fluorescent in situ hybridizationmedicine

Newer techniques such as fluorescent in situ hybridization (FISH) have much higher rates of sensitivity and specificity. FISH also provides results more quickly because no cell culture is required. This technique can detect smaller genetic deletions involving one to five genes. It is also useful in detecting moderate-sized deletions such as those causing Prader-Willi syndrome, which is...

...them in the laboratory, and allowing the resultant embryos to grow until they reach the early blastocyst stage of development, at which point a single cell is removed from the rest and harvested for fluorescent in situ hybridization (FISH) or molecular analysis. The problem with this procedure is that one cell is scant material for diagnosis, so that a large array of tests cannot be performed....

As briefly mentioned above, hybridization is another mechanism by which introduced species can cause extinction. In general, species are considered to be genetically isolated from one another—they cannot interbreed to produce fertile young. In practice, however, the introduction of a species into an area outside its range sometimes leads to interbreeding of species that would not normally...

...areas of Africa and South America. Its nutritive value is limited by its low lysine content. Much recent research has involved development of a corn with higher lysine content. Mutants have been produced containing much less zein but possessing protein with higher than normal lysine and tryptophan contents, sometimes increased as high as 50 percent. These corns, called Opaque-2 and Floury-2,...

In certain temperate fern genera, such as spleenworts (Asplenium), wood ferns (Dryopteris), and holly ferns (Polystichum), hybridization between species (interspecific crossing) may be so frequent as to cause serious taxonomic problems. Hybridization between genera is rare but has been reported between closely related groups. Fern hybrids are conspicuously intermediate in...

The processes of hybridization and polyploidization have produced many valuable crops. Normally during sexual reproduction, two haploid gametes (n) fuse to form a diploid zygote (2n). In polyploidy, one or both gametes remain diploid because the chromosomes fail to separate during an early stage of meiosis. Consequently, fusion of three or more complete sets of chromosomes produce...

During the 20th century planned hybridization between carefully selected parents has become dominant in the...

...Much less energy is required to promote electrons from 2s orbitals into 2p orbitals in boron atoms with the result that boron compounds are always covalent. The boron orbitals are hybridized to either the sp² (when boron forms bonds with three other atoms) or the sp³ (when boron forms bonds with four atoms) configuration (see chemical...

...ions have come to be recognized. The first are the “classical” carbonium ions, which contain a trivalent carbon atom centre. The carbon atom is in an sp² state of hybridization—that is, three electrons of the carbon atom occupy orbitals formed by the combination (hybridization) of three ordinary orbitals, one denoted s and two, p. All three...

The discussion is not yet complete, however. If this description of carbon were taken at face value, it would appear that, whereas three of the CH bonds in methane are formed from carbon 2p orbitals, one is formed from a carbon 2s orbital. It is well established experimentally, however, that all four bonds in methane are...

...electricity well at room temperatures. Their ability to conduct electricity is caused by impurities. Such impurities are deliberately added to silicon in the manufacture of integrated circuits. In fluorescent lamps the visible light is emitted by impurities in the phosphors (luminescent materials).

...the inert gases, Claude found that passing electrical current through them produced light, and in 1910 he developed the neon lamp for use in lighting and signs. With the introduction of inner fluorescent coatings, the fluorescent light was developed and began to replace the incandescent lamp in industrial and certain home-lighting uses.

Despite these inventions, electric discharge lamps were little used in interior lighting until the development in the 1930s of the fluorescent tube. This is a long tube with a mercury-vapour filling, and inner walls coated with a material which fluoresces white or near...

New analytic methods in molecular biology have made genetic studies for the characterization and identification of bacteria more practical. The DNA hybridization technique is an example. A strand of DNA from a known species (the probe) is radioactively labeled and “mixed” with DNA from an unidentified species. If the probe and the unknown DNA are from identical species, they will...