PASADENA, Calif.Researchers at the California Institute of Technology (Caltech) and the University of California, San Diego (UCSD) have discovered that injecting a simple hormone into leeches creates a novel way to study how hormones and the nervous system work together to produce species-specific reproductive behavior.
A paper describing the work appears in the March 11 online edition of the journal Current Biology.
Daniel Wagenaar, Broad Senior Research Fellow in Brain Circuitry at Caltech and first author of the paper, found that injecting a particular hormone into a medicinal leech (Hirudo verbana) induced a series of movements that closely mimic natural reproductive behavior, including a stereotypical 180-degree twisting of the body. Wagenaar's studies were initiated at UCSD.
The twisting, which occurs with a period of approximately five minutesmaking it one of the slowest behavioral rhythms ever discovered, aside from diurnal and annual rhythmsserves to align the reproductive pores on the ventral (under) side of one leech with the complementary pores on the ventral side of a partner, thus facilitating copulation. Without this behavior, copulation would fail.
"In many animal species, sexual reproduction involves highly specific and complex behaviors at all stages from courtship to copulation and beyond," Wagenaar says. "Most animals perform these behaviors without any learning, which strongly suggests that the behaviors are somehow 'hardwired' in their nervous systems."
The relationship between the activity of nerve cells and leech behavior has been very well studied, and the simplicity of the leech nervous system, which contains only about 15,000 neuronsorders of magnitude fewer than even a mosquitohas greatly facilitated this work.
The studies described in Wagenaar's paper were inspired by the combination of the complex behaviors of leeches breeding in the laboratory and its relatively simple
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| Contact: Kathy Svitil ksvitil@caltech.edu 626-395-8022 California Institute of Technology Source:Eurekalert |