24
EIGIL KJELDSEN and STEEN K0LVRAA
DNA (relative to the control) or equality of hybridization. The analysis is
performed by specialized software, which analyses images of the microarrays generated by a CCD camera coupled to a fluorescence type microscope.
New developments in probe types
PNA, LNA and padlock probes are new probe types in the FISH field which
hold great promise for quantitation and high specificity FISH.
Polypeptide nucleic acids
Polypeptide nucleic acid, PNA, is a synthetic DNA analogue in which the
deoxyribose-phosphate backbone is substituted with (2-aminoethyl)-glycine. PNA has the advantage of rapidly forming very stable duplexes with
complementary DNA. The neutral peptide backbone provides no electrostatic repulsion to the DNA-phosphate groups therefore favoring the rapid
kinetics of PNA-DNA duplex formation and a high thermal stability (Nielsen et al. 1991, Egholm et al. 1993).
Recently, a PNA oligomer was introduced as a FISH probe identifying
all 96 telomers in a human metaphase chromosome spread (Lansdorp et
al. 1996). The highly efficient hybridization property of the PNA probe
contributed to a better FISH stoichiometry, thereby providing a firm basis
for measuring relative lengths of telomeres on the basis of fluorescence
intensity by digital imaging microscopy. For other repeat sequences
such as centromere specific alphoid DNAs, the simple satellite DNAs
and Alu-repeats, PNA-FISH probes are currently being developed (Taneja
et al. 2001). The better FISH signal intensity and stoichiometry may in the
future allow low level repeat and perhaps even unique sequence detection
using this new DNA analogue.
locked nucleic acids
Locked nucleic acid, LNA, is a synthetic DNA analogue that is conformationally restricted containing 2'-O,4-C-methylene LNA nucleoside monomers (Kumar et al. 1998). LNA is capable of recognizing complementary
DNA and RNA with high thermal stability which, in the future, may allow
for a better FISH signal intensity.
EIGIL KJELDSEN and STEEN K0LVRAA
DNA (relative to the control) or equality of hybridization. The analysis is
performed by specialized software, which analyses images of the microarrays generated by a CCD camera coupled to a fluorescence type microscope.
New developments in probe types
PNA, LNA and padlock probes are new probe types in the FISH field which
hold great promise for quantitation and high specificity FISH.
Polypeptide nucleic acids
Polypeptide nucleic acid, PNA, is a synthetic DNA analogue in which the
deoxyribose-phosphate backbone is substituted with (2-aminoethyl)-glycine. PNA has the advantage of rapidly forming very stable duplexes with
complementary DNA. The neutral peptide backbone provides no electrostatic repulsion to the DNA-phosphate groups therefore favoring the rapid
kinetics of PNA-DNA duplex formation and a high thermal stability (Nielsen et al. 1991, Egholm et al. 1993).
Recently, a PNA oligomer was introduced as a FISH probe identifying
all 96 telomers in a human metaphase chromosome spread (Lansdorp et
al. 1996). The highly efficient hybridization property of the PNA probe
contributed to a better FISH stoichiometry, thereby providing a firm basis
for measuring relative lengths of telomeres on the basis of fluorescence
intensity by digital imaging microscopy. For other repeat sequences
such as centromere specific alphoid DNAs, the simple satellite DNAs
and Alu-repeats, PNA-FISH probes are currently being developed (Taneja
et al. 2001). The better FISH signal intensity and stoichiometry may in the
future allow low level repeat and perhaps even unique sequence detection
using this new DNA analogue.
locked nucleic acids
Locked nucleic acid, LNA, is a synthetic DNA analogue that is conformationally restricted containing 2'-O,4-C-methylene LNA nucleoside monomers (Kumar et al. 1998). LNA is capable of recognizing complementary
DNA and RNA with high thermal stability which, in the future, may allow
for a better FISH signal intensity.