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三种夜蛾成虫口器感器的超微形态 总被引:1,自引:0,他引:1
为确定不同种类夜蛾口器及其感器在超微结构上的差异, 采用扫描电子显微镜对棉铃虫Helicoverpa armigera (Hübner)、 烟夜蛾H. assulta (Guenée)和银纹夜蛾Argyrogramma agnata (Staudinger)3种鳞翅目(Lepidoptera)夜蛾科(Noctuidae)重要农业害虫雌、 雄成虫口器感器的超微形态进行了观察和比较。结果表明: 3种夜蛾雌、 雄成虫口器感器类型均无明显差异。棉铃虫和烟夜蛾口器感器在类型和形状上十分类似, 均具有毛形、 锥形和栓锥形感器; 喙管末端的栓锥感器粗、 密, 棱纹明显。银纹夜蛾口器感器与两种铃夜蛾区别明显, 除上述3类感器外, 还具有腔锥形感器; 其喙管末端的栓锥感器细、 疏, 棱纹不明显。结果显示口器感器可用于夜蛾的分类及亲缘关系研究。 相似文献
994.
An integrated, bioinformatic analysis of three databases comprising tumor-cell-based small molecule screening data, gene expression measurements, and PDB (Protein Data Bank) ligand-target structures has been developed for probing mechanism of drug action (MOA). Clustering analysis of GI50 profiles for the NCI's database of compounds screened across a panel of tumor cells (NCI60) was used to select a subset of unique cytotoxic responses for about 4000 small molecules. Drug-gene-PDB relationships for this test set were examined by correlative analysis of cytotoxic response and differential gene expression profiles within the NCI60 and structural comparisons with known ligand-target crystallographic complexes. A survey of molecular features within these compounds finds thirteen conserved Compound Classes, each class exhibiting chemical features important for interactions with a variety of biological targets. Protein targets for an additional twelve Compound Classes could be directly assigned using drug-protein interactions observed in the crystallographic database. Results from the analysis of constitutive gene expressions established a clear connection between chemo-resistance and overexpression of gene families associated with the extracellular matrix, cytoskeletal organization, and xenobiotic metabolism. Conversely, chemo-sensitivity implicated overexpression of gene families involved in homeostatic functions of nucleic acid repair, aryl hydrocarbon metabolism, heat shock response, proteasome degradation and apoptosis. Correlations between chemo-responsiveness and differential gene expressions identified chemotypes with nonselective (i.e., many) molecular targets from those likely to have selective (i.e., few) molecular targets. Applications of data mining strategies that jointly utilize tumor cell screening, genomic, and structural data are presented for hypotheses generation and identifying novel anticancer candidates. 相似文献
995.
F plasmid TraM, an autoregulatory homotetramer, is essential for F plasmid bacterial conjugative transfer, one of the major mechanisms for horizontal gene dissemination. TraM cooperatively binds to three sites (sbmA, -B, and -C) near the origin of transfer in the F plasmid. To examine whether or not tetramerization of TraM is required for autoregulation and F conjugation, we used a two-plasmid system to screen for autoregulation-defective traM mutants generated by random PCR mutagenesis. A total of 72 missense mutations in TraM affecting autoregulation were selected, all of which also resulted in a loss of TraM function during F conjugation. Mutational analysis of TraM defined three regions important for F conjugation, including residues 3-10 (region I), 31-53 (region II), and 80-121 (region III); in addition, residues 3-47 were also important for the immunoreactivity of TraM. Biochemical analysis of mutant proteins indicated that region I defined a DNA binding domain that was not involved in tetramerization, whereas regions II and III were important for both tetramerization and efficient DNA binding. Mutations in region III affected the cooperativity of binding of TraM to sbmA, -B, and -C. Our results suggest that tetramerization is important for specific DNA binding, which, in turn, is essential for traM autoregulation and F conjugation. These findings support the hypothesis that TraM functions as a "signaling" factor that triggers DNA transport during F conjugation. 相似文献
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997.
Here we present the genomic sequence, with analysis, of a canarypox virus (CNPV). The 365-kbp CNPV genome contains 328 potential genes in a central region and in 6.5-kbp inverted terminal repeats. Comparison with the previously characterized fowlpox virus (FWPV) genome revealed avipoxvirus-specific genomic features, including large genomic rearrangements relative to other chordopoxviruses and novel cellular homologues and gene families. CNPV also contains many genomic differences with FWPV, including over 75 kbp of additional sequence, 39 genes lacking FWPV homologues, and an average of 47% amino acid divergence between homologues. Differences occur primarily in terminal and, notably, localized internal genomic regions and suggest significant genomic diversity among avipoxviruses. Divergent regions contain gene families, which overall comprise over 49% of the CNPV genome and include genes encoding 51 proteins containing ankyrin repeats, 26 N1R/p28-like proteins, and potential immunomodulatory proteins, including those similar to transforming growth factor beta and beta-nerve growth factor. CNPV genes lacking homologues in FWPV encode proteins similar to ubiquitin, interleukin-10-like proteins, tumor necrosis factor receptor, PIR1 RNA phosphatase, thioredoxin binding protein, MyD116 domain proteins, circovirus Rep proteins, and the nucleotide metabolism proteins thymidylate kinase and ribonucleotide reductase small subunit. These data reveal genomic differences likely affecting differences in avipoxvirus virulence and host range, and they will likely be useful for the design of improved vaccine vectors. 相似文献
998.
Multilayer biogenic capsules with a micrometer scale were fabricated by self-assembly of proteins and lipids at the interface of emulsion droplets. The optical microscopy images demonstrate that spherical capsules at a fluid interface have uniform walls and the dried capsules possess a high mechanical strength. The hollow shells obtained provide a novel class of assembly with encapsulating drug molecules based on the layer-by-layer technique. 相似文献
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1000.