Gomes Guilherme, Silva-Zacarin Elaine C M, Zara Fernando J, Silva de Moraes Regina L M, Caetano Flávio H
Departamento de Biologia, Instituto de Biociências, Universidade Estadual Paulista, Rio Claro, SP, Brasil.
Genet Mol Res. 2004 Sep 30;3(3):309-22.
The cocoon, produced by most holometabolous insects, is built with silk that is usually produced by the larval salivary gland. Although this silk has been widely studied in the Lepidoptera, its composition and macromolecular arrangement remains unknown in the Hymenoptera. The macromolecular array patterns of the silk in the larval salivary gland of some meliponids, wasps, and ants were analyzed with polarized-light microscopy, and they were compared with those of Bombyx mori (Lepidoptera). There is a birefringent secretion in the glandular lumen of all larvae, due to filamentous structural proteins that display anisotropy. The silk in the distal, middle and proximal regions of the secretory portion of Formicidae and Vespidae glands presented a lattice optical pattern. We found a different pattern in the middle secretory portion of the Meliponini, with a zigzag rather than a lattice pattern. This indicates that the biopolymer fibers begin their macromolecular reorganization at this glandular region, different from the Formicidae and the Vespidae, in which the zigzag optical pattern was only found at the lateral duct. Probably, the mechanism of silk production in the Hymenoptera is a characteristic inherited from a common ancestor of Vespoidea and Sphecoidea; the alterations in the pattern observed in the Meliponini could be a derived characteristic in the Hymenoptera. We found no similarity in the macromolecular reorganization patterns of the silk between the Hymenoptera species and the silkworm.
大多数全变态昆虫所产生的茧是由通常由幼虫唾液腺分泌的丝构建而成。尽管这种丝在鳞翅目中已得到广泛研究，但其组成和大分子排列在膜翅目中仍不为人所知。利用偏光显微镜分析了一些无刺蜂、黄蜂和蚂蚁幼虫唾液腺中丝的大分子排列模式，并将其与家蚕（鳞翅目）的进行了比较。由于丝状结构蛋白表现出各向异性，所有幼虫的腺腔内都有一种双折射分泌物。蚁科和胡蜂科腺体分泌部分的远端、中部和近端区域的丝呈现出晶格光学模式。我们在无刺蜂亚科的中部分泌部分发现了一种不同的模式，是之字形而非晶格模式。这表明生物聚合物纤维在这个腺体区域开始其大分子重组，这与蚁科和胡蜂科不同，在蚁科和胡蜂科中，之字形光学模式仅在侧管中发现。可能，膜翅目中丝的产生机制是从胡蜂总科和针尾部的共同祖先继承而来的特征；在无刺蜂亚科中观察到的模式变化可能是膜翅目中的一种衍生特征。我们发现膜翅目物种与蚕的丝的大分子重组模式没有相似之处。
