Forconi Mariko, Biscotti Maria Assunta, Barucca Marco, Buonocore Francesco, De Moro Gianluca, Fausto Anna Maria, Gerdol Marco, Pallavicini Alberto, Scapigliati Giuseppe, Schartl Manfred, Olmo Ettore, Canapa Adriana
Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, Ancona, Italy.
J Exp Zool B Mol Dev Evol. 2014 Sep;322(6):334-41. doi: 10.1002/jez.b.22515. Epub 2013 Jun 3.
Coelacanths are a critically valuable species to explore the gene changes that took place in the transition from aquatic to terrestrial life. One interesting and biologically relevant feature of the genus Latimeria is ureotelism. However not all urea is excreted from the body; in fact high concentrations are retained in plasma and seem to be involved in osmoregulation. The purine catabolic pathway, which leads to urea production in Latimeria, has progressively lost some steps, reflecting an enzyme loss during diversification of terrestrial species. We report the results of analyses of the liver and testis transcriptomes of the Indonesian coelacanth Latimeria menadoensis and of the genome of Latimeria chalumnae, which has recently been fully sequenced in the framework of the coelacanth genome project. We describe five genes, uricase, 5-hydroxyisourate hydrolase, parahox neighbor B, allantoinase, and allantoicase, each coding for one of the five enzymes involved in urate degradation to urea, and report the identification of a putative second form of 5-hydroxyisourate hydrolase that is characteristic of the genus Latimeria. The present data also highlight the activity of the complete purine pathway in the coelacanth liver and suggest its involvement in the maintenance of high plasma urea concentrations.
腔棘鱼是探索从水生到陆生生命转变过程中基因变化的极具价值的物种。矛尾鱼属一个有趣且与生物学相关的特征是排尿素代谢。然而，并非所有尿素都从体内排出；事实上，高浓度的尿素保留在血浆中，似乎参与了渗透压调节。在矛尾鱼中导致尿素产生的嘌呤分解代谢途径已逐渐失去了一些步骤，这反映了陆生物种多样化过程中的酶丢失。我们报告了对印度尼西亚腔棘鱼曼氏矛尾鱼肝脏和睾丸转录组以及在腔棘鱼基因组计划框架内最近已完成全测序的腔棘鱼基因组分析的结果。我们描述了五个基因，尿酸酶、5-羟基异尿酸水解酶、副同源基因邻域B、尿囊素酶和尿囊酸酶，每个基因编码参与尿酸降解为尿素的五种酶之一，并报告了鉴定出一种推定的5-羟基异尿酸水解酶的第二种形式，这是矛尾鱼属的特征。目前的数据还突出了腔棘鱼肝脏中完整嘌呤途径的活性，并表明其参与维持高血浆尿素浓度。
