Odsevne mikrostrukture na površini enakonožca vrste Porcellionides pruinosus

Gantar, Ivana (author), Vittori, Miloš (mentor)

Kopenski enakonožci so posebneži med raki, ker so osvojili raznolike kopenske habitate. Od vodnih enakonožcev se razlikujejo po veliki raznolikosti struktur, ki jih najdemo na njihovi dorzalni kutikuli. Enakonožca vrste Porcellionides pruinosus prekrivajo okrogle mikrostrukture, ki mu dajejo bel poprh. Namen te naloge je bil raziskati strukturo, sestavo, optične lastnosti in nastanek teh okroglih mikrostruktur. Z uporabo različnih mikroskopskih tehnik smo vizualizirali površino kutikule tergitov pereona. Sestavo smo ugotavljali s histološkimi barvanji in inkubiranjem tergitov v kemikalijah ter slikanjem z vrstično elektronsko mikroskopijo (SEM). Lomni količnik krogel smo določili z imerzijo tergitov v snovi z različnimi lomnimi količniki in opazovanjem s faznim kontrastom in diferencialno interferenčnim kontrastom (DIC). Nastanek krogel smo proučevali med levitvenim ciklom, pri čemer smo z DIC, fluorescenčno mikroskopijo, SEM in presevno elektronsko mikroskopijo (TEM) analizirali tvorbo kutikule in kutikularnih struktur. Ugotovili smo, da krogle sestavljajo bazične makromolekule, najverjetneje polisaharidi ali glikozilirani proteini. Krogle so brezbarvne, z lomnim količnikom 1,53, ki je podoben lomnemu količnikom stekla in imajo strukturirano površino. Krogle nastanejo v fazi predlevitve, v obdobju ko nastaja tudi epikutikula. Epidermalne celice tvorijo izbokline, ki izločajo elektronsko gosto snov, ki bi lahko predstavljala gradnike krogel. Notranjost krogel ni homogena in se spremeni, ko se povezava krogel preko peclja z epidermalnimi celicami prekine. Evolucijska prednost teh struktur je še vedno uganka.

• Language: Slovenian
• Keywords: raki, enakonožci, kutikula, levitev, mikroskopija
• Work type: Master's thesis/paper
• Organization: BF - Biotechnical Faculty
• Year: 2019
• PID: 20.500.12556/RUL-111722
• COBISS.SI-ID: 5328975
• Publication date in RUL: 11.10.2019

Secondary language

• Language: English
• Title: Reflective microstructures on the surface of the isopod Porcellionides pruinosus

Abstract

Terrestrial isopods are unique among crustaceans, having conquered diverse terrestrial habitats. Comparing to aquatic isopods, they have a great variety of structures on their dorsal cuticle. Isopods Porcellionides pruinosus are covered with spherical microstructures that give this species a frosted look. The purpose of this master thesis was to determine the structure, composition, optical properties and mechanism of formation of these spherical microstructures. Using a variety of microscopy techniques, we were able to visualize the cuticle surface of pereon tergites. The composition of spheres was determined with histological stains and comparison of tergites treated with chemicals using scanning electron microscopy (SEM). The refractive index of the spheres was determined by the immersion of tergites in chemicals with different refractive indices and observing them with phase contrast and differential interference contrast (DIC). The formation of spheres was studied during the moult cycle and the formation of the cuticle and cuticular structures were observed with DIC, fluorescent microscopy, SEM and transmission electron microscopy (TEM). The spheres were found to be composed of basic macromolecules, most likely polysaccharides or glycosylated proteins. The spheres are transparent with structured surface and have a refractive index of 1.53, which is similar to the refractive index of glass. The spheres are formed in the premolt phase, when the epicuticle is generally formed. The epidermal cells form cell extensions that secrete electron-dense substance that could represent the building blocks of spheres. The spheres are not homogeneously composed and change their appearance when the connection with epidermal cells via stems is broken. The evolutionary advantage of these structures is still unknown.

• Keywords: crabs, isopods, cuticle, ecdysis, microscopy