| 1. |
- Boije, Henrik, et al.
(author)
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Alternative Splicing of the Chromodomain Protein Morf4l1 Pre-mRNA Has Implications on Cell Differentiation in the Developing Chicken Retina
- 2013
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In: Journal of Molecular Neuroscience. - : Springer Science and Business Media LLC. - 0895-8696 .- 1559-1166. ; 51:2, s. 615-628
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Journal article (peer-reviewed)abstract
- The proliferation, cell cycle exit and differentiation of progenitor cells are controlled by several different factors. The chromodomain protein mortality factor 4-like 1 (Morf4l1) has been ascribed a role in both proliferation and differentiation. Little attention has been given to the existence of alternative splice variants of the Morf4l1 mRNA, which encode two Morf41l isoforms: a short isoform (S-Morf4l1) with an intact chromodomain and a long isoform (L-Morf4l1) with an insertion in or in the vicinity of the chromodomain. The aim of this study was to investigate if this alternative splicing has a function during development. We analysed the temporal and spatial distribution of the two mRNAs and over-expressed both isoforms in the developing retina. The results showed that the S-Morf4l1 mRNA is developmentally regulated. Over-expression of S-Morf4l1 using a retrovirus vector produced a clear phenotype with an increase of early-born neurons: retinal ganglion cells, horizontal cells and cone photoreceptor cells. Over-expression of L-Morf4l1 did not produce any distinguishable phenotype. The over-expression of S-Morf4l1 but not L-Morf4l1 also increased apoptosis in the infected regions. Our results suggest that the two Morf4l1 isoforms have different functions during retinogenesis and that Morf4l1 functions are fine-tuned by developmentally regulated alternative splicing. The data also suggest that Morf4l1 contributes to the regulation of cell genesis in the retina.
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| 2. |
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| 3. |
- Boije, Henrik, et al.
(author)
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Forkheadbox N4 (FoxN4) triggers context-dependent differentiation in the developing chick retina and neural tube
- 2013
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In: Differentiation. - : Elsevier BV. - 0301-4681 .- 1432-0436. ; 85:1-2, s. 11-19
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Journal article (peer-reviewed)abstract
- FoxN4, a forkhead box transcription factor, is expressed in the chicken eye field and in retinal progenitor cells (RPCs) throughout development. FoxN4 labelling overlapped with that of Pax6 and Sox2, two crucial transcription factors for RPCs. Later, during neurogenesis in the retina, some cells were intensely and transiently labelled for FoxN4. These cells co-labelled for Lim1, a transcription factor expressed in early-born horizontal cells. The result suggests that high levels of FoxN4 combined with expression of Lim1 define a population of RPCs committed to the horizontal cell fate prior to their last apical mitosis. As these prospective horizontal cells develop, their FoxN4 expression is down-regulated. Previous results suggested that FoxN4 is important for the generation of horizontal and amacrine cells but that it is not sufficient for the generation of horizontal cells (Li et al., 2004). We found that over-expression of FoxN4 in embryonic day 3 chicken retina could activate horizontal cell markers Prox1 and Lim1, and that it generated numerous and ectopically located horizontal cells of both main subtypes. However, genes expressed in photoreceptors, amacrine and ganglion cells were also activated, indicating that FoxN4 triggered the expression of several differentiation factors. This effect was not exclusive for the retina but was also seen when FoxN4 was over-expressed in the mesencephalic neural tube. Combining the results from over-expression and wild-type expression data we suggest a model where a low level of FoxN4 is maintained in RPCs and that increased levels during a restricted period trigger neurogenesis and commitment of RPCs to the horizontal cell fate.
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| 4. |
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| 5. |
- Boije, Henrik, et al.
(author)
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Pax2 Is Expressed in a Subpopulation of Muller Cells in the Central Chick Retina
- 2010
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In: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 239:6, s. 1858-1866
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Journal article (peer-reviewed)abstract
- Muller cells in the chick retina are generally thought to be a homogeneous population. We show that the transcription factor Pax2 is expressed by Muller cells in the central chick retina and its expression was first observed at stage 32 (embryonic day [E] 7.5). Birth-dating indicated that the majority of Pax2-positive Muller cells are generated between stage 29 and 33 (E5.5-E8). At stage 42 (E16), several Muller cell markers, such as Sox2 and 2M6, had reached the peripheral retina, while the Pax2 labeling extended approximately half-way. A similar pattern was maintained in the 6-month-old chicken. Neither the Pax2-positive nor the Pax2-negative Muller cells could be specifically associated to proliferative responses in the retina induced by growth factors or N-methyl-D-aspartate. Pax2 was not detected in Muller cells in mouse, rat, guinea-pig, rabbit, or pig retinas; but the zebrafish retina displayed a similar pattern of central Pax2-expressing Muller cells.
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| 6. |
- de Jong, Yde, et al.
(author)
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PESI - a taxonomic backbone for Europe
- 2015
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In: Biodiversity Data Journal. - 1314-2836 .- 1314-2828. ; 3, s. 1-51
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Journal article (peer-reviewed)abstract
- Reliable taxonomy underpins communication in all of biology, not least nature conservation and sustainable use of ecosystem resources. The flexibility of taxonomic interpretations, however, presents a serious challenge for end-users of taxonomic concepts. Users need standardised and continuously harmonised taxonomic reference systems, as well as high-quality and complete taxonomic data sets, but these are generally lacking for non-specialists. The solution is in dynamic, expertly curated web-based taxonomic tools.The Pan-European Species-directories Infrastructure (PESI) worked to solve this key issue by providing a taxonomic e-infrastructure for Europe. It strengthened the relevant social (expertise) and information (standards, data and technical) capacities of five major community networks on taxonomic indexing in Europe, which is essential for proper biodiversity assessment and monitoring activities. The key objectives of PESI were: 1) standardisation in taxonomic reference systems, 2) enhancement of the quality and completeness of taxonomic data sets and 3) creation of integrated access to taxonomic information.This paper describes the results of PESI and its future prospects, including the involvement in major European biodiversity informatics initiatives and programs.
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| 7. |
- Ring, Henrik, et al.
(author)
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Increased A-to-I RNA editing of the transcript for GABAA receptor subunit α3 during chick retinal development
- 2010
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In: Visual Neuroscience. - : Cambridge University Press. - 0952-5238 .- 1469-8714. ; 27:5-6, s. 149-157
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Journal article (peer-reviewed)abstract
- Adenosine-to-inosine (A-to-I) RNA editing is a cotranscriptional or posttranscriptional gene regulatory mechanism that increases the diversity of the proteome in the nervous system. Recently, the transcript for GABA type A receptor subunit α3 was found to be subjected to RNA editing. The aim of this study was to determine if editing of the chicken α3 subunit transcript occurs in the retina and if the editing is temporally regulated during development. We also raised the question if editing of the α3 transcript was temporally associated with the suggested developmental shift from excitation to inhibition in the GABA system. The editing frequency was studied by using Sanger and Pyrosequencing, and to monitor the temporal aspects, we studied the messenger RNA expression of the GABAA receptor subunits and chloride pumps, known to be involved in the switch. The results showed that the chick α3 subunit was subjected to RNA editing, and its expression was restricted to cells in the inner nuclear and ganglion cell layer in the retina. The extent of editing increased during development (after embryonic days 8–9) concomitantly with an increase of expression of the chloride pump KCC2. Expression of several GABAA receptor subunits known to mediate synaptic GABA actions was upregulated at this time. We conclude that editing of the chick GABAA subunit α3 transcript in chick retina gives rise to an amino acid change that may be of importance in the switch from excitatory to inhibitory receptors.
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| 8. |
- André, Carl, 1958, et al.
(author)
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Population structure in Atlantic cod in the eastern North Sea - Skagerrak - Kattegat: early life stage dispersal and adult migration
- 2016
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In: BMC Research Notes. - : Springer Science and Business Media LLC. - 1756-0500. ; 9:63
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Journal article (peer-reviewed)abstract
- Background: In marine fish species, where pelagic egg and larvae drift with ocean currents, population structure has been suggested to be maintained by larval retention due to hydrographic structuring and by homing of adult fish to natal areas. Whilst natal homing of adults has been demonstrated for anadromous and coral reef fishes, there are few documented examples of philopatric migration in temperate marine fish species. Results: Here, we demonstrate temporally stable genetic differentiation among spawning populations of Atlantic cod (Gadus morhua L.), and present genetic and behavioural evidence for larval drift and philopatric migration in the eastern North Sea-Skagerrak-Kattegat area. We show that juvenile cod collected in the eastern Skagerrak and central Kattegat are genetically similar to cod from offshore spawning areas in the eastern North Sea. Genetic assignment of individual 2-5 year old fish indicates that cod residing at, or migrating towards, spawning areas in Kattegat and the North Sea display philopatric behaviours. Conclusions: Together these findings suggest a loop between spawning, larval drift and adult return-migrations to spawning areas and underlines that both oceanographic processes and migratory behaviour in the adult phase may be important for stock separation and integrity in marine temperate fishes such as Atlantic cod. © 2016 André et al.
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| 9. |
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| 10. |
- Blixt, Maria K. E., et al.
(author)
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Zinc finger gene nolz1 regulates the formation of retinal progenitor cells and suppresses the Lim3/Lhx3 phenotype of retinal bipolar cells in chicken retina
- 2018
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In: Developmental Dynamics. - : WILEY. - 1058-8388 .- 1097-0177. ; 247:4, s. 630-641
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Journal article (peer-reviewed)abstract
- Background: The zinc-finger transcription factor Nolz1 regulates spinal cord neuron development by interacting with the transcription factors Isl1, Lim1, and Lim3, which are also important for photoreceptors, horizontal and bipolar cells during retinal development. We, therefore, studied Nolz1 during retinal development.Results: Nolz1 expression was seen in two waves during development: one early (peak at embryonic day 3-4.5) in retinal progenitors and one late (embryonic day 8) in newly differentiated cells in the inner nuclear layer. Overexpression and knockdown showed that Nolz1 decreases proliferation and stimulates cell cycle withdrawal in retinal progenitors with effects on the generation of retinal ganglion cells, photoreceptors, and horizontal cells without triggering apoptosis. Overexpression of Nolz1 gave more p27 positive cells. Sustained overexpression of Nolz1 in the retina gave fewer Lim3/Lhx3 bipolar cells.Conclusions: We conclude that Nolz1 has multiple functions during development and suggest a mechanism in which Nolz1 initially regulates the proliferation state of the retinal progenitor cells and then acts as a repressor that suppresses the Lim3/Lhx3 bipolar cell phenotype at the time of bipolar cell differentiation.
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