The chromosomal replication origin of the plasmidless derivative (TK21) from Streptomyces lividans 66 has been cloned as an autonomously replicating minichromosome (pSOR1) by using the thiostrepton resistance gene as a selectable marker. pSOR1 could be recovered as a closed circular plasmid which shows high segregational instability. pSOR1 was shown to replicate in Streptomyces coelicolor A3(2)...

Falkow, Stanley (Walter Reed Army Institute of Research, Washington, D.C.), H. Schneider, L. S. Baron, and S. B. Formal. Virulence of Escherichia-Shigella hybrids for the guinea pig. J. Bacteriol. 86:1251-1258. 1963.-Genetic recombination studies between donor Escherichia coli and recipient Shigella flexneri 2a strains were employed to examine alterations in the virulence of Shigella hybrids fo...

Recent studies report a surprisingly high degree of marker-to-marker linkage disequilibrium (LD) in ruminant livestock populations. This has important implications for QTL mapping and marker-assisted selection. This study evaluated LD between microsatellite markers in a number of breeding populations of layer chickens using the standardized chi-square (chi(2')) measure. The results show appreci...

The genetic basis of fitness reduction associated with inbreeding is still poorly understood. Here we use associations between allozyme genotypes and fitness to investigate the genetic basis of inbreeding depression in experimental outdoor populations of the water flea, Daphnia magna. In Daphnia, a phase of clonal reproduction follows hatching from sexually produced resting eggs, and changes in...

Achieving the capacity to detect minimal numbers of neoplastic cells is a major cancer diagnostic challenge. Chromosomal translocations such as the t(14;18)(q32;q21) found in follicular and some nonfollicular lymphomas provide a tumor-specific molecular marker. The 14;18 breakpoints are focused at one of six immunoglobulin heavy chain joining (JH) regions on chromosome 14 and a small major brea...

in the retrospective investigation titled “risk factors evaluation of threshold retinopathy of prematurity” at a tertiary ophthalmic center in tehran, iran, the authors have studied 859 premature neonates during one year (2008-2009). 791 eyes have had retinopathy of prematurity (rop) and 7.4% of them presented threshold retinopathy (trop). the investigators aim has been to present and compare t...

Transformation-associated recombination (TAR) is a cloning technique that allows specific chromosomal regions or genes to be isolated directly from genomic DNA without prior construction of a genomic library. This technique involves homologous recombination during spheroplast transformation between genomic DNA and a TAR vector that has 5' and 3' gene targeting sequences (hooks). Typically, TAR ...

Objective Approximately 15 percent of couples are infertile. The male factor is responsible for approximately 50% of the cases. One of the main genetic factors playing a role in male infertility is Y chromosomal microdeletion within the proximal long arm of the Y chromosome (Yq11), named azoospermia factor (AZF) region. Recent studies have also demonstrated that there is a potential connection ...