DNA base damage by reactive oxygen species, oxidizing agents, and UV radiation.

Emphasis has been placed in this article dedicated to DNA damage on recent aspects of the formation and measurement of oxidatively generated damage in cellular DNA in order to provide a comprehensive and updated survey. This includes single pyrimidine and purine base lesions, intrastrand cross-links, purine 5',8-cyclonucleosides, DNA-protein adducts and interstrand cross-links formed by the reactions of either the nucleobases or the 2-deoxyribose moiety with the hydroxyl radical, one-electron oxidants, singlet oxygen, and hypochlorous acid. In addition, recent information concerning the mechanisms of formation, individual measurement, and repair-rate assessment of bipyrimidine photoproducts in isolated cells and human skin upon exposure to UVB radiation, UVA photons, or solar simulated light is critically reviewed.

Dual role of p53 amyloid formation in cancer; loss of function and gain of toxicity.

The tumor suppressor p53 plays an important role in genome integrity. It is frequently mutated in all types of human cancers, making p53 a key factor in cancer progression. Two phenotypic consequences of these alterations are dominant; a loss of function and a gain of function of p53, which, in several cases, accumulates in intracellular aggregates.

Post-meiotic intra-testicular sperm senescence in a wild vertebrate.

There is growing interest in sperm senescence, both in its underlying mechanisms and evolutionary consequences, because it can impact the evolution of numerous life history traits. Previous studies have documented various types of sperm senescence, but evidence of post-meiotic intra-testicular sperm senescence in wild animals is lacking. To assess such senescence, we studied within-season changes in sperm motility in the common toad (Bufo bufo), where males produce all sperm prior to the breeding season.

Radiation-induced formation of 2',3'-dideoxyribonucleosides in DNA: a potential signature of low-energy electrons.

We have identified a series of modifications of the 2'-deoxyribose moiety of DNA arising from the exposure of isolated and cellular DNA to ionizing radiation. The modifications consist of 2',3'-dideoxyribonucleoside derivatives of T, C, A, and G, as identified by enzymatic digestion and LC-MS/MS. Under dry conditions, the yield of these products was 6- to 44-fold lower than the yield of 8-oxo-7,8-dihydroguanine.

The channel-forming Sym1 protein is transported by the TIM23 complex in a presequence-independent manner.

The majority of multispanning inner mitochondrial membrane proteins utilize internal targeting signals, which direct them to the carrier translocase (TIM22 complex), for their import. MPV17 and its Saccharomyces cerevisiae orthologue Sym1 are multispanning inner membrane proteins of unknown function with an amino-terminal presequence that suggests they may be targeted to the mitochondria. Mutations affecting MPV17 are associated with mitochondrial DNA depletion syndrome (MDDS).

A high resolution electro-optical approach for investigating transition of soluble proteins to integral membrane proteins probed by colicin A.

The transition from water soluble state to an integral membrane protein state is a crucial step in the formation of the active form of many pore-forming or receptor proteins. Albeit this, high resolution techniques which allow assay of protein membrane binding and concomitant development of the final active form in the membrane await further development. Here, we describe a horizontal artificial bilayers setup allowing for simultaneous electrical and optical measurements at a single molecule level.

Cancer radiotherapy based on femtosecond IR laser-beam filamentation yielding ultra-high dose rates and zero entrance dose.

Since the invention of cancer radiotherapy, its primary goal has been to maximize lethal radiation doses to the tumor volume while keeping the dose to surrounding healthy tissues at zero. Sadly, conventional radiation sources (γ or X rays, electrons) used for decades, including multiple or modulated beams, inevitably deposit the majority of their dose in front or behind the tumor, thus damaging healthy tissue and causing secondary cancers years after treatment. Even the most recent pioneering advances in costly proton or carbon ion therapies can not completely avoid dose buildup in front of the tumor volume.

Writing Quality in Chinese Children: Speed and Fluency Matter.

There were two goals of the present study. The first was to create a scoring scheme by which 9-year-old Chinese children's writing compositions could be rated to form a total score for writing quality. The second was to examine cognitive correlates of writing quality at age 9 from measures administered at ages 6-9.

The mitochondrial oxidase assembly protein1 (Oxa1) insertase forms a membrane pore in lipid bilayers.

The inner membrane of mitochondria is especially protein-rich. To direct proteins into the inner membrane, translocases mediate transport and membrane insertion of precursor proteins. Although the majority of mitochondrial proteins are imported from the cytoplasm, core subunits of respiratory chain complexes are inserted into the inner membrane from the matrix.

Fundamental mechanisms of DNA radiosensitization: damage induced by low-energy electrons in brominated oligonucleotide trimers.

The replacement of nucleobases with brominated analogs enhances DNA radiosensitivity. We examine the chemistry of low-energy electrons (LEEs) in this sensitization process by experiments with thin films of the oligonucleotide trimers TBrXT, where BrX = 5-BrU (5-bromouracil), 5-BrC (5-bromocytosine), 8-BrA (8-bromoadenine), or 8-BrG (8-bromoguanine). The products induced from irradiation of thin (∼ 2.

Bacterial origin of a mitochondrial outer membrane protein translocase: new perspectives from comparative single channel electrophysiology.

Mitochondria are of bacterial ancestry and have to import most of their proteins from the cytosol. This process is mediated by Tom40, an essential protein that forms the protein-translocating pore in the outer mitochondrial membrane. Tom40 is conserved in virtually all eukaryotes, but its evolutionary origin is unclear because bacterial orthologues have not been identified so far.

Developmental relations between reading fluency and reading comprehension: a longitudinal study from Grade 1 to Grade 2.

From a developmental framework, relations among list reading fluency, oral and silent reading fluency, listening comprehension, and reading comprehension might be expected to change as children's reading skills develop. We examined developmental relations among these constructs in a latent-variable longitudinal study of first and second graders. Results showed that list reading fluency was uniquely related to reading comprehension in Grade 1, but not in Grade 2, after accounting for text reading fluency (oral or silent) and listening comprehension.

Profiling cytosine oxidation in DNA by LC-MS/MS.

Spontaneous and oxidant-induced damage to cytosine is probably the main cause of CG to TA transition mutations in mammalian genomes. The reaction of hydroxyl radical (·OH) and one-electron oxidants with cytosine derivatives produces numerous oxidation products, which have been identified in large part by model studies with monomers and short oligonucleotides. Here, we developed an analytical method based on LC-MS/MS to detect 10 oxidized bases in DNA, including 5 oxidation products of cytosine.

Reduction in predator defense in the presence of neighbors in a colonial fish.

Predation pressure has long been considered a leading explanation of colonies, where close neighbors may reduce predation via dilution, alarming or group predator attacks. Attacking predators may be costly in terms of energy and survival, leading to the question of how neighbors contribute to predator deterrence in relationship to each other. Two hypotheses explaining the relative efforts made by neighbors are byproduct-mutualism, which occurs when breeders inadvertently attack predators by defending their nests, and reciprocity, which occurs when breeders deliberately exchange predator defense efforts with neighbors.

Infiltration of glioma cells in brain parenchyma stimulated by radiation in the F98/Fischer rat model.

Purpose: In the months following radiotherapy, a rapid recurrence of glioblastoma multiforme occurs in the periphery of the resection cavity. The aim of this study was to assess the contribution of irradiation of the brain in the infiltration profile of glioma cells.

Material And Methods: Using the F98/Fischer rat glioma model, we either irradiated the brain, the F98 cancer cells, or both to separately investigate the effects of radiation.

Specific DNA duplex formation at an artificial lipid bilayer: towards a new DNA biosensor technology.

A novel technique is described which comprises a base-specific DNA duplex formation at a lipid bilayer-H(2) O-phase boundary layer. Two different probes of oligonucleotides both carrying a double-tailed lipid at the 5'-terminus were incorporated into stable artificial lipid bilayers separating two compartments (cis/trans-channel) of an optically transparent microfluidic sample carrier with perfusion capabilities. Both the cis- and trans-channels are filled with saline buffer.

Componential skills of beginning writing: An exploratory study.

The present study examined the components of end of kindergarten writing, using data from 242 kindergartners. Specifically of interest was the importance of spelling, letter writing fluency, reading, and word- and syntax-level oral language skills in writing. The results from structural equation modeling revealed that oral language, spelling, and letter writing fluency were positively and uniquely related to writing skill after accounting for reading skills.

Biologically relevant oxidants and terminology, classification and nomenclature of oxidatively generated damage to nucleobases and 2-deoxyribose in nucleic acids.

A broad scientific community is involved in investigations aimed at delineating the mechanisms of formation and cellular processing of oxidatively generated damage to nucleic acids. Perhaps as a consequence of this breadth of research expertise, there are nomenclature problems for several of the oxidized bases including 8-oxo-7,8-dihydroguanine (8-oxoGua), a ubiquitous marker of almost every type of oxidative stress in cells. Efforts to standardize the nomenclature and abbreviations of the main DNA degradation products that arise from oxidative pathways are reported.

Modeling the development of written language.

Alternative models of the structure of individual and developmental differences of written composition and handwriting fluency were tested using confirmatory factor analysis of writing samples provided by first- and fourth-grade students. For both groups, a five-factor model provided the best fit to the data. Four of the factors represented aspects of written composition: macro-organization (use of top sentence and number and ordering of ideas), productivity (number and diversity of words used), complexity (mean length of T-unit and syntactic density), and spelling and punctuation.

Rapid serial naming and reading ability: the role of lexical access.

Rapid serial naming tasks are frequently used to explain variance in reading skill. However, the construct being measured by rapid naming is yet undetermined. The Phonological Processing theory suggests that rapid naming relates to reading because of similar demands of access to long-term stored phonological representations of visual stimuli.

Exploring novelty: a component trait of behavioural syndromes in a colonial fish.

Individual differences in exploratory behaviour have been shown to be consistent across contexts and suggested to be part of behavioural syndromes in a diversity of species, including fish. Exploration has also been shown to be a key factor in understanding complex ecological processes such as sexual selection and cooperation. Another important question in ecology is why animals breed in colonies.

Predictive value of margins in diagnostic biopsies of nonmelanoma skin cancers.

Background: With geographic regional variation, nonmelanoma skin cancer biopsy reports include assessment of margins. When margins are reported as negative, clinical dilemmas may emerge concerning the necessity of additional treatment.

Objective: To evaluate the predictive value of biopsy margins with regard to residual tumor present in subsequent excisions of nonmelanoma skin cancers.

Porcine xenograft biosynthetic wound dressings for the management of postoperative Mohs wounds.

Cadaveric allografts and a large variety of other biologic dressings have been reported as being useful for the postoperative management of Mohs micrographic surgery (MMS) wounds. Although the use of porcine xenografts for the immediate postoperative management of these wounds is known, their use has not been detailed in the dermatology literature. A case series of 15 consecutive Mohs micrographic surgery patients (mean age = 74.

Low-energy electron-induced damage in a trinucleotide containing 5-bromouracil.

The reaction of low-energy electrons (LEEs; 10 eV) with 5'-TpXpT-3' (TXT), where X is uracil (U), thymine (T), and 5-bromouracil (5BrU), was examined by HPLC-UV analysis. The presence of 5BrU increased total damage by >50%. The radiation products of T5BrUT included TUT (40%), free U, T, 5BrU (23%), and fragments (13%).