Sitosterol-mediated Antioxidant Regulation to Enhance Heat Tolerance in Creeping Bentgrass

Heat stress symptoms in cool-season plants are characterized by loss of chlorophyll (Chl) and membrane stability, as well as oxidative damage. The objectives of this study were to determine whether foliar application of β-sitosterol, a naturally occurring plant metabolite, may promote heat tolerance by suppressing heat-induced leaf senescence as indicated by the maintenance of healthy turf quality (TQ), and Chl and membrane stability; and to determine its roles in regulating antioxidant metabolism in creeping bentgrass (Agrostis stolonifera). ‘Penncross’ plants were exposed to heat stress (35/30 °C day/night) optimal temperature conditions (nonstressed control, 22/17 °C day/night) for a duration of 28 days in environment-controlled growth chambers. Plants were foliar-treated with β-sitosterol (400 µM) or water only (untreated control) before heat stress, and at 7-day intervals through 28 days of heat stress. Plants treated with β-sitosterol had significantly greater TQ and Chl content, and significantly less electrolyte leakage (EL) than untreated controls at 21 and 28 days of heat stress. Application of β-sitosterol reduced malondialdehyde (MDA) content significantly at 21 and 28 days of heat stress, and promoted the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) from 14 through 28 days of heat stress. β-Sitosterol effectively improved heat tolerance through suppression of leaf senescence in creeping bentgrass exposed to heat stress in association with the alleviation of membrane lipid peroxidation and activation of the enzymatic antioxidant system.

The Role of Outer Membrane Protein(s) Harboring SLH/OprB-Domains in Extracellular Vesicles’ Production in Synechocystis sp. PCC 6803

Cyanobacteria are a group of photosynthetic prokaryotes that contribute to primary production on a global scale. These microorganisms release vesicles to the extracellular environment, spherical nanosized structures, derived essentially from the outer membrane. Even though earlier works in model Gram-negative bacteria have hypothesized that outer membrane stability is crucial in vesicle formation, the mechanisms determining vesicle biogenesis in cyanobacteria remain unknown. Here, we report on the identification of six candidate genes encoding outer membrane proteins harboring SLH/OprB-domains in the genome of the model cyanobacterium Synechocystis sp. PCC 6803. Using a genetics-based approach, one gene was found to encode an essential protein (Slr1841), while the remaining five are not essential for growth under standard conditions. Vesicle production was monitored, and it was found that a mutant in the gene encoding the second most abundant SLH/OprB protein in Synechocystis sp. PCC 6803 outer membrane (Slr1908) produces more vesicles than any of the other tested strains. Moreover, the Slr1908-protein was also found to be important for iron uptake. Altogether, our results suggest that proteins containing the SLH/OprB-domains may have dual biological role, related to micronutrient uptake and to outer membrane stability, which, together or alone, seem to be involved in cyanobacterial vesicle biogenesis.

ZDHHC19 localizes to the cell membrane of spermatids and is involved in spermatogenesis

Sperm is the ultimate executor of male reproductive function. Normal morphology, quantity, and motility of sperm ensure the normal reproductive process. Palmitoylation is a posttranslational modification mediated by palmitoyltransferases whereby palmitoyl is added to proteins. Seven palmitoyltransferases have been identified in Saccharomyces cerevisiae and 23 in humans (including ZDHHC1–9 and ZDHHC11–24), with corresponding homologs in mice. We identified two testis-specific palmitoyltransferases ZDHHC11 and ZDHHC19 in mice. The Zdhhc11 and Zdhhc19-knockout mouse models were constructed, and it was found that the Zdhhc11 knockout males were fertile, while Zdhhc19 knockout males were sterile. ZDHHC19 is located in the cell membrane of step 4–9 spermatids in the mouse testis, and phenotypic analysis showed that the testicular weight ratio in the Zdhhc19−/− mice decreased along with the number and motility of the sperm decreased, while sperm abnormalities increased, mainly due to the “folded” abnormal sperm caused by sperm membrane fusion, suggesting the involvement of ZDHHC19 in maintaining membrane stability in the male reproductive system. In addition, Zdhhc19−/− mice showed abnormal sperm morphologies and apoptosis during spermatogenesis, suggesting that spermatogenesis in the Zdhhc19−/− mice was abnormal. These results indicate that ZDHHC19 promotes membrane stability in male germ cells. Summary sentence: ZDHHC19 is located in the cell membrane of Step4–9 spermatids in mouse testis; Zdhhc19 knockout mice showed male infertility, abnormal spermatogenesis, sperm morphology and motility.

Effects of levamisole on haematological and oxidative stress parameters in packed donkeys

Stress can be caused by psychological, physiological, environmental and physical factors. Strenuous exercise like packing in donkeys modifies haematologic parameters. The aim of the study was to investigate the ameliorative effects of levamisole on stress, in packed donkeys. 15 adult male donkeys aged between 4 – 5 years were selected for this study, divided into groups (A, B, C) of five donkeys each: Groups A and B donkeys were the apparently healthy group; while Group C donkeys were naturally infected with Strongyle spp. All the donkeys participated in load carrying (packing) of 40 kg for 10 km. Groups B and C were treated with levamisole at 7.5 mg/kg, while Group A received no treatment prior to packing. Blood was collected from all the groups for haemogram and oxidative stress biomarker analyses. No significant effect (P > 0.05) was observed between groups: A, B and C for: respiratory rate, pulse rate and rectal temperature; haemogram, and activities of malondialdehyde concentration, superoxide dismutase and catalase. Erythrocyte membranes were osmotically stable at 0.5% NaCl in the treated group in comparison to the controls. Packing of donkeys for 10 km did not induce significant changes in vital parameters, haemogram and biomarkers of oxidative stress, but levamisole improved erythrocyte membrane stability. It was concluded that packing for 10 km did not induce any significant changes in blood cellular components and biomarker of oxidative stress, but levamisole improved erythrocyte membrane stability.

Chromosome length and gene density contribute to micronuclear membrane stability

Micronuclei are derived from missegregated chromosomes and frequently lose membrane integrity, leading to DNA damage, innate immune activation, and metastatic signaling. Here, we demonstrate that two characteristics of the trapped chromosome, length and gene density, are key contributors to micronuclei membrane stability and determine the timing of micronucleus rupture. We demonstrate that these results are not due to chromosome-specific differences in spindle position or initial protein recruitment during post-mitotic nuclear envelope assembly. Micronucleus size strongly correlates with lamin B1 levels and nuclear pore density in intact micronuclei, but, unexpectedly, lamin B1 levels do not completely predict nuclear lamina organization or membrane stability. Instead, small gene-dense micronuclei have decreased nuclear lamina gaps compared to large micronuclei, despite very low levels of lamin B1. Our data strongly suggest that nuclear envelope composition defects previously correlated with membrane rupture only partly explain membrane stability in micronuclei. We propose that an unknown factor linked to gene density has a separate function that inhibits the appearance of nuclear lamina gaps and delays membrane rupture until late in the cell cycle.

Exogenous Myo-inositol Alleviates Salt Stress by Enhancing Antioxidants and Membrane Stability via the Upregulation of Stress Responsive Genes in Chenopodium quinoa L.

Myo-inositol has gained a central position in plants due to its vital role in physiology and biochemistry. This experimental work assessed the effects of salinity stress and foliar application of myo-inositol (MYO) on growth, chlorophyll content, photosynthesis, antioxidant system, osmolyte accumulation, and gene expression in quinoa (Chenopodium quinoa L. var. Giza1). Our results show that salinity stress significantly decreased growth parameters such as plant height, fresh and dry weights of shoot and root, leaf area, number of leaves, chlorophyll content, net photosynthesis, stomatal conductance, transpiration, and Fv/Fm, with a more pronounced effect at higher NaCl concentrations. However, the exogenous application of MYO increased the growth and photosynthesis traits and alleviated the stress to a considerable extent. Salinity also significantly reduced the water potential and water use efficiency in plants under saline regime; however, exogenous application of myo-inositol coped with this issue. MYO significantly reduced the accumulation of hydrogen peroxide, superoxide, reduced lipid peroxidation, and electrolyte leakage concomitant with an increase in the membrane stability index. Exogenous application of MYO up-regulated the antioxidant enzymes' activities and the contents of ascorbate and glutathione, contributing to membrane stability and reduced oxidative damage. The damaging effects of salinity stress on quinoa were further mitigated by increased accumulation of osmolytes such as proline, glycine betaine, free amino acids, and soluble sugars in MYO-treated seedlings. The expression pattern of OSM34, NHX1, SOS1A, SOS1B, BADH, TIP2, NSY, and SDR genes increased significantly due to the application of MYO under both stressed and non-stressed conditions. Our results support the conclusion that exogenous MYO alleviates salt stress by involving antioxidants, enhancing plant growth attributes and membrane stability, and reducing oxidative damage to plants.

Whole Blood Adhesion to VCAM-1 and P-Selectin and RBC Mechanical Fragility Can be Compromised in Long COVID-19 Patients with Sickle Cell Disease

Introduction: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can cause severe vascular complications associated with endothelial dysfunction and systemic inflammation. COVID19-specific IgG are detectable within a week of infection. Long COVID-19 has been described in patients continuing to exhibit symptoms after the virus is no longer detectable in the respiratory secretions, including fatigue, dyspnea, headache, and brain fog. The recent FAIR Health study reviewed a total of 1,959,982 COVID-19 patients for the prevalence of long COVID symptoms and reported that 23.2% had at least one post-COVID symptom [1]. The underlying biologic mechanisms of long COVID remain unclear, thus treatments are limited to symptomatic relief and supportive care. Many long COVID symptoms are consistent with systemic inflammation and impaired oxygen delivery observed in individuals with sickle cell disease (SCD), in turn associated with elevated blood cell adhesion and decreased red blood cell (RBC) stability. The aim of this study was to determine if deleterious changes in in blood cell properties related to adhesion and membrane stability under stress can be associated with the symptoms of long COVID-19. In this work we evaluated 7 SCD patients that were diagnosed with SARS-Cov-2 and tracked their recovery using semiquantitative IgG and blood cell function assays. Methods: Blood samples were collected by the Foundation for Sickle Cell Disease (SCD) Research from SCD (homozygous SS, n=6) patients coming for regular or urgent clinic visit with SARS-CoV-2 serological and blood cell functions tests performed per the standard of care. Semiquantitative IgG assay was performed using DXi-80 (Beckman Coulter). Flow adhesion of whole blood to VCAM-1 (FA-WB-VCAM)and P-Selectin (FA-WB-Psel) substrates were determined by counting the cells that remain adherent in a microfluidics channel after perfusion with whole blood 1:1 diluted with HBSS buffer and washed by reversed flow at 1 dyne/cm 2. Red blood cell mechanical fragility (RBC MF) was measured as hemolysis induced by an oscillating cylindrical magnet with periodic non-invasive probing of cell-free hemoglobin fraction. Six individuals with SCD recovering from SARS-Cov-2 with biomarker data available both before and for more than 3 months after the infection (179±62 days) were included in the study. Results: IgG levels varied from less than 0.1 to 37, with positive values being defined as IgG > 1. The median estimated half-life of IgG decline was 53 days ranging from 25 to 90 days (the last, for the hospitalized patient). Averaged for IgG positive (IgG+) and IgG negative (IgG-) conditions, combining pre- and post-infection IgG- conditions, values of patient hemoglobin (Hb), FA-WB-VCAM, FA-WB-Psel, and RBC MF cell properties lacked statistical significance (under both a paired t-test and population statistics). Hb levels remained essentially unchanged regardless of the time from infection or IgG status. However, FA-WB-VCAM, FA-WB-Psel, and RBC MF were all significantly elevated after SARS-Cov-2 seroconversion and remained elevated despite declining IgG levels (e.g., Fig. 1). These increases in biomarker values were statistically significant for both FA-WB-VCAM and RBC MF, and were approaching significance for FA-WB-Psel (p<0065). These increases were highly patient-specific with potential return to pe-infection values observed in some cases at about 5-6 months after the infection. A qualitative review of the medical records indicated a new subjective report of fatigue in 5 of 6 patients. Longer observations are required to determine if abnormal blood cell adhesive properties and RBC membrane instability are mechanisms of long-COVID-19 pathophysiology. Conclusions: Whole blood adhesion to both p-selectin and VCAM-1 as well as RBC membrane stability can be significantly impaired in convalescent SARS-Cov-2 patients suggesting an association with long COVID-19. New and emerging treatments that modify whole blood adhesive properties and RBC membrane stability should be investigated for their potential to accelerated recovery from long COVID-19. Health F. A Detailed Study of Patients with Long-Haul COVID: An Analysis of Private Healthcare Claims; White Paper. June 15, 2021 Disclosures Tarasev: Functional Fluidics: Current holder of stock options in a privately-held company. Ferranti: Functional Fluidics: Current holder of stock options in a privately-held company. Allen: Functional Fluidics: Current Employment. Gao: Functional Fluidics: Current Employment. Topping: Functional Fluidics: Current Employment. Ferranti: Functional Fluidics: Current Employment. Makinde-Odesola: Functional Fluidics: Other: conduct research for academic program. Hines: Functional Fluidics: Current holder of stock options in a privately-held company.