Tuesday, November 21, 2006
Chilies And Spiders Share Similar Scare Tactics
San Francisco (USA), 20 November: Researchers have identified 3 molecules in tarantula venom that help make the spider’s bite so painful. The peptides activate the same receptor as the hot component of chili peppers, suggesting that tarantulas and chili plants use similar scare tactics to help ward off predators.
Much is known of the specific spider toxins that cause shock, paralysis and death, but the molecules that promote pain and inflammation are less well characterized. In this week’s Nature, David Julius and colleagues describe three peptides, isolated from the venom of the West Indian tarantula Psalmopoeus cambridgei, that bind to and activate a particular receptor on sensory neurons to cause pain. When the newly discovered peptides are injected directly into the hind paw of a mouse, inflammation can be seen and the mice act as if in pain, but only if they have the receptor.
The receptor, which allows ions to pass across the membrane of the cell, is also activated by capsaicin, the active component of chili peppers. So the study suggests that P. cambridgei and chili plants use similar signaling mechanisms to cause pain and scare predators away.
The newly discovered peptides are also unusual because they trigger an excitatory response. Peptides with similar structures that bind to other ion channels are already known, but cause inhibitory responses.
(ResearchSEA)
Much is known of the specific spider toxins that cause shock, paralysis and death, but the molecules that promote pain and inflammation are less well characterized. In this week’s Nature, David Julius and colleagues describe three peptides, isolated from the venom of the West Indian tarantula Psalmopoeus cambridgei, that bind to and activate a particular receptor on sensory neurons to cause pain. When the newly discovered peptides are injected directly into the hind paw of a mouse, inflammation can be seen and the mice act as if in pain, but only if they have the receptor.
The receptor, which allows ions to pass across the membrane of the cell, is also activated by capsaicin, the active component of chili peppers. So the study suggests that P. cambridgei and chili plants use similar signaling mechanisms to cause pain and scare predators away.
The newly discovered peptides are also unusual because they trigger an excitatory response. Peptides with similar structures that bind to other ion channels are already known, but cause inhibitory responses.
(ResearchSEA)
# posted by mediabhartiwebsolutions @ 4:52 AM 
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