title: Microscopic and molecular characterization of ovarian follicle atresia in Rhodnius prolixus Stahl under immune challenge.
abstract: In this work we characterized the degenerative process of ovarian follicles of the bug Rhodnius prolixus challenged with the non-entomopathogenic fungus Aspergillus niger. An injection of A. niger conidia directly into the hemocoel of adult R. prolixus females at the onset of vitellogenesis caused no effect on host lifespan but elicited a net reduction in egg batch size. Direct inspection of ovaries from the mycosed insects revealed that fungal challenge led to atresia of the vitellogenic follicles. Light microscopy and DAPI staining showed follicle shrinkage, ooplasm alteration and disorganization of the monolayer of follicle cells in the atretic follicles. Transmission electron microscopy of thin sections of follicle epithelium also showed nuclei with condensed chromatin, electron dense mitochondria and large autophagic vacuoles. Occurrence of apoptosis of follicle cells in these follicles was visualized by TUNEL labeling. Resorption of the yolk involved an increase in protease activities (aspartyl and cysteinyl proteases) which were associated with precocious acidification of yolk granules and degradation of yolk protein content. The role of follicle atresia in nonspecific host-pathogen associations and the origin of protease activity that led to yolk resorption are discussed.
authors.affiliation: Programa de Biologia Celular e Parasitologia, Instituto de Biofísica Carlos Chagas Filho da UFRJ, Brazil.
authors.forename: Marcelo N
authors.initials: MN
authors.lastname: Medeiros
authors.forename: Isabela B
authors.initials: IB
authors.lastname: Ramos
authors.forename: Danielle M P
authors.initials: DM
authors.lastname: Oliveira
authors.forename: Rodrigo C B
authors.initials: RC
authors.lastname: da Silva
authors.forename: Fabio M
authors.initials: FM
authors.lastname: Gomes
authors.forename: Luciano N
authors.initials: LN
authors.lastname: Medeiros
authors.forename: Eleonora
authors.initials: E
authors.lastname: Kurtenbach
authors.forename: Luciana B
authors.initials: LB
authors.lastname: Chiarini
authors.forename: Hatisaburo
authors.initials: H
authors.lastname: Masuda
authors.forename: Wanderley
authors.initials: W
authors.lastname: de Souza
authors.forename: Ednildo A
authors.initials: EA
authors.lastname: Machado
mesh_terms: D000818:Animals; D017209:Apoptosis; D057055:Aspartic Acid Proteases / Q000378:metabolism; D001234:Aspergillus niger / Q000502:physiology*; D057056:Cysteine Proteases / Q000378:metabolism; D005260:Female; D005456:Fluorescent Dyes; D005496:Follicular Atresia; D020287:In Situ Nick-End Labeling; D007211:Indoles / Q000737:chemistry; D046529:Microscopy, Electron, Transmission; D012239:Rhodnius / Q000276:immunology* / Q000382:microbiology* / Q000502:physiology; D014818:Vitellogenesis
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; C007293:DAPI; D057055:Aspartic Acid Proteases; D057056:Cysteine Proteases