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Biomedical subjects

Philippe Vain

Publications and source records attributed to Philippe Vain.

5 recordsLinked to original sources
PubMed2006

Global trends in plant transgenic science and technology (1973-2003).

Transgenic science and technology are fundamental to state-of-the-art plant molecular genetics and GM crop improvement. Monitoring the scale and growth of this area of science is important to scientists, national and international research organizations, funding bodies, policy makers and, because of the GM debate, to society as a whole. Literature statistics covering the past 30 years reveal a dramatic increase in plant transgenic science in Asia during the past decade, a sustained expansion in North America and, recently, a slow down in the rest of the world. With the exception of the output of China and India, publications focusing on the development of transgenic technology have been slowing down, worldwide, since the early mid-1990s, a trend that contrasts with the increase in GM crop-related studies.

Agriculture↗
PubMed2004

Strategies for precise quantification of transgene expression levels over several generations in rice.

Variation in transgene expression levels can result from uncontrolled differences in experimental protocols. Studies conducted over generations could, by their design, generate additional unwanted variation. To study sources of spurious variation, transgene expression levels were quantified over five homozygous generations in two independent transgenic rice lines created by particle bombardment. Both lines contained the same gus expression unit and had been shown to exhibit stable inheritance of transgene structure and expression. All plants were cultured and sampled using previously developed standardized protocols. Plants representative of each generation (T2, T3, T4, T5, T6) were grown either all together or across several different growth periods. GUS activity in plants from different generations was quantified either in the same assay or over multiple independent assays. Strategies in which plants were grown and phenotyped independently, significantly increased (up to 3-fold) extraneous variation in transgene expression level quantification, thus reducing the precision of molecular genetic studies and generating artefactual results in transgenic studies conducted over generations. Identification of sources of unwanted variation and quantification of their effect allowed the development of new strategies designed to control spurious variation. Growth and phenotyping of all plants from all generations together, using standard operating procedures (SOP), led to a reduction in extraneous variation associated with transgene expression level quantification. Adoption of such strategies is key to improving the reproducibility of transgenic studies conducted over generations.

Gene Expression Regulation, Plant↗
PubMed2004

The effect of additional virulence genes on transformation efficiency, transgene integration and expression in rice plants using the pGreen/pSoup dual binary vector system.

We assessed the effect of four different virulence (vir) gene combinations on plant transformation efficiency and transgene behaviour in rice using the pGreen/pSoup dual binary vector system. Transformation experiments were conducted using a pGreen vector containing the bar and gusA expression units with, or without, the virG542, virGN54D, virGwt or the virG/B/C genes added to the backbone. Additonal vir gene(s) significantly altered plant transformation efficiency and the integration of vector backbone sequences. However, no differences in transgene copy number, percentage of expressing lines and expression levels could be detected. Addition of virGwt was the most beneficial, doubling the overall performance of the pGreen/pSoup vector system based on transformation frequency, absence of backbone sequence integration and expression of unselected transgenes. In 39% of the plant lines, the additional vir genes were integrated into the rice genome. The contribution of 'super dual binary' pGreen/pSoup vectors to the development of efficient rice transformation systems and to the production of plants free of selectable marker genes are discussed.

Gene Expression↗
PubMed2004

Development of a standard operating procedure (SOP) for the precise quantification of transgene expression levels in rice plants.

Variation in transgene expression levels can result from uncontrolled differences in experimental protocols. It is important to quantify and eliminate this unwanted variation as much as possible in order to attain precision in transgenic studies. Large-scale transgenic studies could, by their design, generate additional variation. The influence of different plant growth, sampling and analysis strategies in generating spurious variation in transgene expression level quantification in rice plant populations was assessed. The use of multiple independent plant phenotypic analyses (enzymatic assays in this study) was identified as the major source of spurious variation (doubling or tripling the variation). The quantification of transgene expression levels was also found to be significantly influenced by plant age, the choice of leaf sampled and leaf size. All of these factors reduced the precision of molecular genetic studies and generated artefactual results in transgenic studies. Identification of the sources of extraneous variation allowed the development of a new standard operating procedure (SOP) for rice, designed to control spurious variation. SOP allowed the influence of differences in growth period and independent phenotypic analyses to be minimized. The coefficient of variation in transgene expression levels, between and within genetically identical rice plants, was reduced to approximately 10 to 15% using SOP. Adoption of quality assurance (QA) criteria such as SOP is key to improving the reproducibility of transgenic studies.

Journal Article↗