SEARCH · PubMed Health

Results for “SILKWORMS”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed1999

Fluorescent Transgenic Silkworm.

The replacement of fibroin heavy chain gene in silkworm by site directed homologous recombination was studied The DNA fragment consisting of an IE promoter driving green fluorescent protein (GFP) gene as reporter flanked by pieces of the 5' and 3' sequences of the fibroin heavy chain gene of silkworm at two sides was transferred into silkworm eggs by electroporation Green fluorescent flecks were seen on three silkworms fifth instar among five thousand silkworms under UV light PCR analysis proved that the GFP gene was integrated into the genome of silkworm Southern hybridization of genomic DNA of one transgenic silkworm showed that the fibroin heavy chain gene was successfully knocked out and replaced by the reporter gene The transgenic silkworms could grow up to the fifth instar as normal but they could not spin silk while control ones do.

Journal Article↗

PubMed1999

Kinetic effect of silkworm hemolymph on the delayed host cell death in an insect cell-baculovirus system

The kinetic effect of silkworm hemolymph on host cell viability during a baculovirus-induced insect cell death process was investigated. Host cell viability after viral infection is important for replication of the baculovirus DNA containing a recombinant gene and expression of the cloned gene. The baculovirus-induced insect cell death process can be divided into a delay phase and a first-order death phase, which are characterized by a delay time (t(d)) and a specific death rate (k(d)), respectively. For 0-10% silkworm hemolymph in the media, higher concentrations resulted in longer delay times and lower specific death rates. By adding 10% silkworm hemolymph, the delay time increased from 72 to 164 h, and the specific death rate was reduced from 13.8 x 10(-)(3) to 6.0 x 10(-)(3) h(-)(1). In addition, host cell viability correlated with DNA fragmentation, which is the biochemical hallmark of apoptosis. This indicates that the silkworm hemolymph inhibits the baculovirus-induced insect cell apoptosis. However, the silkworm hemolymph did not affect the number of hypothetical targets, which represents host cell susceptibility to the baculovirus. The concentration of fetal bovine serum (FBS) in the medium did not affect the delay time, while lower concentrations of silkworm hemolymph resulted in shorter delay times. This means that the substance which increases the longevity of the host cell is not in the FBS but in the silkworm hemolymph.

Journal Article↗

PubMed2001

Altering Fibroin Heavy Chain Gene of Silkworm Bombyx mori by Homologous Recombination.

A gene unit, which encoded fibroin-like peptide, was synthesized and constructed. The unit was multimerized to about 2 400 bp using BamHI and BglII at each end of the unit, then was fused with gfp reporter gene. The fusion gene, flanked by the 5'and 3'sequence of the fibroin heavy chain gene of silkworm Bombyx mori, was transferred into the eggs of silkworm by electroporation. After the silkworms developed and spinned silk, 73 out of about 5 400 cocoons were brighter than normal ones under UV light. The protein extracted from the brighter cocoon could react with the GFP polyclonal antibodies. Genomic DNA from these silkworms and their progenies were analyzed. The integration of gfp gene into genomic DNA of silkworm and the occurrence of expected homologous recombination event had been proved by Southern hybridization. It was shown that gfp-fibroin like fusion gene had integrated into the genomic DNA of silkworm by homologous recombination and the phenotype of "brighter cocoon" could be used to select transgenic silkworms.

Journal Article↗

PubMed2002

[Effects of silkworm pupa oil on serum lipids level and platelet function in rats].

To observe the effects of silkworm pupa oil on serum lipids level and platelet function in rats, according to serum TG, TC level, 40 male Wistar rats are divided into four groups (normal control group, high fat control group, silkworm pupa oil group and silkworm pupa oil + VE group). The rats are fed different diets and six weeks later, serum lipids level and platelet function are measured. The results show that (1) Compared with high fat control group, serum TC, TG, LDL-C level, AI value, Platelet aggregability, plasma TXB2 level and T/P ratio decrease significantly while HDL-C level and 6-k-PGF1 level increase in silkworm pupa oil group; (2) Serum TC, LDL-C level, T/P ratio and platelet aggregability are significantly lower in silkworm pupa oil + VE group than in silkworm pupa oil group. It is suggested that silkworm pupa oil rich in alpha-linolenic acid can reduce serum lipids level and inhibit platelet aggregation, which is more effective with the supplementation with VE.

Animals↗

PubMed2004

Toxicity of two type II ribosome-inactivating proteins (cinnamomin and ricin) to domestic silkworm larvae.

Cinnamomin and ricin are two type II ribosome-inactivating proteins. They exhibited a different toxicity to domestic silkworm (Bombyx mori) larvae by oral feeding bioassay. The LC50 of ricin to the silkworm larvae at third instar was much lower than that of cinnamomin. When the isolated 80S ribosome from domestic silkworm pupae was treated separately with the reduced cinnamomin or the reduced ricin, a specific RNA fragment (R-fragment) was produced as characterized by 8 M urea-denatured polyacrylamide gel (3.5%) electrophoresis. The purified A-chains of both cinnamomin and ricin showed a slightly different RNA N-glycosidase activity to the domestic silkworm pupal ribosome. It was proposed that the difference of their toxicity to domestic silkworm larvae was not related to their A-chains but to the properties of their B-chains. It was also found that the vomit obtained from the midgut of domestic silkworm larvae could hydrolyze these two proteins apparently to a similar extent.

Algal Proteins↗

PubMed2007

Germ line transformation of the silkworm, Bombyx mori, using the transposable element Minos.

We investigated the use of Minos as a vector for transgenesis in the silkworm, Bombyx mori. We first constructed a vector plasmid with the green fluorescent protein (GFP) gene fused with the silkworm cytoplasmic actin gene (A3) promoter, and a helper plasmid with the Minos transposase gene controlled by the same A3 promoter. Injection of the vector and helper plasmid DNA into silkworm eggs produced transgenic animals in the following generation. The efficiency of transgenic silkworm production using this method was much lower than that obtained using piggyBac-mediated germ line transformation. However, >40-fold increase in the efficiency of producing transgenic silkworms was obtained using an in vitro synthesized source of Minos transposase mRNA. We conclude that the Minos transposon is a useful vector for construction of transgenic silkworms, particularly when in vitro synthesized mRNA is used. This is the first report showing that Minos can be used as a vector for germ-line transformation in lepidopteran insects.

Actins↗

PubMed2004

Transient in vivo gene delivery to the silkworm Bombyx mori by EGT-null recombinant AcNPV using EGFP as a reporter.

Several strains of silkworm Bombyx mori were tested for the gene delivery feasibility of Autographa californica nucleopolyhedrovirus (AcNPV) in vivo. In contrast to the general belief that silkworms were non-permissive to AcNPV, we found that 3 of 7 tested strains were AcNPV permissive. To dispel the physiological influence of the ecdysteroid UDP-glucosyltransferase (EGT) on the silkworm, we modified the AcNPV bacmid by disruption of that gene. Expression pattern of EGFP in tissues of silkworm larvae after injection of EGT-null AcNPV vector carrying EGFP cassette was revealed by green fluorescence and Western blot analysis. Viral DNA was detected and semi-quantified in various kinds of tissues by dot blot assay. Active recombinant virus from larval hemolymph was detectable by TCID(50). Our results indicate that some strains of silkworm were permissive to AcNPV, which could serve as a novel gene deliver tool to silkworm in vivo.

Animals↗

PubMed2005

SilkDB: a knowledgebase for silkworm biology and genomics.

The Silkworm Knowledgebase (SilkDB) is a web-based repository for the curation, integration and study of silkworm genetic and genomic data. With the recent accomplishment of a approximately 6X draft genome sequence of the domestic silkworm (Bombyx mori), SilkDB provides an integrated representation of the large-scale, genome-wide sequence assembly, cDNAs, clusters of expressed sequence tags (ESTs), transposable elements (TEs), mutants, single nucleotide polymorphisms (SNPs) and functional annotations of genes with assignments to InterPro domains and Gene Ontology (GO) terms. SilkDB also hosts a set of ESTs from Bombyx mandarina, a wild progenitor of B.mori, and a collection of genes from other Lepidoptera. Comparative analysis results between the domestic and wild silkworm, between B.mori and other Lepidoptera, and between B.mori and the two sequenced insects, fruitfly and mosquito, are displayed by using B.mori genome sequence as a reference framework. Designed as a basic platform, SilkDB strives to provide a comprehensive knowledgebase about the silkworm and present the silkworm genome and related information in systematic and graphical ways for the convenience of in-depth comparative studies. SilkDB is publicly accessible at http://silkworm.genomics.org.cn.

Animals↗

PubMed1998

The ecdysteroid UDP-glucosyltransferase gene of Autographa californica nucleopolyhedrovirus alters the moulting and metamorphosis of a non-target insect, the silkworm, Bombyx mori (Lepidoptera, Bombycidae).

The Autographa californica nucleopolyhedrovirus (AcMNPV) does not infect the silkworm and molecular studies on silkworm insusceptibility have not been performed. In cultured cells of the silkworm, the expression of viral genes has been reported. The expression of AcMNPV genes and their effect in vivo and in vitro was studied. In this study, the early gene, the ecdysteroid UDP-glucosyltransferase (egt) gene of AcMNPV, which inactivates the insect moulting hormone by sugar conjugation, was examined to determine whether it would alter the growth of the silkworm. Using wild-type (wt) AcMNPV, the egt gene deletion virus (vEGTDEL), and the virus carrying the egt promoter-lacZ cassette in vEGTDEL (vEGTZ), the egt promoter-driven expression in cultured cells and in nonproductive infection of the silkworm was characterized. Infection of cultured cells with vEGTZ at three different doses occurred in a single cell manner. When budded wt AcMNPV was injected into the fourth and fifth instar larvae, an increase in the amount of virus occurred and caused abnormal larval growth, which resulted in the prolongation or skipping of the larval instar, premature pupation, or death during the pupal stage. For infection of the fourth instar larvae, precocious metamorphosis was observed. When the same amount of vEGTDEL was injected, the alteration of growth did not occur. These results suggest that the egt gene was expressed in the primary infected cells of the silkworm, and that the EGT was secreted into the haemocoel, which significantly altered larval growth.

Animals↗

PubMed2004

Quantitative evaluation of the therapeutic effects of antibiotics using silkworms infected with human pathogenic microorganisms.

The injection of bacteria (Staphylococcus aureus, Stenotrophomonas maltophilia) or true fungi (Candida albicans, Candida tropicalis) that are pathogenic to humans into the silkworm hemolymph leads to death of the larvae within 2 days. Antibiotics used for clinical purposes have therapeutic effects on silkworms infected with these pathogens. The 50% effective doses obtained by injection into the silkworm hemolymph are consistent with those reported for mice. Injection of vancomycin and kanamycin into the silkworm hemolymph was effective, but oral administration was not. Chloramphenicol, which is effective by oral administration, appeared in the silkworm hemolymph soon after injection into the midgut, whereas vancomycin did not. Isolated midgut membranes were impermeable to vancomycin. Thus, the ineffectiveness of oral administration of vancomycin to silkworms is due to a lack of intestinal absorption.

Administration, Oral↗

PubMed2005

Genetic diversity among silkworm (Bombyx mori L., Lep., Bombycidae) germplasms revealed by microsatellites.

To determine genetic relationships among strains of silkworm, Bombyx mori L., 31 strains with different origins, number of generations per year, number of molts per generation, and morphological characters were studied using simple sequence repeat (SSR) markers. Twenty-six primer pairs flanking microsatellite sequences in the silkworm genome were assayed. All were polymorphic and unambiguously separated silkworm strains from each other. A total of 188 alleles were detected with a mean value of 7.2 alleles/locus (range 2-17). The average heterozygosity value for each SSR locus ranged from 0 to 0.60, and the highest one was 0.96 (Fl0516 in 4013). The mean polymorphism index content (PIC) was 0.66 (range 0.12-0.89). Unweighted pair group method with arithmetic means (UPGMA) cluster analysis of Nei's genetic distance grouped silkworm strains based on their origin. Seven major ecotypic silkworm groups were analyzed. Principal components analysis (PCA) for SSR data support their UPGMA clustering. The results indicated that SSR markers are an efficient tool for fingerprinting cultivars and conducting genetic-diversity studies in the silkworm.

Alleles↗

PubMed2000

Silkworm hemolymph inhibits baculovirus-induced insect cell apoptosis.

The effect of silkworm hemolymph on baculovirus-induced insect cell apoptosis was investigated. The addition of silkworm hemolymph into the culture medium either before or during the baculovirus infection increased the host cell longevity; however, its addition after the infection was less effective. This can be explained by the higher transfer rate of silkworm hemolymph which is caused by endocytosis during the virus internalization step. The delayed cell death due to silkworm hemolymph was not caused by an inhibition of the virus attachment and internalization steps. The apoptosis was analyzed using DNA fragmentation and TUNEL assays, and the resulting data confirm that silkworm hemolymph inhibits baculovirus-induced insect cell apoptosis.

Animals↗

PubMed1996

Influence of thyroxine on different ion-dependent ATPase activities in fat body of tasar silkworm, Antheraea mylitta D.

The activities of Na(+)-K(+)-, Ca(2+)-, and Mg(2+)-ATPase of tasar silkworm, Antheraea mylitta D. fat body were investigated from fifth larval stage to adult emergence after injection of various doses (0.5, 1.0, 2.0, and 5.0 micrograms/g) of mammalian thyroxine (T4) to 1-hr-old fifth instar larvae. In normal silkworms, both sexes exhibited maximum enzyme activity before spinning (Day 12). Na(+)-K(+)-, Ca(2+)-, and Mg(2+)-ATPase activities in fat body of silkworms markedly declined after pupation and more so on the 1-day-old adults. All doses of thyroxine treated on fifth instar larvae significantly altered ATPase activity in the larval, pupal, and adult stages in both sexes. ATPase activity was not altered by lower dose of T4 (0.5 micrograms/g) in 2-day-old fifth stage larvae, while the higher dose (5.0 micrograms/g) surprisingly caused a reduction in ATPase activity during the different developmental stages. The fat body ATPases were influenced by thyroxine in all the stages of silkworm in a dose-dependent manner. Our results thus indicate that thyroxine has a controlling influence on the ATPase system in silkworm fat body.

Aging↗

PubMed1988

Comparison of serum protein inhibitors from various mammals, chicken and silkworms against four proteases.

1. Protein serum inhibitors against four proteases were compared using eight mammals, chicken and silkworms. 2. The similarity of inhibition spectra and electrophoretograms was found in related mammals. 3. In the silkworm and chicken, inhibitory activities against fungal protease and subtilisin were extremely high. 4. Electrophoretic patterns of inhibitors for chymotrypsin and trypsin were very similar in mammals, but different in the silkworm, that is, mammalian inhibitors seemed to show broader protease specificity. 5. Electrophoretic bands of the silkworm inhibitors showed more dispersed molecular species than those of other animals. 6. Column chromatographic patterns of silkworm inhibitors against four proteases showed more diverse and distinct profiles than those of other animals.

Animals↗

PubMed1987

Use of the silkworm, Bombyx mori, and an insect baculovirus vector for high-level expression and secretion of biologically active mouse interleukin-3.

Using the virus vector derived from a baculovirus of Bombyx mori (Bm), we constructed an infectious recombinant virus carrying the mouse interleukin-3 (IL-3) cDNA placed downstream from the polyhedrin promoter. Silkworms infected in vivo with recombinant virus or the silkworm-derived BmN cell line infected in vitro secreted large amounts of IL-3 into hemolymph or culture medium, respectively. On a per volume basis, about 20-fold more activity was found in the culture supernatants of the infected BmN cells and 10000-fold more activity was detected in the hemolymph as compared to supernatants obtained from COS7 monkey cells transfected with plasmid pcD-IL3 using the SV40 early promoter [Yokota et al., Proc. Natl. Acad. Sci. USA 81 (1984) 1070-1074]. Three distinct species of Il-3 of molecular masses, 18, 20 and 22 kDa were produced and all were converted to a 15-kDa protein by N-glycanase digestion, indicating that silkworm cells glycosylated IL-3. The N-terminal amino acid sequences of the IL-3 purified from tissue culture medium and hemolymph were identical to that of mammalian-derived IL-3, showing that silkworm cells recognized the mammalian signal sequence and cleaved it at the correct position. The purified silkworm-produced IL-3 had biological activities indistinguishable from IL-3 produced by mammalian cells as assessed by mast-cell proliferation assays, colony-formation assays using mouse bone marrow cells, and by receptor-binding assays using [125I]IL-3.

Animals↗

PubMed2005

Efficient large-scale protein production of larvae and pupae of silkworm by Bombyx mori nuclear polyhedrosis virus bacmid system.

Silkworm is one of the most attractive hosts for large-scale production of eukaryotic proteins as well as recombinant baculoviruses for gene transfer to mammalian cells. The bacmid system of Autographa californica nuclear polyhedrosis virus (AcNPV) has already been established and widely used. However, the AcNPV does not have a potential to infect silkworm. We developed the first practical Bombyx mori nuclear polyhedrosis virus bacmid system directly applicable for the protein expression of silkworm. By using this system, the green fluorescence protein was successfully expressed in silkworm larvae and pupae not only by infection of its recombinant virus but also by direct injection of its bacmid DNA. This method provides the rapid protein production in silkworm as long as 10 days, is free from biohazard, thus will be a powerful tool for the future production factory of recombinant eukaryotic proteins and baculoviruses.

Animals↗

PubMed2005

A fibroin secretion-deficient silkworm mutant, Nd-sD, provides an efficient system for producing recombinant proteins.

The silkworm Nd-s(D) mutant is silk fibroin-secretion deficient. In the mutant, a disulfide linkage between the heavy (H) and light (L) chains, which is essential for the intracellular transport and secretion of fibroin, is not formed because of a partial deletion of the L-chain gene. To utilize the inactivity of the mutant L-chain, we investigated the possibility of using the Nd-s(D) mutant for the efficient production of recombinant proteins in the silkworm. A germ line transformation of the mutant with a normal L-chain-GFP fusion gene was performed. In the transgenic mutant, normal development of the posterior silk gland (PSG) was restored and it formed a normal cocoon. The biochemical analysis showed that the transgenic silkworms expressed the introduced gene in PSG cells, produced a large amount of the recombinant protein, secreted it into the PSG lumen, and used it to construct the cocoon. The molar ratio of silk proteins, H-chain:L-chain-GFP:fibrohexamerin, in the lumen and cocoon in the transgenic silkworm was 6:6:1, and the final product of the fusion gene formed about 10% of the cocoon silk. This indicates that the transgenic mutant silkworm possesses the capacity to produce and secrete the recombinant proteins in a molar ratio equal to that of the fibroin H-chain, contributing around half molecules of the total PSG silk proteins.

Animals↗

PubMed2005

Effects of molecular mass and hydrophobicity on transport rates through non-specific pathways of the silkworm larva midgut.

We previously reported that therapeutic drug effects in the silkworm infection model are largely influenced by midgut permeability. In this report, we describe the effects of drug molecular mass and hydrophobicity on transport through the silkworm larva midgut membrane. Hydrophilic compounds with a molecular mass of greater than 400Da did not permeate the silkworm larva midgut, and the hydrophobicity of similar-sized compounds had positive effects on the transport rate. Furthermore, we compared transport rates through the midgut membrane between cefcapene sodium (CFPN-Na) and cefcapene pivoxil (CFPN-PI), which is a CFPN-Na prodrug. The in vitro transport rate of CFPN-PI was three times faster than that of CFPN-Na. Moreover, when CFPN-PI and CFPN-Na were injected into the living silkworm larva midgut, CFPN-PI appeared rapidly in the haemolymph, whereas CFPN-Na did not. The 50% effective dose (ED50) of CFPN-PI administered via the midgut was one-sixth that of CFPN-Na. These findings suggest that the general features of the non-specific transport route are similar between silkworm larvae and mammals.

Animals↗