Fluctuating Temperature Treatment Research Articles

Breast Cancer Prevention by Dietary Polyphenols: Microemulsion Formulation and In Vitro Studies

Concerns surrounding breast cancer have been increasing, as it leads to the current global cancer incidence and causes a high mortality rate in women. This study investigated the physiological effects of common dietary polyphenols that might prevent breast cancer progression. Quercetin, kaempferol, and rosmarinic acid were selected to explore their potential bioactivities. Each polyphenol was formulated into a microemulsion to improve its bioactivity and bioavailability. In vitro antioxidant and cytotoxicity activities of the selected polyphenols and their microemulsion forms were further investigated. The optimized microemulsion carrier with 1% oleic acid, 3% ethanol, 10% polysorbate 20, and 86% ultrapure water achieved more than 90% polyphenol encapsulation efficiency. The microemulsion was stable for more than 30 days when encapsulating polyphenol in the fluctuating temperature treatment. In vitro studies suggested that rosmarinic acid-loaded microemulsion had the best antioxidant activity compared with other polyphenol-loaded microemulsions (PL-MEs). Blank microemulsion and all PL-MEs significantly inhibited the proliferation of both hormone-dependent (T47D) and hormone-independent (MDA-MB-231) breast cancer cells. More studies are warranted to confirm the contribution of the microemulsion carrier components to the polyphenols’ improved antioxidant activity and high toxicity of PL-MEs on breast cancer cells.

Short term fluctuating temperature alleviates Daphnia stoichiometric constraints

In this study, we analysed how short term temperature fluctuation interacts with nutrient limitation in the vertical migrating Daphnia commutata. We hypothesize that short term (daily) temperature fluctuation will alleviate nutrient limitation. We carried out experiments analysing growth rates, phosphorus and RNA content of D. commutate grown under four different temperature regimes and two P-limited conditions. Our experiments showed that individuals grown under fluctuating temperature grew more than at the mean temperature. We estimated the expected sizes for the 15 °C treatment based on the Q10 and for the fluctuating temperature treatment. These expected sizes for both treatments resulted well below the observed ones. The P and RNA content of individuals grown at 10 °C were significantly higher than those at 20 °C, and when individuals grown at 10 °C were translocated to 20 °C they exerted an increased growth rate. Our results suggest that, under a regime of diel vertical migration, the temperature alternation would allow migrating organisms to alleviate the effect of severe nutrient limitation maintaining population growth. Under a scenario of global warming, where epilimnetic temperatures will increase, lake temperature will interact with nutrient limitation for consumers, but, organisms may be able to face these changes if they can still regularly move from a cold hypolimnion to a warmer epilimnion.

Effect of constant and fluctuating temperature on the intrapuparial development of Sarcophaga argyrostoma (Robineau-Desvoidy, 1830; Diptera: Sarcophagidae).

This study aimes to investigate the effect of constant and fluctuating temperatures on starting times of developmental periods of insect species. For this purpose, Sarcophaga (Liopygia) argyrostoma (Robineau-Desvoidy, 1830), a forensically important species has been chosen. Whether the constant (25°C) and fluctuating (25.2°C averaged over natural conditions) temperatures would make a difference on the timing of intrapuparial development of this species was investigated. First larval instars were placed in rearing cages until they reached post-feeding third larval instar, which is considered the beginning of intrapuparial development. Relevant morphological changes were observed by hourly dissections. At fluctuating temperature treatment, the post-feeding third instar larvae were transferred to containers under natural, open-air conditions. Minimum and maximum starting times of 23 intrapuparial development periods were determined for both treatments. These times, medians, and standard deviations were compared by Mann-Whitney U tests. Accumulated degree hour values were also calculated for these periods. Regardless of temperature treatment, intrapuparial development periods were similar and adult emergence was observed at 289.5 ( ± 1.52) h under 25°C constant temperature and 319 ( ± 1.41) h under fluctuating temperature conditions. No statistical difference was found between the intrapuparial development of S. argyrostoma reared under constant and fluctuating temperatures, except "pupal-adult apolysis" and "checkered pattern on the abdomen becoming distinct" periods. The use of the results obtained when determining the effect of constant and fluctuating temperatures on the starting times of developmental periods of this species in forensic entomology, is also important in transferring developmental biology data into the field of applied sciences.

A preliminary experiment regarding the natural induction of gonadal development in female Japanese eels without hormone treatment

To test whether gonadal development of female eels could be promoted without any exogenous hormone treatments, we observed the effect of water temperature manipulation. After 3–5 months of water temperature treatments, three silver eels showed higher gonadosomatic indices (GSI). In particular, one eel in the 5–15°C fluctuating temperature treatment group (5°C daytime and 15°C night‐time) had the highest GSI of 8.5 with secondary yolk globule stage oocytes of large diameter (OD; 412 μm) after 3 months, which indicated definite gonadal development compared with those in the initial states (mean GSI, 2.4; OD, 226.7 μm). The 5–15°C fluctuating temperature and constant 5°C groups had low oocyte breakdown (atretic) rates. Because daily temperature fluctuations and cold daytime water are experienced by vertically migrating silver eels in the ocean, these temperature conditions may be key maturation process components that could be useful for hormone‐free artificial maturation.

Effect of storage temperature fluctuation on embryonic development and mortality, and hatchability of broiler hatching eggs.

The effects of temperature fluctuation during 7 d of storage on stage of blastoderm development, embryonic mortality, and hatchability of broiler hatching eggs were studied. Hatching eggs from 2 commercial flocks of Ross 308 broiler breeders at 27 and 50 wk of age, respectively, were randomly assigned to replicate chambers with either a constant temperature (Constant) of 18°C or a temperature that fluctuated (Fluctuated) over a 40min period 3 times daily (0900h, 1300h, and 1700h) between 18°C and 21°C. This latter treatment was intended to mimic the opening of an egg storage room door to add freshly collected eggs. The developmental stages of the blastoderm before and after storage were determined. At each flock age, there were 10 replicate trays of 60 eggs per egg storage temperature treatment set in a single stage incubator. All unhatched eggs were opened and examined macroscopically to determine fertility or embryonic mortality (early dead (0 to 7 d), middle + late dead (8 to 21 d plus pipped eggs), and to calculate percentage hatchability of fertile eggs. Embryonic development was advanced by flock age (P < 0.10) and fluctuating temperature treatment (P < 0.05). Blastoderm stages were determined according to Eyal Giladi and Kockav (EGK). The Fluctuated vs. Constant treatment exhibited an EGK of 9.8 vs. 9.1 (P < 0.05) in the young flock and EGK of 11.0 vs. 10.1 (P < 0.05) in the old flock. During 7 d of storage, Fluctuated temperature decreased early embryonic mortality (P < 0.05) in the eggs from the young flock but increased early embryonic mortality (P < 0.05) in the eggs from the old flock, which decreased (P < 0.05) hatchability of fertile eggs in the old flock. The fluctuating temperature conditions that did not negatively affect the younger flock eggs were not favorable for eggs from the older flock.

Effects of temperature change on physiological and biochemical responses of Yesso scallop, Patinopecten yessoensis

Water temperature can be a significant environmental stressor that affects the physiological and biochemical responses of mollusks. Yesso scallop, Patinopecten yessoensis, is influenced by water temperature fluctuations caused by the Northern Yellow Sea Cold Water Mass. Here, the effects of acute seawater temperature change, gradual temperature change, and fluctuating temperature on the physiological and enzymatic activities in Yesso scallop were studied. Scallops were transferred directly from rearing temperature (15°C) to 5, 10, or 20°C for the acute water temperature change treatment. Scallops in the gradual water temperature change treatment were acclimated to different temperatures (5, 10, and 20°C) by increasing or decreasing seawater temperature progressively (1–2°C/day). The results showed that oxygen consumption and ammonia-N excretion rates in the 20°C-acute water temperature change treatment were significantly higher than those in the gradual treatment (one-way ANOVA, P<0.01). However, scallop ingestion rate decreased significantly in response to an acute water temperature decrease from 15 to 5°C, compared with equivalent groups exposed to a gradual temperature drop (one-way ANOVA, P<0.01). Moreover, hepatopancreatic superoxide dismutase (SOD), catalase (CAT), acid phosphatase (ACP), and lysozyme (LSZ) activities reached their highest levels in the 20°C-acute treatment after 12h. Malondialdehyde (MDA) content increased significantly following the acute water temperature changes and reached the highest level in 10°C-acute treatment after 72h. Heat shock protein70 gene (Hsp70) expression levels also increased significantly when water temperature was increased rapidly from 15 to 20°C or decreased rapidly from 15 to 10°C (P<0.01). In the fluctuation treatment, seawater temperature was altered every 12h for a total of six fluctuations. Scallops were transferred directly from 15 to 7°C (first fluctuation), moved from 7 to 15°C for the next 12h (second fluctuation), and then transferred from 15 to 7°C again (third fluctuation) and so on. As results, significant increases in SOD and CAT activities and MDA content, and decreases in ACP and LSZ activities were observed (one-way ANOVA, P<0.01). Significantly upregulated Hsp70 expression was also found in hemocytes, gills, and the adductor muscle of scallops in the fluctuating temperature treatment (one-way ANOVA, P<0.01). In conclusion, acute water temperature changes and fluctuations impacted the physiological and enzymatic activities of Yesso scallops and upregulated Hsp70 expression.

Effects of environmentally realistic daily temperature variation on pesticide toxicity to aquatic invertebrates

The toxicity of several agricultural chemicals to aquatic invertebrates has been shown to be temperature-dependent, but the role of daily temperature variation has rarely been examined. The authors simulated a natural daily temperature pattern (a fluctuating cycle of 21 °C to 31 °C over a 24-h period) based on field-collected data from Southern High Plains wetlands (TX, USA) and conducted a series of experiments comparing responses from this exposure scenario to a constant exposure at 24 ± 1 °C. Results indicate alterations in pesticide toxicity under the fluctuating temperature regime compared with that of the constant temperature exposure. There was a significant interaction of temperature regime and bifenthrin on Chironomus dilutus survival, and C. dilutus ash-free dry mass was lower in the fluctuating temperature treatment. The 10-d median lethal concentration (LC50) for Hyalella azteca exposed to chlorothalonil was lower under the fluctuating temperature regime compared with the constant temperature regime. For Daphnia magna exposed to malathion, the main effects of temperature regime and malathion were observed on cholinesterase activity. The present study demonstrates how environmentally relevant daily temperature variation influences contaminant effects on aquatic invertebrates.

Fatty acid composition and extreme temperature tolerance following exposure to fluctuating temperatures in a soil arthropod

Ectotherms commonly adjust their lipid composition to ambient temperature to counteract detrimental thermal effects on lipid fluidity. However, the extent of lipid remodeling and the associated fitness consequences under continuous temperature fluctuations are not well-described. The objective of this study was to investigate the effect of repeated temperature fluctuations on fatty acid composition and thermal tolerance. We exposed the springtail Orchesella cincta to two constant temperatures of 5 and 20°C, and a continuously fluctuating treatment between 5 and 20°C every 2 days. Fatty acid composition differed significantly between constant low and high temperatures. As expected, animals were most cold tolerant in the low temperature treatment, while heat tolerance was highest under high temperature. Under fluctuating temperatures, fatty acid composition changed with temperature initially, but later in the experiment fatty acid composition stabilized and closely resembled that found under constant warm temperatures. Consistent with this, heat tolerance in the fluctuating temperature treatment was comparable to the constant warm treatment. Cold tolerance in the fluctuating temperature treatment was intermediate compared to animals acclimated to constant cold or warmth, despite the fact that fatty acid composition was adjusted to warm conditions. This unexpected finding suggests that in animals acclimated to fluctuating temperatures an additional underlying mechanism is involved in the cold shock response. Other aspects of homeoviscous adaptation may protect animals during extreme cold. This paper forms a next step to fully understand the functioning of ectotherms in more thermally variable environments.

Phenotypic Responses of Hatchlings to Constant Versus Fluctuating Incubation Temperatures in the Multi-banded Krait, Bungarus multicintus (Elapidae)

Most studies on egg incubation in reptiles have relied on constant temperature incubation in the laboratory rather than on simulations of thermal regimes in natural nests. The thermal effects on embryos in constant-temperature studies often do not realistically reflect what occurs in nature. Recent studies have increasingly recognized the importance of simulating natural nest temperatures rather than applying constant-temperature regimes. We incubated Bungarus multicintus eggs under three constant and one fluctuating-temperature regimes to evaluate the effects of constant versus fluctuating incubation temperatures on hatching success and hatchling phenotypes. Hatching success did not differ among the four treatments, and incubation temperature did not affect the sexual phenotype of hatchlings. Incubation length decreased as incubation temperature increased, but eggs incubated at fluctuating temperatures did not differ from eggs incubated at constant temperatures with approximately the same mean in incubation length. Of the hatchling phenotypes examined, residual yolk, fat bodies and locomotor performance were more likely affected by incubation temperature. The maximal locomotor speed was fastest in the fluctuating-temperature and 30 degrees C treatments and slowest in the 24 degrees C treatment, with the 27 degrees C treatment in between. The maximal locomotor length was longest in the fluctuating-temperature treatment and shortest in the 24 degrees C and 27 degrees C treatments, with the 30 degrees C treatment in between. Our results show that fluctuating incubation temperatures do not influence hatching success and hatchling size and morphology any differently than constant temperatures with approximately the same mean, but have a positive effect on locomotor performance of hatchlings.

Growth, carcass characteristics, and incidence of ascites in broilers exposed to environmental fluctuations and oiled litter

The effects of diurnal temperature fluctuations and removal of respirable dust, by application of canola oil to straw litter, on growth, carcass traits, and the degree of ascites was evaluated with 1,200 male broilers studied in two replicated 6-wk trials. Each trial used four pens of 150 birds. The temperature treatment consisted of a fluctuation of 3 C in temperature above the required temperature during the day (0600 to 1800 h) and 3 C below the required temperature at night (1800 to 0600 h) for a 6 C change in daily temperature. The control temperature was constant. All pens had the same mean daily temperature. In each trial, one control temperature pen and one fluctuation temperature pen received bi-weekly applications of canola oil to the litter (1.1 L/m2 of oil over 6 wk). At 6 wk of age, 30 birds from each pen were killed for determination of breast muscle, fatpad, and heart weights. All birds were scored for lesions of ascites at time of processing. A score of 0 or 1 represented slight pericardial effusion, slight pulmonary congestion, and edema. A score of 4 represented birds with marked accumulation of ascitic fluid in one or more ceolomic cavities (other than the pericardium) and advanced liver lesions. A cross-sectional image of each 4-mm heart slice (cross-section of the ventricles) was digitally recorded, and with image analysis we determined the right ventricular area (RVA), left ventricular area (LVA), and total heart area (HA). The final BW of the broilers were significantly different, the oiled-litter treatment (2,249 g) had lower weight gain compared with the nonoiled litter treatment (2,293 g). There were no differences in fatpad weight, shank length, lung weight, and percentage breast muscle between the main treatments. The Pectoralis minor and Pectoralis major weight were significantly heavier in the temperature fluctuation treatment than in the control temperature treatment by 3.0 and 12.0 g, respectively. The birds subjected to the control temperature treatment had a lower RVW than the birds subjected to the fluctuating temperature treatment. Temperature fluctuations also resulted in a 1.4% increase in the incidence of mortality. Temperature fluctuations negatively impact broiler growth due to heat loss when litter oiling was excessive.

Effect of temperature fluctuations and food supply on the growth and metabolism of juvenile sea scallops ( Placopecten magellanicus )

On the eastern shore of Nova Scotia late summer atmospheric systems cause upwelling of shelf water; the associated temperature variations of 10 °C with a 6 to 8 d period are comparable in magnitude to the seasonal variation. A laboratory study was undertaken to assess the effects of these temperature fluctuations on sea scallop (Placopecten magellanicus) growth and metabolism. In a factorial design, scallops were subjected to constant (10 °C) or a variable (6 to 15 °C) 8 d temperature cycle, and either a low (seston in filtered seawater) or high (seston supplemented with cultured phytoplankton) food diet. During the 48 d experiment scallop mortality was low and growth positive in all treatments. Shell and total tissue growth rate did not differ between temperature treatments, but growth in the high food treatments was 40 to 50% higher than in the low food treatments. However, soft tissue (excluding adductor) growth did show a temperature treatment effect; growth rates were significantly higher in the fluctuating temperature treatment, due in part to greater gonad development. Weight-standardized rates of scallop oxygen consumption (V sO2 , μmol O2 g−1 h−1) were 20 to 25% higher in high food than in low food treatments, consistent with the expected increase in respiration due to the higher growth rates. Scallop metabolism did not acclimate to the fluctuating temperature cycle; V sO2 and ammonium excretion (V sNH+ 4, μmol O2 g−1 h−1) remained dependent on ambient temperature throughout the experiment. V sNH+ 4 Q10 (2.77) was higher than V sO2 Q10 (2.01) which was reflected in a decrease in the O:N ratio at 15 °C, indicating a shift toward increased protein catabolism and a stressed state. At 10 °C, V sO2 and V sNH+ 4 in the variable temperature treatments were 15 to 18% lower than in the constant temperature treatments, a difference that was not detected in growth measurements. Results demonstrate that the metabolism of Placopecten magellanicus, unlike some bivalve species, is tightly coupled to fluctuations in ambient temperature. Although an absence of compensatory acclimation had a minimal effect on growth in this study, if high temperatures were combined with low food conditions a reduction in scallop production could result.

青果物の温度変動許容度

The effect of fluctuating temperature (square-wave form) on the quality of asparagus, broad bean, edible podded pea, shallot, shii-take mushroom, enoki-take mushroom and ‘Muscat of Alexandria’ grape was investigated, in comparison with those held at a steady temperature. In the fluctuating temperature treatment, materials were kept under the following conditions: fluctuation amplitudes of ±5°C, ±3°C and ±1°C for periods of 12-hours and 6-hours, the standard temperature being 6°C.In asparagus, deterioration of appearance, increase in hardness and decrease of ascorbic acid content were hastened as fluctuating amplitude widened. The fluctuating temperature produced a reduction in quality of broad bean seeds rather than on visual freshness of the pod; browning of the hilum portion was promoted even with an amplitude of ±1°C. Fluctuating temperature did not have so much influence on the deterioration rate of edible podded pea. However, adverse effects of fluctuating temperature were observed in shallot, shii-take and enoki-take, and their deterioration rates were higher under conditions of fluctuating temperatures. While the browning of stems and pedicels of Muscat of Alexandria′ grape was slightly accelerated with fluctuating temperatures, little differences in deterioration rate were found between clusters stored at fluctuating temperatures and those stored at standard temperature of 6°C.From the results above, it is evident that the fluctuating-temperature tolerance of asparagus, broad bean, shallot, shii-take and enoki-take is low and that a steady low temperature is required to retain quality during low temperature storage. The fluctuating-temperature tolerance of edible podded pea and ‘Muscat of Alexandria’ grape is slightly higher than that of the above products and temperature fluctuation during storage is tolerated to a certain extent.

数種野菜の低温障害発生に及ぼす温度変動の影響

The effect of fluctuating temperature on chilling injury in the fruits of eggplant, snap bean, cucumber and sweet pepper was investigated, comparing with those held at steady temperature. In the fluctuating temperature treatment (square-wave form), samples were kept on the fluctuating conditions which were combined with the amplitudes of fluctuation at ±5°C, ±3°C, ±2°C or ±1°C and the periods of onecycle for 24-hour, 12-hour or 6-hour respectively, when standard temperature was 6°C which seemed to occur chilling injury.The decrease in the occurrence of pitting injury of eggplant fruit was directly proportional to the amplitude of the fluctuation and the length of the fluctuating period. The increase in chlorogenic acid content was also delayed as the fluctuating amplitude widened. At a standard temperature of 6°C, the conditions of fluctuating temperature at which chilling injury of eggplant fruit was clearly ameliorated were an amplitude of ±5°C and a period of 12-hour or 24-hour. The fluctuating temperature promoted the amelioration of pitting injury of snap bean fruit as effectively as that of eggplant fruit. It could not, however, be observed that the temperature fluctuation had a positive effect on the amelioration of chilling injury of cucumber fruit and sweet pepper fruit. Although in cucumber fruit pitting injury occurred more often at the fluctuating temperature than at a steady temperature of 6°C, this was probably due to the greater chilling-sensitivity of cucumber fruit compared to eggplant fruit.

Effect of Constant Temperature Treatments Followed by Fluctuating Temperatures on the Softening of Hard Seeds of Trifolium subterraneum L

Three experiments are described in which the effects of constant temperatures ranging from 15 to 80°C, followed by diurnally fluctuating temperatures of 60/15°C were compared on seed softening in three cultivars of T. subterraneum. Constant temperature treatments alone produced relatively few soft seeds, but rapid seed softening ensued within a few days of subsequent fluctuating temperature treatment. The higher and the longer the constant temperature pretreatment, the more soft seeds were obtained. The rate at which this preconditioning of the seed took place was highest in the early stages of exposure to constant temperatures. Differences between cultivars and between temperature treatments were established mainly during this early period of constant temperature treatment. Rates of change of temperature in the 60/15°C fluctuation treatment were important in the final seed softening process: the slower the rate of temperature change the more soft seeds were produced. It is suggested that two distinct temperature dependent processes are involved in seed softening. The first appears to be a thermal degradation process which probably results in weakening of the strophiolar region. Fluctuating temperatures bring about the second stage of softening in which the strophiole is rendered permeable to water.

Sequential softening of hard seeds in burrs of annual medics

Two experiments were done with nine lines from seven species of Medicago to discover if hard seeds softened more easily out of the burr, and whether there was any sequence of softening according to seed position in the burr. It was found that seeds extracted from burrs showed more softening than seeds left in the burrs, when both were given nine months fluctuating temperature treatment (15�- 16�C daily), in M. littoralis, M. scutellata, M, tornata and M. truncatula, but there was no difference in M. polymorpha and M. rugosa. In all lines the seeds softened first at the calyx end of the burr, and then softened in sequence up the burr spiral.