Thymonucleic acid in Purkinje cells
Thymonucleic acid in Purkinje cells
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浦肯野细胞中的胸腺核酸
DOI：
10.1002/cne.900670304
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发表时间：
1937
期刊：
影响因子：
--
通讯作者：
Y. T. Loo
中科院分区：
文献类型：
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作者：
Y. T. Loo
根据上述观察，很明显，与某些蛋白质分子联合收割机结合形成核蛋白的胸腺核酸只存在于年轻的浦肯野细胞的细胞核中，后来也存在于老年细胞的细胞质中。随着动物年龄的增长，细胞质中的核酸趋于增加，而细胞核中的核酸趋于减少，尽管当细胞接近溶解时，这两个地方的酸最终变得微不足道。胸腺核酸或核蛋白在运动间细胞中的功能，如这里研究的浦肯野细胞，还不清楚。鉴于核蛋白在精子头部和有核细胞的染色体中含量非常丰富，我们可以假定它在细胞质的化学合成或粘附中起着某种重要作用。根据我们以前的观察（Loo，'36，' 36 a），已知核胸腺核酸或核蛋白也存在于其他高度特化类型的神经细胞中，如大脑皮层中的锥体细胞和脊髓腹角中的多极细胞;其数量似乎随着这些神经细胞的细胞质的特化程度和生长而增加。因此核蛋白的扩散（如前所述，Loo，'36）从细胞核到细胞质，细胞核中相同化合物的减少可能是细胞质过度生长的影响，另一方面可能是细胞核早期解体或衰竭的原因。下一个问题是浦肯野细胞功能和结构的特化是否会导致甚至在动物生命结束之前，它们的早期分解或死亡。40多年前，唐纳森教授（1895年）指出了导致神经细胞衰老的两个因素，即细胞体的固有结构和周围的营养条件。唐纳森教授对神经学知识做出了许多有价值的贡献，我们对此功不可没。他又说：
DISCUSSIONFrom the foregoing observations it is evident that the thymonucleic acid with which some protein molecules combine to form nucleoprotein is present only in the nucleus in young Purkinje cells, and later also in the cytoplasm in older ones. As the age of the animal advances, the nucleic acid in the cytoplasm tends to increase while that in the nucleus tends to decrease in amount, though finally the acid in both places becomes insignificant when the cell is near dissolution. The function of thymonucleic acid or nucleoprotein in interkinetic cells, like the Purkinje cells studied here, is not definitely known. In view of the fact that nucleoprotein is very abundant in the head of spermatozoa and the chromosomes of karyokinetic cells, we may assume that it plays some important part in the chemical synthesis or anabolism of the cytoplasm. From our previous observations (Loo,'36,'36 a), it is known that extranuclear thymonucleic acid or nucleoprotein is also present in other highly specialized types of nerve cells, like the pyramidal cells in the cerebral cortex and the multipolar cells in the ventral horn of the spinal cord; and its amount seems to increase with the degree of specialization and growth of the cytoplasm of such nerve cells. Thus the diffusion of nucleoprotein (as observed before, Loo,'36) from the nucleus to the cytoplasm and the diminution of the same chemical compound in the nucleus may be an effect of the overgrowth of the cytoplasm on the one hand, and may be cause of earlier disintegration or exhaustion of the nucleus on the other.The next question is whether specialization in the functions and structure of the Purkinje cells may lead to their earlier dissolution or death even before the end of the animal's life. More than 40 years ago Professor Donaldson, to whom we owe so much for his many valuable contributions to neurological knowledge, pointed out two factors for the senile dissolution of a nerve cell, the inherent constitution of the cell body and the surrounding nutrient conditions (1895). He said: