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Mercury delays cerebellar development in a model songbird species, the zebra finch
Ecotoxicology ( IF 2.7 ) Pub Date : 2020-08-22 , DOI: 10.1007/s10646-020-02270-9
Sheila A. Scoville , Claire W. Varian-Ramos , G. Alden Adkins , John P. Swaddle , Margaret S. Saha , Daniel A. Cristol

Mercury exposure can disrupt development of the cerebellum, part of the brain essential for coordination of movement through a complex environment, including flight. In precocial birds, such as fowl, the cerebellum develops embryonically, and the chick is capable of leaving the nest within hours of hatching. However, most birds, including all songbirds, are altricial, and spend weeks in the nest between hatching and fledging. The objective of this study was to describe the normal development of the cerebellum in a model altricial songbird so as to determine the effect of exposure to mercury on cerebellar maturation. Adult zebra finch (Taeniopygia guttata) pairs were fed either a control diet, or a diet augmented with one of four treatment-levels of methylmercury (0.3–2.4 μg/g wet weight), and their offspring, the subjects of this study, were fed the same diet by parents. We documented, for the first time, the schedule of cerebellar development in an altricial bird, and compared stages of development among methylmercury-exposed groups. For all treatments of methylmercury, the age of completion of cellular migration was later than for control zebra finches, indicating a delay in cerebellar maturation. Displaced (heterotopic) Purkinje neurons, a pathology typical of methylmercury exposure in developing vertebrate brains, were more numerous in methylmercury-exposed birds, and persisted at least until the age of independence. Delays in maturation of the cerebellum could delay fledging in altricial bird species, with potential serious implications for the fitness of exposed individuals, as predation rates in the nest are often very high.



中文翻译:

水星延缓模型鸣鸟物种斑马雀科的小脑发育

接触汞会破坏小脑的发育,这是大脑在复杂环境(包括飞行)中协调运动必不可少的部分。在诸如鸟类之类的早幼鸟类中,小脑在胚胎中发育,而雏鸡能够在孵化几小时内离开巢穴。但是,大多数鸟类,包括所有鸣禽,都是空巢的,在孵化和出雏之间的巢中待了数周。这项研究的目的是描述模型的鸣禽中小脑的正常发育,从而确定暴露于汞对小脑成熟的影响。成年斑马雀(Taeniopygia guttata)对接受对照饮食或添加了四个治疗水平的甲基汞(0.3–2.4μg/ g湿重)之一的饮食,父母的后代(本研究对象)也接受相同饮食。我们首次记录了一只小鸟中小脑发育的时间表,并比较了甲基汞暴露组之间的发育阶段。对于所有甲基汞治疗,细胞迁移的完成年龄都比对照斑马雀要晚,这表明小脑成熟有所延迟。发育中的脊椎动物脑中甲基汞暴露的典型病理学是位移(异位)浦肯野神经元,在甲基汞接触的禽类中,这种现象更为普遍,并且至少持续到独立年龄。

更新日期:2020-09-28
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