Biology subjects

Dyck, M.

Publications and source records attributed to Dyck, M..

3 recordsLinked to original sources

bioRxiv2025

Changes in sea ice alter genetic structure of an iconic Arctic apex predator in less than three decades

Climate change is having profound effects on biodiversity and species distributions worldwide. Nowhere are these effects potentially more pronounced than in the Arctic, where warming is almost two times the global average, and where year-round sea ice extent has significantly decreased, affecting many ice-dependent species. The polar bear (Ursus maritimus) is a circumpolar, apex Arctic predator, a sentinel of climate change, and a symbol of conservation. It is of immense cultural and spiritual importance to Inuit peoples and is hunted across the Arctic. Declines in sea ice have caused habitat fragmentation and loss, disrupting movement and prey access, potentially altering genetic structure and influencing polar bears potential to persist. Using samples collected from 1997 to 2020 by Inuit across much of the Canadian Arctic, 322 genome-wide autosomal DNA markers specifically designed to quantify polar bear genetic structure and a very stringent spatial-temporal method, we compare polar bear spatial genetic structure and landscape features between two periods across a consistent distribution:1997-2008 and 2009-2020. We observe marked changes in spatial genetic structure across the Arctic Archipelago over just two decades, shifting the boundaries between polar bear genetic clusters by [~]250 km. Landscape resistance models reveal the importance of sea ice and land cover type for each period, with spatial lag models showing that genetic change is best predicted by sea ice shifts between periods. Our study reveals rapid changes in genetic structure of polar bears in the Canadian Arctic, helps to inform conservation and management, and offers insight on future polar bear persistence across its immense, remote distribution.

genomics↗

bioRxiv2023

A new multiplexed magnetic-capture - droplet digital PCR (ddPCR) tool for monitoring wildlife population health and pathogen surveillance

Anthropogenic stressors are exacerbating the emergence and spread of pathogens worldwide. In regions like the Arctic where ecosystems are particularly susceptible, marked changes are predicted in regional diversity, intensity, and patterns of infectious diseases. To understand such rapidly changing host-pathogen dynamics and mitigate the impacts of novel pathogens, we need sensitive disease surveillance tools. We developed and validated a novel multiplexed, magnetic-capture and ddPCR tool for the surveillance of multiple pathogens in polar bears, a sentinel species that is considered susceptible to climate change and other stressors with a pan-Arctic distribution. Through sequence-specific magnetic capture, we concentrated five target template sequences from three zoonotic bacteria (Erysipelothrix rhusiopathiae, Francisella tularensis, and Mycobacterium tuberculosis complex) and two parasitic (Toxoplasma gondii and Trichinella spp.) pathogens from large quantities (< 100 g) of host tissue. We then designed and validated two multiplexed probe-based ddPCR assays for the amplification and detection of the low concentration target DNA. Validations used 48 polar bear tissues (muscle and liver). We detected 14, 1, 3, 4, and 22 tissue positives for E. rhusiopathiae, F. tularensis, Mycobacterium tuberculosis complex, T. gondii, and Trichinella spp., respectively. These multiplexed assays offer a rapid, specific tool for quantifying and monitoring the changing geographical and host distributions of pathogens relevant to human and animal health.

molecular biology↗

bioRxiv2019

Postnatal development of skeletal muscle in IUGR pigs: morphofunctional phenotype and molecular mechanisms

Intrauterine growth restriction (IUGR) is a serious condition which impairs the achievement of the fetus full growth potential and occurs in a natural and severe manner in pigs. Knowledge on skeletal muscle morphofunctional phenotype and its molecular regulation in IUGR pigs is important to understand postnatal muscle development and may help the establishment of therapies to improve skeletal muscle growth in those individuals. To investigate the impairment of skeletal muscle postnatal development due to IUGR, we evaluated the histomorphometrical pattern of the semitendinosus muscle, the Myosin Heavy Chain (embryonic, I, IIa, IIb and IIx MyHC) fiber composition and the relative expression of genes related to myogenesis, adipogenesis and growth during three specific periods: postnatal myogenesis (newborn to 100 days of age), postnatal development (newborn to 150 days of age), and hypertrophy (100 days to 150 days of age), comparing IUGR and normal birth weight (NW) pigs. Growth restriction in utero affected muscle fiber diameter, total fiber number and muscle cross sectional area which were smaller in IUGR pigs at birth (P < 0.05). Even though the percentage of MyHC-I myofibers was higher in IUGR females at birth (P < 0.05), in older gilts, a lower percentage of MyHC-IIx isoform (P < 0.05) and the presence of emb-MyHC were also observed in that experimental group. Regarding the pattern of gene expression in the postnatal myogenesis period, growth restriction in utero led to a down regulation of myogenic factors, which delayed the expression of signals that induces skeletal muscle myogenesis (PAX7, MYOD, MYOG, MYF5 and DES). Taken together, the muscle morphofunctional aspects described and their ontogenetic regulation define the possible molecular origins of the notorious damage to the postnatal musculature development in IUGR pigs.

cell biology↗