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Hormonálně řízená obrana proti hmyzím patogenům
BODLÁKOVÁ, Karolina
The aim of this bachelor thesis was to characterize the effect of one insect pathogen (entomopathogenic nematode Steinernema carpocapsae) and one venom (from the honey bee Apis mellifera) on digestive enzymes (amylases, proteases, lipases), and on adipokinetic hormone production in the brain of the cockroach Periplaneta americana . The experiments were done with the adult male and female cockroaches from a colony kept in the Insectary in the Institute of Entomology BC CAS. The pathogen/venom were applied into the cockroach body by injection 24 hours before the processing. After that the activity of digestive enzymes in the midgut, and AKH level in the brain were monitored. The results showed that the nematode has no effect on enzymes, and on AKH level as well. On the other hand, the bee venom partially increased the activity of digestive enzymes, but the role of AKH in this process in not completely clear.
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Ověření souvislosti genů \kur{enol-1} a \kur{astacinu} s evoluční adaptací na parazitismus u druhu \kur{Heterorhabditis bacteriophora}
HARTMANN, Jan
This thesis was focused on the verification wheter the two candidate genes, enol-1 and astacin metalloprotease, are linked to the parasitic adaptation of Heterorhabditis bacteriophora. While the expression analysis and knock-down of those genes by RNAi did not corroborate thwe hypothesis, biostatistical evolutionary analysis of orthologs from 25 nematode species across clades III, IV and V found several footprints of episodic diversifying selection. However, none of this was strictly linked to the parasitic species. Since the prevailing detected selection was purifying, both candidate genes are more likely conserved and not directly shaped by adaptation to parasitism.
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Study of adipokinetic hormone role in insects stressed by entomopathogenic nematodes
IBRAHIM, Emad Ahmed Sayed
In this thesis, the effect of infection elicited by entomopathogenic nematodes (EPNs) Steinernema carpocapsae on Pyrrhocoris apterus and Drosophila melanogaster models were evaluated, and a role of adipokinetic hormones (AKHs) during the infection was characterized. These were monitored by determination of mortality, and various biochemical and physiological characteristics such as AKH levels both in the central nervous system (CNS) and in hemolymph, AKH gene expression in CNS, level of anti-oxidative stress markers, general metabolism and level of nutrients in normal and genetically modified insects. At P. apterus the mortality tests revealed that application of AKH increases the efficacy of EPN treatment. This result was confirmed using the firebugs with AKH receptor deficiency. Further, the increase of AKH expression and AKH levels in CNS and hemolymph seemed to be coordinated after the nematode treatment. At the D. melanogaster model also, the effect of adenosine into the above-mentioned characteristics was included. For this, mutants in AKH (AHK1), adenosine receptor (AdoR1) genes, and in both these genes together (AHK1 AdoR1 double mutant) were employed. Altogether, the results confirmed the involvement of AKH, and partially also adenosine into the antistress defense reactions elicited by the nematobacterial infection. Finally, the last part of the study was focused on examination of the vitellogenin (Vg) role in the defense reaction in firebug body P. apterus affected by two entomopathogenic organisms, the nematode S. carpocapsae and the fungus Isaria fumosorosea. The results revealed that Vg proteins play an important role in the defense against both types of the infections and are also able to kill entomopathogenic bacteria Xenorhabdus nematophila, that are symbionts of S. carpocapsae and that increase toxicity of this nematode.
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