Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan; Department of Marine Sciences, College of Science and Mathematics, Mindanao State University-Iligan Institute of Technology, Iligan City, Philippines.
Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan.
Gene. 2020 Apr 30;736:144421. doi: 10.1016/j.gene.2020.144421. Epub 2020 Feb 1.
5-Aminolevulinic acid synthase (ALAS) is the rate-limiting enzyme in the biosynthesis of heme, a prosthetic group that is found in hemoproteins, including those involved in molting. To better understand the roles of ALAS in L. vannamei (LvALAS), we analyzed its sequence and tissue distribution, the effects of age and bacterial infection on its gene expression, and the effects of LvALAS gene silencing. We also examined the expressions of three hemoproteins, the cytochrome oxidase subunit I (COX I) and subunit IV (COX IV) and catalase. Three LvALAS splicing variants were found in the hepatopancreas, with the main splicing variant having an open reading frame that encodes 532 aa. LvALAS transcripts were found in each of the eleven tissues tested in this study, with the highest gene expression in the intestine. The transcript abundances of LvALAS, COX I and COX IV in the hepatopancreas and stomach tended to decrease with age. LvALAS and catalase gene expressions significantly increased in the stomach after V. parahaemolyticus infection. LvALAS gene expression in the hepatopancreas, stomach and intestine (12- and 24-hours post-injection) was relatively lower in dsALAS-injected shrimp than in PBS-injected shrimp. All the PBS-injected shrimp molted after 8-10 days while no molting activity was observed in the dsALAS-injected shrimp group within the 14 days post-injection period. Our results provide evidence that (1) only the housekeeping form of ALAS exists in L. vannamei; LvALAS gene expression (2) decreases with age and (3) increases after bacterial infection; and (4) an ALAS-dependent pathway is necessary for proper molting in L. vannamei.
5-氨基酮戊酸合酶（ALAS）是血红素生物合成的限速酶，血红素是一种存在于血红素蛋白中的辅基，包括参与蜕皮的蛋白。为了更好地了解 ALAS 在凡纳滨对虾（LvALAS）中的作用，我们分析了其序列和组织分布、年龄和细菌感染对其基因表达的影响以及 LvALAS 基因沉默的影响。我们还检查了三种血红素蛋白，细胞色素氧化酶亚基 I（COX I）和亚基 IV（COX IV）和过氧化氢酶的表达。在肝胰腺中发现了三种 LvALAS 剪接变体，主要剪接变体具有编码 532 个氨基酸的开放阅读框。在所研究的 11 种组织中的每种组织中都发现了 LvALAS 转录物，在肠中基因表达最高。肝胰腺和胃中的 LvALAS、COX I 和 COX IV 的转录物丰度随年龄的增长而降低。感染副溶血弧菌后，胃中的 LvALAS 和过氧化氢酶基因表达显著增加。肝胰腺、胃和肠（注射后 12 和 24 小时）中 LvALAS 基因表达在 dsALAS 注射虾中相对较低，而在 PBS 注射虾中则较高。所有 PBS 注射虾在 8-10 天后蜕皮，而在注射后 14 天内，dsALAS 注射虾组未观察到蜕皮活动。我们的结果表明：（1）只有组成型形式的 ALAS 存在于凡纳滨对虾中；（2）LvALAS 基因表达随年龄的增长而降低；（3）感染细菌后增加；（4）ALAS 依赖性途径是凡纳滨对虾蜕皮所必需的。
