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Two PhD positions

Arjen Schots arjen.schots at LMA.NEMA.WAU.NL
Thu Aug 20 16:18:28 EST 1998

Within the Laboratory of Biochemistry, Department of Biomolecular Sciences
and the Laboratory for Monoclonal Antibodies, Department of Plant Sciences
of the Wageningen Agricultural University TWO PhD positions are available
in a project entitled: Development of multimode fluorescence correlation
microscopy suitable for high throughput screening and applications in plant
signal transduction research. This project is subsidised by the Technology
Foundation and coordinated by the Council of the Geosphere and Biosphere
sciences of the National research Council (reference nr.

Task description:
The central objective is the development of a real multimode fluorescence
correlation microscope (FCM). Implementation of novel technological
developments in opto-electronics, accurate sample positioning,
piezo-mechanical focussing at successive depths in the sample and insertion
of multiple excitation and detection ports results in a confocal microscope
which combines different modalities: (cross-) correlation spectroscopy
diffusion mapping of fluorescent molecules, measurement of concentrations
and interactions), quantitative time-lapse digital image microscopy
(tracking fluorescent molecules in cells during their life cycle),
three-dimensional image reconstruction (3D images of microscopic objects)
and spectral imaging microscopy (to characterise emission spectra of
microscopic objects).
One application of FCM in (bio)technology is the use as a device to screen
large numbers of samples. Present advances in biotechnology, biomedicine
and chemistry require equipment to screen large numbers of samples both
accurately and rapidly, particularly in those situations where biomolecular
interactions are studied. FCM allows the screening of such interactions in
minute (submicroliter) volumes using "single molecule" sensitivity. We will
investigate this by screening antibodies, genetically fused to the green
fluorescent protein (GFP) of the jelly fish Aequorea victoria, arising from
selections of large antibody phage display libraries for binding
A second application involves the use of the FCM as a research instrument
in biology. We will investigate this by studying some molecular events in
the sedentary nematode - plant interaction. Sedentary nematodes are
endoparasites inducing feeding cells in the roots of host plants on which
they fully rely to complete their life cycle. We have chosen to use this
model system because one of the morphological characteristics of these
cells is the lack of a central vacuole allowing detailed studies on
processes in and around the nucleus. A typical feature of this intimate
relationship is the triggering of the cell cycle in nematode feeding cells,
which never show cell division. Using GFP under control of cell cycle
promoters we will measure the buildup and trafficking of this protein. By
fusing a red fluorescent and wild type GFP to, respectively, the cell cycle
proteins cyclAt (a cyclin) and a cdc2a (a cyclin dependent) kinase we will
study their interaction. In a next step the kinase activity of cdc2a will
be investigated using a fluorescent substrate. In a final stage we will
study the activity of auxin. This plant hormone is one of the key
regulators of plant growth and development and as such affects the cell
cycle. We recently obtained evidence that this is also true for nematode
feeding cell development. Fluorescent auxin analogues will be used to
investigate where and how it binds to cells and when the cell cycle is
entered as a consequence of this action.

The first PhD student will construct the multimode FCM starting from an
existing fluorescence correlation system. Using FCS a high throughput
screening system will be developed as described above. Two sampling
principles will be developed. The first one is based on 96 (or 384) well
plates and the second one is based on a continuous flow system using
Required: University degree in (bio)physics, (bio)physical chemistry or
molecular sciences. Fluent in English. Experience with fluorescence
microscopy and image analysis is a preference.
The second PhD student will use FCM as a research instrument in biology
focusing on the nematode-plant interaction as described above.
Required: University degree in biology or molecular sciences. Fluent in
English. Experience with molecular biological or cell biological techniques
is a preference.

Both PhD students will be supported by a technician.

Information can be obtained by:
Dr. A. Visser. Tel. Nr. +31-317-482862 e-mail: Ton.Visser at laser.bc.wau.nl
Dr. A. Schots Tel. Nr. +31=317-485261 e-mail: Arjen.Schots at lma.nema.wau.nl

To apply for one of the above positionsplease send your curriculum vitae to
Dr. A. Visser, Microspectroscopy Center, Laboratory of Biochemistry,
Department of Biomolecular Sciences, Wageningen Agricultural University,
Dreijenlaan 3, 6703 HA Wageningen. Or e-mail it to
Ton.Visser at laser.bc.wau.nl

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