1,720,961 research outputs found
Parasitism by Amphibiocystidium sp. (Mesomycetozoea) in Rana italica Dubois, 1987 (Amphibia: Anura: Ranidae): preliminary data
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Caratterizzazione molecolare di una Heat shock cognate protein 70 (Hsc70) nel Rana esculenta c. dell'Italia centrale
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Modificazione degli steroidi sessuali e degli ormoni tiroidei in maschi di Rana esculenta complex catturati in diverse aree dell’Umbria
No full textShort-term cadmium exposure induces stress responses in frog (Pelophylax bergeri) skin organ culture
No full textThere have been a few studies on the negative effects of pollutants on amphibian skin, the first structural barrier that interacts with the environment and its potential contaminants. In this study an ex vivo skin organ culture from the amphibian Pelophylax bergeri was used to evaluate cell stress responses induced by short-term exposure to cadmium (Cd), a toxic heavy metal known to be an environmental hazard to both humans and wildlife. Histopathological studies were carried out on skin explants using light microscopy and changes in the expression of stress proteins, such as Metallothionein (MT) and Heat shock proteins (HSPs), were investigated by Real-time RT-PCR. Results revealed that amphibian skin reacts to Cd-induced stress by activating biological responses such as morphological alterations and dose- and time-dependent induction of Mt and Hsp70 mRNA expression, suggesting their potential role as biomarkers of exposure to Cd. This work provides a basis for a better understanding of the tissue-specific responses of amphibian skin as a target organ to Cd exposure and its in vitro use for testing potentially harmful substances present in the environment
The delayed effects of meteorological changes on the water frogs in Central Italy
No full textIn long-lived organisms, the impacts of
environmental changes may become evident after
time, possibly in future generations. In this study, we
attempt to reveal possible delayed effects of meteorological
changes on mixed populations of water frogs
living in small water bodies located in the Tiber River
basin, by using a time-lagged correlation analysis. The
analysis shows that the temperature–precipitation
pattern induces definite delayed effects, which suggest
two potential, possibly co-occurring, explanatory
effects: (I) a cumulative and symmetric effect on
mortality and (II) a point and asymmetric effect on
recruitment. Our data suggest that the water availability
in late summer–early autumn affects the survival of
tadpoles and migrating frogs, with no differential
effect on the parental species Pelophylax bergeri and
the hybrid Pelophylax kl. hispanicus, whereas autumn
precipitation has a greater impact on the fecundity
and/or reproductive success of the parental species.
The best time-lagged regression equations between
population data and the annual de Martonne aridity
index (IDMa) indicate that IDMa\20 mm C-1 is
critical for the persistence of the water frogs, and
predict that the studied populations will experience a
significant decline within the current scenario of
climate change
Characterization of the Skin Microbiota in Italian Stream Frogs (Rana italica) Infected and Uninfected by a Cutaneous Parasitic Disease
Full text linkIn human and wildlife populations, the natural microbiota plays an important role in health maintenance and the prevention of emerging infectious diseases. In amphibians, infectious diseases have been closely associated with population decline and extinction worldwide. Skin symbiont communities have been suggested as one of the factors driving the different susceptibilities of amphibians to diseases. The activity of the skin microbiota of amphibians against fungal pathogens, such as Batrachochytrium dendrobatidis, has been examined extensively, whereas its protective role towards the cutaneous infectious diseases caused by Amphibiocystidium parasites has not yet been elucidated in detail. In the present study, we investigated, for the first time, the cutaneous microbiota of the Italian stream frog (Rana italica) and characterized the microbial assemblages of frogs uninfected and infected by Amphibiocystidium using the Illumina next-generation sequencing of 16S rRNA gene fragments. A total of 629 different OTUs belonging to 16 different phyla were detected. Bacterial populations shared by all individuals represented only one fifth of all OTUs and were dominated by a small number of OTUs. Statistical analyses based on Bray-Curtis distances showed that uninfected and infected specimens had distinct cutaneous bacterial community structures. Phylotypes belonging to the genera Janthinobacterium, Pseudomonas, and Flavobacterium were more abundant, and sometimes almost exclusively present, in uninfected than in infected specimens. These bacterial populations, known to exhibit antifungal activity in amphibians, may also play a role in protection against cutaneous infectious diseases caused by Amphibiocystidium parasites
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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