Search

The hibernating golden hamster (Mesocricetus auratus) is becoming a useful rodent model to study the neurophysiological role of some neuromediators on vital behaviors such as sleep and thermoregulation. Recent works have shown that the histamine neuroreceptor subtypes ([H.sub.1-3]R) are able to modulate such behaviors. Here, specific subtype(s) and cerebral nuclei that were actively operating on feeding behaviors in pubertal and adult hamsters were identified. Of the subtypes assessed, [H.sub.3]R antagonist (thioperamide) provoked significant (p < .001) changes in behavior (very low total food and water intake) in adults, whereas it did not significantly modify these behaviors in pubertals. The [H.sub.3]R antagonist's role seemed to be related to elevated amounts of stress-induced damaged neurons displaying, mainly, shrunken crenated cell membranes and altered synaptic processes in limbic areas such as amygdala, cortex, and hippocampus. At the transcription level, an evident expression pattern of [H.sub.3]R messenger RNA appeared in pubertals, especially in neurons of the cortex and hippocampus, whereas the same trend was featured in amygdalar areas of hibernating adult hamsters, suggesting early [H.sub.3]R regulatory activities, at least in limbic sites of this rodent model. Keywords: histaminergic system, Syrian hamster, hibernation, [H.sub.3]R, neuroprotection

We examined, from a morphological and ultrastructural point of view, the gill epithelium of Triturus italicus, both in basal conditions and after acute exposure to low pH. Our analysis of gill morphology began with the aim of determining lethal pH levels; we found that the pH value at which 50% of mortality occurs (LC50) is 4.0. We then investigated the effects of the larvae's exposure to a critical value of pH (pH 4.5).No change was observed in the gill during the first 24 hr. After 48 hr, a cellular response was evident and the gills appeared covered with a dense mucous layer. Observations that were carried out by light microscopy (LM) and electron microscopy, both scanning (SEM) and transmission (TEM), showed considerable histological and ultrastructural changes.As regards the principal filament, the alterations resulted in the presence of an external keratinized layer. More changes affected the mitochondria‐rich cells (MRCs) in both a qualitative and quantitative way; this cell type shows a wide surface and seems to protrude more than the near pavement cells that, in normal conditions, partially cover the MRCs, thus reducing their external surface. The microvilli were extremely lengthened and often anatomized each other. Changes in the secondary filament affected the thickness of the epithelium, which appeared considerably smaller in the gills of the newts exposed to acid stress. The ciliated cells appeared to be more numerous than in the control specimens and the MRCs showed a widening of the apical surface. J. Exp. Zool. 303A:946–957, 2005. © 2005 Wiley‐Liss, Inc.

The appearance and the modification of the gill apparatus in Rana dalmatina tadpoles have been described in the different phases of larval development. The morphology and ultrastructure have been studied using light microscopy and both scanning and transmission electron microscopy. The organization of the gills during the initial phases of development (external gills or transient gills) brings to mind the characteristics of Urodela larvae in which the gills appear to consist of three tufts of filaments supported by the gill arches III, IV and V. The cellular composition of the transient gills appears to be extremely simple and the presence of specialized cells is not noted. Basal cells, pavement cells and ciliated cells form the thin mono- or bilayered epithelium. In the persistent gills (or internal gills) of the R. dalmatina tadpole (Orton’s larval type 4) the gill arches carry four rows of gill tufts branching out to the ventral region. Meanwhile, from the dorsal portion of the arch the gill filters present an axial portion from which there is much branching out, which confers a characteristic appearance on this part of the gills. The cellular composition of the gill tufts and of the filters is different: in the gill tufts basal cells, pavement cells, ciliated cells, cubic cells and mitochondria-rich cells (MRCs) have been recognized, while in the gill filters the last cellular type does not appear. The MRC has highly variable forms and dimensions and is characterized by the presence of numerous mitochondria in the cytoplasm. Often the MRCs manifest themselves grouped together, in groups of three or more. The pavement cells and the cubic cells demonstrate identical ultrastructural characteristics and have an external surface area characterized by the presence of short superficial microridges and numerous vacuoles in the apical cytoplasm.

Information is given on the distribution and ecology of amphibians in the Pollino National Park, based on a summary of the data contained in the Herpetology Laboratory database at the Ecology Department (University of Calabria) and updated with information obtained during recent sampling. A total of 412 stations was monitored revealing the presence of 11 amphibian species. Two of these (Bombina pachypus, Salamandrina terdigitata) are included in annex II and six (Rana italica, R. dalmatina, Hyla intermedia, Bufo viridis, Triturus italicus, T. carnifex) in annex IV of the 'Habitat' directive. Some species represent interesting Italian (T. carnifex, H. intermedia), Apennine (B. pachypus, R. italica, S. terdigitata) and southern Italian (T. italicus) endemisms, which further valorize the heritage of the Park's fauna. For each species the state of conservation was checked and evaluated in order to propose suitable strategies for protection.

We sampled 154 sites of Triturus italicus from central and southern Italy to infer conservation guidelines. In most sites, the species lives in small populations (tens of individuals) in natural (ponds, pools, streams) and artificial (ditches, wells, tanks, troughs) bodies of water. Its biological cycle regarding in-water movements and reproductive patterns is very variable. The species seems in decline, with the exception of Latium and Calabria, and 22 populations have become extinct. The main causes of the species disappearance are likely due to loss of habitats caused by trasformation or destruction of bodies of water by modern farming techniques, pollution, and introduction of allochtonous species (such as fishes and pond turtles). A status of “endangered” is suggested for the species, or “vulnerable” for the populations of Latium and Calabria. The species deserves a conservation plan which includes measures such as habitat protection, scientific monitoring aimed at abundance and genetic analysis, and the creation of corridors to allow genetic exchange. The protection and restoration of small artifical bodies of water could help reach these objectives.

The relationship of morphometrical and androgen receptor evaluations of the main testicular interstitium cellular element (Leydig cells) in the domestic pig provided interesting numerical and morphological features during the different aging stages. As early as 25 days (a period in which the pig is sexually immature) there was a low number of Leydig cells (1.46 × 10⁸) with respect to a 78% and 35% increase in the adult (2.48 × 108) and aged (1.78 × 10⁸) animal, respectively. Interestingly, when the volume density of Leydig cells was considered, the average volume of these cells seemed to be high (75%) in the aged pig with respect to the young immature animal whereas a lower increase (27%) was observed for the adult animal. Moreover, the evaluation of testosterone receptor binding sites in the testis at the various stages of development also displayed a differentiated pattern since elevated testosterone receptor binding levels of the high dissociation affinity type were obtained for the adult pig. Thus, from the combined morphological variations of Leydig cells and testosterone receptor binding activity, it appears that this androgenic receptor component exerts distinct autocrine effects on the different functional features of some testicular tissue constituents at the different aging stages of the domestic pig. J. Exp. Zool. 287:167–175, 2000. © 2000 Wiley-Liss, Inc.

To extend the study on bird spermiogenesis we have observed by electron microscopy the mature testis of the cuculiform Crotophaga am.During nucleus elongation the chromatin condenses in dense granules and the nucleoplasm is reducing. The Golgi apparatus starts the developing of the acrosomal vesicle. The elongating nucleus drives the acrosomal vesicle against the cell membrane. At the opposite side the flagellum arises from the distal centriole and comes out from the cell at a very early stage. While the cytoplasm is reducing, the mitochondria arrange themselves around the distal centriole and around the fore part of the axoneme.The elongating spermatid does not have a microtubular manchette or a microtubular bundle, as seen in other birds. It is entirely surrounded by a Sertoli cell, which shows many microtubules scattered in the cytoplasm. These microtubules are arranged parallel to the axis of elongating spermatids. Near the Sertoli cell membrane, surrounding the acrosome, is electron-dense material.The perforatorium, present in the sperm of Galliformes and Anseriformes, is absent. A subacrosomal space, found in Columbiformes sperm, is also absent.The morphogenetic factors influencing the head shape of this sperm seem to be peculiar and probably related to the microtubular apparatus of the Sertoli cell.

Linalool, a small monoterpene molecule, is used widely for its flavoring and fragrant properties in many cosmetic products. In this work, we investigated the antiproliferative effect of two different linalool solutions on RPMI 7932 human melanoma and NCTC 2544 normal keratinocites cell lines using the trypan blue method. Morphological changes in cells were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In addition, apoptosis was evaluated using caspase 3-antibody. Linalool showed a selective inhibitory effect on the growth of melanoma cells in a concentration-dependent manner, inducing several morphological changes, as revealed by SEM and TEM analysis. Moreover, the labelling for caspase-3 is abundant in the melanoma cells and almost absent in the normal keratinocites cells. The results suggest that linalool could be used as drug and/or as model drug for developing potential therapeutic agents for melanoma.