Age and previous injury were identified as the main risk factors for injury among elite football players from Iceland.

Coaches and medical support teams should pay more attention to jump and power training, as well as preventive measures and adequate rehabilitation of previous injuries to increase team success.

Yeast Rad51 recombinase has only minimal ability to form D loop. Addition of Rad54 renders D loop formation by Rad51 efficient, even when topologically relaxed DNA is used as substrate. Treatment of the nucleoprotein complex of Rad54 and relaxed DNA with topoisomerases reveals dynamic DNA remodeling to generate unconstrained negative and positive supercoils. DNA remodeling requires ATP hydrolysis by Rad54 and is stimulated by Rad51-DNA nucleoprotein complex. A marked sensitivity of DNA undergoing remodeling to P1 nuclease indicates that the negative supercoils produced lead to transient DNA strand separation. Thus, a specific interaction of Rad54 with the Rad51-ssDNA complex enhances the ability of the former to remodel DNA and allows the latter to harvest the negative supercoils generated for DNA joint formation.

Homologous recombination is crucial for the repair of DNA breaks and maintenance of genome stability. In Escherichia coli, homologous recombination is dependent on the RecA protein. In the presence of ATP, RecA mediates the homologous DNA pairing and strand exchange reaction that links recombining DNA molecules. DNA joint formation is initiated through the nucleation of RecA onto single-stranded DNA (ssDNA) to form helical nucleoprotein filaments. Two RecA-like recombinases, Rad51 and Dmc1, exist in eukaryotes. Whereas Rad51 is needed for both mitotic and meiotic recombination events, the function of Dmc1 is restricted to meiosis. Here we examine human Dmc1 protein (hDmc1) for the ability to promote DNA strand exchange, and show that hDmc1 mediates strand exchange between paired DNA substrates over at least several thousand base pairs. DNA strand exchange requires ATP and is strongly dependent on the heterotrimeric ssDNA-binding molecule replication factor A (RPA). We present evidence that hDmc1-mediated DNA recombination initiates through the nucleation of hDmc1 onto ssDNA to form a helical nucleoprotein filament. The DNA strand exchange activity of hDmc1 is probably indispensable for repair of DNA double-strand breaks during meiosis and for maintaining the ploidy of meiotic chromosomes.

No abstract

Five Rad51-like proteins, referred to as Rad51 paralogs, have been described in vertebrates. We show that two of them, Rad51B and Rad51C, are associated in a stable complex. Rad51B-Rad51C complex has ssDNA binding and ssDNA-stimulated ATPase activities. We also examined the functional interaction of Rad51B-Rad51C with Rad51 and RPA. Even though RPA enhances Rad51-catalyzed DNA joint formation via removal of secondary structure in the ssDNA substrate, it can also compete with Rad51 for binding to the substrate, leading to suppressed reaction efficiency. The competition by RPA for substrate binding can be partially alleviated by Rad51B-Rad51C. This recombination mediator function of Rad51B-Rad51C is likely required for the assembly of the Rad51-ssDNA nucleoprotein filament in vivo. Studies in Saccharomyces cerevisiae have identified a large number of genetic loci required for mitotic and meiotic recombination. These genes, comprising RAD50, RAD51, RAD52, RAD54, RAD55, RAD57, RAD59, RDH54/TID1, MRE11, and XRS2 are collectively known as the RAD52 epistasis group. The RAD52 group of genes are also intimately involved in the repair of DNA double-strand breaks induced by exogenous agents such as ionizing radiation (Paques and Haber 1999;Sung et al. 2000) and for telomere maintenance in the absence of telomerase.Cloning, genetic, and biochemical studies have indicated that the structure and function of the RAD52 group genes are highly conserved among eukaryotes, from yeast to humans Thompson and Schild 2001). Interestingly, in mammals, the efficiency of recombination and DNA double-strand break repair is contingent upon the integrity of the tumor suppressors BRCA1 and BRCA2 (Dasika et al. 1999;Moynahan et al. 1999Moynahan et al. , 2001Thompson and Schild 2001), underscoring the importance for deciphering the mechanistic basis of the recombination machinery.In recombination processes that involve the formation of a DNA double-strand break, the ends of the DNA break are processed to yield single-stranded DNA tails. These DNA tails are utilized by the RAD52 group recombination factors for the formation of DNA joints with a homologous DNA template, contained within the sister chromatid or the chromosomal homolog. The nascent DNA joints are then extended in length by branch migration, followed by resolution of DNA intermediates to complete the recombination process (Paques and Haber 1999;Sung et al. 2000).The RAD51 encoded product is the functional homolog of Escherichia coli RecA protein, and like RecA, possesses the ability to promote the homologous DNA pairing and strand exchange reaction that forms heteroduplex DNA joints. In mediating homologous DNA pairing and strand exchange, Rad51 must first assemble onto ssDNA as a nucleoprotein filament, in which the DNA is held in a highly extended conformation (Ogawa et al. 1993;Benson et al. 1994;Sung and Robberson 1995). Assembly of the Rad51-ssDNA nucleoprotein filament is rate-limiting and strongly inhibited by secondary structure in the ssDNA template. The removal of seconda...

The IVCT for diagnosis of MH susceptibility in Europe has a high sensitivity and a satisfactory specificity.

Until recently, it was generally assumed that essentially all regulation of transcription takes place via regions adjacent to the coding region of a gene--namely promoters and enhancers--and that, after recruitment to the promoter, the polymerase simply behaves like a machine, quickly "reading the gene." However, over the past decade a revolution in this thinking has occurred, culminating in the idea that transcript elongation is extremely complex and highly regulated and, moreover, that this process significantly affects both the organization and integrity of the genome. This review addresses basic aspects of transcript elongation by RNA polymerase II (RNAPII) and how it relates to other DNA-related processes.