Insects on steroids.I was distressed to read that SCIENCE NEWS thinks there are no steroid hormone receptors in insects ("Ancient estrogen," SN: 8/11/01, p. 94). Granted, their reproduction is not regulated by steroids, but ecdysone Ecdysone The molting hormone of insects. It is a derivative of cholesterol. The most striking physiological activity of ecdysone is the induction of puffs (zones of gene activity) in giant chromosomes of the salivary glands and other organs of the midge , the molting molting, periodical shedding and renewal of the outer skin, exoskeleton, fur, or feathers of an animal. In most animals the process is triggered by secretions of the thyroid and pituitary glands. hormone, is certainly a steroid. There is some evidence that juvenile hormone, the hormone that regulates development and sometimes reproduction, acts through a steroidlike-receptor pathway. Other developmental regulators like retinoic acid retinoic acid /ret·i·no·ic ac·id/ (ret?i-no´ik) an oxidized derivative of retinol, believed to be the form of vitamin A that plays a role in the development and growth of bone and in the maintenance of normal epithelial structures. and thyroid hormone Thyroid hormone Any of the chemical messengers produced by the thyroid gland, including thyrocalcitonin, a polypeptide, and thyroxine and triiodothyronine, which are iodinated thyronines. See Hormone, Thyrocalcitonin, Thyroid gland, Thyroxine also work through steroidlike receptors. Perhaps the early evolutionary steps the article seeks are in the invertebrates after all. Elaine Roberts Colorado State University Fort Collins, Colo. |
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