A prebiotic basis for ATP as the universal energy currency

ATP is universally conserved as the principal energy currency in cells, driving metabolism through phosphorylation and condensation reactions. Such deep conservation suggests that ATP arose at an early stage of biochemical evolution. Yet purine synthesis requires six phosphorylation steps linked to ATP hydrolysis. This autocatalytic requirement for ATP to synthesize ATP implies the need for an earlier prebiotic ATP-equivalent, which could drive protometabolism before purine synthesis. Why this early phosphorylating agent was replaced, and specifically with ATP rather than other nucleotide triphosphates, remains a mystery. Here we show that the deep conservation of ATP reflects its prebiotic chemistry in relation to another universally conserved intermediate, acetyl phosphate, which bridges between thioester and phosphate metabolism by linking acetyl CoA to the substrate-level phosphorylation of ADP. We confirm earlier results showing that acetyl phosphate can phosphorylate ADP to ATP at nearly 20 % yield in water in the presence of Fe3+ ions. We then show that Fe3+ and acetyl phosphate are surprisingly favoured: a panel of other prebiotically relevant ions and minerals did not catalyze ADP phosphorylation; nor did a number of other potentially prebiotic phosphorylating agents. Only carbamoyl phosphate showed some modest phosphorylating activity. Critically, we show that acetyl phosphate does not phosphorylate other nucleotide diphosphates or free pyrophosphate in water. The phosphorylation of ADP monomers seems to be favoured by the interaction between the N6 amino group on the adenine ring with Fe3+ coupled to acetyl phosphate. Our findings suggest that the reason ATP is universally conserved across life is that its formation is chemically favoured in aqueous solution under mild prebiotic conditions.

Polygonal patterns of cyclones on Jupiter: Convective forcing and anticyclonic shielding

From its unique pole-to-pole orbit, the Juno spacecraft discovered cyclones arranged in polygonal patterns around the poles of Jupiter. In a related modeling study the stability of the pattern depends on shielding -- a ring of anticyclonic vorticity surrounding each cyclone. Without shielding the vortices merge. Here we present high-resolution measurements obtained by tracking clouds in sequences of infrared images. There is vorticity of both signs at 200-km scales. The standard deviation is 0.32 times the vorticity of a large cyclone, whose relative vorticity is 0.46 times the planetary vorticity. Shielding exists at large scales, and it has the magnitude and distance from the vortex center predicted in the model. There is horizontal divergence of both signs at 200-km scales, with standard deviation 0.64 times the vorticity standard deviation. We propose that these intense structures are convection and that convection is the principal energy source for the large vortices.

Ontogenetic change in the diet of Semaprochilodus insignis (Characiformes: Prochilodontidae) during migration between two limnologically distinct environments in the Amazon Basin

Semaprochilodus insignis is an Amazonian migratory fish species, moving in large shoals between white- and black-water rivers. It has long been classified as a detritivorous fish. However, it is possible that the trophic plasticity of S. insignis could be higher than previously assumed. The objective of this study was to investigate the relative contributions of autotrophic energy sources to the diet of S. insignis in the Negro and Solimões rivers and to determine if the species undergoes an ontogenetic change in the diet. We found variations between the δ13C and δ15N values of S. insignis between the rivers. In the Negro River, periphyton (84%) was the principal energy source for adults, while juveniles in the Solimões River foraged predominantly on terrestrial plants/C3 macrophytes (50%) and phytoplankton (42%). These variations in isotopic signatures are likely associated with migratory movements of S. insignis at different life stages and hydrological periods. Instead of the previously assumed dietary classification, we suggest that S. insignis varies its diet ontogenetically, with adults acting as illiophagous in black-water while the young are detritivorous in white-water rivers. The results show that this species creates complex links between food chains, thus emphasizing the importance of conserving flooded areas.

Neurocognitive Effects of Exogenously Administered Βeta-Hydroxybutyrate In Adults: A Proof of Concept Study

βeta-hydroxybutyrate (BHB) is a ketone body produced by the liver in a process known as ketosis, as an alternative fuel source during fasting or carbohydrate caloric restriction, and is readily used as fuel throughout the body, including in the brain. While glucose is the brain’s principal energy source, when limited, ketones derived from fats become the major energy substrate. Exogenous BHB is safe to administer orally and can enhance energy and physical performance. While the literature suggests cognitive and/or behavioural performance improvement in animal models following elevation in ketones, and in clinical human samples such as those with Mild Cognitive Impairment, Alzheimer’s disease, epilepsy, and severe traumatic brain injury, the literature investigating the neurocognitive effects of exogenous administration of ketones in nonclinical, healthy samples remains limited. For this proof of concept, we present twelve subjects who underwent exogenous administration of 11.7 g of BHB. After ingestion, participants performed significantly better in attentional accuracy compared to pre-intervention scores (p < 0.05; d = 0.65), demonstrating that exogenous administration of BHB may have positive effects on the attentional accuracy domain of neurocognition in neurotypical adults. Further analysis and its clinical implications are discussed.

A new formulation of pet’s food product using by-Products from commercial tuna cannery : Physicochemical caracterization, and DLC determination

Background : Tunisia has natural resources favorable to fishing with a coastline that extends for a total length of 1,300 kilometres. The large quantities processed show that tuna canneries generate an important amounts of discarded high quality species. These wastes are, of course, problems, but they also offer excellent opportunities for biotechnological exploitation. The disposal of these wastes has always been expansive and has often a harmful impact on the environment, but thanks to the evolution of techniques and the development of markets, it is now possible to transform this waste stream into useful and marketable products. Results: In the present work, we focused primary on the characterization of the red muscles of a tuna cannery for inclusion in the formulation of young dog’s wet food. The composition of these co-products indicates a high protein content (80%), and a moderate fat and mineral content (11% and 8%, respectively). Nevertheless, the carbohydrate content in the red muscles of this fish remains low (2%). To increase the carbohydrate content whish constitute the principal energy source and fiber proportion to improve product digestibility by the animals, cereals (maize flour and rice flour) were used. Four formulae were tested, using the same manufacturing process. thA physicochemical study of the finished products was carried out and the Limit Date of Consumption was determined and estimated to 3 years and 3 months. Microbiological analyses were carried out to ensure the safety of the finished product and the results showed the absence of pathogens and the compliance of the product with current standards. Conclusion: Thanks to their high protein content, tuna discarded products represent an important source for the development of a new animal feed product, including the young dog.

Mitochondrial F-ATP Synthase and Its Transition into an Energy-Dissipating Molecular Machine

The mitochondrial F-ATP synthase is the principal energy-conserving nanomotor of cells that harnesses the proton motive force generated by the respiratory chain to make ATP from ADP and phosphate in a process known as oxidative phosphorylation. In the energy-converting membranes, F-ATP synthase is a multisubunit complex organized into a membrane-extrinsic F1 sector and a membrane-intrinsic FO domain, linked by central and peripheral stalks. Due to its essential role in the cellular metabolism, malfunction of F-ATP synthase has been associated with a variety of pathological conditions, and the enzyme is now considered as a promising drug target for multiple disease conditions and for the regulation of energy metabolism. We discuss structural and functional features of mitochondrial F-ATP synthase as well as several conditions that partially or fully inhibit the coupling between the F1 catalytic activities and the FO proton translocation, thus decreasing the cellular metabolic efficiency and transforming the enzyme into an energy-dissipating structure through molecular mechanisms that still remain to be defined.

Energetic optimization of the chilled water systems operation at hotels

The hotel exploitation, while continuing to satisfy the customers, needs to decrease the requests of electric power as the principal energy carrier. Solving issues regarding the occupation of a hotel integrally, taking the air conditioning as center of attention, which demands the bigger consumptions of electricity, results in a complex task. To solve this issue, a procedure was implemented to optimize the operation of the water-chilled systems. The procedure integrates an energy model with a strategy of low occupation following energetic criteria based on combinatorial-evolutionary criteria. To classify the information, the formulation of the tasks and the synthesis of the solutions, a methodology of analysis and synthesis of engineering is used. The energetic model considers the variability of the local climatology and the occupation of the selected rooms, and includes: the thermal model of the building obtained by means of artificial neural networks, the hydraulic model and the model of the compression work. These elements allow to find the variable of decision occupation, performing intermediate calculations to obtain the velocity of rotation in the centrifugal pump and the output temperature of the cooler water, minimizing the requirements of electric power in the water-chilled systems. To evaluate the states of the system, a combinatorial optimization is used through the following methods: simple exhaustive, stepped exhaustive or genetic algorithm depending on the quantity of variants of occupation. All calculation tasks and algorithms of the procedure were automated through a computer application.

Integration of ChREBP-Mediated Glucose Sensing into Whole Body Metabolism

Since glucose is the principal energy source for most cells, many organisms have evolved numerous and sophisticated mechanisms to sense glucose and respond to it appropriately. In this context, cloning of the carbohydrate responsive element binding protein has unraveled a critical molecular link between glucose metabolism and transcriptional reprograming induced by glucose. In this review, we detail major findings that have advanced our knowledge of glucose sensing.