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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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NASA NTRS1990

Revival of Dobell's "chromidia" hypothesis: chromatin bodies in the amoebomastigote Paratetramitus jugosus

Multiple fission of a mature Paratetramitus jugosus (approx. 10 micrometers long) resulted in the production of many small, roughly spherical (2-7 micrometers in diameter) amoebae. Our observation of live material and examination of over two hundred micrographs lead us to suggest that DNA-containing membrane-bounded chromatin bodies bud amitotically from the nucleus. DAPI-stained bodies of these were observed in the cytoplasm of amoebae, mastigotes, and cysts, and at least some of these chromatin bodies seemed to be released into the medium. This interpretation revives for P. jugosus the "chromatin hypothesis" of Dobell. Our data, consistent with the descriptions of Dobell, Hogue, and Wherry, indicate that encysting amoebae may reproduce by chromidia. Dobell's original chromidia concept was limited to amoebae. Others claimed for it far-reaching consequences: "chromidia" were touted as an explanation for embryogenesis and histogenesis of metazoa. Although there is no evidence for chromidia in animals, outright rejection of Dobell's chromidia hypothesis sensu stricto as an amitotic multiple fission process in amoebae is unjustified.

Non-NASA Center↗

NASA NTRS2003

Three-Dimensional Engineered High Fidelity Normal Human Lung Tissue-Like Assemblies (TLA) as Targets for Human Respiratory Virus Infections

Unlike traditional two-dimensional (2D) cell cultures, three-dimensional (3D) tissue-like assemblies (TLA) (Goodwin et aI, 1992, 1993, 2000 and Nickerson et aI. , 2001,2002) offer high organ fidelity with the potential to emulate the infective dynamics of viruses and bacteria in vivo. Thus, utilizing NASA micro gravity Rotating Wall Vessel (RWV) technology, in vitro human broncho-epithelial (HBE) TLAs were engineered to mimic in vivo tissue for study of human respiratory viruses. These 3D HBE TLAs were propagated from a human broncho-tracheal cell line with a mesenchymal component (HBTC) as the foundation matrix and either an adult human broncho-epithelial cell (BEAS-2B) or human neonatal epithelial cell (16HBE140-) as the overlying element. Resulting TLAs share several characteristic features with in vivo human respiratory epithelium including tight junctions, desmosomes and cilia (SEM, TEM). The presence of epithelium and specific lung epithelium markers furthers the contention that these HBE cells differentiate into TLAs paralleling in vivo tissues. A time course of infection of these 3D HBE TLAs with human respiratory syncytial virus (hRSV) wild type A2 strain, indicates that virus replication and virus budding are supported and manifested by increasing virus titer and detection of membrane-bound F and G glycoproteins. Infected 3D HBE TLAs remain intact for up to 12 days compared to infected 2D cultures that are destroyed in 2-3 days. Infected cells show an increased vacuolation and cellular destruction (by transmission electron microscopy) by day 9; whereas, uninfected cells remain robust and morphologically intact. Therefore, the 3D HBE TLAs mimic aspects of human respiratory epithelium providing a unique opportunity to analyze, for the first time, simulated in vivo viral infection independent of host immune response.

Goodwin, T. J.↗

NASA NTRS1972

Plant Adaptation to Cold. 1: Chlorophyll. 2: Minerals

A number of montane herbs in northern Utah typically form flower buds beneath the snow cover and flower either through it or immediately after its recession. Two of these species, one naturally occurring, Claytonia lanceolata, and one cultivated bulb, Galanthus nivalis, were investigated for their response to this stress environment. Snow depth patterns, chlorophyll content of tissues, and plants grown in light-tight boxes, suggest that light passing through the snow to reach plants growing underneath is not critically involved in the timing of their developmental cycles or in their ability to endure this low temperature environment. Ability to endure stress seems to be closely related in a number of ways to activity at the plant membranes. Plants were protected from low temperature damage by application of cytokinin or calcium, both of which probably acted at the membrane. Potassium calcium antagonisms were reflected in the internal distribution of the ions under natural stress conditions; and plants that differentiated at the meristem while growing through the snow accumulated calcium at the tip during this growth.

Rosen, P.↗