Preservation of collagen in the soft tissues of frozen mammoths.

We investigated the characteristics of extracellular matrix (ECM) in the soft tissue of two frozen baby woolly mammoths (Mammuthus primigenius) that died and were buried in Siberian permafrost approximately 40,000 years ago. Morphological and biochemical analyses of mammoth lung and liver demonstrated that those soft tissues were preserved at the gross anatomical and histological levels. The ultrastructure of ECM components, namely a fibrillar structure with a collagen-characteristic pattern of cross-striation, was clearly visible with transmission and scanning electron microscopy. Type I and type IV collagens were detected by immunohistochemical observation. Quantitative amino acid analysis of liver and lung tissues of the baby mammoths indicated that collagenous protein is selectively preserved in these tissues as a main protein. Type I and type III collagens were detected as major components by means of liquid chromatography-mass spectrometry analysis after digestion with trypsin. These results indicate that the triple helical collagen molecule, which is resistant to proteinase digestion, has been preserved in the soft tissues of these frozen mammoths for 40,000 years.

Semi-Nondestructive Certification of Crocodilian Leather by LC-MS Detection of Collagen Marker Peptides.

Leather produced from crocodile, alligator, and caiman skin is widely used in the fashion industry. Crocodilian leather is generally more expensive than mammalian leather, and the value greatly differs even between the crocodilian species. However, inappropriate labeling of the animal source on leather products sometimes arises from accidental or fraudulent substitution, which is difficult to unambiguously detect by existing methods. In the present study, animal source identification of crocodilian leather was carried out using type I collagen-derived marker peptides generated after dechroming, heat denaturation, and trypsin digestion. Definitive discrimination between the three crocodilian species and also a related species, lizard, was achieved based on the detection patterns of selected six marker peptides, determined by LC-MS. Furthermore, powdering of the leather samples enabled a reduction in the sample amount required and allowed the elimination of the dechroming step. Approximately 100 µg of powder was taken from commercial leather watch straps by filing, resulting in only slight damage to the undersides of the straps. The animal sources of the crocodilian products and also a crocodile-embossed calf product were successfully identified using a combination of the crocodilian marker peptides and previously established mammalian marker peptides. This semi-nondestructive species identification method is not only useful for certification of leather products but also for monitoring of international trade of leather and skin.

A Rapid and Simple LC-MS Method Using Collagen Marker Peptides for Identification of the Animal Source of Leather.

Identification of the animal source of leather is difficult using traditional methods, including microscopic observation and PCR. In the present study, a LC-MS method was developed for detecting interspecies differences in the amino acid sequence of type I collagen, which is a major component of leather, among six animals (cattle, horse, pig, sheep, goat, and deer). After a dechroming procedure and trypsin digestion, six tryptic peptides of type I collagen were monitored by LC-MS in multiple reaction monitoring mode for the animal source identification using the patterns of the presence or absence of the marker peptides. We analyzed commercial leathers from various production areas using this method, and found some leathers in which the commercial label disagreed with the identified animal source. Our method enabled rapid and simple leather certification and could be applied to other animals whether or not their collagen sequences are available in public databases.