2023 38 B2

Exploring Epigenetic Inheritance of HIS-35 and HTAS-1 and their Role in Transcriptional Regulation

By: Keiko Hokeness, Emma Harms

Department: Biology

Faculty Advisor: Dr. Diana Chu

Nucleosomes regulate the accessibility of the genes to transcription factors, including RNA polymerase II. The four histone proteins within the nucleosome can undergo replacement resulting in an altered pattern of gene expression. In the model organism, C. elegans, two variants of histone H2A (HTAS-1 and HTZ-1) seem to impact C. elegans’ fertility as they regulate genes involved in the production of oocytes and sperm. There is little published data regarding the third variant: HIS-35. The inheritance of histone variants is vital for providing new embryos with epigenetic information, crucial for proper gene regulation of gamete-specific processes. The fate of maternal and paternal HIS-35 and HTAS-1 in newly fertilized embryos remains unknown along with the understanding of HIS-35’s role in regulating transcription. Using a mixed-method approach, we will determine the extent to which HIS-35 is involved in the transcriptional regulation of gametogenesis-specific genes. We prepared whole worm and germline samples of the mutant C. elegans strain with the his-35 deletion for RNA sequencing and identified differentially expressed genes. We expect to find significant differences in expression levels as supported by preliminary data showing a reduction in progeny due to incomplete fertility. Additionally, we aim to understand the effects of maternal vs paternal deposition of HIS-35 and HTAS-1 through progeny observation of strategic crosses that isolate the effects of the mutations in specific expression circumstances. Immunostaining and confocal microscopy will allow us to track variants in maternal and paternal genomes within the embryo to supplement our findings. Limited preliminary data shows paternal HIS-35 absence following fertilization which we aim to further investigate. Accumulating knowledge of HIS-35’s role in regulating sex-specific processes will expand the existing information surrounding this H2A variant. Understanding the behavior of paternal and maternal HIS-35 and HTAS-1 will elucidate their roles in depositing epigenetic information in the new embryo.