CAJ | 학술논문

探讨在低盐度胁迫下鲻（Mugil cephalus）幼鱼鳃丝 Na+-K+-ATP 酶活性、Na+-K+-ATP 酶β亚基 mRNA表达量变化以及对鳃丝组织显微结构的影响。结果表明：在盐度分别为20（对照组），15，10，5和0实验条件下，20 d 后各低盐度组鳃丝 Na+-K+-ATP 酶活性均高于对照组；0和5盐度组鳃丝 Na+-K+-ATP 酶活性在实验过程中表现为持续上升的趋势，前期升高幅度大，后期升高幅度减小；10和15盐度组鳃丝 Na+-K+-ATP 酶活性在15 d后达到峰值，至20 d 呈现小幅下降趋势。鳃丝 Na+-K+-ATP 酶β亚基 mRNA 表达的变化趋势与 Na+-K+-ATP酶活性的变化趋势基本保持同步，显示出了其对 Na+-K+-ATP 酶活性的调控作用。对鳃丝显微结构观察的结果显示，随着盐度的降低，鲻幼鱼鳃小片逐渐变宽，伴随间距缩小，同时泌氯细胞数量逐渐减少，体积缩小，扁平细胞体积增大，黏液细胞数量增多。这表明在低盐度胁迫下鲻幼鱼鳃的生理功能和组织结构具有随外界水体盐度变化的适应能力。
탐토재저염도협박하치（Mugil cephalus）유어새사 Na+-K+-ATP 매활성、Na+-K+-ATP 매β아기 mRNA표체량변화이급대새사조직현미결구적영향。결과표명：재염도분별위20（대조조），15，10，5화0실험조건하，20 d 후각저염도조새사 Na+-K+-ATP 매활성균고우대조조；0화5염도조새사 Na+-K+-ATP 매활성재실험과정중표현위지속상승적추세，전기승고폭도대，후기승고폭도감소；10화15염도조새사 Na+-K+-ATP 매활성재15 d후체도봉치，지20 d 정현소폭하강추세。새사 Na+-K+-ATP 매β아기 mRNA 표체적변화추세여 Na+-K+-ATP매활성적변화추세기본보지동보，현시출료기대 Na+-K+-ATP 매활성적조공작용。대새사현미결구관찰적결과현시，수착염도적강저，치유어새소편축점변관，반수간거축소，동시비록세포수량축점감소，체적축소，편평세포체적증대，점액세포수량증다。저표명재저염도협박하치유어새적생리공능화조직결구구유수외계수체염도변화적괄응능력。
Summary In natural aquatic system,salinity can largely influence growth,breeding,and even fishes survival. In general, euryhaline fishes often possess strong osmotic adjustment capacity. The gill filaments play an important role in the maintenance of blood ion and acid-base balance in seawater-acclimated fishes,especially if there is a sudden change in water salinity.Seawater-acclimated fishes drink seawater to counter osmotic loss of water,and secrete excess Na+ and Cl- across the gill filaments.When there is a change between freshwater and seawater,euryhaline fishes must transform their gill filaments from an ion-absorbing epithelium to an ion-secreting epithelium,or vice versa.Associated with this transformation is change of Na+/K+-ATPase activity,Na+/K+-ATPase gene expression and structural change of the gill.Euryhaline teleost fishes,such as killifish Fundulus heteroclitus and Mozambique tilapia Oreochromis mossambicus ,have been used as model animals for the study of osmo-and ion-regulation in teleost fish.However,there are little accumulating researches and available literature on juvenile Mugil cephalus .Thus,the objective of the present study is to explore the response and adjustment mechanisms of juvenile M.cephalus to salinity stress. <br> The present study examined the effects of low salinity stress (salinity 1 5,10,5,0,and salinity 20 as control) on Na+-K+-ATPase activities,expression of Na+-K+-ATPase β-subunit mRNA and structural changes in the gill filaments of juvenile M.cephalus during the experimental period of 20 days. <br> The results showed that no fish mortality occurred for all experimental groups during the study period.The Na+-K+-ATPase activities in the gill filament tissue were significantly lower in the control group than in the treatment groups.At the low salinity groups (0 and 5),the Na+-K+-ATPase activities showed rising trends by high and low amplitude during the early and later experimental period,respectively,and the activities at salinity 10 and 1 5 groups attained the maximum value in 1 5 days,and then slightly decreased.The expression of Na+-K+-ATPaseβ-subunit mRNA changed according with the Na+-K+-ATPase activity.It showed rising trend with the decrease of salinity. There were significant differences in Na+-K+-ATPases and their β-subunit mRNA expressions between the control group and salinity 0 group from day 5 to day 20,as well as between the control group and salinity 5 group from day 10 to day 20 (P < 0.05).The highest expression of Na+-K+-ATPase β-subunit mRNA at the salinity 0,5 groups was 4.10 and 2.5 1 times higher than that at the control group respectively,suggesting that the Na+-K+-ATPase β-subunit mRNA played an important role in the process of regulation.With the decrease of salinity,the gill lamellae gradually became wide,and the distance between them as well as the number and size of chloride cells showed decreasing trend,while the size of pavement cells and the number of mucous cells consistently increased. <br> In conclusion,the structure and physiological functions of the gill of juvenile M.cephalus adapt themselves to the salinity change.