1,720,974 research outputs found
Development of Lepidium campestre into a new oil and catch crop
Full text linkA growing world population and dwindling fossil oil reserves demand an increase in the world plant oil production. The possibility to increase the area of cultivated land is limited due to the shortage of arable land. Also, the possibility for increasing the oil content in the limited number of cultivated oil crops is restricted. New, high-yielding oil crops, which can be grown in areas where no other oil crops can grow and have less environmental impact, need to be developed. It is preferable that such new oil crops would allow us to tailor-make the oil composition in planta for food, fuel or industrial applications. In Sweden, the main oil crop cultivated is winter rapeseed, which, due to weak winter hardiness, only can be grown in southern Sweden. Developing a new winter-hardy oilseed crop would extend the plant oil production in Sweden and other cold climate regions. Lepidium campestre is a wild Brassica species. It is very winter hardy, high-yielding, has an upright stature and synchronous flowering. Moreover, it is biennial, and thus being suitable as a catch crop. However, it needs to be domesticated first so that it possesses all important agronomic traits necessary for being a successful agricultural crop.
The aim of this thesis was to improve some properties of L. campestre by genetic engineering with focus on: the seed oil content, pod shatter, seed oil composition and wax ester production in the seed oil. In order to enable genetic engineering of this wild species, a well-functioning regeneration and transformation protocol was first developed, which has greatly facilitated the subsequent genetic improvements of the target traits of the species. Through RNAi-down-regulation of the FAD2 and FAE1 genes, transgenic lines with oxidative stable oil high in oleic acid were generated, indicating the potential of the species for being used for food oil purposes. Moreover, transgenic lines with increased seed oil content were developed by expressing either the AtWRI1 or AtHb2 or BvHb2 gene. Transgenic lines with pod shatter resistance were produced by RNAi down-regulation of the IND gene. Wax esters were produced in this species by expression of the jojoba wax synthesis genes, showing the potential of the species as a new platform for industrial oil production. These transgenic lines are valuable materials for further breeding of this species
Factors affecting Agrobacterium transformation in oat
Full text linkOat (Avena sativa L.) is one of the crops that have been cultivated by mankind for the longest time (Lásztity, 1998) and today it is an important and traditional agricultural crop in Northern Europe (Bräutigam et al., 2005). In Sweden, most of the oat is used as feed (Bräutigam et al., 2005), but with a superior amino acid composition of the oat proteins (Lásztity, 1998), a high content of desirable soluble fibers (β-glucans), essential vitamins and minerals (Sadiq Butt et al., 2008) and antioxidants (Ryan et al. 2007) the interest in using oats for human consumption has increased (Carlsson, Personal conversation). In comparison to other cereals, oat has a much higher content of lipids. The oil is interesting because its energy content is high, while its content of saturated fatty acids is relatively low. A disadvantage, which may prevent an increase in using oat as food, is the imbalance of Omega-6/Omega-3 fatty acids. The amount of Omega-6 fatty acids is much higher than the amount of Omega-3 fatty acids (Welch & Legett, 1997). The imbalance in the fatty acid composition has shown to be a possible factor behind the increasing number of cases of cardiovascular disease, cancer, diabetes, asthma, depression, obesity, autoimmune diseases and rheumatism in the western countries (Simopoulos, 2004).
With the help of transformation, it is possible to increase the amount of Omega-3 fatty acids, and thus get a better Omega-6/Omega-3-balance in oat. Omega-3 fatty acids have also shown to be potential therapeutic agents for autoimmune and inflammatory diseases (Simopoulos, 2002), the main reason behind the increased interest in using oat as food.
Transformation allows an increase in Omega-3 fatty acids in oats, but previous studies concerning transformation of Avena sativa L. has resulted in low transformation frequencies. Oat is a monocotyledonous crop, not a normal host for Agrobacterium; it is thus difficult to be infected. The conditions have to be optimal for a successful transformation to occur.
The aim of this work has been to examine various factors affecting oat transformation, and to develop a functional transformation protocol.
Explants from the hypocotyl of the oat cultivar Matilda were infected by Agrobacterium-mediated transformation. In total, 15 batches of transformation were carried out, in which different combinations of bacterial strains, vectors and media were tested. GUS- and GFP assays were conducted to confirm Agrobacterium infection of the explants.
No GUS expression was achieved in the GUS assays, but no certain conclusion can be drawn from the result. Endogenous GUS-like activity is triggered by low pH-values, but a raised pH-value may not only suppress the expression of endogenous GUS, but also the expression of true GUS.
The explants analyzed for GFP expression exhibited whitish-colored spots, but further cultivation and repeated assays of the explants is necessary to confirm GFP expression.
Further trials are needed in order to obtain a well-functioning oat transformation protocol
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Bladstruktur och lokalisering av transgenprotein i korn
Full text linkBarley is one of the most important cereals cultivated in the Nordic countries. Climate change brings warmer and moisture climate which favors fungal diseases. In the cropland barley can be seriously infested with hard fungus attack. Since it is important that the yield bears a high quality it is of great importance to find varieties more resistant to attacks.
Pathogenesis-related (PR) proteins are stress proteins induced in the plant in response to infection and abiotic stress (van Loon, 1997). PRs are shown to have antimicrobial activity differing between bacteria, fungi and oomycetes (Tandrup Poulsen, 2001). Among the 17 PR-families (van Loon et al., 1994, 2006) PR-5 is one of the most abundant ones in barley (Tandrup Poulsen, 2001, van Loon et al., 2006).
Studies have shown that PR-5 exists naturally in the ground tissue of leaves, but not in the epidermis (Gregersen et al., 1997). In the epidermal cell walls an epidermis-specific promoter for PR-5 has been placed in front of the gene encoding PR-5, this to achieve a more resistant cultivar of barley. Enhanced resistance has been demonstrated, but it is not confirmed that this resistance is due to expression of PR-5 in epidermis (Santén et al., unpublished, Tandrup Poulsen, 2001). In the modified lines, preliminary studies have shown irregular structure of epidermis (Santén et al., unpublished).
The aim of the study was to establish whether there were structural differences between regular and modified barley, and to localize PR-5 in epidermis. Counterstaining was used to be able to study the leaf structure in microscope, and immunocytochemistry was used to localize PR-5.
Results showed irregular cell structure in epidermis, and in a few cases even in the ground tissue, of modified barley. Due to failure in method, unspecific binding of the antibody visualizer occurred and no confident result could be established regarding the localization of PR-5. Nothing indicates an existence of PR-5 in epidermal cell walls of modified barley. This could be a result of a non-working method, undetectable levels of PR-5 or that the gene encoding PR-5 is expressed as mRNA but not translated to protein.
Occurrence of PR-5 has been demonstrated in epidermal cells of infected material. This detection could be due to the fact that the gene needs an infection to be
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expressed as the protein. More studies are necessary to establish whether the showed enhanced resistance is due to expression of PR-5 in epidermis
Development of Lepidium campestre into a new oil and catch crop [Elektronisk resurs]
No full textA growing world population and dwindling fossil oil reserves demand an increase in the world plant oil production. The possibility to increase the area of cultivated land is limited due to the shortage of arable land. Also, the possibility for increasing the oil content in the limited number of cultivated oil crops is restricted. New, high-yielding oil crops, which can be grown in areas where no other oil crops can grow and have less environmental impact, need to be developed. It is preferable that such new oil crops would allow us to tailor-make the oil composition in planta for food, fuel or industrial applications. In Sweden, the main oil crop cultivated is winter rapeseed, which, due to weak winter hardiness, only can be grown in southern Sweden. Developing a new winter-hardy oilseed crop would extend the plant oil production in Sweden and other cold climate regions. Lepidium campestre is a wild Brassica species. It is very winter hardy, high-yielding, has an upright stature and synchronous flowering. Moreover, it is biennial, and thus being suitable as a catch crop. However, it needs to be domesticated first so that it possesses all important agronomic traits necessary for being a successful agricultural crop. The aim of this thesis was to improve some properties of L. campestre by genetic engineering with focus on: the seed oil content, pod shatter, seed oil composition and wax ester production in the seed oil. In order to enable genetic engineering of this wild species, a well-functioning regeneration and transformation protocol was first developed, which has greatly facilitated the subsequent genetic improvements of the target traits of the species. Through RNAi-down-regulation of the FAD2 and FAE1 genes, transgenic lines with oxidative stable oil high in oleic acid were generated, indicating the potential of the species for being used for food oil purposes. Moreover, transgenic lines with increased seed oil content were developed by expressing either the AtWRI1 or AtHb2 or BvHb2 gene. Transgenic lines with pod shatter resistance were produced by RNAi down-regulation of the IND gene. Wax esters were produced in this species by expression of the jojoba wax synthesis genes, showing the potential of the species as a new platform for industrial oil production. These transgenic lines are valuable materials for further breeding of this species
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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