Involvement of Ca2+-calmodulin in Cd2+ toxicity during the early phases of radish (Raphanus sativus L) seed germination
Involvement of Ca2+-calmodulin in Cd2+ toxicity during the early phases of radish (Raphanus sativus L) seed germination
复制标题
DOI：
10.1111/j.1365-3040.1997.00072.x
复制
发表时间：
1997-05-01
影响因子：
7.3
通讯作者：
Cocucci, M
中科院分区：
文献类型：
--
作者：
Rivetta, A;Negrini, N;Cocucci, M
研究了Cd ~（2+）对萝卜（Raphanus sativus L.）研究了萝卜种子萌发及离体培养条件下Cd ~（2+）对萝卜钙调素（CaM）的影响，结果表明：萝卜种子胚轴对Cd ~（2+）有吸收，当胚轴中Cd ~（2+）含量为c. 1.1μ mol g（-1）FW.重吸收的K+，这是发芽的特点，被Cd 2+抑制，表明Cd 2+影响代谢再激活。Cd ~（2+）对胚轴皮层细胞跨膜电位的轻微影响排除了Cd ~（2+）在质膜水平上的一般毒性。孵育24 h后，Cd ~（2+）不引起总酸溶性巯基和能降低Cd ~（2+）毒性的Cd ~（2+）结合肽的增加，培养液中加入Ca ~（2+）可部分逆转Cd ~（2+）对胚轴鲜重增加的抑制作用，并同时降低Cd ~（2+）的吸收，平衡透析实验表明，Cd ~（2+）与CaM结合，并与Ca ~（2+）竞争结合。Cd ~（2+）抑制Ca ~（2+）-CaM依赖性磷酸二酯酶的激活，抑制Ca ~（2+）-CaM活性复合物的活性，降低萝卜胚轴可溶性组分中CaM与Ca ~（2+）-CaM结合酶的结合。本文讨论了Cd ~（2+）对萝卜种子萌发的毒性可能是通过Cd ~（2+）对Ca ~（2+）-CaM的作用来介导的。
The toxicity of Cd2+ in vivo during the early phases of radish (Raphanus sativus L.) seed germination and the in vitro Cd2+ effect on radish calmodulin (CaM) were studied, Cd2+ was taken up in the embryo axes of radish seeds; the increase in fresh weight of embryo axes after 24 h of incubation was inhibited significantly in the presence of 10 mmol m(-3) Cd2+ in the external medium, when the Cd2+ content in the embryo axes was c. 1.1 mu mol g(-1) FW. The reabsorption of K+, which characterizes germination, was inhibited by Cd2+, suggesting that Cd2+ affected metabolic reactivation. The slight effect of Cd2+ on the transmembrane electric potential of the cortical cells of the embryo axes excluded a generalized toxicity of Cd2+ at the plasma membrane level, After 24 h of incubation, Cd2+ induced no increase in total acid-soluble thiols and Cd2+-binding peptides able to reduce Cd2+ toxicity, Ca2+ added to the incubation medium partially reversed the Cd2+-induced inhibition of the increase in fresh weight of embryo axes and concomitantly reduced Cd2+ uptake, Equilibrium dialysis experiments indicated that Cd2+ bound to CaM and competed with Ca2+ in this binding. Cd2+ inhibited the activation of Ca2+-CaM-dependent calf-brain phosphodiesterase, inhibiting the Ca2+-CaM active complex, Cd2+ reduced the binding of CaM to the Ca2+-CaM binding enzymes present in the soluble fraction of the embryo axes of radish seeds. The possibility that Cd2+ toxicity in radish seed germination is mediated by the action of Cd2+ on Ca2+-CaM is discussed in relation to the in vivo and in vitro effects of Cd2+.