Alterations in Antioxidant Defense System in the Plasma of Female Khat Chewers of Thamar City, Yemen

Abstract * Corresponding author. e-mail: [email protected]. * Abbreviations used: BChE, Butyrylcholinesterase; GSH, Reduced glutathione; T-SH, Total thiols; OPs, Organophosphate compounds; CAT, Catalase Chewing Khat leaves (Catha edulis) is highly prevalent in Yemen and East African countries. Unfortunately, farmers use to apply pesticide for the better product of Khat. The present study has been designed to investigate the activity of plasma butyrylcholinesterase (BChE) and to assess the antioxidant defense system in the plasma of female Khat chewers in Thamar city, Yemen. Plasma of twenty female Khat chewers and twenty controls (non Khat chewers) were prepared and the activities of BChE and catalase (CAT) were estimated along with the measuring levels of reduced glutathione, total thiols and cholesterol. At biochemical level a significant decrease in the activities of BChE and CAT were observed in the plasma of female Khat chewers (P < 0.05) concomitant with reductions in the levels of reduced glutathione and total thiols (P < 0.05) as compared to non Khat chewers. This alterations on the antioxidants resulted in decrease of plasma cholesterol in Khat chewers group (P < 0.05). The present data show that the production of oxidants which are responsible for reduction in antioxidant defense system might be due to chewing Khat plant with more attention to the pesticide applied to the plant

Pairwise selection assembly for sequence-independent construction of long-length DNA

The engineering of biological components has been facilitated by de novo synthesis of gene-length DNA. Biological engineering at the level of pathways and genomes, however, requires a scalable and cost-effective assembly of DNA molecules that are longer than ∼10 kb, and this remains a challenge. Here we present the development of pairwise selection assembly (PSA), a process that involves hierarchical construction of long-length DNA through the use of a standard set of components and operations. In PSA, activation tags at the termini of assembly sub-fragments are reused throughout the assembly process to activate vector-encoded selectable markers. Marker activation enables stringent selection for a correctly assembled product in vivo, often obviating the need for clonal isolation. Importantly, construction via PSA is sequence-independent, and does not require primary sequence modification (e.g. the addition or removal of restriction sites). The utility of PSA is demonstrated in the construction of a completely synthetic 91-kb chromosome arm from Saccharomyces cerevisiae