Robust inducible gene expression in intracellular Listeria monocytogenes in vivo.

Attenuated strains of the intracellular pathogen Listeria monocytogenes can deliver genetically encoded payloads inside tumor cells. L. monocytogenes preferentially accumulates and propagates inside immune-suppressed tumor microenvironments. To maximize the payload impact in tumors and minimize damage to healthy tissues, it is desirable to induce payload synthesis when bacteria are eliminated from the healthy tissues but are grown to high numbers intratumorally. Here, we have engineered a tightly controlled gene expression system for intracellular L. monocytogenes inducible with a cumin derivative, cumate. Upon cumate addition, expression of a reporter gene is increased in L. monocytogenes growing in vitro by 80-fold, and in intracellular L. monocytogenes in murine tumors by 10-fold. This study demonstrates the feasibility of activating gene expression in intracellular bacteria in live animals using an edible inducer. The system is expected to enhance the efficacy and safety of the attenuated L. monocytogenes strains as antitumor payload delivery bacterial drones.

Intrinsic role of bacterial secretion systems in phylogenetic niche conservation of Bradyrhizobium spp.

Bradyrhizobium is a biologically important bacterial genus. Different Bradyrhizobium strains exhibit distinct niche selection like free living, root nodular and stem nodular. The present in-silico study was undertaken to identify the role of bacterial secretome in the phylogenetic niche conservation (PNC) of Bradyrhizobium sp. Analysis was carried out with the publicly available 19 complete genome assembly and annotation reports. A protocol was developed to screen the secretome related genes using three different database, viz. genome, proteome and gene ortholog. This resulted into 139 orthologs that include type secretion systems (T1SS-T6SS) along with flagella (Flg), type IV pili (T4P) and tight adherence (Tad) systems. Multivariate analysis using bacterial secretome was undertaken to find out the role of these secretion systems in PNC. In free living strains, T3SS, T4SS and T6SS were completely absent. Whereas, in the stem nodulating strains, T3SS and T6SS were absent, but T4SS was found to be present. On the other hand, the T3SS was found to be present only in the root-nodulating strains. The present investigation clearly demonstrated a pattern of PNC based on the distribution of secretion system components. To the best of our knowledge, this is the first report on PNC of Bradyrhizobium using the multivariate analysis of secretome.

Complete Comparison Display (CCD) evaluation of ethanol extracts of Centella asiatica and Withania somnifera shows that they can non-synergistically ameliorate biochemical and behavioural damages in MPTP induced Parkinson's model of mice.

Parkinson's disease remains as one of the most common debilitating neurodegenerative disorders. With the hopes of finding agents that can cure or reduce the pace of progression of the disease, we studied two traditional medicinal plants: Centella asiatica and Withania somnifera that have been explored in some recent studies. In agreement with the previous work on ethanol extracts of these two plants in mice model, we saw an improvement in oxidative stress profile as well as behavioral performance in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induced Parkinson-like symptoms in Balb/c mice. Given the known potential of both the herbal extracts in improving Parkinson-like symptoms, we expected the combination of the two to show better results than either of the two but surprisingly there was no additivity in either oxidative stress or behavioural recovery. In fact, in some assays, the combination performed worse than either of the two individual constituents. This effect of mixtures highlights the need of testing mixtures in supplements market using enthomedicine. The necessity of comparing multiple groups in this study to get most information from the experiments motivated us to design a ladder-like visualization to show comparison with different groups that we call complete comparison display (CCD). In summary, we show the potential of Centella asiatica and Withania somnifera to ameliorate Parkinson's disorder.