Equol: a contributor to enigmatic immunoassay measurements of estrogen

The efficacy of radioimmunoassay (RIA) for the measurement of estradiol-17 beta (E2) in murine plasma was investigated. When Sephadex LH-20 or celite column chromatography was used to separate E2 from estrone (E1) and other cross-reacting compounds, the results were erratic if small volumes of mouse plasma were resolved. Assay of a diethyl ether extract of plasma (500 microL) was the most practical method for estimating the concentration of estradiol-17 beta in mice. This method was used to determine the pattern of estrogen secretion during the estrous cycle, on the day of implantation and during pregnancy. No convincing change in estrogen secretion was observed in the diestrous/proestrous mouse. By comparison, estrogen levels were elevated during pregnancy. Taken together, these results implied that cross-reactive components in plasma masked low levels of endogenous estrogen. Further evaluation of mouse plasma and urine using a co-chromatography technique to examine estrogen elution from a reverse-phase HPLC system followed by GC/MS analysis indicated the presence of equol [7-hydroxy-3-(4-hydroxyphenyl)chroman], a phytoestrogen metabolite with a ring structure similar to estradiol-17 beta. Equol and possibly other cross-reactive components of plasma may account for the apparent lack of increased estrogen secretion during the mouse estrous cycle and on the day of implantation as determined by the radioimmunoassay of ether extracts of plasma.     

The amino acid sequence of equine milk lysozyme

The amino acid sequence of equine milk lysozyme has been elucidated. The study involves the determination of the sequence of the N-terminal region of the whole protein, cyanogen bromide fragments, tryptic and chymotryptic peptides and fragments produced by chemical cleavage after tryptophan residues. The protein consists of a single chain of 129 amino acid residues and has a Mr of 14647. While equine milk lysozyme has the essential features of a c(chick)-type lysozyme, there is only 51% sequence homology with human milk lysozyme and 50% with domestic hen egg white lysozyme. Some of the implications of the large number of differences are discussed.     

Potentiometric study of cytochrome c1aa3 from Thermus thermophilus

We have examined the redox behavior of the cytochrome c1aa3 complex from Thermus thermophilus. In potentiometric titrations the cytochrome c behaves as an independent center having n = 1 and E = 205 mV (NHE). Under the assumption that the individual centers equilibrate independently in this experiment, changes in the absorption band at 603 nm have been resolved into two components: cytochrome a (n = 1, Em = 270 mV, 60% spectral contribution) and cytochrome a3 (n = 2, Em = 360 mV, 40% spectral contribution). The n = 2 process was attributed to strong chemical coupling between cytochrome a3 and CuB. The enzyme was also titrated with a mixture of NADH and PMS, and the results are shown not to conform to a model of intramolecular equilibrium according to the equilibrium constants obtained from the potentiometric titration. It is suggested that a conformational equilibrium within the complex may control electron transfer between cytochromes a and a3.     

Serum selenium in danish Blood Bank donors

Biological Trace Element Research - Serum selenium concentration was determined over a full year in healthy donors from the Blood Bank at the municipal Hospital in Aarhus, Denmark. The age range of...     

Retention of cadmium in organs of the rat after a single dose of labeled cadmium-3-phytate

Because of the low safety factor estimated for the normal content of Cd in human foods, it is important to establish the influence of food constituents such as phytate on the bioavailability of this toxic metal. We studied the retention of radioactive¹⁰⁹Cd administered to rats as a chloride or a phytate in a single dose by stomach tube. The animals were fed either a normal rat chow containing 0.29% of phytate or a low phytate diet containing less than 0.1% phytate. Highly elevated levels of¹⁰⁹Cd were found only in the animals that were supplied with¹⁰⁹Cd as a chloride and had been fed the low phytate diet. In the animals supplied with¹⁰⁹Cd as a phytate, which had also received the low phytate diet, the levels of¹⁰⁹Cd in the intestine were as high as those in the group mentioned before, but the retentions in all other tissues resembled those of the respective groups fed the normal chow. The findings indicate that phytate is responsible for a considerable decrease in the intestinal absorption of Cd. Furthermore, it appears to exert an influence on the kinetics of Cd retention in the intestine.     

Macvicaria taksengi n. sp. (Digenea: Opecoelidae) in marine teleosts from Pinang,Malaysia

Summary A new species, Macvicaria taksengi (Opecoelidae: Plagioporinae), is described from the fishes Otolithes ruber and Sillago sihama from Pinang, Malaysia. It differs from most other members of the genus in the position of the ovary relative to the testes and the anterior position of the genital pore. A brief discussion on the Indo-West Pacific forms of the genus Macvicaria and related genera includes references to several new combinations: M. [Lebouria] isaitschikowi (Layman, 1930), M. [Plagioporus] sillagonis (Yamaguti, 1938), M. [Plagioporus] chrysophrys (Nagaty & Abdel Aal, 1969) and M. [Plagioporus (Plagioporus)] longisaccus (Fischthal & Kuntz, 1964).     

Micropropagation of the rare species Stylidium coroniforme and other Stylidium species

The number of plants in the gazetted rare species Stylidium coroniforme was increased through micropropagation. A method was first developed using the common species S. brunonianum. It was found that for both species, rapid propagation could be obtained by excising shoots from sterile seedlings and inducing shoot proliferation on Murashige and Skoog medium supplemented with 1 M BAP. Rooting was achieved using 1 M IBA and over 100 plants of each species were successfully established in soil. Leaf pieces could also be used to initiate cultures. In media with 20–25 M BAP and 1–5 M IBA, leaf pieces of S. brunonianum, S. piliferum, S. caricifolium and S. crassifolium produced adventitious buds, thus providing another method of micropropagation.     

Binding and degradation of proteoglycans by cultured arterial smooth muscle cells. II. Binding sites of proteoglycans on the cell surface

Exogenous proteoglycans stained for electron microscopy with colloidal gold and/or cuprolinic blue bind to the surface of cultured arterial smooth muscle cells at two different sites. (I) About 20% of the proteoglycans adsorbed to the cells from the culture medium interact as monomeric and multimeric proteoglycans with smooth or coated membrane areas. (II) The bulk of exogenous proteoglycans exhibits high affinity binding to cell membrane-associated 10 nm fibrils containing or being closely associated with fibronectin and to collagen. It is suggested that the self association of proteoglycans and their binding to the cell membrane and to cell surface-associated fibronectin and collagen are important for maintaining an appropriate micro-environment for the cultured cells.     

Alkylation-induced mono(ADP-ribosyl)-histones H1 and H2B. Hydroxylamine-resistant linkage in hepatoma cells

Treatment of hepatoma AH 7974 cells with dimethyl sulfate led to a marked accumulation in vivo of mono)ADP-ribosyl)-histone H1A, H1B, H1 and H2B, respectively. In these conjugates, most of the modifying groups were linked to the acceptor proteins by an 'unusual' bond not described so far for ADP-ribosyl histone conjugates. It resisted treatment with 3M hydroxylamine, 0.1M picrylsulfonate and mild alkali, which excluded a linkage through carboxyl or guanidino residues. The stability of these conjugates formed endogenously differed also from 'non-enzymic' histone H1 conjugates formed by incubation of free ADP-ribose with the histone. Histone-linked mono(ADP-ribosyl) residues synthesized in hepatoma cells in response to alkylation were located exclusively in the domains that interact with DNA, i.e. in the non-globular C-terminal tail of histone H1 and in the N-terminus of histone H2B. Besides poly(ADP-ribosyl)ation, the modification of histones by single ADP-ribose groups may represent an independent process to modulate DNA/histone interaction.