A new protein factor functional in the ferredoxin-independent light activation of chloroplast fructose 1,6-bisphosphatase

A protein purified from chloroplasts (the “new protein factor”) activated Fru-P₂ase in a photochemical reaction that depended only on chloroplast membranes. The results suggest that chloroplasts utilize the newly found mechanism for the photoregulation of Fru-P₂ase in addition to the recently described ferredoxin/thioredoxin system.     

Steroid sulphatase levels in XX males,including observations on two affected cousins

Summary Quantitative assays of steroid sulphatase in XX males have shown that some individuals have two functional loci, and others only one. Two affected cousins, who cannot share the same X-chromosome, nevertheless have male levels of steroid sulphatase, suggesting functional abnormality of the X chromosome.The hypothesis is advanced that these and other unusual features of X-chromosome function in some XX males, could be explained if such cases were due to an autosomal mutation, exercising its effect by causing abnormal inactivation of a subterminal area of Xp which normally escapes the inactivation process.     

Restriction endonuclease analysis of the transducing bacteriophage lambda rif d18

The rif d18 bacteriophage carries essential parts of the E. coli genome which can not be mapped by conventional methods. The phage DNA was analysed with four restriction endonucleases (endo R. BamHI, Sall, HpaI and EcoRI) and a physical map was constructed.     

Cytodiagnosis of gastric ulcer penetration of the liver by examination of endoscopic brushings

The penetration of a gastric peptic ulcer into the liver was initially diagnosed by the cytologic examination of endoscopic brushings and later confirmed by an endoscopic biopsy of the stomach. One of the smears of the gastric brushing contained sparse groups of liver cells with mild atypia. The endoscopic biopsy specimen included liver parenchyma with signs of peptic hepatitis. The differential diagnostic considerations for a gastric brushing containing hepatoid cells are discussed.     

Light modulation and in vitro effects of adenine nucleotides on leaf nitrate reductase activity in cucumber (Cucumis sativus)

Nitrate reductase (NR, EC 1.6.6.1) activity in attached cucumber ( Cucumis sativus L. cv. Ashley) leaves changed rapidly and reversibly during light/dark transitions, especially when assayed in the presence of free Mg²⁺. Light decreased and darkness increased the sensitivity of the enzyme to inhibition by Mg²⁺. The NR activation state, i.e. activity in the presence of Mg²⁺ relative to activity in the absence of Mg²⁺, increased with light intensity up to 400 μmol m⁻² s⁻¹ PAR (photosynthetically active radiation). When a desalted crude extract from illuminated leaves was preincubated with ATP, NR was gradually inactivated. Inactivation was only observed when activity was assayed in the presence of Mg²⁺. The ATP-inactivated NR remained inactive after removing the excess of ATP by gel filtration and it did not occur in partially purified NR preparations. NR extracted from darkened attached leaves was markedly activated when preincubated with 5'-AMP. These results support the view that inactivation/activation of cucumber-leaf NR in response to light/dark signals most likely involves phosphorylation/dephosphorylation of the enzyme catalysed by endogenous proteins. A substantial activation of NR by preincubation with 5'-AMP was also observed when activity was assayed in the absence of Mg²⁺, thus indicating that 5'-AMP can directly activate NR. Irradiation of an extract from darkened leaves containing FAD promoted a partial activation of NR. This effect was observed both in the +Mg²⁺ and in the −Mg²⁺ assay, indicating that activation was caused by photoexcited flavin and did not involve dephosphorylation of the enzyme.     

Adenine nucleotide content and energy charge of Bacillus megaterium during batch growth in low-phosphate medium

Abstract The effect of a low phosphate concentration on intracellular adenine nucleotides, oxygen consumption and poly-β-hydroxybutyric acid synthesis, was investigated with batch cultures of Bacillus megaterium . At low phosphate concentrations the cells contained much larger amounts of poly-β-hydroxybutyric acid, but displayed lower adenylate energy charge and oxygen uptake than did control cells. The ratio of ATP to ADP was much greater in the control cells. The levels of ATP and AMP were lower in low-phosphate cells.     

Adenine nucleotide content and energy charge in dry cells and cysts of Azotobacter vinelandii

Abstract The levels of intracellular adenine nucleotides, energy charge, oxygen consumption and poly-β-hydroxybutyric acid stored, have been investigated in dry vegetative cells and cysts of Azotobacter vinelandii . The data show that under desiccation conditions the cysts retain viability at energy charge values of 0.20 and an ATP/ADP ratio of 0.24, whereas under the same desiccation conditions, vegetative cells die at energy charge values <0.5 and an ATP/ADP ratio of <0.6.     

Developmental pattern of Δ5 3β-hydroxysteroid dehydrogenase activity in isolated rat Leydig cells

A direct method for determination of Δ⁵ 3β-hydroxysteroid dehydrogenase (3β-HSD) activity was employed in isolated Leydig cells (LC) derived from rats on fetal day 19 (F₁₉) and postnatal (N) days 1,12,24, 34 and 45 and adults. The activity of 3β-HSD in the adult LC was 1.15 ± 0.02 (μmole/μg DNA/hr, mean ± SEM, n = 73). Activities in the other groups, expressed as a percentage of the respective adult control, were: F₁₉-38%; N₁-39%; N₁₂-8%; N₂₄-89%; N₃₄-166%; and N₄₅-118%. A good correlation was found between histochemical staining for 3β-HSD and the quantitive method employed. Using (³H)-DHA as a substrate, LC isolated from F₁₉, n₁ and N₁₂ produced testosterone in appreciable amounts (41%, 55% and 20% of the toal products respectively) whereas at advanced stages of development (N₂₄ to adulthood) the major product was androstenedione (93 ± 1%). These findings may be explained by the observed decrease in 17β-hydroxysteroid dehydrogenase (17β-HSD) activity, due to an insufficient supply of NADPH, in the older vs. earlier stages of development. This study indicates the presence of steroidogenic enzymatic activity in LC throughout development in the rat. It also provides a relatively simple in vitro model for studies of testicular regulation during development.