Hyperacetylation of histone H4 in rat testis spermatids

Acetate was incorporated efficiently into rat testis histones after an intratesticular injection of [3H]acetate. The pattern of in vivo acetylation of the testis histones was quite similar to the pattern of in vitro acetylation seen in a previous study with histones H3 and H4 acetylated to the greatest extent [13]. Acetylation of one or more of the major testis H2A variants was confirmed by analysis of these histones on high resolution polyacrylamide gels (PAGE) containing Triton X-100. Of the four variants, H2A.1 appeared to be labeled to the greatest extent. When testis cells were separated into highly enriched populations of specific cell types by centrifugal elutriation after an intratesticular injection of labeled acetate, histone H4 from all fractions of cells was acetylated, but histone H4 from the fraction of cells most enriched in elongating spermatids was hyperacetylated. Thus, the in vivo hyperacetylation of histone H4 which occurs in elongating spermatids is a physiological event which occurs during the relatively short time period when the entire complement of histones is replaced by more basic, protamine-like proteins, and therefore must be one of the key steps in this dramatic protein transition.

Acetylation of rat testis histones H2B and TH2B

The in vivo acetylation of rat testis histones H3 and H4 has been demonstrated in previous studies. In this study, analysis of purified histone fractions revealed the in vivo acetylation of histone H2B, the testis histone variant designated TH2B, and two or more of the histone H2A variants. These findings are quite significant, because it is possible that all of the core histones are acetylated in elongating spermatids at the time of removal of the entire histone complement for replacement by basic spermatidal transition proteins (S.R. Grimes and N. Henderson, 1983, Arch. Biochem. Biophys. 221, 108-116).

Occurrence of minute ring-shaped nucleoprotein particles in culture media conditioned by mammalian cells

Conditioned media of 21 mammalian cell lines have been examined by electron microscopic and biochemical techniques for the presence of a minute ring-shaped nucleoprotein particle (RSP). Electron microscopy showed the presence of RSP in 20 of the 21 cell lines tested. Comparative analyses of sex cell cultures for radioactive RSP, following 3H-thymidine incorporation, suggested that quantitative differences exist in the amount of RSP detectable in conditioned media of normal and pathologic cells. The cell lines tested included cells of different morphologies, origin and function

The association between HL-A antigens ankylosing spondylitis and sacro-iliitis

The second series antigen W27 has been found to have an increased frequency in ankylosing spondylitis (82 per cent of 17 patients) and juvenile rheumatoid arthritis (Still's disease) (29 per cent of 24 patients). Three family studies are presented, including one in which the antigen W27 occurs both in the absence and the presence of ankylosing spondylitis. It is suggested that this family illustrates that the relationship between W27 and sacro-iliitis is affected by non-HL-A genes. The development of clinical disease depends upon the coincidence of several factors in one individual, some of which are genetically controlled by two or more loci which are not necessarily linked.