Sox genes in the coral Acropora millepora: divergent expression patterns reflect differences in developmental mechanisms within the Anthozoa
1 ARC Centre of Excellence for Coral Reef Studies and Comparative Genomics Centre, James Cook University, Townsville, Queensland 4811, Australia
2 ARC Centre for the Molecular Genetics of Development, Research School of Biological Sciences, Australian National University, PO Box 475, Canberra, ACT 2601, Australia
3 Faculty of Life Sciences, University of Vienna, Althanstrasse 14, 1090 Wien, Austria
4 Okinawa Institute of Science and Technology, Urama, Okinawa 904-2234, Japan
5 Graduate School of Engineering and Science, University of the Ryukyus, Nishihara, Okinawa 903-0213, Japan
BMC Evolutionary Biology 2008, 8:311 doi:10.1186/1471-2148-8-311Published: 12 November 2008
Sox genes encode transcription factors that function in a wide range of developmental processes across the animal kingdom. To better understand both the evolution of the Sox family and the roles of these genes in cnidarians, we are studying the Sox gene complement of the coral, Acropora millepora (Class Anthozoa).
Based on overall domain structures and HMG box sequences, the Acropora Sox genes considered here clearly fall into four of the five major Sox classes. AmSoxC is expressed in the ectoderm during development, in cells whose morphology is consistent with their assignment as sensory neurons. The expression pattern of the Nematostella ortholog of this gene is broadly similar to that of AmSoxC, but there are subtle differences – for example, expression begins significantly earlier in Acropora than in Nematostella. During gastrulation, AmSoxBb and AmSoxB1 transcripts are detected only in the presumptive ectoderm while AmSoxE1 transcription is restricted to the presumptive endoderm, suggesting that these Sox genes might play roles in germ layer specification. A third type B Sox gene, AmSoxBa, and a Sox F gene AmSoxF also have complex and specific expression patterns during early development. Each of these genes has a clear Nematostella ortholog, but in several cases the expression pattern observed in Acropora differs significantly from that reported in Nematostella.
These differences in expression patterns between Acropora and Nematostella largely reflect fundamental differences in developmental processes, underscoring the diversity of mechanisms within the anthozoan Sub-Class Hexacorallia (Zoantharia).