The increased presence of repetitive motifs in the KDDR-plus recombinant protein,a kinesin-derived antigen from Leishmania infantum,improves the diagnostic performance of serological tests for human and canine visceral leishmaniasis

Visceral leishmaniasis (VL) is caused by protozoa belonging to the Leishmania donovani complex and is considered the most serious and fatal form among the different types of leishmaniasis, if not early diagnosed and treated. Among the measures of disease control stand out the management of infected dogs and the early diagnosis and appropriate treatment of human cases. Several antigens have been characterized for use in the VL diagnosis, among them are the recombinant kinesin-derived antigens from L. infantum, as rK39 and rKDDR. The main difference between these antigens is the size of the non-repetitive kinesin region and the number of repetitions of the 39 amino acid degenerate motif (6.5 and 8.5 repeats in rK39 and rKDDR, respectively). This repetitive region has a high antigenicity score. To evaluate the effect of increasing the number of repeats on diagnostic performance, we designed the rKDDR-plus antigen, containing 15.3 repeats of the 39 amino acid degenerate motif, besides the absence of the non-repetitive portion from L. infantum kinesin. Its performance was evaluated by enzyme-linked immunosorbent assay (ELISA) and rapid immunochromatographic test (ICT), and compared with the kinesin-derived antigens (rKDDR and rK39). In ELISA with human sera, all recombinant antigens had a sensitivity of 98%, whereas the specificity for rKDDR-plus, rKDDR and rK39 was 100%, 96% and 71%, respectively. When evaluated canine sera, the ELISA sensitivity was 97% for all antigens, and the specificity for rKDDR-plus, rKDDR and rK39 was 98%, 91% and 83%, respectively. Evaluation of the ICT/rKDDR-plus, using human sera, showed greater diagnostic sensitivity (90%) and specificity (100%), when compared to the IT LEISH (79% and 98%, respectively), which is based on the rK39 antigen. These results suggest that the increased presence of repetitive motifs in the rKDDR-plus protein improves the diagnostic performance of serological tests by increasing the specificity and accuracy of the diagnosis.     

DNA barcode reveals candidate species of Scinax and Ololygon (Anura: Hylidae) in Atlantic Forest

Molecular species delimitation methods are efficient tools to identify species, including the discovery of new taxa and cryptic organisms, thus being useful to biodiversity studies. In the present work, 16S mitochondrial sequences and cytochrome oxidase I (COI) were used to evaluate the richness of species in the genus Scinax and Ololygon from a biodiversity hotspot in Atlantic Forest. A total of 109 specimens formally belonging to eight species of Scinax and three species of Ololygon were collected in 13 localities along the state of Bahia (northeastern Brazil) and one site in Espírito Santo (southeastern Brazil). Of the Scinax species collected in this study, three were morphologically differentiated from other described species and identified as putative new species (Scinax sp.1, Scinax sp.2 and Scinax sp.3). The species delimitations were inferred using three different methods: ABGD, PTP and mPTP which allowed recognizing 11 Scinax species and five Ololygon species. Scinax sp. 1, Scinax sp. 2 and Scinax sp. 3, have been confirmed as new putative species and Ololygon argyreornata possibly contains cryptic species. We suggest additional studies, including morphological and bioacoustic data to validate these new putative species.     

Peptidylarginine deiminase 4 concentration,but not PADI4 polymorphisms,is associated with ICU mortality in septic shock patients

The objective of our study was to evaluate the association between peptidylarginine deiminase 4 (PAD4) concentration and its polymorphisms with mortality in patients with septic shock . We prospectively evaluated 175 patients aged over 18 years with septic shock upon intensive care unit (ICU) admission. However, 48 patients were excluded. Thus, 127 patients were enrolled in the study. At the time of the patients’ enrollment, demographic information was recorded. Blood samples were taken within the first 24 hours of the patient's admission to determine serum PAD4 concentrations and its polymorphism PADI4_89 [rs11203366], PADI4_94 [rs2240340] and PADI4_104 [rs1748033]. The mean age was 63.3 ± 15.2 years, 56.7% were male, PAD4 concentration was 4.62 (2.48‐6.20) ng/mL and the ICU mortality rate was 67.7%. The patients who died in the ICU had higher APACHE II and Sequential Organ Failure Assessment (SOFA) scores. In addition, PAD4 concentration was higher in patients who died during ICU stay. However, there were no differences regarding PADI4 polymorphisms and ICU mortality. In the logistic regression models, PAD4 concentrations were associated with ICU mortality when adjusted for APACHE II score and lactate (OR: 1.477; CI 95%: 1.186‐1.839; P < .001), and when adjusted for age, gender and APACHE II score (OR: 1.392; CI 95%: 1.145‐1.692; P < .001). In conclusion, PAD4 concentration, but not PADI4_89, PADI4_94 and PADI4_104 polymorphisms, is associated with ICU mortality in septic shock patients.     

In silico characterization of a cyanobacterial plant-type isoaspartyl aminopeptidase/asparaginase

Asparaginases are found in a range of organisms, although those found in cyanobacteria have been little studied, in spite of their great potential for biotechnological application. This study therefore sought to characterize the molecular structure of an L-asparaginase from the cyanobacterium Limnothrix sp. CACIAM 69d, which was isolated from a freshwater Amazonian environment. After homology modeling, model validation was performed using a Ramachandran plot, VERIFY3D, and the RMSD. We also performed molecular docking and dynamics simulations based on binding free-energy analysis. Structural alignment revealed homology with the isoaspartyl peptidase/asparaginase (EcAIII) from Escherichia coli. When compared to the template, our model showed full conservation of the catalytic site. In silico simulations confirmed the interaction of cyanobacterial isoaspartyl peptidase/asparaginase with its substrate, β-Asp-Leu dipeptide. We also observed that the residues Thr154, Thr187, Gly207, Asp218, and Gly237 were fundamental to protein–ligand complexation. Overall, our results suggest that L-asparaginase from Limnothrix sp. CACIAM 669d has similar properties to E. coli EcAIII asparaginase. Our study opens up new perspectives for the biotechnological exploitation of cyanobacterial asparaginases.     

Species‐poor and low‐lying sites are more ecologically unique in a hyperdiverse Amazon region: Evidence from multiple taxonomic groups

Aim

We analysed beta‐diversity patterns of various biological groups simultaneously, from the perspective of site ecological uniqueness. We also investigated whether ecological uniqueness variation could be explained by variations in environmental conditions and spatial variables.

Data

Central Amazonia.

Methods

We estimated the total beta diversity and ecological uniqueness for 14 biological groups, including plants and animals, sampled at the same sites on a mesoscale in central Amazonia, Brazil. The uniqueness values for all biological groups were combined in a single matrix (multi‐taxa matrix of site uniqueness), which was then used as a response variable matrix in a partial redundancy analysis. We also investigated differences in the uniqueness patterns between plant and animal groups.

Results

In general, plants showed higher total beta diversity than animals. For plants, uniqueness was explained mainly by environmental conditions, while for animals, uniqueness was also related to spatial variables. Although variation in uniqueness was mainly related to soil clay content, it is difficult to determine a single major environmental variable underlying the variation in uniqueness because the topographical gradient influences many of them, including soil clay content.

Main Conclusion

The uniqueness values were higher in low‐lying areas, indicating that near‐stream sites were more ecologically unique. Despite the lower number of species in the lowlands, their unique biota contributed strongly to the maintenance of the total beta diversity of the area. This finding should be considered in conservation plans that aim to represent and preserve the regional biota. Our approach proved to be useful to analyse and compare the ecological uniqueness of multiple taxa.

     

Pollination of <Emphasis Type="Italic">Machaerium opacum</Emphasis> (Fabaceae) by nocturnal and diurnal bees

With plants whose flowers open at night and stay open during the day, nocturnal pollinators may exploit floral resources before diurnal competitors. Moths, bats, and beetles are the most familiar nocturnal pollinators, whereas nocturnal bees as pollinators remain poorly understood. The common Cerrado tree Machaerium opacum (Fabaceae) has white and strongly scented melittophilous flowers, which first open at the night and remain open during the day and, thus, have the potential to be visited by both nocturnal and diurnal bees. We asked: (1) what is the plant’s breeding system? (2) when during the night do the flowers open? (3) what are the visual and olfactory floral cues? and (4) which nocturnal/diurnal bees visit and pollinate the flowers? We show that M. opacum is self-incompatible. Its flowers open synchronously at 03:30 h, produce nectar exclusively at night, and have an explosive mechanism of pollen presentation. The flowers have pure white petals, release strong scents during anthesis, and are pollinated by nocturnal and diurnal bees. We recorded four nocturnal and 17 diurnal species as flower visitors, with females of nocturnal species of Ptiloglossa (Colletidae) being the most abundant. After an initial pollen-releasing visit, only a minor amount of pollen remains in a flower. Several floral traits favor visits by nocturnal bees: (1) night-time flower opening, (2) nectar production at night, (3) almost complete pollen release during the first flower visit, and (4) pure white petals and strong odor production prior to sunrise, facilitating visual and olfactory detection of flowers when light is dim.     

Functional dimorphic enantiostyly in monomorphic enantiostylous species of the subtribe Cassiinae (Fabaceae‐Caesalpinioideae)

• Monomorphic enantiostylous species produce flowers with a displacement of the style to the left (L) or right (R) on the same individual, and may exhibit different dynamics for the production of these floral types, which may influence levels of selfing.
• We investigated the production dynamics of L and R floral types in seven species and a variety of monomorphic enantiostylous species of the genera Senna and Chamaecrista. Our hypothesis was that most species present similar proportions of floral morphs each day. Individuals were classified daily over a period of 7 days according to the functional status, i.e. the proportion of floral morphs as functionally L, R or reciprocal (REC, i.e. similar proportions of the two floral morphs), and also according to the number of consecutive days in which they exhibited the same functional status.
• All species presented low daily flower production. Most species had individuals classified as functionally R, L and REC, and tend to repeat the same functional status over a few days, although they may change functional status during the flowering period. All species exhibited individuals that were classified as functionally reciprocal when both the daily and total number of flowers produced over 7 days was considered. The occurrence of different functional status has not yet been reported in the literature for enantiostylous species.
• The distinct strategies observed in the dynamics of floral morph production seemed likely to minimise geitonogamy and to favour cross‐pollination between individuals (xenogamy).

     

Linking Biodiversity,the Environment and Ecosystem Functioning: Ecological Functions of Dung Beetles Along a Tropical Elevational Gradient

Biodiversity loss and anthropogenic environmental changes are known to impact ecosystem functions and services. However, there are still some uncertainties such as confounding environmental factors other than community attributes that affect ecosystem functioning. Our goal was to understand what factors influence the performance of Scarabaeinae dung beetle functions, testing the hypothesis that both community attributes and environmental variables influence the performance. Toward this aim, we collected dung beetles along an elevational gradient (800–1400 m a.s.l.) in the Espinhaço mountain range (Brazil) and quantified dung beetle functions, that is, dung removal, soil excavation and secondary seed dispersal. We recorded data on environmental factors related to climate, soil and vegetation and evaluated their effects on dung beetle functions. Dung beetle ecological functions declined with elevation and the decrease was more pronounced than richness, indicating that there are other factors involved in functions performance besides diversity of beetles. Indeed, we found that the ecological functions measured were dependent on both dung beetle community attributes and environmental factors. Climate, soil and vegetation influenced dung beetle function performance as much as richness, abundance and body size. Dung beetle functional diversity did not explain any of the functions measured. Our study demonstrates that ecological functions are directly influenced by both community attributes and environmental variables and confirms the link between biodiversity, environment and ecosystem functioning.