Rohloff Peter, Docampo Roberto
Department of Pathobiology and Medical Scholars Program, University of Illinios at Urbana-Champaign, Urbana, IL 61801, USA.
Exp Parasitol. 2008 Jan;118(1):17-24. doi: 10.1016/j.exppara.2007.04.013. Epub 2007 May 10.
Acidocalcisomes are dense, acidic organelles with a high concentration of phosphorus present as pyrophosphate and polyphosphate complexed with calcium and other cations. Acidocalcisomes have been linked to the contractile vacuole complex in Chlamydomonas reinhardtii, Dictyostelium discoideum, and Trypanosoma cruzi. A microtubule- and cyclic AMP-mediated fusion of acidocalcisomes to the contractile vacuole complex in T. cruzi results in translocation of aquaporin and the resulting water movement which, in addition to swelling of acidocalcisomes, is responsible for the volume reversal not accounted for by efflux of osmolytes. Polyphosphate hydrolysis occurs during hyposmotic stress, probably increasing the osmotic pressure of the contractile vacuole and facilitating water movement.
酸性钙小体是致密的酸性细胞器，含有高浓度以焦磷酸和多磷酸形式存在的磷，这些磷与钙及其他阳离子结合。酸性钙小体已被证实与莱茵衣藻、盘基网柄菌和克氏锥虫中的收缩泡复合体相关。在克氏锥虫中，微管和环磷酸腺苷介导酸性钙小体与收缩泡复合体融合，导致水通道蛋白移位以及随之产生的水流动，除了酸性钙小体肿胀外，这也是溶质外流无法解释的体积逆转的原因。低渗胁迫期间会发生多磷酸水解，这可能会增加收缩泡的渗透压并促进水的流动。
