Metalotioneini kao biomarkeri izloženosti metalima u školjkaša

undergraduate thesis

• Title (english): Bivalve metallothioneins as biomarkers of metal exposure
• Author: Zuzana Redžović
• Mentor: Jasna Lajtner (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2015, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Organizmi koji žive u morskim, estuarijskim i slatkovodnim ekosustavima često su izloženi antropogenom utjecaju. Među onečišćujućim tvarima, metali imaju posebnu važnost jer nisu biorazgradivi. Školjkaši se hrane filtracijom vode i pri tome akumuliraju visoke razine teških metala pa se koriste kao bioindikatorski organizmi onečišćenja metalima. Izloženost toksičnim metalima za njih predstavlja stres jer se oni vežu za esencijalne biomolekule. Stoga školjkaši razvijaju mnoge detoksikacijske mehanizme kako bi uklonili metale iz blizine bitnih molekula. Jedan od načina je taj da se metali vežu na metalotioneine (MT-e). MT-i su citosolni proteini male molekulske mase, koji su odgovorni za održavanje homeostaze esencijalnih (Zn, Cu) i detoksikaciju toksičnih metala (Cd, Hg, Ag). Ovi metali induciraju sintezu MT-a i vežu se na njega. Pobudna sinteza MT-a predstavlja biomarker izloženosti metalima. MT-i se kao biomarkeri koriste u biomonitoringu jer rano upozoravaju na onečišćenje okoliša i na štetne učinke zagađivača. Unos metala u školjkaše se odvija putem škrga, probavne žlijezde i površine plašta te se stoga u njima mjeri razina MT-a. Međutim, brojni biotički i abiotički parametri mogu utjecati na povećanu sintezu MT-a. Stoga je potrebno razlikovati utjecaj okolišnih čimbenika od antropogenog utjecaja. Također, odgovor MT-a na izloženost metalima ovisi o organizmu, tkivu koje se ispituje i o izoformi MT-a koja se proučava. Primjena MT-a kao biomarkera izloženosti metalima kod školjkaša korisna je u mnogim ekotoksikološkim istraživanjima te je od velikog značaja za procjenu razine zagađenosti vodenih ekosustava.

Abstract (english)

Organisms that live in marine, estuary and fresh ecosystems are often exposed to anthropogenic influence. Among the pollutants, metals are of major concern because they are not biodegradable. Bivalves are filter-feeding organisms and accumulate high levels of heavy metals. Therefore, they are widely used as bioindicators of metal contamination. Exposure to toxic metals is stressful because metals can bind to essential biomolecules. Therefore, bivalves develop detoxification mechanisms to remove metals from the vicinity of important molecules. This may be achieved by binding metals to metallothioneins (MT-s). MT-s are cytosolic low-molecular weight proteins which are responsible for maintaining homeostasis of essential (Zn, Cu) and detoxification of non-toxic metals (Cd, Hg, Ag). These metals are inducers of MT synthesis and bind on MT. Induction of MT is considered as biomarker of metal exposure. MT-s are used as biomarkers in biomonitoring because they are early-warning indicators of pollution and signal harmful effects of contaminants. The uptake of metals may take place via gills, digestive gland or via the surface of the mantle so level of MT is measured in them. However, many biotic and abiotic factors can influence higher synthesis of MT. Therefore, it is necessary to distinguish between the impact of environment factors and anthropogenic contaminants. Also, MT response to metals depends on the organism, the tissue examined and the MT isoform studied. Applying MT-s in bivalves as biomarkers of metal exposure is useful in many ecotoxicological studies and is of great importance to assess level of contamination in aquatic environment.

• Keywords: školjkaši; metalotioneini
• Keywords (english): bivalves; metallothioneins
• Language: croatian
• URN:NBN: urn:nbn:hr:217:568221
• Study programme: Title: Ecology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-12-18 09:30:08