Toksični učinki izbranih kovin na razmnoževanje alge Chlamydomonas reinhardtii

Lesjak, Neža (author), Eleršek, Tina (mentor)

V okviru diplomske naloge smo preučevali toksične učinke izbranih kovin na razmnoževanje alge Chlammydomonas reinhardtii s pomočjo parametrov, kot so gostota celic, inhibicija razmnoževanja, efektivna koncentracija in fluorescenca. Zastavljeni cilji diplomskega dela so raziskati in primerjati učinek kovin selena(VI) in arzena(V) pri EC20 s pomočjo razlike mediane fluorescence in določiti inhibicijio razmnoževanja alg WT. V prvem sklopu raziskovanja smo celice C. reinhardtii obdelovali z različnimi koncentracijami arzena(V) in selena(VI) v ločenih poskusih. Delo smo opravljali v primerno zaščitenem okolju. Na podlagi smernic OECD 201 smo izvedli test rastne inhibicije na algah, ki je trajal 72 ur. Kulturo alg smo najprej morfološko pregledali s pomočjo mikroskopa in najboljšo kulturo iz knjižnice prenesli v erlenmajerico s TAP medijem ter jo dali na stresalnik v rastno komoro, da so se celice namnožile do pozne eksponentne faze. Vzorce izpostavljene kovinam in kontrolne vzorce smo na vsakih 24 ur prenašali na mikrotitrsko ploščo in s pomočjo pretočnega citometra izmerili fluorescenco in gostoto celic, ki smo jih uporabili za analizo podatkov v drugem sklopu diplomskega dela. Glede na naše rezultate izbrani kovini lahko škodujeta algam v vodnih okoljih. Arzen(V) je strupen za C. reinhardtii že od 7mg/L naprej, pri 48 mg/L pa skoraj popolnoma inhibira rast (95% inhibicija). Selen(VI) pa je strupen za izbrano algo že od 0,2 mg/L naprej, pri 2 mg/L pa povzroča 99% inhibicijo razmnoževanja. Eksperimentalno dobljena EC20 za arzen(V) je 15,4 mg/L, medtem ko je E20 za selen(VI) 0,4 mg/L, kar kaže na večjo toksičnost selena. Pri obdelovanju mešanice mutant s kovinami je bila na podlagi gostote celic in inhibicije ugotovljena manjša občutljivost v primerjavi z divjim tipom C. reinhardtii. Zbrani podatki kažejo na toksičnost izbranih elementov in posledično zbujajočo skrb za okolje.

• Language: Slovenian
• Keywords: toksični vpliv, inhibicija razmnoževanja, gostota celic, fluorescenca klorofila, EC20, EC50, arzen(V), selen(VI), mikroalga Chlammydomonas reinhardtii
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: BF - Biotechnical Faculty
• Year: 2023
• PID: 20.500.12556/RUL-148589
• COBISS.SI-ID: 162559747
• Publication date in RUL: 27.08.2023

LESJAK, Neža, 2023, Toksični učinki izbranih kovin na razmnoževanje alge Chlamydomonas reinhardtii [online]. Bachelor’s thesis. [Accessed 5 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=148589

Secondary language

• Language: English
• Title: Toxic effects of selected metals on reproduction of the algae Chlamydomonas reinhardtii

Abstract

The aim of the B. Sc Thesis was to investigate toxic effects of selected metals on the reproduction of algae Chlamydomonas reinhardtii using parameter such as cell density, inhibition of reproduction, effective concentration and fluorescence. The objectives of the thesis are to investigate and compare the effect of selenium(VI) and arsenic(V) metals at EC20 and to determine the inhibition of algal reproduction by WT using the difference in median fluorescence. In the first set of studies, C. reinhardtii cells were treated with different concentrations of arsenic(V) and selenium(VI) in separate experiments. The work was carried out in a suitably protected environment. A growth inhibition test was carried out for 72 hours based on the OECD 201 guidelines for algae or cyanobacteria. The algal culture from the library was first examined morphologically using a microscope and the best culture was transferred into a flask with TAP medium and placed on a shaker in a growth chamber to multiply the cells to the late exponential phase. Subsequently, treated samples and controls were transferred every 24 hours to a microtiter plate and using a flow cytometer recorded fluorescence and cell density data, which were used for data analysis in the second part of the thesis. According to our results, the selected metals may be harmful to algae in aquatic environments. Arsenic(V) is toxic to C. reinhardtii from 7 mg/L onwards and almost completely inhibits growth at 48 mg/L (95% inhibition). Selenium(VI) is toxic to selected algae from 0.2 mg/L onwards and causes 99% inhibition of reproduction at 2 mg/L. The experimentally obtained EC20 for arsenic(V) is 15.4 mg/L, while the E20 for selenium(VI) is 0.4 mg/L, indicating a higher toxicity of selenium. The treatment of the mutant mixture showed a lower sensitivity compared to wild type C. reinhardtii based on cell density and inhibition. The obtained data indicate toxicity of the selected elements represent an environmental concern.

• Keywords: toxicity, inhibition of reproduction, cell density, chlorophyll fluorescence, EC20, EC50, arsenic(V), Se(VI), microalga Chlamydomonas reinhardtii