Liikide lahknemine ja nende piiritlemine valitud lihheniseerunud seente rühmades perekonnas Parmeliaceae (Ascomycota)

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Eluslooduse süsteemi põhiühik on liik, kuid seni pole õnnestunud rakendada ühesuguseid liigikriteeriume kogu eluslooduse mitmekesisusele. Ebapüsiv või ekslik taksonoomia võib põhjustada isegi mittevajalikke rahalisi kulutusi, näiteks kaitsealuste, invasiivsete või patogeensete liikide piiritlemisel või valestimääramisel. Samblikud on sümbiootilised organismid, koosnedes vähemalt kahest komponendist – seenest ning selle sees elavast ja fotosünteesivast rohevetikast ja/või tsüanobakterist. Süstemaatiliselt käsitletakse samblike seentena, mis toituvad oma partneri fotosünteesiproduktist. Mitmeid samblike saab kasutada keskkonna kvaliteedi hindamiseks, kuid paljude liikide määramine on jätkuvalt keeruline ning nende piirid ebaselged. Pärilikkusaine ehk DNA uuringud võimaldavad liigikontseptsioonide ning liigipiiride ühtlustamist, rakendades liigile ühise eellase (monofüleetilisuse) kriteeriumit. Uurisin oma doktoritöös sugulussuhted ning liikide piiritlemist kolmes sambliku moodustava seene rühmas, kasutades morfoloogilisi, keemilisi, anatoomilisi ja geneetilisi tunnuseid. Lisaks küsisin, kas samblike on võimalik määrata kasutades DNA järjestusi. Oma töös leidsin, et paljud morfoloogiliste tunnuste alusel kirjeldatud samblikud ei esinda jätkuvalt loomulikke, geneetiliselt eristunud liike ning seetõttu vajavad taksonoomilist korrastamist. Rebasesamblikud ja habesamblikud sektsioonist Usnea esindavad hiljuti lahknenud noorte liikide komplekse, mida iseloomustavad konfliktne geneetiline info ja ebaselged liigipiirid. Tõestasin, et sellistes rühmades on põhjendatud uudsete liigipuu ja liikide piiritlemise meetodite kasutamine. Helksamblike liigid on seevastu hästi eristunud ning kasutatavad tunnused valdavalt asjakohased. Uurimus näitas, et isendite üldine haabitus ja paljunemisviis ei pruugi olla piisavad nende samblike õigeks määramiseks ning lisaks tuleks uurida samblike keemiat ja kasutada DNA infot.Species is a fundamental unit in biology but debate continues over boundaries, numbers of species, and identification methods. Unstable or erroneous taxonomy can even have financial ramifications when, for example, protected, invasive, or pathogenic species are falsely identified or delimited. Lichens are systematically considered as mostly sac fungi that are able to form intimate and long-term symbiotic associations with photosynthetic algae or cyanobacteria. Lichens are known for their tolerance for extreme conditions in arctic areas, and at the same time, for their vulnerability – many lichens can be used as bio-indicators in monitoring environmental quality. However, accurate identification of lichenized fungal species remains challenging due to complex diagnostic characters and unsettled species boundaries in many groups. In my doctorate thesis I studied species boundaries and evolutionary relationships in lichenized fungal genera Cetrelia, Usnea section Usnea, and Vulpicida. Also I attempted to identify lichenized fungal species using DNA sequences, and estimate its usage and accuracy. I found that many taxa of lichen fungi are still in need of taxonomic revision. The genera Vulpicida and Usnea section Usnea represent recently diverged species complexes with conflicting genetic signal and unclear species relationships. Here, I established that using novel species tree and species delimitation methods should be preferred over traditional gene tree approach. Cetrelia, on the other hand, represented a lengthier evolutionary history, with relatively well-circumscribed species and justified diagnostic characters. I found that the general appearance of specimens and their reproductive mode might not always be sufficient in delimiting genetically isolated fungal lineages. DNA-based identification could be used as an alternative species identification method but is efficient in a system of well-circumscribed taxa and a high-quality reference database

Transitoorne epileptiline amneesia

Mööduva mäluhäire võimalikke põhjusi on palju. Isoleeritud transitoorse amneesia episoodid võivad olla ka epilepsi kliiniliseks väljenduseks. Kirjanduses on selle kohta kasutusel termin transitoorne epileptiline amneesia (TEA). TEA-le on iseloomulikud hilisemas eas algavad lühikese kestusega, sagedased ning tihti ärkamisel tekkivad mööduvad mäluhäired. Enamusel TEA-patsientidel (70%) esineb amneesiaatakkide kõrval ka teisi temporaalsagara lähtega epileptilisi avaldusi, kuid mööduv amneesia on ainsaks epilepsia kliiniliseks väljenduseks umbes kolmandikul TEApatsientidel. TEA on kliiniliselt oluline probleem, kuna korrektse diagnoosi korral on esinevatele mäluhäiretele olemas tõhus põhjuslik ravi. Artiklis on kirjeldatud TEA haigusjuhtu vanemal naisterahval, kelle probleemiks olid 2 aasta jooksul esinenud nn mälulüngad, mis häirisid patsienti oluliselt ning millele ei oldud seni põhjust leitud. Eesti Arst 2009; 88(2):125−13

Properties of cellulose nanofibre networks prepared from never-dried and dried paper mill sludge

Paper mills yield large volumes of sludge materials which pose an environmental and economic challenge for disposal, despite the fact that they could be a valuable source for cellulose nanofibres (CNF) production. The aim of the study was to evaluate the production process and properties of CNF prepared by mechanical fibrillation of never-dried and dried paper mill sludge (PMS). Atomic force microscopy (AFM) showed that average diameters for both never-dried and dried paper sludge nanofibres (PSNF) were less than 50 nm. The never-dried and dried sludge nanofibres showed no statistical significant difference (p > 0.05) in strength ∼92 MPa, and ∼85 MPa and modulus ∼11 GPa and ∼10 GPa. The study concludes that paper mill sludge can be used in a dried state for CNF production to reduce transportation and storage challenges posed on industrial scale

Effects of Water Soaking–drying Cycles on Thermally Modified Spruce Wood–plastic Composites.

The overall aim of this work was to gain more insight on the potential of modified wood (TMW) components for use in wood–thermoplastic composites (WPCs). Laboratory-scale TMWPCs were produced, and the effects of severe water soaking–drying cycles on the samples were studied. Water sorption behavior and resulting dimensional and micromorphological changes were also studied, and the results were compared with those of unmodified wood–plastic composites (UWPCs) used as control. The TMW was prepared by cutting a spruce board into half and subjecting one-half to an atmosphere of superheated steam at atmospheric pressure with a peak temperature of 210°C, with the other unmodified wood (UW) half as a control. The TMW and UW components were then prepared by a Wiley mill and thereafter sifted into smaller (mesh 0.20-0.40 mm) and larger (mesh 0.40-0.63 mm) size fractions. A portion of the wood components were also subjected to thermal extraction (HE). Composite samples with these different wood components, polypropylene (PP) matrix, and maleated PP (MAPP) as coupling agent (50/48/2 wood/PP/MAPP ratio by weight) were then prepared by using a Brabender mixer followed by hot pressing. The matching micromorphology of the composites before and after the soaking–drying cycles was analyzed using a surface preparation technique based on ultraviolet-laser ablation combined with scanning electron microscopy. The results of the water absorption tests showed, as hypothesized, a significantly reduced water absorption and resulting thickness swelling at the end of a soaking cycle for the TMWPCs compared with the controls (UWPCs). The water absorption was reduced with about 50-70% for TMWPC and 60-75% for HE-TMWPC. The thickness swelling for TMWPCs was reduced with about 40-70% compared with the controls. Similarly, the WPCs with HE-UW components absorbed about 20-45% less moisture and showed a reduced thickness swelling of about 25-40% compared with the controls. These observations also were in agreement with the micromorphology analysis of the composites before and after the moisture cycling which showed a more pronounced wood–plastic interfacial cracking (de-bonding) as well as other microstructure changes in the controls compared with those prepared with TMW and HE-UW components. Based on these observations, it is suggested that these potential bio-based building materials show increased potential durability for applications in harsh outdoor environments, in particular TMWPCs with a well-defined and comparably small size fractions of TMW components.

International organizations, advocacy coalitions, and domestication of global norms : Debates on climate change in Canada, the US, Brazil, and India

National climate policies are shaped by international organizations (IOs) and global norms. Drawing from World Society Theory and the Advocacy Coalition Framework (ACF), we develop two related arguments: (1) one way in which IOs can influence national climate policy is through their engagement in mass-mediated national policy debates and (2) national organizations involved in the policy process may form advocacy coalitions to support or oppose the norms promoted by IOs. To examine the role of IOs in national policy debates and the coalitions that support and oppose them, we use discourse network analysis (DNA) on over 3500 statements in 11 newspapers in Canada, the United States (US), Brazil, and India. We find that in the high-income countries that are high per capita emitters (Canada and the US), IOs are less central in the policy debates and the discourse network is strongly clustered into competing advocacy coalitions. In the lower-income countries that are low per capita emitters (Brazil and India), IOs are more central and the discourse network is less clustered. Relating these findings to earlier research, we suggest that the differences we find between high and low per capita emitters may be to some extent generalizable to the relevant country groups beyond our four cases.Peer reviewe

Properties of cellulose nanofibre networks prepared from never-dried and dried paper mill sludge

Paper mills yield large volumes of sludge materials which pose an environmental and economic challenge for disposal, despite the fact that they could be a valuable source for cellulose nanofibres (CNF) production. The aim of the study was to evaluate the production process and properties of CNF prepared by mechanical fibrillation of never-dried and dried paper mill sludge (PMS). Atomic force microscopy (AFM) showed that average diameters for both never-dried and dried paper sludge nanofibres (PSNF) were less than 50 nm. The never-dried and dried sludge nanofibres showed no statistical significant difference (p > 0.05) in strength ∼92 MPa, and ∼85 MPa and modulus ∼11 GPa and ∼10 GPa. The study concludes that paper mill sludge can be used in a dried state for CNF production to reduce transportation and storage challenges posed on industrial scale

Soil-related habitat specialization in dipterocarp rain forest tree species in Borneo

Summary 1 We conducted a field experiment to test whether aggregated spatial distributions were related to soil variation in locally sympatric tree species in the rain forests of Sarawak, Malaysia. Dryobalanops aromatica , Shorea laxa , and Swintonia schwenkii are naturally aggregated on low-fertility humult ultisols, Dryobalanops lanceolata and Hopea dryobalanoides on moderate-fertility udult ultisols and Shorea balanocarpoides is found on both soil types. 2 Seedlings of all six species were grown in a nested-factorial experiment for 20 months in humult and udult soils in gaps and in the understorey to test for soil-specific differences in performance. Phosphorus addition was used to test for effects due to P-limitation. 3 Four species showed significantly higher growth on their natural soils, but one humultsoil species ( D. aromatica ) and the broadly distributed species were not significantly affected by soil type. 4 One udult-soil species, D. lanceolata , had both lower relative growth rate and lower mycorrhizal colonization on humult soil. However, humult soils also had lower levels of Ca, Mg, K, N and probably water availability. 5 The overall ranking of growth rates among species was similar on the two soils. Growth rates were strongly positively correlated with leaf area ratio and specific leaf area among species in both soils. With the exception of D. aromatica , species of the higher-nutrient soils had higher growth rates on both soils. 6 Although P addition led to elevated soil-P concentrations, elevated root-and leaf-tissue P concentrations on both soils, there was no significant growth enhancement and therefore no evidence that P availability limits the growth or constrains the distribution of any of the six species in the field. Differences in soil water availability between soils may be more important. 7 Our results suggest that habitat-mediated differences in seedling performance strongly influence the spatial distributions of tropical trees and are therefore likely to play a key role in structuring tropical rain forest communities

Back to the future of soil metagenomics

JN was funded by a fellowship from the French MENESR.Peer reviewedPeer Reviewe

Carbohydrate esterase family 16 contains fungal hemicellulose acetyl esterases (HAEs) with varying specificity

Acetyl esterases are an important component of the enzymatic machinery fungi use to degrade plant biomass and are classified in several Carbohydrate Esterase families of the CAZy classification system. Carbohydrate Esterase family 16 (CE16) is one of the more recently discovered CAZy families, but only a small number of its enzyme members have been characterized so far, revealing activity on xylan-derived oligosaccharides, as well as activity related to galactoglucomannan. The number of CE16 genes differs significantly in the genomes of filamentous fungi. In this study, four CE16 members were identified in the genome of Aspergillus niger NRRL3 and it was shown that they belong to three of the four phylogenetic Clades of CE16. Significant differences in expression profiles of the genes and substrate specificity of the enzymes were revealed, demonstrating the diversity within this family of enzymes. Detailed characterization of one of these four A. niger enzymes (HaeA) demonstrated activity on oligosaccharides obtained from acetylated glucuronoxylan, galactoglucomannan and xyloglucan, thus establishing this enzyme as a general hemicellulose acetyl esterase. Their broad substrate specificity makes these enzymes highly interesting for biotechnological applications in which deacetylation of polysaccharides is required.Peer reviewe