Seasonal Changes in Sex and Adrenal Steroid Hormones of Gopher Tortoises (Gopherus polyphemus)

Ott, Jeannine A.; Mendonça, Mary T.; Guyer, Craig; Michener, William K.

doi:10.1006/gcen.1999.7419

Cited by 70 publications

(29 citation statements)

References 26 publications

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“…First, E2 is the primary hormone responsible for stimulating the liver to produce vitellogenins, or egg-yolk proteins (reviewed in Ho et al, 1982), and increases in E2 are correlated with vitellogenic activity in turtles (Ott et al, 2000), alligators (Guillette et al, 1997), lizards (Edwards and Jones, 2001;Radder et al, 2001;, and snakes (Bonnet et al, 1994;Whittier et al, 1987). Second, in creases in E2 commonly occur during the mating season because E2 can stimulate attractivity or receptivity of female reptiles Whittier and Tokarz, 1992).…”

Section: Discussionmentioning

confidence: 99%

“…The function of T in female reptiles is poorly understood (Staub and De Beer, 1997). An increase in T is evident in females of many taxa during the mating/vitellogenic period (turtles: Hamann et al, 2002;Ott et al, 2000;alligators: Guil lette et al, 1997;tuatara: Cree et al, 1992;lizards: Ed wards and Jones, 2001;and snakes: Saint-Girons et al, 1993;Whittier et al, 1987), but the function of this increase is unknown.…”

Section: Discussionmentioning

confidence: 99%

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Seasonal steroid hormone levels and their relation to reproduction in the Western Diamond-backed Rattlesnake, Crotalus atrox (Serpentes: Viperidae)

Taylor

DeNardo

Jennings

2004

General and Comparative Endocrinology

107

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We report seasonal variation in steroid hormone levels in blood samples from free ranging Western Diamond backed Rattle snakes (Crotalus atrox), and the relationship between these hormones and events in the reproductive cycle. At a field site in the Sonoran Desert of south central Arizona, we collected monthly blood samples over the course of two active seasons from 17 ra diotelemetered females, and over three active seasons from 103 randomly encountered males. We used radioimmunoassay to measure plasma levels of 17b estradiol, progesterone, corticosterone, and testosterone in samples from females, and corticosterone and testosterone in samples from males. Non reproductive females have consistently low levels of circulating 17b estradiol, pro gesterone, and testosterone throughout the year. In reproductive females, 17b estradiol levels increase dramatically and testosterone levels increase modestly during vitellogenesis in April and May, while progesterone levels increase dramatically at ovulation in June and then steadily decline until parturition in August. Corticosterone levels appear relatively constant in non reproductive females, whereas reproductive females show increased levels at the end of gestation. Plasma testosterone levels in males are low in early summer and are elevated during spring and late summer, corresponding to the two mating periods of C. atrox. Plasma cortico sterone levels in males did not vary seasonally and were not related to testosterone levels.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Seasonal steroid hormone levels and their relation to reproduction in the Western Diamond-backed Rattlesnake, Crotalus atrox (Serpentes: Viperidae)

Taylor

DeNardo

Jennings

2004

General and Comparative Endocrinology

107

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“…Additionally, to assist in the evaluation of both animal and environmental health, testosterone has also been linked to body condition, home range size, and activity in other reptiles [9,60,68], but this has yet to be assessed in box turtles. In females of other turtle species, estradiol-17b (E2) generally peaks prior to vitellogenesis, with multiple peaks for multiclutched species [8,36,45]. A destructive study on a limited number of box turtles suggested that ovaries reach their maximum weight in May, then reduce in June and July following ovulation [1] in what appeared to be a single annual cycle.…”

Section: Introductionmentioning

confidence: 97%

Seasonal variations in plasma vitellogenin and sex steroids in male and female Eastern Box Turtles, Terrapene carolina carolina

Currylow

Tift

Meyer

et al. 2013

General and Comparative Endocrinology

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“…The sex steroids E 2 , P 4 , and testosterone, often show seasonal cyclicity and are highly studied regulators of reproduction in most vertebrates, playing key roles in the production and maturation of gametes (Jones & Swain 1996, Ott et al 2000, Edwards & Jones 2001, Brasfield et al 2008, Wack et al 2008, Smith et al 2010. In female alligators, as with nearly all oviparous vertebrates, E 2 triggers the hepatic production of vitellogenin (VTG), the primary precursor of egg yolk protein (Ho et al 1982, Ho 1987, Guillette et al 1997.…”

Section: Introductionmentioning

confidence: 99%

The reproductive hormone cycle of adult female American alligators from a barrier island population

Hamlin

Lowers²,

Kohno

et al. 2014

Reproduction

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Comparatively, little data are available detailing the geographic variation that exists in the reproductive endocrinology of adult alligators, especially those living in barrier islands. The Merritt Island National Wildlife Refuge (MI) is a unique barrier island environment and home to the Kennedy Space Center (FL, USA). Seasonal patterns of sex steroids were assessed in adult female American alligators from MI monthly from 2008 to 2009, with additional samples collected at more random intervals in 2006, 2007, and 2010. Plasma 17b-estradiol and vitellogenin concentrations peaked in April, coincident with courtship and mating, and showed patterns similar to those observed in adult female alligators in other regions. Plasma concentrations of progesterone, however, showed patterns distinctly different than those reported for alligator populations in other regions and remained relatively constant throughout the year. Plasma DHEA peaked in July around the time of oviposition, decreased in August, and then remained constant for the remaining months, except for a moderate increase in October. Circulating concentrations of DHEA have not been previously assessed in a female crocodilian, and plasma concentrations coincident with reproductive activity suggest a reproductive and/or behavioral role. Interestingly, plasma testosterone concentrations peaked in May of 2008, as has been shown in female alligator populations in other regions, but showed no peak in 2009, demonstrating dramatic variability from year to year. Surveys showed 2009 to be particularly depauperate of alligator nests in MI, and it is possible that testosterone could serve as a strong indicator of breeding success.

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Seasonal Changes in Sex and Adrenal Steroid Hormones of Gopher Tortoises (Gopherus polyphemus)

Cited by 70 publications

References 26 publications

Seasonal steroid hormone levels and their relation to reproduction in the Western Diamond-backed Rattlesnake, Crotalus atrox (Serpentes: Viperidae)

Seasonal steroid hormone levels and their relation to reproduction in the Western Diamond-backed Rattlesnake, Crotalus atrox (Serpentes: Viperidae)

Seasonal variations in plasma vitellogenin and sex steroids in male and female Eastern Box Turtles, Terrapene carolina carolina

The reproductive hormone cycle of adult female American alligators from a barrier island population

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