Differentiation of fiber types in skeletal muscle from the sequential inactivation of myofibrillar actomyosin ATPase during acid preincubation

A method is described for identifying fiber types of skeletal muscle from several mammalian species on the basis of the sequential inactivation of myofibrillar actomyosin ATPase during acid preincubation. When this method is used in combination with the standard alkaline preincubation at least 5 types of fibers can be identified. Of these, 2 are type I fibers with those of the slow twitch soleus muscle being different from those that exist in mixed muscles. The 3 subtypes of type II fibers exist independent of their metabolic properties. The need for careful standardization of histochemical methods for the visualization of myofibrillar actomyosin ATPase and the implication of the existence of different fiber types in apparently homogeneous muscle for the preparation of antibodies used for immunocytochemical methods of fiber identification are discussed.     

Effect of Sustained Maternal Hyperglycaemia on the Fetus in Normal and Diabetic Pregnancies

The effect of prolonged maternal hyperglycaemia on fetal plasma glucose and insulin concentrations was investigated in eight normal and nine diabetic patients. It was found that under fasting conditions the fetal glucose concentration in gestational diabetic pregnancies tended to be lower than in normal pregnancies. Insulin measurements suggested that this may be due to fetal hyperinsulinism in the diabetic group. During glucose infusion, regardless of the degree of maternal hyperglycaemia, the fetal glucose concentration was limited in 12 out of 13 cases to less than 200 mg/100 ml, with only small differences between normal and diabetic pregnancies. It is proposed that the placenta prevents unlimited transport of glucose to the fetus; yet in diabetic pregnancies a sequence of increased maternal-fetal glucose transport, fetal hyperinsulinism, and fetal hypoglycaemia may contribute to the observed perinatal mortality.     

Cloning of the riboB locus of Aspergillus nidulans

We have complemented the riboB2 mutation of Aspergillus nidulans by transformation with a plasmid library of wild-type (wt) sequences. We have isolated, by marker rescue from a riboB+ transformant, a plasmid that complements riboB2 efficiently. From this plasmid we have subcloned an A. nidulans sequence that complements riboB2 efficiently and that integrates by homologous recombination at a site closely linked to the riboB locus. We conclude that this sequence contains the wt riboB+ allele.     

Settlement and growth of Antipathes pennacea on a shipwreck

A large population of the black coral Antipathes pennacea (Pallas) was studied underwater on a 37 year old shipwreck in Jamaican waters. The occurrence of A. pennacea at depths of 30–32 m supports previous observations that the minimum depth for black corals is reduced in turbid waters. Specimens of A. pennacea were found only on the underside of overhangs and 96 were measured. This pattern of occurrence suggests that the angle of inclination of the substrate is assesed prior to larval settlement. A. pennacea morphology was density dependent; isolated individuals grew three dimentionally in the form of a bush, the major stem being circular in cross section. Crowded individuals however, were tall with thin, oval or hourglass shaped stems and had a vertically orientated fan shape. The largest crowded individuals averaged growth rates of 57 mm height/year while the largest isolated individuals averaged 0.92 mm stem diameter/year.