Biology subjects

Desai, S.

Publications and source records attributed to Desai, S..

41 records · Page 3Linked to original sources

bioRxiv2019

Co-culture of Saccharomyces cerevisiae (VS3) and Pichia stipitis (NCIM 3498) for bioethanol production using concentrated Prosopis juliflora acid hydrolysate

Bioethanol production from lignocellulosic biomass is a viable option for improving energy security and reducing green house emissions. In the present study Prosopis juliflora, an invasive tree found through out India, with total carbohydrate content of 67.4 +/- 6% was selected as lignocellulosic feedstock for bioethanol production. The hydrolysate obtained after biphasic dilute acid hydrolysis contained initial sugar concentration of 18.70 +/- 0.16 g/L and hence to increase the ethanol yield it was concentrated to 33.59 +/- 0.52 g/L (about two-folds) by vacuum distillation. The concentration of sugars, phenols and furans was analyzed before and after concentration process. The concentrated hydrolysate was further detoxified by over liming, neutralization and charcoal treatment and later used for ethanol fermentation by mono- and co culture method. Monoculture of Saccharomyces cerevisiae (VS3) and Pichia stipitis (NCIM 3498) produced 8.52 +/- 0.43 and 4.52 +/- 0.23 g/L of ethanol with 66.21 +/- 3.26% and 60.46 +/- 3.02% of fermentation efficiency, 0.33 +/- 0.02 and 0.31 +/- 0.02 g/g of ethanol yield and 0.24 +/- 0.01 and 0.13 +/- 0.01 g/L/h of productivity, respectively. The co-culture of S. cerevisiae (VS3) and P. stipitis (NCIM 3498) helped to improve all parameters i.e. 10.94 +/- 0.53 g/L of ethanol with fermentation efficiency, ethanol yield and productivity of 83.11 +/- 0.42%, 0.420 +/- 0.01 g/g and 0.30 +/- 0.01 g/L/h, respectively.

bioengineering↗

bioRxiv2019

Zinc Solubilizing Plant Growth Promoting Microbes Produce Zinc Nanoparticles

Strains of Pseudomonas, Bacillus and Azospirillum with plant growth promoting ability were checked for their zinc solubilizing ability. Efficient zinc solubilizers were checked for their ability to produce nano-scale zinc particles. The nanoparticles from the cell-free culture filtrates obtained from these strains were characterized for particle size, Zeta potential and functional groups. Presence of Zn nanoparticles in the bacterial culture filtrate was confirmed by particle distribution and Scanning electron microscope (SEM) analysis. Most properties of nanoparticles are size dependent. Zinc nanoparticles were observed to be spherical in shape and size ranged from 52.0 to 106.0 nm. Zeta potential of the Zn nanoparticles was estimated to understand the stability of the particles. The measured zeta potentials varied from -14.5mV to +179.10 mV indicating high stability and dispersion of the zinc nanoparticles. FTIR peaks at different wave numbers depicted the role of functional groups of proteins in the biosynthesis of Zn nanoparticles. This finding opens a new area of research focusing on microbe-microbe interactions in rhizosphere and plant-microbe interactions at rhizosphere apart from biosynthesis of nanoparticles, which has major applications. To our knowledge, this is the first report of production of nanoparticles as part of nutrient mobilization by plant growth promoting rhizobacteria.

microbiology↗

bioRxiv2019

Seed treatment with chitosan synergizes plant growth promoting ability of Pseudomonas aeruginosa-P17 in sorghum (Sorhum bicolor L.)

Inoculation of crop plants with PGPR has in a large number of investigations resulted in increased plant growth and yield both in the greenhouse and in the field. This plant growth promoting effect of bacteria could be due to net result of synergistic effect of various pgpr traits that they exert in the rhizosphere region of the plant. Four (04) bacterial strain of fluorescent Pseudomonas spp. viz. P1, P17, P22 and P28 were identified previously for their plant growth promoting nature and abiotic stress tolerance and selected further to assess their chitinolytic activity and growth promotion on sorghum in combination with chitosans of low and high degree of acetylation. It was found that P1 has no chitin degrading nature and rest of the three strains have this property. When studied for their ability to grow in presence of chitosans of DA 1.6, 11, 35 and 56% all the strains showed growth in presence of chitosans. Seed bacterization of sorghum seeds with 04 bacterial strains in the presence and absence of chitosans (both low and high DA) and assessment of plant growth promotion after 15 days of sowing showed that P17+DA 56% chitosan combination showed higher growth of seedlings in plant growth chamber with highest root length of 25.9 cm, highest shoot length of 32.1 cm and dry mass of 132.7 mg/ plant. In P17+DA 56% chitosan treated seedlings various defence enzymes and PR-proteins were found to be present in highest quantities as compared to P1 and un-inoculated controls. Since this strain showed highest growth promotion of sorghum seedlings chitin-chitosan modifying enzyme (CCME) of this strain was partially characterized using different proteomic tools and techniques. CCME of P17 had one active polypeptide with a Pi in the range of 3.0-4.0. The digestion pattern of acetylated and deacetylated chitosans showed that P17 enzyme has endochitinase activity. Substrate specificity assay showed that the enzyme had more specificity towards highly acetylated chitosans. Two dimensional PAGE and MS analysis of the protein revealed similarities of this enzyme with protein of Pseudomonas aeruginosa chitinase PA01 strain of GenBank. In conclusion, the study established the option of opening new possibilities for developing bacterial-chitosan (P17+DA 56% chitosan) product for plant growth promotion and induced systemic resistance in sorghum.

microbiology↗

bioRxiv2018

BIN1 recovers tauopathy-induced long-term memory deficits in mice and interacts with Tau through Thr348 phosphorylation

The bridging integrator 1 gene (BIN1) is a major genetic risk factor for Alzheimers disease (AD). In this report, we investigated how BIN1-dependent pathophysiological processes might be associated with Tau. We first generated a cohort of control and transgenic mice either overexpressing human MAPT (TgMAPT) or both human MAPT and BIN1 (TgMAPT;TgBIN1), which we followed-up from 3 to 15 months. In TgMAPT;TgBIN1 mice short-term memory deficits appeared earlier than in TgMAPT mice; however - unlike TgMAPT mice - TgMAPT;TgBIN1 mice did not exhibit any long-term or spatial memory deficits for at least 15 months. After sacrifice of the cohort at 18 months, immunohistochemistry revealed that BIN1 overexpression prevents both Tau mislocalization and somatic inclusion in the hippocampus, where an increase in BIN1-Tau interaction was also observed. We then sought mechanisms controlling the BIN1-Tau interaction. We developed a high-content screening approach to characterize modulators of the BIN1-Tau interaction in an agnostic way (1,126 compounds targeting multiple pathways), and we identified - among others - an inhibitor of Calcineurin, a Ser/Thr phosphatase. We determined that Calcineurin dephosphorylates BIN1 on a Cyclin-dependent kinase phosphorylation site at T348, promoting the open conformation of the neuronal BIN1 isoform. Phosphorylation of this site increases the availability of the BIN1 SH3 domain for Tau interaction, as demonstrated by nuclear magnetic resonance experiments and in primary neurons. Finally, we observed that the levels of the neuronal BIN1 isoform were decreased in AD brains, whereas phospho-BIN1(T348):BIN1 ratio was increased, suggesting a compensatory mechanism. In conclusion, our data support the idea that BIN1 modulates the AD risk through an intricate regulation of its interaction with Tau. Alteration in BIN1 expression or activity may disrupt this regulatory balance with Tau and have direct effects on learning and memory.

neuroscience↗

bioRxiv2017

Soft drug-resistant ovarian cancer cells invade via two distinct mechanisms utilizing myosin IIB

The failure of chemotherapeutic drugs in treatment of various cancers is attributed to the acquisition of drug resistance. However, the invasion mechanisms of drug-resistant cancer cells remains incompletely understood. Here we address this question from a biophysical perspective by mapping the phenotypic alterations in ovarian cancer cells (OCCs) resistant to cisplatin and paclitaxel. We show that cisplatin-resistant (CisR), paclitaxel-resistant (PacR) and dual drug-resistant (i.e., resistant to both drugs) OCCs are softer and more contractile than drug-sensitive cells. Protease inhibition suppresses invasion of CisR cells but not of PacR and dual cells, suggesting protease-dependent mode of invasion in CisR cells and protease-independent mode in PacR and dual cells. Despite these differences, actomyosin contractility, mediated by the RhoA-ROCK2-Myosin IIB signaling pathway regulates both modes of invasion. Myosin IIB modulates matrix metalloproteinase-9 (MMP-9) secretion in CisR cells and nuclear squeezing in PacR and dual cells, thereby highlighting its importance as a potential therapeutic target for treatment of drug-resistant ovarian cancer cells.\n\nFinancial SupportAuthors acknowledge financial support from IIT Bombay Healthcare Initiative, CSIR andDepartment of Biotechnology (Govt. of India) (Grant # BT/PR14658/MED/31/107/2010).AK and BTwere supported by fellowships from UGC and CSIR respectively (Govt. of India).\n\nAuthors declare no competing financial interests\n\nAuthor contributions: AK, PR and SS designed the experiments. AK performed most of the experiments and analyzed the data.BT and SG developed drug resistant cell lines and did RT-PCR. MM performed western blot. AD performed AFM experiments. SD performed gelatin zymography. ABB, PM, AM and AD helped with live cell imaging experiments. AK and SS wrote the manuscript. All authors read and approved the final manuscript.\n\nSummary statement: This study identifies drug-specific differences in the modes of invasion utilized by ovarian cancer cells, and demonstrates the role of myosin IIB in regulating both modes of invasion.

biophysics↗