This week in animal research: w/e 12 December
Size matters, well in the case of zebra finch sperm it does. Zebra finch males with longer sperm fertilize more eggs, and farther more chicks, than males with shorter sperm. In the study, they sired 64% of the embryos, even if the shorter sperm males had a head start. The longer sperm probably swim faster, end up in more of the female’s sperm storage spots for later use and are better at staying there.
“Our findings are important because they demonstrate for the first time in birds, using a controlled competitive scenario, that sperm length can influence the fertilization success of a particular male. The results also add to the body of evidence suggesting that the final outcome of sperm competition may be partly dependent on the female, and that the chance of a male siring offspring may not be an outcome of a simple ‘race to the egg,'" says Dr. Clair Bennison from the University’s Department of Animal and Plant Sciences.
New research shows that coral-dwelling filefish camouflage themselves by not only looking, but also smelling like their prey. This little orange spotted fish feeds exclusively on Acropora coral in Australia, and by doing so ingests chemicals in the coral that makes it smell like its food. This helps the fish hide away from its own predators. This is the first evidence of an animal using chemical camouflaging via its diet but it is probably more common than imagined.
"Most of the literature on camouflage focuses on visual methods, but many animals use smell more. For these animals, chemical camouflage may be far more important to stay hidden," said Rohan Brooker, currently a postdoctoral student at the Georgia Institute of Technology in Atlanta.
Photo: jaredzimmerman , via Wikimedia Commons
Researchers have found genetic evidence that highly toxic venom proteins actually come from non-toxic genes that have duplicated, migrated and evolved to the oral glands. These non-toxic genes have functional roles in the body such as regulation of cellular function or food digestion. A snake species gets a venomous label if its oral glands express some of the 20 genes families associated with venom. However, because of their evolutionary origin, these genes can be found in various places in the body which challenges the previous labelling system.
"Research on venom is widespread because of its obvious importance to treating and understanding snakebite, as well as the potential of venoms to be used as drugs, but, up until now, everything was focused in the venom gland, where venom is produced before it is injected," Todd Castoe, lead researcher said. "There was no examination of what's happening in other parts of the snake's body. This is the first study to have used the genome to look at the rest of that picture."
These results demonstrate that genes or transcripts which were previously interpreted as 'toxin genes' are instead most likely housekeeping genes, involved in the more mundane maintenance of normal metabolism of many tissues," said Stephen Mackessy, a co-author on the study and biology professor at the University of Northern Colorado. "Our results also suggest that instead of a single ancient origin, venom and venom-delivery systems most likely evolved independently in several distinct lineages of reptiles."
Scientists have partially restored the sight of animals suffering from congenital blindness using gene therapy to replace the lost light-sensitive cells of the eye. Dogs and mice with a condition similar to retinitis pigmentosa regained some of their vision following the therapy, which used a human gene to increase light sensitivity in retinal cells.
“The dog has a retina very similar to ours, much more so than mice, so when you want to bring a visual therapy to the clinic, you want to first show that it works in a large animal model of the disease,” said Professor Isacoff, who led the research team.
New drug eliminates the malaria parasite within 48 hours in mice. Malaria is caused by a parasite that penetrates the body from a mosquito bite and infects and hijacks red blood cells to reproduce. The new compound transforms the infected red blood cells so they show signs of aging, which tricks the immune system into targeting and destroying them, but leaves healthy cells unharmed. It has already been tested in mice and trials are now planned in humans.
"The data suggest that compounds induce physical changes in the infected red blood cells that allow the immune system or erythrocyte quality control mechanisms to recognise and rapidly eliminate infected cells," said co-author Joseph DeRisi in a press release. "This rapid clearance response depends on the presence of both the parasite and the investigational drug. That is important because it leaves uninfected red blood cells, also known as erythrocytes, unharmed. Our goal is to develop an affordable, fast-acting combination therapy that cures malaria with a single dose."
Electric eels can use their electric organs to remotely control their prey. The electric pulses released by the eels during hunting can make all the muscles in their prey twitch, serving to immobilise them or causing them to reveal their whereabouts.
Kenneth Catania, who led the study at Vanderbilt University in Nashville, Tennessee said “You and I couldn't activate every muscle in our bodies at once, but the eels can do that [remotely] in their prey. They can completely immobilise prey or they can make prey move, depending on what they would like to do.”