Survival, feeding and embryo development of Gyrodactylus gasterostei (Monogenea: Gyrodactylidae)
Survival, feeding and embryo development of Gyrodactylus gasterostei (Monogenea: Gyrodactylidae)
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DOI：
10.1017/s0031182001008861
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发表时间：
2002-01-01
期刊：
影响因子：
2.4
通讯作者：
Harris, PD
中科院分区：
文献类型：
--
作者：
Cable, J;Tinsley, RC;Harris, PD
与宿主分离的胎生单系旋虫可能是鱼类群落中重要的感染源。这对那些没有特定自由生活阶段的外寄生虫尤其重要，它们的传播通常是通过鱼类密切接触时成年寄生虫的转移发生的。在本研究中，胃骨旋毛虫的体外存活与亲本及其胚胎在分离期间和返回宿主后的组织超微结构变化有关。在10℃条件下，离体线虫存活长达89 h(50%存活率= 20 h)，死亡率受年龄无关和年龄相关因素的影响。寄生物的腹真皮是合胞的，含有各种囊泡和摄食液泡。然而，在脱离和饥饿后，胃真皮层内发生退行性变化，最终导致胚胎明显受损。当饥饿的蠕虫重新附着在鱼身上时，它们在1分钟内开始啃食宿主上皮细胞，5分钟后在胃真皮层检测到吞噬活性的超微结构证据。假设的废液泡在新宿主体内5-30分钟后大量增加，与电子密集囊泡的重现一致，可能表明完成了第一个细胞内消化周期。父母喂养直接影响子宫内膜在分娩之间的正常周期成熟和退化。在极端情况下，饥饿导致分离的寄生虫（6-1%）流产胚胎。然而，即使短时间脱离宿主也会影响胚胎的发育和存活，这表明暂时中断胚胎的营养流动可以显著影响回行虫的繁殖率。
Viviparous gyrodactylid monogeneans which are detached from their host may form an important source of infection in fish communities. This is particularly significant for these ectoparasites which have no specific free-living stage and where transmission usually occurs through transfer of adult parasites when fish come into close contact. In this study, in vitro survival of Gyrodactylus gasterostei was correlated with changes in tissue ultrastructure of parents and their embryos during detachment and following return to a host. At 10 degreesC, detached worms survived for up to 89 h (50% survival = 20 h) with mortality influenced by both age-independent and age-dependent factors. The gastrodermis of attached, fed parasites is syncytial and contains a variety of vesicles and feeding vacuoles. However, following detachment and starvation, degenerative changes occur within the gastrodermis, eventually leading to marked damage to the embryo/s. When starved worms reattached to a fish, they began browsing on host epithelial cells within 1 min and ultrastructural evidence for phagocytic activity in the gastrodermis was detected after 5 min. Putative waste vacuoles increased in abundance after 5-30 min on the new host, coinciding with the reappearance of electron-dense vesicles and possibly indicating completion of the first intracellular cycle of digestion. Parental feeding directly influenced the normal cyclical maturation and regression of the uterine lining between births. In extreme cases, starvation led to detached parasites (6-1%) aborting their embryos. However, even short periods off the host influenced development and survival of embryos, suggesting that temporary interruption of nutrient flow to the embryo can significantly affect gyrodactylid reproductive rates.