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 595 records · Page 33Linked to original sources
PubMed1991

Physical characterization and sequence identification of the ovary maturating parsin. A new neurohormone purified from the nervous corpora cardiaca of the African locust (Locusta migratoria migratorioides.

A novel neurohormone, which anticipates ovarian maturation, was recently purified using liquid chromatography from the African locust nervous corpora cardiaca. Both its function and production by the pars intercerebralis of Locusta migratoria lead to its name, the ovary maturating parsin (Lom OMP). In this study, the Lom OMP was physically and chemically characterized. Its multiply charged ion spectrum was interpreted as two peaks of quite equal size having molecular masses of 6923.4 Da (major peak) and 6907.3 Da. The Lom OMP presented no periodic secondary structure according to the far ultraviolet circular dichroism spectrum obtained. It is composed of 65 amino acids and included a high concentration of alanine but is devoid of cysteine, isoleucine, methionine, lysine and threonine. The amino acid sequence indicated only one microheterogeneity, observed at position 26, consisted in the replacement of serine by alanine. The calculated Mr of the two acidic isoforms (calculated pHi = 4.87) were found to be in agreement with mass spectrometry measurements. When compared to the sequence libraries, the Lom OMP, the first insect gonadotropic neurohormone, was revealed as an unique protein.

Amino Acid Sequence↗
PubMed1992

Isolation and structural determination of three peptides from the insect Locusta migratoria. Identification of a deoxyhexose-linked peptide.

We have isolated three novel peptides from the aqueous extract of the pars intercerebralis of male and female adults of the insect Locusta migratoria. After extensive HPLC purification, the peptides were characterised by automated Edman degradation and electrospray mass spectrometry: one is a 35-residue peptide (3752.3 +/- 1.1 Da) containing six cysteines involved in three intramolecular disulfide bridges, the second is a 36-residue peptide (3919.2 +/- 0.9 Da), also cross-linked by three intramolecular disulfide bridges. This second peptide is post-translationally modified by a single fucose moiety, which was identified by gas chromatography coupled to mass spectrometry. These two peptides show a strong sequence similarity. Additionally, they were also found in larger amounts in the fat body of Locusta; this finding raises the question of their exact site of synthesis. The third peptide (5776.3 +/- 0.9 Da), a 54-residue peptide cross-linked by six intramolecular disulfide bridges, is structurally related to the two other peptides, but to a lesser extent. Mass spectrometry has shown that all the cysteines within these three peptides are involved in intramolecular disulfide bridges; however, the location of these bridges is not yet established and is currently being investigated. A computer search of sequence data banks did not reveal any significant similarity of these three peptides with other known proteins.

Amino Acid Sequence↗
PubMed1992

Expression of a pheromone-binding protein in insect cells using a baculovirus vector.

A cDNA encoding a pheromone-binding protein from the male silkmoth Antheraea pernyi has been integrated into the genome of the Autographa californica multiple nuclear polyhydrosis virus such that the transcription was under the control of the strong polyhedrin promoter. Recombinant pheromone-binding protein was expressed in a baculovirus-infected insect cell line (Sf9) and secreted from the cells into the culture medium. Using a two-step protocol, recombinant pheromone-binding protein has been isolated and purified to homogeneity. Pheromone binding of recombinant protein has been demonstrated using a tritiated analog of (E,Z)-6,11-hexadecadienyl acetate.

Affinity Labels↗
PubMed1993

Efficient secretion of attacin from insect fat-body cells requires proper processing of the prosequence.

The attacins constitute a group of immune proteins induced after bacterial infection in the moth Hyalophora cecropia. They are synthesized as preproproteins and undergo post-translational modification during transport to the hemolymph. The processing and transport rates of attacin were studied in its natural host as a response to infection. Monensin totally inhibited the processing from proattacin to attacin and the radiolabeled proattacin remained intracellular. This observation indicated that the prosequence is removed at or after the trans-Golgi compartment. It is also suggested that the processing of the prosequence does not occur in acidic vesicles, as the process was not inhibited by the weak base chloroquine. To study prosequence function, the attacin gene and genes with mutations in the prosequence were cloned into the baculovirus Autographa californica nuclear polyhedrosis virus. The processing of proattacin and the transport of attacin were studied by pulse-chase experiments with fat body isolated from Trichoplusia ni larvae. The rate of secretion from fat body was lowest for proattacin, which could not be processed to attacin, intermediate for attacins lacking the prosequence and highest for natural attacin. We could not detect any biological activity for proattacin.

Amino Acid Sequence↗
PubMed1993

Molecular characterization of HES-2, a mammalian helix-loop-helix factor structurally related to Drosophila hairy and Enhancer of split.

Drosophila hairy (h) plays a crucial role in early development as a pair-rule segmentation gene. h and its structurally related gene Enhancer of split [E(spl)] are also required for normal sensory neurogenesis in late development. To analyze the molecular mechanisms of mammalian development, we recently characterized three rat helix-loop-helix (HLH) factors that show structural homology to the Drosophila h and E(spl) gene products, and found that rat factors exhibit distinct spatiotemporal expression patterns and act as a negative regulator. Here, we report the molecular characterization of another member of this family, designated HES-2. Rat HES-2 protein has a basic HLH domain homologous to h and E(spl) as well as the carboxy-terminal Trp-Arg-Pro-Trp sequence conserved among this family. The HES-2 mRNA is present as early as embryonic day 9.5 and is detected in a variety of tissues of both embryos and adults. DNase-I-footprinting analyses indicate that HES-2 binds to all E box sequences (CANNTG) we tested as well as to the N-box sequences (CACNAG). Further studies of gel-mobility-shift assays show that HES-2 has a higher affinity for the E box than for the N box. Transient transfection analyses suggest that HES-2 decreases the transcription originating from the promoters containing either the E box or the N box. These results indicate that HES-2 acts as a negative regulator through interaction with both E-box and N-box sequences.

3T3 Cells↗
PubMed1993

Combined plasma-desorption mass spectrometry and Edman degradation applied to simultaneous sequence determination of isoforms of structural proteins from the cuticle of Locusta migratoria.

The primary structures of two basic low-molecular-mass proteins, Lm-67 and Lm-70 from the pharate cuticle of the migratory locust, Locusta migratoria, were determined. The sequencing strategy was based on combined use of plasma--desorption mass spectrometry (PDMS) and automatic Edman degradation of the proteins and their enzymically derived peptides. The mass-spectral data showed the presence of two proteins in each preparation. For protein preparation Lm-67, this was indicated by the mass spectrum of the intact protein. For protein preparation Lm-70, the presence of two variants only became evident by mass-spectrometric analysis of the enzymically derived peptides. Both proteins show strong similarity to other exocuticular proteins from L. migratoria.

Amino Acid Sequence↗
PubMed1993

Solution conformation of an antibacterial peptide, sarcotoxin IA, as determined by 1H-NMR.

The solution conformation of sarcotoxin IA, which is an antibacterial peptide isolated from Sarcophaga peregrina with a molecular mass of 4 kDa, was determined by NMR spectroscopy and hybrid distance geometry/dynamical simulated annealing calculations. On the basis of 227 experimental constraints, including 185 distance constraints obtained from NOE and 42 constraints associated with 21 hydrogen bonds, a total of 18 converged structures of sarcotoxin IA were obtained. The final 18 converged structures exhibit backbone-atomic root-mean-square differences about the averaged coordinate positions of 0.070 +/- 0.027 nm for residues 3-23 and 0.040 +/- 0.017 nm for residues 28-38. It has been indicated that sarcotoxin IA consists of two amphiphilic alpha-helical regions, i.e. helix I (Leu3-Gln23) and helix II (Ala28-Ala38), with a hinge region (Gly24-Ile27), which connects helix I and helix II. We conclude that these two amphiphilic helical segments of sarcotoxin IA are of importance for the expression of the antibacterial activity.

Amino Acid Sequence↗
PubMed1996

Formation of pores in Escherichia coli cell membranes by a cecropin isolated from hemolymph of Heliothis virescens larvae.

The insect humoral defense system produces antibacterial peptides called cecropins. Cecropins were initially isolated from Hyalophora cecropia pupae and have since been isolated and identified in various insects. In this study, we have isolated and identified a cecropin from Heliothis virescens larvae. Rabbit IgG were raised against synthetic cecropin B. Affinity chromatography with the rabbit anti-(cecropin B) IgG was used to isolate a cecropin from hemolymph of H. virescens larvae. Acid gel electrophoresis followed by a bacterial-overlay analysis showed that Heliothis cecropin is a basic peptide of low molecular mass with bactericidal activity against Escherichia coli K12 D31. Heliothis cecropin is therefore analogous to synthetic cecropin B. One unresolved issue concerning cecropins and other antibiotic peptides is the mode of action by which they kill bacteria. By means of electron microscopy and immunocytochemistry with gold-labeled rabbit anti-cecropin IgG, binding of purified and synthetic cecropin to the cell membranes of E. coli K12 D31 cells was observed. Small lesions in the cell membrane were seen that had a diameter of 9.6 nm and internal pore of 4.2 nm. The Heliothis cecropin was found to be a pore-forming molecule that causes lesions in the cell membrane of E. coli K12 D31. The lesions lead to leakage of cytoplasmic contents and death of bacteria.

Animals↗
PubMed1996

Cyclosporin A inhibits the degradation of signal sequences after processing of presecretory proteins by signal peptidase.

Targeting of presecretory proteins to, and insertion into, the microsomal membrane are mediated by signal sequences. These signal sequences are removed from presecretory proteins by signal peptidase. We demonstrate that the signal sequence of preprolactin, after translocation into microsomes and cleavage by signal peptidase, is converted to an intermediate form. This intermediate was found outside the microsomes, where it was degraded in the presence of cytosol. Degradation of the signal sequence of another presecretory protein, preprocecropinA, occurred even in the absence of cytosol. The immunosuppressant cyclosporin A inhibited trimming of the preprolactin signal sequence and degradation of the preprocecropinA signal sequence. We observed by cross-linking studies that cleaved signal sequences are bound to two microsomal proteins prior to degradation.

Amino Acid Sequence↗
PubMed1997

Conservation of hexamerin endocytosis in Diptera.

In cyclorrhaphan Diptera at least two different types of haemolymph proteins exist which belong to the class of hexamerins. In the last larval instar of Calliphora vicina, the highly aromatic hexamerin, arylphorin, and the second hexamerin, PII, make up about 90% of haemolymph proteins. Both of these proteins are selectively taken up by the fat body cells at the end of larval life and share a common membrane-bound receptor. In addition, hexamerins and possible hexamerin receptors of Calliphora vicina, Calliphora vomitoria, Drosophila melanogaster, Ceratitis capitata, Sarcophaga bullata, Musca domestica and Protophormia terraenovae were investigated. Uptake of arylphorin by the larval fat bodies of Calliphora vicina as well asarylphorin-receptor binding can be competed in vitro by haemolymph from other Diptera. Therefore, hexamerin-receptor binding must be conserved among related cyclorrhaphan Diptera and between different types of hexamerins within a species. As the degree of competition is in good agreement with the presumed phylogenetic distances between these species, the method described here provides a simple tool to estimate evolutionary distances.

Animals↗
PubMed1997

Dromyosuppressin and drosulfakinin, two structurally related Drosophila neuropeptides, are uniquely expressed in the adult central nervous system.

Drosophila myosuppressin (TDVDHVFLRFamide; DMS) and sulfakinin (FDDYGHMRFamide; DSK) have similar C-terminal structures. To determine the neuronal expression patterns of these structurally related peptides, we have generated DMS- and DSK-specific antisera to multiple antigenic peptides and performed double-label immunochemistry with antisera raised on different animals of the same species host animal. Our data indicate that DMS and DSK staining patterns in the adult central nervous system are unique and nonoverlapping.

Amino Acid Sequence↗
PubMed2004

A draft sequence for the genome of the domesticated silkworm (Bombyx mori).

We report a draft sequence for the genome of the domesticated silkworm (Bombyx mori), covering 90.9% of all known silkworm genes. Our estimated gene count is 18,510, which exceeds the 13,379 genes reported for Drosophila melanogaster. Comparative analyses to fruitfly, mosquito, spider, and butterfly reveal both similarities and differences in gene content.

Algorithms↗
PubMed1994

Ability of cecropin B to penetrate the enterobacterial outer membrane.

The cationic amphipathic insect peptide cecropin B was almost as active on wild-type enteric bacteria as it was on their lipopolysaccharide and lipid A mutants that have very defective outer membrane. The polymyxin-resistant strains, which elaborate altered, less anionic lipopolysaccharide, were completely susceptible to cecropin B. No synergism was found between cecropin B and hydrophobic antibiotics. Throughout the study, the activity of cecropin B resembled that of quaternary detergents.

Cell Membrane Permeability↗
PubMed1989

Effects of magainins and cecropins on the sporogonic development of malaria parasites in mosquitoes.

Magainins and cecropins are families of peptides with broad antimicrobial and antiparasitic activities derived respectively from the skin of frogs or from giant silk moths. In insects, cecropins function as part of an inducible immune system against a number of bacterial infections. When injected into anopheline mosquitoes previously infected with a variety of Plasmodium species, both magainins and cecropins disrupt sporogonic development by aborting the normal development of oocysts; sporozoites are not formed and the vector cannot transmit the parasite to another host. It may be possible to induce effective transmission-blocking immunity in the mosquito vector by the introduction and expression of genes coding for magainins, cecropins, or similarly acting parasiticidal peptides into the mosquito genome.

Animals↗
PubMed1991

Attacin, an antibacterial protein from Hyalophora cecropia, inhibits synthesis of outer membrane proteins in Escherichia coli by interfering with omp gene transcription.

Attacins are antibacterial proteins synthesized by pupae of the giant silk moth, Hyalophora cecropia, in response to a bacterial infection. In this report we show that the previously described, attacin-induced alteration in the structure and the permeability of the outer membrane of Escherichia coli is associated with a specific inhibition of the synthesis of several outer membrane proteins, including OmpC, OmpF, OmpA, and LamB. The inhibition is expressed as a reduction in the steady-state mRNA levels and is at least in part the results of a block in transcription of the corresponding genes. Transcription directed by the promoter of ompR, the positive regulator of ompC and ompF expression in response to environmental conditions, is also affected by attacin. The effects on mutant strains show that the primary activity of attacin is not mediated by the ompR-envZ regulatory system. Instead our data suggest the existence in E. coli of a previously unknown system for the transcriptional regulation of a large set of outer membrane proteins previously not known to be coordinately regulated. We propose that the activity of attacin is directed towards this system.

Animals↗
PubMed1983

Escherichia coli mutants with an altered sensitivity to cecropin D.

Cecropins are a family of small, basic antibacterial polypeptides which can be isolated from pupae of immunized Lepidoptera. They are active against both gram-negative and gram-positive bacteria. We studied a mutant of Escherichia coli, strain SB1004, which is more sensitive to cecropin D than is the parental strain. The mutant was selected as resistant to a host range mutant of a Serratia marcescens phage. When the protein composition of the outer membrane was examined, strain SB1004 and some other phage-resistant mutants were found to be deficient in the OmpC protein. It was concluded that the OmpC protein is the receptor of the phage. Strain SB1004 was found to differ from other ompC mutants in being especially sensitive to hydrophobic antibiotics and to cecropin D. Furthermore, strain SB1004 has a tendency for spontaneous autolysis. A genetic analysis showed the mutations in strain SB1004 and a suppressor mutant to map in the ompC region. The activity of cecropin D against different strains of E. coli was specifically enhanced when divalent cations were absent. No such effect was found with cecropins A and B, which are less hydrophobic than the D form.

Animals↗