Nitrogenase activity in extracts of heterocystous and non-heterocystous blue-green algae

Summary Cell-free extracts capable of acetylene reduction and cyanide reduction have been prepared from heterocystous (Anabaena cylindrica) and non-heterocystous (Plectonema boryanum 594) blue-green algae. Extracts from Anabaena were obtained from cultures grown in blulk under aerobic conditions, while the Plectonema cultures were grown in bulk on nitrate-nitrogen, then washed free from nitrate and sparged with A/CO₂ for 40 h after which time maximum nitrogenase activity was detected. The nitrogenases of both algae are similar and resemble in many respects nitrogenases from bacteria and legumes. Activity is located primarily in a 40,000xgx15 min supernatant fraction and the rate of C₂H₂ reduction observed is about 10 per cent of whole cell activity. ATP and a source of reducing power (Na₂S₂O₄) are required for efficient functioning of the enzyme. ATP-dependent hydrogen evolution occurs, the extracts are cold labile and highly sensitive to oxygen and the oxygen inhibition is irreversible.     

Lipolytic Esterases in Staphylococci

Staphylococci split a wide range of lipid substrates by production of an enzyme complex with two main components (i) a lipase acting optimally on fat-soluble glycerides, and (ii) an esterase acting optimally on water-soluble esters. The action is dependent upon carbon chain length, interfacial dispersion, solubility, and pH of substrate and end products. The esterase is less susceptible to organophosphorus inhibitors than mammalian esterases. There is no apparent correlation between lipolysis and markers of pathogenicity such as production of coagulase and toxin, but the possession of a flexible lipolytic mechanism might account for the persistence of staphylococci in the fatty secretions of mammalian skin.     

SPORADIC ACUTE GLOMERULONEPHRITIS IN ADULTS

Nineteen adults who had acute glomerulonephritis were reviewed with respect to the clinical course and long-term follow-up. The age range was from 17 to 55 years. Only one patient died during the acute episode. In 11 cases, onset occurred between November and January and 15 of the patients had a known respiratory tract infection three to 30 days before the onset. The most important symptoms noted were weight gain, edema, dyspnea, oliguria and red or smoky urine. The most prominent physical signs were elevated blood pressure, edema, abnormalities in the chest and fever of over 100° F. Fifteen patients showed roentgen evidence of pulmonary vascular congestion, pleural effusion, cardiomegaly, pneumonia or a combination of these abnormalities. All the patients had proteinuria and red blood cells in the urine, and half of them had red blood cell casts. Azotemia, when present, subsided in 9.4 days. The average diastolic pressure was 105 mm. of mercury and the mean fall was 26 mm. in 23.5 days. At six months, nine of the 13 patients still being observed continued to show proteinuria or microscopic hematuria (seven showed both). A late follow-up of ten patients showed one to have significant hypertension and one to have early functional impairment and inconstant proteinuria. In these cases the average blood pressure was 140/91 mm. as compared with 119/74 mm. at the time of discharge.Sporadic glomerulonephritis in adults presents essentially the same pattern as it does in children. Urinary abnormalities may persist for months or even years, and neither the present series nor those reported by others clearly reveal the ultimate prognosis.     

Rates of Dissolution of Tolbutamide Tablets

An investigation was made of the pharmaceutical properties and the in vitro dissolution rates of 18 commercially available brands of tolbutamide tablets, all of which met the limits set by the Food and Drug Regulations for tablets sold in Canada.A marked variation in dissolution rates was found, which bore no relation to the official disintegration time. These wide variations in dissolution rate point to a need for (a) a comprehensive study of the in vivo effects of different tolbutamide tablets, and (b) an official test that sets limits for the rate of dissolution of tolbutamide tablets, in addition to the one that places limits on disintegration time.     

Diffusive resistances at, and transpiration rates from leaves in situ within the vegetative canopy of a corn crop

At several heights and times of day within a crop of Zea mays, internal leaf diffusion resistance (r_i) and external boundary layer diffusion resistance (r_a) were evaluated by measuring the temperature of a transpiring and a non-transpiring leaf (simulated by covering both sides of a normal leaf with strips of poly-ethylene tape), and by measuring the immediate air temperature, humidity and windspeed.

Both r_a and r_i increased with depth into the crop. However, r_a generally was less than 10% of r_i.

Profiles of latent-heat flux density and source intensity of transpiration showed that transpiration corresponded roughly to foliage distribution (with an upward shift) and were not similar to the profile of radiation absorption.

The data were compared with heat budget data. The 2 approaches yielded quite similar height distributions of transpiration per unit leaf area and total transpiration resistance.

The total crop resistance to transpiration was computed as 0.027 min cm⁻¹. This compares to Monteith's values of 0.017 to 0.040 min cm⁻¹ for beans (Phaseolus vulgaris L.), and Linacre's values of 0.015 to 0.020 min cm⁻¹ for turf.