Morphology and phylogeny of picoeukaryotes and planktonic pennate diatoms in the middle and south Adriatic Sea

doctoral thesis

• Title (croatian): Morfologija i filogenija pikoeukariota i penatnih planktonskih dijatomeja u srednjem i južnom Jadranu
• Author: Maja Mucko
• Mentor: Zrinka Ljubešić (mentor)
• Committee member: Sunčica Bosak (predsjednik povjerenstva)
• Granter: University of Zagreb; Faculty of Science; Zagreb
• Defense date and country: 2018-07-06, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES

Abstract

The smallest protists, generally called picoeukaryotes, and planktonic pennate diatoms have received limited attention in world oceans, although they are numerous and important for primary production, biogeochemical cycles and for carbon injection into the deep ocean. In this thesis, represented through seven scientific publications, cultivated planktonic pennate diatoms and picoeukaryotes were investigated with traditional methods (light and electron microscopy, morphometry) and with molecular analyses, including multi-gene phylogenies, and were identified as genera Entomoneis, Pseudo-nitzschia, Haslea and Picochlorum. Detailed investigations of genus Entomoneis resulted with description of seven new species. General picoeukaryotic diversity was addressed by eDNA amplicon sequencing V4 variable region of nuclear 18S rRNA gene. Obtained results identified 95% of the picoeukaryotic community as hetero- or mixotrophic, mostly belonging to parasitic dinoflagellates and radiolarians, while only 5% of the community was represented with photoautotrophic picoeukaryotes belonging to classes of green algae, haptophytes, stramenopiles and cryptophytes. One cultivated Picochlorum sp. strain was subjected to growth rate experiment and pigment and lipid analyses, resulting in interesting and promising data for future biotechnological studies.

Abstract (croatian)

Najmanji protisti, poznati kao pikoeukarioti i penatne planktonske diatomeje često su zanemareni u istraživanjima svjetskih oceana, iako predstavljaju brojnu i važnu komponentu za primarne proizvodnje, biogeokemijskih ciklusa i značajni su za protok ugljika u duboki ocean. U sklopu ove disertacije kroz sedam znanstvenih publikacija navedene skupine organizama istraživane su tradicionalnim metodama (svjetlosna i elektronska mikroskopija, morfometrija) i molekularnim analizama koje uključuju filogenetske anlize sa više različitih genskih markera te su identificirane kao rodovi Entomoneis, Pseudo-nitzschia, Haslea i Picochlorum. Detaljna analiza roda Entomoneis rezultirala je opisom sedam novih vrsta za znanost. Bioraznolikost ukupne pikoeukariotske zajednice u južnom Jadranu odredila se sekvenciranjem amplikona okolišne DNA i to prema varijabilnoj V4 regiji nuklearnog 18S rRNA gena. Dobiveni rezultati identificirali su 95% pikoeukariotske zajednice kao hetero- ili miksotrofne organizme, većim dijelom pripadajući parazitskim dinoflagelatima i radiolarijama, dok je samo 5% zajednice zastupljeno fotoautotrofnim pikoeukariotima koji pripadaju razredima zelenih algi, haptofita, stramenopila i kriptofita. Jedan kultivirani soj alge Picochlorum sp. istražen je kroz eksperiment određivanja brzine rasta te analizama pigmenta i lipida, što je rezultiralo zanimljivim i obećavajućim rezultatima koji mogu poslužiti kao okosnica za buduće biotehnološke studije.

• Keywords: picoeukaryotes; planktonic pennate diatoms; morphology; phylogeny
• Keywords (croatian): pikoeukarioti; penatne planktonske dijatomeje; morfologija; filogenija
• Language: english
• URN:NBN: urn:nbn:hr:217:928047
• Study programme: Title: Biology; Study programme type: university; Study level: postgraduate
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-09-04 11:32:21