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Helminth-host interactions on hormonal level
Lukesová, Hedvika ; Mikeš, Libor (advisor) ; Horák, Petr (referee)
Interactions between helminths and their hosts at the hormonal level result from their biochemical coevolution. Host hormones play an important role in the life of many helminths, and helminths are able to exploit them in some cases. For example, by expressing their own analogous hormone receptors that bind host hormones. Alternatively, by influencing the levels of host hormones, as certain hormonal environments may be (dis)advantageous for the helminths. This is the case, for example, of male mice infected with Taenia crassiceps, which undergo feminization as a result of infection. Some helminths can produce their own specific factors that influence host physiology, behaviour or appearance and may be analogs (orthologs) of host hormones. An example is the plerocercoid growth factor produced by Diphyllobothrium mansonoides, which behaves very much like a growth hormone in the host, although it differs in its primary structure. Some hormonal interactions can affect both helminth reproduction and the reproduction of their hosts. Examples of host-specific hormones that have been shown to be produced by helminths include, e.g., the ecdysteroid hormones - ecdysone and ecdysterone. A full understanding of the hormonal interactions between helminths and their hosts may lead us to find new treatments for...
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Mesocestoides spp. - the spectrum of species, hosts, and life cycle modes
Zavadil, Ondřej ; Horák, Petr (advisor) ; Skála, Vladimír (referee)
Tapeworms of the genus Mesocestoides, which belong to the order Cyclophyllidea, are parasites of carnivorous vertebrates. Their larvalstages of tetrathyridiaare found in a wide range of tetrapod intermediate hosts. Within the genus, there is an anomalous species Mesocestoides corti, whose tetrathyridia reproduce in hosts by asexual longitudinal division. There is no mention of the possibility of such reproduction in other species. Thus, the laboratory strain of M. corti is widely used as a model organism that is well maintained under in vivo and in vitro conditions due to its asexual reproduction. Four other species are known to occur in the genus and are described by both morphological and molecular data. The remaining known species are named only on the basis of morphology. Adults are characterised by their rare morphology. This includes the ventromedian position of the genital atrium, the paired vitelline glands, and in gravid proglotids, developed paruterine organ, which contains eggs with oncospheres. The life cycle has not been yet explained, but it is assumed that the putative cycle involves three hosts. An alternative hypothesis considers the possibility of a two-host life cycle.
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Blackflies of the Czech Republic and their feeding preferences
Blechová, Karolína ; Brzoňová, Jana (advisor) ; Dvořák, Vít (referee)
Blackflies are globally distributed small flies belonging to the order Diptera, known as common nuisance for humans and vectors of certain parasites. The most commonly transmitted parasites include the genera Onchocerca, Leucocytozoon and Trypanosoma. For humans the most significant species is Onchocerca volvulus, which causes onchocerciasis (or "river blindness") in tropical areas. This thesis is about faunistics of blackflies in the Czech Republic, where was described 45 species of these flies to this date. First mentions of the family Simuliidae are from 19th century. More specific studies about these arthropods have been published since the 1950s and the main concern of these studies was to study blackflies at specific locations. More recent studies put focus primarly on blackflies as vectors. Host preferences are an important aspect in the characterization of blackflies and all vectors in general. Host preferences of blackflies are highly variable among species, ranging from ornitophilic blackflies tied strictly to a single host species (S. euryadminiculum with specifity on common loon) to opportunist species feeding on both mammals and birds (S. vernum). Host preferences have been adressed in only small number of studies. Classic method used for determination of host preference is...
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Strukturně funkční charakteristika průduchů jmelí bílého (Viscum album L.) a jeho hostitele lípy (Tilia sp.)
Bělíček, Dominik
This thesis deals with a comparison of the morphology of the stomata of the hemiparasite European mistletoe (Viscum album L.) and its host lime tree (Tilia sp.) in the context of physiological parameters such as water potential, stomatal conductance, and photosynthesis, in order to understand the relationship between the two species. The research was carried out at the Ústřední hřbitov in Brno. Here, 10 infested and 10 uninfested lime trees were selected. During the summer of 2022, varnish impressions were taken from the leaves of lime and mistletoe trees and then all physiological parameters were measured. It was found that mistletoe infestation had almost no significant effect on both the morphology and physiology of lime tree leaves. Furthermore, it was shown that mistletoe has more smaller stomata than linden. It has been shown that although mistletoe has a higher stomatal conductance, the photosynthetic rate is the same for both species, thus the water use efficiency of mistletoe is much lower. It was confirmed that mistletoe, as a hemiparasite, has a much lower water potential than the host. Although this information helps to understand this interrelationship, it also results in further uncertainties worth to investigate in future.
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Otestování vlivu termínu aplikace růstových stimulátorů na efektivitu obrany dřevin vůči hemiparazitické rostlině jmelí bílé Viscum album L.
Javorský, David
This thesis focuses on finding the appropriate timing for the use of chemical defences to eradicate white mistletoe (Viscum album L.) using growth regulators designed for plant protection. The thesis is divided into two main parts, namely, the literature review related to the problem addressed and the practical implementation of the research. In the research, two growth regulators were applied in a regular interval of fourteen days between November and March. The results of this work, the showed effectiveness of the application of growth regulators used for mistletoe eradication in February. The efficacy of the two chemical agents used is different 73 % and 92 % over the entire period under study.
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Influence of avian Plasmodium on their hosts
Dulavová, Kristýna ; Svobodová, Milena (advisor) ; Vinkler, Michal (referee)
Avian malaria parasites of the genus Plasmodium are unicellular (and intracellular) protozoans of the group Haemospororida, using a blood-sucking insect (mosquito) as a vector and a bird as a vertebrate host. The effects of this disease, together with avian pox, have greatly influenced endemic populations of Hawaiian birds after introduction of a suitable vector to the islands by a human hand, leading to a drastic extinction of bird species; most of the remaining Hawaiian endemic species are now endangered. Apart from that, avian malaria is distributed nearly all over the world, infecting a variety of different hosts. This thesis is focused on the influence of avian malaria parasites mainly on their avian hosts. The most severe patologies caused by Plasmodium are associated with blood stages causing serious anemia in birds. More pathologies are connected with exoerythrocytic stages in the endothelial cells in various organs and are accompanied with external signs such as lethargy, respiratory distress, weakness, inappetence, sometimes weight loss and so on; different plasmodium species-bird host combinations have different outcomes. An interesting issue is the emerging tolerance against avian malaria in Hawaii Amakihi (Hemignathus virens), a species occupying low elevation areas of Hawaiian...
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Supply of Accommodation Services by Means of Shared Accommodation in the Tourist Region Česká Kanada (Bohemian Canada)
SVOBODOVÁ, Tereza
The diploma thesis is focused on shared accommodation in the tourist area of Czech Canada. The aim is to evaluate selected factors of competitiveness of the offer of shared accommodation services with regard to the location of tourism attractions and the offer of accommodation facilities. The data was obtained from the created Accommodation Database and the Airbnb portal. It was found out how many objects of shared accommodation are located in the tourist area of Czech Canada and analyzed their distance from the attractions of tourism against official accommodation. Selected competitiveness factors were evaluated first with respect to all objects and official accommodation facilities, and then within 20 kilometers of the selected attractions. The price was also analysed and the biggest perceived benefits of shared accommodation were identified. The outputs of the analyses and the own observation in the issue enabled the elaboration of proposals and recommendations leading to a possible increase in the competitiveness of shared accommodation in the Czech Canada tourist area.
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