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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Transcriptome and phenotyping analyses support a role for chloroplast sigma factor 2 in red‐light‐dependent regulation of growth, stress, and photosynthesis

Abstract Sigma factor ( SIG ) proteins contribute to promoter specificity of the plastid‐encoded RNA polymerase during chloroplast genome transcription. All six members of the SIG family, that is, SIG 1– SIG 6, are nuclear‐encoded proteins targeted to chloroplasts. Sigma factor 2 ( SIG 2) is a phytochrome‐regulated protein important for stoichiometric control of the expression of plastid‐ and nuclear‐encoded genes that impact plastid development and plant growth and development. Among SIG factors, SIG 2 is required not only for transcription of chloroplast genes (i.e., anterograde signaling), but also impacts nuclear‐encoded, photosynthesis‐related, and light signaling‐related genes (i.e., retrograde signaling) in response to plastid functional status. Although SIG 2 is involved in photomorphogenesis in Arabidopsis, the molecular bases for its role in light signaling that impacts photomorphogenesis and aspects of photosynthesis have only recently begun to be investigated. Previously, we reported that SIG 2 is necessary for phytochrome‐mediated photomorphogenesis specifically under red (R) and far‐red light, thereby suggesting a link between phytochromes and nuclear‐encoded SIG 2 in light signaling. To explore transcriptional roles of SIG 2 in R‐dependent growth and development, we performed RNA sequencing analysis to compare gene expression in sig2‐2 mutant and Col‐0 wild‐type seedlings at two developmental stages (1‐ and 7‐day). We identified a subset of misregulated genes involved in growth, hormonal cross talk, stress responses, and photosynthesis. To investigate the functional relevance of these gene expression analyses, we performed several comparative phenotyping tests. In these analyses, strong sig2 mutants showed insensitivity to bioactive GA 3 , high intracellular levels of hydrogen peroxide (H 2 O 2 ) indicative of a stress response, and specific defects in photosynthesis, including elevated levels of cyclic electron flow ( CEF ) and nonphotochemical quenching ( NPQ ). We demonstrated that SIG 2 regulates a broader range of physiological responses at the molecular level than previously reported, with specific roles in red‐light‐mediated photomorphogenesis.

Oh, Sookyung↗
DOE OSTI2016

Transcriptome and proteome analysis of nitrogen starvation responses in Synechocystis 6803 ΔglgC , a mutant incapable of glycogen storage

Molecular mechanisms that regulate carbon flux are poorly understood in algae. The ΔglgC mutant of the cyanobacterium Synechocystis sp. PCC 6803 is incapable of glycogen storage and displays an array of physiological responses under nitrogen starvation that are different from wild-type (WT). These include non-bleaching phenotype and the redirection of photosynthetically fixed carbon towards excreted organic acids (overflow metabolism) without biomass growth. To understand the role of gene/protein expression in these responses, we followed the time course of transcripts by genome-scale microarrays and proteins by shotgun proteomics in ΔglgC and WT cells upon nitrogen starvation. Compared to WT, the degradation of phycobilisome rod proteins was delayed and attenuated in the mutant, and the core proteins were less degraded; both contributed to the non-bleaching appearance despite the induction of nblA genes, suggesting the presence of a break in regulation of the phycobilisome degradation pathway downstream of nblA induction. The mutant displayed NtcA-mediated transcriptional response to nitrogen starvation, indicating that it is able to sense nitrogen status. Furthermore, some responses to nitrogen starvation appear to be stronger in the mutant, as shown by the increases in transcripts for the transcriptional regulator, rre37 , which regulates central carbon metabolism. Accordingly, multiple proteins involved in photosynthesis, central carbon metabolism, and carbon storage and utilization showed lower abundance in the mutant. Furthermore, these results indicate that the transition in the central carbon metabolism from growth to overflow metabolism in ΔglgC does not require increases in expression of the overflow pathway enzymes; the transition and non-bleaching phenotype are likely regulated instead at the metabolite level.

09 BIOMASS FUELS↗
DOE OSTI2018

Transcriptome of porcine alveolar macrophages activated by interferon-gamma and lipopolysaccharide

The molecular repertoire of porcine alveolar macrophages (PAMs) is greatly affected by the microenvironment they are exposed to, and specifically by inflammatory cytokines, such as interferon gamma (IFN-γ) released by activated lymphocytes, and microbial products, such as lipopolysaccharide (LPS). In our previous study, we found that IFN-γ- and LPS-activated PAMs (M1) could inhibit porcine reproductive and respiratory syndrome virus (PRRSV) replication. In this study, comprehensive analysis of the expression profiles of the genes associated with the polarization of M0-type PAMs (resting) toward M1 phenotypes (activated by IFN-γ and LPS) led to the following main results: 1) 1551 and 1823 genes were upregulated or downregulated in M1-type PAMs, respectively, compared with M0-type PAMs; 2) Among these, genes encoding ASS1 and CRTAM were the most upregulated and downregulated, respectively; 3) Genes involved in cytokine-cytokine receptor interaction and the JAK/STAT signaling pathway were significantly upregulated, suggesting their critical role in cellular activation; and 4) Genes involved in antigen proteolysis and presentation (immunoproteasome subunits), and inhibition of virus replication (host restriction factors) were significantly upregulated, emphasizing the critical role of these cytokines in immunity. Thus, our results provide important information for future studies on the role of PAM polarization in modulation of infection.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Trichoderma harzianum transcriptome in response to the nematode Pratylenchus brachyurus

The root-lesion nematode Pratylenchus brachyurus causes extensive damage in several crops of economic importance. Fungi of Trichoderma genus have been highlighted as biopesticide agents in the control of several plant diseases. Although it is already widely used in agriculture, there are few studies, especially at the molecular level, that evaluate T. harzianum in the control of P. brachyurus . The aim of the present study was to investigate how interaction with the nematode P. brachyurus influences gene expression of T. harzianum , by using RNA-Seq analysis. Of the 13,932 predicted genes in the T. harzianum genome, 2,922 (21%) were differentially expressed in the presence of P. brachyurus , in relation to the absence of the nematode. Among the differentially expressed genes, we found genes encoding Carbohydrate Active EnZymes (CAZy), MEROPS peptidases, and proteins related to secondary metabolite synthesis. 118 pathways were identified as related to the biosynthesis of secondary metabolites. Additionally, the analysis identified 136 metabolic pathways related to these differentially expressed genes, among which we highlight: aminobenzoate degradation, xenobiotic metabolism by cytochrome P450, and sesquiterpenoid and triterpenoid biosynthesis. Our results contribute to a better understanding of the response of T. harzianum to the nematode P. bracyurus , the potential for biocontrol by this fungus.

59 BASIC BIOLOGICAL SCIENCES↗