Pines M, Schickler M, Hurwitz S, Yamauchi M
Institute of Animal Science, Volcani Center, Bet Dagan, Israel.
Poult Sci. 1996 Apr;75(4):484-90. doi: 10.3382/ps.0750484.
The developmental changes in skin collagen biosynthesis pathway in male and female chickens were evaluated. Concentration of collagen, levels of mRNA for collagen type I subunits and for lysyl hydroxylase, and the level of three lysyl oxidase-derived cross-links: dehydro-dihydroxylysinonorleucine (DHLNL), dehydro-hydroxylysinonorleucine (HLNL), and dehydro-histidinohydroxymerodesmosine (HHMD) were determined during 4 wk posthatching. Skin collagen content increased with age and was higher in males than in females. In both sexes, the expression of the genes coding for alpha 1 and alpha 2 of collagen type I decreased with age: alpha 1(I) gene expression decreased from Day 3 onwards, whereas the reduction in alpha 2(I) gene expression started 1 wk later. At all ages examined, the expression of both genes was higher in male than in female skin. Males and females lysyl hydroxylase gene expression remained low until Day 16, after which an increase in the enzyme gene expression was observed. An increase in skin HLNL content was observed from Day 3 in both sexes reaching a peak in males at Day 9 and in females 1 wk later. The DHLNL content, which was higher in males than in females at all ages tested, dramatically decreased in both male and female skin from 3 d of age, reaching its lowest level at Day 16, and remained at that low level thereafter. The skin content of HHMD in males and females followed an oscillatory behavior with higher peaks in the male skin. The results suggest that the higher tensile strength of male skin than female skin may be due to the elevated skin collagen content that resulted from increased expression in collagen type I genes on the one hand, and from the higher amounts of various collagen cross-links on the other.
对雄性和雌性雏鸡皮肤胶原蛋白生物合成途径的发育变化进行了评估。在雏鸡孵化后的4周内，测定了胶原蛋白浓度、I型胶原蛋白亚基和赖氨酰羟化酶的mRNA水平，以及三种赖氨酰氧化酶衍生交联物的水平：脱氢二羟基赖氨酰正亮氨酸（DHLNL）、脱氢羟基赖氨酰正亮氨酸（HLNL）和脱氢组氨酸羟基异二肽（HHMD）。皮肤胶原蛋白含量随年龄增长而增加，且雄性高于雌性。在两性中，编码I型胶原蛋白α1和α2的基因表达随年龄下降：α1（I）基因表达从第3天开始下降，而α2（I）基因表达的下降在1周后开始。在所有检测的年龄阶段，雄性皮肤中这两个基因的表达均高于雌性。雄性和雌性的赖氨酰羟化酶基因表达在第16天之前一直较低，之后观察到该酶基因表达增加。从第3天起，两性皮肤中的HLNL含量均增加，雄性在第9天达到峰值，雌性在1周后达到峰值。在所有测试年龄中，雄性的DHLNL含量均高于雌性，从3日龄起，雄性和雌性皮肤中的DHLNL含量均急剧下降，在第16天达到最低水平，此后一直保持在该低水平。雄性和雌性皮肤中HHMD的含量呈振荡变化，雄性皮肤中的峰值更高。结果表明，雄性皮肤比雌性皮肤具有更高的抗张强度，一方面可能是由于I型胶原蛋白基因表达增加导致皮肤胶原蛋白含量升高，另一方面是由于各种胶原蛋白交联物的含量更高。
