Effects of hot water treatments and storage temperatures on the ripening and the use of electrical impedance as an index for assessing post-harvest changes in mango fruits

The effects of hot water treatment and storage temperature (4°C, 13°C or 22°C) on the quality and impedance of outer and inner mesocarp of mango were assessed in two experiments during storage, impedance being a potential non‐destructive measure of tissue damage following heat treatment. Fruits were subjected to equivalent heat units at 36.5°C for 60 min plus 46.5°C for 43 min or 46.5°C for 90 min by hot water treatments (hwt) on the assumption of cumulative heat effects and a base temperature of 12–13°C. Fruit reflectance decreased whereas chroma and hue angle increased over storage time and also with increase in storage temperature. The yellow colour increased with a rise in storage temperature in hot water treated mangoes. Soluble solids content of mangoes held at 22°C was highest at 5 days of storage but decreased subsequently over storage time. Impedance of all fruits decreased with increase in frequency, storage temperature and time in store. The impedance of hwt mangoes was lower than that of non‐hwt fruits 8 h after immersion, but recovered almost to control levels on day 5 at 4°C or 13°C, but decreased gradually after 5 days at 13°C. Impedance of all mangoes stored at 22°C decreased continuously during storage. Impedance was higher in the inner mesocarp than outer pulp. Impedance of hwt fruits was poorly correlated with soluble solid content and chroma but well correlated with reflectance of fruit pulp at 22°C. Changes in impedance of mangoes are discussed in relation to physiological and biochemical changes that occur during heat treatment and storage.     

Influence of post-flowering temperature on seed development, and subsequent performance of crisp lettuce

Crisp lettuce plants cv. Saladin were grown from the time they started flowering, at 20/10°C (16 h day, 8 h night), 25/15°C and 30/20°C in glasshouses on two occasions in 1985. Yields of seed increased from, on average, 15 g to 27 g and then fell to 20 g per plant with progressive increases in temperature. The number of mature florets per plant increased with temperature but the number of seeds per mature floret was lower at 20/10°C and 30/20°C than at 25/15°C. An increase in temperature reduced mean seed weight by up to 45%, seed volume by 15%, cell numerical volume density (N_v) by 27% and the number of cells per seed by 39%. Percentage seed germination reached a maximum early in seed development at the stage when the pappus appeared through the involucral bracts. Differences in percentage germination and vigour of seeds (slope test) from different temperatures were accounted for largely by the effects on mean seed weight. However, when germinated at 30°C seeds produced at 30/20°C germinated more readily than those produced at 25/15°C or 20/10°C. Seed vigour gradually increased with an increase in the length of storage after harvest, reaching a maximum after 260 days. In general, seeds produced at 25/15°C exhibited a greater variation in numbers of seeds per floret, N_v, seed weight, times of seedling emergence, seedling and mature head weight than seeds produced at lower or higher temperatures.     

Photoperiod and root-zone temperature: Interacting effects on growth and mineral nutrients of maize

Factorial effects of photoperiod (6, 12 and 18 h) and root-zone temperatures (9, 15 and 21°C) on the growth and mineral nutrient concentration and partitioning in maize (Zea mays L.) were investigated. Strong interactions were observed between photoperiod and root-zone temperature on the growth and concentration of numerous mineral elements in the plant tops and roots. For example, a threefold increase in photoperiod (from 6 to 18 h) did not affect the growth of tops or roots if the root-zone temperature was 9°C but increased them each by eightfold if the root-zone temperature was 21°C. On the other hand, raising the root-zone temperature from 9 to 21°C increased the growth of tops and root each by ca. threefold when plants were grown with 6 h of light. At 18 h photoperiod, however, plant growth was increased 20- to 30-fold by the same rise in the root-zone temperature. The concentrations of different mineral elements in the roots and tops were affected quite differently by the interacting effects of photoperiod and root-zone temperature. In general, increasing the photoperiod at a given root-zone temperature decreased the concentrations of elements while increasing the root-zone temperature at a given photoperiod increased the concentrations of most elements in both roots and tops. The exceptions were K and B which reacted opposite to each other: K concentration in both tops and roots was relatively insensitive to photoperiod but very sensitive to root-zone temperature and the reverse was true for boron. The relative insensitivity of plant growth to increased day length as long as the roots are subjected to suboptimal (low) soil temperatures may have survival significance and point to the predominant role of root temperature over that of day length in the early growth of maize. A possible mechanism by which photoperiod and root-zone temperature might interactively alter the nutrient uptake by the roots is discussed.     

The effects of photoperiod and temperature on calling behaviour and egg development of the bertha armyworm,Mamestra configurata (Lepidoptera: Noctuidae)

The effects of photoperiod and temperature on calling behaviour and the effects of temperature on the relationship between egg development and calling of virgin females of Mamestra configurata Walker were examined at 3 photoperiodic regimes and seven constant temperatures. Photoperiod affected the diel periodicity of calling and length of the daily calling period. The mean onset calling times were similar if the preceding scotophase(s) was 6–10 h long, but the onset of calling was delayed by 1–5 h if the preceding scotophase(s) was 12–18 h long. Long-term, constant temperature (from emergence until death) affected 4 aspects of calling: age at first calling, diel periodicity, length of the daily calling period, and percentage of females calling. Short-term temperature changes (during a single scotophase) affected calling in 3 ways: diel periodicity, length of the daily calling period, and percentage of females calling. The optimal temperature range for calling was, at least, 10–25°C; the upper limit and threshold were near 35 and < 5°C. The time of first calling was synchronized closely with the appearance of the first chorionated eggs in the ovaries at 10–35°C. Egg development and calling were adversely affected at 30 and 35°C. The physiological and ecological significance of the data are discussed.     

Rapid evolution of sperm length in response to increased temperature in an ectothermic fish

The Intergovernmental Panel on Climate Change predicts an average global temperature increase of 1.8–4.0 °C by 2100. Tropical ectotherms are expected to be particularly sensitive to this temperature increase because they live close to their thermal limits. We investigated the phenotypic plasticity and evolutionary response of sperm traits in guppies (Poecilia reticulata) to increased temperatures after 6, 18, and 24 months. Guppies with evolution temperatures of 25 °C (control) or 28 °C were reared in either 25 or 28 °C in a 2 × 2 common garden design. The plastic response to increased temperature was a decreased sperm length, velocity, and path linearity. The evolutionary response was a subsequent increase in sperm length, resulting in complete compensation after just 6 months (at most four generations) in 28 °C water. Sperm velocity and linearity showed no sign of evolution even after 24 months. This study provides evidence that some reproductive traits can respond via rapid evolution to the temperature increase associated with climate change.     

The influence of housefly Musca domestica embryo age on viability in water and at low temperatures

The sensitivity of housefly Musca domestica L. (Diptera: Muscidae) embryos to storage at low temperatures (5 and 10 °C on moist sponges in Petri dishes) and in water at 26 °C was investigated to develop suitable protocols for the storage and transport of housefly eggs. The youngest embryos (aged 0–3 h) were the most sensitive to storage at 5 °C, with 45% survival after storage for 24 h. Storage of embryos aged 3–12 h at 5 °C for 24 h had no negative effect; longer storage resulted in significantly decreased larval survival (30–34% after 48–72 h, compared with 61% in the control group) and reduced hatching rates (83% after 72 h storage). No negative effects were observed when embryos aged 0–9 h were stored at 10 °C for 24 h, but this temperature did not completely inhibit development and eggs began to hatch if stored for longer than 24 h. All age groups of embryos showed high mortality after storage in water at 26 °C for 24 h, with the youngest embryos being least resistant to submersion.     

Predicting the stabilities of freeze-dried suspensions of Lactobacillus acidophilus by the accelerated storage test

The elevated temperatures of 50 ° C, 60 ° C, and 70 ° C were used in an accelerated storage test for predicting the stability of freeze-dried suspensions of L. acidophilus. The logarithmic death of bacteria at the above temperatures and the Arrhenius relationship obtained permitted predicting the rate of death at any storage temperature. The values predicted for storage stability of freeze-dried suspensions of L. acidophilus at 4 ° C and 20 ° C were confirmed by the actual values obtained after storage at these temperatures for 6, 15, and 19 mo.     

Divergent cytokine response following maximum progressive swimming in hot water

Exercise promotes transitory alterations in cytokine secretion, and these changes are affected by exercise duration and intensity. Considering that exercise responses also are affected by environmental factors, the goal of the present study was to investigate the effect of water temperature on the cytokine response to maximum swimming. Swiss mice performed a maximum progressive swimming exercise at 31 or 38 °C, and plasma cytokine levels were evaluated immediately or 1, 6 or 24 h after exercise. The cytokine profile after swimming at 31 °C was characterized by increased interleukin (IL)‐6 and monocyte chemotactic protein‐1 (MCP‐1) levels, which peaked 1 h after exercise, suggesting an adequate inflammatory milieu to induce muscle regeneration. Transitory reductions in IL‐10 and IL‐12 levels also were observed after swimming at 31 °C. The cytokine response to swimming was modified when the water temperature was increased to 38 °C. Although exercise at 38 °C also led to IL‐6 secretion, the peak in IL‐6 production occurred 6 h after exercise, and IL‐6 levels were significantly lower than those observed after maximum swimming at 31 °C (p = 0·030). Furthermore, MCP‐1 levels were lower and tumour necrosis factor‐α levels were higher immediately after swimming at 38 °C, suggesting a dysregulated pro‐inflammatory milieu. These alterations in the cytokine profile can be attributed in part to reduced exercise total work because exhaustion occurred sooner in mice swimming at 38 °C than in those swimming at 31 °C. Copyright © 2011 John Wiley & Sons, Ltd.     

The influence of temperature on weight loss from stored onion bulbs due to desiccation, respiration and sprouting

When onion bulbs were stored for 9 months at 2, 7.5, 15 or 25 °C and 70% r.h., the losses due to desiccation increased with temperature but less than 20 % was due to respiration at any of the storage temperatures. Respiration rates of onion bulbs transferred from 2 to 25 °C were higher from February onwards than those of bulbs stored continuously at 25 °C. Conversely, bulbs transferred from 25 to 2 °C respired less from February onwards than those kept at 2 °C. Sprouting, at the final assessment in June, was highest at 15 and 7.5 °C and lowest at 2 °C. Total weight loss was above 45 % in all the storage treatments except at 2 °C (12%). Storage at 7.5 °C is suitable until March but long-term storage until June requires low temperatures.     

Destabilization of mayonnaise induced by lipid crystallization upon freezing

The thermal and rheological history of mayonnaise during freezing and its dispersion stability after the freeze-thaw process were investigated. Mayonnaise was cooled to freeze and stored at ?20 to ?40 °C while monitoring the temperature; penetration tests were conducted on the mayonnaise, which was sampled at selected times during isothermal storage at ?20 °C. Significant increases in the temperature and stress values due to water-phase crystallization and subsequent oil-phase crystallization were observed. The water phase crystallized during the cooling step in all the tested mayonnaise samples. The oil phases of the prepared mayonnaise (with rapeseed oil) and commercial mayonnaise crystallized during isothermal storage after 6 and 4 h, respectively, at ?20 °C. The dispersion stability was evaluated from the separation ratio, which was defined as the weight ratio of separated oil after centrifuging to the total amount of oil in the commercial mayonnaise. The separation ratio rapidly increased after 4 h of freezing. This result suggests that crystallization of the oil phase is strongly related to the dispersion stability of mayonnaise.     

Preservation of Phakopsora pachyrhizi Uredospores

This study compared different temperatures and dormancy‐reversion procedures for preservation of Phakopsora pachyrhizi uredospores. The storage temperatures tested were room temperature, 5°C, ?20°C and ?80°C. Dehydrated and non‐dehydrated uredospores were used, and evaluations for germination (%) and infectivity (no. of lesions/cm²) were made with fresh harvested spores and after 15, 29, 76, 154 and 231 days of storage. The dormancy‐reversion procedures evaluated were thermal shock (40°C/5 min) followed or not by hydration (moist chamber/24 h). Uredospores stored at room temperature were viable only up to a month of storage, regardless of their hydration condition. Survival of uredospores increased with storage at lower temperatures. Dehydration of uredospores prior to storage increased their viability, mainly for uredospores stored at 5°C, ?20°C and ?80°C. At 5°C and ?20°C, dehydrated uredospores showed increases in viability of at least 47 and 127 days, respectively, compared to non‐dehydrated spores. Uredospore germination and infectivity after storage for 231 days (7.7 months), could only be observed at ?80°C, for both hydration conditions. At this storage temperature, dehydrated and non‐dehydrated uredospores exhibited 56 and 28% of germination at the end of the experiment, respectively. Storage at ?80°C also maintained uredospore infectivity, based upon levels of infection frequency, for both hydration conditions. Among the dormancy‐reversion treatments applied to spores stored at ?80°C, those involving hydration allowed recoveries of 85 to 92% of the initial germination.     

Effect of exercise-induced hyperthermia on serum iron concentration

Serum iron levels have been shown to decline both with fever and with strenuous exercise, leading to the supposition that the decrease might be the result of a rise in core body temperature. To evaluate this hypothesis, the serum iron response to an exercise-induced 1.5°C rise in core body temperature was measured. To increase core temperature, five females and two males exercised in an environmental chamber heated to 41°C with a relative humidity of 40%. Blood samples were taken before exercise and immediately after body temperature increased approximately 1.5°C. Blood was also collected 1 h, 6 h, and 24 h postexercise. Results showed that the core body temperature significantly increased (p<0.001) from a mean baseline value of 36.5±0.1°C to 38.1±0.1°C following exercise. A one-way repeated measures analysis of variance was used to examine the effect of increased core body temperature on serum iron levels over the five time periods: preexercise, immediate postexercise, and 1 h, 6 h, and 24 h postexercise. The results indicated that there were no significant differences in serum iron levels among time periods. This suggests that the previously reported depression of serum iron levels that occurs with fever and after prolonged exercise is not the result of hyperthermia. Rather, the change in serum iron occurs in response to biological or physiological stressors, such as bacterial infection, muscle damage, or unusual trauma. Further studies are needed to explicate the mechanisms responsible for these changes.     

Influence of temperature and daylength on population development ofAphis gossypii onCucurbita pepo

The life table parameters ofAphis gossypii Glover were evaluated in tow sets of experiments onCucurbita pepo. The first set was conducted at six constant temperatures (5°C increments from 10–35°C) with 12 h photophase. The second set of experiments was conducted at 6, 12, and 18 h photophase at 25°C. Nymphal survivorship was 100% at 15, 20, 25 and 30°C. However, it was 80 and 0% at 10 and 35°C, respectively. The optimum temperature for body length was 10°C, and body length decreased with increasing temperature.A. gossypii attained its optimum growth and reproduction at 25°C. At this temperature, the net reproductive rate (79.7), intrinsic rate of increase (0.496) and finite rate of increase (1.6) were largest while generation time (6.6 d) and population doubling time (1.4 d) were smallest. Temperatures above and below 25°C reduced the net reproductive rate, and the intrinsic and finite rates of increase. The intrinsic and finite rates of increase ofA. gossypii reared at 18 h photophase (0.53 and 1.7) were significantly higher than at 12 (0.43 and 1.5) and 6 h daylength (0.49 and 1.6).     

Refrigeration of blood samples prior to separation is essential for the accurate determination of plasma or serum zinc concentrations

An evaluation of refrigeration (7°C) to prevent falsely high plasma or serum zinc concentrations owing to elapsed time between blood collection and centrifugation was performed. At room temperature (23°C), both plasma and serum zinc concentrations increased significantly, if blood samples were stored uncentrifuged. Plasma zinc concentrations increased 6.3% at 1 h and 40.7% at 24 h, whereas serum zinc concentrations increased only 0.9% at 1 h and 12.5% at 24 h at room temperature. When blood samples were stored uncentrifuged in the refrigerator for up to 24 h, there were no significant increases in zinc concentrations in either plasma or serum. These findings suggest that plasma or serum separation should be performed immediately after blood drawing to obtain accurate zinc concentrations, and if this is not feasible, the samples should be immediately refrigerated and separation performed within eight hours.     

Polyamine content and chilling susceptibility are affected by seasonal changes in temperature and by conditioning temperature in cold-stored 'Fortune' mandarin fruit

‘Fortune’ mandarins are prone to develop pitting and necrosis upon exposure to low temperatures. We have examined the effect of field temperature during fruit maturation and the effect of conditioning temperatures (from 2 to 37°C) prior to cold storage on the content of polyamines (PAs) and on chilling susceptibility in order to understand the role of PAs in maturation and chilling tolerance of this citrus cultivar. Chilling susceptibility and the content of PAs were more affected by seasonal changes in field temperature than by the stage of fruit maturity. The highest putrescine (Put) and spermidine (Spd) content was found in fruits exposed to the lowest field temperatures. These fruits were in turn more susceptible to develop chilling injury (CI) after storage at 2°C. Spermine (Spm), however, decreased in attached fruit with time of exposure to temperatures below 12°C. Temperature pretreatments for 3 days above 20°C of fruits detached from the tree reduced CI, the more so the higher the conditioning temperature. Put and Spd increased with temperature conditioning in detached fruits, differing from the response of fruits attached to the tree. No direct relationship between induced levels of these PAs and the tolerance to CI was found. Levels of Put and Spd increased at temperatures (22, 30 and 37°C) which increased the tolerance and also at temperatures (6 and 12°C) which accelerated the appearance of chilling symptoms. In contrast, a significant increase in Spm levels was only found after conditioning at 30 or 37°C. After cold storage a general decline in PA levels occurred in all temperature‐conditioned mandarins. In most cases no significant differences among fruit exposed to effective and non‐effective pretreatments were observed. PA content increased again after transferring cold‐stored fruits to 20°C, whereas the CI index was barely affected. In conclusion, PA changes in the flavedo of ‘Fortune’ mandarins appear to be related to variations in temperature rather than to stage of maturity or tolerance to chilling.     

Host and environmental effects on the infection of maize by Puccinia sorghi. II. Post-penetration development

The numbers of pustules which subsequently developed on maize seedlings incubated at 5, 10, 15, and 20 °C and 100% r.h. were directly related to the temperature and length of incubation. The generation time was 16 days at 10 °C, 10 days at 15 °C, 7 days at 20 °C and 5 days at 25 °C. Increase in urediniospore production was observed with increase in temperature. Increase in the inoculum concentration up to 5 × 10⁴ urediniospores/ml increased the number of resultant uredinia. However, further increases did not increase uredinia-formation.     

Subcellular fractionation of postmortem brain

Abstract— Procedures used to separate subcellular organelles from fresh brain were applied to brains which had been removed from guinea pigs (1) immediately after death; (2) after the dead animal was maintained at room temperature for 3 h, followed by 16–17 h at 4°C; or (3) after the dead animal was maintained for 19–20 h at room temperature. Subcellular fractionation of the brains in 0.32 M sucrose was followed by discontinuous density gradient centrifugation of the crude mitochondrial fraction. After overnight storage of brains at room temperature, there was a moderate shift in succinate dehydrogenase activity from sub-fraction C (mitochondria) to subfraction B (synaptosomes). There was little change in the distribution of galactolipid among particulate subfractions. There was little change in distributions of monoamine oxidase or acetylcholinesterase activities. Under the less extreme postmortem conditions, there were no shifts in the subcellular distributions of brain enzymes. Ultrastructural changes were much more profound and consisted of losses of identifiable mitochondria and synaptosomes and a progressive increase in very dense bodies. Our results suggest that in spite of the marked morphological changes, meaningful separation of subcellular organelles can be achieved with postmortem tissue.     

Serum- and albumin-free cryopreservation of endothelial monolayers with a new solution

Cryopreservation is the only long-term storage option for the storage of vessels and vascular constructs. However, endothelial barrier function is almost completely lost after cryopreservation in most established cryopreservation solutions. We here aimed to improve endothelial function after cryopreservation using the 2D-model of porcine aortic endothelial cell monolayers.?The monolayers were cryopreserved in cell culture medium or cold storage solutions based on the 4°C vascular preservation solution TiProtec^®, all supplemented with 10% DMSO, using different temperature gradients. After short-term storage at ?80°C, monolayers were rapidly thawed and re-cultured in cell culture medium.?Thawing after cryopreservation in cell culture medium caused both immediate and delayed cell death, resulting in 11 ± 5% living cells after 24 h of re-culture. After cryopreservation in TiProtec and chloride-poor modifications thereof, the proportion of adherent viable cells was markedly increased compared to cryopreservation in cell culture medium (TiProtec: 38 ± 11%, modified TiProtec solutions ≥ 50%). Using these solutions, cells cryopreserved in a sub-confluent state were able to proliferate during re-culture. Mitochondrial fragmentation was observed in all solutions, but was partially reversible after cryopreservation in TiProtec and almost completely reversible in modified solutions within 3 h of re-culture. The superior protection of TiProtec and its modifications was apparent at all temperature gradients; however, best results were achieved with a cooling rate of ?1°C/min.?In conclusion, the use of TiProtec or modifications thereof as base solution for cryopreservation greatly improved cryopreservation results for endothelial monolayers in terms of survival and of monolayer and mitochondrial integrity.