| 1. |
- Forslund, Ola, et al.
(author)
-
Cutaneous human papillomaviruses found in sun-exposed skin: Beta-papillomavirus species 2 predominates in squamous cell carcinoma
- 2007
-
In: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 1537-6613 .- 0022-1899. ; 196, s. 876-83
-
Journal article (peer-reviewed)abstract
- Background. A spectrum of cutaneous human papillomaviruses (HPVs) is detectable in nonmelanoma skin cancers, as well as in healthy skin, but the significance that the presence of these types of HPV DNA has for the pathogenesis of skin cancer remains unclear. Methods. We studied 349 nonimmunosuppressed patients with skin lesions (82 with squamous cell carcinomas, 126 with basal cell carcinomas, 49 with actinic keratoses, and 92 with benign lesions). After superficial skin had been removed by tape, paired biopsy samples-from the lesion and from healthy skin from the same patient-were tested for HPV DNA. Risk factors for HPV DNA were analyzed in multivariate models. Results. Overall, 12% of healthy skin samples were positive for HPV DNA, compared with 26% of benign lesions, 22% of actinic keratoses, 18% of basal cell carcinomas, and 26% of squamous cell carcinomas. HPV DNA was associated with sites extensively exposed to the sun, both for the lesions (odds ratio [OR], 4.45 [95% confidence interval {CI}, 2.44-8.111) and for the healthy skin samples (OR, 3.65 [95% CI 1.79-7.44]). HPV types of Beta-papillomavirus species 2 predominate in squamous cell carcinomas (OR, 4.40 [95% CI, 1.92-10.06]), whereas HPV types of Beta-papillomavirus species 1 are primarily found in benign lesions (OR, 3.47 [95% CI, 1.72-6.99]). Conclusions. Cutaneous HPV types are primarily detected at sites extensively exposed to the sun. HPV types of Beta-papillomavirus species 2, but not of species 1, are associated with squamous cell carcinoma.
|
|
| 2. |
- Johansson, Jarkko, et al.
(author)
-
Biphasic patterns of age-related differences in dopamine D1 receptors across the adult lifespan
- 2023
-
In: Cell Reports. - 2211-1247. ; 42:9
-
Journal article (peer-reviewed)abstract
- Age-related alterations in D1-like dopamine receptor (D1DR) have distinct implications for human cognition and behavior during development and aging, but the timing of these periods remains undefined. Enabled by a large sample of in vivo assessments (n = 180, age 20 to 80 years of age, 50% female), we discover that age-related D1DR differences pivot at approximately 40 years of age in several brain regions. Focusing on the most age-sensitive dopamine-rich region, we observe opposing pre- and post-forties interrelations among caudate D1DR, cortico-striatal functional connectivity, and memory. Finally, particularly caudate D1DR differences in midlife and beyond, but not in early adulthood, associate with manifestation of white matter lesions. The present results support a model by which excessive dopamine modulation in early adulthood and insufficient modulation in aging are deleterious to brain function and cognition, thus challenging a prevailing view of monotonic D1DR function across the adult lifespan.
|
|
| 3. |
- Johansson, Otilia, 1979-
(author)
-
Epiphytic lichen responses to nitrogen deposition
- 2011
-
Doctoral thesis (other academic/artistic)abstract
- Nitrogen (N) deposition has increased globally over the last 150 years and further increase is predicted for the future. Nitrogen is an important nutrient for lichens, involved in many processes in both photobiont and mycobiont. However, N can be a stressor, causing many lichens and lichen communities to disappear with increased deposition. The objective of this thesis was to investigate the response of epiphytic lichens to increased N load. This was done by simulating an increased N deposition to lichens in a boreal forest with low background N, including both short term studies with transplanted lichens and long term studies of naturally established lichens. Alectoria sarmentosa was used as a model species for a N-sensitive lichens and Platismatia glauca as a relatively more N-tolerant lichen. Nitrogen deposition was simulated by daily spraying during the growing season with water and isotopically labeled ammonium nitrate (NH4NO3). In Paper I, I found that when N is supplied in realistic doses (equivalent to deposition of 0.6, 6, 12.5, 25 and 50 kg N ha-1), there were no significant differences in uptake of NO3- or NH4+ in either of the lichen species. The results in Paper II indicate that A. samentosa may be limited by phosphorous (P) and not N limited as expected. That study highlights the importance of P, when studying the effects of N deposition, since P can both mitigate and intensify the negative effects of N on epiphytic lichens. Paper III shows that four years of simulated N deposition caused an alteration of the epiphytic lichen community, since A. sarmentosa decreased in the highest N loads (25 and 50 kg ha-1 year-1), Bryoria spp. decreased to 12.5 kg N and higher loads and Hypogymnia physodes decreased over time for all treatments except in 12.5 kg ha-1, where it only decreased during the first treatment year and then increased after 2007. The abundance of Platismatia glauca increased over time, independent of treatment. As hypothesized, responses to the treatments differed among species, reflecting their different N optima. In paper IV, the effects of N on carbon-based secondary compounds were studied. None of the studied species (P. glauca, A. sarmentosa, Lobaria scrobiculata and Xanthoria aureola) reduced their concentration of secondary compounds during the experimental period, but in P. glauca the concentration of all compounds were significantly lower in N treated thalli compared with control thalli. The results are consistent with a high degree of constitutive defence in three of the four studied lichens, and we conclude that all four studied lichens seem to have a robust chemical defence system despite considerable manipulation of the environmental conditions. However, we don't know if these lichens are able to keep up the high protection level over longer periods comprising a number of years when more new tissue is formed. In conclusion, long term experiments are necessary to understand lichen response to environmental changes.
|
|
| 4. |
- Johansson, Otilia, et al.
(author)
-
Responses of epiphytic lichens to an experimental whole-tree nitrogen-deposition gradient
- 2010
-
In: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 188:4, s. 1075-1084
-
Journal article (peer-reviewed)abstract
- • Here, we examined the responses of the epiphytic lichens Alectoria sarmentosa and Platismatia glauca to increased atmospheric nitrogen (N) deposition in an old-growth boreal spruce forest, to assess the sensitivity of these species to N and define their critical N load. • Nitrogen deposition was simulated by irrigating 15 trees over a 3 yr period with water and isotopically labeled NH(4) NO(3) , providing N loads ranging from ambient to 50 kg N ha(-1) yr(-1) . • Thallus N concentration increased in both species with increasing N load, and uptake rates of both NH(4) (+) and NO(3) (-) were similar. Photobiont concentration increased linearly with increased N in both species, saturating in A. sarmentosa in the third year at the highest N loads (25 and 50 kg ha(-1 ) yr(-1) ). The simulated N deposition decreased the phosphorus (P) concentration in A. sarmentosa, and increased the N : P ratio in both species. • Significant responses in lichen chemistry were detected to inputs of 12.5 kg N ha(-1) yr(-1) or higher, suggesting that resources other than N limit lichens at higher N loads. However, the data also suggest that N saturation may be cumulative over time, even at low N.
|
|
| 5. |
- Maaroufi, Nadia, et al.
(author)
-
Anthropogenic nitrogen deposition enhances carbon sequestration in boreal soils
- 2015
-
In: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 21:8, s. 3169-3180
-
Journal article (peer-reviewed)abstract
- It is proposed that carbon (C) sequestration in response to reactive nitrogen (N-r) deposition in boreal forests accounts for a large portion of the terrestrial sink for anthropogenic CO2 emissions. While studies have helped clarify the magnitude by which N-r deposition enhances C sequestration by forest vegetation, there remains a paucity of long-term experimental studies evaluating how soil C pools respond. We conducted a long-term experiment, maintained since 1996, consisting of three N addition levels (0, 12.5, and 50kgNha(-1)yr(-1)) in the boreal zone of northern Sweden to understand how atmospheric N-r deposition affects soil C accumulation, soil microbial communities, and soil respiration. We hypothesized that soil C sequestration will increase, and soil microbial biomass and soil respiration will decrease, with disproportionately large changes expected compared to low levels of N addition. Our data showed that the low N addition treatment caused a non-significant increase in the organic horizon C pool of similar to 15% and a significant increase of similar to 30% in response to the high N treatment relative to the control. The relationship between C sequestration and N addition in the organic horizon was linear, with a slope of 10kgCkg(-1)N. We also found a concomitant decrease in total microbial and fungal biomasses and a similar to 11% reduction in soil respiration in response to the high N treatment. Our data complement previous data from the same study system describing aboveground C sequestration, indicating a total ecosystem sequestration rate of 26kgCkg(-1)N. These estimates are far lower than suggested by some previous modeling studies, and thus will help improve and validate current modeling efforts aimed at separating the effect of multiple global change factors on the C balance of the boreal region.
|
|
| 6. |
- Maaroufi, Nadia, et al.
(author)
-
Anthropogenic nitrogen enrichment enhances soil carbon accumulation by impacting saprotrophs rather than ectomycorrhizal fungal activity
- 2019
-
In: Global Change Biology. - : John Wiley & Sons. - 1354-1013 .- 1365-2486. ; 25:9, s. 2900-2914
-
Journal article (peer-reviewed)abstract
- There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal forest soils. However, it is unclear how free-living saprotrophs (bacteria and fungi, SAP) and ectomycorrhizal (EM) fungi responses to N addition impact soil C dynamics. Our aim was to investigate how SAP and EM communities are impacted by N enrichment and to estimate whether these changes influence decay of litter and humus. We conducted a long-term experiment in northern Sweden, maintained since 2004, consisting of ambient, low N additions (0, 3, 6, and 12 kg N ha(-1) year(-1)) simulating current N deposition rates in the boreal region, as well as a high N addition (50 kg N ha(-1) year(-1)). Our data showed that long-term N enrichment impeded mass loss of litter, but not of humus, and only in response to the highest N addition treatment. Furthermore, our data showed that EM fungi reduced the mass of N and P in both substrates during the incubation period compared to when only SAP organisms were present. Low N additions had no effect on microbial community structure, while the high N addition decreased fungal and bacterial biomasses and altered EM fungi and SAP community composition. Actinomycetes were the only bacterial SAP to show increased biomass in response to the highest N addition. These results provide a mechanistic understanding of how anthropogenic N enrichment can influence soil C accumulation rates and suggest that current N deposition rates in the boreal region (<= 12 kg N ha(-1) year(-1)) are likely to have a minor impact on the soil microbial community and the decomposition of humus and litter.
|
|
| 7. |
- Maaroufi, Nadia, et al.
(author)
-
Chronic Nitrogen Deposition Has a Minor Effect on the Quantity and Quality of Aboveground Litter in a Boreal Forest
- 2016
-
In: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:8
-
Journal article (peer-reviewed)abstract
- There is evidence that anthropogenic nitrogen (N) deposition enhances carbon (C) sequestration in boreal soils. However, key underlying mechanisms explaining this increase have not been resolved. Two potentially important mechanisms are that aboveground litter production increases, or that litter quality changes in response to N enrichment. As such, our aim was to quantify whether simulated chronic N deposition caused changes in aboveground litter production or quality in a boreal forest. We conducted a long-term (17 years) stand-scale (0.1 ha) forest experiment, consisting of three N addition levels (0, 12.5, and 50 kg N ha(-1) yr(-1)) in northern Sweden, where background N deposition rates are very low. We measured the annual quantity of litter produced for 8 different litter categories, as well as their concentrations of C, N, phosphorus (P), lignin, cellulose and hemi-cellulose. Our results indicate that mosses were the only major litter component showing significant quantitative and qualitative alterations in response to the N additions, indicative of their ability to intercept a substantial portion of the N added. These effects were, however, offset by the other litter fractions where we found no changes in the total litter fluxes, or individual chemical constituents when all litter categories were summed. This study indicates that the current annual litter fluxes cannot explain the increase in soil C that has occurred in our study system in response to simulated chronic N application. These results suggest that other mechanisms are likely to explain the increased soil C accumulation rate we have observed, such as changes in soil microbial activity, or potentially transient changes in aboveground litter inputs that were no longer present at the time of our study.
|
|
| 8. |
- Maaroufi, Nadia, et al.
(author)
-
Nitrogen enrichment impacts on boreal litter decomposition are driven by changes in soil microbiota rather than litter quality
- 2017
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
-
Journal article (peer-reviewed)abstract
- In nitrogen (N) limited boreal forests, N enrichment can impact litter decomposition by affecting litter quality and by changing the soil environment where litter decomposes. We investigated the importance of litter quality and soil factors on litter decomposition using a 2-year reciprocal transplant experiment for Picea abies needle litter, derived from plots subjected to 17 years of N addition, including control, low and high N treatments (ambient, 12.5 and 50 kg N ha(-1) yr(-1), respectively). Our data show that changes in soil factors were the main pathway through which N impacted litter decomposition, with rates reduced by approximate to 15% when placed in high N relative to control plots, regardless of litter origin. Litter decomposition was correlated to soil microbiota, with Picea abies litter decomposition positively correlated with gram negative and fungal functional groups. Our results suggest that previous findings of increase soil C accumulation in response to N deposition is likely to occur as a result of changes in soil microbiota rather than altered litter quality.
|
|
| 9. |
- Maaroufi, Nadia, et al.
(author)
-
Nutrient optimization of tree growth alters structure and function of boreal soil food webs
- 2018
-
In: Forest Ecology and Management. - Amsterdam : Elsevier. - 0378-1127 .- 1872-7042. ; 428, s. 46-56
-
Journal article (peer-reviewed)abstract
- Nutrient optimization has been proposed as a way to increase boreal forest production, and involves chronic additions of liquid fertilizer with amounts of micro- and macro-nutrients adjusted annually to match tree nutritional requirements. We used a short-term (maintained since 2007) and a long-term (maintained since 1987) fertilization experiment in northern Sweden, in order to understand nutrient optimization effects on soil microbiota and mesofauna, and to explore the relationships between plant litter and microbial elemental stoichiometry. Soil microbes, soil fauna, and aboveground litter were collected from the control plots, and short- and long-term nutrient optimization plots. Correlation analyses revealed no relationships between microbial biomass and litter nutrient ratios. Litter C:N, C:P and N:P ratios declined in response to both optimization treatments; while only microbial C:P ratios declined in response to long-term nutrient optimization. Further, we found that both short- and long-term optimization treatments decreased total microbial, fungal, and bacterial PLFA biomass and shifted the microbial community structure towards a lower fungi:bacterial ratio. In contrast, abundances of most fungal- and bacterial-feeding soil biota were little affected by the nutrient optimization treatments. However, abundance of hemi-edaphic Collembola declined in response to the long-term nutrient optimization treatment. The relative abundances (%) of fungal-feeding and plant-feeding nematodes, respectively, declined and increased in response to both short-term and long-term treatments; bacterial-feeding nematodes increased relative to fungal feeders. Overall, our results demonstrate that long-term nutrient optimization aiming to increase forest production decreases litter C:N, C:P and N:P ratios, microbial C:P ratios and fungal biomass, whereas higher trophic levels are less affected. © 2018 Elsevier B.V.
|
|
| 10. |
- Mayes, Maureen D, et al.
(author)
-
Immunochip analysis identifies multiple susceptibility Loci for systemic sclerosis.
- 2014
-
In: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297 .- 1537-6605. ; 94:1, s. 47-61
-
Journal article (peer-reviewed)abstract
- In this study, 1,833 systemic sclerosis (SSc) cases and 3,466 controls were genotyped with the Immunochip array. Classical alleles, amino acid residues, and SNPs across the human leukocyte antigen (HLA) region were imputed and tested. These analyses resulted in a model composed of six polymorphic amino acid positions and seven SNPs that explained the observed significant associations in the region. In addition, a replication step comprising 4,017 SSc cases and 5,935 controls was carried out for several selected non-HLA variants, reaching a total of 5,850 cases and 9,401 controls of European ancestry. Following this strategy, we identified and validated three SSc risk loci, including DNASE1L3 at 3p14, the SCHIP1-IL12A locus at 3q25, and ATG5 at 6q21, as well as a suggested association of the TREH-DDX6 locus at 11q23. The associations of several previously reported SSc risk loci were validated and further refined, and the observed peak of association in PXK was related to DNASE1L3. Our study has increased the number of known genetic associations with SSc, provided further insight into the pleiotropic effects of shared autoimmune risk factors, and highlighted the power of dense mapping for detecting previously overlooked susceptibility loci.
|
|
