Transcriptomics analysis of phloem-feeding insect resistance in rice germplasm

The Brown Plant Hopper (BPH) is a serious pest of rice in Asia. Development of novel control strategies can be facilitated by a comparison of BPH feeding behaviour on varieties exhibiting natural genetic variation, and then an elucidation of the underlying mechanisms of resistance. We began by understanding BPH feeding behaviour on 12 rice varieties with different resistance background using Electrical Penetration Graph (EPG) and honeydew clock experiments. Seven feeding behaviours (waveforms) were identified and could be classified into two phases, feeding and non- feeding. Cluster analysis has separated the 12 varieties into 3 main groups, resistant, moderate and susceptible. Then, we undertook microarray analysis on all varieties to identify candidate genes which may contribute to resistance. The results reveal the difference between resistant and susceptible varieties. The data agree with EPG and honeydew clock experiments. A total of 21556 probes passed filter in statistical analysis using quantile method (in Genespring) and 239 probes significantly contributed to the difference between resistant versus susceptible (Volcano analysis). Some of them were found to be highly correlated with EPG data and could therefore be potential resistance candidate genes against BPH such as gene encoding hexose transporter, protein kinases, Alpha-DOX2 and peroxidase

The management of cognitive resources

It is argued that an understanding of complex cognitive performance can best be achieved by considering both processing and representational cognitive resources. In any given task, control processes are important for configuring such resources appropriately and passing information between them. A computer controlled alphabet counting task which allows storage and processing requirements to be independently manipulated is used to gain a better understanding of the organisation and utilisation of resources by providing access to the microstructure of performance. Three main directions are explored. The first establishes baseline conditions for varying parameters of the task. Most notably, it demonstrates that resources are typically set up for the expected task difficulty prior to the task commencing, rather than as a consequence of immediate task demands. The second theme explores individual differences in carrying out one of the more complex conditions of the task, and shows that subgroups of subjects can be isolated who exhibit distinct patterns of performance. Moreover, in a task of this complexity, gross predictors of individual differences, such as IQ, do not relate to overall performance in any simple way, although they can be understood within each subgroup. The third group of experiments explore sensitivity to stressors external to the immediate task. Two 'environmental stressors' (alcohol and noise) and one 'cognitive stressor' (an additional concurrent memory load) are examined. Reliable differential effects are observed on the storage and processing phases of the task within individual subjects, but variations in the precise pattern of effects between subjects result in group data being potentially misleading. Finally, the requirements for an appropriate framework which can capture the most important aspects of resource management are considered, and a framework incorporating components of contemporary models of working memory is presented