期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：9
页码：3744-3747
DOI：10.1073/pnas.88.9.3744
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Various tissues excised from nymphs of the tick Ornithodoros parkeri at the time of epicuticle deposition were incubated in vitro. The medium from the incubation of salivary glands, coxal glands, synganglion, testis, midgut, and fat body associated with tracheal trunk showed little or no ecdysteroid immunoreactivity. Only medium from incubated integument contained ecdysteroids. The following evidence indicated that epidermal cells are the source of ecdysone: (i) when dorsal and/or ventral integuments were incubated separately, both produced ecdysteroid immunoreactive material during the course of incubation. As compared with the ecdysteroid content in the integument before incubation, the amount of ecdysteroids produced after a 24-h incubation increased 4- to 7-fold; (ii) enzymatic hydrolysis showed that neither highly polar ecdysteroid conjugates nor apolar conjugates were stored in the integument; (iii) histological and scanning electron microscope observations demonstrated that these excised integuments consisted of newly deposited epicuticle and epidermis as well as some fat body cells; (iv) HPLC RIA showed that the integument with associated fat body produced ecdysone and 20-hydroxyecdysone, while the integument produced only ecdysone after removing fat body. Presumably, ecdysone secreted by epidermis was converted into 20-hydroxyecdysone by fat body.
