New multivariate image analysis method for detection of differences in chemical and structural composition of chitin structures in tardigrade feeding apparatuses
- 227 Downloads
The feeding apparatus of the eutardigrade Paramacrobiotus richtersi was examined with confocal laser scanning microscopy using three different wavelengths, taking advantage of the autofluorescence of the chitin present in its structures. The main goal was to test new method based on multivariate image analysis for detection of differences in the chemical and structural composition of chitin structures and the relationships between chemical structure and physical properties of feeding structures. The collected images were analyzed using factor analysis under the self-developed MATLAB-based software ImageA. It was possible to observe small differences in chitin composition using the variations (shifts) of emission spectra caused by differences in the microenvironment of chitin fluorophore. Images of feeding apparatuses within the body and discharged by the animal during molt were recorded applying three excitation/emission (ex/em) sets and then analyzed using factor analysis with three methods for rotation of factor scores (without rotation, with orthogonal rotation, and oblique rotation). With this procedure, it was proven that chitin organization in the feeding apparatus of tardigrades is not homogeneous, but changes according to the mechanical and structural requirements of the structures. Besides the new knowledge about the tardigrade feeding apparatus, ImageA was also proven to be reliable and applicable tool for various problems in the analysis of multispectral images, as autofluorescence images are generally considered as difficult to analyze due to the small initial set of input data and high correlation among the images observed at different ex/em wavelengths.
KeywordsBuccopharyngeal apparatus Chitin Factor analysis Paramacrobiotus richtersi Tardigrade
This paper was supported by short-term fellowship provided by Federation of European Biochemical Societies (FEBS) and project funded by Serbian Ministry of Education, Science and Technological Development III43010. The research is also part of the project “Environments, food and health” granted by the University of Modena and Reggio Emilia (Italy).
- Degma P, Bertolani R, Guidetti R (2015) Actual checklist of Tardigrada species, p 40. http://www.tardigrada.modena.unimo.it/miscellanea/Actual%20checklist%20of%20Tardigrada.pdf. Accessed 09 July 2015
- Guidetti R, Bertolani R (2005) Tardigrade taxonomy: an updated check list of the taxa and a list of characters used in their identification. Zootaxa 845:1–46Google Scholar
- Kahn E, Lizard G, Pélégrini M, Frouin F, Roignot P, Chardonnet Y, Di Paola R (1999) Four-dimensional factor analysis of confocal image sequences (4D-FAMIS) to detect and characterize low copy numbers of human papillomavirus DNA by FISH in HeLa and SiHa cells. J Microsc 193(3):227–243. doi: 10.1046/j.1365-2818.1999.00435.x CrossRefPubMedGoogle Scholar