Epidemiology and management of rice tungro disease

Since the mid 1960s, rice tungro virus disease has had a serious economic impact on rice production in South-East Asia. Although the frequency and intensity of outbreaks have declined since their peak in the late 1960s and early 1970s, occasional major epidemics do sill occur, often associated with changes in agronomic practices. Epidemiology and Management of Rice Tungro Disease is the outcome of a workshop held in Malaysia where researchers including representatives from five major rice producing countries met to discuss the present status of the disease and the progress of research into its management. The publication outlines current options for integrated management of tungro and critically reassesses vector control strategies. The book will be of interest to scientists and officials from national agricultural departments who have to make decisions on the management of this important disease

The ecology of tropical plant viruses

In recent decades ecology has become one of the dominant themes of the biological sciences. However, this has not always been so as the subject emerged from the specialist study of plant and animal communities in natural habitats that were often remote and sometimes exotic. It has since become a unifying all-embracing discipline that is of great importance, not only in botany, zoology and microbiology, but also in international affairs in relation to current issues concerning the environment, conservation, pollution, sustainability and the constraints to the growth of human populations and economies. The current prominence and status of ecology is reflected in the series of Inaugural Lectures of which this is a part. It is concerned with the ecology of tropical plant viruses and Professor Cheke also adopted an ecological approach in his presentation on river blindness. Moreover, Professor Grant dealt with eco-toxicology and Professor Hall has adopted the title of Professor of Chemical Ecology. My presentation is in four parts. A brief section on the history of tropical plant virology and the prominent role that has been and continues to be played by UK scientists is followed by general comments on tropical environments, crops, viruses and vectors. Six important virus diseases are then considered in some detail as a basis for a more general discussion of some of the main issues raised

Progress in cassava technology transfer in Uganda

This publication contains the full text of papers presented at a Workshop held in Masindi, Uganda, 9-12 January 1996, and sponsored by the Gatsby Charitable Foundation. During the Workshop the need became evident for additional statistics on the multiplication, distribution and uptake of improved varieties of cassava in the six districts where activities are supported by The Gatsby Charitable Foundation and also elsewhere. The results of a subsequent survey in selected sub-counties of each of the six Gatsby districts are also presented here, together with estimates of the amount of improved material that has been distributed and the area now grown. These latest figures (Appendix 1) represent the best available estimates and in some instances differ substantially from those compiled and presented in the earlier district reports

Structural analysis of DNA binding by C.Csp231I, a member of a novel class of R-M controller proteins regulating gene expression

In a wide variety of bacterial restriction–modification systems, a regulatory `controller' protein (or C-protein) is required for effective transcription of its own gene and for transcription of the endonuclease gene found on the same operon. We have recently turned our attention to a new class of controller proteins (exemplified by C.Csp231I) that have quite novel features, including a much larger DNA-binding site with an 18 bp (∼60 Å) spacer between the two palindromic DNA-binding sequences and a very different recognition sequence from the canonical GACT/AGTC. Using X-ray crystallography, the structure of the protein in complex with its 21 bp DNA-recognition sequence was solved to 1.8 Å resolution, and the molecular basis of sequence recognition in this class of proteins was elucidated. An unusual aspect of the promoter sequence is the extended spacer between the dimer binding sites, suggesting a novel interaction between the two C-protein dimers when bound to both recognition sites correctly spaced on the DNA. A U-bend model is proposed for this tetrameric complex, based on the results of gel-mobility assays, hydrodynamic analysis and the observation of key contacts at the interface between dimers in the crystal.</jats:p

Characterization of brown streak virus-resistant cassava

Cassava brown streak disease (CBSD) has become a major constraint to cassava production in East and Central Africa. The identification of new sources of CBSD resistance is essential to deploy CBSD mitigation strategies as the disease is progressing westwards to new geographical areas. A stringent infection method based on top cleft grafting combined with precise virus titer quantitation was utilized to screen fourteen cassava cultivars and elite breeding lines. When inoculated with mixed infections of Cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV), the scions of elite breeding lines KBH 2006/18 and KBH 2006/26 remained symptom-free during a 16-week period of virus graft inoculation, while susceptible varieties displayed typical CBSD infection symptoms at 4 weeks after grafting. The identified CBSD resistance was stable under the co-inoculation of CBSV, UCBSV with cassava geminiviruses (CGMs). Double grafting experiments revealed that transmission of CBSV and UCBSV to CBSD susceptible top scions was delayed when using intermediate scions of elite breeding lines KBH 2006/18 and KBH 2006/26. Nonetheless, comparison of virus systemic movement using scions from KBH2006/18 and a transgenic CBSD resistant 60444 line (60444-Hp9 line) showed that both CBSV and UCBSV move at undetectable levels through the stems. Further, protoplast-based assays of virus titers over time showed that the replication of CBSVs is inhibited in the resistant line KBH2006/18, suggesting that the identified CBSD resistance is at least partially based on inhibition of virus replication. Our molecular characterization of CBSD resistance in cassava offers a robust virus–host system to further investigate the molecular determinants of CBSD resistance

Adapted Primary Literature (APL): An Effective Authentic Text Option for the Science Classroom

The intention of this literature review is to advocate for the incorporation of Adapted Primary Literature (APL) into secondary science classroom instruction in order to aid such science curriculum in achieving balanced authenticity. APL is a valuable instructional text option due to its novel design, an optimal compromise between authenticity and accessibility. APL is a superior reflection of authentic science as it is for professionals of science and in representation of the nature of science (NOS) than Secondary Literature (SL) and textbooks, the dominating scientific text genres of most secondary science classroom instruction. Yet, APL is more accessible in text sophistication and structure than arguably the most authentic genre, Primary Scientific Literature (PSL). In other words, due to such negotiated design, APL could prove invaluable at addressing a multitude of science education objectives associated with authenticity, such as those pertaining to the following common categorical headings: literacy, argumentation, inquiry, concept competence, and the nature of science, to name a few. In addition, APL may address the contemporary science education goals of increased student interest, motivation, and pursuit of scientific endeavors. After all, the current and likely future direction of the global economy, professional atmosphere, consumer decision-making, technological advancements, and environmental threats has required that science education be concerned with far more than just student memorization of content within an isolated, singular disciplinary year. Suggested remedies for potential incorporation challenges, areas in need of further research, and common contrary research positions will be included to provide a comprehensive and supportive examination of APL implementation. No instructive technique is without tradeoffs. Like any other educative method, the success of APL implementation is greatly influenced by the quality of surrounding instruction. Possessing scientific authenticity “in some defined way is never sufficient justification by itself for engaging in an educational practice. Authenticity is no guarantee of effectiveness” (Norris et al., 2009, p. 407)