Chausson Fabienne, Sanglier Sarah, Leize Emmanuelle, Hagège Agnès, Bridges Christopher R, Sarradin Pierre-Marie, Shillito Bruce, Lallier François H, Zal Franck
Equipe Ecophysiologie, UPMC-CNRS 7127-INSUE, Station Biologique, BP 74, 29682 Roscoff cedex, France.
Micron. 2004;35(1-2):31-41. doi: 10.1016/j.micron.2003.10.010.
Segonzacia mesatlantica (Crustacea; Decapoda; Brachyura) is the only endemic crab species known from the Mid-Atlantic Ridge (MAR) hydrothermal vents. Known from all explored sites in the Atlantic, its wide distribution makes this species a model to study physiological adaptation, and specifically respiratory strategies. Native haemocyanin (Hc) comprises four non-covalent associations in equilibrium formed by monomers, hexamers, dodecamers and octadecamers made up of approximately 75 kDa polypeptide chains. Four different amino acid chains are observed with a molecular mass ranging from 75,234 to 75,972 Da. Experiments carried-out under pressure suggested that the percentage of monomer increased in the haemolymph under hypoxic condition. We have also observed a shift of the proportion of the two dodecamer series, suggesting a rapid modification of the Hc phenotype between hypoxic and hyperoxic conditions. Native Hc possesses a high oxygen affinity ( P50 = 2.2 Torr at 15 degrees C and pH 7.5), a large Bohr effect (Deltalog P50 / DeltapH approximately -2.7) and a slightly reverse temperature effect (DeltaH = +17.19 kJ mol(-1). The composition of Segonzacia haemolymph is similar to that of other littoral species except for the large enrichment in free copper and zinc. As for other species from hydrothermal vent sites, Segonzacia haemolymph possesses a higher buffer capacity than littoral species. Moreover, species from the hydrothermal vent decapods from Pacific hydrothermal vent that encounter higher CO2 content in their environment have a higher buffer capacity than Atlantic vent species. The results presented are discussed in relation with the physico-chemical characteristics of the hydrothermal vent environment.
大西洋中脊（MAR）热液喷口已知的唯一特有蟹种是大西洋中脊蟹（甲壳纲；十足目；短尾亚目）。该物种在大西洋所有已勘探的地点均有发现，其广泛的分布使其成为研究生理适应，特别是呼吸策略的模型。天然血蓝蛋白（Hc）由大约75 kDa的多肽链组成的单体、六聚体、十二聚体和十八聚体在平衡状态下形成四个非共价缔合体。观察到四种不同的氨基酸链，分子量范围为75,234至75,972 Da。在压力下进行的实验表明，低氧条件下血淋巴中单体的百分比增加。我们还观察到两个十二聚体系列比例的变化，表明低氧和高氧条件下Hc表型迅速改变。天然Hc具有高氧亲和力（15℃和pH 7.5时P50 = 2.2 Torr）、大的玻尔效应（Δlog P50 /ΔpH约为 -2.7）和轻微的逆温度效应（ΔH = +17.19 kJ mol⁻¹）。大西洋中脊蟹血淋巴的组成与其他沿海物种相似，只是游离铜和锌的含量大幅增加。与其他来自热液喷口的物种一样，大西洋中脊蟹血淋巴的缓冲能力比沿海物种更高。此外，来自太平洋热液喷口的十足目动物，其环境中二氧化碳含量较高，它们的缓冲能力比大西洋喷口物种更高。结合热液喷口环境的物理化学特征对所得结果进行了讨论。
