Findings

Science  15 Jul 2011:
Vol. 333, Issue 6040, pp. 273
  1. Diver Snaps First Photo of Fish Using Tools

    While exploring Australia's Great Barrier Reef, professional diver Scott Gardner snapped the first photographs of a wild fish using a tool. Gardner found a footlong blackspot tuskfish (Choerodon schoenleinii) holding a clam in its mouth and whacking it against a rock. The shell gave way, and the fish gobbled up the bivalve, spat out the shell fragments, and swam off.

    CREDIT: SCOTT GARDNER

    Once thought to be the hallmark of human intelligence, tool use has been observed in a wide variety of animals. To date, however, there has been no photo or video evidence of tool-using fish.

    In fact, tool-using tuskfish might be commonplace, says Culum Brown, a behavioral ecologist at Macquarie University in Sydney, Australia, and a co-author of a paper to be published in Coral Reefs. Numerous middens of crushed shells are visible around the reef.

    Primatologist Elisabetta Visalberghi of the Institute of Cognitive Sciences and Technologies in Rome suggests the tuskfish's behavior is more accurately called proto-tool use, however. A stricter definition of tool use requires the animal to hold or carry the tool itself, in this case the rock, which is cognitively more demanding. http://scim.ag/fishtools

  2. Antiparasitic Drug Has Bonus Effect on Mosquitoes

    Ivermectin, already used to control river blindness and elephantiasis in many African countries, could also drive down malaria, a new study has found. The drug makes mosquitoes less likely to transmit Plasmodium falciparum, the malaria parasite.

    A team led by Brian Foy, a vector biologist at Colorado State University in Fort Collins, has been studying mosquito populations in an area in southeastern Senegal where ivermectin, donated by Merck, is administered annually by the government in a mass drug administration (MDA) to stop river blindness. Previously, the group had shown that this shortened the life span of local Anopheles mosquitoes, which ingest the drug as they suck up the blood of their victims.

    Buzzing.

    One of the test sites in Senegal.

    CREDIT: BRIAN FOY

    In the new study, they found that it also reduces the chances of P. falciparum fully developing inside the insect. The team compared three villages that took part in an MDA and three others nearby that did not. In the treated villages, the proportion of mosquitoes with parasites in their saliva dropped by 79% in 2 weeks; in the others, it rose by 246%, the researchers report in The American Journal of Tropical Medicine and Hygiene.

    More studies are needed, but mass treatment with ivermectin might be a new weapon against malaria, says Foy—although once-a-month distributions may be necessary. Whether Merck would support the needed increase in drug supply is unclear.

    http://scim.ag/_ivermectin

  3. Polar Bears Rooted in Ireland

    Polar bears and brown bears were separate species by 110,000 years ago. But new genetic studies of fossils and modern bears have revealed some hanky-panky 45,000 years ago, when polar bears interbred with now-extinct Irish brown bears.

    Hybridization with brown bears is a concern today because declining sea ice cover is forcing polar bears to extend their range and come into contact with brown bears. To understand the implications of hybridization, Beth Shapiro, an evolutionary biologist at Pennsylvania State University, University Park, and her colleagues compared mitochondrial DNA from 8000-year-old polar bear fossils, modern samples of polar bears, and ancient Irish bear fossils.

    CREDIT: FOTOSEARCH (2)

    Modern polar bear mitochondrial DNA was most similar to that of the extinct Irish brown bear, whereas extinct polar bears had different mitochondria. Thus modern polar bears come from Europe, not islands between Alaska and Siberia, as had been previously thought, the researchers reported in Current Biology.

    The finding shows that interbreeding occurred during past episodes of climate change didn't destroy a species. “The big question for conservation of polar bears is if hybridization occurs rapidly and in combination with other stressors, will that hybridization have more of a negative effect now than it did in the past,” says Andrew Whiteley, a geneticist at the University of Massachusetts, Amherst. http://scim.ag/_polarbears

  4. Language Protein May Help Build Brain Circuits

    A protein in the brain called Foxp2 that has been linked to the development of human language may push developing neurons to reach out and touch other brain cells.

    Scientists identified Foxp2 in 2001 and have since linked it to a number of speech disorders in humans and other animals. Zebra finches with low levels of Foxp2, for example, can't learn the songs that other birds sing. To tease out this talkative protein's role in brain development, researchers screened thousands of genes in embryonic mice brains, looking for those switched on or off by Foxp2. In brain tissue bathed in high concentrations of Foxp2, the protein kicked about 160 genes into gear, the team reported online 7 July in PLoS Genetics.

    While Foxp2 casts a wide net, it also disproportionately oversees genes involved in brain cell organization. Specifically, the protein helps to guide the growth of neuronal neurites, appendages that reach out to other neurons. Such connection-building during development could be critical for learning later in life, laying the foundation for the formation of neural circuits which pass information between brain regions. http://scim.ag/languageprotein

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