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Title: BOMBYXIN STIMULATES PROLIFERATION OF CULTURED STEM CELLS DERIVED FROM HELIOTHIS VIRESCENS AND MAMESTRA BRASSICAE LARVAE

Author
item GOTO, S. - KOBE UNIVERSITY
item Loeb, Marcia
item TAKEDA, M. - KOBE UNIVERSITY

Submitted to: In Vitro Cellular and Developmental Biology - Animal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/15/2004
Publication Date: 1/15/2005
Citation: Goto, S., Loeb, M.J., Takeda, M. 2005. Bombyxin stimulates proliferation of cultured stem cells derived from heliothis virescens and mamestra brassicae larvae. In Vitro Cellular and Developmental Biology - Animals. 40:38-42

Interpretive Summary: Caterpillars spend most of their time eating. Since all that they ingest, including leaves, pesticides, poisons and viruses, enter the midgut, it is important to understand how growth and repair of this large organ is controlled. Growth and repair are based on multiplication and maturation of midgut stem cells. In this work, we examined various peptides similar to the hormone, insulin, that causes the cells of the midgut to multiply. Bombyxin is the insect version of insulin, and regulates sugar metabolism and some growth and development functions in insects. We discovered that bombyxin and other commercially available insulin-like growth factors induce stem cells of the insect midgut to multiply in vitro. However, these factors act quickly and become inactivated quickly, similar to the effects of insulin on mammalian tissues. When all of the factors that can cause midgut cells to multiply are known, it may be possible develop better means to control pest Lepidoptera by inhibiting the multiplication of their stem cells. This capability will be particularly important in preventing the repair of midgut tissue after exposure to pesticides, enhancing the effects of the pesticides by allowing use of reduced amounts of pesticides in the field. This work can only be used by scientists at this point.

Technical Abstract: Insulin, IGF-1, IGF-2 and bombyxin stimulated proliferation in vitro of midgut stem cells derived from two noctuiid larvae, Heliothis virescens and Mamestra brassicae in vitro. Bombyxin induced a maximum effect at 10-12M. The number of cells was greatest 3 days after the addition of bombyxin. Although a single dose of bombyxin could not maintain proliferation, a second dose administered 3 days after the first treatment retained the effect. Results suggest that the decline of effect after the first addition was not due to the loss of sensitivity of the cultured cells but to the loss of effect in the growth factor added. Increased doses of bombyxin showed a suppression of the activity. Bombyxin was not the growth factor contained in the fat body extract (FBX) from developing pupae of Manduca sexta, since the addition of FBX to the culture medium containing the concentration of bombyxin that induced an intermediate degree of cell proliferation effect, i. e., at 10-10M, did not further increase the proliferation activity. Additivity was not observed. The results lead to the conclusion that the bombyxin is a unique growth factor that stimulates proliferation in vitro at least of midgut stem cells from lepidopteran larvae.