Unraveling the drought-responsive transcriptomes in nodules of two common bean genotypes during biological nitrogen fixation.

Common bean (Phaseolus vulgaris) can efficiently fix atmospheric nitrogen when associated with Rhizobia. However, drought stress impairs plant metabolic processes, especially the biological nitrogen fixation (BNF). Here, we assessed transcriptional responses in nodules of two common bean genotypes to drought stress under BNF reliance. The RNA-Seq analysis yielded a total of 81,489,262 and 72,497,478 high quality reads for Negro Argel and BAT 477 genotypes, respectively. The reads were mapped to the Phaseolus vulgaris reference genome and expression analysis identified 145 and 1451 differentially expressed genes (DEGs) for Negro Argel and BAT 477 genotypes, respectively. Although BAT 477 had more DEGs, both genotypes shared certain drought-responsive genes, including an up-regulated heat shock protein (HSP) and a down-regulated peroxidase, indicating shared pathways activated during drought in nodule tissue. Functional analysis using MapMan software highlighted the up-regulation of genes involved in abiotic stress responses, such as HSPs and specific transcription factors (TFs), in both genotypes. There was a significant down-regulation in metabolic pathways related to antioxidant protection, hormone signaling, metabolism, and transcriptional regulation. To validate these findings, we conducted RT-qPCR experiments for ten DEGs in nodules from both genotypes, for which the expression profile was confirmed, thus reinforcing their functional relevance in the nodule responses to drought stress during BNF. BAT 477 genotype exhibited more pronounced response to drought, characterized by a high number of DEGs. The strong down-regulation of DEGs leads to transcriptional disturbances in several pathways related to stress acclimation such as hormone and antioxidant metabolism. Additionally, we identified several genes that are known to play key roles in enhancing drought tolerance, such as HSPs and crucial TFs. Our results provide new insights into the transcriptional responses in root-nodules, an underexplored tissue of plants mainly under drought conditions. This research paves the way for potential improvements in plant-bacteria interactions, contributing to common bean adaptations in the face of challenging environmental conditions.

Development and characterization of novel microsatellite loci for the Blue-fronted Amazon (Amazona aestiva, Psittaciformes, Aves) and cross-species amplification for other two threatened Amazona species.

Parrots are among the most threatened avian groups of the world, with illegal pet trade being a major threat to some Amazon (Amazona genus) and macaw (Ara and Anodorhynchus genera) species. Population genetic studies and effective control of commercial breeders are important actions for the conservation of these parrot species; however, few microsatellite loci are available for most Amazona species to date. In this study, 25 polymorphic microsatellite loci were identified in silico and characterized for the Blue-fronted Amazon [Amazona aestiva (Aa)]. Loci were tested in 24 Blue-fronted Amazons from wild population from central Brazil with cross-species amplified in two individuals of Amazona vinacea (Av) and Amazona pretrei (Ap) from northeastern Minas Gerais and Rio Grande do Sul, in southeastern and south of Brazil, respectively. The number of alleles per locus for Aa ranged from 5 to 24 with an average of 13.1. Twenty-four and 25 loci were successfully amplified for Av and Ap, respectively. The observed and expected heterozygosities for Aa ranged from 0.27 to 1.00 and from 0.35 to 0.94, with averages of 0.75 and 0.85, respectively. Nine loci significantly deviated from Hardy-Weinberg equilibrium after Bonferroni correction (likely due to null alleles) and no significant linkage disequilibrium between loci pairs was detected. The combined paternity exclusion probability was very high, and the probability of identity was extremely low. This new set of microsatellite loci will be useful for analyzing population genetic structure and making conservation and management decisions, as well as for parentage analysis and the control of commercial breeding of Aa and potentially other Amazona species.

Racial and social disparities in the access to automated peritoneal dialysis - results of a national PD cohort.

The prevalence of patients on automated peritoneal dialysis (APD) is increasing worldwide and may be guided by clinical characteristics, financial issues and patient option. Whether socioeconomic factors at the patient level may influence the decision for the initial peritoneal dialysis (PD) modality is unknown. This is a prospective cohort study. The primary outcome of interest was the probability to start PD on APD. The inclusion criteria were adult patients incident in PD. Exclusion criteria were missing data for either race or initial PD modality. We used a mixed-model analysis clustering patients according to their PD center and region of the country. We included 3,901 patients of which 1,819 (46.6%) had APD as their first modality. We found a significant disparity for race and educational level with African American patients less likely to start on APD (Odds ratio 0.74 CI95% 0.58-0.94) compared to Whites whilst those with greater educational levels were more likely to start on APD (Odds ratio 3.70, CI95% 2.25-6.09) compared to illiterate patients. Limiting the use of APD in disadvantaged population may be unethical. Demographics and socioeconomic status should not be necessarily part of the decision-making process of PD modality choice.

Development of microsatellite markers for Hyacinth macaw (Anodorhynchus hyacinthinus) and their cross-amplification in other parrot species.

BACKGROUND: Hyacinth macaw Anodorhynchus hyacinthinus is the largest parrot of the world and is considered vulnerable to extinction due to its habitat loss and illegal trade associated to the international pet market demand. Genetic studies on this species are still incipient to generate a consistent characterization of the population dynamics and to develop appropriate conservation strategies. In this sense, microsatellite markers may support the detection of a population genetic structure for this bird species. However, at this time, none Hyacinth macaw species-specific primers for microsatellite loci have been so far established. This study aimed to develop and characterize polymorphic microsatellite markers for A. hyacinthinus and to check for their cross-amplification in other parrot species. FINDINGS: Sequences containing repeated dinucleotide motifs were prospected and optimized from a genomic library that was enriched for microsatellites using magnetic beads. The analyses of 43-57 samples from wild individuals of three distinct Brazilian subpopulations led to the characterization of five polymorphic microsatellite loci. Allele richness per locus ranged from two to 12. Three loci exhibited observed heterozygosity values higher than 50%, but the overall average value among all loci was close to 45%. In addition, successful primer cross-amplification was verified in seven other investigated species of Neotropical parrots. CONCLUSIONS: The newly developed markers have shown to be potentially useful for in situ and ex situ population studies to support future conservation actions of Hyacinth macaw and other parrots.

MIP-graphene-modified glassy carbon electrode for the determination of trimethoprim.

A novel sensitive electrochemical sensor was developed by electropolymerization of pyrrole (PY) and molecularly imprinted polymer (MIP) which was synthesized onto a glassy carbon electrode (GCE) in aqueous solution using cyclic voltammetry in the presence of Trimethoprim (TMP) as template molecules. Furthermore, a previous electrode modification was performed by deposition of a suspension of graphene on the electrode's surface. The performance of the imprinted and non-imprinted (NIP) films was evaluated by impedance spectroscopy (EIS) and cyclic voltammetry (CV) of a ferric solution. The molecularly imprinted film exhibited a high selectivity and sensitivity toward TMP. The sensor presented a linear range, between peak current intensity and logarithm of TMP concentration between 1.0 × 10(-6) and 1.0 × 10(-4)M. The results were accurate (with recoveries higher than 94%), precise (with standard deviations less than 5%) and the detection limit was 1.3 × 10(-7)M. The new sensor is selective, simple to construct and easy to operate. The MIP sensor was successfully applied to quantify TMP in urine samples.

Identification and validation of reference genes to study the gene expression in Gluconacetobacter diazotrophicus grown in different carbon sources using RT-qPCR.

Gluconacetobacter diazotrophicus strain PAL5 is a nitrogen-fixing endophytic bacterium originally isolated from sugarcane and later on was found to colonize other plants such as rice, elephant grass, sweet potato, coffee, and pineapple. Currently, G. diazotrophicus has been considered a plant growth-promoting bacterium due to its characteristics of biological nitrogen fixation, phytohormone secretion, solubilization of mineral nutrients and antagonism to phytopathogens. Reverse transcription followed by quantitative real-time polymerase chain reaction (RT-qPCR) is a method applied for the quantification of nucleic acids because of its specificity and high sensitivity. However, the decision about the reference genes suitable for data validation is still a major issue, especially for nitrogen-fixing bacteria. To evaluate and identify suitable reference genes for gene expression normalization in the diazotrophic G. diazotrophicus, mRNA levels of fourteen candidate genes (rpoA, rpoC, recA, rpoD, fabD, gmk, recF, rho, ldhD, gyrB, gyrBC, dnaG, lpxC and 23SrRNA) and three target genes (matE, omp16 and sucA) were quantified by RT-qPCR after growing the bacteria in different carbon sources. The geNorm and Normfinder programs were used to calculate the expression stabilities. The analyses identified three genes, rho, 23SrRNA and rpoD, whose expressions were stable throughout the growth of strain PAL5 in the chosen carbon sources. In conclusion our results strongly suggest that these three genes are suitable to be used as reference genes for real-time RT-qPCR data normalization in G. diazotrophicus.