Expanding the Genetic Toolbox to Improve Metabolic Engineering in the Industrial Oleaginous Yeast, \u3cem\u3eYarrowia lipolytica\u3c/em\u3e

The oleaginous yeast, Yarrowia lipolytica, is becoming a popular host for industrial biotechnology because of its ability to grow on non-conventional feedstocks and naturally accumulate significant amounts of lipids. With new genome editing technologies, engineering novel pathways to produce lipid-derived oleochemicals has become easier. The goal, however, is to expand the genetic toolbox to improve the efficiency of metabolic engineering such that production capacities could expand from proof-of-concept shake flasks to an industrial scale. Building efficient metabolic circuits require controlling strength and timing of several enzymes in a metabolic pathway. One method to do this is through transcription – using suitable promoters to control expression of genes that code for enzymes. Native promoters have limited application because of complex regulation and non-tunable expression. Engineering hybrid promoters alleviates these issues to obtain predictable and tunable gene expression. In Y. lipolytica, how to design these promoters is not fully understood, resulting in only a handful of engineered promoters to date. In this work, we aim to develop tools for gene expression by investigating promoter architecture and designing tunable systems. In addition to Upstream Activating Sequences (UAS), tuning promoter strength can be achieved by varying sequence in the core promoter, TATA motif, and adjacent proximal sequences. UASs can modulate transcription strength and inducibility, enabling controlled timing of expression. A promoter of the acyl-CoA oxidase 2 (POX2) from the β-oxidation pathway was truncated heuristically to identify oleic acid (OA) UAS sequences. By fusing tandem repeats of the OA UAS elements, tunable yet inducible fatty acid hybrid promoters were engineered. The current approaches to identify novel UAS elements in Y. lipolytica are laborious. Therefore, we investigated DNA accessibility through nucleosome positioning to determine if a relationship between POX2 UASs and DNA accessibility can be inferred. The goal is to eventually apply this approach develop newer hybrid promoters efficiently. Finally, the hybrid fatty acid inducible promoter we developed was used to rationally engineering a Y. lipolytica strain capable of producing high amounts of free fatty acids. By localizing the fatty acyl / fatty aldehyde reductase in the peroxisome, we compartmentalized fatty alcohol production. This strategy led to upwards of 500 mg/L of fatty alcohols produced. It is a promising route to eventually make short to medium chain fatty alcohols in Y. lipolytica by utilizing the native β-oxidation machinery

Bayesian estimation of population proportion in Kim and Warde mixed randomized response technique

In this study, we have developed the Bayesian estimator of the population proportion of a sensitive characteristic when data are obtained through the Randomized Response Technique (RRT) proposed by Kim and Warde (2005). Superiority of the Bayesian estimators is established for a wide range of the values of the population proportion using simple Beta prior information.  It is observed that Bayesian estimators are better than the usual Maximum Likelihood Estimator (MLE) for small as well as moderate samples. The Proposed estimator is also compared with the Warner (1965), Kim and warde (2005) and Kim et al. (2006) estimators

Logit Estimation Using Warner’s Randomized Response Model

A modified hidden logit estimation procedure is presented based on Warner (1965) randomized response model. Monte Carlo simulations explore the behavior of this estimator and compare its performance with the ordinary logits estimator. Warner’s model is more protective and less jeopardizing

Review: Anaerobic Biotechnology for Industrial Wastewater Treatment

There has been the microbiological formation of methane since ages in many diverse habitats such as paddies, marshes, hot springs, benthic deposits, deep ocean trenches, pigs, trees, cattle, termites, iguanas and human beings. Anaerobic digestion has been proved as the most appropriate technique for the treatment of high strength organic effluents. This technique is more reliable and advanced as compared to the conventional water treatment procedures. It uses very less amount of chemicals and treats the wastes in a facile and effective manner and has been considered as an attractive option for effluents treatment. The anaerobic technology causes the decrease of high level of waste materials and different reactors were developed for this particular purpose. It generates best level of fuels used as biogas. The biogas produced in anaerobic digestion burns cleanly and the biogas plants make more energy than they consume to operate, whereas the energy produced by aerobic digestion is very much lower than that produced by anaerobic digestion

Gastric teratoma: A rare benign tumour of neonates

We describe our experience of two neonates with gastric teratoma, one a low-birthweight, premature baby who had a massive, immature teratoma. Complete excision is the appropriate treatment

BETWEEN COMMUNITY AND SECULARISM: THE DAWOODI BOHRAS AND AGENDAS OF 'REFORM' IN INDIA, C. 1915 - 1985

Master'sMASTER OF ART

Phytochemistry of Ziziphus Mauritiana; its Antioxidant and Antimicrobial Potential

Background: Z. mauritiana is a very common and easily available plant all over the world, including Pakistan. It finds a lot of importance due to its nutritional and medicinal value.Methods: Current studies were performed to investigate the phytochemical nature and antioxidant and antimicrobial potential of Z. mauritiana (Lahore, Pakistan). Total phenolic contents in leaves and pulp extracts were identified using a modified Folin-Ciocalteu’s method while total sugars were determined by Lane and Eynon method. Antioxidant activity was determined by DPPH radical-scavenging activity assay using a UV-Visible spectrophotometer at 517 nm. The antimicrobial potential was tested by agar well diffusion method using imipenem as standard drug.Results: The methanolic extracts of leaves and pulp contained tannins, saponins, phlobatannins, alkaloids and flavonoids while steroids were absent in both the samples. The pulp and leave extracts have shown the presence of 57.3% and 37.89% sugar contents, respectively. The concertation of total phenolic contents (TPC) was found higher in pulp extracts as compared to that observed in leaves. The methanolic pulp extract has shown higher antioxidant potential as compared to the leaves extract. However, methanolic leaves extract exhibited higher antibacterial potential as compared to the methanolic pulp extract.Conclusion: The methanolic extracts of Z. Mauritiana pulp and leaves contain many biologically active ingredients and are biologically active against most of the tested bacterial strains. Its pulp and leaves are richer in numerous antioxidants and secondary metabolites. The pulp extract exhibited higher antioxidant potential as compared to the leaves extract.Keywords: Z. Mauritiana; Phytochemicals; Total Phenolic contents; Antibacterial