Fish cancer gene linked to pigment pattern

Athens, Ohio -- U.S. biologists have discovered black skin cancer spots found on some fish also serve as natural markings that lure female mates.

Ohio University scientists Andre Fernandez and Molly Morris studied female swordtails -- tiny freshwater fish native to North and Central America -- and found two of them preferred males whose tails were painted to resemble the skin cancer spots.

The researchers also examined specimens of swordtail fish with real melanomas, confirming the cancer gene is switched on only in the tissue with the dark pigment.

Fernandez and Morris said their study marks the first time scientists have found a cancer gene linked to a pigment pattern that functions to increase mating success in animals.

Swordtail fish usually live for 1.5 to 2 years in the wild and sexually mature at 4.5 months. The ones with the skin cancer gene can develop melanomas at about 7 months and die a few months later.

"Melanoma formation cuts the reproductive life cycle in half," Fernandez said.

"It has a huge cost for males." But Fernandez noted that during the few months when the male is sexually mature and healthy, he also can produce a lot of offspring.

The study appears in the Proceedings of the National Academy of Sciences.

Copyright 2008 by United Press International.