Duplication of an Hsp70 gene in isolates of the colonizer nematode species Acrobeloides nanus may suggest genome plasticity NIKOLAS NIKOLAIDIS1§, ELENA DROSOPOULOU1, GEORGE P. STAMOU2 and ZACHARIAS G. SCOURAS1* 1 Department of Genetics, Development and Molecular Biology, School of Biology, Aristotle University, Thessaloniki, 54 124, Greece 2 Department of Ecology, School of Biology, Aristotle University, Thessaloniki, 54 124, Greece Abstract Acrobeloides nanus is a dynamic colonizer nematode species, which exhibits high ecological plasticity. The purpose of this study was to investigate the genomic plasticity in A. nanus by examining the genomic divergence of a 70-kilodalton heat shock protein gene among different isolates of the species. Southern-blot hybridization experiments using as a probe the hsp70-1 sequences of Caenorhabditis elegans, resulted in two different hybridization patterns for the A. nanus isolates. Pattern I was similar to that of C. elegans. Pattern II showed two additional hybridization signals which apparently represent duplication(-s) of the hsp70-1 locus in A. nanus. The A. nanus isolates were further differentiated by the variable size of the first intron of the hsp70-1 gene. This genomic variation in both neutral and under selection regions of the hsp70 genes reflects an extensive genomic plasticity in A. nanus, which could be correlated with the plasticity in ecology and adaptation of this opportunistic nematode species.   < back .