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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Gravity and animal embryos

Out of more than 4,500 rat hours in space there was only one experimental attempt (Cosmos 1129) at mating with an apparent absence of fertilization, implantation and subsequent development to term and partuition. Portions of this process were successfully flown, however, including the major portion of organogenesis in the rat (Cosmos 1524). These observations show that the cellular and molecular events underlying morphogenesis and differentiation in a small mammal can proceed normally in-utero under microgravity and other conditions encountered during short-duration flight. However, it is not known whether this situation will hold for larger mammals over several generations during extended missions that venture outside of near Earth. Furthermore, it is not understood why the previous attempt at obtaining copulation, fertilization and implantation in orbit failed but may be related to limitations of the rat habitat for meeting the preconditions for reproductive behavior. With respect to mammalian development it is important to appreciate that fertilization and development occur internally within the female and take a long time to complete and their success will, therefore, be contingent upon the maternal response to the space environment. One process central to development (the establishment of cell lines) is initiated prior to implantation by environmental asymmetries preceived by progenitor cells. These asymmetries appear to result from the formation of asymmetric cell-cell contacts and the concommitant development of an electrical axis across the progenitor cells. Other asymmetries were also documented. It is not known whether any of the known asymmetries perceived by progenitor cells are influenced by gravity vectors and/or by the maternal response to microgravity and other conditions encountered in space.

Wiley, Lynn M.↗
NASA NTRS1992

Localization of extracellular matrix components in developing mouse salivary glands by confocal microscopy

The importance of the extracellular matrix (ECM) in epithelial-mesenchymal interactions in developing organisms is well established. Proteoglycans and interstitial collagens are required for the growth, morphogenesis, and differentiation of epithelial organs and the distribution of these molecules has been described. However, much less is known about other ECM macromolecules in developing epithelial organs. We used confocal microscopy to examine the distribution of laminin, heparan sulfate (BM-1) proteoglycan, fibronectin, and collagen types I, IV, and V, in mouse embryonic salivary glands. Organ rudiments were isolated from gestational day 13 mouse embryos and cultured for 24, 48, or 72 hours. Whole mounts were stained by indirect immunofluorescence and then examined using a Zeiss Laser Scan Microscope. We found that each ECM component examined had a distinct distribution and that the distribution of some molecules varied with culture time. Laminin was mainly restricted to the basement membrane. BM-1 proteoglycan was concentrated in the basement membrane and also formed a fine network throughout the mesenchyme. Type IV collagen was mainly located in the basement membrane of the epithelium, but it was also present throughout the mesenchyme. Type V collagen was distributed throughout the mesenchyme at 24 hours, but at 48 hours was principally located in the basement membrane. Type I collagen was distributed throughout the mesenchyme at all culture times, and accumulated in the clefts and particularly at the epithelial-mesenchymal interface as time in culture increased. Fibronectin was observed throughout the mesenchyme at all times.

Hardman, P.↗
NASA NTRS1998

The Isothermal Dendritic Growth Experiment

The growth of dendrites is one of the commonly observed forms of solidification encountered when metals and alloys freeze under low thermal gradients, as occurs in most casting and welding processes. In engineering alloys, the details of the dendritic morphology directly relates to important material responses and properties. Of more generic interest, dendritic growth is also an archetypical problem in morphogenesis, where a complex pattern evolves from simple starting conditions. Thus, the physical understanding and mathematical description of how dendritic patterns emerge during the growth process are of interest to both scientists and engineers. The Isothermal Dendritic Growth Experiment (IDGE) is a basic science experiment designed to measure, for a fundamental test of theory, the kinetics and morphology of dendritic growth without complications induced by gravity-driven convection. The IDGE, a collaboration between Rensselaer Polytechnic Institute, in Troy NY, and NASA's Lewis Research Center (LeRC) was developed over a ten year period from a ground-based research program into a space flight experiment. Important to the success of this flight experiment was provision of in situ near-real-time teleoperations during the spaceflight experiment.

Glicksman, M. E.↗
NASA NTRS1996

Cellular Basis of Mechanotransduction

Physical forces, such as those due to gravity are fundamental regulators of tissue development. To influence morphogenesis, mechanical forces must alter growth and function. Yet little is known about how cells convert mechanical signals into a chemical response. This presentation attempts to place the potential molecular mediators of mechanotransduction within the context of the structural complexity of living cells.

Ingber, Donald E.↗
NASA NTRS1997

Fossilization of Coniform (Phormidium) Stromatolites In Siliceous Thermal Springs, Yellowstone National Park

We have studied fossilization processes in well-developed cyanobacterial mats present in mid-terrace ponds of silica-precipitating thermal springs of Yellowstone National Park. These mats occur over temperatures of approx.35-60 C and are dominated by species of Phormidium. Within Bonded systems two end member environments have been distinguished based temperature, depth, and the stability of spring inflows, each differing substantially in the style of stromatolite morphogenesis and fossilization. Type 1 systems include shallow, ephemeral ponds where water flow and temperature fluctuates widely on a seasonal basis; mats typically secrete rapidly up to the air-water interface, forming exposed islands. Silicification occurs primarily by the wicking of water onto the surface of exposed mats, leading to the evaporative concentration of silica near the surface. pH microelectronic measurements in partially-exposed columns show strong gradients in pH with values exceeding 10.5 in the upper am of silicifying mats, decreasing to <9.0 a few mm below the surface. High oxygen concentrations lead to the rapid oxidation of most organic materials. In Type I systems, the tops of coniform and columnar stromatolites become silicified first, followed by the bases. This typically leads to extensive fragmentation during the initial stages of burial. Case 2 systems include deeper ponds where the water flow, temperature and depth are seasonally more stable, and where mats develop larger-scale tufts and columns. Alkalinity in permanently submerged mats increases into tuft interiors from approx.9.0 near the surface to >10.0 at depth. Moderate silicification is apparent throughout mat frameworks, although there is frequently a densely silicified core near the base. In Type 2 systems, preservation of the coniform and columnar architecture of stromatoilites is much more robust. Sub-fossil examples suggest minimal fragmentation prior to burial. Comparative rapid analysis of the phone zones of submerged and exposed (silicifying) mats demonstrated the recovery of comparable levels of esterified fatty acids in both types of mats. Membrane lipids apparently remain intact during the early stages of silicification, although their fate during early diagenesis is still being evaluated.

Farmer, Jack↗
NASA NTRS2002

Cyanobacterial Community Structure In Lithifying Mats of A Yellowstone Hotspring-Implications for Precambrian Stromatolite Biocomplexity

Denaturing Gradient Gel Electrophoresis (DGGE) of partial 16S rRNA gene sequences was used to investigate the molecular biodiversity of cyanobacterial communities inhabiting various lithified morpho-structures in two hotsprings of Yellowstone National Park. These morpho-structures - flat-topped columns, columnar cones, and ridged cones - resemble ancient stromatolites, which are possibly biogenic in origin. The top, middle and bottom sections of these lithified morpho-structures, as well as surrounding non-lithified mats were analyzed to determine the vertical and spatial distribution of cyanobacterial communities. Results from DGGE indicate that the cyanobacterial community composition of lithified morpho-structures (flat-topped columns, columnar cones, and ridged cones) were largely similar in vertical distribution as well as among the morpho-structures being studied. Preliminary results indicate that the cyanobacterial communities in these lithified morpho-structures were significantly different from communities in surrounding non-lithified mats. These results provide additional support to the theory that certain Phormidium/Leptolyngbya species are involved in the morphogenesis of lithifying morpho-structures in hotsprings and may have played a role in the formation of ancient stromatolites.

Lau, Evan↗
NASA NTRS2003

Bioconvection in Cultures of the Calcifying Unicellular Alga Pleurochrysis Carterae

The unicellular, marine, calcifying alga P leurochiysis carterae--a model to study cell morphogenesis, cell polarity, calcification, gravitaxis, reproduction and development-- has extremely flexible culture requirements. Support studies for a flight experiment addressing cell motility suggested that cell density (cells/ml) affects cell movement in P. carterae cultures through the gradual establishment of bioconvection as the culture grows. To assess the effect of cell density on direction of the movement, without the effects of aging of the culture, swimming behavior was analyzed in aliquots from a series of dilutions obtained from a stock culture. Results showed that at low concentrations cells swim randomly. As the concentration increases, upswimming patterns overtake random swimming. Gradually, up and down movement patterns prevail, representative of bioconvection. This oriented swimming of P. carterae occurs in a wide range of concentrations, adding to the list of flexible requirements, in this case, cell concentration, to be used for spaceflight studies addressing cell motility and bioconvection in a unicellular model of biologically directed mineralization.

Montufar-Solis, Dina↗
NASA NTRS2003

Expression and function of FGF10 in mammalian inner ear development

We have investigated the expression of FGF10 during ear development and the effect of an FGF10 null mutation on ear development. Our in situ hybridization data reveal expression of FGF10 in all three canal crista sensory epithelia and the cochlea anlage as well as all sensory neurons at embryonic day 11.5 (E11.5). Older embryos (E18.5) displayed strong graded expression in all sensory epithelia. FGF10 null mutants show complete agenesis of the posterior canal crista and the posterior canal. The posterior canal sensory neurons form initially and project rather normally by E11.5, but they disappear within 2 days. FGF10 null mutants have no posterior canal system at E18.5. In addition, these mutants have deformations of the anterior and horizontal cristae, reduced formation of the anterior and horizontal canals, as well as altered position of the remaining sensory epithelia with respect to the utricle. Hair cells form but some have defects in their cilia formation. No defects were detected in the organ of Corti at the cellular level. Together these data suggest that FGF10 plays a major role in ear morphogenesis. Most of these data are consistent with earlier findings on a null mutation in FGFR2b, one of FGF10's main receptors. Copyright 2003 Wiley-Liss, Inc.

NASA Discipline Developmental Biology↗
NASA NTRS2003

Polycystins 1 and 2 mediate mechanosensation in the primary cilium of kidney cells

Several proteins implicated in the pathogenesis of polycystic kidney disease (PKD) localize to cilia. Furthermore, cilia are malformed in mice with PKD with mutations in TgN737Rpw (encoding polaris). It is not known, however, whether ciliary dysfunction occurs or is relevant to cyst formation in PKD. Here, we show that polycystin-1 (PC1) and polycystin-2 (PC2), proteins respectively encoded by Pkd1 and Pkd2, mouse orthologs of genes mutated in human autosomal dominant PKD, co-distribute in the primary cilia of kidney epithelium. Cells isolated from transgenic mice that lack functional PC1 formed cilia but did not increase Ca(2+) influx in response to physiological fluid flow. Blocking antibodies directed against PC2 similarly abolished the flow response in wild-type cells as did inhibitors of the ryanodine receptor, whereas inhibitors of G-proteins, phospholipase C and InsP(3) receptors had no effect. These data suggest that PC1 and PC2 contribute to fluid-flow sensation by the primary cilium in renal epithelium and that they both function in the same mechanotransduction pathway. Loss or dysfunction of PC1 or PC2 may therefore lead to PKD owing to the inability of cells to sense mechanical cues that normally regulate tissue morphogenesis.

Non-NASA Center↗
NASA NTRS2002

Directional control of lamellipodia extension by constraining cell shape and orienting cell tractional forces

Directed cell migration is critical for tissue morphogenesis and wound healing, but the mechanism of directional control is poorly understood. Here we show that the direction in which cells extend their leading edge can be controlled by constraining cell shape using micrometer-sized extracellular matrix (ECM) islands. When cultured on square ECM islands in the presence of motility factors, cells preferentially extended lamellipodia, filopodia, and microspikes from their corners. Square cells reoriented their stress fibers and focal adhesions so that tractional forces were concentrated in these corner regions. When cell tension was dissipated, lamellipodia extension ceased. Mechanical interactions between cells and ECM that modulate cytoskeletal tension may therefore play a key role in the control of directional cell motility.

NASA Discipline Cell Biology↗
NASA NTRS2001

Evolution and development of the vertebrate ear

This review outlines major aspects of development and evolution of the ear, specifically addressing issues of cell fate commitment and the emerging molecular governance of these decisions. Available data support the notion of homology of subsets of mechanosensors across phyla (proprioreceptive mechanosensory neurons in insects, hair cells in vertebrates). It is argued that this conservation is primarily related to the specific transducing environment needed to achieve mechanosensation. Achieving this requires highly conserved transcription factors that regulate the expression of the relevant structural genes for mechanosensory transduction. While conserved at the level of some cell fate assignment genes (atonal and its mammalian homologue), the ear has also radically reorganized its development by implementing genes used for cell fate assignment in other parts of the developing nervous systems (e.g., neurogenin 1) and by evolving novel sets of genes specifically associated with the novel formation of sensory neurons that contact hair cells (neurotrophins and their receptors). Numerous genes have been identified that regulate morphogenesis, but there is only one common feature that emerges at the moment: the ear appears to have co-opted genes from a large variety of other parts of the developing body (forebrain, limbs, kidneys) and establishes, in combination with existing transcription factors, an environment in which those genes govern novel, ear-related morphogenetic aspects. The ear thus represents a unique mix of highly conserved developmental elements combined with co-opted and newly evolved developmental elements.

Review↗
NASA NTRS1993

Preliminary observations on the effects of selenate on the development of the embryonic skate, Raja eglanteria

Morphogenesis of the clearnose skate, Raja eglanteria, was not significantly inhibited as a result of 7 days of exposure to 1-2 mM selenate in the sea water during Days 59-69 of embryonic development (hatching would normally have occurred at 82 +/- 4 days of incubation). Although corneal transparency appeared normal in the eye, preliminary measurements of the thickness of Bowman's layer of the cornea suggested that it was significantly thinner in the corneas of embryos exposed to 1-2 mM selenate. Selenate is an ion reported to inhibit sulfation of glycosaminoglycans in connective tissue.

NASA Discipline Number 93-10↗
NASA NTRS1992

Scanning electron microscope observations of brine shrimp larvae from space shuttle experiments

Brine shrimp are encysted as gastrula stage embryos, and may remain dehydrated and encysted for years without compromising their viability. This aspect of brine shrimp biology is desirable for studying development of animals during space shuttle flight, as cysts placed aboard a spacecraft may be rehydrated at the convenience of an astronaut, guaranteeing that subsequent brine shrimp development occurs only on orbit and not on the pad during launch delays. Brine shrimp cysts placed in 5 ml syringes were rehydrated with salt water and hatched during a 9 day space shuttle mission. Subsequent larvae developed to the 8th larval stage in the sealed syringes. We studied the morphogenesis of the brine shrimp larvae and found the larvae from the space shuttle experiments similar in rate of growth and extent of development, to larvae grown in sealed syringes on the ground. Extensive differentiation and development of embryos and larvae can occur in a microgravity environment.

short duration↗
NASA NTRS1987

Plants in space

Space may be, as some have called it, our last frontier. As such, it provides novel, even unique research opportunities. Plants are sure to figure significantly in these activities. The ability to manipulate the force of gravity from near zero to 1 g affords fresh opportunities to investigate gravity's physiological effects as well as a means of probing gravi- and phototropism, thigmo-morphogenesis, and other environmental effects in a state uncompromised by gravity. In this review we aim primarily to consider phenomenology, a goal that befits the state of our knowledge from space experiments. We intend to provide grist for future ground-based and space experiments and to reveal the potential for scientific discovery in this area.

long duration↗
NASA NTRS1992

Endochondral bone formation in embryonic mouse pre-metatarsals

Long term exposure to a reduced gravitational environment has a deleterious effect on bone. The developmental events which occur prior to initial bone deposition will provide insight into the regulation of mature bone physiology. We have characterized a system in which the events preceding bone formation take place in an isolated in vitro organ culture environment. We show that cultured pre-metatarsal tissue parallels development of pre-metatarsal tissue in the embryo. Both undergo mesenchyme differentiation and morphogenesis to form a cartilage rod, which resembles the future bone, followed by terminal chondrocyte differentiation in a definite morphogenetic pattern. These sequential steps occur prior to osteoblast maturation and bone matrix deposition in the developing organism. Alkaline phosphatase (ALP) activity is a distinctive enzymatic marker for mineralizing tissues. We have measured this activity throughout pre-metatarsal development and show (a) where in the tissue it is predominantly found, and (b) that this is indeed the mineralizing isoform of the enzyme.

NASA Discipline Number 93-10↗
NASA NTRS1993

Preliminary observations on the effects of selenate on the development of the embryonic skate, Raja eglanteria

Morphogenesis of the clearnose skate, Raja eglanteria, was not significantly inhibited as a result of 7 days of exposure to 1-2 mM selenate in the sea water during Days 59-69 of embryonic development (hatching would normally have occurred at 82 +/- 4 days of incubation). Although corneal transparency appeared normal in the eye, preliminary measurements of the thickness of Bowman's layer of the cornea suggested that it was significantly thinner in the corneas of embryos exposed to 1-2 mM selenate. Selenate is an ion reported to inhibit sulfation of glycosaminoglycans in connective tissue.

Non-NASA Center↗
NASA NTRS1990

Polyamines in plant physiology

The diamine putrescine, the triamine spermidine, and the tetramine spermine are ubiquitous in plant cells, while other polyamines are of more limited occurrence. Their chemistry and pathways of biosynthesis and metabolism are well characterized. They occur in the free form as cations, but are often conjugated to small molecules like phenolic acids and also to various macromolecules. Their titer varies from approximately micromolar to more than millimolar, and depends greatly on environmental conditions, especially stress. In cereals, the activity of one of the major polyamine biosynthetic enzymes, arginine decarboxylase, is rapidly and dramatically increased by almost every studied external stress, leading to 50-fold or greater increases in putrescine titer within a few hours. The physiological significance of this increase is not yet clear, although most recent work suggests an adaptive, protective role. Polyamines produced through the action of ornithine decarboxylase, by contrast, seem essential for DNA replication and cell division. The application of exogenous polyamines produces effects on patterns of senescence and morphogenesis, suggesting but not proving a regulatory role for polyamines in these processes. The evidence for such a regulatory role is growing.

Review↗
NASA NTRS2001

Analysis of the myosins encoded in the recently completed Arabidopsis thaliana genome sequence

BACKGROUND: Three types of molecular motors play an important role in the organization, dynamics and transport processes associated with the cytoskeleton. The myosin family of molecular motors move cargo on actin filaments, whereas kinesin and dynein motors move cargo along microtubules. These motors have been highly characterized in non-plant systems and information is becoming available about plant motors. The actin cytoskeleton in plants has been shown to be involved in processes such as transportation, signaling, cell division, cytoplasmic streaming and morphogenesis. The role of myosin in these processes has been established in a few cases but many questions remain to be answered about the number, types and roles of myosins in plants. RESULTS: Using the motor domain of an Arabidopsis myosin we identified 17 myosin sequences in the Arabidopsis genome. Phylogenetic analysis of the Arabidopsis myosins with non-plant and plant myosins revealed that all the Arabidopsis myosins and other plant myosins fall into two groups - class VIII and class XI. These groups contain exclusively plant or algal myosins with no animal or fungal myosins. Exon/intron data suggest that the myosins are highly conserved and that some may be a result of gene duplication. CONCLUSIONS: Plant myosins are unlike myosins from any other organisms except algae. As a percentage of the total gene number, the number of myosins is small overall in Arabidopsis compared with the other sequenced eukaryotic genomes. There are, however, a large number of class XI myosins. The function of each myosin has yet to be determined.

NASA Discipline Plant Biology↗