National Repository of Grey Literature 70 records found  beginprevious34 - 43nextend  jump to record: Search took 0.00 seconds. 
Interactive effects of carotenoid supplementation and oxidative stress on sperm morphology, sperm quality and spermatogenesis in the Zebra finches
Bílková, Karolína ; Albrecht, Tomáš (advisor) ; Jonáková, Věra (referee)
The phenotype-linked fertility hypothesis predicts that both, male carotenoid-based sexual ornamentation and their spermatozoa are phenotypically plastic and may be co-affected by the environment. One of the factors affecting their phenotype may be oxidative stress and the ability of organism to eliminate its effect. Oxidative stress may reduce sperm quality because sperm lack the ability to repair DNA, but it can also affect spermatogenesis itself. However, some substances may function as antioxidants, and thus eliminate effect of reactive oxygen species (oxidative stress) in the body. In this study, adult zebra finch males (Taeniopygia guttata) originating from the domesticated and recently wild-derived populations were exposed to the diquat (D), which enhances the oxidative stress, and carotenoid lutein (L), which could have an antioxidant function. Experimental design had factorial character 2x2 with a control (group L, D, LD, control). Neither oxidative stress, carotenoids, nor their interactions affected sperm morphology or velocity and it also did not increase abnormal sperm proportion in the ejaculate. However, the differences were observed at the molecular level, where by inducing the oxidative stress, the sperm had reduced signal intensity of acetylated α-tubulin in the sperm tails....
Distribution of predators, predation risk and antipredation strategies in waterfowl
Kreisinger, Jakub ; Albrecht, Tomáš (advisor) ; Bureš, Stanislav (referee) ; Tkadlec, Emil (referee)
Jakub Kreisinger - summary of the Ph.D. thesis: Predation is an important selective force affecting many evolutionary and ecological process. Anthropogenic landscape changes often alter these processes due to qualitative and quantitative changes in the predator comunity. This thesis contains four papers that are focused on various aspects of the nest predation, antipredation strategies and distribution of predators in the landscape modified by human activities. The first contribution "Nest protection in mallards (Anas plathyrhynchos): Untangling the role of crypsis and parental behaviour" (Kreisinger & Albrecht 2008) focus on the effect of antipredation strategies on the reproductive success in a ground nesting bird, mallard. Our data are consistent with the hypothesis that multiple antipredation strategies including nest site selection parental antipredation behavior and crypsis due to clutch concealment by the nest material during incubation recesses reduce sumultaniousely the risk of the clutch predation in birds. Contrary to some previous studies, the relative effects of crypsis and parental anti-predation behaviour on nest survival did not differ with respect to antipredation effect of the nest concealment by surrounding vegetation. The hypothesis that linear strips of shrubby vegetation and high grass...
Secondary sexual ornaments and ectoparasites in the barn swallow (Hirundo rustica)
Wichová, Eliška ; Albrecht, Tomáš (advisor) ; Sedláček, Ondřej (referee)
Parasites could represent an important evolutionary driver and play an important role in a sexual selection. In the mate selection process, females use secondary sexual ornaments, which may reflect the parasite load and health condition of males. Females would benefit from choosing males with the most extravagant sexual characters, which indicate low levels of parasite infestation. A popular model species for sexual selection study is the barn swallow (Hirundo rustica). However there are no recent studies investigating the relationship between the level of the ectoparasitic infestation and the ornamentation of the barn swallow. Results of this thesis, based on analysis of ectoparasite load in 204 individuals show, that the level of infestation by feather mites is positively correlated with outermost tail feathers and the intensity of feather holes is negatively correlated with a breast coloration. The relationship between the abundance of ectoparasites and white tail spots was not found. The effect of ectoparasites on the survival of individuals or the nest initiation date was not observed. A possitive relationship between the individual seasonal change in feather mites infestation and brood size was detected. This implies a potential trade-off between the investments into parental care and defence...
Effect of altitude on avian life histories and physiology
Brindzák, Marek ; Albrecht, Tomáš (advisor) ; Ferenc, Michal (referee)
Vliv altitudy na životní strategie a fyziologické nastavení ptáků Řešitel práce: Marek Brindzák Vedoucí práce: doc. Mgr. Tomáš Albrecht, Ph.D. Abstract The pace-of-life syndrome theory proposed that species with similar life-histories share physiological traits that are more similar than species with different life-histories. Despite the fact that life-histories and physiology are well studied in birds it is still unknown how altitude changes these traits. However, shifts in life-histories across latitudinal gradients, with slow pace characterized by high investment to the future reproduction in tropics and fast pace of life characterized by high to the actual reproduction in temperate, is well know. From this knowledge we can assume how birds solve the trade-of between survival and reproduction based on the environmental conditions. This thesis summarizes effect of altitude on selected life-histories and physiology traits, the findings are compared with latitudinal changes. The first part of thesis is focused on describing latitudinal and altitudinal effect on selected avian life-histories traits. The second part deals with the altitudinal effect on the selected physiological traits in birds. Birds breeding at high altitude exhibit novel pace of life with life-histories similar to a slow pace but with...
Telomeres as indicators of chronological and functional age and ageing in birds
Kyliánková, Hana ; Albrecht, Tomáš (advisor) ; Aghová, Tatiana (referee)
The explanation of ageing processes belongs to the most challenging topics in evolutionary biology. This bachelor thesis provides a basic summary of evolutionary hypotheses of ageing, along with an overview of proximate ageing mechanisms. Main focus is on telomeres and the dynamics of their shortening. Telomeres are non-coding, repetitive sequences of DNA protecting the ends of eukaryotic chromosomes against degradation. They usually shorten with each cell division in most somatic cells until they reach the critical limit (the so called Hayflick limit), when the cell undergoes the replicative senescence and does not divide anymore. Various factors, such as physiological/oxidative stress, stage of reproduction/reproductive investments, and diseases/parasites, can influence telomere length dynamics. Recent studies indicate that telomere length is a useful biomarker for estimating functional, or biological age, but at the same time length of telomeres cannot be used to estimate chronological age. Molecular methods which can be used to measure telomere length, and their potential limitations, are also discussed in this thesis. Finally, I provide an overview of studies focusing on telomere dynamics in bird-oriented research. Key words: Telomeres, ageing, qPCR, birds, oxidative stress
Valuation of FOXCONN CZ s.r.o.
Albrecht, Tomáš ; Smrčka, Luboš (advisor) ; Schönfeld, Jaroslav (referee)
The aim of the Master´s Thesis Valuation of FOXCONN CZ s.r.o. is to determine the objectified value of the company FOXCONN CZ s.r.o. as at 31. 12. 2015 from the perspective of an external analyst. The Master´s Thesis is divided into two main parts. The theoretical-methodological part describes the procedure of calculation single methods leading to the final valuation of the company. The emphasis is mainly on description of valuation, strategic analysis, financial analysis, planning of value generators, financial plan and the individual valuation approaches. The practical part is based on the application of particular procedures and calculations, described in the theoretical part. Results of every single chapter are properly commented using relevant information and other facts. The conclusion contents the summary of gained results leading to the determination of final value of the company. Method of free cash flows to equity (FCFE) was used for valuation.

National Repository of Grey Literature : 70 records found   beginprevious34 - 43nextend  jump to record:
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