Search

Aim The genetic impact of Quaternary climatic fluctuations on mountain endemic species has rarely been investigated. The Pyrenean rock lizard ( Iberolacerta bonnali) is restricted to alpine habitats in the Pyrenees where it exhibits a highly fragmented distribution between massifs and between habitats within massifs. Using mitochondrial DNA markers, we set out: (1) to test whether several evolutionary units exist within the species; (2) to understand how the species persisted through the Last Glacial Maximum and whether the current range fragmentation originates from distribution shifts after the Last Glacial Maximum or from more ancient events; and (3) to investigate whether current mitochondrial diversity reflects past population history or current habitat fragmentation. Location The Pyrenees in south-western France and northern Spain. Methods We used variation in the hypervariable left domain of the mitochondrial control region of 146 lizards collected in 15 localities, supplemented by cytochrome b sequences downloaded from GenBank to cover most of the species' distribution range. Measures of population genetic diversity were contrasted with population isolation inferred from topography. Classical ( F-statistics) and coalescence-based methods were used to assess the level of gene flow and estimate divergence time between populations. We used coalescence-based simulations to test the congruence of our genetic data with a scenario of simultaneous divergence of current populations. Results Coalescence-based analyses suggested that these peripheral populations diverged simultaneously at the end of the last glacial episode when their habitats became isolated on mountain summits. High mitochondrial diversity was found in peripheral, isolated populations, while the populations from the core of the species' range were genetically impoverished. Where mitochondrial diversity has been retained, populations within the same massif exhibited high levels of genetic differentiation. Main conclusions As suggested for many other mountain species, the Pyrenean rock lizard survived glacial maxima through short-distance range shifts instead of migration or contraction in distant southern refugia. Most of the main Pyrenean range has apparently been re-colonized from a single or a few source populations, resulting in a loss of genetic diversity in re-colonized areas. As a result, current levels of intra-population mitochondrial diversity are better explained by post-glacial population history than by current habitat fragmentation. Genetic population differentiation within massifs implies severe reduction in female-mediated gene flow between patches of habitats. [ABSTRACT FROM AUTHOR]

Between April 2003 and March 2005, 113 outbreaks of histomonosis were recorded in standard turkey farms in France, and 15 cases were recorded in turkey breeding centres. Most of the cases were in north-west France, the principal farming area for turkeys. The majority of the cases occurred during the hottest months, from April to September. Large numbers of cases occurred among birds from four to eight weeks of age, but there were some cases in three-week-old birds and some in birds up to 17 weeks of age. In most of the standard turkey flocks the mortality was less than loper cent, but it was above 30 per cent in nearly 20 per cent of the outbreaks. In the breeding flocks, the average mortality was 60!2 per cent. The size of the flocks, the sex of the birds and the age at which the first clinical signs appeared did not seem to influence the mortality. [ABSTRACT FROM AUTHOR]

1. This experiment evaluated the influence of the rate of post mortem pH fall on the processing ability of turkey meat. 2. Four hundred and twenty male turkeys from a selected pure line (grand-parental female line, BUT Ltd) were slaughtered at 16 weeks of age in a commercial plant and pH was measured in the Pectoralis superficialis (PS) and Ilio tibialis (IT) muscles, at 20 min post mortem. Three groups of PS muscle differing in pH[sub 20] and two groups of IT muscle differing in pH[sub 20] were constituted and processed as cured-cooked white meat and turkey ham, respectively. 3. The technological yield was lower in the groups showing the lowest pH[sub 20 ](97·4% at pH[sub 20] 5·90 vs 98·6 and 98·3% at pH[sub 20] 6·24 and 6·55, respectively, for white meat and 97·2% (pH[sub 20] 6·28) vs 98·3% (pH[sub 20] 6·56) for turkey hams). The groups showing the lowest pH[sub 20] also showed higher drip loss in commercially packed products. 4. Acceptability tests of processed products were carried out in the commercial plant. Texture and taste of white meat were better in the highest pH group but the overall impression was similar in the lowest and the highest pH groups (mean scores of 4·2 and 4·1, respectively), due to better colour in the former (mean scores of 4·4 for the lowest pH[sub 20] group vs 4·0 and 3·9 for the medium and highest pH[sub 20] groups, respectively). 5. For turkey hams, the meat processed from the highest pH group got the best score for all items. [ABSTRACT FROM AUTHOR]

Reports developments related to animal, farming and environment systems. Use of pen space by broiler chickens reared in commercial conditions; Study on the aspects of the behavior and health of animals; Typology of activity bouts in broiler chicken.

1. A standard (FG, fast-growing), a black local or 'label', type (SG, slow-growing) turkey line, and the crossbreed between these two lines were compared for muscle post-mortem metabolism and related meat quality traits. 2. Ninety male turkeys (30 of each genetic type) were raised under the same experimental conditions until slaughter at 16 weeks of age. 3. Live weights at 16 weeks of age differed significantly (7·8, 6·0 and 4·2 kg, for the FG, crossbred and SG lines, respectively). Collagen content of Pectoralis superficialis (PS) muscle was higher in SG birds than in the other two types. 4. The rate of post-mortem glycogen depletion and lactate accumulation in PS and Ilio tibialis (IT) muscles were similar in the 3 lines, as were the rate and extent of post-mortem pH fall in PS muscle. In IT muscle, however, SG birds showed a slight but significantly faster pH decline. 5. Colour measurements indicated a paler breast muscle and a higher degree of myoglobin oxidation in SG birds at 24 h post mortem , than in both other lines. But these differences had disappeared after 4 and 7 d post mortem 6. SG birds showed higher drip loss and instrumentally-assessed toughness in breast muscle, compared with crossbred and FG birds. FG birds, however, had the lowest yield of breast meat after curingcooking. 7. No marked differences in post-mortem metabolism were found between the three lines. However, differences in water-holding capacity of fresh and cured-cooked meat suggest that factors other than the rate and extent of post-mortem pH fall may contribute to the respective characteristics of these lines. [ABSTRACT FROM AUTHOR]

Although most telomere repeat sequences are found at the ends of chromosomes, some telomeric repeat sequences are also found at intrachromosomal locations in mammalian cells. Several studies have found that these interstitial telomeric repeat sequences can promote chromosome instability in rodent cells, either spontaneously or following ionizing radiation. In the present study we describe the extensive cytogenetic analysis of three different human cell lines with plasmids containing telomeric repeat sequences integrated at interstitial sites. In two of these cell lines, Q18 and P8SX, instability has been detected in the chromosome containing the integrated plasmid, involving breakage/fusion/bridge cycles or amplification of the plasmid DNA, respectively. However, the data suggest that the instability observed is characteristic of the general instability in these cell lines and that the telomeric repeat sequences themselves are not responsible. Consistent with this interpretation, the chromosome containing an integrated plasmid with 500 bp of telomeric repeat sequences is highly stable in the third cell line, SNG28, which has a relatively stable genome. The stability of the chromosome containing the integrated plasmid sequences in SNG28 makes this an excellent cell line to study the effect of ionizing radiation on the stability of interstitial telomeric sequences in human cells. [ABSTRACT FROM AUTHOR]