Sacchi L, Nalepa C A, Bigliardi E, Lenz M, Bandi C, Corona S, Grigolo A, Lambiase S, Laudani U
Dipartimento di Biologia Animale, Università di Pavia, Italy.
Parassitologia. 1998 Sep;40(3):309-16.
All examined species of cockroaches have been shown to harbour intracellular bacteria in specialized cells (bacteriocytes) of the fat body. In termites, bacteria in specialized cells have been observed only in Mastotermes darwiniensis (Isoptera: Mastotermitidae). All of these bacteria have been assigned to the same eubacterial lineage, with the bacteria of M. darwiniensis as the sister group to the cockroach bacteria. While the main steps of the life cycle of cockroach bacteria have been described, little is known about the bacteria of M. darwiniensis. More specifically, no data are available on their behaviour during the development of this termite. Using both optical and electron microscopy methods, we examined embryos of M. darwiniensis at different developmental stages. Our results show that the integration of bacteria during the development of M. darwiniensis is implemented in the same way as in cockroaches. In particular, we observed the aggregation of a large amount of bacteria in a single mass in the yolk sac, with vitellophage-associated bacterial lysis. In cockroaches, a similar process has been described in detail for Periplaneta americana (Blattaria: Blattidae), where the bacterial mass is referred to as the transitory mycetome. The formation of a transitory mycetome could thus be regarded as an ancestral condition for cockroaches and termites.
所有被检测的蟑螂物种都已被证明在脂肪体的特殊细胞（含菌细胞）中携带细胞内细菌。在白蚁中，仅在达尔文澳白蚁（等翅目：澳白蚁科）的特殊细胞中观察到细菌。所有这些细菌都被归为同一真细菌谱系，其中达尔文澳白蚁的细菌是蟑螂细菌的姐妹群。虽然蟑螂细菌生命周期的主要步骤已被描述，但对于达尔文澳白蚁的细菌却知之甚少。更具体地说，关于这些细菌在这种白蚁发育过程中的行为尚无数据。我们使用光学和电子显微镜方法，检查了不同发育阶段的达尔文澳白蚁胚胎。我们的结果表明，达尔文澳白蚁发育过程中细菌的整合方式与蟑螂相同。特别是，我们观察到卵黄囊中大量细菌聚集形成一个团块，伴有与卵黄噬菌作用相关的细菌裂解。在蟑螂中，对于美洲大蠊（蜚蠊目：蜚蠊科）已经详细描述了类似的过程，其中细菌团块被称为临时菌瘤。因此，临时菌瘤的形成可被视为蟑螂和白蚁的一种原始状态。
