RESEARCH JOURNAL OF UNIVERSITY OF ISFAHAN "SCIENCE"
Year:2005 | Volume:22 | Issue:2|Papers Count:8

Considering biological fertilizer for non host plant, the effect of different compounds and root exudates on chemotaxis of two strains isolated from sugarcane and meliloti was examined. The presence of 1mM EDTA increased the chemotaxis of Rhizobium to Malic acid while decreased principle attractant to Aspartate. The Rhizobium was most attracted to Amino acids while Acetobacter was attracted to Cytokine and Jibereline. The presence of Mu, Zn cationic and NaCl in appreciable concentration reduced the movement of Rhizobium to roots.

The eukaryotic cells have one or more nucleolus in the nucleus. Saccharomyces Cerevisiae has a crescent nucleolus close to the nuclear envelope into which part of chromosome XII including repeated units of the rDNA genes is transported into crescent nucleolus of yeast. Studies on the recombination at this region show some crossing over between sister chromatid of chromosome XII. However, non-sister chromatid exchange of homologous chromosome XII is not observed at the rDNA region, suggesting in suppression of double-strand breaks (DSBs) at that region. It has been suggested that silencing proteins including Sir2 have important role in silencing state of chromatin for recombination. We studied the occurrence of DSBs at the rDNA region using pulse field gel electrophoresis via CHEF technique and restriction enzymes which cannot cut within the rDNA unit. DSB's fragments were detected using an specific rDNA probe in Southern blot technique. Despite previous suggestions, results show some breaks in the nucleolus, which cannot be detected using recombination techniques. This suggests that ultra structure of chromatin in the nucleolus is completely different compared to that of the nucleus.

"Garsoom" is a kind of branch wilt which occurs in different Citrus species in Fars province. It appears usually in autumn and progresses within 10-14 days. Morphological and histological studies were performed on healthy and wilting branches of sweet orange [Citrus sinensis (L.) osb.]. Affected branches showed visual and successive symptoms such as: rolling of green leaves, leaf fall, cracking of branches accompanied with gum extrusion, gradual browning and wilting of branches. Branch wilt was a reflection of changes in the xylem tissue. Filamentous or/and amorpholls plugs occluded the vessel member, partially or completely. A relation was also found between the gradual symptom development and histological changes: Occlusions were mostly filamentous in the primary xylem during early stages of the disorder. Xylem plugs increased significantly in number, as the disorder progressed. They were mostly of amorphous type, and were found in the secondary xylem. Occlusions were also observed in different parenchyma and fiber cells of the xylem tissue. Morphological and structural aspects of "Garsoom" are compared to other Citrus decline diseases.

In order to survey on morphometrical differences, 28 great tit Parus major were caught during January 2002 to May 2003 from two localities. Noor forest park (Noor) and Abbasabad gardens in southern slope' or Alvand mountain (Hamedan) by mist net and gun. 29 morphometric characters among two populations have been compared based on univariate and multivariate analyses using SPSS and Past.Comparing biometric and morphologic data revealed that, 16 characters among two populations show significant differences (p<0.05). Final results from statistical analyses show that these populations are different and they are two ecotype.

Milk has been considered as one of the unique sources for children and even adults nutrition. In accordance with the present survey and studies the amount and level of Hg, Pb, Cd, and Cr has been specified in the cow milk. In order to measure the poisonous metals of milk, four digestion methods have been experienced. Organic matter is digested with nitric acid, hydrogen peroxide and perchloric acid; the most suitable acids in wet digestion of milk. Mercury was determined by the Cold Vapor Atomic Absorption method, following acid digestion. Mercury was undetectable in milk samples (< 0.05 ppb). A method for determination of Pb, Cd, and Cr in milk consists of extraction in MIBK of the complexes formed with APDC and further analysis of the extracts by Flame AAS. The results showed that the mean concentration of Pb, Cd, and Cr were 49.1±6.62, 9.8±0.36 and 38.8±0.58 (ppb) respectively. This indicates that 72.5% Pb and 6.8% Cr concentration were higher than the maximum levels recommended. The consequences have shown us that Lead and Chromium causes dangerous effects on human organs, and we should do our best to decrease the amount of the above mentioned metals.

This investigation is concerned with photochemical degradation of sulfanilic acid. This substance is largely used in textile and dye industries, a part of which is discharged in the wastewater. A jacketed circulating reactor, equipped with direct imposed irradiation has been designed and used in this work. The concentrations of substrate have been determined using an ultraviolet-visible spectrophotometer. The experimental data has been obtained for each run after adjustment of pH and temperature of operation. The irradiation time has also been controlled. There is an optimal pH»4 (close to substrate concentration of 10 ppm) for which the maximum conversion is obtained. A 30 min irradiation time, for example, was sufficient for complete removal of substrate with 10 ppm initial concentration. The significant decrease of COD and the significant removal of the carbon - carbon double bonds observed in the FT-IR spectrum indicate that the degradation is consistent with mineralizing of the organic substrate (conversion of benzene ring to carbon dioxide and water, conversion of sulfite group to sulfate and conversion of amine group to nitrate). The method of degradation of sulfanilic acid could therefore have useful industrial applications.