Kinetics of electron transfer between the primary and the secondary electron acceptor in reaction centers from Rhodopseudomonas sphaeroides.

Photoreduction of the two ubiquinone molecules, UQ1 and UQ2, bound to purified reaction center from Rhodopseudomonas sphaeroides induces different absorption band shifts of bacteriochlorophyll and bacteriopheophytin molecules depending on which ubiquinone is photoreduced. This allows us to study electron transfer between UQ1 and UQ2 directly by absorption spectrometry. The results support a model in which electrons are transferred one by one from UQ1 to UQ2 with a half-time 200 micro seconds, and two by two from fully reduced UQ2 to the secondary acceptor pool.     

Orientation of the hemes of high potential cytochromes relative to photosynthetic membranes, as shown by the linear dichroism of oriented preparations

The orientations of high potential cytochromes with respect to photosynthetic membranes was investigated in spinach chloroplasts and in Rhodopseudomonas viridis. The general approach consists in detection with polarized light of photoinduced absorbance changes related to the oxidation of the cytochromes. The orientation of cytochrome c-558 was measured at room temperature in chromatophores and whole cells of Rps. viridis, oriented on glass slides and in a magnetic field, respectively. The orientation of cytochrome b-559 of green plants was detected at 77 K in magnetically oriented chloroplasts. In both cases the dichroic ratio for the band shows that the heme plane makes an angle greater than 35°C with the membrane plane. Moreover, the dichroic ratio is not constant throughout the and β bands, for both cytochrome c-558 and b-559. Linear dichroism spectra of oriented pure horse heart cytochrome c and cytochrome c₂ of Rhodopseudomonas sphaeroides in stretched polyvinyl alcohol films show that the variations of the dichroic ratio in the and β bands can be explained by the occurrence of x- and y-polarized transitions absorbing at slightly different wavelengths.     

The annual lipid cycle and feeding behavior of Alaskan redpolls

Summary Total lipids were extracted from 161 redpolls (Acanthis spp.) collected each month of the year from October 1962 to September 1963, in interior Alaska. A lipid index (Weight of ether extract x100/live body weight) was calculated for each sample. Lipids were also extracted from sections of pectoral muscle, livers and hearts representing each month.Body weight and lipid index were significantly positively correlated being highest in January and lowest in September. Total lipid content was significantly inversely correlated with air temperature; the high autumn and spring pre-migratory lipid peaks of migratory species were only weakly expressed in the redpolls. Liver lipid showed a significant annual variation being highest in December and lowest in August, while lipid from heart and pectoral muscle did not vary seasonally.Five birds were held in captivity during spring and summer at a constant temperature of 22°C. Food consumption was 5.1 g/day or 22.4 kcal. The caloric value of the most extensively utilized natural food, birch seed (Betula papyrifera), was determined (5.4–5.5 kcal/g dry wt). When esophageal diverticulae are full (2.0 g wet wt) of birch seeds, the resulting energy yield may sustain an individual for only a fraction of a 24 h winter day in contrast to other arctic herbivores (e.g. ptarmigan, Lagopus sp.) in which a full crop may suffice for the full 24 h period.     

The role of glucagon in the regulation of blood glucose: Model studies

Mathematical models afford a procedure of unifying concepts and hypotheses by expressing quantitative relationships between observables. The model presented indicates the roles of both insulin and glucagon as regulators of blood glucose, albeit in different ranges of the blood glucose concentrations. Insulin secretion is induced during hyperglycemia, while glucagon secretion results during hypoglycemia. These are demonstrated by simulations of a mathematical model conformed to data from the oral glucose tolerance test and the insulin infusion test in normal control subjects and stable and unstable diabetic patients. The model studies suggest the parameters could prove of value in quantifying the diabetic condition by indicating the degree of instability. Presented at the Society for Mathematical Biology Meeting, University of Pennsylvania, Philadelphia, August 19–21, 1976.     

Bile acids and bile alcohols in a child with hepatic 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase deficiency: effects of chenodeoxycholic acid treatment

Duodenal bile, urine, plasma, and feces from a child with hepatic 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase deficiency were analyzed by fast atom bombardment mass spectrometry and gas chromatography-mass spectrometry to investigate the formation and excretion of abnormal bile acids and bile alcohols. The biliary bile salts consisted of glycocholic acid (25%) and of sulfated and glycine conjugated di- and trihydroxycholenoic acids (55%), two C27 bile acids, and eleven sulfated bile alcohols (mainly tetrols, 20%), all having 3 beta,7 alpha-dihydroxy-delta 5 or 3 beta,7 alpha,12 alpha-trihydroxy-delta 5 ring structures. In plasma, sulfated cholenoic acids constituted 65% and unconjugated 3 beta,7 alpha-dihydroxy-5-cholestenoic acid 25% of the total level, 71 micrograms/ml. The urinary excretion of the former was 30.4 mg/day and that of unsaturated bile alcohol sulfates, mainly pentols, 7 mg/day. The predominant bile acid in feces was an unconjugated epimer of 3 beta,7 alpha,12 alpha-trihydroxy-5-cholenoic acid, and small amounts of cholic acid were present. The minimum total excretion was 11.3 mg/day. Treatment with chenodeoxycholic acid resulted in marked clinical improvement and normalized liver function tests. Further studies are needed to define the mechanism of action. Plasma bile acids decreased to 1.6 micrograms/ml and urinary excretion to 3.4 mg/day. Chenodeoxycholic and ursodeoxycholic acids became predominant in all samples. The fecal excretion of unsaturated cholenoic acid sulfates increased to 40 mg/day compared to 89 mg/day of saturated bile acids. The results provide further support for a defective hepatic 3 beta-hydroxy-delta 5-C27-steroid dehydrogenase deficiency, and indicate that the 3 beta-hydroxy-delta 5 bile acids are formed via 7 alpha-hydroxycholesterol. The formation of glycocholic acid may be due to an incomplete enzyme defect or to transformation of the 3 beta-hydroxy-delta 5 structure by bacterial and hepatic enzymes during an enterohepatic circulation.     

Reproduction and feeding ethology of a tropical,intertidal sand-dwelling anemone (Actinoporus elongatus,Carlgren, 1900)

Actinoporus elongatus is a widely distributed, tropical, intertidal anemone from the Indo-Pacific and Caribbean regions. Its recorded occurrences are disjunct and its feeding and reproductive ecology have not previously been described in detail. A population of this sand-dwelling species was studied for one year at Shelly Bay, Queensland, Australia. Individuals were found to be randomly distributed within the study site at a density of 42 anemones per hectare. No immigration, juvenile recruitment or mortality was observed. Histological analysis indicated a protracted period of gamete maturity during the summer months, and that the sex ratio was 1:1. A. elongatus is an opportunistic feeder with two distinct feeding methods — actinopharyngeal eversion and a newly described trapdoor response. Ciliary currents on the tentacular crown and oral disk were used mainly for cleaning and sand removal.Department of Zoology, James Cook University of North QueenslandDepartment of Marine Biology, James Cook University of North QueenslandDepartment of Marine Biology, James Cook University of North Queensland     

EFFECTS OF ICE ON ASCOPHYLLUM NODOSUM WITHIN THE GREAT BAY ESTUARY SYSTEM OF NEW HAMPSHIRE-MAINE12

The, effects of ice on Ascophyllum nodosum (L.) Le Jolis within the Great Bay Estuary System of New Hampshire-Maine, U.S.A. were assessed during the winter of 1980–81. Approximately 50% of the plants late fall standing crop, or an estimated 136 tonnes dry weight, was removed by ice-rafting. Pieces of Ascophyllum removed averaged 22 cm in length, 15 g in fresh weight and generally represented 2–3 years of growth. Although the winter of 1980–81 wax somewhat extreme, a similar pruning process probably occurs each year contributing to the characteristic bushy habit of attached inner estuarine plants. Ascophyllum fragments rafted in ice and deposited into salt marshes are suggested as a major source of the, ecad scorpioides (Hornemann) Hauck.     

Controlling the exotic diseases: 2. Nursing management.

Advance planning can facilitate the care of a patient with an exotic disease who is admitted to a hospital that lacks facilities for high-security isolation. The Department of National Health and Welfare contingency plan for dealing with such patients lacks specific information in a number of areas of medical care, as described in this paper. Consideration must be given to the number of personnel trained and readied for employment, the criteria for selection and special preparation. The protective clothing generally used for hospital isolation procedures is inadequate. Several types of special clothing, including a respirator, are available for total protection of personnel; the clothing may be uncomfortable when worn for long periods, and does restrict movement, vision and communication. All persons entering the isolation suite must change into fully protective clothing, and double layers of clothing are required for direct patient care. All personnel must shower and change before leaving the isolation suite. Suitable facilities for dressing and showering, together with entry and exit routines, must be considered. Hand washing, daily cleaning procedures and disposal of liquid and solid wastes all require special procedures. The social and psychologic problems of patients and their families must also be considered. Preplanning is required to decrease the risks involved in monitoring vital signs and implementing emergency procedures requiring contact with the patient''s blood.     

Solubilization of rat heart sarcolemma 5′-nucleotidase by phosphatidylinositol-specific phospholipase C

The influence of a phosphatidylinositol-specific phospholipase C treatment on rat heart sarcolemmal 5′-nucleotidase was investigated. Upon complete hydrolysis of all phosphatidylinositol in the sarcolemma, 75% of 5′-nucleotidase activity was found in the solubilized form. The insolubilized enzyme after this treatment has the same K_m for AMP as the untreated, sarcolemmal-bound enzyme (0.04 mM), whereas the solubilized enzyme has a 40-fold increase in K_m for AMP (0.16 mM). Other sarcolemmal-bound enzymes were not affected by the same treatment. Hence, the specific involvement of phosphatidylinositol in the binding of 5′-nucleotidase to the sarcolemma of the rat heart is clearly demonstrated.