T1 - DNA damage and repair in brain
T1 - Polymorphisms in DNA repair genes and risk of non-hodgkin lymphoma in a pooled analysis of three studies
The repair of DNA lesions via Spo11 results in a double strand break
Partially, this was proved during experiments , when the DNA preparations interplaying with a laser beam (=632.8nm ), organized in a certain way, polarize and convert the beam simultaneously into a radio-frequency range.
The hypothesis that the primary function of bacterial transformation is DNA repair was tested in the naturally transformable bacteria Bacillus subtilis and Haemophilus influenzae by determining whether competence for transformation is regulated by DNA damage. Accordingly, DNA damage was induced by mitomycin C and by ultraviolet radiation at doses that efficiently induced a known damage-inducible gene fusion, and the ability of the damaged cultures to transform was monitored. Experiments were carried out both under conditions where cells do not normally become competent and under competence-inducing conditions. No induction or enhancement of competence by damage was seen in either organism. These experiments strongly suggest that the regulation of competence does not involve a response to DNA damage, and thus that explanations other than DNA repair must be sought for the evolutionary functions of natural transformation systems.
DNA-Repair Defects and Olaparib in Metastatic Prostate Cancer
Some evidence supports our view that meiosis originated not only for DNA restoration, but also for oxidative damaged DNA repair. Assuming this, we have to regard allelic recombination as only a by-product of this process that does have other important evolutionary consequences yet is not the reason why sex is maintained. The restoration hypothesis, in contrast, provides an explanatory model for maintenance of obligate sex because of this fundamental function (Hörandl ).
In almost all apomictic plants, microsporogenesis is still present and runs without major alterations (Asker and Jerling ). Many authors report disturbances of chromosome pairing and segregation and formation of unbalanced gamete formation that often results in partly aborted pollen (Hörandl et al. ; Izmailow ; Podio et al. ). But some reduced, functional pollen is usually being produced, and there is no fundamental change in the functionality of meiosis or in male development.
How do we know that DNA replication is semi-conservative
Frequent NCOs do not support the classical hypotheses that selective forces for recombination in offspring could maintain DSB formation and crossovers during meiosis I in order to increase genetic variation in offspring. Chiasmata are required for correct segregation because they provide physical connections between homologous chromosomes during the first meiotic division. Strand invasion is required for chromosome pairing and synapsis at meiosis (Cifuentes et al. ; De Muyt et al. ; Lorenz et al. ; Page and Hawley ; Wilkins and Holliday ). However, one crossover per chromosome would suffice to serve this purpose (Cifuentes et al. ; Crismani et al. ; Lorenz et al. ). It appears inappropriate to cut DNA on 140–170 sites only to repair it afterward. Wilkins and Holliday () suggest that crossovers originated initially to limit erroneous recombination events, but this does not explain why so many DSBs occur that do not result in crossovers. Furthermore, recombination is a consequence, not a causal explanation, of meiosis. Crossovers are important for establishing the physical connection of chromosomes (synapses) for correct segregation (De Muyt et al. ).
In addition, there is evidence for a whole new type of medicine in which DNA can be influenced and reprogrammed by words and frequencies WITHOUT cutting out and replacing single genes.
Error-prone DNA repair and translesion DNA synthesis …
Error-prone DNA repair and translesion DNA synthesis ..
An overview of damage-based theories of aging, including those related to oxidative stress, protein and DNA damage.
by which cells discover DNA damage and initiate DNA repair
28/11/2017 · Unifying concept of DNA repair: The polymerase scanning hypothesis
Evolution of Sex and the DNA repair hypothesis - Science
The hypothesis of DNA repair as a main force for maintenance of meiosis, however, has not been broadly accepted
Dr GK Kogelen's DNA Repair hypothesis - well …
This argument speaks against the hypothesis of recombination as a main function, but does not provide direct evidence that meiosis is optimized for DNA repair
12/01/2018 · DNA Repair 2 - Download as PDF ..
The most astonishing experiment that was performed by Garjajev’s group is the reprogramming of the DNA codon sequences using modulated laser light.
DNA Repair and the Evolution of Longevity: A Critical Analysis
Some authors have argued that permanent diploidy would suffice to provide a homolog for HR repair, but would not require meiosis (Kondrashov ). Early eukaryotes were probably haplontic, and they needed mixis to get a second chromosome set. Meiosis was initially perhaps a tool to return to the default haploid stage. Most higher, multicellular eukaryotes have diplontic or diplohaplontic life cycles. In the long run, recessive deleterious mutations accumulate in diploid genomes, and selection will promote meiotic segregation (Otto ). Segregation at meiosis allows for a regular return to the haploid stage and thus a more efficient elimination of defect mutants among gametes or gametophytes (Hörandl ; Hörandl ). These aspects of diploid–haploid cycles, however, do not directly relate to the putative repair functions at the prophase of meiosis I, but rather support a concept that meiosis has various different DNA restoration functions (Hörandl ). Some ancient asexual animals (bdelloid rotifers) seem to have colinear chromosomes with special DNA repair mechanisms, which may also reflect a special adaptation to regular desiccation (Fischer et al. ; Schon and Martens ).
DNA Repair and the Evolution of Longevity: ..
Since the DNA was found to have a syntax and semantics akin to our human languages, it indicated that our currently restricted understanding of DNA serving only for the coding of the reproduction of proteins for the chemical make up of an organism, is only half of the story.
diploid cells can repair damaged DNA, two …
Flowering plants differentiate their germline precursors, the archespore, in the adult, diploid or polyploid sporophyte. Oxidative DNA damage in sporophytes before meiosis can be kept under control by three mechanisms. In the first, plants produce a broad array of secondary metabolites which, in concert with specific enzymes, generate a highly efficient antioxidant system that maintains a homeostasis of ROS (reactive oxygen species) elimination and overproduction (Hadacek et al. ; see below). In the second, various mitotic and non-recombinational DNA repair mechanisms are known for plants (Bleuyard et al. ). In the third, most natural oxidative stress originates in the photosynthetic organs (usually the leaves), which can be renewed regularly (Foyer and Noctor ; Halliwell ; Pfannschmidt and Yang ).
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