Functional Studies with Primary Cells Provide a System for Genome-to-Phenome Investigations in Marine Mammals

Abstract

<jats:title>Synopsis</jats:title> <jats:p>Marine mammals exhibit some of the most dramatic physiological adaptations in their clade and offer unparalleled insights into the mechanisms driving convergent evolution on relatively short time scales. Some of these adaptations, such as extreme tolerance to hypoxia and prolonged food deprivation, are uncommon among most terrestrial mammals and challenge established metabolic principles of supply and demand balance. Non-targeted omics studies are starting to uncover the genetic foundations of such adaptations, but tools for testing functional significance in these animals are currently lacking. Cellular modeling with primary cells represents a powerful approach for elucidating the molecular etiology of physiological adaptation, a critical step in accelerating genome-to-phenome studies in organisms in which transgenesis is impossible (e.g., large-bodied, long-lived, fully aquatic, federally protected species). Gene perturbation studies in primary cells can directly evaluate whether specific mutations, gene loss, or duplication confer functional advantages such as hypoxia or stress tolerance in marine mammals. Here, we summarize how genetic and pharmacological manipulation approaches in primary cells have advanced mechanistic investigations in other non-traditional mammalian species, and highlight the need for such investigations in marine mammals. We also provide key considerations for isolating, culturing, and conducting experiments with marine mammal cells under conditions that mimic in vivo states. We propose that primary cell culture is a critical tool for conducting functional mechanistic studies (e.g., gene knockdown, over-expression, or editing) that can provide the missing link between genome- and organismal-level understanding of physiological adaptations in marine mammals.</jats:p>

The initial steps toward the formation of somatic tissue banks and cell cultures derived from captive Antillean manatee (Trichechus manatus manatus) skin biopsies

“…Moreover, development of primary cell cultures represents an interesting tool for elucidating the molecular etiology of physiological modifications, a step in accelerating genome-to-phenome studies (Lam et al, 2020). Despite the notorious importance of somatic tissue banks for species conservation, few studies have been conducted on tissue cryopreservation in marine mammals (Boroda, 2017), and this study is the first step toward the formation of such bank for Antillean manatee tissues.…”

“…Moreover, specifically for marine mammals, these banks can be used for acquiring knowledge regarding the species (Yajing et al, 2018), as well as for studying the influence of fuel and its derivatives (Wise et al, 2014), the impact of chlorine derivatives (Marsili et al, 2014), the toxicity of heavy metals (Wise et al, 2015), and performing immunological and physiological studies (Bogomolni et al, 2016). Moreover, development of primary cell cultures represents an interesting tool for elucidating the molecular etiology of physiological modifications, a step in accelerating genome‐to‐phenome studies (Lam et al, 2020). Despite the notorious importance of somatic tissue banks for species conservation, few studies have been conducted on tissue cryopreservation in marine mammals (Boroda, 2017), and this study is the first step toward the formation of such bank for Antillean manatee tissues.…”

Gene duplications and gene loss in the epidermal differentiation complex during the evolutionary land-to-water transition of cetaceans

“…In conclusion, the EDC has undergone multiple changes during the evolution of cetaceans, indicating that the molecular composition of the epidermis is adapted to aquatic life. The functional characterization of individual epidermal differentiation genes in their normal cellular environment is not possible at present, but may be facilitated by the establishment of in vitro culture and manipulation protocols for keratinocytes of cetaceans in the future 47 .…”

Time Domains of Hypoxia Responses and -Omics Insights

“…These unanswered questions may be best examined in the elephant seal due to its propensity for voluntary breath-holds and the existence of established endocrine, biochemical, and molecular techniques to work with the animals ( Khudyakov et al, 2015 ; Crocker et al, 2016 ). Ongoing investigations using ex vivo systems that are amenable to physiological manipulation and molecular perturbation can also complement in vivo studies while providing insights into mechanisms that confer natural tolerance to hypoxemia and ischemia/reperfusion in diving mammals as described by Allen and Vazquez-Medina (2019) and Lam et al (2020) .…”