Morphological responses to feeding in ticks (Ixodes ricinus)
Morphological responses to feeding in ticks (Ixodes ricinus)
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DOI：
10.1186/s40851-018-0104-0
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发表时间：
2018-08-04
影响因子：
2.7
通讯作者：
Hoernig, Marie
中科院分区：
文献类型：
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作者：
Starck, J. Matthias;Mehnert, Lisa;Hoernig, Marie
背景：蜱虫可以在不进食的情况下存活很长时间，但在进食时，会摄入大量血液，导致身体体积增加100倍以上。我们研究了蓖麻蜱（Ixodes ricinus）在摄食过程中对蚓体体积变化的形态学适应。我们的目标是了解适应体积变化的巨大变化的功能形态特征。方法：采用光镜和电镜对成年雌蜱在空腹、半充血和完全充血条件下的表皮表皮、中肠憩室上皮和气管进行了比较。结果：我们的研究结果增加了现有的知识体系，即表皮的面积增加是通过细胞分化、细胞肥大和上皮细胞形状的变化而增加的，在半充血的蜱中，上皮细胞从假分层到单层棱柱状，在完全充血的蜱中，上皮细胞变薄。我们没有发现细胞增殖的证据。中肠憩室通过细胞肥大和细胞形状的改变来适应体积的增加。在完全充血的蜱虫中，中肠憩室的上皮细胞被拉伸成极薄的鳞状上皮。大小和形状的变化（以及细胞分裂）有助于调节体积的变化。气管的大小不会增加，但长度会延长，因此在进食蜱虫时，气管会跟随蚓体的体积变化，以确保内脏器官的氧气供应。结论：表皮和中肠憩室上皮组织形态的改变是蜱对摄食的形态学反应的重要组成部分。我们提供了一种以前未知的机制的证据，这种机制存在于气管内，当身体体积增加，呼吸气门和需要氧气的组织之间的距离增大时，蓖麻豆蜱的气管就会扩张。这是节肢动物首次报道可扩张气管。
Background: Ticks can survive long periods without feeding but, when feeding, ingest large quantities of blood, resulting in a more than 100-fold increase of body volume. We study morphological adaptations to changes in opisthosoma volume during feeding in the castor bean tick, Ixodes ricinus. We aim to understand the functional morphological features that accommodate enormous changes in volume changes.Methods: Using light and electron microscopy, we compare the cuticle and epidermis of the alloscutum, the epithelium of the midgut diverticula, and the tracheae of adult female ticks when fasting, semi-engorged, and fully engorged.Results: Our results add to an existing body of knowledge that the area of the epidermis increases by cellular differentiation, cellular hypertrophy, and changes in the shape of epithelial cells from pseudostratified to single layered prismatic in semi-engorged ticks, and to thin squamous epithelium in fully engorged ticks. We did not find evidence for cell proliferation. The midgut diverticula accommodate the volume increase by cellular hypertrophy and changes in cell shape. In fully engorged ticks, the epithelial cells of the midgut diverticula are stretched to an extremely thin, squamous epithelium. Changes in size and shape (and cell divisions) contribute to the accommodation of volume changes. Tracheae do not increase in size, but extend in length, thus following the volume changes of the opisthosoma in feeding ticks to secure oxygen supply to the internal organs.Conclusions: Changes of epithelial tissue configuration in the epidermis and the midgut diverticula are described as important components of the morphological response to feeding in ticks. We provide evidence for a previously unknown mechanism hosted in the endocuticle of the tracheae that allows the tracheae of castor bean ticks to expand when the body volume increases and the distance between the respiratory spiracle and the oxygen demanding tissue enlarges. This is the first report of expandable tracheae in arthropods.