Elephant sharks possess uncommon appears and evolutionary historical past, the latter of which makes them an attention-grabbing animal mannequin for evaluating divergent improvement paths with people. Credit score: Michael Baker, UC San Diego Well being Sciences
Elephant sharks provide a novel perspective on how people developed; a brand new examine parses some beforehand unexplained reproductive variations.
Researchers at College of California San Diego Faculty of Medication and in Japan have used an historical fish to reel in new insights about human biology and, particularly, how and why a broadly used remedy works to abort pregnancies (in individuals, not fish).
The findings revealed within the February 11, 2022, on-line challenge of ACS Pharmacology & Translational Science.
The elephant shark (Callorhinchus milii) is an uncommon wanting and unusual animal mannequin. Recognized by a number of names, akin to ghost shark, elephant fish and silver trumpeter, the species is present in waters off southern Australia. The graceful-skinned, cartilaginous fish grows to a most dimension of 4 ft and poses no menace to people. Their distinctive hoe-shaped, proboscis-like snout is used to detect prey, primarily shellfish and bottom-dwelling invertebrates, by way of motion and weak electrical fields.
Nevertheless it’s a unique attribute that makes elephant sharks appropriate for sure sorts of analysis: They belong to the oldest group of jawed vertebrates and have the slowest evolving genome of all identified vertebrates, which make them best for investigating how some organic methods have developed in bony vertebrates, together with people. The most recent examine, evaluating progesterone receptor (PR) activation in elephant sharks and people, offers insights in how steroid activation developed within the latter, and why it really works the best way it does in the present day.
Progesterone is a hormone that, in girls, regulates the menstrual cycle, preparation for conception and sustaining a being pregnant. The consequences of progesterone are mediated by its nuclear receptor, PR. Researchers discovered that PR activation in elephant sharks requires a unique mixture of hormones and steroids than PR activation in people, with the latter requiring fewer however extra particular hormonal and steroidal triggers.
Extra apparently, they found that RU486, a medically authorized medical compound that blocks or terminates being pregnant in people and is often referred to as “the abortion tablet,” doesn't have the identical impact in elephant sharks. It doesn't inhibit progesterone activation of elephant shark PR.
The findings, mentioned senior creator Michael Baker, PhD, analysis professor at UC San Diego Faculty of Medication, illuminate the divergent evolutionary paths of fish and people, and provide perception about how different extra well-liked animal fashions, particularly zebrafish, is perhaps problematic when trying to parse the pathology of endocrine disruption (when pure or artifical chemical compounds mimic or intervene with hormones that regulate improvement, replica and different primary features) or develop new medicine.
Reference: “Regulation by Progestins, Corticosteroids, and RU486 of Transcriptional Activation of Elephant Shark and Human Progesterone Receptors: An Evolutionary Perspective” by Xiaozhi Lin, Wataru Takagi, Susumu Hyodo, Shigeho Ijiri, Yoshinao Katsu and Michael E. Baker, 6 December 2021, ACS Pharmacology & Translational Science.
DOI: 10.1021/acsptsci.1c00191
Co-authors embrace: Xiaozhi Lin, Shigeho Ijiri and Yoshinao Katsu, Hokkaido College, Japan; and Wataru Takagi and Susumu Hyodo, College of Tokyo
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