Project description:We report whole transcriptome sequencing of the intraventricular septum of mouse heart 2 and 6 weeks after 25 Gy ionizing radiation. The objective of this experiment was to identify genes and pathways differentially regulated by ionizing radiation in the heart. Image-guided isocentric gamma irradiation was delivered to experimental groups under isoflurane anesthesia in a single, 25 Gy dose over approximately 15 minutes. Control group animals were experimental group littermates which received anesthesia and CT imaging but no radiation. RNA was isolated from intraventricular septum using TRIzol.
Project description:We sought to determine the long-term effects of radiation (IR) on gene expression in the whole heart as a function of IR type and dose. We hypothesize that compared to low doses of gamma-IR, high charge and energy (HZE) particle-IR may have different biological response thresholds in cardiac tissue at lower doses, and these effects may be IR type- and dose-dependent. We provide for the first time the transcriptome analysis of mouse hearts exposed to low and very low doses of gamma- (137Cs), silicon- (14Si), and titanium- (22Ti) irradiation. Our results show that 16 months after low and very low dose IR exposure, the gene expression in the heart tissue is significantly differentially regulated, suggesting there are long-term effects on dysregulation of varying molecular pathways that are associ-ated with various degrees of cardiovascular, pulmonary and metabolic diseases, as well as biological processes, including abnormal circadian rhythm, cancer, Hutchinson-Gilford progeria syndrome, etc.
Project description:We are investigating the response of human lymphoblastoid cells to low-dose exposure of environmental metals We used microarrays to detail the global programme of gene expression upon response to low-dose metals Keywords: dose
Project description:Expression profiles in mouse liver exposed to long-term gamma-irradiation were examined to assess in vivo effects of low dose-rate radiation. Three groups of male C57BL/6J mice were exposed to whole body irradiation at dose-rates of 17-20 mGy/day, 0.86-1.0 mGy/day or 0.042-0.050 mGy/day for 401-485 days (cumulative doses were approximately 8 Gy, 0.4 Gy or 0.02 Gy, respectively). Expression profiles were produced for RNA isolated from irradiated individual animals and for pooled RNA from sham-irradiated 3 animals for control. The expression levels of 6 irradiated animals for each dose were compared individually with those of 2 pooled controls (3 irradiated samples to one pooled control in first and second experiments).
Project description:The immune system illustrates the challenges of assigning risk to low dose radiation (LDR) exposure in a population. While high radiation doses clearly suppress immune function, a number of studies have shown that LDR affects immune cell subpopulations in ways that could be beneficial. In the intact organism, defining the consequences of LDR is further complicated by the impact of genetic background, particularly in systems such as the immune system for which both radiosensitivity and genetic effects are profound. We employed a systems genetics approach to test for heritable differences in LDR responses. Mice from 39 BXD recombinant inbred (RI) strains were exposed to 10cGy gamma radiation to determine effects on immune function and oxidative stress 48h after irradiation. LDR significantly enhanced neutrophil phagocytosis in a manner that was independent of genetic background. In contrast, genetic background significantly impacted LDR-induced changes in spleen superoxide dismutase activity. Transcriptome data from spleens of the BXD parental strains highlighted the impact of genetic background on LDR responses and also indicate that genetic variation in radiosensitivity is further unmasked at low radiation doses. Taken together, these data highlight the need to consider genetic variation when assessing LDR outcomes. Adult C57BL/6J and DBA/2J mice (10 weeks old) were exposed to low dose (10cGy) or high dose (1Gy) gamma radiation. Mice were sacrificed 24h after radiation or sham exposure & spleens were harvested for transcriptomic analysis.
Project description:Characterization of biological and chemical responses to ionizing radiation by various organisms is essential for potential applications in bioremediation, alternative modes of detecting nuclear material, and national security. Escherichia coli DH10β is an optimal system to study the microbial response to low-dose ionizing radiation at the transcriptional level because it is a well-characterized model bacterium and its responses to other environmental stressors, including those to higher radiation doses, have been elucidated in prior studies. In this study, RNA sequencing with downstream transcriptomic analysis (RNA-seq) was employed to characterize the global transcriptional response of stationary-phase E. coli subjected to Pu-239, H-3 (tritium), and Fe-55, at an approximate absorbed dose rate of 10 mGy day-1 for 1 day and 15 days. Differential expression analysis identified significant changes in gene expression of E. coli for both short- and long-term exposures. Radionuclide source exposure induced differential expression in E. coli of genes involved in biosynthesis pathways of nuclear envelope components, amino acids, and siderophores, transport systems such as ABC transporters and type II secretion proteins, and initiation of stress response and regulatory systems of temperature stress, the RpoS regulon, and oxidative stress. These findings provide a basic understanding of the relationship between low-dose exposure and biological effect of a model bacterium that is critical for applications in alternative nuclear material detection and bioremediation. IMPORTANCE Escherichia coli strain DH10β, a well-characterized model bacterium, was subjected to short-term (1-day) and long-term (15-day) exposures to three different in situ radiation sources comprised of radionuclides relevant to nuclear activities to induce a measurable and identifiable genetic response. We found E. coli had both common and unique responses to the three exposures studied, suggesting both dose rate- and radionuclide-specific effects. This study is the first to provide insights into the transcriptional response of a microorganism in short- and long-term exposure to continuous low-dose ionizing radiation with multiple in situ radionuclide sources and the first to examine microbial transcriptional response in stationary phase. Moreover, this work provides a basis for the development of biosensors and informing more robust dose-response relationships to support ecological risk assessment.
Project description:Influenza A virus (IAV) infection leads to severe inflammation, and while epithelial-driven inflammatory responses occur via activation of NF-B, the factors that modulate inflammation, particularly the negative regulators are less well-defined. In this study we show that A20 is a crucial molecular switch that dampens IAV-induced inflammatory responses. Chronic exposure to low-dose LPS environment can restrict this excessive inflammation. The mechanisms that this environment provides to suppress inflammation remain elusive. Here, our evidences show that chronic exposure to low-dose LPS suppressed inflammation in A549 cells induced by IAV infection or LPS stimulationn. Chronic low-dose LPS environment increases A20 expression, which in turn positively regulates PPAR-α and -γ, thus dampens the NF-κB signaling pathway and NLRP3 inflammasome activation. Knockout of A20 abolished the inhibitory effect on inflammation. Thus, A20 and its induced PPAR-α and -γ play a key role in suppressing excessive inflammatory responses in the chronic low-dose LPS environment.