Decreased plasma H2O2 levels are associated with the pathogenesis leading to COVID-19 worsening and mortality.

Oxidative Stress (OS) is involved in the pathogenesis of COVID-19 and in the mechanisms by which SARS-CoV-2 causes injuries to tissues, leading to cytopathic hypoxia and ultimately multiple organ failure. The measurement of blood glutathione (GSH), H2O2, and catalase activity may help clarify the pathophysiology pathways of this disease. We developed and standardized a sensitive and specific chemiluminescence technique for H2O2 and GSH measurement in plasma and red blood cells of COVID-19 patients admitted to the intensive care unit (ICU). Contrary to what was expected, the plasma concentration of H2O2 was substantially reduced (10-fold) in COVID-19 patients compared to the healthy control group. From the cohort of patients discharged from the hospital and those who were deceased, the former showed a 3.6-fold and the later 16-fold H2O2 reduction compared to the healthy control. There was a 4.4 reduction of H2O2 concentration in the deceased group compared to the discharged group. Interestingly, there was no variation in GSH levels between groups, and reduced catalase activity was found in discharged and deceased patients compared to control. These data represent strong evidence that H2O2 is converted into highly reactive oxygen species (ROS), leading to the worst prognosis and death outcome in COVID-19 patients admitted to ICU. Considering the difference in the levels of H2O2 between the control group and the deceased patients, it is proposed the quantification of plasma H2O2 as a marker of disease progression and the induction of the synthesis of antioxidant enzymes as a strategy to reduce the production of oxidative stress during severe COVID-19.HighlightsH2O2 plasma levels is dramatically reduced in patients who deceased compared to those discharged and to the control group.Plasmatic quantification of H2O2 can be possibly used as a predictor of disease progression.Catalase activity is reduced in COVID-19.GSH levels remain unchanged in COVID-19 compared to the control group.

Oligo-FISH barcode in beans: a new chromosome identification system.

KEY MESSAGE: An Oligo-FISH barcode system was developed for two model legumes, allowing the identification of all cowpea and common bean chromosomes in a single FISH experiment, and revealing new chromosome rearrangements. The FISH barcode system emerges as an effective tool to understand the chromosome evolution of economically important legumes and their related species. Current status on plant cytogenetic and cytogenomic research has allowed the selection and design of oligo-specific probes to individually identify each chromosome of the karyotype in a target species. Here, we developed the first chromosome identification system for legumes based on oligo-FISH barcode probes. We selected conserved genomic regions between Vigna unguiculata (Vu, cowpea) and Phaseolus vulgaris (Pv, common bean) (diverged ~ 9.7-15 Mya), using cowpea as a reference, to produce a unique barcode pattern for each species. We combined our oligo-FISH barcode pattern with a set of previously developed FISH probes based on BACs and ribosomal DNA sequences. In addition, we integrated our FISH maps with genome sequence data. Based on this integrated analysis, we confirmed two translocation events (involving chromosomes 1, 5, and 8; and chromosomes 2 and 3) between both species. The application of the oligo-based probes allowed us to demonstrate the participation of chromosome 5 in the translocation complex for the first time. Additionally, we detailed a pericentric inversion on chromosome 4 and identified a new paracentric inversion on chromosome 10. We also detected centromere repositioning associated with chromosomes 2, 3, 5, 7, and 9, confirming previous results for chromosomes 2 and 3. This first barcode system for legumes can be applied for karyotyping other Phaseolinae species, especially non-model, orphan crop species lacking genomic assemblies and cytogenetic maps, expanding our understanding of the chromosome evolution and genome organization of this economically important legume group.