Decrease of estrogen receptors induced by 17 beta-estradiol and progesterone in cultured rabbit endometrial cells

A whole cell technique to measure estradiol receptors in cultured rabbit endometrial cells is described. The estradiol receptors measured appear to be composed of at least two components: one component has high affinity but low capacity, while the other component has low affinity but high capacity. Using the assay, the effects of estradiol and progesterone pretreatment were examined on the estradiol receptor levels. It was found that both of the hormones decreased the number of estrogen receptors in the cultured cells. The finding that estradiol decreased its own receptors was unexpected and its possible relevance is discussed.     

A spectrofluorimetric investigation of calf thymus DNA modified by BP diolepoxide and 1-pyrenyloxirane

7β,8α-Dihydroxy-9α,10α-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BP diolepoxide, $\text{1}$) and 1-pyrenyloxirane ($\text{2}$) bind chemically to calf thymus DNA. The fluorescence efficiency of pyrenyl groups in mutagen modified DNA varies appreciably with its conformation and decreases in the order: pyrenees, modified denatured DNA and modified native DNA. A particularly interesting observation is that the fluorescence efficiency of mutagen modified DNA intensifies substantially upon denaturation. Our results suggest that the pyrenyl groups in mutagen modified DNA are intercalated between the base pairs of DNA. Since both $\text{1}$ and $\text{2}$ are powerful frame-shifting mutagens for S. typhimurium TA-98, the intercalative covalent binding of these compounds to DNA may provide a molecular basis for their mutagenic activity.     

Generation of ATP by chloroplasts through solvent perturbation.

A two-stage method was discovered for generating ATP by chloroplasts in the dark at constant pH through solvent perturbation. With cold acetone as the perturbing solvent, the yield of ATP was found to increase with the volume percent of acetone in the first stage medium. The results are difficult to explain in term of the proton gradient model, but is consistent with the conventional model of prior water formation and subsequent ATP generation.     

Purification of bull sperm hyaluronidase by concanavalin-A affinity chromatography.

A new method for obtaining highly purified hyaluronidase (hyaluronate glycanohydrolase EC 3.2.1.25) in high yield is described. Bull seminal plasma was fractionated with (NH4)2 SO4 and the 30 to 65% saturation fractions were applied to a DEAE-cellulose column. The first protein peak contained hyaluronidase, beta-N-acetylglucosaminidase and beta-glucuronidase. The latter two enzymes were separated by gel filtration on Sephadex G-200. The hyaluronidase was further purified by a Concanavalin-A Sepharose 4B affinity column. By gradient elution with alpha-methyl-D-glucoside a fraction which had a specific activity of 1998 units/mg protein (57 942 National Formulary Standard units/mg protein) was obtained. The highly purified enzyme showed one major protein band on acrylamide gel electrophoresis at pH 4.3. The purified hyaluronidase did not show any beta-glucuronidase or beta-N-acetylglucosaminidase activities. The percent yield of purified hyaluronidase calculated on the basis of total activity was ten times higher than by any pervious method [Yang, C.H. and Srivastava, P.N. (1975) J. Biol. Chem. 250, 79-83].     

Interactions of alpha- and beta-N-acetyl-D-glucosamines with hen and turkey lysozymes.

The binding constants of alpha- and beta-GlcNAc to hen and turkey lysozymes [EC 3.2.1.17] were determined at various pH's using the method proposed by Ikeda and Hamaguchi (1975) J. Biochem. 77, 1-16). The pH dependence of the binding of beta-GlcNAc to hen lysozyme was essentially the same as that for turkey lysozyme. The pH dependence curves of the binding constants of beta-GlcNAc to hen and turkey lysozymes were interpreted in terms of the participation of Glu 35 (pK 6.0), Asp 52 (pK 3.5), Asp 48 (pK 4.5), and Asp 66 (pK 1.5). The binding constants of alpha-GlcNAc to hen and turkey lysozymes were the same below pH 3.5 but were different above this pH. The main participant residues in the binding of alpha-GlcNAc were Glu 35, Asp 48, and Asp 66 for hen lysozyme and Glu 35 and Asp 66 for turkey lysozyme. The results obtained here were well explained by the following assumptions: (1) above about pH 4, alpha-GlcNAc binds to hen lysozyme in both alpha- and beta-modes, which correspond to the binding orientation of alpha-GlcNAc and that of beta-GlcNAc, respectively, as determined by X-ray crystallographic studies, but it binds predominantly in the beta-mode below about pH 4, (2) beta-GlcNAc binds to hen and turkey lysozymes predominantly in the beta-mode above about pH 4 and in both alpha- and beta-modes below pH 4, and (3) alpha-GlcNAc binds to turkey lysozyme predominantly in the beta-mode over the whole pH range studied.     

Inhibition of bull and rabbit sperm enzymes by alpha-chlorohydrin.

High concentrations of alpha-chlorohydrin were found to inhibit hyaluronidase, beta-glucuronidase, and aryl sulphatases in bull and rabbit spermatozoa, but not acrosin and neuraminidase. Preincubation of the enzyme and alpha-chlorohydrin was essential to achieve the maximum inhibition which was irreversible.     

Single-cell transcriptomic atlas of primate cardiopulmonary aging

Aging is a major risk factor for many diseases,especially in highly prevalent cardiopulmonary comorbidities and infectious diseases including Coronavirus Diseas...     

SARS-CoV-2 envelope protein causes acute respiratory distress syndrome (ARDS)-like pathological damages and constitutes an antiviral target

Cytokine storm and multi-organ failure are the main causes of SARS-CoV-2-related death. However, the origin of excessive damages caused by SARS-CoV-2 remains largely unknown. Here we show that the SARS-CoV-2 envelope (2-E) protein alone is able to cause acute respiratory distress syndrome (ARDS)-like damages in vitro and in vivo. 2-E proteins were found to form a type of pH-sensitive cation channels in bilayer lipid membranes. As observed in SARS-CoV-2-infected cells, heterologous expression of 2-E channels induced rapid cell death in various susceptible cell types and robust secretion of cytokines and chemokines in macrophages. Intravenous administration of purified 2-E protein into mice caused ARDS-like pathological damages in lung and spleen. A dominant negative mutation lowering 2-E channel activity attenuated cell death and SARS-CoV-2 production. Newly identified channel inhibitors exhibited potent anti-SARS-CoV-2 activity and excellent cell protective activity in vitro and these activities were positively correlated with inhibition of 2-E channel. Importantly, prophylactic and therapeutic administration of the channel inhibitor effectively reduced both the viral load and secretion of inflammation cytokines in lungs of SARS-CoV-2-infected transgenic mice expressing human angiotensin-converting enzyme 2 (hACE-2). Our study supports that 2-E is a promising drug target against SARS-CoV-2.Subject terms: Cell death, Molecular biology