Percorrer por autor "Martin, T. J."
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- Immunochemical detection of parathyroid hormone-related protein in the saccus vasculosus of a teleost fishPublication . Devlin, A. J.; Danks, J. A.; Faulkner, M. K.; Power, Deborah; Canario, Adelino V. M.; Martin, T. J.; Ingleton, P. M.Using antisera to regions of human parathyroid hormone- related protein (PTHrP) the saccus vasculosus (SV) of the sea bream (Sparus aurata) has been shown to contain immunoreactive PTHrP. By immunohistochemistry (IHC) the epithelial coronet cells in fixed and waxembedded SV tissue reacted with antisera to the prepro region of human PTHrP (−13 to +2), the N-terminus PTHrP (1–16), and the midmolecule PTHrP (50–69). Sodium dodecyl sulfate–polyacrylamide gel electrophoresis of saccus extracts and incubation media contained two major proteins of 14.3 and 15 kDa. By Western blotting these two proteins both reacted with the three antisera used for IHC, suggesting that they are immunochemically similar to human PTHrP (1–84). Ultrastructurally the coronet cells of Sparus saccus vasculosus resembled coronet cells described for other teleosts, with an abundant smooth endoplasmic reticulum (SER) which was more highly organized in the coronets. IHC at EM level showed reaction mainly with the membranes of the SER. These results suggest that S. aurata saccus vasculosus may produce a PTHrP-like molecule similar to human PTHrP.
- Parathyroid hormone-related protein and somatolactin in sea bream (Sparus aurata) brain and pituitaryPublication . Ingleton, P. M.; Power, Deborah; Canario, Adelino V. M.; Martin, T. J.; Danks, J. A.Parathyroid hormone-related protein (PTHrP) and somatolactin (SL) are both peptides that have been located in PAS+ve pars intermedia (PI) cells of teleost fishes. In mammals and the chick PTHrP is a hypercalcaemic factor causing lysis of bone calcified matrix and inhibiting phosphate excretion via the kidney. Functions of PTHrP in fishes are unknown but SL stimulates phosphate re-absorption by flounder kidney tubule cells1 and low ambient calcium activates PI cells of trout pituitaries.2 It appears possible that both peptides have some similar functions. They only share incidental amino acid homologies, so we have examined brain and pituitaries of sea bream for their distribution using specific antiserum to chum salmon SL (generous gift of H. Kawauchi) and to two regions of human PTHrP (1–16 ) and (50–69).
- Parathyroid hormone-related protein in lower vertebratesPublication . Danks, J. A.; Trivett, M. K.; Power, Deborah; Canario, Adelino V. M.; Martin, T. J.; Ingleton, P. M.1. Parathyroid hormone-related protein (PTHrP) is an important mediator of humoral hypercalcaemia of malignancy in humans. Normal human subjects have very low levels of PTHrP in their circulation. 2. Parathyroid hormone-related protein has recently been demonstrated in high levels in the circulation and tissues of the sea bream and the dogfish, leading to the hypothesis that PTHrP may be a 'classical' hormone in fish. 3. Immunohistochemistry and in situ hybridization were performed to investigate the evolutionary history of PTHrP. Tissues were examined from a number of lower vertebrates, including lungfish, lamprey and several species of bony and cartilaginous fish. Parathyroid hormone-related protein was localized to the skin and to kidney tubules in all animals studied. In the developing lungfish, PTHrP was observed in the notochord, developing brain and skeletal muscle layers. These results suggest that PTHrP is of ancient origin and has a basic and fundamental function in vertebrates.