Roth Terri L, Philpott Megan, Wojtusik Jessye
Center for Conservation and Research of Endangered Wildlife (CREW), Cincinnati Zoo & Botanical Garden, 3400 Vine Street, Cincinnati, OH 45220 USA.
Conserv Physiol. 2022 Apr 24;10(1):coac025. doi: 10.1093/conphys/coac025. eCollection 2022.
A consequence of the poaching crisis is that managed rhinoceros populations are increasingly important for species conservation. However, black rhinoceroses (BR; ) and Sumatran rhinoceroses (SR; ) in human care often store excessive iron in organ tissues, a condition termed iron overload disorder (IOD). IOD research is impeded by the challenge of accurately monitoring body iron load in living rhinoceroses. The goals of this study were to (i) determine if labile plasma iron (LPI) is an accurate IOD biomarker and (ii) identify factors associated with iron-independent serum oxidative reduction potential (ORP). Serum (106 samples) from SRs ( = 8), BRs ( = 28), white rhinoceros ( = 24) and greater one-horned rhinoceros (GOH; = 16) was analysed for LPI. Samples from all four species tested positive for LPI, and a higher proportion of GOH rhinoceros samples were LPI positive compared with those of the other three species ( < 0.05). In SRs, the only LPI-positive samples were those from individuals clinically ill with IOD, but samples from outwardly healthy individuals of the other three species were LPI positive. Serum ORP was lower in SRs compared with that in the other three species ( < 0.001), and iron chelation only reduced ORP in the GOH species ( < 0.01; ~5%). Serum ORP sex bias was revealed in three species with males exhibiting higher ORP than females ( < 0.001), the exception being the SR in which ORP was low for both sexes. ORP was not associated with age or serum iron concentrations ( ≥ 0.05), but was positively correlated with ferritin ( < 0.01). The disconnect between LPI and IOD was unanticipated, and LPI cannot be recommended as a biomarker of advanced rhino IOD. However, data provide valuable insight into the complex puzzle of rhinoceros IOD.
偷猎危机的一个后果是，人工饲养的犀牛种群对于物种保护变得越来越重要。然而，人工饲养的黑犀牛（BR）和苏门答腊犀牛（SR）的器官组织中常常储存过量的铁，这种情况被称为铁过载紊乱（IOD）。由于难以准确监测活体犀牛的体内铁负荷，IOD的研究受到了阻碍。本研究的目的是：（i）确定不稳定血浆铁（LPI）是否是一种准确的IOD生物标志物；（ii）识别与非铁依赖性血清氧化还原电位（ORP）相关的因素。对8头苏门答腊犀牛、28头黑犀牛、24头白犀牛和16头印度犀（GOH）的血清（共106份样本）进行了LPI分析。所有四个物种的样本LPI检测均呈阳性，与其他三个物种相比，印度犀样本中LPI阳性的比例更高（P<0.05）。在苏门答腊犀牛中，仅有的LPI阳性样本来自临床患有IOD的个体，但其他三个物种外表健康个体的样本LPI也呈阳性。与其他三个物种相比，苏门答腊犀牛的血清ORP较低（P<0.001），并且铁螯合仅降低了印度犀物种的ORP（P<0.01；约5%）。在三个物种中发现了血清ORP的性别偏差，雄性的ORP高于雌性（P<0.001），苏门答腊犀牛是例外，该物种两性的ORP均较低。ORP与年龄或血清铁浓度无关（P≥0.05），但与铁蛋白呈正相关（P<0.01）。LPI与IOD之间的脱节出乎意料，因此不建议将LPI作为晚期犀牛IOD的生物标志物。然而，这些数据为犀牛IOD的复杂谜题提供了有价值的见解。
