WorldWideScience

Sample records for chemoreceptors

  1. Peripheral chemoreceptors determine the respiratory sensitivity of central chemoreceptors to CO2 : role of carotid body CO2.

    Science.gov (United States)

    Smith, Curtis A; Blain, Grégory M; Henderson, Kathleen S; Dempsey, Jerome A

    2015-09-15

    We asked if the type of carotid body (CB) chemoreceptor stimulus influenced the ventilatory gain of the central chemoreceptors to CO2 . The effect of CB normoxic hypocapnia, normocapnia and hypercapnia (carotid body PCO2 ≈ 22, 41 and 68 mmHg, respectively) on the ventilatory CO2 sensitivity of central chemoreceptors was studied in seven awake dogs with vascularly-isolated and extracorporeally-perfused CBs. Chemosensitivity with one CB was similar to that in intact dogs. In four CB-denervated dogs, absence of hyper-/hypoventilatory responses to CB perfusion with PCO2 of 19-75 mmHg confirmed separation of the perfused CB circulation from the brain. The group mean central CO2 response slopes were increased 303% for minute ventilation (V̇I)(P ≤ 0.01) and 251% for mean inspiratory flow rate (VT /TI ) (P ≤ 0.05) when the CB was hypercapnic vs. hypocapnic; central CO2 response slopes for tidal volume (VT ), breathing frequency (fb ) and rate of rise of the diaphragm EMG increased in 6 of 7 animals but the group mean changes did not reach statistical significance. Group mean central CO2 response slopes were also increased 237% for V̇I(P ≤ 0.01) and 249% for VT /TI (P ≤ 0.05) when the CB was normocapnic vs. hypocapnic, but no significant differences in any of the central ventilatory response indices were found between CB normocapnia and hypercapnia. These hyperadditive effects of CB hyper-/hypocapnia agree with previous findings using CB hyper-/hypoxia.We propose that hyperaddition is the dominant form of chemoreceptor interaction in quiet wakefulness when the chemosensory control system is intact, response gains physiological, and carotid body chemoreceptors are driven by a wide range of O2 and/or CO2 . PMID:26171601

  2. Signaling and sensory adaptation in Escherichia coli chemoreceptors: 2015 update.

    Science.gov (United States)

    Parkinson, John S; Hazelbauer, Gerald L; Falke, Joseph J

    2015-05-01

    Motile Escherichia coli cells track gradients of attractant and repellent chemicals in their environment with transmembrane chemoreceptor proteins. These receptors operate in cooperative arrays to produce large changes in the activity of a signaling kinase, CheA, in response to small changes in chemoeffector concentration. Recent research has provided a much deeper understanding of the structure and function of core receptor signaling complexes and the architecture of higher-order receptor arrays, which, in turn, has led to new insights into the molecular signaling mechanisms of chemoreceptor networks. Current evidence supports a new view of receptor signaling in which stimulus information travels within receptor molecules through shifts in the dynamic properties of adjoining structural elements rather than through a few discrete conformational states. PMID:25834953

  3. SOLITARY CHEMORECEPTOR CELL SURVIVAL IS INDEPENDENT OF INTACT TRIGEMINAL INNERVATION

    OpenAIRE

    Gulbransen, Brian; Silver, Wayne; Finger, Tom

    2008-01-01

    Nasal solitary chemoreceptor cells (SCCs) are a population of specialized chemosensory epithelial cells presumed to broaden trigeminal chemoreceptivity in mammals (Finger et al., 2003). SCCs are innervated by peptidergic trigeminal nerve fibers (Finger et al., 2003) but it is currently unknown if intact innervation is necessary for SCC development or survival. We tested the dependence of SCCs on innervation by eliminating trigeminal nerve fibers during development with neurogenin-1 knockout m...

  4. Chemicals and chemoreceptors: ecologically relevant signals driving behavior in Drosophila.

    Directory of Open Access Journals (Sweden)

    Ana eDepetris-Chauvin

    2015-04-01

    Full Text Available Insects encounter a vast repertoire of chemicals in their natural environment, which can signal positive stimuli like the presence of a food source, a potential mate, or a suitable oviposition site as well as negative stimuli such as competitors, predators, or toxic substances reflecting danger. The presence of specialized chemoreceptors like taste and olfactory receptors allow animals to detect chemicals at short and long distances and accordingly, trigger proper behaviors towards these stimuli. Since the first description of olfactory and taste receptors in Drosophila fifteen years ago, our knowledge on the identity, properties, and function of specific chemoreceptors has increased exponentially. In the last years, multidisciplinary approaches combining genetic tools with electrophysiological techniques, behavioral recording, evolutionary analysis, and chemical ecology studies are shedding light on our understanding on the ecological relevance of specific chemoreceptors for the survival of Drosophila in their natural environment. In this review we discuss the current knowledge on chemoreceptors of both the olfactory and taste systems of the fruitfly. We focus on the relevance of particular receptors for the detection of ecologically relevant cues such as pheromones, food sources, and toxic compounds, and we comment on the behavioral changes that the detection of these chemicals induce in the fly. In particular, we give an updated outlook of the chemical communication displayed during one of the most important behaviors for fly survival, the courtship behavior. Finally, the ecological relevance of specific chemicals can vary depending on the niche occupied by the individual. In that regard, in this review we also highlight the contrast between adult and larval systems and we propose that these differences could reflect distinctive requirements depending on the change of ecological niche occupied by Drosophila along its life cycle.

  5. Carotid body chemoreceptors, sympathetic neural activation, and cardiometabolic disease

    OpenAIRE

    Iturriaga, Rodrigo; Del Rio, Rodrigo; Idiaquez, Juan; Somers, Virend K.

    2016-01-01

    The carotid body (CB) is the main peripheral chemoreceptor that senses the arterial PO2, PCO2 and pH. In response to hypoxemia, hypercapnia and acidosis, carotid chemosensory discharge elicits reflex respiratory, autonomic and cardiovascular adjustments. The classical construct considers the CB as the main peripheral oxygen sensor, triggering reflex physiological responses to acute hypoxemia and facilitating the ventilatory acclimation to chronic hypoxemia at high altitude. However, a growing...

  6. Chronic Interactions Between Carotid Baroreceptors and Chemoreceptors in Obesity Hypertension.

    Science.gov (United States)

    Lohmeier, Thomas E; Iliescu, Radu; Tudorancea, Ionut; Cazan, Radu; Cates, Adam W; Georgakopoulos, Dimitrios; Irwin, Eric D

    2016-07-01

    Carotid bodies play a critical role in protecting against hypoxemia, and their activation increases sympathetic activity, arterial pressure, and ventilation, responses opposed by acute stimulation of the baroreflex. Although chemoreceptor hypersensitivity is associated with sympathetically mediated hypertension, the mechanisms involved and their significance in the pathogenesis of hypertension remain unclear. We investigated the chronic interactions of these reflexes in dogs with sympathetically mediated, obesity-induced hypertension based on the hypothesis that hypoxemia and tonic activation of carotid chemoreceptors may be associated with obesity. After 5 weeks on a high-fat diet, the animals experienced a 35% to 40% weight gain and increases in arterial pressure from 106±3 to 123±3 mm Hg and respiratory rate from 8±1 to 12±1 breaths/min along with hypoxemia (arterial partial pressure of oxygen=81±3 mm Hg) but eucapnia. During 7 days of carotid baroreflex activation by electric stimulation of the carotid sinus, tachypnea was attenuated, and hypertension was abolished before these variables returned to prestimulation values during a recovery period. After subsequent denervation of the carotid sinus region, respiratory rate decreased transiently in association with further sustained reductions in arterial partial pressure of oxygen (to 65±2 mm Hg) and substantial hypercapnia. Moreover, the severity of hypertension was attenuated from 125±2 to 116±3 mm Hg (45%-50% reduction). These findings suggest that hypoxemia may account for sustained stimulation of peripheral chemoreceptors in obesity and that this activation leads to compensatory increases in ventilation and central sympathetic outflow that contributes to neurogenically mediated hypertension. Furthermore, the excitatory effects of chemoreceptor hyperactivity are abolished by chronic activation of the carotid baroreflex. PMID:27160198

  7. Chemoreceptors and cardiovascular control in acute and chronic systemic hypoxia

    Directory of Open Access Journals (Sweden)

    J.M. Marshall

    1998-07-01

    Full Text Available This review describes the ways in which the primary bradycardia and peripheral vasoconstriction evoked by selective stimulation of peripheral chemoreceptors can be modified by the secondary effects of a chemoreceptor-induced increase in ventilation. The evidence that strong stimulation of peripheral chemoreceptors can evoke the behavioural and cardiovascular components of the alerting or defence response which is characteristically evoked by novel or noxious stimuli is considered. The functional significance of all these influences in systemic hypoxia is then discussed with emphasis on the fact that these reflex changes can be overcome by the local effects of hypoxia: central neural hypoxia depresses ventilation, hypoxia acting on the heart causes bradycardia and local hypoxia of skeletal muscle and brain induces vasodilatation. Further, it is proposed that these local influences can become interdependent, so generating a positive feedback loop that may explain sudden infant death syndrome (SIDS. It is also argued that a major contributor to these local influences is adenosine. The role of adenosine in determining the distribution of O2 in skeletal muscle microcirculation in hypoxia is discussed, together with its possible cellular mechanisms of action. Finally, evidence is presented that in chronic systemic hypoxia, the reflex vasoconstrictor influences of the sympathetic nervous system are reduced and/or the local dilator influences of hypoxia are enhanced. In vitro and in vivo findings suggest this is partly explained by upregulation of nitric oxide (NO synthesis by the vascular endothelium which facilitates vasodilatation induced by adenosine and other NO-dependent dilators and attenuates noradrenaline-evoked vasoconstriction.

  8. Lead toxicity promotes autonomic dysfunction with increased chemoreceptor sensitivity.

    Science.gov (United States)

    Geraldes, Vera; Carvalho, Mafalda; Goncalves-Rosa, Nataniel; Tavares, Cristiano; Laranjo, Sérgio; Rocha, Isabel

    2016-05-01

    Mortality and morbidity by toxic metals is an important issue of occupational health. Lead is an ubiquitous heavy metal in our environment despite having no physiological role in biological systems. Being an homeostatic controller is expected that the autonomic nervous system would show a degree of impairment in lead toxicity. In fact, sympathoexcitation associated to high blood pressure and tachypnea has been described together with baroreflex dysfunction. However, the mechanisms underlying the autonomic dysfunction and the interplay between baro- and chemoreflex are not yet fully clarified. The angiotensinogenic PVN-NTS axis (paraventricular nucleus of the hypothalamus - nucleus tractus solitarius axis) is a particularly important neuronal pathway that could be responsible for the autonomic dysfunction and the cardiorespiratory impairment in lead toxicity. Within the current work, we addressed in vivo, baro- and chemoreceptor reflex behaviour, before and after central angiotensin inhibition, in order to better understand the cardiorespiratory autonomic mechanisms underlying the toxic effects of long-term lead exposure. For that, arterial pressure, heart rate, respiratory rate, sympathetic and parasympathetic activity and baro- and chemoreceptor reflex profiles of anaesthetized young adult rats exposed to lead, from foetal period to adulthood, were evaluated. Results showed increased chemosensitivity together with baroreceptor reflex impairment, sympathetic over-excitation, hypertension and tachypnea. Chemosensitivity and sympathetic overexcitation were reversed towards normality values by NTS treatment with A-779, an angiotensin (1-7) antagonist. No parasympathetic changes were observed before and after A-799 treatment. In conclusion, angiotensin (1-7) at NTS level is involved in the autonomic dysfunction observed in lead toxicity. The increased sensitivity of chemoreceptor reflex expresses the clear impairment of autonomic outflow to the cardiovascular and

  9. Regulation of breathing and autonomic outflows by chemoreceptors.

    Science.gov (United States)

    Guyenet, Patrice G

    2014-10-01

    Lung ventilation fluctuates widely with behavior but arterial PCO2 remains stable. Under normal conditions, the chemoreflexes contribute to PaCO2 stability by producing small corrective cardiorespiratory adjustments mediated by lower brainstem circuits. Carotid body (CB) information reaches the respiratory pattern generator (RPG) via nucleus solitarius (NTS) glutamatergic neurons which also target rostral ventrolateral medulla (RVLM) presympathetic neurons thereby raising sympathetic nerve activity (SNA). Chemoreceptors also regulate presympathetic neurons and cardiovagal preganglionic neurons indirectly via inputs from the RPG. Secondary effects of chemoreceptors on the autonomic outflows result from changes in lung stretch afferent and baroreceptor activity. Central respiratory chemosensitivity is caused by direct effects of acid on neurons and indirect effects of CO2 via astrocytes. Central respiratory chemoreceptors are not definitively identified but the retrotrapezoid nucleus (RTN) is a particularly strong candidate. The absence of RTN likely causes severe central apneas in congenital central hypoventilation syndrome. Like other stressors, intense chemosensory stimuli produce arousal and activate circuits that are wake- or attention-promoting. Such pathways (e.g., locus coeruleus, raphe, and orexin system) modulate the chemoreflexes in a state-dependent manner and their activation by strong chemosensory stimuli intensifies these reflexes. In essential hypertension, obstructive sleep apnea and congestive heart failure, chronically elevated CB afferent activity contributes to raising SNA but breathing is unchanged or becomes periodic (severe CHF). Extreme CNS hypoxia produces a stereotyped cardiorespiratory response (gasping, increased SNA). The effects of these various pathologies on brainstem cardiorespiratory networks are discussed, special consideration being given to the interactions between central and peripheral chemoreflexes. PMID:25428853

  10. Carotid body chemoreceptors, sympathetic neural activation, and cardiometabolic disease.

    Science.gov (United States)

    Iturriaga, Rodrigo; Del Rio, Rodrigo; Idiaquez, Juan; Somers, Virend K

    2016-01-01

    The carotid body (CB) is the main peripheral chemoreceptor that senses the arterial PO2, PCO2 and pH. In response to hypoxemia, hypercapnia and acidosis, carotid chemosensory discharge elicits reflex respiratory, autonomic and cardiovascular adjustments. The classical construct considers the CB as the main peripheral oxygen sensor, triggering reflex physiological responses to acute hypoxemia and facilitating the ventilatory acclimation to chronic hypoxemia at high altitude. However, a growing body of experimental evidence supports the novel concept that an abnormally enhanced CB chemosensory input to the brainstem contributes to overactivation of the sympathetic nervous system, and consequent pathology. Indeed, the CB has been implicated in several diseases associated with increases in central sympathetic outflow. These include hypertension, heart failure, sleep apnea, chronic obstructive pulmonary disease and metabolic syndrome. Indeed, ablation of the CB has been proposed for the treatment of severe and resistant hypertension in humans. In this review, we will analyze and discuss new evidence supporting an important role for the CB chemoreceptor in the progression of autonomic and cardiorespiratory alterations induced by heart failure, obstructive sleep apnea, chronic obstructive pulmonary disease and metabolic syndrome. PMID:26920146

  11. Functional Gustatory Role of Chemoreceptors in Drosophila Wings.

    Science.gov (United States)

    Raad, Hussein; Ferveur, Jean-François; Ledger, Neil; Capovilla, Maria; Robichon, Alain

    2016-05-17

    Neuroanatomical evidence argues for the presence of taste sensilla in Drosophila wings; however, the taste physiology of insect wings remains hypothetical, and a comprehensive link to mechanical functions, such as flight, wing flapping, and grooming, is lacking. Our data show that the sensilla of the Drosophila anterior wing margin respond to both sweet and bitter molecules through an increase in cytosolic Ca(2+) levels. Conversely, genetically modified flies presenting a wing-specific reduction in chemosensory cells show severe defects in both wing taste signaling and the exploratory guidance associated with chemodetection. In Drosophila, the chemodetection machinery includes mechanical grooming, which facilitates the contact between tastants and wing chemoreceptors, and the vibrations of flapping wings that nebulize volatile molecules as carboxylic acids. Together, these data demonstrate that the Drosophila wing chemosensory sensilla are a functional taste organ and that they may have a role in the exploration of ecological niches. PMID:27160896

  12. Fernando De Castro and the discovery of the arterial chemoreceptors

    Directory of Open Access Journals (Sweden)

    Constancio eGonzalez

    2014-05-01

    Full Text Available When De Castro entered the carotid body (CB field, the organ was considered to be a small autonomic ganglion, a gland, a glomus or glomerulus, or a paraganglion. In his 1928 paper, De Castro concluded: In sum, the Glomus caroticum is innervated by centripetal fibers, whose trophic centers are located in the sensory ganglia of the glossopharyngeal, and not by centrifugal [efferent] or secretomotor fibers as is the case for glands; these are precisely the facts which lead to suppose that the Glomus caroticum is a sensory organ. A few pages down, De Castro wrote: The Glomus represents an organ with multiple receptors furnished with specialized receptor cells like those of other sensory organs [taste buds?]…As a plausible hypothesis we propose that the Glomus caroticum represents a sensory organ, at present the only one in its kind, dedicated to capture certain qualitative variations in the composition of blood, a function that, possibly by a reflex mechanism would have an effect on the functional activity of other organs… Therefore, the sensory fiber would not be directly stimulated by blood, but via the intermediation of the epithelial cells of the organ, which, as their structure suggests, possess a secretory function which would participate in the stimulation of the centripetal fibers. In our article we will recreate the experiments that allowed Fernando de Castro to reach this first conclusion. Also, we will scrutinize the natural endowments and the scientific knowledge that drove De Castro to make the triple hypotheses: the CB as chemoreceptor [variations in blood composition], as a secondary sensory receptor which functioning involves a chemical synapse, and as a centre, origin of systemic reflexes. After a brief account of the systemic reflex effects resulting from the CB stimulation, we will complete our article with a general view of the cellular-molecular mechanisms currently thought to be involved in the functioning of this arterial

  13. Repellent response functions of the Trg and Tap chemoreceptors of Escherichia coli.

    OpenAIRE

    Yamamoto, K.; Macnab, R M; Imae, Y

    1990-01-01

    The chemoreceptors responsible for the repellent response of Escherichia coli to phenol were investigated. In the absence of all four known methyl-accepting chemoreceptors (Tar, Tsr, Trg, and Tap), cells showed no response to phenol. However, when Trg, which mediates the attractant response to ribose and galactose, was introduced via a plasmid, the cells acquired a repellent response to phenol. About 1 mM phenol induced a clear repellent response; this response was suppressed by 1 mM ribose. ...

  14. Oxygen-sensing by arterial chemoreceptors: Mechanisms and medical translation.

    Science.gov (United States)

    López-Barneo, José; Ortega-Sáenz, Patricia; González-Rodríguez, Patricia; Fernández-Agüera, M Carmen; Macías, David; Pardal, Ricardo; Gao, Lin

    2016-01-01

    Acute O2 sensing is necessary for the activation of cardiorespiratory reflexes (hyperventilation and sympathetic activation), which permit the survival of individuals under hypoxic environments (e.g. high altitude) or medical conditions presenting with reduced capacity for gas exchange between the lung alveoli and the blood. Changes in blood O2 tension are detected by the arterial chemoreceptors, in particular the carotid body (CB), which act in concert with the adrenal medulla (AM) to facilitate rapid adaptations to hypoxia. The field of arterial chemoreception has undergone a considerable expansion in recent years, with many of the fundamental observations made at the molecular and cellular levels serving to improve our understanding of the pathogenesis of numerous medical disorders, and even to propose advances in the treatment strategies. In this review, after a short historical preface, we describe the current model of chemosensory transduction based on the modulation of membrane K(+) channels by O2 in specialized chemoreceptor cells. Recent progress in elucidating the molecular mechanisms underlying the modulation of ion channels by O2 tension, which involves mitochondrial complex I, is also discussed. The discovery in the last few years of a specific population of neural crest-derived stem cells in the CB explains the reversible growth of this organ, an intriguing and unusual property of this type of neuronal tissue that contributes to acclimatization under chronic hypoxia. The essential homeostatic role of the CB-AM axis is clearly evident in newly generated mouse models that reach adulthood, albeit with CB and AM atrophy. These animals exhibit a marked intolerance to even mild hypoxia. CB inhibition or over-activation can have important medical consequences. Respiratory depression by general anesthetics or by opioid use is a common clinical condition that frequently causes death in susceptible individuals. An exaggerated sympathetic outflow due to over

  15. Analysis of putative chemoreceptor proteins of Campylobacter jejuni

    DEFF Research Database (Denmark)

    Vegge, Christina Skovgaard; Brøndsted, Lone; Bang, Dang D.;

    are found to be colonized by C. jejuni and the bacteria are expected to be attracted to this environment by chemotaxis. In order to explore the role of chemotaxis in C. jejuni colonization and to identify chemoreceptors with matching attractants and/or repellants we have constructed deletion mutants of five...... putative chemoreceptors (tlp1, tlp2, tlp3, docB and docC) in the sequenced strain C. jejuni NCTC11168. The chemotactic capacity of these mutants were investigated by quantifying bacterial accumulation in capillaries filled with attractants or repellants and by measuring migration zones towards or away from...

  16. Role of Dickeya dadantii 3937 chemoreceptors in the entry to Arabidopsis leaves through wounds.

    Science.gov (United States)

    Río-Álvarez, Isabel; Muñoz-Gómez, Cristina; Navas-Vásquez, Mariela; Martínez-García, Pedro M; Antúnez-Lamas, María; Rodríguez-Palenzuela, Pablo; López-Solanilla, Emilia

    2015-09-01

    Chemotaxis enables bacteria to move towards an optimal environment in response to chemical signals. In the case of plant-pathogenic bacteria, chemotaxis allows pathogens to explore the plant surface for potential entry sites with the ultimate aim to prosper inside plant tissues and to cause disease. Chemoreceptors, which constitute the sensory core of the chemotaxis system, are usually transmembrane proteins which change their conformation when sensing chemicals in the periplasm and transduce the signal through a kinase pathway to the flagellar motor. In the particular case of the soft-rot pathogen Dickeya dadantii 3937, jasmonic acid released in a plant wound has been found to be a strong chemoattractant which drives pathogen entry into the plant apoplast. In order to identify candidate chemoreceptors sensing wound-derived plant compounds, we carried out a bioinformatics search of candidate chemoreceptors in the genome of Dickeya dadantii 3937. The study of the chemotactic response to several compounds and the analysis of the entry process to Arabidopsis leaves of 10 selected mutants in chemoreceptors allowed us to determine the implications of at least two of them (ABF-0020167 and ABF-0046680) in the chemotaxis-driven entry process through plant wounds. Our data suggest that ABF-0020167 and ABF-0046680 may be candidate receptors of jasmonic acid and xylose, respectively. PMID:25487519

  17. RNA-Seq Analysis of Human Trigeminal and Dorsal Root Ganglia with a Focus on Chemoreceptors.

    Directory of Open Access Journals (Sweden)

    Caroline Flegel

    Full Text Available The chemosensory capacity of the somatosensory system relies on the appropriate expression of chemoreceptors, which detect chemical stimuli and transduce sensory information into cellular signals. Knowledge of the complete repertoire of the chemoreceptors expressed in human sensory ganglia is lacking. This study employed the next-generation sequencing technique (RNA-Seq to conduct the first expression analysis of human trigeminal ganglia (TG and dorsal root ganglia (DRG. We analyzed the data with a focus on G-protein coupled receptors (GPCRs and ion channels, which are (potentially involved in chemosensation by somatosensory neurons in the human TG and DRG. For years, transient receptor potential (TRP channels have been considered the main group of receptors for chemosensation in the trigeminal system. Interestingly, we could show that sensory ganglia also express a panel of different olfactory receptors (ORs with putative chemosensory function. To characterize OR expression in more detail, we performed microarray, semi-quantitative RT-PCR experiments, and immunohistochemical staining. Additionally, we analyzed the expression data to identify further known or putative classes of chemoreceptors in the human TG and DRG. Our results give an overview of the major classes of chemoreceptors expressed in the human TG and DRG and provide the basis for a broader understanding of the reception of chemical cues.

  18. Influence of neonatally administered capsaicin on baroreceptor and chemoreceptor reflexes in the adult rat.

    OpenAIRE

    Bond, S. M.; Cervero, F; McQueen, D S

    1982-01-01

    1 Baroreceptor and chemoreceptor reflex activity was studied in anaesthetized adult rats which had been treated neonatally with a single injection of capsaicin (50 mg/kg s.c.). 2 Pressor responses to bilateral carotid artery occlusion were significantly lower in capsaicin-treated rats compared with vehicle-treated controls. Pressor responses to intravenously injected noradrenaline were similar in the two groups of rats. 3 Resting respiratory minute volume and tidal volume were lower in anaest...

  19. Identification of a Vibrio cholerae chemoreceptor that senses taurine and amino acids as attractants

    OpenAIRE

    So-ichiro Nishiyama; Yohei Takahashi; Kentaro Yamamoto; Daisuke Suzuki; Yasuaki Itoh; Kazumasa Sumita; Yumiko Uchida; Michio Homma; Katsumi Imada; Ikuro Kawagishi

    2016-01-01

    Vibrio cholerae, the etiological agent of cholera, was found to be attracted by taurine (2-aminoethanesulfonic acid), a major constituent of human bile. Mlp37, the closest homolog of the previously identified amino acid chemoreceptor Mlp24, was found to mediate taxis to taurine as well as L-serine, L-alanine, L-arginine, and other amino acids. Methylation of Mlp37 was enhanced upon the addition of taurine and amino acids. Isothermal titration calorimetry demonstrated that a purified periplasm...

  20. Caste-Specific and Sex-Specific Expression of Chemoreceptor Genes in a Termite.

    Science.gov (United States)

    Mitaka, Yuki; Kobayashi, Kazuya; Mikheyev, Alexander; Tin, Mandy M Y; Watanabe, Yutaka; Matsuura, Kenji

    2016-01-01

    The sophisticated colony organization of eusocial insects is primarily maintained through the utilization of pheromones. The regulation of these complex social interactions requires intricate chemoreception systems. The recent publication of the genome of Zootermopsis nevadensis opened a new avenue to study molecular basis of termite caste systems. Although there has been a growing interest in the termite chemoreception system that regulates their sophisticated caste system, the relationship between division of labor and expression of chemoreceptor genes remains to be explored. Using high-throughput mRNA sequencing (RNA-seq), we found several chemoreceptors that are differentially expressed among castes and between sexes in a subterranean termite Reticulitermes speratus. In total, 53 chemoreception-related genes were annotated, including 22 odorant receptors, 7 gustatory receptors, 12 ionotropic receptors, 9 odorant-binding proteins, and 3 chemosensory proteins. Most of the chemoreception-related genes had caste-related and sex-related expression patterns; in particular, some chemoreception genes showed king-biased or queen-biased expression patterns. Moreover, more than half of the genes showed significant age-dependent differences in their expression in female and/or male reproductives. These results reveal a strong relationship between the evolution of the division of labor and the regulation of chemoreceptor gene expression, thereby demonstrating the chemical communication and underlining chemoreception mechanism in social insects. PMID:26760975

  1. Gill chemoreceptors and cardio-respiratory reflexes in the neotropical teleost pacu, Piaractus mesopotamicus.

    Science.gov (United States)

    Leite, C A C; Florindo, L H; Kalinin, A L; Milsom, W K; Rantin, F T

    2007-09-01

    This study examined the location and distribution of O(2) chemoreceptors involved in cardio-respiratory responses to hypoxia in the neotropical teleost, the pacu (Piaractus mesopotamicus). Intact fish and fish experiencing progressive gill denervation by selective transection of cranial nerves IX and X were exposed to gradual hypoxia and submitted to intrabuccal and intravenous injections of NaCN while their heart rate, ventilation rate and ventilation amplitude were measured. The chemoreceptors producing reflex bradycardia were confined to, but distributed along all gill arches, and were sensitive to O(2) levels in the water and the blood. Ventilatory responses to all stimuli, though modified, continued following gill denervation, however, indicating the presence of internally and externally oriented receptors along all gill arches and either in the pseudobranch or at extra-branchial sites. Chemoreceptors located on the first pair of gill arches and innervated by the glossopharyngeal nerve appeared to attenuate the cardiac and respiratory responses to hypoxia. The data indicate that the location and distribution of cardio-respiratory O(2) receptors are not identical to those in tambaqui (Colossoma macropomum) despite their similar habitats and close phylogenetic lineage, although the differences between the two species could reduce to nothing more than the presence or absence of the pseudobranch. PMID:17680247

  2. Caste-Specific and Sex-Specific Expression of Chemoreceptor Genes in a Termite.

    Directory of Open Access Journals (Sweden)

    Yuki Mitaka

    Full Text Available The sophisticated colony organization of eusocial insects is primarily maintained through the utilization of pheromones. The regulation of these complex social interactions requires intricate chemoreception systems. The recent publication of the genome of Zootermopsis nevadensis opened a new avenue to study molecular basis of termite caste systems. Although there has been a growing interest in the termite chemoreception system that regulates their sophisticated caste system, the relationship between division of labor and expression of chemoreceptor genes remains to be explored. Using high-throughput mRNA sequencing (RNA-seq, we found several chemoreceptors that are differentially expressed among castes and between sexes in a subterranean termite Reticulitermes speratus. In total, 53 chemoreception-related genes were annotated, including 22 odorant receptors, 7 gustatory receptors, 12 ionotropic receptors, 9 odorant-binding proteins, and 3 chemosensory proteins. Most of the chemoreception-related genes had caste-related and sex-related expression patterns; in particular, some chemoreception genes showed king-biased or queen-biased expression patterns. Moreover, more than half of the genes showed significant age-dependent differences in their expression in female and/or male reproductives. These results reveal a strong relationship between the evolution of the division of labor and the regulation of chemoreceptor gene expression, thereby demonstrating the chemical communication and underlining chemoreception mechanism in social insects.

  3. Do the carotid body chemoreceptors mediate cardiovascular and sympathetic adjustments induced by sodium overload in rats?

    Science.gov (United States)

    Pedrino, Gustavo R; Mourão, Aline A; Moreira, Marina C S; da Silva, Elaine F; Lopes, Paulo R; Fajemiroye, James O; Schoorlemmer, Guss H M; Sato, Mônica A; Reis, Ângela A S; Rebelo, Ana C S; Cravo, Sergio L

    2016-05-15

    Acute plasma hypernatremia induces several cardiovascular and sympathetic responses. It is conceivable that these responses contribute to rapid sodium excretion and restoration of normal conditions. Afferent pathways mediating these responses are not entirely understood. The present study analyses the effects of acute carotid chemoreceptor inactivation on cardiovascular and sympathetic responses induced by infusion of hypertonic saline (HS). All experiments were performed on anesthetized male Wistar rats instrumented for recording of arterial blood pressure (ABP), renal blood flow (RBF) and renal sympathetic nerve activity (RSNA). Animals were subjected to sham surgery or carotid chemoreceptor inactivation by bilateral ligation of the carotid body artery (CBA). In sham rats (n=8), intravenous infusion of HS (3 M NaCl, 1.8 ml/kg b.wt.) elicited a transient increase (9±2mmHg) in ABP, and long lasting (30 min) increases in RBF (138±5%) and renal vascular conductance (RVC) (128±5%) with concurrent decrease in RSNA (-19±4%). In rats submitted to CBA ligation (n=8), the pressor response to HS was higher (24±2mmHg; p<0.05). However, RBF and RVC responses to HS infusion were significantly reduced (113±5% and 93±4%, respectively) while RSNA was increased (13±2%). When HS (3M NaCl, 200μl) was administrated into internal carotid artery (ICA), distinct sympathetic and cardiovascular responses were observed. In sham-group, HS infusion (3M NaCl, 200μl) into ICA promoted an increase in ABP (26±8mmHg) and RSNA (29±13%). In CBA rats, ABP (-3±5.6mmHg) remained unaltered despite sympathoinhibition (-37.6±5.4%). These results demonstrate that carotid body chemoreceptors play a role in the development of hemodynamic and sympathetic responses to acute HS infusion. PMID:27060222

  4. Ionic currents in dispersed chemoreceptor cells of the mammalian carotid body

    OpenAIRE

    Ureña, J; J. López López; González, Constancio; López-Barneo, J

    1989-01-01

    Ionic currents of enzymatically dispersed type I and type II cells of the carotid body have been studied using the whole cell variant of the patch-clamp technique. Type II cells only have a tiny, slowly activating outward potassium current. By contrast, in every type I chemoreceptor cell studied we found (a) sodium, (b) calcium, and (c) potassium currents. (a) The sodium current has a fast activation time course and an activation threshold at approximately -40 mV. At all voltages inactivation...

  5. Neural respiratory and circulatory interaction during chemoreceptor stimulation and cooling of ventral medulla in cats.

    Science.gov (United States)

    Millhorn, D E

    1986-01-01

    The effects on respiratory and sympathetic neural activity, measured as integrated phrenic and cervical nerve activities respectively, during changing input from the central chemoreceptors was studied in anaesthetized, paralysed cats whose carotid sinus nerves and vagus nerves had been cut. Central respiratory drive was altered either by graded cold block of the intermediate areas, located bilaterally near the ventral surface of the medulla oblongata, or by step increases in end-tidal PCO2. Cervical nerve activity showed both a tonic (or mean) level of activity and a prominent cyclic discharge that was in phase with phrenic nerve activity. Graded focal cooling of the intermediate areas to 20 degrees C when end-tidal PCO2 was kept constant caused progressive decreases in phrenic activity, the amplitude of the inspiratory related discharge and mean arterial pressure, but only a small decrease in mean cervical nerve activity. Cooling the intermediate areas in the absence of the inspiratory related discharge (i.e. when phrenic activity was below the apnoeic threshold) led to a much smaller decrease in arterial pressure. Step increases of end-tidal PCO2 caused progressive increases of both cervical and phrenic nerve activities. The increase in cervical activity was due primarily, if not wholly, to a progressive increase in the amplitude of the inspiratory related discharge. These findings show that the predominant effect on sympathetic activity during stimulation of the central chemoreceptor and graded cold block of the intermediate areas is a change in the amplitude of the inspiratory related discharge and suggest that the change in arterial pressure that accompanies central chemoreceptor stimulation and graded cold block of the intermediate areas is mediated by the inspiratory related discharge rather than by an increase in the mean level of sympathetic activity. When phrenic activity was lowered to below apnoeic threshold by cooling the intermediate areas, step

  6. Identification of a Vibrio cholerae chemoreceptor that senses taurine and amino acids as attractants

    Science.gov (United States)

    Nishiyama, So-ichiro; Takahashi, Yohei; Yamamoto, Kentaro; Suzuki, Daisuke; Itoh, Yasuaki; Sumita, Kazumasa; Uchida, Yumiko; Homma, Michio; Imada, Katsumi; Kawagishi, Ikuro

    2016-01-01

    Vibrio cholerae, the etiological agent of cholera, was found to be attracted by taurine (2-aminoethanesulfonic acid), a major constituent of human bile. Mlp37, the closest homolog of the previously identified amino acid chemoreceptor Mlp24, was found to mediate taxis to taurine as well as L-serine, L-alanine, L-arginine, and other amino acids. Methylation of Mlp37 was enhanced upon the addition of taurine and amino acids. Isothermal titration calorimetry demonstrated that a purified periplasmic fragment of Mlp37 binds directly to taurine, L-serine, L-alanine and L-arginine. Crystal structures of the periplamic domain of Mlp37 revealed that L-serine and taurine bind to the membrane-distal PAS domain in essentially in the same way. The structural information was supported by characterising the in vivo properties of alanine-substituted mutant forms of Mlp37. The fact that the ligand-binding domain of the L-serine complex had a small opening, which would accommodate a larger R group, accounts for the broad ligand specificity of Mlp37 and allowed us to visualise ligand binding to Mlp37 with fluorescently labelled L-serine. Taken together, we conclude that Mlp37 serves as the major chemoreceptor for taurine and various amino acids. PMID:26878914

  7. Expression of D2 dopamine receptor mRNA in the arterial chemoreceptor afferent pathway.

    Science.gov (United States)

    Czyzyk-Krzeska, M F; Lawson, E E; Millhorn, D E

    1992-11-01

    Dopamine is a major neurotransmitter in the arterial chemoreceptor pathway. In the present study we wished to determine if messenger RNAs for dopamine D1 and D2 receptor are expressed in carotid body (type I cells), in sensory neurons of the petrosal ganglion which innervate the carotid body and in sympathetic neurons of the superior cervical ganglion. We failed to detect D1 receptor mRNA in any of these tissues. However, we found that D2 receptor mRNA was expressed by dopaminergic carotid body type I cells. D2 receptor mRNA was also found in petrosal ganglion neurons that innervated the carotid sinus and carotid body. In addition, a large number of sympathetic postganglionic neurons in the superior cervical ganglion expressed D2 receptor mRNA. PMID:1362730

  8. Arterial chemoreceptor activation reduces the activity of parapyramidal serotonergic neurons in rats.

    Science.gov (United States)

    Takakura, A C; Moreira, T S

    2013-05-01

    The parapyramidal (ppy) region targets primarily the intermediolateral cell column and is probably involved in breathing and thermoregulation. In the present study, we tested whether ppy serotonergic neurons respond to activation of central and peripheral chemoreceptors. Bulbospinal ppy neurons (n=30) were recorded extracellularly along with the phrenic nerve activity in urethane/α-chloralose-anesthetized, paralyzed, intact (n=7) or carotid body denervated (n=6) male Wistar rats. In intact animals, most of the ppy neurons were inhibited by hypoxia (n=14 of 19) (8% O2, 30s) (1.5 ± 0.03 vs. control: 2.4 ± 0.2 Hz) or hypercapnia (n=15 of 19) (10% CO2) (1.7 ± 0.1 vs. control: 2.2 ± 0.2 Hz), although some neurons were insensitive to hypoxia (n=3 of 19) or hypercapnia (n=4 of 19). Very few neurons (n=2 of 19) were activated after hypoxia, but not after hypercapnia. In carotid body denervated rats, all the 5HT-ppy neurons (n=11) were insensitive to hypercapnia (2.1 ± 0.1 vs. control: 2.3 ± 0.09 Hz). Biotinamide-labeled cells that were recovered after histochemistry were located in the ppy region. Most labeled cells (90%) showed strong tryptophan hydroxylase immunocytochemical reactivity, indicating that they were serotonergic. The present data reveal that peripheral chemoreceptors reduce the activity of the serotonergic premotor neurons located in the ppy region. It is plausible that the serotonergic neurons of the ppy region could conceivably regulate breathing automaticity and be involved in autonomic regulation. PMID:23403178

  9. Inter-specific and developmental differences on the array of antennal chemoreceptors in four species of triatominae (Hemiptera: Reduviidae

    Directory of Open Access Journals (Sweden)

    M Gracco

    2000-01-01

    Full Text Available The aim of the work was to investigate the pattern of chemoreceptor sensilla in adults and fifth stage nymphs of Rhodnius prolixus, R. neglectus, Triatoma infestans and T. sordida in order to study differences and similarities between genera and species. Three types of sensilla were analyzed by light microscopy: thin-walled trichoidea, thick-walled trichoidea and basiconica. The number of sensilla of each three types were counted. The length of the antennal segments were also used as a variable for the analysis. The statistical analysis showed that the number of these antennal chemoreceptors had significant differences between species and between adults and nymphs of each species. Discriminant analysis separates incompletely the fifth stage nymphs of the four species and showed similarity between them. Discriminant analysis performed with 12 variables of the antennae, allowed a complete separation of the adults of the four species.

  10. Expression of messenger RNAs for peptides and tyrosine hydroxylase in primary sensory neurons that innervate arterial baroreceptors and chemoreceptors.

    Science.gov (United States)

    Czyzyk-Krzeska, M F; Bayliss, D A; Lawson, E E; Millhorn, D E

    1991-08-01

    Retrograde fiber tracing and in situ hybridization were used to determine expression of mRNAs for preprotachykinin A (ppTA), calcitonin gene related peptide (CGRP), preproenkephalin A (ENK), neuropeptide tyrosine (NPY) and somatostatin (SOM) as well as tyrosine hydroxylase (TH) in the petrosal ganglia primary sensory neurons which innervate carotid sinus baroreceptors and carotid body chemoreceptors. Perfusion of the carotid sinus with the retrogradely transported dye (Fluoro-Gold) labeled primary sensory neurons in petrosal ganglion. Numerous somata in the petrosal ganglion labeled with dye contained mRNAs for all the above peptides, except SOM. Moreover, TH mRNA was found in a substantial number of retrogradely labeled cells in the petrosal ganglion. This study provides information concerning which of the numerous peptides identified in sensory neurons of petrosal ganglion may be involved in modulation of the arterial baroreceptor and chemoreceptor reflexes. PMID:1681484

  11. Chemoreceptor Sensitivity ‘in Women Mountaineering Trainees of Different Altitudes Inducted by Trekking to 4350 m

    OpenAIRE

    G. Bhaumik; S.S Purkayastha; R P Sharma; Sharma, Y K; W. Selvamurthy; Banerjee, P. K.

    2005-01-01

    This study was conducted on women mountaineering trainees to evaluate the hypoxic and hypercapnic ventilatory responses, and the precise nature of changes in the sensitivity of chemoreceptors on induction by trekking to 4350 m. Two groups of women belonging to different ethnic origins and residents of different altitudes, ie, moderate-altitude women (MAWMongolians) and low-altitude women (LAW-Caucasians) were the subjects in this study. Tests of sensitivity to hypoxia and hypercapnia were car...

  12. Reductions in carotid chemoreceptor activity with low-dose dopamine improves baroreflex control of heart rate during hypoxia in humans.

    Science.gov (United States)

    Mozer, Michael T; Holbein, Walter W; Joyner, Michael J; Curry, Timothy B; Limberg, Jacqueline K

    2016-07-01

    The purpose of the present investigation was to examine the contribution of the carotid body chemoreceptors to changes in baroreflex control of heart rate with exposure to hypoxia. We hypothesized spontaneous cardiac baroreflex sensitivity (scBRS) would be reduced with hypoxia and this effect would be blunted when carotid chemoreceptor activity was reduced with low-dose dopamine. Fifteen healthy adults (11 M/4 F) completed two visits randomized to intravenous dopamine or placebo (saline). On each visit, subjects were exposed to 5-min normoxia (~99% SpO2), followed by 5-min hypoxia (~84% SpO2). Blood pressure (intra-arterial catheter) and heart rate (ECG) were measured continuously and scBRS was assessed by spectrum and sequence methodologies. scBRS was reduced with hypoxia (P dopamine (P dopamine (P dopamine did not attenuate the decrease in baroreflex sensitivity to falling pressures (scBRS "down-down"; P > 0.05). Present findings are consistent with a reduction in scBRS with systemic hypoxia. Furthermore, we show this effect is partially mediated by the carotid body chemoreceptors, given the fall in scBRS is attenuated when activity of the chemoreceptors is reduced with low-dose dopamine. However, the improvement in scBRS with dopamine appears to be specific to rising blood pressures. These results may have important implications for impairments in baroreflex function common in disease states of acute and/or chronic hypoxemia, as well as the experimental use of dopamine to assess such changes. PMID:27418545

  13. Axial helix rotation as a mechanism for signal regulation inferred from the crystallographic analysis of the E. coli serine chemoreceptor.

    Science.gov (United States)

    Ferris, Hedda U; Zeth, Kornelius; Hulko, Michael; Dunin-Horkawicz, Stanislaw; Lupas, Andrei N

    2014-06-01

    Bacterial chemotaxis receptors are elongated homodimeric coiled-coil bundles, which transduce signals generated in an N-terminal sensor domain across 15-20nm to a conserved C-terminal signaling subdomain. This signal transduction regulates the activity of associated kinases, altering the behavior of the flagellar motor and hence cell motility. Signaling is in turn modulated by selective methylation and demethylation of specific glutamate and glutamine residues in an adaptation subdomain. We have determined the structure of a chimeric protein, consisting of the HAMP domain from Archaeoglobus fulgidus Af1503 and the methyl-accepting domain of Escherichia coli Tsr. It shows a 21nm coiled coil that alternates between two coiled-coil packing modes: canonical knobs-into-holes and complementary x-da, a variant form related to the canonical one by axial rotation of the helices. Comparison of the obtained structure to the Thermotoga maritima chemoreceptor TM1143 reveals that they adopt different axial rotation states in their adaptation subdomains. This conformational change is presumably induced by the upstream HAMP domain and may modulate the affinity of the chemoreceptor to the methylation-demethylation system. The presented findings extend the cogwheel model for signal transmission to chemoreceptors. PMID:24680785

  14. Clustering requires modified methyl-accepting sites in low-abundance but not high-abundance chemoreceptors of Escherichia coli.

    Science.gov (United States)

    Lybarger, Suzanne R; Nair, Usha; Lilly, Angela A; Hazelbauer, Gerald L; Maddock, Janine R

    2005-05-01

    Chemotaxis signalling complexes of Escherichia coli, composed of chemoreceptors, CheA and CheW, form clusters located predominantly at cell poles. As the only kind of receptor in a cell, high-abundance receptors are polar and clustered whereas low-abundance chemoreceptors are polar but largely unclustered. We found that clustering was a function of the cytoplasmic, carboxyl-terminal domain and that effective clustering was conferred on low-abundance receptors by addition of the approximately 20-residue sequence from the carboxyl terminus of either high-abundance receptor. These sequences are different but share a carboxyl-terminal pentapeptide that enhances adaptational covalent modification and allows a physiological balance between modified and unmodified methyl-accepting sites, implying that receptor modification might influence clustering. Thus we investigated directly effects of modification state on chemoreceptor clustering. As the sole receptor type in a cell, low-abundance receptors were clustered only if modified, but high-abundance receptors were clustered independent of extent of modification. This difference could mean that the two receptor types are fundamentally different or that they are poised at different positions in the same conformational equilibrium. Notably, no receptor perturbation we tested altered a predominant location at cell poles, emphasizing a distinction between determinants of clustering and polar localization. PMID:15853891

  15. Contribution of Individual Chemoreceptors to Sinorhizobium meliloti Chemotaxis Towards Amino Acids of Host and Nonhost Seed Exudates.

    Science.gov (United States)

    Webb, Benjamin A; Helm, Richard F; Scharf, Birgit E

    2016-03-01

    Plant seeds and roots exude a spectrum of molecules into the soil that attract bacteria to the spermosphere and rhizosphere, respectively. The alfalfa symbiont Sinorhizobium meliloti utilizes eight chemoreceptors (McpT to McpZ and IcpA) to mediate chemotaxis. Using a modified hydrogel capillary chemotaxis assay that allows data quantification and larger throughput screening, we defined the role of S. meliloti chemoreceptors in sensing its host, Medicago sativa, and a closely related nonhost, Medicago arabica. S. meliloti wild type and most single-deletion strains displayed comparable chemotaxis responses to host or nonhost seed exudate. However, while the mcpZ mutant responded like wild type to M. sativa exudate, its reaction to M. arabica exudate was reduced by 80%. Even though the amino acid (AA) amounts released by both plant species were similar, synthetic AA mixtures that matched exudate profiles contributed differentially to the S. meliloti wild-type response to M. sativa (23%) and M. arabica (37%) exudates, with McpU identified as the most important chemoreceptor for AA. Our results show that S. meliloti is equally attracted to host and nonhost legumes; however, AA play a greater role in attraction to M. arabica than to M. sativa, with McpZ being specifically important in sensing M. arabica. PMID:26713349

  16. Enzyme-linked acute oxygen sensing in airway and arterial chemoreceptors--invited article.

    Science.gov (United States)

    Kemp, J Paul; Peers, C

    2009-01-01

    Researchers have speculated as to the molecular basis of O(2) sensing for decades. In more recent years, since the discovery of ion channels as identified effectors for O(2) sensing pathways, research has focussed on possible pathways coupling a reduction in hypoxia to altered ion channel activity. The most extensively studied systems are the K(+) channels which are inhibited by hypoxia in chemoreceptor tissues (carotid and neuroepithelial bodies). In this review, we consider the evidence supporting the involvement of well defined enzymes in mediating the regulation of K(+) channels by hypoxia. Specifically, we focus on the roles proposed for three enzyme systems; NADPH oxidase, heme oxygenase and AMP activated protein kinase. These systems differ in that the former two utilise O(2) directly (to form superoxide in the case of NADPH oxidase, and as a co-factor in the degradation of heme to carbon monoxide, bilirubin and ferrous iron in the case of heme oxygenase), but the third responds to shifts in the AMP:ATP ratio, so responds to changes in O(2) levels more indirectly. We consider the evidence in favour of each of these systems, and highlight their differential importance in different systems and species. Whilst the evidence for each playing an important role in different tissues is strong, there is a clear need for further study, and current awareness indicates that no one specific cell type may rely on a single mechanism for O(2) sensing. PMID:19536463

  17. Inhibition of the pontine Kölliker-Fuse nucleus reduces genioglossal activity elicited by stimulation of the retrotrapezoid chemoreceptor neurons.

    Science.gov (United States)

    Silva, Josiane N; Lucena, Elvis V; Silva, Talita M; Damasceno, Rosélia S; Takakura, Ana C; Moreira, Thiago S

    2016-07-22

    The Kölliker-Fuse (KF) region, located in the dorsolateral pons, projects to several brainstem areas involved in respiratory regulation, including the chemoreceptor neurons within the retrotrapezoid nucleus (RTN). Several lines of evidence indicate that the pontine KF region plays an important role in the control of the upper airways for the maintenance of appropriate airflow to and from the lungs. Specifically, we hypothesized that the KF region is involved in mediating the response of the hypoglossal motor activity to central respiratory chemoreflex activation and to stimulation of the chemoreceptor neurons within the RTN region. To test this hypothesis, we combined immunohistochemistry and physiological experiments. We found that in the KF, the majority of biotinylated dextran amine (BDA)-labeled axonal varicosities contained detectable levels of vesicular glutamate transporter-2 (VGLUT2), but few contained glutamic acid decarboxylase-67 (GAD67). The majority of the RTN neurons that were FluorGold (FG)-immunoreactive (i.e., projected to the KF) contained hypercapnia-induced Fos, but did not express tyrosine hydroxylase. In urethane-anesthetized sino-aortic denervated and vagotomized male Wistar rats, hypercapnia (10% CO2) or N-methyl-d-aspartate (NMDA) injection (0.1mM) in the RTN increased diaphragm (DiaEMG) and genioglossus muscle (GGEMG) activities and elicited abdominal (AbdEMG) activity. Bilateral injection of muscimol (GABA-A agonist; 2mM) into the KF region reduced the increase in DiaEMG and GGEMG produced by hypercapnia or NMDA into the RTN. Our data suggest that activation of chemoreceptor neurons in the RTN produces a significant increase in the genioglossus muscle activity and the excitatory pathway is dependent on the neurons located in the dorsolateral pontine KF region. PMID:27126558

  18. Cardiorespiratory responses to hypercarbia in tambaqui Colossoma macropomum: chemoreceptor orientation and specificity.

    Science.gov (United States)

    Gilmour, K M; Milsom, W K; Rantin, F T; Reid, S G; Perry, S F

    2005-03-01

    corresponding pH of the hypercarbic water (pH 6.3, 5.6, 5.3 or 4.9, respectively) generally did not stimulate cardiorespiratory responses. These results are in agreement with the hypothesis that in tambaqui, externally oriented chemoreceptors that are predominantly activated by increases in water P(CO2), rather than by accompanying decreases in water pH, are linked to the initiation of cardiorespiratory responses to hypercarbia. PMID:15767310

  19. Extrabranchial chemoreceptors involved in respiratory reflexes in the neotropical fish Colossoma macropomum (the tambaqui).

    Science.gov (United States)

    Milsom, William K; Reid, Stephen G; Rantin, F Tadeu; Sundin, Lena

    2002-06-01

    In a previous study, complete denervation of the gills in the tambaqui Colossoma macropomum did not eliminate the increase in breathing amplitude seen during exposure of this species to hypoxia. The present study was designed to examine other sites of putative O(2)-sensitive receptors that could be involved in this reflex action. Superfusion of the exposed brain of decerebrate, spinalectomized fish did not reveal the presence of central chemoreceptors responsive to hyperoxic, hypoxic, hypercarbic, acidic or alkaline solutions. Subsequent central transection of cranial nerve IX and X, removing not only all innervation of the gills but also sensory input from the lateral-line, cardiac and visceral branches of the vagus nerve, did not eliminate the increase in breathing amplitude that remained following peripheral gill denervation alone. Administration of exogenous catecholamines (10 and 100 nmol kg(-1) adrenaline) to fish with intact brains and minimal surgical preparation reduced both respiratory frequency and amplitude, suggesting that humoral release of adrenaline also could not be responsible for the increase in breathing amplitude that remained following gill denervation. Denervation of the mandibular branches of cranial nerve V and the opercular and palatine branches of cranial nerve VII in gill-denervated fish (either peripheral gill denervation or central section of cranial nerves IX and X), however, did eliminate the response. Thus, our data suggest that hypoxic and hyperoxic ventilatory responses as well as ventilatory responses to internal and external injections of NaCN in the tambaqui arise from O(2)-sensitive receptors in the orobranchial cavity innervated by cranial nerves V and VII and O(2)-sensitive receptors on the gills innervated by cranial nerves IX and X. Our results also revealed the presence of receptors in the gills that account for all of the increase in ventilation amplitude and part of the increase in ventilation frequency during hyperoxic

  20. The periplasmic sensing domain of Vibrio fischeri chemoreceptor protein A (VfcA): cloning, purification and crystallographic analysis.

    Science.gov (United States)

    Salah Ud-Din, Abu Iftiaf Md; Roujeinikova, Anna

    2016-05-01

    Flagella-mediated motility and chemotaxis towards nutrients are important characteristics of Vibrio fischeri that play a crucial role in the development of its symbiotic relationship with its Hawaiian squid host Euprymna scolopes. The V. fischeri chemoreceptor A (VfcA) mediates chemotaxis toward amino acids. The periplasmic sensory domain of VfcA has been crystallized by the hanging-drop vapour-diffusion method using polyethylene glycol 3350 as a precipitating agent. The crystals belonged to space group P1, with unit-cell parameters a = 39.9, b = 57.0, c = 117.0 Å, α = 88.9, β = 80.5, γ = 89.7°. A complete X-ray diffraction data set has been collected to 1.8 Å resolution using cryocooling conditions and synchrotron radiation. PMID:27139830

  1. Chemotaxis to the Quorum-Sensing Signal AI-2 Requires the Tsr Chemoreceptor and the Periplasmic LsrB AI-2-Binding Protein▿

    OpenAIRE

    Hegde, Manjunath; Englert, Derek L.; Schrock, Shanna; Cohn, William B.; Vogt, Christian; Wood, Thomas K.; Manson, Michael D.; Jayaraman, Arul

    2010-01-01

    AI-2 is an autoinducer made by many bacteria. LsrB binds AI-2 in the periplasm, and Tsr is the l-serine chemoreceptor. We show that AI-2 strongly attracts Escherichia coli. Both LsrB and Tsr are necessary for sensing AI-2, but AI-2 uptake is not, suggesting that LsrB and Tsr interact directly in the periplasm.

  2. Chemoreceptor Sensitivity ‘in Women Mountaineering Trainees of Different Altitudes Inducted by Trekking to 4350 m

    Directory of Open Access Journals (Sweden)

    G. Bhaumik

    2005-10-01

    Full Text Available This study was conducted on women mountaineering trainees to evaluate the hypoxic and hypercapnic ventilatory responses, and the precise nature of changes in the sensitivity of chemoreceptors on induction by trekking to 4350 m. Two groups of women belonging to different ethnic origins and residents of different altitudes, ie, moderate-altitude women (MAWMongolians and low-altitude women (LAW-Caucasians were the subjects in this study. Tests of sensitivity to hypoxia and hypercapnia were carried out initially at 2100 m, then during 4 to7 days of sojourn at 4350 m following induction by trekking, and re-tested on return to 2 100 m. The results indicate that there is a significant difference (P c 0.05 of hypoxic ventilatory response in women of two different ethnic groups: Both hypoxic and hypercapnic ventilatory responses increased significantly (P < 0.05 on induction to high altitude. On descent, hypoxic values reverted back to pre-induction levels, whereas hypercapnic ventilatory response showed relatively higher values (P < 0.05.

  3. Crystallization and crystallographic analysis of the ligand-binding domain of the Pseudomonas putida chemoreceptor McpS in complex with malate and succinate

    International Nuclear Information System (INIS)

    The crystallization of the ligand-binding domain of the methyl-accepting chemotaxis protein chemoreceptor McpS (McpS-LBD) is reported. Methyl-accepting chemotaxis proteins (MCPs) are transmembrane proteins that sense changes in environmental signals, generating a chemotactic response and regulating other cellular processes. MCPs are composed of two main domains: a ligand-binding domain (LBD) and a cytosolic signalling domain (CSD). Here, the crystallization of the LBD of the chemoreceptor McpS (McpS-LBD) is reported. McpS-LBD is responsible for sensing most of the TCA-cycle intermediates in the soil bacterium Pseudomonas putida KT2440. McpS-LBD was expressed, purified and crystallized in complex with two of its natural ligands (malate and succinate). Crystals were obtained by both the counter-diffusion and the hanging-drop vapour-diffusion techniques after pre-incubation of McpS-LBD with the ligands. The crystals were isomorphous and belonged to space group C2, with two molecules per asymmetric unit. Diffraction data were collected at the ESRF synchrotron X-ray source to resolutions of 1.8 and 1.9 Å for the malate and succinate complexes, respectively

  4. The role of branchial and orobranchial O2 chemoreceptors in the control of aquatic surface respiration in the neotropical fish tambaqui (Colossoma macropomum): progressive responses to prolonged hypoxia.

    Science.gov (United States)

    Florindo, Luiz H; Leite, Cléo A C; Kalinin, Ana L; Reid, Stephen G; Milsom, William K; Rantin, F Tadeu

    2006-05-01

    The present study examined the role of branchial and orobranchial O(2) chemoreceptors in the cardiorespiratory responses, aquatic surface respiration (ASR), and the development of inferior lip swelling in tambaqui during prolonged (6 h) exposure to hypoxia. Intact fish (control) and three groups of denervated fish (bilateral denervation of cranial nerves IX+X (to the gills), of cranial nerves V+VII (to the orobranchial cavity) or of cranial nerves V alone), were exposed to severe hypoxia (Pw(O)2=10 mmHg) for 360 min. Respiratory frequency (fr) and heart rate (fh) were recorded simultaneously with ASR. Intact (control) fish increased fr, ventilation amplitude (V(AMP)) and developed hypoxic bradycardia in the first 60 min of hypoxia. The bradycardia, however, abated progressively and had returned to normoxic levels by the last hour of exposure to hypoxia. The changes in respiratory frequency and the hypoxic bradycardia were eliminated by denervation of cranial nerves IX and X but were not affected by denervation of cranial nerves V or V+VII. The V(AMP) was not abolished by the various denervation protocols. The fh in fish with denervation of cranial nerves V or V+VII, however, did not recover to control values as in intact fish. After 360 min of exposure to hypoxia only the intact and IX+X denervated fish performed ASR. Denervation of cranial nerve V abolished the ASR behavior. However, all (control and denervated (IX+X, V and V+VII) fish developed inferior lip swelling. These results indicate that ASR is triggered by O(2) chemoreceptors innervated by cranial nerve V but that other mechanisms, such as a direct effect of hypoxia on the lip tissue, trigger lip swelling. PMID:16621951

  5. Carotid chemoreceptor development in mice

    OpenAIRE

    Shirahata, Machiko; Kostuk, Eric W.; Pichard, Luis E

    2012-01-01

    Mice are the most suitable species for understanding genetic aspects of postnatal developments of the carotid body due to the availability of many inbred strains and knockout mice. Our study has shown that the carotid body grows differentially in different mouse strains, indicating the involvement of genes. However, the small size hampers investigating functional development of the carotid body. Hypoxic and/or hyperoxic ventilatory responses have been investigated in newborn mice, but these r...

  6. Sensitivity to chemical stimuli plays a fundamental role in the food preferences. Examples in the evolutionary scale: 1. Role of the walking leg chemoreceptors in the red swamp crayfish Procambarus Clarkii 2. PROP bitter taste sensitivity and its nutritional implications in Humans

    OpenAIRE

    Melis, Melania

    2014-01-01

    In this thesis, we studied two examples of the sensitivity to chemical stimuli and its role in the food preferences in two models of the evolutionary scale. The red swamp crayfish Procambarus clarkii (Girard, 1852) (Crustacea: Decapoda) is an invasive species of freshwater habitats that has spread worldwide. In crayfish, like in other decapod crustaceans, reception of chemical cues occurs by way of peripheral chemoreceptors grouped within sensory hairs and typically located on the cuticle ...

  7. Functional gustatory role of chemoreceptors in drosophila wings

    OpenAIRE

    Raad, Hussein; Ferveur, Jean-François; Ledger, Neil; Capovilla, Maria

    2016-01-01

    Neuroanatomical evidence argues for the presence of taste sensilla in Drosophila wings; however, the taste physiology of insect wings remains hypothetical, and a comprehensive link to mechanical functions, such as flight, wing flapping, and grooming, is lacking. Our data show that the sensilla of the Drosophila anterior wing margin respond to both sweet and bitter molecules through an increase in cytosolic Ca2+ levels. Conversely, genetically modified flies presenting a wing-specific reductio...

  8. Evolutionary genomics reveals conserved structural determinants of signaling and adaptation in microbial chemoreceptors

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, Roger P [ORNL; Jouline, Igor B [ORNL

    2007-01-01

    As an important model for transmembrane signaling, methyl-accepting chemotaxis proteins (MCPs) have been extensively studied by using genetic, biochemical, and structural techniques. However, details of the molecular mechanism of signaling are still not well understood. The availability of genomic information for hundreds of species enables the identification of features in protein sequences that are conserved over long evolutionary distances and thus are critically important for function. We carried out a large-scale comparative genomic analysis of the MCP signaling and adaptation domain family and identified features that appear to be critical for receptor structure and function. Based on domain length and sequence conservation, we identified seven major MCP classes and three distinct structural regions within the cytoplasmic domain: signaling, methylation, and flexible bundle subdomains. The flexible bundle subdomain, not previously recognized in MCPs, is a conserved element that appears to be important for signal transduction. Remarkably, the N- and C-terminal helical arms of the cytoplasmic domain maintain symmetry in length and register despite dramatic variation, from 24 to 64 7-aa heptads in overall domain length. Loss of symmetry is observed in some MCPs, where it is concomitant with specific changes in the sensory module. Each major MCP class has a distinct pattern of predicted methylation sites that is well supported by experimental data. Our findings indicate that signaling and adaptation functions within the MCP cytoplasmic domain are tightly coupled, and that their coevolution has contributed to the significant diversity in chemotaxis mechanisms among different organisms.

  9. Interindividual variability in the dose-specific effect of dopamine on carotid chemoreceptor sensitivity to hypoxia.

    Science.gov (United States)

    Limberg, Jacqueline K; Johnson, Blair D; Holbein, Walter W; Ranadive, Sushant M; Mozer, Michael T; Joyner, Michael J

    2016-01-15

    Human studies use varying levels of low-dose (1-4 μg·kg(-1)·min(-1)) dopamine to examine peripheral chemosensitivity, based on its known ability to blunt carotid body responsiveness to hypoxia. However, the effect of dopamine on the ventilatory responses to hypoxia is highly variable between individuals. Thus we sought to determine 1) the dose response relationship between dopamine and peripheral chemosensitivity as assessed by the ventilatory response to hypoxia in a cohort of healthy adults, and 2) potential confounding cardiovascular responses at variable low doses of dopamine. Young, healthy adults (n = 30, age = 32 ± 1, 24 male/6 female) were given intravenous (iv) saline and a range of iv dopamine doses (1-4 μg·kg(-1)·min(-1)) prior to and throughout five hypoxic ventilatory response (HVR) tests. Subjects initially received iv saline, and after each HVR the dopamine infusion rate was increased by 1 μg·kg(-1)·min(-1). Tidal volume, respiratory rate, heart rate, blood pressure, and oxygen saturation were continuously measured. Dopamine significantly reduced HVR at all doses (P dopamine infusion (when assessed by dose) reduced HVR in the high group only (P dopamine on HVR in the low group (P > 0.05). Dopamine infusion also resulted in a reduction in blood pressure (3 μg·kg(-1)·min(-1)) and total peripheral resistance (1-4 μg·kg(-1)·min(-1)), driven primarily by subjects with low baseline chemosensitivity. In conclusion, we did not find a single dose of dopamine that elicited a nadir HVR in all subjects. Additionally, potential confounding cardiovascular responses occur with dopamine infusion, which may limit its usage. PMID:26586909

  10. [Role of carotid chemoreceptors in formation of adaptive reactions in animals].

    Science.gov (United States)

    Agadzhanian, N A; Elfimov, A I; Shevchenko, L V

    2003-01-01

    After surgical denervation of sinocarotid reflexogenic zones and bilateral glomectomy in white laboratory rats oxygen consumption, rectal temperature, rate of cardial contractions and thermoregulatory activity of skeletal muscles display authentic increase. Glomectomy results in decreasing calorigecic effect of noradrenaline. Compensatory increase of thermoregulatory activity of sceletal muscles in response to beta-adrenogenic blocade with inderal in post-glomectomic animals is authentically less, than before inactivation of carotid receptors. In animals after carotid glomectomy resistance to acute hypoxia is clearly reduced. True reduction of number of erythrocytes, of hemoglobin concentration, of hematocrite parameter in post glomectic animals was found, which indicates anemisation phenomena. It was found that glomectomy after adaptation of animals in the mountains of Tien Shan at the height of 3200 m during 30 days didn't substantively change resistance to acute hypoxia. Resistance to acute hypoxia of animals living on mountains (susliks, marmots) is higher than of animals living on plains. Glomectomy performed on animals living on mountain resulted in an insignificant decrease in resistance to acute hypoxia. Resistance to acute hypoxia in postglomectic animals was found to be directly linked with absolute amount of hemoglobin concentration and erythrocyte number. In that way denervation of sinocarotid reflexogenic zones and bilateral glomectomy is an adequate method of comparative research of functions regulation mechanism during formation of adaptive responses in animals in dependence of various factors of external environment in norm, as well, as in pathology. PMID:12918264

  11. Central role of carotid body chemoreceptors in disordered breathing and cardiorenal dysfunction in chronic heart failure

    OpenAIRE

    Marcus, Noah J.; Del Rio, Rodrigo; Schultz, Harold D.

    2014-01-01

    Oscillatory breathing (OB) patterns are observed in pre-term infants, patients with cardio-renal impairment, and in otherwise healthy humans exposed to high altitude. Enhanced carotid body (CB) chemoreflex sensitivity is common to all of these populations and is thought to contribute to these abnormal patterns by destabilizing the respiratory control system. OB patterns in chronic heart failure (CHF) patients are associated with greater levels of tonic and chemoreflex-evoked sympathetic nerve...

  12. Characterization of the Vibrio fischeri Fatty Acid Chemoreceptors, VfcB and VfcB2.

    Science.gov (United States)

    Nikolakakis, K; Monfils, K; Moriano-Gutierrez, S; Brennan, C A; Ruby, E G

    2016-01-01

    Bacteria use a wide variety of methyl-accepting chemotaxis proteins (MCPs) to mediate their attraction to or repulsion from different chemical signals in their environment. The bioluminescent marine bacterium Vibrio fischeri is the monospecific symbiont of the Hawaiian bobtail squid, Euprymna scolopes, and encodes a large repertoire of MCPs that are hypothesized to be used during different parts of its complex, multistage lifestyle. Here, we report the initial characterization of two such MCPs from V. fischeri that are responsible for mediating migration toward short- and medium-chain aliphatic (or fatty) acids. These receptors appear to be distributed among only members of the family Vibrionaceae and are likely descended from a receptor that has been lost by the majority of the members of this family. While chemotaxis greatly enhances the efficiency of host colonization by V. fischeri, fatty acids do not appear to be used as a chemical cue during this stage of the symbiosis. This study presents an example of straight-chain fatty acid chemoattraction and contributes to the growing body of characterized MCP-ligand interactions. PMID:26567312

  13. Identification and tissue expression profile of genes from three chemoreceptor families in an urban pest, Periplaneta americana

    Science.gov (United States)

    Chen, Yan; He, Ming; Li, Zhao-Qun; Zhang, Ya-Nan; He, Peng

    2016-01-01

    Periplaneta americana is a notorious urban pest prevalent in human habitats; very little is known about its chemosensory mechanism. Employing the advanced next-generation sequencing technique, in the present study, we conducted transcriptome sequencing and analysis of the antennae of the adult males and females as well as their mouthparts using an Illumina platform. This resulted in the discovery of a huge number of the members of all major known chemosensory receptor families in P. americana, including 96 odorant receptors (ORs), 53 ionotropic receptors (IRs), and 33 gustatory receptors (GRs). Tissue expression profiles showed most of them mainly expressed in antennae and phylogenetic analysis demonstrated the expansion in the clade distinguishing them from other functionally well-known Lepidoptera species. A high percentage of chemosensory receptor genes (ORs in particular) showing female antenna bias in mRNA expression was observed. Our results provide a basis for further investigations on how P. americana coordinates its chemosensory receptor genes in chemical communication with environments, and for development of novel pest management approaches. PMID:27279336

  14. Integration of chemotaxis, transport and catabolism in Pseudomonas putida and identification of the aromatic acid chemoreceptor PcaY.

    Science.gov (United States)

    Luu, Rita A; Kootstra, Joshua D; Nesteryuk, Vasyl; Brunton, Ceanne N; Parales, Juanito V; Ditty, Jayna L; Parales, Rebecca E

    2015-04-01

    Aromatic and hydroaromatic compounds that are metabolized through the β-ketoadipate catabolic pathway serve as chemoattractants for Pseudomonas putida F1. A screen of P. putida F1 mutants, each lacking one of the genes encoding the 18 putative methyl-accepting chemotaxis proteins (MCPs), revealed that pcaY encodes the MCP required for metabolism-independent chemotaxis to vanillate, vanillin, 4-hydroxybenzoate, benzoate, protocatechuate, quinate, shikimate, as well as 10 substituted benzoates that do not serve as growth substrates for P. putida F1. Chemotaxis was induced during growth on aromatic compounds, and an analysis of a pcaY-lacZ fusion revealed that pcaY is expressed in the presence of β-ketoadipate, a common intermediate in the pathway. pcaY expression also required the transcriptional activator PcaR, indicating that pcaY is a member of the pca regulon, which includes three unlinked gene clusters that encode five enzymes required for the conversion of 4-hydroxybenzoate to tricarboxylic acid cycle intermediates as well as the major facilitator superfamily transport protein PcaK. The 4-hydroxybenzoate permease PcaK was shown to modulate the chemotactic response by facilitating the uptake of 4-hydroxybenzoate, which leads to the accumulation of β-ketoadipate, thereby increasing pcaY expression. The results show that chemotaxis, transport and metabolism of aromatic compounds are intimately linked in P. putida. PMID:25582673

  15. Mlp24 (McpX) of Vibrio cholerae Implicated in Pathogenicity Functions as a Chemoreceptor for Multiple Amino Acids

    OpenAIRE

    Nishiyama, So-ichiro; Suzuki, Daisuke; Itoh, Yasuaki; Suzuki, Kazuho; Tajima, Hirotaka; Hyakutake, Akihiro; Homma, Michio; Butler-Wu, Susan M.; Camilli, Andrew; Kawagishi, Ikuro

    2012-01-01

    The chemotaxis of Vibrio cholerae, the causative agent of cholera, has been implicated in pathogenicity. The bacterium has more than 40 genes for methyl-accepting chemotaxis protein (MCP)-like proteins (MLPs). In this study, we found that glycine and at least 18 l-amino acids, including serine, arginine, asparagine, and proline, serve as attractants to the classical biotype strain O395N1. Based on the sequence comparison with Vibrio parahaemolyticus, we speculated that at least 17 MLPs of V. ...

  16. Signal balancing by the CetABC and CetZ chemoreceptors controls energy taxis in Campylobacter jejuni.

    Directory of Open Access Journals (Sweden)

    Mark Reuter

    Full Text Available The coupling of environmental sensing to flagella-mediated directed motility allows bacteria to move to optimum environments for growth and survival, either by sensing external stimuli (chemotaxis or monitoring internal metabolic status (energy taxis. Sensing is mediated by transducer-like proteins (Tlp, either located in the membrane or in the cytoplasm, which commonly influence motility via the CheA-CheY chemotaxis pathway. In this study we have investigated the role of PAS-domain-containing intracellular Tlp-sensors in energy taxis of the food-borne pathogen Campylobacter jejuni, using plate- and tube-based assays utilising the conversion of the redox indicator dyes triphenyl tetrazolium chloride (TTC and resazurin. Inactivation of the genes encoding the Campylobacter Energy Taxis system (CetA (Tlp9 and CetB (Aer2 in C. jejuni strain NCTC 11168 resulted in reduced taxis. Inactivation of the cj1191c gene, encoding the CetB homolog CetC (Aer1, did not affect taxis per se, but the cetC gene complemented a cetB mutant in trans, indicating that CetC can form a functional signal transduction complex with CetA in the absence of CetB. Inactivation of both CetB and CetC resulted in greatly reduced taxis confirming the role of CetC in energy taxis. Inactivation of the cj1110c gene, encoding Tlp8 (CetZ, a cytoplasmic sensor with two PAS-domains, resulted in increased taxis, a phenotype opposite to that of CetAB. Inactivation of the cheA gene resulted in the same overall phenotype as the cetAB mutant in both wild-type and cetZ backgrounds, suggesting that both systems use the CheA system for signal transduction. Absence of both CetAB and CetZ resulted in the cetAB taxis phenotype, suggesting that CetZ is subordinate to CetAB. In conclusion, we present evidence that C. jejuni balances the input from two counteracting PAS-domain-containing sensory systems to position itself for optimal usage of energy resources.

  17. Signal Balancing by the CetABC and CetZ Chemoreceptors Controls Energy Taxis in Campylobacter jejuni

    OpenAIRE

    Mark Reuter; van Vliet, Arnoud H. M.

    2013-01-01

    The coupling of environmental sensing to flagella-mediated directed motility allows bacteria to move to optimum environments for growth and survival, either by sensing external stimuli (chemotaxis) or monitoring internal metabolic status (energy taxis). Sensing is mediated by transducer-like proteins (Tlp), either located in the membrane or in the cytoplasm, which commonly influence motility via the CheA-CheY chemotaxis pathway. In this study we have investigated the role of PAS-domain-contai...

  18. Acute response of peripheral CCr5 chemoreceptor and NK cells in individuals submitted to a single session of low-intensity strength exercise with blood flow restriction.

    Science.gov (United States)

    Dorneles, Gilson Pires; Colato, Alana Schraiber; Galvão, Simone Lunelli; Ramis, Thiago Rozales; Ribeiro, Jerri Luiz; Romão, Pedro Roosevelt; Peres, Alessandra

    2016-07-01

    The purpose of this study was to compare the peripheral expression of natural killers and CCR5 in a session of low-intensity strength training with vascular occlusion and in high-intensity training. Young males were randomized into session groups of a high-intensity strength training (HI) and a session group of low-intensity strength training with vascular occlusion (LI-BFR). The exercise session consisted in knee extension and bicep curl in 80% 1RM (HI) and 30% 1RM (LI-BFR) with equalized volumes. Blood collection was made before, immediately after and 24 h after each training session. Immunophenotyping was carried out through CD195+ (CCR5) e CD3-CD16+CD56+ (NK) in peripheral blood and analysed by flow cytometry and presented in frequency (%). Peripheral frequency of NK cells showed no significant difference in LI-BFR group in time effect, while a gradual reduction of NK cells was identified in HI group in before-24 h postexercise and after-24 h postexercise comparison. However, significant differences have been found in relative change of NK cells immediately after exercise between sessions. In addition, HI and LI-BFR groups showed a significant reduction in the cells expressed CCR5 during 24 h postsession compared to the postsession, but CCR5 also differed when comparing before-24 h after session in the HI group. No differences were observed amongst the groups. LIO induced CCR5 response similar to the HI session, while the NK cells remained in similar frequency during the studied moments in LI-BFR, but not in HI group, suggesting that local hypoxia created by the blood flow restriction was able to prevent a change in the frequency of peripheral cells and a possible immunosuppression. PMID:25643617

  19. Transcriptomics and identification of the chemoreceptor superfamily of the pupal parasitoid of the oriental fruit fly, Spalangia endius Walker (Hymenoptera: Pteromalidae.

    Directory of Open Access Journals (Sweden)

    Yuping Zhang

    Full Text Available BACKGROUND: The oriental fruit fly, Bactrocera dorsalis Hendel, causes serious losses to fruit production and is one of the most economically important pests in many countries, including China, Spalangia endius Walker is a pupal parasitoid of various dipteran hosts, and may be considered a potentially important ectoparasitic pupal parasitoid of B. dorsalis. However, lack of genetic information on this organism is an obstacle to understanding the mechanisms behind its interaction with this host. Analysis of the S. endius transcriptome is essential to extend the resources of genetic information on this species and, to support studies on S. endius on the host B. dorsalis. METHODOLOGY/PRINCIPAL FINDINGS: We performed de novo assembly RNA-seq of S. endius. We obtained nearly 10 Gbp of data using a HiSeq platform, and 36319 high-quality transcripts using Trinity software. A total of 22443 (61.79% unigenes were aligned to homologous sequences in the jewel wasp and honeybee (Apis florae protein set from public databases. A total of 10037 protein domains were identified in 7892 S. endius transcripts using HMMER3 software. We identified expression of six gustatory receptor and 21 odorant receptor genes in the sample, with only one gene having a high expression level in each family. The other genes had a low expression level, including two genes regulated by splicing. This result may be due to the wasps being kept under laboratory conditions. Additionally, a total of 3727 SSR markers were predicted, which could facilitate the identification of polymorphisms and functional genes within wasp populations. CONCLUSION/SIGNIFICANCE: This transcriptome greatly improves our genetic understanding of S. endius and provides a large number of gene sequences for further study.

  20. Phosphate taxis in Pseudomonas aeruginosa.

    OpenAIRE

    Kato, J.; Ito, A.; Nikata, T; Ohtake, H

    1992-01-01

    Pseudomonas aeruginosa was shown to be attracted to phosphate. The chemotactic response was induced by phosphate starvation. The specificity of chemoreceptors for phosphate was high so that no other tested phosphorus compounds elicited a chemotactic response as strong as that elicited by phosphate. Competition experiments showed that the chemoreceptors for phosphate appeared to be different from those for the common amino acids. Mutants constitutive for alkaline phosphatase showed the chemota...

  1. カエル味覚性舌反射に及ぼすアルコール,アミノ酸および苦味物質の刺激効果

    OpenAIRE

    野村, 浩道; 鈴木, 宏和

    1985-01-01

    It has been shown that alcohol, amino acids and bitter substances applied to the tongue elicit a phasic discharge in the glossopharyngeal nerve of the frog. Thus, we examined whether or not alcohols, amino acids and bitter substances elicit a linguo-hyglossal reflex in the frog. The results obtained suggest that hydrophobic amino acids and bitter substances stimulate only the chemoreceptor, but acids and alcohols may stimulate the nociceptive receptor as well as the chemoreceptor.

  2. Exploring the chemotatic attraction of Campylobacter jejuni in chicken colonization

    DEFF Research Database (Denmark)

    Vegge, Christina Skovgaard; Brøndsted, Lone; Ingmer, Hanne

    Campylobacter jejuni is the primary food borne bacterial pathogen in the developed world and the bacteria causes millions of gastroenteritis cases each year. The most important reservoir for C. jejuni is the gut of chickens, which are colonized commensally and efficiently by this organism....... Predominantly the mucus filled crypts of the lower gastrointestinal tract of chickens are found to be colonized by C. jejuni, and the bacteria are expected to be attracted to this particular environment by chemotaxis. From the full genome sequence of C. jejuni NCTC11168 several chemotactic proteins and...... chemoreceptors have been predicted. In order to explore the role of chemotaxis in C. jejuni colonization we have constructed defined deletion mutants in the putative chemoreceptors. These mutants are analyzed for their motile characteristics and their chemotatic capacity in order to investigate the chemoreceptor...

  3. Regulation of caste differentiation in the honey bee (Apis mellifera L.)

    NARCIS (Netherlands)

    Goewie, E.A.

    1978-01-01

    The nutritional environment of honey-bee larvae affects the juvenile hormone (JH) titre of larval haemolymph and tissues. In this investigation the mechanism for the regulation of caste differentiation has been studied.Chemo- and mechanoreceptors are found on larval mouthparts. Chemoreceptors on max

  4. The anti-malarial drug Mefloquine disrupts central autonomic and respiratory control in the working heart brainstem preparation of the rat

    Directory of Open Access Journals (Sweden)

    Lall Varinder K

    2012-12-01

    Full Text Available Abstract Background Mefloquine is an anti-malarial drug that can have neurological side effects. This study examines how mefloquine (MF influences central nervous control of autonomic and respiratory systems using the arterially perfused working heart brainstem preparation (WHBP of the rat. Recordings of nerve activity were made from the thoracic sympathetic chain and phrenic nerve, while heart rate (HR and perfusion pressure were also monitored in the arterially perfused, decerebrate, rat WHBP. MF was added to the perfusate at 1 μM to examine its effects on baseline parameters as well as baroreceptor and chemoreceptor reflexes. Results MF caused a significant, atropine resistant, bradycardia and increased phrenic nerve discharge frequency. Chemoreceptor mediated sympathoexcitation (elicited by addition of 0.1 ml of 0.03% sodium cyanide to the aortic cannula was significantly attenuated by the application of MF to the perfusate. Furthermore MF significantly decreased rate of return to resting HR following chemoreceptor induced bradycardia. An increase in respiratory frequency and attenuated respiratory-related sympathetic nerve discharge during chemoreceptor stimulation was also elicited with MF compared to control. However, MF did not significantly alter baroreceptor reflex sensitivity. Conclusions These studies indicate that in the WHBP, MF causes profound alterations in autonomic and respiratory control. The possibility that these effects may be mediated through actions on connexin 36 containing gap junctions in central neurones controlling sympathetic nervous outflow is discussed.

  5. Using the Pathophysiology of Obstructive Sleep Apnea to Teach Cardiopulmonary Integration

    Science.gov (United States)

    Levitzky, Michael G.

    2008-01-01

    Obstructive sleep apnea (OSA) is a common disorder of upper airway obstruction during sleep. The effects of intermittent upper airway obstruction include alveolar hypoventilation, altered arterial blood gases and acid-base status, and stimulation of the arterial chemoreceptors, which leads to frequent arousals. These arousals disturb sleep…

  6. Immunohistochemical and Morphological Changes in Chipmunk Carotid Body during Hibernaiton

    OpenAIRE

    FUKUHARA, Kohko; YOSHIZAKI, Katsuaki; Wu, Yi; Senoo, Haruki; OHTOMO, Kazuo

    2004-01-01

    Mammalian hibernators experience drastic changes in vital signs such asbody temperature, respiratory rate, and heart rate during hibernation because of periodicarousals during which vital signs return to non-hibernating levels. The carotid body, anarterial chemoreceptor organ regulating respiration, contains several neuroactive substances.However, little is known about changes of neuroactive substances in the carotidbody during hibernation. Immunohistochemical study using antibodies against n...

  7. Role of α2-adrenergic receptors in the carotid body response to hypoxia

    International Nuclear Information System (INIS)

    Clonidine, which acts in part as an α2-adrenergic receptor agonist, depresses ventilation. The authors examined the role of α2-receptors in carotid chemoreceptor activity. The density of α2-receptors was determined in membrane fractions of 18 cat carotid bodies using 125I-iodoclonidine with 0.1 mM epinephrine or 10 μM SKF-86466 defining nonspecific binding. α2-Adrenergic receptor density averaged 0.6±0.1 fmol/carotid body (mean ± SEM) and was comparable to other sympathetic target tissues. The authors then studied the effects of an agonist (guanabenz) and an antagonist (SKF-86466; 6-Cl-N-methyl-2,3,4,5-tetrahydro-1-H3-benzazepine) specific for α2-receptors on baseline and hypoxia-stimulated carotid body discharge, in 10 anesthetized, paralyzed and artificially ventilated cats. Intracarotid infusion of guanabenz for 5 minutes caused a dose-dependent depression of the baseline activity and reduced the chemoreceptor response to hypoxia by 88.0±5.8% of the vehicle-injected controls. Intravenous administration of SKF-86466 reversed the effects of guanabenz on the carotid body activity. in contrast, chemoreceptor depression caused by dopamine was unaffected by SKF-86466. SKF-86466 alone increased baseline discharge and potentiated the chemoreceptor response to hypoxia by 34.0 ± 9.6% of the controls. These results demonstrate that α2-adrenergic receptors are present in the cat carotid body and they exert an inhibitory influence on the chemoreceptor response to hypoxia

  8. ANTIEMETICS: A REVIEW

    OpenAIRE

    Amit Kumar* 1 and Anoop Kumar 2

    2013-01-01

    The act of emesis is controlled by the vomiting centre in the medulla, which integrates afferent input from the vestibular system, the chemoreceptor trigger zone (CTZ), the cortex and the gut. Nausea and vomiting induced by several cancer chemotherapy agents is often the most distressing side effect of treatment. The mechanism of action of antiemetic is related to blockage of various type of receptor located in various region of various organ of the body parts. Various drugs are classified un...

  9. Role of Autonomic Reflex Arcs in Cardiovascular Responses to Air Pollution Exposure

    OpenAIRE

    Perez, Christina M.; Hazari, Mehdi S.; Farraj, Aimen K.

    2015-01-01

    The body responds to environmental stressors by triggering autonomic reflexes in the pulmonary receptors, baroreceptors, and chemoreceptors to maintain homeostasis. Numerous studies have shown that exposure to various gases and airborne particles can alter the functional outcome of these reflexes, particularly with respect to the cardiovascular system. Modulation of autonomic neural input to the heart and vasculature following direct activation of sensory nerves in the respiratory system, eli...

  10. Repellent Taxis in Response to Nickel Ion Requires neither Ni2+ Transport nor the Periplasmic NikA Binding Protein▿

    OpenAIRE

    Englert, Derek L.; Adase, Christopher A.; Jayaraman, Arul; Manson, Michael D.

    2010-01-01

    Ni2+ and Co2+ are sensed as repellents by the Escherichia coli Tar chemoreceptor. The periplasmic Ni2+ binding protein, NikA, has been suggested to sense Ni2+. We show here that neither NikA nor the membrane-bound NikB and NikC proteins of the Ni2+ transport system are required for repellent taxis in response to Ni2+.

  11. Modulation of reflexly evoked vagal bradycardias by central 5-HT1A receptors in anaesthetized rabbits

    OpenAIRE

    Skinner, Matthew R; Ramage, Andrew G; Jordan, David

    2002-01-01

    The role of central 5-HT1A receptors in the control of the bradycardia and changes in central respiratory drive, renal nerve activity and blood pressure evoked by stimulating cardiopulmonary afferents with phenylbiguanide, baroreceptors by electrical stimulation of the aortic nerve and chemoreceptors by injections of sodium cyanide (NaCN) in atenolol-pretreated anaesthetized rabbits were studied.Buspirone (100 μg kg−1; i.c.) potentiated the bradycardia (increase in R-R interval) and the chang...

  12. Do polymorphisms in chemosensory genes matter for human ingestive behavior?

    OpenAIRE

    Hayes, John E.; Feeney, Emma L.; Allen, Alissa L.

    2013-01-01

    In the last decade, basic research in chemoreceptor genetics and neurobiology have revolutionized our understanding of individual differences in chemosensation. From an evolutionary perspective, chemosensory variations appear to have arisen in response to different living environments, generally in the avoidance of toxins and to better detect vital food sources. Today, it is often assumed that these differences may drive variable food preferences and choices, with downstream effects on health...

  13. Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius

    OpenAIRE

    Cardoso, Leonardo Máximo; Colombari, Débora Simões Almeida; Menani, José V; Toney, Glenn M.; Chianca, Deoclécio Alves; Colombari, Eduardo

    2009-01-01

    The nucleus tractus solitarius (NTS), a major hindbrain area involved in cardiovascular regulation, receives primary afferent fibers from peripheral baroreceptors and chemoreceptors. Hydrogen peroxide (H2O2) is a relatively stable and diffusible reactive oxygen species (ROS), which acting centrally, may affect neural mechanisms. In the present study, we investigated effects of H2O2 alone or combined with the glutamatergic antagonist kynurenate into the NTS on mean arterial pressure (MAP) and ...

  14. Pathogenic roles of the carotid body inflammation in sleep apnea

    OpenAIRE

    2014-01-01

    Breathing difficulties in sleep are a hallmark of sleep-disordered breathing commonly observed in patients with sleep disorders. The pathophysiology of sleep apnea is in part due to an augmented activity of the carotid body chemoreflex. Arterial chemoreceptors in the carotid body are sensitive to inflammatory cytokines and immunogenic molecules in the circulation, because cytokine receptors are expressed in the carotid body in experimental animals and human. Intriguingly, proinflammatory cyto...

  15. Ventilatory response to high inspired carbon dioxide concentrations in anesthetized dogs

    OpenAIRE

    Loeppky, Jack A.; Ray Risling

    2011-01-01

    Background: The ventilation (IV ) response to inspired CO2 has been extensively studied, but rarely with concentrations >10%. Aims: These experiments were performed to determine whether I V  would increase correspondingly to higher concentrations and according to conventional chemoreceptor time delays. Materials and Methods: We exposed anesthetized dogs acutely, with and without vagotomy and electrical stimulation of the right vagus, to 20-100% CO2-balance O2.and to 0 and 10% O2-balance N2....

  16. Variation of chemosensory receptor content of Campylobacter jejuni strains and modulation of receptor gene expression under different in vivo and in vitro growth conditions

    OpenAIRE

    Day Christopher J; Hartley-Tassell Lauren E; Shewell Lucy K; King Rebecca M; Tram Greg; Day Serena K; Semchenko Evgeny A; Korolik Victoria

    2012-01-01

    Abstract Background Chemotaxis is crucial for the colonisation/infection of hosts with Campylobacter jejuni. Central to chemotaxis are the group A chemotaxis genes that are responsible for sensing the external environment. The distribution of group A chemoreceptor genes, as found in the C. jejuni sequenced strains, tlp1-4, 7, 10 and 11 were determined in 33 clinical human and avian isolates. Results Group A tlp gene content varied among the strains with genes encoding tlp1 (aspartate receptor...

  17. Plasticity in Glutamatergic NTS Neurotransmission

    OpenAIRE

    Kline, David D.

    2008-01-01

    Changes in the physiological state of an animal or human can result in alterations in the cardiovascular and respiratory system in order to maintain homeostasis. Accordingly, the cardiovascular and respiratory systems are not static but readily adapt under a variety of circumstances. The same can be said for the brainstem circuits that control these systems. The nucleus tractus solitarius (NTS) is the central integration site of baroreceptor and chemoreceptor sensory afferent fibers. This cen...

  18. Autonomic processing of the cardiovascular reflexes in the nucleus tractus solitarii

    OpenAIRE

    Machado B.H.; Mauad H.; Chianca Jr. D.A.; Haibara A.S.; Colombari E.

    1997-01-01

    The nucleus tractus solitarii (NTS) receives afferent projections from the arterial baroreceptors, carotid chemoreceptors and cardiopulmonary receptors and as a function of this information produces autonomic adjustments in order to maintain arterial blood pressure within a narrow range of variation. The activation of each of these cardiovascular afferents produces a specific autonomic response by the excitation of neuronal projections from the NTS to the ventrolateral areas of the medulla (n...

  19. Imprecision of Adaptation in Escherichia coli Chemotaxis

    OpenAIRE

    Silke Neumann; Nikita Vladimirov; Krembel, Anna K.; Wingreen, Ned S.; Victor Sourjik

    2014-01-01

    Adaptability is an essential property of many sensory systems, enabling maintenance of a sensitive response over a range of background stimulus levels. In bacterial chemotaxis, adaptation to the preset level of pathway activity is achieved through an integral feedback mechanism based on activity-dependent methylation of chemoreceptors. It has been argued that this architecture ensures precise and robust adaptation regardless of the ambient ligand concentration, making perfect adaptation a cel...

  20. Formyl peptide receptors are candidate chemosensory receptors in the vomeronasal organ

    OpenAIRE

    Liberles, Stephen D.; Horowitz, Lisa F.; Kuang, Donghui; Contos, James J.; Wilson, Kathleen L.; Siltberg-Liberles, Jessica; Liberles, David A; Buck, Linda B.

    2009-01-01

    The identification of receptors that detect environmental stimuli lays a foundation for exploring the mechanisms and neural circuits underlying sensation. The mouse vomeronasal organ (VNO), which detects pheromones and other semiochemicals, has 2 known families of chemoreceptors, V1Rs and V2Rs. Here, we report a third family of mouse VNO receptors comprising 5 of 7 members of the formyl peptide receptor (FPR) family. Unlike other FPRs, which function in the immune system, these FPRs are selec...

  1. The autonomic nervous system at high altitude

    OpenAIRE

    Hainsworth, Roger; Drinkhill, Mark J.; Rivera-Chira, Maria

    2007-01-01

    The effects of hypobaric hypoxia in visitors depend not only on the actual elevation but also on the rate of ascent. Sympathetic activity increases and there are increases in blood pressure and heart rate. Pulmonary vasoconstriction leads to pulmonary hypertension, particularly during exercise. The sympathetic excitation results from hypoxia, partly through chemoreceptor reflexes and partly through altered baroreceptor function. High pulmonary arterial pressures may also cause reflex systemic...

  2. Hypoxia activates nucleus tractus solitarii neurons projecting to the paraventricular nucleus of the hypothalamus

    OpenAIRE

    King, T. Luise; Heesch, Cheryl M.; Clark, Catharine G.; Kline, David D.; Hasser, Eileen M.

    2012-01-01

    Peripheral chemoreceptor afferent information is sent to the nucleus tractus solitarii (nTS), integrated, and relayed to other brain regions to alter cardiorespiratory function. The nTS projects to the hypothalamic paraventricular nucleus (PVN), but activation and phenotype of these projections during chemoreflex stimulation is unknown. We hypothesized that activation of PVN-projecting nTS neurons occurs primarily at high intensities of hypoxia. We assessed ventilation and cardiovascular para...

  3. Comparison of almitrine bismesylate and medroxyprogesterone acetate on oxygenation during wakefulness and sleep in patients with chronic obstructive lung disease.

    OpenAIRE

    Daskalopoulou, E; Patakas, D.; Tsara, V; Zoglopitis, F; Maniki, E

    1990-01-01

    The effects of almitrine bismesylate and medroxyprogesterone acetate on oxygenation during wakefulness and sleep were compared in six patients with chronic obstructive lung disease and carbon dioxide retention. Patients received 1.5 mg/kg almitrine (a peripheral chemoreceptor stimulant), 100 mg of medroxyprogesterone (a central respiratory stimulant), or matched placebo daily for 15 days in random order in a crossover trial. When subjects were awake almitrine increased the ventilatory respons...

  4. The mysterious multi-modal repellency of DEET

    OpenAIRE

    DeGennaro, Matthew

    2015-01-01

    DEET is the most effective insect repellent available and has been widely used for more than half a century. Here, I review what is known about the olfactory and contact mechanisms of DEET repellency. For mosquitoes, DEET has at least two molecular targets: Odorant Receptors (ORs) mediate the effect of DEET at a distance, while unknown chemoreceptors mediate repellency upon contact. Additionally, the ionotropic receptor Ir40a has recently been identified as a putative DEET chemosensor in Dros...

  5. Morphological changes of carotid bodies in acute respiratory distress syndrome: a morphometric study in humans

    OpenAIRE

    E.N.G. Vinhaes; Dolhnikoff, M; Saldiva, P. H. N.

    2002-01-01

    Carotid bodies are chemoreceptors sensitive to a fall of partial oxygen pressure in blood (hypoxia). The morphological alterations of these organs in patients with chronic obstructive pulmonary disease (COPD) and in people living at high altitude are well known. However, it is not known whether the histological profile of human carotid bodies is changed in acute clinical conditions such as acute respiratory distress syndrome (ARDS). The objective of the present study was to perform a quantita...

  6. Effect of Intermittent Hypercapnia on Respiratory Control in Rat Pups

    OpenAIRE

    Steggerda, Justin A.; Mayer, Catherine A; Martin, Richard J.; Wilson, Christopher G.

    2009-01-01

    Preterm infants are subject to fluctuations in blood gas status associated with immature respiratory control. Intermittent hypoxia during early postnatal life has been shown to increase chemoreceptor sensitivity and destabilize the breathing pattern; however, intermittent hypercapnia remains poorly studied. Therefore, to test the hypothesis that intermittent hypercapnia results in altered respiratory control, we examined the effects of daily exposure to intermittent hypercapnia on the ventila...

  7. Functional Oxygen Sensitivity of Astrocytes

    OpenAIRE

    Angelova, P. R.; Kasymov, V.; I. Christie; Sheikhbahaei, S.; Turovsky, E.; Marina, N.; Korsak, A.; Zwicker, J; Teschemacher, A. G.; Ackland, G. L.; Funk, G. D.; Kasparov, S; Abramov, A.Y.; Gourine, A V

    2015-01-01

    In terrestrial mammals, the oxygen storage capacity of the CNS is limited, and neuronal function is rapidly impaired if oxygen supply is interrupted even for a short period of time. However, oxygen tension monitored by the peripheral (arterial) chemoreceptors is not sensitive to regional CNS differences in partial pressure of oxygen (PO2 ) that reflect variable levels of neuronal activity or local tissue hypoxia, pointing to the necessity of a functional brain oxygen sensor. This experimental...

  8. A Short-Term Fasting in Neonates Induces Breathing Instability and Epigenetic Modification in the Carotid Body

    OpenAIRE

    Shirahata, Machiko; Tang, Wan-yee; Kostuk, Eric W

    2015-01-01

    The respiratory control system is not fully developed in newborn, and data suggest that adequate nutrition is important for the development of the respiratory control system. Infants need to be fed every 2–4 h to maintain appropriate energy levels, but a skip of feeding can occur due to social economical reasons or mild sickness of infants. Here, we asked questions if a short-term fasting (1) alters carotid body (CB) chemoreceptor activity and integrated function of the respiratory control sy...

  9. Control of respiration in fish, amphibians and reptiles

    Directory of Open Access Journals (Sweden)

    E.W. Taylor

    2010-05-01

    Full Text Available Fish and amphibians utilise a suction/force pump to ventilate gills or lungs, with the respiratory muscles innervated by cranial nerves, while reptiles have a thoracic, aspiratory pump innervated by spinal nerves. However, fish can recruit a hypobranchial pump for active jaw occlusion during hypoxia, using feeding muscles innervated by anterior spinal nerves. This same pump is used to ventilate the air-breathing organ in air-breathing fishes. Some reptiles retain a buccal force pump for use during hypoxia or exercise. All vertebrates have respiratory rhythm generators (RRG located in the brainstem. In cyclostomes and possibly jawed fishes, this may comprise elements of the trigeminal nucleus, though in the latter group RRG neurons have been located in the reticular formation. In air-breathing fishes and amphibians, there may be separate RRG for gill and lung ventilation. There is some evidence for multiple RRG in reptiles. Both amphibians and reptiles show episodic breathing patterns that may be centrally generated, though they do respond to changes in oxygen supply. Fish and larval amphibians have chemoreceptors sensitive to oxygen partial pressure located on the gills. Hypoxia induces increased ventilation and a reflex bradycardia and may trigger aquatic surface respiration or air-breathing, though these latter activities also respond to behavioural cues. Adult amphibians and reptiles have peripheral chemoreceptors located on the carotid arteries and central chemoreceptors sensitive to blood carbon dioxide levels. Lung perfusion may be regulated by cardiac shunting and lung ventilation stimulates lung stretch receptors.

  10. Hygienic grooming is induced by contact chemicals in Drosophila melanogaster

    Directory of Open Access Journals (Sweden)

    Aya Yanagawa

    2014-07-01

    Full Text Available In social insects, grooming is considered as a behavioral defense against pathogen and parasite infections since it contributes to remove microbes from their cuticle. However, stimuli which trigger this behavior are not well characterized yet. We examined if activating contact chemoreceptive sensilla could trigger grooming activities in Drosophila melanogaster. We monitored the grooming responses of decapitated flies to compounds known to activate the immune system e.g. dead Escherichia coli (Ec and lipopolysaccharides (LPS, and to tastants such as quinine, sucrose, and salt. LPS, quinine and Ec were quite effective in triggering grooming movements when touching the distal border of the wings and the legs, while sucrose had no effect. Contact chemoreceptors are necessary and sufficient to elicit such responses, as grooming could not be elicited by LPS in poxn mutants deprived of external taste sensilla, and as grooming was elicited by light when a channel rhodopsin receptor was expressed in bitter-sensitive cells expressing Gr33a. Contact chemoreceptors distributed along the distal border of the wings respond to these tastants by an increased spiking activity, in response to quinine, Ec, LPS, sucrose and KCl. These results demonstrate for the first time that bacterial compounds trigger grooming activities in D. melanogaster, and indicate that contact chemoreceptors located on the wings participate to the detection of such chemicals.

  11. Phylogenetic and transcriptomic analysis of chemosensory receptors in a pair of divergent ant species reveals sex-specific signatures of odor coding.

    Directory of Open Access Journals (Sweden)

    Xiaofan Zhou

    Full Text Available Ants are a highly successful family of insects that thrive in a variety of habitats across the world. Perhaps their best-known features are complex social organization and strict division of labor, separating reproduction from the day-to-day maintenance and care of the colony, as well as strict discrimination against foreign individuals. Since these social characteristics in ants are thought to be mediated by semiochemicals, a thorough analysis of these signals, and the receptors that detect them, is critical in revealing mechanisms that lead to stereotypic behaviors. To address these questions, we have defined and characterized the major chemoreceptor families in a pair of behaviorally and evolutionarily distinct ant species, Camponotus floridanus and Harpegnathos saltator. Through comprehensive re-annotation, we show that these ant species harbor some of the largest yet known repertoires of odorant receptors (Ors among insects, as well as a more modest number of gustatory receptors (Grs and variant ionotropic glutamate receptors (Irs. Our phylogenetic analyses further demonstrate remarkably rapid gains and losses of ant Ors, while Grs and Irs have also experienced birth-and-death evolution to different degrees. In addition, comparisons of antennal transcriptomes between sexes identify many chemoreceptors that are differentially expressed between males and females and between species. We have also revealed an agonist for a worker-enriched OR from C. floridanus, representing the first case of a heterologously characterized ant tuning Or. Collectively, our analysis reveals a large number of ant chemoreceptors exhibiting patterns of differential expression and evolution consistent with sex/species-specific functions. These differentially expressed genes are likely associated with sex-based differences, as well as the radically different social lifestyles observed between C. floridanus and H. saltator, and thus are targets for further functional

  12. Glutamatergic transmission in the nucleus tractus solitarii: from server to peripherals in the cardiovascular information superhighway

    Directory of Open Access Journals (Sweden)

    Talman W.T.

    1997-01-01

    Full Text Available Afferent nerves carrying signals from mechanoreceptors in the aortic arch and carotid sinus terminate predominantly in the nucleus tractus solitarii (NTS. Signal transduction and neurotransmission in the NTS are critical for central cardiovascular reflex control, but little was known about either until the late 1970's. None of the numerous neuroactive chemicals found in the NTS had met strict criteria as a neurotransmitter in the baroreflex arc until data suggested that the excitatory amino acid L-glutamate (GLU might be released from baroreceptor afferent terminals in the NTS. In anesthetized animals microinjection into the NTS of GLU, which can be demonstrated in terminals in the NTS, produces cardiovascular responses like those seen with activation of the baroreceptor reflex. Similar responses occur in awake animals if the chemoreceptor reflex is eliminated; otherwise, in conscious animals responses mimic those of chemoreceptor reflex activation. GLU is released in the NTS upon selective activation of the baroreceptor, and possibly the chemoreceptor, reflex. Responses to selective agonists as well as baroreflex responses are eliminated by GLU antagonists microinjected into the NTS. Non-NMDA (N-methyl-D-aspartic acid receptors seem to predominate at primary baroreceptor synapses in the NTS while NMDA receptors may be involved at later synapses. Although inhibition of soluble guanylate cyclase attenuates responses to ionotropic glutamate agonists in the NTS, nitric oxide does not seem to play a role in glutamate transmission in the NTS. GLU may also participate in transmission at cardiovascular neurons beyond the NTS. For example, a role has been suggested for GLU in the ventrolateral medulla and spinal cord. Work continues concerning GLU signal transduction and mechanisms that modulate that transduction both at the NTS and at other cardiovascular nuclei

  13. Changes associated with laboratory rearing in antennal sensilla patterns of Triatoma infestans, Rhodnius prolixus, and Rhodnius pallescens (Hemiptera, Reduviidae, Triatominae

    Directory of Open Access Journals (Sweden)

    Catalá SS

    2004-01-01

    Full Text Available We examined changes in the array of antennal sensilla of three species of Triatominae (Triatoma infestans, Rhodnius prolixus, and R. pallescens following their establishment for different periods in laboratory culture. In each case, the laboratory colonies were compared with conspecific samples taken directly from the field, by quantitative analysis of the sensilla arrays on the three distal segments of the antenna in terms of the densities of three types of chemoreceptors (basiconics and thick and thin walled trichoids and one type of mechanoreceptor (bristles. Sensilla densities were compared by ANOVA or non-parametric tests, and by multivariate discriminant analysis. Strains of the same species reared in different laboratories showed significant differences in their sensilla arrays, especially when compared to field-collected material from the same geographic origin. A Bolivian strain of T. infestans reared in the laboratory for 15 years and fed at monthly intervals, showed greatest differences from its conspecific wild forms, especially in terms of reductions in the number of chemoreceptors. By contrast, an Argentine strain of T. infestans reared for 25 years in the laboratory and fed weekly, showed a relative increase in the density of mechanoreceptors. A Colombian strain of R. prolixus reared for 20 years and fed weekly or fortnightly, showed only modest differences in the sensilla array when compared to its wild populations from the same area. However, a Colombian strain of R. pallescens reared for 12 years and fed fortnightly, did show highly significant reductions in one form of chemoreceptor compared to its conspecific wild populations. For all populations, multivariate analysis clearly discriminated between laboratory and field collected specimens, suggesting that artificial rearing can lead to modifications in the sensory array. This not only supports the idea of morphological plasticity in these species, but also suggests caution in

  14. Towards the sensory nature of the carotid body: Hering, De Castro and Heymans

    Directory of Open Access Journals (Sweden)

    Fernando De Castro

    2009-12-01

    Full Text Available The carotid body or glomus caroticum is a chemosensory organ bilaterally located between the external and internal carotid arteries. Although known by anatomists since the report included by Von Haller and Taube in the mid XVIIIth century, its detailed study started the first quarter of the XXth. The Austro-German physiologist Heinrich E. Hering studied the cardio-respiratory reflexes searched for the anatomical basis of this reflex in the carotid sinus, while the Ghent School leaded by the physio-pharmacologists Jean-François Heymans and his son Corneille focussed in the cardio-aortic reflexogenic region. In 1925, Fernando De Castro, one of the youngest and more brilliant disciples of Santiago Ramón y Cajal at the Laboratorio de Investigaciones Biológicas (Madrid, Spain, profited from some original novelties in histological procedures to study the fine structure and innervation of the carotid body. De Castro unravelled them in a series of scientific papers published between 1926 and 1929, which became the basis to consider the carotid body as a sensory receptor (or chemoreceptor to detect the chemical changes in the composition of the blood. Indeed, this was the first description of arterial chemoreceptors. Impressed by the novelty and implications of the work of De Castro, Corneille Heymans invited the Spanish neurologist to visit Ghent on two occasions (1929 and 1932, where both performed experiences together. Shortly after, Heymans visited De Castro at the Instituto Cajal (Madrid. From 1932-33, Corneille Heymans focused all his attention on the carotid body his physiological demonstration of De Castro’s hypothesis regarding chemoreceptors was awarded with the Nobel Prize in Physiology or Medicine in 1938, just when Spain was immersed in its catastrophic Civil War.

  15. Astrocytes in the Retrotrapezoid Nucleus Sense H+ by Inhibition of a Kir4.1–Kir5.1-Like Current and May Contribute to Chemoreception by a Purinergic Mechanism

    OpenAIRE

    Wenker, Ian C.; Kréneisz, Orsolya; Nishiyama, Akiko; Mulkey, Daniel K.

    2010-01-01

    Central chemoreception is the mechanism by which CO2/pH sensors regulate breathing in response to tissue pH changes. There is compelling evidence that pH-sensitive neurons in the retrotrapezoid nucleus (RTN) are important chemoreceptors. Evidence also indicates that CO2/H+-evoked adenosine 5′-triphosphate (ATP) release in the RTN, from pH-sensitive astrocytes, contributes to chemoreception. However, mechanism(s) by which RTN astrocytes sense pH is unknown and their contribution to chemorecept...

  16. Current ideas on central chemoreception by neurons and glial cells in the retrotrapezoid nucleus

    OpenAIRE

    Mulkey, Daniel K.; Wenker, Ian C.; Kréneisz, Orsolya

    2010-01-01

    Central chemoreception is the mechanism by which CO2/pH-sensitive neurons (i.e., chemoreceptors) regulate breathing in response to changes in tissue pH. A region of the brain stem called the retrotrapezoid nucleus (RTN) is thought to be an important site of chemoreception (23), and recent evidence suggests that RTN chemoreception involves two interrelated mechanisms: H+-mediated activation of pH-sensitive neurons (38) and purinergic signaling (19), possibly from pH-sensitive glial cells. A th...

  17. Experimental study of the role of blocking of 5-HT3 serotonin receptors and D2 dophamin receptors in the mechanism of early radiation vomiting in monkeys

    International Nuclear Information System (INIS)

    Specific activity of Latranum and Dimetphramidum is studied using experimental model of early radiation vomiting on 17 monkeys, mass 6-9 kg inherent on usual ration of vivarium. The experiments with M. fasciculata monkeys exposed to 137Cs γ-radiation with a dose of 6.9 Gy showed that Latranum, a blocker of serotonin 5-HT3 receptors, is a more efficient antimetric than Dimetphramidum, a D2 dophamin lytic. This suggested by fewer animals with emetic reaction of by less severe vomiting in case they have any. The results agree well with a hypothesis that serotonin receptors are dominant in the chemoreceptor trigger zone of monkeys

  18. Principles of agonist recognition in Cys-loop receptors

    DEFF Research Database (Denmark)

    Lynagh, Timothy Peter; Pless, Stephan Alexander

    2014-01-01

    diverse as glycine and serotonin has been subject to intense research over the last three decades. This review outlines the functional diversity and current structural understanding of agonist-binding sites, including those of invertebrate Cys-loop receptors. Together, this provides a framework to......Cys-loop receptors are ligand-gated ion channels that are activated by a structurally diverse array of neurotransmitters, including acetylcholine, serotonin, glycine, and GABA. After the term "chemoreceptor" emerged over 100 years ago, there was some wait until affinity labeling, molecular cloning...

  19. Anaesthetic challenges in carotid body tumour resection: a case report and review of literature

    Directory of Open Access Journals (Sweden)

    Anuradha Malliwal

    2015-12-01

    Full Text Available Carotid body tumour (CBT is an extremely rare, non-chromaffin paraganglioma arising from chemoreceptor cells at the carotid bifurcation. Reported incidence is 1-2 per 100,000. Surgical excision of the tumour, the definitive treatment, poses several anaesthetic challenges and a high incidence of perioperative morbidity and mortality (20-40%. Very few cases have been reported so far. We report the anaesthetic management of a case of CBT excision with a review of recent literature on the same. [Int J Res Med Sci 2015; 3(12.000: 3897-3900

  20. Exploring the chemotactic attraction of Campylobacter jejuni in chicken colonization

    DEFF Research Database (Denmark)

    Vegge, Christina Skovgaard; Brøndsted, Lone; Ingmer, Hanne

    Campylobacter jejuni is the primary food borne bacterial pathogen in the developed world. The most important reservoir for C. jejuni is the gut of chickens, which are colonized commensally and efficiently by this organism. Predominantly the mucus filled crypts of the lower gastrointestinal tract...... are found to be colonized by C. jejuni, and the bacteria are expected to be attracted to this particular environment by chemotaxis. In order to explore the role of chemotaxis in C. jejuni colonization we are construction deletion mutants in the putative chemoreceptors of the sequenced strain NCTC11168...

  1. Testosterone Deficiency and Sleep Apnea.

    Science.gov (United States)

    Burschtin, Omar; Wang, Jing

    2016-05-01

    Obstructive sleep apnea (OSA) is a common condition among middle-aged men and is often associated with reduced testosterone (T) levels. OSA can contribute to fatigue and sexual dysfunction in men. There is suggestion that T supplementation alters ventilatory responses, possibly through effects on central chemoreceptors. Traditionally, it has been recommended that T replacement therapy (TRT) be avoided in the presence of untreated severe sleep apnea. With OSA treatment, however, TRT may not only improve hypogonadism, but may also alleviate erectile/sexual dysfunction. PMID:27132581

  2. Bilateral neck paragangliomas.

    Science.gov (United States)

    Mumoli, N; Cei, M; Pauletti, M; Ferrito, G; Scazzeri, F

    2009-10-01

    Paragangliomas of the head and neck are rare neoplasms presented as cervical mass, generally bilateral, that arise from chemoreceptors located at the carotid bifurcation (carotid body tumors), along the vagus nerve (vagal paragangliomas), and in the jugular fossa and tympanic cavity (jugulotympanic paragangliomas). They are typically asymptomatic at the beginning, highly vascular, slow-growing and compressing the surrounding anatomic structures. Only radical surgery is the curative treatment for paragangliomas. We present a case of a 62- year-old woman with a diagnosis of bilateral neck paragangliomas where surgical removal was judged burdened by excessive risk because of the size of the tumor. PMID:19622673

  3. Contrasted Evolution of the Vomeronasal Receptor Repertoires in Mammals and Squamate Reptiles

    OpenAIRE

    Brykczynska, Urszula; Tzika, Athanasia C.; Rodriguez, Ivan; Milinkovitch, Michel C

    2013-01-01

    The vomeronasal organ (VNO) is an olfactory structure that detects pheromones and environmental cues. It consists of sensory neurons that express evolutionary unrelated groups of transmembrane chemoreceptors. The predominant V1R and V2R receptor repertoires are believed to detect airborne and water-soluble molecules, respectively. It has been suggested that the shift in habitat of early tetrapods from water to land is reflected by an increase in the ratio of V1R/V2R genes. Snakes, which have ...

  4. Effects of afferent input on the breathing pattern continuum in the tambaqui (Colossoma macropomum).

    Science.gov (United States)

    Reid, Stephen G; Sundin, Lena; Florindo, Luis Henrique; Rantin, Francisco Tadeu; Milsom, William K

    2003-06-12

    This study used a decerebrate and artificially-ventilated preparation to examine the roles of various afferent inputs in breathing pattern formation in the tambaqui (Colossoma macropomum). Three general breathing patterns were observed: (1) regular breathing; (2) frequency cycling and (3) episodic breathing. Under normoxic, normocapnic conditions, 50% of control fish exhibited regular continuous breathing and 50% exhibited frequency cycling. Denervation of the gills and oro-branchial cavity promoted frequency cycling. Central denervation of the glossopharyngeal and vagus nerves produced episodic breathing. Regardless of the denervation state, hyperoxia produced either frequency cycling or episodic breathing while hypoxia and hypercarbia shifted the pattern to frequency cycling and continuous breathing. We suggest that these breathing patterns represent a continuum from continuous to episodic breathing with waxing and waning occupying an intermediate stage. The data further suggest that breathing pattern is influenced by both specific afferent input from chemoreceptors and generalised afferent input while chemoreceptors specific for producing changes in breathing pattern may exist in fish. PMID:12809797

  5. Morphological changes induced by thermal treatment and gamma irradiation on the males' hind legs of Spodoptera littoralis (Noctuidae; Lepidoptera

    Directory of Open Access Journals (Sweden)

    Mai S. EL-Degwi

    2015-10-01

    Full Text Available External morphology of males' hind legs of Spodoptera littoralis subjected to thermal treatment (33 °C and 37 °C or/and irradiated with substerilizing doses of gamma radiation (75, 100 and 150 Gy were studied using scanning electron microscopy (SEM in the parental generation. Five types of sensilla have been distinguished; three types of trichoid sensilla (T1,T2 and T3, sensilla basiconica and sensilla auricillica, which are considered as olfactory chemoreceptors. Moreover, sensilla chaetica are contact chemoreceptors, whereas sensilla styloconica are thermo–hygro/gustatory mechanoreceptors. The impact of thermal treatment or/and gamma irradiation reflect a clear morphological change in S. littoralis legs'sensilla, claws, spurs and scales. Otherwise, the degree of deformity was thermal and dose dependent, as it increased with an increase of the degree of temperature and dose of irradiation applied. Substerilizing doses 75 and 100 Gy, either alone or combined with thermal treatment 33 °C, have low undesirable effects on the hind legs with successful mobility or courtship behavior. Consequently, synergistic effect of gamma radiation and thermal stress induced successful application in the integrated pest management program for controlling S. littoralis.

  6. Evolutionary dynamics of olfactory receptor genes in chordates: interaction between environments and genomic contents

    Directory of Open Access Journals (Sweden)

    Niimura Yoshihito

    2009-12-01

    Full Text Available Abstract Olfaction is essential for the survival of animals. Versatile odour molecules in the environment are received by olfactory receptors (ORs, which form the largest multigene family in vertebrates. Identification of the entire repertories of OR genes using bioinformatics methods from the whole-genome sequences of diverse organisms revealed that the numbers of OR genes vary enormously, ranging from ~1,200 in rats and ~400 in humans to ~150 in zebrafish and ~15 in pufferfish. Most species have a considerable fraction of pseudogenes. Extensive phylogenetic analyses have suggested that the numbers of gene gains and losses are extremely large in the OR gene family, which is a striking example of the birth-and-death evolution. It appears that OR gene repertoires change dynamically, depending on each organism's living environment. For example, higher primates equipped with a well-developed vision system have lost a large number of OR genes. Moreover, two groups of OR genes for detecting airborne odorants greatly expanded after the time of terrestrial adaption in the tetrapod lineage, whereas fishes retain diverse repertoires of genes that were present in aquatic ancestral species. The origin of vertebrate OR genes can be traced back to the common ancestor of all chordate species, but insects, nematodes and echinoderms utilise distinctive families of chemoreceptors, suggesting that chemoreceptor genes have evolved many times independently in animal evolution.

  7. The effects of carbon monoxide on respiratory chemoreflexes in humans

    International Nuclear Information System (INIS)

    As protection against low-oxygen and high-carbon-dioxide environments, the respiratory chemoreceptors reflexly increase breathing. Since CO is also frequently present in such environments, it is important to know whether CO affects the respiratory chemoreflexes responsiveness. Although the peripheral chemoreceptors fail to detect hypoxia produced by CO poisoning, whether CO affects the respiratory chemoreflex responsiveness to carbon dioxide is unknown. The responsiveness of 10 healthy male volunteers were assessed before and after inhalation of ∼1200 ppm CO in air using two iso-oxic rebreathing tests; hypoxic, to emphasize the peripheral chemoreflex, and hyperoxic, to emphasize the central chemoreflex. Although mean (SEM) COHb values of 10.2 (0.2)% were achieved, no statistically significant effects of CO were observed. The average differences between pre- and post-CO values for ventilation response threshold and sensitivity were -0.5 (0.9) mmHg and 0.8 (0.3) L/min/mmHg, respectively, for hyperoxia, and 0.7 (1.1) mmHg and 1.2 (0.8) L/min/mmHg, respectively, for hypoxia. The 95% confidence intervals for the effect of CO were small. We conclude that environments with low levels of CO do not have a clinically significant effect acutely on either the central or the peripheral chemoreflex responsiveness to carbon dioxide

  8. Alleged silk spigots on tarantula feet: electron microscopy reveals sensory innervation, no silk.

    Science.gov (United States)

    Foelix, Rainer; Erb, Bruno; Rast, Bastian

    2013-05-01

    Several studies on tarantulas have claimed that their tarsi could secrete fine silk threads which would provide additional safety lines for maintaining a secure foot-hold on smooth vertical surfaces. This interpretation was seriously questioned by behavioral experiments, and more recently morphological evidence indicated that the alleged spigots ("ribbed hairs") were not secretory but most likely sensory hairs (chemoreceptors). However, since fine structural studies were lacking, the sensory nature was not proven convincingly. By using transmission electron microscopy we here present clear evidence that these "ribbed hairs" contain many dendrites inside the hair lumen - as is the case in the well-known contact chemoreceptors of spiders and insects. For comparison, we also studied the fine structure of regular silk spigots on the spinnerets and found them distinctly different from sensory hairs. Finally, histological studies of a tarantula tarsus did not reveal any silk glands, which, by contrast, are easily found within the spinnerets. In conclusion, the alleged presence of silk spigots on tarantula feet is refuted. PMID:23474440

  9. Hypoxia inhibits abdominal expiratory nerve activity.

    Science.gov (United States)

    Fregosi, R F; Knuth, S L; Ward, D K; Bartlett, D

    1987-07-01

    Our purpose was to examine the influence of steady-state changes in chemical stimuli, as well as discrete peripheral chemoreceptor stimulation, on abdominal expiratory motor activity. In decerebrate, paralyzed, vagotomized, and ventilated cats that had bilateral pneumothoraces, we recorded efferent activity from a phrenic nerve and from an abdominal nerve (cranial iliohypogastric nerve, L1). All cats showed phasic expiratory abdominal nerve discharge at normocapnia [end-tidal PCO2 38 +/- 2 Torr], but small doses (2-6 mg/kg) of pentobarbital sodium markedly depressed this activity. Hyperoxic hypercapnia consistently enhanced abdominal expiratory activity and shortened the burst duration. Isocapnic hypoxia caused inhibition of abdominal nerve discharge in 11 of 13 cats. Carotid sinus nerve denervation (3 cats) exacerbated the hypoxic depression of abdominal nerve activity and depressed phrenic motor output. Stimulation of peripheral chemoreceptors with NaCN increased abdominal nerve discharge in 7 of 10 cats, although 2 cats exhibited marked inhibition. Four cats with intact neuraxis, but anesthetized with ketamine, yielded qualitatively similar results. We conclude that when cats are subjected to steady-state chemical stimuli in isolation (no interference from proprioceptive inputs), hypercapnia potentiates, but hypoxia attenuates, abdominal expiratory nerve activity. Mechanisms to explain the selective inhibition of expiratory motor activity by hypoxia are proposed, and physiological implications are discussed. PMID:3624126

  10. Chemotaxis signaling systems in model beneficial plant-bacteria associations.

    Science.gov (United States)

    Scharf, Birgit E; Hynes, Michael F; Alexandre, Gladys M

    2016-04-01

    Beneficial plant-microbe associations play critical roles in plant health. Bacterial chemotaxis provides a competitive advantage to motile flagellated bacteria in colonization of plant root surfaces, which is a prerequisite for the establishment of beneficial associations. Chemotaxis signaling enables motile soil bacteria to sense and respond to gradients of chemical compounds released by plant roots. This process allows bacteria to actively swim towards plant roots and is thus critical for competitive root surface colonization. The complete genome sequences of several plant-associated bacterial species indicate the presence of multiple chemotaxis systems and a large number of chemoreceptors. Further, most soil bacteria are motile and capable of chemotaxis, and chemotaxis-encoding genes are enriched in the bacteria found in the rhizosphere compared to the bulk soil. This review compares the architecture and diversity of chemotaxis signaling systems in model beneficial plant-associated bacteria and discusses their relevance to the rhizosphere lifestyle. While it is unclear how controlling chemotaxis via multiple parallel chemotaxis systems provides a competitive advantage to certain bacterial species, the presence of a larger number of chemoreceptors is likely to contribute to the ability of motile bacteria to survive in the soil and to compete for root surface colonization. PMID:26797793

  11. Effect of intermittent hypercapnia on respiratory control in rat pups.

    Science.gov (United States)

    Steggerda, Justin A; Mayer, Catherine A; Martin, Richard J; Wilson, Christopher G

    2010-01-01

    Preterm infants are subject to fluctuations in blood gas status associated with immature respiratory control. Intermittent hypoxia during early postnatal life has been shown to increase chemoreceptor sensitivity and destabilize the breathing pattern; however, intermittent hypercapnia remains poorly studied. Therefore, to test the hypothesis that intermittent hypercapnia results in altered respiratory control, we examined the effects of daily exposure to intermittent hypercapnia on the ventilatory response to subsequent hypercapnic and hypoxic exposure in neonatal rat pups. Exposure cycles consisted of 5 min of intermittent hypercapnia (5% CO(2), 21% O(2), balance N(2)) followed by 10 min of normoxia. Rat pups were exposed to 18 exposure cycles each day for 1 week, from postnatal day 7 to 14. We analyzed diaphragm electromyograms (EMGs) from pups exposed to subsequent acute hypercapnic (5% CO(2)) and hypoxic (12% O(2)) challenges. In response to a subsequent hypercapnia challenge, there was no significant difference in the ventilatory response between control and intermittent hypercapnia-exposed groups. In contrast, intermittent hypercapnia-exposed rat pups showed an enhanced ventilatory response to hypoxic challenge with an increase in minute EMG to 118 +/- 14% of baseline versus 107 +/- 13% for control pups (p < 0.05). We speculate that prior hypercapnic exposure may increase peripheral chemoreceptor response to subsequent hypoxic exposures and result in perturbed neonatal respiratory control. PMID:19752577

  12. 颈动脉体的生理和病理功能%Carotid body function in health and disease

    Institute of Scientific and Technical Information of China (English)

    冯文龙

    2012-01-01

    外周颈动脉体化学感受器在介导低动脉血氧、高碳酸血症和酸中毒等信号过程中发挥着重要作用.它将信号传到中枢引起化学感受性反射,是低氧通气反应以及低氧血症引起循环系统一系列反应的关键.众所周知,外周和中枢化学感受器的交互作用在机体通气反应调节中至关重要,而且,颈动脉体的化学感受器活动在运动时的通气反应和体液调节中及高原地区慢性低氧所致的通气习服反应中起重要作用.在疾病状态下,如高血压、睡眠呼吸障碍(包括阻塞性睡眠呼吸暂停)和充血性心力衰竭的患者以及动物疾病模型中,化学感受器的活动及其反射的敏感性都显著提高.颈动脉体在生理状况下维持着机体的血氧稳定,在病理状况下参与了疾病的发展.因此,颈动脉体的细胞和分子调节机制可用来解释许多疾病的病理生理过程.%Peripheral chemoreceptors in the carotid body play a significant role in the transduction of chemical stimuli in the arterial blood notably hypoxia,hypercapnia and acidosis to the central for eliciting the chemoreflex,which is central to the hypoxic ventilatory response and is also important for the circulatory responses to hypoxia.It is known that interactions between the peripheral and central chemoreceptors are crucial to the magnitude of the reflex response for the ventilatory control.In addition,the carotid chemoreceptor activity contributes to the ventilatory and humoral responses to exercise and also significantly to the ventilatory acclimatization to chronic hypoxia at high altitude.Under diseased conditions,there are augmented chemoreceptor activity and chemoreflex sensitivity in patients with hypertension or sleep-disordered breathing including obstructive sleep apnea (OSA) and congestive heart failure and also in experimental animal models mimicking these diseases.Thus,the carotid body functions to maintain the oxygen homeostasis

  13. Functional Oxygen Sensitivity of Astrocytes.

    Science.gov (United States)

    Angelova, Plamena R; Kasymov, Vitaliy; Christie, Isabel; Sheikhbahaei, Shahriar; Turovsky, Egor; Marina, Nephtali; Korsak, Alla; Zwicker, Jennifer; Teschemacher, Anja G; Ackland, Gareth L; Funk, Gregory D; Kasparov, Sergey; Abramov, Andrey Y; Gourine, Alexander V

    2015-07-22

    In terrestrial mammals, the oxygen storage capacity of the CNS is limited, and neuronal function is rapidly impaired if oxygen supply is interrupted even for a short period of time. However, oxygen tension monitored by the peripheral (arterial) chemoreceptors is not sensitive to regional CNS differences in partial pressure of oxygen (PO2 ) that reflect variable levels of neuronal activity or local tissue hypoxia, pointing to the necessity of a functional brain oxygen sensor. This experimental animal (rats and mice) study shows that astrocytes, the most numerous brain glial cells, are sensitive to physiological changes in PO2 . Astrocytes respond to decreases in PO2 a few millimeters of mercury below normal brain oxygenation with elevations in intracellular calcium ([Ca(2+)]i). The hypoxia sensor of astrocytes resides in the mitochondria in which oxygen is consumed. Physiological decrease in PO2 inhibits astroglial mitochondrial respiration, leading to mitochondrial depolarization, production of free radicals, lipid peroxidation, activation of phospholipase C, IP3 receptors, and release of Ca(2+) from the intracellular stores. Hypoxia-induced [Ca(2+)]i increases in astrocytes trigger fusion of vesicular compartments containing ATP. Blockade of astrocytic signaling by overexpression of ATP-degrading enzymes or targeted astrocyte-specific expression of tetanus toxin light chain (to interfere with vesicular release mechanisms) within the brainstem respiratory rhythm-generating circuits reveals the fundamental physiological role of astroglial oxygen sensitivity; in low-oxygen conditions (environmental hypoxia), this mechanism increases breathing activity even in the absence of peripheral chemoreceptor oxygen sensing. These results demonstrate that astrocytes are functionally specialized CNS oxygen sensors tuned for rapid detection of physiological changes in brain oxygenation. Significance statement: Most, if not all, animal cells possess mechanisms that allow them to

  14. Fundamental constraints on the abundances of chemotaxis proteins

    CERN Document Server

    Bitbol, Anne-Florence

    2015-01-01

    Flagellated bacteria, such as Escherichia coli, perform directed motion in gradients of concentration of attractants and repellents in a process called chemotaxis. The E. coli chemotaxis signaling pathway is a model for signal transduction, but it has unique features. We demonstrate that the need for fast signaling necessitates high abundances of the proteins involved in this pathway. We show that further constraints on the abundances of chemotaxis proteins arise from the requirements of self-assembly, both of flagellar motors and of chemoreceptor arrays. All these constraints are specific to chemotaxis, and published data confirm that chemotaxis proteins tend to be more highly expressed than their homologs in other pathways. Employing a chemotaxis pathway model, we show that the gain of the pathway at the level of the response regulator CheY increases with overall chemotaxis protein abundances. This may explain why, at least in one E. coli strain, the abundance of all chemotaxis proteins is higher in media w...

  15. Participación del óxido nítrico, proteína Fos y el tallo cerebral en la retención de glucosa encefálica durante la hipoxia Involvement of the nitric oxide, Fos protein and brain stem in the retention of brain glucose during hypoxia

    Directory of Open Access Journals (Sweden)

    Mónica Lemus Vidal

    2009-12-01

    Full Text Available Se ha descrito que el núcleo del tracto solitario (NTS, estructura del tallo cerebral y vía de relevo de las aferencias del los quimiorreceptores del senocuerpo carotídeo (RSCC, participa en el aumento en la retención de glucosa por el cerebro (RGC ante una hipoxia. Es probable que en esta respuesta participe el óxido nítrico (NO y la proteína Fos. En este trabajo se analiza el papel del NO en el NTS sobre la modificación de la RGC y la expresión de la proteína inmunorreactiva Fos (Fos-ir en ratas in vivo. La inyección de un donador del NO como es el nitroprusiato de sodio (NPS en el NTS, 4 min antes de la estimulación de los RSCC, disminuyó la RGC, pero incrementó la expresión de Fos-ir en un mayor número de neuronas en el NTS con respecto a las ratas control, que sólo recibieron líquido cefalorraquídeo artificial (LCRa antes de la estimulación RSCC. En contraste, un inhibidor selectivo del NO como el N?-nitro-L-arginina metil éster (L-NAME en el NTS 4 min antes de la estimulación RSCC con NaCN, aumentó la RGC, pero disminuyó el número de neuronas Fos-ir comparados con el control o con NPS. La detección inmunohistoquímica de la expresión de Fos-ir en las células del tallo cerebral indica que la estimulación RSCC activa vías dependientes de NO en el NTS, para regular la RGC. El estudio de esta población de células en el NTS, será importante para definir su caracterización.It has been said that the nucleus tractus solitarii (NTS, one structure of the brain stem and path of apherences of chemoreceptors of carotid sinus-body, is involved in the increased glucose retention by the brain in case of hypoxia. It is likely that nitric oxide and Fos protein also take part in this response. This paper analyzes the role of nitric oxide in the NTS on the change of glucose retention by the brain and the expression of inmunoreactive protein Fos (ir-Fos in rats in vivo. The injection of a NO donor such as sodium nitroprusiate

  16. Hypoxic and hypercapnic challenges unveil respiratory vulnerability of Surf1 knockout mice, an animal model of Leigh syndrome.

    Science.gov (United States)

    Stettner, Georg M; Viscomi, Carlo; Zeviani, Massimo; Wilichowski, Ekkehard; Dutschmann, Mathias

    2011-05-01

    Surf1 gene mutations were detected as a main cause for Leigh syndrome (LS), also known as infantile subacute necrotizing encephalomyelopathy. This syndrome which is commonly associated with systemic cytochrome c oxidase (COX) deficiency manifests in early childhood and has an invariable poor prognosis. Progressive disturbances of the respiratory function, for which both the metabolic condition and necrotizing brainstem lesions contribute, belong to the major symptoms of LS. A constitutive knockout (KO) mouse for Surf1 enables invasive investigations of distinct aspects of LS. In the present study the respiratory function was analyzed applying an arterially perfused brainstem preparation. Compared to wild type (WT) preparations Surf1 KO preparations had a higher baseline respiratory frequency and abnormal responses to hypoxia and hypercapnia that involved both respiratory frequency and motor nerve discharge pattern. These data suggest that COX deficiency impairs peripheral and/or central chemoreceptor function. PMID:21167962

  17. Low cost of pulmonary ventilation in American alligators (Alligator mississippiensis) stimulated with doxapram.

    Science.gov (United States)

    Skovgaard, Nini; Crossley, Dane A; Wang, Tobias

    2016-04-01

    To determine the costs of pulmonary ventilation without imposing severe oxygen limitations or acidosis that normally accompany exposures to hypoxia or hypercapnia, we opted to pharmacologically stimulate ventilation with doxapram (5 and 10 mg kg(-1)) in alligators. Doxapram is used clinically to alleviate ventilatory depression in response to anaesthesia and acts primarily on the peripheral oxygen-sensitive chemoreceptors. Using this approach, we investigated the hypothesis that pulmonary ventilation is relatively modest in comparison to resting metabolic rate in crocodilians and equipped seven juvenile alligators with masks for concurrent determination of ventilation and oxygen uptake. Doxapram elicited a dose-dependent and up to fourfold rise in ventilation, primarily by increasing ventilatory frequency. The accompanying rise in oxygen uptake was very small; ventilation in resting animals constitutes no more than 5% of resting metabolic rate. The conclusion that pulmonary ventilation is energetically cheap is consistent with earlier studies on alligators where ventilation was stimulated by hypoxia or hypercapnia. PMID:26896538

  18. Existence of a sex pheromone in Triatoma infestans (Hemiptera: Reduvidae: II. Electrophysiological correlates

    Directory of Open Access Journals (Sweden)

    Maria G. de Brito Sanchez

    1995-10-01

    Full Text Available The stimulus provided by a copulating pair of Triatoma infestans significantly affects the electrical activity of the nervous system of Triatoma infestans. Electrophysiological recordings were perfomed on stationary adult males presented with stimuli of an air current carrying odors from males, females, non-copulating pairs and mating pairs. The electrophysiological response was characterized by the low frequency occurrence of biphasic compound impulses. A significant increase in the frequency of the impulses occurred in stationary males when exposed to air currents of mating pairs, when compared to that evoked by a clean air stream. Analysis of the time course of the assays, showed that the electrophisiological activity during the copula was higher than prior to or after copula. The electrophysiological evidence presented here strongly supports the existence of pheromone(s released by one or both sexes during mating and which is perceived by male chemoreceptors located on the antennae.

  19. Mathematical modelling of a human external respiratory system

    Science.gov (United States)

    1977-01-01

    A closed system of algebraic and common differential equations solved by computer is investigated. It includes equations which describe the activity pattern of the respiratory center, the phrenic nerve, the thrust produced by the diaphragm as a function of the lung volume and discharge frequency of the phrenic nerve, as well as certain relations of the lung stretch receptors and chemoreceptors on various lung and blood characteristics, equations for lung biomechanics, pulmonary blood flow, alveolar gas exchange and capillary blood composition equations to determine various air and blood flow and gas exchange parameters, and various gas mixing and arterial and venous blood composition equations, to determine other blood, air and gas mixing characteristics. Data are presented by means of graphs and tables, and some advantages of this model over others are demonstrated by test results.

  20. Principles of agonist recognition in Cys-loop receptors

    Directory of Open Access Journals (Sweden)

    Timothy eLynagh

    2014-04-01

    Full Text Available Cys-loop receptors are ligand-gated ion channels that are activated by a structurally diverse array of neurotransmitters, including acetylcholine, serotonin, glycine and GABA. After the term chemoreceptor emerged over 100 years ago, there was some wait until affinity labeling, molecular cloning, functional studies and X-ray crystallography experiments identified the extracellular interface of adjacent subunits as the principal site of agonist binding. The question of how subtle differences at and around agonist-binding sites of different Cys-loop receptors can accommodate transmitters as chemically diverse as glycine and serotonin has been subject to intense research over the last three decades. This review outlines the functional diversity and current structural understanding of agonist-binding sites, including those of invertebrate Cys-loop receptors. Together, this provides a framework to understand the atomic determinants involved in how these valuable therapeutic targets recognize and bind their ligands.

  1. Retrotrapezoid nucleus, respiratory chemosensitivity and breathing automaticity

    Science.gov (United States)

    Guyenet, Patrice G.; Bayliss, Douglas A.; Stornetta, Ruth L.; Fortuna, Michal G.; Abbott, Stephen B.; Depuy, Seth D.

    2009-01-01

    SUMMARY Breathing automaticity and CO2 regulation are inseparable neural processes. The retrotrapezoid nucleus (RTN), a group of glutamatergic neurons that express the transcription factor Phox2b, may be a crucial nodal point through which breathing automaticity is regulated to maintain CO2 constant. This review updates the analysis presented in prior publications. Additional evidence that RTN neurons have central respiratory chemoreceptor properties is presented but this is only one of many factors that determine their activity. The RTN is also regulated by powerful inputs from the carotid bodies and, at least in the adult, by many other synaptic inputs. We also analyze how RTN neurons may control the activity of the downstream central respiratory pattern generator. Specifically, we review the evidence which suggests that RTN neurons a) innervate the entire ventral respiratory column, and b) control both inspiration and expiration. Finally, we argue that the RTN neurons are the adult form of the parafacial respiratory group in neonate rats. PMID:19712903

  2. On the correlation of moth flight to characteristics of a turbulent plume

    CERN Document Server

    Hadad, Tal; Liberzon, Alex; Gurka, Roi

    2013-01-01

    Several mechanisms control male moth's navigation towards a female releasing sex pheromone. Optomotor anemotaxis is a visual mechanism for the moth flight direction relative to the ground, mechanoreceptors are used for calculating its speed relative to the air current and chemoreceptors on the antennae for sampling the pheromone concentration in the air. All together result in a zigzagging flight pattern of the male moth that depends on the characteristics of its encounters with the pheromone plume. The zigzagging flight pattern includes constant counter-turnings across the wind line in an angle up to 90 degree (casting). In this paper we address how air turbulence manifests the male flight behavior in respect to the streamwise current that carries the pheromone, emphasizing a relationship between the flight speed and the turbulent plume properties. The interaction between the moth flight and the flow field characteristics was examined in a wind tunnel where moth trajectory was recorded. Particle image veloci...

  3. Evidence nitric oxide mediates the vasodepressor response to hypoxia in sino-denervated rats

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Miaokun; Reis, D.J. (Cornell Univ., New York, NY (United States))

    1992-01-01

    Systemic hypoxia, produced in deeply anesthetized, paralyzed rats in which arterial chemoreceptors were denervated, elicited a decrease in arterial pressure (AP) averaging {minus}47 mmHg. Systemic administration of N{sup G}-nitro-L-arginine (L-NO{sub 2}Arg), inhibitor of nitric oxide (NO) synthase, attenuated the hypoxic depressor response by 79% and elevated AP by 21 mmHg. The effects of L-NO{sub 2}Arg on the hypoxic depressor response and arterial pressure were reversed by systemic administration of L- but not D-arginine. Elevation of AP with arginine-vasopressin or reduction of AP with nitroprusside to the pre-L-NO{sub 2}Arg levels did not modify the fall of AP to hypoxia. Endogenous NO synthesized in vivo from L-arginine, mediates most of the hypoxia depressor response.

  4. Assembly of the transmembrane domain of E. coli PhoQ histidine kinase: implications for signal transduction from molecular simulations.

    Directory of Open Access Journals (Sweden)

    Thomas Lemmin

    Full Text Available The PhoQP two-component system is a signaling complex essential for bacterial virulence and cationic antimicrobial peptide resistance. PhoQ is the histidine kinase chemoreceptor of this tandem machine and assembles in a homodimer conformation spanning the bacterial inner membrane. Currently, a full understanding of the PhoQ signal transduction is hindered by the lack of a complete atomistic structure. In this study, an atomistic model of the key transmembrane (TM domain is assembled by using molecular simulations, guided by experimental cross-linking data. The formation of a polar pocket involving Asn202 in the lumen of the tetrameric TM bundle is crucial for the assembly and solvation of the domain. Moreover, a concerted displacement of the TM helices at the periplasmic side is found to modulate a rotation at the cytoplasmic end, supporting the transduction of the chemical signal through a combination of scissoring and rotational movement of the TM helices.

  5. Pathophysiology of Resistant Hypertension: The Role of Sympathetic Nervous System

    Directory of Open Access Journals (Sweden)

    Costas Tsioufis

    2011-01-01

    Full Text Available Resistant hypertension (RH is a powerful risk factor for cardiovascular morbidity and mortality. Among the characteristics of patients with RH, obesity, obstructive sleep apnea, and aldosterone excess are covering a great area of the mosaic of RH phenotype. Increased sympathetic nervous system (SNS activity is present in all these underlying conditions, supporting its crucial role in the pathophysiology of antihypertensive treatment resistance. Current clinical and experimental knowledge points towards an impact of several factors on SNS activation, namely, insulin resistance, adipokines, endothelial dysfunction, cyclic intermittent hypoxaemia, aldosterone effects on central nervous system, chemoreceptors, and baroreceptors dysregulation. The further investigation and understanding of the mechanisms leading to SNS activation could reveal novel therapeutic targets and expand our treatment options in the challenging management of RH.

  6. Almitrine has no effect on gas exchange after bilateral carotid body resection in severe chronic airflow obstruction.

    Science.gov (United States)

    De Backer, W; Vermeire, P; Bogaert, E; Janssens, E; Van Maele, R

    1985-01-01

    Using a double-blind cross-over design, a single dose of 100 mg almitrine bismesylate and placebo were administered orally to eight patients with chronic airflow obstruction having undergone bilateral carotid body resection (BCBR) up to two years earlier to alleviate their extreme dyspnoea. In an open study, two other patients have been given almitrine before and three weeks after BCBR. In all patients, arterial blood gases, ventilation and breathing patterns, neuromuscular drive and hypoxic responsiveness have been studied before and three hours after drug administration. Almitrine failed to improve gas exchange in the patients with BCBR, nor did it affect ventilation, ventilatory or hypoxic drive. In the patients studied before and after BCBR, almitrine only improved gas exchange significantly before BCBR. It is concluded that in man almitrine acts solely as a peripheral chemoreceptor agonist and that the well-documented improvement in V/Q relationship is mediated through carotid body stimulation. PMID:3904873

  7. The mysterious multi-modal repellency of DEET

    Science.gov (United States)

    DeGennaro, Matthew

    2015-01-01

    DEET is the most effective insect repellent available and has been widely used for more than half a century. Here, I review what is known about the olfactory and contact mechanisms of DEET repellency. For mosquitoes, DEET has at least two molecular targets: Odorant Receptors (ORs) mediate the effect of DEET at a distance, while unknown chemoreceptors mediate repellency upon contact. Additionally, the ionotropic receptor Ir40a has recently been identified as a putative DEET chemosensor in Drosophila. The mechanism of how DEET manipulates these molecular targets to induce insect avoidance in the vapor phase is also contested. Two hypotheses are the most likely: DEET activates an innate olfactory neural circuit leading to avoidance of hosts (smell and avoid hypothesis) or DEET has no behavioral effect on its own, but instead acts cooperatively with host odors to drive repellency (confusant hypothesis). Resolving this mystery will inform the search for a new generation of insect repellents. PMID:26252744

  8. Hemodynamic and ventilatory response to different levels of hypoxia and hypercapnia in carotid body-denervated rats

    Directory of Open Access Journals (Sweden)

    João Paulo J. Sabino

    2013-01-01

    Full Text Available OBJECTIVE: Chemoreceptors play an important role in the autonomic modulation of circulatory and ventilatory responses to changes in arterial O2 and/or CO2. However, studies evaluating hemodynamic responses to hypoxia and hypercapnia in rats have shown inconsistent results. Our aim was to evaluate hemodynamic and respiratory responses to different levels of hypoxia and hypercapnia in conscious intact or carotid body-denervated rats. METHODS: Male Wistar rats were submitted to bilateral ligature of carotid body arteries (or sham-operation and received catheters into the left femoral artery and vein. After two days, each animal was placed into a plethysmographic chamber and, after baseline measurements of respiratory parameters and arterial pressure, each animal was subjected to three levels of hypoxia (15, 10 and 6% O2 and hypercapnia (10% CO2. RESULTS: The results indicated that 15% O2 decreased the mean arterial pressure and increased the heart rate (HR in both intact (n = 8 and carotid body-denervated (n = 7 rats. In contrast, 10% O2did not change the mean arterial pressure but still increased the HR in intact rats, and it decreased the mean arterial pressure and increased the heart rate in carotid body-denervated rats. Furthermore, 6% O2 increased the mean arterial pressure and decreased the HR in intact rats, but it decreased the mean arterial pressure and did not change the HR in carotid body-denervated rats. The 3 levels of hypoxia increased pulmonary ventilation in both groups, with attenuated responses in carotid body-denervated rats. Hypercapnia with 10% CO2 increased the mean arterial pressure and decreased HR similarly in both groups. Hypercapnia also increased pulmonary ventilation in both groups to the same extent. CONCLUSION: This study demonstrates that the hemodynamic and ventilatory responses varied according to the level of hypoxia. Nevertheless, the hemodynamic and ventilatory responses to hypercapnia did not depend on the

  9. Branchial receptors and cardiorespiratory reflexes in a neotropical fish, the tambaqui (Colossoma macropomum).

    Science.gov (United States)

    Sundin, L; Reid, S G; Rantin, F T; Milsom, W K

    2000-04-01

    This study examined the location and physiological roles of branchial chemoreceptors involved in the cardiorespiratory responses to hypoxia and hypercarbia in a neotropical fish that exhibits aquatic surface respiration, the tambaqui (Colossoma macropomum). Fish were exposed to abrupt progressive environmental hypoxia (18. 6-1.3 kPa water P(O2)) and hypercarbia (water equilibrated with 5 % CO(2) in air, which lowered the water pH from 7.0 to 5.0). They were also subjected to injections of NaCN into the ventral aorta (to stimulate receptors monitoring the blood) and buccal cavity (to stimulate receptors monitoring the respiratory water). All tests were performed before and after selective denervation of branchial branches of cranial nerves IX and X to the gill arches. The data suggest that the O(2) receptors eliciting reflex bradycardia and increases in breathing frequency are situated on all gill arches and sense changes in both the blood and respiratory water and that the O(2) receptors triggering the elevation in systemic vascular resistance, breathing amplitude, swelling of the inferior lip and that induce aquatic surface respiration during hypoxia are extrabranchial, although branchial receptors also contribute to the latter two responses. Hypercarbia also produced bradycardia and increases in breathing frequency, as well as hypertension, and, while the data suggest that there may be receptors uniquely sensitive to changes in CO(2)/pH involved in cardiorespiratory control, this is based on quantitative rather than qualitative differences in receptor responses. These data reveal yet another novel combination for the distribution of cardiorespiratory chemoreceptors in fish from which teleologically satisfying trends have yet to emerge. PMID:10708642

  10. Chemosensitivity, Cardiovascular Risk, and the Ventilatory Response to Exercise in COPD.

    Directory of Open Access Journals (Sweden)

    Michael K Stickland

    Full Text Available COPD is associated with elevated cardiovascular risk and a potentiated ventilatory response to exercise. Enhanced carotid chemoreceptor (CC activity/sensitivity is present in other clinical conditions, has been shown to contribute to sympathetic vasoconstrictor outflow, and is predictive of mortality. CC activity/sensitivity, and the resulting functional significance, has not been well examined in COPD. We hypothesized that CC activity/sensitivity would be elevated in COPD, and related to increased pulse wave velocity (a marker of CV risk and the ventilatory response to exercise.30 COPD patients and 10 healthy age-matched controls were examined. Participants performed baseline cardiopulmonary exercise and pulmonary function testing. CC activity was later evaluated by the drop in ventilation with breathing 100% O2, and CC sensitivity was then assessed by the ventilatory response to hypoxia (ΔVE/ΔSpO2. Peripheral arterial stiffness was subsequently evaluated by measurement of pulse wave velocity (PWV using applanation tonometry while the subjects were breathing room air, and then following chemoreceptor inhibition by breathing 100% O2 for 2 minutes.CC activity, CC sensitivity, PWV and the ventilatory response to exercise were all increased in COPD relative to controls. CC sensitivity was related to PWV; however, neither CC activity nor CC sensitivity was related to the ventilatory response to exercise in COPD. CC inhibition by breathing 100% O2 normalized PWV in COPD, while no effect was observed in controls.CC activity and sensitivity are elevated in COPD, and appear related to cardiovascular risk; however, CC activity/sensitivity does not contribute to the potentiated ventilatory response to exercise.

  11. Central CO2 chemoreception and integrated neural mechanisms of cardiovascular and respiratory control

    Science.gov (United States)

    Stornetta, Ruth L.; Abbott, Stephen B. G.; Depuy, Seth D.; Fortuna, Michal G.; Kanbar, Roy

    2010-01-01

    In this review, we examine why blood pressure (BP) and sympathetic nerve activity (SNA) increase during a rise in central nervous system (CNS) Pco2 (central chemoreceptor stimulation). CNS acidification modifies SNA by two classes of mechanisms. The first one depends on the activation of the central respiratory controller (CRG) and causes the much-emphasized respiratory modulation of the SNA. The CRG probably modulates SNA at several brain stem or spinal locations, but the most important site of interaction seems to be the caudal ventrolateral medulla (CVLM), where unidentified components of the CRG periodically gate the baroreflex. CNS Pco2 also influences sympathetic tone in a CRG-independent manner, and we propose that this process operates differently according to the level of CNS Pco2. In normocapnia and indeed even below the ventilatory recruitment threshold, CNS Pco2 exerts a tonic concentration-dependent excitatory effect on SNA that is plausibly mediated by specialized brain stem chemoreceptors such as the retrotrapezoid nucleus. Abnormally high levels of Pco2 cause an aversive interoceptive awareness in awake individuals and trigger arousal from sleep. These alerting responses presumably activate wake-promoting and/or stress-related pathways such as the orexinergic, noradrenergic, and serotonergic neurons. These neuronal groups, which may also be directly activated by brain acidification, have brainwide projections that contribute to the CO2-induced rise in breathing and SNA by facilitating neuronal activity at innumerable CNS locations. In the case of SNA, these sites include the nucleus of the solitary tract, the ventrolateral medulla, and the preganglionic neurons. PMID:20075262

  12. Effects of hypercapnia and hypocapnia on ventilatory variability and the chaotic dynamics of ventilatory flow in humans.

    Science.gov (United States)

    Fiamma, Marie-Noëlle; Straus, Christian; Thibault, Sylvain; Wysocki, Marc; Baconnier, Pierre; Similowski, Thomas

    2007-05-01

    In humans, lung ventilation exhibits breath-to-breath variability and dynamics that are nonlinear, complex, sensitive to initial conditions, unpredictable in the long-term, and chaotic. Hypercapnia, as produced by the inhalation of a CO(2)-enriched gas mixture, stimulates ventilation. Hypocapnia, as produced by mechanical hyperventilation, depresses ventilation in animals and in humans during sleep, but it does not induce apnea in awake humans. This emphasizes the suprapontine influences on ventilatory control. How cortical and subcortical commands interfere thus depend on the prevailing CO(2) levels. However, CO(2) also influences the variability and complexity of ventilation. This study was designed to describe how this occurs and to test the hypothesis that CO(2) chemoreceptors are important determinants of ventilatory dynamics. Spontaneous ventilatory flow was recorded in eight healthy subjects. Breath-by-breath variability was studied through the coefficient of variation of several ventilatory variables. Chaos was assessed with the noise titration method (noise limit) and characterized with numerical indexes [largest Lyapunov exponent (LLE), sensitivity to initial conditions; Kolmogorov-Sinai entropy (KSE), unpredictability; and correlation dimension (CD), irregularity]. In all subjects, under all conditions, a positive noise limit confirmed chaos. Hypercapnia reduced breathing variability, increased LLE (P = 0.0338 vs. normocapnia; P = 0.0018 vs. hypocapnia), increased KSE, and slightly reduced CD. Hypocapnia increased variability, decreased LLE and KSE, and reduced CD. These results suggest that chemoreceptors exert a strong influence on ventilatory variability and complexity. However, complexity persists in the quasi-absence of automatic drive. Ventilatory variability and complexity could be determined by the interaction between the respiratory central pattern generator and suprapontine structures. PMID:17218438

  13. Carotid body, insulin and metabolic diseases: unravelling the links

    Directory of Open Access Journals (Sweden)

    Silvia V Conde

    2014-10-01

    Full Text Available The carotid bodies (CB are peripheral chemoreceptors that sense changes in arterial blood O2, CO2 and pH levels. Hypoxia, hypercapnia and acidosis activate the CB, which respond by increasing the action potential frequency in their sensory nerve, the carotid sinus nerve (CSN. CSN activity is integrated in the brain stem to induce a panoply of cardiorespiratory reflexes aimed, primarily, to normalize the altered blood gases, via hyperventilation, and to regulate blood pressure and cardiac performance, via sympathetic nervous system (SNS activation. Besides its role in the cardiorespiratory control the CB has been proposed as a metabolic sensor implicated in the control of energy homeostasis and, more recently, in the regulation of whole body insulin sensitivity. Hypercaloric diets cause CB overactivation in rats, which seems to be at the origin of the development of insulin resistance and hypertension, core features of metabolic syndrome and type 2 diabetes. Consistent with this notion, CB sensory denervation prevents metabolic and hemodynamic alterations in hypercaloric feed animal. Obstructive sleep apnoea (OSA is another chronic disorder characterized by increased CB activity and intimately related with several metabolic and cardiovascular abnormalities. In this manuscript we review in a concise manner the putative pathways linking CB chemoreceptors deregulation with the pathogenesis of insulin resistance and arterial hypertension. Also, the link between chronic intermittent hypoxia (CIH and insulin resistance is discussed. Then, a final section is devoted to debate strategies to reduce CB activity and its use for prevention and therapeutics of metabolic diseases with an emphasis on new exciting research in the modulation of bioelectronic signals, likely to be central in the future.

  14. Hypoxia and electrical stimulation of the carotid sinus nerve induce Fos-like immunoreactivity within catecholaminergic and serotoninergic neurons of the rat brainstem.

    Science.gov (United States)

    Erickson, J T; Millhorn, D E

    1994-10-01

    A complete understanding of the neural mechanisms responsible for the chemoreceptor and baroreceptor reflexes requires precise knowledge of the locations and chemical phenotypes of higher-order neurons within these reflex pathways. In the present study, the protein product (Fos) of the c-fos protooncogene was used as a metabolic marker to trace central neural pathways following activation of carotid sinus nerve afferent fibers. In addition, immunohistochemical double-labeling techniques were used to define the chemical phenotypes of activated neurons. Both electrical stimulation of the carotid sinus nerve and physiological stimulation of the carotid bodies by hypoxia induced Fos-like immunoreactivity in catecholaminergic neurons containing tyrosine hydroxylase or phenylethanolamine-N-methyltransferase in the ventrolateral medulla oblongata and, to a lesser degree, in the dorsal vagal complex. Tyrosine hydroxylase/Fos colocalization was also observed in the locus coeruleus and the A5 noradrenergic cell group in pons. Many serotoninergic neurons in nucleus raphe pallidus, nucleus raphe magnus, and along the ventral medullary surface contained Fos-like immunoreactivity. In pons and midbrain, Fos-like immunoreactivity was observed in the lateral parabrachial and Kölliker-Fuse nuclei, the inferior colliculus, the cuneiform nucleus, and in the vicinity of the Edinger-Westphal nucleus, but no catecholaminergic or serotoninergic colocalization was observed in these regions. Although Fos-labeled cells were observed within and lateral to the dorsal raphe nucleus, few were catecholaminergic or serotoninergic. This study further defines a potential central neuroanatomical substrate for the chemoreceptor and/or baroreceptor reflexes. PMID:7814687

  15. 线虫转型发育和寄主识别的化学通讯研究进展%Research progress on chemical communication of development and host-finding of nematodes

    Institute of Scientific and Technical Information of China (English)

    张宾; 胡春祥; 石进; 蒋丽雅; 汤宗斌; 石敬夫; 赵莉蔺

    2013-01-01

    Nematodes are globally distributed invertebrates, which are often found living in soil or as parasites of animals, insects and plants. They lack vision and hearing systems, so the survival of both free-living and parasitic nematodes depends on well developed chemosensation and chemotaxis systems. Nematodes utilize chemical signals in their environment to detect food sources, potential hosts, noxious compounds, reproductive partners and sometimes to enable them to choose between alternative developmental states. Interest in the mechanisms involved in chemosensing and identification of the discrete components of the chemical signals has steadily increased over the past few decades. Here we have summarized and evaluated recent discoveries and advances in this field, involving the mechanism of developmental regulation, the recognition of hosts, the construction and function of the chemoreceptor system, signal transduction, the prospects for related research and the control of harmful nematodes based on chemical ecology. The pheromonal cues that indicate overcrowding, high temperature, or starvation can trigger the nematodes to enter into diapause and enhance longevity by modulating endocrine signaling and gene expression. The genetic and molecular basis of phenotypic plasticity has been studied extensively in Caenorhabditis elegans, and recently, it was discovered that pheromones called ascarosides secreted by C. elegans themselves induce formation of the dauer stage and the four chemoreceptors of the dauer juveniles. Recognition of hosts by nematodes is very specific and the chemical signals from the hosts, as well as the chemoreceptors of the nematodes play key roles in this process. Both free-living and parasitic nematodes can sense chemical signals comprised of water soluble and/or volatile compounds. The chemotaxis of C. elegans has been studied for over 30 years and inducing substances identified thus far include salt ion ( Na+、Li+、Cl-、OH- ) , amino acid

  16. Differences in the control of breathing between Himalayan and sea-level residents

    Science.gov (United States)

    Slessarev, M; Prisman, E; Ito, S; Watson, R R; Jensen, D; Preiss, D; Greene, R; Norboo, T; Stobdan, T; Diskit, D; Norboo, A; Kunzang, M; Appenzeller, O; Duffin, J; Fisher, J A

    2010-01-01

    We compared the control of breathing of 12 male Himalayan highlanders with that of 21 male sea-level Caucasian lowlanders using isoxic hyperoxic (= 150 mmHg) and hypoxic (= 50 mmHg) Duffin's rebreathing tests. Highlanders had lower mean ±s.e.m. ventilatory sensitivities to CO2 than lowlanders at both isoxic tensions (hyperoxic: 2.3 ± 0.3 vs. 4.2 ± 0.3 l min−1 mmHg−1, P= 0.021; hypoxic: 2.8 ± 0.3 vs. 7.1 ± 0.6 l min−1 mmHg−1, P < 0.001), and the usual increase in ventilatory sensitivity to CO2 induced by hypoxia in lowlanders was absent in highlanders (P= 0.361). Furthermore, the ventilatory recruitment threshold (VRT) CO2 tensions in highlanders were lower than in lowlanders (hyperoxic: 33.8 ± 0.9 vs. 48.9 ± 0.7 mmHg, P < 0.001; hypoxic: 31.2 ± 1.1 vs. 44.7 ± 0.7 mmHg, P < 0.001). Both groups had reduced ventilatory recruitment thresholds with hypoxia (P < 0.001) and there were no differences in the sub-threshold ventilations (non-chemoreflex drives to breathe) between lowlanders and highlanders at both isoxic tensions (P= 0.982), with a trend for higher basal ventilation during hypoxia (P= 0.052). We conclude that control of breathing in Himalayan highlanders is distinctly different from that of sea-level lowlanders. Specifically, Himalayan highlanders have decreased central and absent peripheral sensitivities to CO2. Their response to hypoxia was heterogeneous, with the majority decreasing their VRT indicating either a CO2-independent increase in activity of peripheral chemoreceptor or hypoxia-induced increase in [H+] at the central chemoreceptor. In some highlanders, the decrease in VRT was accompanied by an increase in sensitivity to CO2, while in others VRT remained unchanged and their sub-threshold ventilations increased, although these were not statistically significant. PMID:20194122

  17. Two different mechanisms mediate chemotaxis to inorganic phosphate in Pseudomonas aeruginosa

    Science.gov (United States)

    Rico-Jiménez, Miriam; Reyes-Darias, Jose Antonio; Ortega, Álvaro; Díez Peña, Ana Isabel; Morel, Bertrand; Krell, Tino

    2016-01-01

    Inorganic phosphate (Pi) is a central signaling molecule that modulates virulence in various pathogens. In Pseudomonas aeruginosa, low Pi concentrations induce transcriptional alterations that increase virulence. Also, under low Pi levels, P. aeruginosa exhibits Pi chemotaxis—a process mediated by the two non-paralogous receptors CtpH and CtpL. Here we show that the two receptors operate via different mechanisms. We demonstrate that the ligand binding domain (LBD) of CtpH but not CtpL binds Pi directly. We identify the periplasmic ligand binding protein PstS as the protein that binds in its Pi loaded state to CtpL, resulting in receptor stimulation. PstS forms part of the Pi transporter and has thus a double function in Pi transport and chemotaxis. The affinity of Pi for CtpH was modest whereas that for PstS very high, which may explain why CtpH and CtpL mediate chemotaxis to high and low Pi concentrations, respectively. The pstS/ctpH double mutant was almost devoid of Pi taxis, indicating that PstS is the only CtpL Pi-shuttle. Chemotaxis mechanisms based on indirect ligand recognition were unambiguously identified in enterobacteria. The discovery of a similar mechanism in a different bacterial order, involving a different chemoreceptor type and chemoeffector suggests that such systems are widespread. PMID:27353565

  18. SUNCT syndrome: The materialization of a headache syndrome

    Directory of Open Access Journals (Sweden)

    Ottar Sjaastad

    2008-10-01

    Full Text Available Ottar SjaastadDepartment of Neurology, St. Olav´s Hospital, 7006 Trondheim University Hospitals, Trondheim, NorwayAbstract: Shortlasting, unilateral, neuralgiform headache attacks with conjunctival injection and tearing (SUNCT syndrome is a rare headache, described by our group in 1989. This overview presents our early studies of SUNCT pathogenesis. Due to the conspicuous ictal, ocular phenomena, ie, conjunctival injection and tearing, our studies started out with ocular parameters: intraocular pressure and corneal indentation pulse amplitudes, both of which showed clear ictal increments, symptomatic side. Beat-to-beat, noninvasive blood pressure measurements during attack showed instant, systolic blood pressure rise and corresponding pulse rate decrease. Carotid body, the principal peripheral chemoreceptor, seemed to function normally. The middle cerebral artery was dilated during attacks, particularly on the symptomatic side. Finally, some viewpoints are added regarding terminology. SUNCT is a workable and accepted term. There does not seem to be any need for another, fictitious term to describe the same clinical picture.Keywords: SUNCT syndrome, intraocular blood flow, intraocular pressure, median artery blood flow, carotid body function, hypothalamic stimulation

  19. The G. L. Brown Prize Lecture. Hypoxic regulation of ion channel function and expression.

    Science.gov (United States)

    Peers, Chris

    2002-07-01

    Acute hypoxia regulates the activity of specific ion channels in a rapid and reversible manner. Such effects underlie appropriate cellular responses to hypoxia which are designed to initiate cardiorespiratory reflexes and contribute importantly to other tissue responses, all of which are designed to improve tissue O2 supply. These responses include excitation of chemoreceptors as well as pulmonary vasoconstriction and systemic vasodilatation. However, such responses may also contribute to the adverse responses to hypoxia, such as excitotoxicity in the central nervous system. Whilst numerous ion channel types are known to be modulated by acute hypoxia, the nature of the O2 sensor in most tissues remains to be identified. Prolonged (chronic) hypoxia regulates functional expression of ion channels, and so remodels excitability of various cell types. Whilst this may contribute to adaptive responses such as high-altitude acclimatization, such altered channel expression may also contribute to the onset of pathological disorders, including Alzheimer's disease. Indeed, evidence is emerging that production of pathological peptides associated with Alzheimer's disease is increased during prolonged hypoxia. Such effects may account for the known increased incidence of this disease in patients who have previously endured hypoxic episodes, such as congestive heart failure and stroke. Identification of the mechanisms coupling hypoxia to the increased production of these peptides is likely to be of therapeutic benefit. PMID:12392105

  20. Major Autonomic Neuroregulatory Pathways Underlying Short- and Long-Term Control of Cardiovascular Function.

    Science.gov (United States)

    Salman, Ibrahim M

    2016-03-01

    Short-term and long-term blood pressure (BP) regulation and its maintenance at levels adequate to perfuse tissue organs involve an integrated action of multiple neural, cardiovascular, renal, endocrine and local tissue control systems. In the recent year, there has been a growing interest in the understanding of neural pathways key to BP control. For instance, through major advances in studies using both anesthetized and conscious animals, our knowledge of the essential neural mechanisms that subserve the baroreceptor, cardiopulmonary and chemoreceptor reflexes, and those evoked by the activation of stress pathways has dramatically increased. While the importance of these neural pathways in the maintenance of cardiovascular homeostasis is well established, the recognition of the central processing nuclei that integrate various afferent inputs to produce synchronous adjustments of autonomic outflows is still progressively expanding. Based on the literature provided thus far, the present review provides an overview in relation to the important neural determinants of BP control and later offers a concise description of major neuronal pathways that control autonomic outflows to the cardiovascular system in the short and long term. PMID:26838031

  1. The Contributions of Paul Ehrlich to Pharmacology: A Tribute on the Occasion of the Centenary of His Nobel Prize

    Science.gov (United States)

    Bosch, Fèlix; Rosich, Laia

    2008-01-01

    On the centenary of Paul Ehrlich's Nobel Prize, this German researcher deserves to be remembered as a pioneer in a large number of scientific disciplines. As a result of his enthusiasm and scientific abilities, dedication, and contacts with other scientists of his time, he was able to make countless contributions in fields as diverse as histology, haematology, immunology, oncology, microbiology and pharmacology, among others. Although the Swedish award was meant to recognize the standardization of the manufacture of antidiphtheria serum, it was the discovery of arsphenamine (Salvarsan) for the treatment of syphilis which won him wider international acclaim. From a pharmacological perspective, Ehrlich's outstanding contributions include dissemination of the ‘magic bullet’ concept for the synthesis of antibacterials, introduction of concepts such as chemoreceptor and chemotherapy, and linking the chemical structure of compounds to their pharmacological activity. These achievements took place within the framework he established for the transition from experimental pharmacology to therapeutic pharmacology. He introduced a modern research system based on the synthesis of multiple chemical structures for pharmacological screening in animal models of disease states. These contributions were undoubtedly decisive in propitiating the wider development of antibiotics decades later. For these reasons, it is fitting to mark the 100th anniversary of the Nobel Prize awarded to this great scientist by commemorating the importance of his contributions to the advance of pharmacology. PMID:18679046

  2. Genome Evolution in the Obligate but Environmentally Active Luminous Symbionts of Flashlight Fish.

    Science.gov (United States)

    Hendry, Tory A; de Wet, Jeffrey R; Dougan, Katherine E; Dunlap, Paul V

    2016-01-01

    The luminous bacterial symbionts of anomalopid flashlight fish are thought to be obligately dependent on their hosts for growth and share several aspects of genome evolution with unrelated obligate symbionts, including genome reduction. However, in contrast to most obligate bacteria, anomalopid symbionts have an active environmental phase that may be important for symbiont transmission. Here we investigated patterns of evolution between anomalopid symbionts compared with patterns in free-living relatives and unrelated obligate symbionts to determine if trends common to obligate symbionts are also found in anomalopid symbionts. Two symbionts, "Candidatus Photodesmus katoptron" and "Candidatus Photodesmus blepharus," have genomes that are highly similar in gene content and order, suggesting genome stasis similar to ancient obligate symbionts present in insect lineages. This genome stasis exists in spite of the symbiont's inferred ability to recombine, which is frequently lacking in obligate symbionts with stable genomes. Additionally, we used genome comparisons and tests of selection to infer which genes may be particularly important for the symbiont's ecology compared with relatives. In keeping with obligate dependence, substitution patterns suggest that most symbiont genes are experiencing relaxed purifying selection compared with relatives. However, genes involved in motility and carbon storage, which are likely to be used outside the host, appear to be under increased purifying selection. Two chemoreceptor chemotaxis genes are retained by both species and show high conservation with amino acid sensing genes, suggesting that the bacteria may actively seek out hosts using chemotaxis toward amino acids, which the symbionts are not able to synthesize. PMID:27389687

  3. Language of plants: Where is the word?

    Science.gov (United States)

    Šimpraga, Maja; Takabayashi, Junji; Holopainen, Jarmo K

    2016-04-01

    Plants emit biogenic volatile organic compounds (BVOCs) causing transcriptomic, metabolomic and behavioral responses in receiver organisms. Volatiles involved in such responses are often called "plant language". Arthropods having sensitive chemoreceptors can recognize language released by plants. Insect herbivores, pollinators and natural enemies respond to composition of volatiles from plants with specialized receptors responding to different types of compounds. In contrast, the mechanism of how plants "hear" volatiles has remained obscured. In a plant-plant communication, several individually emitted compounds are known to prime defense response in receiver plants with a specific manner according to the chemical structure of each volatile compound. Further, composition and ratio of volatile compounds in the plant-released plume is important in plant-insect and plant-plant interactions mediated by plant volatiles. Studies on volatile-mediated plant-plant signaling indicate that the signaling distances are rather short, usually not longer than one meter. Volatile communication from plants to insects such as pollinators could be across distances of hundreds of meters. As many of the herbivore induced VOCs have rather short atmospheric life times, we suggest that in long-distant communications with plant volatiles, reaction products in the original emitted compounds may have additional information value of the distance to emission source together with the original plant-emitted compounds. PMID:26563972

  4. Changing reactivity of receptor carboxyl groups during bacterial sensing.

    Science.gov (United States)

    Stock, J B; Koshland, D E

    1981-11-10

    A microdistillation procedure has been developed to analyze carboxylmethylation of the Mr = 60,000 chemoreceptor proteins involved in chemotaxis of Salmonella typhimurium and Escherichia coli. Methylation levels obtained by this method are substantially higher than those reported in the literature. In highly motile strains under optimal conditions there are approximately 100,000 methylated receptor residues per cell which are entirely composed of gamma-methylglutamyl esters. Whereas with previously used methods only groups which turn over could be detected, the microdistillation assay provides absolute values. Under steady state conditions, approximately one-half the total number of methyl ester residues are continuously hydrolyzed and resynthesized, while the remainder are sequestered. A mechanism has been devised to explain the observed patterns of methyl ester synthesis and hydrolysis. According to this hypothesis, substrate glutamyl residues on the receptor are located in a restricted region near the active sites of transferase and esterase which are bound to the receptor protein. Small, stimuli-induced changes in receptor conformation effect perturbations in receptor methylation by shifting the focus of activity of the modifying enzymes from one pair of closely spaced groups to another. PMID:7026562

  5. The retrotrapezoid nucleus and breathing.

    Science.gov (United States)

    Guyenet, Patrice G; Stornetta, Ruth L; Abbott, Stephen B G; Depuy, Seth D; Kanbar, Roy

    2012-01-01

    The retrotrapezoid nucleus (RTN) is located in the rostral medulla oblongata close to the ventral surface and consists of a bilateral cluster of glutamatergic neurons that are non-aminergic and express homeodomain transcription factor Phox2b throughout life. These neurons respond vigorously to increases in local pCO(2) via cell-autonomous and paracrine (glial) mechanisms and receive additional chemosensory information from the carotid bodies. RTN neurons exclusively innervate the regions of the brainstem that contain the respiratory pattern generator (RPG). Lesion or inhibition of RTN neurons largely attenuates the respiratory chemoreflex of adult rats whereas their activation increases respiratory rate, inspiratory amplitude and active expiration. Phox2b mutations that cause congenital central hypoventilation syndrome in humans prevent the development of RTN neurons in mice. Selective deletion of the RTN Phox2b-VGLUT2 neurons by genetic means in mice eliminates the respiratory chemoreflex in neonates.In short, RTN Phox2b-VGLUT2 neurons are a major nodal point of the CNS network that regulates pCO(2) via breathing and these cells are probable central chemoreceptors. PMID:23080151

  6. ANTIEMETICS: A REVIEW

    Directory of Open Access Journals (Sweden)

    Amit Kumar* 1 and Anoop Kumar 2

    2013-01-01

    Full Text Available The act of emesis is controlled by the vomiting centre in the medulla, which integrates afferent input from the vestibular system, the chemoreceptor trigger zone (CTZ, the cortex and the gut. Nausea and vomiting induced by several cancer chemotherapy agents is often the most distressing side effect of treatment. The mechanism of action of antiemetic is related to blockage of various type of receptor located in various region of various organ of the body parts. Various drugs are classified under antiemetic like Ondansetron, Granisetron & Metochlopramide etc. A critical review of the studies of aprepitant (a new NK1 receptor antagonist and of palonosetron (a 5-HT3 receptor antagonist with a longer half-life presented in this article. Aprepitant combined with dexamethasone and a 5-HT3 antagonist significantly increase the control of acute emesis with respect to dexamethasone. Palonosetron showed superior or similar efficacy to Ondansetron and dolasetron in patients submitted to moderately emetogenic chemotherapy Certain side effects arise due to excessive use of antiemetic like twitching, flushing of skin, headaches, tiredness, indigestion etc.

  7. Fetal breathing movements and changes at birth.

    Science.gov (United States)

    Koos, Brian J; Rajaee, Arezoo

    2014-01-01

    The fetus, which develops within a fluid-filled amniotic sac, relies on the placenta for respiratory gas exchange rather than the lungs. While not involved in fetal oxygenation, fetal breathing movements (FBM) nevertheless have an important role in lung growth and in development of respiratory muscles and neural regulation. FBM are regulated differently in many respects than postnatal respiration, which results from the unique intrauterine environment. Prominent distinctions of FBM include its episodic nature and apnea-sensitivity to hypoxia. The latter characteristic is the basis for using FBM in the assessment of fetuses at risk for hypoxic injury. At birth, the transition to continuous postnatal respiration involves a fall in temperature, gaseous distention of the lungs, activation of the Hering-Breuer reflexes, and functional connectivity of afferent O2 chemoreceptor activity with respiratory motoneurons and arousal centers. Importantly, exposure to drugs or adverse conditions in utero not only can change patterns of FBM but also can lead to epigenetic dysregulation in postnatal respiration. Such changes, can blunt respiratory and arousal defenses against hypoxic challenges in sleep. Thus, fetal hypoxia and/or drug exposure may in later life dispose sleeping infants, children, and adults to hypertension, diabetes mellitus, brain injury, and sudden death. PMID:25015803

  8. EFFECTS OF DIFFERENT PHASES OF MENSTRUAL CYCLE ON RESPIRATION

    Directory of Open Access Journals (Sweden)

    Hemalatha

    2014-11-01

    Full Text Available BACKGROUND: Menstrual cycle is an integral part of life in women. The characteristic rhythmic changes in the rate of secretion of ovarian hormones produce physiological changes in different organ systems, in addition to changes in the reproductive system. AIM: The present study is done to elucidate a possible correlative changes in respiration during the different (menstrual, luteal and follicular phases of menstrual cycle in healthy young girls. MATERIAL AND METHODS: Volume and rate of resting ventilation were measured serially in 40 healthy female student’s volunteers, during menstrual, follicular and luteal phases of menstrual cycle. STATISTICAL ANALYSES: ANOVA, ‘T’ test and ‘P’ value are applied to find out statistical significance and conclusions are drawn based on this statistical treatment. RESULTS: Respiratory Rate was significantly higher (Pchemoreceptors or by both, thus suggesting a possible beneficial role of progesterone in the management of respiratory illnesses.

  9. Controlled breathing protocols probe human autonomic cardiovascular rhythms

    Science.gov (United States)

    Cooke, W. H.; Cox, J. F.; Diedrich, A. M.; Taylor, J. A.; Beightol, L. A.; Ames, J. E. 4th; Hoag, J. B.; Seidel, H.; Eckberg, D. L.

    1998-01-01

    The purpose of this study was to determine how breathing protocols requiring varying degrees of control affect cardiovascular dynamics. We measured inspiratory volume, end-tidal CO2, R-R interval, and arterial pressure spectral power in 10 volunteers who followed the following 5 breathing protocols: 1) uncontrolled breathing for 5 min; 2) stepwise frequency breathing (at 0.3, 0.25, 0.2, 0.15, 0.1, and 0.05 Hz for 2 min each); 3) stepwise frequency breathing as above, but with prescribed tidal volumes; 4) random-frequency breathing (approximately 0.5-0.05 Hz) for 6 min; and 5) fixed-frequency breathing (0.25 Hz) for 5 min. During stepwise breathing, R-R interval and arterial pressure spectral power increased as breathing frequency decreased. Control of inspired volume reduced R-R interval spectral power during 0.1 Hz breathing (P respiration and R-R intervals and systolic pressure and R-R intervals. Random- and fixed-frequency breathing reduced end-tidal CO2 modestly (P tidal volume control attenuates low-frequency R-R interval oscillations and that fixed- and random-rate breathing may decrease CO2 chemoreceptor stimulation. We conclude that autonomic rhythms measured during different breathing protocols have much in common but that a stepwise protocol without stringent control of inspired volume may allow for the most efficient assessment of short-term respiratory-mediated autonomic oscillations.

  10. Central neural control of the cardiovascular system: current perspectives.

    Science.gov (United States)

    Dampney, Roger A L

    2016-09-01

    This brief review, which is based on a lecture presented at the American Physiological Society Teaching Refresher Course on the Brain and Systems Control as part of the Experimental Biology meeting in 2015, aims to summarize current concepts of the principal mechanisms in the brain that regulate the autonomic outflow to the cardiovascular system. Such cardiovascular regulatory mechanisms do not operate in isolation but are closely coordinated with respiratory and other regulatory mechanisms to maintain homeostasis. The brain regulates the cardiovascular system by two general means: 1) feedforward regulation, often referred to as "central command," and 2) feedback or reflex regulation. In most situations (e.g., during exercise, defensive behavior, sleep, etc.), both of these general mechanisms contribute to overall cardiovascular homeostasis. The review first describes the mechanisms and central circuitry subserving the baroreceptor, chemoreceptor, and other reflexes that work together to regulate an appropriate level of blood pressure and blood oxygenation and then considers the brain mechanisms that defend the body against more complex environmental challenges, using dehydration and cold and heat stress as examples. The last section of the review considers the central mechanisms regulating cardiovascular function associated with different behaviors, with a specific focus on defensive behavior and exercise. PMID:27445275

  11. GPCRs Direct Germline Development and Somatic Gonad Function in Planarians.

    Science.gov (United States)

    Saberi, Amir; Jamal, Ayana; Beets, Isabel; Schoofs, Liliane; Newmark, Phillip A

    2016-05-01

    Planarians display remarkable plasticity in maintenance of their germline, with the ability to develop or dismantle reproductive tissues in response to systemic and environmental cues. Here, we investigated the role of G protein-coupled receptors (GPCRs) in this dynamic germline regulation. By genome-enabled receptor mining, we identified 566 putative planarian GPCRs and classified them into conserved and phylum-specific subfamilies. We performed a functional screen to identify NPYR-1 as the cognate receptor for NPY-8, a neuropeptide required for sexual maturation and germ cell differentiation. Similar to NPY-8, knockdown of this receptor results in loss of differentiated germ cells and sexual maturity. NPYR-1 is expressed in neuroendocrine cells of the central nervous system and can be activated specifically by NPY-8 in cell-based assays. Additionally, we screened the complement of GPCRs with expression enriched in sexually reproducing planarians, and identified an orphan chemoreceptor family member, ophis, that controls differentiation of germline stem cells (GSCs). ophis is expressed in somatic cells of male and female gonads, as well as in accessory reproductive tissues. We have previously shown that somatic gonadal cells are required for male GSC specification and maintenance in planarians. However, ophis is not essential for GSC specification or maintenance and, therefore, defines a secondary role for planarian gonadal niche cells in promoting GSC differentiation. Our studies uncover the complement of planarian GPCRs and reveal previously unappreciated roles for these receptors in systemic and local (i.e., niche) regulation of germ cell development. PMID:27163480

  12. CHARACTERIZATION OF THE OLFACTORY RECEPTORS EXPRESSED IN HUMAN SPERMATOZOA

    Directory of Open Access Journals (Sweden)

    Caroline eFlegel

    2016-01-01

    Full Text Available The detection of external cues is fundamental for human spermatozoa to locate the oocyte in the female reproductive tract. This task requires a specific chemoreceptor repertoire that is expressed on the surface of human spermatozoa, which is not fully identified to date. Olfactory receptors (ORs are candidate molecules and have been attributed to be involved in sperm chemotaxis and chemokinesis, indicating an important role in mammalian spermatozoa. An increasing importance has been suggested for spermatozoal RNA, which led us to investigate the expression of all 387 OR genes. This study provides the first comprehensive analysis of OR transcripts in human spermatozoa of several individuals by RNA-Seq. We detected 91 different transcripts in the spermatozoa samples that could be aligned to annotated OR genes. Using stranded mRNA-Seq, we detected a class of these putative OR transcripts in an antisense orientation, indicating a different function, rather than coding for a functional OR protein. Nevertheless, we were able to detect OR proteins in various compartments of human spermatozoa, indicating distinct functions in human sperm. A panel of various OR ligands induced Ca2+ signals in human spermatozoa, which could be inhibited by mibefradil. This study indicated that a variety of ORs are expressed at the mRNA and protein level in human spermatozoa and demonstrates that ORs are involved in the physiological processes.

  13. The Spiny Rat Mite Echinolaelaps echidninus (Berlese, 1887 (Dermanyssoidea: Laelapidae: Redescription of the Female with Emphasis on its Gnathosoma, Sense Organs, Peritreme and Pulvilli

    Directory of Open Access Journals (Sweden)

    Ashraf Ahmed Montasser

    2006-01-01

    Full Text Available The present Scanning Electron Microscopic (SEM study includes redescription of female Echinolaelaps echidninus with emphasis on its gnathosoma, sense organs, peritreme and pulvilli which were rarely described in superfamily Dermanyssoidea. Chaetotaxy of dorsal shield revealed 40 pairs of setae, 22 on prosoma and 18 on opisthosoma. Epigynial plate carried 5 pairs of setae. Gnathosoma consisted of long basis capituli carrying median hypostome and 2 lateral pedipalps. Hypostome had dorsal labrum covered with finger-like processes, 2 lateral 3-segmented chelicerae and ventral labium carrying 4 lobulated plates. Function of labrum processes might be chemosensory while labium lobules might be mechanical, preventing solid material from entering the oral cavity. Palpal and foreleg tarsal organs comprised 10 and 16 sensillae, respectively. Sensillae of palpal organ were mostly chemoreceptors while those of tarsal organ were probably mechanoreceptors. Peritremal pit contained 4 rows of hand-like papillae and 5 concentric rows of minute papillae. Each pulvillus terminated with 2 medioventral claws. Pulvillus I had terminal integumental folds while each pulvillus II-IV had 2 lateral comb-like plates. Each plate carried 8-10 processes.

  14. A would-be nervous system made from a slime mold.

    Science.gov (United States)

    Adamatzky, Andrew

    2015-01-01

    The slime mold Physarum polycephalum is a huge single cell that has proved to be a fruitful material for designing novel computing architectures. The slime mold is capable of sensing tactile, chemical, and optical stimuli and converting them to characteristic patterns of its electrical potential oscillations. The electrical responses to stimuli may propagate along protoplasmic tubes for distances exceeding tens of centimeters, as impulses in neural pathways do. A slime mold makes decisions about its propagation direction based on information fusion from thousands of spatially extended protoplasmic loci, similarly to a neuron collecting information from its dendritic tree. The analogy is distant yet inspiring. We speculate on whether alternative-would-be-nervous systems can be developed and practically implemented from the slime mold. We uncover analogies between the slime mold and neurons, and demonstrate that the slime mold can play the roles of primitive mechanoreceptors, photoreceptors, and chemoreceptors; we also show how the Physarum neural pathways develop. The results constituted the first step towards experimental laboratory studies of nervous system implementation in slime molds. PMID:25514435

  15. Enhanced carotid body chemosensory activity and the cardiovascular alterations induced by intermittent hypoxia

    Directory of Open Access Journals (Sweden)

    Rodrigo eIturriaga

    2014-12-01

    Full Text Available The carotid body (CB plays a main role in the maintenance of the oxygen homeostasis. The hypoxic stimulation of the CB increases the chemosensory discharge, which in turn elicits reflex sympathetic, cardiovascular and ventilatory adjustments. An exacerbate carotid chemosensory activity has been associated with human sympathetic-mediated diseases such as hypertension, insulin resistance, heart failure and obstructive sleep apnea (OSA. Indeed, the CB chemosensory discharge becomes tonically hypereactive in experimental models of OSA and heart failure. Chronic intermittent hypoxia (CIH, a main feature of OSA, enhances CB chemosensory baseline discharges in normoxia and in response to hypoxia, inducing sympathetic overactivity and hypertension. Oxidative stress, increased levels of ET-1, Angiotensin II and pro-inflammatory cytokines, along with a reduced production of NO in the CB, have been associated with the enhanced carotid chemosensory activity. In this review, we will discuss new evidence supporting a main role for the CB chemoreceptor in the autonomic and cardiorespiratory alterations induced by intermittent hypoxia, as well as the molecular mechanisms involved in the CB chemosensory potentiation.

  16. Ventilatory response to high inspired carbon dioxide concentrations in anesthetized dogs

    Directory of Open Access Journals (Sweden)

    Jack A Loeppky

    2011-01-01

    Full Text Available Background : The ventilation ( response to inspired CO 2 has been extensively studied, but rarely with concentrations >10%. Aims : These experiments were performed to determine whether would increase correspondingly to higher concentrations and according to conventional chemoreceptor time delays. Materials and Methods : We exposed anesthetized dogs acutely, with and without vagotomy and electrical stimulation of the right vagus, to 20-100% CO 2 -balance O 2 .and to 0 and 10% O 2 -balance N 2 . Results : The time delays decreased and response magnitude increased with increasing concentrations (p<0.01, but at higher concentrations the time delays were shorter than expected, i.e., 0.5 s to double at 100% CO 2 , with the response to 0% O 2 being ~3 s slower. Right vagotomy significantly reduced baseline breathing frequency (fR, increased tidal volume (VT and increased the time delay by ~3 s. Bilateral vagotomy further reduced baseline fR and , and reduced the response to CO 2 and increased the time delay by ~12 s. Electro-stimulation of the peripheral right vagus while inspiring CO 2 caused a 13 s asystole and further reduced and delayed the response, especially after bilateral vagotomy, shifting the mode from VT to fR. Conclusions : Results indicate that airway or lung receptors responded to the rapid increase in lung H + and that vagal afferents and unimpaired circulation seem necessary for the initial rapid response to high CO 2 concentrations by receptors upstream from the aortic bodies.

  17. A preliminary anatomical study on carotid body of Makouei sheep

    Directory of Open Access Journals (Sweden)

    Gholamreza Najafi

    2013-06-01

    Full Text Available The carotid is a small mass of chemoreceptor's and sustentacular cells that detects changes in the composition of the arterial blood. The aim of the present study was to identify the size, color, location, blood and nerve supply of the carotid body in Makouei sheep. Fourteen heads of sheep from both sexes were collected from Urmia public slaughter-house. The exact situation and nerve supply of the carotid body was determined. Before dissection, blue latex was injected into right and left common carotid arteries. All the branches of the common carotid artery and the branch supplying carotid body were investigated. This study showed that, carotid body in sheep has been situated around the muscular branch of the occipital artery. The mean weight, width and length, thickness of carotid body were 0.01 g, 0.83 mm, 1.07 mm, and 1.06 mm respectively. Blood to the carotid body was supplied by glomic artery which was a branch of occipital artery. It was innervated by herring nerve which was a branch of glossopharyngeal nerve.

  18. Bacterial lifestyle in a deep-sea hydrothermal vent chimney revealed by the genome sequence of the thermophilic bacterium Deferribacter desulfuricans SSM1.

    Science.gov (United States)

    Takaki, Yoshihiro; Shimamura, Shigeru; Nakagawa, Satoshi; Fukuhara, Yasuo; Horikawa, Hiroshi; Ankai, Akiho; Harada, Takeshi; Hosoyama, Akira; Oguchi, Akio; Fukui, Shigehiro; Fujita, Nobuyuki; Takami, Hideto; Takai, Ken

    2010-06-01

    The complete genome sequence of the thermophilic sulphur-reducing bacterium, Deferribacter desulfuricans SMM1, isolated from a hydrothermal vent chimney has been determined. The genome comprises a single circular chromosome of 2,234,389 bp and a megaplasmid of 308,544 bp. Many genes encoded in the genome are most similar to the genes of sulphur- or sulphate-reducing bacterial species within Deltaproteobacteria. The reconstructed central metabolisms showed a heterotrophic lifestyle primarily driven by C1 to C3 organics, e.g. formate, acetate, and pyruvate, and also suggested that the inability of autotrophy via a reductive tricarboxylic acid cycle may be due to the lack of ATP-dependent citrate lyase. In addition, the genome encodes numerous genes for chemoreceptors, chemotaxis-like systems, and signal transduction machineries. These signalling networks may be linked to this bacterium's versatile energy metabolisms and may provide ecophysiological advantages for D. desulfuricans SSM1 thriving in the physically and chemically fluctuating environments near hydrothermal vents. This is the first genome sequence from the phylum Deferribacteres. PMID:20189949

  19. Nuclear molecular imaging of paragangliomas; Imagerie moleculaire nucleaire des paragangliomes

    Energy Technology Data Exchange (ETDEWEB)

    Taieb, D.; Tessonnier, L.; Mundler, O. [Service central de biophysique et de medecine nucleaire, CHU de la Timone, 13 - Marseille (France)

    2010-08-15

    Paragangliomas (PGL) are relatively rare neural crest tumors originating in the adrenal medulla (usually called pheochromocytoma), chemoreceptors (i.e., carotid and aortic bodies) or autonomic ganglia. These tumors are highly vascular, usually benign and slow-growing. PGL may occur as sporadic or familial entities, the latter mostly in association with germline mutations of the succinate dehydrogenase (SDH) B, SDHC, SDHD, SDH5, von Hippel-Lindau (VHL), ret proto-oncogene (RET), neurofibromatosis 1 (NF1) (von Recklinghausen's disease), prolyl hydroxylase domain protein 2 (PHD2) genes and TMEM127. Molecular nuclear imaging has a central role in characterization of PGL and include: somatostatin receptor imaging ({sup 111}In, {sup 68}Ga), MIBG scintigraphy ({sup 131}I, {sup 123}I), {sup 18}F-dihydroxy-phenylalanine ({sup 18}F-DOPA) positron emission tomography (PET), and {sup 18}F-deoxyglucose ({sup 18}F-FDG) PET. The choice of the tracer is not yet fully established but the work-up of familial forms often require the combination of multiple approaches. (authors)

  20. P2X receptors.

    Science.gov (United States)

    North, R Alan

    2016-08-01

    Extracellular adenosine 5'-triphosphate (ATP) activates cell surface P2X and P2Y receptors. P2X receptors are membrane ion channels preferably permeable to sodium, potassium and calcium that open within milliseconds of the binding of ATP. In molecular architecture, they form a unique structural family. The receptor is a trimer, the binding of ATP between subunits causes them to flex together within the ectodomain and separate in the membrane-spanning region so as to open a central channel. P2X receptors have a widespread tissue distribution. On some smooth muscle cells, P2X receptors mediate the fast excitatory junction potential that leads to depolarization and contraction. In the central nervous system, activation of P2X receptors allows calcium to enter neurons and this can evoke slower neuromodulatory responses such as the trafficking of receptors for the neurotransmitter glutamate. In primary afferent nerves, P2X receptors are critical for the initiation of action potentials when they respond to ATP released from sensory cells such as taste buds, chemoreceptors or urothelium. In immune cells, activation of P2X receptors triggers the release of pro-inflammatory cytokines such as interleukin 1β. The development of selective blockers of different P2X receptors has led to clinical trials of their effectiveness in the management of cough, pain, inflammation and certain neurodegenerative diseases.This article is part of the themed issue 'Evolution brings Ca(2+) and ATP together to control life and death'. PMID:27377721

  1. Sensing and surviving hypoxia in vertebrates.

    Science.gov (United States)

    Jonz, Michael G; Buck, Leslie T; Perry, Steve F; Schwerte, Thorsten; Zaccone, Giacomo

    2016-02-01

    Surviving hypoxia is one of the most critical challenges faced by vertebrates. Most species have adapted to changing levels of oxygen in their environment with specialized organs that sense hypoxia, while only few have been uniquely adapted to survive prolonged periods of anoxia. The goal of this review is to present the most recent research on oxygen sensing, adaptation to hypoxia, and mechanisms of anoxia tolerance in nonmammalian vertebrates. We discuss the respiratory structures in fish, including the skin, gills, and air-breathing organs, and recent evidence for chemosensory neuroepithelial cells (NECs) in these tissues that initiate reflex responses to hypoxia. The use of the zebrafish as a genetic and developmental model has allowed observation of the ontogenesis of respiratory and chemosensory systems, demonstration of a putative intracellular O2 sensor in chemoreceptors that may initiate transduction of the hypoxia signal, and investigation into the effects of extreme hypoxia on cardiorespiratory development. Other organisms, such as goldfish and freshwater turtles, display a high degree of anoxia tolerance, and these models are revealing important adaptations at the cellular level, such as the regulation of glutamatergic and GABAergic neurotransmission in defense of homeostasis in central neurons. PMID:25959851

  2. Time Domains of the Hypoxic Ventilatory Response and Their Molecular Basis.

    Science.gov (United States)

    Pamenter, Mathhew E; Powell, Frank L

    2016-01-01

    Ventilatory responses to hypoxia vary widely depending on the pattern and length of hypoxic exposure. Acute, prolonged, or intermittent hypoxic episodes can increase or decrease breathing for seconds to years, both during the hypoxic stimulus, and also after its removal. These myriad effects are the result of a complicated web of molecular interactions that underlie plasticity in the respiratory control reflex circuits and ultimately control the physiology of breathing in hypoxia. Since the time domains of the physiological hypoxic ventilatory response (HVR) were identified, considerable research effort has gone toward elucidating the underlying molecular mechanisms that mediate these varied responses. This research has begun to describe complicated and plastic interactions in the relay circuits between the peripheral chemoreceptors and the ventilatory control circuits within the central nervous system. Intriguingly, many of these molecular pathways seem to share key components between the different time domains, suggesting that varied physiological HVRs are the result of specific modifications to overlapping pathways. This review highlights what has been discovered regarding the cell and molecular level control of the time domains of the HVR, and highlights key areas where further research is required. Understanding the molecular control of ventilation in hypoxia has important implications for basic physiology and is emerging as an important component of several clinical fields. © 2016 American Physiological Society. Compr Physiol 6:1345-1385, 2016. PMID:27347896

  3. Respiratory modulation of sympathetic nerve activity is enhanced in male rat offspring following uteroplacental insufficiency.

    Science.gov (United States)

    Menuet, C; Wlodek, M E; Fong, A Y; Allen, A M

    2016-06-01

    Sympathetic nerve activity to the cardiovascular system displays prominent respiratory-related modulation which leads to the generation of rhythmic oscillations in blood pressure called Traube-Hering waves. An amplification of this respiratory modulation of sympathetic activity is observed in hypertension of both genetic, the spontaneously hypertensive rat, and induced, chronic intermittent hypoxia or maternal protein restriction during gestation, origin. Male offspring of mothers with uteroplacental insufficiency, induced by bilateral uterine vessel ligation at 18 days of gestation, are also hypertensive in adulthood. In this study we examined whether these male offspring display altered respiratory modulation of sympathetic activity at pre-hypertensive ages compared to controls. Respiratory, cardiovascular and sympathetic parameters were examined using the working heart-brainstem preparation in 35 day old male rats that had reduced birth weight due to uteroplacental insufficiency. Whilst all respiratory parameters were not different between groups, we observed an enhanced respiratory-related burst of thoracic sympathetic nerve activity and amplified Traube-Hering waves in the growth-restricted group. This group also showed an increased sympathetic and bradycardic response to activation of peripheral chemoreceptors. The observations add support to the view that altered respiratory modulation of sympathetic activity represents a common mechanism involved in the development of several forms of hypertension. PMID:26593642

  4. Neural reflex regulation of arterial pressure in pathophysiological conditions: interplay among the baroreflex, the cardiopulmonary reflexes and the chemoreflex

    Directory of Open Access Journals (Sweden)

    E.C. Vasquez

    1997-04-01

    Full Text Available The maintenance of arterial pressure at levels adequate to perfuse the tissues is a basic requirement for the constancy of the internal environment and survival. The objective of the present review was to provide information about the basic reflex mechanisms that are responsible for the moment-to-moment regulation of the cardiovascular system. We demonstrate that this control is largely provided by the action of arterial and non-arterial reflexes that detect and correct changes in arterial pressure (baroreflex, blood volume or chemical composition (mechano- and chemosensitive cardiopulmonary reflexes, and changes in blood-gas composition (chemoreceptor reflex. The importance of the integration of these cardiovascular reflexes is well understood and it is clear that processing mainly occurs in the nucleus tractus solitarii, although the mechanism is poorly understood. There are several indications that the interactions of baroreflex, chemoreflex and Bezold-Jarisch reflex inputs, and the central nervous system control the activity of autonomic preganglionic neurons through parallel afferent and efferent pathways to achieve cardiovascular homeostasis. It is surprising that so little appears in the literature about the integration of these neural reflexes in cardiovascular function. Thus, our purpose was to review the interplay between peripheral neural reflex mechanisms of arterial blood pressure and blood volume regulation in physiological and pathophysiological states. Special emphasis is placed on the experimental model of arterial hypertension induced by N-nitro-L-arginine methyl ester (L-NAME in which the interplay of these three reflexes is demonstrable

  5. Chronic intermittent hypoxia alters ventilatory and metabolic responses to acute hypoxia in rats.

    Science.gov (United States)

    Morgan, Barbara J; Adrian, Russell; Wang, Zun-Yi; Bates, Melissa L; Dopp, John M

    2016-05-15

    We determined the effects of chronic exposure to intermittent hypoxia (CIH) on chemoreflex control of ventilation in conscious animals. Adult male Sprague-Dawley rats were exposed to CIH [nadir oxygen saturation (SpO2), 75%; 15 events/h; 10 h/day] or normoxia (NORM) for 21 days. We assessed the following responses to acute, graded hypoxia before and after exposures: ventilation (V̇e, via barometric plethysmography), V̇o2 and V̇co2 (analysis of expired air), heart rate (HR), and SpO2 (pulse oximetry via neck collar). We quantified hypoxia-induced chemoreceptor sensitivity by calculating the stimulus-response relationship between SpO2 and the ventilatory equivalent for V̇co2 (linear regression). An additional aim was to determine whether CIH causes proliferation of carotid body glomus cells (using bromodeoxyuridine). CIH exposure increased the slope of the V̇e/V̇co2/SpO2 relationship and caused hyperventilation in normoxia. Bromodeoxyuridine staining was comparable in CIH and NORM. Thus our CIH paradigm augmented hypoxic chemosensitivity without causing glomus cell proliferation. PMID:26917692

  6. The Pseudomonas aeruginosa chemotaxis methyltransferase CheR1 impacts on bacterial surface sampling.

    Directory of Open Access Journals (Sweden)

    Juliane Schmidt

    Full Text Available The characterization of factors contributing to the formation and development of surface-associated bacterial communities known as biofilms has become an area of intense interest since biofilms have a major impact on human health, the environment and industry. Various studies have demonstrated that motility, including swimming, swarming and twitching, seems to play an important role in the surface colonization and establishment of structured biofilms. Thereby, the impact of chemotaxis on biofilm formation has been less intensively studied. Pseudomonas aeruginosa has a very complex chemosensory system with two Che systems implicated in flagella-mediated motility. In this study, we demonstrate that the chemotaxis protein CheR1 is a methyltransferase that binds S-adenosylmethionine and transfers a methyl group from this methyl donor to the chemoreceptor PctA, an activity which can be stimulated by the attractant serine but not by glutamine. We furthermore demonstrate that CheR1 does not only play a role in flagella-mediated chemotaxis but that its activity is essential for the formation and maintenance of bacterial biofilm structures. We propose a model in which motility and chemotaxis impact on initial attachment processes, dispersion and reattachment and increase the efficiency and frequency of surface sampling in P. aeruginosa.

  7. Antennal sensilla of the green bottle fly, Lucilia sericata (Meigen) (Diptera: Calliphoridae).

    Science.gov (United States)

    Zhang, D; Liu, X H; Li, X Y; Zhang, M; Li, K

    2013-11-01

    Lucilia sericata (Meigen) is a cosmopolitan synanthropic fly of forensic and medical importance, which can work as a mechanic vector of pathogens or cause myiasis of both human and sheep. As essential olfactory organs, antennae of adult L. sericata were examined with stereoscopic microscope, scanning electron microscope, and laser scanning confocal microscope. On antennal scape and pedicel, both microtirchiae and several bristles are detected, while another two structures, setiferous plaques and pedicellar buttons, are also found on the antennal pedicel. Seven subtypes of antennal sensilla are observed on antennal funiculus including one subtype of trichoid sensilla, two subtypes of basiconic sensilla, two subtypes of coeloconic sensilla, and two subtypes of sensory pits. Size and density of the former four types of sensilla on antennal funiculus are measured. Three distinctive sensillar characters of L. sericata are detected, which may contribute to greater olfactory sensitivity of this species and their wide distribution throughout the world. Unlike the common poreless pedicellar button with mechanoreceptor function, every pedicellar button in L. sericata is perforated by three pores, which might indicate potential chemoreceptor function of this structure. Besides, another unique feature is greater number of setiferous plaques in genus Lucilia than calliphorids of other genera. Expect for the common sensory pits with basiconic or basiconic-like sensilla in them, sensory pits filled with rarely described coeloconic-like sensilla are founded in L. sericata as well. After comparison with previous equivalent findings, the functions of these specific structures are discussed according to the life history of this calliphorid. PMID:23955594

  8. Cellular Architecture of Treponema pallidum: Novel Flagellum, Periplasmic Cone, and Cell Envelope as Revealed by Cryo-Electron Tomography

    Science.gov (United States)

    Liu, Jun; Howell, Jerrilyn K.; Bradley, Sherille D.; Zheng, Yesha; Zhou, Z. Hong; Norris, Steven J.

    2010-01-01

    High resolution cryo-electron tomography (cryo-ET) was utilized to visualize Treponema pallidum, the causative agent of syphilis, at the molecular level. Three-dimensional (3-D) reconstructions from 304 infectious organisms revealed unprecedented cellular structures of this unusual member in the spirochetal family. High resolution cryo-ET reconstructions provided the detailed structures of the cell envelope, which is significantly different from that of gram-negative bacteria. The 4 nm lipid bilayer of both outer and cytoplasmic membranes resolved in 3-D reconstructions, providing an important marker for interpreting membrane-associated structures. Abundant lipoproteins cover the outer leaflet of the cytoplasmic membrane, in contrast to the rare outer membrane proteins visible by scanning probe microscopy. High resolution cryo-ET images also provided the first observation of T. pallidum chemoreceptor arrays, as well as structural details of the periplasmically located, cone-shaped structure at both ends of bacterium. Furthermore, 3-D subvolume averages of the periplasmic flagellar motors and filaments from living organisms revealed the novel flagellar architectures that may facilitate their rotation within the confining periplasmic space. Together, our findings provide the most detailed structural understanding of the periplasmic flagella and the surrounding cell envelope, which enable this enigmatic bacterium to efficiently penetrate tissue and escape host immune responses. PMID:20850455

  9. The monarch butterfly genome yields insights into long-distance migration.

    Science.gov (United States)

    Zhan, Shuai; Merlin, Christine; Boore, Jeffrey L; Reppert, Steven M

    2011-11-23

    We present the draft 273 Mb genome of the migratory monarch butterfly (Danaus plexippus) and a set of 16,866 protein-coding genes. Orthology properties suggest that the Lepidoptera are the fastest evolving insect order yet examined. Compared to the silkmoth Bombyx mori, the monarch genome shares prominent similarity in orthology content, microsynteny, and protein family sizes. The monarch genome reveals a vertebrate-like opsin whose existence in insects is widespread; a full repertoire of molecular components for the monarch circadian clockwork; all members of the juvenile hormone biosynthetic pathway whose regulation shows unexpected sexual dimorphism; additional molecular signatures of oriented flight behavior; microRNAs that are differentially expressed between summer and migratory butterflies; monarch-specific expansions of chemoreceptors potentially important for long-distance migration; and a variant of the sodium/potassium pump that underlies a valuable chemical defense mechanism. The monarch genome enhances our ability to better understand the genetic and molecular basis of long-distance migration. PMID:22118469

  10. Chemotactic response and adaptation dynamics in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Diana Clausznitzer

    2010-05-01

    Full Text Available Adaptation of the chemotaxis sensory pathway of the bacterium Escherichia coli is integral for detecting chemicals over a wide range of background concentrations, ultimately allowing cells to swim towards sources of attractant and away from repellents. Its biochemical mechanism based on methylation and demethylation of chemoreceptors has long been known. Despite the importance of adaptation for cell memory and behavior, the dynamics of adaptation are difficult to reconcile with current models of precise adaptation. Here, we follow time courses of signaling in response to concentration step changes of attractant using in vivo fluorescence resonance energy transfer measurements. Specifically, we use a condensed representation of adaptation time courses for efficient evaluation of different adaptation models. To quantitatively explain the data, we finally develop a dynamic model for signaling and adaptation based on the attractant flow in the experiment, signaling by cooperative receptor complexes, and multiple layers of feedback regulation for adaptation. We experimentally confirm the predicted effects of changing the enzyme-expression level and bypassing the negative feedback for demethylation. Our data analysis suggests significant imprecision in adaptation for large additions. Furthermore, our model predicts highly regulated, ultrafast adaptation in response to removal of attractant, which may be useful for fast reorientation of the cell and noise reduction in adaptation.

  11. The Valsalva manoeuvre: physiology and clinical examples.

    Science.gov (United States)

    Pstras, L; Thomaseth, K; Waniewski, J; Balzani, I; Bellavere, F

    2016-06-01

    The Valsalva manoeuvre (VM), a forced expiratory effort against a closed airway, has a wide range of applications in several medical disciplines, including diagnosing heart problems or autonomic nervous system deficiencies. The changes of the intrathoracic and intra-abdominal pressure associated with the manoeuvre result in a complex cardiovascular response with a concomitant action of several regulatory mechanisms. As the main aim of the reflex mechanisms is to control the arterial blood pressure (BP), their action is based primarily on signals from baroreceptors, although they also reflect the activity of pulmonary stretch receptors and, to a lower degree, chemoreceptors, with different mechanisms acting either in synergism or in antagonism depending on the phase of the manoeuvre. A variety of abnormal responses to the VM can be seen in patients with different conditions. Based on the arterial BP and heart rate changes during and after the manoeuvre several dysfunctions can be hence diagnosed or confirmed. The nature of the cardiovascular response to the manoeuvre depends, however, not only on the shape of the cardiovascular system and the autonomic function of the given patient, but also on a number of technical factors related to the execution of the manoeuvre including the duration and level of strain, the body position or breathing pattern. This review of the literature provides a comprehensive analysis of the physiology and pathophysiology of the VM and an overview of its applications. A number of clinical examples of normal and abnormal haemodynamic response to the manoeuvre have been also provided. PMID:26662857

  12. Evolution of herbivory in Drosophilidae linked to loss of behaviors, antennal responses, odorant receptors, and ancestral diet.

    Science.gov (United States)

    Goldman-Huertas, Benjamin; Mitchell, Robert F; Lapoint, Richard T; Faucher, Cécile P; Hildebrand, John G; Whiteman, Noah K

    2015-03-10

    Herbivory is a key innovation in insects, yet has only evolved in one-third of living orders. The evolution of herbivory likely involves major behavioral changes mediated by remodeling of canonical chemosensory modules. Herbivorous flies in the genus Scaptomyza (Drosophilidae) are compelling species in which to study the genomic architecture linked to the transition to herbivory because they recently evolved from microbe-feeding ancestors and are closely related to Drosophila melanogaster. We found that Scaptomyza flava, a leaf-mining specialist on plants in the family (Brassicaceae), was not attracted to yeast volatiles in a four-field olfactometer assay, whereas D. melanogaster was strongly attracted to these volatiles. Yeast-associated volatiles, especially short-chain aliphatic esters, elicited strong antennal responses in D. melanogaster, but weak antennal responses in electroantennographic recordings from S. flava. We sequenced the genome of S. flava and characterized this species' odorant receptor repertoire. Orthologs of odorant receptors, which detect yeast volatiles in D. melanogaster and mediate critical host-choice behavior, were deleted or pseudogenized in the genome of S. flava. These genes were lost step-wise during the evolution of Scaptomyza. Additionally, Scaptomyza has experienced gene duplication and likely positive selection in paralogs of Or67b in D. melanogaster. Olfactory sensory neurons expressing Or67b are sensitive to green-leaf volatiles. Major trophic shifts in insects are associated with chemoreceptor gene loss as recently evolved ecologies shape sensory repertoires. PMID:25624509

  13. Pulmonary vascular diseases.

    Science.gov (United States)

    Mélot, C; Naeije, R

    2011-04-01

    Diseases of the pulmonary vasculature are a cause of increased pulmonary vascular resistance (PVR) in pulmonary embolism, chronic thromboembolic pulmonary hypertension (CTEPH), and pulmonary arterial hypertension or decreased PVR in pulmonary arteriovenous malformations on hereditary hemorrhagic telangiectasia, portal hypertension, or cavopulmonary anastomosis. All these conditions are associated with a decrease in both arterial PO2 and PCO2. Gas exchange in pulmonary vascular diseases with increased PVR is characterized by a shift of ventilation and perfusion to high ventilation-perfusion ratios, a mild to moderate increase in perfusion to low ventilation-perfusion ratios, and an increased physiologic dead space. Hypoxemia in these patients is essentially explained by altered ventilation-perfusion matching amplified by a decreased mixed venous PO2 caused by a low cardiac output. Hypocapnia is accounted for by hyperventilation, which is essentially related to an increased chemosensitivity. A cardiac shunt on a patent foramen ovale may be a cause of severe hypoxemia in a proportion of patients with pulmonary hypertension and an increase in right atrial pressure. Gas exchange in pulmonary arteriovenous malformations is characterized by variable degree of pulmonary shunting and/or diffusion-perfusion imbalance. Hypocapnia is caused by an increased ventilation in relation to an increased pulmonary blood flow with direct peripheral chemoreceptor stimulation by shunted mixed venous blood flow. PMID:23737196

  14. Gene set of chemosensory receptors in the polyembryonic endoparasitoid Macrocentrus cingulum.

    Science.gov (United States)

    Ahmed, Tofael; Zhang, Tiantao; Wang, Zhenying; He, Kanglai; Bai, Shuxiong

    2016-01-01

    Insects are extremely successful animals whose odor perception is very prominent due to their sophisticated olfactory system. The main chemosensory organ, antennae play a critical role in detecting odor in ambient environment before initiating appropriate behavioral responses. The antennal chemosensory receptor genes families have been suggested to be involved in olfactory signal transduction pathway as a sensory neuron response. The Macrocentrus cingulum is deployed successfully as a biological control agent for corn pest insects from the Lepidopteran genus Ostrinia. In this research, we assembled antennal transcriptomes of M. cingulum by using next generation sequencing to identify the major chemosensory receptors gene families. In total, 112 olfactory receptors candidates (79 odorant receptors, 20 gustatory receptors, and 13 ionotropic receptors) have been identified from the male and female antennal transcriptome. The sequences of all of these transcripts were confirmed by RT-PCR, and direct DNA sequencing. Expression profiles of gustatory receptors in olfactory and non-olfactory tissues were measured by RT-qPCR. The sex-specific and sex-biased chemoreceptors expression patterns suggested that they may have important functions in sense detection which behaviorally relevant to odor molecules. This reported result provides a comprehensive resource of the foundation in semiochemicals driven behaviors at molecular level in polyembryonic endoparasitoid. PMID:27090020

  15. Ultra Morphological Structure of Sensory Sensillae on the Legs and External Genitalia of the Red Palm Weevil Rhynchophorus ferrugineus (Oliv.)

    International Nuclear Information System (INIS)

    The Red Palm Weevil (RPW) is a major pest infesting date trees in the Gulf region. Chemoreceptors play an important role for insects behaviour in detecting their defined host for feeding, egg laying or mating. The present study is aimed to study morphological structure of sensillae on different legs and external genitalia of both sexes. Three kinds of sensillae are found on the different parts of the three pairs of fore, mid and hind legs, these sensillae are identified as ( Trichoid in three types, coeloconic in two types and one type of Basiconic sensillae). Fore legs bear the highest number of different forms of sensillae, males contained realatively greater number than females. Mid femur only in female bears a dense hair of trichoid sensillae, while they are found on fore- mid and hind femur of males, this may be used for differentiating two sexes. Female ovipositor contained trichoid sensilla can be subdivided into three distinct type1,2, and 3 in addition placoid sensillae, it could be identified four types of trichoid sensilla on the male external genitalia and numerous of placoid sensillae.These may be for hygroreception. (author)

  16. Effects of high altitude on sleep and respiratory system and theirs adaptations.

    Science.gov (United States)

    San, Turhan; Polat, Senol; Cingi, Cemal; Eskiizmir, Gorkem; Oghan, Fatih; Cakir, Burak

    2013-01-01

    High-altitude (HA) environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes because of the change in barometric pressure which causes decrease in the amount of oxygen leading to hypobaric hypoxia. Sustained exposure to hypoxia has adverse effects on body weight, muscle structure and exercise capacity, mental functioning, and sleep quality. The most important step of acclimatization is the hyperventilation which is achieved by hypoxic ventilatory response of the peripheral chemoreceptors. Hyperventilation results in increase in arterial carbon-dioxide concentration. Altitude also affects sleep and cardiac output, which is the other determinant of oxygen delivery. Upon initial exposure to HA, the resting pulse rate increases rapidly, but with acclimatization, heart rate and cardiac output tend to fall. Another important component that leads to decrease in cardiac output is the reduction in the stroke volume with acclimatization. During sleep at HA, the levels of CO2 in the blood can drop very low and this can switch off the drive to breathe. Only after the body senses a further drop in O2 levels breathing is started again. Periodic breathing is thought to result from instability in the control system through the hypoxic drive or the response to CO2. PMID:23690739

  17. Tarantulas do not shoot silk from their legs: experimental evidence in four species of New World tarantulas.

    Science.gov (United States)

    Pérez-Miles, Fernando; Ortíz-Villatoro, David

    2012-05-15

    Theraphosid tarantulas, like all other spiders, secrete silk from spigots on the abdominal spinnerets. A few years ago, it was proposed that the large tarantula Aphonopelma seemanni could extrude silk from specialized spigots on the tarsi to help adhesion to vertical surfaces. This suggestion was later questioned because silk was not observed after the spinnerets had been sealed. Recently, experiments with the tarantula Grammostola rosea again suggested tarsal silk secretion. All observations of the supposed tarsal silk were made in spiders with functional spinnerets, thus contamination with silk coming from the spinnerets could not be excluded. Recent morphological arguments also questioned putative tarsal spigots and proposed that they are actually contact chemoreceptors. We here test the supposed tarsal silk secretion in Aphonopelma seemanni, Avicularia avicularia, Brachypelma vagans and Grammostola mollicoma using similar experimental conditions as the previous authors, but with sealed spinnerets. Our results clearly demonstrate that when spinnerets are sealed, tarantulas do not show any tarsal silk secretion. We reinterpret those putative tarsal spigots and discuss possible evolutionary implications of these findings. PMID:22539742

  18. ULTRASTRUCURAL STUDY OF BEE LOUSE VARROA DESTRUCTOR ANDERSON & TRUEMAN 2000 (ACARI: VARROIDAE) WITH RESISTANCE MODELS FROM APIS MELLIFERA L.

    Science.gov (United States)

    Ammar, Khalaf Nour Abd El-Wahed

    2015-08-01

    The ectoparasitic mite Varroa destructor is the most dangerous pest of honeybee Egyptian race Apis mellifera L., as it causes many losses in apiculture worldwide. Adult female mites are flattened with a dome-shaped dorsal shield. The present SEM study revealed that the flat ventral surface is composed of series of plates. There are 5 rows of small, chemoreceptor papillae posterior to the genito-ventro anal shield, and a unique respiratory structure (peritreme) is located laterally above Coxa III. Peritreme is a chitinized elongated area surrounding stigma opening, provided by a lid that looks like a rose with a curly thick inner membrane which has numerous teeth-like projections. Mite' legs appeared to be modified for parasitism and each is tipped by one distal empodium. The pretarsus of the first pair of legs becomes a concave sucker and the pretarsus of the 3 pairs of the posterior legs consists of membranous amblacral pad (the caruncle). The mouthparts appeared well modified for its diet on bee hernolymph with its' powerful pedipalp for host attachment. High magnification revealed different types of setae distributed on the body, the mechano-receptor pedipalp short. and long anal setae and dorsal shield sensory simple setae. PMID:26485856

  19. Effects of High Altitude on Sleep and Respiratory System and Theirs Adaptations

    Directory of Open Access Journals (Sweden)

    Turhan San

    2013-01-01

    Full Text Available High-altitude (HA environments have adverse effects on the normal functioning body of people accustomed to living at low altitudes because of the change in barometric pressure which causes decrease in the amount of oxygen leading to hypobaric hypoxia. Sustained exposure to hypoxia has adverse effects on body weight, muscle structure and exercise capacity, mental functioning, and sleep quality. The most important step of acclimatization is the hyperventilation which is achieved by hypoxic ventilatory response of the peripheral chemoreceptors. Hyperventilation results in increase in arterial carbondioxide concentration. Altitude also affects sleep and cardiac output, which is the other determinant of oxygen delivery. Upon initial exposure to HA, the resting pulse rate increases rapidly, but with acclimatization, heart rate and cardiac output tend to fall. Another important component that leads to decrease in cardiac output is the reduction in the stroke volume with acclimatization. During sleep at HA, the levels of CO2 in the blood can drop very low and this can switch off the drive to breathe. Only after the body senses a further drop in O2 levels breathing is started again. Periodic breathing is thought to result from instability in the control system through the hypoxic drive or the response to CO2.

  20. Radiation-induced emesis in cats prevented by 24-hour prior exposure but not by ablation of the area postrema

    International Nuclear Information System (INIS)

    The acute emetic response induced by whole body exposure to cobalt radiation was quantified in cats at doses ranging from 1500 to 9000 rad (100 rad/min). Emesis occurred in a dose-related manner with a maximum incidence of 94% at 4500 rad (11 of 12 cats, mean latency of 98 min). At 6000 rad emesis occurred in 7 of 10 cats (mean latency of 69 min); however, a second exposure to this dose on the following day failed to induce vomiting in all of 5 cats (difference between groups significant at p = .01). After chronic ablation of the area postrema (chemoreceptor trigger zone for vomiting), 4 of 5 cats vomited in response to 4500 rad with a mean latency of 48 min. As was the case with the normal cats, all the postrema-ablated animals failed to vomit in response to a repeated dose of radiation delivered on the next day. The suppression of emesis observed on the second exposure was radiation-specific because 11 of 12 normal cats vomited appropriately in response to xylazine (0.6 mg/kg, im) during the period of refractoriness to radiation

  1. Respiratory-related hypoglossal nerve activity: influence of anesthetics.

    Science.gov (United States)

    Hwang, J C; St John, W M; Bartlett, D

    1983-09-01

    In decerebrate, vagotomized, paralyzed, and ventilated cats, phrenic and respiratory-related hypoglossal discharges were evident at normocapnic normoxia or hyperoxia. Both increased progressively in hypercapnia or hypoxia. With increasing drive, onset of inspiratory hypoglossal activity began earlier relative to phrenic onset; an early expiratory hypoglossal burst was also observed. Following subanesthetic doses of chloralose, halothane, ketamine, or pentobarbital, hypoglossal activity was depressed much more than phrenic discharge. In moderate hypercapnia or hypoxia, phrenic activity increased more than hypoglossal, whereas, at high drive, the latter rose more sharply in some cats. Electromyograms of the diaphragm and genioglossus were recorded in intact awake cats to determine if their responses and those of decerebrates are comparable. Respiratory-related genioglossal discharge was evident in normocapnia. We conclude that anesthesia suppresses hypoglossal motor activities much more than those of the bulbospinal-phrenic system. Data for decerebrate cats and unanesthetized cats or humans provide no evidence of a differential distribution of chemoreceptor afferents on hypoglossal and bulbospinal-phrenic neurons, as suggested by results in anesthetized animals. PMID:6629915

  2. Cross-modal tactile-taste interactions in food evaluations.

    Science.gov (United States)

    Slocombe, B G; Carmichael, D A; Simner, J

    2016-07-29

    Detecting the taste components within a flavoured substance relies on exposing chemoreceptors within the mouth to the chemical components of ingested food. In our paper, we show that the evaluation of taste components can also be influenced by the tactile quality of the food. We first discuss how multisensory factors might influence taste, flavour and smell for both typical and atypical (synaesthetic) populations and we then present two empirical studies showing tactile-taste interactions in the general population. We asked a group of non-synaesthetic adults to evaluate the taste components of flavoured food substances, whilst we presented simultaneous cross-sensory visuo-tactile cues within the eating environment. Specifically, we presented foodstuffs between subjects that were otherwise identical but had a rough versus smooth surface, or were served on a rough versus smooth serving-plate. We found no effect of the serving-plate, but we found the rough/smoothness of the foodstuff itself significantly influenced perception: food was rated as significantly more sour if it had a rough (versus smooth) surface. In modifying taste perception via ostensibly unrelated dimensions, we demonstrate that the detection of tastes within flavours may be influenced by higher level cross-sensory cues. Finally, we suggest that the direction of our cross-sensory associations may speak to the types of hedonic mapping found both in normal multisensory integration, and in the unusual condition of synaesthesia. PMID:26169315

  3. Carotid body chemoreflex: a driver of autonomic abnormalities in sleep apnoea.

    Science.gov (United States)

    Prabhakar, Nanduri R

    2016-08-01

    What is the topic of this review? This article presents emerging evidence for heightened carotid body chemoreflex activity as a major driver of sympathetic activation and hypertension in sleep apnoea patients. What advances does it heighlight? This article discusses the recent advances on cellular, molecular and epigenetic mechanisms underlying the exaggerated chemoreflex in experimental models of sleep apnoea. The carotid bodies are the principal peripheral chemoreceptors for detecting changes in arterial blood oxygen concentration, and the resulting chemoreflex is a potent regulator of the sympathetic tone, blood pressure and breathing. Sleep apnoea is a disease of the respiratory system that affects several million adult humans. Apnoeas occur during sleep, often as a result of obstruction of the upper airway (obstructive sleep apnoea) or because of defective respiratory rhythm generation by the CNS (central sleep apnoea). Patients with sleep apnoea exhibit several co-morbidities, with the most notable among them being heightened sympathetic nerve activity and hypertension. Emerging evidence suggests that intermittent hypoxia resulting from periodic apnoea stimulates the carotid body, and the ensuing chemoreflex mediates the increased sympathetic tone and hypertension in sleep apnoea patients. Rodent models of intermittent hypoxia that simulate the O2 saturation profiles encountered during sleep apnoea have provided important insights into the cellular and molecular mechanisms underlying the heightened carotid body chemoreflex. This article describes how intermittent hypoxia affects the carotid body function and discusses the cellular, molecular and epigenetic mechanisms underlying the exaggerated chemoreflex. PMID:27474260

  4. Directed evolution of a bacterial sensor and its applications

    Science.gov (United States)

    Derr, Paige

    The methyl-accepting chemotaxis proteins are a family of receptors in bacteria that mediate chemotaxis to diverse signals. To explore the plasticity of these proteins, we have developed a simple method for selecting cells that swim towards or away from target compounds. The procedure is based on establishing a diffusive gradient in semi-soft agar plates and does not require that the attractant be metabolized or degraded. We have applied this method to select for variants of the Escherichia coli aspartate receptor, Tar, that have a new or improved response to various chemicals such as amino acids and environmental toxins. We found that Tar can be readily mutated to respond to new chemical signals. We also present potential applications of this selection such as the development of biosensors or novel enzyme activity. The new tar alleles and the techniques described here provide a new approach for exploring the relationship between ligand binding and signal transduction by chemoreceptors and for engineering new receptors for applications in biotechnology.

  5. Cxs and Panx- hemichannels in peripheral and central chemosensing in mammals.

    Directory of Open Access Journals (Sweden)

    Edison Pablo Reyes

    2014-05-01

    Full Text Available Connexins (Cxs and Pannexins (Panx form hemichannels at the plasma membrane of animals. Despite their low open probability under physiological conditions, these hemichannels release signaling molecules (i.e. ATP, Glutamate, PGE2 to the extracellular space, thus subserving in several important physiological processes.Oxygen and CO2 sensing are fundamental to the normal functioning of vertebrate organisms. Fluctuations in blood PO2, PCO2 and pH are sensed at the carotid bifurcations of adult mammals by glomus cells of the carotid bodies. Likewise, changes in pH and/or PCO2 of cerebrospinal fluid are sensed by central chemoreceptors, a group of specialized neurones distributed in the ventrolateral medulla, raphe nuclei, and some other brainstem areas.After many years of research, the molecular mechanisms involved in chemosensing process are not completely understood. This manuscript will review data regarding relationships between chemosensitive cells and the expression of channels formed by Cxs and Panx, with special emphasis in hemichannels.

  6. Formulation development and evaluation of mouth dissolving film of domperidone

    Directory of Open Access Journals (Sweden)

    Pratikkumar Joshi

    2012-01-01

    Full Text Available The present investigation was undertaken with the objective of formulating mouth dissolving film(s of the antiemetic drug Domperidone to enhance the convenience and compliance by the elderly and pediatric patients. Domperidone is a drug of choice in case of nausea and vomiting produced by chemotherapy, migraine headaches, food poisoning and viral infections. It causes dopamine (D2 and D3 receptor blockage both at the chemoreceptor trigger zone and at the gastric level. It shows high first pass metabolism which results in poor bioavailability (10-15%. In view of high first pass metabolism and short plasma half-life it is an ideal candidate for rapid release drug delivery system. The solid dispersions of Domperidone were prepared with the use β-cyclodextrin in various ratios (1:1, 1:2, 1:3 and solubility study was performed to determine the ratio in which solubility of Domperidone was highest (1:3. The selected solid dispersions were then utilized for the preparation of film by solvent casting method utilizing HPMC E15 as a film forming agent and PEG-400 as plasticizer. Five formulae were prepared and were evaluated for their in vitro dissolution characteristics, in vitro disintegration time, and their physico-mechanical properties. The promising film (F1 showed the greatest drug dissolution (more than 75% within 15 min, satisfactory in vitro disintegration time (45 sec and physico-mechanical properties that are suitable for mouth dissolving films.

  7. Formulation development and evaluation of mouth dissolving film of domperidone.

    Science.gov (United States)

    Joshi, Pratikkumar; Patel, Harsha; Patel, Vishnu; Panchal, Rushi

    2012-03-01

    The present investigation was undertaken with the objective of formulating mouth dissolving film(s) of the antiemetic drug Domperidone to enhance the convenience and compliance by the elderly and pediatric patients. Domperidone is a drug of choice in case of nausea and vomiting produced by chemotherapy, migraine headaches, food poisoning and viral infections. It causes dopamine (D2 and D3) receptor blockage both at the chemoreceptor trigger zone and at the gastric level. It shows high first pass metabolism which results in poor bioavailability (10-15%). In view of high first pass metabolism and short plasma half-life it is an ideal candidate for rapid release drug delivery system. The solid dispersions of Domperidone were prepared with the use β-cyclodextrin in various ratios (1:1, 1:2, 1:3) and solubility study was performed to determine the ratio in which solubility of Domperidone was highest (1:3). The selected solid dispersions were then utilized for the preparation of film by solvent casting method utilizing HPMC E15 as a film forming agent and PEG-400 as plasticizer. Five formulae were prepared and were evaluated for their in vitro dissolution characteristics, in vitro disintegration time, and their physico-mechanical properties. The promising film (F1) showed the greatest drug dissolution (more than 75% within 15 min), satisfactory in vitro disintegration time (45 sec) and physico-mechanical properties that are suitable for mouth dissolving films. PMID:23066181

  8. Immunohistochemical localization of dopamine D2 receptor in the rat carotid body.

    Science.gov (United States)

    Wakai, Jun; Takayama, Anna; Yokoyama, Takuya; Nakamuta, Nobuaki; Kusakabe, Tatsumi; Yamamoto, Yoshio

    2015-10-01

    Dopamine modulates the chemosensitivity of arterial chemoreceptors, and dopamine D2 receptor (D2R) is expected to localize in the glomus cells and/or sensory nerve endings of the carotid body. In the present study, the localization of D2R in the rat carotid body was examined using double immunofluorescence for D2R with various cell markers. D2R immunoreactivity was mainly localized in glomus cells immunoreactive to tyrosine hydroxylase or dopamine β-hydroxylase (DBH), but not in S100B-immunoreactive sustentacular cells. Furthermore, D2R immunoreactivity was observed in petrosal ganglion cells and nerve bundles in the carotid body, but not in the nerve endings with P2X2 immunoreactivity. In the carotid ganglion, a few punctate D2R-immunoreactive products were detected in DBH-immunoreactive nerve cell bodies. These results showed that D2R was mainly distributed in glomus cells, and suggested that D2R plays a role in the inhibitory modulation of chemosensory activity in a paracrine and/or autocrine manner. PMID:26272445

  9. Chronic exposure to perfluorooctane sulfonate induces behavior defects and neurotoxicity through oxidative damages, in vivo and in vitro.

    Directory of Open Access Journals (Sweden)

    Na Chen

    Full Text Available Perfluorooctane sulfonate (PFOS is an emerging persistent pollutant which shows multiple adverse health effects. However, the neurotoxicity of PFOS and its mechanisms have not been fully elucidated. Using a combination of in vivo and in vitro methods, the present study provides a detailed description of PFOS-induced neurotoxicity. Results showed that the median lethal concentration of PFOS was 2.03 mM in Caenorhabditis elegans for 48 h exposure. 20 µM PFOS caused decrease of locomotor behaviors including forward movement, body bend and head thrash. Additionally, PFOS exposure reduced chemotaxis index of C. elegans, which indicates the decline of chemotaxis learning ability. Using green fluorescent protein (GFP labelled transgenic strains, we found that PFOS caused down-regulated expression of a chemoreceptor gene, gcy-5, in ASE chemosensory neurons, but did not affect cholinergic neurons and dopaminergic neurons. In SH-SY5Y cells, 48 h exposure to 25 µM and 50 µM PFOS induced cell damage, apoptosis and the reactive oxygen species (ROS generation. PFOS caused significant increases of lipid peroxidation and superoxide dismutase activity, but an actual decrease of glutathione peroxidase activity. Furthermore, antioxidant N-acetylcysteine rescued cells from PFOS-induced apoptosis via blocking ROS. Our results demonstrate that chronic exposure to PFOS can cause obvious neurotoxicity and behavior defects. Oxidative damage and anti-oxidative deficit are crucial mechanisms in neurotoxicity of PFOS.

  10. Neural Control of Blood Pressure in Chronic Intermittent Hypoxia.

    Science.gov (United States)

    Shell, Brent; Faulk, Katelynn; Cunningham, J Thomas

    2016-03-01

    Sleep apnea (SA) is increasing in prevalence and is commonly comorbid with hypertension. Chronic intermittent hypoxia is used to model the arterial hypoxemia seen in SA, and through this paradigm, the mechanisms that underlie SA-induced hypertension are becoming clear. Cyclic hypoxic exposure during sleep chronically stimulates the carotid chemoreflexes, inducing sensory long-term facilitation, and drives sympathetic outflow from the hindbrain. The elevated sympathetic tone drives hypertension and renal sympathetic activity to the kidneys resulting in increased plasma renin activity and eventually angiotensin II (Ang II) peripherally. Upon waking, when respiration is normalized, the sympathetic activity does not diminish. This is partially because of adaptations leading to overactivation of the hindbrain regions controlling sympathetic outflow such as the nucleus tractus solitarius (NTS), and rostral ventrolateral medulla (RVLM). The sustained sympathetic activity is also due to enhanced synaptic signaling from the forebrain through the paraventricular nucleus (PVN). During the waking hours, when the chemoreceptors are not exposed to hypoxia, the forebrain circumventricular organs (CVOs) are stimulated by peripherally circulating Ang II from the elevated plasma renin activity. The CVOs and median preoptic nucleus chronically activate the PVN due to the Ang II signaling. All together, this leads to elevated nocturnal mean arterial pressure (MAP) as a response to hypoxemia, as well as inappropriately elevated diurnal MAP in response to maladaptations. PMID:26838032

  11. Diencephalic regulation of respiration and arterial pressure during actual and fictive locomotion in cat.

    Science.gov (United States)

    Millhorn, D E; Eldridge, F L; Waldrop, T G; Kiley, J P

    1987-10-01

    The purpose of this study was to examine by experimentation the hypothesis that the respiratory and circulatory responses during exercise are attributable to command signals that emanate from the suprapontine brain. We studied the relations between locomotion (exercise) and phrenic nerve activity and arterial pressure in cats that walked or ran on a treadmill and in animals during fictive locomotion, i.e., locomotor activity in motor nerves to legs. Anesthetized cats with intact brains and unanesthetized decorticated cats were used. All preparations exhibited spontaneous actual and fictive locomotion. Electrical stimulation or microinjection of picrotoxin, a GABA antagonist, of the subthalamic locomotor areas always caused locomotion to develop. Phrenic nerve activity and arterial pressure increased in proportion to the level of locomotor activity despite control or ablation of feedback signals from chemoreceptors and vagal receptors. Similar relations were measured during fictive locomotion despite the absence of muscular contraction and limb movement and the lack of change in metabolic rate. These findings provide experimental support for the central command hypothesis for the genesis of the respiratory hyperpnea and increased cardiovascular function that occur during exercise. We believe that the command signals emanate from the subthalamic locomotor area of the diencephalon. PMID:3652403

  12. Fos-like protein is induced in neurons of the medulla oblongata after stimulation of the carotid sinus nerve in awake and anesthetized rats.

    Science.gov (United States)

    Erickson, J T; Millhorn, D E

    1991-12-13

    The protooncogene c-fos is expressed rapidly, transiently and polysynaptically within neurons in response to synaptic activation and voltage-gated calcium entry into the cell. The nuclear protein product of this gene (Fos) is detectable immunohistochemically 20-90 min after cell activation and remains within the nucleus for hours after expression. The present study was undertaken to identify cells within the rat medulla oblongata that express Fos-like protein in response to stimulation of afferent fibers of the carotid sinus nerve (CSN). Direct electrical stimulation of the CSN in anesthetized animals or hypoxic stimulation in either anesthetized or awake animals resulted in a consistent and discrete distribution of Fos-like immunoreactivity (Fos-LI). Fos-LI was observed bilaterally within nucleus tractus solitarius (NTS) and the ventrolateral medulla (VLM), within area postrema and nucleus raphe pallidus, and bilaterally along the ventral medullary surface. Unstimulated animals were devoid of Fos-LI within the medulla oblongata. Furthermore, neither the surgical preparations alone nor the effects of anesthesia could account for the extent of Fos-LI observed. We believe these cells represent second- and higher-order neurons within the baroreceptor and chemoreceptor reflex pathways. PMID:1815818

  13. Activation of the c-fos gene in prodynorphin- and proenkephalin-expressing cells of nucleus tractus solitarius after seizures.

    Science.gov (United States)

    Kanter, R K; Erickson, J T; Millhorn, D E

    1994-10-01

    We performed studies to determine the anatomical regions and chemical phenotypes of neurons within the rat medulla oblongata activated by pentylenetetrazole-induced seizures. Activated cells were identified by their expression of the c-fos gene, detected by in situ hybridization for c-fos mRNA and immunocytochemistry for Fos protein. Activated cells were located predominantly in nucleus tractus solitarius (NTS), with c-fos mRNA appearing within 20 min after seizures (peak at 1-2 h), followed by Fos immunoreactivity visible at 1 h (peak at 2-4 h). Neither nonspecific noxious stimulation by intraperitoneal injection of saline nor brief exposure to hypoxic or hypercapnic gas mixtures to stimulate chemoreceptors reproduced this pattern of labeling. Prodynorphin or proenkephalin mRNA, detected by in situ hybridization, was colocalized with Fos immunoreactivity in many NTS cells. Thus, seizures activate neuronal pathways in the medulla oblongata which express genes for endogenous opioids. Potential long-term effects of seizures are suggested by the in situ hybridization finding that NTS prodynorphin mRNA increased 24 h after seizures compared to control levels. PMID:7957742

  14. Ontogeny of the O2-sensitive pathway in medulla oblongata of postnatal rat.

    Science.gov (United States)

    White, L D; Lawson, E E; Millhorn, D E

    1994-10-01

    Fos protein, the product of the immediate early gene c-fos, has been used as a metabolic marker to map the O2 chemosensory pathway activated by hypoxia in the adult rat (Erickson and Millhorn, Brain Res. 567: 11-24, 1991). The current study provides evidence that the O2 chemoreceptor pathway develops during the first postnatal month. Rats at postnatal ages (P) 3, 7, 10, 14, 21, and 28 days were exposed for 3 h to 21% (control) or 10% (hypoxia) O2. Pups were transcardially fixed, brain stems were frozen, sectioned, then reacted with Fos primary antibody, a secondary antibody, avidin-biotin peroxidase, then Ni-DAB as chromogen. Cells showing Fos-like immunoreactivity (Fos-LI) under control and hypoxic conditions were counted in the nucleus tractus solitarii (NTS) and the ventrolateral medulla (VLM). In both areas there was initially a low basal level of Fos-LI, a peak at P10 and a decline to P28. At all ages there was a significant increase in the number of Fos-LI cells in pups exposed to hypoxia. The high basal level of Fos expression at P10 and the high induced level at P14 may correlate with periods of terminal differentiation and maximum synaptogenesis, respectively. PMID:7817045

  15. Chemodectoma in dogs

    International Nuclear Information System (INIS)

    Tumors of the chemoreceptor organs are referred to as chemodectomas. Such tumors develop principally in the aortic and carotid bodies of animals. Aortic body tumors occur four times more frequently than do carotid body tumors. Brachycephalic breeds (e.g., boxers, Boston terriers, and English bulldogs) are over represented among reported cases of canine chemodectoma. Old male dogs are at greater risk of developing the condition. Tumors of the aortic body occur more often as single or multiple nodules in the pericardial sac near the base of the heart. Carotid body tumors arise near the bifurcation of the common carotid artery in the cranial cervical region. Clinical signs at presentation include signs of right-sided congestive heart failure (aortic body tumor) and the presence of a neck mass (carotid body tumor). In the absence of necropsy, definitive diagnosis is usually based on exploratory surgery and histopathology of surgically excised tissue. Currently, early surgical excision is the preferred treatment. Radiation therapy has been used in a limited number of cases. The prognosis for animals diagnosed with chemodectoma is guarded to fair

  16. Tratamiento de la emesis inducida por quimioterapia Treatment of emesis induced by chemotherapy

    Directory of Open Access Journals (Sweden)

    R. Vera

    2004-01-01

    Full Text Available Las náuseas y los vómitos son el efecto secundario más frecuente en los pacientes en tratamiento quimioterápico, hasta el punto que pueden llegar a hacer que se suspenda el tratamiento. La fisiología del vómito inducido por quimioterapia no está bien conocida, pero se relaciona con receptores localizados en la Chemoreceptor Trigger Zone (CTZ, y que van a ser la diana de los tratamientos. El principal factor desencadenante del vómito es el fármaco quimioterápico, que según su potencia emetógena se clasifican en: riesgo alto, intermedio o bajo. Otros factores son dependientes del propio paciente. Según el momento de aparición de los vómitos se habla de emesis aguda, si ocurre en las primeras 24 horas; de emesis retardada, si ocurre tras las primeras 16-24 horas, o de emesis anticipatoria, que se produce antes de la administración de quimioterapia, y se debe a un reflejo condicionado. Los fármacos más eficaces en el tratamiento de los vómitos relacionados con quimioterapia, son los antagonistas de los receptores de serotonina (ondansetrón, granisetrón, dolasetrón, solos o en combinación con corticoides. Los antagonistas de los receptores de dopamina (metoclopramida, son menos eficaces a las dosis habituales. Precisan de dosis altas y presentan mayores efectos secundarios. Recientemente se ha comercializado el aprepitant, un antagonista selectivo de los receptores NK1 de las neurocininas. Este medicamento, asociado a una terapia estándar de corticoides y antagonistas de los receptores de serotonina, es capaz de incrementer la respuesta antiemética en pacientes sometidos a quimioterapia altamente emetógena.Nausea and vomiting are the most frequent secondary effect in patients receiving chemotheraphy treatment, to such a degree that they can result in the treatment being suspended. The physiology of the vomiting induced by chemotherapy is not well known, but it is related to localised receptors of Chemoreceptor Trigger Zone

  17. Chemical speciation of heavy metals by surface-enhanced Raman scattering spectroscopy: identification and quantification of inorganic- and methyl-mercury in water

    Science.gov (United States)

    Guerrini, Luca; Rodriguez-Loureiro, Ignacio; Correa-Duarte, Miguel A.; Lee, Yih Hong; Ling, Xing Yi; García de Abajo, F. Javier; Alvarez-Puebla, Ramon A.

    2014-06-01

    Chemical speciation of heavy metals has become extremely important in environmental and analytical research because of the strong dependence that toxicity, environmental mobility, persistence and bioavailability of these pollutants have on their specific chemical forms. Novel nano-optical-based detection strategies, capable of overcoming the intrinsic limitations of well-established analytic methods for the quantification of total metal ion content, have been reported, but the speciation of different chemical forms has not yet been achieved. Here, we report the first example of a SERS-based sensor for chemical speciation of toxic metal ions in water at trace levels. Specifically, the inorganic Hg2+ and the more toxicologically relevant methylmercury (CH3Hg+) are selected as analytical targets. The sensing platform consists of a self-assembled monolayer of 4-mercaptopyridine (MPY) on highly SERS-active and robust hybrid plasmonic materials formed by a dense layer of interacting gold nanoparticles anchored onto polystyrene microbeads. The co-ordination of Hg2+ and CH3Hg+ to the nitrogen atom of the MPY ring yields characteristic changes in the vibrational SERS spectra of the organic chemoreceptor that can be qualitatively and quantitatively correlated to the presence of the two different mercury forms.Chemical speciation of heavy metals has become extremely important in environmental and analytical research because of the strong dependence that toxicity, environmental mobility, persistence and bioavailability of these pollutants have on their specific chemical forms. Novel nano-optical-based detection strategies, capable of overcoming the intrinsic limitations of well-established analytic methods for the quantification of total metal ion content, have been reported, but the speciation of different chemical forms has not yet been achieved. Here, we report the first example of a SERS-based sensor for chemical speciation of toxic metal ions in water at trace levels

  18. Evidence of a suffocation alarm system within the periaqueductal gray matter of the rat.

    Science.gov (United States)

    Schimitel, F G; de Almeida, G M; Pitol, D N; Armini, R S; Tufik, S; Schenberg, L C

    2012-01-01

    Dyspnea, hunger for air, and urge to flee are the cardinal symptoms of panic attacks. Patients also show baseline respiratory abnormalities and a higher rate of comorbid and antecedent respiratory diseases. Panic attacks are also precipitated by infusion of sodium lactate and inhalation of 5% CO₂ in predisposed patients but not in healthy volunteers or patients without panic disorder. Accordingly, Klein [Klein (1993) Arch Gen Psychiatry 50:306-317] suggested that clinical panic is the misfiring of an as-yet-unidentified suffocation alarm system. In rats, selective anoxia of chemoreceptor cells by potassium cyanide (KCN) and electrical and chemical stimulations of periaqueductal gray matter (PAG) produce defensive behaviors, which resemble panic attacks. Thus, here we examined the effects of single or combined administrations of CO₂ (8% and 13%) and KCN (10-80 μg, i.v.) on spontaneous and PAG-evoked behaviors of rats either intact or bearing electrolytic lesions of PAG. Exposure to CO₂ alone reduced grooming while increased exophthalmus, suggesting an arousal response to non-visual cues of environment. Unexpectedly, however, CO₂ attenuated PAG-evoked immobility, trotting, and galloping while facilitated defecation and micturition. Conversely, KCN produced all defensive behaviors of the rat and facilitated PAG-evoked trotting, galloping, and defecation. There were also facilitatory trends in PAG-evoked exophthalmus, immobility, and jumping. Moreover, whereas the KCN-evoked defensive behaviors were attenuated or even suppressed by discrete lesions of PAG, they were markedly facilitated by CO₂. Authors suggest that the PAG harbors an anoxia-sensitive suffocation alarm system which activation precipitates panic attacks and potentiates the subject responses to hypercapnia. PMID:22062132

  19. Testing the hypothesis of neurodegeneracy in respiratory network function with a priori transected arterially perfused brain stem preparation of rat.

    Science.gov (United States)

    Jones, Sarah E; Dutschmann, Mathias

    2016-05-01

    Degeneracy of respiratory network function would imply that anatomically discrete aspects of the brain stem are capable of producing respiratory rhythm. To test this theory we a priori transected brain stem preparations before reperfusion and reoxygenation at 4 rostrocaudal levels: 1.5 mm caudal to obex (n = 5), at obex (n = 5), and 1.5 (n = 7) and 3 mm (n = 6) rostral to obex. The respiratory activity of these preparations was assessed via recordings of phrenic and vagal nerves and lumbar spinal expiratory motor output. Preparations with a priori transection at level of the caudal brain stem did not produce stable rhythmic respiratory bursting, even when the arterial chemoreceptors were stimulated with sodium cyanide (NaCN). Reperfusion of brain stems that preserved the pre-Bötzinger complex (pre-BötC) showed spontaneous and sustained rhythmic respiratory bursting at low phrenic nerve activity (PNA) amplitude that occurred simultaneously in all respiratory motor outputs. We refer to this rhythm as the pre-BötC burstlet-type rhythm. Conserving circuitry up to the pontomedullary junction consistently produced robust high-amplitude PNA at lower burst rates, whereas sequential motor patterning across the respiratory motor outputs remained absent. Some of the rostrally transected preparations expressed both burstlet-type and regular PNA amplitude rhythms. Further analysis showed that the burstlet-type rhythm and high-amplitude PNA had 1:2 quantal relation, with burstlets appearing to trigger high-amplitude bursts. We conclude that no degenerate rhythmogenic circuits are located in the caudal medulla oblongata and confirm the pre-BötC as the primary rhythmogenic kernel. The absence of sequential motor patterning in a priori transected preparations suggests that pontine circuits govern respiratory pattern formation. PMID:26888109

  20. Parasympathetic preganglionic cardiac motoneurons labeled after voluntary diving

    Directory of Open Access Journals (Sweden)

    W Michael ePanneton

    2014-01-01

    Full Text Available A dramatic bradycardia is induced by underwater submersion in vertebrates. The location of parasympathetic preganglionic cardiac motor neurons driving this aspect of the diving response was investigated using cFos immunohistochemistry combined with retrograde transport of cholera toxin subunit B (CTB to double-label neurons. After pericardial injections of CTB, trained rats voluntarily dove underwater, and their heart rates dropped immediately to 95±2bpm, an 80% reduction. After immunohistochemical processing, the vast majority of CTB labeled neurons were located in the reticular formation from the rostral cervical spinal cord to the facial motor nucleus, confirming previous studies. Labeled neurons caudal to the rostral ventrolateral medulla were usually spindle-shaped aligned along an oblique line running from the dorsal vagal nucleus to the ventrolateral reticular formation, while those more rostrally were multipolar with extended dendrites. Nine percent of retrogradely-labeled neurons were positive for both cFos and CTB after diving and 74% of these were found rostral to the obex. CTB also was transported transganglionically in primary afferent fibers, resulting in large granular deposits in dorsolateral, ventrolateral, and commissural subnuclei of the nucleus tractus solitarii and finer deposits in lamina I and IV-V of the trigeminocervical complex. The overlap of parasympathetic preganglionic cardiac motor neurons activated by diving with those activated by baro- and chemoreceptors in the rostral ventrolateral medulla is discussed. Thus the profound bradycardia seen with underwater submersion reinforces the notion that the mammalian diving response is the most powerful autonomic reflex known.

  1. Force-dependent discharge of nematocysts in the sea anemone Haliplanella luciae (Verrill

    Directory of Open Access Journals (Sweden)

    Dustin Todaro

    2012-05-01

    Sea anemones discharge cnidae (‘stinging capsules’ including nematocysts to capture prey and to defend themselves. In the present study, we tested the relationship between the force of test probes striking feeding tentacles and discharge of microbasic p-mastigophore nematocysts into the test probes. In seawater alone, the response curve is bimodal with maximal discharge observed at 0.33 and 1.10 millinewtons (mN and with minimal discharge at 1.50 mN. Upon activating chemoreceptors for N-acetylated sugars, maximal discharge is observed across a broad range of smaller forces from 0.16 to 0.9 mN before decreasing to a minimum at 1.50 mN. Likewise, in the presence of nearby vibrations at key frequencies, maximal discharge is observed over a broad range of smaller forces before decreasing to a minimum at 1.50 mN. It appears that sensory input indicating proximity of potential prey expands the range of small forces of impact that stimulate maximal discharge (i.e. to less than 1.10 mN but not at larger forces of impact (i.e. at approximately 1.50 mN. Thus, contact by small prey would stimulate maximal discharge, and all the more so if such contact is accompanied by specific odorants or by vibrations at specific frequencies. Nevertheless, anemones would not maximally discharge nematocysts into large animals that blunder into contact with their tentacles.

  2. Expression of taste receptors in Solitary Chemosensory Cells of rodent airways

    Directory of Open Access Journals (Sweden)

    Sbarbati Andrea

    2011-01-01

    Full Text Available Abstract Background Chemical irritation of airway mucosa elicits a variety of reflex responses such as coughing, apnea, and laryngeal closure. Inhaled irritants can activate either chemosensitive free nerve endings, laryngeal taste buds or solitary chemosensory cells (SCCs. The SCC population lies in the nasal respiratory epithelium, vomeronasal organ, and larynx, as well as deeper in the airway. The objective of this study is to map the distribution of SCCs within the airways and to determine the elements of the chemosensory transduction cascade expressed in these SCCs. Methods We utilized a combination of immunohistochemistry and molecular techniques (rtPCR and in situ hybridization on rats and transgenic mice where the Tas1R3 or TRPM5 promoter drives expression of green fluorescent protein (GFP. Results Epithelial SCCs specialized for chemoreception are distributed throughout much of the respiratory tree of rodents. These cells express elements of the taste transduction cascade, including Tas1R and Tas2R receptor molecules, α-gustducin, PLCβ2 and TrpM5. The Tas2R bitter taste receptors are present throughout the entire respiratory tract. In contrast, the Tas1R sweet/umami taste receptors are expressed by numerous SCCs in the nasal cavity, but decrease in prevalence in the trachea, and are absent in the lower airways. Conclusions Elements of the taste transduction cascade including taste receptors are expressed by SCCs distributed throughout the airways. In the nasal cavity, SCCs, expressing Tas1R and Tas2R taste receptors, mediate detection of irritants and foreign substances which trigger trigeminally-mediated protective airway reflexes. Lower in the respiratory tract, similar chemosensory cells are not related to the trigeminal nerve but may still trigger local epithelial responses to irritants. In total, SCCs should be considered chemoreceptor cells that help in preventing damage to the respiratory tract caused by inhaled irritants and

  3. Exercise training attenuates chemoreflex-mediated reductions of renal blood flow in heart failure.

    Science.gov (United States)

    Marcus, Noah J; Pügge, Carolin; Mediratta, Jai; Schiller, Alicia M; Del Rio, Rodrigo; Zucker, Irving H; Schultz, Harold D

    2015-07-15

    In chronic heart failure (CHF), carotid body chemoreceptor (CBC) activity is increased and contributes to increased tonic and hypoxia-evoked elevation in renal sympathetic nerve activity (RSNA). Elevated RSNA and reduced renal perfusion may contribute to development of the cardio-renal syndrome in CHF. Exercise training (EXT) has been shown to abrogate CBC-mediated increases in RSNA in experimental heart failure; however, the effect of EXT on CBC control of renal blood flow (RBF) is undetermined. We hypothesized that CBCs contribute to tonic reductions in RBF in CHF, that stimulation of the CBC with hypoxia would result in exaggerated reductions in RBF, and that these responses would be attenuated with EXT. RBF was measured in CHF-sedentary (SED), CHF-EXT, CHF-carotid body denervation (CBD), and CHF-renal denervation (RDNX) groups. We measured RBF at rest and in response to hypoxia (FiO2 10%). All animals exhibited similar reductions in ejection fraction and fractional shortening as well as increases in ventricular systolic and diastolic volumes. Resting RBF was lower in CHF-SED (29 ± 2 ml/min) than in CHF-EXT animals (46 ± 2 ml/min, P hypoxia, and this was prevented in CHF-EXT animals. Both CBD and RDNX abolished the RBF response to hypoxia in CHF. Mean arterial pressure increased in response to hypoxia in CHF-SED, but was prevented by EXT, CBD, and RDNX. EXT is effective in attenuating chemoreflex-mediated tonic and hypoxia-evoked reductions in RBF in CHF. PMID:26001414

  4. Sympatric speciation revealed by genome-wide divergence in the blind mole rat Spalax.

    Science.gov (United States)

    Li, Kexin; Hong, Wei; Jiao, Hengwu; Wang, Guo-Dong; Rodriguez, Karl A; Buffenstein, Rochelle; Zhao, Yang; Nevo, Eviatar; Zhao, Huabin

    2015-09-22

    Sympatric speciation (SS), i.e., speciation within a freely breeding population or in contiguous populations, was first proposed by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection] and is still controversial despite theoretical support [Gavrilets S (2004) Fitness Landscapes and the Origin of Species (MPB-41)] and mounting empirical evidence. Speciation of subterranean mammals generally, including the genus Spalax, was considered hitherto allopatric, whereby new species arise primarily through geographic isolation. Here we show in Spalax a case of genome-wide divergence analysis in mammals, demonstrating that SS in continuous populations, with gene flow, encompasses multiple widespread genomic adaptive complexes, associated with the sharply divergent ecologies. The two abutting soil populations of S. galili in northern Israel habituate the ancestral Senonian chalk population and abutting derivative Plio-Pleistocene basalt population. Population divergence originated ∼0.2-0.4 Mya based on both nuclear and mitochondrial genome analyses. Population structure analysis displayed two distinctly divergent clusters of chalk and basalt populations. Natural selection has acted on 300+ genes across the genome, diverging Spalax chalk and basalt soil populations. Gene ontology enrichment analysis highlights strong but differential soil population adaptive complexes: in basalt, sensory perception, musculature, metabolism, and energetics, and in chalk, nutrition and neurogenetics are outstanding. Population differentiation of chemoreceptor genes suggests intersoil population's mate and habitat choice substantiating SS. Importantly, distinctions in protein degradation may also contribute to SS. Natural selection and natural genetic engineering [Shapiro JA (2011) Evolution: A View From the 21st Century] overrule gene flow, evolving divergent ecological adaptive complexes. Sharp ecological divergences abound in nature; therefore, SS appears to be an

  5. Physiological and Clinical Implications of Adrenergic Pathways at High Altitude.

    Science.gov (United States)

    Richalet, Jean-Paul

    2016-01-01

    The adrenergic system is part of a full array of mechanisms allowing the human body to adapt to the hypoxic environment. Triggered by the stimulation of peripheral chemoreceptors, the adrenergic centers in the medulla are activated in acute hypoxia and augment the adrenergic drive to the organs, especially to the heart, leading to tachycardia. With prolonged exposure to altitude hypoxia, the adrenergic drive persists, as witnessed by elevated blood concentrations of catecholamines and nerve activity in adrenergic fibers. In response to this persistent stimulation, the pathways leading to the activation of adenylate cyclase are modified. A downregulation of β-adrenergic and adenosinergic receptors is observed, while muscarinic receptors are upregulated. The expression and activity of Gi and Gs proteins are modified, leading to a decreased response of adenylate cyclase activity to adrenergic stimulation. The clinical consequences of these cellular and molecular changes are of importance, especially for exercise performance and protection of heart function. The decrease in maximal exercise heart rate in prolonged hypoxia is fully accounted for the observed changes in adrenergic and muscarinic pathways. The decreased heart rate response to isoproterenol infusion is another marker of the desensitization of adrenergic pathways. These changes can be considered as mechanisms protecting the heart from a too high oxygen consumption in conditions where the oxygen availability is severely reduced. Similarly, intermittent exposure to hypoxia has been shown to protect the heart from an ischemic insult with similar mechanisms involving G proteins and downregulation of β receptors. Other pathways with G proteins are concerned in adaptation to hypoxia, such as lactate release by the muscles and renal handling of calcium. Altogether, the activation of the adrenergic system is useful for the acute physiological response to hypoxia. With prolonged exposure to hypoxia, the autonomous

  6. Ventilatory response to high inspired carbon dioxide concentrations in anesthetized dogs

    Directory of Open Access Journals (Sweden)

    Jack A. Loeppky

    2011-02-01

    Full Text Available Background: The ventilation (IV response to inspired CO2 has been extensively studied, but rarely with concentrations >10%. Aims: These experiments were performed to determine whether I V  would increase correspondingly to higher concentrations and according to conventional chemoreceptor time delays. Materials and Methods: We exposed anesthetized dogs acutely, with and without vagotomy and electrical stimulation of the right vagus, to 20-100% CO2-balance O2.and to 0 and 10% O2-balance N2. Results: The I V  time delays decreased and response magnitude increased with increasing concentrations (p<0.01, but at higher concentrations the time delays were shorter than expected, i.e., 0.5 s to double I V  at 100% CO2, with the response to 0% O2 being 3 s slower. Right vagotomy significantly reduced baseline breathing frequency (fR, increased tidal volume (VT and increased the time delay by 3 s. Bilateral vagotomy further reduced baseline fR and I V  , and reduced the response to CO2 and increased the time delay by 12 s. Electro-stimulation of the peripheral right vagus while inspiring CO2 caused a 13 s asystole and further reduced and delayed the I V  response, especially after bilateral vagotomy, shifting the mode from VT to fR. Conclusions: Results indicate that airway or lung receptors responded to the rapid increase in lung H+ and that vagal afferents and unimpaired circulation seem necessary for the initial rapid response to high CO2 concentrations by receptors upstream from the aortic bodies.

  7. Variation of chemosensory receptor content of Campylobacter jejuni strains and modulation of receptor gene expression under different in vivo and in vitro growth conditions

    Directory of Open Access Journals (Sweden)

    Day Christopher J

    2012-06-01

    Full Text Available Abstract Background Chemotaxis is crucial for the colonisation/infection of hosts with Campylobacter jejuni. Central to chemotaxis are the group A chemotaxis genes that are responsible for sensing the external environment. The distribution of group A chemoreceptor genes, as found in the C. jejuni sequenced strains, tlp1-4, 7, 10 and 11 were determined in 33 clinical human and avian isolates. Results Group A tlp gene content varied among the strains with genes encoding tlp1 (aspartate receptor, ccaA and tlp7 present in all strains tested, where as tlp11 was present in only one of our international collection clinical isolates, C. jejuni 520, but was more prevalent (9/13 in the freshly isolated clinical stains from patients who required hospitalisation due to C. jejuni infection (GCH1-17. Relative expression levels of the group A tlp genes were also determined in C. jejuni reference strains NCTC 11168-GS, 11168-O and 81116 using cells grown in vitro at 37°C, 42°C and maintained at room temperature and with cells isolated directly from murine and avian hosts by immune magnetic separation without subsequent culture. Gene expression of tlp genes was varied based on strain, growth conditions and in vivo isolation source. Tlp1, although the most conserved, showed the lowest and most varied mRNA expression and protein production under laboratory conditions. Tlp7 was highly expressed at most conditions tested, and gene expression was not influenced by the tlp7 gene encoding a full length protein or one expressed as separate periplasmic and cytoplasmic domains. Conclusion We have shown that chemosensory receptor set variation exists among C. jejuni strains, but is not dependent on the isolation source.

  8. An Intracellular Nanotrap Redirects Proteins and Organelles in Live Bacteria

    Science.gov (United States)

    Borg, Sarah; Popp, Felix; Hofmann, Julia; Leonhardt, Heinrich; Rothbauer, Ulrich

    2015-01-01

    ABSTRACT  Owing to their small size and enhanced stability, nanobodies derived from camelids have previously been used for the construction of intracellular “nanotraps,” which enable redirection and manipulation of green fluorescent protein (GFP)-tagged targets within living plant and animal cells. By taking advantage of intracellular compartmentalization in the magnetic bacterium Magnetospirillum gryphiswaldense, we demonstrate that proteins and even entire organelles can be retargeted also within prokaryotic cells by versatile nanotrap technology. Expression of multivalent GFP-binding nanobodies on magnetosomes ectopically recruited the chemotaxis protein CheW1-GFP from polar chemoreceptor clusters to the midcell, resulting in a gradual knockdown of aerotaxis. Conversely, entire magnetosome chains could be redirected from the midcell and tethered to one of the cell poles. Similar approaches could potentially be used for building synthetic cellular structures and targeted protein knockdowns in other bacteria. Importance   Intrabodies are commonly used in eukaryotic systems for intracellular analysis and manipulation of proteins within distinct subcellular compartments. In particular, so-called nanobodies have great potential for synthetic biology approaches because they can be expressed easily in heterologous hosts and actively interact with intracellular targets, for instance, by the construction of intracellular “nanotraps” in living animal and plant cells. Although prokaryotic cells also exhibit a considerable degree of intracellular organization, there are few tools available equivalent to the well-established methods used in eukaryotes. Here, we demonstrate the ectopic retargeting and depletion of polar membrane proteins and entire organelles to distinct compartments in a magnetotactic bacterium, resulting in a gradual knockdown of magneto-aerotaxis. This intracellular nanotrap approach has the potential to be applied in other bacteria for

  9. The breathing pattern and the ventilatory response to aquatic and aerial hypoxia and hypercarbia in the frog Pipa carvalhoi.

    Science.gov (United States)

    Fonseca, Elisa M; da Silva, Glauber S F; Fernandes, Marcelo; Giusti, Humberto; Noronha-de-Souza, Carolina R; Glass, Mogens L; Bícego, Kênia C; Gargaglioni, Luciane H

    2012-07-01

    Anuran amphibians are known to exhibit an intermittent pattern of pulmonary ventilation and to exhibit an increased ventilatory response to hypoxia and hypercarbia. However, only a few species have been studied to date. The aquatic frog Pipa carvalhoi inhabits lakes, ponds and marshes that are rich in nutrients but low in O(2). There are no studies of the respiratory pattern of this species and its ventilation during hypoxia or hypercarbia. Accordingly, the aim of the present study was to characterize the breathing pattern and the ventilatory response to aquatic and aerial hypoxia and hypercarbia in this species. With this purpose, pulmonary ventilation (V(I)) was directly measured by the pneumotachograph method during normocapnic normoxia to determine the basal respiratory pattern and during aerial and aquatic hypercarbia (5% CO(2)) and hypoxia (5% O(2)). Our data demonstrate that P. carvalhoi exhibits a periodic breathing pattern composed of single events (single breaths) of pulmonary ventilation separated by periods of apnea. The animals had an enhanced V(I) during aerial hypoxia, but not during aquatic hypoxia. This increase was strictly the result of an increase in the breathing frequency. A pronounced increase in V(I) was observed if the animals were simultaneously exposed to aerial and aquatic hypercarbia, whereas small or no ventilatory responses were observed during separately administered aerial or aquatic hypercarbia. P. carvalhoi primarily inhabits an aquatic environment. Nevertheless, it does not respond to low O(2) levels in water, although it does so in air. The observed ventilatory responses to hypercarbia may indicate that this species is similar to other anurans in possessing central chemoreceptors. PMID:22503869

  10. Morphological changes of carotid bodies in acute respiratory distress syndrome: a morphometric study in humans

    Directory of Open Access Journals (Sweden)

    Vinhaes E.N.G.

    2002-01-01

    Full Text Available Carotid bodies are chemoreceptors sensitive to a fall of partial oxygen pressure in blood (hypoxia. The morphological alterations of these organs in patients with chronic obstructive pulmonary disease (COPD and in people living at high altitude are well known. However, it is not known whether the histological profile of human carotid bodies is changed in acute clinical conditions such as acute respiratory distress syndrome (ARDS. The objective of the present study was to perform a quantitative analysis of the histology of carotid bodies collected from patients who died of ARDS. A morphometric study of carotid bodies collected during routine autopsies was carried out on three groups: patients that died of non-respiratory diseases (controls, N = 8, patients that presented COPD and died of its complications or associated diseases (N = 7, and patients that died of ARDS (N = 7. Morphometric measurements of the volume fraction of clusters of chief cells were performed in five fields on each slide at 40X magnification. The numerical proportion of the four main histological cell types (light, dark, progenitor and sustentacular cells was determined analyzing 10 fields on each slide at 400X magnification. The proportion of dark cells was 0.22 in ARDS patients, 0.12 in controls (P<0.001, and 0.08 in the COPD group. The proportion of light cells was 0.33 (ARDS, 0.44 (controls (P<0.001, and 0.36 (COPD. These findings suggest that chronic and acute hypoxia have different effects on the histology of glomic tissue.

  11. Anatomical description of genital organs and abdominal secreting glands of the beetle Ulomoides dermestoides (Fairmare 1893) (Coleoptera: Tenebrionidae)

    International Nuclear Information System (INIS)

    The anatomy of genital organs and abdominal glands of dermestoides Ulomoide have been described in laboratory conditions (diet of peanuts, 70% RH, 23 degrees C at 1300 msnm) to present biotechnological potential and submit pharmacological properties. The description is made in the Centro de Investigacion en Biotecnologia from the Instituto Tecnologico de Cartago, Costa Rica. The same was processed for macroscopic observation and for observing of internal structures using scanning electron microscopy (SEM) in the Unidad de Investigacion en Estructuras Microscopicas of the Universidad de Costa Rica. Ten females and ten males in adult stage were selected using stereoscope and entomological tweezers of manipulation. Digital images were captured of genital organs of each sex with the software package AverMedia EzCaptura 2,5 and equipment BioVid LWScientific, Inc. In females has been observed the mechanics of the ovipositional structure and has described reproductive functions and defense, as it has found two apical fences with sensory accumulations, meccano and chemoreceptor. Sclerotic internal structures have been reported to function in oviposition, as well as guides along with the elastic tissue of the oviduct form the final segment of the ovipositor. In males adeago has been identified, your internal extensions and particular form that allows its introduction and coupling during intercourse, also serving as guide surface of defensive secretions. The micrographs showed the presence of corrugated secreting glands in both sexes (1,05 mm long by 350 mm diameter) with strong adhesion to the abdominal wall by muscular tissue of convergence of secretory ducts associated with gonopore communication with glandular receptacle. Bacterial cells apparently have found inside the glands, this as possible pathological infection or as symbiotic organisms, which could not be clearly distinguished. The secretions were associated with a defense mechanism of the species, as the genital

  12. Ventilatory compensation of the alkaline tide during digestion in the snake Boa constrictor.

    Science.gov (United States)

    Andrade, Denis V; De Toledo, Luis Felipe; Abe, Augusto S; Wang, Tobias

    2004-03-01

    The increased metabolic rate during digestion is associated with changes in arterial acid-base parameters that are caused by gastric acid secretion (the 'alkaline tide'). Net transfer of HCl to the stomach lumen causes an increase in plasma HCO3- levels, but arterial pH does not change because of a ventilatory compensation that counters the metabolic alkalosis. It seems, therefore, that ventilation is controlled to preserve pH and not PCO2 during the postprandial period. To investigate this possibility, we determined arterial acid-base parameters and the metabolic response to digestion in the snake Boa constrictor, where gastric acid secretion was inhibited pharmacologically by oral administration of omeprazole. The increase in oxygen consumption of omeprazole-treated snakes after ingestion of 30% of their own body mass was quantitatively similar to the response in untreated snakes, although the peak of the metabolic response occurred later (36 h versus 24 h). Untreated control animals exhibited a large increase in arterial plasma HCO3- concentration of approximately 12 mmol l(-1), but arterial pH only increased by 0.12 pH units because of a simultaneous increase in arterial PCO2 by about 10 mmHg. Omeprazole virtually abolished the changes in arterial pH and plasma HCO3- concentration during digestion and there was no increase in arterial PCO2. The increased arterial PCO2 during digestion is not caused, therefore, by the increased metabolism during digestion or a lower ventilatory responsiveness to ventilatory stimuli during a presumably relaxed state in digestion. Furthermore, the constant arterial PCO2, in the absence of an alkaline tide, of omeprazole-treated snakes strongly suggests that pH rather than PCO2 normally affects chemoreceptor activity and ventilatory drive. PMID:15010489

  13. Succinate dehydrogenase subunit D and succinate dehydrogenase subunit B mutation analysis in canine phaeochromocytoma and paraganglioma.

    Science.gov (United States)

    Holt, D E; Henthorn, P; Howell, V M; Robinson, B G; Benn, D E

    2014-07-01

    Phaeochromocytomas (PCs) are tumours of the adrenal medulla chromaffin cells. Paragangliomas (PGLs) arise in sympathetic ganglia (previously called extra-adrenal PCs) or in non-chromaffin parasympathetic ganglia cells that are usually non-secretory. Parenchymal cells from these tumours have a common embryological origin from neural crest ectoderm. Several case series of canine PCs and PGLs have been published and a link between the increased incidence of chemoreceptor neoplasia in brachycephalic dog breeds and chronic hypoxia has been postulated. A similar link to hypoxia in man led to the identification of germline heterozygous mutations in the gene encoding succinate dehydrogenase subunit D (SDHD) and subsequently SDHA, SDHB and SDHC in similar tumours. We investigated canine PCs (n = 6) and PGLs (n = 2) for SDHD and SDHB mutations and in one PGL found a somatic SDHD mutation c.365A>G (p.Lys122Arg) in exon 4, which was not present in normal tissue from this brachycephalic dog. Two PCs were heterozygous for both c.365A>G (p.Lys122Arg) mutation and an exon 3 silent variant c.291G>A. We also identified the heterozygous SDHB exon 2 mutation c.113G>A (p.Arg38Gln) in a PC. These results illustrate that genetic mutations may underlie tumourigenesis in canine PCs and PGLs. The spontaneous nature of these canine diseases and possible association of PGLs with hypoxia in brachycephalic breeds may make them an attractive model for studying the corresponding human tumours. PMID:24813157

  14. Autonomic processing of the cardiovascular reflexes in the nucleus tractus solitarii

    Directory of Open Access Journals (Sweden)

    Machado B.H.

    1997-01-01

    Full Text Available The nucleus tractus solitarii (NTS receives afferent projections from the arterial baroreceptors, carotid chemoreceptors and cardiopulmonary receptors and as a function of this information produces autonomic adjustments in order to maintain arterial blood pressure within a narrow range of variation. The activation of each of these cardiovascular afferents produces a specific autonomic response by the excitation of neuronal projections from the NTS to the ventrolateral areas of the medulla (nucleus ambiguus, caudal and rostral ventrolateral medulla. The neurotransmitters at the NTS level as well as the excitatory amino acid (EAA receptors involved in the processing of the autonomic responses in the NTS, although extensively studied, remain to be completely elucidated. In the present review we discuss the role of the EAA L-glutamate and its different receptor subtypes in the processing of the cardiovascular reflexes in the NTS. The data presented in this review related to the neurotransmission in the NTS are based on experimental evidence obtained in our laboratory in unanesthetized rats. The two major conclusions of the present review are that a the excitation of the cardiovagal component by cardiovascular reflex activation (chemo- and Bezold-Jarisch reflexes or by L-glutamate microinjection into the NTS is mediated by N-methyl-D-aspartate (NMDA receptors, and b the sympatho-excitatory component of the chemoreflex and the pressor response to L-glutamate microinjected into the NTS are not affected by an NMDA receptor antagonist, suggesting that the sympatho-excitatory component of these responses is mediated by non-NMDA receptors.

  15. The distribution of presumptive thoracic paraganglionic tissue in the common marmoset (Callithrix jacchus

    Directory of Open Access Journals (Sweden)

    Clarke J.A.

    2002-01-01

    Full Text Available The aortic-pulmonary regions (APR of seven adult marmosets (Callithrix jacchus and the region of the right subclavian artery of a further three marmosets were diffusion-fixed with 10% buffered formol-saline solution. In both regions serial 5-µm sections were cut and stained by the Martius yellow, brilliant crystal scarlet and soluble blue method. Presumptive thoracic paraganglionic (PTP tissue was only observed in the APR. PTP tissue was composed of small groups of cells that varied in size and number. The distribution of the groups of cells was extremely variable, so much so that it would be misleading to attempt to classify their position; they were not circumscribed by a connective tissue capsule, but were always related to the thoracic branches of the left vagus nerve. The cells lay in loose areolar tissue characteristic of this part of the mediastinum and received their blood supply from small adjacent connective tissue arterioles. Unlike the paraganglionic tissue found in the carotid body the cells in the thorax did not appear to have a profuse capillary blood supply. There was, however, a close cellular-neural relationship. The cells, 10-15 µm in diameter, were oval or rounded in appearance and possessed a central nucleus and clear cytoplasm. No evidence was found that these cells possessed a 'companion' cell reminiscent of the arrangement of type 1 and type 2 cells in the carotid body. In conclusion, we found evidence of presumed paraganglionic tissue in the APR of the marmoset which, however, did not show the characteristic histological features of the aortic body chemoreceptors that have been described in some non-primate mammals. A survey of the mediastina of other non-human primates is required to establish whether this finding is atypical for these animals.

  16. Leptin in nucleus of the solitary tract alters the cardiovascular responses to aortic baroreceptor activation.

    Science.gov (United States)

    Ciriello, John

    2013-06-01

    Recent data suggests that neurons expressing the long form of the leptin receptor form at least two distinct groups within the caudal nucleus of the solitary tract (NTS): a group within the lateral NTS (Slt) and one within the medial (Sm) and gelantinosa (Sg) NTS. Discrete injections of leptin into Sm and Sg, a region that receives chemoreceptor input, elicit increases in arterial pressure (AP) and renal sympathetic nerve activity (RSNA). However, the effect of microinjections of leptin into Slt, a region that receives baroreceptor input is unknown. Experiments were done in the urethane-chloralose anesthetized, paralyzed and artificially ventilated Wistar or Zucker obese rat to determine leptin's effect in Slt on heart rate (HR), AP and RSNA during electrical stimulation of the aortic depressor nerve (ADN). Depressor sites within Slt were first identified by the microinjection of l-glutamate (Glu; 0.25M; 10nl) followed by leptin microinjections. In the Wistar rat leptin microinjection (50ng; 20nl) into depressor sites within the lateral Slt elicited increases in HR and RSNA, but no changes in AP. Additionally, leptin injections into Slt prior to Glu injections at the same site or to stimulation of the ADN were found to attenuate the decreases in HR, AP and RSNA to both the Glu injection and ADN stimulation. In Zucker obese rats, leptin injections into NTS depressor sites did not elicit cardiovascular responses, nor altered the cardiovascular responses elicited by stimulation of ADN. Those data suggest that leptin acts at the level of NTS to alter the activity of neurons that mediate the cardiovascular responses to activation of the aortic baroreceptor reflex. PMID:23535030

  17. Physiological and pathophysiological interactions between the respiratory central pattern generator and the sympathetic nervous system.

    Science.gov (United States)

    Molkov, Yaroslav I; Zoccal, Daniel B; Baekey, David M; Abdala, Ana P L; Machado, Benedito H; Dick, Thomas E; Paton, Julian F R; Rybak, Ilya A

    2014-01-01

    Respiratory modulation seen in the sympathetic nerve activity (SNA) implies that the respiratory and sympathetic networks interact. During hypertension elicited by chronic intermittent hypoxia (CIH), the SNA displays an enhanced respiratory modulation reflecting strengthened interactions between the networks. In this chapter, we review a series of experimental and modeling studies that help elucidate possible mechanisms of sympatho-respiratory coupling. We conclude that this coupling significantly contributes to both the sympathetic baroreflex and the augmented sympathetic activity after exposure to CIH. This conclusion is based on the following findings. (1) Baroreceptor activation results in perturbation of the respiratory pattern via transient activation of postinspiratory neurons in the Bötzinger complex (BötC). The same BötC neurons are involved in the respiratory modulation of SNA, and hence provide an additional pathway for the sympathetic baroreflex. (2) Under hypercapnia, phasic activation of abdominal motor nerves (AbN) is accompanied by synchronous discharges in SNA due to the common source of this rhythmic activity in the retrotrapezoid nucleus (RTN). CIH conditioning increases the CO2 sensitivity of central chemoreceptors in the RTN which results in the emergence of AbN and SNA discharges under normocapnic conditions similar to those observed during hypercapnia in naïve animals. Thus, respiratory-sympathetic interactions play an important role in defining sympathetic output and significantly contribute to the sympathetic activity and hypertension under certain physiological or pathophysiological conditions, and the theoretical framework presented may be instrumental in understanding of malfunctioning control of sympathetic activity in a variety of disease states. PMID:25194190

  18. Respiratory gases and the regulation of transcription.

    Science.gov (United States)

    Cummins, Eoin P; Keogh, Ciara E

    2016-08-01

    What is the topic of this review? This review highlights the transcriptional consequences for decreased cellular O2 levels (hypoxia) and increased cellular CO2 levels (hypercapnia). What advances does it highlight? We discuss recent advances in our understanding of the cellular response to hypoxia and consider the potential cross-talk between O2 - and CO2 -dependent transcriptional regulation. Oxygen and carbon dioxide are the substrate and product of aerobic metabolism, respectively. Thus, the levels of these physiological gases are inextricably linked in physiological and pathophysiological conditions. Increased mitochondrial consumption of O2 (to produce ATP) will produce more CO2 . Furthermore, in lung pathologies such as chronic obstructive pulmonary disease, sleep apnoea and central hypoventilation syndrome, hypoxia and hypercapnia are co-incident. Acute responses to hypoxia involve carotid body-mediated changes in the rate and depth of breathing. Chronic adaptation to hypoxia involves a multitude of changes on a transcriptional level, which simultaneously increases oxygen utilization (via hypoxia-inducible factor and others), while suppressing superfluous energy-demanding processes. Acute responses to CO2 affect breathing primarily via central chemoreceptors. The nature of hypercapnia-dependent transcriptional regulation is an emerging area of research, but at present the mechanisms underpinning this response are not fully characterized and understood. Thus, given the juxtaposition of hypoxia and hypercapnia in health and disease, this manuscript reviews the current evidence for transcriptional responses to hypoxia and hypercapnia. Finally, we discuss the potential cross-talk between hypoxia and hypercapnia on a transcriptional level. PMID:27474261

  19. NO INFLUENCE OF HYPOXIA ON COORDINATION BETWEEN RESPIRATORY AND LOCOMOTOR RHYTHMS DURING ROWING AT MODERATE INTENSITY

    Directory of Open Access Journals (Sweden)

    Nicolas Fabre

    2007-12-01

    Full Text Available Besides neuro-mechanical constraints, chemical or metabolic stimuli have also been proposed to interfere with the coordination between respiratory and locomotor rhythms. In the light of the conflicting data observed in the literature, this study aimed to assess whether acute hypoxia modifies the degree of coordination between respiratory and locomotor rhythms during rowing exercises in order to investigate competitive interactions between neuro-mechanical (movement and chemical (hypoxia respiratory drives. Nine male healthy subjects performed one submaximal 6-min rowing exercise on a rowing ergometer in both normoxia (altitude: 304 m and acute hypoxia (altitude: 2877 m. The exercise intensity was about 40 % and 35 % (for normoxia and hypoxia conditions, respectively of the individual maximal power output measured during an incremental rowing test to volitional exhaustion carried out in normoxia. Metabolic rate and minute ventilation were continuously collected throughout exercise. Locomotor movement and breathing rhythms were continuously recorded and synchronized cycle-by-cycle. The degree of coordination was expressed as a percentage of breaths starting during the same phase of the locomotor cycle. For a same and a constant metabolic rate, acute hypoxia did not influence significantly the degree of coordination (mean ± SEM, normoxia: 20.0 ± 6.2 %, hypoxia: 21.3 ± 11.1 %, p > 0.05 while ventilation and breathing frequency were significantly greater in hypoxia. Our results may suggest that during rowing exercise at a moderate metabolic load, neuro-mechanical locomotion-linked respiratory stimuli appear "stronger" than peripheral chemoreceptors- linked respiratory stimuli induced by hypoxia, in the context of our study

  20. Control of the Cutaneous Circulation by the Central Nervous System.

    Science.gov (United States)

    Blessing, William; McAllen, Robin; McKinley, Michael

    2016-01-01

    The central nervous system (CNS), via its control of sympathetic outflow, regulates blood flow to the acral cutaneous beds (containing arteriovenous anastomoses) as part of the homeostatic thermoregulatory process, as part of the febrile response, and as part of cognitive-emotional processes associated with purposeful interactions with the external environment, including those initiated by salient or threatening events (we go pale with fright). Inputs to the CNS for the thermoregulatory process include cutaneous sensory neurons, and neurons in the preoptic area sensitive to the temperature of the blood in the internal carotid artery. Inputs for cognitive-emotional control from the exteroceptive sense organs (touch, vision, sound, smell, etc.) are integrated in forebrain centers including the amygdala. Psychoactive drugs have major effects on the acral cutaneous circulation. Interoceptors, chemoreceptors more than baroreceptors, also influence cutaneous sympathetic outflow. A major advance has been the discovery of a lower brainstem control center in the rostral medullary raphé, regulating outflow to both brown adipose tissue (BAT) and to the acral cutaneous beds. Neurons in the medullary raphé, via their descending axonal projections, increase the discharge of spinal sympathetic preganglionic neurons controlling the cutaneous vasculature, utilizing glutamate, and serotonin as neurotransmitters. Present evidence suggests that both thermoregulatory and cognitive-emotional control of the cutaneous beds from preoptic, hypothalamic, and forebrain centers is channeled via the medullary raphé. Future studies will no doubt further unravel the details of neurotransmitter pathways connecting these rostral control centers with the medullary raphé, and those operative within the raphé itself. © 2016 American Physiological Society. Compr Physiol 6:1161-1197, 2016. PMID:27347889

  1. Taurolidine and congeners activate hTRPA1 but not hTRPV1 channels and stimulate CGRP release from mouse tracheal sensory nerves.

    Science.gov (United States)

    Kichko, Tatjana I; Pfirrmann, Rolf W; Reeh, Peter W

    2016-02-01

    Taurolidine has long been in clinical use as an antimicrobial irrigation that does not impede wound healing. It can even be administered intravenously (30 g/day) to treat sepsis or to exert newly recognized antineoplastic actions. Only one irritant effect is reported, that is, to temporarily induce burning pain of unknown origin when applied to body cavities or peripheral veins. The structure of the molecule suggested the chemoreceptor channel TRPA1 as a potential target, which was verified measuring stimulated CGRP release from sensory nerves of the isolated mouse trachea and calcium influx in hTRPA1-transfected HEK293 cells. With both methods, the concentration-response relationship of taurolidine exceeded the threshold value below 500 μmol/L and 100 μmol/L, respectively, and reached saturation at 1 mmol/L. The clinical 2% taurolidine solution did not evoke greater or longer lasting responses. The reversible tracheal response was abolished in TRPA1(-/-) but retained in TRPV1(-/-) mice. Consistently, hTRPV1-HEK showed no calcium influx as a response, likewise native HEK293 cells and hTRPA1-HEK deprived of extracellular calcium did not respond to taurolidine 1 mmol/L. The metabolite taurultam and its oxathiazine derivative, expected to cause less burning pain, showed weak tracheal irritancy only at 10 mmol/L, acting also through hTRPA1 but not hTRPV1. In conclusion, taurolidine, its metabolite, and a novel derivative showed no unspecific cellular effects but selectively, concentration-dependently and reversibly activated the irritant receptor TRPA1 in CGRP-expressing, thus nociceptive, neurons. The clinical solution of 2% taurolidine (~70 mmol/L) can, thus, rightly be expected to cause transient burning pain and neurogenic inflammation. PMID:26977296

  2. Increased ventilatory response to carbon dioxide in COPD patients following vitamin C administration

    Directory of Open Access Journals (Sweden)

    Sara E. Hartmann

    2015-09-01

    Full Text Available Patients with chronic obstructive pulmonary disease (COPD have decreased ventilatory and cerebrovascular responses to hypercapnia. Antioxidants increase the ventilatory response to hypercapnia in healthy humans. Cerebral blood flow is an important determinant of carbon dioxide/hydrogen ion concentration at the central chemoreceptors and may be affected by antioxidants. It is unknown whether antioxidants can improve the ventilatory and cerebral blood flow response in individuals in whom these are diminished. Thus, we aimed to determine the effect of vitamin C administration on the ventilatory and cerebrovascular responses to hypercapnia during healthy ageing and in COPD. Using transcranial Doppler ultrasound, we measured the ventilatory and cerebral blood flow responses to hyperoxic hypercapnia before and after an intravenous vitamin C infusion in healthy young (Younger and older (Older subjects and in moderate COPD. Vitamin C increased the ventilatory response in COPD patients (mean (95% CI 1.1 (0.9–1.1 versus 1.5 (1.1–2.0 L·min−1·mmHg−1, p0.05 or Older (1.3 (1.0–1.7 versus 1.3 (1.0–1.7 L·min−1·mmHg−1, p>0.05 healthy subjects. Vitamin C did not affect the cerebral blood flow response in the young or older healthy subjects or COPD subjects (p>0.05. Vitamin C increases the ventilatory but not cerebrovascular response to hyperoxic hypercapnia in patients with moderate COPD.

  3. CO2 decreases membrane conductance and depolarizes neurons in the nucleus tractus solitarii.

    Science.gov (United States)

    Dean, J B; Lawing, W L; Millhorn, D E

    1989-01-01

    To identify central sites of potential CO2/H+-chemoreceptive neurons, and the mechanism responsible for neuronal chemosensitivity, intracellular recordings were made in rat tissue slices in two cardiopulmonary-related regions (i.e., nucleus tractus solitarii, NTS; nucleus ambiguus, AMBc) during exposure to high CO2. When the NTS was explored slices were bisected and the ventral half discarded. Utilizing such "dorsal" medullary slices removed any impinging synaptic input from putative chemoreceptors in the ventrolateral medulla. In the NTS, CO2-induced changes in firing rate were associated with membrane depolarizations ranging from 2-25 mV (n = 15). In some cases increased e.p.s.p. activity was observed during CO2 exposure. The CO2-induced depolarization occurred concomitantly with an increased input resistance ranging from 19-23 M omega (n = 5). The lower membrane conductance during hypercapnia suggests that CO2-induced depolarization is due to a decreased outward potassium conductance. Unlike neurons in the NTS, AMBc neurons were not spontaneously active and were rarely depolarized by hypercapnia. Eleven of 12 cells tested were either hyperpolarized by or insensitive to CO2. Only 1 neuron in the AMBc was depolarized and it also showed an increased input resistance during CO2 exposure. Our findings suggest that CO2/H+-related stimuli decrease potassium conductance which depolarizes the cell and increases firing rate. Although our in vitro studies cannot guarantee the specific function of these cells, we believe they may be involved with brain pH homeostasis and cardiopulmonary regulation. PMID:2507342

  4. A single muscle moves a crustacean limb joint rhythmically by acting against a spring containing resilin

    Directory of Open Access Journals (Sweden)

    Burrows Malcolm

    2009-05-01

    Full Text Available Abstract Background The beating or fanning movements of three pairs of maxilliped flagella in crabs and crayfish modify exhalent gill currents while drawing water over chemoreceptors on the head. They play an integral part both in signalling by distributing urine odours, and in active chemosensation. Results The rhythmical maxilliped movements start with maxilliped 3 followed after a delay of 15 to 20 ms in shore crabs by maxilliped 2 and then maxilliped 1, at a frequency of 18 to 20 Hz in crabs and 10 to 13 Hz in signal crayfish. The contraction of a single abductor muscle controls the power stroke (abduction of each flagellum, which is accompanied by flaring of feather-like setae which increase its surface area. No muscle can bring about the return stroke (adduction. Release of an isolated flagellum from an imposed abduction is followed by a rapid recoil to its resting adducted position. The relationship between the extent of abduction and the angular velocity of the return stroke indicates the operation of a spring. Blue fluorescence under UV light, and its dependence on the pH of the bathing medium, indicates that resilin is present at the joint between an exopodite and flagellum, at the annuli of a flagellum and at the base of the setae. Conclusion Resilin is progressively bent as a flagellum is abducted and resumes its natural shape when the joint recoils. Other distortions of the exopodites may also contribute to this spring-like action. The joint is therefore controlled by a single abductor muscle operating against a spring in which the elastic properties of resilin play a key role.

  5. Do polymorphisms in chemosensory genes matter for human ingestive behavior?

    Science.gov (United States)

    Hayes, John E; Feeney, Emma L; Allen, Alissa L

    2013-12-01

    In the last decade, basic research in chemoreceptor genetics and neurobiology have revolutionized our understanding of individual differences in chemosensation. From an evolutionary perspective, chemosensory variations appear to have arisen in response to different living environments, generally in the avoidance of toxins and to better detect vital food sources. Today, it is often assumed that these differences may drive variable food preferences and choices, with downstream effects on health and wellness. A growing body of evidence indicates chemosensory variation is far more complex than previously believed. However, just because a genetic polymorphism results in altered receptor function in cultured cells or even behavioral phenotypes in the laboratory, this variation may not be sufficient to influence food choice in free living humans. Still, there is ample evidence to indicate allelic variation in TAS2R38 predicts variation in bitterness of synthetic pharmaceuticals (e.g., propylthiouracil) and natural plant compounds (e.g., goitrin), and this variation associates with differential intake of alcohol and vegetables. Further, this is only one of 25 unique bitter taste genes (TAS2Rs) in humans, and emerging evidence suggests other TAS2Rs may also contain polymorphisms that a functional with respect to ingestive behavior. For example, TAS2R16 polymorphisms are linked to the bitterness of naturally occurring plant compounds and alcoholic beverage intake, a TAS2R19 polymorphism predicts differences in quinine bitterness and grapefruit bitterness and liking, and TAS2R31 polymorphisms associate with differential bitterness of plant compounds like aristolochic acid and the sulfonyl amide sweeteners saccharin and acesulfame-K. More critically with respect to food choices, these polymorphisms may vary independently from each other within and across individuals, meaning a monolithic one-size-fits-all approach to bitterness needs to be abandoned. Nor are genetic

  6. Olfactory Responses of the Asiatic Citrus Psyllid (Diaphorina citri to Mineral Oil-Treated Mandarin Leaves

    Directory of Open Access Journals (Sweden)

    Mofit E. Poerwanto

    2012-01-01

    Full Text Available Problem statement: Evidence of rejection or acceptance by phytophagous pests of citrus plants treated with mineral oils suggests that impacts of oils may be related to detection by olfactory and/or contact chemoreceptors of repellent oils or plant volatiles. Alternatively, the oils may mask or suppress attractant host plant volatiles. To date, no studies have reported that oils elicit an olfactory response in Diaphorina citri Kuwayama [Hemiptera: Psyllidae]. Therefore, we undertook two studies to determine how oil deposits on citrus leaves influenced the behaviour of D. citri. Approach: The attractiveness of citrus leaves treated separately with an nC21 horticultural mineral oil and an nC24 agricultural mineral oil to D. citri was evaluated under laboratory conditions. In the first of two studies, the oils were applied as 0.5% aqueous emulsions to mandarin leaves and responses of adults determined after they walked on surfaces saturated with either distilled water or 2% aqueous emulsions of the oils. In the second study, responses of adult psyllids to host-leaf volatiles, mineral oil volatiles emanating from leaves dipped in 2% v/v aqueous emulsions of each oil and similarly treated filter paper paired with water-dipped leaves were determined in single, linear-tube olfactometers. Results: In the first study, deposits of both oils significantly reduced the proportion of D. citri attracted to citrus leaves. Prior exposure of the insects to oil deposits did not influence this response. However, prior contact with the HMO slightly reduced the proportion of psyllids alighting on the water-dipped leaves. In the second study, oil volatiles emanating from filter paper significantly reduced the attractiveness of water-dipped mandarin leaves. Conclusion: These results indicate that application of the oils to the mandarin leaves may have: (a suppressed release of attractant host plant volatiles; (b masked attractant host plant volatiles; (c led to the

  7. The ventilatory responses of conscious dogs to isocapnic oxygen tests. a method of exploring the central component of respiratory drive and its dependence on O2 and CO2.

    Science.gov (United States)

    Ungar, A; Bouverot, P

    1980-02-01

    Conscious unrestrained dogs trained to breathe through a respiratory mask or, after chronic tracheostomy, through a cuffed endotracheal tube were studied in an altitude chamber operated in such a way that end-tidal PO2 was maintained at 100, 75 or 60 Torr. Each hypoxic experiment was completed within 1 h of the onset of hypoxia. At all levels of oxygenation, resting pulmonary ventilation (V), obtained from the tidal volume (VT) and ventilatory period (T), and alveolar gas tensions (PAO2, PACO2) were measured cycle-by-cycle before and during isocapnic O2-tests (IOT) at various steady levels of alveolar PCO2 ranging from 30 to 48 Torr. For this, PCO2 in the inspired gas before and during IOT was adjusted so that PACO2 remained unchanged in the course of the first few breaths which followed the switch to hyperoxia. In analysing the transient changes of V in the course IOT, it was considered that an apnoea occurred when there was no measurable deflection on the integrated pneumotachogram past a duration twice the control T from the beginning of the last recorded ventilatory cycle. (1) Control V vs. PACO2 relationships showed classic positive interaction between hypercapnia and hypoxia; (2) during IOT at PAO2 of 100, 75 or 60 Torr, an apnoea occurred, V invariably falling to zero, provided that PACO2 was below 38-35 Torr according to the level of oxygenation; (3) above that threshold PACO2 value, the residual minimum ventilation (Vres) observed during IOT was linearly related to PACO2; (4) Vres vs. PACO2 relationships showed negative interaction between hypercapnia and hypoxia. It is concluded that (a) through isocapnic O2-tests, both the peripheral and central components of the ventilatory drive can be quantitatively estimated; (b) in conscious dogs, the pulmonary ventilation appears to be entirely driven by afferent activity from the arterial chemoreceptors, even in eucapnic normoxia; (c) the lower minimum ventilation seen in the course of O2-tests from a hypoxic

  8. Do polymorphisms in chemosensory genes matter for human ingestive behavior?

    Science.gov (United States)

    Hayes, John E.; Feeney, Emma L.; Allen, Alissa L.

    2013-01-01

    In the last decade, basic research in chemoreceptor genetics and neurobiology have revolutionized our understanding of individual differences in chemosensation. From an evolutionary perspective, chemosensory variations appear to have arisen in response to different living environments, generally in the avoidance of toxins and to better detect vital food sources. Today, it is often assumed that these differences may drive variable food preferences and choices, with downstream effects on health and wellness. A growing body of evidence indicates chemosensory variation is far more complex than previously believed. However, just because a genetic polymorphism results in altered receptor function in cultured cells or even behavioral phenotypes in the laboratory, this variation may not be sufficient to influence food choice in free living humans. Still, there is ample evidence to indicate allelic variation in TAS2R38 predicts variation in bitterness of synthetic pharmaceuticals (e.g., propylthiouracil) and natural plant compounds (e.g., goitrin), and this variation associates with differential intake of alcohol and vegetables. Further, this is only one of 25 unique bitter taste genes (TAS2Rs) in humans, and emerging evidence suggests other TAS2Rs may also contain polymorphisms that a functional with respect to ingestive behavior. For example, TAS2R16 polymorphisms are linked to the bitterness of naturally occurring plant compounds and alcoholic beverage intake, a TAS2R19 polymorphism predicts differences in quinine bitterness and grapefruit bitterness and liking, and TAS2R31 polymorphisms associate with differential bitterness of plant compounds like aristolochic acid and the sulfonyl amide sweeteners saccharin and acesulfame-K. More critically with respect to food choices, these polymorphisms may vary independently from each other within and across individuals, meaning a monolithic one-size-fits-all approach to bitterness needs to be abandoned. Nor are genetic

  9. Investigation into the characteristics, triggers and mechanism of apnoea and bradycardia in the anaesthetized platypus (Ornithorhynchus anatinus).

    Science.gov (United States)

    Macgregor, J W; Holyoake, C; Fleming, P A; Robertson, I D; Connolly, J H; Warren, K S

    2014-01-01

    Health and conservation research on platypuses (Ornithorhynchus anatinus) may require anaesthesia to reduce stress and the risk of injury to both the animal and the researcher, as well as to facilitate examination and sample collection. Platypus anaesthesia can be difficult to manage, with reports of periods of apnoea and bradycardia described. This study investigated the conditions around sudden-onset apnoea and bradycardia in 163 field-anaesthetized platypuses as part of a health study. Anaesthesia was induced and maintained using isoflurane delivered in oxygen by face mask. Sudden-onset apnoea and bradycardia was observed in 19% of platypuses, occurring either at induction of anaesthesia, during recovery, or both. At induction, occurrence was more often recorded for adults (P = 0.19) and was correlated with low body temperature (P < 0.001), season (P = 0.06; greater incidence in summer) and longer pre-anaesthetic holding time (P = 0.16). At recovery, sudden-onset apnoea and bradycardia occurred only in platypuses that had been placed in dorsal recumbency as part of their examination, and correlated with poor body condition (P = 0.002), time in dorsal recumbency (P = 0.005), adults (P = 0.06), number of fieldworkers (P = 0.06) and females (P = 0.11). The sudden-onset apnoea and bradycardia we observed is likely to result from the irritant nature of isoflurane (stimulating the trigeminal nerve via nasal chemoreceptors). We propose that this mechanism is analogous to that of submersion of the face/nasal cavity in cold water during a natural dive response, but that the term 'nasopharyngeal response' would more appropriately describe the changes observed under isoflurane anaesthesia. Although we did not record any long-term adverse effects on platypuses that had undergone this response, the nasopharyngeal response could complicate the diagnosis of anaesthetic dose-dependent apnoea and bradycardia. Therefore, we suggest that these

  10. Characteristics of renal sympathetic nerve single units in rabbits with angiotensin-induced hypertension.

    Science.gov (United States)

    Burke, Sandra L; Lukoshkova, Elena V; Head, Geoffrey A

    2016-01-01

    We examined the effect of chronic angiotensin (Ang II)-induced hypertension on activity of postganglionic renal sympathetic units to determine whether altered whole renal nerve activity is due to recruitment or changes in firing frequency. Rabbits were treated with a low (20 ng kg(-1) min(-1), 8 weeks) or high dose (50 ng kg(-1) min(-1), 4 weeks) of Ang II before the experiment under chloralose-urethane anaesthesia. Spontaneously active units were detected from multiunit recordings using an algorithm that separated units by action potential shape using templates that matched spikes within a prescribed standard deviation. Multiunit sympathetic nerve activity was 40% higher in rabbits treated with low-dose Ang II than in sham (P = 0.012) but not different in high-dose Ang II. Resting firing frequency was similar in sham rabbits (1.00 ± 0.09 spikes s(-1), n = 144) and in those treated with high-dose Ang II (1.10 ± 0.08 spikes s(-1), n = 112) but was lower with low-dose Ang II (0.65 ± 0.08 spikes s(-1), n = 149, P < 0.05). Unit firing rhythmicity was linked to the cardiac cycle and was similar in sham and low-dose Ang II groups but 29-32% lower in rabbits treated with high-dose Ang II (P < 0.001). Cardiac linkage followed a similar pattern during hypoxia. All units showed baroreceptor dependency. Baroreflex gain and range were reduced and curves shifted to the right in Ang II groups. Firing frequency during hypoxia increased by +39% in low-dose Ang II and +82% in shams, but the greatest increase was in the high-dose Ang II group (+103%, P(dose) = 0.001). Responses to hypercapnia were similar in all groups. Increases in sympathetic outflow in hypertension caused by low-dose chronic Ang II administration are due to recruitment of neurons, but high-dose Ang II increases firing frequency in response to chemoreceptor stimuli independently of the arterial baroreceptors. PMID:26467849

  11. Integrating the theories of Darwin and Bernoulli: maladaptive baroreceptor network dysfunction may explain the pathogenesis of aortic aneurysms.

    Science.gov (United States)

    Conley, Buford R; Doux, John D; Lee, Patrick Y; Bazar, Kimberly A; Daniel, Stephanie M; Yun, Anthony J

    2005-01-01

    networks including chemoreceptors and lymphoid tissues at bifurcating biologic branch-points such as vessels, airways, nerves, lymphatics, and ducts are discussed. Our framework may also provide a new basis for understanding thoracic aneurysm, renovascular dysfunctions, coronary artery disease, carotid artery disease, pulmonary embolism, portal hypertension, venous thrombosis, biliary disease, pancreatic disease, and neurologic disease. Novel treatment paradigms based on drugs or interconnected networks of devices that modulate sensors are envisioned. Improving the interface between sensors and their substrate information by techniques such as minimally traumatic atherectomy or thrombectomy may also restore appropriate sensor function. Lessons learned from bifurcation sensors and their potential maladaptations may generalize to other types of branching systems including botany, civil engineering, and Pitot tube aeronautics. PMID:15922098

  12. A QSAR Study of the Repellency of some Terpenoids to the Bedbug Cimex lectularius L.%萜类臭虫(Cimex lectularius L.)驱避化合物的定量构效关系研究

    Institute of Scientific and Technical Information of China (English)

    宋杰; 王宗德; 韩招久; 陈金珠; 姜志宽; 郑卫青; 商士斌

    2012-01-01

    测定了一系列六元环萜类化合物对臭虫(Cimex lectularius L.)的驱避活性,利用Codessa Pro程序计算了这些化合物的结构描述符,再利用Codessa Pro程序中的最优线性回归方法计算了驱避活性与这些化合物结构描述符之间的定量构效关系.所得到的最优定量构效关系计算模型的R2为0.924,模型所包含的4个参数分别是:FNSA3 fractional PNSA、Min n-n repulsion for bond H-C、YZ Shadow/YZ rectangle、Max electrophilic reactivity index for atom C.通过对模型的分析讨论了臭虫化学感受器与驱避剂之间可能存在的相互作用.%The quantitative structure-activity relationship (QSAR) between the repellency against bedbug,Cimex lectularius L.(Hemiptera:Cimicidae) and the molecular structural descriptors of a series of terpenoid compounds with six-member-ring was correlated by best multilinear regression (BMLR) method.The descriptors and the multilinear regression were all calculated by Codessa Pro.The optimum multilinear model with R2 value of 0.924 and 4 descriptors,i.e.the fractional atomic charge weighted partial megative surface area (FNSA3) fractional the atomic charge weighted partial negative charge molecular surface area (PNSA),Min n-n repulsion for bond H-C,YZ Shadow/YZ rectangle and Max electrophilic reactivity index for atom C was validated and presented.The probable interaction between the chemoreceptor of bedbug and the repellent was also discussed according to the optimum model and its descriptors.

  13. First Results of 3 Year Monitoring of Red Wood Ants' Behavioural Changes and Their Possible Correlation with Earthquake Events

    Science.gov (United States)

    Berberich, Gabriele; Berberich, Martin; Grumpe, Arne; Wöhler, Christian; Schreiber, Ulrich

    2013-04-01

    Short-term earthquake predictions with an advance warning of several hours or days can currently not be performed reliably and remain limited to only a few minutes before the event. Abnormal animal behaviours prior to earthquakes have been reported previously but their detection creates problems in monitoring and reliability. A different situation is encountered for red wood ants (RWA; Formica rufa-group (Hymenoptera: Formicidae). They have stationary nest sites on tectonically active, gas-bearing fault systems. These faults may be potential earthquake areas and are simultaneously information channels deeply reaching into the crust. A particular advantage of monitoring RWA is their high sensitivity to environmental changes. Besides an evolutionarily developed extremely strong temperature sensitivity of 0.25 K, they have chemoreceptors for the detection of CO2 concentrations and a sensitivity for electromagnetic fields. Changes of the electromagnetic field are discussed or short-lived "thermal anomalies" are reported as trigger mechanisms for bioanomalies of impending earthquakes. For 3 years, we have monitored two Red Wood Ant mounds (Formica rufa-group), located at the seismically active Neuwied Basin (Eifel, Germany), 24/7 by high-resolution cameras equipped with a colour and infrared sensor. In the Neuwied Basin, an average of about 100 earthquakes per year with magnitudes up to M 3.9 occur located on different tectonic fault regimes (strike-slip faults and/or normal or thrust faults). The RWA mounds are located on two different fault regimes approximately 30 km apart. First results show that the ants have a well-identifiable standard daily routine. Correlation with local seismic events suggests changes in the ants' behaviour hours before the earthquake event: The nocturnal rest phase and daily activity are suppressed, and standard daily routine is continued not before the next day. Additional parameters that might have an effect on the ants' daily routine

  14. Bases fisiológicas y tratamiento de la emésis inducida por radiaciones

    Directory of Open Access Journals (Sweden)

    Bárbara M. Mulén Nápoles

    2002-10-01

    Full Text Available En el curso del tratamiento oncoespecífico se presentan con frecuencia como complicaciones las náuseas y vómitos. El reflejo emético inducido por radiaciones depende de varios factores: el sitio primario de irradiación, la dosis administrada, el fraccionamiento, el volumen irradiado, y las características sensoriales y psíquicas del paciente, así como la asociación de quimioterapia. Se conoce que la vía aferente al llamado centro del vómito está determinada por mediadores químicos, los receptores protuberanciales de la presión intracraneal y la zona quimiorreceptora desencadenante. En la emésis inducida por radiación, el mecanismo exacto aún está por determinar; se sabe que la radiación estimula la producción de mediadores químicos como la serotonina liberada por las células enterocromafines que actúan sobre el centro del vómito y el núcleo vagal. La mayoría de los pacientes irradiados en hemicuerpo superior y medio, así como la totalidad de los sometidos a irradiación corporal total, presentan náuseas y vómitos. Las recomendaciones terapéuticas antieméticas se fundamentan en el control neuroquímico del vómito así como del efecto emetogénico del tratamiento radiante. Los antagonistas de los receptores de 5HT3 se evalúan como efectivos en el control de la emésis inducida por radiaciones.In the course of the specific oncologic treatment, there are frequent complications such as nausea and vomiting. The radiation-induced emetic reflex depends on various factors: primary site of radiation, administered dose, fractioning, irradiated volume, the sensory and psychic characteristics of the patient as well as the chemotherapy association. It is known that the afferent path to the so-called center of vomiting is determined by chemical mediators, protuberance receptors of the intracranial pressure and the unleashing chemoreceptor zone. In radiation-induced emesis, the exact mechanism is yet to be determined but it is

  15. Single Chain Fv Constructs of Anti-Ganglioside GD2 Antibodies for Radioimaging and Radioimmunotherapy

    International Nuclear Information System (INIS)

    of its broad and usually homogeneous distribution in human solid tumors, and most importantly, their absence on cell membranes of normal human tissues. In separate experiments, we have shown that T-cells transduced with the herpes simplex viral thymidine kinase (HSV-tk) gene can be radiolabeled with 131I-FIAU to a safe nuclear radiation dose. Using a dicistronic construct we are inserting chimeric immune receptor plus HSV-tk into T-cells to allow such their trafficking to be radioactively monitored. We plan to study the role of cytokines, chemoreceptors and CD4 helper T-cells in recruiting CD8+ transduced T-cells to the tumor site. These studies should provide us with an adoptive cell therapy approach to target cytotoxicity to human tumors, and a lymphocyte tracking tool to study delivery to the tumor sites, to determine if they proliferate locally and/or recirculate. Such pharmacologic information is crucial for optimizing gene-modified T-cells in future clinical trials. Single chain FV constructs of anti-ganglioside GD2 antibodies for radioimaging

  16. 不同频率间歇低氧暴露后兔颈动脉体的炎症状态和窦神经传入活性%Carotid body inflammation and carotid sinus nerve afferent activity after intermittent hypoxia exposure of various frequencies in rabbits

    Institute of Scientific and Technical Information of China (English)

    冯靖; 陈宝元; 崔林阳; 王宝利; 刘春霞; 陈攀峰; 郭美南; 董丽霞; 李硕

    2008-01-01

    Objective To explore the inflammatory reactions,endothelin level and carotid sinus nerve(CSN)afferent activity of carotid body(CB)after intermittent hypoxia/reoxygenation(IH/ROX)exposure of various frequencies in rabbits.Methods Forty-nine male adult New Zealand white rabbits (2.5~3.0 kg)were separated into 7 groups(n=7 each).After anesthetization,the fight carotid artery and CSN were cleared of surrounding tissues without touching the right CB and the left carotid region.The CSN was unenveloped to pareally expose the myelin sheath.and electrodes were placed to the"single"chemoreceptor bundle of the CSN.with CSN afferent activity carefully monitored and recorded.Then the right common carotid artery was exposed,cannulated to distal part and its proximal part was ligated.Preparations were challenged by changing the PO2 of the gas mixture equilibrating the perfusate.Alternatively perfusion (2 mL/min) of equilibrated perfusate bubbled with normoxia or hypoxia gas mixtures formed IH/ROX cycles in right carotid common artery,simulating the pattern of hypoxic episodes seen in obstructive sleep apnea,or with continuously perfusing hypoxia perfusate to form continuous hypoxia (CH)modes.Groups were defined with different frequencies,and groups were: intermittent normnxia group (IN group) (21% O2,15 s;21% O2,1 min 45 s),10/hr group (5% O2,15 s ;21% O2,5 rain 45 s),30/hrgroup (5%O2,15 s;21%O2,1 min45 s),50/hr group (5%O2,15 s;21%O2,57 s),60/hr group (5%O2 ,15 s;21%O2,45 s) and 90/hr group (5%O2,15 s;21%O2,25 s).All the above groups were exposed to 60 treatment cycles;continuous hypoxia group (CH group),IN for 1 h 45min and then 5% O2 for 15 min.After exposure and 30 min of static placing,CSN afferent frequencies (Charge F) were recorded from chemoreceptor bundles,and the right CB was cleared of surrounding tissues and harvested.Interleukin-6 (IL-6),endothelin-1 (ET-1),hypoxla-indacible factor-1 (HIF-I),and vascular endothelial growth factor (VEGF) concentrations of the CB

  17. First Results of 3 Year Monitoring of Red Wood Ants' Behavioural Changes and Their Possible Correlation with Earthquake Events

    Science.gov (United States)

    Berberich, Gabriele; Berberich, Martin; Grumpe, Arne; Wöhler, Christian; Schreiber, Ulrich

    2013-04-01

    Short-term earthquake predictions with an advance warning of several hours or days can currently not be performed reliably and remain limited to only a few minutes before the event. Abnormal animal behaviours prior to earthquakes have been reported previously but their detection creates problems in monitoring and reliability. A different situation is encountered for red wood ants (RWA; Formica rufa-group (Hymenoptera: Formicidae). They have stationary nest sites on tectonically active, gas-bearing fault systems. These faults may be potential earthquake areas and are simultaneously information channels deeply reaching into the crust. A particular advantage of monitoring RWA is their high sensitivity to environmental changes. Besides an evolutionarily developed extremely strong temperature sensitivity of 0.25 K, they have chemoreceptors for the detection of CO2 concentrations and a sensitivity for electromagnetic fields. Changes of the electromagnetic field are discussed or short-lived "thermal anomalies" are reported as trigger mechanisms for bioanomalies of impending earthquakes. For 3 years, we have monitored two Red Wood Ant mounds (Formica rufa-group), located at the seismically active Neuwied Basin (Eifel, Germany), 24/7 by high-resolution cameras equipped with a colour and infrared sensor. In the Neuwied Basin, an average of about 100 earthquakes per year with magnitudes up to M 3.9 occur located on different tectonic fault regimes (strike-slip faults and/or normal or thrust faults). The RWA mounds are located on two different fault regimes approximately 30 km apart. First results show that the ants have a well-identifiable standard daily routine. Correlation with local seismic events suggests changes in the ants' behaviour hours before the earthquake event: The nocturnal rest phase and daily activity are suppressed, and standard daily routine is continued not before the next day. Additional parameters that might have an effect on the ants' daily routine