Xenopus tropicalis oocytes as an advantageous model system for the study of intracellular Ca(2+) signalling.
1. The purpose of this study was to compare oocytes from the pipid frogs Xenopus tropicalis and Xenopus laevis, with respect to their utility for studying Ca(2+) signalling mechanisms and for expression of heterologous proteins. 2. We show that X. tropicalis oocytes possess an intracellular Ca(2+) store that is mobilized by inositol (1,4,5) trisphosphate (IP(3)). Ca(2+) signalling is activated by endogenous lysophosphatidic acid receptors and cytosolic Ca(2+) activates a plasma membrane chloride conductance. The spatiotemporal organization of cytosolic Ca(2+) signals, from the microscopic architecture of elementary Ca(2+) 'puffs' to the macroscopic patterns of Ca(2+) spiking are closely similar to the local and global patterns of Ca(2+) release previously characterized in oocytes from X. laevis. 3. By injecting X. tropicalis oocytes with cDNA encoding an ER-targeted fluorescent protein construct, we demonstrate the capacity of the X. tropicalis oocyte to readily express heterologous proteins. The organization of ER is polarized across the oocyte, with the IP(3)-releaseable store targeted within an approximately 8 microm wide band that circumscribes the cell. 4. We conclude that the X. tropicalis oocyte shares many of the characteristics that have made oocytes of X. laevis a favoured system for studying Ca(2+) signalling mechanisms. Moreover, X. tropicalis oocytes display further practical advantages in terms of imaging depth, Ca(2+) signal magnitude and electrical properties. These further enhance the appeal of X. tropicalis as an experimental system, in addition to its greater amenability to transgenic approaches.
Marchant
J S
JS
Laboratory for Cellular and Molecular Neurobiology, Department of Neurobiology & Behavior, University of California at Irvine, 92697-4550, USA.
Parker
I
I
D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D004594:Electrophysiology; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005260:Female; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D008164:Luminescent Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism; D008564:Membrane Potentials / Q000502:physiology; D008845:Microinjections; D018613:Microscopy, Confocal; D023421:Models, Animal; D009865:Oocytes / Q000378:metabolism*; D014981:Xenopus
D008164:Luminescent Proteins; D015544:Inositol 1,4,5-Trisphosphate; D002118:Calcium