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The effect of viral infection on glycosidases activity in tobacco plants (Nicotiana tabacum L.)
Kloudová, Kateřina ; Ryšlavá, Helena (advisor) ; Tichá, Marie (referee)
Glycosidases are widely distributed among microorganisms and fungi, in plants and animals, too. They belong to the hydrolase class, which means that they hydrolyze glycosidic linkages in oligosacharides, polysacharides and other glycokonjugates, as for example glycoproteins, glycolipids or some alkaloids. The role of plant glycosidases has not been made clear till now, so that it is a subject of many studies as well as their characterization. The studied functions are the role during seed germination, during fruit ripening and softening and in defence against biotic and abiotic stress, too. Under biotic-stress, plants synthesize so-called pathogenesis-related proteins (PRP). It was found out that chitinases and β-1,3-glucanaces, which are endoglycosidases, act as PRPs in tobacco leaves. The goal of my work was to find out whether exoglycosidases (α- galactosidase, β-galactosidase, α-glucosidase, β-glucosidase, β-hexosaminidase and α- mannosidase) can also act in defence against biotic stress. I studied the effect of infection in tobacco (Nicotiana tabacum L. cv. Petit Havana SR1) leaves caused by Potato virus Y (PVY) on glycosidases activity. I examined the activity in control and infected tobacco leaves, in both cases the activity of soluble and membrane associated glycosidases was examined. I...
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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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