Yancey Paul H, Heppenstall Marina, Ly Steven, Andrell Raymond M, Gates Ruth D, Carter Virginia L, Hagedorn Mary
Biology Department, Whitman College, Walla Walla, Washington 99362, USA.
Physiol Biochem Zool. 2010 Jan-Feb;83(1):167-73. doi: 10.1086/644625.
Most marine invertebrates and algae are osmoconformers whose cells accumulate organic osmolytes that provide half or more of cellular osmotic pressure. These solutes are primarily free amino acids and glycine betaine in most invertebrates and small carbohydrates and dimethylsulfoniopropionate (DMSP) in many algae. Corals with endosymbiotic dinoflagellates (Symbiodinium spp.) have been reported to obtain from the symbionts potential organic osmolytes such as glycerol, amino acids, and DMSP. However, corals and their endosymbionts have not been fully analyzed for osmolytes. We quantified small carbohydrates, free amino acids, methylamines, and DMSP in tissues of the corals Fungia scutaria, Pocillopora damicornis, Pocillopora meandrina, Montipora capitata, Porites compressa, and Porites lobata (all with symbionts) plus Tubastrea aurea (asymbiotic) from Kaneohe Bay, Oahu (Hawaii). Glycine betaine, at 33-69 mmol/kg wet mass, was found to constitute 90% or more of the measured organic solutes in all except the Porites species. Those were dominated by proline betaine and dimethyltaurine. DMSP was found at 0.5-3 mmol/kg in all species with endosymbionts. Freshly isolated Symbiodinium from Fungia, P. damicornis, and P. compressa were also analyzed. DMSP and glycine betaine dominated in the first two; Porites endosymbionts had DMSP, proline betaine, and dimethyltaurine. In all specimens, glycerol and glucose were detected by high-performance liquid chromatography only at 0-1 mmol/kg wet mass. An enzymatic assay for glycerol plus glycerol 3-phosphate and dihydroxyacetone phosphate yielded 1-10 mmol/kg. Cassiopeia andromeda (upside-down jelly; Scyphozoan) and Aiptasia puchella (solitary anemone; Anthozoan) were also analyzed; both have endosymbiotic dinoflagellates. In both, glycine betaine, taurine, and DMSP were the dominant osmolytes. In summary, methylated osmolytes dominate in many Cnidaria; in those with algal symbionts, host and symbiont have similar methylated amino acids, as do congeners. However, little glycerol was present as an osmolyte and was probably metabolized before it could accumulate.
大多数海洋无脊椎动物和藻类是渗透顺应者，其细胞积累有机渗透物，这些渗透物提供了一半或更多的细胞渗透压。在大多数无脊椎动物中，这些溶质主要是游离氨基酸和甘氨酸甜菜碱，而在许多藻类中则是小碳水化合物和二甲基磺基丙酸（DMSP）。据报道，具有内共生甲藻（虫黄藻属）的珊瑚从共生体中获取潜在的有机渗透物，如甘油、氨基酸和DMSP。然而，珊瑚及其内共生体的渗透物尚未得到充分分析。我们对来自瓦胡岛（夏威夷）卡内奥赫湾的盾形角孔珊瑚、鹿角杯形珊瑚、梅氏杯形珊瑚、头状蔷薇珊瑚、扁缩孔珊瑚和叶状孔珊瑚组织（均有共生体）以及金色杯珊瑚（无共生体）中的小碳水化合物、游离氨基酸、甲胺和DMSP进行了定量分析。发现甘氨酸甜菜碱的含量为33 - 69 mmol/kg湿质量，在除孔珊瑚属以外的所有珊瑚中，它占所测有机溶质总量的90%或更多。孔珊瑚属珊瑚中的主要渗透物是脯氨酸甜菜碱和二甲基牛磺酸。在所有具有内共生体的物种中都检测到DMSP的含量为0.5 - 3 mmol/kg。还对从盾形角孔珊瑚、鹿角杯形珊瑚和扁缩孔珊瑚中新鲜分离出的虫黄藻进行了分析。在前两种珊瑚的虫黄藻中，DMSP和甘氨酸甜菜碱占主导；孔珊瑚属珊瑚的内共生体含有DMSP、脯氨酸甜菜碱和二甲基牛磺酸。在所有样本中，通过高效液相色谱法仅检测到甘油和葡萄糖的含量为0 - 1 mmol/kg湿质量。通过酶法测定甘油、甘油3 - 磷酸和磷酸二羟丙酮的总量为1 - 10 mmol/kg。还对颠倒水母（钵水母纲）和普氏海葵（海葵目；珊瑚虫纲）进行了分析；它们都有内共生甲藻。在这两种生物中，甘氨酸甜菜碱、牛磺酸和DMSP是主要的渗透物。总之，甲基化渗透物在许多刺胞动物中占主导；在那些具有藻类共生体的刺胞动物中，宿主和共生体具有相似的甲基化氨基酸，同属生物也是如此。然而，作为渗透物的甘油含量很少，可能在其积累之前就被代谢了。
