Neutral processes
Dotaz
Zobrazit nápovědu
Modeling and simulation in science, engineering and technology
ix, 343 s. ; 24 cm
- MeSH
- časové faktory MeSH
- stochastické procesy MeSH
- teoretické modely MeSH
- věda MeSH
- Publikační typ
- monografie MeSH
- Konspekt
- Statistika
- NLK Obory
- statistika, zdravotnická statistika
Complex cellular machines and processes are commonly believed to be products of selection, and it is typically understood to be the job of evolutionary biologists to show how selective advantage can account for each step in their origin and subsequent growth in complexity. Here, we describe how complex machines might instead evolve in the absence of positive selection through a process of "presuppression," first termed constructive neutral evolution (CNE) more than a decade ago. If an autonomously functioning cellular component acquires mutations that make it dependent for function on another, pre-existing component or process, and if there are multiple ways in which such dependence may arise, then dependence inevitably will arise and reversal to independence is unlikely. Thus, CNE is a unidirectional evolutionary ratchet leading to complexity, if complexity is equated with the number of components or steps necessary to carry out a cellular process. CNE can explain "functions" that seem to make little sense in terms of cellular economy, like RNA editing or splicing, but it may also contribute to the complexity of machines with clear benefit to the cell, like the ribosome, and to organismal complexity overall. We suggest that CNE-based evolutionary scenarios are in these and other cases less forced than the selectionist or adaptationist narratives that are generally told.
- MeSH
- biologická evoluce MeSH
- editace RNA MeSH
- fyziologická adaptace MeSH
- genetický drift MeSH
- lidé MeSH
- modely genetické MeSH
- rostliny anatomie a histologie genetika metabolismus MeSH
- sestřih RNA MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Neutral sphingomyelinase 2 (nSMase2) catalyzes the cleavage of sphingomyelin to phosphorylcholine and ceramide, an essential step in the formation and release of exosomes from cells that is critical for intracellular communication. Chronic increase of brain nSMase2 activity and related exosome release have been implicated in various pathological processes, including the progression of Alzheimer's disease (AD), making nSMase2 a viable therapeutic target. Recently, we identified phenyl (R)-(1-(3-(3,4-dimethoxyphenyl)-2,6-dimethylimidazo[1,2-b]pyridazin-8-yl)pyrrolidin-3-yl)carbamate 1 (PDDC), the first nSMase2 inhibitor that possesses both favorable pharmacodynamics and pharmacokinetic (PK) parameters, including substantial oral bioavailability, brain penetration, and significant inhibition of exosome release from the brain in vivo. Herein we demonstrate the efficacy of 1 (PDDC) in a mouse model of AD and detail extensive structure-activity relationship (SAR) studies with 70 analogues, unveiling several that exert similar or higher activity against nSMase2 with favorable pharmacokinetic properties.
- MeSH
- Alzheimerova nemoc farmakoterapie patologie MeSH
- exozómy metabolismus MeSH
- inhibitory enzymů chemie metabolismus farmakologie terapeutické užití MeSH
- lidé MeSH
- modely nemocí na zvířatech MeSH
- mozek metabolismus MeSH
- myši transgenní MeSH
- myši MeSH
- pyridaziny chemie metabolismus terapeutické užití MeSH
- sfingomyelinfosfodiesterasa antagonisté a inhibitory metabolismus farmakologie MeSH
- tělesná hmotnost účinky léků MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- myši MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Autoři se ve svém textu zamýšlejí nad současnými snahami o harmonizaci práce etických komisí v EU v kontextu pokračující globalizace. Kladou otázku univerzality a široké aplikovatelnosti euroatlantických „univerzálních“ etických principů v reálné praxi i v zemích mimo Evropu a Severní Ameriku. Proces harmonizace, globalizace a standardizace v oblasti etiky klinického výzkumu je nutný, ale není bezproblémový. Na příkladu tří snah o institucionální zakotvení procesu globalizace (Global Forum on Bioethics, International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use, a úsilí harmonizovat práci etických komisí v EU) autoři ukazují, že dichotomizace globálního a lokálního, centralizace a decentralizace apod. není oprávněná. Oblast etického rozhodování v klinickém výzkumu lze harmonizovat, standardizovat, globalizovat, ale význam různých zdánlivě neutrálních konceptů je a bude vždy předmětem lokálních re/interpretací a politických a mocenských sporů a debat.
The paper is a reflection on current attempts to harmonise the work of ethics committees in the EU within the context of ongoing globalisation. The question of the universality of the Euro-Atlantic universal ethical principles and their applicability in everyday practices in countries outside Europe and North America is discussed. The process of harmonisation, globalisation and standardisation in the area of clinical research is necessary but not without its problems. In the discussion of three institutional attempts at the globalisation of research ethics principles (Global Forum on Bioethics, International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use, and harmonisation of ethics committees in the EU) authors argue that dichotomisations of global and local, centralisation and decentralisation are not justified. It is possible to harmonise, standardise and globalise the area of ethical decision making in clinical research; but the meaning of various seemingly neutral concepts will always be open to local reinterpretations and political and power conflicts and debates.
G-protein coupled receptors (GPCRs) exist in an equilibrium of multiple conformational states, including different active states, which depend on the nature of the bound ligand. In consequence, different conformational states can initiate specific signal transduction pathways. The study identified compound 7e, which acts as a potent 5-hydroxytryptamine type 6 receptor (5-HT6R) neutral antagonist at Gs and does not impact neurite growth (process controlled by Cdk5). MD simulations highlighted receptor conformational changes for 7e and inverse agonist PZ-1444. In cell-based assays, neutral antagonists of the 5-HT6R (7e and CPPQ), but not inverse agonists (SB-258585, intepirdine, PZ-1444), displayed glioprotective properties against 6-hydroxydopamine-induced and doxorubicin-induced cytotoxicity. These suggest that targeting the activated conformational state of the 5-HT6R with neutral antagonists implicates the protecting properties of astrocytes. Additionally, 7e prevented scopolamine-induced learning deficits in the novel object recognition test in rats. We propose 7e as a probe for further understanding of the functional outcomes of different states of the 5-HT6R.
- MeSH
- agonisté serotoninových receptorů farmakologie MeSH
- antagonisté serotoninu chemická syntéza farmakologie MeSH
- astrocyty účinky léků MeSH
- imidazoly chemická syntéza farmakologie MeSH
- krysa rodu rattus MeSH
- lidé MeSH
- molekulární konformace MeSH
- neurity účinky léků MeSH
- neuroglie účinky léků MeSH
- neuroprotektivní látky chemická syntéza farmakologie MeSH
- poruchy učení chemicky indukované prevence a kontrola MeSH
- potkani Sprague-Dawley MeSH
- pyridiny chemická syntéza farmakologie MeSH
- receptory serotoninové účinky léků MeSH
- receptory spřažené s G-proteiny účinky léků MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The bimolecular reactivity of molecular dications in the gas phase is reviewed from an experimental point of view. Recent research has demonstrated that in addition to the ubiquitous occurrence of electron transfer in the reactions of gaseous dications with neutral molecules, bond-forming reactions play a much larger role than anticipated before. Thus, quite a number of hydrogen-containing dications show proton transfer to neutral reagents as an abundant or even as the major pathway, and also the nature of the neutral reagent itself is decisive for the amount of proton transfer which takes place. Further, several hydrocarbon dications C(m)H(n)(2+) of medium size (m = 6-14, n = 6-10) undergo bond-forming reactions with unsaturated hydrocarbons such as acetylene or benzene, thereby offering new routes for the formation of larger aromatic compounds under extreme conditions such as interstellar environments. Likewise, recent results on the bimolecular reactivity of multiply charged metal ions have revealed the occurrence of a number of new bond-forming reactions which open promising prospects for further research.
- MeSH
- acetylen chemie MeSH
- benzen chemie MeSH
- cyklotrony přístrojové vybavení MeSH
- financování organizované MeSH
- fotochemie MeSH
- hmotnostní spektrometrie metody přístrojové vybavení MeSH
- kationty chemie MeSH
- kovy chemie MeSH
- plyny chemie MeSH
- protony MeSH
- teplota MeSH
- termodynamika MeSH
- transport elektronů MeSH
- uhlovodíky chemie MeSH
- vodík MeSH
Integrated behavioral paradigms such as nociceptive processing coupled to anti-nociceptive responsiveness include systemically-mediated states of alertness, vigilance, motivation, and avoidance. Within a historical and cultural context, opium and its biologically active compounds, codeine and morphine, have been widely used as frontline anti-nociceptive agents. In eukaryotic cells, opiate alkaloids and opioid peptides were evolutionarily fashioned as regulatory factors in neuroimmune, vascular immune, and systemic immune communication and auto-immunoregulation. The significance of opioidergic regulation of immune function was validated by the identification of novel μ and δ opioid receptors on circulating leukocytes. The novel μ3 opioid receptor subtype has been characterized as an opioid peptide-insensitive and opiate alkaloid-selective G protein-coupled receptor (GPCR) that is functionally linked to the activation of constitutive nitric oxide synthase (cNOS). Opioid peptides stimulate granulocyte and immunocyte activation and chemotaxis via activation of a novel leukocyte δ2 receptor subtype. However, opiate alkaloid μ3 receptor agonists inhibit these same cellular activities. Opiate coupling to cNOS and subsequent production and release of mitochondrial nitric oxide (NO) suggests an evolutionary linkage to similar physiological events in prokaryotic cells. A subpopulation of immunocytes from Mytilus edulis and Leucophaea maderae and human granulocytes respond to low opioid concentrations, mediated by the adherence-promoting role of (D-Ala2-D-Met5)-enkephalinamide (DAMA), which is blocked by naloxone in a dose-dependent manner. Neutral endopeptidase 24.11 (NEP), or enkephalinase (CD10), is present on both human and invertebrate immunocytes. Alkaloids, including morphine, are found in both prokaryotic and eukaryotic cells and may have evolved much later in evolution through horizontal gene transfer. It is possible that opioid-mediated regulatory activities were conserved and elaborated during evolution as the central nervous system (CNS) became immunologically isolated by the blood-brain barrier. Thus, opioid receptor coupling became significant for cognitive and behavioural processes. Although opioid peptides and alkaloids work synergistically to suppress nociception, they mediate different actions in immune surveillance. Increased understanding of the evolutionary development of opioid receptors, nociceptive and anti-nociceptive pathways, and immunomodulation may help in the understanding of the development of tolerance to the clinical use of opiates for pain management. The significance of endogenous morphine's importance to evolution can be ascertained by the number of physiological tissues and systems that can be affected by this chemical messenger mechanism, which transcends pain. An integrated review is presented of opioid and opiate receptors, immunomodulation, and pain associated with inflammation, from an evolutionary perspective.
- MeSH
- biologická evoluce MeSH
- bolest metabolismus MeSH
- chování MeSH
- imunita MeSH
- imunomodulace MeSH
- lidé MeSH
- morfin metabolismus MeSH
- opioidní peptidy metabolismus MeSH
- oxid dusnatý metabolismus MeSH
- receptory opiátové genetika metabolismus MeSH
- zánět metabolismus MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Phenotypic invariance-the outcome of purifying selection-is a hallmark of biological importance. However, invariant phenotypes might be controlled by diverged genetic systems in different species. Here, we explore how an important and invariant phenotype-the development of sexually differentiated individuals-is controlled in over two dozen species in the frog family Pipidae. We uncovered evidence in different species for 1) an ancestral W chromosome that is not found in many females and is found in some males, 2) independent losses and 3) autosomal segregation of this W chromosome, 4) changes in male versus female heterogamy, and 5) substantial variation among species in recombination suppression on sex chromosomes. We further provide evidence of, and evolutionary context for, the origins of at least seven distinct systems for regulating sex determination among three closely related genera. These systems are distinct in their genomic locations, evolutionary origins, and/or male versus female heterogamy. Our findings demonstrate that the developmental control of sexual differentiation changed via loss, sidelining, and empowerment of a mechanistically influential gene, and offer insights into novel factors that impinge on the diverse evolutionary fates of sex chromosomes.
- MeSH
- biologická evoluce MeSH
- fenotyp MeSH
- genetický drift MeSH
- molekulární evoluce MeSH
- Pipidae genetika fyziologie MeSH
- pohlavní chromozomy genetika MeSH
- procesy určující pohlaví MeSH
- rekombinace genetická MeSH
- selekce (genetika) MeSH
- sexuální diferenciace MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
Genetic differentiation between three populations of the pied flycatcher Ficedula hypoleuca (Norway, Czech Republic and Spain, respectively) was investigated at microsatellite loci and mitochondrial DNA (mtDNA) sequences and compared with the pattern of differentiation of male plumage colour. The Czech population lives sympatrically with the closely related collared flycatcher (F. albicollis) whereas the other two are allopatric. Allopatric populations are on average more conspicuously coloured than sympatric ones, a pattern that has been explained by sexual selection for conspicuous colour in allopatry and a character displacement on breeding plumage colour in sympatry that reduces the rate of hybridization with the collared flycatcher. The Czech population was genetically indistinguishable from the Norwegian population at microsatellite loci and mtDNA sequences. Recent isolation and/or gene flow may explain the lack of genetic differentiation. Accordingly, different selection on plumage colour in the two populations is either sufficiently strong so that gene flow has little impact on the pattern of colour variation, or differentiation of plumage colour occurred so recently that the (presumably) neutral, fast evolving markers employed here are unable to reflect the differentiation. Genetically, the Spanish population was significantly differentiated from the other populations, but the divergence was much more pronounced at mtDNA compared to microsatellites. This may reflect increased rate of differentiation by genetic drift at the mitochondrial, compared with the nuclear genome, caused by the smaller effective population size of the former genome. In accordance with this interpretation, a genetic pattern consistent with effects of small population size in the Spanish population (genetic drift and inbreeding) were also apparent at the microsatellites, namely reduced allelic diversity and heterozygous deficiency.
- MeSH
- barva MeSH
- biologická evoluce * MeSH
- fenotyp MeSH
- genotyp MeSH
- mikrosatelitní repetice MeSH
- mitochondriální DNA MeSH
- molekulární sekvence - údaje MeSH
- peří MeSH
- selekce (genetika) MeSH
- zeměpis MeSH
- zpěvní ptáci klasifikace genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- srovnávací studie MeSH
- Geografické názvy
- Česká republika MeSH
- Norsko MeSH
- Španělsko MeSH
Neutral trehalase 1 (Nth1) from Saccharomyces cerevisiae catalyzes disaccharide trehalose hydrolysis and helps yeast to survive adverse conditions, such as heat shock, starvation or oxidative stress. 14-3-3 proteins, master regulators of hundreds of partner proteins, participate in many key cellular processes. Nth1 is activated by phosphorylation followed by 14-3-3 protein (Bmh) binding. The activation mechanism is also potentiated by Ca(2+) binding within the EF-hand-like motif. This review summarizes the current knowledge about trehalases and the molecular and structural basis of Nth1 activation. The crystal structure of fully active Nth1 bound to 14-3-3 protein provided the first high-resolution view of a trehalase from a eukaryotic organism and showed 14-3-3 proteins as structural modulators and allosteric effectors of multi-domain binding partners.
