Biologists observe a molecular 'hand-off' that plays a key role in reproduction

Sperm is made exclusively by males. Females contribute to what makes a sperm a sperm.

According to the Centers for Disease Control and Prevention, nearly 20% of couples in the United States fail to conceive naturally after one year of trying. In species with internal fertilization, the ability for a female to become pregnant and carry a baby to term is dependent on the interaction between sperm and the female reproductive tract. The result can be a failed pregnancy if the interactions are not good. Understanding the factors that contribute to sperm viability between copulation and fertilization is important.

Steve Dorus, associate professor of biology at Syracuse University, is leading a research team that is studying the life history of fruit fly sperm. Their results were published in the journal PNAS on March 7, 2022, and shed light on important events that may play a role in infertility that up until now have been poorly understood.

The team, which includes members from Syracuse University's Center for Reproductive Evolution, explored the changes in fruit fly sperm after they leave the testis, following insemination and finally after lengthy storage within the FRT. Fruit flies are easy to culture in the laboratory, have a short generation time, and their genetics are well understood, making them a powerful model organisms for investigations. The group discovered that the proteome of the sperm undergoes significant changes after being transferred to the FRT.

It takes a sperm on its way to its final destination of an egg and beginning a new life to destroy both male and female reproductive tracts. Sperm travel through the male's seminal vesicles and descend through the ejaculatory duct after leaving the testis. The team found that many seminal proteins are lost after sperm migrate beyond the site of insemination within the FRT.

The sperm begin to associate with the female-derived female-derived female-derived female-derived female-derived female-derived male-derived male-derived male-derived male-derived male-derived male-derived male-derived male-derived male-derived male-derived male-derived The research team was surprised to find out that 20% of the sperm's proteins had been replaced by female-derived proteins. During the period between copulation and fertilization, the female contributions support sperm viability. The maintenance of sperm viability from males to females means that sperm are the product of both sexes, and this may be a crucial aspect of reproduction in all internally-fertilizing species, including humans.

By studying the intimate ways in which sperm interact with the FRT during the final stages of functional maturation, the team's research advances understanding of animal fertility and the contributions of each sex to reproductive success.

More information: Erin L. McCullough et al, The life history of Drosophila sperm involves molecular continuity between male and female reproductive tracts, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2119899119 Journal information: Proceedings of the National Academy of Sciences Citation: Biologists observe a molecular 'hand-off' that plays a key role in reproduction (2022, March 8) retrieved 8 March 2022 from https://phys.org/news/2022-03-biologists-molecular-hand-off-key-role.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.