New Zealand Journal of Zoology abstracts
A simplified protocol for detecting two systemic bait markers (Rhodamine
B and iophenoxic acid) in small mammals
D. C. Purdey
University of Waikato
Private Bag 3105
Hamilton, New Zealand
Present address: Department of Conservation, Regional Office, P.O.
Box 112, Hamilton.
M. Petcu
Bioengineering Technology,
Hortresearch
Private Bag 3123
Hamilton, New Zealand
C. M. King
University of Waikato
Private Bag 3105
Hamilton, New Zealand
Abstract We developed a method of quantifying levels
of fluorescence in the whiskers of wild stoats (Mustela erminea) using
fluorescence microscopy and Axiovision 3.0.6.1 software. The method allows
for discrimination between natural fluorescence present in or on a whisker,
and the fluorescence resulting from the ingestion of the systemic marker
Rhodamine B (RB), although some visual judgement is still required. We also
developed a new high performance liquid chromatography (HPLC) protocol for
detecting the systemic marker iophenoxic acid (IPA) in the blood of laboratory
rats (Rattus norvegicus) and wild stoats. With this method, the blood
of an animal that has consumed IPA can be tested for the presence of the
foreign IPA compound itself. This is a more reliable test than the previous
method, which measured the raised level of natural blood protein-bound iodine
correlated with IPA absorption. The quantity of blood required from animal
subjects is very small (10 μl), so the testing is less intrusive and the
method can be extended to smaller species. The extraction technique uses
methanol, rather than acids and heavy metal salts, thereby simplifying the
procedure. Recovery of IPA is quantitative, giving a highly reliable reading.
In experiments on captive rats the IPA method proved successful. Of 12 positively
marked carcasses, two that had not been frozen for the 24 h before blood
samples were taken showed relatively lower IPA levels. The same IPA detection
method, as well as the whisker analysis for RB, was applied successfully
to a population of wild stoats to which both Rhodamine B and IPA were made
available at bait stations. The presence of both bait markers was detectable
in rats for at least 21 days and in stoats for at least 27 days.
Keywords stoat; Mustela erminea; rat; Rattus
norvegicus; bait markers; systemic markers; iophenoxic acid; Rhodamine
B; high performance liquid chromatography (HPLC)
Z02034 Received 11 December 2002; accepted 8 April 2003; Online publication
date 8 September 2003
New Zealand Journal of Zoology, 2003, Vol. 30: 175-184
0301-4223/03/3003-0175 $7.00/0 © The Royal Society of New Zealand
2003
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