DIGITAL IMAGE PROCESSING FOR
FLUORESCENCE IN-SITU HYBRIDIZATION
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human DNA Repeats SV40 pig nuclear-transfert rat QFISH mouse Southern-blot Cercomona mona CGA-project Bovin aging Linux interstitial telomeric sequences Image processing MFISH Heteromorphism karyotyping immortalization Cebus capucinus resume |
Thesis, presentations | Southern
blot tools |
QFISH
tool |
Proposals, papers and unpublished stuff |
The
telomeres: some words
The number of divisions that most
of normal human cells is limited in-vitro.
This limit is due to the extremities of the linear structure of the
chromosomes found in all the eucaryotic cells, called the telomeres.
The telomeres are nucleo-proteic complexes located at the very end of
the eucaryotic chromosomes. In each cell, the DNA sequence of each of
the 92 human telomeres is composed of hundreds to thousands repetition
of a six nucleotidic base pairs TTAGGG.These motifs are recognized by
specific proteins that ensure the cellular stability of the
chromosomes. Due to the mechanisms of DNA replication, the replication
of the telomeres is incomplete leading to a progressive loss of TTAGGG
DNA motifs in absence of a specialized enzyme : the telomerase.
In human tissues, the telomerase is only expressed in a subset of
normal cells at variable rates which do not always compensate the
telomere shortening, the telomerase is constituvely expressed in most
cancer cells. The limit of proliferatif potential of the normal cells
might weight on the human longevity but also imposes constraints to the
in-vitro cellular cultures. Thus the telomere length is an indicated
tool to predict the proliferative capacities of cells, which had direct
applications in cell therapies, cloning technologies. |
Different kind of ressources regarding the biology of the telomeres are available on this site. Software to compute telomere length can be downloaded: QuantFISHmacros are a set of macro written for NIH-Image/SCION-Image to measure fluorescent FISH signals (telomeres, ....). My thesis, several presentations (some about quantitative imaging using fluorescent microscopy) as well as projects (AFM,CEA). |
Candidating at CEA | Imaging_CEA_2002.pdf Speech_candidature_CEA_2002.pdf |
Thesis: Dynamique de la longueur des telomeres au cours de la senescence et de l'immortalisation de cellules humaines. |
thesis_telomeres.pdf Speech_thesis.pdf |
DESS de biologie et de
pharmacologie du vieillissement In this report written in 1994, early results on intracellular telomeric heterogeneity. |
DESS_telomeres_1994.pdf |
Jussieu 2001 | |
INRA 2001 |
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Neurotech 2000 |
Tools for measuring the telomere length by Southern-blotting
Those tools have to be used after densitometric extraction of the telomeric smears (using NIH-Image for example). They consist in a serie of short programs (macro written in a pascal like language) for Pro-Fit 5.01 a scientific application for non-linear curve-fitting developped by quansoft. |
Tools for
Quantitative FISH |
QuantFISH: QuantFISH is a set of macro for NIH-Image (compatible with SCION-Image) running under MacOS (9.x , MacOS X not tested). The aim of QuantFISH is to accelerate the extraction of measurements of fluorescent signals on metaphasic chromosomes (such telomeres) by the extensive use of keyboards shortcuts. These macro were written to work on 12 bits TIFF images recorded on a windows/intel computer (bit depth 4096 , size 1536x1024, little endian). However the source code can be easily modified to work on any kind of TIFF image. |
QFISH_macros_V1.1
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CGA project CytoGenetic Assistant is a software primilarly dedicaced to quantitavive analysis of telomeric signals on metaphasic chromosomes. CGA has been developped byADCIS , those people do make a great job. CGA 3.1.x marks a large evolution over the previous version with new modules (flatfield correction, batch processing, SQL to build chromosomes gallery, new segmentation algorithms, preview systems), an impressive evolution of the system consists in the capability to fully customize the GUI and message passing between modules. Chromosomal preparation were observed by fluorescence using alphavivid filters set by omegafilters, the image were recorded with a slow scan CCD camera (Lhésa, KAF1600).
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