Comparative effects of zinc hydroxy chloride, zinc sulfate, and zinc-methionine on egg quality and quantity traits in laying hens.

The aim of this experiment was to evaluate the effect of different levels of zinc supplements on egg quality and quantity traits as well as egg enrichment with zinc in laying hens from 40 to 50 weeks of age. A total of 240 Hy-line laying hens were distributed among eight treatments and five replications (six birds per replication). The control group received no zinc diet, while the other treatments were supplemented with varying levels of zinc sulfate (80, 120, and 160 mg/kg) or zinc hydroxy chloride (50, 75, and 100 mg/kg). An additional group of zinc-methionine supplement at 124 mg/kg was also included. Results showed that different levels of zinc supplementation caused a significant improvement in eggshell resistance, eggshell percentage, feed conversion ratio, and Haugh unit compared to the control group. Adding organic and hydroxy sources of zinc significantly increased zinc contents in egg yolk, tibia bone, and blood. In addition, the treatments containing zinc supplements caused an increase in the antibody level against the Newcastle disease compared to the control (P < 0.05). Different levels and sources of zinc had no significant effect on eggshell thickness, specific gravity, and egg mass. Results showed that adding zinc in hydroxy chloride form at 100 mg/kg could improve performance indices, safety, and egg enrichment with zinc.

L-methionine and the L-type Ca2+ channel agonist BAY K 8644 collaboratively contribute to the reduction of depressive-like behavior in mice.

The L-type Ca2+ channel (LTCC, also known as Cav1,2) is involved in the regulation of key neuronal functions, such as dendritic information integration, cell survival, and neuronal gene expression. Clinical studies have shown an association between L-type calcium channels and the onset of depression, although the precise mechanisms remain unclear. The development of depression results from a combination of environmental and genetic factors. DNA methylation, a significant epigenetic modification, plays a regulatory role in the pathogenesis of psychiatric disorders such as posttraumatic stress disorder (PTSD), depression, and autism. In our study, we observed reduced Dnmt3a expression levels in the hippocampal DG region of mice with LPS-induced depression compared to control mice. The antidepressant Venlafaxine was able to increase Dnmt3a expression levels. Conversely, Bay K 8644, an agonist of the L-type Ca2+ channel, partially ameliorated depression-like behaviors but did not elevate Dnmt3a expression levels. Furthermore, when we manipulated DNA methylation levels during Bay K 8644 intervention in depression-like models, we found that enhancing the expression of Dnmt3a could improve LPS-induced depression/anxiety-like behaviors, while inhibiting DNA methylation exacerbated anxiety-like behaviors, the combined use of BAY K 8644 and L-methionine can better improve depressive-like behavior. These findings indicate that DNA methylation plays a role in the regulation of depression-like behaviors by the L-type Ca2+ channel, and further research is needed to elucidate the interactions between DNA methylation and L-type Ca2+ channels.

Nutritional vitamin B12 regulates RAS/MAPK-mediated cell fate decisions through one-carbon metabolism.

Vitamin B12 is an essential nutritional co-factor for the folate and methionine cycles, which together constitute one-carbon metabolism. Here, we show that dietary uptake of vitamin B12 modulates cell fate decisions controlled by the conserved RAS/MAPK signaling pathway in C. elegans. A bacterial diet rich in vitamin B12 increases vulval induction, germ cell apoptosis and oocyte differentiation. These effects are mediated by different one-carbon metabolites in a tissue-specific manner. Vitamin B12 enhances via the choline/phosphatidylcholine metabolism vulval induction by down-regulating fat biosynthesis genes and increasing H3K4 tri-methylation, which results in increased expression of RAS/MAPK target genes. Furthermore, the nucleoside metabolism and H3K4 tri-methylation positively regulate germ cell apoptosis and oocyte production. Using mammalian cells carrying different activated KRAS and BRAF alleles, we show that the effects of methionine on RAS/MAPK-regulated phenotype are conserved in mammals. Our findings suggest that the vitamin B12-dependent one-carbon metabolism is a limiting factor for diverse RAS/MAPK-induced cellular responses.

Optimizing the fermentation parameters in the Lactic Acid Fermentation of Legume-based Beverages- a statistically based fermentation.

BACKGROUND: The market for beverages is highly changing within the last years. Increasing consumer awareness towards healthier drinks led to the revival of traditional and the creation of innovative beverages. Various protein-rich legumes were used for milk analogues, which might be also valuable raw materials for refreshing, protein-rich beverages. However, no such applications have been marketed so far, which might be due to unpleasant organoleptic impressions like the legume-typical "beany" aroma. Lactic acid fermentation has already been proven to be a remedy to overcome this hindrance in consumer acceptance. RESULTS: In this study, a statistically based approach was used to elucidate the impact of the fermentation parameters temperature, inoculum cell concentration, and methionine addition on the fermentation of lupine- and faba bean-based substrates. A total of 39 models were found and verified. The majority of these models indicate a strong impact of the temperature on the reduction of aldehydes connected to the "beany" impression (e.g., hexanal) and on the production of pleasantly perceived aroma compounds (e.g., ß-damascenone). Positively, the addition of methionine had only minor impacts on the negatively associated sulfuric compounds methional, dimethyl sulfide, dimethyl disulfide, and dimethyl trisulfide. Moreover, in further fermentations, the time was added as an additional parameter. It was shown that the strains grew well, strongly acidified the both substrates (pH ≤ 4.0) within 6.5 h, and reached cell counts of > 9 log10 CFU/mL after 24 h. Notably, most of the aldehydes (like hexanal) were reduced within the first 6-7 h, whereas pleasant compounds like ß-damascenone reached high concentrations especially in the later fermentation (approx. 24-48 h). CONCLUSIONS: Out of the fermentation parameters temperature, inoculum cell concentration, and methionine addition, the temperature had the highest influence on the observed aroma and taste active compounds. As the addition of methionine to compensate for the legume-typical deficit did not lead to an adverse effect, fortifying legume-based substrates with methionine should be considered to improve the bioavailability of the legume protein. Aldehydes, which are associated with the "beany" aroma impression, can be removed efficiently in fermentation. However, terminating the process prematurely would lead to an incomplete production of pleasant aroma compounds.

Transcription factor condensates, 3D clustering, and gene expression enhancement of the MET regulon.

Some transcription factors (TFs) can form liquid-liquid phase separated (LLPS) condensates. However, the functions of these TF condensates in 3-Dimentional (3D) genome organization and gene regulation remain elusive. In response to methionine (met) starvation, budding yeast TF Met4 and a few co-activators, including Met32, induce a set of genes involved in met biosynthesis. Here, we show that the endogenous Met4 and Met32 form co-localized puncta-like structures in yeast nuclei upon met depletion. Recombinant Met4 and Met32 form mixed droplets with LLPS properties in vitro. In relation to chromatin, Met4 puncta co-localize with target genes, and at least a subset of these target genes is clustered in 3D in a Met4-dependent manner. A MET3pr-GFP reporter inserted near several native Met4-binding sites becomes co-localized with Met4 puncta and displays enhanced transcriptional activity. A Met4 variant with a partial truncation of an intrinsically disordered region (IDR) shows less puncta formation, and this mutant selectively reduces the reporter activity near Met4-binding sites to the basal level. Overall, these results support a model where Met4 and co-activators form condensates to bring multiple target genes into a vicinity with higher local TF concentrations, which facilitates a strong response to methionine depletion.

Ctr9 promotes virulence of Candida albicans by regulating methionine metabolism.

Candida albicans, a part of normal flora, is an opportunistic fungal pathogen and causes severe health issues in immunocompromised patients. Its pathogenicity is intricately linked to the transcriptional regulation of its metabolic pathways. Paf1 complex (Paf1C) is a crucial transcriptional regulator that is highly conserved in eukaryotes. The objective of this study was to explore the role of Paf1C in the metabolic pathways and how it influences the pathogenicity of C. albicans. Paf1C knockout mutant strains of C. albicans (ctr9Δ/Δ, leo1Δ/Δ, and cdc73Δ/Δ) were generated using the CRISPR-Cas9 system. To investigate the effect of Paf1C on pathogenicity, macrophage interaction assays and mouse survival tests were conducted. The growth patterns of the Paf1C knockout mutants were analyzed through spotting assays and growth curve measurements. Transcriptome analysis was conducted under yeast conditions (30°C without serum) and hyphal conditions (37°C with 10% FBS), to further elucidate the role of Paf1C in the pathogenicity of C. albicans. CTR9 deletion resulted in the attenuation of C. albicans virulence, in macrophage and mouse models. Furthermore, we confirmed that the reduced virulence of the ctr9Δ/Δ mutant can be attributed to a decrease in C. albicans cell abundance. Moreover, transcriptome analysis revealed that metabolic processes required for cell proliferation are impaired in ctr9Δ/Δ mutant. Notably, CTR9 deletion led to the downregulation of methionine biosynthetic genes and the cAMP-PKA signaling pathway-related hypha essential genes, which are pivotal for virulence. Our results suggest that Ctr9-regulated methionine metabolism is a crucial factor for determining C. albicans pathogenicity.

Rumen-protected methionine supplementation during the transition period under artificially induced heat stress: Effects on cow-calf performance.

Dairy cows experiencing heat stress (HS) during the precalving portion of the transition period give birth to smaller calves and produce less milk and milk protein. Supplementation of rumen-protected methionine (RPM) has been shown to modulate protein, energy, and placenta metabolism, making it a potential candidate to ameliorate HS effects. We investigated the effects of supplementing RPM to transition cows under HS induced by electric heat blanket (EHB) on cow-calf performance. Six weeks before expected calving, 53 Holstein cows were housed in a tiestall barn and fed a control diet (CON, 2.2% Met of MP) or a CON diet supplemented with SmartamineM (MET, 2.6% Met of MP, Adisseo Inc., France). Four weeks precalving, all MET and half CON cows were fitted with an EHB. The other half of the CON cows were considered thermoneutral (TN), resulting in 3 treatments: CONTN (n = 19), CONHS (n = 17), and METHS (n = 17). Respiratory rate (RR), skin temperature (ST), and rectal temperature (RT) were measured thrice weekly and core body temperatures recorded biweekly. Postcalving BW and BCS were recorded weekly, and DMI was calculated and averaged weekly. Milk yield was recorded daily and milk components were analyzed every third DIM. Biweekly AA and weekly nonesterified fatty acids (NEFA), BHB, insulin, and glucose were measured from plasma. Calf birth weight and 24 h growth, thermoregulation, and hematology profile were measured and apparent efficiency of absorption (AEA) of immunoglobulins was calculated. Data were analyzed using the MIXED procedure of SAS with 2 preplanned orthogonal contrasts: CONTN versus the average of CONHS and METHS (C1) and CONHS versus METHS (C2). Relative to TN, EHB cows had increased RT during the postcalving weeks and increased RR and ST during the entire transition period. Body weight, BCS, DMI, and milk yield were not affected by the EHB or RPM. However, protein percentage and SNF were lower in CONHS, relative to METHS cows. At calving, METHS dams had higher glucose concentrations, relative to CONHS, and during the postcalving weeks, the EHB cows had lower NEFA concentrations than TN cows. Calf birthweight and AEA were reduced by HS, whereas RR was increased by HS. Calf withers height tended to be shorter and RT were lower in CONHS, compared with METHS heifers. Overall, RPM supplementation to transition cows reverts the negative effect of HS on blood glucose concentration at calving and milk protein percentage in the dams and increases wither height while decreasing RT in the calf.

Multi-protein assemblies orchestrate co-translational enzymatic processing on the human ribosome.

Nascent chains undergo co-translational enzymatic processing as soon as their N-terminus becomes accessible at the ribosomal polypeptide tunnel exit (PTE). In eukaryotes, N-terminal methionine excision (NME) by Methionine Aminopeptidases (MAP1 and MAP2), and N-terminal acetylation (NTA) by N-Acetyl-Transferase A (NatA), is the most common combination of subsequent modifications carried out on the 80S ribosome. How these enzymatic processes are coordinated in the context of a rapidly translating ribosome has remained elusive. Here, we report two cryo-EM structures of multi-enzyme complexes assembled on vacant human 80S ribosomes, indicating two routes for NME-NTA. Both assemblies form on the 80S independent of nascent chain substrates. Irrespective of the route, NatA occupies a non-intrusive 'distal' binding site on the ribosome which does not interfere with MAP1 or MAP2 binding nor with most other ribosome-associated factors (RAFs). NatA can partake in a coordinated, dynamic assembly with MAP1 through the hydra-like chaperoning function of the abundant Nascent Polypeptide-Associated Complex (NAC). In contrast to MAP1, MAP2 completely covers the PTE and is thus incompatible with NAC and MAP1 recruitment. Together, our data provide the structural framework for the coordinated orchestration of NME and NTA in protein biogenesis.

Re-routing MAP kinase signaling for penetration peg formation in predator yeasts.

Saccharomycopsis yeasts are natural organic sulfur auxotrophs due to lack of genes required for the uptake and assimilation of sulfate/sulfite. Starvation for methionine induces a shift to a predatory, mycoparasitic life strategy that is unique amongst ascomycetous yeasts. Similar to fungal plant pathogens that separated from Saccharomycopsis more than 400 million years ago, a specialized infection structure called penetration peg is used for prey cell invasion. Penetration pegs are highly enriched with chitin. Here we demonstrate that an ancient and conserved MAP kinase signaling pathway regulates penetration peg formation and successful predation in the predator yeast S. schoenii. Deletion of the MAP kinase gene SsKIL1, a homolog of the Saccharomyces cerevisiae ScKSS1/ScFUS3 and the rice blast Magnaporthe oryzae MoPMK1 genes, as well as deletion of the transcription factor SsSTE12 generate non-pathogenic mutants that fail to form penetration pegs. Comparative global transcriptome analyses using RNAseq indicate loss of the SsKil1-SsSte12-dependent predation response in the mutant strains, while a methionine starvation response is still executed. Within the promoter sequences of genes upregulated during predation we identified a cis-regulatory element similar to the ScSte12 pheromone response element. Our results indicate that, re-routing MAP-kinase signaling by re-wiring Ste12 transcriptional control towards predation specific genes contributed to the parallel evolution of this predacious behaviour in predator yeasts. Consequently, we found that SsSTE12 is dispensable for mating.

Size matters: lower body weight pigs have a different response to immune challenge and amino acids supplementation above the estimated requirement compared to heavy pigs.

The immune response varies between pigs, as not all pigs have the same response to a stressor. This variation may exist between individuals due to body weight (BW) or body composition, which may impact the capacity for coping with an immune challenge (IC). Tryptophan (Trp), threonine (Thr), and methionine (Met) requirements might also play a considerable part in supporting immune system activation while reducing variation between pigs; however, the latter has yet to be reported. This exploratory study investigated the effect of initial BW (light vs. heavy-weight) and supplementation of Trp, Thr, and Met above National Research Council (NRC) requirements on feeding behavior and the coping capacity of growing pigs under an IC. Eighty gilts were categorized into 2 groups according to BW: light-weight (LW, 22.5 kg) and heavy-weight pigs (HW, 28.5 kg). Both BW groups were group-housed for a 28-d trial in a good or poor sanitary condition (SC). Pigs within a poor SC were orally inoculated with 2 × 109 colony units of Salmonella Typhimurium, and fresh manure from a pig farm was spread on the floor. Pigs within good SC were not inoculated, nor was manure spread. Two diets were provided within each SC: control (CN) or supplemented (AA+) with Trp, Thr, and Met at 120% of NRC recommended levels. A principal component analysis was performed in R, and a feeding behavior index was calculated in SAS. Results showed that LW and HW pigs were clustered separately on day 0, where LW pigs had a positive correlation with body lipid percentage (r = 0.83), and HW pigs had a positive correlation with body protein percentage (r = 0.75). After the IC, the cluster configuration changed, with diets influencing LW more than HW pigs within poor SC. On day 14, LW fed AA + diet in poor SC was clustered separately from LW pigs fed CN diet, whereas LW fed AA + and CN diets in good SC were clustered together. For feeding behavior, in both analyzed periods (period 1: days 7 to 14; period 2: days 21 to 28), LW had lower total feed intake and shorter meals than HW pigs (P < 0.10), independent of the SC. Furthermore, LW pigs fed AA + diet had a more regular feed intake pattern than those fed CN diet, while a more irregular pattern was observed for HW pigs fed AA + diet than CN diet at period 2. These findings suggest that supplementing Trp, Thr, and Met above requirements may be a nutritional strategy for LW pigs under IC by improving feed intake regularity and reducing the probability of being susceptible to IC.

An immune challenge impacts pig welfare and may decrease growth and protein deposition. These may happen due to the different nutrient requirements of immune-challenged pigs compared to non-challenged. Dietary supplementation of tryptophan, threonine, and methionine has been proven to be a strategy to mitigate performance losses by supporting immune system functioning, maintaining gut barrier integrity, and reducing oxidative status. However, individuals within a population with similar age and genetics have distinct responses to dietary strategies due to different coping abilities to an immune challenge, which may be due to body weight (BW)/body composition and feeding behavior patterns. In this context, this study investigated the effect of BW (light-weight vs. heavy-weight) and tryptophan, threonine, and methionine supplementation on feeding behavior and the coping capacity of growing pigs under an immune challenge. Heavy-weight pigs had greater feed intake regularity and coping abilities over time when compared to light-weight pigs. However, increasing the amino acid level in the diet improved feed intake regularity in light-weight pigs. The amino acid supplementation may be a potential precision nutrition strategy for light-weight pigs by improving feed intake regularity over time, reducing susceptibility to an immune challenge.

First-line Chemotherapy in Combination With Oral Recombinant Methioninase and a Low-methionine Diet for a Stage IV Inoperable Pancreatic-Cancer Patient Resulted in 40% Tumor Reduction and an 86% CA19-9 Biomarker Decrease.

BACKGROUND/AIM: Pancreatic cancer has a very poor prognosis with a 5-year survival rate of less than 5% among patients with distant metastasis, a figure that has not improved over many decades. Only 10 to 20% patients are candidates for curative surgery at presentation due to the aggressive nature and asymptomatic progression of pancreatic cancer. Although first-line chemotherapy, such as FOLFIRINOX and gemcitabine + nab paclitaxel, improved the median survival from 8.5 to 11.1 months, more effective treatments are immediately needed. The aim of the present study was to evaluate the efficacy of methionine restriction with oral rMETase (o-rMETase) and a low-methionine diet combined with first-line chemotherapy on a patient with stage IV metastatic pancreatic cancer. CASE REPORT: A 63-year-old female was diagnosed with metastatic pancreatic cancer in October 2023. The patient started FOLFIRINOX as first-line chemotherapy in combination with methionine restriction, which comprised o-rMETase 250 units twice a day and a low-methionine diet. The patient was monitored using computed tomography and CA19-9 blood tests. After five months from the start of combination therapy, the size of the primary tumor decreased by 40% along with liver-metastasis regression. The CA19-9 blood marker decreased by 86%. The patient sustains a high performance status and continues the combination therapy without severe side effects. CONCLUSION: Methionine restriction consisting of o-rMETase and a low-methionine diet, in combination with first-line chemotherapy, was highly effective in a patient with inoperable stage IV pancreatic cancer.

[11C]Methionine PET vs. [18F]Fluorodeoxyglucose PET Whole-body Imaging to Determine the Extent of Methionine-addiction Compared to Glucose-addiction of Primary and Metastatic Cancer of the Trunk in Patients.

BACKGROUND/AIM: Positron emission tomography (PET) is an important imaging modality, especially in oncology. [18F]fluorodeoxyglucose PET (FDG-PET) is the most used cancer PET imaging. However, since the elevated glucose use by cancers, termed the Warburg effect, is usually only moderate, FDG often does not provide a strong or well-delineated signal. Malignancies have a stronger addiction to methionine, known as the Hoffman effect, and thus [11C]methionine PET (MET-PET) has demonstrated superiority over FDG-PET in gliomas and other brain tumors. Our team is pioneering the use of MET-PET for tumors of the trunk for both better detection of cancer and to determine candidates for methionine-restriction therapy. The present study provides examples of cancers of organs in the trunk in which MET-PET outperforms FDG-PET in detecting and delineating primary and metastatic cancer. PATIENTS AND METHODS: In all cases, MET-PET and FDG-PET were performed simultaneously. An evaluation of the images was conducted by a nuclear medicine physician. RESULTS: Four cases, including prostate, bladder, esophageal, and breast cancer demonstrated the superiority of MET-PET compared to FDG-PET. CONCLUSION: MET-PET can out-perform FDG PET for accurate detection of primary and metastatic cancer in the trunk and can determine the extent of methionine addiction of cancer, thereby indicating whether cancer patients can benefit from methionine-restriction therapy.

Late-Stage Glycosylation of Peptides by Methionine-Directed ß-C(sp3)-H Functionalization with 1-Iodoglycals.

Using l-methionine (Met) as the endogenous directing group, we developed Pd-catalyzed ß-C(sp3)-H glycosylation of peptides with 1-iodoglycals. A wide range of tri- to hexapeptides containing the Ala-Met motifs underwent Ala C-H glycosylation under the standard conditions to give the glycopeptides smoothly. 15 proteinogenic amino acids (with easily removable protecting groups) were well tolerated. Control experiments indicated that Met acted as a N,S-bidentate directing group and exhibited an effect superior to other amino acid residues such as l-aspartic acid (Asp), l-asparagine (Asn), and S-protected l-cysteine (Cys). In addition, further transformation by HFIP-promoted 1,4-elimination furnished another type of glycopeptide with the 1,3-diene motif, which provides a handle for further derivatization.

Conserved gatekeeper methionine regulates the binding and access of kinase inhibitors to ATP sites of MAP2K1, 4, and 7: Clues for developing selective inhibitors.

Mitogen-activated protein kinase kinases (MAP2Ks) 1, 4, and 7 are potential targets for treating various diseases. Here, we solved the crystal structures of MAP2K1 and MAP2K4 complexed with covalent inhibitor 5Z-7-oxozeaenol (5Z7O). The elucidated structures showed that 5Z7O was non-covalently bound to the ATP binding site of MAP2K4, while it covalently attached to cysteine at the DFG-1 position of the deep ATP site of MAP2K1. In contrast, we previously showed that 5Z7O covalently binds to MAP2K7 via another cysteine on the solvent-accessible edge of the ATP site. Structural analyses and molecular dynamics calculations indicated that the configuration and mobility of conserved gatekeeper methionine located at the central ATP site regulated the binding and access of 5Z7O to the ATP site of MAP2Ks. These structural features provide clues for developing highly potent and selective inhibitors against MAP2Ks. Abbreviations: ATP, adenosine triphosphate; FDA, Food and Drug Administration; MAP2Ks, mitogen-activated protein kinase kinases; MD, molecular dynamics; NSCLC, non-small cell lung cancer; 5Z7O, 5Z-7-oxozeaenol; PDB, protein data bank; RMSD, root-mean-square deviation.

Methionine represses gray mold of tomato by keeping nitric oxide at an appropriate level via ethylene synthesis and signal transduction.

Methionine (Met) can inhibit plant diseases caused by phytopathogens. However, the effect of Met on gray mold resulted from Botrytis cinerea in tomato is still unclear. This study showed 5 mM Met alleviated disease development of gray mold, enhanced chitinase (CHI) and ß-1, 3-glucanase (GNS) activities and the expression of SlCHI, SlGNS, SlPR1 and SlNPR1 in tomatoes, rather than inhibited the growth of B. cinerea directly. Moreover, ethylene biosynthesis and signal transduction before pathogen inoculating were induced by 5 mM Met. Interestingly, Met reduced the nitrosylation levels of ACS4 and ACO6, enhanced the activities of nitric oxide synthase, nitrite reductase (NR) and S-nitrosoglutathione reductase (GSNOR) and the expression of SlNR and SlGSNOR. Tomatoes treated with aminoethoxyvinylglycine and carboxy-PTIO exhibited lower resistance to B. cinerea. These results indicate 5 mM Met promoted ethylene biosynthesis and signal transduction to facilitate NO synthesis and metabolism, enhancing the resistance of tomatoes to B. cinerea.

Investigation of guanidino acetic acid and rumen-protected methionine induced improvements in longissimus lumborum muscle quality in beef cattle.

This study examined the impact of dietary guanidino acetic acid (GAA) and rumen-protected methionine (RPM) on beef quality in Simmental bulls. For 140 days, forty-five bulls (453.43 ± 29.05 kg) were randomly divided into control (CON), 0.1% GAA (GAA), and 0.1% GAA + 0.1% RPM (GAM) groups with 15 bulls in each group and containing 3 pen with 5 bulls in each pen. Significant improvements in eye muscle area, pH48h, redness (a*) value, and crude protein (CP) content of longissimus lumborum (LL) muscles were observed in the GAA and GAM groups (P < 0.05). Conversely, the lightness (L*) value, drip loss, cooking loss, and moisture contents decreased (P < 0.05). Additionally, glutathione (GSH) and glutathione peroxidase (GSH-PX) concentrations of LL muscles in GAM were higher (P < 0.05), while malondialdehyde (MDA) content of LL muscles in GAA and GAM groups were lower (P < 0.05). Polyunsaturated fatty acids (PUFA) profiles were enriched in beef from GAM group (P < 0.05). The addition of GAA and RPM affected the expression of genes in LL muscle, such as HMOX1, EIF4E, SCD5, and NOS2, which are related to hypoxia metabolism, protein synthesis, and unsaturated fatty acid synthesis-related signaling pathways. In addition, GAA and RPM also affected the content of a series of metabolites such as L-tyrosine, L-tryptophan, and PC (O-16:0/0:0) involved in amino acid and lipid metabolism-related signaling pathways. In summary, GAA and RPM can improve the beef quality and its nutritional composition. These changes may be related to changes in gene expression and metabolic pathways related to protein metabolism and lipid metabolism in beef.

NAC guides a ribosomal multienzyme complex for nascent protein processing.

Approximately 40% of the mammalian proteome undergoes N-terminal methionine excision and acetylation, mediated sequentially by methionine aminopeptidase (MetAP) and N-acetyltransferase A (NatA), respectively1. Both modifications are strictly cotranslational and essential in higher eukaryotic organisms1. The interaction, activity and regulation of these enzymes on translating ribosomes are poorly understood. Here we perform biochemical, structural and in vivo studies to demonstrate that the nascent polypeptide-associated complex2,3 (NAC) orchestrates the action of these enzymes. NAC assembles a multienzyme complex with MetAP1 and NatA early during translation and pre-positions the active sites of both enzymes for timely sequential processing of the nascent protein. NAC further releases the inhibitory interactions from the NatA regulatory protein huntingtin yeast two-hybrid protein K4,5 (HYPK) to activate NatA on the ribosome, enforcing cotranslational N-terminal acetylation. Our results provide a mechanistic model for the cotranslational processing of proteins in eukaryotic cells.

Alterations in one­carbon metabolism and protein synthesis signals due to methionine supplementation and lipopolysaccharide challenge in Holstein fetal liver explants.

One­carbon metabolism (OCM) fueled by methionine (Met), choline, and folic acid is key for embryo development and fetal growth. We investigated effects of lipopolysaccharide (LPS) to induce inflammation in fetal liver tissue with or without Met on components of OCM and protein synthesis activity. Fetal liver harvested at slaughter from six multiparous pregnant Holstein dairy cows (37 ± 6 kg milk/d, 100 ± 3 d gestation) were incubated (0.2 ± 0.02 g) for 4 h at 37 °C with each of the following: ideal profile of amino acids (control; Lysine:Met 2.9:1), control plus LPS (1 µg/mL), increased Met supply (Met, Lys:Met 2.5:1), and Met+LPS. Data were analyzed as a 2 × 2 factorial (PROC MIXED, SAS 9.4). Ratios of mechanistic target of rapamycin (p-mTOR:mTOR) and eukaryotic elongation factor 2 (p-eEF2:eEF2) protein were lowest (P < 0.0 5) with LPS and highest with Met. Tissue amino acid concentrations were lowest (P < 0.0 5) with Met regardless of LPS suggesting enhanced use via mTOR. The marked increase (P = 0.02) in phosphorylation of S6 ribosomal protein (p-RPS6) with LPS suggested a pro-inflammatory response that was partly alleviated with Met+LPS. No effect (P = 0.4 5) on methionine adenosyl transferase 1 A (MAT1A) protein abundance was detected. Activity of betaine-homocysteine S-methyltransferase (BHMT) was greatest with Met, but Met+LPS dampened this effect (P = 0.0 5). Overall, fetal liver responds to inflammatory challenges and Met supply. The latter can stimulate protein synthesis via mTOR and alter some OCM reactions while having a modest anti-inflammatory effect.

Bacteria modulate microalgal aging physiology through the induction of extracellular vesicle production to remove harmful metabolites.

The bloom and bust patterns of microalgae in aquatic systems contribute massively to global biogeochemical cycles. The decline of algal blooms is mainly caused by nutrient limitation resulting in cell death, the arrest of cell division and the aging of surviving cells. Nutrient intake can re-initiate proliferation, but the processes involved are poorly understood. Here we characterize how the bloom-forming diatom Coscinodiscus radiatus recovers from starvation after nutrient influx. Rejuvenation is mediated by extracellular vesicles that shuttle reactive oxygen species, oxylipins and other harmful metabolites out of the old cells, thereby re-enabling their proliferation. By administering nutrient pulses to aged cells and metabolomic monitoring of the response, we show that regulated pathways are centred around the methionine cycle in C. radiatus. Co-incubation experiments show that bacteria mediate aging processes and trigger vesicle production using chemical signalling. This work opens new perspectives on cellular aging and rejuvenation in complex microbial communities.

A methionine-choline-deficient diet induces nonalcoholic steatohepatitis and alters the lipidome, metabolome, and gut microbiome profile in the C57BL/6J mouse.

The methionine-choline-deficient (MCD) diet-induced non-alcoholic steatohepatitis (NASH) in mice is a well-established model. Our study aims to elucidate the factors influencing liver pathology in the MCD mouse model by examining physiological, biochemical, and molecular changes using histology, molecular techniques, and OMICS approaches (lipidomics, metabolomics, and metagenomics). Male C57BL/6J mice were fed a standard chow diet, a methionine-choline-sufficient (MCS) diet, or an MCD diet for 10 weeks. The MCD diet resulted in reduced body weight and fat mass, along with decreased plasma triglyceride, cholesterol, glucose, and insulin levels. However, it notably induced steatosis, inflammation, and alterations in gene expression associated with lipogenesis, inflammation, fibrosis, and the synthesis of apolipoproteins, sphingolipids, ceramides, and carboxylesterases. Lipid analysis revealed significant changes in plasma and tissues: most ceramide non-hydroxy-sphingosine lipids significantly decreased in the liver and plasma but increased in the adipose tissue of MCD diet-fed animals. Oxidized glycerophospholipids mostly increased in the liver but decreased in the adipose tissue of the MCD diet-fed group. The gut microbiome of the MCD diet-fed group showed an increase in Firmicutes and a decrease in Bacteroidetes and Actinobacteria. Metabolomic profiling demonstrated that the MCD diet significantly altered amino acid biosynthesis, metabolism, and nucleic acid metabolism pathways in plasma, liver, fecal, and cecal samples. LC-MS data indicated higher total plasma bile acid intensity and reduced fecal glycohyodeoxycholic acid intensity in the MCD diet group. This study demonstrates that although the MCD diet induces hepatic steatosis, the mechanisms underlying NASH in this model differ from those in human NASH pathology.