Aluminium modulation of the photosynthetic carbon reduction cycle in Zea mays

Two-weeks-old maize (Zea mays L. cv. XL-72.3) plants were submitted to Al concentrations of 0-81 g m-3 for 20 d, after which the A1 concentration-dependent effects on CO2 uptake by the mesophyll tissue and subsequent CO2 assimilation in the photosynthetic carbon reduction cycle of bundle sheath cells were investigated. The net photosynthetic rate (PN) and stomatal conductance (gs) increased continuously up to 27 g m-3 Al, whereas the intercellular CO2 concentration showed minimum values with the 27 g m-3 Al treatment. Moreover, the starch and saccharide concentrations, and fructose-1,6-bisphosphatase did not change significantly with increasing Al concentrations. The photosynthetic electron transport rates along with photosystems 2 and 1 started falling from 9 g m-3 Al onwards, while thylakoid acyl lipid composition did not show a clear pattern. With the Al concentration at 81 g m-3, NADP-malate dehydrogenase activity decreased to minimum values, whereas the opposite occurred with those of pyruvate dikinase, NADP-malic enzyme, and phosphoenolpyruvate carboxylase. Thus in vivo Al concentrations modulate the photosynthetic reduction cycle, possibly by interacting with the carbon flow rate exported to the cytosol. Although the inhibition of NADP-malate dehydrogenase activity might limit pyruvate dikinase, NADP-malic enzyme, and phosphoenolpyruvate carboxylase activities, in vivo the balance between phosphoenolpyruvate production and its carboxylation remains unaffected.     

Development of a novel anti-biofilm peptide derived from profilin of Spodoptera frugiperda

Abstract

Candida yeast infections are the fourth leading cause of death worldwide. Peptides with antimicrobial activity are a promising alternative treatment for such infections. Here, the antifungal activity of a new antimicrobial peptide—PEP-IA18—was evaluated against Candida species. PEP-IA18 was designed from the primary sequence of profilin, a protein from Spodoptera frugiperda, and displayed potent activity against Candida albicans and Candida tropicalis, showing a minimum inhibitory concentration (MIC) of 2.5?µM. Furthermore, the mechanism of action of PEP-IA18 involved interaction with the cell membrane (ergosterol complexation). Treatment at MIC and/or 10?×?MIC significantly reduced biofilm formation and viability. PEP-IA18 showed low toxicity toward human fibroblasts and only revealed hemolytic activity at high concentrations. Thus, PEP-IA18 exhibited antifungal and anti-biofilm properties with potential applicability in the treatment of infections caused by Candida species.     

Esterase 2 as a fluorescent biosensor for the detection of organophosphorus compounds: docking and electronic insights from molecular dynamics

ABSTRACT

Organophosphorus compounds (OP) are mainly used in agriculture as pesticides. Unfortunately, each year many rural workers are intoxicated by these compounds and, many times, the diagnosis of the exact molecule causing the intoxication can be tardy, exposing the patients to a huge risk of death. One way of preventing this delay is the use of enzymatic biosensors like the enzyme Esterase 2 from Alicyclobacillus acidocaldarius (AaEST2), which is an efficient fluorescent biosensor for OP identification. However, although this enzyme has been well studied experimentally, the complete understanding of the energy transfer processes that occur between AaEST2 and OPs is still obscure, making it difficult the accurate identification of the OP. In order to better understand this process, we applied in this work molecular docking and molecular dynamics studies, together with the Förster fluorescence resonance energy transfer (FRET) theory, to achieve a better understanding of the fluorescence profiles that are described in the literature and correlate them to individual OPs. Our results suggest that the pesticides chlorpyrifos, diazinon, parathion and paraoxon are all capable of quenching the residue Trp85 from AaEST2, triggering fluorescence. This supports our hypothesis that AaEST2 can be used as a fluorescent biosensor for the detection of organophosphorus compounds.     

Homology Modeling of Wild-type,D516V,and H526L Mycobacterium Tuberculosis RNA Polymerase and Their Molecular Docking Study with Inhibitors

Abstract

Rifamicyns (Rifs) are antibiotic widely used for the treatment of tuberculosis (TB); nevertheless, their efficacy has been limited by a high percentage of mutations, principally in the rpoB gene. In this work, the first three-dimensional molecular model of the hypothetical structures for the wild-type and D516V and H526L mutants of Mycobacterium tuberculosis (mtRNAP) were elucidated by a homology modeling method. In addition, the orientations and binding affinities of some Rifs with those new structures were investigated. Our findings could be helpful for the design of new more potent rifamycin analogs.     

Preventing the return of smallpox: molecular modeling studies on thymidylate kinase from Variola virus

Smallpox was one of the most devastating diseases in the human history and still represents a serious menace today due to its potential use by bioterrorists. Considering this threat and the non-existence of effective chemotherapy, we propose the enzyme thymidylate kinase from Variola virus (VarTMPK) as a potential target to the drug design against smallpox. We first built a homology model for VarTMPK and performed molecular docking studies on it in order to investigate the interactions with inhibitors of Vaccinia virus TMPK (VacTMPK). Subsequently, molecular dynamics (MD) simulations of these compounds inside VarTMPK and human TMPK (HssTMPK) were carried out in order to select the most promising and selective compounds as leads for the design of potential VarTMPK inhibitors. Results of the docking and MD simulations corroborated to each other, suggesting selectivity towards VarTMPK and, also, a good correlation with the experimental data.     

Functional connectivity and genetic diversity of Eulaema atleticana (Apidae,Euglossina) in the Brazilian Atlantic Forest Corridor: assessment of gene flow

The mobility and dispersal of organisms affect population genetics and dynamics, and consequently affect persistence and the risk of extinction. Thus, it is important to understand how organisms move in the fragmented landscapes in order to manage populations and predict the effects of habitat changes on species persistence. This study evaluated the functional connectivity of an orchid bee (Eulaema atleticana Nemésio, 2009) with a high fidelity to forest habitats in the Brazilian Atlantic Forest Corridor by analyzing genetic diversity, spatial genetic structure, and gene flow estimated from microsatellite and mitochondrial markers. Genetic diversity was not correlated with area of the forest fragments, or with forest isolation. At the mosaic scale, Eulaema atleticana showed no significant or low genetic differentiation, indicating genetic homogeneity among forest fragments. A previous field study indicated that Eulaema atleticana was one of the most sensitive Euglossina bees to forest fragmentation but the present molecular analyses demonstrates that current gene flow is sufficient to maintain genetic variability at the mosaic scale.     

Habitat use of the ocelot (Leopardus pardalis) in Brazilian Amazon

Amazonia forest plays a major role in providing ecosystem services for human and sanctuaries for wildlife. However, ongoing deforestation and habitat fragmentation in the Brazilian Amazon has threatened both. The ocelot is an ecologically important mesopredator and a potential conservation ambassador species, yet there are no previous studies on its habitat preference and spatial patterns in this biome. From 2010 to 2017, twelve sites were surveyed, totaling 899 camera trap stations, the largest known dataset for this species. Using occupancy modeling incorporating spatial autocorrelation, we assessed habitat use for ocelot populations across the Brazilian Amazon. Our results revealed a positive sigmoidal correlation between remote‐sensing derived metrics of forest cover, disjunct core area density, elevation, distance to roads, distance to settlements and habitat use, and that habitat use by ocelots was negatively associated with slope and distance to river/lake. These findings shed light on the regional scale habitat use of ocelots and indicate important species–habitat relationships, thus providing valuable information for conservation management and land‐use planning.     

Fire ants: What do rural and urban areas show us about occurrence, diversity,and ancestral state reconstruction?

In South America, Solenopsis saevissima and S. invicta are the most common fire ants. Nests are founded in areas under anthropic interference like urban or rural areas, but S. invicta is found preferentially in those with the greatest anthropic interference. However, we do not know the rates at which they exist in anthropized areas next to high density of native vegetation. Areas with 60 to 90% of native Atlantic Forest were selected to verify the occurrence of both species in rural and urban areas. We investigated the molecular diversity and applied the reconstruction of the ancestral state analysis for each species. A total of 186 nests were analyzed and we found that the two species had the same proportion in the urban area. However, S. saevissima had a higher rate of prevalence in the rural area, in addition to having a greater number of haplotypes and ancestry associated with this type of habitat for the region. S. invicta had the same number of haplotypes in both rural and urban regions, and less haplotypic diversity. We conclude that S. saevissima is a species typically associated with rural areas and S. invicta, although present, is not dominant in urban areas. Keywords: Biodiversity, haplotype diversity, DNA barcoding, mtDNA