Short- and long-term effects of 56Fe irradiation on cognition and hippocampal DNA methylation and gene expression.

BackgroundAstronauts are exposed to 56Fe ions that may pose a significant health hazard during and following prolonged missions in deep space. We showed previously that object recognition requiring the hippocampus, a structure critical for cognitive function, is affected in 2-month-old mice irradiated with 56Fe ions. Here we examined object recognition in 6-month-old mice irradiated with 56Fe ions, a biological age more relevant to the typical ages of astronauts. Moreover, because the mechanisms mediating the detrimental effects of 56Fe ions on hippocampal function are unclear, we examined changes in hippocampal networks involved in synaptic plasticity and memory, gene expression, and epigenetic changes in cytosine methylation (5mC) and hydroxymethylation (5hmC) that could accompany changes in gene expression. We assessed the effects of whole body 56Fe ion irradiation at early (2 weeks) and late (20 weeks) time points on hippocampus-dependent memory and hippocampal network stability, and whether these effects are associated with epigenetic changes in hippocampal DNA methylation (both 5mC and 5hmC) and gene expression.ResultsAt the two-week time point, object recognition and network stability were impaired following irradiation at the 0.1 and 0.4 Gy dose, but not following irradiation at the 0.2 Gy dose. No impairments in object recognition or network stability were seen at the 20-week time point at any irradiation dose used. Consistent with this pattern, the significance of pathways for gene categories for 5hmC was lower, though not eliminated, at the 20-week time point compared to the 2-week time point. Similarly, significant changes were observed for 5mC gene pathways at the 2-week time point, but no significant gene categories were observed at the 20-week time point. Only the 5hmC changes tracked with gene expression changes.ConclusionsDose- and time-dependent epigenomic remodeling in the hippocampus following 56Fe ion exposure correlates with behavioral changes

Bi-directional and shared epigenomic signatures following proton and 56Fe irradiation.

The brain's response to radiation exposure is an important concern for patients undergoing cancer therapy and astronauts on long missions in deep space. We assessed whether this response is specific and prolonged and is linked to epigenetic mechanisms. We focused on the response of the hippocampus at early (2-weeks) and late (20-week) time points following whole body proton irradiation. We examined two forms of DNA methylation, cytosine methylation (5mC) and hydroxymethylation (5hmC). Impairments in object recognition, spatial memory retention, and network stability following proton irradiation were observed at the two-week time point and correlated with altered gene expression and 5hmC profiles that mapped to specific gene ontology pathways. Significant overlap was observed between DNA methylation changes at the 2 and 20-week time points demonstrating specificity and retention of changes in response to radiation. Moreover, a novel class of DNA methylation change was observed following an environmental challenge (i.e. space irradiation), characterized by both increased and decreased 5hmC levels along the entire gene body. These changes were mapped to genes encoding neuronal functions including postsynaptic gene ontology categories. Thus, the brain's response to proton irradiation is both specific and prolonged and involves novel remodeling of non-random regions of the epigenome

Postsynaptic density radiation signature following space irradiation

Introduction: The response of the brain to space radiation is an important concern for astronauts during space missions. Therefore, we assessed the response of the brain to 28Si ion irradiation (600 MeV/n), a heavy ion present in the space environment, on cognitive performance and whether the response is associated with altered DNA methylation in the hippocampus, a brain area important for cognitive performance.Methods: We determined the effects of 28Si ion irradiation on object recognition, 6-month-old mice irradiated with 28Si ions (600 MeV/n, 0.3, 0.6, and 0.9 Gy) and cognitively tested two weeks later. In addition, we determined if those effects were associated with alterations in hippocampal networks and/or hippocampal DNA methylation.Results: At 0.3 Gy, but not at 0.6 Gy or 0.9 Gy, 28Si ion irradiation impaired cognition that correlated with altered gene expression and 5 hmC profiles that mapped to specific gene ontology pathways. Comparing hippocampal DNA hydroxymethylation following proton, 56Fe ion, and 28Si ion irradiation revealed a general space radiation synaptic signature with 45 genes that are associated with profound phenotypes. The most significant categories were glutamatergic synapse and postsynaptic density.Discussion: The brain’s response to space irradiation involves novel excitatory synapse and postsynaptic remodeling

Space Radiation Alters Genotype–Phenotype Correlations in Fear Learning and Memory Tests

Behavioral and cognitive traits have a genetic component even though contributions from individual genes and genomic loci are in many cases modest. Changes in the environment can alter genotype–phenotype relationships. Space travel, which includes exposure to ionizing radiation, constitutes environmental challenges and is expected to induce not only dramatic behavioral and cognitive changes but also has the potential to induce physical DNA damage. In this study, we utilized a genetically heterogeneous mouse model, dense genotype data, and shifting environmental challenges, including ionizing radiation exposure, to explore and quantify the size and stability of the genetic component of fear learning and memory-related measures. Exposure to ionizing radiation and other external stressors altered the genotype–phenotype correlations, although different behavioral and cognitive measures were affected to different extents. Utilizing an integrative genomic approach, we identified pathways and functional ontology categories associated with these behavioral and cognitive measures

Hardware-programmable Optical Networks

Significantly regulated Kegg pathway data for the decreased RNA transcription condition for the 0.1 Gy dose are illustrated for oxidative phosphorylation. Key molecules identified included NADH dehydrogenase, Cytochrome c oxidase, and F-type ATPase. (TIFF 9302 kb

(16)Oxygen irradiation enhances cued fear memory in B6D2F1 mice.

The space radiation environment includes energetic charged particles that may impact cognitive performance. We assessed the effects of (16)O ion irradiation on cognitive performance of C57BL/6J × DBA/2J F1 (B6D2F1) mice at OHSU (Portland, OR) one month following irradiation at Brookhaven National Laboratory (BNL, Upton, NY). Hippocampus-dependent contextual fear memory and hippocampus-independent cued fear memory of B6D2F1 mice were tested. (16)O ion exposure enhanced cued fear memory. This effect showed a bell-shaped dose response curve. Cued fear memory was significantly stronger in mice irradiated with (16)O ions at a dose of 0.4 or 0.8 Gy than in sham-irradiated mice or following irradiation at 1.6 Gy. In contrast to cued fear memory, contextual fear memory was not affected following (16)O ion irradiation at the doses used in this study. These data indicate that the amygdala might be particularly susceptible to effects of (16)O ion exposure

(16)Oxygen irradiation enhances cued fear memory in B6D2F1 mice.

The space radiation environment includes energetic charged particles that may impact cognitive performance. We assessed the effects of (16)O ion irradiation on cognitive performance of C57BL/6J × DBA/2J F1 (B6D2F1) mice at OHSU (Portland, OR) one month following irradiation at Brookhaven National Laboratory (BNL, Upton, NY). Hippocampus-dependent contextual fear memory and hippocampus-independent cued fear memory of B6D2F1 mice were tested. (16)O ion exposure enhanced cued fear memory. This effect showed a bell-shaped dose response curve. Cued fear memory was significantly stronger in mice irradiated with (16)O ions at a dose of 0.4 or 0.8 Gy than in sham-irradiated mice or following irradiation at 1.6 Gy. In contrast to cued fear memory, contextual fear memory was not affected following (16)O ion irradiation at the doses used in this study. These data indicate that the amygdala might be particularly susceptible to effects of (16)O ion exposure

Genetic counseling following direct‐to consumer genetic testing: Consumer perspectives

As the use and scope of direct‐to‐consumer genetic testing (DTC GT), also becoming known as consumer‐driven genetic testing, increases, consumers may seek genetic counseling to understand their results and determine healthcare implications. In this study, we interviewed individuals who sought genetic counseling after receiving DTC GT results to explore their motivations, expectations, and experiences. Participants were recruited from the Impact of Personal Genomics (PGen) Study, a longitudinal cohort study of DTC GT customers. We interviewed 15 participants (9 females, mean age = 38 years) by telephone and analyzed the double‐coded transcripts using qualitative methods. Motivations for genetic counseling included family and personal health histories, concern and confusion about results, and information‐seeking; of note, one‐third of our interview participants had Ehlers‐Danlos syndrome Type III (hypermobility type). Expectations of genetic counseling sessions were high. Participants generally saw DTC GT results as valid and potentially impactful for their healthcare, wanted more thorough explanations in “layman’s terms,” a pooling of their results with their family and personal health history and a “game plan.” Several participants had already accessed online resources, including resources typically used by genetics clinicians. Our results point to several elements of a successful DTC GT genetic counseling session: 1) effective contracting when starting the clinic visit, especially determining motivations for genetic counseling, results that are concerning/confusing and resources already accessed; 2) ascertainment and management of expectations and clearly communicating if and why all results may not be reviewed; 3) explaining how DTC GT differs from clinical genetic testing and why additional testing may not be indicated and 4) listening to (not dismissing) patient concerns about their results. For those patients who seek genetic counseling about DTC GT results, the findings from our study can help inform case preparation and provision of genetic counseling.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/166358/1/jgc41309_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/166358/2/jgc41309.pd

The Propensity to Government Budget Deficit: Analysis of the Influence of Political Cycle on Czech Fiscal policy

The basic goal of diploma thesis "The Propensity to Government Budget Deficit: Analysis of the Influence of Political Cycle on Czech Fiscal policy" is to identify fundamental factors which influence decisions about the size of government budget balance and to analyze the influence of political cycle on the volume and structure of government expenditures in the period of 1993-2009. Analysis is based on theories which are connected to the areas of public sector, state and its function, public finances, government budget, the process of generating budget, political cycle, political parties and europeanization. The problem of propensity to budget deficits is structured using dimensional analysis and problem tree. The influence of political cycle is verified by using the combination of qualitative analysis of policy documents and quantitative analysis of specific indicators. Analysis classifies external and internal factors influencing the tendency to deficit budgeting. Political cycle is one of those internal factors becouse it is affected by the decision making process of political representatives. The influence of political cycle on the volume of government expenditures and the expenditures of the Ministry of Labor and social affairs could not be demonstrated on data. Otherwise, there is possibility..