Spiroplasma poulsonii sp. nov., a new species associated with male-lethality in Drosophila willistoni, a neotropical species of fruit fly

Abstract

Progenies from some wild-caught females of Drosophila willistoni and three other sibling species are entirely female. The proclivity for production of unisexual female progeny by these flies was named the sex ratio (SR) trait and was originally thought to be genetic. However, experiments in the laboratory of Donald F. Poulson in the early 1960s demonstrated that this 'trait' was vertically transmitted and infectious, in that it could be artificially transferred by injection from infected females to non-infected females. Motile, helical micro-organisms were observed in females showing the trait. In 1979, the SR organisms were designated as group II in the informal spiroplasma classification system. The organisms proved to be extremely fastidious, but were eventually cultivated in a very complex cell-free medium (H-2) after initial co-cultivation with insect cells. Cultivation in the H-2 medium and the subsequent availability of a triply cloned strain (DW-19 permitted comparative studies. Cells of strain DW-lT were helical, motile filaments 200-250 nm in diameter and were bound by a single trilaminar membrane. Cells plated on 1.8% Noble agar formed small satellite-free colonies 60-70 pm in diameter with dense centres and uneven edges. The temperature range for growth was 26-30 "C; optimum growth occurred a t 30 "C, with a doubling time in H-2 medium of 15.8 h. The strain passed through filters with 220 nm, but not 100 nm, pores. Reciprocal serological comparisons of strain DW-lT with representatives of other spiroplasma groups showed an extensive pattern of one-way crossing when strain DW-lT was used as antigen. However, variable, usually low-level reciprocal cross-reactions were observed between strain DWlT and representatives of group I sub-groups. The genome size of strain DW-lT was 2040 kbp, as determined by PFGE. The G+C content was 2621 mol%, as determined b y buoyant density and melting point methods. The serological and molecular data indicate that strain DW-lT is separated from group I representative strains sufficiently to justify retention of its group status. Continued group designation is also indicated by the ability of SR spiroplasmas to induce male lethality in Drosophila, their vertical transmissibility and their extremely fastidious growth requirements. Group II spiroplasmas, represented by strain DW-lT (ATCC 431 533, are designated Spiroplasma poulsonii.

Use of oxytetracycline for the treatment of tremor disease in the Chinese mitten crab Eriocheir sinensis

“…The agent can pass through membrane filters with pores of 220 nm diameter and can be cultivated in M1D or R2 media in vitro (Tully et al 1977, Whitcomb 1983, Hackett et al 1987, Moulder et al 2002. It is a helical, motile, disease-causing genus of bacteria first found in insects and plants in the 1970s (Saglio et al 1973, Clark 1982, Williamson et al 1999, Christensen et al 2005. Honeybee studies provided information on the prevention of spiroplasma-induced crawling disease with antibiotics; these studies made it apparent that spiroplasmas are susceptible to tetracycline.…”

Heritable Endosymbionts of Drosophila

“…With few exceptions (Yamada et al 1982;Ebbert 1991), strains of S. poulsonii cause son killing in D. willistoni, D. nebulosa, D. melanogaster, D. neocardini, D. paraguayensis, and D. ornatifrons and in species to which they have been artificially transferred (Williamson and Poulson 1979;Ebbert 1991Ebbert , 1995Williamson et al 1999;Montenegro et al 2005Montenegro et al , 2006. Our preliminary results suggest that its close relative, haplotype 1, does not cause son killing in D. hydei; D. hydei was previously reported (Ota et al 1979) to harbor a non-male killing strain of unknown relationship to the Spiroplasma of our study.…”

“…The only other heritable symbiont group reported for Drosophila species is Spiroplasma (Williamson and Poulson 1979;Williamson et al 1999;Montenegro et al 2005Montenegro et al , 2006, which, along with related bacteria in the phylum Mollicutes, is widespread in insect hosts (Gasparich 2002) and which sometimes causes son killing in infected females Montenegro et al 2005;Veneti et al 2005). In Drosophila, Spiroplasma infections are currently documented in five species of the subgenus Sophophora-D. melanogaster (Montenegro et al 2005); D. willistoni, D. nebulosa, D. paulistorum, and D. equinoxialis (Williamson and Poulson 1979;Williamson et al 1999); and four species of the subgenus Drosophila-D. hydei (Ota et al 1979); and D. neocardini, D. paraguayensis, and D. ornatifrons (Montenegro et al 2006).…”

“…In Drosophila, Spiroplasma infections are currently documented in five species of the subgenus Sophophora-D. melanogaster (Montenegro et al 2005); D. willistoni, D. nebulosa, D. paulistorum, and D. equinoxialis (Williamson and Poulson 1979;Williamson et al 1999); and four species of the subgenus Drosophila-D. hydei (Ota et al 1979); and D. neocardini, D. paraguayensis, and D. ornatifrons (Montenegro et al 2006).…”

Spiroplasma atrichopogonis sp. nov., from a ceratopogonid biting midge

“…Of these isolates, several have been shown to be pathogens to their insect hosts, whereas others are commensals (Hackett & Clark, 1989;Clark, 1982;Clark et al, 1984). In the order Diptera, spiroplasmas have been isolated from fruit flies (Drosophilidae) (Williamson et al, 1999), several genera of mosquitoes (Culicidae) (Chastel & Humphery-Smith, 1991), a hover fly (Syrphidae) , and from several genera of deer and horse flies (Tabanidae) (Whitcomb et al, 1997). The success of isolations from dipteran hosts led to the investigation of biting and predaceous midges (Ceratopogonidae) as spiroplasma hosts.…”