Variation in regulation of steroid sulphatase locus in mammals

Inactivation (lyonization) of one of the two copies of X-linked genes occurs in female mammals, thereby reducing the number of active copies to that of the male. It has been suggested that genes subject to lyonization would be expected to be preserved as a linkage group during mammalian evolution. A short region of the human X chromosome containing several genes, including that necessary for the expression of steroid sulphatase (STS), is exceptional in that it apparently escapes X-inactivation. As it is not apparent why the linkage of genes not subject to X-inactivation should be conserved, we have examined the expression of the STS gene in mice (it has been shown recently that this gene is X-linked). Enzyme levels were determined in normal males and females and in the progeny of crosses in which the sex reversing factor, Sxr, was segregating to produce XX males. We report here that in contrast to the situation in humans, the STS gene in mice is subject to the normal pattern of X-inactivation.     

Determination of bacteriophage lambda tail length by a protein ruler

How the size and shape of living structures are determined by genetic information is one of the fundamental problems in biology. Here I describe a study in which the size of a biological supramolecular structure was changed in a predictable way by in vitro genetics, with the size both before and after manipulation being exactly determined. I have studied the tail of bacteriophage lambda, whose length is determined by the length of the 'ruler protein', the product of gene H. The length of the tail can be decreased or increased by deleting the middle part of gene H or by forming a small duplication there, and the length of the tail is proportional to the size of the protein. These results can be regarded as a special case of protein engineering, namely supramolecular protein engineering.