Iranian Journal of Biotechnology
Year:2008 | Volume:6 | Issue:3|Papers Count:7

The oxidation of ferrous iron (Fe2+) in solution using Acidithiobacillus ferrooxidans has industrial applications exclusively in the regeneration of ferric iron (Fe3+) as an oxidizing agent for the removal of hydrogen sulfide from waste gases, desulfurization of coal, leaching of non-ferrous metallic sulfides and treatment of acid mine drainage. The aim of this investigation was to increase the bio-oxidation rate of ferrous sulfate by using immobilized cells. Rate of Fe2+ oxidation was determined in a packed-bed bioreactor configuration with monolithic particles being used as support material. Biooxidation of ferrous iron by immobilized cells was investigated in repeated batch culture and continuous operation using a laboratory scale packed-bed bioreactor. On this account, effects of process variables such as dilution rate and initial concentrations of Fe2+ on oxidation of ferrous sulfate were consequently investigated. During repeated batch culture, the immobilized-cells were stable and showed high constant iron-oxidizing activities. A maximum Fe2+ oxidation rate of 6.7 g/l/h was achieved at the dilution rate of 2 h-1, while no obvious precipitate was detected in the bioreactor.

A study was carried out on totally chlorine-free (TCF) bleach ability of dim ethyl form amide (DMF) treated bagasse pulps exposed to CZ-3 and FP 90031-sp strains of white-rot fungus Ceriporiopsis subvermispora. This process involved a bleaching sequence consisting of oxygen and peroxide treatment stages. The effect of enzymatic stage on bleach ability properties was studied and compared with control pulps, processed without enzyme addition. A final brightness of 79-80% International Standard Organization of brightness (ISO) was achieved after complete bleaching. The effects of direct bleaching caused pulp brightening (1.7-1.3% ISO) and delignification (>10%) immediately after the enzymatic stage. Under a peroxide charge of 3% to 9%, the improvements in brightness and the bleach ability of these pulps were found to be superior to those of the control during all peroxide stages. The selective bleaching of each process was assessed by changes of intrinsic viscosity. Generally higher bleach ability and bleaching selectivity of xylanase-treated pulps and the inevitable maximal gain in pulp brightness (or bleach boosting, as a main objective of xylanase application) were only achieved after the first and second peroxide bleaching stages. These substantially diminished by the end of the sequence.

A single nucleotide polymorphism (SNP) in CD24 has been associated with multiple sclerosis (MS) in a population based study. This SNP results in the replacement of alanine (CD24A) by valine (CD24V) at amino acid 57 in the resulting polypeptide chain. In the current study, the genotyping of this SNP and its contribution to MS in 217 patients and 200 healthy individuals of an Iranian population was investigated. The correlation of the SNP alleles with the progression of the disease was determined using the expanded disability status scale (EDSS) and progression index (PI). The data revealed that individuals with the CD24V/V genotype showed a 2-fold increase in the relative risk of MS compared to patients with the CD24A/V (0.27) and CD24A/A (0.25) genotypes (P=0.0193, Odds Ratio 2.4882, 95% CI: 1.416-4.3722). Moreover, the progression of the disease in patients with CD24V/V was much faster than other patients that were examined by ANOVA and the least significant difference (LSD) test. However, in the CD24V/V patients LSD analysis was statistically significant (p<0.05 and p<0.01). These results support the hypothesis that CD24 may function as a genetic modifier for susceptibility and progression of MS through the CD24V/V genotype.

Increased fetal hemoglobin (HbF) in b-globin gene disorders ameliorates the clinical symptoms of the underlying disease. 5-azacytidine, butyrate and hydroxyurea, have been shown to activate g -globin gene expression. It has also been found that hematopoietic growth factors can influence expression of g-globin in erythroid cultures and in animal models. This study was designed to evaluate the in vitro effects of the stem cell factor (SCF) and transforming growth factor-b (TGF-b) on g-globin gene reactivation of erythroid precursors derived from CD133+ cells in vitro. Reverse Transcription-Polymerase Chain Reaction (RT-PCR) analysis showed increased expression of the  g-globin transcript in cell culture groups containing either TGF- b or SCF or both as compared to control (2.2-, 2.7- and 5.5-fold, respectively) (p<0.01). Production of HbF in a differentiated population was demonstrated using flow cytometry. The results of this study suggest that SCF and TGF-b warrant further evaluation as potential therapeutic drugs for the treatment of b-globin gene disorders.

Cotton (Gossypium hirsutum L.) is an important fiber crop in Iran, cultivated on 150000-200000 ha of land. In Iran the estimated loss due to the insect pest is more than 30%. Traditionally, pests are controlled by 10-12 times spraying per growing season of environmentally harmful chemical insecticides (e.g. endosulfan and/or methosystox). In order to produce transgenic cotton resistance to insects, hypocotyl explants were transformed with Agro bacterium tumefaciens strain LBA4404 harboring the recombinant binary vector pBI121 containing the cry1Ab gene under the control of CaMV 35S promoter. Neomycin phosphotransferase (nptll) gene was used as a selectable marker. Inoculated tissue sections were placed onto co-cultivation medium. Transformed calli were selected on MS medium containing 50 mg/l of kanamycin and 200 mg/l of cefotaxime. Plantlets were subsequently regenerated from putative transgenic calli. Polymerase chain reaction (PCR) and southern blot analysis were used to confirm the integration of cry1Ab and nptII transgenes into the plant genome. Western immunoblot analysis of proteins extracted from leaves of transgenic plants revealed the presence of an immunoreactive band with a molecular weight (MW) of approximately 67kDa in transgenic cotton lines using the anti-Cry1Ab polyclonal anti-serum. Homozygous T2 plants (Line 61) for the cry1Ab gene showed significantly higher levels of insect resistance against Heliothis armigera larvae compared with the control plants. Transgenic plants are currently grown in the greenhouse and will be crossed with Iranian cotton breeding lines.

Epitope tagging is a method of expressing proteins whereby an epitope for a specific monoclonal antibody is fused to a target protein using recombinant DNA techniques. The aim of this study was to sub-clone the peroxisomal protein (PEP) cDNA into a mammalian expression vector leading to the formation of a chimeric PEP-cDNA containing the FLAG epitope. The FLAG-PEP recombinant cDNA was constructed using the method of splicing by overlap extension polymerase chain reaction (SOE PCR) and inserted into the pUcD2SRaMCSHyg eukaryotic expression vector. To investigate the intracellular localization of the PEP protein that was linked to the FLAG tandem, the constructed plasmid was used for transient transfection of the Chinese hamster Ovary (CHO) cells. The CHO cells that were transfected with the recombinant plasmid showed peroxisomal localization of FLAG-PEP as was previously shown for catalase.

1, 4, 5, 6-Tetrahydro-2-methyl-4-pyrimidine carboxylic acid (ectoine) is an excellent osmoprotectant. Ectoine and hydroxyl ectoines are of great significance to the biotechnology industry, thus the detection and isolation of ectoine producing bacteria is of great importance. Hence, this study involved the detection of the ectC gene (encoding ectoin synthase enzyme) using polymerase chain reaction (PCR) method. For isolation of moderately halophilic bacteria, environmental samples were collected from various sites of a tannery factory in Isfahan, and the Persian Gulf. A synthetic broth medium was used and the optimum concentration of salt (NaCl) was determined by the microtitre plate method. Based on the alignment of relevant ectC gene sequences available in the GenBank which included sequences from 24 validly described Halomonas species, putative genus-specific primers were designed. Primers were designed in such a way to amplify a 277bp region of the ectC gene in the putative Halomonas strains. PCR analysis showed that 75% (34/45) of the samples belong to the Halomonas genus capable of producing ectoine synthase. Ectoine primer pair was designed to amplify all Halomonas species capable of producing ectoine synthase.