Two lineages of bivalve transmissible neoplasia (BTN), BTN1 and BTN2, are known in blue mussels Mytilus. Both lineages derive from the Pacific mussel M. trossulus and are identified primarily by the unique genotypes of the nuclear gene EF1α. BTN1 is found in populations of M. trossulus from the Northeast Pacific, while BTN2 has been detected in populations of other Mytilus species worldwide but not in M. trossulus itself. The aim of our study was to examine mussels M. trossulus from the Sea of Japan (Northwest Pacific) for the presence of BTN. Using hemocytology and flow cytometry of the hemolymph, we confirmed disseminated neoplasia in our specimens. Cancerous mussels possessed the unique BTN2 EF1α genotype and two mitochondrial haplotypes with different recombinant control regions, similar to that of common BTN2 lineages. This is the first report of BTN2 in its original host species M. trossulus populations in West Pacific may be the birthplace of BTN2 and a natural reservoir where it is maintained and whence it spreads worldwide. A comparison of all available BTN and M. trossulus COI sequences suggests a common and recent, though presumably prehistoric origin of BTN2 diversity in populations of M. trossulus outside the Northeast Pacific.

中文翻译：

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传播性癌症的根源：首次描述了麦芽孢杆菌在米氏麦芽孢杆菌中广泛传播的癌症谱系

蓝贻贝Mytilus中有两个双壳类可传播的肿瘤（BTN）和BTN2。两种谱系均来自太平洋贻贝M. trossulus，主要由核基因EF1α的独特基因型鉴定。在东北太平洋的M. trossulus种群中发现了BTN1，而在全世界的其他Mytilus物种的种群中均检测到了BTN2，但在M. trossulus本身中未发现BTN1。我们研究的目的是检查来自日本海（西北太平洋）的贻贝贻贝是否存在BTN。使用血细胞学和血淋巴的流式细胞仪，我们证实了我们的标本中弥漫性的肿瘤。贻贝癌具有独特的BTN2EF1α基因型和两个具有不同重组控制区的线粒体单倍型，与常见的BTN2谱系相似。这是BTN2在其原始寄主物种中的第一个报道，西太平洋的trossulus种群可能是BTN2的发源地，也是其保存并在那里传播的天然水库。所有可用的BTN和trossulus COI序列的比较表明，在东北太平洋以外的trossulus种群中，BTN2多样性是一个共同的和最近的，尽管大概是史前起源。