Chilling Susceptibility of the Blue-green Alga Anacystis nidulans: I. EFFECT OF GROWTH TEMPERATURE

Effects of chilling treatment on the photosynthetic activities and the light-absorption and fluorescence spectra were investigated in intact cells of the blue-green alga Anacystis nidulans that were grown at different temperatures. When the algal cells grown at 38 C were treated at 0 C for 10 minutes, the photosynthesis and the Hill reaction with 1,4-benzoquinone were significantly inactivated and the light-absorption spectrum of carotenoids was modified. These parameters showed very similar temperature dependencies in the chilling susceptibility and the temperature regions critical for the susceptibility depended on the growth temperature. The midpoint values for the critical temperature regions were 4, 6, and 12 C in cells grown at 28, 33, and 38 C, respectively. It is proposed that a common mechanism would underlie the chilling susceptibility of the photosynthesis, the Hill reaction, and the carotenoid absorption spectrum. The decoupling of excitation transfer from allophycocyanin to chlorophyll a at the chilling temperatures occurred very slowly and is attributed to a somewhat different mechanism of the chilling susceptibility.     

TEMPERATURE CHARACTERISTICS FOR THE OXYGEN CONSUMPTION OF GERMINATING SEEDS OF LUPINUS ALBUS AND ZEA MAYS

The rate of oxygen consumption by germinating seeds of Lupinus albus and of Zea mays was studied as a function of temperature (7–26°C.). The Warburg manometer technique was used, with slight modifications. Above and below a critical temperature at 19.5°C. the temperature characteristic for oxygen consumption by Lupinus albus was found to be µ = 11,700± and 16,600 respectively. The same critical temperature was encountered in the case of Zea mays, with temperature characteristics µ = 13,100± above and µ = 21,050 below that temperature.     

TEMPERATURE CHARACTERISTICS FOR THE PRODUCTION OF CO2 BY GERMINATING SEEDS OF LUPINUS ALBUS AND ZEA MAYS

The rates of production of CO₂ by germinating seeds of Lupinus albus and Zea mays were studied between temperatures 12.5° and 25°C. with the HCl-Ba(OH)₂ titration method. The temperature characteristics found are different from those previously obtained for the oxygen consumption of the same seeds germinated in the same manner. For Lupinus, the temperature characteristics above and below the critical temperature of 20° are 16,100 ± and 24,000 ± calories respectively. For Zea, no evidence of a critical temperature was found in this region, and the temperature characteristic is 20,750 ± calories throughout the range of temperature tested. The possible interpretations of the difference in the values of temperature characteristics for oxygen consumption and for production of CO₂ are noted.     

Ethylene Oxide Gaseous Sterilization: I. Concentration and Temperature Effects

The relationships of reaction temperature and concentration of gaseous ethylene oxide to the time required for inactivation of air-dried Bacillus subtilis var. niger spores are more complex than previously reported. A plot of temperature vs. the logarithm of “thermochemical death time” (TCDT) resulted in a straight line between 18 and 57 C for systems of “high” ethylene oxide concentration. The TCDT values were independent of ethylene oxide concentrations above certain temperature-dependent limits. A given ethylene oxide concentration produced a TCDT curve identical in the upper temperature regions with that for higher concentrations. As the temperature was lowered beyond a critical point, this curve diverged from that for higher concentrations, as a straight line of lesser slope. Thus, a series of curves exists for a range of ethylene oxide concentrations. They are characterized by two segments, both logarithmic, intersecting at a critical temperature for each concentration. The intersecting point is at a temperature inversely related to the ethylene oxide gas concentration. The temperature quotient for the high temperature segments of all systems was 1.8. This value was characteristic for ethylene oxide concentrations of 440 and 880 mg/liter at temperatures above 40.6 and 33.4 C, respectively. Below these critical temperatures, the Q₁₀ values for the respective systems were 3.2 and 2.3.     

Biological control of giant salvinia (Salvinia molesta) in a temperate region: cold tolerance and low temperature oviposition of Cyrtobagous salviniae

Success of Cyrtobagous salviniae Calder & Sands (Coleoptera: Curculionidae) for biological control of Salvinia molesta D. S. Mitchell in temperate regions has been less reliable than in tropical and subtropical regions and this difference is presumed to be due to greater winter mortality. We measured the cold tolerance of C. salviniae by comparing chill coma recovery time and survival of adults after exposure to freezing conditions among four geographic populations collected from Florida, Louisiana, Texas and Australia. Effects of winter temperature acclimation on low temperature oviposition also were determined. The Australian population was more cold tolerant than the three US populations. No oviposition by C. salviniae was observed at a water temperature of 17 °C and the oviposition rate at 19 °C was less than at 21, 23 and 25 °C. We suggest that introduction of cold tolerant strains of C. salviniae could increase its effectiveness in temperate regions of the US.     

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.     

Sensitivity of Altitudinal Ecotypes of the Wild Tomato Lycopersicon hirsutum to Chilling Injury

The transition temperature of the leaf polar lipids and the critical temperature for chill-induced inhibition of photosynthesis was determined for three altitudinal ecotypes of the wild tomato Lycopersicon hirsutum. Photosynthesis was measured as CO₂-dependent O₂ evolution at 25°C after leaf slices were exposed to chilling temperatures for 2 hours at a moderate photon flux density of 450 micromoles per square meter per second. The transition temperature of the leaf polar lipids was detected from the change in the temperature coefficient of the fluorescence intensity of trans-parinaric acid. Chill-induced photoinhibition was evident in the three tomato ecotypes when they were chilled below a critical temperature of 10°, 11°, and 13°C, respectively, for the high (LA1777), mid (LA1625), and low (LA1361) altitudinal ecotypes. The temperature differential, below the critical temperature, required to produce a 50% inhibition was also similar for the three ecotypes. A transition was detected in the leaf polar lipids of these plants at a temperature similar to that of the critical temperature for photoinhibition. The results show that the three tomato ecotypes are similar with respect to their critical temperature for chilling-induced photoinhibition and the rate of their response to the chilling stress. They are, thus, similarly sensitive to chilling.     

THERMAL DEPOLARIZATION OF FLUORESCENCE FROM POLYTENE CHROMOSOMES STAINED WITH ACRIDINE ORANGE

The degree of polarization of fluorescence from stretched Chironomus thummi polytene chromosomes, stained with low concentrations of acridine orange (AO), decreases with increasing temperature. The "half temperature" of this decrease (T_½R) is lower than the expected DNA thermal denaturation temperature (T_m) by about 20°C. T_½R is lowered as histone is removed from chromosomes. Balbiani ring regions of the fourth chromosome have T_½R's much lower than other regions, and nearly as low as chromosomes which had been extensively pretreated with trypsin to remove histone and other proteins. Measurements of the thermal change in the rotational diffusion rate of AO in solution with DNA indicate that the temperature at which the DNA-AO bonding changes from a "rigid" to a "loose" mode varies with the GC percentage of the DNA, and in the same fashion as T_m, although 20°C lower.     

Temperature responses of tropical to warm temperateCladophora species in relation to their distribution in the North Atlantic Ocean

The relationship between distribution boundaries and temperature responses of some North AtlanticCladophora species (Chlorophyta) was experimentally examined under various regimes of temperature, light and daylength. Experimentally determined critical temperature intervals, in which survival, growth or reproduction was limited, were compared with annual temperature regimes (monthly means and extremes) at sites inside and outside distribution boundaries. The species tested belonged to two phytogeographic groups: (1) the tropical West Atlantic group (C. submarina: isolate from Curaçao) and (2) the amphiatlantic tropical to warm temperate group (C. prolifera: isolate from Corsica;C. coelothrix: isolates from Brittany and Curaçao; andC. laetevirens: isolates from deep and shallow water in Corsica and from Brittany). In accordance with distribution from tropical to warm temperate regions, each of the species grew well between 20–30°C and reproduction and growth were limited at and below 15°C. The upper survival limit in long days was <35°C in all species but high or maximum growth rates occurred at 30°C.C. prolifera, restricted to the tropical margins, had the most limited survival at 35°C. Experimental evidence suggests thatC. submarina is restricted to the Caribbean and excluded from the more northerly American mainland and Gulf of Mexico coasts by sporadic low winter temperatures in the nearshore waters, when cold northerly weather penetrates far south every few years. Experimental evidence suggests thatC. prolifera, C. coelothrix andC. laetevirens are restricted to their northern European boundaries by summer temperatures too low for sufficient growth and/or reproduction. Their progressively more northerly located boundaries were accounted for by differences in growth rates over the critical 10–15°C interval.C. prolifera andC. coelothrix are excluded or restricted in distribution on North Sea coasts by lethal winter temperatures, again differences in cold tolerance accounting for differences in their distribution patterns. On the American coast, species were probably restricted by lethal winter temperatures in the nearshore and, in some cases, by the absence of suitable hard substrates in the more equable offshore waters. Isolates from two points along the European coast (Brittany, Corsica) ofC. laetevirens showed no marked differences in their temperature tolerance but the Caribbean and European isolates ofC. coelothrix differed markedly in their tolerance to low temperatures, the lethal limit of the Caribbean isolate lying more than 5°C higher (at ca 5°C).     

ON THE TEMPERATURE CHARACTERISTICS FOR FREQUENCY OF BREATHING MOVEMENTS IN INBRED STRAINS OF MICE AND IN THEIR HYBRID OFFSPRING. I

Young mice of a selected line of the dilute brown strain of mice exhibit over the range 15–25°C. (body temperature) a relation of frequency of breathing movements to temperature such that when fitted by the Arrhenius equation the data give a value for the constant µ of 24,000± calories or, less frequently, 28,000±. Young mice of an inbred albino strain show over the range 15–20°C. a value of µ = 34,000±, or, less frequently, 14,000±, with a critical temperature at about 20°C. and a value of µ = 14,000± above 20°C. The F₁ hybrids of these two strains, and the backcross generations to either parent strain, exhibit only those four values of the temperature characteristic observed in the parent strains and none other. One may therefore speak of the inheritance of the value of the constant µ, but the inheritance shows in this instance no Mendelian behavior. Furthermore there appears to be inherited the occurrence (or absence) of a critical temperature at 20°C. These experiments indicate the "biological reality" of the temperature characteristics.     

STIMULATION OF FUNDULUS BY OXALIC AND MALONIC ACIDS AND BREATHING RHYTHM AS FUNCTIONS OF TEMPERATURE

1. Chemical stimulation as a function of temperature was studied by using oxalic acid in fresh and salt water and malonic acid in salt water as stimulating agents on Fundulus. According to the Arrhenius equation the following µ values were obtained for the various acid solutions between 0 and 29°C.: for 0.002N oxalic in fresh water—15,800; 33,000; for 0.0008N oxalic in fresh water—15,800; 33,000; 48,000; for 0.002N oxalic in salt water—19,400; 24,100; 56,500; for 0.004N and 0.002N malonic in salt water—20,600; 65,000. At a critical temperature there is a sharp transition from one thermal increment to another. 2. The chemical processes controlling stimulation do not change with concentration, for different normalities of a single acid yield the same µ values. Distinctly different temperature characteristics were obtained for stimulation by oxalic in salt and fresh water. Likewise stimulation by oxalic and malonic in salt water yielded very different increments. This temperature study indicates that the controlling chemical reactions determining rate of response are different for the same acid in two different environments, or for two dibasic acids in the same environment. Other work indicates, however, that the fundamental stimulation system is the same for all the adds in both environments. Chemical rather than physical processes limit the rate of response since all the values are above 15,000. Stimulation depends upon a series of interrelated chemical reactions, each with its own temperature characteristic. Under varying conditions (e.g. change of temperature, environment, or acid) different chemical reactions may become the slowest or controlling process which determines the rate of response. 3. The variation of response, as measured by the probable error of the mean response time of the fish, is the same function of temperature as reaction time itself. Hence variability is not independent of reaction time and is controlled by the same catenary series of events which determine rate of response to stimulation. 4. Breathing rhythm of Fundulus as related to temperature was studied in both salt and fresh water. In salt water the temperature characteristic is 8,400 while in fresh water it is 16,400 below 9.5°C., and 11,300 above this critical temperature. These µ values are typical of those which have been reported by other workers for respiratory and oxidative biological phenomena. A change in thermal increment with an alteration in environment indicates that different chemical reactions with characteristic velocity constants are controlling the breathing rhythm in salt and fresh water.     

Temperature impact on reproduction and development of congener copepod populations

The goal of this study was to relate the temperature response of all developmental stages and reproductive biology of two congener copepod pairs inhabiting different biogeographic regions to their geographic distribution patterns. Survival of adult females and egg production, embryonic development and hatching success of the genera Centropages and Temora from two stations, in the North Sea and the Mediterranean, were studied in laboratory experiments in a temperature range from 2 to 35 °C. Postembryonic development was determined from cohorts raised at temperatures between 10 and 20 °C with surplus food. Tolerance limits and optima of female survival, reproduction and development distinguished the northern species Centropages hamatus and Temora longicornis from the southern T. stylifera, while C. typicus, which is found in both regions, was intermediate. Thus, thermal preferences could in part explain distribution patterns of these species. While C. hamatus and the two Temora species showed distinct temperature ranges, C. typicus was able to tolerate different temperature conditions, resulting in its wide distribution range from the subarctic to the tropics. However, the thermal range of a species did not necessarily correlate with the optimal temperatures in the experiments. Optima of egg production and stage development were surprisingly low in T. stylifera, which has a mere southern distribution.     

Simulation of C. elegans thermotactic behavior in a linear thermal gradient using a simple phenomenological motility model

The nematode Caenorhabditis elegans has been reported to exhibit thermotaxis, a sophisticated behavioral response to temperature. However, there appears to be some inconsistency among previous reports. The results of population-level thermotaxis investigations suggest that C. elegans can navigate to the region of its cultivation temperature from nearby regions of higher or lower temperature. However, individual C. elegans nematodes appear to show only cryophilic tendencies above their cultivation temperature. A Monte-Carlo style simulation using a simple individual model of C. elegans provides insight into clarifying apparent inconsistencies among previous findings. The simulation using the thermotaxis model that includes the cryophilic tendencies, isothermal tracking and thermal adaptation was conducted. As a result of the random walk property of locomotion of C. elegans, only cryophilic tendencies above the cultivation temperature result in population-level thermophilic tendencies. Isothermal tracking, a period of active pursuit of an isotherm around regions of temperature near prior cultivation temperature, can strengthen the tendencies of these worms to gather around near-cultivation-temperature regions. A statistical index, the thermotaxis (TTX) L-skewness, was introduced and was useful in analyzing the population-level thermotaxis of model worms.     

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.).     

Effect of media composition and growth conditions on production of cellulase and β-glucosidase by a mixed fungal fermentation

The effect of growth temperature, medium composition and pH were examined in shake-flask-scale studies to determine the optimum conditions for cellulase production in mixed cultures of Trichoderma reesei Rut C30 and Aspergillus phoenicis. The optimum temperature and pH were 27°C and pH 4.6. Decreases in medium complexity and cost were achieved through reductions in the concentration of Ca, Mg, and K salts. Ten litre fermentations were implemented to study the kinetics of substrate utilization and product formation. The pH at which the fermentation was controlled appeared to be the critical parameter for batch growth of mixed cultures of Trichoderma reesei Rut C30 and Aspergillus phoenicis.     

Can Tropical Insects Stand the Heat? A Case Study with the Brown Planthopper Nilaparvata lugens (St?l)

The brown planthopper Nilaparvata lugens (Stål) is the most serious pest of rice across the world, especially in tropical climates. N. lugens nymphs and adults were exposed to high temperatures to determine their critical thermal maximum (CT_max), heat coma temperature (HCT) and upper lethal temperature (ULT). Thermal tolerance values differed between developmental stages: nymphs were consistently less heat tolerant than adults. The mean (± SE) CT_max of nymphs and adult females and males were 34.9±0.3, 37.0±0.2 and 37.4±0.2°C respectively, and for the HCT were 37.7±0.3, 43.5±0.4 and 42.0±0.4°C. The ULT₅₀ values (± SE) for nymphs and adults were 41.8±0.1 and 42.5±0.1°C respectively. The results indicate that nymphs of N. lugens are currently living at temperatures close to their upper thermal limits. Climate warming in tropical regions and occasional extreme high temperature events are likely to become important limiting factors affecting the survival and distribution of N. lugens.     

Seed populations of a harmful unarmored dinoflagellate Cochlodinium polykrikoides Margalef in the East China Sea

An unarmored dinoflagellate Cochlodinium polykrikoides has formed red tides responsible for fish mass mortalities especially in coastal areas of western Japan and southern Korea almost every summer to autumn. In laboratory culture, the optimum temperature for growth of the species is ca. 27 °C. Since the species cannot survive in water of temperatures of less than 10 °C, it was considered to over-winter in some certain regions as a motile form or resting cyst, and expand its distribution after the temperature increases to a level tolerable for growth. To determine the over-wintering regions and migration pattern of C. polykrikoides, occurrences of the motile cells were surveyed in the coastal and offshore areas of western Kyushu, Japan and south coast of the Korean Peninsula from April 2006 to August 2008. Cells of C. polykrikoides were found at 14 sites during the investigated period. Motile cells occurred throughout the year in Usuka Bay, Hirado of West Japan. From offshore regions of the Goto Islands and off Shin-Nagasaki Fishing Port, motile cells of C. polykrikoides were first detected from late May, and continuously occurred until February in Nama Bay of the Kami-Goto Islands. This first appearance was before red tides of C. polykrikoides reported at coastal areas in western Kyushu. In Korea, this species was first observed in May and disappeared after October in 2007. These occurrence patterns imply that Usuka Bay in Hirado is one of the over-wintering regions in western Kyushu, and also this species is possibly transported into the northern part of the East China Sea by the Tsushima Warm Current every year.     

Production of Pectate Lyases and Cellulases by Chryseomonas luteola Strain MFCL0 Depends on the Growth Temperature and the Nature of the Culture Medium: Evidence for Two Critical Temperatures

Several extracellular enzymes that are responsible for plant tissue maceration were detected in culture supernatant of the psychrotrophic bacterium Chryseomonas luteola MFCL0. Isoelectrofocusing experiments showed that pectate lyase (PL) activity resulted from the cumulative action of three major isoenzymes, designated PLI, PLII, and PLIII. Cellulolytic activity was also detected in culture supernatants. These enzymes exhibited different behaviors with respect to growth temperature. PLII was not regulated by temperature, whereas PLI and PLIII were regulated similarly by growth temperature. Maximal levels of PLI and PLIII were produced at 14°C when cells were grown in polygalacturonate-containing synthetic medium and at around 20 to 24°C in nutrient broth. In contrast, thermoregulation of cellulolytic activity production differed from thermoregulation of PL. The level of cellulolytic activity was low in all media at temperatures up to 20°C, and then it increased dramatically until the temperature was 28°C, which is the optimal temperature for growth of C. luteola. Previously, we defined the critical temperature by using the modified Arrhenius equation to characterize bacterial behavior. This approach consists of monitoring changes in the maximal specific growth rate as a function of temperature. Our most striking result was the finding that the temperature at which maximum levels of PLI and PLIII were produced in two different media was the same as the critical temperature for growth observed in these two media.     

Effect of temperature on spawning of Penaeus merguiensis

The maturation rate and spawning performance of ablated Penaeus merguiensis were significantly (P<0.05) higher at 27°C than at 23°C. Increasing the temperature from 23°C to 27°C further improved spawning performance (P<0.05), whereas reducing the temperature from 27°C to 23°C impaired spawning. The effect of temperature during the inducing period was more critical than during the holding period. Prawn growth (% of weight gain), however, was not different between 23°C and 27°C over the 60-day experimental period (P>0.05).     

PULSATION FREQUENCY OF THE ADVISCERAL AND ABVISCERAL HEART BEATS OF CIONA INTESTINALIS IN RELATION TO TEMPERATURE

The frequency of pulsation of the heart of Ciona intestinalis increases with temperature in both advisceral and abvisceral direction, according to the Arrhenius equation. The increase in pulsation is the same in both directions. The following µ values were obtained: 8,000–, 12,000+, 16,000, in several combinations, with critical temperatures at 10°, 15°, and 20°C. The values found are comparable with earlier findings for activity of the heart in different animals. This quantitative correspondence suggests anew the conception that temperature characteristics may be employed for recognition of controlling processes. The fact that the µ''s and the critical temperature are the same for advisceral and abvisceral beats, indicates that the general metabolic condition of the two ends of the heart is the same in any one individual.