bluuebunny/crossref_metadata_2025_split huggingface dataset:
Retention of furunculosis vaccine components in Atlantic salmon, Salmo salar L., following different routes of vaccine administration
Authors: Press C McL , Evensen Ø , Reitan L J , Landsverk T 
Published: April 2006

AbstractThe retention of vaccine components was studied in Atlantic salmon, Salmo salar L., following different routes of vaccination against Aeromonas salmonicida. Frozen tissue was collected from the spleen, head kidney, hind gut and liver of fish that had been vaccinated by intraperitoneal injection (monovalent and trivalent vaccines), immersion and oral administration 2,6,8 and 16 weeks previously. The trivalent injection group showed the highest levels of specific antibodies and was the only group to show protection following challenge with virulent A. salmonicida. Following intraperitoneal injection, there was an initial widespread distribution of Aeromonas lipo‐polysaccharide, but by 16 weeks lipopolysaccharide was predominantly found in macrophage populations in the spleen, head kidney and abdominal granulomas. Only small amounts of lipopolysaccharide were retained in the head kidney of the immersion group and no lipopolysaccharide was retained in the oral group. Small and inconsistent amounts of A‐layer protein were present in the meianomacrophages of the head kidney of all groups. The relative prominence of A‐layer protein in the spleen of the trivalent injection group 8 weeks after vaccination was linked to the high levels of specific antibodies, and possible immune‐complex trapping and the enhancement of immunological memory.
Is the turbot, Scophthalmus maximus (L.), intestine a portal of entry for the fish pathogen Vibrio anguillarum?
Authors: Oisson J C , Jöborn A , Westerdahl A , Blomberg L , Kjelleberg S , Conway P L 
Published: April 2006

AbstractThe role of the intestinal tract in Vibrio anguillarum infection of turbot, Scophthalmus maximus (L.), fingerlings was investigated in two in vivo models and the possible mechanisms involved were studied in vitro. Viable V. anguillarum cells were detected in spleens from more than 50% of the fish administered the pathogen orally or rectally, suggesting that the intestinal tract is a portal of entry for V anguillarum. In transmission electron micrographs, V. anguillarum‐ like cells were seen close to the rectal epithelium, suggesting penetration of the mucus layer, but no epithelial cell penetration or endocytosis was evident. Attachment to intact turbot intestines was investigated, and 80% or more of the bacterial cells still remained attached after serial washings. A significantly higher number of cells attached to rectal segments than to the other intestinal segments. In vitro, V. anguillarum cells did not adhere specifically to intestinal mucus, but rather accumulated close to intestinal mucus interfaces and subsequently penetrated them. It is proposed that the intestinal ttact of tutbot is a portal of entry for V. anguillarum and that the cells penetrate the intestinal mucus overlaying the epithelial cells.
The effects of microcystins on the serum biochemistry of carp, Cyprinus carpio L., when the toxins are administered by gavage, immersion and intraperitoneal routes
Authors: Carbis C R , Mitchell G F , Anderson J W , McCauley I 
Published: April 2006

AbstractMicrocystins were administered to carp, Cyprinus carpio L., by intraperitoneal injection. Tests performed on the serum indicated liver and gill damage, and disturbances in hepatic and osmoregulatory functions. Exposure of carp to microcystins by gavage and inrimersion caused changes indicating mild liver damage and changes in the equilibrium of cationanion balance in some treatments. The results of gavage and immersion exposure indicate that acute roxicity is unlikely to occur in wild carp populations, but chronic poisoning may follow repeated sublethal exposure. A serum biochemical profile comprising alanine amino transferase, aspartate amino transferase, bile acids, bilirubin, sodium and chloride determinations may provide a useful diagnostic indication of microcystin poisoning in wild carp populations.
Morphological changes in carp epithelial cells infected with Aeromonas hydrophila
Authors: Leung K Y , Lim T M , Lam T J , Sin Y M 
Published: April 2006

AbstractThe in vitro interaction of Aeromonas hydrophila with epithehoma papillosum cells of carp (EPC) was studied. All the virulent and type strains invaded and multiplied inside EPC cells. Morphological changes were induced by the virulent and type strains during the processes of invasion and intracellular replication. Among the virulent group, strain PPD134/91 required the shortest time (30 min post‐infection) to induce cytopathic effects in the EPC monolayers. The EPC cells infected with PPD 134/91 became retracted and condensed, lost their attachment abilities, and eventually disintegrated. Confocal microscopy revealed that tubular structures measuring 0.77 ± 0.19 μm appeared to connect the retracted EPC cells. The cytopathic effect was attributed to the growing and metabolically active bacteria. Avirulent strains such as L37 did not multiply nor induce cytopathic effects in the EPC monolayers.
Genogrouping of birnaviruses isolated from marine fish: a comparison of VP2/NS junction regions on genome segment A
Authors: Hosono N , Suzuki S , Kusuda R 
Published: April 2006

AbstractYellowtail ascites virus and related strains isolated from marine fish have been shown to be similar to infectious necrosis virus (IPNV) in terms of biological and serological characteristics. This paper explores the relationship of aquatic birnaviruses at the genetic level. The junction region on the genome segment A coding viral capsid protein VP2 and viral protease NS was amplified by PCR in six marine strains. Analysis of nucleotide and the deduced amino acid sequences revealed that the six marine strains have amino acid variations in the possible amino terminus of NS when compared to IPNV. The six marine strains form a new genogroup which is distinguished from three serotypes ofPNV.
Neonatal Section of the Optic Chiasm Changes the Interhemispheric Transfer of Visual Information in Cats
Authors: Bisti Silvia , Biral Giampaolo , Trimarchi Carmela 
Published: April 2006

AbstractRecent studies in adult split‐chiasm cats show that the contrast gain of the visual callosal pathway is considerably lower than the gain of the direct geniculocortical system and that high spatial and temporal frequencies are strongly attenuated in the process of callosal transfer. We recorded visual evoked potentials (VEPs) and single unit activities from visual cortical areas 17 and 18 in cats which had the optic chiasm sectioned at 3 weeks of age. Our results show that, unlike the animals sectioned as adults, the contrast gain and the spatial and temporal acuities of the callosal pathway of young split‐chiasm cats were as good as the direct retinogeniculocortical pathway. Thus, under the present experimental conditions all the spatial and temporal information processed in areas 17 and 18 of one hemicortex is transferred to the other hemicortex via the callosal connections. These animals have also been tested behaviourally for the interocular (interhemispheric) transfer of learning of patterns of high spatial frequency and low contrast. In agreement with the electrophysiological results, we find a complete interocular transfer for this behavioural task. We conclude that the functional development of the interhemispheric connections can be modified by an early section of the optic chiasm and therefore the loss in binocular convergence can be partially compensated.
Ultrastructural Double‐Labelling Study of Dopamine Terminals and GABA‐Containing Neurons in Rat Anteromedial Cerebral Cortex
Authors: Verney C. , Alvarez C. , Geffard M. , Berger B. 
Published: April 2006

AbstractThe aim of this study was to identify, at the ultrastructural level, the neuronal targets of dopamine afferents to the medial prefrontal and the anterior cingulate cortex of the adult rat. Since, in addition to pyramidal neurons, the cortical neuronal population mainly consists of GABAergic nonpyramidal intrinsic neurons, the simultaneous visualization of both dopamine‐ and GABA‐containing neurons should leave the pyramidal neurons as the only unlabelled dopamine postsynaptic target. In this context, we used a double labelling immunocytochemical procedure: a pre‐embedding PAP immunostaining to visualize monoclonal conjugated‐dopamine (DA) antibody, followed by postembedding immunogold staining with a polyclonal conjugated‐GABA antibody. In a single section sampling of 369 DA‐immunoreactive (DA‐IR) varicosities observed and the GABA‐containing elements, 75% of the DA‐IR terminals showed no indication of any contact with a GABA neuron. Twenty‐five per cent were found in nonsynaptic contiguity with a GABA‐immunoreactive neuronal element: axon, dendrite or cell body. When a DA varicosity was in nonsynaptic contiguity with a neuronal perikaryon (5% of cases), this cell was GABA positive. Ten per cent of the DA varicosities were contiguous to a GABA axon, but axoaxonic synapses in either direction were never observed. A symmetrical synapse between a DA varicosity and a GABA‐containing dendrite was observed only once. The other 13 DA‐IR terminals exhibiting a clear synaptic junction were apposed to nonGABA‐containing dendrites, spines and shafts. Triads were observed in which a DA varicosity, forming or not a symmetrical synapse, was apposed to an unlabelled dendrite already receiving a symmetrical junction from another unlabelled axon. These data confirm and extend previous results designating the pyramidal cell dendritic tree as the main synaptic target of DA cortical afferents in rat and primate cerebral cortex. However, a direct effect of dopamine on a subpopulation of intrinsic GABA neurons cannot be excluded.
Evidence for the Involvement of Rat Olfactory Bulb in Processes Supporting Long‐Term Olfactory Memory
Authors: Mouly A. M. , Gervais R. , Holley A. 
Published: April 2006

AbstractCurrent advances in the neurobiology of learning and memory suggest the existence of experience‐induced plasticity in sensorial pathways conveying relevant information to higher integrative brain structures. For instance, olfactory learning is known to induce long‐lasting modifications of neural activity at the level of the first relay structure of the olfactory system, the olfactory bulb. The observed forms of plasticity depend on the action exerted during learning by ascending neuromodulatory systems, such as the noradrenergic (NA) system originating from the locus ceruleus. This study was aimed at investigating the importance of olfactory bulb plasticity in learning and retention of an olfactory task. In a daily training schedule animals had to learn to use multi‐site electrical stimulation patterns of the olfactory bulb as discriminative cues for choosing between a palatable and a nonpalatable solution. We first examined the effects of a continuous intrabulbar infusion of propranolol (a β‐NA receptor antagonist) carried out during the learning period. We found that this treatment neither impaired the retention of a previously learned task nor the learning of a new task. However, the animals presented a severe deficit in long‐term retention (>5 days) of the task learned under perfusion. Unexpectedly, this effect cannot be ascribed to a selective blockade of β‐NA receptors since infusion of the drug vehicle (saline‐ascorbate) produced exactly the same deficit while a saline solution remained without effect. A final experiment showed that the selective deficit in long‐term retention was not observed when the infusion of the saline‐ascorbate solution started on the day following completion of learning. Taken together, these results suggest that ascorbate‐sensitive neural processes occurring within the olfactory bulb during learning are of functional importance for long‐term storage of olfactory information.
Ibotenate Lesions of Hippocampus and/or Subiculum: Dissociating Components of Allocentric Spatial Learning
Authors: Morris R. G. M. , Schenk F. , Tweedie F. , Jarrard L. E. 
Published: April 2006

AbstractThis study examined the effects of ibotenic acid‐induced lesions of the hippocampus, subiculum and hippocampus ± subiculum upon the capacity of rats to learn and perform a series of allocentric spatial learning tasks in an open‐field water maze. The lesions were made by infusing small volumes of the neurotoxin at a total of 26 (hippocampus) or 20 (subiculum) sites intended to achieve complete target cell loss but minimal extratarget damage. The regional extent and axon‐sparing nature of these lesions was evaluated using both cresyl violet and Fink – Heimer stained sections. The behavioural findings indicated that both the hippocampus and subiculum lesions caused impairment to the initial postoperative acquisition of place navigation but did not prevent eventual learning to levels of performance almost as effective as those of controls. However, overtraining of the hippocampus + subiculum lesioned rats did not result in significant place learning. Qualitative observations of the paths taken to find a hidden escape platform indicated that different strategies were deployed by hippocampal and subiculum lesioned groups. Subsequent training on a delayed matching to place task revealed a deficit in all lesioned groups across a range of sample choice intervals, but the subiculum lesioned group was less impaired than the group with the hippocampal lesion. Finally, unoperated control rats given both the initial training and overtraining were later given either a hippocampal lesion or sham surgery. The hippocampal lesioned rats were impaired during a subsequent retention/relearning phase. Together, these findings suggest that total hippocampal cell loss may cause a dual deficit: a slower rate of place learning and a separate navigational impairment. The prospect of unravelling dissociable components of allocentric spatial learning is discussed.
Molecular Cloning of Forebrain mRNAs which are Modulated by Sleep Deprivation
Authors: Rhyner Thomas A. , Borbély Alexander A. , Mallet Jacques 
Published: April 2006

AbstractSleep deprivation (SD) experiments have suggested that specific endogenous substances mediate the control of sleep and waking. However, such ‘sleep substances’ have not yet been unambiguously identified. The isolation of specific molecular markers would make it possible to obtain new insights into the regulatory mechanisms underlying sleep and waking. For this purpose, we have used a molecular genetical approach based on subtractive cDNA cloning. Using these techniques, we were able to detect and isolate in rat forebrain four cDNA clones whose corresponding transcripts are expressed at a lower level after 24 h of SD, and six cDNA clones whose corresponding transcripts are expressed at a higher level. For two of the former transcripts, the level showed a significant reduction of approximately 50% after 24 h of SD and a non‐significant reduction after 12 h of SD. A significant reduction was also observed after 12 h of cold exposure. A regional analysis of their level under baseline conditions revealed variation during the 24‐h cycle. The highest levels tended to occur at the onset of darkness, the beginning of the rat's activity period. Our results are compatible with the hypothesis that the cloned transcripts are associated with the regulation of the sleep‐waking cycle. Analysis of their primary structure indicated that these mRNAs have not yet been characterized. The in vivo distribution of these transcripts in the forebrain shows some correspondence to that of receptors of excitatory amino acids, suggesting an association between the functional role of the cloned sequences and this neurotransmission system.
Spontaneous Saccades and Gaze‐Holding Ability in the Pigmented Rat. II. Effects of Localized Cerebellar Lesions
Authors: Chelazzi L. , Ghirardi M. , Rossi F. , Strata P. , Tempia F. 
Published: April 2006

AbstractWe have studied the effects of the ablation of the cerebellar vermal area corresponding to lobules VI – VIII and of the flocculus – paraflocculus of both sides on the spontaneous eye movements performed in the light and in the dark in head‐restrained pigmented rats. These effects have been compared with those already described for the inferior olive lesion. The cerebellar lesions were performed 1 week to 6 months in advance. Eye movements were recorded through a phase detection search coil apparatus. Following vermal topectomy, the main characteristics of the spontaneous saccades are unmodified. Following the ablation of the flocculus – paraflocculus there is no change in the saccadic main sequence. However, the spontaneous saccades in the dark present a postsaccadic drift made up of two components with different time courses, the first one being fast and the second one slow. The former is due in part to a mismatch between the phasic (the pulse) and the tonic (the step) components of the eye movements; the latter to the leakage of the neural integrator. In light only the first component is present and the eye maintains a steady position. The time constant of the neural integrator is considerably reduced to ∼600–900 ms from a value of ∼1600–4000 ms in the intact rats. The amplitude of the postsaccadic drift in the light depends on both the mismatch between the pulse and the step of innervation of the extraocular muscles and the increased leakiness of the neural integrator. The gain of the pulse to step transformation is reduced to ∼0.79 at all saccadic amplitudes and eccentricities and such a reduction is due to a decreased step amplitude, while the pulse amplitude remains unchanged. The contribution of the leakage of the neural integrator to the postsaccadic drift in the light is a function of the eccentricity with a slope of 0.23. The deficits described after flocculus–paraflocculus ablation are also very similar to those described following inferior olive lesion from a quantitative point of view. The possible mechanisms of the visually activated olivocerebellar system in the control of saccadic performance and in maintaining its calibration are discussed.
Both Astrocytes and Neurons Contribute to the Potentiation Mediated by α1‐Adrenoceptors of the β‐Adrenergic‐Stimulated Cyclic AMP Production in Brain
Authors: Marin P. , Delumeau J. C. , Cordier J. , Glowinski J. , Premont J. 
Published: April 2006

AbstractUsing primary neuronal or astrocyte cultures from the striatum of the embryonic mouse, we have observed that the β‐adrenergic agonist isoprenaline (10−5 M) induced a more pronounced accumulation of cAMP in astrocytes than in neurons. In both cell types, the α‐adrenergic selective agonist methoxamine (10−4 M), which alone did not affect the production of cAMP, potentiated the isoprenaline‐evoked response. In support of these observations, when associated α2‐noradrenergic and D1‐dopaminergic responses were prevented, the mixed α1‐ and β‐adrenergic agonist noradrenaline (10−5 M) induced a production of cAMP which was totally blocked by propranolol (10−6 M) and partially abolished by prazosin (10−6 M). Since experiments were made in the presence of 3‐isobutyl‐1‐methylxanthine (1 mM), the observed effects on cAMP accumulation were not related to a modulation of phosphodiesterase activities. In addition, both in astrocytes and in neurons, the potentiation by α1‐adrenergic agonists of the β‐adrenergic‐evoked response required external calcium. Using INDO 1 as a fluorescent probe, methoxamine (25 μM) was shown to induce in astrocytes an increase in cytosolic calcium concentration which was prolonged by isoprenaline (10−5 M) only in the presence of external calcium. These results suggest that the prolonged increase in cytosolic calcium concentration linked to the activation of α1‐ and β‐adrenergic receptors is responsible for the potentiation of the β‐adrenergic‐induced production of cAMP, which is partially dependent on external calcium.
Calbindin D‐28k Protein and mRNA Localization in the Rat Brain
Authors: Séquier J. M. , Hunziker W. , Andressen C. , Celio M. R. 
Published: April 2006

AbstractAfter the discovery of calretinin, a protein with high sequence homology to calbindin D‐28k, the validity of immunohistochemical results obtained using polyclonal antibodies for this protein, was in question. In order to validate the previous results on the localization of calbindin D‐28k in the brain, we localized the protein by highly specific monoclonal antibodies and revealed its mRNA histochemically by in situ hybridization. In general there was good agreement between the results obtained using these two different techniques and those reported in previous publications. The concordance was particularly impressive for the cerebral cortex, basal ganglia, basal nucleus of Meynert, hippocampus, thalamus, cerebellum and superior colliculus. In the amygdala and hypothalamus the low spatial resolution of in situ hybridization did not allow precise definition of some nuclei displaying a positive reaction for the protein. In the rhombencephalon, cells of the parabrachial nuclei and the dorsal raphe nucleus expressed calbindin D‐28k. Neurons in the dorsal horn of the spinal cord and some horizontal cells of the retina were tagged with both methods. The only discrepancy was the presence of immunoreactive ependymal cells, whereas mRNA never occurred in cells lining the ventricles. Thus, the combined approach has established the widespread distribution of cells expressing calbindin D‐28k in the rat brain.
Some Actions of 9‐Amino‐1,2,3,4‐Tetrahydroacridine (THA) on Cholinergic Transmission and Membrane Currents in Rat Sympathetic Ganglia
Authors: Marsh S. J. , Hubbard A. , Brown D. A. 
Published: April 2006

AbstractTHA (Tacrine) is an anticholinesterase drug reported to alleviate cognitive deficit in Alzheimer's disease. We have used rat isolated superior cervical sympathetic ganglia as a model mammalian cholinergic neural system to study effects of THA on cholinergic synaptic transmission and postsynaptic membrane currents. At 0.1 −3 μM, THA augmented the postsynaptic depolarizations and inward clamp currents produced by acetylcholine but not by the cholinesterase‐resistant analogue, DMPP. Higher concentrations depressed these responses to both acetylcholine and DMPP, and reduced the acetylcholine‐induced increase in membrane current noise. At 1 μM, THA did not affect the amplitude or time‐course of fast (nicotinic) excitatory postsynaptic currents (epscs) evoked by single orthodromic volleys, but higher concentrations induced a biphasic epsc decay. In contrast, low concentrations of THA (1–3 μM) greatly augmented and prolonged the muscarinic slow epsc evoked by repetitive orthodromic volleys: this effect was blocked by 1 μM atropine. Concentrations above 0.1 mM produced a membrane depolarization and inhibited a variety of membrane ionic currents, including voltage‐gated Ca current and subsequent Ca‐activated K currents, and voltage‐gated M‐ and A‐type K currents. It is concluded that the principal effect of THA is to inhibit cholinesterase, and that the main consequence of this is to augment and prolong the muscarinic slow epsc. In contrast, the nicotinic fast epsc is not increased but instead may be reduced through a nicotinic channel‐blocking action. Although THA could also block several other ion channels the concentrations required were too high to contribute significantly to its principal pharmacological actions on ganglionic transmission.