IUCN / SSC Cat Specialist Group - Digital Cat Library |
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| Jewgenow, K.; Naidenko, S.V.; G”ritz, F.; Vargas, A.; Dehnhard, M. | |
| Monitoring testicular activity of male Eurasian (_Lynx lynx_) and Iberian (_Lynx pardinus_) lynx by fecal testosterone metabolite measurement | |
| 2006 General and Comparative Endocrinology (149): 151-158 | |
The aim of the present study was to identify relevant fecal testosterone metabolites in the Eurasian lynx (_Lynx lynx_) using HPLC analysis and to evaluate the speciWcity of two testosterone immunoassays against these fecal metabolites. Finally, fecal hormone analysis was used to characterize seasonal reproductive activity of captive male Eurasian and Iberian (_Lynx pardinus_) lynx. Fecal samples from a male Eurasian lynx who received an i.v. injection of [3H]testosterone were subjected to HPLC analysis. All HPLC fractions were analyzed for radioactivity and androgen content by two testosterone immune assays (EIA and Testosterone-Immulite© kits, DPC Biermann, Germany). Furthermore, fecal samples from four Eurasian lynx males (nD174) and three Iberian lynx (nD52) were collected throughout the year and fecal testosterone metabolites were determined with Testosterone-Immulite© assay. HPLC separation of radiolabeled Eurasian lynx fecal extract indicated that the majority of testosterone metabolites are substances with a higher polarity than testosterone. Only minor proportion of radioactivity co-eluted with authentic testosterone and dihydrotestosterone. Enzymatic hydrolysis and solvolysis of the fecal extract were insuYcient to liberate testosterone. After solvolysis relatively more activity was eluated the position of DHT, but the majority of metabolites remained unaVected. The EIA measured substantial amount of immunoreactivity, which corresponded with two radioactive peaks. Additionally, both immunoassays recognized two metabolites, which were only minor components according to their radioactivity. The Immulite assay was able to recognize a metabolite at the position of dihydrotestosterone. HPLC separation of Iberian lynx feces extracts revealed a similar metabolite pattern determined by EIA that were typical for Eurasian lynx fecal extracts. Simultaneous analyses of fecal samples with both testosterone assays provided comparative results for both lynx species (Eurasian lynx, r2D0.488; p <0.001; Iberian lynx, r2D0.85, p < 0.0001). Thus, seasonal reproductive activity of male Eurasian lynx was demonstrated also by Immulite©-assay, conWrming high testosterone levels during breeding season in March/April as previously documented with EIA. Preliminary results on testosterone measurements in Iberian lynx feces conWrmed the suitability of the applied Immulite© test in this highly endangered species. |
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