TEMPERATURE CHARACTERISTICS FOR METABOLISM OF CHLORELLA : I. THE RATE OF O2 UTILIZATION OF CHLORELLA PYRENOIDOSA WITH ADDED DEXTROSE

The temperature characteristic for the rate of O₂ consumption by Chlorella pyrenoidosa suspended in Knop solution containing 1 per cent glucose was studied between 1° and 27°C. with the Warburg technic. The value of µ was found to be about 19,000 ±1,000 cal. There is some indication of a critical temperature at 20°C., with shift to a lower µ above this temperature. The effect of sudden changes in temperature on the rate of respiration and the variation of the latter with time at constant temperatures are discussed. It is concluded that the "normal" respiration (in absence of external glucose) does not appear in the determination of this temperature characteristic.     

TEMPERATURE CHARACTERISTICS FOR THE METABOLISM OF CHLORELLA : III. THE CATALYTIC DECOMPOSITION OF HYDROGEN PEROXIDE BY CHLORELLA PYRENOIDOSA

The decomposition of hydrogen peroxide by intact Chlorella cells follows a first order course at very low temperatures, but at higher temperatures gives falling first order constants. Between 0.6° and 20°C. the value of µ is 10,500 calories.     

THE EFFECT ON GABA METABOLISM IN BRAIN OF ISONICOTINIC ACID HYDRAZIDE AND PYRIDOXINE AS A FUNCTION OF TIME AFTER ADMINISTRATION

—The effect of intramuscularly administered INH on brain levels of GABA in chicks was dependent on the amount injected. A subconvulsant dose of INH (1·1 mmol/kg) produced a slow steady decline in the level of GABA, whereas a convulsant dose (2·19 mmol/kg) brought about a sequential fall and rise in GABA level. This sequence of events reflected changes in the relative activities of GAD and GABA-T brought about by the hydrazide. The administration of pyridoxine together with the INH (2·19 mmol/kg) prevented the onset of seizures and lessened the effect of the INH on GABA levels and GAD activity but not on GABA-T activity. The possibility that a deranged GABA metabolism is responsible for hydrazide-induced seizures is discussed.     

温度、盐度和pH对小球藻生长率的联合效应

采用中心复合设计（CCD）研究了温度（1634℃）、盐度（1545）和pH（6.09.0）对小球藻（Chlorella sp. CHX-1）生长的联合效应。结果表明,温度、盐度与pH的一次、二次效应都对小球藻比生长速率有极显著影响（P0.01）;温度与盐度间、温度与pH间的互作效应对小球藻比生长速率影响显著（P0.05）,而盐度与pH间的互作效应影响不显著（P0.05）;三因子影响度大小依次为:温度pH盐度。采用响应曲面法建立了温度、盐度和pH对小球藻比生长速率影响的模型方程,该模型的决定系数0.9759,矫正决定系数0.9542,说明模型的拟合度极高;模型的预测决定系数0.8367,表明可用于预测小球藻比生长速率的变化。通过模型优化和验证试验,得出在温度、盐度和pH组合为26.7℃/25.5/7.3时,小球藻比生长速率达到最大值0.69,满意度为0.999。本试验结果可为小球藻生产提供理论指导。       

鲇鱼的静止代谢率及其与体重,温度和性别的关系

采用连续流水式呼吸仪测定了１２７尾鲇鱼（体重２２．６－４５２．４ｇ）的静止代谢率。在１０,１５,２０,２５和３０℃水温下,鲇鱼平均特定体重代谢率分别为２２．９９,５８．５５,７９．２０,１０９．２９和１２３．８９ｍｇＯ２／ｋｇ／ｈ。体重（Ｗ）与静止代谢率（Ｍｓ）回归关系（Ｍｓ＝ａＷ＾ｂ）的体重指数ｂ随温度上升而下降,温度（Ｔ）与特定体重代谢率（Ｍ＇）回归关系（Ｍ＇＝ＡＴ＾Ｂ）的温度指数Ｂ随体重增加     

SYNCHRONOUS CULTURE OF CHLORELLA: I. KINETIC ANALYSIS OF THE LIFE CYCLE OF CHLORELLA ELLIPSOIDEA AS AFFECTED BY CHANGES OF TEMPERATURE AND LIGHT INTENSITY

1. Using the technique of synchronous culture, investigationsweremade of the effects of temperature and light-intensityon cellularlife cycle of Chlorella ellipsoidea. Some improvementsin theculture technique for obtaining a good synchrony of algalgrowthwere described.
2. By following the changes of averagecell volume and cell numberoccurring during culturing, therates of the following processesof life cycle were determined:(i) "growth" (or the increasein cell mass) occurring from thestage of smaller cells (D_a)to the stage of ripened cell (L₃),(ii) "ripening" (or processofformation of "nuclear substances"as estimated from the averagenumber of daughter cells formedfrom single mother cell), and(iii) " maturing and division" which leads to the full maturationof mother cells (L-cells)and their division into separate daughtercells (D-cells).
3. "Growth"and "ripening" were found to be dependent in light,"maturingand division" light-independent. The time requiredfor "growth"and "ripening" (C) is dependent on temperaturebut independentof light intensity, the onset of "maturing anddivision" occurringat the same time (D) of culturing undervaried light intensities.The average cell volume at this stage(L₃),however, was foundto be markedly modified by light intensity;larger with highertemperatures (see Fig. 4).
4. Changes in incubation temperature(under the condition of saturatinglight intensities) were foundto affect the life cycle in thefollowing way: (i) The timeof onset of "maturing and division"(D), varies markedly withculturing temperature; earlier athigher temperatures, (ii)The average cell volume at this stagealso depends on temperature; smaller at higher temperatures.
5. The average number of daughtercells (n) emerging from singlemother cells, was found to beuninfluenced by culturing temperature;(4.0–4.1 underthe conditions of the present study). Itwas found that thedivision number n is remarkably varied bychanging the lightintensity in the "growth" and "ripening"phases; 2.0 at 1 kilolux,3.7 at 5 kilolux, 4.2 at saturatinglight intensities (10 and25 kilolux). This finding was explainedby assuming a light-dependentformation of "nuclear substances"during the "growth" and "ripening"phases, the quantity of thesubstances in the cell at L₃ stagedeterminig the division number.
6. The experimental data wereanalyzed reaction kinetically, therate constants and othercharacteristics of the reactions constitutingthe processesof life cycle were determined, and values forthe apparent activationenergy for each reaction were computed.The reactions were discussedwith special reference to theirrelationship with photosyntheticprocess was discussed.

(Received November 7, 1959; )     

用胆固醇代谢的房室模型速率系数来分析动脉粥样硬化程度

理论上认为胆固醇逆向转运的速率与动脉粥样硬化程序呈负相关。但目前尚无完善的测试血浆脂蛋白－胆固醇体内代谢的方法。我们运用同位素＾３Ｈ－胆固醇示踪方法,建立房室模型,选取健康兔与ＡＳ兔对照,研究血浆脂蛋白转运胆固醇能力的差异,并结合ＡＳ兔主动脉斑块程度对比,结果验证了上述理论,此法如改用短半衰期同位素或稳定性同位素标记的胆固醇,就可用于人体,这可为临床判断ＡＳ程度提供一种无创性的新方法。     

PHYSIOLOGICAL ONTOGENY : A. CHICKEN EMBRYOS. XII. THE METABOLISM AS A FUNCTION OF AGE.

1. The previous findings that the rate of metabolism per gm. of body weight decreased with age, and that during the incubation period catabolism was mostly at the expense of fat, have been confirmed. 2. These determinations of the rate of oxygen uptake have afforded more precise values for the catabolic rate and thus permit estimations of the changes with age in the rate of absorption.     

RATES OF PHOTOSYNTHESIS AND RESPIRATION OF THE MOSS BRYUM SANDBERGII AS INFLUENCED BY LIGHT INTENSITY AND TEMPERATURE

Using differential respirometry and air enriched to 3% CO₂ (v/v), the rates of photosynthesis and dark respiration of the moss Bryum sandbergii were measured as influenced by temperature and light intensity. The optimal temperature for net (apparent) photosynthesis was between 24 to 30 C; however, the photosynthesis/respiration ratio was about 11 to 27 between 4 to 24 C and dropped to lower values at 34 C., which indicates a wide temperature tolerance for this moss in short-term experiments. The maximum temperature for photosynthesis was about 41 C and the minimum was below –5 C. At 20 C light saturation was approached at 6.2 mw cm^–2 (ca. 700 ft-c) but not completely reached at 12 mw cm^-2; the light compensation point was estimated to be 0.4 mw cm^-2 (ca. 40 ft-c). At 4 C light saturation and the compensation point were at lower levels and apparently solarization occurred at 12 mw cm^-2. Light intensity had little or no apparent effect on dark respiration. However, respiration increased with temperature over various ranges extending from –5 to 39 C with temperature quotients of about 2.5 to 1.2. The significance of these characteristics is discussed with respect to the ecological relationships of the species.     

ON THE RESPIRATORY QUOTIENT OF LUPINUS ALBUS AS A FUNCTION OF TEMPERATURE

The temperature characteristics for the oxygen consumption and CO₂-production of the germinating seeds of Lupinus albus were previously found to be different. It was predicted qualitatively that the respiratory quotient of the seed should be a function of temperature. A quantitative treatment is presented here, relating the change of the respiratory quotient with temperature and the temperature characteristics. Experimental results agree satisfactorily with the calculated value.     

BIOTIN LIBERATION BY THE LICHEN ALGA COCCOMYXA SP. AND BY CHLORELLA PYRENOIDOSA

The unicellular green alga Coccomyxa, a component of the lichenPeltigera aphthosa, liberated about 7.2mµg biotin permg dry weight of cells into the culture medium during a growthperiod of 15–20 days. The corresponding figure for thefree-living alga Chlorella pyrenoidosa was 0.45mµg ofbiotin. Chromatographic analysis indicated that this was freebiotin and not a bound form of the vitamin. The biotin concentrationof rinsed Coccomyxa cells was 1.88mµg per mg dry weightof cells, of which less than 0.01mµg was extractable byhot water. Cells of Chlorella contained 0.16mµg of biotinper mg dry weight, of which 0.11mµg was extractable byhot water. The biotin content of Coccomyxa, which was about12 times that of Chlorella, is thus almost entirely in the boundform. The importance of biotin in the symbiotic interactionsbetween the alga and the fungus in Peltigera is discussed. ¹Present address: University Department of Agriculture, Oxford,England. ²Present address: Institute of Marine Resources, Universityof California, La Jolla, California, U.S.A.     

METABOLISM OF TISSUE CULTURES : III. A METHOD FOR MEASURING THE PERMEABILITY OF TISSUE CELLS TO SOLUTES

By using radioactive isotopes in tissue cultures, the rate of permeation of substances into cells can be measured independently of concurrent metabolic reactions of these substances. Techniques of obtaining and analyzing data are described. Examples are given using radioactive potassium and phosphorus. Using cultures of chick embryo muscle, turnover time for cell potassium is 6 hours, and for cell inorganic phosphate is 7 hours in the examples cited. Permeability rates, based on estimates of the cell surface involved and expressed as millimoles per cm.² per hour, are of the order of magnitude of 10^–6 for potassium and of 10^–7 for phosphate.     

CULTURE CONDITIONS AND THE DEVELOPMENT OF THE PHOTOSYNTHETIC MECHANISM : II. AN APPARATUS FOR THE CONTINUOUS CULTURE OF CHLORELLA

1. An apparatus has been developed which maintains a constant density of population of Chlorella by automatic dilution of the growing culture with fresh medium. 2. Cells harvested from the apparatus in daily samples are highly uniform in rate of growth and rate of photosynthesis measured under arbitrarily chosen conditions.