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PubMed1976

Comparison of mode of activation of guanosine 3':5'-monophosphate-dependent and adenosine 3':5'-monophosphate-dependent protein kinases from silkworm.

Guanosine 3':5'-monophosphate (cyclic GMP)-dependent protein kinase (protein kinase G) partially purified from silkworm pupae was selectively activated by cyclic GMP at lower concentrations. Nevertheless, the enzyme seemed to differ from adenosine 3':5'-monophosphate-dependent protein kinase (protein kinase A) with respect to the mode of response to cyclic nucleotides. The catalytic activity and cyclic GMP-binding activity were not dissociated by cyclic GMP in a manner similar to that described for protein kinase A. The enzyme was not inhibited by regulatory subunit of protein kinase A nor by protein inhibitor. A sulfhydryl compound such as 2-mercaptoethanol or glutathione was essential for the activation by cyclic GMP, and an extraordinary high concentration of either Mg2+ (100 mM) or Mn2+ (25 mM) was needed for maximal stimulation by cyclic GMP. A polyamine such as spermine, spermidine, or putrescine could substitute partly for the cation. Kinetic analysis indicated that Km for ATP was decreased whereas Ka for cyclic GMP was increased significantly at high concentrations of the cation. The effect of the cation to decrease Km for ATP was not evident in the absence of a sulfhydryl compound. These characteristics of protein kinase G described above were not observed for protein kinase A which was obtained from the same organism.

Animals↗
PubMed1976

Guanosine 3':5'-monophosphate-dependent protein kinase from silkworm, properties of a catalytic fragment obtained by limited proteolysis.

Although guanosine 3':5'-monophosphate (cyclic GMP)-dependent protein kinase (protein kinase G) which was partially purified from silkworm pupae was not dissociated by cyclic GMP into catalytic and regulatory subunits as described for adenosine 3':5'-monophosphate-dependent protein kinase (protein kinase A) (Takai, Y., Nakaya, S., Inoue, M., Kishimoto, A., Nishiyama, K., Yamamura, H., and Nishizuka, Y. (1976) J. Biol. Chem. 251, 1481-1487), limited proteolysis with trypsin resulted in the formation of catalytic and cyclic GMP-binding fragments which showed molecular weights of approximately 3.4 X 10(4) and 3.6 X 10(4), respectively (the molecular weight of native protein kinase G was 1.4 X 10(5)). The catalytic fragment did not bind cyclic GMP and was fully active in the absence of the cyclic nucleotide. The fragment did not show an absolute requirement for a sulfhydryl compound and high concentrations of Mg2+ (50 to 100 mM), both of which were necessary for the maximal activation of native protein kinase G. The catalytic fragment was not inhibited by the cyclic GMP-binding fragment nor by the regulatory subunit of protein kinase A. Inversely, the cyclic GMP-binding fragment was unable to inhibit the catalytic subunit of protein kinase A. Protein inhibitor, which was described for protein kinase A, was inert for the catalytic fragment.

Animals↗
PubMed1975

Functional specificity of guanosine 3':5'-monophosphate-dependent and adenosine 3':5'-monophosphate-dependent protein kinases from silkworm.

Adenosine 3':5'-monophosphate-dependent protein kinase partially purified from silkworm pupae shows identical functional activities with those of mammalian protein kinases; the insect and mammalian kinases are completely exchangeable in the phosphorylation of muscle glycogen phosphorylase kinase and glycogen synthetase resulting in the activation and inactivation of the respective enzymes. In contrast, guanosine 3':5'-monophosphate-dependent protein kinase obtained from the same organism is totally inactive in this role and phosphorylates different, mainly seryl and some threonyl, residues of acceptor proteins. Substrates of the latter kinase intimately involved in the regulation of biological processes have remained unknown.

Animals↗
PubMed1990

Genetically defined membrane-bound and soluble alkaline phosphatases of the silkworm: their discrete localization and properties.

In the midgut tissue of the silkworm, Bombyx mori, alkaline phosphatase isozymes, membrane-bound (m-ALP) and soluble (s-ALP) forms are controlled by non-allelic genes on the same chromosome. We purified and characterized both ALPs to elucidate their possible functions and to compare with mammalian ALPs. Both forms were found to be similar Mr = 68,000 in gel permeation chromatography and as a single subunit as a monomer in SDS-polyacrylamide gel electrophoresis with Mr = 58,000 for m-ALP and Mr = 61,000 for s-ALP. The pH optima of ALPs were 10.9 (m-ALP) and 9.8 (s-ALP), and the former was extremely stable even in pH 10-12 which accords with the physiological milieu in Bombyx midgut lumen. Both ALPs had similar substrate specificities. L-cysteine inhibited strongly both ALPs, but inhibitory effects of L-phenylalanine, L-homoarginine, and L-leucine were undetectable for s-ALP and very weak for m-ALP. The antibody raised against purified m-ALP recognized m-ALP but not purified s-ALP and vice versa. Rocket-immunoassay showed that m-ALP was distributed in similar levels along the length of midgut except for the most anterior portion. Seventy percent of s-ALP activity existed in the last one-third of midgut. Immunohistochemical study revealed that the m-ALP was localized at the brush border of columnar cells in the middle and posterior midgut epithelia. In contrast, the s-ALP was localized at the apical surface of goblet cells through the length of midgut. We detected ATPase activity in the purified s-ALP preparation; Mg2+ was essential for the ATPase activity and the activity also increased with KHCO3 but not with KCl. The solubilization test of m- ALP with various agents was attempted and the relationship between m-ALP and the digestive fluid-ALP was discussed.

Alkaline Phosphatase↗
PubMed1988

hst-1 transforming protein: expression in silkworm cells and characterization as a novel heparin-binding growth factor.

A protein encoded by an hst-1 transforming gene was expressed in silkworm-derived BmN cells and secreted into the culture medium using a recombinant baculovirus vector. The strong affinity for heparin of the secreted protein made it possible to purify the hst-1 protein to homogeneity in a two-step procedure. The purified hst-1 protein has a molecular weight of 18,000 and stimulates both DNA synthesis in NIH3T3 cells and human umbilical vein endothelial cell proliferation. In addition, morphological changes and anchorage-independent growth of NIH3T3 cells are induced by this product. These results show that the hst-1 transforming protein is a novel heparin-binding growth factor as predicted by nucleotide sequence analysis.

Animals↗
PubMed1987

Tissue-specific and periodic changes in the nuclease sensitivity of the fibroin gene chromatin in the silkworm Bombyx mori.

Nuclei of substantial purity were isolated from the middle or posterior silk glands of the silkworm Bombyx mori larvae. Both the fibroin H- and L-chain gene sequences in the isolated nuclei from the posterior silk glands of the fifth instar larvae, where the genes are transcribed actively, are extremely sensitive to the digestion with DNaseI; on the other hand, these sequences in the middle silk gland nuclei from the same larvae, where the genes are not expressed, are markedly resistant to the digestion. The H-chain gene sequences in the posterior silk gland nuclei from the fifth instar larvae are also highly susceptible to the digestion with micrococcal nuclease, HinfI, and HhaI. The digestion products with micrococcal nuclease show a continuous size distribution. The H-chain gene sequences in the middle silk gland nuclei or the posterior silk gland nuclei from the fourth molting stage are cleaved partially into nucleosome dimer to oligomer sizes upon digestion with higher concentrations of micrococcal nuclease, suggesting that the inactive forms of the H-chain gene chromatin are constructed by folding of the chromatin fiber containing a regular array of nucleosomes. Hypersensitive sites to micrococcal nuclease are present near both ends of the second exon, a major body of the fibroin H-chain gene, in both the active and inactive forms of the chromatin. The DNaseI or micrococcal nuclease sensitivity of the H-chain gene chromatin in the posterior silk gland nuclei shows periodical changes corresponding to the intermolt-molt-intermolt cycle.

Animals↗
PubMed1986

The protein subunits of the double-stranded RNA dependent RNA polymerase and methyltransferase of the cytoplasmic polyhedrosis virus of silkworm, Bombyx mori.

The particles of CPV of silkworm contain double-stranded RNA polymerase and methyltransferase. It was reported in a previous paper that the genome-enzyme complex could be isolated. The genome-enzyme complex shows high enzyme activity of RNA polymerase and methyltransferase in spite of the fact that it consists of only 5 percent of the protein. In order to clarify the protein subunits of the RNA polymerase and methyltransferase, two methods were adopted. The SDS-polyacrylamide gel electrophoretogram showed that the 125I-labeled genome-enzyme complex of CPV contained three protein components in molecular weight of 33 K, 67 K and 142 K daltons respectively and each protein component of them consisted of more than two protein subunits with different isoelectric points in 2-dimensional electrophoretogram. The antibody to the five protein components (P1, P2, P3, P4, P5) was prepared and used to inhibit the enzyme activities of RNA polymerase and methyltransferase. It showed that the RNA polymerase was inhibited by the antibody to proteins P1, P2 and P4, whereas the methyltransferase was mainly inhibited by the antibody to protein P1.

Animals↗
PubMed1979

[Ultracytological studies of the morphogenesis and structure of the nuclear polyhedrosis virus in the silkworm moth, Bombyx mori L].

An electron-microscopic investigation was made on hypodermal tissues of silkworms spontaneously infested by nuclear polyhedral disease, due to low temperature stress. It was established that the polyhedral virus is formed in the viroplasma produced after viral cell infection, is included in the intimate and developing membrane singly or in fascicles containing several (up to 9) and is finally incapsulated in polyhedral protein. Besides viral rods, various polymorphic forms were observed in the nucleus and around the polyhedras in the process of formation, which are considered as viral substructures (or nucleocapsidless viruses), membrane structures and surplus synthetized polyhedral protein. It can be presumed that virus replication in single cell nucleus is a continuous process which goes on until complete nuclear structure depletion.

Animals↗
PubMed1985

Changes in the transaminase activities in the middle and posterior silk-gland tissues of eri-silkworm, Philosamia ricini, in relation to spinning process.

The middle silk gland tissue of eri-silkworm exhibits a higher glutamate-oxaloacetate transaminase activity (about twice) than that of the glutamate-pyruvate transaminase, while the posterior silk gland tissue exhibits a higher (three to four times) glutamate-pyruvate transaminase activity than that of the glutamate-oxaloacetate transaminase.

Alanine Transaminase↗
PubMed1979

[Biological method of determining the capacity of mulberry silkworm eggs which remain unpigmented for development].

To determine the stage of the silkworm eggs which did not acquire grey colour due to the serose membrane pigmentation and, as a result, preserved yellow colour, it is suggested to activate such eggs to parthenogenetic development of ameiotic or meiotic type. The eggs lost at the early developmental stages after activation will remain yellow, whereas those arrested at metaphase I begin to develop and acquire the dark colour on the 3rd day. Examples are given for the effective utilization of the method.

Animals↗
PubMed1979

[Cytology of egg maturation in the silkworm (Bombyx mori L.) in artificial parthenogenesis].

The orientation of bivalentss in the first meiotic metaphase was studied on the squash preparations and sections of eggs in Bombyx mori L., Antheraea pernyi Guèr and Carpocapsa pomonella L. The reduction fissure of bivalents separating the homologous chromosomes lies in the plane of spindle equator; the equation fissure separating the sister chromatids is parallel to the long spindle axis. Complicated rearrangements are observed in the nuclei of the silkworm eggs stimulated to ameiotic parthenogenesis by the high temperature dissociation of bivalents, full destruction of spindle, formation of a new spindle and metaphase plate. The latter includes univalent chromosomes involved in the equation division. As a result, two genetically identical pronuclei with the somatic set of chromosomes are formed.

Animals↗
PubMed1982

[Isolation and properties of carboxylesterase from hemolymph of the silkworm Bombyx mori L].

An original procedure for isolation and purification of carboxylesterase from the hemolymph of stage V larvae of one of Bombyx mori strains including precipitation with 10% polyethyleneglycol, ion-exchange chromatography on Sephadex G-200 and chromatography on DEAE-Sephadex A-50, has been developed. The specific activity of the enzyme after purification makes up to 1250 units per mg of protein with a 59% yield. Some physicochemical properties of the enzyme (Mr = 69 000, pI congruent to 4.9, temperature optimum = 40 degrees, pH optimum = 7.2 Km for alpha-naphthyl- and beta-naphthylacetate = 0.11 X 10(-3) and 0.52 X 10(-3) M, respectively) have been determined. Using immunodiffusion in agar gel, the antigenic identity of the enzymes isolated from the hemolymph of two silkworm species has been established.

Animals↗
PubMed1983

Monoclonal antibody to RNA polymerase I of the silkworm.

RNA polymerase I has been purified from the silk glands of the silkworm and antibodies obtained from immunized BALB/C mice. Hybridomas were obtained by fusing spleen cells from the same mice with SP-2/0 cells. One of the cloned hybridomas was injected into mice to produce ascitic fluid. Both polyclonal and monoclonal antibodies were characterized for their reactivity with polymerase I by double immunodiffusion, enzyme-linked immunosorbent assay, and enzyme inhibition. The monoclonal antibody is active even at 1:100,000 dilution, is specific for the second largest subunit of RNA polymerase I, and does show some cross-reactivity with polymerases II and III. The monoclonal antibody when coupled to Sepharose binds polymerase I from crude extracts, and the bound polymerase I can be eluted. This antibody has been employed to localize RNA polymerase to the nuclei of Chironomus salivary glands. This and other monoclonal antibodies will be of considerable help as probes for the study of structure and function of RNA polymerases during active transcription.

Animals↗
PubMedDate not supplied

[Range of the hosts of the causative agent of pébrine (Nosema bombycis) in the mulberry silkworm].

Biological interrelations between the agent of microsporidiosis of the silkworm and local species of insects were studied. 7 species of Lepidoptera (Agrotis segetum, Chloridea obsoleta, Laphygma exigua, Plusia gamma, Pieris brassicae, P. rapae, Lymantria dispar) were infected with the suspension of Nosema bombycis spores. Results have shown that 6 species of insects are susceptible to Nosema bombycis excluding only the gipsy moth. So, N. bombycis can be considered to be a parasite with a wide range of hosts.

Animals↗
PubMed1980

[Virion polypeptides of the nuclear polyhedrosis virus of the silkworm].

The nuclear polyhedrosis virus of the silkworm B. mori was obtained by dissolution of polyhedra at pH 10,5. It was shown that the virus particles contain a protease, which cleaves a few virion polypeptides during the dissolution of polyhedra under alkaline conditions. The proteolytic activity is inactivated by polyhedra treatment with phenylmethylsulfonylfluoride, diisopropylfluorophosphate, HgCl2 and at 80 degrees. Sodium dodecyl sulfate polyacrylamide gel electrophoresis revealed 18 virion polypeptides with molecular weights ranging between 10000-110000. It was assumed that the virion includes the polyhedral protein and its fragments. A possible role of the polyhedral protein and its fragments in the virion is discussed.

Animals↗
PubMed1980

[Pathohistological and ultrastructural studies of the nuclear polyhedrosis virus in the silkworm (Bombyx mori L.)].

Histopathologic studies were carried out on fifth instar silkworm moths of the Super 1 x Super 2 hybrid infected orally with Baculovirus bombycis along with ultrastructural investigations of the pathogen itself. It was found that the earliest changes in the moths set in at the 60th hour post inoculation. They consisted in the aggregation of chromatin, and the formation of polyhedral bodies in the fatty body, hypodermis, and peritracheal matrix; these appeared in the glandular tissue too, but not earlier than the 120th hour, while in the hemolymph they were found at the 40th hour. The morphogenesis of the virus was followed up via the electron microscope, giving a description of its structure. It was found to replicate in the viral plasma formed in the nuclei of the infected cells. First the nucleocapsids emerged which were enveloped in a two layer outer (developing) membrane while they were in the viral plasma or in the space between it and the nuclear membrane (the so-called ring zone). Then these tended to thoroughly enter the ring zone and incorporate randomly into the polyhedral bodies. The virions were enveloped at the rate of one in the developing membrane, rarely being up to five per envelope. It was assumed that both at induction and at artificial infection the process, resp., the virus replication runs its course after one and the same pattern. However, the number of virions in the developing membrane depends on the tissue in whose cells the virus is replicated.

Animals↗
PubMed1981

[3H-Methyl]-methionine as possible methyl donor for formation of 5'-terminus of in vitro synthesized mRNA of cytoplasmic polyhedrosis virus of silkworm Bombyx mori.

The mRNA of the cytoplasmic polyhedrosis virus of silkworm Bombyx mori could be synthesized in vitro through the action of the virion associated RNA-polymerase in the presence of [3H-methyl]-methionine instead of S-adenosyl-L-methionine. The 3H-mRNA is isolated from the reaction mixture through a column of DEAE-Sephadex A-25 and digested with nuclease p1 and snake venom phosphodiesterase. The results of paper electrophoresis show that the methyl group of methionine is incorporated into the 5'-terminus of CPV mRNA. Even in the presence of S-adenosyl-L-methionine the [3H-methyl]-methionine could still function as a methyl donor for the formation of the 5'-caps of the mRNA of CPV.

Animals↗
PubMed1982

Isolation of genome-enzyme complex from cytoplasmic polyhedrosis virus of silkworm Bombyx mori.

The genome-enzyme complex is isolated from the silkworm cytoplasmic polyhedrosis virus with DEAE-Sephadex column chromatography after ultraviolet irradiation. The genome-enzyme complex shows both RNA-polymerase and methyltransferase activities while using 3H-UTP and [3H-methyl]-S-adenosyle-L-methionine as substrates. Like the double-stranded RNA genome of CPV, the genome-enzyme complex could be separated into nine segments on polyacrylamide gel electrophoresis. It is demonstrated that the RNA polymerase and methyl-transferase are tightly bound to the double-stranded RNA genome and that the individual segments of the genome-enzyme complex all possess RNA-polymerase and methyltransferase activities. It appears that each segment of the double-stranded RNA genome is transcribed independently.

Bombyx↗