Molecular markers in keratins from Mysticeti whales for species identification of baleen in museum and archaeological collections

Abstract

Baleen has been harvested by indigenous people for thousands of years, as well as collected by whalers as an additional product of commercial whaling in modern times. Baleen refers to the food-filtering system of Mysticeti whales; a full baleen rack consists of dozens of plates of a tough and flexible keratinous material that terminate in bristles. Due to its properties, baleen was a valuable raw material used in a wide range of artefacts, from implements to clothing. Baleen is not widely used today, however, analyses of this biomolecular tissue have the potential to contribute to conservation efforts, studies of genetic diversity and a better understanding of the exploitation and use of Mysticeti whales in past and recent times. Fortunately, baleen is present in abundance in museum natural history collections. However, it is often difficult or impossible to make a species identification of manufactured or old baleen. Here, we propose a new tool for biomolecular identification of baleen based on its main structural component alpha-keratin (the same protein that makes up hair and fingernails). With the exception of minke whales, alpha-keratin sequences are not yet known for baleen whales. We therefore used peptide mass fingerprinting to determine peptidic profiles in well documented baleen and evaluated the possibility of using this technique to differentiate species in baleen samples that are not adequately identified or are unidentified. We examined baleen from ten different species of whales and determined molecular markers for each species, including species-specific markers. In the case of the Bryde’s whales, differences between specimens suggest distinct species or sub-species, consistent with the complex phylogeny of the species. Finally, the methodology was applied to 29 fragments of baleen excavated from archaeological sites in Labrador, Canada (representing 1500 years of whale use by prehistoric people), demonstrating a dominance of bowhead whale (Balaena mysticetus) in the archaeological assemblage and the successful application of the peptide mass fingerprinting technique to identify the species of whale in unidentified and partially degraded samples.

Identification of rhinoceros keratin using direct analysis in real time time‐of‐flight mass spectrometry and multivariate statistical analysis

“…Accordingly, our approach suggests that keratin source can be readily distinguished among four mammalian families (rhinocerotids, bovids, equids, and manids). These results are in line with previous studies suggesting that chemical profiles of keratin differ among taxonomic groups . In this regard, we acknowledge that only two of our sample groups include individuals representing all extant species: rhinocerotids and manids.…”

“…These results are in line with previous studies suggesting that chemical profiles of keratin differ among taxonomic groups. 17,18 In this regard, we acknowledge Interestingly, while all four taxonomic groups in our study classified separately, the general keratin chemotypes of rhinoceros horn, bovid horn, and domestic horse hoof were similar (Figure 1).…”

“…Recently, several studies have used mass spectrometry for taxonomic identification of keratin. For example, peptide mass fingerprinting has been shown to distinguish common mammal keratins at the genus level, and this same method has been used for species identification of keratinous baleen in whales . Chemical odor profiles of African rhinoceros species appear to differ based on gas chromatography and time‐of‐flight mass spectrometry .…”

“…For example, peptide mass fingerprinting has been shown to distinguish common mammal keratins at the genus level, 17 and this same method has been used for species identification of keratinous baleen in whales. 18 Chemical odor profiles of African rhinoceros species appear to differ based on gas chromatography and time-of-flight mass spectrometry. 19 Taken together, mass spectrometry appears to be a promising tool that could be useful for forensic identification of keratinous items.…”

Mercury and stable isotope cycles in baleen plates are consistent with year-round feeding in two bowhead whale (Balaena mysticetus) populations

“…Given the rate of change now occurring in Arctic seas, and especially in the nearshore habitats important to migratory species like bowhead whales, it seems all the more urgent to develop time series taking advantage of media like baleen, which have the potential to produce records of foraging and reproduction for individuals for periods spanning as much as 25 years (e.g., Hunt et al 2014;Solazzo et al 2017). Although complex, these records have the potential to reveal changes in food webs and consequent changes in whale foraging.…”