|
|
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...
|
|
|
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.
|
|
|
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.
|
|
|
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...
|
|
|
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...
|
|
| |
|
|
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)
|
|
|
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.
|
|
|
Biology and evolution of termite genus Neocapritermes (Blattodea: Termitoidea: Termitidae: Termitinae)
Cintulová, Eliška ; Šobotník, Jan (advisor) ; Jakub, Jakub (referee)
My thesis is a brief summary of knowledge on termites, especially genus Neocapritermes. It describes ecology, nutrition, caste patterns and phylogenetics of termites. In detail, it characterizes Neocapritermes taracua, its ecology and defensive behaviour of workers. The main topic is formulation of phylogenetic hypothesis concerning position of genus Neocapritermes and relatedness among particular species of the genus. My results suggest that Planicapritermes and Dentispicotermes are the closest relatives of Neocapritermes, perhaps inner taxa located within the genus.
|
|
|
Evolutionary Ecology of Termites
Stiblík, Petr ; Šobotník, Jan (advisor)
Termites are one of the most important ecological factors on Earth. By right, they are called ecosystem engineers. They influence their habitat by very complex ways - recycling of plant tissues, aerating soil, transporting huge amounts of organic matter. Thanks to their ability decompose up to 100% of local production of celulose and lignin, they are responsible for termination of coal origination. Their ecological and evolutionary succsess is based on organization of their eusocial community into several different castes. Precize distribution of tasks between castes is one of the crucial factors of evolutionary success of termites. It is the undertanding of their ontogeny and colony organization what is key to effective fight against pest species and, on the opposite, the key to effective help to those species important for decomposing and transport of organic matter in soil.
|
guest ::
