Carbohydrate Oxidation Research Articles

Aging delays the suppression of lipolysis and fatty acid oxidation in the postprandial period.

Plasma glycerol and free fatty acid concentrations decrease following oral glucose consumption, but changes in the rate of lipolysis during an oral glucose tolerance test (OGTT) have not been documented in conjunction with changes in fatty acid (FA) oxidation or reesterification rates in healthy individuals. After a 12-h overnight fast, 15 young (21-35 yr; 7 men and 8 women) and 14 older (60-80 yr; 7 men and 7 women) participants had the forearm vein catheterized for primed continuous infusion of [1,1,2,3,3-2H]glycerol. A contralateral hand vein was catheterized for arterialized blood sampling. Indirect calorimetry was performed simultaneously to determine total FA and carbohydrate (CHO) oxidation rates (Rox). Total FA reesterification rates (Rs) were estimated from tracer-measured lipolytic and FA oxidation rates. After a 90-min equilibration period, participants underwent a 120-min, 75-g OGTT. Glycerol rate of appearance (Ra), an index of lipolysis, decreased significantly from baseline 5 min postchallenge in young participants and 30 min in older participants. At 60 min, FA Rox decreased in both groups, but was significantly higher in older participants. Between 5 and 90 min, CHO Rox was significantly lower in older participants. In addition, FA Rs was significantly lower in older participants at 60 and 90 min. The area under the curve (AUC) for FA Rox was greater than that for FA Rs in older, but not in young participants. Our results indicate that, in aging, the postprandial suppression of lipolysis and FA oxidation are delayed such that FA oxidation is favored over CHO oxidation and FA reesterification.NEW & NOTEWORTHY To our knowledge, our investigation is the first to demonstrate changes in lipolysis during an oral glucose tolerance test (OGTT) in healthy young and older individuals. Plasma glycerol and free fatty acid concentrations changed after glycerol rate of appearance (Ra), indicating that plasma concentrations are incomplete surrogates of the lipolytic rate. Moreover, simultaneous determinations of substrate oxidation rates are interpreted to indicate that metabolic inflexibility in aging is characterized by delayed changes in postprandial substrate utilization related to the lipolytic rate.

Preliminary study on the effects of boysenberry juice intake on brown adipose tissue activity in healthy adults

Brown adipose tissue (BAT) plays an important role in energy metabolism because it uses fatty acids for thermogenesis during cold exposure. Preclinical studies found that boysenberry anthocyanins (BoyACs) activate BAT. Therefore, the aim of this preliminary study was to evaluate how BoyAC intake affects BAT in humans. We performed an open-label single-arm nonrandomized study in healthy volunteers. Before and after 4 weeks of daily consumption of 100 ml boysenberry juice (BoyJ) containing 61 mg of BoyACs, participants were assessed at 24 °C and then after 1 h of mild cold exposure (18 °C). An infrared thermography camera was used to measure skin surface temperatures in the supraclavicular BAT region (Tscv) and the non-BAT region of the upper chest (Tch). Energy metabolism was measured by indirect calorimetry. For each endpoint, we calculated Δ as the difference between values before and after cold exposure and compared the values before and after BoyJ intake. 10 volunteers participated (age: 36.1 ± 4.1, body mass index (BMI): 20.9 ± 0.6). After BoyJ intake, ΔTscv-ch was significantly higher (p = 0.029), but Δ energy expenditure, Δ fat oxidation, and Δ carbohydrate oxidation were not significantly different. We found a significant positive correlation between BMI and Δfat oxidation with BoyJ intake. The results indicate that 4 weeks of BoyJ intake activates cold-induced thermogenesis in the scv-BAT but does not have a significant effect on energy metabolism. BoyJ intake may increase fat oxidation during cold exposure in individuals with higher BMI.Trial registry number: UMIN000043476, 05/03/2021.

Turn-off fluorescent nanoprobe based on carbon dots synthesised by UV/H2O2 advanced oxidation for the detection of bisphenol A in canned foods.

Anovel assay was developedbased on a turn-off fluorescent probe using the in situ generation of carbon dots (CDs) by means of UV/H2O2 advanced oxidation of carbohydrates for the detection of bisphenol A (BPA) in food. Different parameters involved in the synthesis of CDs for the direct recognition of BPA have been optimised and a sensing mechanism is outlined. The presence of H2O2 during CD synthesis causes a fluorescence enhancement due to the action of highly oxidant HO· radicals formed throughout the photochemical reaction. Phenolic compounds such as BPA can be easily degraded by the UV/H2O2 oxidation process, acting as a HO· free radical scavengers. This results in a decrease in the fluorescence that can be related to the BPA concentration. Under optimal conditions, a detection limit of 15µg/kg of BPA and a quantification limit of 46µg/kg of BPA in food sampleswere obtained. The repeatability and reproducibility, expressed as relative standard deviation and obtained for two concentration levels (30µg/kg and 200µg/kg, n = 5), were less than 2.0% and 6.4%, respectively. The proposed procedure was applied to the analysis of five samples of canned foods (sweet corn, peas, mushrooms, cockles and natural tuna), obtaining concentrations in the range 29.8-49.9µg/kg of sample. Recovery studies were conducted at two concentration levels (100and 400µgBPA/kg of sample), resulting in recoveries in the range 99-101%. Method validation against two certified reference materials was also successfully performed. The experimental results demonstrate that the novel approach is suitable for the detection and quantification of BPA in canned foods.

Females have better metabolic flexibility in different metabolically challenging stimuli.

The first aim was to explore the difference in metabolic flexibility between sexes in response to changing exercise intensity under control conditions. The second aim was to evaluate metabolic flexibility between sexes in response to exercise intensity adding two different metabolically challenging stimuli (glycogen depletion and heat). Eleven males (22±3yrs, 176.2±4cm, 68.4±4.9kg and 60.2±4.1ml/kgFFM/min) and nine females (22±2yrs, 166.7±4.5cm, 61.9±2.9kg, 64.2±5.6 ml/kgFFM/min) performed a maximal incremental exercise test (30W every 3min) on a cycle ergometer under three conditions: control (24h high-carbohydrate diet followed by the incremental test), glycogen depletion (glycogen-depletion protocol followed by 24h low-carbohydrate diet and then the incremental test) and heat (24h high-carbohydrate diet followed by 30 min passive heating and then the incremental test in heat). In the last minute of each step, lactate was analysed, fat (FATox/FFM) and carbohydrate oxidation (CHox/FFM) and energy expenditure (EE/FFM) normalized to fat free mass was estimated by indirect calorimetry. Females presented a greater FATox/FFM as exercise intensity increases across conditions (control, glycogen depletion and heat) (p=0.006). In contrast, CHox/FFM was not significantly different between sexes at any specific intensity across conditions (p>0.05). Consequently, EE/FFM was higher in females throughout the different intensities across conditions (p=0.002). Finally, lactate concentration was not different between sexes at the same intensities across conditions (p=0.87). In conclusion, females present a greater metabolic flexibility, due to the higher FATox/FFM throughout the different intensities, regardless of whether the test is performed in a conditions emphasizing the oxidative pathway (glycogen depletion) or the glycolytic pathway (heat). Clinical trials:NCT05703100.

Genetic Variation and Metabolic Basis of Kidney Cancer: New Opportunities for Targeted Therapy

Renal cell carcinoma (RCC) has previously been considered as a single disease. However, it is currently characterized as a heterogeneous group of tumors that differ in histological features, genetic abnormalities, and variable clinical course. In normal cells, energy is produced by the cleavage of chemical bonds in nutrients through the oxidation of fats, proteins, or carbohydrates. Mutational alterations in genes associated with RCC, including VHL, FLCN, PTEN and SDH, lead to abnormal cellular adaptation to changes in oxygen status, iron metabolism and nutrients. The present paper reviews the known genetic abnormalities observed in RCC and their impact on metabolic alterations. Understanding the genetic and metabolic mechanisms underlying RCC is crucial for the development of effective therapies. Targeting specific genetic abnormalities or metabolic pathways represents a promising approach to the RCC treatment. In addition, studies into the metabolic basis of RCC contribute to the development of new biomarkers for early diagnosis and monitoring of the disease. Moreover, investigating the role of VHL, FLCN, PTEN, and SDH genes in the development of RCC provides valuable information on the molecular mechanisms behind the disease. As a result, it may lead to the development of new treatment strategies aimed at restoring the normal function of these genes or compensating for their abnormalities. Overall, an integrated approach to the study of RCC that considers genetic, metabolic, and clinical aspects will ensure that more effective treatments are developed and prognosis for patients with this disease are improved.

9179 Type 2 Diabetes Alters Metabolic Fuel Selection During Intermittent Fasting

Abstract Disclosure: M.O. Conn: None. D.M. Marko: None. J.D. Schertzer: None. Type 2 Diabetes Alters Metabolic Fuel Selection During Intermittent Fasting Diabetes is characterized by elevated blood glucose resulting from defective insulin secretion and/or insulin resistance. Intermittent fasting, a popular weight loss strategy involving periodic reduction of caloric intake, can improve glycemia. Fasting shifts metabolism from carbohydrates to free fatty acids and ketones. However, high blood insulin can inhibit lipolysis and alter metabolic substrate selection in prediabetes, resulting in muscle catabolism to maintain energy homeostasis. Clinical studies have observed a significant decrease in muscle mass in subjects with obesity and diabetes. Our research aims to characterize lean mass versus fat loss after intermittent fasting in a mouse model of obesity and type 2 diabetes (T2D) and investigate the role of muscle alanine catabolism. We hypothesized that intermittent fasting would promote less lipolysis and more muscle alanine catabolism, causing more muscle loss in diabetic mice than controls. We compared male db/db mice manifesting obesity, hyperglycemia, and hyperinsulinemia to age-matched db/+ (control) mice. Our lab established a 5:2 repeated fasting protocol of ad-libitum access to food for 5 days a week and 2 days of fasting on non-consecutive days. Blood glucose was monitored weekly in fed and fasted states to assess glycemic control. While intermittent fasting lowered fasted blood glucose in both groups, no significant body weight or metabolic tissue mass changes were observed. Metabolic cage data demonstrated increased reliance on fat-based substrates for energy in control mice that underwent intermittent fasting during feeding and fasting periods. Diabetic mice did not show significant changes in the fasted state, but intermittent fasting led to increased reliance on carbohydrate oxidation during re-feeding periods, indicating impaired metabolic flexibility. After 10 weeks, the mice were sacrificed, and metabolic tissue histology (adipose, liver, skeletal muscle) will be performed. We will also analyze serum markers (alanine, fatty acids, glycerol, glucose, insulin) and the activity of the metabolic enzyme alanine transaminase (ALT) in the muscle and liver. This experiment will improve our understanding of how lipolysis and protein breakdown in muscle regulate lean mass versus fat mass loss in obesity and T2D, leading to more effective tailoring of fasting to specific populations. Presentation: 6/3/2024

Analysis of fat oxidation capacity during cardiopulmonary exercise testing indicates long-lasting metabolic disturbance in patients with post-covid-19 syndrome

Background & AimsPost-COVID-19 Syndrome (PCS) is characterized by symptoms including fatigue, reduced physical performance, dyspnea, cognitive impairment, and psychological distress. The mechanisms underlying the onset and severity of PCS point to mitochondrial dysfunction as significant contributor. This study examined fat oxidation as a function of mitochondrial capacity during exercise. MethodsSingle-center prospective cohort study during inpatient rehabilitation. Cardiopulmonary exercise testing and assessment of fatigue using questionnaires were performed at admission and discharge. Detailed spirometric breath-by-breath data were used to calculate substrate oxidation rates. ResultsPatients (N=145; 38% women; 49.7±11.4 years) were referred to rehabilitation 253.4±130.6 days after infection. Lead symptoms included fatigue/exercise intolerance (79.9%), shortness of breath (77.0%), and cognitive dysfunction (55.1%). Fat oxidation capacity was disturbed in PCS patients overall (AUC: 11.3[10.7-11.9]) compared to healthy controls (p<0.0001), with hospitalization during acute infection predicting the level of disturbance (p<0.0001). Low exercise capacity and high fatigue scores resulted in reduced fat oxidation (both p<0.0001). In particular, younger males were affected by significantly reduced fat oxidation capacity (sex: p=0.002; age: p<0.001). Metabolic disturbance was significantly improved during exercise-based rehabilitation (AUC: 14.9[14.4-15.4]; p<0.0001), even for the group of younger impaired males (+44.2%; p<0.0001). Carbohydrate oxidation was not impaired. ConclusionsPCS-specific restrictions in fat oxidation may indicate persistent mitochondrial dysfunction. Clinical assessment of PCS patients should include detailed breath-by-breath analysis during exercise to identify metabolic alterations especially in the group of younger males identified in this report. Exercise-based rehabilitation results in improved exercise capacity and fat oxidation and thus likely mitochondrial function. Clinical Trials: NCT06468722

Humidity Increases Carbohydrate Oxidation In Females During Walking Under Load Carriage In A Hot Environment

Humidity Increases Carbohydrate Oxidation In Females During Walking Under Load Carriage In A Hot Environment

Effect of weight-maintaining ketogenic diet on glycemic control and insulin sensitivity in obese T2D subjects

IntroductionLow carbohydrate ketogenic diets have received renewed interest for the treatment of obesity and type 2 diabetes. These diets promote weight loss, improve glycemic control, and reduce insulin resistance. However,...

Ru/MgO-catalysed selective aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

Biomass valorisation through the selective oxidation of carbohydrate and lipid derivatives offers access to an array of platform chemicals through energy- and atom-efficient catalytic processes. Supported metal nanoparticles are promising catalysts for the aerobic selective oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA), but typically require strong liquid base to achieve high selectivity. Here, we explore the utility of MgO as a solid base support for the Ru-catalysed aerobic oxidation of HMF, obtaining 68% FDCA yield at 160°C and 1.5 MPa of O2 using &lt;1 mol-% metal.

Moderately cool environment with rain and wind increases cold strain and energy expenditure via carbohydrate oxidation during running exercise.

Outdoor exercise often proceeds despite rain and wind in cool conditions. The aim of this study was to investigate the effects of rain with wind on physiological responses during running exercise at 70% V̇O<inf>2max</inf> in cool conditions. Eleven healthy men exercised on a treadmill at 70% V̇O<inf>2max</inf> intensity for 60 min under conditions of 10 mm/h rain and 3 m/sec wind (RW) or not (CON) at 10°C in a climatic chamber able to simulate various temperature, humidity, rain, and wind conditions. Body temperature, expired air, and blood samples were measured at rest and exercise. Rectal temperature, mean weighted skin temperature, and thermal sensation were all significantly lower in RW than in CON during exercise (all P<0.05). Oxygen uptake was significantly higher in RW than in CON during exercise (all P<0.05). Participants' rating of perceived exertion was significantly higher in RW than in CON at 50 and 60 min (P<0.05). Respiratory exchange ratio was significantly higher in RW than in CON at 10, 20, and 40 min. Plasma lactate concentration and plasma norepinephrine levels were significantly higher in RW than in CON during exercise (both P<0.05). Rain with wind intensified body heat loss, and energy expenditure and carbohydrate oxidation increased as the body cooled. These conditions may decrease exercise performance.

No effect of circulating leptin on energy metabolism in normal weight or overweight/obese lactating mothers: The case-control Breastmilk and the Link to Overweight/Obesity and Maternal diet (BLOOM) study

Pregnancy and lactation are associated with metabolic changes, including alterations in energy metabolism, which are closely linked to body mass and composition due to hormonal status. Therefore, the objective of this study was to investigate the energy metabolism in exclusively or predominantly breastfeeding mothers with normal weight (NW) and overweight/obesity (OW/OB) and evaluate its associations with fasting serum leptin. This cross-sectional BLOOM study was conducted among 39 mothers (n=19 NW, n=20 OW/OB) in 15.5±1.2 weeks of lactation. The leptin was analyzed in a blood sample using an enzyme-linked immunosorbent assay, body composition was analyzed by dual-energy X-ray absorptiometry, and resting metabolic rate (RMR) was measured by indirect calorimetry method. The average RMR for all groups was 1747.5±281.9kcal/d, with a statistically significant difference between groups (1932.7±222.6 vs. 1550.5±190.6, p<0.001, respectively in the OW/OB and NW group). The OW/OB mothers had higher oxygen uptake (VO2) and exhaled carbon dioxide (VCO2), but not respiratory quotient (RQ), carbohydrate (CHO%) and lipid oxidation (FAT%). When analyzing correlations stratified by BMI category, we found that serum leptin was correlated with CHO% negatively, and with FAT% positively in the NW but not in OW/OB mothers. Additionally, serum leptin was a significant predictor of RMR, VCO2, VO2, CHO%, and RMR/kg of total body weight. However, after adjusting for confounders, the observed associations were no longer statistically significant (RMR: β=0.113, 95% CI-0.354-0.319; VO2: β=0.141, 95% CI-0.462-0.744; VCO2: β=0.238, 95% CI-0.411-0.888; CHO%: β=-0.146, 95% CI-0.151-0.444; RMR/kg of total body weight: β=-0.294, 95% CI-0.831-0.244). Our results did not support the hypothesis that leptin plays a role in regulating energy homeostasis during lactation.

Production of Citric Acid from Different Aspergillus species Obtained from Soil

The genus Aspergillus is considered highly important in the production of various types of enzymes and organic acids. Aspergillus species produce organic acids such as citric acid, itaconic acid, and malic acid, which are one of the most important alternate techniques for chemical processes. Citric acid is an essential primary agricultural product that is extensively used in the world. It acts as an intermediate in the tricarboxylic acid cycle (citric acid cycle) during the oxidation of carbohydrates to carbon dioxide. Citric acid has an important role in industries involving the production of food products, beverages, pharmaceutical and agricultural products, detergents, and cosmetics. The production of citric acid, a crucial agricultural commodity with widespread applications in various industries including food, beverages, pharmaceuticals, agriculture, detergents, and cosmetics, heavily relies on microbial fermentation. The great demand for citric acid due to its wide industrial applications and less toxicity. Citric acid can be produced using less expensive substrates that are renewable too. In this work, Aspergillus species was isolated from the soil source, collected in different localities of Chhatrapati Sambhajinagar. The total 90 different isolates are isolated among these the 20 different Aspergillus species are isolated and pure culture by using potato dextrose agar (PDA) Czapek dox agar medium and study the effect of different media on growth and sporulation of different Aspergillus species and the quantitative analysis of citric acid production was done by titration method with help of NaOH and phenolphthalein indicator. The main reason for the study increases is the large number of applications that can be found for citric acid, primarily in the food and pharmaceutical industries

Intermittent fasting increases fat oxidation and promotes metabolic flexibility in lean mice but not obese type 2 diabetic mice.

Obesity and type 2 diabetes (T2D) are associated with metabolic inflexibility, characterized by an impaired ability to switch between substrate storage and utilization pathways. Metabolic inflexibility during obesity is typified by lower engagement of fatty acid metabolism despite an ample supply of stored lipids. Intermittent fasting (IF) can promote metabolic flexibility. However, it is not clear how obesity and T2D alter metabolic flexibility after repeated IF. Male obese db/db and control db/+ mice were fasted for 24 h twice a week for 10 wk. This 5:2 IF regimen did not alter body mass, body composition, food intake, or physical activity in db/db or db/+ mice. After IF, db/db mice had lower fatty acid oxidation and higher carbohydrate oxidation in the fed state, indicating metabolic inflexibility to metabolize lipids. After IF, control db/+ mice had higher fatty acid oxidation and lower carbohydrate oxidation in the fed state, characteristic of metabolic flexibility, and increased engagement of lipid metabolism. In the fasted state, IF lowered carbohydrate oxidation and increased fatty acid oxidation in control db/+ mice but not in obese db/db mice. After IF, db/db mice also had lower serum β-hydroxybutyrate than control db/+ mice. Ten weeks of IF decreased adipocyte size in visceral adipose tissue of control db/+ mice, but this IF regimen did not change adipocyte size in obese db/db mice. Therefore, IF increases fatty acid oxidation and metabolic flexibility in lean mice, but this adaptation is absent in a mouse model of obesity and type 2 diabetes.NEW & NOTEWORTHY We show that a 5:2 intermittent fasting regimen can increase lipid oxidation without altering body mass in lean mice. Therefore, repeated intermittent fasting can increase metabolic flexibility without the need for (or prior to) weight loss. Intermittent fasting did not increase lipid oxidation in mice with obesity and type 2 diabetes, highlighting that obesity and/or type 2 diabetes limit changes in metabolic flexibility and mitigate increased fatty acid oxidation without weight loss during intermittent fasting.

Beneficial Physiological and Metabolic Effects with Acute Intake of New Zealand Blackcurrant Extract during 4 h of Indoor Cycling in a Male Ironman Athlete: A Case Study.

New Zealand blackcurrant (NZBC) is known to alter exercise-induced physiological and metabolic responses with chronic (i.e., 7 days) dosing. We examined the effects of acute intake of New Zealand blackcurrant (NZBC) extract on 4 h indoor cycling-induced physiological and metabolic responses in a male amateur Ironman athlete (age: 49 years; BMI: 24.3 kg·m-2; V˙O2max: 58.6 mL·kg-1·min-1; maximal aerobic power: 400 W; history: 14 Ironman events in 16 years) three weeks before competition. Indirect calorimetry was used and heart rate was recorded at 30 min intervals during 4 h indoor (~22.4 °C, relative humidity: ~55%) constant power (165 W) cycling on a Trek Bontrager connected to a Kickr smart trainer. Blood lactate and rating of perceived exertion (RPE) were taken at 60 min intervals. Study was a single-blind placebo-controlled study with capsules (4 × 105 mg anthocyanins) taken 2 h before starting the 4 h of cycling. Water was allowed ad libitum with personalised consumption of gels [a total of eight with three with caffeine (100 mg)], two bananas and 8 × electrolyte capsules (each 250 mg sodium and 125 mg potassium) at personalised time-points. With NZBC extract (CurraNZ), during 4 h of cycling (mean of 8 measurements), minute ventilation was 8% lower than placebo. In addition, there was no difference for oxygen uptake, with carbon dioxide production found to be 4% lower with NZBC extract. With the NZBC extract, the ventilatory equivalents were lower for oxygen and carbon dioxide by 5.5% and 3.7%; heart rate was lower by 10 beats·min-1; lactate was 40% different with lower lactate at 2, 3 and 4 h; RPE was lower at 2, 3 and 4 h; and carbohydrate oxidation was 11% lower. With NZBC extract, there was a trend for fat oxidation to be higher by 13% (p = 0.096), with the respiratory exchange ratio being lower by 0.02 units. Acute intake of New Zealand blackcurrant extract (420 mg anthocyanins) provided beneficial physiological and metabolic responses during 4 h of indoor constant power cycling in a male amateur Ironman athlete 3 weeks before a competition. Future work is required to address whether acute and chronic dosing strategies with New Zealand blackcurrant provide a nutritional ergogenic effect for Ironman athletes to enhance swimming, cycling and running performance.

The effect of tart cherry juice compared to a sports drink on cycling exercise performance, substrate metabolism, and recovery.

Tart cherries have low glycemic index, antioxidant and anti-inflammatory properties, and therefore may benefit performance and recovery from exercise. We determined the effects of consuming tart cherry juice versus a high-glycemic index sports drink on cycling performance, substrate oxidation, and recovery of low-frequency fatigue. Using a randomized, counter-balanced cross-over design, with one-month washout, 12 recreational cyclists (8 males and 4 females; 35±16y; VO2peak 38.2±7.4 ml/kg/min) consumed cherry juice or sports drink twice a day (300mL/d) for 4d before and 2d after exercise. On the exercise day, beverages (providing 1g/kg carbohydrate) were consumed 45min before 90min of cycling at 65%VO2peak, followed by a 10km time trial. Blood glucose, lactate, carbohydrate and fat oxidation, respiratory exchange ratio (RER), O2 cost of cycling, and rating of perceived exertion (RPE) were measured during the initial 90min of cycling. Muscle soreness, maximal voluntary contraction (MVC) and low-frequency fatigue were determined at baseline and after the time trial on the exercise day, and 30min after beverage consumption 24 and 48h later. There were no differences for time trial performance (17±3min cherry juice vs. 17±2min sports drink, p = 0.27) or any other measures between drink conditions. There were time main effects (p<0.05) for isometric MVC (decreasing) and low-frequency fatigue (increasing; i.e. decreased force at low relative to high stimulation frequencies), changing significantly from baseline to post-exercise and then returning to baseline at 24h post-exercise. Tart cherry juice was not effective for improving performance, substrate oxidation during exercise, and recovery from exercise, compared to a high-glycemic index sports drink.

Metabolomic and Transcriptomic Analysis of Unique Floral Coloration in Osmanthus fragrans Cultivars

The floral color phenotypes of Osmanthus fragrans cultivars range from light yellow to orange yellow, with ‘Yanzhi Hong’ being the only reported cultivar with a red color. However, the underlying reason for this unique floral coloration remains unclear. The study conducted targeted metabolomics and transcriptomics analyses on the petals of ‘Yanzhi Hong’ at both initial and peak flowering stages. Candidate gene expression was validated, and expression levels of the petals of three cultivars were compared using RT-qPCR. The results revealed the presence of 27 components in the petals of ‘Yanzhi Hong’, including 5 carotenoids, 8 xanthophylls, and 14 xanthophyll esters. Notably, lycopene was detected in abundance for the first time in O. fragrans cultivars. Carotenes accounted for 78.82 ± 3.17% and 91.19 ± 1.69% of the total carotenoid content in petals during the initial and peak flowering stages, respectively, with all carotene contents increasing during the peak flowering period. β-carotene, lycopene, and γ-carotene were identified as the top three carotene components in petals during both initial and full flowering stages. The unique blush red color of ‘Yanzhi Hong’ petals could be attributed to the low content of α-carotene and the rich accumulation of lycopene. Furthermore, a total of 1550 differentially expressed genes (DEGs) were identified in petals at the peak flowering stage relative to the initial flowering stage, with 1003 genes being downregulated and 547 genes being upregulated during the full flowering stage. There are 926 differentially expressed genes (DEGs) annotated in the Gene Ontology (GO) database. Among these DEGs, those that were downregulated and upregulated during the peak flowering period showed significant enrichment in carbohydrate metabolism and oxidation–reduction processes, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis identified 14 structural genes associated with phenylpropanoid biosynthesis and 7 structural genes linked to carotenoid biosynthesis. Expression levels of candidate genes involved in carotenoid biosynthesis were examined in the petals of three cultivars (‘Yanzhi Hong’, ‘Liuye Jingui’, and ‘Gecheng Dangui’) at both the initial and peak flowering stages. The results indicated that the decreased expression of LYG009054 (LYCE) and LYG018651 (LYCB) in ‘Yanzhi Hong’ resulted in higher lycopene accumulation and lower α-carotene content in the petals. This study offers valuable insights into the mechanisms underlying the unique flower color phenotype of O. fragrans, proving a basis for further research on carotenoid metabolism pathways and the breeding of new cultivars with a variety of flower colors in O. fragrans.

Regulation of muscle pyruvate dehydrogenase activity and fuel use during exercise in high-altitude deer mice.

Adult, lab-reared, highland deer mice acclimate to hypoxia by increasing reliance on carbohydrates to fuel exercise. Yet neither the underlying mechanisms for this shift in fuel use nor the impact of lifetime hypoxia exposure experienced in high alpine conditions, are fully understood. Thus, we assessed the use of fuel during exercise in wild highland deer mice running in their native environment. We examined a key step in muscle carbohydrate oxidation - the regulation of pyruvate dehydrogenase (PDH) - during exercise at altitude in wild highlanders and in first generation (G1) lab-born and -raised highlanders acclimated to normoxia or hypoxia. PDH activity was also determined in the gastrocnemius of G1 highlanders using an in situ muscle preparation. We found that wild highlanders had a high reliance on carbohydrates while running in their native environment, consistent with data from hypoxia-acclimated G1 highlanders. PDH activity in the gastrocnemius was similar post exercise between G1 and wild highlanders. However, when the gastrocnemius was stimulated at a light work rate in situ, PDH activity was higher in hypoxia-acclimated G1 highlanders and was associated with lower intramuscular lactate levels. These findings were supported by lower PDH kinase 2 protein production in hypoxia-acclimated G1 mice. Our findings indicate that adult phenotypic plasticity in response to low oxygen is sufficient to increase carbohydrate reliance during exercise in highland deer mice. Additionally, variation in PDH regulation with hypoxia acclimation contributes to shifts in whole-animal patterns of fuel use and is likely to improve exercise performance via elevated energy yield per mole of O2. .

Metabolic flexibility and resting autonomic function in active menopausal women.

The present study aims to analyze the relationship between cardiac autonomic control at rest-i.e., baseline Heart Rate Variability (HRV)-and metabolic flexibility assessed by means of the FATox and CHOox oxidation rates at the intensities of maximum fat and carbohydrate oxidation (MFO and MCO, respectively). Twenty-four active over-60 women (66.8 ± 4.4years) had their HRV assessed with 10min recordings under resting conditions, and this was analyzed with Kubios Scientific software. After this, an incremental submaximal cycling test, starting at 30watts, with increments of 10watts every 3min 15s was performed. FATox and CHOox were calculated in the last 60s at each step, using Frayn's equation. MFO and MCO were further obtained. Nonlinear SampEn and 1-DFAα1 (Detrending Fluctuation Analysis score) at rest were both moderate and significantly (p < 0.05) related to FATox (r = 0.43, r = -0.40) and CHOox (r = -0.59, r = 0.41), as well as RER (r = -0.43, r = 0.43) at FATmax intensity. At the MCO intensity, no association was observed between HRV and oxidation rates. However, DFAα1 (r = -0.63, p < 0.05), the frequency ratio LF/HF (r = -0.63, p < 0.05), and the Poincaré ratio SD1/SD2 (r = 0.48, p < 0.05) were correlated with blood lactate concentration. These results support the autonomic resources hypothesis, suggesting that better autonomic function at rest is related to enhanced metabolic flexibility in postmenopausal women. They also underpin a comprehensive analysis of cardiovascular-autonomic health with aging. The results imply that non-linear DFAα1 and SampEn are appropriate to analyze this association in health of the aging cardiovascular-autonomic system.

Pleiotropic effects of an eQTL in the CELSR2/PSRC1/SORT1 cluster that associates with LDL-C and resting metabolic rate.

The locus CELSR2-PSRC1-SORT1, a primary genetic signal for lipids, has recently been implicated in different metabolic processes. Our investigation identified its association with energy metabolism. To determine biological mechanisms that govern diverse functions of this locus. Genotypes for 491,265 variants in 7,000 clinically characterized American Indians were previously determined using a custom-designed array specific for this longitudinally studied American Indian population. Among the genotyped individuals, 5,205 had measures of fasting lipid levels and 509 had measures of resting metabolic rate (RMR) and substrate oxidation rate assessed through indirect calorimetry. A genome-wide association study (GWAS) for LDL-C levels identified a variant in CELSR2 and the molecular impact of this variant on gene expression was assessed in skeletal muscle biopsies from 207 participants, followed by functional validation in mouse myoblasts using a luciferase assay. A GWAS in American Indians identified rs12740374 in CELSR2 as the top signal for LDL-C levels (P = 1 × 10-22); further analysis of this variant identified an unexpected correlation with reduced RMR (effect = -44.3 kcal/day/minor-allele) and carbohydrate oxidation rate (effect = -5.21 mg/hour/kg-EMBS). Tagged variants showed a distinct linkage disequilibrium architecture in American Indians, highlighting a potential functional variant, rs6670347 (minor-allele frequency = 0.20). Positioned in the glucocorticoid receptor's core binding motif, rs6670347 is part of a skeletal muscle-specific enhancer. Human skeletal muscle transcriptome analysis showed CELSR2 as the most differentially expressed gene (P = 1.9 × 10-7), with the RMR-lowering minor allele elevating gene expression. Experiments in mouse myoblasts confirmed enhancer-based regulation of CELSR2 expression, dependent on glucocorticoids. Rs6670347 also associated with increased oxidative phosphorylation gene expression; CELSR2 as a regulator of these genes, suggests potential influence on energy metabolism through muscle oxidative capacity. Variants in the CELSR2/PSRC1/SORT1 locus exhibit tissue-specific effects on metabolic traits, with an independent role in muscle metabolism through glucocorticoid signaling.