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Sperm morphology and molecular mechanism associated with sperm fertilizing ability in mice.
Šebková, Nataša ; Komrsková, Kateřina (advisor) ; Jonáková, Věra (referee) ; Linhart, Otomar (referee)
The process of sperm capacitation and acrosome reaction (AR) are highly dynamic processes essential for the fertilization, including cytoskeleton proteins in the sperm head. The study of the distribution of actin, spectrin and α-tubulin in the head of representative mammalian sperm indicates that before and after the AR there were changes in the distribution of the cytoskeleton structures in the sperm head of all representatives, mainly in the apical part of the acrosome, but also in the equatorial and postacrosome part of the sperm head. The particularly well-studied actin cytoskeleton plays an important role during the capacitation and before and after the AR. Environmental estrogens can interfere with the function of endogenous hormones in very low concentrations. They can interact with specific receptors affecting several signalling pathways leading to sperm capacitation and AR. The effect of 17β-estradiol, estrone, estriol and synthetic 17α-ethynylestradiol was evaluated by the ratio of tyrosine phosphorylation and the state of the acrosome during in vitro capacitation in the sperm head. This study has provided the evidence that estrogens significantly stimulate capacitation progress in a concentration-dependent manner. Estrogens decrease number of sperm after the induced AR too. The raising...
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The role of centrobin in spermatogenesis
Flintová, Jennifer ; Komrsková, Kateřina (advisor) ; Šebková, Nataša (referee)
Spermatogenesis is a highly orchestrated, strictly regulated cascade of events that could be divided into three major processes: mitotic expansion of diploid germ cells (spermatocytogenesis), meiotic division creating haploid cells, and spermiogenesis. Spermiogenesis, the final stage of spermatogenesis comprises a striking metamorphosis of round haploid spermatids into morphologically and functionally specialized spermatozoa designed for the fertilization. One of the proteins indispensable for proper sperm morphogenesis is centrobin, a structural component of the specialized cytoskeletal structures of the elongating spermatids (acroplaxome and manchette), executing essential role in sperm head shaping and assembly of the head-tail coupling apparatus. Disruption in Cntrob gene (coding for centrobin) in rats homozygous at the hd (hypodactyly) locus results in male infertility, with a striking morphological signature called "decapitated sperm syndrome" with detachment of sperm head from the flagellum due to impaired head-tail coupling. However, molecular function of centrobin in spermiogenesis is still unknown. Sperm decapitation is a distinct phenotype described in several mouse mutants and importantly from infertile human males. Strikingly, in addition to proteins functioning in cytoskeletal...
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The involvement of mitotic kinases AURKA and PLK1 in the oocyte meiotic maturation
Brzáková, Adéla ; Šolc, Petr (advisor) ; Šebková, Nataša (referee)
Aurora A and Plk1 belongs to the extended family of serine/threonine kinases controlling the cell cycle. Both are involved in the control of mitosis and contribute also to the regulation of meiotic division. Although the role of Aurora A in the resumption of meiosis after the first meiotic block seems to be, according to present studies, a bit questionable matter, it is virtually certain that AURKA plays an irreplaceable role in the construction of the spindle. In the oocytes with inhibited (by RNAi or small molecular inhibitors) or overexpressed Aurora A, abnormal spindles with aberrant number of poles or otherwise unusually shaped spindles are created. Disruption of Plk1 function in oocytes also leads to the appearance of damaged spindles. In addition, Plk1, almost certainly, plays a role in the timing of the nuclear membrane breakdown - at GVBD.
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The role of centrobin in spermatogenesis
Flintová, Jennifer ; Komrsková, Kateřina (advisor) ; Šebková, Nataša (referee)
Spermatogenesis is a highly orchestrated, strictly regulated cascade of events that could be divided into three major processes: mitotic expansion of diploid germ cells (spermatocytogenesis), meiotic division creating haploid cells, and spermiogenesis. Spermiogenesis, the final stage of spermatogenesis comprises a striking metamorphosis of round haploid spermatids into morphologically and functionally specialized spermatozoa designed for the fertilization. One of the proteins indispensable for proper sperm morphogenesis is centrobin, a structural component of the specialized cytoskeletal structures of the elongating spermatids (acroplaxome and manchette), executing essential role in sperm head shaping and assembly of the head-tail coupling apparatus. Disruption in Cntrob gene (coding for centrobin) in rats homozygous at the hd (hypodactyly) locus results in male infertility, with a striking morphological signature called "decapitated sperm syndrome" with detachment of sperm head from the flagellum due to impaired head-tail coupling. However, molecular function of centrobin in spermiogenesis is still unknown. Sperm decapitation is a distinct phenotype described in several mouse mutants and importantly from infertile human males. Strikingly, in addition to proteins functioning in cytoskeletal...
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