Testing the covarion hypothesis of molecular evolution

The covarion hypothesis of molecular evolution states that the fixation of mutations may alter the probability that any given position will fix the next change. Tests of this hypothesis using the divergence of real sequences are compromised because models of rate variation among sites (e.g., the gamma version of the one-parameter equation) predict sequence divergence values similar to those for the covarion process. This study therefore focuses on the extent to which the varied and unvaried codons of two well-diverged taxa are the same, because fewer are expected by the covarion hypothesis than by the gamma model. The data for these tests are the protein sequences of Cu, Zn superoxide dismutase (SOD) for mammals and plants. Simulation analyses show that the covarion hypothesis makes better predictions about the frequencies of varied and unhit positions in common between these two taxa than does the gamma version of the one-parameter model. Furthermore, the analysis of SOD tertiary structure demonstrates that mammal and plant variabilities are distributed differently on the protein. These results support the conclusions that the variable and invariable codons of mammal and plant SODs are different and that the covarion model explains the evolution of this protein better than the gamma version of the one-parameter process. Unlike other models, the covarion hypothesis accounts for rate fluctuations among positions over time, which is an important parameter of molecular evolution.      

Sterigmatocystin — incidence, fate and production byA versicolor in ras cheese

Sterigmatocystin (STG) is a toxic metabolite produced by severalAspergillus species. Because of its toxic and carcinogenic properties the occurrence of STG in food is considered to represent a potential hazard to man. The present study was designed to investigate following points:

The predictive value of transcranial duplex sonography for the clinical diagnosis in undiagnosed parkinsonian syndromes: comparison with SPECT scans

Background  

Transcranial duplex sonography (TCD) of the substantia nigra has emerged as a promising, non-invasive tool to diagnose idiopathic Parkinson's disease (IPD). However, its diagnostic accuracy in patients with undefined parkinsonism remains to be determined.     

Phycoremediation of phenol-polluted petro-industrial effluents and its techno-economic values as a win-win process for a green environment,sustainable energy and bioproducts

The discharge of the toxic phenol-polluted petro-industrial effluents (PPPIE) has severe environmental negative impacts, thus it is mandatory to be treated before its discharge. The objective of this review was to discuss the sustainable application of microalgae in phenols degradation, with a special emphasis on the enzymes involved in this bioprocess and the factors affecting the success of PPPIE phycoremediation. Moreover, it confers the microalgae bioenergetic strategies to degrade different forms of phenols in PPPIE. It also points out the advantages of the latest application of bacteria, fungi and microalgae as microbial consortia in phenols biodegradation. Briefly, phycoremediation of PPPIE consumes carbon dioxide emitted from petro-industries for; valorization of the polluted water to be reused and production of algal biomass which can act as a source of energy for such integrated bioprocess. Besides, the harvested algal biomass can feasibly produce; third-generation biofuels, biorefineries, bioplastics, fish and animal feed, food supplements, natural dyes, antioxidants and many other valuable products. Consequently, this review precisely confirms that the phycoremediation of PPPIE is a win-win process for a green environment and a sustainable future. Thus, to achieve the three pillars of sustainability; social, environmental and economic; it is recommendable to integrate PPPIE treatment with algal cultivation. This integrated process would overcome the problem of greenhouse gas emissions, global warming and climate change, solve the problem of water-scarce, and protect the environment from the harmful negative impacts of PPPIE.     

Production and genetic improvement of a novel antimycotic agent,Saadamycin, against Dermatophytes and other clinical fungi from Endophytic <Emphasis Type="Italic">Streptomyces</Emphasis> sp. Hedaya48

As a part of our ongoing efforts towards finding novel antimycotic agents from marine microflora of the Red Sea, vanillin, 5,7-dimethoxy-4-p-methoxylphenylcoumarin and the new antimycotic compound saadamycin were isolated from endophytic Streptomyces sp. Hedaya48. The producing strain was isolated from the Egyptian sponge Aplysina fistularis and subjected to different UV irradiation doses. A mutant strain Ah22 with 10.5-fold (420 mg/l as compared to 40 mg/l produced by the parental strain) improved saadamycin production was isolated. Production of saadamycin from mutant Ah22 was enhanced to 2.26-fold (950 mg/l) and 2.38-fold (1000 mg/l) under optimized culture conditions in batch culture and bioreactors, respectively. Both saadamycin and 5,7-dimethoxy-4-p-methoxylphenylcoumarin exhibited significant antimycotic activity against dermatophytes and other clinical fungi.