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The bullfrog, Lithobates catesbeianus, is one of the most important invasive anurans, affecting especially native anurans due to their similar habits. Here we used a hierarchical co-occurrence model fit in a Bayesian framework to investigate the effects of the bullfrog on two native frog species from southern Brazil, testing the hypothesis that bullfrog presence changes the activity of native species and their relationship with habitat. We found that both occupancy and detection probabilities of native species were similar with bullfrog presence or absence at a site. However, we observed changes in activity and microhabitat use preferences of both native species when the bullfrog was present, suggesting that the presence of the invasive species altered the behavior of the native species. Changes induced by invasive species can result in severe long-term consequences for native species since niche differentiation may not mediate the ability of species to persist together indefinitely.

In the original publication of the article, the last name of the first author was published incorrectly and the correct name is given in this correction.

The aim of this study was to measure the levels of purines in serum of rats experimentally infected with Leptospira interrogans serovar Icterohaemorrhagiae. For this purpose, 24 adult male Wistar rats were divided into two groups: A, not infected (subgroups A1 and A2), and B, infected (subgroups B1 and B2), which were intraperitoneally inoculated (day 0) with 2 × 108 leptospires/animal. Blood samples were collected on days 15 (A1 and B1) and 30 PI (A2 and B2) for analysis of purine levels in serum (adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), adenosine, inosine, hypoxanthine, xanthine, and uric acid). The levels of ATP, AMP, adenosine, and xanthine increased (P < 0.015), while a reduction (P < 0.015) in the concentration of ADP and inosine occurred at day 15 PI. On day 30 PI, ATP, ADP, adenosine, and uric acid significantly increased (P < 0.015), while xanthine level was reduced (P < 0.015). The correlation among the infection and purine levels lead us to suggest the purinergic system as a compensatory mechanism during the leptospirosis infection, mainly due to the actions of ATP, which usually is involved in a pro-inflammatory response, followed by a protective action of ADP and adenosine on the clotting events, along with a protective cellular damage caused by the infection.

The aim of this study was to assess the purine levels and E-ADA activity in the brain of mice (BALB/c) experimentally infected with Toxoplasma gondii. In experiment I (n=24) the mice were infected with RH strain of T. gondii, while in experiment II (n=36) they were infected with strain ME-49 of T. gondii. Our results showed that, for RH strain (acute phase), an increase in both periods in the levels of ATP, ADP, AMP, adenosine, hypoxanthine, xanthine (only on day 6 PI) and uric acid (only on day 6 PI). By the other hand, the RH strain led, on days 4 and 6 PI, to a reduction in the concentration of inosine. ME-49, a cystogenic strain, showed some differences in acute and chronic phase, since on day 6 PI the levels of ATP and ADP were increased, while on day 30 these same nucleotides were reduced. On day 60 PI, ME-49 induced a reduction in the levels of ATP, ADP, AMP, adenosine, inosine and xanthine, while uric acid was increased. A decrease of E-ADA activity was observed in brain on days 4 and 6 PI (RH), and 30 PI (ME-49); however on day 60 PI E-ADA activity was increased for infection by ME-49 strain. Therefore, it was possible to conclude that infection with T. gondii changes the purine levels and the activity of E-ADA in brain, which may be associated with neurological signs commonly observed in this disease.