Mitochondrial behavior during oogenesis in zebrafish: A confocal microscopy analysis

Abstract

The behavior of mitochondria during early oogenesis remains largely unknown in zebrafish. We used three mitochondrial probes (Mito Tracker Red CMXRos, Mito Tracker Green FM, and JC-1) to stain early zebrafish oocyte mitochondria, and confocal microscopy to analyze mitochondrial aggregation and distribution. By using fluorescence recovery after photobleaching (FRAP), we traced mitochondrial movement. The microtubule assembly inhibitor nocodazole and microfilament inhibitor cytochalasin B (CB) were used to analyze the role of microtubules and microfilaments on mitochondrial movement. By using the dual emission probe, JC-1, and oxidative phosphorylation uncoupler, carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP), we determined the distribution of active and inactive (low-active) mitochondria. Green/red fluorescence ratios of different sublocations in different oocyte groups stained by JC-1 were detected in merged (green and red) images. Our results showed that mitochondria exhibited a unique distribution pattern in early zebrafish oocytes. They tended to aggregate into large clusters in early stage I oocytes, but in a threadlike state in latter stage I oocytes. We detected a lower density mitochondrial area and a higher density mitochondrial area on opposite sides of the germinal vesicle. The green/red fluorescence ratios in different sublocations in normal oocytes were about 1:1. This implies that active mitochondria were distributed in all sublocations. FCCP treatment caused significant increases in the ratios. CB and nocodazole treatment caused an increase of the ratios in clusters and mitochondrial cloud, but not in dispersed areas. Mitochondria in different sublocations underwent fast dynamic movement. Inhibition or disruption of microtubules or microfilaments resulted in even faster mitochondrial free movement.

Mitochondrial behaviors in the vitrified mouse oocyte and its parthenogenetic embryo: effect of Taxol pretreatment and relationship to competence

“…The dynamic movement of mitochondria in fresh oocytes in our experiment is consistent with observations made in zebrafish oocytes, in which microtubules depolymerized with nocodazole led to even faster mitochondrial movement (31). In our work, Taxol pretreatment slowed mitochondria movement, and vitrification made it more rapid (see Figs.…”

Transmission of Mitochondrial DNA Diseases and Ways to Prevent Them

“…The Balbiani body comprises mitochondria and endoplasmic reticulum organized around Golgi elements [73]–[78] that may enable germplasm mRNAs to be specifically inherited by the PGCs in the future embryo. In the same way, a specific mitochondrial sub-population may segregate to the Balbiani bodies and ultimately populate the PGCs [73], [79]–[81], potentially explaining the pattern of selection against severe mtDNA mutations.…”

“…In the same way, a specific mitochondrial sub-population may segregate to the Balbiani bodies and ultimately populate the PGCs [73], [79]–[81], potentially explaining the pattern of selection against severe mtDNA mutations. In some non-mammalian species mitochondria with the highest membrane potentials are found in Balbiani bodies [78], [80], [81], suggesting that high-quality mitochondria and mtDNAs are selected for transmission to the PGCs of the next generation. While this is an appealing mechanism for selecting against mutant mtDNAs, there is little supporting evidence and it is still controversial, even in mouse [52].…”

Mutation of zebrafish dihydrolipoamide branched-chain transacylase E2 results in motor dysfunction and models maple syrup urine disease

“…Throughout the first 5 days of zebrafish development, the embryo consumes the presumptive equivalent of a high-protein diet in mammals by absorbing BCAA-containing proteins from the yolk (Link et al, 2006; Tay et al, 2006). During the earliest stages of development, within the first few hours post-fertilization, the metabolic needs of the embryo are largely met by maternally derived mitochondria and mRNA (Mendelsohn and Gitlin, 2008; Zhang et al, 2008; Abrams and Mullins, 2009). However, as embryogenesis proceeds, BCAA metabolism increasingly relies upon zygotic transcription.…”