RESEARCH JOURNAL OF UNIVERSITY OF ISFAHAN "SCIENCE"
Year:2008 | Volume:35 | Issue:6|Papers Count:25

S. clavuligerus is a well known actinomycet for producing a variety of Clavulanic acid beta-lactam antibiotics, especially clavulanic acid. Clavulanic acid, a potent b-lactamase inhibitor, is used synergically in combination with penicillin and cephalosporin to inhibit this b- lactam antibiotic's inactivation. The claR gene, in the clavulanic acid gene cluster, encoding a transcriptional activator, regulates the late steps in the ciavulanic acid pathway. All patents about clavulanic cid production are based on performed researches on claR gene of S. clavuligerus DSM738. Here we have determined claR gene sequence of S. clavuligerus PTCC1705 following its cloning on pMA::hyg vector. The obtained results show the similarity between claR gene sequence of both strains. In future, subsequent S. clavuligerus transformation with these newly created constructs will make different transgenic or genetically manipulated streptomyces to study the effect of claR amount on clavulanic acid production. Also, genetic manipulation of claR using different methods, such as site directed mutagenesis will be done in future using these isolated and confirmed genes.

Self-incompatibility is one of the most important mechanisms by which plants prevent inbreeding. In this investigation, the pollen tube growth of eight cultivars of Petunia hybrida grandiflora was studied in vitro and in vivo in pistils which were self-pollinated and in pistils which were cross-pollinated. In addition, the amount of seed set in inbreeding and out-breeding flowers was investigated as the index of self-incompatibility. Using these results, self-compatible and self-incompatible cultivars were discriminated. After 48 h. of self- and cross pollination, the pollen tube growth was studied by fluorescent microscopy in vivo. The results in all cultivars showed normal growth of pollen tubes on culture medium. Fluorescent microscopy studies showed normal germination and growth of pollen tubes on stigmas. In style, the abnormalities of pollen tube growth were observed in self-pollinated pistils of some cultivars. Some of these abnormalities include pollen tube growth inhibition in 1/3 upper part of the style, variable pollen tube diameter in middle and lower part of the style. Seed set studies showed a significant decrease in seed set of self-pollinated pistils in compared with cross-pollinated pistils. The cultivars contain these abnormalities as well as those with decreasing seed set were defined as self-incompatible in our study. Thus, we could be able to discriminate self-compatible cultivars from self-incompatible ones by these characters.

Antibiotics are used for treatment of honey bee diseasese. Antibiotics lower the numbers of beneficial bacteria in the body. Balance of normal microflora disturbs due to use of antibiotics. Antibiotic use in food animal production has been associated with the emergence of antibiotic-resistant strains of bacteria. In response to these practices and attendant problems, several organizations have called for restrictions on antibiotic use in food animal production. For this reason nutritional additive was used to reduction of antibiotics. Two of these additives are probiotics and citric acid. Both of them are used in honey bee nutrition and have antibacterial activities. Probiotics are defined as live microorganisms, including Lactobacillus species, Bifidobacterium species and yeasts that may beneficially affect the host upon ingestion by improving the balance of the intestinal microflora.The objective of the study was to determine the effect of Saccharomyces cerevisiae as a probiotic organism and citric acid as an intestine acidifying factor that restrict growth of intestinal bacteria on the microflora of honey bee digestive tract In this survey bacteria of honey bee digestive tract were isolated and identified. Then effect of citric acid and probiotics were investigated. Citric acid is effective on bacteria of honey bee digestive tract and its MIC was determined and probiotic Saccharomyces cerevisiae cause to reduce the number of bacteria of honey bee digestive tract.

The present study was undertaken to evaluate subacute toxicity of orally administered fenitrothion (FNT) in rats based on the biochemical and histological examination. The study was conducted on 8-week old male Wistar rats that distributed into four groups (three experimental groups and one control group), were treated orally with different doses (25, 50, 100 mg/kg BW) of fenitrothion for 28 consecutive days. After treatment, blood samples were collected for biochemical studies, also liver and kidney samples were taken for histological studies. Results indicated that exposed groups led to significant dose-dependent increase in serum glucose and cholesterol levels. Serum total protein, albumin and triglycerides were decreased not significantly in exposed groups when compared with control. Results showed that the histopathological changes in the liver were mainly represented by parenchymatous degeneration of hepatocytes with mild necrosis, leucocytic infiltration in the portal area, severe congestion and hemorrhage. Marked tubular dilation, hydropic degenerescence in tubular epithelium, moderate congestion and hemorrhage in the cortical and medulla part of the kidney were recorded. Generally the degrees of observed variations were found to be dose dependent.

Most of the gram negative bacteria, secrete signal molecules called N-acyl homoserine lactone (AHL). These molecules have regulatory effects on many of bacterial genes. This regulatory mechanism which is cell-density dependent is called “Quorum sensing”. Pseudomonas aeruginosa is an opportunistic pathogen that uses quorum sensing to control many of its cellular functions such as production of virulence factors. One of these factors is pyocyanin pigment. This compound has been shown to disrupt the beating of human cilia and inhibit lymphocyte proliferation. Various species of higher plants secrete substances with AHL mimic activity. These compounds can inhibit quorum sensing controlled phenotypes. In this study, we examined the inhibitory effect of exudates of Sorghum bicolor (L.) Moench seedlings on the synthesis of pyocyanin in P.aeruginosa PTCC 1430 and we found that the exudates of seedlings of this plant are able to prevent the synthesis of pyocyanin, but have no inhibitory effect on growth of bacteria.

Glyphosate is a broad spectrum herbicide that hnhibits the 5- enol- pyruvylshikimic acid 3-phosphate synthsae (EPSPS) enzyme Which is key enzyme of shikimate pathway. One of the major approaches taken to obtain glyphosate tolerant plants is to over produce the target enzyme EPSPS. A cDNA clone encoding A. thaliana EPSPS was cloned into the pBI121 binary vector under the control of CaMV 35S promoter to abtain high level expression of the enzyme. The At EPSPS and NPT II transgenes were transformed into cotyledonary explants of rapeseed via A. tumefacience. The green transformed plantlets were obtained on selective medium suplemented with kanamicin. These plants were evaluated by PCR, DNA dot blotting and RT-PCR for confirming transgene integration and expression. T1 plants abtained from seeds of T0 transgenic plants. Phenotypic assay for glyphosate resistance and quantitative analysis of shikimate were performed after spraying the T0, T1 and wild type plants with 0, 2.5 and 5 mM glyphosate. The tesults were indicating the increased glyphosate tolerance in T0 and T1 transgenic plants.

Peroxisomes are single membrane eukaryotic organelles that perform variable functions depending on the tissue, the developmental stage or environmental conditions. Peroxisomal matrix proteins are synthesized in the cytoplasm and targeted to peroxisomes by virtue of a peroxisomal targeting signal (PTS). One of the peroxisomal matrix proteins-Peroxisomal Protein (PEP)-has shown different pattern of expression in mouse embryo in various tissues, but the reason is unclear. PEP-cDNA was sub-cloned in pGEX-6p-2 prokaryotic expression vector in order to label this gene with GST to purify PEP protein for further biochemical analysis and identifying related proteins later. PEP-cDNA was inserted downstream of FLAG gene and then inserted in pUcD2SRMCSHyg eukaryotic expression vector to express tagged-PEP protein for transient transfection analysis and identifying localization of PEP protein. Our results clearly demonstrated that PEP and FLAG-PEP were inserted into the vectors appropriately and they were free from mutation.

Salt stress accounted as a factor which limit plant growth and development. Ultraviolet radiation also has a major morphological and physiological effect on plants. In this research the effect of pre-treatment with UV-C on seed germination, mean time required for seed germination, sugar, praline and ion leakage in shoot and roots in two wheat cultivars, Dez and Darab under salt stress was investigated. The results showed that salt stress reduced seed germination percentage but increased the mean time required for germination. pre-treatment of seeds with UV-C radiation ameliorated the reduction of seed germination couced by salt stress. Also the time required for seed germination was improved. salt stress increased sugar, proline and ion leakage in roots of those plants which were under salt stress. Pre-treatment with UV-C had significant effect on proline content and ion leakage and ameliorated the negative effect of salt stress.

Diabetes is a metabolic disorder characterised by hyperglycemia resulting from perturbation in insulin secretion, insulin action or both. Juglans regia (Juglandaceae) has been used in Iranian ethno - medicine in the treatment of diabetes. In this experience the preventive effect of hydroalcoholic extract of Juglans regia leaves on activity of AST and ALT in alloxan - induced diabetic rats was investigated. 18 male Wistar rats, with body weights of 180–220 g were randomly allocated into three groups with six animals per group: first group, nondiabetic rats; second group, diabetic rats; third group, nondiabetic rats treated with hydroalcoholic extract of Juglans regia leaves (200 mgkg-1B.W.) before and then inducion diabetes. In order to induce diabetes, alloxan was administered as a single dose (120 mgkg-1B.W.), intraperitoneally. At the initial and the end of 2 and 6 weeks of experimental period, rats were fasted for 16h, and then fasting blood samples were collected in heparinated tubes. Sampling was performed from the orbital sinus. The results indicate a significant difference in AST and ALT levels in the diabetic group compared with the other groups (p<0.05). Histological studies of the liver of these animals, demonstrated the same results. These results show that the hydroalcoholic extract of Juglans regia leaves could effect on prevent and improve the symptoms of diabetes. 

For studying different sensitivity of plants to heat stress, understanding of the factors that causes lack of pollination, in fertilization and induce flower and fruit abscission and ultimately induce drop in yield is necessary. In this study the possibility of physiological changes during heat stress which cause yield reduction in Capsicum annuum L.cv. malali. were investigated. The content of reduced sugars and total proteins of flower and leaf in both control and heat stressed plants were measured and the quality of proteins in both leaf and flower were investigated using electrophoritic technique. The pattern of pollen grain growth on stigma and the growth of pollen tubes in style were investigated using florescent technique. The reduced sugars in those flowers formed under heat stress was significantly lower than control but no significant differences between reduced sugars in leaf of heat treated and control was observed. Total proteins of both flower and leaf in heat stressed plants was significantly lower than control. The quality of the proteins in both leaf and flower of stressed plants changed when compared with control based on pattern of protein on gel electrophoresis. One new band of protein with molecular weight of 23.75 KD was observed in both leaf and flower of heat treated plants. The observation of anther showed increase in unviable pollen grains. Those pollen grains which germinated on stigma and penetrated into style were unregulated and decreased significantly in those flowers which were under heat stress. More investigation in physiological responses to heat stress and more importantly those which cause unsuccessful fruit formation under heat stress are necessary for understanding the effect of heat stress on yield till can be used in plant breeding and producing heat tolerant plants.

Medicinal plants are rich in natural antioxidants and employed as traditional medicine to treat many diseases.  Walnut and safflower have been used in Iranian traditional medicine - as therapeutics for treatment of diabetes mellitus. 24 male rats, weighting 180–220 g, were randomly allocated into four groups with six rats per group. First group, nondiabetic rats; second group, diabetic rats; third group, diabetic rats treated with hydroalcoholic extract of safflower petals (200 mgkg-1BW) and fourth group, diabetic rats treated with hydroalcoholic extract of walnut leaves (200 mgkg-1BW). At the beginning of tests and end of 2th and 6th weeks of experimental period, the blood sugar, HbA1c and insulin levels were measured.  SPSS software was used for statistically data analysis. The results indicate significant difference in blood sugar and insulin levels in the other groups compared with the diabetic group (P<0.05). These results show that the hydroalcoholic extract of safflower and walnut are effective in treatment of diabetes. It seems these effects are related to flavonoides and their antioxidant effect. Further biochemical and pharmacological investigations should be carried out to elucide the mechanism of action in detail.

Variance and Covariance components, heritability and genetic correlation of economic traits in hybrids of six lines of Silkworm were estimated. In all hybrids, cocoon weight heritability was superior then cocoon shell weight heritability. Heritability of cocoon shell percentage was lower then other traits. There was a height positive genetic correlation between cocoon weight and cocoon shell weight and there was low genetic correlation between cocoon weight and cocoon shell percentage too. Heterosis effect on means of cocoon weight and cocoon shell weight was positive and increase in heterosis percentage increased means of this traits. With increase in recombination percentage in cocoon shell percentage, mean of this trait increased. The results showed that there was an inverse relationship between Heterosis and recombination effects. Also genetic gain and means of triats in 151, 152 and their hybrids, were upper than others. So it is expected that the use of these liens is better in commercial level.

In the present study, transgenic tobacco plants carrying SFL1 promoter were propagated on MS medium. Then calli were obtained from transgenic and non transgenic plants. The whole plant was regenerated from callus in the regenerated medium and in each step of regeneration, plant samples were analyzed using GUS staining method for presence or absence of SFL1. The SFL1 promoter in metabolically active cells and those elongating was expressed very well. It is possible that this gene has a role in cell division and cell elongation in the plant system.

Jasmonic acid and methyl jasmonate is linolenic acid derived cyclopentanone based compounds which widely distributed in the plant kingdom. In this study the effects of salinity stress and methyl jasmonate on shoot fresh weight, sugar, protein, anthocyanine and lipid proxidation in 3 varieties of Carthamus tinctorius were investigated. Plants were irrigated for two weeks with 0, 6, 12ds/m salinity sodium chloride. Plants were also sprayed with 0, 0.1, 0.5 m mol methyl jasmonate for 1 week. After two weeks plants were harvested. Salinity and MeJA reduced shoot fresh weight, anthocyanine and leaf area but increased leaf sugar and malondealdehyde.

Peroxisome proliferated activated receptor g type 1 contains various functions  in the cells including,  regulation of cell growth and development, regulation of immune responses and energy homeostasis and regulation of stem cell differentiations. The aim of this study was to clone PPARg1 cDNA in a mammalian expression vector in a chimeric cDNA type, encompassing PPARg1 cDNA with EGFP cDNA for further transfection into the stem cells to study the role of PPARg1 in the process of stem cell differentiations. At the first step, total RNA was extracted from fat tissue of an adult mouse. Using specific primers PPARg1 cDNA was amplified to produce the entire length of ORF. RT-PCR products containing PPARg1 cDNA were treated by enzymatic digestion and inserted into the pEGFP-C1 downstream the EGFP cDNA and were used for transformation into bacterial competent cells. The positive colonies which showed inserted PPARg1 cDNA were selected for plasmid preparations and additional analysis performed to ensure that PPARg1 cDNA was inserted properly. Our results from enzymatic digestion and sequencing confirmed as it was expected, PPARg1 cDNA was amplified and cloned correctly. This cDNA gene encompasses 1428 bp.

Several epidemiological and experimental investigations have been carried out recently, in order to evaluate the biological effects of static magnetic fields. Despite these studies, exact molecular mechanism underlying these effects is yet to be understood. In the present study the effect of 15 mT static magnetic field on the activity of antioxidant enzymes and flavonoid content of broad bean (Vicia faba L.) was investigated. The results showed a significant difference between the activity of antioxidant enzymes as well as total content of flavonoids in treated plants. The results suggest that static magnetic field can interfere with antioxidant defence system and produce oxidative stress in plant. This may alter biological functions of cells by increasing reactive oxygen species and free radicals.

Regarding the importance of Amphibian in biological studies, In this article, we studied embryonic stages of Rana macrocnemis psudodamatina from fertilized egg to the end of larval metamorphosis in aquarium conditions. In order to do this task the fertilized eggs were collected from their natural habitat and transferred to an aquarium in the laboratory. Afterwards, every few hours some samples were taken from the aquarium and fixed for morphological characteristics to identify their developmental stage by the aid of a stereomicroscope. In summery, three hours after transferring the embryos were at two-cell stage. Four hours after this the samples were observed as four-cell embryos. Five hours later, the embryos were at the stage of gastrulation and six hours after the beginning of gastrulation the embryos were at the early neurolation. Eight hours after that, neural folds were closed and embryos started to elongate. Nine hours after the beginning of appearance the tail bud, olfactory pits in the region tadpole’s head were distinguishable. On the fourth day, tail erected and started to take a position alongside the body length which continued during the fifth day as well. External gills could be seen on the day of six. Sampling which were performed at 10:30 of the eighth day showed that the External gills have been degenerated. During the period of nine to 16th day, tadpoles were just growing and their body size increased without any discernible morphological changes. At late 16th day two hind limb buds began to appear which completed their development until 22nd day of study. Formation forelimb began on 25th day and completed its growth on 35th day. Simultaneously degeneration of tail became clearer on the 73rd day. Up to this stag the samples appeared as juvenile frogs without any tail. In general, these stages lasted almost 73 days.

Probiotics are living microorganisms, which have health benefits for human and animals. The purpose of this research has been studied probiotic properties of isolated bacteria from corn silage and rice bran. In this study, two species of Lactobacillus have been isolated from corn silage and rice bran Iran's cold region (Broujerd, Tabriz) by anaerobic culture. The biochemical tests were performed as: Gram staining, catalase reaction, growth at 10oc, 50oc, arginine hydrolysis, carbohydrates fermentation. Acid tolerance and their growth against bile salt was measured. For increase of stability, encapsulation of isolated bacteria were performed by alginate and chitosan polymers. The results showed that the isolated bacteria are two species of Lactobacillus. They have ability to fermentate of carbohydrates, only Lactobacillus from silage has ability of growing at 50oc. Further more, these bacteria have ability growth at acidic environment and growth exposure to bile salt at interval times. The encapsulation of bacteria has increased their viability. The results showed that the isolated bacteria could be used as a probiotic for feeding to domestic animals. The isolated Lactobacillus from rice bran could be used as food supplement for domestic animal.