Effect of temperature and duration of storage on quality of stored sweetpotatoes

For the six varieties studied, storage temperatures in the narrow ran?e of 55 to 60° F. were found to be most suitable.     

Effects of growth retardants on bulbil production by Narcissus twin-scales

Narcissus twin-scale propagules, cut from various positions in the parent bulb, were incubated with gibberellic acid (GA₃) or growth retardants. Bulbil production was inhibited in all cases by GA₃ at 10–100 mg/litre. Chlormequat chloride, chlorphonium chloride and paclobutrazol also inhibited bulbil production; in the case of paclobutrazol, outer twin-scales were more sensitive to lower concentrations of the retardant than inner ones. Ancymidol enhanced bulbil production (in numbers by up to 15%) in the outermost twin-scales, and had no stimulatory effect on the inner twin-scales. Treatments affected bulbil numbers and bulbil lengths about equally.     

Effect of storage duration, storage temperature, and diluent on the viability and fertility of fresh ram sperm

Cervical artificial insemination (AI) in sheep with fresh semen yields a much higher pregnancy rate than when frozen-thawed semen is used, and consequently frozen semen is only acceptable for laparoscopic insemination. The short life span of fresh semen is a major constraint on the use of AI in genetic improvement programs for sheep. The main objective of this study was to examine the effects of storage conditions on viability and fertilization ability of fresh ram (Ovis aries) semen up to 72 h postcollection. Experiment 1 was designed to evaluate the effect of diluent type (standard skim milk, AndroMed, OviPro, and INRA 96) and storage temperature (5 °C and 15 °C) on the motility and viability of fresh ram semen. Storage temperature, irrespective of diluent, had a significant effect on both motility and viability. Storage at 5 °C maintained acceptable motility and viability up to 72 h compared with that of storage at 15 °C. In Experiment 2, the penetrating ability of fresh ram semen, diluted in either skim milk, AndroMed, or INRA 96, was assessed using artificial mucus. Flat capillary tubes containing artificial mucus were suspended in 250 μL semen at a sperm concentration of 20 × 10⁶/mL. Semen was stored at 5 °C and tested after 6, 24, 48, and 72 h. There was a significant diluent by time interaction. In Experiment 3, the fertilizing ability of fresh ram semen stored at 5 °C was evaluated in vitro. Fresh semen (diluted in either skim milk, AndroMed, or INRA 96) was added to matured ewe oocytes at 6, 24, or 72 h after semen collection. Cleavage rate was recorded at 48 h postinsemination, and blastocyst development was recorded on Days 6 to 9. There was a significant treatment effect on cleavage and blastocyst rates; insemination of semen stored for 24 h resulted in higher rates than those for storage at 72 h. In Experiment 4, the fertilizing ability of fresh ram semen was evaluated in vivo. Semen was diluted in INRA 96, stored at 5 °C, and used to inseminate ewes on the day of collection or at 24, 48, and 72 h postcollection. Multiparous ewes were cervically inseminated at a synchronized estrus. Fertility rate decreased linearly (P < 0.001) up to 72 h after semen collection.     

Promotion by Jasmonic acid of bulb formation in shoot cultures of Narcissus triandrus L.

The in vitro bulb formation by shoot clumpcultures of N. triandrus on media with jasmonicacid (JA) alone or in association with both2-isopentenyladenine (2-iP) or naphthalene acetic acid(NAA) and on medium with only NAA was studied. Themedia with JA plus 2-iP or JA plus NAA caused a highmultiplication of leaves, significantly higher on thatwith 2-iP. Leaf proliferation was low on medium withJA alone. The media containing JA promoted theformation of a bulb at the base of the leaves and thebulbs attained different sizes. On the medium with JAplus NAA, the number of bulbs that reached up to 5 mmin diameter was higher than that on the medium with JAplus 2-iP, but the highest number was formed on themedium with JA alone. The medium with NAA alone led tothe formation of few small bulbs that were elongatedinstead of roundish as those formed on media with JA.Further culture of the bulbs on a growth mediumsuitable to their enlargement increased their size butthe dimensions attained were dependent upon the mediuminitially used for bulb formation. Bulbs derived frommedium with JA alone attained the largest diameter.Almost all the bulbs grown on the growth medium wererooted. Data described here show that JA promotes in vitro bulb formation in shoot cultures of N.triandrus and suggests that JA might play animportant role in the formation and enlargement ofbulbs in Narcissus plants.     

The effect of temperature on the growth and hydrogen production by Citrobacter intermedius

Summary Citrobacter intermedius was grown batchwise in a mineral salts medium with glucose as a carbon and energy source under anaerobic conditions and at different temperatures. The effect of temperature on the following parameters was studied: maximum specific growth rate, max, maximum rate of hydrogen gas production and maximum rate of total gas (H₂ + CO₂) production. Arrhenius plots were used to determine the activation energies associated with max and maximum rates of hydrogen gas production.     

兰州百合鳞茎发育及低温解除休眠过程中内源激素的变化

以兰州百合为试材,研究了鳞茎发育过程中以及2、6、10℃条件下保湿贮藏101 d内母鳞茎与新鳞茎中内源激素的变化。结果表明：鳞茎发育过程中内源ABA含量以及母鳞茎的GA₃与ZR含量增加,而内源IAA含量以及新鳞茎的GA₃与ZR含量下降。低温贮藏期间,母鳞茎与新鳞茎的GA₃、IAA含量均有升高过程,而ABA含量呈下降趋势;新鳞茎的ZR含量呈下降趋势,母鳞茎的ZR含量也有升高过程。低温处理初期的34 d内,内源激素变化最为显著。不同贮藏温度相比较,ABA含量差异不大,GA₃含量随温度升高而下降。在富含淀粉的新鳞茎中,GA₃和ABA表现出极显著的负相关关系,而在淀粉含量较低的母鳞茎中GA₃和ABA无相关性。通径分析结果表明,母鳞茎与新鳞茎的物质代谢机制不同,母鳞茎的物质变化受内源GA₃的调控,新鳞茎主要是ABA作用的结果。     

Comparative studies on the relationship between temperature and duration of embryonic development of rotifers

The embryonic development times of four planktonic rotifers from Neusiedlersee (Austria) (Rhinoglena fertöensis, Brachionus calyciflorus, Keratella quadrata and Polyarthra dolichoptera) were determined at constant temperatures ranging from 0.6 °C to 10.5 °C. Development times decreased with increasing temperatures. The curvilinear relationship between temperature and development time was described by Bělehrádek's equation. Data on embryonic development times of rotifers are summarized and regression equations for the temperature-duration of development relationship are presented. Adaptation to temperature is discussed in the context of the thermal history of the various species and populations.     

The effect of pH and temperature on haemolysin production by Listeria species

Acetoin reductase (EC 1.1.1.4) from Kluyveromyces marxianus var. marxianus NRRL Y-1196 was found to possess the highest specific activity (3.64 units/mg protein) of the four cultures studied. The enzyme was NADH-dependent and catalysed the conversion of acetoin to 2,3-butanediol. It was stable at 40°C for 30 min, but lost 50% cf its activity after 15 min at 50°C. The optimum pH for the enzymatic reduction of acetoin was 7.0. The K _m values of the crude enzyme for acetoin and NADH were determined to be 0.57 mmol/l and 0.045 mmol/l, respectively.     

Effect of storage temperature and duration on viability of eggs of Helicoverpa armigera (Lepidoptera: Noctuidae)

The ability to store different insect stadia for prolonged periods provides considerable flexibility and ability to conduct experiments properly. Therefore, studies were undertaken to determine the effect of storage temperature and duration on viability of eggs of Helicoverpa armigera (Hübner). The percentage egg hatch and incubation period were significantly (P=0.01) influenced by egg age, storage temperature, and storage duration. Egg hatch ranged from 0.0 to 96.8% across temperatures and storage durations. None of the eggs hatched when stored at -20 and 0 degrees C. The regression model with the optimum Mallow Cp statistic for any of the identified linear and quadratic terms did not improve the precision of prediction in egg hatch beyond 67.0%. Forecasting of incubation period based on egg age, storage duration, and durationxtemperature was quite effective (R2=84.2%). Day degrees required for egg hatching decreased with an increase in temperature from 10 to 27 degrees C, and egg age from 0 to 3 days. The day degree requirements were highest for 0-day-old eggs at 10 degrees C, and lowest at 27 degrees C. Although the incubation period was higher, the hatchability was lower for 0- and 1-day-old eggs stored at constant 10 degrees C, these eggs can be stored for 10 days at 10 degrees C, with a hatchability of >75.0%. It was safer to store the H. armigera eggs for 10 days at 10 degrees C, which will hatch within 1.6 to 2.0 days after restoration at 27 degrees C with a hatchability of >75.0%. This information will be useful in planning and execution of experiments involving H. armigera on various aspects of research in entomology.     

Variation in moisture duration as a driver of coexistence by the storage effect in desert annual plants

Temporal environmental variation is a leading hypothesis for the coexistence of desert annual plants. Environmental variation is hypothesized to cause species-specific patterns of variation in germination, which then generates the storage effect coexistence mechanism. However, it has never been shown how sufficient species differences in germination patterns for multispecies coexistence can arise from a shared fluctuating environment. Here we show that nonlinear germination responses to a single fluctuating physical environmental factor can lead to sufficient differences between species in germination pattern for the storage effect to yield coexistence of multiple species. We derive these nonlinear germination responses from experimental data on the effects of varying soil moisture duration. Although these nonlinearities lead to strong species asymmetries in germination patterns, the relative nonlinearity coexistence mechanism is minor compared with the storage effect. However, these asymmetries mean that the storage effect can be negative for some species, which then only persist in the face of interspecific competition through average fitness advantages. This work shows how a low dimensional physical environment can nevertheless stabilize multispecies coexistence when the species have different nonlinear responses to common conditions, as supported by our experimental data.     

The effect of temperature on the kinetics of ethanol production by Saccharomyces uvarum

Summary In view of the interest in high productivity fermentations at increased temperatures, the effect of temperature on the kinetics of ethanol production by Saccharomyces uvarum was investigated in the range 25–43°C. Using a mathematical model and a nonlinear computer simulation package, the kinetic parameters at each temperature were estimated. It was found that the optimal temperature for growth was 34°C, while the specific ethanol production rate was maximal at 37–43°C. Up to 37°C, the inhibitory effects of ethanol on growth and specific ethanol production rate were unaffected by temperature. However, above this temperature, ethanol inhibition increased significantly.     

Effects of soil moisture and temperature on preharvest invasion of peanuts by the Aspergillus flavus group and subsequent aflatoxin development

Four soil temperature and moisture treatment regimens were imposed on Florunner peanuts 94 days after planting in experimental plots in 1980. At harvest (145 days after planting), the incidence of the Aspergillus flavus group and the aflatoxin concentration were greatest in damaged kernels. Extensive colonization of sound mature kernels (SMK) by the A. flavus group occurred with the drought stress treatment (56% kernels colonized); colonization was less in the irrigated plot (7%) and the drought stress plot with cooled soil (11%) and was intermediate in the irrigated plot with heated soil (26%). Aflatoxin was virtually absent from SMK with the last three treatments, but it was found at an average concentration of 244 ppb (ng/g) in drought-stressed SMK. Colonization of SMK by the A. flavus group and aflatoxin production were greater with hot dry conditions. Neither elevated temperature alone nor drought stress alone caused aflatoxin contamination in SMK. When the ratio of SMK colonized by A. flavus compared with A. niger was greater than 19:1, there was aflatoxin contamination, but there was none if this ratio was less than 9:1. Irrigation caused a higher incidence of A. niger than drought did. This may have prevented the aflatoxin contamination of undamaged peanuts.     

Rosmarinic acid production by Lavandula vera MM cell suspension: the effect of temperature

Lavandula vera MM cell suspension, grown at 28 degrees C in a 3-l bioreactor, produced rosmarinic acid maximally at 3 g l(-1)) though most biomass (33.2 g dry wt l(-1)) was at 30 degrees C.     

The effect of temperature and anoxia of rat-kidney slices on their subsequent respiration

1. Rat-kidney slices were kept, aerobically and anaerobically, at 4 degrees , 20 degrees and 38 degrees , for 0.5-24hr. The oxygen consumption was then measured at 38 degrees . 2. After 6hr. of storage at 4 degrees the rate of oxygen consumption was the same as controls, but after 12 and 24hr. of storage the oxygen consumption fell by 22 and 32% respectively; there was no difference between the slices kept aerobically and anaerobically for periods of 2-24hr. at 4 degrees . 3. Anaerobic storage at 20 degrees for 2hr. did not affect the subsequent rate of oxygen consumption, but after 4 and 6hr. the anaerobically stored tissue showed loss of oxygen consumption. Aerobic storage had no effect for 6hr. 4. There was a marked fall in the capacity to consume oxygen after 0.5hr. at 38 degrees without oxygen. 5. Kidney slices stored at 4 degrees lost nitrogen. The presence of oxygen did not affect this nitrogen loss.     

The effect of temperature and anoxia of kidney on the subsequent oxidative phosphorylation of mitochondria

1. Kidneys were kept anoxic at 4 degrees , 20 degrees and 38 degrees . Mitochondria were then isolated and their oxidative phosphorylation and respiration were determined. 2. Under all conditions the rate of phosphate esterification was affected to a greater extent, or earlier, than oxygen consumption. 3. Glutamate and succinate were used as substrates. The depression of P/O ratio was greater for glutamate at 4 degrees , and for succinate at 20 degrees . 4. Anoxia abolished the inhibiting effect of fluoride on respiration. 5. Phosphate esterification, after anoxia, was higher in the presence of fluoride than its absence, whereas in control preparations they were the same. 6. The decrease in P/O ratio did not appear to be due to activation of adenosine triphosphatase, as activities of both Mg(2+)-and dinitrophenol-activated adenosine triphosphatases were decreased after anoxia.     

Prior frozen storage enhances the effect of edible coatings against Listeria monocytogenes on cold-smoked salmon during subsequent refrigerated storage

Aims: Listeria monocytogenes is a major safety concern for ready‐to‐eat foods. The overall objective of this study was to investigate whether prior frozen storage could enhance the efficacy of edible coatings against L. monocytogenes on cold‐smoked salmon during subsequent refrigerated storage. Methods and Results: A formulation consisting of sodium lactate (SL, 1·2–2·4%) and sodium diacetate (SD, 0·125–0·25%) or 2·5% Opti.Form (a commercial formulation of SL and SD) was incorporated into each of five edible coatings: alginate, κ‐carrageenan, pectin, gelatin and starch. The coatings were applied onto the surface of cold‐smoked salmon slices inoculated with L. monocytogenes at a level of 500 CFU cm^?2. In the first phase, the slices were first frozen at ?18°C for 6 days and stored at 22°C for 6 days. Alginate, gelatin and starch appeared to be the most effective carriers. In the second phase, cold‐smoked salmon slices were inoculated with L. monocytogenes, coated with alginate, gelatin or starch with or without the antimicrobials and stored frozen at ?18°C for 12 months. Every 2 months, samples were removed from the freezer and kept at 4°C for 30 days. Prior frozen storage at ?18°C substantially enhanced the antilisterial efficacy of the edible coatings with or without antimicrobials during the subsequent refrigerated storage. Conclusions: Plain coatings with ≥2 months frozen storage and antimicrobial edible coatings represent an effective intervention to inhibit the growth of L. monocytogenes on cold‐smoked salmon. Significance and Impact of the Study: This study demonstrates the effectiveness of the conjunct application of frozen storage and edible coatings to control the growth of L. monocytogenes to enhance the microbiological safety of cold‐smoked salmon.     

百合鳞茎发育过程中碳水化合物含量及淀粉酶活性变化

以兰州百合和亚洲系"精粹"百合为试材,探讨了鳞茎发育过程中不同部位淀粉、可溶性糖含量和淀粉酶活性的变化。结果表明,母鳞茎作为百合萌发阶段的代谢源,其外部鳞片是代谢更为活跃的部位。淀粉和可溶性糖含量同时增加是百合新鳞茎开始膨大的标志。蔗糖是百合鳞茎中可溶性糖的主要形态,还原糖的变化体现了碳水化合物的供应及转化。淀粉酶在百合鳞茎发育过程中对调节和平衡碳水化合物的形态起重要作用。