Scientist scours globe for largest freshwater fish
PHNOM PENH, Cambodia -- American biologist Zeb Hogan is on the ultimate fisherman's quest: to find and save the world's largest freshwater fishes.\nHis search is to take him to 10 rivers around the globe including the Nile, Amazon and Mississippi, looking for about 20 species of hulking fish such as the goliath catfish, Chinese paddlefish and North American lake sturgeon.\nRight now Hogan is on the Mekong, looking for a stingray said to weigh over 1,300 pounds -- as much as a full-grown longhorn steer.\nHogan expects to finish in December 2006 and give his fish counts to IUCN, the World Conservation Union, which compiles a Red List of Threatened Species.
IUCN lists some of the giants as endangered or critically endangered, but for others, there simply isn't enough data to judge.
NEW YORK -- The human Y chromosome -- the DNA chunk that makes a man a man -- has lost so many genes over evolutionary time that some scientists have suspected it might disappear in 10 million years. But a new study published in the journal Nature said it'll stick around.\nResearchers found no sign of gene loss over the past 6 million years, suggesting the chromosome is "doing a pretty good job of maintaining itself," said researcher David Page of the Whitehead Institute for Biomedical Research in Cambridge, Mass.\nThe Y appeared 300 million years ago and has since eroded into a dinky chromosome, because it lacks the mechanism other chromosomes have to get rid of damaged DNA. So mutations have disabled hundreds of its original genes, causing them to be shed as useless. The Y now contains only 27 genes or families of virtually identical genes.
