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Long-term exposure of human sperm cells to reactive oxygen species (ROS) can cause decreased motility and viability, as well as DNA fragmentation. An antioxidant defense system, called a preventive antioxidant system, is therefore needed to maintain low ROS concentrations in sperm and seminal plasma. Superoxide dismutase (SOD, EC 1.15.1.1), one of the most important antioxidant enzymes, catalyzes the conversion of superoxide radical (O2•-) to hydrogen peroxide (H2O2) and molecular oxygen (O2). In this report, we documented a high SOD activity level in the reproductive organs of the male silkmoth (Bombyx mori, L.), particularly in the glandula lacteola, and found that about 90% of the SOD activity was transferred to females by ejaculation and maintained. We characterized three cDNAs from the adult male reproductive system: a soluble cytoplasmic copper/zinc SOD (Cu/Zn SOD, SOD1) and two extracellular forms of copper/zinc SOD (EC-SOD, SOD3). The levels of transcription and protein accumulation of Bombyx SOD1 indicated that it is abundantly present in the extracellular fluid of the male glandula lacteola, which transfers to the female during ejaculation. Furthermore, it was observed that some of the transferred SOD1 exists in the sperm fraction stored in the mating female's bursa copulatrix. Our present results demonstrate the origins of seminal SOD activities and suggest that SOD might be a potential source and function of antioxidants in semen and also may control the amount of extracellular ROS involved in sperm quality maintenance. [ABSTRACT FROM AUTHOR]

Ecdysone oxidase (EO) is an enzyme that catalyzes the oxidation of ecdysteroids, the molting steroid hormones in insects. This enzyme may play important roles in the conversion of ecdysteroids to 3-dehydroecdysteroids. In this study, we identified a novel EO, designated bmEO2, from the silkworm, Bombyx mori. A cDNA encoding bmEO2 was cloned by employing the reverse transcriptase-polymerase chain reaction (PCR) technique. The deduced amino acid sequence of bmEO2 showed conserved residues and sequence homology to other known insect EOs and glucose dehydrogenase proteins. Quantitative real-time PCR revealed that the bmEO2 transcript was abundantly present in larval testes of B. mori. [ABSTRACT FROM AUTHOR]

cDNA that encodes a sigma class glutathione S-transferase (GST; bmGSTS2) from the silkworm (Bombyx mori) was cloned by reverse transcriptase polymerase chain reaction and sequenced. The deduced amino acid sequence revealed 68%-63% identity with the sigma class GSTs from other insects. bmGSTS2 mRNA was widely distributed in various tissues. The recombinant enzyme was functionally overexpressed as a soluble form in Escherichia coli, purified to homogeneity and characterized. The optimum pH of bmGSTS2 was approximately pH 7.0 and bmGSTS2 retained >75% of its original activity after incubation for 12 h at pH 6.0-8.0. Incubation for 30 min at temperatures below 40°C did not affect the enzymatic activity. bmGSTS2 was able to catalyze the reaction of glutathione with hydrogen peroxide and 4-hydroxynonenal. These results indicate that bmGSTS2 may play a role in antioxidant defense in the silkworm. [ABSTRACT FROM AUTHOR]

Cytosolic sulfotransferases (SULTs) are enzymes that play important roles in the detoxification of xenobiotics, as well as in the modulation of endogenous compounds such as steroid hormones by sulfation. In this study, we identified a novel SULT, designated bmSULT, from the silkworm, Bombyx mori. A cDNA encoding bmSULT was cloned by employing the reverse transcriptase-polymerase chain reaction technique. The deduced amino acid sequence of bmSULT showed conserved residues and sequence homology to known SULTs. Quantitative real-time PCR revealed that bmSULT mRNA was abundant in the larval midgut and pupal fat body of B. mori. [ABSTRACT FROM AUTHOR]

Arginase is an oligometric protein that catalyzes the conversion of arginine to ornithine and urea in the presence of metal. Arginase in the silkworm, Bombyx mori, has been shown to participate in sperm maturation. In this study, we examine the enzymatic properties of B. mori arginase identified previously. The recombinant enzyme (bmArg-r) was purified to near homogeneity by ammonium sulfate fractionation, anion-exchange chromatography and gel-filtration chromatography. The isolated bmArg-r exhibits activity toward arginine in the presence of manganese ions, whereas it was unable to catalyze lysine hydrolysis. Copper and magnesium ions did not accelerate the activity toward arginine. Mutagenesis of His107 in the metal-binding site of bmArg-r revealed that this residue is important for enzymatic function. We found that the mutation of His132, another histidine residue present in the metal-binding site, reduced the solubility of recombinant bmArg-r. It was considered that these histidine residues located in the metal-binding site of bmArg-r play a crucial role in catalytic activity. [ABSTRACT FROM AUTHOR]

The article presents a study that determines the purification and characterization of cocoonase (CCN) from the silkworm Bombyx mori. It describes the process of the study that observes the potential of Hydrogen (pH) of the CCN during purification. It also outlines the findings of the study which suggests that typical trypsin inhibitors were shown in CCN, however, its relative inhibitory activities were lower than those against bovine trypsin.

The article discusses salt-induced changes in the subunit of Bacillus stearothermophilus lipoate acetyltransferase (E2). It mentions that E2 is composed of sixty identical subunits and each subunit had three domains including a lipoyl domain (LD), a catalytic domain (CD), and a peripheral subunit-binding domain (PSBD). It further states that large amount of potassium chloride (KCl) converted E2 into aggregative complex ( CA).

We examined which proteins were enhanced in the silkmoth in response to its exposure to insecticides. We previously found that the levels of four cytochrome P450s (CYPs) were higher following insecticide exposure (Yamamoto et al., 2010). In this study, we focused on other mRNAs encoding the silkmoth CYP proteins (CYP6B29, CYP18A1, CYP366A1, CYP302A1) induced mRNA expression analysis revealed that each CYP mRNA was expressed in a tissue-specific manner and that expression was developmentally regulated. Quantitative PCR revealed that these CYP mRNAs were upregulated in the larval fat body after exposure of the silkmoth to various insecticides. Our results suggest that the CYPs can contribute to insecticide resistance in Lepidopterans. [ABSTRACT FROM AUTHOR]

The article discusses a study which identified amino acid residues Asp103, Ser162, and Ser166 of unclassified glutathione transferases (GSTs) from Bombyx mori. Topics discussed include an overview of GSTs, the examination of two motifs which are the small hydrophobic core and ionic bridge, and the interaction of a key residue Phe104 with a hydrophobic region.