Low-temperature acclimation related with developmental regulations of polyamines and ethylene metabolism in wheat recombinant inbred lines

Winter survival is determined by complicated developmental regulations enabling wheat to adjust their transcriptome and metabolome to develop low temperature (LT) tolerance. The aim of the study was to clarify the metabolic responses developmentally regulated in six F6 recombinant inbred lines from a cross between Pishtaz (spring parent) and Mironovskaya 808 (winter parent). Spring genotypes, including pishtaz, RILs 4006 and 4014 showed lower LT tolerance, PAs (except the spermin), GABA and proline contents and DPPH• scavenging capacity. In these genotypes, genes and enzymes involved in the pathways of PAs and GABA degradation and ethylene biosynthesis were more active than other genotypes. RILs 4012 and 4016 with short vernalization displayed higher tolerance and lower H2O2 content compared to Pishtaz. Strong vernalization requirements in winter and facultative genotypes (Mironovskaya 808 parent and RILs 4003 and 4005) results in up-regulation of the metabolites and genes involved in PAs and GABA biosynthesis pathways (particularly when vernalization fulfillment occurred) to establish high tolerance as compared to genotypes without vernalization requirement. LT tolerance in all genotypes significantly decreased after vernalization fulfillment in February. Results indicated that LT tolerance was partly validated from developmental regulation of PAs, GABA, and ethylene metabolism during venalization and LT acclimation.

Foliar application of selenium nanoparticles alleviates cadmium toxicity in maize (Zea mays L.) seedlings: Evidence on antioxidant, gene expression, and metabolomics analysis

The molecular and metabolic mechanisms of foliar selenium (Se) nanoparticles (SeNPs) application in mitigating cadmium (Cd) toxicity in crops have not been well studied. Herein, hydroponically cultured maize seedlings were exposed to Cd (20 μM) and treated without and with foliar SeNPs application. Effects of SeNPs on Cd transporter genes and plant metabolism were also explored. Results showed that compared to control plants without Cd exposure, Cd exposure decreased shoot height (16.8 %), root length (17.7 %), and fresh weight of root (24.2 %), stem (28.8 %), and foliar-applied leaves (Se-leaves) (15.0 %) via oxidative damage. Compared to Cd exposure alone, foliar SeNPs application at 20 mg/L (0.25 mg/plant) significantly alleviated the Cd toxicity by promoting photosynthesis and antioxidant capacity and fixing Cd in cell wall. Meanwhile, the mineral concentration of Ca (26.0 %), Fe (55.4 %), Mg (27.0 %), Na (28.6 %), and Zn (10.1 %) in Se-leaves was improved via foliar SeNPs application at 20 mg/L. QRT-PCR analysis further revealed that down- and up-regulation of the expression of ZmHMA2 and ZmHMA3 gene in Se-leaves contributed to reduced translocation of Cd in plants and enhanced Cd sequestration in the vacuole, respectively. Metabolomic results further indicated that metabolic pathways including carbohydrate metabolism, membrane transport, translation, amino acid metabolism, and energy metabolism were significantly affected by foliar SeNPs application. In conclusion, foliar SeNPs application at 20 mg/L could be a prospective strategy to mitigate Cd toxicity in maize.

Uncovering global lipid accumulation routes towards docosahexaenoic acid (DHA) production in Aurantiochytrium sp. SW1 using integrative proteomic analysis

Aurantiochytrium sp., a marine thraustochytrid possesses a remarkable ability to produce lipid rich in polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Although gene regulation underlying lipid biosynthesis has been previously reported, proteomic analysis is still limited. In this study, high DHA accumulating strain Aurantiochytrium sp. SW1 has been used as a study model to elucidate the alteration in proteome profile under different cultivation phases i.e. growth, nitrogen-limitation and lipid accumulation. Of the total of 5146 identified proteins, 852 proteins were differentially expressed proteins (DEPs). The largest number of DEPs (488 proteins) was found to be uniquely expressed between lipid accumulating phase and growth phase. Interestingly, there were up-regulated proteins involved in glycolysis, glycerolipid, carotenoid and glutathione metabolism which were preferable metabolic routes towards lipid accumulation and DHA production as well as cellular oxidative defence. Integrated proteomic and transcriptomic data were also conducted to comprehend the gene and protein regulation underlying the lipid and DHA biosynthesis. A significant up-regulation of acetyl-CoA synthetase was observed which suggests alternative route of acetate metabolism for acetyl-CoA producer. This study presents the holistic routes underlying lipid accumulation and DHA production in Aurantiochytrium sp. SW1 and other relevant thraustochytrid.

SW1

Aurantiochytrium sp. SW1, a marine thraustochytrid, has been regarded as a potential candidate as a docosahexaenoic acid (DHA) producer. Even though the genomics of Aurantiochytrium sp. are available, the metabolic responses at a systems level are largely unknown. Therefore, this study aimed to investigate the global metabolic responses to DHA production in Aurantiochytrium sp. through transcriptome and genome-scale network-driven analysis. Of a total of 13,505 genes, 2527 differentially expressed genes (DEGs) were identified in Aurantiochytrium sp., unravelling the transcriptional regulations behinds lipid and DHA accumulation. The highest number of DEG were found for pairwise comparison between growth phase and lipid accumulating phase where a total of 1435 genes were down-regulated with 869 genes being up-regulated. These uncovered several metabolic pathways that contributing in DHA and lipid accumulation including amino acid and acetate metabolism which involve in the generation of crucial precursors. Upon applying network-driven analysis, hydrogen sulphide was found as potential reporter metabolite that could be associated with the genes related to acetyl-CoA synthesis for DHA production. Our findings suggest that the transcriptional regulation of these pathways is a ubiquitous feature in response to specific cultivation phases during DHA overproduction in Aurantiochytrium sp. SW1.

Differential immune and metabolic responses underlie differences in the resistance of Siganus oramin and Trachinotus blochii to Cryptocaryon irritans infection

Numerous studies have demonstrated that Cryptocaryon irritans can efficiently propagate in golden pompano (Trachinotus blochii), especially under intensive high-density culture, which can lead to large-scale infection, bacterial invasion, and major economic losses. By contrast, Siganus oramin is less susceptible to C. irritans infection. Here, we artificially infected S. oramin and T. blochii with C. irritans. We then used RNA-seq to characterize the expression of genes in the gills of S. oramin and T. blochii at different times after infection, conducted bioinformatics analysis of relevant pathways, and compared the differentially expressed genes in the two species. The aim of this study was to enhance our understanding of host-parasite interactions to aid the development of effective prevention and treatment strategies for C. irritans. Infection with C. irritans induced the differential expression of a large number of genes in the gills of S. oramin, indicating that S. oramin may respond to C. irritans infection by modifying the expression of genes at the transcriptional level. Our research showed that the Toll-like receptor signaling pathway, Antigen processing and presentation, Complement and coagulation cascades, and Cytosolic DNA-sensing pathway are involved in the immune response of S. oramin and T. blochii to C. irritans infection. However, T. blochii has a weak ability to mobilize neutrophils to participate in defense against C. irritans infection and differs from S. oramin in its ability to induce specific immune responses. Because of gill tissue damage during infection, dissolved oxygen intake is reduced, which increases physiological and metabolic stress. The metabolic pathways of S. oramin and T. blochii significantly differed; specifically, the main pathways in S. oramin were related to glucose and lipid metabolism, and the main pathways in T. blochii were related to amino acid metabolism. This may reduce the efficiency of ATP biosynthesis in T. blochii and result in dysfunctional energy metabolism. Therefore, differential immune and metabolic responses underlie differences in the resistance of S. oramin and T. blochii to C. irritans.

Metabolic responses of Chinese perch (Siniperca chuatsi) to different levels of dietary carbohydrate

There are great differences in metabolic responses to different levels of carbohydrate among different carnivorous fish species. To explore metabolic responses of Chinese perch to moderate and high level of dietary carbohydrates, three diets containing 7.3% (LC), 17.5% (MC), and 27.5% (HC) of carbohydrates were provided to Chinese perch for 56 days. The results showed that MC and HC groups exhibited an increase in weight gain (WG) and hepatic glycogen content, and a decrease in feed conversion efficiency, compared with the LC group. The MC and HC groups also showed the increase in mRNA levels of phosphofructokinase and citrate synthase related to the aerobic oxidation pathway, which might be responsible for the increase in WG. Moreover, compared with the LC group, the HC group exhibited high levels of plasma indices (glucose, pyruvic acid, lactic acid, total triglyceride, total cholesterol, and low-density lipoprotein) and liver lipid resulting from the increased mRNA levels of fatty acid synthesis-related genes (ATP citrate lyase, acetyl-CoA carboxylase α, and fatty acid synthase), low level of crude protein caused by inhibition of TOR pathway, and liver damage induced by low antioxidant capacity and infiltration of inflammatory cells, but the MC group did not. The above results indicated that 17.5% dietary carbohydrate might be utilized effectively in Chinese perch and part carbohydrates were converted into glycogen to maintain glucose homeostasis; 27.5% dietary carbohydrate could not be fully utilized. The 27.5% carbohydrate diet induced the up-regulation of aerobic oxidation, glycogen synthesis, and fat synthesis pathways which might not be sufficient to maintain glucose homeostasis.

Divergent metabolomic profiles of cold-exposed mature and immature females of tropical versus temperate Drosophila species

Temperate species, contrary to their tropical counterparts, are exposed not only to thermally variable environments with low temperatures but also to long winters. Different selective pressures may have driven divergent physiological adaptations in closely related species with different biogeographic origins. To survive unfavourable winter conditions, Drosophila species in temperate areas generally undergo a period of reproductive dormancy, associated with a cold-induced cessation of oogenesis and metabolic reorganization. This work aims to compare cold tolerance and metabolic signatures of cold-exposed females exhibiting different reproductive maturity status (mature and immature females) of four Drosophila species from tropical vs. temperate origins. We expected that the capacity for delayed reproduction of immature females could result in the redirection of the energy-related metabolites to be utilized for surviving the cold season. To do so, we studied an array of 45 metabolites using quantitative target GC-MS profiling. Reproductively immature females of temperate species showed the lower CT_min and the faster chill coma recovery time (i.e. the most cold-tolerant group). Principal component analysis captured differences across species, but also between reproductive maturity states. Notably, temperate species exhibited significantly higher levels of glucose, alanine, and gluconolactone than tropical ones. As proline and glycerol showed higher abundances in immature females of temperate species compared to the levels exhibited by the rest of the groups, we reasoned that glucose and alanine could serve as intermediates in the synthesis of these compatible solutes. All in all, our findings suggest that cold-exposed females of temperate species accumulate energy-related and protective metabolites (e.g. glycerol and proline) while delaying reproduction, and that these metabolites are relevant to cold tolerance even at modest concentrations.

How does the mid-season coach change affect physical performance on top soccer players?

The aim of this study was to analyze the locomotion and metabolic responses of professional players in the top three competitive standards of Spanish soccer (First, Second and Second 'B' division) during the four weeks before and after dismissal the coach. Training and match load data were analyzed separately (n = 1189 events) by coach (dismissed coach and the new coach) and Wilcoxon-test was performed to compare data between coaches. In training, players covered longer distance in all speed ranges >14 km•h ^- 1 with the coach dismissed; medium (14-18 km•h ^- 1), high (18-21 km•h ^- 1), very-high (21-24 km•h ^- 1) and sprint running distance (>24 km•h ^- 1) (d = 0.53, 0.46, 0.58 and 0.54; respectively) on first division; and equivalent distance index and accelerations events (d = 0.63 and 0.50; respectively) on second division. Lower differences were found in matches, in which the dismissed coach showed higher equivalent distance index, accelerations and decelerations events (d = 0.69, 0.68 and 0.61; respectively) compared to the new coach in the second division. Therefore, the players covered longer high-intensity distance with the dismissed coach than the new coach in training, whilst a similar performance was found in the competition. These results suggest that the coach turnover at mid-season did no increase the players' physical performance either in training or in competition.

Effect of cold stress on polyamine metabolism and antioxidant responses in chickpea

Metabolic and genomic characteristics of polyamines (PAs) may be associated with the induction of cold tolerance (CT) responses in plants. Characteristics of PAs encoding genes in chickpea (Cicer arietinum L.) and their function under cold stress (CS) are currently unknown. In this study, the potential role of PAs along with the antioxidative defense systems were assessed in two chickpea genotypes (Sel96th11439, cold-tolerant and ILC533, cold-sensitive) under CS conditions. Six days after exposure to CS, the leaf H₂O₂ content and electrolyte leakage index increased in the sensitive genotype by 47.7 and 59 %, respectively, while these values decreased or remained unchanged, respectively, in the tolerant genotype. In tolerant genotype, the enhanced activity of superoxide dismutase (SOD) (by 50 %) was accompanied by unchanged activities of ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and catalase (CAT) as well as the accumulation of glutathione (GSH) (by 43 %) on the sixth day of CS. Higher levels of putrescine (Put) (322 %), spermidine (Spd) (45 %), spermine (Spm) (69 %) and the highest ratio of Put/(Spd + Spm) were observed in tolerant genotype compared to the sensitive one on the sixth day of CS. Gamma-aminobutyric acid (GABA) accumulation was 74 % higher in tolerant genotype compared to the sensitive one on the sixth day of CS. During CS, the activity of diamine oxidase (DAO) and polyamine oxidase (PAO) increased in tolerant (by 3.02- and 2.46-fold) and sensitive (by 2.51- and 2.8-fold) genotypes, respectively, in comparison with the respective non-stressed plants (normal conditions). The highest activity of DAO and PAO in the tolerant genotype was accompanied by PAs decomposition and a peak in GABA content on the sixth day of CS. The analysis of chickpea genome revealed the presence of five PAs biosynthetic genes, their chromosomal locations, and cis-regulatory elements. A significant increase in transcript levels of arginine decarboxylase (ADC) (24.26- and 7.96-fold), spermidine synthase 1 (SPDS1) (3.03- and 1.53-fold), SPDS2 (5.5- and 1.62-fold) and spermine synthase (SPMS) (3.92- and 1.65-fold) genes was detected in tolerant and sensitive genotypes, respectively, whereas the expression of ornithine decarboxylase (ODC) genes decreased significantly under CS conditions in both genotypes. Leaf chlorophyll and carotenoid contents exhibited declining trends in the sensitive genotype, while these photosynthetic pigments were stable in the tolerant genotype due to the superior performance of defensive processes under CS conditions. Overall, these results suggested the specific roles of putative PAs genes and PAs metabolism in development of effective CT responses in chickpea.

Postprandial effects of macronutrient composition meals on the metabolic responses and arterial stiffness indices of lean and obese male adults: a protocol of a pilot study

BACKGROUND

Prior studies have shown that meal composition may affect the metabolic responses and arterial stiffness indices, and these responses may be different in lean and obese adults. The primary objective of this study is to determine the feasibility of conducting a trial to compare the effect of three test meals in lean and obese men. Due to the lack of a comprehensive study that concurrently compares metabolic responses and vascular stiffness indices after receiving three different meals in lean and obese men, this pilot study will be conducted with a three-phase parallel design, aiming to investigate the effects of meal composition on the metabolic parameters and arterial stiffness indices of lean and obese adults.

METHODS

This pilot, a parallel clinical trial will be performed on 24 male adults aged 18-35 years since January 2021 and will continue until March 2021 who are disease-free and selected based on the inclusion and exclusion criteria at Mashhad University of Medical Sciences, Iran. The subjects will complete three interventions at a 1-week interval, including high carbohydrate (70% carbohydrates, 10% protein, 20% fat), high protein (30% protein, 50% carbohydrates, 20% fat), and high-fat meal (50% fat, 40% carbohydrates, 10% protein). Postprandial effects will be assessed within 360 min after each meal, including the energy expenditure component (resting energy expenditure, thermic effects of feeding, respiratory quotient, and substrate oxidation) and arterial stiffness indices (augmentation index and pulse wave velocity). In addition, blood sampling will be performed to measure glucose, insulin, free fatty acids, and lipid profile.

DISCUSSION

The differences in the postprandial responses can affect the metabolic and vascular parameters due to different meal compositions, thereby providing beneficial data for the establishment of new strategies in terms of nutritional education and metabolic/vascular improvement. Also, the results from this pilot study will inform intervention refinement and efficacy testing of the intervention in a larger randomized controlled trial.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials; code: IRCT20190818044552N1 ; registered on August 26, 2019.

Metabolic alterations in conventional and genetically modified soybean plants with GmDREB2A;2 FL and GmDREB2A;2 CA transcription factors during water deficit

Water deficit is one of the main abiotic stress that affects plant growth and productivity. The GmDREB2A;2 (Glyma14g06080) gene is an important transcription factor involved in regulating the plants' responses under water deficit. In previous studies, soybean plants overexpressing full-length (GmDREB2A;2 FL) and constitutively active (GmDREB2A;2 CA) forms of the GmDREB2A;2 gene, presented higher tolerance to water deficit when compared with the conventional cultivar BRS 283. Therefore, identifying the changes in metabolite profile in these tolerant genotypes can contribute to the understanding of the metabolic pathways involved in the tolerance mechanism. In this work, the metabolic changes in roots and leaves of genetically modified (GM) soybean plants subjected to water deficit were elucidated by 1H-NMR spectroscopy. Three events were analyzed, one containing the gene in FL form (GmDREB2A;2 FL) and two presenting its CA form (GmDREB2A;2 CA-1 and GmDREB2A;2 CA-2) and compared with the conventional cultivar BRS 283. The results indicated different responses between leaves and roots for all genotypes. Most of these metabolic variations were related to carbohydrate and amino acid pathways. BRS 283 stood out with higher accumulation of amino acids in leaves under water deficit. The results also showed that the events GmDREB2A;2 FL and GmDREB2A;2 CA-1 presented higher concentrations of β-glucose and fructose in leaves, whereas BRS 283 accumulated more sucrose and pinitol. In roots, the GM events accumulated higher β-glucose, fructose, asparagine and phenylalanine, when compared with the conventional cultivar. These insights can add information on how the transcription factor (TF) DREB2A acts in soybean plants triggering and controlling a network of complex responses to drought.

Increased flux through the TCA cycle enhances bacitracin production by Bacillus licheniformis DW2

The dodecapeptide antibiotic bacitracin, produced by several strains of Bacillus licheniformis and Bacillus subtilis, is widely used as an antibacterial animal feed additive. Several genetic strategies were explored to enhance its production. The availability of building block amino acids for bacitracin production was found to play an important role in its synthesis. In this study, the TCA cycle in the industrial strain B. licheniformis DW2 was strengthened by overexpression of the key enzymes citrate synthase and isocitrate dehydrogenase (ICDH). As the central metabolic pathway, the TCA cycle is a major source for energy supply and intermediates for anabolism. By enhancing flux through the TCA cycle, more energy and precursors were generated for amino acid biosynthesis and uptake, resulting in enlarged intracellular pool of bacitracin-containing amino acids for bacitracin production. This study unveiled the metabolic responses of the increased TCA cycle flux in B. licheniformis and provided a novel strategy for enhancing bacitracin production.

Effects of walking with hand-held weights on energy expenditure and excess postexercise oxygen consumption

Walking is not only important to assist in performing daily tasks, but also to gain cardiovascular benefits. Further research on walking is needed to examine the physiological responses to improve health and reduce the risks of cardiovascular disease. The purpose of this study was to compare the energy expenditure (EE) during and after walking exercise with versus without hand-held weights (HHW). Nineteen sedentary women (mean±standard deviation; age, 21±2.7 years, height, 163.1±6.3 cm; body mass, 66.6± 15.1 kg; body fat %, 30.6%± 7.43%; body mass index, 25.5± 5.7 kg/m²) volunteered walking with versus without 1.36 kg of HHW in two randomized sessions. The study consisted of 30 min of exercise followed b silent sitting for 30 min. The range of motion was set at elbow flexion at 90° while arms were alternated 30.48 cm forward and backward. 1% incline was set for the treadmill grade and speed was controlled to a moderate level of 40%–59% of heart rate reserve. During the 30-min exercise no significant differences were found between the conditions (P> 0.05). The physiological responses were significantly greater directly after exercise compared with baseline as determined from pairwise comparisons collapsed across conditions (P≤ 0.05). Walking with HHW was not substantial enough to raise EE beyond normal walking and led to an increased effort level. Additionally, the moderate intensity of walking was not enough to sustain EE at a surpassing level directly after the exercise.

Rates of hypoxia induction alter mechanisms of O2 uptake and the critical O2 tension of goldfish

The rate of hypoxia induction (RHI) is an important but overlooked dimension of environmental hypoxia that may affect an organism's survival. We hypothesized that, compared with rapid RHI, gradual RHI will afford an organism more time to alter plastic phenotypes associated with O₂ uptake and subsequently reduce the critical O₂ tension (P_crit) of the rate of O₂ uptake (Ṁ_O2 ). We investigated this by determining P_crit values for goldfish exposed to short (∼24 min), typical (∼84 min) and long (∼480 min) duration P_crit trials to represent different RHIs. Consistent with our predictions, long duration P_crit trials yielded significantly lower P_crit values (1.0-1.4 kPa) than short and typical duration trials, which did not differ (2.6±0.3 and 2.5±0.2 kPa, respectively). Parallel experiments revealed these time-related shifts in P_crit were associated with changes to aspects of the O₂ transport cascade that took place over the hypoxia exposures: gill surface areas and haemoglobin-O₂ binding affinities were significantly higher in fish exposed to gradual RHIs over 480 min than fish exposed to rapid RHIs over 60 min. Our results also revealed that the choice of respirometric technique (i.e. closed versus intermittent) does not affect P_crit or routine Ṁ_O2 , despite the significantly reduced water pH and elevated CO₂ and ammonia levels measured following closed-circuit P_crit trials of ∼90 min. Together, our results demonstrate that gradual RHIs result in alterations to physiological parameters that enhance O₂ uptake in hypoxic environments. An organism's innate P_crit is therefore most accurately determined using rapid RHIs (<90 min) so as to avoid the confounding effects of hypoxic acclimation.

Metabolic responses to intestine regeneration in sea cucumbers Apostichopus japonicus

Sea cucumbers are excellent models for studying organ regeneration due to their striking capacity to regenerate most of their viscera after evisceration. In this study, we applied NMR-based metabolomics to determine the metabolite changes that occur during the process of intestine regeneration in sea cucumbers. Partial least-squares discriminant analysis showed that there was significant differences in metabolism between regenerative intestines at 3, 7, and 14days post evisceration (dpe) and normal intestines. Changes in the concentration of 13 metabolites related to regeneration were observed and analyzed. These metabolites included leucine, isoleucine, valine, arginine, glutamate, hypotaurine, dimethylamine, N,N-dimethylglycine, betaine, taurine, inosine, homarine, and histidine. Three important genes (betaine-aldehyde dehydrogenase, betaine-homocysteine S-methyltransferase 1, and dimethylglycine dehydrogenase) were differentially expressed to regulate the levels of betaine and N,N-dimethylglycine during intestine regeneration. These results provide an important basis for studying regenerative mechanisms and developing regenerative matrixes.

Effects of whole-grain rye porridge with added inulin and wheat gluten on appetite, gut fermentation and postprandial glucose metabolism: a randomised, cross-over, breakfast study

Whole-grain rye foods reduce appetite, insulin and sometimes glucose responses. Increased gut fermentation and plant protein may mediate the effect. The aims of the present study were to investigate whether the appetite-suppressing effects of whole-grain rye porridge could be enhanced by replacing part of the rye with fermented dietary fibre and plant protein, and to explore the role of gut fermentation on appetite and metabolic responses over 8 h. We conducted a randomised, cross-over study using two rye porridges (40 and 55 g), three 40-g rye porridges with addition of inulin:gluten (9:3; 6:6; 3:9 g) and a refined wheat bread control (55 g), served as part of complete breakfasts. A standardised lunch and an ad libitum dinner were served 4 and 8 h later, respectively. Appetite, breath hydrogen and methane, glucose, insulin and glucagon-like peptide-1 (GLP-1) responses were measured over 8 h. Twenty-one healthy men and women, aged 23-60 years, with BMI of 21-33 kg/m2 participated in this study. Before lunch, the 55-g rye porridges lowered hunger by 20 % and desire to eat by 22 % and increased fullness by 29 % compared with wheat bread (P<0·05). Breath hydrogen increased proportionally to dietary fibre content (P<0·05). Plasma glucose after lunch was 6 % lower after the 55-g rye porridges compared with wheat bread (P<0·05) and correlated to breath hydrogen (P<0·001). No differences were observed in ad libitum food intake, insulin or GLP-1. We conclude that no further increase in satiety was observed when replacing part of the rye with inulin and gluten compared with plain rye porridges.