The metabolic enzyme locus Triosephosphate Isomerase (Tpi) in Drosophila melanogaster is sensitive to the pairing- dependent trans interaction transvection

Abstract

Recent advances in our ability to visualize and quantify interactions between chromosomes have made the study of these interactions a key step in advancing our understanding of gene regulation. A special form of trans interactions, called transvection, occurs when homologous chromosomes are physically paired in somatic cells. I have characterized interactions at the Triosephosphate isomerase (Tpi) locus, present on the third chromosome, in Drosophila melanogaster using a combination of enzymatic and transcriptional assays and a series of low activity Tpi alleles I generated. I found significant interactions in trans at Tpi which showed a dependence on pairing of homologous chromosomes, this dependence classifies the trans effects at Tpi as the special form of regulation, transvection. These transvection effects at Tpi are also sensitive to genetic background, where the excision alleles have different transvection effect interactions based on the variation of the third chromosome with which they are paired. The presence of transvection at Tpi provides a new locus at which to study chromosomal interactions and confirms previous results that pairing dependent interactions, in vivo, are subject to a number of complex regulatory elements.