Isolation and characterization of 15 SSR loci for the endangered European tetraploid species Gladiolus palustris (Iridaceae).

PREMISE: Gladiolus palustris (Iridaceae) is an endangered European perennial tetraploid herb with special conservation interest in the European Union. Microsatellite markers can serve as effective tools for the conservation genetics of this species. METHODS AND RESULTS: We utilized a 454 pyrosequencing approach to identify simple sequence repeat (SSR) regions in a microsatellite-enriched library. Of all SSR regions, 46 were screened for specific PCR amplification, and 15 were found to be applicable in the target species. We found 1.62-3.08 alleles per population (effective alleles: 1.58-2.08) that indicated moderate to high genetic diversity values (0.28-0.44) in three pilot populations. Cross-species amplification was less effective in G. imbricatus and G. tenuis. CONCLUSIONS: The primers reported here can be used for the population genetic characterization of G. palustris. They will help us to better understand the conservation genetics of this highly endangered species.

Insulin/IGF Signaling and Life History Traits in Response to Food Availability and Perceived Density in the Cnidarian Hydra vulgaris.

Insulin/insulin-like growth factor signaling (IIS) is thought to be a central mediator of life history traits, but the generality of its role is not clear. Here, we investigated mRNA expression levels of three insulin-like peptide genes, the insulin-like receptor htk7, as well as several antioxidant genes, and the heat-shock protein hsp70 in the freshwater cnidarian Hydra vulgaris. Hydra polyps were exposed to a combination of different levels of food and perceived population density to manipulate life history traits (asexual reproduction and oxidative stress tolerance). We found that stress tolerance and the rate of asexual reproduction increased with food, and that these two effects were in significant interaction. Exposing animals to high perceived density resulted in increased stress tolerance or reduced reproduction only on lower food levels, but not on high food. The insulin-like receptor htk7 and the antioxidant gene catalase were significantly upregulated in the high density treatments. However, the expression level of insulin-like peptide genes, most antioxidant genes, and hsp70 were not affected by the experimental treatments. The higher expression level of htk7 may suggest that animals maintain a higher level of preparedness for insulin-like ligands at high population densities. However, the lack of difference between food levels suggests that IIS is not involved in regulating asexual reproduction and stress tolerance in hydra, or that its role is more subtle than a simple model of life history regulation would suggest.