IRANIAN JOURNAL OF BIOLOGY
Year:2002 | Volume:11 | Issue:3-4|Papers Count:8

Sulfur-containing compounds in fossil fuels are the source of environmental problem following the combustion of the petroleum and refining process. The conventional desulferization (hydrodesulfurization) of sukfur compounds are not sufficient and suitable to achieve adequate desulfurization. So, microbial removal of sulfur which has significant environmental benefits is recommended. A number of microorganisms have been shown to be able to metabolize sulfur compounds. Due to the low level desulfurization rate in native bacteria, designing recombinant strains to enhance biodesulfurization is interested. To achieve this goal, the first step is to study the molecular basis of biodedulfurization and genes involved in this process in native bacteria. We studied some strains isolated from different part of Iran (isolated by Biotechnological division of industrial and Science Research Organization and Research center of Biochemical Engineering, university of Sharif) for the desulfurization operon. The dsz (sox) biodesulfurization cluster from the prototype Rhodococcus sp. Strain IGTS8 were used as a control in southern hybridization and PCR experiments. Strains were also tested for utilization of DBT (Dibanzothiophen) which one of them was able to use it as sole source of sulfur. This strain contained desulfurization operon (sox) in its chromosome as shown by DNA hybridization (southern hybridization) and PCR techniques. The sox operon in this strain shows some differences with prototype Rodococcus Strain IGTS8. Further experiments for cloning, manipulation and expression of sox operon in Iranian strain are in progress.

The Agropyron- Elymus complex is well known in its economic importance and taxonomic complexities. The aim of present study is to assess the taxonomy of the complex in Iran with regard to phonetic method. Analysis of the data matrix (22 OTUs×33 characters) was done using principle component (PCA) and clustering methods. The resulting phenogram showed two main groups corresponding to the genera Agropyron and Elymus, and 4 main clusters in the largest group corresponding to 5 sections; Caespitosae, Esytrigia, Goulardia, Anthosachne and Clinelymiopsis, of the genus Elymus. A classification and Key for the species was presented on the basis of morphological data. The results aloe showed the usefulness of applying STATISTICA software in plant taxonomy.    

48 specimens of the genus Lolium were scored for 9 vegetative and 13 inflorescent characters. The aim was investigation on the species of the genus in Iran. Raw data were analysed by Factor analysis and cluster analysis. The results by cluster analysis showed that the specimens were divided in to two groups: outbreedings and inbreeding. L. rigidum and L. loliaceum as well as L. persicum and temulentum had close relationships. All the specimens of L. persicum, L. loliaceum, L. temulentum, L. rigidum, L.multiflorum and L. perenne were separated from each others. Length of lemma awn, turgidity of lemma and glume length had the most loadings among the characters.    

Two strains of unicellular green alga, D. salina (Australian and Iranian) were exposed to three different concentrations (0.005, 0.05 and 0.5 mg. L-1) of copper for 36 days of test duration. Results showed that in 0.005 and 0.5 mg. L -1 of Cu +,2 in comparison with control (0.05 mg. L-1) the growth rate and chlorophyll content of the cells were decreased and beta-caroten content was increased. In comparion with control, calcium and magnesium content of the cells, were decreased. EC50 for both strains was 0.5 mg. L -1 –after 96h. In all cases also, Cu+2 did not affect the cell morphology.  

Medicago is known as a relatively salt tolerant plant. The level of salt tolerance can be increased by callus culture and selection. Sterile seed were cultured and then their Root, stem and leaf segments cultured for callus production in MS medium with 2,4-D,NAA, Kin and Yeast extract. After one month callus production from the best explants occurred on the best medium. The experiment carried out in 2 ways. Calli were transferred directly to 120 mM NaCl and in the step method in 30, 60, 90, 120 150 and 180 mM NaCl. After 3 subcultures the final fresh weight of calli were measured. After 3 time subculture in salt free medium selected and unselected were transferred in media with 0, 30, 60, 90, 120, 150 and 180 mM NaCl. After 3 subcultures the final fresh weight as well as the pattern of SDS-PAGE. Results indicated that, the best medium for callus production was MS+2, 4-D (mgL-1). NAA (2mgL-1), Kin (2mgL-1) YE (1grL-1) and the best explants was stem. The rate of tolerance and the growth of the calli in the stepwise selection were better than direct way. Test of salt tolerance stability in the calli showed stable tolerance for salt stress. It can be consider as genetic or epigenetic changes.  

Immature embryos of wheat (Triticum aestivum L. cv. Hyrmand) were cultured on MS medium with different concentration of 2, 4 –D, and embryogenic callus formation were studied. Embryogenic calli were derived from immature embryos grown on MS medium with 1 mg/ L 2, 4 –D.Embroyogenic calli were subcultured in maintenance medium having 2  mg /L 2, 4-D, 100mg/L casein hydrolysate and 500 mg / L glutamine, and with different intervals transferred to liquid medium. These calli were investigated for potential of embryogenesis. Analysis variance of data showed no significant differences in induction of embryogenesis in response to different levels of the hormones. In these media, two main types of calli were formed: embryogenic, off white, compact and nodular callus (type A) and non-embryogenic soft and watery callus. Also a few white and compact embryogenic callus (type B) were formed. Repeated subculture (5-8 month) of the embryogenic callus were rise to a droughty, compact and nodular embryogenic callus (type C), and with more subculture, droughty and friable embryogenic callus (type D) were formed. Embryogenic calli obtained above were cultured in liquid medium in the presence of 2,4-D or ABA, and embryogenesis were studied for 28 days of culturing in presence of 1 mg/ L 2,4 –D. After this period 1.8 mg/L of ABA was added to MS medium. ABA significantly increased embryogenic clumps. Callus clumps were transferred to solid hormone- free medium every two weeks. Various callus types identified, some of them were embryogenic and some were non- embryogenic.  

In field experiments with two Iranian pomegranates (Punica granatum), “Malas-e-Torsh and Posst Sial” cultivars, effects of over- wintering and gibberellic acid (GA3), phosphorous and nitrogen form applications on ion uptake, alkaloid production, flowering and vegetative growth were investigated. In addition, callus growth from petal cultures of pomegranate on MS medium for alkaloid production was studied. Results showed that, when gibberellic acid was applied at 100 ppm, P and K content of leaves decreased, whereas Na content of leaves, dry weight of offshoot, internodes length, flower number and alkaloid content of root bark increased. No effect on fruit number was, observed. Dry weight, and sodium –potassium content of leaves in Poost Siah cv, increased, when they received nitrogen through nitrate form [Ca (No3)2.4 H2O]. Petals cultured on MS medium supplemented with 1mg/1, 2,4-D and 0.1 mg/1, kinetin in comparison with those cultures, which received 2mg/1, 2,4-D and 0.2mg/1, kinetin, produced more callus with lower alkaloid content, Root induction was observed clearly in explants on MS medium supplemented with 1mg/1, NAA and 0.5/1, kinetin.