The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in controlling several aspects of immune responses, including the activation and differentiation of specific T ...cell subsets and antigen-presenting cells, thought to be relevant in the context of experimental Trypanosoma cruzi infection. The relevance of AhR for the outcome of T. cruzi infection is not known and was investigated here. We infected wild-type (WT) mice and AhR knockout (AhR KO) mice with T. cruzi (Y strain) and determined levels of parasitemia, myocardial inflammation and fibrosis, expression of AhR/cytokines/suppressor of cytokine signaling (SOCS) (spleen/heart), and production of nitric oxide (NO), reactive oxygen species (ROS), and peroxynitrite (ONOO(-)) (spleen). AhR expression was increased in the heart of infected WT mice. Infected AhR KO mice displayed significantly reduced parasitemia, inflammation, and fibrosis of the myocardium. This was associated with an anticipated increased immune response characterized by increased levels of inflammatory cytokines and reduced expression of SOCS2 and SOCS3 in the heart. In vitro, AhR deficiency caused impairment in parasite replication and decreased levels of ROS production. In conclusion, AhR influences the development of murine Chagas disease by modulating ROS production and regulating the expression of key physiological regulators of inflammation, SOCS1 to -3, associated with the production of cytokines during experimental T. cruzi infection.
To identify genomic regions involved in the regulation of fundamental physiological processes such as photosynthesis and respiration, a population of Solanum pennellii introgression lines was ...analyzed. We determined phenotypes for physiological, metabolic, and growth related traits, including gas exchange and chlorophyll fluorescence parameters. Data analysis allowed the identification of 208 physiological and metabolic quantitative trait loci with 33 of these being associated to smaller intervals of the genomic regions, termed BINs. Eight BINs were identified that were associated with higher assimilation rates than the recurrent parent M82. Two and 10 genomic regions were related to shoot and root dry matter accumulation, respectively. Nine genomic regions were associated with starch levels, whereas 12 BINs were associated with the levels of other metabolites. Additionally, a comprehensive and detailed annotation of the genomic regions spanning these quantitative trait loci allowed us to identify 87 candidate genes that putatively control the investigated traits. We confirmed 8 of these at the level of variance in gene expression. Taken together, our results allowed the identification of candidate genes that most likely regulate photosynthesis, primary metabolism, and plant growth and as such provide new avenues for crop improvement.
In this manuscript, genomic regions involved in the regulation of physiological processes such as photosynthesis, respiration, and underlying traits were identified. To accomplish this objective, we used a population of 71 Solanum pennellii introgression lines in the genetic background of S. lycopersicum. We analyzed leaf metabolites and physiological parameters of this population and linked these traits to the different allelic variant harbored by each line across two independent harvests. Data analyses allowed identification of 67 physiological and metabolic quantitative trait loci. Eleven genomic regions involved in starch levels in addition to seven and 16 related to shoot and root dry matter, respectively, were detected. Additionally, a comprehensive and detailed annotation of these regions allowed to point out 87 candidate genes involved in regulation of the four investigated traits. Taken together, we present the largest study of photosynthetic and growth parameters in tomato plants to date. Our results allowed the identification of candidate genes for regulation of photosynthesis, primary metabolism and plant growth, and thus providing new avenues for crop improvement.
•Placenta’s capsaicin is connected with fluctuation in metabolism during fruit ripening.•Metabolite levels in both placenta and pericarp are uniformly stable across accessions during fruit ...development.•Accumulation of capsaicinoids in placenta tissues do not largely affect the levels of primary metabolites.
Fruit pungency is caused by the accumulation of capsaicinoids, secondary metabolites whose relation to primary metabolism remains unclear. We have selected ten geographically diverse accessions of Capsicum chinense Jacq with different pungency levels. A detailed metabolic profile was conducted in the fruit placenta and pericarp at 20, 45, and 60 days after anthesis aiming at increasing our understanding of the metabolic changes in these tissues across fruit development and their potential connection to capsaicin metabolism. Overall, despite the variation in fruit pungency among the ten accessions, the composition and metabolite levels in both placenta and pericarp were uniformly stable across accessions. Most of the metabolite variability occurred between the fruit developmental stages rather than among the accessions. Interestingly, different metabolite adjustments in the placenta were observed among pungent and non-pungent accessions, which seem to be related to differences in the genetic background. Furthermore, we observed high coordination between metabolites and capsaicin production in C. chinense fruits, suggesting that pungency in placenta is adjusted with primary metabolism.
Many studies have investigated the various genetic and environmental factors regulating cyanobacterial growth. Here, we investigated the growth and metabolism of Synechocystis sp. PCC 6803 under ...different nitrogen sources, light intensities, and CO₂ concentrations. Cells grown on urea showed the highest growth rates. However, for all conditions tested, the daily growth rates in batch cultures decreased steadily over time, and stationary phase was obtained with similar cell densities. Unexpectedly, metabolic and physiological analyses showed that growth rates during log phase were not controlled primarily by the availability of photoassimilates. Further physiological investigations indicated that nutrient limitation, quorum sensing, light quality, and light intensity (self-shading) were not the main factors responsible for the decrease in the growth rate and the onset of the stationary phase. Moreover, cell division rates in fed-batch cultures were positively correlated with the dilution rates. Hence, not only light, CO₂, and nutrients can affect growth but also a cell-cell interaction. Accordingly, we propose that cell-cell interaction may be a factor responsible for the gradual decrease of growth rates in batch cultures during log phase, culminating with the onset of stationary phase.
The rubber tree, Hevea brasiliensis, is a species native to the Brazilian Amazon region and it supplies almost all the world's natural rubber, a strategic raw material for a variety of products. One ...of the major challenges for developing rubber tree plantations is adapting the plant to biotic and abiotic stress. Transcriptome analysis is one of the main approaches for identifying the complete set of active genes in a cell or tissue for a specific developmental stage or physiological condition.
Here, we report on the sequencing, assembling, annotation and screening for molecular markers from a pool of H. brasiliensis tissues. A total of 17,166 contigs were successfully annotated. Then, 2,191 Single Nucleotide Variation (SNV) and 1.397 Simple Sequence Repeat (SSR) loci were discriminated from the sequences. From 306 putative, mainly non-synonymous SNVs located in CDS sequences, 191 were checked for their ability to characterize 23 Hevea genotypes by an allele-specific amplification technology. For 172 (90%), the nucleotide variation at the predicted genomic location was confirmed, thus validating the different steps from sequencing to the in silico detection of the SNVs.
This is the first study of the H. brasiliensis transcriptome, covering a wide range of tissues and organs, leading to the production of the first developed SNP markers. This process could be amplified to a larger set of in silico detected SNVs in expressed genes in order to increase the marker density in available and future genetic maps. The results obtained in this study will contribute to the H. brasiliensis genetic breeding program focused on improving of disease resistance and latex yield.
Main conclusion Collectively, the results presented improve upon the utility of an important genetic resource and attest to a complex genetic basis for differences in both leaf metabolism and fruit ...morphology between natural populations. Diversity of accessions within the same species provides an alternative method to identify physiological and metabolic traits that have large effects on growth regulation, biomass and fruit production. Here, we investigated physiological and metabolic traits as well as parameters related to plant growth and fruit production of 49 phenotypically diverse pepper accessions of Capsicum chinense grown ex situ under controlled conditions. Although single-trait analysis identified up to seven distinct groups of accessions, working with the whole data set by multivariate analyses allowed the separation of the 49 accessions in three clusters. Using all 23 measured parameters and data from the geographic origin for these accessions, positive correlations between the combined phenotypes and geographic origin were observed, supporting a robust pattern of isolation-by-distance. In addition, we found that fruit set was positively correlated with photosynthesis-related parameters, which, however, do not explain alone the differences in accession susceptibility to fruit abortion. Our results demonstrated that, although the accessions belong to the same species, they exhibit considerable natural intraspecific variation with respect to physiological and metabolic parameters, presenting diverse adaptation mechanisms and being a highly interesting source of information for plant breeders. This study also represents the first study combining photosynthetic, primary metabolism and growth parameters for Capsicum to date.
Although a considerable increase in our knowledge concerning the importance of metabolic adjustments to unfavorable growth conditions has been recently provided, relatively little is known about the ...adjustments which occur in response to fluctuation in environmental factors. Evaluating the metabolic adjustments occurring under changing environmental conditions thus offers a good opportunity to increase our current understanding of the crosstalk between the major pathways which are affected by such conditions. To this end, plants growing under normal conditions were transferred to different light and temperature conditions which were anticipated to affect （amongst other processes） the rates of photosynthesis and photorespiration and characterized at the physiological, molecular, and metabolic levels following this transition. Our results revealed similar behavior in response to both treatments and imply a tight connec- tivity of photorespiration with the major pathways of plant metabolism. They further highlight that the majority of the regulation of these pathways is not mediated at the level of transcription but that leaf metabolism is rather pre-poised to adapt to changes in these input parameters.
Nutrient limitation, self-shading, and quorum sensing are not major limiting factors for the growth of Synechocystis in batch cultures.
Many studies have investigated the various genetic and ...environmental factors regulating cyanobacterial growth. Here, we investigated the growth and metabolism of
Synechocystis
sp. PCC 6803 under different nitrogen sources, light intensities, and CO
2
concentrations. Cells grown on urea showed the highest growth rates. However, for all conditions tested, the daily growth rates in batch cultures decreased steadily over time, and stationary phase was obtained with similar cell densities. Unexpectedly, metabolic and physiological analyses showed that growth rates during log phase were not controlled primarily by the availability of photoassimilates. Further physiological investigations indicated that nutrient limitation, quorum sensing, light quality, and light intensity (self-shading) were not the main factors responsible for the decrease in the growth rate and the onset of the stationary phase. Moreover, cell division rates in fed-batch cultures were positively correlated with the dilution rates. Hence, not only light, CO
2
, and nutrients can affect growth but also a cell-cell interaction. Accordingly, we propose that cell-cell interaction may be a factor responsible for the gradual decrease of growth rates in batch cultures during log phase, culminating with the onset of stationary phase.
In this paper, we study the (geodesic) hull number of graphs. For any two vertices u,v∈V of a connected undirected graph G=(V,E), the closed interval Iu,v of u and v is the set of vertices that ...belong to some shortest (u,v)-path. For any S⊆V, let IS=⋃u,v∈SIu,v. A subset S⊆V is (geodesically) convex if IS=S. Given a subset S⊆V, the convex hull IhS of S is the smallest convex set that contains S. We say that S is a hull set of G if IhS=V. The size of a minimum hull set of G is the hull number of G, denoted by hn(G).
First, we show a polynomial-time algorithm to compute the hull number of any P5-free triangle-free graph. Then, we present four reduction rules based on vertices with the same neighborhood. We use these reduction rules to propose a fixed parameter tractable algorithm to compute the hull number of any graph G, where the parameter can be the size of a vertex cover of G or, more generally, its neighborhood diversity, and we also use these reductions to characterize the hull number of the lexicographic product of any two graphs.
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