Inhibitory gradients of head and foot regeneration in Hydra viridis

[摘要] TheexistenceandcharacteristicsofantiparallelinhibitorygradientsofheadandfootmorphogenesiswereexaminedingraftedHydraviridis.Thefrequenciesofregenerationatthebordersbetweengraftedpieceswasemployedasanassayformorphogenesisand,conversely,forinhibition.Fourtypesofexperimentswereperformed:(1)graftborderswereformedeitherwithorwithoutlengtheninganimalsbytheadditionofregions;(2)thesourcesofthehypotheticalinhibitorswereremoved;(3)additionalsourcesweresupplied;(4)additionaltimewasallowedinmakingthreepartcompositeanimalsbetweengraftingthefirsttwopiecestogetherandaddingthethirdpiece.Inhibitorygradientsaffectingtheabilityofgraftborderstoregenerateheads,buddingregions,andfeetappearedwhenanimalswerelengthenedtoatotalofthreegastricregionsorthreepeduncles.Thelengthsoftheanimal'sbodyperformingthefunctionofthe“sinks”inCrick's(1970)formulationofgradientsexceedCrick'sprediction.Thepossibilitythattheanimal'sterminalheadisthesolesourceofheadinhibitionandthattheanimal'sterminalfootisthesolesourceoffootinhibitionappearstobeoverruledbytheevidencefromtheablationandadditionexperiments.Theexperimentsinvolvingdelayingtheadditionofapieceshowedthatthegradientsarestable,andthatthetimefortheinhibitionofregenerationtobecomeirreversibleisonlyafractionofthetimeforregenerationtobecomedetermined.

[学科分类] 生物科学（综合）