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At least 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Hypertonicity-induced transmitter release at Drosophila neuromuscular junctions is partly mediated by integrins and cAMP/protein kinase A

The frequency of quantal transmitter release increases upon application of hypertonic solutions. This effect bypasses the Ca(2+) triggering step, but requires the presence of key molecules involved in vesicle fusion, and hence could be a useful tool for dissecting the molecular process of vesicle fusion. We have examined the hypertonicity response at neuromuscular junctions of Drosophila embryos in Ca(2+)-free saline. Relative to wild-type, the response induced by puff application of hypertonic solution was enhanced in a mutant, dunce, in which the cAMP level is elevated, or in wild-type embryos treated with forskolin, an activator of adenylyl cyclase, while protein kinase A (PKA) inhibitors decreased it. The response was also smaller in a mutant, DC0, which lacks the major subunit of PKA. Thus the cAMP/PKA cascade is involved in the hypertonicity response. Peptides containing the sequence Arg-Gly-Asp (RGD), which inhibit binding of integrins to natural ligands, reduced the response, whereas a peptide containing the non-binding sequence Arg-Gly-Glu (RGE) did not. A reduced response persisted in a mutant, myospheroid, which expresses no integrins, and the response in DC0 was unaffected by RGD peptides. These data indicate that there are at lease two components in the hypertonicity response: one that is integrin mediated and involves the cAMP/PKA cascade, and another that is not integrin mediated and does not involve the cAMP/PKA cascade.

NASA Discipline Cell Biology↗
NASA NTRS1995

Potential ligand-binding residues in rat olfactory receptors identified by correlated mutation analysis

A family of G-protein-coupled receptors is believed to mediate the recognition of odor molecules. In order to identify potential ligand-binding residues, we have applied correlated mutation analysis to receptor sequences from the rat. This method identifies pairs of sequence positions where residues remain conserved or mutate in tandem, thereby suggesting structural or functional importance. The analysis supported molecular modeling studies in suggesting several residues in positions that were consistent with ligand-binding function. Two of these positions, dominated by histidine residues, may play important roles in ligand binding and could confer broad specificity to mammalian odor receptors. The presence of positive (overdominant) selection at some of the identified positions provides additional evidence for roles in ligand binding. Higher-order groups of correlated residues were also observed. Each group may interact with an individual ligand determinant, and combinations of these groups may provide a multi-dimensional mechanism for receptor diversity.

NASA Discipline Neuroscience↗
NASA NTRS1997

Identification of the prooxidant site of human ceruloplasmin: a model for oxidative damage by copper bound to protein surfaces

Free transition metal ions oxidize lipids and lipoproteins in vitro; however, recent evidence suggests that free metal ion-independent mechanisms are more likely in vivo. We have shown previously that human ceruloplasmin (Cp), a serum protein containing seven Cu atoms, induces low density lipoprotein oxidation in vitro and that the activity depends on the presence of a single, chelatable Cu atom. We here use biochemical and molecular approaches to determine the site responsible for Cp prooxidant activity. Experiments with the His-specific reagent diethylpyrocarbonate (DEPC) showed that one or more His residues was specifically required. Quantitative [14C]DEPC binding studies indicated the importance of a single His residue because only one was exposed upon removal of the prooxidant Cu. Plasmin digestion of [14C]DEPC-treated Cp (and N-terminal sequence analysis of the fragments) showed that the critical His was in a 17-kDa region containing four His residues in the second major sequence homology domain of Cp. A full length human Cp cDNA was modified by site-directed mutagenesis to give His-to-Ala substitutions at each of the four positions and was transfected into COS-7 cells, and low density lipoprotein oxidation was measured. The prooxidant site was localized to a region containing His426 because CpH426A almost completely lacked prooxidant activity whereas the other mutants expressed normal activity. These observations support the hypothesis that Cu bound at specific sites on protein surfaces can cause oxidative damage to macromolecules in their environment. Cp may serve as a model protein for understanding mechanisms of oxidant damage by copper-containing (or -binding) proteins such as Cu, Zn superoxide dismutase, and amyloid precursor protein.

NASA Discipline Regulatory Physiology↗
NASA NTRS2005

Production of Functional Proteins: Balance of Shear Stress and Gravity

The present invention provides for a method of culturing cells and inducing the expression of at least one gene in the cell culture. The method provides for contacting the cell with a transcription factor decoy oligonucleotide sequence directed against a nucleotide sequence encoding a shear stress response element.

Goodwin, Thomas John↗
NASA NTRS2014

Rapid Polymer Sequencer

Solid-state nanopore-based analysis of nucleic acid polymers is revolutionary. No other technique can determine information content in single molecules of genetic material at the speed of 1 subunit per microsecond. Because individual molecules are counted, the output is intrinsically quantitative. The nanopore approach is more generalized than any other method and in principle may be used to analyze any polymer molecule, including proteins. The approach to the development of a solid-state nanopore device is novel in the use of nanofabrication, nanoelectronic components, and high-speed signal acquisition. A novel geometry of the solid-state nanopore (less than 5 nm in length and 5 nm in diameter) will enable 1 to 5 nucleotide resolution measurements. This means that maximum resolution will be improved at least 100-fold compared to biological ion-channel measurements. The solid-state nanopore sensor will be made to enable sequencing DNA at a much faster rate than presently possible without the need for extensive sample preparation procedures, such as enzymatic amplification and labeling reactions. It will analyze electronic properties of individual subunits of DNA or RNA, to obtain linear composition of each genetic polymer molecule.

technology opportunity↗
NASA NTRS1992

Origin and early evolution of photosynthesis

Photosynthesis was well-established on the earth at least 3.5 thousand million years ago, and it is widely believed that these ancient organisms had similar metabolic capabilities to modern cyanobacteria. This requires that development of two photosystems and the oxygen evolution capability occurred very early in the earth's history, and that a presumed phase of evolution involving non-oxygen evolving photosynthetic organisms took place even earlier. The evolutionary relationships of the reaction center complexes found in all the classes of currently existing organisms have been analyzed using sequence analysis and biophysical measurements. The results indicate that all reaction centers fall into two basic groups, those with pheophytin and a pair of quinones as early acceptors, and those with iron sulfur clusters as early acceptors. No simple linear branching evolutionary scheme can account for the distribution patterns of reaction centers in existing photosynthetic organisms, and lateral transfer of genetic information is considered as a likely possibility. Possible scenarios for the development of primitive reaction centers into the heterodimeric protein structures found in existing reaction centers and for the development of organisms with two linked photosystems are presented.

NASA Program Exobiology↗
NASA NTRS1998

1,25-Dihydroxyvitamin D3 inhibition of col1a1 promoter expression in calvariae from neonatal transgenic mice

We studied the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on organ cultures of transgenic mouse calvariae containing segments of the Col1a1 promoter extending to -3518, -2297, -1997, -1794, -1763, and -1719 bp upstream of the transcription start site fused to the chloramphenicol acetyltransferase (CAT) reporter gene. 1,25(OH)2D3 had a dose-dependent inhibitory effect on the expression of the -3518 bp promoter construct (ColCAT3.6), with maximal inhibition of about 50% at 10 nM. This level of inhibition was consistent with the previously observed effect on the endogenous Col1a1 gene in bone cell models. All of the shorter constructs were also inhibited by 10 nM 1,25(OH)2D3, suggesting that the sequences required for 1, 25(OH)2D3 inhibition are downstream of -1719 bp. The inhibitory effect of 1,25(OH)2D3 on transgene mRNA was maintained in the presence of the protein synthesis inhibitor cycloheximide, suggesting that the inhibitory effect on Col1a1 gene transcription does not require de novo protein synthesis. We also examined the in vivo effect of 1,25(OH)2D3 treatment of transgenic mice on ColCAT activity, and found that 48 h treatment caused a dose-dependent inhibition of CAT activity in calvariae comparable to that observed in organ cultures. In conclusion, we demonstrated that 1,25(OH)2D3 inhibits Col1A1 promoter activity in transgenic mouse calvariae, both in vivo and in vitro. The results indicate that there is a 1, 25(OH)2D3 responsive element downstream of -1719 bp. The inhibitory effect does not require new protein synthesis.

NASA Discipline Cell Biology↗
NASA NTRS2007

NASA Tech Briefs, December 2007

Topics include: Ka-Band TWT High-Efficiency Power Combiner for High-Rate Data Transmission; Reusable, Extensible High-Level Data-Distribution Concept; Processing Satellite Imagery To Detect Waste Tire Piles; Monitoring by Use of Clusters of Sensor-Data Vectors; Circuit and Method for Communication Over DC Power Line; Switched Band-Pass Filters for Adaptive Transceivers; Noncoherent DTTLs for Symbol Synchronization; High-Voltage Power Supply With Fast Rise and Fall Times; Waveguide Calibrator for Multi-Element Probe Calibration; Four-Way Ka-Band Power Combiner; Loss-of-Control-Inhibitor Systems for Aircraft; Improved Underwater Excitation-Emission Matrix Fluorometer; Metrology Camera System Using Two-Color Interferometry; Design and Fabrication of High-Efficiency CMOS/CCD Imagers; Foam Core Shielding for Spacecraft CHEM-Based Self-Deploying Planetary Storage Tanks Sequestration of Single-Walled Carbon Nanotubes in a Polymer PPC750 Performance Monitor Application-Program-Installer Builder Using Visual Odometry to Estimate Position and Attitude Design and Data Management System Simple, Script-Based Science Processing Archive Automated Rocket Propulsion Test Management Online Remote Sensing Interface Fusing Image Data for Calculating Position of an Object Implementation of a Point Algorithm for Real-Time Convex Optimization Handling Input and Output for COAMPS Modeling and Grid Generation of Iced Airfoils Automated Identification of Nucleotide Sequences Balloon Design Software Rocket Science 101 Interactive Educational Program Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites Dog-Bone Horns for Piezoelectric Ultrasonic/Sonic Actuators Benchtop Detection of Proteins Recombinant Collagenlike Proteins Remote Sensing of Parasitic Nematodes in Plants Direct Coupling From WGM Resonator Disks to Photodetectors Using Digital Radiography To Image Liquid Nitrogen in Voids Multiple-Parameter, Low-False-Alarm Fire-Detection Systems Mosaic-Detector-Based Fluorescence Spectral Imager Plasmoid Thruster for High Specific-Impulse Propulsion Analysis Method for Quantifying Vehicle Design Goals Improved Tracking of Targets by Cameras on a Mars Rover Sample Caching Subsystem Multistage Passive Cooler for Spaceborne Instruments GVIPS Models and Software Stowable Energy-Absorbing Rocker-Bogie Suspensions

Source record↗
NASA NTRS2010

The Earliest Ion Channels in Protocellular Membranes

Cellular membranes with their hydrophobic interior are virtually impermeable to ions. Bulk of ion transport through them is enabled through ion channels. Ion channels of contemporary cells are complex protein molecules which span the membrane creating a cylindrical pore filled with water. Protocells, which are widely regarded as precursors to modern cells, had similarly impermeable membranes, but the set of proteins in their disposal was much simpler and more limited. We have been, therefore, exploring an idea that the first ion channels in protocellular membranes were formed by much smaller peptide molecules that could spontaneously selfassemble into short-lived cylindrical bundles in a membrane. Earlier studies have shown that a group of peptides known as peptaibols is capable of forming ion channels in lipid bilayers when they are exposed to an electric field. Peptaibols are small, non-genetically encoded peptides produced by some fungi as a part of their system of defense against bacteria. They are usually only 14-20 residues long, which is just enough to span the membrane. Their sequence is characterized by the presence of non-standard amino acids which, interestingly, are also expected to have existed on the early earth. In particular, the presence of 2-aminoisobutyric acid (AIB) gives peptaibols strong helix forming propensities. Association of the helices inside membranes leads to the formation of cylindrical bundles, typically containing 4 to 10 monomers. Although peptaibols are excellent candidates for models of the earliest ion channels their structures, which are stabilized only by van der Waals forces and occasional hydrogen bonds between neighboring helices, are not very stable. Although it might properly reflect protobiological reality, it is also a major obstacle in studying channel behavior. For this reason we focused on two members of the peptaibol family, trichotoxin and antiamoebin, which are characterized by a single conductance level. This indicates that their structures are unique and stable. In addition, it is also believed that the trichotoxin channel displays some selectivity between potassium and chloride ions. This makes trichotoxin and antiamoebin ideal models of the earliest ion channels that could provide insight into the origins of ion conductance and selectivity. In the absence of crystal structure of the trichotoxin and antiamoebin channels, we propose their molecular models based on experimentally determined number of monomers forming the bundles. We use molecular dynamics simulations to validate the models in terms of their conductance and selectivity. On the basis of our simulations we show that the emergence of channels built of small, alpha-helical peptides was protobiologically plausible and did not require highly specific amino acid sequences, which is a convenient evolutionary trait. Despite their simple structure, such channels could possess properties that, at the first sight, appear to require markedly larger complexity. To this end, we will discuss how the amino acid sequence and structure of primitive channels give rise to the phenomena of ionic conductance and selectivity across the earliest cell walls, which were essential functions for the emergence and early evolution of protocells. Furthermore, we will argue that even though architectures of membrane proteins are not nearly as diverse as those of water-soluble proteins, they are sufficiently flexible to adapt readily to the functional demands arising during evolution.

Mijajlovic, Milan↗
NASA NTRS2001

Differential global gene expression in red and white skeletal muscle

The differences in gene expression among the fiber types of skeletal muscle have long fascinated scientists, but for the most part, previous experiments have only reported differences of one or two genes at a time. The evolving technology of global mRNA expression analysis was employed to determine the potential differential expression of approximately 3,000 mRNAs between the white quad (white muscle) and the red soleus muscle (mixed red muscle) of female ICR mice (30-35 g). Microarray analysis identified 49 mRNA sequences that were differentially expressed between white and mixed red skeletal muscle, including newly identified differential expressions between muscle types. For example, the current findings increase the number of known, differentially expressed mRNAs for transcription factors/coregulators by nine and signaling proteins by three. The expanding knowledge of the diversity of mRNA expression between white and mixed red muscle suggests that there could be quite a complex regulation of phenotype between muscles of different fiber types.

Non-NASA Center↗
NASA NTRSDate not supplied

The maize rough endosperm6 (rgh6) mutant encodes a predicted DEAD-box RNA helicase

Maize rough endosperm (rgh) mutants have defective seeds with a rough, etched, or pitted endosperm surface. Molecular genetic analysis of this mutant class has identified multiple RNA processing proteins critical to endosperm development. We isolated the rgh6 locus from the UniformMu transposon tagging population. Mutant kernels have reduced grain-fill with defective embryos that fail to germinate. Self-pollination of rgh6 heterozygotes produces mutant seeds at frequency consistent with a single recessive mutation. Molecular mapping localized rgh6 to a 60 kbp interval on chromosome 5. PCR analysis of gene models within the fine-map interval identified a Mutator (Mu) transposon insertion within a predicted DEAD-box RNA helicase gene. A second allele of rgh6 was identified from UniformMu population. Reciprocal crosses between rgh6-umu1 and rgh6-umu2 heterozygotes produces mutant seeds at a frequency consistent with a 3:1 ratio indicating these mutants are allelic. Both rgh6-umu1 and rgh6-umu2 have Mu element insertions at the same insertion site within the DEAD-box RNA helicase gene. However, the terminal inverted repeat sequences are polymorphic between the alleles showing the alleles are independent mutations. We conclude that mutation of the DEAD-box RNA helicase causes the rgh6 phenotype. Further characterization of the rgh6 mutant phenotype and biochemical investigation of the RGH6 protein is expected to give further insights on the roles of RNA processing in endosperm development.

maize↗
NASA NTRSDate not supplied

Rational Design of Nanoplasmonic Array Geometries for Biosensing

Background: Molecular diagnostics provide early and accurate diagnosis, which is essential for the prevention and treatment of infectious as well as chronic diseases. These tests are designed to detect disease-specific bioanalytes such as nucleic acid (DNA or RNA) or protein (antigens, antibodies) biomarkers. In the context of infectious disease diagnosis, nucleic acid-based detection methods are known to provide more specific and sensitive results. Here, the presence of a unique sequence belonging to the pathogenic genomic material is targeted to identify species, organism, genera and/or antimicrobial resistant gene markers. The majority of the common nucleic acid based diagnostic techniques require amplification (polymerase chain reaction, isothermal amplification etc.) of the pathogenic genetic material prior to detection impacting diagnostic speed, complexity, and cost thereby limiting ease of use. Thus, the development of simplified nucleic acid-based diagnostics that can be even used in resource-poor settings may hugely benefit patients across the globe. Nanopath is a molecular diagnostics company utilizing a solid-state nanosensor to enable sequence-specific detection of target nucleic acids without the need of amplification. These nanostructures enable ultra-sensitive biomarker detection using geometric, feature-dependent properties highly dependent on the local dielectric environment, allowing them to be sensitive to low concentration binding events. This paper describes an application of this approach to provide highly relevant clinical information within a single doctor’s office visit. Intro: The Nanopath team is in collaboration with NASA (National Aeronautics and Space Administration) and NIST (National Institute of Standards and Technology) to push the bounds of the fundamental physics associated with their biosensing platform. The ability of metals to support electromagnetic surface waves gives rise to surface plasmons when optically illuminated. This property, and its strong sensitivity to changes in the local refractive index, allows for the use of metal nanoparticles as ultra-sensitive transducers. In prior work by members of this team, ensembles of randomly oriented nanoparticles (i.e., colloidal nanorods dispersed on chip) were employed for sequence-specific nucleic acid sensing (1-3). While these particle sensors have the advantage of rapid fabrication, they suffer from low sensitivity and quality factor due to the random particle dispersity. In contrast, in this study we employ ordered array nanoparticle ensembles which can be used to improve sensor sensitivity and figure-of-merit. Study Methods Overview: In this talk, we detail the results of sensing experiments and computational simulations to outline a rational design of the structure of these plasmonic nanoparticle arrays for biomolecular sensing. Through simulation and experiment, we iteratively tailor nanostructure dimension to provide high quality signal and large resonance shifts upon modeled nucleic acid binding. In particular, full-wave electromagnetic simulations were conducted using Lumerical photonic simulation software in which periodic boundary conditions were applied in the x- and y- dimensions for each of the nanoplasmonic sensor geometries. To simulate the resonance response to changes in the bulk solution in contact with the sensor surface, the refractive index of the surrounding media was changed appropriately. Nucleic acid hybridization events were modeled using either using spherical structures approximating the relevant radius of genomic material as estimated by polymer models, or as conformal layers with the known refractive indices for nucleic acids. On the basis of initial simulations, nanosensors were fabricated using traditional electron-beam lithography protocols at NIST. To evaluate consensus between simulations and experiments, bulk sensing experiments were carried out in which the resonance peaks were obtained by submerging the sensors in refractive index standards. Key nanosensor characteristics including resonance peak locations, resonance peak shifts as a function of refractive index, and figure of merit (FOM) of extinction curves were examined between the experimental and simulation results prior to proceeding with simulations on additional geometries and more complex solution conditions, and further device fabrication. This iterative process is repeated toward a rational design of nanoplasmonic array geometries for biosensing optimizing response for targeted disease detection. In summary, this study puts forth a methodology for rational design and characterization of regularly spaced nanoparticle arrays for optics-based biosensing. The results of this study will allow for more informed design of nanostructure geometries towards sequence-specific nucleic acid detection. These improved designs have the potential to improve clinical sensitivity and limit-of-detection across disease indication.

sensor↗
NASA NTRS1995

Isolation, characterization, and primary structure of rubredoxin from the photosynthetic bacterium, Heliobacillus mobilis

Rubredoxin is a small nonheme iron protein that serves as an electron carrier in bacterial systems. Rubredoxin has now been isolated and characterized from the strictly anaerobic phototroph, Heliobacillus mobilis. THe molecular mass (5671.3 Da from the amino acid sequence) was confirmed and partial formylation of the N-terminal methionyl residue was established by matrix-assisted laser desorption mass spectroscopy. The complete 52-amino-acid sequence was determined by a combination of N-terminal sequencing by Edman degradation and C-terminal sequencing by a novel method using carboxypeptidase treatment in conjunction with amino acid analysis and laser desorption time of flight mass spectrometry. The molar absorption coefficient of Hc. mobilis rubredoxin at 490 nm is 6.9 mM-1 cm-1 and the midpoint redox potential at pH 8.0 is -46 mV. The EPR spectrum of the oxidized form shows resonances at g = 9.66 and 4.30 due to a high-spin ferric iron. The amino acid sequence is homologous to those of rubredoxins from other species, in particular, the gram-positive bacteria, and the phototrophic green sulfur bacteria, and the evolutionary implications of this are discussed.

NASA Discipline Number 52-30↗
NASA NTRS2001

Crystallization of bFGF-DNA Aptamer Complexes Using a Sparse Matrix Designed for Protein-Nucleic Acid Complexes

The Sparse Matrix approach for obtaining lead crystallization conditions has proven to be very fruitful for the crystallization of proteins and nucleic acids. Here we report a Sparse Matrix developed specifically for the crystallization of protein-DNA complexes. This method is rapid and economical, typically requiring 2.5 mg of complex to test 48 conditions. The method was originally developed to crystallize basic fibroblast growth factor (bFGF) complexed with DNA sequences identified through in vitro selection, or SELEX, methods. Two DNA aptamers that bind with approximately nanomolar affinity and inhibit the angiogenic properties of bFGF were selected for co-crystallization. The Sparse Matrix produced lead crystallization conditions for both bFGF-DNA complexes.

Cannone, Jaime J.↗
NASA NTRSDate not supplied

Method Development for In-situ Detection of Latent Herpesvirus DNA from Saliva using Nanopore Sequencing

Research toward latent herpesvirus reactivation has been intensively addressed through Space Shuttle and International Space Station (ISS) investigations. This work has provided the understanding that persistent reactivation of herpesviruses from asymptomatic crew can be detected through viral shedding in saliva, urine, and blood. Occasionally, viral reactivation from the latency stage can pose a threat to crew health (clinical manifestation) before, during, and after flight missions. Furthermore, previous work detailing correlations with immunity indicate that monitoring viral reactivation could be implemented to assess potential immune dysfunction. While in-flight monitoring is desirable, there is no well-established procedure or method for real-time evaluations, and research to date has relied on postflight, ground-based analysis. The development of portable molecular technologies like the miniPCR™ (miniPCR Bio) thermal cycler and the MinION™ sequencer (Oxford Nanopore Technologies) have confirmed that real-time monitoring is possible in extreme and low resource environments. These devices, combined with simple sample preparation methods, have been used to demonstrate bacterial identification onboard the ISS, as well as rapid viral detection in remote locations on Earth. The work here builds upon previous molecular advancements onboard the ISS toward the development and validation of a spaceflight-compatible method for viral detection from crew samples. Several herpesviruses can be detected in saliva, which provides a non-invasive means to collect samples for monitoring. While the basis for this method lies in previous spaceflight investigations, key points for method optimization include DNA extraction from saliva, viral primer selection, and bioinformatic processes for data analysis. To increase viral yield, numerous DNA extraction methods have been evaluated and will be discussed in detail. For initial development and testing, varicella-zoster virus (VZV) is being targeted though open reading frame 51 and 63 (ORF51, ORF63), as the replication origin-binding protein is highly expressed during latency. Optimization of the thermal cycling parameters has resulted in the ability to test the entire process. The full method has been tested with both viral VZV DNA standards and saliva spiked with varying concentrations of VZV. Viral sequence data were mapped to the reference sequence using minimap2. Prior to mapping, DNA sequencing reads were filtered for length and quality, barcodes were removed, and alignment identity calculated. Following further assessments, statistics were compared across multiple sequencing experiments and are being used to determine the success of the protocols. Forward work will include the incorporation of herpes simplex virus 1 (HSV-1) and Epstein-Barr virus (EBV) primers as well as the validation of results to the terrestrial qPCR standard assay. Upon full validation of the developed method, saliva will be collected from 20 healthy subjects and spiked with viral DNA. These samples will be split and assayed with the MinION and standard qPCR assay.

Hang N Nguyen↗
NASA NTRS2003

Isolation and characterization of a novel gene sfig in rat skeletal muscle up-regulated by spaceflight (STS-90)

We obtained the skeletal muscle of rats exposed to weightless conditions during a 16-day-spaceflight (STS-90). By using a differential display technique, we identified 6 up-regulated and 3 down-regulated genes in the gastrocnemius muscle of the spaceflight rats, as compared to the ground control. The up-regulated genes included those coding Casitas B-lineage lymphoma-b, insulin growth factor binding protein-1, titin and mitochondrial gene 16 S rRNA and two novel genes (function unknown). The down-regulated genes included those encoding RNA polymerase II elongation factor-like protein, NADH dehydrogenase and one novel gene (function unknown). In the present study, we isolated and characterized one of two novel muscle genes that were remarkably up-regulated by spaceflight. The deduced amino acid sequence of the spaceflight-induced gene (sfig) comprises 86 amino acid residues and is well conserved from Drosophila to Homo sapiens. A putative leucine-zipper structure located at the N-terminal region of sfig suggests that this gene may encode a transcription factor. The up-regulated expression of this gene, confirmed by Northern blot analysis, was observed not only in the muscles of spaceflight rats but also in the muscles of tail-suspended rats, especially in the early stage of tail-suspension when gastrocnemius muscle atrophy initiated. The gene was predominantly expressed in the kidney, liver, small intestine and heart. When rat myoblastic L6 cells were grown to 100% confluence in the cell culture system, the expression of sfig was detected regardless of the cell differentiation state. These results suggest that spaceflight has many genetic effects on rat skeletal muscle.

STS-90 Shuttle Project↗