Potamotrygon boesemani (Chondrichthyes: Myliobatiformes: Potamotrygonidae), a new species of Neotropical freshwater stingray from Surinam

Potamotrygon boesemani, new species, is described from the Corantijn river drainage in Surinam. The species has a diagnostic dorsal color pattern formed by deep orange to red ocellated spots of irregular form, encircled by relatively broad black rings. Potamotrygon boesemani is distinguished from other ocellated congeners (P. motoro, P. henlei and P. leopoldi) by the more intensely colored ocelli, which are usually yellow in the latter species. From P. motoro it is also distinguished by the darker dorsal background coloration, by the broader black contour of the dorsal ocelli, and by the irregular form of the ocelli as compared to the more rounded shape in the latter species. From P. henlei and P. leopoldi, it is distinguished by the lack of ocelli on tail. From the tentatively identified specimen of P. ocellata, which also has dark orange ocelli, the irregular contour of the ocelli in the new species is also distinctive. The teeth are relatively smaller and in greater number than in P. motoro and P. ocellata, with up to 45 rows in the upper jaw.

Antileishmanial and antitrypanosomal activity of bufadienolides isolated from the toad Rhinella jimi parotoid macrogland secretion

Amphibian skin secretions are considered a rich source of biologically active compounds and are known to be rich in peptides, bufadienolides and alkaloids. Bufadienolides are cardioactive steroids from animals and plants that have also been reported to possess antimicrobial activities. Leishmaniasis and American Trypanosomiasis are parasitic diseases found in tropical and subtropical regions. The efforts toward the discovery of new treatments for these diseases have been largely neglected, despite the fact that the only available treatments are highly toxic drugs. In this work, we have isolated, through bioguided assays, the major antileishmanial compounds of the toad Rhinella jimi parotoid macrogland secretion. Mass spectrometry and (1)H and (13)C NMR spectroscopic analyses were able to demonstrate that the active molecules are telocinobufagin and hellebrigenin. Both steroids demonstrated activity against Leishmania (L.) chagasi promastigotes, but only hellebrigenin was active against Trypanosoma cruzi trypomastigotes. These steroids were active against the intracellular amastigotes of Leishmania, with no activation of nitric oxide production by macrophages. Neither cytotoxicity against mouse macrophages nor hemolytic activities were observed. The ultrastructural studies with promastigotes revealed the induction of mitochondrial damage and plasma membrane disturbances by telocinobufagin, resulting in cellular death. This novel biological effect of R. jimi steroids could be used as a template for the design of new therapeutics against Leishmaniasis and American Trypanosomiasis. (C) 2008 Elsevier Ltd. All rights reserved.

Habitat fragmentation reduces genetic diversity and connectivity among toad populations in the Brazilian Atlantic Coastal Forest

Tropical rainforests are becoming increasingly fragmented and understanding the genetic consequences of fragmentation is crucial for conservation of their flora and fauna. We examined populations of the toad Rhinella ornata, a species endemic to Atlantic Coastal Forest in Brazil, and compared genetic diversity among small and medium forest fragments that were either isolated or connected to large forest areas by corridors. Genetic differentiation, as measured by F(ST), was not related to geographic distance among study sites and the size of the fragments did not significantly alter patterns of genetic connectivity. However, population genetic diversity was positively related to fragment size, thus haplotype diversity was lowest in the smallest fragments, likely due to decreases in population sizes. Spatial analyses of genetic discontinuities among groups of populations showed a higher proportion of barriers to gene flow among small and medium fragments than between populations in continuous forest. Our results underscore that even species with relatively high dispersal capacities may, over time, suffer the negative genetic effects of fragmentation, possibly leading to reduced fitness of population and cases of localized extinction. (C) 2008 Elsevier Ltd. All rights reserved.

Comparative analysis of two sampling techniques for pollen gathered by Nannotrigona testaceicornis Lepeletier (Apidae, Meliponini)

Pollen counts from samples taken from storage pots throughout one year (from October to September) were adjusted by Tasei's volumetric correction coefficient for the determination of pollen sources exploited by two colonies of Nannotrigona testaceicornis in Sao Paulo, Brazil. The results obtained by this sampling technique for seven months (December to June) were compared with those from corbicula load samples taken within the same period. This species visited a large variety of plant species, but few of them were frequently used. As a rule, pollen sources that appeared at frequencies greater than 1% were found with both sampling methods and significant positive correlations (Spearman correlation coefficient) were found between their values. The pollen load sample data showed that N. testaceicornis gathered pollen throughout the external activity period.

Patterns of viral load in chronic hepatitis B patients in Brazil and their association with ALT levels and HBeAg status

Serum hepatitis B virus (HBV) DNA [eve[ is a predictor of the development of cirrhosis and hepatocellullar carcinoma in chronic hepatitis B patients. Nevertheless, the distribution of viral load levels in chronic HBV patients in Brazil has yet to be described. This cross-sectional study included 564 participants selected in nine Brazilian cities located in four of the five regions of the country using the database of a medical diagnostics company. Admission criteria included hepatitis B surface antigen seropositivity, availability of HBV viral toad samples and age >= 18 years. Mates comprised 64.5% of the study population. Mean age was 43.7 years. Most individuals (62.1%) were seronegative for the hepatitis B e antigen (HBeAg). Median serum ALT level was 34 U/L. In 58.5% of the patients HBV-DNA levels ranged from 300 to 99,999 copies/mL; however, in 21.6% levels were undetectable. Median HBV-DNA level was 2,351 copies/mL. Over 60% of the patients who tested negative for HBeAg and in whom ALT level was less than 1.5 times the upper limit of the normal range had HBV-DNA levels > 2,000 IU/mL, which has been considered a cut-off point for indicating a liver biopsy and/or treatment. In conclusion, HBV-DNA level identified a significant proportion of Brazilian individuals with chronic hepatitis B at risk of disease progression. Furthermore, this tool. enables those individuals with high HBV-DNA levels who are susceptible to disease progression to be identified among patients with normal or stightly elevated ALT.

Blood gases and cardiovascular shunt in the South American lungfish (Lepidosiren paradoxa) during normoxia and hyperoxia

The South American lungfish (Lepidosiren paradoxa) has an arterial P(O2), (Pa(O2)) as high as 70-100 mm Hg, corresponding to Hb-O(2) saturations from 90% to 95%, which indicates a moderate cardiovascular right to left (R-L) shunt. In hyperoxia (50% O(2)), we studied animals in: (1) aerated water combined with aerial hyperoxia, which increased Pa(O2) from 78 +/- 2 to 114 +/- 3 mm Hg and (2) and aquatic hyperoxia (50% O(2)) combined room air, which gradually increased Pa(O2) from 75 +/- 4 mm Hg to as much as 146 +/- 10 mm Hg. Further, the hyperoxia (50%) depressed pulmonary ventilation from 58 +/- 13 to 5.5 +/- 3.0 mLBTPS kg h(-1), and Pa(CO2) increased from 20 +/- 2 to 31 +/- 4 mm Hg, while pHa became reduced from 7.56 +/- 0.03 to 7.31 +/- 0.09. At the same time, venous P(O2) (Pv(O2)) rose from 40.0 +/- 2.3 to 46.4 +/- 1.2 mm Hg and, concomitantly, Pvco, increased from 23.2 +/- 1.1 to 32.2 +/- 0.5 mm Hg. R-L shunts were estimated to about 19%, which is moderate when compared to most amphibians. (C) 2010 Elsevier B.V. All rights reserved.

Morphological, Morphometrical and Histochemical Study of the Lining and Glandular Epithelia of the Tongue of the Bullfrog Rana catesbeiana

The dorsal surface of the tongue of the bullfrog, Rana catesbeiana, has simple columnar epithelium with a few ciliated cells and goblet cells. The entire surface is covered with numerous filiform papillae and few fungiform. Filiform papillae have a simple columnar epithelium with secretory cells, while the fungiform have a sensory disc on their upper surface the lined by a stratified columnar epithelium with basal, peripheral, glandular and receptor cells. Over the dorsal lingual surface there are numerous winding tubular glands, which penetrate deeply into the muscle of the tongue, mingling with the fibers. The gland epithelium is cylindrical with secretory and supporting cells. The first are absolute on the basis of the gland and the latter are rare in the upper third. The ventral surface of the tongue is lined by a stratified epithelium, with the presence of goblet cells, with ciliated cells among them. Morphometrically, lingual glands varies in length, according to their location: shorter in the anterior region of the tongue (330 mu m) than in the posterior region (450 mu m). Secretory cells of the anterior lingual glands are smaller (1457.7 mm(3)) than the posterior ones (2645.9 mu m(3)). The same can be said of the cell nuclei, 130.0 mu m(3) for the anterior glands and 202.3 mu m(3) for the posterior ones. Secretory cells of the lingual glands contain substances rich in protein and neutral mucopolysaccharides, which characterize the seromucous type. Goblet cells of the dorsal and ventral surface epithelia secrete neutral mucopolysaccharides and proteins, and can be characterized as type G1 cells, and the supporting cells of the superficial glands of the fungiform papillae secrete a mucus rich in neutral mucopolysaccharides, sulfomucins and sialomucins.

Role of central nitric oxide in behavioral thermoregulation of toads during hypoxia

Nitric oxide (NO) is thought to play a key role in the development of hypoxia-induced anapyrexia in mammals, acting on the preoptic region of the anterior hypothalamus to activate autonomic heat loss responses. Regarding behavioral thermoregulation, no data exists for NO modulation/mediation of thermoregulatory behavior changes during hypoxia. Therefore, we tested the hypothesis that NO is involved in the preferred body temperature (Tb) reduction in the hypoxic toad Chaunus schneideri (formerly Bufo paracnemis), a primarily behavioral thermoregulator. Toads equipped with a temperature probe were placed in a thermal gradient chamber, and preferred Tb was monitored continuously. We analyzed the effect of intracerebroventricular injections of the nonselective NO synthase inhibitor L-NMMA (200, 400 and 800 microg per animal) or mock cerebrospinal fluid (mCSF, vehicle) on the preferred Tb of toads. No significant difference in preferred Tb was observed after L-NMMA treatments. Another group of toads treated with 2 mg kg(-1) (400 microg per animal) of L-NMMA or mCSF was submitted to hypoxia (3% inspired 02) for 8 h. The vehicle group showed a reduction of preferred Tb, a response that was inhibited by L-NMMA. A 3rd group of hypoxic animals was injected with Ringer or L-NMMA (2 mg kg(-1)) into the lymph sac and both treatments induced no change in the anapyretic response to hypoxia. These results indicate that NO acting on the central nervous system has an excitatory role for the development of hypoxia-induced anapyrexia in toads. (C) 2008 Elsevier Inc. All rights reserved.

Comparative study in stingless bees (Meliponini) demonstrates that nest entrance size predicts traffic and defensivity

Stingless bees (Meliponini) construct their own species-specific nest entrance. The size of this entrance is under conflicting selective pressures. Smaller entrances are easier to defend; however, a larger entrance accommodates heavier forager traffic. Using a comparative approach with 26 species of stingless bees, we show that species with greater foraging traffic have significantly larger entrances. Such a strong correlation between relative entrance area and traffic across the different species strongly suggests a trade-off between traffic and security. Additionally, we report on a significant trend for higher forager traffic to be associated with more guards and for those guards to be more aggressive. Finally, we discuss the nest entrance of Partamona, known in Brazil as boca de sapo, or toad mouth, which has a wide outer entrance but a narrow inner entrance. This extraordinary design allows these bees to finesse the defensivity/traffic trade-off.

Chromosomal studies in four species of genus Chaunus (Bufonidae, Anura): localization of telomeric and ribosomal sequences after fluorescence in situ hybridization (FISH)

Fluorescence in situ hybridization (FISH) using telomeric and ribosomal sequences was performed in four species of toad genus Chaunus: C. ictericus, C. jimi, C. rubescens and C. schneideri. Analyses based on conventional, C-banding and Ag-NOR staining were also carried out. The four species present a 2n = 22 karyotype, composed by metacentric and submetacentric chromosomes, which were indistinguishable either after conventional staining or banding techniques. Constitutive heterochromatin was predominantly located at pericentromeric regions, and telomeric sequences (TTAGGG)(n) were restricted to the end of all chromosomes. Silver staining revealed Ag-NORs located at the short arm of pair 7, and heteromorphism in size of NOR signals was also observed. By contrast, FISH with ribosomal probes clearly demonstrated absence of any heteromorphism in size of rDNA sequences, suggesting that the difference observed after Ag-staining should be attributed to differences in chromosomal condensation and/or gene activity rather than to the number of ribosomal cistrons.

A new species of Dendrophryniscus (Amphibia, Anura, Bufonidae) from the Atlantic Rainforest of southern Bahia, Brazil

A new species of the tree toad genus Dendrophryniscus is described from a rainforest habitat at Parque Nacional de Serra das Lontras, municipality of Arataca, southern Bahia, Brazil. Dendrophryniscus oreites sp. nov. is related to the Atlantic forest brevipollicatus group by hand morphology, skin texture, ventral coloration and bromelicolous habits. The new species differs from related species by having a larger size, warty skin, inner finger reduced with presence of a dark nuptial pad in males, and a yellowish coloration with discrete dorsal pattern. This discovery highlights the importance of southern Bahia in terms of conservation, and for our understanding of the evolution of the frog diversity within the Atlantic Rainforest.