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 937 records · Page 52Linked to original sources
PubMed2005

Testis ecdysiotropic peptides in Rhodnius prolixus: biological activity and distribution in the nervous system and testis.

In Rhodnius prolixus, testes from both pharate adult and adult males are shown to produce and release ecdysteroids in vitro. Proteinaceous brain extracts from these stages caused stimulation of ecdysteroid production by testes of unfed adults. Therefore, the brain of Rhodnius contains peptides with testis ecdysiotropic activity. The Lymantria testis ecdysiotropin (LTE) also stimulated the in vitro production of ecdysteroids by unfed adult testis but had no stimulatory effect on prothoracic glands. Western blot analysis of brain peptides using anti-LTE revealed the presence of several medium to small size immunoreactive peptides. Two of these peptides with sizes of 16.8 and 11.0 kDa were present only during pharate adult development and the adult stage. Immunohistochemical analysis using confocal laser scanning microscopy revealed abundant LTE-immunoreactive material in cytoplasmic granules of specific neurosecretory cells in the brain and suboesophageal ganglion and the epithelium of the testis sheath. Clusters of two cytologically distinct cell types were seen within the medial neurosecretory cells (MNC) and also a pair of neurons in the posterior protocerebrum. Feeding in both larvae and adult males resulted in massive release of LTE-immunoreactive material from the MNC cells, suggesting a role of LTE-related peptides in both larval-adult development and in male reproductive development. Release from the MNC cells of LTE-immunoreactive material exhibited a clear daily cycling during larval-adult development, which was synchronous with the rhythms of release of prothoracicotropic hormone and bombyxin reported previously. The testis sheath exhibited intense immunofluorescence in pharate adults and unfed adults, which disappeared following a blood meal. It is concluded that LTE-related peptides are developmentally regulated in several locations and may act as ecdysiotropins in Rhodnius. Those in the MNC cells are very probably classical hormones, i.e. are transported to their target sites via the insect haemolymph.

Animals↗
PubMed2003

Juvenile hormone esterase (JHE) from Tenebrio molitor: full-length cDNA sequence, in vitro expression, and characterization of the recombinant protein.

Juvenile hormone regulates the development and reproduction in a variety of insects. Juvenile hormone esterase (JHE) is a selective enzyme, which hydrolyzes the methyl ester of JH and alters its activity. In Tenebrio molitor, JHE has been previously purified from pupae and a partial cDNA was amplified by RT-PCR using fat body mRNA. The previous report indicated that several forms of the JHE protein were present in pupal homogenate. In this study, we report the full-length cDNA, which was obtained by RACE methods. The deduced protein sequence corresponds to peptides from two proteins of different molecular weights in the previous study. The coding region of the full-length cDNA was subcloned into the AcMNPV genome and high levels of expression of the JHE enzyme from the viral p10 promoter were demonstrated in cell culture. The majority of JHE is secreted from the cells as a soluble enzyme. The recombinant JHE enzyme was biochemically characterized. The recombinant protein appears by PAGE analysis as a monomer of approximately the same MW (66000) and pI (4.9) as was expected from the deduced amino acid sequence of the cDNA.

Amino Acid Sequence↗
PubMed1976

Hormonal studies of uridine utilization in an insect cell line CP-1268 derived from the codling moth Laspeyresia pomonella.

Ecdysterone decreased cellular growth and the incorporation of uridine into RNA following 4 days of hormone exposure. This hormone did not affect uridine incorporation following short-term exposure up to 25 hours. Juvenile hormone and farnesol both significantly decreased uridine uptake and incorporation into RNA; however, uridine uptake was inhibited to a greater extent than uridine incorporation. Cyclic AMP increased the incorporation of uridine into RNA but had no demonstrable effect on the uptake process. This stimulation was not the result of cAMP degradation products. Cyclic AMP and ecdysterone together produced a significant increase in uridine incorporation into RNA. These studies demonstrate the potential utilization of insect cell lines for studying the mode of action of insect developmental hormones.

Cell Line↗
PubMed1993

Adipokinetic hormone-induced influx of extracellular calcium into insect fat body cells is mediated through depletion of intracellular calcium stores.

Adipokinetic hormone I (AKH I) needs extracellular Ca2+ for its activating action on glycogen phosphorylase in locust fat body in vitro. TMB-8 reduces this AKH effect significantly, indicating that for a major part, hormone action also requires the mobilization of Ca2+ from intracellular stores. Using 45Ca2+, AKH was shown to stimulate both the influx and the efflux of Ca2+. Thapsigargin also enhances the influx of extracellular Ca2+ into the fat body cells, indicating that the stimulating effect of AKH on Ca2+ influx may be mediated through depletion of intracellular Ca2+ stores as well. AKH is known to enhance cAMP levels in locust fat body. We show that elevation of cAMP with forskolin or theophylline leads to activation of glycogen phosphorylase, both in the presence and in the absence of extracellular Ca2+. The present data are discussed in an attempt to elucidate further the mechanism underlying transduction of the hormonal signal in locust fat body.

Adenosine Monophosphate↗
PubMed2004

Rapid quantification of juvenile hormones and their metabolites in insect haemolymph by liquid chromatography-mass spectrometry (LC-MS).

A simple, fast and sensitive method was developed for routine determination of juvenile hormone (JH), JH diols and JH acids in insect haemolymph, by liquid chromatography-mass spectrometry (LC-MS). Sample clean-up involves the precipitation of proteins by methanol/isooctane (1:1, v/v), centrifugation and partial evaporation of the organic solvents. Since JH is bound to a carrier protein in the haemolymph, a binding protein (BP) assay was performed to ensure JH is removed during precipitation. The JH compounds were separated on a C(18) column (ReproSil-Pur ODS-3) by gradient elution with water and methanol in less than 22 min and analysed by electrospray mass spectrometry. Due to the high abundance of Na(+) in insect haemolymph, [M+Na](+) is primarily formed. The limit of detection and quantification was 6 and 20 pg for JHs, and 8 and 25 pg for JH diols, respectively. To demonstrate the applicability of the method to different insect orders, haemolymph samples from the Mediterranean field cricket ( Gryllus bimaculatus), the fall armyworm ( Spodoptera frugiperda), the pea aphid ( Acyrthosiphon pisum) and an ant species ( Myrmicaria eumenoides) were analysed.

Animals↗
PubMed2003

Developmental toxicity of methoprene and several degradation products in Xenopus laevis.

Methoprene is an insect juvenile growth hormone mimic, which inhibits pupation and is used for the control of emergent insect pests such as mosquitoes. Researchers have hypothesized that methoprene use in US may be a contributing factor to the recent increase in malformed amphibians. However, little is known concerning the developmental toxicity of methoprene and its degradation products in amphibians. In these studies, the aqueous stability and developmental toxicity of methoprene and several degradation products (methoprene acid, methoprene epoxide, 7-methoxycitronellal, and 7-methoxycitronellic acid) were examined. Xenopus laevis embryos (stage 8) were exposed to the test chemicals for 96 h. Assays were conducted under static renewal (24 h) conditions and chemical concentrations in water were measured at the beginning and end of the renewal periods. Methoprene exposure did not result in developmental toxicity at concentrations up to 2 mg/l, which is slightly higher than its water solubility. Methoprene acid, a relatively minor degradation product, produced developmental toxicity when concentrations exceeded 1.25 mg/l. Methoprene epoxide and 7-methoxycitronellal caused developmental toxicity at concentrations of 2.5 mg/l and higher. 7-Methoxycitronellic acid was not developmentally toxic at a test concentration as high as 30 mg/l. The five test chemicals had differential stability in aqueous solution that was in some instances affected by the presence of test organisms. These data indicate that methoprene and its degradation products are not potent development toxicants in X. laevis. This, in combination with the fact that field applications of sustained-release formulations of methoprene result in methoprene concentrations that do not typically exceed 0.01 mg/l, suggests that concerns for methoprene-mediated developmental toxicity to amphibians may be unwarranted.

Abnormalities, Drug-Induced↗
PubMed2006

Neverland is an evolutionally conserved Rieske-domain protein that is essential for ecdysone synthesis and insect growth.

Steroid hormones mediate a wide variety of developmental and physiological events in multicellular organisms. During larval and pupal stages of insects, the principal steroid hormone is ecdysone, which is synthesized in the prothoracic gland (PG) and plays a central role in the control of development. Although many studies have revealed the biochemical features of ecdysone synthesis in the PG, many aspects of this pathway have remained unclear at the molecular level. We describe the neverland (nvd) gene, which encodes an oxygenase-like protein with a Rieske electron carrier domain, from the silkworm Bombyx mori and the fruitfly Drosophila melanogaster. nvd is expressed specifically in tissues that synthesize ecdysone, such as the PG. We also show that loss of nvd function in the PG causes arrest of both molting and growth during Drosophila development. Furthermore, the phenotype is rescued by application of 20-hydroxyecdysone or the precursor 7-dehydrocholesterol. Given that the nvd family is evolutionally conserved, these results suggest that Nvd is an essential regulator of cholesterol metabolism or trafficking in steroid synthesis across animal phyla.

Amino Acid Sequence↗
PubMed1982

Hormonal control of renal functions in insects.

Insect Malpighian tubules secrete an isosmotic, KCl-rich primary urine containing low concentrations of most other blood solutes. Neuropeptide diuretic hormones (DH), possibly related to vasopressin, stimulate tubular fluid secretion by 2- to 200-fold in response to water loading, e.g., feeding. DH acts on tubules through cyclic AMP (cAMP) to stimulate salt transport without measurable change in osmotic permeability. Changes in composition of tubular secretion after stimulation and the possible control of DH release are discussed. Most of the water, ions, and metabolites in tubular secretion are normally reabsorbed by active mechanisms in the rectum, where the urine may finally become either hyposmotic or strongly hyperosmotic to the blood. A newly discovered neuropeptide, chloride transport-stimulating hormone, controls (via cAMP) reabsorption of the principal salt by stimulating K-dependent, electrogenic transport of Cl- across the apical cell border. Passive net absorption of K+ is thereby enhanced. Diuretic and antidiuretic factors may control osmotic permeability of the rectal wall and thereby influence the osmotic concentrations of the rectal absorbate and final urine. The increased recycling of a KCl-rich fluid through the Malpighian tubule-rectal system after feeding probably serves to clear the body of unwanted substances ingested with, and produced by, metabolism of the meal.

Animals↗
PubMed1999

Identification of a prothoracicostatic peptide in the larval brain of the silkworm, Bombyx mori.

Prothoracicotropic hormone (PTTH) stimulates ecdysteroid biosynthesis in the prothoracic gland (PG) of insects. A peptide inhibiting ecdysteroid biosynthesis in the PG was isolated from the extracts of 2,000 larval brains of the silkworm, Bombyx mori, using a protocol that included four reversed-phase high performance liquid chromatography procedures. The primary structure of this prothoracicostatic peptide (Bom-PTSP) was determined to be H-Ala-Trp-Gln-Asp-Leu-Asn-Ser-Ala-Trp-NH(2). This neuropeptide has the same sequence as Mas-MIP-I, a myoinhibitory peptide previously isolated from the ventral nerve cord of the tobacco hornworm, Manduca sexta, and is highly homologous with the N-terminal portion of vertebrate peptides of the galanin family. This peptide inhibited PTTH-stimulated ecdysteroidogenesis in the PG at both the spinning and feeding stages, which indicates that Bom-PTSP interferes with PTTH-stimulated ecdysteroidogenesis.

Amino Acid Sequence↗
PubMed1990

Postembryonic alteration of transmitter phenotype in individually identified peptidergic neurons.

Many neurons are now known to undergo dramatic morphological or biochemical changes long after they have completed differentiation and maturation. The ability of fully mature neurons to alter their transmitter phenotype has been amply demonstrated in culture, but direct in vivo data on single neurons have been difficult to obtain. Here we show that a set of 4 individually identified neurosecretory neurons in the moth Manduca sexta, previously demonstrated to contain the peptide hormone bursicon, also stain with a monoclonal antibody directed against 2 insect cardioacceleratory peptides (CAPs). These lateral cells exhibit CAP-like immunoreactivity in larvae but not in pupae or adults, in contrast to other CAP-containing neurons which are strongly immunoreactive in all postembryonic stages. Biochemical analyses using high-pressure liquid chromatography confirm that the lateral neurons in larvae contain CAP2, one of the CAPs. CAP measurements of cell clusters containing these cells indicate high levels only in caterpillars. When the same neurosecretory cells are individually dissected and assayed for CAP bioactivity, high CAP levels are again found in larvae, whereas the same neurons in pupae show no such CAP bioactivity. Simultaneous determinations of both bursicon and CAP levels in single lateral cells indicate that these cells express high levels of CAP activity and low amounts of bursicon in larvae yet are solely bursicon-containing in pupae and adults. Thus, by demonstrating that these cells alter their secretory profile in vivo during metamorphosis, our results confirm the notion that functionally mature neurons are capable of altering their transmitter expression after the completion of embryonic development.

Abdomen↗
PubMed1990

Characterization of affinity-purified juvenile hormone esterase from the plasma of the tobacco hornworm, Manduca sexta.

Juvenile hormone (JH) esterase found primarily in the hemolymph and tissues of insects is a low abundance protein involved in the ester hydrolysis of insect juvenile hormones, JHs. The enzyme was purified from the larval plasma of wild-type Manduca sexta using an affinity column prepared by binding the ligand, 3-[(4'-mercapto)butylthio]-1,1,1-trifluoropropan-2-one (MBTFP), to epoxy-activated Sepharose. The purification was greater than 700-fold with a 72% recovery, and the purified enzyme appeared as a single protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoelectrophoresis, reverse phase high performance liquid chromatography, and amino acid sequence analysis. The molecular weight was 66,000. The plasma JH esterase in wild-type, black, and white strains of M. sexta was similar when analyzed by immunotitration, wide range (pH 3.5-9.0) isoelectric focusing, and inhibition with MBTFP and 3-octylthio-1,1,1-trifluoropropan-2-one (OTFP). Inhibition studies revealed a sensitive and insensitive form (I50 = 10(-9) and 10(-6) M, respectively) in these three biotypes. Narrow range isoelectric focusing (pH 4.0-7.0) indicated the presence of two major isoelectric forms with pI values of 6.0 and 5.5, but their inhibition kinetics with OTFP and O,O-diisopropyl phosphorofluoridate were identical.

Amino Acid Sequence↗
PubMed1984

Induction of detoxication enzymes in insects.

Most of the known enzyme systems involved in the degradation of insecticides, other xenobiotics, and hormones of insects, appear to be inducible by various dietary chemicals, both plant-based and man-made. Although the understanding of the mechanism of this phenomenon comes almost entirely from studies of higher animals, there are good reasons to believe that the insect system is similar in most respects. If so, it involves a recognition system wherein exogenous chemicals in the insect's environment can stimulate the production of the enzymes that degrade them. Evidence is presented that some plant species and some plant allelochemicals are capable of such enhancement and that this is sufficient to increase the tolerance of an insect to various insecticides. It is also suggested that induction by plant chemicals may be involved in the insect's adaptation to its plant diet. Further understanding of the phenomenon, especially in regard to the cyclic nature of the process in plants and insects, may be of value in organizing pest management programs.

Adaptation, Physiological↗