153Gadolinium as a useful radiolanthanide for long-term labeling of tissues in Japanese quail

153Gadolinium (153Gd), with gamma energies of 97 keV (30%) and 103 keV (20%), and a nuclear-life of 242 days and with no primary charged particles, was selected as the radiolanthanide for labeling proteins and tissues in Japanese quail. Ranges of dose-responses 18 hr after giving Gd (153Gd labeled) were: males, livers 24.4% for .00015 mumol/100 g to 63.8% for .15 mumol/100 g; laying females, livers 6.5% for .00015 mumol/100 g to 72.7% for 15 mumol/100 g and growing oocytes 83.2% for .00015 mumol/100 g to 6.4% for 15 mumol/100 g. Accumulation of .015 mumol/100 g doses of 153Gd in tissues common to both sexes were greater in males than in females at 1, 6, and 18 hr. The exception was the pancreas, where for all three sampling times the percentages for females were twice those for males. Comparison of 153Gd with 140lanthanum (140La) showed 18-hr levels of 27%/g liver in males and 1.6%/g liver and 11.8%/g growing oocyte in females for both nuclides. Double-labeling with 153Gd and 144cerium (144Ce) showed that a near-toxic dose of La (15 mumol/100 g) caused a marked decrease in labeling of growing oocytes (e.g., largest oocyte, La-treated females, Gd 14.6%, Ce 6.1%; controls Gd 42.2%, Ce 35.5%) and a marked increase in labeling of livers (La-treated, Gd 51.2%, Ce 43.3%; controls; Gd 7.62%, Ce 4.75%).