Some aspects of glycoprotein metabolism in Acetabularia: Spatio‐temporal activity of β‐galactosidase and physiological effects of tunicamycin
作者:
ThérèseVanden Driessche,
Pascale Lause,
Jean‐Luc Guisset,
Mathews Glory,
GhislaineM. Petiau‐de Vries,
期刊:
Journal of Interdisciplinary Cycle Research
(Taylor Available online 1992)
卷期:
Volume 23,
issue 4
页码: 237-251
ISSN:0022-1945
年代: 1992
DOI:10.1080/09291019209360184
出版商: Taylor & Francis Group
关键词: Glycoprotein metabolism;Acetabularia;circadian rhythms;ß‐galactosidase;tunicamycin;morphogenesis
数据来源: Taylor
摘要:
β‐galactosidase has been chosen as an indicator of glycoprotein metabolism in Acetabularia, an unicellular and uninucleate green alga. This catabolic enzyme was quantified by fluorecence spectrometry. It was found at all developmental stages, but the activity levels differed, peaking at the end of the growth phase, at the time of cap morphogenesis initiation, β‐galactosidase activity is also subjected to periodic modulation, displaying a bimodal rhythm with a prominent peak at 16 h. The distribution of the enzyme was examined by cytochemistry, using a substrate analogue (X‐gal). It is present both in the cytoplasm and in the cell wall. No apico‐basal gradient was detectable. The physiological role of glycoproteins was assessed with tunicamycin, an inhibitor of N‐linked glycoprotein synthesis. Two pulses of 3 or 4 h of inhibitor (10 μg ml‐1) always inhibited growth, but more severely during the light period. One pulse may inhibit growth during the light period and stimulate it during the dark one; it may also have little effect, in both periods. Cap formation is inhibited between time 0 and 7. During the dark or subjective dark period, it is often stimulated or not affected. The same results were obtained in constant light. Cap formation is also inhibited in anucleate algae treated during the light period.
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