{"id":324889,"date":"2026-03-11T22:33:11","date_gmt":"2026-03-11T22:33:11","guid":{"rendered":"https:\/\/www.newsbeep.com\/nz\/324889\/"},"modified":"2026-03-11T22:33:11","modified_gmt":"2026-03-11T22:33:11","slug":"selfish-sperm-hijack-genetic-gatekeeper-to-kill-healthy-rivals-theu","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/nz\/324889\/","title":{"rendered":"Selfish sperm hijack genetic gatekeeper to kill healthy rivals \u2013 @theU"},"content":{"rendered":"

A new University of Utah-led study<\/a> has discovered the mechanism behind a decades-old evolutionary mystery\u2014how \u201cselfish chromosomes\u201d cheat the rules of genetic inheritance. The researchers found that rogue chromosomes hijack the Overdrive (Ovd) gene to destroy rival sperm.<\/p>\n

The study is the first to identify that the Ovd gene acts as a quality control checkpoint during sperm development. Normally, Ovd detects and eliminates abnormal sperm cells. But selfish chromosomes exploit the system to kill competitors, boosting their chances of passing into the next generation.<\/p>\n

The findings reveal the biology behind segregation distortion, a phenomenon in which genes sway inheritance in their favor to beat the standard 50\/50 odds predicted by Mendelian genetics. The team observed the scheme in two Drosophila species, each carrying completely different selfish chromosomes, which suggests that multiple genetic systems may evolve independently to exploit the same Ovd pathway.<\/p>\n

\"Three<\/a>From left to right, coauthors Jackson Ridges, Nitin Phadnis and Jackson Bladen reviewing an image of a heat-stressed Drosophila seminal vesicle (the sperm storage organ). Credit: Phil Baldassari<\/p>\n

\u201cThis is the first time that the same gene has been shown to be crucial for eliminating gametes by multiple independent selfish chromosomes,\u201d said Jackson Ridges, U biologist and lead author of the study. \u201cIt indicates that evolutionarily distant selfish chromosomes may often converge on shared cellular processes.\u201d<\/p>\n

Scientists first discovered segregation distortion in the 1920s while studying the fruit fly Drosophila obscura. Since then, the phenomenon has been found across the animal kingdom, from nematodes to mammals, yet its underlying mechanisms have remained unknown.<\/p>\n

While humans lack an exact genetic equivalent, a similar quality-control process may exist that uses different machinery. The findings could offer new insights into male infertility and the evolution of reproductive barriers between species.<\/p>\n

\u201cHow selfish genes can cause sterility has been a long-standing mystery in field of speciation,\u201d said Nitin Phadnis<\/a>, associate professor at the U and senior author of the study. \u201cBy going for a deep understanding of how Overdrive works, we inadvertently opened up entirely new directions of research into understanding the mechanisms of cellular quality control systems, and how sterility emerges between young species.\u201d<\/p>\n

The version of record of the study was published on Feb. 10, 2026, in the journal Nature Communications<\/a>.<\/p>\n

Selfish chromosomes and the Overdrive gene
\n\"An<\/a>An image of a Drosophila pseudoobscura testis. The DNA of developing spermatids was stained and digitally tinted for depth. Credit: Christopher Large<\/p>\n

Nearly 20 years ago, then grad student Phadnis and mentor H. Allen Orr first identified Ovd as an element in male sterility and segregation distortion in hybrids between two Drosophila species. Their 2009 paper<\/a> revealed that the gene could block competing sperm from forming. The findings led to widespread acceptance that segregation distorters can drive reproductive isolation between species. He explored other topics as a post doc, but Ovd never left his mind.<\/p>\n

\u201cA big question in evolutionary genetics is, \u2018What is the engine that drives genes to evolve such that organisms diverge into new species\u2014internal genetic conflict or organismal adaptation? Our Overdrive discovery was the first clear, direct link between the two phenomena,\u201d Phadnis said. \u201cWhen I started my own lab, it was time to pick it back up, but this time we wanted to get at how it actually works.\u201d<\/p>\n

First, the researchers tackled whether Ovd was essential to sperm production. Jackson Ridges, doctoral student in the Phadnis lab, led the experiments.<\/p>\n

\u201cI wanted to look for a way that we can show this isn\u2019t just some weird selfish chromosome stuff going on. This is a genuine physiological phenomenon that we\u2019re investigating,\u201d Ridges said.<\/p>\n

The group knocked out the Ovd gene in D. pseudoobscura and D. melanogaster to test two different, completely independent selfish chromosomes. Surprisingly, they observed no difference in male fertility, establishing that the gene isn\u2019t necessary for sperm production in either species.<\/p>\n

\"A<\/a>Coauthor Jackson Bladen sorting anesthetized Drosophila. Credit: Phil Baldassari<\/p>\n

\u201cThis got us thinking, \u2018What other genes work like this?\u2019\u201d Ridges said. The P53 gene\u2019s role in cancer came to mind. P53 works as a safeguard to stop runaway cell reproduction. Flies without P53 are fine unless there\u2019s a problem to genome integrity.<\/p>\n

\u201cMaybe Ovd\u2019s only role is to recognize damage and remove those cells. But if there\u2019s no damage, everything\u2019s fine without it,\u201d Ridges said. \u201cIt was the primary way we could connect all these findings that didn\u2019t make intuitive sense, at first.\u201d<\/p>\n

To test their theory, they used a well-known temperature threshold beyond which fruit flies can\u2019t reproduce. At temperatures greater than 31\u00ba C, all male Drosophila go sterile, but no one knew why.<\/p>\n

After exposing normal flies and flies without Ovd to a high-temperature bacterial incubator for one week, the normal fly stock was sterile while the males without Ovd produced progeny. Ovd was blocking sperm formation at the high temperature to prevent potential unhealthy sperm.<\/p>\n

\u201cThat was the final nail in the coffin\u2014Overdrive\u2019s normal function is acting as a blocker of bad gametes. When you remove the blocker, then the selfish behavior goes away,\u201d Phadnis said. \u201cThat doesn\u2019t mean Overdrive is the selfish gene\u2014it\u2019s just being hijacked.\u201d<\/p>\n

The team\u2019s next steps are to knock out Overdrive in different Drosophila species to assess how many other selfish chromosomes in different species operate through this system of hijacking the Overdrive checkpoint. They\u2019re also investigating if segregation distortion occurs in human lineages.<\/p>\n

*****<\/p>\n

Other authors include Jackson Bladen, Thomas King, Nora Brown, Christopher Large, Jacob Cooper and Amanda Jones from the University of Utah; and Benjamin Loppin and Rapha\u00eblle Dubruille from the Universit\u00e9 Claude Bernard.<\/p>\n

This work was supported by the National Institute of Health (R01GM141422 and R35GM156267) and the French National Research Agency (ANR-21-CE13-0037).<\/p>\n

Study citation:<\/p>\n

Ridges, J.T., et al.\u00a0Selfish chromosomes exploit a germline checkpoint to eliminate competing gametes.\u00a0Nat Commun\u00a017, 1532 (2026). https:\/\/doi.org\/10.1038\/s41467-025-68254-7<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"A new University of Utah-led study has discovered the mechanism behind a decades-old evolutionary mystery\u2014how \u201cselfish chromosomes\u201d cheat…\n","protected":false},"author":2,"featured_media":324890,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[111,139,69,147,175260,9320,9318,9319],"class_list":{"0":"post-324889","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-new-zealand","9":"tag-newzealand","10":"tag-nz","11":"tag-science","12":"tag-selfish-sperm-hijack-genetic-gatekeeper-to-kill-healthy-rivals-theu","13":"tag-the-u","14":"tag-the-university-of-utah","15":"tag-uofu"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/324889","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/comments?post=324889"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/posts\/324889\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media\/324890"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/media?parent=324889"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/categories?post=324889"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/nz\/wp-json\/wp\/v2\/tags?post=324889"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}