Enhancement of learning processes following an acute modafinil injection in mice.

Modafinil is a wakeness-promoting drug, which is effective in the treatment of narcolepsy; its effects on learning processes are however little studied. Thus, the present study was aimed at determining the effects of an acute modafinil injection on a serial reversal discrimination task performed in a T-maze in mice. Independent groups of mice varying by the level of pretest training (either 1 or 4 days of training) were used.

Behavioral and paired-pulse facilitation analyses of long-lasting depression at excitatory synapses in the medial prefrontal cortex in mice.

Accumulative evidence indicates that acute (before extinction) and long-lasting (during extinction) depression can occur at excitatory synapses in mouse medial prefrontal cortex (mPFC) during re-exposure to a tone (conditioned stimulus: CS), previously paired with footshock (unconditioned stimulus: US). As recently shown, the long-term depression (LTD)-like plasticity in the mPFC does not interfere with extinction of CS-evoked freezing but predicts spontaneous recovery of this fear response. Here, the objectives were to investigate: (i).

Microcosm tributyltin bioaccumulation and multibiomarker assessment in the blue mussel Mytilus edulis.

Blue mussels, Mytilus edulis, were exposed to two different concentrations of tributyltin (TBT) in seawater, 1,000 ng Sn/L (C1 experiment) and 10 ng Sn/L (C2 experiment), for 4 d, in order to evaluate the bioaccumulation of TBT by mussels Mytilus edulis in microcosms and to test the ability of a multimarkers analysis to determine the effects of TBT on the biochemical parameters in mussels. Tissue burdens of Mytilus edulis were 204 +/- 7 and 2,120 +/- 4 ng Sn/g TBT after the 4-d tests for the C2 and C1 experiments, respectively. Analyses of dissected organs and/or tissues demonstrated that TBT accumulated to the greatest extent in gills in the C1 experiment and in the digestive gland in the C2 experiment.

Vitamin A deficiency and relational memory deficit in adult mice: relationships with changes in brain retinoid signalling.

Vitamin A and its derivatives, the retinoids, have recently been reported to be implicated in the synaptic plasticity of the hippocampus and in cognitive functions. Acting via transcription factors, retinoids can regulate gene expression via their nuclear receptors [retinoic acid receptors (RARs) and retinoid X receptors (RXRs)]. We recently showed that a moderate (about 30%) hypoexpression of brain (and hippocampal) retinoid signalling, like that naturally occurring in the aged brain of mice, might be related to a selective relational memory deficit.

Copper-free, recoverable dendritic Pd catalysts for the Sonogashira reaction.

Three generations of bidentate phosphinated Pd(II) dendrimers are efficient catalysts in the absence of copper co-catalyst for the Sonogashira reaction and are, with two cyclohexyl substituents on the phosphorus atoms, recovered by precipitation and re-used.

Role of central cholinergic receptor sub-types in spatial working memory: a five-arm maze task in mice provides evidence for a functional role of nicotinic receptors in mediating trace access processes.

A delayed-matching spatial working memory protocol in a 5-arm maze was used to test the hypothesis of differential roles for central nicotinic and muscarinic cholinergic receptors in mediating task performance. In experiment 1, using a within subjects-repeated design, groups of C57Bl/6 mice, previously trained to criterion with a 4 h retention interval separating presentation and test phases, received i.p.

Involvement of fibroblast growth factors in choroidal angiogenesis and retinal vascularization.

Fibroblast growth factors such as FGF-2 are potent mitogens for endothelial cells and induce their assembly into vascular-like structures in culture and in in vivo assays. However, their putative functions during physiological vascularization are poorly documented. In this study, the eye was used as a model for analyzing the vascular defects caused by targeted FGF inhibition in transgenic mice.

Structure and inhibitory effects on angiogenesis and tumor development of a new vascular endothelial growth inhibitor.

Blocking angiogenesis is an attractive strategy to inhibit tumor growth, invasion, and metastasis. We describe here the structure and the biological action of a new cyclic peptide derived from vascular endothelial growth factor (VEGF). This 17-amino acid molecule designated cyclopeptidic vascular endothelial growth inhibitor (cyclo-VEGI, CBO-P11) encompasses residues 79-93 of VEGF which are involved in the interaction with VEGF receptor-2.

Protective effect of 5-HT1B receptor gene deletion on the age-related decline in spatial learning abilities in mice.

We previously observed that 5 months old serotonin 1B receptor knockout (5-HT1BKO) mice exhibited a facilitation of learning in a long-term spatial memory task in a water maze. In this study, we attempted to assess whether this effect might persist during aging. We compared the performances of young-adult (3 months old) and aged (22 months old) 5-HT1BKO and wild type (WT) mice in the same task.

Assessment of the bioavailability and toxicity of sediment-associated polycyclic aromatic hydrocarbons and heavy metals applied to Crassostrea gigas embryos and larvae.

Sediments represent a vast sink for contaminants in aquatic systems, and may pose a threat to pelagic and benthic organisms. The objective of this research was to determine the bioavailability and toxicity of sediment-associated PAHs and heavy metals, using embryos and larvae of the oyster Crassostrea gigas, exposed to two sediment fractions: the whole sediment and the elutriate. The percentages of abnormal larvae, the contaminant accumulation and, (in the case of metal contamination), the induction of metallothionein in the larvae, were investigated.

Hippocampal lesions and discrimination performance of mice in the radial maze: sparing or impairment depending on the representational demands of the task.

The effects of ibotenate hippocampal lesions on discrimination performance in an eight-arm radial maze were investigated in mice, using a three-stage paradigm in which the only parameter that varied among stages was the way the arms were presented. In the initial learning phase (stage 1), animals learned the valence or reward contingency associated with six (three positive and three negative) adjacent arms of the maze using a successive (go/no-go) discrimination procedure. In the first test phase (stage 2), the six arms were grouped into three pairs, so that on each trial, the subject was faced with a choice between two adjacent arms of opposite valence (concurrent two-choice discrimination).

Spatial learning induces differential changes in calcium/calmodulin-stimulated (ACI) and calcium-insensitive (ACII) adenylyl cyclases in the mouse hippocampus.

Several lines of evidence indicate that Ca2+/calmodulin-stimulated isoforms of adenylyl cyclase (AC) are involved in long-term potentiation and in certain forms of learning. Recently, we found that training in different types of learning task differentially activates Ca2+-sensitive versus Ca2+-insensitive AC activities in certain brain regions, indicating that AC species other than those stimulated by Ca2+/calmodulin may play an important role in learning processes (Guillou, Rose, & Cooper, 1999). Here, we report the effects of spatial reference memory training in a radial arm maze on the levels of AC1 and AC2 mRNA in the dorsal hippocampus of C57BL/6 mice.

Chronic ethanol consumption restores the age-related decrease in neurogranin mRNA level in the hippocampus of mice.

Neurogranin (Ng) is a Ca(2+)-sensitive calmodulin-binding neuron-specific protein that has been implicated in the regulation of numerous post-synaptic signalling pathways. Here, we investigate the effects of 5 months low level ethanol consumption (approximately 20% of total calories intake) on Ng mRNA expression in the brain of adult (approximately 7-8 months) and aged (approximately 21-22 months) mice using in situ hybridization histochemistry. Results showed that ageing was accompanied by a decrease in amounts of mRNA coding for Ng, especially in the hippocampus (approximately 25% of adults) known to play a critical role in higher cognitive functions.

Serotonin 1B knockout mice exhibit a task-dependent selective learning facilitation.

Serotonin 1B knockout (KO) mice exhibit better spatial reference memory performance in the Morris water maze than their wild type (WT) controls. The present study was aimed at dissecting the underlying cognitive bases of this facilitation using a stepwise water maze paradigm. The performance of KO mice did not differ from WT in a single start-goal task, nor when using two opposite starts.

The effects of elutriates from PAH and heavy metal polluted sediments on Crassostrea gigas (Thunberg) embryogenesis, larval growth and bio-accumulation by the larvae of pollutants from sedimentary origin.

The release, bio-availability and toxicity of contaminants, when sediments are resuspended have been examined, studying concurrently their effects on the embryogenesis and on the larval growth of the Crassostrea gigas larvae and their bio-accumulation in those organisms. Three characteristic sediments have been selected (one contaminated by PAHs, a second by heavy metals and the last by the both pollutants). The organisms were directly exposed to elutriates obtained from each sediment or fed on algae (Isochrysis galbana) contaminated with the same elutriates.

Stereoselective intermolecular carboazidation of chiral allylsilanes.

[reaction: see text] Easily available chiral allylsilanes were used as substrate for carboazidation reactions. For the first time, a substantial control of the stereochemistry of the azidation of acyclic nonconjugated radicals was achieved.

Grafting of synthetic mannose receptor-ligands onto onion vectors for human dendritic cells targeting.

A practical preparation of onion vesicles targeted to dendritic cells involves the grafting of mannose-mimetic clusters, bearing a hydrazino group, onto the surface of onion vesicles containing an aldehyde functionalized lipid.

Differential learning abilities of 129T2/Sv and C57BL/6J mice as assessed in three water maze protocols.

Knockout mice are generated by using ES cells from 129 mouse strains and are frequently backcrossed with other strains, like C57BL/6. It is important to characterise the physiological and, in particular, the behavioural profile of each strain in order to correctly analyse the functional contribution of a single gene mutation on the 'cognitive' phenotype. The present study compared 129T2/Sv (129) and C57BL/6J (C57) mice in three different spatial learning protocols in the water maze, using a hidden platform.

Subcellular mass determination by 4He+ energy-loss micro-spectrometry.

The scanning transmission ion microscope (STIM) has been used to determine the intracellular mass of human cultured cells. A 4He+ microbeam of 2.0 MeV energy was chosen to obtain enhanced ion-energy-loss sensitivity through the micron-thick freeze-dried cells.

Efferent controls in crustacean mechanoreceptors.

Since the 1960s it has been known that central neural networks can elaborate motor patterns in the absence of any sensory feedback. However, sensory and neuromodulatory inputs allow the animal to adapt the motor command to the actual mechanical configuration or changing needs. Many studies in invertebrates, particularly in crustacea, have described several mechanisms of sensory-motor integration and have shown that part of this integration was supported by the efferent control of the mechanosensory neurons themselves.

Improvement of learning processes following chronic systemic administration of modafinil in mice.

This study was aimed at determining the effects of a chronic modafinil intraperitoneal administration on the rate of learning in a series of five serial spatial discrimination reversals (SSDR) in a T-maze. Results showed that a daily modafinil administration at 64 mg/kg but not at 32 mg/kg induced a faster learning rate as compared to controls. This learning improvement in experimental mice was due to the faster emergence of a win-stay rule over days of testing.

Evaluation of the possibility of detecting benzenic pollutants by direct spectrophotometry on PDMS solid absorbent.

Solid-phase extraction has become one of the most commonly used techniques for preconcentration of analytes from environmental samples. In the standard use of solid sorbent phases the extracted pollutants are subsequently eluted with a suitable organic solvent before chromatographic analysis. An alternative to this procedure is analysis of the adsorbed and concentrated pollutants by direct application of a spectroscopic method (fluorimetry or absorptiometry) to the phase.

Mutated mtDNA distribution in exponentially growing cell cultures and how the segregation rate is increased by the mitochondrial compartments.

A cell contains many copies of mitochondrial DNA. The distribution of a mitochondrial gene mutation in a cell culture is governed by the way in which the mtDNA molecules of a cell are replicated and partitioned between the two daughter cells during mitosis. Assuming that this partition process is random, we describe the evolution of the mitochondrial genetic state of a cell culture.

[Biological quality of seawater evaluated in situ with embryo-larval test of Crassostrea gigas and Mytilus galloprovincialis].

Embryos and larvae of bivalves are frequently used in marine ecotoxicology for the purpose of assessing seawater quality, because they are very sensitive to pollutants and provide rapid responses. Laboratory studies, however, cannot accurately simulate natural conditions. We conducted bivalve embryo-larval studies in situ at the marina of Arcachon (south-west French Atlantic coast), in order to assess 'biological quality' of the water.

Differential roles for nicotinic and muscarinic cholinergic receptors in sustained visuo-spatial attention? A study using a 5-arm maze protocol in mice.

A 5-arm maze was used to measure sustained visuo-spatial attention in C57Bl/6 mice and test the hypothesis of differential functional roles for central nicotinic and muscarinic receptors in mediating task performance. Mice were first trained to acquire the basic visual discrimination task in which, on each trial, one randomly chosen arm among the five open arms was baited and remained lit until an arm-choice was made. Mice were then submitted to attentional testing in which trials using light signals of 2, 1 or 0.