• Journal of Animal Science and Technology
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• v.50 no.5
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• pp.649-656
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• 2008

The current study was undertaken to investigate the mechanism of action of insulin-like growth factors (IGFs) on proliferation and differentiation of pig preadipocytes. The preadipocytes were isolated from the backfat of new-born female pigs and cultured in serum-deprived medium in the presence and absence of recombinant native IGFs or recombinant mutant IGFs that have reduced affinity for binding to both type-1 IGF receptors and insulin receptors. Fifty ng/ml of either IGF-I, [Leu60]IGF-I, IGF-Ⅱ or [Leu27]IGF-Ⅱ were included in the media in which preadipocytes were cultured for 4 days. IGF-I, [Leu60]IGF-I, IGF-Ⅱ and [Leu27]IGF-Ⅱ stimulated proliferation of pig preadipocytes by 39%, 8%, 25% and 2% respectively, as measured by increased numbers of cells. This indicates that both IGF-I and -II promote replication of pig preadipocytes by actions mediated either by type-1 IGF receptor or insulin receptor. IGF-I, [Leu60]IGF-I, IGF-Ⅱ and [Leu27]IGF-Ⅱ stimulated differentiation of pig preadipocytes by 50%, 17%, 37% and 30%, respectively, measured as glycerolphosphate dehydrogenase activity. Reducing the affinity of IGF-I for type-1 IGF receptors or insulin receptors significantly reduced the differentiation response. However, the differentiation response to [Leu27]IGF-II was not significantly different from the response to IGF-II. This shows that IGF-I and IGF-Ⅱ promote cell differentiation by different receptor-mediated mechanisms. IGF-II promotes differentiation of pig preadipocytes by actions that do not involve either type-1 IGF receptors or insulin receptors. These actions therefore appear to be mediated by binding of IGF-II to type-2 IGF receptors(also known as cation-independendent mannose-6-phosphate receptor[CIM6P/IGF2 receptor]). This is the first study to find evidence that IGF-II promotes differentiation of preadipocytes from any animal species by actions mediated by CIM6P/IGF2 receptors. In summary, this study shows that IGF-I and IGF-Ⅱ promote differentiation of pig preadipocytes by mechanisms that involve different cellular receptors.

• the MEAT Journal
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• s.36 summer
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• pp.41-60
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• 2009

This study was carried out to investigate the quality characteristics of brands pork: a crossbred between Korean native and wild pigs (Y), a commercial LYD breed fed with probiotics (J), and a commercial LYD fea without probiotics (M). The moisture and crude ash content of Y treated pork was higher than those for J and M brands, but the crude fat content of J pork was significantly lower (p<0.05) than Y and M brands. The moisture and crude fat contents of Y gilts were higher (p<0.05) than those of barrows. The pH values of Y gilts were higher (p<0.05) than those of gilts of J and M brands. The Land W values of Y pork were lower (p<0.05) than with J and M brands. The springiness value of J pork was significantly higher (p<0.05) than Y and M porks. The sensory scores of Y pork were higher than pork of J and M. The juiciness of gilts of M brands was higher (p<0.05) than for barrows. With regard to the fatty acid profiles among the pork loins, linoleic and arachidonic acid contents of Y pork were higher than with J and M, while the palmitic, pamitoleic, stearic, and oleic acid contents were lower. The saturated fatty acid (SFA) content of Y pork was lower than that for J and M ones, while the unsaturated fatty acids (USFA), essential fatty acids (FFA), USF/ASF A ratio, FFA/SFA ratio, and EFA/USFA ratio were higher. The stearic acid content of M barrows was higher (p<0.05) than that for gilts.