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1.
Improved resource allocation and stabilization of yield under abiotic stress.
Keller, I, Rodrigues, CM, Neuhaus, HE, Pommerrenig, B
Journal of plant physiology. 2021;:153336
Abstract
Sugars are the main building blocks for carbohydrate storage, but also serve as signaling molecules and protective compounds during abiotic stress responses. Accordingly, sugar transport proteins fulfill multiple roles as they mediate long distance sugar allocation, but also shape the subcellular and tissue-specific carbohydrate profiles by balancing the levels of these molecules in various compartments. Accordingly, transporter activity represents a target by classical or directed breeding approaches, to either, directly increase phloem loading or to increase sink strength in crop species. The relative subcellular distribution of sugars is critical for molecular signaling affecting yield-relevant processes like photosynthesis, onset of flowering and stress responses, while controlled long-distance sugar transport directly impacts development and productivity of plants. However, long-distance transport is prone to become unbalanced upon adverse environmental conditions. Therefore, we highlight the influence of stress stimuli on sucrose transport in the phloem and include the role of stress induced cellular carbohydrate sinks, like raffinose or fructans, which possess important roles to build up tolerance against challenging environmental conditions. In addition, we report on recent breeding approaches that resulted in altered source and sink capacities, leading to increased phloem sucrose shuttling in crops. Finally, we present strategies integrating the need of cellular stress-protection into the general picture of long-distance transport under abiotic stress, and point to possible approaches improving plant performance and resource allocation under adverse environmental conditions, leading to stabilized or even increased crop yield.
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2.
The plant axis as the command centre for (re)distribution of sucrose and amino acids.
van Bel, AJE
Journal of plant physiology. 2021;:153488
Abstract
Along with the increase in size required for optimal colonization of terrestrial niches, channels for bidirectional bulk transport of materials in land plants evolved during a period of about 100 million years. These transport systems are essentially still in operation - though perfected over the following 400 million years - and make use of hydrostatic differentials. Substances are accumulated or released at the loading and unloading ends, respectively, of the transport channels. The intermediate stretch between the channel termini is bifunctional and executes orchestrated release and retrieval of solutes. Analyses of anatomical and physiological data demonstrate that the release/retrieval zone extends deeper into sources and sinks than is commonly thought and covers usually much more than 99% of the translocation stretch. This review sketches the significance of events in the intermediate stretch for distribution of organic materials over the plant body. Net leakage from the channels does not only serve maintenance and growth of tissues along the pathway, but also diurnal, short-term or seasonal storage of reserve materials, and balanced distribution of organic C- and N-compounds over axial and terminal sinks. Release and retrieval are controlled by plasma-membrane transporters at the vessel/parenchyma interface in the contact pits along xylem vessels and by plasma-membrane transporters at the interface between companion cells and phloem parenchyma along sieve tubes. The xylem-to-phloem pathway vice versa is a bifacial, radially oriented system comprising a symplasmic pathway, of which entrance and exit are controlled at specific membrane checkpoints, and a parallel apoplasmic pathway. A broad range of specific sucrose and amino-acid transporters are deployed at the checkpoint plasma membranes. SUCs, SUTs, STPs, SWEETs, and AAPs, LTHs, CATs are localized to the plasma membranes in question, both in monocots and eudicots. Presence of Umamits in monocots is uncertain. There is some evidence for endo- and exocytosis at the vessel/parenchyma interface supplementary to the transporter-mediated uptake and release. Actions of transporters at the checkpoints are equally decisive for storage and distribution of amino acids and sucrose in monocots and eudicots, but storage and distribution patterns may differ between both taxa. While the majority of reserves is sequestered in vascular parenchyma cells in dicots, lack of space in monocot vasculature urges "outsourcing" of storage in ground parenchyma around the translocation path. In perennial dicots, specialized radial pathways (rays) include the sites for seasonal alternation of storage and mobilization. In dicots, apoplasmic phloem loading and a correlated low rate of release along the path would favour supply with photoassimilates of terminal sinks, while symplasmic phloem loading and a correlated higher rate of release along the path favours supply of axial sinks and transfer to the xylem. The balance between the resource acquisition by terminal and axial sinks is an important determinant of relative growth rate and, hence, for the fitness of plants in various habitats. Body enlargement as the evolutionary drive for emergence of vascular systems and mass transport propelled by hydrostatic differentials.
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3.
Assessment of small-intestine permeability in healthy Nigerian children is altered by urinary volume and voiding status.
Afolami, I, Samuel, FO, Mwangi, M, Oderinde, M, Diepeveen-de Bruin, M, Melse-Boonstra, A
PloS one. 2021;(9):e0253436
Abstract
OBJECTIVE This study aimed to uncover the effect of voided urinary volume on small intestine permeability ratios in healthy children. METHODS We assessed small intestine permeability in 155 apparently healthy children, aged 3-5 years old, without any visible symptoms of disease, in a rural, malaria-endemic setting in Nigeria, using a multi-sugar test solution, comprising lactulose, sucrose, mannitol, and rhamnose. Children were categorized into low urinary volume (LV) and high urinary volume (HV), based on the volume of urine voided per kg body weight per hour. LV children voided less than 25th percentile of the total population, while HV children voided greater than 75th percentile of the total population. Urinary volume excreted over a 90-minute period after administration of the test solution was measured, and differences in sugar ratios were compared between children with high (HV) and low urinary volumes (LV), as well as between children who voided (VC) or who were not able to void (NVC) before administration of the test solution. RESULTS Urinary mannitol and rhamnose recovery were 44% (p = 0.002) and 77% (p<0.001) higher in HV children compared to LV children respectively, while urinary lactulose recovery was 34% lower (p = 0.071). There was no difference in urinary sucrose recovery between groups (p = 0.74). Lactulose-mannitol ratio, lactulose-rhamnose ratio and sucrose-rhamnose ratio were all significantly higher in children in the LV group compared to children in the HV group (p<0.001). In a multiple regression analysis, urinary volume and voiding status combined, explained 13%, 23% and 7% of the variation observed in lactulose-mannitol, lactulose-rhamnose and sucrose-rhamnose ratios, respectively. CONCLUSION Sugar permeability ratios vary significantly with total urinary volume in multi-sugar small-intestine permeability tests. Voiding status before sugar administration appears to influence lactulose recovery, lactulose-rhamnose and sucrose-rhamnose ratios independently of total urinary volume. Evidence from this study suggests the need to take urinary volume into account when conducting multi-sugar small-intestine permeability tests.
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4.
Immobilization of Serratia plymuthica by ionic gelation and cross-linking with transglutaminase for the conversion of sucrose into isomaltulose.
Carvalho, PH, Kawaguti, HY, de Souza, WFC, Sato, HH
Bioprocess and biosystems engineering. 2021;(6):1109-1118
Abstract
Isomaltulose is an alternative sugar obtained from sucrose using some bacteria producing glycosyltransferase. This work aimed to optimize conditions for the immobilization of Serratia plymuthica through ionic gelation and cross-linking by transglutaminase using the sequential experimental strategy for the conversion of sucrose into isomaltulose. The effect of five variables (concentrations of cell mass, alginate, gelatin, transglutaminase, and calcium chloride) was studied, as well as the interactions between them on the matrix composition for the S. plymuthica immobilization. Three experimental designs were used to optimize the concentrations of each variable to obtain higher concentration of isomaltulose. A high conversion of sucrose into isomaltulose (71.04%) was obtained by the cells immobilized in a matrix composed of alginate (1.7%), CaCl2 (0.25 mol/L), gelatin (0.5%), transglutaminase (3.5%) and cell mass (33.5%). As a result, the transglutaminase application as a cross-linking agent improved the immobilization of Serratia plymuthica cells and the conversion of sucrose into isomaltulose.
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5.
Orosensory Perception of Fat/Sweet Stimuli and Appetite-Regulating Peptides before and after Sleeve Gastrectomy or Gastric Bypass in Adult Women with Obesity.
Bernard, A, Le Beyec-Le Bihan, J, Radoi, L, Coupaye, M, Sami, O, Casanova, N, Le May, C, Collet, X, Delaby, P, Le Bourgot, C, et al
Nutrients. 2021;(3)
Abstract
The aim of this study was to explore the impact of bariatric surgery on fat and sweet taste perceptions and to determine the possible correlations with gut appetite-regulating peptides and subjective food sensations. Women suffering from severe obesity (BMI > 35 kg/m2) were studied 2 weeks before and 6 months after a vertical sleeve gastrectomy (VSG, n = 32) or a Roux-en-Y gastric bypass (RYGB, n = 12). Linoleic acid (LA) and sucrose perception thresholds were determined using the three-alternative forced-choice procedure, gut hormones were assayed before and after a test meal and subjective changes in oral food sensations were self-reported using a standardized questionnaire. Despite a global positive effect of both surgeries on the reported gustatory sensations, a change in the taste sensitivity was only found after RYGB for LA. However, the fat and sweet taste perceptions were not homogenous between patients who underwent the same surgery procedure, suggesting the existence of two subgroups: patients with and without taste improvement. These gustatory changes were not correlated to the surgery-mediated modifications of the main gut appetite-regulating hormones. Collectively these data highlight the complexity of relationships between bariatric surgery and taste sensitivity and suggest that VSG and RYGB might impact the fatty taste perception differently.
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6.
Using iron-based phosphate binders in phosphate reduction and anemia improvement in patients receiving dialysis: a meta-analysis of randomized controlled trials.
Zhu, Y, Rao, J, Liao, X, Ou, J, Li, W, Xue, C
International urology and nephrology. 2021;(9):1899-1909
Abstract
PURPOSE A study was conducted to determine whether iron-based phosphate binders (IBPBs) need to be preferred for hyperphosphatemia and anemia management in patients on dialysis. METHODS For this meta-analysis, we searched PubMed, Embase, and Cochrane Central Register of Controlled Trials for randomized controlled trials that evaluated the efficacy and safety of IBPBs in decreasing phosphate and correcting anemia in dialysis patients. RESULTS Nineteen trials comprising 4719 participants were included. Compared with placebo, serum phosphate decreased significantly after treatment with ferric citrate (FC), fermagate (one study), and SBR759 (one study). Hemoglobin increased significantly after treatment with FC and sucroferric oxyhydroxide (PA21). In addition, FC and PA21 reduced serum intact parathyroid hormone (iPTH) and increased ferritin and transferrin saturation, but SBR759 did not. Compared with active treatment, the non-inferiority of IBPBs in reducing serum phosphate and iPTH was demonstrated. FC significantly improved serum hemoglobin and iron-related parameters and decreased the use of intravenous iron and erythropoiesis-stimulating agent, whereas PA21 did not increase serum hemoglobin level. The incidences of infection and hospitalization were similar between the two groups, with FC having a higher risk of diarrhea than the placebo and active treatments. CONCLUSION FC was associated with the control of hyperphosphatemia and the improvement of anemia. However, PA21 did not show superiority for alleviating anemia compared with the active treatment. Other IBPBs, such as fermagate and SBR759, remained poorly understood due to the limited number of studies. Further trials are required to assess the effect of IBPBs on the risk of cardiovascular events and all-cause mortality.
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7.
Lower versus standard sucrose dose for treating hypoglycemia in patients with type 1 diabetes mellitus in therapy with predictive low glucose suspend (PLGS) augmented insulin pumps: A randomized crossover trial in Santiago, Chile.
Grassi, B, Onetto, MT, Zapata, Y, Jofré, P, Echeverría, G
Diabetes & metabolic syndrome. 2021;(3):695-701
Abstract
BACKGROUND AND AIMS Recommended hypoglycemia treatment in adults with T1D consists of 15 g of rapid absorption carbohydrates. We aimed to evaluate the response to fewer carbohydrates for treating hypoglycemia in patients with T1D on insulin pumps with predictive suspension technology (PLGS). METHODS T1D patients on insulin pumps with PLGS were randomized to receive 10 or 15 g of sucrose per hypoglycemia for two weeks (S10 and S15 groups, respectively) when capillary blood glucose (BG) was <70 mg/dL, with crossover after two weeks. Evolution of capillary BG, active insulin, and suspension time were assessed. RESULTS 59 hypoglycemic episodes were analyzed, 33 in S10 and 26 in S15. Baseline BG in S10 was 54.3 ± 7.7 mg/dL versus 56.9 ± 8.8 in S15 (p = 0,239). Active insulin, present in 85% of the episodes, and PLGS suspension time were similar between groups. BG at 15 min was 77 mg/dL in S10 and 95 mg/dL in S15 (p = 0.0007). In S10, 21% of the episodes required to repeat the treatment after 15 min compared with none on S15, with a RR of 0,79 (95% CI 0.66, 0.940, p = 0,014) for successfully treating the episode. Sensor glucose was significantly different from BG at the moment of the hypoglycemia and control 15 min after treatment. No severe hypoglycemia and no rebound hyperglycemia occurred in neither group. CONCLUSIONS A hypoglycemia treatment protocol with a lower dose of sucrose might be insufficient despite PLGS technology. Our data suggest that standard doses of sucrose should still be recommended.
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8.
Consuming Sucrose- or HFCS-sweetened Beverages Increases Hepatic Lipid and Decreases Insulin Sensitivity in Adults.
Sigala, DM, Hieronimus, B, Medici, V, Lee, V, Nunez, MV, Bremer, AA, Cox, CL, Price, CA, Benyam, Y, Chaudhari, AJ, et al
The Journal of clinical endocrinology and metabolism. 2021;(11):3248-3264
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Abstract
CONTEXT Studies in rodents and humans suggest that high-fructose corn syrup (HFCS)-sweetened diets promote greater metabolic dysfunction than sucrose-sweetened diets. OBJECTIVE To compare the effects of consuming sucrose-sweetened beverage (SB), HFCS-SB, or a control beverage sweetened with aspartame on metabolic outcomes in humans. METHODS A parallel, double-blinded, NIH-funded study. Experimental procedures were conducted during 3.5 days of inpatient residence with controlled feeding at a research clinic before (baseline) and after a 12-day outpatient intervention period. Seventy-five adults (18-40 years) were assigned to beverage groups matched for sex, body mass index (18-35 kg/m2), and fasting triglyceride, lipoprotein and insulin concentrations. The intervention was 3 servings/day of sucrose- or HFCS-SB providing 25% of energy requirement or aspartame-SB, consumed for 16 days. Main outcome measures were %hepatic lipid, Matsuda insulin sensitivity index (ISI), and Predicted M ISI. RESULTS Sucrose-SB increased %hepatic lipid (absolute change: 0.6 ± 0.2%) compared with aspartame-SB (-0.2 ± 0.2%, P < 0.05) and compared with baseline (P < 0.001). HFCS-SB increased %hepatic lipid compared with baseline (0.4 ± 0.2%, P < 0.05). Compared with aspartame-SB, Matsuda ISI decreased after consumption of HFCS- (P < 0.01) and sucrose-SB (P < 0.01), and Predicted M ISI decreased after consumption of HFCS-SB (P < 0.05). Sucrose- and HFCS-SB increased plasma concentrations of lipids, lipoproteins, and uric acid compared with aspartame-SB. No outcomes were differentially affected by sucrose- compared with HFCS-SB. Beverage group effects remained significant when analyses were adjusted for changes in body weight. CONCLUSION Consumption of both sucrose- and HFCS-SB induced detrimental changes in hepatic lipid, insulin sensitivity, and circulating lipids, lipoproteins and uric acid in 2 weeks.
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Sucrose interferes with endogenous cytokinin homeostasis and expression of organogenesis-related genes during de novo shoot organogenesis in kohlrabi.
Ćosić, T, Motyka, V, Savić, J, Raspor, M, Marković, M, Dobrev, PI, Ninković, S
Scientific reports. 2021;(1):6494
Abstract
Cross-talk between phytohormones and sugars is intensely involved in plant metabolism, growth and regeneration. We documented alterations in cytokinin (CK) homeostasis in four developmental stages during de novo shoot organogenesis (DNSO) of kohlrabi (Brassica oleracea var. gongylodes cv. Vienna Purple) seedlings induced by exogenous CKs, trans-zeatin (transZ) and thidiazuron (TDZ), added together with elevated sucrose concentration (6% and 9%). Significant impact of CK and sucrose treatment and their interaction was recorded in all investigated stages, including plantlet development before calli formation (T1 and T2), calli formation (T3) and shoot regeneration (T4). Results showed remarkable increase in total CK levels for transZ treatment, particularly with 9% sucrose. This trend was observed for all physiological and structural groups of CKs. Application of TDZ contributed to little or no increase in CK levels regardless of sucrose concentration. Analysis of expression profiles of organogenesis-related genes involved in auxin transport, CK response, shoot apical meristem formation and cell division revealed that higher sugar concentration significantly downregulated the analysed genes, particularly in T3. This continued on TDZ, but transZ induced an opposite effect with 9% sucrose in T4, increasing gene activity. Our results demonstrated that phytohormone metabolism might be triggered by sucrose signalling in kohlrabi DNSO.
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A Pilot Study Comparing the Effects of Consuming 100% Orange Juice or Sucrose-Sweetened Beverage on Risk Factors for Cardiometabolic Disease in Women.
Price, CA, Medici, V, Nunez, MV, Lee, V, Sigala, DM, Benyam, Y, Keim, NL, Mason, AE, Chen, SY, Parenti, M, et al
Nutrients. 2021;(3)
Abstract
Overconsumption of sugar-sweetened beverages increases risk factors associated with cardiometabolic disease, in part due to hepatic fructose overload. However, it is not clear whether consumption of beverages containing fructose as naturally occurring sugar produces equivalent metabolic dysregulation as beverages containing added sugars. We compared the effects of consuming naturally-sweetened orange juice (OJ) or sucrose-sweetened beverages (sucrose-SB) for two weeks on risk factors for cardiometabolic disease. Healthy, overweight women (n = 20) were assigned to consume either 3 servings of 100% orange juice or sucrose-SB/day. We conducted 16-hour serial blood collections and 3-h oral glucose tolerance tests during a 30-h inpatient visit at baseline and after the 2-week diet intervention. The 16-h area under the curve (AUC) for uric acid increased in subjects consuming sucrose-SB compared with subjects consuming OJ. Unlike sucrose-SB, OJ did not significantly increase fasting or postprandial lipoproteins. Consumption of both beverages resulted in reductions in the Matsuda insulin sensitivity index (OJ: -0.40 ± 0.18, p = 0.04 within group; sucrose-SB: -1.0 ± 0.38, p = 0.006 within group; p = 0.53 between groups). Findings from this pilot study suggest that consumption of OJ at levels above the current dietary guidelines for sugar intake does not increase plasma uric acid concentrations compared with sucrose-SB, but appears to lead to comparable decreases of insulin sensitivity.