Uvid u molekularne mehanizme tijekom oplodnje u sisavaca

undergraduate thesis

• Title (english): Insight into molecular events during mammalian fertilisation
• Author: Ena Rajić
• Mentor: Romana Gračan (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2024-07-24, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Tijekom oplodnje, spajanjem spermija i jajne stanice, nastaje diploidna zigota iz koje kreće razvitak cijeloga organizma. Uspješnost oplodnje osigurava kapacitacija tj. sazrijevanje spermija unutar ženskog spolnog sustava. Zahvaljujući ulasku HCO3- i Ca2+ te izlasku H+ iona iz glave spermija te djelovanju progesterona dolazi do povišenja unutarstaničnog pH i hiperaktivacije spermija koja omogućuje prodor spermija do jajne stanice. Navođenju spermija potpomažu estrogeni koji uzrokuju pasivno kretanje spermija te kemotaksija, termotaksija i reotaksija – procesi koji su na molekularnoj razini povezani s povišenjem unutarstanične koncentracije Ca2+ spermija. Nakon približavanja gameta u jajovodu, dolazi do interakcije između SED-1 receptora na glavi spermija i zone pellucide što omogućuje vezanje ZP3 glikoproteina na β1,4-galactoziltransferazu-I spermija. Ova interakcija uzrokuje akrosomsku reakciju kojom se razgrađuje zona pellucida i omogućuje približavanje membrana oocite i spermija. U adheziji staničnih membrana važna je interakcija IZUMO1 (na glavi spermija) i Juno proteina (na oociti), dok proteini koji sudjeluju u fuziji staničnih membrana još uvijek nisu poznati. Također, tijekom oplodnje, povišenje unutarstanične koncentracije Ca2+ uzrokuje kortikalnu reakciju. Njome dolazi do stvaranje fertilizacijske membrane te oslobađanja enzima ovastacina čijim djelovanjem dolazi do promjene strukture ZP2 glikoproteina, otvrdnuća zone pellucide i sprječavanja polispermije.

Abstract (english)

During fertilisation, the fusion of the sperm and ovum forms a diploid zygote, marking the beginning of the organism's development. The success of fertilisation is ensured by capacitation, the maturation of sperm within the female reproductive system. The entry of HCO3- and Ca2+ and the exit of H+ ions from the head of the sperm, as well as the effects of progesterone, all cause an increase in the intracellular pH and hyperactivation of the sperm, which facilitates its penetration toward the ovum. Sperm guidance within the female reproductive system is aided by estrogens, which promote passive movement, as well as chemotaxis, thermotaxis and rheotaxis - processes that are all dependent on the increase in sperm intracellular Ca2+ concentration. When the gametes meet in the oviduct, the interaction between the SED-1 receptor on the sperm head and the zona pellucida enables the binding of the ZP3 glycoprotein to β1,4-galactosyltransferase-I on the sperm. This interaction triggers the acrosomal reaction, which dissolves zona pellucida. The adhesion of the cell membranes depends on the interaction of IZUMO1 (on the sperm head) and Juno protein (on the oocyte), while the proteins involved in their fusion are still unknown. The increase in intracellular Ca2+ concentration during fertilisation causes a cortical reaction, leading to the formation of a fertilisation membrane and the release of the enzyme ovastacin. Ovastacin alters the structure of the ZP2 glycoprotein, hardening the zona pellucida and preventing polyspermy.

• Keywords: kapacitacija; akrosomska reakcija; kemotaksija; termotaksija; reotaksija; kortikalna reakcija
• Keywords (english): capacitation; acrosomal reaction; chemotaxis; thermotaxis; rheotaxis; cortical reaction
• Language: croatian
• URN:NBN: urn:nbn:hr:217:558043
• Study programme: Title: Molecular biology-University undergraduate programme; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-07-05 10:48:01