National Repository of Grey Literature 52 records found  previous11 - 20nextend  jump to record: Search took 0.01 seconds. 
Effect of estrogens and endocrine distruptors on mammalian sperm in vitro and male reproductive parameters in vivo
Děd, Lukáš ; Pěknicová, Jana (advisor) ; Jonáková, Věra (referee) ; Linhart, Otomar (referee)
The endocrine system is one of the most important regulatory systems in human and animal bodies and almost all physiological processes are regulated by it. Human and animal reproduction are largely regulated by different hormones and their proper and well regulated functions are essential for successful production of the gametes, fertilization and related processes, development of the embryo and fetus, initiation of puberty and production of the offspring. Estrogens have generally been considered as primarily female hormones. However, there is increasing evidence of their important impact on male reproductive functions. This was well documented by production of estrogen receptor knock-out male mice, which are infertile. Estrogens and estrogen receptors are also very frequent targets of endocrine disruption. Endocrine disruptors are natural or artificial compounds that, at certain doses, can interfere with the endocrine functions in human and wildlife. This interference can include specific binding to the hormonal receptor, influencing the production, elimination and transport of the natural hormones and also not well documented mechanisms including epigenetic regulations. In the presented work, our aim was to evaluate the effects of natural estrogens and endocrine disruptors on male reproductive...
The study of fluids and secretions from reproductive tracts of pig (Sus scrofa f. domestica) and cattle (Bos primigenius f. taurus)
Dráb, Tomáš ; Liberda, Jiří (advisor) ; Jonáková, Věra (referee) ; Ulčová-Gallová, Zdeňka (referee)
Interactions between proteins and saccharide moieties play an indispensable role in mammalian reproduction as they stand behind of such processes as maturation and mutual recognition of gametes and sperm oviductal reservoir formation. In my dissertation thesis I focused on activities of glycosidases from bovine and porcine follicular fluids and their changes connected with follicle development. Activities of five glycosidases were detected in tertiary and preovulatory follicles in both species. The most active enzymes were α-L-fucosidase in cow and α-D-mannosidase in sow and both enzymes also demonstrated the most pronounced increase in their activities during follicle maturation. Interestingly, both α-L-fucose in cow and α-D-mannose in sow were described as saccharides responsible for the formation of the sperm oviductal reservoir and we offered a hypothetical mechanism of synchronisation between sperm release from their reservoir with the time of ovulation based on a surge of activities of corresponding follicular glycosidases through the oviduct. Subsequently, it was demonstrated that β-D-galactosidase and α-D-mannosidase affect sperm-zona pellucida binding in pig, as they both decrease interaction between sperm receptors for zona pellucida and zona pellucida. This may explain the observation...
The Molecular mechanisms of sperm-egg fusion in mouse
Klinovská, Karolína ; Hortová, Kateřina (advisor) ; Jonáková, Věra (referee)
The mechanism of gamete fusion remains largely unknown on molecular level despite its indisputable significance. A few molecules requisite for membrane interaction are known, among them IZUMO1 on sperm and tetraspanin CD9 on egg. A concept of a large multitprotein complex on both membranes forming a fusion machinery is recently emerging. CD9 is expected to play a role in organizing egg membrane order and to interact laterally with other factors. On the other hand, IZUMO1 contains one immunoglobulin (Ig) domain, which is known for its interaction with various molecules and thus is expected to have a binding partner on the egg membrane. Ig domains are known for their involvement in interactions with Fc receptors and Fc receptor-like molecules, which makes these a potential partner for sperm in gamete binding and fusion. Recent experiments identified Fc receptor-like 3 as a candidate binding partner for sperm by one-bead one-compound assay. The aim of presented study was to assess the localization of FCRL3 in mouse eggs, together with its potential co-localization with IZUMO1 on complexes of zona-free eggs with bound sperm. In this study, FCRL3 molecule has been found across the cytoplasm, possibly in the intracytoplasmic membrane compartments of the cell, as well as on the egg membrane. Its presence...
Sperm morphology and molecular mechanism associated with sperm fertilizing ability in mice.
Šebková, Nataša ; Hortová, 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...
The role of LIF gene mutations and the relative distribution of NK cells, NKT and T lymphocytes in follicular fluid and blood of women with different history of infertility
Křížan, Jiří ; Šíma, Petr (advisor) ; Jonáková, Věra (referee) ; Kročová, Zuzana (referee)
Charles University in Prague Faculty of Natural Sciences Summary of Ph.D. thesis The role of LIF gene mutations and the relative distribution of NK cells, NKT and T lymphocytes in follicular fluid and blood of women with different history of infertility Jiří Křížan Prague 2010 1 | P a g e Doctoral degree programs in biomedicine Charles University in Prague and the Academy of Sciences of the Czech Republic Programme: Biomedicine Chairman of the Subject Board: Doc. RNDr. Vladimír Holáň, Dr.Sc. Place of study: Institute of Microbiology, v.v.i., Academy of the Czech Sciences Vídeňská 1083, 142 20 Prague 4 phone: +420 296 442 318 Autor: Mgr. Jiří Křížan Supervisor: RNDr. Petr Šíma, CSc. The dissertation can be found at Dean's Office Faculty of Charles University in Prague 2 | P a g e CONTENTS Contents 2 Summary 3 1. Introduction 5 2. Hypotheses and aims 6 3. Material and methods 7 Material: 7 Methods: 8 4. Results 10 5. Discussion 12 6. Conclusion 15 7. References 16 Bibliography of Autor: 18 1. papers in extenso (thesis background) 18 2. papers in extenso (without regard to thesis) 19 3 | P a g e SUMMARY The aim of the dissertation thesis "The role of LIF gene mutations and the relative distribution of NK cells, NKT, and T lymphocytes in follicular fluid and blood of women with different history of infertility"...
Regulation of Cathepsin D Activity and Activation
Máša, Martin ; Mareš, Michael (advisor) ; Jonáková, Věra (referee) ; Holada, Karel (referee)
PhD Thesis ABSTRACT REGULATION OF CATHEPSIN D ACTIVITY AND ACTIVATION Martin Máša supervisor: Michael Mareš Department of Biochemistry Faculty of Science Charles University Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic PRAGUE 2009 Introduction Cathepsin D (CD) is an aspartic peptidase located in the lysosomes of all mammalian cells, its main role is catabolic degradation of proteins. More over CD is known to participate in a range of physiological processes such as apoptosis and tissue homeostasis, as well as in the regulation of angiogenesis and the production of peptidic antigens. The role of CD in pathophysiology is associated with several diseases such as Alzheimer's disease and cancer. Alzheimer's disease is a neurodegenerative disorder, which is generally considered to be the most common form of dementia. Progression of this disease is accompanied with the deposition of amyloid plaques (AP) in the brain, which leads to neurodegeneration. The AP is a fragment released from amyloid precursor protein (APP) cleaved by secretases1 . High levels of CD were found in cerebrospinal fluid of the Alzheimer's patients2 . It was demonstrated that CD is able to cleave APP and produce the pathogenic AP. A genetic polymorphism in the CD gene was reported, which changes...
Digestive aspartic protease of Colorado beetle
Srp, Jaroslav ; Jonáková, Věra (referee) ; Konvalinka, Jan (advisor)
Colorado potato beetle (Leptinotarsa decemlineata) is an economically important herbivorous pest. Cathepsin D-like aspartic peptidase (LdCD) plays an important role during protein degradation in the midgut of Colorado potato beetle. This work describes the preparation of two expression systems, namely in Escherichia coli and Pichia pastoris, for the production of recombinant LdCD. The protocol for refolding of denatured LdCD was designed and optimized. Activation of the inactive LdCD zymogen and cleavage of the propetide (activation peptide) were investigated. This process proceeds autocatalytically at acidic pH or with the assistance of the cysteine peptidase legumain. The proteolytic activity of LdCD was characterized using fluorogenic peptidic substrate and protein substrates, and kinetic parameters and pH optimum were determined. The inhibition specificity of LdCD was analyzed using a panel of peptidase inhibitors. LdCD was significantly inhibited by PDI (potato cathepsin D inhibitor), a protein inhibitor produced in potato leaves. This suggests that PDI is a natural defense protein, which is directed against LdCD in the midgut of Colorado potato beetle in order to block the digestion. The potential application of PDI in the construction of transgenic crops resistant against insects is discussed.
The Separation of Gastric Aspartic Proteases Using Affinity Chromatography
Frýdlová, Jana ; Kučerová, Zdenka (advisor) ; Barthová, Jana (referee) ; Jonáková, Věra (referee)
Human gastric juice contains mainly aspartic proteases - pepsin A and pepsin C. Both pepsins are produced by gastric mucosa as inactive pepsinogens (pepsinogen A and pepsinogen C) that differ in their physico-chemical and immunological properties. Both pepsinogens consist of molecular variants, isozymogens. Pepsinogens are activated to the corresponding pepsins in the acidic environment of the gastric lumen. (...) A subject of this Ph.D. thesis is a part of a long-term investigation that focuses on the elaboration of methods for the separation of gastric aspartic proteases that would be suitable for monitoring of their changes in mentioned diseases. This thesis was mainly focused on preparation of affinity sorbents suitable for separation of pepsins and pepsinogens. The choice of ligands was based on the substrate N-acetyl-L-phenylalanyl-3,5-diiodo-L-tyrosine that is used to differentiate pepsin A and pepsin C. The following three affinity sorbents were prepared: iodinated L-tyrosine-Sepharose, 3,5-diiodo-L-tyrosine- Sepharose, and N-acetyl-L-phenylalanine-Sepharose. The basic characteristics of the prepared affinity sorbents were determined using the model enzyme (porcine pepsin A). The comparison of the chromatographic behavior of porcine pepsin A and its complex with pepstatine A showed that the enzyme...
Sperm acrosomal reactien in selected species of mammals
Frolíková, Michaela ; Stopka, Pavel (advisor) ; Jonáková, Věra (referee) ; Petr, Jaroslav (referee)
Mammalian sperm must undergo the process of capacitation - series of physiological and biochemical modifications prior fertilization. In last stage of capacitation sperm undergoes acrosome reaction (AR). During AR the cell membrane of the sperm fuses with the outer acrosomal membrane and the contents of acrosomal vesicle are released into extracellular space. Sperm which did not undergo AR or sperm missing acrosome at all are unable to fertilize. AR results into dramatical changes in the sperm head. Most of the proteins present in plasmatic and outer acrosomal membrane are reorganized or lost. There are also significant changes in cytoskeletal and intraacrosomal proteins are released to extracellular space uncovering new surface domains. Some sperms undergo AR even without presence of inductor of AR during capacitation in vitro. This event is called spontaneous (accelerated) AR. The latest research indicates that spontaneous AR is natural part of the process of fertilization. Field mice (Apodemus) show high level of promiscuity leading to significant risk of sperm competition. Unique reproduction strategy where the sperms form so-called sperm trains was evolved in field mice. Spontaneous AR is probably enabling the dissociation of sperms from the sperm train. The spontaneous AR rate is dependent on...

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