Streptococcal L-forms isolated from Drosophila paulistorum semispecies cause sterility in male progeny.

The Drosophila paulistorum complex contains six semispecies that do not normally interbreed. In the laboratory, crosses between semispecies produce fertile daughters and sterile sons. Microbial endosymbionts have been observed in all D. paulistorum flies that display this male sterility. Streptococcal L-forms have been isolated from the Andean-Brazilian (Mesitas) and Transitional (Santa Marta) semispecies and cultured in artificial medium. Transfer of these L-forms from their native hosts into reciprocal semispecies resulted in sterile male progeny. When L-forms were inoculated into the semispecies from which they had been isolated, most of the male progeny were fertile. Control streptococcal L-forms did not show this sterility pattern.

Characteristics of the Drosophila paulistorum Male Sterility Agent in a Secondary Host, Ephestia kuehniella.

Crosses among the six semispecies of Drosophila paulistorum produce sterile male hybrids. This sterility is caused by an agent which has characteristics of a microorganism. It is pathogenic in a secondary host, the larvae of the Mediterranean meal moth, Ephestia kuehniella, and can be serially passaged in Ephestia, where it is lethal. The agent was passaged back into D. paulistorum, where it induced sterility in males of a semispecies different from that of origin of the agent. Infectious particles were obtained from an extract of infected Ephestia by ultracentrifugation in a sucrose-Ficoll-metrizamide gradient. Both crude and purified extracts were lyophilized and stored indefinitely without loss of killing power. The agent was destroyed by low pH, lipid solvents, ultraviolet light, and exposure to a temperature of 56 degrees C for 30 min. It appeared to be sensitive to tetracycline and insensitive to penicillin, suggesting that the agent is not a virus, but more likely a cell wall-deficient bacterium or mycoplasma-like organism.

Spore germination, colony development, and secondary metabolism in Penicillium brevicompactum: a radiogas chromatographic and morphological study.

A study of the first 76 h of development of spores of Penicillium brevicompactum in batch-mode shake culture indicates that mycophenolic acid biosynthesis begins when the hyphae of germinating spores aggregate to form pellets. Supplies of mycophenolic acid so produced augment a pre-existing pool of the material that is associated with the dormant spore. Although acetate metabolism is active at all stages of development, incorporation of [1-(14)C]acetate into 2,4-dihydroxy-6-(1',2'-dioxopropyl)benzoic acid, another secondary metabolite of the fungus, could not be demonstrated. The significance of these data are considered in terms of the function of mycophenolic acid and the substituted benzoic acid in the producing organism.

A unique cause of female sterility inDrosophila melanogaster.

Histological studies do not permit the distinction between an oocyte, ovary or oviduct malformation as the primary cause of sterility in females homozygous for the Hairywing 49c allele inDrosophila melanogaster. Reciprocal transplantations of larval ovaries between homozygous mutant larvae and normal larvae demonstrate that the sterility is due to a malfunctioning of the oviduct, presumably at the junction of the common oviduct and the uterus. This failure of the oviduct to function normally appears to represent a unique cause of female sterility in this organism.