Mechanisms and models of the active transport of ions and the transformation of energy in intracellular compartments

Beyond the Chlorophyll Molecule, Are There Other Organic Compounds Capable of Dissociating the Water Molecule? New and Unexpected Insights

In the XVII century, researchers throughout Europe began to study the composition of the atmosphere, discerning its physicochemical properties and composition. Since then, it has been observed that the concentration of oxygen in the air around us is relatively low. Lavoisier and Priestley, in the middle of XVII century, observed that plants leaves could replenish oxygen in an impoverished atmosphere. They concluded that chlorophyll possessed the intrinsic property of dissociating the molecule from water. At the XVIII century, the systematic study of human physiology began to deepen, and it was found that the oxygen levels inside the human body were five times higher than those of the atmosphere. The explanation given was that the lung, by means of some unknown mechanism like those of the swim bladder of some fish, was able to concentrate oxygen from the atmosphere and introduce it into the bloodstream. But such a theoretical mechanism has not been found after 200 years of searching. However, there is no way to explain how the concentration of oxygen rises substantially in the tiny distance between the alveolar space and the blood capillaries of the lung. Circumstantially, we found the mechanism during an observational study about the blood vessels entering and leaving the human optic nerve: Our body has several molecules capable of dissociating the molecule from water, such as plants.

From leaves to roots: Biophysical models of transport of substances in plants

The transport processes of substances in various plant tissues are extremely diverse. However, models aimed at elucidating the mechanisms of such processes are almost absent in the literature. A unified view of all these transport processes is necessary, considering the laws of statistical physics and thermodynamics. A model of active ion transport was constructed based on the laws of statistical physics. Using this model, we traced the entire pathway of substances and energy in a plant. The pathway included aspects of the production of energy in the process of photosynthesis, consumption of energy to obtain nutrients from the soil, transport of such substances to the main organelles of all types of plant cells, the rise of water with dissolved substances along the trunk to the leaves, and the evaporation of water, accompanied by a change in the percentage of isotopes caused by different rates of evaporation. Models of ion transport in the chloroplasts and mitochondria of plant cells have been constructed. A generalized model comprising plant cells and their vacuoles was analyzed. A model of the transport of substances in the roots of plants was also developed. Based on this model, the problem of transport of substances in tall trees has been considered. The calculated concentrations of ions in the vacuoles of cells and resting potentials agreed well with the experimental data.

Chromosome-level genome assembly for the largemouth bass Micropterus salmoides provides insights into adaptation to fresh and brackish water

Largemouth bass (LMB; Micropterus salmoides) has been an economically important fish in North America, Europe, and China. This study obtained a chromosome-level genome assembly of LMB using PacBio and Hi-C sequencing. The final assembled genome is 964 Mb, with contig N50 and scaffold N50 values of 1.23 Mb and 36.48 Mb, respectively. Combining with RNA sequencing data, we annotated a total of 23,701 genes. Chromosomal assembly and syntenic analysis proved that, unlike most Perciformes with the popular haploid chromosome number of 24, LMB has only 23 chromosomes (Chr), among which the Chr1 seems to be resulted from a chromosomal fusion event. LMB is phylogenetically closely related to European seabass and spotted seabass, diverging 64.1 million years ago (mya) from the two seabass species. Eight gene families comprising 294 genes associated with ionic regulation were identified through positive selection, transcriptome and genome comparisons. These genes involved in iron facilitated diffusion (such as claudin, aquaporins, sodium channel protein and so on) and others related to ion active transport (such as sodium/potassium-transporting ATPase and sodium/calcium exchanger). The claudin gene family, which is critical for regulating cell tight junctions and osmotic homeostasis, showed a significant expansion in LMB with 27 family members and 68 copies for salinity adaptation. In summary, we reported the first high-quality LMB genome, and provided insights into the molecular mechanisms of LMB adaptation to fresh and brackish water. The chromosome-level LMB genome will also be a valuable genomic resource for in-depth biological and evolutionary studies, germplasm conservation and genetic breeding of LMB.

Active ion transport as the basis for water movement in plants

A model of active ion transport in plant root hair cells was built and can be used to independently calculate the concentration of ions inside plant cells and the resting potential on its membrane. Using the model, the maximum height to which water can be transported in plants was calculated.

Intra- and intercellular transport of substances: Models and mechanisms

Non-equilibrium-statistical models of intracellular transport are built. The most significant features of these models are microscopic reversibility and the explicit considerations of the driving forces of the process - the ATP-ADP chemical potential difference. In this paper, water transport using contractile vacuoles, the transport and assembly of microtubules and microfilaments, the protein distribution within a cell, the transport of neurotransmitters from the synaptic cleft and the transport of substances between cells using plasmodesmata are discussed. Endocytosis and phagocytosis models are considered, and transport tasks and information transfer mechanisms inside the cell are explored. Based on an analysis of chloroplast movement, it was concluded that they have a complicated method of influencing each other in the course of their movements. The role of quantum effects in sorting and control transport mechanisms is also discussed. It is likely that quantum effects play a large role in these processes, otherwise reliable molecular recognition would be impossible, which would lead to very low intracellular transport efficiency.

Automaton model of protein: Dynamics of conformational and functional states

In this conceptual paper we propose to explore the analogy between ontic/epistemic description of quantum phenomena and interrelation between dynamics of conformational and functional states of proteins. Another new idea is to apply theory of automata to model the latter dynamics. In our model protein's behavior is modeled with the aid of two dynamical systems, ontic and epistemic, which describe evolution of conformational and functional states of proteins, respectively. The epistemic automaton is constructed from the ontic automaton on the basis of functional (observational) equivalence relation on the space of ontic states. This reminds a few approaches to emergent quantum mechanics in which a quantum (epistemic) state is treated as representing a class of prequantum (ontic) states. This approach does not match to the standard protein structure-function paradigm. However, it is perfect for modeling of behavior of intrinsically disordered proteins. Mathematically space of protein's ontic states (conformational states) is modeled with the aid of p-adic numbers or more general ultrametric spaces encoding the internal hierarchical structure of proteins. Connection with theory of p-adic dynamical systems is briefly discussed.

Effect of acute salinity stress on ion homeostasis, Na+/K+-ATPase and histological structure in sea cucumber Apostichopus japonicus

Background

Sea cucumbers (Apostichopus japonicus) are an imperiled fauna exposed to a variety of environmental condition such as salinity and studies are urgently needed to assess their effects to guide aquaculture efforts. The effects of acute salinity stress on coelomic fluid osmotic pressure, ion concentrations, the activity of Na⁺/K⁺-ATPase in respiratory trees and the histological variations were measured to evaluate the salinity tolerance of sea cucumbers.

Results

Significant correlations in osmotic pressure were observed between coelomic fluid and ambient environmental salinity. In coelomic fluid, Na⁺ concentration was observed fluctuated during salinity 18 psu and the inflection point presented at the 6 h. The Na⁺/K⁺-ATPase activity in respiratory trees indicated the “U-shaped” fluctuant change and the change trend was opposite with the Na⁺ concentration. The ions (K⁺, Cl⁻) concentration decreased and showed the same tendency at salinity 40 psu with salinity 18 psu. The total coelomocytes counts and phagocytosis of coelomic fluid Na⁺/K⁺-ATPase activity indicated fluctuating changes under different salinity stress. Histological variation revealed a negative relation between decreasing salt concentration and tissue integrity. Tissue damages were significantly observed in intestines, muscles and tube feet under low salinity environment (18, 23 and 27 psu). The connective tissue in intestines of A. japonicus exposed to 18 and 23 psu damaged and partly separated from the mucosal epithelium. The significant variations occurred in tube feet, which presented the swelling in connective tissue and a fracture in longitudinal muscles under low salinity (18 psu). The morphological change of tube feet showed the shrinkage of connective tissue under high salinity (40 psu). The amount of infusoria in the respiratory trees decreased or even disappeared in salinity treatment groups (18 and 23 psu).

Conclusion

The results inferred that osmoconformity and ionoregulation were seen in sea cucumbers, which contributed to understand the salinity regulatory mechanisms of A. japonicus under acute salinity stress.

A Model of Isotope Separation in Cells at the Early Stages of Evolution

The separation of the isotopes of certain ions can serve as an important criterion for the presence of life in the early stages of its evolution. A model of the separation of isotopes during their transport through the cell membrane is constructed. The dependence of the selection coefficient on various parameters is found. In particular, it is shown that the maximum efficiency of the transport of ions corresponds to the minimum enrichment coefficient. At the maximum enrichment, the efficiency of the transport system approaches ½. Calculated enrichment coefficients are compared with experimentally obtained values for different types of cells, and the comparison shows a qualitative agreement between these quantities.

Nontrivial quantum and quantum-like effects in biosystems: Unsolved questions and paradoxes

Non-trivial quantum effects in biological systems are analyzed. Some unresolved issues and paradoxes related to quantum effects (Levinthal's paradox, the paradox of speed, and mechanisms of evolution) are addressed. It is concluded that the existence of non-trivial quantum effects is necessary for the functioning of living systems. In particular, it is demonstrated that classical mechanics cannot explain the stable work of the cell and any over-cell structures. The need for quantum effects is generated also by combinatorial problems of evolution. Their solution requires a priori information about the states of the evolving system, but within the framework of the classical theory it is not possible to explain mechanisms of its storage consistently. We also present essentials of so called quantum-like paradigm: sufficiently complex bio-systems process information by violating the laws of classical probability and information theory. Therefore the mathematical apparatus of quantum theory may have fruitful applications to describe behavior of bio-systems: from cells to brains, ecosystems and social systems. In quantum-like information biology it is not presumed that quantum information bio-processing is resulted from quantum physical processes in living organisms. Special experiments to test the role of quantum mechanics in living systems are suggested. This requires a detailed study of living systems on the level of individual atoms and molecules. Such monitoring of living systems in vivo can allow the identification of the real potentials of interaction between biologically important molecules.

Quantum information and the problem of mechanisms of biological evolution

One of the most important conditions for replication in early evolution is the de facto elimination of the conformational degrees of freedom of the replicators, the mechanisms of which remain unclear. In addition, realistic evolutionary timescales can be established based only on partially directed evolution, further complicating this issue. A division of the various evolutionary theories into two classes has been proposed based on the presence or absence of a priori information about the evolving system. A priori information plays a key role in solving problems in evolution. Here, a model of partially directed evolution, based on the learning automata theory, which includes a priori information about the fitness space, is proposed. A potential repository of such prior information is the states of biologically important molecules. Thus, the need for extended evolutionary synthesis is discussed. Experiments to test the hypothesis of partially directed evolution are proposed.

A matter of life, death and diseases: mitochondria from a proteomic perspective

Mitochondria are highly ordered, integrated organelles that energize cellular activities and contribute to programmed death by initiating disciplined apoptotic cascades. This review seeks to clarify our understanding of mitochondrial structural-functional integrity beyond the resolved nuclear genome by unraveling the dynamic mitochondrial proteome and elucidating proteome/genome interplay. The roles of mechanochemical coupling between mitoskeleton and cytoskeleton and crosstalk with other organelles in orchestrating cellular outcomes are explained. The authors also review the modulation of mitochondrial-related oxidative stress on apoptosis and cancer development and the context is applied to interpret pathogenetic events in neurodegenerative disorders and cardiovascular diseases. The accumulated proteomics evidence is used to describe the integral role that mitochondria play and how they influence other intracellular organelles. Possible mitochondrial-targeted therapeutic interventions are also discussed.

Origin of the directed movement of protocells in the early stages of the evolution of life

The origin of the directed motion of protocells during the early stages of evolution was discussed. The expenditures for movement, space orientation, and reception of information about the environment were taken into consideration, and it was shown that directed movement is evolutionarily advantageous in the following cases: when opposite gradients of different resources (for example, matter and energy) are great enough and when there is a rapid change in environmental parameters. It was also shown that the advantage of directed movement strategies depends greatly on how information about the environment is obtained by a protocell.