Rayle D L
Department of Biology and Molecular Biology Institute, San Diego State University, CA 92182, USA.
Planta. 1989;178(1):92-5. doi: 10.1007/BF00392531.
I examined the ability of frozen-thawed Avena sativa L. coleoptile sections under applied load to extend in response to the calcium chelators ethyleneglycol-bis-(beta-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and 2-[(2-bis-[carboxymethyl]amino-5-methylphenoxy)methyl]-6-methoxy-8-bis[carboxymethyl]aminoquinoline (Quin II). Addition of 5 mM EGTA to weakly buffered (0.1 mM, pH 6.2) solutions of 2(N-morpholino) ethanesulfonic acid (Mes) initiated rapid extension and wall acidification. When the buffer strength was increased (e.g. from 20 to 100 mM Mes, pH 6.2) EGTA did not initiate extension nor did it cause wall acidification. At 5 mM Quin II failed to stimulate cell extension or wall acidification at all buffer molarities tested (0.1 to 100 mM Mes). Both chelators rapidly and effectively removed Ca2+ from Avena sections. These data indicate that Ca2+ chelation per se does not result in loosening of Avena cells walls. Rather, EGTA promotes wall extension indirectly via wall acidification.
我研究了冻融后的燕麦胚芽鞘切片在施加负荷下对钙螯合剂乙二醇双（β-氨基乙醚）-N，N，N'，N'-四乙酸（EGTA）和2-[(2-双-[羧甲基]氨基-5-甲基苯氧基)甲基]-6-甲氧基-8-双[羧甲基]氨基喹啉（喹啉II）作出反应而伸展的能力。向2（N-吗啉代）乙磺酸（MES）的弱缓冲（0.1 mM，pH 6.2）溶液中添加5 mM EGTA会引发快速伸展和细胞壁酸化。当缓冲强度增加时（例如从20 mM MES增加到100 mM MES，pH 6.2），EGTA既不会引发伸展，也不会导致细胞壁酸化。在5 mM时，喹啉II在所有测试的缓冲摩尔浓度（0.1至100 mM MES）下均未能刺激细胞伸展或细胞壁酸化。两种螯合剂都能快速有效地从燕麦切片中去除Ca2+。这些数据表明，Ca2+螯合本身并不会导致燕麦细胞壁松弛。相反，EGTA通过细胞壁酸化间接促进细胞壁伸展。
