مجله ایرانی علوم و تکنولوژی-الف
سال:1381 | دوره:27 | شماره:1-الف |تعداد مقالات:23

Tomato plants (Lycopersicon esculentum Mill.) were grown in potted soils exposed to six salinity levels (0, 3, 5, 7, 9 and 11 dS/m), four salt compositions (C1= 100% NaCl, C2=60% NaCl and 40% Na2SO4, C3=40% NaCl and 60% Na2SO4 and C4=100% Na2SO4 on chemical equivalent basis) and four zinc (Zn) levels (0, 5, 10, and 20 mg/kg as ZnSO4, 7H2O). Proline did not start to accumulate in tomato leaves up to the soil salinity of 7 dS/m, and above this threshold, it increased linearly with increasing salinity. However, plants exposed to C1 treatment contained more proline than those subjected to the other salt compositions. Furthermore, proline did not accumulate until concentration of Na in tomato leaves reached a threshold values of 0.40, 0.38 and 0.25% for C1, C2 and C3 salinity regimes, respectively. The results of the present study indicate that sugar concentration decreased by increasing soil salinity and increased with Zn application. The harmful effect of Cl and Na accumulation on sugar metabolism and/or a rise in the plant respiration might have been responsible for such salt stress behavior. Although, salt treatment lowered transpiration rate and leaf area, a given increment of soil salinity produced a larger decrement in leaf size in C1-treated plants than in tomato seedlings exposed to C4 salinity regime. Finally, our results indicated that Cl accumulation was more toxic to tomato growth than that of Na.

Metabolic hormones are good indicators for malnutrition. Effects of a different dietary energy and protein ratios on plasma concentrations of growth hormone (GH), thyroxine (T4) and triiodothyronine (T3) in male broilers were determined. Broilers were fed either 2800 or 3200 Kcal/Kg diet with 128, 133.3, 139.1, 145.5 and 152.4 energy and protein ratios for starting period, 145.5, 152.4, 160. 168.4 and 177.8 energy and protein ratio for growing period and 160, 168.4, 177.8, 188.2 and 200 energy and protein ratios for finishing periods, respectively. Blood samples were collected from wing vein at the end of starting, growing and finishing periods. Blood samples were kept at 4°C until centrifugation. A saturated sodium citrate solution (40 یl of sodium citrate solution/ml blood) was added to the samples before centrifugation to prevent clotting of plasma during storage. Plasma was stored at 20°C until assayed for GH, T4 and T3 by RIA. Body weight and feed conversion were also measured at the end of starting, growing and finishing period. Mean concentrations of plasma GH were significantly higher (P<0.01) in broilers fed 2800 Kcal/Kg diet than those fed with 3200 Kcal/Kg during starting, growing and finishing periods. Mean concentrations of plasma GH were not changed in broilers fed with different protein levels during starting, growing and finishing periods. Mean concentrations of plasma T3 were significantly lower (P<0.01) in the broilers fed 2800 Kcal/Kg diet than those fed with 3200 Kcal/d during starting, growing and finishing periods. Mean concentrations of plasma T4 did not changed in the starters, growers and finishers, fed either with 2800 or 3200 Kcal/Kg diet. Different protein levels did not change the mean concentrations of T4 and T3 among starters, growers and finishers. The result of this experiment indicates that different protein levels during starting, growing and finishing periods in broilers may not change the plasma concentration of GH, T4 and T3. The low energy intake may increase mean plasma concentrations of GH and decrease mean plasma concentrations of T3.

The most striking effect of silver nitrate (AgNO3) was the production of a yellow body color in wild type of Drosophila melanogaster. The optimum concentration of this salt, required to induce 100% expressivity of the yellow body phenocopy, was determined to be 0.20% of the live yeast available as food in the medium. This amount of silver nitrate was equal to 6.4 یg per larvae. The females showed more sensitivity to the effects of silver nitrate than males. Transferring the yellow body flies to normal medium proved that the trait was not inherited in the next generation and had no genetic basis. The phenocritical period of silver nitrate apparently was within the first instar and initial hours of the second instar larval stages.

Morphological identity among different Aegilops spp. stipulates the necessity of using new characteristics to distinguish these species. Anther length represents breeding systems of the taxon, which could be useful in individualizing species groups. Our observations on 68 populations belonging to 10 species of Aegilops showed that Ae. crassa Boiss., Ae. tauschi Coss., Ae. geniculata Roth. and Ae. columnaris Zhuk. are inbreeders, while others are breeders. Anther length hasn’t efficiency in discerning two varieties of Ae. triuncialis L. Most species of Aegilops in Iran are outbreeders and a wide range of interpopulational and intraspecific variations confirm this conclusion.

In this article, the immobilization of submitochondrial particles to immobilize submitochnodrial particles (SMPs) on Fractosil-1000 by hydrophobic adsorption is reported. SMPs were prepared from beef liver mitochondria and the catalytic activity of succinate-cytochorome c reductase succinate cytochrome c reductase (SCR), multienzymatic complex of inner-mitochondrial membrane, was used as an example of its catalytic potential. The effects of membrane particles concentration and the pH of the buffer on adsorption of SMPs and the effects of buffers were explored. The response of free and immobilized membrane preparations to changes in pH and the stabilization of SMPs in different pH values were also followed. The results revealed that the best condition for the adsorption of SMPs was approximately 14-16 mg SMP per gram of Fractosil-1000 in MPTG buffer (containing 20 mM each of mes, pipes, trizma and glycine at pH of 7.0) at 4°C. It was also observed that immobilization of SMPs had no effect on the optimum pH of the enzyme (pH 7.0) in both immobilized and free forms. However, the activity profiles of free and immobilized preparations were different in acidic and basic environment

The purpose of the present investigation was first, to study the reaction of the sulfhydryl groups of rhodanese with different disulfides; and second, to determine the effect of these disulfides on the cyanide metabolism in mice. Several disulfides with different chemical properties were allowed to react with the sulfhydryl group in the active site of rhodanese. The Ellman reagent; 5,5-dithiobis (2-nitrobenzoic acid), DTNB, reacted very slowly. A marked increase in the rate of reaction of rhodanese with DTNB was observed when cystamine or cystine were present. No change was seen with disulfides dimethyl disulfide, 2-hydroxy ethyl disulfide, dithioglycolic acid, oxidized glutathione, 2,2- dithiosalicylic acid, 2,2-dipyridyl disulfide (2-PDS) and 4,4-Dipyridyl disulfide (4-PDS). A Km of 2.0 and 2.5 mmol/L was obtained for cystamine and cystine, respectively, whereas the Km for thiosulfate, the common substrate of the enzyme was 3.0 mmol/L. LD50 for subcutaneous administration of potassium cyanide and intraperitoneal injection of cystamine hydrochloride were 11.5 and 350 mg/kg body weight (bw), respectively. Sodium thiosulfate reduced mortality of cyanide to 20% or 30% when administered 10 min before or 10 min after cyanide, respectively. Cystamine hydrochloride administration at 250 mg/kg body weight 10 min before or 10 min after cyanide injection increased mortality to 70% or 100%, respectively. Taken together, the results indicate that certain disulfide, such as cystamine, which show enhanced reactivity with sulfhydryl group(s) of rhodanese in-vitro, might also react with sulfhydryl group(s) of rhodanese in-vivo and impair the rhodanese mediated detoxification of cyanide.

The ripe fruits of milk thistle (Silybum marianum (L.) Gaertn), which contain flavonoids, are used to prepare anti-hepatotoxic drugs. The influence of sowing dates comprising of September 11 and October 17 as fall planting, March 10 and April 12 as spring planting, and plant density consisting of 8.0, 6.7 and 5 plants per m2 on the productivity (growth, seed yield and active substances) of milk thistle were examined. The small plot experiment was installed in the experimental station of Paykan Shahr belonging to the College of Agriculture of Tarbiat Modarres University located in the suburb of Tehran, Iran. The results showed that the best time for sowing of milk thistle was in the fall especially in September. The most suitable plant density was 50×30cm (1500 cm2 per plant, 6.7 plant per m2). The stepwise multiple regression analyses verified that 89% of the changes in the seed weight per plant was explained by seed yield, 98% of the changes in the yield of silymarin was defined by seed yield and 96% of the alterations in the yield of silybin was explained by silymarin yield.

Responses of brain cytosolic and microsomal glutathione (GSH) Stransferases (GSTs) to the effects of various doses of theophylline have been investigated in adult and suckling rats. Normally cytosolic GSH content and activities of GSTs were higher in adult brain as compared to those in growing rats. Different doses of theophylline (10, 20, 30 and 50 mg/kg b.w) have been examined and comparative studies have been carried out with a dose of 50 mg/kg. A single i.p dose of the drug resulted in a maximum 25 and 55% depletion in cytosolic brain GSH in adult and suckling rats, respectively. Depletion of GSH in brain of adult and growing rats was noticed 4 hrs after theophylline injection, but the time of re-synthesis was relatively slow in the developing brain. It is interesting to note that the level of GSH remains significantly high for at least 24 hrs after theophylline injection in the growing brain. Additionally, brain microsomal and cytosolic GSTs have been induced (p<0.05) due to theophylline, in suckling rats as compared to those of adults. The maximum rate of induction of both cytosolic and microsomal GSTs in growing brain was 1.8 and 2.7-times, respectively. These results together with SDS-PAGE data obtained from the analysis of affinity-purified GSTs, showed that the pattern of changes in GST classes in both age groups is different. In addition to microsomal GST, α-class of cytosolic enzyme (GST-α) is differentially induced in the brains of the two age groups in response to theophylline. It is suggested that the response of glutathione system is implicated in the protection against theophylline-mediated oxidative stress due to the bulk of the drug, which is believed to cross-underdeveloped blood-brain barrier in immature rats.  

Mannitol and salicylic acid were tested for their effects on the synthesis of (+)-catechin, an antioxidant molecule abondantly found in tea (Camellia sinensis L.) (+)- catechin level decreased in callus tissues which were cultivated on Murashige and Skoog medium with the addition of salicylic acid (1, 5, 10 یM). The presence of mannitol (30g.L-1) in the culture medium induced a high accumulation of (+)-catechin (5-fold increase) and anthocyanins (29-fold increase) in the tea callus tissues after ten days. Salicylic acid (1یM) strongly inhibited the (+)-catechin synthesis triggered by mannitol.

Spheroplast were prepared from a carotenoid pigmented morpholine degrader Mycobacterium (Mor+) and one none pigmented piperazine degrader Mycobacterium (pip+). The recombinants were selected on the basis of morpholine and piperazine degradation. Wall-deficient forms of Mycobacterium (strains mor+ and pip+) were prepared by agitating the cells during mid exponential growth with glycine, cycloserine, lysozyme and EDTA for approximately 18 hrs. wall deficient forms were then converted to spheroplasts by gentle stirring with lysozyme and EDTA in a Tris/HCl buffer containing sucrose until all of the cells appeared spherical by phase contrast microscopy. Spheroplasts of the two strains were mixed in a 1:1 ratio and were treated with 40% (w/v) polyethylene glycol 6000 for 10 min at 37°C. Protoplast regeneration was accomplished in appropriate hypertonic media containing alanine. The frequency of Mor+ Pip+ recombination in optimal condition was about 12%. The results were further confirmed by analysis of the plasmid profile of hybrid strains.

Pyruvate depedent histidine decarboxylase from Lactobacillus 30a (EC 4.1.1.22) was used and IC50 values were determined for four new imidazolidine 4-one derivatives as inhibitors of the enzyme. 2,2-dimethyl-5-phenyl imidazolidine-4-one (DMPI), 2-ethyl-2-methyl- 5-phenyl imidazolidine-4-one (EMPI), 5-Phenyl-1,3- diazaspiro [4,4] nonane 4-one (PDAN) and 5-phenyl-1,3-diazaspiro [4,5] decane-4-one (PDAD) showed decreases in inhibitory activity as the size of C2 substituent on imidazolidine 4-one derivatives increased. The activation of enzyme occurred with the compounds that contained largest substituent. Correlations existed between log IC50 and the molecular diameter as established by computer aided estimations.