background: replacment of cd133+ cell’s β globin gene by using a gene targeting construct containing the β globin gene and essential elements for homologous recombination. materials and methods: pfbggt was amplified, then digested using the nhei and xhoi restriction enzymes, and finally, a 13.3 kb band (naked dna) was extracted from the agarose gel. biological activity of positive and negative ...

In this article we explore statistical properties of the maximum-likelihood estimates (MLEs) of the selection and mutation parameters in a Poisson random field population genetics model of directional selection at DNA sites. We derive the asymptotic variances and covariance of the MLEs and explore the power of the likelihood ratio tests (LRT) of neutrality for varying levels of mutation and sel...

The question of whether or not mergers and acquisitions have helped to enhance banks’ efficiency and profitability has not yet been conclusively resolved in the literature. We argue that this is partly due to the severe methodological problems involved. In this study, we analyze the effect of German bank mergers in the period 1995-2000 on banks’ profitability and cost efficiency. We suggest a n...

The distribution of genetic polymorphisms in a population contains information about evolutionary processes. The Poisson random field (PRF) model uses the polymorphism frequency spectrum to infer the mutation rate and the strength of directional selection. The PRF model relies on an infinite-sites approximation that is reasonable for most eukaryotic populations, but that becomes problematic whe...

Previous studies on negative selection of T cells to sheep erythrocytes in irradiated mice showed that CBA (I-Ak,I-Ek) (kk) T cells comprise two subgroups of cells restricted by I-A (A alpha-A beta) and I-A/E (E alpha-E beta) molecules. Selection of the I-A/E-restricted by I-A (A alpha-A beta) and I-A/E (E alpha-E beta) molecules. Selection of the I-A/E-restricted subset requires that the donor...

Attempts to determine or to select what kind of person or people to bring into existence are controversial. This is particularly true of “negative selection” or “selecting against” a certain type of person—that is, the attempt to prevent a person of a certain type, or people of that type, from existing. Virtually everyone agrees that some instances of negative selection are objectionable—for ex...

Creation of defined genetic mutations is a powerful method for dissecting mechanisms of bacterial disease; however, many genetic tools are only developed for laboratory strains. We have designed a modular and general negative selection strategy based on inducible toxins that provides high selection stringency in clinical Escherichia coli and Salmonella isolates. No strain- or species-specific o...

We present a maximum-likelihood method for examining the selection pressure and detecting positive selection in noncoding regions using multiple aligned DNA sequences. The rate of substitution in noncoding regions relative to the rate of synonymous substitution in coding regions is modeled by a parameter zeta. When a site in a noncoding region is evolving neutrally zeta = 1, while zeta > 1 indi...

The T cell alphabeta receptor (TCR) recognizes foreign peptide antigens bound to proteins encoded in the MHC. The MHC portion of this complex contributes much to the footprint of the TCR on the ligand, yet T cells are usually very specific for individual foreign peptides. Here, we show that the development of peptide-specific T cells is not intrinsic to thymocytes that undergo thymic-positive s...