No abstract

Known as a degenerative joint disorder of advanced age affecting predominantly females, osteoarthritis can develop in younger and actively working people because of activities involving loading and injuries of joints. Collagenase-induced osteoarthritis (CIOA) in a mouse model allowed us to investigate for the first time its effects on key cytoskeletal structures (meiotic spindles and actin distribution) of ovulated mouse oocytes. Their meiotic spindles, actin caps, and chromatin were analyzed by immunofluorescence. A total of 193 oocytes from mice with CIOA and 209 from control animals were obtained, almost all in metaphase I (M I) or metaphase II (MII). The maturation rate was lower in CIOA (26.42% M II) than in controls (55.50% M II). CIOA oocytes had significantly larger spindles (average 37 μm versus 25 μm in controls, p < 0.001 ), with a proportion of large spindles more than 64% in CIOA versus up to 15% in controls ( p < 0.001 ). Meiotic spindles were wider in 68.35% M I and 54.90% M II of CIOA oocytes (mean 18.04 μm M I and 17.34 μm M II versus controls: 11.64 μm M I and 12.64 μm M II), and their poles were approximately two times broader (mean 6.9 μm) in CIOA than in controls (3.6 μm). CIOA oocytes often contained disoriented microtubules. Actin cap was visible in over 91% of controls and less than 20% of CIOA oocytes. Many CIOA oocytes without an actin cap had a nonpolarized thick peripheral actin ring (61.87% of M I and 52.94% of M II). Chromosome alignment was normal in more than 82% in both groups. In conclusion, CIOA affects the cytoskeleton of ovulated mouse oocytes—meiotic spindles are longer and wider, their poles are broader and with disorganized fibers, and the actin cap is replaced by a broad nonpolarized ring. Nevertheless, meiotic spindles were successfully formed in CIOA oocytes and, even when abnormal, allowed correct alignment of chromosomes.

The effects of prostaglandin F2α on the cytoskeleton and membrane organelles of oocytes was investigated by culturing ovulated mouse oocytes in its presence (50 or 100 ng/ml) for 3 h. Tubulin, fibrillar actin, membranes and chromatin were visualized by specific antibodies, phalloidin, lipophilic dye DiOC6 and Hoechst 33342, respectively. Control oocytes were characterized by a meiotic spindle with chromosomes aligned at its equator, and a cortical layer of microfilaments with an actin cap. Intracellular membranes were localized mostly in the central region in metaphase I and in a broader volume, but still excluding the cell periphery, in metaphase II, and were slightly concentrated around the chromosomes. In oocytes treated with 50 ng/ml prostaglandin, cortical actin staining was diminished, the membrane distribution was clustered, and chromosomes showed signs of misalignment despite the apparently preserved spindle. In cells treated with 100 ng/ml prostaglandin, both the spindle and the actin cortex had degenerated or disappeared as microscopic objects. Metaphase plates were on average broader and more disorganized than in the 50 ng/ml group, and the distribution of membrane organelles had become uniform. These effects, to our knowledge observed for the first time, did not require presence of the cumulus during the incubation. They could be regarded as acceleration of the oocyte postovulatory aging, in which cytoskeletal deterioration seemed to have a leading role.

SummaryThe tubulin cytoskeleton is vital for maintenance and dynamics of eukaryotic cells and molecular defects in its components can lead to serious conditions. So far, mutations in genes for alpha-, beta- and gamma-tubulin, motor proteins of the kinesin and dynein family, microtubule-associated and centrosomal proteins have been found to cause disorders in humans. Most phenotypic effects are on the nervous system, leading to abnormal brain development (e.g. lissencephaly and microcephaly) or to neurodegeneration in later life (e.g. amyotrophic lateral sclerosis and frontotemporal dementia). Another group of disorders include the ciliopathies, caused by defects in the axoneme. They include primary ciliary dyskinesia (immotile cilia syndrome), which is characterized by chronic respiratory infections, male infertility and randomly established left-right asymmetry. In most cases, the underlying defects are in axonemal dynein. Mutations in genes for centrosomal components have been shown to cause cortical dysplasia and dwarfism by disrupting the mitotic spindle, and some cases of infertility with maturation arrest are likely to be caused by unidentified mutations damaging the meiotic spindle. In view of these diverse phenotypes, knowledge about mutations affecting tubulin cytoskeleton becomes increasingly useful for clinical practice.

SummaryThe reaction of anti-sperm antibody-positive sera from infertile women with fractionated mouse ovarian antigens was measured by enzyme-linked immunosorbent assay (ELISA). Antigens were obtained by extraction for nuclear matrix and intermediate laments (NM-IF) producing three protein fractions -soluble, cytoskeletal and NM-IF. The results showed that sera from some infertile patients, but not control sera, react with either the soluble fraction or the NM-IF fraction. The reaction with soluble proteins was most likely directed against surface antigens, possibly aggravating the fertility problems, while the anti-NM-IF antibodies could indicate release of insoluble intracellular components by tissue damage of unknown origin.

In eukaryotic cells during interphase, the centrosome is positioned close to the nucleus by a yet unidentified mechanism and determines the basic cell polarity. The aim of this study was to trace the dynamics of centriolar satellite protein PCM-1 in newborn mouse ovaria. Ovarian sections of newborn mice were subjected to immunofluorescent analysis. The intracellular localization of PCM-1 in prophase I oocytes was compared between 1-and 2-day-old mice. In oocytes from 1-day-old ovaria, double or broader single discrete PCM-1 aggregates with perinuclear localization were observed in association with condensed chromatin regions. In oocytes from 2-day-old ovaria, PCM-1 structures were less discrete and chromatin was homogenous. In some oocytes, single or double PCM-1 aggregate was still recognizable, while in others, the PCM-1-containing structure was crescent-shaped. Our study describes for the first time reorganization of centriolar satellite protein PCM-1 in prophase I oocytes from developing primordial follicles correlated with chromatin changes during transition to dictyate.