The effect of food deprivation on enzyme activity in developing brain

Brain and body weights, contents of DNA and protein and activities of 1,6-diphosphofructoaldolase (aldolase, EC 4.1.2.13), creatine phosphokinase (CPK, EC 2.7.3.2), and isocitric dehydrogenase (ICD, EC 1.1.1.42) in brain (minus cerebellum and brain stem) were studied in control and food-deprived rats at 7, 14 and 21 days of postnatal age. Activities of all three enzymes per brain were less in the food-deprived animals. In both groups of rats the ratios of aldolase/DNA and CPK/DNA increased with maturation, indicating that increasing activity per brain during maturation was the result of both increased activity per cell and increased numbers of cells. The ratio of ICD/DNA decreased with maturation but was essentially the same in both the food-deprived and control groups. Increase of ICD activity per brain with maturation was attributable to increased numbers of cells. Food deprivation in immature animals resulted in lowered activities per brain for aldolase, CPK and ICD because of diminished cell multiplication.     

Phosphorylating-dephosphorylating enzymes of avian oviductal secretions

Avian oviductal fluids contain phosphorylating-dephosphorylating enzymes that might function in sperm-oocyte interactions. Phosphorprotein phosphatase and protein kinase have been purified 20-fold and 40-fold, respectively. The latter easily aggregates and is highly labile. Other properties are comparable to those of holoenzymes.     

Development of ovaries in bovine fetuses

The growth of ovaries, development of germ cells, formation of sex cords, folliculogenesis and dependence of these processes on the gonad morphogenesis stages were studied on 68 embryos and foetuses at the age of 1.5 to 9 months. Sex differentiation of ovaries was shown to take place in 1.5 month old embryo. The cords of connective tissue's cortical stroma appear also in 1.5 month old embryo, they develop in the dorsoventral direction and reach the gonad's covering epithelium in 6 month old foetuses. The formation of the medulla rudiment starts in 1.5 month old embryo when the gonad is separated from mesonephros and connected with it via the ovary gate. In 4 month old foetuses the ovary net transforms into a stellate structure. Important morphogenetic processes, such as the development of the ovary somatic elements, entry of the oocytes into meiotic prophase, formation of the sex cords and folliculogenesis, develop in the dorsoventral direction Germ cells in 9 month old foetuses are enclosed into primordial or, growing follicles.     

Thermal melting and circular dichroism of DNA complexes with (Lys-Ala-Ala)10 and (Lys-Ala-Ala)n: effect of polypeptide chain length

DNA complexes with polypeptides (Lys-Ala-Ala)₁)] and (Lys-Ala-Ala)₃₄ have been studied using the methods of thermal melting and circular dichroism. Derivative melting curves of (Lys-Ala-Ala)₁₀ DNA differed substantially from those of (Lys-Ala-Ala)₃₄ prepared either by salt gradient dialysis or by direct mixing. Melting curves of the former complex were unimodal or bimodal with T_m increasing continuously withn input lysin-to-DNA phosphate ratio (r); those of the latter complex consisted of three separate transitions with T_m values almost independent of r. Complete reversibility of binding in the (Lys-Ala-Ala)₁₀-DNA system but a slow redistribution of (Lys-Ala-Ala)₃₄ on DNA at low temperature were found in the redistribution experiments Much faster redistribution from denatured to native DNA occurs at the temperature of melting, contributing to the unusual trimodal melting pattern. Circular dichroism curves are very similar for both complexes and indicate little change of DNA conformation upon polypeptide binding.