用焦锑酸钾沉淀的电镜细胞化学方法研究低温胁迫下龙眼(Dimocarpus longana Lour.)幼叶细胞内Ca²⁺水平的变化。未经低温处理的幼叶,细胞壁、细胞间隙、质膜和液泡存在大量的Ca²⁺沉淀颗粒,叶绿体、细胞质和细胞核中也有一些Ca²⁺沉淀颗粒分布,表明液泡和细胞间隙是植物细胞的钙库。龙眼幼叶经4℃44h处理后,质膜上Ca²⁺沉淀颗粒明显增多,细胞质和细胞核中的Ca²⁺水平增加。不抗寒品种在低温胁迫下核膜开口,有时可观察到核内容物外漏。抗寒品种叶绿体中类囊体不形成基粒,少数片层结合重叠后伸展在整个叶绿体中。而不抗寒品种类囊体则堆积成明显的颗粒状基粒,片层数量较多,且叶绿体多数成蝶型排列。

The changes of Ca²⁺ localization in cells of longan (Dimocarpus longana Lour .) leaflets under chilling stress were investigated with calcium antimonate precipitate-electromicroscopic cytochemical methods .When longan leaflets grew at the optimum temperature , it w as shown that the deposits of calcium antimonate , being the indicator for Ca²⁺ localization , mainly concentrated within the vacuoles and intercellular spaces , and that there w as also some Ca²⁺ deposits in plastid , mitochondria , cytoplasm and nucleus .This indicates that under the normal condition , the vacuoles are the main pool of Ca^{2 +} , and that there is quite an amount of Ca²⁺ in the intercellular spaces .On the contrary , the free Ca²⁺ in cy toplasm and nucleus is very low under the normal condition .When the long an leaflet was treated at the temperature of 4 ℃ for 44 hours , the level of Ca²⁺ in cytoplasm and nucleus increased considerably . When the chilling stress occurs , a great amount of Ca²⁺ deposits in vacuole and chloroplast .The membrane of nucleus in the cold sensible variety had been damaged and some nuclear substances let out .There w ere some stroma thylakoids in the cells of cold resistant variety , while many basal granules in the cold sensible variety .The membrane of chloroplasts had been damaged .The chloroplasts appear as butterfly-style. in the cells of cold sensible variety .