Relationship between Bacillus sphaericus spore heat resistance and sporulation temperature

Bacillus sphaericus 9602 was grown in batch culture at various temperatures. At 10°C and 12°C the maximum sporulation yield was <10%, while at 15°C, 20°C and 30°C, a sporulation yield of >95% was achieved. However at 40°C B. sphaericus grew only vegetatively. The heat resistances (D values at 90°C) of spores grown at 15°C and 20°C were significantly higher than those grown at 30°C.     

Effect of temperature on the demography of Galerucella birmanica (Coleoptera: Chrysomelidae)

Studies on the effect of temperature on the development of the water chestnut beetle, Galerucella birmanica Jacoby were carried out in the laboratory at seven different temperatures: 16 °C, 19 °C, 22 °C, 25 °C, 28 °C, 31 °C and 34 °C. The developmental time decreased with increase in temperature. The developmental time at 16 °C, 19 °C, 22 °C, 25 °C, 28 °C, 31 °C and 34 °C was 96.60, 80.68, 58.96, 43.48, 35.03, 30.08 and 28.02 days for the period from egg hatching to adult emergence, respectively. The developmental threshold estimated for a generation by linear regression was 10.36 °C. The fecundity per female at 22 °C, 25 °C, 28 °C, 31 °C and 34 °C was 102.3, 134.5, 141.2, 130.1 and 116.2 eggs, respectively. Oviposition period ranged from 15.6 days at 22 °C to 8.6 days at 34 °C. Hatchability of eggs was highest at 31 °C with 76.9% and lowest at 34 °C with 57.1%. The highest generation survival rate was 65.3% at 31 °C, and the intrinsic rate of natural increase ( r _m) for G. birmanica was the highest at 34 °C.     

Prosopis chilensis is a plant highly tolerant to heat shock

At temperatures between 25 and 35°C, 100% of Prosopis chilensis seeds germinated within 24 h. At higher temperatures, the germination rate was reduced; at 50°C, seeds did not germinate. After germination at 25°C, the optimal temperature for seedling growth was 35°C and the seedlings did not grow at a temperature of 50°C. However, when germination was at 35°C, the optimal temperature for seedling growth was 40°C and some seedlings grew at 50°C, suggesting that thermotolerance was induced during seed germination at 35°C. Further thermotolerance can be induced in seedlings germinated at 35°C, by exposing them to 40°C for 2h. Under these conditions, seedlings exhibited increased growth rate at 45 and 50°C. Fluorography of SDS-polyacrylamide gel electrophoresis of the proteins synthesized and accumulated during 2 h at temperatures of 35, 40, 45 and 50°C in the presence of [³⁵S]methionine revealed the expression of 11 proteins not detectable at 35°C. Most of the proteins present at 35°C also increased in expression. The temperature for maximal expression of these proteins was 45°C.     

Influences of Culture Temperature on the Growth, Lipid Content and Fatty Acid Composition of Aurantiochytrium sp. Strain mh0186

The growth, lipid content, and fatty acid composition of Aurantiochytrium sp. strain mh0186 at different temperatures were investigated. Strain mh0186 grew well at 15–30°C, but weakly at 10°C. The biomass at 15–30°C was significantly higher than at 10 and 35°C, and the total lipid at 15–35°C was significantly higher than that at 10°C. The amount of DHA in the total fatty acid was highest at 10°C and decreased in response to temperature increase. The content of DHA (mg/g-dry cell weight) at 15–30°C were significantly higher than those at 35°C and those at 15–25°C were significantly higher than those at 10 and 35°C. The DHA yield at 15–35°C was significantly higher than those at 10 and 35°C. Unsaturation of fatty acid was regulated by temperature and was enhanced in response to temperature decrease. The ratio of DHA to DPA varied at different temperatures.     

The effect of temperature on feeding,growth, and metabolism during the last larval stadium of the female house cricket, Acheta domesticus

Eighth instar female house crickets at 35°C developed faster, gained slightly more wet weight, and consumed less food, water, and oxygen than at 25°C. The duration of the 8th stadium at 25°C was 13 days (undisturbed), but was 14 days when disturbed by daily weighing. The duration of the 8th stadium at 30°C was 8 days and at 35°C was 6 days. During the first half of the 8th stadium at 25, 30, and 35°C, there was a high rate of food and water consumption resulting in statistically equal maximum dry weight achievement (124 mg). Respiratory quotients greater than one during this time indicated the conversion of ingested carbohydrate to fat. During the latter half of the 8th stadium, food and water consumption declined and the crickets lost weight. The period of weight loss was proportionally much longer at 25°C than at 30 or 35°C. Respiratory quotients lower than 1.0 during the latter half of the 8th stadium at 30 and 35°C indicated the metabolism of stored lipids. The respiratory quotient at 25°C never fell below 1.0, possibly because some food remained in the gut. The absorption efficiency was not influenced by temperature (25–35°C). Though the caloric content of the faeces was lower at 25°C than at 30 or 35°C, which correlated to the much longer time for food passage at 25°C than at 35°C, the difference in total calories egested was insufficient to alter the absorption efficiency. A longer period of reduced feeding and greater dry weight loss during the latter half of the 8th stadium at 25°C resulted in a lower metabolic efficiency at 25°C than at 30 or 35°C. Eighth instar crickets in response to a step-function transfer from 30°C–25 or 35°C showed an immediate (<1 hr) and complete metabolic adjustment which was not affected by the temperature history during the 7th stadium. House crickets did not exhibit temperature acclimation in the range 20–40°C, the metabolic rate being determined by ambient temperature. The Q₁₀ for oxygen consumption in the range 20–40°C was about 2.     

Acclimation of photosynthesis, H2O2 content and antioxidants in maize (Zea mays) grown at sub-optimal temperatures

Maize plants were grown at 14, 18 and 20 °C until the fourth leaf had emerged. Leaves from plants grown at 14 and 18 °C had less chlorophyll than those grown at 20 °C. Maximal extractable ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activity was decreased at 14 °C compared with 20 °C, but the activation state was highest at 14 °C. Growth at 14 °C increased the abundance (but not the number) of Rubisco breakdown products. Phosphoenolpyruvate carboxylase (PEPC) activity was decreased at 14 °C compared with 20 °C but no chilling-dependent effects on the abundance of the PEPC protein were observed. Maximal extractable NADP-malate dehydrogenase activity increased at 14 °C compared with 20 °C whereas the glutathione pool was similar in leaves from plants grown at both temperatures. Foliar ascorbate and hydrogen peroxide were increased at 14 °C compared with 20 °C. The foliar hydrogen peroxide content was independent of irradiance at both growth temperatures. Plants grown at 14 °C had decreased rates of CO₂ fixation together with decreased quantum efficiencies of photosystem (PS) II in the light, although there was no photo-inhibition. Growth at 14 °C decreased the abundance of the D1 protein of PSII and the PSI psaB gene product but the psaA gene product was largely unaffected by growth at low temperatures. The relationships between the photosystems and the co-ordinate regulation of electron transport and CO₂ assimilation were maintained in plants grown at 14 °C.     

Effect of temperature on growth,reproduction and survival of the freshwater planorbid snail,Gyraulus convexiusculus,vector of echinostomiasis

Studies were carried out to investigate the effects of 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40° and 45°C on growth, sexual maturity, reproduction and survival of the freshwater planorbid snail, Gyraulus convexiusculus, vector of echinostomiasis, under laboratory conditions. The growth rate of juvenile and sexually mature snails was at minimum at 15°C and was maximum at 35°C. Sexual maturation time was minimum at 35°C and maximum at 20°C. Fecundity was minimum at 15°C and maximum at 35°C. The minimum average and maximum number of eggs per egg capsule was reached at 35°C and lowest at 15°C. 30°C was the optimum temperature for survival of juvenile snails, while sexually mature snails reached maximum survival time at 20°C.     

Effect of temperature on development rate and fecundity of apterous Aphis gossypii Glover (Hom., Aphididae) reared on Gossypium hirsutum L.

The developmental time, survival and reproduction of the cotton aphid, Aphis gossypii Glover (Hom., Aphididae), were evaluated on detached cotton leaves at five constant and two alternating temperatures (15, 20, 25, 30, 35, 25/30, and 30/35°C). The developmental periods of the immature stages ranged from 12.0 days at 15°C to 4.5 days at 30°C. A constant temperature of 35°C was lethal to the immature stages of A. gossypii. The lower developmental threshold for the cotton aphid was estimated at 6.2°C and it required 108.9 degree-days for a first instar to become adult. The average longevity of adult females was reduced from 39.7 days at 15°C to 12.6 days at 30/35°C. The average reproduction rate per female was 51.5 at 25/30°C and 20.9 at 30/35°C. Mean generation time of the population ranged from 10.4 days at 30°C to 24.5 days at 15°C. The largest per capita growth rate ( r _m = 0.413) occurred at 30°C, the smallest at 15°C ( r _m = 0.177). It was evident that temperatures over 30°C prolonged development, increased the mortality of the immature stages, shortened adult longevity, and reduced fecundity. The optimal range of temperature for population growth of A. gossypii on cotton was 25/30–30°C.     

The effect of temperature on the population growth potential of Culex annulirostris Skuse (Diptera: Culicidae)

The effect of temperature on the population growth potential of Culex annulirostris was determined by studying larval growth rate and survival at seven temperatures between 10 and 40°C, and adult survival and fecundity at 20, 25 and 30°C. All larvae died at Wand 40°C; survival was greatest at 25°C. The period for complete juvenile development ranged from 8.57 days (35°C) to 37 days (15°C). Development from egg to adult required 196 day-degrees above 9.7°C with incubation temperatures between 15 and 30°C. Population growth potential was positive at 20, 25 and 30°C, greatest at 25°C, but negative at 15°C. The minimum temperature for population growth was estimated as 17.5°C.     

Heat Shock Response in Hypocotyl of Barley (Hordeum vulgare L.)

In vivo protein synthesis in barley (Hordeum vulgare L.) hypocotyl was maximum at 35°C and 40°C.HPLC analysis of soluble proteins showed 10 different types of proteins, out of which the peak corresponding to retention time 13.3 min was present at 25°C but was absent at 35°C and 40°C. Instead, another peak with retention time 13.7 min was noticed at 35°C and 40°C. Amino acid analysis showed that heat shock resulted in an increase in lysine and histidine and decrease in arginine. Heat shock also resulted in increase in peroxidase, protease and ribonuclease activity at 35°C and 37°C in comparison to 25°C. The incorporation of (3H)-uridine was significantly decreased at 37°C in comparison to 25°C.     

Factors affecting the distribution and dynamics of14C in two soils cropped to barley

The distribution of¹²C and¹⁴C and dynamics of¹⁴C in barley plots were studied after pulse labelling with¹⁴CO₂. Barley was grown in microplots on a Black soil at Ellerslie and a Gray Luvisol at Breton, Alberta and was sampled on four dates between July 31 and October 20. The quantity of¹²C in shoots, microbial biomass, and soil was greater at Ellerslie than Breton. Root¹²C did not differ between sites. There were no significant differences over time in the quantity of¹²C in any of the pools. On the first sampling date 18.59% of the¹⁴C was recovered in the soil-plant system at Ellerslie and 60.82% was recovered at Breton. At Ellerslie 20.35 MBq were recovered in shoots, 0.50 in roots, 0.08 in microbial C and 0.77 in soil while at Breton 27.92 MBq were recovered in shoots, 2.70 in roots, 0.22 in microbial C and 39.3 in soil. The difference between sites in soil¹⁴C was due to higher water filled porosity at Breton than at Ellerslie at the time of labelling. Soluble C (gg^?1 root C), used as a measure of root exuded C, increased above 70% water filled porosity. There were no significant differences over time in the quantity of¹⁴C in any of the pools or in the specific activity of¹⁴CO₂ released from soil during 10-day laboratory incubation. This indicated that the belowground system was in steady state with a continuous input of¹⁴C from labelled root matrial. Differences in specific activity of the various belowground pools revealed that an average of 17% of the microbial C was active at Ellerslie while 43% was active at Breton. Active microbial C (gm^?2) was the same at both sites because total microbial C was lower at Breton than at Ellerslie. At Breton some of the¹⁴C released under conditions of high water filled porosity at the time of labelling appeared to be stabilized against microbial turnover.     

EFFECT OF TEMPERATURE ON THE DEVELOPMENT AND REPRODUCTION OF BEMISIA TABACI B BIOTYPE (HOMOPTERA: ALEYRODIDAE)

Abstract The development, survivorship and reproduction of Bemisia tabaci B biotype on eggplant at seven constant temperatures (17, 20, 23, 26, 29, 32 and 35°C) were studied. The developmental periods from egg to adult varied from 48.7 days at 17°C to 13.9 days at 29°C and the developmental threshold estimated for a generation by linear regression was 12.4°C. The optimum temperature for B. tabaci population growth was 26°C, both extremely low (< 17°C) and high temperature (> 32°C) delayed the development. Survivorships from egg to adult was 67.3% at 26°C, 27.6% and 29.0% at 35°C and 17°C respectively. The average longevity of females ranged from 39.6 days at 20°C to 12.8 days at 35°C. Oviposition per female varied from 164.8 eggs at 20°C to 78.5 eggs at 32°C. Both the longevity and oviposition of B. tabaci females at different temperatures were significantly different ( P < 0.05), and the intrinsic rate of natural increase ( r _m) for B. tabaci at 29°C was the highest.     

The development of Puccinia hordei on barley cv. Zephyr

Germination of uredospores of Puccinia hordei was similar on cover-slips and on the first leaves of barley seedlings (cv. Zephyr) at 100 % r.h. over the range 5–25 °C, being greatest at 20 °C. At 15, 20 and 25 °C maximum germination was attained in 6 h. No uredospores germinated on coverslips in humidities below saturation. The numbers of pustules which subsequently developed on plants incubated at 5, 10, 15 or 18 °C and 100 % r.h. for varying periods up to 24 h, were directly related to rise in temperature and length of incubation. The time from inoculation to eruption of pustules (generation time) was 6 days at 25 °C, 8 days at 20 °C, 10 days at 15 °C, 15 days at 10 °C and 60 days at 5 °C. Pustule production on inoculated plants which had been kept at 5 °C was rapidly accelerated when they were transferred to 20 °C. Data obtained at constant temperatures were used to predict generation times of the fungus in the field. The productivity of pustules, determined as weight of uredospores, was examined at 10, 15 and 20 °C. Significantly more spores were produced at 15 than at 10 °C and most were produced at 20 °C. The results are discussed in relation to those obtained by other workers and to the development of brown rust in the field.     

Effect of constant temperatures on development of the walnut husk fly,Rhagoletis completa

The developmental rates of various life stages ofRhagoletis completa Cresson (Diptera: Tephritidae) were determined in the laboratory at seven different constant temperatures: 8, 12, 16, 20, 24, 28, and 32±1°C, RH 80±10%, photoperiod L 16∶D8. Preoviposition developmental rate was fastest at 28°C (10±1 days, mean±SD) and slowest at 12°C (26±1 days). About 83% of the females deposited eggs at 20 and 24°C and only 25% oviposited at 32°C. Females laid the highest number of eggs at 24°C and the lowest at 8°C. Egg development increased with increasing temperatures up to 28°C, then declined. The fastest egg development was noticed at 28°C (55±1 h) and slowest at 8°C (389±2 h). Over 90% egg hatch was observed at temperatures between 12 and 32°C, but decreased to 73% at 8°C. Larval development was fastest also at 28°C (20±0.2 days). Over 65% pupation was recorded at 20 and 24°C, but decreased to 15% at 32°C and 12% at 8°C. Pupal development was most rapid at 24°C (53±1 days) and slowest at 8°C (162±2 days). More than 70% of adult emergence was noticed in treatments between 16 and 24°C but decreased to 20% at 8°C. Based on a linear regression model of temperature-development rate relationship, the lower developmental thresholds were determined to be 6.6, 5.3, 2.9, and 5°C for preoviposition, egg, larval, and pupal stages, respectively. Based on a non-linear developmental rate model, the upper developmental thresholds were 34°C for preoviposition, egg, and larval stages and 30°C for pupal stage.     

Effect of temperature on translation of mRNA coding for an extracellular proteinase and cell proteins inBacillus megaterium

The content and the half-life of mRNA coding for the Ca²⁺-dependent metalloproteinase were measured by determining the enzyme activity excreted into the medium by cells pregrown in the absence of Ca²⁺ after addition of Ca²⁺ and actinomycin D. The content of the functional proteinase mRNA was highest at 31°C, which is the optimal temperature for the synthesis of this enzyme. Its half-life was 15 min, 7 min, and less than 2 min at 24°, 35°, and 42°C, respectively. Only the third of mRNA molecules synthesized at 31°C was translated in vivo into an active enzyme at 42°C, when compared with the translation proceeding at 24°C. Two-thirds of mRNA molecules synthesized at 31°C were translated into stable cell proteins at 42°C when compared with translation at 24°C. The mean half-life of mRNAs coding for cell proteins was 6–7 min at 24°C, 3 min at 35°C and 2 min at 42°C.     

Rooting of etiolated stem segments of Populus robusta – interaction of temperature, catechol and sucrose in the presence of IAA

Etiolated stem segments of Populus robusta Schneid. were cultured in test solutions each containing 2.0 mg/1 of IAA in combination with varying concentrations of catechol or sucrose or both at 10 ± 2°C, 25 ± 1°C and 35 ± 1°C in the dark. Cuttings did not root in catechol in the presence of IAA alone at 10 ± 2°C. There was no mortality in this culture solution at this temperature. However, cuttings rooted in this culture solution at 25 ± 1°C and 35 ± 1°C and also showed mortality, which was more severe at 35 ± 1°C than at 25 ± 1°C and more severe at higher than at lower concentrations of catechol. Rooting occurred on cuttings in catechol in the presence of IAA and sucrose even at 10 ± 2°C and was strongly promoted at 25 ± 1°C and 35 ± 1°C. The mortality of segments caused by catechol was markedly lowered in the presence of sucrose at these temperatures. Sucrose thus antagonised the toxic effect of catechol.     

Effects of temperature on the growth and reproduction characteristics of Bemisia tabaci B‐biotype and Trialeurodes vaporariorum

The development period, survival rate, longevity and fecundity of two whiteflies, Bemisia tabaci B‐biotype and Trialeurodes vaporariorum (Homoptera: Aleyrodidae) were compared under different temperature laboratory conditions (15°C, 18°C, 21°C and 24°C). Egg development of B. tabaci B‐biotype was significantly longer compared with that of T. vaporariorum at 15°C, 18°C and 24°C. Significantly longer pseudo‐pupae development and lower survival rate were found in B. tabaci B‐biotype at 15°C compared with those at 18°C, 21°C and 24°C. Significantly higher fecundity was found in B. tabaci B‐biotype at 24°C compared with that at 15°C, 18°C and 21°C. However, the fecundity of T. vaporariorum was significantly lower at 24°C relative to that at 15°C, 18°C and 21°C. Significantly shorter 1st instar larval development was found in T. vaporariorum compared with that of B. tabaci at 15°C and 18°C. Significantly longer 2nd instar larval development was found in B. tabaci and T. vaporariorum at 15°C compared with that at 18°C, 21°C and 24°C. However, significantly shorter 3rd instar larval development was found in T. vaporariorum compared with that of B. tabaci at 15°C, 18°C and 24°C. The adaptive divergence of tolerance to relatively low temperature may be an important factor that results in the interspecific differentiation between the seasonal dynamics of these two whiteflies in China.     

High temperature inactivation of cucumber and alfalfa mosaic viruses in Nicotiana rustica cultures

Cucumber mosaic (CMV) and alfalfa mosaic (AlfMV) viruses could not be detected in Nicotiana rustica tissues cultured at 32 °C for 16–18 days or at 40 °C for 5 days, but infectivity remained high in comparable tissue cultured at 22 °C. Incubation of infected cultures at 28–30 °C resulted in an initial reduction followed by a partial recovery in the infectivity of both viruses. The infectivity of CMV in tissues grown between 12 and 32 °C was highest in cultures grown at 12 °C. Although CMV infectivity was not detected in cultures after 16–18 days at 32 °C, virus was eliminated only after a further 30 days at 32 °C. When cultures were transferred from 32 to 22 °C after shorter treatment periods, infectivity rapidly increased to levels higher than those of infected tissues grown continuously at 22 °C. At 40 °C, CMV was eliminated from infected tissues after 9 days and AlfMV after 7 days. Cultures grown continuously at 40 °C deteriorated rapidly but, when grown under diurnal alternating periods of 8 h at 40 °C and 16 h at 22 °C, they remained viable and CMV was also inactivated.     

Temperature Effects on Development and Reproduction of Heterodera cajani on Pigeonpea

Effects of constant and fluctuating temperature on development and reproduction of Heterodera cajani were studied on pigeonpea cv. ICPL 87 in growth chambers at 10, 15, 20, 25, and 30 C and in a greenhouse fluctuating between 22.2 and 37.8 C. Nematode penetration was greatest (P = 0.001) in roots at 25 C; there was no penetration at 10 C. The basal threshold temperature for development was calculated to be 11 C. Completion of one H. cajani generation required 17, 28, 35, and 66 days (323, 392, 315, and 264 degree-days) at 30, 25, 20, and 15 C, respectively, and 19 days (356 degree-days) at a fluctuating temperature. Survival was greater at 20 and 25 C than at 15 and 30 C. The greatest (P = 0.05) number of females (17.9 females per root) were produced at 25 C, compared with 13.2 at 20 C, 7.9 at 30 C, and 2.5 females at 15 C. Nematode reproduction was 1.6 to 7.1 times greater at 25 C than at other temperatures. Emergence of juveniles from egg sacs and cysts was greater at 25 and 30 C than at 15 and 20 C. Equations were developed to predict nematode development rate, cumulative juvenile emergence from egg sacs and cysts, and population increases as influenced by temperature.     

Growth and photosynthesis in seedlings of Hizikia fusiformis (Harvey) Okamura (Sargassaceae, Phaeophyta) cultured at two different temperatures

This study examined temperature acclimation, growth, and photosynthetic characteristics of the zygote-derived seedlings of Hizikia fusiformis (Harvey) Okamura (Sargassaceae). The seedlings were cultured at 15°C or 25°C for 4 weeks. The average relative growth rate was significantly higher in seedlings acclimated at 25°C. The photosynthetic rate measured at 15°C was much higher in seedlings grown at 15°C than those grown at 25°C, indicating photosynthetic acclimation to a lower temperature. At 35°C, the photosynthetic rate of 15°C-grown seedlings was drastically decreased, whereas that of 25°C-grown seedlings was significantly increased. The maximum relative electron transport rate (rETR_max) measured at the respective growth temperature was significantly higher in seedlings grown at 25°C than at 15°C. At a measuring temperature of 35°C, the rETR_max in both 15°C- and 25°C-grown seedlings were considerably reduced with regard to those measured at 15°C or 25°C. Our results suggested that, compared with the seedlings grown at 25°C, those acclimated at a lower temperature could be disadvantaged under adverse conditions such as increased temperatures.