Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “SILKWORMS”

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 379 records · Page 21Linked to original sources
PubMed1995

DNA fingerprinting in silkworm Bombyx mori using banded krait minor satellite DNA-derived probe.

The genomic DNA from thirteen different ecotypes and inbred lines of silkworm, Bombyx mori, were analyzed by digesting with BstNI and HinfI restriction enzymes followed by hybridization with banded krait minor satellite DNA (Bkm)-2(8) minisatellite probe. The DNA fingerprinting revealed 9-31 discrete intense bands, some of which were ecotype/inbred line-specific. Individual specific DNA fingerprints in two representative genotypes and their F1 hybrid offspring were also obtained. Individuals of a given parental line showed very similar profiles and the hybrid offspring showed the combined profile of both parents. The presence of bands specific to diapausing and nondiapausing strains and to particular genotypes indicate their potential use for marker-assisted breeding and varietal identification.

Animals↗
PubMed2003

Stage-dependent effects of 20-hydroxyecdysone on DNA synthesis of corpus allatum cells in the silkworm, Bombyx mori.

DNA synthesis in cells of the corpus allata (CA) of the silkworm, Bombyx mori, was studied immunocytochemically after in vivo labeling with 5-bromo-2'-deoxyuridine (BrdU); developmental changes during the 3rd, 4th, and last larval instars and effects of 20-hydroxyecdysone treatment were examined. During both the 3rd and 4th larval instars, the number of DNA-synthesizing cells fluctuated, and relatively low levels were observed during the middle stages. On day 0 of the last larval instar, the number of DNA-synthesizing cells per gland was 9.2, which then increased on day 1 and remained at levels ranging from 12.9 and 16.9 cells per gland. A major peak level (28 BrdU-labeled cells per gland) occurred on day 8, two days after larvae entered the wandering stage. When last instar larvae were fed 20-hydroxyecdysone-supplemented mulberry leaves starting on day 0 or 1, the number of DNA-synthesizing cells dramatically decreased to very low levels and these low levels were maintained throughout the remainder of the instar. However, no effect was observed when last instar larvae were fed 20-hydroxyecdysone-supplemented mulberry leaves starting on day 3, indicating the stage-specific action of 20-hydroxyecdysone. The mechanism by which 20-hydroxyecdysone treatment inhibits DNA synthesis of CA cells was further examined by using continuous in vitro BrdU labeling for a 2-day incubation. It was found that the decrease in responsiveness of DNA synthesis of CA cells of 20-hydroxyecdysone-treated larvae to stimulation by growth factors from hemolymph may have been, at least in part, responsible for the indirect inhibitory effects of 20-hydroxyecdysone.

Animals↗
PubMed2005

Regulation of capacitative Ca2+ entry by prothoracicotropic hormone in the prothoracic glands of the silkworm, Bombyx mori.

Measurements of Ca2+ influx in Fura-2/AM loaded steroidogenic cells (prothoracic glands; PGs) of the silkworm, Bombyx mori showed that application of the neuropeptide prothoracicotropic hormone (PTTH) can increase the intracellular [Ca2+]i. This PTTH-mediated Ca2+ influx in PG cells had kinetic patterns and pharmacological characteristics similar to those induced by thapsigargin. Namely, it produced increases in intracellular Ca2+ levels only in the presence of extracellular Ca2+, it was blocked by Gd3+ and 2-Aminoethoxydiphenylborate (2-APB), and it was unaffected by several toxins or compounds that block voltage-activated Ca2+ channels. Moreover, the PTTH-stimulated increase of Ca2+ levels was eliminated in the presence of heparin (an IP3 receptor blocker), and by TMB-8 which also blocked any PTTH-dependent increase of ecdysteroid secretion. The PTTH-mediated increase of Ca2+ levels was not affected by the non-hydrolysable GDP analogue, GDPbetaS, an indication that a G protein is not downstream of the PTTH receptor. These results argue strongly in favor of gating by the PTTH receptor of capacitative Ca2+ entry (CCE) channels (or store-operated Ca2+ channels (SOCs)) by a mechanism that does not involve any G proteins but requires the presence of functional IP3 receptors. Because the ability of PTTH to stimulate the [Ca2+]i levels of PG cells was completely mimicked by thapsigargin and exhibited a pharmacological profile similar to CCE mechanisms, we believe that PTTH directly regulates a CCE pathway in PG cells thereby activating a plethora of downstream regulators responsible for ecdysteroid secretion by the PGs of Bombyx mori.

Animals↗
PubMed2005

Temporal changes in DNA synthesis of prothoracic gland cells during larval development and their correlation with ecdysteroidogenic activity in the silkworm, Bombyx mori.

DNA synthesis in prothoracic gland cells of the silkworm, Bombyx mori, was studied immunocytochemically after in vivo labeling with 5-bromo-2'-deoxyuridine (BrdU), and its developmental changes during the 3rd, 4th, and last larval instars were examined. During the early stages of both the 3rd and 4th larval instars, a dramatic increase in the number of DNA-synthesizing cells of the prothoracic glands was detected. However, during the latter stages of each instar, the number of DNA-synthesizing cells greatly decreased. The determination of glandular protein content showed that dramatic increases occurred during the latter stages of each larval instar. Comparison of changes in prothoracic gland cell DNA synthesis with ecdysteroidogenic activity showed that the increase in DNA synthesis precedes ecdysteroidogenesis. The cellular mechanism underlying changes in prothoracic gland cell DNA synthesis during the last two larval instars was further analyzed by determining the in vitro DNA synthesis of the glands, their responsiveness to hemolymph growth factors, and changes in the growth-promoting activity of hemolymph during development. It was found that both growth factors and the responsiveness of the prothoracic gland cells to growth factors from hemolymph may play roles in regulating DNA synthesis of gland cells.

Animals↗
PubMed2001

Role of interaction between two silkworm RecA homologs in homologous DNA pairing.

Recombinant BmRad51 and BmDmc1, silkworm homologs of the Escherichia coli RecA proteins catalyzing the homologous DNA pairing, were purified from E. coli cells carrying expression vectors. These possessed different enzymatic properties in the joint molecule formation between single-stranded circular DNA and homologous linear double-stranded DNA. The requirement of single-stranded circular DNA for the efficient reaction was twofold higher in BmRad51 than in BmDmc1. Although able to mediate the joint molecule formation independently, a complex of the two enzymes formed prior to single-stranded DNA binding was found to have augmented efficiency of the pairing reaction.

Animals↗
PubMed1995

Occurrence of novel types of nitric oxide synthase in the silkworm, Bombyx mori.

Nitric oxide (NO) synthase activity was detected in fat body and the Malpighian tubles of the silkworm, Bombyx mori. Main NO synthase activity in the fat body was Ca(2+)/calmodulin-dependent, inducible by bacterial lipopolysaccharide (LPS) and required NADPH, FAD, FMN, dithiothreitol (DTT) and tetrahydrobiopterin (BH4) as cofactors for the full expression of the activity. The Malpighian tubles contained two types of NO synthase. One was Ca(2+)-independent, calmodulin-dependent and constitutive and the other was Ca(2+)-dependent and constitutive. The former NO synthase required the same cofactors as fat body NO synthase. The activity of Malpighian tuble NO synthases increased dramatically at the end of the last instar period, just prior to spinning. These results indicate that B. mori contains new types of NO synthase, suggesting the wide distribution and different characteristics of this enzyme among vertebrates and invertebrates.

Amino Acid Oxidoreductases↗
PubMed1996

Nucleotide sequence of 5'-upstream region and expression of a silkworm gene encoding a new member of the attacin family.

A genomic clone encoding a new member of attacin, an insect antibacterial protein, was isolated from a genomic library of the silkworm, Bombyx mori, and the nucleotide sequence of the 5'-upstream region was determined. The region contained Bm 1, a highly repetitive element of B. mori and a lipopolysaccharide (LPS) response element (RE)(NF-kappaB binding site), CAAT box and TATA box. Northern blot analysis showed that the attacin gene expression was rapidly induced by bacterial cell wall components such as LPS from Escherichia coli and peptidoglycan (PG) from Micrococcus luteus, suggesting that attacin plays an important role in an early phase of the self-defense system upon bacterial infection.

Animals↗
PubMed1996

Production in Escherichia of moricin, a novel type antibacterial peptide from the silkworm, Bombyx mori.

Moricin is a novel type antibacterial peptide recently isolated from the silkworm, Bombyx mori. Two foreign gene expression systems in Escherichia coli were employed to obtain a large amount of the peptide for further characterization. An artificial moricin gene was chemically synthesized and inserted into two expression vectors, pXa1 and pMAL-c2. The recombinant moricin was efficiently produced in E. coli as fusion proteins and released by chemical cleavage with cyanogen bromide or o-iodosobenzoic acid. Eleven milligrams of pure recombinant moricin was obtained from 2 L of E. coli culture. The primary structure and molecular mass of the purified recombinant moricin was the same as those of the natural moricin. In addition, the antibacterial activity of the recombinant moricin against E. coli and Staphylococcus aureus was comparable to that of the natural moricin.

Amino Acid Sequence↗
PubMed1996

Elicitors triggering the simultaneous gene expression of antibacterial proteins of the silkworm, Bombyx mori.

Various elicitors were examined by Northern blot analysis to investigate the simultaneous induction of gene expression of antibacterial proteins such as cecropin B, attacin and lebocin from the silkworm, Bombyx mori. Lipopolysaccharide (LPS), lipid A, 2-keto-3-deoxyoctonate (KDO) and peptidoglycan (PG) triggered efficiently and simultaneously the gene expression of antibacterial proteins. Effects of inhibitors for signal transduction on the gene expression of Bombyx mori (Bm) cecropin B triggered by lipid A were observed using isolated adherent hemocytes consisting of granular cells and plasma cells. H-7, H-89 but not W-7 inhibited gene expression, suggesting that protein kinase C and A but not myosine light chain kinase may participate in signal transduction.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

Identification of ecdysis-triggering hormone in the silkworm Bombyx mori.

Ecdysis, the shedding of cuticle at the end of each life stage, is critical to the postembryonic development of insects. The endocrine regulation of ecdysis has been highlighted by the recent description of the epitracheal endocrine system in the tobacco hornworm Manduca sexta, which produces ecdysis-triggering hormone (Mas-ETH). This peptide hormone initiates pre-ecdysis and ecdysis through a direct action on the central nervous system. Here we show that ETH-immunoreactivity and ecdysis-triggering activity in epitracheal glands of the silkworm Bombyx mori are attributable to a 23 amino acid peptide, Bom-ETH. The complete amino acid sequence of Bom-ETH is SNEAFDEDVMGYVIKSNKNIPRM-NH2. Synthetic Bom-ETH was prepared and shown to be chemically and biologically identical to the native substance. Injection of Bom-ETH leads to pre-ecdysis and ecdysis in B. mori pharate larvae and pupae as well as comparable stages of M. sexta. Exposure of the isolated nervous system to Bom-ETH triggers pre-ecdysis and ecdysis burst patterns corresponding to the natural behavior. Bom-ETH belongs to an extended family of multifunctional neurohormones and hormones found in arthropods and molluscs.

Amino Acid Sequence↗
PubMed1997

In vitro phagocytosis of Escherichia coli and release of lipopolysaccharide by adhering hemocytes of the silkworm, Bombyx mori.

A primary culture containing adhering hemocytes mainly granular cells from the silkworm, Bombyx mori, was used to investigate in vitro phagocytosis of Escherichia coli. Phagocytosis was confirmed to occur in this system by microscopic observation. Lipopolysaccharide (LPS) concentration in the culture medium was measured by a Limulus test and a higher LPS concentration was detected in phagocytosis-occurred samples than in control samples, which omitted either E. coli cells or adhering hemocytes. Moreover, it was found that LPS containing sample but not control samples strongly induces gene expression of cecropin B, an antibacterial protein. These results suggest that bacterial cell wall components like LPS released by phagocytosis play an important role in the induction of insect antibacterial proteins.

Animals↗
PubMed1997

A novel member of lebocin gene family from the silkworm, Bombyx mori.

We screened genomic clones encoding lebocin, an antibacterial peptide from the silkworm, Bombyx mori. Two positive clones were obtained and their nucleotide sequences indicated that they contain no introns. The deduced amino acid sequences revealed that one clone (Leb 3) encoded lebocin 3 and another (Leb 4) is a new member of the lebocin gene family. Gene expression of both Leb 3 and Leb 4 was shown to be induced by lipopolysaccharide and to occur tissue-specifically in the fat body and hemocytes. Our results suggest that lebocin as well as cecropin forms a multiple gene family in B. mori.

Amino Acid Sequence↗
PubMed1998

Occurrence of pyridoxal 5'-phosphate-dependent serine racemase in silkworm, Bombyx mori.

D-Serine is known to occur in the silkworm Bombyx mori as well as in the mammalian central nervous systems. We found that serine racemase occurs in the insect, catalyzing the conversion of L-serine to its antipode. The enzyme was partially purified from pupae of the insect, and was inactivated by treatment with hydroxylamine and reactivated with pyridoxal 5'-phosphate (PLP). L-Alanine was racemized slowly by the enzyme at a rate of only about 6% of that of L-serine, and L-arginine and L-glutamine were inert as substrates. Therefore, the enzyme is a member of PLP-dependent amino acid racemases, and is distinct from alanine racemase (EC 5.1.1.1) and amino acid racemase with low substrate specificity (EC 5.1.1.10). This is the first report of the occurrence of serine racemase in eukaryotes producing D-serine.

Animals↗
PubMed2001

Molecular cloning of silkworm paralytic peptide and its developmental regulation.

The silkworm paralytic peptide (PP) is a member of the ENF peptide family that exerts multiple biological activities involved in defense reaction and growth regulation. We isolated its cDNA and examined mRNA expression profiles. cDNA encoded 131 amino acids from which the 23-residue PP sequence was found at the C-terminal portion. Immunoblot analysis and paralytic activity assay indicated that inactive pro-protein in larval hemolymph was processed into active peptide immediately after bleeding. In the last larval instar, 0.6-kb PP mRNA was expressed in various tissues, of which the fat body was predominant. Its expression in the fat body decreased during the feeding period and then increased during metamorphic process. Juvenile hormone and 20-hydroxyecdysone upregulated its expression. At the embryonic stage, 1.5-kb mRNA, in addition to 0.6-kb mRNA, was expressed from 1 day after oviposition to hatching. PP was thus expressed stage-specifically under hormonal control.

Amino Acid Sequence↗
PubMed2001

Production of biologically active recombinant bovine interferon-gamma by two different baculovirus gene expression systems using insect cells and silkworm larvae.

The full-length bovine interferon-gamma (bIFN-gamma) cDNA, including the secretion signal peptide coding region was recloned into baculovirus transfer vectors pAcYM1 and pBm050. These vectors were co-transfected with Autographa californica nuclear polyhedrosis virus (AcNPV) or Bombyx mori nuclear polyhedrosis virus (BmNPV) DNA into Spodoptera frugiperda cells (SF21AE) and Bombyx mori cells (BmN), respectively. The recombinant viruses, named AcBIFN-gamma and BmBIFN-gamma, were then recovered. Recombinant bIFN-gamma (rbIFN-gamma) was accumulated in the culture fluid of AcBIFN-gamma-infected Trichoplusia ni cells and BmBIFN-gamma-infected silkworm larvae. These rbIFN-gamma forms were shown to be glycosylated 20 and 22 kDa proteins as confirmed by SDS-PAGE and tunicamycin treatment. These products were sensitive to cystein proteinase. Both rbIFN-gamma proteins, showed high-level biological activities by plaque reduction assay using vesicular stomatitis virus, and MHC class II antigen induction on bovine macrophage cells.

Animals↗
PubMed2002

Expression of biologically active recombinant equine interferon-gamma by two different baculovirus gene expression systems using insect cells and silkworm larvae.

The full-length equine interferon-gamma (eIFN-gamma) cDNA, including the secretion signal peptide coding region, was recloned into baculovirus transfer vector pAcYM1. This vector was co-transfected with Autographa californica nuclear polyhedrosis virus DNA or hybrid nuclear polyhedrosis virus DNA into Spodoptera frugiperda cells. The recombinant viruses, named AcEIFN-gamma and HyEIFN-gamma, were then recovered. Recombinant eIFN-gamma (reIFN-gamma) was accumulated in the culture fluid of the AcEIFN-gamma or HyEIFN-gamma infected Tricoplusia ni -derived cell line, BTI TN 5B1-4, and hemolymph of HyEIFN-gamma infected silkworm larvae. These reIFN-gamma forms were shown to be 14, 16, 18 and 20kDa proteins, and glycosylated as confirmed by SDS-PAGE and tunicamycin treatment. Both reIFN-gamma proteins, showed high-level biological activities to vesicular stomatitis virus by cytopathic effect reduction assay, and MHC class II antigen induction on the equine fetal kidney-78 cell line.

Animals↗
PubMed2000

MBF2 is a tissue- and stage-specific coactivator that Is regulated at the step of nuclear transport in the silkworm Bombyx mori.

Coactivators MBF1 and MBF2 mediate BmFTZ-F1-dependent transcriptional activation in vitro by interconnecting BmFTZ-F1, TATA binding protein TBP, and TFIIA. Here, we analyzed temporal and spatial expression patterns of MBF2 during embryonic and larval development of the silkworm Bombyx mori. MBF2 was detected in unfertilized eggs and embryos until stage 26. In stage 22 embryos, MBF1, MBF2, and BmFTZ-F1 colocalize in neural cells. During the larval stage, MBF2 was not expressed in the fat body and trachea. In the silk gland, MBF2 mRNA was constitutively expressed, but MBF2 protein appeared in the period between the second day and the molting D3 stage in both the third and the fourth instars and then disappeared. MBF2 was also detected on the second and third days of the fifth instar. Immunostaining during the fourth molt showed that MBF1, MBF2, and BmFTZ-F1 localize in the nucleus only at the D3 stage, while the two cofactors are present in the cytoplasm at other stages. Immunoprecipitation experiments suggested that MBF1, MBF2, and BmFTZ-F1 form a complex at the D3 stage. Transient expression of these factors in Schneider cell line 2 revealed that MBF1 and MBF2 localize to the nucleus and enhance BmFTZ-F1-dependent transcription only when all three factors are present. These data illustrate the functional regulation of MBF1 and MBF2 at the step of nuclear transport and implicate MBF2 in tissue- and stage-specific transcription.

Animals↗
PubMed1997

Changes in protein metabolism in hemolymph and fat body of the silkworm, Bombyx mori (Lepidoptera: Bombycidae) in response to organophosphorus insecticides toxicity.

Changes in protein metabolism were studied in hemolymph and fat body of 5th instar silkworm Bombyx mori exposed to lethal and sublethal doses of fenitrothion and ethion. The total protein content indicated a depletion followed by a concomitant increase in accumulation of free amino acids. Concurrently, the activity of protease in both of the tissues was also increased. A sharp enhancement in the activities of alanine aminotransferase and aspartate aminotransferase paralleled the elevation of glutamate dehydrogenase activity in the tissues studied. All these changes clearly documented the induction of severe proteolysis and transamination of amino acids.

Alanine Transaminase↗