“The occurrence of APase in environmental nucleotide extracts was shown to significantly affect the measured concentrations of cellular nucleotides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate , guanosine triphosphate, uridine triphosphate, and cytidine triphosphate), adenylate energy charge, and guanosine triphosphate/adenosine triphosphate ratios, when conventional methods of nucleotide extraction were employed.”