Priming Duration Research Articles

Effects of different priming treatments and priming durations on germination percentage of parsley (Petroselinum crispum L.) seeds

The effects of different priming treatments and priming durations on germination percentage at different temperatures in parsley seeds were studied. The seeds were treated for 2, 4, 6 and 8 days with the PEG 6000 (–0.5 MPa, –1.0 MPa and –1.5 MPa), KNO3 (0.30 mol/L and 0.35 mol/L), Mannitol (0.50 mol/L and 0.60 mol/L) and hydropriming (12h, 24h, 36h and 48h) and unprimed (control). Germination studies were made at 5, 10, 15, 20 and 25°C. Percentage of germination at different temperatures was significantly affected by priming treatments. Hydropriming (12h, 24h and 36 h) and mannitol 0.60 mol/L at 2 day generally had the highest germination percentages. In general, the highest germination percentage with priming was determined at 10°C. It may be said that seed priming treatments increased seed germination percentage at both low and high temperatures. The highest germination percentages were observed in both hydropriming and mannitol treatments as compared with PEG and KNO3 treatments. The PEG and KNO3 (2 and 4 days) treatments were better than unprimed treatment in all of the temperatures.

Priming 처리시간 및 온도가 목초종자의 발아특성에 미치는 영향

종자의 priming은 종자의 발아율 향상과 유식물의 초기정착에 중요한 기술 중의 하나이다. 본 시험에서는 목초의 주요 초종인 tall fescue, orchardgrass, alfalfa 및 white clover의 발아율 향상과 발아 균일도를 증가시키기 위하여 priming 처리기간과 처리온도에 따라서 목초의 발아율을 조사하였다. 본 시험은 분할구 배치법으로 주구는 priming 처리시간으로 화본과 목초는 2일, 4일, 6일 및 8일을 두었으며, 두과목초는 1일, 2일, 3일 및 4일을 두었다. 세구는 priming 온도로 화본과 두과 목초 모두 10, 15 및 <TEX>$20^{\circ}C$</TEX>를 두었다. Priming후 발아세, 발아율, 평균발아소요일수 및 T50은 초종과 priming 처리기간 및 온도에 따라 다르게 나타났다. Priming 처리기간에서는 화본과 목초인 톨 페스큐와 오차드그라스는 6일에 발아율이 높았으나, 두과목초인 알팔파와 화이트 클로버는 2일에 발아율이 높았다. 한편 priming 처리 온도에서는 오차드그라스는 온도가 낮아짐에 따라 발아율이 증가하였으나, 두과목초인 알팔파와 화이트 클로버는 온도가 <TEX>$10^{\circ}C$</TEX>에서 <TEX>$20^{\circ}C$</TEX>로 증가함에 따라 발아율이 증가하였다. 이상의 결과를 종합해 보면 목초의 priming은 초종에 따라 적정 처리시간 및 온도가 달랐다. Seed priming is an useful technique for increasing germination and early establishment of seedlings. In this experiment, the conditions for priming of pasture seeds (tall fescue, orchardgrass, alfalfa and white clover) have been optimized to ensure an early germination and more uniform growth of seedlings. The experiment was conducted in a split plot design with three replications. The main plots consisted of four different priming duration such as 2, 4, 6 and 8 days for grass, and 1, 2, 3 and 4 days for legume. The subplots were consisted of three priming temperature such as 10, 15 and <TEX>$20^{\circ}C$</TEX>. Effects of priming duration and temperature were different in all four pasture seeds examined. The germination of primed grass (tall fescue and orchardgrass) was the highest on 6 days in priming duration, whereas that of legume (alfalfa and white clover) was the highest on 2 days. In priming temperature, the germination of primed orchradgrass increased as decreasing temperature, however that of legume increased as increasing temperature. These results suggest that seed priming induced earlier and higher germination for all four pastures tested. However, the degree of priming effectiveness on pasture species depending on the priming duration and its temperature.

Effect of Potassium Nitrate Priming on Seed Germination of Seashore Paspalum

Germination of seashore paspalum (Paspalum vaginatum Swartz) is a critical factor influencing seedling establishment when seeded directly in fields. In this research, pregermination priming with osmotic solution was used to improve the germination percentage of seashore paspalum. The goal of this study was to develop techniques that improve the germination of a seashore paspalum cultivar (SeaSpray). Seeds were subjected to priming in petri dishes with solutions of KNO3 at 25 °C for 24, 48, and 72 h in growth chambers. Germination percentage differed by priming duration as well as concentration of priming media. Based on the germination percentage 14 days after imbibition, the most promising priming condition was the treatment with 0.2% or 0.5% KNO3 for 72 h at a constant temperature of 30 °C and 0.2% or 0.5% KNO3 for 48 to 72 h at alternating temperature of 25/35 °C. Both concentrations showed reasonable germination percentage greater than 85% at alternating temperature condition. Priming with KNO3 solution for 48 to 72 h improved not only germination percentage, but also uniformity. The increased duration of priming with KNO3 was positively correlated with an improved germination percentage. The effect of increasing concentration was the most apparent at a constant temperature (30 °C) regime with the treatment of 0.2% KNO3 priming. Germination percentage was increased from 34.3% to 68.0% 2 weeks after imbibition (WAI) as the priming duration was increased from 24 to 72 h. Priming with KNO3 for 3 days also had a modest effect on germination percentage (greater than 74.7%) at 1 WAI. Therefore, priming with 0.2% or 0.5% solution of KNO3 for 72 h is a recommended method that can be practically applied for increasing germination of paspalum under an alternating temperature (25/35 °C) condition. The regression analysis between odds of germination percentage and germination time showed that priming treatment increased internal activities during the second stage of seed germination.

Developmental reprogramming of rat GLUT5 requires glucocorticoid receptor translocation to the nucleus

Fructose consumption has increased dramatically but little is known about mechanisms regulating the intestinal fructose transporter GLUT5 in vivo. In neonatal rats, GLUT5 can be induced only by luminal fructose and only after 14 days of age, unless the gut is primed with dexamethasone prior to fructose perfusion. To elucidate the mechanisms underlying dexamethasone modulation of GLUT5 development, we first identified the receptor mediating its effects then determined whether those effects were genomic. The glucocorticoid receptor (GR) antagonist RU486 dose-dependently prevented the dexamethasone-mediated effects on body weight, intestinal arginase2 (a known GR-regulated gene) and GLUT5. In contrast, an antagonist of the mineralocorticoid receptor as well as agonists of progesterone (PR) and pregnane-X (PXR) receptors did not block the effects of dexamethasone. These receptor antagonists and agonists had no effect on the intestinal glucose transporter SGLT1. Translocation of the GR into the enterocyte nucleus occurred only in dexamethasone-injected pups perfused with fructose, was accompanied by marked increases in brush border GLUT5 abundance, and was blocked by RU486. A priming duration of approximately 24 h is optimal for induction but actinomycin D injection before dexamethasone priming prevented dexamethasone from allowing luminal fructose to induce GLUT5. Actinomycin D had no effect on dexamethasone-independent fructose-induced increases in glucose-6-phosphatase mRNA abundance, suggesting that it did not prevent fructose-induction of GLUT5, but instead prevented dexamethasone-induced synthesis of an intermediate required by fructose for GLUT5 regulation. In suckling rats < 14 days old, developmental regulation of transporters may involve cross-talk between hormonal signals modulating intestinal maturation and nutrient signals regulating specific transporters.

Priming Duration Influences Anatomy and Germination Responses of Parsley Mericarps

Germination studies indicated that increasing priming duration (-1.0 MPa at 20 °C for 7, 14, or 21 days) increased `Moss Curled' parsley [Petroselinum crispum (Mill.) Nyman ex A.W. Hill] germination rate quadratically and seed moisture content linearly. A histological and anatomical study was conducted to identify and/or quantify principle mericarp organ or tissue volume changes influenced by priming duration. Embryo volume increased as priming duration increased from 7 to 21 days (0.014 to 0.034 mm3), and this was due more to radicle (0.007 to 0.022 mm3) than to cotyledon (0.006 to 0.011 mm3) growth. Concomitant with increased embryo volume was increased volume of the depleted layer (space formation, surrounding the embryo), from 0.038 after 7 days to 0.071 mm3 after 21 days, and increased hydrolysis of central endosperm (a thick-walled endosperm type). In nonprimed mericarps, central endosperm cells constituted 97% of the endosperm volume. The remaining 3% was comprised of 1% depleted layer and 2% distal endosperm (small, thin-walled, and irregularly shaped endosperm cells). During 7 or 21 days of priming, ≈10% or 40%, respectively, of central endosperm cells were hydrolyzed centrifugally around the embryo with a corresponding decrease in volume of central endosperm with thick cell walls. In addition, distal endosperm cells adjacent to the depleted layer, containing reserve materials, were digested of contents following 21 days priming, and sometimes, following 7 days priming. A long priming duration resulted in degradation of pericarp tissues, as indicated visually and by a decline in pericarp volume. We hypothesize that priming duration of parsley primarily influences radicle growth and centrifugal digestion and utilization of central and distal endosperm, resulting in a larger depleted layer required for embryo volume increases. Secondary events influenced by priming duration include cotyledon growth and degradation of pericarp tissues.

Effects of priming duration on retention over the first 1½ years of life

Exposing individuals to an isolated component (a prime) of a prior event alleviates its forgetting. Two experiments with 120 human infants between 3 and 18 months of age determined the minimum duration of a prime that can reactivate a forgotten memory and how long the reactivated memory persists. Infants learned an operant task, forgot it, were exposed to the prime, and later were tested for renewed retention. In Experiment 1, the minimum duration of an effective prime decreased logarithmically with age, but was always longer than the duration of a mere glance. In Experiment 2, the reactivated memory was forgotten twice as fast after a minimum-duration prime as after a full-length one, irrespective of priming delay and infant age. These data reveal that the minimum effective prime duration psychophysically equates the accessibility of forgotten memories. We conclude that priming is perceptually based with effects that are organized on a ratio (log) scale.

Seed Priming Effect on Symbiotic Germination and Seedling Development of Orchis palustris Jacq.

Seeds of Orchis palustris Jacq. were primed for 1- to 5-day in polyethylene glycol (PEG-6000) solutions at -0.5, -1.0 or -1.5 MPa. The seeds were symbiotically germinated with BNR 8-3 mycorrhizal fungus on oatmeal agar at 22 °C. In general, priming hastened rapid germination. At -1.5 MPa water potential, the first to germinate was eight days compared to 18 days for the control. Percentage germination increased as priming water potential decreased, and the percentage germination was 55%, 58%, and 65%, at -0.5, -1.0, and -1.5 MPa, respectively, versus 43% for the nonprimed control. Priming duration from 1 to 5 days had little effect on germination performance. The best germination percentage (68%) was obtained from 1 day at -1.5 MPa treatment.

Seed Priming Winter Wheat for Germination, Emergence, and Yield

Insufficient stand establishment of winter wheat (Triticum aestivum L.) is a major problem in the low‐precipitation (&lt;300 mm annual) dryland summer fallow region of the inland Pacific Northwest, USA. Low seed zone water potential, deep planting depths with 15 cm or more soil covering the seed, and soil crusting caused by rain before seedling emergence frequently impede winter wheat stands. A 2‐yr study involving laboratory, greenhouse, and field components was conducted to determine seed priming effects on winter wheat germination, emergence, and grain yield. Two cultivars were used because of their strong (Edwin) and moderate (Madsen) emergence capabilities. Germination rate was measured in the laboratory by 44 treatment combinations (two cultivars × three priming durations × seven priming media + two checks). Germination rate differed between cultivars as well as by priming duration, priming media, and concentration of priming media. The most promising laboratory treatments were advanced to greenhouse and field experiments where emergence and grain yield (field only) were measured in 10 treatments (two cultivars × four priming media + two checks) from wheat planted deep with 16 cm of soil covering the seed. In the greenhouse, seed primed in potassium chloride (KCl), polyethylene glycol (PEG), and water led to enhanced emergence of Madsen, but not of Edwin, compared with checks. Rate and extent of seedling emergence was greater for Edwin compared with Madsen irrespective of priming media in three of four field plantings at Lind, WA. None of the seed priming media benefited field emergence or subsequent grain yield in either cultivar compared with checks. Overall, results suggest that seed priming has limited practical worth for enhancing emergence and yield of winter wheat planted deep into summer fallow.

Short term primings with different progestogen intravaginal devices (MAP, FGA and CIDR) for eCG-estrous induction in anestrus ewes

Two experiments with 260 ewes compared the effectiveness of different progestogens and the amount of medroxyprogesterone acetate (MAP) contained in the intravaginal devices with short term primings for equine chorionic gonadotrophin (eCG) estrous induction in anestrus ewes. In the first experiment, 147 Polwarth and Polwarth x Ile de France ewes were allocated to three groups, treated with MAP sponges (MAP group; n=51), fluorogestone sponges (FGA group; n=47) or devices containing progesterone (CIDR group; n=49) for 6 days. At withdrawal of intravaginal devices all animals received 380 IU eCG and were grouped with rams. Ewes in estrus were identified twice daily during a 72 h observation period. Four weeks after estrus, pregnancy was determined by transrectal ultrasonography. There was no significant differences among treatments for ewes in estrus (MAP: 94.1%, FGA: 91.5%, CIDR: 95.9%) or in conception rates (MAP: 62.5%, FGA: 67.4%, CIDR: 59.6%). In the second experiment, 113 Romney Marsh ewes were allocated to four groups in a 2×2 factorial design, based on the dosage of MAP (30 or 60 mg) and priming duration for 14 or 6 days (groups 14D30, n=27; 6D30, n=29; 14D60, n=29; 6D60 n=28). At sponge withdrawal, all ewes received 350 IU eCG and were placed with rams. Ewes that exhibited estrus and pregnancy were recorded. There were no differences in response to estrus (86.2, 82.1, 100 and 89.7%) and conception rates (44.0, 43.5, 44.4 and 34.6%, respectively, for 6D30, 6D60, 14D30 and 14D60). It was concluded that CIDR, FGA or MAP sponges were equally effective with 6 days primings for estrous induction in anestrus ewes. However, 30 mg MAP sponges are as effective as those commercially available.

Solid Matrix Priming Hastens Canterbury Bells Seed Germination

Canterbury bells (Campanula medium `Champion Blue') seeds were primed using calcined clay at 68 °F (20 °C) for 1, 3, or 5 days at water potentials (Ψ) of -25, -20, -18, or -16 bars (-2.5, -2.0, -1.8, or -1.6 MPa). Germination was fastest (3.0 to 3.1 days) after priming with a Ψ of -18 or -16 bars for 5 days. Seeds primed for 3 or 5 days with moisture present germinated faster than nonprimed seeds, but time to 50% germination (T50) was longer when seeds were primed for 1 day regardless of Ψ compared to nonprimed seed. Germination uniformity decreased (time from 10% to 90% germination, T10-90, increased) as Ψ increased. Although a curvilinear relationship existed between T10-90 and priming duration, T10-90 did not differ between nonprimed seeds and seeds in any priming treatment except those primed for 3 days with 20% moisture (-16 bars). Priming did not affect total germination percentage (97%).

A hierarchical dynamical map as a basic frame for cortical mapping and its application to priming.

A hierarchical dynamical map is proposed as the basic framework for sensory cortical mapping. To show how the hierarchical dynamical map works in cognitive processes, we applied it to a typical cognitive task known as priming, in which cognitive performance is facilitated as a consequence of prior experience. Prior to the priming task, the network memorizes a sensory scene containing multiple objects presented simultaneously using a hierarchical dynamical map. Each object is composed of different sensory features. The hierarchical dynamical map presented here is formed by random itinerancy among limit-cycle attractors into which these objects are encoded. Each limit-cycle attractor contains multiple point attractors into which elemental features belonging to the same object are encoded. When a feature stimulus is presented as a priming cue, the network state is changed from the itinerant state to a limit-cycle attractor relevant to the priming cue. After a short priming period, the network state reverts to the itinerant state. Under application of the test cue, consisting of some feature belonging to the object relevant to the priming cue and fragments of features belonging to others, the network state is changed to a limit-cycle attractor and finally to a point attractor relevant to the target feature. This process is considered as the identification of the target. The model consistently reproduces various observed results for priming processes such as the difference in identification time between cross-modality and within-modality priming tasks, the effect of interval between priming cue and test cue on identification time, the effect of priming duration on the time, and the effect of repetition of the same priming task on neural activity.

Viability and Vigor of Osmotically Primed Muskmelon Seeds After Nine Years of Storage

The viability and vigor of osmotically primed (0.3 m KNO3, 6 days, 25C) and nonprimed `PMR 45' muskmelon (Cucumis melo L.) seeds were compared after storage for 9 years at &lt;20C and 6% moisture content (MC, dry weight basis). Viability was compared at 20, 25, and 30C at water potentials of 0, -0.2, -0.4, -0.6, and -0.8 MPa and in soil. Additionally, stored primed and nonprimed seeds were either primed, aged (15% MC and 45C) for up to 8 days, or aged for 72 hours and primed. The force required to puncture 5-mm-long, micropylar seed pieces was measured using an Instron universal testing machine. Less force was required to puncture primed seed pieces at 0, 5, 15, 20, and 25 hours of imbibition, demonstrating that osmotic priming weakens the perisperm envelope tissue that the radicle must penetrate for germination to occur. In an earlier report, germination rate and final germination percentages were higher for osmotically primed seeds both in laboratory tests and field emergence studies conducted immediately after priming. After 9 years in storage, nonprimed seeds germinated to higher percentages in water at 30C and reduced water potential at all temperatures, while primed seeds germinated to higher percentages in water at 20 and 25C and exhibited a higher percentage of seedling emergence at a soil MC of 17%. Priming durations of ≤5 days had no effect on the viability, while longer durations decreased the viability of stored primed and nonprimed seeds. Priming generally decreased the log mean time to germination of stored nonprimed seeds but increased values for stored primed seeds. Controlled deterioration increased the log mean time to germination and decreased the viability of primed seeds faster than nonprimed seeds. Priming following controlled deterioration had no effect on nonprimed seeds and reduced the percent viability of primed seeds by 20%. Osmotic priming has a deleterious effect on the seed storage life of muskmelon seeds.

Induction of meiotic maturation in vivo in the mouse by IMP dehydrogenase inhibitors: effects on the developmental capacity of ova.

The present study was conducted to examine the effects of priming duration and inosine monophosphate (IMP) dehydrogenase inhibitors on the fertilization and pre- and postimplantation development of ova from immature mice. Mice were primed with equine chorionic gonadotropin (eCG) and 1 d later were treated with mycophenolic acid (MA) or mizoribine (Mz; also known as bredinin) or an equal volume of the vehicle. Two days after priming, mice received human chorionic gonadotropin (hCG) and were mated with fertile males. Some mice received hormone but were not mated. Ova were isolated from the oviducts 23-24 hr post-hCG and cultured in Whitten's medium. Some mice were not killed until 7 or 19 d postvaginal plug to determine the extent of implantation or development to term, respectively. In superovulated control mice, 94% of ova developed to two-cells and 82% of these progressed to the blastocyst stage. Nineteen of 23 mice (83%) had implantations (24/mouse) and 20 of 24 mice (83%) had term embryos (11/mouse). Induction of meiotic maturation with Mz or MA after 1 d of priming, followed 1 d later by hCG injection and mating, resulted in a significant loss of preimplantation developmental capacity (20-22% two-cells; 29-50% blastocysts). These numbers were similar whether or not the mice were mated, indicating that the development was parthenogenetic. In addition, Mz treatment reduced the number of mice with implantation sites (13 of 19, 68%), the number of implantations per mouse (10), the viability of the implantations, and development to term (four of 24, mice, 17%; one embryo/mouse). Thus, most of the implanted embryos were resorbed after implantation. This effect could be attributed, in part, to each of the following: (1) parthenogenetic activation; (2) aging of the metaphase II oocyte before insemination; and (3) resumption of meiotic maturation before the oocyte had reached its full developmental potential. Coincident gonadotropin injection reversed the loss of development brought about by IMP dehydrogenase inhibitors. These data show that induction of premature meiotic maturation by IMP dehydrogenase inhibitors results in a significant loss of developmental capacity and indicates that active purine metabolic pathways in situ maintain meiotic arrest and prevent premature meiotic maturation that would result in compromised development.

数種野菜種子のプライミングにおける塩類溶液の影響

For priming of carrot seeds, KNO3, K3PO4, MgCl2•6H2O, NaCl and NaNO3 were similarly effective at -10 bars. No germination during priming treatment was found with K3PO4. The effect of K3PO4 for priming did not decrease very much as the duration of treatment was prolonged. Its effect was considered to be attributable to tertiary phosphate ions, because a similar result was obtained for Na3PO4•12H2O. Osmotic potentials of K3PO4 solutions which showed higher effects on priming were constantly -7.5 bars, while those of NaCl changed from -7.5 to -12.5 bars depending on treatment temperature and duration.Germination during priming treatment for eggplants, mitsubas (Cryptotaenia japonica Hassk.), Welsh onions, spinaches and edible burdocks was suppressed clearly more with K3PO4 than with NaCl. For eggplants and edible burdocks, osmotic potentials of K3PO4 solution which showed higher effects on priming were stable even if priming duration was varied. It was noted for mitsubas, Welsh onions and edible burdocks that the priming duration required for higher effects of K3PO4 solution showed a comparatively wide range.The effect of tertiary phosphates shown in our experiments may be due to high pHs of their solutions. Tertiary phosphates may be potentially useful and convenient osmotica for priming of seeds of many species.

Maturational state of the auditory receptor system and the sensitive period for priming for audiogenic seizure in mice

The effect of priming duration and tympanic membrane perforation on development of seizure susceptibility were studied in 13- and 26-day-old C57BL 6J mice. The results show that longer durations of exposure (90 or 120 s) are more effective for induction of seizure susceptibility in the younger mice whereas short durations of exposure (10 or 20 s) are more effective for the older mice. Tympanic membrane perforation was effective in both young and old mice, although the older mice tended to show few clonic seizures. The results are interpreted as indicating that developmental changes in cochlear vulnerability to noise-induced damage are important determinants of the observed “sensitive” period for priming in these mice.

CIRCULATORY DYNAMICS OF CARDIOPULMONARY BYPASS

P HYSIOLOGIC and metabolic changes of varying complexity accompany the use of the heart-lung machine in man. These changes relate to many factors, such as the design of the apparatus, the ventilating gas, the pH of the priming blood, the rate and duration of perfusion, the body temperature and the need for and manner of producing cardiac arrest. Many of the changes in acid-base balance, blood volume and myocardial function are difficult or impossible to duplicate in the laboratory. For these reasons this study presents circulatory and respiratory data obtained during cardiopulmonary bypass in 50 adults undergoing operation for a variety of congenital and acquired diseases of the heart. It attempts to integrate the hemodynamic responses, to indicate some unusual responses, and to present technics that have been found helpful in avoiding serious abnormalities.