Depolarizationof the axon hillock to threshold results in the generationand propagation of an action potential. The action poten-tial is a transient change in the membrane potential charac-terized by a gradual depolarization to threshold, a rapid ris-ing phase, an overshoot, and a repolarization phase.
Ecology. Staphylococcus aureus is a normal inhabitant of the skin and mucous membranes in the nose of a healthy human, while S. epidermidis inhabits only the skin of healthy humans. S. aureus is infectious to both animals and humans.he Staphylococcus aureus genome, which is the most common species amoung the genome projects, is about 2.8 Mega-base pairs long with approximately 2,600 open reading frames, comprising 84.5% of the genome.
Staphylococcus aureus is a gram-positive coccal bacterium that is a member of the Firmicutes, and is frequently found in the respiratory tract and on the skin forms where perspiration is present. It is often positive for catalase and nitrate reduction.Although S. aureus is not always pathogenic, it is a common cause of skin infections such as abscesses, respiratory infections such as sinusitis, and food poisoning.Pathogenic strains often promote infections by producing potent protein toxins, and expressing cell-surface proteins that bind and inactivate antibodies.lthough S. aureus is not always pathogenic, it is a common cause of skin infections such as abscesses, respiratory infections such as sinusitis, and food poisoning.