The second messengers involved in the signal transduction for Schistocerca gregaria, ion transport peptide (Schgr-ITP) that regulates ion and fluid transport across the ileum of the desert locust S. gregaria, were measured using competitive enzyme-linked immunosorbent assays (ELISAs). Synthetic Schgr-ITP elevates intracellular levels of both cyclic AMP and cyclic GMP, measured over a 15 min period in the presence of 3-isobutyl-1-methylxanthine, in a dose-dependent manner.
View Article and Find Full Text PDFProbing of a host and ingestion of a blood-meal in a fifth instar Rhodnius prolixus results in a cascade of tightly integrated events. The huge blood-meal is pumped into the anterior midgut during feeding, then modified by diuresis and stored until it is digested. While serotonin is known to be a diuretic hormone in R.
View Article and Find Full Text PDFThe nomenclature currently in use for insect neuropeptide and peptide hormone families is reviewed and suggestions are made as to how it can be rationalized. Based upon this review, a number of conventions are advanced as a guide to a more rationale nomenclature. The scheme that is put forward builds upon the binomial nomenclature scheme proposed by Raina and Gäde in 1988, when just over 20 insect neuropeptides had been identified.
View Article and Find Full Text PDFIn insects, a family of peptides with sequence homology to the vertebrate calcitonins has been implicated in the control of diuresis, a process that includes mixing of the hemolymph. Here, we show that a member of the insect calcitonin-like diuretic hormone (CLDH) family is present in the American lobster, Homarus americanus, serving, at least in part, as a powerful modulator of cardiac output. Specifically, during an ongoing EST project, a transcript encoding a putative H.
View Article and Find Full Text PDFThe insect arginine vasopressin-like (AVPL) peptide is of special interest because of its potential function in the regulation of diuresis. Genome sequences of the red flour beetle Tribolium castaneum yielded the genes encoding AVPL and AVPL receptor, whereas the homologous sequences are absent in the genomes of the fruitfly, malaria mosquito, silkworm, and honeybee, although a recent genome sequence of the jewel wasp revealed an AVPL sequence. The Tribolium receptor for the AVPL, the first such receptor identified in any insect, was expressed in a reporter system, and showed a strong response (EC(50)=1.
View Article and Find Full Text PDFDiuresis in the blood-gorging hemipteran Rhodnius prolixus is under neurohormonal control and involves a variety of processes and tissues. These include ion and water movement across the epithelium of the crop and the Malpighian tubules, and muscle contractions of the crop, hindgut and dorsal vessel, which facilitate mixing of the blood-meal, mixing of the haemolymph, as well as the expulsion of waste. One of the neurohormones that might play a role in this rapid diuresis belongs to the calcitonin-like diuretic hormone (DH(31)) family of insect peptides.
View Article and Find Full Text PDFBackground: Grape berry development is a dynamic process that involves a complex series of molecular genetic and biochemical changes divided into three major phases. During initial berry growth (Phase I), berry size increases along a sigmoidal growth curve due to cell division and subsequent cell expansion, and organic acids (mainly malate and tartrate), tannins, and hydroxycinnamates accumulate to peak levels. The second major phase (Phase II) is defined as a lag phase in which cell expansion ceases and sugars begin to accumulate.
View Article and Find Full Text PDFAcheta domesticus is reported to have an antidiuretic hormone that reduces Malpighian tubule secretion. Identified peptides known to work in this way (Tenmo-ADFa and ADFb, and Manse-CAP(2b)) were tested as candidates for the unidentified hormone, along with their second messenger, cyclic GMP. Only Tenmo-ADFb was active, but was diuretic, as was 8-bromo cyclic GMP.
View Article and Find Full Text PDFThe impact of water deficit and salt stress on two important wine grape cultivars, Chardonnay and Cabernet Sauvignon, was investigated. Plants were exposed to increasing salinity and water deficit stress over a 16 d time period. Measurements of stem water potentials, and shoot and leaf lengths indicated that Chardonnay was more tolerant to these stresses than Cabernet Sauvignon.
View Article and Find Full Text PDFGrapes are grown in semiarid environments, where drought and salinity are common problems. Microarray transcript profiling, quantitative reverse transcription-PCR, and metabolite profiling were used to define genes and metabolic pathways in Vitis vinifera cv. Cabernet Sauvignon with shared and divergent responses to a gradually applied and long-term (16 days) water-deficit stress and equivalent salinity stress.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2006
At the end of each developmental stage, insects perform the ecdysis sequence, an innate behavior necessary for shedding the old cuticle. Ecdysis triggering hormones (ETHs) initiate these behaviors through direct actions on the CNS. Here, we identify the ETH receptor (ETHR) gene in the moth Manduca sexta, which encodes two subtypes of GPCR (ETHR-A and ETHR-B).
View Article and Find Full Text PDFInsect Biochem Mol Biol
November 2005
Juvenile hormone (JH) diol kinase (JHDK) is an important enzyme involved in the JH degradation pathway. Bombyx mori (Bommo)-JHDK cDNA (637bp) contains an open reading frame encoding a 183-amino acid protein, which reveals a high degree of identity to the two previously reported JHDKs. JHDK is similar to GTP-binding proteins with three conserved sequence elements involved in purine nucleotide binding, contains eight alpha-helices and three EF-hand motifs, and resembles the three-dimensional model of 2SCP and some other calcium-binding proteins.
View Article and Find Full Text PDFMosquito natriuretic peptide (MNP), an uncharacterised peptide from the yellow fever mosquito, Aedes aegypti, acts via cyclic AMP to stimulate secretion of Na+-rich urine by opening a Na+ conductance in the basolateral membrane of Malpighian tubule principal cells. Corticotropin releasing factor (CRF)-related peptides and calcitonin (CT)-like diuretic peptides use cyclic AMP as a second messenger and were therefore considered likely candidates for MNP. BLAST searches of the genome of the malaria mosquito Anopheles gambiae, gave sequences for the CRF-related peptide Anoga-DH44 and the CT-like peptide Anoga-DH31, which were synthesised and tested for effects on Malpighian tubules from An.
View Article and Find Full Text PDFThe Drosophila orphan G protein-coupled receptor encoded by CG17415 is related to members of the calcitonin receptor-like receptor (CLR) family. In mammals, signaling from CLR receptors depend on accessory proteins, namely the receptor activity modifying proteins (RAMPs) and receptor component protein (RCP). We tested the possibility that this Drosophila CLR might also require accessory proteins for proper function and we report that co-expression of the mammalian or Drosophila RCP or mammalian RAMPs permitted neuropeptide diuretic hormone 31 (DH31) signaling from the CG17415 receptor.
View Article and Find Full Text PDFWe investigated second messengers involved in the action of the CRF-related peptide Dippu-DH46 and the calcitonin-like peptide Dippu-DH31 in Diploptera punctata. Dippu-DH46 causes a dose-dependent increase in intracellular cAMP levels, its diuretic activity is mimicked by cAMP agonists, but is attenuated by Rp-cAMPS. Dippu-DH46 acts synergistically with kinins and thapsigargin; both mobilize intracellular Ca2+.
View Article and Find Full Text PDFThe blood-feeding bug, Rhodnius prolixus, ingests large blood meals, then undergoes a period of rapid diuresis which is under neurohormonal control. In both cockroach (Diploptera punctata) and fruit fly (Drosophila melanogaster) a calcitonin-like DH31 neuropeptide has been identified [Coast GM, Webster SG, Schegg KM, Tobe SS, Schooley DA. The Drosophila melanogaster homologue of an insect calcitonin-like diuretic peptide stimulates V-ATPase activity in fruit fly Malpighian tubules.
View Article and Find Full Text PDFThe conjugation of a ligand to an enzyme is often a necessary step in the development of enzyme-linked immunoassays. Such conjugation is typically accomplished by reacting an amine with a carboxyl functional group in the presence of an activator such as a carbodiimide. However, one enzyme's free carboxyl groups often react with another's free amino groups and a large amount of cross-linking between enzyme molecules occurs; few discrete enzyme molecules conjugated only to the ligand of interest are produced.
View Article and Find Full Text PDFThe mechanism of action of Tenebrio molitor antidiuretic factor 'a' (Tenmo ADFa) was explored in isolated Malpighian tubules of Aedes aegypti. In the Ramsay assay of fluid secretion, Tenmo ADFa (10(-9) mol l(-1)) significantly inhibited the rate of fluid secretion from 0.94 nl min(-1) to 0.
View Article and Find Full Text PDFWe isolated from head extracts of Tenebrio molitor a peptide that inhibits fluid secretion by the Malpighian tubules of this insect. This second antidiuretic factor, ADFb, like the previously published ADFa, works through cyclic GMP as a second messenger. It has primary structure Tyr-Asp-Asp-Gly-Ser-Tyr-Lys-Pro-His-Ile-Tyr-Gly-Phe-OH with an EC(50) of approximately 240 pM in a fluid secretion assay.
View Article and Find Full Text PDFWe report an improved method for the synthesis of high specific activity insect [10-(3)H]juvenile hormones (JH) I, II, and III which affords both enantiomers of each in high optical purity. A synthetic route for JH I was modified to give higher yields and purity. We increased the specific activity of the synthetic [10-(3)H]JHs using normal phase liquid chromatography optimized to give near baseline resolution of [10-(3)H]JHs and unlabeled JHs.
View Article and Find Full Text PDFManduca sexta juvenile hormone diol kinase (JHDK) catalyzes the conversion of juvenile hormone (JH) diol to JH diol phosphate. JHDK may be the first example of a phosphotransferase directly involved in the catabolism and inactivation of a lipid-soluble hormone. JHDK is an enzyme crucial for secondary metabolism of JH and possesses high specificity and catalytic efficiency for JH diol.
View Article and Find Full Text PDFThe gene sequence of Manduca sexta juvenile hormone diol kinase (JHDK) codes for an enzyme that has 59% sequence identity to Drosophila melanogaster sarcoplasmic calcium-binding protein-2 (dSCP2). JHDK and dSCP2 are similar to G-proteins with three conserved sequence elements involved in purine nucleotide binding. Both proteins contain two pairs of EF-hand motifs.
View Article and Find Full Text PDFThe rapid post-feeding diuresis of Rhodnius prolixus is under neurohormonal control and involves the integrated activity of the crop, Malpighian tubules and hindgut. One of the factors which is involved in this rapid diuresis is serotonin, however a peptide(s) is also considered to be involved. In other insects, corticotropin releasing factor (CRF)-like and kinin-like, calcitonin-like peptides and CAP(2b) have been demonstrated to be diuretic factors/hormones.
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