{"id":6417,"date":"2026-10-19T09:48:53","date_gmt":"2026-10-19T09:48:53","guid":{"rendered":"https:\/\/phd.hi.is\/doktorsvorn\/doktorsvorn-i-matvaelafraedi-monica-daugbjerg-christensen\/"},"modified":"2026-10-19T09:48:53","modified_gmt":"2026-10-19T09:48:53","slug":"doktorsvorn-i-matvaelafraedi-monica-daugbjerg-christensen","status":"publish","type":"phd_defence","link":"https:\/\/phd.hi.is\/en\/doktorsvorn\/doktorsvorn-i-matvaelafraedi-monica-daugbjerg-christensen\/","title":{"rendered":"Doktorsv\u00f6rn \u00ed matv\u00e6lafr\u00e6\u00f0i &#8211; Monica Daugbjerg Christensen"},"content":{"rendered":"<div class=\"field-items\">\n<div class=\"field-item even\" property=\"content:encoded\">\n<p>Fimmtudaginn 2. okt\u00f3ber 2025 ver Monica Daugbjerg Christensen\u00a0 doktorsritger\u00f0 s\u00edna \u00ed matv\u00e6lafr\u00e6\u00f0i vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands. Ritger\u00f0in ber heiti\u00f0: Einangrun og ni\u00f0urbrot sj\u00e1varfj\u00f6lsykra og mat \u00e1 \u00f3n\u00e6mism\u00f3tandi \u00e1hrifum \u00feeirra. Refining marine polysaccharides and their immunomodulatory effects.<\/p>\n<p>Andm\u00e6lendur eru dr. Kari Tvete Inngjerdingen, d\u00f3sent vi\u00f0 H\u00e1sk\u00f3lann \u00ed \u00d3sl\u00f3, og dr. Finn Aachmann, pr\u00f3fessor vi\u00f0 Norwegian University of Science and Technology.\u00a0<\/p>\n<p>Umsj\u00f3narkennarar voru Hildur Inga Sveinsd\u00f3ttir, lektor og Gu\u00f0j\u00f3n \u00deorkelsson, pr\u00f3fessor. Lei\u00f0beinendur voru Gu\u00f0mundur \u00d3li Hreggvi\u00f0sson, pr\u00f3fessor og stefnum\u00f3tandi s\u00e9rfr\u00e6\u00f0ingur, og J\u00f3na Freysd\u00f3ttir, pr\u00f3fessor. Auk \u00feeirra s\u00e1tu \u00ed doktorsnefnd \u00d3lafur H. Fri\u00f0j\u00f3nsson, fagstj\u00f3ri og Eva Nordberg Karlsson, pr\u00f3fessor.<\/p>\n<p>Ingibj\u00f6rg Gunnarsd\u00f3ttir, pr\u00f3fessor og varadeildarforseti Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideildar, stj\u00f3rnar ath\u00f6fninni sem fer fram \u00ed H\u00e1t\u00ed\u00f0asal H\u00e1sk\u00f3la \u00cdslands og hefst kl. 13.30.<\/p>\n<p><strong>\u00c1grip<\/strong><\/p>\n<p>Br\u00fan\u00fe\u00f6rungar innihalda miki\u00f0 magn af fj\u00f6lbreytilegum fj\u00f6lsykrum sem hafa margv\u00edslega l\u00edfvirkni. \u00cd \u00feessu doktorsverkefni var kanna\u00f0 \u00e1 fj\u00f3ra vegu hvernig nota megi ens\u00edm til umbreyta sj\u00e1varfj\u00f6lsykrum og \u00e1hrifum \u00feeirra \u00e1 \u00f3n\u00e6miskerfi\u00f0. 1) N\u00fdr s\u00falfatasi, SulA1, \u00far sj\u00e1varbakter\u00edunni Arthrobacter, var framleiddur me\u00f0 erf\u00f0at\u00e6knilegum a\u00f0fer\u00f0um og rannsaka\u00f0ur \u00edtarlega.\u00a0 SulA1 s\u00falfatasinn gat fjarl\u00e6gt s\u00falfath\u00f3p af N-Acetyl-D-galactosamine-4-sulfate sem endurspeglar eiginleika hans vi\u00f0 a\u00f0 fjarl\u00e6gja s\u00falfath\u00f3pa og breyta \u00feannig l\u00edfvirkni fj\u00f6lsykra. 2) Laminarin sameindir \u00far \u00feremur ger\u00f0um br\u00fan\u00fe\u00f6runga (Laminaria digitata, L. hyperborea, and Saccharina latissima) voru einangra\u00f0ar og klipptar ni\u00f0ur \u00ed sm\u00e1sykrur. Bygging sm\u00e1sykranna var greind og kom \u00ed lj\u00f3s a\u00f0 st\u00e6r\u00f0 og greining \u00feeirra haf\u00f0i \u00e1hrif \u00e1 bo\u00f0efnaseytun angafrumna og getu \u00feeirra til a\u00f0 r\u00e6sa og s\u00e9rh\u00e6fa T-frumur. \u00deessar ni\u00f0urst\u00f6\u00f0ur benda til \u00feess a\u00f0 hugsanlega s\u00e9 unnt a\u00f0 nota laminarin sameindir og aflei\u00f0ur \u00feeirra \u00ed me\u00f0fer\u00f0 \u00e1 sj\u00fakd\u00f3mum tengdum \u00f3n\u00e6miskerfinu. 3) F\u00fak\u00f3\u00eddan \u00far S. latissima var klippt ni\u00f0ur \u00ed f\u00e1sykrur af mismunandi st\u00e6r\u00f0. Stuttar f\u00e1sykrur h\u00f6f\u00f0u b\u00f3lguhamlandi \u00e1hrif me\u00f0 \u00fev\u00ed a\u00f0 minnka seytun angafrumna \u00e1 b\u00f3lgubo\u00f0efnum og draga \u00feannig \u00far Th1 \u00f3n\u00e6missvari. \u00de\u00e6r g\u00e6tu \u00fev\u00ed hugsanlega n\u00fdst vi\u00f0 me\u00f0fer\u00f0 \u00e1 b\u00f3lgusj\u00fakd\u00f3mum. 4) Tv\u00e6r f\u00e1sykrur \u00far alg\u00ednati juku seytun angafrumna \u00e1 b\u00f3lgubo\u00f0efnum og \u00fdttu undir Th1 sv\u00f6run T frumna \u00ed samr\u00e6kt. \u00deetta bendir til \u00feess a\u00f0 \u00feessar f\u00e1sykrur geti n\u00fdst vi\u00f0 eflingu \u00f3n\u00e6missvars, t.d. \u00ed me\u00f0fer\u00f0 vi\u00f0 krabbameinum e\u00f0a sem \u00f3n\u00e6misgl\u00e6\u00f0ar. Til samans s\u00fdna ni\u00f0urst\u00f6\u00f0ur \u00feessa verkefnis a\u00f0 ni\u00f0urbrot sj\u00e1varfj\u00f6lsykra me\u00f0 ens\u00edmum geti haft \u00e1hrif \u00e1 \u00f3n\u00e6misvirkni ni\u00f0urbrotsefnanna sem eykur l\u00edkur \u00e1 notkun \u00feeirra \u00ed \u00fer\u00f3un me\u00f0fer\u00f0a \u00e1 sj\u00fakd\u00f3mum \u00ed \u00f3n\u00e6miskerfinu. Auk \u00feess g\u00e6ti \u00feetta leitt til umhverfisv\u00e6nnar vinnslu \u00e1 fj\u00f6lsykrum \u00far br\u00fan\u00fe\u00f6rungum me\u00f0 ens\u00edmum sem getur auki\u00f0 ver\u00f0m\u00e6ti \u00feeirra og notkunargildi \u00ed lyfja- og f\u00e6\u00f0ub\u00f3tari\u00f0na\u00f0i.<\/p>\n<p><strong>Abstract<\/strong><\/p>\n<p>Brown seaweed is a rich source of structurally diverse polysaccharides with promising bioactive properties. This study investigated in four ways how enzymatic refining can modify marine polysaccharides and influence their immunomodulatory effects. 1) A novel sulfatase, SulA1, cloned from a marine Arthrobacter strain, was characterized, and shown to selectively act on the chondroitin sulfate monosaccharide N-Acetyl-D-galactosamine-4-sulfate. This introduced the possibilities for the use of SulA1 in targeted desulfation strategies to alter bioactivity of targeted molecules. 2) Laminarin from three brown seaweed species (Laminaria digitata, L. hyperborea, and Saccharina latissima) was extracted and enzymatically modified. The laminarin derivatives were structurally analysed and found to distinctly regulate dendritic cell activity depending on their molecular size and branching pattern. These data suggest that different laminarin derivatives may have different therapeutic applications within the immune system. 3) Fucoidan from S. latissima was enzymatically refined into defined molecular weight fractions. The low molecular weight fucoidan fraction significantly suppressed the secretion of the pro-inflammatory cytokine by dendritic cells, indicating potential therapeutic applications against inflammatory diseases. 4) Two enzymatically generated alginate oligosaccharide fractions, enhanced cytokines secretion by dendritic cells and promoted Th1 responses in co-cultures with T cells. These findings highlight distinct immunomodulatory properties of alginate oligosaccharides with potential therapeutic relevance in inducing inflammatory responses, e.g. as adjuvants or in cancer treatment. Collectively, these results demonstrate that targeted enzymatic modifications can reshape the immunomodulatory activity of marine-derived polysaccharides, positioning them as promising candidates for therapeutic development. At the same time, this strategy enhances the efficient use of seaweed biomass and supports the creation of sustainable, high-value products with potential applications in pharmaceuticals and nutraceuticals.<\/p>\n<p><strong>Um doktorsefni<\/strong><\/p>\n<p>Monica Daugbjerg Christensen er f\u00e6dd \u00e1ri\u00f0 1988 \u00ed Danm\u00f6rku. H\u00fan \u00fatskrifa\u00f0ist af st\u00e6r\u00f0fr\u00e6\u00f0ibraut Menntask\u00f3lans \u00ed Aller\u00f8d \u00e1ri\u00f0 2007. Monica lauk B.Sc. pr\u00f3fi \u00ed l\u00edf- og l\u00edft\u00e6knifr\u00e6\u00f0i \u00e1ri\u00f0 2011 fr\u00e1 H\u00e1sk\u00f3lanum \u00ed Kaupmannah\u00f6fn og M.Sc. gr\u00e1\u00f0u, einnig \u00ed l\u00edf- og l\u00edft\u00e6knifr\u00e6\u00f0i, fr\u00e1 sama sk\u00f3la \u00e1ri\u00f0 2014. \u00c1ri\u00f0 2017 h\u00f3f h\u00fan doktorsn\u00e1m vi\u00f0 Matv\u00e6la- og n\u00e6ringarfr\u00e6\u00f0ideild H\u00e1sk\u00f3la \u00cdslands og vann ranns\u00f3knir s\u00ednar vi\u00f0 l\u00edft\u00e6knideild Mat\u00eds ohf. og \u00f3n\u00e6misfr\u00e6\u00f0ideild Landsp\u00edtala. \u00c1 n\u00e1mst\u00edma s\u00ednum t\u00f3k h\u00fan \u00fe\u00e1tt \u00ed kennslu og lei\u00f0beiningu nemenda \u00e1 \u00f3n\u00e6misfr\u00e6\u00f0ideildinni. Foreldrar Monicu eru Jens Hesselbjerg Christensen og Conni Daugbjerg Christensen. Eiginma\u00f0ur Monicu er Henrik Holst Jensen og saman eiga \u00feau tvo syni, Patrik N\u00f3a, fimm \u00e1ra og Jakob M\u00e1na, eins \u00e1rs.<\/p>\n<p>\u00a0<\/p>\n<\/div><\/div>","protected":false},"featured_media":5804,"template":"","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"_phd_date_start":"2025-10-02T13:30:00+00:00","_phd_date_end":"2025-10-02T16:30:00+00:00","_phd_location":"A\u00f0albygging H\u00e1t\u00ed\u00f0asalur","_phd_admission":"A\u00f0gangur \u00f3keypis","_phd_thesis_title":"Einangrun og ni\u00f0urbrot sj\u00e1varfj\u00f6lsykra og mat \u00e1 \u00f3n\u00e6mism\u00f3tandi \u00e1hrifum \u00feeirra. 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