4种壳色菲律宾蛤仔在低氧胁迫下的耐受能力比较研究

Comparison of hypoxia stress tolerance among Manila clam Ruditapes philippinarum with four shell-colors

菲律宾蛤仔Ruditapes philippinarum对环境中溶氧剧烈的波动有较强的适应能力,为了探讨抗氧化酶和热休克蛋白在蛤蛤恣仔的低氧耐受过程中发挥的作用,以对低氧具有不同耐受能力的4种壳色蛤仔(野生蛤仔、斑马蛤、白蛤、白斑马蛤)为研究对象,比较了在1 mg/L的低氧胁迫条件下其抗氧化酶家族基因成员(TPx、CAT、Mn-SOD、Cu/Zn-SOD)和热休克蛋白家族基因成员(HSP40、HSP75、Vps HSP-1、Vps HSP-2)的表达量变化情况。结果表明:在鳃组织中,野生蛤仔的抗氧化酶基因表现出先升高后恢复的趋势,在胁迫后6 h时表达量达到最高值(P<0.05),其他3种壳色蛤仔的抗氧化酶基因表现出先降低后恢复的趋势,在胁迫后6 h时表达量达到最低值(P<0.05),斑马蛤的TPx基因表达量在胁迫的各个时间点均显著高于其他3种壳色蛤仔(P<0.05);在外套膜组织中,4种壳色蛤仔中的抗氧化酶基因均表现出先升高后恢复的趋势,白蛤TPx基因和白斑马蛤CAT基因表达量在胁迫的各个时间点均显著高于其他3种壳色蛤仔(P<0.05);在鳃组织中,斑马蛤和白斑马蛤中热休克蛋白家族基因成员表现出先降低后升高再降低的趋势,分别在24 h、6 h时达到最低值(P<0.05),野生蛤仔和白蛤中热休克蛋白家族基因成员表现出先升高后降低的趋势,在胁迫6 h时,白蛤热休克蛋白家族基因成员表达量达到最高值(P<0.05),胁迫12 h时,野生蛤仔达到最高值(P<0.05);在外套膜组织中,白斑马蛤中热休克蛋白家族基因成员表达量出现先降低后升高的趋势,在胁迫6 h时达到最低值(P<0.05),而其他3个壳色蛤仔中热休克蛋白家族基因表达量表现出先升高后降低的趋势,在胁迫6 h时野生蛤仔和白蛤热休克蛋白家族基因成员表达量达到最大值(P<0.05),12 h时斑马蛤达到最大值(P<0.05),且白蛤HSP40基因表达量在胁迫的各个时间点均显著高于其他3种壳色蛤仔(P<0.05)。研究表明,斑马蛤和白蛤的TPx基因可能参与其体内黑色素合成的过程,初步证实了不同壳色蛤仔参与色素合成过程的相关基因在其对低氧的耐受过程中能够发挥重要作用。

In this study,the expression of antioxidant enzymes（ TPx,CAT,Mn-SOD,and Cu/Zn-SOD） and heat shock proteins（ HSP40,HSP75,Vps HSP-1,and Vps HSP-2） family members were compared in Manila clam Ruditapes philippinarum with four shell-colors,as one intertidal shellfish in drastic change in dissolved oxygen level,exposed to 1 mg/L dissolved oxygen level to probe into the important role of antioxidant enzymes and heat shock proteins in the hypoxia stress in Manila clam. The results showed that first increase and then recovery to normal level in expression levels of members in the antioxidant gene family were found in mantle tissue in the four shell-color clam,the peak expression in 6 h hypoxia stress（ P〈0.05）. The expression of TPx gene in mantle tissue was significantly higher in white clam and CAT gene in the white zebra-colored clam than those in the clam with other three shell colors challenged with low dissolved O2（ P〈0.05）. The expression levels of genes in heat shock protein family in the gills were found to be first decrease and then to be increase in the white zebra-colored clam and zebra-colored clam,with the minimum at 6 h after the hypoxic stress（ P〈0.05）. The expression of these genes in wild clam and white clam was increased first and then reduced,with the maximal level in 6 h hypoxia stress in white color group（ P〈0.05）,and in 12 h hypoxia stress in the wild clam（ P〈0.05）. The expression of heat shock proteins in mantle was reduced first and then increased in the white-zebra group,with the minimal level in 6 h hypoxia stress（ P〈0.05）,while in the clam with other three shell colors the expression of heat shock proteins in mantle was increased first and then reduced,with the maximal level in 6 h hypoxia stress in wild clam and white shell-colored clam（ P〈0.05）,and the maximal levels in zebra-colored clam in 12 h hypoxia stress（ P〈0.05）,and significantly higher in white clam than those in the clam with other three shell colors（ P 〈0.05）. The findings indicate that the TPx gene of zebra-colored clam and white clam may be response for process of the melanin synthesis,and that the genes related to melanin synthesis play an important role in hypoxia stress tolerance.