L-glutamine is an essential amino acid, which serves as a major energy source for cells in culture. L-glutamine is added for optimal cell performance in a culture medium ( Ghyslaine Vanier,(2007),Characterization of the invasion of porcine endothelial cells by Streptococcus suis serotype 2,Canadian Journal Of Camparative Medicine,71(2),pages: 81-89).The utilization of glutamine under carbon starvation conditions by cultured Saccharomyces cerevisiae and its relation to the cytoplasmic compartmentation of the transcriptional activator Gln3 has been studied.The use of glutamine in cultured rat islets to probe a-ketoisocaproate oxidation has been investigated.