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The effect of steroid hormones on sexually dimorphic bone growth in geckos
Tureček, Adam ; Kubička, Lukáš (advisor) ; Frýdlová, Petra (referee)
The sexual size dimorphism (SSD) is widespread among animals but proximate mechanisms of its ontogeny are still poorly understood even in important groups of vertebrates such as reptiles. Previous experiments in geckos showed that growth of both sexes slows substantially at their older age. Their SSD develops considerably a long time after sexual maturity, it is associated with earlier growth deceleration in the smaller sex and it is controlled by ovarian rather than testicular steroids. The aim of the thesis was to explore the previous knowledge by studying the ontogenesis of the sexually-dimorphic bone growth of the gecko Paroedura picta, the male- larger species with the most explored proximate mechanisms of SSD among geckos. I was most interested in the ontogeny of the growth plates activity and the epiphyseal ossification of the femur in both sexes and their relationship to age, body length, gonadal activity and levels of sex-specific steroids (estradiol and testosterone). The results show that P. picta has determinate growth and that epiphyseal ossification does not contribute to the SSD. The femoral growth plates close at the same age in both sexes; however, their closure occurs at smaller body length in females than in males. In the context of this and the previous studies, estradiol or other...
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Less common metabolites of steroid hormones in human physiology and pathophysiology.
Máčová, Ludmila
Less common metabolites of steroid hormones in human physiology and pathophysiology Not long ago, they have been less common steroid metabolites regarded as mere degradation products of steroid metabolism. Since the last decades, it has been discovered that these substances, which are occurring in the human organism at Nano molar concentrations, are involved in the regulation of physiological processes, such as the immune response, thermoregulation, development of cancer and activity against the major steroids. As the introduction, the presented thesis provides an overview of published data dealing with the less common metabolites of steroids. Experimental part is based on partial studies whose objectives were chosen in such a way to help reveal some of the missing intermediate steps in the mechanism of steroid hormones action. Because these steroids occur in only Nano molar concentrations, the highly sensitive and specific methods such as radio-immuno assay (RIA), gas chromatography combined with mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) had to be used. In the case of metabolites 16α-hydroxy-dehydroepiandrosterone and 7-oxo- dehydroepiandrosterone, we developed and statistically evaluated two novel RIA methods. These rapid and sensitive methods suitable for...
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The analysis of cerebrospinal fluid in patients with hydrocephalus
Chlupáčová, Tereza ; Kolátorová, Lucie (advisor) ; Dušková, Michaela (referee)
Normotensive hydrocephalus (NPH) is a neurodegenerative disease that occurs mainly in patients of high age. The disorder causes accumulation of cerebrospinal fluid (CSF), which leads to enlargement of ventricles and pressure exerted on cerebral structures. Clinical manifestations (gait disorders, development of dementia, incontinence) can be easily confused with symptoms of other neurodegenerative diseases; unlike other such disorders, however, NPH can be treated by surgery, if diagnosed in time. Patients are indicated for the procedure by a lumbar drainage test. There are currently no reliable laboratory biomarkers known that could be the basis of NPH diagnostics. In the past, steroids proved to be linked to neuronal activity in neurodegenerative diseases with the help of specific diagnostic markers. An instrumental method has been developed for the purposes of this thesis and it was used to gauge the level of certain steroids in CSF in a sample group of NPH patients and a control sample group of healthy individuals. A significant difference has been found in levels of aldosterone and cortisone. Aldosterone was higher in NPH sufferers, while cortisone levels were higher in the control group. It is crucial to differentiate patients with NPH from patients with similar clinical manifestations during...
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Endocrine disruptors in reptiles
Semerád, Jaroslav ; Kratochvíl, Lukáš (advisor) ; Cajthaml, Tomáš (referee)
The ability of environmental contaminants to influence reproduction and development in vertebrates via disruption of the endocrine system is widespread. The mechanisms through which xenobiotics act can be complex and vary greatly among species. Reptiles are particularly good models for studying endocrine affecting compounds due to the fact that different species differ in modes of sex determination (genotypic sex determination or temperature-dependent sex determination) and parity (oviparity or viviparity). The sex of individual is often determined by egg incubation temperature, and exogenous application of steroid hormones and their analogs or steroidogenic enzyme inhibitors can reproduce effects of temperature. The lability of sex determination in some reptile species offers opportunity to use gonadal sex as a marker for effects of endocrine disrupting compounds (EDC), even for the effects of extremely low dosages of EDCs or EDC mixtures. The neonatal offsprings exposed to EDCs during embryogenesis provide yet another way to assess endocrine disruption, i.e., measurement of steroid hormone levels in their blood. In addition, many reptile species are highly aquatic, they use habitats near agricultural areas, where usage of pesticides is the most intense, and they are carnivores or scavengers. Therefore,...
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Role of steroid hormones in control of sexually dimorphic traits in eyelid geckos (Eublepharidae)
Tóthová, Lucia ; Kratochvíl, Lukáš (advisor) ; Landová, Eva (referee)
The importance of sex hormones in formation, development and regulation of sexually dimorphic behavior does not need to be stressed. However, their actual organizational and activational effects and interactions in sexual differentiation and determination are not fully understood yet. The aim of our study was to explore the effects of hormonal manipulation in eyelid-geckos (family Eublepharidae) and enlighten the role of steroid hormones in formation of sexual differences. In the first part of our work we tried to reverse sex of Yucatán banded gecko (Coleonyx elegans) by hormonal manipulation in the early embryogenesis. This species has genotypic sex determination with chromosome set X1X2Y. In reverted individuals we aimed to examine the effects of steroid hormones on sexually dimorphic traits and in case of full sexual reversion and fertility of progeny, we would search for the sex-determining gene. In the second part, we studied masculinization effects of testosterone in females of leopard gecko (Eublepharis macularius). In contrast with the Coleonyx elegans mentioned above, this species has temperature dependent sex determination, even though these two species are closely related. Experimental females were implanted with testosterone implants and therefore their testosterone levels were increased in...
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Hormonal control of aggressive behaviour in lizards
Rauner, Petr ; Kratochvíl, Lukáš (advisor) ; Gregorovičová, Martina (referee)
Aggression is a highly functional form of social behaviour, which can be observed in nearly all species of vertebrates including lizards. There are many forms of aggressive behaviour and there is very significant difference in the physiological basis among them. The main and best understood hormone affecting aggression, is testosterone, but there exists evidence that some aggressive behaviour can be influenced by other hormones as well for example by progesterone, estradiol and corticosterone. The effect of these hormones on the organism is traditionally divided into the activation and organizational effects. Organizational effects are permanent and occur usually in the earlier stages of development. Activation effects are temporary and occur during the entire life. Elevated testosterone levels usually stimulate aggressive behaviour in both males and females. Progesterone and estradiol affect aggressive behaviour similarly but less effective. It is uncertain whether their effects are direct, or whether they are only a side-effect of testosterone, which is a precursor of estradiol and which has progesterone as own precursor. Corticosterone affects aggressive behaviour indirectly by influencing levels of testosterone. Hormonal influence on aggression in lizards is not the sole factor, but it depends on...
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Less common metabolites of steroid hormones in human physiology and pathophysiology.
Máčová, Ludmila ; Hampl, Richard (advisor) ; Rauch, Pavel (referee) ; Černý, Ivan (referee)
The thesis focuses on selected, yet unsolved question of the role of less common steroids and SHBG as a junction of three endocrine systems. Answering these questions may help to understand the complex mechanism of action of these hormones on the human organism. This thesis is based on five author and co-written studies mostly published in foreign scientific journals. In the case of studies of metabolites 16α-OH-DHEA and 7-oxo-DHEA (Zamrazilová et al., 2007; Kazihnitková et al., 2007) were focused on the development of appropriate methodological approach because recently used methods showed a low sensitivity and specificity. We developed and statistically evaluated new RIA methods which are rapid, sensitive and inexpensive. Both of them can be used in other research even in routine practice. New methods were also used to determine the metabolites in a statistically significant sample of healthy human population. In another study (Zamrazilová et al., 2010) we examined the relationships of selected steroid metabolites and SHBG in patients with CAH. We assumed that SHBG may act as a non-steroidal laboratory parameter reflecting the effectiveness of substitution therapy in these patients. Our assumption was not confirmed. We observed lower levels of SHBG which at least in women reflect effects of...
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Application of passive sampling for the analysis of hormones in drinking water
Remerová, Martina ; Mravcová, Ludmila (referee) ; Čáslavský, Josef (advisor)
The thesis focuses on the use of passive sampling during an analysis of hormones in drinkable water. In the theoretical part there are described selected passive samplers and the sample of the type of POCIS is described at fuller length. The next chapter engages with steroid hormones and an input of estrogenic hormone into the environment. The thesis contains chapters dealing with possibilities of the determination of hormones in water. It is specialized on the analysis of drinkable and surface water. In the last chapter of the theoretical part there are introduced water works where samples for an experimental assessment were collected from. The experimental part of the thesis presents the specification of the extraction of analytes and an adjustment of used device. In the thesis there are specific calibrations for individual assessment of hormones. The results of the assessment for each collection point are ordered to a well-arranged table. Increased levels of targeted estrogens were not approved in most of sampling points.
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Hormones and their presence in environmental
Sučková, Tereza ; Dvořáková, Petra (referee) ; Vávrová, Milada (advisor)
This thesis deals with the issue of hormones in the environment and analytical methods for the determination of hormonal substances in water and soil ecosystems. The thesis includes an overview of important hormone groups (divided into categories according to their chemical structure) and basic information about properties of chosen hormones, their sources and impacts on the environment. The next focuses upon methods of determination of hormones in soil and water ecosystems. Finally, a standard operational manual for analysis of estrogens in surface water has been created and is provided herein.
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