scholarly journals Distribution of mitochondria in reconstructed mouse oocytes

Reproduction ◽  
2004 ◽  
Vol 127 (2) ◽  
pp. 195-200 ◽  
Author(s):  
Helena Fulka
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Germinal Vesicle ◽  
Model Experiments ◽  
Mouse Oocytes ◽  
Immature Mouse ◽  
Cycle Dependent

It has been suggested that nucleus replacement (transfer) may be used as an efficient oocyte therapy in order to prevent transmission of mutated mitochondrial DNA from mother to offspring in humans. The essential and not yet answered question is how mitochondria surrounding the karyoplast will be distributed in the newly reconstructed oocytes. In our model experiments, we have evaluated the distribution of mitochondria in reconstructed immature mouse oocytes when germinal vesicle karyoplasts, with labeled mitochondria, were fused to unlabeled cytoplasts. The penetration of mitochondria from karyoplasts into cytoplasts can be detected almost immediately after the beginning of fusion. In immature reconstructed oocytes, mitochondria are first located in the oocyte center but they are homogenously distributed within the whole cytoplasm before the completion of maturation. Fusion of oocytes at different stages of maturation suggests that the speed of mitochondria distribution is cell cycle dependent.

Induction of DNA replication in germinal vesicles and in nuclei formed in maturing mouse oocytes by 6-DMAP treatment

Zygote ◽  
1997 ◽  
Vol 5 (3) ◽  
pp. 213-217 ◽  
Author(s):  
J. Fulka ◽  
N.L. First ◽  
C. Lee ◽  
J. Fulka ◽  
R.M. Moor
Keyword(s):  
Dna Replication ◽  
Dna Synthesis ◽  
Germinal Vesicle ◽  
The Other ◽  
Immature Oocytes ◽  
Mouse Oocytes ◽  
Germinal Vesicles ◽  
Immature Mouse ◽  
Condensed Dna ◽  
Metaphase Ii Oocytes

SummaryImmature mouse oocytes (germinal vesicle stage, GV), oocytes at different stages during maturation (prometaphase to anaphase I) and matured oocytes (metaphase II arrested) were cultured in 6-dimethylaminopurine (6-DMAP)-supplemented medium also containing bromodeoxyuridine for the assessment of DNA replication in these cells. Immature oocytes remained arrested at the GV stage and DNA replication was never detected in them. On the other hand, oocytes at the prometaphase to anaphase-telophase I stages responded to 6-DMAP treatment by forming nuclei which synthesised DNA. Mature (metaphase II) oocytes did not respond to 6-DMAP and their chromatin remained condensed. DNA synthesis could even be induced in GV-staged oocytes, but only when they were fused to freshly activated oocytes and incubated in 6-DMAP-supplemented medium.

A direct measurement of increased divalent cation influx in fertilised mouse oocytes

Development ◽  
1996 ◽  
Vol 122 (7) ◽  
pp. 2199-2206 ◽  
Author(s):  
O.M. McGuinness ◽  
R.B. Moreton ◽  
M.H. Johnson ◽  
M.J. Berridge
Keyword(s):  
Cell Cycle ◽  
Dependent Manner ◽  
Continuous Increase ◽  
Mouse Oocytes ◽  
A Cell ◽  
Cycle Dependent ◽  
Precise Role ◽  
Entry Mechanism ◽  
Stimulation Of

On fertilisation of mouse oocytes, the fusing spermatozoon triggers a series of repetitive calcium (Ca2+) spikes. The Ca2+ spikes seem to be necessary for successful progression through the cell cycle and are regulated in a cell-cycle-dependent manner. The spikes appear to require the linkage of continuous Ca2+ influx to the periodic release of Ca2+ from intracellular stores by a process of Ca(2+)-induced Ca2+ release. The precise role of Ca2+ influx was explored using the manganese (Mn2+)-quench technique to monitor unidirectional cation influx into single mouse oocytes. There was a marked stimulation of cation influx associated closely with the upsweep of the first and subsequent fertilisation Ca2+ spikes. A smaller but significant increase in the rate of cation influx persisted in the interspike period in fertilised oocytes. Spike-associated entry was not as apparent in oocytes stimulated to spike repetitively by thimerosal or acetylcholine application. Instead, there was a continuous increase in cation influx underlying Ca2+ spiking which commenced with the onset of the first spike. Using the specific microsomal inhibitor thapsigargin and the Ca2+ ionophore ionomycin, we found evidence for a capacitative entry mechanism in mouse oocytes. We propose that the persistent influx of Ca2+ observed in response to all stimuli examined is controlled by a capacitative mechanism and sets the frequency of spiking by determining the time taken to refill the internal stores to a point where they are again sensitive enough to initiate the next spike.

Repetitive sperm-induced Ca2+ transients in mouse oocytes are cell cycle dependent

Development ◽  
1995 ◽  
Vol 121 (10) ◽  
pp. 3259-3266 ◽  
Author(s):  
K.T. Jones ◽  
J. Carroll ◽  
J.A. Merriman ◽  
D.G. Whittingham ◽  
T. Kono
Keyword(s):  
Cell Cycle ◽  
Nuclear Envelope ◽  
Dependent Manner ◽  
Nuclear Envelope Breakdown ◽  
Mouse Oocytes ◽  
A Cell ◽  
Mature Mouse ◽  
Cycle Dependent ◽  
Stage 1

Mature mouse oocytes are arrested at metaphase of the second meiotic division. Completion of meiosis and a block to polyspermy is caused by a series of repetitive Ca2+ transients triggered by the sperm at fertilization. These Ca2+ transients have been widely reported to last for a number of hours but when, or why, they cease is not known. Here we show that Ca2+ transients cease during entry into interphase, at the time when pronuclei are forming. In fertilized oocytes arrested at metaphase using colcemid, Ca2+ transients continued for as long as measurements were made, up to 18 hours after fertilization. Therefore sperm is able to induce Ca2+ transients during metaphase but not during interphase. In addition metaphase II oocytes, but not pronuclear stage 1-cell embryos showed highly repetitive Ca2+ oscillations in response to microinjection of inositol trisphosphate. This was explored further by treating in vitro maturing oocytes at metaphase I for 4–5 hours with cycloheximide, which induced nuclear progression to interphase (nucleus formation) and subsequent re-entry to metaphase (nuclear envelope breakdown). Fertilization of cycloheximide-treated oocytes revealed that continuous Ca2+ oscillations in response to sperm were observed after nuclear envelope breakdown but not during interphase. However interphase oocytes were able to generate Ca2+ transients in response to thimerosal. This data suggests that the ability of the sperm to trigger repetitive Ca2+ transients in oocytes is modulated in a cell cycle-dependent manner.

scholarly journals Cell Cycle-Dependent Localization and Properties of a Second Mitochondrial DNA Ligase in Crithidia fasciculata

2006 ◽  
Vol 5 (1) ◽  
pp. 54-61 ◽  
Author(s):  
Krishna Murari Sinha ◽  
Jane C. Hines ◽  
Dan S. Ray
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Mrna Level ◽  
Dna Ligase ◽  
Mitochondrial Matrix ◽  
Transcript Levels ◽  
Crithidia Fasciculata ◽  
Single Nucleus ◽  
Cycle Dependent ◽  
High Level

ABSTRACT The mitochondrial DNA in kinetoplastid protozoa is contained in a single highly condensed structure consisting of thousands of minicircles and approximately 25 maxicircles. The disk-shaped structure is termed kinetoplast DNA (kDNA) and is located in the mitochondrial matrix near the basal body. We have previously identified a mitochondrial DNA ligase (LIG kβ) in the trypanosomatid Crithidia fasciculata that localizes to antipodal sites flanking the kDNA disk where several other replication proteins are localized. We describe here a second mitochondrial DNA ligase (LIG kα). LIG kα localizes to the kinetoplast primarily in cells that have completed mitosis and contain either a dividing kinetoplast or two newly divided kinetoplasts. Essentially all dividing or newly divided kinetoplasts show localization of LIG kα. The ligase is present on both faces of the kDNA disk and at a high level in the kinetoflagellar zone of the mitochondrial matrix. Cells containing a single nucleus show localization of the LIG kα to the kDNA but at a much lower frequency. The mRNA level of LIG kα varies during the cell cycle out of phase with that of LIG kβ. LIG kα transcript levels are maximal during the phase when cells contain two nuclei, whereas LIG kβ transcript levels are maximal during S phase. The LIG kα protein decays with a half-life of 100 min in the absence of protein synthesis. The periodic expression of the LIG kα transcript and the instability of the LIG kα protein suggest a possible role of the ligase in regulating minicircle replication.

scholarly journals Active maturation-promoting factor is present in mature mouse oocytes.

1985 ◽  
Vol 100 (5) ◽  
pp. 1637-1640 ◽  
Author(s):  
R A Sorensen ◽  
M S Cyert ◽  
R A Pedersen
Keyword(s):  
Xenopus Oocytes ◽  
Germinal Vesicle ◽  
Xenopus Laevis Oocytes ◽  
Factor Activity ◽  
Dibutyryl Cyclic Amp ◽  
Germinal Vesicle Breakdown ◽  
Mouse Oocytes ◽  
Immature Mouse ◽  
Mature Mouse ◽  
Maturation Promoting Factor

Cytoplasmic extracts of meiotically mature mouse oocytes were injected into immature Xenopus laevis oocytes, which underwent germinal vesicle breakdown within 2 h. Germinal vesicle breakdown was not inhibited by incubation of the Xenopus oocytes in cycloheximide (20 micrograms/ml). Identically prepared extracts of meiotically immature mouse oocytes, arrested at the germinal vesicle stage by dibutyryl cyclic AMP (100 micrograms/ml), did not induce germinal vesicle breakdown in Xenopus oocytes. The results show that maturation-promoting factor activity appears during the course of oocyte maturation in the mouse.

scholarly journals Cell cycle localization dynamics of mitochondrial DNA polymerase IC in African trypanosomes

2018 ◽  
Vol 29 (21) ◽  
pp. 2540-2552 ◽  
Author(s):  
Jeniffer Concepción-Acevedo ◽  
Jonathan C. Miller ◽  
Michael J. Boucher ◽  
Michele M. Klingbeil
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Dna Polymerase ◽  
Dna Polymerases ◽  
Dynamic Environment ◽  
African Trypanosomes ◽  
Protein Levels ◽  
Replication Sites ◽  
Cycle Dependent ◽  
Mitochondrial Dna Polymerase

Trypanosoma brucei has a unique catenated mitochondrial DNA (mtDNA) network called kinetoplast DNA (kDNA). Replication of kDNA occurs once per cell cycle in near synchrony with nuclear S phase and requires the coordination of many proteins. Among these are three essential DNA polymerases (TbPOLIB, IC, and ID). Localization dynamics of these proteins with respect to kDNA replication stages and how they coordinate their functions during replication are not well understood. We previously demonstrated that TbPOLID undergoes dynamic localization changes that are coupled to kDNA replication events. Here, we report the localization of TbPOLIC, a second essential DNA polymerase, and demonstrate the accumulation of TbPOLIC foci at active kDNA replication sites (antipodal sites) during stage II of the kDNA duplication cycle. While TbPOLIC was undetectable by immunofluorescence during other cell cycle stages, steady-state protein levels measured by Western blot remained constant. TbPOLIC foci colocalized with the fraction of TbPOLID that localized to the antipodal sites. However, the partial colocalization of the two essential DNA polymerases suggests a highly dynamic environment at the antipodal sites to coordinate the trafficking of replication proteins during kDNA synthesis. These data indicate that cell cycle–dependent localization is a major regulatory mechanism for essential mtDNA polymerases during kDNA replication.

Germinal Vesicle Transfer Between Fresh and Cryopreserved Immature Mouse Oocytes

2000 ◽  
Vol 74 (3) ◽  
pp. S47-S48
Author(s):  
F Comoglio ◽  
F Moffa ◽  
H Liu ◽  
J.A Grifo ◽  
L.C Krey ◽  
...  
Keyword(s):  
Germinal Vesicle ◽  
Mouse Oocytes ◽  
Immature Mouse

scholarly journals YWHA (14-3-3) protein isoforms and their interactions with CDC25B phosphatase in mouse oogenesis and oocyte maturation

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Alaa A. Eisa ◽  
Santanu De ◽  
Ariana Detwiler ◽  
Eva Gilker ◽  
Alexander C. Ignatious ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Oocyte Maturation ◽  
Messenger Rna ◽  
Germinal Vesicle ◽  
Protein Isoforms ◽  
Cell Cycle Protein ◽  
Meiotic Arrest ◽  
Germinal Vesicle Breakdown ◽  
Prophase I ◽  
Mouse Oocytes

Abstract Background Immature mammalian oocytes are held arrested at prophase I of meiosis by an inhibitory phosphorylation of cyclin-dependent kinase 1 (CDK1). Release from this meiotic arrest and germinal vesicle breakdown is dependent on dephosphorylation of CDK1 by the protein, cell cycle division 25B (CDC25B). Evidence suggests that phosphorylated CDC25B is bound to YWHA (14-3-3) proteins in the cytoplasm of immature oocytes and is thus maintained in an inactive form. The importance of YWHA in meiosis demands additional studies. Results Messenger RNA for multiple isoforms of the YWHA protein family was detected in mouse oocytes and eggs. All seven mammalian YWHA isoforms previously reported to be expressed in mouse oocytes, were found to interact with CDC25B as evidenced by in situ proximity ligation assays. Interaction of YWHAH with CDC25B was indicated by Förster Resonance Energy Transfer (FRET) microscopy. Intracytoplasmic microinjection of oocytes with R18, a known, synthetic, non-isoform-specific, YWHA-blocking peptide promoted germinal vesicle breakdown. This suggests that inhibiting the interactions between YWHA proteins and their binding partners releases the oocyte from meiotic arrest. Microinjection of isoform-specific, translation-blocking morpholino oligonucleotides to knockdown or downregulate YWHA protein synthesis in oocytes suggested a role for a specific YWHA isoform in maintaining the meiotic arrest. More definitively however, and in contrast to the knockdown experiments, oocyte-specific and global deletion of two isoforms of YWHA, YWHAH (14-3-3 eta) or YWHAE (14-3-3 epsilon) indicated that the complete absence of either or both isoforms does not alter oocyte development and release from the meiotic prophase I arrest. Conclusions Multiple isoforms of the YWHA protein are expressed in mouse oocytes and eggs and interact with the cell cycle protein CDC25B, but YWHAH and YWHAE isoforms are not essential for normal mouse oocyte maturation, fertilization and early embryonic development.

Cell cycle dependent morphology changes and associated mitochondrial DNA redistribution in mitochondria of human cell lines

Mitochondrion ◽  
2002 ◽  
Vol 1 (5) ◽  
pp. 425-435 ◽  
Author(s):  
Daciana H Margineantu ◽  
W Gregory Cox ◽  
Linda Sundell ◽  
Steven W Sherwood ◽  
Joseph M Beechem ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Mitochondrial Dna ◽  
Cell Lines ◽  
Human Cell ◽  
Human Cell Lines ◽  
Cycle Dependent ◽  
Morphology Changes
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