Temperature influence on stable T-DNA integration in plant cells

Four co-cultivation temperatures (15°C, 19°C, 25°C, and 32°C) were evaluated to determine their effects on T-DNA transfer and stable integration. Tobacco leaf explants were co-cultivated with Agrobacterium tumefaciens LBA4404 containing plasmids encoding resistance to the herbicide phosphinothricin, and Bt for insect resistance. Transgenic plants were evaluated for insect and herbicide resistance as well as at the molecular level for foreign gene integration. Even though 19°C has been reported as the optimal temperature for Agrobacterium-mediated gene transfer, co-culture at 25°C led to the highest number of stable transformed plants. Although 19°C may be the best temperature for the Agrobacterium transfer machinery, co-culture at 25°C appears beneficial for plant cell susceptibility to infection and for stable T-DNA insertion into the plant chromosomes.     

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 °C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-κ dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.     

Adaptive Responses to Temperature in Dwarf French Beans, Phaseolus vulgaris L.

The effects of temperature on the growth parameters Net AssimilationRate (E), Relative Leaf Growth Rate (RLGR), Relative GrowthRate (RGR), Specific Leaf Area (SLA), and Leaf Weight Ratio(LWR) in Phaseolus vulgaris L. beans were examined. Rapid changes in SLA invalidate the conventional two-harvestmethod of estimating RGR, and make comparisons between varietiesdifficult The changes in SLA are seen to be due to independent effectsof temperature on RLGR and E, LWR being unaffected. A simple model is described which allows the time-course ofSLA and RGR to be followed by iterative integration on a computer. The results of the simulation suggest that the observed effectsof temperature on RLGR and E are sufficient to predict the changesin SLA and RGR. This should permit more useful comparisons ofgrowth parameters of varieties grown in differing conditionsto be made.     

Quantification of the Role of Acclimation Temperature in Temperature Tolerance of Fishes

The relative effect of acclimation temperature on temperature tolerance was estimated from a geometrical partitioning of the temperature tolerance polygon of a fish species into three distinct zones relative to four key tolerance temperatures. This approach yields a middle tolerance zone which is independent of acclimation temperature bounded by upper and lower acclimation dependent zones. Acclimation dependent and independent temperature tolerance zones can be quantified by either areal or linear methods. Both methods were applied to quantify the effect of acclimation temperature in 21 species of temperate fishes for which temperature tolerance polygons were available. Temperature tolerance polygon areas of these 21 species ranged from 468 to 1380°C² and are linearly related (r ²=0.93, p<0.001) to ultimate incipient upper lethal temperatures. Although areal and linear partitioning methods yielded similar acclimation independent and dependent tolerances, estimates from the areal method incorporates additional information concerning the shape of the temperature tolerance polygon, in particular lower and upper lethal temperature plateaus. Mean combined acclimation dependent and independent tolerance areas of these 21 species were not different, indicating that acclimation effectively doubles the temperature tolerance polygon. Mean lower acclimation dependent area was nearly three times greater than mean upper acclimation dependent area, suggesting that acclimation plays a larger role in tolerance of low rather than high temperatures. Among these 21 species, temperature tolerance of brook charr and sheepshead minnow were the least and most affected by acclimation temperature, respectively.     

Responses of Paramecium to Temperature Change

SYNOPSIS. The effect of temperature on the swimming velocity of Paramecium was investigated. When paramecia cultured at 25 C were transferred to various temperatures, their swimming velocity was increased immediately and then decreased exponentially with time to a new steady velocity. The relaxation time was about 1 min, independent of the new temperature. At a constant temperature the steady velocity was inversely proportional to viscosity. The velocity acceleration was observed when the sudden temperature change was larger than ± 1 C. Its magnitude became constant when the temperature change was greater than several degrees. The steady velocity as a function of temperature had a sharp maximum at the culture temperature and decreased on both sides of this temperature. Incubation of paramecia at 30 C for several hr after cultivation at 25 C shifted the maximum temperature of the steady velocity to 30 C. The temperature at which paramecia gathered in a temperature gradient cell correlated closely with the temperature of the maximum steady velocity.     

Temperature relationship in continous culture

The steady-state and transient behavior of a chemostat-type continuous culture of Aerobacter aerogenes was investigated with special reference to temperature. Experimentally determined kinetic parameters of the fitted steady-state model were found to be strong functions of temperature. The transient response of the culture to a step change in temperature exhibited a dynamic lag whose magnitude depended on the nature and direction of step change.     

Temperature dependence of photosynthesis in cotton

Cotton plants (Gossypium hirsutum L., var. Deltapine Smooth Leaf) were grown under controlled environmental conditions over a range of day/night temperatures from 20/15 to 40/35 C. Their photosynthetic characteristics were then measured over a comparable temperature range. Net photosynthesis tended stongly to be greatest, and intracellular resistance to CO₂ transport to be lowest, when the measurement temperature corresponded to the daytime growth temperature, suggesting pronounced acclimation of the plants to the growth temperature. The preferred growth temperature was close to the 25/20 C regime, since net photosynthesis of these plants, regardless of measurement temperature, was higher and intracellular resistance lower, than in plants from any other regime.     

Preferred Temperature of Meloidogyne incognita

In laboratory thermal gradients, newly hatched infective juveniles of the plant-parasitic root-knot nematode Meloidogyne incognita migrated toward a preferred temperature that was several degrees above the temperature to which they were acclimated. After shifting egg masses to a new temperature, the preferred temperature was reset in less than a day. Possible functions of this type of thermotaxis are discussed, including the use of thermal gradients around plant roots to locate hosts and to maintain a relatively straight path while ranging in the absence of other cues (a collimating stimulus).     

Temperature fluctuations within English lowland ponds

Continuous records were made, for almost two years, of the water temperatures in two ponds in Leicestershire, England. The number of degree-hours and the weekly and monthly mean temperatures were calculated.The water temperature in the ponds and the factors influencing the temperatures were very different in the winter and summer. In the winter the water temperature was fairly uniform, only fluctuating slightly, and was influenced mainly by the air temperature. In the summer the water temperature was very variable within a pond and was mainly influenced by the amount of sunshine received. The range of temperature fluctuation and rate of change within a pond varied inversely with the depth of water, water cloudiness and the amount of plant growth. These internal factors had greatest effects in the summer when the influence of the sun was greatest.The effect of temperature on pond water animals is briefly discussed.

---

Zusammenfassung Während fast zwei Jahren wurden in Leicestershire, England, fortlaufend die Wassertemperaturen von zwei Teichen genommen. Die Zahl der Stedengrade und die wöchentliche und monatliche Durchschnittstemperatur wurden ausgerechnet.Die Wassertemperaturen in diesen Teichen und die Faktoren, die die Temperaturen beeinflussten, waren im Winter und Sommer sehr verschieden. Die Temperaturschwankung war im Winter sehr gering und wurde hauptsächlich durch die Lufttemperatur bedingt. Dagegen war die Temperaturschwankung während des Sommers sehr gross, was hauptsächlich der Quantität von Sonnenschein zu verdanken war. Der Bereich der Temperaturschwankungen und das Mass der Temperaturveränderungen innerhalb eines Teiches waren im umgekehrten Verhältnis zu der Wassertiefe, Wassertrübung und Pflanzenmenge. Diese internen Faktoren sind also im Sommer von grosser Bedeutung, da sie die Wirkung eines zu starken Sonneneinfalls verringern. Auch der Temperatureinfluss auf die Tierwelt des Teiches wird kurz berührt.

     

Response of Chlamydomonas to Temperature Change

SYNOPSIS. Response of Chlamydomonas to temperature change was investigated. When the temperature of the medium was suddenly increased (decreased) the abrupt velocity rise (drop) was observed. This abrupt velocity change was induced immediately after the temperature change. Then, the high (low) level of the velocity was maintained for a few minutes. Finally the velocity decreased (increased), tending to a stationary level at the new temperature with the decay time of a few minutes. The rate of the temperature change determined the magnitude of response. The threshold value was found in the rate of the temperature change to produce the transient change of the velocity. It was ∼ 0.2 C/sec.     

Sensitivity of Paramecium Thermotaxis to Temperature Change

SYNOPSIS. The relationship to swimming velocity of the critical temperature gradient necessary for inducing thermotaxis in Paramecium caudatum was analyzed at various temperatures and viscosities. Since the critical temperature gradient was linearly proportional to the inverse of the swimming velocity, it is concluded that P. caudatum detects temperature changes by locomotion through space and thus exhibits thermotaxis, provided the rate of change is > 0.055 C/sec. The swimming velocity jump was observed when the ciliates were subjected to a stepwise temperature change toward an optimum with a rate > 0.05 C/sec; the jump was not observed, however, when they were subjected to a change toward an unpreferred temperature with the same rate. Hence, thermotaxis can be explained partly by the swimming velocity jump brought about when the cells are swimming toward an optimum temperature in a spatial gradient. It is suggested that thermotaxis might be a direct manifestation of the dynamic properties of membrane as a receptor.     

Modeling of Bacterial Growth with Shifts in Temperature

The temperature of chilled foods is an important variable for the shelf life of a product in a production and distribution chain. To predict the number of organisms as a function of temperature and time, it is essential to model the growth as a function of temperature. The temperature is often not constant in various stages of distribution. The objective of this research was to determine the effect of shifts in temperature. The suitability and usefulness of several models to describe the growth of Lactobacillus plantarum with fluctuating temperatures was evaluated. It can be assumed that temperature shifts within the lag phase can be handled by adding relative parts of the lag time to be completed and that temperature shifts within the exponential phase result in no lag phase. With these assumptions, the kinetic behavior of temperature shift experiments was reasonably well predicted, and this hypothesis was accepted statistically in 73% of the cases. Only shifts of temperature around the minimum temperature for growth showed very large deviations from the model prediction. The best results were obtained with the assumption that a temperature shift (within the lag phase as well as within the exponential phase) results in an additional lag phase. This hypothesis was accepted statistically in 93% of the cases. The length of the additional lag phase is one-fourth of the lag time normally found at the temperature after the shift.     

Varietal Responses to Temperature in Swedes

Four swede varieties and their six F¹ hybrids were grown (for42 d) at different temperatures and also (for 32 d) under differentsoil and air temperature regimes. The weights of the F¹ hybridswere either intermediate to or resembled those of their parents.The varieties appeared to require a 10 °C difference betweenair and soil temperatures for optimal growth. The variety withthe lowest plant weight was Wilby and at low light intensityand under constant air and soil temperature this variety died.All varieties benefited by reduced soil or air temperature althoughthey varied in their optimal requirements. The results indicatedthat temperature x varietal interaction effects might have considerableimportance in the utilization of existing varieties or in thebreeding of new ones.     

Studies on the Low Temperature Fermentation

An attempt has been made to isolate the bacteria capable of accumulating amino acids during the growth at low temperature from various natural sources. A psychrophilic strain P 145 forming glutamic acid at 5°C was obtained and identified as a Brevibacterium sp. The bacterium grew in the range of 0° to 37°C and exhibited the optimum growth at 15°C. The bacterium was defined as a facultative psychrophile.

The strain strictly required methionine only at above 28°C; below this temperature it grew normally without the amino acid. When methionine was added thiamine and biotin stimulated the growth of this strain at 28°C.

With the Brevibacterium sp. P 145 isolated from soil, the effect of incubation temperature on the extracellular amino acid accumulation has been examined from cultural and enzymological points of view. The strain was found to accumulate l-glutamic acid up to 5.88 mg/ml and l-alanine 0.38 mg/ml at 5°C, whereas it formed 0.21 mg/ml of l-glutamic acid and 2.54 mg/ml of l-alanine at 28°C.

The accumulation of l-alanine in the medium at 28°C seemed to be related to the thiamine requirement of the strain. In the case of thiamine deficiency, l-alanine was the main product in the culture at 28°C. When the incubation temperature was abruptly shifted from 28° to 5°C or from 5° to 28°C, the amino acid accumulation was also changed to that of the final temperature. l-Alanine dehydrogenase existed even in the cells grown at 5°C but was not active at this low temperature. These results were in accord with the informations obtained from cultural experiments.     

Influence of Water and Temperature Stress on the Temperature Dependence of the Reappearance of Variable Fluorescence following Illumination

The temperature dependence of the rate and magnitude of the reappearance of photosystem II (PSII) variable fluorescence following illumination has been used to determine plant temperature optima. The present study was designed to determine the effect of a plant's environmental history on the thermal dependency of the reappearance of PSII variable fluorescence. In addition, this study further evaluated the usefulness of this fluorescence technique in identifying plant temperature optima. Laboratory and greenhouse grown potato (Solanum tuberosum L. cv “Norgold M”) plants had a thermal kinetic window between 15 and 25°C. The minimum apparent K_m of NADH hydroxypyruvate reductase for NADH occurred at 20°C. This temperature was also the temperature providing maximal reappearance of variable fluorescence. Soybean (Glycine max [L.] Merrill cv “Wayne”) plants had a thermal kinetic window between 15 and 30°C with a minimum apparent K_m at 25°C. Maximal reappearance of variable fluorescence was seen between 20 and 30°C. To determine if increasing environmental temperatures increased the temperature optimum provided from the fluorescence response curves, potato and soybean leaves from irrigated and dryland field grown plants were evaluated. Although the absolute levels of PSII variable fluorescence declined with increasing thermal stress, the temperature optimum of the dryland plants did not increase with increased exposure to elevated temperatures. Because of variability in the daily period of high temperature stress in the field, studies were initiated with tobacco plants grown in controlled environment chambers. The reappearance of PSII variable fluorescence in tobacco (Nicotiana tabacum L. cv “Wisconsin 38”) leaves that had experienced continuous leaf temperatures of 35°C for 8 days had the same 20°C optima as leaves from plants grown at room temperature. The results of this study suggest that the temperature optimum for the reappearance of variable fluorescence following illumination is not altered by the plant's previous exposure to variable environmental temperatures. These findings support the usefulness of this procedure for the rapid identification of a plant's temperature optimum.     

The Effect of Temperature on Nitrogenase Activity

Acetylene reduction by detached nodules of four non-legumes(Alnus, Hippopha, Myrica, Casuarina), five legumes (Glycine,Lupinus, Pisum, Vicia, Medicago), and two blue-green algae (Anabaena,Plectonema) was tested with respect to the effect of temperatureon nitrogenase activity. In all cases the activity was sensitiveto temperature change, and with the exception of the legumesthere was a simple exponential response to temperature up tothe optimum. The temperature sensitivity of nitrogenase activityin the two blue-green algae was reduced in low light intensities.Temperature data for several other species are compared, anda simple method of correcting for temperature differences suggested.It is emphasized that allowance for the sensitivity of acetylenereduction to temperature differences must be made if field dataare to be used for purposes of comparison.     

Electrocutaneous Sensitivity: Effects of Skin Temperature

The effect of human skin temperature on electrocutaneous sensitivity was examined using brief capacitive discharges. Stimuli were designed to ensure that sensory effects would be independent of skin resistance and would reflect underlying neural excitability as closely as possible. Skin temperature was manipulated by immersing the forearm in circulating hot or cold air. Detection thresholds on the arm and fingertip were raised by cooling, but were not altered by heating. Temperature-related sensitivity shifts were described by the same multiplicative factors for both threshold and suprathreshold levels. The temperature coefficient (Q₁₀) for cutaneous sensitivity under these conditions was approximately 1.3.     

Temperature range variants of Bacillus megaterium

Facultatively and obligately thermophilic variants were isolated from 3 out of 12 tested mesophilic Bacillus megaterium strains. The variants occurred at a frequency of 10^-8–10^-9. The ability to grow at elevated temperatures was cured by means of treatment with acridine orange. Stable revertants were isolated from facultatively and obligately thermophilic variants. An unknown type of megacin was produced by the facultative thermophiles. This megacin attacked mesophilic and obligately thermophilic strains. The thermophiles displayed a few divergent taxonomic characteristics but a close relationship between the strains was indicated by the megacin spectrum and sensitivity to phage. Arrhenius plots revealed that the strains could be considered as temperature range variants and that the temperature characteristic increased with growth at a higher temperature range. The case for a plasmid involvement in the phenomenon is discussed.Abbreviations M Mesophilic - Fp facultatively psychrophilic - Ft facultatively thermophilic - Ot obligately thermophilic     

Temperature Dependence of Memory in Fish3

The influence of temperature on the retention period of a pattern discrimination task (cross versus triangle) was examined on Carassius carassius, Cichlasoma nigrofasciatum and Phoxinus phoxinus. After training at optimal temperature conditions the experimental subjects were kept at a 10 °C lowered temperature, whereas for control subjects there was no temperature change. Tests, carried out every two weeks, showed a significant increase of retention for Carassius c. and Cichlasoma n.; Phoxinus p. showed a slightly more rapid forgetting. These results and investigations of oxygen-uptake indicate a direct dependence of memory processes on the metabolic level.     

Temperature compensation in the mammalian cell cycle

Random and synchronous V79 cells were shifted from 37.5 °C to temperatures between 29 ° and 41 °C. Intermitotic time determinations of random cultures showed an increase in generation time and a broadening in the distribution of generation times in cells whose cycle spanned the temperature shift, but only a slight increase in generation time after one generation at temperatures between 34 °–40 °C. At 33.5 °C and below there was a stepwise increase in generation time. When cells grown at non-standard temperatures were allowed to habituate for 48 h at the altered temperature prior to analysis, the increase in median intermitotic time was slightly less in comparison to analyses done after only one generation following the temperature step. The Q₁₀ for cell division of cells growing at temperatures from 34 ° to 40 °C was between 1.15 and 1.26, suggesting that the mammalian cell cycle is temperature compensated over a limited (6–7 °C) temperature span. Mammalian cells in culture appear to have the same capacity for temperature compensation in their cell cycle as do unicellular eukaryotes. The fact that cycle time at lower temperatures increases in a discrete manner is taken as evidence for a quantal clock.