L-Glutamine: an amino acid required for maintenance of the tegumental membrane potential of Schistosoma mansoni

Abstract

SUMMARYThe tegumental membrane potential (–63±2·9 mV) of adult male Schistosoma mansoni in RPMI-1640 is significantly depolarized (–26±7·3 mV) when the parasite is incubated in inorganic media (Hank's Balanced Saline or RPMI-1640 without organic constituents). Of 9 amino acids (L-glutamine, D-glutamine, L-arginine, L-proline, L-aspartate, L-glutamate, L-asparagine, L-isoleucine and L-methionine) L-glutamine alone is sufficient to repolarize the membrane potential to a value (–56±4·5 mV) not significantly different from that found in RPMI-1640. Repolarization by glutamine is dose-dependent, with significant effects obtained as low as 0·10 mM. The concentration of phosphate in the medium also significantly alters the membrane potential. Physiological levels of phosphate (5·6 mM) are necessary in conjunction with L-glutamine to obtain the full repolarization of the membrane potential. In the absence of organic constituents, the membrane potential is strongly dependent on the external medium pH. When L-glutamine is present in the medium, the membrane potential becomes virtually independent of the external pH.

Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology

“…mansoni worms, living in the vertebrate bloodstream, are continuously exposed to molecular oxygen (O 2 ), which is known to be physiologically utilized by the parasites to sustain egg production [ 43 , 44 ] and energy demand through the oxidative phosphorylation (OXPHOS) [ 42 , 45 , 46 – 55 ]. Regarding the nutrient requirements, it is known that carbohydrates [ 55 ], and particularly glutamine metabolism, play a key role to maintain parasite energy homeostasis, motility, tegumental resting membrane potential, muscle tension and viability in adult worms [ 56 – 59 ]. Although adult S .…”

In vitro culture of Neoechinorhynchus buttnerae (Acanthocephala: Neoechinorhynchidae): Influence of temperature and culture media

“…A longer lifespan was observed in the RPMI 1640 medium treatment under the three temperatures tested than that of the other media treatments, which might be associated with the presence of L-glutamine, an essential amino acid. Based on a study by Lane et al (1987), L-glutamine has the capacity to maintain the normal polarization of the parasite cuticle because it is a neutral amino acid in physiological conditions. Its transport does not affect the potential of the membrane unless it is linked to and alters the internal load.…”

“…Its transport does not affect the potential of the membrane unless it is linked to and alters the internal load. The presence of L-glutamine was the main factor causing S. mansoni resistance to pH alterations once the membrane pH was strongly related to the external pH (LANE et al, 1987).…”

“…For each mole of lactate produced by anaerobic metabolism, 2 moles of protons are generated (HOCHACHKA & MOMMSEN, 1983). From this, the glutamine cycle allows the parasite to regulate the intracellular pH to minimize the proton excess (LANE et al, 1987). Moreover, L-glutamine is important for supplying nitrogen to NAD, NADPH, and nucleotides serving as sources of secondary energy for metabolism (LANE et al, 1987).…”

Basic Techniques and Limitations in Establishing Cell Culture: a Mini Review

“…Out of many amino acids available, glutamine is most commonly used as additive in cell culture and it serves as a secondary energy and carbon source for metabolism (Lane and Bennett, 1987;Newsholme et al, 2003). But L-glutamine is only stable for about 3 weeks at 4 0 C in cell culture medium and converts to a form that cannot be used by cells.…”