Peptides that elicit midgut stem cell differentiation isolated from chymotryptic digests of hemolymph from Lymantria dispar pupae |
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Authors: | Loeb Marcia J Jaffe Howard |
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Affiliation: | Insect Biocontrol Laboratory, U.S. Department of Agriculture, Bldg 011A, Rm 214, BARC West, Beltsville, MD 20705, USA. loebm@ba.ars.usda.gov |
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Abstract: | Isolated stem cells of Heliothis virescens, cultured in vitro, were induced to differentiate by Midgut Differentiation Factors 3 and 4. These were peptides identified from a chymotrypsin digest of hemolymph taken from newly pupated Lymantria dispar. Partial purification was obtained by filtration through size exclusion filters. The most active preparation was subsequently subjected to a series of 3 Reverse Phase-HPLC procedures. Partial sequences of the peptides were identified via automated Edman degradation as the nanomers EEVVKNAIA-OH (MDF 3) and ITPTSSLAT-OH (MDF 4). These sequences were commercially synthesized. The synthetic compounds proved active in a dose-dependent manner. Stem cells responded to synthetic MDF 3 and MDF 4 as they did to previously identified peptides MDF 1 and 2, which have quite different amino acid sequences. All of the 4 MDFs administered singly induced statistically similar differentiation responses at 2 x 10(-8), 2 x 10(-9), and 2 x 10(-10) M. However, pairs of the 4 MDFs produced even more differentiation, the same response as one alone, no response, or were inhibitory, dependent on the MDF pair and its concentration. The data suggests complicated receptor interactions. |
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Keywords: | differentiation factors midgut stem cells Heliothis virescens Lymantria dispar |
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