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By comparing the isotopic composition of tissues deposited at different times, we can identify individuals that shift diets over time and individuals with constant diets. We define an individual as an isotopic specialist if tissues deposited at different times have similar isotopic composition. If tissues deposited at different times differ in isotopic(More)
Understanding rates of isotopic incorporation and discrimination factors between tissues and diet is an important focus of ecologists seeking to use stable isotopes to track temporal changes in diet. We used a diet-shift experiment to measure differences among tissues in (13)C incorporation rates in house sparrows (Passer domesticus). We predicted faster(More)
OBJECTIVE To determine whether cows with evidence of previous infection with Neospora caninum were less likely to abort or give birth prematurely during an outbreak of neosporosis, compared with herdmates with evidence of primary infection. DESIGN Cohort study. ANIMALS 208 pregnant beef cows. PROCEDURES Aborted fetuses and calves born prematurely were(More)
Neospora caninum infection is a common cause of bovine abortion. One method by which cattle can acquire infection is through ingestion of oocysts; however, this has not yet been proved to cause transplacental infection or abortion. In this study, 19 cows, pregnant between 70 and 176 days, were administered 1500 to 115,000 oocysts through an esophageal tube.(More)
We previously reported that Neospora caninum can be induced to express BAGI, a bradyzoite antigen, within 3 days of culture under stress conditions. The main goals of the present experiment were to increase the expression of BAGI in vitro (in part by extending cultures for 9 days), to observe parasitophorous vacuoles at various points of stage(More)
Serum samples from 70 (33 aborting and 37 non-aborting) dairy cows from a herd in California were analyzed for Neospora caninum antibodies in different laboratories by various serologic assays including enzyme-linked immunosorbent assay (ELISA) with recombinant antigens (Nc4.1 and Nc14.1), kinetic ELISA, whole tachyzoite lysate ELISA, immunostimulating(More)
Ecologists conduct isotopic incorporation experiments to determine the residence time of various stable isotopes in animal tissues. These experiments permit determining the time window through which isotopic ecologists perceive the course of diet changes, and therefore the scale of the inferences that we can make from isotopic data. Until recently, the(More)
Identification of a definitive host for Neospora caninum has been inhibited by lack of an efficient method for producing bradyzoites, needed for oral infectivity trials. An improved protocol for producing bradyzoite-containing tissue cysts in mouse brains is described. Six variables, including mouse strain (Balb/C, CBA/Ca, and ICR), sex, N. caninum isolate(More)
Polar bears (Ursus maritimus) summer on the sea ice or, where it melts, on shore. Although the physiology of "ice" bears in summer is unknown, "shore" bears purportedly minimize energy losses by entering a hibernation-like state when deprived of food. Such a strategy could partially compensate for the loss of on-ice foraging opportunities caused by climate(More)