Intranuclear virus-like particles of a Drosophila hybrid

Intranuclear virus-like particles (VLPs) have been observed in different cell lines and adult tissues of Drosophila. In the present study, intranuclear VLPs have been found in larval tissues (salivary glands, midgut, fat body) as well as in adult tissues (midgut, genitals, fat body) of a rare interspecific hybrid (D. mauritiana x D. melanogaster) called 'mame'. The intranuclear VLPs were round or slightly elliptical with a diameter of 30 nm, and they were found mainly in highly organised clusters, forming large crystalline arrays, near the nucleolus and the polycene chromosomes. These particles were never observed in the cytoplasm of any mame's tissue. A few VLPs were also seen in the corresponding tissues of D. melanogaster, but they were never observed in any tissue of D. mauritiana. There is the intriguing possibility that these VLPs are related to transposable elements and probably contribute to the speciation process, in an unknown, so far, manner.