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Developmental profile of the ecdysone receptor mediating salivary gland degeneration in an ixodid tick (Acari: Ixodidae)
s72 Pl-13
Pl-15
cDNA cloning of GTH receptor family from ovaries of the starfish Asterinapectinifera.
Developmental profile of the ecdysone receptor mediating salivary gland degeneration in an ixodid tick (Atari: Ixodidae).
Hirai T’, Oba Y2, Yoshikuni M2, Nagahama Y2 and Mita3.4 ‘Dept. of Biol. Sci., Teikvo Univ. of Sci. and Tech., Uenohara 4090133, ‘Lab. of Reprod. Biol., Nat. Inst. of Basic Biol., Okazaki 4448585, ‘Dept. of Biol., Sch. of Educ., Waseda Univ., Shinjuku-ku, Tokyo 169-8050, Teikyo Jun. Coil., Shibuya-ku, Tokyo 151-0071,
Japan In starfish, resumption of meiosis in immature oocytes is induced by maturation-inducing hormone, I-methyladenine (lMA). l-MA is produced by ovarian follicle cells following stimulation by another peptide hormone (gonad-stimulating substance, GSS) released from the radial nerve. The action of GSS on l-MA production in follicle cells appears to be mediated by its receptor, G-proteins and adenylyl cyclase. It was suggested that a G-protein coupled (seven transmembrane type) receptor is involved in GSS signal transduction, similarly to the pituitary-gonadal axis in vertebrate. Using degenerate probes derived from consensus sequences of the mammalian glycoprotein hormone (GTH and TSH) receptors, we cloned the cDNA from ovaries of the starfish Asterina pectinifra. The cDNA showed striking structural homology with members of glycoprotein hormone receptor family in a transmembrane region, and contained a very large extracellular region. Expression was observed in testis and isolated ovarian follicle cells. Thus, it seems likely that the GTH receptor family gene is related to GSS receptor in ovarian follicle cells.
Kaufman, Reuben and Mao, Helen* Dept. Biological Sciences, University of Alberta, Edmonton, Canada T6G 2E9 *Current address: Dept. Biology, Indiana University, Bloomington Indiana, U.S.A. 47405 4-5 days of a female ixodid tick’s engorging on a huge blood meal, the salivary glands undergo autolysis. Tissue degeneration is caused by 20hydroxyecdysone (20E) acting via an ecdysone receptor (EWUSP; Mao et al., 1995, Gen. Comp. Endocrinol. 99: 340-348; Mao & Kaufman, 1998, Insect Biochem. Mol. Biol. 28: 947-957 and Mao & Kaufman, 1999, Insect Biochem. Mol. Biol. 29: 3342). Here we demonstrate that the act of feeding induces the development of an EcR/USP system in the salivary gland. Maximal development occurs toward the latter part of feeding and coincides with a peak concentration of haemolymph ecdysteroid (about 50 ng 20E-equivalents per ml as determined by RIA). This receptor system shows similarities to the systems of other arthropods.
Within
Pl-14
PI-16
Bradykinin receptors in the gastrointestinal tracts of trout and cod: Evidence for a novel type of receptor
Modulation of tension in Iguana iguana aortic rings by calcitonin gene-related peptide (CGRP).
Jensen J, Shahbazi F, Holmgren S and Conlon JM* Giiteborg University, Department of Zoophysiology, Giiteborg, Sweden. *Department of Biomedical Sciences, Creighton University, Omaha, NE, U.S.A.
Kline LW Department of Dentist@Physiology, University Edmonton, Alberta, Canada T6G 2N8
The actions of bradykinin (BK) on mammalian smooth muscle are mediated through interaction with BI and BZ receptors. Bzreceptors are preferentially activated by BK and Lys’-BK, whereas B,-receptors are more responsive to analogs lacking the C-terminal arginine (desArgg-BK and desArgg-LysO-BK). In this study the myotropic activities of [Arg’,T$,Leu’]-BK (RBK), isolated from plasma of two teleosts (rainbow trout and cod), and its structural analogs were examined. Both RBK and desArg’-RBK produced dose-dependent contractions of the cod intestine, while desArg’-RBK was inactive, thus indicating a receptor similar to the mammalian Bz-receptor. In contrast, desArg’-RBK was much less effective than RBK in producing contractions of the trout stomach but desArg’-RBK was active. To identify the amino acid residues in RBK important for recognition by the trout receptor, the myotropic activity of analogs containing Ala-substitutions was studied. Substitution of Gly4 or Trp’ produced inactive analogs and a >50-fold decrease in potency was observed with substitution of Argo. The results demonstrate that the ligand binding properties of the trout BK receptor differ considerably from the mammalian BI-and Bz-receptors.
of Alberta,
In lizards the regulation of peripheral vasodilation has not been examined in detail. In snakes angiotensin II causes contraction of vascular smooth muscle (vsm) by acting on its own receptors, stimulating the release of norepinephrine (NE), or both. In turtles, nitric oxide (NO) mediates the increase in cerebral blood flow stimulated by acetylcholine; however, anoxia-induced increases in cerebral blood flow do not rely on NO. We have shown that CGRP relaxes cholecystokinin-induced tension in iguana gallbladder strips. The purpose of this study was to determine if CGRP had a role in relaxing vsm in iguana thoracic aortic rings. CGRP relaxed phenylephrine (PE)-induced tension by 81+7.3%. The NO synthase inhibitor, L-NAME, had no significant effect on the CGRP-induced relaxation. Neither sodium nitroprusside, a NO donor, nor dibutyrl cGMP had any effect. This suggested that NO was not mediating the CGRP effect. Rp-CAMPS, a CAMP analog which blocks PKA, significantly (p
Pl-15
cDNA cloning of GTH receptor family from ovaries of the starfish Asterinapectinifera.
Developmental profile of the ecdysone receptor mediating salivary gland degeneration in an ixodid tick (Atari: Ixodidae).
Hirai T’, Oba Y2, Yoshikuni M2, Nagahama Y2 and Mita3.4 ‘Dept. of Biol. Sci., Teikvo Univ. of Sci. and Tech., Uenohara 4090133, ‘Lab. of Reprod. Biol., Nat. Inst. of Basic Biol., Okazaki 4448585, ‘Dept. of Biol., Sch. of Educ., Waseda Univ., Shinjuku-ku, Tokyo 169-8050, Teikyo Jun. Coil., Shibuya-ku, Tokyo 151-0071,
Japan In starfish, resumption of meiosis in immature oocytes is induced by maturation-inducing hormone, I-methyladenine (lMA). l-MA is produced by ovarian follicle cells following stimulation by another peptide hormone (gonad-stimulating substance, GSS) released from the radial nerve. The action of GSS on l-MA production in follicle cells appears to be mediated by its receptor, G-proteins and adenylyl cyclase. It was suggested that a G-protein coupled (seven transmembrane type) receptor is involved in GSS signal transduction, similarly to the pituitary-gonadal axis in vertebrate. Using degenerate probes derived from consensus sequences of the mammalian glycoprotein hormone (GTH and TSH) receptors, we cloned the cDNA from ovaries of the starfish Asterina pectinifra. The cDNA showed striking structural homology with members of glycoprotein hormone receptor family in a transmembrane region, and contained a very large extracellular region. Expression was observed in testis and isolated ovarian follicle cells. Thus, it seems likely that the GTH receptor family gene is related to GSS receptor in ovarian follicle cells.
Kaufman, Reuben and Mao, Helen* Dept. Biological Sciences, University of Alberta, Edmonton, Canada T6G 2E9 *Current address: Dept. Biology, Indiana University, Bloomington Indiana, U.S.A. 47405 4-5 days of a female ixodid tick’s engorging on a huge blood meal, the salivary glands undergo autolysis. Tissue degeneration is caused by 20hydroxyecdysone (20E) acting via an ecdysone receptor (EWUSP; Mao et al., 1995, Gen. Comp. Endocrinol. 99: 340-348; Mao & Kaufman, 1998, Insect Biochem. Mol. Biol. 28: 947-957 and Mao & Kaufman, 1999, Insect Biochem. Mol. Biol. 29: 3342). Here we demonstrate that the act of feeding induces the development of an EcR/USP system in the salivary gland. Maximal development occurs toward the latter part of feeding and coincides with a peak concentration of haemolymph ecdysteroid (about 50 ng 20E-equivalents per ml as determined by RIA). This receptor system shows similarities to the systems of other arthropods.
Within
Pl-14
PI-16
Bradykinin receptors in the gastrointestinal tracts of trout and cod: Evidence for a novel type of receptor
Modulation of tension in Iguana iguana aortic rings by calcitonin gene-related peptide (CGRP).
Jensen J, Shahbazi F, Holmgren S and Conlon JM* Giiteborg University, Department of Zoophysiology, Giiteborg, Sweden. *Department of Biomedical Sciences, Creighton University, Omaha, NE, U.S.A.
Kline LW Department of Dentist@Physiology, University Edmonton, Alberta, Canada T6G 2N8
The actions of bradykinin (BK) on mammalian smooth muscle are mediated through interaction with BI and BZ receptors. Bzreceptors are preferentially activated by BK and Lys’-BK, whereas B,-receptors are more responsive to analogs lacking the C-terminal arginine (desArgg-BK and desArgg-LysO-BK). In this study the myotropic activities of [Arg’,T$,Leu’]-BK (RBK), isolated from plasma of two teleosts (rainbow trout and cod), and its structural analogs were examined. Both RBK and desArg’-RBK produced dose-dependent contractions of the cod intestine, while desArg’-RBK was inactive, thus indicating a receptor similar to the mammalian Bz-receptor. In contrast, desArg’-RBK was much less effective than RBK in producing contractions of the trout stomach but desArg’-RBK was active. To identify the amino acid residues in RBK important for recognition by the trout receptor, the myotropic activity of analogs containing Ala-substitutions was studied. Substitution of Gly4 or Trp’ produced inactive analogs and a >50-fold decrease in potency was observed with substitution of Argo. The results demonstrate that the ligand binding properties of the trout BK receptor differ considerably from the mammalian BI-and Bz-receptors.
of Alberta,
In lizards the regulation of peripheral vasodilation has not been examined in detail. In snakes angiotensin II causes contraction of vascular smooth muscle (vsm) by acting on its own receptors, stimulating the release of norepinephrine (NE), or both. In turtles, nitric oxide (NO) mediates the increase in cerebral blood flow stimulated by acetylcholine; however, anoxia-induced increases in cerebral blood flow do not rely on NO. We have shown that CGRP relaxes cholecystokinin-induced tension in iguana gallbladder strips. The purpose of this study was to determine if CGRP had a role in relaxing vsm in iguana thoracic aortic rings. CGRP relaxed phenylephrine (PE)-induced tension by 81+7.3%. The NO synthase inhibitor, L-NAME, had no significant effect on the CGRP-induced relaxation. Neither sodium nitroprusside, a NO donor, nor dibutyrl cGMP had any effect. This suggested that NO was not mediating the CGRP effect. Rp-CAMPS, a CAMP analog which blocks PKA, significantly (p