不同NaHCO3碱度对瓦氏雅罗鱼鳃组织结构的影响

THE EFFECT OF DIFFERENT BICARBONATE ALKALINITY ON THE GILL STRUCTURE OF AMUR IDE(LEUCISCUS WALECKII)

研究采用组织学方法观察和比较了达里诺尔湖瓦氏雅罗鱼(Leuciscus waleckii,碱水种)和松花江瓦氏雅罗鱼(淡水种)在相同碳酸盐碱度胁迫下(C_A0、C_A30和C_A50)鳃组织结构的差异,探究瓦氏雅罗鱼碱水种耐高碱特性与鳃组织结构微观调整的适应性关系。结果显示,随着碱度增加,碱水种鳃丝变宽、鳃小片变长、鳃小片间距变大(P<0.05);淡水种鳃丝变宽、鳃小片间距变大(P<0.05),鳃小片长度在C_A30时显著变长(P<0.05),而在C_A50时与对照组无明显差异(P>0.05)。碱水种在C_A30和C_A50的氯细胞数量与对照组相比明显增加,C_A50的氯细胞排列更加紧密并且有叠加现象,扁平上皮细胞变大,细胞表面增厚;淡水种在C_A30时的氯细胞数量明显多于C_A50,但在碱度胁迫下,鳃小片出现破损,扁平上皮细胞、柱细胞和血细胞融合、脱落现象严重。另外,在碱水种和淡水种鳃耙上皮细胞中发现了大量黏液细胞分泌,随着碱度增加,黏液细胞由大而稀疏变为小而密集,其中碱水种的黏液细胞数量较淡水种多,而且排列更为整齐、密集。鳃组织学研究结果表明,瓦氏雅罗鱼碱水种通过保持鳃组织结构和生理功能的完整性达到对高碱环境的长期适应,而淡水种则因鳃细胞融合、脱落造成生理功能丧失,不能长期适应高碱环境。研究结果可为淡水鱼类在盐碱水的移植驯化提供依据和指导。

In this study, the differences of branchial epithelium of Amur ide(Leuciscus waleckii) originated in Dali Nor Lake(alkal-adapled species) and Songhua River(freshwater species) were observed, which compared under the same bicarbonate stress of 0(C_A0, pH 7.56), 30 mmol/L(C_A30, pH 9.44) and 50 mmol/L(C_A50, pH 9.55) by histological method. Furthermore, the adaptive relationship between high alkali-tolerance and the micro-adjustment of gill tissue structure was explored. The results showed that the gill structure of the alkaline species changed correspondingly, with the increase of alkalinity, which the gill filament became more full, the gill lamella became longer as well as the interval between lamellae became larger compared to the control(C_A0, P<0.05). The freshwater species also changed,which the gill filament became more full and the interval between lamellae became larger(P<0.05) than the control, although the gill lamella became longer at C_A30(P<0.05), there was no significant difference between C_A50 and C_A0(P>0.05). Chloride cells were found in the base of lamellae which increased higher in both of species than that of the control, pavement cells were observed in the secondary gill lamella which became larger and thicker in alkal-adapled species than the control, whereas due to the fusion and cell detachment of pavement cells, pillar cell, and blood cells,the secondary gill lamella of fresh water species was damaged severely. In addition, a large number of mucous cells were found in the epithelium of gill raker of alkal-adapled and freshwater species. With the increase of alkalinity, the mucous cells changed from large and sparse to small and dense. Among them, the mucus cells of alkal-adapled species were more than that of freshwater species, and arranged more orderly and tightly. To sum up, the alkal-adapled species could adapt to the high alkali environment for a long time by keeping the integrity of gill structure and physiological function, while the freshwater species vice versa, because of the loss of physiological function caused by the fusion and exfoliation of gill cells. The results of this study can provide basis and guidance for transplantation and acclimation of freshwater fish in saline and alkaline water in the future.