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°

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

Character of the diatom assemblage spanning a depositional transition in the Eastern Equatorial Pacific Ocean at 6.6 Ma

Approximately 6.6 million years ago in the Eastern Equatorial Pacific a large increase in biogenic mass accumulation rates (MARs) occurred. This increased level of biogenic mass accumulation persisted until about 4.4 Ma at which time levels returned to those similar to before the transition at 6.6 Ma. The exact nature of the change that facilitated this transition in biogenic MARs, however, was not understood. Here we present the results of a study which characterizes the diatom assemblage spanning the depositional transition at 6.6 Ma from sediments taken from ODP Hole 850B. A close inspection of lithology reveals a clear change in lithology from a diatom nannofossil ooze to a nannofossil diatom ooze at 6.6 Ma. This transition is immediately followed by the occurrence of laminated diatom ooze (LDO). Diatom absolute abundance data reveals three levels of productivity associated with pre-transitional, post-transitional, and LDO formational sediments. An increase in the absolute abundance of Thalassionema nitzschioides was the major contributor to the formation of post-transitional, and LDO sediments. The known ecological preferences of this species indicate an overall increase in nutrient availability followed by sporadic changes in nutrient availability. These changes in nutrient availability could be associated with the establishment, or increase in strength, of an upwelling cell and/or the increase in nutrients made available via upwelling due to a shoaling of the thermocline

Ecology of Audubon\u27s Shearwaters (Puffinus lherminieri) at San Salvador, Bahamas

The Audubon\u27s Shearwater (Pqffinus lherminieri), nearly pantropical in distribution, remains a poorly studied species. The subspecies P. l. lherminieri is endemic to the West Indies region. An estimated 5,000 pairs inhabit the Caribbean, but there has been a substantial decline with many colonies becoming extirpated. It is thought that as many as 3,000 pairs (60% of the West Indian population) nest in the Bahamas. In May and June of 2000, I collected data on shearwater demographics, colony site selection, burrow microhabitat, chick behavior and the effect of moonlight on the onset of calling of the Audubon\u27s Shearwaters nesting on the satellite cays of San Salvador Island, Bahamas. The population of nesting shearwaters on the cays was estimated at 107 pairs. The size of the rock over a shearwater burrow and the percent of rock within a one-meter radius of the burrow entrance were two factors that distinguished between the burrow microhabitats of the different cays. The size of the colonies on individual cays was proportional to the availability of rocky habitat. Chick behavior varied ,significantly with time of day and age. Adults returned from offshore foraging areas to feed their young on 70% of the nights. Measures of chick activity were greater at night than by day and increased during the three weeks of the study. The amount of ambient light on any given night did not significantly affect the time shearwaters arrived at the colony (i.e., started calling). The detailed behavior of chick feeding bouts was described, and data on morphometrics are also reported. The information gathered in this study is integral to understanding the biology of the Audubon\u27s Shearwater and aiding in the development of an effective conservation plan

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

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