Banca de DEFESA: DAYANA PALMEIRA DA SILVA ROSA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : DAYANA PALMEIRA DA SILVA ROSA
DATE: 31/08/2022
TIME: 13:45
LOCAL: meet.google.com/goh-ijrj-gob
TITLE:

Stomoxys calcitrans: characterization of circulating hemocytes and first identification of Herpetomonas muscarum, with evaluation of their interaction aspects

 

KEY WORDS:

mechanical vectors, immune system, monoxenic trypanosomatids

PAGES: 91
BIG AREA: Ciências Biológicas
AREA: Parasitologia
SUBÁREA: Entomologia e Malacologia de Parasitos e Vetores
SUMMARY:

Stomoxys calcitrans is a cosmopolitan and hematophagous dipteran. Its feeding habit is defined as aggressive and persistent, having different warm-blooded species as hosts. It is considered a pest of economic importance to cattle and other animals, causing reduction of the weight and milk production in livestock. In rearing environments, members of the genus Stomoxys play an important role in the epidemiology of transmissible diseases, being mechanical vectors of several pathogens. Knowing and understanding the cellular components of the fly's immune system and the relationship between the S. calcitrans organism and the pathogens it transmits is essential to clarify the pathways involved in these interactions, identifying the best research targets for the development of control techniques for this livestock pest. Thus, in this work we isolated and quantified the number of circulating hemocytes in different evolutionary phases of the fly, identifying larger populations in the evaluated field individuals. From the isolation, we were able to identify and characterize these hemocytes in four types, namely: prohemocytes, granulocytes, plasmatocytes and oenocytoids. Prohemocytes were in the lower number of cells in the assays, and plasmatocytes were the most abundant cells. Responding to an experimental infection by Herpetomonas muscarum, the time of greatest hemocytic response ocurred at  two hours after the injection of trypanosomatid. In general, the populations of different types of hemocytes increased after infection, with the exception of prohemocytes, which decreased. The production of extracellualr traps (ETs) by S. calcitrans stimulated with LPS was also evaluated, being possible to identify the release of DNA after stimulation. We identified the presence of a parasite in the hemolymph of S. calcitrans in individuals from the field, larvae in the laboratory and adults generated in a colony. It was isolated and identified at the species level by DNA sequencing, being the trypanosomatid called H. muscarum. To evaluate its interaction aspects with its host, we initially performed its growth curve to understand its development and identify the best times for laboratory tests. The interaction of this parasite was analyzed at the intestinal level, by in vivo and in vitro experiments, demonstrating that it is able to interact and settle in the intestine even after a few hours of interaction. Finally, we evaluated developmental aspects of the stable fly infected orally with H. muscarum. The longevity of individuals was not significantly altered, as well as their oviposition. However, the viability of the eggs was affected, thus reducing their hatching and, consequently, impairing the development of larvae in pupae and pupae in adult individuals. Thus, the reproduction of S. calcitrans is affected when it is infected by H. muscarum. More evaluations should be carried out, for a better understanding of the hemocytic reactions of S. calcitrans, but this work already elucidates the types of hemocytes present in its circulation and methods of their extraction. The interactions of the fly with the trypanosomatid reveal a potential use in two aspects, namely: (1) use of the trypanosomatid for controlling the population of S. calcitrans; (2) use of these organisms as an experimental model for understanding the relationship between dipterans and the trypanosomatids that infect them, through laboratory tests.

BANKING MEMBERS:
Presidente - 1792175 - PATRICIA FAMPA NEGREIROS LIMA
Interna - 3103528 - CLAUDIA BEZERRA DA SILVA
Externa ao Programa - 3145590 - DANIELA COSENTINO GOMES - UFRRJExterno ao Programa - 1109555 - JAIRO PINHEIRO DA SILVA - UFRRJExterna à Instituição - DANIELE PEREIRA DE CASTRO - FIOCRUZ
Externa à Instituição - ANGELA HAMPSHIRE LOPES - UFRJ
Externa à Instituição - EVELIZE FOLLY DAS CHAGAS - UFF