Epigenetics is a mechanism for regulating gene expression, and Professor Upasna Sharma at the University of California, Santa Cruz defines epigenetic inheritance as the inheritance of phenotypic changes in the absence of changes in the underlying DNA.

She explains her research by exploring the following:

• The three primary ways in which gene regulation can take place
• What function small non-coding RNA play in epigenetic gene regulation and intergenerational inheritance, and how their location in the cell is dependent upon their function within the cell
• In what ways RNA is more complex than DNA
• What impact stress, environmental toxins, and diet might play in sperm small RNA and transfer RNA

Dr. Sharma is studying the role of small non-coding RNAs in epigenetic inheritance by examining RNA in sperm. How is the environment being signaled to these small RNAs? When do tRNA fragments become abundant in sperm?

Through the research she and her team have already done, they've found that testicular sperm or germ cells do not have tRNA fragments, but as sperm enters the epididymis, it acquires a high abundance of tRNA fragments. Based on the data they've gathered, Dr. Sharma is confident in saying that tRNA fragments are created in the epididymis and then shipped to sperm. Why is this the case?

Dr. Sharma explores possible answers to this question. She also discusses how the female reproductive tract secretes extracellular vesicles and how sperm might be further altered by the female reproductive tract. The overarching aim of her research is to determine how sperm small RNA are generated, how the environment can influence their levels, and what the functional consequence is of the abundant small RNA payload of sperm, as this might help elucidate how epigenetic information is intergenerationally transferred by small RNAs.

Press play for the full conversation.