| 1. |
- Andersson, Annika, 1966-
(författare)
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Second language acquisition in 6- to 8-year-old native Spanish-speaking children : ERP studies of phonological awareness, semantics, and syntax
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Most people in the world and about a fifth of all school-aged Americans speak at least two languages. Nevertheless, little is known about second language (L2) processing in development, even though language proficiency is strongly related to success in almost all domains. Whereas behavioral studies of L2 acquisition in children are abundant, neurocognitive studies of L2 processing typically are limited to adults with several years of exposure, who may use general cognitive mechanisms to compensate for any difficulties in L2 processing. Research on bilingual adults suggests that age of acquisition (AoA) and proficiency have different effects on different aspects of L2 processing. The present study therefore recorded event-related brain potentials (ERPs) in order to index processes of phonological awareness (Rhyming effect: RE), semantics (N400), and syntax (LAN, P600) in bilingual and monolingual children 6-8 years of age. Even though behaviorally, bilingual children with an average AoA of 4 years had lower English proficiency than monolingual children, proficiency predicted similar differences in ERPs across groups: greater proficiency was linked with shorter latencies and higher amplitudes of all ERP components. Latency in these cases represents speed of processing while amplitude of ERP effects in children can be thought of as an indication of detection of the introduced violations. The appearance of the anterior rhyming effect, latency of the posterior rhyming effect, along with the distribution of the anterior ERP effect for phrase structure violations were related to AoA. More specifically, bilingual 6- to 8-year olds of higher English proficiency processed rhyming nonwords slower than 3- to 5-year-old monolingual children, which could have a strong impact on later vocabulary acquisition. Differences across lingualism groups in distribution of the anterior negativity elicited by phrase structure violations could indicate different neural generators for processing of syntax. Noteworthy is that differences in processing as illustrated by these ERP effects were recorded even though in both these cases bilingual children's English proficiency were within the normal range expected of monolingual children of similar age. Early acquisition was thus important for processing of rhyming and for more automatic syntactic processing as revealed by differences in the anterior negativity.
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| 2. |
- Eklund, D. Magnus, et al.
(författare)
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Homologues of the Arabidopsis thaliana SHI/STY/LRP1 genes control auxin biosynthesis and affect growth and development in the moss Physcomitrella patens
- 2010
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Ingår i: Development. - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 137:8, s. 1275-1284
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Tidskriftsartikel (refereegranskat)abstract
- The plant hormone auxin plays fundamental roles in vascular plants. Although exogenous auxin also stimulates developmental transitions and growth in non-vascular plants, the effects of manipulating endogenous auxin levels have thus far not been reported. Here, we have altered the levels and sites of auxin production and accumulation in the moss Physcomitrella patens by changing the expression level of homologues of the Arabidopsis SHI/STY family proteins, which are positive regulators of auxin biosynthesis genes. Constitutive expression of PpSHI1 resulted in elevated auxin levels, increased and ectopic expression of the auxin response reporter GmGH3pro:GUS, and in an increased caulonema/chloronema ratio, an effect also induced by exogenous auxin application. In addition, we observed premature ageing and necrosis in cells ectopically expressing PpSHI1. Knockout of either of the two PpSHI genes resulted in reduced auxin levels and auxin biosynthesis rates in leafy shoots, reduced internode elongation, delayed ageing, a decreased caulonema/chloronema ratio and an increased number of axillary hairs, which constitute potential auxin biosynthesis sites. Some of the identified auxin functions appear to be analogous in vascular and non-vascular plants. Furthermore, the spatiotemporal expression of the PpSHI genes and GmGH3pro:GUS strongly overlap, suggesting that local auxin biosynthesis is important for the regulation of auxin peak formation in non-vascular plants.
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| 3. |
- Gullberg, Marianne, et al.
(författare)
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Language-specific encoding of placement events in gestures
- 2011
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Ingår i: Event representation in language and cognition. - 978 0 521 89834 8 ; , s. 166-188
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Bokkapitel (refereegranskat)abstract
- This study focuses on the effect of the semantics of placement verbs on placement event representations. Specifically, it explores to what extent the semantic properties of habitually used verbs guide attention to certain types of spatial information. French, which typically uses a general placement verb (mettre, 'put'), is contrasted with Dutch, which uses a set of fine-grained (semi-)obligatory posture verbs (zetten, leggen, 'set/stand', 'lay'). Analysis of the concomitant gesture production in the two languages reveals a patterning toward two distinct, languagespecific event representations. The object being placed is an essential part of the Dutch representation, while French speakers instead focus only on the (path of the) placement movement. These perspectives permeate the entire placement domain regardless of the actual verb used.
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| 4. |
- Landberg, Katarina, et al.
(författare)
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The Moss Physcomitrella patens Reproductive Organ Development Is Highly Organized, Affected by the Two SHI/STY Genes and by the Level of Active Auxin in the SHI/STY Expression Domain
- 2013
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 1532-2548 .- 0032-0889. ; 162:3, s. 1406-1419
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Tidskriftsartikel (refereegranskat)abstract
- In order to establish a reference for analysis of the function of auxin and the auxin biosynthesis regulators SHORT INTERNODE/STYLISH (SHI/STY) during Physcomitrella patens reproductive development, we have described male (antheridial) and female (archegonial) development in detail, including temporal and positional information of organ initiation. This has allowed us to define discrete stages of organ morphogenesis and to show that reproductive organ development in P. patens is highly organized and that organ phyllotaxis differs between vegetative and reproductive development. Using the PpSHI1 and PpSHI2 reporter and knockout lines, the auxin reporters GmGH3(pro):GUS and PpPINA(pro): GFP-GUS, and the auxin-conjugating transgene PpSHI2(pro):IAAL, we could show that the PpSHI genes, and by inference also auxin, play important roles for reproductive organ development in moss. The PpSHI genes are required for the apical opening of the reproductive organs, the final differentiation of the egg cell, and the progression of canal cells into a cell death program. The apical cells of the archegonium, the canal cells, and the egg cell are also sites of auxin responsiveness and are affected by reduced levels of active auxin, suggesting that auxin mediates PpSHI function in the reproductive organs.
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| 5. |
- Linde, Anna-Malin, et al.
(författare)
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Early evolution of the land plant circadian clock
- 2017
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 216:2, s. 576-590
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Tidskriftsartikel (refereegranskat)abstract
- While angiosperm clocks can be described as an intricate network of interlocked transcriptional feedback loops, clocks of green algae have been modelled as a loop of only two genes. To investigate the transition from a simple clock in algae to a complex one in angiosperms, we performed an inventory of circadian clock genes in bryophytes and charophytes. Additionally, we performed functional characterization of putative core clock genes in the liverwort Marchantia polymorpha and the hornwort Anthoceros agrestis. Phylogenetic construction was combined with studies of spatiotemporal expression patterns and analysis of M. polymorpha clock gene mutants. Homologues to core clock genes identified in Arabidopsis were found not only in bryophytes but also in charophytes, albeit in fewer copies. Circadian rhythms were detected for most identified genes in M. polymorpha and A. agrestis, and mutant analysis supports a role for putative clock genes in M. polymorpha. Our data are in line with a recent hypothesis that adaptation to terrestrial life occurred earlier than previously expected in the evolutionary history of charophyte algae. Both gene duplication and acquisition of new genes was important in the evolution of the plant circadian clock, but gene loss has also contributed to shaping the clock of bryophytes.
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| 6. |
- Pederson, Eric
(författare)
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Controlled auxin biosynthesis and transport are important for developmental decisions in the early diverging land plant Physcomitrella patens
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to increase our understanding of the importance of the plant hormone auxin in land plant evolution. The role of a number of auxin regulatory network components in developmental decisions during the haploid phase of the life cycle of the model moss Physcomitrella patens, which belongs to the early diverging bryophyte group of land plants, was investigated. We show that the role of SHI/STY transcriptional activators in the regulation of auxin biosynthesis rates in seed plants is conserved in moss. The amount and rates of auxin synthesis are reduced in PpSHI knockout mutants, defects in these mutants can be mimicked by reducing active auxin in the PpSHI expression domain, and several moss homologues of YUC and TAA1/TAR genes, which encode the main auxin biosynthesis enzymes in seed plants, were activated in moss when PpSHI2 was transiently expressed. Our data reveal that these moss YUC and TAA1/TAR genes can induce auxin biosynthesis, and that their expression domains largely overlap with that of the two PpSHIs in certain stages of the moss life cycle. PpSHI2 also directly or indirectly activates homologues of genes involved in polar auxin transport (PAT) in seed plants, PpPINA, PpPINB and PpLAXB. We show that the auxin efflux function of PIN proteins have been conserved during the evolution of land plants, and that they, together with the PpSHI auxin biosynthesis regulators, are important for determining developmentally regulated decisions, such as the switch between two cell types of the filamentous stage in moss. In addition, PIN-mediated distribution of auxin synthesised in the leaves plays an important role in determining a developmentally regulated wave of cell expansion. PpSHI regulated local auxin biosynthesis is crucial for several steps in reproductive organ development, such as egg cell maturation, clearance of a canal to the egg cavity, as well as apical opening of both male and female reproductive organs allowing sperm release and entrance into the egg cavity. If polar auxin transport plays a role during these stages remains to be studied. This demonstrates that regulated distribution of auxin was operational in cell-fate decisions already in the early land plants, and that auxin has played a key role in the evolution of complex land plant structures.
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| 7. |
- Pederson, Eric R. A., et al.
(författare)
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Genome Sequencing of Pleurozium schreberi : The Assembled and Annotated Draft Genome of a Pleurocarpous Feather Moss
- 2019
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Ingår i: G3. - : Oxford University Press (OUP). - 2160-1836. ; 9:9, s. 2791-2797
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Tidskriftsartikel (refereegranskat)abstract
- The pleurocarpous feather moss Pleurozium schreberi is a ubiquitous moss species which plays a fundamental role in many terrestrial ecosystems, for instance within the boreal forest, the Earth's largest terrestrial biome, this species plays a significant role in driving ecosystem nitrogen and carbon inputs and fluxes. By hosting dinitrogen (N-2)-fixing cyanobacteria, the moss-cyanobacteria symbiosis constitutes the main nitrogen input into the ecosystem and by the high productivity and the low decomposability of the moss litter, P. schreberi contributes significantly to build-up soil organic matter, and therefore long-term C sequestration. Knowledge on P. schreberi genome will facilitate the development of 'omics' and system's biology approaches to gain a more complete understanding of the physiology and ecological adaptation of the moss and the mechanisms underpinning the establishment of the symbiosis. Here we present the de novo assembly and annotation of P. schreberi genome that will help investigating these questions. The sequencing was performed using the HiSeq X platform with Illumina paired-end and mate-pair libraries prepared with CTAB extracted DNA. In total, the assembled genome was approximately 318 Mb, while repetitive elements account for 28.42% of the genome and 15,992 protein-coding genes were predicted from the genome, of which 84.23% have been functionally annotated. We anticipate that the genomic data generated will constitute a significant resource to study ecological and evolutionary genomics of P. schreberi, and will be valuable for evo-devo investigations as well as our understanding of the evolution of land plants by providing the genome of a pleurocarpous moss.
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| 8. |
- Stuart, Rhona K., et al.
(författare)
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Bidirectional C and N transfer and a potential role for sulfur in an epiphytic diazotrophic mutualism
- 2020
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Ingår i: The ISME Journal. - : Springer Science and Business Media LLC. - 1751-7362 .- 1751-7370. ; 14:12, s. 3068-3078
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Tidskriftsartikel (refereegranskat)abstract
- In nitrogen-limited boreal forests, associations between feathermoss and diazotrophic cyanobacteria control nitrogen inputs and thus carbon cycling, but little is known about the molecular regulators required for initiation and maintenance of these associations. Specifically, a benefit to the cyanobacteria is not known, challenging whether the association is a nutritional mutualism. Targeted mutagenesis of the cyanobacterial alkane sulfonate monooxygenase results in an inability to colonize feathermosses by the cyanobacteriumNostoc punctiforme, suggesting a role for organic sulfur in communication or nutrition. Isotope probing paired with high-resolution imaging mass spectrometry (NanoSIMS) demonstrated bidirectional elemental transfer between partners, with carbon and sulfur both being transferred to the cyanobacteria, and nitrogen transferred to the moss. These results support the hypothesis that moss and cyanobacteria enter a mutualistic exosymbiosis with substantial bidirectional material exchange of carbon and nitrogen and potential signaling through sulfur compounds.
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| 9. |
- Tengvall, Katarina, 1980-, et al.
(författare)
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Bayesian model and selection signature analyses reveal risk factors for canine atopic dermatitis
- 2022
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Ingår i: Communications Biology. - : Springer Nature. - 2399-3642. ; 5:1
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Tidskriftsartikel (refereegranskat)abstract
- Canine atopic dermatitis is an inflammatory skin disease with clinical similarities to human atopic dermatitis. Several dog breeds are at increased risk for developing this disease but previous genetic associations are poorly defined. To identify additional genetic risk factors for canine atopic dermatitis, we here apply a Bayesian mixture model adapted for mapping complex traits and a cross-population extended haplotype test to search for disease-associated loci and selective sweeps in four dog breeds at risk for atopic dermatitis. We define 15 associated loci and eight candidate regions under selection by comparing cases with controls. One associated locus is syntenic to the major genetic risk locus (Filaggrin locus) in human atopic dermatitis. One selection signal in common type Labrador retriever cases positions across the TBC1D1 gene (body weight) and one signal of selection in working type German shepherd controls overlaps the LRP1B gene (brain), near the KYNU gene (psoriasis). In conclusion, we identify candidate genes, including genes belonging to the same biological pathways across multiple loci, with potential relevance to the pathogenesis of canine atopic dermatitis. The results show genetic similarities between dog and human atopic dermatitis, and future across-species genetic comparisons are hereby further motivated.
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| 10. |
- Viaene, Tom, et al.
(författare)
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Directional Auxin Transport Mechanisms in Early Diverging Land Plants
- 2014
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Ingår i: Current Biology. - : Elsevier BV. - 0960-9822 .- 1879-0445. ; 24, s. 2786-2791
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Tidskriftsartikel (refereegranskat)abstract
- The emergence and radiation of multicellular land plants was driven by crucial innovations to their body plans [1]. The directional transport of the phytohormone auxin represents a key, plant-specific mechanism for polarization and patterning in complex seed plants [2-5]. Here, we show that already in the early diverging land plant lineage, as exemplified by the moss Physcomitrella patens, auxin transport by PIN transporters is operational and diversified into ER-localized and plasma membrane-localized PIN proteins. Gain-of-function and loss-of-function analyses revealed that PIN-dependent intercellular auxin transport in Physcomitrella mediates crucial developmental transitions in tip-growing filaments and waves of polarization and differentiation in leaf-like structures. Plasma membrane PIN proteins localize in a polar manner to the tips of moss filaments, revealing an unexpected relation between polarization mechanisms in moss tip-growing cells and multicellular tissues of seed plants. Our results trace the origins of polarization and auxin-mediated patterning mechanisms and highlight the crucial role of polarized auxin transport during the evolution of multicellular land plants.
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