The expression of estrogen receptors during the Mytilus galloprovincialis ovarian cycle

Abstract

The aim of this paper is to assess, by real‐time polymerase chain reaction and in situ hybridization, the expression of estrogen receptors ER1 and ER2 during the ovarian cycle of Mytilus galloprovincialis. By considering four phases of the reproductive cycle, that is stasis and previtellogenic stage (Stage 0), early vitellogenesis (Stage I), vitellogenesis (Stage II), full‐grown oocyte (Stage III), our investigation demonstrates that the two receptors are differently expressed during the phases investigated of the ovarian cycle: ER1 reaches the highest level at Stage III, whereas ER2 reaches the highest level at Stage II, with ER2 always present at higher levels than ER1. The stage‐dependent receptor expression was recorded within oocytes, follicle cells, and adipogranular cells. No ER1 and ER2 messenger RNAs (mRNAs) were found within vesicular cells. It is to be noted that the ER1 and ER2 expression within the growing oocytes, the follicular, and adipogranular cells overlaps with that of the mRNA for vitellogenin in the same cells, strongly suggesting that in Mytilus, as in vertebrates studied so far, the vitellogenin expression is under the control of estrogens.

Sex and gametogenesis stage are strong drivers of gene expression in Mytilus edulis exposed to environmentally relevant plasticiser levels and pH 7.7

“…Natural variation in the oestrogen receptor-like physiological conditions could be based on annual and seasonal contexts, as already noted for M. edulis MeER2 expression (Ciocan et al 2010). Similarly, variable expression of oestrogen receptor-like genes was found during M. galloprovincialis ovarian cycle (Agnese et al 2019) and throughout larval development (Balbi et al 2016). In this case, the initial hypothesis of this experiment that the action of certain stressors could be affected by the reproductive cycle did not find confirmation, as we found no significant influence by the gametogenesis stage on the gene expression of oestrogen receptor-like response.…”

Long-term exposure of marine mussels to paracetamol: is time a healer or a killer?

“…The long-term exposure data suggest similar levels of downregulation regardless of the sex of mussels and paracetamol concentration and thus a more widespread effect. Several studies have documented the expression of estrogen receptors in different invertebrates (Keay and Thornton 2009;Jones et al 2017), in addition to mussels (Puinean et al 2006;Agnese et al 2019;Balbi et al 2019). However, it is also worth considering that ER2 might display natural variation during different stages of gametogenesis (Ciocan et al 2010); hence, further investigation is required.…”

Long term exposure of marine mussels to paracetamol: is time a healer or a killer?

“…The long term exposure data suggest similar levels of downregulation regardless of the sex of mussels and paracetamol concentration, thus a more widespread effect. Several studies have documented the expression of estrogen receptors in different invertebrates (Keay and Thornton, 2009;Jones et al, 2017), in addition to mussels (Puinean et al, 2006;Agnese et al, 2019;Balbi et al, 2019). However, it is also worth considering that ER2 might display natural variation during different stages of gametogenesis (Ciocan et al, 2010), hence further investigation is required.…”