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John D. Newton - One of the best experts on this subject based on the ideXlab platform.
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Slow Estradiol-induced Vitellogenesis in the Tuatara, Sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (
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slow estradiol induced vitellogenesis in the tuatara sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (<3. 7 ng/mL and <3.8 ng/mL, respectively) during the 11 d. Several individuals captured 4-9 mo after administration of implants showed very high plasma levels of Vitellogenin (up to 59% of total plasma protein), calcium (up to 61 mmol/L), total protein (up to 108 g/L), and inorganic phosphate (up to 39 mmol/L); these ...
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variation in plasma constituents during the natural vitellogenic cycle of tuatara sphenodon punctatus
Comparative Biochemistry and Physiology B, 1991Co-Authors: Mark A. Brown, Alison Cree, John D. Newton, Geoffrey K Chambers, John F. CockremAbstract:Abstract 1. 1. The vitellogenic cycle of female tuatara was investigated by monitoring plasma levels of Vitellogenin, calcium, total protein, inorganic phosphate (P1) and cholesterol. 2. 2. Vitellogenin was not detected in females in the non-reproductive condition, but was found perenially in plasma of reproducing females during vitellogenesis, which normally lasts about 3 years out of the 4 year ovarian cycle. 3. 3. No large year-to-year variations were found in the plasma constituents measured and there was no correlation between the oestradiol peak at mating and plasma levels of Vitellogenin. 4. 4. The results provide further evidence that tuatara have an extraordinary prolonged and gradual vitellogenic cycle spanning several years for a single clutch of eggs. This type of reproductive cycle is unique among reptiles.
Alison Cree - One of the best experts on this subject based on the ideXlab platform.
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Slow Estradiol-induced Vitellogenesis in the Tuatara, Sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (
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slow estradiol induced vitellogenesis in the tuatara sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (<3. 7 ng/mL and <3.8 ng/mL, respectively) during the 11 d. Several individuals captured 4-9 mo after administration of implants showed very high plasma levels of Vitellogenin (up to 59% of total plasma protein), calcium (up to 61 mmol/L), total protein (up to 108 g/L), and inorganic phosphate (up to 39 mmol/L); these ...
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variation in plasma constituents during the natural vitellogenic cycle of tuatara sphenodon punctatus
Comparative Biochemistry and Physiology B, 1991Co-Authors: Mark A. Brown, Alison Cree, John D. Newton, Geoffrey K Chambers, John F. CockremAbstract:Abstract 1. 1. The vitellogenic cycle of female tuatara was investigated by monitoring plasma levels of Vitellogenin, calcium, total protein, inorganic phosphate (P1) and cholesterol. 2. 2. Vitellogenin was not detected in females in the non-reproductive condition, but was found perenially in plasma of reproducing females during vitellogenesis, which normally lasts about 3 years out of the 4 year ovarian cycle. 3. 3. No large year-to-year variations were found in the plasma constituents measured and there was no correlation between the oestradiol peak at mating and plasma levels of Vitellogenin. 4. 4. The results provide further evidence that tuatara have an extraordinary prolonged and gradual vitellogenic cycle spanning several years for a single clutch of eggs. This type of reproductive cycle is unique among reptiles.
Louis J. Guillette - One of the best experts on this subject based on the ideXlab platform.
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the reproductive cycle of the female american alligator alligator mississippiensis
General and Comparative Endocrinology, 1997Co-Authors: Louis J. Guillette, Allan R Woodward, Andrew D Crain, Greg R Masson, Brent D Palmer, Qui Youxiang, Edward F OrlandoAbstract:We examined ovarian and oviducal gross morphology and collected blood samples from wild female alligators in central Florida during most of the year. Females with vitellogenic follicles were observed throughout the year, although ovaries containing follicles larger than 15 mm were seen only during the spring and early summer (March‐June). We detected a poor relationship between female body size and the number of vitellogenic follicles whereas body size was significantly correlated with clutch size. Plasma samples were analyzed for (1) estradiol-17b (E2), testosterone (T), and corticosterone by specific radioimmunoassays; (2) Vitellogenin by onedimensional sodium dodecyl sulfate‐polyacrylamide gel electrophoresis; and (3) total protein, phosphorus, and calcium by spectrophotometric assays. Reproductively active females showed elevated plasma concentrations of E2 during the fall (September‐November) and spring (March‐May) whereas non-reproductively active females exhibited basal levels with no apparent peaks. Vitellogenin was detected in the plasma during the same months that plasma E2 concentrations were elevated. Elevated plasma Vitellogenin and E2 were not correlated with plasma total protein but were correlated with plasma calcium concentration. During late vitellogenesis, plasma T concentrations were elevated in reproductively active females coincident with a period of intense courtship and mating. Corticosterone plasma concentrations exhibit no significant monthly variation, nor apparent changes during various stages of reproductive activity although plasma concentrations were elevated during late gravidity. Our data suggest that female reproductive activity begins in the fall with an increase in plasma E2 concentration in September or October and vitellogenesis in October. Ovarian activity slows during winter and reactivates with the onset of spring. r 1997 Academic Press
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Slow Estradiol-induced Vitellogenesis in the Tuatara, Sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (
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slow estradiol induced vitellogenesis in the tuatara sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (<3. 7 ng/mL and <3.8 ng/mL, respectively) during the 11 d. Several individuals captured 4-9 mo after administration of implants showed very high plasma levels of Vitellogenin (up to 59% of total plasma protein), calcium (up to 61 mmol/L), total protein (up to 108 g/L), and inorganic phosphate (up to 39 mmol/L); these ...
John F. Cockrem - One of the best experts on this subject based on the ideXlab platform.
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Slow Estradiol-induced Vitellogenesis in the Tuatara, Sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (
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slow estradiol induced vitellogenesis in the tuatara sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (<3. 7 ng/mL and <3.8 ng/mL, respectively) during the 11 d. Several individuals captured 4-9 mo after administration of implants showed very high plasma levels of Vitellogenin (up to 59% of total plasma protein), calcium (up to 61 mmol/L), total protein (up to 108 g/L), and inorganic phosphate (up to 39 mmol/L); these ...
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variation in plasma constituents during the natural vitellogenic cycle of tuatara sphenodon punctatus
Comparative Biochemistry and Physiology B, 1991Co-Authors: Mark A. Brown, Alison Cree, John D. Newton, Geoffrey K Chambers, John F. CockremAbstract:Abstract 1. 1. The vitellogenic cycle of female tuatara was investigated by monitoring plasma levels of Vitellogenin, calcium, total protein, inorganic phosphate (P1) and cholesterol. 2. 2. Vitellogenin was not detected in females in the non-reproductive condition, but was found perenially in plasma of reproducing females during vitellogenesis, which normally lasts about 3 years out of the 4 year ovarian cycle. 3. 3. No large year-to-year variations were found in the plasma constituents measured and there was no correlation between the oestradiol peak at mating and plasma levels of Vitellogenin. 4. 4. The results provide further evidence that tuatara have an extraordinary prolonged and gradual vitellogenic cycle spanning several years for a single clutch of eggs. This type of reproductive cycle is unique among reptiles.
Mark A. Brown - One of the best experts on this subject based on the ideXlab platform.
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Slow Estradiol-induced Vitellogenesis in the Tuatara, Sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (
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slow estradiol induced vitellogenesis in the tuatara sphenodon punctatus
Physiological and Biochemical Zoology, 1991Co-Authors: Alison Cree, Mark A. Brown, Louis J. Guillette, John F. Cockrem, Geoffrey K Chambers, John D. NewtonAbstract:The vitellogenic response to exogenous estradiol-17β in wild male and female tuatara (Sphenodon punctatus) is extremely slow to induce. Tuatara given slowrelease implants containing 4-11 μg estradiol/g body mass showed a marked elevation in plasma estradiol concentrations within 2 d (to levels of up to 2,967 pg/mL) but no marked increases in plasma concentrations of calcium, total protein, or inorganic phosphate within 11 d. A small increase in the amount of electrophoretically detectable Vitellogenin in the plasma (expressed as a percentage of total plasma protein) was evident by 11 d. Plasma concentrations of progesterone in individual females and testosterone in individual males were low (<3. 7 ng/mL and <3.8 ng/mL, respectively) during the 11 d. Several individuals captured 4-9 mo after administration of implants showed very high plasma levels of Vitellogenin (up to 59% of total plasma protein), calcium (up to 61 mmol/L), total protein (up to 108 g/L), and inorganic phosphate (up to 39 mmol/L); these ...
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variation in plasma constituents during the natural vitellogenic cycle of tuatara sphenodon punctatus
Comparative Biochemistry and Physiology B, 1991Co-Authors: Mark A. Brown, Alison Cree, John D. Newton, Geoffrey K Chambers, John F. CockremAbstract:Abstract 1. 1. The vitellogenic cycle of female tuatara was investigated by monitoring plasma levels of Vitellogenin, calcium, total protein, inorganic phosphate (P1) and cholesterol. 2. 2. Vitellogenin was not detected in females in the non-reproductive condition, but was found perenially in plasma of reproducing females during vitellogenesis, which normally lasts about 3 years out of the 4 year ovarian cycle. 3. 3. No large year-to-year variations were found in the plasma constituents measured and there was no correlation between the oestradiol peak at mating and plasma levels of Vitellogenin. 4. 4. The results provide further evidence that tuatara have an extraordinary prolonged and gradual vitellogenic cycle spanning several years for a single clutch of eggs. This type of reproductive cycle is unique among reptiles.
