Modulation of Synapsin I Gene Expression in Rat Cortical Neurons by Extracellular Matrix

1. Neuronal differentiation depends on crosstalk between genetic program and environmental cues. In this study we tried to dissect this complex interplay by culturing neurons from fetal rat brain cortices in a chemically defined, neuron-specific, medium and on different substrata, either artificial (poly-D-lysine) or natural.2. Among the extracellular matrix compounds used in this study, two (collagen I and fibronectin) allowed only a weak attachment of cortical neurons to the substratum, while the others (collagen IV, laminin, and basal lamina from Engelbreth-Holm-Swarm sarcoma) allowed both firm attachment and moderate to extensive neurite outgrowth from neuronal cell bodies.3. By using synapsin I gene expression as a parameter of neuronal differentiation, we found that neurite outgrowth and neuronal differentiation are not linearly linked. Synapsin I gene expression, in fact, was maximal in neurons cultured on laminin, while the fastest neuritic outgrowth was recorded in cultures on poly-D-lysine.4. The data presented in this paper are consistent with the hypothesis that the extracellular matrix plays an active role in modulating the differentiative program of neurons.     

Feeding Ecology and Regurgitation–Reingestion Behavior of the Critically Endangered Indri indri in the Maromizaha Protected Area,Eastern Madagascar

International Journal of Primatology - Deforestation around the world is a major threat to primates. Understanding primate species’ habitat and dietary requirements is critical in creating...     

Call Intensity and Female Preferences in the European Green Toad

In the present paper we study the pattern of variation in call intensity in a natural population of the European green toad (Bufo viridis), and we analyse females preferences for this property by means of playback experiments. Although call sound pressure level (SPL) shows little within‐bout variation, we found significant positive correlation between call SPL and fundamental frequency: on average, an increase of 6 dB SPL produces a 100‐Hz increase in fundamental frequency. When females were given a choice between two calls differing by 10 and 6 dB SPL, they significantly preferred the loudest call, whereas they did not discriminate between calls differing by 3 dB. To test whether a 3‐dB difference reflects a sensory or behavioural limit, we carried out three experiments where females were given a choice between two calls differing in both duration (4 s and 6 s, respectively) and SPL (3 dB). In all three experiments, the longer call attracted a larger number of females, but the 3‐dB difference did not show any significant effect. Finally, we investigated the relationships between call intensity and frequency on female preferences. Previous experiments showed size‐dependent preferences for calls with lower‐than‐average frequencies (1.3 kHz) over calls with higher‐than‐average frequencies (1.6 kHz). Here, we show that this weak preference is abruptly reversed when the highest‐pitched call is broadcast at an intensity 6 dB higher than the alternative.     

Acoustic divergence between bottlenose dolphin whistles from the Central–Eastern North Atlantic and Mediterranean Sea

To improve our understanding of the complex genetic and ecological structure of bottlenose dolphin (Tursiops truncatus) populations, we examined the acoustic features of communication signals from two geographically contiguous areas: the Central–Eastern North Atlantic and the Mediterranean Sea. Variations in the whistles were evaluated for four locations. Ten signal parameters were measured and used to statistically differentiate between the areas. Over 79 % of sightings were correctly classified by discriminant function analysis, confirming an acoustic differentiation between the two basins. The results of cluster analysis using the mean values of the parameters for each sighting showed that the three easternmost sightings from the Mediterranean and one sighting from the Canary archipelago formed a separate cluster from the rest of the Atlantic. The two sightings from the Alboran Sea in the west Mediterranean were grouped with the Atlantic recordings. There was more variability in whistles from the Atlantic Ocean consistent with data from genetic and photo-identification studies that document resident and non-resident animals in the area. The results suggest that the Alboran area may be inhabited by animals differentiated from the rest of the Mediterranean basin as a result of habitat features.     

The Advertisement Call of the European Treefrogs (Hyla arborea): A Multilevel Study of Variation

In this study, we analysed the patterns of variation of the European treefrog's advertisement call at four levels of organization: within individuals, within populations, among populations of the same species, and among different species of the same clade. At the within-individual level, call acoustic properties are distinguished into static and dynamic properties. At the within-population level, two sources of call variation were analysed: temperature and body size. Temperature affects both temporal and spectral properties of the call. Body size mostly affects spectral properties. At the between-population level, calls do not show significant differences with respect to temporal properties, but they do differ in two spectral (and stereotyped) properties: the fundamental frequency and the difference in amplitude between dominant and fundamental frequencies. Finally, at the between-species level, call differences are much more conspicuous: they involve both spectral and temporal and both static and dynamic properties. At all four levels, body size is associated with call variation, explaining 11% of the differences among populations of the same species and 73% of the differences among species of the same clade. On the basis of these results, we hypothesize that patterns of variation of call acoustic properties, their constraints, and their biological functions are intrinsically associated. We discuss the role that such an association might play in the evolution of acoustic signals.     

Interaction of peroxidized cardiolipin with rat-heart mitochondrial membranes: induction of permeability transition and cytochrome c release

Cardiolipin peroxidation plays a critical role in mitochondrial cytochrome c release and subsequent apoptotic process. Mitochondrial pore transition (MPT) is considered as an important step in this process. In this work, the effect of peroxidized cardiolipin on MPT induction and cytochrome c release in rat heart mitochondria was investigated. Treatment of mitochondria with micromolar concentrations of cardiolipin hydroperoxide (CLOOH) resulted in a dose-dependent matrix swelling, DeltaPsi collapse, release of preaccumulated Ca2+ and release of cytochrome c. All these events were inhibited by cyclosporin A and bongkrekic acid, indicating that peroxidized cardiolipin behaves as an inducer of MPT. Ca2+ accumulation by mitochondria was required for this effect. ANT (ADP/ATP translocator) appears to be involved in the CLOOH-dependent MPT induction, as suggested by the modulation by ligands and inhibitors of adenine nucleotide translocator (ANT). Together, these results indicate that peroxidized cardiolipin lowers the threshold of Ca2+ for MPT induction and cytochrome c release. This synergistic effect of Ca2+ and peroxidized cardiolipin on MPT induction and cytochrome c release in mitochondria, might be important in regulating the initial phase of apoptosis and also may have important implications in those physiopathological situations, characterized by both Ca2+ and peroxidized cardiolipin accumulation in mitochondria, such as aging, ischemia/reperfusion and other degenerative diseases.     

Cytokine/Chemokine HLDA8 Workshop panel report: analysis of receptors on lymphocytes from cord blood, normal and asthmatic subjects, and HIV positive patients

Chemokines and cytokines are involved in many processes, both physiological and pathological, particularly the recruitment, differentiation, activation, and proliferation of immune cells taking part in ontogenesis, inflammation, and cancer. It was assumed that chemokines and cytokines receptors are expressed in a regulated manner by human lymphocytes during ontogeny and later on, under the environmental stimulation of antigens they contribute to organogenesis, angiogenesis, and tissue remodeling, as well as modulating leukocyte effector functions. Using monoclonal antibodies classified by the Cytokine/Chemokine section of the 8th International Workshop on Human Leukocyte Differentiation Antigens, we analyzed human lymphocytes in blood samples drawn from the umbilical cord, normal adults, allergic and non-allergic asthma patients, HIV infected, and AIDS positive subjects. The main differences noted between adult and cord blood lymphocytes were related to CCR7 and CXCR4 receptors, which were more strongly expressed on cord blood lymphocytes, confirming the important role of these chemokines during development of the immune system. As with the HIV, CXCR4, and CCR5 co-receptors, we found no differences in CXCR4 expression between HIV and AIDS patients. However CCR5 was more strongly expressed in AIDS patients, which is likely to be associated with the evolution of disease. Further studies are needed to gain a better understanding of the functions of these molecules in the underlying pathogenesis of many diseases and to probe the use of the chemokine receptors as targets for therapeutic intervention.