Genie and Non-genic Parts of the Chromosome 55 



This may mean that actually DNA could be used from nucleus to 

 nucleus. It is difficult to reconcile such facts with the genie nature of 

 DNA as well as the genie nature of bacterial transformations. We 

 shall return to this problem repeatedly. (See the previous discussion 

 on bacterial transduction via phage, which is on a similar level.) 



Another group of relevant facts relates to the basic proteins in 

 the chromosome. A distinction has been made between structural 

 proteins which keep the chromosome together and are not easily dis- 

 solved, and the simpler protamines which can be removed without 

 changing the chromosomal structure (Mirsky). These proteins are 

 not found in constant quantity from cell to cell. It is maintained that 

 sperm heads, consisting of closely packed chromosomes, are formed 

 mostly of DNA, with only a small portion of protamine added, which 

 would seem to favor DNA as genie material. But in all these deliber- 

 ations it should be kept in mind that we are not dealing with the 

 original substances in situ, which might be very different from the 

 extracts in vitro; and, further, that the quantity of protein needed is 

 probably below that accessible analytically. However, work in these 

 fields progresses so fast that it is unwise to draw more than pre- 

 liminary conclusions. 



A last group of facts favoring DNA as the genie material comes 

 from virus studies. Some viruses consist mainly or totally of nucleic 

 acids, even crystallizable, without losing their infective power. A 

 more special fact is that when a particle of the bacteriophage T2 

 attaches itself to a bacterium, most of the DNA of the phage enters 

 the cell, and most of the sulfur-containing protein remains outside 

 (Hershey, 1953; Hershey and Chase, 1951). It is, however, not 

 known whether sulfur-free protein enters the cell and whether this is 

 incorporated in the phage progeny, and further whether the DNA ( or 

 its constituents ) is directly or indirectly taken into the phage progeny. 

 Thus the authors conclude that a separation of the phage into genetic 

 and non-genetic parts is possible, but they are not willing to say which 

 is the genetic part. We have mentioned that another powerful argu- 

 ment against the genie nature of DNA is to be derived from polytenic 

 chromosomes which multiply their DNA immensely while assuming 

 extreme non-genic functions. The discussion of this will be taken up in 

 a later chapter, where the facts will be interpreted as excluding the 

 genie nature of DNA. 



