The sleep and the visceral function control

The review focuses on rapidly growing body of data indicating that disturbances of the natural sleep and sleep deprivation lead to various visceral disorders. The review mentions consequences of sleep disturbances on the gastro-intestinal system, cardio-vascular and respiratory, immune, endocrine and reproductive functions. In order to establish the functional link between the sleep and the visceral health it is proposed that during sleep the central nervous system including all cortical areas switches from the processing of the exteroceptive information to the processing of the interoceptive information. Review of the studies, which offer the direct confirmation of this hypothesis, is presented.     

Free energy of biological systems

The generalization of the Gibbs potential to open spatially inhomogeneous systems is given. This generalization is based on the abandonment of the local equilibrium hypothesis and the introduction of the specific parameters of spatial inhomogeneity: thermodynamical forces and the coordinates of useful works. The existence of the potential state function whose decrease determines the algebraic sum of useful (external) and dissipative (internal) works executed by the system was justified. This function presents the difference between the internal energy of the spatial inhomogeneous system and its homogeneous parts and was named (owing to its independence from the pathways of processes in the space of thermostatic variables) the general thermodynamic potential. It was demonstrated that the application of this potential to biological systems permits one to trace their development for each of their intrinsic degrees of freedom, to combine the thermodynamic and kinetic approaches to the problems of their evolution, to find a criterion of maturity of a biological organism and a general measure of the orderliness of the biosystem, to find the driving forces of biological processes, and confirm the possibility of development of biosystems without the equilibrium state.     

The temporal ‘structure’ and function of the insect photoperiodic clock: a tribute to Colin S. Pittendrigh

In 1936, Erwin Bünning suggested that photoperiodic time measurement was a function of the circadian system. Colin Pittendrigh became an ardent supporter of Bünning's hypothesis, drawing parallels between photoperiodism and his own group's investigations of adult eclosion rhythmicity in the fruit fly Drosophila pseudoobscura. They developed several more modern versions of Bünning's general hypothesis based on the entrainment of circadian oscillations to the light cycle, including ‘external coincidence’, which is a derivation of Bünning's original model, and ‘internal coincidence’, which relied upon seasonal changes in the mutual phase relationship of oscillators within a multi‐oscillator circadian system. This review considers the experimental evidence for the central role of the circadian system in photoperiodic timing and, in some species, for both external and internal coincidence. Pittendrigh, however, pursued the idea of internal coincidence further with his analysis of the pacemaker–slave organization of eclosion rhythmicity in D. pseudoobscura and proposed a similar theoretical model for photoperiodism comprising a group of slave oscillators driven by a light‐sensitive pacemaker. In this model, the phase relationships of the slaves to the pacemaker were affected by (i) the relative periods of the pacemaker and slave(s); (ii) the strength(s) of the coupling between the two; and (iii) the dampening coefficients of the various slaves. Manipulation of these variables showed that the slaves adopted different internal phase relationships (both to each other and to the pacemaker) under the influence of changes in daily photophase, the period of the Zeitgeber and phase shifts of the entraining light cycle.     

Relation between protein stability, evolution and structure, as probed by carboxylic acid mutations

Native proteins are marginally stable. Low thermodynamic stability may actually be advantageous, although the accumulation of neutral, destabilizing mutations may have also contributed to it. In any case, once marginal stability has been reached, it appears plausible that mutations at non-constrained positions become fixed in the course of evolution (due to random drift) with frequencies that roughly reflect the mutation effects on stability ("pseudo-equilibrium hypothesis"). We have found that all glutamate-->aspartate mutations in wild-type Escherichia coli thioredoxin are destabilizing, as well as most of the aspartate-->glutamate mutations. Furthermore, the effect of these mutations on thioredoxin thermodynamic stability shows a robust correlation with the frequencies of occurrence of the involved residues in several-hundred sequence alignments derived from a BLAST search. These results provide direct and quantitative experimental evidence for the pseudo-equilibrium hypothesis and should have general consequences for the interpretation of mutation effects on protein stability, as they suggest that residue environments in proteins may be optimized for stabilizing interactions to a remarkable degree of specificity. We also provide evidence that such stabilizing interactions may be detected in sequence alignments, and briefly discuss the implications of this possibility for the derivation of structural information (on native and denatured states) from comparative sequence analyses.     

Function and the Evolution of Phenotypic Stability: Connecting Pattern to Process

Phenotypes manifest a balance between the inherited tendencyto remain the same (phenotypic stability) and the tendency tochange in response to current environmental conditions (adaptation).This paper explores the role of functional integration and functionaltrade-offs in generating phenotypic stability by limiting theresponses of individual characters to environmental selection.Evolutionarily stable configurations (ESCs) are systems of functionallyinteracting characters within which characters are "judged"by their contribution to system-level functionality. This "internal"component of selection differs from traditional "external" selectionin that it travels with the organism wherever it goes and ismaintained across a wide range of environments. External selection,in contrast, is by definition environment-dependent. The temporaland geographic constancy of internal selection therefore actsto maintain phenotypic stability even as environments change.Functional trade-offs occur when one character participatesin more than one function, but can only be optimized for one.Participation of certain ("keystone") characters in a trade-offpotentially causes stabilization of an entire system owing toa cascade of functional dependencies on that character. Phylogeneticcharacter analysis is an essential part of elucidating theseprocesses, but patterns cannot be used as prima facie evidenceof particular processes.     

New concepts on the structure of the neuronal networks: The miniaturization and hierarchical organization of the central nervous system

The hypothesis is introduced that miniaturization of neuronal circuits in the central nervous system and the hierarchical organization of the various levels, where information handling can take place, may be the key to understand the enormous capability of the human brain to store engrams as well as its astonishing capacity to reconstruct and organize engrams and thus to perform highly sophisticated integrations. The concept is also proposed that in order to understand the relationship between the structural and functional plasticity of the central nervous system it is necessary to postulate the existence of memory storage at the network level, at the local circuit level, at the synaptic level, at the membrane level, and finally at the moIecular level. Thus, memory organization is similar to the hierarchical organization of the various levels, where information handling takes place in the nervous system. In addition, each higher level plays a role in the reconstruction and organization of the engrams stored at lower levels. Thus, the trace of the functionally stored memory (i.e. its reconstruction and organization at various levels of storage) will depend not only on the chemicophysical changes in the membranes of the local circuits but also on the organization of the local circuits themselves and their associated neuronal networks.Dedicated to Prof. R. Luft for his outstanding achievements in endocrinology and his provocative and inspiring discussions in biology.     

American Society of Biomechanics Journal of Biomechanics Award 2018: Adaptive motor planning of center-of-mass trajectory during goal-directed walking in novel environments

To aid in the successful execution of goal-directed walking (discrete movement from a start location to an end target) the central nervous system forms a predictive motor plan. For the motor plan to be effective, it must be adapted in response to environmental changes. Despite motor planning being inherent to goal-directed walking, it is not understood how the nervous system adapts these plans to interact with changing environments. Our objective was to understand how people adapt motor plans of center of mass (COM) trajectory during goal-directed walking in response to a consistent change in environmental dynamics. Participants preformed a series of goal-directed walking trials in a novel environment created by a cable robot that applied a lateral force field to their COM. We hypothesized that participants would adapt to the environment by forming an internal model of their COM trajectory within the force field. Our findings support this hypothesis. Initially, we found COM trajectory significantly deviated in the same direction as the applied field, relative to baseline (no field) (p = 0.002). However, with practice in the field, COM trajectory adapted back to the baseline (p = 0.6). When we unexpectedly removed the field, participants demonstrated after-effects, COM trajectory deviated in the direction opposite of the field relative to baseline (p < 0.001). Our findings suggest that when performing a goal-directed walking task, people adapt a motor plan that predicts the COM trajectory that will emerge from the interaction between a specific set of motor commands and the external environment.     

Corticotropin releasing hormone and its function in the skin.

The skin, as the largest organ of the body, is strategically located as a barrier between the external and internal environments, being permanently exposed to noxious stressors such as bursts of radiation (solar, thermal), mechanical energy, or chemical and biological insults. Because of its functional domains and structural diversity, the skin must have a constitutive mechanism for dealing with the stressors. Activities of the skin are mostly regulated by local cutaneous factors and stressed skin can generate signals to produce rapid (neural) or slow (humoral) responses to local or systemic levels. Thus, the skin neuroendocrine system is comprised of locally produced neuroendocrine mediators that interact with corresponding specific receptors through para- or autocrine mechanisms. Furthermore, it is known for several years that the corticotropin-releasing hormone (CRH)/ pro-opiomelanocorticotropin (POMC) skin system fulfils analogous functions to the hypothalamic-pituitary-adrenal (HPA) stress axis. Additionally, skin cells produce hormones, neurotansmitters and neuropeptides, having the corresponding receptors and the skin itself is able to fulfill a multidirectional communication between endocrine, immune and central nervous systems as well as other internal organs. In summary, the skin expresses an equivalent of the prominent hypothalamic-pituitary-adrenal stress axis that may act as a cutaneous defense system, operating as a coordinator and executor of local responses to stress, in addition to its normal function: the preservation of body homeostasis.     

Feedback and the typological characteristics of higher nervous activity]

Apparatus of the theory of automatic regulation and control systems is applied for explanation of typological characteristics of the higher nervous activity. On the basis of the analysis of activity of four types of automatic control systems a hypothesis is suggested that these characteristics are connected with organization of the feedback in the functional system, and analogies drawn between the types of the higher nervous activity and types of automatic systems.     

Non-locality in biological systems results from hierarchy

The concept of non-locality is deduced from a new concept for biological systems, the functional interaction. It is shown that a biological system, which is expressed in terms of functional interactions, can be constructed as a hierarchical system, the dynamics of which are represented by a non-local field at each level of organization. The two following constraints: continuous representation of state variables and hierarchy of the system, result in non-locality, i.e., a space property according to which the system depends on mechanisms that are located elsewhere in the space. Concepts and theory are illustrated in the case of the nervous system, where two levels of organization are considered, the level of neurons and the level of synapses. Non-local versus local field operators are discussed, and an interpretation of the field equation terms is proposed. A general formulation of non-local operators for hierarchical systems is given.     

Hormonal regulation of female reproduction

Reproduction is an event that requires the coordination of peripheral organs with the nervous system to ensure that the internal and external environments are optimal for successful procreation of the species. This is accomplished by the hypothalamic-pituitary-gonadal axis that coordinates reproductive behavior with ovulation. The primary signal from the central nervous system is gonadotropin-releasing hormone (GnRH), which modulates the activity of anterior pituitary gonadotropes regulating follicle stimulating hormone (FSH) and luteinizing hormone (LH) release. As ovarian follicles develop they release estradiol, which negatively regulates further release of GnRH and FSH. As estradiol concentrations peak they trigger the surge release of GnRH, which leads to LH release inducing ovulation. Release of GnRH within the central nervous system helps modulate reproductive behaviors providing a node at which control of reproduction is regulated. To address these issues, this review focuses on several critical questions. How is the HPG axis regulated in species with different reproductive strategies? What internal and external conditions modulate the synthesis and release of GnRH? How does GnRH modulate reproductive behavior within the hypothalamus? How does disease shift the activity of the HPG axis?     

Organization of the Nervous System and Sensory Organs in the Larva of the Marine Bryozoan Bowerbankia gracilis (Ctenostomata: Vesiculariidae): Functional Significance of the Apical Disc and Pyriform Organ

The organization of the nervous system and the histology and ultrastructure of the apical disc and the pyriform organ have been investigated by serial sections with light and electron microscopy for the larva of the vesiculariid ctenostome bryozoan Bowerbankia gracilis Leidy 1855. The nervous system consists of four major internal components: (1) a median-anterior nerve nodule; (2) an equatorial, subcoronal nerve ring; (3) paired aboral nerve cords; (4) paired antero-lateral nerve tracts. The nervous system is associated with the ciliated larval surface at the apical disc, the pyriform organ, the corona and the intercoronal cells. The paired aboral nerve cords extend from the apical disc to the nerve nodule, which gives rise to the paired antero-lateral nerve tracts to the pyriform organ and to paired lateral tracts that form the equatorial nerve ring. Ultrastructural evidence is provided for the designation of primary sensory cells in the neural plate of the apical disc and in the juxtapapillary regions of the pyriform organ. Efferent synapses are described between the equatorial nerve ring and the overlying coronal cells, which constitute the primary locomotory organ of the larva. The repertoire of potential functions of the apical disc and pyriform organ are discussed. It is concluded that the apical disc and pyriform organ constitute larval sensory organs involved in orientation and substrate selection, respectively. Their association with the major effector organs of the larva (the corona and the musculature) via the nervous system supports this interpretation.     

Alteration of the acetylcholine response by intra- and extracellular serotonin application in intracellularly perfused neurons ofLymnaea stagnalis

1. The effect of serotonin on the acetylcholine (ACh) response has been studied by means of voltage clamp and intracellular perfusion in unidentified isolated neurons from parietal and visceral ganglia of Lymnaea stagnalis. 2. In most cells studied serotonin added to the internal or external solution decreases the response to ACh. 3. In other neurons serotonin added to the intracellular solution increases the response to ACh; when it is added extracellularly it produces the opposite effect on the same cells. 4. The decreasing effect of serotonin on ACh currents is mimicked by cyproheptadine, an antagonist of serotonin receptors, and by the intracellular application of cyclic AMP (cAMP) forskolin. 5. The enhancing effect of intracellularly applied serotonin on ACh currents is blocked by cyproheptadine and is not obtained by the intracellular administration of cAMP and forskolin. In some cells the enhancing effect of serotonin appears after forskolin. 6. The results suggest a modulating effect of serotonin on cholinergic synaptic transmission in the nervous system of mollusks. The possible existence of intracellular serotonin receptors is discussed.     

Is there anything "autonomous" in the nervous system?

The terms "autonomous" or "vegetative" are currently used to identify one part of the nervous system composed of sympathetic, parasympathetic, and gastrointestinal divisions. However, the concepts that are under the literal meaning of these words can lead to misconceptions about the actual nervous organization. Some clear-cut examples indicate that no element shows "autonomy" in an integrated body. Nor are they solely "passive" or generated "without mental elaboration." In addition, to be "not consciously controlled" is not a unique attribute of these components. Another term that could be proposed is "homeostatic nervous system" for providing conditions to the execution of behaviors and maintenance of the internal milieu within normal ranges. But, not all homeostatic conditions are under the direct influence of these groups of neurons, and some situations clearly impose different ranges for some variables that are adaptative (or hazardous) in the tentative of successfully coping with challenging situations. Finally, the name "nervous system for visceral control" emerges as another possibility. Unfortunately, it is not only "viscera" that represent end targets for this specific innervation. Therefore, it is commented that no quite adequate term for the sympathetic, parasympathetic, and gastrointestinal divisions has already been coined. The basic condition for a new term is that it should clearly imply the whole integrated and collaborative functions that the components have in an indivisible organism, including the neuroendocrine, immunological, and respiratory systems. Until that, we can call these parts simply by their own names and avoid terms that are more "convenient" than appropriate.     

Development of the synganglion and morphology of the adult nervous system in the mite Archegozetes longisetosus Aoki (Chelicerata,Actinotrichida, Oribatida)

Small arthropods show a highly condensed central nervous system, which is accompanied by the loss of the ancestral metameric organization. This results in the formation of one solid mass, a synganglion. Although numerous studies investigated the morphology of Archegozetes longisetosus, the organization of the nervous system is to date unknown. Using synchrotron X‐ray microtomography, we investigated the organization of the nervous system in the adult stage and the development of the synganglion over all five free‐living life stages (larva, proto‐, deuto‐, tritonymph and adult). The general morphology of the synganglion resembles that of other studied mites (in the classic sense) and ticks, being subdivided into a sub‐ and supraesophageal region, and consisting of cortex and neuropil. All nerves entering the walking legs except the first consist of two rami. This split is not based on a functional division into a motor and a sensory ramus, but both rami contain motor and sensory neurites. Within the synganglion, we found structures that resemble the ancestral metameric organization of the nervous system of arthropods. The development of the synganglion of A. longisetosus shows a more or less linear increase in volume, but cortex and neuropil grow at different rates over the five life stages. Between the second and third nymphal stage, the volume of the neuropil increases at a faster rate than the cortex. J. Morphol. 277:537–548, 2016. © 2016 Wiley Periodicals, Inc.     

Painful interactions: Microbial compounds and visceral pain

Visceral pain, characterized by abdominal discomfort, originates from organs in the abdominal cavity and is a characteristic symptom in patients suffering from irritable bowel syndrome, vulvodynia or interstitial cystitis. Most organs in which visceral pain originates are in contact with the external milieu and continuously exposed to microbes. In order to maintain homeostasis and prevent infections, the immune- and nervous system in these organs cooperate to sense and eliminate (harmful) microbes. Recognition of microbial components or products by receptors expressed on cells from the immune and nervous system can activate immune responses but may also cause pain. We review the microbial compounds and their receptors that could be involved in visceral pain development.     

Internal apparatus of neuropil in coelomata: Reconstruction of the earlier stages of its evolution

Based on previously obtained data on structural organization and evolution of neuropil in annelids and phoronids, reconstruction of their internal apparatus has been performed. Four structural types are identified: the first—the initial, the most primitive state characteristic of neuropil of articulates (polychaetes with intraepidermal nervous system); the second—peculiar to neuropil of polychaetes in the beginning of the exit of the nervous system from epidermis; the third—the specific state of neuronal interrelations in leeches, when the internal apparatus contains no local interneurons, but is formed by intensive local arborization of associative neurons with intersegmental connections; the fourth—the initial state of the internal apparatus peculiar to Tentaculata, which is structurally incomparable with that in the primitive articulates. It has been shown that the initial state of neuronal structure of the internal apparatus of primitive polychaetes oweniids and phoronids, although has externally similar basiepidermal position, is incomparable architectonically. Therefore, at present, determination of the internal apparatus can be achieved only in general as a system of local interneurons, which provides to an extent of precision the afferent—efferent connections in neuropil and contributes to integration of these connections with the cerebropetal and cerebrofugal pathways. Complication of the internal apparatus structure in jointed Trochozoa with the ganglionic type of the nervous system has its own specific features. Four levels of its differentiation have been identified: (1) start of exit of the abdominal ganglion from epidermis (polychaetes nephthyds); (2) complete or partial exit of the nervous system form epidermis (most of polychaetes, oligochaetes); (3) replacement of local interneurons of the internal apparatus by a morphologically rearranged system of intersegmental associative neurons of the functionally similar nature (with exception of leeches, this process is typical to different extent of crustacean and arachnids); (4) intensive development of the system of local interneurons, which is peculiar to the internal apparatus of insects.Translated from Zhurnal Evolyutsionnoi Biokhimii i Fiziologii, Vol. 40, No. 6, 2004, pp. 546–555.Original Russian Text Copyright © 2004 by Lagutenko.To the 100-Anniversary of A. K. VoskresenskayaThis revised version was published online in April 2005 with a corrected cover date.     

Qualitative and quantitative insights into the 3D microanatomy of the nervous ganglia of Scrobicularia plana (Bivalvia: Tellinoidea: Semelidae)

The nervous system of bivalves is bilaterally symmetrical and consists of interconnected cerebropleural, pedal and visceral ganglia, which may be partially to totally fused. We studied the microanatomy of the ganglia of Scrobicularia plana using three-dimensional (3D) reconstruction. We also examined whether intersex differences in the neural structure exist. Each type of ganglion had a characteristic 3D shape, and the cerebropleural ganglia shape was slightly asymmetrical. The visceral, pedal and cerebropleural ganglia are progressively smaller in volume, but only the pedal ganglion volume was positively correlated with the animal’s length, height or width; suggesting functional implications. As to total surface area, correlations were found for the cerebropleural and visceral ganglia, but it was the visceral that consistently showed strong positive correlations with each biometric parameter. The medulla may often penetrate the cortex and touch the capsule in areas that (contrary to what might be expected) are not connected with emerging nerves. Despite the differences in volume and surface area among ganglia, the volume ratio of cortex/medulla is fairly stable (c. 1.5), suggesting a functional optimum. Finally, we conclude that the ganglia of males and females do not show significant quantitative differences.     

How to get more out of molecular fingerprints: practical tools for microbial ecology

Community-level molecular techniques are widely used in comparative microbial ecology to assess the diversity of microbial communities and their response to changing environments. These include among others denaturing and temperature gradient gel electrophoresis (DGGE/TGGE), single-strand conformation polymorphism (SSCP), length heterogeneity-PCR (LH-PCR), terminal-restriction fragment length polymorphism (tRFLP) and 16S rRNA gene clone libraries. The amount of data derived from these techniques available in literature is continuously increasing and the lack of a universal way to interpret the raw fingerprint itself makes it difficult to compare between different results. Taking the DGGE technique as an example, we propose a setting-independent theoretical interpretation of the DGGE pattern, based on a straightforward processing on three levels of analysis: (i) the range-weighted richness (Rr) reflecting the carrying capacity of the system, (ii) the dynamics (Dy) reflecting the specific rate of species coming to significance, and (iii) functional organization (Fo), defined through a relation between the structure of a microbial community and its functionality. These Rr, Dy and Fo values, each representing a score to describe a microbial community, can be plotted in a 3D graph. The latter represents a visual ecological interpretation of the initial raw fingerprinting pattern.