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We are investigating a role for proton radiation-induced changes in FGF-2 gene expression as part of the mechanism(s) underlying lens cell injury. Radiation injury to the human lens is associated with the induction of cataract following exposure to protons.
Our studies use a series of syngeneic, and where possible, isogenic human B-lymphoblastoid cell lines to assess the genetic factors that modulate susceptibility apoptosis and their impact on the mutagenic risks of low fluence exposures to 1 GeV Fe ions and 55 MeV protons. These ions are representative of the types of charged particle radiation that are of particular significance for human health in the space radiation environment. The model system employs cell lines derived from the male donor WIL-2. These cells have a single X chromosome and they are hemizygous for one mutation marker, hypoxanthine phosphoribosyltransferase (HPRT). TK6 and WTK1 cells were each derived from descendants of WIL-2 and were each selected as heterozygotes for a second mutation marker, the thymidine kinase (TK) gene located on chromosome 17q. The HPRT and TK loci can detect many different types of mutations, from single basepair substitutions up to large scale loss of heterozygosity (LOH). The single expressing copy of TK in the TK6 and WTKI cell lines is found on the same copy of chromosome 17, and this allele can be identified by a restriction fragment length polymorphism (RFLP) identified when high molecular weight DNA is digested by the SacI restriction endonuclease and hybridized against the cDNA probe for TK. A large series of polymorphic linked markers has been identified that span more than 60 cM of DNA (approx. 60 megabasepairs) and distinguish the copy of chromosome 17 bearing the initially active TK allele from the copy of chromosome 17 bearing the silent TK allele in both TK6 and WTKI cells. TK6 cells express normal p53 protein while WTKI cells express homozygous mutant p53. Expression of mutant p53 can increase susceptibility to x-ray-induced mutations. It's been suggested that the increased mutagenesis in p53 mutant cells might be due to reduced apoptosis.
Our previous studies have demonstrated that 2G exposure via centrifugation significantly attenuated the daily mean and circadian rhythm amplitude of rat body temperature (Tb), heart rate, and activity (Act). In addition, 2G exposure activates neural responses in several vestibular, autonomic, and circadian nuclei. Although we have characterized the effect of 2G on an animal's physiological, neuronal, and behavioral responses, it will be important to understand the underlying neural and physiological mechanisms that mediate those responses. For example, the vestibular responses, proprioceptive feedback, or fluid shifts may be the critical factors that mediate the responses to 2G. As a first step to understand the relative importance of these different response pathways to altered gravitational fields, this study examined the contribution of the vestibular system by utilizing an animal model from molecular biology. Brain 3.1 (Bm 3.1) is a POU domain homeobox gene involved in the normal development of the vestibular and auditory system. Brn 3.1 deletion results in a loss of hair cells in the otoliths, semicircular canals, and cochlea. As a result mice with a Brn 3.1 deletion do not have a functioning vestibular or auditory system. The BRN 3.1 knockout mouse could be a very useful animal model for isolating the role of the vestibular system in mediating the physiological responses to 2G exposure. Therefore, this study compared the effect of 2G exposure via centrifugation between Brn 3.1 knockout (KO) versus Wildtype (W) mice.
This document represents a report on a meeting about Archaea. The meeting had an unusually diversified mix of topics all related to Archaea highlighting their differences and similarities with other kingdoms of life. Thus, a large number of scientists from others areas of biology participated in this conference. One-third of the speakers (11 of 33) represented laboratories whose main interests have not been archaea and who have not previously participated in similar symposia or workshops. Thus, this symposium provided a unique opportunity for archaeal researchers to interact in a wider forum. Because of the broad range of topics covered, the conference also introduced many of the participants to new areas of archaeal research. The discussions of genomics, molecular mechanisms of transcription, metabolic pathways and evolution were at a very high level. Talks and posters provided detailed discussions of the state of the current knowledge in RNA processing, transcriptional initiation, chromatin structure, aminoacyl-tRNA synthetases, autotrophic CO2 fixation, Upid biosynthesis and a wide range of other topics. In addition to providing overviews, major areas of scientific argument were clearly delineated, particularly in the discussions of genomics and evolution. Some of the questions raised included: how representative are individual gene trees of organismal evolution, how prevalent is horizontal evolution, how reliable are functional assignments in genomics? On these topics, the different points of view were well represented. The future of any field depends on the enthusiasm and intellectual engagement of young scientists working in the area. Therefore, the participation of 29 graduate and postdoctoral students (out of about 135 participants) was a highlight of the meeting. This was the consequence of funding contributions by NSF and NASA.
Extended spaceflight under microgravity conditions leads to significant atrophy of weight-bearing muscles. Atrophy and hypertrophy are the extreme outcomes of the high degree of plasticity exhibited by skeletal muscle. Stimuli which control muscle plasticity include neuronal, hormonal, nutritional, and mechanical inputs. The mechanical stimulus for muscle is directly related to the work or exercise against a load performed. Little or no work is performed by weight-bearing muscles under microgravity conditions. A major hypothesis is that focal adhesion kinase (FAK) which is associated with integrin at the adherens junctions and costa meres of all skeletal muscles is an integral part of the major mechanism for molecular signaling upon mechanical stimulation in all muscle fibers. Additionally, we propose that myotonic protein kinase (DMPK) and dystrophin (DYSTR) also participate in distinct mechanically stimulated molecular signaling pathways that are most critical in type I and type II muscle fibers, respectively. To test these hypotheses, we will use the paradigms of hindlimb unloading and overloading in mice as models for microgravity conditions and a potential exercise countermeasure, respectively, in mice. We expect that FAK loss-of-function will impair hypertrophy and enhance atrophy in all skeletal muscle fibers whereas DYSTR and DMPK loss-of-function will have similar but more selective effects on Type IT and Type I fibers, respectively. Gene expression will be monitored by muscle-specific creatine kinase M promoter-reporter construct activity and specific MRNA and protein accumulation in the soleus (type I primarily) and plantaris (type 11 primarily) muscles. With these paradigms and assays, the following Specific Project Aims will be tested in genetically altered mice: 1) identify the roles of DYSTR and its pathway; 2) evaluate the roles of the DMPK and its pathway; 3) characterize the roles of FAK and its pathway and 4) genetically analyze the mechanisms and interactions between the FAK, DYSTR, and DMPK-associated pathways in single and specific combinations of mutants. The identification of potential signaling mechanisms may permit future development of pharmacological countermeasures for amelioration and prevention of the microgravity-induced atrophy in extended spaceflight, and the analysis of both overloading and unloading paradigms may provide further support for development of exercise-based countermeasures. Understanding the basic mechanisms of molecular signaling in muscle plasticity may aid our understanding and treatment of skeletal muscle atrophy not only in spaceflight but in similar problems of the aging population, in prolonged bed rest, and in cachexia associated with chronic disease.
The major goal of these studies was to continue investigations into the influence of altered gravitational fields on the development and function of the vertebrate brain and nervous system. Of major focus during the 18-month finding period of this award was the maintenance of the animals used in the experimental mouse and medaka model paradigms. The experiments focused on characterization of stress-sensitive periods in neural development and immediate or delayed effects on gene expression, physiology and behavior. The hypothesis under investigation was that the environment of space will have biologically significant effects on the development and function of the vertebrate nervous system. We have postulated that these effects will be more significant on certain neural compartments, such as the vestibular-motor system, and that these effects will have greater impact at particular stages of embryonic and post-natal development of the animal. Development of the central nervous system is well known for its vulnerability and sensitivity to environmental stimuli, although the effects of gravitational influences are poorly understood. The long-term goals of this research effort, initiated previously and continued in limited capacity during this interim period, were to provide important new information on the effects of altered environments during these critical periods.
We introduce a statistical data model and an associated optimization-based clustering algorithm which allows data vectors to belong to zero, one or several "parent" clusters. For each data vector the algorithm makes a discrete decision among these alternatives. Thus, a recursive version of this algorithm would place data clusters in a Directed Acyclic Graph rather than a tree. We test the algorithm with synthetic data generated according to the statistical data model. We also illustrate the algorithm using real data from large-scale gene expression assays.
Atmospheric latent heating field is fundamental to all modes of atmospheric circulation and upper mixed layer circulations of the ocean. The key to understanding the atmospheric heating process is understanding how and where precipitation occurs. The principal atmospheric processes which link precipitation to atmospheric circulation include: (1) convective mass fluxes in the form of updrafts and downdrafts; (2) microphysical. nucleation and growth of hydrometeors; and (3) latent heating through dynamical controls on the gravitation-driven vertical mass flux of precipitation. It is well-known that surface and near-surface rainfall are two of the key forcing functions on a number of geophysical parameters at the surface-air interface. Over ocean, rainfall variation contributes to the redistribution of water salinity, sea surface temperature, fresh water supply, and marine biology and eco-system. Over land, rainfall plays a significant role in rainforest ecology and chemistry, land hydrology and surface runoff. Precipitation has also been closely linked to a number of atmospheric anomalies and natural hazards that occur at various time scales, including hurricanes, cyclones, tropical depressions, flash floods, droughts, and most noticeable of all, the El Ninos. From this point of view, the significance of global atmospheric precipitation has gone far beyond the science arena - it has a far-reaching impact on human's socio-economic well-being and sustenance. These and many other science applications require the knowledge of, in a global basis, the vertical rain structures, including vertical motion, rain intensity, differentiation of the precipitating hydrometeors' phase state, and the classification of mesoscale physical structure of the rain systems. The only direct means to obtain such information is the use of a spaceborne profiling radar. It is important to mention that the Tropical Rainfall Measuring Mission (TRMM) have made a great stride forward towards this ultimate goal. The Precipitation Radar (PR) aboard the TRMM satellite is the first ever spaceborne radar dedicated to three-dimensional, global precipitation measurements over the tropics and the subtropics, as well as the detailed synopsis of a wide range of tropical rain storm systems. In only twelve months since launch, the PR, together with other science instruments abroad the satellite have already provided unprecedented insights into the rainfall systems. It is anticipated the a lot more exciting and important rain observations would be made by TRMM throughout its mission duration. While TRMM has provided invaluable data to the user community, it is only the first step towards advancing our knowledge on rain processes and its contributions to climate variability. It is envisioned that a TRMM follow-on mission is needed in such a way to capitalize on the pioneering information provided by TRMM, and its instrument capability must be extended beyond TRMM in such a way to fully address the key science questions from microphysical to climatic time scale. In fact, a number of new and innovative mission concepts have recently put forth for this purpose. Almost all of these new concepts have suggested the utility of a more advanced, high-resolution, Doppler-enabled, vertical profiling radar that can provide multi-parameter observations of precipitation. In this paper, a system concept for a second- gene ration precipitation radar (PR-2) which addresses the above requirements will be described.
There have been substantial advances in molecular and cellular biology that have provided new insight into the biochemical and genetic basis of lymphocyte recognition, activation and expression of distinct functional phenotypes. It has now become evident that for both T and B cells, stimuli delivered through their receptors can result in either clonal expansion or apoptosis. In the case of T cells, clonal expansion of helper cells is accompanied by differentiation into two major functional subsets which regulate the immune response. The pathways between the membrane and the nucleus and their molecular components are an area of very active investigation. This meeting will draw together scientists working on diverse aspects of this problem, including receptor ligand interactions, intracellular pathways that transmit receptor mediated signals and the effect of such signal transduction pathways on gene regulation. The aim of this meeting is to integrate the information from these various experimental approaches into a new synthesis and molecular explanation of T cell activation, differentiation and death.
Early in the development of the Crew Health Care System (CHECS) for the International Space Station (ISS), it was recognized that detection of target volatile organic compounds would be a key component of the air monitoring strategy. Experiences during the NASA/Mir program supported the decision to include a real-time volatile organic analyzer (VOA) aboard ISS to help assess the impact of air quality events on crew health and determine the effectiveness of decontamination efforts. Toward this end, a joint development by the Toxicology Laboratory at Johnson Space Center and Graseby Dynamics produced a VOA that has been delivered and is ready for the first 5 years of ISS operation. The first-generation VOA selection criteria included minimizing size, weight, and power consumption while maintaining analytical performance. Measuring available technologies against these criteria, a VOA system based upon gas chromatography/ion mobility spectrometry (GC/IMS) was selected in the mid-90's. However, as NASA looks forward to later-stage ISS operations and to new frontiers such as human exploration of Mars, the ISS VOA (weighing 43 kg and consuming 160 watts) must be replaced by a smaller, less resource-intensive device. This paper will present a possible second-gene ration VOA based upon the same technology as the first-generation unit. Utilizing GC/IMS technology again will permit the instrumental data and experience gained during the initial phase of ISS to be applied to later ISS phases and advanced spacecraft missions. During the past 3 years, efforts to reduce the size of ion mobility spectrometers have been pursued by Graseby Dynamics, the manufacturer of the first-generation VOA. The concept of operation, expected analytical performance, and estimated size of a fully functional second-generation VOA based upon GC/mini-IMS technology will be presented. Furthermore, results of initial laboratory evaluations will be shown.
A number of basic cellular functions, e.g., electrolyte concentration cell growth rate, glucose utilization, bone formation, response to growth stimulation and exocytosis are modified by microgravity or during spaceflight. Studies with intact animal during spaceflights have found lipid accumulations within the lumen of the vasculature and degeneration of the vascular wall. Capillary alterations with extensive endothelial invaginations were also seen. Hemodynamic studies have shown that there is a redistribution of blood from the lower extremities to the upper part of the body; this will alter vascular permeability, resulting in leakage into surrounding tissues. These studies indicate that changes in gravity will affect a number of physiological systems, including the vasculature. However, few studies have addressed the effect of microgravity on vascular cell function and metabolism. A major problem with ground based studies is that achieving a true microgravity hand, environment for prolonged period is not possible. On the other increasing gravity (i.e., hypergravity) is easily achieved. Several researchers have shown that hypergravity will increase the proliferation of several different cell limes (e.g., chick embryo fibroblasts) while decreasing cell motility and slowing liver regeneration following partial hepatectomy. These studies suggest that hypergravity will alter the behavior of most cells. Several investigators have shown that hypergravity affects the expression of the early response genes (c-fos and c-myc) and the activation of several protein kinases (PK's) in cells (10,11). In this study we investigated whether hypergravity alters the expression of f-actin by aortic endothelial cells, and the possible role of protein kinases (calmodulin(II)-dependent and PKA) as mediators of these effects.
The proton-translocating ATPases are multimeric enzymes that carry out a multitude of essential functions. Their origin and evolution represent a seminal event in the early evolution of life. Amino acid sequences of the two largest subunits from archaeal ATPases (A-ATPases), vacuolar ATPases (V-ATPases), and FOF1-ATP syntheses (FATPases) suggest these ATPases evolved from an ancestral vacuolar-like ATP syntheses. A necessary consequence of this notion is that the A-ATPases are ATP syntheses. With the possible exception of the A-ATPase from Halobacterium salinarium. no A-ATPase has been demonstrated to synthesize ATP. The evidence for this case is dubious since ATP synthesis occurs only when conditions are distinctively unphysiological. We demonstrated that ATP synthesis in H.saccharovorum is inconsistent with the operation of an A-type ATPase. In order to determine if this phenomenon was unique to H. saccharovorum, ATP synthesis was examined in various extremely halophilic bacteria with the goal of ascertaining if it resembled what occurred in a. saccharovorum, or was consistent with the operation of an A-type ATPase. A-, V-, and F-type ATPases respond singularly to certain inhibitors. Therefore, the effect of these inhibitors on ATP synthesis in several extreme halophiles was determined. Inhibitors that either blocked or collapsed proton-gradients inhibited the steady state synthesis of ATP thus verifying that synthesis took place at the expense of a proton gradient. Azide, an inhibitor of F-ATPases inhibited ATP synthesis. Since the arginine-dependent synthesis of ATP, which occurs by way of substrate-level phosphorylation, was unaffected by azide, it was unlikely that azide acted as an "uncoupler." N -ethylmaleimide and nitrate, which inhibit V- and A-ATPases, either did not inhibit ATP synthesis or resulted in higher steady-state levels of ATP. These results suggest there are two types of proton-motive ATPases in the extreme halophiles (and presumably in other Archaea). One, the V-like enzyme which, provides protons that are subsequently used for solute translocation. The other ATPase is the familiar and ubiquitous F-ATPase that functions as a reversible proton pump and is the ATP Synthase in the extreme halophiles. Thus, while the suggested evolution of the proton -translocating ATPases accounts for the relationship among these ATPases, this scheme does not account for the presence of F-ATPases in the Archaea. Discounting lateral gene transfer, perhaps an F-type ATPase evolved before the eucaryal-archaeal and bacterial bifurcation. The presence of V-type ATPases in the Bacterial Domain is consistent with this suggestion. Finally, it is of interest to note that if an F-type ATPase appeared before the bifurcation, an endosymbiotic event need not be invoked to explain the presence of F-ATPases in the Eucarya.
The primary goal of the project was to develop a ground based model to first study the role of the nerve and of thyroid hormone (T3) in the regulation of body growth and skeletal muscle growth and differentiation in rodents. A primary objective was to test the hypothesis that normal weight bearing activity is essential for the development of antigravity, slow twitch skeletal muscle and the corresponding slow myosin heavy chain (MHC) gene; whereas, T3 was obligatory for general body and muscle growth and the establishment of fast MHC phenotype in typically fast locomoter muscles. These ground based experiments would provide both the efficacy and background for a spaceflight experiment (referred to as the Neurolab Mission) jointly sponsored by the NIH and NASA.
The two experiments housed in the Commercial Generic Bioprocessing Apparatus (CGBA) during STS-106 were designed to explore how biological processes are affected by microgravity. The first was a developmental study into the effects of microgravity on motor-neuronal growth in the fruit fly species Drosophila melanogaster and the second study was designed to characterize changes in kidney cell gene expression. The objective of the primary experiment, called NIH-B1, was to determine how gravity affects neuronal development of the D. melanogaster embryo and larvae in microgravity, specifically observing the neural connections to muscle fibers.
This paper will describe a series of field experiments to develop and demonstrate file use of Telepresence and Virtual Reality systems for controlling rover vehicles on planetary surfaces. In 1993, NASA Ames deployed a Telepresence-Controlled Remotely Operated underwater Vehicle (TROV) into an ice-covered sea environment in Antarctica. The goal of the mission was to perform scientific exploration of an unknown environment using a remote vehicle with telepresence and virtual reality as a user interface. The vehicle was operated both locally, from above a dive hole in the ice through which it was launched, and remotely over a satellite communications link from a control room at NASA's Ames Research center, for over two months. Remote control used a bidirectional Internet link to the vehicle control computer. The operator viewed live stereo video from the TROV along with a computer-gene rated graphic representation of the underwater terrain showing file vehicle state and other related information. Tile actual vehicle could be driven either from within the virtual environment or through a telepresence interface. In March 1994, a second field experiment was performed in which [lie remote control system developed for the Antarctic TROV mission was used to control the Russian Marsokhod Rover, an advanced planetary surface rover intended for launch in 1998. Marsokhod consists of a 6-wheel chassis and is capable of traversing several kilometers of terrain each day, The rover can be controlled remotely, but is also capable of performing autonomous traverses. The rover was outfitted with a manipulator arm capable of deploying a small instrument, collecting soil samples, etc. The Marsokhod rover was deployed at Amboy Crater in the Mojave desert, a Mars analog site, and controlled remotely from Los Angeles. in two operating modes: (1) a Mars rover mission simulation with long time delay and (2) a Lunar rover mission simulation with live action video. A team of planetary geologists participated in the mission simulation. The scientific goal of the science mission was to determine what could be learned about the geologic context of the site using the capabilities of imaging and mobility provided by the Marsokhod system in these two modes of operation. I will discuss the lessons learned from these experiments in terms of the strategy for performing Mars surface exploration using rovers. This research is supported by the Solar System Exploration Exobiology, Geology, and Advanced Technology programs.
Flight Director Gene Krantz gives an overview of the Apollo 13 mission as corrections are made in the power down checklist, passive thermal control, and orbital burns after the spacecraft runs into problems. He then answers questions from the press with the help of Tony England, Bill Peters, and Dick Thorson. Footage then shows newspaper headlines 'We're Not Concerned' and 'Getting Ready to Land' as people watch televisions to see if the astronauts landed safely. The press conference section of this video has sound, the headlines section does not.
The direct detection of organic biomarkers for living or fossil microbes on Mars by an in situ instrument is a worthy goal for future lander missions. Several new and innovative biotechnology approaches are being explored. Firstly we have proposed an instrument based on immunological reactions to specific antibodies to cause activation of fluorescent stains. Antibodies are raised or acquired to a variety of general and specific substances that might be in Mars soil. These antibodies are then combined with various fluorescent stains and applied to micron sized numbered spots on a small (2-3 cm) test plate where they become firmly attached after freeze drying. Using technology that has been developed for gene mining in DNA technology up to 10,000 tests per square inch can now be applied to a test plate. On Mars or the planet/moon of interest, a sample of soil from a trench or drill core is extracted with water and/or an organic solvent and ultrasonication and then applied to the test plate. Any substance, which has an antibody on the test plate, will react with its antibody and activate its fluorescent stain. At the moment a small UV light source will illuminate the test plate, which is observed with a small CCD camera, although other detection systems will be applied. The numbered spots that fluoresce indicate the presence of the tested-for substance, and the intensity indicates relative amounts. Furthermore with up to a thousand test plates available false positives and several variations of antibody can also be screened for. The entire instrument can be quite small and light, on the order of 10 cm in each dimension. A possible choice for light source may be small UV lasers at several wavelengths. Some of the wells or spots can contain simply standard fluorescent stains used to detect live cells, dead cells, DNA, etc. The stains in these spots may be directly activated, with no antibodies being necessary. The proposed system will look for three classes of biomarkers: those from extant life, such as DNA, those from extinct life such as hopanes, and those from organic compounds not necessarily associated with life such as PAHs, rocket exhaust contamination and other a/pre-biotic chemicals. Both monoclonal and polyclonal antibodies can be used. Monoclonal antibodies react with a very specific compound, but polyclonal antibodies may react to any of a whole family of compounds. Furthermore the technique of phage display to raise antibodies against classically non-antigenic molecules is also being considered. Additional information is contained in the original extended abstract.
The Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) is a UH-60A Black Hawk helicopter that is being modified by the US Army and NASA for flight systems research. The principal systems that are being installed in the aircraft are a Helmet Mounted Display (HMD) and imaging system, and a programmable full authority Research Flight Control System (RFCS). In addition, comprehensive instrumentation of both the rigid body of the helicopter and the rotor system is provided. The paper will describe the capabilities of these systems and their current state of development. A brief description of initial research applications is included. The wide (40 X 60 degree) field-of-view HMD system has been provided by Kaiser Electronics. It can be configured as a monochromatic system for use in bright daylight conditions, a two color system for darker ambients, or a full color system for use in night viewing conditions. Color imagery is achieved using field sequential video and a mechanical color wheel. In addition to the color symbology, high resolution computer-gene rated imagery from an onboard Silicon Graphics Reality Engine Onyx processor is available for research in virtual reality applications. This synthetic imagery can also be merged with real world video from a variety of imaging systems that can be installed easily on the front of the helicopter. These sensors include infrared or tv cameras, or potentially small millimeter wave radars. The Research Flight Control System is being developed for the aircraft by a team of contractors led by Boeing Helicopters. It consists of a full authority high bandwidth fly-by-wire actuators that drive the main rotor swashplate actuators and the tail rotor actuator in parallel. This arrangement allows the basic mechanical flight control system of the Black Hawk to be retained so that the safety pilot can monitor the operation of the system through the action of his own controls. The evaluation pilot will signal the fly-by-wire actuators through the flight computer from electrical sidearm controllers located in the right hand cockpit. The system will have very substantial input/output capacity and impressive computational power. These systems are installed in the aircraft using predominantly a MIL-STD 1553B data bus architecture. Sensor data from the RFCS, the basic aircraft and rotor system instrumentation including navigation information, and the HMD system are easily exchanged among user systems, or are available at the systems operator station located in the cabin for real time monitoring or data recording.