Extracellular multi-unit recording from the olfactory nerve of teleosts

Recent studies have shown that ocean acidification affects olfactory-driven behavior in fish. This may be due in part to a reduction in olfactory sensitivity in high PCO2/low pH water. To assess the effects of ocean acidification, or olfactory sensitivity in marine fish in general, we propose that extracellular multi-unit recording from the olfactory nerve is the method of choice. Although invasive, it is sensitive, robust, reproducible and independent of external salinity (unlike the electro-olfactogram [EOG], for example). Furthermore, it records a primary sensory input into the CNS, prior to any central processing. We show that this method can show a reduction in olfactory sensitivity that is both temporary and odorant-dependent, using a range of amino acids to construct concentration-response curves and calculate the thresholds of detection.FCT: PTDC/BIA-BMA/30262/2017/ DL57/2016/CP1361/CT0041info:eu-repo/semantics/publishedVersio

Ocean acidification affects the expression of neuroplasticity and neuromodulation markers in seabream

A possible explanation for acidification-induced changes in fish behaviour is that acidification interferes with neurogenesis and modifies the plasticity of neuronal circuitry in the brain. We tested the effects on the olfactory system and brain of gilthead seabream (Sparus aurata) to 4 weeks' exposure to ocean acidification (OA). Olfactory epithelium (OE) morphology changed shortly after OA exposure and persisted over the 4 weeks. Expression of genes related to olfactory transduction, neuronal excitability, synaptic plasticity, GABAergic innervation, and cell proliferation were unchanged in the OE and olfactory bulb (OB) after 4 weeks' exposure. Short-term changes in the ionic content of plasma and extradural fluid (EDF) returned to control levels after 4 weeks' exposure, except for [Cl-], which remained elevated. This suggests that, in general, there is an early physiological response to OA and by 4 weeks a new homeostatic status is achieved. However, expression of genes involved in proliferation, differentiation and survival of undifferentiated neurons were modified in the brain. In the same brain areas, expression of thyroid hormone signalling genes was altered suggesting modifications in the thyroid-system may be linked to the changes in neuroplasticity and neurogenesis. Overall, the results of the current study are consistent with and effect of OA on neuroplasticity.Mexican national funds from CONACYT -Consejo Nacional de Ciencia y Tecnologi'a, Mexico 2018-000022-01info:eu-repo/semantics/publishedVersio

Adaptation to reduced salinity affects the olfactory sensitivity of Senegalese sole (Solea senegalensis Kaup 1858) to Ca2+ and Na+ but not amino acids

The Senegalese sole is a marine flatfish, which often penetrates into estuarine waters to feed. It cannot, however, survive in full freshwater. The current study investigated the effect of adaptation to low salinity (10‰) on olfactory responses to changes in environmental [Ca2+] and [Na+] and amino acids by the electro-encephalogram (EEG) recorded from the olfactory bulb. The sole showed olfactory responses to increases in environmental [Na+] and decreases in environmental [Ca2+]; sensitivity to Na+ was greater at 10‰ whereas sensitivity to Ca2+ was greater at 35‰. Decreased environmental [Na+] increased sensitivity to changes in [Ca2+] whereas increased environmental [Ca2+] decreased bulbar responses to changes in [Na+]. Sensitivity to amino acids was unaffected by external salinity. However, the absence of external Na+ strongly decreased bulbar responses to amino acids in fish adapted to 35‰ seawater but not in those at 10‰. The absence of external Ca2+ had no such effect at either salinity. This suggests that odorant-receptor binding and/or olfactory transduction is reliant on external Na+ (but not Ca2+) at higher salinities but the olfactory system is able to adapt to lower environmental [Na+]. Taken together, these results suggest that reductions of external salinity modulate olfactory sensitivity to environmental Ca2+ and Na+ but not amino acids. However, at low salinities, olfactory sensitivity to amino acids is maintained by decreasing reliance on external Na+

Biological characterization of Cynara cardunculus L. Methanolic extracts: antioxidant, anti-proliferative, anti-migratory and anti-angiogenic activities

Cynara cardunculus (Cc) is a multipurpose species; beyond its use in southwestern European cuisine, it is also used for the production of solid biofuel, seed oil, biodiesel, paper pulp and cheese, as well as animal feed. In addition, Cc has a long tradition of use in folk medicine as a diuretic and liver protector. The value of this species as a source of bioactive compounds is known; however, pharmacological use would further increase its cultivation. The main goal of the current work was to evaluate the potential of Cc as source of anti-carcinogenic phytochemicals. Different methanolic extracts obtained from wild and cultivated plants were tested for antioxidant activity and effect on breast tumor cell viability. The most effective extract, both as antioxidant and inhibition of tumor cell viability, was tested for effects on angiogenesis and tumor cell migration capacity. All the extracts tested had high antioxidant activity; however, only green leaves and dry head extracts exhibit anti-proliferative activity. Green cultivated leaves (GCL) were the most effective extract both as antioxidant and inhibiting the proliferation of tumor cells; it is equally active inhibiting tumor cell migration and in vivo angiogenesis. GCL extract is an effective inhibitor of several key points in tumor development and thus a promising source of anti-carcinogenic phytochemicals.info:eu-repo/semantics/publishedVersio

Identification, release and olfactory detection of bile salts in the intestinal fluid of the Senegalese sole (Solea senegalensis)

Olfactory sensitivity to bile salts is wide-spread in teleosts; however, which bile salts are released in suYcient quantities to be detected is unclear. The current study identiWed bile salts in the intestinal and bile Xuids of Solea senegalensis by mass spectrometry–liquid chromatography and assessed their olfactory potency by the electro-olfactogram

An electrical method to measure low-frequency collective and synchronized cell activity using extracellular electrodes

An electrical method to measure extracellular bioelectrical activity in vitro is presented. This method exploits the Helmholtz capacitive double-layer established at the electrode surface. Small extracellular voltage variations in the order of μVs induce through the double-layer capacitor a displacement current that is measured. This current is then enhanced by a gain factor proportional to the electrode capacitance. In addition, when measurements are carried out at low frequencies in current mode the electrode contribution to the noise can be minimized. The performance of the electrodes and the method is demonstrated using zebrafish hearts and glioma cell cultures. We propose that this electrical method is an ideal tool to measure in vitro slow and temporally synchronized events that are often involved in long range intracellular signaling. Keywords: Extracellular electrodes, Bioelectrical signals, Displacement current, Electrical double-layer, Intercellular signalin

Feed Additives for Aquaculture and Aquarium Culture

The presente invention refers of feed additives for aquaculture and aquarium culture. These additives comprise the amino acid, 1-methyl-L-tryptophane, or its isomers with the objective of improving the attractiveness of feeds used in aquaculture and aquaria for fish, as well as other aquatic organisms, under culture conditions. Therefore, this invention has applications in the agriculture-food industry

Neural Mechanisms of olfactory discrimination in the Senegalese sole, Solea senegalensis Kaup, 1858

O ambiente aquático é frequentemente escuro e turvo, tal leva a que muitos peixes e outros organismos não utilizem a visão como principal sentido de orientação. No entanto, este ambiente é geralmente rico em diferentes compostos químicos que se encontram dissolvidos na água, o que faz com que muitos organismos tenham os sentidos químico-sensoriais muito desenvolvidos, especialmente espécies nocturnas e/ou que habitam águas de elevada turbidez. O linguado Senegalês é um peixe bentónico pertencente ao grupo dos peixes chatos (Pleuronectiformes). Tal como a maioria dos peixes deste grupo o linguado passa grande parte do tempo parcialmente enterrado na areia, ficando apenas com os olhos e a narina superior expostos à coluna de água. As principais presas desta espécie são organismos bentónicos que vivem enterrados na areia, tais como poliquetas e crustáceos. Durante a metamorfose, o olho esquerdo migra para o lado superior (direito), no entanto, a narina esquerda não migra permanecendo no lado inferior (esquerdo). Em consequência, os dois epitélios olfactivos do linguado encontram-se expostos a diferentes ambientes; a narina superior amostra a coluna de água, enquanto a narina inferior amostra a água intersticial. Alguns odorantes são detectados de forma diferencial pelos dois epitélios olfactivos, sugerindo a existência de diferenças funcionais no papel que cada uma das narinas desempenha; um fenómeno nunca antes descrito em vertebrados. Esta singularidade faz do linguado um modelo bastante atractivo para o estudo dos mecanismos envolvidos na detecção e descriminação olfactiva. Assim sendo, o principal desafio deste trabalho foi compreender a importância funcional da detecção olfactiva diferencial e alargar o conhecimento referente aos mecanismos de detecção olfactiva no linguado Senegalês. Numa tentativa de estabelecer uma relação entre a diferencial sensibilidade olfactiva e a função dos odorantes envolvidos neste fenómeno, foi feita a identificação química de compostos olfactivamente activos presentes em estímulos relacionados com a detecção e localização de presas e com possíveis interacções intra-específicas. Em adição, foram investigadas as vias de transdução envolvidas na detecção dos compostos identificados. Uma vez que o linguado é frequentemente encontrado em ambientes de salinidade relativamente baixa, foi também avaliada a sensibilidade olfactiva a diferenças nas concentrações de Ca 2+ e Na-', assim como o efeito da salinidade na acuidade olfactiva nesta espécie. Na poliqueta Hediste diversicolor, presa comum do linguado, foram identificados odorantes no seu macerado e na água condicionada por este anelídeo. Ambas as amostras foram fraccionadas por filtração baseada no peso molecular e extracção por fase sólida (colunas C18). A potência olfactiva das fracções resultantes foi avaliada através do electro-olfactograma (EOG). A maioria dos odorantes detectados no macerado são compostos relativamente hidrofilicos de baixo peso molecular (<500Da). Os aminoácidos, em geral, têm estas características químicas e é sabido que os peixes são olfactivamente sensíveis a L-aminoácidos. Perante a possível contribuição de aminoácidos para a potência olfactiva do macerado, o seu conteúdo em aminoácidos foi avaliado por cromatografia gasosa associada a espectrometria de massa (GC-MS). Os aminoácidos mais abundantes no macerado são a glicina e o L-ácido aspártico; a glicina é um estímulo olfactivo forte, no entanto, o linguado é pouco sensível ao L-ácido aspartico. Os restantes aminoácidos mais abundantes são L-histidina, L-prolina, L-alanina e L-asparagina. ### Abstract - Fish face many problems in finding their way around their environment, which is immense, dense, often dark and often devoid of visual cues. Furthermore, the aquatic medium contains many dissolved compounds. Thus, many aquatic animals have acute chemical senses, specially those species with nocturnal activity or habitats with high water turbidity, which can help them navigate and find conspecifics and prey or avoid enemies. The Senegalese sole is a benthic nocturnal flatfish, which typically spends most of its time half-buried in sand with only its eyes and upper nostril exposed to open water, and feeds on benthic organisms, such as crustaceans and polychaetes, which live in the sand. During metamorphosis, the left nostril remains on the left (lower) side of the head, unlike the left eye which migrates to the right side of the head. Therefore, these fish have two olfactory epithelia exposed to two distinct environments; the upper nostril samples open water whilst the lower nostril samples interstitial water. It has been shown that the two olfactory epithelia of sole have different sensitivities to a number of different compounds suggesting that there is a functional difference between the roles that the two nostrils play. This functional asymmetry has never been described before in a vertebrate; this makes the sole a highly attractive model to study the mechanisms involved in olfactory detection and discrimination. Thus, the central challenge of this study was to understand the functional importance of differential detection by the two olfactory epithelia and to further our knowledge of the neuronal mechanisms involved in olfactory perception in the sole. To establish a possible relation between differential olfactory detection and the functional importance of the odorants, odorants related to food search and intra-specific interactions in sole were identified, and the signal transduction pathways involved in the detection of the identified compounds in both olfactory epithelia were investigated. Given that sole often lives in estuaries, where salinity can change rapidly, we also evaluated the olfactory sensitivity to changes in environmental [Na and [Cal and the effects of changes of salinity on olfactory sensitivity. The food stimuli used in chemical identification studies were macerates of the polychaete Hediste diversicolor and water containing compounds released by living worms. Both samples were fractionated by molecular weight filtration followed by C18 solid-phase extraction and the olfactory potency of the resultant fractions was assessed by the electro-olfactogram (EOG). Most of the odorants detected by sole in the ragworm macerate were low molecular weight (<500Da) relatively hydrophilic compounds. Amino acids, in general, have these chemical features and fish are, in general, sensitive to L-amino acids. Thus, the amino acid content of the macerate was analysed by gas chromatography coupled to mass spectrometry (GC-MS). The most abundant amino acids present in the macerate were glycine and L-aspartic acid; although sole is sensitive to glycine, acidic amino acids such as aspartic acid are weak odorants. The next most abundant amino acids were L-histidine, L-proline, L-alanine and L-asparagine. Sole is insensitive to L-histidine and L-proline; however, L-alanine and L-asparagine are potent odorants. To evaluate the relative contribution of amino acids to the olfactory potency of ragworm macerate, the olfactory activity of an artificial mixture of amino acids at the same concentration as measured in the macerate was evaluated. Our results confirmed that, in the macerate, the vast majority of the olfactory potency is likely to be due to the presence of amino acids

Overactivation of calcineurin induced by amyloid-beta and prion proteins

Amyloid-beta protein (A[beta]) and the scrapie isoform of prion protein (PrPSs) have a central role in the pathogenesis of Alzheimer's disease (AD) and prion-related encephalopathies (PRE), respectively. In both disorders, the deposition of these misfolded proteins is accompanied by apoptotic neuronal loss. However, the pathogenesis and molecular basis of A[beta]- and PrPSc-neurotoxic effects are not completely understood. The Ca2+/calmodulin-dependent phosphatase calcineurin (CaN), through the dephosphorylation of the proapoptotic protein BAD, may be the link between Ca2+homeostasis deregulation and apoptotic neuronal death. In this study we used primary cultures of rat brain cortical neurons in order to investigate whether A[beta] and PrP affect CaN activity. We observed that synthetic peptides of A[beta] (A[beta]25-35 and A[beta]1-40) and PrP (PrP106-126) increased CaN activity, but did not affect the levels of this protein phosphatase. Moreover, we found that these peptides reduced the levels of BAD phosphorylated at serine residue 112, and this effect was prevented by the CaN inhibitor FK506. Since dephosphorylated BAD translocates to mitochondria, where it triggers cytochrome c release, we determined the levels of BAD in mitochondrial and cytosolic fractions. The data obtained showed that A[beta]- and PrP-treated neurons had higher levels of BAD in mitochondria than control neurons. This increase in mitochondrial BAD levels was matched by a decrease in cytochrome c. FK506 prevented the alterations of mitochondrial BAD and cytochrome c levels induced by A[beta] and PrP peptides. Taken together the data suggest that A[beta] and PrP increased CaN activity, inducing BAD dephosphorylation and translocation to mitochondria and, subsequently, cytochrome c release that may trigger an apoptotic cascade. Therefore, therapeutic strategies targeting CaN might be valuable for these neurodegenerative disorders.http://www.sciencedirect.com/science/article/B6T0B-4RKTN61-1/1/eb0e78c76531a7ec3f56df4935ad1eb

GABA receptors in the olfactory epithelium of the gilthead seabream (Sparus aurata)

Exposure to high PCO2/low pH seawater induces behavioural alterations in fish; a possible explanation for this is a reversal of Cl-/HCO3- currents through GABAA receptors (the GABAA receptor theory). However, the main evidence for this is that gabazine, a GABAA receptor antagonist, reverses these effects when applied to the water, assuming that exposure to systems other than the CNS would be without effect. Here, we show the expression of both metabotropic and ionotropic GABA receptors, and the presence of GABAA receptor protein, in the olfactory epithelium of gilthead seabream. Furthermore, exposure of the olfactory epithelium to muscimol (a specific GABAA receptor agonist) increases or decreases the apparent olfactory sensitivity to some odorants. Thus, although the exact function of GABAA receptors in the olfactory epithelium is not yet clear, this may complicate the interpretation of studies wherein water-borne gabazine is used to reverse the effects of high CO2 levels on olfactory-driven behaviour in fish.info:eu-repo/semantics/publishedVersio