Altered proteostasis in aging and heat shock response in C. elegans revealed by analysis of the global and de novo synthesized proteome

Protein misfolding and aggregation as a consequence of impaired protein homeostasis (proteostasis) not only characterizes numerous age-related diseases but also the aging process itself. Functionally related to the aging process are, among others, ribosomal proteins, suggesting an intimate link between proteostasis and aging. We determined by iTRAQ quantitative proteomic analysis in C. elegans how the proteome changes with age and in response to heat shock. Levels of ribosomal proteins and mitochondrial chaperones were decreased in aged animals, supporting the notion that proteostasis is altered during aging. Mitochondrial enzymes of the tricarboxylic acid cycle and the electron transport chain were also reduced, consistent with an age-associated energy impairment. Moreover, we observed an age-associated decline in the heat shock response. In order to determine how protein synthesis is altered in aging and in response to heat shock, we complemented our global analysis by determining the de novo proteome. For that, we established a novel method that enables both the visualization and identification of de novo synthesized proteins, by incorporating the non-canonical methionine analogue, azidohomoalanine (AHA), into the nascent polypeptides, followed by reacting the azide group of AHA by ‘click chemistry’ with an alkyne-labeled tag. Our analysis of AHA-tagged peptides demonstrated that the decreased abundance of, for example, ribosomal proteins in aged animals is not solely due to degradation but also reflects a relative decrease in their synthesis. Interestingly, although the net rate of protein synthesis is reduced in aged animals, our analyses indicate that the synthesis of certain proteins such as the vitellogenins increases with age.     

雅可比矩阵在机器人运动中的应用

利用雅可比矩阵的性质研究机器人的逆运动问题,特别地讨论了带冗余度和矩阵奇异的情形.首先给出逆运动的求解方法,然后给出它的应用,用梯度下降法给出关节角的迭代公式,最后给出模拟仿真结果.仿真结果表明该方法准确高效,为机器人的运动规划和控制的实现奠定基础.      

Riccati方程的几何求解方法

本文首先介绍线性系统的最优控制概念,引入经典的Riccati方程. 之后,在4种不同的黎曼度量下给出正定矩阵流形上的测地距离. 最后,利用几何方法求出对应的黎曼梯度,给出了关于测地距离的求解Riccati方程的迭代公式.      

双体量子系统的算子权并发度

在Hilbert空间算子理论基础上,通过量子态的约化密度矩阵给出了双体量子系统中算子权并发度的定义,并讨论了其在判断量子态可分性上的有效性.同时研究了此类加权并发度和系统信道的相容性及相关性质.      

正定矩阵流形上的系统控制算法

非线性问题出现在多个领域，如何处理非线性问题是科学工作者们关注的热点.本文针对控制系统的结构和控制问题，利用正定矩阵流形上的几何结构，设计出一个以正定矩阵为输出的控制系统.为使得系统输出尽可能接近相应的指标，根据不同的度量结构设计出相应的自然梯度算法，实验结果验证了算法的有效性.