Banca de DEFESA: ANDRESSA APARECIDA DE LIMA REIS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDRESSA APARECIDA DE LIMA REIS
DATE: 19/12/2024
TIME: 08:30
LOCAL: Sala Prof. Laerte Grisi e https://meet.google.com/pas-idvv-ayq
TITLE:

Ultrastructural characterization and in vitro activity of fluazuron and novaluron on Amblyomma sculptum hemocytes after evaluation of reproductive efficiency

KEY WORDS:

Tick, benzoylphenylureas, hemolymph

PAGES: 129
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SUMMARY:

The tick Amblyomma sculptum has a wide geographic distribution, high impact on animal health and transmission of zoonotic diseases, which highlight the importance of studying and implementing effective control measures to mitigate the risks associated with this species. Despite this, information on biological aspects of this tick, such as hemocyte dynamics and the possible effects of chemical interference, is still scarce. The objectives of this study were to characterize the ultrastructure of different types of hemocytes in the hemolymph of engorged females of A. sculptum, to evaluate the reproductive efficiency of engorged females against fluazuron and novaluron, and to analyze the challenges of the cellular immune response through the in vitro action of these insect growth disruptors, evaluating quantitatively and morphologically the hemolymph cells. Hemolymph samples were collected by piercing the cuticle in the dorsal region. The identification and ultrastructural analysis of hemocytes was performed using transmission electron microscopy (TEM). The in vitro evaluation of the reproductive efficiency of engorged females of A. sculptum was performed after immersion in different concentrations of fluazuron and novaluron. For the cellular immune response to in vitro challenges, immersion tests were performed with engorged females of A. sculptum in the control and treated groups at concentrations of 7.81, 250 and 4000μg.mL-1 of fluazuron and 1250, 10000 and 40000μg.mL-1 of novaluron. At this stage, the hemolymph was collected at 24h and 48h after immersion. The total hemocyte count was performed in a Neubauer chamber and the determination of the frequency of each cell type was performed by preparing and analyzing hemolymph smears. Four morphologically distinct cell types were identified in females of A. sculptum through TEM: prohemocytes, plasmatocytes, granulocytes and spherulocytes. In the analysis of reproductive efficiency, the values obtained from the concentration of 250 μg.mL-1 of fluazuron achieved satisfactory efficacy, reaching 100% efficacy at the concentration of 4000 μg.mL-1. The results with novaluron did not present significant changes, with the highest concentration achieving 11.4% efficacy. After analyzing the cellular response, it was found that fluazuron promoted a significant decrease in total hemocytes at the concentration of 4000 μg.mL-1 after 48h, as well as increasing the frequency of spherulocytes. Novaluron did not cause changes in total hemocyte counts, however, within 24h, it caused a significant increase in prohemocytes at concentrations of 10,000 and 40,000 μg.mL-1, and within 48h it caused an increase in plasmatocytes and a decrease in granulocytes at concentrations of 10,000 and 40,000 μg.mL-1. In TEM, both insect growth disruptors were able to promote morphological and ultrastructural changes in the phagocytic hemocytes of A. sculptum. It is concluded that from TEM it was possible to characterize four cell types of A. sculptum: prohemocytes, plasmatocytes, granulocytes and spherulocytes. At the highest concentration, fluazuron was able to inhibit larval hatching, while novaluron was not able to act satisfactorily on reproductive efficiency. Furthermore, fluazuron and novaluron were able to promote cellular changes in the hemolymph of engorged female A. sculptum ticks after in vitro exposure. This is the first study to investigate the ultrastructural characteristics of hemocytes from  A. sculptum.

COMMITTEE MEMBERS:
Presidente - 1173660 - FABIO BARBOUR SCOTT
Interna - 2221855 - PATRICIA SILVA GOLO
Interna - 2929889 - THAIS RIBEIRO CORREIA AZEVEDO
Externo à Instituição - JOSE RECK JUNIOR - OUTRO
Externo à Instituição - ISABELLA VILHENA FREIRE MARTINS - UFES
Externo à Instituição - GUILHERME MARCONDES KLAFKE
Externa à Instituição - EMILY MESQUITA DA SILVA