The ultrastructure of malpighian tubules and the chemical composition of the cocoon of Aeolothrips intermedius Bagnall (Thysanoptera)
ABSTRACT The secretory activity of the two branched malpighian tubules (MTs) of the second-instar larva in Aeolothrips intermedius is described. MTs of adult thrips have the typical ultrastructure of excretory epithelium with apical microvilli containing long mitochondria and a rich system of basal membrane infoldings. In the second-instar larva just before pupation, the ultrastructure of MT epithelial cells is dramatically different, and there are numerous huge Golgi systems in the cytoplasm. These cells are involved in an intense secretory activity to produce an electron-dense product which is released into the MTs lumen. This secretion is extruded from the hindgut and used by the second-instar larva to build an elaborate protective cocoon for pupation. Electron-spray-ionization mass spectrometry analysis of the cocoon revealed the presence of a beta-N-acetyl-glucosamine, the main component of chitin, which is also present in the cocoons of Neuroptera and some Coleoptera.
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ABSTRACT: Spermatogenesis and the sperm structure of the terebrantian Aeolothrips intermedius Bagnall are described. Spermatogenesis consists of two mitotic divisions; the second is characterized by the loss of half of the spermatids, which have pyknotic nuclei. Early spermatids have two centrioles, but when spermiogenesis starts, a third centriole is produced. The three basal bodies give rise to three flagella; later these fuse into a single flagellum which contains three 9+0 axonemes. The basal bodies are surrounded by a large amount of centriole adjunct material. During spermiogenesis this material contributes to the shifting of the three axonemes towards the anterior sperm region parallel to the elongating nucleus, and it is transformed into a dense cylinder. In the mature spermatids the three axonemes amalgamate to create a bundle of 27 doublet microtubules. Near the end of spermiogenesis the dense cylinder of the centriole adjunct lies parallel to the nucleus and the axonemes. It ends where the mitochondrion appears at half-sperm length. We confirm that Terebrantia testes have a single sperm cyst; their sperm are characterized by a cylindrical nucleus, three axonemes fused into one, a small mitochondrion and a short cylindrical centriole adjunct which corresponds to the dense body described in a previous work. The acrosome is lacking. At the midpoint of the anterior half of the sperm the outline of the cross-section is bilobed, with the nucleus contained in a pocket evagination of the plasma membrane. These characters are discussed in light of a comparison between Tubulifera and Terebrantia.Tissue and Cell 08/2010; 42(4):247-58. DOI:10.1016/j.tice.2010.04.008 · 1.05 Impact Factor