Biodiversity of 52 chicken populations assessed by microsatellite typing of DNA pools

In a project on the biodiversity of chickens funded by the European Commission (EC), eight laboratories collaborated to assess the genetic variation within and between 52 populations from a wide range of chicken types. Twenty-two di-nucleotide microsatellite markers were used to genotype DNA pools of 50 birds from each population. The polymorphism measures for the average, the least polymorphic population (inbred C line) and the most polymorphic population (Gallus gallus spadiceus) were, respectively, as follows: number of alleles per locus, per population: 3.5, 1.3 and 5.2; average gene diversity across markers: 0.47, 0.05 and 0.64; and proportion of polymorphic markers: 0.91, 0.25 and 1.0. These were in good agreement with the breeding history of the populations. For instance, unselected populations were found to be more polymorphic than selected breeds such as layers. Thus DNA pools are effective in the preliminary assessment of genetic variation of populations and markers. Mean genetic distance indicates the extent to which a given population shares its genetic diversity with that of the whole tested gene pool and is a useful criterion for conservation of diversity. The distribution of population-specific (private) alleles and the amount of genetic variation shared among populations supports the hypothesis that the red jungle fowl is the main progenitor of the domesticated chicken.     

Uptake of immunisation in district health authorities in England

The uptakes of immunisation in the district health authorities in England were studied for the years 1983-5. Multiple regression analysis showed that the factors significantly associated with a low uptake of immunisation were mainly related to social conditions, particularly overcrowding of households and population density. Of the service factors, high proportions of elderly and singlehanded general practitioners and high average list sizes were also associated with a low uptake of immunisation in some of the analyses.The results suggest that the measures outlined in the government''s white paper on improving primary health care services are likely to lead to improved uptakes of immunisation. If, however, the uptakes of immunisation are used as a measure of standards of the services provided they should first be adjusted to control for variations in social conditions, and the quality of vaccination data would have to be improved.     

Gastric emptying in soldiers during and after field exercise in the heat measured with the [13C]acetate breath test method

The effects of exercise on gastric emptying remain controversial, with some workers reporting that heavy exercise inhibits it to varying degrees whereas others report no effects up to an intensity of 70% maximal oxygen consumption (O_2max). The state of hydration of the subjects and the environmental conditions may influence the rate of gastric emptying during exercise. To understand further the effects of a 3-h, 16-km walk/run carrying 30 kg of equipment under field conditions at 39°C, we estimated gastric emptying using a [¹³C]acetate breath test method. Breath samples were collected at intervals after giving 150 mg of [¹³C]acetate. The effects of giving a standard volume (530 ml) of water or dextrose (7.5 g · 100 ml⁻¹) with electrolytes or fructose/corn solids (7.5 g · 100 ml⁻¹) at rest before exercise were compared with those of exercise and of recovery after exercise with or without extra fluids (400 ml each 20 min). At rest, after a standard 530-ml load, gastric emptying times [mean (SE)] were: 37 (2) min (water), 46 (3) min (dextrose/electrolytes) and 47 (5) min (fructose/corn solids) and were significantly slower (P < 0.05) than those occurring after extra fluid ingestion, i.e. 32 (3), 39 (2) and 41 (3) min respectively. After a standard 530-ml load, emptying times during exercise were almost identical to those at rest but, during exercise, extra fluid speeded up gastric emptying more than at rest to 24 (2), 26 (1) and 27 (5) min (P < 0.05) respectively. During resting recovery without extra fluids, gastric emptying was significantly slowed to 60 (2), 71 (5) and 78 (3) min, respectively. Although emptying times during recovery from exercise with extra fluid were faster [49 (6), 55 (2) and 58 (4) min, respectively], they were still slower than before exercise. The results suggest that: (1) extra fluid increases gastric emptying more during exercise than at rest, and (2) gastric emptying during resting recovery from exercise is slower than at rest before exercise whether or not fluid has previously been taken. Accepted: 17 June 1996     

Population density of the Réunion Grey White-eye Zosterops borbonicus within the summit ecosystems of Réunion,Mascarene Islands

Assessing population density is crucial for studying the ecology and evolutionary biology of species as well as for conservation purposes. Here we used point count methods to infer population density in a single-island endemic passerine bird, the Réunion Grey White-eye Zosterops borbonicus, that displays striking evidence of differentiation at a small spatial scale. Population density was estimated at 5.17 birds ha^?1 (CL 4.85–5.50), a value somewhat higher than previously believed. This estimation provides the first detailed estimation of bird population density in the vulnerable summit ecosystems of Réunion and will possibly allow a better understanding of the evolutionary causes of this plumage colour variation.     

Multiple‐stressor effects on stream invertebrates: a mesocosm experiment manipulating nutrients,fine sediment and flow velocity

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Muscle fibre typing in the human pharyngeal constrictors and oesophagus: the effect of ageing

Myosin-ATPase fibre typing revealed type 1 predominance (81%) in the human oesophagus and type 2 predominance in the pharyngeal constrictor (33% type 1) indicative of widely different functions. Fibre diameters were around 30 microns, significantly smaller than skeletal muscle. No significant change in mean fibre diameter or percentage of fibre type was seen with ageing, but atrophy and compensatory hypertrophy led to an increased variability in fibre diameters with age. No sex differences were observed, probably reflecting a similar usage of these muscles and contrasting with skeletal muscle.     

Plasma neurotensin release and gastric emptying in the dumping syndrome

Seventy-three patients were studied after ingesting a liquid glucose meal, tagged with ¹¹³Indium. Nineteen of these patients were awaiting surgery for their duodenal ulcer, while 54 were studied postoperatively, 25 of whom experienced troublesome postprandial (dumping) symptoms in their daily lives. The radioactive marker emptied significantly faster in the symptomatic patients than in the symptomfree, pre and post-operative groups (initial emptying rate 3.45 ± 0.23, compared with 1.16 ± 0.19 and 1.27 ± 0.15% fall in counts/min respectively; p < 0.01). Initial (20 min) rises in the plasma concentrations of neurotensin-like immunoreactivity measured during the test correlated significantly with the rate of gastric emptying in all patients, being greatest in patients with dumping symptoms. Physiological concentrations of neurotensin have been shown to delay gastric emptying. The excessive rise in plasma neurotensin-like immunoreactivity in patients with dumping symptoms, presumably occuring as a result of the rapid passage of nutrients to the neurotensin-rich ileum, may possibly have a compensatory role in slowing further emptying from the stomach.     

Molecular evidence for the rapid propagation of mouse t haplotypes from a single, recent, ancestral chromosome

Mouse t haplotypes are variant forms of chromosome 17 that exist at high frequencies in worldwide populations of two species of commensal mice. To determine both the relationship of t haplotypes to each other and the species within which they exist, 35 representative t haplotypes were analyzed by means of 10 independent molecular probes, including five DNA clones and five polypeptide spots identified by means of two- dimensional gel electrophoresis. All of the tested haplotypes were found to share restriction fragments and polypeptide spots that are absent in mice carrying wild-type forms of chromosome 17. This observation provides the first direct evidence that all of the known t haplotypes are descendents of a single ancestral chromosome. The absence of variation among t haplotypes could mean that this ancestral chromosome existed relatively recently, in which case it would be necessary to postulate introgressions of t haplotypes across species lines to explain their presence in both Mus domesticus and M. musculus. Alternatively, it is possible that the ancestral chromosome existed prior to the split between M. domesticus and M. musculus and that, by chance, our probes fail to detect polymorphisms that exist among the t haplotypes. A further result of our analysis is the characterization of a partial t haplotype in a wild population of Israeli mice.