Overexpression of the Arabidopsis glutathione peroxidase-like 5 gene (AtGPXL5) resulted in altered redox status, plant development and salt tolerance

Plant’s glutathione peroxidase-like (GPXL) enzymes are thiol-based peroxidases catalysing the reduction of H2O2 or hydroperoxides to water or alcohols using reduced glutathione (GSH) or thioredoxin as an electron donor (Navrot et al., 2006). Arabidopsis thaliana possesses eight isoenzymes located in different plant’s organelles and having different roles in redox-dependent processes. Among them, AtGPXL5 is a poorly known plasma membrane-associated enzyme, although its role in salt stress tolerance was suggested (Gao et al. 2014). We have constitutively overexpressed the AtGPXL5 cDNA and investigated the role of AtGPXL5 in response to NaCl treatment and in development. Experiments were performed by using AtGPXL5-overexpressing lines (OX-AtGPXL5) and Atgpxl5 mutant plants. Based on our results, we have made the following observations: 1) 12-day-old Arabidopsis thaliana Atgpxl5 insertional mutants had higher level of superoxide radical anion and total ROS in untreated roots and shoots, respectively compared with Col-0. The higher level of ROS decreased the cells’ vitality in the shoot of Atgpxl5 seedlings even under control condition. After applying 7-day treatment with the concentration of 100 mM NaCl, the O2•− level in the root was elevated further and reached higher level than in the wild type. These indicate that AtGPXL5 might play an important role in the ROS homeostasis and maintaining the cell’s vitality. 2) The antioxidant mechanisms of the 6-week-old plants have altered, especially in the Atgpxl5 mutants compared to OX-AtGPXL5 plants. Several ROS processing enzymes worked in elevated level in Atgpxl5 mutant, but OX-AtGPXL5 plant exhibited similar activity to the Col-0 wild type. The GPOX activity was elevated in the lowest extent in Atgpxl5 plants while GPOX and TPOX enzymes in the AtGPXL5-overexpressing plants worked about on the level of wild type. 3) Under control conditions, significantly lower GSH was found in the Atgpxl5 mutant roots while its amount was elevated in the OX-AtGPXL5 shoot. The applied salt stress caused accumulation of the highest amount of reduced glutathione and the less oxidized form (GSSG) in the AtGPXL5-overexpressing plants among the investigated lines, while the GSSG increased most in the Atgpxl5 roots. The amount of reduced glutathione was higher and the calculated redox potential was more negative in the overexpressed line than in Col-0. The result confirms that AtGPXL5 has function in regulating the redox state, through which they can also influence the growth and development. 4) AtGPXL5 enzymes are required for healthy growth and development of the Arabidopsis thaliana seedlings. Deficiency of AtGPXL5 led to reduce the length of primary roots, biomass, rosette size, convex area, chlorophyll and anthocyanin contents compared to other investigated lines under normal conditions. In the presence of 100 mM NaCl, Atgpxl5 mutant and the Col-0 wild type seeds showed delayed germination, while germination of the OX-AtGPXL5 lines was not inhibited in the presence of 100 mM NaCl. Untreated OX-AtGPXL5 lines exhibited similar phenotype as Col-0, however the overexpressing plants grew better in the presence of 100mM NaCl: they had larger rosettes, larger convex area and lower convex percentage values with higher content of chlorophyll and anthocyanin than that of the wild type and Atgpxl5 plants. The reduced development of the shoots and decreased root length of the Atgpxl5 mutant indicate that this protein has a function even in the normal development

Information analysis of DNA sequences

The problem of differentiating the informational content of coding (exons) and non-coding (introns) regions of a DNA sequence is one of the central problems of genomics. The introns are estimated to be nearly 95% of the DNA and since they do not seem to participate in the process of transcription of amino-acids, they have been termed “junk DNA.” Although it is believed that the non-coding regions in genomes have no role in cell growth and evolution, demonstration that these regions carry useful information would tend to falsify this belief. In this thesis, we consider entropy as a measure of information by modifying the entropy expression to take into account the varying length of these sequences. Exons are usually much shorter in length than introns; therefore the comparison of the entropy values needs to be normalized. A length correction strategy was employed using randomly generated nucleonic base strings built out of the alphabet of the same size as the exons under question. The distance between exons and introns is calculated based on their probability distributions. We found that Zipf’s distribution was not followed by the n-tuples in DNA sequences, and a newly modified power distribution derived from the Zipf’s distribution was found by trial and error that closely modeled the codon frequencies. Correlation and divergence tests were performed. Our analysis shows that introns carry nearly as much of information as exons, disproving the notion that they do not carry any information. The entropy findings of this thesis are likely to be of use in further study of other challenging works like the analysis of symmetry models of the genetic code

Plant Glutathione Peroxidases: Non-Heme Peroxidases with Large Functional Flexibility as a Core Component of ROS-Processing Mechanisms and Signalling

Glutathione peroxidases (GPXs) are non-heme peroxidases catalyzing the reduction of H2O2 or organic hydroperoxides to water or corresponding alcohols using glutathione (GSH) or thioredoxin (TRX) as a reducing agent. In contrast to animal GPXs, the plant enzymes are non-seleno monomeric proteins that generally utilize TRX more effectively than GSH but can be a putative link between the two main redox systems. Because of the substantial differences compared to non-plant GPXs, use of the GPX-like (GPXL) name was suggested for Arabidopsis enzymes. GPX(L)s not only can protect cells from stress-induced oxidative damages but are crucial components of plant development and growth. Due to fine-tuning the H2O2 metabolism and redox homeostasis, they are involved in the whole life cycle even under normal growth conditions. Significantly new mechanisms were discovered related to their transcriptional, post-transcriptional and post-translational modifications by describing gene regulatory networks, interacting microRNA families, or identifying Lys decrotonylation in enzyme activation. Their involvement in epigenetic mechanisms was evidenced. Detailed genetic, evolutionary, and bio-chemical characterization, and comparison of the main functions of GPXs, demonstrated their species-specific roles. The multisided involvement of GPX(L)s in the regulation of the entire plant life ensure that their significance will be more widely recognized and applied in the future

Plants in Microgravity: Molecular and Technological Perspectives

Plants are vital components of our ecosystem for a balanced life here on Earth, as a source of both food and oxygen for survival. Recent space exploration has extended the field of plant biology, allowing for future studies on life support farming on distant planets. This exploration will utilize life support technologies for long-term human space flights and settlements. Such longer space missions will depend on the supply of clean air, food, and proper waste management. The ubiquitous force of gravity is known to impact plant growth and development. Despite this, we still have limited knowledge about how plants can sense and adapt to microgravity in space. Thus, the ability of plants to survive in microgravity in space settings becomes an intriguing topic to be investigated in detail. The new knowledge could be applied to provide food for astronaut missions to space and could also teach us more about how plants can adapt to unique environments. Here, we briefly review and discuss the current knowledge about plant gravity-sensing mechanisms and the experimental possibilities to research microgravity-effects on plants either on the Earth or in orbit

Capturing planar shapes by approximating their outlines

AbstractA non-deterministic evolutionary approach for approximating the outlines of planar shapes has been developed. Non-uniform Rational B-splines (NURBS) have been utilized as an underlying approximation curve scheme. Simulated Annealing heuristic is used as an evolutionary methodology. In addition to independent studies of the optimization of weight and knot parameters of the NURBS, a separate scheme has also been developed for the optimization of weights and knots simultaneously. The optimized NURBS models have been fitted over the contour data of the planar shapes for the ultimate and automatic output. The output results are visually pleasing with respect to the threshold provided by the user. A web-based system has also been developed for the effective and worldwide utilization. The objective of this system is to provide the facility to visualize the output to the whole world through internet by providing the freedom to the user for various desired input parameters setting in the algorithm designed

EFFECT OF ZANJABĪL (ZINGIBER OFFICINALE) IN NON-ALCOHOLIC FATTY LIVER DISEASE- A RANDOMIZED CONTROLLED TRIAL

Non Alcoholic Fatty Liver Disease (NAFLD) is a reversible condition of the liver, wherein large vacuoles of triglyceride fat accumulates in liver cells via the process of steatosis, despite any evidence of excessive alcohol consumption. In view of present scenario of high prevalence and limited treatment options, this study was conducted to assess the effect of Murabba-i- Zanjabīl in NAFLD. Present study was designed as a randomized placebo controlled trial with 30 patients in test group and 10 patients in control group. Participants in test group were administered with Murabba-i- Zanjabīl, 5 gm twice daily, 30 minutes before food for 45 days and those in control group were given 1 capsule of 500 mg each containing wheat flour twice daily, 30 minutes before food for 45 days. All the participants were asked to follow up at every 15 days for assessment of subjective parameters. Objective parameter was assessed before and after the trial period. On statistical analysis the test formulation showed significant reduction in scores (p<0.05) for most of the parameters on both inter and intra group analysis, while the reduction in control group was not found to be statistically significant (p.0.05). This study lays out that Murabbā-i Zanjabīl in a dose of 5gm twice daily given for 45 days is more effective than placebo in treating NAFLD. There was no adverse effect reported during the trial. It was thus concluded that Murabbā-i Zanjabīl is effective and safe in therapeutic management of NAFLD

Crosstalk between the Arabidopsis Glutathione Peroxidase-Like 5 Isoenzyme (AtGPXL5) and Ethylene

Glutathione peroxidases (GPXs) are important antioxidant enzymes in animals. Plants contain GPX-like (GPXL) enzymes, which-in contrast to GPXs-contain cysteine in their active site instead of selenocysteine. Although several studies proved their importance in development and stress responses, their interaction with ethylene (ET) signalling is not known. Our aim was to investigate the involvement of AtGPXL5 in ET biosynthesis and/or signalling using Atgpxl5 mutant and AtGPXL5 cDNA-overexpressing (OX-AtGPXL5) lines. Four-day-old dark-grown Atgpxl5 seedlings had shorter hypocotyls and primary roots, while OX-AtGPXL5 seedlings exhibited a similar phenotype as wild type under normal conditions. Six-week-old OX-AtGPXL5 plants contained less H2O2 and malondialdehyde, but higher polyamine and similar ascorbate- and glutathione contents and redox potential (E-GSH) than the Col-0. One-day treatment with the ET-precursor 1-aminocyclopropane-1-carboxylic acid (ACC) induced the activity of glutathione- and thioredoxin peroxidases and some other ROS-processing enzymes. In the Atgpxl5 mutants, the E-GSH became more oxidised; parallelly, it produced more ethylene after the ACC treatment than other genotypes. Although the enhanced ET evolution measured in the Atgpxl5 mutant can be the result of the increased ROS level, the altered expression pattern of ET-related genes both in the Atgpxl5 and OX-AtGPXL5 plants suggests the interplay between AtGPXL5 and ethylene signalling