Negative stain
(Redirected from
Negative staining
)In
positive staining
, in which the actual specimen is stained.
Bright field microscopy
For bright-field microscopy, negative staining is typically performed using a black ink fluid such as nigrosin and India ink. The specimen, such as a wet bacterial culture spread on a glass slide, is mixed with the negative stain and allowed to dry. When viewed with the microscope the bacterial cells, and perhaps their spores, appear light against the dark surrounding background. An alternative method has been developed using an ordinary waterproof marking pen to deliver the negative stain.[1]
Transmission electron microscopy
In the case of
flagella, biological membrane structures and proteins or protein aggregates, which all have a low electron-scattering power. Some stains, such as osmium tetroxide and osmium ferricyanide, are very chemically active. As strong oxidants, they cross-link lipids mainly by reacting with unsaturated carbon-carbon bonds, and thereby both fix biological membranes in place in tissue samples and simultaneously stain them.[3][4]
The choice of negative stain in
electron microscopy
can be very important. An early study of plant viruses using negatively stained leaf dips from a diseased plant showed only spherical viruses with one stain and only rod-shaped viruses with another. The verified conclusion was that this plant suffered from a mixed infection by two separate viruses.
Negative staining at both light microscope and electron microscope level should never be performed with infectious organisms unless stringent safety precautions are followed. Negative staining is usually a very mild preparation method and thus does not reduce the possibility of operator infection.
Other applications
hexagonal H-II cylinders(H) lipid
phases by negative staining.Negative staining transmission electron microscopy has also been successfully employed for study and identification of aqueous lipid aggregates like
hexagonal HII cylindrical (H) phases (see figure).[5]
References
- PMID 1714705.
- ISBN 0-470-84479-5.
- ISBN 978-0-7637-0192-5.
- ISBN 0-521-63287-0.
- S2CID 39712301.
External links
- "Negative staining for dummies". Retrieved 2009-06-06.
- "Negative staining". Archived from the original on 2012-12-25. Retrieved 2009-06-06.