The extensive use of a limited number of elite bulls in cattle breeding can lead to rapid spread of recessively inherited disorders. A recent example is the globally distributed syndrome Complex Vertebral Malformation (CVM), which is characterized by misshapen and fused vertebrae around the cervico-thoracic junction. Here, we show that CVM is caused by a mutation in the Golgi-resident nucleotide-sugar transporter encoded by SLC35A3. Thus, the disease showed complete cosegregation with the mutation in a homozygous state, and proteome patterns indicated abnormal protein glycosylation in tissues of affected animals. In addition, a yeast mutant that is deficient in the transport of UDP-N-acetylglucosamine into its Golgi lumen can be rescued by the wild-type SLC35A3 gene, but not by the mutated gene. These results provide the first demonstration of a genetic disorder associated with a defective SLC35A3 gene, and reveal a new mechanism for malformation of the vertebral column caused by abnormal nucleotide-sugar transport into the Golgi apparatus.

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Differential scanning calorimetry was used to investigate denaturation characteristics of pork muscle proteins from carriers and noncarriers of the RN-gene. Pork from RN-carriers deviated from noncarriers in maximum denaturation temperatures and denaturation enthalpy, with proteins of RN-carriers being the most heat-labile. Correlation studies on the results showed that water-holding capacity was significantly correlated to changes in enthalpy of the population mainly representing myosin tails and sarcoplasmic proteins (p < 0.001). Finally, the influence of ultimate pH and preheating on thermal characteristics of porcine muscle proteins was studied. Myosin tails and sarcoplasmic proteins were most sensitive to pH changes, while myosin heads were most sensitive to preheating simulating stress-induced temperature increases.

The AMP-activated protein kinase (AMPK) plays a key role in the regulation of energy metabolism in eukaryotic cells acting as a metabolic sensor. In its activated form AMPK inhibits ATP consuming pathways and stimulates ATP generating pathways. A dominant mutation, denoted RN(-), in the porcine PRKAG3 gene, encoding the regulatory gamma3 subunit of AMPK, results in hyperaccumulation of glycogen in glycolytic skeletal muscle cells. To study the effects of this mutation on protein expression patterns in skeletal muscle, comparative proteome analysis of muscle samples from 12 animals (6 rn (+)/rn (+) and 6 RN(-)/rn (+)) was performed. The major finding of the proteome analysis was that the key enzyme in the synthesis of glycogen, UDP-glucose pyrophosphorylase, was significantly up-regulated in RN(-) carriers. This observation was subsequently supported by studies of enzyme activity and Northern blot analysis. Furthermore, the expression patterns of enzymes related to glycolysis and the citric acid cycle were also affected. Our data suggests that hyperaccumulation of glycogen mediated by the RN(-) mutation is due to an increased synthesis of glycogen.

We have grown expanded populations of epidermal growth factor (EGF)-responsive mouse striatal precursor cells and subsequently co-cultured these with primary E14 rat ventral mesencephalon. The aim of these experiments was to induce dopaminergic (DA) neuronal phenotypes from the murine precursors. While no precursor cell-derived neurons were induced to express tyrosine hydroxylase (TH), there was a dramatic 30-fold increase in the survival of rat-derived TH-positive neurons in the co-cultures. The effect was not explicable solely in terms of total plating density, and was accompanied by a significantly enhanced capacity for [3H]dopamine uptake in the co-cultures compared to rat alone cultures. The present data show that, although primary rat E14 mesencephalic cells are incapable of inducing the development of DA neurons from EGF-responsive mouse neural precursor cells, such precursors will differentiate into cells capable of enhancing the survival and overall functional efficacy of primary embryonic dopamine neurons.