Cellulose digestion by common Japanese freshwater clam Corbicula japonica
Cellulose digestion by common Japanese freshwater clam Corbicula japonica
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日本淡水蛤 Corbicula japonica 的纤维素消化
DOI：
10.1111/j.1444-2906.2007.01381.x
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发表时间：
2007
影响因子：
1.9
通讯作者：
H. Toyohara
中科院分区：
文献类型：
--
作者：
K. Sakamoto;K. Touhata;M. Yamashita;A. Kasai;H. Toyohara
在没有任何共生助剂的情况下，该生物可以利用纤维素作为碳源，研究了该生物对纤维素的消化。酶学研究表明该物种具有完整的纤维素酶活性，分子克隆获得了编码596个氨基酸的开放阅读框架的cDNA，与鲍鱼和白蚁纤维素酶有显著的同源性，氨基酸同源性分别为52.2%和50.5%。分离的纤维素酶在N端有一个碳水化合物结合模块，据报道该模块也存在于鲍鱼纤维素酶中，其mRNA在消化腺中特异表达。这些发现有力地支持了日本对虾以及鲍鱼和白蚁具有内源纤维素的假设。人们进一步认为，日本毛白蚁在分解纤维素的过程中发挥着重要作用，因此有助于水环境中的碳循环，就像白蚁在陆地森林中所做的那样。
Cellulose digestion by Corbicula japonica was investigated according to the hypothesis that without any symbiotic aid, this organism can utilize cellulose as a carbon source. Enzymatic studies revealed the complete cellulase activity of this species, and molecular cloning resulted in the isolation of cDNA with an ORF encoding a 596-amino-acid protein that shares significant homology with abalone and termite cellulases with an amino acid identity of 52.2% and 50.5%, respectively. The isolated cellulase had a carbohydrate-binding module at the N-terminal region that was also reportedly present in abalone cellulase, and its mRNA were specifically expressed in the digestive gland. These findings strongly support the assumption that C. japonica has an endogenous cellulose, as well as abalones and termites. It is further believed that C. japonica plays an important roll in decomposing cellulose, and consequently contributes to the carbon-cycle in the aquatic environment, as termites do in terrestrial forests.