Tuesday January 13th, 15.35 in C-147

Michael A. Herman (Ecological Genomics Institute, Kansas State University)

Abstract:

Determining the genetic mechanisms involved in organismal response to environmental change is essential for understanding the effects of anthropogenic disturbance. This can be challenging, as well developed genomic tools exist for only a few organisms.  We are using resident soil nematode populations sampled from the Konza Prairie Biological Station, near Manhattan, Kansas, to link the responses of organisms to environmental change at the genetic level.As nematodes are among the most abundant invertebrates in soils and respond quickly to changing environmental conditions, they are ideal organisms to assess the potential impacts of environmental change on soil communities.We have focused on microbial-feeding nematodes because of their important role in soil communities and to take advantage of the genomic tools available in the model soil nematode Caenorhabditis elegans. Both the microbial-feeding nematode and bacterial communities differentially respond to altered disturbance regimes (i.e., changes in fire frequency) and nutrient enrichment.We then used transcriptional profiling in C. elegansto identify candidate genes regulated in response to bacteria isolated from grassland soils. Many of the regulated candidate genes are predicted to effect metabolism and innate immunity. Using mutations that inactivate many of the identified genes, we showed that most contribute to fitness and/or defense in a given bacterial environment.Interestingly, the defense response was not specific to C. elegans as we have found a variety of pathogen-associated effects in native nematode taxa in response to the native bacterial isolates.Overall our results suggest that soil nematode fitness in a given bacterial environment in part depends upon the regulation of metabolic and defense functions that modulate trophic and pathogenic interactions with bacteria.