RT Journal Article SR Electronic(1) A1 Lécher, Pierre A1 Bucheton, Alain A1 Pélisson, AlainYR 1997 T1 Expression of the Drosophila retrovirus gypsy as ultrastructurally detectable particles in the ovaries of flies carrying a permissive flamenco allele JF Journal of General Virology, VO 78 IS 9 SP 2379 OP 2388 DO https://doi.org/10.1099/0022-1317-78-9-2379 PB Microbiology Society, SN 1465-2099, AB The endogenous retrovirus gypsy is controlled by the Drosophila gene flamenco (flam). New insertions of gypsy occur in any individual Drosophila if its mother is homozygous for the flam 1 permissive allele and contains functional gypsy proviruses. The ovaries of flam 1 females also contain high amounts of gypsy RNAs. Unexpectedly however, gypsy derepression does not occur in the flam 1 female germline proper but in the somatic follicular epithelium of the ovary. Since extracts from these females are able to efficiently infect the germ-line of a strain devoid of active gypsy proviruses, we assume that a similar kind of germ-line infection, which would occur inside the flam 1 females themselves, could be required for gypsy insertions to occur in their progeny. This hypothesis was confirmed by electron microscopy observations showing that non-enve-loped intracytoplasmic particles containing gypsy RNAs accumulate in the apical region of the flam 1 follicle cells, close to specific membrane domains to which the gypsy envelope proteins are targeted, whereas both are absent in the flam controls. Low amounts of similar virus-like particles were also observed in flam 1 oocytes, but it is not yet known whether they entered passively or as a result of membrane fusion. This is the first report of the beginning of a retrovirus cycle in invertebrates and these observations should be taken into account when explaining the maternal effect of the flamenco gene on the multiplication of gypsy proviruses., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-78-9-2379