1,286 research outputs found

    Crop biotechnology: prospects and opportunities

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    Sequence analysis of the cupin gene family in Synechocystis PCC6803

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    The recently described cupin superfamily of proteins includes the germin and germinlike proteins, of which the cereal oxalate oxidase is the best characterized. This superfamily also includes seed storage proteins, in addition to several microbial enzymes and proteins with unknown function. All these proteins are characterized by the conservation of two central motifs, usually containing two or three histidine residues presumed to be involved with metal binding in the catalytic active site. The present study on the coding regions of Synechocystis PCC6803 identifies a previously unknown group of 12 related cupins, each containing the characteristic two-motif signature. This group comprises 11 single-domain proteins, ranging in length from 104 to 289 residues, and includes two phosphomannose isomerases and two epimerases involved in cell wall synthesis, a member of the pirin group of nuclear proteins, a possible transcriptional regulator, and a close relative-of a cytochrome c551 from Rhodococcus. Additionally, there is a duplicated, two-domain protein that has close similarity to an oxalate decarboxylase from the fungus Collybia velutipes and that is a putative progenitor of the storage proteins of land plants

    Gene duplication and an accelerated evolutionary rate in 11S globulin genes are associated with higher protein synthesis in dicots as compared to monocots

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    Background: Seed storage proteins are a major source of dietary protein, and the content of such proteins determines both the quantity and quality of crop yield. Significantly, examination of the protein content in the seeds of crop plants shows a distinct difference between monocots and dicots. Thus, it is expected that there are different evolutionary patterns in the genes underlying protein synthesis in the seeds of these two groups of plants. Results: Gene duplication, evolutionary rate and positive selection of a major gene family of seed storage proteins (the 11S globulin genes), were compared in dicots and monocots. The results, obtained from five species in each group, show more gene duplications, a higher evolutionary rate and positive selections of this gene family in dicots, which are rich in 11S globulins, but not in the monocots. Conclusion: Our findings provide evidence to support the suggestion that gene duplication and an accelerated evolutionary rate may be associated with higher protein synthesis in dicots as compared to monocots

    Germin and germin-like proteins: evolution, structure, and function

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    Germin and germin-like proteins (GLPs) are encoded by a family of genes found in all plants. They are part of the cupin superfamily of biochemically diverse proteins, a superfamily that has a conserved tertiary structure, though with limited similarity in primary sequence. The subgroups of GLPs have different enzyme functions that include the two hydrogen peroxide-generating enzymes, oxalate oxidase (OxO) and superoxide dismutase. This review summarizes the sequence and structural details of GLPs and also discusses their evolutionary progression, particularly their amplification in gene number during the evolution of the land plants. In terms of function, the GLPs are known to be differentially expressed during specific periods of plant growth and development, a pattern of evolutionary subfunctionalization. They are also implicated in the response of plants to biotic (viruses, bacteria, mycorrhizae, fungi, insects, nematodes, and parasitic plants) and abiotic (salt, heat/cold, drought, nutrient, and metal) stress. Most detailed data come from studies of fungal pathogenesis in cereals. This involvement with the protection of plants from environmental stress of various types has led to numerous plant breeding studies that have found links between GLPs and QTLs for disease and stress resistance. In addition the OxO enzyme has considerable commercial significance, based principally on its use in the medical diagnosis of oxalate concentration in plasma and urine. Finally, this review provides information on the nutritional importance of these proteins in the human diet, as several members are known to be allergenic, a feature related to their thermal stability and evolutionary connection to the seed storage proteins, also members of the cupin superfamily

    Merit, Motivation, and Mythology

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    What are the most important motivating factors for educators? Are a series of popular myths clouding our analysis of what we can do to encourage effective teachers

    We make fiction because we are fiction : authorities displaced in the novels of Russell Hoban

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    Russell Hoban, born in Pennsylvania in 1925, is the author of fifty children's books and eight novels. This thesis provides a critical reading of his novels Kleinzeit (1974), The Medusa Frequency (1987), Riddley Walker (1980) and Pilgermann (1983). The thesis argues that the alienation of the protagonist from his society -- a theme common to the novels above -- is the result of the operation of the Derridean process of displacement. Hoban's novels work deconstructively to undermine binary oppositions (such as "reality" versus "fantasy"). I argue that the novels aim to recuperate the marginal by displacing the centre. In Kleinzeit and The Medusa Frequency, reality itself is figured as an absent centre. Through a discussion of magical realism, I show how Hoban questions the idea of a "consensus reality". I argue that by denying authority to the authors in these texts, Hoban privileges the uncertain authority of language itself. Using Derrida's concept of différance, I show that language in Kleinzeit is figured as an endless deferral of meaning. In Chapter II, I turn to an analysis of the invented post-atomic language of Riddley Walker, and examine how the neologisms and futuristic orthography of the text contribute towards significant wordplay. I argue that Riddley's attempts to read his culture's past offer a critique of the contemporary reader's assumptions, both about her present and about reading itself. I rely on Mircea Eliade's The Myth of the Eternal Return (1965) in discussing the nature of myth-making in Riddley Walker. In the final chapter, I discuss in detail the mechanism of displacement in Pilgermann. By examining the role of the grotesque in the novel, I argue that Pilgermann can be read hymeneutically. Derrida's figure of the hymen becomes the emblem of marginalisation. Using the example of the mode of the grotesque {which is prominent in the novel), I argue that the marginal is always already present in the very centre which would expel it. Pilgermann is read as an attempt to recuperate the margin in spite of "the confusion between the present and the non-present" (Derrida, 1984: 212) which is the hymen. Finally, I conclude that Hoban's works, while focussing on displacement, unwittingly displace women, by figuring them as absences whose existence is primarily metaphorical

    Global transcriptome analysis and identification of differentially expressed genes after infection of Fragaria vesca with powdery mildew (Podosphaera aphanis)

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    Background: Podosphaera aphanis, the causal agent of strawberry powdery mildew causes significant economic loss worldwide. Methods: We used the diploid strawberry species Fragaria vesca as a model to study plant pathogen interactions. RNA-seq was employed to generate a transcriptome dataset from two accessions, F. vesca ssp. vesca Hawaii 4 (HW) and F. vesca f. semperflorens Yellow Wonder 5AF7 (YW) at 1 d (1 DAI) and 8 d (8 DAI) after infection. Results: Of the total reads identified about 999 million (92%) mapped to the F. vesca genome. These transcripts were derived from a total of 23,470 and 23,464 genes in HW and YW, respectively from the three time points (control, 1 and 8 DAI). Analysis identified 1,567, 1,846 and 1,145 up-regulated genes between control and 1 DAI, control and 8 DAI, and 1 and 8 DAI, respectively in HW. Similarly, 1,336, 1,619 and 968 genes were up-regulated in YW. Also 646, 1,098 and 624 down-regulated genes were identified in HW, while 571, 754 and 627 genes were down-regulated in YW between all three time points, respectively. Conclusion: Investigation of differentially expressed genes (log2 fold changes �5) between control and 1 DAI in both HW and YW identified a large number of genes related to secondary metabolism, signal transduction; transcriptional regulation and disease resistance were highly expressed. These included flavonoid 3´-monooxygenase, peroxidase 15, glucan endo-1,3-β-glucosidase 2, receptor-like kinases, transcription factors, germin-like proteins, F-box proteins, NB-ARC and NBS-LRR proteins. This is the first application of RNA-seq to any pathogen interaction in strawberr
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