National Repository of Grey Literature 6 records found  Search took 0.00 seconds. 
Effect of selected pollutants on mammalian organisms in vivo and cells in vitro and preparation of specific monoclonal antibodies for their detection
Dorosh, Andriy ; Pěknicová, Jana (advisor) ; Linhart, Otomar (referee) ; Motlík, Jan (referee)
Environmental pollution and its effect on the living organisms has attracted lots of attention recently. There is a growing body of evidence that we are exposed to environmental pollutants at low concentrations in everyday life. The cells and organisms have tools to identify, neutralize and excrete the majority of the toxic compounds. The most dangerous are those that can escape this process or act at low trace concentrations. Endocrine disruptors (EDs) belong to the latter group. Endocrine disruptors can be of natural and anthropogenic origin. EDs target corresponding hormonal receptors and can act at low concentrations. A wide family of nuclear receptors recognize steroid hormones. The majority of EDs can pass through the cytoplasmic membrane, use the hydrophobic nature of the receptor-ligand binding, trigger hormone response and change the expression of the sensitive genes. By interfering with estrogen and androgen signaling, EDs can have effect on the whole organism, but the reproductive system is influenced most. In the present work, our aim was to develop the methods for ED detection and monitoring, analyze the estrogenic potency of EDs, and evaluate the effects of natural estrogens and EDs on male reproductive functions, including sperm and testicular physiology and endocrine functions. First, we...
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...
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 influence of estrogens on mouse sperm capacitation and acrosome reaction in vitro
Tejnická, Magda ; Hortová, Kateřina (advisor) ; Linhart, Otomar (referee)
There are an increasing amount of compounds in the environment that can have a negative effect on reproductive parameters in both male and female organism. There has been a worldwide decline of sperm quality during past decades and this fact lead to an increase of unnatural ways of conception through assisted reproduction techniques in the specialised centres. Natural estrogens are one of these compounds and they get into waste water after being excluded from the body by the urine. They get back into the human body from drinking water or from the food, and they can interfere with function of endogenous hormones in very low concentrations. For these reasons it is up to date to deal with the influence of these compounds on mammalian sperm. For many years, estrogens have been considered typically female sex hormones. It is now certain that they are also very important in the regulation of male reproduction. Endogenous estrogens in mammalian males are an important part of the endocrine system. Estrogens play an important role in the development of germ cells, spermatogenesis and processes leading to successful egg fertilization such as a capacitation or acrosomal reaction. Tyrosine phosphorylation is one of the essential steps for the properly ongoing process of capacitation in sperm followed by a...
Functions of different song types and song structures in songbirds
Pišvejcová, Iveta ; Petrusková, Tereza (advisor) ; Linhart, Otomar (referee)
In this review I summarize information about different types of song and its structures in which has been well documented their context of use. I have tried to find out, if there are some generally valid rules. The work is aimed at Passerines (Passeriformes) males living in the temperate zone. They sing the most intensively after their arrival on breeding grounds in early spring. Depending on a species and moreover an individual, the song might differ in structure, time and frequency parameters. Some species use complex songs, and change the way of its production according to attending audience. In such cases, the length and versatility of the song (the number and variability of syllables) may reflect the quality of a male. On the other hand some species with a simple song use different criteria to assess the singer quality. The individuals then differ in the way of song production or just in use of particular structures. For example, wide frequency range and length are considered to be energy-demanding for production, and so it could be a suitable indicator for a male quality. Short syllables produced at a faster rate can be not only production-demanding but can also indicate aggression. In general, we can estimate the function of a produced song according to "mating status" (before and after pairing) and...
Genetická struktura populací lína Tinca tinca (Linnaeus, 1758)
Lajbner, Zdeněk ; Linhart, Otomar ; Kotlík, Petr
The tench is an important fish for aquaculture, which is undergoing intensive domestication, but only few studies have examined genetic structure of its populations. We present first results of a phylogeographic study based on DNA sequence data for four nuclear genes and one mitochondrial DNA gene from throughout the tench geographical distribution, including some of the known transfers outside its native Eurasian range. The multiple gene dataset revealed a strong phylogeographic partitioning between the western and eastern parts of the species range with a wide zone of overlap in Europe. Tench in European aquaculture largely represent mixtures of the two evolutionary lineages. We will discuss the likely historical processes underlying these findings. We suggest that human-mediated dispersal may have played an important role in shaping the present phylogeographic pattern.

See also: similar author names
7 LINHART, Ondřej
7 Linhart, Ondřej
1 Linhart, Otto
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