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1
Tian, Jing, Yue Pang et Zhong Zhao. « Comparative Transcriptome Analysis of Sophora japonica (L.) Roots Reveals Key Pathways and Genes in Response to PEG-Induced Drought Stress under Different Nitrogen Conditions ». Forests 12, no 5 (20 mai 2021) : 650. http://dx.doi.org/10.3390/f12050650.
Texte intégralRésumé :
Sophora japonica is a native leguminous tree species in China. The high stress tolerance contributes to its long lifespan of thousands of years. The lack of genomic resources greatly limits genetic studies on the stress responses of S. japonica. In this study, RNA-seq was conducted for S. japonica roots grown under short-term 20% polyethylene glycol (PEG) 6000-induced drought stress under normal N and N starvation conditions (1 and 0 mM NH4NO3, respectively). In each of the libraries, we generated more than 25 million clean reads, which were then de novo assembled to 46,852 unigenes with an average length of 1310.49 bp. In the differential expression analyses, more differentially expressed genes (DEGs) were found under drought with N starvation than under single stresses. The number of transcripts identified under N starvation and drought in S. japonica was nearly the same, but more upregulated genes were induced by drought, while more downregulated genes were induced by N starvation. Genes involved in “phenylpropanoid biosynthesis” and “biosynthesis of amino acids” pathways were upregulated according to KEGG enrichment analyses, irrespective of the stress treatments. Additionally, upregulated N metabolism genes were enriched upon drought, and downregulated photosynthesis genes were enriched under N starvation. We found 4,372 and 5,430 drought-responsive DEGs under normal N and N starvation conditions, respectively. N starvation may aggravate drought by downregulating transcripts in the “carbon metabolism”, “ribosome”, “arginine biosynthesis pathway”, “oxidative phosphorylation” and “aminoacyl-tRNA biosynthesis” pathways. We identified 78 genes related to N uptake and assimilation, 38 of which exhibited differential expression under stress. A total of 395 DEGs were categorized as transcription factors, of which AR2/ERF-ERF, WRKY, NAC, MYB, bHLH, C3H and C2C2-Dof families played key roles in drought and N starvation stresses. The transcriptome data obtained, and the genes identified facilitate our understanding of the mechanisms of S. japonica responses to drought and N starvation stresses and provide a molecular foundation for understanding the mechanisms of its long lifespan for breeding resistant varieties for greening.
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Doi, Hideyuki, Fumikazu Akamatsu et Angélica L. González. « Starvation effects on nitrogen and carbon stable isotopes of animals : an insight from meta-analysis of fasting experiments ». Royal Society Open Science 4, no 8 (août 2017) : 170633. http://dx.doi.org/10.1098/rsos.170633.
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Nitrogen and carbon stable isotopic compositions ( δ 15 N and δ 13 C) of consumers have been used for physiological and food web studies. Previous studies have shown δ 15 N and δ 13 C values are affected by several biological and environmental factors during starvation, but the generality of the effect of starvation on δ 15 N and δ 13 C values has not yet been tested. Here, we performed a meta-analysis to evaluate the effects of starvation on δ 15 N and δ 13 C values of consumers, and the underlying factors that may explain the observed variation. The δ 15 N and δ 13 C values were calculated as the differences between the final δ 15 N and δ 13 C values of consumers (post-starvation) and the pre-starvation values on each experiment. Our meta-analysis showed a large variation in the δ 15 N and δ 13 C values of consumers (δ 15 N range: –0.82 to 4.30‰; mean: 0.47‰ and δ 13 C range: –1.92 to 2.62‰; mean: 0.01‰). The δ 15 N values of most consumers increased along the length of the starvation period and were influenced by nitrogen excretion and thermoregulation types, probably because differences in nitrogen metabolism and thermoregulation affect nitrogen processing and excretion rates. None of our predictor variables accounted for the variation in δ 13 C values, which showed both increases and decreases due to fasting. Our findings suggest that starvation results in changes in consumer δ 15 N values which are mainly explained by the length of the fasting period and by nitrogen and energy metabolism, but the underlying mechanisms of the starvation effects on δ 13 C values seem to be more complex than previously thought.
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Richaud, Catherine, Gérald Zabulon, Annette Joder et Jean-Claude Thomas. « Nitrogen or Sulfur Starvation Differentially Affects Phycobilisome Degradation and Expression of the nblA Gene in Synechocystis Strain PCC 6803 ». Journal of Bacteriology 183, no 10 (15 mai 2001) : 2989–94. http://dx.doi.org/10.1128/jb.183.10.2989-2994.2001.
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ABSTRACT Nitrogen (N) limitation in cyanobacteria is well documented: a reduced growth rate is observed, accompanied by a cessation of phycobiliprotein synthesis and an ordered degradation of phycobilisomes (PBS). This leads to a dramatic bleaching phenomenon known as chlorosis. In Synechococcus strain PCC 7942, bleaching due to PBS degradation is also observed under sulfur (S) or phosphorus (P) limitation, and all three are under the control of the nblAgene product, a 59-amino-acid polypeptide which is overexpressed under N, S, and P starvation (J. L. Collier, and A. R. Grossman, EMBO J. 13:1039–1047, 1994). Cyanobase sequence data forSynechocystis strain PCC 6803 indicate the presence of two tandem open reading frames (sll0452 and sll0453) homologous tonblA. We cloned the two genes, identified a unique 5′ mRNA end suggestive of a single transcription start site, and studiednblA expression under conditions of N or S starvation by Northern hybridization: transcripts were detected only under N starvation (no signal is detected in replete medium or with S starvation), whether nblA1 or nblA2 was used as a probe. Mutations in nblA1 and nblA2 were constructed by insertion of a kanamycin cassette; both mutations were nonbleaching under N starvation. Synechocystis strain PCC 6803 does not bleach under S starvation, consistent with the absence ofnblA induction in these conditions. These results were confirmed by analysis of the PBS components: sequential degradation of phycocyanin and associated linkers was observed only under conditions of N starvation. This indicates differences betweenSynechocystis strain PCC 6803 and Synechococcusstrain PCC 7942 in their regulatory and signaling pathways leading to N- and S-starved phenotypes.
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Conesa, Carlos M., Angela Saez, Sara Navarro-Neila, Laura de Lorenzo, Arthur G. Hunt, Edgar B. Sepúlveda, Roberto Baigorri et al. « Alternative Polyadenylation and Salicylic Acid Modulate Root Responses to Low Nitrogen Availability ». Plants 9, no 2 (16 février 2020) : 251. http://dx.doi.org/10.3390/plants9020251.
Texte intégralRésumé :
Nitrogen (N) is probably the most important macronutrient and its scarcity limits plant growth, development and fitness. N starvation response has been largely studied by transcriptomic analyses, but little is known about the role of alternative polyadenylation (APA) in such response. In this work, we show that N starvation modifies poly(A) usage in a large number of transcripts, some of them mediated by FIP1, a component of the polyadenylation machinery. Interestingly, the number of mRNAs isoforms with poly(A) tags located in protein-coding regions or 5′-UTRs significantly increases in response to N starvation. The set of genes affected by APA in response to N deficiency is enriched in N-metabolism, oxidation-reduction processes, response to stresses, and hormone responses, among others. A hormone profile analysis shows that the levels of salicylic acid (SA), a phytohormone that reduces nitrate accumulation and root growth, increase significantly upon N starvation. Meta-analyses of APA-affected and fip1-2-deregulated genes indicate a connection between the nitrogen starvation response and salicylic acid (SA) signaling. Genetic analyses show that SA may be important for preventing the overgrowth of the root system in low N environments. This work provides new insights on how plants interconnect different pathways, such as defense-related hormonal signaling and the regulation of genomic information by APA, to fine-tune the response to low N availability.
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Chardon, Fabien, Gwendal Cueff, Etienne Delannoy, Fabien Aubé, Aurélia Lornac, Magali Bedu, Françoise Gilard et al. « The Consequences of a Disruption in Cyto-Nuclear Coadaptation on the Molecular Response to a Nitrate Starvation in Arabidopsis ». Plants 9, no 5 (1 mai 2020) : 573. http://dx.doi.org/10.3390/plants9050573.
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Mitochondria and chloroplasts are important actors in the plant nutritional efficiency. So, it could be expected that a disruption of the coadaptation between nuclear and organellar genomes impact plant response to nutrient stresses. We addressed this issue using two Arabidopsis accessions, namely Ct-1 and Jea, and their reciprocal cytolines possessing the nuclear genome from one parent and the organellar genomes of the other one. We measured gene expression, and quantified proteins and metabolites under N starvation and non-limiting conditions. We observed a typical response to N starvation at the phenotype and molecular levels. The phenotypical response to N starvation was similar in the cytolines compared to the parents. However, we observed an effect of the disruption of genomic coadaptation at the molecular levels, distinct from the previously described responses to organellar stresses. Strikingly, genes differentially expressed in cytolines compared to parents were mainly repressed in the cytolines. These genes encoded more mitochondrial and nuclear proteins than randomly expected, while N starvation responsive ones were enriched in genes for chloroplast and nuclear proteins. In cytolines, the non-coadapted cytonuclear genomic combination tends to modulate the response to N starvation observed in the parental lines on various biological processes.
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Kumar, Ravinder, Muhammad Arifur Rahman et Taras Y. Nazarko. « Nitrogen Starvation and Stationary Phase Lipophagy Have Distinct Molecular Mechanisms ». International Journal of Molecular Sciences 21, no 23 (29 novembre 2020) : 9094. http://dx.doi.org/10.3390/ijms21239094.
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In yeast, the selective autophagy of intracellular lipid droplets (LDs) or lipophagy can be induced by either nitrogen (N) starvation or carbon limitation (e.g., in the stationary (S) phase). We developed the yeast, Komagataella phaffii (formerly Pichia pastoris), as a new lipophagy model and compared the N-starvation and S-phase lipophagy in over 30 autophagy-related mutants using the Erg6-GFP processing assay. Surprisingly, two lipophagy pathways had hardly overlapping stringent molecular requirements. While the N-starvation lipophagy strictly depended on the core autophagic machinery (Atg1-Atg9, Atg18, and Vps15), vacuole fusion machinery (Vam7 and Ypt7), and vacuolar proteolysis (proteinases A and B), only Atg6 and proteinases A and B were essential for the S-phase lipophagy. The rest of the proteins were only partially required in the S-phase. Moreover, we isolated the prl1 (for the positive regulator of lipophagy 1) mutant affected in the S-phase lipophagy, but not N-starvation lipophagy. The prl1 defect was at a stage of delivery of the LDs from the cytoplasm to the vacuole, further supporting the mechanistically different nature of the two lipophagy pathways. Taken together, our results suggest that N-starvation and S-phase lipophagy have distinct molecular mechanisms.
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McQuail, Josh, Amy Switzer, Lynn Burchell et Sivaramesh Wigneshweraraj. « The RNA-binding protein Hfq assembles into foci-like structures in nitrogen starved Escherichia coli ». Journal of Biological Chemistry 295, no 35 (12 juin 2020) : 12355–67. http://dx.doi.org/10.1074/jbc.ra120.014107.
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The initial adaptive responses to nutrient depletion in bacteria often occur at the level of gene expression. Hfq is an RNA-binding protein present in diverse bacterial lineages that contributes to many different aspects of RNA metabolism during gene expression. Using photoactivated localization microscopy and single-molecule tracking, we demonstrate that Hfq forms a distinct and reversible focus-like structure in Escherichia coli specifically experiencing long-term nitrogen starvation. Using the ability of T7 phage to replicate in nitrogen-starved bacteria as a biological probe of E. coli cell function during nitrogen starvation, we demonstrate that Hfq foci have a role in the adaptive response of E. coli to long-term nitrogen starvation. We further show that Hfq foci formation does not depend on gene expression once nitrogen starvation has set in and occurs indepen-dently of the transcription factor N-regulatory protein C, which activates the initial adaptive response to N starvation in E. coli. These results serve as a paradigm to demonstrate that bacterial adaptation to long-term nutrient starvation can be spatiotemporally coordinated and can occur independently of de novo gene expression during starvation.
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Ahmed,, A., E. Sayed-Ahmed, A. Bayomey et F. El-Deeb. « SOME BIOLOGICAL ASPECTS ¡N CONSEQUENCE OF STARVATION IN RATS ». Journal of Food and Dairy Sciences 31, no 12 (1 décembre 2006) : 7765–74. http://dx.doi.org/10.21608/jfds.2006.236901.
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Bedu, Magali, Anne Marmagne, Céline Masclaux-Daubresse et Fabien Chardon. « Transcriptional Plasticity of Autophagy-Related Genes Correlates with the Genetic Response to Nitrate Starvation in Arabidopsis Thaliana ». Cells 9, no 4 (20 avril 2020) : 1021. http://dx.doi.org/10.3390/cells9041021.
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In eukaryotes, autophagy, a catabolic mechanism for macromolecule and protein recycling, allows the maintenance of amino acid pools and nutrient remobilization. For a better understanding of the relationship between autophagy and nitrogen metabolism, we studied the transcriptional plasticity of autophagy genes (ATG) in nine Arabidopsis accessions grown under normal and nitrate starvation conditions. The status of the N metabolism in accessions was monitored by measuring the relative expression of 11 genes related to N metabolism in rosette leaves. The transcriptional variation of the genes coding for enzymes involved in ammonium assimilation characterize the genetic diversity of the response to nitrate starvation. Starvation enhanced the expression of most of the autophagy genes tested, suggesting a control of autophagy at transcriptomic level by nitrogen. The diversity of the gene responses among natural accessions revealed the genetic variation existing for autophagy independently of the nutritive condition, and the degree of response to nitrate starvation. We showed here that the genetic diversity of the expression of N metabolism genes correlates with that of the ATG genes in the two nutritive conditions, suggesting that the basal autophagy activity is part of the integral response of the N metabolism to nitrate availability.
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Beleggia, Romina, Nooshin Omranian, Yan Holtz, Tania Gioia, Fabio Fiorani, Franca M. Nigro, Nicola Pecchioni et al. « Comparative Analysis Based on Transcriptomics and Metabolomics Data Reveal Differences between Emmer and Durum Wheat in Response to Nitrogen Starvation ». International Journal of Molecular Sciences 22, no 9 (30 avril 2021) : 4790. http://dx.doi.org/10.3390/ijms22094790.
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Mounting evidence indicates the key role of nitrogen (N) on diverse processes in plant, including development and defense. Using a combined transcriptomics and metabolomics approach, we studied the response of seedlings to N starvation of two different tetraploid wheat genotypes from the two main domesticated subspecies: emmer and durum wheat. We found that durum wheat exhibits broader and stronger response in comparison to emmer as seen from the expression pattern of both genes and metabolites and gene enrichment analysis. They showed major differences in the responses to N starvation for transcription factor families, emmer showed differential reduction in the levels of primary metabolites while durum wheat exhibited increased levels of most of them to N starvation. The correlation-based networks, including the differentially expressed genes and metabolites, revealed tighter regulation of metabolism in durum wheat in comparison to emmer. We also found that glutamate and γ-aminobutyric acid (GABA) had highest values of centrality in the metabolic correlation network, suggesting their critical role in the genotype-specific response to N starvation of emmer and durum wheat, respectively. Moreover, this finding indicates that there might be contrasting strategies associated to GABA and glutamate signaling modulating shoot vs. root growth in the two different wheat subspecies.
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Liu, Haipei, Amanda J. Able et Jason A. Able. « Nitrogen Starvation-Responsive MicroRNAs Are Affected by Transgenerational Stress in Durum Wheat Seedlings ». Plants 10, no 5 (21 avril 2021) : 826. http://dx.doi.org/10.3390/plants10050826.
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Stress events have transgenerational effects on plant growth and development. In Mediterranean regions, water-deficit and heat (WH) stress is a frequent issue that negatively affects crop yield and quality. Nitrogen (N) is an essential plant macronutrient and often a yield-limiting factor for crops. Here, the response of durum wheat seedlings to N starvation under the transgenerational effects of WH stress was investigated in two genotypes. Both genotypes showed a significant reduction in seedling height, leaf number, shoot and root weight (fresh and dry), primary root length, and chlorophyll content under N starvation stress. However, in the WH stress-tolerant genotype, the percentage reduction of most traits was lower in progeny from the stressed parents than progeny from the control parents. Small RNA sequencing identified 1534 microRNAs in different treatment groups. Differentially expressed microRNAs (DEMs) were characterized subject to N starvation, parental stress and genotype factors, with their target genes identified in silico. GO and KEGG enrichment analyses revealed the biological functions, associated with DEM-target modules in stress adaptation processes, that could contribute to the phenotypic differences observed between the two genotypes. The study provides the first evidence of the transgenerational effects of WH stress on the N starvation response in durum wheat.
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Elia, M., S. Wood, K. Khan et E. Pullicino. « Ketone body metabolism in lean male adults during short-term starvation, with particular reference to forearm muscle metabolism ». Clinical Science 78, no 6 (1 juin 1990) : 579–84. http://dx.doi.org/10.1042/cs0780579.
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1. Thirty-three arteriovenous forearm catheterization studies were carried out in 19 lean subjects starving for 12–14 h(n = 13), 30–36 h (n = 7) and 60–66 h (n = 13). Forearm blood flow was measured in order to calculate the flux of various substrates. At the same time, whole-body oxidation of fat, carbohydrate and protein was calculated using indirect calorimetry and urinary nitrogen excretion. 2. After an overnight fast (12–14 h), whole-body resting energy expenditure was accounted for by the oxidation of protein (15%), carbohydrate (17%) and fat (68%). At 30–36 h and 60–66 h of starvation, essentially all the non-protein energy was derived from the oxidation of fat (directly plus indirectly via ketone bodies). 3. After an overnight fast, acetoacetate and 3-hydroxybutyrate were taken up by forearm muscle at a rate which could account for 5% of the resting O2 consumption of this tissue. As starvation progressed, forearm muscle took up more acetoacetate and released 3-hydroxybutyrate so that the net uptake of ketone bodies was sufficient to account for about 10% of the resting O2 consumption at 30–36 h of starvation and about 20% at 60–66 h of starvation. 4. The uptake of circulating non-esterified fatty acids by forearm muscle accounted for a greater proportion of the forearm O2 consumption than the uptake of ketone bodies at all times studied. The release of lactate and alanine was significantly greater at 36–40 h and 60–66 h of starvation compared with 12–14 h of starvation, but that of glucose did not change significantly. 5. The results suggest that during early starvation: (a) the release of 3-hydroxybutyrate by muscle (36–66 h starvation) contributes to the circulating 3-hydroxybutyrate concentration, (b) the contribution of ketone bodies to oxidative metabolism in lean subjects is variable but considerably lower than the generally accepted values in obese individuals, and (c) the dominant energy source for the resting muscle of lean individuals between 12 and 66 h of starvation is non-esterified fatty acids.
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Kohno, Shohei, Yuji Shiozaki, Audrey L. Keenan, Shinobu Miyazaki-Anzai et Makoto Miyazaki. « An N-terminal–truncated isoform of FAM134B (FAM134B-2) regulates starvation-induced hepatic selective ER-phagy ». Life Science Alliance 2, no 3 (17 mai 2019) : e201900340. http://dx.doi.org/10.26508/lsa.201900340.
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Autophagy is a conserved system that adapts to nutrient starvation, after which proteins and organelles are degraded to recycle amino acids in response to starvation. Recently, the ER was added to the list of targets of autophagic degradation. Autophagic degradation pathways of bulk ER and the specific proteins sorted through the ER are considered key mechanisms in maintaining ER homeostasis. Four ER-resident proteins (FAM134B, CCPG1, SEC62, and RTN3) have been identified as ER-resident cargo receptors, which contain LC3-interacting regions. In this study, we identified an N-terminal–truncated isoform of FAM134B (FAM134B-2) that contributes to starvation-induced ER-related autophagy. Hepatic FAM134B-2 but not full-length FAM134B (FAM134B-1) is expressed in a fed state. Starvation drastically induces FAM134B-2 but no other ER-resident cargo receptors through transcriptional activation by C/EBPβ. C/EBPβ overexpression increases FAM134B-2 recruitment into autophagosomes and lysosomal degradation. FAM134B-2 regulates lysosomal degradation of ER-retained secretory proteins such as ApoCIII. This study demonstrates that the C/EBPβ-FAM134B-2 axis regulates starvation-induced selective ER-phagy.
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Lemma, Annabel S., Nashaly Soto-Echevarria et Mark P. Brynildsen. « Fluoroquinolone Persistence in Escherichia coli Requires DNA Repair despite Differing between Starving Populations ». Microorganisms 10, no 2 (26 janvier 2022) : 286. http://dx.doi.org/10.3390/microorganisms10020286.
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When faced with nutritional deprivation, bacteria undergo a range of metabolic, regulatory, and biosynthetic changes. Those adjustments, which can be specific or independent of the missing nutrient, often alter bacterial tolerance to antibiotics. Here, using fluoroquinolones, we quantified Escherichia coli persister levels in cultures experiencing starvation from a lack of carbon (C), nitrogen (N), phosphorous (P), or magnesium (Mg2+). Interestingly, persister levels varied significantly based on the type of starvation as well as fluoroquinolone used with N-starved populations exhibiting the highest persistence to levofloxacin, and P-starved populations exhibiting the highest persistence to moxifloxacin. However, regardless of the type of starvation or fluoroquinolone used, DNA repair was required by persisters, with ∆recA and ∆recB uniformly exhibiting the lowest persistence of the mutants assayed. These results suggest that while the type of starvation and fluoroquinolone will modulate the level of persistence, the importance of homologous recombination is consistently observed, which provides further support for efforts to target homologous recombination for anti-persister purposes.
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Leganés, Francisco, Karl Forchhammer et Francisca Fernández-Piñas. « Role of calcium in acclimation of the cyanobacterium Synechococcus elongatus PCC 7942 to nitrogen starvation ». Microbiology 155, no 1 (1 janvier 2009) : 25–34. http://dx.doi.org/10.1099/mic.0.022251-0.
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A Ca2+ signal is required for the process of heterocyst differentiation in the filamentous diazotrophic cyanobacterium Anabaena sp. PCC 7120. This paper presents evidence that a transient increase in intracellular free Ca2+ is also involved in acclimation to nitrogen starvation in the unicellular non-diazotrophic cyanobacterium Synechococcus elongatus PCC 7942. The Ca2+ transient was triggered in response to nitrogen step-down or the addition of 2-oxoglutarate (2-OG), or its analogues 2,2-difluoropentanedioic acid (DFPA) and 2-methylenepentanedioic acid (2-MPA), to cells growing with combined nitrogen, suggesting that an increase in intracellular 2-OG levels precedes the Ca2+ transient. The signalling protein PII and the transcriptional regulator NtcA appear to be needed to trigger the signal. Suppression of the Ca2+ transient by the intracellular Ca2+ chelator N,N′-[1,2-ethanediylbis(oxy-2,1-phenylene)]bis[N-[2-[(acetyloxy)methoxy]-2-oxoethyl]]-,bis[(acetyloxy)methyl] ester (BAPTA-AM) inhibited expression of the glnB and glnN genes, which are involved in acclimation to nitrogen starvation and transcriptionally activated by NtcA. BAPTA-AM treatment partially inhibited expression of the nblA gene, which is involved in phycobiliprotein degradation following nutrient starvation and is regulated by NtcA and NblR; in close agreement, BAPTA-AM treatment partially inhibited bleaching following nitrogen starvation. Taken together, the results presented here strongly suggest an involvement of a defined Ca2+ transient in acclimation of S. elongatus to nitrogen starvation through NtcA-dependent regulation.
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Smith, D. M., et P. H. Sugden. « Contrasting response of protein degradation to starvation and insulin as measured by release of Nτ-methylhistidine or phenylalanine from the perfused rat heart ». Biochemical Journal 237, no 2 (15 juillet 1986) : 391–95. http://dx.doi.org/10.1042/bj2370391.
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An isotope-dilution method is described for the measurement of N tau-methylhistidine release from the perfused rat heart. We argue that release of N tau-methylhistidine is indicative of cardiac actin degradation. N tau-Methylhistidine release is compared with phenylalanine release in the presence of cycloheximide (phenylalanine release being a measure of degradation of mixed proteins). In hearts perfused with glucose plus acetate, the rate of actin degradation was increased by starvation and was not inhibited by insulin. In contrast, the rate of mixed-protein degradation was decreased by starvation and was inhibited by insulin. The fractional rate of degradation of mixed proteins in hearts from fed or starved rats was greater than that for actin. It is suggested that there are at least two pools of intracellular protein, the degradation rates of which differ in terms of their response to insulin and starvation.
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Kim, Sang-Soo, Byung-Hyun Moon, Gyu-Tae Seo et Cho-Hee Yoon. « The effects of starvation on physical characteristics of flocs in SBR for treating saline wastewater ». Water Science and Technology 56, no 7 (1 octobre 2007) : 41–46. http://dx.doi.org/10.2166/wst.2007.691.
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This study focused on the effects of starvation on physical characteristics of flocs in SBR for treating saline wastewater. Feeding was stopped for 5 and 15 days. A time response of the floc to these starvation periods was monitored as well as the removal efficiencies of pollutants. Correlation between the physical characteristics of flocs and settling of sludge was conducted. As the starvation periods were increased, there was a shift in the floc size distribution from a high proportion of large flocs to the development of small size flocs. The fractal dimension of flocs also decreased, as starvation periods were increased. From the results, the effect of starvation on SBR treating saline wastewater can be ordered as follows: CODMn removal < floc size and fractal dimension < T-N removal < T-P removal.
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Sims, G. K. « Nitrogen starvation promotes biodegradation of N-heterocyclic compounds in soil ». Soil Biology and Biochemistry 38, no 8 (août 2006) : 2478–80. http://dx.doi.org/10.1016/j.soilbio.2006.01.006.
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GIRARDIN, P., A. DELTOUR et M. TOLLENAAR. « EFFECT OF TEMPORARY N STARVATION IN MAIZE ON LEAF SENESCENCE ». Canadian Journal of Plant Science 65, no 4 (1 octobre 1985) : 819–29. http://dx.doi.org/10.4141/cjps85-108.
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A prerequisite for an informed strategy regarding nitrogen application in maize (Zea mays L.) is a knowledge of the physiology of plant responses to nitrogen. This study consisted of two experiments on maize plants grown in pails. One experiment was conducted in controlled-environment growth rooms, the other was conducted in the field. N-deficient and control maize plants were evaluated for photosynthetic rate (P), chlorophyll content (CC), nitrogen content, and green leaf area; comparisons between these four parameters were made. During N starvation, rate of senescence (i.e. decrease in green leaf area) of the old leaves was higher in N-deprived plants than in control plants. P and CC of all leaves in the N-deficient treatment decreased during nitrogen withdrawal. After the deprivation period, when the plants were resupplied with N, senescence was delayed relative to control plants. The increase of CC in treatment plants was slower than the recovery of photosynthetic rate; in fact, CC was a poor indicator of photosynthetic activity. The delay in leaf senescence corresponded with regreening in leaves of N-deprived plants following N addition. This delay could be partly explained by an overcompensation in plant N requirement involving both a rapid increase in P, and a slower increase in CC. The effects of resupplying plants with nitrogen following a N-deprivation period lead us to believe that the observed leaf yellowing is actually a premature senescence which is reversible, and that a low N content is not the single causal factor of senescence.Key words: Chlorophyll content, leaf area, photosynthetic rate, Zea mays L.
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Su, Hui, Xueying Zhang, Yuqing He, Linying Li, Yuefei Wang, Gaojie Hong et Ping Xu. « Transcriptomic Analysis Reveals the Molecular Adaptation of Three Major Secondary Metabolic Pathways to Multiple Macronutrient Starvation in Tea (Camellia sinensis) ». Genes 11, no 3 (25 février 2020) : 241. http://dx.doi.org/10.3390/genes11030241.
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Tea (Camellia sinensis (L.) O. Kuntze) is a widely consumed beverage. Lack of macronutrients is a major cause of tea yield and quality losses. Though the effects of macronutrient starvation on tea metabolism have been studied, little is known about their molecular mechanisms. Hence, we investigated changes in the gene expression of tea plants under nitrogen (N), phosphate (P), and potassium (K) deficient conditions by RNA-sequencing. A total of 9103 differentially expressed genes (DEG) were identified. Function enrichment analysis showed that many biological processes and pathways were common to N, P, and K starvation. In particular, cis-element analysis of promoter of genes uncovered that members of the WRKY, MYB, bHLH, NF-Y, NAC, Trihelix, and GATA families were more likely to regulate genes involved in catechins, l-theanine, and caffeine biosynthetic pathways. Our results provide a comprehensive insight into the mechanisms of responses to N, P, and K starvation, and a global basis for the improvement of tea quality and molecular breeding.
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Chen, Ranhong, Wanting Chen, Mulualem Tigabu, Weimin Zhong, Yushan Li, Xiangqing Ma et Ming Li. « Screening and Evaluation of Stable Reference Genes for Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) Analysis in Chinese Fir Roots under Water, Phosphorus, and Nitrogen Stresses ». Forests 10, no 12 (1 décembre 2019) : 1087. http://dx.doi.org/10.3390/f10121087.
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Chinese fir (Cunninghamia lanceolata) is an economical important timber species widely planted in southeastern Asia. Decline in yield and productivity during successive rotation is believed to be linked with abiotic stress, such as drought stress and nitrogen (N) and phosphorus (P) starvation. Molecular breeding could be an option to develop tolerant genotypes. For gene expression studies using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR), stable reference genes are needed for normalization of gene expression under different experimental conditions. However, there is no internal reference genes identified for Chinese fir under abiotic stresses. Thus, nine internal reference genes based on transcriptome data were selected and analyzed in the root of Chinese fir under drought stress and N and P starvation. Data were analyzed using geNorm, NormFinder, and BestKeeper, to screen and identify the best reference genes. The results showed that the UBQ and GAPDH genes were the two most stable genes under drought stress and the Actin1 and GAPDH were the two most stable genes under P starvation. Further, it was discovered that the Actin1 and UBC were the two most stable genes under N starvation among nine candidate reference genes. The gene expression of drought stress induced expression protein 14-3-3-4, the P transporter gene ClPht1;3, and the nitrate transporter gene NRT1.1 were used to verify the stability of the selected reference genes under drought stress and P and N starvation, respectively, and the results revealed that the screened reference genes were sufficient to normalize expression of the target genes. In conclusion, the results demonstrate that the stability of reference genes was closely related to the external conditions and reference genes applied to the roots of Chinese fir under different abiotic stress treatments were different. Our data will facilitate further studies on stress ecology and gene function analysis in Chinese fir.
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Wu, Zhihua, Hong Liu, Wen Huang, Lisha Yi, Erdai Qin, Tiange Yang, Jing Wang et Rui Qin. « Genome-Wide Identification, Characterization, and Regulation of RWP-RK Gene Family in the Nitrogen-Fixing Clade ». Plants 9, no 9 (11 septembre 2020) : 1178. http://dx.doi.org/10.3390/plants9091178.
Texte intégralRésumé :
RWP-RK is a plant-specific family of transcription factors, involved in nitrate response, gametogenesis, and nodulation. However, genome-wide characterization, phylogeny, and the regulation of RWP-RK genes in the nodulating and non-nodulating plant species of nitrogen-fixing clade (NFC) are widely unknown. Therefore, we identified a total of 292 RWP-RKs, including 278 RWP-RKs from 25 NFC species and 14 RWP-RKs from the outgroup, Arabidopsis thaliana. We classified the 292 RWP-RKs in two subfamilies: the NIN-like proteins (NLPs) and the RWP-RK domain proteins (RKDs). The transcriptome and phylogenetic analysis of RWP-RKs suggested that, compared to RKD genes, the NLP genes were just upregulated in nitrate response and nodulation. Moreover, nodule-specific NLP genes of some nodulating NFC species may have a common ancestor (OG0002084) with AtNLP genes in A. thaliana. Further, co-expression networks of A.thaliana under N-starvation and N-supplementation conditions revealed that there is a higher correlation between expression of AtNLP genes and symbiotic genes during N-starvation. In P. vulgaris, we confirmed that N-starvation stimulated nodulation by regulating expression of PvNLP2, closely related to AtNLP6 and AtNLP7 with another common origin (OG0004041). Taken together, we concluded that different origins of the NLP genes involved in both N-starvation response and specific expression of nodulation would contribute to the evolution of nodulation in NFC plant species. Our results shed light on the phylogenetic relationships of NLP genes and their differential regulation in nitrate response of A. thaliana and nodulation of NFC.
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Lu, Li-Lan, Yu-Xiu Zhang et Yan-Fang Yang. « Integrative transcriptomic and metabolomic analyses unveil tanshinone biosynthesis in Salvia miltiorrhiza root under N starvation stress ». PLOS ONE 17, no 8 (25 août 2022) : e0273495. http://dx.doi.org/10.1371/journal.pone.0273495.
Texte intégralRésumé :
Salvia miltiorrhiza is a model plant for Chinese herbal medicine with significant pharmacologic effects due to its tanshinone components. Our previous study indicated that nitrogen starvation stress increased its tanshinone content. However, the molecular mechanism of this low nitrogen-induced tanshinone biosynthesis is still unclear. Thus, this study aimed to elucidate the molecular mechanism of tanshinone biosynthesis in S. miltiorrhiza under different N conditions [N-free (N0), low-N (Nl), and full-N (Nf, as control) conditions] by using transcriptome and metabolome analyses. Our results showed 3,437 and 2,274 differentially expressed unigenes between N0 and Nf as well as Nl and Nf root samples, respectively. N starvation (N0 and Nl) promoted the expression of the genes involved in the MVA and MEP pathway of tanshinone and terpenoid backbone biosynthesis. Gene ontology and KEGG analyses revealed that terpenoid backbone biosynthesis, hormone signal transduction, and phenylpropanoid biosynthesis were promoted under N starvation conditions, whereas starch and sucrose metabolisms, nitrogen and phosphorus metabolisms, as well as membrane development were inhibited. Furthermore, metabolome analysis showed that metabolite compounds and biosynthesis of secondary metabolites were upregulated. This study provided a novel insight into the molecular mechanisms of tanshinone production in S. miltiorrhiza in response to nitrogen stress.
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Bollmann, Annette, Marie-José Bär-Gilissen et Hendrikus J. Laanbroek. « Growth at Low Ammonium Concentrations and Starvation Response as Potential Factors Involved in Niche Differentiation among Ammonia-Oxidizing Bacteria ». Applied and Environmental Microbiology 68, no 10 (octobre 2002) : 4751–57. http://dx.doi.org/10.1128/aem.68.10.4751-4757.2002.
Texte intégralRésumé :
ABSTRACT In nature, ammonia-oxidizing bacteria have to compete with heterotrophic bacteria and plants for limiting amounts of ammonium. Previous laboratory experiments conducted with Nitrosomonas europaea suggested that ammonia-oxidizing bacteria are weak competitors for ammonium. To obtain a better insight into possible methods of niche differentiation among ammonia-oxidizing bacteria, we carried out a growth experiment at low ammonium concentrations with N. europaea and the ammonia oxidizer G5-7, a close relative of Nitrosomonas oligotropha belonging to Nitrosomonas cluster 6a, enriched from a freshwater sediment. Additionally, we compared the starvation behavior of the newly enriched ammonia oxidizer G5-7 to that of N. europaea. The growth experiment at low ammonium concentrations showed that strain G5-7 was able to outcompete N. europaea at growth-limiting substrate concentrations of about 10 μM ammonium, suggesting better growth abilities of the ammonia oxidizer G5-7 at low ammonium concentrations. However, N. europaea displayed a more favorable starvation response. After 1 to 10 weeks of ammonium deprivation, N. europaea became almost immediately active after the addition of fresh ammonium and converted the added ammonium within 48 to 96 h. In contrast, the regeneration time of the ammonia oxidizer G5-7 increased with increasing starvation time. Taken together, these results provide insight into possible mechanisms of niche differentiation for the ammonia-oxidizing bacteria studied. The Nitrosomonas cluster 6a member, G5-7, is able to grow at ammonium concentrations at which the growth of N. europaea, belonging to Nitrosomonas cluster 7, has already ceased, providing an advantage in habitats with continuously low ammonium concentrations. On the other hand, the ability of N. europaea to become active again after longer periods of starvation for ammonium may allow better exploitation of irregular pulses of ammonium in the environment.
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Lavrinovičs, Aigars, Fredrika Murby, Elīna Zīverte, Linda Mežule et Tālis Juhna. « Increasing Phosphorus Uptake Efficiency by Phosphorus-Starved Microalgae for Municipal Wastewater Post-Treatment ». Microorganisms 9, no 8 (27 juillet 2021) : 1598. http://dx.doi.org/10.3390/microorganisms9081598.
Texte intégralRésumé :
Four microalgal species, Chlorella vulgaris, Botryococcus braunii, Ankistrodesmus falcatus, and Tetradesmus obliquus were studied for enhanced phosphorus removal from municipal wastewater after their exposure to phosphorus starvation. Microalgae were exposed to phosphorus starvation conditions for three and five days and then used in a batch experiment to purify an effluent from a small WWTP. After 3-day P-starvation, C. vulgaris biomass growth rate increased by 50% and its PO4 removal rate reached > 99% within 7 days. B. braunii maintained good biomass growth rate and nutrient removal regardless of the P-starvation. All species showed 2–5 times higher alkaline phosphatase activity increase for P-starved biomass than at the reference conditions, responding to the decline of PO4 concentration in wastewater and biomass poly-P content. The overall efficiency of biomass P-starvation on enhanced phosphorus uptake was found to be dependent on the species, N/P molar ratio in the wastewater, as well as the biomass P content.
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Dias, F. C. F., D. Dadarwal, M. Honparkhe, G. P. Adams, R. J. Mapletoft et J. Singh. « 313 EFFECT OF DURATION OF THE GROWING PHASE OF OVULATORY FOLLICLES IN SUPERSTIMULATED HEIFERS ON OOCYTE COMPETENCE AFTER IN VITRO FERTILIZATION ». Reproduction, Fertility and Development 25, no 1 (2013) : 303. http://dx.doi.org/10.1071/rdv25n1ab313.
Texte intégralRésumé :
We tested the hypotheses that extending the duration of follicular growth by superstimulation increases oocyte competence, and that FSH starvation at the end of superstimulatory treatment decreases oocyte competence. Heifers were allocated randomly to short FSH duration (n = 8), FSH starvation (n = 8), or long FSH duration (n = 8) groups. Five to 8 days after ovulation, transvaginal ultrasound-guided follicle ablation was done to synchronize follicle wave emergence, and a progesterone-releasing device (CIDR; Pfizer Animal Health, New York, NY, USA) was placed intravaginally. Short FSH and FSH starvation groups were given 8 doses of FSH (Folltropin-V; Bioniche Animal Health Inc., Belleville, ON, Canada) IM, whereas the long FSH group was given 14 doses of FSH at 12-h intervals, starting from the day of wave emergence (Day 0). Prostaglandin F2α (PGF) was administered twice, 12 h apart, on Day 3 in the short FSH group and on Day 6 in the other 2 groups. In all heifers, the CIDR was removed at the time of the second PGF treatment; pLH (Lutropin-V; Bioniche Animal Health Inc.) was given IM 24 h after CIDR removal, and cumulus–oocyte complexes (COC) were collected 24 h after pLH treatment. The COC were matured in vitro (6 h) and fertilized (IVF), and the embryos were cultured for 10 days. At 12 h after pLH, the long FSH group had a greater number of ≥9 mm follicles than the FSH starvation and short FSH groups (25.4 ± 5.3 v. 11.0 ± 2.1 and 10.6 ± 2.3, respectively; P < 0.03). The long FSH group also had more expanded COC than the FSH starvation group (P < 0.001), but did not differ from the short FSH group (93, 54, and 74%, respectively). The FSH starvation group had a greater proportion (P < 0.0001) of partially expanded COC (32%) and poor quality oocytes (70%) than did the long (1 and 33%) and short (4 and 45%) FSH groups; oocyte quality did not differ between long and short FSH groups. At 48 h after IVF, the cleavage rate was lower in the FSH starvation group compared with the short and long FSH groups (35, 54, and 56%, respectively; P = 0.003). After 9 days in culture, embryo development (morula + blastocyst) in the FSH starvation group was lower than that in the long FSH group, (18 v. 37%; P = 0.04), but did not differ from that in the short FSH group (25%). After removal of the data of one heifer in the FSH starvation group that produced 52% of total embryos in that group (outlier), the Day 9 blastocyst rate was lower in the FSH starvation group than in the short and long FSH groups (2% v. 14 and 21%, respectively; P = 0.02). In conclusion, extending the standard superstimulation protocol by 3 days enhanced ovarian response to FSH treatment, but did not improve oocyte competence, whereas a period of FSH starvation after FSH treatment compromised oocyte quality and embryo development.
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Biddinger, Eric J., Chunming Liu, Robert J. Joly et K. G. Raghothama. « Physiological and Molecular Responses of Aeroponically Grown Tomato Plants to Phosphorus Deficiency ». Journal of the American Society for Horticultural Science 123, no 2 (mars 1998) : 330–33. http://dx.doi.org/10.21273/jashs.123.2.330.
Texte intégralRésumé :
Phosphorus is one of the essential but limiting nutrients in nature. In this study, we link the physiological changes occurring under phosphate (Pi) starvation to gene expression. Roots of aeroponically grown tomato (Lycopersicon esculentum L.) plants were sprayed intermittently with nutrient solutions containing varying concentrations of P. Decreasing the concentration of Pi in the nutrient solution resulted in reduced biomass production and altered the tissue concentration of nutrients in roots and shoots. Phosphorus starvation increased the root:shoot biomass ratio and decreased net CO2 assimilation and stomatal conductance. Phosphorus concentrations in roots and shoots decreased with decreasing concentration of Pi in the nutrient solution. Pi-deficient plants had a higher concentration of Ca in roots and Mg in shoots. Expression of the Pi starvation-induced gene, TPSI1, persisted even after 3 weeks of Pi starvation. The transcript accumulation in leaves was found to be a specific response to Pi starvation and not to the indirect effects of altered N, K, Fe, Mg, or Ca status. Accumulation of transcripts was also observed in stem and petioles, suggesting a global role for TPSI1 during Pi starvation response of tomatoes.
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Marciano, David, Akabayov et Rotblat. « The Amuvatinib Derivative, N-(2H-1,3-Benzodioxol-5-yl)-4-{thieno[3,2-d]pyrimidin-4-yl}piperazine-1-carboxamide, Inhibits Mitochondria and Kills Tumor Cells under Glucose Starvation ». International Journal of Molecular Sciences 21, no 3 (4 février 2020) : 1041. http://dx.doi.org/10.3390/ijms21031041.
Texte intégralRésumé :
Glucose levels inside solid tumors are low as compared with normal surrounding tissue, forcing tumor cells to reprogram their metabolism to adapt to such low glucose conditions. Unlike normal tissue, tumor cells experience glucose starvation, making the targeting of pathways supporting survival during glucose starvation an interesting therapeutic strategy in oncology. Using high-throughput screening, we previously identified small molecules that selectively kill cells exposed to glucose starvation. One of the identified compounds was the kinase inhibitor amuvatinib. To identify new molecules with potential antineoplastic activity, we procured 12 amuvatinib derivatives and tested their selective toxicity towards glucose-starved tumor cells. One of the amuvatinib derivatives, N-(2H-1,3-benzodioxol-5-yl)-4-{thieno[3,2-d]pyrimidin-4-yl}piperazine-1-carboxamide, termed compound 6, was found to be efficacious in tumor cells experiencing glucose starvation. In line with the known dependence of glucose-starved cells on the mitochondria, compound 6 inhibits mitochondrial membrane potential. These findings support the concept that tumor cells are dependent on mitochondria under glucose starvation, and bring forth compound 6 as a new molecule with potential antitumor activity for the treatment of glucose-starved tumors.
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Dias, F. C. F., E. Costa, G. P. Adams, R. J. Mapletoft, J. Kastelic, O. Dochi et J. Singh. « Effect of duration of the growing phase of ovulatory follicles on oocyte competence in superstimulated cattle ». Reproduction, Fertility and Development 25, no 3 (2013) : 523. http://dx.doi.org/10.1071/rd11284.
Texte intégralRésumé :
In the present study, we tested the hypotheses that oocyte competence is compromised by a longer duration of follicular growth and that it is not affected by FSH starvation. Cows were allocated to short FSH (n=14), FSH starvation (n=13) and long FSH (n=13) groups. The first two groups were given eight doses of FSH, whereas the third group was given 14 doses of FSH, starting from the day of wave emergence (Day 0). A progesterone-releasing device (controlled internal drug release; CIDR) was placed intravaginally at the start of the experiment in all groups. The short FSH group was given prostaglandin (PG) F2α on Day 3, whereas the two other groups received PGF2α on Day 6. In all cows, the CIDR was removed at the time of PGF treatment; porcine (p) LH was given 24h after CIDR removal and cows were inseminated 24 and 36h later. Reproductive tracts were collected 4 days after insemination and ova and/or embryos were cultured for ≥6 days. The FSH starvation group had fewer ovulations (P=0.001), and ova and/or embryos (P<0.05). No difference in embryo quality was detected between long and short FSH groups at 7, 9 or 10 days after artificial insemination. In conclusion, oocyte competence was not altered by the duration of the follicular growth phase in superstimulated cows, whereas FSH starvation substantially reduced the ability of superstimulated follicles to ovulate.
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Dadarwal, D., F. Dias, G. Adams et J. Singh. « 287 EFFECT OF FOLLICULAR AGING ON THE ATP CONTENT AND DISTRIBUTION OF MITOCHONDRIA IN BOVINE OOCYTES ». Reproduction, Fertility and Development 27, no 1 (2015) : 232. http://dx.doi.org/10.1071/rdv27n1ab287.
Texte intégralRésumé :
Our objective was to determine how follicular aging affects the distribution and content of mitochondrial population and ATP in in vivo-matured bovine oocytes. We hypothesised that in vivo-matured bovine oocytes obtained from aged follicles (84 h of gonadotropin starvation) have altered mitochondrial distribution and decreased cytoplasmic ATP content compared to those obtained immediately at the end of a superstimulatory protocol (no starvation). Follicular waves were synchronized by ablation 5 to 8 d after ovulation and a CIDR device was given. Starting on the day of wave emergence (Day 0), short FSH and FSH starvation groups (n = 5 heifers each) were given 8 doses of FSH im over 4 d and the long FSH group (n = 4) was given 14 doses over 7 d. Two doses of PGF were given on Day 4 (short FSH) or Day 7 (FSH starvation and long FSH groups), the CIDR was removed, and LH was given 24 h after second PGF treatment. The ovaries were removed 24 h later by colpotomy and cumulus-oocyte-complexes (COC) were collected from follicles ≥8 mm. Denuded oocytes were either stained with Mitotracker Deep Red FM and imaged by confocal microscopy or processed for ATP assay. Mitochondria numbers were assessed by segmentation of 3D datasets. Proportions of COC within each grade were compared using Fischer's exact test, and ATP and mitochondrial data were compared by analysis of variance. Short and long FSH groups had a greater proportion of Grade 1 expanded COC than the FSH starvation group (P = 0.02). The ATP content of oocytes (from expanded COC) tended to be higher in the long FSH group than short FSH (P = 0.09), and the FSH starvation group was intermediate. The ATP content of oocytes from compact COC did not differ among groups (P = 0.49). The proportion of mitochondrial clusters was highest (P = 0.01) and the proportion of individual mitochondria was lowest (P = 0.01) in the FSH starvation group compared to short and long FSH groups. Mitochondria from the long FSH and FSH starvation groups had twice the relative intensity compared to the short FSH group (P < 0.01). In conclusion, follicular aging (FSH starvation) was associated with a decrease in oocyte morphologic grade and marked clustering of mitochondria, which may be a reflection of oxidative stress and atresia.
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Switzer, Amy, Daniel R. Brown et Sivaramesh Wigneshweraraj. « New insights into the adaptive transcriptional response to nitrogen starvation in Escherichia coli ». Biochemical Society Transactions 46, no 6 (4 décembre 2018) : 1721–28. http://dx.doi.org/10.1042/bst20180502.
Texte intégralRésumé :
Bacterial adaptive responses to biotic and abiotic stresses often involve large-scale reprogramming of the transcriptome. Since nitrogen is an essential component of the bacterial cell, the transcriptional basis of the adaptive response to nitrogen starvation has been well studied. The adaptive response to N starvation in Escherichia coli is primarily a ‘scavenging response’, which results in the transcription of genes required for the transport and catabolism of nitrogenous compounds. However, recent genome-scale studies have begun to uncover and expand some of the intricate regulatory complexities that underpin the adaptive transcriptional response to nitrogen starvation in E. coli. The purpose of this review is to highlight some of these new developments.
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Vujovic, Predrag, Iva Lakic, Nebojsa Jasnic, Tanja Jevdjovic, Sinisa Ðurasevic, Esma Isenovic et Jelena Ðordjevic. « Time-dependent effects of starvation on pituitary, hypothalamic and serum prolactin levels in rats : Comparison to the galanin expression pattern ». Archives of Biological Sciences 68, no 1 (2016) : 117–23. http://dx.doi.org/10.2298/abs150525133v.
Texte intégralRésumé :
Given that both prolactin and galanin take part in the regulation of energy homeostasis and that galanin is localized within lactotrophs, this study was aimed at comparing the pituitary expression patterns of prolactin and galanin during different phases of metabolic response to starvation in adult Wistar male rats. Food was removed at the onset of the dark phase (6:00 pm) and the animals were deprived for 6, 12, 24 and 48 h. Each of the starved groups (n=6) was killed simultaneously with a group of ad libitum-fed rats (n=6), and the intrapituitary levels of prolactin and galanin were examined. Galanin expression in the hypothalamus and the circulating levels of prolactin were also assessed. Starvation induced a rise in the intrapituitary prolactin level (p<0.001), whereas the opposite trend was detected in the serum (p<0.05). The galanin pituitary level was initially increased (6, 12 h) (p<0.05), but as starvation progressed, it first reached (at 24 h) and ultimately fell below the level recorded in the ad libitum rats (at 48 h) (p<0.05). Both prolactin and galanin were elevated in the hypothalamus after 24- and 48-h starvation. The results show that the starvation-induced increase in the pituitary prolactin expression did not lead to the rise in prolactin circulating levels, but rather resulted in the elevation of the prolactin hypothalamic content. Furthermore, the results suggest that under the circumstances of disturbed energy homeostasis, galanin might be responsible for the augmented prolactin production, initially at the pituitary and subsequently at the hypothalamic level.
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Liu, X., I. M. M. Hegab, J. Su, X. Du, X. Fan, Q. Zhang, Y. Gao et H. Wang. « Effects of different durations of fasting/re-feeding bouts on growth, biochemical and histological changes in the digestive tract of Gansu golden trout (Oncorhynchus mykiss) ». Czech Journal of Animal Science 63, No. 10 (27 septembre 2018) : 389–98. http://dx.doi.org/10.17221/107/2017-cjas.
Texte intégralRésumé :
This study was conducted to explore the outcomes of starvation/re-feeding techniques on growth performance, liver antioxidant activities, and histological changes of the gastrointestinal organs of Gansu golden trout. A total of 225 juveniles were divided into 5 treatment groups; the control group (N<sub>0</sub>) was routinely fed every day while the other groups (N<sub>7</sub>, N<sub>14</sub>, N<sub>21</sub>, and N<sub>28</sub>) were starved for 7, 14, 21, and 28 days, respectively and after the starvation session, each group was re-fed for 28 days. Compensatory growth was statistically recorded in N<sub>14</sub>. Weight gain rate and feeding ratio were the highest in the N<sub>14</sub> group, while specific growth rate and feeding conversion ratio showed significant increases in the fish groups exposed to longer starvation periods. Liver antioxidant activities showed a significant increase and decrease in malondialdehyde and superoxide dismutase levels in N<sub>21</sub> and N<sub>28</sub>, respectively, which returned to normal levels after re-feeding. Stomach, intestine, and liver showed histological alterations in all groups and the severity was correlated with the fasting periods. Those changes were restored to a certain degree after feeding was resumed. The compensation by group N<sub>14</sub> presents potential for economic usefulness of the fasting/re-feeding strategy in Gansu golden trout.
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Laheng, Suardi, Fiansi Fiansi et Ambarwati Ambarwati. « EFEK PEMUASAAN DAN PAKAN FERMENTASI TERHADAP LAJU PERTUMBUHAN DAN FEED CONVERTION RATIO IKAN NILA (Oreochromis niloticus) ». Jurnal Akuakultur Rawa Indonesia 8, no 2 (10 décembre 2020) : 102–10. http://dx.doi.org/10.36706/jari.v8i2.11218.
Texte intégralRésumé :
The main fish farming activities at the enlargement stage require a feed cost of around 60% of the total production cost. Efforts that can be made to reduce the cost of feed are through the starvation and fermentation of feed. This study uses a Completely Randomized Design (CRD) which is 3 treatments and 3 replications. The treatments tried were treatment A = protein feed 31-33% without fermentation (daily feeding), treatment B = protein feed 21-23% fermentation,, (daily feeding), treatment C = protein feed 21-23% fermentation, (1 day starvation 1 day re-feeding), treatment D = protein feed 21-23% fermentation, (1 day starvation 2 days re-feeding), E treatment = protein feed 21-23% fermentation, n (1 day starvation 3 days re-feeding). The study was conducted in a walled pond which was sealed using a net (50 x 50 x 100 cm3), feeding 3 times a day. The results showed that the treatment E effectively suppressed the FCR value and offset the daily growth rate of Treatment A. In addition, treatment E has the same FCR value as treatments B, C, D but treatment E has a higher daily growth rate.Keywords: starvation, fermentation, growth, FCR
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Guan, Peizhu, Juan-José Ripoll, Renhou Wang, Lam Vuong, Lindsay J. Bailey-Steinitz, Dening Ye et Nigel M. Crawford. « Interacting TCP and NLP transcription factors control plant responses to nitrate availability ». Proceedings of the National Academy of Sciences 114, no 9 (15 février 2017) : 2419–24. http://dx.doi.org/10.1073/pnas.1615676114.
Texte intégralRésumé :
Plants have evolved adaptive strategies that involve transcriptional networks to cope with and survive environmental challenges. Key transcriptional regulators that mediate responses to environmental fluctuations in nitrate have been identified; however, little is known about how these regulators interact to orchestrate nitrogen (N) responses and cell-cycle regulation. Here we report that teosinte branched1/cycloidea/proliferating cell factor1-20 (TCP20) and NIN-like protein (NLP) transcription factors NLP6 and NLP7, which act as activators of nitrate assimilatory genes, bind to adjacent sites in the upstream promoter region of the nitrate reductase gene, NIA1, and physically interact under continuous nitrate and N-starvation conditions. Regions of these proteins necessary for these interactions were found to include the type I/II Phox and Bem1p (PB1) domains of NLP6&7, a protein-interaction module conserved in animals for nutrient signaling, and the histidine- and glutamine-rich domain of TCP20, which is conserved across plant species. Under N starvation, TCP20-NLP6&7 heterodimers accumulate in the nucleus, and this coincides with TCP20 and NLP6&7-dependent up-regulation of nitrate assimilation and signaling genes and down-regulation of the G2/M cell-cycle marker gene, CYCB1;1. TCP20 and NLP6&7 also support root meristem growth under N starvation. These findings provide insights into how plants coordinate responses to nitrate availability, linking nitrate assimilation and signaling with cell-cycle progression.
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Bollmann, Annette, Ingo Schmidt, Aaron M. Saunders et Mette H. Nicolaisen. « Influence of Starvation on Potential Ammonia-Oxidizing Activity and amoA mRNA Levels of Nitrosospira briensis ». Applied and Environmental Microbiology 71, no 3 (mars 2005) : 1276–82. http://dx.doi.org/10.1128/aem.71.3.1276-1282.2005.
Texte intégralRésumé :
ABSTRACT The effect of short-term ammonia starvation on Nitrosospira briensis was investigated. The ammonia-oxidizing activity was determined in a concentrated cell suspension with a NOx biosensor. The apparent half-saturation constant [Km(app) ] value of the NH3 oxidation of N. briensis was 3 μM NH3 for cultures grown both in continuous and batch cultures as determined by a NOx biosensor. Cells grown on the wall of the vessel had a lower Km(app) value of 1.8 μM NH3. Nonstarving cultures of N. briensis showed potential ammonia-oxidizing activities of between 200 to 250 μM N h−1, and this activity decreased only slowly during starvation up to 10 days. Within 10 min after the addition of fresh NH4 +, 100% activity was regained. Parallel with activity measurements, amoA mRNA and 16S rRNA were investigated. No changes were observed in the 16S rRNA, but a relative decrease of amoA mRNA was observed during the starvation period. During resuscitation, an increase in amoA mRNA expression was detected simultaneously. The patterns of the soluble protein fraction of a 2-week-starved culture of N. briensis showed only small differences in comparison to a nonstarved control. From these results we conclude that N. briensis cells remain in a state allowing fast recovery of ammonia-oxidizing activity after addition of NH4 + to a starved culture. Maintaining cells in this kind of active state could be the survival strategy of ammonia-oxidizing bacteria in nature under fluctuating NH4 + availability.
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Gallaher, Brian W., Bernhard H. Breier, Mark H. Oliver, Jane E. Harding et Peter D. Gluckman. « Ontogenic differences in the nutritional regulation of circulating IGF binding proteins in sheep plasma ». Acta Endocrinologica 126, no 1 (janvier 1992) : 49–54. http://dx.doi.org/10.1530/acta.0.1260049.
Texte intégralRésumé :
Well-fed castrated male sheep (N= 3) and 125 days gestation pregnant ewes (N = 6) with chronically catheterized fetuses were fasted for 72 h. Insulin-like growth factor-binding protein (IGFBP) levels in fed and starved fetal, maternal and castrated male sheep plasma were measured using ligand blot analysis. IGFBPs in adult and fetal sheep differed in distribution both before and after 72 h starvation. IGFBP-3 was the major postnatal binding protein, while in the fetus IGFBP-2, IGFBP-3 and the circulating IGF type 2 receptor fragment each contributed 2 5–30% of total IGF binding capacity. After starvation, total IGF binding capacity and IGFBP-3 fell in plasma of maternal and castrated male sheep (p<0.05). Total IGF binding capacity rose with starvation in fetal plasma (p <0.05) as a result of an increase in IGFBP-1 (p< 0.01) and IGFBP-2 (p<0.05). The different nutritional control of the IGFBPs in the fetus and the adult may reflect ontogenic differences in the regulation and function of circulating IGFs and their binding proteins.
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Ardawi, M. S. M., et E. A. Newsholme. « Fuel utilization in colonocytes of the rat ». Biochemical Journal 231, no 3 (1 novembre 1985) : 713–19. http://dx.doi.org/10.1042/bj2310713.
Texte intégralRésumé :
In incubated colonocytes isolated from rat colons, the rates of utilization O2, glucose or glutamine were linear with respect to time for over 30 min, and the concentrations of adenine nucleotides plus the ATP/ADP or ATP/AMP concentration ratios remained approximately constant for 30 min. Glutamine, n-butyrate or ketone bodies were the only substrates that caused increases in O2 consumption by isolated incubated colonocytes. The maximum activity of hexokinase in colonic mucosa is similar to that of 6-phosphofructokinase. Starvation of the donor animal decreased the activities of hexokinase and 6-phosphofructokinase, whereas it increased those of glucose-6-phosphatase and fructose-bisphosphatase. Isolated incubated colonocytes utilized glucose at about 6.8 mumol/min per g dry wt., with lactate accounting for 83% of glucose removed. These rates were not affected by the addition of glutamine, acetoacetate or n-butyrate, and starvation of the donor animal. Isolated incubated colonocytes utilized glutamine at about 5.5 mumol/min per g dry wt., which is about 21% of the maximum activity of glutaminase. The major end-products of glutamine metabolism were glutamate, aspartate, alanine and ammonia. Starvation of the donor animal decreased the rate of glutamine utilization by colonocytes, which is accompanied by a decrease in glutamate formation and in the maximum activity of glutaminase. Isolated incubated colonocytes utilized acetoacetate at about 3.5 mumol/min per g dry wt. This rate was not markedly affected by addition of glucose or by starvation of the donor animal. When colonocytes were incubated with n-butyrate, both acetoacetate and 3-hydroxybutyrate were formed, with the latter accounting for only about 19% of total ketones produced.
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Ahlman, BO, Kerstin Andersson, Carl-Eric Leijonmarck, Olle Ljungqvist, Lennart Hedenborg et JAN Wernerman. « Short-Term Starvation Alters the Free Amino Acid Content of the Human Intestinal Mucosa ». Clinical Science 86, no 6 (1 juin 1994) : 653–62. http://dx.doi.org/10.1042/cs0860653.
Texte intégralRésumé :
1. The effects of short-term starvation and refeeding on the free amino acid concentrations of the intestinal mucosa were characterized in male subjects (n = 6), using endoscopically obtained biopsy specimens from the duodenum and from all four segments of the colon. 2. The alterations in the amino acid concentrations in response to short-term starvation were overall uniform in both duodenal and colonic mucosa as well as in plasma. Most amino acids decreased, whereas branched-chain amino acids increased. 3. In the colon, glutamic acid and glutamine decreased during the starvation period, whereas they remained unaltered in the duodenum. This was the major difference in response to short-term starvation between the amino acid concentrations in the intestinal mucosa of the duodenum and colon. 4. Refeeding for 3 days normalized the amino acid concentrations except for glutamic acid, asparagine and histidine, which remained low in the colon, and threonine, which showed an overshoot in both parts of the intestine. 5. The changes in mucosal amino acid concentrations seen in response to starvation and refeeding were uniform in the four segments of the colon. This suggests that sampling from the rectum/sigmoid colon will give representative values for the free amino acid concentrations of the entire large intestine.
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Janssen, Jorijn H., Jacco Spoelder, Jasper J. Koehorst, Peter J. Schaap, René H. Wijffels et Maria J. Barbosa. « Time-dependent transcriptome profile of genes involved in triacylglycerol (TAG) and polyunsaturated fatty acid synthesis in Nannochloropsis gaditana during nitrogen starvation ». Journal of Applied Phycology 32, no 2 (8 janvier 2020) : 1153–64. http://dx.doi.org/10.1007/s10811-019-02021-2.
Texte intégralRésumé :
AbstractIn this research, the gene expression of genes involved in lipid metabolism of the eustigmatophyte alga Nannochloropsis gaditana was measured by transcriptomic data. This microalga can be used as a source of triacylglycerol (TAG) and the omega-3 fatty acid eicosapentaenoic acid (EPA). Insight in TAG and EPA production and regulation are needed to improve their productivity. Nitrogen starvation induces TAG accumulation in N. gaditana. Previous research showed that during nitrogen starvation, EPA was translocated from the polar lipids to TAG and de novo synthesized in N. gaditana. Therefore, the expression levels of genes involved in fatty acid translocation and de novo TAG synthesis were measured. Furthermore, the genes involved in de novo EPA synthesis such as elongases and desaturases were studied. The expression levels were measured during the first hours of nitrogen starvation and the subsequent period of 14 days. One phospholipid:diacylglycerol acyltransferase (PDAT) gene involved in translocation of fatty acids from membrane lipids to TAG was upregulated. In addition, several lipases were upregulated, suggesting that these enzymes might be responsible for the translocation of EPA to TAG. Most desaturases and elongases involved in de novo EPA synthesis were downregulated during nitrogen starvation, except for Δ9 desaturase which was upregulated. This upregulation correlates with the increase in oleic acid. Due to the presence of many hypothetical genes, improvement in annotation is needed to increase our understanding of these pathways and their regulation.
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Xu, Keqiang, Xiaqing Wu, Yan Cheng, Jiao Yan, Yanlin Feng, Rui Chen, Runxiao Zheng et al. « A biomimetic nanoenzyme for starvation therapy enhanced photothermal and chemodynamic tumor therapy ». Nanoscale 12, no 45 (2020) : 23159–65. http://dx.doi.org/10.1039/d0nr05097k.
Texte intégralRésumé :
Glucose oxidase decorated N-doped carbon nanoparticles have been designed as a biomimetic nanoenzyme, which present prominent synergistic effects of starvation therapy enhancing photothermal therapy and chemodynamic therapy against tumors.
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Wei, Xueming, et Wolfgang D. Bauer. « Starvation-Induced Changes in Motility, Chemotaxis, and Flagellation of Rhizobium meliloti ». Applied and Environmental Microbiology 64, no 5 (1 mai 1998) : 1708–14. http://dx.doi.org/10.1128/aem.64.5.1708-1714.1998.
Texte intégralRésumé :
ABSTRACT The changes in motility, chemotactic responsiveness, and flagellation of Rhizobium meliloti RMB7201, L5-30, and JJ1c10 were analyzed after transfer of the bacteria to buffer with no available C, N, or phosphate. Cells of these three strains remained viable for weeks after transfer to starvation buffer (SB) but lost all motility within just 8 to 72 h after transfer to SB. The rates of motility loss differed by severalfold among the strains. Each strain showed a transient, two- to sixfold increase in chemotactic responsiveness toward glutamine within a few hours after transfer to SB, even though motility dropped substantially during the same period. Strains L5-30 and JJ1c10 also showed increased responsiveness to the nonmetabolizable chemoattractant cycloleucine. Cycloleucine partially restored the motility of starving cells when added after transfer and prevented the loss of motility when included in the SB used for initial suspension of the cells. Thus, interactions between chemoattractants and their receptors appear to affect the regulation of motility in response to starvation independently of nutrient or energy source availability. Electron microscopic observations revealed that R. meliloti cells lost flagella and flagellar integrity during starvation, but not as fast, nor to such a great extent, as the cells lost motility. Even after prolonged starvation, when none of the cells were actively motile, about one-third to one-half of the initially flagellated cells retained some flagella. Inactivation of flagellar motors therefore appears to be a rapid and important response ofR. meliloti to starvation conditions. Flagellar-motor inactivation was at least partially reversible by addition of either cycloleucine or glucose. During starvation, some cells appeared to retain normal flagellation, normal motor activity, or both for relatively long periods while other cells rapidly lost flagella, motor activity, or both, indicating that starvation-induced regulation of motility may proceed differently in various cell subpopulations.
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Riekhof, Wayne R., Surabhi Naik, Helmut Bertrand, Christoph Benning et Dennis R. Voelker. « Phosphate Starvation in Fungi Induces the Replacement of Phosphatidylcholine with the Phosphorus-Free Betaine Lipid Diacylglyceryl-N,N,N-Trimethylhomoserine ». Eukaryotic Cell 13, no 6 (11 avril 2014) : 749–57. http://dx.doi.org/10.1128/ec.00004-14.
Texte intégralRésumé :
ABSTRACTDiacylglyceryl-N,N,N-trimethylhomoserine (DGTS) is a phosphorus-free betaine-lipid analog of phosphatidylcholine (PtdCho) synthesized by many soil bacteria, algae, and nonvascular plants. Synthesis of DGTS and other phosphorus-free lipids in bacteria occurs in response to phosphorus (P) deprivation and results in the replacement of phospholipids by nonphosphorous lipids. The genes encoding DGTS biosynthetic enzymes have previously been identified and characterized in bacteria and the algaChlamydomonas reinhardtii. We now report that many fungal genomes, including those of plant and animal pathogens, encode the enzymatic machinery for DGTS biosynthesis, and that fungi synthesize DGTS during P limitation. This finding demonstrates that replacement of phospholipids by nonphosphorous lipids is a strategy used in divergent eukaryotic lineages for the conservation of P under P-limiting conditions. Mutants ofNeurospora crassawere used to show that DGTS synthase encoded by theBTA1gene is solely responsible for DGTS biosynthesis and is under the control of the fungal phosphorus deprivation regulon, mediated by the NUC-1/Pho4p transcription factor. Furthermore, we describe the rational reengineering of lipid metabolism in the yeastSaccharomyces cerevisiae, such that PtdCho is completely replaced by DGTS, and demonstrate that essential processes of membrane biogenesis and organelle assembly are functional and support growth in the engineered strain.
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Ren, Yuanyuan, Han Sun, Jinquan Deng, Yue Zhang, Yuelian Li, Junchao Huang et Feng Chen. « Coordinating Carbon Metabolism and Cell Cycle of Chlamydomonasreinhardtii with Light Strategies under Nitrogen Recovery ». Microorganisms 9, no 12 (30 novembre 2021) : 2480. http://dx.doi.org/10.3390/microorganisms9122480.
Texte intégralRésumé :
Nutrient supplementation is common in microalgae cultivation to enhance the accumulation of biomass and biofunctional products, while the recovery mechanism from nutrient starvation is less investigated. In this study, the influence of remodeled carbon metabolism on cell cycle progression was explored by using different light wavelengths under N-repletion and N-recovery. The results suggested that blue light enhanced cell enlargement and red light promoted cell division under N-repletion. On the contrary, blue light promoted cell division by stimulating cell cycle progression under N-recovery. This interesting phenomenon was ascribed to different carbon metabolisms under N-repletion and N-recovery. Blue light promoted the recovery of photosystem II and redirected carbon skeletons into proteins under N-recovery, which potentially accelerated cell recovery and cell cycle progression. Although red light also facilitated the recovery of photosystem II, it mitigated the degradation of polysaccharide and then arrested almost all the cells in the G1 phase. By converting light wavelengths at the 12 h of N-recovery with blue light, red and white lights were proved to increase biomass concentration better than continuous blue light. These results revealed different mechanisms of cell metabolism of Chlamydomonas reinhardtii during N-recovery and could be applied to enhance cell vitality of microalgae from nutrient starvation and boost biomass production.
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Hervant, F., J. Mathieu et H. Barre. « Comparative study on the metabolic responses of subterranean and surface-dwelling amphipods to long-term starvation and subsequent refeeding ». Journal of Experimental Biology 202, no 24 (15 décembre 1999) : 3587–95. http://dx.doi.org/10.1242/jeb.202.24.3587.
Texte intégralRésumé :
The effects of long-term starvation and subsequent refeeding on intermediary and energy metabolism were investigated in two subterranean aquatic crustaceans, Niphargus rhenorhodanensis and Niphargus virei, and in a morphologically similar surface-dwelling species, Gammarus fossarum. The metabolic response to prolonged food deprivation was monophasic in G. fossarum, showing an immediate, linear and large decline in all of the energy reserves. In contrast, both subterranean organisms displayed successive periods of glucidic, proteo-glucidic then lipidic-dominant catabolism during food deprivation. In both subterranean species, lipids (51 % of the energy consumed during a 180-day starvation period) and proteins (44 %) were the most metabolized substrates in terms of total energy, whereas glycogen (5 %) contributed little energy. G. fossarum displayed a different energetic strategy: proteins comprised 56 % of the energy losses during a 28-day starvation period, total lipids some 39 % and glycogen reserves only 5 %. We propose an energy strategy for food-limited subterranean crustaceans involving the possession of (1) higher amounts of stored arginine phosphate, triglycerides and glycogen and (2) lower utilization rates of stored metabolites than G. fossarum and numerous other surface-dwelling crustaceans, making the fueling of food deprivation possible for a longer time. In addition, these species had a faster and more efficient assimilation of available nutrients during recovery from food deprivation, enabling preparation for a new nutritional stress. These specific adaptive responses might be considered, for N. virei and N. rhenorhodanensis, as an efficient energy-saving strategy for an environment where extended starvation periods alternate with sporadic feeding events, therefore improving their competitive advantages.
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Oguchi, Mai E., Koki Okuyama, Yuta Homma et Mitsunori Fukuda. « A comprehensive analysis of Rab GTPases reveals a role for Rab34 in serum starvation-induced primary ciliogenesis ». Journal of Biological Chemistry 295, no 36 (15 juillet 2020) : 12674–85. http://dx.doi.org/10.1074/jbc.ra119.012233.
Texte intégralRésumé :
Primary cilia are sensors of chemical and mechanical signals in the extracellular environment. The formation of primary cilia (i.e. ciliogenesis) requires dynamic membrane trafficking events, and several Rab small GTPases, key regulators of membrane trafficking, have recently been reported to participate in ciliogenesis. However, the precise mechanisms of Rab-mediated membrane trafficking during ciliogenesis remain largely unknown. In the present study, we used a collection of siRNAs against 62 human Rabs to perform a comprehensive knockdown screening for Rabs that regulate serum starvation-induced ciliogenesis in human telomerase reverse transcriptase retinal pigment epithelium 1 (hTERT-RPE1) cells and succeeded in identifying Rab34 as an essential Rab. Knockout (KO) of Rab34, but not of Rabs previously reported to regulate ciliogenesis (e.g. Rab8 and Rab10) in hTERT-RPE1 cells, drastically impaired serum starvation-induced ciliogenesis. Rab34 was also required for serum starvation-induced ciliogenesis in NIH/3T3 cells and MCF10A cells but not for ciliogenesis in Madin-Darby canine kidney (MDCK)-II cysts. We then attempted to identify a specific region(s) of Rab34 that is essential for ciliogenesis by performing deletion and mutation analyses of Rab34. Unexpectedly, instead of a specific sequence in the switch II region, which is generally important for recognizing effector proteins (e.g. Rab interacting lysosomal protein [RILP]), a unique long N-terminal region of Rab34 before the conserved GTPase domain was found to be essential. These findings suggest that Rab34 is an atypical Rab that regulates serum starvation-induced ciliogenesis through its unique N-terminal region.
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Ghillebert, Ruben, Erwin Swinnen, Pepijn De Snijder, Bart Smets et Joris Winderickx. « Differential roles for the low-affinity phosphate transporters Pho87 and Pho90 in Saccharomyces cerevisiae ». Biochemical Journal 434, no 2 (11 février 2011) : 243–51. http://dx.doi.org/10.1042/bj20101118.
Texte intégralRésumé :
When starved of Pi, yeast cells activate the PHO signalling pathway, wherein the Pho4 transcription factor mediates expression of genes involved in Pi acquisition, such as PHO84, encoding the high-affinity H+/Pi symporter. In contrast, transcription of PHO87 and PHO90, encoding the low-affinity H+/Pi transport system, is independent of phosphate status. In the present work, we reveal that, upon Pi starvation, these low-affinity Pi transporters are endocytosed and targeted to the vacuole. For Pho87, this process strictly depends on SPL2, another Pho4-dependent gene that encodes a protein known to interact with the N-terminal SPX domain of the transporter. In contrast, the vacuolar targeting of Pho90 upon Pi starvation is independent of both Pho4 and Spl2, although it still requires its SPX domain. Furthermore, both Pho87 and Pho90 are also targeted to the vacuole upon carbon-source starvation or upon treatment with rapamycin, which mimics nitrogen starvation, but although these responses are independent of PHO pathway signalling, they again require the N-terminal SPX domain of the transporters. These observations suggest that other SPX-interacting proteins must be involved. In addition, we show that Pho90 is the most important Pi transporter under high Pi conditions in the absence of a high-affinity Pi-transport system. Taken together, our results illustrate that Pho87 and Pho90 represent non-redundant Pi transporters, which are tuned by the integration of multiple nutrient signalling mechanisms in order to adjust Pi-transport capacity to the general nutritional status of the environment.
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Shen, J. W., J. R. Subjeck, R. B. Lock et W. E. Ross. « Depletion of topoisomerase II in isolated nuclei during a glucose-regulated stress response ». Molecular and Cellular Biology 9, no 8 (août 1989) : 3284–91. http://dx.doi.org/10.1128/mcb.9.8.3284-3291.1989.
Texte intégralRésumé :
Conditions, such as anoxia or glucose starvation, which induce the glucose-regulated set of stress proteins also lead to resistance to adriamycin (J. Shen, C. Hughes, C. Chao, J. Cai, C. Bartels, T. Gessner, and J. Subjeck, Proc. Natl. Acad. Sci. USA 84:3278-3282, 1987) and etoposide. We report here that chronic anoxia, glucose starvation, 2-deoxyglucose, the calcium ionophore A23187, glucosamine, ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), and tunicamycin (all specific inducers of the glucose regulated system) lead to a rapid and selective depletion of topoisomerase II from isolated nuclei of Chinese hamster ovary cells. This effect precedes a decline in tritiated thymidine incorporation and a redistribution of cells from S into G1/G0. The depletion of the enzyme is not accompanied by a decline in mRNA levels. We have also examined the mutant Chinese hamster K12 cell line which is temperature sensitive for expression of glucose-regulated proteins. When nuclei were isolated from K12 cells incubated at the nonpermissive temperature, a loss of topoisomerase II was again observed in congruence with the expression of stress proteins and cellular resistance to etoposide. These changes were not obtained in parental Wg1A cells incubated at the same temperature. These studies indicate that topoisomerase II is highly sensitive to glucose-regulated stresses and that its depletion from the nucleus, with the associated changes in cell cycle parameters, may represent general characteristics of the glucose-regulated state. Since anoxia and glucose starvation can occur during tumor development, this pathway for expression of drug resistance may have clinical ramifications.
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Shen, J. W., J. R. Subjeck, R. B. Lock et W. E. Ross. « Depletion of topoisomerase II in isolated nuclei during a glucose-regulated stress response. » Molecular and Cellular Biology 9, no 8 (août 1989) : 3284–91. http://dx.doi.org/10.1128/mcb.9.8.3284.
Texte intégralRésumé :
Conditions, such as anoxia or glucose starvation, which induce the glucose-regulated set of stress proteins also lead to resistance to adriamycin (J. Shen, C. Hughes, C. Chao, J. Cai, C. Bartels, T. Gessner, and J. Subjeck, Proc. Natl. Acad. Sci. USA 84:3278-3282, 1987) and etoposide. We report here that chronic anoxia, glucose starvation, 2-deoxyglucose, the calcium ionophore A23187, glucosamine, ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), and tunicamycin (all specific inducers of the glucose regulated system) lead to a rapid and selective depletion of topoisomerase II from isolated nuclei of Chinese hamster ovary cells. This effect precedes a decline in tritiated thymidine incorporation and a redistribution of cells from S into G1/G0. The depletion of the enzyme is not accompanied by a decline in mRNA levels. We have also examined the mutant Chinese hamster K12 cell line which is temperature sensitive for expression of glucose-regulated proteins. When nuclei were isolated from K12 cells incubated at the nonpermissive temperature, a loss of topoisomerase II was again observed in congruence with the expression of stress proteins and cellular resistance to etoposide. These changes were not obtained in parental Wg1A cells incubated at the same temperature. These studies indicate that topoisomerase II is highly sensitive to glucose-regulated stresses and that its depletion from the nucleus, with the associated changes in cell cycle parameters, may represent general characteristics of the glucose-regulated state. Since anoxia and glucose starvation can occur during tumor development, this pathway for expression of drug resistance may have clinical ramifications.
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Vigo-Trauco, Gabriela, Rony Garcia-Anleu et Donald J. Brightsmith. « Increasing Survival of Wild Macaw Chicks Using Foster Parents and Supplemental Feeding ». Diversity 13, no 3 (12 mars 2021) : 121. http://dx.doi.org/10.3390/d13030121.
Texte intégralRésumé :
The use of foster parents has great potential to help the recovery of highly endangered bird species. However, few studies have shown how to successfully use these techniques in wild populations. Scarlet Macaws (Ara macao macao) in Perú hatch 2–4 chicks per nest but about 24% of all chicks die of starvation and on average just 1.4 of them fledge per successful nest. In this study we develop and test new techniques to increase survival of wild Scarlet Macaw chicks by reducing chick starvation. We hypothesized that using foster parents would increase the survival of chicks at risk of starvation and increase overall reproductive success. Our results show that all relocated macaw chicks were successfully accepted by their foster parents (n = 28 chicks over 3 consecutive breeding seasons) and 89% of the relocated chicks fledged. Overall, we increased fledging success per available nest from 17% (2000 to 2016 average) to 25% (2017 to 2019) and decreased chick death by starvation from 19% to 4%. These findings show that the macaw foster parents technique and post relocation supplemental feeding provide a promising management tool to aid wild parrot population recovery in areas with low reproductive success.