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

Date:
March 8, 2022
Source:
Syracuse University
Summary:
Novel research on the life history of fruit fly sperm demonstrates
molecular continuity between the male and female reproductive
tracts.



FULL STORY ========================================================================== Nearly 20 percent of couples in the United States fail to conceive
naturally after one year of trying, according to the Centers for Disease Control and Prevention. In species with internal fertilization, such as
humans, the ability for a female to become pregnant and carry a pregnancy
to term is dependent upon effective interactions between sperm and the
female reproductive tract (FRT).

When those interactions are defective, the result can be a failed
pregnancy.

Therefore, understanding the factors that contribute to sperm viability
between copulation and fertilization is crucial.


==========================================================================
A research team from the Syracuse University College of Arts and
Sciences' Department of Biology and Cornell University, led by Steve
Dorus, associate professor of biology at Syracuse University, have
been studying the life history of fruit fly (Drosophila melanogaster)
sperm to better understand molecular continuity between male and
female reproductive tracts. In other words, how the male and female reproductive tracts provide support to keep the sperm viable before fertilization. Their results, published on March 7, 2022 in the journal Proceedings of the National Academy of Sciences USA (PNAS), 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 compositional changes in fruit
fly sperm, beginning shortly after they leave the testis, following insemination and finally after protracted storage within the FRT. Fruit
flies are powerful model organisms for investigations such as this
one because they are easy to culture in the laboratory, have a short
generation time and their genetics are richly understood. In their study,
the group uncovered that the proteome, or protein makeup, of the sperm undergoes substantial changes after being transferred to the FRT.

For species with internal fertilization, a sperm's developmental
'journey' - - on the way to its final destination of fertilizing an egg
and beginning a new life -- transcends both male and female reproductive tracts. After leaving the testis, sperm travel through the male's seminal vesicles and descend through the ejaculatory duct, where they mix with
seminal fluid proteins. The team found that many of these seminal proteins
are progressively lost after sperm migrate beyond the site of insemination within the FRT. Conversely, female- derived proteins that may help the
sperm with functions such as energy metabolism, begin to associate with
the sperm immediately after mating, signifying a changing of the guard
of proteins. After several days of storage within the FRT, the research
team was surprised to discover that nearly 20% of the sperm's proteins
had been replaced by female-derived proteins. The female contributions
support sperm viability during the prolonged period between copulation
and fertilization. This "hand-off" in the maintenance of sperm viability
from males to females means that sperm are materially 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.

In addition to Dorus and Pitnick, other co-authors from Syracuse
University included former postdoctoral researcher Erin McCullough and
doctoral graduate Emma Whittington. Co-authors from Cornell University
were Professor Mariana Wolfner and postdoctoral researcher Akanksha
Singh. The team's research was funded by the National Science Foundation,
the National Institutes of Health and a gift from Mike and Jane Weeden
to Syracuse University.


========================================================================== Story Source: Materials provided by Syracuse_University. Original written
by Dan Bernardi.

Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Erin L. McCullough, Emma Whittington, Akanksha Singh, Scott Pitnick,
Mariana F. Wolfner, Steve Dorus. The life history of Drosophila
sperm involves molecular continuity between male and female
reproductive tracts. Proceedings of the National Academy of
Sciences, 2022; 119 (11) DOI: 10.1073/pnas.2119899119 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220308102840.htm

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