K. Reichwald et al., EXPRESSION OF THE ALLATOSTATIN GENE IN ENDOCRINE-CELLS OF THE COCKROACH MIDGUT, Proceedings of the National Academy of Sciences of the United Statesof America, 91(25), 1994, pp. 11894-11898
Cockroach allatostatins are neuropeptides that have been isolated from
the brain of Diploptera punctata and shown to inhibit juvenile hormon
e production by the corpora allata. Enzyme-linked immunoassay and immu
nocytochemistry with antisera to two allatostatins, ASB2 (AYSYV-SEYKRL
PVYNFGL-NH2) and ASAL (APSGAQRLYGFGL-NH2), revealed that allatostatins
were located not only in the insect brain but also in several periphe
ral tissues including the cockroach midgut and hindgut. Allatostatin-l
ike immunoreactivity was found in nerve fibers of the stomatogastric n
ervous system as well as in intrinsic endocrine cells of the midgut. M
idgut extracts were shown to be biologically active in an allatostatin
bioassay and to contain several allatostatin-like peptides, including
the octadecapeptide ASB2, which was identified by mass spectrometry f
ollowing HPLC purification. Reverse transcription of brain mRNA follow
ed by PCR with degenerate oligonucleotides for ASB2 and ASAL yielded a
338-bp fragment of the allatostatin gene that encoded six allatostati
ns. In situ hybridization with this probe confirmed that an allatostat
in gene is expressed in intrinsic endocrine cells of the midgut. Rever
se transcription of midgut mRNA followed by PCR and sequencing of the
product revealed that the same gene is expressed in the midgut and in
the brain. Allatostatins are thus an example of insect ''brain-gut pep
tides'' and we suggest that their function may not be restricted to th
e regulation of juvenile hormone production.