Predicting Gene Function from Uncontrolled Expression Variation among Individual Wild-Type Arabidopsis Plants

Gene expression profiling studies are usually performed on pooled samples grown under tightly controlled experimental conditions to suppress variability among individuals and increase experimental reproducibility. In addition, to mask unwanted residual effects, the samples are often subjected to relatively harsh treatments that are unrealistic in a natural context. Here, we show that expression variations among individual wild-type Arabidopsis thaliana plants grown under the same macroscopic growth conditions contain as much information on the underlying gene network structure as expression profiles of pooled plant samples under controlled experimental perturbations. We advocate the use of subtle uncontrolled variations in gene expression between individuals to uncover functional links between genes and unravel regulatory influences. As a case study, we use this approach to identify ILL6 as a new regulatory component of the jasmonate response pathway.     

Yeast RAS2 affects cell viability,mitotic division and transient gene expression in Nicotiana species

Overexpression of the budding yeast RAS2 gene in Nicotiana plumbaginifolia cells revealed that RAS2 acted as a suicide gene in freshly isolated protoplasts from leaves and blocked cell proliferation in cell suspension-derived protoplasts. Among a series of genes tested (such as npt II, CDC35, PDE2), RAS2 was the only one to block the expression of the cat gene, as measured in a transient gene expression assay. Another ras gene, v-Ha-ras, had similar effects. Furthermore, the RAS2 effect was species-specific and depended on the modulation of hormonal metabolism in the transfected cells, while no differences were noticed between the normal and the activated val19 gene. Transfected plant cells are shown to synthesize a RAS2 protein of the same electrophoretic mobility as the yeast RAS2 product. The results are discussed in the broader context of the evolutionarily conserved ras genes involved in vital cellular functions.     

Idiopathic Parkinsonism Treated with an Extracerebral Decarboxylase Inhibitor in Combination with Levodopa

The clinical actions of levodopa in Parkinsonism, given with and without an extracerebral decarboxylase in hibitor, L-alpha-methyldopahydrazine, were compared. Twenty-one patients were investigated in a “double-blind cross-over” study, administering levodopa in maximum tolerated dosage. L-Alpha-methyldopahydrazine failed to augment the overall therapeutic actions of levodopa but it consistently alleviated nausea. It is concluded that L-alpha-methyldopahydrazine will prove useful in the management of some Parkinsonian patients who have difficulty in taking levodopa alone.     

Community participation for malaria elimination in Tafea Province, Vanuatu: Part I. Maintaining motivation for prevention practices in the context of disappearing disease

Background

In Uganda, long-lasting insecticidal nets (LLIN) have been predominantly delivered through two public sector channels: targeted campaigns or routine antenatal care (ANC) services. Their combination in a mixed-model strategy is being advocated to quickly increase LLIN coverage and maintain it over time, but there is little evidence on the efficiency of each system. This study evaluated the two delivery channels regarding LLIN retention and use, and estimated the associated costs, to contribute towards the evidence-base on LLIN delivery channels in Uganda.

Methods

Household surveys were conducted 5-7 months after LLIN distribution, combining questionnaires with visual verification of LLIN presence. Focus groups and interviews were conducted to further investigate determinants of LLIN retention and use. Campaign distribution was evaluated in Jinja and Adjumani while ANC distribution was evaluated only in the latter district. Costs were calculated from the provider perspective through retrospective analysis of expenditure data, and effects were estimated as cost per LLIN delivered and cost per treated-net-year (TNY). These effects were calculated for the total number of LLINs delivered and for those retained and used.

Results

After 5-7 months, over 90% of LLINs were still owned by recipients, and between 74% (Jinja) and 99% (ANC Adjumani) were being used. Costing results showed that delivery was cheapest for the campaign in Jinja and highest for the ANC channel, with economic delivery cost per net retained and used of USD 1.10 and USD 2.31, respectively. Financial delivery costs for the two channels were similar in the same location, USD 1.04 for campaign or USD 1.07 for ANC delivery in Adjumani, but differed between locations (USD 0.67 for campaign delivery in Jinja). Economic cost for ANC distribution were considerably higher (USD 2.27) compared to campaign costs (USD 1.23) in Adjumani.

Conclusions

Targeted campaigns and routine ANC services can both achieve high LLIN retention and use among the target population. The comparatively higher economic cost of delivery through ANC facilities was at least partially due to the relatively short time this system had been in existence. Further studies comparing the cost of well-established ANC delivery with LLIN campaigns and other delivery channels are thus encouraged.     

Cloned sequence repertoires for small- and large-scale biology

How to assign function to the tens of thousands of genes discovered in the chromosomes of a few model species? How to complement the classical genetic approaches that are not always ideally suited to decode complex mechanisms? The solutions to these pressing questions are not simple and rely on the development of novel resources and technologies. Here I critically review what clone collections are available and how they can be exploited for the systematic analysis of gene functions in plants.