Analysis of the Behavior of Mitochondria in the Ovaries of the Earthworm Dendrobaena veneta Rosa 1839

Abstract

We examined six types of cells that form the ovary of the earthworm Dendrobena veneta ogonia, prooocytes, vitellogenic oocytes, trophocytes, fully grown postvitellogenic oocytes and somatic cells of the gonad. The quantitative stereological method revealed a much higher “volume density” of mitochondria in all of the types of germ-line cells except for the somatic cells. Fluorescent vital stain JC-1, however, showed a much higher oxidative activity of mitochondria in the somatic cells than in the germ-line cells. The distribution of active and inactive mitochondria within the studied cells was assessed using the computer program ImageJ. The analysis showed a higher luminosity of inactive mitochondria in all of the types of germ-line cells and a higher luminosity of active mitochondria in somatic cells. The OXPHOS activity was found in somatic cells mitochondria and in the peripheral mitochondria of the vitellogenic oocytes. The detection of reactive oxygen species (ROS) revealed a differentiated distribution of ROS in the different cell types. The amount of ROS substances was lower in somatic cells than in younger germ-line cells. The ROS level was also low in the cytoplasm of fully grown postwitellogenic oocytes. The distribution of the MnSOD enzyme that protects mitochondria against destructive role of ROS substances was high in the oogonia and in prooocytes and it was very high in vitellogenic and postvitellogenic oocytes. However, a much lower level of this protective enzyme was observed in the trophocytes and the lowest level was found in the cytoplasm of somatic cells. The lower mitochondrial activity and higher level of MnSOD activity in germ-line cells when compared to somatic cells testifies to the necessity of the organisms to protect the mitochondria of oocytes against the destructive role of the ROS that are produced during oxidative phosphorylation. The protection of the mitochondria in oocytes is essential for the transfer of healthy organelles to the next generation.

Peer Review #1 of "Relationship between ROS production, MnSOD activation and periods of fasting and re-feeding in freshwater shrimp Neocaridina davidi (Crustacea, Malacostraca) (v0.1)"

“…Mitochondria are organelles which participate not only in ATP production, but also in synthesis of ROS, antioxidative enzymes, cell death activation, etc. (Fernandez-Checa, 2003;Faron et al, 2015;Małota et al, 2019).…”

“…The first signal of changes appearing in the mitochondria is the alteration in the transmembrane mitochondrial potential (ΔCm) (Faron et al, 2015;Sonakowska et al 2016). Ultrastructural alterations together with transmembrane potential (ΔCm) may be connected with the activation of cell death (Sonakowska et al, 2016).…”

“…This may indicate an increase in electron leakage while reducing the mitochondrial membrane potential. Thus, increasing the production of free radicals does not have to be associated with greater mitochondrial activity (Speakman et al, 2004;Faron et al, 2015). Manuscript to be reviewed increase in the level of ROS causes the beginning of proliferation, differentiation or even cell death.…”

“…synthesis of ATP and reactive oxygen species (ROS), or activation of cell death (Martin, 2010;Kamogashira et al, 2015;Włodarczyk et al, 2019). Ultrastructural alterations of mitochondria (Fernandez-Checa, 2003;Faron et al, 2015;Włodarczyk et al, 2017) also cause changes in the functioning of the enzyme system. In several places along the mitochondrial respiratory chain (mainly due to complexes I and III), electrons can react directly with oxygen or another electron acceptor and generate free radicals.…”

“…Manuscript to be reviewed Zhang et al 2007;Combelles et al, 2009;Umasuthan et al 2012;Faron et al, 2015).…”