Whales are among the longest lived mammals, and thus of interest to researchers investigating the comparative biology of aging. There is the hope that examining the biochemistry of mammals with exceptional longevity may point the way to therapies that can slow human aging. The odds of this being the case are unknown at present: too little progress has been made to assess whether or not the differences between species will be useful as a basis for the near term development of treatments to be applied to older adults. A more realistic expectation is that these differences in biochemistry could help to prioritize work on rejuvenation therapies by pointing out which portions of cellular metabolism are more important to aging.
One important question in aging research is how differences in genomics and transcriptomics determine the maximum lifespan in various species. Despite recent progress, much is still unclear on the topic, partly due to the lack of samples in non-model organisms and due to challenges in direct comparisons of transcriptomes from different species. The novel ranking-based method that we employ here is used to analyze gene expression in the gray whale and compare its de novo assembled transcriptome with that of other long- and short-lived mammals.
Gray whales are among the top 1% longest-lived mammals. Despite the extreme environment, or maybe due to a remarkable adaptation to its habitat (intermittent hypoxia, Arctic water, and high pressure), gray whales reach at least the age of 77 years. In this work, we show that long-lived mammals share common gene expression patterns between themselves, including high expression of DNA maintenance and repair, ubiquitination, apoptosis, and immune responses. Additionally, the level of expression for gray whale orthologs of pro- and anti-longevity genes found in model organisms is in support of their alleged role and direction in lifespan determination.
Remarkably, among highly expressed pro-longevity genes many are stress-related, reflecting an adaptation to extreme environmental conditions. The conducted analysis suggests that the gray whale potentially possesses high resistance to cancer and stress, at least in part ensuring its longevity.