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ARS Home » Research » Publications at this Location » Publication #126332
Title: PEPTIDES THAT ELICIT MIDGUT STEM CELL DIFFERENTIATION ISOLATED FROM CHYMOTRYPTIC DIGESTS OF HEMOLYMP FROM LYMANTRIA DISPAR PUPAE.

Author
item LOEB, MARCIA
item JAFFE, HOWARD - NIH

Submitted to: Archives of Insect Biochemistry and Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/6/2002
Publication Date: N/A
Citation: N/A

Interpretive Summary: The midgut is the largest organ in the insect larva. All food, toxins and pesticides are processed in the midgut. Therefore, it is important to know as much as possible about insect gut physiology in order to understand how the pesticides and larvicides eaten by an insect function and how they can be made more effective. This work was done using stem cells isolated from the midgut of the pest insect, the tobacco budworm, which we are able to grow in culture. These stem cells appear to multiply and change into mature, working gut cells in response to cellular factors in ways similar to mammalian stem cells. However, mammalian factors are not effective in insect tissue. Here we describe the characterization of 2 insect factors isolated from insect pupal blood that induce midgut stem cells to mature. Scientists studying insect development will be interested in this work as a possible model for stem cell regulation.

Technical Abstract: Isolated stem cells of Heliothis virescens, cultured in vitro, were induced to differentiate by either of 2 peptides identified from a digest of hemolymph from newly pupated Lymantria dispar. The hemolymph was boiled, and the supernatant was subjected to digestion with chymotrypsin to liberate the active peptides from hemolymph proteins. Partial purification was obtained by filtration through size exclusion filters. The most active preparation was subsequently subjected to a series of 3 RP-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, and the synthetic compounds proved active in a dose dependent manners. 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 2x 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, dependant on the MDF pair and its concentration. The data suggests complicated receptor interactions.