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Periods of high nighttime temperature may induce carbohydrate (CH) shortage by increased dark respiration. Metamitron is a thinning agent that inhibits photosynthesis and enhances fruit abscission due to a reduction in CH production. To clarify how both interact in apple tree physiologic mechanisms and on fruit abscission, five field trials were carried out in Lleida, Girona and Sint-Truiden (2017 + 2018), using orchards of ‘Golden’ apple trees. At the stage of 12–14 mm fruit diameter, four treatments were established: (A) CTR – control, trees under natural environmental conditions; (B) HNT – high nighttime temperature, trees exposed to artificially increased nighttime temperature during 5 nights after the day of spraying, without metamitron application; (C) MET - 247.5 ppm of metamitron application and (D) MET + HNT - trees submitted to the combined exposure to metamitron application (MET) and to artificially increased nighttime temperature (HNT). HNT did not affect metamitron absorption, net photosynthesis (Pn) and stomatal conductance however, promoted significant reductions in leaf CH content mainly before sunrise, especially in sucrose (18–45%) and in sorbitol (19–26%). Metamitron significantly reduced Pn to about 50% of CTR, which resulted in decreases in leaf sucrose and sorbitol, reaching minimum values 5 days after spraying, between 21 and 57% and 19–26%, respectively. Fruit growth rate of both treatments was retarded by 30%, 2 days after either metamitron application or HNT. Both treatments originated a similar reduction in the number of fruits and size improvement. The combined exposure (MET+HNT) promoted similar Pn reductions as MET, but showed the greatest sucrose (44–60%) and sorbitol (73–84%) decreases which resulted in the strongest thinning efficacy. Lipid peroxidation was not affected by the treatments however, antioxidant enzyme activity showed moderate changes with activity increases mainly under MET and MET + HNT, accompanied by a rise in glutathione content and reduction in ascorbate. This work shows that the overlap of photosynthesis inhibition (reducing CH production) by means of metamitron spraying, and likely greater respiration (increased CH consumption), by HNT imposition, translates less CH production than the growing fruits demand (negative CH balance) leading to a metamitron thinning effect enhancement. Periods of high nighttime temperature must be considered when deciding the best metamitron rate to achieve an optimal crop load result. info:eu-repo/semantics/acceptedVersion

Thinning strategies, namely shade or photosynthetic inhibitors, rely on the reduction of carbon supply to the fruit below the demand, causing fruit abscission. In order to clarify the subject, seven field trials were carried out in Lleida, Girona, and Sint-Truiden (2017 + 2018), using orchards of &lsquo, Golden&rsquo, and &lsquo, Gala&rsquo, apple trees. At the stage of 9&ndash, 14-mm fruit diameter, four treatments were implemented: (A) CTR-control, trees under natural environmental conditions, (B) SN&ndash, shaded trees, trees above which shading nets reducing 50% of irradiance were installed 24 h after metamitron application date&mdash, without application of metamitron&mdash, and removed after five days, (C) MET-trees sprayed with 247.5 ppm of metamitron, (D) MET + SN&ndash, trees submitted to the combined exposure to metamitron application and shading nets. Low radiation significantly increased metamitron absorption (36&ndash, 53% in the three locations in 2018) and reduced its degradation. Net photosynthesis and stomatal conductance were strongly reduced in all treatments, with minimum values 2 days after spraying (DAS) and incomplete recovery 10 DAS in MET + SN. All treatments resulted in leaf sucrose and sorbitol decreases, leading to a negative carbon balance. SN and MET + SN promoted the highest thinning efficacy, increasing fruit weight and size, with MET + SN causing over-thinning in some trials. Leaf antioxidant enzymes showed moderate changes in activity increases under MET or MET + SN, accompanied by a rise of glutathione content and a reduction in ascorbate, however without lipid peroxidation. This work shows that environmental conditions, such as cloudy days, must be carefully considered upon metamitron application, since the low irradiance enhances metamitron efficacy and may cause over-thinning.

Northwestern Iberia is characterized for being an Atlantic/Mediterranean transitional area, where the most natural forests contain certain species, typical from either biogeographic region, growing under limiting conditions due to their marginal location. In order to identify the main climatic factors controlling growth, and thus better understand how they impact wood formation processes of the key tree species in these ecosystems, we analyzed tree rings of two somehow contrasting oaks (Quercus robur, Atlantic; and Q. pyrenaica, sub-Mediterranean) at their distribution boundary towards the Mediterranean region. For this, two nearby sites with slightly different regime of water availability were selected for each species. We developed chronologies of radial increment (expressed as latewood width) and functional anatomical traits (size and number of earlywood vessels) for the last decades, and also monitored wood formation along two growing seasons. Our results suggest that the combination of anatomical traits and radial growth constitute a useful tool to understand the behavior of these species in boundary distribution areas. We found some differences between sites, especially for Q. pyrenaica, but the main factors controlling growth were clearly identified at all sites. Earlywood characteristics were mainly related to temperature, whereas latewood width responded to precipitation, regardless of the species. However, vessels of low-elevation Q. robur seemed to be controlled by factors affecting carbohydrate balance, while those of high-elevation Q. pyrenaica were associated to spring conditions for growth resumption. Summer water availability was linked to a wider latewood for both species. In addition, the analysis of xylogenesis carried out at all sites was essential to interpret climate responses by providing evidences for the existence of a cause-effect relationship.

Metamitron is an apple (Malus domestica Borkh.) fruit thinner that acts by reducing the photosynthetic capacity of trees. Relative humidity may influence thinning efficacy, however, the broadness of this effect is not yet fully understood. Trials were set in Sint-Truiden (Belgium) in 2018 and Lleida and Girona (Spain) in 2019, using 4-year-old cvs. Braeburn and Elstar trees in Belgium, and 16-year-old cv. Golden Reinders trees in Spain. Four treatments were implemented at the stage of 12&ndash, 14 mm fruit diameter: (a) CTR&mdash, control, trees under natural environmental conditions, (b) HH&mdash, high humidity, trees submitted to artificially increased air relative humidity applied for 3 h prior to the beginning of the experiment, (c) MET&mdash, trees sprayed with 247.5 mg/L metamitron, (d) MET + HH&mdash, trees submitted to the combination of increased humidity (HH) and metamitron (MET) application. In Belgium, metamitron absorption by leaves was greater than in Spain. This might be related to morphological characteristics of the leaves which developed under greater natural relative humidity levels in Belgium than in Spain. Compared to MET alone, &lsquo, Braeburn&rsquo, and &lsquo, Elstar&rsquo, demonstrated significantly greater metamitron absorption, 59% and 84%, respectively, under MET + HH, accompanied by declines in leaf net photosynthesis (10% and 32%, respectively) and sucrose (31% and 26%, respectively). At harvest, MET + HH treatment reduced yield by 24% and 32% in &lsquo, respectively, when compared with MET alone. A large reduction (considered over thinning) in the yield of &lsquo, occurred. In contrast, metamitron absorption by &lsquo, Golden Reinders&rsquo, using MET alone was similar to MET + HH, however, there was a slight foliar sugar reduction in the latter treatment. In addition, both treatments enhanced shoot growth and increased fruit abscission with similar improvements in fruit weight and size. In this study, high relative humidity enhanced fruit thinning efficacy under certain circumstances, such as age or genetic predisposal, which left the tree more susceptible to a negative carbohydrate balance. For instance, &lsquo, were easier to thin when compared to &lsquo, In addition, this study raises a question that requires further research regarding the impact of HH before and after spraying as well as its effect in combination with higher temperatures.

Ingesting nutritionally imbalanced food can cause a significant reduction in fitness in insects. Insects can avoid the negative consequences of nutritional imbalances by selectively foraging for nutritionally complementary foods. We investigated the ability of the omnivorous beetle, Tenebrio molitor (Coleoptera: Tenebrionidae), to redress nutritional imbalances by selecting complementary foods. Beetles were fed one of three synthetic diets that varied in their protein: carbohydrate balance (p0:c42, p21:c21 or p42:c0) for 16 days and then allowed to select between two nutritionally imbalanced but complementary diets (p0:c42 vs. p42:c0) for 18 days. During the initial period, beetle survival was high on all three experimental diets, but their body composition was considerably skewed as a result of eating nutritionally imbalanced diets. Over the first 6 days of food choice (days 16-22), beetles previously fed a protein-rich, carbohydrate-deficient diet (p42:c0) preferred carbohydrate to protein, whereas those previously fed a carbohydrate-rich, protein-deficient diet (p0:c42) strongly preferred the protein-rich diet. When the food choice period continued for longer than 6 days, the selection of diets by previously carbohydrate-deprived beetles (p42:c0) was similar to that of the control beetles previously fed an optimal food (p21:c21). However, beetles that were previously fed on the protein-deficient diet (p0:c42) selected protein and carbohydrate equally throughout the remaining period of food choice and the cumulative protein-carbohydrate intake of these protein-deprived beetles was similar to that of those fed the optimal diet (p21:c21). At the end of the experiment, the body composition of all beetles was similar, indicating that the effects of nutritional imbalance on body composition were buffered by the subsequent selection of complementary foods. Our results demonstrate that T. molitor beetles are capable of redressing nutritional imbalances and indicate that the way in which the nutritional balance of beetles is restored depends on the nutrient that is initially deficient in their food.

Alterations in energy balance must be accommodated by adjustments in the net storage of the major energy-yielding macronutrients: carbohydrate, protein, and fat. This study used continuous whole-body calorimetry to measure changes in energy expenditure and substrate oxidation during a 12-d imposed energy imbalance in six lean men on mixed diets (overfeeding: 16.5 MJ/d, +33%, n = 3; underfeeding: 3.5 MJ/d, -67%, n = 3). Changes in total energy expenditure (TEE) and its components were modest; TEE changed by +6.2% (overfeeding) and -10.5% (underfeeding). In consequence, body weight changed by +2.90 and -3.18 kg. Marked changes in metabolic fuel selection occurred over the course of the study. Carbohydrate intake (540 and 83 g/d for overfeeding and underfeeding, respectively) exerted direct autoregulatory feedback on carbohydrate oxidation (551 and 106 g/d at day 12 for overfeeding and underfeeding, respectively). Subjects were close to balance by day 5. Changes in protein oxidation were small and not sufficient to prevent the oxidation of body protein mass, or its accretion, in response to energy deficit or surplus. Fat oxidation (59 and 177 g/d for overfeeding and underfeeding, respectively) was not sensitive to dietary fat intake (150 and 20 g/d, for overfeeding and underfeeding, respectively), rather, its oxidation was inversely related to the oxidation of other substrates. Changes in fat balance accounted for 74.1% and 84.0% of the energy imbalance during overfeeding and underfeeding, respectively. This study shows a clear oxidative hierarchy for the macronutrients. Metabolic fuel selection is dominated by the need to maintain carbohydrate balance. This induces inappropriate counterregulatory alterations in fat oxidation during energy surplus.

In order to examine the effect of plant age on asparagus yielding, the number and weight of spears were analyzed. The experiment was carried out on 1-, 4- and 7-year-old plants in the aeroponic system with recirculation. The results showed that the spear number and thus also the yield were not plant age dependent, while spear diameter and their weight were. Taking into account both crown weight and the age of plants, a 26% variation in spear diameter and a 27% variation in mean spear weight were explained. Determination of dry weight and carbohydrate contents in storage roots showed these traits to be independent of asparagus plant age, except for total carbohydrate content per plant. During harvest dry weight, % Brix, sucrose, fructan and total carbohydrates contents losses were also recorded.

Background As part of the growing lifestyle diversity in modern society, there is wide variation in the time of day individuals choose to exercise. Recent surveys in the US and Japan have reported that on weekdays, more people exercise in the evening, with fewer individuals exercising in the morning or afternoon. Exercise performed in the post-prandial state has little effect on accumulated fat oxidation over 24 h (24-h fat oxidation) when energy intake is matched to energy expenditure (energy-balanced condition). The present study explored the possibility that exercise increases 24-h fat oxidation only when performed in a post-absorptive state, i.e. before breakfast. Methods Indirect calorimetry using a metabolic chamber was performed in 10 young, non-obese men over 24 h. Subjects remained sedentary (control) or performed 60-min exercise before breakfast (morning), after lunch (afternoon), or after dinner (evening) at 50% of VO2max. All trials were designed to be energy balanced over 24 h. Time course of energy and substrate balance relative to the start of calorimetry were estimated from the differences between input (meal consumption) and output (oxidation). Findings Fat oxidation over 24 h was increased only when exercise was performed before breakfast (control, 456 ± 61; morning, 717 ± 64; afternoon, 446 ± 57; and evening, 432 ± 44 kcal/day). Fat oxidation over 24 h was negatively correlated with the magnitude of the transient deficit in energy and carbohydrate. Interpretation Under energy-balanced conditions, 24-h fat oxidation was increased by exercise only when performed before breakfast. Transient carbohydrate deficits, i.e., glycogen depletion, observed after morning exercise may have contributed to increased 24-h fat oxidation., Highlights • Exercise performed before breakfast increases 24 h fat oxidation. • Exercise-induced transient energy deficit cues to increase 24 h fat oxidation. • Exercise in fed state doesn't increase 24 h fat oxidation in energy-balanced condition. • Urinary N2 excretion was not affected by time of the day when exercise was performed. Indirect calorimetry using a metabolic chamber was performed in 10 young men over 24 h. Subjects remained sedentary or performed 60-min exercise before breakfast, after lunch or dinner at 50% of VO2max. All trials were designed to be energy balanced, i.e., intake and expenditure of energy over 24-h were matched. When exercise was performed after lunch or dinner, 24-h fat oxidation was similar to that of sedentary day, i.e. exercise didn't increase fat oxidation. Only when exercise was performed before breakfast, 24-h fat oxidation increased, and a significant transient energy deficit after morning exercise seems to stimulate 24-h fat oxidation.

BACKGROUND: The carnitine O-palmitoyltransferase I (EC 2.3.1.21) inhibitor etomoxir inhibits fatty acid oxidation, and hepatic fatty acid oxidation has been suggested to be a metabolic satiety signal in subjects who consume high-fat diets. OBJECTIVE: We investigated substrate oxidation and satiety after repeated administrations of etomoxir or placebo in subjects who consumed a high-fat diet. DESIGN: In a randomized crossover design consisting of three 5-d treatments, we fed 10 healthy men [mean +/- SE age: 25.6 +/- 1.7 y; mean +/- SE body mass index (in kg/m(2)): 21.8 +/- 0.3] a high-fat diet twice and a low-fat diet once. The subjects consumed each diet at home for 3 consecutive days, after which they spent 36 h in energy balance in a respiration chamber. During the chamber stays with the high-fat treatments, etomoxir or placebo was administered in 5 doses (600 mg etomoxir in total). Blood samples were obtained on the mornings of days 4 and 5 of each treatment, and appetite profiles were assessed. RESULTS: Mean (+/-SE) 24-h respiratory quotients were significantly (P < 0.05) higher with repeated administrations of etomoxir (0.833 +/- 0.004) than with repeated administrations of placebo (0.814 +/- 0.006), and mean (+/-SE) 24-h whole-body fat oxidation tended to be less (13.7%, P = 0.06) with administration of etomoxir (136.0 +/- 5.2 g/d) than with administration of placebo (157.5 +/- 5.6 g/d). With the etomoxir treatment, fat balance was positive (P < 0.0001) and carbohydrate balance was negative (P < 0.001), whereas with the placebo treatment, neither of the balances was significantly different from zero. Hunger and satiety ratings were not affected under these conditions. CONCLUSIONS: Etomoxir decreased whole-body fat oxidation, as indicated by the respiratory quotients in the healthy subjects. With the current protocol, however, hunger and satiety ratings were not affected.

Background: While compensatory eating following acute aerobic exercise is highly variable, little is known about the underlying mechanisms that contribute to the alterations in exercise-induced eating behaviour. \ud \ud Methods: Overweight and obese women (body mass index=29.6±4.0 kg/m2) performed a bout of cycling individually tailored to expend 400 kcal (EX) or a time-matched no exercise control condition in a randomised, counter-balanced order. 60 min after the cessation of exercise, an ad libitum test meal was provided. Substrate oxidation and subjective appetite ratings were measured during exercise/time-matched rest, and during the period between the cessation of exercise and food consumption.\ud \ud Results: While ad libitum energy intake (EI) did not differ between EX and the control condition (666.0±203.9 vs 664.6±174.4 kcal, respectively; ns), there was a marked individual variability in compensatory EI. The difference in EI between EX and the control condition ranged from −234.3 to 278.5 kcal. Carbohydrate oxidation during exercise was positively associated with postexercise EI, accounting for 37% of the variance in EI (r=0.57; p=0.02). \ud \ud Conclusions: These data indicate that the capacity of acute exercise to create a short-term energy deficit in overweight and obese women is highly variable. Furthermore, exercise-induced CHO oxidation can explain a part of the variability in acute exercise-induced compensatory eating. Postexercise compensatory eating could serve as an adaptive response to facilitate the restoration of carbohydrate balance.

Whole-body thermogenesis, substrate utilization (open-circuit ventilated-hood system), and exogenous carbohydrate oxidation were evaluated in 10 healthy lean male volunteers (aged 27.8 -+ 2.5 years) for 6 hours after oral ingestion of 75 g naturally enriched fructose, glucose (both derived from corn starch), cane sugar, and a good digestible corn starch {all mixed with 400 mL water). The integrated areas under the glucose and insulin response curves above baseline were highest with glucose and starch, intermediate with sucrose, and lowest with fructose, whereas there were no significant differences in the integrated nonesterified fatty acid (NEFA) response between carbohydrates. The total increment in energy expenditure (EE) above baseline was similar with fructose (130 -+ 24 k J/6 h) and sucrose (141 _+ 17 k J/6 h), was higher with sucrose as compared with starch (108 -+ 24 kJ / 6 h, P < .05) and glucose (94 +- 20 kJ ! 6 h, P < .05), and tended to be higher with fructose as compared with glucose (P = .059). Both the increment in total carbohydrate oxidation (P < .05) and the increment in exogenous carbohydrate oxidation (P < .01) were significantly higher with fructose and sucrose compared with glucose and starch. The initial inhibition of lipid oxidation was higher with sucrose and fructose than with glucose and starch, whereas the integrated decrement in lipid oxidation over 6 hours was only higher with fructose compared with glucose and starch (P < .05). In conclusion, thermogenesis and substrate utilization vary considerably after ingestion of different types of carbohydrate in young lean males, indicating that the carbohydrate composition of the diet may have important consequences for energy and macronutrient balance. Copyright © 1996 by W.B. Saunders Company T HERE IS INCREASING evidence that the macronutrient composition of the diet, particularly carbohydrates and fats, plays an important role in the maintenance of energy balance and thus in the regulation of body weight, 1,2 since the body has a limited capacity to regulate fat balance as compared with carbohydrate balance. The body's glycogen stores are relatively small, and (evolutionally) mechanisms have developed to efficiently adjust carbohydrate intake to oxidation. In contrast, fat intake has little effect on fat oxidation, 3 and it has been suggested that the body's carbohydrate economy is a more important determinant of fat oxidation than fat intake. 2 Adjustment of fat oxidation to fat intake may occur over time, since a positive fat balance over a longer period leads to increased fat storage, which can subsequently alter insulin sensitivity, circulating free fatty acid levels, and thus fat oxidation. In the debate on the role of carbohydrate and fat metabolism in body weight maintenance, little attention has been given to the type of carbohydrate. Wide variations exist in absorption rates of carbohydrates, which may be responsible for variations in postprandial glycemic and insulinemic responses. 4 These differences in postprandial hormonal and nutrient profiles may affect the rate of glucose disposal in the cell (oxidation or synthesis), the rate of fat oxidation, and the magnitude of thermogenic response, and may consequently be significant for daily energy and substrate balance. Previous studies have reported different thermogenic effects after ingestion of several dietary carbohydrates. Postprandial thermogenesis is higher after fructose 5-7 or sucrose 8 as compared with glucose ingestion. Additionally, after fructose intake, a higher increase in carbohydrate oxidation and a more pronounced suppression of lipid oxidation have been reported. 5-v Furthermore, the carbohydrate to fat oxidation ratio has been reported to be higher after ingestion of cooked manioc starch (16% amylose) than after ingestion of glucose? So far, no data are available that systematically compare the effects of more than two types of carbohydrates on postprandial thermogenesis and substrate utilization. The present study was therefore intended to investigate the impact of glucose, fructose, sucrose, and starch on postprandial glucose and insulin responses, energy expenditure (EE), and postprandial substrate utilization in young lean male volunteers. All carbohydrates were derived from naturally ~3C-enriched plants, which made it possible to determine the amount of ingested carbohydrate that was directly oxidized (exogenous carbohydrate oxidation) from 13CO2 enrichment in expired air.

To investigate the relationship between postprandial nutrient balance, satiety and hormone changes induced by two different meals taken after a moderate intensity exercise bout. Ten prepubertal obese children participated in the study. The experiment was designed as a cross-over study for repeated measures. Each test period lasted five consecutive hours during which the children were under medical supervision. The effects of two isocaloric meals were compared after a moderate intensity exercise (4 multiples of resting metabolic rate, 30 min, cycling): a low-fat/high-carbohydrate meal (meal A) and a high-fat/low-carbohydrate meal (meal B). Pre and postprandial (3 h) substrate oxidation, biochemical parameters, gastrointestinal hormone concentrations and appetite were measured. The main results were: (i) higher fat balance (5.1±5.0 vs −5.0±6.6 g, P=0.001) and lower carbohydrate balance after meal B than A (−9.7±13.3 vs 11.3±18.3 g, P

Background Many of the metabolic effects of exercise are due to the most recent exercise session. With recent advances in nuclear magnetic resonance spectroscopy (NMRS), it is possible to gain insight about which lipoprotein particles are responsible for mediating exercise effects. Methods Using a randomized cross-over design, very low density lipoprotein (VLDL) responses were evaluated in eight men on the morning after i) an inactive control trial (CON), ii) exercising vigorously on the prior evening for 100 min followed by fasting overnight to maintain an energy and carbohydrate deficit (EX-DEF), and iii) after the same exercise session followed by carbohydrate intake to restore muscle glycogen and carbohydrate balance (EX-BAL). Results The intermediate, low and high density lipoprotein particle concentrations did not differ between trials. Fasting triglyceride (TG) determined biochemically, and mean VLDL size were lower in EX-DEF but not in EX-BAL compared to CON, primarily due to a reduction in VLDL-TG in the 70–120 nm (large) particle range. In contrast, VLDL-TG was lower in both EX-DEF and EX-BAL compared to CON in the 43–55 nm (medium) particle range. VLDL-TG in smaller particles (29–43 nm) was unaffected by exercise. Because the majority of VLDL particles were in this smallest size range and resistant to change, total VLDL particle concentration was not different between any of these conditions. Skeletal muscle lipoprotein lipase (LPL) activity was also not different across these 3 trials. However, in CON only, the inter-individual differences in LPL activity were inversely correlated with fasting TG, VLDL-TG, total, large and small VLDL particle concentration and VLDL size, indicating a regulatory role for LPL in the non-exercised state. Conclusions These findings reveal a high level of differential regulation between different sized triglyceride-rich lipoproteins following exercise and feeding, in the absence of changes in LPL activity.

Over the last 60 years, planting densities for apple have increased as improved management systems have been developed. Dwarfing rootstocks have been the key to the dramatic changes in tree size, spacing and early production. The Malling series of dwarfing rootstocks (M.9 and M.26) have been the most important dwarfing rootstocks in the world but are poorly adapted in some areas of the world and they are susceptible to the bacterial disease fire blight and the soil disease complex, apple replant disease which limits their uses in some areas. Rootstock breeding programs in several parts of the world are developing improved rootstocks with resistance to fire blight, and replant disease, and improved cold hardiness and yield efficiency. A second important trend has been the increasing importance of new cultivars. New cultivars have provided opportunities for higher prices until they are over-produced. A new trend is the "variety club" in which variety owners manage the production and marketing of a new unique cultivar to bring higher prices to the growers and variety owners. This has led to many fruit growers being unable to plant or grow some new cultivars. Important rootstock and cultivar genes have been mapped and can be used in marker assisted selection of future rootstock and cultivar selections. Other important improvements in apple culture include the development of pre-formed trees, the development of minimal pruning strategies and limb angle bending which have also contributed to the dramatic changes in early production in the 2nd-5th years after planting. Studies on light interception and distribution have led to improved tree forms with better fruit quality. Simple pruning strategies and labor positioning platform machines have resulted in partial mechanization of pruning which has reduced management costs. Improved plant growth regulators for thinning and the development of a thinning prediction model based on tree carbohydrate balance have improved the ability to produce the optimum fruit size and crop load. Other new plant growth regulators have also allowed control of shoot growth, control of preharvest fruit drop and control of fruit softening in storage after harvest. As we look to the future, there will be continued incremental improvement in our understanding of plant physiology that will lead to continued incremental improvements in orchard management but there is likely to be dramatic changes in orchard production systems through genomics research and genetic engineering. A greater understanding of the genetic control of dwarfing, precocity, rooting, vegetative growth, flowering, fruit growth and disease resistance which will lead to new varieties and rootstocks which are less expensive to grow and manage.

In mature almond (Prunus dulcis) orchards, the majority of crop is borne on spurs (short, proleptic shoots) that can live for several years and can produce from one to five fruits. Previous research has led to the hypothesis that spur longevity is related to spur light exposure, cropping and age. However, limited quantitative data are available to substantiate these hypotheses. The objective of this study was to determine spur characteristics that were most highly correlated with spur productivity and longevity in mature, bearing almond trees. Previous year spur leaf area was strongly related to spur viability and flowering; the greater the leaf area in the previous year, the higher the probability of spur survival into the next year and the higher the probability for the spur to bear one or more flowers. Previous year bearing also appeared to influence viability and return bloom, especially in spurs with low leaf area. These results suggest that spur source–sink balance is basic to the life cycle of almond spurs. Furthermore, the results are consistent with the hypothesis that spurs are semi-autonomous organs with respect to carbohydrate balance for much of the growing season. Finally, this information provides general thresholds for maintaining spur viability and productivity that will be useful for developing and evaluating tree training systems and orchard management practices.

Energy homeostasis is critical for the survival of species. Therefore, multiple and complex mechanisms have evolved to regulate energy intake and expenditure to maintain body weight. For weight maintenance, not only does energy intake have to match energy expenditure, but also macronutrient intake must balance macronutrient oxidation. However, this equilibrium seems to be particularly difficult to achieve in individuals with low fat oxidation, low energy expenditure, low sympathetic activity or low levels of spontaneous physical activity, as in addition to excess energy intake, all of these factors explain the tendency of some people to gain weight. Additionally, large variability in weight change is observed when energy surplus is imposed experimentally or spontaneously. Clearly, the data suggest a strong genetic influence on body weight regulation implying a normal physiology in an ‘obesogenic’ environment. In this study, we also review evidence that carbohydrate balance may represent the potential signal that regulates energy homeostasis by impacting energy intake and body weight. Because of the small storage capacity for carbohydrate and its importance for metabolism in many tissues and organs, carbohydrate balance must be maintained at a given level. This drive for balance may in turn cause increased energy intake when consuming a diet high in fat and low in carbohydrate. If sustained over time, such an increase in energy intake cannot be detected by available methods, but may cause meaningful increases in body weight. The concept of metabolic flexibility and its impact on body weight regulation is also presented.

SUMMARY Net photosynthesis, dark respiration, chlorophyll and carbohydrate content, and leaf growth in plants of deciduous peach (Prunus persica (L.) Batsch.) and evergreen olive (Olea europaea L.) grown in controlled environmental conditions were measured to assess changes in carbon balance during leaf development at the 6th, 12th and 16th nodes (first flush) from the beginning of expansion to full maturity. A simulation model was written including growth traits, physiological measurements and meteorological data. In both species, gas exchange varied with the percentage of leaf expansion, regardless of the node examined. The relationships between net daily CO2 assimilation (24 h), chlorophyll content, and the ratio of leaf mass per area, across all nodes, differed between species. Photosynthetic capacity differed significantly between different degrees of leaf expansion in both species. The model predicted differences in leaf carbohydrate balance between peach and olive. The onset of carbohydrate export from individual leaves varied with species, being 18 ‐ 19 d and 28 ‐ 29 d from emergence in peach and olive, respectively.

The proinflammatory response of macrophages to stimuli, such as lipopolysaccharide (LPS) or IFNγ, can be blocked by ligands for peroxisome proliferator-activated receptors (PPARs). However, the mechanisms, and even the validity, of this antiinflammatory role for PPARs has recently come under question. The paper by Welch et al. (1) in this issue of PNAS addresses some of these concerns, and suggests that the proposed antiinflammatory effects may result from activation of at least two members of this family of molecules. PPARs represent a subgroup of the nuclear receptor superfamily that contributes to lipid and carbohydrate balance, and hence, homeostatic regulation of energy supplies. They appear to act as lipid sensors and to regulate transcription of lipid metabolizing enzymes, many within the peroxisome (hence their imposing name). The three subtypes of PPAR (α, β or δ, and γ) have different tissue distribution, different (though overlapping) ligand specificity, and mediate their effects by regulating different patterns of gene expression. PPARα is found mainly in heart, liver, and kidney, i.e., tissues with high rates of lipid oxidation, regulates fatty acid catabolism, and has been suggested to act as a “lipostat” to match lipid delivery to oxidative capacity. PPARδ is ubiquitously expressed, but is the least well understood of the group, in terms of either ligands or target genes. By contrast, PPARγ is found (and can be up-regulated) in many cell types, but particularly in adipocytes and macrophages. By appropriate induction of gene expression as well as cooperitivity with other nuclear receptors, PPARγ has been suggested to play a key role in adipose tissue development and cholesterol import and export (2). It can be activated by thiazolidinedione (TZD) drugs (e.g., rosiglitazone), which are used to improve insulin sensitivity in diabetic patients. In addition, over the last 5 years, an antiinflammatory effect has been ascribed to …

The purpose of the present study was to investigate the interrelationship between carbohydrate and fat metabolism at rest after isoenergetic meals of varying proportions of carbohydrate and fat. Eight physically-active subjects (BMI 18·1–23·4 kg/m2) were studied at rest on three occasions after an overnight fast. In a balanced design they were given meals containing carbohydrate, protein and fat in the following amounts respectively (g/70 kg body weight): meal 1 121,16,48; meal 2 70,16,70; meal 3 50, 14, 80. All meals were isoenergetic, containing 4·0 MJ/70 kg body weight, and were of similar appearance. In addition, on a fourth occasion five of the eight subjects consumed meal 4 (g/70 kg body weight): Carbohydrate 0, protein 0, fat 108. Blood samples were taken before eating the meal and at intervals following the meal to determine metabolic and hormonal responses. Energy expenditure and substrate oxidation were measured by indirect calorimetry and balance was calculated over the 5 h postprandial period. The incremental areas under the time curves for fat oxidation were greatest after meals 3 and 4 (P

Urinary nitrogen excretion over a 17 hour period without food and water was determined for mice poisoned with endotoxin and for control mice with and without the subcutaneous injection of 5 mg. cortisone acetate. Endotoxin did not alter the quantity of nitrogen excreted, compared with that of control mice, but in both groups of animals cortisone increased urinary nitrogen by the same amount. A balance between the quantity of protein catabolized (as estimated by increased urinary nitrogen excretion) and the total carbohydrate stored as a result of cortisone administration was found in fasted and in fed mice but not in endotoxin-poisoned mice. Endotoxin inhibited the motility of the gastrointestinal tract and blocked the absorption of food. Injections of ACTH in normal mice increased protein degradation and carbohydrate synthesis. In endotoxin-poisoned animals, ACTH failed to alter urinary nitrogen excretion and carbohydrate reserves. ACTH increased susceptibility to endotoxin. The number of heat-killed cells of S. typhimurium required to block the increase in urinary nitrogen caused by an injection of ACTH was found to be 108. A partial block was found with 5 x 107 cells but not with 105 cells. Mice infected with S. typhimurium excreted less than the normal amount of urinary nitrogen in response to ACTH 6 to 23 hours postinfection while normal amounts of nitrogen were eliminated 54 to 71 hours postinfection. The number of viable cells in the mice during the earlier period was less than the number of dead cells required to alter the nitrogen output, while the reverse was true during the later period.

The liver is generally recognized as the major, if not the sole source of glucose to the body in the postabsorptive state. Estimation of the amount of glucose produced by the liver has been difficult until recent years because of the problem of meas- uring hepatic blood flow and of obtaining the proper bloods for calculation of the arterial- hepatic venous and arterial-portal venous glu- cose differences. Soskin and coworkers (1), how- ever, did make estimates of the hepatic glucose balance in extensively operated dogs. The recent introduction of the procedure of catheterization of the hepatic veins of man (2) has allowed estima- tion of the hepatic blood flow (3, 4) and the col- lection of blood samples from those veins for the determination of the glucose difference between hepatic venous and arterial bloods. This tech- nique has been used by Bondy (5, 6) and ourselves (7) in the study of hepatic carbohydrate balance in normal and diabetic subjects. The product of the arterial-hepatic venous glu- cose difference and the hepatic blood flow pro- vides the splanchnic glucose production. The splanchnic area as used in this paper constitutes the liver plus the various viscera drained by the portal vein. The splanchnic blood flow is equal to the total hepatic blood flow in the absence of sig- nificant portal venous collaterals. The hepatic glucose output, however, exceeds the splanchnic glucose output, as calculated from the hepatic blood flow and the arterial-hepatic venous glucose difference, since the liver must make up for what- ever glucose is consumed by the various portal viscera. The net splanchnic glucose output is thus defined as the hepatic glucose output minus the glucose consumption of the organs drained by the portal vein. The liver itself may be utilizing

Two grades of recycled wood (Waste Wood A and Waste Wood B) were fractionated on a pilot scale (800 BD kg) to monomeric sugars, lignin and lignosulfonates using SO2-Ethanol-Water (AVAP®) technology, including pretreatment, separation of cellulosic and hemicellulosic streams, and saccharification. Carbohydrate mass balance was obtained through determination of poly-, oligo- and monosaccharides as well as sugar degradation products in process streams. High monosaccharide yields were obtained confirming laboratory scale findings. Fermentability of mixed cellulosic and hemicellulosic sugar stream was confirmed on bench scale (25 kg).