title: Regulation of calcium transport in the early life stages of an ancient fish, Acipenser fulvescens.
abstract: The freshwater, cartilaginous lake sturgeon (Acipenser fulvescens) encounters its greatest calcium (Ca(2+)) demand in the early life stages. In this study we examined Ca(2+) regulation of lake sturgeon larvae reared at three levels of environmental [Ca(2+)]-0.1, 0.2, and 1.5 mmol L(-1)-from hatch until after the transition to exogenous feeding. Examination of skin, gill, and yolk sac with scanning electron microscopy (SEM) indicated that the density and surface area of mitochondria-rich cells (MRCs) varies over developmental time but that availability of environmental Ca(2+) affected only MRC density. SEM results also demonstrated that Ca(2+) transport is adjusted in localization over the course of development, with the transition to primarily branchial uptake occurring earlier in the highest environmental [Ca(2+)]. Net whole-animal Ca(2+) flux was primarily dependent on influx rate. The increase in whole-body Ca(2+) uptake following the transition to exogenous feeding was greatest in larval lake sturgeon acclimated to low environmental [Ca(2+)], and it suggests that intestinal absorption may supplement enhanced branchial uptake in Ca(2+)-limited fish.
authors.affiliation: Department of Biology, University of West Georgia, Carrollton, Georgia 30118; 2Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada.
authors.forename: Janet
authors.initials: J
authors.lastname: Genz
authors.forename: Lauren
authors.initials: L
authors.lastname: Shute
authors.forename: W Gary
authors.initials: WG
authors.lastname: Anderson
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D004777:Environment; D005260:Female; D005399:Fishes / Q000254:growth & development / Q000378:metabolism*; D005880:Gills / Q000378:metabolism* / Q000648:ultrastructure; D007408:Intestinal Absorption; D017136:Ion Transport; D008297:Male; D008855:Microscopy, Electron, Scanning; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D002118:Calcium