MODERN GENETICS JOURNAL (MGJ)
Year:2007 | Volume:2 | Issue:2|Papers Count:9

Collecting and conserving of plant genetic source is important in the world Collecting of different plant genetic resources, especially in wild relatives of crops is one of the most important duties in gene banks. There are some objectives for collection of genetic resources including long-term conservation and evaluation of genetic diversity. Diversity is the most important factor in the collection of plant genetic resources in order to their long-term conservation and utilization for breeding programs and agricultural development. The most essential collector duty is the identification genetic structure of collecting materials which is the most suitable definition for spices in one site. There are four main factors in the collection program: 1) sampling of about 50 populations in one geographical region, 2) sampling of 50 plants in each population, 3) random sampling in each site, 4) sampling of enough seeds or vegetative materials in each plant. Collection of materials for long-term conservation and evaluation of genetic diversity in the gene banks should be aimed of diverse population and gene pools. Priority in the collection programs favors under erosion species and populations. The collector should have complete knowledge about plant pollination and fertilization systems. The important factors for planning of collection of crop family and their wild relatives are: the most suitable date for collection, and targeted collecting region should have good climatic diversity, the choice of region for as many as different species and populations. The selection of collection site, distance between 2 sites, number of plants and seed per plant in each sample, systematic identification of materials, and recording of identification data are essential in the collection programs. Genetic diversity of landraces in the especial site is essential in collection programs. Therefore, as far as farms are the possibility of genetic diversity in landraces is high.If the climatic conditions in the collection region and sea elevation of the site would be the same, the distance between two farms should be consider about 20-50Km. Collection of landraces may operate in one or two stages. The two stage collection is done when we are looking for unique genotypes. In some cases that seeds are very small, such as clover seeds, the sampling amounts should be larger so that the suitable diversity of samples is acquired. All in all, it is essential with respect to scientific points in the collection programs to acquire higher genetic diversities; genetic erosion should be avoided from, especially in cases that their seeds are low.

In this study a new reporter system based on thermostable lichenase (b -1,3 -1,4 - gluconases) of Clostridium thermocellum was developed to study the gene expression regulation in prokaryotic (E. coli) and eukaryotic (Yeasts and plants) cells. Lichenase is a thermostable enzyme that specially hydrolyzes b-1,4 linkages adjacent to b-1,3 linkages in mixed-linkage b-glucans,but does not attack pure 1,3 or 1,4 linkages. Detection of the thermostable reporter enzyme is simple and sensitive (the in situ zymogram technique and plate test). For evaluation of potential of lichenase as a transcriptional reporter, the expression level of the modified lichenase gene (licBM2), under control of different constitutive and specific promoters, in E.coli (T7 and lacZ), yeasts (Gal, and TDH), and plant (light -inducible promoter for rbcs gene) cells, has analyzed. The results showed that the lichenase has many properties indispensable for a transcriptional reporter system, because for different promoters, different levels of expression of the lichenase were observed. The possibility of application of lichenase as a translational reporter was assayed. The cry3a-licBM2 and cry3aM-licBM2 hybrid genes were constructed, in which the wild type and modified cry3a gene sequences, coding crystal protein effective against Coleoptera, in reading frame were fused with reporter gene. The E.coli, yeasts and potato cells were transformed with these constructions. The comparison expression analysis of the native cry3a, modified cry3aM, hybrid cry3a-licBM2, and cry3aM-licBM2 genes in bacterial and yeast cells showed that modification of the native gene sequence increased expression level of this gene in eukaryotic cells- yeasts. Results of plant transformation, promoter activity assays under light induction using lichenase activity and bioassay showed high (about 100 times more than the wild type gene) and stable expression of hybrid gene in transgenic plants. The presence of lichenase as reporter and selectable marker was shown to facilitate selection and analysis of the recombinant protein expression in transgenic organisms, which is of importance for fundamental and applied studies, since it is simple, precise, inexpensive, and not time-consummg.

Some plants are naturally able to acquire nitrogen from the air through a process called symbiotic nitrogen fixation. In soybean, a close interaction between the root and Bradyrhizobium japonicum results in the formation of nitrogen-fixing nodules. Both partners benefit from this interaction: the bacterium gains sugar from the plant, and the plant gains reduced nitrogen. Regulation of this symbiosis is necessary for optimal plant development. Auto regulation of Nodulation (AON) is the main genetically-controlled mechanism that regulates nodulation. To identify genes that function in either the shoot or root to regulate AON we have utilized transcriptional profiling and quantitative real-time reverse transcriptase (QRT) PCR to analyze gene expression in wild type and the GmNARKAON mutant. QRT-PCR experiments confirmed the expression of two genes (GmaAffx.32318.1 and Gm.5873) that were predicted by Affymetrix microarray analyses to be decreased in wild type related to mutant and regulated in the leaf by GmNARK in a rhizobia-independent manner. One of these genes (GmaAffx.32318.1) that were sequenced is predicted to encode a Ca-transporter, with 80% similarity to a heterologous gene in rice. QRT-PC Ranalyses for another 4 candidate genes didn't show any significant differences between wild type and GmNARK mutant plants, as suggested by the microarray analyses. Microarray and QRTPCR analyses of gene expression in specific root zones of wild type and GmNARK mutant plants suggests that a HMG-CoA reductase I may function in the root to regulate nodule number. This gene was cloned by BAC library Screening and its predicted protein has 85% similarity to HMGRl of Arabidopsis. The discovery of new components in the AON circuit enriches our ability to investigate systemic control of plant development and its integrative in kages to other signaling networks.

One of the strategies adopted for development of glyphosate resistance is to over produce the enzyme 5-enol pyruvylshikimate-3-phosphate synthase (EPSPS) of the shikimate pathway in order to enable crops to survive under herbicide application. EPSPS geneshave been isolated from plant and bacterial sources and expressed in oilseed plant under the control of CaMV 35S promoter in the present study T1 plants were generated and subjected to molecular and phenotypic analyses. Kanamycin and glyphosate resistance in seedling and hypocotyl sections were analyzed. The Mendelian segregation of the trait was also determined and the presence and transcription of EPSPS genes were studied in T1 plants by PCR and RT-PCR, respectively. Furthermore, glyphosate resistance of T1 lines and quantitative analysis of shikimate was performed after spraying the adult plants with herbicide. The results were indicating the increased glyphosate tolerance in transgenic plants.

Effect of triploidy induction on some hematological indices changes in all-female diploid and triploid rainbow trout, Oncorhynchus mykiss, at 20 months of age and prior to maturation was investigated in Shahid Bahonar Hatchery Center of Salmonids in Kelardasht-Iran in winter 2005 (mean temperature of 1.5oC). All female diploids were obtained by insemination of spermatozoa from sex reversed females (Neomale) with oocyte of normal females. All-female triploids were also produced similarly and by using heat shock of 26.5oC for 20 minutes to eggs 20 minutes post fertilization. Blood samples were taken from fish caudal vein using 5% EDTA as anticoagulant. Hematological data indicated that mean number of total erythrocytes, hematocrite value and hemoglobin content were significantly lower (p<0.01) and mean corpuscular volume, mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration were significantly higher (p<0.05) in all female triploids. Furthermore, the results showed that mean number of total leukocytes was significantly lower in triploids than in diploids (p<0.01), but there was no significant difference in differential counts between Lymphocyte and Neutrophile percentage in diploids and triploids (p>0.05). Also, biometric results of 32 diploids and 28 triploids showed that mean weight of all-female diploids (348.90gr) was significantly (p<0.01) higher than that of all-female triploids (307.77gr), but there was no significant difference in total length fork length, standard length and body depth indices between these two groups (p>0.05). Final results revealed that although erythrocyte hematological indices were lower in triploids, but increased mean corpuscular volume and consequently higher mean hemoglobin concentration have set the equivalency between hematological indices in all-female triploids.

Thrombophillia is defined as tendency to thrombosis. Deepvein thrombosis (DVT) and pulmonary embolism are referred to venous Thromboembolism. Thrombophillia has genetic and acquired causes. Genetic causes include: Antithrombin III and protein C, S deficiency, activated protein C factor resistance (FactorV leiden) and Hyperhomocysteinemia. Acquired causes include: delivery, contraceptive usage, estrogen therapy, surgery and so on.Hyperhomocysteinemia is caused by mutations in genes which, their enzymatic products, are involved in homocysteine metabolism; particularly mutations in nucleotide 677 (C®T) ftom methylenetetrahydrofolate reductase gene. Since this variant exhibits decreased enzymatic activity at 37°C and increased susceptibility to temperature at 46°C, it's known as thermolabile variant, this is concurrent with elevated level of total homocysteine in plasma. Hyperhomocysteinemia causes damage to vessel wall endothelial cells and culminates to thrombosisby diversemechanisms. In this cross-sectional descriptive study 250 throm botic patients were recruited. The mean age of the patients was 38.99±13.54 years. Frequency of the mutation in patients was 30.8%, including 23.2% heterozygote representative and 7.6% homozygote representative. 41.6% of mutant patients were male and 58.4% were female. There was a meaningful relationship between ftequency of the mutation and thrombosis in lower extremity organs (P=0.024). It seems necessary to evaluate idiopathic thrombophilic patients for this mutation.

Occurrence of cross-resistance to structurally and functionally unrelated drugs, called Multidrug Resistance (MDR), is a main cause of failure in the chemotherapeutic treatment of malignant disorders. Several mechanisms of MDR have been identified; one of those mechanisms is the over expression of ATP-dependent membrane proteins that function as drug-efflux pumps. One of the well-known genes responsible for drug resistance is Multidrug resistance-associated protein I (MRPI) gene. The association of MRPI with clinical drug resistance has not systematically investigated in Iranian pediatric leukemia patients. We aimed to use Real-Time RT PCR technology to study the association between MRPI gene and MDR phenotype in Iranian pediatric leukemia patients. The expression level of MRPI was determined by quantitative Real-Time RT PCR using total RNA isolated from peripheral blood of 42 Acute Lymphoblastic Leukemia and 10 healthy individuals. The patients were divided into two groups. Patients who respons to chemotherapy and were in complete remission (CR) and patients at relapse stage. The association between expression level of MRP1 and response to chemotherapy was investigated. We found there is an over expression of MRP1 in most Iranian pediatric leukemia patients at relapse stage.