Enhanced Resistance of Triploid Crucian Carp to Cadmiuminduced Oxidative and Endoplasmic Reticulum Stresses.

BACKGROUND: Cadmium is a major heavy metal pollutant. Even at low concentrations in waste water Cadmium can accumulate in algae and sediments, and it is absorbed by both plants and aquatic animals, like shellfish and fish. Triploid crucian carp is an important economic fish, and have been farmed on a large scale in China. OBJECTIVE: to explore the molecular mechanisms underlying Cadmium stress of triploid crucian carp. METHOD: we applied following experimental method to conduct research: transcriptomes analysis, histological observation, Quantitative real-time PCR and enzyme activity analysis et al. Results: in the present study, we obtained following important results: 1) Under Cd stress, the mortality and abnormality rates in triploid crucian carp were lower than those of diploid strains and the effects of Cadmium treatment on the liver were revealed by histological observation; 2) the liver transcriptomes of triploid crucian carp were obtained and the data was analyzed; 3) 14 genes related to algae and sediments stress were screened from transcriptome data, and the expression of these genes was verified by Quantitative real-time PCR. The results were consistent with the gene results in transcriptome data; 4) Quantitative real-time PCR and enzyme activity analysis all confirmed triploid crucian carp resistance to Cadmium stress was regulated by both oxidative stress and ER stress responses; 5) We found that IRE-1 and PERK, not ATF- 6, were involved in the enhance Cadmium resistance of triploid crucian carp. CONCLUSION: these studies demonstrate that triploid crucian carp have strong resistance to Cadmium.

A light-colored region of caudal fin: a niche of melanocyte progenitors in crucian carp (Cyprinus carpio L.).

Melanocyte stem cells are a population of immature cells which sustain the self-renewal and replenish the differentiated melanocytes. In this research, a light-colored region (LCR) is observed at the heel of caudal fin in juvenile crucian carp. By cutting off the caudal fin, the operated caudal fin can regenerate in accordance with the original pigment pattern from the retained LCR. As markers of stem cells, Oct4 and Sox2 have been found to be highly expressed in the LCR as well as Mitfa, a label of the melanoblasts. In vitro, Mitfa+ melanoblasts are observed in the cells which are derived from the LCR and transfected with Mitfa-EGFP reporter by using Tol2 transposon system. Furthermore, by real-time qPCR, it is shown that the level of sox2 mRNA is gradually decreased from the LCR to proximal and distal caudal fin, and that of mitfa mRNA in the proximal caudal fin (PCF) is higher than that in the LCR, while it is the lowest in the distal caudal fin. Hence, we propose that the LCR is a pigment progenitor niche, sending melanocytes to the distal of caudal fin, which gradually emerges as caudal fin grow. We reveal that the LCR of caudal fin might be a niche of pigment progenitors, and contribute to pigment-producing stem cells in crucian carp.