JOURNAL OF SCIENCE (UNIVERSITY OF TEHRAN) (JSUT)
Year:2006 | Volume:32 | Issue:1 (SECTION: BIOLOGY 1)|Papers Count:21

Rhizobial inoculants play much important role in increasing the efficacy of symbiotic N2 fixation in leguminous plants. This research was conducted toward preparation of Rhizobium inoculant for beans (Phaseolus vulgaris L.) and formulation of carrier using native inorganic and organic substances. In this study efficacy of 15 compounds, including simple basic compounds and their combinations, were evaluated with reference to their capacity for maintaining high concentration of active bacterial population. Physical characteristics including moisture, water-holding capacity, pH, ash and fiber content designated and the combinations were prepared by mixing of these 'compounds. A collection of nitrogen fixing Rhizobia was isolated from roots of native varieties of the mentioned plants and preserved as pure cultures under appropriate condition. Foregin strains were obtained from CIAT. Each of the  compounds was packed in polytene bags and gamma sterilized. Sufficient amounts of bacterial suspension were added to the carrier compounds to prepare the inoculants containing uniformly distributed bacteria. Getting samples from each of the inoculants and determining viable cell count over a 137 d period revealed the performance of inoculants made from coalcontaining mineral soil. Nodulation tests were carried out according to two different procedures: 1) under sterile condition (in vitro) and 2) in non-sterile condition (in vivo). Nitrogen fixing ability was qualified by quantifying of nodule formation and also by measuring of acetylene reduction capacity in nodules. The superior N2 fixing quality was determined in strains 1 and 7001. Results showed that mixed complex compounds generally acts better than simple compounds in maintaining higher levels of active bacterial population and bacteria could survive in concentrations as high as 109 CFU g-1 over a four months period. Two types of carriers including J (a mixture of coal containing mineral soil, peat-like compound and prelate) under sterile condition (in vitro), and A (containing peat like compound) under unsterile condition in vivo) showed the best results and maintained active Rhizobia at high concentrations 109 and 108 CFU g-1, respectively. In comparison, after a 4 month period concentration of bacteria inpeat like carrier was 107 times more than that of weak carriers such as D (bagasse containing carrier).

The present study includes the examination of Binaloud mountain range southwestern slopes north of Neishabour with an area around 500 km2 covering town of Kharv and Baghshangach village and the areas between them from floristical point of view. The altitude of the area ranges from 1300 to 3500m, the mean annual rainfall is 239.9 mm and the mean annual temperature is 14.25oC. The area comprises 487 plant species and subspecies belonging to 299 genera and 67 families. The largest families in the studied area were Asteraceae with 71 species, Poaceae with 50 species, Fabaceae with 45 species and Brassicaceae with 30 species, respectively. Therophytes constituting 37% of the biological types are dominant, followed by hemicryptophytes and chamephytes with 34% and 12%, respectively. From the standpoint of vegetation types, 48% of the chorotypes belong to Irano-Turanian vegetative elements and the rest relate to one, two, three or various other vegetation regions or have a global distribution. Based on the type of vegetation, type of basin and accessibility to water, the habitats can be divided into flat plains, rocky-dry slopes, wet slopes, aquatic habitats, landslides and degraded-land habitats.

Growing plants on soils containing toxic levels of heavy metals results in growth reduction and transfer of heavy metals to food chain. Copper and Mn are among the important metal contaminations of agricultural and pasture soils respectively. The physicochemical properties and thereby the tolerance mechanisms of plants against toxic levels of Cu and Mn are very different. In this research three important crop species including rice, maize and sunflower were used to study the physiological responses of plants to toxic levels of these heavy metals. Results showed that, all tested species were more sensitive to Cu than Mn at equimolar concentrations in the medium. Rice was the most tolerant plant to Cu and the most susceptible to Mn toxicity. In contrast, sunflower was the susceptible to Cu and tolerant to Mn. There was any positive relation between the rate of metal accumulation and growth reduction in all of the studied species, so that, the most tolerant species for Cu and Mn (rice and sunflower, respectively) were also the most accumulating species. Comparison of uptake and translocation of two heavy metals demonstrated that in all three tested plants the uptake values of Cu was higher than that of Mn, and in contrast, the highest translocation values were obtained for Mn comparing to Cu. Therefore, roots were the main accumulating organs for Cu, and shoot the most accumulating parts for Mn. Retranslocation experiment showed that, loaded Cu at toxic levels in the first and second leaves, was remobilized near completely to younger leaves. In contrast, any reduction of Mn content in the old leaves was shown throughout the growth period, in the exception of that in rice. A higher remobilization of Mn in the latter species was likely the cause of a higher susceptibility to Mn toxicity and the cause of a poor apoplasmic compartmentation.

Primary and secondary growths of main and lateral axes of Eucalyptus gunnii clone 634 young trees as well as some other aspects related to stem bending were studied in a small group of vertically left and inclined young trees and followed for a period of fourteen weeks. Although all the young trees, i.e. inclined and straight ones, did produce tension wood in the form of G-fibres, tilting was proved to be greatly effective in G-layer formation. Three different types of G-fibres were distinguished, with thin G-layer without an 53; with moderate to thick G-layer with an 53 and "faint" G-layer. The results of this experiment suggest that encountering the interior and exterior stresses the eucalypt employs at least three mechanisms: differentiating secondary xylem gelatinous fibres, eccentricity of growth compatible to G-fibres production and gelatinous fibres in phloem on the upper side of the leaned axes.

Plant oils are main sources of energy and basic nutrients that supply essential fatty acids, vitamins and antioxidants. We studied qualitative and quantitative changes of lipids of olive leaves and fruits during fruit ripening in Manzanillo and Dezful cv.S grown in Dezful, Khozestan. During ripening of fruits, we measured totallipids and analyzed fatty acids by Gas Chromatography in on and off years. The results showed that; important fatty acids of leaves and fruits were oleic acid, palmitic acid and linoleic acid. Leaves showed an increasing in percent of palmitic acid but a decreasing in percent of oleic acid during fruit ripening, and fruit showed an increasing in percent of oleic acid but a decreasing in percent of palmitic acid during fruit ripening. Total lipid was increased during fruit ripening.

Charlock (Sinapis arvensis) is frequently found growing in colza (Brassica napus) crops and is a serious weed in the fields. There is much evidence that allelochemicals released from certain weeds into the soil. It was observed when colza fields infested with charlock. In present research, samples of colza and charlock were collected from field. Etiolated seedling of colza were cultured in Hoagland's culture with or without shoot and root of charlock (in 5-6 foliar leaf stage) aqueous extraction at 0.5% and 1.5% concentration of stock solution (10 gr dried material extracted in 100 ml DW). Shoot extract reduced shoot and root length, leaf area and fresh weight of colza, but root extract were only at 1.5% significantly affected. Shoot extract at 1.5% reduced chlorophyll a, and total chlorophyll of colza compared to control, but root extract at the same concentrations reduced chlorophyll b. In addition shoot extracts reduced Hill reaction. Shoot and root extracts of charlock increased soluble and decreased non-soluble carbohydrate content in colza. Charlock aqueous extraction reduced protein and increased proline content in leaves. Shoot and root extracts of charlock at 1.5 % concentration increased catalyzed oxidation of Guaiacol (peroxidase activity) of leaf extract of colza.

In recent years, plants and biomolecules have been used in order to remove heavy metals from environment as an inexpensive and environmentally friendly method. In this research, cell wall matrix polysaccharide and its components, i.e. cellulose, pectin, hemicellulose A and hemicellulose B were separated and purified. The matrix and its polysaccharide components were treated with aqueous solutions containing 100 ppb Au in acidic, almost neutral and basic pHs for two different periods. The results of GFAAS showed that wall matrix and its polysaccharide components absorbed Au in all treatments. In neutral and basic pHs, cellulose; and in acidic pH, hemicellulose A; absorbed the lowest amounts of Au, while hemicellulose B showed the highest Au absorption in all pHs, during 1 h treatment with Au solution. Except for hemicellulose B which its ability for Au absorption and retention reduced by the time, in case of other components the amounts of English Abstracts of Farsi Papers absorbed Au increased along with increase the time of the treatments.

Baculovirus expression system has been used successfully to over-express eukaryotic proteins in insect cells. This system uses a very strong viral promoter, AcNPV polyhedrin, for high level protein expression. Here a Baculovirus expression system was used to express the Mouse Gaq protein (mGaq) in SF9 insect cells. The recombinant protein was made at high levels and it was found in the cell membrane where it functions as a signaling molecule.

Plants react to a virus infection at the molecular levels. These reactions are often accompanied by pathological changes on the cellular level and eventually become macroscopically visible as symptoms. Investigation of these modifications demonstrates the host biochemical responses. With the knowledge of these responses we are able to alleviate the pathogenicity of a pathogen with interfering in the different course of infection. This investigation was performed to study the cytological effect of Potato virus Y on tobacco plants (Nicotiana tabacum cv White Burley) chosen as a model plant. For this aim, leaf extract of infectious potato plants were mechanically inoculated to tobacco plants. Two weeks after inoculation and simultaneous with the systemic symptoms appearance, samples of mottel chlorotic areas (2-4 mm2) prepared and were fixed in glutaraldehyde, post fixation was accomplished by treatment with osmium tetroxide. After dehydration the specimens were embedded in spur medium, specimens were cut on ultra microtome. Sections were observed with light and electron microscope after staining with uranyl acetate and lead citrate. After viewing the specimens results were as follows: degenerated cytoplasms, nucleus was enlarged and became lobed, number and the size of mitochondria were increased, number and the size of chloroplasts were decreased and arrangement of thylakoides were messed, malformation and swelling the membrane of chloroplasts were also observed and increase in the proteinaceous chloroplast pigments (plastoglobuli) became obvious. Number of paramural bodies increased and we observed most often viral inclusion bodies along with the endoplasmic reticulum due to systemic infection. According to the results we conclude that respiration of infected cells increased and photosynthesis decreased and also metabolism system of host was become too activated due to the viral infection. Results indicate the hypersensitive response like mechanism involve in the systemic infection of potato virus Y.

This research deals with the seed contents of some varieties of Brassica napus (cvs. Ebonit, Bristol, VDH80001, Option, PF, Colvert, Orient, Cobra, IRA, Rigent ´ Cobra) using the following approaches: 1) measurement of the total seed protein which yielded protein content ranged from 18.46 to 30.8/100 gr of dry weight inVDH8001 and Bristol varieties, respectively; 2) study of seed storage protein using gel, electrophoresis; 3) extraction of the total seed oil yielding contents ranging from 37% to 44% gr/100 of dry weight in Rigent ´ Cobra and Cobra varieties, respectively; 4) determination of fatty acids contents and their kinds. Among five major isolated fatty acids, oleic and stearic acids have the highest and the lowest values, respectively. The genetic linkage among the seeds belonging to different varieties was investigated based on fatty acids as well as proteins.

To find a suitable surfactant for enhancing the solubility of fatty acid, some nonionic surfactants including Tween 20, 40, 60, 80, 85; poly-ethylene glycol 200, 300, 400, 600; di-ethylene glycol di-methyl ether (diglyme), Triton X-WO, tetrahydrofuran (THF) and dioxan were added to the fermentation medium (with or without palmitic acid) and their effects were studied on the morphology of Saccharopolyspora erythraea and erythromycin production. Tween 20 and Triton X-WO lysed the hyphae, but in the media containing other surfactants, the hyphae remained in a vegetative form. PEG 300, Tween 40 and THF had neither negative nor positive effect on the erythromycin production. But, addition of Triton X-100 and dioxan to the fermentation medium significantly decreased the concentration of erythromycin, 9.9 and 1.3 times less than that of control, respectively. In the media containing PEG 200, PEG 400, PEG 600, Tween 60, Tween 80, Tween 85 and diglyme, erythromycin concentration was 1.3, 1.5, 2.0, 1.4, 1.4, 1.3 and 1.3 times higher than that of control, respectively. Production of erythromycin in the palmitic acid containing medium was 1.62 times lower than that of control. However, the effect of palmitic acid on the erythromycin production was different when surfactants were added to media. Erythromycin production in the media containing palmitic acid plus PEG 400 and palmitic acid plus PEG 600 was more than that of palmitic acid containing medium (without any additional surfactant). However, erythromycin concentration in the media containing Tween 40, 60, 80 and 85, THF and diglyme was less than that of medium containing palmitic acid (without any surfactant).

When cultured on media containing various amounts of different hormones, plant organ segments can produce neoformed organs. Just like the organs produced from seeds, these neoformed organs can also go on to serve as intact plant organs. In this research, the seeds from three species of Hyoscyamus genus, including H. pusillus, H.  arachnoideus, annual H. niger and biennial H. niger from two different geographical regions, were cultured to obtain sterile seedlings. Then, organogenesis (rhizogenesis, caulogenesis, and leaf production) was assessed with the culture of seeds and organ segments of the obtained sterile plants on media containing various amounts of various hormones. Statistical assessments on the results showed us that the best rhizogenesis was obtained with root culture of biennial H niger, on MS medium containing IAA (0.2 mg/L), and tem culture of biennial H niger, on MS medium containing IAA (0.2 mg/L) and Kin (1.5 mg/L). Also, the culture of H pusillus, H arachnoideus, and annual H niger species on MS medium containing 2,4-D (0.32 mg/L) showed the highest rhizogenesis. The highest caulogenesis in biennial H niger species was obtained when the calli obtained from the stem ulture on MS medium containing IAA (0.09 g/L) and BAP (1.12 mg/L), were sub-cultured on MS medium containing BAP (1.12 mg/L) and GA3 (2.5 mg/L). Also the highest caulogenesis as observed on the calli obtained from the culture of the seeds of H pusillus on MS medium containing BAP (0.5 mg/L) and NAA (0.5 mg/L). The highest leaf production was bserved with the stem culture of H arachnoideus on MS medium containing Kin (1.5 mg/L), and the culture of H pusillus seeds on MS medium containing BAP (0.5 mg/L) and NAA (0.5 mg/L).

Experiments were conducted on four species of Quercus (Q. brantii, Q. infectoria, Q. castanifolia and Q. libani). Cotyledon culture using MS medium containing BAP and IAA was applied for callus production. In the medium with BAP (1.0 mg/lit) and IAA (2.0 mg/lit) all species produced callus, however, in this medium callus was produced after 8 weeks, after 12 weeks globular embryogenic nodules were observed on the surface of Q. castaneifolia calli and finally developed somatic embryos and plant regeneration. Stem and leaf culture did not produce any callus. No response was revealed in explants cultured on hormone free medium.

Donor plants were grown in a growth chamber at a day/night temperature of 15/10oC (16/8 hours). Microspores at late-uninucleate to early bi-nucleate were isolated from buds 2.5-3.5 mm in length and were cultured in NLN-13 medium containing 13% sucrose. 30 days after culture of isolated microspores, cotyledonary embryos with 4-5 mm diameter were transferred to Bs medium in order to regeneration. Cultured embryos were put at 4oC for ten days with the purpose of cold stress, and then were transferred to growth chamber at temperature of 25oC. After 30 days 3 traits, the percentage of normal plantlets regeneration, callogenesis and secondary embryogenesis were investigated. The method of embryogenesis with 3 levels was experimental treatment, embryo production in 1 L flasks containing 100 ml culture medium, in 0.5 L. flasks containing 25 ml culture medium and in glass Petri dishes 100x15 mm containing 12/5 ml culture medium. The results showed significant differences (a= 1%) between produced embryos in various containers forpercentage of normal plantlets regeneration, callogenic embryo production and secondary embryogenesis. The comparison of means showed that 1 and 0.5 L. flasks were the best effective containers for normal plantlets production (group a, 58% and 54%, respectively). Embryos in 1 L flasks showed the least abnormal regeneration with 21.41% callogenic embryos and 11.11% secondary embryos.

High concentrations of tellurium solutions have acute and chronic effects on living things. Attempt was made to find a biological method for the removal of tellurite from environments nd to determine the effects of different environmental factors on the removal of tellurite including pH (5.5-10.5), temperatures (25-45 oc), various oncentrations of salts (NaCl, KCl, N2SO4, 0.5-4 M), selenooxyanions (2-10 mM), at different concentrations of potassium tellurite (0.5-1mM) in aerobic condition by a gram positive; moderately halophilic bacterial strain nglish Abstracts of Farsi Papers 55 isolated from the Merinus Textile Factory effluent. On the basis of morphological, physiological and biochemical characteristics, the isolate was tentatively placed in the genus Salinicoccus. Maximum tellurite was removed at pH value of 7.5, temperature 35 oC, 1.5 M NaCl, 0.5 M Na2SO4, 1 M KCl, 6 mM sodium selenite. Concentration of the toxic potassium tellurite in the supematant of the bacterial culture medium decreased from 0.5 mM to .005 mM after 6 days of incubation period (%99) and color of the medium was changed to black, due to the formation of elemental tellurium (less toxic). Presence of crystal elements within the bacterial cytoplasm was observed by TEM and confirmed with using EDS analysis.