Avicenna Journal of Medical Biotechnology
Year:2014 | Volume:6 | Issue:3|Papers Count:9

The extraordinary revolution in biotechnology has created new possibilities for curing disease and manipulating our genetic heritage. It is easy to see how biotechnology can be used for medicinal purposes. Knowledge of the genetic makeup of our species, the genetic basis of heritable diseases, and the invention of technology to manipulate and fix mutant genes provides methods to treat the disease 1. But it has also created numerous ethical problems that need close philosophical attention. In another words, since biotechnology involves modifying living things for human purposes, there is great potential for ethical concerns. The recent advances in biotechnology present both benefits and risks. They have revolutionized the process of drug manufacture, diagnosis and treatment and the production of animal models for human diseases. There is a tremendous potential for creating new drugs and treatment. This technology raises important ethical issues in the social structures including families, preventive medicine, employment, health insurance etc. We must interact with the general public, to educate them, and prepare them better for the impact of biotechnology. The scientific and medical communities and the public, in general, have to use these powerful tools responsibly, for the maximum benefit of mankind.

Background: Genome instability is a main cause of chromosomal alterations in both somatic and germ cells when exposed to environmental, physical and chemical genotoxicants. Germ cells especially spermatozoa are more vulnerable to suffering from DNA damaging agents during spermatogenesis and also more potent in transmitting genome instability to next generation.Methods: To investigate the effects of g-rays on inducing abnormalities manifested as numerical Chromosome Aberrations (CA) and Micronucleus (MN) in preimplantation embryos, adult male NMRI mice were irradiated with 4 Gy of g-rays. They were then mated at weekly intervals with superovulated, non-irradiated female mice in 6 successive weeks. About 68 hr post coitous, four to eight cell embryos were retrieved and fixed on slides using standard methods in order to screen for CA and MN.Results: In embryos generated from irradiated mice, the frequency of aneuploidy and MN increased dramatically at all post-irradiation sampling times as compared to the control (p<0.01). The frequency of embryos expressed MN was much higher than chromosomally abnormal embryos, although the trend of MN formation was similar to chromosomal abnormalities seen in corresponding sampling times.Conclusion: Irradiation of sperms at any stages of spermatogenesis may lead to stable chromosomal abnormalities affecting pairing and disjunction of chromosomes in successive preimplantation embryos that are expressed as MN. Although chromosome analysis of embryos showed various types of chromosomal abnormalities, MN assay provide a simpler and faster technique for investigating the genotoxicity of agents affecting embryos at preimplantation stages.

Background: Testis tissue xenografting and the resultant sperm in a xenograft may provide a unique approach to rescue the genetic material of males that die prematurely and is a model for the study of human spermatogenesis and can represent an alternative approach for fertility preservation in cancer pa-tients. This study was aimed to evaluate the xenogenic dog sperm in for-mation of male pronucleus following injection into the sheep oocytes.Methods: The in vitro matured slaughterhouse derived sheep oocytes were subjected to Intracytoplasmic Sperm Injection (ICSI) with epididymal, testicu-lar, and xenogenic dog sperm. The ICSI was performed after scoring of the sperm midpiece using an IX71-Olympus inverted microscope with Nomarsky optics. Within 1 hr after injection, the injected oocytes in activated group were exposed to 5mM ionomycin for 5 min. The data were analyzed by Chi-square and ANOVA using SigmaStat, version 3.5, and p<0.05 was considered signifi-cant.Results: The formation of female pronucleus after ICSI of xenogenic sperm was higher than epididymal and testicular sperm in non-activated oocytes. The corresponding rate in activated oocytes was higher or comparable with tes-ticular and epididymal sperm. The rate of male pronucleus formation after ICSI of xenogenic sperm was comparable with injection of two other sperm sources. Oocyte activation had an inductive role in female and male pronu-clear formation.Conclusion: Dog xenogenic sperm was capable to induce oocyte activation and proportion of male pronucleous formation was comparable to the testic-ular and epididymal sperm.

Background: Transient Gene Expression (TGE) gained popularity over the last decade as a rapid method for the production of milligram to gram quantities of recombinant proteins for preclinical studies in biophama industry. Thereby, the optimization of the TGE technique for Chinese hamster ovary (CHO) as the dominant host for the production of biotherapeutics is of great interest to reach the values for Human Embryo Kidney-293 (HEK-293) cells in terms of transfection efficiencies and production titers. TGE efficiencies are cell line and vector dependant.Methods: In transfection efficiency optimization experiments, different starting cell densities, different amounts of plasmid DNA and PEI transfection reagent were investigated to achieve the best conditions leading to maximum transfection efficiencies. Furthermore, in order to investigate the effect of peptone feeding on transfection efficiency, three different sources of peptones with the greatest effect in the CD DG44 basal media were selected; Casein Tryptone N1, Soy petone A2SC and Soy peptone E110.Results: The transfection strategy performed here was able to make an outstanding increase in transfection efficiency of CHO DG44 cell line transfected with pTracer-SV40-mutated t-PA plasmid from 3.6% in our starting nonoptimized condition to 66.93% in finally optimized situation. Moreover, peptone feeding strategy used here was successful to increase volumetric productivities up to 37%. In addition, the amounts of both PEI and plasmid DNA were reduced up to 66% and 25%, respectively compared to our previous protocol.Conclusion: Here we described an optimization process for TGE in suspensionadapted CHO cells based on Polyethylenimine (PEI)/DNA concentration, DNA: PEI ratio, starting cell densities and peptone feeding strategy.

Background: Limited resources for adult stem cells necessitate there in vitro culture prior to clinical use. Investigating mitochondrial DNA (mtDNA) and telomere shortening has proved to be important indications of stem cell validity. This study was designed to investigate these indicators in multiple passages of three adult stem cell lines which were produced in our stem cell laboratory.Methods: In this study, Dental Pulp Stem Cells (DPSCs), Periapical Follicle Stem Cells (PAFSCs) and Human Foreskin Fibroblast (HFF) cell lines were expanded for 20 passages. After 1, 5, 10, 15 and 20 passages, expanded cells were harvested and DNA was extracted for further studies. Common mtDNA mutation was detected by multiplex PCR and telomere shortening was tested by Southern blot analysis.Results: The common deletion was not detected in any of the stem cells or cell lines after several passages. In addition, Southern blot analysis indicated that the mean difference of telomere length between first and last passage was 0.25 kb in DPSC, 0.1 kb in PAFSC and 0.32 kb in HFF which indicates that the mean telomere length in various passages of the samples showed insignificant changes.Conclusion: Absence of mtDNA mutations in adult stem cell lines indicates good mitochondrial function even after 20 passages. In addition, absence of telomere shortening indicates stem cells validity after multiple passages. It is hoped this information could pave the way for using in vitro expansion of adult stem cells for future clinical applications.

Background: L-glutamic acid is one of the major amino acids that is present in a wide variety of foods. It is mainly used as a food additive and flavor enhancer in the form of sodium salt. Corynebacterium glutamicum (C. glutamicum) is one of the major organisms widely used for glutamic acid production. Methods: The study was dealing with immobilization of C. glutamicum and mixed culture of C. glutamicum and Pseudomonas reptilivora (P. reptilivora) for L-glutamic acid production using submerged fermentation. 2, 3 and 5% sodium alginate concentrations were used for production and reusability of Immobilized cells for 5 more trials.Results: The results revealed that 2% sodium alginate concentration produced the highest yield (13.026±0.247 g/l by C. glutamicum and 16.026±0.475 g/l by mixed immobilized culture). Moreover, reusability of immobilized cells was evaluated in 2% concentration with 5 more trials. However, when the number of cycles increased, the production of L-glutamic acid decreased. Conclusion: Production of glutamic acid using optimized medium minimizes the time needed for designing the medium composition. It also minimizes external contamination. Glutamic acid production gradually decreased due to multiple uses of beads and consequently it reduces the shelf life.

Background: Our preliminary data on the protein expression of SORT1 in ovarian carcinoma tissues showed that sortilin was overexpressed in ovarian carcinoma patients and cell lines, while non-malignant ovaries expressed comparably lower amount of this protein. In spite of diverse ligands and also different putative functions of sortilin (NTR3), the function of overexpressed sortilin in ovarian carcinoma cells is an intriguing subject of inquiry. The aim of this study was, therefore, to investigate the functional role of sortilin in survival of ovarian carcinoma cell line.Methods: Expression of sortilin was knocked down using RNAi technology in the ovarian carcinoma cell line, Caov-4. Silencing of SORT1 expression was assessed using real-time qPCR and Western blot analyses. Apoptosis induction was evaluated using flow cytometry by considering annexin-V FITC binding. [3H]-thymidine incorporation assay was also used to evaluate cell proliferation capacity.Results: Real-time qPCR and Western blot analyses showed that expression of sortilin was reduced by nearly 70-80% in the siRNA transfected cells. Knocking down of sortilin expression resulted in increased apoptosis (27.5±0.48%) in siRNA-treated ovarian carcinoma cell line. Sortilin silencing led to significant inhibition of proliferation (40.1%) in siRNA-transfected Caov-4 cells as compared (p<0.05).Conclusion: As it was suspected from overexpression of sortilin in ovarian tumor cells, a cell survival role for sortilin can be deduced from these results. In conclusion, the potency of apoptosis induction via silencing of sortilin expression in tumor cells may introduce sortilin as a potential candidate for developing a novel targeted therapy in patients with ovarian carcinoma to mock control-transfected counterpart.

Background: Re-emergence of pertussis has been reported in Iran despite a high rate of vaccination coverage. Low efficacy of the vaccine might be due to the genetic divergence between clinical versus vaccine strains. In the current study, the genetic profiles of clinical isolates and vaccine strains of Bordetella pertussis (B. pertussis) were assessed by using Pulsed Field Gel Electrophoresis (PFGE).Methods: Following phenotypic and molecular identification of isolates, XbaIdigested genomic DNA of 5 clinical isolates, 2 vaccine strains and a Tohama I strain were analyzed by PFGE along with B. parapertussis as a control.Results: Seven distinct PFGE profiles were found among all examined isolates/ strains. In 5 clinical isolates, 4 profiles were identified whereas the vaccine strains displayed 2 distinct profiles. The reference strain, Tohama I had a distinct profile. Vaccine and clinical profiles had low similarity, with relatedness of approximately 40%.Conclusion: The genetic profiles of B. pertussis were different between circulating isolates and vaccine strains used in the national vaccination programs. Since new genetic profiles of B. pertussis can be disseminated periodically, the profiles of isolates circulating in the population should be monitored over the course of the re-emergence.

Background: One of the most important producers of high quality industrial enzymes is the Gram-positive bacterium, Bacillus subtilis (B. Subtilis). One major limitation that hinders the wide application of B. subtilis is the secretion of high levels of extracellular proteases which degrade the secreted foreign proteins. In this study, homologus recombination technique was used to knock out its protease gene, aprE.Methods: The internal segment of the pro-sequence of aprE gene of B. subtilis 168 with a length of 80 bps and its complementary sequence were synthesized and ligated into pUB110 at EcoR1 and XbaI restriction sites. Competent cells of B. subtilis 168 were prepared and transformed by electroporation using Bio Rad gene pulser as explained in the methods section. Transformants carrying the recombinant plasmid were selected for resistance to neomycin. The success of homologous recombination was checked by PCR amplification of the neomycin gene which was part of the vector and did not exist in the genome of B. subtilis 168. The protease activity was measured using the Protease Fluorescent Detection Kit based on the proteolytic hydrolysis of fluorescein isothiocyanate (FITC)–labeled casein-substrate.Results: The results demonstrated that aprE gene would not be able to produce further active subtilisin E. The reduction of protease activity also confirmed the efficacy of the induced mutation in this gene.Conclusion: It will therefore be a major challenge for future research to identify and modulate quality control systems of B. subtilis which limit the production of high quality protease- sensitive products such as lipase.