Sectoring of fungal colonies induced by low concentrations of fernasan

An inhibitor of Aspergillus flavus has been isolated from peanuts and identified as 5,7-dimethoxyisoflavone. Authentic 5,7-dimethoxyisoflavone, synthesized from benzyl-2-hydroxy-4,6 dimethoxyphenyl (3), and the isolated compound display identical ultraviolet spectra in methanol, in methanol+sodium methoxide, and in methanol+AlCl₃; similar behavior in solvent extraction, column chromatography, TLC, and fungal inhibition.     

Isolation of aflatoxin from Acacia and the incidence of Aspergillus flavus in the Sudan

A series of environmental and clinical isolates of Sporothrix schenckii being studied in our laboratories under standard conditions of temperature, humidity and media, displayed, in some of the isolates, large dematiaceous hyphae. The large hyphae could be seen to produce the fine hyphae associated with S. schenckii on which typical microconidia developed. Typical microconidia also developed occasionally on the large hyphae, and strands of the unusually large hyphae also were seen to form arthroconidia. Some strains formed large, thin-walled cells on thin and/or thick hyphae resembling the balloon cells seen in mature colonies of Trichophyton tonsurans.All strains which have demonstrated these various and unusual structures histopathologically produced typical sporotrichosis in laboratory animals. When reisolated from these animals, the cultures again exhibited the unusual structures, as well as those typical of S. schenckii.     

Cloning, nucleotide sequence determination and expression of the genes encoding cytochrome P-450soy and ferredoxinsoy (soyB) from Streptomyces griseus

Xenobiotic transformation by Streptomyces griseus (ATCC13273) is catalysed by a cytochrome P-450, designated cytochrome P-450soy. A DNA segment carrying the structural gene encoding P-450soy (soyC) was cloned using an oligonucleotide probe constructed from the protein sequence of a tryptic peptide. Following DNA sequencing the deduced amino acid sequence of P-450soy was compared with that for P-450cam, revealing conservation of important structural components including the haem pocket. Expression of the cloned soyC gene product was demonstrated in Streptomyces lividans by reduced CO:difference spectral analysis and Western blotting. Downstream of soyC, a gene encoding a putative [3Fe-4S] ferredoxin (soyB), named ferredoxinsoy, was identified.     

SALT REGULATION AND LEAF SENESCENCE IN AGING LEAVES OF JAUMEA CARNOSA (LESS.) GRAY (ASTERACEAE), A SALT MARSH SPECIES EXPOSED TO NaCl STRESS

The effects of increasing salt stress on leaf senescence and salt regulation were investigated in the halophyte Jaumea carnosa in hydroponic culture experiments. The plants were grown in Hoagland's nutrient solution plus additional NaCl salt (0, 300, 400, 500 mm NaCl). Decreases in nucleic acids, protein, and chlorophyll were used as indicators of leaf senescence. The results indicated no definitive pattern of acceleration in leaf senescence with increasing salt stress. Salt regulation was also unaffected as leaves aged under increasing NaCl concentrations. The results are consistent with those of previous studies of the halophyte which indicated that the species was very tolerant of high NaCl concentrations.     

Effect of Herbicides on the Toxicity of Fungicides Against Rhizoctonia solani Causing Damping-off of Cotton

The effect of two herbicides (paraquat and simazine on the antifungal activity of two fungicides (captan and mounsrin) against Rhizoctonia solani was studied. when the herbicides paraquat and simazine were applied to soil they altered the effectiveness of both fungicides in controlling R. solani , thus causing damping-off of cotton. Both herbicides increased the toxicity of both fungicides against mycelial growth of the fungus. In pot tests, seeds or soil treated with captan or mounsrin, gave better control of R. solani damping-off disease when the soil was treated with paraquat or simazine compared to untreated soil. Captan was, however, found to be more effective in controlling the disease than mounsrin.     

Protein prenylation in eukaryotic microorganisms: genetics, biology and biochemistry

Modrfication of proteins at C-terminal cysteine residue(s) by the isoprenoids farnesyl (C15) and geranylgeranyl (C20) is essential for the biological function of a number of eukaryotic proteins including fungal mating factors and the small, GTP-binding proteins of the Ras superfamily. Three distinct enzymes, conserved between yeast and mammals, have been identified that prenylate proteins: farnesyl protein transferase, geranylgeranyl protein transferase type I and geranylgeranyl protein transferase type II. Each prenyl protein transferase has its own protein substrate specificity. Much has been learned about the biology, genetics and biochemistry of protein prenylation and prenyl protein transferases through studies of eukaryotic microorganisms, particularly Saccharo-myces cerevisiae. The functional Importance of protein prenylation was first demonstrated with fungal mating factors. The initial genetic analysis of prenyl protein transferases was in S. cerewisiae with the isolation and subsequent characterization of mutations in the RAM1, RAM2, CDC43 and BET2 genes, each of which encodes a prenyl protein transferase subunit. We review here these and other studies on protein prenylation in eukaryotic microbes and how they relate to and have contributed to our knowledge about protein prenylation in all eukaryotic cells.     

Chaetomella acutiseta produces chaetomellic acids A and B which are reversible inhibitors of farnesyl-protien transferase

Chaetomellic acids A and B, isolated from Chaetomella acutiseta, are specific inhibitors of farnesyl-protein transferase that do not inhibit geranylgeranyl transferase type 1 or squalene synthase. Chaetomellic acids A and B are reversible inhibitors, resemble farnesyl diphosphate and probably inhibit FPTase by substituting for farnesyl diphosphate. Chaetomellic acid production appears to be widespread within the genus Chaetomella. Correspondence to: R. B. Lingham     

Oxamniquine for treating Schistosoma mansoni infection in Sudan.

The efficacy and acceptability of oral oxamniquine were assessed in Sudanese patients infected with Schistosoma mansoni. Cure rates, determined by the absence of viable eggs in the stools six months after treatment, were 94.9% in patients treated with a total of 60 mg/kg, 78.8% in patients treated with 40 mg/kg, and 68.9% in patients treated with 30 mg/kg. All treatment regimens considerably reduced the egg count in those patients not cured. The drug was well tolerated and the side effects were minimal and transient, the most common being dizziness. Most of the patients noticed a reddish discoloration of their urine, which was probably caused by a metabolite of the drug. In patients who received 60 mg/kg oxamniquine there were transient rises in eosinophil counts and in serum alanine aminotransferase concentrations. Though 60 mg/kg was by far the most effective dose in terms of cure rate, egg counts were significantly reduced on all three doses. The lower doses could therefore be useful in a low-cost control programme in reducing transmission of S mansoni infection.