BioProject

Sterols are essential nutrients for insects because, in contrast to mammals, no insect (or arthropod for that matter) can synthesize sterols de novo. More...

Sterols are essential nutrients for insects because, in contrast to mammals, no insect (or arthropod for that matter) can synthesize sterols de novo. Cholesterol is the most common sterol in insects, but it is not found in plants in large quantities; plant-feeding insects typically generate their cholesterol by metabolizing phytosterols. However, different plants species can contain different types of phytosterols, and some phytosterols are not readily converted to cholesterol. In this study we examined, using artificial diets containing single sterols, how typical (cholesterol and stigmasterol) and atypical (cholestanol and cholestanone) sterols/steroids affect the performance of a generalist caterpillar (Helicoverpa zea), restricting this analysis to midgut tissue because this is where sterol/steroid absorption occurs, and the midgut is the putative site of dietary sterol/steroid metabolism. In general, H. zea performed best on the cholesterol and stigmasterol treatments; performance was reduced on cholestanol, and was very poor on cholestanone. We compared the transcript profiles of larval guts in response to differentially suitable sterols, using the optimal sterol, cholesterol, as a control, using a two-color reference design microarray experiment. Midgut gene expression patterns differed between the treatments; relative to cholesterol, differences were lowest on the stigmasterol treatment, intermediate on the cholestanol treatment, and greatest on the cholestanone treatment. Overall design: Transcriptional profiling comparing Helicoverpa zea gut tissue from third instar larvae exposed to four different dietary sterols, namely Cholesterol (CON), Cholestanol (ChStanol), Cholestan-3-one (Ch3one) and Stigmasterol (Stigma). Two-color reference design. Biological replicates: 4 (5 individuals per replicate). 12 samples total. Less...