Thorsch J, Esau K
J Cell Sci. 1983 Nov;64:37-47. doi: 10.1242/jcs.64.1.37.
Nuclear crystalloids have been found in sieve elements of several Boraginaceae. Nuclei of differentiating sieve elements of Echium and other genera except Amsinckia contain one or more crystalloids composed of thin rods densely packed in parallel arrangement. After the nuclei disintegrate in the maturing sieve element the crystalloids are released into the cell lumen where they persist intact. In Amsinckia the crystalloid consists of two components: a dense component, similar to the crystalloid in the other genera and a loosely arranged paracrystalline component. The proteinaceous nature of the nuclear crystalloids and their possible similarity to P-protein was investigated by enzyme digestion techniques. Three proteolytic enzymes were employed in this study: protease, pepsin and trypsin. Successful digestion of the dense crystalloid in both Echium and Amsinckia was obtained with each enzyme tested. P-protein plugging the sieve plate pores was also digested. The loose component in Amsinckia and the aggregated and dispersed P-protein were not affected by the enzyme digestion procedures. These results seemed to indicate that the density or compactness of the proteinaceous inclusions may play a role in the differential response.
在一些紫草科植物的筛管分子中发现了核晶体。除了琴颈草属之外，蓝蓟属及其他属的正在分化的筛管分子的细胞核含有一个或多个由紧密平行排列的细杆组成的晶体。在成熟筛管分子中细胞核解体后，晶体释放到细胞腔中并保持完整。在琴颈草属中，晶体由两部分组成：一个致密部分，类似于其他属中的晶体；以及一个排列松散的类晶体部分。通过酶消化技术研究了核晶体的蛋白质性质及其与P蛋白可能的相似性。本研究使用了三种蛋白水解酶：蛋白酶、胃蛋白酶和胰蛋白酶。用每种测试的酶都成功地消化了蓝蓟属和琴颈草属中的致密晶体。堵塞筛板孔的P蛋白也被消化了。琴颈草属中的松散部分以及聚集和分散的P蛋白不受酶消化程序的影响。这些结果似乎表明，蛋白质内含物的密度或致密性可能在差异反应中起作用。
