Phylogenetically distant endocytobionts in termites:
Wolbachia and Blattabacterium
1Bandi C., 2Grigolo A., 2Sacchi L.
1Istituto di Patologia Generale Veterinaria, Università di Milano, Via Celoria 10, 20133 Milano, Italy; 2Dipartimento di Biologia Animale, Università di Pavia, Piazza Botta 9, 27100 Pavia, Italy;
Cockroaches harbour intracellular bacteria in specialised cells (mycetocytes) of the fat body. In termites, mycetocyte bacteria have been observed only in Mastotermes darwiniensis. These bacteria share similar mechanisms for transovarial transmission, have been assigned to the same eubacterial lineage, and are thought to have originated from a bacterium that infected an ancestor common to cockroaches and termites [1]. Thus, loss of the infection should have occurred during evolution in termite lineages, with the exception of the lineage which gave rise to M. darwiniensis. Traces of the ancient infection may however be present in some termites, in the form of non-mycetocyte intracellular bacteria (e.g. a small number of bacteria within normal cells). Indeed, circumstantial evidence for the presence of intracellular bacteria in some termite species has been reported since 1946. A recent study on this subject showed that non-mycetocyte intracellular bacteria are widespread in termites, and can be observed in the cytoplasm and the nuclei of both reproductive and somatic tissues. In addition, sequence analysis of the 16S rRNA and ftsZ genes indicated that at least some of the non-mycetocyte bacteria of termites belong to the Wolbachia group of the alpha-2 subclass of the proteobacteria. These latter bacteria are not related to the mycetocyte bacteria of cockroaches and M. darwiniensis, which belong to the blattabacterium group of the flavobacteria-bacteroides. The origins of the two (at least) kinds of intracellular bacteria of termites should thus be regarded as independent. A PCR screening with primers specific for Wolbachia confirmed the widespread diffusion of this bacterium in termites [2].
[1] Bandi et al. (1995) Proc. R. Soc. Lond. B 259: 293-299
[2] Bandi et al. (1997) Parasitologia 39: 71-75
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Thursday, April 9 |
09:25 am |