The Role of Histone Variants in Sperm Formation in C. elegans

Male infertility has been a continuing enigma contributing to the inability to reproduce. To further our understanding of fertility factors required for healthy sperm formation, we studied the role of proteins, called histones and histone variants, in packaging sperm DNA in the model organism C. elegans. During sperm formation, histones tightly package large amounts of DNA forming chromosomes. Our experiments focused on two histone variants, HTAS-1 and HIS-35. Previous research indicated the H2A variant, HTAS-1, is a sperm-specific fertility factor. Our first aim was to visualize the link between HTAS-1 in chromosome compaction and transcription during sperm formation by fluorescence microscopy. We used immunostaining to visualize both HTAS-1 and RNA Polymerase II, an enzyme known to catalyze the transcription of DNA. From our data, we concluded HTAS-1 was present in the proximal end of the germ line while RNA Pol II was present on the distal end. This indicates HTAS-1 may not play a major role in regulating transcription activation. Our second aim was to create a mutant strain that generates male progeny to investigate the role of another histone H2A variant, HIS-35, in male infertility. I successfully conducted a series of genetic crosses followed by Polymerase Chain Reaction and gel electrophoresis to construct a strain mutated for HIS-35. This new strain allows us to conduct future experiments investigating when HIS-35 is expressed in the male germ line and the role of HIS-35 in sperm formation.