Controlling insect pests with bacterial genes.

Abstract available in text

Concurrent Suppression of Virus Replication and Rescue of Movement-Defective Virus in Transgenic Plants Expressing the Coat Protein of Potato Virus X

AbstractA line of transgenic tobacco expressing the coat protein (CP) of potato virus X (PVX) was resistant against a broad spectrum of PVX strains. Inoculation of leaves and protoplasts with PVX expressing the jellyfish green fluorescent protein reporter gene revealed that this resistance mechanism suppressed PVX replication in the initially infected cell and systemic spread of the virus. Cell-to-cell movement was also slower in the resistant plants. The resistance at the level of replication was effective against wild-type PVX and also against movement-defective isolates with a frameshift mutation or deletion in the CP ORF. However, the cell-to-cell movement defect of the mutant viruses was rescued on the resistant plants. Based on these results it is proposed that the primary resistance mechanism is at the level of replication

Theories of Learning and Curriculum Design: Key Positionalities and Their Ralationships

One of the challenges academics face when designing pedagogies and curricula is how best to articulate their own positionalities regarding the different ways theories or models of learning inform both the process of design as well as the product. It is difficult to find a text book or design resource that illustrates the relationships between the main theories of learning and how they might inform a coherent approach to programme design in higher education. For that reason we decided to produce this summative guide to learning theories and a chart illustrating their relevance for pedagogies and for curriculum design. The guide starts with our agreed glossary of terms which are used to structure both the text and the chart. We then briefly describe the five main models of learning used in the chart: behaviourist, humanist, information processing, activity and situated. We hope the reader will find the text and the chart useful in generating structured discussion when facing a major pedagogical or curriculum design task

An N-terminal Peptide Extension Results in Efficient Expression, but not Secretion, of a Synthetic Horseradish Peroxidase Gene in Transgenic Tobacco

BACKGROUND AND AIMS: Native horseradish (Armoracia rusticana) peroxidase, HRP (EC 1.11.1.7), isoenzyme C is synthesized with N-terminal and C-terminal peptide extensions, believed to be associated with protein targeting. This study aimed to explore the specific functions of these extensions, and to generate transgenic plants with expression patterns suitable for exploring the role of peroxidase in plant development and defence. METHODS: Transgenic Nicotiana tabacum (tobacco) plants expressing different versions of a synthetic horseradish peroxidase, HRP, isoenzyme C gene were constructed. The gene was engineered to include additional sequences coding for either the natural N-terminal or the C-terminal extension or both. These constructs were placed under the control of a constitutive promoter (CaMV-35S) or the tobacco RUBISCO-SSU light inducible promoter (SSU) and introduced into tobacco using Agrobacterium-mediated transformation. To study the effects of the N- and C-terminal extensions, the localization of recombinant peroxidase was determined using biochemical and molecular techniques. KEY RESULTS: Transgenic tobacco plants can exhibit a ten-fold increase in peroxidase activity compared with wild-type tobacco levels, and the majority of this activity is located in the symplast. The N-terminal extension is essential for the production of high levels of recombinant protein, while the C-terminal extension has little effect. Differences in levels of enzyme activity and recombinant protein are reflected in transcript levels. CONCLUSIONS: There is no evidence to support either preferential secretion or vacuolar targeting of recombinant peroxidase in this heterologous expression system. This leads us to question the postulated targeting roles of these peptide extensions. The N-terminal extension is essential for high level expression and appears to influence transcript stability or translational efficiency. Plants have been generated with greatly elevated cytosolic peroxidase activity, and smaller increases in apoplastic activity. These will be valuable for exploring the role of these enzymes in stress amelioration and plant development

A longitudinal study examining changes in street connectivity, land use, and density of dwellings and walking for transport in Brisbane, Australia

Background: Societies face the challenge of keeping people active as they age. Walkable neighborhoods have been associated with physical activity, but more rigorous analytical approaches are needed. Objectives: We used longitudinal data from adult residents of Brisbane, Australia (40–65 years of age at baseline) to estimate effects of changes in neighborhood characteristics over a 6-y period on the likelihood of walking for transport. Methods: Analyses included 2,789–9,747 How Areas Influence Health and Activity (HABITAT) cohort participants from 200 neighborhoods at baseline (2007) who completed up to three follow-up questionnaires (through 2013). Principal components analysis was used to derive a proxy measure of walkability preference. Environmental predictors were changes in street connectivity, residential density, and land use mix within a one-kilometer network buffer. Associations with any walking and minutes of walking were estimated using logistic and linear regression, including random effects models adjusted for time-varying confounders and a measure of walkability preference, and fixed effects models of changes in individuals to eliminate confounding by time-invariant characteristics. Results: Any walking for transport (vs. none) was increased in association with an increase in street connectivity (+10 intersections, fixed effects OR=1.19; 95% confidence interval (CI): 1.07, 1.32), residential density (+5 dwellings/hectare, OR=1.10; 95% CI: 1.05, 1.15), and land-use mix (10% increase, OR=1.12; 95% CI: 1.00, 1.26). Associations with minutes of walking were positive based on random effects models, but null for fixed effects models. The association between land-use mix and any walking appeared to be limited to participants in the highest tertile of increased street connectivity (fixed effects OR=1.17; 95% CI: 0.99, 1.35 for a 1-unit increase in land-use mix; interaction p-value=0.05). Conclusions: Increases in street connectivity, residential density, and land-use heterogeneity were associated with walking for transport among middle-age residents of Brisbane, Australia. https://doi.org/10.1289/EHP208

Homeologous Plastid DNA Transformation in Tobacco Is Mediated by Multiple Recombination Events

Efficient plastid transformation has been achieved in Nicotiana tabacum using cloned plastid DNA of Solanum nigrum carrying mutations conferring spectinomycin and streptomycin resistance. The use of the incompletely homologous (homeologous) Solanum plastid DNA as donor resulted in a Nicotiana plastid transformation frequency comparable with that of other experiments where completely homologous plastid DNA was introduced. Physical mapping and nucleotide sequence analysis of the targeted plastid DNA region in the transformants demonstrated efficient site-specific integration of the 7.8-kb Solanum plastid DNA and the exclusion of the vector DNA. The integration of the cloned Solanum plastid DNA into the Nicotiana plastid genome involved multiple recombination events as revealed by the presence of discontinuous tracts of Solanum-specific sequences that were interspersed between Nicotiana-specific markers. Marked position effects resulted in very frequent cointegration of the nonselected peripheral donor markers located adjacent to the vector DNA. Data presented here on the efficiency and features of homeologous plastid DNA recombination are consistent with the existence of an active RecA-mediated, but a diminished mismatch, recombination/repair system in higher-plant plastids

Tektonika : The Community-Led Diamond Open-Access Journal for Tectonics and Structural Geology

Acknowledgements First and foremost, we would like to thank the tectonics and structural geology community for embracing this initiative from the start. Their feedback, enthusiasm, and passion about DOA were essential to the launch of Tektonika. The success of Tektonika would not be possible without our Associate Editors, who volunteered their time to support the editorial process, the authors, who trusted us with their research, and the reviewers, who agreed to provide their invaluable peer-review. These three pillars of the publishing system made the publication of this first issue possible. We would like to thank the University of Aberdeen, especially the Department of Geology and Geophysics in the School of Geosciences, for supporting Tektonika financially and morally. We are also grateful to Volcanica and its team for leading the way and sharing with us their know-how to set up a community-led DOAJ. Fabian Wadsworth (Volcanica) and Stephen Hicks (Seismica) are thanked for reviewing this editorial and providing valuable feedback and comments.Peer reviewedPublisher PD

Transplastomic tobacco plants expressing a fatty acid desaturase gene exhibit altered fatty acid profiles and improved cold tolerance

The possibility of altering the unsaturation level of fatty acids in plant lipids by genetic transformation has implications for the stress tolerance of higher plants as well as for their nutritional value and industrial utilisation. While the integration and expression of transgenes in the plastome has several potential advantages over nuclear transformation, very few attempts have been made to manipulate fatty acid biosynthesis using plastid transformation. We produced transplastomic tobacco plants that express a Delta9 desaturase gene from either the wild potato species Solanum commersonii or the cyanobacterium Anacystis nidulans, using PEG-mediated DNA uptake by protoplasts. Incorporation of chloroplast antibioticinsensitive point mutations in the transforming DNA was used to select transformants. The presence of the transcript and the Delta9 desaturase protein in transplastomic plants was confirmed by northern and western blot analyses. In comparison with control plants, transplastomic plants showed altered fatty acid profiles and an increase in their unsaturation level both in leaves and seeds. The two transgenes produced comparable results. The results obtained demonstrate the feasibility of using plastid transformation to engineer lipid metabolic pathways in both vegetative and reproductive tissues and suggest an increase of cold tolerance in transplastomic plants showing altered leaf fatty acid profiles. This is the first example of transplastomic plants expressing an agronomically relevant gene produced with the ‘‘binding-type’’ vectors, which do not contain a heterologous marker gene. In fact, the transplastomic plants expressing the S. commersonii gene contain only plant-derived sequences, a clear attraction from a public acceptability perspective