Actinomycetes - The Repertoire of Diverse Bioactive Chemical Molecules: From Structures to Antibiotics.

The urgent need for novel antibiotics in the face of escalating global antimicrobial resistance necessitates innovative approaches to identify bioactive compounds. Actinomycetes, renowned for their prolific production of antimicrobial agents, stand as a cornerstone in this pursuit. Their diverse metabolites exhibit multifaceted bioactivities, including potent antituberculosis, anticancer, immunomodulatory, immuno-protective, antidiabetic, etc. Though terrestrial sources have been exploited significantly, contemporary developments in the field of antimicrobial drug discovery have put marine actinomycetes in a prominent light as a promising and relatively unexplored source of novel bioactive molecules. This is further boosted by post-genomic era advances like bioinformatics-based secretome analysis and reverse engineering that have totally revitalized actinomycetes antibiotic research. This review highlights actinomycetes-based chemically diverse scaffolds and clinically validated antibiotics along with the enduring significance of actinomycetes from untouched ecosystems, especially with recent advanced techniques in the quest for next-generation antimicrobials.

Deciphering Tuberculous Meningitis: From Clinical Challenges to Novel Models and Pathogenic Pathways.

During and after the COVID-19 pandemic,Tuberculosis (TB) has reestablished with higher figures due to interruptions in the Directly Observed Treatment Short course (DOTS) despite underreporting. The rising consequences would have extended to extra-pulmonary forms of TB as well, including Tuberculous Meningitis (TBM). Considering the fact that TBM is the most dangerous and worst form of TB, we found the need to scan the literature to highlight various aspects of TBM. Epidemiology of TBM is proportionally less frightening, but the consequent mortalities and morbidities are more alarming than pulmonary TB. Here, we address critical research gaps in Tuberculous Meningitis that warrant further investigations. The highlighted aspects encompass a comprehensive understanding of TBM's clinical presentation and improved diagnostic tools for timely detection, the exploration of innovative chemotherapies and surgical interventions, the unraveling of the role of the blood-brain barrier in disease onset, investigating of the contributions of various brain cells to TBM development, deciphering the complex inflammatory response, exploring the involvement of Matrix Metalloproteinases in tissue damage, delving into host-pathogen genetics influencing susceptibility, utilizing robust in-vivo and in-vitro models for mechanistic insights, and more importantly between TBM and SARS-COVID-19 are discussed. Addressing these gaps will substantially advance our understanding of TBM's complex pathogenesis, contributing to more effective diagnostic, therapeutic, and preventive strategies against this debilitating disease.

Isolation of high-quality RNA for high throughput applications from secondary metabolite-rich Crocus sativus L.

OBJECTIVE: Isolating high-quality RNA is a basic requirement while performing high throughput sequencing, microarray, and various other molecular investigations. However, it has been quite challenging to isolate RNA with absolute purity from plants like Crocus sativus that are rich in secondary metabolites, polysaccharides, and other interfering compounds which often irreversibly co-precipitate with the RNA. While many methods have been proposed for RNA extraction including CTAB, TriZol, and SDS-based methods, which invariably yield less and poor quality RNA and hence it necessitated the isolation of high-quality RNA suitable for high throughput applications. RESULTS: In the present study we made certain adjustments to the available protocols including modifications in the extraction buffer itself and the procedure employed. Our method led to the isolation of clear and non-dispersive total RNA with an RNA Integrity Number (RIN) value greater than 7.5. The quality of the RNA was further assessed by qPCR-based amplification of mRNA and mature miRNAs such as Cs-MIR166c and Cs-MIR396a.

Pyramiding ascorbate-glutathione pathway in Lycopersicum esculentum confers tolerance to drought and salinity stress.

KEY MESSAGE: Stacking Glutathione-Ascorbate pathway genes (PgSOD, PgAPX, PgGR, PgDHAR and PgMDHAR) under stress inducible promoter RD29A imparts significant tolerance to drought and salinity stress in Solanum lycopersicum. Although the exposure of plants to different environmental stresses results in overproduction of reactive oxygen species (ROS), many plants have developed some unique systems to alleviate the ROS production and mitigate its deleterious effect. One of the key pathways that gets activated in plants is ascorbate glutathione (AsA-GSH) pathway. To demonstrate the effect of this pathway in tomato, we developed the AsA-GSH overexpression lines by stacking the genes of the AsA-GSH pathway genes isolated from Pennisetum glaucoma (Pg) including PgSOD, PgAPX, PgGR, PgDHAR and PgMDHAR under stress inducible promoter RD29A. The overexpression lines have an improved germination and seedling growth with concomitant elevation in the survival rate. The exposure of transgenic seedlings to varying stress regiments exhibited escalation in the antioxidant enzyme activity and lesser membrane damage as reflected by decreased electrolytic leakage and little accumulation of malondialdehyde and H2O2. Furthermore, the transgenic lines accumulated high levels of osmoprotectants with increase in the relative water content. The increased photosynthetic activity and enhanced gaseous exchange parameters further confirmed the enhanced tolerance of AsA-GSH overexpression lines. We concluded that pyramiding of AsA-GSH pathway genes is an effective strategy for developing stress resistant crops.

Ectopic expression of a novel cold-resistance protein 1 from Brassica oleracea promotes tolerance to chilling stress in transgenic tomato.

Cold stress is considered as one of the major environmental factors that adversely affects the plant growth and distribution. Therefore, there arises an immediate need to cultivate effective strategies aimed at developing stress-tolerant crops that would boost the production and minimise the risks associated with cold stress. In this study, a novel cold-responsive protein1 (BoCRP1) isolated from Brassica oleracea was ectopically expressed in a cold susceptible tomato genotype Shalimar 1 and its function was investigated in response to chilling stress. BoCRP1 was constitutively expressed in all the tissues of B. oleracea including leaf, root and stem. However, its expression was found to be significantly increased in response to cold stress. Moreover, transgenic tomato plants expressing BoCRP1 exhibited increased tolerance to chilling stress (4 °C) with an overall improved rate of seed germination, increased root length, reduced membrane damage and increased accumulation of osmoprotectants. Furthermore, we observed increased transcript levels of stress responsive genes and enhanced accumulation of reactive oxygen species scavenging enzymes in transgenic plants on exposure to chilling stress. Taken together, these results strongly suggest that BoCRP1 is a promising candidate gene to improve the cold stress tolerance in tomato.

Promoting the accumulation of scopolamine and hyoscyamine in Hyoscyamus niger L. through EMS based mutagenesis.

The overexploitation of medicinal plants is depleting gene pool at an alarming rate. In this scenario inducing the genetic variability through targeted mutations could be beneficial in generating varieties with increased content of active compounds. The present study aimed to develop a reproducible protocol for in vitro multiplication and mutagenesis of Hyoscyamus niger targeting putrescine N-methyltransferase (PMT) and 6ß-hydroxy hyoscyamine (H6H) genes of alkaloid biosynthetic pathway. In vitro raised callus were treated with different concentrations (0.01% - 0.1%) of Ethyl Methane Sulfonate (EMS). Emerging multiple shoots and roots were obtained on the MS media supplemented with cytokinins and auxins. Significant effects on morphological characteristics were observed following exposure to different concentrations of EMS. EMS at a concentration of 0.03% was seen to be effective in enhancing the average shoot and root number from 14.5±0.30 to 22.2 ±0.77 and 7.2±0.12 to 8.8±0.72, respectively. The lethal dose (LD50) dose was calculated at 0.08% EMS. The results depicted that EMS has an intense effect on PMT and H6H gene expression and metabolite accumulation. The transcripts of PMT and H6H were significantly upregulated at 0.03-0.05% EMS compared to control. EMS treated explants showed increased accumulation of scopolamine (0.639 µg/g) and hyoscyamine (0.0344µg/g) compared to untreated.