|
|
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.
|
|
|
Evolution, Function and Chemical Diversity of Queen Pheromones in Social Insects
Kašparová, Kateřina ; Hanus, Robert (advisor) ; Urbanová, Klára (referee)
Societies of eusocial insects are probably the most complex biological systems. Repeated independent evolution of eusocial organization in multiple insect lineages has typically led to an unprecedented ecological success of these insects. However, beside coordinated work activities and altruism, the eusocial societies are also characterized by a potential for conflict over reproduction, leading to the evolution of mechanisms that prevent this conflict and ensure the colony homeostasis. Though it has long been known that this role is mediated by Queen Pheromones, there is still an important knowledge gap between our understanding of the biological role of Queen Pheromones and their chemical identity, biosynthesis and perception. Although the first Queen Pheromone has been identified in the early 1960s, more intensive research in this area is the matter of the last decade. The best known Queen Pheromone is that of the honey bee, contrasting with the knowledge on other social Hymenoptera and termites. Elucidating the chemical nature of Queen Pheromones could help to a better understanding of the evolution of social insects, their life cycle and community organization. This thesis summarizes the knowledge about the evolution and chemistry of Queen Pheromones in social insects.
|
|
|
Application of RNA interference to studies on biology of termites
Žalmanová, Anna ; Hanus, Robert (advisor) ; Smýkal, Vlastimil (referee)
The RNA interference (RNAi) mechanism can be used to reduce the expression of a selected gene in an organism. This method, discovered in 1998, has become the "gold standard" in basic biological research with overlaps to applied research and gene therapy in human medicine. For many reasons, RNAi is a suitable tool for the studies on biology of insects. RNAi is endowed with high sequence specificity, low costs, and easy application also in non-model species. Termites (Isoptera) are very sensitive to RNAi and this method is widely used to understand their physiology and ontogeny. The use of RNAi also has a potential in applied termite research and a significant number of publications have focused on the development of RNAi techniques as non-chemical pesticides against economically important termite species. This bachelor thesis aims to give a broad overview of the existing research on termites that uses the RNAi method.
|
|
|
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...
|
|
|
The effect of tropical land use change on soil-dwelling ants and termites, their interaction and on ecosystem processes they affect
TŮMA, Jiří
In this thesis I explore the role of tropical soil-dwelling ants and termites in driving ecosystem processes, their mutual interaction and their responses to tropical land use change. To do this I use a combination of methods, including a full review of the ant-termite interaction literature, field sampling for ants and termites, DNA barcoding-based inference of ant predation on termites, and creation and implementation of a new protocol for measuring terrestrial bioturbation. I found that the literature mainly documents anecdotal observations of interactions between ants and termites, the vast majority of which are predatory. Many of these appear to be opportunistic predation of termites by non-specific ants, although some ant species have developed sophisticated methods that enable them to specialise on termite predation. My field sampling demonstrated that soil ants and termites are susceptible to habitat degradation, with logging having minimal impacts, but conversion to oil palm affecting both groups to a greater extent. The predation rate of ants on termites differs between ant taxa, but seems to be stable across habitats. Finally, termites are important for soil bioturbation in all habitat types, but overall, this ecosystem function relies only on few species in oil palm plantations, raising concerns about susceptibility of this function to future extinctions. My work emphasizes the importance of maintaining the diversity of these two trophically linked groups for the ecosystem functions they provide.
|
|
|
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)
|
|
|
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...
|
|
|
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.
|
|
|
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...
|
|
|
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...
|
guest ::
