What is used as a counterstain during Gram staining?
In Gram staining, crystal violet stains only Gram-positive bacteria, and safranin counterstain is applied which stains all cells, allowing the identification of Gram-negative bacteria as well
What is stained using the FISH technique?
Fluorescence in situ hybridization (FISH) is a laboratory technique for detecting and locating a specific DNA sequence on a chromosome The technique relies on exposing chromosomes to a small DNA sequence called a probe that has a fluorescent molecule attached to it
Is the counterstain used in the Gram stain a basic dye?
The counterstain used in the Gram stain is a basic dye In a completed Gram stain, gram-negative bacteria are colorless In a completed Gram stain, gram-positive bacteria are purple Cells viewed in darkfield microscopy appear similar to those stained with the negative stain
What counterstain is used?
The final step in gram staining is to use basic fuchsin stain to give decolorized gram-negative bacteria pink color for easier identification It is also known as counterstain Some laboratories use safranin as a counterstain; however, basic fuchsin stains gram-negative organisms more intensely than safranin
Which reagent is used as a counterstain?
The most common counterstain is safranin, which colors decolorized cells pink An alternate counterstain is basic fuchsin, which gives the decolorized cells more of a bright pink or fuchsia coloration
Is safranin a counterstain?
A counterstain, such as the weakly water soluble safranin, is added to the sample, staining it red Since the safranin is lighter than crystal violet, it does not disrupt the purple coloration in Gram positive cells
What is FISH and its use in karyotyping?
Fluorescence in situ hybridization (FISH) provides researchers with a way to visualize and map the genetic material in an individual’s cells, including specific genes or portions of genes This may be used for understanding a variety of chromosomal abnormalities and other genetic mutations
What is spectral karyotyping used for?
Spectral karyotype (SKY) is a karyotype in which the homologous pairs of chromosomes are manipulated in such a way that they have distinctive colors The SKY technique makes it easier for scientists to detect chromosomal abnormalities, as compared with a conventional karyotype
What is the difference between FISH technique and karyotyping?
Conventional karyotyping is limited to the detection of rearrangements involving more than 5 Mb of DNA The resolution of the FISH technique, using fluorescent probes, is about 100kb-1Mb in size It can turn almost any DNA into a probe 2
Why is decolorization the most important step in Gram staining?
The Gram stain is the most important staining procedure in microbiology This layer makes up 60-90% of the gram positive cell wall Decolorizing the cell causes this thick cell wall to dehydrate and shrink, which closes the pores in the cell wall and prevents the stain from exiting the cell
What is the purpose of a counterstain in the acid fast stain?
What is the function of the counterstain in the acid-fast staining procedure? The counterstain stains non-acid-fast bacteria blue if using Methylene Blue or green if using Brilliant Green
What is the best procedure for decolorization?
What is the best procedure for decolorization? Add decolorizing agent until run-off is clear This method allows the decolorizing agent to dissolve the outer membrane of Gram-negative cells and rinse out the crystal violet from the thin layers of peptidoglycan This causes the run-off to be purple
Which reagent is used as a counterstain quizlet?
The counterstain is Gram Safranin The decolorizer is Ethanol It is added to chemically change the shape of the dye molecule and trap it in the cell wall Iodine is used in the Gram stain
Could a counterstain other than safranin be used?
Why is it necessary? Could colors other than red be used? Safranin is used to stain the gram negative bacteria Yes, other colors can be used, such as methylene blue
Is methylene blue a counterstain?
This Methylene Blue is a light blue counterstain designed for counterstaining immunohistochemistry chromogens like DAB (GTX28196) It is an excellent counterstain for use with immunogold staining
Is Crystal Violet a counterstain?
For instance, in Gram staining, two dyes are used: the Crystal Violet and Safranin The Safranin is the counterstain used in this method
Why is safranin used as a counterstain in Endospore staining?
After the initial washing, a counter stain (safranin) is used The purpose of the counter stain is to stain the vegetative cells that lost the primary stain Therefore, endospores will appear green in color while the vegetative cells will pink/reddish in color under the microscope
What is a primary stain and a counterstain?
The primary stain (crystal violet) binds to peptidoglycan, coloring cells purple After the decolorizing step, a counterstain is applied (usually safranin, but sometimes fuchsine) to color the bacteria pink
What kind of probes can be used in FISH?
There are broadly three types of probe, each with a different range of applications: whole-chromosome painting probes; repetitive sequence probes and locus-specific probes Figure 4 Interphase FISH on a nucleus using an Exta-signal probe to detect the BCR/ABL translocation
What can FISH be used for?
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How are FISH probes made?
Probes are often derived from fragments of DNA that were isolated, purified, and amplified for use in the Human Genome Project The size of the human genome is so large, compared to the length that could be sequenced directly, that it was necessary to divide the genome into fragments
Can spectral karyotyping detect inversions?
Its strength lies in its ability to define translocations, marker chromosomes, and complex rearrangements, and to reveal cryptic change; it cannot, however, detect intrachromosomal rearrangements, such as duplications, very small deletions, or small paracentric inversions1
What is multiplex FISH?
Multiplex FISH (M-FISH) represents one of the most significant developments in molecular cytogenetics of the past decade In addition, the ability to accurately karyotype single metaphases without selection makes M-FISH the perfect tool in chromosome breakage studies and for characterizing clonal evolution of tumours
What is digital karyotyping?
Digital karyotyping uses short sequence tags derived from specific genomic loci to provide a quantitative and high-resolution view of copy number changes on a genome-wide scale Genomic tags are obtained using a combination of enzymatic digests and isolation of short DNA sequences