| 1. |
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| 2. |
- Dincbas-Renqvist, Vildan, et al.
(författare)
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Thermodynamics of folding, stabilization, and binding in an engineered protein--protein complex.
- 2004
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 126:36, s. 11220-30
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed the thermodynamics of a complex protein-protein binding interaction using the (engineered) Z(SPA)(-)(1) affibody and it's Z domain binding partner as a model. Free Z(SPA)(-)(1) exists in an equilibrium between a molten-globule-like (MG) state and a completely unfolded state, wheras a well-ordered structure is observed in the Z:Z(SPA)(-)(1) complex. The thermodynamics of the MG state unfolding equilibrium can be separated from the thermodynamics of binding and stabilization by combined analysis of isothermal titration calorimetry data and a separate van't Hoff analysis of thermal unfolding. We find that (i) the unfolding equilibrium of free Z(SPA)(-)(1) has only a small influence on effective binding affinity, that (ii) the Z:Z(SPA)(-)(1) interface is inconspicuous and structure-based energetics calculations suggest that it should be capable of supporting strong binding, but that (iii) the conformational stabilization of the MG state to a well-ordered structure in the Z:Z(SPA)(-)(1) complex is associated with a large change in conformational entropy that opposes binding.
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| 3. |
- Jorgensen, Jesper Roland, et al.
(författare)
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Cometin is a novel neurotrophic factor that promotes neurite outgrowth and neuroblast migration in vitro and supports survival of spiral ganglion neurons in vivo
- 2012
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 233:1, s. 172-181
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Tidskriftsartikel (refereegranskat)abstract
- Neurotrophic factors are secreted proteins responsible for migration, growth and survival of neurons during development, and for maintenance and plasticity of adult neurons. Here we present a novel secreted protein named Cometin which together with Meteorin defines a new evolutionary conserved protein family. During early mouse development, Cometin is found exclusively in the floor plate and from E13.5 also in dorsal root ganglions and inner ear but apparently not in the adult nervous system. In vitro, Cometin promotes neurite outgrowth from dorsal root ganglion cells which can be blocked by inhibition of the Janus or MEK kinases. In this assay, additive effects of Cometin and Meteorin are observed indicating separate receptors. Furthermore, Cometin supports migration of neuroblasts from subventricular zone explants to the same extend as stromal cell derived factor la. Given the neurotrophic properties in vitro, combined with the restricted inner ear expression during development, we further investigated Cometin in relation to deafness. In neomycin deafened guinea pigs, two weeks intracochlear infusion of recombinant Cometin supports spiral ganglion neuron survival and function. In contrast to the control group receiving artificial perilymph, Cometin treated animals retain normal electrically-evoked brainstem response which is maintained several weeks after treatment cessation. Neuroprotection is also evident from stereological analysis of the spiral ganglion. Altogether, these studies show that Cometin is a potent new neurotrophic factor with therapeutic potential. (C) 2011 Elsevier Inc. All rights reserved.
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| 4. |
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| 5. |
- Lendel, Christofer, et al.
(författare)
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Biophysical characterization of Z(SPA-1)--a phage-display selected binder to protein A.
- 2004
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Ingår i: Protein science : a publication of the Protein Society. - : Wiley. - 0961-8368 .- 1469-896X. ; 13:8, s. 2078-88
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Tidskriftsartikel (refereegranskat)abstract
- Affibodies are a novel class of binding proteins selected from phagemid libraries of the Z domain from staphylococcal protein A. The Z(SPA-1) affibody was selected as a binder to protein A, and it binds the parental Z domain with micromolar affinity. In earlier work we determined the structure of the Z:Z(SPA-1) complex and noted that Z(SPA-1) in the free state exhibits several properties characteristic of a molten globule. Here we present a more detailed biophysical investigation of Z(SPA-1) and four Z(SPA-1) mutants with the objective to understand these properties. The characterization includes thermal and chemical denaturation profiles, ANS binding assays, size exclusion chromatography, isothermal titration calorimetry, and an investigation of structure and dynamics by NMR. The NMR characterization of Z(SPA-1) was facilitated by the finding that trimethylamine N-oxide (TMAO) stabilizes the molten globule conformation in favor of the fully unfolded state. All data taken together lead us to conclude the following: (1) The topology of the molten globule conformation of free Z(SPA-1) is similar to that of the fully folded structure in the Z-bound state; (2) the extensive mutations in helices 1 and 2 destabilize these without affecting the intrinsic stability of helix 3; (3) stabilization and reduced aggregation can be achieved by replacing mutated residues in Z(SPA-1) with the corresponding wild-type Z residues. This stabilization is better correlated to changes in helix propensity than to an expected increase in polar versus nonpolar surface area of the fully folded state.
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| 6. |
- Lindahl, Göran, et al.
(författare)
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Bergslagen : Arbetsplatser och bostäder under hundra år
- 1983
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Rapport (populärvet., debatt m.m.)abstract
- Denna skrift utgör resultatet av Arkitekturskolans studier läsåret 1978-79. Att redigera manuskripten visade sig arbetskrävande och har också dragit ut på tiden. Att vissa av de uppgifter som lämnas inte är helt aktuella spelar ändå inte så stor roll - tyngdpunkten i framställningen ligger på det historiska materialet och de långa tidsperspektiven.Arbetet inleds med en demografisk översikt över ett brett bälte tvärs över Mellansverige från Värmland till Upplandskusten. Där antyds utvecklingens huvudriktning både i Bergslagens gamla kärnområden och i yttre zoner av delvis annan karaktär. Därefter följer åtta från varandra fristående kapitel som dock alla har ett gemensamt mål, att granska och analysera bebyggelseu.tvecklingen inom ett tydligt avgränsat område. Konkretion och åskådlighet har eftersträvats - därför har också stor möda nedlagts på bildmaterialet i form av kartor, ritningar och foton. Valet av undersökningsobjekt har gjorts av författarna själva, som också utformat sina avsnitt självständigt.
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| 7. |
- Peña, Carlos, et al.
(författare)
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Higher level phylogeny of Satyrinae butterflies (Lepidoptera: Nymphalidae) based on DNA sequence data
- 2006
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Ingår i: Molecular Phylogenetics and Evolution. - : Elsevier BV. - 1055-7903 .- 1095-9513. ; 40:1, s. 29-49
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Tidskriftsartikel (refereegranskat)abstract
- We have inferred the first empirically supported hypothesis of relationships for the cosmopolitan butterfly subfamily Satyrinae. We used 3090 base pairs of DNA from the mitochondrial gene COI and the nuclear genes EF-1alpha and wingless for 165 Satyrinae taxa representing 4 tribes and 15 subtribes, and 26 outgroups, in order to test the monophyly of the subfamily and elucidate phylogenetic relationships of its major lineages. In a combined analysis, the three gene regions supported an almost fully resolved topology, which recovered Satyrinae as polyphyletic, and revealed that the current classification of suprageneric taxa within the subfamily is comprised almost completely of unnatural assemblages. The most noteworthy findings are that Manataria is closely related to Melanitini; Palaeonympha belongs to Euptychiina; Oressinoma, Orsotriaena and Coenonympha group with the Hypocystina; Miller's (1968). Parargina is polyphyletic and its components group with multiple distantly related lineages; and the subtribes Elymniina and Zetherina fall outside the Satyrinae. The three gene regions used in a combined analysis prove to be very effective in resolving relationships of Satyrinae at the subtribal and tribal levels. Further sampling of the taxa closely related to Satyrinae, as well as more extensive sampling of genera within the tribes and subtribes for this group will be critical to test the monophyly of the subfamily and establish a stronger basis for future biogeographical and evolutionary studies.
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| 8. |
- Schill, Fredrika, et al.
(författare)
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Pituitary Metastases : A Nationwide Study on Current Characteristics With Special Reference to Breast Cancer
- 2019
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 104:8, s. 3379-3388
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the contemporary presentation of pituitary metastases. Patients: Thirty-eight patients diagnosed with pituitary metastases from 1996 to 2018 in Sweden.Methods: Pituitary metastases were confirmed by histopathology (n = 27) or considered highly likely according to radiological findings, including rapid tumor progression (n = 11). Medical records were reviewed and cellar images reexamined centrally.Results: Breast and lung cancers were the most common primary tumors, in 45% and 21% of patients, respectively. Sixty-seven percent of breast cancers overexpressed human epidermal growth factor receptor 2 (HER2); 53% of pituitary metastases from breast cancers appeared >= 10 years after diagnosis of the primary tumor. At presentation, 71% appeared to have ACTH deficiency, 65% had TSH deficiency, and 26% had diabetes insipidus. Fatigue, nausea/vomiting, loss of appetite, weight loss, myalgia, and/or arthralgia were reported in 47% of patients with morning cortisol <100 nmol/L vs 23% with cortisol >= 200 nmol/L. Sixteen patients had visual field defects, and eight had diplopia. Intrasellar and suprasellar tumor growth was the most frequent finding. Initially, a pituitary adenoma was considered the etiology in 18% of patients. Radiotherapy, pituitary surgery, and chemotherapy were used in 68%, 68%, and 11% of patients, respectively. One and 2 years after diagnosis of pituitary metastases, 50% and 26% of patients were alive.Conclusion: Pituitary metastases may be mistaken for pituitary adenomas and can appear late, especially in breast cancer. Breast cancers overexpressing HER2 seem prone to metastasize to the pituitary. Hypocortisolism may be misdiagnosed as cancer-related malaise. An increased awareness of pituitary metastases and undiagnosed pituitary failure can improve management in these patients.
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| 9. |
- Schutz, Patrick, et al.
(författare)
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Crystal structure of human RNA helicase A (DHX9 : structural basis for unselective nucleotide base binding in a DEAD-box variant protein
- 2010
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Ingår i: Journal of Molecular Biology. - : Elsevier. - 0022-2836 .- 1089-8638. ; 400:4, s. 768-782
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Tidskriftsartikel (refereegranskat)abstract
- RNA helicases of the DExD/H-box superfamily are critically involved in all RNA-related processes. No crystal structures of human DExH-box domains had been determined previously, and their structures were difficult to predict owing to the low level of homology among DExH-motif-containing proteins from diverse species. Here we present the crystal structures of the conserved domain 1 of the DEIH-motif-containing helicase DHX9 and of the DEAD-box helicase DDX20. Both contain a RecA-like core, but DHX9 differs from DEAD-box proteins in the arrangement of secondary structural elements and is more similar to viral helicases such as NS3. The N-terminus of the DHX9 core contains two long alpha-helices that reside on the surface of the core without contributing to nucleotide binding. The RNA-polymerase-II-interacting minimal transactivation domain sequence forms an extended loop structure that resides in a hydrophobic groove on the surface of the DEIH domain. DHX9 lacks base-selective contacts and forms an unspecific but important stacking interaction with the base of the bound nucleotide, and our biochemical analysis confirms that the protein can hydrolyze ATP, guanosine 5'-triphosphate, cytidine 5'-triphosphate, and uridine 5'-triphosphate. Together, these findings allow the localization of functional motifs within the three-dimensional structure of a human DEIH helicase and show how these enzymes can bind nucleotide with high affinity in the absence of a Q-motif.
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| 10. |
- Trotter, Dinko E. Gonzalez, et al.
(författare)
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In Vivo Imaging of the Programmed Death Ligand 1 by F-18 PET
- 2017
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Ingår i: Journal of Nuclear Medicine. - : Society of Nuclear Medicine. - 0161-5505 .- 1535-5667 .- 2159-662X. ; 58:11, s. 1852-1857
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Tidskriftsartikel (refereegranskat)abstract
- Programmed death ligand 1 (PD-L1) is an immune regulatory ligand that binds to the T-cell immune check point programmed death 1. Tumor expression of PD-L1 is correlated with immune suppression and poor prognosis. It is also correlated with therapeutic efficacy of programmed death 1 and PD-L1 inhibitors. In vivo imaging may enable real-time follow-up of changing PD-L1 expression and heterogeneity evaluation of PD-L1 expression across tumors in the same subject. We have radiolabeled the PD-L1-binding Affibody molecule NOTA-Z(PD-L1_1) with F-18 and evaluated its in vitro and in vivo binding affinity, targeting, and specificity. Methods: The affinity of the PD-L1-binding Affibody ligand Z(PD-L1_1) was evaluated by surface plasmon resonance. Labeling was accomplished by maleimide coupling of NOTA to a unique cysteine residue and chelation of F-18-AlF. In vivo studies were performed in PD-L1-positive, PD-L1-negative, and mixed tumor-bearing severe combined immunodeficiency mice. Tracer was injected via the tail vein, and dynamic PET scans were acquired for 90 min, followed by gamma-counting biodistribution. Immunohistochemical staining with an antibody specific for anti-PD-L1 (22C3) was used to evaluate the tumor distribution of PD-L1. Immunohistochemistry results were then compared with ex vivo autoradiographic images obtained from adjacent tissue sections. Results: NOTA-Z(PD-L1_1) was labeled, with a radiochemical yield of 15.1% +/- 5.6%, radiochemical purity of 96.7% +/- 2.0%, and specific activity of 14.6 +/- 6.5 GBq/mu mol. Surface plasmon resonance showed a NOTA-conjugated ligand binding affinity of 1 nM. PET imaging demonstrated rapid uptake of tracer in the PD-L1-positive tumor, whereas the PD-L1-negative control tumor showed little tracer retention. Tracer clearance from most organs and blood was quick, with biodistribution showing prominent kidney retention, low liver uptake, and a significant difference between PD-L1-positive (percentage injected dose per gram [%ID/g] = 2.56 +/- 0.33) and -negative (% ID/g = 0.32 +/- 0.05) tumors (P = 0.0006). Ex vivo autoradiography showed excellent spatial correlation with immunohistochemistry in mixed tumors. Conclusion: Our results show that Affibody ligands can be effective at targeting tumor PD-L1 in vivo, with good specificity and rapid clearance. Future studies will explore methods to reduce kidney activity retention and further increase tumor uptake.
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| 11. |
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| 12. |
- Wahlberg, Anna Carin, et al.
(författare)
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Bases for assessments made by telephone advice nurses
- 2005
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Ingår i: Journal of Telemedicine and Telecare. - 1357-633X .- 1758-1109. ; 11:8, s. 403-407
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Tidskriftsartikel (refereegranskat)abstract
- Telephone advice nursing includes triage, advice, referral, information and coordination. The aim of the study was to explore what telephone nurses base their assessments on. We conducted 14 interviews with seven telephone nurses at a health-care call centre in Sweden. Two authentic calls per nurse were used in stimulated recall interviews, where the nurses commented on the basis for their assessments. A qualitative manifest content analysis was employed. Three major categories emerged in the analysis: care-seeker, e.g. 'symptomatic sounds', nurse, e.g. 'nurse's own experience', and organization, e.g. 'health-care accessibility'. The findings show that the telephone advice nurses' bases for assessments appear to be very broad. They include both verbally and non-verbally communicated information, and care-seeker-, nurse- and certain organization-related factors influence the assessments. We found that an individualistic view of the care-seeker seems to dominate the assessments in non-urgent calls to a health-care call centre.
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| 13. |
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| 14. |
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| 15. |
- Wahlberg, Elisabet, et al.
(författare)
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An affibody in complex with a target protein: Structure and coupled folding.
- 2003
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 100:6, s. 3185-3190
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Tidskriftsartikel (refereegranskat)abstract
- Combinatorial protein engineering provides powerful means for functional selection of novel binding proteins. One class of engineered binding proteins, denoted affibodies, is based on the three-helix scaffold of the Z domain derived from staphylococcal protein A. The Z(SPA-1) affibody has been selected from a phage-displayed library as a binder to protein A. Z(SPA-1) also binds with micromolar affinity to its own ancestor, the Z domain. We have characterized the Z(SPA-1) affibody in its uncomplexed state and determined the solution structure of a Z:Z(SPA-1) protein-protein complex. Uncomplexed Z(SPA-1) behaves as an aggregation-prone molten globule, but folding occurs on binding, and the original (Z) three-helix bundle scaffold is fully formed in the complex. The structural basis for selection and strong binding is a large interaction interface with tight steric and polar/nonpolar complementarity that directly involves 10 of 13 mutated amino acid residues on Z(SPA-1). We also note similarities in how the surface of the Z domain responds by induced fit to binding of Z(SPA-1) and Ig Fc, respectively, suggesting that the Z(SPA-1) affibody is capable of mimicking the morphology of the natural binding partner for the Z domain.
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| 16. |
- Wahlberg, Elisabet, et al.
(författare)
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Conformational stabilization of an engineered binding protein.
- 2006
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 128:23, s. 7651-60
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed the thermodynamic basis for improvement of a binding protein by disulfide engineering. The Z(SPA)(-)(1) affibody binds to its Z domain binding partner with a dissociation constant K(d) = 1.6 microM, and previous analyses suggested that the moderate affinity is due to the conformational heterogeneity of free Z(SPA)(-)(1) rather than to a suboptimal binding interface. Studies of five stabilized Z(SPA)(-)(1) double cystein mutants show that it is possible to improve the affinity by an order of magnitude to K(d) = 130 nM, which is close to the range (20 to 70 nM) observed with natural Z domain binders, without altering the protein-protein interface obtained by phage display. Analysis of the binding thermodynamics reveals a balance between conformational entropy and desolvation entropy: the expected and favorable reduction of conformational entropy in the best-binding Z(SPA)(-)(1) mutant is completely compensated by an unfavorable loss of desolvation entropy. This is consistent with a restriction of possible conformations in the disulfide-containing mutant and a reduction of average water-exposed nonpolar surface area in the free state, resulting in a smaller conformational entropy penalty, but also a smaller change in surface area, for binding of mutant compared to wild-type Z(SPA)(-)(1). Instead, higher Z domain binding affinity in a group of eight Z(SPA)(-)(1) variants correlates with more favorable binding enthalpy and enthalpy-entropy compensation. These results suggest that protein-protein binding affinity can be improved by stabilizing conformations in which enthalpic effects can be fully explored.
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| 17. |
- Wahlberg, Elisabet, et al.
(författare)
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Identification of proteins that specifically recognize and bind protofibrillar aggregates of amyloid-β
- 2017
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Protofibrils of the 42 amino acids long amyloid-β peptide are transient pre-fibrillar intermediates in the process of peptide aggregation into amyloid plaques and are thought to play a critical role in the pathology of Alzheimer's disease. Hence, there is a need for research reagents and potential diagnostic reagents for detection and imaging of such aggregates. Here we describe an in vitro selection of Affibody molecules that bind to protofibrils of Aβ42cc, which is a stable engineered mimic of wild type Aβ42 protofibrils. Several binders were identified that bind Aβ42cc protofibrils with low nanomolar affinities, and which also recognize wild type Aβ42 protofibrils. Dimeric head-to-tail fusion proteins with subnanomolar binding affinities, and very slow dissociation off-rates, were also constructed. A mapping of the chemical properties of the side chains onto the Affibody scaffold surface reveals three distinct adjacent surface areas of positively charged surface, nonpolar surface and a polar surface, which presumably match a corresponding surface epitope on the protofibrils. The results demonstrate that the engineered Aβ42cc is a suitable antigen for directed evolution of affinity reagents with specificity for wild type Aβ42 protofibrils.
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| 18. |
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| 19. |
- Wahlberg, Elisabet, 1963-
(författare)
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Structure determination and thermodynamic stabilization of an engineered protein-protein complex
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interaction between two 6 kDa proteins has been investigated. The studied complex of micromolar affinity (Kd) consists of the Z domain derived from staphylococcal protein A and the related protein ZSPA-1, belonging to a group of binding proteins denoted affibody molecules generated via combinatorial engineering of the Z domain. Affibody-target protein complexes are good model systems for structural and thermodynamic studies of protein-protein interactions. With the Z:ZSPA-1 pair as a starting point, we determined the solution structure of the complex and carried out a preliminary characterization of ZSPA-1. We found that the complex contains a rather large (ca. 1600 Å2) interaction interface with tight steric and polar/nonpolar complementarity. The structure of ZSPA-1 in the complex is well-ordered in a conformation that is very similar to that of the Z domain. However, the conformation of the free ZSPA-1 is best characterized by comparisons with protein molten globules. It shows a reduced secondary structure content, aggregation propensity, poor thermal stability, and binds the hydrophobic dye ANS. This molten globule state of ZSPA-1 is the native state in the absence of the Z domain, and the ordered state is only adopted following a stabilization that occurs upon binding. A more extensive characterization of ZSPA-1 suggested that the average topology of the Z domain is retained in the molten globule state but that it is represented by a multitude of conformations. Furthermore, the molten globule state is only marginally stable, and a significant fraction of ZSPA-1 exists in a completely unfolded state at room temperature. A complete thermodynamic characterization of the Z:ZSPA-1 pair suggests that the stabilization of the molten globule state to an ordered three helix structure in the complex is associated with a significant conformational entropy penalty that might influence the binding affinity negatively and result in an intermediate-affinity (µM) binding protein. This can be compared to a dissociation constant of 20-70 nM for the complex Z:Fc of IgG where Z uses the same binding surface as in Z:ZSPA-1. Structure analyses of Z in the free and bound state reveal an induced fit response upon complex formation with ZSPA-1 where a conformational change of several side chains in the binding surface increases the accessible surface area with almost 400 Å2 i.e. almost half of the total interaction surface in the complex. Two cysteine residues were introduced at specific positions in ZSPA-1 for five mutants in order to stabilize the conformation of ZSPA-1 by disulfide bridge formation. The mutants were thermodynamically characterized and the binding affinity of one mutant showed an improvement by more than a factor of ten. The improvement of the introduced cysteine bridge correlates with an increase in binding enthalpy rather than with entropy. Further analysis of the binding entropy suggests that the conformational entropy change in fact is reduced but its favorable contribution is opposed by a less favorable desolvation enthalpy change. These studies illustrate the structural and thermodynamic complexity of protein-protein interactions, but also that this complexity can be dissected and understood. In this study, a comprehensive characterization of the ZSPA-1 affibody has gained insight into the intricate mechanisms involved in complex formation. These theories were supported by the design of a ZSPA-1 mutant with improved binding affinity.
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| 20. |
- Wahlberg, Jeanette, 1969-, et al.
(författare)
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Environmental factors related to the induction of beta-cell autoantibodies in 1-yr-old healthy children
- 2005
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Ingår i: Pediatric Diabetes. - : John Wiley & Sons. - 1399-543X .- 1399-5448. ; 6:4, s. 199-205
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Tidskriftsartikel (refereegranskat)abstract
- We studied environmental risk factors which might contribute to the development of beta-cell autoantibodies in healthy children. Here, we investigated 6000 randomly selected children from the large All Babies in Southeast Sweden (ABIS) cohort, including 17 055 newborns recruited between 1997 and 1999. Questionnaires at birth and at 1 yr of age and the levels of autoantibodies to glutamic acid decarboxylase (GADA) and autoantibodies to tyrosine phosphatase (IA-2A) at 1 yr of age were analyzed. The 99th percentile cutoff for autoantibodies was proposed to identify children at risk of type 1 diabetes (T1D) and the 90th percentile cutoff to identify children in whom beta-cell autoimmunity has been induced. Using the 90th percentile cutoff level, 1156 children had either IA-2A (n = 574) or GADA (n = 582), while 126 children had both GADA and IA-2A. When the 99th percentile cutoff level was used, 114 children had either IA-2A (n = 57) or GADA (n = 57), and six children had both GADA and IA-2A. In logistic regression analysis, celiac disease in grandparents [odds ratio (OR) 2.2] and maternal gastrointestinal infection (OR 1.1) represented a risk for simultaneous occurrence of both IA-2A and GADA above the 90th percentile. Birth in spring (March to May) (OR 1.5) and male gender (OR 1.3) were risk factors for induction of IA-2A. Mother's low education represented a risk for induction of IA-2A (OR 1.5) and GADA (OR 1.4). T1D in first-degree relatives increased the risk for beta-cell autoimmunity above the 99th percentile (OR 2.6), whereas type 2 diabetes in grandparents was associated with GADA (OR 2.1). Exposure to cow's milk formulas <2 months of age implied an OR of 2.9 for IA-2A above the 99th percentile.
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| 21. |
- Wahlberg, Niklas, et al.
(författare)
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Timing major conflict between mitochondrial and nuclear genes in species relationships of Polygonia butterflies (Nymphalidae: Nymphalini)
- 2009
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Ingår i: BMC Evolutionary Biology. - : Springer Science and Business Media LLC. - 1471-2148. ; 92:9
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Tidskriftsartikel (refereegranskat)abstract
- Background Major conflict between mitochondrial and nuclear genes in estimating species relationships is an increasingly common finding in animals. Usually this is attributed to incomplete lineage sorting, but recently the possibility has been raised that hybridization is important in generating such phylogenetic patterns. Just how widespread ancient and/or recent hybridization is in animals and how it affects estimates of species relationships is still not well-known. Results We investigate the species relationships and their evolutionary history over time in the genus Polygonia using DNA sequences from two mitochondrial gene regions (COI and ND1, total 1931 bp) and four nuclear gene regions (EF-1α, wingless, GAPDH and RpS5, total 2948 bp). We found clear, strongly supported conflict between mitochondrial and nuclear DNA sequences in estimating species relationships in the genus Polygonia. Nodes at which there was no conflict tended to have diverged at the same time when analyzed separately, while nodes at which conflict was present diverged at different times. We find that two species create most of the conflict, and attribute the conflict found in Polygonia satyrus to ancient hybridization and conflict found in Polygonia oreas to recent or ongoing hybridization. In both examples, the nuclear gene regions tended to give the phylogenetic relationships of the species supported by morphology and biology. Conclusion Studies inferring species-level relationships using molecular data should never be based on a single locus. Here we show that the phylogenetic hypothesis generated using mitochondrial DNA gives a very different interpretation of the evolutionary history of Polygonia species compared to that generated from nuclear DNA. We show that possible cases of hybridization in Polygonia are not limited to sister species, but may be inferred further back in time. Furthermore, we provide more evidence that Haldane's effect might not be as strong a process in preventing hybridization in butterflies as has been previously thought.
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| 22. |
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| 23. |
- Weingartner, Elisabet, et al.
(författare)
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Dynamics of host plant use and species diversity in Polygonia butterflies (Nymphalidae)
- 2006
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Ingår i: J Evol Biol. - 1010-061X. ; 19:2, s. 483-91
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Tidskriftsartikel (refereegranskat)abstract
- The ability of insects to utilize different host plants has been suggested to be a dynamic and transient phase. During or after this phase, species can shift to novel host plants or respecialize on ancestral ones. Expanding the range of host plants might also be a factor leading to higher levels of net speciation rates. In this paper, we have studied the possible importance of host plant range for diversification in the genus Polygonia (Nymphalidae, Nymphalini). We have compared species richness between sistergroups in order to find out if there are any differences in number of species between clades including species that utilize only the ancestral host plants ('urticalean rosids') and their sisterclades with a broader (or in some cases potentially broader) host plant repertoire. Four comparisons could be made, and although these are not all phylogenetically or statistically independent, all showed clades including butterfly species using other or additional host plants than the urticalean rosids to be more species-rich than their sisterclade restricted to the ancestral host plants. These results are consistent with the theory that expansions in host plant range are involved in the process of diversification in butterflies and other phytophagous insects, in line with the general theory that plasticity may drive speciation.
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| 24. |
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| 25. |
- Weingartner, Elisabet, 1969-
(författare)
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Phylogenetic perspective on host plant use, colonization and speciation in butterflies
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis we have studied speciation in three butterfly genera Polygonia (Nymphalidae, Nymphalini), Pararge (Nymphalidae, Satyrinae) and Celastrina (Lycaenidae: Polyommatinae). In the first paper a dated phylogeny, based on molecular data, of Polygonia was constructed. We found strong conflict between the nDNA and mtDNA datasets. Possibly this can be explained by ancestral and recent hybridizations between contemporary taxa. The results point to the importance in using different markers when we try to resolve evolution of taxa. In the second paper a sister group comparison was made in order to discover whether host plant range has had an effect on species diversity in Polygonia. Our result indicated higher diversification rates in clades which included species with larvae feeding on different, or additional, plants compared to the ”urticalean rosids” specialists. In the third paper our focus was on the colonization abilities in polyphagous butterflies. The haplotype structures of the mtDNA cytochromeoxidase I (COI) within the Nearctic species of Celastrina as well as within P. c-album and P. faunus were analysed in a network. We found little variation in Celastrina and P. c-album. This results imply that the genera have expanded recently and rapidly. There are indications of differentiation in COI in Celastrina and, possibly, host plant use is involved. However, in P. faunus we found structure among the haplotypes. We believe that several different haplotypes of this species have been preserved during glaciations in the Nearctic. In the fourth paper the evolution of the grassfeeding Pararge was analysed. The phylogeny was based on the mtDNA COI and the nDNA wingless (wgl) and times of divergences were calculated. We found a deep divergence between the European and Moroccan populations of P. aegeria which indicates the importance of the Mediterranean as a barrier for gene flow.
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