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Molecular biology of Trichoderma and biotechnological applications
No full textTrichoderma spp. comprise common soil Hyphomycetes found in all climate zones ranging from Antarctica to the tropics (Domsch et al. 1980). Characteristic of the genus Trichoderma is the ability to effectively degrade a range of natural polymers, especially cellulose and hemicellulose, which also provides foundation for the commercial uses of Trichoderma. The taxonomy of the genus Trichoderma has been and still is under some dispute, however, the basis being on the work of Rifai (1969) assigning the Trichoderma strains to nine species aggregates differentiated primarily by patterns of conidiophore branching and conidium morphology. Recent studies have used DNA fingerprinting, restriction fragment length polymorphism and amplification, and ITS sequencing to further clarify the taxonomy of Trichoderma (revieved in Gams and Bissett 1998; Lieckfeldt et al. 1998). This analysis has revealed that the industrially most relevant species, Trichoderma reesei, is an anamorph of the species Hypocrea jecorina. A genetically well-defined lineage of strains originating from the isolate QM6a was classified as T. reesei and all current biotechnologically relevant strains are derivatives of QM6a (see Nevalainen et al. 1994), which is a unique situation
Application of genetic engineering for strain improvement in filamentous fungi
No full textInherent characteristics of filamentous fungi such as the ability to grow on cheap cultivation media and excellent protein secretion makes them competitive production organisms when compared to the eukaryotic yeast, animal, plant, and insect cell systems. One of the principal aims in fungal strain improvement discussed in this Chapter is yield enhancement of a particular protein that is secreted into the cultivation medium. Early strain development programs were based on the application of random mutagenesis and screening of the mutagenized cells for specific characteristics (Rowlands 1984). This method has been particularly successful in the isolation of high protein-secreting mutant strains that are currently being used as expression hosts for both homologous and heterologous gene products (DunnColeman et al. 1991; Nevalainen et al. 1994a; Mäntylä et al. 1998). Currently, molecular techniques such as increasing the gene copy numbers as well as performing gene knockouts are being applied for the further refinement of fungal products and production systems [e.g., Mäntylä et al. (1998)]. A number of research programs discussed in this Chapter and elsewhere in this volume, have been initiated in order to better understand the complex genetic networks involved in gene expression and protein secretion in filamentous fungi
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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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