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31.
Ahmed Almehdi Ihsan Shehadi Mohamed El-Naggar Ismail Saadoun Kareem A. Mosa 《International journal of phytoremediation》2019,21(12):1254-1262
AbstractCalotropis procera is a perennial big shrub that has the potential to accumulate high concentrations of heavy metals. Metal sequestration in old organs has been considered as a mechanism for plant survival in polluted soils. The aim of the present study was to assess the role of the old leaves as a sink for HMs accumulation in C. procera. Two instruments were used: atomic absorption spectroscopy (AAS) and X-ray fluorescence (XRF) microscopy. Soil and plant samples were collected from around one of the worst congested traffic areas in the United Arab Emirates (UAE). Samples from roots, stem, and green and old leaves were prepared and analyzed by both instruments. Calotropis procera was able to concentrate Fe, Mn, Sr, and Zn in the roots, but their translocation to stem and green leaves was low. Old leaves had greater ability to accumulate significantly higher concentrations of different metals, especially Fe and Sr, than other parts of the plants, indicating that C. procera uses these metabolically less-active leaves as sinks for heavy metals. Fe and Sr attained higher bioconcentration and accumulation values, compared to Zn and Mn. There were significant positive correlations between XRF and AAS for all elements in the different organs. 相似文献
32.
The Bacillus subtilis ATCC 6633 strain synthesizes a mutagenic metabolite from sodium azide and O-acetylserine. Mutagenicity of azide was decreased in growth media containing 10(-4) M glutathione, L-cysteine or L-djenkolic acid whereas dithiothritol (DTT) added at the same concentration did not reduce the mutagenicity of azide. Likewise, glutathione, L-cysteine, L-djenkolic acid, and DTT were found to have no effect in reducing the mutagenicity of the in vitro produced metabolite using bacterial cell-free extract. These results suggest that O-acetyl-serine sulfhydrylase catalyzes the reaction of azide and O-acetylserine to form a mutagenic metabolite, which is ninhydrin positive and migrates in TLC to an Rf value similar to that of azidoalanine in both acidic and basic solvent systems. 相似文献
33.
Amjad A. Mahasneh Jazi D. Odat Ban M. Al-Joubori Ismail Saadoun 《Saudi Journal of Biological Sciences》2021,28(8):4500-4510
This investigation aimed to determine the relatedness of dominant occurring soil Streptomyces spp. in Northern Jordan based on their RAPD-PCR fingerprints, and to compare RAPD technique with the conventional phenotypic characterization of Streptomyces isolates. Fifty-eight white and gray color-bearing aerial mycelia antibiotic active-producing Streptomyces soil isolates along with three reference strains were genetically analyzed by RAPD-PCR. Polymorphisms between the isolates showed 1 to 10 bands per isolate and ranged from 200 to 3200 bp in size. Results revealed one common band of ~600 bp shared by ~85% of the isolates, and the observation of bands specific to some reference strains and some soil isolates. When RAPD patterns were analyzed with the UPGMA, results revealed clustering the tested isolates into two equal main super clusters (50% each). Super cluster I appeared to be homogenous and include the three reference strains. However, super cluster II was heterogeneous and but not including any of the reference strains. The association of the antibiotic activity of the dominant white and gray aerial mycelium-bearing Streptomyces isolates to RAPD clustering is reported for the first time, and the RAPD-PCR fingerprints generated here deserve to be cloned, characterized and sequenced in future as Streptomyces species-specific DNA markers. The more random primers used in the analysis may add to RAPD technique a cost-effective, fast, precise result, and less labor work solution for analyzing the similarities and differences among the Streptomyces isolates. 相似文献
34.
Plasmids or covalently closed circular (CCC)-DNA molecules are abundant in the genus Streptomyces, and have been suggested to be involved in the genetic control of the production of many antibiotics in these organisms. In this study, 21 active antibiotic-producing Streptomyces isolates were screened for their plasmid content by an alkaline lysis method which revealed the presence of a small plasmid DNA in the positive control Streptomyces lividans ATCC 35287, containing pIJ702 plasmid (5.65 kb in size). However, no low molecular weight plasmids were observed in the tested antibiotic-producing Streptomyces strains suggesting that antibiotic production in these strains is likely chromosomally encoded DNA. Treatment of 2 Streptomyces strains with 10 mM ethidium bromide (EB) resulted in the failure to produce aerial mycelia and antibiotic activity. 相似文献