Respiratory Metabolism Research Articles

Dark accumulation of downstream glycolytic intermediates initiates robust photosynthesis in cyanobacteria.

Photosynthesis must maintain stability and robustness throughout fluctuating natural environments. In cyanobacteria, dark-to-light transition leads to drastic metabolic changes from dark respiratory metabolism to CO2 fixation through the Calvin-Benson-Bassham (CBB) cycle using energy and redox equivalents provided by photosynthetic electron transfer. Previous studies have shown that catabolic metabolism supports the smooth transition into CBB cycle metabolism. However, metabolic mechanisms for robust initiation of photosynthesis are poorly understood due to lack of dynamic metabolic characterizations of dark-to-light transitions. Here, we show rapid dynamic changes (on a time scale of seconds) in absolute metabolite concentrations and 13C tracer incorporation after strong or weak light irradiation in the cyanobacterium Synechocystis sp. PCC 6803. Integration of this data enabled estimation of time-resolved nonstationary metabolic flux underlying CBB cycle activation. This dynamic metabolic analysis indicated that downstream glycolytic intermediates, including phosphoglycerate and phosphoenolpyruvate, accumulate under dark conditions as major substrates for initial CO2 fixation. Compared with wild-type Synechocystis, significant decreases in the initial oxygen evolution rate were observed in 12 h dark preincubated mutants deficient in glycogen degradation or oxidative pentose phosphate pathways. Accordingly, the degree of decrease in the initial oxygen evolution rate was proportional to the accumulated pool size of glycolytic intermediates. These observations indicate that the accumulation of glycolytic intermediates is essential for efficient metabolism switching under fluctuating light environments.

Linalool against Hafnia alvei, its antibacterial mechanism revealed by metabolomic analyses

Linalool, a major component of aromatic plant essential oils, has an antibacterial effect against Hafnia alvei, which can induce food spoilage. In this study, we aimed to investigate the antibacterial effect and mechanism of linalool against H. alvei. Linalool treatment resulted in excessive reactive oxygen species (ROS) accumulation, which resulted in destruction of the cell membrane. According to the field emission scanning electron microscopy (FESEM) and flow cytometry (FCM) results, it was confirmed that the membrane structure of H. alvei was destroyed. Moreover, metabolomics analysis showed that there were 64 and 73 differentially expressed metabolites screened by mass spectrometry in positive and negative ion modes, respectively, suggesting that nucleic acid metabolism, the respiratory chain and energy metabolism were negatively affected by linalool. Biochemical validation confirmed that the activities of malate dehydrogenase (MDH), and succinate dehydrogenase (SDH) and respiratory metabolism were reduced after linalool treatment. It was therefore concluded that the cell membrane was damaged, nucleic acid metabolism was disturbed, and energy metabolism was reduced by inhibition of the respiratory chain and tricarboxylic acid (TCA) cycle. These results revealed the antibacterial mechanism of linalool against H. alvei, and support the use of linalool as a potential natural preservative to control H. alvei.

IDENTIFICATION OF CHANGES IN THE METABOLIC PROCESSES OF GERMINATION AND GROWTH OF MAIZE SEEDLINGS UNDER THE INFLUENCE OF HEAT STRESS AND THE USE OF REGLALG

Laboratory experiments were carried out to determine the effect of pretreatment of seeds of two hybrids of maize (Zea mays L.) with Reglalg and subsequent exposure to heat stress (HS) of 50°C for 30 min on seed germination, seedling growth and assessment of translocation of endosperm reserve substances for these processes. The results showed a positive effect of Reglalg on seed germination and seedling growth parameters, which were affected by HS conditions. The use of Reglalg to treat the seeds of maize hybrids before expose to HS, had a beneficial effect on the formation of seedling biomass due to an increase in the mass of endosperm translocated from seeds to these processes under the conditions of stress. Also, the use of Reglalg in seed pretreatment favored the decrease in endosperm mass consumed for cellular metabolism respiration under HS.

The combined effects of temperature and salinity on the digestion and respiration metabolism of Pinctada fucata

The combined effects of temperature and salinity on the digestion and respiration metabolism of Pinctada fucata were evaluated via response surface methodology and box-benhnken design under laboratory condition. Results indicated that the primary and secondary effects of salinity and temperature had significant effects on amylase (AMS) of P. fucata (P < 0.05)., The digestive enzyme reached the maximum activity when temperature was 26 °C. The AMS and trypsin (TRYP) increased at first, and then decreased with increasing temperature. The Lipase (LPS) was positively correlated with either salinity or temperature. Salinity had no significant effect on TRYP as a primary effect (P > 0.05), but had a significant effect on TRYP as a secondary effect (P < 0.01). These effects were completely opposite to the effect of temperature on pepsin (PEP) as primary and secondary effects. The combined effects of salinity and temperature on AMS, TRYP and PEP were significant (P < 0.01), but had no significant effect on LPS (P > 0.05). The primary, secondary and interaction effects of salinity had significant effects on NKA (Na+-K+-ATPase) of P. fucata (P < 0.05), and NKA presented a U-shaped distribution with increasing salinity. The quadratic and interactive effects of temperature had a significant effect on AKP (P < 0.05), and AKP showed a U-shaped distribution with increasing temperature. Lactate dehydrogenase (LDH) activity decreased at first, and then increased when temperature and salinity changed from 20 to 30 °C and 23–33 ‰, respectively. The expression of GPX gene affected by temperature in gills may be delayed compared with that in hepatopancreas, and its expression is tissue-specific. The appropriate digestion and respiratory metabolism index models were established under the combined temperature and salinity conditions. The optimization results showed that the optimal combination of temperature and salinity was 26.288 °C/28.272‰. The desirability was 0.832. Results from the present study will provide a theoretical reference for shellfish culture affected by environmental interactions and the establishment of related index models.

Genome-Wide Identification and Expression Profiling of Aconitase Gene Family Members Reveals Their Roles in Plant Development and Adaptation to Diverse Stress in Triticum aestivum L.

Global warming is a serious threat to food security and severely affects plant growth, developmental processes, and, eventually, crop productivity. Respiratory metabolism plays a critical role in the adaptation of diverse stress in plants. Aconitase (ACO) is the main enzyme, which catalyzes the revocable isomerization of citrate to isocitrate in the Krebs cycle. The function of ACO gene family members has been extensively studied in model plants, for instance Arabidopsis. However, their role in plant developmental processes and various stress conditions largely remained unknown in other plant species. Thus, we identified 15 ACO genes in wheat to elucidate their function in plant developmental processes and different stress environments. The phylogenetic tree revealed that TaACO genes were classified into six groups. Further, gene structure analysis of TaACOs has shown a distinctive evolutionary path. Synteny analysis showed the 84 orthologous gene pairs in Brachypodium distachyon, Aegilops tauschii, Triticum dicoccoides, Oryza sativa, and Arabidopsis thaliana. Furthermore, Ka/Ks ratio revealed that most TaACO genes experienced strong purifying selection during evolution. Numerous cis-acting regulatory elements were detected in the TaACO promoters, which play a crucial role in plant development processes, phytohormone signaling, and are related to defense and stress. To understand the function of TaACO genes, the expression profiling of TaACO genes were investigated in different tissues, developmental stages, and stress conditions. The transcript per million values of TaACOs genes were retrieved from the Wheat Expression Browser Database. We noticed the differential expression of the TaACO genes in different tissues and various stress conditions. Moreover, gene ontology analysis has shown enrichment in the tricarboxylic acid metabolic process (GO:0072350), citrate metabolic process (GO:0006101), isocitrate metabolic process GO:0006102, carbohydrate metabolic (GO:0005975), and glyoxylate metabolic process (GO:0046487). Therefore, this study provided valuable insight into the ACO gene family in wheat and contributed to the further functional characterization of TaACO during different plant development processes and various stress conditions.

Exoskeleton design utilizing foot-strike energy for enhancing the climbing ability of the wearer.

In this paper, a passive exoskeleton is developed to strengthen the motion ability of the knee joint bearing four times the body weight during climbing mountains or stairs. With the novel design, an inverted cam mechanism is designed to transform foot-strike energy to joint positive work of the knee joint, a type-selection mechanism for spring steel bars, and further their application model based on the linear elastic theory of metal materials are established, and to attach the exoskeleton assistance torque to the energy consumption characteristics of the knee joint, the moment-arm variation and the cam profile of the inverted cam mechanism are investigated. In addition, this paper proposes the potential link between the utilization of foot-strike energy and discrete power assistance for the knee joint, which creates simplifying conditions for exoskeleton designs with clutch mechanisms. Finally, to verify the effectiveness of the exoskeleton design, two exoskeleton prototypes were used for respiratory metabolism tests, in which 75% of the test results obtained an average power-assistant efficiency of 14.15%.

Integrative physiological, transcriptome, and metabolome analysis uncovers the drought responses of two Zanthoxylum bungeanum cultivars

Zanthoxylum bungeanum (ZB) is a medicinal plant that is widely cultivated in arid and semi-arid areas. The drought tolerance mechanism of ZB has not yet been clearly elucidated. Here, the physiological indicators, transcriptome, and metabolome of two ZB cultivars with contrasting drought tolerance (FJ, Z. bungeanum cv. ‘Fengjiao’; HJ, Z. bungeanum cv. ‘Hanjiao’) were analyzed under drought stress. The results showed that HJ was more tolerant to drought stress, with stronger antioxidant enzyme activities, higher contents of soluble sugar, soluble protein and proline as well as lower content of malondialdehyde and H2O2. Transcriptome analysis revealed that there were more differentially expressed genes in FJ than in HJ throughout the drought treatment. Metabolome analysis identified 911 metabolites, which were divided into 10 classes. The up-regulated metabolites in HJ were mainly amino acids and their derivatives and flavonoids; those in FJ were mainly amino acids and their derivatives and alkaloids. Candidate structural genes related to drought tolerance and key transcription factor genes involved in drought-response pathways were sheltered by weighted gene co-expression network analysis (WGCNA). Conjoint analysis of the transcriptome and metabolome emphasized the importance of respiration metabolism in enhancing drought tolerance. In general, HJ improves drought tolerance by enhancing antioxidant enzyme activities; increasing the intensity of the pentose phosphate pathway; promoting the accumulation of osmotic substances; stimulating the synthesis of abscisic acid, brassinosteroid, and heat shock proteins; and accelerating signal transduction. The results improve our understanding of the molecular mechanism of drought tolerance in ZB and provide new insights for molecular breeding of ZB as well as other crops.

Cellular and computational models reveal environmental and metabolic interactions in MMUT-type methylmalonic aciduria.

Methylmalonyl-coenzyme A (CoA) mutase (MMUT)-type methylmalonic aciduria is a rare inherited metabolic disease caused by the loss of function of the MMUT enzyme. Patients develop symptoms resembling those of primary mitochondrial disorders, but the underlying causes of mitochondrial dysfunction remain unclear. Here, we examined environmental and genetic interactions in MMUT deficiency using a combination of computational modeling and cellular models to decipher pathways interacting with MMUT. Immortalized fibroblast (hTERT BJ5ta) MMUT-KO (MUTKO) clones displayed a mild mitochondrial impairment in standard glucose-based medium, but they did not to show increased reliance on respiratory metabolism nor reduced growth or viability. Consistently, our modeling predicted MUTKO specific growth phenotypes only for lower extracellular glutamine concentrations. Indeed, two of three MMUT-deficient BJ5ta cell lines showed a reduced viability in glutamine-free medium. Further, growth on 183 different carbon and nitrogen substrates identified increased NADH (nicotinamide adenine dinucleotide) metabolism of BJ5ta and HEK293 MUTKO cells compared with controls on purine- and glutamine-based substrates. With this knowledge, our modeling predicted 13 reactions interacting with MMUT that potentiate an effect on growth, primarily those of secondary oxidation of propionyl-CoA, oxidative phosphorylation and oxygen diffusion. Of these, we validated 3-hydroxyisobutytyl-CoA hydrolase (HIBCH) in the secondary propionyl-CoA oxidation pathway. Altogether, these results suggest compensation for the loss of MMUT function by increasing anaplerosis through glutamine or by diverting flux away from MMUT through the secondary propionyl-CoA oxidation pathway, which may have therapeutic relevance.

Spectroscopic Study of Time-Varying Optical Redox Ratio in NADH/FAD Solution.

Autofluorescence imaging has been widely applied as advanced noninvasive diagnostics for in vivo and ex vivo tissues. The optical redox ratio (ORR), which is defined as the fluorescence intensity ratio between reduced nicotine adenine dinucleotide (NADH) and oxidized flavin adenine dinucleotide (FAD), has been used as a diagnostic parameter strongly, because NADH and FAD play an important role in energetic and respiratory metabolism as coenzymes. The ORR method has provided successful assessment in cancer diagnosis including breast, cervical, and oral cancer; few studies have been reported about optical and chemical interference between two molecules resulting in a change in ORR values. In this study, we investigated the variations in ORR values of NADH/FAD mixtures dissolved in tris(hydroxymethyl)aminomethane, phosphate buffer, and deionized water environments. In vitro solutions were prepared in various concentration ratios and the experimental and theoretical ORR values were obtained from fluorescence and absorption spectra in time series. Based on the spectroscopic analysis, we concluded that the inner filter effect causes an instant decrease in FAD fluorescence just after dissolution and that the oxidation-reduction coupled with oxygenation reaction results in time-varying decreases in NADH fluorescence and FAD emission.

Characterization of controlled-release Eucalyptus citriodora oil/Zinc ions nanoparticles with enhanced antibacterial properties against E. coli O157:H7 in fruit juice

Eucalyptus citriodora oil (ECO) has excellent antibacterial properties, but its application is limited due to its volatility and lack of antimicrobial targeting properties. Zinc ions are metal ions on which the active center of metalloproteinases depend and have antibacterial functions. This study aimed to prepare nanoparticles against Escherichia coli O157:H7 (E. coli O157:H7) by encapsulating ECO in zein with nano-precipitation method, and chelating zinc metal ions with electrostatic interaction to improve the stability, controlled-release ability and antibacterial ability of nanoparticles. Herein, the antibacterial mechanism of ECO against E. coli O157:H7 was investigated from the molecular level. The results of molecular docking showed that ECO inhibited the activity of G6PDH in respiratory metabolism pathway (hexose monophophate pathway), and also inhibited the DNA polymerase. Furthermore, we demonstrated that the controlled-release nanoparticles (ECO/Zn2+-loaded NPT) possessed suitable particle size (275.43 nm), poly dispersity index (PDI, 0.254), zeta potential (-31.12 mV) and chelation rate (42.3 %). The results of Fourier Transform Infrared spectrometer (FT-IR), and Raman spectrum confirmed that ECO was successfully encapsulated in the nanoparticles. Meanwhile, the results of antibacterial experiments showed that ECO/Zn2+-loaded NPT possessed better antibacterial activity than ECO/zein nanoparticles. Finally, the test of application in fruit juice indicated that ECO/Zn2+-loaded NPT had no significant effect on physico-chemical properties and exhibited potential application in juice preservation.

Contrasting seasonal dynamics of dormancy, respiratory metabolism and cell cycle state in grapevine buds of a subtropical and Mediterranean climate

AbstractGrapevine (Vitis vinifera L.) is the most widely cultivated fruit crop worldwide, contributing substantially to rural economies. The production cycle and productivity depend on seasonal cues and can range from a strongly deciduous habit in cool‐temperate climates to evergreen in subtropical and tropical climates. The influence of the different seasonal conditions on the dynamics of the perennating bud, including the degree of growth and metabolic quiescence, cell cycle status and internal tissue oxygen status between different climatic zones is largely unknown. This knowledge is important for adapting to changing climate conditions and for crop expansion to wider regions. This study investigated the growth and metabolic physiology of the perennating bud of commercially grown cv. Flame Seedless table grapes from Mediterranean and subtropical climate in Western Australia, from summer until late winter. Climate data were obtained, showing differences in minimum (night) temperature between the two climates, reflected by differences in calculated chilling units. Bud dormancy increased during autumn of both climates;however, the onset and depth of dormancy of buds from the subtropical region were attenuated relative to the Mediterranean condition. Stark contrasts were also observed in metabolism. The respiration of subtropical‐grown buds increased over fivefold during late autumn and winter, while that of Mediterranean‐grown buds increased less than twofold. This was also reflected in less desiccation of the subtropical‐grown buds, and an apparently greater degree of hypoxia within the bud during late winter, prior to bud burst. Collectively, these data show pronounced differences in growth and metabolic physiology of commercially grown table grapes, which provide a foundation for investigating the influence of differing climate and seasonality on the growth and productivity of table grapes and how these may be managed through breeding and agronomy.

MaMYB13 is involved in response to chilling stress via activating expression of VLCFAs and phenylpropanoids biosynthesis-related genes in postharvest banana fruit

Fruit chilling injury is the result of physiological dysfunction due to membrane lipid phase change, oxidative damage of biomacromolecules and respiratory metabolism abnormality. However, the involvement of transcription factors in response to fruits chilling tolerance remains largely unclear. Here, MaMYB13 was identified to participate in banana fruit response to chilling stress. MaMYB13 has transcriptional activation activity. When exposed to low temperature, expression of MaMYB13 was enormously induced. Moreover, MaMYB13 promoter was activated by chilling stress. MaMYB13 bound to the promoters of several important very-long-chain fatty acids (VLCFAs) and phenylpropanoids biosynthesis-related genes, including MaKCS11, Ma4CL6 and MaAAE1, and activated their transcription. Furthermore, MaKIN10 X1/3 interacted with MaMYB13 and enhanced MaMYB13-mediated transcriptional activation possibly via phosphorylation. Altogether, our results unravel the mechanism of MaMYB13-MaKIN10 X1/3 interaction regulating banana fruit chilling tolerance through activating the expression of MaKCS11, Ma4CL6 and MaAAE1, providing new insights into the regulatory network of MYB transcription factor.

Light spectrum impacts on development respiratory metabolism and antioxidant capacity of larval swimming crab Portunus trituberculatus

The effects of the spectrum on the development, respiratory metabolism, and antioxidant capacity of the larval swimming crab Portunus trituberculatus were studied. Seven light spectra, i.e., purple (400 nm), blue (425 nm), cyan (510 nm), green (525 nm), yellow (598 nm), red (638 nm), and white (full spectrum), were estimated. The larvae had the optimum survival rate and development under cyan light. On the contrary, larvae in red and yellow lights had poor growth performance. The oxygen consumption rate (OCR) dropped while the ammonia excretion rate (AER) rose as the larvae developed. Early larvae’s oxygen-nitrogen ratio (O: N) fell when exposed to red light, suggesting more protein was utilized in the respiratory process. Regarding the antioxidant system, crab had the lowest malondialdehyde (MDA) under green, cyan and yellow light, and the highest total antioxidant capacity (T-AOC) in cyan light. Taken together, the current results suggest that cyan was the optimum spectrum for the development of P. trituberculatus larvae.

Antibacterial and antioxidative biogenic films for room-temperature strawberry preservation

The shelf life of strawberries is prone to be shortened by microbial infection and respiratory metabolism, significantly restricting its availability. Advanced preservation films hold considerable promise to overcome this problem. Herein, a biogenic ternary tannic acid/chitosan-citric acid (TA/CS-CA) preservation film was developed and demonstrated remarkable room-temperature strawberry preservation. CS dissolved in CA solution was able to form a fast in-situ film with TA owing to their strong hydrogen bonding. The excellent antibacterial activity (about 90 % for both E. coli and S. aureus) combined with superior oxidation resistance (the DPPH∙ scavenging activity of 90.0 %) were inherited from their ingredients. Consequently, the edible rate of TA/CS-CA film-coated strawberries upon storing at 19–25 °C for 7 days and the freshness lifetime increased to 74.1 % and 112.0 h, which were about twice those of uncoated strawberries, respectively. Moreover, this film exhibited favourable washability and inherent biocompatibility, making it promising as a high-performance preservation material.

Proanthocyanidin delays litchi peel browning by inhibiting ethylene biosynthesis, respiratory metabolism, and phenol oxidase activities

Proanthocyanidin (PA) promotes antioxidant capacity and enhances resistance against oxidative stress-induced senescence in fruits after harvest. However, the effects of PA on the postharvest physiology of litchi fruit remain unclear. This study aimed to determine the effect of PA on ethylene and respiration physiology, and on browning enzymes of ‘feizixiao’ litchi stored at 25 °C for 8 d. Proanthocyanidin treatment delayed peel browning and color change, maintained higher peel lightness, and reduced ethylene production and respiration rates in litchi fruit. Subsequently, the key genes and/or enzymes involved in the ethylene biosynthesis pathway and respiration metabolism were determined. The PA-treated fruit exhibited lower levels of 1-aminocyclopropanecarboxylic acid (ACC) content, ACC synthase (ACS) and ACC oxidase (ACO) activity, and an inhibition of LcACS7/9 and LcACO1/2 genes on the peel and pulp compared to that of the control. In addition, the application of PA reduced respiration rate by downregulating the expression of LcAtpB, LcAOX1, LcUCP1, LcAAC1, and LcSnRK2. Furthermore, the phenol oxidase including peroxidase (POD), polyphenol oxidase (PPO), and laccase (LAC), were inhibited during litchi peel browning and senescence. Therefore, the process of PA-delayed browning of litchi may occur by delaying ethylene production and respiratory rate and inhibiting phenol oxidase activities in litchi fruit.

Hypoxia-Activatable Nanovesicles as In Situ Bombers for Combined Hydrogen-Sulfide-Mediated Respiration Inhibition and Photothermal Therapy.

Photothermal therapy (PTT) has emerged as a promising alternative or supplement to cancer treatments. While PTT induces the ablation of solid tumors, its efficiency is hampered by self-recovery within impaired cancer cells through glycolysis and respiration metabolism. Based on this, the introduction of hydrogen sulfide (H2S)-mediated respiration inhibition is a good choice to make up for the PTT limitation. Herein, nanovesicles (NP1) are integrated by a hypoxia-responsive conjugated polymer (P1), polymetric H2S donor (P2), and near-infrared (NIR) light-harvesting aza-BODIPY dye (B1) for the delivery of H2S and synergistic H2S gas therapy/PTT. The scaffold of NP1 undergoes disassembly in the hypoxic environments, thus triggering the hydrolysis of P2 to continuously long-term release H2S. Dependent on the superior photothermal ability of B1, NP1 elicits high photothermal conversion efficiency (η = 19.9%) under NIR light irradiation for PTT. Moreover, NP1 serves as in situ H2S bombers in the hypoxic tumor environment and suppresses the mitochondrial respiration through inhibiting expression of cytochrome c oxidase (COX IV) and cutting off the adenosine triphosphate (ATP) generation. Both in vitro and in vivo results demonstrate good antitumor efficacy of H2S gas therapy/PTT, which will be recommended as an advanced strategy for cancer therapeutics.

Hybridization drives mitochondrial DNA degeneration and metabolic shift in a species with biparental mitochondrial inheritance.

Mitochondrial DNA (mtDNA) is a cytoplasmic genome that is essential for respiratory metabolism. Although uniparental mtDNA inheritance is most common in animals and plants, distinct mtDNA haplotypes can coexist in a state of heteroplasmy, either because of paternal leakage or de novo mutations. mtDNA integrity and the resolution of heteroplasmy have important implications, notably for mitochondrial genetic disorders, speciation, and genome evolution in hybrids. However, the impact of genetic variation on the transition to homoplasmy from initially heteroplasmic backgrounds remains largely unknown. Here, we use Saccharomyces yeasts, fungi with constitutive biparental mtDNA inheritance, to investigate the resolution of mtDNA heteroplasmy in a variety of hybrid genotypes. We previously designed 11 crosses along a gradient of parental evolutionary divergence using undomesticated isolates of Saccharomyces paradoxus and Saccharomyces cerevisiae Each cross was independently replicated 48 to 96 times, and the resulting 864 hybrids were evolved under relaxed selection for mitochondrial function. Genome sequencing of 446 MA lines revealed extensive mtDNA recombination, but the recombination rate was not predicted by parental divergence level. We found a strong positive relationship between parental divergence and the rate of large-scale mtDNA deletions, which led to the loss of respiratory metabolism. We also uncovered associations between mtDNA recombination, mtDNA deletion, and genome instability that were genotype specific. Our results show that hybridization in yeast induces mtDNA degeneration through large-scale deletion and loss of function, with deep consequences for mtDNA evolution, metabolism, and the emergence of reproductive isolation.

Delayed root water supply result in spring dieback of Cabernet Sauvignon in northern China

Cabernet Sauvignon (Vitis vinifera) is one of the main wine-making varieties in the world. Its budding time is late, and cane dieback often occurs in northern China. In order to analyze the causes of shoot drying death of Cabernet Sauvignon in spring, the water supply capacity of the roots of Cabernet Sauvignon and Early-ripening Kyoho and the dynamic changes in the respiration metabolism of roots and buds during the ecodormancy were studied. Additionally, the effects of rootstock SA15 grafting on the sap flow and moisture content changes of Cabernet Sauvignon canes were investigated and the expression of root respiration related genes at different temperatures during the ecodormancy after rootstock SA15 grafting was analyzed. The results showed that compared with Early-ripening Kyoho, the xylem sap flow intensity of Cabernet Sauvignon was low and unstable during the ecodormancy, the roots water reached the peak later, and changes in the respiratory pathways and the accumulation of soluble sugar occurred slowly. The peak of the activity of the respiratory pathways in the Cabernet Sauvignon buds occurred significantly earlier than that of the roots. Compared with self-rooted vines, the peak in the sap flow of Cabernet Sauvignon canes grafted on rootstock SA15 occurred 24 days earlier, and the recovery times of the total water content and free water content occurred earlier. It also increased the roots respiration intensity and the expression of key enzymes of roost respiration under low temperature. In summary, Cabernet Sauvignon insufficient water supply capacity, resulting in difficulty replenishing the water lost from the canes in time and ultimately leading to spring dieback of Cabernet Sauvignon canes. The moisture recovery time of Cabernet Sauvignon canes can be increased by grafting them on rootstock SA15 to prevent the occurrence of spring dieback.

Non-canonical phosphoglycerate dehydrogenase activity promotes liver cancer growth via mitochondrial translation and respiratory metabolism.

Phosphoglycerate dehydrogenase (PHGDH) is a key serine biosynthesis enzyme whose aberrant expression promotes various types of tumors. Recently, PHGDH has been found to have some non-canonical functions beyond serine biosynthesis, but its specific mechanisms in tumorigenesis remain unclear. Here, we show that PHGDH localizes to the inner mitochondrial membrane and promotes the translation of mitochondrial DNA (mtDNA)-encoded proteins in liver cancer cells. Mechanistically, we demonstrate that mitochondrial PHGDH directly interacts with adenine nucleotide translocase 2 (ANT2) and then recruits mitochondrial elongation factor G2 (mtEFG2) to promote mitochondrial ribosome recycling efficiency, thereby promoting mtDNA-encoded protein expression and subsequent mitochondrial respiration. Moreover, we show that treatment with a mitochondrial translation inhibitor or depletion of mtEFG2 diminishes PHGDH-mediated tumor growth. Collectively, our findings uncover a previously unappreciated function of PHGDH in tumorigenesis acting via promotion of mitochondrial translation and bioenergetics.

Integration of transcriptome, miRNA and degradome sequencing reveals the early browning response in fresh-cut apple

Surface browning negatively impacts the shelf-life of fresh-cut apple. Herein, we found that the browning of fresh-cut apple aggravated rapidly after 24 h post-cutting, then the transcriptomic and miRNA expression profiles of fresh-cut apple immediately after cutting (T0) and 24 h post-cutting (T24) were analyzed to explore the molecular mechanism of early browning response. A total of 3156 differentially expressed mRNAs (DEGs) and 23 differentially expressed miRNAs (DEmiRNAs) were identified in T24 vs T0. Most DEGs related to respiratory, energy, antioxidant, lipid and secondary metabolism were activated in the early stage of browning. There were 63 target genes of 10 DEmiRNAs validated by degradome sequencing and among them, mdm-miR156aa_L + 1_1 targets 12-oxophytodienoate reductase, ptc-miR6478_R-1 targets patatin-like protein, mdm-miR156aa_L + 1_1 and mdm-miR156aa_L + 1_2 co-target SPLs might participate in the early browning response through regulating antioxidant, lipid and secondary metabolism. Our results will be beneficial for the technological innovation of browning amelioration for fresh-cut apple.