See Also: Androgen-insensitivity(health)
Androgen insensitivity syndrome, complete(health)
Complete androgen insensitivity syndrome(health)
Herbal medicine (botanical medicine, herbology, phytomedicine)(health)
pain insensitivity, congenital(medicine)
Congenital insensitivity to pain(medicine)
androgen(encyclopedia)
androgen(dictionary)
Androgen(medicine)
Androgen(health)

restriction nuclease (medicine) and Androgen-insensitivity (health)


restriction nuclease (medicine)


restriction nuclease -->
restriction endonuclease
<enzyme, molecular biology> Class of bacterial enzymes that cut DNA at specific sites. In bacteria their function is to destroy foreign DNA, such as that of bacteriophages (host DNA is specifically modified at these sites).

Type I restriction endonucleases occur as a complex with the methylase and a polypeptide that binds to the recognition site on DNA. They are often not very specific and cut at a remote site.

Type II restriction endonucleases are the classic experimental tools. They have very specific recognition and cutting sites. The recognition sites are short, 4-8 nucleotides and are usually palindromic sequences. Because both strands have the same sequence running in opposite directions the enzymes make double stranded breaks, which, if the site of cleavage is off centre, generates fragments with short single stranded tails, these can hybridise to the tails of Other fragments and are called sticky ends.

They are generally named according to the bacterium from which they were isolated (first letter of genus name and the first two letters of the specific name). The bacterial strain is identified next and multiple enzymes are given Roman numerals. For example the two enzymes isolated from the R strain of E. Coli are designated Eco RI and Eco RII.


Androgen-insensitivity (health)


The androgen-insensitivity syndrome is a congenital condition identified by a 46, XY sex chromosomal karyotype in girls or women who appear externally to be not sexually different from normal females, except in some cases for a swelling or lump in each groin, or for the absence or sparseness of pubic and axillary hair after puberty. The cells of the body are unable to respond to the male sex hormone, which is made in the testes in normal amounts for a male. They respond instead to the small amount of female sex hormone, estrogen, which is normally made in the testes. The effect before birth is that masculine internal development commences but is not completed. It goes far enough, however, to prevent internal female development. Externally, the genitalia differentiate as female, except for a blind vagina, which is usually not deep enough for satisfactory intercourse and needs either dilation or surgical lengthening in or after middle teenage. There is no menstruation and no fertility. Breasts develop normally. Incidence of occurrence is approximately one in 500 births.