Capacity For Protein Synthesis Research Articles

Programmed cell death regulator BAP2 is required for IRE1-mediated unfolded protein response in Arabidopsis

Environmental and physiological situations can challenge the balance between protein synthesis and folding capacity of the endoplasmic reticulum (ER) and cause ER stress, a potentially lethal condition. The unfolded protein response (UPR) restores ER homeostasis or actuates programmed cell death (PCD) when ER stress is unresolved. The cell fate determination mechanisms of the UPR are not well understood, especially in plants. Here, we integrate genetics and ER stress profiling with natural variation and quantitative trait locus analysis of 350 natural accessions of the model species Arabidopsis thaliana. Our analyses implicate a single nucleotide polymorphism to the loss of function of the general PCD regulator BON-ASSOCIATED PROTEIN2 (BAP2) in UPR outcomes. We establish that ER stress-induced BAP2 expression is antagonistically regulated by the UPR master regulator, inositol-requiring enzyme 1 (IRE1), and that BAP2 controls adaptive UPR amplitude in ER stress and ignites pro-death mechanisms in conditions of UPR insufficiency.

Ferroptosis induces nucleolar stress as revealed by live-cell imaging using thioflavin T

Nucleolar stress induced by stressors like hypoxia, UV irradiation, and heat shock downregulates ribosomal RNA transcription, thereby impairing protein synthesis capacity and potentially contributing to cell senescence and various human diseases such as neurodegenerative disorders and cancer. Live-cell imaging of the nucleolus may be a feasible strategy for investigating nucleolar stress, but currently available nucleolar stains are limited for this application. In this study using mouse hippocampal HT22 cells, we demonstrate that thioflavin T (ThT), a benzothiazole dye that binds RNA with high affinity, is useful for nucleolar imaging in cells where RNAs predominate over protein aggregates. Nucleoli were stained with high intensity simply by adding ThT to the cell culture medium, making it suitable for use even in damaged cells. Further, ThT staining overlapped with specific nucleolar stains in both live and fixed cells, but did not overlap with markers for mitochondria, lysosomes, endoplasmic reticulum, and double-stranded DNA. Ferroptosis, an iron-dependent nonapoptotic cell death pathway characterized by lipid peroxide accumulation, reduced the number of ThT-positive puncta while endoplasmic reticulum stress did not. These findings suggest that ferroptosis is associated with oxidative damage to nucleolar RNA molecules and ensuing loss of nucleolar function.

239 Variation in muscle protein synthesis in growing gilts is partially associated with insulin resistance and sensitivity

Abstract Pigs with similar body weight (BW), same genetic background and sex vary in protein deposition (PD) overgrowth. We aimed to study metabolic factors influencing PD in 65 kg BW gilts. Gilts were fed ad libitum a diet balanced to maximize PD. Dual X-rays were conducted to estimate body protein mass on d 1 and 21, allowing calculation of PD by difference. On d 23, the gilts were categorized into Low (157 g/d) and High (219 ± 9.97 g/d) PD groups. In each group, eight pigs underwent jugular vein cannulation. After a 48-h recovery period, where they were fed at 90% of the measured feed intake, they were fasted for 8 h. All pigs were then given a 300 g meal at time 0, and blood samples were collected at 10, 15, 20, 30, 40, 50, 60, 75, 90, 120, 150, 178, and 178 min, to study insulin and glucose responses. At 180 min post-meal, a solution of L-13C valine was administered i.v. (18 ape – flooding dose), and liver, duodenum, and longissimus dorsi muscle samples were collected within 5 minutes of slaughter. The fractional synthesis rate (FSR, %/d), absolute synthesis rate (ASR, g/d), ribosomal capacity for protein synthesis (Cs), and the efficiency of protein synthesis (KRNA) based on total RNA concentration in skeletal muscle were calculated. The insulin resistance index (HOMA-B) and insulin sensitivity index (QUICKI) were also determined. The difference between Low and High PD gilts was compared using a F-test. The longissimus dorsi muscle exhibited a 31% greater (P = 0.01) FSR in High compared with Low PD group. No significant differences were observed in the FSR of the jejunum and liver. High PD gilts showed a 55% greater ASR in whole-body muscles (P = 0.003) and 42% greater ASR in the liver (P = 0.04) compared with Low PD gilts, with no difference for the ASR in the jejunum. The KRNA in the longissimus dorsi was 48% greater in High PD gilts (P = 0.01), with no differences in KRNA for the jejunum or liver. Cs did not differ between Low and High PD gilts. The QUICKI index tended to be greater in High PD gilts (P = 0.10). Spearman’s correlation revealed that longissimus dorsi FSR was negatively correlated with the HOMA-B index (r = -0.53; P = 0.04). Increases in the HOMA-B index tended to be associated with greater KRNA (r = -0.49; P = 0.06). These correlations highlight the complex interplay of metabolic and hormonal factors involved in the observed differences in protein synthesis and efficiency in growing gilts. Insulin resistance and sensitivity may play a role in influencing skeletal muscle PD variations.

Dynamic molecular signatures of acute myocardial infarction based on transcriptomics and metabolomics

Acute myocardial infarction (AMI) commonly precedes ventricular remodeling, heart failure. Few dynamic molecular signatures have gained widespread acceptance in mainstream clinical testing despite the discovery of many potential candidates. These unmet needs with respect to biomarker and drug discovery of AMI necessitate a prioritization. We enrolled patients with AMI aged between 30 and 70. RNA-seq analysis was performed on the peripheral blood mononuclear cells collected from the patients at three time points: 1 day, 7 days, and 3 months after AMI. PLC/LC–MS analysis was conducted on the peripheral blood plasma collected from these patients at the same three time points. Differential genes and metabolites between groups were screened by bio-informatics methods to understand the dynamic changes of AMI in different periods. We obtained 15 transcriptional and 95 metabolite expression profiles at three time points after AMI through high-throughput sequencing. AMI-1d: enrichment analysis revealed the biological features of 1 day after AMI primarily included acute inflammatory response, elevated glycerophospholipid metabolism, and decreased protein synthesis capacity. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) might stand promising biomarkers to differentiate post-AMI stage. Anti-inflammatory therapy during the acute phase is an important direction for preventing related pathology. AMI-7d: the biological features of this stage primarily involved the initiation of cardiac fibrosis response and activation of platelet adhesion pathways. Accompanied by upregulated TGF-beta signaling pathway and ECM receptor interaction, GP5 help assess platelet activation, a potential therapeutic target to improve haemostasis. AMI-3m: the biological features of 3 months after AMI primarily showed a vascular regeneration response with VEGF signaling pathway, NOS3 and SHC2 widely activated, which holds promise for providing new therapeutic approaches for AMI. Our analysis highlights transcriptional and metabolomics signatures at different time points after MI, which deepens our understanding of the dynamic biological responses and associated molecular mechanisms that occur during cardiac repair.

Myotube growth is associated with cancer-like metabolic reprogramming and is limited by phosphoglycerate dehydrogenase and pyruvate kinase M2

Skeletal myofiber size and oxidative metabolism are inversely related. Glycolytic fast type myofibers are larger than high high oxidative, slow type myofibers. Paradoxically, despite their lower capacity for protein synthesis (lower myonucluar density and RNA content), glycolytic, low oxidative are more responsive to an anabolic stimulus. We hypothesized that glycolytic myofibers may make use of a Warburg-like metabolic reprogramming in response to an anabolic stimulus. The Warburg effect links growth and glycolysis in tumor cells to generate glycolytic intermediates for synthesis of nucleotides and amino. The aim of this study was to test whether a similar ‘glycolysis-for-anabolism’ metabolic reprogramming also occurs in post-mitotic, hypertrophying myofibers. For this purpose, we first induced C2C12 myotube hypertrophy with IGF-1. We then added 14C glucose to the differentiation medium and measured radioactivity in isolated protein and RNA to establish whether 14C had entered anabolism. We found that especially protein became radioactive, suggesting a glucose → glycolytic intermediates → non-essential amino acid(s) → protein series of reactions, the rate of which was increased by IGF-1. Next, to investigate the importance of glycolytic flux and non-essential amino acid synthesis for myotube hypertrophy, we exposed C2C12 and primary mouse myotubes to the glycolysis inhibitor 2-Deoxy-D-glucose (2DG). We found that inhibiting glycolysis lowered C2C12 and primary myotube size. Similarly, siRNA silencing of PHGDH and PKM2, key enzymes of the Warburg-like metabolic reprogramming, reduced C2C12 and primary myotube growth; whereas retroviral PHGDH overexpression increased C2C12 myotube size. Together these results suggest that glycolysis is important for hypertrophying myotubes, which reprogramme their metabolism to facilitate anabolism, similar to cancer cells. Brendan M. Gabriel was supported by fellowships from the Novo Nordisk Foundation (NNF19OC0055072) & the Wenner-Gren Foundation, an Albert Renold Travel Fellowship from the European Foundation for the Study of Diabetes, and an Eric Reid Fund for Methodology from the Biochemical Society. Abdalla D. Mohamed was funded initially by Sarcoma UK (grant number SUK09.2015), then supported by funding from Postdoctoral Fellowship Program (Helmholtz Zentrum München, Germany), and currently by Cancer Research UK. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Fluorescent reporters give new insights into antibiotics-induced nonsense and frameshift mistranslation

We developed a reporter system based on simultaneous expression of two fluorescent proteins: GFP as a reporter of the capacity of protein synthesis and mutated mScarlet-I as a reporter of translational errors. Because of the unique stop codons or frameshift mutations introduced into the mScarlet-I gene, red fluorescence was produced only after a mistranslation event. These reporters allowed us to estimate mistranslation at a single cell level using either flow cytometry or fluorescence microscopy. We found that laboratory strains of Escherichia coli are more prone to mistranslation compared to the clinical isolates. As relevant for uropathogenic E. coli, growth in human urine elevated translational frameshifting compared to standard laboratory media, whereas different standard media had a small effect on translational fidelity. Antibiotic-induced mistranslation was studied by using amikacin (aminoglycoside family) and azithromycin (macrolide family). Bactericidal amikacin induced preferably stop-codon readthrough at a moderate level. Bacteriostatic azithromycin on the other hand induced both frameshifting and stop-codon readthrough at much higher level. Single cell analysis revealed that fluorescent reporter-protein signal can be lost due to leakage from a fraction of bacteria in the presence of antibiotics, demonstrating the complexity of the antimicrobial activity.

Paradoxical imbalance between activated lymphocyte protein synthesis capacity and rapid division rate.

Rapid lymphocyte cell division places enormous demands on the protein synthesis machinery. Flow cytometric measurement of puromycylated ribosome-associated nascent chains after treating cells or mice with translation initiation inhibitors reveals that ribosomes in resting lymphocytes in vitro and in vivo elongate at typical rates for mammalian cells. Intriguingly, elongation rates can be increased up to 30% by activation in vivo or fever temperature in vitro. Resting and activated lymphocytes possess abundant monosome populations, most of which actively translate in vivo, while in vitro, nearly all can be stalled prior to activation. Quantitating lymphocyte protein mass and ribosome count reveals a paradoxically high ratio of cellular protein to ribosomes insufficient to support their rapid in vivo division, suggesting that the activated lymphocyte proteome in vivo may be generated in an unusual manner. Our findings demonstrate the importance of a global understanding of protein synthesis in lymphocytes and other rapidly dividing immune cells.

Paradoxical imbalance between activated lymphocyte protein synthesis capacity and rapid division rate

Rapid lymphocyte cell division places enormous demands on the protein synthesis machinery. Flow cytometric measurement of puromycylated ribosome-associated nascent chains after treating cells or mice with translation initiation inhibitors reveals that ribosomes in resting lymphocytes in vitro and in vivo elongate at typical rates for mammalian cells. Intriguingly, elongation rates can be increased up to 30% by activation in vivo or fever temperature in vitro. Resting and activated lymphocytes possess abundant monosome populations, most of which actively translate in vivo, while in vitro, nearly all can be stalled prior to activation. Quantitating lymphocyte protein mass and ribosome count reveals a paradoxically high ratio of cellular protein to ribosomes insufficient to support their rapid in vivo division, suggesting that the activated lymphocyte proteome in vivo may be generated in an unusual manner. Our findings demonstrate the importance of a global understanding of protein synthesis in lymphocytes and other rapidly dividing immune cells.

Tubule dysfunction and injury and future risk of sepsis-associated acute kidney injury.

Novel biomarkers can quantify both kidney tubule function, including proximal tubule reabsorptive (urine α-1 microglobulin (uα1m)) and tubule protein synthesis capacities (urine uromodulin (uUMOD)), and tubular injury (urine neutrophil gelatinase-associated lipocalin (uNGAL)). In a blood pressure trial, we reported that lower reabsorptive and synthetic protein capacity at times of health predicted future risk of acute kidney injury (AKI), but most AKI was related to hemodynamic causes in this trial. Associations between tubular function and injury and future AKI related to other causes is unknown. We performed a case-control study in REGARDS, a population-based cohort study, among participants who provided urine at the baseline visit. We matched each septic AKI case by age, sex, race, and time from baseline to hospital admission 1:1 to a participant with sepsis who did not develop AKI (controls). Using conditional logistic regression, we evaluated the associations of uα1m, uUMOD, urine ammonium, and uNGAL with septic AKI. Mean age was 69 ± 8 years, 44% were female, and 39% were Black participants. Median baseline eGFR among cases and controls was 73 (55, 90) and 82 (65, 92) mL/min/1.73m2, and median albuminuria was 19 (8, 87) vs. 9 (5, 22) mg/g, respectively. No independent associations were observed between the tubule function or injury markers and subsequent risk of septic AKI once models were adjusted for baseline albuminuria, estimated glomerular filtration rate, and other risk factors. Among community participants, tubule function and injury markers at times of health were not independently associated with future risk of septic AKI.

Dietary supplementation of Aurantiochytrium sp. significantly improved growth, feed utilization, skin lightness, muscle protein synthesis capacity, and whole-body protein in juvenile African sharptooth catfish (Clarias gariepinus)

Cultivated Aurantiochytrium sp. FIKU018 contained 64.0% crude lipid, 22.6% crude protein, and 4.47% crude ash, on a dry matter basis. This ingredient has been supplemented in artificial diets across a number of aquatic animal species. However, no studies have evaluated this dietary supplement for African sharptooth catfish (Clarias gariepinus) aquaculture. In this study, isonitrogenous, isolipidic, and isoenergetic diets were formulated containing different grade levels of dried Aurantiochytrium sp. (0, 2, 4, 6, 8, and 10%). These diets were given to triplicate groups of juvenile African sharptooth catfish (1.68–1.70 g body weight) for six weeks. At the end of the feeding trial, fish in all treatments had similar survival rates, ranging from 88.9% to 97.2% (P > 0.05). The growth performance (weight gain = 68.5 g) and feed utilization (feed conversion ratio = 1.47 g feed g gain−1, protein efficiency ratio = 1.94 g gain g protein−1) indicated a suitable level of 6% dried Aurantiochytrium sp. in diet. Based on broken-line analysis indicated an optimal supplementation level of 6.41% would produce the highest weight gain. This preferred treatment significantly improved skin lightness, muscle protein synthesis capacity, and whole-body crude protein (P < 0.05) without causing effects on fillet color parameters, digestive enzyme activities, and myosin and actin in white muscle (P > 0.05). Our observations suggest that 6.41% is the optimal dietary supplementation level of Aurantiochytrium sp. for juvenile African catfish. The supplemented diet that produced the best results can be used in the cultivation of African sharptooth catfish, and could support the use of dried Aurantiochytrium meal as an alternative feed supplement for other aquatic animals.

‘Mother(Nature) knows best’ – hijacking nature-designed transcriptional programs for enhancing stress resistance and protein production in Yarrowia lipolytica; presentation of YaliFunTome database

BackgroundIn the era of rationally designed synthetic biology, heterologous metabolites production, and other counter-nature engineering of cellular metabolism, we took a step back and recalled that ‘Mother(-Nature) knows best’. While still aiming at synthetic, non-natural outcomes of generating an ‘over-production phenotype’ we dug into the pre-designed transcriptional programs evolved in our host organism—Yarrowia lipolytica, hoping that some of these fine-tuned orchestrated programs could be hijacked and used. Having an interest in the practical outcomes of the research, we targeted industrially-relevant functionalities—stress resistance and enhanced synthesis of proteins, and gauged them over extensive experimental design’s completion.ResultsTechnically, the problem was addressed by screening a broad library of over 120 Y. lipolytica strains under 72 combinations of variables through a carefully pre-optimized high-throughput cultivation protocol, which enabled actual phenotype development. The abundance of the transcription program elicitors—transcription factors (TFs), was secured by their overexpression, while challenging the strains with the multitude of conditions was inflicted to impact their activation stratus. The data were subjected to mathematical modeling to increase their informativeness.The amount of the gathered data prompted us to present them in the form of a searchable catalog – the YaliFunTome database (https://sparrow.up.poznan.pl/tsdatabase/)—to facilitate the withdrawal of biological sense from numerical data. We succeeded in the identification of TFs that act as omni-boosters of protein synthesis, enhance resistance to limited oxygen availability, and improve protein synthesis capacity under inorganic nitrogen provision.ConclusionsAll potential users are invited to browse YaliFunTome in the search for homologous TFs and the TF-driven phenotypes of interest.

Improved capacity for the repair of photosystem II via reinforcement of the translational and antioxidation systems in Synechocystis sp. PCC 6803.

In the cyanobacterium Synechocystis sp. PCC 6803, translation factor EF-Tu is inactivated by reactive oxygen species (ROS) via oxidation of Cys82 and the oxidation of EF-Tu enhances the inhibition of the repair of photosystem II (PSII) by suppressing protein synthesis. In our present study, we generated transformants of Synechocystis that overexpressed a mutated form of EF-Tu, designated EF-Tu (C82S), in which Cys82 had been replaced by a Ser residue, and ROS-scavenging enzymes individually or together. Expression of EF-Tu (C82S) alone in Synechocystis enhanced the repair of PSII under strong light, with the resultant mitigation of PSII photoinhibition, but it stimulated the production of ROS. However, overexpression of superoxide dismutase and catalase, together with the expression of EF-Tu (C82S), lowered intracellular levels of ROS and enhanced the repair of PSII more significantly under strong light, via facilitation of the synthesis de novo of the D1 protein. By contrast, the activity of photosystem I was hardly affected in wild-type cells and in all the lines of transformed cells under the same strong-light conditions. Furthermore, transformed cells that overexpressed EF-Tu (C82S), superoxide dismutase, and catalase were able to survive longer under stronger light than wild-type cells. Thus, the reinforced capacity for both protein synthesis and ROS scavenging allowed both photosynthesis and cell proliferation to tolerate strong light.

Establishment and characterization of a muscle cell line from golden pompano (Trachinotus ovatus) and its application in viral susceptibility

A new cell line, golden pompano muscle (GPM), was developed and characterized from the muscle tissue of the golden pompano in this work. GPM cells were mostly fibroblast-like and proliferated well in Leibovitz's L-15 medium supplemented with fetal bovine serum (FBS) (concentration of 10% to 20%) at 28 °C. The cell line has been stably passed over 80 generations and has been successfully cryopreserved. Molecular characterization of cytochrome oxidase subunit I (COI) confirmed that the GPM cells used in this study were from the golden pompano. Chromosome analysis showed that the diploid chromosome number of GPM cells was 2 N = 48. The enhanced green fluorescent protein (EGFP) reporter gene was successfully expressed in the GPM cell line by liposome transfection technique, and the transfection efficiency of GPM cells was about 60%, which suggests that GPM cells are available for research on gene expression in vitro. Virus susceptibility assay showed that GPM cells were susceptible to red-spotted grouper nervous necrosis virus (RGNNV), evidenced by the occurrence of cytopathic effect (CPE) and the increased viral protein synthesis capacity. Furthermore, viral replication significantly increased the expression levels of interferon (IFN) related signaling molecules and pro-inflammatory cytokines in cells. Therefore, our work developed and characterized a new cell line from golden pompano muscle, which allowed for functional studies of genetic manipulation, viral pathogenesis, and the interactions of host and virus.

Evolutionary Adaptation of Protein Turnover in White Muscle of Stenothermal Antarctic Fish: Elevated Cold Compensation at Reduced Thermal Responsiveness.

Protein turnover is highly energy consuming and overall relates to an organism's growth performance varying largely between species, e.g., due to pre-adaptation to environmental characteristics such as temperature. Here, we determined protein synthesis rates and capacity of protein degradation in white muscle of the cold stenothermal Antarctic eelpout (Pachycara brachycephalum) and its closely related temperate counterpart, the eurythermal common eelpout (Zoarces viviparus). Both species were exposed to acute warming (P. brachycephalum, 0 °C + 2 °C day-1; Z. viviparus, 4 °C + 3 °C day-1). The in vivo protein synthesis rate (Ks) was monitored after injection of 13C-phenylalanine, and protein degradation capacity was quantified by measuring the activity of cathepsin D in vitro. Untargeted metabolic profiling by nuclear magnetic resonance (NMR) spectroscopy was used to identify the metabolic processes involved. Independent of temperature, the protein synthesis rate was higher in P. brachycephalum (Ks = 0.38-0.614 % day-1) than in Z. viviparus (Ks= 0.148-0.379% day-1). Whereas protein synthesis remained unaffected by temperature in the Antarctic species, protein synthesis in Z. viviparus increased to near the thermal optimum (16 °C) and tended to fall at higher temperatures. Most strikingly, capacities for protein degradation were about ten times higher in the Antarctic compared to the temperate species. These differences are mirrored in the metabolic profiles, with significantly higher levels of complex and essential amino acids in the free cytosolic pool of the Antarctic congener. Together, the results clearly indicate a highly cold-compensated protein turnover in the Antarctic eelpout compared to its temperate confamilial. Constant versus variable environments are mirrored in rigid versus plastic functional responses of the protein synthesis machinery.

PB0395 De Novo Protein Synthesis Capacity of Tumor-Educated Platelets

PB0395 De Novo Protein Synthesis Capacity of Tumor-Educated Platelets

HULL’S MAGIC BOX: BUILDING THE CASE FOR CLINICAL TRIALS USING ARGININE METHYLATION INHIBITORS AGAINST GBM

Abstract AIMS • Assess/evaluate transcriptomic changes in GBM, maintained on a microfluidics system, in response to treatment with arginine methylation inhibitor GSK3368715, currently in clinical trials, to identify novel therapeutic strategies, synergising with personalised patient care and precision medicine • Investigate molecular differences between healthy brain and GBM maintained on-chip in response to GSK3368715, including proliferation, apoptosis and splicing. METHOD GBM biopsies from Hull Royal Infirmary, or healthy mouse brain tissues, were maintained on-chip for 8- days and perfused with GSK3368715-treated media, at 3 μl/min, mimicking the in vivo environment. RNA- sequencing determined thousands of differentially expressed genes and alternative splicing (AS) events resulting from GSK3368715 treatment. Immunohistochemistry displayed the effect of GSK3368715 on healthy mouse brain tissue to ascertain the specificity of the arginine methylation inhibitor in leading to GBM apoptosis. RESULTS RNA-sequencing showed highly significant GO-term-enrichment in ribosome and translation pathways, suggesting decreased protein synthesis capacity after GSK3368715 treatment. Additionally, several hundreds of genes were found to be undergoing AS, compatible with a mechanism where changes in the arginine methylation pattern of spliceosome member FUS, upon GSK3368715 treatment, contribute to AS. Of these events, 136 (more than expected by chance, χ2 = 7.16, p = 0.007) were known FUS splicing targets. GO-term-enrichment of these AS events was found in DNA damage and cell death . Together these results are consistent with immunohistological findings that GSK3368715 causes apoptosis in GBM-on-chip tissue, in a specific manner. CONCLUSIONS Our results highlight an exciting potential therapeutic target for GBM, via induction of alternative splicing path- ways, through arginine methylation inhibition with GSK3368715.

Growth-rate dependency of ribosome abundance and translation elongation rate in Corynebacterium glutamicum differs from that in Escherichia coli

Bacterial growth rate (µ) depends on the protein synthesis capacity of the cell and thus on the number of active ribosomes and their translation elongation rate. The relationship between these fundamental growth parameters have only been described for few bacterial species, in particular Escherichia coli. Here, we analyse the growth-rate dependency of ribosome abundance and translation elongation rate for Corynebacterium glutamicum, a gram-positive model species differing from E. coli by a lower growth temperature optimum and a lower maximal growth rate. We show that, unlike in E. coli, there is little change in ribosome abundance for µ <0.4 h−1 in C. glutamicum and the fraction of active ribosomes is kept above 70% while the translation elongation rate declines 5-fold. Mathematical modelling indicates that the decrease in the translation elongation rate can be explained by a depletion of translation precursors.

Understanding the internal differences behind unsynchronized growth in sea cucumber Holothuria leucospilota by integration of transcriptomic and metabolomic data

In China, there is a rapidly increasing need for the seedlings of tropical sea cucumber, Holothuria leucospilota, as they are often used for releasing to restore fishery resources and marine environments. Unsynchronized growth (NG) of H. leucospilota has been a problem during its culture, and the molecular mechanisms behind NG are rarely explored. In the present study, unsynchronized growing seedlings of H. leucospilota cultured in same environment were random collected after 100 days rearing, and they were classified into a fast-growing (FG) group and a slow-growing (SG) group based on their body weight. Body wall tissues were sheared for metabolomic analysis based on liquid chromatography–tandem mass spectrometry (LC–MS/MS) and transcriptomic analysis with RNA sequencing (RNA-seq). 3243 Differentially expressed genes (DEGs) and 1574 different metabolites (DMs) were identified between two group. Integrated metabolomic and transcriptomic analysis revealed 47 jointly enriched pathways and the FG group had a better capacity for protein and fatty acid synthesis, vitamin synthesis, and oxidative stress regulatory while the SG group experienced more frequent apoptosis. The results facilitate to discover underlying mechanism of NG, which offers prospective benefits for the aquaculture of sea cucumbers.

Post-natal muscle growth and protein turnover: a narrative review of current understanding.

A model explaining the dietary-protein-driven post-natal skeletal muscle growth and protein turnover in the rat is updated, and the mechanisms involved are described, in this narrative review. Dietary protein controls both bone length and muscle growth, which are interrelated through mechanotransduction mechanisms with muscle growth induced both from stretching subsequent to bone length growth and from internal work against gravity. This induces satellite cell activation, myogenesis and remodelling of the extracellular matrix, establishing a growth capacity for myofibre length and cross-sectional area. Protein deposition within this capacity is enabled by adequate dietary protein and other key nutrients. After briefly reviewing the experimental animal origins of the growth model, key concepts and processes important for growth are reviewed. These include the growth in number and size of the myonuclear domain, satellite cell activity during post-natal development and the autocrine/paracrine action of IGF-1. Regulatory and signalling pathways reviewed include developmental mechanotransduction, signalling through the insulin/IGF-1-PI3K-Akt and the Ras-MAPK pathways in the myofibre and during mechanotransduction of satellite cells. Likely pathways activated by maximal-intensity muscle contractions are highlighted and the regulation of the capacity for protein synthesis in terms of ribosome assembly and the translational regulation of 5-TOPmRNA classes by mTORC1 and LARP1 are discussed. Evidence for and potential mechanisms by which volume limitation of muscle growth can occur which would limit protein deposition within the myofibre are reviewed. An understanding of how muscle growth is achieved allows better nutritional management of its growth in health and disease.

Insights into the Functional Components in Wheat Grain: Spatial Pattern, Underlying Mechanism and Cultivation Regulation.

Wheat is a staple crop; its production must achieve both high yield and good quality due to worldwide demands for food security and better quality of life. It has been found that the grain qualities vary greatly within the different layers of wheat kernels. In this paper, the spatial distributions of protein and its components, starch, dietary fiber, and microelements are summarized in detail. The underlying mechanisms regarding the formation of protein and starch, as well as spatial distribution, are discussed from the views of substrate supply and the protein and starch synthesis capacity. The regulating effects of cultivation practices on gradients in composition are identified. Finally, breakthrough solutions for exploring the underlying mechanisms of the spatial gradients of functional components are presented. This paper will provide research perspectives for producing wheat that is both high in yield and of good quality.