The reactions of developing Snapping Turtles, Chelydra serpentina serpentina (Linné), to thiourea

Dimond, Sister Marie Therese

doi:10.1002/jez.1401270106

Cited by 19 publications

(15 citation statements)

References 33 publications

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“…In this study, lower incubation temperatures increase incubation time (Table 1; Yntema 1978), and T3 decreases incubation time (Table 3). This result nicely complements an earlier study in which C. serpentina embryos responded to thiourea (a goitrogen or antithyroidal) treatment with slowed developmental rates and increased incubation times (Dimond 1954). Our study also found that T3 treatment decreases hatchling mass (Table 3), which otherwise increases with declining egg temperature down to 24ЊC (Table 1; reviews Figure 2.…”

Section: Effects Of Exogenous Thyroid Hormonessupporting

confidence: 90%

“…The thyroid gland differentiates before this period and responds to antithyroidal agents during this period, suggesting that the gland is functional (Dimond 1954;Ewert 1985). Stages 18-19 are within the sex-determining phase of development (Yntema 1976(Yntema , 1979 and just before the phase that displays positive metabolic compensation (Birchard and Reiber 1995).…”

Section: Thyroid Hormone Application To Eggsmentioning

confidence: 98%

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Embryonic Temperature Affects Metabolic Compensation and Thyroid Hormones in Hatchling Snapping Turtles

O’Steen

Janzen

1999

Physiological and Biochemical Zoology

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Temperature acclimation of adult vertebrates typically induces changes in metabolic physiology. During early development, such metabolic compensation might have profound consequences, yet acclimation of metabolism is little studied in early life stages. We measured the effect of egg incubation temperature on resting metabolic rate (RMR) and blood thyroid hormone levels of hatchling snapping turtles (Chelydra serpentina). Like many reptiles, snapping turtles have temperature-dependent sex determination (TSD), in which embryonic temperature determines sex. Therefore, we designed the experiments to separately measure effects of temperature and of sex on the response variables. We incubated eggs in the laboratory at 21. 5 degrees, 24.5 degrees, 27.5 degrees, and 30.5 degrees C, producing both sexes, all males, both sexes, and all females, respectively. Hatchling RMR, when measured at a common temperature (either 25 degrees or 31 degrees C), was negatively correlated with egg temperature in both males and females, such that RMR of turtles from 21.5 degrees C-incubated eggs averaged 160% that of turtles from 30.5 degrees C-incubated eggs. These results indicate that egg temperatures induced positive metabolic compensation in both sexes. Thyroid hormone levels of hatchlings showed similar correlations with egg temperature; thyroxine level of turtles from 21.5 degrees C-incubated eggs averaged 220% that of turtles from 30.5 degrees C-incubated eggs. To examine the possibility that thyroid hormones contribute to positive metabolic compensation, we added triiodothyronine to eggs during mid-incubation. RMR of hatchlings from these treated eggs averaged 131% that of controls, consistent with the previous possibility. Moreover, the effects of embryonic temperature on metabolic physiology, in combination with effects on sex, can result in differences in RMR and thyroid hormone levels between male and female hatchling turtles. Such differences may be important to the ecology and evolution of TSD.

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Section: Effects Of Exogenous Thyroid Hormonessupporting

confidence: 90%

Section: Thyroid Hormone Application To Eggsmentioning

confidence: 98%

Embryonic Temperature Affects Metabolic Compensation and Thyroid Hormones in Hatchling Snapping Turtles

O’Steen

Janzen

1999

Physiological and Biochemical Zoology

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“…Conversely, chicken embryos treated with THs (or TSH) hatch earlier (Balaban and Hill, 1971; Oppenheim, 1973) and premature yolk sac retraction and pipping were noted on E19 after a single injection of T 3 or T 4 on E16 (Decuypere et al, 1991). Similar observations have been made in one non-avian sauropsid species, namely in snapping turtle embryos (Dimond, 1954). …”

Section: Thyroid Hormones and The Hatching Process Of Precocial Birdssupporting

confidence: 82%

“…This study suggests that, at least in the saltwater crocodile, the ontogenic pattern of THs may be similar to that seen in precocial birds. Based on the histology of the thyroid follicles of embryos toward and during hatching, this may also be the case in other reptile species (Dimond, 1954; Miller, 1963). The ontogenic changes seen in deiodinase activities in the embryonic saltwater crocodile also resemble those of the chicken, most notably the marked decrease in hepatic D3 activity that could contribute to increasing plasma T 3 levels toward hatching (Shepherdley et al, 2002b).…”

Section: Thyroid Hormone Levels In the Perihatch Periodmentioning

confidence: 96%

Hatching the Cleidoic Egg: The Role of Thyroid Hormones

Groef¹,

Grommen²,

Darras³

2013

Front. Endocrinol.

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A major life stage transition in birds and other oviparous sauropsids is the hatching of the cleidoic egg. Not unlike amphibian metamorphosis, hatching in these species can be regarded as a transition from a relatively well-protected “aqueous” environment to a more hazardous and terrestrial life outside the egg, a transition in which thyroid hormones (THs) (often in concert with glucocorticoids) play an important role. In precocial birds such as the chicken, the perihatch period is characterized by peak values of THs. THs are implicated in the control of muscle development, lung maturation and the switch from chorioallantoic to pulmonary respiration, yolk sac retraction, gut development and induction of hepatic genes to accommodate the change in dietary energy source, initiation of thermoregulation, and the final stages of brain maturation as well as early post-hatch imprinting behavior. There is evidence that, at least for some of these processes, THs may have similar roles in non-avian sauropsids. In altricial birds such as passerines on the other hand, THs do not rise significantly until well after hatching and peak values coincide with the development of endothermy. It is not known how hatching-associated processes are regulated by hormones in these animals or how this developmental mode evolved from TH-dependent precocial hatching.

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“…Normally, a spike in THs coincides with pipping, an initial break in the eggshell by the embryo. In contrast, exposure to thiourea, a known anti-thyroidal drug, in snapping turtle embryos causes a delay in hatching as well as a decreased growth rate and poor yolk absorption, all of which are known to be thyroid-dependent processes (Dimond, 1954). Thyroid hormonedependent hatching is also evident in reptiles.…”

Section: Hatching and Neonatal Growthmentioning

confidence: 99%