176 research outputs found
Do Different Neurons Age Differently? Direct Genome-Wide Analysis of Aging in Single Identified Cholinergic Neurons
Aplysia californica is a powerful experimental system to study the entire scope of genomic and epigenomic regulation at the resolution of single functionally characterized neurons and is an emerging model in the neurobiology of aging. First, we have identified and cloned a number of evolutionarily conserved genes that are age-related, including components of apoptosis and chromatin remodeling. Second, we performed gene expression profiling of different identified cholinergic neurons between young and aged animals. Our initial analysis indicates that two cholinergic neurons (R2 and LPl1) revealed highly differential genome-wide changes following aging suggesting that on the molecular scale different neurons indeed age differently. Each of the neurons tested has a unique subset of genes differentially expressed in older animals, and the majority of differently expressed genes (including those related to apoptosis and Alzheimer's disease) are found in aging neurons of one but not another type. The performed analysis allows us to implicate (i) cell specific changes in histones, (ii) DNA methylation and (iii) regional relocation of RNAs as key processes underlying age-related changes in neuronal functions and synaptic plasticity. These mechanisms can fine-tune the dynamics of long-term chromatin remodeling, or control weakening and the loss of synaptic connections in aging. At the same time our genomic tests revealed evolutionarily conserved gene clusters associated with aging (e.g., apoptosis-, telomere- and redox-dependent processes, insulin and estrogen signaling and water channels)
Syncytial nets vs. chemical signaling: emerging properties of alternative integrative systems
Molluscan memory of injury: evolutionary insights into chronic pain and neurological disorders.
Molluscan preparations have yielded seminal discoveries in neuroscience, but the experimental advantages of this group have not, until now, been complemented by adequate molecular or genomic information for comparisons to genetically defined model organisms in other phyla. The recent sequencing of the transcriptome and genome of Aplysia californica, however, will enable extensive comparative studies at the molecular level. Among other benefits, this will bring the power of individually identifiable and manipulable neurons to bear upon questions of cellular function for evolutionarily conserved genes associated with clinically important neural dysfunction. Because of the slower rate of gene evolution in this molluscan lineage, more homologs of genes associated with human disease are present in Aplysia than in leading model organisms from Arthropoda (Drosophila) or Nematoda (Caenorhabditis elegans). Research has hardly begun in molluscs on the cellular functions of gene products that in humans are associated with neurological diseases. On the other hand, much is known about molecular and cellular mechanisms of long-term neuronal plasticity. Persistent nociceptive sensitization of nociceptors in Aplysia displays many functional similarities to alterations in mammalian nociceptors associated with the clinical problem of chronic pain. Moreover, in Aplysia and mammals the same cell signaling pathways trigger persistent enhancement of excitability and synaptic transmission following noxious stimulation, and these highly conserved pathways are also used to induce memory traces in neural circuits of diverse species. This functional and molecular overlap in distantly related lineages and neuronal types supports the proposal that fundamental plasticity mechanisms important for memory, chronic pain, and other lasting alterations evolved from adaptive responses to peripheral injury in the earliest neurons. Molluscan preparations should become increasingly useful for comparative studies across phyla that can provide insight into cellular functions of clinically important genes
Recording cilia activity in ctenophores: effects of nitric oxide and low molecular weight transmitters
Cilia are the major effectors in Ctenophores, but very little is known about their transmitter control and integration. Here, we present a simple protocol to monitor and quantify cilia activity and provide evidence for polysynaptic control of cilia coordination in ctenophores. We also screened the effects of several classical bilaterian neurotransmitters (acetylcholine, dopamine, L-DOPA, serotonin, octopamine, histamine, gamma-aminobutyric acid (GABA), L-aspartate, L-glutamate, glycine), neuropeptide (FMRFamide), and nitric oxide (NO) on cilia beating in Pleurobrachia bachei and Bolinopsis infundibulum. NO and FMRFamide produced noticeable inhibitory effects on cilia activity, whereas other tested transmitters were ineffective. These findings further suggest that ctenophore-specific neuropeptides could be major candidates for signal molecules controlling cilia activity in representatives of this early-branching metazoan lineage
Amino acids integrate behaviors in nerveless placozoans
Placozoans are the simplest known free-living animals without recognized neurons and muscles but a complex behavioral repertoire. However, mechanisms and cellular bases of behavioral coordination are unknown. Here, using Trichoplax adhaerens as a model, we described 0.02–0.002 Hz oscillations in locomotory and feeding patterns as evidence of complex multicellular integration; and showed their dependence on the endogenous secretion of signal molecules. Evolutionary conserved low-molecular-weight transmitters (glutamate, aspartate, glycine, GABA, and ATP) acted as coordinators of distinct locomotory and feeding patterns. Specifically, L-glutamate induced and partially mimicked endogenous feeding cycles, whereas glycine and GABA suppressed feeding. ATP-modified feeding is complex, first causing feeding-like cycles and then suppressing feeding. Trichoplax locomotion was modulated by glycine, GABA, and, surprisingly, by animals’ own mucus trails. Mucus triples locomotory speed compared to clean substrates. Glycine and GABA increased the frequency of turns. The effects of the amino acids are likely mediated by numerous receptors (R), including those from ionotropic GluRs, metabotropic GluRs, and GABA-BR families. Eighty-five of these receptors are encoded in the Trichoplax genome, more than in any other animal sequenced. Phylogenetic reconstructions illuminate massive lineage-specific expansions of amino acid receptors in Placozoa, Cnidaria, and Porifera and parallel evolution of nutritional sensing. Furthermore, we view the integration of feeding behaviors in nerveless animals by amino acids as ancestral exaptations that pave the way for co-options of glutamate, glycine, GABA, and ATP as classical neurotransmitters in eumetazoans
Single Neuron Analysis by Capillary Electrophoresis with Fluorescence Spectroscopy
AbstractA technique to identify and quantitate simultaneously more than 30 compounds in individual neurons is described. The method uses nanoliter volume sampling, capillary electrophoresis separation, and wavelength-resolved native fluorescence detection. Limits of detection (LODs) range from the low attomole to the femtomole range, with 5-hydroxytryptamine (or serotonin [5-HT]) LODs being ∼20 attomoles. Although the cellular sample matrix is chemically complex, the combination of electrophoretic migration time and fluorescence spectral information allows positive identification of aromatic monoamines, aromatic amino acids and peptides containing them, flavins, adenosine- and guanosine-nucleotide analogs, and other fluorescent compounds. Individual identified neurons from Aplysia californica and Pleurobranchaea californica are used to demonstrate the applicability and figures of merit of this technique
Збільшення продуктивності промислового газотурбінного двигуна шляхом регулювання витрати охолоджуючого повітря
The modern gas turbine engine has been used in current power generation industry for almost half a century. They are designed to operate with the best efficiency during normal operating conditions and at specific operating points. However, due to power grid demands, different ambient temperatures, fuel types, relative humidity and driven equipment speed the gas turbine units have to work today on partial load too, which can affect the hot gas path condition and life expectancy. At these off-design conditions, gas turbine’s efficiency and life deterioration rate might significantly deviate from the design specifications. In this paper, a digital twin concept for gas turbine unit off-design performance prediction (AxSTREAM® platform) is used. The description of created digital twin is presented. The validation of proposed gas turbine unit digital twin is carried out by comparison with literature source test data. The GTU performance estimation controlling cooling air at part load modes using digital twin was performed.Сучасний газотурбінний двигун використовується в енергетиці вже майже півстоліття. Вони призначені для роботи з максимальною ефективністю при нормальних робочих умовах і в конкретних робочих точках спільної роботи турбіни і компресора. Проте, через вимоги електромережі, зміни температури навколишнього середовища, типу палива, відносної вологості або частоти обертання приводного пристрою, газотурбінні установки змушені сьогодні працювати при частковому навантаженні, що може вплинути на стан проточної частини турбіни і тривалість її життя. При цих внепроектних умовах ефективність газової турбіни і коефіцієнт зносу можуть значно відрізнятися від проектних специфікацій. У даній статті використовується концепція цифрового двійника об'єкта для прогнозування продуктивності турбоагрегату на позапроектних режимах (платформа AxSTREAM®). Представлено опис створеного цифрового двійника. Валідація запропонованого цифрового двійника газотурбінної установки здійснюється шляхом порівняння з даними випробувань наведеними в джерелах інформації. Була виконана оцінка продуктивності ГТУ, при регулюваннi витрати охолоджуючого повітря на режимах часткового навантаження з використанням цифрового двійника
Intervento alla tavola rotonda "Dove sta andando la critica letteraria?"
Marginalità rispetto alle altre letterature e alle altre forme di comunicazione. È questa, secondo lo studioso, la condizione attuale della letteratura italiana
nel sistema globalizzato. È necessario che l'interprete riscopra la sua triplice funzione - critico, filologo, storico della letteratura - per tentare di penetrare nel testo, anche grazie agli apporti fecondi della critica tematica e ai nuovi approcci interdisciplinari della comparatistica
Comparing thyroid and insect hormone signaling
Transitions between different states of development, physiology, and life history are typically mediated by hormones. In insects, metamorphosis and reproductive maturation are regulated by an interaction between the sesquiterpenoid juvenile hormone (JH) and the steroid 20-hydroxy-ecdysone (20E). In vertebrates and some marine invertebrates, the lipophilic thyroid hormones (THs) affect metamorphosis and other life history transitions. Interestingly, when applied to insects, THs can physiologically mimic many facets of JH action, suggesting that the molecular actions of THs and JH/20E might be similar. Here we discuss functional parallels between TH and JH/20E signaling in insects, with a particular focus on the fruit fly, Drosophila melanogaster, a genetically and physiologically tractable model system. Comparing the effects of THs with the well defined physiological roles of insect hormones such as JH and 20E in Drosophila might provide important insights into hormone function and the evolution of endocrine signaling
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