Evolution of the insect Sox genes.
BACKGROUND
The Sox gene family of transcriptional regulators have essential roles during development and have been extensively studied in vertebrates. The mouse, human and fugu genomes contain at least 20 Sox genes, which are subdivided into groups based on sequence similarity of the highly conserved HMG domain. In the well-studied insect Drosophila melanogaster, eight Sox genes have been identified and are involved in processes such as neurogenesis, dorsal-ventral patterning and segmentation.


RESULTS
We examined the available genome sequences of Apis mellifera, Nasonia vitripennis, Tribolium castaneum, Anopheles gambiae and identified Sox family members which were classified by phylogenetics using the HMG domains. Using in situ hybridisation we determined the expression patterns of eight honeybee Sox genes in honeybee embryo, adult brain and queen ovary. AmSoxB group genes were expressed in the nervous system, brain and Malphigian tubules. The restricted localization of AmSox21b and AmSoxB1 mRNAs within the oocyte, suggested a role in, or that they are regulated by, dorsal-ventral patterning. AmSoxC, D and F were expressed ubiquitously in late embryos and in the follicle cells of the queen ovary. Expression of AmSoxF and two AmSoxE genes was detected in the drone testis.


CONCLUSIONS
Insect genomes contain between eight and nine Sox genes, with at least four members belonging to Sox group B and other Sox subgroups each being represented by a single Sox gene. Hymenopteran insects have an additional SoxE gene, which may have arisen by gene duplication. Expression analyses of honeybee SoxB genes implies that this group of genes may be able to rapidly evolve new functions and expression domains, while the combined expression pattern of all the SoxB genes is maintained.
Wilson
Megan J
MJ
Laboratory for Evolution and Development, National Research Centre for Growth and Development, Department of Biochemistry, University of Otago, PO Box 56, Dunedin, New Zealand. meganj.wilson@otago.ac.nz
Dearden
Peter K
PK
D000818:Animals; D001499:Bayes Theorem; D018076:DNA, Complementary; D004475:Ectoderm / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000378:metabolism; D019143:Evolution, Molecular; D005260:Female; D020440:Gene Duplication; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D006609:High Mobility Group Proteins / Q000235:genetics* / Q000378:metabolism; D017403:In Situ Hybridization; D007313:Insecta / Q000196:embryology / Q000235:genetics*; D008297:Male; D009865:Oocytes / Q000378:metabolism; D010802:Phylogeny; D015347:RNA Probes; D019849:Sex Determination Processes; D013737:Testis / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D006609:High Mobility Group Proteins; D015347:RNA Probes; D014157:Transcription Factors