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Indigenous resources of the Asian pig population are less defined and only rarely compared with European breeds. In this study, five indigenous pig breeds from Viet Nam (Mong Cai, Muong Khuong, Co, Meo, Tap Na), two exotic breeds kept in Viet Nam (Large White, Landrace), three European commercial breeds (Pietrain, Landrace, Large White), and European Wild Boar were chosen for evaluation and comparison of genetic diversity. Samples and data from 317 animals were collected and ten polymorphic microsatellite loci were selected according to the recommendations of the FAO Domestic Animal Diversity Information System (DAD-IS; http://www.fao.org/dad-is/). Effective number of alleles, Polymorphism Information Content (PIC), withinbreed diversity, estimated heterozygosities and tests for Hardy-Weinberg equilibrium were determined. Breed differentiation was evaluated using the fixation indices of Wright (1951). Genetic distances between breeds were estimated according to Nei (1972) and used for the construction of UPGMA dendrograms which were evaluated by bootstrapping. Heterozygosity was higher in indigenous Vietnamese breeds than in the other breeds. The Vietnamese indigenous breeds also showed higher genetic diversity than the European breeds and all genetic distances had a strong bootstrap support. The European commercial breeds, in contrast, were closely related and bootstrapping values for genetic distances among them were below 60%. European Wild Boar displayed closer relation with commercial breeds of European origin than with the native breeds from Viet Nam. This study is one of the first to contribute to a genetic characterization of autochthonous Vietnamese pig breeds and it clearly demonstrates that these breeds harbour a rich reservoir of genetic diversity.

Selection based on DNA markers is most useful for traits that are hard to measure and have low heritability. It allows earlier and more accurate selection, increasing short- and medium-term selection response, and may aid in targeting genotypes for specific production environments or markets. The use of genotypic information in breeding programmes for within-breed selection will generally have limited extra benefit, unless selection based on phenotype is difficult or advanced reproductive technologies are used. Novel reproductive technologies boost reproductive rates of breeding animals and may allow reproduction at juvenile ages. The benefit arises from increased selection intensity, as well as from increased selection accuracy due to larger families and decreased generation interval, as higher reproductive rates result in lower optimal ages for breeding animals. Increased reproductive rates and early selection rely more on between-family selection and potentially decrease effective population size, therefore increasing inbreeding. Selection needs to be optimized with respect to inbreeding and merit. Extra benefit from scenarios with unlimited use of reproductive technologies is restricted by the need to maintain genetic diversity. Benefits from marker assisted selection are higher in breeding programmes that use reproductive technologies, as the value of providing information about genotype is more beneficial for selection of young animals before they have a phenotype. Moreover, genotype information exploits variation within families, which is beneficial in breeding programmes where loss of genetic diversity is to be controlled. In developing countries, use of genotype information is likely to be most useful in marker assisted introgression programmes, where valuable genes are introgressed from one breed into another. A large variety of genetic resources in developing countries exists across breeds and populations, and utilization and management of this variation might greatly benefit from gene technologies.

The effect of pregnancy on oestrogen receptor (ER) and progesterone receptor (PR) endometrial expression in heifers was studied. Holstein heifers were not inseminated (controls, n = 8) or inseminated (n = 21). Endometrial biopsies were taken at Day 17 from the uterine horn ipsilateral to the corpus luteum. Hourly samples were taken on the day of the biopsy in 12 animals (controls = 4 and inseminated = 8) to analyze 15-ketodihydro-PGF_2α (PGFM) and progesterone concentrations. Pregnancy determined by ultrasonography diagnosed 6 pregnant cows. The uterine biopsy increased PGFM concentrations, which remained high for 2 to 4 hours, followed by a transient decrease in progesterone concentrations, but the procedure neither provoked luteolysis nor blocked pregnancy. PGFM concentrations were higher in cyclic than in pregnant cows. No differences in PR mRNA expression were observed among groups, but ER mRNA in pregnant heifers tended to be lower than controls, suggesting that this pathway is implicated in maintenance of pregnancy.

The improvement of livestock productivity and the preservation of their genetic diversity to allow breeders to select animals adapted to environmental changes, diseases and social needs, require a detailed inventory and genetic characterization of domesticated animal breeds. Indeed, in developing countries, the notion of breed is not clearly defined, as visual traits are often used and characterization procedures are often subjective. So it is necessary to upgrade the phenotypic approach using genetic information. At CIRDES, a regional centre for subhumid livestock research and development, such studies have been conducted. This paper focuses on cattle breed inventory in seven countries of West Africa as a tool for genetic research on cattle improvement. Data collection was done using a bibliographical study, complemented by in situ investigations. According to phenotypic description and concepts used by indigenous livestock keepers, 13 local cattle breeds were recognized: N’dama, Kouri, the Baoule-Somba group, the Lagoon cattle group, zebu Azawak, zebu Maure, zebu Touareg, zebu Goudali, zebu Bororo, zebu White Fulani, zebu Djelli, zebu Peuhl soudanien and zebu Gobra (Toronke). Nine exotic breeds, (American Brahman, Gir, Girolando, Droughtmaster, Santa Gertrudis, Holstein, Montbéliarde, Jersey and Brown Swiss) and five typical cross-breeds (Holstein x Goudali; Montbé liarde x Goudali; Holstein x Azawak; Brown Swiss x Azawak; and Brown Swiss x zebu peuhl soudanien) were also found. From this initial investigation, the areas of heavy concentration of herds and the most important breeds were described. The review has also indicated the necessity for a balance between improving livestock productivity and the conservation of trypanotolerant breeds at risk of extinction in West Africa.

All animals, including humans, are adapted to life in a microbial world. Large populations of micro-organisms inhabit the gastrointestinal tract of all animals and form a closely integrated ecological unit with the host. This complex, mixed, microbial culture can be considered the most metabolically adaptable and rapidly renewable organ of the body, which plays a vital role in the normal nutritional, physiological, immunological and protective functions of the host animal. Bacteria have traditionally been classified mainly on the basis of phenotypic properties. Despite the vast amount of knowledge generated for ruminal and other intestinal ecosystems using traditional techniques, the basic requisites for ecological studies, namely, enumeration and identification of all community members, have limitations. The two major problems faced by microbial ecologists are bias introduced by culture-based enumeration and characterization techniques, and the lack of a phylogenetically-based classification scheme. Modern molecular ecology techniques based on sequence comparisons of nucleic acids (DNA or RNA) can be used to provide molecular characterization while at the same time providing a classification scheme that predicts natural evolutionary relationships. These molecular methods provide results that are independent of growth conditions and media used. Also, using these techniques, bacteria can be classified and identified before they can be grown in pure culture. These nucleic acid-based techniques will enable gut microbiologists to answer the most difficult question in microbial ecology: namely, describing the exact role or function a specific bacterium plays in its natural environment and its quantitative contribution to the whole. However, rather than replacing the classical culture-based system, the new molecular-based techniques can be used in combination with the classical approach to improve cultivation, speciation and evaluation of diversity. The study of microbial ecology in gut ecosystems involves investigation of the organisms present (abundance and diversity), their activity (usually determined in vitro , but in vivo activity or expression of activity is really required), and their relationship with each other and the host animal (synergistic and competitive interactions). This entails the study and measurement of many types of interactions, both beneficial and competitive. Traditionally, media for isolation of bacteria from natural environments are basically of two types: those that simulate the habitat in broad terms, i.e. habitat-simulating and non-selective media; and those designed to enumerate and isolate bacteria of a particular type or from a specific biochemical niche, i.e. niche-simulating or functional or nutritional group analysis. A third type, less important in the ecological sense, does not simulate the habitat, is often highly selective and is used to isolate specific bacterial groups. Specific nutritional types of bacteria may be isolated by the use of enrichment media. This type of medium, basically a refinement of the habitat-simulating medium, is widely used in environmental microbiology and has been applied with some success to the gut ecosystem. Although estimates of microbial number rely on culture techniques, microscopic examination is a most useful technique for evaluating the efficacy of other enumeration approaches. The combination of microscopy with specific phylogenetic stains or fluorescent antibodies enables bacteria to be specifically detected and enumerated in mixed populations. The introduction of genetic-based technologies, and in particular those relating to 16S rRNA typing, are rapidly replacing conventional detection and enumeration methods in studies of the mammalian intestinal tract. Although molecular techniques promise a fuller and more accurate description of the true diversity, structure and dynamics of complex microbial communities than the present culturing studies, each technique suffers from its own experimental bias and selectivity. Different methods used for direct molecular detection are reviewed in the paper. Attention is given to molecular characterization of complex communities; in particular, the application of molecular fingerprinting techniques to examine diversity and community structure in complex gut bacterial communities. Denaturing or temperature gradient gel electrophoresis (DGGE/TGGE) methods have been successfully applied to the analysis of human, pig, cattle, dog and rodent intestinal populations. In future, genomics technologies will provide gut microbial ecologists with their best opportunity for a complete or global analysis of the molecular mechanisms involved in metabolism and regulation within the bacterial community and between host and resident microbes. Molecular microbial techniques have been widely and successfully used to study microbial diversity in environmental microbiology but have had limited application in the gastrointestinal ecosystem.

The detection and characterization of specific nucleic acids of medico-veterinary pathogens have proven invaluable for diagnostic purposes. Apart from hybridization and sequencing techniques, polymerase chain reaction (PCR) and numerous other methods have contributed significantly to this process. The integration of amplification and signal detection systems, including on-line real-time devices, have increased speed and sensitivity and greatly facilitated the quantification of target nucleic acids. They have also allowed for sequence characterization using melting or hybridization curves. Rugged portable real-time instruments for field use and robotic devices for processing samples are already available commercially. Various stem-loop DNA probes have been designed to have greater specificity for target recognition during real-time PCR. Various DNA fingerprinting techniques or post amplification sequencing are used to type pathogenic strains. Characterization according to DNA sequence is becoming more readily available as automated sequencers become more widely used. Reverse hybridization and to a greater degree DNA micro-arrays, are being used for genotyping related organisms and can allow for the detection of a large variety of different pathogens simultaneously. Non-radioactive labelling of DNA, especially using fluorophores and the principles of fluorescence resonance energy transfer, is now widely used, especially in real-time detection devices. Other detection methods include the use of surface plasmon resonance and MALDI-TOF mass spectrometry. In addition to these technological advances, contributions by bioinformatics and the description of unique signatures of DNA sequences from pathogens will contribute to the development of further assays for monitoring presence of pathogens. An important goal will be the development of robust devices capable of sensitively and specifically detecting a broad spectrum of pathogens that will be applicable for point-of-care use. Advances in biosensors, the development of integrated systems, such as lab-on-a-chip devices, and enhanced communications systems are likely to play significant future roles in allowing for rapid therapeutic and management strategies to deal with disease outbreaks.

New strategies to genetically manipulate the genomes of several important animal pathogens have been established in recent years. This article focuses on the reverse genetics techniques, which enables genetic manipulation of the genomes of non-segmented negative-sense RNA viruses. Recovery of a negative-sense RNA virus entirely from cDNA was first achieved for rabies virus in 1994. Since then, reverse genetic systems have been established for several pathogens of medical and veterinary importance. Based on the reverse genetics technique, it is now possible to design safe and more effective live attenuated vaccines against important viral agents. In addition, genetically tagged recombinant viruses can be designed to facilitate serological differentiation of vaccinated animals from infected animals. The approach of delivering protective immunogens of different pathogens using a single vector was made possible with the introduction of the reverse genetics system, and these novel broad-spectrum vaccine vectors have potential applications in improving animal health in developing countries.

The continuous interactions between host and viruses during their co-evolution have shaped not only the immune system but also the countermeasures used by viruses. Studies in the last decade have described the diverse arrays of pathways and molecular targets that are used by viruses to elude immune detection or destruction, or both. These include targeting of pathways for major histocompatibility complex class I and class II antigen presentation, natural killer cell recognition, apoptosis, cytokine signalling, and complement activation. This paper provides an overview of the viral immune-evasion mechanisms described to date. It highlights the contribution of this field to our understanding of the immune system, and the importance of understanding this aspect of the biology of viral infection to develop efficacious and safe vaccines.