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白蚁的外部形态和分类系统   总被引:5,自引:1,他引:4       下载免费PDF全文
等翅目Isoptera(白蚁)在有翅昆虫亚纲进化的谱系中是属于一类比较原始的昆虫,与蜚蠊目Blattaria昆虫有比较密切的亲缘关系。 白蚁有翅成虫的头部形态、前后翅的等同、翅脉的复杂结构以及腹部的形态,都和低等的有翅昆虫或古代绝灭的昆虫相类似。但白蚁的生活习性和兵蚁的形态特征,在整个昆虫纲中是属于极为进化的一个类群。兵蚁的形态极为特化。双眼的退化、前后翅的  相似文献
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本文对有关昆虫特征的类型和应用作了初步分析,将特征归纳为“独自性”和“系统性”两大类。指出祖征的拥有存在着三个方面的不均衡。一个类群拥有比较多而典型的祖征,属于接近祖先的类群;反之,拥有较少而变型的祖征,则属于后起的类型。一般说来,同级阶元非独立拥有的特征不宜作为系统依据。在研究白蚁形态“原始型”和“蜕变型”的基础上,强调“蜕变型”作为衍征在研究等翅目各科系统关系的意义。  相似文献
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SARS-CoV M gene fragment was cloned and expressed as a recombinant protein fused with a V5 tag at the C-terminus in Vero E6 cells. In addition to un-glycosylated and glycosylated proteins, one product with smaller size initiated in-frame from the third Met residues probably through ribosomal re-initiation was also detected. Translation initiated in-frame from the third Met is unusual since the sequence around the first Met of SARS-CoV M protein contains the optimal consensus Kozak sequence. The function of this smaller translated product awaits further investigation. Similar to other N-glycosylated proteins, glycosylation of SARS-CoV M protein was occurred co-translationally in the presence of microsomes. The SARS-CoV M protein is predicted as a triple-spanning membrane protein lack of a conventional signal peptide. The second and third trans-membrane regions (a.a. 46–68 and 78–100) are predicted to be the primary type helices, which will be able to penetrate into membrane by themselves, while the first trans-membrane region (a.a. 14–36) is predicted to be the secondary type helix, which is considered to be stabilized by the interaction with other trans-membrane segments. As expected, the second and third trans-membrane regions were able to insert a cytoplasmic protein into the endoplasmic reticulum membrane more efficiently than the first one. These results should be important for the study of SARS-CoV morphogenesis. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献
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