Characteristics of corneal lens chitin in dragonfly compound eyes.
Chitin in the compound eyes of arthropods serves as a part of the visual system. The quality of chitin in such highly specialised body parts deserves more detailed examination. Chitin in the corneal (ommatidial) lenses of dragonfly (Sympetrum fonscolombii) compound eyes was isolated by using the classical chemical method. The chitin content of the corneal lenses was determined to be quite high (20.3±0.85%). The FT-IR analysis showed that corneal lens chitin was in the α-form as found in all arthropod species where mechanical strength is required. The surface morphology analysis by scanning electron microscopy revealed that the outer part of corneal lenses consisted of long chitin fibrils with regular arrays of papillary structures while the smoother inner part had concentric lamellated chitin formation with shorter chitin nanofibrils. Chitinase enzymatic digestion studies, elemental analysis results and the degree of acetylation value showed the purity of chitin samples from corneal lens. The maximum degradation temperature value of the corneal lens chitin was observed at 369.2°C. X-ray analysis revealed that corneal lens chitin has high crystallinity index; 96.4%. Identification of chitin found in ommaditia of insect compound eyes can provide insights into insect vision and chitin-based optical material design studies.
Department of Biotechnology and Molecular Biology, Faculty of Science and Letters, Aksaray University, 68100 Aksaray, Turkey. Electronic address: muratkaya3806@yahoo.com.
Murat
M
Kaya
Department of Chemistry, Faculty of Science, Selcuk University, 42075 Konya, Turkey.
Idris
I
Sargin
Department of Biotechnology and Molecular Biology, Faculty of Science and Letters, Aksaray University, 68100 Aksaray, Turkey.
Ivan
I
Al-Jaf
Fisheries Programme, Keşan Vocational College, Trakya University, 22800 Keşan, Edirne, Turkey.
Sevil
S
Erdogan
Selcuk University, Faculty of Science, Department of Biochemistry, 42075 Konya, Turkey.
Gulsin
G
Arslan
D000818:Animals; D002686:Chitin / Q000032:analysis* / Q000648:ultrastructure; D002688:Chitinases / Q000378:metabolism; D054910:Compound Eye, Arthropod / Q000737:chemistry* / Q000166:cytology / Q000648:ultrastructure; D003315:Cornea / Q000737:chemistry* / Q000648:ultrastructure; D003460:Crystallization; D006868:Hydrolysis; D007908:Lens, Crystalline / Q000737:chemistry* / Q000648:ultrastructure; D063191:Odonata / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014961:X-Ray Diffraction
D002686:Chitin; D002688:Chitinases
Compound eyes; Insect vision; Ommatidium