Changes In Carbohydrate Content Research Articles

Viability and integrity of Pinus densiflora seeds stored for 20years at three different temperatures.

Storage temperature is one of the most important factors determining seed longevity in the genebank. This study aimed to investigate the effect of storage temperature on the seed viability and physiological integrity after a 20-year storage period of Pinus densiflora, a tree species of ecological and economic significance in South Korea. To this end, seeds were collected and stored dry for 20years at -18°C, 4°C and 25°C. Germination tests were conducted to assess seed viability and vigour, electrolyte leakage analysis was performed to assess cell membrane integrity, and carbohydrate analysis was conducted to assess metabolic integrity during germination. The results revealed that over 20years, seeds stored at -18°C maintained a high germination percentage (GP; 89%), comparable to initial GP (91%), whilst those stored at 4°C exhibited a decline in GP (44%) along with a decrease in vigour. Seeds stored at 25°C lost their viability entirely. Electrical conductivity of the leachate and leakage of inorganic compounds and soluble sugars were higher with elevated storage temperature, indicating increased imbibition damage. Additionally, changes in carbohydrate content during germination revealed that the loss of viability according to storage temperature is associated with reduced storage reserve utilization and altered carbohydrate metabolism during germination. These results enhance our understanding of the effect of seed storage temperature on longevity and physiological changes of aging in the genebank, serving as a reference for establishing conservation strategies for Pinus densiflora.

Starvation and cadmium affect energy reserves and oxidative stress in individuals of Spodoptera exigua

Different factors, such as starvation and metal exposure, may affect development and cause oxidative stress in insects. Some host plants may contain a high concentration of cadmium due to their hyperaccumulating property. The negative effects of metals and hunger may be manifested by low availability of energetic substrates. This study aimed to assess whether the insect population with a history of long metal exposure may better manage metal stress or/and starvation at different developmental stages, with the use of energetic substrates. Two strains of Spodoptera exigua model organism were tested: control strain and cadmium strain (treated continuously for over 200 generations with subtoxic amounts of cadmium). The effects of different factors, individually and in combination, on the tested strains were assessed, first by determining the body weight of larvae and pupae and then by estimating the concentration of biomolecules (proteins, carbohydrates, lipids, or glycogen) in the 4th and 5th larval stages and in pupae, and the total antioxidant capacity and lipid peroxidation level in the 4th larval stage. Compared to control strain, cadmium strain individuals exhibited changes in the concentration of soluble carbohydrates and protein. This was partly related to earlier 1-day starvation. In particular, changes in carbohydrate concentration seemed to be a sensitive biomarker of metal stress, independent of the age of individuals and period of starvation. However, the increase in the total antioxidant capacity and the concentration of lipid peroxidation products in the 4th larval stage under the effect of cadmium was dependent on strain origin.

Changes in carbohydrate content in mixtures of field pea and spring triticale determining the quality of green fodder

Green fodder obtained from mixtures of legume and cereals can be of good quality for direct feeding. Obtaining good quality fodder from mixtures cultivated on arable land is possible on the condition of proper share of components, harvest time and plant selection. The aim of this study was to evaluate the effect of the share of components in the mixture of pea with spring triticale and the harvest date on carbohydrates content in green matter. A field experiment was conducted from 2016 to 2018 and two factors were studied: I. Share of components in the mixture: field pea - clean sowing, spring triticale - clean sowing, field pea 75% + spring triticale 25%, field pea 50% + spring triticale 50%, field pea 25% + spring triticale 75%. II. Harvest date: flowering stage of field pea, flat green pod stage of field pea. The highest content of total carbohydrates and water soluble carbohydrates, among the mixtures, was found in the mixture with 75% share of pea and 25% share of spring triticale. The harvest date had no effect on the concentration of total carbohydrates, while delaying the harvest date caused a decrease in the water soluble carbohydrates content in the green matter of the mixtures.

Changes on Sugar and Starch Contents during Seed Development of Synergistic Sweet Corn and Implication on Seed Quality

Synergistic sweet corn equipped with multiple-recessive genes encoding sugar synthesis is proposed through hybrid breeding to improve the balance eating quality including flavor, texture, and aroma. However, the drawback on seed quality occurs such as low germination and poor seedling vigor. This study aimed to investigate the changes of carbohydrate contents on seed quality of five sweet corn genotypes differing in the number of equipped recessive genes during seed development. Seeds were sampled at 4-day intervals from 18 to 46 days after pollination (DAP) and analyzed for seed germination, sugar, water-soluble polysaccharide, and starch. Then, their relationships were analyzed by using time series regression analysis. Although there were significant differences among 5 corn genotypes in their seed germination and carbohydrate contents, some genotypes showed responses in similar patterns. The optimal time to harvest seeds was genotype-dependent, which were 38 DAP for triple-recessive gene (btbtsh2sh2wxwx) and single-recessive genes (BtBtsh2sh2WxWx and Sh2Sh2susuWxWx) and 42 DAP for double-recessive genes (BtBtsh2sh2wxwx). The regression analysis revealed that seed germinability could be predicted by total starch content in synergistic sweet corn lines during seed development stages; however, this prediction seemed to be negligible in sweet corn genotypes equipped with a single-recessive gene. Implications and further suggestions for establishing an effective seed production technique and seed quality of synergistic sweet corn are discussed.

Toward a More Comprehensive View of α-Amylase across Decapods Crustaceans.

Simple SummaryDecapod crustaceans live in practically all marine, freshwater, and semi-terrestrial habitats on Earth, and exhibit a remarkable variation in their feeding behavior, from filter feeding, grazing, and scavenging to hunting. However, most knowledge about digestive biochemistry in crustaceans has come from studies on a few economically relevant species due to the importance of optimized formulated feeds for aquaculture success. Moreover, most data on α-amylases in decapods derived from studies in herbivore and omnivore species. There are few reviews addressing different aspects of the digestive physiology of decapods, including data on digestive enzymes, but no comprehensive review is available on α-amylases in this group and, in general, information on carnivorous species is often neglected. This review summarizes the information obtained on decapods’ α-amylases and uses recent data from a carnivorous lobster as a connecting thread to compare features of α-amylases from species with different feeding habits, drawing a more comprehensive view of the role of α-amylases across decapods crustaceans.Decapod crustaceans are a very diverse group and have evolved to suit a wide variety of diets. Alpha-amylases enzymes, responsible for starch and glycogen digestion, have been more thoroughly studied in herbivore and omnivore than in carnivorous species. We used information on the α-amylase of a carnivorous lobster as a connecting thread to provide a more comprehensive view of α-amylases across decapods crustaceans. Omnivorous crustaceans such as shrimps, crabs, and crayfish present relatively high amylase activity with respect to carnivorous crustaceans. Yet, contradictory results have been obtained and relatively high activity in some carnivores has been suggested to be a remnant trait from ancestor species. Here, we provided information sustaining that high enzyme sequence and overall architecture conservation do not allow high changes in activity, and that differences among species may be more related to number of genes and isoforms, as well as transcriptional and secretion regulation. However, recent evolutionary analyses revealed that positive selection might have also occurred among distant lineages with feeding habits as a selection force. Some biochemical features of decapod α-amylases can be related with habitat or gut conditions, while less clear patterns are observed for other enzyme properties. Likewise, while molt cycle variations in α-amylase activity are rather similar among species, clear relationships between activity and diet shifts through development cannot be always observed. Regarding the adaptation of α-amylase to diet, juveniles seem to exhibit more flexibility than larvae, and it has been described variation in α-amylase activity or number of isoforms due to the source of carbohydrate and its level in diets, especially in omnivore species. In the carnivorous lobster, however, no influence of the type of carbohydrate could be observed. Moreover, lobsters were not able to fine-regulate α-amylase gene expression in spite of large changes in carbohydrate content of diet, while retaining some capacity to adapt α-amylase activity to very low carbohydrate content in the diets. In this review, we raised arguments for the need of more studies on the α-amylases of less studied decapods groups, including carnivorous species which rely more on dietary protein and lipids, to broaden our view of α-amylase in decapods crustaceans.

Rats Self-Select a Constant Protein-to-Carbohydrate Ratio Rather Than a Constant Protein-to-Energy Ratio and Have Low Plasma FGF21 Concentrations.

Under dietary self-selection (DSS), rats ingest 25-30% of energy as protein. This high level appears to be explained by metabolic benefits related to reduced carbohydrate dependence and associated pathologies. However, the mechanisms underlying these choices remain largely misunderstood. The aim was to test the hypothesis that in a DSS model, rats select a protein-to-energy (PE) ratio to maintain the protein-to-carbohydrate (PC) ratio constant and that fibroblast growth factor 21 (FGF21) is involved in this response. Adult male Wistar rats were used in 3 experiments. The first was to determine whether the PE ratio was influenced by changes in carbohydrate content. The second was to test whether the PE ratio was defended with a modified DSS model. The third was to determine whether the selected PE ratio was of metabolic interest compared with a standard 15% protein diet. Food intake, body weight, and energy expenditure were measured. After 3 wk, plasma was sampled and rats were killed to determine body composition and gene expression. Statistical analyses were mainly done by ANOVA tests and correlation tests. The selected PE ratio increased from 20% to 35% when the carbohydrate content of the protein-free diet increased from 30% to 75% (R2 = 0.56; P<10-6). Consequently, the PC ratio was constant (70%) in all groups (P=0.18). In self-selecting rats, plasma FGF21 concentrations were 3 times lower than in rats fed the 5% protein diet (P<10-4) and similar to those in rats fed a 30% diet. This study showed that self-selecting rats established PE ratios larger than those considered sufficient to achieve optimal growth in adult rats (10-15%), and the ratios were highly dependent on carbohydrates, apparently with the aim of maintaining a constant and high PC ratio. This was associated with a minimization of plasma FGF21.

Sugar-mediated regulation and the role of HXK1, SnRK1, TOR kinases in &lt;i&gt;Arabidopsis thaliana&lt;/i&gt;

Sugars play an important role in plant metabolism. They are not only a source of energy, but also an integral part of the intracellular signalling network. Signals involving sugars regulate a variety of metabolic reactions, e.g. carbon and nitrogen metabolism, and produce plant response to biotic and abiotic stresses. This paper provides a brief review of modern publications about sugars acting as metabolites and signaling molecules. The well-known and recently discovered pathways for the transmission of sugar-mediated signals are described, along with their role in the regulation of plant metabolism and expression of nuclear genes. Hexokinase 1 (an enzyme for glucose synthesis), which was one of the first studied participants in the sugar-mediated signalling network, regulates the expression of many nuclear genes in response to changes in the glucose level. Hexokinase 1 should be considered as a broad-spectrum regulator due to its participation in the transmission of mitochondrial-nuclear signals and regulation of aging processes in plants, which functions lay beyond the regulation of metabolic reactions. Of particular interest is the participation of sugar-mediated signals in the switching of metabolic reactions in response to changes in carbohydrate concentrations. Sugar deficiency deactivates most energy-intensive processes, at the same time as stimulating photosynthesis or (in its absence) enhancing catabolic reactions due to activation of the SnRK1 kinase. Under sufficient sugar levels, the SnRK1 kinase is suppressed and the TOR kinase is activated, which stimulates anabolic reactions and growth. The role of competing SnRK1 and TOR kinases as the main regulators of such a process is considered, along with the function of signals mediated by trehalose-6-phosphate highly similar to the TOR signalling pathway. All these regulatory mechanisms enable plants to adapt to environmental changes and maintain homeostasis. It is possible that additional information will be obtained in the nearest future on the interaction of energy and stress-dependent signals in plants through the antagonism of TOR and SnRK1.

In Vitro Digestion and Fermentation by Human Fecal Microbiota of Polysaccharides from Flaxseed.

The digestion of flaxseed polysaccharides (FSP) in simulated saliva, gastric and small intestine conditions was assessed, as well as in vitro fermentation of FSP by human gut microbiota. FSP was not degraded in the simulated digestive systems (there was no change in molecular weight or content of reducing sugars), indicating that ingested FSP would reach the large intestine intact. Changes in carbohydrate content, reducing sugars and culture pH suggested that FSP could be broken down and used by gut microbiota. FSP modulated the composition and structure of the gut microbiota by altering the Firmicutes/Bacteroidetes ratio and increasing the relative abundances of Prevotella, Phascolarctobacterium, Clostridium and Megamonas, which can degrade polysaccharides. Meanwhile, FSP fermentation increased the concentration of short-chain fatty acids, especially propionic and butyric acids. Our results indicate that FSP might be developed as a functional food that benefits gut health.

Juvenile plants of an epiphytic bromeliad exhibit rapid changes in carbohydrate content and antioxidant capacity to cope with water withholding

Global warming reduces water availability, exposing plants to more pronounced wet/dry cycles during their lifetime. Under these circumstances, epiphytic bromeliads can be more responsive due to their lack of contact with soil and high dependence on atmospheric water, especially in the case of juvenile individuals, which lose water more intensely than conspecific adults. In this study, we hypothesized that juvenile plants of Acanthostachys strobilacea (Schult. & Schult.f.) Klotzsch would exhibit rapid metabolic defense mechanisms to tolerate the leaf water loss caused by short-term water withholding (i.e. mild to moderate stress). We exposed plants to an 8-day water restriction and assessed their enzymatic antioxidant capacity and carbohydrate content. At 4 days of water restriction, A. strobilacea plants showed starch mobilization and increased the soluble carbohydrate content. After 8 days, carbohydrate reserves were depleted and the antioxidant enzyme activity was stimulated. Our results demonstrated that juvenile epiphytic bromeliads exhibit rapid metabolic adjustments to short-term water deficiency, which might be crucial for their survival in the face of the expected intensification of drought.

Sucrose synthase is involved in the carbohydrate metabolism-based regulation of seed dormancy release in Pyrus calleryana Decne

ABSTRACT Seed dormancy is an adaptation key to survival in conditions unsuitable for growth. In pear (Pyrus calleryana Decne), phytohormones participate in the release of seed dormancy. However, the involvement of carbohydrate metabolism in this process is still unclear. In the present study, we determined the sucrose, starch, and glucose levels during seed dormancy release. Sucrose and starch content decreased, whereas glucose levels increased. Consistent with these changes in carbohydrate content, the activity levels of sucrose synthase (SS) and α-amylase increased because they cleavaged sucrose and starch, respectively. In contrast, sucrose phosphate synthase (SPS) activity decreased during seed dormancy release. This latter enzyme catalyzes sucrose synthesis. Seed dormancy release was decreased during stratification in the presence of an antisense oligonucleotides (As-ODN) for PcaSS8. Moreover, sucrose levels increased and the activities of SS and α-amylase decreased during seed dormancy release after the treatment of As-ODN. Taken together, our results suggest that sucrose synthase plays an important role in regulating carbohydrate metabolism during seed dormancy release in P. calleryana.

Changes in carbohydrate content in petal parts of incurved malformed flowers of fragrant cut rose cultivar ‘Yves Piaget’

Changes in carbohydrate content in petal parts of incurved malformed flowers of fragrant cut rose cultivar ‘Yves Piaget’

Winter Embolism and Recovery in the Conifer Shrub Pinus mugo L.

Research Highlights: Pronounced winter embolism and recovery were observed in the Alpine conifer shrub Pinus mugo L. Data indicated that the hydraulic courses and underlying mechanism were similar to timberline trees. Background and Objectives: At high elevation, plants above the snow cover are exposed to frost drought and temperature stress during winter. Previous studies demonstrated winter stress to induce low water potentials (Ψ) and significant xylem embolism (loss of conductivity, or LC) in evergreen conifer trees, and recovery from embolism in late winter. Here, we analyzed xylem hydraulics and related structural and cellular changes in a conifer shrub species. Materials and Methods: The uppermost branches of Pinus mugo shrubs growing at the Alpine timberline were harvested over one year, and the Ψ, water content, LC, proportion of aspirated pits, and carbohydrate contents were analyzed. Results: Minimum Ψ (−1.82 ± 0.04 MPa) and maximum LC (39.9% ± 14.5%) values were observed in mid and late winter, followed by a recovery phase. The proportion of aspirated pits was also highest in winter (64.7% ± 6.9% in earlywood, 27.0% ± 1.4% in latewood), and decreased in parallel with hydraulic recovery in late winter and spring. Glucose and fructose contents gradually decreased over the year, while starch contents (also microscopically visible as starch grains in needle and stem tissues) increased from May to July. Conclusions: The formation and recovery of embolism in Pinus mugo were similar to those of timberline trees, as were the underlying mechanisms, with pit aspiration enabling the isolation of embolized tracheids, and changes in carbohydrate contents indicating adjustments of osmotic driving forces for water re-distribution. The effects of future changes in snow cover regimes may have pronounced and complex effects on shrub-like growth forms, because a reduced snow cover may shorten the duration of frost drought, but expose the plants to increased temperature stress and impair recovery processes.

Changes in Starch Synthesis and Metabolism Within Developing Bulbs of Lycoris radiata During the Vegetative Growth Stage

Lycoris is a genus of plants with flowering bulbs that have high ornamental, medicinal, and ecological value. The slow growth of Lycoris bulbs under natural conditions is a constraint to the Lycoris industry. Thus, accelerating the development of Lycoris bulbs is extremely important. Starch provides the energy and material basis for bulbs to enlarge. Previous studies have shown reduced starch metabolism capacity in Lycoris bulbs when dormant, but changes within bulbs during the vegetative growth stage remain poorly understood. In our present study, four groups of developing Lycoris radiata bulbs during the vegetative growth phase and with the same genetic background were created and used to investigate changes in carbohydrate content, starch synthesis, metabolic enzyme activity, and the gene expression patterns of several genes encoding these enzymes. Increases in enzyme activity during starch synthesis, especially for AGPase, were observed and correlated with the expression levels of the AGPase genes. Starch levels initially increased and then declined. This may be due to the increasing activity of amylase, which resulted in a rapid increase in sugar concentration during bulb development. We also detected changes in starch synthesis and metabolism from different layers of the bulbs during development, with increases in starch synthesis and starch degradation activity being more significant in the middle scales. The sugar within the middle scales may be transported to the inner scales, which increases the inner scale sugar content, promotes the expression levels of CycD genes, and accelerates cell division during bulb development.

Genetic Diversity of Diurnal Carbohydrate Accumulation in White Clover (Trifolium repens L.)

White clover (Trifolium repens L.) is one of the most important legumes for fodder production in temperate climates, particularly in intensive pasture systems. Like many other forage legumes, it lacks the energy content to maximize productivity of modern ruminant livestock breeds. White clover produces water-soluble carbohydrates and starch in its leaves as a diurnal product of photosynthesis. However, little is known about the genetically encoded variability of diel changes in carbohydrate content. We assessed the amount of glucose, fructose, sucrose, and starch in the leaves of 185 plants of a genetically diverse white clover population. Water-soluble carbohydrates only provided on average 10.6% of dry weight (DW) of the total analyzed non-structural carbohydrate (NSC) content at the end of the day (ED), while starch supplied 89.4% of the NSC content. The top 5% of individuals accumulated over 25% of their DW as starch at ED. The leaf starch content at ED showed up to a threefold difference between genotypes, with a repeatability value of 0.95. Our experiments illustrate both the physical potential of white clover to serve as a competitive energy source to meet the demand of modern ruminant livestock production and the genetic potential to improve this trait by breeding.

Events Associated with Early Age-Related Decline in Adventitious Rooting Competence of Eucalyptus globulus Labill.

The development of adventitious roots is affected by several factors, including the age of the cutting donor plant, which negatively affects rooting capacity. Eucalyptus globulus quickly loses rooting capacity of cuttings as the donor plant ages, although the molecular and biochemical mechanisms behind this process are still unclear. To better understand the bases of rooting competence loss in E. globulus, the time required for a significant decline in rhizogenic ability without exogenous auxin was determined in microcuttings derived from donor plants of different ages after sowing. Tip cuttings of donor plants were severed before and after loss of rooting competence of microcuttings to test the hypothesis that auxin and carbohydrate homeostasis regulate rooting competence decline. There were no significant changes in concentration of carbohydrates, flavonoids, or proteins before and after the loss of rooting capacity. Peroxidase (EC 1.11.1.7) total activity increased with loss of rooting competence. Auxin concentration showed the opposite pattern. In good agreement, TAA1, a key gene in auxin biosynthesis, had lower expression after loss of rooting capacity. The same applied to the auxin receptor gene TIR1, suggesting reduced auxin sensitivity. On the other hand, genes associated with auxin response repression (TPL, IAA12) or with the action of cytokinins, the rhizogenesis inhibitor-related ARR1, showed higher expression in plants with lower rooting competence. Taken together, data suggest that age negatively affects E. globulus rooting by a combination of factors. Decreased endogenous auxin concentration, possibly caused by less biosynthesis, lower auxin sensitivity, higher expression of genes inhibiting auxin action, as well as of genes related to the action of cytokinins, appear to play roles in this process.

Seasonal Carbohydrate Changes in the Leaves of Some Satsuma Cultivars on Different Rootstocks

The seasonal changes of carbohydrate content were monitored in the leaves of ‘Okitsu’, ‘Clausellina’, and ‘Silverhill’ satsuma cultivars budded on the sour orange (Citrus aurantium L. var. Yerli), Carrizo and Troyer citranges (Poncirus trifoliata Raf. x Citrus sinensis Osb. var. Troyer and Carrizo) during the 2010 and 2011 seasons. The seasonal changing trends of leaf soluble sugar contents of 3 satsuma cultivars budded on different rootstocks were similar. The sucrose was the most abundant soluble sugar. Carbohydrate contents had a maximum level at dormant period, and remained at low level during summer. In this period, the sharp decrease in leaf total carbohydrate concentration of ‘Okitsu’, ‘Clausellina’ and ‘Silverhill’ occurred in April with a rate of 27.9%, 22.6% and 21.0%, respectively. Accumulation of carbohydrate in leaves generally started after mid summer and continued until the end of year. The rootstocks were found to be not significant for total soluble sugar, starch and total carbohydrate concentration in most of the months. The cultivars had a significant effect on carbohydrate fractions of leaves compared to rootstocks. The scion-rootstock combination was significant on total carbohydrate concentration of leaves in all months investigated.

Endogenous circadian rhythms in pigment composition induce changes in photochemical efficiency in plant canopies

There is increasing evidence that the circadian clock is a significant driver of photosynthesis that becomes apparent when environmental cues are experimentally held constant. We studied whether the composition of photosynthetic pigments is under circadian regulation, and whether pigment oscillations lead to rhythmic changes in photochemical efficiency. To address these questions, we maintained canopies of bean and cotton, after an entrainment phase, under constant (light or darkness) conditions for 30-48 h. Photosynthesis and quantum yield peaked at subjective noon, and non-photochemical quenching peaked at night. These oscillations were not associated with parallel changes in carbohydrate content or xanthophyll cycle activity. We observed robust oscillations of Chl a/b during constant light in both species, and also under constant darkness in bean, peaking when it would have been night during the entrainment (subjective nights). These oscillations could be attributed to the synthesis and/or degradation of trimeric light-harvesting complex II (reflected by the rhythmic changes in Chl a/b), with the antenna size minimal at night and maximal around subjective noon. Considering together the oscillations of pigments and photochemistry, the observed pattern of changes is counterintuitive if we assume that the plant strategy is to avoid photodamage, but consistent with a strategy where non-stressed plants maximize photosynthesis.

Fructan stability in strawberry sorbets in dependence on their source and the period of storage

Many epidemiologic studies have shown a role of diet rich in fruits and vegetables in the prevention of several chronic diseases. Fructans are widely used in functional foods for their health-promoting and technological properties. Strawberry sorbets containing fructans could be an interesting alternative to traditional ice cream. The contents of fructan, glucose, fructose and sucrose were determined to evaluate their changes during storage of strawberry sorbets with three fructan sources: Jerusalem artichoke tubers, yacon root powder and Beneo Orafti Synergy 1. Analyses were performed immediately after product preparation, as well as during 3-month storage at −22 ± 2 °C, in the 2-week intervals. It was observed that the changes of the fructan content were insignificant during the first 2 weeks of storage in all sorbets. The decrease in fructan content was connected with the increase in the amount of glucose, fructose as well as sucrose, independently of fructan source. After 12 weeks of freezing storage, sorbet with Jerusalem artichoke tubers was characterized by the highest stability of fructans, as compared to the other products. The knowledge about the changes of carbohydrate content, especially fructans, during storage is crucial from nutritional point of view (to obtain product with the highest content of pro-healthy compounds).

Individualized Responses of Gut Microbiota to Dietary Intervention Modeled in Humanized Mice.

Diet plays an important role in shaping the structure and function of the gut microbiota. The microbes and microbial products in turn can influence various aspects of host physiology. One promising route to affect host function and restore health is by altering the gut microbiome using dietary intervention. The individuality of the microbiome may pose a significant challenge, so we sought to determine how different microbiotas respond to the same dietary intervention in a controlled setting. We modeled gut microbiotas from three healthy donors in germfree mice and defined compositional and functional alteration following a change in dietary microbiota-accessible carbohydrates (MACs). The three gut communities exhibited responses that differed markedly in magnitude and in the composition of microbiota-derived metabolites. Adjustments in community membership did not correspond to the magnitude of changes in the microbial metabolites, highlighting potential challenges in predicting functional responses from compositional data and the need to assess multiple microbiota parameters following dietary interventions. IMPORTANCE Dietary modification has long been used empirically to modify symptoms in inflammatory bowel disease, irritable bowel syndrome, and a diverse group of diseases with gastrointestinal symptoms. There is both anecdotal and scientific evidence to suggest that individuals respond quite differently to similar dietary changes, and the highly individualized nature of the gut microbiota makes it a prime candidate for these differences. To overcome the typical confounding factors of human dietary interventions, here we employ ex-germfree mice colonized by microbiotas of three different humans to test how different microbiotas respond to a defined change in carbohydrate content of diet by measuring changes in microbiota composition and function using marker gene-based next-generation sequencing and metabolomics. Our findings suggest that the same diet has very different effects on each microbiota's membership and function, which may in turn explain interindividual differences in response to a dietary ingredient.

Effect of CPPU on Carbohydrate and Endogenous Hormone Levels in Young Macadamia Fruit.

N-(2-Chloro-4-pyridyl)-N′-phenylurea (CPPU) is a highly active cytokinin-like plant growth regulator that promotes chlorophyll biosynthesis, cell division, and cell expansion. It also increases fruit set and accelerates fruit enlargement. However, there has been no report about the effect of CPPU on fruit development and its physiological mechanism in macadamia. In this study, we investigated the effect of CPPU treatment at early fruit development via foliar spray or raceme soaking at 20 mg·L-1 on fruit set and related physiology in macadamia. Changes in carbohydrate contents and endogenous hormones in leaves, bearing shoots and fruit were also examined. Results showed that CPPU significantly reduced young fruit drop and delayed the wave of fruit drop by 1–2 weeks. The treatment significantly decreased the contents of total soluble sugars and starch in the leaves, but increased them in the bearing shoots and total soluble sugars in the husk (pericarp) and seeds. These findings suggested that CPPU promoted carbohydrate mobilization from the leaves to the fruit. In addition, CPPU increased the contents of indole-3-acetic acid (IAA), gibberellin acid (GA3), and zeatin riboside (ZR) and decreased the abscisic acid (ABA) in the husk. Therefore, CPPU treatment reduced the early fruit drop by increasing carbohydrate availability and by modifying the balance among endogenous hormones.