Energy Demand For Maintenance Research Articles

Effects of zinc oxide nanoparticles on carbon mineralization kinetics and microbial attributes in plant residue-amended soils

This study was designed to determine the impacts of different ZnO-NPs concentrations (100–1000 mg kg−1 soil) on soil carbon (C) mineralization of a calcareous soil amended with alfalfa hay (AH) and wheat straw (WS). In addition, C mineralization kinetics in the residue-amended soils were described using different kinetic models and the impacts of ZnO-NPs on the kinetic parameters were investigated. The microbial biomass C (MBC) and basal respiration (BR) were also compared in the treated and control soil samples. The findings revealed a significant reduction in total cumulative mineralized C (Cmin) in soil amended with AH at ZnO-NPs concentrations of 100 and 200 mg−1 kg soil. Similarly, in soil samples amended with WS, the Cmin value demonstrated a significant decrease across all ZnO-NPs concentrations, except for the lowest concentration of 100 mg−1 kg soil. The results of kinetic analysis using the double first-order model showed that the introduction of ZnO-NPs led to an increase of up to 147 % in the amount of C mineralization during the initial fast phase, while it also resulted in a reduction of up to 27.3 % in C mineralization during the subsequent slow phase. Moreover, the presence of ZnO-NPs in the soil resulted in a noteworthy decrease of 4.44 % to 54.5 % in MBC and 5.12 % to 35.7 % in BR values when compared to the uncontaminated soil, suggesting that the size and activity of the soil microbial community were suppressed, with the extent of suppression varying depending on the type of plant residues and concentrations of ZnO-NPs applied. These findings strongly suggest that the soil microbial community was subjected to heightened toxicity stress caused by ZnO-NPs, particularly at higher concentrations. In conclusion, ZnO-NPs can drastically influence the microbial abundance, maintenance energy demand, and C mineralization process in plant residue-amended calcareous soils.

Feed form and perch design do not interact to production performance, gastrointestinal tract traits, behaviour and welfare of laying hens reared in enriched cages

ABSTRACT 1. It was hypothesised that perch material and design may affect utility and maintenance energy demand in laying hens, affecting their feed form preferences and daily feed consumption. Accordingly, perch design and feed form on hen performance, gastrointestinal tract functions and some behavioural and welfare-related traits were studied in laying hens (ATAK-S) reared in enriched colony cages from 24 to 40 weeks of age. 2. The experiment was a 2 × 2 factorial investigating two perch materials and design (circular steel or mushroom-shaped plastic) and feed form (mash or crumble). A total of 396 hens were randomly assigned to one of the four treatment groups with nine replicates each (11 birds per replicate). 3. Except for feeding behaviour and prevalence of foot pad dermatitis at 40 weeks of age, the modification of the perch design did not have a significant effect on the traits examined. Mushroom-shaped plastic perches reduced feeding behaviour (p < 0.01) and the incidence of foot pad dermatitis at 40 weeks of age (p < 0.001). 4. Performance traits were not affected by feed form. Intake, final body weight and FCR for crumble-fed laying hens were greater than those fed mash (p < 0.01). 5. Hens fed mash had higher (p < 0.01) relative gizzard weights along with lower (p < 0.05) pH values, pancreatic chymotrypsin, amylase and lipase activities (p < 0.05), and duodenal absorption surface areas (p < 0.01). Ultimately, this gave higher protein digestibility (p < 0.05) compared to those receiving crumble. 6. In conclusion, in enriched cage rearing systems, mashed feed was preferred over crumble to efficiently maintain productive performance. Compared to circular steel, plastic mushroom-shaped perches were associated with better footpad health and welfare.

Cost and environmental benefit analysis: An assessment of renewable energy integration and smart solution technologies in the InteGRIDy project

The emphasis and focus on energy transition towards a renewable energy-based energy system has increased, alongside the need to understand the economic feasibility of energy system development built around adaptation and implementation of renewable energy resources and smart technologies to a pre-existing energy system. Likewise comes the importance of evaluating and understanding the positive social and environmental impact obtained through energy transition towards a greener and cleaner energy system. This paper applies the cost-benefit analysis method to assess the economic feasibility of implementing renewable energy resources and smart energy technologies in a pre-existing energy system in two pilot sites (St-Jean, France and Barcelona, Spain). The evaluation process encompasses all relevant parameters such as investment, operating and maintenance costs, energy prices, energy demand, energy supply and energy technologies characteristics needed to carry out an economic feasibility assessment of investments and implementation projects. In addition, the evaluation process allows assessing the environmental benefits obtained through implementation by calculating the estimated emission reduction achieved through energy system retrofitting and transition, alongside identifying the society's economic gains attained from the emission reduction. The results show that investing in energy transition and system development toward renewable energy-based energy systems is economically viable since the analysis highlights a considerable low payback period with 8.2 years for the Barcelona pilot, and 2.8 years for St. Jean pilot. Likewise provides significant economic benefits to energy system operators and stakeholders, which is demonstrated with a 22% increase in revenue in the case of the St. Jean pilot and 4% decrease in overall costs at the Barcelona Pilot. The results highlight that energy transition offers various other benefits, such as increasing energy system flexibility with the St Jean pilot experiencing a 21% average increase in energy flexibility in the system through implementation of the energy system development. Also, this includes other benefits such as emission reduction of 23.5% for St. Jean pilot and 4% for the Barcelona pilot, which can help improve public health.

Multi-scale model suggests the trade-off between protein and ATP demand as a driver of metabolic changes during yeast replicative ageing.

The accumulation of protein damage is one of the major drivers of replicative ageing, describing a cell's reduced ability to reproduce over time even under optimal conditions. Reactive oxygen and nitrogen species are precursors of protein damage and therefore tightly linked to ageing. At the same time, they are an inevitable by-product of the cell's metabolism. Cells are able to sense high levels of reactive oxygen and nitrogen species and can subsequently adapt their metabolism through gene regulation to slow down damage accumulation. However, the older or damaged a cell is the less flexibility it has to allocate enzymes across the metabolic network, forcing further adaptions in the metabolism. To investigate changes in the metabolism during replicative ageing, we developed an multi-scale mathematical model using budding yeast as a model organism. The model consists of three interconnected modules: a Boolean model of the signalling network, an enzyme-constrained flux balance model of the central carbon metabolism and a dynamic model of growth and protein damage accumulation with discrete cell divisions. The model can explain known features of replicative ageing, like average lifespan and increase in generation time during successive division, in yeast wildtype cells by a decreasing pool of functional enzymes and an increasing energy demand for maintenance. We further used the model to identify three consecutive metabolic phases, that a cell can undergo during its life, and their influence on the replicative potential, and proposed an intervention span for lifespan control.

On maintenance and metabolisms in soil microbial communities

Biochemistry is an essential yet undervalued aspect of soil ecology, especially when analyzing soil C cycling. We assume, based on tradition, intuition or hope, that the complexity of biochemistry is confined to the microscopic world, and can be ignored when dealing with whole soil systems. This opinion paper draws attention to patterns caused by basic biochemical processes that permeate the world of ecosystem processes. From these patterns, we can estimate activities of the biochemical reactions of the central C metabolic network and gain insights into the ecophysiology of microbial biosynthesis, growth, and maintenance energy requirements: important components of Carbon Use Efficiency (CUE). We show that glucose is processed via the Embden-Meyerhof-Parnas glycolysis in one soil, but via Pentose Phosphate or Entner-Doudoroff pathways in two other soils. However, notwithstanding this metabolic diversity, glucose use efficiency is high and thus substrate use for maintenance energy and overflow respiration is low in these soils. These results contradict current dogma, based on four decades of debate in soil ecology, that the maintenance energy demand in soil communities is a quantitative important, although variable, component of soil community energy metabolism. We identify three main shortcomings in our current understanding of substrate use efficiency: 1) in numeric and conceptual models, we lack appreciation of the strategies that microbes employ to quickly reduce energy needs in response to starvation; 2) in order to understand variation in CUE, we need to improve our understanding of the processes of exudation (including all changes in allocation of C from the cell soluble to insoluble fraction and extracellular environment) and microbial turnover; and 3) whether tracer experiments can be used to measure the long-term substrate use efficiency of soil microbial communities depends critically on the ability and speed with which non-growing cells take up tracer substrates and metabolism activates and subsequently de-activates in response to starvation, as well as on how cellular activities scale to the community level. To move the field of soil ecology forward, future research must consider the details of microbial ecophysiology and develop new tools that enable direct measurement of microbial functioning in intact soils. We submit that 13C metabolic flux analysis is one of those new tools.

Optimization of Profit for Pasture-Based Beef Cattle and Sheep Farming Using Linear Programming: Young Beef Cattle Production in New Zealand

In New Zealand, surplus dairy-origin calves not needed as replacement or for beef cattle farms requirements for finishing are commercially slaughtered within two weeks of age. This system has perceived ethical issues which can potentially negatively affect the dairy industry. Therefore, a young beef cattle production system to maximize the use of excess calves within the land size constraint is considered as an alternative to a traditional 18 to 33-months slaughtering system. The current study examined the effects of young beef cattle production with slaughter ages at 8 to 14 months on pasture utilization, farm profitability and selling policy on class 5, intensive finishing sheep and beef cattle farms in New Zealand. A linear programming model that had previously been developed for this farm class (optimized traditional beef cattle system) was modified to include a young beef cattle slaughter system and identified the carrying capacity for young and traditional beef cattle and the selling policy required to optimize pasture utilization and farm profitability. Systems with young beef cattle slaughtered at 8, 10, 12 or 14-months of age were simulated without (Scenario I) or with (Scenario II) decreasing the number of traditional beef cattle. Daily per head energy demand for maintenance and live weight change was estimated and converted to kg DM/head on a bimonthly basis. Carcasses from young beef cattle were processed as one class under manufacturing beef price (NZ$4.50). The modified young and traditional beef cattle slaughtering system maintained an extra 6% and 35% beef cattle in Scenario I and Scenario II respectively, and finished 90% and 84% of traditional beef cattle before the second winter. Pasture supplied 98% of the feed demand for the beef cattle activities and 79–83% of that was consumed. Mixed young and traditional beef cattle finishing scenarios returned 2% less gross farm revenue per hectare (GFR/ha). However, earnings before tax per hectare (ETB/ha) in Scenario I and Scenario II were 15–25% greater than that of the optimized traditional beef cattle system, respectively. Young beef cattle production increased pasture utilization and farm profitability and increased selling options for finished beef cattle. Therefore, the young beef cattle system is a viable option for farmers and will help to reduce the need to slaughter calves within two weeks of age.

Maintenance power requirements of anammox bacteria "Candidatus Brocadia sinica" and "Candidatus Scalindua sp."

Little is known about the cell physiology of anammox bacteria growing at extremely low growth rates. Here, "Candidatus Brocadia sinica" and "Candidatus Scalindua sp." were grown in continuous anaerobic membrane bioreactors (MBRs) with complete biomass retention to determine maintenance energy (i.e., power) requirements at near-zero growth rates. After prolonged retentostat cultivations, the specific growth rates (μ) of "Ca. B. sinica" and "Ca. Scalindua sp." decreased to 0.000023 h-1 (doubling time of 1255 days) and 0.000157 h-1 (184 days), respectively. Under these near-zero growth conditions, substrate was continuously utilized to meet maintenance energy demands (me) of 6.7 ± 0.7 and 4.3 ± 0.7 kJ mole of biomass-C-1 h-1 for "Ca. B. sinica" and "Ca. Scalindua sp.", which accorded with the theoretically predicted values of all anaerobic microorganisms (9.7 and 4.4 kJ mole of biomass-C-1 h-1at 37 °C and 28 °C, respectively). These me values correspond to 13.4 × 10-15 and 8.6 × 10-15 watts cell-1 for "Ca. B. sinica" and "Ca. Scalindua sp.", which were five orders of magnitude higher than the basal power limit for natural settings (1.9 × 10-19 watts cells-1). Furthermore, the minimum substrate concentrations required for growth (Smin) were calculated to be 3.69 ± 0.21 and 0.09 ± 0.05 μM NO2- for "Ca. B. sinica" and "Ca. Scalindua sp.", respectively. These results match the evidence that "Ca. Scalindua sp." with lower maintenance power requirement and Smin are better adapted to energy-limited natural environments than "Ca. B. sinica", suggesting the importance of these parameters on ecological niche differentiation in natural environments.

Transcriptomic analysis of the ark shell Scapharca kagoshimensis: De novo assembly and identification of genes and pathways involved growth

To understand the molecular mechanism associated with growth variability in bivalves, we employed Illumina RNA-seq technology to analyze the transcriptomic profiles from fast- and slow-growing individuals in one full-sib family of the ark shell, Scapharca kagoshimensis. De novo assembly of S. kagoshimensis transcriptome yielded 276,082,016 raw reads, which were assembled into 98,502 unique transcripts using the Trinity strategy. A total of 6357 differentially expressed genes (DEGs) were obtained between fast- and slow-growing individuals, with 68 up-regulated genes and 846 down-regulated genes. Functional annotation revealed that most of the DEGs were classified to subunits of the large or small ribosomal protein, all of which showed significantly lower expression levels in the fast-growing group than those in the slow-growing group. Gene Ontology (GO) enrichment analysis indicated that most of the DEGs were involved in biological processes, followed by molecular functions and cellular components. The most Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enriched genes were related to energy metabolism, protein synthesis and degradation. These findings presented the potential links between genes expression and contrasting phenotypes in the ark shell, suggesting that the fast-growing phenotype might be attributed to lower energy demands for metabolism maintenance, and more effective protein biosynthesis and degradation in bivalves.

Energetics of Acidianus ambivalens growth in response to oxygen availability.

All life requires energy to drive metabolic reactions such as growth and cell maintenance; therefore, fluctuations in energy availability can alter microbial activity. There is a gap in our knowledge concerning how energy availability affects the growth of extreme chemolithoautotrophs. Toward this end, we investigated the growth of thermoacidophile Acidianus ambivalens during sulfur oxidation under aerobic to microaerophilic conditions. Calorimetry was used to measure enthalpy (ΔHinc ) of microbial activity, and chemical changes in growth media were measured to calculate Gibbs energy change (ΔGinc ) during incubation. In all experiments, Gibbs energy was primarily dissipated through the release of heat, which suggests enthalpy-driven growth. In microaerophilic conditions, growth was significantly more efficient in terms of biomass yield (defined as C-mol biomass per mole sulfur consumed) and resulted in lower ΔGinc and ΔHinc . ΔGinc in oxygen-limited (OL) and oxygen- and CO2 -limited (OCL) microaerophilic growth conditions resulted in averages of -1.44×103 kJ/C-mol and -7.56×102 kJ/C-mol, respectively, and average ΔHinc values of -1.11×105 kJ/C-mol and -4.43×104 kJ/C-mol, respectively. High-oxygen experiments resulted in lower biomass yield values, an increase in ΔGinc to -1.71×104 kJ/C-mol, and more exothermic ΔHinc values of -4.71×105 kJ/C-mol. The observed inefficiency in high-oxygen conditions may suggest larger maintenance energy demands due to oxidative stresses and a preference for growth in microaerophilic environments.

Determining incremental coulombic efficiency and physiological parameters of early stage Geobacter spp. enrichment biofilms.

Geobacter spp. enrichment biofilms were cultivated in batch using one-chamber and two-chamber bioelectrochemical reactors. Time-resolved substrate quantification was performed to derive physiological parameters as well as incremental coulombic efficiency (i.e., coulombic efficiency during one batch cycle, here every 6h) during early stage biofilm development. The results of one-chamber reactors revealed an intermediate acetate increase putatively due to the presence of acetogens. Total coulombic efficiencies of two-chamber reactors were considerable lower (19.6±8.3% and 49.3±13.2% for 1st and 2nd batch cycle, respectively) compared to usually reported values of mature Geobacter spp. enrichment biofilms presumably reflecting energetic requirements for biomass production (i.e., cells and extracellular polymeric substances) during early stages of biofilm development. The incremental coulombic efficiency exhibits considerable changes during batch cycles indicating shifts between phases of maximizing metabolic rates and maximizing biomass yield. Analysis based on Michaelis-Menten kinetics yielded maximum substrate uptake rates (vmax,Ac, vmax,I) and half-saturation concentration coefficients (KM,Ac,KM,I) based on acetate uptake or current production, respectively. The latter is usually reported in literature but neglects energy demands for biofilm growth and maintenance as well as acetate and electron storage. From 1st to 2nd batch cycle, vmax,Ac and KM,Ac, decreased from 0.0042–0.0051 mmol Ac− h−1 cm−2 to 0.0031–0.0037 mmol Ac− h−1 cm−2 and 1.02–2.61 mM Ac− to 0.28–0.42 mM Ac−, respectively. Furthermore, differences between KM,Ac/KM,I and vmax,Ac/vmax,I were observed providing insights into the physiology of Geobacter spp. enrichment biofilms. Notably, KM,I considerably scattered while vmax,Ac/vmax,I and KM,Ac remained rather stable indicating that acetate transport within biofilm only marginally affects reaction rates. The observed data variation mandates the requirement of a more detailed analysis with an improved experimental system, e.g., using flow conditions and a comparison with Geobacter spp. pure cultures.

Position-Specific Metabolic Probing and Metagenomics of Microbial Communities Reveal Conserved Central Carbon Metabolic Network Activities at High Temperatures.

Temperature is a primary driver of microbial community composition and taxonomic diversity; however, it is unclear to what extent temperature affects characteristics of central carbon metabolic pathways (CCMPs) at the community level. In this study, 16S rRNA gene amplicon and metagenome sequencing were combined with 13C-labeled metabolite probing of the CCMPs to assess community carbon metabolism along a temperature gradient (60–95°C) in Great Boiling Spring, NV. 16S rRNA gene amplicon diversity was inversely proportional to temperature, and Archaea were dominant at higher temperatures. KO richness and diversity were also inversely proportional to temperature, yet CCMP genes were similarly represented across the temperature gradient and many individual metagenome-assembled genomes had complete pathways. In contrast, genes encoding cellulosomes and many genes involved in plant matter degradation and photosynthesis were absent at higher temperatures. In situ 13C-CO2 production from labeled isotopomer pairs of glucose, pyruvate, and acetate suggested lower relative oxidative pentose phosphate pathway activity and/or fermentation at 60°C, and a stable or decreased maintenance energy demand at higher temperatures. Catabolism of 13C-labeled citrate, succinate, L-alanine, L-serine, and L-cysteine was observed at 85°C, demonstrating broad heterotrophic activity and confirming functioning of the TCA cycle. Together, these results suggest that temperature-driven losses in biodiversity and gene content in geothermal systems may not alter CCMP function or maintenance energy demands at a community level.

Augmenting Biogas Process Modeling by Resolving Intracellular Metabolic Activity.

The process of anaerobic digestion in which waste biomass is transformed to methane by complex microbial communities has been modeled for more than 16 years by parametric gray box approaches that simplify process biology and do not resolve intracellular microbial activity. Information on such activity, however, has become available in unprecedented detail by recent experimental advances in metatranscriptomics and metaproteomics. The inclusion of such data could lead to more powerful process models of anaerobic digestion that more faithfully represent the activity of microbial communities. We augmented the Anaerobic Digestion Model No. 1 (ADM1) as the standard kinetic model of anaerobic digestion by coupling it to Flux-Balance-Analysis (FBA) models of methanogenic species. Steady-state results of coupled models are comparable to standard ADM1 simulations if the energy demand for non-growth associated maintenance (NGAM) is chosen adequately. When changing a constant feed of maize silage from continuous to pulsed feeding, the final average methane production remains very similar for both standard and coupled models, while both the initial response of the methanogenic population at the onset of pulsed feeding as well as its dynamics between pulses deviates considerably. In contrast to ADM1, the coupled models deliver predictions of up to 1,000s of intracellular metabolic fluxes per species, describing intracellular metabolic pathway activity in much higher detail. Furthermore, yield coefficients which need to be specified in ADM1 are no longer required as they are implicitly encoded in the topology of the species’ metabolic network. We show the feasibility of augmenting ADM1, an ordinary differential equation-based model for simulating biogas production, by FBA models implementing individual steps of anaerobic digestion. While cellular maintenance is introduced as a new parameter, the total number of parameters is reduced as yield coefficients no longer need to be specified. The coupled models provide detailed predictions on intracellular activity of microbial species which are compatible with experimental data on enzyme synthesis activity or abundance as obtained by metatranscriptomics or metaproteomics. By providing predictions of intracellular fluxes of individual community members, the presented approach advances the simulation of microbial community driven processes and provides a direct link to validation by state-of-the-art experimental techniques.

A physical model of cell metabolism

Cell metabolism is characterized by three fundamental energy demands: to sustain cell maintenance, to trigger aerobic fermentation and to achieve maximum metabolic rate. The transition to aerobic fermentation and the maximum metabolic rate are currently understood based on enzymatic cost constraints. Yet, we are lacking a theory explaining the maintenance energy demand. Here we report a physical model of cell metabolism that explains the origin of these three energy scales. Our key hypothesis is that the maintenance energy demand is rooted on the energy expended by molecular motors to fluidize the cytoplasm and counteract molecular crowding. Using this model and independent parameter estimates we make predictions for the three energy scales that are in quantitative agreement with experimental values. The model also recapitulates the dependencies of cell growth with extracellular osmolarity and temperature. This theory brings together biophysics and cell biology in a tractable model that can be applied to understand key principles of cell metabolism.

Dynamic of Metabolic Indicators, Insulin Like-growth Factor I (IGF-I) and Cortisol in Holstein Cows during the Transition Period

Background: Physiological events occur in the transition period marked by negative energetic balance, where the energetic demand is higher due to fetal nutrition and lactogenesis and intensified by the decrease of the dry matter intake in the pre-partum period. The adaptation of cows is dependent of homeostatic and homeorhetic mechanisms regulated by catecholamine, cortisol, GH, IGF-I, insulin and glucagon but the priorization of homeorhetic mechanisms could result in metabolic diseases. Considering the scarce longitudinal studies about the Brazilian conditions the aim of this project was to evaluate the influence of transition period on metabolic indicators, cortisol and IGF-I in Holstein cows.Materials, Methods &amp; Results: Thirteen cows, from 2nd to 4th lactation were evaluated weakly from week -2 to week +3 in relation to calving to determine the body condition score (BCS), metabolic and endocrine profile. The BCS decreased between week -2 (BCS = 4.0) and +1 (BCS = 3.0), followed by and slight increase on weeks +2 and +3 (P = 0.000). The most of metabolic indicators and hormones have changed during the transition period (P ≤ 0.05), especially around calving. It was possible to detect the peak of cortisol, glucose, non-esterified fatty acids (NEFA), ß-hydroxibutyrate (BHB), and aspartate aminotransferase (AST) on delivery and week +1. On the other hand, total calcium, triglycerides (TG) and cholesterol (CHOL) decreased was observed around parturition. Insulin like growth factor type I (IGF-I) showed marked reduction between pre and postpartum, and the lowest value was observed in the week +1. TP and GLOB had the lowest value on calving and globulin has a gradual increase from delivery to week +3.Discussion: Cows included in this experiment had dystocia (4/13, 30.8%), retention of placenta (1/13, 7.7%) and clinical hypocalcemia (1/13, 7.7%). One of the animals with episodes of dystocia was also aggravated by ketosis in week +1 and +2 (1/13, 7.7%). Uterine infections were observed in five animals (5/13, 38.4%). Of this total of animals with uterine infection (5/13), three had already expressed earlier disturbances: two cows had dystocia and one cow with retention of placenta. The weight loss observed between pre and postpartum may be due to an increase of energy demand for fetal maintenance and the concomitant initiation of lactation, in conjunction with an approximately 30% reduction in dry matter intake during the transitional period. The hyperglycemia concomitant with the peak of cortisol at delivery may be explaining by the activation of the somatotropic axis, due to the stress of calving. The increase of NEFA, BHB and AST around calving associated with decreased of TG and CHOL could be associated with homeorhetic mechanisms, especially lipolysis and gluconeogenesis. The IGF-I decrease in postpartum may be by the decreased expression of receptors for growth hormone (GH) in the liver, and consequently reduced synthesis and/or IGF-I hepatic clearance, which reduce of the negative feedback of IGF-I on GH secretion. The total calcium concentrations were below the threshold (8.50 mg/dL) established by Goff [10] at parturition, week +1 and +2 and probably is due to the secretion of 20-30 g of calcium per day during the colostrum synthesis. Total protein and albumin have a slight variation, except for the peak observed on week +3 due to uterine infection.Keywords: body condition score, non-esterified fatty acids, ß-hydroxibutyrate, total calcium, hormones.

Dynamic of Metabolic Indicators, Insulin Like-growth Factor I (IGF-I) and Cortisol in Holstein Cows during the Transition Period

Background: Physiological events occur in the transition period marked by negative energetic balance, where the energetic demand is higher due to fetal nutrition and lactogenesis and intensified by the decrease of the dry matter intake in the pre-partum period. The adaptation of cows is dependent of homeostatic and homeorhetic mechanisms regulated by catecholamine, cortisol, GH, IGF-I, insulin and glucagon but the priorization of homeorhetic mechanisms could result in metabolic diseases. Considering the scarce longitudinal studies about the Brazilian conditions the aim of this project was to evaluate the influence of transition period on metabolic indicators, cortisol and IGF-I in Holstein cows.Materials, Methods &amp; Results: Thirteen cows, from 2nd to 4th lactation were evaluated weakly from week -2 to week +3 in relation to calving to determine the body condition score (BCS), metabolic and endocrine profile. The BCS decreased between week -2 (BCS = 4.0) and +1 (BCS = 3.0), followed by and slight increase on weeks +2 and +3 (P = 0.000). The most of metabolic indicators and hormones have changed during the transition period (P ≤ 0.05), especially around calving. It was possible to detect the peak of cortisol, glucose, non-esterified fatty acids (NEFA), ß-hydroxibutyrate (BHB), and aspartate aminotransferase (AST) on delivery and week +1. On the other hand, total calcium, triglycerides (TG) and cholesterol (CHOL) decreased was observed around parturition. Insulin like growth factor type I (IGF-I) showed marked reduction between pre and postpartum, and the lowest value was observed in the week +1. TP and GLOB had the lowest value on calving and globulin has a gradual increase from delivery to week +3.Discussion: Cows included in this experiment had dystocia (4/13, 30.8%), retention of placenta (1/13, 7.7%) and clinical hypocalcemia (1/13, 7.7%). One of the animals with episodes of dystocia was also aggravated by ketosis in week +1 and +2 (1/13, 7.7%). Uterine infections were observed in five animals (5/13, 38.4%). Of this total of animals with uterine infection (5/13), three had already expressed earlier disturbances: two cows had dystocia and one cow with retention of placenta. The weight loss observed between pre and postpartum may be due to an increase of energy demand for fetal maintenance and the concomitant initiation of lactation, in conjunction with an approximately 30% reduction in dry matter intake during the transitional period. The hyperglycemia concomitant with the peak of cortisol at delivery may be explaining by the activation of the somatotropic axis, due to the stress of calving. The increase of NEFA, BHB and AST around calving associated with decreased of TG and CHOL could be associated with homeorhetic mechanisms, especially lipolysis and gluconeogenesis. The IGF-I decrease in postpartum may be by the decreased expression of receptors for growth hormone (GH) in the liver, and consequently reduced synthesis and/or IGF-I hepatic clearance, which reduce of the negative feedback of IGF-I on GH secretion. The total calcium concentrations were below the threshold (8.50 mg/dL) established by Goff [10] at parturition, week +1 and +2 and probably is due to the secretion of 20-30 g of calcium per day during the colostrum synthesis. Total protein and albumin have a slight variation, except for the peak observed on week +3 due to uterine infection.

Integrated regulatory network reveals novel candidate regulators in the development of negative energy balance in cattle

Negative energy balance (NEB) is an altered metabolic state in modern high-yielding dairy cows. This metabolic state occurs in the early postpartum period when energy demands for milk production and maintenance exceed that of energy intake. Negative energy balance or poor adaptation to this metabolic state has important effects on the liver and can lead to metabolic disorders and reduced fertility. The roles of regulatory factors, including transcription factors (TFs) and micro RNAs (miRNAs) have often been separately studied for evaluating of NEB. However, adaptive response to NEB is controlled by complex gene networks and still not fully understood. In this study, we aimed to discover the integrated gene regulatory networks involved in NEB development in liver tissue. We downloaded data sets including mRNA and miRNA expression profiles related to three and four cows with severe and moderate NEB, respectively. Our method integrated two independent types of information: module inference network by TFs, miRNAs and mRNA expression profiles (RNA-seq data) and computational target predictions. In total, 176 modules were predicted by using gene expression data and 64 miRNAs and 63 TFs were assigned to these modules. By using our integrated computational approach, we identified 13 TF-module and 19 miRNA-module interactions. Most of these modules were associated with liver metabolic processes as well as immune and stress responses, which might play crucial roles in NEB development. Literature survey results also showed that several regulators and gene targets have already been characterized as important factors in liver metabolic processes. These results provided novel insights into regulatory mechanisms at the TF and miRNA levels during NEB. In addition, the method described in this study seems to be applicable to construct integrated regulatory networks for different diseases or disorders.

Impact of Ocean Acidification and Warming on the bioenergetics of developing eggs of Atlantic herring Clupea harengus.

Atlantic herring (Clupea harengus) is a benthic spawner, therefore its eggs are prone to encounter different water conditions during embryonic development, with bottom waters often depleted of oxygen and enriched in CO2. Some Atlantic herring spawning grounds are predicted to be highly affected by ongoing Ocean Acidification and Warming with water temperature increasing by up to +3°C and CO2 levels reaching ca. 1000 μatm (RCP 8.5). Although many studies investigated the effects of high levels of CO2 on the embryonic development of Atlantic herring, little is known about the combination of temperature and ecologically relevant levels of CO2. In this study, we investigated the effects of Ocean Acidification and Warming on embryonic metabolic and developmental performance such as mitochondrial function, respiration, hatching success (HS) and growth in Atlantic herring from the Oslo Fjord, one of the spawning grounds predicted to be greatly affected by climate change. Fertilized eggs were incubated under combinations of two PCO2 conditions (400 μatm and 1100 μatm) and three temperatures (6, 10 and 14°C), which correspond to current and end-of-the-century conditions. We analysed HS, oxygen consumption (MO2) and mitochondrial function of embryos as well as larval length at hatch. The capacity of the electron transport system (ETS) increased with temperature, reaching a plateau at 14°C, where the contribution of Complex I to the ETS declined in favour of Complex II. This relative shift was coupled with a dramatic increase in MO2 at 14°C. HS was high under ambient spawning conditions (6-10°C), but decreased at 14°C and hatched larvae at this temperature were smaller. Elevated PCO2 increased larval malformations, indicating sub-lethal effects. These results indicate that energetic limitations due to thermally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.

Point stresses during reproductive stage rather than warming seasonal temperature determine yield in temperate rice.

Climate change is predicted to shift temperature regimes in most agricultural areas with temperature changes expected to impact yields of most crops, including rice. These temperature-driven effects can be classified into point stresses, where a temperature event during a sensitive stage drives a reduction in yield, or seasonal warming losses, where raised temperature is thought to increase maintenance energy demands and thereby decrease available resources for yield formation. Simultaneous estimation of the magnitude of each temperature effect on yield has not been well documented due to the inherent difficulty in separating their effects. We simultaneously quantified the magnitude of each effect for a temperate rice production system using a large data set covering multiple locations with data collected from 1995 to 2015, combined with a unique probability-based modeling approach. Point stresses, primarily cold stress during the reproductive stages (booting and flowering), were found to have the largest impact on yield (over 3Mg/ha estimated yield losses). Contrary to previous reports, yield losses caused by increased temperatures, both seasonal and during grain-filling, were found to be small (approximately 1-2% loss per °C). Occurrences of cool temperature events during reproductive stages were found to be persistent over the study period, and within season, the likelihood of a cool temperature event increased when flowering occurred later in the season. Short and medium grain types, typically recommended for cool regions, were found to be more tolerant of cool temperatures but more sensitive to heat compared to long grain cultivars. These results suggest that for temperate rice systems, the occurrence of periodic stress events may currently overshadow the impacts of general warming temperature on crop production.

Pichia pastoris Exhibits High Viability and a Low Maintenance Energy Requirement at Near-Zero Specific Growth Rates.

ABSTRACTThe yeast Pichia pastoris is a widely used host for recombinant protein production. Understanding its physiology at extremely low growth rates is a first step in the direction of decoupling product formation from cellular growth and therefore of biotechnological relevance. Retentostat cultivation is an excellent tool for studying microbes at extremely low specific growth rates but has so far not been implemented for P. pastoris. Retentostat feeding regimes were based on the maintenance energy requirement (mS) and maximum biomass yield on glucose (YX/Smax) estimated from steady-state glucose-limited chemostat cultures. Aerobic retentostat cultivation enabled reproducible, smooth transitions from a specific growth rate (μ) of 0.025 h−1 to near-zero specific growth rates (μ < 0.001 h−1). At these near-zero specific growth rates, viability remained at least 97%. The value of mS at near-zero growth rates was 3.1 ± 0.1 mg glucose per g biomass and h, which was 3-fold lower than the mS estimated from faster-growing chemostat cultures. This difference indicated that P. pastoris reduces its maintenance energy requirement at extremely low μ, a phenomenon not previously observed in eukaryotes. Intracellular levels of glycogen and trehalose increased, while μ progressively declined during retentostat cultivation. Transcriptional reprogramming toward zero growth included the upregulation of many transcription factors as well as stress-related genes and the downregulation of cell cycle genes. This study underlines the relevance of comparative analysis of maintenance energy metabolism, which has an important impact on large-scale industrial processes.IMPORTANCE The yeast Pichia pastoris naturally lives on trees and can utilize different carbon sources, among them glucose, glycerol, and methanol. In biotechnology, it is widely used for the production of recombinant proteins. For both the understanding of life in its natural habitat and optimized production processes, a better understanding of cell physiology at an extremely low growth rate would be of extraordinary value. Therefore, we have grown P. pastoris in a retentostat, which allows the cultivation of metabolically active cells even at zero growth. Here we reached doubling times as long as 38 days and found that P. pastoris decreases its maintenance energy demand 3-fold during very slow growth, which enables it to survive with a much lower substrate supply than baker's yeast.

Development of a nutritional model to define the energy and protein requirements of cobia, Rachycentron canadum

This study assessed the protein and energy requirements of Cobia (Rachycentron canadum) using a bio-energetic factorial approach. Using a series of inter-related studies, several parameters were defined to enable the construction of a bio-energetic factorial model for this species. The studies included two controlled laboratory experiments and also extensive field-data collection from commercial and research farms in Vietnam. The devised model includes parameters for both maintenance and protein demands; the effect of fish live-weight on maintenance protein (LW0.697), lipid (LW0.972), and energy demands (LW0.815); the efficiencies of protein, lipid and energy utilisation at various protein, lipid and energy intake levels; and the variability in whole body composition with varying live-weight. The protein utilisation efficiencies (0.456·[protein intake]−0.445), lipid utilisation efficiencies (1.292·[lipid intake]−1.120) and energy utilisation efficiencies (0.651·[energy intake]−48.41) were similar to other carnivorous fish species. However, the maintenance requirements for both energy (74.3kJ/kgBW0.8/d− at 28°C) and protein (0.99g/kgBW0.7/d at 27.9°C) were about double to other species. Using this modelling approach it was possible to iteratively derive optimal dietary protein and energy specifications for this species.