The cockroach-type or A-type allatostatins are inhibitory insect neuropeptides with the C-terminal sequence Tyr/Phe-X-Phe-Gly-Leu-NH 2 . Here, we have cloned an A-type allatostatin receptor from the silkworm Bombyx mori (BAR). BAR is 361 amino acid residues long, has seven transmembrane domains, shows 60% amino acid residue identity with the first Drosophila allatostatin receptor (DAR-1), and 48% identity with the second Drosophila allatostatin receptor (DAR-2). The BAR gene has two introns and three exons. These two introns coincide with and have the same intron phasing as two introns in the DAR-1 and DAR-2 genes, showing that the three receptors are not only structurally but also evolutionarily related. Furthermore, we have cloned a Bombyx allatostatin preprohormone that contains eight different Atype allatostatins. Chinese hamster ovary cells permanently transfected with BAR DNA react on the addition of 4 ؋ 10 ؊9 M Bombyx A-type allatostatins with a second messenger cascade (measured as bioluminescence), showing that BAR is a functional A-type allatostatin receptor. Southern blots suggest that Bombyx has at least one other BAR-related gene in addition to the BAR gene described in this paper. Northern blots and quantitative reverse transcriptase-polymerase chain reaction of different larval tissues show that BAR mRNA is mainly expressed in the gut and to a much lesser extent in the brain. To our knowledge, this is the first report on the molecular cloning and functional expression of an insect gut/brain peptide hormone receptor.Insects constitute a large group of animals (more than 70% of all animal species are insects) and are ecologically and economically extremely important, because most flowering plants depend on insects for their pollination (honeybees alone pollinate 20 billion dollars worth of crop yearly in the United States). But insects can also be severe pests in agriculture, destroying 30% of our potential annual harvest, and can be vectors for major diseases such as malaria, sleeping disease, and yellow fever. Despite the importance of insects, however, their molecular endocrinology is not well understood. This will certainly change after the recent publication of the Drosophila genome (1, 2), which represents a breakthrough for our understanding of virtually all aspects of insects. For the insect molecular endocrinology field, e.g. one can anticipate that the major future advances will occur by "mining" of the "Drosophila Genome Project" data base and cloning of important key proteins involved in insect endocrinology (3-9).Although most initial findings will be made in Drosophila, one can expect that these discoveries also will have their impacts on our understanding of the molecular endocrinology of other insects. Although Drosophila offers many important advantages for studying the molecular biology and genetics of an insect (a sequenced genome; the presence of numerous mutants, including knock-out mutants (7); and the possibility of creating transgenic animals), it is relatively small, which m...

Arginine vasopressin (AVP) and oxytocin (OT) mRNAs are targeted to the axonal compartment of rat hypothalamic magnocellular neurons. Salt-loading results in a considerable rise in hypothalamic and axonal AVP mRNA but only a moderate increase for axonal OT mRNA. Here we report that hypoosmolality gives rise to a rapid decrease of axonal AVP encoding transcripts to undetectable levels after 2 weeks. The levels of OT mRNA in the axonal compartment did not change significantly. In the hypothalamus the mRNA for AVP also decreased. The size of the poly(A) tract of AVP encoding transcripts appeared to be strictly correlated with plasma osmolality. In contrast, the amount and size of OT encoding mRNAs were only moderately or not influenced by hypoosmolar stimuli.infusion of the AVP V2-receptor agonist 1-deamino-[8-D-arginine] vasopressin (DDAVP) by use of subcutaneously implanted osmotic minipumps combined with a liquid diet to induce overhydration. In the hypothalamus hypoosmolality induced a reduction in both the abundance of AVP mRNA and the length of its poly(A) tract; the latter appears to be strictly correlated with plasma osmolality. In addition, a rapid and steady depletion of the axonal AVP mRNA pool was observed with undetectable levels after 2 weeks of overhydration. Surprisingly, the oxytocinergic system was considerably less affected by this treatment. Materials and methods

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