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.

Long-chain acyl-CoA synthetase 2 knockdown leads to decreased fatty acid oxidation in fat body and reduced reproductive capacity in the insect Rhodnius prolixus

“…Opercula from oocytes and eggs were detached and the samples were fixed, post-fixed and dehydrated as described [36]. Samples were embedded in Polybed 812 resin and thin sections were contrasted with lead citrate and uranyl acetate, followed by observation in a Zeiss 900 transmission electron microscope (Carl Zeiss Microscopy, Jena, Germany) operating at 80 kV.…”

OVARIAN NUTRITIONAL RESOURCES DURING THE REPRODUCTIVE CYCLE OF THE HEMATOPHAGOUS DIPETALOGASTER MAXIMA (HEMIPTERA: REDUVIIDAE): FOCUS ON LIPID METABOLISM

“…The period of rapid oocyte growth and accumulation of yolk, vitellogenesis, is characterized by the extraovarian synthesis of yolk protein precursors that are taken up by the oocyte (Snigirevskaya and Raikhel, ). On the other hand, food deprivation as well as other unfavorable behavioral or environmental factors promote the degeneration of some follicles to an atretic stage and oocyte resorption (Bell and Bohm, ; Aguirre et al., ; Medeiros et al., ). Oocyte resorption (oosorption) is a reproductive strategy to preserve valuable resources to expand female lifespan and/or to secure its reproductive success (Bell and Bohm, ; Wang and Horng, ; Moore and Attisano, ).…”

The natural insect peptide Neb-colloostatin induces ovarian atresia and apoptosis in the mealworm Tenebrio molitor

“…In recent years, several control strategies have been proposed as species-specific and non-polluting methods for reducing or suppressing pest reproduction, especially insect–pathogen interactions or development of the sterile insect technique [31,32]. As previously reported [9], injection of Neb -colloostatin and Neb -TMOF into T. molitor females causes gonadoinhibitory effects on ovarian development, however, the mode of action of these peptides remains unknown.…”

“…However, follicular atresia has been massively induced in response to starvation, malfunction of ecdysone signalling or treatment with chemotherapeutic drugs [23,27-30]. Pathogen infection can also lead to atresia of the ovarian vitellogenic follicles as recently shown in Rodnius prolixus [31]. …”