Three-dimensional structure of elastin from Caspian White Fish (Rutilus frisii kutum) skin/swim bladder by Scanning Electron Microscopy (SEM)
Three-dimensional structure of elastin from Caspian White Fish (Rutilus frisii kutum) skin/swim bladder by Scanning Electron Microscopy (SEM)
Rezvan Mousavi-Nadushan,1,*Naghmeh Roohi-Shalmaee,2Milad Mahmoodi Kelarijani,3
1. Department of Marine Science, Faculty of Natural Resources and Environment, Tehran North Branch, Islamic Azad University, Tehran, Iran. 2. Venom and Biotherapeutics Molecules Lab., Medical Biotechnology Department, Biotechnology Research Center, Pasteur Institute of Iran. Tehran, Iran. 3. Department of food science and technology, North Tehran Branch, Islamic Azad University, Tehran, Iran
Introduction: In recent years, biomaterials have attracted more and more attention due to particular macromolecular structure. They have practical applications in the pharmacy, tissue engineering, cosmetics and food industries. One of these supramolecular biopolymers is elastin. Elastin is one of the structural proteins dispersed in most connective tissues all over the body. This protein, in connections with microfibrils forms fibers and sheets, which are considered to provide appropriate elasticity to tissues of the organs. It is therefore essential to understand accurately the association of the elastin constituents in relation to the mechanical properties. So Scanning electron microscopy (SEM) is valuable for indicating the three-dimensional construction of the elastin constituents.
The present study, therefore, firstly evidences the applicability of the organic acid hydrolysis and hot alkali methods to SEM studies of skin/swim bladder of Caspian White Fish (Rutilus frisii kutum), secondly shows the ultrastructure of elastin components treated with these two methods.
Methods: Extraction: Elastin was obtained from skin and swim bladder of CWF. Soluble and insoluble skin/swim bladder elastin were obtained by extraction of minced/defatted tissues with 0.02 M formic acid and 0.1 M NaOH, respectively.
Scanning Electron Microscopy (SEM): The soluble and insoluble Elastin fibers from skin and swim bladder of Caspian White Fish (Rutilus frisii kutum) were observed by (SEM) Scanning Electron Microscope (SNE4500M, South korea).
Results: Scanning Electron Microscopy images of insoluble Elastin extracted from skin
The surface topography and morphology of the insoluble Elastin extracted from skin were analyzed by scanning electron microscopy (SEM). At higher magnification the elastic fibers and β-sheets are detectable.
Scanning Electron Microscopy images of soluble Elastin from skin
The surface topography and morphology of the soluble elastin extracted from skin showed micro fibrils on the periphery of the elastic fibers supposed to help the structure of the fibers and support in elastin crosslinking.
Scanning Electron Microscopy images of soluble Elastin extracted from swim bladder
Based on the images at higher magnification the spherical aggregates/ coacervate spherules established during coacervation in soluble elastin from swim bladder, are evident.
Scanning Electron Microscopy images of insoluble Elastin from swim bladder
In the pictures of insoluble Elastin from swim bladder, micro fibrils on the periphery of the elastin, organized into small bundles are obvious.
Conclusion: SEM images presented the fiber-like structure for soluble/insoluble elastin from skin and insoluble elastin from swim bladder with micro fibrilar sheaths and different coalescence and agglomeration conformation and multiple globular elastin spherules for soluble elastin from swim bladder. The present study has demonstrated that elastin constituents are mainly comprised of thinner fibrils. These fibrils are present alone or in bundles, so creating elastin fibrils. Elastic fibers develop through the coalescence and combination of similar elastin fibrils. We therefore consider the soluble and insoluble fibrils extracted from skin and insoluble elastin from swim bladder to be a structural component of elastin which produces sheets or branched fibers of different sizes.
In conclusion, elastin from CWF presented fibrilar bundles with different diameters and peripheral stable beta sheets, such stability of secondary structure are appropriate feature for biopolymer designs like scaffolds and biomaterials.