| 31001. |
- Petersson, Linda, et al.
(författare)
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Sprouts of shoot-clipped oak (Quercus alba and Q. robur) germinants show morphological and photosynthetic acclimation to contrasting light environments
- 2020
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Ingår i: New forests. - : Springer. - 0169-4286 .- 1573-5095. ; 51, s. 817-834
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Tidskriftsartikel (refereegranskat)abstract
- Sprouting by woody plants can increase species resilience to disturbance and foster regeneration during periods with little recruitment from seed. Though sprouting often plays a critical role in oak forest regeneration, there is little information available on sprouting capacity and sprout physiology at the seedling stage, particularly for new germinants. This study compared sprouting capacity and sprout photosynthesis of shoot-clipped germinants of two temperate oaks established in contrasting light environments. We studied the North American Quercus alba and the European Q. robur, both are in the section Quercus and appear to share similar biological and ecological requirements. Sprouting capacity for both species was enhanced under high light availability (29% more sprouts per plant), a response not previously noted for oak germinants. Seedling sprouts acclimated to high light with a 34% decrease in leaf area ratio, a 56% increase in leaf mass per area, and a 49% increase in the light-saturated maximum photosynthetic rate. Though both species appeared similarly adapted to shoot loss, a greater sprouting capacity (29% more sprouts per plant) and plant-level net photosynthesis (73% higher) was observed for Q. robur, regardless of light environment. As naturally regenerated oak seedlings in forest understories often experience disturbance or stress resulting in shoot loss or die-back, our results highlight the importance of the light environment during early plant development. Our comparison of temperate oaks from different continents should facilitate exchange of successful stand regeneration practices within the range of temperate oak forests.
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| 31002. |
- Petersson, Lisa, et al.
(författare)
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Tree species impact on understory vegetation: Vascular plant communities of Scots pine and Norway spruce managed stands in northern Europe
- 2019
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 448, s. 330-345
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Tidskriftsartikel (refereegranskat)abstract
- The tree species used in production forests can have direct implications for the understory vegetation, due to species-specific differences in the environmental conditions provided, and silviculture applied. In southern Sweden, there is an ongoing shift from even-aged managed stands of Scots pine (Pinus sylvestris) to even-aged Norway spruce (Picea abies). Here we evaluate the potential ecological consequences of these conversions by surveying the understory vascular plants, stand structural characteristics, and associated understory light levels in three age categories of Scots pine and Norway spruce stands. We quantify the extent of difference in light transmittance between the two stand types, and find large differences in understory abundance, especially among the dwarf shrubs species. Whereas bilberry (Vaccinium myrtillus) generally dominated Scots pine stand understory, the understory of Norway spruce stands was comparably sparse. Differences in vascular plant community composition indicate associated differences between the two stand types in the conditions prior to stand establishment, and subsequent understory development. In Scots pine stands the high abundance of dwarf shrubs may be outcompeting other species of vascular plants, causing a decline in species richness. In Norway spruce stands, species richness and abundance was instead apparently inhibited by limited light transmittance. In these stands generalist ruderal species and remnants from previous land use constituted a considerable part of plant species composition. Our findings suggest that the regional replacement of Scots pine with Norway spruce will lead to a noticeable loss of understory diversity, for which the decline in Vaccinium species will be the most prominent. We discuss the associated implications of our results for forest ecosystem services, and how shortened rotation lengths in Norway spruce stands would compound these impacts.
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| 31003. |
- Petersson, Maria, et al.
(författare)
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Oxytocin and Cortisol Levels in Dog Owners and Their Dogs Are Associated with Behavioral Patterns : An Exploratory Study
- 2017
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Ingår i: Frontiers in Psychology. - : Frontiers Media S.A.. - 1664-1078. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- We have previously shown that dog–owner interaction results in increasing oxytocin levels in owners and dogs, decreasing cortisol levels in owners but increasing cortisol levels in dogs. The present study aimed to further investigate whether oxytocin and cortisol levels in the previously tested owners and dogs were associated with their behaviors during the interaction experiment. Ten female volunteer dog–owners and their male Labrador dogs participated in a 60 min interaction experiment with interaction taking place during 0–3 min and blood samples for analysis of oxytocin and cortisol were collected at 0, 1, 3, 5, 15, 30, and 60 min. The entire experiment was videotaped and the following variables were noted; the different types (stroking, scratching, patting and activating touch, i.e., scratching and patting combined) as well as the frequency of touch applied by the owner, the number of times the owner touched her dog, the dog’s positions and time spent in each position. Correlations were analyzed between the behavioral variables and basal oxytocin levels, maximum oxytocin levels, delta oxytocin levels, basal cortisol levels and cortisol levels at 15 min. Owners with low oxytocin levels before and during the interaction touched their dogs more frequently (0 min: Rs = −0.683, p = 0.042; oxytocin maximum: Rs = −0.783, p = 0.013). The lower the dogs’ oxytocin levels during the interaction, the more stroking they received (Rs = −0.717, p = 0.041). The more frequently activating touch was applied by the owner, the higher the dogs’ cortisol levels became (15 min: Rs = 0.661, p = 0.038). The higher the owners’ maximum oxytocin level the fewer position changes the dogs made (Rs = −0.817, p = 0.007) and the shorter time they spent sitting (Rs = −0.786, p = 0.036), whereas the higher the owners’ basal cortisol levels, the longer time the dogs spent standing (0 min: Rs = 0.683, p = 0.041). In conclusion, oxytocin and cortisol levels, both in dogs and in their owners, are associated with the way the owners interact with their dogs and also with behaviors caused by the interaction.
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| 31004. |
- Petersson, Sara, et al.
(författare)
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An auxin gradient and maximum in the arabidopsis root apex shown by high-resolution cell-specific analysis of IAA distribution and synthesis
- 2009
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Ingår i: The Plant Cell. - : Oxford University Press (OUP). - 1040-4651 .- 1532-298X. ; 21:6, s. 1659-1668
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Tidskriftsartikel (refereegranskat)abstract
- Local concentration gradients of the plant growth regulator auxin (indole-3-acetic acid [IAA]) are thought to instruct the positioning of organ primordia and stem cell niches and to direct cell division, expansion, and differentiation. High-resolution measurements of endogenous IAA concentrations in support of the gradient hypothesis are required to substantiate this hypothesis. Here, we introduce fluorescence-activated cell sorting of green fluorescent protein-marked cell types combined with highly sensitive mass spectrometry methods as a novel means for analyses of IAA distribution and metabolism at cellular resolution. Our results reveal the presence of IAA concentration gradients within the Arabidopsis thaliana root tip with a distinct maximum in the organizing quiescent center of the root apex. We also demonstrate that the root apex provides an important source of IAA and that cells of all types display a high synthesis capacity, suggesting a substantial contribution of local biosynthesis to auxin homeostasis in the root tip. Our results indicate that local biosynthesis and polar transport combine to produce auxin gradients and maxima in the root tip.
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| 31005. |
- Petersson, Sara, et al.
(författare)
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Cell-type specific metabolic profiling of Arabidopsis thaliana protoplasts as a tool for plant systems biology
- 2015
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Ingår i: Metabolomics. - : Springer Science and Business Media LLC. - 1573-3882 .- 1573-3890. ; 11, s. 1679-1689
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Tidskriftsartikel (refereegranskat)abstract
- Flow cytometry combined with cell sorting of protoplasts has previously been used successfully for transcript profiling of the Arabidopsis thaliana root. We have developed the technique further, and in this paper we present a robust and reliable method for metabolite profiling in specific cell types isolated from Arabidopsis roots. The method uses a combination of fluorescence-activated cell sorting and gas chromatography-time of flight-mass spectrometry analysis. Cortical and endodermal cells from the green fluorescent protein (GFP)-expressing enhancer trap line J0571 were analysed and compared with non-GFP-expressing cells and intact root tissue. Of the metabolites identified, several showed significant differences in concentration between cell types. Multivariate statistical analysis was used to compare metabolite patterns between cell and tissue types, showing that the patterns differed substantially. Isolation of specific cell populations combined with highly sensitive MS-analysis will be a powerful tool for future studies of plant metabolism, and can also be combined with transcript and protein profiling for in-depth analyses of cellular processes.
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| 31006. |
- Petersson, Sara
(författare)
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Distribution and regulation of auxin in Arabidopsis root cells
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The plant hormone auxin (IAA) coordinates many of the important processes in plant development. For example, IAA is critical for normal embryogenesis, root development, cell elongation, and the tropic responses such as gravitropism and phototropism. IAA gradients are established and maintained in many tissues and it is thought that these gradients act as developmental cues, determining the fate of cells and tissues. Descriptions of auxin distribution patterns with cellular resolution have previously been based solely on visual characterisation of auxin responsive reporter constructs. Measurements of the hormone gradient itself have been made in cambial sections of hybrid aspen and Pine, although even in this study, the measurements were not truly at cellular resolution. In this thesis, I describe the measurement of IAA levels in the Arabidopsis root with cellular resolution. By combining the use of Arabidopsis lines expressing cellspecific GFP, Fluorescent Activated Flow Cytometry, and high-resolution mass spectrometry, I have provided the first analytical evidence for the presence of an IAA gradient in the Arabidopsis root apex. The work has enabled the development of an auxin distribution map for the root with cellular resolution. The IAA content of cells is actively regulated in order to maintain the IAA gradient. This regulation has been shown to be achieved through a combination of active transport and de novo biosynthesis. It has been proposed that IAA catabolism and conjugation also contribute to the regulation of hormone levels. In this thesis, I present data supporting the hypothesis that catabolism, by converting IAA into its major inactive catabolite oxIAA, contributes to the regulation of the levels of free IAA. I also present data showing a role for the plant hormone cytokinin in the dynamic regulation of IAA biosynthesis in response to changing developmental and environmental conditions.
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| 31007. |
- Petersson Troije, Charlotte, et al.
(författare)
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Outdoor Office Work : An Interactive Research Project Showing the Way Out
- 2021
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Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The physical boundaries of office work have become increasingly flexible. Work is conducted at multiple locations outside the office, such as at clients' premises, at home, in cafés, or when traveling. However, the boundary between indoor and outdoor environment seems to be strong and normative regarding how office work is performed. The aim of this study was to explore how office work may be conducted outdoors, understanding how it is being experienced by office employees and identifying its contextual preconditions. Based on a two-year interactive research project, the study was conducted together with a Swedish municipality. Fifty-eight participants engaged in the collaborative learning process, including 40 half-day workshops and reflective group discussions, co-interviews, and participants' independent experimentation of bringing work activities outdoors. Data was collected via interviews, group discussions and a custom-made mobile application. The results showed that a wide range of work activities could be done outdoors, both individually and in collaboration with others. Outdoor work activities were associated with many positive experiences by contributing to a sense of well-being, recovery, autonomy, enhanced cognition, better communication, and social relations, but also with feelings of guilt and illegitimacy. Conditions of importance for outdoor office work to happen and function well were found in the physical environment, where proximity to urban greenspaces stood out as important, but also in the sociocultural and organizational domains. Of crucial importance was managers' attitudes, as well as the overall organizational culture on this idea of bringing office work outdoors. To conclude, if working life is to benefit from outdoor office work, leaders, urban planners and policymakers need to collaborate and show the way out.
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| 31008. |
- Petitt, Andrea
(författare)
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Cowboy masculinities in human-animal relations on a cattle ranch
- 2013
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Ingår i: Elore. - 1456-3010. ; 20, s. 67-82
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Tidskriftsartikel (refereegranskat)abstract
- The cowboy has come to be a symbol of the ultimate masculine, and his image is often used to describe the archetype of heterosexual macho masculinity. Nevertheless, this paper shows that contemporary cowboys on a working cattle ranch in western Canada display and value alternative cowboy masculinities characterised by responsibility, calmness, technical finesse, and sensitivity. This paper problematises human-animal relations between cowboys, horses and cows that meet on a daily basis on a working cattle ranch. The focus is on how masculinities play a part in the interaction between cowboy and horse/cow in everyday life on the ranch and how animals are used to construct or display different masculinities. Participant observation among a cowboy crew, as well as interviews, were used to collect empirical data for the study. Drawing on posthumanist understandings of embodied experience, non-binary human-animal relations and multiple masculinities, this paper underlines an expansion of non-binary analytical frameworks. The paper concludes that while the same species can offer a range of relations leading to the possibility of displaying different masculinities, different categories of animals are instrumental in different ways in the construction of alternative and additional masculinities among the cowboys.
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| 31009. |
- Petitt, Andrea, 1981-
(författare)
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Women's cattle ownership in Botswana : Rebranding gender relations?
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cattle are often portrayed as a male affair in Botswana. However, venturing out into the Kalahari countryside to scratch the surface of this state of affairs, another picture emerges. There are in fact many women from different socioeconomic background who own, manage and work with cattle in different ways, and their farming is defined by both the connection to the EU beef market and interlinked local processes of power. Cattle are ever-present in Botswana and play a paramount role in the economy, in politics and in the rural landscape of the country, as well as in many people’s cultural identity, kinship relations and everyday routines.I study women’s involvement in cattle production in Ghanzi District to think about how peoples’ relations to certain livestock species produce, reproduce and challenge established patterns of material and social relations. More specifically I investigate how access and claims to livestock are defined by intersections of gender, ethnicity, race and class within broader contexts associated with the commercialisation of livestock production.The objective of this thesis is to explore how different women are able to benefit from their cattle ownership in terms of their social positions and material welfare in Botswana within the broader political, economic and sociocultural contexts associated with the commercial beef industry. Through ethnographic fieldwork and an intersectional analysis of gendered property relations to grazing land and cattle, I show how women do benefit from both subsistence products and monetary income from cattle sales. An increased need for cash together with the possibility to sell cattle stimulated by Botswana’s beef trade with the EU have motivated women to seek control over cattle. There are women who, encouraged by gender equality messages from the Ministry of Gender Affairs, make use of the government’s loans and grants designed to facilitate entrepreneurship to start up their own cattle operations and make claims to the cattle market. Many of these women, who have control over their cattle also benefit in terms of social status and a number of those women who engage in cattle production in ways seen as new and different speak of more equal gender relations.
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| 31010. |
- Petrén, Hampus, et al.
(författare)
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Evolution of floral scent in relation to self-incompatibility and capacity for autonomous self-pollination in the perennial herb Arabis alpina
- 2021
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 127:6, s. 737-747
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: The transition from outcrossing to selfing is a frequent evolutionary shift in flowering plants and is predicted to result in reduced allocation to pollinator attraction if plants can self-pollinate autonomously. The evolution of selfing is associated with reduced visual floral signalling in many systems, but effects on floral scent have received less attention. We compared multiple populations of the arctic-alpine herb Arabis alpina (Brassicaceae), and asked whether the transition from self-incompatibility to self-compatibility has been associated with reduced visual and chemical floral signalling. We further examined whether floral signalling differ between self-compatible populations with low and high capacity for autonomous self-pollination, as would be expected if benefits of signalling decrease with reduced dependence on pollinators for pollen transfer. Methods: In a common garden we documented flower size and floral scent emission rate and composition in eight self-compatible and nine self-incompatible A. alpina populations. These included self-compatible Scandinavian populations with high capacity for autonomous self-pollination, self-compatible populations with low capacity for autonomous self-pollination from France and Spain, and self-incompatible populations from Italy and Greece. Key Results: The self-compatible populations produced smaller and less scented flowers than the self-incompatible populations. However, flower size and scent emission rate did not differ between self-compatible populations with high and low capacity for autonomous self-pollination. Floral scent composition differed between self-compatible and self-incompatible populations, but also varied substantially among populations within the two categories. Conclusions: Our study demonstrates extensive variation in floral scent among populations of a geographically widespread species. Contrary to expectation, floral signalling did not differ between self-compatible populations with high and low capacity for autonomous self-pollination, indicating that dependence on pollinator attraction can only partly explain variation in floral signalling. Additional variation may reflect adaptation to other aspects of local environments, genetic drift, or a combination of these processes.
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