مجله علوم دانشگاه تهران
سال سی و سوم شماره 4 (زمستان 1386)

Steatoda paykulliana has never been recorded from Iran.In the present study, for the first time it is recorded from Khorasan province, Iran. This species previously has been reported from Europe, northern parts of Africa and Middle East. In this study some new data on taxonomy, geographic distribution and habitats of this species has been provided.

Among the 22 strains of moderately halophilic bacteria isolated from saltern soils, the isolate MAM tolerated salt and grew well in nutrient broth containing 0.5-32% salt. Preliminary experiments revealed that the strain was highly resistant to oxianions. Agar dilution method was used to measure tolerance of the strain to metal (KCrO4, NaCrO4) and metalloid (Na2SeO4, Na2SeO3, Na2HAsO4, NaHSeO3, K2TeO3) oxianions. All tests were performed in nutrient agar plates with 5, 10, and 15% salt and incubated at 32? C. The results obtained, showed that the isolate can tolerate the oxianions tested up to the following concentrations: Arsenate 450 mM, selenate 400 mM, selenite 450 mM, biselenite 150 mM, chromate 25 mM, tellurite 1 mM. The data obtained proved that sodium plays an important role in bacterial growth, and also in tolerance to the oxianions tested. The strain MAM was able to grow in the presence of 25 mM sodium chromate but could not grow in potassium chromate in concentrations higher than 20 mM.. It is worth to emphasis that the strain tolerated tellurite and selenite and reduced the oxyanions also, producing black and dark red colonies due to the intracellular accumulation of the elemental tellurium and selenium. When potassium tellurite was used in combination with sodium selenite, the strain could tolerate up to 20 mM concentration of tellurite ions.

The rat pituitary cell line, GH3, and its subclones secret significant amounts of prolactin (PRL). The GH3/B6 cells are generally grown in Ham's F12 medium supplemented with 15% horse serum and 2.5% fetal calf serum. In routine conditions, the doubling time of GH3/B6 cells varies from 30 to 52hr, depending on the qualities of the serum. The GH3/B6 cells are used to study the effects of several hormones on prolactin secretion. The recent works have shown that pectic acid increases secretion of prolactin. Pectic acid releases stored prolactin in cells and after a short time it appears to be effective. After being incubated with pectic acid for 30 minutes the cells started to become circular, protuberant shape and entered the secreting phase. pectic acid had not significant effect in number of cells but a decrease in total amount of protein was observed. After pectic acid was added, a significant decrease happened in the medium pH and this decrease caused unfavorable condition for cells. To solve this problem, the medium with Hepes was used. Hepes had been used extensively in cell culture due to its excellent buffering capacity in the physiological range. After a while; however, the cells appearance changed, their growth decreased, cytoplasmics vacuoles and membrane inclusion bodies developed and the viability decreased. Hepes stimulates the production of toxic oxygen metabolites such as hydrogen peroxide which itself results in a decrease in growth of GH3/B6 cells. Consequently, Hepes was replaced by NaOH in this experiment. NaOH had no effect on the cells and the pH was adjusted in 7.2.

Abscisic acid (ABA) is a stress hormone that plays multifunctional roles in adaptation of plants to stressful environments. An optimal increase of internal ABA concentration of leaves causes water saving through stomatal closure. In order to explore the effect of drought stress on leaf tissue ABA concentration and stomatal resistance of chickpea, a greenhouse experiment was conducted using five genotypes (Three tolerant genotypes including: ICCV93040, MCC13, MCC10 and two sensitive genotypes consisting of: MCC120 and MCC180) and two levels of water availability, growing at field capacity and at 25% of field capacity. Seeds were sown in 50 × 12 cm plastic tubes which were filled by washed sands. Nutrient elements were prepared using Hoagland nutrient solution. Leaf ABA concentration, determind using High Pressure Liquid Chromatography (HPLC). Results showed that drought stress imposed an increase in leaf ABA content up to flowering, but after this stage, leaf scenesence caused a reduction in leaf ABA. Genotypes showed different ABA concentrations and stomatal resistances in the presence of drought stress. The highest and lowest amount of ABA were observed in MCC13 (drought tolerant) and MCC120 (drought sensitive) respectively. ABA concentration of MCC13 and MCC120 were 29 and 3ngg-1 (fw) which is a 10 fold difference between them. Stomatal resistance of tolerant genotypes were more than sensitive ones, in sress and non-stress conditions. A significant positive correlation between leaf stomatal resistance and ABA concentration were observed (r = 0.87), but in non-strss conditions this relationship was not significant (r = 0.21).

The objective of the proposed study is predicting structural classes of proteins in two states (all-? and all-?). We used a two-stage hybrid model constructed of artificial neural networks (ANN) and logistic regression model (LRM). The LRM was initially used to extract the effective variables (n=7) from the generated structural variables (n=662) in order to simplify the structure of the ANN which intended to predict the structural classes of proteins. The predicting structural classes of proteins performed on one non-homologous mono-domain globular proteins data set (n=104). Among the 20 evaluated single amino acid composition frequencies Valine and Glycine frequency were statistically significant (P<.05) according to the result of LRM. Similarly among the 400 evaluated dipeptides composition frequencies the Lysine-Proline, Glutamine-Proline, Isoleucine-Serine and Serine-Glutamine frequencies were also significant. Among the 22 evaluated tripeptides frequencies only Asparagine-Leucine-Aspartic acid composition frequency was significant. The prediction of the proteins structural classes in two states (all-? and all-?) performed 88% only based on seven significant structural variables among 642 structural variables. In this study, both threshold dependent and independent (ROC) measures have been used for performance evaluation of the established hybrid model.

The present study was carried out in order to complete taxonomic survey on Iranian freshwater amphipods in East Azarbaijan, West Azarbaijan and Ardebil provinces. The results revealed that amphipods of Azarbaijan of Iran belong to family Gammaridae with two genera namely, Obesogammarus and Gammarus. Obesogammarus turcarum is restricted to the Caspian Sea drainage basin and was found along Aras River. Three species including Gammarus komareki, G. lacustris, and G. paricrenatus belong to G. pulex species group. Based on results of the present study, G. komareki was the dominant species. From zoogeographical point of view, G. komareki was found in Asia minor. Compared to the other two species, G. lacustris is distributed in the northern parts of America, Europe and Asia. Gammarus paricrenatus is endemic to Iran and in one locality was sympatrically observed with Gammarus lacustris.

Iron is one of the effective constraint in plants that its role in enzyme activation has been identified. This investigation was done with basil (ocimum basilicum) in vegetative stage. Addition of iron to the soil of basil was carried out with 21 ppm during 6 days. The growth plant and the composition of its essential oil was subjected to study. Increasing iron supply resulted in decreased plant growth. The major compounds of essential oil of control plants were methyl chavicol, geraniol and nerol, respectively. However after treating with iron, the relative content of methyl chavicol was decreased, compared to the content of geraniol. The amount of caryophyllene oxide in treated plants was significantly higher than it in control plants. It can be concluded that excess iron supply reduced both growth of basil and the yield of its essential oil.

The effect of different culture media and 6-Benzylaminopurin (BAP) concentrations on direct adventitious shoot formation in Pinus eldarica zygotic embryo explants were evaluated. Statistical analysis of data showed a significant media and BAP concentration effect on shoot meristem induction. Among the used basal media, Le Poivre (LP) medium supplemented with 5 mg/L BAP proved to be most suitable for multiple shoot formation. The caulogenesis occurred mainly on the basal portions of the cotyledons and without any obvious intermediate callus formation. However, the shoot regeneration process involved the identification of either shoot meristems or caulogenic nodules on the surface of cultured embryos. Histological sections confirmed the direct formation of these discrete structures on the explants. All of the adventitious shoot meristems showed normal cell organization. This in vitro procedure could be useful for studies on efficient plant regeneration of Pinus eldarica.

Effect of peanut (Arachis hypogaea) seed flour and its fractions on the growth of Streptomyces clavuligerus and clavulanic acid production in media containing soy meal, malt and mineral salts as the main substrates, was investigated. Peanut seed flour increased the clavulanic acid production by S. clavuligerus. Concentration of clavulanic acid in the media containing peanut seed flour, peanut meal, peanut oil, glycerol, peanut meal + glycerol, peanut protein + glycerol and control were 657, 391, 459, 463, 614, 668 and 467 mg/l, respectively. Concentration of clavulanic acid in the media containing peanut protein + glycerol and peanut seed flour were the most and clavulanic acid production in these media were 43% and 40% more than that of control, respectively. It was concluded that peanut and its fractions can use as suitable nitrogen and carbon sources for clavulanic acid production.

The effects of salinity on some growth parameters, protein content and antioxidant enzymes were studied in three Acanthophyllum species of different ploidy levels including A. laxiusculum Shiman-Czeika (diploid species with 2n = 30), A. sordidum Bunge ex Boiss. (tetraploid species with 2n = 60) and A. glandulosum Bunge ex Boiss. (hexaploid species with 2n = 90). Seedlings of the species were subjected to NaCl stress (50, 100, 150 and 200 mM) for 40 days. Salinity affected the growth parameters and caused a reduction in germination percentage, relative growth rate (RGR) and relative water content (RWC) with a greater reduction in A. laxiusculum. However, salinity stress caused only slight decrease in RGR and RWC of A. glandulosum and A. sordidum. Protein content in both A. laxiusculum and A. sordidum increased up to 150 mM NaCl, but this increase in A. glandulosum occurred at 150 and 200 mM NaCl. A. laxiusculum exhibited a decrease in peroxidase (POX) and polyphenol oxidase (PPO) under NaCl stress; while A. glandulosum showed a remarkable increase in POX and PPO between 50 to 200 mM NaCl. In A. sordidum, POX and PPO activities increased at 50 mM NaCl and then decreased at higher salinities. The obtained results showed that the differences in the antioxidant enzyme activities of seedling may, at least in part explain the greater tolerance of A. glandulosum comparing to A. sordidum and A. laxiusculum. According to our results, A. glandulosum (hexaploid species) showed a better protection mechanism against salinity induced oxidative damage than A. sordidum (tetraploid species).

Regenerated plantlets were obtained from Ferula assa-foetida (Apiaceace) through indirect and direct somatic embryogenesis, for the first time. Callus was induced on hypocotyl explants from seedlings of two ecotypes (Shirkooh and Tabas) on Murashige and Skoog (MS) basal medium supplemented with 0.5-4 mg/L kinetin along with 0.1-1 mg/L? -naphthalene acetic acid (NAA) for 12 weeks. Embryogenic calli developed within 4 weeks after transferring the calli to hormone-free MS medium. Induction/maintenance MS medium supplemented with 1.5 mg/L kinetin and 1 mg/L NAA was most effective and provided a high embryogenesis frequency (31%) associated with a large mean number of mature somatic embryos per explant (8.4) in Tabas ecotype. According to our data, the presence of kinetin in the callus induction medium with NAA enhanced subsequent differentiation of somatic embryos on the hormone-free medium. About 40-50% of regenerated somatic embryos germinated into complete plantlets. Direct somatic embryogenesis without an intervening callus phase was induced from intact seedlings on hormone-free medium within 12 weeks. Embryo induction was observed all over the seedling surface with the highest numbers on hypocotyl segments. By this procedure, the maximum mean number of embryo per seedling was 42 in Shirkooh ecotype and more than 50% of cotyledonary embryos were developed not only into normal plantlets, but rooted simultaneously when cultured on hormone-free MS medium. Also, histological observations revealed different stages of embryogenicity such as globular, heart, torpedo, and cotyledonary stages in F. assa foetida.

Here we report the change in glycodecoration of the oocyte during with folliculogenesis. Five peroxidase-conjugated lectins were used to study their ability to bind to the oocyte at the successive developmental stages. During oocyte maturation process sugar parts of the glycoconjugates from zona pellucida undergo directed biochemical changes to provide glycan configuration suitable for their important physiological functions. In this study we report presence of terminal and accessible sugar moieties of the zona pellucida through sharp distinguishable differences against background of the oocyte by using five peroxidase conjugated lectins. Lectin binding features of the successive stages of the developing zona pellucida through staining with lectins revealed the absence of mannose and non-acetylated forms of galactose and glucose termini and conversely importance of the N-acetylated derivates for both of galactose and glucose as a speculative remark on oocyte maturation process. Moreover presentation of the? -anomers precedes? -anomers in the mentioned sugar termini, based on observed DBA (lectin derived from Dolichos biflorus) and PNA (lectin derived from Arachis hypogaea) binding capacity.