ASSEMBLY AND DISASSEMBLY OF AXONAL MICROTUBULES OF THE TOAD XENOPUS-LAEVIS UNDER THE EFFECT OF TEMPERATURE

ALVAREZ, J; FADIC, R

Abstract

In toads Xenopus laevis living at 11-degrees (winter), the microtubular density of 4-mum myelinated axons of lumbosacral nerves was assessed with the electron microscope. In controls, the density was 11.2 microtubules/mum2. In nerves incubated at 0-degrees, microtubules decreased following a simple exponential curve with a half time of 4.7 min (k = 0.149 min-1); residual microtubules were 4.5%. After rewarming, the full complement of microtubules reappeared within 60 min. In steady state, the microtubular density exhibited a linear relationship with temperature (range: 0-22-degrees; slope 0.94 microtubules/mum2 per degree; r, 0.96). After heating the nerve by 11-degrees above the physiological temperature, microtubules increased by 83%, whereby the pool of unpolymerized tubulin was at least 2.7 mg/ml of axoplasm. A seasonal variation of the microtubular density was observed which accorded with the environmental temperature. The macroscopic kinetics of microtubule disassembly in the axoplasm is similar to that reported for purified tubulin but that of assembly is slower. Microtubules of peripheral axons of Xenopus are cold-labile and vary during the annual cycle.

Más información

Título según WOS: ID WOS:A1992JZ32400004 Not found in local WOS DB
Título de la Revista: JOURNAL OF EXPERIMENTAL ZOOLOGY
Volumen: 264
Número: 3
Editorial: WILEY-LISS
Fecha de publicación: 1992
Página de inicio: 261
Página final: 266
DOI:

10.1002/jez.1402640305

Notas: ISI