Correlates of substitution rate variation in mammalian protein-coding sequences

Background  

Rates of molecular evolution in different lineages can vary widely, and some of this variation might be predictable from aspects of species' biology. Investigating such predictable rate variation can help us to understand the causes of molecular evolution, and could also help to improve molecular dating methods. Here we present a comprehensive study of the life history correlates of substitution rate variation across the mammals, comparing results for mitochondrial and nuclear loci, and for synonymous and non-synonymous sites. We use phylogenetic comparative methods, refined to take into account the special nature of substitution rate data. Particular attention is paid to the widespread correlations between the components of mammalian life history, which can complicate the interpretation of results.     

Improved Large-Scale Preparation of Phage T4 Endonuclease VII Overexpressed in E. coli

Using PCR, we cloned T4 gene 49, which encodes the endonucleaseVII, and the inactive mutant gene 49 amE727 into vector pET-11a.In combination with Escherichia coli host strain BL21(DE3),this system provided excellent repression of the expressionof the highly toxic protein before induction with IPTG. Afterinduction, the proteins were made in high quantities while remainingsoluble. Dilution of the crude lysate at 1 : 10,000 continuedto show a highly specific activity in the case of the wild-typeenzyme. The protein was purified to homogeneity with a recoveryof 33% using two chromatography steps. The yield was 20 timeshigher and the specific activity 500 times higher than thatobtained by using the previously published protocol.