Antje Hofgaard

• Blanc-Mathieu, Romain; Dahle, Håkon; Hofgaard, Antje; Brandt, David; Ban, Hiroki & Kalinowski, Jörn [Show all 8 contributors for this article] (2021). A persistent giant algal virus, with a unique morphology, encodes an unprecedented number of genes involved in energy metabolism. Journal of Virology. ISSN 0022-538X. 95(8), p. 1–58. doi: 10.1128/JVI.02446-20.
• Ikram, Samman; Heikal, Adam; Finke, Sarah; Hofgaard, Antje; Rehman, Yasir & Sabri, Anjum Nasim [Show all 7 contributors for this article] (2019). Bacillus cereus biofilm formation on central venous catheters of hospitalised cardiac patients. Biofouling (Print). ISSN 0892-7014. 35(2), p. 204–216. doi: 10.1080/08927014.2019.1586889. Full text in Research Archive Show summary

  Formation of bacterial biofilms is a risk with many in situ medical devices. Biofilm-forming Bacillus species are associated with potentially life-threatening catheter-related blood stream infections in immunocompromised patients. Here, bacteria were isolated from biofilm-like structures within the lumen of central venous catheters (CVCs) from two patients admitted to cardiac hospital wards. Isolates belonged to the Bacillus cereus group, exhibited strong biofilm formation propensity, and mapped phylogenetically close to the B. cereus emetic cluster. Together, whole genome sequencing and quantitative PCR confirmed that the isolates constituted the same strain and possessed a range of genes important for and up-regulated during biofilm formation. Antimicrobial susceptibility testing demonstrated resistance to trimethoprim-sulphamethoxazole, clindamycin, penicillin and ampicillin. Inspection of the genome revealed several chromosomal beta-lactamase genes and a sulphonamide resistant variant of folP. This study clearly shows that B. cereus persisting in hospital ward environments may constitute a risk factor from repeated contamination of CVCs.

• Engesmo, Anette; Eikrem, Wenche; Seoane, Sergio; Smith, Kirsty; Edvardsen, Bente & Hofgaard, Antje [Show all 7 contributors for this article] (2016). New insights into the morphology and phylogeny of Heterosigma akashiwo (Raphidophyceae), with the description of Heterosigma minor sp. nov. Phycologia. ISSN 0031-8884. 55(3), p. 279–294. doi: 10.2216/15-115.1.
• Rowe, Melissah; Griffith, Simon C.; Hofgaard, Antje & Lifjeld, Jan Terje (2015). Subspecific variation in sperm morphology and performance in the Long-tailed Finch (Poephila acuticauda). Avian Research. ISSN 2053-7166. 6:23, p. 1–10. doi: 10.1186/s40657-015-0032-z.
• Hofgaard, Antje; Gillespie, Leah; Morgan, Garry; van der Heide, Peter; Khromykh, Alexander & Mackenzie, Jason (2014). The West Nile virus assembly process evades the conserved antiviral mechanism of the interferon-induced MxA protein. Virology. ISSN 0042-6822. 448, p. 104–116. doi: 10.1016/j.virol.2013.10.005.
• Momtazi, Leva; Bagheri Fam, Shahla; Singh, Gurvinder; Hofgaard, Antje; Hakkarainen, Minna & Glomm, Wilhelm [Show all 10 contributors for this article] (2014). Synthesis, characterization, and cellular uptake of magnetic nanocarriers for cancer drug delivery. Journal of Colloid and Interface Science. ISSN 0021-9797. 433, p. 76–85. doi: 10.1016/j.jcis.2014.07.013. Show summary

  Hypothesis The absence of targetability is the primary inadequacy of conventional chemotherapy. Targeted drug delivery systems are conceptualized to overcome this challenge. We have designed a targetable magnetic nanocarrier consisting of a superparamagnetic iron oxide (SPIO) core and biocompatible and biodegradable poly(sebacic anhydride)-block-methyl ether poly(ethylene glycol) (PSA-mPEG) polymer shell. The idea is that this type of carriers should facilitate the targeting of cancer cells.

• Ulanova, Lilia; Isapour Laskookalayeh, Golnaz; Maleki, Atoosa; Fanaian, Shirin; Zhu, Kaizheng & Hofgaard, Antje [Show all 10 contributors for this article] (2014). Development of methods for encapsulation of viruses into polymeric nano- and microparticles for aquaculture vaccines. Journal of Applied Polymer Science. ISSN 0021-8995. 131(17), p. 8785–8796. doi: 10.1002/app.40714.
• Zefirova, Olga N.; Lemcke, Heiko; Lantow, Margareta; Nurieva, Evgeniya V.; Wobith, Birgit & Onishchenko, Galina E. [Show all 10 contributors for this article] (2013). Unusual tubulin-clustering ability of specifically C7-modified colchicine analogues. ChemBioChem. ISSN 1439-4227. 14(12), p. 1444–1449. doi: 10.1002/cbic.201300143.
• Lifjeld, Jan Terje; Hoenen, Antje; Johannessen, Lars Erik; Laskemoen, Terje; Lopes, Ricardo J. & Rodrigues, Pedro M. [Show all 7 contributors for this article] (2013). The Azores bullfinch (Pyrrhula murina) has the same unusual and size-variable sperm morphology as the Eurasian bullfinch (Pyrrhula pyrrhula). Biological Journal of the Linnean Society. ISSN 0024-4066. 108(3), p. 677–687. doi: 10.1111/j.1095-8312.2012.02040.x.

View all works in Cristin

• Eikrem, Wenche; Vader, Anna; Hofgaard, Antje & Edvardsen, Bente (2023). Phytoplankton in the Arctic Ocean - Species Composition and Biomass during the Nansen Legacy Arctic basin cruise, 24 Aug-26 Sep 202. Show summary

  At the southern-most station along the S-N transect, P7, the pelagic protist community was characterized by both high diversity and abundance. Large diatom species dominated the community, and large dinoflagellates and Phaeocystis pouchetii were also abundant. Moving north and into the ice, the protist community in the water column changed. Smaller organisms and heterotrophic species became more prominent. The larger diatom species became much scarcer but were still present. The community in the ice cores was dominated by pennate diatoms, but dinoflagellates and in particular the heterotrophic species were also abundant. In addition, green flagellates, cryptomonads, chrysophytes, and haptophytes were frequent. The sea-ice showed the highest chlorophyll-a values and had larger cells. In the melt ponds the salinity was low, but variable (2.8-5.7). The chlorophyll-a values there were low, and the species composition varied, and the taxa present were associated with brackish and freshwater as well as a benthic lifestyle.

• Næss, Elise; Hofgaard, Antje; Skaug, Vidar; Gulbrandsen, M.; Danielsen, Tor Erik & Grahnstedt, Svein [Show all 8 contributors for this article] (2016). Titanium dioxide nanoparticles in sunscreen penetrate the skin into viable layers of the epidermis: A clinical approach. Photodermatology, Photoimmunology & Photomedicine. ISSN 0905-4383. 32(1), p. 48–51. doi: 10.1111/phpp.12217.
• Gulbrandsen, M.; Holm, Jan Øivind; Hoenen, Antje & Skaug, Vidar (2013). Sunscreen titanium nanoparticles penetrate stratum corneum in human skin. Journal of Investigative Dermatology. ISSN 0022-202X. 133, p. S165–S165.
• Walbækken, Hanna Myhre; Eikrem, Wenche; Edvardsen, Bente; Saubrekka, Karoline & Hofgaard, Antje (2023). Dinoflagellate diversity in the Barents Sea: a comparative identification analysis. Universitetet i Oslo. Show summary

  An important group in the protist community in marine habitats are dinoflagellates. In this study the diversity of dinoflagellates in a transect of seven pelagic sea stations in the Northern Barents Sea in August 2018 and August 2019 was assessed. The two sampling periods were characterized with low and high sea-ice extent, respectively. I have studied the diversity and presence of dinoflagellate species in the sample transect using the molecular method DNA metabarcoding, and the morphological methods light microscopy (LM), and scanning electron microscopy (SEM). The results from species identification were used to observe and compare potential differences in the two sampling years. It was shown that the morphological methods were limited in identification success by little amount of material in several of the vertical net haul samples, resulting in some bias when these results were compared with DNA metabarcoding that revealed a high number of OTU (operational taxonomic unit) reads assigned to division Dinoflagellata. Species classification by DNA metabarcoding was shown to be limited by the availability of reference sequences in the curated protist ribosomal database PR2. It yielded a rough overview of the composition of dinoflagellate species in the sampling transect that could be closer examined with more time to study single OTUs. Identification done by LM and SEM revealed the presence of genera in certain stations that was not revealed in metabarcoding, and vice versa. I also found that Lugol’s solution functioned well for the preservation of cell structure for sample analysis in SEM. Climate change is shown to cause more and rapid alterations in the Arctic, and the loss of sea-ice is an important consequence of a warmer climate. Regarding interannual differences in 2018 and 2019, the morphological methods showed some differences in species composition with genus Protoperidinium more often identified in 2018 than other species, and the same for Gymnodiniales species in 2019. This could potentially show a shift in phytoplankton communities in a changing environment, although time-series are necessary to predict the future compositions of dinoflagellate species. As phytoplankton makes up the fundament for the Arctic food chain, studies of changing environmental conditions are valuable for ecological reasons.

View all works in Cristin