Ovarian regression and apoptosis in the South American teleost Leporinus taeniatus Lütken (Characiformes, Anostomidae) from the São Francisco Basin

Abstract

Involution and resorption of both postovulatory and atretic follicles were analysed in piau-jejo Leporinus taeniatus (Characiformes, Anostomidae) in order to evaluate the role of apoptosis during ovarian regression. Histological and ultrastructural analyses showed hallmarks of apoptosis in the granulosa: aggregation of compacted chromatin against the nuclear envelope, cell shrinkage, surface blebbing, loss of cell adhesion and cell fragmentation into apoptotic bodies. Protein synthesis activity preceded the onset of the cell death. The breakdown of the basement membrane led to the detachment of the granulosa cells into the follicular lumen. TUNEL-positive reactions were detected in in situ DNA fragmentation of granulosa of both postovulatory and atretic follicles. Apoptosis increased in a time-dependent manner contributing to reduction of the follicular areas. The apoptotic index (per cent of apoptotic cells) of the granulosa increased in postovulatory follicles soon after spawning, then these follicles degenerated and only remnants were observed at 7 days. In contrast, the granulosa cells reabsorbed the yolk during follicular atresia and the apoptotic index increased only in the late stage of regression. The results indicated apoptosis as the major mechanism to rapidly eliminate postovulatory follicles and being an essential process in the ovarian regression after spawning. # 2005 The Fisheries Society of the British Isles

Relationship among follicular apoptosis, integrin β1 and collagen type IV during early ovarian regression in the teleost Prochilodus argenteus after induced spawning

“…However, during follicular regression, they exhibit the loss of cell-cell and cell-extracellular matrix attachment. These pro-apoptotic events have also been observed in Astyanax bimaculatus lacustris and Leporinus taeniatus (Drummond et al 2000;Santos et al 2005). Healthy follicular cells with intense phagocytic activity have been detected in P. argenteus and in postovulatory follicles of other teleosts.…”

“…The follicular area (F A ) was measured by using software for digital image analyses, viz., Kontron KS 400 (Carl Zeiss Vision, Germany). The apoptotic index (I A =100C A C −1 , where C A is the number of apoptotic cells, and C is the total number of cells) was determined for the follicular cells according to Santos et al (2005). The mean I A and F A values were calculated by using 60 postovulatory follicles at each time interval from recently spawned ovaries up to 5 days post-spawning.…”

“…In teleosts, apoptosis is important in the selection and recruitment of follicles for vitellogenesis and in ovarian regression after spawning (Drummond et al 2000;Van Der Kraak 2001, 2002;Santos et al 2005;Thomé et al 2006). According to Piechotta et al (1999), apoptosis is a sensitive biomarker for the monitoring of environmental impact.…”

Guidelines for the use and interpretation of assays for monitoring autophagy

“…838 Assessment of autophagy in fish has been primarily made using TEM at different times of ovarian regression. 839 Due to the difficulty of obtaining antibodies specific for each fish species, immunodetection of ATG-proteins (mainly LC3 and BECN1) by immunohistochemistry associated with analyses by western blotting can be performed using antibodies that are commercially available for other vertebrates. Such studies suggest dual roles for autophagy in follicular cells; 836 however, evaluation of the autophagic flux in different conditions is critical for establishing its physiological role during follicular regression and ovarian remodeling after spawning.…”

The annual cycle of oogenesis in the shanny, <i>Lipophrys pholis</i> (Pisces: Blenniidae)

“…The presence of these follicles is not only an indicator of reproductive maturity and recent spawning events, but can also indicate adverse conditions such as an increase in stress due to changes in environment (Agostinho 2007). Because the mechanism that initiates and regulates oocyte re-absorption in teleosts is still poorly understood (Santos et al 2005), the phenomenon of atresia and its consequences in oocyte production is a major issue to be addressed in future studies.…”