INSECT TACHYKININ-RELATED NEUROPEPTIDES - DEVELOPMENTAL-CHANGES IN EXPRESSION OF CALLITACHYKININ ISOFORMS IN THE CENTRAL-NERVOUS-SYSTEM ANDINTESTINE OF THE BLOWFLY, CALLIPHORA-VOMITORIA

We have analyzed the relative distribution of tachykinin-related pepti des (TRPs) in extracts of adult brains, thoracico-abdominal ganglia, a nd midguts and of the larval central nervous system of the blowfly Cal liphora vomitoria using high performance liquid chromatography (HPLC) in combination with radioimmunoassay (RIA). The RIA employed antisera to the insect TRPs, locus-tatachykinin I (LomTK I) and callitachykinin II (CavTK II). For identification of the two known blowfly tachykinin s we monitored the retention times of synthetic CavTK I and CAVTK II a s a reference. With the CavTK II antiserum, all assayed tissues displa yed two immunoreactive HPLC fractions with exactly the same retention times as synthetic CavTK I and CavTK II, respectively. An additional i mmunoreactive fraction eluting earlier than the reference peptides was detected in the adult midgut extract. When assaying the HPLC fraction s with antiserum to LomTK I, we obtained the same patterns of immunore activity except that now the early eluting material was detectable in all the adult extracts. In addition, in the larval central nervous sys tem, a third major immunoreactive component was displayed using the Lo mTK RIA and a fourth detected with the CavTK II RIA. We conclude that CavTK I and II are present at a ratio of about 1:1 in all assayed tiss ues and that two or three additional unidentified tachykinin-immunorea ctive peptides may exist. One of these was seen in the adult tissues; the others appear to be specific for the larval central nervous system (CNS). The RIA was also utilized to determine the total amount of Cav TK-immunoreactive material in adult brain, thoracic-abdominal ganglia, and midgut as well as in larval CNS and intestine. The adult CNS cont ained about seven times more CavTK-immunoreactive material than the la rval CNS, and the adult midgut contained 15 times more than the larval intestine. Correlated with these RIA results, many fewer CavTK immuno reactive endocrine cells were labeled in the larval midgut and fewer n eurons in the larval CNS than in the Corresponding tissues of adults. (C) 1997 Wiley-Liss, Inc.