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.     

DEVELOPMENT OF THE EGG OF THE MACKEREL AT DIFFERENT CONSTANT TEMPERATURES

1. Mackerel egg development was followed to hatching at constant temperatures of 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, 20°, 21°, 22°, and 24°C. Experiment showed that typical development could be realized only between 11° and 21°. 2. The length of the developmental period increases from 49.5 hours to 207 hours when the temperature is lowered from 21° to 10°C. 3. The calculated µ for the development of the mackerel egg is about 19,000 at temperatures above 15° and approximately 24,900 for temperatures below 15°C. 15° is, apparently, a critical temperature for this process. 4. The calculated values of µ for eight stages of development preceding hatching, i.e. 6 somites, 12 somites, 18 somites, 24 somites, three-quarters circles, four-fifths circles, five-sixths circles, and full circles, are essentially the same as the µ''s for hatching, indicating that the rate of differentiation up to hatching is governed by one process throughout. Critical temperatures for these stages approximate 15°. 5. The total mortality during the incubation period was least at 16°C. where it amounted to 43 per cent. At temperatures above and below this there was a steady increase in the percentage of mortality which reached 100 per cent at 10° and 21°.     

TEMPERATURE CHARACTERISTICS FOR THE METABOLISM OF CHLORELLA : II. THE RATE OF RESPIRATION OF CULTURES OF CHLORELLA PYRENOIDOSA AS A FUNCTION OF TIME AND OF TEMPERATURE

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.).     

CONCERNING THE HEREDITARY ADAPTATION OF ORGANISMS TO HIGHER TEMPERATURE

1. Imagos of Drosophila raised at temperatures of from 12–28.5°C. when placed at any temperature from 15–32.5°C. produce eggs which develop normally at these temperatures. 2. Imagos raised at temperatures of from 29–32.5° and then kept permanently within these temperatures produce eggs which do not develop. 3. Imagos raised at from 28.5–32.5°C. and then placed at temperatures of from 12–25°C. produce eggs which develop normally. 4. Imagos raised at from 28.5–32.5°C. placed at 15–25°C. for 24 hours or longer and then put back into a temperature of from 28.5–32.5°C., produce eggs which will develop at the latter temperature. 5. There is no evidence of any hereditary adaptation to higher temperatures.     

PHYSICOCHEMICAL PROPERTIES OF THE PROTEOLYTIC ENZYME FROM THE LATEX OF THE MILKWEED,ASCLEPIAS SPECIOSA TORR. SOME COMPARISONS WITH OTHER PROTEASES : III. KINETICS OF THE HEAT INACTIVATION OF PAPAIN,BROMELIN, AND ASCLEPAIN

1. The rates of heat inactivation of papain, bromelin, and asclepain were determined at several different temperatures. Papain was by far the most resistant to heat. 2. The destruction of papain at 75–83° and bromelin at 55–70° followed the course of a first order reaction, except that for longer times of heating, bromelin (at 60–70°) was inactivated more rapidly than the first order equation required. 3. The rate of inactivation of asclepain at 55–70° followed the second order equation. 4. The critical thermal increments of inactivation of papain and bromelin, calculated with the van''t Hoff-Arrhenius equation, were of the same high order that has been found for protein denaturation. The increment for asclepain was somewhat lower.     

THE EFFECT OF TEMPERATURE UPON SOME OF THE PROPERTIES OF CASEIN

1. The investigations dealing with the properties of casein as an acid were reviewed. 2. The solubility of uncombined casein in water was measured at 5°C. and found to be 0.70±0.1 mg. of N per 100 gm. of water. 3. Robertson''s solubility measurements of casein in bases at various temperatures were recalculated and found to agree well with more recent measurements. 4. By combining the observations of several investigators, as well as the author''s measurements of the solubility of casein, in base, at various temperatures, the following conclusions were reached: (a) The solubility of casein in base is affected by the temperature in a discontinuous manner. (b) There exist two ranges of temperature, one, extending from about 21° to 37°C. and the other from about 60° to 85°C. where the solubility of casein in base is practically independent of temperature. (c) From 37° to 60° the equivalent combining weight of casein rises from the value 2100 to about 3700 gm. 5. By comparing the values of base bound by 1 gm. of casein at the two temperature ranges with a constant, the value of base necessary to saturate the same amount of casein, it was found that the latter value is a common multiple of the former values, indicating the stoichiometric nature of the effect of temperature.     

THE GROWTH AND DURATION OF LIFE OF CELOSIA CRISTATA SEEDLINGS AT DIFFERENT TEMPERATURES

Daily measurements of hypocotyl length were made on Celosia cristata seedlings cultured in darkness under aseptic conditions at six constant temperatures between 14.5° and 40.5°C. At 40.5° roots did not penetrate the agar and only the hypocotyls that were supported by the wall of the test tube could be measured. The growth curves were of the generalized logistic type, but of different degrees of skewness. The degree of symmetry of the growth curves was influenced by temperature. At the lower temperatures the maximal growth rate came relatively late in the grand period of growth; at successively higher temperatures it came progressively earlier. The mean total time rate of growth (millimeter per diem) was found to be a parabolic function of the temperature. The maximum rate of growth was found from the curve to be at 30.48°C. The maximum observed rate of growth, and the maximum yield, were found to be at 30°C. At all temperatures above 14.5° the maximum growth activity fell in the second quarter of the whole growth period. At all temperatures tested other than 30°, and at all parts of the growth cycle, the growth yield as measured by height of hypocotyl at any given equivalent point was less than at 30°. The total duration of life of the seedlings, and the duration of life after the end of the growth period (intermediate period) were inversely proportional to the mean total growth rate. The observations on Celosia cristata seedlings are thus in accord with the "rate of living" theory of life duration. The optimal temperature for life duration is the minimum temperature, within the range of these observations.     

TIME-TEMPERATURE RELATIONS IN THE INCUBATION OF THE WHITEFISH,COREGONUS CLUPEAFORMIS (MITCHILL)

1. Whitefish eggs incubated in aerated lake water at controlled tempera tures of 0°, 0.5°, 2°, 4°, 6°, 8°, 10°, and 12°C., failed to hatch at either 0° or 12°C. 0.6 per cent hatched alive at 10°C., 72.67 per cent hatched alive at 0.5°C., and an intermediate proportion hatched at intermediate temperatures. 2. The percentage of abnormal embryos which developed to the hatching stage varied directly with temperature between 4° and 12°, all embryos being abnormal at 12°C.; but none were abnormal at either 0.5°, or 2°C. Normal development predominated from 0.5 to 6°C. The highest proportion of embryos to hatch alive was 72.67 per cent at 0.5°C., which is, hence, the optimum temperature. 3. Total incubation time ranged from 29.6 days at 10°C. to 141 days at 0.5°C. 4. The time (T) required to attain any given stage of development is expressed in equations See PDF for Equation where temperature, t, is a negative exponent of the constant, A, whose value differs above or below 6°C., a critical temperature. Values of A above 6° fluctuate about 1.13; those of A below 6° fluctuate about 1.19 as a mean. 5. Applying Arrhenius'' equation µ values for the total incubation period are 27,500 below 6° and 27,100 above it. 6. The relative magnitude of A values of the exponential equation and µ values of Arrhenius'' equation show corresponding changes from one developmental period to another. 7. When plotted, thermal increments show cyclic variations, with maxima during periods of cleavage and of organogenesis. These may indicate the interaction of two separate sets of embryonic processes, which give a maximal response to temperature differences during these two separate periods. 8. Above 6°, µ values during the hatching process are distinct from those of developmental stages and are regarded as being due to the action of hatching enzymes.     

THE RELATION BETWEEN TEMPERATURE AND THE PEDAL RHYTHM OF BALANUS

1. The relation of temperature to the pedal rhythm of Balanus balanoides L. has been studied under otherwise constant conditions. 2. The frequency of movement increases with temperature, showing three groups of thermal increments and three critical temperatures. Five animals yielded µ = 5,700 above 14.5° C. and 12,100 below; 3 gave µ = 7,800 above 9.3° and 22,500 below; while 9 showed µ = 9,500 above 8.1° and 22,100 below. 3. The upper critical temperatures, above which different effects appeared in different animals were 23.4°, 26.0°, and 27.0°. Above 27.0° none of the valves remained open. 4. Excepting the values 5,700 and 9,500, the increments are similar to those previously found to be associated with respiratory and with neuromuscular activities. 5. Dilution of the sea water with from 3 to 4 per cent fresh water decreases the rate without altering the increments. More than 4 per cent dilution causes irregularity.     

THE EFFECT OF TEMPERATURE UPON FACET NUMBER IN THE BAR-EYED MUTANT OF DROSOPHILA : PART III.

Three strains of the bar-eyed mutant of Drosophila melanogaster Meig have been reared at constant temperatures over a range of 15–31°C. The mean facet number in the bar-eyed mutant varies inversely with the temperature at which the larvæ develop. The temperature coefficient (Q₁₀) is of the same order as that for chemical reactions. The facet-temperature relations may be plotted as an exponential curve for temperatures from 15–31°. The rate of development of the immature stages gives a straight line temperature curve between 15 and 29°. Beyond 29° the rate decreases again with a further rise in temperature. The facet curve may be readily superimposed on the development curve between 15 and 27°. The straight line feature of the development curve is probably due to the flattening out of an exponential curve by secondary factors. Since both the straight line and the exponential curve appear simultaneously in the same living material, it is impractical to locate the secondary factors in enzyme destruction, differences in viscosity, or in the physical state of colloids. Differential temperature coefficients for the various separate processes involved in development furnish the best basis for an explanation of the straight line feature of the curve representing the effect of temperature on the rate of physiological processes. Facet number in the full-eyed wild stock is not affected by temperature to a marked degree. The mean facet number for fifteen full-eyed females raised at 27° is 859.06. The mean facet number for the Low Selected Bar females at 27° is 55.13; for the Ultra-bar females at 27° it is 21.27. A consistent sexual difference appears in all the bar stocks, the females having fewer facets. This relation may be expressed by the sex coefficient, the average value of which is 0.791. The average observed difference in mean facet number for a difference of 1°C. in the environment in which the flies developed is 3.09 for the Ultra-bar stock and 14.01 for the Low Selected stock. The average proportional differences in the mean for a difference of 1°C. are 9.22 per cent for Ultra-bar, and 14.51 for Low Selected. The differences in the number of facets per °C. are greatest at the low and least at the high temperatures. The difference in the number of facets per °C. varies with the mean. The proportional differences in the mean per °C. are greatest at the lower (15–17.5°) and higher (29–31°) temperatures and least at the intermediate temperatures. Temperature is a factor in determining facet number only during a relatively short period in larval development. This effective period, at 27°, comes between the end of the 3rd and the end of the 4th day. At 15°, this period is initiated at the end of 8 days following a 1st day at 27°. At 27° this period is approximately 18 hours long. At 15° it is approximately 72 hours long. The number of facets and the length of the immature stage (egg-larval-pupal) appear related when the whole of development is passed at one temperature. That the number of facets is not dependent upon the length of the immature stage is shown by experiments in which only a part of development was passed at one temperature and the remainder at another. Temperature affects the reaction determining the number of facets in approximately the same way that it affects the other developmental reactions, hence the apparent correlation between facet number and the length of the immature stage. Variability as expressed by the coefficient of variability has a tendency to increase with temperature. Standard deviation, on the other hand, appears to decrease with rise in temperature. Neither inheritance nor induction effects are exhibited by this material. This study shows that environment may markedly affect the somatic expression of one Mendelian factor (bar eye), while it has no visible influence on another (white eye).     

STUDIES ON THE LACTASE OF ESCHERICHIA COLI

A "lactase solution" was prepared from Escherichia coli. The mechanism of its action has been studied and changes in the rate of hydrolysis under various conditions investigated. The hydrolysis of lactose by the enzyme approximates the course of reaction of the integrated Michaelis-Menten equation. One molecule of enzyme combines with one molecule of substrate. E. coli lactase is readily inactivated at pH 5.0, and its optimal activity at 36°C. is reached between pH 7.0 and pH 7.5. The optimal temperature for its action was found to be 46°C. when determinations were carried out after an incubation period of 30 minutes. Its inactivation by heat follows the course of a first order reaction, and the critical thermal increment between the temperatures of 45°C. and 53°C. was calculated to be 56,400 calories per mol. The enzyme is activated by potassium cyanide, sodium sulfide, and cysteine, and irreversibly inactivated by mercuric chloride, silver nitrate, and iodine. After inactivation with copper sulfate partial reactivation is possible, while the slight inhibition brought about by hydrogen peroxide is completely reversible. The possible structure of the active groups of E. coli lactase as compared with other enzymes has been discussed.     

THE RATE OF OXYGEN UTILIZATION BY YEAST AS RELATED TO TEMPERATURE

Suspensions of the yeast Saccharomyces cerevisiae gave reproducible rates of O₂ uptake over a period of 6 months. The relation of rate of consumption of O₂ to temperature was tested over a wide range of temperatures, and the constant in the formulation of the relationship is found to be reproducible. The values of this constant (µ) have been obtained for five separate series of experiments by three methods of estimation. The variability of µ has the following magnitudes: the average deviation of a single determination expressed as per cent of the mean is ±2 per cent in the range 30–15°, and ±0.8 per cent in the range 15–3°C. This constancy of metabolic activity measured as a function of temperature can then be utilized for more precise investigations of processes controlling the velocity of oxidations of substrates, and of respiratory systems controlled by intracellular respiratory pigments. The data plotted according to the Arrhemus equation give average values of the constant µ as follows: for the range 35–30°, µ = 8,290; 30–15°, µ = 12,440 ±290; 15–3°, µ = 19,530 ±154. The critical temperatures are at 29.0° and 15.7°C. A close similarity exists between these temperature characteristics (µ) and values in the series usually obtained for respiratory activities in other organisms. This fact supports the view that a common system of processes controls the velocities of physiological activities in yeast and in other organisms.     

THE EFFECT OF TEMPERATURE ON THE LATENT PERIOD IN THE PHOTIC RESPONSE OF MYA ARENARIA

1. The effect of temperature on the reaction time of Mya to light is mainly confined to the latent period. The sensitization period, representing a photochemical process, is changed comparatively little. 2. The relation between the latent period and the temperature is adequately expressed by the Arrhenius equation, for temperatures below 21°C. Above this temperature, the latent period becomes increasingly longer than is required by the Arrhenius formula when µ = 19,680. 3. These deviations, occurring above the highest environmental temperature of Mya, are explained on the assumption that the principal product formed during the latent period is inactivated by heat. 4. Calculation of the velocity of the hypothetical inactivation reaction at different temperatures shows that it also follows the Arrhenius rule when µ = 48,500. This value of µ corresponds to those generally found for spontaneous inactivations and destructions.     

THE KINETICS OF EXCYSTMENT IN COLPODA DUODENARIA

1. Extensive experimental data have been collected on the time required for the excystment process of the small ciliate Colpoda duodenaria throughout a range of temperatures of 8° through 32°C. and a range of concentrations of yeast extract excystment media of 0.08 through 22.4 gm./liter. 2. The excystment process has been separated into two periods, the first inversely proportional to the concentration of the yeast extract and the second independent of its concentration. 3. The first excystment period has been found to depend on the time for diffusion through the protoplasm of a compound from the yeast extract and on the time for a chemical reaction with the extremely high energy of activation of 220,000 calories/mole. 4. The changes in viscosity with temperature for this Colpoda, inferred from diffusion rate changes, have been found to be almost the same as those found by Heilbrunn for Amoeba dubia by the direct method of centrifuging granules. 5. The second excystment period is shown to be controlled by reactions whose apparent activation energies are 44,000 calories/mole below 15°C. and 18,000 calories/mole above 15°C.; above 25°C. this period is independent of temperature. 6. The distribution of the log excystment times of individual organisms about the mean log excystment time is found to be independent of temperature except in the range where the reaction with highest activation energy takes a significant length of time, and to increase rapidly with decreasing temperatures in this range.     

PULSATION OF THE CONTRACTILE VACUOLE OF PARAMECIUM AS AFFECTED BY TEMPERATURE

1. The rate of pulsation of the anterior contractile vacuole of Paramecium caudatum under chloretone anesthesia has been determined over a range of temperatures from 9–31°C. It has been found that the rate is a logarithmic function of the temperature according to the Arrhenius equation. From 9–16° the temperature characteristic (µ) has the value 25,600; from 16–22° it is 18,900; and from 22–31° it becomes 8,600. 2. It is concluded that there are at least three underlying reactions responsible for pulsation, the rates of which vary. Which reaction becomes the limiting one depends upon the range of temperature considered. 3. It does not appear that oxidative processes alone determine the rate of pulsation, although they may be of fundamental importance.     

THE EFFECT OF TEMPERATURE ON THE MECHANICAL ACTIVITY OF THE GILLS OF THE OYSTER (OSTREA VIRGINICA Gm.)

1. The method is described whereby the rate of flow produced by the gills of the oyster can be measured accurately. 2. The rate of doing work in maintaining a constant current along the glass tube can be expressed by the formula W = 2πlµ S ², where W = ergs/sec., l = length of the tube, µ = viscosity in poises, and S = speed at the axis of the tube. 3. The relationship between the rate of doing work and the temperature cannot be described by the equation of Arrhenius. 4. The optimum temperature for the mechanical activity of the gills lies between 25° and 30°C. Below 5° no current is produced, though the cilia are beating. Ciliary motion stops entirely at the freezing temperature of sea water. 5. The factors responsible for the production of current are discussed. The study of the relations between the variability of the rate of flow and the temperature shows that between 15° and 25°C. the absolute variability remains constant and increases considerably above 25° and below 15°. The rôle of the coordination in the production of current is discussed, and the conclusion is reached that coordination is affected by the changes in temperature.     

THE EFFECT OF LOW TEMPERATURE ON THE DEVELOPMENT OF THE LAMELLAR SYSTEM IN CHLOROPLASTS

The influence of low temperature (3°C.) on development of submicroscopic structure in plastids of Zea m. leaves was studied. Leaves from 8-day old etiolated plants, with plastids showing the prolamellar body and few lamellae, were floated for 1 day on tap water both in the dark and in the light, at 26°C and at 3°C. The structures remain unchanged in the dark, independent of temperature. Whereas in the light at 26°C., normal development of parallel compound lamellae and formation of grana occurs, in light at 3°C. ring structures are formed. Under the latter conditions protochlorophyll is converted to chlorophyll, although the in situ absorption maximum is different from the one for chlorophyll in plants grown in light at 26°C. When leaves were transferred from light at 3°C. to light at 26°C., ring structures in the plastids disappeared and normal development occurred. The possibility is discussed that development of parallel-arranged compound lamellae is due both to photochemical and synthetic processes, involving not only accumulation of chlorophyll, but also synthesis of other compounds.     

THE TEMPERATURE CHARACTERISTIC OF RESPIRATION OF AZOTOBACTER

The temperature characteristic of respiration of Azotobacter vinelandii possesses a constant value of 19,330 ± 165 over the temperature range 20–30°C. This value is independent of pH, oxygen tension, age of culture, and other factors within the limits studied. The optimum temperature of respiration is 34–35°C., with limits at about 10° and 50°C.     

THE INFLUENCE OF ENVIRONMENTAL TEMPERATURE ON THE UTILIZATION OF FOOD ENERGY IN BABY CHICKS

1. An optimum of environmental temperature is to be expected for the utilization of food energy in warm blooded animals if their food intake is determined by their appetite. 2. Baby chicks were kept in groups of five chicks in a climatic cabinet at environmental temperatures of 21°, 27°, 32°, 38°, and 40°C. during the period of 6 to 15 days of age. The intake of qualitatively complete food was determined by their appetite. Food intake, excretion, and respiratory exchange were measured. Control chicks from the same hatch as the experimental groups were raised in a brooder and were given the same food as the experimental chicks. The basal metabolism of each experimental group was determined from 24 to 36 hours without food at the age of 16 days. 3. The daily rate of growth increased with decreasing environmental temperature from 2.74 gm. at 40°C. to 4.88 gm. at 21°C. This was 4.2 to 6.5 per cent of their body weight. 4. The amount of food consumed increased in proportion to the decrease in temperature. 5. The availability of the food, used for birds instead of the digestibility and defined as See PDF for Structure showed an optimum at 38°C. 6. The CO₂ production increased from 2.95 liters CO₂ per day per chick at 40°C. to 6.25 liters at 21°C. Per unit of the 3/4 power of the body weight, 23.0 liters CO₂ per kilo^3/4 was produced at 40°C. and 43.4 liters per kilo^3/4 at 21°C. The CO₂ production per unit of 3/4 power of the weight increased at an average rate of approximately 1 per cent per day increase in age. The R.Q. was, on the average, 1.04 during the day and 0.92 during the night. 7. The net energy is calculated on the basis of C and N balances. A maximum of 11.8 Cal. net energy per chick per day was found at 32°C. At 21°C. only 6.9 Cal. net per day per chick was produced and at 40°C. an average of 6.7 Cal. 8. The composition of the gained body substance changed according to the environmental temperature. The protein stored per gram increase in body weight varied from 0.217 to 0.266 gm. protein and seemed unrelated to the temperature. The amount of fat per gram gain in weight dropped from a maximum of 0.153 gm. at 32°C. to 0.012 gm. at 21°C. and an average of 0.107 gm. at 40°C. The energy content per gram of gain in weight had its maximum of 2.95 Cal. per gm. at 38°C. and its minimum of 1.41 Cal. per gm. at 21°C. at which temperature the largest amount of water (0.763 gm. per gm. increase in body weight) was stored. 9. The basal metabolism increased from an average of 60 Cal. per kilo^3/4 at an environmental temperature of 40°C. to 128 Cal. per kilo^3/4 at 21°C. No indication of a critical temperature was found. 10. The partial efficiency, i.e. the increase in net energy per unit of the corresponding increase in food energy, seemed dependent on the environmental temperature, reaching a maximum of 72 per cent of the available energy at 38°C. and decreasing to 57 per cent at 21°C. and to an average of 60 per cent at 40°C. 11. The total efficiency, i.e. the total net energy produced per unit of food energy taken in, was maximum (34 per cent of the available energy) at 32°C., dropped to 16 per cent at 21°C., and to an average of 29 per cent at 40°C.     

TEMPERATURE AND FREQUENCY OF HEART BEAT IN THE COCKROACH

The frequency of pulsation of the intact heart in nymphs (final (?) instar) of Blatta orientalis L. increases with the temperature according to the equation of Arrhenius. The constant µ has typically the same value, within reasonable limits of error, as that (12,200) deduced for other, homologous activities of arthropods where the rate of central nervous discharge is perhaps the controlling element, namely 12,500 ± calories for temperatures 10–38°C. Below a critical temperature of about 10° a change to a higher value of the temperature characteristic occurs, such that µ = 18,100 ±. Exceptionally (one individual) µ = 14,100 ± over the whole range of observed temperature (4.5–28°). The quantitative correspondence of µ for frequency of heart beat in different arthropods adds weight to the conception that this constant may be employed for the recognition of controlling processes.