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.     

Evidence of genetic monogamy in the lemur Indri (Indri indri)

Monogamy is a rare strategy among mammals but relatively common among primates. The study of the evolution of monogamy in mammals and primates is lacking empirical studies that assess the relationship between a pair‐living social organization and genetic monogamy. Sexual or genetic monogamy can only be assessed by performing molecular analyses and investigating rates of extra‐pair paternity (EPP). Studying the occurrence of EPP can provide valuable insights into reproductive strategies and their adaptive value. The indri is a pair‐living primate that lives in stable groups. Their social units are composed of the reproductive pair and up to four more individuals, but extra‐pair copulation (EPC) can occur. This raises the question of whether this event may or may not lead to EPP. Here, we investigated whether a pair‐living social organization corresponds to genetic monogamy in indris (Indri indri). We analyzed the paternity of 12 offspring from seven pairs using a set of six microsatellite loci on fecal samples (mean number of alleles 11.7 ± 1.8 (mean ± standard deviation). We found that in 92% of cases the genetic profile of the offspring matched the paired male of the group for all the loci considered. In the only case of paternity mismatch, the paternity assignment remained inconclusive. Our results show that I. indri genetic monogamy is the norm and supports the hypothesis that pair‐living social organization is associated with low EPP rate. Also, our results are in contrast with the hypothesis of infertility as a reason to engage in EPC for this species.     

Morphometrical and acoustical comparison between diploid and tetraploid green toads

In the present paper we compare, on the basis of morphometrical characters and acoustical properties of the advertisement calls, a sample of 158 male green toads (Bufo viridis complex) collected in 12 breeding populations of south Kazakstan and north Kyrgyzstan. The samples of three populations resulted in only diploid toads (2n = 22), those of eight populations in only tetraploid toads (2k=44) whereas in one locality diploid, tetraploid and many triploid toads were collected. Diploid toads show significantly larger body size and proportionally larger head and shorter limbs than both tetraploids and triploids, whereas no evident morphometrical differences were observed between triploids and tetraploids. Diploid advertisement calls have spectral and temporal properties that significantly differ from those of both triploid and tetraploid advertisement calls. In particular, diploids produce significantly longer calls with higher pulse-rates and lower frequencies than those of tetraploids. We address the question of the factors that could be responsible for these differences and we discuss four hypotheses: (1) the direct effect of polyploid mutation, (2) genetic drift, (3) reproductive character displacement and (4) environmental selection.     

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.     

Exploring Local Perceptions of and Attitudes toward Endangered François’ Langurs (Trachypithecus francoisi) in a Human-Modified Habitat

International Journal of Primatology - Understanding local community attitudes toward wildlife is critical for making context-sensitive conservation planning and management decisions that may...