[en] In human reproduction, the first two weeks of pregnancy cannot be detected by existing hormonal tests. Therefore, irradiation for medical purposes during this period poses a risk of damaging DNA within the cells of the newly formed embryo and could lead to malformations. p53 is a protein playing a pivotal role in DNA repair, aging and apoptosis (or programmed cell death). In our laboratory, we have previously shown the importance of this protein for normal embryonic development. Indeed, mouse foetuses deficient for the p53 protein were more prompted at developing malformations (exencephaly, gastroschisis, polydactyly, cleft palate) if they were irradiated at day 8 post conception. The chromosome ends (also called telomeres) are known to be causal determinants for biological aging but are also involved in embryonic development. Since only little information is available on telomere biology early in development, we are interested in studying the telomere biology in normal and abnormal mouse foetuses within each p53 genotype (+/+, +/- and -/-). Our ultimate goal is to find some reliable biological markers (telomeres, proteins, gene modulation, ...) that could help in understanding the molecular pathways underlying radiation-induced malformations. In this perspective, we first addressed the question of telomere length changes in the normal versus abnormal X-irradiated foetuses. Principal results are presented

[en] With a mission to Mars and a permanent base on the moon as the ultimate dream, space travel is continually pushing back the frontiers. But long space missions present great challenges for science, for example in the field of microbiology. Together with the European Space Agency (ESA), SCK-CEN is studying the effects of space travel conditions on the behaviour of bacteria. In 2009 the SCK-CEN experts completed four innovative research projects at the cutting edge of microbiology, radiation sciences and space travel.

[en] One of the main objectives of current microbiological research at SCK-CEN is to develop fast and reproducible ways of estimating physiological status of bacteria. Therefore, methodologies have been elaborated in order to monitor a wide variety of fine physiological changes under stress in bacteria, namely fine changes in bacterial size, shape, viability, membrane properties, enzymatic activity, intracellular pH, calcium concentration, DNA/RNA ratio as well as the response to oxidative stress. The article describes the main achievements in 2003

[en] Exposure of cells to ionising radiation induces DNA damage. Cells have the ability to sense DNA damage, and to activate repair pathways that efficiently remove such damage and restore the integrity of the DNA. Highly sophisticated mechanisms further enable cells to actively stall growth and division after sensing DNA damage or alternatively to induce programmed cell death (apoptosis). Research performed at SCK-CEN has the goal to expanding the knowledge of the cellular and molecular mechanisms that determine sensitivity or resistance to ionising radiation of normal (adult and embryonic) and cancerous cells. In particular, the physiological effects induced by ionising radiation are studied in the light of the biochemistry of the p.53 protein that is an integrator of stress signals from various damaging exposures and that fulfills the function of genome guardian by regulating checkpoints of the cell cycle, DNA reparation and apoptosis

[en] The topical day has been focussed on the potential effects of ionizing radiation on human health. A general overview on molecular and biophysical aspects of radiation, its effects on cells and organisms, and the contribution of radiobiology to radiation protection and risk assessment is given. The genetic effects of radiation and its effects on the developing organism, the effects of radiation on the cell cycle and the mechanisms of radiation induced apoptosis were also discussed

[en] Prolonged exposure to space radiation and extended microgravity has revealed profound physiological and clinical changes in astronauts. The health problems thought to be related to the effects of microgravity include a decrease in the heart and the respiratory rates, a loss of body weight, changes in bone calcium, a redistribution of body fluids with a greater amount in the upper body, a decrease in muscle tissue, a weakening of the veins and arteries in the legs, as well as an underproduction of red blood cells leading to anaemia. At the cellular and molecular levels, microgravity is known to induce both a loss of T-cell activation and changes in gene expression patterns, as well as a three-dimensional growth of normal cells and tumour cells, an alteration of the mitochondrial organization, a modification of the production of extracellular matrix proteins and apoptosis in some types of cells. The Earth's magnetic field protects us from harmful radiation. On Earth, we are still exposed to small amounts of radiation when we go for medical x-rays, when we travel on transcontinental flights or just from radon in the air. However, astronauts are exposed to 50 to 100 times as much radiation - and that is just in a low Earth orbit. In deep space, astronauts can be exposed to even higher doses. It is well known that large amounts of radiation can cause severe health effects by altering DNA in our cells. The health effects from space radiation are therefore a critical safety concern for long-term space travel. Possible health risks include cancer, cataracts, acute radiation sickness, hereditary effects, and damage to the central nervous system. The aims of this research are 1) to ensure the immunological monitoring of a cohort of astronauts (having spent around 6 months aboard the International Space Station ISS) and 2) to investigate the effects of an in vitro exposure of endothelial cells and other types of cells to radiation and/or microgravity conditions

[en] Radiotherapy, radiation protection, nuclear medicine, etc.: there is a growing interest in radio(bio)logy in the health care sector. The number of medical treatments with ionising radiation per year will increase even more. It is therefore increasingly important to closely monitor the possible harmful effects of low radiation doses.

[en] One-cell embryos of the BALB/c strain are extremely sensitive to the radiation-induced G2-arrest. Earlier studies suggested that the period of sensitivity to this effect is restricted to the S phase. This point was now studied more in details, using very synchronous embryonic populations and a higher dose of X-rays. The sensitivity towards radiation-induced G2-arrest was also investigated at the two immediately following stages of preimplantation development, i.e. the two-cell and the four-cell stages. (authors)

[en] Although radiations are known to produce mutations, there is a paucity of information on the production of germ-line mutations leading to heritable anomalies. Information obtained from studies on phenotypic anomalies is valuable to assess the genetic risk of radiation in man because it shows a similar irregular and uncertain inheritance and most of the induced anomalies are like those found in humans. Early prenatal mortality appears as the greatest risk associated with an exposure of the immature oocytes to radiation. In conclusion, our results do not support a particular sensitivity of the immature oocyte to the mutagenic effect of irradiation. They therefore rather invalidate the hypothesis of Nomura where the immature oocyte was found more sensitive than the mature oocyte for the induction of congenital anomalies in the offspring of irradiated females. (authors)

No abstract available