Astronauts on a mission to Mars would be exposed for up to 3 years to galactic cosmic rays (GCR) — made up of high-energy protons and high charge (Z) and energy (E) (HZE) nuclei. GCR exposure rate increases about three times as spacecraft venture out of Earth orbit into deep space where protection of the Earth's magnetosphere and solid body are lost. NASA's radiation standard limits astronaut exposures to a 3% risk of exposure induced death (REID) at the upper 95% confidence interval (CI) of the risk estimate. Fatal cancer risk has been considered the dominant risk for GCR, however recent epidemiological analysis of radiation risks for circulatory diseases allow for predictions of REID for circulatory diseases to be included with cancer risk predictions for space missions. Using NASA's models of risks and uncertainties, we predicted that central estimates for radiation induced mortality and morbidity could exceed 5% and 10% with upper 95% CI near 10% and 20%, respectively for a Mars mission. Additional risks to the central nervous system (CNS) and qualitative differences in the biological effects of GCR compared to terrestrial radiation may significantly increase these estimates, and will require new knowledge to evaluate.

The mammalian RON and the avian sea genes encode tyrosine kinase receptors of poorly characterized biological functions. We recently identified macrophage-stimulating protein as the ligand for Ron; no ligand has yet been found for Sea. In this work we investigated the biological response to macrophage-stimulating protein in mouse liver progenitor cells expressing Ron. These cells were also transfected with a chimeric cDNA encoding the cytoplasmic domain of Sea, fused to the extracellular domain of Trk (nerve growth factor receptor). In the presence of nanomolar concentrations of the respective ligands, both receptors induced cell "scattering", extracellular matrix invasion, and DNA synthesis. When liver progenitor cells were grown in a tri-dimensional type-I collagen matrix, ligand-induced stimulation of either Ron or Sea induced sprouting of branched cell cords, evolving into ductular-like tubules. The motogenic, mitogenic, and morphogenic responses were also elicited by triggering the structurally related hepatocyte growth factor receptor (Met) but not epidermal growth factor or platelet-derived growth factor receptors. These data show that Ron, Sea, and Met belong to a receptor subfamily that elicits a distinctive biological response in epithelial cells.

NASA’s plans for space exploration include a return to the Moon to stay—boots back on the lunar surface with an orbital outpost. This station will be a launch point for voyages to destinations further away in our solar system, including journeys to the red planet Mars. To ensure success of these missions, health and performance risks associated with the unique hazards of spaceflight must be adequately controlled. These hazards—space radiation, altered gravity fields, isolation and confinement, closed environments, and distance from Earth—are linked with over 30 human health risks as documented by NASA’s Human Research Program. The programmatic goal is to develop the tools and technologies to adequately mitigate, control, or accept these risks. The risks ranked as “red” have the highest priority based on both the likelihood of occurrence and the severity of their impact on human health, performance in mission, and long-term quality of life. These include: (1) space radiation health effects of cancer, cardiovascular disease, and cognitive decrements (2) Spaceflight-Associated Neuro-ocular Syndrome (3) behavioral health and performance decrements, and (4) inadequate food and nutrition. Evaluation of the hazards and risks in terms of the space exposome—the total sum of spaceflight and lifetime exposures and how they relate to genetics and determine the whole-body outcome—will provide a comprehensive picture of risk profiles for individual astronauts. In this review, we provide a primer on these “red” risks for the research community. The aim is to inform the development of studies and projects with high potential for generating both new knowledge and technologies to assist with mitigating multisystem risks to crew health during exploratory missions.

The use of microarrays for parallel screening of nucleic acid profiles has become an industry standard. Similar efforts for screening protein-protein interactions are gaining momentum, however, they remain limited by the requirement for relatively large sample volumes. One strategy for overcoming this problem is to significantly decrease the size and consequently the sample volume of the protein interaction assay. We report here on our progress over the last two years in the construction of ultraminiaturized, functional protein capture assays. Each one micron spot in these array-based assays covers less than 1/1000(th) of the surface area of a conventional microarray spot while still maintaining enough antibodies to provide a useful dynamic range. These nanoarray assays can be read by conventional optical fluorescence microscopy as well as by novel label-free methods such as atomic force microscopy. The size reduction realized by functional protein nanoarrays also creates opportunities for novel applications including highly multiplexed single cell analysis and integration with microfluidics and other "lab-on-a-chip" technologies.

Most accelerator-based space radiation experiments have been performed with single ion beams at fixed energies. However, the space radiation environment consists of a wide variety of ion species with a continuous range of energies. Due to recent developments in beam switching technology implemented at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), it is now possible to rapidly switch ion species and energies, allowing for the possibility to more realistically simulate the actual radiation environment found in space. The present paper discusses a variety of issues related to implementation of galactic cosmic ray (GCR) simulation at NSRL, especially for experiments in radiobiology. Advantages and disadvantages of different approaches to developing a GCR simulator are presented. In addition, issues common to both GCR simulation and single beam experiments are compared to issues unique to GCR simulation studies. A set of conclusions is presented as well as a discussion of the technical implementation of GCR simulation.

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Novel quill-type cantilever-based surface patterning tools (SPTs) were designed and constructed for use in controlled placement of femtoliter volumes of biological molecules on surfaces for biological applications. These tools were fabricated from silicon dioxide using microelectromechanical systems (MEMS) techniques. They featured a 1 microm split gap, fluidic transport microchannels and self-replenishing reservoirs. Experimental trials were performed using these tools on NanoArrayer molecular deposition instrumentation. Cy3-streptavidin was loaded as a biological sample and patterned on an amine-reactive dithiobis-succinimidyl undecanoate (DSU) monolayer on gold. Results showed these tools were capable of generating high quality biological arrays with routine spot sizes of 2-3 microm. The spot size could potentially achieve sub-micron dimensions if these SPT designs are reduced in size by more precise microfabrication techniques. The geometric designs of these tools facilitated sample replenishment from the local reservoir on the cantilever which allowed printing of large numbers of spots without sample reloading.

c-sea is the cellular homologue of the avian erythroblastosis virus S13-encoded oncogene v-sea. We have isolated and determined the nucleotide sequence of overlapping chicken cDNAs that encode the putative c-sea protooncogene product. The predicted reading frame encoded a 1404-aa polypeptide that had the structure of a receptor-like proteintyrosine kinase and exhibited the highest degree of sequence similarity with the Met/hepatocyte growth factor/scatter factor receptor. Analysis of steady-state RNA expression revealed that c-sea mRNA levels were elevated ==5-fold in chicken embryo cells transformed by activated variants of the src nonreceptor protein-tyrosine kinase gene but not in cells transformed by the nuclear oncogenes v-myc or v-rel. A survey of c-sea expression in a variety ofchicken tissues indicated that the hihest levels of mRNA were located in peripheral white blood cell populations and in the intestine.The avian erythroblastosis virus S13 is an oncogenic retrovirus that transforms both chicken and quail embryo fibroblasts and chicken erythroid cultures in vitro (1, 2). The oncogenic potential of the S13 virus results from the acquisition of cellular DNA sequences encoding a tyrosine kinase termed sea (for sarcoma, erythroblastosis, and anemia) (3). The transforming oncogene of S13 (v-sea) encodes a 155-kDa transmembrane glycoprotein that contains extracellular and transmembrane regions derived from the viral envelope gene and a sea-derived intracellular domain possessing tyrosinespecific protein-kinase activity (4). The v-sea-encoded protein shares amino acid homology with the kinase domain of the Met protein, a receptor tyrosine kinase (5).The cellular met locus encodes a receptor protein-tyrosine kinase with a distinctive heterodimeric structure (6-8). The protein is synthesized as a 190-kDa precursor that is proteolytically processed into an amino-terminal 50-kDa a chain and a carboxyl-terminal 145-kDa P chain. Recently, Met was identified as the receptor for hepatocyte growth factor (HGF) and scatter factor (SF), two identical proteins with distinct biological activities (9,10).In this report we describe the cloning and characterization of cDNAs encoding the cellular homologue of the sea oncogene, c-seaA c-sea was found to encode a receptor tyrosine kinase that exhibited structural similarity to Met in both the extracellular ligand-binding domain and the cytoplasmic tyrosine kinase domain. c-sea exhibited a highly restricted pattern of expression in cells and tissues. The highest levels of c-sea expression were observed in peripheral white blood cell populations, whereas most tissues (muscle, liver, heart, brain, kidney, spleen, and thymus) contained low or undetectable levels ofc-sea RNA. We also show that c-sea mRNA levels were significantly elevated in chicken embryo (CE)