Genetic analysis reveals candidate species in the Scinax catharinae clade (Amphibia: Anura) from Central Brazil

Scinax (Anura: Hylidae) is a species-rich genus of amphibians (113 spp.), divided into five species groups by morphological features. Cladistic analyses however revealed only two monophyletic clades in these groups: Scinax catharinae and Scinax ruber. Most species from the S. catharinae clade are found in Atlantic rainforest, except for Scinax canastrensis,S. centralis, S. luizotavioi, S. machadoi,S. pombali and S. skaios. In the present work, specimens of Scinax collected in Chapada dos Guimarães, central Brazil, were morphologically compatible with species from theS. catharinae group. On the other hand, genetic analysis based on mitochondrial (16S and 12S) and nuclear (rhodopsin) sequences revealed a nucleotide divergence of 6 to 20% between Scinax sp. and other congeners from the Brazilian savannah (Cerrado). Accordingly, Bayesian inference placed Scinax sp. in the S. catharinae clade with high support values. Hence, these findings strongly indicate the presence of a new species in the S. catharinae clade from the southwestern portion of the Brazilian savannah. To be properly validated as a novel species, detailed comparative morphological and bioacustic studies with other taxa from Brazil such asS. canastrensis, S. centralis, S. luizotavioi, S. machadoi, S. pombali and S. skaios are required.     

Design,Synthesis, Antimicrobial Evaluation and in Silico Studies of Eugenol-Sulfonamide Hybrids

Using molecular hybridization, specific sulfonamide derivatives of eugenol were synthesized with subtle modifications in the allylic chain of the eugenol subunit (and also in the nature of the substituent group in the sulfonamide aromatic ring) which allowed us to study the influence of structural changes on the antimicrobial potential of the hybrids. Antimicrobial test results showed that most of the synthesized hybrid compounds showed good activity with better results than the parent compounds. Molecular docking studies of the hybrids with the essential bacterial enzyme DHPS showed complexes with low binding energies, suggesting that DHPS could be a possible target for the antibacterial sulfonamide-eugenol hybrids. Furthermore, most of the final compounds presented similar docking poses to that of the crystallographic ligand sulfamethoxazole. The results obtained allow us to conclude that these are promising compounds for use as new leads in the search for new antibacterial sulfonamides.     

Identification of protein components in in vivo human acquired enamel pellicle using LC-ESI-MS/MS

The acquired enamel pellicle is a thin protein film forming upon exposure of tooth enamel surfaces to saliva. The structural analysis of this integument relies on efficient pellicle harvesting and protein identification procedures. Material from three individual subjects and two pooled samples yielded the identification by LC-ESI-MS/MS of 130 pellicle proteins of which 89 were found in three or more experiments. A high intersubject consistency in pellicle composition was observed.     

Exposure of small mammals to ticks and rickettsiae in Atlantic Forest patches in the metropolitan area of Recife, North-eastern Brazil

Between December 2007 and March 2009, small mammals were captured in 6 Atlantic Forest patches in Brazil. We assessed tick-host associations and whether they differ among forest strata, sites, seasons, and host age classes or between sexes. Moreover, we assessed the exposure of animals to Rickettsia spp. In total, 432 animals were captured and 808 ticks were found on 32·9% of them. Significant differences were found among host species, collection sites, and forest strata; microhabitat preference was a strong risk factor for tick infestation. The highest tick density rates were recorded in forest fragments settled in rural areas; 91·3% of the ticks were collected from animals trapped in these forest fragments. A high prevalence (68·8%) of antibodies to Rickettsia spp. was detected among animals. This study suggests that disturbed Atlantic Forest fragments provide an environment for ticks and small mammals, which are highly exposed to rickettsiae. It also indicates that forest patches settled in rural areas are usually associated with higher small mammal diversity as well as with higher tick density rates.     

Analyses of Cry1Ab Binding in Resistant and Susceptible Strains of the European Corn Borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae)

Cry1Ab toxin binding analysis was performed to determine whether resistance in laboratory-selected Ostrinia nubilalis strains is associated with target site alteration. Brush border membrane vesicles were prepared using dissected midguts from late instars of susceptible and resistant strains (Europe-R and RSTT) of O. nubilalis. Immunoblot analysis indicated that three different proteins bound to Cry1Ab toxin and were recognized by an anticadherin serum. In a comparison of resistant and susceptible strains, reduced Cry1Ab binding was apparent for all three bands corresponding to cadherin-like proteins in the Europe-R strain, while reduced binding was apparent in only one band for the RSTT strain. Real-time analysis of Cry1Ab binding to gut receptors using surface plasmon resonance suggested slight differences in affinity in both resistant strains. Additional binding analysis was conducted using ¹²⁵I-labeled Cry1Ab, Cry1Ac, and Cry1Aa. Slight differences were again observed between the resistant and susceptible strains for Cry1Ab binding. However, when binding of ¹²⁵I-labeled Cry1Aa was tested, a 10-fold reduction in the concentration of binding sites was observed in the Europe-R strain. Expression of the O. nubilalis cadherin gene was similar in both the resistant and susceptible strains and did not account for differences in binding. In combination, the results of the present work suggest that differences in susceptibility to Cry1A toxins in the Europe-R strain of O. nubilalis are associated with altered receptor binding, although the precise nature of this mechanism is still uncertain.     

Interrelationships among morphology, echotexture, and function of the bovine corpus luteum during the estrous cycle

It has been suggested that ultrasound image attributes are a potential indicator of physiological and functional status of the corpus luteum (CL) in several species, including cattle. The aims of this study were to evaluate CL morphological, functional and echotextural characteristics, and also to investigate the hypothesis that those attributes are correlated and change similarly throughout an estrous cycle. Ovaries of crossbred (Bos taurus taurus × Bos taurus indicus) heifers were evaluated using ultrasonography daily throughout an interestrus interval using a B-mode, real-time ultrasound machine equipped with a 5 MHz linear-array rectal transducer, during a natural estrous cycle (Experiment 1; n = 12) or during a shortened cycle, with luteolysis induction 10 d after estrus (Experiment 2; n = 6). Blood samples were collected for assay of plasma progesterone concentrations. Corpora lutea areas were measured and daily images of each CL were videotaped and digitized for computer-assisted analysis using custom-developed software. In Experiment 1, area of luteal tissue increased until a maximum value 10 d after estrus (P < 0.001), followed by a plateau phase, and then a decline beginning 14 d after estrus. Luteal tissue area was highly correlated to plasma progesterone concentrations (r = 0.86; P < 0.001). When luteolysis was induced in Experiment 2, loss of CL function (decrease in plasma progesterone concentrations to metestrous values) preceded tissue regression by 48 h (24 h compared with 72 h; P < 0.001). The mean pixel value of ultrasound images did not change in Experiment 1 (P > 0.70), but a day effect on this attribute was observed in Experiment 2 (P = 0.052). In contrast, mean pixel value was correlated to plasma progesterone concentrations in Experiment 1 (r = −0.63; P < 0.05), but not in Experiment 2 (r = −0.28; P > 0.10). In regard to CL heterogeneity, defined as the standard deviation of the mean pixel value of the luteal tissue, a time effect was observed following both natural (Experiment 1; P < 0.009) and luteolysis-induced (Experiment 2; P < 0.05) estrous cycles (P < 0.05). Moreover, this variable was correlated with plasma progesterone concentrations (r = −0.71 and −0.58 in Experiments 1 and 2, respectively; P < 0.01), indicating that CL images were more heterogeneous during metestrus and after luteolysis (functional regression). In summary, morphological and echotextural attributes were correlated with CL function and underwent similar changes during the estrous cycle. Luteal tissue heterogeneity, assessed by ultrasonography, is considered a potential indicator of CL functional status, because it is correlated to circulating progesterone concentrations.