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- Mohan Pawar, Prashant, et al.
(författare)
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In muro deacetylation of xylan affects lignin properties and improves saccharification of aspen wood
- 2017
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 10:1, s. Art nr 98-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lignocellulose from fast growing hardwood species is a preferred source of polysaccharides for advanced biofuels and "green" chemicals. However, the extensive acetylation of hardwood xylan hinders lignocellulose saccharification by obstructing enzymatic xylan hydrolysis and causing inhibitory acetic acid concentrations during microbial sugar fermentation. To optimize lignocellulose for cost-effective saccharification and biofuel production, an acetyl xylan esterase AnAXE1 from Aspergillus niger was introduced into aspen and targeted to cell walls. Results: AnAXE1-expressing plants exhibited reduced xylan acetylation and grew normally. Without pretreatment, their lignocellulose yielded over 25% more glucose per unit mass of wood (dry weight) than wild-type plants. Glucose yields were less improved (+7%) after acid pretreatment, which hydrolyses xylan. The results indicate that AnAXE1 expression also reduced the molecular weight of xylan, and xylan-lignin complexes and/or lignin co-extracted with xylan, increased cellulose crystallinity, altered the lignin composition, reducing its syringyl to guaiacyl ratio, and increased lignin solubility in dioxane and hot water. Lignin-associated carbohydrates became enriched in xylose residues, indicating a higher content of xylo-oligosaccharides. Conclusions: This work revealed several changes in plant cell walls caused by deacetylation of xylan. We propose that deacetylated xylan is partially hydrolyzed in the cell walls, liberating xylo-oligosaccharides and their associated lignin oligomers from the cell wall network. Deacetylating xylan thus not only increases its susceptibility to hydrolytic enzymes during saccharification but also changes the cell wall architecture, increasing the extractability of lignin and xylan and facilitating saccharification.
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| 2. |
- Kadej, Marcin, et al.
(författare)
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Sex pheromones as a tool to overcome the Wallacean shortfall in conservation biology: a case of Elater ferrugineus Linnaeus, 1758 (Coleoptera: Elateridae)
- 2015
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Ingår i: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 19:1, s. 25-32
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Tidskriftsartikel (refereegranskat)abstract
- The “Wallacean shortfall”—lack of distributional information—is one of the main problems when trying to assess the threats to and planning conservation strategies for many invertebrate species. Based on published and unpublished records since 1840, as well as on our own field survey, we attempted to estimate if and to what extent the use of pheromone traps increased the detectability of a rare, saproxylic click beetle Elater ferrugineus. The significant increase in the number of records in 2011–2013 shows that the pheromone method made it much easier to detect the occurrence of the species. Advantages of the pheromone method are that it does not disturb the habitat, can be used by non-specialists, is less costly and less time-consuming, and thus providing a useful tool for conservation research (studying biology, ecology and genetics of local populations).
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| 3. |
- Zauli, Agnese, et al.
(författare)
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Assessing the taxonomic status of Osmoderma cristinae (Coleoptera : Scarabaeidae), endemic to Sicily, by genetic, morphological and pheromonal analyses
- 2016
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Ingår i: Journal of Zoological Systematics and Evolutionary Research. - : Hindawi Limited. - 0947-5745 .- 1439-0469. ; 54:3, s. 506-514
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Tidskriftsartikel (refereegranskat)abstract
- Resolving complexes of closely related and cryptic insect species can be challenging, especially when dealing with rare and protected taxa that are difficult to collect for genetic and morphological analyses. Until recently, populations of the genus Osmoderma (Scarabaeidae), widespread in Europe, were treated as a single species O. eremita (Scopoli, 1763) in spite of observed geographic variation in morphology. A previous survey using sequence data from the mtDNA cytochrome C oxidase I gene (COI) revealed the occurrence of at least two distinct lineages within this species complex: O. eremita in the west and O. barnabita Motschulsky, 1845, in the east. Interestingly, beetles confined to Sicily have been described as a distinct species, O. cristinae Sparacio, 1994, based on morphological traits. Only few Sicilian specimens were included in the former genetic analysis, and the results led to a still questionable taxonomic rank for these populations. To explore the robustness of the previous taxonomic arrangement for O. cristinae, a combination of genetic, morphological and pheromonal analyses was used. A 617-bp fragment of the COI gene, aligned with O. cristinae and O. eremita sequences already available in GenBank, showed a clear genetic divergence between the two species (interspecific mean distance = 6.6%). Moreover, results from AFLP markers sustained the distinction of the two species. In addition, geometric morphometric analyses of the shape of male genitalia revealed a clear differentiation between the two species. Via scent analysis and field trapping, we demonstrated the production of the sex pheromone (R)-(+)-γ-decalactone by males of O. cristinae, the attraction by conspecific individuals (mostly females) to this compound, and a lack of antagonistic effect of (S)-(-)-γ-decalactone. The fact that O. eremita and O. eremita use the same compound for mate finding suggests that this sex pheromone has not undergone a differentiation and probably the allopatry of these two species compensates for the absence of a mechanism to avoid cross-attraction. Our genetic and morphological data support the divergence of the two species and confirm the species status for O. cristinae, while sex pheromones are confirmed to be invariant among different species of the genus Osmoderma.
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