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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 595 records · Page 33
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Worldwide Population Genomics Reveal Long-Term Stability of the Mitochondrial Genome Architecture in a Keystone Marine Plant

Mitochondrial genomes (mitogenomes) of flowering plants are composed of multiple chromosomes. Recombination within and between the mitochondrial chromosomes may generate diverse DNA molecules termed isoforms. The isoform copy number and composition can be dynamic within and among individual plants due to uneven replication and homologous recombination. Nonetheless, despite their functional importance, the level of mitogenome conservation within species remains understudied. Whether the ontogenetic variation translates to evolution of mitogenome composition over generations is currently unknown. Here we show that the mitogenome composition of the seagrass Zostera marina is conserved among worldwide populations that diverged ca. 350,000 years ago. Using long-read sequencing, we characterized the Z. marina mitochondrial genome and inferred the repertoire of recombination-induced configurations. To characterize the mitochondrial genome architecture worldwide and study its evolution, we examined the mitogenome in Z. marina meristematic region sampled in 16 populations from the Pacific and Atlantic oceans. Our results reveal a striking similarity in the isoform relative copy number, indicating a high conservation of the mitogenome composition among distantly related populations and within the plant germline, despite a notable variability during individual ontogenesis. Our study supplies a link between observations of dynamic mitogenomes at the level of plant individuals and long-term mitochondrial evolution.

(sub)stoichiometric shifting↗
DOE OSTI2025

Turbo‐charging crop improvement: harnessing multiplex editing for polygenic trait engineering and beyond

Multiplex CRISPR editing has emerged as a transformative platform for plant genome engineering, enabling the simultaneous targeting of multiple genes, regulatory elements, or chromosomal regions. This approach is effective for dissecting gene family functions, addressing genetic redundancy, engineering polygenic traits, and accelerating trait stacking and de novo domestication. Its applications now extend beyond standard gene knockouts to include epigenetic and transcriptional regulation, chromosomal engineering, and transgene‐free editing. These capabilities are advancing crop improvement not only in annual species but also in more complex systems such as polyploids, undomesticated wild relatives, and species with long generation times. At the same time, multiplex editing presents technical challenges, including complex construct design and the need for robust, scalable mutation detection. We discuss current toolkits and recent innovations in vector architecture, such as promoter and scaffold engineering, that streamline workflows and enhance editing efficiency. High‐throughput sequencing technologies, including long‐read platforms, are improving the resolution of complex editing outcomes such as structural rearrangements—often missed by standard genotyping—when targeting repetitive or tandemly spaced loci. To fully realize the potential of multiplex genome engineering, there is growing demand for user‐friendly, synthetic biology‐compatible, and scalable computational workflows for gRNA design, construct assembly, and mutation analysis. Experimentally validated inducible or tissue‐specific promoters are also highly desirable for achieving spatiotemporal control. As these tools continue to evolve, multiplex CRISPR editing is poised to become a foundational technology of next‐generation crop improvement to address challenges in agriculture, sustainability, and climate resilience.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Engineered Escherichia coli platforms for tyrosine-derivative production from phenylalanine using phenylalanine hydroxylase and tetrahydrobiopterin-regeneration system

Aromatic compounds derived from tyrosine are important and diverse chemicals that have industrial and commercial applications. Although these aromatic compounds can be obtained by extraction from natural producers, their growth is slow, and their content is low. To overcome these problems, many of them have been chemically synthesized from petroleum-based feedstocks. However, because of the environmental burden and depleting availability of feedstock, microbial cell factories are attracting much attention as sustainable and environmentally friendly processes. To facilitate development of microbial cell factories for producing tyrosine derivatives, we developed simple and convenient tyrosine-producing Escherichia coli platforms with a bacterial phenylalanine hydroxylase, which converted phenylalanine to tyrosine with tetrahydromonapterin as a cofactor, using a synthetic biology approach. By introducing a tetrahydrobiopterin-regeneration system, the tyrosine titer of the plasmid-based engineered strain was 4.63 g/L in a medium supplemented with 5.00 g/L phenylalanine with a test tube. The strains were successfully used to produce industrially attractive compounds, such as tyrosol with a yield of 1.58 g/L by installing a tyrosol-producing module consisting of genes encoding tyrosine decarboxylase and tyramine oxidase on a plasmid. Gene integration into E. coli chromosomes has an advantage over the use of plasmids because it increases genetic stability without antibiotic feeding to the culture media and enables more flexible pathway engineering by accepting more plasmids with artificial pathway genes. Therefore, we constructed a plasmid-free tyrosine-producing platform by integrating five modules, comprising genes encoding the phenylalanine hydroxylase and tetrahydrobiopterin-regeneration system, into the chromosome. The platform strain could produce 1.04 g/L of 3,4-dihydroxyphenylalanine, a drug medicine, by installing a gene encoding tyrosine hydroxylase and the tetrahydrobiopterin-regeneration system on a plasmid. Moreover, by installing the tyrosol-producing module, tyrosol was produced with a yield of 1.28 g/L. We developed novel E. coli platforms for producing tyrosine from phenylalanine at multi-gram-per-liter levels in test-tube cultivation. The platforms allowed development and evaluation of microbial cell factories installing various designed tyrosine-derivative biosynthetic pathways at multi-grams-per-liter levels in test tubes.

09 BIOMASS FUELS↗
DOE OSTI2023

Conservation and Expansion of Transcriptional Factor Repertoire in the Fusarium oxysporum Species Complex

The Fusarium oxysporum species complex (FOSC) includes both plant and human pathogens that cause devastating plant vascular wilt diseases and threaten public health. Each F. oxysporum genome comprises core chromosomes (CCs) for housekeeping functions and accessory chromosomes (ACs) that contribute to host-specific adaptation. This study inspects global transcription factor profiles (TFomes) and their potential roles in coordinating CC and AC functions to accomplish host-specific interactions. Remarkably, we found a clear positive correlation between the sizes of TFomes and the proteomes of an organism. With the acquisition of ACs, the FOSC TFomes were larger than the other fungal genomes included in this study. Among a total of 48 classified TF families, 14 families involved in transcription/translation regulations and cell cycle controls were highly conserved. Among the 30 FOSC expanded families, Zn2-C6 and Znf_C2H2 were most significantly expanded to 671 and 167 genes per family including well-characterized homologs of Ftf1 (Zn2-C6) and PacC (Znf_C2H2) that are involved in host-specific interactions. Manual curation of characterized TFs increased the TFome repertoires by 3% including a disordered protein Ren1. RNA-Seq revealed a steady pattern of expression for conserved TF families and specific activation for AC TFs. Functional characterization of these TFs could enhance our understanding of transcriptional regulation involved in FOSC cross-kingdom interactions, disentangle species-specific adaptation, and identify targets to combat diverse diseases caused by this group of fungal pathogens.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Paludibacter propionicigenes type strain (WB4 T )

Paludibacter propionicigenes Ueki et al. 2006 is the type species of the genus Paludibacter, which belongs to the family Porphyromonadaceae. The species is of interest because of the position it occupies in the tree of life where it can be found in close proximity to members of the genus Dysgonomonas. This is the first completed genome sequence of a member of the genus Paludibacter and the third sequence from the family Porphyromonadaceae. The 3,685,504 bp long genome with its 3,054 protein-coding and 64 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Isosphaera pallida type strain (IS1B T )

Isosphaera pallida (ex Woronichin 1927) Giovannoni et al. 1995 is the type species of the genus Isosphaera. The species is of interest because it was the first heterotrophic bacterium known to be phototactic, and it occupies an isolated phylogenetic position within the Planctomycetaceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. This is the first complete genome sequence of a member of the genus Isosphaera and the third of a member of the family Planctomycetaceae. The 5,472,964 bp long chromosome and the 56,340 bp long plasmid with a total of 3,763 protein-coding and 60 RNA genes are part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Cellulophaga algicola type strain (IC166 T )

Cellulophaga algicola Bowman 2000 belongs to the family Flavobacteriaceae within the phylum 'Bacteroidetes' and was isolated from Melosira collected from the Eastern Antarctic coastal zone. The species is of interest because its members produce a wide range of extracellular enzymes capable of degrading proteins and polysaccharides with temperature optima of 20-30°C. This is the first completed genome sequence of a member of the genus Cellulophaga. The 4,888,353 bp long genome with its 4,285 protein-coding and 62 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Riemerella anatipestifer type strain (ATCC 11845 T )

Riemerella anatipestifer (Hendrickson and Hilbert 1932) Segers et al. 1993 is the type species of the genus Riemerella, which belongs to the family Flavobacteriaceae. The species is of interest because of the position of the genus in the phylogenetic tree and because of its role as a pathogen of commercially important avian species worldwide. This is the first completed genome sequence of a member of the genus Riemerella. The 2,155,121 bp long genome with its 2,001 protein-coding and 51 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Weeksella virosa type strain (9751 T )

Weeksella virosa Holmes et al. 1987 is the sole member and type species of the genus Weeksella which belongs to the family Flavobacteriaceae of the phylum Bacteroidetes. Twenty-nine isolates, collected from clinical specimens provided the basis for the taxon description. While the species seems to be a saprophyte of the mucous membranes of healthy man and warm-blooded animals a causal relationship with disease has been reported in a few instances. Except for the ability to produce indole and to hydrolyze Tween and proteins such as casein and gelatin, this aerobic, non-motile, non-pigmented bacterial species is metabolically inert in most traditional biochemical tests. The 2,272,954 bp long genome with its 2,105 protein-coding and 76 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Marivirga tractuosa type strain (H-43 T )

Marivirga tractuosa (Lewin 1969) Nedashkovskaya et al. 2010 is the type species of the genus Marivirga, which belongs to the family Flammeovirgaceae. Members of this genus are of interest because of their gliding motility. The species is of interest because representative strains show resistance to several antibiotics, including gentamicin, kanamycin, neomycin, polymixin and streptomycin. This is the first complete genome sequence of a member of the family Flammeovirgaceae. Here we describe the features of this organism, together with the complete genome sequence and annotation. The 4,511,574 bp long chromosome and the 4,916 bp plasmid with their 3,808 protein-coding and 49 RNA genes are a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Oceanithermus profundus type strain (506 T )

Oceanithermus profundus Miroshnichenko et al. 2003 is the type species of the genus Oceanithermus, which belongs to the family Thermaceae. The genus currently comprises two species whose members are thermophilic and are able to reduce sulfur compounds and nitrite. The organism is adapted to the salinity of sea water, is able to utilize a broad range of carbohydrates, some proteinaceous substrates, organic acids and alcohols. This is the first completed genome sequence of a member of the genus Oceanithermus and the fourth sequence from the family Thermaceae. The 2,439,291 bp long genome with its 2,391 protein-coding and 54 RNA genes consists of one chromosome and a 135,351 bp long plasmid, and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of the thermophilic sulfur-reducer Hippea maritima type strain (MH2 T )

Hippea maritima (Miroshnichenko et al. 1999) is the type species of the genus Hippea, which belongs to the family Desulfurellaceae within the class Deltaproteobacteria. The anaerobic, moderately thermophilic marine sulfur-reducer was first isolated from shallow-water hot vents in Matipur Harbor, Papua New Guinea. H. maritima was of interest for genome sequencing because of its isolated phylogenetic location, as a distant next neighbor of the genus Desulfurella. Strain MH2 T is the first type strain from the order Desulfurellales with a completely sequenced genome. The 1,694,430 bp long linear genome with its 1,723 protein-coding and 57 RNA genes consists of one circular chromosome and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Complete genome sequence of Tolumonas auensis type strain (TA 4T)

Tolumonas auensis (Fischer-Romero et al. 1996) is currently the only validly named species of the genus Tolumonas in the family Aeromonadaceae. The strain is of interest because of its ability to produce toluene from phenylalanine and other phenyl precursors, as well as phenol from tyrosine. This is of interest because toluene is normally considered to be a tracer of anthropogenic pollution in lakes, but T. auensis represents a biogenic source of toluene. Other than Aeromonas hydrophila subsp. hydrophila, T. auensis strain TA 4T is the only other member in the family Aeromonadaceae with a completely sequenced type-strain genome. The 3,471,292-bp chromosome with a total of 3,288 protein-coding and 116 RNA genes was sequenced as part of the DOE Joint Genome Institute Program JBEI 2008.

09 BIOMASS FUELS↗
DOE OSTI2012

Complete genome sequence of the sulfur compounds oxidizing chemolithoautotroph Sulfuricurvum kujiense type strain (YK-1 T )

Sulfuricurvum kujiense Kodama and Watanabe 2004 is the type species of the monotypic genus Sulfuricurvum, which belongs to the family Helicobacteraceae in the class Epsilonproteobacteria. The species is of interest because it is frequently found in crude oil and oil sands where it utilizes various reduced sulfur compounds such as elemental sulfur, sulfide and thiosulfate as electron donors. Members of the species do not utilize sugars, organic acids or hydrocarbons as carbon and energy sources. This genome sequence represents the type strain of the only species in the genus Sulfuricurvum. The genome, which consists of a circular chromosome of 2,574,824 bp length and four plasmids of 118,585 bp, 71,513 bp, 51,014 bp, and 3,421 bp length, respectively, harboring a total of 2,879 protein-coding and 61 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Complete genome sequence of the thermophilic sulfate-reducing ocean bacterium Thermodesulfatator indicus type strain (CIR29812 T )

Thermodesulfatator indicus Moussard et al. 2004 is a member of the Thermodesulfobacteriaceae, a family in the phylum Thermodesulfobacteria that is currently poorly characterized at the genome level. Members of this phylum are of interest because they represent a distinct, deep-branching, Gram-negative lineage. T. indicus is an anaerobic, thermophilic, chemolithoautotrophic sulfate reducer isolated from a deep-sea hydrothermal vent. Here we describe the features of this organism, together with the complete genome sequence, and annotation. The 2,322,224 bp long chromosome with its 2,233 protein-coding and 58 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS2003

Radiation-induced genomic instability: radiation quality and dose response

Genomic instability is a term used to describe a phenomenon that results in the accumulation of multiple changes required to convert a stable genome of a normal cell to an unstable genome characteristic of a tumor. There has been considerable recent debate concerning the importance of genomic instability in human cancer and its temporal occurrence in the carcinogenic process. Radiation is capable of inducing genomic instability in mammalian cells and instability is thought to be the driving force responsible for radiation carcinogenesis. Genomic instability is characterized by a large collection of diverse endpoints that include large-scale chromosomal rearrangements and aberrations, amplification of genetic material, aneuploidy, micronucleus formation, microsatellite instability, and gene mutation. The capacity of radiation to induce genomic instability depends to a large extent on radiation quality or linear energy transfer (LET) and dose. There appears to be a low dose threshold effect with low LET, beyond which no additional genomic instability is induced. Low doses of both high and low LET radiation are capable of inducing this phenomenon. This report reviews data concerning dose rate effects of high and low LET radiation and their capacity to induce genomic instability assayed by chromosomal aberrations, delayed lethal mutations, micronuclei and apoptosis.

Review↗
NASA NTRS2000

Analysis of MIR-18 results for physical and biological dosimetry: radiation shielding effectiveness in LEO

We compare models of radiation transport and biological response to physical and biological dosimetry results from astronauts on the Mir space station. Transport models are shown to be in good agreement with physical measurements and indicate that the ratio of equivalent dose from the Galactic Cosmic Rays (GCR) to protons is about 3/2:1 and that this ratio will increase for exposures to internal organs. Two biological response models are used to compare to the Mir biodosimetry for chromosome aberration in lymphocyte cells; a track-structure model and the linear-quadratic model with linear energy transfer (LET) dependent weighting coefficients. These models are fit to in vitro data for aberration formation in human lymphocytes by photons and charged particles. Both models are found to be in reasonable agreement with data for aberrations in lymphocytes of Mir crew members: however there are differences between the use of LET dependent weighting factors and track structure models for assigning radiation quality factors. The major difference in the models is the increased effectiveness predicted by the track model for low charge and energy ions with LET near 10 keV/micrometers. The results of our calculations indicate that aluminum shielding, although providing important mitigation of the effects of trapped radiation, provides no protective effect from the galactic cosmic rays (GCR) in low-earth orbit (LEO) using either equivalent dose or the number of chromosome aberrations as a measure until about 100 g/cm 2 of material is used.

Flight Experiment↗
NASA NTRS1999

Antigen S1, encoded by the MIC1 gene, is characterized as an epitope of human CD59, enabling measurement of mutagen-induced intragenic deletions in the AL cell system

S1 cell membrane antigen is encoded by the MIC1 gene on human chromosome 11. This antigen has been widely used as a marker for studies in gene mapping or in analysis of mutagen-induced gene deletions/mutations, which utilized the human-hamster hybrid cell-line, AL-J1, carrying human chromosome 11. Evidence is presented here which identifies S1 as an epitope of CD59, a cell membrane complement inhibiting protein. E7.1 monoclonal antibody, specific for the S1 determinant, was found to react strongly with membrane CD59 in Western blotting, and to bind to purified, urinary form of CD59 in ELISAs. Cell membrane expression of S1 on various cell lines always correlated with that of CD59 when examined by immunofluorescent staining. In addition, E7.1 antibody inhibited the complement regulatory function of CD59. Identification of S1 protein as CD59 has increased the scope of the AL cell system by enabling analysis of intragenic mutations, and multiplex PCR analysis of mutated cells is described, showing variable loss of CD59 exons.

Non-NASA Center↗