Molecular Characterization of Three Novel Phospholipase A2 Proteins from the Venom of Atheris chlorechis, Atheris nitschei and Atheris squamigera

Secretory phospholipase A2 (sPLA2) is known as a major component of snake venoms and displays higher-order catalytic hydrolysis functions as well as a wide range of pathological effects. Atheris is not a notoriously dangerous genus of snakes although there are some reports of fatal cases after envenomation due to the effects of coagulation disturbances and hemorrhaging. Molecular characterization of Atheris venom enzymes is incomplete and there are only a few reports in the literature. Here, we report, for the first time, the cloning and characterization of three novel cDNAs encoding phospholipase A2 precursors (one each) from the venoms of the Western bush viper (Atheris chlorechis), the Great Lakes bush viper (Atheris nitschei) and the Variable bush viper (Atheris squamigera), using a “shotgun cloning” strategy. Open-reading frames of respective cloned cDNAs contained putative 16 residue signal peptides and mature proteins composed of 121 to 123 amino acid residues. Alignment of mature protein sequences revealed high degrees of structural conservation and identity with Group II venom PLA2 proteins from other taxa within the Viperidae. Reverse-phase High Performance Liquid Chromatography (HPLC) profiles of these three snake venoms were obtained separately and chromatographic fractions were assessed for phospholipase activity using an egg yolk suspension assay. The molecular masses of mature proteins were all identified as approximately 14 kDa. Mass spectrometric analyses of the fractionated oligopeptides arising from tryptic digestion of intact venom proteins, was performed for further structural characterization

Arsenic transformation behaviour during thermal decomposition of P. vittata, an arsenic hyperaccumulator

Thermal treatment of P. vittata, an arsenic hyperaccumulator harvested from contaminated land is a promising method of achieving volume reduction, energy production and arsenic (As) recovery simultaneously. In this paper, the arsenic transformation characteristics of field-harvested P. vittata were investigated during its pyrolysis and gasification process. The produced solid residue and flue gas were analysed by a high performance liquid chromatography coupled with inductively coupled plasma mass spectrometry (HPLC-ICP-MS) to determine both the arsenic concentration and speciation. Moreover, the occurrence of arsenic in the solid residues was further identified as soluble and insoluble, which can feed information to the next arsenic recovery step. Results show that the fuel arsenic into gas phase increases firstly from 400 °C to 600 °C, but then drops from 600 °C to 800 °C, probably due to the self-retention of arsenic by CaO enriched in this P. vittata. Further increasing temperature to 900 °C will result in fast arsenic release. Gasification results in slightly higher arsenic release into the gas phase compared with pyrolysi

Experimental and kinetic study of thermal decomposition behaviour of phytoremediation derived Pteris vittata

Combustion and gasification for biomass to energy conversion is often suggested for the management of residual Pteris vittata from phytoremediation. In this study, the thermal behaviour of P. vittata was studied on a thermogravimetric analyser, and the kinetic triplet of biomass sample was further determined for different stages of the thermochemical processes using the Ozawa and KAS methods, subsequently modified by an iterative procedure. Results show that thermal decomposition under combustion condition was complete at a lower temperature of ~500 °C compared to ~700 °C for gasification, indicating the both easily complete conversion of P. vittata by combustion and gasification. Kinetic study shows that although activation energy for each stage under combustion condition is mostly larger than that under gasification, the reaction rate of thermal decomposition of P. vittata under combustion condition is still great larger than that under gasification condition. These findings strongly suggest that thermochemical processes offer suitable methods for the volume reduction and energy production of P. vittata