title: The microstructures of biomineralized surfaces: a spectroscopic study on the exoskeletons of fresh water (Apple) snail, Pila globosa.
abstract: In view of the importance in understanding biomineralization processes in different molluskan species, the common fresh water apple snail Pila globosa in Indian origin was taken to explore its mineralized exoskeleton structures. The detailed structural studies of the exoskeletons of P. globosa have been undertaken. The isolated layers present in these shells were studied by electron paramagnetic resonance (EPR), optical absorption, and infrared spectral techniques. The EPR spectra of the organic protein layer periostracum show the characteristic signals corresponding to Fe(3+) ions at g = 4.1 and 2.0. The EPR spectra of the ostracum (middle) layer at room temperature gives a complicated spectrum consisting of a number of Mn(2+) signals of at least three sets due to the aragonite nature of the material. The results indicate the presence of the multivalent manganese ions, which undergo the redox mechanisms. The thermal variation of the EPR spectra show marked effect on these samples both in g-values and the basic spectral pattern.
authors.affiliation: Department of Physics, Sri Krishnadevaraya University, Anantapur 515 003, India.
authors.forename: C P Lakshmi
authors.initials: CP
authors.lastname: Prasuna
authors.forename: K V
authors.initials: KV
authors.lastname: Narasimhulu
authors.forename: N O
authors.initials: NO
authors.lastname: Gopal
authors.forename: J Lakshmana
authors.initials: JL
authors.lastname: Rao
authors.forename: T V R K
authors.initials: TV
authors.lastname: Rao
mesh_terms: D000818:Animals; D002119:Calcium Carbonate / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005720:Gamma Rays; D012908:Snails / Q000737:chemistry* / Q000528:radiation effects; D013055:Spectrophotometry, Infrared
chemical_list: D002119:Calcium Carbonate