Karsten Amanda H, Turner John W
Medical College of Ohio, Department of Physiology and Molecular Medicine, Toledo, Ohio 43614-5804, USA.
J Exp Zool A Comp Exp Biol. 2003 Oct 1;299(2):188-96. doi: 10.1002/jez.a.10300.
The present study examined the feasibility of measuring the steroid hormone corticosterone in fecal extracts of epaulette sharks, Hemiscyllium ocellatum. Six immature, captive-raised epaulette sharks (four females and two males) were obtained from two different zoos and were maintained in a closed-system, 530-liter aquarium. After a one-month adaptation, fecal samples were collected daily from each animal for 33 days. Five-day sets of samples were pooled within animals to insure sufficient material for analysis. Fecal hormone extraction was achieved using repeated cycles of dichloromethane and aqueous washes. The levels of corticosterone were measured by reverse-phase high-performance liquid chromatography (HPLC). Corticosterone presence in HPLC eluent peaks from fecal extracts was determined by comparison of the elution pattern of corticosterone standard with the elution patterns of fecal extracts with and without the addition of tritiated corticosterone or exogenous, unlabeled corticosterone. Exclusive presence of corticosterone in HPLC eluent peaks presumed to be corticosterone was determined by nuclear magnetic resonance mass spectrometry. Corticosterone levels, calculated from a 10-point standard curve, ranged from 1.2 to 20.9 ng/g feces across all sharks, with 92.3% of values being < or =13.5 ng/g. Within individuals, the lowest average for corticosterone levels across 33 days was 2.6+/-0.4 ng/g feces, and the highest average was 8.4+/-2.2 ng/g feces. This study demonstrated that corticosterone was extractable from and reliably measurable in fecal extracts of epaulette sharks. This is the first evidence of this hormone in epaulette sharks and the first report of fecal corticosterone in elasmobranchs.
本研究考察了测定肩章鲨（Hemiscyllium ocellatum）粪便提取物中类固醇激素皮质酮的可行性。从两家不同的动物园获取了6条人工饲养的未成年肩章鲨（4条雌性和2条雄性），并将它们饲养在一个530升的封闭系统水族箱中。经过一个月的适应期后，连续33天每天从每只动物采集粪便样本。将动物体内5天的样本集合在一起，以确保有足够的材料进行分析。粪便激素提取通过二氯甲烷和水洗的重复循环来实现。皮质酮水平通过反相高效液相色谱法（HPLC）测定。通过比较皮质酮标准品的洗脱模式与添加和未添加氚化皮质酮或外源性未标记皮质酮的粪便提取物的洗脱模式，确定粪便提取物的HPLC洗脱峰中是否存在皮质酮。通过核磁共振质谱法确定假定为皮质酮的HPLC洗脱峰中是否仅存在皮质酮。根据10点标准曲线计算，所有鲨鱼粪便中皮质酮水平在1.2至20.9纳克/克之间，92.3%的值≤13.5纳克/克。在个体内部，33天内皮质酮水平的最低平均水平为2.6±0.4纳克/克粪便，最高平均水平为8.4±2.2纳克/克粪便。本研究表明，皮质酮可从肩章鲨的粪便提取物中提取并可靠测定。这是该激素在肩章鲨中的首次证据，也是板鳃亚纲动物粪便皮质酮的首次报道。
