Net nearest neighbor analysis (NNNA) summarizes non-compensated dinucleotides within gene sequences.

Motivation: Net Nearest Neighbor Analysis (NNNA) measures a previously unexamined aspect of dinucleotide frequency-the non-compensated, non-repetitive dinucleotides in a sequence. Non-compensated dinucleotides are those in excess of their corresponding reverse dinucleotides.

Results: NNNA regards dinucleotides as vector quantities, making it possible to summarize any sequence as a group of circuits and tags.

Influence of magnesium ions on heat shock and ethanol stress responses of Saccharomyces cerevisiae.

This study has highlighted the role of magnesium ions in the amelioration of the detrimental effects of ethanol toxicity and temperature shock in a winemaking strain of Saccharomyces cerevisiae. Specifically, results based on measurements of cellular viability and heat shock protein synthesis together with scanning electron microscopy have shown that, by increasing the bioavailability of magnesium ions, physiological protection is conferred on yeast cells. Elevating magnesium levels in the growth medium from 2 to 20 mM results in repression of certain heat shock proteins following a typical heat shock regime (30-42 degrees C shift).

The effects of cigarette smoking on negative priming.

Nicotine administration has been found to enhance performance on tasks of selective attention. It has been proposed that efficient attentional filtering depends on the successful inhibition of distracting information. In the work reported here, a negative priming paradigm was adopted to test whether smoking enhanced the inhibition of irrelevant information.

Synchronization of yeast cell populations.

The study of synchronous populations of yeast cells has provided a wealth of information into regulatory aspects of the eukaryotic cell division cycle. Synchronized yeast cultures may also have potential benefit when exploiting yeasts in biotechnology. This paper provides an overview of the methods which have been used in the synchronization of cell division in budding and fission yeasts.

Variability in the size of the nucleus in spermatozoa from Houbara bustards, Chlamydotis undulata undulata.

Semen collected from 3-year-old male Houbara bustards contained large proportions (6-40%) of spermatozoa with large nuclei. In these spermatozoa, the length of the nucleus was up to twice the mean length of the nucleus in normal spermatozoa. The lengths of the acrosome, midpiece and flagella were all normally distributed, but the length of the nucleus formed a bimodal distribution.

Changes to water repellence of soil caused by the growth of white-rot fungi: studies using a novel microcosm system.

A microcosm system is described which permits assessment of the progressive growth of filamentous fungi through soil. We report on its application to measure the effects of Coriolus versicolor and Phanerochaete chrysosporium upon the sorptivity and water repellence of a mineral soil, measured using a miniature infiltration device. Both fungal species caused moderate sub-critical repellence.

Sperm cell mediated transgenesis: a review.

Transgenesis would be greatly streamlined if sperm cells could be used as transgene vectors. Attempts to 'force' sperm cells to take up transgenes may be more worthy of further study than 'autouptake' attempts. However, thorough proof of its effectiveness will be required if sperm cell-mediated gene transfer is to be accepted, given the evolutionary implications associated with the possibility of sperm cells being able to transfer exogenous DNA.

Biotechnological implications of the interactions between magnesium and calcium.

At the biochemical level, magnesium and calcium are known to act antagonistically towards each other. For example, many enzymes whose activities critically depend on sufficiency of intracellular magnesium, especially transphosphorylases, will be detrimentally affected by small increments in levels of cellular calcium ions. Growth of cells, cell division cycle progress and intermediary metabolism are also absolutely dependent on the bioavailability of magnesium, which can be compromised if excess calcium is present.

Temperature-dependent inhibition of motility in spermatozoa from different avian species.

This study demonstrates that the pattern of temperature-dependent inhibition of chicken sperm motility at 40 degrees C in vitro, and its release by calcium, is also found in drake spermatozoa and, partially, in turkey spermatozoa. However, no such temperature-dependent inhibition was found in spermatozoa from Japanese quail and Houbara bustard, for which physiological levels of calcium at 40 degrees C had an inhibitory and no effect on sperm motility, respectively. Thus, on the basis of this evidence on the regulation of avian sperm motility in vitro, the hypothesis that oviducal sperm storage tubules might immobilise spermatozoa by providing a calcium-free environment in vivo does not appear to be universally applicable to all species of birds.

A novel assay for the distribution of pyrithione biocides in bacterial cells.

Sodium pyrithione and zinc pyrithione (NaPT and ZnPT, respectively) are widely used as cosmetic preservatives and metal chelating agents. They are commonly assayed using thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). However, a simple quantitative colorimetric assay has not been previously reported for these compounds.

Pyrithione biocides as inhibitors of bacterial ATP synthesis.

Sodium pyrithione and zinc pyrithione (NaPT and ZnPT, respectively) are widely used as cosmetic preservatives and general antimicrobial agents. They have been shown to be active against fungal cell walls, associated membranes and bacterial transport processes. Investigations were undertaken into the effect of these antimicrobial agents on substrate catabolism and intracellular ATP levels using an oxygen electrode and luciferin-laciferase technology, respectively.

Pyrithione biocide interactions with bacterial phospholipid head groups.

Sodium pyrithione and zinc pyrithione (NaPT and ZnPT, respectively) are antimicrobial agents widely used in both the cosmetics and fuel industries. They are also utilized in the mining industry because of their metal chelating properties. They have been shown to depolarize membrane electropotential in fungi and are also known to inhibit fungal and bacterial substrate transport processes.

Evaluation of semen from individual male domestic fowl by assessment of sperm: perivitelline interaction in vitro and in vivo.

1. Spermatozoa in semen samples from 8 individual male domestic fowls were shown to have a differential and characteristic ability to hydrolyse holes in the inner perivitelline layer from laid eggs in an in vitro assay. 2.

Quantification of a sperm-egg interaction for estimating the mating efficiency of broiler breeder flocks.

1. The frequency distribution of points of sperm hydrolysis (or holes) produced per unit area of the inner perivitelline layer was examined in samples of approximately 60 laid eggs, taken on the same day from each of 19 flocks of broiler breeder hens. 2.

Misunderstanding between knowledge engineers and domain experts: a re-evaluation of the use of induction for medical expert systems.

The effectiveness of an induction algorithm for making decisions was investigated using a complete set of diagnoses and corresponding outcomes for all possible distinct cases of thyroid disorders. Investigation of both diagnoses and outcomes followed a late discovery of a misunderstanding between the knowledge engineers and the expert. The knowledge engineers had erroneously equated the expert's terms 'diagnosis' and 'outcome'.

Quantitative aspects of sperm:egg interaction in chickens and turkeys.

Spermatozoa embedded in the outer perivitelline layer and points of hydrolysis (holes) produced by spermatozoa in the inner perivitelline layer of chicken and turkey eggs were found to be evenly distributed and linearly correlated (r = 0.80 for both species) throughout the layers from most regions of the egg, except from those directly over the germinal disc, in which there were more holes. In turkey eggs there appeared to be relatively fewer perivitelline spermatozoa, since many had degenerated beyond recognition.

Characterization and application of an avian in vitro spermatozoa-egg interaction assay using the inner perivitelline layer from laid chicken eggs.

The inner perivitelline layer, separated from laid chicken eggs, was investigated as readily available material for studying the spermatozoa-egg interaction in vitro. This layer was found to have a similar response to hydrolysis by spermatozoa as the inner perivitelline layer from ovulated and follicular ova, in terms of the numbers of points of hydrolysis made by spermatozoa during a 5 min incubation at 40 degrees C. Initiation of hydrolysis of the inner perivitelline layer was found to occur within 2.

Accumulation of magnesium ions during fermentative metabolism in Saccharomyces cerevisiae.

When cells of Saccharomyces cerevisiae were grown aerobically under glucose-repressed conditions, ethanol production displayed a hyperbolic relationship over a limited range of magnesium concentrations up to around 0.5 mM. A similar relationship existed between available Mg2+ and ethanol yield, but over a narrower range of Mg2+ concentrations.

The effect of removing surface-associated proteins from viable chicken spermatozoa on sperm function in vivo and in vitro.

When chicken spermatozoa were diluted in isotonic or hypertonic solutions, sperm surface-associated proteins were lost to the medium, quantitatively more protein being lost to medium of higher osmotic strength. The proteins which were removed from the spermatozoa were also found within chicken seminal plasma, but at different relative concentrations, thus demonstrating selective association of only certain seminal proteins with the spermatozoa. The removal of these proteins occurred with only minimal damage to the spermatozoa, as judged by sperm motility, ATP content and ability to exclude eosin.

Demonstration that the removal of sialic acid from the surface of chicken spermatozoa impedes their transvaginal migration.

Staining of ejaculated chicken spermatozoa with lectin from FITC-conjugated Limulus polyphemus indicated a uniform distribution of terminal sialic acid residues on surface-associated glycoproteins throughout all regions of the spermatozoa. Treatment of spermatozoa with neuraminidase resulted in complete disappearance of this lectin affinity without any visible change in the viability of spermatozoa, as indicated by assessment in vitro of their motility, ATP content and ability to exclude eosin. Neuraminidase-treated spermatozoa were also severely limited in their ability to populate the uterovaginal sperm storage tubules after intravaginal insemination, although they were able to perform this function as well as untreated control spermatozoa after insemination directly into the uterovaginal region.

Why I want to be a psychiatric nurse: constructing an identity through contrasts with general nursing.

The justification of psychiatric specialization among undergraduate nursing students is examined. The data highlight how students are able to produce a positive view of their initial entry into nursing and then later create a positive and distinctive specialist occupational identity through negative comparisons with general nursing. Their experience in both psychiatric and general settings is drawn upon to add credibility to their claims.