Increased Energy Availability Research Articles

Diapause-associated metabolic traits reiterated in long-lived daf- 2 mutants in the nematode Caenorhabditis elegans

The longevity of the Caenorhabditis elegans diapausal dauer larva greatly exceeds that of the adult. Dauer formation and adult ageing are both regulated by insulin/IGF-1 signaling (IIS). Reduced IIS, e.g. by mutation of the daf- 2 insulin/IGF-1 receptor gene, increases adult lifespan. This may reflect mis-expression in the adult of dauer longevity-assurance processes. Since IIS plays a central role in the regulation of metabolism, metabolic alterations shared by dauer larvae and daf- 2 adults represent candidate mechanisms for lifespan determination. We have conducted a detailed comparison of transcript profile data from dauers and daf- 2 mutant adults, focusing on expression of metabolic pathway genes. Our results imply up-regulation in both dauers and daf- 2 mutant adults of gluconeogenesis, glyoxylate pathway activity, and trehalose biosynthesis. Down-regulation of the citric acid cycle and mitochondrial respiratory chain occurs in dauers, but not daf- 2 adults. However, the F 1 ATPase inhibitor was up-regulated in both, implying enhanced homeostasis in conditions where mitochondria are stressed. Overall, the data implies increased conversion of fat to carbohydrate, and conservation of ATP stocks in daf- 2 mutant adults, suggesting a state of increased energy availability. We postulate that this fuels increased somatic maintenance activity, as suggested by the disposable soma theory.

Resources and global avian assemblage structure in forests

AbstractExplaining spatial variation in a number of bird species, particularly from temperate to tropical regions, has been a longstanding challenge. We test at a global scale whether species‐rich forest assemblages are associated with division of a larger resource pool, a finer division of that pool, or some combination of the two. Species richness increases with increasing assemblage abundance, biomass and energy use. As assemblage abundance, biomass and energy use increase with increasing energy availability, and as per species numbers of individuals, biomass and energy use do not decrease with increasing energy availability, we provide direct evidence that the avian species–energy relationship in forests is associated foremost with an increase in the size of the resource pool and not with a finer level of its subdivision.

Relationship of fish catch and composition to water quality in a suite of agriculturally eutrophic lakes

We examined the fish community, water quality, and morphometry of 32 agriculturally eutrophic lakes. Our purpose was to explore the relationships between eutrophication and fish catch per unit effort by weight (CPUEw) and fish community composition of the six most important species in this suite of the world's most nutrient-rich lakes. We found that the CPUEwof the sum of all species increased with lake trophic status measured as chlorophyll a (r = 0.45, p < 0.009). By dissecting total fish CPUEwinto individual species and functional groups, we found that only common carp (Cyprinus carpio) and benthivore CPUEwincreased significantly with trophic status (p < 0.03 and 0.001, respectively). Sport fish (principally piscivores) decreased as a proportion of total CPUEwby approximately 50%, while benthivores, primarily common carp, increased by approximately 80% over an increase in cholorophyll a from 10 to 100 µg·L–1. Common carp CPUEwwas correlated with and may have a negative influence on CPUEwof bluegill (Lepomis macrochirus) and black crappie (Pomoxis nigromaculatus) and a positive influence on white crappie (Pomoxis annularis). Our study suggests that species other than benthivores may be unable to exploit increased energy availability in hypereutrophic systems or are competitively excluded from using this increased production.

Effects of cyproheptadine clorhydrate ,a serotonin receptor antagonist ,on endocrine parameters in weight-loss related amenorrhea

The aim of the study was to evaluate the possible interactions and/or modulations of the serotoninergic system on hormonal parameters and the reproductive axis in amenorrheic subjects. Hypogonadotropic,underweight ,amenorrheic patients (n = 8) were studied before and during cyproheptadine clorhydrate administration (4 mg/day for 3 months). A pulsatility study (4 hours ,sampling every 10 minutes) and analoxone test were performed before and after 4 and 12 weeks of treatment. Plasma luteinizing hormone (LH) ,follicle-stimulating hormone (FSH) ,growth hormone (GH) ,estradiol ,thyroid-stimulating hormone(TSH) ,free tri-iodothyronine (fT3) ,free thyroxine (fT4) and total triiodothyonine (total T3) ,insulin-like growth factor-I (IGF-I) concentrations were determined. Pulsedetection analysis was performed using the DETECT program.Serotoninergic receptor blockade affected neither the naloxone-inducted LH response nor the gonadotropin pulsatile parameters. Body mass index(BMI) did not vary; conversely ,integrated mean gonadotropins ,GH and fT3 concentrations increased during the treatment. In conclusion ,cyproheptadine administration affects some of the abnormalendocrine parameters of underweight amenorrheic subjects with no modulation of the opioidergic system. It is likely that the gonadotropin and the fT3 increases take place owing to a change inthe metabolic signals modulating hypothalamic function and/or an increased energy availability. Our study suggests a specific central effect of cyproheptadine on the serotonergic pathway controlling foodintake at the hypothalamic level.

Food availability affects behavior but not circulating gonadal hormones in maternal Belding's ground squirrels

We tested predictions of hypotheses suggesting that the steroid hormones, testosterone (T), progesterone (P), and estradiol (E 2), contribute to the energetic regulation of behaviors associated with rearing young in free-living female Belding's ground squirrels ( Spermophilus beldingi). We provisioned some female S. beldingi with food rich in fat and calories, and used unprovisioned females as controls. We observed the behavior of females throughout the reproductive cycle, and regularly collected blood samples to measure plasma hormone concentrations. Circulating concentrations of T, P, and E 2 were similar in provisioned and unprovisioned females, as were temporal patterns of variation in these hormones. Peaks in rates of nest maintenance and aggressive behavior occurred during gestation and were associated with elevated concentrations of circulating T, P, and E 2, raising the possibility that one or more of these hormones mediates behaviors that help females establish maternal nest sites and territories after mating. Temporal patterns of variation in behavior were similar among provisioned and unprovisioned females; however, rates of resting, vigilance, and aggression were higher among provisioned females, whereas unprovisioned females devoted significantly more time to feeding and locomotion. Thus, our data suggest that in maternal S. beldingi, gonadal steroids play a role in mediating behavior associated with raising offspring, but do not facilitate changes in rates of behavior associated with increased energy availability.

Glucose Metabolism and Milk Yield of Cows Infused Abomasally or Ruminally with Starch1,2

The effect of ruminal or abomasal starch infusion on milk yield and glucose metabolism of early lactation cows was measured. Four cows were continuously infused in the rumen or abomasum with partially hydrolyzed starch (1500 g/d) or were not infused (control) for three 14-d periods during wk 4 to 12 postpartum. Milk yield averaged over 40 kg/d throughout the experiment. Milk and milk lactose yields tended to increase when starch was infused and DMI was decreased, regardless of the site of infusion. Starch infusion increased mean insulin concentration and tended to decrease the concentration of serum nonesterified fatty acids. Ruminal starch infusion did not affect glucose irreversible loss rate but tended to increase glucagon concentration and decrease glucose oxidation. The increased milk yield that occurred when starch was infused ruminally relative to the milk yield of control cows could be a result of increased microbial protein supply or increased energy availability. Compared with ruminal starch infusion, abomasal starch infusion tended to increase the irreversible loss rate of glucose and to increase glucose oxidation. Abomasal infusion tended to increase plasma insulin concentration and to decrease the nonesterified fatty acid concentration relative to ruminal infusion. Infusion of starch abomasally resulted in increases of most uses of glucose, including milk lactose production, glucose oxidation, and the possible storage of glucose as body fat, which indicates that the early lactation dairy cow has a greater capacity for glucose metabolism than is provided by voluntary feed intake of average diets, but that not all available glucose is partitioned to the mammary gland. These data should be useful in testing current concepts and equations in nutritional and metabolic models of dairy cattle.

O-2-27 - Study of oestrogen and progestrone in meningiomas by a techniue utilizing the binding hormones in a polymerized state

The aim of this research was to investigate the influence of hydrogenated palm oil (HPO) added to a dairy goat diet on serum biochemistry and progesterone levels. Thirty pregnant Cilentana dairy goats were equally divided into 2 groups (control [CTR] and HPO groups). After kidding, concentrated feed for both groups was gradually increased up to 400 g/(animal·d), and the HPO group received 50 g/(animal·d) of HPO. Supplementation with HPO significantly increased cholesterol levels (mg/dL, 63.80 vs. 54.68 at 30 d, P ≤ 0.05; 78.20 vs. 58.00 at 60 d, P ≤ 0.05; 83.80 vs. 57.83 at 120 d, P ≤ 0.01) compared with the CTR group although no significant differences were detected for liver and kidney function indicators. Moreover, other biochemical parameters were not affected by HPO supplementation thus suggesting no change occurred in lipid and protein metabolism. Furthermore, a significant correlation was found between progesterone levels and serum cholesterol (r = 0.65, P ≤ 0.01) although these were not significantly higher in HPO supplemented goats. The dose and time of HPO supplementation appears critical as regards assessing the limits between the risks and benefits of HPO supplementation in dairy goats. At the tested dose, HPO was well tolerated by the animals and may represent a useful tool to increase energy availability during highly demanding periods.

Egg Size, Temperature and Laying Sequence: Why do Snow Geese Lay Big Eggs When it's Cold?

1. Several studies of altricial passerines ('income breeders') have shown that females lay smaller eggs when they experience low temperatures during egg formation. This is usually explained in terms of a 'physiological trade-off' : birds having to divert more of their finite resources to maintenance and away from reproduction in cold weather, although little is known about the proximate mechanism(s) underlying this phenomenon. 2. We investigated the relationship between egg size and ambient temperature during the egg formation period in the Lesser Snow Goose (Anser caerulescens caerulescens), a precocial, 'capital-breeding' species, using 10 years of data derived from a long-term population study of this species at La Perouse Bay, Man., Canada. 3. Egg size was negatively correlated with ambient temperature in the Snow Goose, i.e. females laid larger eggs when temperatures were lower during egg formation, contrasting markedly with the positive correlation reported in altricial, income-breeders. 4. The effect of temperature on egg size was most marked for last-laid eggs within a clutch (b = -0.675 g °C -1 ), and for temperatures during the last half of the rapid yolk development (RYD) period (rather than for the whole or the middle of the RYD period), as predicted by an exponential growth curve for yolk development. 5. The relationship between egg mass and temperature was time- and laying-sequence specific : for first and middle eggs the correlation was positive early in the period of RYD and negative closer to ovulation. For last-laid eggs the correlation between egg mass and temperature was negative throughout the 10 day RYD period. 6. We suggest that the different relationship between egg size and temperature in the Snow Goose, compared to passerine species, may reflect different contributions of exogenous vs endogenous reserves, and different opportunities to increase energy availability through dietary intake. 7. Although statistically significant, temperature has only a small effect on egg size in the Lesser Snow Goose : the average range of temperatures encountered would only lead to a 3-5% difference in mean egg mass. This is consistent with high heritability of egg size.

Induction of low-T3 syndrome in exercising women occurs at a threshold of energy availability

To investigate the relationship between energy availability (dietary energy intake minus energy expended during exercise) and thyroid metabolism, we studied 27 untrained, regularly menstruating women who performed approximately 30 kcal.kg lean body mass (LBM)-1.day-1 of supervised ergometer exercise at 70% of aerobic capacity for 4 days in the early follicular phase. A clinical dietary product was used to set energy availability in four groups (10.8, 19.0, 25.0, 40.4 kcal.kg LBM-1.day-1). For 9 days beginning 3 days before treatments, blood was sampled once daily at 8 A.M. Initially, thyroxine (T4) and free T4 (fT4), 3,5,3'-triiodothyronine (T3) and free T3 (fT3), and reverse T3 (rT3) were in the normal range for all subjects. Repeated-measures one-way analysis of variance followed by one-sided, two-sample post hoc Fischer's least significant difference tests of changes by treatment day 4 revealed that reductions in T3 (16%, P < 0.00001) and fT3 (9%, P < 0.01) occurred abruptly between 19.0 and 25.0 kcal.kg LBM-1.day-1 and that increases in fT4 (11%, P < 0.05) and rT3 (22%, P < 0.01) occurred abruptly between 10.8 and 19.0 kcal.kg LBM-1.day-1. Changes in T4 could not be distinguished. If energy deficiency suppresses reproductive as well as thyroid function, athletic amenorrhea might be prevented or reversed by increasing energy availability through dietary reform to 25 kcal.kg LBM-1.day-1, without moderating the exercise regimen.

Relationship of post-partum interval in mature beef cows with nutritional environment, biological type and serum IGF-1 concentrations

AbstractMature cows of nine breeds were fed (four cows per level within breed) at either 0·55, 0·71, 0·88 or 1·05 MJ metabolizable energy (ME) per kg initial body weight0·75 per day during non-lactational periods for an average of 4 years. During lactation, energy allowances were increased by 0·17 MJ ME per kg body weight0·75 per day. Breeds represented four biological types: moderate genetic potential for milk yield and growth (Angus, Hereford, Red Poll), moderate milk and high growth (Charolais, Eimousin), high milk and moderate growth (Braunvieh, Pinzgauer) and high milk and growth (Gelbvieh, Simmental). The objective was to test the effects of biological type and nutritional environment on length of post-partum interval as determined from serum progesterone levels. The potential of serum insulin-like growth factor-1 (IGF-1) level at 3 weeks post partum for predicting the length of the post-partum interval was also evaluated. Non-parametric statistical analyses appropriate for right-censored survival data were used to test effects on post-partum interval because collection of serum was terminated prior to ovulation in some cows.Energy availability × biological type effects on post-partum interval were significant. Increased energy availability tended to decrease post-partum interval in all biological types with high potential growth types exhibiting the greatest positive response to increased food. Post-partum interval for types with high growth potential was shorter within food level when associated with high rather than moderate potential for milk yield. Serum IGF-1 was related to post-partum interval at lower energy availability but appeared to have limited usefulness for identifying cows with extended intervals. Inherent direct and maternal production potential interact with available food resources to influence the post-partum interval of mature beef cows.

Effects of noncarbohydrate substrates on protein synthesis in hearts from fed and fasted rats

An overnight fast reduced RNA content and resulted in lower rates and efficiency of protein synthesis when rat hearts were perfused in vitro and supplied glucose as oxidizable substrate. Decreased efficiency of synthesis was associated with development of a block in peptide chain initiation in hearts of both fed and fasted rats. Provision of pyruvate increased the rate and efficiency of protein synthesis in fasted but not fed tissue, and partially overcame the initiation block in both groups. A mixture of glucose, pyruvate and insulin increased the efficiency of protein synthesis and decreased ribosomal subunit content to similar values in both groups of hearts. Noncarbohydrate substrates, including pyruvate, lactate, acetoacetate and beta-hydroxybutyrate, supported higher rates of protein synthesis than glucose in hearts of fasted, but not fed rats. However, mixtures of glucose and either pyruvate, acetoacetate or beta-hydroxybutyrate increased the synthetic rate in fed tissue. Provision of noncarbohydrate substrates increased energy availability, as indicated by higher creatine-P/creatine ratios in both groups of hearts, but the synthetic rate increased as a function of creatine-P/creatine ratio only in the fasted tissue. Octanoate and leucine accelerated protein synthesis and increased energy availability in the fed tissue. The mixtures of glucose and noncarbohydrate substrates or octanoate elevated glucose-6-P content. These studies indicate that an overnight fast decreased the capacity for protein synthesis and modified the regulation of synthesis by noncarbohydrate substrates.

An Energetics Simulation Model for Managing Wintering Bald Eagles

An energetics simulation model was developed to aid in the management of wintering bald eagles (Haliaeetus leucocephalus) in Washington. The model consists of 3 subroutines: (1) consumable biomass submodel, (2) energy consumption submodel, and (3) activity costs submodel. The 1st submodel predicts the quantity of chum (Oncorhynchus keta) and coho (0. kisutch) salmon biomass that potentially is usable by eagles wintering along rivers in Washington. Salmon biomass values are adjusted for the effects of edible content, competition, decomposition, and availability for use. The 2nd submodel predicts daily energy requirements and food (salmon) consumption by eagles as affected by body mass, body and ambient temperatures, wind velocity, and long-wave radiation. The 3rd submodel estimates energy costs of flight activity for both natural flight and avoidance flight from human disturbance. The model projects population energy demand, determines carrying capacity based on salmon runs, and estimates use of salmon by eagles. An example is presented for the Nooksack River in northwestern Washington. Verification of the model in predicting population density indicates less than a 19% error factor. A sensitivity analysis of the model identified management techniques to increase energy availability and to reduce energy loss by eagles. J. WILDL. MANAGE. 47(2):349-359 Population densities of wintering raptors are closely linked to food supplies (Newton 1979:80). Competition for food is suspected to be a critical limiting factor for many bald eagle populations (Swenson 1975, Sherrod et al. 1976, Stalmaster 1981b). If bald eagles are food-limited, management strategies that maximize energy availability to eagles and minimize their energy loss could increase overwinter survival. An energetics simulation model is capable of describing energy pathways, analyzing effects of environmental perturbations on population energy demand, and determining carrying capacities of wintering grounds. Manipulation of energy relationships could facilitate management of bald eagles. Model simulation of energy flow through bird populations has been conducted (Holmes and Sturges 1973, Wiens and Innis 1974, Wiens and Nussbaum 1975, Wiens and Scott 1975), but no study has used energy modeling as a basis for developing management techniques for an endangered species. Stalmaster (1981b) and Stalmaster and Gessaman (1982) described energy requirements of wintering bald eagles. The objective of this paper is to present an energetics simulation model that provides information useful for the management of bald eagle populations. I thank R. L. Knight for suggesting, supporting, and securing funds for this study. This project was supported by the Washington Department of Game. J. A. Gessaman assisted in programming the energy consumption submodel. I appreciate review comments by J. W. Grier, R. L. Knight, S. K. Knight, J. R. Koplin, and J. E. Swenson on an earlier draft of this

Energy intake and productivity of Guatemalan sugarcane cutters: An empirical test of the efficiency wage hypothesis part II

This paper examines additional evidence of an empirical test of the productivity-consumption relation of the efficiency wage hypothesis. A cross-sectional analysis showed sharply diminishing productivity returns to higher levels of daily energy intake of Guatemalan sugarcane cutters. No positive and consistent energy supplementation effect on the daily supply of work units could be demonstrated in a time-series analysis. Energy supplementation did not have a delayed impact on worker productivity. It is concluded that increased energy availability may not necessarily result in increased productivity of rural workers who are moderately energy deficient.

Energy intake and productivity of Guatemalan sugarcane cutters: An empirical test of the efficiency wage hypothesis part I

This study represents an empirical test of the productivity consumption relation of the efficiency wage hypothesis, which is briefly discussed here. The research setting and design of the study are described. An energy supplementation program was generally effective in raising the daily energy intake and energy expenditure levels of Guatemalan sugarcane workers who were moderately energy deficient. Increased energy availability did not result in increased energy expenditure at work, or in an increased supply of work units. The results do not provide evidence of a strong productive-energy intake relationship among these workers.

The choices in the next energy and social revolution

The purpose of this article is to provide a context for choosing the energy system that will replace fossil fuels. It does not pretend to answer all of the difficult problems that will be encountered in reaching equilibrium. It argues the case on physical and social grounds why solar energy, not nuclear fusion, the other possible ultimate source, provides the best alternative. Two events of unparalleled importance stand out in the long course of human history: the introduction of agriculture, and industrialization. They were profound energy and social revolutions: energy revolutions in that each vastly increased energy availability over the former period; social revolutions in that each increased the scale of society and rearranged the social order around new technologies, institutions, and values. As fossil fuels, the energy source of industrialization, are depleted, the world enters into the third most important energy and social revolution in the development of civilization. Natural and social systems operate under the same principles of energy management. Growth, stability, or decline is determined by the interdependent relationship between energy and structure (Energy in Natural and Social Systems). The evolution of civilization over more than a million years can be seen as a successful quest to control greater amounts of energy through social organization in three different energy and social systems: hunting and gathering, agriculture, and fossil fuels (Two Energy and Social Revolutions). Many nations based on different energy and social structures have flourished and disappeared throughtout history. The cases of Egypt, Rome, and Britain are used to illustrate the dynamic forces that affect the rise and fall of empires, dependence on foreign resources and the changing purposes of social organization (The Influence of Energy on Nations). The energy perspective of the paper suggests the relationship between continuous growth and social discontinuity in the United States (Continuous Growth and Social Discontinuity in the United States). The physical and social consequences of future energy alternatives are discussed in terms of an Orwellian-, Jeffersonian-, and Malthusian-type future (The Third Revolution: Orwell, Jefferson, or Malthus). The paper concludes with an endorsement of solar energy as the alternative most likely to afford a stable future in a humanly organized environment (Conclusion).