Structure of a novel class II phospholipase D: catalytic cleft is modified by a disulphide bridge

Phospholipases D (PLDs) are principally responsible for the local and systemic effects of Loxosceles envenomation including dermonecrosis and hemolysis. Despite their clinical relevance in loxoscelism, to date, only the SMase I from Loxosceles laeta, a class I member, has been structurally characterized. The crystal structure of a class II member from Loxosceles intermedia venom has been determined at 1.7 Å resolution. Structural comparison to the class I member showed that the presence of an additional disulphide bridge which links the catalytic loop to the flexible loop significantly changes the volume and shape of the catalytic cleft. An examination of the crystal structures of PLD homologues in the presence of low molecular weight compounds at their active sites suggests the existence of a ligand-dependent rotamer conformation of the highly conserved residue Trp230 (equivalent to Trp192 in the glycerophosphodiester phosphodiesterase from Thermus thermophofilus, PDB code: 1VD6) indicating its role in substrate binding in both enzymes. Sequence and structural analyses suggest that the reduced sphingomyelinase activity observed in some class IIb PLDs is probably due to point mutations which lead to a different substrate preference.     

Continental-scale patterns of Cecropia reproductive phenology: evidence from herbarium specimens

Plant phenology is concerned with the timing of recurring biological events. Though phenology has traditionally been studied using intensive surveys of a local flora, results from such surveys are difficult to generalize to broader spatial scales. In this study, contrastingly, we assembled a continental-scale dataset of herbarium specimens for the emblematic genus of Neotropical pioneer trees, Cecropia, and applied Fourier spectral and cospectral analyses to investigate the reproductive phenology of 35 species. We detected significant annual, sub-annual and continuous patterns, and discuss the variation in patterns within and among climatic regions. Although previous studies have suggested that pioneer species generally produce flowers continually throughout the year, we found that at least one third of Cecropia species are characterized by clear annual flowering behaviour. We further investigated the relationships between phenology and climate seasonality, showing strong associations between phenology and seasonal variations in precipitation and temperature. We also verified our results against field survey data gathered from the literature. Our findings indicate that herbarium material is a reliable resource for use in the investigation of large-scale patterns in plant phenology, offering a promising complement to local intensive field studies.     

An extracellular vesicle epitope profile is associated with acute myocardial infarction

The current standard biomarker for myocardial infarction (MI) is high‐sensitive troponin. Although powerful in clinical setting, search for new markers is warranted as early diagnosis of MI is associated with improved outcomes. Extracellular vesicles (EVs) attracted considerable interest as new blood biomarkers. A training cohort used for diagnostic modelling included 30 patients with STEMI, 38 with stable angina (SA) and 30 matched‐controls. Extracellular vesicle concentration was assessed by nanoparticle tracking analysis. Extracellular vesicle surface‐epitopes were measured by flow cytometry. Diagnostic models were developed using machine learning algorithms and validated on an independent cohort of 80 patients. Serum EV concentration from STEMI patients was increased as compared to controls and SA. EV levels of CD62P, CD42a, CD41b, CD31 and CD40 increased in STEMI, and to a lesser extent in SA patients. An aggregate marker including EV concentration and CD62P/CD42a levels achieved non‐inferiority to troponin, discriminating STEMI from controls (AUC = 0.969). A random forest model based on EV biomarkers discriminated the two groups with 100% accuracy. EV markers and RF model confirmed high diagnostic performance at validation. In conclusion, patients with acute MI or SA exhibit characteristic EV biomarker profiles. EV biomarkers hold great potential as early markers for the management of patients with MI.     

Phylogeny and taxonomy of Potamotrygonocotyle Mayes, Brooks & Thorson, 1981 (Monogenoidea: Monocotylidae) with a description of four new species

The marine-derived stingrays of Potamotrygonidae, endemic to South American river systems, host an interesting parasite fauna equally related to marine lineages. Among those lineages, the diversity and phylogenetic relationships within Potamotrygonocotyle - a monocotylid monogenoidean specific to potamotrygonids - are poorly known, since 9 of 10 species attributed to this genus have been described in the past 3 years. Here, we readdress the diversity of Potamotrygonocotyle after examining the gills of 436 potamotrygonid individuals representing 12 described and 14 potentially undescribed species of freshwater stingrays from 19 major river systems of South America (i.e. sub-basins). We recognized 12 valid species within the parasite genus, of which four are described in this study. Our taxonomic decisions were based on the phylogenetic analysis of 14 ingroup terminal taxa and 12 morphological characters, which resulted in the following hypothesis of sister-group relationships: ((P. dromedarius, P. tatianae sp. nov.), (P. rionegrense, P. auriculocotyle sp. nov., ((P. quadracotyle, P. umbella), (P. septemcotyle sp. nov., (P. chisholmae, P. uruguayense)), (P. tsalickisi, P. eurypotamoxenus, P. rarum, (P. tocantinsense sp. nov., P. aramasae))))). According to our hypothesis, the absence of autapomorphic features for some nominal species, and the re-evaluation of morphological variation among populations, led us to consider P. eurypotamoxenus and P. uruguayense as junior synonymys of P. tsalicksi and P. chisholmae, respectively. Finally, we address the importance of biogeographic and host representation, in order to fully understand the patterns of morphological variation and host specificity within this group. We found that hypotheses of species delimitation depend greatly on efforts to sample specimens throughout its distributional range and that host specificity within this genus varies dramatically among lineages.     

Circadian preferences in young adults: Psychometric properties and factor structure of the Portuguese version of the Preferences Scale (PS-6)

Morningness is a trait-like variable which has been extensively studied within chronobiology. Despite the number of existing measures to assess morningness, there is a need for brief instruments that are psychometrically sound to be used in applied settings. Accordingly, the modified version of the Preferences Scale (PS-6) comprises six items and was reported to have adequate reliability and satisfactory validity indicators. In this article, the psychometric properties of the Portuguese version of the PS-6 are reported. A total of 700 students attending medical school were recruited, and this sample was randomly divided into two groups. In the first group (n = 352), we assessed the internal consistency calculations and conducted a principal component analysis of the posited structure. In the second group (n = 348), we conducted a confirmatory factor analysis (CFA) using structural equation modeling. Overall, the results indicated that the PS-6 has adequate reliability (α = .75) and is constituted by two components: (I) preferred cognitive activities timings and (II) preferred sleeping–eating timings, respectively. In conclusion, the Portuguese version of the PS seems suitable for use in research and applied settings such as shift work schedules management. However, the applicability of the PS-6 in other samples and further validity indicators should be both investigated. The use of actigraphy and biological measures should also be collected to enhance the robustness of the PS-6.     

Potato field-inoculation in Ecuador with <Emphasis Type="Italic">Rhizophagus irregularis:</Emphasis> no impact on growth performance and associated arbuscular mycorrhizal fungal communities

The System of Rice Intensification (SRI), a management-based approach for improving rice production, has demonstrated various positive effects on rice plants’ growth, resilience and yield. These effects have been attributed in part to symbiotic interactions between rice plants and the microbes that live around, on and inside them; but research on this is still very limited. To examine such relationships, a multifunctional symbiotic fungus Trichoderma asperellum SL2 was evaluated to assess its effects, if any, on the germination and growth of young seedlings and then the subsequent performance of rice plants during their crop cycle. Greenhouse studies were conducted under gnotobiotic conditions to assess any effects associated with inoculating rice seeds with Trichoderma asperellum SL2 compared with uninoculated controls in terms of seedling establishment, an essential part of SRI methodology; and then assessing the capacity of this fungus to enhance the growth, physiological characteristics, nutrient uptake, and yield of rice plants growing under simulated SRI conditions. Results showed that the presence of Trichoderma asperellum SL2 in association with SRI cultural practices led to significant increases in rice seedling growth, germination rate, vigour index, and chlorophyll content, and elicited more favourable phenotypical responses from given genotype potential. The research observations further illustrated that for some parameters, there were no significant differences between inoculated and uninoculated SRI plants, both giving results superior to those for conventionally-grown plants even when inoculated. This indicated that SRI growing conditions are more favorable for Trichoderma to contribute towards the growth, physiological traits, nutrient uptake, and yield of plants, whereas conventional management methods diminish or inhibit these effects. Focused research remains to be done to establish how aerobic microbes such as Trichoderma can affect and accelerate the performance of rice plants being grown in SRI environments above and below ground.     

Neoleucinodes elegantalis (Lepidoptera: Crambidae): an organism invisible to the defences of tomato fruits

Insect–plant interactions involving species of the genus Solanum have been intensively studied, resulting in several articles on insect–plant interactions. However, the interactions between herbivores and the fruits of Solanum lycopersicum (tomato) are not well known. Neoleucinodes elegantalis is a borer that causes great yield losses in S. lycopersicum crops because of the direct damage that it causes to the fruits and the difficulty of controlling it. In the field, the outside of a tomato fruit infested with the larvae of N. elegantalis is visually similar to uninfested fruits. Even a minor injury by herbivores can elicit a defensive response. Due to the lack of studies on interactions between fruit borers and S. lycopersicum, our aim in this study was to determine the locations of S. lycopersicum fruit in which the N. elegantalis larvae prefer to feed. An evaluation of nutritional sources was done through histochemical and biochemical tests and the defensive response of the S. lycopersicum fruit to attack by N. elegantalis larvae was evaluated through the detection of protease inhibitors (PIs) and lipoxygenase (LOX) activity. Our results show that the columella region is preferred by the N. elegantalis larvae and that this region has a nutritional source. Furthermore, attack by N. elegantalis larvae in the columella does not induce a significant increase in lipoxygenase activity and PIs. Thus, our results provide a better understanding of the interaction between the larvae of N. elegantalis and S. lycopersicum fruits and a better understanding of the evolution of plant–herbivore interactions, with an emphasis on the choice of feeding location as a strategy to avoid plant defences.     

In Silico,In Vitro and In Vivo Toxicological Assessment of BPP-BrachyNH<Subscript>2</Subscript>, A Vasoactive Proline-Rich Oligopeptide from <Emphasis Type="Italic">Brachycephalus ephippium</Emphasis>

BPP-BrachyNH₂ is a proline-rich oligopeptide (PRO) firstly identified in skin secretion of the frog Brachycephalus ephippium, which possess in vitro inhibitory activity of angiotensin-I converting enzyme (ACE) and endothelium-dependent vasorelaxant activity. Considering its potential application in the treatment of cardiovascular diseases, the present work assessed the toxicological profile of the BPP-BrachyNH₂. The in silico toxicity prediction was performed from the best model obtained through the optimization of the FASTA query peptide. This prediction study revealed that BPP-BrachyNH₂ induced high predicted LD₅₀ values for both humans and rats, and then is well-tolerated in the recommended range. The MTT assay was applied for the in vitro cytotoxic evaluation in murine macrophages. In this assay, a decrease of cell viability was not observed. The in vivo acute toxicological study was performed after the intraperitoneal administration of BPP-BrachyNH₂ at doses of 5 and 50 mg/kg. After intraperitoneal administration, no death, alterations in behavioral parameters or weight gain curve was observed, as well as none in the serum biochemical parameters, and gross pathological and histopathological analyses. These observations demonstrates an acceptable safety profile for BPP-BrachyNH₂, leading towards further studies focused on investigation of pharmacological and therapeutical applications for this peptide.