Functional and association studies on the pig HMGCR gene, a cholesterol-synthesis limiting enzyme

The 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) is the rate-limiting enzyme in the biosynthesis of cholesterol. We have studied the role of the HMGCR gene in pig lipid metabolism by means of expression and structural analysis. We describe here the complete coding region of this gene in pigs and report two synonymous single nucleotide polymorphisms in the coding region. We have, additionally, studied the association of one of these polymorphisms (HMGCR:c.807A>C) with several lipid deposition- and cholesterol-related traits in a half-sib population generated from a commercial Duroc line, showing in some families a positive relationship of HMGCR:c.807A allele with serum low-density lipoprotein (LDL)-bound cholesterol and triglyceride levels, and also with intramuscular fat (IMF) content of gluteus medius muscle. We have also assessed the expression levels in muscle and in liver from 68 Duroc individuals corresponding to the most extreme animals for the analysed traits. Liver HMGCR expression correlated negatively with the serum high-density lipoprotein (HDL) levels, carcass lean percentage and stearic acid content, while muscle expression correlated also negatively with the carcass lean percentage, stearic and linoleic acids content, but showed a positive correlation with the serum lipid cholesterol (HDL, LDL and total cholesterol), IMF and muscle oleic and palmitic fatty acid content. With this information, we have performed an association analysis of expression data with lipid metabolism phenotypic levels and the HMGCR genotype. The results indicate that HMGCR expression levels in muscle are different in the two groups of pigs with extreme values for fat deposition and total cholesterol levels, and also between animals with the different HMGCR genotypes.     

Increasing the incubation temperature between embryonic day 7 and 10 has no influence on the growth and slaughter characteristics as well as meat quality of broilers

Avian embryogenesis can be manipulated by alteration of the temperature during incubation of the brooding egg. Investigations in turkeys showed that a higher temperature during early embryogenesis positively affects the myogenesis accompanied with a higher muscle fibre number (MFN). The aim of this study was to transfer this result to broiler and to investigate if an alteration of the temperature also affects the meat quality after slaughter of the birds. Therefore brooding eggs of the Cobb 500 broiler genetic were either incubated at 37.5°C during the whole incubation period (at normal temperature (NT)), or at 38.5°C during embryonic day (ED) 7 to 10 (at high temperature (HT)). After hatch the chicks were sexed and reared up to an age of 36 days in an experimental stable. Growth and feed conversion properties were determined during this period. After slaughter different meat quality characteristics as well as the muscle microstructure were analysed. The hatch rate and chick weight did not differ between the broiler of the NT and HT group. After 36 days the final body weights and the cumulative feed conversion rates were not different in the NT and HT groups. No differing results were obtained with regard to the slaughter, breast and leg weights of the NT and HT animals. Considering the gender of the animals no differences in the slaughter characteristics could be determined although the carcass and breast weights of the HT cocks were tendentially higher. The muscle fibre areas and MFNs in the breast muscles of the NT and HT cocks did not differ significantly and were in the range of the HT hens. Only the NT hens had significantly larger muscle fibres and less MFN than the other animals. With regard to the meat quality characteristics no clear differences of the pH, electrical conductivity (EC) and colour (L*a*b*) values were found. The L*a*b* values in the investigated breast muscles of all broilers usually increased during ageing. The increase of the incubation temperature had no impact on the hatch, growth, slaughter and meat quality characteristics of the broiler except for the tendentially higher carcass and breast weights of the HT cocks. However, the decrease of the fibre areas in the HT hens is an interesting effect of using a higher incubation temperature, which needs to be considered when implicating further investigations.     

The effects of stunning methods on product qualities in force-fed ducks and geese. 1. Carcass downgrading and meat quality

This study investigated the effects of various stunning methods on the quality of carcass and meat in ducks and geese force-fed for the production of French 'foie gras'. The ducks (n = 30 per group) were stunned with one of the following techniques: electrical stunning in a water bath (50 Hz AC, 130 mA, 4 s), head-only electrical stunning (50 Hz AC, 600 mA, 4 s), mechanical stunning (captive bolt) and controlled atmosphere stunning (CAS: phase 1, CO2 (40%)-O2 (30%)-N2 (30%), for 2 min followed by phase 2, CO2 > 85% in air, for 2 min). The same methods (except head-only stunning which was not applied) were used in geese (n = 40 per group). During the first 5 min after slaughter, the stunning techniques that did not kill the animals were associated with a high incidence of head movements (mechanical and electrical head-only stunning), convulsions and convulsive wing flapping (mechanical stunning), in both species. Consequently, the rate of post-mortem pH fall in breast muscle was enhanced and the meat was paler when measured at 24 h or 6 days post mortem (L*, a*, b* coordinates). In ducks, the animals stunned in the water bath showed the lowest bleeding efficiency, compared to the three other procedures. In geese, the mechanical stunning allowed the highest recovery of blood compared to the CAS and the water-bath methods. Meat texture assessed instrumentally and fluid losses during storage and processing were not affected by the stunning method in any species. Sensory analysis showed a higher score for bloody appearance of raw meat in ducks stunned with the methods that kill before neck cutting (water-bath and CAS). This effect was, however, not linked to the rate of bleeding. The sensory properties of cooked meat were not affected by the stunning method. In both ducks and geese, CAS was associated with the lowest rate of fractures of humeral bone but CAS-stunned geese showed the most engorged wing veins. Overall, these results show the positive effect of CAS on the appearance defects of carcass and meat of ducks and geese, and, on the contrary, they confirm the detrimental effects of water-bath stunning on these criteria. However, the incidences on meat sensory qualities were scarce.     

Milk and meat in our diet: good or bad for health?

Foods derived from animals are an important source of nutrients in the diet but there is considerable uncertainty about whether or not these foods contribute to increased risk of various chronic diseases. For milk in particular there appears to be an enormous mismatch between both the advice given on milk/dairy foods items by various authorities and public perceptions of harm from the consumption of milk and dairy products, and the evidence from long-term prospective cohort studies. Such studies provide convincing evidence that increased consumption of milk can lead to reductions in the risk of vascular disease and possibly some cancers and of an overall survival advantage from the consumption of milk, although the relative effect of milk products is unclear. Accordingly, simply reducing milk consumption in order to reduce saturated fatty acid (SFA) intake is not likely to produce benefits overall though the production of dairy products with reduced SFA contents is likely to be helpful. For red meat there is no evidence of increased risk of vascular diseases though processed meat appears to increase the risk substantially. There is still conflicting and inconsistent evidence on the relationship between consumption of red meat and the development of colorectal cancer, but this topic should not be ignored. Likewise, the role of poultry meat and its products as sources of dietary fat and fatty acids is not fully clear. There is concern about the likely increase in the prevalence of dementia but there are few data on the possible benefits or risks from milk and meat consumption. The future role of animal nutrition in creating foods closer to the optimum composition for long-term human health will be increasingly important. Overall, the case for increased milk consumption seems convincing, although the case for high-fat dairy products and red meat is not. Processed meat products do seem to have negative effects on long-term health and although more research is required, these effects do need to be put into the context of other risk factors to long-term health such as obesity, smoking and alcohol consumption.     

Chimeric types of chromosome X in bottom-fermenting yeasts

Aim:  To determine the structure of the chimeric chromosome X of bottom-fermenting yeasts.
Methods and Results:  Eight cosmid clones carrying DNA from chromosome X of bottom-fermenting yeasts were selected by end-sequencing. Four of the cosmid clones had Saccharomyces cerevisiae (SC)-type and Saccharomyces bayanus (SB)-type chimeric ends, two had SC-type ends and two had SB-type ends. Sequencing revealed that the bottom-fermenting yeast strains in this study had four types of chromosome X: SC–SC, SC–SB, SB–SC and SB–SB. The translocation site in the chimeric chromosome is conserved among bottom-fermenting yeast strains, and was created by homologous recombination within a region of high sequence identity between the SC-type sequence and the SB-type sequence.
Conclusions:  Existing bottom-fermenting yeast strains share a common ancestor in which the chimeric chromosome X was generated.
Significance and Impact of the Study:  The knowledge gained in this study sheds light on the evolution of bottom-fermenting yeasts.     

Phenomorphology and ecomorphological characters of Maytenus senegalensis L. Shrublands in the Iberian Peninsula: A comparison with other Mediterranean plant communities

This work sets out to establish ecomorphological and phenomorphological patterns in the constituent flora of an Iberian Maytenus senegalensis plant community in order to relate it with or separate it from other types of Mediterranean vegetation. This plant community contains tall shrubs, scrubs, palms and vines of a variety of families. Typical ecomorphological adaptations to the Mediterranean climate were observed in the community studied: an abundance of thorny species or species with tomentose leaves and photosynthetic stems, small leaves and a high presence of species with organs capable of post-fire regeneration. However, the community also showed hybrid characteristics between scrubland (predominantly malacophyllous leaves lasting 9 months on average and low biomass) and tall shrubland communities (predominance of phanerophytes up to 3 m in height, predominantly smooth bark, periodical reposition of leaves, mean lifespan of plants 25 years and mainly fleshy fruit). The community also presents an outstanding quantity of amphiphytes (29%). From a phenological point of view, the formation of buds in winter, flowering in spring, summer–autumn seed dispersal and leaf shedding in summer are typical of other Mediterranean communities, while fructification and growth lasting three seasons, as in the case of Maytenus shrubland, is not. The RVA phenophasic index (balance between reproductive and vegetative phenophases) with values of 0.4–2 shows an intermediate value between typical shrubland (0.3–1) and forest community (1–2) values. The APC index (period of phenophasic activity of the community) differentiates it from others, since it remains at 100% for seven months, three of which are winter months. Phenophasic patterns (overlapping, or not, of flower bud formation, flowering and growth) show how similar M. senegalensis shrubland is to forests because of the absence of phenophase pattern type A (characteristic in open-scrublands); in addition, we have detected a new pattern (type G), still regarded as exclusive to M. senegalensis. As regards the existence of coenomorphs (group of species with similar morpho-functional strategies), the studied community showed much greater diversity than other communities studied to date, with an Strategies Richness index (SRi) of 0.79 (11 groups covering the 14 species existing), pointing to the co-existence of a great variety of eco-phenomorphological strategies, each with a successful response to the same ecological conditions. Finally, some of the species in the community, e.g. Asparagus horridus, Chamaerops humilis and M. senegalensis, stand out because of their unique ecomorphological and phenological characteristics.     

Predator–prey interactions between Dugesia gonocephala and free-living nematodes

1. Three groups of laboratory experiments clarified the role of nematodes as a potential food resource for the triclad Dugesia gonocephala. The first group measured the functional response of adult D. gonocephala feeding on juvenile or adult Caenorhabditis elegans. The feeding rates of D. gonocephala on adult and juvenile C. elegans followed a type II functional response. The maximum number of adult nematodes and juvenile nematodes eaten by a single D. gonocephala individual within 3 h was 94 and 197 nematodes, respectively. 2. A second group of microcosm experiments investigated the effect of D. gonocephala on the density and the vertical distribution of a nematode community in fine sand. The following treatments were performed: (i) microcosms with 400 nematodes and (ii) microcosms with 400 nematodes and one D. gonocephala. After 5 days, nematodes as a group, as well as the dominant species Tobrilus pellucidus and Trischistoma monohystera, showed no significant difference in vertical patterns between the treatments with and without D. gonocephala. 3. The third group of experiments determined whether grain size of the sediment (sand, fine gravel and coarse gravel) altered the ability of D. gonocephala to consume adult C. elegans. Sand and fine gravel reduced the predation effectiveness of D. gonocephala by 100%, whereas the predator consumed nematodes in coarse gravel (19 nematodes within 3 h).     

A resource-based conceptual model of plant diversity that reassesses causality in the productivity–diversity relationship

Biogeographical studies frequently reveal positive correlations between species richness and estimates of environmental water and/or energy. A popular interpretation of this relationship relates the supply of water and energy to productivity, and then, in turn, to richness. Productivity–diversity theories are now legion, yet none has proved sufficiently intuitive to gain broad acceptance. Like productivity, heterogeneity is known to influence diversity at fine spatial scales, yet the possibility that richness might relate to water–energy dynamics at coarse spatial scales via a heterogeneity‐generating mechanism has received little attention. In this paper we outline such a conceptual model for plants that is internally consistent and testable. We believe it may help to explain the capacity of environments receiving different inputs of water and energy to support variable numbers of species at a range of spatial scales, the pervasive correlation between productivity and richness, some exceptions to the productivity–diversity relationship, the form of productivity–diversity curves and the link between richness and environmental ‘harshness’. The model may also provide an answer to one of the most venerable puzzles in the field of diversity studies: why high inputs of water and energy correspond to more species rather than simply more individuals.     

滇产与日产松茸的IGS1-RFLP比较分析

应用Cfr13I限制性内切酶对采自于云南省16个市县的127个松茸子实体进行了IGS1-RFLP比较分析,发现126个松茸子实体属于A类型,来自大理白族自治州剑川县的1例(TF89)为C类型。通过对A类型的IGS1序列分析发现产自云南的松茸有一个CTTT的简单重复,滇产松茸IGS1序列差异不明显。滇产松茸的IGS1-RFLP与日产松茸的主要类型十分相似,两地松茸可能是同源的。     

The effect of peroxyacetic acid-based sanitizer, heat and ultrasonic waves on the survival of Clostridium estertheticum spores in vitro

AIM: To determine the effect of selected physical and chemical treatments on the survival of 'blown pack'-causing Clostridium estertheticum. METHODS AND RESULTS: The study investigated the survival of the spores of 'blown pack'-causing C. estertheticum following the four treatments, which include: heat alone, ultrasound followed by heat treatment, peroxyacetic acid (POAA)-based sanitizer followed by heat treatment and POAA sanitizer followed by heat treatment in the presence of 20% animal fat. No C. estertheticum survivors were recovered in spore preparations that underwent either of the two treatments with the sanitizer, resulting in the inactivation of 4 to 5 log CFU ml(-1) of spores. Similarly, no survivors were detected in spore preparations that were treated with the sanitizer for 5 min at room temperature without further heat treatment. When using heat alone and ultrasound followed by heat treatment, complete spore inactivation did not occur for spores heated at times and temperature combinations other than 240 s at 100 degrees C. CONCLUSIONS: POAA sanitizer used with or without heat is capable of in vitro inactivation of at least 4 log CFU ml(-1)C. estertheticum spores. SIGNIFICANCE AND IMPACT OF THE STUDY: The data generated in the study provide background information for controlling 'blown pack'-causing clostridia on dressed carcasses and in meat plant environment.