Izgradnja in preoblikovanje celičnih stikov v ektodermalnih in endodermalnih epitelih členonožcev med razvojem

Kunčič, Katja (author), Žnidaršič, Nada (mentor), Mrak, Polona (comentor)

Medcelični stiki so dinamični kompleksi, ključni za organizacijo epitelov in selektivno prepustnost. Pri členonožcih mehansko stabilnost zagotavljajo predvsem adherentni stiki, selektivno prepustno bariero za paracelularne transporte pa septirani stiki (SS). Raziskali smo ultrastrukturne značilnosti subapikalnih adherentnih stikov in SS v epidermisu, črevesu in prebavnih žlezah členonožca Porcellio scaber (Crustacea: Isopoda). Opredelili smo preoblikovanje ultrastrukturne zgradbe stikov med levitvijo ter diferenciacijo in preoblikovanje stikov med embrionalnim in postembrionalnim razvojem. Z mikroračunalniško tomografijo smo prikazali morfogenezo organov prebavnega sistema v kontekstu celotnega organizma ter s komplementarno analizo histološke organizacije epitelov ter morfometrične analize celic in medceličnih stikov na ultrastrukturni ravni opredelili strukturne spremembe med razvojem na vseh navedenih nivojih biološke organizacije. Pokazali smo, da je ultrastruktura subapikalnih adherentnih stikov podobna v vseh preučevanih ektodermalnih epitelih in analiziranih razvojnih fazah, nasprotno pa se ultrastruktura SS razlikuje glede na funkcijo epitela. Diferenciacija SS je postopna, nagubani SS, ki so značilni za ektodermalne epitele, prehajajo iz krajših v daljše nize sept in se med levitvijo intenzivno preoblikujejo in skrajšajo. Gladki SS v endodermalnih epitelih so ultrastrukturno diferencirani že v srednji embrionalni fazi in se med razvojem organizma predvsem podaljšujejo. Primerjava z Drosophila suzukii je pokazala razlike v strukturi gladkih SS, ki so v endodermalnem epitelu prebavnih žlez P. scaber neprekinjeni in potekajo ravno, v endodermalnem epitelu srednjega črevesa D. suzukii pa so lahko prekinjeni, zaviti in obsežnejši.

• Language: Slovenian
• Keywords: adherentni stiki, kopenski rak enakonožec, levitev, morfogeneza, mikro-CT, Porcellio scaber, septirani stiki
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: BF - Biotechnical Faculty
• Publisher: [K. Kunčič]
• Year: 2025
• PID: 20.500.12556/RUL-168836
• UDC: 595.2/.7(043.3)
• COBISS.SI-ID: 234638851
• Publication date in RUL: 27.04.2025

Secondary language

• Language: English
• Title: Formation and remodelling of cell junctions in ectodermal and endodermal epithelia of arthropods during development

Abstract

Cell junctions are dynamic complexes that are crucial for epithelial organization and selective permeability. In arthropods, mechanical stability is primarily provided by adherens junctions, whereas septate junctions (SJs) provide a selectively permeable barrier for paracellular transport. We investigated the ultrastructural characteristics of subapical adherens junctions and SJs in the epidermis, hindgut and digestive glands of the arthropod Porcellio scaber (Crustacea: Isopoda). We characterized the remodeling of the ultrastructural structure of the junctions during molting and the differentiation and remodeling of the junctions during embryonic and postembryonic development. Using microcomputed tomography, we have demonstrated the morphogenesis of the organs of the digestive system in the context of the whole organism and, through a complementary analysis of the histological organization of the epithelia and a morphometric analysis of the cells and intercellular junctions at the ultrastructural level, we have characterized the structural changes during development at all the above-mentioned levels of biological organization. We have shown that the ultrastructure of the subapical adherens junctions is similar in all ectodermal epithelia studied and developmental stages analyzed, whereas the ultrastructure of the SJs varies according to the function of the epithelium. The differentiation of the SJs occurs gradually. The pleated SJs, which are characteristic of ectodermal epithelia, change from shorter to longer arrays of septa and are intensively remodeled and shortened during molting. Smooth SJs in endodermal epithelia are already ultrastructurally differentiated at the mid-embryonic stage and during the development of the organism mainly elongate. The comparison with Drosophila suzukii showed differences in the structure of the smooth SJs. Smooth SJs in the endodermal epithelium of the digestive glands of P. scaber are continuous and straight, whereas in the endodermal epithelium of the midgut of D. suzukii they can be discontinuous, convoluted and more extensive.

• Keywords: adherens junctions, isopod, micro-CT, molting, morphogenesis, Porcellio scaber, septate junctions