Genetic manipulation of fermentative metabolism in Chlamydomonas reinhardtii

Photobiological hydrogen production by green algae, such as Chlamydomonas reinhardtii is an attractive approach to generate renewable energy, but is currently not economically viable. It has been suggested that hydrogen yields could potentially be improved by eliminating or down-regulating competing fermentative pathways. However, at present fermentative metabolism is not completely understood in C. reinhardtii, such as the nature of the ill-defined D-lactate dehydrogenase (D-LDH) activity responsible for the production of D-lactate. To characterise the D-LDH activity, a bioinformatics analysis identified a candidate nucleus-encoded D-LDH in the C. reinhardtii genome (Phytozome v9.1 ID: Cre07.g324550), which was predicted to be localised to the chloroplast. The putative protein without its predicted chloroplast transit peptide was overexpressed in Escherichia coli as a C-terminal His6-tagged protein to confirm its function and assess its structure. Enzyme assays confirmed that the protein was an NAD+-dependent D-LDH, favouring the reduction of pyruvate to D-lactate with an estimated Km value of 1.85 ± 0.05 mM and kcat value of 415 ± 18 s-1. Size-exclusion chromatography suggests the holoenzyme was tetrameric with a molecular mass of about 202 kDa. Artificial microRNA technology was used to reduce the amount of D-LDH protein to less than 20% of WT levels. D-lactate was still produced in the mutant either from residual D-LDH activity or from other routes such as from methylglyoxal. Both NMR and HPLC confirmed that the knockdown did not have any substantial impact on dark anaerobic metabolite production except in slightly increasing the pyruvate levels. Additionally, the knockdown did not improve hydrogen yields under sulphur-deprived conditions. To assess the impact of eliminating fermentative pathways on metabolism, a series of mutants was isolated through cell mating, targeting the enzymes D-LDH, pyruvate decarboxylase (PDC3), pyruvate formate lyase (PFL1) and a bifunctional acetaldehyde/alcohol dehydrogenase (ADH1). Dark anaerobic metabolite production in the quadruple mutant confirmed the re-routing of metabolic flux from ethanol and formate towards glycerol and D-lactate. There was also a reduced flux towards acetate production. Pyruvate and glucose levels were found to be elevated in this mutant. Gas chromatography analysis suggested that downregulation of the fermentative pathways did not improve hydrogen production under sulphur-deprived conditions, in part because of reduced cell viability. These mutants are promising tools for future studies probing the metabolism of C. reinhardtii.Open Acces

A comparative application of flood routing models on the rivers Wear and Tees with special reference to the state variable model

An analysis of a number of flood routing methods has been carried out in this study. These methods are namely, the Muskingum-Cunge Method, the Variable Parameter Diffusion Method, the State Variable Kinematic Wave Model, and the state variable modelling of nonlinear Muskingum Model. The Muskingum-Cunge and Variable Parameter Diffusion Methods are recommended for use on British Rivers by the Natural Environment Research Council flood studies report, 1975.In using numerical flood routing model, it is very important to calculate the model parameters. For instance storage routing models require a suitable form of storage-discharge relationship. Past flow records were used for the above calculation. The state Variable Kinematic Wave Model has been applied for routing the flood hydrograph through river reaches. The stage and discharge are computed by a kinematic wave routing technique using the state variable approach in which the one-dimensional differential equations of unsteady flow are solved by state and output equations of the state variable model. The nonlinear Muskingum equation has been solved using the state variable modelling technique. Two parameter estimation techniques namely, Hooke-Jeeves and linear regression, are employed for the calibration of the nonlinear Muskingum model parameters (a, x, and m).The applicability of the flood routing model computer programs to different flood events of different seasons for reaches of both the Rivers Wear and Tees is demonstrated. Discriptions of the geology and hydrological data for reaches of both the Rivers Wear and Tees are given in this study. The computed and observed hydrographs of flood routing models used in this study are compared

Detecting and Locating Signal Leakages from Cable TV Networks – A Case Study

Since the digitalization of terrestrial television, many countries have discontinued television broadcasting in the UHF band. The freed-up frequencies are now available as digital dividends for mobile and fixed wireless access communication networks (MFCN), particularly for 4G/5G and public safety services in broadband called BBPPDR. Since cable TV still uses the UHF band, leakage from cable TV networks is the most common cause of interference in MFCN networks. Insufficient containment of the radio frequency signals transmitted through a cable system results in cable signal leakage. This article investigates the significance of controlling electromagnetic signal leaks from cable TV networks and how they impact authorized and standardized MFCN networks in the digital dividend bands. The periodic drive-test approach to detect and measure electromagnetic leakage from a cable TV system in the 700 MHz band at a site is detailed. The causes of the detected leaks and offered the appropriate procedure to repair them are also discussed. Additionally, the current measures taken in Hungary to address cable television signal leakage in the digital dividend bands are also discussed and alternative strategies for the adopted test drive approach are proposed

Pollution Risk of water Quality on Human and Aquatic Life of Tigris River Reach in Mosul City / North Iraq

Considerable attention is now being paid to uses of rivers and lake for such purposes as domestic, fishing, aquatic life and esthetical enjoyment. Study of water quality for Tigris River reach of Length 24 Km. in Mosul city, North Iraq, was carried out in order to assess their chemical composition  and suitability for human and aquatic life. Laboratory analysis of 15 water samples for five sites within the river reach , were performed in order to obtain the chemical concentration of Ca, Na, Mg, HCO3, SO4, Cl, NO3, TDS and pH. Certain ions may be lethal to human and other aquatic life forms when present at levels near or below the limit give by public water supplies. Copper , zinc and aluminum which are not among the metals for which limits are prescribed for public water supply, are toxic to human and many other species of aquatic life. Concentration of chemical constituents in water samples vary spatially and temporarily due to the reaction with environment, solubility of salts and human activities that find it way to the river reach. The chemical analysis of water samples compared with the standard guideline values as recommended by the World Health Organization (WHO) for human, fisheries and aquatic life. four samples of the right bank side and one sample of site 3 in the left bank side of the river reach are fall within the poor quality type water. While the other samples of the left bank side and the deepest part of the river reach are fall within the high quality type water

Red deer algorithm-based selective harmonic elimination technique for multilevel inverters

This paper proposed a red deer algorithm (RDA)-based selective harmonic elimination (SHE) method for multilevel inverters (MLIs). To eliminate the desired harmonic orders, the optimum switching angles of the MLI have been calculated using the proposed RDA. The calculated switching angles have been applied to the 3-phase cascaded H-bridged 11-level inverter. In addition, the performance of the proposed RDA method was compared with the results of methods such as the Newton-Raphson (NR) method, LSHADE/EpSin technique (LSHADE), whale optimization algorithm (WOA), and particle swarm optimization (PSO) used for the SHE problem in the literature. The results obtained prove that the proposed RDA optimization solves the SHE problems more effectively than other methods. It has also been observed that RDA produces good solutions in different modulation indexes

Bibliometric analysis of Asian Pacific Journal of Tropical Medicine from 2008 to 2019

The purpose of the study is to assess the scientific research productions in Asian Pacific Journal of Tropical Medicine (APJTM) from its first issue up to Dec 2019. We used the Web of Science Core Collection (SCI-EXPANDED, SSCI) to extract the relevant documents. Additionally, the data analysis using ORIGIN PRO 2018, HistCite, bibliometrix R-package, and VOSviewer. Var1.6.6. A total of 2,137 publications of APJTM. A total of 2,136 documents were retrieved, with received 13956 citations, with an average mean 6.63 citations per article, an h-index of 38. The most frequently occurring keywords in this analysis were Malaria, dengue, apoptosis, antioxidant, rate, invasion and anopheles stephesi and inflammation. The study provided the comprehensive and general overview for APJTM journal over its history from the first issue up-to-date. Moreover, the findings provide an insight into the frequency of citations for top-cited articles published in APJTM as well as the quality of the works, journals, trends of publications steering in APJTM

Antibacterial efficacy of some essential oils in combination with locally used disinfectants against clinical and environmental strains of Staphylococcus spp.

Through a period of three months ( October to December, 2014), 37 clinical and environmental Staphylococcus isolates were collected from three different hospitals in Baghdad (Baghdad Teaching Hospital, Fattima-AL-Zahra Hospital for Pediatric and Obstetricand AL-Kindi Teaching Hospital), 25(67.57%) isolates were from clinical specimens and 12(32.43%) isolates were from hospital environment. out of 37 isolates, 28(75.68%) isolates were Coagulase-Negative Staphylococci (CONS) while 9 (24.32%) isolates were Staphylococcus aureus (coagulase-positive staphylococci). Three different disinfectants commonly used in our hospitals were tested to determine the antibacterial activity against Staphylococcus isolates and the result in showed a high level resistance of Staphylococcus isolates to the disinfectants under test when used alone. The result also showed that the concentrated SURFANIOS and Sekulyse disinfectants were more effective on the Staphylococcus isolates under test in comparison to the diluted concentration of those disinfectants. Antibacterial activity of Syzygium aromaticum (cloves oil), Eucalyptus globules (calptus oil) and Rosmarinus officinalis (rosemary oil) was done in different concentrations (100, 50, 25 and 12,25 mg/ml) for each essential oil. The findings revealed that the cloves oil is the only essential oil which had antibacterial activity against Staphylococcus spp.strains in the 100,50and 25 mg/ml concentrations, while the other two essential oils have no antibacterial activity against studied isolates. The antibacterial activity of essential oils in combination with disinfectants against Staphylococci strains were observed using agar well diffusion method and the result showed that the essential oils in combination with disinfectants showed considerably more antibacterial activity than the essential oils and disinfectants alone when compared with them