| 1. |
- Hagman, Anna, et al.
(författare)
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Obstetric Outcomes in Women with Turner Karyotype.
- 2011
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 96:11, s. 3475-3482
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Tidskriftsartikel (refereegranskat)abstract
- Context: Women with Turner syndrome (TS) have high risk of cardiovascular complications and hypertensive disorders. Few studies have analyzed obstetric outcome in women with TS. Objective: This study compared obstetric outcome in women with TS karyotype with women in the general population. Design: The Swedish Genetic Turner Register was cross-linked with the Swedish Medical Birth Register between 1973 and 2007. Obstetric outcome in singletons was compared with a reference group of 56,000 women from the general population. Obstetric outcome in twins was described separately. Results: A total of 202 singletons and three sets of twins were born to 115 women with a TS karyotype that was unknown in 52% at time of pregnancy. At first delivery, TS women of singletons were older than controls (median 30 vs. 26 yr, P < 0.0001). Preeclampsia occurred in 6.3 vs. 3.0% (P = 0.07). Aortic dissection occurred in one woman. Compared with the general population, the gestational age was shorter in children born by TS women (-6.4 d, P = 0.0067), and median birth weight was lower (-208 g, P = 0.0012), but sd scores for weight and length at birth were similar. The cesarean section rate was 35.6% in TS women and 11.8% in controls (P < 0.0001). There was no difference in birth defects in children of TS women as compared with controls. Conclusions: Obstetric outcomes in women with a TS karyotype were mostly favorable. Singletons of TS women had shorter gestational age, but similar size at birth, adjusted for gestational age and sex. Birth defects did not differ between TS and controls.
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| 2. |
- Becher, Paul G., et al.
(författare)
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Chemical signaling and insect attraction is a conserved trait in yeasts
- 2018
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; , s. 2962-2974
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Tidskriftsartikel (refereegranskat)abstract
- Yeast volatiles attract insects, which apparently is of mutual benefit, for both yeasts and insects. However, it is unknown whether biosynthesis of metabolites that attract insects is a basic and general trait, or if it is specific for yeasts that live in close association with insects. Our goal was to study chemical insect attractants produced by yeasts that span more than 250 million years of evolutionary history and vastly differ in their metabolism and lifestyle. We bioassayed attraction of the vinegar fly Drosophila melanogaster to odors of phylogenetically and ecologically distinct yeasts grown under controlled conditions. Baker's yeast Saccharomyces cerevisiae, the insect-associated species Candida californica, Pichia kluyveri and Metschnikowia andauensis, wine yeast Dekkera bruxellensis, milk yeast Kluyveromyces lactis, the vertebrate pathogens Candida albicans and Candida glabrata, and oleophilic Yarrowia lipolytica were screened for fly attraction in a wind tunnel. Yeast headspace was chemically analyzed, and co-occurrence of insect attractants in yeasts and flowering plants was investigated through a database search. In yeasts with known genomes, we investigated the occurrence of genes involved in the synthesis of key aroma compounds. Flies were attracted to all nine yeasts studied. The behavioral response to baker's yeast was independent of its growth stage. In addition to Drosophila, we tested the basal hexapod Folsomia candida (Collembola) in a Y-tube assay to the most ancient yeast, Y. lipolytica, which proved that early yeast signals also function on clades older than neopteran insects. Behavioral and chemical data and a search for selected genes of volatile metabolites underline that biosynthesis of chemical signals is found throughout the yeast clade and has been conserved during the evolution of yeast lifestyles. Literature and database reviews corroborate that yeast signals mediate mutualistic interactions between insects and yeasts. Moreover, volatiles emitted by yeasts are commonly found also in flowers and attract many insect species. The collective evidence suggests that the release of volatile signals by yeasts is a widespread and phylogenetically ancient trait, and that insect-yeast communication evolved prior to the emergence of flowering plants. Co-occurrence of the same attractant signals in yeast and flowers suggests that yeast-insect communication may have contributed to the evolution of insect-mediated pollination in flowers.
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| 3. |
- Becher, Paul, et al.
(författare)
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Yeast, not fruit volatiles mediate Drosophila melanogaster attraction, oviposition and development
- 2012
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Ingår i: Functional Ecology. - : Wiley. - 1365-2435 .- 0269-8463. ; 26:4, s. 822-828
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Tidskriftsartikel (refereegranskat)abstract
- 1.In nature, the fruit fly Drosophila melanogaster is attracted to fermenting fruit. Micro-organisms like Saccharomyces yeasts growing on fruit occupy a commonly overlooked trophic level between fruit and insects. Although the dietary quality of yeast is well established for D.melanogaster, the individual contribution of fruit and yeast on host finding and reproductive success has not been established. 2.Here, we show that baker's yeast Saccharomyces cerevisiae on its own is sufficient for fruit fly attraction, oviposition and larval development. In contrast, attraction and oviposition were significantly lower if non-fermented grape juice or growth media were used, and yeast-free grapes did not support larval development either. 3.Despite a strong preference for fermented substrates, moderate attraction to and oviposition on unfermented fruit might be adaptive in view of the fly's capacity to vector yeast. 4.Signals emitted by fruit were only of secondary importance because fermenting yeast without fruit induced the same fly behaviour as yeast fermenting on fruit. We identified a synthetic mimic of yeast odour, comprising ethanol, acetic acid, acetoin, 2-phenyl ethanol and 3-methyl-1-butanol, which was as attractive for the fly as fermenting grape juice or fermenting yeast minimal medium. 5.Yeast odours represent the critical signal to establish the flyfruityeast relationship. The traditional plantherbivore niche concept needs to be updated, to accommodate for the role of micro-organisms in insectplant interactions.
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| 4. |
- Chakraborty, Amrita, et al.
(författare)
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Yeast and fruit fly mutual niche construction and antagonism against mould
- 2022
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Ingår i: Functional Ecology. - : Wiley. - 0269-8463 .- 1365-2435. ; 36:7, s. 1639-1654
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Tidskriftsartikel (refereegranskat)abstract
- A goal in insect–microbe ecology is to understand the mechanisms regulating species associations and mutualistic interactions. The spotted wing drosophila Drosophila suzukii develops in ripening fruit, unlike other drosophilids that typically feed on overripe fruit, and is associated with the yeast Hanseniaspora uvarum. We hypothesized that D. suzukii and H. uvarum engage in niche construction leading to a mutualistic relation, facilitating the exploitation of fruit and berries as larval substrate. We show that H. uvarum proliferates on both ripe and on unripe raspberries, mediates attraction of D. suzukii larvae and adult flies, enhances egg-laying in mated females and is a sufficient food substrate to support larval development. Moreover, H. uvarum suppresses the antagonistic grey mould, Botrytis cinerea in collaboration with D. suzukii larvae, and produces less ethanol than baker's yeast. H. uvarum thus creates favourable conditions for D. suzukii larval development, which is susceptible to ethanol and grey mould. D. suzukii, on the other hand, vectors H. uvarum to suitable substrates such as raspberries, where larval feeding activity enhances growth of H. uvarum. Larval feeding also helps to suppress B. cinerea, which otherwise outcompetes H. uvarum on raspberry, in the absence of fly larvae. In conclusion, H. uvarum enhances D. suzukii larval development on unripe berries, and D. suzukii promotes H. uvarum dispersal and growth on berries. Yeast and fly modify their shared habitat in reciprocal niche construction and mutual interaction. Read the free Plain Language Summary for this article on the Journal blog.
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| 5. |
- Hagman, Arne, et al.
(författare)
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A Study on the Fundamental Mechanism and the Evolutionary Driving Forces behind Aerobic Fermentation in Yeast.
- 2015
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Baker's yeast Saccharomyces cerevisiae rapidly converts sugars to ethanol and carbon dioxide at both anaerobic and aerobic conditions. The later phenomenon is called Crabtree effect and has been described in two forms, long-term and short-term effect. We have previously studied under fully controlled aerobic conditions forty yeast species for their central carbon metabolism and the presence of long-term Crabtree effect. We have also studied ten steady-state yeast cultures, pulsed them with glucose, and followed the central carbon metabolism and the appearance of ethanol at dynamic conditions. In this paper we analyzed those wet laboratory data to elucidate possible mechanisms that determine the fate of glucose in different yeast species that cover approximately 250 million years of evolutionary history. We determine overflow metabolism to be the fundamental mechanism behind both long- and short-term Crabtree effect, which originated approximately 125-150 million years ago in the Saccharomyces lineage. The "invention" of overflow metabolism was the first step in the evolution of aerobic fermentation in yeast. It provides a general strategy to increase energy production rates, which we show is positively correlated to growth. The "invention" of overflow has also simultaneously enabled rapid glucose consumption in yeast, which is a trait that could have been selected for, to "starve" competitors in nature. We also show that glucose repression of respiration is confined mainly among S. cerevisiae and closely related species that diverged after the whole genome duplication event, less than 100 million years ago. Thus, glucose repression of respiration was apparently "invented" as a second step to further increase overflow and ethanol production, to inhibit growth of other microbes. The driving force behind the initial evolutionary steps was most likely competition with other microbes to faster consume and convert sugar into biomass, in niches that were semi-anaerobic.
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| 6. |
- Hagman, Arne, et al.
(författare)
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Analysis on yeast short-term Crabtree effect and its origin.
- 2014
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 281:21, s. 4805-4814
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Tidskriftsartikel (refereegranskat)abstract
- The short-term Crabtree effect is defined as the immediate appearance of aerobic alcoholic fermentation upon a pulse of excess sugar to sugar-limited yeast cultures. In this paper we characterized ten different yeast species, having a clearly defined phylogenetic relationship. Yeast species were cultivated under glucose-limited conditions, and upon a glucose pulse we studied their general carbon metabolism. We generated an extensive collection of data on glucose and oxygen consumption, and ethanol and carbon dioxide generation. We conclude that Pichia, Debaryomyces, Eremothecium and Kluyveromyces marxianus yeasts did not exhibit any significant ethanol formation, while Kluyveromyces lactis behaved as an intermediate yeast, and Lachancea, Torulaspora, Vanderwaltozyma and Saccharomyces yeasts exhibited rapid ethanol accumulation. Based on our previous data set covering over forty yeast species for the presence of the long-term Crabtree effect and our present data, we can speculate that the origin of the short-term effect may coincide with the origin of the long-term Crabtree effect in the Saccharomycetales lineage, taking place approximately 150 million years ago. This article is protected by copyright. All rights reserved.
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| 7. |
- Hagman, Arne
(författare)
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Evolution of Yeast Respiro-Fermentative Lifestyle and the Underlying Mechanisms Behind Aerobic Fermentation
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Under aerobic conditions, most yeasts such as Kluyveromyces lactis, prefer the respiratory pathway and some, such as Saccharomyces cerevisiae prefer less energy efficient fermentative pathway for their energy metabolism. These two metabolic strategies are also known as Crabtree negative and Crabtree positive respectively, and the evolution of the latter has lately been explained by the “make-accumulate-consume” life strategy. Scientists have for more than a century tried to elucidate the mechanism behind the physiology and the evolution of the peculiar respiro-fermentation trait. During the last decades, comparative genomics approaches have enabled the reconstruction of the evolutionary history of yeast, and several evolutionary events have been identified and postulated to have contributed to the development of the respiro-fermentative lifestyle in the Saccharomyces lineage. However, many of these inspiring studies have been verified with reference species only. Therefore, as parts of my thesis I conducted large-scale physiology studies of more than 40 yeast species and their central carbon metabolism under controlled conditions, in bioreactors. This was done in order to map the evolution of aerobic fermentation in yeast belonging to the Saccharomyces lineage that span over 200 million years of yeast evolution. This evolutionary blueprint, which most likely will be an invaluable information source of primary data for future in silico studies on the evolution of Crabtree effect, has already verified the importance of evolutionary events, such as promoter rewiring, chromatin relaxation, whole genome duplication, gene duplication and lateral gene-transfers. I further propose a mechanism that provides an explanation for the origin of the respiro-fermentative lifestyle in yeast, and how this was subsequently, through a multistep process developed into the Crabtree effect as we know it in the modern yeasts today, such as S. cerevisiae and its sister species.
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| 8. |
- Hagman, Arne, et al.
(författare)
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Yeast "make-accumulate-consume" life strategy evolved as a multi-step process that predates the whole genome duplication.
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:7
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Tidskriftsartikel (refereegranskat)abstract
- When fruits ripen, microbial communities start a fierce competition for the freely available fruit sugars. Three yeast lineages, including baker's yeast Saccharomyces cerevisiae, have independently developed the metabolic activity to convert simple sugars into ethanol even under fully aerobic conditions. This fermentation capacity, named Crabtree effect, reduces the cell-biomass production but provides in nature a tool to out-compete other microorganisms. Here, we analyzed over forty Saccharomycetaceae yeasts, covering over 200 million years of the evolutionary history, for their carbon metabolism. The experiments were done under strictly controlled and uniform conditions, which has not been done before. We show that the origin of Crabtree effect in Saccharomycetaceae predates the whole genome duplication and became a settled metabolic trait after the split of the S. cerevisiae and Kluyveromyces lineages, and coincided with the origin of modern fruit bearing plants. Our results suggest that ethanol fermentation evolved progressively, involving several successive molecular events that have gradually remodeled the yeast carbon metabolism. While some of the final evolutionary events, like gene duplications of glucose transporters and glycolytic enzymes, have been deduced, the earliest molecular events initiating Crabtree effect are still to be determined.
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| 9. |
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| 10. |
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| 11. |
- Hagman, Lars Arne, et al.
(författare)
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The use and implementation of CAD in the Swedish furniture industry
- 2006
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Ingår i: <em> </em>Forest Products Society 58<sup>th</sup> Annual Meeting, Bangkok, Thailand, 2004. ; , s. 73-81
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Konferensbidrag (refereegranskat)abstract
- This paper reports the results of and conclusions drawn from a questionnaire survey concerning the use and implementation of computer-aided design (CAD) in the Swedish furniture industry. The main question areas were how far the Swedish furniture industry has progressed in the use of CAD in product development, and how implementation has been performed. It was regarded as important to find out what impacts implementation has on the usage of CAD and whether companies in the furniture industry think the use of CAD could improve their product development. More than half of all product-developing companies in the Swedish furniture industry are using CAD today, and an increasing number of companies are implementing it. The furniture industry has come rather far in the use of CAD, but it could be better at implementing the systems in a proper manner. This could be related to companies often not planning their implementation; accordingly, they do not examine issues like organizational needs and goals, what the tool might be used for, and the resources required. The study found that the following factors are involved in successful implementation: management support, realistic budgeting, selection of system, and effective, company-specific training. Most CAD users are satisfied with their system and think that it fulfills their needs. Many of the difficulties referred to by respondents can be related to the implementation phase, and they could be avoided. In general, the furniture industry considers that CAD improves their product development work.
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| 12. |
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| 13. |
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| 14. |
- Johansson, Jan, et al.
(författare)
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Predicting moisture content and density distribution of Scots pine by microwave scanning of sawn timber
- 2003
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Ingår i: Journal of Wood Science. - : Springer Science and Business Media LLC. - 1435-0211 .- 1611-4663. ; 49:4, s. 312-316
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Tidskriftsartikel (refereegranskat)abstract
- This study was carried out to investigate the possibility of calibrating a prediction model for the moisture content and density distribution of Scots pine (Pinus sylvestris) using microwave sensors. The material was initially of green moisture content and was thereafter dried in several steps to zero moisture content. At each step, all the pieces were weighed, scanned with a microwave sensor (Satimo 9,4 GHz), and computed tomography (CT)-scanned with a medical CT scanner (Siemens Somatom AR.T.). The output variables from the microwave sensor were used as predictors, and CT images that correlated with known moisture content were used as response variables. Multivariate models to predict average moisture content and density were calibrated using the partial least squares (PLS) regression. The models for average moisture content and density were applied at the pixel level, and the distribution was visualized. The results show that it is possible to predict both moisture content distribution and density distribution with high accuracy using microwave sensors.
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| 15. |
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| 16. |
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| 17. |
- Rozpedowska, Elzbieta, et al.
(författare)
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Candida albicans- a pre-whole genome duplication yeast is predominantly aerobic and a poor ethanol producer.
- 2011
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Ingår i: FEMS Yeast Research. - : Oxford University Press (OUP). - 1567-1364 .- 1567-1356. ; 11:3, s. 285-291
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Tidskriftsartikel (refereegranskat)abstract
- Yeast species belonging to the lineage that underwent the whole genome duplication (WGD), and including Saccharomyces cerevisiae, can grow under anaerobiosis and accumulate ethanol in the presence of glucose and oxygen. The pre-WGD yeasts, which branched from the S. cerevisiae lineage just prior to the WGD event, including Kluyveromyces lactis, are more dependent on oxygen and do not accumulate large amounts of ethanol in the presence of excess oxygen. Yeasts that belong to the so-called 'lower branches' of the yeast phylogenetic tree and diverged from S. cerevisiae more than 200 million years ago, have so far not been thoroughly investigated for their physiology and carbon metabolism. We have hereby studied several isolates of Candida albicans and Debaryomyces hansenii for their dependence on oxygen. C. albicans grew very poorly at oxygen concentration below 1 p.p.m. and D. hansenii could not grow at all. In aerobic batch cultivations C. albicans exhibited a predominately aerobic metabolism, accumulating only small amounts of ethanol (0.01-0.09 g g(-1) glucose). Apparently, C. albicans and several other pre-WGD yeasts still exhibit the original traits of the yeast progenitor: poor accumulation of ethanol under aerobic conditions and strong dependence on the presence of oxygen.
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| 18. |
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| 19. |
- Witzgall, Peter, et al.
(författare)
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"This is not an Apple"-Yeast Mutualism in Codling Moth
- 2012
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Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 1573-1561 .- 0098-0331. ; 38:8, s. 949-957
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Tidskriftsartikel (refereegranskat)abstract
- The larva of codling moth Cydia pomonella (Tortricidae, Lepidoptera) is known as the worm in the apple, mining the fruit for food. We here show that codling moth larvae are closely associated with yeasts of the genus Metschnikowia. Yeast is an essential part of the larval diet and further promotes larval survival by reducing the incidence of fungal infestations in the apple. Larval feeding, on the other hand, enables yeast proliferation on unripe fruit. Chemical, physiological and behavioral analyses demonstrate that codling moth senses and responds to yeast aroma. Female moths are attracted to fermenting yeast and lay more eggs on yeast-inoculated than on yeast-free apples. An olfactory response to yeast volatiles strongly suggests a contributing role of yeast in host finding, in addition to plant volatiles. Codling moth is a widely studied insect of worldwide economic importance, and it is noteworthy that its association with yeasts has gone unnoticed. Tripartite relationships between moths, plants, and microorganisms may, accordingly, be more widespread than previously thought. It, therefore, is important to study the impact of microorganisms on host plant ecology and their contribution to the signals that mediate host plant finding and recognition. A better comprehension of host volatile signatures also will facilitate further development of semiochemicals for sustainable insect control.
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