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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.
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Juvenile hormone signaling in insect development and reproduction
SMÝKAL, Vlastimil
This thesis comprises three published papers and one manuscript, all focused on the role of juvenile hormone (JH), the JH receptor Methoprene-tolerant (Met) and its target gene Krüppel-homolog 1 (Kr-h1) in insect development and reproduction. The JH-Met-Kr-h1 pathway is critical for metamorphic transition in hemimetabolan Pyrrhocoris apterus (Hemiptera) and holometabolan Bombyx mori (Lepidoptera) but seems to be dispensable during early larval postembryonic development. The results also show that Met and its heterodimeric partner Taiman (Tai) but not Kr-h1 are critical for ovarian development and vitellogenesis in Pyrrhocoris females. In vitro, in vivo and cell-based techniques in Drosophila melanogaster have demonstrated that Met and its paralog Gce are a bona fide receptor for JH. Only Gce capable of binding JH rescued Drosophila deficient for Met and Gce proteins, and the capacity of Gce to bind JH was necessary for JH-dependent transcriptional activation by Gce and Tai.
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Role of Jun and Fos in oogenesis of the beetle \kur{Tribolium castaneum}
SMÝKAL, Vlastimil
The aim of this work was to examine the function of the nuclear effectors of JNK signaling, Jun and Fos, in insect telotrophic ovaries, and compare it to the polytrophic ovary of Drosophila. RNA interference knockdown of Jun and Fos in the beetle Tribolium castaneum blocked oogenesis by causing death of follicle cells during growth of the vitellogenic oocytes through caspase-dependent apoptosis. Jun and Fos are therefore required for follicle cell maintenance, which is not the case in Drosophila. Since knockdown of the Jun N-terminal kinase (JNK) had no such effect, Jun and Fos likely act downstream of another kinase during Tribolium oogenesis. We propose that Jun and Fos ensure follicle cell survival upon physical stretching of the follicle epithelium resulting from the oocyte growth.
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