Biology subjects

Rehman, M. U.

Publications and source records attributed to Rehman, M. U..

3 recordsLinked to original sources

bioRxiv2026

Effect of Jasmonic Acid on Chlorophyll Content in Wheat (Triticum aestivum L.) Plants Infested with Russian Wheat Aphid (Diuraphis noxia)

Russian wheat aphid (Diuraphis noxia Homoptera; Aphididae) is a major pest that significantly reduces chlorophyll content and photosynthetic capacity in wheat (Triticum aestivum L.), leading to substantial crop yield losses. Jasmonic acid (JA) is a plant signaling molecule known to activate defense mechanisms against herbivorous insects. This study examined the effectiveness of exogenous jasmonic acid application in maintaining chlorophyll content during Russian wheat aphid infestation. A pot experiment was conducted with four treatments: control (no treatment), aphid infestation only, jasmonic acid application only, and jasmonic acid with aphid infestation. Results demonstrated that aphid infestation significantly reduced chlorophyll a (F = 42.565, P = 0.0001), chlorophyll b (F = 52.565, P = 0.0001), and total chlorophyll (F = 32.565, P = 0.0002) contents compared to healthy plants. Jasmonic acid treatment at 2 mM concentration effectively preserved all forms of chlorophyll, significantly counteracting aphid-induced chlorophyll depletion (P < 0.01). The protective effect of jasmonic acid was evident through the statistically significant interaction between aphid stress and JA application for all chlorophyll parameters. These findings suggest that foliar application of jasmonic acid can serve as an effective strategy to maintain photosynthetic capacity and plant vigor under Russian wheat aphid attack, thereby contributing to sustainable crop management and improved wheat production.

plant biology↗

bioRxiv2026

Antibacterial activity against Escherichia coli: A proof-of-concept study of colloidally aggregated silver nanoparticles with experimental evidence

The emergence of antimicrobial resistance has been rapid, necessitating the development of alternative therapeutic approaches beyond traditional antibiotics. In this proof-of-concept study, we examined the antibacterial activity of citrate-stabilized, colloidally aggregated silver nanoparticles (AgNPs) against Escherichia coli by combining physicochemical characterization with experimental antibacterial testing The synthesis of silver nanoparticles was done through a modified thermal citrate reduction protocol, and UV-visible spectroscopy, dynamic light scattering (DLS), and zeta potential were used to characterize the nanoparticles. Spectroscopy analysis showed a clear surface plasmon resonance peak at 310-320 nm, indicating the formation of nanoparticles. DLS measurements showed that the dominant hydrodynamic diameter was around 250-270 nm, which is indicative of controlled colloidal aggregation, and near-neutral values of zeta potential indicated steric stabilization of the nanoparticle clusters. Agar tests demonstrated a clear zone of inhibition, and broth cultures showed a lower turbidity and slower bacterial growth with AgNPs. The above findings suggest that nanoparticles that are colloidally aggregated maintain a significant antimicrobial activity even though the surface area is lower than that of monodispersed systems. Mechanistically, the observed antibacterial effect can be explained by a multi-modal effect through direct membrane disruption, localized release of silver ions, and the induction of oxidative stress pathways in bacterial cells. The aggregated form could also help to increase the nanoparticle cell interactions through the provision of multivalent contact points of nanoparticles, and thus the antibacterial efficacy. Controlled colloidal aggregation of AgNPs is a promising approach to the development of effective and possibly more stable antimicrobial agents. These results indicate the possibilities of aggregated nanoparticle systems in fighting drug-resistant pathogens and a basis on future studies of its clinical use.

microbiology↗

bioRxiv2024

Efficient De Novo Assembly and Recovery of Microbial Genomes from Complex Metagenomes Using a Reduced Set of k-mers

In recent years, the analysis of metagenomic data to recover unculturable microbes has revolutionized microbial genomics by rapidly expanding the reference genome catalog. Central to this, are the computational approaches of de novo assembly and genome binning that enable large-scale reference-independent recovery of microbial genomes from the metagenomic sequencing data. Despite the advancements in bioinformatics approaches to address the computational challenges inherent to these tasks, the limitation of computational resources continues to be a significant barrier to harvesting the full potential of these techniques. Consequently, there is a stressed need to devise strategies involving the fine-tuning of the employed parameters for the effective utilization of the available metagenomic tools. As most of the available metagenome assembly tools are based on the de Bruijn graph framework that relies on a parameter k, selecting an appropriate subset of k-mers has become a common approach in bioinformatics for efficient computations. In this study, we propose a reduced set of k-mers, optimized to strike a balance between computational efficiency and the quality of the high- and low-complexity metagenome assemblies. Utilizing this set of k-mers with MEGAHIT reduces the metagenome assembly time by half compared to the default set, thus greatly reducing the associated computational cost. In addition, it also brings the promise to improve large-scale genome binning studies that adopt this set in the future as we observed an increase in the total number of the recovered genomes as well as obtained higher proportions of high- and medium-quality genomes recovered from the reduced k-mers-based metagenome assemblies.

bioinformatics↗