A PRELIMINARY STUDY OF EPIGENETIC ESTIMATION OF AGE OF THE ANTARCTIC MINKE WHALE <i>BALAENOPTERA BONAERENSIS</i>

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  • A PRELIMINARY STUDY OF EPIGENETIC ESTIMATION OF AGE OF THE ANTARCTIC MINKE WHALE BALAENOPTERA BONAERENSIS

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Abstract

<p>Age is one of the most important life history parameters for assessment and management of marine living resources. Counting of the growth layers deposited in the earplugs is the most accepted technique for determining chronological age of baleen whales. However unreadable growth layers form in the earplugs of some individual whales. In such cases, alternative methods of age estimation are required. The objective of the present study was to examine the utility of the DNA methylation technique as a proxy to estimate chronological age in the Antarctic minke whale. For this purpose, skin tissues of a total of 100 Antarctic minke whales sampled in the Pacific region of the Antarctic by JARPAII surveys were used. Earplug-based age data from the same whales were used for calibration purposes. Seven CpG sites in three genes (TET2, CDKN2A and GRIA2) were selected for the analysis. In a previous study, these sites showed significant correspondence between methylation levels and age in humpback whales. Methylation levels of the seven CpG sites were scored successfully. Four CpG sites showed significant regressions with age, which contrasted with the case of the humpback whale where all seven sites showed significant regressions with age. The assay predicted age from skin samples with a standard deviation of 8.865 years. This low precision makes the age estimated by the CpG methylation technique unsuitable for use in population dynamics models such as the statistical catch-at-age (SCAA). Furthermore CpGs methylation levels fluctuated among body positions of the whale, particularly between dorsal (exposure to sunlight) and ventral sides. The precision of the CpG methylation technique for age estimation could be improved by increasing the number of CpG sites showing a good correlation with age, and this work is ongoing. In addition, other factors including variation of CpG methylation levels between different tissues should be examined to further evaluate the utility of the DNA methylation techniques as a proxy of age estimation in baleen whales.</p>

Journal

  • Cetacean Population Studies

    Cetacean Population Studies 2 (1), 5-14, 2020-06-30

    Publication Committee for Cetacean Population Studies

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