Humoral immunity in Cecropia pupae.
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Amino Acid Sequence↗
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Isolation and characterization of a kettin-like protein from crayfish claw muscle.
A 540 kDa protein was isolated from crayfish claw muscle (closer). The secondary structure mainly consisted of beta-sheet (70%). The rotary shadowed images were long filaments, 300-360 nm long. It is localized in the sides of the Z-lines extending to the I band and elongatable upon stretch of muscle. Immunological crossreactivities strongly suggested that this protein corresponds to kettin (500-700 kDa) of insect striated muscle. In view of molecular shape and secondary structure, and immunological crossreactivities, it is suggested that this kettin-like protein belongs to connectin/titin family of striated muscle.
Actins↗
A new member of the balbiani ring multigene family in the dipteran Chironomus tentans consists of a single-copy version of a unit repeated in other gene family members.
The known Balbiani ring (BR) multigene family members in the dipteran Chironomus tentans encode salivary gland secretory proteins in the size range between 38 and 1,000 kDa. The proteins interact to form protein fibers used by the aquatic larvae to spin feeding and protective larval tubes or pupation tubes. Here, we describe a new BR multigene family member, the sp17 gene, which codes for an 89-amino-acid-long protein with a relative mobility of 17k. The gene has a high content of charged amino acid residues and consists of two structurally different halves. Five regularly spaced cysteine codons are present in the 5' half while the 3' half contains five proline codons. These two different halves exhibit similarities to the C and SR regions, respectively, which form the tandemly repeated units in the about 40-kb-long BR genes and which also, in different versions, are the building blocks of all genes in the BR multigene family. In this multigene family, encoding interacting structural proteins, the long BR genes with their 125-150 tandemly arranged repeat units as well as the short sp17 gene with its single-copy version of such a repeat unit, have therefore evolved from a common ancestor.
Amino Acid Sequence↗
Conserved and variable repeat structures in the Balbiani ring gene family in Chironomus tentans.
The four Balbiani ring (BR) genes, BR1, BR2.1, BR2.2, and BR6 in the midge Chironomus tentans constitute a gene family encoding secretory proteins with molecular weights of approximately 10(6) daltons. The major part of each gene is known to consist of tandemly organized composite repeat units resulting in a hierarchic repeat arrangement. Here, we present the sequence organization of the 5' part of the BR2.2 and BR6 genes and describe the entire transcribed part of the two genes. As the BR1 and BR2.1 genes were also fully characterized recently, this allows the comparison of all genes in the BR gene family. All four genes share the same exon-intron structure and have evolved by gene duplications starting from a common ancestor, having the same overall organization as the BR genes of today. The genes encode proteins that have an approximately 10,000-amino acid residue extended central domain, flanked by a highly charged, approximately 200-residue amino-terminal domain and a globular 110-residue carboxy-terminal domain. Exons 1-3 and the beginning of exon 4 encode the amino-terminal domain, which throughout contains many regions built from short repeats. These repeats are often degenerate as to repeat unit and sequence and are present in different numbers between the genes. In several instances these repeat structures, however, are conserved at the protein level where they form positively or negatively charged regions. Each BR gene has a 26-38-kb-long exon 4, which consists of an array of 125-150 repeat units and encodes the central domain. The number of repeat units appears to be largely preserved by selection and all repeat units in the array are very efficiently homogenized. Occasionally variant repeats have been introduced, presumably from another BR gene by gene conversion, and spread within the array. Introns 1-3 at the 5' end of the genes have diverged extensively in sequence and length between the genes. In contrast, intron 4 at the 3' end is virtually identical between three of the four genes, suggesting that gene conversion homogenizes the 3' ends of the genes, but not the 5' ends.
Amino Acid Sequence↗
Primary structure of a pheromone-binding protein from Antheraea pernyi: homologies with other ligand-carrying proteins.
An antennal cDNA clone encoding the complete sequence (163 amino acids) of a pheromone-binding protein precursor from the male silk moth, Antheraea pernyi, was isolated using oligonucleotide probes. The cloned cDNA was expressed and the translation product detected by specific antibodies. The deduced protein sequence consists of a signal peptide of 21 amino acids and a mature binding protein of 142 amino acid residues. The predicted structure of this protein is homologous to binding-proteins from different insect species which have previously been identified, but shows no similarities to odorant-binding proteins from vertebrates, suggesting that soluble odorant-binding proteins in insects and vertebrates represent an evolutionary convergence.
Amino Acid Sequence↗
Restricted occurrence of Locusta migratoria ovary maturing parsin in the brain-corpora cardiaca complex of various insect species.
Ovary maturing parsin (OMP) is a gonadotrophic molecule previously isolated from the neurosecretory lobes of the corpora cardiaca of Locusta migratoria (acridian Orthoptera). A polyclonal antiserum directed against the two biologically active domains of the L. migratoria (Lom) OMP was used to investigate the occurrence of Lom OMP-like substances in brain-corpora cardiaca complexes of other insect species. Using immunohistochemistry, specimens of 40 different insect species belonging to 13 insect orders were tested. The Lom OMP-like substance was strictly limited to specimens of insect species belonging to the Acridae. It occurred in non-basophilic cells of the pars intercerebralis that project to the corpora cardiaca, as in Locusta. Although the antiserum only detected Lom OMP-like material in the Acridae, it is possible that related molecules exist in other insects. The antiserum may be very specific for domains of the Lom OMP molecule that have not been highly conserved during evolution or possibly these domains are not accessible to the antiserum in other insects.
Animals↗
Quaternary and subunit structure of Calliphora arylphorin as deduced from electron microscopy, electrophoresis, and sequence similarities with arthropod hemocyanin.
Arylphorin was purified from larvae of the blowfly Calliphora vicina and studied in its oligomeric form and after dissociation at pH 9.6 into native subunits. In accordance with earlier literature, it was electrophoretically shown to be a 500 kDa hexamer (1 x 6) consisting of 78 kDa polypeptides (= subunits). Electron micrographs of negatively stained hexamers show a characteristic curvilinear, equilateral triangle of 12 nm in diameter (top view) and a rectangle measuring 10 x 12 nm (side view). Alternatively, particles in the top view orientation exhibit a roughly circular shape 12 nm in diameter. Crossed immunoelectrophoresis revealed the presence of a major subunit type; the nature of a very minor and a third immunologically separated component remains unclear. A novel 2 x 6 arylphorin particle was detected and isolated. It comprises less than 10% of the total arylphorin material and shows a long, narrow interhexamer bridge in the electron microscope. An arylphorin dissociation intermediate identified as a trimer (1/2 x 6) was isolated; its possible quaternary structure is discussed on the basis of electron micrographs. The epitope of monoclonal antibody Ec-7 directed against tarantula (Eurypelma californicum) hemocyanin subunit d and also reactive to Calliphora arylphorin was traced to a highly conserved peptide of 27 amino acids localized in the center of the protein. The primary structure of Calliphora arylphorin as published in our preceding paper (Naumann and Scheller 1991) is compared in detail to the sequences of spider and spiny lobster hemocyanin. This revealed a basic framework of 103 strictly conserved amino acids. Isofunctional exchanges are proposed for another 76 positions. On the basis of these similarities, and the published three-dimensional model of spiny lobster hemocyanin, a detailed model of the quaternary structure of Calliphora arylphorin is presented. A second larval storage protein previously termed protein II was purified from Calliphora hemolymph. It was demonstrated to be a 500 kDa hexamer of 83 kDa subunits. In the electron microscope it shows a cubic view 9 nm in length with a large central hole and a rectangular view (9 x 10 nm) with a large central cavity. A morphologically very similar hemolymph protein was detected in Drosophila melanogaster larvae. From its structural appearance it is uncertain whether protein II belongs to the hemocyanin superfamily or not.
Amino Acid Sequence↗
Insect myotropic peptides: differential distribution of locustatachykinin- and leucokinin-like immunoreactive neurons in the locust brain.
Locustatachykinin I is one of four closely related myotropic neuropeptides isolated from brain and corpora-cardiaca complexes of the locust Locusta migratoria. Antiserum was raised against locustatachykinin I for use in immunocytochemistry. It was found that the antiserum recognizes also locustatachykinin II and hence probably also the other two locustatachykinins due to their similarities in primary structure. Locustatachykinin-like immunoreactive (LomTK-LI) neurons were mapped in the brain of the locust, L. migratoria. A total of approximately 800 LomTK-LI neurons were found with cell bodies distributed in the proto-, deuto- and tritocerebrum, in the optic lobes and in the frontal ganglion. Processes of these neurons innervate most of the synaptic neuropils of the brain and optic lobes, as well as the frontal ganglion and hypocerebral ganglion. The widespread distribution of LomTK-LI neurons in the locust brain indicates an important role of the locustatachykinins in signal transfer or regulation thereof. As a comparison neurons were mapped with an antiserum against the cockroach myotropic peptide leucokinin I. This antiserum, which probably recognizes the native peptide locustakinin, labels a population of about 140 neurons distinct from the LomTK-LI neurons (no colocalized immunoreactivity). These neurons have cell bodies that are distributed in the proto- and tritocerebrum and in the optic lobe. The processes of the leucokinin-like immunoreactive (LK-LI) neurons do not invade as large areas in neuropil as the LomTK-LI neurons do and some neuropils, e.g. the mushroom bodies, totally lack innervation by LK-LI fibers. In some regions, however, the processes of the LomTK-LI and LK-LI neurons are superimposed: most notably in the central body and optic lobes. A functional relation between the two types of neuropeptide in the locust brain can, however, not be inferred from the present findings.
Amino Acid Sequence↗
The suppressor of Hairy-wing binding region is required for gypsy mutagenesis.
We undertook a deletional analysis of the gypsy retrotransposon in order to determine which sequences of the element are required for its mutagenic effect. We show that a phenotype indistinguishable from that of y2 flies can be generated by transforming y- flies with a construct containing the yellow gene and a gypsy element located at the same insertion site in yellow as found in y2 flies. When flies are transformed with similar constructs in which increasing amounts of the 5' transcribed untranslated region of gypsy have been removed, either a partial y2 revertant or a completely revertant phenotype is obtained. These results yield direct proof that the region of gypsy to which the su(Hw) protein binds is required for the generation of mutant phenotypes by this retrotransposon.
Amino Acid Sequence↗
Genetic control and expression of the major ejaculatory bulb protein (PEB-me) in Drosophila melanogaster.
PEB-me is a predominant protein of mature Drosophila melanogaster ejaculatory bulbs. It is resolved into four or five closely spaced subfractions (apparent molecular weight 35-39 kD) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Four electrophoretic variants of PEB-me differing in apparent molecular weight by 200-800 daltons were found. These appear to be controlled by four alleles of a gene (peb) located by recombination and deletion mapping to the 60F1-2 region of chromosome 2. A minor ejaculatory bulb protein of ca. 80 kD (hPEB) was found to be immunochemically related to PEB and possibly encoded by peb. PEB is not detected by immunoblotting techniques in virgin females, in male tissues other than the ejaculatory bulb, or during developmental stages preceding the formation of this organ. The results of transplantations of genital imaginal discs and of immature ejaculatory bulbs between two strains having different PEB alleles suggest that the ejaculatory bulb is the site of PEB synthesis. In flies mutant for tra, tra-2, dsx, or ix, tissue specificity of PEB localization is retained and the protein is found whenever the ejaculatory bulb is formed, regardless of the chromosomal sex of the fly. The protein is transferred into the female genital duct during mating, where it can be detected for up to 12 hr. Possible functions of PEB in Drosophila reproduction are discussed.
Alleles↗
Synthesis of bombyxin-IV, an insulin superfamily peptide from the silkworm, Bombyx mori, by stepwise and selective formation of three disulfide bridges.
We report the synthesis of bombyxin-IV, a disulfide-linked, heterodimeric, insulin superfamily peptide from the silkworm, Bombyx mori. The two chains (A- and B-chains) were synthesized separately by the solid-phase method using fluoren-9-ylmethoxycarbonyl (Fmoc) group as a protecting group for alpha-amino group. Three disulfide bonds were bridged step by step (A6-A11, A20-B22, and A7-B10) in a good yield. Synthetic bombyxin-IV was identical with natural one with regard to the retention time on a reversed-phase column and the molecular weight measured by mass spectrometry. Circular dichroism (CD) spectrum of the synthetic bombyxin-IV was very similar to that of the natural one. The specific activity of synthetic bombyxin-IV is equal to that of natural one (0.1 ng/Samia unit). These results suggest that the synthetic bombyxin-IV has the tertiary structure identical with the natural peptide. Our method developed for synthesis of bombyxin-IV would be generally applicable to the synthesis of insulin-like heterodimeric peptides.
Amino Acid Sequence↗
Determination of disulfide bond arrangement in bombyxin-IV, an insulin superfamily peptide from the silkworm, Bombyx mori, by combination of thermolysin digestion of natural peptide and selective synthesis of disulfide bond isomers.
The mode of disulfide linkages in bombyxin-IV, an insulin superfamily peptide consisting of A- and B-chains, was determined as A6-A11, A7-B10, and A20-B22. An intermolecular bond of A20-B22 was identified by sequencing and mass spectrometric analysis of the fragments generated by thermolysin digestion of natural bombyxin-IV. The mode of the remaining two bridges was determined by chemical and selective synthesis of three possible disulfide bond isomers of bombyxin-IV. A- and B-chains were synthesized by solid-phase method, and three disulfide bonds were bridged stepwise and in a fully controlled manner. Retention time on reversed-phase high-performance liquid chromatography (HPLC), thermolysin digests, and biological activity of the synthetic [A6-A11, A7-B10, A20-B22-cystine]-bombyxin-IV revealed that it was identical with the natural bombyxin-IV. Two other isomers with respect to disulfide bond arrangement, [A6-A7, A11-B10, A20-B22-cystine]- and [A6-B10, A7-A11, A20-B22-cystine]-bombyxin-IVs, were distinguishable from the natural one by use of HPLC, thermolysin digestion, and bioassay.
Amino Acid Sequence↗
Immunogold detection of two neurohormones: the locust ovary maturing parsin and neuroparsin.
The cellular localization of two neurohormones of the locust pars intercerebralis-corpora cardiaca system: the ovary maturing parsin and neuroparsin, was investigated using electron microscopic immunocytochemistry (post-embedding immunogold labelling). The ovary maturing parsin and neuroparsin containing cells were first identified in semithin sections treated by combined histochemical- and immunostaining. The neuroparsin cells were paraldehyde fuchsin positive (A-type cells) and the ovary maturing parsin cells were paraldehyde fuchsin negative when semithin sections were stained with paraldehyde fuchsin and immunostained with anti-ovary maturing parsin serum. The ovary maturing parsin and neuroparsin producing cells were identified on immunogold labelled ultrathin sections adjacent to double stained semithin sections. Ovary maturing parsin cells have larger more numerous vesicles of greater electron density than neuroparsin cells. The neuroparsin cells contained more lysosomal structures than the ovary maturing parsin cells suggesting different neurosecretory dynamics. Thus, immunogold labelling with antisera specific for each neurohormone demonstrates the individual nature of these two neurosecretory cells in the pars intercerebralis of the Locust.
Animals↗
Diterpene acids as larval growth inhibitors.
Kaurenoic and trachylobanoic acids from sunflower inhibited larval development in several Lepidoptera species. The tricyclic resin acids were also effective in curtailing growth of Pectinophora gossypiella and either reduction to carbinol or esterification of the carboxyl group lowered activity. Partial reversal of growth inhibition in the presence of relatively large amounts of cholesterol suggests an interaction with the insects' hormonal system.
Animals↗
Expression of giant silkmoth cecropin B genes in tobacco.
Cecropin B is a small antibacterial peptide from the giant silkmoth Hyalophora cecropia. To reveal the potential of this peptide for engineering bacterial disease resistance into crops, several cecropin B gene constructs were made either for expression in the cytosol or for secretion. All constructs were cloned in a plant expression vector and introduced in tobacco via Agrobacterium tumefaciens. A cDNA-derived cecropin B gene construct lacking the amino-terminal signal peptide was poorly expressed in transgenic plants at the mRNA level, whereas plants harbouring a full-length cDNA-derived construct containing the insect signal peptide, showed increased cecropin B-mRNA levels. Highest expression was found in plants harbouring a construct with a plant-gene-derived signal peptide. In none of the transgenic plants could the cecropin B peptide be detected. This is most likely caused by breakdown of the peptide by plant endogenous proteases, since a chemically synthesized cecropin B peptide was degraded within seconds in various plant cell extracts. This degradation could be prevented by the addition of specific protease inhibitors and by boiling the extract prior to adding the peptide. In addition, anionic detergents, in contrast to cationic, zwitter-ionic or non-ionic detergents, could prevent this degradation. Nevertheless, transgenic tobacco plants were evaluated for resistance to Pseudomonas solanacearum, the causal agent of bacterial wilt of many crops, and P. syringae pv. tabaci, the causal agent of bacterial wildfire, which are highly susceptible to cecropin B in vitro. No resistance was found. These experiments indicate that introduction and expression of cecropin B genes in tobacco does not result in detectable cecropin B protein levels and resistance to bacterial infections, most likely due to degradation of the protein by endogenous proteases.
Amino Acid Sequence↗
Brain factor from Galleria mellonella (Lepidoptera) stimulating silk gland activity.
Brain extracts from day 1-4 last instar larvae of Galleria mellonella (Lepidoptera) stimulate RNA synthesis in cultured silk glands from day 3 last instar larvae. When the fibroin-synthesizing posterior parts of silk glands were incubated for 3 h in vitro in the presence of brain extract (0.1 brain equivalent), [3H]-uridine incorporation into RNA was stimulated more than twofold. The stimulating effect of brain extract showed a dose response relationship. It is suggested that the heat-resistant and protease-sensitive brain factor is a peptide.
Animals↗
Common origin of arthropod tyrosinase, arthropod hemocyanin, insect hexamerin, and dipteran arylphorin receptor.
Dipteran arylphorin receptors, insect hexamerins, cheliceratan and crustacean hemocyanins, and crustacean and insect tyrosinases display significant sequence similarities. We have undertaken a systematic comparison of primary and secondary structures of these proteins. On the basis of multiple sequence alignments the phylogeny of these proteins was investigated. Hexamerin subunits, hemocyanin subunits, and tyrosinases share extensive similarities throughout the entire amino acid sequence. Our studies suggest the origin of arthropod hemocyanins from ancient tyrosinase-like proteins. Insect hexamerins likely evolved from hemocyanins of ancient crustaceans, supporting the proposed sister-group position of these subphyla. Arylphorin receptors, responsible for incorporation of hexamerins into the larval fat body of diptera, are related to hexamerins, hemocyanins, and tyrosinase. The receptor sequences display extensive similarities to the first and third domains of hemocyanins and hexamerins. In the middle region only limited amino acid conservation was observed. Elements important for hexamer formation are deleted in the receptors. Phylogenetic analysis indicated that dipteran arylphorin receptors diverged from ancient hexamerins, probably early in insect evolution.
Amino Acid Sequence↗
The novel antibacterial peptide ceratotoxin A alters permeability of the inner and outer membrane of Escherichia coli K-12.
Ceratotoxins are antibacterial 3-kDa amphiphilic peptides isolated from the female reproductive apparatus of the medfly Ceratitis capitata. The antibacterial activity of a chemically synthesized ceratotoxin A (ctx A) has been investigated. Ctx A was mainly active against Gram-negative organisms, and it had a lytic effect on nongrowing Escherichia coli K-12. Data showed that ctx A alters both the outer and the inner membrane of E.coli K-12 cells.
Animals↗