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1.
Volatile components of field- and glass greenhouse-grown tomatoes(Lycopersicon esculentum MILL., variety, V. R. Moscow) of differentmaturities were studied by gas-liquid and thin-layer chromatography.The following components were separated and identified: isobutylalcohol, isopentyl alcohol, hexyl alcohol, 2-methyl-3-hexanol,isovaleraldehyde, caproaldehyde, benzaldehyde, furfural, isopentylacetate, isopentyl butyrate, isopentyl isovalerate, butyl hexanoate,hexyl hexanoate, methyl salicylate and -pinene. Chromatogramswere consistent for both field- and greenhouse-grown tomatoesat all stages of maturity. Except for isovaleraldehyde and hexylalcohol, the biosynthesis of volatile components increased alongwith the growth of fruit. Isovaleraldehyde and hexyl alcohol,presumed to give the "green leafy" aroma of tomatoes, were foundto be in their highest concentrations at the breaker and thelarge-green stages, respectively.
1This research was supported by a research grantUI 00449fromthe National Center for Urban and Industrial Health, U. S. PublicHealth Service. 相似文献
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Bioinsecticides are important in the control of disease vectors, but data regarding their physiological effects on target insects are incomplete. This study describes morphological changes that occur in the midgut of third instar Aedes aegypti L. (Diptera: Culicidae) following treatment with a methanolic extract of Annona coriacea (Magnoliales: Annonaceae). Dissected midguts were subdivided into anterior and posterior regions and analyzed by light and scanning electron microscopy. Insects exposed to the extract displayed intense, destructive cytoplasmic vacuolization in columnar and regenerative midgut cells. The apical surfaces of columnar cells exhibited cytoplasmic protrusions oriented toward the lumen, suggesting that these cells could be involved in apocrine secretory processes and/or apoptosis. We report that A. coriacea extracts induced morphological alterations in the midgut of A. aegypti midgut larvae, supporting the use of plant extracts for control of the dengue vector. 相似文献
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越南铁线莲属一新种 总被引:3,自引:0,他引:3
Nguyen Yhi DO 《植物分类学报》2006,44(5):595-597
本文描述的产于越南的毛茛科Ranunculaceae铁线莲属Clematis一新种C. hagiangensis N. T. Do是欧亚大陆第一个具单性花的种, 在花构造方面与单性铁线莲组单性铁线莲亚组sect. Aspidanthera Spach subsect. Dioicae (Prantl) W. T. Wang的种类近缘, 但叶均为单叶, 萼片呈卵形或宽卵形而不同。在单性铁线莲亚组的种, 叶通常为复叶, 只在C. dimorphophylla W. T. Wang和C. variifolia W. T. Wang同时为单叶和复叶, 此外萼片呈长圆形、倒披针形或狭卵形。 相似文献
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报道了7个楼梯草属和赤车属植物(荨麻科)新纪录,它们分别为锐齿楼梯草(E. cyrtandrifolium),变黄楼梯草(E. xanthophyllum),对叶楼梯草(E. sinense),宽叶楼梯草(E. platyphyllum),托叶楼梯草(E. nasutum),短叶赤车(P. brevifolia)和华南赤车(P. grijsii)。列出了各个物种的标本引证和地理分布情况。 相似文献
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Yamamoto M Kamata T DO ND Adachi Y Kinjo M Ando T 《Bioscience, biotechnology, and biochemistry》2007,71(11):2860-2863
Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produced three pheromone components (I-III), which strongly stimulated male antennae. Using GC-MS analysis and chemical derivatizations, the following structures were estimated: 6-methyl-2-octadecanone (I), 14-methyl-2-octadecanone (II), and 6,14-dimethyl-2-octadecanone (III). While the stereochemistry of the chiral centers could not be determined because it was difficult to collect a sufficient amount of the natural pheromone, the plain structures of I and II were confirmed by synthesis of the racemic mixtures starting from diols. These methyl-branched ketones have not been identified as a natural product, indicating that they constitute a new chemical group of lepidopteran female sex pheromones. 相似文献
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Antson AA 《Current opinion in structural biology》2000,10(1):87-94
Our knowledge of protein interactions with RNA molecules has been, so far, largely restricted to cases in which the RNA itself is folded into a secondary and/or tertiary structure stabilised by intramolecular base pairing and stacking. Until recently, only limited structural information has been available about protein interactions with single-stranded RNA. A breakthrough in our understanding of these interactions came in 1999, with the determination of four crystal structures of protein complexes with extended single-stranded RNA molecules. These structures revealed wonderfully satisfying patterns of the ability of proteins to accommodate RNA bases, with the sugar-phosphate backbone often adopting conformations that are different from the classical double helix. 相似文献
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We examined the phylogenetic relationships among five heterothallic species of Neurospora using restriction fragment polymorphisms derived from cosmid probes and sequence data from the upstream regions of two genes, al-1 and frq. Distance, maximum likelihood, and parsimony trees derived from the data support the hypothesis that strains assigned to N. sitophila, N. discreta, and N. tetrasperma form respective monophyletic groups. Strains assigned to N. intermedia and N. crassa, however, did not form two respective monophyletic groups, consistent with a previous suggestion based on analysis of mitochondrial DNAs that N. crassa and N. intermedia may be incompletely resolved sister taxa. Trees derived from restriction fragments and the al-1 sequence position N. tetrasperma as the sister species of N. sitophila. None of the trees produced by our data supported a previous analysis of sequences in the region of the mating type idiomorph that grouped N. crassa and N. sitophila as sister taxa, as well as N. intermedia and N. tetrasperma as sister taxa. Moreover, sequences from al-1, frq, and the mating-type region produced different trees when analyzed separately. The lack of consensus obtained with different sequences could result from the sorting of ancestral polymorphism during speciation or gene flow across species boundaries, or both. 相似文献