Minor Energy Sources Research Articles

Hibernating bats may use protein stores for water balance

All hibernating bats need to eat enormous amounts of food during autumn to build up a substantial fat store for hibernation. These large fat stores supply the immense amount of energy needed to survive without access to food and water. However, little is known about how the breakdown of proteins from muscles and organs contribute to the hibernating animal's energy stores and possibly their water budget. Liam McGuire from Texas Tech University, USA (now at the University of Waterloo, Canada), and colleagues from Montanan State University, Texas Tech University and the Wildlife Conservation Society, all in the USA, set out to investigate how proteins from the muscles and organs of two species of bats are used for energy and water during hibernation.In October 2016, before the bats entered hibernation, the team observed 184 cave myotis (Myotis velifer) in a cave in Oklahoma, taking measurements of the animals’ forearm length (a measurement of body size), determining their sex and using a mobile laboratory to measure the amount of fat, muscle and organ masses. Next, the team collected the same measurements from 65 Townsend's big-eared bats (Corynorhinus townsendii) at two caves in eastern Nevada during both the fall and winters of 2017–2019 to track changes in the fat, muscle and organ masses as the animals hibernated. Then, the team calculated the amount of energy and water generated by the Townsends’ big-eared bats from the decreases in fat, muscle and organ mass.McGuire and colleagues found that prior to entering hibernation, muscle and organ masses in the cave myotis was ∼25–38% of the animals’ total body mass. The team suspect that during this period, the bats build up their digestive organs to allow them to binge and build up their fat reserves in addition to bulking up their muscles to carry the large fat store. However, larger muscles and organs also provide bats with access to protein throughout hibernation. In addition, the males had proportionally larger muscles and organs, whereas the females had more body fat, which the researchers suggested may be due to differences in the animals’ reproduction strategies. Females need to conserve energy reserves throughout hibernation in preparation for possible pregnancies following hibernation. With their larger protein stores, the males have greater flexibility when arousing from hibernation to burn through organs and muscle to fuel their energy and water requirements, as protein breakdown produces more water compared to fat. But how did the hibernating big-eared bat reserves hold during their long hibernations?The males consumed approximately twice the amount of muscle and organ tissue than the females, accounting for 35% of the males’ total body mass loss and contributing 7% of the energy they used during hibernation. The females, however, had more body fat and were able to generate more energy as fat produces larger amounts of energy relative to protein. The researchers calculated how much water the animals generate as they both broke down muscle and organs and discovered that, after they subtracted the additional water that the animals lost excreting the toxic waste products generated by consuming protein, the female bats benefited by retaining four times more of the water they generated than the males. The team argues that bats could potentially use protein breakdown for hydration during hibernation.McGuire and colleagues have successfully shown that bats build up their muscles and organs prior to hibernation, which could be used as a minor source of energy but could also play a major role in the production of water. Relatively little is known about how hibernating bats using protein as a source of water, but this new study opens the flood gates to new avenues in bat hibernation research.

Gasification of Cashew Nut Shell Using Gasifier Stovein Mozambique

Mozambique relies on wood biomass for meeting its household energy demand. This has been for long referred to as one of the main causes of the ongoing deforestation, mainly around the large cities and village. On the other hand, the country produces large quantities of agricultural crops residue which are still not being appropriately and integrally used as additional source of energy, especially for communities in the countryside where these residues are generated. Cashew nut shells (CNS) are among those residues. This kind of feedstock is said to be of high energy content. However, its utilization as energy source within the country is still poor.In Mozambique, 90% of the households depend on biomass for cooking. Biomass has already emerged in the renewable energy area as one of the promising candidates for the future energy source. Historically, biomass has been a major source of fuel from the existence of making rapid urbanization, but widespread use of fossil fuels in the industrialization has relegated it to a minor source of energy. The CNS Gasifier Stove developed has a thermal efficiency of 35.5% and an energy output of 2.19 kW. The corresponding values for LPG stove and Kerosene stove are 53.53% (0.69 kW) and 39.3% (0.6 kW), respectively. Though the use of CNS gasifier as a fuel is less efficient than the aforementioned one, with the rising oil prices and the search for alternatives to contemporary cooking fuels, it is still a viable alternative in this comparison.

Maximal Aerobic and Anaerobic Power Generation in Large Crocodiles versus Mammals: Implications for Dinosaur Gigantothermy

Inertial homeothermy, the maintenance of a relatively constant body temperature that occurs simply because of large size, is often applied to large dinosaurs. Moreover, biophysical modelling and actual measurements show that large crocodiles can behaviourally achieve body temperatures above 30°C. Therefore it is possible that some dinosaurs could achieve high and stable body temperatures without the high energy cost of typical endotherms. However it is not known whether an ectothermic dinosaur could produce the equivalent amount of muscular power as an endothermic one. To address this question, this study analyses maximal power output from measured aerobic and anaerobic metabolism in burst exercising estuarine crocodiles, Crocodylusporosus , weighing up to 200 kg. These results are compared with similar data from endothermic mammals. A 1 kg crocodile at 30°C produces about 16 watts from aerobic and anaerobic energy sources during the first 10% of exhaustive activity, which is 57% of that expected for a similarly sized mammal. A 200 kg crocodile produces about 400 watts, or only 14% of that for a mammal. Phosphocreatine is a minor energy source, used only in the first seconds of exercise and of similar concentrations in reptiles and mammals. Ectothermic crocodiles lack not only the absolute power for exercise, but also the endurance, that are evident in endothermic mammals. Despite the ability to achieve high and fairly constant body temperatures, therefore, large, ectothermic, crocodile-like dinosaurs would have been competitively inferior to endothermic, mammal-like dinosaurs with high aerobic power. Endothermy in dinosaurs is likely to explain their dominance over mammals in terrestrial ecosystems throughout the Mesozoic.

Influence of stream–floodplain biogeochemical linkages on aquatic foodweb structure along a gradient of stream size in a tropical catchment

We measured nutrients and dissolved organic matter (DOM) in surface water and floodplain sediments to evaluate biogeochemical linkages between streams and floodplains in 3 streams of increasing size in a tropical catchment in northwestern Australia. We hypothesized that stream–floodplain biogeochemical connectivity, measured as similar DOM concentrations and spectroscopic properties of streamwater and floodplain sediment leachate, would decrease with increasing stream size. We expected decreasing connectivity to shift support of aquatic foodweb structure from mainly allochthonous C in small streams to algal C in larger streams. Streamwater and sediment leachate concentrations of NH4-N, NO3-N, soluble reactive P, and DOM varied several-fold across the 3 sites but showed no strong pattern in stream–floodplain connectivity with increasing stream size. Fluorescence index, specific ultraviolet absorbance, and δ13C-dissolved organic C (DOC) for stream water and sediment leachate were most similar to each other at the mid-size Adcock River, indicating tight river–floodplain biogeochemical connectivity via input of allochthonous DOM and NH4-N to stream water. δ13C and δ15N signatures for key producers and consumers for all 3 streams showed that invertebrate consumers probably were supported by a range of in-stream (e.g., benthic and filamentous algae) and floodplain (allochthonous leaf litter) sources, whereas fish strongly reflected δ13C-enriched sources (e.g., benthic algae). Allochthonous C was probably only a minor energy source for metazoa, but we propose that river–floodplain biogeochemical linkages may be important for other aspects of ecosystem productivity, such as input of inorganic nutrients to support in-stream primary production. Terrestrial–aquatic biogeochemical linkages may be critical but poorly quantified components of river–floodplain ecosystems.

Geochemical energy sources for microbial primary production in the environment of hydrothermal vent shrimps

At deep-sea hydrothermal vents, dense invertebrate communities prevail along chemoclines where the relaxation of redox-disequilibria sustains chemolithoautotrophic microbial CO2-fixation. At the Mid-Atlantic Ridge, swarms of thousands of Rimicaris exoculata shrimps thus assemble along the turbulent mixing interface between the hydrothermal fluid and oxygenated seawater. It was suggested that this environment provides ideal conditions for growth to the abundant chemosynthetic microbial epiflora that colonizes the shrimps' branchial cavity. Sulfide has long been considered as the prime electron donor used by the epibionts but, the oxidation of iron has recently been hypothesized as an alternative pathway for the iron-rich Rainbow site. In order to examine the potential energy sources for microbial primary production within the swarms at Rainbow, the chemical conditions along the mixing gradient have been modeled from field data. This model provides a basis for the quantitative comparison of energy-budgets available for chemolithoautotrophic primary production based on different oxidative pathways (e.g.: oxidation of sulfide-iron II-methane and hydrogen by oxygen). A comparison was proposed for TAG, another hydrothermal vent field at the mid-Atlantic Ridge which is characterized by the presence of similar swarms. Although the narrow temperature range of the shrimp environment is similar at both sites, their chemically contrasted environments suggest different metabolic pathways would benefit from the highest energy budgets. While sulfide oxidation is confirmed to be the energetically most favorable pathway at TAG, an original biogeochemical context is suggested for Rainbow. Here, the highest energy could be derived from iron oxidation. At this site, the oxidation of hydrogen possibly constitutes another dominant energy source, but this hypothesis still needs to be constrained by kinetic studies. Methane and sulfide appears as minor energy sources in the environment of shrimps. A wider and original diversity of the metabolic pathways involved in the microbial epibiosis can be expected at Rainbow in comparison to TAG.

HAGFISH IN THE NEW ZEALAND FJORDS ARE SUPPORTED BY CHEMOAUTOTROPHY OF FOREST CARBON

Forest litter is often considered to be a minor energy source to marine communities due to its refractory nature. Large volumes of forest litter are deposited in the New Zealand fjords, and likely recycled into available energy by microbial activity. In this study we used evidence from stable isotope analyses to test whether recycled carbon from chemoautotrophs was an important contributor to the diet of hagfish (Eptatretus cirrhatus). We then analyzed fatty acid biomarkers from the chemoautotrophic clam Solemya parkinsoni and E. cirrhatus to further discriminate the contribution of marine, terrestrial, and chemoautotrophic sources. Bulk isotopic signatures of E. cirrhatus varied considerably (delta13C, from -29.2 per thousand to -16.7 per thousand; delta15N, from -2.8 per thousand to +15.5 per thousand; delta34S, from -21.7 per thousand to +16.7 per thousand) and indicated that a significant percentage of organic matter (38-51%) originated from chemoautotrophs (delta13C, -31.3 per thousand +/- 0.1 per thousand [mean +/- SE]; delta15N, -5.7 per thousand +/- 0.2 per thousand; delta34S, -32.per thousand +/- 3.8 per thousand). Fatty acid biomarkers were depleted in 13C, particularly cis-vaccenic acid (18:1omega7: delta13C, -39.0 per thousand) indicating specific microbial origins of carbon. A high proportion of forest litter in sediments, coupled with isotopic and fatty acid biomarker results, indicates that terrestrial organic matter is a dominant contributor to this marine benthic system. This study demonstrates a clear linkage between terrestrial and marine ecological processes.

Model thermal response to minor radiative energy sources and sinks in the middle atmosphere

This paper presents the thermal response of the Canadian middle atmosphere model (CMAM) to minor radiative energy sources and sinks. These include chemical heating, infrared (IR) H2O cooling, sphericity effect in solar heating, and solar heating in the near‐IR CO2 bands. All of these energy sources/sinks can be considered as minor ones either in terms of their magnitude or in terms of the limited height region where they are of importance or both. To examine the thermal response of the middle atmosphere, a version of the CMAM with an interactive gas phase chemistry scheme has been used in a series of multiyear experiments for conditions of perpetual July. Each of the analyzed mechanisms may provide a noticeable contribution into the model energy balance that results in a statistically significant model response. Various forcing terms due to minor energy sources/sinks have different spatial and temporal distributions. Their magnitudes vary from tenths K d−1 for the sphericity effect up to ∼10 K d−1 for chemical heating that provides corresponding thermal responses of a few to about 20 K in the middle atmosphere. The model thermal response depends on the magnitude of the applied forcing but is not always local and can be spread beyond the regions where the forcing terms are initially applied. On a globally averaged basis the local strength of the model response is nearly proportional to the magnitude of the small forcing terms but shows nonlinearity when forcing due to chemical heating exceeds ∼1 K d−1 in the mesosphere. Accounting for the combined effects of the minor energy sources and sinks leads to a better agreement between the model temperature field and observations.

Early childhood feeding practices in southern Italy: is the Mediterranean diet becoming obsolete? Study of 450 children aged 6‐32 months in Campania, Italy

With increasing affluence, the traditional food choices of Mediterranean populations are changing. The changes appear to begin in early infancy, with increased consumption of processed foods. To determine current consumption patterns of the diets of 450 toddlers, 6–32 months old, enrolled from 17 paediatric practices in the Campania region of Italy, quantitative data were collected for 7 d, using calibrated feeding bottles, cups and dishes. Automated food analysis was employed and quality control was performed on a sub‐sample. The average daily intake was 373 kJ/kg. Forty‐three percent of energy was provided by carbohydrates, while fats supplied 39%, 45% of fats were saturated and 46.7% were monosaturated (primarily olive oil). Proteins provided 18% of daily energy; most (81.4%) were of animal origin. Fibre was virtually absent from the study children's diet. Total daily cholesterol reached an average value of 191 mg/d, corresponding to 201 mg/4.2 mJ. The intake per kg of cholesterol increased with age in the first year, while proteins and fats decreased. Dairy products were the main source of energy, fats and cholesterol. Vegetables and legumes were a minor source of energy at all ages: the consumption of fruit decreased with age. Although the overall pattern of feeding of this cohort remains favourable compared with other children groups in developed countries, consumption of whole milk and full fat dairy products may be reduced to equilibrate the diet.

Early childhood feeding practices in southern Italy: is the Mediterranean diet becoming obsolete? Study of 450 children aged 6-32 months in Campania, Italy. Cultural Paediatric Association.

With increasing affluence, the traditional food choices of Mediterranean populations are changing. The changes appear to begin in early infancy, with increased consumption of processed foods. To determine current consumption patterns of the diets of 450 toddlers, 6-32 months old, enrolled from 17 paediatric practices in the Campania region of Italy, quantitative data were collected for 7 d, using calibrated feeding bottles, cups and dishes. Automated food analysis was employed and quality control was performed on a sub-sample. The average daily intake was 373 kJ/kg. Forty-three percent of energy was provided by carbohydrates, while fats supplied 39%, 45% of fats were saturated and 46.7% were monosaturated (primarily olive oil). Proteins provided 18% of daily energy; most (81.4%) were of animal origin. Fibre was virtually absent from the study children's diet. Total daily cholesterol reached an average value of 191 mg/d, corresponding to 201 mg/4.2 mJ. The intake per kg of cholesterol increased with age in the first year, while proteins and fats decreased. Dairy products were the main source of energy, fats and cholesterol. Vegetables and legumes were a minor source of energy at all ages: the consumption of fruit decreased with age. Although the overall pattern of feeding of this cohort remains favourable compared with other children groups in developed countries, consumption of whole milk and full fat dairy products may be reduced to equilibrate the diet.

IRAS observations of dust heating and energy balance in the Rho Ophiuchi dark cloud

The equilibrium process dust emission in the Rho Ophiuchi dark cloud is studied. The luminosity of the cloud is found to closely match the luminosity of the clouds's known embedded and external radiation sources. There is no evidence for a large population of undetected low-luminosity sources within the cloud and unknown external heating is also only a minor source of energy. Most of the cloud's luminosity is emitted in the mid-to-far-IR. Dust temperature maps indicate that the dust is not hot enough to heat the gas to observed temperatures. A simple cloud model with a radiation field composed of flux HD 147889, S1, and Sco OB2 associations predicts the observed IRAS 60 to 100 micron in-band flux ratios for a mean cloud density n(H2) = 1400. Flattened 12 and 25 micron observations show much extended emission in these bands, suggesting stochastic heating of very small grains or large molecules.

Influence of exercise on urea, creatinine, and 3-methylhistidine excretion in normal human subjects.

To evaluate the effects of exercise on net protein catabolism, the losses of urea in sweat and urine and urinary creatinine and 3-methylhistidine (3MH) excretion were determined in eight healthy subjects during cycle ergometer exercise performed at approximately 45% of VO2max for 90 min. The subjects ingested a meat-free diet for 5 days starting 3 days before and continuing for 1 day after the day of exercise. During exercise, total urea excretion (urine + sweat losses) increased 100% above pre- and postexercise values. Thirty percent of the total urea excretion during exercise was in the form of sweat losses. Total protein breakdown (as reflected by urea excretion), however, could account for less than 5% (21 +/- 4 kcal) of total calorie expenditure during the exercise (567 +/- 83 kcal). Urinary creatinine excretion increased by 50% during exercise. Urinary excretion of 3MH also tended to rise, but the ratio of urinary 3MH to creatinine showed no change in response to exercise. We conclude that 1) light to moderate exercise results in an increase in net protein catabolism and an increase in creatinine excretion; 2) sweat losses are an important route for urea excretion during exercise; 3) there is no evidence of a disproportionate increase in breakdown of myofibrillar contractile proteins; and 4) in spite of the increase in the rate of protein catabolism, protein is only a minor source of energy during light to moderate exercise.

Comparison of the enzymatic activities of homologous muscles of flying and flightless beetles

1. 1. Activity levels of the enzymes actomyosin ATPase, phosphorylase, succinic dehydrogenase, 3-hydroxyacyl-CoA dehydrogenase, proline dehydrogenase, sarcoplasmic l-glycerol-3-phosphate dehydrogenase, pyruvate kinase and fructose-1, 6-diphosphatase were determined in homogenates of the tergocoxal muscle of the flightless beetle, Anthia thoracica, and of the tergocoxal and dorsal longitudinal muscle of Pachynoda sinuata, a normal flier. 2. 2. Actomyosin ATPase and phosphorylase activities in the muscles of P. sinuata were 2.5- and 18-fold greater than in the muscle of A. thoracica, respectively. The low phosphorylase activity and glycogen content of the latter suggest that glycogenolysis is a minor source of energy for contraction. 3. 3. The activities of succinic, proline, and glycerol-3-phosphate dehydrogenases were 4-15-fold greater in P. sinuata than in A. thoracica, but the 3-hydroxyacyl-CoA dehydrogenase activities were the same, indicating that fatty acid oxidation is the primary source of ATP in A. thoracica muscle. 4. 4. Electron microscopy showed that the tergocoxal muscle of A. thoracica was afibrillar while the muscles of P. sinuata were fibrillar. 5. 5. It is concluded that evolutionary adaptation to the flightless state results in transition of homologous muscles from a fibrillar to an afibrillar muscle type and from a primarily aerobic glycogen-based energy metabolism to one mainly dependent on fatty acid oxidation.

Fuel from Wastes: A Minor Energy Source

Fuel from Wastes: A Minor Energy Source