Identification of Saiga Horns Used in Traditional Chinese Medicines using DNA Barcoding Technology

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Article by Zhigang Jiang, Institute of Zoology, Chinese Academy of Sciences & Endangered Species Scientific Commission of the People's Republic of China. Contact: jiangzg@ioz.ac.cn

AnimalFeatures

Article published in Saiga News Issue 20 on page 26.

The saiga population in Northern Zinjiang, China, was extirpated in the 1960s due to over-hunting. Saiga horns, called "Lingyangjiao" in Chinese, have long been used in Traditional Chinese Medicines (TCM). The horns of domestic sheep (Ovis aries), goat (Capra hircus), goitered gazelle (Gazella subgutturosa), Tibetan antelope (Pantholops hodgsonii), Tibetan gazelle (Procapra picticaudata), Mongolian gazelle (P. gutturosa) and Przewalski's gazelle (P. przewalskii) are also sold as substitutes for "Lingyangjiao" in TCM markets. These substitutes are all of similar morphology, especially when they are sold in slices, cubes or powders, making discrimination between these products with the naked eye rather difficult in TCM markets, especially when the merchants sell fake saiga horn on purpose.

This lack of order in the "Lingyangjiao" market impedes not only control of the trade in saiga horns but also conservation of other endangered ungulates. Therefore, an effective and convenient method to identify "Lingyangjiao" is needed.

Methods like morphological identification, micro-structure comparison, thin layer chromotography (TLC), and gel electrophoresis have been used to discriminate horns of saiga antelope from other species or artificial counterfeits. With the advantages of accuracy, simplicity, and the potential to deal with highly degraded samples, genetic markers are widely applied in wildlife identification nowadays.

NJ Tree Of COI Sequences

Figure. Neighbour-Joining (NJ) tree of COI sequences of 644 bp from eight species involved in TCM "Lingyangjiao" markets. Samples of horns were marked with their species names. The sequences with GenBank accession numbers were retrieved from GenBank.

In a paper published in Ecology and Evolution in 2015, Dr Jing Chen and colleagues from the Wildlife and Behavioural Ecology Research Group of the Institute of Zoology, Chinese Academy of Sciences, used Chytochrome C oxidase subunit 1 (COI) as a molecular marker, in order to establish a method to distinguish between the horns of sheep and goat, goitered gazelle, Tibetan antelope, Tibetan gazelle, Mongolian gazelle, saigas and Przewalski's gazelle. As species diagnosis is a basic requirement for monitoring wildlife trade and enforcing wildlife laws, this barcoding diagnostic method is expected to contribute to monitoring trade in "Lingyangjiao" and to support the conservation of these endangered antelope species.

The cells in horns are surrounded by keratinized tissues, which are inherently difficult to digest. The genomic DNA of "Lingyangjiao" from TCM markets was generally degraded, particularly when the horns were processed into slices, cubes or powder before sale and stored at room temperature and high humidity for a long period. Dr. Chen et al.'s protocol covered procedures including extraction of genomic DNA from horn samples, PCR amplification and analysis of barcoding data sets. A nested-PCR system was designed to deal with degraded samples, which are the only available materials in forensic cases. For the two powdered horn samples with low genomic DNA concentrations, two rounds of nested-PCR were performed.

Nowadays, the legal supply of saiga horns to TCM in China relies on horns obtained before the CITES trade ban; horns from legal sources are being depleted over time. In order to pursue high profits, occasionally saiga horns are smuggled by traffickers. Saiga horns are similar to the horns of other gazelles in morphology; some merchants substitute inferior horns as good horns, fakes as genuine horns, thus cheating the consumers. This new method provides an effective forensic technique to curb saiga horn smuggling and to monitor saiga horns in the TCM market.

Alternatively, you can access the full article published in the journal - Ecology and Evolution here.