From time to time, we get reminded how widespread thyroid hormones, and related substances are, even in relatively primitive creatures.
Despite the rationale of this paper being to suggest use of some invertebrates to test for thyroid hormone axis disrupting chemicals, I'd also consider that all sorts of chemicals we use might well impact numerous other animals including the ones identified. Knowing that is also important.
Integrated Environmental Assessment and Management
Critical Review
Thyroid-like hormone signalling in invertebrates and its potential role in initial screening of thyroid hormone system disrupting chemicals
J.E. Morthorst, H. Holbech, N. De Crozé, P. Matthiessen, G.A. LeBlanc
First published: 17 May 2022
ABSTRACT
This review examines the presence and evolution of thyroid-like systems in selected aquatic invertebrates with a view to the potential use of these organisms in screens for vertebrate thyroid hormone axis disrupting chemicals (THADCs). Such a screen might assist the phasing-out of some vertebrate testing. Although arthropods including crustaceans do not contain a functional thyroid signalling system, elements of such a system exist in the aquatic phyla molluscs, echinoderms, tunicates and cephalochordates. These phyla are able to synthesise thyroid hormone which has been shown in some groups to induce the nuclear thyroid hormone receptor (THR). Thyroid hormone may act in these phyla through interaction with a membrane integrin receptor. Thyroid hormone regulates inter alia metamorphosis, but unlike in vertebrates, this does not occur via receptor activation by the ligands triiodothyronine (T3) and thyroxine (T4). Instead, the unliganded nuclear receptor itself controls metamorphosis in molluscs, echinoderms and tunicates, while the T3 derivative tri-iodothyroacetic acid (TRIAC) acts as a THR ligand in cephalochordates. In view of this information, it may be possible to develop an invertebrate-based screen that is sensitive to vertebrate THADCs which interfere with thyroid hormone synthesis or metabolism along with interaction with membrane receptors. The review makes some recommendations about appropriate test method development needs.
Full paper is behind a paywall:
setac.onlinelibrary.wiley.c...
Mollusc - A mollusc is an animal such as a snail, clam, or octopus which has a soft body. Many types of mollusc have hard shells to protect them.
Echinoderms are a phylum of marine invertebrates that include starfish, brittle stars, sea cucumbers, sea urchins, sand dollars, and crinoids.
Various species of the subphylum tunicata are commonly known as ascidians, sea squirts, tunicates, sea pork, sea livers, or sea tulips.
Cephalochordata. They are commonly called lancelets.
