Hill April, Wagner Aimee, Hill Malcolm
Biology Department, Fairfield University, Fairfield, CT 06430, USA.
Mol Phylogenet Evol. 2003 Sep;28(3):529-35. doi: 10.1016/s1055-7903(03)00062-9.
We surveyed the genome of the Caribbean zoanthid Parazoanthus parasiticus for Hox and paraHox genes, and examined gene expression patterns for sequences we uncovered. Two Hox genes and three paraHox genes were identified in our surveys. The Hox genes belong to anterior and posterior classes. In phylogenetic analyses, the anterior Hox sequence formed an anthozoan-specific cluster that appears to be a second class of cnidarian anterior Hox gene. The presence of an anterior Gsx-like paraHox gene supports the hypothesis that duplication of a protoHox gene family preceded the divergence of the Cnidaria and bilaterians. The presence of two Mox class paraHox genes in P. parasiticus deserves further attention. Expression analysis using RT-PCR, indicated that one Mox gene and the anterior paraHox gene are not expressed in adult tissue, whereas the other three sequences are expressed in both dividing and unitary polyps. Dividing polyps showed slightly lower Ppox1 (i.e., Mox) expression levels. Our data add to the number of published anthozoan sequences, and provide additional detail concerning the evolutionary significance of cnidarian Hox and paraHox genes.
我们对加勒比海的寄生拟花珊瑚（Parazoanthus parasiticus）的基因组进行了霍克斯（Hox）基因和副霍克斯（paraHox）基因的调查，并研究了我们所发现序列的基因表达模式。在我们的调查中鉴定出了两个霍克斯基因和三个副霍克斯基因。这些霍克斯基因属于前部和后部类别。在系统发育分析中，前部霍克斯序列形成了一个珊瑚虫纲特有的簇，似乎是刺胞动物前部霍克斯基因的第二类。前部类Gsx副霍克斯基因证实了这样一个假设，即原霍克斯基因家族的复制先于刺胞动物和两侧对称动物的分化。寄生拟花珊瑚中存在两个Mox类副霍克斯基因值得进一步关注。使用逆转录聚合酶链反应（RT-PCR）进行的表达分析表明，一个Mox基因和前部副霍克斯基因在成体组织中不表达，而其他三个序列在分裂型和单体型息肉中均有表达。分裂型息肉的Ppoxl（即Mox）表达水平略低。我们的数据增加了已发表的珊瑚虫纲序列数量，并提供了有关刺胞动物霍克斯基因和副霍克斯基因进化意义的更多细节。
