Satora Leszek, Kozioł Katarzyna, Zebrowski Jacek
Department of Animal Physiology and Reproduction, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland.
Department of Animal Physiology and Reproduction, University of Rzeszow, Werynia 502, 36-100 Kolbuszowa, Poland.
Acta Histochem. 2017 Jun;119(5):563-568. doi: 10.1016/j.acthis.2017.05.010. Epub 2017 Jun 8.
Accessory respiratory organs in fish exhibit great diversity but share the presence of numerous capillaries covered by a simple squamous epithelium. The adoption of the intestine for respiratory function needs certain special modifications. In this study, we explored immunohistochemical and metabolic fingerprint features that could underlay this adaptation in bronze corydoras Corydoras aeneus. Immunohistochemical localization of the cytoplasmic domain of epidermal growth factor receptor (EGFR) in the respiratory part of intestine demonstrated a strong positive immunoreaction in epithelial cells and connective tissue. Fourier Transfer Infrared (FTIR) spectroscopy coupled with chemometrics discriminated between anterior and posterior region of intestine in terms of secondary structure of proteins and the abundance of p-cresol and other phenolics. The latter were reduced in the posterior part of intestine, indicating the cessation of digestive function in this region. It has been suggested that aquatic hypoxia via endocrine cells (hypoxia-sensitive) activate EGFR, which induce proliferation of squamous epithelial cells, thereby enabling gas diffusion in the posterior part of intestine. It seems that hypoxia and normoxia are opposed conditions adjusting the production of squamous epithelial cells in this intestine. The physiological role of EGFR in the respiratory intestine of bronze corydoras is of interest not only from an evolutionary aspect but also in terms of a potential model for observations process proliferation squamous epithelial cells. Future investigations on the molecular responses to different water oxygen levels in air-breathing bronze corydoras fish are required to clarify the mechanism responsible for squamous cell proliferation.
鱼类的辅助呼吸器官表现出极大的多样性，但都有一个共同点，即存在大量由单层扁平上皮覆盖的毛细血管。肠道承担呼吸功能需要一些特殊的适应性变化。在本研究中，我们探究了青铜兵鲶（Corydoras aeneus）肠道这种适应性变化背后的免疫组化和代谢指纹特征。表皮生长因子受体（EGFR）胞质结构域在肠道呼吸部分的免疫组化定位显示，上皮细胞和结缔组织中有强烈的阳性免疫反应。傅里叶变换红外（FTIR）光谱结合化学计量学，根据蛋白质的二级结构以及对甲酚和其他酚类物质的丰度，区分了肠道的前部和后部区域。后者在肠道后部减少，表明该区域消化功能停止。有人提出，水生低氧通过内分泌细胞（对低氧敏感）激活EGFR，进而诱导扁平上皮细胞增殖，从而使肠道后部能够进行气体扩散。似乎低氧和常氧是调节该肠道中扁平上皮细胞产生的相反条件。EGFR在青铜兵鲶呼吸肠道中的生理作用不仅从进化角度来看很有趣，而且就观察扁平上皮细胞增殖过程的潜在模型而言也很有趣。未来需要对呼吸空气的青铜兵鲶鱼对不同水体氧水平的分子反应进行研究，以阐明负责扁平细胞增殖的机制。
