Minisatellite DNA

A form of epilepsy (Table 27-4) appears to be a result of repeats of a (G + C)-rich sequence that may be a dodecamer.405 Dinucleotide repeats and other "minisatellite" DNA sequences are also associated with instability of DNA and may undergo expansion.419 21 A pentanucleotide repeat (CCTTT) is associated with increased expression of the nitric oxide synthase gene NOS2A. Persons with n = 14 were found to have enhanced resistance to development of diabetic retinopathy. This seems to be a case of a beneficial "gain of function" mutation.422... 

A delineated class of DNA, minisatellite DNA, has been found to be moderately to extremely variable in certain eukaryote genomes.1-3 Minisatellite DNA is composed of tandem repeats of a core or consensus sequence reiterated a low to moderate number of times (relative to satellite DNA, where consensus motifs, or variants thereon, may be repeated tens of thousands of times). For convenience, minisatellite DNA as defined here includes simple sequence4 and microsatellite5 DNA. Thus, minisatellite consensus sequences range from 2 to approximately 70 base pairs (bp). Several different minisatellite families (members of a family have consensus sequence similarities) have been described.6... 

Much of the human genome consists of repetitive DNA. Describe the difference between microsatellite and minisatellite DNA. How is this repetitive DNA useful for identifying individuals by the technique of DNA fingerprinting ... 

Hanotte, O., Burke, T., Armour, J.A.L. Jeffreys, A.J. (1991). Hypervariable minisatellite DNA sequences in the Indian Peafowl Pavo cristatus. Genomics, 9, 587-97. 

Fig 1 A generalised representation of the structure of hypervariable minisatellite DNA. See text for details. 

A probe capable of recognizing and binding to minisatellite DNA is prepared and is used to wash the filter, in order that it may bind to homologous sequences immobilized on the membrane surface. The required match between a probe and target can be regulated by controlling temperature and/or the ionic strength... 

The way in which individuals differ at hypervariable loci is elucidated by restriction analysis of chromosomal DNA. This is made possible by the fact that restriction sites for many restriction endonucleases (see) do not occur in minisatellite DNA. This means that when the chromosomal DNA is digested with such an endonuclease all the species of minisatellite DNA remain intact, cleavages having occurred on either side of them. Thus individuals with different numbers of tandemly repeated monomers at specific hypervariable loci will produce restriction fi-a ents of different length from those loci these can be separated by gel electrophoresis and detected with an appropriate probe after Southern blotting (see). 

Pena, H.B., de Souza, C.P., Simpson, A.J. and Pena, S.D. (1995) Intracellular promiscuity in Schistosoma mansoni nuclear transcribed DNA sequences are part of a mitochondrial minisatellite region. Proceedings of the National Academy of Sciences USA 92, 915-919. 

Previously described methods for plant DNA extraction (e.g., see Hillis et al.16 and references therein) have usually either required CsCl purification or resulted in a final DNA product that often contained other contaminating substances. For restriction site analysis of chloroplast or mitochondrial genomes, where usually less than 0.5 fig of DNA per individual is required, any procedure was appropriate and practical. However, for minisatellite restriction enzyme analyses, typically 5-10 jtg of DNA is required per individual per trial. For such analyses, obtaining enough DNA from an individual for several trials using CsCl is costly and time-consuming ... 

Obtain DNA from any strain of the M13 bacteriophage (commercially available) that has the minisatellite sequence indicated by Vassart et al ... 

In the mid-1980s, these techniques were replaced by direct analysis of the DNA polymorphisms. The first of such techniques, developed by Alec Jeffries utilized multilocus DNA probes. This technique is known as the restriction fragment length polymorphism (RFLP) testing. RFLP techniques are based on variable number of tandem repeats (VNTR), which are sequences of 10 to 60 bp (base pairs) of length, that lie adjacent to each other in the same chromosomal orientation (minisatellites). 

The next major change in the analysis of the DNA for paternity (and forensic) analysis incorporated the PCR amplification of microsatellites instead of minisatellites. Microsatellites are also formed by tandem repeats but consist of two to five nucleotides per repeat units. This means that the amplification requires less DNA (less than 1 ng) and the quality of the material may be less than ideal. This capability permits the analysis of some degraded DNAs. The potential number of loci is very large and the process is rapid it may be completed in a day or two. This system also has the benefit of lending itself to multiplexing and automation. In addition, several kits are available, and for some multiplexes inexpensive silver stain materials may be employed without expensive equipment. 

Jeffreys AJ, McLeod A, Tamaki K, Neil DL Monckton DG (1991) Minisatellite repeat coding as a digital approach to DNA typing. Nature 354 204-210. 

Devor EJ, Ivanovich AK, Hickok JM Todd RD (1988) A rapid method of confirming cell line identity DNA fingerprinting and minisatellite probe from M13 bacteriophage. Biotechniques 6 200-202. 

Jeffreys AJ, Wilson V Thein SL (1985a) Hypervariable minisatellite regions in human DNA. Nature 314 67-73. 

Vassart G, Georges M, Monsieur R, Brocas H, Lecarre AS Christophe D (1987) A sequence in M13 phage detects hypervariable minisatellites in human and animal DNA. Science 235 683-684. 

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