Effects of peptide hormones on feeding initiation and termination in the larvae of the silkworm, Bombyx mori
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1
The University of Tokyo, Department of Applied Biological Chemistry, Japan
Phytophagous insects do not always feed, even though they reside on their host plants. In the larvae of the silkworm, Bombyx mori, the regularly occurring feeding pattern is observed. It has been proposed that such feeding cycles were modulated by the sequential effects by positively and negatively regulating factors including peptidyl factors.
To elucidate the mechanisms of regulation of feeding behavioral cycle, especially that of feeding motivation, we established a bioassay for the activity of feeding initiation by observing the first bite after sample injection in starved Bombyx larvae. The biological activity was evaluated by measuring the duration until the first bite. To test the several biologically active peptides on feeding behavior, we synthesized chemically those peptides including neuropeptide hormones, which were then subjected to the feeding motivation bioassay. As a result, injection of synthetic allatostatin and myosupressin into starved Bombyx larvae delayed the first bite significantly compared with the vehicle-injected larvae, indicating that these peptides are candidates for feeding terminating factors. By contrast, injection of short neuropeptide F (sNPF) into starved larvae resulted in the significantly shortened duration to the first bite, indicating that sNPF might be a candidate for a feeding initiating factor. These results suggest that a number of peptidyl factors are involved in the regulation of insect feeding behaviors. To understand the scenarios of the regulatory order by peptidyl factors, further studies on quantification of those peptides during the feeding cycle are required.
Keywords:
comparative endocrinology
Conference:
25th Conference of the European Comparative Endocrinologists, Pécs, Hungary, 31 Aug - 4 Sep, 2010.
Presentation Type:
Conference Presentation
Topic:
Comparative endocrinology
Citation:
Nagata
S,
Matsumoto
S,
Morooka
N,
Kawai
T and
Nagasawa
H
(2010). Effects of peptide hormones on feeding initiation and termination in the larvae of the silkworm, Bombyx mori.
Front. Endocrinol.
Conference Abstract:
25th Conference of the European Comparative Endocrinologists.
doi: 10.3389/conf.fendo.2010.01.00053
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Received:
26 Aug 2010;
Published Online:
29 Aug 2010.
*
Correspondence:
Dr. Shinji Nagata, The University of Tokyo, Department of Applied Biological Chemistry, Tokyo, Japan, shinjin@edu.k.u-tokyo.ac.jp