Dark production of reactive oxygen species in photosystem II membrane particles at elevated temperature: EPR spin-trapping study

In our study, EPR spin-trapping technique was employed to study dark production of two reactive oxygen species, hydroxyl radicals (OH.) and singlet oxygen ((1)O2), in spinach photosystem II (PSII) membrane particles exposed to elevated temperature (47 degrees C). Production of OH., evaluated as EMPO-OH adduct EPR signal, was suppressed by the enzymatic removal of hydrogen peroxide and by the addition of iron chelator desferal, whereas externally added hydrogen peroxide enhanced OH. production. These observations reveal that OH. is presumably produced by metal-mediated reduction of hydrogen peroxide in a Fenton-type reaction. Increase in pH above physiological values significantly stimulated the formation of OH., whereas the presence of chloride and calcium ions had the opposite effect. Based on our results it is proposed that the formation of OH. is linked to the thermal disassembly of water-splitting manganese complex on PSII donor side. Singlet oxygen production, followed as the formation of nitroxyl radical TEMPO, was not affected by OH. scavengers. This finding indicates that the production of these two species was independent and that the production of (1)O2 is not closely linked to PSII donor side.     

Genetic admixture, adipocytokines, and adiposity in Black Americans: the Health, Aging, and Body Composition study

Adipocytokines are a subset of cytokines produced by adipose tissue and are associated with risk of type II diabetes and atherosclerosis. Levels of adipocytokines differ between Black and White Americans, even after adjustment for differences in adiposity, diseases associated with adipocytokines including type 2 diabetes and cardiovascular disease, and general socioeconomic status indicators such as income. We used a series of ancestry informative markers to estimate genetic ancestry in a population-based study of older Black Americans, and examined the association between genetic ancestry and adipocytokines and soluble receptors to help determine which of these may be most amenable to admixture mapping. We typed 35 ancestry informative markers in 1,241 self-reported Black Americans with available DNA from the Health, Aging, and Body Composition (Health ABC) study with available DNA and used a maximum likelihood approach to estimate percent European ancestry. We used linear regression models to determine the association between these adipocytokines and percent ancestry, and staged models to examine whether adiposity or other measures affected the associations of genetic ancestry and adipocytokines. Mean European ancestry was 22.3 ± 15.9%. In multivariate adjusted models, the strongest associations observed were between higher European ancestry and interleukin-6 soluble receptor (IL-6 SR), C-reactive protein (CRP), and adiponectin levels, with interleukin-2 soluble receptor (IL-2 SR) and soluble tumor necrosis factor receptor II (TNF-α SR II) also showing more modest but significant associations. The association with adiponectin became stronger after adjustment for adiposity. These novel findings suggest that admixture mapping may identify genetic factors influencing the levels of IL-6 SR, CRP, IL-2 SR, and adiponectin. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Influence of the "Rijeka model" of bioethics education on attitudes of medical students towards death and dying--a cross sectional study

The aim of this study was to assess attitude towards euthanasia, and the influence of socio-demographic data and death education carried out through the "Rijeka model" of bioethics education for the first-year medical students of the School of Medicine, University of Rijeka, Croatia. The cross-sectional study was conducted in the academic year 20031 2004. 124 (61% female) participants were surveyed by using an anonymous questionnaire before and after training. Catholics (p = 0.003) and students from areas with populations of less than 50,000 inhabitants (p = 0.001) had significantly negative attitude towards euthanasia than others before the course, yet no differences were found following this training. Attitude towards euthanasia was significantly positive after the course (p = 0.005). All items in the questionnaire, except "Croatia should legalise euthanasia", received more positive scores after the course. Death education carried through the "Rijeka model" of bioethics education has changed attitudes of medical students towards a more positive perception of euthanasia.     

Intravitreal bevacizumab (Avastin) in treatment of neovascular age-related macular degeneration

To evaluate the efficacy and safety of intravitreal bevacizumab in treatment of minimally classic and occult choroidal neovascularization secondary to age-related macular disease 48 eyes of 48 patients (mean age of 74.8) included in this prospective, noncomparative, interventional case series. Median follow-up was 18 weeks (6-24). Intravitreal bevacizumab injection of 0.05 mL (1.25 mg) was administered at baseline and in 6 week intervals until leakage resolved, and repeated in case of leakage recurrence. Visual acuity (VA) improved in the majority of patients (mean baseline VA = 1.078 log MAR) by mean increase of 1.32 lines (last follow-up) (p = 0.001). Central foveal thickness and total macular volume decreased by 51 microm (p = 0.01) and 0.84 mm3 (p < 0.0001) respectively. No serious complications were observed. As initial therapy, intravitreal bevacizumab appears to be safe and effective. A significant functional and anatomical improvement was noted in majority of patients and maintained during follow-up.     

Incorporating evolutionary based tools in cephalopod fisheries management

Reviews in Fish Biology and Fisheries - With gradual decline of global finfish resources, fisheries targeting cephalopods expanded. Yet, the stock assessment and management practice are frequently...     

Fusion of Protein Aggregates Facilitates Asymmetric Damage Segregation

Asymmetric segregation of damaged proteins at cell division generates a cell that retains damage and a clean cell that supports population survival. In cells that divide asymmetrically, such as Saccharomyces cerevisiae, segregation of damaged proteins is achieved by retention and active transport. We have previously shown that in the symmetrically dividing Schizosaccharomyces pombe there is a transition between symmetric and asymmetric segregation of damaged proteins. Yet how this transition and generation of damage-free cells are achieved remained unknown. Here, by combining in vivo imaging of Hsp104-associated aggregates, a form of damage, with mathematical modeling, we find that fusion of protein aggregates facilitates asymmetric segregation. Our model predicts that, after stress, the increased number of aggregates fuse into a single large unit, which is inherited asymmetrically by one daughter cell, whereas the other one is born clean. We experimentally confirmed that fusion increases segregation asymmetry, for a range of stresses, and identified Hsp16 as a fusion factor. Our work shows that fusion of protein aggregates promotes the formation of damage-free cells. Fusion of cellular factors may represent a general mechanism for their asymmetric segregation at division.     

X Chromosome Control of Meiotic Chromosome Synapsis in Mouse Inter-Subspecific Hybrids

Hybrid sterility (HS) belongs to reproductive isolation barriers that safeguard the integrity of species in statu nascendi. Although hybrid sterility occurs almost universally among animal and plant species, most of our current knowledge comes from the classical genetic studies on Drosophila interspecific crosses or introgressions. With the house mouse subspecies Mus m. musculus and Mus m. domesticus as a model, new research tools have become available for studies of the molecular mechanisms and genetic networks underlying HS. Here we used QTL analysis and intersubspecific chromosome substitution strains to identify a 4.7 Mb critical region on Chromosome X (Chr X) harboring the Hstx2 HS locus, which causes asymmetrical spermatogenic arrest in reciprocal intersubspecific F1 hybrids. Subsequently, we mapped autosomal loci on Chrs 3, 9 and 13 that can abolish this asymmetry. Combination of immunofluorescent visualization of the proteins of synaptonemal complexes with whole-chromosome DNA FISH on pachytene spreads revealed that heterosubspecific, unlike consubspecific, homologous chromosomes are predisposed to asynapsis in F1 hybrid male and female meiosis. The asynapsis is under the trans- control of Hstx2 and Hst1/Prdm9 hybrid sterility genes in pachynemas of male but not female hybrids. The finding concurred with the fertility of intersubpecific F1 hybrid females homozygous for the Hstx2^Mmm allele and resolved the apparent conflict with the dominance theory of Haldane''s rule. We propose that meiotic asynapsis in intersubspecific hybrids is a consequence of cis-acting mismatch between homologous chromosomes modulated by the trans-acting Hstx2 and Prdm9 hybrid male sterility genes.     

Real-Time Imaging of DNA Damage in Yeast Cells Using Ultra-Short Near-Infrared Pulsed Laser Irradiation

Analysis of accumulation of repair and checkpoint proteins at repair sites in yeast nuclei has conventionally used chemical agents, ionizing radiation or induction of endonucleases to inflict localized damage. In addition to these methods, similar studies in mammalian cells have used laser irradiation, which has the advantage that damage is inflicted at a specific nuclear region and at a precise time, and this allows accurate kinetic analysis of protein accumulation at DNA damage sites. We show here that it is feasible to use short pulses of near-infrared laser irradiation to inflict DNA damage in subnuclear regions of yeast nuclei by multiphoton absorption. In conjunction with use of fluorescently-tagged proteins, this allows quantitative analysis of protein accumulation at damage sites within seconds of damage induction. PCNA accumulated at damage sites rapidly, such that maximum accumulation was seen approximately 50 s after damage, then levels declined linearly over 200–1000 s after irradiation. RPA accumulated with slower kinetics such that hardly any accumulation was detected within 60 s of irradiation, and levels subsequently increased linearly over the next 900 s, after which levels were approximately constant (up to ca. 2700 s) at the damage site. This approach complements existing methodologies to allow analysis of key damage sensors and chromatin modification changes occurring within seconds of damage inception.