For the purposes of this paper, stress may be defined as any modification of environmental parameters that leads to a response by biological organisms. Stresses that affect biological structures may be non-thermal, such as ultraviolet radiation, pH, or salinity, or thermal. Temperature is one of the major stresses that all living organism face. The major effects of cold shock are decrease of membrane fluidity and the stabilization of secondary structures of RNA and DNA in the cells, which may effect the efficiency of translation, transcription, and DNA replication. In this study in compliance with the cold temperature stress about selection of the useful gene is contents from the silkworm which is been revealed. The survival rate which is caused by with the cold temperature stress until 12 hours was 100% in 0℃, until 2 hours was 100% in -5℃. A total of 960 clones were randomly selected from the subtraction cDNA library, and then performed a differential display hybridization analysis with forward and reverse probes. In conclusion, selected 53 partial clones and novel 2 full-length clones were identified as differential expressed genes. We assumed that the novel gene related with transmembrane.

Cecropin is an antimicrobial peptide that is synthesized in fat body cells and hemocytes of insect in response to a hypodermic injury or bacterial infection. A 503 bp cDNA encoding a cecropin-like antimicrobial peptide was isolated by employing annealing control primer (ACP)-based differential display PCR and 5'-RACE from immunized Papilio xuthus larvae. The open reading frame (ORF) of isolated cDNA encoded a 63 amino acid prepropeptide with a putative 22-residue signal peptide, a 3-residue propeptide and a 38-residue mature peptide with a theoretical mass of 4060.89 Da. The deduced amino acid sequence of peptide showed significant identities with other Lepidopteran cecropins. This peptide was named as papiliocin. RT-PCR revealed that the papiliocin transcript was detected at significant level after injection with bacterial lipopolysaccharide (LPS). Based on the deduced amino acid sequence of papiliocin, a 38-mer mature peptide was chemically synthesized by Fmoc method, and analyzed antimicrobial activity. The synthetic papiliocin peptide had a broad spectrum of activity against fungi, Gram-positive and negative bacteria, and also showed no hemolytic activity against human red blood cell.

Electroporation is well known today as a powerful transfection technique and is useful for the study of gene expression. The advantage of the electroporation method is that large quantity of silkworm (Bombyx mori) eggs can be transformed in a very short time. However, how to use it for introducing foreign gene into silkworm eggs needs systematical investigation. In our silkworm transgenesis program, we needed an efficient technique to evaluate the functionality of transgenes before their injection into eggs. The goal of this experiment was to find an alternative efficient method of generating transgenic silkworm eggs using a commercially available electroporation device. The Gene Pulser Xcell (Bio-Rad Laboratories, USA) were used. In contrast to other electroporation devices, which are based on a single pulse with exponential decay or square wave technology. We investigated pigmentation-rate and hatching-rate of the silkworm eggs of electroporation. We used foreign gene LacZ, EGFP, Ds-red induced vector system with selection marker for transgenic silkworm. The LacZ gene in 3rd instar larva DNA can be detected by β-galactosidase stain. During these technical studies we found that optimizing parameters such as electrical voltage, number of pulses and their frequency, and conductivity of the buffer was important. These results confirmed that electroporation is available technique for transfecting B. mori egg.

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.