Gene Expression as a Dosimeter in Irradiated Drosophila melanogaster

Biological indicators would be of use in radiation dosimetry in situations where an exposed person is not wearing a dosimeter, or when physical dosimeters are insufficient to estimate the risk caused by the radiation exposure. In this work, we investigate the use of gene expression as a dosimeter. Gene expression analysis was done on 15,222 genes of Drosophila melanogaster (fruit flies) at days 2, 10, and 20 postirradiation, with X-ray exposures of 10, 1000, 5000, 10,000, and 20,000 roentgens. Several genes were identified, which could serve as a biodosimeter in an irradiated D. melanogaster model. Many of these genes have human homologues. Six genes showed a linear response (R2 \u3e 0.9) with dose at all time points. One of these genes, inverted repeat-binding protein, is a known DNA repair gene and has a human homologue (XRCC6). The lowest dose, 10 roentgen, is very low for fruit flies. If the lowest dose is excluded, 13 genes showed a linear response with dose at all time points. This includes 5 of 6 genes that were linear with all radiation doses included. Of these 13 genes, 4 have human homologues and 8 have known functions. The expression of this panel of genes, particularly those with human homologues, could potentially be used as the biological indicator of radiation exposure in dosimetry applications

Evaluation of the Activity of Zn-65 Isotope and Radiation Dose Delivered to Drosophila melanogaster

Radioactivity is a natural part of our environment. Ionizing radiation from radioactive materials can affect the life cycle of organisms; sometimes increase the rate of transition between cycle leading to the proliferation of cells as seen in some cancer cells or delay the rate of transition between cell cycle. A NaI detector is essential to determine the activity of a radioactive material. To determine the resolution of NaI detector and the efficiency of the geometry used for this experiment, quality control was done for NaI detector using 22Na reference source. The efficiency of the detector was used to verify the activity of 65Zn sample source which was used to irradiate Drosophila melanogaster. The dose rate at points close to 65Zn was calculated and also measured using thermoluminescent dosimeters. The cumulative average dose over the tubes containing fruit flies was also evaluated. It was discovered that both the resolution and efficiency of the detector decreases with the increase in photon energy. The detector resolution was found to be 13 ± 1 % at 511 keV, and 6.92 ± 0.04 at 1275 keV. At 511 keV the efficiency was 0.02 and at 1275 keV, the efficiency was 0.00712. The calculated and experimental values of 65Zn activity were 38.33 MBq and 37.36 MBq respectively, with 2.5 % difference. At 2 cm and 10 cm away from 65Zn, the measured and calculated dose rates were very close with 3.7 % and 1.8 % differences. The percentage difference in the dose rates from online radprocalculator and experimental values at 2 cm and 10 cm were 35 % and 26.6 % respectively. The average dose to all generations of fruit flies was 160 ±10 rad. The activity of 65Zn calculated using the detector’s efficiency value was very close to the value calculated using the manufacturer’s value. The online radprocalculator should be reviewed to accommodate for X-rays from the radioactive samples for points close to the sample. An investigation into the gene expression and inquiries into physical and behavioral changes, life span, and resistance to stress of the offspring of the irradiated flies should be done

Survival of white blood cells of mice (mus muscullus l) against adaptation dose of gamma co-60 radiation

Several studies on the effects of low dose radiation have shown a shift in the three main paradigms of radiation biology. One of them is a phenomenon known as adaptation response. The phenomenon of adaptation response is a response that occurs when changes in gene expression can be induced by exposure to low doses of radiation around <0.5Gy. Changes in gene expression in certain circumstances serve to protect cells against the effects of subsequent radiation exposure with higher doses (dose challenges). The purpose of this study was to obtain a radiotherapy method that could show a reduction in patient dosage. In this study, the sample of mice (mus muscullus l) was divided into 6 groups, namely 1 control group and 5 treatment groups. Five treatment groups were given an adaptation dose of 0.05Gy for treatment I; 0.10Gy treatment II, 0.15Gy treatment III, 0.2 Gy treatment IV, and treatment V; 0.25Gy. Furthermore, all treatments were immediately given a challenge dose 3Gy. The results of the analysis showed that the lowest leukocyte cell survival occurred on day 30 and returned to normal conditions on day 60 after gamma Co-60 radiation

Apoptosis and immune system adaptation in Drosophila melanogaster following space flight and irradiation

Das Leben auf der International Raumstation ISS birgt ständige neue Herausforderung für Astronauten, Wissenschaftler und Techniker. Die Schwerelosigkeit führt bei längeren Aufenthalten im All unter anderem zu Muskelschwund, Knochenabbau und Veränderungen des Flüssigkeitshaushaltes. Das erhöhte Strahlungsniveau in der Erdumlaufbahn und auf interplanetaren Reisen kann zu Krebs und anderen Krankheiten führen, da hier das magnetische Feld der Erde nicht mehr schützend wirkt. Das NASA FIT Projekt – Fungal Pathogenesis, Immunity and Tumorigenesis Studies – bestand aus einem 12-tägigen Space Shuttle Flug mit Drosophila melanogaster Fruchtfliegen, als auch aus Bestrahlungsstudien mit Protonen, um die Auswirkungen dieser Effekte auf zellulärer und genetischer Ebene zu charakterisieren. Das Ziel dieser Arbeit, als Teil des FIT Projekts, war die Beschreibung der Apoptose und Immunsystem Veränderungen nach einem Raumflug beziehungsweise nach Protonenbestrahlung auf der Erde. Es ist bekannt, dass diese zwei zellulären Systeme eng miteinander arbeiten, weshalb Veränderungen durch Weltraumbedingungen durchaus Auswirkungen auf beide Systeme haben können. RT-PCR Genexpressions Studien von Minibrain, Morgue und Wengen, drei Proteine, die sowohl bei Zelltod als auch im Immunsystem wichtige Rollen spielen, zeigten einen ersten Trend zu erhöhter Apoptose Aktivität bei bakteriell infizierten, Space Shuttle geflogen Fliegen im Vergleich zu infizierten Bodenkontrolltieren. Diese Trends wurden auch durch erhöhte Caspase Enzym Aktivität bei den geflogen Tieren bestätigt. Protonen Bestrahlung zeigt einen Anstieg der DNA Fragmentierung, veranschaulicht durch den TUNEL Assay. Weiters wurde gezeigt, dass der Tumor Suppressor p53 in Folge von selbiger Bestrahlung erhöhte Expression zeigt. Phagocytose Aktivität wurde mittels des Alexa Fluor E.coli Phocytose Assays und des Clearance Assays ermittlet, welche beide einen Anstieg der Hemocyten Aktivität als Folge der Bestrahlung.Living and working in space produces new challenges to astronauts, engineers and scientists due to several unique properties of this environment. For instance, weightlessness or microgravity is responsible for reduced exercise of skeletal muscles resulting in muscle atrophy as well as osteoporosis-like bone loss. Away from the Earth’s protective magnetic field, space radiation can damage nucleic acids, cells and tissues resulting in radiation sickness or cancer. The NASA FIT project – Fungal Pathogenesis, Immunity and Tumorigenesis Studies – involved a 12-day Space Shuttle experiment with Drosophila melanogaster flies. Additionally, ground based studies involved the exposure of flies to proton irradiation to investigate the genetic, cellular and behavioural effects. The aims of this project, as part of FIT, were to characterize adaptations of apoptosis and immune system functions following space flight as well as ground based proton radiation exposure. Furthermore, it was of interest if changes in immune system function can be linked to an altered level of apoptosis. RT-PCR gene expression studies of Minibrain, Morgue and Wengen, proteins involved in cell death and immune system functions, showed a trend towards increased apoptotic activity of space flown flies after a bacterial infection in comparison to infected ground control flies. Those trends were also observed by measurement of caspase enzyme activities in space flown animals. Proton irradiation increased fragmentation of DNA in Drosophila hemocytes, which was investigated with the TUNEL assay. Tumor suppressor p53 activation in response to proton treatment was shown with a Drosophila strain containing a p53 radiation response element in front of a GFP protein. Phagocytosis activity was investigated with the Alexa Fluor E.coli Phagocytosis Assay and the Clearance Assay, both showing that high proton irradiation exposure levels can be responsible for an elevated activity level in hemocytes

Preliminary Development of a Biological Dosimeter

Sanitary and Public Health Engineerin

Developing a workflow for the multi-omics analysis of Daphnia

In the era of multi-omics, making reasonable statistical inferences through data integration is challenged by data heterogeneity, dimensionality constraints, and data harmonization. The biological system is presumed to function as a network where the physical relationships between genes (nodes) are represented by links (edges) connecting genes that interact. This thesis aims to develop a new and efficient workflow to analyse non-model organism multi-omics data for researchers who are entangled in the biology questions by using readily available software tools. The proposed approach was applied to the transcriptome and metabolome data of Daphnia magna under various dose rates of gamma radiation. The first part of this workflow compares and contrasts the transcriptional regulation of short-and long-term gamma radiation exposure. A group of genes which share a similar expression across different samples under the same conditions are known as modules, because they are likely to be functionally relevant. Modules were identified using WGCNA but biologically meaningful modules (significant modules) were selected through a novel approach that associates genes with significantly altered expression levels as a result of radiation (i.e. differentially expressed genes) with these candidate modules. Dynamic transcriptional regulation was modelled using transcription factor (TF) DNA binding patterns to associate TFs with expression responses captured by the modules. The biological functions of significant modules and their TF regulators were verified with functional annotations and mapped into the proposed Adverse Outcome Pathways (AOP) of D. magna, which describes the key events which contribute to fecundity reduction. The findings demonstrate that short term radiation impacts are entirely different from long term and cannot be used for long term prediction. The second part investigates the coordination of gene expression and metabolites with differential abundances induced by different gamma dose rates and the underlying mechanisms contributing to the varying extent of the reduction in fecundity. Significant modules which belong to the same design model of dose rates were combined and annotated with new functionality. The abundance of metabolites was also modelled with the same design model. Integrated pathway enrichment analysis was performed to discover and create pathway diagrams for visualising the multi-omics output. Finally, the performance of this workflow on explaining the reduction of fecundity of D. magna, which has not been described in previous studies, has been evaluated. Combining the information from the metabolome and transcriptome data, new insights suggest that the alteration to the cell cycle is the underlying mechanism contributing to the varying reduction of fecundity under the effect of different dose rates of radiation.M-G

Analyzing “Hot Spots” Created by Electron Beam (eBeam) Technology

Electron beam (eBeam) technology is commonly used to sterilize food and food ingredients to inactivate microbial pathogens. In eBeam processing, electrons are accelerated to the speed of light in a linear accelerator, before being showered over a product, resulting in microbial inactivation. It causes multiple single and double strand breaks in the DNA of microbial pathogens and other organisms that may be present. If the cell undergoes numerous double-strand DNA breaks, the bacterium is considered inactivated because it can no longer multiply. When exposed to electron beam (eBeam) irradiation it has been observed that bacterial genomE undergoes fragmentation. However, it is unclear whether there are “hot spots” in the genome for these DNA breakages. It is important to understand whether “hotspots” exist that help create these breakages when DNA encounters electrons. These studies can lead to a better understanding of the effects eBeam has on bacterial DNA. This will also help to determine how bacterial cells respond to eBeam irradiation. E. coli and Salmonella cells were exposed to a kill dose of eBeam irradiation to measure differences in physical damage. The experimental objective was to determine whether eBeam creates random DNA breakages or if there are “hot spots” where the double stranded DNA breaks occur