Meeting Abstract

81.6  Monday, Jan. 6 11:30  Within-species variation and phylogenetic patterns in anti-bacterial activity in egg masses of 16 mollusc species SMOOT, SC*; PLANTE, CJ; PODOLSKY, RD; College of Charleston scsmoot@gmail.com

Gelatinous egg masses are used by several species of marine invertebrates to encapsulate embryos until hatching. The high protein and mucopolysaccharide content of these egg masses make them particularly hospitable to microbial growth and therefore susceptible to infection. Previous studies have isolated chemical compounds from egg masses that deter bacterial infection, but have not examined quantitative differences among species or the effects of environmental variation on these defenses. We compared the anti-bacterial activity of egg masses from 16 sympatric molluscan species or species groups that varied in ecological habitat and deposition substrate. Egg masses were extracted with non-polar ethyl acetate (EtOAc) and polar methanol (MeOH) solvents and then tested for anti-bacterial activity against the Gram-negative bacterium Vibrio harveyi and Gram-positive Bacillus subtilis in a 96-well plate growth assay. In addition to large differences among species in anti-bacterial activity we also found within-species variation tied to habitat type and deposition substrate. Furthermore, we detected a phylogenetic signal at higher taxonomic levels, with cephalaspids showing the highest level of anti-bacterial activity and nudibranchs showing surprisingly low levels. A randomization test found a significant difference between the cephalaspids and nudibranchs in the activity both extracts against V. harveyi but not against B. subtilis. These results suggest wide interspecific and intraspecific variation in the degree of anti-bacterial protection in embryo encapsulating structures. Levels of anti-bacterial protection appear to depend both on phylogeny and on environmental conditions at small and large spatial scales.