Antenna and all gnathal appendages are similarly transformed by homothorax knock-down in the cricket Gryllus bimaculatus

摘要

OurunderstandingofthedevelopmentalmechanismsunderlyingthevastdiversityofarthropodappendageslargelyrestsonthepeculiarcaseofthedipteranemDrosophilamelanogaster/em.Inthisinsect,emhomothorax(hth)/emandemextradenticle(exd)/emtogetherplayapivotalroleinappendagepatterningandidentity.Weinvestigatedtheroleoftheemhth/emhomologueinthecricketemGryllusbimaculatus/embyparentalRNAinterference.ThisspecieshasamoregeneralizedmorphologythanemOncopeltusfasciatus/em,theoneotherinsectbesidesemDrosophila/emwhereemhomothorax/emfunctionhasbeeninvestigated.TheemGryllus/emheadappendagesrepresentthemorphologicallyprimitivestateincludinginsect-typicalmandibles,maxillaeandlabium,structureshighlymodifiedormissinginemOncopeltus/emandemDrosophila/em.WedepletedemGbrsquo;hth/emfunctionthroughparentalRNAitoinvestigateitsrequirementforproperregulationofotherappendagegenes(emGbrsquo;wingless/em,emGbrsquo;dachshund/em,emGbrsquo;aristaless/emandemGbrsquo;Distalless/em)andanalyzedtheterminalphenotypeofemGryllus/emnymphs.emGbrsquo;hth/emRNAinymphsdisplayhomeoticandsegmentationdefectssimilartoemhth/emmutantsorloss-of-functionclonesinemDrosophila/em.Intriguingly,however,wefindthatinemGbrsquo;hth/emRNAinymphsnotonlytheantennaebutalsoallgnathalappendagesarehomeoticallytransformed,suchthatallheadappendagesdifferentiatedistallyaslegsandproximallyasantennae.Hence,emGbrsquo;hth/emisnotspecificallyrequiredforantennalfate,butfulfillsasimilarroleinthespecificationofallheadappendages.Thissuggeststhattheroleofemhth/emintheinsectantennaisnotfundamentallydifferentfromitsfunctionascofactorofsegment-specifichomeoticgenesinmoreposteriorsegments./p/div