Chu Fu-Lin E, Soudant P, Lund E D
Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia 23062, USA.
Exp Parasitol. 2003 Oct;105(2):121-30. doi: 10.1016/j.exppara.2003.11.002.
The effects of temperature on the uptake and metabolism of fluorescent labeled palmitic acid (FLC16) and phosphatidylcholine (FLPC) and lipase activities in the oyster protozoan parasite, Perkinsus marinus, meront stage were tested at 10, 18, and 28 degrees C. Temperature significantly affected not only the uptake, assimilation, and metabolism of both FLC16 and FLPC in P. marinus, but also its triacylglycerol (TAG) lipase activities. The incorporation of both FLC16 and FLPC increased with temperature and paralleled the increase in the amount of total fatty acids in P. marinus meront cultures. The incorporation of FLC16 was higher than FLPC at all temperatures. The percentage of FLC16 metabolized to TAG was significantly higher at higher temperatures. Trace amounts of incorporated FLC16 were detected in monoacylglycerol (MAG) and PC at 18 and 28 degrees C. P. marinus meronts metabolized FLPC to TAG, diacylglycerol (DAG), monoacylglycerol (MAG), free fatty acids (FFA), phosphatidylethanolamine (PE), and cardiolipin (CL). The conversion of FLPC to TAG and PE was highest at 28 degrees C. The relative proportions of individual fatty acids and total saturated, monounsaturated and polyunsaturated fatty acids changed with temperatures. While total saturated fatty acids (SAFAs) increased with temperature, total monounsaturated fatty acids (MUFAs) decreased with temperature. Total polyunsaturated fatty acids (PUFAs) increased from 28 to 18 degrees C. The findings of increase of total SAFAs and decrease of total MUFAs with the increase of temperatures and upward shift of total PUFAs from 28 to 18 degrees C suggest that, as in other organisms, P. marinus is capable of adapting to changes in environmental temperatures by modifying its lipid metabolism. Generally, higher lipase activities were noted at higher cultivation temperatures. Both TAG lipase and phospholipase activities were detected in P. marinus cells and their extra cellular products (ECP), but phospholipase activities in both the cell pellets and ECP were very low. Also, lipase activities were much lower in ECP than in the cells. The observations of low metabolism, bioconversion of incorporated fluorescent lipid analogs and lipase activities at low temperatures are consistent with the low in vitro growth rate and low infectivity of P. marinus at low temperatures.
在10℃、18℃和28℃下测试了温度对牡蛎原生动物寄生虫——海洋派琴虫裂殖体阶段中荧光标记的棕榈酸（FLC16）和磷脂酰胆碱（FLPC）的摄取与代谢以及脂肪酶活性的影响。温度不仅显著影响海洋派琴虫中FLC16和FLPC的摄取、同化及代谢，还显著影响其三酰甘油（TAG）脂肪酶活性。FLC16和FLPC的掺入均随温度升高而增加，且与海洋派琴虫裂殖体培养物中总脂肪酸量的增加平行。在所有温度下，FLC16的掺入均高于FLPC。在较高温度下，FLC16代谢为TAG的百分比显著更高。在18℃和28℃时，在单酰甘油（MAG）和磷脂酰胆碱（PC）中检测到微量掺入的FLC16。海洋派琴虫裂殖体将FLPC代谢为TAG、二酰甘油（DAG）、单酰甘油（MAG）、游离脂肪酸（FFA）、磷脂酰乙醇胺（PE）和心磷脂（CL）。FLPC向TAG和PE的转化在28℃时最高。各个脂肪酸以及总饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸的相对比例随温度变化。总饱和脂肪酸（SFA）随温度升高而增加，总单不饱和脂肪酸（MUFA）随温度降低，总多不饱和脂肪酸（PUFA）在28℃至18℃之间增加。总SFA随温度升高而增加、总MUFA随温度降低以及总PUFA从28℃至18℃向上移动的研究结果表明，与其他生物一样，海洋派琴虫能够通过改变其脂质代谢来适应环境温度变化。一般来说，在较高培养温度下观察到较高的脂肪酶活性。在海洋派琴虫细胞及其细胞外产物（ECP）中均检测到TAG脂肪酶和磷脂酶活性，但细胞沉淀和ECP中的磷脂酶活性都非常低。此外，ECP中的脂肪酶活性远低于细胞中的脂肪酶活性。在低温下观察到的低代谢、掺入的荧光脂质类似物的生物转化以及脂肪酶活性与海洋派琴虫在低温下的低体外生长速率和低感染性一致。
