Identification of a warm‐temperature acclimation‐associated 65‐kDa protein encoded by a temperature‐ and infection‐responsive gene in the Kumgang fat minnow Rhynchocypris kumgangensis

Abstract

Water temperature is one of the most important factors in fish physiology; thus, it is important to identify genes that respond to changes in water temperature. In this study, we identified a warm- temperature acclimation-associated 65-kDa protein (Wap65) in the Kumgang fat minnow Rhynchocypris kumgangensis, a small, cold-freshwater fish species endemic to Korea. Kumgang fat minnow Wap65-1 (kmWap65-1) was cloned using polymerase chain reaction (PCR)-based strategies, and was found to be highly homologous with teleost Wap65-1 and mammalian hemopexin, a heme-binding protein that transfers plasma heme into hepatocytes. kmWap65-1 mRNA was expressed mainly in the liver and its expression levels were significantly increased by both short- and long-term exposure to high temperature, which was evaluated by real-time quantitative PCR. Furthermore, the expression levels of kmWap65-1 were highly elevated by exposure to bacterial lipopolysaccharide. These results indicate that kmWap65-1 expression is associated with environmental stresses such as increases in water temperature and bacterial infection. J. Exp. Zool. 325A:65-74, 2016. © 2015 Wiley Periodicals, Inc.

Identification of warm temperature acclimation‐associated 65‐kDa protein‐2 in Kumgang fat minnow Rhynchocypris kumgangensis

“…In a previous study, we isolated Wap65‐1 from Kumgang fat minnow (kmWap65‐1) and demonstrated sensitivity of the gene to temperature changes and bacterial infection (Im et al., ). Here, we identified an isoform of kmWap65 in liver tissue of the fish, designated kmWap65‐2, and compared the expression profiles of both genes in response to physiological stress stimuli, including temperature changes, bacterial infection, and exposure to environmental toxin.…”

“…We isolated kmWap65‐2 complementary DNA (cDNA) from liver tissue of Kumgang fat minnow as described previously (Im et al., ). Briefly, total RNA was isolated and reverse‐transcribed.…”

“…The methods used for fish collection and water temperature control have been described previously (Im et al., ). Briefly, adult Kumgang fat minnows (average length 7.276 ± 0.768 cm, weight 3.141 ± 0.922 g) were collected from streams in Inje‐gun, Gangwon‐do, Republic of Korea.…”

“…Warm temperature acclimation‐associated 65‐kDa protein (Wap65) was initially isolated from goldfish muscle and hepatopancreatic tissue (Kikuchi, Yamashita, Watabe, & Aida, ). Wap65 protein activation has been reported in response to various physiological stresses including temperature acclimation (Kinoshita, ; Sha et al., ; Im, Kwon, Kong, & Ghil, ), immune response (Peatman et al., ; Sarropoulou et al., ; Shi et al., ), and heavy metal exposure (Aliza, Ismail, Kuah, Shu‐Chien, & Tengku Muhammad, ). Wap65 also contributes to fish development (Hirayama, Kobiyama, Kinoshita, & Watabe, ; Nakaniwa et al., ; Sarropoulou et al., ).…”

“…We therefore believe that it will be important to undertake long‐term monitoring of physiological stresses in the fish and to develop biomarkers that can assess their physiological status. In a previous study (Im et al., ), we isolated the Wap65‐1 gene from liver tissue of Kumgang fat minnow (designated kmWap65‐1). The sequence of this gene was highly homologous to those of teleost Wap65‐1 and mammalian hemopexin.…”