Molecular cloning and expression of a cDNA encoding the luciferase from the firefly, Pyrocoelia rufa

To clone a cDNA encoding the luciferase of the firefly, Pyrocoelia rufa, we have constructed a cDNA library and isolated the luciferase gene using PCR with gene specific primers. Sequence analysis of the cDNA encoding the luciferase of P. rufa revealed that the 1647 bp cDNA has an open reading frame of 548 amino acid residues. The deduced amino acid sequences of the luciferase gene of P. rufa showed 98.9% homology to that of P. miyako. Phylogenetic analysis further confirmed the deduced amino acid sequences of the P. rufa luciferase gene belonged to the same subfamily, Lampyrinae. Southern blot analysis suggested possible presence of the P. rufa luciferase gene as a single copy and Northern blot analysis confirmed light organ-specific expression pattern at the transcriptional level. The cDNA encoding the luciferase of P. rufa was expressed as a 69 kDa band in baculovirus-infected insect cells and the recombinant baculovirus-infected cell extracts emitted luminescence in the luciferase activity assay.

Tissue-/stage-dependent expression of a cloned Bombyx mandarina QM homologue

QM, a novel gene that was firstly isolated as a putative tumor suppressor gene from Wilms' tumor cell line. Although it is well known that the QM gene product plays an important role within the tumor cells, the precise role of QM in the non-tumor cells has remained elusive. With in this mind we isolated a cDNA encoding QM homologue from Bombyx mandarina to understand the function of QM. The 596 bp cDNA has an open reading frame of 219 amino acids and a predicted mol. wt. of 25 kDa. The protein has more than 88% amino acid sequence identity to the QM protein from Drosophila melanogaster. mRNA expression gradually increased from 1-2 days after egg laying to 2 days of finial instar, while very low expressions were detected for either the pupae and the moth stages. The organs, posterior/middle division of silkgland, midgut, fat body and malpighian tubes, also show relatively high mRNA expression levels, respectively. The high degree of conservation and expression of the B. mandarina QM homologous suggest that it has a selectively conserved amino acid sequence due, presumably, to an important biological role which is associated with pupae formation.

Molecular genetic relationships between Bombycidae and Saturniidae based on the mitochondria DNA encoding of large and small rRNA

The phylogenetic relationships between Bombycidae (Bombyx mori and Bombyx mandarina) and Saturniidae (Antheraea yamamai and Antheraea pernyi) were investigated based on large and small mitochondiral rRNA genes. About 430 bp of four kinds of PCR-amplified fragments were sequenced and aligned. For the 16S rRNA gene, B. mori shared a 98, 87 and 86% sequence homology with B. mandarina, A. yamamai and A. pernyi, and for the 12S rRNA gene, B. mori shared a 99, 89 and 88% sequence homology with B. mandarina, A. yamamai and A. pernyi, respectively. DNA sequence data were also used for a phylogenetic analysis. All of the trees showed monophyly for both Bombycidae and Saturniidae. The monophyly confidence limits of these trees were estimated using bootstrapping tests and measured more than 99% for all trees for both Bombycidae and Saturniidae.

Molecular cloning and characterization of a cDNA encoding a transferrin homolog from Bombyx mori

We isolated a cDNA representing a message that was strongly induced by injection with E. coli in Bombyx mori. The 2160 bp cDNA has an open reading frame of 644 amino acids and the deduced product a predicted molecular mass of 71 kDa. The cDNA sequence shared high homology with the transferrins known so far, and its deduced peptide had unique features of transferrins, that is, sites of cystein residues and iron binding. We suggest that the B. mori transferrin plays an important role in the self-defense system.

The comparative molecular study between Bombycidae and Saturniidae based on mtDNA RFLP and cytochrome oxidase I gene sequences: implication for molecular evolution

The phylogenetic relationships between Bombyx mori and Bombyx mandarina species of Bombycidae, and Antheraea yamamai and Antheraea pernyi species of Saturniidae were investigated based on mtDNA RFLP and cytochrome oxidase I gene. The sizes of the mtDNA of all the species were estimated at approximately 16 kbp +/- 500 bp by total length of all the restricted fragments and no variation in size was recognized. Of the fourteen different restriction endonucleases used, BamHI, HindIII, PstI, EcoRI and XbaI showed RFLP. Among these, only HindIII showed RFLP between B. mori and B. mandarina. A comparative analysis of sequences was also conducted with the mitochondrial cytochrome oxidase I genes of each species. The results indicated that B. mori shared a 97%, 85% and 87% sequence identity with B. mandarina, A. yamamai and A. pernyi, respectively. B. mandarina shared a 87% and 88% sequence identity with A. yamamai and A. pernyi, respectively. A. yamamai shared 92% sequence identity with A. pernyi. The results of the phylogenetic analysis exhibited monophyly and confidence limits of more than 99% in all trees for both Bombycidae and Saturniidae.