Abstract
The structural organization of a family of repeated DNA sequences in the chicken genome has been determined by hybridization of a cloned repeated DNA sequence to Southern blots of total DNA. The length of the cloned DNA fragment is 3600 nucleotide pairs. This fragment consists principally, if not entirely, of a single repeated DNA sequence occurring only once within the cloned fragment. In the chicken genome, the family of repeated DNA sequences homologous to the cloned sequence has a limited number of alternative forms. Some of the restriction fragments of total DNA to which the cloned sequence hybridizes correspond to those expected from the location of restriction endonuclease cleavage sites within the cloned sequence. There are also a limited number of other genomic restriction fragments, each present in multiple copies, to which the cloned sequence hybridizes but which do not relate in any obvious way to the length of the cloned sequence. These various restriction fragments differ from one another in that they appear to be present in unequal amounts in total DNA, and many of them do not contain the entire cloned sequence. This study provides some new information about the structure of repeated DNA sequences in the chicken genome. The copies of a repeated DNA sequence may differ from one another both by minor variations in nucleotide sequence (divergence) and in more substantial ways as would be expected to arise from processes such as insertion, deletion, and translocation. In addition to this description of a single cloned repeated DNA sequence from the chicken genome, this paper reports the cloning of more than 100 different restriction fragments of chicken DNA, each of which contains one or more repeated DNA sequences.
Highlights
DNA sequences in the chicken genome has been deter- growth of knowledge about their structure and genomic ormined by hybridization of a cloned repeated DNA se- ganization [4, 14].Repeated sequenceswith a lower repetition quence to Southern blots of total DNA
The physical basis for this enrichment is not understood at present, but it has been observed by others that Eco RI fragments of total DNA containing another repeated sequence in the chickengenome, ribosomal DNA, bind to the RPC-5 matrix with a very high or a very low affinity [33]
In this paper,the isolation of 146different clones containing chicken repeated DNA sequences is reported. Since these clones were constructed by preselection of a fraction of Eco RI fragments of total DNA that has a low affinity for the RPC-5 chromatographymatrix, there may have been an initial selection for a particular subset of chicken repeated DNA before cloning
Summary
Sincethe discovery of repeatedsequences in DNA (l), isolated from the pooled blood of many individuals (Gallus gallus, considerable information hasbeen obtained about their struc- White Leghorn variety) by a procedure describedpreviously[21]. Ligation of Eco RI Restriction Fragments of Chicken DNA with of culture was divided among eight 40-ml gradients. Supplements and grown overnight a t 37°C ina separate well of a Hybridization-DNA fragments were transferred from agarose microtiter tray. These cultures were replica-plated to the surface of gels to nitrocellulose filters by the method of Southern [30]. Presence of chicken DNA sequencesby a modification of the standard The radioactiveDNAprobe was mixed withheterologouscarrier colony filter hybridization procedure [27] as described in detail in the DNA and RNA to obtain afinal concentration of carriers in the miniprint supplement.'.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
