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Reproductive strategy of the termite Silvestritermes minutus and its consequences for the life history and ecological succes
Křivánek, Jan ; Hanus, Robert (advisor) ; Klimeš, Petr (referee)
Mixed reproductive strategies are unique modes of reproduction, in which the organisms alternate sexual and asexual offspring production to benefit from both processes. In termites, such a strategy was first described in 2009 and dubbed Asexual Queen Succession (AQS). Reproduction in most termite species is based on a presence of one pair of long-lived reproductives, the primary king and queen, producing in a lifelong strict monogamy all other colony members using classical sexual processes. In a few rare species, the primary queen has been observed to be replaced at some stage of colony development by a harem of neotenic queens. These arise from unfertilized eggs via thelytokous parthenogenesis and reproduce with the founding king. While the workers, soldiers and winged dispersing reproductives remain to be produced sexually, new generations of parthenogenetic neotenic queens appear in the colony to supplement the harem. As long as the founding king is alive, the genetic constitution of most offspring remains identical as if the founding queen would still be alive, while the overall fecundity of the colony increases thanks to the large number of queens. At the same time, the continuous renewal of the harem by new parthenogens offers a virtually unlimited lifespan extension to the colony. In my...
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Use of comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection for metabolomic analysis of Gloeophyllum trabeum fungus
Kuchler, Ondřej ; Sobotníková, Jana (advisor) ; Kozlík, Petr (referee)
Fungus Gloeophyllum trabeum (Agaricomytes: Gloeophyllates) is a brown rot wood-decay fungus which produces a vast spectrum of volatile secondary metabolites. Scientific publications state, that one of the metabolites produced by G. trabeum, can be the substance (3Z,6Z,8E)-dodecatrien-1-ol. This chemical substance is also the main component of trail-following pheromone of Rhinotermitidae termite family. In this diploma thesis, I was trying to verify whether various species of G. trabeum are in fact capable of producing the substance (3Z,6Z,8E)-dodecatrien-1-ol. I was also focusing on the effects of saccharides, present in nutrient solutions, on quantitative and qualitative change in composition of volatile secondary metabolites produced by G. trabeum. The saccharides I used for my research were - maltose, fructose, sucrose, xylose, and mannose. The analysis was made by using comprehensive two-dimensional gas chromatography separation technique with time-of-flight mass spectrometric detection (GC×GC-TOFMS). During my research I discovered that one of obtained species of G. trabeum can produce substance (3Z,6Z,8E)-dodecatrien-1-ol, but only under specific conditions. It is produced when cultivating on Petri dishes on agar - cellulose growth media. The measurement was further validated by...
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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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Biological effects of substances isolated from Isoptera species
Dušková, Simona ; Hrstka, Miroslav (referee) ; Brázda, Václav (advisor)
This thesis was focused on monitoring the viability of eukaryotic and prokaryotic cells after exposure of termites-isolated chemicals. Recently, evidence of antibacterial and antifungal properties of these defense substances has grown, and they can find a wide range of uses not only in the pharmaceutical industry. In this work, three defensive substances from termites were studied: nerolidol, nitropentadecene and methylanthranilate. Their antibacterial effects, minimal inhibitory concentrations and minimal bactericidal concentrations against Escherichia coli STBL3 strain were monitored. Further, their cytotoxic effects on eukaryotic non-tumor (HEK293FT) and tumor cells (MCF7) as well as their effect on plasmid DNA were studied. Antibiotic ampicillin and cytostatic cisplatin were used as control substances for antibacterial and cytotoxic effects, respectively. In the case of the action of nerolidol, nitropentadecene and methylanthranilate on the STBL3 strain, antibacterial activity was not demonstrated. Cytotoxic effects were observed nerolidol and nitropentadecene. None of the examined substances modified the plasmid DNA.
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Prokaryotic symbionts of protists living in the intestine of wood eating cockroaches and termites
Kubánková, Aneta ; Hampl, Vladimír (advisor) ; Rotterová, Johana (referee)
Termites and wood-eating cockroaches are worldwide successful especially because of their ability to digest lignocellulose efficiently. After a long period of coevolution a complex ecosystem of diverse microorganisms was established in their hindgut. A lot of lineages of flagellates live solely within this unique environment and it is impossible to cultivate them in vitro. As termites are unable to survive without their eukaryotic endosymbionts, also protists are strongly linked to prokaryotes colonizing their cytoplasm and cytoplasmic membrane. Numerous phyla of bacteria participate in nitrogen fixation and efficient nitrogen utilization, synthesis of amino acids, cofactors and vitamines. Some of them take part in the degradation of lignocellulose. Representatives of another domain of prokaryotes, Archea, are important in the final stages of lignocellulose fermentation, because they utilize the produced hydrogen gas in a process of methanogenesis. Large part of our knowledge about the composition and function of the termite gut biota was acquired thanks to metagenomic studies.
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Analytical chemistry unravels the diversity and function of chemicals used for communication and defence in termite societies
Krasulová, Jana ; Bosáková, Zuzana (advisor) ; Pacáková, Věra (referee) ; Lapčík, Oldřich (referee)
Analytical chemistry plays a crucial role in studies on chemical ecology and only the development of sophisticated methods enables the detection of biologically active compounds that are usually present in minute quantities and often in very complex mixtures. My thesis is dedicated to the application of modern analytical techniques and instrumentation to unravel the identity, chemical diversity and function of semiochemicals and defensive compounds used by various species of termites. The first section of this thesis aims at the identity of chemicals used in communication, the pheromones. I studied the chemistry of the trail-following communication in three selected species of termites. Besides the identification of (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol, the most frequent termite trail-following pheromone, as the trail-following pheromone in Psammotermes hybostoma (Rhinotermitidae), I participated in the description of two new structures, (10Z,13Z)-nonadeca-10,13-dien-2-one in Glossotermes oculatus (Serritermitidae) and syn-4,6-dimethylundecan-1-ol in Hodotermopsis sjoestedti (Archotermopsidae). We identified (3Z,6Z,8E)-dodeca-3,6,8-trien-1-ol to be the female sex pheromone in Psammotermes hybostoma, and syn-4,6-dimethylundecanal to be the male sex pheromone in Hodotermopsis sjoestedti. I also...
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New case of mixed reproductive strategy and its adaptive significance in the neotropical termite Silvestritermes minutus (Termitidae: Syntermitinae)
Křivánek, Jan ; Hanus, Robert (advisor) ; Žďárek, Jan (referee)
Thanks to the progress in genetic methods in population ecology, many critical discoveries were recently made in the field of reproductive strategies of social insect. Among them is the description of mixed reproductive strategies, combining advantages of sexual reproduction with thelytokous parthenogenesis. The queens of such species produce sterile castes through classical sexual process from fertilized eggs, while future queens develop asexually from unfertilized eggs. This original breeding system was first described in several genera of ants, but it was found very recently, that it is not restricted to social Hymenoptera, since it has been identified also in the phylogenetically remote eusocial clade of termites. Switching between the sexual process and thelytokous parthenogenesis, now known as Asexual Queen Succession (AQS), which enables a continuity of genetically almost identical queen generations after the death of the founding primary queen, was first reported only in one genus of lower termites, i.e. Reticulitermes. Recently, our research group participated at the identification of AQS in four other species from two subfamilies in higher termites. One of these species is Silvestritermes minutus. This species is locally abundant in French Guiana and lives in small, well shaped nests on...
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Digestive proteases of termites
Čermáková, Markéta ; Konvalinka, Jan (advisor) ; Ryšlavá, Helena (referee)
Digestive proteolysis in termites has not been studied yet. In this diploma thesis, proteolytic enzymes of the digestive tract of two significant pest species Reticulitermes santonensis and Coptotermes formosanus (Rhinotermitidae) were analyzed. Proteases were identified and quantified in gut compartments using a panel of specific substrates and inhibitors. Major proteases were localized in the midgut and were classified as endogenous serine proteases of trypsin type. Minor cysteine proteases were detected in the paunch and were most likely produced by symbionts. The trypsin protease from R. santonensis was chromatographically isolated and its N-terminal sequence was identified. The physiological importance of the digestive trypsin proteases was demonstrated using selective inhibitors tested in vivo with C. formosanus. Based on the analysis of proteases from additional 12 termite species, a general scheme of digestive proteolysis in the order Isoptera was proposed. (In Czech)
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Specific behaviour of soldiers towards reproductives of termite genus Prorhinotermes (Isoptera: Rhinotermitidae).
Dolejšová, Klára ; Šobotník, Jan (advisor) ; Klimeš, Petr (referee)
Soldier caste is the oldest altruistic caste in termites, highly specialized for defensive tasks. Therefore, a number of adaptations in anatomy and behaviour can be observed in soldier, lacking in other termite castes. The aim of this study was to verify the hypothesis that in disturbed groups the soldiers will prefer to stand by and defend the reproductives, the most valuable individuals. Therefore, I studied in two species of the genus Prorhinotermes (P. simplex and P. canalifrons) the ability of soldiers to discriminate neotenic reproductives and provide them with defence. In agreement with the initial hypothesis, the soldiers of both species prooved to be able of an instantaneous recognition of reproductives and remained close to them. In P. simplex, the neotenic female was the most attractive individual, while in P. canalifrons, neotenics of both sexes were equally attractive. The observed preference of reproductives appears to occur only with a certain age of the reproductives in incipient colonies, along with their sexual maturation. Caste specificity of cuticular lipids supports the presumption that the caste recognition is based on olphactoric cues in the cuticle of reproductives.
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