United States Department of Energy

About: United States Department of Energy is a government organization based out in Washington D.C., District of Columbia, United States. It is known for research contribution in the topics: Catalysis & Coal. The organization has 13656 authors who have published 14177 publications receiving 556962 citations. The organization is also known as: DOE & Department of Energy.

High intraspecific genome diversity in the model arbuscular mycorrhizal symbiont Rhizophagus irregularis.

Abstract: Arbuscular mycorrhizal fungi (AMF) are known to improve plant fitness through the establishment of mycorrhizal symbioses. Genetic and phenotypic variations among closely related AMF isolates can significantly affect plant growth, but the genomic changes underlying this variability are unclear. To address this issue, we improved the genome assembly and gene annotation of the model strain Rhizophagus irregularis DAOM197198, and compared its gene content with five isolates of R. irregularis sampled in the same field. All isolates harbor striking genome variations, with large numbers of isolate-specific genes, gene family expansions, and evidence of interisolate genetic exchange. The observed variability affects all gene ontology terms and PFAM protein domains, as well as putative mycorrhiza-induced small secreted effector-like proteins and other symbiosis differentially expressed genes. High variability is also found in active transposable elements. Overall, these findings indicate a substantial divergence in the functioning capacity of isolates harvested from the same field, and thus their genetic potential for adaptation to biotic and abiotic changes. Our data also provide a first glimpse into the genome diversity that resides within natural populations of these symbionts, and open avenues for future analyses of plant-AMF interactions that link AMF genome variation with plant phenotype and fitness.

Renewable Electricity Futures for the United States

Abstract: This paper highlights the key results from the Renewable Electricity (RE) Futures Study. It is a detailed consideration of renewable electricity in the United States. The paper focuses on technical issues related to the operability of the U.S. electricity grid and provides initial answers to important questions about the integration of high penetrations of renewable electricity technologies from a national perspective. The results indicate that the future U.S. electricity system that is largely powered by renewable sources is possible and the further work is warranted to investigate this clean generation pathway. The central conclusion of the analysis is that renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of the total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the United States.

Hydrocarbons and their mixtures as alternatives to environmental unfriendly halogenated refrigerants: An updated overview

Abstract: Vapor compression refrigeration systems consume high-grade energy and contribute to global warming and ozone layer depletion due to the environmentally unfriendly refrigerants. The use of hydrocarbons offer good drop-in replacements for the existing halogenated refrigerants in terms of environmental impacts and energy consumption. In this study, a review of the previous studies carried out with hydrocarbons as alternative refrigerants in refrigeration, air conditioning and heat pump, and automobile air conditioning systems is presented. An attempt has been made to cover the current status, possibilities, and problems related to the use of hydrocarbons as alternative refrigerants. Hydrocarbon characteristics, allowable refrigerant charge, flammable properties, and safety considerations are also presented. In addition, the study contains also a useful amount of information about the refrigerant properties, environmental impacts, and replacement strategy of conventional refrigerants. Results showed that in spite of highly flammable characteristics, hydrocarbons can offer proper alternatives to the halogenated refrigerants from the standpoint of environment impact, energy efficiency, COP, refrigerant mass, and compressor discharge temperatures. Roadmap on the future work needs in this field is presented. Finally, a summary of previous studies and strategies on pure HC, HC mixtures, and HC/HFC blends used for different applications has been presented and discussed in detail.

Evolution of an Expanded Sex-Determining Locus in Volvox

Abstract: Although dimorphic sexes have evolved repeatedly in multicellular eukaryotes, their origins are unknown. The mating locus (MT) of the sexually dimorphic multicellular green alga Volvox carteri specifies the production of eggs and sperm and has undergone a remarkable expansion and divergence relative to MT from Chlamydomonas reinhardtii, which is a closely related unicellular species that has equal-sized gametes. Transcriptome analysis revealed a rewired gametic expression program for Volvox MT genes relative to Chlamydomonas and identified multiple gender-specific and sex-regulated transcripts. The retinoblastoma tumor suppressor homolog MAT3 is a Volvox MT gene that displays sexually regulated alternative splicing and evidence of gender-specific selection, both of which are indicative of cooption into the sexual cycle. Thus, sex-determining loci affect the evolution of both sex-related and non-sex-related genes.