Rhizostoma pulmo - Univerza v Novi Gorici

POVZETEK
Meduze velikega klobučnjaka (Rhizostoma pulmo) se pojavljajo skozi vse leto, a v
zelo majhnem številu. V zadnjih letih je bilo v Tržaškem zalivu zabeleženih več
množičnih pojavljanj velikega klobučnjaka v zimskem obdobju. Poleg te vrste so se
množično pojavljale še druge klobučnjaške meduze kot so uhati klobučnjak (Aurelia
aurita), v poletnih mesecih pa mesečinka (Pelagia noctiluca). Poznamo več
dejavnikov, ki naj bi vplivali na njihovo množično pojavljanje, med katerimi so
nekateri posledica človekove dejavnosti, nekatera nihanja v številčnosti pa so
naravna nihanja.
V diplomskem delu smo želeli raziskati filogenetsko povezanost meduz velikega
klobučnjaka iz severnega Jadrana in Črnega morja. Filogenetsko povezanost smo
raziskovali z analizo nukleotidnih zaporedij v genu za citokrom c oksidazo (COI), ki
se nahaja na mitohondrijski DNA (mtDNA). Del tega gena (podenota I) smo
pomnožili s PCR z univerzalnimi začetnimi oligonukleotidi za nevretenčarje. Iz
pomnoženih fragmentov COI smo pridobili nukleotidna zaporedja. Na osnovi analize
le teh smo analizirali filogenetske odnose med vzorčenimi osebki. S filogenetsko
primerjavo nukleotidnih zaporedij COI iz velikega klobučnjaka v vzorcih iz Črnega
morja in severnega Jadrana smo ugotovili, da je v nukleotidnih zaporedjih
80 odstotkov ohranjenih mest. Veliki klobučnjaki iz Črnega morja in severnega
Jadrana tvorijo dve ločeni filogenetski skupini, kar je razvidno iz filogenetskega
drevesa. COI se je izkazal kot primeren genetski marker za razlikovanje med vzorci
iz Črnega morja in severnega Jadrana. To je prva tovrstna študija, saj zaenkrat še ni
nobenih javno dostopnih nukleotidnih zaporedij COI iz velikega klobučnjaka.
Ključne besede: Scyphozoa, Rhizostoma pulmo, mitohondrijska DNA (mtDNA),
citokrom c oksidaza, filogeografija, antropogeni vplivi, množično pojavljanje
SUMMARY
Medusae of Rhizostoma pulmo are occurring throughout all year in small number. In
recent years several mass appearances have been recorded in Trieste Bay during
winter time. Except for this species other scyphozoan species have been appearing
massively in Gulf of Trieste as well, such as moon jelly (Aurelia aurita), and also
mauve stinger (Pelagia noctiluca) during summer. There are several factors
affecting their mass occurrence due to anthropogenic activities and also natural
origin.
The aim of my diploma dissertation was to examine phylogenetic connections
between medusae of Rhizostoma pulmo from the northern Adriatic Sea and of the
Black Sea. The research of phylogenetic connection was carried out with an
analysis of nucleotide sequences of the gene encoded cytochrome c oxidase
subunit (COI) found in mitochondrial DNA (mtDNA). A part of this gene (subunit) has
been amplified by PCR with universal oligonucleotide primers for invertebrates and
sequenced with the same primer pair. On the basis of the nucleotide sequences
analysis were performed phylogenetic relationships between sampled individuals
were performed and estimation of gene flow and phylogenetic relationship were
revealed. On the basis of phylogenetic comparison of COI nucleotide sequences of
Rhizostoma pulmo in the samples from the Black Sea and the northern Adriatic Sea
we determined that nucleotide sequences contain 80 % of conserved sites.
Rhizostoma pulmo from the Black Sea and the Northern Adriatic Sea form two
separated phylogenetic groups, as revealed by phylogenetic tree. COI proved to be
a suitable genetic marker to distinguish between samples from the Black Sea and
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