Male Pregnancy

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Gene “archaeology” sheds light on male pregnancy A bit of “ge­netic ar­chae­o­lo­gy” may be il­lu­mi­nat­ing one of the fish world’s great mys­ter­ies, re­search­ers say: how did a fam­i­ly of fish come to em­brace male preg­nan­cy? The sea­horse Hip­po­cam­pus erec­tus (cour­te­sy NOAA) Research in the gulf pipe­fish hints that a gene orig­i­nal­ly busy with kid­ney and liv­er func­tions may have learn­ed new ones in the male womb, said April Har­lin-Cog­nato, a zo­ol­o­gist at Mich­i­gan State Uni­ver­si­ty in East Lan­s­ing, Mich. “We’re in­ter­est­ed in the ev­o­lu­tion of nov­el­ty,” Har­lin-Cog­nato said. “We’re won­der­ing if it’s a mat­ter of old genes gain­ing new tricks.” Gulf pipe­fish are a mem­ber of the same fam­i­ly as sea­horses, which they in fact re­sem­ble, ex­cept for the curved tails. As with sea­horses, the male fish ac­cepts eggs from fema­les, fer­til­izes them and car­ries them in a pouch, a com­plex or­gan that nur­tures and pro­tects the eggs. One of its func­tions is to reg­u­late sa­line con­tent in the womb, ac­cord­ing to Har­lin-Cog­nato. She and col­leagues found a new gene that makes a type of pro­tein mol­e­cule called an astac­in—one a fam­i­ly of pro­teins found in bony fish. The gene, which the re­search­ers dubbed pa­tristacin, ap­pears to sup­port the pouch, but this was­n’t its orig­i­nal job, she ar­gues. Mem­bers of her team sus­pect that pa­tristacin, pos­si­bly thou­sands of years ago, was in­volved in kid­ney and liv­er func­tion, and was lat­er drafted in­to a “moon­light­ing” gig sup­porting the then-newfangled male brood pouch. Pa­tristacin is found in the brood pouch of pipe­fish and sea­horses and in the kid­ney and liv­er of bony fish. “We know the gene codes for a pro­tein in the brood pouch dur­ing male preg­nan­cy, but we don’t know yet what it is do­ing in the brood pouch. It’s a whole new ball of wax to un­der­stand how this gene func­tions in its new job,” Harlin-Cog­nato said. The team’s study ap­pears in the Nov. 4 edi­tion of the re­search jour­nal Pro­ceed­ings of the Na­tion­al Acad­e­my of Sci­ences. “The genes show you an­ces­try,” she said. “They show you the over­all fam­i­ly tree and can tell you when things took place dur­ing the ev­o­lu­tion of a new struc­ture. From this fam­i­ly tree we can make ed­u­cat­ed guesses about the struc­ture and func­tion of these pro­teins.”