THE CHANGES IN CHEMICAL COMPOSITION DURING DEVELOPMENT OF THE BOVINE NUCHAL LIGAMENT
THE CHANGES IN CHEMICAL COMPOSITION DURING DEVELOPMENT OF THE BOVINE NUCHAL LIGAMENT
复制标题
牛颈韧带发育过程中化学成分的变化
作者：
E. Cleary;L. Sandberg;D. Jackson
牛颈韧带的完整或部分(在有商业价值的动物的情况下)取自45只动物(28只胎儿和17只出生后)，年龄从怀孕110天到10岁不等。以新鲜韧带为原料，采用热碱提取、碱性缓冲液多次提取、反复高压灭菌相结合的方法，定量制备了不溶性弹性蛋白。当检测成人样本时，这两种方法的不溶性残留量非常相似，但对于年轻的胎儿样本，第二种方法的值明显更高，因为弹性蛋白残留物不完全纯化。检测胶原、碱不溶性弹性蛋白和DNA浓度的变化。DNA浓度，也就是细胞密度，在胎儿发育期间逐渐下降，在出生后不久就达到一个稳定值。在弹性蛋白出现之前，胶原蛋白出现了相当多的数量，但它的浓度在出生时迅速减半。不溶性弹力蛋白在胎儿7个月末一直处于较低水平，此后开始迅速升高。在接下来的10-12周内，弹性蛋白浓度的增加率一直很高，到那时已经达到成人值。基于整个韧带的定量研究表明，细胞总含量在出生时达到最大值，但很快就下降到出生时的一半左右。总胶原蛋白的产生和弹性蛋白的沉积在从妊娠235天到出生后第一个月结束的这段时间内保持稳定的、最大的速率。因此，出生后即刻是分离可溶性前体弹力蛋白的最佳时期。
Whole bovine nuchal ligaments, or portions thereof (in the case of commercially valuable animals), were obtained from 45 animals (28 fetal and 17 postnatal) ranging in age from 110 days of gestation to 10 yr. Insoluble elastin was quantitatively prepared from the fresh ligaments by extraction with hot alkali and by a combination of multiple extractions with alkaline buffer and then repeated autoclaving. When adult samples were examined, the yields of insoluble residue by these two methods were very similar, but with young fetal samples the second method gave significantly higher values, because of incomplete purification of the elastin residue. The changes in the concentration of collagen, alkali-insoluble elastin, and DNA have been examined. DNA concentration, and, thus, cell population density, fell progressively during the fetal period of development, to reach a steady value soon after birth. Collagen appeared in appreciable quantities before elastin, but its concentration was rapidly halved at about the time of birth. Insoluble elastin concentration was low until the end of the 7th fetal month, at which time it began to rise rapidly. The rate of increase in elastin concentration remained high throughout the next 10–12 wk, by which time the adult value had been reached. Quantitative studies, on the basis of the whole ligament, showed that the total cell content rises to a maximum at birth, but falls soon after to a level about half that at birth. Total collagen production and elastin deposition continue at a steady, maximal rate over the interval from 235 days of gestation to the end of the 1st postnatal month. It is concluded that the immediate postnatal period would be the most favorable phase in which to attempt the isolation of the soluble precursor elastin.