Abstract:
Species identification following shark-related incidents is critical for effective incident management and for collecting data to inform shark-bite mitigation strategies. Witness statements are not always reliable, and species identification is often ambiguous or missing. Alternative methods for species identification include morphological assessments of bite marks, analysis of collected teeth at the scene of the incident, and genetic approaches. However, access to appropriate collection media and robust genetic assays have limited the use of genetic technologies. Here, we present a case study that facilitated a unique opportunity to compare the effectiveness of medical gauze readily available in first-aid kits, and forensic-grade swabs in collecting genetic material for shark-species identification. Sterile medical gauze and forensic-grade swabs were used to collect transfer DNA from the bite margins on a bitten surf ski which were compared to a piece of shark tissue embedded along the bite margin. Witness accounts and the characteristics of the bite mark impressions inferred the involvement of a Carcharodon carcharias (white shark). The morphology of a tooth found on the boat that picked up the surf ski, however, suggested it belonged to an Orectolobus spp. (wobbegong). Genetic analysis of DNA transferred from the shark to the surf ski included the application of a broad-target nested PCR assay followed by Sanger sequencing, with white shark contribution to the \'total sample DNA\' determined with a species-specific qPCR assay. The results of the genetic analyses were congruent between sampling methods with respect to species identification and the level of activity inferred by the donor-specific DNA contribution. These data also supported the inferences drawn from the bite mark morphology. DNA from the recovered tooth was PCR amplified with a wobbegong-specific primer pair designed for this study to corroborate the tooth\'s morphological identification. Following the confirmation of gauze used for sampling in the case study event, two additional isolated incidents occurred and were sampled in situ using gauze, as typically found in a first-aid kit, by external personnel. DNA extracted from these gauze samples resulted in the identification of a white shark as the donor of the DNA collected from the bite marks in both instances. This study, involving three incidents separated by time and location, represents the seminal application of gauze as a sampling media after critical human-shark interactions and strongly supports the practical implementation of these methods in the field.
摘要:
与鲨鱼有关的事件发生后的物种识别对于有效的事件管理和收集数据以告知鲨鱼咬伤缓解策略至关重要。证人陈述并不总是可靠的,物种识别往往是模糊或缺失的。物种鉴定的替代方法包括咬痕的形态评估,分析事发现场采集的牙齿,和遗传方法。然而,获得适当的收集介质和强大的遗传测定限制了遗传技术的使用。这里,我们提出了一个案例研究,促进了一个独特的机会,以比较医疗纱布的有效性随时可用的急救包,和法医级拭子收集遗传物质用于鲨鱼物种鉴定。使用无菌医用纱布和法医级拭子从被咬伤的冲浪滑雪板的咬伤边缘收集转移DNA,并将其与沿咬伤边缘嵌入的鲨鱼组织进行比较。证人的说法和咬痕印象的特征推断出Carcharodoncarcharharas(白鲨)的参与。在拿起冲浪滑雪板的船上发现的牙齿的形态,然而,暗示它属于一个坏蛋。(wobbegong)。从鲨鱼转移到冲浪滑雪的DNA的遗传分析包括应用广泛的目标巢式PCR测定,然后进行Sanger测序,白鲨对物种特异性qPCR测定的“总样本DNA”的贡献。在物种鉴定方面的采样方法与由供体特异性DNA贡献推断的活性水平之间,遗传分析的结果是一致的。这些数据也支持从咬痕形态得出的推论。使用本研究设计的wobbeggong特异性引物对PCR扩增了回收牙齿的DNA,以证实牙齿的形态鉴定。在案例研究事件中用于取样的纱布确认后,另外发生了两起孤立事件,并使用纱布在现场取样,通常在急救箱中发现,外部人员。从这些纱布样品中提取的DNA导致在两种情况下将白鲨鉴定为从咬痕中收集的DNA的供体。这项研究,涉及三个按时间和地点分开的事件,代表了纱布在关键的人与鲨鱼相互作用后作为采样介质的开创性应用,并强烈支持这些方法在该领域的实际实施。