Priorities for Pig Research in Southeast Asia and the Pacific to 2010

Livestock Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Coat colour variants of village pigs in Papua New Guinea

A preliminay description and genetic analysis of coat colour variation in Papua New Guinea village pigs is presented. Data were obtained from a series of deliberate matings and from surveys of coat coloration in two villages. A number of pigmentary variations caused by alleles at the Agouti, Extension and Brown loci were found and are described, including a possible new allele at the Brown locus (Bk) causing brown spots on the basic red background colour. The segregations observed in the deliberate matings can be interpreted in terms of two alleles at the Agouti (Aw and a) and two at the Extension loci (E + and Ep). Results from the village surveys show a high incidence of agouti phenotypes [Aw], relative to black [a], and a very low incidence of white designs (belt or points). These results suggest a still small genetic influence of exotic pigs in the villages, in spite of deliberate distribution, provided that the allele causing black colour (a) is present in the native Papuan stock. The allele Ep (spotted) giving black patched on red (or secondarily white) background may also be considered as a part of the native stock. The results are consistent with a hypothesis concerning an early arrival of pigs in Papua New Guinea relatively soon after domestication, followed by a period of isolation.Il s’agit d’une description et d’une étude génétique préliminaires de la variation colorée des porcs villageois de Papouasie Nouvelle-Guinée. Les données proviennent d’une série de croisements expérimentaux et d’observations dans deux villages. Les variations observées sont attribuées à des allèles contrôlant la pigmentation proprement dite aux loci Agouti, Extension et Brun avec, pour ce dernier locus, un possible mutant Bk induisant des taches brunes sur fond rouge. Les ségrégations observées dans les croisements expérimentaux ont été interprétées en terme de biallélismes en Agouti (Aw et a) et en Extension (E+ et Ep). Les résultats des enquêtes villageoises montrent une fréquence élevée du phénotype Agouti [Aw] par rapport au phénotype noir [a] et une fréquence très basse des dessins blancs (ceinture ou points blancs). Ces résultats suggèrent que l’influence génétique résultant de l’introduction de races exotiques dans les villages est encore très faible en dépit de distributions encouragées, à condition que l’on admette que l’allèle a pour la couleur noire est un élément du stock autochtone. L’allèle Ep (domino) qui donne des taches noires sur fond rouge (ou secondairement blanc) peut aussi être considéré comme faisant partie du stock indigène papou. Ces résultats s’accordent avec l’hypothèse d’une arrivée précoce du porc dans l’île, relativement peu de temps après sa domestication. Ensuite il y a eu une période d’isolement

Static and dynamic pre-stressing of metal discs.

In order to develop a technique of controlled prestressing of metal components, mild steel discs were dynamically loaded using explosives. Subsequently, mild steel discs of similar dimensions were loaded statically. The following loading conditions were studied:(i) at fixed radius and varying load (ii) at varying radial positions and fixed load (iii) at constant load and fixed radius but varying outer diameter of disc (dynamic tests only).For the dynamically loaded discs, residual radial stresses have been obtained by an experimental technique, based on strain gauge readings, which permitted the estimation of the residual stresses at the incremental radius of the successively cut sections of the discs for both outer and inner sections. Further analysis of the experimental results has produced values for the residual radial and hoop stress at radii close to the explosive loading radius. Correlation from results obtained from the statically loaded discs was provided by strain gauges fixed at varying fixed radii on each-loaded disc. The experimental analysis for the statically loaded discs was of simpler form than that required for the dynamically loaded discs.In order to establish the validity of the method for estimating the residual radial stresses, certain other experimental measurements have been made viz: planedeformation, hardness, microstructural examination and buckling tests. A theoretical model based on plastic deformation of the loaded annulus has been developed which requires an estimation of the energy transferred from the loading ring or annulus to the surface of the disc. In the majority of cases, agreement between experimental and theoretical values of residual radial and hoop stress have been found in both magnitude and sign. A further theoretical approach was applied using finite element technique to validate the equivalent stress values obtained from the experimental results of the statically loaded discs. Comparison of the results again showed good agreement in magnitude and sign

Immunotherapy Targeting Pathological Tau Conformers in a Tangle Mouse Model Reduces Brain Pathology with Associated Functional Improvements

Immunotherapies for various neurodegenerative diseases have recently emerged as a promising approach for clearing pathological protein conformers in these disorders. This type of treatment has not been assessed in models that develop neuronal tau aggregates as observed in frontotemporal dementia and Alzheimer's disease. Here, we present that active immunization with a phosphorylated tau epitope, in P301L tangle model mice, reduces aggregated tau in the brain and slows progression of the tangle-related behavioral phenotype. Females had more tau pathology than males but were also more receptive to the immunotherapy. The tau antibodies generated in these animals recognized pathological tau on brain sections. Performance on behavioral assays that require extensive motor coordination correlated with tau pathology in corresponding brain areas, and antibody levels against the immunogen correlated inversely with tau pathology. Interestingly, age-dependent autoantibodies that recognized recombinant tau protein but not the immunogen were detected in the P301L mice. To confirm that anti-tau antibodies could enter the brain and bind to pathological tau, FITC-tagged antibodies purified from a P301L mouse, with a high antibody titer against the immunogen, were injected into the carotid artery of P301L mice. These antibodies were subsequently detected within the brain and colocalized with PHF1 and MC1 antibodies that recognize pathological tau. Currently, no treatment is available for clearing tau aggregates. Our present findings may lead to a novel therapy targeting one of the major hallmarks of Alzheimer's disease and frontotemporal dementia

Retrieval of Context-Associated Memory is Dependent on the Cav3.2 T-Type Calcium Channel

Among all voltage-gated calcium channels, the T-type Ca2+ channels encoded by the Cav3.2 genes are highly expressed in the hippocampus, which is associated with contextual, temporal and spatial learning and memory. However, the specific involvement of the Cav3.2 T-type Ca2+ channel in these hippocampus-dependent types of learning and memory remains unclear. To investigate the functional role of this channel in learning and memory, we subjected Cav3.2 homozygous and heterozygous knockout mice and their wild-type littermates to hippocampus-dependent behavioral tasks, including trace fear conditioning, the Morris water-maze and passive avoidance. The Cav3.2 −/− mice performed normally in the Morris water-maze and auditory trace fear conditioning tasks but were impaired in the context-cued trace fear conditioning, step-down and step-through passive avoidance tasks. Furthermore, long-term potentiation (LTP) could be induced for 180 minutes in hippocampal slices of WTs and Cav3.2 +/− mice, whereas LTP persisted for only 120 minutes in Cav3.2 −/− mice. To determine whether the hippocampal formation is responsible for the impaired behavioral phenotypes, we next performed experiments to knock down local function of the Cav3.2 T-type Ca2+ channel in the hippocampus. Wild-type mice infused with mibefradil, a T-type channel blocker, exhibited similar behaviors as homozygous knockouts. Taken together, our results demonstrate that retrieval of context-associated memory is dependent on the Cav3.2 T-type Ca2+ channel