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PubMed2006

Interaction of subtilisin BPN' and recombinant fungal protease inhibitor F from silkworm with substituted P1 site residues.

Fungal protease inhibitor F (FPI-F) from silkworm inhibits subtilisin and fungal proteases. FPI-F mutants P(1) residues of which, Thr(29), were replaced with Glu, Phe, Gly, Leu, Met, and Arg, were prepared. The inhibitory activities of mutated FPI-F against subtilisin and other mammalian proteases indicated that FPI-F might be a specific inhibitor toward subtilisin-type protease.

Amino Acid Sequence↗
PubMed2006

A novel type of receptor cDNA from the prothoracic glands of the silkworm, Bombyx mori.

A cDNA encoding a novel heptahelical receptor from the prothoracic glands of the silkworm, Bombyx mori was cloned and sequenced during screening of a prothoracicotropic hormone (PTTH) receptor. Orthologs of this receptor are found not only in insects, but also in the vertebrates. In B. mori, ubiquitous expression of the mRNA was observed in the larva. Also, a higher expression level in the prothoracic glands was observed before molting and metamorphosis and was impaired after pupal molting. But, further analysis is required to confirm whether this receptor cDNA encodes the PTTH receptor.

Amino Acid Sequence↗
PubMedDate not supplied

Establishment and characterization of a continuous cell line from pupal ovaries of Japanese oak silkworm Antheraea yamamai Guerin-Meneville.

Pupal ovaries of the wild oak silkworm Antheraea yamamai Guerin-Meneville were cultured in MGM-448 (Modified Grace Medium-448) medium containing 10% fetal bovine serum. After the primary culture was set up in 1988, a continuous cell line was obtained in 1991, designated as NISES-Anya-0611 (Anya-0611). The population doubling time was 54 hrs. and 19 min. at 96 passages and 88 hrs. and 29 min. at 387 passages. Spindle-shaped and spherical cells coexisted in the cell group. The cell line karyotype line was typical of lepidopteran cell lines, consisting of numerous small chromosomes. The cell line was distinguished from other lepidopteran cell lines by comparing malic enzyme, phosphoglucose isomerase, phosphoglucose mutase, and isocitric dehydrogenase isozyme patterns. The cell line was highly infected to the Antheraea yamamai nuclear polyhedrosis virus (Anya NPV). The luciferase gene of recombinant Bm NPV (BmNPVP6ETL) was able to express in the cell line, too, so that luciferase recombinant products were able to be detected in the cell body and in supernatant. The Anya NPV clone group was isolated on the cell seat using plaque purification.

Animals↗
PubMed1993

Homogeneous production of feline interferon in silkworm by replacing single amino acid code in signal peptide region in recombinant baculovirus and characterization of the product.

In a previous paper we reported that we constructed a recombinant baculovirus named BmFeIFN1 which produced recombinant feline interferon (FeIFN) in silkworm after infection. High purification of FeIFN in body fluid from the larvae revealed that two kinds of FeIFN were produced by the BmFeIFN1. The difference between the two in the NH2-terminal amino acid sequence was clarified, and two kinds of processing at different sites in FeIFN precursor were suggested. Changing one residue of the amino acid sequence in deduced signal peptide by site directed mutagenesis of encoding cDNA led to the production of homogeneous FeIFN whose NH2-terminal three amino acid sequence was identical to the conserved sequence of human interferon-alpha. We designated the FeIFN produced as rFeIFN. Amino acid sequence analysis revealed that rFeIFN consisted of 170 amino acid residues. The COOH-terminal amino acid of the rFeIFN is Glu which is located at one amino acid residue upstream to the COOH-terminal amino acid deduced from the nucleotide sequence. Positive periodic acid Schiff reaction, undetectability of Asn at position 79 by automated protein sequencer, and detectability of N-acetylglucosamine not N-acetylgalactosamine suggested that rFeIFN was N-glycosylated. rFeIFN was stable at pH 1.5 at 4 degrees C for at least 50 days, and had an antiviral action on feline calicivirus or feline herpesvirus in vitro. Its isoelectric point was pI 6.5. Comparing the structure and biosynthesis of rFeIFN with those of HuIFNs, rFeIFN may be classified as omega-type.

Amino Acid Sequence↗
PubMed1996

Western blotting using recombinant Hantaan virus nucleocapsid protein expressed in silkworm as a serological confirmation of hantavirus infection in human sera.

Recombinant Hantaan virus nucleocapsid protein expressed in silkworm larvae was applied as a serological diagnostic antigen in Western blots (WB) of human sera. The sensitivity of this method was similar to that of the IFA test. Hemorrhagic fever with renal syndrome (HFRS) and nephropathia epidemica diagnosed by their cross-reactivity in WB. The specificity of this method was higher than that of IFA test because the background was low. Sera that exhibited high background staining in the IFA test were readily diagnosed with this method. We recommended WB using recombinant Hantaan virus nucleocapsid antigen as a confirmatory procedure for the serodiagnosis of hantavirus.

Animals↗
PubMed2004

QTL mapping of economically important traits in silkworm (Bombyx mori).

A backcrossed population (BC1) was derived from a cross between C100 and Dazao. AFLP technique was employed for mapping the QTLs. The QTLs for the whole cocoon weight, cocoon shell weight, ratio of cocoon shell, weight of pupae etc. were analyzed and 11 QTLs were detected based on the constructed linkage map. Two QTLs for whole cocoon weight were localized on linkage group 6 and 19; three QTLs for cocoon shell weight were localized on linkage group 3, 14 and 19; three QTLs for ratio of cocoon shell were localized on the linkage group 2, 11 and 15, and three QTLs for the weight of pupae were localized on linkage 2, 14 and 19. All these have laid an important base for the marker assisted breeding of the silkworm.

Animals↗
PubMed2005

Analysis of cytochrome P450 genes in silkworm genome (Bombyx mori).

We have searched the Bombyx mori genome for members of the major enzyme family, the Cytochrome P450s, which carry out multiple reactions to enable organisms to rid themselves of foreign compounds. As a result, 86 putative P450s were discovered in silkworm genome, which are thought to belong to 32 subfamilies. A comparative genomic analysis with Drosophila melanogaster reveals that the two insects have some similar P450 distribution patterns but still have some obvious differences. Especially, the diverse distribution exists in 7 p450 subfamilies, which are CYP4A, CYP4C, CYP4D, CYP6A, CYP6AE, CYP6B and CYP9A. Furthermore, we collected expression sequence tag (EST) evidence for 49 putative P450s genes, which are expressed at the transcriptional level and more likely to be true P450s.

Animals↗
PubMed2004

A scaleless wings mutant associated with tracheal system developmental deficiency in wing discs in the silkworm, Bombyx mori.

A mutant of Bombyx mori has wings with few scales and is named scaleless. We investigated the morphology of this mutant and found that it had many fewer wing scales than the corresponding wild type (WT) silkworm and that the remaining scales were smaller in shape with fewer furcations. Reciprocal transplantation of wing discs between scaleless and WT revealed that the WT wing disc could develop into a small wing with scales after transplantation into a scaleless larva; however, the scaleless wing disc developed into a small wing without scales in a WT larva. Upon dissection of WT and scaleless wing discs at different stages from the fifth instar larva to adulthood, no obvious differences were found before pupation. However, after pupation, tracheae produced from WT wing veins extended to the lacunae between the veins and formed a network on the second day after pupation, whereas this did not happen in scaleless. At the same time, no marked difference in adult body tracheal development was found between the mutant and wild type. Furthermore, if the surface of a wing disc was cut and its veins injured, the resulting wing also had fewer scales than the corresponding WT. Also, we found that higher partial pressure of O2 could rescue the loss of scales in scaleless. These data suggest that the factors affecting the growth of scales were not produced in the hemolymph, but in the wing disc itself. It is also implied that wing scale development is dependent on the correct organization of the tracheal system in the wing disc.

Animals↗
PubMed1983

Cinnabarinic acid formation in Malpighian tubules of the silkworm, Bombyx mori. Participation of catalase in cinnabarinic acid formation in the presence of manganese ion.

Cinnabarinic acid was formed from 3-hydroxyanthranilic acid during incubation with a soluble fraction from Malpighian tubules of the silkworm, Bombyx mori, in the presence of manganese ion. The enzyme having this activity was purified to homogeneity by ammonium sulfate fractionation, gel filtration and ion exchange chromatography. Enzyme activity was accompanied by parallel catalase activity at all steps of purification; the two activities could not be separated from each other. The purified protein was concluded to be catalase. Manganese was shown to be present in 0.1 mM concentration in Malpighian tubules of Bombyx mori. These findings suggest that in Malpighian tubules catalase participates in the formation of cinnabarinic acid. A possible mechanism for the formation of cinnabarinic acid from 3-hydroxyanthranilic acid by catalase in the presence of manganese ion is proposed.

Animals↗
PubMed1988

Amino-acid sequences of two basic chymotrypsin inhibitors from silkworm larval hemolymph.

Amino-acid sequences of two basic chymotrypsin inhibitors from silkworm hemolymph (SCI-I and SCI-II) are determined. They are composed of each 62 amino-acid residues with differences in only two positions to each other. They both contain six half cystines in a similar arrangement as that of Kunitz-type proteinase inhibitor, except for the one amino-acid insertion in the first cysteine frame. The inhibitory activity of SCI-II against trypsin should be attributed to Lys44 displacing Gln44 in SCI-I which has no antitryptic activity.

Amino Acid Sequence↗
PubMed1994

Expression of biologically active monomeric form of human M-CSF in baculovirus infected silkworm, Bombyx mori.

The human macrophage colony stimulating factor (hM-CSF) in its monomeric form has been over-produced in BmN cells and in silkworm larvae infected with the recombinant baculovirus Bm284M-CSF. The recombinant monomeric M-CSF (rhM-CSF) exhibited the activity of 8-14 x 10(4) units/ml of cell culture medium. When the insect larvae were infected with the recombinant virus, the maximum rhM-CSF was expressed 4-5 days post infection with an activity of 3 x 10(6) units/ml hemolymph. The monomeric rhM-CSF was purified to homogeneity through three steps of purification. A pilot purification yielded 1 mg of homogeneous monomeric rhM-CSF from 10 larvae. The purified rhM-CSF monomers gradually dimerized in vitro. In contrast, the crude or the semi-purified monomers did not dimerize in vitro, indicating that the presence of an unknown moiety in the rhM-CSF preparations obtained from hemolymph interfered with dimerization.

Alkylation↗
PubMedDate not supplied

Molecular size of the diapause hormone of the silkworm Bombyx mori.

The diapause hormone (DH) responsible for arrested development of the silkworm Bombix mori consists of two active principles of peptide (A and B). Since both hormones form aggregates in aqueous phases, the molecular weights were determined by gel permeation chromatography of Merckogel OR 6000 using methanol-dichloromethane mixture as the developing agent. Gramicidins and modified peptides soluble in the organic solvents were used as the standard markers for the molecular weight measurements of the hormones. The molecular weights of DH-A and -B are estimated to be 3300 +/- 400 and 2000 +/- 200, respectively.

Animals↗
PubMed2004

Survey and analysis of microsatellites in the silkworm, Bombyx mori: frequency, distribution, mutations, marker potential and their conservation in heterologous species.

We studied microsatellite frequency and distribution in 21.76-Mb random genomic sequences, 0.67-Mb BAC sequences from the Z chromosome, and 6.3-Mb EST sequences of Bombyx mori. We mined microsatellites of >/=15 bases of mononucleotide repeats and >/=5 repeat units of other classes of repeats. We estimated that microsatellites account for 0.31% of the genome of B. mori. Microsatellite tracts of A, AT, and ATT were the most abundant whereas their number drastically decreased as the length of the repeat motif increased. In general, tri- and hexanucleotide repeats were overrepresented in the transcribed sequences except TAA, GTA, and TGA, which were in excess in genomic sequences. The Z chromosome sequences contained shorter repeat types than the rest of the chromosomes in addition to a higher abundance of AT-rich repeats. Our results showed that base composition of the flanking sequence has an influence on the origin and evolution of microsatellites. Transitions/transversions were high in microsatellites of ESTs, whereas the genomic sequence had an equal number of substitutions and indels. The average heterozygosity value for 23 polymorphic microsatellite loci surveyed in 13 diverse silkmoth strains having 2-14 alleles was 0.54. Only 36 (18.2%) of 198 microsatellite loci were polymorphic between the two divergent silkworm populations and 10 (5%) loci revealed null alleles. The microsatellite map generated using these polymorphic markers resulted in 8 linkage groups. B. mori microsatellite loci were the most conserved in its immediate ancestor, B. mandarina, followed by the wild saturniid silkmoth, Antheraea assama.

Animals↗
PubMed2006

A second-generation integrated map of the silkworm reveals synteny and conserved gene order between lepidopteran insects.

A second-generation linkage map was constructed for the silkworm, Bombyx mori, focusing on mapping Bombyx sequences appearing in public nucleotide databases and bacterial artificial chromosome (BAC) contigs. A total of 874 BAC contigs containing 5067 clones (22% of the library) were constructed by PCR-based screening with sequence-tagged sites (STSs) derived from whole-genome shotgun (WGS) sequences. A total of 523 BAC contigs, including 342 independent genes registered in public databases and 85 expressed sequence tags (ESTs), were placed onto the linkage map. We found significant synteny and conserved gene order between B. mori and a nymphalid butterfly, Heliconius melpomene, in four linkage groups (LGs), strongly suggesting that using B. mori as a reference for comparative genomics in Lepidotera is highly feasible.

Animals↗
PubMed2000

Effects of applaud on the growth of silkworm (Lepidoptera: Bombycidae).

An experiment was carried out to evaluate the effect of the insecticide Applaud (buprofezin 25% WP) on the silkworm Bombyx mori (L.). This insecticide belongs to the class of insect growth regulators (IGR). The larvae were fed on leaves treated with 3 different concentrations (0.5, 1, 2 g/liter) of Applaud on the 1st d of each instar. Analysis of data with the Tukey-Kramer test at 1% significant level revealed that mortality and larval duration did not differ among the treatments. On the contrary, the larval weight, which was estimated just before mounting (procedure during which the mature larva climbing on a branch or other material to spin the cocoon), differed among the treatments. Also, cocoon weight, shell weight, and cocoon sericin and fibroin content were different among the treatments, except the shell cocoon ratio. Maximum weight was observed in the controls and minimum in the last instar treatments. Our data suggest that supplementation of Applaud through food to larvae does not affect their mortality rate. On the contrary, it affects larval growth and cocoon parameters.

Animals↗
PubMed2004

Ecdysteroids during early embryonic development in silkworm Bombyx mori: metabolism and functions.

It has been well established that eggs of insects, including those of the silkworm Bombyx mori, contain various molecular species of ecdysteroids in free and conjugated forms. In B. mori eggs, 20-hydroxyecdysone (20E) is a physiologically active molecule. In nondiapause eggs, 20E is produced by the conversion of maternal conjugated ecdysteroids (ecdysteroid-phosphates) and by de novo biosynthesis. In contrast, in diapause eggs, neither of these metabolic processes occurs. In de novo biosynthesis of 20E in B. mori eggs, hydroxylation at the C-20 position of ecdysone, which is catalyzed by ecdysone 20-hydroxylase, is a rate-limiting step. Furthermore, we found that a novel enzyme, called ecdysteroid-phosphate phosphatase (EPPase), specifically catalyzes the conversion of ecdysteroid-phosphates to free ecdysteroids. The developmental changes in the expression pattern of EPPase mRNA correspond closely to changes in the enzyme activity and in the amounts of free ecdysteroids in eggs. EPPase is localized in the cytosol of yolk cells, and the bulk of maternal ecdysteroid-phosphates is bound to vitellin and stored in yolk granules. The vitellin-bound ecdysteroid-phosphates are scarcely hydrolyzed by EPPase. Therefore, to examine how ecdysteroid-phosphates are hydrolyzed by EPPase during embryonic development further investigations were focused on yolk granules. Recent data indicate that acidification in yolk granules, induced by vacuolar H(+)-ATPase, triggers the dissociation of ecdysteroid-phosphates from the vitellin-ecdysteroid-phosphates complex and the dissociated ecdysteroid-phosphates are released from yolk granules to the cytosol. To explain the process of the increase in the level of 20E during embryonic development in B. mori eggs, a possible model is proposed.

Animals↗
PubMed2004

FMRFamide-expressing efferent neurons in eighth abdominal ganglion innervate hindgut in the silkworm, Bombyx mori.

The tetrapeptide FMRFamide is known to affect both neural function and gut contraction in a wide variety of invertebrates and vertebrates, including insect species. This study aimed to find a pattern of innervation of specific FMRFamide-labeled neurons from the abdominal ganglia to the hindgut of the silkworm Bombyx mori using the immunocytochemical method. In the 1st to the 7th abdominal ganglia, labeled efferent neurons that would innervate the hindgut could not be found. However, in the 8th abdominal ganglion, three pairs of labeled specific efferent neurons projected axons into the central neuropil to eventually innervate the hindgut. Both axons of two pairs of labeled cell bodies in the lateral rind and axons of one pair of labeled cell bodies in the posterior rind extended to the central neuropil and formed contralateral tracts of a labeled neural tract with a semi-circular shape. These labeled axons ran out to one pair of bilateral cercal nerves that extended out from the posterior end of the 8th abdominal ganglion and finally to the innervated hindgut. These results provide valuable information for detecting the novel function of FMRFamide-related peptides in metamorphic insect species.

Animals↗
PubMed2005

Release of ecdysteroid-phosphates from egg yolk granules and their dephosphorylation during early embryonic development in silkworm, Bombyx mori.

Newly laid eggs of many insect species store maternal ecdysteroids as physiologically inactive phosphoric esters. In the silkworm Bombyx mori, we previously reported the presence of a specific enzyme, called ecdysteroid-phosphate phosphatase (EPPase), which catalyzes the dephosphorylation of ecdysteroid-phosphates to increase the amount of free ecdysteroids during early embryonic development. In this study, we demonstrated that (1) EPPase is found in the cytosol of yolk cells, (2) ecdysteroid-phosphates are localized in yolk granules, being bound to the yolk protein vitellin (Vn), and (3) Vn-bound ecdysteroid-phosphates are scarcely hydrolyzed by EPPase, although free ecdysteroid-phosphates are completely hydrolyzed by EPPase. Thus, we investigated the mechanism by which ecdysteroid-phosphates dissociate from the Vn-ecdysteroid-phosphate complex, and indicated that the acidification of yolk granules causes the dissociation of ecdysteroid-phosphates from the Vn-ecdysteroid-phosphate complex and thereby ecdysteroid-phosphates are released from yolk granules into the cytosol. Indeed, the presence of vacuolar-type proton-translocating ATPase in the membrane fraction of yolk granules was also verified by Western blot analysis. Our experiments revealed that Vn functions as a reservoir of maternal ovarian ecdysteroid-phosphates as well as a nutritional source during embryonic development. This is the first report showing the biochemical mechanism by which maternal Vn-bound ecdysteroid-phosphates function during early embryonic development.

Animals↗