نشریه زیست فناوری دانشگاه تربیت مدرس
سال هفتم شماره 1 (پیاپی 11، بهار و تابستان 1395)

Many plants of tropical and subtropical areas are severely damaged when exposed to chilling temperatures between 2 and 15°C. Arabidopsis thaliana is chilling tolerant and, therefore provides an alternative model plant system for the identification of chilling tolerance traits. To determine whether the expression of Cu/Zn-superoxide dismutase 2 (CSD2) would increase superoxide-scavenging capacity and thereby improve the survival rate of chilling sensitive (chs) mutants of Arabidopsis, four chs mutant (chs1-1, chs1-2, chs2-1 and chs2-2) and wild-type plants were grown under low (chilling at 13 °C and 4 °C) and normal growth (23 °C) temperatures. The expression of CSD2 was not detected during cold stress treatments, while the wild plants showed the expression of CSD2 under cold stress. The increase of antioxidant enzymes activities (POX and SOD) showed the role of these enzymes in the protection of the chs mutants under chilling treatment, also the increase in polyphenol oxidase activity shows the role of that in the emergence of chlorosis phenotype. The lack of expression of CSD2 gene in chs mutants grown at chilling temperature would support the hypothesis that the expression of these genes was affected due to mutation in CHS genes, when they are chilled.

The amount of waste and agricultural wastes in Iran is very high due to the combination of resources that they have become suitable for ethanol production. Molasses is one of the most abundant and inexpensive carbon sources available and usable for ethanol production. With this application to prevent it from getting into the environment and the product is obtained as a clean and environmental fuel. The main objective of this study was to compare the production of ethanol from molasses by Saccharomyces cerevisiae and Zaymomonas Mobilis. In this study, the fermented juices of grapes are cultivated on the RM culture containing 1% Nystatin at Aerobic conditions and temperature is 30℃. Then the Zymomonas Mobilis was isolated and identified by using staining techniques, biochemical tests, growth in the presence of 7% ethanol and ribotyping. To determine the amount of ethanol production, 10% molasses medium was used. The amount of ethanol at 24, 48, 96, 120, 144 hours in 10% molasses were 1.45, 3.4 and 5.05% for Zymomonas mobili subsp. mobilis IRMH52, Zymomonas mobilis subsp. mobilis ATCC 10988 and Saccharomyces cerevisiae, respectively. In this study, a new strain of Zymomonas mobilis were isolated and compared the production of ethanol with the same conditions showed that this strain of Saccharomyces cerevisiae to produce less ethanol.

Lipases, as an important enzyme group, are able to catalyze hydrolysis or synthesis of esters.The lipase from pseudomonas fluorescens (E.C.3.1.1.3) is a thermophilic kind of lipases (MW around 33 Kd).
In this study, the effect of different concentrations of sorbitol on the activity and conformational stability of Psedomonas fluorescence lipase was evaluated using UV/Vis and Circular Dichroism (CD), respectively. According to the results of thermodynamic studies the 0.6 M concentration of sorbitol was selected for refolding and unfolding kinetic measurements with stopped flow fluorescence apparatus. Kinetics data indicate that unfolding of lipase is performed via two different pathways; one of them is probably involves a synchronous unfolding and dissociation of subunits and the other one comprises a two step unfolding in which the subunits are first dissociated followed by complete unfolding of subunits. We found that more population of protein molecules unfolded with slow phase unfolding pathway when sorbitol is present in the unfolding buffer. Furthermore; refolding kinetics data suggest that in the presence of sorbitol the energy barrier of refolding is reduced.

CO2 biosequestration by using algae is one of the promising and environmentally friend methods. The present study aimed at investigating the ability of Spirulina platensis in terms of growth and carbon dioxide fixation under different salinity levels and also variety of CO2 concentration. To this purpose, analysis of growth parameters including biomass productivity, specific growth rate and carbon fixation rate during the 8-day periods by maintaining the same conditions, under 3 salinity levels (3, 1500 and 34000 µs/cm) and four CO2 concentration (0.03%, 2%, 5% and 10%) were performed. this test have been performed in flat plate reactors by using pure stock of Spirulina platensis culturing in Zarrouk's medium . in all cultures, microalgae showed the highest specific growth rate during the first four days, as 0.35, 0.23, 0.24 and 0.24 d-1 in natural water, respectively. The highest carbon fixation rate and biomass production of Spirulina platensis were related to natural water (the city of birjand) under 10% CO2 concentration( 0.49 and 0.98 gL-1 d-1) that is followd by pure water of 0.45, 0.09 gL-1 d-1 and artificial sea water of 0.42 and 0.84 gL-1 d-1 respectively.the growth rate was lower in artificial sea water because of high salinity.

Silibinin a natural flavonoid has been reported to induce cell death in various types of cancers and also in endothelial cells which shows its anti-angiogenesis effect. However, its molecular mechanism is not clearly defined. In this article, we provided evidence for one of the mechanisms by which Silibinin induces apoptosis in HUVEC. For this purpose, HUVECs were grown on 96 well plates and cell viability was measured by MTT assay and IC50 was determined as 143μM after 24 hr of treatment by Silibinin. Caspase-9 activity in dose dependent (100-300μM) and time dependent (24,48 and 72hr) treatment by Silibinin was assessed using chromogenic substrate LEHD-pNA. Maximum activity of caspase 9 was in 100 μM of silibinin after 48 hours of treatment. DNA fragmentation was analyzed by gel electrophoresis. Cells were incubated with different concentrations of silibinin (100-400μM) and DNA that was extracted from cells which were incubated by 400 μM of silibinin formed a smear on agarose gel. Data obtained from this study showed the ability of Silibinin to inhibit HUVEC cell proliferation through apoptosis induction which indicates the anti-angiogenesis effect of this compound.

Drought is known as an important factor limiting growth and product of field crops in most parts of the world and Iran. In the present work, the genetic diversity of 100 inbred lines of sunflower was investigated based on agro-morphogical characters with simple lattic design with two replications under normal and drought stress conditions. Combined analysis of variance revealed significant differences among lines for most of studied traits. Uneder normal condition, the highest coefficient of genetic variation was observed for stem diameter and the lowest one observed for relative water content. In drought stress condition, the highest coefficient of genetic variation was observed for seed yield per plant and the lowest one observed for days to flowering. The results of correlation analysis showed that there is significant and positive correlation between seed yield per plant with most of the studied traits in both stress conditions. Stepwise regression analysis revealed that under drought stress condition 73.9 percent of seed yield per plant variation was expailed by heed diameter, leaf width and petiol length and in normal condition 73.6 yield grain per plant variation explained by head diameter and plant height. Cluster analysis grouped lines into 4 clusters in each one of normal and drought conditions but the distruption of lines within groups were differents depending to stress environment that present the genetic variability for drought tolerance in sunflower lines.

Multiple sclerosis (MS) is a chronic myelin destructive disease which affects central nerves system. CD4 T cells are a group of adaptive immune system cells that have Pivotal role in immune response against the foreign agents. Th17 (T helper 17) cells are one of the subsets of CD4 T cells which increased in multiple sclerosis patients. MicroRNAs are single stranded non-coding RNAs that regulate protein expression by targeting their mRNA. The aim of this work was to determine miRNAs which probably have effect on theTh17 differentiation pathway by means of bioinformatics methods to suppress this pathway and decrease MS symptoms. by using miRWalk and miRTarBase databases, the probable and validated interactions between some miRNAs and Th17 differentiation pathway proteins were investigated .Disregulated expression of this miRNAs clinically have been shown previously in MS patients. Results showed that miR-9 probably could induce Th17 differentiation from naïve T cells by suppressing negative regulator of Th17 differentiation pathway. In contrast, miR-17and miR-106a/b probably could inhibit Th17 differentiation pathway by suppressing positive regulator of this pathway. Thus, this miRNAs can be considered as potential therapeutic targets for suppression or symptom reduction and also diagnostic markers in MS patients.

Endoglucanase Cel9A from Alicyclobacillus acidocaldarius (AaCel9A), a thermophile enzyme, randomly breaks β1-4 glycosidic bond between glucose units in cellulose polymer and produces oligosaccharides with reducing end. In this study, first of all, E.coli BL21 cells were transformed by pDEST17 carrying AaCel9A enzyme gene for expression of the recombinant enzyme. After expression, the recombinant enzyme was purified by Ni-NTA affinity chromatography column and the purity of the recombinant protein was analyzed by SDS-PAGE. Due to impact of the calcium, pH and temperature on AaCel9A activity, the effects of these parameters were investigated on AaCel9A activity to optimize activity condition by using Response surface methodology. The SDS-PAGE result showed that AaCel9A, with molecular weight of 59 kDa, was expressed and purified. Response surface methodology data reveal that the effect of pH on the activity of the enzyme is higher than temperature and the calcium effect is less than temperature. Results showed that the optimum condition of AaCel9A activity reaches at pH 6.35 and 64.5 ˚C as well as 4.92 mM of calcium. Finally, the high correlation between experimental and predicted date indicated that the proposed model for optimizing the enzyme activity has a high accuracy.