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Secondary metabolites in fungal pathogenesis
Veselý, Martin ; Čmoková, Adéla (advisor) ; Machová, Lenka (referee)
The ability of fungal pathogens to induce infection and later survive in its host is dependent on virulence factors. Often these factors are based on primary metabolites (hydrophobins, proteases, phospholipases, catalases etc.). Nonetheless many pathogen produced secondary metabolites are also involved in the infection process. Their true role during infection used to be rather undervalued. First part of this bachelor degree thesis aims to describe host-pathogen relation and afterwards introduce reader with some basic, commonly accepted virulence factors of fungi. In the second part of this thesis known roles of secondary metabolites are described in each stages of progressing infection. In the first stage a pathogen needs to create a suitable habitat on host tissues to ensure growth. This is in part done by antimicrobial substances (...). In later stages pathogen prevents phagocytosis of its spores by host (melanins). Successful infection is often accompanied with host tissue damage that is induced by production of cytotoxic substances (xanthomegnin, riboflavin) and immunoregulation of host immune system (gliotoxin, pseurotin). Last but not least there are virulence factors that ensure prolonged survival in host (siderophores). Fungal pathogens of poikiloterm animals are mostly not primary...
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Mechanisms of relationship between melanin-based colouration and behavioural syndromes in birds
Nacházelová, Martina ; Javůrková, Veronika (advisor) ; Tomášek, Oldřich (referee)
Melanins are the most common pigments incorporated into birds' feathers. Since melanin-based coloration is variable in the extent and intensity, its function is considered to be particularly cryptic and mechanical, hardening the feather structure. However, recently it has been found that melanin- based coloration also has a signaling function, due to the observed correlation between this type of coloration and many physiological and behavioral traits. These relationships follow from the pleiotropic effects of genes regulating the melanocortin system and the physiological effects of testosterone and corticosterone, which are involved in melanogenesis. This work describes genetic and physiological mechanisms of the relationship between melanin-based coloration and behavioral traits in birds and, based on available studies, supports the signaling function of this type of coloration. Melanin-based coloration has been shown to be positively correlated with aggressiveness and dominance, sexual activity, coping with stress, a fast strategy of exploratory behavior, parental care, and anti-predator behavior in many bird species. However, despite intense research interest in this topic in last decade, it is worth noting that more experiments focused on species with a distinct sexual dichromatism or...
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Effects of melanin-based coloration and commensalism on performance in behavioural tests: a comparative study
Kahounová, Hana ; Frynta, Daniel (advisor) ; Šumbera, Radim (referee)
An intraspecific coat colour polymorphism exists in the genus Acomys. Some populations are dark and others are light-colored. Dark populations live in lava deserts, savannas and in the commensal habitat of Egypt. The subject of this thesis is to compare selected populations of Acomys in behavioral test of forced exploration. They are dark commensal, light secondary non-commensal, light non- commensal, and one dark non-commensal populations. The aim of this research is to find out whether the dark commensal populations of Acomys cahirinus differ in behavior from other populations and whether dark populations differ in behavior from light populations. According to the results, the observed behavioral parameters do not show significant differences between populations. The dark commensal populations of A. cahirinus did not differ significantly from other populations in exploratory behavior. But the dark populations preferred a dark background. No apparent differences in behavior between differently colored populations were found. However, the variability in tested behavior between populations was found. Key words: exploratory behavior, melanin, commensalism, comparative approach, open field test, Acomys
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Signaling function of plumage coloration in Yellowhammer males
Kauzál, Ondřej ; Petrusková, Tereza (advisor) ; Šálek, Miroslav (referee)
Sexual selection theory tries to explain evolution of apparently useless traits which mainly developed in males of numerous species. One such trait is also rich and vibrant coloration, typical for many of the bird species. These traits are difficult to be falsified, and therefore they honestly signal quality of the individual. Carotenoid coloration reflects the health condition and melanin coloration the social status, even though this traditional division might not be as strict according to the latest studies. Apart from these ways of maintaining honesty, recent studies are focusing more also on the effect of hormones, mainly two steroids: male sexual hormone - testosterone -, and the "stress" hormone - corticosterone. Both hormones could positively influence male's sexual traits such as ornamental coloration. On the other hand, elevated levels of these hormones possess risk to the organism (higher energetic expenditure, chronic stress), therefore also might potentially become costly. Using photographs of birds in standardized conditions as well as spectrophotometry I analyzed the plumage coloration of males of the Yellowhammer (Emberiza citrinella). Concentrations of testosterone and corticosterone deposited in feathers were analyzed using the LC-MS/MS. Also, for males in breeding season 2015,...
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The interaction of lactase persistence and skin depigmentation in connection with the calcium assimilation hypothesis
Grendelová, Gréta ; Černý, Viktor (advisor) ; Brůžek, Jaroslav (referee)
The most recent genetic studies have proven that skin colour of our European ancestors was originally very dark. Skin depigmentation has begun after "out of Africa" time as a result of low levels of the ultraviolet radiation in changed regions at the higher latitudes. Lightly pigmented skin allows sunlight to penetrate human skin more deeply and vitamin D, which is essential for optimal functions of human body, is synthesised by biochemical interaction of ultraviolet radiation and epidermis. A deficit of vitamin D and calcium may be associated with the rickets in children and osteomalacia in adults. Following the correlation of rising depigmentation at the higher latitudes we may notice an increasing number of people with specific metabolic ability known as lactase persistence. Lactase persistence allows the digestion of milk sugar, lactose, in fresh milk in adulthood. It has likely evolved as a substitute in order to compensate for lower amounts of vitamin D in human body. The origin and spread of lactase persistence began around 7,000 years ago after the start of milk production. The oldest evidence of milk production was found in the Middle East. Lately, it has also been supported by the recent genetic analyses. Depigmentation and lactase persistence both began as an adaptation due to changed...
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Mechanisms of relationship between melanin-based colouration and behavioural syndromes in birds
Nacházelová, Martina ; Javůrková, Veronika (advisor) ; Tomášek, Oldřich (referee)
Melanins are the most common pigments incorporated into birds' feathers. Since melanin-based coloration is variable in the extent and intensity, its function is considered to be particularly cryptic and mechanical, hardening the feather structure. However, recently it has been found that melanin- based coloration also has a signaling function, due to the observed correlation between this type of coloration and many physiological and behavioral traits. These relationships follow from the pleiotropic effects of genes regulating the melanocortin system and the physiological effects of testosterone and corticosterone, which are involved in melanogenesis. This work describes genetic and physiological mechanisms of the relationship between melanin-based coloration and behavioral traits in birds and, based on available studies, supports the signaling function of this type of coloration. Melanin-based coloration has been shown to be positively correlated with aggressiveness and dominance, sexual activity, coping with stress, a fast strategy of exploratory behavior, parental care, and anti-predator behavior in many bird species. However, despite intense research interest in this topic in last decade, it is worth noting that more experiments focused on species with a distinct sexual dichromatism or...
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Variability of skin colour: causes and implications
Mašek, Jan ; Černý, Viktor (advisor) ; Hora, Martin (referee)
Melanin acts as a solar radiation filter. Genes are responsible for the amount and the type of the melanin produced, however also an UV radiation is able to induce a melanin synthesis. It appears that the UV radiation has been the determining factor in the human evolution to which the skin colour had to adapt. The original colour of skin was fair and pigmentation has developed after the loss of fur. High levels of UV radiation in equatorial Africa presented a selection pressure for dark pigmentation due to its negative effect on skin. On the other hand, it is important that the skin is bright enough so that a part of the UV radiation could pass through and launch the synthesis of vitamin D. When anatomically modern humans spread out of Africa, a decrease in pigmentation occurred in order to adapt for new levels of the UV radiation in new regions. Nutrition and sexual selection also have an effect on the formation of the skin colour but they have rather secondary importance. The variability of this trait is high between populations but very low within the populations, what testifies to a very intense natural selection. It has also been proven that there is a connection between civilization diseases, such as cancer. Differences in the skin colour have also been and still are important for social...
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Albinismus ve světě zvířat
NĚMCOVÁ, Klára
The subject of this thesis was to prepare an overview of the information on albinism in animals, characterize its different types and origins. Albinism can be divided into full or partial. This depends on whether the affected individual is all white or whether only some body parts are affected. Another type of albinism is leucism. These animals have affected fur and feathers, but skin is pigmented normally. Albinism is a hereditary disease, but it can also arise during the life, for example, due to stress or illness. It is caused by the absence or lack of dark skin pigment - melanin. As melanin protects skin and eyes from sunlight, affected animals suffer from skin diseases and photophobia. In this thesis, the diversity of this disease is documented on examples of various animals - invertebrates and vertebrates.
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Active ingredients in sun cosmetics
Jochimová, Eva ; Vránová, Dana (referee) ; Zemanová, Jana (advisor)
Active substances in sun cosmetics mean quantity and properties of UV-filters that absorb rays in UVA or in UVB areas. In the United States of America there are they considered as pharmaceuticals, however in European Union are they taken behind cosmetics. Their usage is very important, because the sun radiation can be very dangerous. Hazard of negative influences increases largely by downgrade of atmosphere and above all by enlargement of ozone hole. UVB and UVA rays penetrate into the skin where they can be a cause of different disorders. They evocate simply as far as heavily curable photodermatosis, skin ageing and cutaneous carcinoma in worse case.
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Genetika zbarvení činčil
Poslušná, Michala
There are same principles for color coat genesis for all mammals, both on a molecular level and when the final phenotype is created. Even in the early embryonic stage the cells for pigment deposition are distributed to the periphery parts of the body, skin cells and hairfollicles. The most important substance for color coat genesis is melanin pigment, whose synthesis is affected by melanocortin and two basic pigments eumelanin a pheomelanin are made by enzymatic cycles. The final phenotype is influenced by 5 or 6 basic genes, their mutations and interaction between them. Model system for showing the creation of color coat is mice. Chinchilla's, whom the work is dedicated to, genes and alelles haven't been described in exact way yet, but it is supposed, that basic principles are the same as in mice and the knowledge of color coat genetics in rodents are based on this claim. Breeders use allele indication made by themselves and genotype is determined by the animal's phenotype. The phenotype of offspring is determined by genotype of both parents.
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