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- Hedrén, Mikael, et al.
(författare)
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Asymmetric contributions of seed and pollen to gene dispersal in the marsh orchid Dactylorhiza umbrosa in Asia Minor
- 2021
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Ingår i: Molecular Ecology. - : Wiley. - 0962-1083 .- 1365-294X. ; 30:8, s. 1791-1805
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Tidskriftsartikel (refereegranskat)abstract
- Orchids differ from other plants in their extremely small and partly air-filled seeds that can be transported long distances by wind. Seed dispersal in orchids is expected to contribute strongly to overall gene flow, and orchids generally express low levels of genetic differentiation between populations and low pollen to seed flow ratios. However, studies in orchids distributed in northern Europe have often found a poor geographic structuring of genetic variation. Here, we studied geographic differentiation in the marsh orchid Dactylorhiza umbrosa, which is widely distributed in upland regions from Asia Minor to Central Asia. These areas were less affected by Pleistocene ice ages than northern Europe and the orchid should have been able to survive the last ice age in local refugia. In the plastid genome, which is dispersed by seeds, populations at close distance were clearly divergent, but the differentiation still increased with geographic distance, and a significant phylogeographic structure had developed. In the nuclear genome, which is dispersed by both seeds and pollen, populations showed an even stronger correlation between genetic and geographic distance, but average levels of differentiation were lower than in the plastid genome, and no phylogeographic structure was evident. Combining plastid and nuclear data, we found that the ratio of pollen to seed dispersal (mp/ms) decreases with physical distance. Comparison with orchids that grow in parts of Europe that were glaciated during the last ice suggests that a balanced structure of genetic diversity develops only slowly in many terrestrial orchids, despite efficient seed dispersal.
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| 2. |
- Awad, Wael, et al.
(författare)
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Structural and Biophysical Characterization of Human EXTL3 : Domain Organization, Glycosylation, and Solution Structure
- 2018
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 57:7, s. 1166-1177
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Tidskriftsartikel (refereegranskat)abstract
- Heparan sulfate proteoglycans are proteins substituted with one or more heparan sulfate (HS) polysaccharides, found in abundance at cell surfaces. HS chains influence the activity of many biologically important molecules involved in cellular communication and signaling. The exostosin (EXT) proteins are glycosyltransferases in the Golgi apparatus that assemble HS chains on HSPGs. The EXTL3 enzyme mainly works as an initiator in HS biosynthesis. In this work, human lumenal N-glycosylated EXTL3 (EXTL3ΔN) was cloned, expressed in human embryonic kidney cells, and purified. Various biophysical and biochemical approaches were then employed to elucidate the N-glycosylation sites and the function of their attached N-glycans. Furthermore, the stability and conformation of the purified EXTL3ΔN protein in solution have been analyzed. Our data show that EXTL3ΔN has N-glycans at least at two positions, Asn290 and Asn592, which seem to be critical for proper protein folding and/or release. EXTL3ΔN is quite stable, as high temperature (∼59 °C) was required for denaturation. Deconvolution of the EXTL3ΔN far-UV CD spectrum revealed a substantial fraction of β sheets (25%) with a minor proportion of α-helices (14%) in the secondary structure. Solution small-angle X-ray scattering and dynamic light scattering revealed an extended structure suggestive of a dimeric arrangement and consisting of two distinct regions, narrow and broad, respectively. This is consistent with bioinformatics analyses suggesting a 3-domain structure with two glycosyltransferase domains and a coiled-coil domain.
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| 3. |
- Birkedal, Sven, et al.
(författare)
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Dagfjärilar en fältguide
- 2019
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- I denna nya fältguide till svenska dagfjärilar beskrivs drygt 180 arter, underarter, former och tillfälliga besökare. Boken är rikt illustrerad och fjärilarna åtföljs av fotografier på hane, hona och undersida jämte grafiska bilder över utbredningar och flygtider. Boken är den tredje i Naturcentrums serie om växter och djur i Sverige. Tidigare har "Lavar - en fältguide" och "Mossor en fältguide" utgivits.Ett kort inledande avsnitt beskriver bokens tillkomst, hur den är uppbyggd, terminologi, litteratur samt lite om fjärilsskådning. Därefter följer bokens huvuddel som utgörs av artbeskrivningarna och ca 1.000 illustrationer ledsagar läsaren. Boken, som omfattar 200 sidor, är framtagen av Sven Birkedal, naturälskare och fotograf från Åhus. Fjärilsforskaren Nils Ryrholm har stått för kompletterade texter och beskrivningar, vetenskaplig granskning, utbredningskartor, flygtider, m. m.
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