Higher Metabolic Efficiency Research Articles

Divergent Response of Two Bark Beetle-Fungal Symbiotic Systems to Host Monoterpenes Reflects Niche Partitioning Strategies.

The successful establishment of bark beetle-fungus symbionts on plants is required to overcome host defenses. However, little is known about how different bark beetle-fungus symbionts adapt to different niches on the same host plant. Here, we investigated the niche partitioning mechanism of two co-occurring bark beetle-fungus symbiotic systems, Ips nitidus-Ophiostoma bicolor and Dendroctonus micans-Endoconidiophora laricicola, on Qinghai spruce (Picea crassifolia) tree. The lower niche of the spruce trunk inhabited by D. micans showed a higher content of monoterpenes than the upper niche of the trunk inhabited by I. nitidus. Dendroctonus micans showed greater tolerance and higher metabolic efficiency toward monoterpenes than I. nitidus. However, both beetle species showed a similar metabolic profile toward α-pinene, albeit with different levels of metabolites. Additionally, O. bicolor, transmitted by I. nitidus, showed a significantly higher tolerance to monoterpenes and pathogenicity to spruce trees than E. laricicola, transmitted by D. micans. In particular, monoterpenoid metabolites were observed to attenuate the inhibitory effect of high-dose α-pinene on E. laricicola, thus increasing its fitness in a high-dose monoterpene microhabitat. These results show that these two bark beetle-fungus symbionts have adapted to different niches, leading to fitness differences in niche distribution that are at least partly related to the different distribution of monoterpene concentration in the spruce trunk. This research provides a novel perspective for understanding the coevolution between bark beetle-fungus symbionts and their host plants.

A metabolic perspective on polyploid invasion and the emergence of life histories: Insights from a mechanistic model.

Whole-genome duplication (WGD, polyploidization) has been identified as a driver of genetic and phenotypic novelty, having pervasive consequences for the evolution of lineages. While polyploids are widespread, especially among plants, the long-term establishment of polyploids is exceedingly rare. Genome doubling commonly results in increased cell sizes and metabolic expenses, which may be sufficient to modulate polyploid establishment in environments where their diploid ancestors thrive. We developed a mechanistic simulation model of photosynthetic individuals to test whether changes in size and metabolic efficiency allow autopolyploids to coexist with, or even invade, ancestral diploid populations. Central to the model is metabolic efficiency, which determines how energy obtained from size-dependent photosynthetic production is allocated to basal metabolism as opposed to somatic and reproductive growth. We expected neopolyploids to establish successfully if they have equal or higher metabolic efficiency as diploids or to adapt their life history to offset metabolic inefficiency. Polyploid invasion was observed across a wide range of metabolic efficiency differences between polyploids and diploids. Polyploids became established in diploid populations even when they had a lower metabolic efficiency, which was facilitated by recurrent formation. Competition for nutrients is a major driver of population dynamics in this model. Perenniality did not qualitatively affect the relative metabolic efficiency from which tetraploids tended to establish. Feedback between size-dependent metabolism and energy allocation generated size and age differences between plants with different ploidies. We demonstrated that even small changes in metabolic efficiency are sufficient for the establishment of polyploids.

Rural system sustainability evaluation based on emergy analysis: An empirical study of 321 villages in China

The deterioration of the rural ecosystem, the poverty of population, and the low well-being of farmers have brought great challenges to the realization of the Sustainable Development Goals (SDGs). Assessing the current situation of rural sustainable development and identifying limiting factors are critical to sustainable development of rural areas. This study evaluates rural sustainability of 321 villages in China based on emergy analysis. Then, random forest has been employed to determine the limiting factors of villages with different sustainable development levels. The results show that the current level of sustainable development in Chinese rural areas is relatively low (from 0.0040 to 9.5468), showing the trend of gradual increase in rural sustainability from the east to the west. There is a trade-off relationship between social-economic development and the ecological environment, resulting from only 32% of villages are high Emergy Yield Rate and low Environmental Loading Ratio. High-sustainability villages are rich in natural resources and higher metabolic efficiency but poor in people's living, indicating that the natural capital needs to be excavated to improve economic levels and social well-being in the future. Low-sustainability villages have better human well-being due to faster economic development, but unbalanced external inputs and outputs result in low metabolic efficiency and high environmental pressure. Precipitation, agricultural materials input, and people living consumption are the main driving factors for rural sustainability. It is suggested to introduce effective policies to increase economic measures and human well-being for high-sustainability villages, and appropriately decrease external purchasing such as fertilizer and pesticides for low-sustainability villages to make progress in rural sustainable development and Chinese Rural Revitalization.

The influence of heat shock on the rate of reserves allocated by wheat seeds for germination and growth

We studied the accumulation and consumption of biomass by five-day-old seedlings of various wheat varieties (Triticum aestivum L.) grown from control and exposed to heat shock (HS) seeds. The suppression shoot and roots growth intensified with the temperature, which caused HS. With increasing the temperature (+50°С, +51°С, +52°С și +53°С) of HS, the biomass of the endosperm of the seeds transferred to the seedling, and spent on respiration during seed germination, and seedling growth decreased. Moreover, the effect of HS was more pronounced on the biomass of endosperm substances transferred to the seedling. To increase the resolution of separating wheat varieties according to their resistance to HS, we applied the optimal value (+52°С) of the HS temperature (HSo). The rate of dry matter transferred from the endosperm to the shoot, roots, and spent on respiration, made it possible to rank various wheat varieties following their resistance to high temperatures. The higher the resistance of a wheat cultivar to high temperatures, the higher the proportion of endosperm substances consumed by exposed to HSo seeds for seedling growth and respiration. With increasing the wheat varieties to high temperatures, the rate of endosperm biomass transferred to the seedling also increased, at the same time that spent on respiration on the contrary, decreased. After exposure to HSo, the seeds of the resistant to high temperatures varieties also showed higher metabolic efficiency than those of less resistant varieties. All parameters characterizing the resistance of leaves and roots to HS suggested that the high-temperature resistance of roots is lower than that of leaves. The method for determining the resistance of wheat varieties to high temperatures, based on the ability of seeds exposed to HSo, to mobilize reserve substances for germination and growth is fast, characterized by increased resolution, and ensures the distribution of wheat varieties according to their resistance to high temperatures.

Multivariate Tools for Evaluating the Use of Organic Fertilizers on Soil Microbial Properties and Maize Yield

The global demand for protein led to the increase of animal production in the world and, mainly, in Brazil. As a consequence, there was an increase in the amount of waste produced, and the need to seek alternatives for its sustainable use. Microbial indicators and multivariate tools can assist in the proper measurement of the impact of the use of this waste on the soil. This study aimed to: 1) measure the effect of the application of organic fertilizers of animal origin in the no-tillage system on soil microbial attributes and its relationship with maize yield; 2) evaluate the potential of separation/discrimination of the different sources of organic fertilizers based on yield and soil microbial and chemical-physical attributes, using multivariate tools. Treatments consisted of annual application of: poultry manure (PM), liquid swine manure (LSM), poultry manure compost (PMC), swine manure compost (SMC), cattle manure compost (CMC) and control (C), without fertilization. Organic fertilizers promoted higher values of microbial biomass (MB) and MBC:TOC ratio in treatments CMC, SMC and PM in the first sampling season (E1), followed by PM, LSM and PMC in the second sampling period (E2). The data show that PM promoted microbial growth in both seasons, with higher metabolic efficiency increasing maize yield by 30% in relation to the treatment with the second highest production, PMC. Multivariate analysis techniques prove to be important tools to study soil quality indicators in systems which use organic fertilizers.

Physiological processes modulate acute and chronic responses to dietary protein/energy ratio fluctuations in individuals and families of Manila clam (Ruditapes philippinarum) selected for variable growth rates

A range of phenotypes differing in growth rate were designed in the Manila clam by combining separate breeding families with size segregation within each family to constitute fast and slow growing groups. Physiological components of the energy budget and scope for growth (SFG) were then compared between these different phenotypes during the acute and chronic responses to two diets that were isocaloric but differed by 3-fold in their protein/energy (P/E) ratios. Both diets were based on the microalgae Rhodomonas lens obtained in either the exponential or the stationary phase of culture. The aims of the study were 1) to test the effects of these changes in food composition on growth rate, estimated as the balance of physiological processes of energy gain and loss integrated in the SFG; and 2) to assess the extent to which physiological adjustments to diet composition are modulated in order to fulfill the variable energy requirements posed by the occurrence of differential growth phenotypes. Growth performance improved with the high-protein (N+) diet for the different family * growth group combinations, with SFG values exceeding by 50% on average the values of the low-protein (N-) diet. Digestive constraints resulted in reduced absorption efficiency with the N-diet, which tended to cancel out the potential benefits of adjusting feeding rates in order to compensate for a low protein ration. Endogenous differences in growth rate associated with segregated phenotypes were mainly accounted for by differences in energy acquisition, with feeding rates differing by ~ 2-fold between fast and slow growers. Additionally, significant differences were recorded for the unitary metabolic costs (i.e., per unit of metabolizable energy), indicating that higher metabolic efficiency was also a component of faster growth.

Utility of the kappa index in the evolution to multiple sclerosis

A range of phenotypes differing in growth rate were designed in the Manila clam by combining separate breeding families with size segregation within each family to constitute fast and slow growing groups. Physiological components of the energy budget and scope for growth (SFG) were then compared between these different phenotypes during the acute and chronic responses to two diets that were isocaloric but differed by 3-fold in their protein/energy (P/E) ratios. Both diets were based on the microalgae Rhodomonas lens obtained in either the exponential or the stationary phase of culture. The aims of the study were 1) to test the effects of these changes in food composition on growth rate, estimated as the balance of physiological processes of energy gain and loss integrated in the SFG; and 2) to assess the extent to which physiological adjustments to diet composition are modulated in order to fulfill the variable energy requirements posed by the occurrence of differential growth phenotypes. Growth performance improved with the high-protein (N+) diet for the different family * growth group combinations, with SFG values exceeding by 50% on average the values of the low-protein (N-) diet. Digestive constraints resulted in reduced absorption efficiency with the N-diet, which tended to cancel out the potential benefits of adjusting feeding rates in order to compensate for a low protein ration. Endogenous differences in growth rate associated with segregated phenotypes were mainly accounted for by differences in energy acquisition, with feeding rates differing by ~ 2-fold between fast and slow growers. Additionally, significant differences were recorded for the unitary metabolic costs (i.e., per unit of metabolizable energy), indicating that higher metabolic efficiency was also a component of faster growth.

Insensitivity of well-conditioned mature sheep to central administration of a leptin receptor antagonist

Ruminants remain productive during the energy insufficiency of late pregnancy or early lactation by evoking metabolic adaptations sparing available energy and nutrients (e.g. higher metabolic efficiency and induction of insulin resistance). A deficit in central leptin signaling triggers these adaptations in rodents but whether it does in ruminants remains unclear. To address this issue, five mature ewes were implanted with intracerebroventricular (ICV) cannula in the third ventricle. They were used in two experiments with an ovine leptin antagonist (OLA) when well-conditioned (average body condition score of 3.7 on a 5 point scale). The first experiment tested the ability of OLA to antagonize leptin under in vivo conditions. Ewes received continuous ICV infusion of artificial cerebrospinal fluid (aCSF), ovine leptin (4 µg/h) or the combination of ovine leptin (4 µg/h) and its mutant version OLA (40 µg/h) for 48 h. Dry matter intake (DMI) was measured every day and blood samples were collected on the last day of infusion. ICV infusion of leptin reduced DMI by 24% (P<0.05), and this effect was completely abolished by OLA co-infusion. A second experiment tested whether a reduction in endogenous leptin signaling in the brain triggers metabolic adaptations. This involved continuous ICV infusions of aCSF or OLA alone (40 µg/h) for 4 consecutive days. The infusion of OLA did not alter voluntary DMI over the treatment period or on any individual day. OLA did not affect plasma variables indicative of insulin action (glucose, non-esterified fatty acids, insulin and the disposition of plasma glucose during an insulin tolerance test) or plasma cortisol, but tended to reduce plasma triiodothyronine and thyroxine (P<0.07). Overall, these data show that a reduction of central leptin signaling has little impact on insulin action in well-conditioned mature sheep. They also raise the possibility that reduced central leptin signaling plays a role in controlling thyroid hormone production.

Mitochondrial Content in Aging Muscle is Associated with Higher Metabolic Efficiency, Fat Oxidation and Insulin Sensitivity

Mitochondrial Content in Aging Muscle is Associated with Higher Metabolic Efficiency, Fat Oxidation and Insulin Sensitivity

The strength of trophic cascades across ecosystems: predictions from allometry and energetics

Summary Top‐down control of trophic structure is often highly variable both within and among ecosystems. We explored the roles of relative body sizes of predators and prey, their metabolic types, the production‐to‐biomass ratio (P : B) of plants, and system productivity in determining the strength of the indirect effects of predators on plants. We used a well‐studied food chain model with three trophic levels that is parameterized based on allometric relationships for rates of ingestion and metabolic efficiency. The model predicts that invertebrate and ectotherm predators and herbivores should propagate cascades to a greater degree than vertebrates and endotherms because of their higher metabolic efficiency. Increasing the herbivore‐to‐plant body‐size ratio strengthened the effects of cascades, while predator body‐size was predicted to have no effect. Increasing system productivity or plant P : B magnified cascades. Because herbivore : plant body size ratios and plant P : B are both generally greater in aquatic than terrestrial systems (especially those with unicellular producers), the model predicts stronger cascades in water than on land. This prediction is supported by a recent cross‐system comparison of trophic cascade experiments. We discuss features of natural systems that are not incorporated into the model and their implications for the intensity of trophic cascades across ecosystems.

Seasonal effects on microorganisms in the rhizosphere of two tropical plants in a polyculture agroforestry system in Central Amazonia, Brazil

Rhizosphere and bulk soil samples were taken from two perennial plant species (the palm Bactris gasipaes and the dicot Theobroma grandiflorum) growing in an experimental polyculture agroforestry system in Central Amazonia in the wet and the dry season. In the dry season, the soil water potential in the rhizosphere and the bulk soil was below pF 4.2. Microbial biomass and basal respiration were lower in the dry season than in the wet season. However, the lower metabolic quotient in the dry season indicated a higher metabolic efficiency. While the number of oligotrophic microorganisms was not affected by the season, the number of eutrophic microorganisms in the rhizosphere was lower in the dry season than in the wet season. The substrate utilisation pattern of the bacterial community was also affected by the season. Despite marked differences in root morphology there were no significant differences in any of the microbiological parameters between the two plant species. It is concluded that during the dry season, a large portion of the microbial biomass dies off or enters a dormant stage resulting in a change in community composition.

The association between the val/ala-55 polymorphism of the uncoupling protein 2 gene and exercise efficiency.

Energy expenditure may partly be determined by genetic variations in uncoupling proteins. We have previously found an increased physical activity but a similar 24-h energy expenditure (EE) in subjects with the val/val-55 UCP2 genotype compared to those with the ala/ala genotype which indicates that the val-55 allele is statistically associated with a higher metabolic efficiency. EE during bicycling was determined by indirect calorimetry at three different loads (30, 40 and 60% of VO2max in eight subjects with the val/val-55 genotype (35+/-6 y weight=76.8+/-13.6 kg, VO2max=2.79+/-0.71 l/min) and eight subjects with the ala/ala-55 genotype (37+/-3 y, weight=78.3+/-16.5 kg, VO2max=2.66+/-0.41 l/min). Incremental exercise efficiency across the three different work levels was higher in the val/val (25.3%, c.i. 24.2-26.4%) than in the ala/ala (23.6%, c.i. 22.5-24.7%) genotype P<0.05. Gross exercise efficiency at 40% VO2max was higher in the val/val (15.3+/-0.6%) than in the ala/ala (13.5+/-0.4%) group. As the val/ala-55 polymorphism is located in a domain of the protein without any known function, the different exercise efficiency between the two genotypes most likely reflects a linkage disequilibrium with a functionally significant polymorphism in UCP2 or in the neighbouring UCP3 gene. The study suggests that variations in the UCP genes may affect not only basal metabolic rate but also influence energy costs of exercise.

Gravimetric vs. respirometric determination of metabolic efficiency in caterpillars of Pieris brassicae

AbstractConventional gravimetry and a combination of gravimetry and respirometry were compared for their precision in measuring respiration and metabolic efficiency of growth of final stadium Pieris brassicae L. (Pieridae, Lepidoptera) caterpillars. This was done both for caterpillars feeding on an artificial diet and for caterpillars feeding on excised leaf material of a host plant, Brassica oleracea L. Gravimetry produced significantly greater variation in the total amount of matter respired and the metabolic efficiency than indirect calorimetry for caterpillars feeding on plant material, while the two methods gave similar results for the caterpillars reared on a meridic artificial diet. Respirometry (indirect calorimetry) revealed that caterpillars feeding on the artificial diet were growing with a higher metabolic efficiency than caterpillars feeding on the host plant. This difference was not revealed by conventional gravimetry. It is argued that metabolic efficiencies as derived from gravimetric budget calculations are subject to a number of random errors that distort precise determination of metabolic efficiencies in studies involving plant food.

Studies on root nodules of leguminous trees: I. Seasonal variation of plant hormones and IAA metabolism with reference to nitrogen fixation in Pterocarpus mursupiumRoxb

Summary Higher amounts of plant growth substances such as, indole acetic acid (IAA), cytokinin-like substances (CK), gibberellic acid-like substances (GA), abscisic acid-like substance (ABA) were obtained from mature root nodules of the leguminous tree, Pterocarpus mursupium as compared with young or old ones. Higher levels of nitrogenase (N 2 -ase) activity together with IAA metabolism as evaluated by levels of indole acetic acid oxidase (IAA oxidase), methyleneoxindole reductase (MeOx reductase), phenol, peroxidase, and polyphenol oxidase in mature nodules indicated higher metabolic efficiency of mature nodules than in young or old ones. In mature nodules IAA and CK together with N 2 -ase were highest in the rainy season, whereas, GA and ABA were highest in winter. N 2 -ase also was lowest in winter. Thus, N 2 -ase may have positive relations with IAA and CK and negative relations with GA and ABA. Metabolism of IAA, was found to change inversely with the changes of IAA oxidase activity which was again regulated by changes of phenol levels. The phenol level, in turn, was regulated by the activities of peroxidase and polyphenoloxidase in the nodules. Tryptophan (Trp) level showed a positive relation with the IAA level in the nodules. In spite of the variation in content of the hormones with seasons, the size of the nodules was fixed at a definite age in all the seasons indicating that hormone contents were not solely related to the development of nodules. The roots of the plant did not show any N 2 -ase activity and always had lower levels of hormones. The IAA metabolic rate was much more pronounced in roots than in nodules which may be the cause of the lower IAA level in them.