Taxonomic study of bacteria isolated from natural mineral waters: proposal of Pseudomonas jessenii sp. nov. and Pseudomonas mandelii sp. nov

The taxonomic position of 23 strains isolated from mineral waters and previously grouped in the authentic pseudomonads on the basis of a phenotypic analysis (cluster IX, subclusters XIIIa and XIIIc of VERHILLE, S., ELOMARI, M., COROLER, L., IZARD, D., LECLERC, H. (Syst. Appl. Microbiol, 20, 137-149, 1997) has been genotypically further studied in the present work. On the basis of hybridization results, these strains were gathered into two new genomic groups for which we propose the names of Pseudomonas jessenii sp. nov. (Type strain CIP 105274) and Pseudomonas mandelii sp. nov. (Type strain CIP 105273). Deoxyribonucleic acid relatedness levels showed homologies ranging from 78 to 100% for Pseudomonas jessenii and from 77 to 100% for Pseudomonas mandelii. Furthermore, hybrization rates with 66 representative well characterized species or only partially characterized species of the genus Pseudomonas were below 53%, with delta Tm values of 7 degrees C and more. The mol% G + C content ranged from 57 to 58. The two new species presented basic morphological characteristics common to all pseudomonads. Various phenotypic features, such as denitrification, growth at 4 degrees C or 41 degrees C, trigonelline assimilation, alpha-L-glutamyl-L-histidine arylarmidase activity, growth on benzoate and meso-tartrate were found to differentiate Pseudomonas jessenii from Pseudomonas mandelii and from other Pseudomonas species. Pseudomonas jessenii encompassed a total of 9 strains from both phenotypic groups IX and XIIIa. Pseudomonas mandelii clustered a total of 13 strains from both phenotypic groups IX and XIIIc. Their clinical significance is unknown. The 16S rDNA of each type strain was sequenced and compared with the known sequences of the representative strains of the genus Pseudomonas. A phylogenetic tree was constructed to determine the intrageneric relationships within the genus Pseudomonas.     

Temperature effects on immune response and hematological parameters of channel catfish Ictalurus punctatus vaccinated with live theronts of Ichthyophthirius multifiliis

This study evaluated the influence of temperature on the immune responses and hematological parameters in channel catfish Ictalurus punctatus immunized via intraperitoneal injection with live theronts of Ichthyophthirius multifiliis. Fish were distributed in 18 aquaria and received 9 treatments: 4 groups of fish were vaccinated with live theronts and maintained at constant temperature 15 °C, 20 °C, 25 °C and 30 °C; 3 groups of fish vaccinated and subjected to cycling temperature regime from 15-25 °C, 20-25 °C and 20-30 °C, changed 5 °C each day; 2 groups of fish were not vaccinated and served as controls at 25 °C, one with Ich challenge and the other without challenge. Non vaccinated fish and those vaccinated at 15 °C or 15-25 °C did not show anti-Ich antibodies in the serum 14 and 21 days post-immunization. The antibody levels were significantly higher from fish vaccinated at 25 °C, 30 °C, 20-25 °C and 20-30 °C compared to fish at 15 °C, 20 °C and 15-25 °C both 14 and 21 days post-immunization. At constant water temperature, fish vaccinated at 15 °C showed significantly higher mortality rate (67.8%, P < 0.05) than those vaccinated at 20 °C, 25 °C, and 30 °C (0-10.7% mortalities). At cycling water temperature, fish vaccinated at 15-25 °C showed significantly higher mortality rate (67.8%) than those vaccinated at 20-25 °C and 20-30 °C (P < 0.05). Twenty days after immunization fish vaccinated at 30 °C and 20-30 °C showed significant increase in the red blood cells, white blood cells, thrombocytes and monocytes. Six days after challenge with I. multifiliis theronts the fish showed decreased white blood cells, thrombocytes and monocytes. This study suggests that vaccinated catfish were severely impacted by low temperature, either at 15 °C constant temperature or at 15-25 °C cycling temperature. The fish showed no anti-Ich antibodies and suffered high mortality similar to non vaccinated control fish.     

Lowering storage temperature during ovary transport is beneficial to the developmental competence of bovine oocytes used for somatic cell nuclear transfer

The objective of this study was to determine the effect of storage temperature during ovary transport on the developmental competence of bovine oocytes for use in somatic cell nuclear transfer (SCNT). Ovaries obtained from a slaughterhouse were stored in physiological saline for 3-4h at one of the three temperatures: 15 °C, 25 °C, or 35 °C. The developmental competence of oocytes used for SCNT was ascertained by cleavage and blastocyst formation rate, total cell number, apoptosis index, and the relative abundance of Bax and Hsp70.1 in day 7 blastocysts. Ovaries stored at 35 °C for 3-4h reduced the recovery rate of grade I and II oocytes compared with those stored at 25 °C or 15 °C (45.1±0.7% vs. 76.7±1.2% or 74.8±2.0%, P<0.05). The proportion of oocytes matured to the MII stage (maturation rate) for oocytes stored at 35 °C was significantly lower than those stored at 25 °C or 15 °C (51.3±0.9% vs. 75.1±1.4% or 71.7±1.3%, P<0.05). Cleavage rate (77.7±2.1%, 77.9±1.1% and 72.1±0.7% for 15 °C, 25 °C and 35 °C groups, respectively) and blastocyst formation rate (39.1±0.5%, 36.8±1.4% and 32.2±0.9% for 15 °C, 25 °C and 35 °C groups, respectively) following SCNT were not significantly different between treatments. Oocytes from ovaries stored at 15 °C, however, produced blastocysts with higher cell numbers (97.3±8.6 vs. 80.2±10.8 or 77.4±11.7; P<0.05) and lower apoptotic index (5.1±1.3 vs. 13.5±1.6 or 18.6±1.1, P<0.05) than those stored at 25 °C or 35 °C. The relative abundance of Bax and Hsp70.1 in day 7 blastocysts produced from oocytes derived from ovaries stored at 15 °C was lower than those stored at 25 °C or 35 °C (P<0.05). It was concluded that a storage temperature of 15 °C for a 3-4h period had a significant beneficial effect on the quality and developmental competence of oocytes used for SCNT due to the alleviation of stresses on the oocytes compared with those subjected to storage temperatures of 25 °C or 35 °C.     

Ecophysiology of seed germination in Erythronium japonicum (Liliaceae) with underdeveloped embryos

Erythronium japonicum (Liliaceae) (Japanese name, katakuri) is indigenous to Japan and adjacent Far East regions. We examined their embryo elongation, germination, and seedling emergence in relationship to the temperature. In incubators, seeds did not germinate at 20°/10° (light 12 h/dark 12 h alternating temperature), 20°, 15°, 5°, or 0°C with a 12-h light photoperiod for 200 d. They germinated at 15°/5° or 10°C, starting on day 135. If seeds were kept at 20° or at 25°/15°C before being exposed to 5°C, the seeds germinated, but if kept at 25° or 30°C they did not. Embryos at 25°/15°C grew to half the seed length without germinating; at 0° or 5°C, embryos elongated little. Embryos grew and seeds germinated when kept at 25°/15°C for 90 d and then at 5°C. In the field, seeds are dispersed in mid-June in Hokkaido and in Honshu, mid-May to mid-June. Seeds do not germinate immediately after dispersal because the embryo is underdeveloped. Embryos elongated at medium temperatures in autumn after summer heat, and germination ends in November at 8°/0°C. After germination, seedling emergence was delayed, and most seedlings were observed in early April around the snowmelt when soil cover was 2-3 mm.     

Evidence for a prepore stage in the action of Clostridium perfringens epsilon toxin

Clostridium perfringens epsilon toxin (ETX) rapidly kills MDCK II cells at 37°C, but not 4°C. The current study shows that, in MDCK II cells, ETX binds and forms an oligomeric complex equally well at 37°C and 4°C but only forms a pore at 37°C. However, the complex formed in MDCK cells treated with ETX at 4°C has the potential to form an active pore, since shifting those cells to 37°C results in rapid cytotoxicity. Those results suggested that the block in pore formation at 4°C involves temperature-related trapping of ETX in a prepore intermediate on the MDCK II cell plasma membrane surface. Evidence supporting this hypothesis was obtained when the ETX complex in MDCK II cells was shown to be more susceptible to pronase degradation when formed at 4°C vs. 37°C; this result is consistent with ETX complex formed at 4°C remaining present in an exposed prepore on the membrane surface, while the ETX prepore complex formed at 37°C is unaccessible to pronase because it has inserted into the plasma membrane to form an active pore. In addition, the ETX complex rapidly dissociated from MDCK II cells at 4°C, but not 37°C; this result is consistent with the ETX complex being resistant to dissociation at 37°C because it has inserted into membranes, while the ETX prepore readily dissociates from cells at 4°C because it remains on the membrane surface. These results support the identification of a prepore stage in ETX action and suggest a revised model for ETX cytotoxicity, i) ETX binds to an unidentified receptor, ii) ETX oligomerizes into a prepore on the membrane surface, and iii) the prepore inserts into membranes, in a temperature-sensitive manner, to form an active pore.     

Effect of temperature level on thermal acclimation in Large White growing pigs

The effect of temperature level (24°C, 28°C, 32°C or 36°C) on performance and thermoregulatory response in growing pigs during acclimation to high ambient temperature was studied on a total of 96 Large White barrows. Pigs were exposed to 24°C for 10 days (days -10 to -1, P0) and thereafter to a constant temperature of 24°C, 28°C, 32°C or 36°C for 20 days. Pigs were housed in individual metal slatted pens, allowing a separate collection of faeces and urine and given ad libitum access to feed. Rectal (RT) and cutaneous (CT) temperatures and respiration rate (RR) were measured three times daily (0700, 1200 and 1800 h) every 2 to 3 days during the experiment. From day 1 to 20, the effect of temperature on average daily feed intake (ADFI) and BW gain (average daily gain, ADG) was curvilinear. The decrease of ADFI averaged 90 g/day per °C between 24°C and 32°C and 128 g/day per °C between 32°C and 36°C. The corresponding values for ADG were 50 and 72 g/day per °C, respectively. The 20 days exposure to the experimental temperature was divided in two sub-periods (P1 and P2, from day 1 to 10 and from day 11 to 20, respectively). ADFI was not affected by duration of high-temperature exposure (i.e. P2 v. P1). The ADG was not influenced by the duration of exposure at 24°C and 28°C groups. However, ADG was higher at P2 than at P1 and this effect was temperature dependent (+130 and +458 g/day at 32°C and 36°C, respectively). In P2 at 36°C, dry matter digestibility significantly increased (+2.1%, P < 0.01); however, there was no effect of either duration or temperature on the digestibility of dry matter at group 24°C and 32°C. RT, CT and RR were measured three times daily (0700, 1200 and 1800 h) every 2 to 3 days during the experiment. Between 28°C and 36°C, RT and CT were lower during P2 than during P1 (-0.20°C and -0.23°C; P < 0.05), whereas RR response was not affected by the duration of exposure whatever the temperature level. In conclusion, this study suggests that the effect of elevated temperatures on performance and thermoregulatory responses is dependent on the magnitude and the duration of heat stress.     

Photosynthetic and respiratory acclimation and growth response of Antarctic vascular plants to contrasting temperature regimes

Air temperatures have risen over the past 50 yr along the Antarctic Peninsula, and it is unclear what impact this is having on Antarctic plants. We examined the growth response of the Antarctic vascular plants Colobanthus quitensis (Caryophyllaceae) and Deschampsia antarctica (Poaceae) to temperature and also assessed their ability for thermal acclimation, in terms of whole-canopy net photosynthesis (P(n)) and dark respiration (R(d)), by growing plants for 90 d under three contrasting temperature regimes: 7°C day/7°C night, 12°C day/7°C night, and 20°C day/7°C night (18 h/6 h). These daytime temperatures represent suboptimal (7°C), near-optimal (12°C), and supraoptimal (20°C) temperatures for P(n) based on field measurements at the collection site near Palmer Station along the west coast of the Antarctic Peninsula. Plants of both species grown at a daytime temperature of 20°C had greater RGR (relative growth rate) and produced 2.2-3.3 times as much total biomass as plants grown at daytime temperatures of 12° or 7°C. Plants grown at 20°C also produced 2.0-4.1 times as many leaves, 3.4-5.5 times as much total leaf area, and had 1.5-1.6 times the LAR (leaf area ratio; leaf area:total biomass) and 1.1-1.4 times the LMR (leaf mass ratio; leaf mass:total biomass) of plants grown at 12° or 7°C. Greater RGR and biomass production at 20°C appeared primarily due to greater biomass allocation to leaf production in these plants. Rates of P(n) (leaf-area basis), when measured at their respective daytime growth temperatures, were highest in plants grown at 12°C, and rates of plants grown at 20°C were only 58 (C. quitensis) or 64% (D. antarctica) of the rates in plants grown at 12°C. Thus, lower P(n) per leaf area in plants grown at 20°C was more than offset by much greater leaf-area production. Rates of whole-canopy P(n) (per plant), when measured at their respective daytime growth temperatures, were highest in plants grown at 20°C, and appeared well correlated with differences in RGR and total biomass among treatments. Colobanthus quitensis exhibited only a slight ability for relative acclimation of P(n) (leaf-area basis) as the optimal temperature for P(n) increased from 8.4° to 10.3° to 11.5°C as daytime growth temperatures increased from 7° to 12° to 20°C. There was no evidence for relative acclimation of P(n) in D. antarctica, as plants grown at all three temperature regimes had a similar optimal temperature (10°C) for P(n). There was no evidence for absolute acclimation of P(n) in either species, as rates of P(n) in plants grown at a daytime temperature of 12°C were higher than those of plants grown at daytime temperatures of 7° or 20°C, when measured at their respective growth temperatures. The poor ability for photosynthetic acclimation in these species may be associated with the relatively stable maritime temperature regime during the growing season along the Peninsula. In contrast to P(n), both species exhibited full acclimation of R(d), and rates of R(d) on a leaf-area basis were similar among treatments when measured at their respective daytime growth temperature. Our results suggest that in the absence of interspecific competition, continued warming along the Peninsula will lead to improved vegetative growth of these species due to (1) greater biomass allocation to leaf-area production (as opposed to improved rates of P(n) per leaf area) and (2) their ability to acclimate R(d), such that respiratory losses per leaf area do not increase under higher temperature regimes.     

Developmental times and age-specific life tables for Lygus lineolaris (Heteroptera: Miridae), reared at multiple constant temperatures

Developmental times and survivorship of tarnished plant bug nymphs, Lygus lineolaris (Palisot de Beauvois), and longevity and reproduction of adult tarnished plant bug adults reared on green beans were studied at multiple constant temperatures. The developmental time for each life stage and the total time from egg to adult decreased with increasing temperature. Eggs required the longest time to develop followed by fifth instars and then first-instars. Total developmental time from egg to adult was shortest at 32°C, requiring 18.0 ± 0.3 d and 416.7 ± 31.3 DD above 7.9°C, the estimated minimum temperature for development from egg to adult. Sex did not affect total developmental times and did not affect median survival time. Adults lived significantly fewer days at high temperatures (30-32°C: 17-19 d) compared with temperatures below 30°C (range: 24.5-39.4 d) and the number of eggs laid per day increased from ≈ 4 at 18°C to a maximum of 9.5 eggs per day at 30°C. Total egg production over the lifetime of female tarnished plant bugs increased with temperature reaching a maximum of 175 eggs on average at 27°C, total egg production declined at temperatures above 27°C (30°C: 110.8, 32°C: 77.3 eggs per female). The highest net reproductive rate 74.5 (R(0)) was obtained from insects maintained at 27°C. The intrinsic rate of natural increase (r(m)) increased linearly with temperature to a maximum value of 0.1852 at 30°C, and then decreased at 32°C. Generation and doubling times of the population were shortest at 30°C, 21.0 and 3.7 d, respectively.     

Temperature induces trade-offs between development and starvation resistance in Aedes aegypti (L.) larvae

Heightened temperature increases the development rate of mosquitoes. However, in Aedes aegypti (Diptera: Culicidae), the larvae of which commonly experience limited access to food in urban habitats, temperature effects on adult production may also be influenced by changes in the capacity of larvae to survive without food. We carried out experiments to investigate the effects of temperatures increasing at intervals of 2 °C from 20 °C to 30 °C on the growth, maturation rate and longevity of optimally fed larvae placed in starvation. Overall, both growth rate and starvation resistance were lower in the first three larval instars (L1-L3) compared with L4, in which growth of >75% occurred. Although increasing the temperature reduced the duration of each instar, it had a U-shaped impact in terms of the effect of initial growth on starvation resistance, which increased from L1 to L2 at 20 °C and 30 °C, remained constant at 22 °C and 28 °C, and decreased at 24 °C and 26 °C. Growth from L2 to L3 significantly increased starvation resistance only from 26 °C to 30 °C. Increased temperature (>22 °C) consistently reduced starvation resistance in L1. In L2-L4, increments of 2 °C decreased starvation resistance between 20 °C and 24 °C, but had weaker and instar-specific effects at >24 °C. These data show that starvation resistance in Ae. aegypti depends on both instar and temperature, indicating a trade-off between increased development rate and reduced starvation survival of early-instar larvae, particularly in the lower and middle temperatures of the dengue-endemic range of 20-30 °C. We suggest that anabolic and catabolic processes in larvae have distinct temperature dependencies, which may ultimately cause temperature to modify the density regulation of Ae. aegypti populations.     

Effect of temperature on the progamic phase in high-mountain plants

Progamic processes are particularly temperature-sensitive and, in lowland plants, are usually drastically reduced below 10 °C and above 30 °C. Little is known about how effectively sexual processes of mountain plants function under the large temperature fluctuations at higher altitudes. The present study examines duration and thermal thresholds for progamic processes in six common plant species (Cerastium uniflorum, Gentianella germanica, Ranunculus alpestris, R. glacialis, Saxifraga bryoides, S. caesia) from different altitudinal zones in the European Alps. Whole plants were collected from natural sites shortly before anthesis and kept in a climate chamber until further processing. Flowers with receptive stigmas were hand-pollinated with allopollen and exposed to controlled temperatures between -2 and 40 °C. Pollen performance (adhesion to the stigma, germination, tube growth, fertilisation) was quantitatively analysed, using the aniline blue fluorescence method. Pollen adhesion was possible from -2 to 40 °C. Pollen germination and tube growth occurred from around 0 to 35 °C in most species. Fertilisation was observed from 5 to 30-32 °C (0-35 °C in G. germanica). The progamic phase was shortest in G. germanica (2 h at 30 °C, 12 h at 5 °C, 24 h at 0 °C), followed by R. glacialis (first fertilisation after 2 h at 30 °C, 18 h at 5 °C). In the remaining species, first fertilisation usually occurred after 4-6 h at 30 °C and after 24-30 h at 5 °C. Thus, mountain plants show remarkably flexible pollen performance over a wide temperature range and a short progamic phase, which may be essential for successful reproduction in the stochastic high-mountain climate.     

Walking speed adaptation ability of Myzus persicae to different temperature conditions

Walking speeds were calculated for nine clones of the peach potato aphid Myzus persicae collected from three countries along a latitudinal cline of its European distribution from Sweden to Spain (Sweden, UK and Spain), and the effects of collection origin and intra and intergenerational acclimation were investigated. Walking speeds declined with decreasing temperature, with maximum performance at temperatures closest to acclimation temperature (fastest median walking speed of 5.8 cm min(-1) was recorded for clone UK 3, collected from the UK, at 25°C after acclimating to 25°C for one generation). Following acclimation at both 20°C and 25°C, walking ceased (as indicated by median walking speeds of 0.0 cm min(-1)) at temperatures as high as 7.5°C and 12.5°C. However, acclimation at 10°C enabled mobility to occur to temperatures as low as 0°C. There was no relationship between mobility and latitude of collection, suggesting that large scale mixing of aphids may occur across Europe. However, clonal variation was suggested, with clone UK 3 outperforming the majority of other clones across all temperatures at which mobility was maintained following acclimation at 10°C for one and three generations and at 25°C for one generation. The Scandinavian clones consistently outperformed their temperate and Mediterranean counterparts at the majority of temperatures following acclimation for three generations at 25°C.     

Effects of ambient temperature on adaptive thermogenesis during maintenance of reduced body weight in mice

We showed previously that, at ambient room temperature (22°C), mice maintained at 20% below their initial body weight by calorie restriction expend energy at a rate below that which can be accounted for by the decrease of fat and fat-free mass. Food-restricted rodents may become torpid at subthermoneutral temperatures, a possible confounding factor when using mice as human models in obesity research. We examined the bioenergetic, hormonal, and behavioral responses to maintenance of a 20% body weight reduction in singly housed C57BL/6J +/+ and Lep(ob) mice housed at both 22°C and 30°C. Weight-reduced high-fat-fed diet mice (HFD-WR) showed similar quantitative reductions in energy expenditure-adjusted for body mass and composition-at both 22°C and 30°C: -1.4 kcal/24 h and -1.6 kcal/24 h below predicted, respectively, and neither group entered torpor. In contrast, weight-reduced Lep(ob) mice (OB-WR) housed at 22°C became torpid in the late lights-off period (0200-0500) but did not when housed at 30°C. These studies indicate that mice with an intact leptin axis display similar decreases in "absolute" energy expenditure in response to weight reduction at both 22°C and 30°C ambient temperature. More importantly, the "percent" decrease in total energy expenditure observed in the HFD-WR compared with AL mice is much greater at 30°C (-19%) than at 22°C (-10%). Basal energy expenditure demands are ～45% lower in mice housed at 30°C vs. 22°C, since the mice housed at thermoneutrality do not allocate extra energy for heat production. The higher total energy expenditure of mice housed at 22°C due to these increased thermogenic demands may mask physiologically relevant changes in energy expenditure showing that ambient temperature must be carefully considered when quantifying energy metabolism in both rodents and humans.     

Effects of temperature, relative humidity, absolute humidity, and evaporation potential on survival of airborne Gumboro vaccine virus

Survival of airborne virus influences the extent of disease transmission via air. How environmental factors affect viral survival is not fully understood. We investigated the survival of a vaccine strain of Gumboro virus which was aerosolized at three temperatures (10°C, 20°C, and 30°C) and two relative humidities (RHs) (40% and 70%). The response of viral survival to four metrics (temperature, RH, absolute humidity [AH], and evaporation potential [EP]) was examined. The results show a biphasic viral survival at 10°C and 20°C, i.e., a rapid initial inactivation in a short period (2.3 min) during and after aerosolization, followed by a slow secondary inactivation during a 20-min period after aerosolization. The initial decays of aerosolized virus at 10°C (1.68 to 3.03 ln % min(-1)) and 20°C (3.05 to 3.62 ln % min(-1)) were significantly lower than those at 30°C (5.67 to 5.96 ln % min(-1)). The secondary decays at 10°C (0.03 to 0.09 ln % min(-1)) tended to be higher than those at 20°C (-0.01 to 0.01 ln % min(-1)). The initial viral survival responded to temperature and RH and potentially to EP; the secondary viral survival responded to temperature and potentially to RH. In both phases, survival of the virus was not significantly affected by AH. These findings suggest that long-distance transmission of airborne virus is more likely to occur at 20°C than at 10°C or 30°C and that current Gumboro vaccination by wet aerosolization in poultry industry is not very effective due to the fast initial decay.     

Effect of temperature on immune response of Japanese flounder (Paralichthys olivaceus) to inactivated lymphocystis disease virus (LCDV)

Using flow cytometric analysis, the dynamics of surface immunoglobulin positive (sIg+) cells in lymphoid organs of Japanese flounder (Paralichthys olivaceus) reared at 9, 15, 21 and 26 °C, was investigated following intraperitoneal injection with inactivated lymphocystis disease virus (LCDV). The results showed that the percentages of sIg+ cells were suppressed in peripheral blood leucocytes (PBL), spleen leucocytes (SL) and head kidney leucocytes (HKL) from 9 °C to 15 °C immunized groups, and arrived at their peaks (9 °C: 26.12% in PBL, 18.84% in SL, 17.53% in HKL; 15 °C: 38.82% in PBL, 25.38% in SL, 23.95% in HKL) at 9th and 7th week after immunization, respectively. While the proportions of sIg+ cells in PBL, SL and HKL increased most prominent in the 21 °C group and reached the peaks (54.16% in PBL, 30.32% in SL, 30.23% in HKL) at 5th week. The responses of sIg+ cells from 26 °C group were similar to that from 21 °C group and reached the peaks (35.3% in PBL, 26.24% in SL, 21.83% in HKL) at 5th week. Simultaneously, the kinetics of the specific antibody titer against LCDV in sera was determined. It was shown that the antibody response in the 21 °C group was most prominent and reached the peak earliest. These results indicated inactivated LCDV elicited the most powerful immune response when Japanese flounder maintained at the optimal temperature (21 °C) and obtained the most effective immunization, while the response were suppressed at 9 °C, 15 °C or 26 °C.     

Evidence for reversible change in intensity of prolonged diapause in the chestnut weevil Curculio sikkimensis

The chestnut weevil Curculio sikkimensis undergoes a prolonged larval diapause that is completed by repeated exposure to chilling and warming. We examined the possible reversibility of diapause intensity in response to temperature changes. All larvae were subjected to an initial chilling followed by incubation at 20°C to force pupation of the 1-year-type larvae that require only one winter for diapause completion. We then exposed the larvae remaining in prolonged diapause to a second chilling at 5°C for different lengths of time, preceded or not preceded by incubation at 20°C (moderately high) and/or 25°C (high) and followed by a final post-chilling reincubation at 20°C. Many of the prolonged-diapausing larvae subjected only to a brief second chilling were re-activated upon reincubation. However, short exposure to 25°C before this second chilling dramatically decreased the percentage of larvae completing diapause. When larvae were exposed to 25°C for a short period, then incubated at 20°C and subjected to the brief second chilling, many were re-activated during reincubation. The chilling time required for most of the larvae to complete diapause decreased after pre-chilling incubation at 20°C and increased after incubation at 25°C. These results demonstrate that diapause intensity in C. sikkimensis changes reversibly in response to changes in ambient temperature.     

Use of protein microarray to identify gene expression changes of Yersinia pestis at different temperatures

Yersinia pestis is a bacterium that is transmitted between fleas, which have a body temperature of 26 °C, and mammalian hosts, which have a body temperature of 37 °C. To adapt to the temperature shift, phenotype variations, including virulence, occur. In this study, an antigen microarray including 218 proteins of Y. pestis was used to evaluate antibody responses in a pooled plague serum that was unadsorbed, adsorbed by Y. pestis cultivated at 26 °C, or adsorbed by Y. pestis cultivated at 26 and 37 °C to identify protein expression changes during the temperature shift. We identified 12 proteins as being expressed at 37 °C but not at 26 °C, or expressed at significantly higher levels at 37 °C than at 26 °C. The antibodies against 7 proteins in the serum adsorbed by Y. pestis cultivated at 26 and 37 °C remained positive, suggesting that they were not expressed on the surface of Y. pestis in LB broth in vitro or specifically expressed in vivo. This study proved that protein microarray and antibody profiling comprise a promising technique for monitoring gene expression at the protein level and for better understanding pathogenicity, to find new vaccine targets against plague.     

Effect of Temperature on the Embryogenesis of Geographic Populations of Rotylenchulus reniformis

The effect of temperature on the embryonic development of three populations of reniform nematode (Rotylenchulus reniformis) from the southeastern United States was studied. The development of eggs from single-cell stage to eclosion of second-stage juvenile was monitored at 20, 25, 30, and 35°C. All populations completed embryogenesis in 7 days at 25°C. The greatest differences among populations in time to completion of embryogenesis were observed at 20 and 35°C. Results at the intermediate temperatures (25 and 30°C) were similar for the three populations. The optimal temperature for embryogenesis was calculated to be 31.4°C for the population from Alabama, 28.4°C for the one from Mississippi, and 37.5°C for the one from South Carolina.     

温度对青蒿毛状根生长和青蒿素生物合成的影响

本实验研究了不同温度(15℃～35℃)对青蒿毛状根生长和青蒿素生物合成的影响,发现25℃有利于毛状根生长,30℃促进了青蒿素生物合成。通过温度改变的二步培养技术(培养前20d温度控制在25℃,后10d温度提高到30℃),青蒿素的产量得到明显提高,高于在恒温培养时(25℃或30℃)的结果。     

Effect of temperature on low-strength wastewater treatment by UASB reactor using poly(vinyl alcohol)-gel carrier

The feasibility of treating low-strength wastewater with an up-flow anaerobic sludge blanket (UASB) reactor, using a poly(vinyl alcohol)-gel carrier, at various temperatures and hydraulic retention times (HRTs) was examined. The temperature was decreased from 35°C to 25°C and then to 15°C. The HRT was reduced from 2.0 h to 0.22 h. The COD removal rate reached 28 kg-COD m(-3)d(-1) at 35°C, 16 kg-COD m(-3)d(-1) at 25°C, and 6 kg-COD m(-3)d(-1) at 15°C. The COD removal rate was reduced by half for each temperature reduction of 10°C.