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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Biochemical and Regulatory Analyses of Xylanolytic Regulons in Caldicellulosiruptor bescii Reveal Genus-Wide Features of Hemicellulose Utilization

Microbial deconstruction of lignocellulose for the production of biofuels and chemicals requires the hydrolysis of heterogeneous hemicelluloses to access the microcrystalline cellulose portion. This work extends previous in vivo and in vitro efforts to characterize hemicellulose utilization by integrating genomic reconstruction, transcriptomic data, operon structures, and biochemical characteristics of key enzymes to understand the deployment and functionality of hemicellulases by the extreme thermophile Caldicellulosiruptor bescii .

Biotechnology & Applied Microbiology↗
DOE OSTI2014

Draft Genome Sequences of 10 Strains of the Genus Exiguobacterium

High-quality draft genome sequences were determined for 10 Exiguobacterium strains in order to provide insight into their evolutionary strategies for speciation and environmental adaptation. The selected genomes include psychrotrophic and thermophilic species from a range of habitats, which will allow for a comparison of metabolic pathways and stress response genes.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

A latitudinal diversity gradient in terrestrial bacteria of the genus Streptomyces

We show that Streptomyces biogeography in soils across North America is influenced by the regional diversification of microorganisms due to dispersal limitation and genetic drift. Streptomyces spp. form desiccation-resistant spores, which can be dispersed on the wind, allowing for a strong test of whether dispersal limitation governs patterns of terrestrial microbial diversity. We employed an approach that has high sensitivity for determining the effects of genetic drift. Specifically, we examined the genetic diversity and phylogeography of physiologically similar Streptomyces strains isolated from geographically distributed yet ecologically similar habitats. We found that Streptomyces beta diversity scales with geographic distance and both beta diversity and phylogenetic diversity manifest in a latitudinal diversity gradient. This pattern of Streptomyces biogeography resembles patterns seen for diverse species of plants and animals, and we therefore evaluated these data in the context of ecological and evolutionary hypotheses proposed to explain latitudinal diversity gradients. The data are consistent with the hypothesis that niche conservatism limits dispersal, and historical patterns of glaciation have limited the time for speciation in higher-latitude sites. Most notably, higher-latitude sites have lower phylogenetic diversity, higher phylogenetic clustering, and evidence of range expansion from lower latitudes. In addition, patterns of beta diversity partition with respect to the glacial history of sites. Furthermore, the data support the hypothesis that extant patterns of Streptomyces biogeography have been driven by historical patterns of glaciation and are the result of demographic range expansion, dispersal limitation, and regional diversification due to drift.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

Clades of Photosynthetic Bacteria Belonging to the Genus Rhodopseudomonas Show Marked Diversity in Light-Harvesting Antenna Complex Gene Composition and Expression

Rhodopseudomonas palustris is a phototrophic purple nonsulfur bacterium that adapts its photosystem to allow growth at a range of light intensities. It does this by adjusting the amount and composition of peripheral light-harvesting (LH) antenna complexes that it synthesizes. Rhodopseudomonas strains are notable for containing numerous sets of light-harvesting genes. We determined the diversity of LH complexes and their transcript levels during growth under high and low light intensities in 20 sequenced genomes of strains related to the species Rhodopseudomonas palustris . The data obtained are a resource for investigators with interests as wide-ranging as the biophysics of photosynthesis, the ecology of phototrophic bacteria, and the use of photosynthetic bacteria for biotechnology applications.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

A new shallow-water mud crab of the genus Hexapanopeus Rathbun, 1898 from Belize (Crustacea: Decapoda: Panopeidae)

A new species of panopeid crab from shallow coastal waters of Belize is formally described and named based upon comparative study of three small specimens obtained in the course of a regional biodiversity survey of decapod crustaceans. The herein designated holotype of Hexapanopeus klausruetzleri n. sp. is a specimen previously included in a comparative molecular phylogenetic analysis that showed it to be closely related to, but genetically distinct from, the western Atlantic species Hexapanopeus angustifrons (Benedict & Rathbun, 1891). Hexapanopeus klausruetzleri n. sp. differs from this widely reported warm-temperate species in both its smoother carapace and pereopod surfaces and its generally more lobiform anterolateral teeth. The unique male first gonopod of the new species also strongly supports its morphological separation from all known congeners and other superficially similar western Atlantic panopeids with which it might be confused. To date, mature females have not been found, and the limited available collections are restricted to the vicinity of Carrie Bow Cay and nearby waters. Fourteen additional species of small panopeid and pseudorhombilid crabs, similar to Hexapanopeus klausruetzleri n. sp. in size and general habitus, were taken in the course of our studies in Belize. Most have not been previously reported from these waters, and several warrant further study to confirm their identifications.

Zoology↗
DOE OSTI2024

New species and records of the symbiotic shrimp genus Leptalpheus Williams, 1965, with notes on Fenneralpheus Felder & Manning, 1986, and preliminary molecular analysis of phylogenetic relationships (Crustacea: Decapoda: Alpheidae)

The shrimp genera Leptalpheus Williams, 1965 and Fenneralpheus Felder & Manning, 1986 are composed entirely of symbiotic species that co-inhabit burrows of infaunal macrocrustaceans. We report extensive collections of these genera from western Atlantic, eastern Pacific and Indo-West Pacific regions. Integrative taxonomy methods, including morphological comparisons and analysis of three mitochondrial genetic markers, are used to test species hypotheses and evolutionary relationships among members of these genera. Our molecular analysis failed to recover Leptalpheus or Fenneralpheus as monophyletic groups. Our results strongly supported the monophyly of three clades composed of species of Leptalpheus, loosely corresponding to previously proposed species groups. Three new species closely related to Leptalpheus forceps Williams, 1965, L. marginalis Anker, 2011, and L. mexicanus Ríos & Carvacho, 1983 are described. Leptalpheus ankeri n. sp., from the Caribbean Sea, Atlantic coast of Florida, and Gulf of Mexico, is a polymorphic species that exhibits two major cheliped morphotypes. Leptalpheus sibo n. sp., from the Pacific coast of Nicaragua, is morphologically very similar to L. ankeri n. sp., likely its transisthmian sister species, and shares its cheliped polymorphism. A reassessment of L. forceps concluded that records of this species from the Caribbean Sea and Brazil are not conspecific with L. forceps sensu stricto from the Atlantic coast of the USA and the Gulf of Mexico, and they are herein described as Leptalpheus degravei n. sp. Based on both molecular and morphological evidence, we found Leptalpheus bicristatus Anker, 2011 to be a junior synonym of L. mexicanus and Leptalpheus canterakintzi Anker & Lazarus, 2015 to be a junior synonym of Leptalpheus azuero Anker, 2011. First reports of Leptalpheus axianassae Dworschak & Coelho, 1999 in Texas and Mexico, Leptalpheus denticulatus Anker & Marin, 2009 in the Mariana Islands, Leptalpheus felderi Anker, Vera Caripe & Lira, 2006 and Leptalpheus lirai Vera Caripe, Pereda & Anker, 2021 in the USA, and Leptalpheus pereirai Anker & Vera Caripe, 2016 in Cuba are included.

Zoology↗
DOE OSTI2021

A robust method of nuclei isolation for single-cell RNA sequencing of solid tissues from the plant genus Populus

Single-cell transcriptome analysis has been extensively applied in humans and animal models to uncover gene expression heterogeneity between the different cell types of a tissue or an organ. It demonstrated its capability to discover key regulatory elements that determine cell fate during developmental programs. Single-cell analysis requires the isolation and labeling of the messenger RNA (mRNA) derived from each cell. These challenges were primarily addressed in mammals by developing microfluidic-based approaches. For plant species whose cells contain cell walls, these approaches have generally required the generation of isolated protoplasts. Many plant tissues’ secondary cell wall hinders enzymatic digestion required for individual protoplast isolation, resulting in an unequal representation of cell types in a protoplast population. This limitation is especially critical for cell types located in the inner layers of a tissue or the inner tissues of an organ. Consequently, single-cell RNA sequencing (scRNA-seq) studies using microfluidic approaches in plants have mainly been restricted to Arabidopsis roots, for which well-established procedures of protoplast isolation are available. Here we present a simple alternative approach to generating high-quality protoplasts from plant tissue by characterizing the mRNA extracted from individual nuclei instead of whole cells. We developed the protocol using two different plant materials with varying cellular complexity levels and cell wall structure, Populus shoot apices, and more lignified stems. Using the 10× Genomics Chromium technology, we show that this procedure results in intact mRNA isolation and limited leakage, with a broad representation of individual cell transcriptomes.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

Two new burrowing mud shrimps of the genus Gilvossius from the Gulf of Mexico (Crustacea: Decapoda: Callianassidae)

Previous reports of Gilvossius setimanus (De Kay, 1844) from the Gulf of Mexico have been based on a population of small specimens from deep offshore continental shelf waters off Texas and larger specimens from shorelines and shallow embayments of western Florida. The offshore population, herein designated Gilvossius fredericqae n. sp., reaches sexual maturity at much smaller size than does Gilvossius setimanuss.s. from the U.S. Atlantic seaboard, a species from which it differs in a number of morphological characters. While maturing at a similar size to G. setimanus s.s., a western Florida population, herein designated Gilvossius howellorum n. sp., differs from it in the 16S mt gene sequence, and from both it and the offshore species in morphology. An updated synonymy and rediagnosis of G. setimanus s.s. herein accompany descriptions of the two new species.

54 ENVIRONMENTAL SCIENCES↗