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Identifier

000452192

Title

Ανάπτυξη τεχνικών φασματομετρίας μάζας και φασματοσκοπίας πυρηνικού μαγνητικού συντονισμού για τη μελέτη της επίδρασης των Ni(II), As(V), Se(VI) στην ακορεστότητα των λιπιδίων των μικροαλγών Chlamydomonas reinhardtii και Chlorella sorokiniana

Alternative Title

Development of mass spectrometric and nuclear magnetic resonance techniques for investigating the effect of Ni(II), As(V), and Se(VI) on lipid saturation in Chlamydomonas reinhartii and Chlorella sorokiniana

Author

Στεργίου, Ευάγγελος Σ.

Thesis advisor

Περγαντής, Σπυρίδων

Reviewer

Απόστολος, Σπύρος
Λυδάκης-Σημαντήρης, Νικόλαος

Abstract

In this thesis, the effect of the presence of Ni²⁺, As⁵⁺, Se⁶⁺ on the lipids of Chlamydomonas reinhardtii (CC-1690 wild type) and Chlorella sorokiniana cells was investigated using mass spectrometry and NMR spectroscopy. The first measurements were performed on Chlamydomonas reinhardtii cells grown in the presence of Ni²⁺ by the technique of sonic spray ionization desorption mass spectrometry (EASI-MS). This technique allows rapid acquisition of mass spectra under ambient conditions with minimal sample preparation. A decrease of the unsaturation levels of PG (34:X) and SQDG (34:X) was observed with increasing Ni²⁺ concentration. This was followed by measurements using HR-MAS (High Resolution Magic Angle Spinning) technique, obtaining ¹H NMR spectra in lyophilized Control cells (cultivated in the absence of additional metal/metalloid) and in cells grown with Ni²⁺ without any additional sample treatment. With increasing Ni²⁺ concentrations, a relative decrease in peak integration corresponding to double bond protons versus fatty acid α-carbon protons was observed. New quantities of Chlamydomonas reinhardtii were then cultured and microextractions of their lipids were performed. The measurements were continued by obtaining ¹H conventional (liquid state) NMR spectra on the lipid extracts, which provided cleaner spectra and showed the tendency of the cells to acquire a less unsaturated lipid profile with increasing concentrations of Ni²⁺, As⁵⁺, Se⁶⁺. Then, the extracts were subjected to efficient analytical separation by C₁₈ column and polar lipids where detected by multiple reaction monitoring (MS/MS, MRM mode). Then, the lipid reorganization of the cells was observed when Ni²⁺ , As⁵⁺, Se⁶⁺ were added to the nutrient by qualitative and semi-quantitative analysis. Finally, Chlorella sorokiniana cells were cultured, which, although belonging to the microalgae class like Chlamydomonas reinhardtii, showed significantly higher tolerance to high concentrations of As⁵⁺ and Se⁶⁺ . Also, although their lipid profile is more unsaturated than that of Chlamydomonas reinhardtii, according to their NMR spectra the lipid unsaturation levels remained constant when grown in the presence of these 3 elements at the studied concentrations, when the cells where incubated with each element separately.

Language

Greek, English

Subject

NMR spectroscopy

Φασματοσκοπία NMR

Issue date

2022-11-24

Collection

School/Department--School of Sciences and Engineering--Department of Chemistry--Post-graduate theses

Type of Work--Post-graduate theses

Permanent Link

https://elocus.lib.uoc.gr//dlib/5/0/8/metadata-dlib-1668508126-917966-8907.tkl