Two major regulatory steps in cholesterol synthesis by human renal cancer cells.

Two major mechanisms regulating cholesterol biosynthesis exist in a human renal cancer cell line, Caki-1. Caki-1 is a newly established cell line whose characteristics of rapid growth and active cholesterol synthesis qualify it as a potentially valuable tool for elucidation of regulatory mechanism of cholesterol synthesis and transport. In the absence of exogenous cholesterol, cholesterol is the dominant sterol arising from labeled acetate and mevalonate. As expected, in the presence of exogenous cholesterol, the conversion of acetate to cholesterol and the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.34) is markedly reduced and this inhibition is released when cholesterol is removed from the medium. An unexpected and possibly unique finding is the inhibition of the conversion of mevalonate to cholesterol in the presence of exogenous cholesterol. This second major control process results in the accumulation of squalene and may involve additional late steps in cholesterol biosynthesis or metabolism. The occurrence of two major mechanisms regulating cholesterol synthesis may be a unique property of renal cancer cells or a previously unrecognized characteristic of a variety of cultured cells.     

Rhodotorula matritense sp. nov., isolated from powdered red pepper (Capsicum frutescens L.)

A new species of Rhodotorula Harrison was recovered in May 1978 from Spanish powdered red pepper (Capsicum frutescens L.) in Madrid, Spain. It could not be identified with any hitherto described species of yeast and it was assigned to the genus Rhodotorula Harrison as representative of a new species on the bases of both its morphological and physiological characteristics, for which the name of Rhodotorula matritense is proposed.     

Respiratory responses to intravenous and intrapulmonary CO2 in awake dogs

Ventilatory responses to CO2 inhalation and CO2 infusion were compared in the awake dog. The CO2 was introduced directly into the systemic venous blood via a membrane gas exchanger in a femoral arteriovenous shunt circuit, and the extracorporeal blood flow, QX, was maintained constant at one of two rates: low, 0.5 l/min; or high, 2.0 l/min. A total of 13 experiments was performed in four dogs comprising 50 control and 25 inhalation and infusion observations at each of the two flow rates. Comparison of CO2-response curve slopes, S = delta V E/delta PaCO2, between CO2 inhalation and infusion showed no significant difference either within or between flow rates. The mean value of S for all conditions was 1.88 l/min per Torr with a 95% confidence interval of 1.66 -2.14. An independent additive ventilatory drive amounting to 28% of low-flow control VE was found at the highflow rate. We conclude that at constant blood flow the responses to both CO2 inhalation and infusion are hypercapnic and not significantly different.     

A simple procedure for resolution of Escherichia coli RNA polymerase holoenzyme from core polymerase.

The association constant, K_A, for myosin subfragment-1 binding to actin was measured as a function of ionic strength [KCl, LiCl, and tetramethylammonium chloride (TMAC)]and temperature by the method of time-resolved fluorescence depolarization. The following thermodynamic values were obtained from solutions of 0.20 × 10^?6m S-1, 1.00 × 10^?6m actin in 0.15 m KCl, pH 7.0, at 25 °C: ΔG ° = ?39 ± 1 kJ M^?1, ΔH⁰ = 44 ± 2 kJ M^?1 and $\text{ΔS}{}^0\text{= 0.28 ± 0.01 kJ}\text{M}{}^{\mathrm{?1}}{}^0\text{K}{}^{\mathrm{?1}}$. For measurements in KCl (0.05 to 0.60 m), In $\text{K}{}_{\mathrm{a}}\text{= ?8.36 (KCl)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. Thus, the binding is endothermic and strongly inhibited by high ionic strength. When KCl was replaced by LiCl or TMAC the ionic effects on the binding were cation specific. The nature of actin-(S-1) binding in the rigor state is discussed in terms of these results.     

Purification, characterization and some properties of diacetyl(acetoin) reductase from Enterobacter aerogenes

A new method, faster, milder and more efficient than the one previously described [Bryn, K., Hetland, O. & Stormer, F. C. (1971) Eur. J. Biochem, 18, 116-119], for purification of diacetyl(acetoin) reductase from Enterobacter aerogenes is proposed. The experiments carried out with the electrophoretically pure preparations obtained by this procedure show that the enzyme (a) produces L-glycols from the corresponding L-alpha-hydroxycarbonyls by reversible reduction of their oxo groups and also reduces the oxo group of uncharged alpha-dicarbonyls converting them into L-alpha-hydroxycarbonyls, and (b) is specific for NAD. This is a new enzyme for which we suggest the systematic name of L-glycol: NAD+ oxidoreductase and the recommended name of L-glycol dehydrogenase(NAD). The molecular mass, pI, affinity for substrates and pH profiles of this enzyme are also described.     

A new type of mitogenic factor produced by Streptococcus pyogenes.

A new type of mitogenic factor (protein) was purified from the culture supernatant of a strain of Streptococcus pyogenes by SP-Sephadex C-25 column chromatography, preparative isoelectric focusing and reversed-phase high-performance liquid chromatography. The purified factor, showing marked mitogenic activity in rabbit peripheral blood lymphocytes, gave a single-band staining for protein on SDS-PAGE. The molecular weight of the purified mitogenic factor was determined to be 25,370, which was different from those calculated from reported amino acid sequences deduced from 4 different nucleotide sequences of 3 kinds of streptococcal pyrogenic exotoxins (two SPEAs, SPEB and SPEC). The amino acid sequence of the N-terminal region of the purified mitogenic factor was determined to be Gln-Thr-Gln-Val-Ser-Asn-Asp-Val-Val-Leu-Asn-Asp-Gly-Ala-Ser-Lys-Tyr-Leu- Asn-Glu - Ala-, which was also different from the reported N-terminal sequences deduced from the 4 different nucleotide sequences. These data indicate that this mitogenic factor is distinct from the already described streptococcal pyrogenic exotoxins.     

Craniometric measurements of craniofacial malformations in the X-linked hypophosphatemic (Hyp) mouse on two different genetic backgrounds: C57BL/6J and B6C3H.

This study reports data on craniometric measurements in the X-linked hypophosphatemic (Hyp) mouse on two different genetic backgrounds: C57BL/6J and B6C3H. Heads of normal females "+/+," normal males "+/Y," heterozygous mutant females "Hyp/+," and hemizygous mutant males "Hyp/Y" for each genetic background were examined. Data were collected via skull measurements. On a C57BL/6J background, the neurocranium of mutants "Hyp/+" and "Hyp/Y" was shorter and slightly higher than in normal counterparts. On a B6C3H background, mutant mice "Hyp/+" and "Hyp/Y" were shorter in neurocranial length than in normal counterparts. Viscerocranial height was larger in "Hyp/Y" than in normal counterparts. No differences in neurocranial and mandibular height were found. Mutant mice on a C57BL/6J background were compared to mutant mice on a B6C3H background. No differences in neurocranial length were found. Cranial length was shorter in "Hyp/Y" on C57BL/6J than in "Hyp/+" on B6C3H. Facial length parameters were shorter in "Hyp/Y" on C57BL/6J than in "Hyp/Y" and "Hyp/+" mutant mice on B6C3H. Mandibular length was shorter in "Hyp/Y" on C57BL/6J than in "Hyp/+" on C57BL/6J and both mutant mice ("Hyp/Y" and "Hyp/+") on a B6C3H background. The results of this study indicate that craniofacial growth is less affected in mutant mice on a B6C3H genetic background than in mutant mice on a C57BL/6J genetic background.