Development of a tamarind-based functional beverage with partially-hydrolyzed agave syrup and the health effects of its consumption in C57BL/6 mice

Excess consumption of sweetened beverages is associated with a global rise in metabolic diseases. Tamarind and partially-hydrolyzed agave syrup have potential for developing healthier beverages. Our objective was to develop a functional beverage using these ingredients (PH-AS-B). We also evaluate shelf-life stability (physicochemical, microbiological, and antioxidant properties) and health effects in C57BL/6 mice compared with tamarind beverages sweetened with glucose or fructose. Optimal tamarind extraction conditions were a 1:10 ratio (g pulp/mL water) and boiling for 30 min, and the resulting beverage had a shelf life of two months at 4 °C. Non-volatile metabolites were identified using HPLC/MS. PH-AS-B was associated with decreased blood cholesterol (5%) and triglyceride (20-35%) concentrations in healthy mice as well as lower lipid (82%) concentrations and evidence of protein oxidation (42%) in the liver, compared with glucose- and fructose-sweetened tamarind beverages. In conclusion, PH-AS-B was stable and associated with beneficial metabolic properties in healthy mice.

6-Gingerol alleviates ectopic lipid deposition in skeletal muscle by regulating CD36 translocation and mitochondrial function

Ectopic lipid deposition (ELD) and mitochondrial dysfunction are common causes of metabolic disorders in humans. Consuming too much fructose can result in mitochondrial dysfunction and metabolic disorders. 6-Gingerol, the main component of ginger (Zingiber officinale Roscoe), has been proven to alleviate metabolic disorders. This study seeks to examine the effects of 6-gingerol on metabolic disorders caused by fructose and uncover the underlying molecular mechanisms. In this study, the results showed that 6-Gingerol ameliorated high-fructose-induced metabolic disorders. Moreover, it inhibited CD36 membrane translocation, increased CD36 expression in the mitochondria, and decreased the O-GlcNAc modification of CD36 and OGT expression in vitro and vivo. In addition, 6-Gingerol enhanced the performance of mitochondria in the skeletal muscle and boosted the respiratory capability of L6 myotubes. This study provides a theoretical basis and new insights for the development of lipid-lowering drugs in clinical practice.

Economical one-pot synthesis of isoquercetin and D-allulose from quercetin and sucrose using whole-cell biocatalyst

Isoquercetin and D-allulose have diverse applications and significant value in antioxidant, antibacterial, antiviral, and lipid metabolism. Isoquercetin can be synthesized from quercetin, while D-allulose is converted from D-fructose. However, their production scale and overall quality are relatively low, leading to high production costs. In this study, we have devised a cost-effective one-pot method for biosynthesizing isoquercetin and D-allulose using a whole-cell biocatalyst derived from quercetin and sucrose. To achieve this, the optimized isoquercetin synthase and D-allulose-3-epimerase were initially identified through isofunctional gene screening. In order to reduce the cost of uridine diphosphate glucose (UDPG) during isoquercetin synthesis and ensure a continuous supply of UDPG, sucrose synthase is introduced to enable the self-circulation of UDPG. At the same time, the inclusion of sucrose permease was utilized to successfully facilitate the catalytic production of D-allulose in whole cells. Finally, the recombinant strain BL21/UGT-SUS+DAE-SUP, which overexpresses MiF3GTMUT, GmSUS, EcSUP, and DAEase, was obtained. This strain co-produced 41±2.4 mg/L of isoquercetin and 5.7±0.8 g/L of D-allulose using 120 mg/L of quercetin and 20 g/L of sucrose as substrates for 5 h after optimization. This is the first green synthesis method that can simultaneously produce flavonoid compounds and rare sugars. These findings provide valuable insights and potential for future industrial production, as well as practical applications in factories.

Fructose malabsorption and fructan malabsorption are associated in patients with irritable bowel syndrome

BACKGROUND

Food malabsorption and intolerance is implicated in gastrointestinal symptoms among patients with irritable bowel syndrome (IBS). Key triggers include fructose and fructan. Prior studies examined fructose and fructan malabsorption separately in IBS patients. None have concurrently assessed both within the same patient group. We aimed to investigate the association between fructose and fructan malabsorption in the same patients with IBS using hydrogen breath testing (HBT).

METHODS

We retrospectively identified patients with IBS who underwent fructose and fructan HBTs and abstracted their results from the electronic medical record. Fructose and fructan HBTs were performed by administering a 25 g fructose solution or 10 g fructan solution, followed by breath hydrogen readings every 30 min for 3 h. Patients were positive for fructose or fructan malabsorption if breath hydrogen levels exceeded 20 ppm.

RESULTS

Of 186 IBS patients, 71 (38.2%) were positive for fructose malabsorption and 91 (48.9%) were positive for fructan malabsorption. Of these patients, 42 (22.6%) were positive for fructose malabsorption and fructan malabsorption. Positive fructose HBT readings were significantly associated with positive fructan HBT readings (p = 0.0283). Patients positive for fructose malabsorption or fructan malabsorption had 1.951 times higher odds of testing positive for the other carbohydrate.

CONCLUSIONS

Our results reveal a clinically significant association between fructose malabsorption and fructan malabsorption in patients with IBS. Fructan malabsorption should be assessed in patients with fructose malabsorption, and vice versa. Further studies are required to identify the mechanisms underlying our findings.

Fructose Potentiates Bone Loss and Marrow Adipose Tissue Accumulation by Inhibiting Adenosine 5'-Monophosphate-Activated Protein Kinase in Mesenchymal Stem Cells

Increased fructose consumption has been elucidated to contribute to metabolic diseases. Bone is a dynamic organ that undergoes constant remodeling. However, the effects of fructose on bone health are still in dispute. Here, we identified fructose deteriorated bone mineral density while promoting the abundance of bone marrow adipose tissue. Fructose remarkably promoted the bone marrow mesenchymal stem cells' (BMMSCs) adipogenic commitment at the expense of osteogenic commitment. Fructose boosted the glycolysis of BMMSCs and inhibited phosphorylation of adenosine 5'-monophosphate-activated protein kinase (AMPK), which played a crucial role in bone-fat alteration. Our results suggested that fructose potentiated bone loss and marrow adipose tissue accumulation by suppressing AMPK activation in BMMSCs. Understanding fructose which affected bone metabolism was thus of primary importance in order to establish preventative measures or treatments for this condition.

Enhancement of the d-Allulose 3-Epimerase Expression in Bacillus subtilis through Both Transcriptional and Translational Regulations

d-Allulose, a functional bulk sweetener, has recently attracted increasing attention because of its low-caloric-ness properties and diverse health effects. d-Allulose is industrially produced by the enzymatic epimerization of d-fructose, which is catalyzed by ketose 3-epimerase (KEase). In this study, the food-grade expression of KEase was studied using Bacillus subtills as the host. Clostridium sp. d-allulose 3-epimerase (Clsp-DAEase) was screened from nine d-allulose-producing KEases, showing better potential for expression in B. subtills WB600. Promoter-based transcriptional regulation and N-terminal coding sequence (NCS)-based translational regulation were studied to enhance the DAEase expression level. In addition, the synergistic effect of promoter and NCS on the Clsp-DAEase expression was studied. Finally, the strain with the combination of a PHapII promoter and gln A-Up NCS was selected as the best Clsp-DAEase-producing strain. It efficiently produced Clsp-DAEase with a total activity of 333.2 and 1860.6 U/mL by shake-flask and fed-batch cultivations, respectively.

Fructose dose-dependently influences colon barrier function by regulation of some main physical, immune, and biological factors in rats

Little is known about the effects of fructose on colonic function. Here, forty-eight 7-week-old male SD rats were randomly divided into four groups and given 0, 7.5%, 12.75%, and 35% fructose in diet for 8 weeks respectively to investigate the regulatory influence of fructose on colonic barrier function. The exact amount of fructose intake was tracked and recorded. We showed that fructose affects colonic barrier function in a dose-dependent manner. High-fructose at a dose of 1.69±0.23 g/kg/day could damage the physical barrier function of the colon by down-regulating expression of tight junction proteins (ZO-1 and occludin) and mucus layer biomarkers (MUC2 and TFF3). High fructose reduced sIgA and the anti-inflammatory cytokine (IL-10), induced abdominal fat accumulation and pro-inflammatory cytokines (IL-6 and IL-8), leading to colon inflammation and immune barrier dysfunction. In addition, high-fructose altered the biological barrier of the colon by decreasing the abundance of Blautia, Ruminococcus, and Lactobacillius, and increasing the abundance of Allobaculum at the genus level, leading to a reduction in short-chain fatty acids (SCFAs), amino acids, and carbohydrates, etc. Low fructose at a dose of 0.31±0.05 g/kg/day showed no adverse effects on the colonic barrier. The ability of fructose to affect the colonic barrier through physical, immune, and biological pathways provides additional insight into the intestinal disorders caused by high-fructose diets.

Growth-Coupled Evolutionary Pressure Improving Epimerases for D-Allulose Biosynthesis Using a Biosensor-Assisted In Vivo Selection Platform

Fast screening strategies that enable high-throughput evaluation and identification of desired variants from diversified enzyme libraries are crucial to tailoring biocatalysts for the synthesis of D-allulose, which is currently limited by the poor catalytic performance of ketose 3-epimerases (KEases). Here, the study designs a minimally equipment-dependent, high-throughput, and growth-coupled in vivo screening platform founded on a redesigned D-allulose-dependent biosensor system. The genetic elements modulating regulator PsiR expression levels undergo systematic optimization to improve the growth-responsive dynamic range of the biosensor, which presents ≈30-fold facilitated growth optical density with a high signal-to-noise ratio (1.52 to 0.05) toward D-allulose concentrations from 0 to 100 mm. Structural analysis and evolutionary conservation analysis of Agrobacterium sp. SUL3 D-allulose 3-epimerase (ADAE) reveal a highly conserved catalytic active site and variable hydrophobic pocket, which together regulate substrate recognition. Structure-guided rational design and directed evolution are implemented using the growth-coupled in vivo screening platform to reprogram ADAE, in which a mutant M42 (P38N/V102A/Y201L/S207N/I251R) is identified with a 6.28-fold enhancement of catalytic activity and significantly improved thermostability with a 2.5-fold increase of the half-life at 60 °C. The research demonstrates that biosensor-assisted growth-coupled evolutionary pressure combined with structure-guided rational design provides a universal route for engineering KEases.

Liver ChREBP deficiency inhibits fructose-induced insulin resistance in pregnant mice and female offspring

High fructose intake during pregnancy increases insulin resistance (IR) and gestational diabetes mellitus (GDM) risk. IR during pregnancy primarily results from elevated hormone levels. We aim to determine the role of liver carbohydrate response element binding protein (ChREBP) in insulin sensitivity and lipid metabolism in pregnant mice and their offspring. Pregnant C57BL/6J wild-type mice and hepatocyte-specific ChREBP-deficient mice were fed with a high-fructose diet (HFrD) or normal chow diet (NC) pre-delivery. We found that the combination of HFrD with pregnancy excessively activates hepatic ChREBP, stimulating progesterone synthesis by increasing MTTP expression, which exacerbates IR. Increased progesterone levels upregulated hepatic ChREBP via the progesterone-PPARγ axis. Placental progesterone activated the progesterone-ChREBP loop in female offspring, contributing to IR and lipid accumulation. In normal dietary conditions, hepatic ChREBP modestly affected progesterone production and influenced IR during pregnancy. Our findings reveal the role of hepatic ChREBP in regulating insulin sensitivity and lipid homeostasis in both pregnant mice consuming an HFrD and female offspring, and suggest it as a potential target for managing gestational metabolic disorders, including GDM.

The temporal-spatial expression and functional analysis of three gustatory receptor genes in Solenopsis invicta using sweet and bitter compounds

The insect gustatory system participates in identifying potential food sources and avoiding toxic compounds. During this process, gustatory receptors (GRs) recognize feeding stimulant and deterrent compounds. However, the GRs involved in recognizing stimulant and deterrent compounds in the red imported fire ant, Solenopsis invicta, remain unknown. Therefore, we conducted a study on the genes SinvGR1, SinvGR32b, and SinvGR28a to investigate the roles of GRs in detecting feeding stimulant and deterrent compounds. In this current study, we found that sucrose and fructose are feeding stimulants and the bitter compound quinine is a feeding deterrent. The fire ant workers showed significant behavior changes to avoid the bitter taste in feeding stimulant compounds. Reverse transcription quantitative real-time polymerase chain reaction results from developmental stages showed that the SinvGR1, SinvGR32b, and SinvGR28a genes were highly expressed in fire ant workers. Tissue-specific expression profiles indicated that SinvGR1, SinvGR32b, and SinvGR28a were specifically expressed in the antennae and foreleg tarsi of workers, whereas SinvGR32b gene transcripts were also highly accumulated in the male antennae. Furthermore, the silencing of SinvGR1 or SinvGR32b alone and the co-silencing of both genes disrupted worker stimulation and feeding on sucrose and fructose. The results also showed that SinvGR28a is required for avoiding quinine, as workers with knockdown of the SinvGR28a gene failed to avoid and fed on quinine. This study first identified stimulant and deterrent compounds of fire ant workers and then the GRs involved in the taste recognition of these compounds. This study could provide potential target gustatory genes for the control of the fire ant.

A multi-modal approach to investigate Desmodium gangeticum's influence on stress-induced male infertility: In vivo, in vitro, and in silico assessments

Physical and psychological stress has an inverse relation with male libido and sperm quality. The present study investigates the potential fertility-enhancing properties of Desmodium gangeticum (DG) root extracts in male Wister rats subjected to immobilization-induced stress (SIMB). DG roots were extracted using n-hexane (HEDG), chloroform (CEDG), and water (AEDG). In the pilot study, aphrodisiac protentional was investigated at two doses (125 and 250 mg kg-1) of each extract. In the main study, the HEDG and AEDG at 125 and 250 mg kg-1 were challenged for the stress by immobilization (SIMB), for 6 h daily over 28 days. Parameters assessed included aphrodisiac effects, gonadosomatic index (GSI), semen quality, sperm quantity, fructose content, serum hormonal levels, testicular oxidative stress, and testicular histopathology. Additional in silico studies, including the lipid solubility index, molecular docking, molecular dynamics, and SymMap studies were conducted for validation. HEDG demonstrated significant aphrodisiac activity, improved - GSI, sperm quality and quantity, and fructose content, serum testosterone levels, histological changes induced by SIMB in the testes. Swiss ADME studies indicated Gangetin (a pterocarpan) had a high brain permeation index (4.81), a superior docking score (-8.22), and higher glide energy (-42.60), compared with tadalafil (-7.17). The 'Lig fit Prot' plot in molecular dynamics simulations revealed a strong alignment between Gangetin and phosphodiesterase type 5 (PDE5). HEDG exerts aphrodisiac effects by increasing blood testosterone levels and affecting PDE5 activity. The protective effects on spermatozoa-related parameters and testicular histological changes are attributed to the antioxidant and anti-inflammatory properties, of pterocarpan (gangetin).

Understanding the role of the fructose-1,6-bisphosphatase gene for enhancing the photosynthetic rate in Arabidopsis thaliana

Transgenic Arabidopsis thaliana (ecotype Columbia) was successfully transformed with the gene fructose-1,6-bisphosphatase (FBPas e) and named as AtFBPase plants. Transgenic plants exhibited stable transformation, integration and significantly higher expressions for the transformed gene. Morphological evaluation of transgenic plants showed increased plant height (35cm), number of leaves (25), chlorophyll contents (28%), water use efficiency (increased from 1.5 to 2.6μmol CO2 μmol-1 H2 O) and stomatal conductance (20%), which all resulted in an enhanced photosynthetic rate (2.7μmolm-2 s-1 ) compared to wild type plants. This study suggests the vital role of FBPase gene in the modification of regulatory pathways to enhance the photosynthetic rate, which can also be utilised for economic crops in future.

Enhancing enzyme immobilization: Fabrication of biosilica-based organic-inorganic composite carriers for efficient covalent binding of D-allulose 3-epimerase

D-allulose, an ideal low-calorie sweetener, is primarily produced through the isomerization of d-fructose using D-allulose 3-epimerase (DAE; EC 5.1.3.30). Addressing the gap in available immobilized DAE enzymes for scalable commercial D-allulose production, three core-shell structured organic-inorganic composite silica-based carriers were designed for efficient covalent immobilization of DAE. Natural inorganic diatomite was used as the core, while 3-aminopropyltriethoxysilane (APTES), polyethyleneimine (PEI), and chitosan organic layers were coated as the shells, respectively. These tailored carriers successfully formed robust covalent bonds with DAE enzyme conjugates, cross-linked via glutaraldehyde, and demonstrated enzyme activities of 372 U/g, 1198 U/g, and 381 U/g, respectively. These immobilized enzymes exhibited an expanded pH tolerance and improved thermal stability compared to free DAE. Particularly, the modified diatomite with PEI exhibited a higher density of binding sites than the other carriers and the PEI-coated immobilized DAE enzyme retained 70.4 % of its relative enzyme activity after ten cycles of reuse. This study provides a promising method for DAE immobilization, underscoring the potential of using biosilica-based organic-inorganic composite carriers for the development of robust enzyme systems, thereby advancing the production of value-added food ingredients like D-allulose.

Fructose overconsumption-induced reprogramming of microglia metabolism and function

The overconsumption of dietary fructose has been proposed as a major culprit for the rise of many metabolic diseases in recent years, yet the relationship between a high fructose diet and neurological dysfunction remains to be explored. Although fructose metabolism mainly takes place in the liver and intestine, recent studies have shown that a hyperglycemic condition could induce fructose metabolism in the brain. Notably, microglia, which are tissue-resident macrophages (Mφs) that confer innate immunity in the brain, also express fructose transporters (GLUT5) and are capable of utilizing fructose as a carbon fuel. Together, these studies suggest the possibility that a high fructose diet can regulate the activation and inflammatory response of microglia by metabolic reprogramming, thereby altering the susceptibility of developing neurological dysfunction. In this review, the recent advances in the understanding of microglia metabolism and how it supports its functions will be summarized. The results from both in vivo and in vitro studies that have investigated the mechanistic link between fructose-induced metabolic reprogramming of microglia and its function will then be reviewed. Finally, areas of controversies and their associated implications, as well as directions that warrant future research will be highlighted.

Inflammatory response in dairy cows caused by heat stress and biological mechanisms for maintaining homeostasis

Climate change increases global temperatures, which is lethal to both livestock and humans. Heat stress is known as one of the various livestock stresses, and dairy cows react sensitively to high-temperature stress. We aimed to better understand the effects of heat stress on the health of dairy cows and observing biological changes. Individual cows were divided into normal (21-22 °C, 50-60% humidity) and high temperature (31-32 °C, 80-95% humidity), respectively, for 7-days. We performed metabolomic and transcriptome analyses of the blood and gut microbiomes of feces. In the high-temperature group, nine metabolites including linoleic acid and fructose were downregulated, and 154 upregulated and 72 downregulated DEGs (Differentially Expressed Genes) were identified, and eighteen microbes including Intestinimonas and Pseudoflavonifractor in genus level were significantly different from normal group. Linoleic acid and fructose have confirmed that associated with various stresses, and functional analysis of DEG and microorganisms showing significant differences confirmed that high-temperature stress is related to the inflammatory response, immune system, cellular energy mechanism, and microbial butyrate production. These biological changes were likely to withstand high-temperature stress. Immune and inflammatory responses are known to be induced by heat stress, which has been identified to maintain homeostasis through modulation at metabolome, transcriptome and microbiome levels. In these findings, heat stress condition can trigger alteration of immune system and cellular energy metabolism, which is shown as reduced metabolites, pathway enrichment and differential microbes. As results of this study did not include direct phenotypic data, we believe that additional validation is required in the future. In conclusion, high-temperature stress contributed to the reduction of metabolites, changes in gene expression patterns and composition of gut microbiota, which are thought to support dairy cows in withstanding high-temperature stress via modulating immune-related genes, and cellular energy metabolism to maintain homeostasis.

Variation of sugar compounds in Phoebe chekiangensis seeds during natural desiccation

To investigate the role of sugar metabolism in desiccation-sensitive seeds, we performed a natural desiccation treatment on Phoebe chekiangensis seeds in a room and systematically analyzed the changes in seed germination, sugar compounds, malondialdehyde, and relative electrical conductivity during the seed desiccation. The results revealed that the initial moisture content of P. chekiangensis seed was very high (37.06%) and the seed was sensitive to desiccation, the germination percentage of the seed decreased to 5.33% when the seed was desiccated to 22.04% of moisture content, therefore, the seeds were considered recalcitrant. Based on the logistic model, we know that the moisture content of the seeds is 29.05% when the germination percentage drops to 50% and that it is desirable to keep the seed moisture content above 31.74% during ambient transportation. During seed desiccation, sucrose and trehalose contents exhibited increasing trends, and raffinose also increased during the late stage of desiccation, however, low levels of the non-reducing sugar accumulations may not prevent the loss of seed viability caused by desiccation. Glucose and fructose predominated among sugar compounds, and they showed a slight increase followed by a significant decrease. Their depletion may have contributed to the accumulation of sucrose and raffinose family oligosaccharides. Correlation analysis revealed a significant relationship between the accumulation of sucrose, trehalose, and soluble sugars, and the reduction in seed viability. Sucrose showed a significant negative correlation with glucose and fructose. Trehalose also exhibited the same pattern of correlation. These results provided additional data and theoretical support for understanding the mechanism of sugar metabolism in seed desiccation sensitivity.

Profiling Cell Heterogeneity and Fructose Transporter Expression in the Rat Nephron by Integrating Single-Cell and Microdissected Tubule Segment Transcriptomes

Single-cell RNA sequencing (scRNAseq) is a crucial tool in kidney research. These technologies cluster cells based on transcriptome similarity, irrespective of the anatomical location and order within the nephron. Thus, a transcriptome cluster may obscure the heterogeneity of the cell population within a nephron segment. Elevated dietary fructose leads to salt-sensitive hypertension, in part, through fructose reabsorption in the proximal tubule (PT). However, the organization of the four known fructose transporters in apical PTs (SGLT4, SGLT5, GLUT5, and NaGLT1) remains poorly understood. We hypothesized that cells within each subsegment of the proximal tubule exhibit complex, heterogeneous fructose transporter expression patterns. To test this hypothesis, we analyzed rat kidney transcriptomes and proteomes from publicly available scRNAseq and tubule microdissection databases. We found that microdissected PT-S1 segments consist of 81% ± 12% cells with scRNAseq-derived transcriptional characteristics of S1, whereas PT-S2 express a mixture of 18% ± 9% S1, 58% ± 8% S2, and 19% ± 5% S3 transcripts, and PT-S3 consists of 75% ± 9% S3 transcripts. The expression of all four fructose transporters was detectable in all three PT segments, but key fructose transporters SGLT5 and GLUT5 progressively increased from S1 to S3, and both were significantly upregulated in S3 vs. S1/S2 (Slc5a10: 1.9 log2FC, p < 1 × 10-299; Scl2a5: 1.4 log2FC, p < 4 × 10-105). A similar distribution was found in human kidneys. These data suggest that S3 is the primary site of fructose reabsorption in both humans and rats. Finally, because of the multiple scRNAseq transcriptional phenotypes found in each segment, our findings also imply that anatomical labels applied to scRNAseq clusters may be misleading.

Biosynthesis of Cytidine Diphosphate-6-d-Glucitol for the Capsular Polysaccharides of Campylobacter jejuni

Campylobacter jejuni is a Gram-negative pathogenic bacterium commonly found in chickens and is the leading cause of human diarrheal disease worldwide. The various serotypes of C. jejuni produce structurally distinct capsular polysaccharides (CPSs) on the exterior surfaces of the cell wall. The capsular polysaccharide from C. jejuni serotype HS:5 is composed of a repeating sequence of d-glycero-d-manno-heptose and d-glucitol-6-phosphate. We previously defined the pathway for the production of d-glycero-d-manno-heptose in C. jejuni. Here, we elucidate the biosynthetic pathway for the assembly of cytidine diphosphate (CDP)-6-d-glucitol by the combined action of two previously uncharacterized enzymes. The first enzyme catalyzes the formation of CDP-6-d-fructose from cytidine triphosphate (CTP) and d-fructose-6-phosphate. The second enzyme reduces CDP-6-d-fructose with NADPH to generate CDP-6-d-glucitol. Using sequence similarity network (SSN) and genome neighborhood network (GNN) analyses, we predict that these pairs of proteins are responsible for the biosynthesis of CDP-6-d-glucitol and/or CDP-d-mannitol in the lipopolysaccharides (LPSs) and capsular polysaccharides in more than 200 other organisms. In addition, high resolution X-ray structures of the second enzyme are reported, which provide novel insight into the manner in which an open-chain nucleotide-linked sugar is harbored in an active site cleft.

Insights into the influence of three types of sugar on goose fatty liver formation from endoplasmic reticulum stress (ERS)

This study analyzed the formation of goose fatty liver due to endoplasmic reticulum stress (ERS) caused by 3 types of sugar. Transcriptome analysis was performed for liver tissues from geese fed a traditional diet (maize flour), geese overfed with traditional diet, and geese overfed with diet supplemented with glucose, fructose, or sucrose. Correlation analysis of the liver tissue transcriptomes showed that differentially expressed genes (DEGs) involved in ERS were significantly negatively correlated with DEGs involved in inflammation response in the sucrose overfeeding group, and significantly positively correlated with the DEGs involved in lipid metabolism in fructose overfeeding group. Goose primary hepatocytes were isolated in vitro and then treated with glucose or fructose. Some were also treated with ERS inhibitor 4-phenylbutyric acid (4-PBA). In the hepatocytes, mRNA expression of X-Box Binding Protein 1 (XBP1), activating transcription factor 6 (AFT6) and glucose-regulated protein 78 (GRP78) genes increased in the two sugar groups (glucose and fructose), but were suppressed by adding 4-PBA. The mRNA expression data, protein kinase contents, and triglyceride (TG) and very low-density lipoprotein (VLDL) concentrations all suggest that ERS regulates lipid deposition induced by glucose and fructose via elevating lipid synthesis, inhibiting fatty acid oxidation, and decreasing lipid transportation. In conclusion, glucose, or fructose cause ERS and then ERS causes lipid deposition in goose primary hepatocytes. Three types of sugar cause lipid accumulation and then lipid accumulation prevents ERS during goose fatty liver formation, which suggests a potential mechanism protects goose livers from ERS. The different sugars may induce lipid deposition in different ways.

The agavins (Agave carbohydrates) story

Fructans, are carbohydrates defined as fructose-based polymers with countable degree of polymerization (DP) ranging so far from DP3 to DP60. There are different types of fructans depending on their molecular arrangement. They are categorized as linear inulins and levans, neoseries of inulin and levan, branched graminans, and highly branched neofructans, so called agavins (Agave carbohydrates). It is worth to note that agavins are the most recently described type of fructans and they are also the most complex ones. The complexity of these carbohydrates is correlated to their various isomers and degree of polymerization range, which is correlated to their multifunctional application in industry and human health. Here, we narrate the story of the agavins' discovery. This included their chemical characterization, their benefits, biotechnological applications, and drawbacks over human health. Finally, a perspective of the study of agavins and their interactions with other metabolites through metabolomics is proposed.

The role of glucose and fructose on lipid droplet metabolism in human normal bronchial and cancer lung cells by Raman spectroscopy

Fructose is one of the most important monosaccharides in the human diet that the human body needs for proper metabolism. This paper presents an approach to study biochemical changes caused by sugars in human normal bronchial cells (BEpiC) and human cancer lung cells (A549) by Raman spectroscopy and Raman imaging. Results after supplementation of human bronchial and lung cells with fructose are also discussed and compared with results obtained for pure human bronchial and lung cells. Based on Raman techniques we have proved that peaks at 750 cm-1, 1126 cm-1, 1444 cm-1, 1584 cm-1 and 2845 cm-1 can be treated as biomarkers to monitor fructose changes in cells. Results for fructose have been compared with results for glucose. Raman analysis of the bands at 750 cm-1, 1126 cm-1, 1584 cm-1 and 2845 cm-1 for pure BEpiC and A549 cells and BEpiC and A549 after supplementation with fructose and glucose are higher after supplementation with fructose in comparison to glucose. The obtained results shed light on the uninvestigated influence of glucose and fructose on lipid droplet metabolism by Raman spectroscopy methods.

Rootstock vigor dictates the canopy light environment that regulates metabolite profile and internal fruit quality development in peach

Five rootstock cultivars of differing vigor: vigorous ('Atlas™' and 'Bright's Hybrid® 5'), standard ('Krymsk® 86' and 'Lovell') and dwarfing ('Krymsk® 1') grafted with 'Redhaven' as the scion were studied for their impact on productivity, mid-canopy photosynthetic active radiation transmission (i.e., light availability) and internal fruit quality. Αverage yield (kg per tree) and fruit count increased significantly with increasing vigor (trunk cross sectional area, TCSA). Α detailed peach fruit quality analysis on fruit of equal maturity (based on the index of absorbance difference, IAD) coming from trees with equal crop load (no. of fruit cm-2 of TCSA) characterized the direct impact of rootstock vigor on peach internal quality [dry matter content (DMC) and soluble solids concentration (SSC)]. DMC and SSC increased significantly with decreasing vigor and increasing light availability, potentially due to reduced intra-tree shading and better light distribution within the canopy. Physiologically characterized peach fruit mesocarp was further analyzed by non-targeted metabolite profiling using gas chromatography mass spectrometry (GC-MS). Metabolite distribution was associated with rootstock vigor class, mid-canopy light availability and fruit quality characteristics. Fructose, glucose, sorbose, neochlorogenic and quinic acids, catechin and sorbitol were associated with high light environments and enhanced quality traits, while sucrose, butanoic and malic acids related to low light conditions and inferior fruit quality. These outcomes show that while rootstock genotype and vigor are influencing peach tree productivity and yield, their effect on manipulating the light environment within the canopy also plays a significant role in fruit quality development.

PbrbZIP15 promotes sugar accumulation in pear via activating the transcription of the glucose isomerase gene PbrXylA1

The composition and abundance of soluble sugars in mature pear (Pyrus) fruit are important for its acceptance by consumers. However, our understanding of the genes responsible for soluble sugar accumulation remains limited. In this study, a S1-group member of bZIP gene family, PbrbZIP15, was characterized from pear genome through the combined analyses of metabolite and transcriptome data followed by experimental validation. PbrbZIP15, located in nucleus, was found to function in fructose, sucrose, and total soluble sugar accumulation in pear fruit and calli. After analyzing the expression profiles of sugar-metabolism-related genes and the distribution of cis-acting elements in their promoters, the glucose isomerase 1 gene (PbrXylA1), whose corresponding protein catalyzed the isomerization of glucose and fructose in vitro, was identified as a downstream target gene of PbrbZIP15. PbrbZIP15 could directly bind to the G-box element in PbrXylA1 promoter and activate its transcription, as evidenced by chromatin immunoprecipitation-quantitative PCR, yeast one-hybrid, electrophoretic mobility shift assay, and dual-luciferase assay. PbrXylA1, featuring a leucine-rich signal peptide in its N-terminal, was localized to the endoplasmic reticulum. It was validated to play a significant role in fructose, sucrose, and total soluble sugar accumulation in pear fruit and calli, which was associated with the upregulated fructose/glucose ratio. Further studies revealed a positive correlation between the sucrose content and the expression levels of several sucrose-biosynthesis-related genes (PbrFRK3/8, PbrSPS1/3/4/8, and PbrSPP1) in PbrbZIP15-/PbrXylA1-transgenic fruit/calli. In conclusion, our results suggest that PbrbZIP15-induced soluble sugar accumulation during pear development is at least partly attributed to the activation of PbrXylA1 transcription.

Fructose regulates the pentose phosphate pathway and induces an inflammatory and resolution phenotype in Kupffer cells

Over-consumption of fructose in adults and children has been linked to increased risk of non-alcoholic fatty liver disease (NAFLD). Recent studies have highlighted the effect of fructose on liver inflammation, fibrosis, and immune cell activation. However, little work summarizes the direct impact of fructose on macrophage infiltration, phenotype, and function within the liver. We demonstrate that chronic fructose diet decreased Kupffer cell populations while increasing transitioning monocytes. In addition, fructose increased fibrotic gene expression of collagen 1 alpha 1 (Col1a1) and tissue metallopeptidase inhibitor 1 (Timp1) as well as inflammatory gene expression of tumor necrosis factor alpha (Tnfa) and expression of transmembrane glycoprotein NMB (Gpnmb) in liver tissue compared to glucose and control diets. Single cell RNA sequencing (scRNAseq) revealed fructose elevated expression of matrix metallopeptidase 12 (Mmp12), interleukin 1 receptor antagonist (Il1rn), and radical S-adenosyl methionine domain (Rsad2) in liver and hepatic macrophages. In vitro studies using IMKC and J774.1 cells demonstrated decreased viability when exposed to fructose. Additionally, fructose increased Gpnmb, Tnfa, Mmp12, Il1rn, and Rsad2 in unpolarized IMKC. By mass spectrometry, C13 fructose tracing detected fructose metabolites in glycolysis and the pentose phosphate pathway (PPP). Inhibition of the PPP further increased fructose induced Il6, Gpnmb, Mmp12, Il1rn, and Rsad2 in nonpolarized IMKC. Taken together, fructose decreases cell viability while upregulating resolution and anti-inflammatory associated genes in Kupffer cells.

Construction and investigation of multi-enzyme immobilized matrix for the production of HFCS

Enzymes are biological molecules that act as catalysts and speed up the biochemical reactions. The world's biotechnological ventures are development of enzyme productiveness, and advancement of novel techniques for thriving their shelf existence. Nowadays, the most burning questions in enzyme technology are how to improve the enzyme productivity and reuse them. The immobilization of enzymes provides an excellent scope to reuse the enzymes several times to increase productivity. The main aim of the present study is the establishment of an immobilized multi-enzyme bio-system engineering process for the production of High-fructose corn syrup (HFCS) with an industrial focus. In this study, multi-enzyme such as α-amylase, glucoamylase and glucose isomerase were immobilized in various support matrices like sodium alginate, sawdust, sugarcane bagasse, rice bran and combination of alginate with cellulosic materials. The activities of the immobilized multi-enzyme system for the production of HFCS from the starch solution were determined. The multi-enzyme immobilized in sodium alginate shows better fructose conversion than free enzyme. Among the support matrices, multi-enzyme immobilized in sawdust produced total 80.74 mg/mL of fructose from starch solution and it was able to be used in several production cycles. On the other hand, multi-enzyme immobilized in combination of sodium alginate and sawdust produced the maximum amount of fructose (total 84.82 mg/mL). The free enzyme produced 17.25 mg/mL of fructose from the starch solution in only a single cycle. In this study a new fixed bed immobilized multi-enzyme bioreactor system was developed for the production of HFCS directly from starch. This finding will create a new opportunity for the application of immobilized multi-enzyme systems in many sectors of industrial biotechnology.

Bioproduction of Rare d-Allulose from d-Glucose via Borate-Assisted Isomerization

d-Allulose is a low-calorie functional rare sugar with excellent processing suitability and unique physiological efficacy. d-Allulose is primarily produced from d-fructose through enzymatic epimerization, facing the constraints of a low conversion yield and high production cost. In this study, a double-enzyme cascade system with tetraborate-assisted isomerization was constructed for the efficient production of d-allulose from inexpensive d-glucose. With the introduction of sodium tetraborate (STB), capable of forming complexes with diol-bearing sugars, the conversion yield of d-allulose from d-glucose substantially escalated from the initial 17.37% to 44.97%. Furthermore, d-allulose was found to exhibit the most pronounced binding affinity for STB with an association constant of 1980.51 M-1, notably surpassing that of d-fructose (183.31 M-1) and d-glucose (35.37 M-1). Additionally, the structural analysis of the sugar-STB complexes demonstrated that d-allulose reacted with STB via the cis 2,3-hydroxyl groups in the α-furanose form. Finally, the mechanism underlying STB-assisted isomerization was proposed, emphasizing the preferential formation of an allulose-STB complex that effectively shifts the isomerization equilibrium to the allulose side, thereby resulting in high yield of d-allulose. Such an STB-facilitated isomerization system would also provide a guidance for the cost-effective synthesis of other rare sugars.

Valorization potential of Egyptian mango kernel waste product as analyzed via GC/MS metabolites profiling from different cultivars and geographical origins

Increasing attention has been given to mango (Mangifera indica) fruits owing to their characteristic taste, and rich nutritional value. Mango kernels are typically discarded as a major waste product in mango industry, though of potential economic value. The present study aims to outline the first comparison of different mango kernel cvs. originated from different localities alongside Egypt, e.g., Sharqia, Suez, Ismailia, and Giza. Gas chromatography-mass spectroscopy (GC-MS) post silylation analysis revealed that sugars were the major class being detected at 3.5-290.9 µg/mg, with some kernels originating from Sharqia province being the richest amongst other cvs. In consistency with sugar results, sugar alcohols predominated in Sharqia cvs. at 1.3-38.1 µg/mg represented by ribitol, iditol, pinitol, and myo-inositol. No major variation was observed in the fatty acids profile either based on cv. type or localities, with butyl caprylate as a major component in most cvs. identified for the first time in mango. Regarding phenolics, Sedeeq cv. represented the highest level at 18.3 µg/mg and showing distinct variation among cvs. posing phenolics as better classification markers than sugars. Multivariate data analyses (MVA) confirmed that the premium cvs "Aweis and Fons" were less enriched in sugars, i.e., fructose, talose, and glucose compared to the other cvs. Moreover, MVA of Zabdeya cv. collected from three localities revealed clear segregation to be chemically distinct. Sharqia originated mango kernels were rich in sugars (e.g., glucose and fructose), whilst sarcosine esters predominated in other origins.

Physiological and molecular changes of onion (Allium cepa L.) seeds under different aging conditions

BACKGROUND

Onion seeds have limited storage capacity compared to other vegetable seeds. It is crucial to identify the mechanisms that induce tolerance to storage conditions and reduce seed deterioration. To address this goal, an experiment was conducted to evaluate changes in germination, biochemical, physiological, and molecular characteristics of onion seed landraces (Horand, Kazerun landraces and Zargan cultivar) at different aging levels (control, three-days and six-days accelerated aging, and natural aging for one year).

RESULTS

The findings suggest that there was an increase in glucose, fructose, total sugar, and electrolyte leakage in the Horand (HOR), Kazerun (KAZ) landraces, and Zarghan (ZAR) cultivar, with Kazerun exhibiting the greatest increase. The percentage and rate of germination of Kazerun decreased by 54% and 33%, respectively, in six-day accelerated aging compared to the control, while it decreased by 12% and 14%, respectively, in Horand. Protein content decreased with increasing levels of aging, with a decrease of 26% in Kazerun landrace at six days of aging, while it was 16% in Horand landrace. The antioxidant activities of catalase, superoxide dismutase, and glutathione peroxidase decreased more intensively in Kazerun. The expression of AMY1, BMY1, CTR1, and NPR1 genes were lower in Kazerun landraces than in Horand and Zargan at different aging levels.

CONCLUSIONS

The AMY1, BMY1, CTR1, and NPR1 genes play a pivotal role in onion seed germination, and their downregulation under stressful conditions has been shown to decrease germination rates. In addition, the activity of CAT, SOD, and GPx enzymes decreased by seed aging, and the amount of glucose, fructose, total sugar and electrolyte leakage increased, which ultimately led to seed deterioration. Based on the results of this experiment, it is recommended to conduct further studies into the molecular aspects involved in onion seed deterioration. More research on the genes related to this process is suggested, as well as investigating the impact of different priming treatments on the genes expression involved in the onion seed aging process.

Differential consumption of malic acid and fructose in apple musts by Pichia kudriavzevii strains

AIMS

To assess the capability of Pichia kudriavzevii strains isolated from wine, cider, and natural environments in North Patagonia to produce ciders with reduced malic acid levels.

METHODS AND RESULTS

Fermentation kinetics and malic acid consumption were assessed in synthetic media and in regional acidic apple musts. All P. kudriavzevii strains degraded malic acid and grew in synthetic media with malic acid as the sole carbon source. Among these strains, those isolated from cider exhibited higher fermentative capacity, mainly due to increased fructose utilization; however, a low capacity to consume sucrose present in the must was also observed for all strains. The NPCC1651 cider strain stood out for its malic acid consumption ability in high-malic acid Granny Smith apple must. Additionally, this strain produced high levels of glycerol as well as acceptable levels of acetic acid. On the other hand, Saccharomyces cerevisiae ÑIF8 reference strain isolated from Patagonian wine completely consumed reducing sugars and sucrose and showed an important capacity for malic acid consumption in apple must fermentations.

CONCLUSIONS

Pichia kudriavzevii NPCC1651 strain isolated from cider evidenced interesting features for the consumption of malic acid and fructose in ciders.

Efficient production of 2'-fucosyllactose from fructose through metabolically engineered recombinant Escherichia coli

BACKGROUND

The biosynthesis of human milk oligosaccharides (HMOs) using several microbial systems has garnered considerable interest for their value in pharmaceutics and food industries. 2'-Fucosyllactose (2'-FL), the most abundant oligosaccharide in HMOs, is usually produced using chemical synthesis with a complex and toxic process. Recombinant E. coli strains have been constructed by metabolic engineering strategies to produce 2'-FL, but the low stoichiometric yields (2'-FL/glucose or glycerol) are still far from meeting the requirements of industrial production. The sufficient carbon flux for 2'-FL biosynthesis is a major challenge. As such, it is of great significance for the construction of recombinant strains with a high stoichiometric yield.

RESULTS

In the present study, we designed a 2'-FL biosynthesis pathway from fructose with a theoretical stoichiometric yield of 0.5 mol 2'-FL/mol fructose. The biosynthesis of 2'-FL involves five key enzymes: phosphomannomutase (ManB), mannose-1-phosphate guanylytransferase (ManC), GDP-D-mannose 4,6-dehydratase (Gmd), and GDP-L-fucose synthase (WcaG), and α-1,2-fucosyltransferase (FucT). Based on starting strain SG104, we constructed a series of metabolically engineered E. coli strains by deleting the key genes pfkA, pfkB and pgi, and replacing the original promoter of lacY. The co-expression systems for ManB, ManC, Gmd, WcaG, and FucT were optimized, and nine FucT enzymes were screened to improve the stoichiometric yields of 2'-FL. Furthermore, the gene gapA was regulated to further enhance 2'-FL production, and the highest stoichiometric yield (0.498 mol 2'-FL/mol fructose) was achieved by using recombinant strain RFL38 (SG104ΔpfkAΔpfkBΔpgi119-lacYΔwcaF::119-gmd-wcaG-manC-manB, 119-AGGAGGAGG-gapA, harboring plasmid P30). In the scaled-up reaction, 41.6 g/L (85.2 mM) 2'-FL was produced by a fed-batch bioconversion, corresponding to a stoichiometric yield of 0.482 mol 2'-FL/mol fructose and 0.986 mol 2'-FL/mol lactose.

CONCLUSIONS

The biosynthesis of 2'-FL using recombinant E. coli from fructose was optimized by metabolic engineering strategies. This is the first time to realize the biological production of 2'-FL production from fructose with high stoichiometric yields. This study also provides an important reference to obtain a suitable distribution of carbon flux between 2'-FL synthesis and glycolysis.

Association between higher duodenal levels of the fructose carrier glucose transporter-5 and nonalcoholic fatty liver disease and liver fibrosis

BACKGROUND

An increased dietary fructose intake has been shown to exert several detrimental metabolic effects and contribute to the pathogenesis of nonalcoholic fatty liver disease (NAFLD). An augmented intestinal abundance of the fructose carriers glucose transporter-5 (GLUT-5) and glucose transporter-2 (GLUT-2) has been found in subjects with obesity and type 2 diabetes. Herein, we investigated whether elevated intestinal levels of GLUT-5 and GLUT-2, resulting in a higher dietary fructose uptake, are associated with NAFLD and its severity.

METHODS

GLUT-5 and GLUT-2 protein levels were assessed on duodenal mucosa biopsies of 31 subjects divided into 2 groups based on ultrasound-defined NAFLD presence who underwent an upper gastrointestinal endoscopy.

RESULTS

Individuals with NAFLD exhibited increased duodenal GLUT-5 protein levels in comparison to those without NAFLD, independently of demographic and anthropometric confounders. Conversely, no difference in duodenal GLUT-2 abundance was observed amongst the two groups. Univariate correlation analyses showed that GLUT-5 protein levels were positively related with body mass index, waist circumference, fasting and 2 h post-load insulin concentrations, and insulin resistance (IR) degree estimated by homeostatic model assessment of IR (r = 0.44; p = 0.02) and liver IR (r = 0.46; p = 0.03) indexes. Furthermore, a positive relationship was observed between duodenal GLUT-5 abundance and serum uric acid concentrations (r = 0.40; p = 0.05), a product of fructose metabolism implicated in NAFLD progression. Importantly, duodenal levels of GLUT-5 were positively associated with liver fibrosis risk estimated by NAFLD fibrosis score.

CONCLUSION

Increased duodenal GLUT-5 levels are associated with NAFLD and liver fibrosis. Inhibition of intestinal GLUT-5-mediated fructose uptake may represent a strategy for prevention and treatment of NAFLD.

The polyol pathway and nuclear ketohexokinase A signaling drive hyperglycemia-induced metastasis of gastric cancer

Diabetes might be associated with increased cancer risk, with several studies reporting hyperglycemia as a primary oncogenic stimulant. Since glucose metabolism is linked to numerous metabolic pathways, it is difficult to specify the mechanisms underlying hyperglycemia-induced cancer progression. Here, we focused on the polyol pathway, which is dramatically activated under hyperglycemia and causes diabetic complications. We investigated whether polyol pathway-derived fructose facilitates hyperglycemia-induced gastric cancer metastasis. We performed bioinformatics analysis of gastric cancer datasets and immunohistochemical analyses of gastric cancer specimens, followed by transcriptomic and proteomic analyses to evaluate phenotypic changes in gastric cancer cells. Consequently, we found a clinical association between the polyol pathway and gastric cancer progression. In gastric cancer cell lines, hyperglycemia enhanced cell migration and invasion, cytoskeletal rearrangement, and epithelial-mesenchymal transition (EMT). The hyperglycemia-induced acquisition of metastatic potential was mediated by increased fructose derived from the polyol pathway, which stimulated the nuclear ketohexokinase-A (KHK-A) signaling pathway, thereby inducing EMT by repressing the CDH1 gene. In two different xenograft models of cancer metastasis, gastric cancers overexpressing AKR1B1 were found to be highly metastatic in diabetic mice, but these effects of AKR1B1 were attenuated by KHK-A knockdown. In conclusion, hyperglycemia induces fructose formation through the polyol pathway, which in turn stimulates the KHK-A signaling pathway, driving gastric cancer metastasis by inducing EMT. Thus, the polyol and KHK-A signaling pathways could be potential therapeutic targets to decrease the metastatic risk in gastric cancer patients with diabetes.

Ingestion of Bean Leaves Reduces Metabolic Complications and Restores Intestinal Integrity in C57BL/6 Mice with Obesity Induced by a High-Fat and High-Fructose Diet

Consumption of foods with fiber and compounds can promote gastrointestinal health and reduce obesity complications. Therefore, treatment with common bean leaves (BL) against obesity was evaluated in mice with a high-fat and high-fructose diet (HFFD) for 14 weeks. The bromatological and phytochemical characterization of BL were determined. Afterwards, the animals were supplemented with BL (10%) or a standard diet (SD) as a strategy to encourage a healthy diet for 12 additional weeks. Changes in body composition, lipid profile, and intestinal integrity were analyzed. The characterization of BL stood out for its content of 27.2% dietary fiber, total phenolics (475.04 mg/100 g), and saponins (2.2 mg/100 g). The visceral adipose tissue (VAT) decreased in the BL group by 52% compared to the HFFD group. Additionally, triglyceride levels were 23% lower in the BL consumption group compared to the HFFD group. The improvement in lipid profile was attributed to the 1.77-fold higher fecal lipid excretion in the BL consumption group compared to the HFFD group and the inhibition of pancreatic lipase by 29%. Furthermore, BL supplementation reduced the serum levels of IL-6 (4.4-fold) and FITC-dextran by 50% compared with those in the HFFD group. Metabolic endotoxemia was inhibited after BL supplementation (-33%) compared to the HFFD group. BL consumption as a treatment in obese mice reduces adipose tissue accumulation and improves the lipid profile. Furthermore, we report for the first time that BL consumption improves intestinal integrity.

Fructose Consumption Affects Placental Production of H2S: Impact on Preeclampsia-Related Parameters

H2S, a gasotransmitter that can be produced both via the transsulfuration pathway and non-enzymatically, plays a key role in vasodilation and angiogenesis during pregnancy. In fact, the involvement of H2S production on plasma levels of sFLT1, PGF, and other molecules related to preeclampsia has been demonstrated. Interestingly, we have found that maternal fructose intake (a common component of the Western diet) affects tissular H2S production. However, its consumption is allowed during pregnancy. Thus, (1) to study whether maternal fructose intake affects placental production of H2S in the offspring, when pregnant; and (2) to study if fructose consumption during pregnancy can increase the risk of preeclampsia, pregnant rats from fructose-fed mothers (10% w/v) subjected (FF) or not (FC) to a fructose supplementation were studied and compared to pregnant control rats (CC). Placental gene expression, H2S production, plasma sFLT1, and PGF were determined. Descendants of fructose-fed mothers (FC) presented an increase in H2S production. However, if they consumed fructose during their own gestation (FF), this effect was reversed so that the increase disappeared. Curiously, placental synthesis of H2S was mainly non-enzymatic. Related to this, placental expression of Cys dioxygenase, an enzyme involved in Cys catabolism (a molecule required for non-enzymatic H2S synthesis), was significantly decreased in FC rats. Related to preeclampsia, gene expression of sFLT1 (a molecule with antiangiogenic properties) was augmented in both FF and FC dams, although these differences were not reflected in their plasma levels. Furthermore, placental expression of PGF (a molecule with angiogenic properties) was decreased in both FC and FF dams, becoming significantly diminished in plasma of FC versus control dams. Both fructose consumption and maternal fructose intake induce changes in molecules that contribute to increasing the risk of preeclampsia, and these effects are not always mediated by changes in H2S production.

Unveiling the fructose metabolism system in Staphylococcus aureus: insights into the regulatory role of FruR and the FruRKT operon in bacterial fitness

BACKGROUND

The utilization of fructose as a carbon source and energy provider plays a crucial role in bacterial metabolism. Additionally, fructose metabolism directly impacts the pathogenicity and virulence of certain pathogenic microorganisms.

RESULTS

In this study, we report the discovery of a fructose phosphotransferase system (PTS) in S. aureus. This system comprises three genes, namely fruR, fruK, and fruT, which are co-located in an operon that is indispensable for fructose utilization in S. aureus. Our findings confirm that these three genes are transcribed from a single promoter located upstream of the fruRKT operon. The fruR gene encodes a DeoR-type transcriptional regulator, designated as FruR, which represses the expression of the fruRKT operon by direct binding to its promoter region. Significantly, our experimental data demonstrate that the fruRKT operon can be induced by fructose, suggesting a potential regulatory mechanism involving intracellular fructose-1-phosphate as a direct inducer. Furthermore, we conducted RNA-seq analysis to investigate the specificity of FruR regulation in S. aureus, revealing that the fruRKT operon is predominantly regulated by FruR.

CONCLUSIONS

In summary, this study has uncovered a fructose phosphotransferase system (PTS) in S. aureus, highlighting the essential role of the fruR, fruK, and fruT genes in fructose utilization. We confirmed their co-location within an operon and established FruR as a key regulator by binding to the operon's promoter. Importantly, we demonstrated that fructose can induce this operon, possibly through intracellular fructose-1-phosphate. Our identification of this PTS system represents the initial characterization of a fructose metabolism system in S. aureus.

Fructose-induced perturbation in cellular proteostasis via RPS6KB1 promotes hepatic steatosis

Dietary fructose intake through increased consumption of refined sugar induces hepatic de novo lipogenesis (DNL), a major contributor to hepatic steatosis in NAFLD, however, it's mechanism is not completely understood. Using HepG2 cells, we show that fructose induced DNL involves ribosomal protein S6 kinase B1 (RPS6KB1) driven augmentation of hepatic protein synthesis. This consequently results in endoplasmic reticulum (ER)-stress induced expression of pro-lipogenic gene, fatty acid synthase (FASN). Additionally, the inhibition of fructose induced protein synthesis by either cycloheximide (CHX) or an RPS6KB1 inhibitor significantly reduced both ER-stress and FASN expression. Additionally, corroborating with our in vitro results, the analysis of human NAFLD transcriptomic datasets showed significant upregulation of protein synthesis pathways in the liver of patients with hepatic steatosis, thus linking protein synthesis to lipid accumulation during the early stages of NAFLD. Our results, therefore, demonstrate that RPS6KB1 driven "translation overdrive" coupled with ER-stress contributes to lipogenic gene transcription, and propose RPS6KB1 inhibition as a therapeutic strategy to counter fructose induced hepatic steatosis in NAFLD.

Widely targeted quantitative lipidomics reveal lipid remodeling in adipose tissue after long term of the combined exposure to bisphenol A and fructose

Adipose tissue is the main organ that stores lipids and it plays important roles in metabolic balance in the body. We recently reported in Human and Experimental Toxicology that the combined exposure to BPA and fructose may interfere with energy metabolism of adipose tissue. However, it is still unclear whether the combined exposure to BPA and fructose has the possibility to induce lipid remodeling in adipose tissue. In the present study, we performed a widely targeted quantitative lipidomic analysis of the adipose tissue of rats after 6 months of BPA and fructose combined exposure. We totally determined 734 lipid molecules in the adipose tissue of rats. Principal component analysis (PCA) showed the group of the combined exposure to higher-dose (25 μg/kg every other day) BPA and fructose can be distinguished from the groups of control, higher-dose BPA exposure and fructose exposure clearly. Partial least squares-discriminant analysis (PLS-DA) and univariate statistical analysis displayed lipids of PC(18:0_ 20:3), TG(8:0_14:0_16:0), TG(12:0_14:0_16:1), TG(10:0_16:0_16:1), TG(12:0_ 14:0_18:1), TG(14:0_ 16:0_16:1), TG(14:0_14:1_16:1), TG(8:0_ 16:1_16:2), TG(14:1_16:1_ 16:1), TG(16:1_18:1_18:1), TG(16:0_16:1_20:4) and TG(15:0_18:1_ 24:1) may contributed the most to the discrimination. These findings indicated that combined exposure to BPA and fructose has the potential to cause lipid remodeling in adipose tissue.

Turning waste into treasure: Biosynthesis of value-added 2-O-α-glucosyl glycerol and d-allulose from waste cane molasses through an in vitro synthetic biology platform

The efficient and economical conversion of agricultural waste into glycosides and rare sugars is challenging. Herein, an in vitro synthetic bienzyme system consisting of sucrose phosphorylase and d-allulose 3-epimerase was constructed to produce 2-O-α-glucosyl glycerol and d-allulose from cane molasses. Lactic acid in the cane molasses significantly induced sucrose phosphorylase to hydrolyze sucrose instead of glycosylation. Notably, lactic acid significantly inhibited the catalytic performance of d-allulose 3-epimerase only in the presence of Na+ and K+, with an inhibition rate of 75%. After removing lactic acid and metal ions, 116 g/L 2-O-α-glucosyl glycerol and 51 g/L d-allulose were synthesized from 500 mM sucrose in the treated cane molasses with a sucrose consumption rate of 97%. Our findings offer an economically efficient and environmentally friendly pathway for the industrial production of glycosides and rare sugars from food industry waste.

Antibiotics attenuate diet-induced nonalcoholic fatty liver disease without altering intestinal barrier dysfunction

To date the role of the alterations of intestinal microbiota in the development of intestinal barrier dysfunction in settings of nonalcoholic fatty liver disease (NAFLD) has not been fully understood. Here, we assessed the effect of antibiotics on development of NAFLD and their impact on intestinal barrier dysfunction. Male C57BL/6J mice were either pair-fed a liquid control diet (C) or fat- and fructose-rich diet (FFr) +/- antibiotics (AB, ampicillin/vancomycin/metronidazole/gentamycin) for 7 weeks. Fasting blood glucose was determined and markers of liver damage, inflammation, intestinal barrier function, and microbiota composition were assessed. The development of hepatic steatosis with early signs of inflammation found in FFr-fed mice was significantly abolished in FFr+AB-fed mice. Also, while prevalence of bacteria in feces was not detectable and TLR4 ligand levels in portal plasma were at the level of controls in FFr+AB-fed mice, impairments of intestinal barrier function like an increased permeation of xylose and iNOS protein levels persisted to a similar extent in both FFr-fed groups irrespective of AB use. Exposure of everted small intestinal tissue sacs of naïve mice to fructose resulted in a significant increase in tissue permeability and loss of tight junction proteins, being not affected by the presence of AB, whereas the concomitant treatment of tissue sacs with the NOS inhibitor aminoguanidine attenuated these alterations. Taken together, our data suggest that intestinal barrier dysfunction in diet-induced NAFLD in mice may not be predominantly dependent on changes in intestinal microbiota but rather that fructose-induced alterations of intestinal NO-homeostasis might be critically involved.

Role of the phosphotransferase system in the transport of fosfomycin in Escherichia coli

The inducible inner membrane transporters, UhpT and GlpT are considered to be unique fosfomycin transporters. Glucose-6-phosphate, the substrate for UhpT, enhances fosfomycin activity. Previous work indicates that the fructose phosphotransferase system (PTS) might be involved in fosfomycin transport in the bacterial species, Stenotrophomonas maltophilia. Fosfomycin transport in Escherichia coli has been extensively studied and characterised. The current paper addresses the potential fosfomycin transport activity of the fructose PTS in E. coli. Notably, the deletion of both fructose-specific and general PTS proteins in E. coli increases fosfomycin resistance, which indicates that fructose PTS is involved in fosfomycin transport in E. coli. Further, although inactivation of UhpT, the canonical fosfomycin transporter, in E. coli increases fosfomycin resistance by 2-fold, inactivation of genes encoding the PTS increases it by up to 256-fold. Moreover, intracellular accumulation declines in the absence of both transporters, being mutations in the PTS associated with a larger decline. The results presented in this paper re-open the study of fosfomycin transport and reveal the role of the PTS in the transport of this bactericidal antibiotic in E. coli.

Effect of quercetin administration during the first two weeks post-weaning on the development of non-alcoholic fatty liver disease and dyslipidaemia in Sprague Dawley rats fed a high fructose diet

Hepatic steatosis and dyslipidaemia are associated with excessive fructose consumption. We investigated the effect of quercetin intake during the early pre-weaning period on metabolic dysfunction caused by a high fructose diet. Sprague Dawley rats, 21-day-old, were weaned onto standard rat chow and randomly allocated to four groups which either water or 20% fructose solution to drink with or without quercetin (100 mg/kg body mass). Quercetin was administered for two weeks. Thereafter, rats continued on their respective diets for six weeks without quercetin. Terminally, serum triglyceride concentrations were not significantly different (p > 0.05) between males across groups. However, females receiving quercetin alone had lower serum triglyceride levels than those receiving fructose (p < 0.01). Quercetin increased the incidence of hepatic steatosis in female rats. Quercetin intake in the immediate post-weaning period may prevent hypertriglyceridemia. However, female rats receiving quercetin alone are predisposed to hepatic steatosis associated with a high fructose diet.

Transporter mining and metabolic engineering of Escherichia coli for high-level D-allulose production from D-fructose by thermo-swing fermentation

D-Allulose is an ultra-low-calorie sweetener with broad market prospects in the fields of food, beverage, health care, and medicine. The fermentative synthesis of D-allulose is still under development and considered as an ideal route to replace enzymatic approaches for large-scale production of D-allulose in the future. Generally, D-allulose is synthesized from D-fructose through Izumoring epimerization. This biological reaction is reversible, and a high temperature is beneficial to the conversion of D-fructose. Mild cell growth conditions seriously limit the efficiency of producing D-allulose through fermentation. FryABC permease was identified to be responsible for the transport of D-allulose in Escherichia coli by comparative transcriptomic analysis. A cell factory was then developed by expression of ptsG-F, dpe, and deletion of fryA, fruA, manXYZ, mak, and galE. The results show that the newly engineered E. coli was able to produce 32.33 ± 1.33 g L-1 of D-allulose through a unique thermo-swing fermentation process, with a yield of 0.94 ± 0.01 g g-1 on D-fructose.

Fructose sweetens the adipocyte-T cell alliance against tumors

Dietary fructose is implicated in tumorigenesis, but whether dietary fructose regulates antitumor immunity remains elusive. In this issue of Cell Metabolism, Zhang et al. show that dietary fructose promotes adipocyte-derived leptin production, which attenuates terminal exhaustion programming and boosts the effector function of CD8+ T cells for improved tumor control.

Fructose: a modulator of intestinal barrier function and hepatic health?

PURPOSE

Consumption of fructose has repeatedly been discussed to be a key factor in the development of health disturbances such as hypertension, diabetes type 2, and non-alcoholic fatty liver disease. Despite intense research efforts, the question if and how high dietary fructose intake interferes with human health has not yet been fully answered.

RESULTS

Studies suggest that besides its insulin-independent metabolism dietary fructose may also impact intestinal homeostasis and barrier function. Indeed, it has been suggested by the results of human and animal as well as in vitro studies that fructose enriched diets may alter intestinal microbiota composition. Furthermore, studies have also shown that both acute and chronic intake of fructose may lead to an increased formation of nitric oxide and a loss of tight junction proteins in small intestinal tissue. These alterations have been related to an increased translocation of pathogen-associated molecular patterns (PAMPs) like bacterial endotoxin and an induction of dependent signaling cascades in the liver but also other tissues.

CONCLUSION

In the present narrative review, results of studies assessing the effects of fructose on intestinal barrier function and their impact on the development of health disturbances with a particular focus on the liver are summarized and discussed.

Fructose overconsumption impairs hepatic manganese homeostasis and ammonia disposal

Arginase, a manganese (Mn)-dependent enzyme, is indispensable for urea generation and ammonia disposal in the liver. The potential role of fructose in Mn and ammonia metabolism is undefined. Here we demonstrate that fructose overconsumption impairs hepatic Mn homeostasis and ammonia disposal in male mice. Fructose overexposure reduces liver Mn content as well as its activity of arginase and Mn-SOD, and impairs the clearance of blood ammonia under liver dysfunction. Mechanistically, fructose activates the Mn exporter Slc30a10 gene transcription in the liver in a ChREBP-dependent manner. Hepatic overexpression of Slc30a10 can mimic the effect of fructose on liver Mn content and ammonia disposal. Hepatocyte-specific deletion of Slc30a10 or ChREBP increases liver Mn contents and arginase activity, and abolishes their responsiveness to fructose. Collectively, our data establish a role of fructose in hepatic Mn and ammonia metabolism through ChREBP/Slc30a10 pathway, and postulate fructose dietary restriction for the prevention and treatment of hyperammonemia.

Bioactive dipeptides mitigate high-fat and high-fructose corn syrup diet-induced metabolic-associated fatty liver disease via upregulation of Nrf2/HO-1 expressions in C57BL/6J mice

Metabolic-associated fatty liver disease (MAFLD), formerly referred to as non-alcoholic fatty liver disease (NAFLD), is a common liver disease characterized by an abnormal buildup of fat in liver. This study aimed to investigate whether bioactive dipeptides mitigate high-fat and high-fructose corn syrup diet (HFFD)-induced MAFLD in C57BL/6J mice. Sixty male C57BL/6J mice were randomly divided into six groups. The naïve group (untreated) was fed a standard chow diet and other groups were fed with HFFD along with vehicle and bioactive dipeptides treatment throughout experiment period. The control group received vehicle, YF10 and YF50 groups received Tyr-Phe, 10 and 50 mg/kg/day, FY10 and FY50 groups received Phe-Tyr, 10 and 50 mg/kg/day. At the end of experiment, body weight was recorded, and glucose homeostasis was assessed. Mice were sacrificed and blood samples were collected to measure biochemical parameters. Further, liver, visceral fat pads, and other organs were acutely dissected, weighed, and processed. Histopathological and immunohistochemical changes were analyzed. Long-term HFFD feeding resulted in elevated body weight gain, liver weight, visceral adiposity, liver injury, fasting hyperglycemia, hyperinsulinemia, and hyperlipidemia. It also increased severe hepatic steatosis, chronic low-grade inflammation, oxidative stress, mitochondrial dysfunction, and lipid peroxidation. However, bioactive dipeptides dose-dependently alleviated these complications which are associated with MAFLD by modulating adipokines secretion and antioxidant defense system via upregulation of Nrf2/HO-1 expressions. This study highlights potential of bioactive dipeptides as a promising approach for prevention and/or treatment of MAFLD induced by HFFD, providing novel insights into alternative therapeutic strategies.

Effects of water stress on endogenous hormones and free polyamines in different tissues of grapevines (Vitis vinifera L. cv. 'Merlot')

Water stress can affect plant ecological distribution, crop growth and carbohydrate distribution, impacting berry quality. However, previous studies mainly focused on short-term water stress or osmotic stress and few studies paid attention to the responses of grape to long-term water stresses. Grapevines were subjected to no water stress (CK), mild water stress (T1) and moderate water stress (T2). Hundred-berry weight and malic acid content were reduced under T1 and T2; however, glucose and fructose content showed the opposite trend. Endogenous hormones and polyamines (PAs) can regulate plant growth and development as well as physiological metabolic processes. T1 and T2 could increase abscisic acid content, however, indole-3-acetic acid, jasmonate, gibberellins 3 and 4, cytokinin and trans -zeatin contents were slightly decreased. Three species of PAs (putrescine, spermidine and spermine) were detected, presenting obvious tissue specificity. Furthermore, there was a statistically positive correlation relating spermidine content in the pulp with glucose and fructose contents of grape berries; and a negative correlation with organic acid. In summary, water stress had a profound influence on hormonally-driven changes in physiology and berry quality, indicating that endogenous hormones and the PAs play a critical role in the development and ripening of grape berries under water stress.

Effects of feed additives on rumen function and bacterial and archaeal communities during a starch and fructose challenge

The objective of this study was to improve understandings of the rumen microbial ecosystem during ruminal acidosis and responses to feed additives to improve prudent use strategies for ruminal acidosis control. Rumen bacterial and archaeal community composition (BCC) and its associations with rumen fermentation measures were examined in Holstein heifers fed feed additives and challenged with starch and fructose. Heifers (n = 40) were randomly allocated to 5 treatment groups: (1) control (no additives); (2) virginiamycin (VM; 200 mg/d); (3) monensin (MT; 200 mg/d) + tylosin (110 mg/d); (4) monensin (MLY; 220 mg/d) + live yeast (5.0 × 1012 cfu/d); (5) sodium bicarbonate (BUF; 200 g/d) + magnesium oxide (30 g/d). Heifers were fed twice daily a 62% forage:38% concentrate total mixed ration at 1.25% of body weight (BW) dry matter (DM)/d for a 20-d adaptation period with their additive(s). Fructose (0.1% of BW/d) was added to the ration for the last 10 d of adaptation. On d 21 heifers were challenged once with a ration consisting of 1.0% of BW DM wheat and 0.2% of BW fructose plus their additive(s). A rumen sample was collected from each heifer via stomach tube weekly (d 0, 7, 14) and 5 times over a 3.6 h period at 5, 65, 115, 165, and 215 min after consumption of the challenge ration (d 21) and analyzed for pH, and ammonia, d- and l-lactate, volatile fatty acids (VFA), and histamine concentrations and total bacteria and archaea. The 16S rRNA gene spanning the V4 region was PCR amplified and sequenced. Alpha and β diversity and associations of relative abundances of taxa with rumen fermentation measures were evaluated. Rumen BCC shifted among treatment groups in the adaptation period and across the challenge sampling period, indicating the feed additives had different modes of action. The monensin-containing treatment groups, MT and MLY often had similar relative abundances of rumen bacterial phyla and families. The MLY treatment group was characterized in the challenge period by increased relative abundances of the lactate utilizing genera Anaerovibrio and Megasphaera. The MLY treatment group also had increased diversity of ruminal bacteria which may provide resilience to changes in substrates. The control and BUF treatment groups were most similar in BCC. A redundancy analysis showed the MLY treatment group differed from all other treatment groups and concentrations of histamine and valerate in the rumen were associated with the most variation in the microbiota, 5.3% and 4.8%, respectively. It was evident from the taxa common to all treatment groups that cattle have a core microbiota. Functional redundancy of rumen bacteria which was reflected in the greater sensitivity for the rumen BCC than rumen fermentation measures likely provide resilience to changes in substrate. This functional redundancy of microbes in cattle suggests that there is no single optimal ruminal microbial population and no universally superior feed additive(s). In summary, differences in modes of action suggest the potential for more targeted and improved prudent use of feed additives with no single feed additive(s) providing an optimal BCC in all heifers.

Transcriptome and Metabolome Analyses Reveal Sugar and Acid Accumulation during Apricot Fruit Development

The apricot (Prunus armeniaca L.) is a fruit that belongs to the Rosaceae family; it has a unique flavor and is of important economic and nutritional value. The composition and content of soluble sugars and organic acids in fruit are key factors in determining the flavor quality. However, the molecular mechanism of sugar and acid accumulation in apricots remains unclear. We measured sucrose, fructose, glucose, sorbitol, starch, malate, citric acid, titratable acid, and pH, and investigated the transcriptome profiles of three apricots (the high-sugar cultivar 'Shushanggan', common-sugar cultivar 'Sungold', and low-sugar cultivar 'F43') at three distinct developmental phases. The findings indicated that 'Shushanggan' accumulates a greater amount of sucrose, glucose, fructose, and sorbitol, and less citric acid and titratable acid, resulting in a better flavor; 'Sungold' mainly accumulates more sucrose and less citric acid and starch for the second flavor; and 'F43' mainly accumulates more titratable acid, citric acid, and starch for a lesser degree of sweetness. We investigated the DEGs associated with the starch and sucrose metabolism pathways, citrate cycle pathway, glycolysis pathway, and a handful of sugar transporter proteins, which were considered to be important regulators of sugar and acid accumulation. Additionally, an analysis of the co-expression network of weighted genes unveiled a robust correlation between the brown module and sucrose, glucose, and fructose, with VIP being identified as a hub gene that interacted with four sugar transporter proteins (SLC35B3, SLC32A, SLC2A8, and SLC2A13), as well as three structural genes for sugar and acid metabolism (MUR3, E3.2.1.67, and CSLD). Furthermore, we found some lncRNAs and miRNAs that regulate these genes. Our findings provide clues to the functional genes related to sugar metabolism, and lay the foundation for the selection and cultivation of high-sugar apricots in the future.

Different Effects of High-Fat/High-Sucrose and High-Fructose Diets on Advanced Glycation End-Product Accumulation and on Mitochondrial Involvement in Heart and Skeletal Muscle in Mice

Diets with an elevated content of fat, sucrose, or fructose are recognized models of diet-induced metabolic alterations, since they induce metabolic derangements, oxidative stress, and chronic low-grade inflammation associated with local and systemic accumulation of advanced glycation end-products (AGEs). This study used four-week-old C57BL/6 male mice, randomly assigned to three experimental dietary regimens: standard diet (SD), high-fat high-sucrose diet (HFHS), or high fructose diet (HFr), administered for 12 weeks. Plasma, heart, and tibialis anterior (TA) skeletal muscle were assayed for markers of metabolic conditions, inflammation, presence of AGEs, and mitochondrial involvement. The HFHS diet induced a tissue-specific differential response featuring (1) a remarkable adaptation of the heart to HFHS-induced heavy oxidative stress, demonstrated by an increased presence of AGEs and reduced mitochondrial biogenesis, and efficaciously counteracted by a conspicuous increase in mitochondrial fission and PRXIII expression; (2) the absence of TA adaptation to HFHS, revealed by a heavy reduction in mitochondrial biogenesis, not counteracted by an increase in fission and PRXIII expression. HFr-induced mild oxidative stress elicited tissue-specific responses, featuring (1) a decrease in mitochondrial biogenesis in the heart, likely counteracted by a tendency for increased fission and (2) a mild reduction in mitochondrial biogenesis in TA, likely counteracted by a tendency for increased fusion, showing the adaptability of both tissues to the diet.