Nethathe Bono, Abera Aron, Naidoo Vinny
Department of Paraclinical Science, Faculty of Veterinary Science, University of Pretoria, Onderstepoort, Pretoria, South Africa.
Department of Food Science and Technology, University of Venda, Thohoyandou, Limpopo, South Africa.
PeerJ. 2020 Dec 1;8:e10422. doi: 10.7717/peerj.10422. eCollection 2020.
Diclofenac toxicity in old world vultures is well described in the literature by both the severity of the toxicity induced and the speed of death. While the mechanism of toxicity remains unknown at present, the necropsy signs of gout suggests primary renal involvement at the level of the uric acid excretory pathways. From information in the chicken and man, uric acid excretion is known to be a complex process that involves a combination of glomerular filtration and active tubular excretion. For the proximal convoluted tubules excretion occurs as a two-step process with the basolateral cell membrane using the organic anion transporters and the apical membrane using the multidrug resistant protein to transport uric acid from the blood into the tubular fluid. With uric acid excretion seemingly inhibited by diclofenac, it becomes important to characterize these transporter mechanism at the species level. With no information being available on the molecular characterization/expression of MRPs of , for this study we used next generation sequencing, and Sanger sequencing on the renal tissue of African white backed vulture (AWB), as the first step to establish if the MRPs gene are expressed in AWB. In silico analysis was conducted using different software to ascertain the function of the latter genes. The sequencing results revealed that the MRP2 and MRP4 are expressed in AWB vultures. Phylogeny of avian MRPs genes confirms that vultures and eagles are closely related, which could be attributed to having the same ancestral genes and foraging behavior. In silico analysis confirmed the transcribed proteins would transports anionic compounds and glucose.
文献中对旧大陆秃鹫双氯芬酸毒性已有充分描述，包括所诱导毒性的严重程度和死亡速度。虽然目前毒性机制尚不清楚，但痛风的尸检迹象表明尿酸排泄途径层面存在原发性肾脏受累。从鸡和人的相关信息可知，尿酸排泄是一个复杂过程，涉及肾小球滤过和肾小管主动排泄的结合。对于近端曲管，排泄过程分两步进行，基底外侧细胞膜利用有机阴离子转运体，顶端细胞膜利用多药耐药蛋白将尿酸从血液转运至肾小管液。由于双氯芬酸似乎抑制了尿酸排泄，在物种层面表征这些转运机制就变得很重要。由于没有关于非洲白背秃鹫（AWB）多药耐药蛋白（MRPs）分子表征/表达的信息，在本研究中，我们对非洲白背秃鹫的肾脏组织进行了新一代测序和桑格测序，作为确定MRPs基因是否在AWB中表达的第一步。使用不同软件进行了电子分析，以确定后述基因的功能。测序结果显示，MRP2和MRP4在AWB秃鹫中表达。鸟类MRPs基因的系统发育证实秃鹫和鹰关系密切，这可能归因于拥有相同的祖先基因和觅食行为。电子分析证实转录的蛋白质会转运阴离子化合物和葡萄糖。
