Clustered Brachiopod Hox Genes Are Not Expressed Collinearly and Are
Clustered brachiopod Hox genes are not expressed PNAS PLUS collinearly and are associated with lophotrochozoan novelties Sabrina M. Schiemanna,1, José M. Martín-Durána,1, Aina Børvea, Bruno C. Vellutinia, Yale J. Passamaneckb, and Andreas Hejnol1,a,2 aSars International Centre for Marine Molecular Biology, University of Bergen, Bergen 5006, Norway and bKewalo Marine Laboratory, Pacific Biosciences Research Center, University of Hawaii, Honolulu, HI 96822 Edited by Sean B. Carroll, Howard Hughes Medical Institute and University of Wisconsin–Madison, Madison, WI, and approved January 19, 2017 (received for review August 30, 2016) Temporal collinearity is often considered the main force preserving viding spatial information (29). They also are involved in Hox gene clusters in animal genomes. Studies that combine patterning different tissues (30), and often have been recruited genomic and gene expression data are scarce, however, particularly for the evolution and development of novel morphological traits, in invertebrates like the Lophotrochozoa. As a result, the temporal such as vertebrate limbs (31, 32), cephalopod funnels and arms collinearity hypothesis is currently built on poorly supported foun- (28), and beetle horns (33). dations. Here we characterize the complement, cluster, and expres- Thus, it is not surprising that Hox genes show diverse ar- sion of Hox genes in two brachiopod species, Terebratalia transversa rangements regarding their genomic organization and expression and Novocrania anomala. T. transversa has a split cluster with 10 profiles in the Spiralia (34), a major animal clade that includes lab pb Hox3 Dfd Scr Lox5 Antp Lox4 Post2 Post1 genes ( , , , , , , , , ,and ), highly disparate developmental strategies and body organizations N. anomala Post1 whereas has 9 genes (apparently missing ).
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