<p>Insects encounter many microorganisms in nature and to survive they have developed counter measures against the invading pathogens. In <i>Drosophila melanogaster</i> research on insect immunity has mainly been focused on infections by bacteria and fungi. We have explored the immune response against natural infections of the parasite <i>Octosporea muscaedomesticae</i> and the <i>Drosophila</i> C virus as compared to natural infections of bacteria and fungi. By using Affymetrix <i>Drosophila</i> GeneChips, we were able to obtain 48 genes uniquely induced after parasitic infection. It was also clearly shown that natural infections led to different results than when injecting the pathogens. </p><p>In order to search for the ultimate role of the lepidopteran protein hemolin, we used RNA interference (RNAi). We could show that injection of double stranded RNA (dsRNA) of <i>Hemolin</i> in pupae of <i>Hyalophora cecropia</i> led to embryonic malformation and lethality and that there was a sex specific difference. We continued the RNAi investigation of hemolin in another lepidopteran species, <i>Antheraea pernyi</i>, and discovered that hemolin was induced by dsRNA<i> per se</i>. A similar induction of hemolin was seen after infection with baculovirus and we therefore performed <i>in vivo</i> experiments on baculovirus infected pupae. We could show that a low dose of ds<i>Hemolin</i> prolonged the period before the <i>A. pernyi</i> pupae showed any symptoms of infection, while a high dose led to a more rapid onset of symptoms. By performing <i>in silico</i> analysis of the hemolin sequence from <i>A. pernyi</i> in comparison with other<i> Hemolin</i> sequences, it was possible to select a number of sites that either by being strongly conserved or variable could be important targets for future studies of hemolin function.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:su-224 |
| Date | January 2004 |
| Creators | Terenius, Olle |
| Publisher | Stockholm University, Department of Genetics, Microbiology and Toxicology, Stockholm : Institutionen för genetik, mikrobiologi och toxikologi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, comprehensive summary, text |
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