Over the last two decades, the use of DNA barcodes has transformed our ability to identify and assess life on our planet. Both strengths and weaknesses of the method have been exemplified through thousands of peer-reviewed scientific articles. Given the novel sequencing approaches, currently capable of generating millions of reads at low cost, we reflect on the questions: What will the future bring for DNA barcoding? Will identification of species using short, standardized fragments of DNA stand the test of time? We present reflected opinions of early career biodiversity researchers in the form of a SWOT analysis and discuss answers to these questions.
This report describes the emergence of a European form of Echinococcus multilocularis that was identified in Canadian wildlife and was associated with human illness.
Preimplantation equine embryos synthesize and secrete fibrinogen, which is a peculiar finding as fibrinogen synthesis almost exclusively occurs in the liver. This study investigated the hypothesis that conceptus-derived fibrinogen mediates cell adhesion during fixation. On day 21 of pregnancy, five integrin subunits, including ITGA5, ITGB1, ITGAV, and ITGB1, displayed significantly higher transcript abundance than on day 16 of pregnancy. Endometrial epithelial cells adhered to fibrinogen in an integrin-dependent manner in an in vitro cell adhesion assay. Bilaminar trophoblast and allantochorion expressed fibrinogen transcript, indicating that fibrinogen expression persists past fixation. Preimplantation-phase endometrium, conceptuses, and microcotyledonary tissue expressed components of the clotting cascade regulating fibrin homeostasis, leaving open the possibility that fibrinogen is converted to fibrin. Fibrinogen is likely to have functions beyond mediating cell adhesion, such trapping growth factors and triggering signaling cascades, and has remarkable parallels to the expression of fibrinogen by some tumors. The deposition of fibrinogen within tumor stroma is characteristic of breast carcinoma, and tumor-derived fibrinogen has been implicated in the metastatic potential of circulating tumor cells. DNA methylation of the fibrinogen locus in equine conceptuses was examined in comparison to liver and endometrium, and across the full gene cluster, was significantly higher for endometrium than liver and conceptus. DNA methylation of regulatory regions did not differ between liver and conceptus, and was significantly lower than in endometrium. These results, therefore, support the hypothesis of DNA methylation being a regulator of fibrinogen expression in the conceptus.
Permafrost-preserved ground squirrel (Urocitellus) burrows in Yukon, Canada contain coprolites (palaeofaeces) that span from the Holocene to at least the Middle Pleistocene (~700 kya). Using shotgun metagenomics and targeted enrichment, we recover a rich, multi-taxon spectrum of ancient environmental DNA from these pellets, including: plants, insects, microbes, and megafauna consistent with eastern Beringian ecosystems. These coprolites consistently preserve an abundance of eukaryotic DNA, enabling the assembly of >18 mitochondrial genomes (ground squirrel, snowshoe hare, steppe bison, horse, and mammoth), and revealing previously unrecognized diversity within Arctic Urocitellus, including a ~700 kya lineage that predates divergence among several extant clades. Characteristic damage patterns, positive/negative controls, and in silico taxon validations strongly support aDNA authenticity, and comparisons with regional permafrost datasets indicate minimal post-depositional leaching. These results show that permafrost coprolites can yield high-resolution records of Quaternary ecosystems and multi-organism population histories, providing a powerful complement to sedimentary and skeletal ancient DNA.