Zebrafish Hox Paralogue Group 2 Genes Function Redundantly as Selector Genes to Pattern the Second Pharyngeal Arch

Developmental Biology

Victoria E. Prince¹  Michael P. Hunter¹ 

[1] Department of Molecular Genetics and Cell Biology, The Committees on Developmental Biology, Genetics, Neurobiology and Evolutionary Biology, The University of Chicago, 1027 E. 57th Street, Chicago, Illinois, 60637

关键词: zebrafish;    Hox;    hindbrain;    pharyngeal arches;    morpholino;    knock-down;    selector genes;    redundancy;    Meckel's cartilage;   

DOI  :  10.1006/dbio.2002.0701

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Thepharyngealarchesareoneofthedefiningfeaturesofthevertebrates,withthefirstarchformingthemandiblesofthejawandthesecondformingjawsupportstructures.Thecartilaginouselementsofeacharchareformedfromseparatemigratoryneuralcrestcellstreams,whichderivefromthedorsalaspectoftheneuraltube.ThesecondandmoreposteriorcreststreamsarecharacterizedbyspecificHoxgeneexpression.ThezebrafishhasalargeroverallnumberofHoxgenesthanthetetrapodvertebrates,astheresultofaduplicationeventinitslineage.However,inbothzebrafishandmouse,therearejusttwomembersofHoxparaloguegroup2(PG2):Hoxa2andHoxb2.Here,weshowthatmorpholino-mediated“knock-down”ofbothzebrafishHoxPG2genesresultsinmajordefectsinsecondpharyngealarchcartilages,involvingreplacementofventralelementswithamirror-imageduplicationoffirstarchstructures,andaccompanyingchangestopharyngealmusculature.Inthemouse,nullmutantsofHoxa2haverevealedthatthissingleHoxgeneisrequiredfornormalsecondarchpatterning.Bycontrast,loss-of-functionofeitherzebrafishHoxPG2geneindividuallyhasnophenotypicconsequence,showingthatthesetwogenesfunctionredundantlytoconferproperpatterntothesecondpharyngealarch.Wehavealsousedhoxb1amis-expressiontoinducelocalizedectopicexpressionofzebrafishHoxPG2genesinthefirstarch;usingthisstrategy,wefindthatectopicexpressionofeitherHoxPG2genecanconfersecondarchidentityontofirstarchstructures,suggestingthatthezebrafishHoxPG2genesactas“selectorgenes.”

【 授权许可】

Unknown