Ionic calcium and pH as predictors of stability of milk to UHT processing

This paper describes the use of pH and calcium ion electrodes for investigating factors affecting the heat stability of UHT milk with added calcium chloride. Calcium chloride was added to raw milk to manipulate ionic calcium and pH to within the range that may be typically encountered in raw milk of different compositions and microbial quality. Addition of only 5 mM calcium chloride was sufficient to induce considerable changes in pH, ionic calcium and ethanol stability and alter its stability to UHT treatment. There was a strong relationship between pH decrease and increase in ionic calcium when pH was reduced, whether by addition of calcium chloride or by acidification. Calcium chloride addition was found to increase sediment formation in UHT treated milk. However, sediment could be reduced by addition of stabilizers. Those most effective were ones which decreased ionic calcium and increased pH, such as trisodium citrate and disodium hydrogen phosphate. Sediment formation following UHT treatment was only slight for milk samples whose ethanol stability was greater than 80%.

Cellular and molecular investigations into the development of the pectoral girdle

The forelimbs of higher vertebrates are composed of two portions: the appendicular region (stylopod, zeugopod and autopod) and the less prominent proximal girdle elements (scapula and clavicle) that brace the limb to the main trunk axis. We show that the formation of the muscles of the proximal limb occurs through two distinct mechanisms. The more superficial girdle muscles (pectoral and latissimus dorsi) develop by the “In–Out” mechanism whereby migration of myogenic cells from the somites into the limb bud is followed by their extension from the proximal limb bud out onto the thorax. In contrast, the deeper girdle muscles (e.g. rhomboideus profundus and serratus anterior) are induced by the forelimb field which promotes myotomal extension directly from the somites. Tbx5 inactivation demonstrated its requirement for the development of all forelimb elements which include the skeletal elements, proximal and distal muscles as well as the sternum in mammals and the cleithrum of fish. Intriguingly, the formation of the diaphragm musculature is also dependent on the Tbx5 programme. These observations challenge our classical views of the boundary between limb and trunk tissues. We suggest that significant structures located in the body should be considered as components of the forelimb.