Iranian Journal of Biotechnology
Year:2007 | Volume:5 | Issue:4|Papers Count:10

Currently much debate, attention and concern surrounds the use of genetically modified plants or animals. But there has not been much concern about microorganisms, although we all are aware of the place of microorganisms in the circle of life, their abundance and diversity. There are many examples regarding the application of genetically engineered microorganisms (GEMs), however, like other higher organisms, any modification in the natural properties of microorganisms has to be justified and follow certain rules and regulations. Proposal for the construction of an "Iranian GEMs Bank" is another way of preventing unlimited manipulation on microorganisms: Also establishing the "Iran Microbe Zoo" will help governmental and environmental protection organizations to enhance public knowledge and understanding of the role of microorganisms and the significance of their protection.

In this present study, we examined the differentiation potential of human bone marrow derived mesenchymal stem cells (hBMSCs) into hepatocytes on a threedimentional (3D) nanofibrous scaffold formed by Poly (e-caprolactone) (PCL), collagen and polyethersulfone (PES). The nanofiber was prepared by the electrospining technique. HBMSCs were isolated using combining gradient density centrifugation with plastic adherence. Flow cytometric analysis was used to identify the isolated MSCs. The performance of the cells on the scaffold was evaluated by scanning electron microscopy (SEM) and MTT assay. The hBMSCs were then cultured in a hepatic differentiation medium containing hepatocyte growth factor (HGF), oncostatin M (OSM) and dexamethasone (DEX) for up to 21 days. The results showed that the isolated hBMSCs expressed specific markers such as CD44, CD166, CD105 and CD13. The integrity of the MSCs was further confirmed by their differentiation potential to osteogenic and adipogenic lineages. Scanning electron micrographs and MTT analysis revealed that the cells adhered and proliferated well on the nanofibrous hybrid scaffolds. Immunocytochemical analysis of albumin and α-fetoprotein (AFP) showed the accumulation of these markers in the differentiated cells on the scaffold. Hepatocyte differentiation was further confirmed by showing expression of albumin, AFP and cytokeratin-19 (CK-19) at mRNA levels in differentiated cells. In conclusion, the evidences presented in this study show that the engineered scaffold is promising for maintenance of hepatocyte-like cells suitable for transplantation.

The aim of this study was to investigate the frequency, location and type of rpoB gene mutations in Mycobacterium tuberculosis (MTB) collected from patients in the southern endemic region of Iran. Drug susceptibility testing was determined by using the BACTEC system and the center for diseases control’s (CDC) standard conventional proportional method. In 29 rifampicin-resistant MTB (85%) isolates, 60 mutations and 13 micro-deletions were identified. Missense mutations produced 23 types of amino acid substitutions.In five rifampicin-resistant MTB isolates (15%) no mutations were found in the core region of the rpoB gene. All silent mutations were localized in codon 507. Most frequent mutations detected in Iranian strains, were found in codons 523 and 526. Five alleles in codon 526 and three alleles occurring in triplets in each of the codons 507, 508, 513 were also found. Thus in Iran the highest frequency of common mutations shared between primary and secondary infections was found to occur in codons 523 and 526.

Different control strategies of bed temperature and moisture were investigated using various inlet air temperatures and air fluxes in both the ordinary packed bed bioreactor (without cooling water in the jacket) and the bioreactor with cooling water in jacket. The experiments were carried out within a 1-L solid-state packed bed bioreactor in which Aspergillus niger was cultivated on wheat bran. On-line measurements of oxygen quantity in the outlet air and temperature of the bed and the inlet air flux were carried out in both types of the bioreactors. Effects of certain control strategies on fungal growth rate were compared in both the bioreactors. According to experimental results, using the bioreactor with the cooling water in the jacket is a better strategy for control of bed temperature and moisture during packed bed solid state fermentation. Cumulative oxygen consumption in this bioreactor was approximately 1.7 times higher than other control strategies used in this study.

An isolate from polluted soil identified as Aspergillus sp. MS-100 was able to consume vanadium oxide octaethyl porphyrin as a model for protoporphyrins in crude oil. The isolate degrades about 55% of vanadium oxide octaethyl porphyrin (VOOEP) under optimum conditions during 7 days. The release of more than 0.96 mgl-1 of free vanadium into the aqueous phase was confirmed using atomic absorption. By using the Taguchi experimental design method, the optimum values of pH, temperature and initial concentration of VOOEP were determined as 5.5, 30°C, and 20 mg/l, respectively. The reduction of VOOEP in the culture medium was accelerated by Ag+ and inhibited by Zn2+ and EDTA. The Sn2+ and Pb2+ ions showed a stimulatory effect at 0.1 mM and an inhibitory effect at 1 mM.

Several heavy metal resistant bacterial strains were isolated from sediment and water samples collected from the Persian Gulf and enclosed industrial areas.All the isolated bacteria were identified by 16S rRNA gene sequencing. Isolated bacteria were tested for the presence of plasmids using the modified alkaline lysate method. The method was effective for identification and characterization of plasmids of different sizes without the use of highly toxic chemicals. The study revealed that the frequency of the occurrence of plasmids in heavy metal resistant bacteria was more than that in the common bacteria. The study also demonstrated that about 66% of isolated bacteria carried large (38-62kb) and/or small sized (4- >2 kb) plasmids. The highest plasmid incidence (84.6%) was detected from industrial wastewater bacteria. A slightly higher incidence of plasmids occurred in bacteria isolated from marine sediments (55.5%) compared to that of the marine water (53.8%). The findings suggested that plasmids are highly ubiquitous and predominant in most heavy metal resistant bacteria. Removal of lead and cadmium from solution by some of these bacteria was very efficient, approximately 120 mg/g dry weightas high as 90%. The isolates tested, presented distinct uptake capacities and the best results were obtained for Delftia tsuruhatensis and Pseudomonas AU3411 respectively.

The present study was aimed at the development of a somoclonal variant and isozyme marker for Phyllanthus amarus Schum & Thonn using inter-nodal segments and the enzyme peroxidase. Maximum callus proliferation was obtained on Murashige and Skoog’s medium supplemented (MS) with 1.0 mg/l of 2,4-Dichlorophenoxyacetic acid. Three weeks-old pale yellowish white semi-friable callus was used for organogenesis; the maximum percentage of multiple shoot formation (85%) was achieved after 4 weeks when callus was cultured on Murashige and Skoog’s medium fortified with 1.0 mg/l of 6-Benzylaminopurine.The multiple shootlet formations were also achieved in the presence of the same concentration. The maximum formation of rootlets was observed on MS medium augmented with 1.0 mg/l of Kinetin and 0.5 mg/l of Naphthalene acetic acid. The banding pattern and phytochemical constituent differences were observed between mother plants, directly regenerated via nodal segments, calli, and calli mediated plants. The calli mediated somoclonal variation was confirmed through isozyme (peroxidase) and phytochemical analysis. The isoperoxidase banding profile showed a difference in calli and calli mediated plants. The phytochemical study confirmed the presence of more alkaloids, saponins, tannins and others from calli and calli mediated shoots and roots. Hence the isozyme banding patterns can be used as molecular markers in future plant breedings or genetic improvement programmes.

Infectious bursal disease (IBD) is an economically important viral disease of chickens with worldwide distribution which suppresses the immune system of young chickens. VP2 is the major host-protective protein of infectious bursal disease virus (IBDV). The encoding region of VP2 protein was PCR amplified from a plasmid containing a cDNA fragment of large genomic segment of IBDV, strain D78. This region of 1356 bp was inserted into a eukaryotic expression plasmid, pCDNA4, under the control of human cytomegalovirus (hCMV) immediate early enhancer and promoter. Plasmid DNA was transfected into COS-7 cell line and transient expression of VP2 from the constructed plasmid was characterized by dot blotting with a polyclonal antibody to IBDV.