Selection for carotenogenesis in the yeast Phaffia rhodozyma by dark-generated singlet oxygen

Article Abstract:

The heterobasidiomycetous yeast Phaffia rhodozyma produces astaxanthin, a carotenoid pigment that functions as an antioxidant. Exposure of wild-type and astaxanthin mutant strains to hypochlorous acid (HOCl) or hydrogen peroxide (H2O2) resulted in low astaxanthin levels, indicating that HOCl and H2O2 were strongly selective for carotenogenesis. Exposure of cells to 1,4-diazabicylco[2.2.2]-octane restored astaxanthin levels. Since 1,4-diazabicylco[2.2.2]-octane is a known quencher of singlet oxygen, it was concluded that selection for carotenogenesis in P. rhodozyma involves generation of singlet oxygen.

Carotenoid metabolism

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Properties and use of botulinum toxin and other microbial neurotoxins in medicine

Article Abstract:

The medical applications of botulinum toxin type A is evaluated. The toxin is used for treating hyperactive muscle diseases such as hemifacial spasms, strabismus and blepharopras spasm. The theurapeutic action stems from its structure which has binding sites highly specific for myoneural junctions. This condition prevents the release of acetylcholine and results in flaccid paralysis. The preparation, properties and physiological effects of botulinum injection are described. Other neurotoxins with similar actions were described, including tetanus toxins, tetrodoxins and saxitoxins.

Health aspects, Botulinum toxin, Botulinum toxins, Neurotoxic agents

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Growth polarity transitions in a dimorphic fission yeast

Article Abstract:

A study was conducted to demonstrate that the yeast-to-mycelium transition was a gradual process related to a reversal from bipolar growth to unipolar growth involving transition to symmetric division, inhibition of cell separation, cytoskeleton reorganization and development of vacuoles at the non-growing pole. The organism that was perceived to be capable of showing this transition was the Schizosaccharomyces japonicus japonicus. Results revealed that the strain developed bipolarly growing, symmetrically dividing fission yeast provided that the cAMP levels were high.

Cells (Biology), Growth, Cells, Polarity (Biology), Molds (Fungi)

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