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PROTAMINE PROMOTER PROVIDES VITAL CELL MARKER FOR EARLY ELONGATING SPERMATIDS IN TRANSGENIC MICE.
Silversides, David1, Daneau, Isabelle1, Dornan, Saffron2, Raiwet, Diana1, 1 2
ABSTRACT- Protamines are small positively charged DNA binding proteins involved in the compact packaging of DNA within the sperm head, where they function to replace histone proteins during spermatid maturation. To facilitate cell fractionation studies during this time of spermatogenesis, we have generated a line of transgenic mice that express yellow fluorescent protein (YFP) under the control of the mouse protamine promoter. Additionally, YFP was designed to include nuclear localization signals (nls), such that the fluorescent signal is directed to the nucleus of expressing cells. BSA cell fractionation and direct FACS sorting of dissagregated testicular cells showed that fluorescence was restricted to the elongating spermatid cell population, and was not retained in released spermatozoa. In adult testes whole mounts, fluorescence was identified within a subpopulation of seminiferous tubules, marking those tubules containing spermatids at the elongating stage of spermatogenesis. Physically this stage could extend for a variable distance up to and including 1 cm in tubule length. This in vivo model of protamine gene expression will be useful for tissue culture, cell fractionation and gene expression studies of spermatogenesis.
KEY WORDS: protamine promoter, yellow fluorescent protein, elongating spermatids, transgenic mouse