Funkcionalna građa i toksini nematocista meduzoidnih žarnjaka

undergraduate thesis

• Title (english): Functional stucture and toxins of nematocysts in jellyfish cnidarians
• Author: Petra Mlacović
• Mentor: Biserka Primc (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2016, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Koljeno Cnidaria dijeli se na četiri razreda od kojih koralji nemaju, a režnjaci, kubomeduze i obrubnjaci imaju oblik meduze. Glavno obilježje po kojem se žarnjaci razlikuju od ostalih životinja je postojanje knidocita, specijaliziranih stanica koje imaju ulogu hvatanja plijena, obrane i prianjanja na površinu. Razlikujemo tri tipa knidocita: spirociste, ptihociste i nematociste. Spirociste i ptihociste nalazimo kod koralja, dok kod meduza nalazimo samo nematociste. Postoji više od 30 različitih oblika nematocista koje u sebi nose toksine različitih sastava. Nematociste se sastoje od čahure i cjevčice koja se potaknuta kemijskim ili mehaničkim podražajima izbacuje i prilikom izbacivanja probija epidermu žrtve i u nju ispušta otrov. Do izbacivanja cjevčice dolazi zbog porasta tlaka u stanici, a sam proces izbacivanja jedan je od najbržih bio-mehaničkih procesa u prirodi. Nematociste se dijele na astomoknide koje imaju zatvoren vrh cjevčice i stomoknide koje imaju otvor na vrhu cjevčice. Stomoknide se dijele na temelju razlika u bodljama na cjevčici, izgledu cjevčice i duljini izbačenog drška i cjevčice u odnosu na duljinu čahure. Do danas je definirano 156 različitih toksina uz nematocista. Kao toksine najčešće nalazimo enzime, neurotoksine, toksine koji formiraju pore na membranama stanice žrtve i neproteinske bioaktivne komponente. Od svih danas poznatih meduza najpoznatije su one najotrovnije kao na primjer morska osa (Chironex fleckeri) i modri loptaš (Physalia physalis) te one najrasprostranjenije kao morska mjesečina (Pelagia noctiluca) i ušati klobuk (Aurelia aurita).

Abstract (english)

Phylum Cnidaria is divided in four classes of which Anthozoa do not, but Scyphozoa, Cubozoa and Hydrozoa do have the shape of jellyfish. The main characteristic on which Cnidaria diverse from other animals is the existence of cnidocyts, specialised cells which have a role in capturing prey, defence and adhesion to the surface. There are three types of cnidocysts: spirocysts, ptychocysts and nematocysts. Spirocysts and ptychocysts are found in Anthozoa, while nematocysts are found only in jellyfish. There are more than 30 shapes of nematocysts which contain differently structured toxins. Nematocysts consist of shaft and tubule which when chemically or mechanically stimulated ejects and penetrates epidermis of the victim and releases its poison. The tubule is ejected because the pressure in the cell rises, that process of ejection is one of the fastest bio-mechanical processes in nature. There are two types of nematocysts: astomocnidae whose tubule is closed at the tip and stomocnidae whose tubule is opened at the tip. Stomocnidae are divided based on the differences in tubule thorns, morphology of the tubule and the length of the everted shaft and tubule compared to the length of closed shaft. Until today 156 different toxins from nemtocysts have been defined. Most common toxins are enzymes, neurotoxins, pore forming toxins and non-protein bioactive components. From all known jellyfish, the most famous ones are the most poisonous such as Chironex fleckeri and Physalia physalis and those that are spreaded all around the world such as Aurelia aurita and Pelagia noctiluca.

• Keywords: žarnjaci; nematociste
• Keywords (english): cnidarians; nematocysts
• Language: croatian
• URN:NBN: urn:nbn:hr:217:801145
• Study programme: Title: Environmental Sciences; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) struke znanosti o okolišu (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) struke znanosti o okolišu)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-01-03 10:44:40