Molecular characterization and upregulation of cytosolic manganese superoxide dismutase by imidazole derivative KK-42 in Macrobrachium nipponense.

Imidazole derivative KK-42 is a well-known regulator of insect growth. KK-42 pretreatment has been shown to promote the survival of Macrobrachium nipponense infected with Aeromonas hydrophila, possibly via activation of superoxide dismutase (SOD). In this study, the cytMnSOD gene was cloned from the hepatopancreas of M. nipponense using the rapid amplification of cDNA ends technique. The full-length cDNA of cytMnSOD was 1233 bp long, and the open reading frame was 858 bp long, encoding a 286-aa protein with a 60-aa leader sequence. The calculated molecular mass of the translated cytMnSOD protein was 31.33 kDa, with an estimated isoelectric point of 5.62. cytMnSOD contained two N-glycosylation sites, four conserved amino acids responsible for binding manganese, and a manganese SOD domain (DVWEHAYY). Real-time RT-PCR analysis showed that cytMnSOD was expressed in all tissues examined with the highest expression observed in the hepatopancreas. Levels of the cytMnSOD transcript in the hepatopancreas were highest in stage C of the molting cycle. Real-time PCR analysis revealed that cytMnSOD expression increased significantly 3, 6, and 12 h after KK-42 treatment, with simultaneous increases in SOD activity from 6 to 12 h. Our results demonstrate that cytMnSOD expression and SOD activity may be induced by KK-42, which may represent one of the molecular mechanisms through which KK-42 promotes increased survival of prawns infected with A. hydrophila.

Expression of N-cadherin in myocardial tissues during the development of a rat heart.

We investigated the expression and distribution of N-cadherin during the development of a rat heart. Immunohistochemistry (IHC) was performed to detect the expression and distribution of N-cadherin in the myocardial tissues of rats at embryonic day 18 (E18d), postnatal day 5 (P5d), postnatal day 19 (P19d), postnatal day 40 (P40d), and postnatal year 1 (P1y). Reverse transcription polymerase chain reaction was used to determine mRNA expression levels of N-cadherin in the myocardial tissues at E18d, P5d, P19d, P40d, and P1y. The IHC results showed that at E18d N-cadherin was dispersedly distributed both on the cell surface and in the cytoplasm of the myocardial cells, and gradually became concentrated at the end-to-end intercalated discs of the cardiomyocytes from birth through immaturity. In the young, middle-aged, and old rats, N-cadherin was typically distributed at the intercalated discs at the end of the myocardial cells. No significant differences in the mRNA expression levels of N-cadherin were detected in the myocardial tissue of rats at E18d, P5d, P19d, P40d, and P1y. During the development of the rat heart, observable changes in the distribution of N-cadherin occurred in the myocardial tissues, but there were no detectable changes in the expression of N-cadherin, indicating that N-cadherin is indispensable to maintaining the physical structure and function of the heart.