The anti-diabetes mechanism of silkworm Bombyx mori L. powder and extracts was found to inhibit the activity of α-glycosidase. The major functional component of silkworm powder was 1-deoxynojirimycin (1-DNJ), which exerts a blood glucose-lowering effect. In this study, we aimed to compare the effects of the supplements, including red ginseng extract on the functional components of silkworm. Fifty silkworm larvae were divided into the control group (Con, N=50), group A (A, artificial diet 95% and mulberry leaf powder 5%), group B (B, artificial diet 95% and mulberry powder 5%), group C (C, artificial diet 95% and Rubus coreanus remainders 5%), group D (D, artificial diet 95% and red ginseng extract 5%), and group E (E, artificial diet 95% and yeast powder (Saccharomyces cerevisiae). Body weights and length of silkworm larvae showed significant improvement in group A, D. In particular, the growth rate in group D (artificial diet 95% and red ginseng extract 5%) was larger than that of Con. In addition, the results showed that 1-DNJ concentration was significantly largest in group D. From these results, it is concluded that the addition of red ginseng extract may be effective for larval growth and 1-DNJ accumulation in silkworm rearing with an artificial diet.

The silkworm (Bombyx mori), as an industrial insect, possesses a high economic value. Casual discrimination and accumulated genetic information of silkworm varieties are essential ground for the practical utilization and long-term conservation. In this study, nine available microsatellite loci were successfully genotyped from ~50 silkworm strains preserved in Korea. According to genotyping analysis, we obtained 3 ~ 16 alleles per locus, with an average of 7.4, the observed heterozygosity ranging from 0.04 to 0.98, and the polymorphic information content (PIC) ranging from 0.06 to 0.88, revealing that some loci are highly variable. Among 54 strains 13 strains were casually identified by the presence of 17 strain-specific apomorphic alleles. Furthermore, 30 among remaining strains contained strain-specific allele combinations that are also apomorphic to each strain, allowing us to discriminate each of these from other strains by genotyping of multiple loci. These results collectively suggest that the silkworm microsatellite DNA is actually and potentially important molecular marker for the discrimination of the silkworm strains that are preserved as hundreds in Korea, as more loci are genotyped.

MicroRNAs (miRNAs) are endogenous non-coding genes that participate in post-transcription regulation by either degrading mRNA or blocking its translation. It is considered to be very important in regulating insect development and metamorphosis. Insects are the largest group of animals and are extremely valuable in biological and agriculture research. Insects are also important pests to human health and agriculture, and efforts are necessary protect both humans and plants from disease and damage. Despite their importance, insects lag behind mammals, nematodes, and plants in miRNA research. At present, only 279 insect miRNAs have been identified from Drosophila melanogaster, Anopheles gambiae, Apis mellifera, Bombyx mori, and D. pseudoobscura in miRBase, and most of these miRNAs were computationally predicted without experimental validation. Functional analysis of insect miRNAs has only been conducted in D. melanogaster.

Recently Transgenesis was achieved in Bombix mori. For stable and effective transgenesis in B.mori, B.mori cytoplasmic actin gene (BmA3) promoter was used to expression of marker gene, the green fluorescent protein(GFP). Green fluorescent protein expression for selection of transformants was visible in all larval, pupal, and adult tissues but, unexpectdly, was not detectable in embryos. So, it spend times and money on rearing of silkworm. Furthermore, the BmA3 promoter is predominantly active in the midgut, which makes it difficult to reliably identify transformants since autofluorescence of many insect foods can mask low-level fluorescence and only allows the detection of strongly expressing individuals with potentially multiple insertions. Therefore, we need more intensely promoter than BmA3 promoter for selected by expression of GFP in embryos and selected by reliable expression of GFP in larvae. We performed dot blot hybridization to develop strong promoter. Nine differentially expressed clones were isolated and we focused one clone of them which has high similarity with heat shock protein 70 gene from D.melanogaster. We named it as bHSP70 (Bombyx mori heat shock protein 70). Expression from the hsp70 promoter was strong and heat shock-dependent. And Drosophila hsp70 promoter appears useful for regulating expression of Exogenous DNA. So, we analyzed transcriptional activity of promoter with bHSP70 gene by using dual luciferase assay system. bHSP70 promoter has about 264 folds more intensely than BmA3 promoter. Also, when bHSP70 promoter treated heat shock(42℃), transcriptional activity incresed 2 times more than normal condition. Therefore, we suggest that bHSP70 promoter is more effective candidate for stable transformation and selection of transformants.

Metamorphosis is a development process involving the programmed cell death of obsolete larval organs. Aspartic proteinase cathepsin D (BmCatD) is involved in the silkworm Bombyx mori metamorphosis. Here we show a novel functional role of cysteine proteinase cathepsin B during B. mori metamorphosis. The B. mori cathepsin B (BmCatB) was expressed in the fat body, epidermis, ovary, testis, and hemocyte of the larval and pupal stages. The BmCatB was ecdysoneinduced, expressed in the fat body of the molting, the final larval instar and pupal stages, and its expression led to programmed cell death. RNA interference (RNAi)-mediated BmCatB knock-down inhibited the programmed cell death of larval and pupal fat body, resulting in the arrest of larval-pupal transformation. BmCatB RNAi is up-regulated the expression of BmCatD. Based on these results we concluded that BmCatB is critically involved in the histolysis of the larval and pupal fat body, indicating that BmCatB and BmCatD are mutally regulated during silkworm metamorphosis.

SAGE technique is a sequenced-based approach that identifies which genes are expressed and quantifies their level of expression. The SAGE catalog of gene expression for a given cell or tissue is defined as the 'transcriptome'. With a goal of obtaining a set of quantitative information of expressed genes of posterior silk gland (PSG) of silkworm, we have generated a SAGE tag library from the PSGat day 4 of 5th instars of Bombyx mori. In this study, atotal of 2,406 tags were identified, representing 682 unique transcripts. Of these SAGE tags, 1,982 tags were detected twice or more accounted for 82% of the total tag population, whereas 445 tags were detected only once accounted for 18% of the total tag population. Four percent (27 tags) of the unique tags were detected at least ten times each, which corresponds to a representation of more than 53% of the total tag population. In addition, we have discussed a comparative aspect of the transcript abundance between expressed sequenced tags (ESTs) and the SAGE tags.

The efficiency to detect mutagenicity of the system using a specific locus mutation of Bombyx mori was examined and improved. In the system, mutagenicity could be detected by the egg colour manifested by the pe and/or re genes, which is a kind of recessive visible mutation of the insect. Among tested four mutagens, MMC had specially high sensitivity in the oocytes of silkworm and EMS had in the spermatozoa. PCB and dioxin showed a positive effect in both the oocytes and spermatozoa. In a consequence of sensitivity of mutagen by mating number of male moth of B. mori, treated mutagen, there was no difference between one mating - and three mating - male moth in sensitivity of mutagen. Sun3ho, B. mori variety, which showed high sensitivity to mutagens was improved in the major characteristics by crossing of C5 and N12.