Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Insect Hormones”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 883 records · Page 49Linked to original sources
PubMed2001

High-level expression of a functional single-chain human chorionic gonadotropin-luteinizing hormone receptor ectodomain complex in insect cells.

Reproductive capacity in primates is dependent on the high-affinity binding of the glycoprotein hormones LH and human (h)CG to the large ectodomain (ECD) of their common receptor (LHR). Our understanding of the precise molecular determinants of hormone binding is limited, because there are no structural data for any of the glycoprotein hormone receptors. Overexpression of the ECD of the receptor has been attempted in various expression systems. Prokaryotic expression does not yield properly folded ECD. Eukaryotic expression, on the other hand, results in mostly heterogeneous, intracellularly trapped protein, but the secreted ECD is completely folded. Accordingly, we have tethered the single-chain hormone, yoked hCG, to the N terminus of LHR-ECD (yoked hormone-extracellular domain). Yoked hCG is secreted at high levels; binds LHR with high affinity; and, when tethered to the N terminus of full-length LHR, it binds and constitutively activates the receptor. Using recombinant baculovirus, yoked hormone-extracellular domain is secreted from insect cells at levels greater than 1 microg/ml, nearly 20-fold higher than that previously reported in eukaryotic expression systems. The protein was purified and binds exogenous (125)I-hCG with high affinity but, significantly, only after protease treatment to remove the tethered hormone. Thus, the fusion protein seems to form a functional hormone-receptor complex that is expressed at levels sufficient for its biophysical characterization.

Animals↗
PubMed2002

Neuropeptides and peptide hormones in Anopheles gambiae.

The African malaria mosquito, Anopheles gambiae, is specialized for rapid completion of development and reproduction. A vertebrate blood meal is required for egg production, and multiple feedings subsequently allow transmission of malaria parasites, Plasmodium spp. Regulatory peptides from 35 genes annotated from the A. gambiae genome likely coordinate these and other physiological processes. Plasmodium parasites may affect actions of newly identified insulin-like peptides, which coordinate growth and reproduction of its vector, A. gambiae, as in Drosophila melanogaster, Caenorhabditis elegans, and mammals. This genomic information provides a basis to expand understanding of hematophagy and pathogen transmission in this mosquito.

Amino Acid Sequence↗
PubMed1996

Immunocytochemical distribution of locustamyoinhibiting peptide (Lom-MIP) in the nervous system of Locusta migratoria.

Locustamyoinhibiting peptide (Lom-MIP) is one of the 4 identified myoinhibiting neuropeptides, isolated from brain-corpora cardiaca-corpora allata-suboesophageal ganglion complexes of the locust, Locusta migratoria. An antiserum was raised against Lom-MIP for use in immunohistochemistry. Locustamyoinhibiting peptide-like immunoreactivity (Lom-MIP-LI) was visualized in the nervous system and peripheral organs of Locusta migratoria by means of the peroxidase-antiperoxidase method. A total of 12 specific immunoreactive neurons was found in the brain. Processes of these neurons innervate the protocerebral bridge the central body complex and distinct neuropil areas in the proto- and tritocerebrum but not in the deuterocerebrum nor in the optic lobes. The glandular cells of the corpora cardiaca, known to produce adipokinetic hormones, are contacted by Lom-MIP-LI fibers. The corpora allata were innervated by the nervus corporis allati I containing immunoreactive fibers. Lom-MIP-LI cell bodies were also found in the subesophageal ganglion, the metathoracic ganglion and the abdominal ganglia I-IV. In peripheral muscles, Lom-MIP-LI fibers innervate the heart, the oviduct, and the hindgut. In the salivary glands, Lom-MIP-LI was detected in the intracellular ductule of the parietal cells. Possible functions of Lom-MIP are discussed.

Animals↗
PubMed1995

Analysis of ecdysteroid action in Malacosoma disstria cells: cloning selected regions of E75- and MHR3-like genes.

IPRI-MD-66 (MD-66) cells respond to 20-hydroxyecdysone (20E, 4 x 10(-6) M) in the medium by producing cytoplasmic extensions, clumping and attaching themselves to the substrate. These morphological changes are at a maximum by 6 days post treatment. Degenerate oligonucleotides, designed on the basis of conserved amino acid sequences in the DNA and ligand binding regions of the members of the steroid hormone receptor superfamily, were used in RNA-PCR to isolate two cDNA fragments, Malacosoma disstria hormone receptor 2 (MdHR2) and Malacosoma disstria hormone receptor 3 (MdHR3) from the MD-66 cells. Comparison of deduced amino acid sequences of these cDNA fragments with the members of the steroid hormone receptor superfamily showed that MdHR2 is most closely related to E75 proteins of Manduca sexta, Galleria mellonella and Drosophila melanogaster. The MdHR3 is most closely related to Manduca hormone receptor 3 (MHR3), Galleria hormone receptor 3 (GHR3) and Drosophila hormone receptor 3 (DHR3) proteins. At a concentration of 4 x 10(-6) M, 20E induces the expression of MdHR2 and MdHR3 beginning at 3 h, reaching maximum levels in 12 h and declining in 24 h. MdHR2 binds to a 2.5 kb mRNA, whereas MdHR3 binds to a 4.5 kb mRNA. Based on sequence similarity, RNA size and ecdysone inducibility, we conclude that these cDNA fragments, cloned from MD-66 cells, are regions of E75- (MdHR2) and MHR3- (MdHR3) like genes.

Amino Acid Sequence↗
PubMed2003

Allelic variation in the hemolymph juvenile hormone binding protein gene of Manduca sexta.

Peripheral distribution of the insect juvenile hormones (JHs) requires hemolymph transport proteins. A comparison of three strains of the tobacco hornworm Manduca sexta indicates that hemolymph JH binding protein (hJHBP) levels in the Madison wild-type (Mwt) strain are significantly higher than in the black larval mutant (bl) and Seattle wild-type (Swt) strains. To correlate differences in hJHBP levels between strain phenotypes with the hJHBP locus, we sequenced 8.4 kb of the hJHBP gene locus from each strain. Snb, an allele found in the Swt and bl strains, contains a 408 bp repetitive nuclear element flanked by 15 bp direct repeats. Mating studies coupled with molecular genotyping demonstrate that the presence of Snb correlates with a twofold lower hJHBP level relative to the allele found in the Mwt strain. Despite the lower hJHBP levels in individuals carrying the Snb gene, hemolymph levels of JH do not appear to be significantly affected.

Alleles↗
PubMed2000

[Headcase gene--proliferation or hormonal control?].

A new insertion allele of the hdc gene was isolated and described. The nucleotide sequence of the coding region had no detectable homology with genomic DNA of any other Drosophila species, except for D. mauritiana. Gene expression was found both in adult testes and ovaries and at embryonic and larval stages. This expression pattern exhibits a strong similarity to that of cell-cycle genes. In contrast to cycE (a typical cell-cycle gene), which leads to expression termination after in vivo culturing of the wing disk, hdc did not arrest expression. It is concluded that hdc is a species-specific differentiation gene, whose regulatory activity in the development of an organism differs from that of proliferation genes.

Animals↗
PubMed2001

Differentially expressed regulatory genes in honey bee caste development.

In the honey bee, an eminently fertile queen with up to 200 ovarioles per ovary monopolizes colony level reproduction. In contrast, worker bees have only few ovarioles and are essentially sterile. This phenotype divergence is a result of caste-specifically modulated juvenile hormone and ecdysteroid titers in larval development. In this study we employed a differential-display reverse transcription (DDRT)-PCR protocol to detect ecdysteroid-regulated gene expression during a critical phase of caste development. We identified a Ftz-F1 homolog and a Cut-like transcript. Ftz-F1 could be a putative element of the metamorphic ecdysone response cascade of bees, whereas Cut-like proteins are described as transcription factors involved in maintaining cellular differentiation states. The downregulation of both factors can be interpreted as steps in the metamorphic degradation of ovarioles in worker-bee ovaries.

Amino Acid Sequence↗
PubMed1988

Synthesis of two storage proteins during larval development of the tobacco hornworm, Manduca sexta.

Studies of synthesis and accumulation of the two storage proteins arylphorin and female-specific protein (FSP) during the final two larval instars of the tobacco hornworm showed both stage and temporal specificity. Arylphorin was present in both stages, but its synthesis ceased during the molt, during starvation, and at the wandering stage, and then resumed about 24 hr after the onset of feeding. During the larval molt about 25% of injected iodinated arylphorin was incorporated into the newly forming fifth instar cuticle. The cessation of arylphorin synthesis was mimicked by exposure of the fat body to 1 microgram/ml 20-hydroxyecdysone (20HE) in complete Grace's medium or to dilutions of Grace's medium greater than 50%. Lower concentrations of 20HE were ineffective, indicating that the cessation of synthesis in vivo was likely due to a combination of lack of excess nutrients and the hormonal milieu. The female-specific protein was not synthesized until the final larval instar, appearing first in females on Day 2 and later in males at the time of wandering, with synthesis continuing throughout the prepupal period. In vitro studies showed that this protein was synthesized as a 620-kDa protein, and then during secretion a 730-kDa immunoreactive form also appeared. Synthesis of FSP was inhibited by exposure of Day 2 fat body to 1 microgram/ml 20HE for 24 hr. Ligation followed by 20HE infusion showed that the disappearance of FSP from the hemolymph during the prepupal period was controlled by the rising ecdysteroid titer.

Adipose Tissue↗
PubMed1993

Development of recombinant viral insecticides by expression of an insect-specific toxin and insect-specific enzyme in nuclear polyhedrosis viruses.

As supplements to classical chemical insecticides, two approaches to develop recombinant baculovirus insecticides are described. In one approach an insect-specific toxin is expressed leading to a dramatic reduction in time to death. In the second approach an insect juvenile hormone esterase is expressed which leads to a reduction in feeding. Modifications of the wildtype esterase led to viruses which reduced the time to death as effectively as did the toxin-expressing virus. In both cases existing recombinant viruses are viewed as leads, and approaches to further improvement in the engineered viruses are suggested. Many of these approaches are based on analogy with the development of classical synthetic insecticides. Using these viruses as examples, the potential utility and limitations of recombinant viruses and other biological insecticides are discussed.

Amino Acid Sequence↗
PubMed1999

Prothoracicotropic activity of SBRPs, the insulin-like peptides of the saturniid silkworm Samia cynthia ricini.

Synthesis and secretion of the insect molting hormone ecdysteroid in the prothoracic glands (PGs) are stimulated by the prothoracicotropic hormone (PTTH) secreted by the brain. Bombyxins, insulin-like peptides of the silkworm Bombyx mori, show prothoracicotropic activity when administered to the saturniid silkworm Samia cynthia ricini, but they are inactive to B. mori itself. Recently, the genes for the bombyxin homologs of S. cynthia ricini (referred to as Samia bombyxin-related peptides, SBRPs) were cloned. To examine the prothoracicotropic activity of SBRPs on S. cynthia ricini, we synthesized two representative molecules, SBRP-A1 and -B1. They promoted pupa-to-adult development with ED(50) of 50 and 10 ng/pupa (EC(50) of 5 and 1 nM), respectively.

Amino Acid Sequence↗
PubMed2003

Changes in lipophorins are related to the activation of phenoloxidase in the haemolymph of Locusta migratoria in response to injection of immunogens.

In Locusta migratoria, activation of phenoloxidase in the haemolymph in response to injection of laminarin is age-dependent: being absent in fifth instar nymphs and newly emerged adults, and only becoming evident four days after the final moult. This pattern of change in phenoloxidase activation correlates with the pattern of change in the concentration of apolipophorin-III (apoLp-III) in the haemolymph. Injection of a conspecific adipokinetic hormone (Lom-AKH-I) has no effect on the phenoloxidase response in nymphs or newly emerged adults but, in adults older than four days, co-injection of the hormone with laminarin prolongs the activation of phenoloxidase in the haemolymph: a similar enhancement of the response to laminarin is observed in locusts that have been starved for 48 h but not injected with AKH-I. During most of the fifth stadium, injection of laminarin results in a decrease in the level of prophenoloxidase in the haemolymph; an effect that is not observed in adults of any age. Marked changes in the concentration of apoLp-III, and the formation of LDLp in the haemolymph, are observed after injection of laminarin (or LPS) and these are remarkably similar, at least qualitatively, to those that occur after injection of AKH-I. The involvement of lipophorins in the activation of locust prophenoloxidase in response to immunogens is discussed.

Animals↗
PubMed1996

Cloning, expression, and hormonal regulation of an insect beta-N-acetylglucosaminidase gene.

Chitinolytic enzymes such as beta-N-acetylglucosaminidases are major hydrolases involved in insect molting. By screening a Manduca sexta (tobacco hornworm) cDNA library with an antibody against beta-N-acetylglucosaminidase from molting fluid of M. sexta pharate pupae, several putative cDNA clones for this enzyme were isolated. The longest of the cDNA clones has an insert of approximately 3 kb, and the complete nucleotide sequence was determined. Because this clone is missing the initiation codon and nucleotides corresponding to the leader peptide, the mRNA 5'-end sequence was determined by PCR (polymerase chain reaction) amplification and cycle sequencing. The sequence of the encoded protein from positions 23 to 35 is identical to the NH2-terminal sequence of one of the beta-N-acetylglucosaminidases isolated from pharate pupal molting fluid. The amino acid sequence is similar to those of silkworm, human, mouse, bacterial, and several other beta-N-acetylglucosaminidases. Two highly conserved regions in the amino acid sequence were found in all members of this family. Southern blot analysis suggested that the number of genes in the Manduca genome closely related to the cDNA clone may be as few as one. The beta-N-acetylglucosaminidase gene is expressed most abundantly in epidermal and gut tissues on days 6 and 7 of fifth instar larvae. Injection of 20-hydroxyecdysone induced expression of the beta-N-acetylglucosaminidase gene, whereas topical application of the juvenile hormone analog, fenoxycarb, suppressed the inductive effect of molting hormone.

Acetylglucosaminidase↗
PubMed1990

The Drosophila IMP-E2 gene encodes an apically secreted protein expressed during imaginal disc morphogenesis.

During metamorphosis, the steroid hormone 20-hydroxyecdysone induces morphogenesis of imaginal discs, including the formation of appendages. IMP-E2 is an ecdysone-dependent, single-copy Drosophila gene, whose transcripts accumulate rapidly in imaginal discs in response to the hormone. The IMP-E2 product is secreted at the apical surface of the disc epithelium in association with disc morphogenesis. The product is also secreted apically by the embryonic ectoderm during mid embryogenesis. The deduced primary structure of the protein reveals the presence of 16, short 3-amino acid repeat motifs (such as EIK and EVK) toward the N-terminal end of the protein, and three long, uncharged domains, containing 43 to 78 residues each, toward the C-terminal end. The predicted structure of the protein suggests that it may participate in multimolecular aggregates. Although the temporal and spatial expression of the IMP-E2 gene are consistent with a role in disc morphogenesis, its specific functions remain to be determined.

Amino Acid Sequence↗
PubMed1997

The nuclear receptor homologue Ftz-F1 and the homeodomain protein Ftz are mutually dependent cofactors.

Nuclear hormone receptors and homeodomain proteins are two classes of transcription factor that regulate major developmental processes. Both depend on interactions with other proteins for specificity and activity. The Drosophila gene fushi tarazu (ftz), which encodes a homeodomain protein (Ftz), is required zygotically for the formation of alternate segments in the developing embryo. Here we show that the orphan nuclear receptor alphaFtz-F1 (ref. 3), which is deposited in the egg during oogenesis, is an obligatory cofactor for Ftz. The two proteins interact specifically and directly, both in vitro and in vivo, through a conserved domain in the Ftz polypeptide. This interaction suggests that other nuclear receptor/homeodomain protein interactions maybe important and common in developing organisms.

Alleles↗
PubMed1998

Identification of a steroidogenic neurohormone in female mosquitoes.

In the female mosquito, Aedes aegypti, neurohormones are released from the brain in response to a blood meal and stimulate the ovaries to secrete ecdysteroid hormones, which modulate yolk protein synthesis in the fat body. Neuropeptides with this bioactivity were isolated from head extracts, and partial sequences from these peptides when aligned gave a 31-residue sequence at the amino terminus. Oligonucleotide primers for this sequence were used to amplify with the polymerase chain reaction a genomic DNA product that hybridized to a clone from a head cDNA library. The cDNA encodes a 149-residue preprohormone that is processed into an 86-residue peptide, as indicated by the mass value obtained from the native peptide, with the expected amino-terminal sequence. After modification, the cDNA for the putative neurohormone was expressed in a bacterial system, and the purified peptide had high specific activity in bioassays, thus confirming that it is a steroidogenic gonadotropin, the first to be identified for invertebrates.

Aedes↗
PubMed1995

Characterization of the adipokinetic hormone receptor form the fat body of Manduca sexta.

A tritium labeled Manduca sexta adipokinetic hormone (M-AKH) was synthesized (pE-L-T-[p3H]F-T-S-S-W-G-NH2) (specific activity 27 Ci/mmol) which was fully active in a bioassay. It was used in a filtration based binding assay to characterize the M-AKH receptor from the fat body of M. sexta. Membrane fractions were prepared from fat body and optimal binding conditions were determined. A Kd of 7.10(-10) M was determined and the receptor concentration estimated to be 0.5 pmol/mg membrane protein. No receptor binding was found when membranes were prepared from brain, heart or flight muscle of M. sexta or from fat body of the cockroach Blaberus discoidalis. However, specific binding was found with membrane preparations from the pterothoracic ganglion of M. sexta. The membranes from the ganglion had a much smaller number of binding sites than the fat body membranes, however, the binding was specific and observed in each experiment.

Amino Acid Sequence↗
PubMed2000

PTTH--a potential growth activator in silkworm, Bombyx mori L. for enhancing silk production.

In silkworm, prothoracicotropic hormone (PTTH), directly or indirectly controls silk production and spinning activity along with juvenile hormone (JH). An effort was made to exploit the potential of PTTH by indirectly activating silk gland for increasing silk productivity using short chain synthetic analogues of PTTH. The analogy in action was also established using PTTH extracted from the silkmoth. Different doses of 42 synthetic PTTH analogues, viz., 2.5, 5, 10 and 20ppm and 3.3 mg/ml of PTTH extracted from silkmoth heads were administered orally to V instar silkworm larvae (Race:KAxNB4D2 and PMxNB4D2) at 0-144 hr at an interval of 24 hr. The analysed data showed an improvement of about 14 - 23% in KA x NB4D2 and about 10-14% in PMxNB4D2 in respect of cocoon shell weight on administration of some of the synthetic PTTH analogues. The PTTH extracted from the adult brain also showed similar effect. The structural analogy of synthetic PTTHs (which improved the shell weight) with original PTTH and its probable mode of action in silkworm are discussed.

Amino Acid Sequence↗
PubMed2000

The pigmentotropic hormone [His(7)]-corazonin, absent in a Locusta migratoria albino strain, occurs in an albino strain of Schistocerca gregaria.

[His(7)]-corazonin has recently been identified in the corpora cardiaca (CC) of two locust species, the migratory locust, Locusta migratoria and the desert locust, Schistocerca gregaria, as the dark colour inducing neurohormone. Here, we investigate whether [His(7)]-corazonin occurs in the brain-CC axis of a Schistocerca albino strain. From data obtained by immunocytochemistry, injection experiments, chromatographic and mass spectrometric analysis of brain and CC tissues, it could be concluded that an albino strain of S. gregaria from Denmark contains authentic [His(7)]-corazonin. This was unequivocally demonstrated by sequencing the [His(7)]-corazonin-immunoreactive factor in albino Schistocerca brain-CC extracts with ESI-Qq-oa-TOF mass spectrometry. Albinism in this strain is hence not caused by the deficiency of authentic [His(7)]-corazonin in the brain-CC axis, nor by defects in release. Conversely to L. migratoria albinos, injection of [His(7)]-corazonin failed to induce dark pigmentation in Schistocerca albinos. Therefore, albinism in the investigated Schistocerca strain is likely to be situated at the level of the receptor, signal transduction mechanisms or of pigment biosynthesis.

Animals↗