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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Mychonastes desiccatus Brown sp. nova (Chlorococcales, Chlorophyta)--an intertidal alga forming achlorophyllous desiccation-resistant cysts

An intertidal Chlorella-like alga Mychonastes desiccatus Brown sp. nova, capable of forming achlorophyllous desiccation-resistant cysts, has been grown in unialgal culture. This small alga was first isolated from a dried sample of a well-studied microbial mat. The mat, located at North Pond, Laguna Figueroa, San Quintin, Baja California, Mexico, is a vertically-stratified microbial community which forms laminated sediments. Morphology, pigment composition and G+C content are within the range typical for the genus Chlorella s. 1. Unlike other chlorellae, however, upon desiccation M. desiccatus forms an achlorophyllous, lipid-filled cyst (thick-walled resting stage) in which no plastid is evident. Rewetting leads to chloroplast differentiation, excystment and recovery of the fully green alga. During desiccation, sporopollenin is deposited within a thickening cell wall. Encystment cannot be induced by growth in the dark. The formation of desiccation-induced cysts allows the alga to survive frequent and intermittent periods of dryness. These chlorellae tolerate wide ranges of acidity and temperature; they both grow and form cysts in media in which sodium ions are replaced with potassium. Although the cysts tolerate crystalline salts, the cell grow optimally in concentrations corresponding from three-quarters to full-strength seawater.

NASA Discipline Exobiology↗
NASA NTRS1975

Differential permeation of artemia cysts and cucumber seeds by alcohols

The rate of penetration of the simpler alcohols into brine shrimp cysts and cucumber seeds was studied. In solutions below 70% the rate of penetration is related to lipid solvent capacity of the alcohol. In concentrations above 70%, particularly in absolute alcohols, methanol penetrates brine shrimp rapidly and ethanol penetrates slowly. All the other alcohols tested did not penetrate the dormant structures. Ethionine and deuteroxy-methanol did not affect the rate of penetration of methanol. It is suggested that in dehydrated membranes the lipid moiety is protected by a continuous sheet of protein. Methanol, which is fairly similar to water, is probably able to penetrate the membrane by initiating a conformation change in the protein, exposing the lipid which subsequently dissolves in the methanol thus destroying the membrane.

Smith, C. W.↗
NASA NTRS1990

Development of the Statocyst in Aplysia Californica: Observations on Statoconial Development - Part 1

The gravity receptor organs of gastropod molluscs, such as Aplysia californica, are bilateral paired statocysts, which contain dense statoconia within a fluid-filled cyst. Gravitational forces on the statoconia are sensed through their interaction with ciliated mechanoreceptor cells in the wall of the cyst. Larval Aplysia contain a single statolith within each statocyst; when the animals grow to a critical size, they begin producing multiple statoconia, a process that continues throughout life. The number of statoconia is highly correlated with animal weight but poorly correlated with age, indicating that stone production is related to total metabolism. The single statolith has an amorphous internal structure whereas the multiple statoconia have calcification deposited on concentric layers of membrane or matrix protein. The statolith appears to be produced within the cyst lumen but the multiple statoconia are produced within supporting cells between the receptor cells. Large adult animals have statoconia larger than those in early post-metamorphic animals which have just started producing multiple stones. The maximum statocyst diameter at which the receptor-cell cilia can suspend the statolith in the center of the cyst lumen is 45 micrometers; production of multiple stones begins when the cyst reaches this size. The mechanisms by which statoconia production is initiated and controlled are discussed.

Wiederhold, Michael L.↗
NASA NTRS1995

Effect of microgravity and hypergravity on embryo axis alignment during postencystment embryogenesis in Artemia franciscana (Anostraca)

Cysts of brine shrimp attached with a liquid adhesive to 12-mm diameter glass coverslips in a syringe-type fluid processing apparatus were flown aboard the NASA space shuttle Discovery, flight STS-60, from 3-11 February 1994, and were allowed to undergo postencystment embryogenesis and to hatch in microgravity. The shuttle flight and the ground-based control coverslips with attached cysts were parallel to the earth's surface during incubation in salt water. Based on the position of the cyst shell crack in the attached cyst population, the ground-control nauplii emerged mostly upward. On the shuttle in microgravity, although our method of detection of orientation would not reveal emergence toward the coverslip, the ratio of the position of the cyst shell crack in the population after hatching best fit the predicted values of a random direction for nauplii emergence. Centrifugation on earth was then used to create hypergravity forces of up to 73 g during postencystment embryogenesis and hatching. The upward orientation of emerging nauplii showed a high degree of correlation (r(2) =98.8%) with a linear relationship to the log of g, with 78.2% of the total hatching upward at 1 g and 91.0% hatching upward at 73 g.

NASA Program NSCORT↗
NASA NTRS1994

Embryogenesis, hatching and larval development of Artemia during orbital spaceflight

Developmental biology studies, using gastrula-arrested cysts of the brine shrimp Artemia franciscana, were conducted during two flights of the space shuttle Atlantis (missions STS-37 and STS-43) in 1991. Dehydrated cysts were activated, on orbit, by addition of salt water to the cysts, and then development was terminated by the addition of fixative. Development took place in 5 ml syringes, connected by tubing to activation syringes, containing salt water, and termination syringes, containing fixative. Comparison of space results with simultaneous ground control experiments showed that equivalent percentages of naupliar larvae hatched in the syringes (40%). Thus, reactivation of development, completion of embryogenesis, emergence and hatching took place, during spaceflight, without recognizable alteration in numbers of larvae produced. Post-hatching larval development was studied in experiments where development was terminated, by introduction of fixative, 2 days, 4 days, and 8 days after reinitiation of development. During spaceflight, successive larval instars or stages, interrupted by molts, occurred, generating brine shrimp at appropriate larval instars. Naupliar larvae possessed the single naupliar eye, and development of the lateral pair of adult eyes also took place in space. Transmission electron microscopy revealed extensive differentiation, including skeletal muscle and gut endoderm, as well as the eye tissues. These studies demonstrate the potential value of Artemia for developmental biology studies during spa ceflight, and show that extensive degrees of development can take place in this microgravity environment.

Spooner, B. S.↗
NASA NTRS1997

The Structure of the Statocyst of the Freshwater Snail Biomphalaria Glabrata (Pulmonata, Basommatophora)

The structure of the statocyst of the freshwater snail Biomphalaria glabrata has been examined by light and electron microscopy. The two statocysts are located on the dorsal-lateral side of the left and right pedal ganglion. The statocysts are spherical, fluid-filled capsules with a diameter of approximately 60 microns for young and 110 microns for adult snails. The wall of the cyst is composed of large receptor cells and many smaller supporting cells. The receptor cells bear cilia which are evenly distributed on the apical surface. The cilia have the typical 9+2 internal tubule configuration. Striate rootlets originate from the base of the basal body and run downward into the cytoplasm. Side-roots arise from one side of the basal body and a basal foot from the other. For each receptor cell, the basal foot always points to the periphery of the surface, indicating that the receptor cell is non-polarized. The receptor cells contain cytoplasmic organelles such as mitochondria, ribosomes, rough and smooth endoplasmic reticulum, compact Golgi bodies and multivesicular bodies. Supporting cells bearing microvilli are interposed between the receptor cells. The junction complex between the supporting cells and the receptor cells is composed of adherens and septate junctions, while between supporting cells only the adherens junctions are present. The static nerve arises from the lateral side of the cyst and contains axons in which parallel neurotubules and mitochondria are found. The axons arise directly from the base of the receptor cells without synapse. In the cyst lumen there are unattached statoconia. The statoconia have a plate-like or concentric membranous ring structure. Based on the morphology, the function of the statocyst in Biomphalaria is discussed.

Gao, Wenyuan↗
NASA NTRS2001

Model of statoconia accumulation in gravireceptors of mollusks

The kinetics of formation and accumulation of statoconia are different for Aplysia californica and Biomphalaria glabrata. In Aplysia californica, the fast growth of statoconia number occurs after the critical size (approximately 45 micrometers) of statocyst is reached; then the increase of statoconia number is proceeding with the nonmonotonic rate during the life of an animal. In Biomphalaria the growth of statoconia number occurs only in the initial phase. Then long-term evolution of statoconia in the absence of their generation is the result of their growth in the cyst lumen. In the case of Aplysia californica it is not clear whether a temporal change of the statoconia size distribution (SSD) is caused by statoconia growth in the cyst lumen similar to that in Biomphalaria (Model 1) or statoconia growth takes place in supporting cells until their release into the cyst lumen occurs. (Model 2). This problem is of practical importance because the majority of experiments related to the development of molluscan gravireceptors in altered gravity dealt with an initial phase of statoconia evolution in Aplysia californica and Biomphalaria glabrata. The purpose of the present work is the application of mathematical modeling to the analysis of mechanisms of statoconia formation by supporting cells.

Non-NASA Center↗
NASA NTRS1972

Zinc in Entamoeba invadens.

Atomic absorption spectroscopy, electron microprobe analysis, and dithizone staining of trophozoites and cysts of Entamoeba invadens demonstrate that these cells have a high concentration of zinc (approximately one picogram per cell or 1% of their dry weight). In the cysts of this organism, the zinc is confined to the chromatoid bodies, which previous work has shown to contain crystals of ribosomes. The chemical state and function of this zinc are unknown.

Morgan, R. S.↗
NASA NTRS2000

Otoliths developed in microgravity

Little is known about mechanisms that regulate the development of the otoliths in the gravity-sensing organs. Several reported experiments suggest that the growth of the otoliths is adjusted to produce a test mass of the appropriate weight. If this is the case, larger than normal otoliths would be expected in animals reared in reduced gravity and a reduced mass, relative to 1-g controls, would be expected in animals reared at elevated g. In gastropod mollusks, the gravity-sensing organ is the statocyst, a spherical organ whose wall is made largely of sensory receptor cells with motile cilia facing the lumen. Dense statoconia in the cyst lumen interact with cilia of receptor cells at the bottom of the cyst and action potentials in their axons carry information on direction and magnitude of gravity and linear acceleration. In the marine mollusk, Aplysia californica, larvae reared at 2 to 5-g, the volume of statoconia was reduced in a graded manner, compared to 1-g control animals. In the statocyst of the fresh-water pond snail, Biomphalaria glabrata, reared in space in the Closed Equilibrated Biological Aquatic System (CEBAS), the number and total volume of statoconia was increased approximately 50%, relative to ground-reared controls. Lychakov found the utricular otolith to be 30% larger in space-reared Xenopus, whereas we found the saccular otolith to be significantly larger in newt larvae reared in space. In cichlid fish reared on a centrifuge, the saccular otolith was smaller than in 1-g controls. Here, we demonstrate that the otoliths of late-stage embryos of the swordtail fish, Xiphophorus helleri, reared in space on STS-89 and STS-90 (Neurolab) were significantly larger than those of ground-controls reared in functionally identical hardware.

short duration↗
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 NTRS1992

Brine shrimp development in space: ground-based data to shuttle flight results

The brine shrimp, Artemia salina, has been used as a model system to assess microgravity effects on developing organisms. Following fertilization and early development, the egg can arrest in early gastrula as a dehydrated cyst stage that is stable to harsh environments over long time periods. When salt water is added, the cysts can reactivate, with embryonic development and egg hatching occurring in about 24 h. A series of larval molts or instars, over about a 2 week period, results in the adult crustacean. We have assessed these developmental events in a closed syringe system, a bioprocessing module, in ground-based studies, and have conducted preliminary in-orbit experiments aboard the Space Shuttle Atlantis during the flights of STS-37 and STS-43. Although the in-flight data are limited, spectacular degrees of development have been achieved.

NASA Discipline Number 93-10↗
NASA NTRS1976

Effects of high-LET particles /A-40/ on the brain of Drosophila melanogaster

To investigate the effects of galactic heavy particles on nervous tissue, Drosophila melanogaster flies were exposed to A-40 from the Super-HILAC accelerator at the Lawrence Berkeley Laboratory. The energy of the particles reaching the Drosophila neurons was 4.8 MeV/nucleon, and the fluence ranged from 60,000 to 80 million particles/sq cm. Thirty-five days after irradiation at the higher fluences, extensive tissue fragmentation and cysts were found. At fluences as low as one hit/two cell bodies (about 5 million) and one hit/90 cell bodies (about 90,000 particles/sq cm or 21 rad average dose) swelling of neuronal cytoplasm and focally fragmented membranes were noted; at fluences ranging from one hit/six to one hit/135 cell bodies, there was frequently a marked increase in glial lamellae around nerve-cell processes, which often had degenerative features. These findings support the view that single hits by heavy particles may injure nervous tissue.

Miquel, J.↗
NASA NTRS1981

General description and operation of the agro-environmental system: Crop management modeling

Input for a data management system to provide farmers with information to improve crop management practices in Virginia requires monitoring of control crops at field stations, crop surveys derived from remotely sensed aircraft data, meteorological data from synchronous satellites, and details of local agricultural conditions. Presently models are under development for determining pest problems, water balance in the soil, stages of plant maturity, and optimum planting date. The status of the Cerospora leafspot model for peanut crop management is considered. Other models under development planned relate to Cylindtocladium Blackrot and Sclerotinia blight of peanuts, cyst nematode (Globerdena solanacearum) of tobacco, and red crown rot of soybeans. A software for program for estimating precipitation and solar radiation on a statewise basis is also being developed.

Gross, E.↗
NASA NTRS1991

First biological and dosimetric results of the free flyer biostack experiment AO015 on LDEF

The main objectives of the Biostack Experiment are to study the effectiveness of the structured components of the cosmic radiation to bacterial spores, plant seeds, and animal cysts for a long duration spaceflight and to get dosimetric data such as particle fluences and spectra and total doses for the Long Duration Exposure Facility orbit. The configuration of the experiment packages allows the localization of the trajectory of the particles in each biological layer and to correlate the potential biological impairment or injury with the physical characteristics of the responsible particle. Although the Biostack Experiment was designed for a long duration flight of only nine months, most of the biological systems show a high hatching or germination rate. Some of the first observations are an increase of the mutation rate of embryonic lethals in the second generation of Arabidopsis seeds, somatic mutations, and a reduction of growth rates of corn plants and a reduction of life span of Artemia salina shrimps. The different passive detector systems are also in a good shape and give access to a proper dosimetric analysis. The results are summarized, and some aspects of future analysis are shown.

Reitz, G.↗
NASA NTRS1997

Development of the Statocyst in the Freshwater Snail Biomphalaria Glabrata (Pulmonata, Basommatophora)

The development of the statocyst of the freshwater snail Biomphalaria glabrata has been examined from embryo to adult. Special emphasis was put on the growth of the statoconia in the statocysts. In the statocysts of embryonic snails (90-120 h after oviposition) there is not a single statolith but an average of 40-50 statoconia per statocyst. The number of statoconia increases to 385-400 when the snails reach a shell diameter of 4 mm and remains relatively constant thereafter, irrespective of shell size. Small statoconia are found in supporting cells, which suggests that the statoconia are produced within these cells. The average diameter of statoconia and the total mass of statoconia increase with increasing shell diameter. The average number of large statoconia (diameter greater than 7 micrometers) per statocyst continues to increase from 2 to 10 mm animals while the number of small ones (diameter less than 4 micrometers) initially rises and then decreases after 4 mm. These results demonstrate continuous growth of the statoconia in the cyst lumen of Biomphalaria. The single statoconia vibrate in a regular pattern in vivo, indicating beating of the statocyst cilia. The statoconia sink under the influence of gravity to load and stimulate receptor cells which are at the bottom. The length of cilia and the size of statocyst gradually increase as the animal grows. However, the increase in the volume of the statocyst is relatively small compared with the increase in body weight during normal development.

Gao, Wenyuan↗
NASA NTRS1997

Automated Analysis Workstation

Information from NASA Tech Briefs of work done at Langley Research Center and the Jet Propulsion Laboratory assisted DiaSys Corporation in manufacturing their first product, the R/S 2000. Since then, the R/S 2000 and R/S 2003 have followed. Recently, DiaSys released their fourth workstation, the FE-2, which automates the process of making and manipulating wet-mount preparation of fecal concentrates. The time needed to read the sample is decreased, permitting technologists to rapidly spot parasites, ova and cysts, sometimes carried in the lower intestinal tract of humans and animals. Employing the FE-2 is non-invasive, can be performed on an out-patient basis, and quickly provides confirmatory results.

Source record↗
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↗