Further purification and partial characterization of the rat lung cytoplasmic factors modulating adenylate cyclase activity in plasma membrane.

The adult rat lung cytoplasm contains some factors which markedly stimulate adenylate cyclase activity in plasma membranes (Nijjar, M.S. Biochim. Biophys. Acta 584:43-50, 1979). Adenylate cyclase activator (ACA) was purified from rat lungs by DEAE-cellulose chromatography, preparative isoelectric focusing and by repeated high-performance liquid chromatography on a Sepharogel TSK 2000SW column. The final preparation showed about 200 fold purification in ACA activity over the original lung supernatant, and appeared to be homogeneous on the basis of its migration into a single band on SDS-polyacrylamide gel electrophoresis, and co-elution of ACA activity with protein from a gel exclusion column. ACA is an acidic (pI 4.8 +/- 0.1), heat labile, monomeric protein of 40,000 +/- 2,000 dalton molecular weight, and does not resemble calmodulin.

The effect of maternal diabetes on the synthesis and secretion of phosphatidylcholine in fetal and maternal rat lungs in vitro.

Incorporation of (methyl-14C)choline into phosphatidylcholine and the release of prelabelled phosphatidylcholine was investigated in vitro using lung slices from pregnant rats and their offspring near term. Tissue from normal, diabetic and insulin-treated diabetic pregnant rats and their offspring was utilized to assess the effects of maternal diabetes on fetal lung maturation. The results show that the synthesis of phosphatidylcholine in fetal/newborn lungs through the cytidine 5'-diphosphocholine pathway was not affected by maternal diabetes. However, secretion of phosphatidylcholine from the lungs of fetuses of diabetic mothers was very much suppressed one day after parturition. Insulin treatment of the diabetic pregnant rats restored secretion of phosphatidylcholine from the fetal/newborn lungs to control values. These results suggest that an impaired secretion of phosphatidylcholine from the lungs of fetuses of diabetic mothers may be partly responsible for the higher incidence of respiratory distress syndrome among children of diabetic mothers. The results also revealed some correlation between the secretion of phosphatidylcholine from maternal lungs, maternal serum phospholipids and synthesis of phosphatidylcholine by fetal lungs during late gestation, suggesting a possible relationship between maternal phospholipid metabolism and fetal lung maturation.

Combining ability analysis of beta-Carotene, total carotenoids and other grain characteristics in pearl millet.

Combining ability studies with respect to grain quality characteristics viz., beta-Carotene, total carotenoids, protein content, 250-grain weight, grain hardness and grain yield were carried out from a 13x13 diallel cross set in pearl millet [Pennisetum typhoides (Burm S&H)].The parents versus hybrids comparison indicated significant heterosis for all the traits under study. In general the hybrids having higher grain yield had bold hard grains with more carotene but low protein content, although a few hybrids combined high yield with an average protein percentage. The relative proportions of the general and specific combining ability variances indicated predominance of non-additive genetic variance with respect to all the traits. The per se performance of parents provided a fairly good indication of their combining ability in most cases. Parents possessing desirable grain quality characteristics were identified. Breeding implications are discussed.