Effect of Cl- and Na+ ratios in nutrient solutions on tomato (Solanum lycopersicum L.) yield in a hydroponic system

Intensive tomato (Solanum lycopersicum L.) production in coastal areas of Sinaloa is exposed to significant amounts of Cl and Na deposited by sea breezes and irrigation water, which affects the yield of this vegetable. The aim of this study was to evaluate three percentage ratios of Cl-/anions (25/100, 50/100 and 75/100) and three percentage ratios of Na+/cations (25/100, 50/100 and 75/100) in the nutrient solution on mineral composition, dry matter production and yield of tomato. The experimental design was completely randomized with a 32 factorial arrangement and four replications. Analysis of variance and mean comparisons were performed (Tukey, P ≤ 0.05). Cl and Na concentrations in tomato leaves, stems and fruits increased significantly with increasing ratios of Cl-/anions and Na+/cations in the nutrient solution. The 75/100 Cl-/anions ratio reduced (P ≤ 0.05) the Ca concentration in leaves, while the 75/100 Na+/cations ratio decreased (P ≤ 0.05) K concentrations in leaves and stems. Both ratios reduced aerial dry biomass (48 and 25.8 %, respectively) and tomato yield (50.8 and 45.7 %, respectively). The results indicate that tomato plants grown with the 75/100 percentage ratio of Cl-/anions or the 75/100 percentage ratio of Na+/ cations absorb excessive amounts of Cl or Na, which causes ionic imbalance (especially of K+ and Ca2+) and affects dry matter production and yield.

Salinity tolerance mechanisms and their breeding implications

Background The era of first green revolution brought about by the application of chemical fertilizers surely led to the explosion of food grains, but left behind the notable problem of salinity. Continuous application of these fertilizers coupled with fertilizer-responsive crops make the country self-reliant, but continuous deposition of these led to altered the water potential and thus negatively affecting the proper plant functioning from germination to seed setting. Main body Increased concentration of anion and cations and their accumulation and distribution cause cellular toxicity and ionic imbalance. Plants respond to salinity stress by any one of two mechanisms, viz., escape or tolerate, by either limiting their entry via root system or controlling their distribution and storage. However, the understanding of tolerance mechanism at the physiological, biochemical, and molecular levels will provide an insight for the identification of related genes and their introgression to make the crop more resilient against salinity stress. Short conclusion Novel emerging approaches of plant breeding and biotechnologies such as genome-wide association studies, mutational breeding, marker-assisted breeding, double haploid production, hyperspectral imaging, and CRISPR/Cas serve as engineering tools for dissecting the in-depth physiological mechanisms. These techniques have well-established implications to understand plants’ adaptions to develop more tolerant varieties and lower the energy expenditure in response to stress and, constitutively fulfill the void that would have led to growth resistance and yield penalty.

Melatonin Modulates Plant Tolerance to Heavy Metal Stress: Morphological Responses to Molecular Mechanisms

Heavy metal toxicity is one of the most devastating abiotic stresses. Heavy metals cause serious damage to plant growth and productivity, which is a major problem for sustainable agriculture. It adversely affects plant molecular physiology and biochemistry by generating osmotic stress, ionic imbalance, oxidative stress, membrane disorganization, cellular toxicity, and metabolic homeostasis. To improve and stimulate plant tolerance to heavy metal stress, the application of biostimulants can be an effective approach without threatening the ecosystem. Melatonin (N-acetyl-5-methoxytryptamine), a biostimulator, plant growth regulator, and antioxidant, promotes plant tolerance to heavy metal stress by improving redox and nutrient homeostasis, osmotic balance, and primary and secondary metabolism. It is important to perceive the complete and detailed regulatory mechanisms of exogenous and endogenous melatonin-mediated heavy metal-toxicity mitigation in plants to identify potential research gaps that should be addressed in the future. This review provides a novel insight to understand the multifunctional role of melatonin in reducing heavy metal stress and the underlying molecular mechanisms.

Multifarious Biomarker Approach Elucidate Stocking Density Mediated Stress, Modulates Growth Attributes in Cage Reared Rohu, Labeo Rohita (Hamilton)

The present study was conducted for 240 days to evaluate the effects of stocking density based on growth attributes, digestive enzymes, muscular composition, biochemical and physiological responses of Labeo rohita fingerlings in tropical inland open water cages. L. rohita (30.35±1.08 g) were randomly distributed into three treatments, namely low stocking density, LSD (10 m− 3), medium stocking density, MSD (20 m− 3) and high stocking density, HSD (30 m− 3) in triplicates. Fish were fed twice daily with CIFRI CAGEGROW® floating feed (crude protein-28%, crude fat-4%). Fish growth and feed efficiency was higher (P<0.05) in LSD, however MSD registered higher yield. Amylase and protease activity reduced whereas lipase activity increased with increasing stocking density. Muscle crude protein and crude fat formed inverse correlation. The fillet quality deteriorated at higher stocking densities based on Muscle pH, drip loss and frozen leakage rate. The stress biomarkers level (glucose, cortisol, superoxide dismutase and catalase) increased in serum under crowding condition. Glutamate oxaloacetate transaminase and glutamate pyruvate transaminase in serum was significantly increased in HSD. Serum protein level decreased with increase in stocking densities. Body ionic imbalance (Na+, Cl− and K+) observed under crowding stress. Based on growth attributes and multiple biomarker responses, L. rohita @ 10 m− 3 found to be optimum density for inland open water cage culture.

Arbuscular mycorrhizal symbioses alleviating salt stress in maize is associated with a decline in root-to-leaf gradient of Na+/K+ ratio

Background Inoculation of arbuscular mycorrhizal (AM) fungi has the potential to alleviate salt stress in host plants through the mitigation of ionic imbalance. However, inoculation effects vary, and the underlying mechanisms remain unclear. Two maize genotypes (JD52, salt-tolerant with large root system, and FSY1, salt-sensitive with small root system) inoculated with or without AM fungus Funneliformis mosseae were grown in pots containing soil amended with 0 or 100 mM NaCl (incrementally added 32 days after sowing, DAS) in a greenhouse. Plants were assessed 59 DAS for plant growth, tissue Na+ and K+ contents, the expression of plant transporter genes responsible for Na+ and/or K+ uptake, translocation or compartmentation, and chloroplast ultrastructure alterations. Results Under 100 mM NaCl, AM plants of both genotypes grew better with denser root systems than non-AM plants. Relative to non-AM plants, the accumulation of Na+ and K+ was decreased in AM plant shoots but increased in AM roots with a decrease in the shoot: root Na+ ratio particularly in FSY1, accompanied by differential regulation of ion transporter genes (i.e., ZmSOS1, ZmHKT1, and ZmNHX). This induced a relatively higher Na+ efflux (recirculating) rate than K+ in AM shoots while the converse outcoming (higher Na+ influx rate than K+) in AM roots. The higher K+: Na+ ratio in AM shoots contributed to the maintenance of structural and functional integrity of chloroplasts in mesophyll cells. Conclusion AM symbiosis improved maize salt tolerance by accelerating Na+ shoot-to-root translocation rate and mediating Na+/K+ distribution between shoots and roots.

Viroporin activity of SARS-CoV-2 Orf3a and Envelope protein impacts viral pathogenicity

COVID-19 is caused by SARS-CoV-2 which has affected nearly 220 million people worldwide and death toll close to 5 million as of present day. The approved vaccines are lifesaving yet temporary solutions to such a devastating pandemic. Viroporins are important players of the viral life cycle of SARS-Cov-2 and one of the primary determinants of its pathogenesis. We studied the two prominent viroporins of SARS-CoV-2 (i) Orf3a and (ii) Envelope (E) protein from a structural point of view. Orf3a has several hotspots of mutations which has been reported in SARS-CoV-2 with respect to SARS-CoV-1. Mutations in SARS-CoV-2 Orf3a channel forming residues enhances the formation of a prominent the inter-subunit channel, which was not present in the SARS-CoV-1 Orf3a. This enhanced structural feature can be correlated with higher channelling activity in SARS-CoV-2 than in SARS-CoV-1. On the other hand, E protein is one of the most conserved protein among the SARS-CoV proteome. We found that the water molecules form networks of electrostatic interactions with the polar residues in the E protein putative wetted condition while no water channel formation was observed in the putative dewetted condition. This aqueous medium mediates the non-selective translocation of cations thus affecting the ionic homeostasis of the host cellular compartments. This ionic imbalance leads to increased inflammatory response in the host cell. Our results shed light into the mechanism of viroporin action, which can be leveraged for the development of antiviral therapeutics. Furthermore, our results corroborate with previously published transcriptomic data from COVID-19 infected lung alveolar cells where inflammatory responses and molecular regulators directly impacted by ion channelling were upregulated. These observations overlap with transcript upregulation observed in diseases having acute lung injury, pulmonary fibrosis and Acute Respiratory Distress Syndrome (ARDS).

Differential impact of Kv8.2 loss on rod and cone signaling and degeneration.

The voltage-gated potassium channel responsible for controlling photoreceptor signaling is a heteromeric complex of Kv2.1 subunits with a regulatory Kv8.2 subunit. Kv2.1/Kv8.2 channels are localized to the photoreceptor inner segment and carry IKx, largely responsible for setting the photoreceptor resting membrane potential. Mutations in Kv8.2 result in childhood-onset Cone Dystrophy with Supernormal Rod Response (CDSRR). We generated a Kv8.2 knockout (KO) mouse and examined retinal signaling and photoreceptor degeneration to gain deeper insight into the complex phenotypes of this disease. Using electroretinograms we show that there is a tradeoff between delayed or reduced signaling from rods depending on the intensity of the light stimulus, consistent with reduced capacity for light-evoked changes in membrane potential. The delayed response was not seen ex vivo where extracellular potassium levels are the same, so we conclude the in vivo alteration is influenced by ionic imbalance. We observed mild retinal degeneration. Signaling from cones was reduced but there was no loss of cone density. Loss of Kv8.2 altered responses to flickering light with responses attenuated at high frequencies and altered in shape at low frequencies. The Kv8.2 KO line on an all-cone retina background had reduced cone signaling associated with degeneration. We conclude that Kv8.2 is required by rods and cones for responding to dynamic changes in lighting. The timing and cell type affected by degeneration is different in the mouse and human but there is a window of time in both for therapeutic intervention.

Respiratory profile and gill histopathology of Carassius auratus exposed to different salinity concentrations

The aim of this study was to evaluate the chronic salinity tolerance of Carassius auratus and the effects on blood parameters, gill morphology, and survival. In the first test, nine different concentrations (0.0, 0.5, 1.0, 2.5, 5.0, 10, 15, 20, and 25 g L-1) of NaCl were used with nine repetitions for 96 h. The survival of fish subjected to 15 g L-1 NaCl was 4 h, and 5 min at a concentration of 25 g L-1. The mortality of fish with 15 g L-1 NaCl was 100%. Morphological analyses of the gills showed hyperplasia of the coated cells in the interlamellar space and hypersecretion of mucus in fish exposed to 10 g L-1 of NaCl. At concentrations of 20 and 25 g L-1, necrosis of the support collagen caused the cells to detach from the lamellar structure mucosa. In the chronic test, two concentrations were used, with four replications containing nine fish in each aquarium for a period of 21 days. Blood samples and gills from the fish were collected, and it was observed that the fish showed a decrease in the concentration of bicarbonate (NaHCO3) in the blood, indicating hypernatremia. Acute exposure of C. auratus to sodium chloride (NaCl) should be at a maximum of 10 g L-1 of NaCl, after which level there would be a loss in animal performance and/or mortality. Chronic exposure to 5 g L-1 of NaCl promotes acidemia, ionic imbalance, and pathological changes in the gills; therefore, it is not recommended.

Neuroprotective Phytochemicals in Experimental Ischemic Stroke: Mechanisms and Potential Clinical Applications

Ischemic stroke is a challenging disease with high mortality and disability rates, causing a great economic and social burden worldwide. During ischemic stroke, ionic imbalance and excitotoxicity, oxidative stress, and inflammation are developed in a relatively certain order, which then activate the cell death pathways directly or indirectly via the promotion of organelle dysfunction. Neuroprotection, a therapy that is aimed at inhibiting this damaging cascade, is therefore an important therapeutic strategy for ischemic stroke. Notably, phytochemicals showed great neuroprotective potential in preclinical research via various strategies including modulation of calcium levels and antiexcitotoxicity, antioxidation, anti-inflammation and BBB protection, mitochondrial protection and antiapoptosis, autophagy/mitophagy regulation, and regulation of neurotrophin release. In this review, we summarize the research works that report the neuroprotective activity of phytochemicals in the past 10 years and discuss the neuroprotective mechanisms and potential clinical applications of 148 phytochemicals that belong to the categories of flavonoids, stilbenoids, other phenols, terpenoids, and alkaloids. Among them, scutellarin, pinocembrin, puerarin, hydroxysafflor yellow A, salvianolic acids, rosmarinic acid, borneol, bilobalide, ginkgolides, ginsenoside Rd, and vinpocetine show great potential in clinical ischemic stroke treatment. This review will serve as a powerful reference for the screening of phytochemicals with potential clinical applications in ischemic stroke or the synthesis of new neuroprotective agents that take phytochemicals as leading compounds.

Time Dependent Impact of Reactive Oxidants on Seminal Attributes of Murrah Bull during Cryopreservation and Storage

Background: Cryopreservation is an invaluable technique yet it is also known to be detrimental to sperm function and fertility due to cryo-injury and concomitant generation of reactive oxidants. During laboratory manipulation for the cryopreservation and freeze-thaw process, spermatozoa undergo osmotic stress, ionic imbalance, metabolic decoupling, membrane phase transition, destabilization of the cytoskeleton and antioxidant depletion which communally hampers the semen quality.Methods: With the aim of determining implications of cryopreservation and storage, semen samples were collected by artificial vagina technique from 12 Murrah bulls and subsequently examined at 0 hour (before cryopreservation) and at 24 hour, 1 month and 2 month of storage for various seminal attributes. Simultaneously seminal plasma was separated and preserved at -20oC till the analysis of biochemical indicators of semen quality viz., nitric oxide (NO), total antioxidant quantity (TAC) and lipid peroxidation status (TBARS). Result: A sharp reduction (p less than 0.01) in the semen quality was observed only at 24 h after cryopreservation except for viability. Significant reduction (p less than 0.05) in viable counts was observed up to 1 month interval. The capacitated sperm percentage was greater (p less than 0.01) in the cryopreserved semen as compared to fresh ejaculate. The mean ± SE levels of NO (μmol/L), TAC and TBARS (Units/ml) was 2.31±0.27, 0.73±0.04 and 1.11±0.16 respectively in seminal plasma of neat semen stored at -20oC, while the values in the extended seminal plasma after cryopreservation was 2.37±0.31, 0.44±0.03 and 0.65±0.03 respectively. So it can be inferred that most of the damage encountered by spermatozoa is during the initial period of freezing, but the damage associated by various stressors cannot be ignored.