AUTHOR=Dönmez Eda Merve , Siebert Ursula , Fabrizius Andrej 

TITLE=Diving on damage—the muscle transcriptome of parasitic infested harbor porpoises (Phocoena phocoena) hints at oxidative stress but not hypoxia

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1232305

DOI=10.3389/fmars.2023.1232305

ISSN=2296-7745

ABSTRACT=The only native cetacean in German waters, the harbor porpoise (Phocoena phocoena), is impacted by numerous pathological lesions in the respiratory tract mainly caused by parasites or bacteria. While harbor porpoises have been observed to not use their complete lung volume, it has not been studied if this insufficiency leads to lower oxygen uptake, impaired diving ability and ultimately reduced foraging success. This project aims to analyze whether harbor porpoises developed novel molecular adaptations to compensate impairments in oxygen supply, thus remaining viable and competitive despite the high parasitic load. Here, initial comparative transcriptome RNA sequencing (NextSeq 2000, Illumina) was performed on muscles of harbor porpoises with a respiratory tract considered as healthy and of harbor porpoises that suffered from more severe lesions and parasitic infestations in the respiratory tract. Our findings suggest hint at an elevated response to oxidative stress in the muscles of parasitic infested harbor porpoises compared to healthy animals. Higher antioxidant and antiapoptotic gene expression in the muscles of non-healthy harbor porpoises might function as a compensatory effect to enhanced ROS production and accumulation in the muscles. Simultaneously enhanced selective proteasomal degradation and myogenesis suggests a tightly controlled, finely tuned switch of the intrinsic muscle response to stress. Lipid metabolism pathways and rate-limiting transcripts involved in anaerobic glycolysis metabolism were upregulated and may uphold muscle energy supply for tissue function and energy-consuming regenerative and biosynthetic processes. These preliminary results hint at a defined response of the muscle to oxidative stress that may be caused by lung tissue with more severe pathological lesions and may indicate a possible adaptation in cetaceans.