Leishmania donovani amastigotes mobilize organic and inorganic osmolytes during regulatory volume decrease. 2005

Ann Lefurgey, and Melissa Gannon, and Joseph Blum, and Peter Ingram
Durham Veterans Affairs Medical Center, Duke University Medical Center, Durham, NC 27705, USA. a.lefurgey@cellbio.duke.edu

The protozoan parasite Leishmania donovani encounters large fluctuations in osmolality as it cycles between its insect vector and human host. The flagellated promastigote exhibits regulatory volume responses involving organic and inorganic osmolytes, but little is known about volume regulation in the clinically relevant amastigote that multiplies within the parasitophorous vacuoles of mammalian host cells. Using a combination of morphological, X-ray microanalytical, and biochemical approaches we determined that non-motile amastigotes respond to hypotonic stress with (1) an amino acid and l-alanine-mediated regulatory volume decrease, and (2) a parallel release of Na+, K+, P (presumably as negatively charged phosphates), and subsequently Cl- from cytoplasm and the cell as a whole. In addition P, Zn2+, and subsequently Ca2+ increase in acidocalcisomes as Cl- content declines in this compartment. This evidence is the first to document subcellular translocation of, and thus a potential role for, zinc in volume regulatory responses. These coordinated changes in organic and inorganic osmolytes demonstrate that amastigote subcellular compartments, particularly acidocalcisomes, function in maintaining ionic homeostasis in the response of Leishmania amastigotes to hypo-osmotic stress.

UI MeSH Term Description Entries
D007893 Leishmania donovani A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals and causes visceral leishmaniasis (LEISHMANIASIS, VISCERAL). The sandfly genera Phlebotomus and Lutzomyia are the vectors. Leishmania (Leishmania) donovani,Leishmania leishmania donovani,Leishmania donovanus,Leishmania leishmania donovanus,donovani, Leishmania leishmania,donovanus, Leishmania,donovanus, Leishmania leishmania,leishmania donovanus, Leishmania
D010758 Phosphorus A non-metal element that has the atomic symbol P, atomic number 15, and atomic weight 31. It is an essential element that takes part in a broad variety of biochemical reactions. Black Phosphorus,Phosphorus-31,Red Phosphorus,White Phosphorus,Yellow Phosphorus,Phosphorus 31,Phosphorus, Black,Phosphorus, Red,Phosphorus, White,Phosphorus, Yellow
D011188 Potassium An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.
D002118 Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002713 Chlorine An element with atomic symbol Cl, atomic number 17, and atomic weight 35, and member of the halogen family. Chlorine Gas,Chlorine-35,Cl2 Gas,Chlorine 35,Gas, Chlorine,Gas, Cl2
D003594 Cytoplasmic Granules Condensed areas of cellular material that may be bounded by a membrane. Cytoplasmic Granule,Granule, Cytoplasmic,Granules, Cytoplasmic
D000222 Adaptation, Physiological The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT. Adaptation, Physiologic,Adaptations, Physiologic,Adaptations, Physiological,Adaptive Plasticity,Phenotypic Plasticity,Physiological Adaptation,Physiologic Adaptation,Physiologic Adaptations,Physiological Adaptations,Plasticity, Adaptive,Plasticity, Phenotypic
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D012964 Sodium A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23. Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23
D014882 Water-Electrolyte Balance The balance of fluid in the BODY FLUID COMPARTMENTS; total BODY WATER; BLOOD VOLUME; EXTRACELLULAR SPACE; INTRACELLULAR SPACE, maintained by processes in the body that regulate the intake and excretion of WATER and ELECTROLYTES, particularly SODIUM and POTASSIUM. Fluid Balance,Electrolyte Balance,Balance, Electrolyte,Balance, Fluid,Balance, Water-Electrolyte,Water Electrolyte Balance

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