摘要:

AbstractPulse and continuous labeling with3H‐thymidine were used to examine the kinetics of cell cycle entry and progression in innervated, regenerating and denervated, nonregenerating limbs of larval axolotls. In innervated limbs the labeling index (LI) increased from a relatively low level after a pulse (30%) to 60% and 80% after 26 and 50 hr, respectively, of continuous labeling, at both preblastema and blastema stages. Thus a considerably larger proliferative fraction was revealed by continuous labeling data than was predicted from pulse labeling data. Much cycling heterogeneity was shown to exist in the blastema cell population, primarily in the G‐1 phase. These results show that many cells of regenerating limbs are transiently quiescent for periods of up to and perhaps longer than 50 hr. The proliferative fraction in denervated limbs on days 4‐6 postamputation was somewhat less than that of innervated limbs but also larger than predicted from pulse labeling data. The data show that most of the dedifferentiated cells enter the proliferative fraction even in the absence of nerves. Most of these initially cycling cells subsequently leave the proliferative fraction; the LI was less than 20% even after 50 hr of continuous labeling on days 8–10 postamp

ISSN:0022-104X    

DOI:10.1002/jez.1402330122

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractWe have tested the effect of α‐amanitin at 10, 50, and 100 μg/ ml, on precursor uptake and incorporation into poly(A)+RNA and poly(A)−RNA of mouse embryos on days 2, 3 and 4 of gestation. Embryos were pretreated with the inhibitor for 2 hr, then labeled for 2 hr in its continued presence. RNA fractions were separated by affinity chromatography on oligo(dT)‐cellulose. α‐Amanitin did not suppress uptake of RNA precursors at any of the concentrations tested in any stage. At 10 μg/ml, we could not detect any effect on incorporation into either RNA fraction in any stage. Only the highest concentration tested, 100 μg/ml, was effective in all stages in substantially suppressing incorporation into poly(A)+RNA within 2 hr. Longer treatments increased the level of suppression to a maximum of about 80%. Incorporation into poly(A)−RNA was suppressed to roughly the same extent. Despite previously reported data, it cannot be assumed that α‐amanitin at concentrations less than 100 μg/ml brings about a quick interruption of mRNA synthesis in preimplanta

ISSN:0022-104X    

DOI:10.1002/jez.1402330123

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0022-104X    

DOI:10.1002/jez.1402330101

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY