clonedN-acetylglucosaminyltransferases

Several genes which code for theN-acetylglucosaminyltransferases have been cloned and characterized. Physiological and pathophysiological roles of the genes still remain to be elucidated but accumulated evidence suggests that theN-acetylglucosaminyltransferase genes are implicated in differentiation, morphogenesis and cancer metastasis.     

梨小食心虫化学感受蛋白cDNA的克隆、序列分析及原核表达

为了研究梨小食心虫Grapholita molesta化学感受蛋白（chemosensory proteins, CSPs）在化学感受系统中的作用, 本研究利用RT-PCR和RACE技术克隆到一条梨小食心虫化学感受蛋白的全长cDNA序列, 命名为GmolCSP （GenBank 登录号： JQ821389）。序列分析表明, GmolCSP开放阅读框序列为384 bp, 编码127个氨基酸残基, 预测N末端含有18个氨基酸组成的信号肽序列, 其成熟蛋白的预测分子量为12.80 kD, 等电点为8.33。该基因编码的氨基酸序列与其他鳞翅目昆虫化学感受蛋白的氨基酸序列具有较高同源性。RT-PCR结果显示, GmolCSP在梨小食心虫成虫触角、 去触角的头、 胸、 腹、 足和翅中都有表达。将GmolCSP重组到表达载体pET-32a中, 转入大肠杆菌Escherichia coli BL21（DE3）进行表达。SDS-PAGE和Western 印迹检测结果显示, 梨小食心虫化学感受蛋白基因在大肠杆菌中成功地表达出一个分子量约为29 kD的融合蛋白, 与预测的融合蛋白分子量大小一致。本研究结果为进一步研究该蛋白的分子结构和功能奠定了良好基础。     

Molecular phylogenetics of the tribeInuleae s. str.(Asteraceae), based on ITS sequences of nuclear ribosomal DNA

The sequences of the internal transcribed spacer (ITS) region of 18S–26S nrDNA for a sample of 16 taxa from theInuleae s. str. and two outgroup taxa are analysed cladistically with PAUP. A consensus tree of the four most parsimonious cladograms is presented. Three different tests of cladogram stability are conducted (Bremer support, parsimony jackknifing and bootstrapping); all tests indicate a high degree of support for the basal nodes of the tree. The ITS phylogeny of the tribe is compared with previous hypotheses based on morphological data. The position ofAnisopappus as sister group to the rest of the tribe is supported by the molecular data, but the proposed subdivision ofInuleae s. str. into a paleate grade group and an epaleate clade is not. The interpretation of the character evolution of, e.g. receptacular paleae and pappus features within the tribe is discussed.     

Intraspecific diversity of the Cassava Green Mite Mononychellus progresivus (Acari: Tetranychidae) using comparisons of mitochondrial and nuclear ribosomal DNA sequences and cross-breeding

Intraspecific diversity in Cassava Green Mite Mononychellus progresivus Doreste was examined using individuals collected in Benin and the Congo and in Columbia and Brazil. Comparisons were based on mitochondrial and ribosomal DNA sequences and the results of several cross-breeding experiments. Sequence variation was examined in a total of 1139 base pairs (bp) constituting the ITS2 ribosomal DNA (805 bp) and a fragment of the Cytochrome Oxidase I (COI) gene (334 bp). Sequence divergence is low, ranging from 0% to 2.1% for COI and from 0% to 0.4% for ITS2. Inter-strain comparisons have shown that the two African populations appear to be identical. They were similar to the Colombian population while the Brazilian population was clearly different. The data support the hypothesis of a single introduction of the species in the two African populations. Crossing experiments have shown partial hybrid sterility, suggesting a genetic incompatibility consistent with differences detected by sequence data. The results show the usefulness of molecular markers as a tool for determining taxonomic status and dispersion paths in spider mites.     

Short-term effects of wake- and bright light therapy on sleep in depressed youth

Chronotherapeutics are well established for the treatment of depression and associated sleeping problems in adults. However, effects are still understudied in adolescents. Two pilot studies highlighted the crucial role of sleep when it comes to the treatment of depression, by means of chronotherapeutics, in adolescents. The aim of the present study was to investigate the role of adjunctive wake therapy (WT) in addition to bright light therapy (BLT) with respect to sleep behaviors. In the present study, 62 depressed inpatients (aged 13–18 years; diagnosed with Beck Depression Inventory Revision) were randomly assigned to two groups: BLT only (BLT-group) and a combination of BLT and WT (COMB-group). After one night of WT adolescents in the COMB-group revealed longer sleep durations, time in bed, advanced sleep onset, less wakes during night and an improved sleep efficiency. However, one night of WT plus BLT had no additional effect on sleep parameters compared with BLT-group in the long run. Therefore, future studies should assess whether more nights of WT might lead to more sustainable effects.     

The determinants of stability in the human prion protein: insights into folding and misfolding from the analysis of the change in the stabilization energy distribution in different conditions

The dynamic evolution of the PrP(C) from its NMR-derived conformation to a beta-sheet-rich, aggregation-prone conformation is studied through all-atom, explicit solvent molecular dynamics in different temperature and pH conditions. The trajectories are analyzed by means of a recently introduced energy decomposition approach aimed at identifying the key residues for the stabilization and folding of the protein. It is shown that under native conditions the stabilization energy is concentrated in regions of the helices H1 and H3, whereas under misfolding conditions (low pH, high temperature, or mutations in selected sites) it is spread out over helix H2. Misfolding appears to be a rearrangement of the chain that disrupts most of the native secondary structure of the protein, producing some beta-rich conformations with an energy distribution similar to that of the native state.     

Molecular phylogeny of the entomopathogenic fungi of the genus Cordyceps (Ascomycota:Clavicipitaceae) and its evolutionary implications

Cordyceps is an endoparasite ascomycetous genus containing approximately 450 species with a diversity of insect hosts,traditionally included in the family Clavicipitaceae of Ascomycota.Establishing the relationships among species with a varied range of morphologies and hosts is of importance to our understanding of the phylogeny and co-evolution of parasites and hosts in entomopathogenic ascomycetes.To this end,we used a combination of molecular index and morphological characters from 40 representative species to carry out comprehensive molecular phylogenetic analyses.Based on the phylogenetic tree,we used the program DISCRETE for inferring the rates of evolution and finding ancestral states of morphological character.The phylogenetic analyses revealed two important points.(i) Types of perithecia attached to stroma reflected an evolutionary trend in Cordyceps.The vertically immersed perithecia form was the ancestral state,superficial and obliquely immersed perithecia were derived characters,obliquely immersed was irreversible.Species with obliquely immersed perithecia were in a closely related group and were the derived group.(ii) A strong correlation between fungal relatedness and the microhabitat supported the hypothesis that the host jumps through commingling in soil microhabitats.Based on the results of these analyses,host switching explains the diversity of entomopathogenic fungi of the genus Cordyceps.     

Assessment of genetic fidelity of micropropagated <Emphasis Type="Italic">Swertia chirayita</Emphasis> plantlets by ISSR marker assay

Inter simple sequence repeat (ISSR) marker assay was employed to validate the genetic fidelity of Swertia chirayita plantlets multiplied in vitro by axillary multiplication upto forty-two passages. Sixteen ISSR primers generated a total of 102 amplicons among the tissue-cultured plants. Forty-eight amplicons were amplified in the outlier (a Swertia species). The outlier (negative control) was employed to rule out the possibility that the invariant fingerprint was due to chance alone and that the ISSR technique employed was not discriminatory enough to detect the off-types. A homogenous amplification profile was observed for all the micropropagated plants. The results confirmed the clonal fidelity of the tissue culture-raised S. chirayita plantlets and corroborated the fact that axillary multiplication is the safest mode for multiplication of true to type plants.