Grass cells ingested by ruminants undergo autolysis which differs from senescence: implications for grass breeding targets and livestock production
Grass cells ingested by ruminants undergo autolysis which differs from senescence: implications for grass breeding targets and livestock production
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DOI：
10.1046/j.1365-3040.2002.00908.x
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发表时间：
2002-10-01
影响因子：
7.3
通讯作者：
Kingston-Smith, AH
中科院分区：
文献类型：
--
作者：
Beha, EM;Theodorou, MK;Kingston-Smith, AH
人们普遍认为，放牧饲料中含有的蛋白质的初始降解是由瘤胃微生物介导的，但作者最近的工作表明，植物细胞本身也导致了它们自己的死亡。本研究利用体外模拟瘤胃主应力的方法研究了多年生黑麦草叶片对瘤胃环境的响应，并排除瘤胃微生物。在与瘤胃功能相关的时间尺度上，叶片蛋白质的降解和氨基酸在组织和浴液中的积累几乎以1：1的比例发生。随着孵化时间的延长，叶绿体的形态逐渐变得更加圆整。原位定位表明，核酮糖1，5二磷酸羧化酶/加氧酶在叶绿体中被分解，细胞学判断为完整。根据这些数据，我们得出结论，植物新陈代谢可能在分解瘤胃中相对完整的细胞器中的植物蛋白质方面发挥重要作用。叶绿素含量和细胞活力的测定表明，模拟瘤胃内发生的植物过程与自然衰老过程相似，但不完全相同。
It is widely believed that the initial degradation of proteins contained in grazed forage is mediated by rumen micro-organisms, but the authors' recent work suggests that the plant cells themselves contribute to their own demise. In the present study the responses of Lolium perenne leaves to the rumen environment were investigated by using an in vitro system which simulates the main stresses of the rumen but from which rumen micro-organisms were excluded. Degradation of leaf protein and the accumulation of amino acids in tissue and bathing medium occurred over a time-scale that is relevant to rumen function, and in a near 1:1 ratio. Significant loss of nuclear material was observed after 6 h incubation and chloroplasts became morphologically more spherical as the incubation progressed. In situ localization suggested that ribulose 1,5 bisphosphate carboxylase/oxygenase was broken down within chloroplasts which from cytology were judged to be intact. We conclude from these data that plant metabolism may play a significant role in breaking down plant proteins within relatively intact organelles in the rumen. The determinations of chlorophyll content and cell viability revealed that the plant processes occurring in the simulated rumen were similar but not identical to those of natural senescence.