Oxidative stress and spermatogenesis suppression in the testis of cadmium-treated Bombyx mori larvae.

Bombyx mori L. (B. mori) were exposed to cadmium chloride (CdCl2) incorporated in an artificial diet (0, 6.25, 12.5, 25, and 50 mg kg(-1)) throughout the larval stage. Changes in malondialdehyde (MDA) and reduced glutathione (GSH) contents and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as their corresponding messenger RNA (mRNA) levels in the testes of the fifth instar larvae were evaluated. Additionally, spermatozoon deformation in the testes was examined. Upon Cd treatment, the MDA content in the testes was significantly increased in a concentration-dependent manner. Cd-exposed larvae had increased levels of glutathione. Pearson's correlation analysis revealed that SOD and CAT activities were positively correlated (R (2) = 0.605, P = 0.017). The changing trends in the mRNA levels of these enzymes were not always consistent with those of enzymatic activities. Alterations in GSH-Px activities and mRNA levels were positively correlated (R (2) = 0.771, P < 0.01). Morphological analysis revealed that Cd deformed and affected the maturation of spermatozoa. Our results collectively support a relationship between Cd and alterations in the levels of antioxidant enzymes in B. mori testes.

[Characterization and phylogenetic analysis of the cytochrome oxidase subunit I gene of mitochondrial genome from Takifugu fasciatus].

The Takifugu fasciatus mitochondrial cytochrome oxidase I gene (COI) and its associated tRNA genes were sequenced by PCR. The open reading frame of COI gene contains 1,546 bp nucleotides, encoding a putative protein of 515 amino acid residues. The pattern of codon usage of the COI gene is less biased toward A+T. The COI gene of T. fasciatus shows a high degree of homology with that from the other 14 fish species recorded in the GenBank and has 97.6% homology with Takifugu rubripes, 76.5% with Masturus lanceolatus and 75.4% with Mola mola. The phylogenetic trees show that the relationships based on the homology is consistent with the morphological and taxonomic results. Predicted secondary structures of the tRNA genes suggest that they have the classical cloverleaf structures.