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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 role of integrins in gametes prior to fertilization and during their interaction
Foldynová, Veronika ; Komrsková, Kateřina (advisor) ; Tlapáková, Tereza (referee)
Integrins are heterodimeric transmembrane glycoproteins that represent a large group of cell adhesion receptors involved in cell-cell, cell-extracellular matrix and cell-pathogen interacti- ons. Up to now, 24 different integrin heterodimers have been detected in mammals. They are involved in a wide range of processes such as immune response, lymphocyte homing, platelet aggregation, also in wound healing, cell differentiation, migration, proliferation and even in cell survival. Integrins have also been detected on germ cells and are now known to play an important role in reproductive processes such as fertilization, embryo implan- tation, and embryonic development. The main aim of this thesis is to introduce integrins from the perspective of reproduction, integrin physiology, occurrence and localization of individual subunits in male and female germ cells. A significant part of the work is devoted to a discussion of the role of integrins in gametes, both during maturation processes (egg maturation in the ovary, capacitation and the acrosomal reaction of sperm), in sperm mi- gration, oviductal reservoir formation and their direct and indirect involvement in adhesion and fusion of the gametes during fertilization. Keywords: integrins, sperm, egg, fusion, fertilization
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Methods of sperm selection for human and veterinary assisted reproduction
Pavlová, Hana ; Komrsková, Kateřina (advisor) ; Koubek, Pavel (referee)
Sperm selection is an important process influencing the progress of fertilization and the quality of resulting embryos. Competent sperm cells can be isolated from an ejaculate sample according to different criteria. Standard methods allow for sperm selection based on conventional parameters, particularly motility and density. Using advanced methods, sperm cells are selected according to molecular aspects including for instance membrane charge, presence of specific receptors, molecules indicating ongoing apoptosis, and others. The latter procedures are widely used particularly in human practice. Their use is uneconomical in veterinary practice and standard methods including the centrifugation step in the procedure are primarily used to select the sperm of livestock. Sperm cells of livestock are also often selected according to whether it carries the X or Y chromosome. Thus, the sex of the offspring can be effectively determined in order to increase the efficiency of the production of animal products. This thesis presents the most frequently used methods of sperm selection for the purpose of oocyte fertilization in human and veterinary sectors of assisted reproduction and discusses their impact on the parameters and fertilization potential of isolated cells.
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The role of LINC complex in male germinal cells
Kmoníčková, Věra ; Komrsková, Kateřina (advisor) ; Knop, Filip (referee)
LINC (linker of the nucleoskeleton and cytoskeleton) complex is substantial for the overall function of any nuclear cell. It is a bridge between the cytoplasmic and nuclear structures which mediates transmission of mechanical forces generated on the cytoplasmic side. The main objective of this thesis is the function of distinct variants of the LINC complexes in mammalian male germinal cells throughout their development. The nuclear facing side of the LINC complex is a key player in homolog pairing and rapid chromosome movements during meiosis. The cytoplasmic facing side is necessary for the sperm head formation, proper acrosome and nucleus attachment. Evenly, another complex is essential for the head-to-tail coupling as without this one the sperm cells are found decapitated. If the subunits of the LINC complex are defective, males are afflicted with different kinds of infertilities, which nowadays is one of the important issues of our society. Many things about the role and structure of the LINC complex has been discovered due to modern technologies. These up to date findings are summarized and discussed on the following pages.
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Chemical communication of gametes
Otčenášková, Tereza ; Komrsková, Kateřina (advisor) ; Petr, Jaroslav (referee)
Fertilization is a multiple step process leading to fusion of female and male gametes resulting in a formation of a zygote. Besides direct gamete interaction via binding receptors localized on both oocyte and sperm surface, fertilization also involves communication based on chemical molecules triggering various signalling pathways. This work is aimed to characterize chemical communication of gametes of a model organism Mus musculus. For this purpose, modern proteomic and visualisation methods like nano-liquid chromatography tandem mass spectrometry (nLC-MS/MS), selected reaction monitoring (SRM) and immunofluorescent microscopy were used. Lipocalins were identified as candidate proteins involved in communication including those from major urinary proteins (MUPs), LCN lipocalins and fatty acid binding proteins (FABPs). For the first time, we report their presence in the sperm acrosome. Based on lipocalins capacity to bind and transport other molecules, we propose that these proteins have a protective and/or signalling role for gametes. Furthermore, chemical communication between sperm and oocyte is based on chemotaxis which enables their interaction before their fusion. In this work, we detected that spermatozoa show chemotactic responses in the presence of L-glutamate. This amino acid naturally...
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Cytoskeleton-membrane protein interaction network in sperm
Adamová, Zuzana ; Komrsková, Kateřina (advisor) ; Tolde, Ondřej (referee)
In order to fertilize the egg, sperm cell undergoes several subsequent maturation processes. The final one called acrosome reaction is an exocytosis of acrosome vesicle, which is filled with lytic enzymes. Acrosome reaction is crucial for penetration of the sperm cell through the egg surroundings, especially zona pellucida, as well as for reorganization of a membrane protein composition on its surface. This rearrangement leads to the exposure of proteins essential for fertilization, mainly for gamete recognition, binding and fusion in specific compartments of the sperm head. One of such protein is CD46, which is located in the acrosomal membrane of an intact sperm and after acosomal exocytosis it relocates to the equatorial segment of a sperm head, which is known to be the initial site of interaction of sperm with the egg plasma membrane. The relocation of CD46 is disrupted by inhibition of actin, which reorganization within sperm head is known to play a role in onset of acrosome reaction, however, the precise mechanism of CD46 interaction with actin in sperm is unknown. In this thesis, ezrin - a crosslinker of membrane proteins and actin - has been studied in context of CD46 and its relocation across the sperm head. Analysis of the immunofluorescent detection of ezrin revealed its mutual...
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Male infertility in context of testicular cancer
Cimlerová, Markéta ; Komrsková, Kateřina (advisor) ; Truksa, Jaroslav (referee)
This bachelor thesis focuses on male infertility in a connection to testicular cancer. Testicular cancer is the most common malignancy among young men in a reproductive age and the worldwide incidence of testicular cancer is on the rise. A lot of attention is also given to an increasing rate of infertility in a context of testicular cancer. For these reasons, the aim of this thesis is to clarify several non-physiological changes, such as hormone levels, spermatogenesis and sperm parameters, which take place in a male body and influence the chance to become a biological father. These pathological changes can be due to the disease itself but also due to the treatment. A cryopreservation of semen is also going to be discussed as the way to preserve male fertility and as an option for couples with the infertility problems due to male factor which rely on help of the assisted reprodiction. Kye words: testicular cancer, cancer treatment, male infertility, sperm parameters, mitochondria, assisted reproduction
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Biological imaging by super-resolution microscopy
Adamová, Zuzana ; Komrsková, Kateřina (advisor) ; Benda, Aleš (referee)
zuzana_adamova_abstract_eng.txt[11.05.2017 20:26:29] Fluorescence microscopy is one of the most widely used imaging techniques in biological research. Despite its numerous advantages, it can be used only for studies of structures larger than 200 nanometres, due to diffraction limit caused by a wave nature of light. The value of 200 nanometres is the best reachable value of optical resolution, in other words, the smallest distance of two objects, which can be separately recognized by conventional optical systems. Up to the end of the 20th century it was therefore impossible to observe finer details of cells. However, recently several breakthrough imaging techniques, named super-resolution microscopy techniques, managed to bypass the diffraction limit and enabled biologists to study much more delicate structures, such as small organelles, virions, protein complexes or even particular proteins, while still using a visual light. This thesis introduces some selected super-resolution methods, explains briefly their principles and presents some of their applications in biology.
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Monitoring of selected steroid hormones by HPLC-MS/MS and studying their impact on mouse sperm in vitro.
Bosáková, Tereza ; Komrsková, Kateřina (advisor) ; Pacáková, Věra (referee)
The present project aims were development of a new sensitive separation method using high performance liquid chromatography with tandem mass spectrometric detection, which enables quantification of selected steroid hormones, namely 17α-ethynylestradiol (EE2) and progesterone (PRG) in M2 fertilizing medium. M2 medium is used during sperm capacitation in vitro, which is the physiological process of complex molecular and biochemical changes, essential for obtaining fertilizing ability of male gametes. Optimized separation and detection conditions (column Kinetex EVO C18 with mobile phase consisted of 50/50 (v/v) acetonitrile/water with 0.1% formic acid in both components) were applied on monitoring of concentration changes of each hormone during time dependent sperm capacitation. The concentration tested for EE2 were 200, 20 and 2 µg/l and for PRG 200 µg/l only. It was found that concentration of free, unbounded EE2 firstly decreases, reaches the minimum in about 60 min of capacitation and then increases again. This trend was observed for all three tested concentrations. Concentration (200 µg/l) of free unbounded PRG decreased during whole capacitation. The following kinetic analysis will be based on the concentration dependences of the free unbound hormones on the capacitation time. The results of...
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Chemical communication of gametes
Otčenášková, Tereza ; Komrsková, Kateřina (advisor) ; Petelák, Aleš (referee)
Many diverse chemoattractants play a part in sperm guidance towards the oocyte without any difference whether organisms with external or internal fertilization. Upon release, spermatozoa are exposed to various cues providing essential information about their surrounding environment. These molecules are structurally very distinct and they induce via specific receptors, expressed over the sperm cell surface, different signalling pathways influencing the sperm motility and regulating the correct sperm function. The overall understanding of these mechanisms brings interesting and often unexpected points of view on evolutionary relationships between invertebrate and vertebrate species. Some principles believed to be shown exclusively only by mammals are nowadays revealed also by marine invertebrates and vice versa. The current knowledge of human gametes interactions is used in fields of medicine that are connected to the reproduction. Thus, with a help of current knowledge, researches aim to shed more light into causes of infertility, as well as to develop novel contraceptives or enhance the rate of successful in vitro fertilizations.
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