scholarly journals NITRATE REDUCTION AND ASSIMILATION IN CHLORELLA

1948 ◽  
Vol 32 (1) ◽  
pp. 93-102 ◽  
Author(s):  
Marian Cramer ◽  
Jack Myers
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Nitrate Reduction ◽  
Relative Rate ◽  
Chlorella Pyrenoidosa ◽  
Carbon Dioxide Production ◽  
Growth Conditions ◽  
Low Light ◽  
Carbon Dioxide Uptake ◽  
Elementary Analysis

1. Nitrate reduction and assimilation have been studied in Chlorella pyrenoidosa under growth conditions by observing effects on the CO2/O2 gas exchange quotient. 2. During assimilation of glucose in the dark, nitrate reduction is noted as an increase in the R.Q. to about 1.6 caused by an increased rate of carbon dioxide production. 3. During photosynthesis at low light intensity nitrate reduction is evidenced by a reduction in the CO2O2 quotient to about 0.7 caused by a decreased rate of carbon dioxide uptake. 4. Chlorella will assimilate nitrogen from either nitrate or ammonia. When both sources are supplied, only ammonia is utilized and no nitrate reduction occurs. It is inferred that under the usual conditions of growth nitrate is reduced only at a rate required for subsequent cellular syntheses. The effect of nitrate reduction on the CO2O2 quotient therefore provides a measure of the relative rate of nitrogen assimilation. 5. Over-all photosynthetic metabolism may be described from elementary analysis of the cells since excretory products are negligible. The gas exchange predicted in this way is in good agreement with the observed CO2/O2 quotients.

EFFECTS OF HERBICIDES ON CARBON DIOXIDE UPTAKE BY PINE SEEDLINGS

1967 ◽  
Vol 45 (7) ◽  
pp. 961-971 ◽  
Author(s):  
S. Sasaki ◽  
T. T. Kozlowski
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Soil Surface ◽  
Pinus Resinosa ◽  
Spray Application ◽  
Leaf Color ◽  
Carbon Dioxide Uptake ◽  
Chlorophyll Breakdown ◽  
Pine Seedlings ◽  
Steady Rate

Experiments were conducted on effects of herbicides applied to soil or sprayed on shoots on CO2 uptake of 3-year-old Pinus resinosa Ait. seedlings. When applied to the soil, atrazine, monuron, EPTC, and 2,4-D at 20 lb/ac (soil surface basis) or at 4000 p.p.m. variously decreased absorption of CO2. Monuron checked gas exchange most rapidly, with no CO2 uptake measurable after 10 days. Atrazine and 2,4-D inhibited absorption of CO2 at a steady rate. EPTC caused a delayed inhibition of CO2 uptake. DCPA, CDAA, CDEC, and NPA did not affect gas exchange significantly. Monuron applied as a spray depressed CO2 uptake somewhat faster than the soil-applied herbicide. Very rapid inhibition of CO2 uptake was observed after spray application of 2,4-D or EPTC. Atrazine affected gas exchange similarly when applied as a spray or incorporated in the soil. DCPA, applied as a spray, did not affect absorption of CO2 significantly. Possible reasons for differences in CO2 uptake after spray and soil-application of certain herbicides are discussed. Inert ingredients of EPTC applied as sprays at a concentration of 4000 p.p.m. greatly reduced CO2 absorption 3 days after treatment. However, the rapid early depression of gas exchange was followed by recovery, with no obvious deleterious effects on growth up to 3 months after treatment. Some herbicides checked CO2 absorption without chlorophyll breakdown whereas others did not. Monuron completely inhibited CO2 uptake long before any changes in leaf color were evident. In contrast, depression of CO2 absorption by atrazine and 2,4-D rather closely paralleled development of toxicity symptoms, especially chlorosis. These observations suggested that some herbicides such as monuron affected the photosynthetic mechanism more directly than others such as atrazine, 2,4-D, and EPTC.

Quantitative methanol-burning lung model for validating gas-exchange measurements over wide ranges of F I O 2

1998 ◽  
Vol 84 (6) ◽  
pp. 2177-2182 ◽  
Author(s):  
Saul Miodownik ◽  
Jose Melendez ◽  
Vittoria Arslan Carlon ◽  
Brian Burda
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Gas Exchange ◽  
Combustion Rate ◽  
Respiratory Quotient ◽  
Infusion Rate ◽  
Carbon Dioxide Production ◽  
Lung Model ◽  
Burner Device ◽  
Extended Range

The methanol-burning lung model has been used as a technique for generating a predictable ratio of carbon dioxide production (V˙co 2) to oxygen consumption (V˙o 2) or respiratory quotient (RQ). Although an accurate RQ can be generated, quantitatively predictable and adjustableV˙o 2 andV˙co 2 cannot be generated. We describe a new burner device in which the combustion rate of methanol is always equal to the infusion rate of fuel over an extended range of O2 concentrations. This permits the assembly of a methanol-burning lung model that is usable with O2 concentrations up to 100% and provides continuously adjustable and quantitativeV˙o 2 (69–1,525 ml/min) and V˙co 2 (46–1,016 ml/min) at a RQ of 0.667.

Responses to Humidity by Stomata of Nicotiana glauca L. And Corylus avellana L. Are Consistent With the Optimization of Carbon Dioxide Uptake With Respect to Water Loss

1980 ◽  
Vol 7 (3) ◽  
pp. 315 ◽  
Author(s):  
GD Farquhar ◽  
ED Schulze ◽  
M Kuppers
Keyword(s):  
Carbon Dioxide ◽  
Boundary Layer ◽  
Gas Exchange ◽  
Water Loss ◽  
Corylus Avellana ◽  
Carbon Gain ◽  
Nicotiana Glauca ◽  
Carbon Dioxide Uptake ◽  
Total Conductance ◽  
Corylus Avellana L

Intact leaves of N. glauca and C. avellana were exposed to a range of humidities and their gas exchange monitored. Rates of transpiration and assimilation of carbon dioxide, and their sensitivities to changes in total conductance (leaf and boundary layer) were determined. The ratio of these sensitivities, δE/δA, remained substantially constant over the range of humidities. The results represent the first experimental support for a recent hypothesis that stomata vary their apertures in such a manner as to keep δE/δA constant, which optimizes carbon gain with respect to water loss.

scholarly journals TEMPERATURE CHARACTERISTICS FOR THE METABOLISM OF CHLORELLA

1934 ◽  
Vol 18 (2) ◽  
pp. 193-207 ◽  
Author(s):  
C. S. French ◽  
H. I. Kohn ◽  
P. S. Tang
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Green Alga ◽  
Constant Temperature ◽  
Chlorella Pyrenoidosa ◽  
Carbon Dioxide Production ◽  
Constant Level ◽  
Temperature Characteristics ◽  
Green Alga Chlorella

The respiration of the green alga Chlorella pyrenoidosa, suspended in Knop's solution, has been studied in the dark as a function of time and of temperature. The rates of oxygen consumption and of carbon dioxide production (at constant temperature) decline for about 25 hours to a low, constant level. From an analysis of the curves it is suggested that two substances, A and B, are utilized, whose respiratory quotients are 1 and 0.65 respectively. The values of the temperature characteristics were found to be: for oxidation of A, 19,500 (0.6 to 11.5°C.) and 3,500 (11.5 to 28°C.); for oxidation of B, 5,600 (23.4 to 0.6°C.).

scholarly journals The Relative Efficiency of Gaseous Exchange Across the Lungs and Gills of an African Lungfish Protopterus Aethiopicus

1970 ◽  
Vol 52 (1) ◽  
pp. 1-15
Author(s):  
B. R. McMAHON
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Gas Exchange ◽  
Direct Measurement ◽  
Relative Efficiency ◽  
Lung Ventilation ◽  
Carbon Dioxide Production ◽  
Gaseous Exchange ◽  
Terrestrial Vertebrates ◽  
African Lungfish

1. The efficiency of gas exchange over the lung and gill surfaces of Protopterus has been investigated. 2. Animals confined in water or in air showed an increased respiratory frequency in the remaining medium, indicating that both routes were important in the total gas exchange. 3. Direct measurement of the oxygen and carbon dioxide tensions of pulmonary air and inspired and expired branchial water showed gas exchange ratios (R) of 0.2 for the lung and 5.0 for the gills approximately, demonstrating that more oxygen was consumed via the lungs and more carbon dioxide excreted via the gills. 4. Oxygen consumption and carbon dioxide production were measured directly in a respirometer in which respiratory air and water streams could be kept separate except during lung ventilation. At least 90% of the animals' oxygen consumption occurred in the lung, while 60 % of the carbon dioxide excreted passed via the aquatic route. 5. The results are discussed with reference to the animals' adaptation to its environment and with reference to the evolution of the terrestrial vertebrates.

The Exchange of Oxygen and Carbon Dioxide Across the Gills of Rainbow Trout

1967 ◽  
Vol 46 (2) ◽  
pp. 339-348 ◽  
Author(s):  
D. J. RANDALL ◽  
G. F. HOLETON ◽  
E. DON STEVENS
Keyword(s):  
Carbon Dioxide ◽  
Rainbow Trout ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Transfer Factor ◽  
Rate Ratio ◽  
High Capacity ◽  
Salmo Gairdneri ◽  
Moderate Exercise ◽  
Carbon Dioxide Uptake

1. The effectiveness of oxygen uptake by the blood of rainbow trout (Salmo gairdneri) approaches 100%, whereas that for the removal of oxygen from water was only 11-30%. 2. Most of the carbon dioxide is removed from the blood as it passes through the gills, but the effectiveness of carbon dioxide uptake by water is very low, because of the high capacity of water for carbon dioxide compared with oxygen. 3. Moderate exercise had little effect on the effectiveness of gas exchange across the gills. The increased oxygen uptake was facilitated by an increase in the transfer factor of the gills for oxygen. There were small increases in the capacity-rate ratio of blood to water at the gills during moderate exercise. 4. Hypoxia resulted in a marked decrease in the effectiveness of oxygen uptake by the blood, but had little effect on oxygen removal from the water. Gas exchange was facilitated during hypoxia by an increase in transfer factor of the gills, but hindered by an increasing capacity-rate ratio of blood to water at the gills. 5. Gas exchange in an aquatic environment was compared with that in an aerial environment.

scholarly journals The influence of temperature on the metabolic regulation and gas exchange of the Highveld scorpion, Opistophthalmus latimanus ( Koch ) ( Scorpionidae )

2012 ◽  
Vol 31 (1) ◽  
Author(s):  
Willie J. Van Aardt ◽  
Japie Mienie ◽  
J.M. Le Roux
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Gas Exchange ◽  
Oxygen Consumption Rate ◽  
Metabolic Regulation ◽  
Consumption Rate ◽  
Carbon Dioxide Production ◽  
Influence Of Temperature ◽  
Influence Of Temperature On ◽  
Carbon Dioxide Production Rate

Adult scorpions (2.4g – 4.5 kg) were collected near Potchefstroom (26° .55’10” – 27° 10” 5”). Oxygen consumption rate (MO2) and carbon dioxide production rate (MCO2) were measured together with the metabolism of injected radioactive glucose.

Alterations in ventilation and gas exchange during exercise-induced carbohydrate depletion

1979 ◽  
Vol 57 (6) ◽  
pp. 615-618 ◽  
Author(s):  
H. Green ◽  
M. Houston ◽  
J. Thomson ◽  
P. Reid
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Gas Exchange ◽  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Carbon Dioxide Production ◽  
Progressive Reduction ◽  
Energy Substrate ◽  
Carbohydrate Depletion ◽  
Exercise Induced

The relationships between ventilation [Formula: see text], oxygen consumption [Formula: see text], and carbon dioxide production [Formula: see text] during work were studied in four trained males during exercise-induced carbohydrate depletion. Repeated bouts of heavy treadmill exercise (6 min at 95% [Formula: see text]max) were performed once per hour for 24 h in order to promote a shift in energy substrate from carbohydrate to fat. Measurements of [Formula: see text] and [Formula: see text] recorded during each minute indicated that [Formula: see text] was unaffected by the number of runs, whereas [Formula: see text] showed a progressive reduction which amounted to 24% during the final run. A corresponding decline of 19% was observed in the respiratory exchange ratio. No significant change in [Formula: see text] occurred between any of the runs. It is concluded that during heavy, repeated, muscular exercise, reductions in [Formula: see text], strongly suggestive of an increased fat oxidation, are not accompanied by a corresponding change in ventilation.

scholarly journals Effects of Brief Anaerobic Exposures on Carbon Dioxide Production and Quality of Harvested Asparagus

1994 ◽  
Vol 119 (3) ◽  
pp. 551-555 ◽  
Author(s):  
Ana Victoria Torres-Penaranda ◽  
Mikal E. Saltveit
Keyword(s):  
Carbon Dioxide ◽  
Relative Rate ◽  
Carbon Dioxide Production ◽  
Anaerobic Treatment ◽  
Asparagus Officinalis ◽  
Visual Evaluation ◽  
Appearance Quality ◽  
Significant Difference ◽  
And Control

Freshly harvested asparagus (Asparagus officinalis L.) spears were exposed to an anaerobic N2 atmosphere for 0, 2, 4, or 6 hours at 2.5 or 20C and then returned to 2.5C. Carbon dioxide production was measured each day, starting 3 days before and ending 11 days after the treatment. Significant increases in CO2 production relative to 0-hour controls were found within 1 day of treatment at 20C and were directly proportional to the duration of the anaerobic exposure. At 2.5C, CO2 production relative to the 0-hour control was stimulated by the 2- and 4-hour treatments and depressed by the 6-hour treatment, with the relative rate of production inversely proportional to the duration of the anaerobic treatment. A decrease in CO2 production occurred 7 days after N2 treatment, regardless of temperature. A sensory panel evaluated effects of treatments on appearance quality 7 and 15 days after treatment and on taste quality 4 days after treatment. Judges could not detect any significant differences between anaerobic treatments and control. No significant difference was found in the percent of decayed asparagus among treatments as detected by visual evaluation 6 days after treatment. It appears that exposure to an anaerobic N2 atmosphere for up to 6 hours was not detrimental to the storability or quality of harvested asparagus spears. These results indicate that cooling with vaporized liquid N2, during which an anaerobic atmosphere could be produced before the spears were significantly cooled, would not reduce subsequent quality or storability.

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