On the Giant Octopus (Octopus giganteus) and the Bermuda Blob: Homage to A. E. Verrill

Volume: 188Start Page: 219End Page: 23

The hazards of love: Sterilization and lethality in interspecies crosses

Because sexual selection is weak in selfing species, hermaphrodites may evolve greater susceptibility to the harmful effects of mating. In addition, more specific ‘gene-for-gene’ mismatches might also be evident in interspecies crosses, even between species with the same reproductive mode. We examined heterospecific matings between and within a given sexual mode. Hermaphrodites of C. briggsae, C. elegans, and C. sp. 11 mated to gonochoristic males produce far fewer self-progeny than controls. In C. briggsae, one mating with a gonochoristic male is sufficient for sterilization, and this is likely due to premature oocyte maturation. C. sp. 9 males also greatly accelerate the mortality of C. briggsae hermaphrodites. Dying hermaphrodites often have sperm outside of the uterus and spermatheca (“sperm metastasis”). Germline-feminized C. sp. 9 males deposit copulatory plugs, but fail to sterilize or reduce the lifespan of C. briggsae hermaphrodites, indicating sperm are necessary for both effects. These patterns of asymmetrical sterilization and mortality are also evident in crosses between selfing and gonochoristic Pristionchus species. Matings between different hermaphroditic or gonochoristic species also reduce brood sizes, but to a lesser extent. Collectively, our findings are consistent both with a general ‘weak inbreeder’ susceptibility of hermaphrodites in matings with males of outcrossing species, and with mating system-independent accumulation of reproductive incompatibilities. The latter may represent resolutions of species-specific conflicts that do not ‘complement’ each other in interspecific crosses. Sperm size differences between sexes and species may also contribute. The relaxation of the evolutionary arms race between males and females in hermaphrodites may make them especially susceptible to harm by gonochoristic males. This could accelerate and/or reinforce reproductive isolation between hermaphroditic species and outcrossing relatives

Annual Viral Expression in a Sea Slug Population: Life Cycle Control and Symbiotic Chloroplast Maintenance

Volume: 197Start Page: 1End Page:

Idiomarina gen. nov., comprising novel indigenous deep-sea bacteria from the Pacific Ocean, including descriptions of two species, Idiomarina abyssalis sp nov and Idiomarina zobellii sp nov.

Two bacterial strains, KMM 227(T) and 231(T), were isolated from seawater samples collected from the north-western Pacific Ocean at a depth of 4000-5000 m and were characterized using polyphasic taxonomy, Both were Gram-negative, psychrotolerant, heterotrophic, aerobic and required NaCl for growth (0.6-15.0%). The temperature for growth was 4-30 degrees C. Both strains were rod-shaped, with a single flagellum, However, strain KMM 231(T) revealed a single long fimbrium, Cellular fatty acids detected in the isolates were predominantly odd-numbered and iso-branched, with 15 and 17 carbons (ca. 70%), Also present were saturated and monounsaturated straight-chain fatty acids. Results of phylogenetic analyses, employing three tree-making methods, strongly indicated that the two strains formed a distinct lineage within a clade containing the genera Alteromonas, Colwellia and Pseudoalteromonas. in the gamma-Proteobacteria, The two strains shared 16S rDNA sequence similarity of 96.9% and genomic DNA relatedness of 27%; the latter was determined by dot-blot hybridization, The strains were differentiated by the presence of fimbria, production of chitinase, ability to grow on 15% NaCl and BIOLOG profiles. Given the polyphasic evidence accumulated in this study, it is proposed that the two deep-sea isolates be classified in the genus Idiomarina gen, nov., as Idiomarina abyssalis sp, nov. (type strain is KMM 227(T)) and Idiomarina zobellii sp, nov. (type strain is KMM 231(T)).