Franco Bernini

Increase in liver pigmentation during natural hibernation in some amphibians.

The amount/distribution of liver melanin in 3 amphibian species (Rana esculenta, Triturus a. apuanus, Triturus carnifex) was studied during 2 periods of the annual cycle (summer activity–winter hibernation) by light and electron microscopy, image analysis and microspectrofluorometry. The increase in liver pigmentation (melanin content) during winter appeared to be correlated with morphological and functional modifications in the hepatocytes, which at this period were characterised by a decrease in metabolic activity. These findings were interpreted according to the functional role (e.g. phagocytosis, cytotoxic substance inactivation) played by the pigment cell component in the general physiology of the heterothermic vertebrate liver and, in particular, in relation to a compensatory engagement of these cells against hepatocellular hypoactivity during the winter period.

Sperm allocation in relation to male traits, female size, and copulation behaviour in freshwater crayfish species

Sperm competition is a well-recognised agent in the evolution of sperm and ejaculate structure, as well as variation in female quality. Models of the evolution of ejaculate expenditure predict that male body condition, female fecundity and the risk and intensity of sperm competition may be the ultimate factors shaping optimal ejaculate size. We investigated sperm allocation in Austropotamobius italicus, a freshwater crayfish exhibiting a coercive mating system and external fertilisation, in relation to male and female traits and copulation behaviour under laboratory conditions. We found that mating males were sensitive to female size and produced larger ejaculates when mating with larger females, which were more fecund in terms of number of eggs produced. We found no evidence for female egg production being sperm-limited, as the number of eggs was not dependent on male sperm expenditure. Copulation duration and number of ejaculations reliably predicted the amount of sperm transferred, and both these behavioural measures positively covaried with female body size. These results indicate that male freshwater crayfish can modulate their sperm expenditure in accordance with cues that indicate female fecundity. In addition, a novel finding that emerged from this study is the decrease in sperm expenditure with male body size, which may either suggest that large, old male crayfish are better able than small males to economise sperm at a given mating to perform multiple matings during a reproductive season, or that they experience senescence of their reproductive performance.

Mechanisms of changes to the liver pigmentary component during the annual cycle (activity and hibernation) of Rana esculenta L.

The present study was performed to elucidate the mechanisms responsible for the changes of melanin content/distribution we had previously discovered in the liver parenchyma of Rana esculenta during natural hibernation. Melanomacrophagic component response was analysed using morphocytochemical methods. The results demonstrated that during the prehibernation period (October–November) the melanomacrophages reach the highest proliferative activity (BrdU, PCNA labelling) which is accompanied by an evident melanosynthesis (dopa‐oxidase activity). In contrast, after hibernation, the decrease of liver pigmentation was the consequence of a partial cell loss by apoptotic mechanisms (TUNEL labelling, pyknosis‐karyorhexis) accompanied by a decrease of melanosome content by autophagy and low melanosynthetic activity. On the basis of these findings, there is evidence that liver melanomacrophages represent a metabolically (melanin synthesis/degradation) and cytokinetically (proliferation/death) active cell population during the annual cycle of the frog. The results are also discussed in relation to the functional synergism between hepatocytes and pigment cells in the adaptation to environmental changes.

Histology of the metal-bone interface : interpretation of plastic embedded slides

The interference of processing and preparation of histological slides for the study of morphology and morphometry of bone-implant interfaces was investigated in an experimental model, in which a titanium plate was inserted through the cortical bone into the medullary cavity of rat tibiae. The thickness of the sections, burr and notching of the cut border, and staining properties of the embedding resin were found to significantly influence the appearance of the bone-implant interface and, when morphometry was applied, the extent of direct bone-metal contact. The model of the interface resulting from this study is that of some bony processes abutting on the metal surface, while most of the contact is between metal and connective tissue or vascular spaces.

Breeding Phenology of "Bufo viridis" Laurenti, 1768 in Sicily

Bufo viridis Laurenti, 1768 is a common species that inhabits a wide variety of habitats. The different climates characterising its broad range lead to a high degree of variability in its seasonal activity and reproductive cycle. This paper reports some observations carried out on the breeding phenology of this species over a two year period in Mediterranean temporary ponds in Sicily. The reproductive period of Sicil - ian green toads extends into the autumn months, making it longer than that of other Italian populations. This behaviour seems due to the impact of xeric environmental conditions on the seasonal activity of the studied populations. The present study con - firms that B. viridis is an opportunistic breeder with a wide margin of variability in annual reproductive cycle patterns, as would be expected of an ecologically variable species. The duration of the reproductive season varied between populations in the same year and between different years for the same population.

Distribution and conservation status of Bombina variegata in Italy (Amphibia, Bombinatoridae)

The present paper reports data on distribution, demographic parameters, ecological preferences and conservation status of Bombina variegata variegata and B. v. pachypas from the Italian peninsula. Owing to the wide distribution, we selected as a sample the following regions as sample regions: Lombardy, Veneto, Friuli-Venezia Giulia, Abruzzi, Latium, Campania, Basilicata, Apulia and Calabria, and the autonomous province of Trento3. For each region, we carried out bibliographic and museum researches, together with field surveys in order to collect updated faunistic data. B. v. variegata showed a general preference for hilly and mountain areas at medium/low elevation, under 1100 m. Our field surveys confirmed 44 sites out of 49 investigated; so the number of populations in northern Italy seems to be substantially stable. However, in several sites, particularly as regards prealpine Lombardy, a numerical decrease of individuals was observed; this fact suggests that this taxon could be threatened. B. v. pachypus predominantly inhabits areas at altitudes of less than 1400 m. Out of 55 sites where this taxon was found prior to 1996, the present study confirmed only 33. Nevertheless, the status of the B. v. pachypus populations from southern Italy seemed to be different, being vulnerable with respect to the populations of Abruzzi, Campania, Latium and Apulia, and not vulnerable as far as the Calabrian population is concerned. Finally, for both B. v. variegata and B. v. pachypus, we discuss threats and conservation perspectives.

Possible occurrence of amitotic cell division during haemopoiesis in the Urodeles

The liver haemopoietic activity of three species of Urodeles (Triturus carnifex, Triturus alpestris and Speleomantes ambrosii) was examined by morphocytochemical approaches (light and electron microscopy, anti-BrdU immunocytochemistry, flow cytometry). The proliferation of haemopoietic cells, detected by the anti-BrdU labelling index, was accompanied by absence of mitotic cell division and the appearance of cells showing features of amitosis (e.g. nuclear constrictions with bundles of electron-dense chromatin) sometime positive to the anti-BrdU immuno-gold reaction. The possible unbalanced segregation of chromatin during the direct division of the nucleus was detected by flow cytometric measurement in terms of heterogeneous relative DNA content in peripheral blood cells. The presence in the bloodstream samples of cells (erythrocytes) with replicating DNA, nuclear constrictions and binucleations is also consistent with a situation of direct nuclear division.

Distribution and status of Rana latastei in Italy (Amphibia, Ranidae)

Data regarding distribution, demographic parameters, ecological preferences and conservation status of Rana latastei in Italy are reported. By comparing bibliographic information and original field data, the authors wish to provide a first estimate concerning the possible risk of rarefaction of this species throughout the national territory. Observations were carried out in an area corresponding lo a large portion of the distribution range in Italy; in particular, the following regions were considered: Piedmont, Lombardy, Venetia and Friuli-Venezia Giulia. The populations of Rana latastei seem to have undergone a constant decline in recent decades; the species is threatened mainly from the limited extension and fragmentation of suitable habitats and should probably be considered in the category “vulnerable”.

Movement behaviour and shelter choice of the native crayfish Austropotamobius pallipes complex: survey on a population in a semi-natural pond in Northern Italy

This is a study of movements and artificial shelters use by a 3-year established population of Austropotamobius pallipes complex, in a lentic environment in the Parco Lombardo della Valle del Ticino (NW Italy). Home-checking and mark-recapture methods were used to investigate movements of 178 crayfish and shelter use by 389 crayfish in summer and in autumn. Most crayfish (97.2%) moved but the movement was highly variable. The greater part of the distances moved was less than 10 m day−1. Multi-hole bricks with one opening have been mostly selected, and the lower level was preferentially occupied; frequently a single crayfish per brick was found. The animals size affected the majority of the analysed variables: mean daily distance, area fidelity, level of shelter; on the other hand no case was significant for sex. The results highlight that this species is fairly mobile and could colonize waterbodies with similar features even rather rapidly. Mobility does not appear to affect the endangered status of this species.

Rana dalmatina and R. latastei: Habitat selection, fluctuation in egg clutch deposition and response to exceptional floods in northern Italy

Abstract A ten year census was carried out on Rana dalmatina and R. latastei egg masses deposited in 36 reproductive sites in a 10‐hectare area, subject to periodic flooding, on the banks of the Ticino River. The vegetation type surrounding reproductive sites was noted. There were no signs of decline in the populations of either frog species. The number of egg clutches fluctuated widely from year to year but no correlation between clutch number and either flooding or climate parameters were detected. R. dalmatina preferred partly open areas for reproductive sites, whereas R. latastei selected areas characterized by hygrophilous vegetation and a high tree canopy.