Biphasic moult cycle of the parasitic isopod Norileca indica (H. Milne Edwards, 1840) (Isopoda: Cymothoidea): stage-wise characterisation and haemolymph ecdysteroids titre
Biphasic moult cycle of the parasitic isopod Norileca indica (H. Milne Edwards, 1840) (Isopoda: Cymothoidea): stage-wise characterisation and haemolymph ecdysteroids titre
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寄生等足类动物 Norileca indica (H. Milne Edwards, 1840)（等足类：Cymothoidea）的双相蜕皮周期：分阶段特征和血淋巴蜕皮类固醇滴度
DOI：
10.1093/jcbiol/ruz082
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发表时间：
2019
影响因子：
1.1
通讯作者：
S. Kappalli
中科院分区：
文献类型：
--
作者：
Amrutha Vani Sahadevan;T. A. J. Priya;S. Kappalli
Norileca indica（H. Milne Edwards，1840）是一种雄性先熟、雌雄同体、专性寄生的等足类。在成年阶段（男性，过渡期，和女性）的这种后部和前部的双相蜕皮周期的特点是基于反映在尾足exopodite和上颌骨，分别微观变化。记录了双相分娩换羽以及产卵雌性特有的去除旧育袋的换羽。血淋巴蜕皮激素滴度测定相对于不同的双相蜕皮周期阶段似乎是第一次报告的水生和/或寄生等足类动物。蜕皮激素的含量随蜕皮周期的不同而有明显的波动，当寄生虫处于双相蜕皮间期时，其含量为13.64 ± 2.09 ng·ml~（-1）。在后体部蜕皮前期，血吸虫滴度逐渐升高，在后体部蜕皮后期和前体部蜕皮中期血吸虫滴度最高（328.54 ± 70.17 ng ml-1; P = 0.0060）。在后半部分蜕皮后不久，到前半部分的蜕皮前变化进入蜕皮后期和即将蜕皮时，其含量急剧下降（92.8 ± 12.95 ng ml-1; P = 0.002）。当寄生虫完成前蜕皮至蜕皮后期时，蜕皮激素滴度为55.56 ± 14.47ng/ml。双相换羽周期的每月发生的数据显示，平均平均23.26%的成年人口经历换羽前/蜕皮/换羽后活动，全年。换羽率（16.12 ± 0.60%）在季风月份（6 - 8月）比前夏季（2 - 5月）（24.83 ± 2.42%）和后季风/冬季（9 - 1月）（26.28 ± 1.75; P = 0.005）下降。
Norileca indica (H. Milne Edwards, 1840) is a protandrous hermaphroditic and obligatory parasitic isopod of scombrid fishes. The posterior and anterior biphasic moult cycles in the adult phases (male, transitional, and female) of this species are characterised based on the microscopic changes reflected in the uropod exopodite and maxillule, respectively. Biphasic parturial moult as well as the moult removing the old brood pouch characteristic of ovigerous females was recorded. Assay of haemolymph ecdysteroids titre with respect to different biphasic moult cycle stages appears to be first report of its kind among aquatic and/or parasitic isopods. The ecdysteroids titre showed significant fluctuation in relation to the moult cycle stages, while the parasite was at a biphasically intermoult stage, titre was estimated to be 13.64 ± 2.09 ng ml–1. By the onset of the premoult at the posterior body region, titre showed a gradual increase and reached a maximum level (328.54 ± 70.17 ng ml–1; P = 0.0060) when the parasite was at late premoult at the posterior body part and mid premoult stage at the anterior body part. There was a subsequent sharp decline (92.8 ± 12.95 ng ml–1; P = 0.002) soon after the ecdysis of the posterior part by the time premoult changes in the anterior part advanced as late premoult and about to moult. The level of ecdysteroids titre was 55.56 ± 14.47 ng ml–1 when the parasite completed anterior ecdysis and reached postmoult. Data on the monthly occurrence of biphasic moult cycles revealed that a mean average of 23.26% of the adult population undergoes premoult/ecdysis/postmoult activities throughout the year. The rate of moulting showed a decline (16.12 ± 0.60%) during the monsoon months (June-August) when compared to pre-summer/summer (February-May) (24.83 ± 2.42%) and post-monsoon/winter (September-January) (26.28 ± 1.75; P = 0.005).