FEMS Microbiology Letters 82 (1991) 341-344 © 1991 Federation of European Microbiological Societies 0378-1097/91/$03.50 Published by Elsevier ADONIS 037810979100399H 341 FEMSLE 04596 Amino acid uptake as a function of differentiation in Candida albicans: studies of a non-germinative variant Simminder Kaur and Prashant Mishra School of Life Sciences, Jawaharlal Nehru University, New Delhi, India Received 14 May 1991 Revision received 11 June 1991 Accepted 12 June 1991 Key words: Candida albicans: Non-germinative variant; pH-directed morphogenesis; Amino acid uptake 1. SUMMARY 2. INTRODUCTION The transport of four amino acids (L- methionine, L-phenylalanine, L-lysine and L- alanine) was studied during pH-regulated dimor- phism in Candida albicans and its stable, non- germinative variant. The permeases responsible for uptake responded differently to differentia- tion and the transport activities varied during the course of morphogenesis. An increase in uptake around the time of evagination was observed in all four amino acids in both the strains studied. The uptake rates of L-methionine and L-phenyl- alanine were greater in fully differentiated hy- phae, while the rate of L-lysine was higher in fully differentiated buds. Uptake rates of L-alanine, however, did not show any morphotypic related variation. The possible implication of these trans- port activities in relation to differentiation is dis- cussed. Correspondence to: P. Mishra, School of Life Sciences, Jawa- harlal Nehru University, New Delhi-110 067, India. Candida albicans is an opportunistic dimorphic pathogen which evades the host defense system under immunocompromised conditions and causes mild- to life-threatening disease [1]. Among various attributes, changes in its colonial [2-5] and cellular morphology [1,6] are important for its success in the host environment. While the colony morphology is known to switch sponta- neously [2-4], cellular morphology is affected by many factors [6-15]. Amongst these, nutritional factors have been, especially, studied in detail and N-acetyl D-glucosamine [9,10], glucose [11,12] and amino acids [7,8,11,13-15] have emerged as the main factors which mediate its morphological transition. The importance of individual amino acids in inducing morphological transition has been de- scribed [11,15], however, much remains to be understood in terms of their uptake and its rela- tionship to yeast-mycelial transition. Although comparative studies with morphological variants offer great potential to enhance the present un- derstanding of the differential expression of the