The location of (6,7-3H) oestradiol-17-beta in mouse vagina

The retention of [6,7-3H]oestradiol-17β in fractions of the mouse vagina has been studied after direct application of 50 pg. of this oestrogen. Tritium was present in both epithelial and stromal cells. Most of the tritium was associated with the nuclear fraction from the epithelium. The nuclear binding was acid labile and only 30% of the nuclear tritium was extracted with 2 m-NaCl. The results obtained by sonic disruption of the nuclei were compatible with the view that the [6,7-3H]oestradiol-17β was associated with chromatin.

No evidence was obtained for the presence of a cytoplasmic oestradiol-binding component in the epithelium.

An attempt to isolate an oestradiol receptor from nuclei by adsorption on oestradiol-17-beta

The binding of nuclear proteins from dimethylbenzanthracene (DMBA)-induced rat mammary tumours and other natural and synthetic proteins to columns of oestradiol-17β (oestradiol) has been studied. A wide range of proteins, but not DNA, bind to oestradiol under these conditions and this binding is disrupted by acid. Both histone and acidic nuclear protein fractions bind to oestradiol and the bound fraction had, in both cases, the ability to bind [6,7-3H]oestradiol. Acrylamide gel electrophoresis showed that more than one protein from both the acidic and basic nuclear protein fractions was bound to the oestradiol. More poly-l-glutamic acid and poly-l-glycine was bound to the oestradiol than poly-l-lysine. Oestradiol columns bound more protein from both the histone and acidic protein fraction than did columns of oestrone. Oestradiol bound more acidic protein than testosterone or progesterone but this difference was not evident with the histone fraction.

Equilibrium dialysis experiments showed that the ability of a protein to bind to oestradiol was not related to its association constant with [6,7-3H] oestradiol.

The acidic nuclear proteins had a higher association constant than the histone fraction.

These results are discussed in relation to the purification of oestradiol receptors and to the binding of [6,7-3H]oestradiol in vivo.

The association of [6,7-3H]oestradiol with a nuclear protein

The binding of [6,7-3H]oestradiol to nuclei from rat dimethylbenzanthracene-induced (DMBA) mammary tumour, uterine epithelium, anterior pituitary and kidney has been studied. Digestion of nuclei labelled in vivo with [6,7-3H]oestradiol, with RNase, DNase and trypsin indicated that only the last enzyme released tritium from the nucleus, indicating that the receptor is a protein. The optimal concentration of sodium chloride for extracting the oestradiol-receptor complex from tumour nuclei was 1-molar. This concentration was required even after enzymic removal of most of the DNA and RNA. Sodium deoxycholate also extracted oestradiol from nuclei but at the same time dissociated the oestradiol-receptor complex. An attempt was made to fractionate the oestradiol-receptor complex on Sephadex and Biogel columns.

The intranuclear localization of [6,7-3H]-oestradiol-17-beta in dimethylbenzanthracene-induced rat mammary adenocarcinoma and other tissues

The intranuclear localization of [6,7-3H]oestradiol-17β (oestradiol) has been studied in nuclei from dimethylbenzanthracene (DMBA)-induced rat mammary adenocarcinoma, anterior pituitary, uterine epithelium and kidney. The evidence suggests that, with the possible exception of uterine epithelium, most of the oestrogen is associated with an acid-labile nonhistone component of the chromatin. No evidence has been found to suggest that oestradiol is associated with any particular type of chromatin. These results are compatible with the view that oestradiol affects cellular function in some tissues by altering the priming ability of the chromatin DNA.

The localization of [6,7-3H]oestradiol-17-beta in rat uterus

The uptake of [6,7-3H]oestradiol-17β (oestradiol) by the rat uterus in vivo has been studied. By pressing uteri between two glass plates much, but not all, of the epithelium is removed with minimal effect on the underlying stroma and myometrium. This procedure removes 11 % of the DNA, 10·6 % of the radioactivity and about 3 % of the wet weight of the intact uterus, indicating that, as judged from the DNA content, there is no accumulation of [6,7-3H]oestradiol in the epithelium relative to the rest of the uterus. In the epithelium, the major portion of the [6,7-3H]oestradiol was in the soluble fraction although a considerable amount of the radioactivity was associated with the nuclei. Similar results were obtained with nuclei isolated by differential or gradient centrifugation. It has been shown that an interchange of [6,7-3H]oestradiol can occur between the nucleus and cytoplasm and that, under the experimental conditions used, the equilibrium favours the cytoplasm.

Some of the [6,7-3H]oestradiol in the soluble fraction from uterine epithelium was associated with a component of high molecular weight that may be a protein.

The metabolism of steroids by tissue from normal and neoplastic rat breast

The metabolism of oestrone, dehydroepiandrosterone (DHA) and testosterone by normal mammary gland tissue from pregnant rats and by dimethylbenzanthracene (DMBA)-induced mammary tumours has been investigated.

Oestradiol was the only compound regularly formed from oestrone. DHA was mainly converted to androst-5-ene-3β,17β-diol (Δ5-androstenediol), but another compound with the characteristics of an hydroxylated derivative of DHA was also formed. These tissues also had Δ4-5α-hydrogenase, 3-oxosteroid reductase and 17β-hydroxysteroid oxidoreductase activities when testosterone was used as substrate. Hormone-dependent and -independent tumours had higher enzyme activities towards oestrone and testosterone than had normal mammary tissue from pregnant rats. This difference cannot be accounted for solely by the difference in the cellularity of these tissues. The production of oestradiol by the hormone-dependent tumours was related to the growth rate of the tumour. No similar relationship was found for the metabolism of testosterone. Evidence is presented that hormone-independent tumours might be able to metabolize more oestrone than dependent tumours of similar growth rates.

The Opsonic Action of Serum

It has been shown by Gordon, Whitehead and Wormall (1) that ammonia-treated serum, in which the complement is entirely inactivated through destruction of the fourth component, is nevertheless still able to opsonise staphylococci. This fact indicates that the whole complement system is not necessary for opsonic action, a view supported by further data described by Gordon, Whitehead and Wormall (2), Gordon (3) and Gordon and Thompson (4).

Recently Maltaner (5) has shown that a suspension of leucocytes, either unheated, or heated at 55°C. for ½ hour, can supply fourth component to ammonia-treated serum, and that in this respect the heated suspension is actually more active than the unheated. The suspension of leucocytes acts in conjunction with the ammonia-treated serum in the same way as heated normal serum has been shown to do.