Biochemical characterization of the microsporidian Nosema bombycis spore proteins

Spore proteins of the microsporidian Nosema bombycis, from the silkworm Bombyx mori, were analysed by SDS–polyacrylamide gel electrophoresis. The protein profile of partially solubilized spores showed three major peptide bands of molecular weight 68, 94 and 100 kDa. On complete solubilization, it showed peptide bands ranging from 17 to 68 kDa. Attempts to purify the 17 kDa infection-specific protein showed aggregation of this protein to higher molecular size proteins. Partial peptide analysis of the different peptides exhibited similar patterns suggesting the probablity of processing during the infective cycle. Reconstitution assay showed the reversible nature of this processing. N-terminal sequencing showed homology to heat shock proteins. The low molecular weight 17 kDa protein also showed very high protease activity.     

Immunological characterization of spore proteins of the microsporidian Nosema bombycis

The spore proteins of the microsporidian, Nosema bombycis, from the silkworm, Bombyx mori were analysed by SDS–polyacrylamide gel electrophoresis. The western blot analysis using total antibodies showed major antigenic peptides of sizes 94, 68, 45, 31, 28, 17 and 12.5 kDa. Immunological cross reaction was observed when the antibody raised against the infection-specific 17 kDa protein was used for western blotting. Antigenic relatedness among the different polypeptides was seen. Enzymatic analysis of the immunodominant structures of the antigen showed that carbohydrates and proteins are the major components of the epitopes, with lipids also making a small contribution. The relative epitope densities among the different polypeptides reveal that the antigens consist of multiple similar epitopes which are probably conformational epitopes.     

Studies on the utilization of single cell protein by the silkworm Bombyx mori

Final-instar larvae of Bombyx mori fed mulberry leaves, supplemented with Spirulina fusiformis (Woronichin) as a source of single cell protein (SCP), required 6 days to attain a maximum larval weight of 2090 mg; control group larvae needed 9 days to attain a final larval weight of 1470 mg. Quantity of feeding, assimilation and conversion efficiencies increased substantially in the SCP-fed group. Significant improvements in the economic characters such as cocoon, pupal, and shell weights were obtained in the SCP supplemented larvae in comparison to the normal leaf fed larvae. About 15% of the labelled S. fusiformis was directly incorporated into larval tissue. Presence of SCP in the gut facilitated better conversion of consumed leaf protein.

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Etudes sur l'utilisation des protéines de cellules isolées par le ver à soie, Bombyx mori

Résumé Des chenilles du dernier stade de Bombyx mori, alimentées sur mûrier additionné de Spirulina fusiformis comme source de protéine de cellule isolée (SCP), atteignent en 6 jours le poids larvaire maximum de 2090 mg; les chenilles témoins consommaient pendant 9 jours pour obtenir leur poids larvaire final de 1470 mg. Les quantités consommées, les coefficients d'assimilation et de conversion ont augmenté substantiellement chez les chenilles avec SCP. Des augmentations significatives de critères économiques, comme les poids de cocon, de nymphe et de cogul, ont été observées avec l'addition de SCP par rapport aux témoins. Environ 15% du S. fusiformis marqué a été incorporé directement dans les tissus larvaires. La présence de SCP dans l'intestin a permis une meilleure conversion des protéines foliaires consommées.

     

Dimethyl sulfoxide inhibits the expression of early growth-response genes and arrests fibroblasts at quiescence

We have previously shown that dimethyl sulfoxide (DMSO) treatment of mouse embryo fibroblasts (MEF) at the early hours of mitogenic stimuli resulted in the inhibition of DNA and protein synthesis; delayed treatment of serum-stimulated cells with DMSO had little effect on the synthesis of these macromolecules. Here, we demonstrate the specific inhibition of expression of early growth response genes by DMSO in serum-stimulated MEF. The expression of interleukin 6, and of oncogenes c-myc and c-fos were inhibited when the cells were treated with 2% DMSO from the beginning of serum-stimulated growth but not after 3 h of mitogenic stimuli. Although the actin gene is an early serum-response gene, its expression was not affected by DMSO. The synthesis of another serum-induced protein, the plasminogen activator inhibitor-1 was blocked during concurrent and delayed (after 3 h of stimulation) treatment of serum-stimulated fibroblasts with DMSO. The expression of glyceraldehyde-3-phosphate dehydrogenase gene was not affected by DMSO. These results indicate that the expression of non-growth-related genes are either not affected or affected nonspecifically both at early and late stages of serum-induced growth of mouse embryo fibroblasts. The serum-induced expression of c-fos gene was abolished by DMSO treatment of MEF while the phorbol 12-myristate 13-acetate-induced expression of fos gene was not, indicating that the PMA signaling pathway was refractory to DMSO. Treatment of cells with medium containing 2% DMSO for 24-48 h prevents them from progression into cell cycle by preventing the expression of genes involved in G0-G1 transition of quiescent cells.     

Preliminary genomic characterization of microsporidian Nosema bombycis

In order to characterize the genome of Nosema bombycis, the techniques of karyotyping, pulsed field gel electrophoresis, and polymerase chain reaction were applied. Nosema genomic DNA moved as 23 kb fragment on a standard agarose gel. The karyotype showed four chromosomes, the molecular karyotyping by pulsed field gel electrophoresis also showed four chromosomes. Arbitrarily primed polymerase chain reaction (PCR) with various primers showed amplification products of sizes ranging from 1.6 to 0.15 kb. Polymerase chain reaction with specific primer showed an amplification product of approximately 315 nucleotides. The DNA hybridizations are discussed. This is the first report of its kind on microsporidian Nosema bombycis. The current data can play a major role in elucidating the molecular biology of this parasite. This revised version was published online in July 2006 with corrections to the Cover Date.