Meeting Abstract

P1.77  Monday, Jan. 4  Lumbriculus variegatus Populations Show Variations in Chromosome Number, Protein Expression, Response to Toxicants, and Modes of Reproduction TWEETEN, Kay/A.; St. Catherine University katweeten@stkate.edu

Analysis of several North American populations of Lumbriculus variegatus revealed differences in chromosome numbers. Chromosome spreads from L. variegatus collected from natural habitats in Iowa and Minnesota contained 34-36 chromosomes. Spreads from L. variegatus reference populations that have been maintained for several years in laboratory cultures or that were obtained from commercial sources contained greater than 60 chromosomes, suggesting that the genomes of these worms are polyploid. Protein profiles generated by SDS-polyacrylamide gel electrophoresis were very similar for all the populations. Analysis of proteins by two-dimensional gel electrophoresis showed some differences in levels of expression of specific proteins between the diploid and polyploid populations. Whereas the polyploid populations only reproduced asexually, the populations collected from natural habitats reproduced asexually and sexually with cocoons yielding viable offspring. Because L. variegatus is used extensively as an environmental quality indicator organism, the response of the diploid and polyploid populations to environmental toxicants was determined. For interpretation and comparison of experimental or toxicological results using this freshwater oligochaete, the data suggest that it is important that researchers report the diploid or polyploid nature of their test organisms.