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With Plate 13) SUMMARY Culture studies and field observations on Peltigera praetextata (Flk.) Vain, provide evidence of the existence of a delicate state of balance betw een the co-symbionts of this lichen.Excessive supply of nutrients to discs of the lichen results in the outgrowth of the phycobiont and consequent destruction of the symbiotic relationship.The conjoint effect of excessive moisture and light is shown to bring about similar symbiotic breakdown.It is suggested that these three factors acting together as a growth-regulating system are chiefly responsible for the success of the lichen symbiosis.

Nil Nil Nil Nil Nil Nil 34-32(871-4) Ngomakurira ins. (mm.) Nil 2-78 (70-6) 11-89(302 0) 21-47(545-3) 9-44(239-8) 2-79(70-8) Nil Nil Nil Nil Nil Nil 48-37 (1,228-5) 14-05 (357-1) Acarospora schleicheri, Dermatiscum thunbergii and Caloplaca ctrmabarina, can be seen

The effect of a beta glucan synthase inhibitor, cilofungin, amphotericin B and 5-fluorocytosine on opsonization, phagocytosis and intracellular killing of Candida albicans blastospores by glass-adherent human neutrophils was determined by microscopy and dye exclusion staining. Pretreatment of blastospores for 2, 4, 6 and 18 h with 1.25 mg/l cilofungin resulted in 24-28% of neutrophils ingesting compared to 24% with no drug present. There was no significant difference in the phagocytic index with increased incubation time. Percentage ingestion and phagocytic index values were not significantly different when blastospores were pretreated for 2 h in the presence of 3, 7, 15, 31 and 62 mg/l cilofungin. Comparable concentrations of amphotericin B and 5-fluorocytosine gave similar results. In the absence of cilofungin, intracellular killing after 2 h was 54%. In the presence of 1 and 10 mg/l cilofungin, 85-90% of intracellular blastospores were killed. Therapeutic levels of amphotericin B or 5-fluorocytosine did not enhance intracellular killing. These data demonstrate the potentiation of intracellular killing of Candida albicans by neutrophils in the presence of cilofungin.

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