The Effect of Ergosterol on the Desaturation Of 14C-Labeled Oleic Acid in Tetrahymena

The ciliated protozoan Tetrahymena pyriformis-Strain W desaturated 14C-labeled fatty acid substrate in both sterol supplemented (ergosterol) and nonsupplemented cultures. Cis-octadecenoic acid (14C-9-18:1), when added to the medium during the log phase of growth, was incorporated into the cells and also desaturated at the Δ6 and Δ12 positions. The 14C labeled substrate and products, linoleate (9,12-18:2) or linolenate (6,9,12-18:3) were recovered and separated by silver-nitrate Unisil column chromatography. Initially, recovery of 14C compounds varied widely when expressed as the percent of total counts per minute recovered from column chromotography, and a variety of procedural modifications were required before a reproducibly significant effect of the foreign sterol on desaturation of substrate was demonstrated. Addition of ergosterol to the growth medium of Tetrahymena leads to incorporation of the foreign sterol within cell membranes and supression of synthesis of the native compound tetrahymanol, as well as to changes in the fatty acid compositions of several major classes of membrane lipid. Alteration of fatty acid composition is thought to represent a regulatory mechanism whereby optimum membrane fluidity is maintained when the slightly dissimilar foreign sterol is incorporated into the phospholipid bilayer of the membranes. The present study, using several different conditions of growth temperature, culture size and ergosterol concentrations, is an attempt to provide evidence supporting a regulatory role for membrane-bound sterol. The regulatory mechanism hypothesized is allosteric modification of an enzyme or enzymes involved in the synthesis of fatty acids contained in membrane phospholipids by the membrane-bound sterol. Such a mechanism could account, at least in part, for the balance between sterol and fatty acid content of membranes. The data presented here show that a statistically significant decrease in desaturation of 14C-labeled 9-18:1 can be demonstrated in Tetrahymena cell cultures whose membranes contain the foreign sterol ergosterol when compared to cell cultures not receiving sterol supplementation when growth temperature is maintained at 20°

The Effect of Ergosterol on the Desaturation Of 14C-Labeled Oleic Acid in Tetrahymena

The ciliated protozoan Tetrahymena pyriformis-Strain W desaturated 14C-labeled fatty acid substrate in both sterol supplemented (ergosterol) and nonsupplemented cultures. Cis-octadecenoic acid (14C-9-18:1), when added to the medium during the log phase of growth, was incorporated into the cells and also desaturated at the Δ6 and Δ12 positions. The 14C labeled substrate and products, linoleate (9,12-18:2) or linolenate (6,9,12-18:3) were recovered and separated by silver-nitrate Unisil column chromatography. Initially, recovery of 14C compounds varied widely when expressed as the percent of total counts per minute recovered from column chromotography, and a variety of procedural modifications were required before a reproducibly significant effect of the foreign sterol on desaturation of substrate was demonstrated. Addition of ergosterol to the growth medium of Tetrahymena leads to incorporation of the foreign sterol within cell membranes and supression of synthesis of the native compound tetrahymanol, as well as to changes in the fatty acid compositions of several major classes of membrane lipid. Alteration of fatty acid composition is thought to represent a regulatory mechanism whereby optimum membrane fluidity is maintained when the slightly dissimilar foreign sterol is incorporated into the phospholipid bilayer of the membranes. The present study, using several different conditions of growth temperature, culture size and ergosterol concentrations, is an attempt to provide evidence supporting a regulatory role for membrane-bound sterol. The regulatory mechanism hypothesized is allosteric modification of an enzyme or enzymes involved in the synthesis of fatty acids contained in membrane phospholipids by the membrane-bound sterol. Such a mechanism could account, at least in part, for the balance between sterol and fatty acid content of membranes. The data presented here show that a statistically significant decrease in desaturation of 14C-labeled 9-18:1 can be demonstrated in Tetrahymena cell cultures whose membranes contain the foreign sterol ergosterol when compared to cell cultures not receiving sterol supplementation when growth temperature is maintained at 20°

A Racial Impact Analysis of HB 1075/SB 201

The economic and social consequences of untreated (or under-treated) substance abuse among minors are significant. This report provides a racial impact analysis of HB 1075/SB 201, legislation approved in the 2012 General Assembly session that seeks to improve access and use of substance and alcohol services by minors. In short, this policy could go a long way to ensure that families are properly educated about these life-changing (and life-saving) programs; however our analysis raises concerns related to cultural competency that may serve to undermine the legislation’s goal. Virginia is incredibly diverse and its communities vary widely with its assets and risks. In this vein, we offer concrete recommendations to maximize the policy’s racial equity. Our analysis also sheds light on the ongoing challenge Virginia’s state agencies have had to address cultural competency within its services. Additional research is necessary to determine what service gaps may exist, which would increase or decrease the racial equity impact. By answering these questions, Virginia will be better prepared to further reduce alcohol and substance abuse by all minors

Seventy years of sex education in Health Education Journal: a critical review

This paper examines key debates and perspectives on sex education in Health Education Journal (HEJ), from the date of the journal’s first publication in March 1943 to the present day. Matters relating to sexuality and sexual health are revealed to be integral to HEJ’s history. First published as Health and Empire (1921 – 1942), a key purpose of the journal since its inception has been to share information on venereal disease and its prevention within the UK and across the former British Empire. From 1943 to the present day, discussions on sex education in the newly-christened HEJ both reflect and respond to evolving socio-cultural attitudes towards sexuality in the UK. Changing definitions of sex education across the decades are examined, from the prevention of venereal disease and moral decline in war-time Britain in the 1940s, to a range of responses to sexual liberation in the 1960s and 1970s; from a focus on preventing sexually-transmitted infections, teenage pregnancy and HIV in the 1980s, to the provision of sexual health services alongside sex education in the 2000s. Over the past 70 years, a shift from prevention of pre-marital sexual activity to the management of its outcomes is apparent; however, while these changes over time are notable, perhaps the most striking findings of this review are the continuities in arguments for and against the discussion of sexual issues. After more than 70 years of debate, it would seem that there is little consensus concerning motivations for and the content of sex education

Imaging Polarimeter Arrays for Near-Millimeter Waves

An integrated-circuit antenna array has been developed that images both polarization and intensity. The array consists of a row of antennas that lean alternately left and right, creating two interlaced sub-arrays that respond to different polarizations. The arrays and the bismuth bolometer detectors are made by a photoresist shadowing technique that requires only one photolithographic mask. The array has measured polarization at a wavelength of 800 µm with an absolute accuracy of 0.8° and a relative precision of 7 arc min. and has demonstrated nearly diffraction-Iimited resolutiort of a 20° step in polarization

Millimeter-wave diode-grid phase shifters

Monolithic diode grids have been fabricated on 2-cm square gallium-arsenide wafers with 1600 Schottky-barrier varactor diodes. Shorted diodes are detected with a liquid-crystal technique, and the bad diodes are removed with an ultrasonic probe. A small-aperture reflectometer that uses wavefront division interference was developed to measure the reflection coefficient of the grids. A Phase shift of 70° with a 7-dB loss was obtained at 93 GHz when the bias on the diode grid was changed from -3 V to 1 V. A simple transmission-line grid model, together with the measured low-frequency parameters for the diodes, was shown to predict the measured performance over the entire capacitive bias range of the diodes, as well as over the complete reactive tuning range provided by a reflector behind the grid, and over a wide range of frequencies form 33 GHz to 141 GHz. This shows that the transmission-line model and the measured low-frequency diode parameters can be used to design an electronic beam-steering array and to predict its performance. An electronic beam-steering array made of a pair of grids using state-of-the-art diodes with 5-Ω series resistances would have a loss of 1.4 dB at 90 GHz

Millimeter-Wave Diode-Grid Frequency Doubler

Monolithic diode grid were fabricated on 2-cm^2 gallium-arsenide wafers in a proof-of-principle test of a quasi-optical varactor millimeter-wave frequency multiplier array concept. An equivalent circuit model based on a transmission-line analysis of plane wave illumination was applied to predict the array performance. The doubler experiments were performed under far-field illumination conditions. A second-harmonic conversion efficiency of 9.5% and output powers of 0.5 W were achieved at 66 GHz when the diode grid was pumped with a pulsed source at 33 GHz. This grid had 760 Schottky-barrier varactor diodes. The average series resistance was 27 Ω, the minimum capacitance was 18 fF at a reverse breakdown voltage of -3 V. The measurements indicate that the diode grid is a feasible device for generating watt-level powers at millimeter frequencies and that substantial improvement is possible by improving the diode breakdown voltage

Array concepts for solid-state and vacuum microelectronics millimeter-wave generation

The authors have proposed that the increasing demand for contact watt-level coherent sources in the millimeter- and submillimeter-wave region can be satisfied by fabricating two-dimensional grids loaded with oscillators and multipliers for quasi-optical coherent spatial combining of the outputs of large numbers of low-power devices. This was first demonstrated through the successful fabrication of monolithic arrays with 2000 Schottky diodes. Watt-level power outputs were obtained in doubling to 66 GHz. In addition, a simple transmission-line model was verified with a quasi-optical reflectometer that measured the array impedance. This multiplier array work is being extended to novel tripler configurations using blocking barrier devices. The technique has also been extended to oscillator configurations where the grid structure is loaded with negative-resistance devices. This was first demonstrated using Gunn devices. More recently, a 25-element MESFET grid oscillating at 10 GHz exhibited power combining and self-locking. Currently, this approach is being extended to a 100-element monolithic array of Gunn diodes. This same approach should be applicable to planar vacuum electron devices such as the submillimeter-wave BWO (backward wave oscillator) and vacuum FET