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| Author(s): |
Marina Rincon Sartori
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Rio Claro. 2016-11-29. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro |
| Defense date: | 2016-09-26 |
| Advisor: | Augusto Shinya Abe |
| Abstract | |
During the reptilian embryonic development a progressive change in oxygen demand occurs as the embryos differentiate new tissue and grow. Moreover, reptilian eggs are susceptible to environmental changes, especially in temperature, that directly influences metabolic processes in embryos. Studies have shown that under constant temperatures embryonic reptiles present increasing levels of oxygen uptake, in three distinct patterns: exponential, sigmoidal, and in peak. In order to match oxygen supply and demand there might be accompanying cardiovascular adjustments in each stage of the embryonic period. In adult organisms different levels of sympathetic and parasympathetic control of the heart, driven by neurotransmitters, promotes accelerations or reductions in heart rate (fH), that ultimately alter the oxygen provision to embryonic tissues. However, the neural system is not completely formed during the embryonic development and cardiovascular regulatory mechanisms at this phase are not well understood. In this study we aimed to determine the patterns of metabolism (VO2) and fH in embryos of the green iguana,Iguana iguana. We also assessed the relationship between the VO2 and fH and chonotropic effects of temperature during the embryonic period.Finally, we investigated the autonomic control of the heart in embryos of iguanas and another lizard, the tegu (Salvator merianae), which belongs to another clade of the order Squamata. Our results show that in embryonic reptiles: i. a direct coupling between the metabolic rate and fH is absent throughout the embryonic incubation, ii. there is a direct effect of temperature on thefH and the depth in which nests are buried prevent major temperature changes, iii. there is an indication that cardiac receptors are present very early in development and iv. the control of the heart is mainly promoted by an adrenergic tonus via circulating cathecolamines, and the onset of cholinergic tonus is delayed, occurring only close to hatching which may be related to the ventilatory rhythm and the need to control cardiorespiratory interactions. (AU) | |
| FAPESP's process: | 12/16537-0 - Cardiovascular autonomic control and metabolism in lizard embryos (Reptilia; Lepidosauria) |
| Grantee: | Marina Rincon Sartori |
| Support Opportunities: | Scholarships in Brazil - Doctorate |