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Title: EFFECTS OF INSECT HORMONE ACTIONS, 20E AND JH, ON MIDGUT STEM CELLS OF LEPIDOPTERA

Author
item SMAGGHE, G - FREE UNIV BRUS BELG
item VAN HASSEL, W - FREE UNIV BRUS BELG
item MOERMANS, C - FREE UNIV BRUS BELG
item Loeb, Marcia

Submitted to: In Vitro Cellular And Developmental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/5/2003
Publication Date: 6/1/2003
Citation: Smagghe, G., Van Hassel, W., Moermans, C., Loeb, M.J. 2003. Effects of insect hormone actions, 20e and jh, on midgut stem cells of lepidoptera. In Vitro Cellular And Developmental Biology.

Interpretive Summary:

Technical Abstract: Addition of the two principal insect hormones, 20-hydroxyecdysone (20E) and juvenile hormone (JH3) to the medium containing midgut stem cells cultured in vitro, induced stimulation of stem cell proliferation in a concentration-dependent manner. Stem cells were obtained from larvae of an economically-important pest insect, the cotton leafworm (Spodoptera littoralis; Lepidoptera: Noctuidae). We also tested two metabolically-stable insect growth regulatory compounds, an ecdysteroid agonist, RH-2485, and a juvenile hormone analogue pyriproxyfen. In addition, we compared the in vitro effects with an aqueous extract from the pupal fat body of the tobacco hornworm (Manduca sexta) pupae (FBX), and two purified peptide factors, multiplication protein (MP) isolated from fat body and MDF1 known to induce cell differentiation. Further, with whole insect larvae, we evaluated the effects of RH-2485 and pyriproxyfen on midgut physiology, and on larval growth and development. Typically, RH-2485 induced premature molting and finally larval death, and pyriproxyfen provoked a supernumenary larval stage. From this study, we can report that the dramatic symptoms of midgut hyperplasia with RH-2485 concurs with the high increase in stem cell number observed with 20E and RH-2485 in vitro. Surprisingly, similar effects were observed with FBX. We will discuss the action of the insect hormones, growth factors and the interrelationship with other factors in the development and metamorphosis of the insect midgut.