Effects of energy content and energy density of pre-portioned entrées on energy intake

Pre-portioned entrées are commonly consumed to help control portion size and limit energy intake. The influence of entrée characteristics on energy intake, however, has not been well studied. We determined how the effects of energy content and energy density (ED, kcal/g) of pre-portioned entrées combine to influence daily energy intake. In a crossover design, 68 non-dieting adults (28 men and 40 women) were provided with breakfast, lunch, and dinner on 1 day a week for 4 weeks. Each meal included a compulsory, manipulated pre-portioned entrée followed by a variety of unmanipulated discretionary foods that were consumed ad libitum. Across conditions, the entrées were varied in both energy content and ED between a standard level (100%) and a reduced level (64%). Results showed that in men, decreases in the energy content and ED of pre-portioned entrées acted independently and added together to reduce daily energy intake (both P < 0.01). Simultaneously decreasing the energy content and ED reduced total energy intake in men by 16% (445 ± 47 kcal/day; P < 0.0001). In women, the entrée factors also had independent effects on energy intake at breakfast and lunch, but at dinner and for the entire day the effects depended on the interaction of the two factors (P < 0.01). Simultaneously decreasing the energy content and ED reduced daily energy intake in women by 14% (289 ± 35 kcal/day; P < 0.0001). Both the energy content and ED of pre-portioned entrées affect daily energy intake and could influence the effectiveness of such foods for weight management.     

Fluorescence lifetime,yield, energy transfer and spectrum in photosynthesis, 1950–1960*

The fluorescence lifetime of chlorophyll agives information about the primary photo-physical events in photosynthesis. Most of the light energy absorbed by chlorophylls is utilized for photochemistry. There are two main additional pathways competing for the absorbed light energy: fluorescence and radiationless internal conversion (heat). Only a few percent of the absorbed energy proceeds along these two pathways. This historical minireview focuses on the first direct measurements of the lifetime of chlorophyll fluorescence, the time it takes to transfer energy from phycoerythrin to chlorophyll a, and the discovery of the fluorescence band at 720 nm (F720; then attributed to a dimer of chlorophyll). These works were carried out during the the late 1950s to the early 1960s in the laboratory of Professor Eugene Rabinowitch at the University of Illinois, Urbana-Champaign [Brody (1995) Photosynth Res 43: 67–74]. This Minireview is dedicated to Professor Eugene Rabinowitch (1901–1973), mentor of the author (Steve Brody) as well as of the editor, and authors classmate (Govindjee). The career and contributions of Eugene Rabinowitch are available in a dedication by Bannister (1972). This revised version was published online in June 2006 with corrections to the Cover Date.     

Weather,microclimate, and energy costs of thermoregulation for breeding Adélie Penguins

Summary We measured meteorological conditions and estimated the energy costs of thermoregulation for young and adult Adélie Penguins (Pygoscelis adeliae) at a breeding colony near the Antarctic Peninsula. Air temperatures averaged < 5°C and strong winds were frequent. Operative temperatures (T_e) for adults ranged from –8 to 28°C, averaging 5–6°C, for the period from courtship to fledging of chicks. The average energy cost of thermoregulation (C_th) for adult penguins was equivalent to 10–16% of basal metabolism. C_th comprised about 15% of the estimated daily energy budget (DEB) of incubating adults, but only about 1% of the DEB of adults feeding chicks. The T_e's for chicks older than 14 days ranged from 0 to 31°C, averaging 8.0 C. The C_th for downy chicks ranged from about 31% of minimal metabolic rate (MMR) in 1 kg chicks to about 10% of MMR in 3 kg chicks. Between initial thermal independence (age 12–14 days) and the cessation of parental feeding (age 35–40 days), chicks use about 10–11% of assimilated energy for thermoregulation. C_th is equivalent to about 17% of the MMR of fledglings during their 2–3 week fast. We observed no indication of thermal stress (i.e., conditions in which birds cannot maintain stable T_b) in adults and no indication of cold stress in any age class. However, on clear, calm days when air temperature exceeds 7–10°C for several hours, downy chicks are vulnerable to lethal hyperthermia.     

Disentangling the relative effects of ambient energy,water availability,and energy–water balance on pteridophyte species richness at a landscape scale in China

Understanding what factors generate geographic variation in species richness is a fundamental goal of ecology and biogeography. Water and energy are considered as the major environmental factors influencing large-scale patterns of species richness, but their roles vary among taxa and regions. Pteridophytes are an ideal group of organisms for examining the relationship between species richness and their environment because the distribution of pteridophytes is usually in equilibrium with contemporary climate to a greater degree than those of seed plants and most terrestrial vertebrates partly due to the lightness of their spores, which is highly capable of long-distance dispersal by wind, and partly due to their single-spore reproduction strategy. Using correlation and regression analyses and structural equation modeling technique, we examine the relationship of pteridophyte species richness in 151 localities from across China with environmental factors representing energy, water, and energy–water balance. We found that pteridophyte species richness is correlated to water availability more strongly than to ambient energy. Furthermore, we found that of all environmental variables considered, energy–water balance has played the most important role in regulating pteridophyte species richness gradients in China.     

Reductions in entrée energy density increase children's vegetable intake and reduce energy intake

The energy density (ED; kcal/g) of an entrée influences children's energy intake (EI), but the effect of simultaneously changing both ED and portion size of an entrée on preschool children's EI is unknown. In this within-subject crossover study, 3- to 5-year-old children (30 boys, 31 girls) in a daycare facility were served a test lunch once/week for 4 weeks. The amount and type of vegetables and cheeses incorporated into the sauce of a pasta entrée were manipulated to create two versions that varied in ED by 25% (1.6 or 1.2 kcal/g). Across the weeks, each version of the entrée was served to the children in each of two portion sizes (400 or 300 g). Lunch, consumed ad libitum, also included carrots, applesauce, and milk. Decreasing ED of the entrée by 25% significantly (P<0.0001) reduced children's EI of the entrée by 25% (63.1+/-8.3 kcal) and EI at lunch by 17% (60.7+/-8.9 kcal). Increasing the proportion of vegetables in the pasta entrée increased children's vegetable intake at lunch by half of a serving of vegetables (P<0.01). Decreasing portion size of the entrée by 25% did not significantly affect children's total food intake or EI at lunch. Therefore, reducing the ED of a lunch entrée resulted in a reduction in children's EI from the entrée and from the meal in both portion size conditions. Decreasing ED by incorporating more vegetables into recipes is an effective way of reducing children's EI while increasing their vegetable intake.     

Control of magnesium–protoporphyrin chelatase activity in Rhodopseudomonas spheroides. Role of light, oxygen, and electron and energy transfer

1. Magnesium-protoporphyrin chelatase activity, previously shown in whole cells of Rhodopseudomonas spheroides, could not be demonstrated in cell-free extracts prepared in different ways, although spheroplasts retained moderate activity. Slight activity was detected also in whole cells of Rhodospirillum rubrum. 2. The effects on the activity of the enzyme of inhibitors of electron and energy transfer were studied in whole cells of Rps. spheroides. Amytal, rotenone, azide and cyanide inhibited at low pO(2) in the dark but not under anaerobic conditions in the light. Antimycin A and 2-heptyl-4-hydroxyquinoline N-oxide, as well as uncouplers and oligomycin, inhibited under all environmental conditions. 3. The effects on magnesium chelatase activity of intermediates of the tricarboxylic acid cycle, of thenoyltrifluoroacetone, of a number of artificial electron donors or acceptors, of various quinones and of the oxidation-reduction indicator dyes Benzyl Viologen and Methyl Viologen are described. 4. It was concluded that electron transport between a b-type and a c-type cytochrome as well as associated energy conservation and transformation reactions were essential for activity. There was also a specific requirement for ATP. 5. Exogenous protoporphyrin and magnesium protoporphyrin monomethyl ester were incorporated into bacteriochlorophyll or late precursors by whole cells. 6. Evidence is presented that the insertion of magnesium was the only step inhibited by oxygen in the biosynthetic pathway between protoporphyrin and bacteriochlorophyll.     

Contents,accumulation and release of energy in green,dead and decomposing plant materials in an upland grassland near Kameničky,Czechoslovakia

The energy content was studied in above-ground live plant material and in litter in a natural grassland ecosystem with dominantNardus stricto l., defined phytosociologically asPolygalo-Nardetum strictae Preising 1950 corr. Oberdorfer 1957, and in two of its fertilized variants in the course of 1975 to 1977. Based on the determined production characteristics and data on decomposition processes, the amounts of energy accumulated by the green parts of the stands and the amount of energy released during decomposition from the litter were calculated. Changes in the energy content of litter in different stages of decomposition were determined. With progressing decomposition the energy content per gram ash-free decomposing plant litter increases.     

Long-term trends,seasonal abundance and energy consumption of waterbirds at Rietvlei,Western Cape,South Africa, 1950–1997

Waterbird counts at Rietvlei, a freshwater wetland in the Western Cape, were analysed for four periods: 1950–56, 1961–67, 1980–85 and 1992–97. Ninety-eight species of waterbirds were recorded during these counts. Palaearctic migrants predominated during summer, with Curlew Sandpipers, Calidris ferruginea, being the mast abundant species in all years, except in the 1960s and 1950s when Red-knobbed Coots, Fulica cristata, and Ruffs, Philomachus pugnax, outnumbered them respectively. Red-knobbed Coots and Yellow-billed Ducks, Anas undulata, were the most numerous species during winter in all years. The numbers of waterbirds at Rietvlei have shown a progressive increase since the 1950s, reaching over 8300 birds in the mid-summer of 1997. The increase in abundance of several species is attributed to changes in the water regime and habitat availability at the wetland. In terms of waterbird abundance, Rietvlei is the most important temporary vlei in the Western Cape and it ranks 16th in terms of waterbird abundance compared with all South African coastal and inland wetlands for which counts are available. In the light of Rietvlei being proclaimed a nature reserve, a conservation management plan for the area is discussed.     

Single-molecule Förster resonance energy transfer studies of RNA structure, dynamics and function

Single-molecule fluorescence microscopy experiments on RNA molecules brought to light the highly complex dynamics of key biological processes, including RNA folding, catalysis of ribozymes, ligand sensing of riboswitches and aptamers, and protein synthesis in the ribosome. By using highly advanced biophysical spectroscopy techniques in combination with sophisticated biochemical synthesis approaches, molecular dynamics of individual RNA molecules can be observed in real time and under physiological conditions in unprecedented detail that cannot be achieved with bulk experiments. Here, we review recent advances in RNA folding and functional studies of RNA and RNA-protein complexes addressed by using single-molecule Förster (fluorescence) resonance energy transfer (smFRET) technique.     

Correlating calcium binding, Förster resonance energy transfer, and conformational change in the biosensor TN-XXL

Genetically encoded calcium indicators have become instrumental in imaging signaling in complex tissues and neuronal circuits in vivo. Despite their importance, structure-function relationships of these sensors often remain largely uncharacterized due to their artificial and multimodular composition. Here, we describe a combination of protein engineering and kinetic, spectroscopic, and biophysical analysis of the Förster resonance energy transfer (FRET)-based calcium biosensor TN-XXL. Using fluorescence spectroscopy of engineered tyrosines, we show that two of the four calcium binding EF-hands dominate the FRET output of TN-XXL and that local conformational changes of these hands match the kinetics of FRET change. Using small-angle x-ray scattering and NMR spectroscopy, we show that TN-XXL changes from a flexible elongated to a rigid globular shape upon binding calcium, thus resulting in FRET signal output. Furthermore, we compare calcium titrations using fluorescence lifetime spectroscopy with the ratiometric approach and investigate potential non-FRET effects that may affect the fluorophores. Thus, our data characterize the biophysics of TN-XXL in detail and may form a basis for further rational engineering of FRET-based biosensors.     

Myocardial oxidative stress, osteogenic phenotype, and energy metabolism are differentially involved in the initiation and early progression of δ-sarcoglycan-null cardiomyopathy

Dilated cardiomyopathy (DCM) is a common cause of heart failure, and identification of early pathogenic events occurring prior to the onset of cardiac dysfunction is of mechanistic, diagnostic, and therapeutic importance. The work characterized early biochemical pathogenesis in TO2 strain hamsters lacking delta-sarcoglycan. Although the TO2 hamster heart exhibits normal function at 1 month of age (presymptomatic stage), elevated levels of myeloperoxidase, monocyte chemotactic protein-1, malondialdehyde, osteopontin, and alkaline phosphatase were evident, indicating the presence of inflammation, oxidative stress, and osteogenic phenotype. These changes were localized primarily to the myocardium. Derangement in energy metabolism was identified at the symptomatic stage (4 month), and is marked by attenuated activity and expression of pyruvate dehydrogenase E1 subunit, which catalyzes the rate-limiting step in aerobic glucose metabolism. Thus, this study illustrates differential involvement of oxidative stress, osteogenic phenotype, and glucose metabolism in the initiation and early progression of delta-sarcoglycan-null DCM.     

An abridged transition state model to derive structure, dynamics, and energy components of DNA polymerase β fidelity

We show how a restricted reaction surface can be used to facilitate the calculation of biologically important contributions of active site geometries and dynamics to DNA polymerase fidelity. Our analysis, using human DNA polymerase beta (pol β), is performed within the framework of an electrostatic linear free energy response (EFER) model. The structure, dynamics, and energetics of pol β-DNA-dNTP interactions are computed between two points on the multidimensional reaction free energy surface. "Point 1" represents a ground state activation intermediate (GSA), which is obtained by deprotonating the terminal 3'OH group of the primer DNA strand. "Point 2" is the transition state (PTS) for the attack of the 3'O(-) (O(nuc)) on the P(α) atom of dNTP substrate, having the electron density of a dianionic phosphorane intermediate. Classical molecular dynamics simulations are used to compute the geometric and dynamic contributions to the formation of right and wrong O(nuc)-P chemical bonds. Matched dCTP·G and mismatched dATP·G base pairs are used to illustrate the analysis. Compared to the dCTP·G base pair, the dATP·G mismatch has fewer GSA configurations with short distances between O(nuc) and P(α) atoms and between the oxygen in the scissile P-O bond (O(lg)) and the nearest structural water. The thumb subdomain conformation of the GSA complex is more open for the mismatch, and the H-bonds in the mispair become more extended during the nucleophilic attack than in the correct pair. The electrostatic contributions of pol β and DNA residues to catalysis of the right and wrong P-O(nuc) bond formation are 5.3 and 3.1 kcal/mol, respectively, resulting in an 80-fold contribution to fidelity. The EFER calculations illustrate the considerable importance of Arg183 and an O(lg)-proximal water molecule to pol β fidelity.     

Altered mitochondria,energy metabolism,voltage-dependent anion channel,and lipid rafts converge to exhaust neurons in Alzheimer’s disease

β-amyloid (Aβ) deposition, in the form of plaques and amyloid angiopathy, and hyper-phosphorylated tau deposition forming neurofibrillary tangles, dystrophic neurites around β-amyloid plaques and neuropil threads, are neuropathological hallmarks of Alzheimer’s disease (AD) that accumulate in the brain with disease progression. These changes are accompanied by progressive loss of synapses and nerve cell death. Progressive cognitive impairment and dementia are the main neurological deficits. In addition, there is cumulative evidence demonstrating other metabolic disturbances that impair cell function and hamper neuron viability. The main components of the mitochondria are altered: complex IV of the respiratory chain is reduced; complex V which metabolizes ADP to form ATP is oxidatively damaged and functionally altered; and voltage-dependent anion channel VDAC, a major component of the outer mitochondrial membrane that regulates ion fluxes, is damaged as a result of oxidative stress. Mitochondria are a major source of reactive oxygen species that promote oxidative damage to DNA, RNA, proteins and lipids. Protein targets of oxidative damage are, among others, several enzymatic components of the glycolysis, lipid metabolism and cycle of the citric acid that fuel oxidative phosphorylation, mitochondrial respiration and energy production. The lipid composition of lipid rafts, key membrane specializations that facilitate the transfer of substrates, and protein-protein and lipid-protein interactions, is altered as a result of the abnormally low levels of n-3 long chain polyunsaturated fatty acids (mainly docosahexaenoic acid) that increase viscosity and augment energy consumption. Abnormal lipid raft composition may also modify the activity of key enzymes that modulate the cleavage of the amyloid precursor protein to form toxic Aβ. This is further complicated by the disruption of the complex VDAC with estrogen receptor α at the caveolae which participates, under physiological conditions, in the protection against β-amyloid. Together, all these alterations converge in reduced energy production and increased energy demands in altered cells. Cell exhaustion is suggested as being a determining element to interpret impaired neuron function, reduced molecular turnover, and enhanced cell death.     

Which CIDE are you on? Apoptosis and energy metabolism

Around 1998, cell death-inducing DNA fragmentation factor-alpha (DFFA)-like effector (CIDE) proteins including CIDEA, CIDEB and CIDEC/fat specific protein 27 (Fsp27) were first identified by their sequence homology with the N-terminal domain of the DNA fragmentation factor (DFF). Indeed, in vitro analysis revealed that all three CIDE proteins are involved in apoptosis. However, recent gene-targeting studies have provided novel insights into the physiological function of CIDE proteins. Mice deficient in each CIDE protein exhibit lean phenotypes, a reduction of lipid droplet size in white adipose tissue and increased metabolic rate. Thus, all CIDE proteins play an important role in energy metabolism and lipid droplet formation. More recently, a glycoproteomics approach has shown that post-translational regulation of CIDE proteins via glycosylation modulates transforming growth factor (TGF)-beta 1-dependent apoptosis. Another recent study using mouse embryonic fibroblasts derived from CIDEA-deficient mice revealed that 5'AMP-activated protein kinase (AMPK) activity is regulated by CIDEA-mediated ubiquitin-dependent proteasomal degradation via a protein interaction with the AMPK beta subunit. Even after a decade of study, the physiological roles of CIDE proteins have still not been completely elucidated. This review aims to shed light on the novel functions of CIDE proteins and their physiological roles.     

Does nitric oxide modulate mitochondrial energy generation and apoptosis?

The physiological role of nitric oxide (NO) in the maintenance of vascular tone, in synaptic transmission and in cellular defence is now firmly established. Recent evidence indicates that NO can also affect mitochondrial function. Here, we review findings indicating that NO through its interaction with components of the electron-transport chain might function not only as a physiological regulator of cell respiration, but also to augment the generation of reactive oxygen species by mitochondria, and thereby trigger mechanisms of cell survival or death.     

Alternate energy dissipation? Phenolic metabolites and the xanthophyll cycle

The dynamics of phenolic galloylglucoses (di-, tri-, tetra- and penta-galloylglucose), flavonoids (quercitin and quercitin glycosides) and sideroxylonal were compared with that of xanthophyll cycle-dependent energy dissipation during rapid induction of chilling-dependent photo-inhibition. Pre-dawn xanthophyll cycle engagement of seedlings of Eucalyptus nitens transferred from mild nursery conditions to a low temperature controlled environment increased logarithmically during eight days of treatment. Photochemical efficiency and flavonoids decreased after four days of treatment and non-photochemical quenching after two days of treatment. Galloylglucoses and sideroxylonal decreased linearly during treatment. These results demonstrate that rapid changes in foliar phenolic levels are associated with abrupt changes in the plant environment. It is argued that under these growth-chamber conditions, the xanthophyll cycle facilitated dissipation of excess light energy, lessening the requirement for the dissipation of energy or antioxidant activity through phenolic metabolites.     

Mobilization and recovery of energy stores in traíra, Hoplias malabaricus Bloch (Teleostei, Erythrinidae) during long-term starvation and after re-feeding

In some neotropical environments, fishes often experience periods of poor food supply, especially due to extreme fluctuations in rainfall regime. The fish species that experience periods of drought such as the traíra Hoplias malabaricus (Bloch 1794), may stand up to long-term food deprivation. In this study, experiments were performed in order to determine the dynamic of utilization of endogenous reserves in this species during starvation. Adult traíra were both fasted for 30–240 days and re-fed for 30 days following 90 and 240 days of fasting. Glycogen and perivisceral fat were primary energy substrates consumed. During the first 30 days, fish consumed hepatic and muscular glycogen, without exhausting these reserves, and used lipids from perivisceral fat. Hepatic lipids were an important energy source during the first 60 days of starvation and perivisceral fat were consumed gradually, being exhausted after 180 days. Protein mobilization was noticeable after 60 days of fasting, and became the major energy source as the lipid reserves were decreased (between 90 and 180 days). Following the longest periods of food deprivation, fish had utilized hepatic glycogen again. Fish re-fed for 30 days after 90 and 240 days of fasting were able to recover hepatic glycogen stores, but not the other energy reserves.     

Alterations in lipid,amino acid,and energy metabolism distinguish Crohn’s disease from ulcerative colitis and control subjects by serum metabolomic profiling

Introduction

Biomarkers are needed in inflammatory bowel disease (IBD) to help define disease activity and identify underlying pathogenic mechanisms. We hypothesized that serum metabolomics, which produces unique metabolite profiles, can aid in this search.

Objectives

The aim of this study was to characterize serum metabolomic profiles in patients with IBD, and to assess for differences between patients with ulcerative colitis (UC), Crohn’s disease (CD), and non-IBD subjects.

Methods

Serum samples from 20 UC, 20 CD, and 20 non-IBD control subjects were obtained along with patient characteristics, including medication use and clinical disease activity. Non-targeted metabolomic profiling was performed using ultra-high performance liquid chromatography/mass spectrometry (UPLC-MS/MS) optimized for basic or acidic species and hydrophilic interaction liquid chromatography (HILIC/UPLC-MS/MS).

Results

In total, 671 metabolites were identified. Comparing IBD and control subjects revealed 173 significantly altered metabolites (27 increased and 146 decreased). The majority of the alterations occurred in lipid-, amino acid-, and energy-related metabolites. Comparing only CD and control subjects revealed 286 significantly altered metabolites (54 increased and 232 decreased), whereas comparing UC and control subjects revealed only five significantly altered metabolites (all decreased). Hierarchal clustering using significant metabolites separated CD from UC and control subjects.

Conclusions

We demonstrate that a number of lipid-, amino acid-, and tricarboxylic acid cycle-related metabolites were significantly altered in IBD patients, more specifically in CD. Therefore, alterations in lipid and amino acid metabolism and energy homeostasis may play a key role in the pathogenesis of CD.

     

The energy–water limitation threshold explains divergent drought responses in tree growth,needle length,and stable isotope ratios

Predicted increases in extreme droughts will likely cause major shifts in carbon sequestration and forest composition. Although growth declines during drought are widely documented, an increasing number of studies have reported both positive and negative responses to the same drought. These divergent growth patterns may reflect thresholds (i.e., nonlinear responses) promoted by changes in the dominant climatic constraints on tree growth. Here we tested whether stemwood growth exhibited linear or nonlinear responses to temperature and precipitation and whether stemwood growth thresholds co-occurred with multiple thresholds in source and sink processes that limit tree growth. We extracted 772 tree cores, 1398 needle length records, and 1075 stable isotope samples from 27 sites across whitebark pine's (Pinus albicaulis Engelm.) climatic niche in the Sierra Nevada. Our results indicated that a temperature threshold in stemwood growth occurred at 8.4°C (7.12–9.51°C; estimated using fall-spring maximum temperature). This threshold was significantly correlated with thresholds in foliar growth, as well as carbon (δ¹³C) and nitrogen (δ¹⁵N) stable isotope ratios, that emerged during drought. These co-occurring thresholds reflected the transition between energy- and water-limited tree growth (i.e., the E–W limitation threshold). This transition likely mediated carbon and nutrient cycling, as well as important differences in growth-defense trade-offs and drought adaptations. Furthermore, whitebark pine growing in energy-limited regions may continue to experience elevated growth in response to climate change. The positive effect of warming, however, may be offset by growth declines in water-limited regions, threatening the long-term sustainability of the recently listed whitebark pine species in the Sierra Nevada.