Nikapitiya Chamilani, Kim Won-Seok, Park Kiyun, Kim Jongkyu, Lee Moon-Ock, Kwak Ihn-Sil
Department of Aqualife Medicine, Chonnam National University, Chonnam, 550-749, Korea.
Cell Stress Chaperones. 2015 May;20(3):517-26. doi: 10.1007/s12192-015-0576-1. Epub 2015 Feb 20.
Changes in salinity affect the physiological status of the marine habitat including that of the intertidal mud crab Macrophthalmus japonicus. Chitinases play significant biological roles in crustaceans such as morphogenesis, nutrient digestion, and pathogen defense. In this study, the osmoregulatory function of three chitinase gene transcripts was determined compared to seawater (SW, 31 ± 1 psu) in M. japonicus gills and hepatopancreas under different salinities (10, 25, and 40 psu) for 1, 4, and 7 days. In SW-exposed crab, quantitative real-time PCR analysis showed chitinase 1 (Mj-chi1) and chitinase 4 (Mj-chi4) transcripts constitutively expressed in all the tested tissues with strong expression in hepatopancreas, but chitinase 5 (Mj-chi5) showed highest expression in stomach. When exposed to different salinities, Mj-chi1 showed significant up-regulation at day 4 whereas Mj-chi4 showed late up-regulation (day 7) at all the salinities in hepatopancreas. In the gills, early up-regulation (day 1) in Mj-chi1 and time-dependent late up-regulation (day 7) in Mj-chi4 at high salinity were observed. These results indicate the possibility of using Mj-chi4 as a marker against salinity changes. Moreover, our results further suggest that Mj-chi1 and Mj-chi4 transcriptions were significantly affected by changes in salinity; however, Mj-chi5 in gills was less affected by salinity and showed no effect in hepatopancreas. Thus, chitinase transcription modulations in the gills are more sensitive than hepatopancreas to salinity stress. Further, present data indicate the possible existence of different physiological roles among chitinase gene families, which need to be clarified in more detail by future biochemical and physiological functional studies.
盐度变化会影响海洋栖息地的生理状态，包括潮间带泥蟹日本大眼蟹的生理状态。几丁质酶在甲壳类动物中发挥着重要的生物学作用，如形态发生、营养消化和病原体防御。在本研究中，比较了日本大眼蟹鳃和肝胰腺中三种几丁质酶基因转录本在不同盐度（10、25和40 psu）下1、4和7天相对于海水（SW，31±1 psu）的渗透调节功能。在暴露于海水的螃蟹中，定量实时PCR分析显示几丁质酶1（Mj-chi1）和几丁质酶4（Mj-chi4）转录本在所有测试组织中组成性表达，在肝胰腺中表达强烈，但几丁质酶5（Mj-chi5）在胃中表达最高。当暴露于不同盐度时，Mj-chi1在第4天显示出显著上调，而Mj-chi4在肝胰腺的所有盐度下均在第7天出现后期上调。在鳃中，在高盐度下观察到Mj-chi1在第1天早期上调，Mj-chi4在第7天出现时间依赖性后期上调。这些结果表明Mj-chi4有可能作为盐度变化的标志物。此外，我们的结果进一步表明，Mj-chi1和Mj-chi4的转录受到盐度变化的显著影响；然而，鳃中的Mj-chi5受盐度影响较小，在肝胰腺中无影响。因此，鳃中几丁质酶转录调节对盐度胁迫比肝胰腺更敏感。此外，目前的数据表明几丁质酶基因家族之间可能存在不同的生理作用，这需要未来通过更多的生化和生理功能研究进行更详细的阐明。
