A label-free aptasensor for highly sensitive detection of homocysteine based on gold nanoparticles.

In the present study, an original electrode fabrication approach was devised to create a label free sensitive electrochemical aptasensor for the detection of Homocysteine (Hcy) (Homocysteine signal was used for detection). To bind certain targets, synthetic oligonucleotides used as aptamers (APs) were specifically selected. Aptamers are substitutes for antibodies for analytical devices because of their sensitivity and high affinity. In this study, Hcy-Binding-Aptamer (HBA) was grafted onto the surface of Au nanoparticles/Glassy Carbon Electrode (Au/GCE) in order to create an aptasensor. The effects of buffer concentration, buffer type, interaction time, and aptamer concentration were investigated and optimized. In addition, Differential Pulse Voltammetry (DPV) was implemented to identify homocysteine. Favorable performance was achieved at a detection limit of 0.01 µM (S/N = 3) and linear range 0.05-20.0 µM. Furthermore, the fabricated aptasensor displayed desirable stability and reproducibility. The developed electrochemical aptasensor was found to have reasonable selectivity for the detection of homocysteine in the presence of cysteine and methionine. Analysis of real samples showed good ability of the proposed homocysteine biosensor to provide sensitive, quick, easy, and cost effective measurement of homocysteine in human blood serum and urine samples.

Genomic and protein structure analysis of the luciferase from the Iranian bioluminescent beetle, Luciola sp.

To date, two Iranian luciferase genes from the Lampyris turkestanicus and Lampyroidea maculata have been carefully studied. Here, we report the cloning and characterization of the gene and protein of luciferase enzyme from the beetle of an Iranian lampyrid species, Luciola sp. (Coleoptera-Lampyridae). In this study, a Luciola sp. firefly was collected from the Yasouj area of Iran and its luciferase gene sequence was cloned and characterized. The genomic DNA length for this luciferase was the 1950 bp that combined of seven exons and separated by six introns. The results of multiple sequence alignment show that this gene has the most similarity with DNA gene luciferase from the Hotaria unmunsana species. Further analysis determined accurately the location of these introns in the luciferase gene. However, the deduced amino acid sequences of the luciferase gene (548 residues) showed that this luciferase had 97.8% resemblance to luciferase from Lampyroidea maculata species. By in silico modeling of firefly luciferase in an I-TASSER server, the 3D structure of this enzyme was evaluated. The results of phylogenetic tree analysis display the close evolutionary relationship of this luciferase gene and luciferase gene from the Lampyroidea maculata and Hotaria unmunsana.

NGF and BDNF expression drop off in neurally differentiated bone marrow stromal stem cells.

Bone marrow stromal stem cells (BMSC) express two neurotrophins nerve growth factor (NGF) and brain derived growth factor (BDNF) constitutively and can be differentiated into neuronal-like cells and used to treat neural injuries and diseases. The neurotrophins are required for repair of neural tissues. However, it is not evident whether these cells supply the sufficient amounts of the functional growth factors following neuronal differentiation. This study investigates the expression of NGF, BDNF and their processing enzymes Prohormone convertases (PC) Furin, PC5 and PC6 by Real-time RT-PCR during neural differentiation of rat BMSC. The results showed that all inspected processing enzymes are expressed in the cells. The expression of NGF, BDNF and PC5 decreases following differentiation. In addition, BMSCs express Survivin, an anti-apoptotic gene; however, the differentiated cells reduce its expression similar to two neurotrophins, which could make them susceptible to apoptotic death.