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PubMed1995

Molecular cloning of a widely expressed human homologue for the Drosophila trp gene.

The Drosophila transient receptor potential (trp) gene and its homologue, trpl, have been suggested to mediate calcium entry during the insect's phototransduction process. We isolated a human cDNA, human trp-1 (Htrp-1), encoding a polypeptide of 793 amino acids that is 37% identical (62% similar) to Drosophila trp and trpl. Northern analysis showed that the Htrp-1 transcript is approximately 5.5 kb and expressed in most human tissues, with higher amounts in ovary, testis, heart, and brain. Isolation of Htrp-1 suggests that a trp-type protein is present in mammals and should provide a useful tool in studying calcium-depletion induced calcium influx processes.

Amino Acid Sequence↗
PubMed1991

Isolation, primary structure, and synthesis of locustapyrokinin: a myotropic peptide of Locusta migratoria.

A neuropeptide which stimulates the motility of the cockroach hindgut has been isolated from an extract of 9000 brain-corpora cardiaca-corpora allata-subesophageal ganglion complexes of Locusta migratoria. Biological activity was monitored during HPLC purification by observing the myotropic effect of column fractions on the isolated hindgut of Leucophaea maderae. The primary structure of this myotropic peptide was established as a blocked 16-residue peptide: pGlu-Asp-Ser-Gly-Asp-Gly-Trp-Pro-Gln-Gln-Pro-Phe-Val-Pro-Arg-Leu-NH2. This novel locust peptide was designated as locustapyrokinin, or Lom-PK. Lom-PK was synthesized and shown to have chromatographic and biological properties identical to those of the native material. Lom-PK has a Phe-X-Pro-Arg-Leu-NH2 carboxy terminal in common with leucopyrokinin (or Lem-PK), a blocked myotropic neuropeptide isolated from the cockroach hindgut. The constituent amino acids of this C-terminal are important for biological activity on the Leucophaea hindgut. The primary structure of this novel insect peptide is, however, substantially different from Lem-PK at the amino-terminal sequence.

Amino Acid Sequence↗
PubMed1986

Gene within a gene: nested Drosophila genes encode unrelated proteins on opposite DNA strands.

A pupal cuticle protein gene has been found within an intron of a Drosophila gene that encodes three purine pathway enzymatic activities. The intronic gene is encoded on the DNA strand opposite the purine pathway gene and is itself interrupted by an intron. Whereas the purine pathway gene is active throughout development, the intronic cuticle protein gene is expressed primarily over a 3 hr period in the abdominal epidermal cells of prepupae that secrete the pupal cuticle. Therefore, a housekeeping gene and a developmentally regulated gene function in a nested arrangement.

Acyltransferases↗
PubMed1992

Molecular cloning and nucleic acid binding properties of the GAP-associated tyrosine phosphoprotein p62.

p62 is a tyrosine phosphoprotein that associates with p21ras GTPase-activating protein (GAP). Purification and cDNA cloning of p62 reveal extensive sequence similarity to a putative hnRNP protein, GRP33. Recombinant human p62 purified from insect Sf9 cells binds to DNA and to mRNA and, like many proteins involved in mRNA processing, recombinant p62 is modified by dimethylation on multiple arginine residues. p62 also binds tightly to p21ras GAP in vitro: this binding depends on phosphorylation of p62 on tyrosine residues and occurs through SH2 regions of GAP. These data suggest that p120-GAP and p62 play a role in some aspect of mRNA processing or utilization and that this role may be regulated by tyrosine phosphorylation, and indirectly, by p21ras.

3T3 Cells↗
PubMed1992

twine, a cdc25 homolog that functions in the male and female germline of Drosophila.

twine is the second homolog of the fission yeast gene cdc25 to be found in Drosophila. Both string and twine cDNAs can rescue a temperature-sensitive cdc25 mutation in fission yeast, but not a deletion. We detect the expression of string but not twine transcripts in the proliferating cells of newly cellularized embryos, in third instar larval brains, and in imaginal discs. Both genes are abundantly expressed in nurse cells during oogenesis, the maternal transcripts persisting throughout the syncytial stage of embryonic development. In the testis, twine transcripts are seen in the growing stage of premeiotic cysts. Analysis of a twine mutant suggests a requirement for the gene during oogenesis, during syncytial embryonic development, and for male meiosis. Meiosis does not occur in homozygous twine males, which produce cysts containing 16 rather than 64 spermatids.

Amino Acid Sequence↗
PubMed1994

Groucho is required for Drosophila neurogenesis, segmentation, and sex determination and interacts directly with hairy-related bHLH proteins.

We have used the interaction trap, a yeast two-hybrid system, to identify proteins interacting with hairy, a basic-helix-loop-helix (bHLH) protein that represses transcription during Drosophila embryonic segmentation. We find that the groucho (gro) protein binds specifically to hairy and also to hairy-related bHLH proteins encoded by deadpan and the Enhancer of split complex. The C-terminal WRPW motif present in all these bHLH proteins is essential for this interaction. We demonstrate that these associations reflect in vivo maternal requirements for gro during neurogenesis, segmentation, and sex determination, three processes regulated by the above bHLH proteins, and we propose that gro is a transcriptional corepressor recruited to specific target promoters by hairy-related bHLH proteins.

Animals↗
PubMed1994

The spätzle gene encodes a component of the extracellular signaling pathway establishing the dorsal-ventral pattern of the Drosophila embryo.

spätzle is a maternal effect gene required in the signal transduction pathway that establishes the dorsal-ventral pattern of the Drosophila embryo. spätzle acts immediately upstream of the membrane protein Toll in the genetic pathway, suggesting that spätzle could encode the ventrally localized ligand that activates the receptor activity of Toll. The spätzle gene encodes a novel secreted protein that appears to require activation by a proteolytic processing reaction, which is controlled by the genes that act upstream of spätzle in the genetic pathway. We propose that proteolytic processing of the spätzle protein is confined to the ventral side of the embryo and that the localization of processed spätzle determines where the receptor, Toll, is active.

Amino Acid Sequence↗
PubMed1995

Phosphoinositide-mediated phototransduction in Drosophila photoreceptors: the role of Ca2+ and trp.

Drosphoinate photoreceptors, represent a paradigm for the genetic dissection of phototransduction and, more generally for Ca2+ signaling. As in most invertebrates, phototransduction in Drosophila is mediated by the phosphoinositide (PI) cascade and is completely blocked by null mutations of the norpA gene which encodes a phospholipase C-beta isoform. The light-activated conductance in Drosophila is normally highly permeable to Ca2+, but in null mutants of the trp gene Ca2+ permeability is greatly reduced. Furthermore, the trp gene sequence shows homologies with voltage gated Ca2+ channels, suggesting that trp encodes a light-sensitive channel subunit. Ca2+ influx via these channels is instrumental in light adaptation, and profoundly influences phototransduction via positive and negative feedback at multiple molecular targets including protein kinase C. The mechanism of activation of the light-sensitive channels remains unresolved. A requirement for Ca2+ release from internal stores is suggested by the finding that Drosophila photoreceptors cannot sustain a maintained response under various conditions which might be expected to result in depletion of Ca2+ stores. However, Ca2+ release cannot be detected by Ca2+ indicator dyes and raising Ca2+ by photorelease of caged Ca2+ fails to mimic excitation. Recent studies, both in situ and with heterologously expressed trp protein, suggest that the trp-dependent channels may be activated by a process analogous to 'capacitative Ca2+ entry', a widespread, but poorly understood mode of PI-regulated Ca2+ influx in vertebrate cells.

Animals↗
PubMed1985

On the primary structures of lysozyme, cecropins and attacins from Hyalophora cecropia.

Diapausing pupae of Cecropia respond to a bacterial infection by the selective synthesis of RNA and 15-20 hemolymph proteins. Of these we have purified lysozyme and two classes of antibacterial proteins called cecropins and attacins. The primary structure has been determined for the lysozyme, one attacin and five cecropins. We have also prepared a cDNA bank, isolated and sequenced clones corresponding to the lysozyme, the two main attacins and one cecropin. The results of these structural studies are briefly summarized. Finally we review the solid phase synthesis of cecropin A and B and 9 analogs of cecropin A.

Amino Acid Sequence↗
PubMed1986

The humoral antibacterial response of Drosophila adults.

Hemolymph from a normal adult Drosophila melanogaster lacks factors that block the growth of Escherichia coli, but hemolymph from a fly previously inoculated with Enterobacter cloacae inhibits bacterial growth. Antibacterial activity appears within two hours after inoculation, and is still detectable sixty days later. Activity is potent, and can be detected in as little as a quarter of the hemolymph from a single inoculated male fly. After inoculation, at least eight new polypeptides not of bacterial origin appear in hemolymph with a time course similar to the appearance of antibacterial activity; these are called Antibacterial Response Polypeptides, or ARs. The most prominent polypeptides are AR24, AR22, and AR19 with molecular weights of about 24, 22, and 19 kilodaltons (kd). Other bands with as much as 75 kd and as little as 5 kd were also found. Electrophoresis of active hemolymph under non-denaturing conditions, and isoelectric focusing separate several protein species that block bacterial growth (Antibacterial Proteins, or ABs); one AB is neutral (AB7.1) and three are basic (AB8.7, AB9.0 and AB9.2). Two dimensional gels show that AR24, AR22 and AR19 have pIs identical to the basic antibacterial proteins. Radiolabelling experiments proved that the ARs were synthesized de novo after bacterial inoculation. ARs in six species of Drosophila showed fundamentally similar electrophoretic patterns.

Animals↗
PubMedDate not supplied

Expression of antimicrobial peptide genes after infection by parasitoid wasps in Drosophila.

We report here the use of a specific beta-galactosidase staining assay and Northern blotting technique to examine the expression of three genes encoding either antibacterial peptides (diptericin, cecropin A) or an antifungal peptide (drosomycin) in Drosophila following infection by larval and pupal parasitoids. The results show that the genes encoding these peptides are either not induced or minimally induced in wasp-infected hosts, but remain responsive and are induced upon microbial challenge. As the parasitoids elicit a cellular response, our data suggest that the antimicrobial responses are activated and/or regulated by mechanisms that are independent of those mediating cellular encapsulation.

Animals↗
PubMed1989

Effects of a purified cecropin D from a Chinese silk moth on growth, function and differentiation of murine hemopoietic cells.

The effects of cecropin D, a small basic peptide isolated from a Chinese oak silk moth, on the functions or differentiation of mammalian hemopoietic cells are described in the present paper. This peptide suppressed lectin-induced DNA synthesis of murine splenocytes in a dose-dependent manner without any significant cytotoxic effects. It also exhibited inhibitory effects on antibody production in lipopolysaccharide-stimulated lymphocytes and on colony formation of hemopoietic progenitor cells in plasma clots culture. These results indicate that cecropin D can regulate growth, function and differentiation of murine hemopoietic cells. The biological significance of this finding is discussed from the comparative immunological point of view.

Animals↗
PubMed1990

Locustatachykinin III and IV: two additional insect neuropeptides with homology to peptides of the vertebrate tachykinin family.

Two myotropic peptides termed locustatachykinin III and IV were isolated from 9000 brain-corpora cardiaca-corpora allata-suboesophageal ganglion extracts of the locust, Locusta migratoria. The primary structures of Lom-TK III and IV were established as amidated decapeptides: Ala-Pro-Gln-Ala-Gly-Phe-Tyr-Gly-Val-Arg-NH2 (Lom-TK III) and Ala-Pro-Ser-Leu-Gly-Phe-His-Gly-Val-Arg-NH2 (Lom-TK IV). The locustatachykinins were synthesized and shown to have chromatographic and biological properties identical with those of the native materials. They stimulate visceral muscle contractions of the oviduct and the foregut of Locusta migratoria and of the hindgut of Leucophaea maderae. Both peptides exhibit sequence homologies with the vertebrate tachykinins. Sequence similarity is greater with the fish and amphibian tachykinins (up to 40%) than with the mammalian tachykinins. In addition, the intestinal and oviducal myotropic activity of the locustatachykinins is analogous to that of vertebrate tachykinins. Both chemical and biological similarities of vertebrate and insect tachykinins substantiates the evidence for a long evolutionary history of the tachykinin peptide family.

Amino Acid Sequence↗
PubMed1991

Isolation, identification and synthesis of locustamyoinhibiting peptide (LOM-MIP), a novel biologically active neuropeptide from Locusta migratoria.

A novel peptide termed locustamyoinhibiting peptide (LOM-MIP) was isolated from brain-corpora cardiaca-corpora allata-suboesophageal ganglion extracts of the locust, Locusta migratoria. The primary structure of this nonapeptide has been determined Ala-Trp-Gln-Asp-Leu-Asn-Ala-Gly-Trp-NH2. LOM-MIP suppresses the spontaneous contractions of the hindgut and oviduct of Locusta migratoria and of the hindgut of Leucophaea maderae. This novel peptide is, however, structurally different from leucomyosuppressin, a hindgut suppressing peptide isolated from Leucophaea maderae heads. LOM-MIP has a Gly-TrpNH2 carboxy-terminal in common with APGWamide, a penis retractor muscle inhibiting peptide isolated from the snail, Lymnea stagnalis. In addition, it shows carboxy-terminal sequence similarities with locust AKH II which ends in AGWamide. No sequence similarities were found with other vertebrate or invertebrate peptides. Synthetic LOM-MIP showed biological as well as chemical characteristics indistinguishable from those of native LOM-MIP.

Amino Acid Sequence↗
PubMed1994

Partial identification, synthesis and immunolocalization of locustamyoinhibin, the third myoinhibiting neuropeptide isolated from Locusta migratoria.

A blocked neuropeptide that suppresses the motility of the cockroach hindgut has been isolated from an extract of 9000 brain-corpora cardiaca-corpora allata-suboesophageal ganglion complexes of Locusta migratoria. Biological activity was monitored during HPLC purification by observing the myoinhibiting activity of column fractions on the isolated hindgut of Leucophaea maderae. Due to the low amount of material left after deblocking, this myoinhibiting peptide--designated as locustamyoinhibin or Lom-MIH--could only be partially sequenced: pGlu-X-Tyr-X'-Lys-Gln-Ser-Ala-Phe-Asn-Ala-Val-Ser-NH2. Nevertheless, the carboxy-terminal nonamer sequence (Lom-MIH5-13) was synthesized and also displayed myoinhibiting activity, indicating that the biologically active core lies in the carboxy-terminal sequence. Lom-MIH shows no sequence similarities with other peptides from vertebrate or invertebrate sources and is the third myoinhibiting peptide identified in Locusta migratoria. A polyclonal antiserum was raised against Lom-MIH5-13 and used to investigate the distribution of immunoreactive peptide in the central nervous system and its associated neurohaemal structures. Two groups of neurons with somata in the optic lobes show locustamyoinhibin (Lom-MIH)-like immunoreactivity. These groups have somata at the dorsal and ventral edge of the lamina ganglionaris. The neurons have dense ramifications in the lamina, with processes extending into the first optic chiasma and into the accessory medulla. Four cell bodies were detected in the protocerebrum, and two cells were found at the externo-lateral edge of the tritocerebrum. No immunoreactive perikarya could be observed in the suboesophageal ganglion nor in the ganglia of the ventral nerve cord. Neither the corpora cardiaca nor the neurohaemal organs of the ventral nerve cord showed immunolabelling. Therefore, our findings provide anatomical evidence for a central neurotransmitter role of Lom-MIH.

Amino Acid Sequence↗
PubMed1995

The identification of two myoinhibitory peptides, with sequence similarities to the galanins, isolated from the ventral nerve cord of Manduca sexta.

Two new myoinhibitory peptides, Mas-MIP I and Mas-MIP II, were identified from the ventral nerve cord of the adult tobacco hornworm, Manduca sexta. Sequences obtained by a combination of automated Edman degradation and electrospray mass spectrometry were, respectively, AWQDLNSAW and GWQDLNSAW. The native peptides were found to co-elute with synthetic C-terminal amides on a reverse phase HPLC system. When applied to isolated ilea (anterior hindgut) of adult M. sexta, both peptides were found to significantly reduce the rate of peristalsis, or abolish peristalsis entirely, at concentrations of 1 x 10(-9) M. Both peptides share sequence similarities with Lom-MIP, a previously identified myoinhibitory peptide from Locusta migratoria, and with the N-terminal portion of vertebrate peptides in the galanin family.

Abdomen↗
PubMed1996

Isolation of five tachykinin-related peptides from the midgut of the cockroach Leucophaea maderae: existence of N-terminally extended isoforms.

Using a radioimmunoassay (RIA) with an antiserum to the locust neuropeptide locustatachykinin I (LomTK I) and a cockroach hindgut contraction bioassay as monitors, we isolated 5 tachykinin-related peptides from an acidic extract of 600 midguts of the cockroach Leucophaea maderae. A series of 4 different reversed-phase high performance liquid chromatography (rpHPLC) column systems were required to obtain pure peptides. The sequences of the 5 isolated myostimulatory and LomTK immunoreactive peptides were determined by Edman degradation. Four of these were confirmed by mass spectrometry and chemical synthesis as: APSGFLGVRamide, NGERAPGSKKAPSGFLGTRamide, APAMGFQGVRamide and APSGFMGMRamide. The fifth peptide, APEESPKRAPSGFLGVRamide, was confirmed only by mass spectrometry. These peptides, which were designated Leucophaea tachykinin-related peptides 1-5 (LemTRP 1-5), are structurally related to tachykinin-related peptides previously isolated from a locust, blowfly and mosquito species, but showed a somewhat larger variability in their amino-acid sequence (including the carboxy terminus). The two N-terminally extended forms contain putative cleavage sites (KR and KK, respectively) and such extended tachykinins have not been previously identified in insects. All 5 LemTRPs are myotropic and induce increases in the tonus and frequency of spontaneous contractions of hindgut muscle in L. maderae. The potency of the different synthetic isoforms is very similar; they all have a stimulus threshold concentration of 2.5 x 10(-10) M and an ED50 of about 10(-9) M. The synthetic peptides were tested in RIA and found to cross react to different degrees with the antiserum to LomTK I, but it is likely that in immunocytochemistry performed earlier, all 5 forms were detected in the midgut. It is, however, not clear which isoforms are located in endocrine cells and neural fibers of the midgut, respectively.

Amino Acid Sequence↗
PubMed1989

Stage-specific detection of a DNA-binding protein for the storage protein gene of Sarcophaga peregrina.

A nuclear extract of fat body prepared from third instar larvae of Sarcophaga peregrina (flesh fly) was found to contain a DNA-binding protein that specifically bound to 5'-upstream region of the storage protein (arylphorin) gene. This protein was found only in larvae harvested 46 h after larval emergence, indicating that its appearance was strictly regulated by the developmental stage of the insect. Since the storage protein gene is actively transcribed in the fat body at this stage, this protein is probably a specific transcription factor for the storage protein gene. DNase I footprinting analysis showed that the nucleotide sequence of the binding site of this protein is ACCACAACA, which is located at residues -247 to -255 upstream of the +1 site. Results indicated that formation of the DNA-protein complex required Zn2+.

Animals↗