Banca de QUALIFICAÇÃO: ANDRESSA APARECIDA DE LIMA REIS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANDRESSA APARECIDA DE LIMA REIS
DATE: 05/11/2024
TIME: 09:00
LOCAL: Sala Prof. Laerte Grisi
TITLE:

Ultrastructural characterization and in vitro action of fluazuron and novaluron on hemocytes of Amblyomma sculptum. 

KEY WORDS:

Tick, benzoylphenylureas, hemolymph

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

The tick Amblyomma sculptum is involved in the transmission of pathogens that cause diseases in animals and humans. Its wide geographic distribution, high impact on animal health, and transmission of zoonotic diseases highlight the importance of studying and implementing effective control measures to mitigate the risks associated with this tick species. The aim of this study was to characterize the ultrastructure of different types of hemocytes in the hemolymph of engorged females of A. sculptum, assess the reproductive efficiency of engorged females in response to fluazuron and novaluron, and present and discuss 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 puncturing the dorsal region of the cuticle. The identification and ultrastructural analysis of hemocytes were performed using transmission electron microscopy (TEM). The in vitro assessment of the reproductive efficiency of engorged females of A. sculptum was conducted 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 control and treated groups at concentrations of 7.81, 250, and 4000 μg.mL^-1 of fluazuron and 1250, 10000, and 40000 μg.mL^-1 of novaluron. At this stage, hemolymph was collected at 24h and 48h after immersion. Total hemocyte counts were performed in a Neubauer chamber, and the frequency of each cell type was determined by preparing and analyzing hemolymph smears. Four morphologically distinct types of cells were identified in A. sculptum females via TEM: prohemocytes, plasmatocytes, granulocytes, and spherulocytes. In the reproductive efficiency analysis, 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. However, the results with novaluron did not show significant changes, with the highest concentration achieving an efficacy of 11.4%. After analyzing the cellular response, it was found that fluazuron significantly reduced 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, but at 24h, it significantly increased prohemocytes at concentrations of 10000 and 40000 μg.mL^-1, and at 48h it increased plasmatocytes and decreased granulocytes at concentrations of 10000 and 40000 μg.mL^-1. In TEM, both insect growth disruptors were able to promote ultrastructural morphological changes in the phagocytic hemocytes of A. sculptum. It is concluded that TEM allowed the characterization of four cell types in A. sculptum: prohemocytes, plasmatocytes, granulocytes, and spherulocytes. Furthermore, fluazuron and novaluron were able to promote cellular changes in the hemolymph of engorged females of A. sculptum after in vitro exposure. This is the first study to investigate the ultrastructural characteristics of hemocytes in female ticks of A. sculptum.

COMMITTEE MEMBERS:
Interna - ***.630.647-** - BARBARA RAUTA DE AVELAR - UFRRJ
Presidente - 1173660 - FABIO BARBOUR SCOTT
Externa à Instituição - JÉSSICA FIOROTTI DE PAULO
Interna - 2221855 - PATRICIA SILVA GOLO
Interna - 2929889 - THAIS RIBEIRO CORREIA AZEVEDO