Phenotypic features and functions known to depend on the presence of the Y chromosome or the H-Y antigen are discussed in relation to structural anomalies of the Y chromosome and other abnormalities of sexual and somatic development.

A synopsis of the human Y chromosome.

In a progeny of a selfed individual of the dark red-flowered cultivar ‘Roter Vogel’ some white-flowered plants appeared as the result of a mutation of the genetic factor Anl involved in anthocyanin synthesis. The white flowers of these plants had red spots owing to back-mutations in the dermal cells of the young corolla.

Regulation of gene action in Petunia hybrida: Unstable alleles of a gene for flower colour.

The first known example of a human female with more than one euchromatic X chromosome in somatic cells is presented, viz. a child with 2 normal X chromosomes and the long arm of a third X translocated onto one of the No. 22 chromosomes. In cultured lymphocytes there occurred, in addition to the ordinary Lyon pattern of X chromosome inactivation, 2 other patterns in which (1) 2 normal X chromosomes, and (2) one X and the t(X;22) were euchromatic. As the inactivation within the translocation chromosome did not spread onto chromosome 22, the clinical symptoms of the child had to be attributed to the excess of active X material, not to monosomy 22.



Contrary to this, absence of heterochromaty of the Y chromosome does not influence the phenotype, as shown by the case of mixed gonadal dysgenesis with non-fluorescing Y presented. Possible reasons for this difference include: (1) The differences between facultative X and constitutive Y heterochromatin; (2) Different cytologic criteria for heterochromatin may not mean the same kind of inactivity; (3) Differences in phenotypic expression may be due to different chromosomal behaviour among tissues; (4) Late replication and decondensation may not equate genetic inactivity in terms of transcriptional inactivity.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1601-5223.1977.tb01213.x

Clinical and cytological aspects of sex chromosome activity

We describe here a novel approach to the dissection of chromatin structure by extracting DNA fragments from digested nuclei irreversibly immobilized (via proteins) on Celite columns. Three successive gradients (NaCl, LiCl-urea, temperature) are used to release three families of DNA fragments: namely, the 'DNA adherence' classes DNA-0, DNA-I and DNA-II, respectively. This 'protein image' DNA chromatography separates DNA fragments in accordance with the tightness of their bonds with proteins in situ. There are at least two DNA-skeleton attachment sites differing from each other by their resistance to the dissociating agents used as well as their susceptibility to DNAase I and S1 nuclease treatments, DNA cross-linking and single-stranded breaks. Several lines of evidence show a specific, topological rather than chemical, DNA-protein linkage at the tight attachment site. A hierarchy of chromatin loops demarcated by these attachment sites was determined. The technique described is generally applicable and can be used both to probe DNA-protein interactions and to map specific DNA sequences within the chromatin domain.

Differential dissociation of chromatin digests: a novel approach revealing a hierarchy of DNA-protein interactions within chromatin domains

Isolation and cell-free translation of a human immunoglobulin light chain messenger RNA

MOUSE immunoglobulin (Ig) mRNAs have been the subject of intensive study. Purification of Ig light chain mRNAs from myeloma or plasmacytoma cells has been monitored by translation in vitro, and studies have been directed towards sequence determination and gene titration Moreover, partial purification of Ig heavy chain mRNA has also been achieved1–5. No comparable work on the Ig mRNA of any other species has yet been published. We report here the preparation, fractionation and translation in vitro of mRNA from cells of a cloned normal human B lymphocytic cell line. RPMI 1788 (ref. 6). grown in tissue culture. Human Ig μ chains were identified in the translation product by specific immunoprecipitation and electrophoretic mobility in sodium dodecyl sulphate (SDS)-urea polyacrylamide gels.

Carol K. Klukas

Papers

Translation of human immunoglobulin heavy chain mRNA in vitro.

Non-histone proteins

Non-histone proteins and transcription

Regulating gene expression in differentiation