CHARACTERIZATION OF TELOMERASE EXPRESSION AND TELOMERE LENGTH IN XIPHOPHORUS

Research focusing on telomere length and telomerase expression has become increasingly important due to the association of these two biological endpoints with cellular aging and cancer. However, in vivo studies examining telomeres and telomerase are limited to only a few vertebrate models. Currently, research relies upon the traditional use of laboratory mice strains that have telomeres with extremely long lengths and high variability. More recently, fish species have been shown to provide a potentially informative model for examining the role of telomeres and telomerase within intact animals. As a current model for melanoma research and a new world live‐bearing genus, Xiphophorus had not previously been assessed for telomere length. To add to the knowledge base of telomere and telomerase biology we have begun to assess telomere length and telomerase expression among several species of Xiphophorus . The telomere lengths of select organs (Gill, Brain, Eyes, and Liver) were measured in three species ( X. helleri , X. maculatus , X. couchianus ) and also in F 1 interspecies hybrids made by crossing these parental species. Telomere sizes were consistent within the same organs of the same species, as well as between species, with an average length of approximately 3kb. Although the average telomere lengths found in Xiphophorus are much smaller in comparison to humans, the consistency of sizes would allow for detection of telomere shortening. In addition to studying telomere length in Xiphophorus , sequence data from the catalytically active portion of telomerase, telomerase reverse transcriptase (TERT), was examined and various transcription levels observed. We are currently profiling TERT expression in Xiphophorus by quantitative real‐time PCR analysis as well fluorescent microscopy in order to develop a model that would allow accurate quantification of telomerase activity.