Congenital deficiency in plasma kallikrein and kininogens in the brown Norway rat

Summary The kallikrein-kininogens-kinins system has been investigated in the brown Norway rat. In this breed the stores of kininogens in the plasma are reduced and the plasma kallikrein-like activity appears to be absent both in vivo and in vitro.Acknowledgements. The authors wish to thank Prof. M. Goffart for his excellent help in the English translation.     

Control,exploitation and tolerance of intracellular noise

Noise has many roles in biological function, including generation of errors in DNA replication leading to mutation and evolution, noise-driven divergence of cell fates, noise-induced amplification of signals, and maintenance of the quantitative individuality of cells. Yet there is order to the behaviour and development of cells. They operate within strict parameters and in many cases this behaviour seems robust, implying that noise is largely filtered by the system. How can we explain the use, rejection and sensitivity to noise that is found in biological systems? An exploration of the sources and consequences of noise calls for the use of stochastic models.