FISH Flashcards
FISH uses ___ light
excitation
A cytogenetic technique that uses fluorescent probes that bind specifically to a part of chromosomes complimentary to its sequence
FISH
Small strips of single stranded DNA complimentary to the sites we want to examine
Probes
Probes are ___ (natural/artificial) DNA
artificial
Target chromosomes are ___ (natural/artificial) DNA
natural
Useful in detecting and mapping the presence or absence of particular DNA sequence within chromosomes
FISH
Number of kb used in FISH
200-400
Applied to provide specific localization of genes on chromosomes
FISH
FISH is also used for the rapid diagnosis of ___ and ___ which is acquired using specific probes
trisomies
microdeletions
FISH is ___ (more/less) cost effective than PCR
more
FISH has ___ (short/long) turn around time
short
The basic requirement for FISH is for the DNA to be ___/___/___
undenatured
preserved
intact
The target DNA is also called as the ___
template
To separate DNA strands and allow probe access to target DNA
Denature
Binding the probe to target DNA
Hybridize
Specimens used for metaphase cell FISH
Blood
Bone Marrow
Skin Fibroblast
Chorionic villi
Amniocytes
Tumors
Specimens used for interphase FISH
Direct preparation
Uncultured cells from blood, bone marrow, cytospins
Smears made from blood, buccal cells, bone marrow
Specimens used for interphase FISH
Indirect preparation (Paraffin Embedded Tissue Sections)
Tumors
Products of conceptions
FFPE means ___
Formalin fixed paraffin embedded tissue
Metaphase/Interphase FISH:
Gold standard and routinely done
Metaphase
Metaphase/Interphase FISH:
Done on cultured cells
Metaphase
Metaphase/Interphase FISH:
Allows direct visualization of chromosomes and exact position of signals
Metaphase
Metaphase/Interphase FISH:
Useful in the detection of structural changes in the genokme
Metaphase
Metaphase/Interphase FISH:
More rigorous procedure
Metaphase
Metaphase/Interphase FISH:
Used for copy number changes
Metaphase
Metaphase/Interphase FISH:
Can be modified for de novo detection
Metaphase
Metaphase/Interphase FISH:
May also be done on uncultured specimens
Interphase
Metaphase/Interphase FISH:
Advantageous in the rapid screening of many nuclei for prenatal diagnosis and newborn studies
Interphase
Metaphase/Interphase FISH:
Also beneficial in the study of samples with a low mitotic index such as most solid tumors
Interphase
Metaphase/Interphase FISH:
Major disadvantage is the inability to detect unknown structural chromosomal changes
Interphase
Metaphase/Interphase FISH:
Same day turn around time
Interphase
Metaphase/Interphase FISH:
Translocation can be detected
Interphase
Metaphase/Interphase FISH:
Used for screening
Interphase
Sample for interphase fish:
For ploidy analysis during prenatal studies
Amniocytes
Sample for interphase fish:
For ploidy analysis in newborns
Peripheral blood smears
Sample for interphase fish:
Translocation or copy number analysis in cancer studies
Bone marrow aspirate smear or direct harvest
Complementary sequences of target nucleic acids tagged or labeled with fluorophores
FISH probes
FISH probes can be (3):
DNA
RNA
Nucleic acid analogs
FISH probes size ranges from __ to __ base pairs
20-1000
Direct/Indirect labeling:
Fluorophores are directly attached to the probe
Direct
Direct/Indirect labeling:
Less sensitive
Direct