Razvojni procesi uključeni u gubitak nogu kod zmija

undergraduate thesis

• Title (english): Developmental processes involved in limb loss in snakes
• Author: Gabriela Habuš
• Mentor: Romana Gračan (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2024-09-08, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Zmije (Serpentes) zajedno s gušterima (Lacertilia) čine ljuskaše (Squamata) i najpoznatija su skupina životinja kod kojih je prisutan gubitak udova. Fosili zmija nemaju razvijene prednje udove, dok su im stražnji udovi u potpunosti razvijeni. Kod većine današnjih zmija je prisutan potpun gubitak udova i samo zmije skupine Booidea i Scolecophidia imaju rudimentarne stražnje udove. Uz gubitak udova vezana je elongacija trupa koju su zmije postigle ubrzanjem somitogeneze i produljenjem ekspresije gena Oct4, jednog od regulatora ekspresije Hox gena. Hox geni su visoko konzervirani razvojni geni odgovorni za razvitak pojedinih dijelova tijela. Područja ekspresije Hox gena kod zmija uglavnom nisu promijenjena, ali došlo je do promjena u njihovoj interpretaciji što je rezultiralo promjenom u ekspresiji gena važnih za inicijaciju pupoljaka uda i pridonijelo njihovom gubitku. Također tijekom embrionalnog razvoja udova kod zmija ne dolazi do uspostavljanja dvaju signalnih centara zbog mutacija u pojačivačima odgovornim za njihovo održavanje što je i u konačnici rezultiralo potpunim ili djelomičnim gubitkom udova. Nasuprot tome, zmije su zadržale neke gene za razvoj udova koji su uključeni u razvoj vanjskih dijelova genitalija.

Abstract (english)

Snakes (Serpentes) and lizards (Lacertilia) belong to „scaled reptiles“ (order Squamata) and are the most famous clade of animals in which limb loss occurred. Snake fossils do not have forelimbs while their hindlimbs are well developed. Most recent snakes completely lost their limbs and only clades Booidea and Scolecophidia have rudimentary hindlimbs. The loss of limbs is related to the elongation of the trunk which snakes achieved by accelerating somitogenesis and prolonging the expression of the Oct4 gene, one of the regulators of Hox gene expression. Hox genes are highly conserved regulatory genes responsible for the development of certain parts of the body. Their expression domains are mostly unchanged in snakes, but there are changes in their interpretation resulting in a change in the expression of genes important for limb bud initiation which contributed to limb loss. Also, during embryonic development of limbs in snakes, the establishment of two signaling centers does not occur due to mutations in the enhancers responsible for their maintenance, which ultimately resulted in the complete or partial loss of limbs. In contrast, snakes have preserved some genes that are involved both in development of limbs and external genitalia.

• Keywords: regulacija ekspresije gena; signalni centri uda; ZRS; Hox geni; elongacija trupa
• Keywords (english): gene expression regulation; limb signaling centers; ZRS; Hox genes; trunk
• Language: croatian
• URN:NBN: urn:nbn:hr:217:320579
• 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: 2024-09-16 13:27:00