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| Author(s): |
Daniela Dantas David
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Biociências (IBIOC/SB) |
| Defense date: | 2023-10-06 |
| Examining board members: |
Ana Maria de Lauro Castrucci;
Samuel Coelho de Faria;
Fábio Everton Maciel;
Rodrigo Schveitzer
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| Advisor: | Ana Maria de Lauro Castrucci |
| Abstract | |
Environmental cues can generate changes in physiological processes of crustaceans, such as the molting cycle. The molting process is a cyclic event subdivided into 5 main stages and each of them presents distinct characteristics that lead to specific physiological responses during this cycle. This process is mainly regulated by hormones produced in the neuroendocrine complex, the X-organ / sinus gland, located in the eyestalk, and the Y-organ, located in the cephalothorax. The hepatopancreas, being the main metabolic organ and presenting changes throughout the molting cycle, presents itself as an important target of the molting cycle. Given the importance of the crustacean molting cycle and its possible modulation in response to temperature, we aimed to investigate regulatory mechanisms in the intermolt and pre-molt stages of Callinectes sapidus (blue crab) facing thermal stimuli below and above the thermo-neutral condition. In this context, the morphology of the hepatopancreas, the concentration of ecdysteroids, cholesterol and circulating triglycerides in the hemolymph, the expression of key genes, and the proteogenomics of the species were analyzed. More pronounced changes in the hepatopancreas were seen in premolt specimens between temperatures, although they also occur in intermolt, but more subtly. Ecdysteroid levels were considerably reduced when premolt animals were subjected to cold. Among metabolites, cholesterol showed a difference between stages and its concentration was affected by temperature in premolt animals, while triglycerides were distiguished between stage at the the highest thermal condition. The expression of heat shock proteins (HSPs) was mainly altered in the hepatopancreas and showed to be dependent on temperature and molt stage. High expression of HSPs in the Y-organ occurred when premolt animals were subjected to cold. Ecdysteroid receptors in the eyestalk were more expressed in intermolt compared to premolt and temperature does not seem to affect this response. Unlikely its expression in the hepatopancreas was significantly higher when premolt animals were stimulated by cold. The synthesis of molt inhibiting hormone (MIH) appears to be constitutive, since different stages and temperatures did not cause changes; however, its receptor in the Y-organ underwent a reduction in gene expression in pre-molt animals subjected to cold, being also lower compared to intermolt specimens under the same condition. The crustacean hyperglycemic hormone (CHH) showed an increase in its expression when intermolt animals were subjected to a temperature above control condition, either between tenperatures at the same stage or at the same temperature in another stage, premolt. Proteogenomics allowed us to correlate data obtained so far with protein content of eyestalk which revealed differences in the abundance of major proteins between the evaluated stages: cellular energy homeostasis and cuticle structural alteration processes associated with premolt and intermolt respectively. An intermolt phenotype was observed in both the circulating ecdysteroid levels and the cluster analysis between molt stages under 3 temperatures. As for heat shock proteins, they were reduced in pre-molt animals subjected to cold. Definitively, the peptide hormones MIH and CHH proved to be reduced during intermolt compared to premolt stages suggesting increased release by the sinus gland. Our results demonstrated that temperature is an effective modulator of responses related to the molting cycle at various levels, and that temperature below the control condition caused a greater effect on the evaluated responses in relation to the thermo-stable condition, especially when the animal is in the pre-molt stage. (AU) | |
| FAPESP's process: | 18/23043-0 - Photo- and termo-reception systems in the Blue Crab, Callinectes sapidus (Crustacea Brachyura), and their relationship with the molt cycle |
| Grantee: | Daniela Dantas David |
| Support Opportunities: | Scholarships in Brazil - Doctorate |