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Ontogeny of exaggerated structures in dung beetles (Coleoptera: Scarabaeinae)
Žídek, Radim ; Šípek, Petr (advisor) ; Hanus, Robert (referee)
E n g l i s h a b s t r a c t Horns of scarab beetles represent a secondary sexual characters present mostly in males, to whom they serve as weapons in combats over the acces to females. In many species, two discrete male forms occur, "horned" and "hornless", which employ different reproductive strategies. Adult body size and horn morphology are determined by nutritional conditions encountered by larvae during their development. Switching between developmental pathways is accomplished by circulating levels of juvenile hormone (JH) which reflect body size, and genetically determined threshold of sensitivity to it. When body size is larger then threshold, horn growth occur, whereas if it's not, a brief pulse of ecdysone reprogramme the development and hornless adult emerge. Reprogramming the development encompass modifications of the insulin receptor pathway as well as changes in exact domains of genes expression envolved in specifying the proximodistal axis of the developing horn. Development of horns is morphologically reminiscent that of other insect appendages, with which it shares the expression of genes wingless, decapentaplegic, Distal-less, dachshund, homothorax, aristaless and EGFR, parts of gene regulatory network ensuring origin of the outgrowth of the cuticle. Some of them are expressed through...
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Physiological basis of extended longevity in termite kings and queens - is activation of telomerase mechanism linked with extended longevity of termites?
Pangrácová, Marie ; Hanus, Robert (advisor) ; Kodrík, Dalibor (referee)
- Extended longevity and high fecundity are two phenomena typical for reproductive castes (queens, eventually kings) of eusocial insects. In my thesis, we explore the hypothesis that the longevity of reproductives in the termite Prorhinotermes simplex is linked with the activation of the telomerase enzyme complex. Telomerase is well known for its life-extension functions, due especially to its capacity to prolong the telomeric ends of chromosomes. Therefore, we studied here the gene expression of: (1) the gene TERT coding for the catalytic subunit of the telomerase and (2) the genes of the main endocrine regulatory pathways, known to be responsible for the control of reproduction and longevity in insects. Expression dynamics of these genes were measured in sterile and reproductive castes of P. simplex during their development and sexual maturation. Based on our results obtained from the TERT expression analyses and their comparison with telomerase enzyme activities, we assume that the telomerase action in the long-lived reproductive individuals is regulated at a post-transcription level. Furthermore, we observed in reproductive castes a simultaneous upregulation of some transcription variants of vitellogenin and the genes for insulin signalling pathways. We can, therefore, conclude that in...
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The role of male external glands in sexual behaviour of insect
Dvořák, Tomáš ; Kotyková Varadínová, Zuzana (advisor) ; Hanus, Robert (referee)
The body of some insect's males is covered by glands, which females are interested in during or after courtship and copulation. Female can palpate this glands or feed on their secretion. My bachelor thesis describes these glands in five orders of insect, where they are known: Zygentoma, Zoraptera, Coleoptera and especially Orthoptera and Blattodea. In the introduction i describe briefly their histology, morphology and ontogeny. But the main part of the work deal with their ethological and ecological function. This glands have four main functions. They can serve to maneuver female into proper position and allow the male to clasp her genitalia. Another function is prolonging of copulation, which enable the male to transfer more sperm. Glands can also provide nutritious secret, through it the male directly affects the female fitness. The last function is simple signal of male quality, which through the production of secret demonstrates his good condition. The role of the glands is often uncertain and their functions are often overlaping.
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Evolution of sensitivity to trail-following pheromones in termites
Száková, Barbora ; Hanus, Robert (advisor) ; Sillam-Dussès, David (referee)
Eusocial insects evolved a sophisticated intraspecific communication, dominated by chemical signals, the pheromones. Termites (Isoptera) represent an excellent example in this respect, having a wide range of pheromones, such as trail-following, sex-pairing, alarm, and other pheromones. It is especially the former category of pheromones which is ubiquitous in termites and which was chemically characterized in many taxa across termite phylogeny. This allowed phylogenetic reconstruction of the chemical diversity of trail- following pheromones and calls for searching of evolutionary patterns of the sensitivity to these pheromones in various lineages across the tree of life, including the search for evolutionary scenario of the emergence of specific olfactory receptor proteins. In most species, the trail-following pheromones are represented by mono-, di- and tri-unsaturated fatty alcohols (3Z)-dodec-3-en-1-ol (DE), (3Z,6Z)-dodeca-3,6-dien-1-ol (DDE), and (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol (DTE). My overall aim in this thesis was to contribute to the understanding of the evolution of olfactory detection of C12 fatty alcohol trail-following pheromones in termites. More specifically, my question was whether evolutionarily more basal clades (Kalotermes flavicollis and Neotermes cubanus from the family...
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Methods of insect body and food marking and their utilization in bees (Anthophila)
Macháčková, Lenka ; Straka, Jakub (advisor) ; Bogusch, Petr (referee) ; Hanus, Robert (referee)
Marking methods represent often an essential part of many studies which target on insect biology. These marking techniques sometimes represent the only possible way to obtain new and important informations. In the first part of the thesis I deal with individual insect labeling, which was used for marking of solitary bees and their nests as a tool of obtaining informations about nesting bee dynamics in aggregation. Our study show that nest owner replacements are very common in all four species. However, a large percentage of the nests were abandoned by the female owners before owner change. Only a part of all the nests were trully usurped on the nesting site. The true usurpations thus represent rather minor part of observed nest owner replacement situations. The bees surprisingly often abandon their nests and found the new ones. The frequent contacts of the females on a nesting site occur as a result of common nest owner replacements. High tolerance of bees to each other together with tolerance of usurpations and low level of aggression may thus represent one of the possible ways towards communality and other types of social behaviour. In the second part of the thesis I focus on the possibilities of food marking in bees. Effectivity of sugar and pollen utilization are not yet fully understood in...
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Advanced Driving System Of The Three-Phase Dc Motor
Hanuš, Radek
The presented article briefly outlines a field-oriented control algorithm used to drive a permanent magnet three-phase DC motor with efficiency maximization and its modification to reduce overall computational complexity. This enables the utilization of the algorithm in computer constrained devices, for example in a self-balancing vehicle, which the algorithm and electronics were previously designed for.
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Characteristics of garnets from the locality Dolní Olešnice and problematics of their source rocks
Jaroměřský, Štěpán ; Matějka, Dobroslav (advisor) ; Hanus, Radek (referee)
Pyrope is one of the representatives of the garnet supergroup, which are known for their use in jewellery and have a rich history in the Czech Republic. However, despite their long-term use, a part of the supergroup is still unexplored and the source rock is unclear at some localities, which makes it difficult to explain the development of the deposit and the formation of surrounding geological units. This bachelor thesis describes pyrope as a Czech garnet and summarizes views on the issue of its primary source rock in the Czech Republic. This thesis also deals with characterizing of pyropes from the locality of Dolní Olešnice and discusses their primary source rock, the geological situation of the surrounding area, the method of mining and the minerals of the heavy fraction. Based on the study of available literature, a wealth of information about the pyropes from Dolní Olešnice was gathered, which could be the basis for further more detailed research of the area and the localisation of the pyrope source rock here. A geochemical heavy minerals prospecting was also carried out on the site to assess the quality of the pyrope drifting ability for several recommended flows in the area. Key words: garnets, garnet supergroup, pyrope, Dolní Olešnice, Podkrkonoší, mining, geochemical heavy minerals...
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Cell senescence with a focus on telomerase theory
Laštůvková, Viktorie ; Tlapáková, Tereza (advisor) ; Hanus, Robert (referee)
Cell senescence is an irreversible state in which the cell cycle ends. The cell remains metabolically active, but its physiological functions are limited. Cell cycle arrest is a response to the action of a number of factors, most of which affect the secondary structure of DNA in various ways and cause damage to it. Other initiators of cell entry into the senescent state are oncogenes and chemotherapeutics. One of the best studied factors, which is also in a way the "fairest", is the shortening of the telomere. Telomeres are non-coding regions of DNA at the chromosome ends that shorten slightly with each division of the cell. If the cell does not have mechanisms to compensate for this loss, the Hayflick limit is reached after a certain time. In general, senescence can be considered as a protective mechanism to prevent DNA damage pathologies. However, the presence of senescent cells in tissues is often ambivalent, accumulates with age, and can cause many degenerative diseases. The senescent phenotype includes a wide range of signs such as changes in cell size and shape, increased granularity, or altered range of expressed genes. A significant phenomenon of senescent cells is the secretion of biologically active factors contributing to physiological or pathological changes in the organism. Key words:...
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Advanced driving system of the three-phase DC motor
Hanuš, Radek ; Boušek, Jaroslav (referee) ; Háze, Jiří (advisor)
The main aim of this thesis is to design and develop a control unit for a three-phase direct current motor that will be able to maximize its efficiency. To accomplish this request a field oriented control combined with modified phase driving signals is used. The emphasis is put on the creation of a simple and unique solution as well as the ability to use this device in the single wheel wehicle, which previous bachelor thesis was focused on. The first part of this thesis lists some of commercially available and do-it-yourself solutions together with their attributes. The next part describes target motors and different options of how to control them. The third part focuses on the field oriented control, its individual parts and features, as well as the final solution. And finally the realization of the electrical part, firmware, PC application and necessary settings are described at the very end of the thesis.
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