Biomedical subjects

S E Ramadan

Publications and source records attributed to S E Ramadan.

6 recordsLinked to original sources

PubMed1990

Metabolism of selenium in a selenium-dependent bacterium.

A selenium-dependent Bacillus sp. is able to grow well up to 3% sodium selenite-containing media. The bacterium completely failed to grow on media devoid of selenium. The presence of selenium in the growth media increased the bacterial contents of proteins, carbohydrates, and lipids. The highest quantities of amino acids were detected at 2% sodium selenite-containing media. The bacterium metabolized selenite into several protein selenoamino acids such as selenomethionine and selenocysteine/selenocystine, as well as nonprotein selenoamino acids, such as selenocystathionine. Several phosphoamino acids were detected in the presence of elevated levels of selenium. The synthesized protein seems not to be affected by the presence of selenium.

Amino Acids↗

PubMed1990

Mobilization of selenium by a selenium-dependent bacterium.

A selenium-dependent bacterium, Bacillus sp., failed to grow on selenium-free media. However, it is able to grow at high concentrations of sodium selenite containing media up to 3% (w/v). It accumulated extraordinary high quantities of selenium, 432 ppm/mL. The bacterium generated the transformation of inorganic selenium into volatile selenium form(s) into the atmosphere. The biological release of volatile selenium basically depended on several factors: incubation temperature, pH, incubation periods, and substrate concentration. Maximal quantity of the volatile selenium form was obtained at 30 degrees C, pH 7, and 1% (w/v) sodium selenite.

Bacillus↗

PubMed1989

Incorporation of tellurium into amino acids and proteins in a tellurium-tolerant fungi.

Aspergillus fumigatus, Aspergillus terreus, and Penicillium chrysogenum, a tellurium tolerant fungi, are able to grow on sulfur free medium amended with 0.2% (w/v) tellurite. Tellurium was incorporated into several types of low and high molecular weight proteins. The newly detected telluro-proteins contained an extraordinary high level of tellurium, as well as telluro-cysteine, telluro-cystine, telluro-methionine, and serine.

Amino Acids↗

PubMed1988

Selenium metabolism in a strain of Fusarium.

Fusarium sp. was isolated from Sinai soil at Egypt. It showed tendency to tolerate high concentrations of selenium in the form of sodium selenite up to 3.5% (w/v). The microscopic examination revealed some morphological distortions. However, the fungus was capable to circumvent the toxic effect of selenium. The fungus possess strong reducing ability as high quantities of elemental selenium were precipitated within the fungal cells as well as on the surface of the fungal hyphae and spores. The presence of selenium increased the cellular contents of carbohydrates, proteins, and lipids. Labeling studies indicate the incorporation of selenite into certain amino acids: selenocysteine and selenocysteic acid. Moreover, the presence of selenium induced the biosynthesis of several types of low molecular weight proteins. The results demonstrated different modes of detoxification of selenium toxicity.

Fusarium↗

PubMed1988

Selenoprotein in Aspergillus terreus.

Aspergillus terreus, a moderately selenium-tolerant fungus, metabolized Se-selenite into several protein seleno-amino acids: selenomethionine and selenocysteine, as well as, nonprotein seleno-amino acids, selenocystathionine, and y-glutamyl selenomethyl selenocysteine. The results indicate the failure of the fungus to discriminate between sulphur and selenium. Selenium was also incorporated into several proteins of different molecular weights, mostly of low molecular weight proteins. Labeled studies showed the presence of high levels of selenomethionine and selenocysteine in the protein hydrolysate. The actual incorporation of protein seleno-amino acids into the fungal protein was proven. The results demonstrated a finding that detracts from previous held views.

Aspergillus↗

PubMed1988

Influence of cadmium on certain biological activities in a cadmium-tolerant fungi.

Aspergillus carbonarius and a strain of Penicillium are able to grow on Harrold's agar media amended with different concentrations of cadmium chloride up to 2.5% (w/v). Considerable quantities of cadmium were absorbed by both fungi. A. carbonarius absorbed more cadmium than the Penicillium sp. did, under the same culturing conditions. In the presence of cadmium, the determined cellular contents of proteins, lipids, and carbohydrates were extraordinary high, whereas the activities of certain enzymes, lipases, amylases, and proteases were inhibited. The fungal rate of growth and sporulations were mostly suppressed. Conidiations were inhibited at lowest concentrations. At 1% Cd Cl2, A. carbonarius produced malformed conidiophores, whereas the Penicillium sp. was less affected. At higher concentrations conidiophores production were entirely suppressed and several hyphal swellings were produced.

Aspergillus↗