| 1. |
- Power, M. J., et al.
(author)
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Changes in fire regimes since the Last Glacial Maximum : an assessment based on a global synthesis and analysis of charcoal data
- 2008
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In: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 30:7-8, s. 887-907
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Journal article (peer-reviewed)abstract
- Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
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| 2. |
- Power, Deborah M, et al.
(author)
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The molecular and endocrine basis of flatfish metamorphosis
- 2008
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In: Reviews in Fisheries Science. - : Informa UK Limited. - 1064-1262 .- 1547-6553. ; 16:S1, s. 93-109
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Journal article (peer-reviewed)abstract
- A significant component of aquaculture is the production of good quality larvae, and, in the case of flatfish, this is tied up with the change from a symmetric larva to an asymmetric juvenile. Despite the pioneering work carried out on the metamorphosis of the Japanese flounder (Paralichthys olivaceus) and summer flounder (Paralichthys dentatus), the underlying molecular basis of flatfish metamorphosis is still relatively poorly characterized. It is a thyroid hormone (TH) driven process, and the role of other hormones in the regulation of the process along with the interplay of abiotic factors are still relatively poorly characterized as is the extent of tissue and organ remodeling, which underlie the profound structural and functional modifications that accompany the larval/juvenile transition. The isolation of genes for hormones, receptors, binding proteins, and other accessory factors has provided powerful tools with which to pursue this question. The application of molecular methodologies such as candidate gene approaches and microarray analysis coupled to functional genomics has started to contribute to understanding the complexity of tissue and organ modifications that accompany flatfish metamorphosis. A better understanding of the biology of normal metamorphosis is essential to identify factors contributing to abnormal metamorphosis.
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| 11. |
- Bugge, Markus M, 1974-
(author)
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Creative Distraction : The Digital Transformation of the Advertising Industry
- 2009
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Doctoral thesis (other academic/artistic)abstract
- This thesis is primarily based on a case study on how the Internet affects the advertising industry in Oslo, Norway, and on how the digitization of advertising adds to our understanding of the geography of innovation and urban and regional development. The study argues that the Internet fundamentally changes and challenges the advertising industry, and that advertising merges into market communication and even user experience and product development. The interactive nature of the Internet and its parallel social and commercial worlds contribute to transcend the role of a traditional medium and to coalescence between production and consumption. Despite the fact that those involved in online and traditional advertising are located close to each other in Oslo, the extent of collective learning, knowledge externalities and innovation has been scarce. The study shows that the creative destruction of this industrial sector is ignited by actors outside the traditional advertising industry. Due to path dependency along one-way mass communication media incumbents within the advertising industry have left room for new actors, such as web agencies and technology consultants, to explore and take market share in online market communication services. The reconfiguration of market communication is regarded as the result of an industry mutation across advertising and ICT, and creates a need for bridging skills and competencies across creative, strategic and interactive domains. The implications of such an industry mutation across diverse sectors are used to discuss the evolutionary potential of the related variety perspective. The study argues that localized industrial change may be conceptualised in terms of a cyclical relationship between externalities from localisation economies and urbanisation economies respectively. The implications of the findings from the case study are in this way used to discuss more general drivers of urban and regional development.
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| 12. |
- Einarsdottir, Ingibjörg, 1951, et al.
(author)
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Isolation of Atlantic halibut pituitary hormones by continuous-elution electrophoresis followed by fingerprint identification, and assessment of growth hormone content during larval development
- 2007
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In: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480. ; 150:2, s. 355-363
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Journal article (peer-reviewed)abstract
- Continuous-elution electrophoresis (CEE) has been applied to separate putative hormones from adult Atlantic halibut pituitaries. Soluble proteins were separated by size and charge on Model 491 Prep Cell (Bio-Rad), where the homogenate runs through a cylindrical gel, and protein fractions are collected as they elute from the matrix. Protein fractions were assessed by SDS–PAGE and found to contain purified proteins of molecular size from 10 to 33 kDa. Fractions containing proteins with molecular weights of approximately 21, 24, 28 and 32 kDa, were identified as putative growth hormone (GH), prolactin, somatolactin and gonadotropins, respectively. These were analyzed further by mass spectrometry and identified with peptide mass protein fingerprinting. The CEE technique was used successfully for purification of halibut GH with a 5% yield, and appears generally well suited to purify species-specific proteins often needed for research in comparative endocrinology, including immunoassay work. Thus, the GH obtained was subsequently used as standards and iodination label in a homologous radioimmunoassay, applied to analyze GH content through larval development in normally and abnormally metamorphosing larvae. As GH is mainly found in the pituitary, GH contents were analyzed in tissue extracts from the heads only. The pituitary GH content increases proportionally to increased larval weight from first feeding to metamorphic climax. No difference in relative GH content was found between normal and abnormal larvae and it still remains to be established if GH has a direct role in metamorphosis.
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| 13. |
- Einarsdottir, Ingibjörg, 1951, et al.
(author)
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Thyroid and pituitary gland development from hatching through metamorphosis of a teleost flatfish, the Atlantic halibut
- 2006
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In: Anatomy and Embryology. - : Springer Science and Business Media LLC. - 0340-2061 .- 1432-0568. ; 211:1, s. 47-60
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Journal article (peer-reviewed)abstract
- Fish larval development, not least the spectacular process of flatfish metamorphosis, appears to be under complex endocrine control, many aspects of which are still not fully elucidated. In order to obtain data on the functional development of two major endocrine glands, the pituitary and the thyroid, during flatfish metamorphosis, histology, immunohistochemistry and in situ hybridization techniques were applied on larvae of the Atlantic halibut (Hippoglossus hippoglossus), a large, marine flatfish species, from hatching through metamorphosis. The material was obtained from a commercial hatchery. Larval age is defined as day-degrees (D degrees=accumulated daily temperature from hatching). Sporadic thyroid follicles are first detected in larvae at 142 D degrees (27 days post-hatch), prior to the completion of yolk sack absorption. Both the number and activity of the follicles increase markedly after yolk sack absorption and continue to do so during subsequent development. The larval triiodothyronine (T-3) and thyroxine (T-4) content increases, subsequent to yolk absorption, and coincides with the proliferation of thyroid follicles. A second increase of both T-3 and T-4 occurs around the start of metamorphosis and the T-3 content further increases at the metamorphic climax. Overall, the T-3 content is lower than T-4. The pituitary gland can first be distinguished as a separate organ at the yolk sack stage. During subsequent development, the gland becomes more elongated and differentiates into neurohypophysis (NH), pars distalis (PD) and pars intermedia (PI). The first sporadic endocrine pituitary cells are observed at the yolk sack stage, somatotrophs (growth hormone producing cells) and somatolactotrophs (somatolactin producing cells) are first observed at 121 D degrees (23 days post-hatch), and lactotrophs (prolactin producing cells) at 134 D degrees (25 days post-hatch). Scarce thyrotrophs are evident after detection of the first thyroid follicles (142 D degrees), but coincident with a phase in which follicle number and activity increase (260 D degrees). The somatotrophs are clustered in the medium ventral region of the PD, lactotrophs in the anterior part of the PD and somatolactotrophs are scattered in the mid and posterior region of the pituitary. At around 600 D degrees, coinciding with the start of metamorphosis, somatolactotrophs are restricted to the interdigitating tissue of the NH. During larval development, the pituitary endocrine cells become more numerous. The present data on thyroid development support the notion that thyroid hormones may play a significant role in Atlantic halibut metamorphosis. The time of appearance and the subsequent proliferation of pituitary somatotrophs, lactotrophs, somatolactotrophs and thyrotrophs indicate at which stages of larval development and metamorphosis these endocrine cells may start to play active regulatory roles.
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| 14. |
- Hildahl, Jon, 1976, et al.
(author)
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CHARACTERIZATION OF THE GROWTH HORMONE – INSULIN-LIKE GROWTH FACTOR I SYSTEM DURING ATLANTIC HALIBUT METAMORPHOSIS
- 2006
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In: 7th International Congress on the Biology of Fish, Book of Abstracts.
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Conference paper (other academic/artistic)abstract
- The GH-IGF-I system is critical for proper growth and development in fish and thus is likely to play a role in the control of flatfish metamorphosis.. In order to characterize the role of GH and IGF-I in Atlantic halibut development, hormonal content (GH and IGF-I RIA) and receptor gene expression (GHR and IGF-IR QPCR) was assessed during normal and abnormal metamorphosis GH larval head content increases throughout normal metamorphosis in parallel with larval weight. The full-length GH receptor (hhGHRfl) mRNA and IGF-I protein levels change in parallel and in a stage-specific manner, with an increase at the onset of metamorphosis followed by down-regulation. Two isoforms of the IGF-I receptor are regulated differently; isoform one (hhIGF-IR1) mRNA increases from pre-metamorphosis to the post-metamorphic juvenile stage, while isoform 2 (hhIGF-IR2) mRNA is highest at early pre-metamorphosis and decreases prior to the onset of metamorphosis. In larvae experiencing arrested development, mRNA levels for hhGHRfl and hhIGF-IR1 and IGF-I larval content are depressed relative to normal individuals, whereas GH content, hhIGF-IR2 mRNA levels and weight are not changed. Increased hhGHRfl mRNA and IGF-I protein levels at the onset of metamorphosis suggest that tissue sensitivity to GH increases during metamorphosis while tissue sensitivity to IGF-I does not change. The data provide new evidence suggesting that GHR and IGF-IR levels may be of critical importance for metamorphic success in Atlantic halibut. Funded by the EU and FORMAS.
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| 15. |
- Hildahl, Jon, 1976, et al.
(author)
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Involvement of growth hormone-insulin-like growth factor I system in cranial remodeling during halibut metamorphosis as indicated by tissue- and stage-specific receptor gene expression and the presence of growth hormone receptor protein.
- 2008
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In: Cell and tissue research. - : Springer Science and Business Media LLC. - 0302-766X .- 1432-0878. ; 332:2, s. 211-25
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Journal article (peer-reviewed)abstract
- The role of growth hormone (GH) and insulin-like growth factor-I (IGF-I) in the tissue remodeling associated with the transition of a symmetrical larva to an asymmetrical juvenile during flatfish metamorphosis is unknown. In order to investigate the potential role of these hormones in the remodeling of cranial bone and soft tissue that accompanies eye migration during metamorphosis of Atlantic halibut (Hippoglossus hippoglossus) larvae, tissue-specific gene expression was monitored by in situ hybridization for Atlantic halibut type I growth hormone receptor (hhGHR), type II hhGHR, and insulin-like growth factor-I receptor (hhIGF-IR). Polyclonal antibody generated against the extracellular domain of type I hhGHR was used for the immunohistochemical localization of type I GHR protein. Type I hhGHR, type II hhGHR, and hhIGF-IR mRNA were expressed in fibroblasts, frontal bone osteocytes, and dorsal chondrocytes at the onset of metamorphosis (stage 8), during metamorphic climax (stage 9), and in fully metamorphosed juveniles (stage 10). Type I GHR protein showed similar expression patterns to those of type I hhGHR mRNA, except in chondrocytes in which little GHR protein was detected. The localization of GHR and IGF-IR transcripts and GHR protein in cranial structures that undergo remodeling is intriguing and suggests that, in addition to thyroid hormones, the GH-IGF-I system is involved in morphological transformations during metamorphosis in Atlantic halibut.
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| 16. |
- Morgado, Isabel, et al.
(author)
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Hormone affinity and fibril formation of piscine transthyretin : The role of the N-terminal
- 2008
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In: Molecular and Cellular Endocrinology. - : Elsevier Ireland Ltd. - 0303-7207 .- 1872-8057. ; 295:1-2, s. 48-58
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Journal article (peer-reviewed)abstract
- Transthyretin (TTR) transports thyroid hormones (THs), thyroxine (T4) and triiodothyronine (T3) in the blood of vertebrates. TH-binding sites are highly conserved in vertebrate TTR, however, piscine TTR has a longer N-terminus which is thought to influence TH-binding affinity and may influence TTR stability. We produced recombinant wild type sea bream TTR (sbTTRWT) plus two mutants in which 6 (sbTTRM6) and 12 (sbTTRM12) N-terminal residues were removed. Ligand-binding studies revealed similar affinities for T3 (Kd=10.6+/-1.7nM) and T4 (Kd=9.8+/-0.97nM) binding to sbTTRWT. Affinity for THs was unaltered in sbTTRM12 but sbTTRM6 had poorer affinity for T4 (Kd=252.3+/-15.8nM) implying that some residues in the N-terminus can influence T4 binding. sbTTRM6 inhibited acid-mediated fibril formation in vitro as shown by fluorometric measurements using thioflavine T. In contrast, fibril formation by sbTTRM12 was significant, probably due to decreased stability of the tetramer. Such studies also suggested that sbTTRWT is more resistant to fibril formation than human TTR.
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