贻贝发育早期酯酶和过氧化物酶活性

Esterase and Peroxidase Activities of Mussel Mytilus edulis in Early Development

采用组织化学和分光光度技术对贻贝(Mytilus edulis)发育早期酯酶(Esterase,EST)和过氧化物酶(Per-oxidase,POD)活性进行了研究,以探讨贝类早期发育过程中的免疫防御机制。EST和POD均存在于贻贝的卵母细胞、胚胎和幼虫中,但在各个发育时期的分布和含量不同。组织化学定位结果表明,从卵母细胞到D型面盘幼虫各个发育时期的胚胎和幼虫均呈EST强阳性和POD阳性;卵母细胞核区较大且颜色较浅;桑椹期开始出现不同细胞阳性的强弱差异;原肠胚、担轮幼虫和D型面盘幼虫细胞间阳性强弱的差异逐步增大。分光光度测定结果表明,α-醋酸酯酶活力,卵母细胞最低,受精卵略有提高,卵裂期胚胎提高较大且达最高峰,囊胚、原肠胚和担轮幼虫又逐渐下降,D型面盘幼虫下降较大;α-丁酸酯酶活力,卵母细胞较高,受精卵略有提高且达到最高峰,卵裂期胚胎到D型面盘幼虫各个时期逐渐下降,D型面盘幼虫最低。不依赖卤素POD活力,卵母细胞最低,受精卵提高较大,囊胚达到最高峰,原肠胚、担轮幼虫和D型面盘幼虫逐渐降低。依赖卤素POD活力与不依赖卤素POD活力的变化规律相似,但受精卵提高较小,而卵裂期提高较大。EST和POD可能在贻贝的发育早期抵抗病原微生物侵染方面发挥重要作用。

In this paper, the histochemical and spectrophotometric methods are used to study the esterase （EST） and peroxidase （POD） activities of mussel in early development so as to probe into the immunodefence mechanism in early shellfish development process. It is shown from the analysis results that EST and POD all existed in oocyte, embryo and larva of mussel, but the distributions and contents of EST and POD in different early development stages were different. It is shown from the histochemical localization results that the embryos and larvae in different development stages all showed strong EST positive reaction and POD positive reaction, oocyte had a larger nucleus and lighter color, the difference in positive reaction of EST and POD between different cells occurred from the morula stage, and this difference in the stages of gastrula, trochophore larva and D-veliger larva gradually increased. It is shown from the spectrophotometric results that the activity level of α-acetate esterase in oocyte was the lowest, that in fertilized egg slightly increased, that in cleavage stage embryo greatly increased and reached the highest, that in blastula, gastrula and trochophore larva gradually decreased and that in D-veliger larva greatly decreased; the activity level of α-butyrate esterase in oocyte was higher, that in fertilized egg slightly increased and reached the highest, that in cleavage stage larva to D-veliger larva gradually decreased, and that in D-veliger larva was the lowest. The activity level of halide-independent peroxidase in oocyte was the lowest, that in fertilized egg greatly increased, that in blastula reached the highest, and that in gastrula, trochophore larva and Dveliger larva gradually decreased. The variabilities in activity level of halid-dependent peroxidase are similar to those of halid-independent peroxidase. EST and POD may play an important role in resisting the attack of pathogens in the early mussel development stage.