MORPHOLOGICAL AND PHYSIOLOGICAL ADAPTATIONS TO LIFE IN EXTREME ENVIRONMENTAL CONDITIONS

U ovom završnom radu su predstavljena i sažeta dosadašnja znanja temeljnih prilagodbi organizama na život u ekstremnim ekološkim uvjetima. U antropološkom pogledu, staništa nepogodna za čovjeka, imenovana su ekstremnima. Neka od njih smatrana su previše ekstremnima da bi podržali mikroorganizme. Međutim, organizmi su evoluirali i uspješno žive u svim takvim staništima, a nazivamo ih ekstremofilima. Ovisno o njihovima optimalnim uvjetima rasta nazivaju se termofili, psihrofili, acidofili, halofili, itd. Prilagodbe tih organizama su raznolike, a neke od njih su sinteza enzima sa specifičnim strukturnim značajkama, mehanizmi popravaka DNA, jedinstvene stanične membrane te regulacija veličine tijela. Prikazani su primjeri eksperimenata provedenih na dobrim modelima za istraživanje morfoloških i fizioloških prilagodbi. Dugoživci su mikroskopske životinje jedinstveno prilagođene velikom rasponu ekoloških ekstrema. Pokazano je da mogu preživjeti ekstreme ulaskom u kriptobiozu, ali i u aktivnom stanju. Mediteranska biljka, bijeli bušin, kolonizira ekstremna geotermalna područja. Proučavanje njezinih listova pokazalo je stresom inducirane prilagodbe koje joj omogućavaju preživljavanje. Multidisciplinarna istraživanja ekstremofila omogućuju razumijevanje pojave i razvoja života na jedinom planetu na kojem je do sada poznat te su ključna za traženje života u svemiru.This thesis presents and summarizes current knowledge on fundamental adaptations of organisms to life in extreme ecological conditions. In an anthropocentric view, environments hostile to man were designated as extreme. Some of them have originally been considered too extreme to support microbial life. However, organisms have evolved and live in such environments and they are called extremophiles. Depending on their optimal growth conditions, they are named thermophiles, psychrophiles, acidophiles, halophiles, etc. Adaptations in mentioned organisms are diverse and some of them are synthesis of enzymes with specific structural features, DNA repair mechanisms, unique cell membranes and regulation of body size. In this paper examples of experiments conducted on useful models to explore morphological and physiological adaptations are shown. Tardigrades are microscopic animals uniquely adapted to a range of environmental extremes. It is shown that they can survive extremes entering cryptobiosis but even in their active states they can be extremely tolerant. The Mediterranean shrub colonizes extreme geothermal fields. The analyses of its leaves showed stress-induced adaptations involved in their surviving. Multidisciplinary research on extremophiles allows understanding how life appeared and evolved on the only planet where it is so far known and it is crucial if we are to look for life in space