Hyaluronidase activity and glycosaminoglycan synthesis in the amputated newt limb: Comparison of denervated, nonregenerating limbs with regenerates☆

[摘要] Amputated,regeneratingforelimbshavebeencomparedwiththecontralateral,denervatednon-regeneratinglimbstumpsintheadultnewtNotophthalmusviridescens,withrespecttohyaluronidaseactivityandtheincorporationof3H-acetateintoglycosaminoglycans(GAG).At10daysafteramputation,whichisthetimeofmaximumhyaluronateproductionintheearlygrowingregenerate,incorporationof3H-acetateintoGAG(cpm/mgprotein)inthedenervated,nonregeneratinglimbstumpwasapproximately50%ofthatinthecontralateralregeneratinglimbs.Atthisstage,hyaluronatewasthemajorGAGbeingproduced,buttheratioofincorporationintohyaluronaterelativetochondroitinsulfatewasreducedinthedenervatedlimbs.Inintact,nonamputatedlimbs,theincorporationintoGAGwas5%ofthatintheregeneratinglimb10daysafteramputation,and10%ofthatinthedenervatedstumps.At25days,cartilageisformingandchondroitinsulfatesynthesispredominatesinthenormalregeneratewhilstthecontralateral,denervatedlimbstumpsareformingscars.GAGsynthesisinthelatterwaslessthanone-quarterthelevelseenintheregeneratinglimbs,mostlyduetolowincorporationintochondroitinsulfate.Hyaluronidaseactivity,whichappearsintheregeneratinglimbduringdifferentiationofskeletalelements(20–45days),wasnotdetectableinlimbsdenervatedearlyenoughtopreventregeneration.However,limbsdenervatedafterformationoftheblastemawillregeneratewithoutnerve,andhyaluronidaseactivityinsuchlimbswasnormal.Thus,hyaluronidaseactivityappearswhenregenerationreachesthecartilagedepositionstage,withorwithoutnerve.

[学科分类] 生物科学（综合）