Re: Essential Iodine Displacement Deficiency Syndrome

HELL YEAH! You GO, Matt! I had no idea that you had a blog, I'm going to have to explore around a bit and get illuminated:) Thanks for popping by, you always raise the bar around these parts.

Yes.. halogen imbalance affects all beings...And we can certainly consider the bees as our canaries, can't we? here's a bit I dug up on Iodine metabolism in insects...


http://tinyurl.com/2j3qc9


Iodine metabolism and thyroid-related functions in organisms lacking thyroid follicles: are thyroid hormones also vitamins?

JG Eales
Department of Zoology, University of Manitoba, Winnipeg, Canada.

Thyroid-related functions in organisms devoid of follicular thyroid tissue have been reviewed. In the lamprey, a primitive vertebrate, the larva concentrates Iodide and synthesizes thyroid hormones (TH) by iodoperoxidase (IP)-mediated iodination of a thyroglobulin (TG)-like molecule in a subpharyngeal afollicular endostyle. The endostyle is the thyroid homolog, and it reorganizes into a follicular thyroid at metamorphosis to the adult. Ascidians and amphloxus, invertebrate protochordate relatives of vertebrates, also concentrate Iodide and synthesize TH in a subpharyngeal afollicular endostyle, but the endostyle never transforms to follicles. Ascidian plasma contains L- thyroxine and its more biologically active derivative 3,5,3'-triiodo-L- thyronine, and TH receptors exist, but TH effects are poorly understood. No other invertebrates possess an endostyle. Several invertebrates concentrate Iodide at other sites and form protein- incorporated iodohistidines and iodotyrosines; however, de novo iodothyronine biosynthesis through IP-mediated TG iodination has not been established. Nevertheless, TH occur in invertebrates, and exogenous iodothyrosines or iodothyronines have effects on jellyfish, insects, and sea urchins. Furthermore, gut bacteria metabolize TH, and plants may synthesize TH by nonenzymatic oxidative iodination. Thus, TH occur in many organisms and, after ingestion and enteric absorption, can enter the food chain. Indeed, sea urchin larvae obtain TH required to induce metamorphosis from plant diatoms. Thyroid hormones can therefore have vitamin-like effects and, in conjunction with vitamin D, and possibly with other steroids, may be more aptly termed vitamones. Availability of exogenous TH has implications for models of invertebrate and vertebrate TH metabolism and Iodine salvaging, and it may explain the prominent and probable ancestral role of peripheral mechanisms in regulating thyroidal status.

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http://tinyurl.com/2lvv5d


Comparing thyroid and insect hormone signaling

Transitions between different states of development, physiology, and life history are typically mediated by hormones. In insects, metamorphosis and reproductive maturation are regulated by an interaction between the sesquiterpenoid juvenile hormone (JH) and the steroid 20-hydroxy-ecdysone (20E). In vertebrates and some marine invertebrates, the lipophilic thyroid hormones (THs) affect metamorphosis and other life history transitions. Interestingly, when applied to insects, THs can physiologically mimic many facets of JH action, suggesting that the molecular actions of THs and JH/20E might be similar. Here we discuss functional parallels between TH and JH/20E signaling in insects, with a particular focus on the fruit fly, Drosophila melanogaster, a genetically and physiologically tractable model system. Comparing the effects of THs with the well defined physiological roles of insect hormones such as JH and 20E in Drosophila might provide important insights into hormone function and the evolution of endocrine signaling.

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http://tinyurl.com/2k2vyf



Do thyroid hormones function in insects?

Earlier work demonstrated that phenoxy–phenyl compounds such as fenoxycarb and thyroxine mimicked the effects of JH III in causing a reduction in volume of the follicle cells of Locusta migratoria. While these compounds were only moderately effective, a derivative of thyroxine, 3,3′,5-triiodothyronine (T3) was as effective as JH III, and T3 has been shown to bind to the same membrane receptor and activate the same pathway as JH III. The current paper shows that other thyroxine derivatives vary in activity. 3,3′,5′-Triiodothyronine (reverse T3) is inactive. 3,5-Diiodothyronine (T2) is more active than JH III, while its relatives (iodines at 3′,5′ or at 3,3′) are inactive. When follicles are exposed in vitro to rhodamine conjugated T3, the fluorescent compound can be seen to enter the cells and accumulate there: this process is inhibited by cycloheximide or by a temperature of 0°C. The accumulation is antagonised by JH III but not JH I (which does not bind to the JH III membrane receptor) and by an antiserum raised against the putative membrane receptor protein. The action of T3, but not T2, is inhibited by 6-n-propyl-2-thiouracil or by aurothioglucose, both known to inhibit deiodinases. The activity of T3, but not of T2, increases with time of exposure to the follicle cells. These facts suggest that T3 enters the cells by receptor mediated endocytosis and is converted to a more active compound. Immunoreactivity to T3, but not thyroxine, can be detected in the haemolymph of locusts, and the titre varies slightly with the gonotrophic cycle. The food shows immunoreactivity for both thyroxine and T3. These findings suggest that thyroid hormones are ingested by locusts and have the potential to be used as hormonal signals in the control of egg production.