Temperature effect on Leishmania enriettii in vitro

Temperature is an important factor in regulating the morphogenesis and growth of hemoflagellates. Leishmania enriettii is limited to growth in the colder parts of the body and does not grow above 37 °C [as cited in de Castro and Pinto. 1960. Journal of Protozoology7, Suppl. abstract 10]. The influence of various temperatures on L. enriettii is examined from the point of view of morphology, activity, growth, respiration, phosphate metabolism, and retention of metabolites. At temperatures above 30 °C, there is a decline in viability in spite of an initially elevated respiratory capacity. Between 35 °C and 37 °C, marked morphological changes occur including flagellar loss and inclusion body formation. These inclusions are lipid in nature. Survival is not significantly impaired for about 20 hours, during which time a division occurs. Acute exposure to elevated temperatures does not impair respiration, nor does it uncouple oxidative phosphorylation as measured by P³² uptake. However, if the organisms are suspended in a simplified medium, inorganic phosphorus accumulates and leaks to the outside. Other substances leak as well. An analysis of these materials utilizing column and thin-layer chromatography and electrophoresis reveals a general loss including guanosine, uracil, hypoxanthine, ribose, and at least thirteen amino acids. Kinetic analysis of the leakage by study of the increase in ultraviolet absorption outside of the cells shows a straight line Arrhenius plot from 10 ° to 40 °C, suggesting that no cataclysmic event (lysis) occurs. The increase in permeability in this range is nearly a thirtyfold change, while respiration increases only twofold. The role of enhanced permeability is discussed as it relates to intracellular parasitism.