Leaf anatomy and water loss of in vitro PEG-treated ‘Valiant’ grape

Polyethylene glycol was used to induce water stress of micropropagated Valiant grape. Reduced growth and slow rooting were observed in treated plantlets with 2, 4 and 6% polyethylene glycol as compared to control plantlets with no polyethylene glycol in the rooting medium. At high concentrations of 4 and 6%, leaves exhibited wilting and necrosis. At the 2% level, plantlets recovered and grew satisfactorily. Detached leaves of treated plantlets with 2% polyethylene glycol lost less water than controls when exposed to low humidity for 4 hours. Leaf anatomy of plantlets treated with 2% polyethylene glycol, control (in vitro plantlets) and greenhouse-grown plants were compared under light microscopy. Leaves from control plantlets contained larger mesophyll cells, lacked normal palisade layer formation, had greater intercellular pore spaces and fewer chloroplasts. Leaves from polyethylene glycol-treated plantlets, however, had smaller mesophyll cells, a more defined palisade layer, reduced intercellular pore space and the greatest number of chloroplasts. These results suggest that an osmoticum such as polyethylene glycol may be used to induce more normal leaf anatomy and reduced water loss in micropropagated Valiant grapes.Abbreviations BA 6-benzylaminopurine - FAA formalin-acetol-alcohol - MS Murashige & Skoog (1962) medium - MW molecular weight - NAA napthaleneacetic acid - PEG polyethylene glycol - TBA tertiary butyl alcohol     

The water-soluble fullerene derivative "Radical Sponge" exerts cytoprotective action against UVA irradiation but not visible-light-catalyzed cytotoxicity in human skin keratinocytes

Fullerene was entrapped in polyvinylpyrrolidone of 60-80 kDa at a molar ratio range of 0.42-0.67:1, resulting in a water-soluble derivative with a mean particle diameter of about 688 nm, named "Radical Sponge" because of its ROS-scavenging ability as previously demonstrated, and examined in the present study for its photo-biological actions toward human skin keratinocytes HaCaT. The keratinocytes were repeatedly irradiated with a visible light of wavelengths of 400-2000 nm (approximately 19,800 lux) in the presence or absence of Radical Sponge of 25-75 microM and did not exhibit any photo-cytotoxicity due to coexistent Radical Sponge as compared with the sham-irradiation control. Radical Sponge exerted a more marked cytoprotection at doses of 10-40 microM against UVA irradiation of 30 J/cm(2) when it was pre-irradiationally administered and rinsed out immediately before the irradiation, than when administered only during or after the irradiation, indicating the preventive rather than therapeutic or ray-sheltering effect of Radical Sponge on UVA injuries. Cytoprotection by Radical Sponge against UVA was achieved at the advisable range doses of 10-40 microM in contrast to no effect of polyvinylpyrrolidone alone; its dose-dependency was advantageous over that of VC-IP, a tetra-alkyl-esterized provitamin C, which became less cytoprotective above 20 microM. Thus, Radical Sponge is expected as an anti-UVA-preventive agent without visible-light-catalyzed cytotoxicity toward human skin keratinocytes.     

An Exclusive Human Milk-Based Diet in Extremely Premature Infants Reduces the Probability of Remaining on Total Parenteral Nutrition: A reanalysis of the data

ABSTRACT: BACKGROUND: We have previously shown that an exclusively human milk-based diet is beneficial for extremely premature infants who are at risk for necrotizing enterocolitis (NEC). However, no significant difference in the other primary study endpoint, the length of time on total parenteral nutrition (TPN), was found. The current analysis re-evaluates these data from a different statistical perspective considering the probability or likelihood of needing TPN on any given day rather than the number of days on TPN. This study consisted of 207 premature infants randomized into three groups: one group receiving a control diet of human milk, formula and bovine-based fortifier ("control diet"), and the other two groups receiving only human milk and human milk-based fortifier starting at different times in the enteral feeding process (at feeding volumes of 40 or 100 mL/kg/day; "HM40" and "HM100", respectively). The counting process Cox proportional hazards survival model was used to determine the likelihood of needing TPN in each group. RESULTS: The two groups on the completely human-based diet had an 11-14 % reduction in the likelihood of needing nutrition via TPN when compared to infants on the control diet (p = 0.0001 and p = 0.001, respectively for the HM40 and HM100 groups, respectively). This was even more pronounced if the initial period of TPN was excluded (p < 0.0001 for both the HM40 and HM100 groups). CONCLUSIONS: A completely human milk-based diet significantly reduces the likelihood of TPN use for extremely premature infants when compared to a diet including cow-based products. This likelihood may be reduced even further when the human milk fortifier is initiated earlier in the feeding process. Trial registration This study was registered at www.clinicaltrials.gov reg. # NCT00506584.     

Thoughts on the possible role of phytochrome destruction in phytochrome controlled responses

Abstract. Fluence-response curves for low-energy phytochrome responses show two steps at red light exposures c . two orders of magnitude apart. This Feature of the fluence-response relationship can be interpreted as the consequence of the following processes:

• 1. 

  Induction of a photoresponse by a very low level of Pfr.
• 2. 

  Activation of a Pfr-destroying enzyme above a threshold level of [Pfr].
• 3. 

  Dependency of the rate of Pfr destruction on [Pfr] once the threshold level is reached.

In this way, adaptation of the phytochrome control system to a broad range of light doses could be realized.     

Toxicity of antibiotics on zygotic embryos of white spruce (Picea glauca) cultured in vitro

The toxicity of kanamycin, hygromycin B, geneticin, methotrexate and cefotaxime on zygotic embryos ofPicea glauca was studied. Embryos placed on bud induction medium produced approximately 20 adventitious buds per embryo under control conditions. Addition of antibiotics reduced the number of bud-forming embryos. Using the percentage of embryos with buds as an indication of antibiotic toxicity, two-day-old explants were found to be more sensitive than nine-day-old. Kanamycin toxicity was enhanced by cefotaxime and this effect increased with increases in concentration of either antibiotic. Although no morphological difference was observed after 21 days, embryos growing on medium containing 20 g ml^–1 kanamycin showed a decrease of 73% in dry weight and 23% in protein content per embryo when compared to control embryos. Similarly, a decrease of 38% in dry weight and 40% in protein content per embryo was found in embryos on medium containing 300 g ml^–1 cefotaxime.Abbreviations BA 6 benzyl-aminopurine - EDTA ethylenediamine-tetraacetic acid - PVP 10 polyvinylpyrrolidone (MW 10,000) - Tris-HCl Tris [hydroxymethyl] amino hydrochloride NRCC No. 30262     

Acceleration of newborn rats’ development with the use of photobiomodulation and the near possibility of application in human premature babies

Photobiomodulation was explored to find evidence of stimulation during the development of newborn rats. A light chamber device was used, and rat pups were divided into groups after birth. Investigation of the process’ security was performed before the full experiment. Following a protocol of alternating illumination and mother's presence during the first 13 days, we observed that, in the group that received photobiomodulation, the pups opened their eyes faster, indicating earlier achievement of maturity. The rate of weight gain also indicates faster metabolic activity in the group that was photostimulated. This study is the first step toward the use of photobiomodulation for premature newborn human babies.     

The Chlamydomonas cell cycle is regulated by a light/dark-responsive cell-cycle switch

Cultures of the unicellular green alga Chlamydomonas reinhardii can be synchronized by light/dark cycling not only under photoautotrophic but also under mixotrophic growth conditions. We observed that cultures synchronized in the presence of acetate continue to divide synchronously for one cell-cycle period when transferred to heterotrophic growth conditions. This finding enabled us to investigate the differential effects of light on cell growth and cell division. When cells were exposed to continuous light at the beginning of the growth period they entered the division phase earlier than dark-grown cells as a consequence of an increased growth rate. Illumination at the end of the growth period, however, caused a considerable delay in cell division and an extended growth period. The light-induced delay in cell division was also observed in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), an inhibitor of photosystem II. This finding demonstrates that cell division is directly influenced by a light/dard-responsive cell-cycle switch rather than by light/dark-dependent changes in energy metabolism. The importance of this light/dark control to the regulation of the Chlamydomonas cell cycle was investigated in comparison with other control mechanisms (size control, time control). We found that the light/dard-responsive cell-cycle switch regulates the transition from G1-to S-phase. This control mechanism is effective in cells which have attained the commitment to at least one round of DNA replication and division but have not attained the maximal cell mass which initiates cell division in the light.Abbreviations dCTP deoxycytidine 5-triphosphate - DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea     

Gender differences between hypocretin/orexin knockout and wild type mice: age,body weight,body composition,metabolic markers,leptin and insulin resistance

Female hypocretin knockout (Hcrt KO) mice have increased body weight despite decreased food intake compared to wild type (WT) mice. In order to understand the nature of the increased body weight, we carried out a detailed study of Hcrt KO and WT, male, and female mice. Female KO mice showed consistently higher body weight than WT mice, from 4 to 20 months (20–60%). Fat, muscle, and free fluid levels were all significantly higher in adult (7–9 months) as well as old (18–20 months) female KO mice compared to age‐matched WT mice. Old male KO mice showed significantly higher fat content (150%) compared to age‐matched WT mice, but no significant change in body weight. Respiratory quotient (?19%) and metabolic rates (?14%) were significantly lower in KO mice compared to WT mice, regardless of gender or age. Female KO mice had significantly higher serum leptin levels (191%) than WT mice at 18–20 months, but no difference between male mice were observed. Conversely, insulin resistance was significantly higher in both male (73%) and female (93%) KO mice compared to age‐ and sex‐matched WT mice. We conclude that absence of the Hcrt peptide has gender‐specific effects. In contrast, Hcrt‐ataxin mice and human narcoleptics, with loss of the whole Hcrt cell, show weight gain in both sexes.

     

DPP-4 inhibition with linagliptin ameliorates the progression of premature aging in klotho−/− mice

Background

The potential of anti-aging effect of DPP-4 inhibitors is unknown. This study was performed to determine whether linagliptin, a DPP-4 inhibitor, could protect against premature aging in klotho?/? mice.

Methods

Klotho?/? mice exhibit multiple phenotypes resembling human premature aging, including extremely shortened life span, cognitive impairment, hippocampal neurodegeneration, hair loss, muscle atrophy, hypoglycemia, etc. To investigate the effect of linagliptin on these aging-related phenotypes, male klotho?/? mice were divided into two groups: (1) control group fed the standard diet, and (2) linagliptin group fed the standard diet containing linagliptin. Treatment with linagliptin was performed for 4 weeks. The effect of linagliptin on the above mentioned aging-related phenotypes was examined.

Results

Body weight of klotho?/? mice was greater in linagliptin group than in control group (11.1 ± 0.3 vs 9.9 ± 0.3 g; P < 0.01), which was associated with greater gastrocnemius muscle weight (P < 0.01) and greater kidney weight (P < 0.05) in linagliptin group. Thus, linagliptin significantly prevented body weight loss in klotho?/? mice. Survival rate of klotho?/? mice was greater in linagliptin group (93%) compared to control group (67%), although the difference did not reach statistical significance (P = 0.08). None of linagliptin-treated klotho?/? mice had alopecia during the treatment (P < 0.05 vs control klotho?/? mice). Latency of klotho?/? mice in passive avoidance test was larger in linagliptin group than in control group (P < 0.05), indicating the amelioration of cognitive impairment by linagliptin. Cerebral blood flow of klotho?/? mice was larger in linagliptin group than in control group (P < 0.01), being associated with greater cerebral phospho-eNOS levels (P < 0.05) in linagliptin group. Neuronal cell number in hippocampal CA1 region was greater in linagliptin group than in control group (P < 0.05). Linagliptin group had greater cerebral phospho-Akt (P < 0.05) and phospho-CREB (P < 0.05) than control group. Thus, linagliptin ameliorated brain aging in klotho?/? mice. The degree of hypoglycemia in klotho?/? mice was less in linagliptin group than in control group, as estimated by the findings of OGTT.

Conclusions

Out work provided the evidence that DPP-4 inhibition with linagliptin slowed the progression of premature aging in klotho?/? mice, and provided a novel insight into the potential role of DPP-4 in the mechanism of premature aging.

     

Tank cultivation of the red alga Palmaria palmata: Effects of intermittent light on growth rate, yield and growth kinetics

Tank cultivation of marine macroalgaeinvolves air-agitation of the algal biomassand intermittent light conditions,i.e.periodic, short light exposure of thethalli in the range of 10 s at the watersurface followed by plunging to low lightor darkness at the tank bottom andrecirculation back to the surface in therange of 1–2 min. Open questions relate toeffects of surface irradiance on growthrate and yield in such tumble cultures andthe possibility of chronic photoinhibitionin full sunlight. A specially constructedshallow-depth tank combined with a darktank allowed fast circulation times ofapproximately 5 s, at a density of 4.2 kgfresh weight (FW) m^-2s^-1. Growthrate and yield of the red alga Palmaria palmata increased over a widerange of irradiances, with no signs ofchronic photoinhibition, up to agrowth-saturating irradiance ofapproximately 1600 mol m^-2s^-1 in yellowish light supplied by asodium high pressure lamp at 16 h light perday. Maximum growth rate ranged at 12% FWd^-1, and maximum yield at 609 gFW m^-2 d^-1. This shows that highgrowth rates of individual thalli may bereached in a dense tumble culture, if highsurface irradiances and short circulationtimes are supplied. Another aspect ofintermittent light relates to possiblechanges of basic growth kinetics, ascompared to continuous light. For thispurpose on-line measurements of growth ratewere performed with a daily light reductionby 50% in light-dark cycles of 1, 2 or 3min duration during the daily light period.Growth rates at 10 °C and 50 molphoton m^-2 s^-1 dropped in allthree intermittent light regimes duringboth the main light and dark periods andreached with all three periodicitiesapproximately 50% of the control , with noapparent changes in basic growth kinetics,as compared to continuous light.     

Two Exopolyphosphatases of the Cytosol of the Yeast S. cerevisiae: Comparative Characteristics

In cell-free extracts of the yeast Saccharomyces cerevisiae that had been transferred from phosphate-deficient (–P) medium to complete (+P) medium (hypercompensation conditions), the specific and the total polyphosphatase activities increased (by 50 and 60%, respectively) compared to the control that was transferred from (+P) medium to (+P) medium. Specific and total polyphosphatase activities under hypercompensation conditions increased by 25 and 43% in cytosol, by 33 and 100% in vacuoles, and by 50 and 50% in the total membrane fraction, respectively. In contrast, the polyphosphatase activity in the cell envelope somewhat decreased compared to the control. Under the growth conditions indicated above, a novel high molecular weight polyphosphatase was revealed in the cytosol fraction along with the previously studied 40-kD polyphosphatase. Unlike the 40-kD polyphosphatase, which is most active with tripolyphosphate, this novel enzyme has a molecular mass of more than 440 kD and is most active with high molecular weight polyphosphates. This polyphosphatase is insensitive to antibodies that suppress the activity of the 40-kD polyphosphatase of the cytosol. In a number of properties, the high molecular weight polyphosphatase of the cytosol resembles the polyphosphatase of vacuoles, but it differs from the polyphosphatases of nuclei and mitochondria of S. cerevisiae. The ratio of the low and high molecular weight polyphosphatases depends on the culture growth conditions. Under hypercompensation conditions, the total activity of the high molecular weight polyphosphatase in the cytosol is five times higher than that of the 40-kD polyphosphatase. During growth without re-inoculation, the 40-kD polyphosphatase is predominant in the cytosol; its total activity in dependence on the growth stage is 3.5-12.5 times higher than the activity of the high molecular weight form.     

Lack of a Negative Effect of BCG-Vaccination on Child Psychomotor Development: Results from the Danish Calmette Study - A Randomised Clinical Trial

ObjectivesTo assess the non-specific effect of Bacillus Calmette-Guérin (BCG) vaccination at birth on psychomotor development.DesignThis is a pre-specified secondary outcome from a randomised, clinical trial.SettingMaternity units and paediatric wards at three university hospitals in Denmark.ParticipantsChildren born at gestational age (GA) 32 weeks and above. All women planning to give birth at the three sites were invited during the recruitment period. Out of 4262 randomised children, 144 were premature (GA < 37 weeks). There were 2129 children (71 premature) randomised to BCG and 2133 randomised (73 premature) to the control group.InterventionsBCG vaccination 0.05 ml was given intradermally in the upper left arm at the hospital within seven days of birth. Children in the control group did not receive any intervention. Parents were not blinded to allocation.ResultsThe mean difference in ASQ score at 12 months adjusted for age and prematurity was -0.7 points (BCG vs. control, 95% confidence interval; -3.7 to 2.4), p = 0.67, corresponding to an effect size of Cohen’s d = -0.015 (-0.082 to 0.052). The mean difference in ASQ score for premature children at 22 months was -7.8 points (-20.6 to 5.0, p = 0.23), d = -0.23 (-0.62 to 0.15).ConclusionsA negative non-specific effect of BCG vaccination at birth on psychomotor development was excluded in term children.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT01694108","term_id":"NCT01694108"}}NCT01694108     

Immunochemical ANALYSIS OF GLYCOSYLATED AND nonglycosylated dla class I antigens

Dog peripheral blood lymphocytes, when cultured with ³⁵S-methionine in the presence of tunicamycin, synthesize DLA molecules consisting of ₂-microglobulin and a heavy chain approximately 3000 daltons lower in apparent mol. wt. than observed in control cases. This difference in mol. wt. is consistent with the fact that a single N-linked carbohydrate side chain is present on the heavy chain of DLA class I antigens. There is no evidence of polymorphism in the DLA light chain ( ₂m). Both glycosylated and nonglycosylated forms of the heavy chain, however, show microheterogeneity, which can be related to tissue-type. Analysis by two-dimensional electrophoresis shows that the biochemical heterogeneity in the DLA heavy chain is less than expected from DLA serology, and less than found in HLA class I antigens. The data are consistent with the fact that the products of only a single DLA class I locus are detected.Abbreviations used in this paper ₂m beta-2-microglobulin - 2D two dimensional - DLA dog MHC - HLA human MHC - Ia I-region associated - MHC major histocompatibility complex - PBL peripheral blood lymphocytes - PHA-M phytohaemagglutinin-muco - pI isoelectric point - RLA rabbit MHC - SDS-PAGE sodium dodecyl sulfate-polyacrylamide gel electrophoresis     

Effect of l-aminocyclopropane-l-carboxylic acid,silver nitrate,and norbornadiene on plant regeneration from maize callus cultures

The effect of the ethylene antagonists norbornadiene and silver nitrate and the ethylene precursor l-aminocyclopropane-l-carboxylic acid (ACC) on Zea mays plant regeneration was studied. A 12-fold increase in plant regeneration, as measured by number of plants obtained per gram fresh weight from callus cultures of maize inbreds Pa91 and H99, was obtained by 250 M norbornadiene and 100 M silver nitrate treatments. An increase in amout of nonregenerable tissue and a 68% decrease in plant regeneration were associated with callus treated with 1 mM ACC. Ethylene emanation from 1 mM ACC treated callus reached a maximum of 170 nl g^–1 h^–1 after 3 days compared to 7 nl g^–1 h^–1 for the control. The free proline content was up to 80% lower in 1 mM ACC treated callus grown for 30 days on medium with or without 12 mM proline, respectively, as compared to each control. These studies indicate that ethylene action inhibitors such as norbornadiene and silver nitrate can be used to increase plant regeneration efficiency from maize callus cultures.Abbreviations ACC l-aminocyclopropane-l-carboxylic acid - gfw gram fresh weight     

Intervention based on BASNEF model increases exclusive breastfeeding in preterm infants in Iran: a randomized controlled trial

Background

The objective of this study is to determine the effect of a consultation model, Beliefs, Attitudes, Subjective Norms and Enabling Factors (BASNEF), and the counselling steps using GATHER-Greet clients, Ask clients about themselves, Tell clients about their choices, Help clients choose, Explain what to do, and Return for follow-up-on the continuation rates of exclusive breastfeeding in mothers of premature infants.

Methods

This is a randomized controlled clinical trial carried out on 124 mothers with premature infants hospitalized in Fatemieh Hospital, city of Hamadan, in 2014. Participants were randomly assigned to either the intervention or control groups. The initial demographic questionnaire carried out in both groups included three questions about the continuation of exclusive breastfeeding, BASNEF, a checklist related to the lactation performance documented by mothers and the weight gain of their infants. Five breastfeeding consultation sessions based on the BASNEF model and counselling steps using GATHER, were held for the mothers in the intervention group for five consecutive days. Then follow-up weight gain and the questionnaire completion were performed in both groups at 1, 2, 3 and 4 months after the intervention.

Results

Baseline characteristics were similar in the two groups. There were no significant differences between both groups in the rate of exclusive breastfeeding, lactation performance and infant weight at baseline. The intervention group had significantly higher rates of exclusive breastfeeding, 72.6% versus the control group of 16.1%, at the end of the 4 month follow-up. Also the intervention group had significantly higher mean scores of lactation performance (8.62?±?2.08 vs 6.40?±?1.84 in the control group) and infant weight (5694.80?±?779.43 vs 4760.17?±?859.12 in the control group) at the end of the 4 month follow-up.

Conclusion

Breastfeeding consultation of mothers based on the BASNEF model and using GATHER counselling steps increased the rate of exclusive breastfeeding, lactation performance and weight gain of premature infants. Therefore, breastfeeding counselling sessions are recommended for all mothers of premature infants.

Trial registration

Iranian Registry of Clinical Trials number IRCT2014111013405N6 and date registered, January 5, 2015.

     

Does Visceral Osteopathic Treatment Accelerate Meconium Passage in Very Low Birth Weight Infants?- A Prospective Randomized Controlled Trial

Background

To determine whether the complementary approach of visceral manipulative osteopathic treatment accelerates complete meconium excretion and improves feeding tolerance in very low birth weight infants.

Methods

This study was a prospective, randomized, controlled trial in premature infants with a birth weight <1500 g and a gestational age <32 weeks who received a visceral osteopathic treatment 3 times during their first week of life or no treatment.

Results

Passage of the last meconium occurred after a median of 7.5 days (95% confidence interval: 6–9 days, n = 21) in the intervention group and after 6 days (95% confidence interval: 5-9 days, n = 20,) in the control group (p = 0.11). However, osteopathic treatment was associated with a 8 day longer time to full enteral feedings (p = 0.02), and a 34 day longer hospital stay (Median = 66 vs. 100 days i.e.; p=0.14). Osteopathic treatment was tolerated well and no adverse events were observed.

Conclusions

Visceral osteopathic treatment of the abdomen did not accelerate meconium excretion in VLBW (very low birth weight)-infants. However infants in the osteopathic group had a longer time to full enteral feedings and a longer hospital stay, which could represent adverse effects. Based on our trial results, we cannot recommend visceral osteopathic techniques in VLBW-infants.

Trial registration

Clinical trials.gov: NCT02140710     

The effect of different night conditions on the CO2 fixation in a lichen Xanthoria parietina

CO₂ fixation was studied in a lichen, Xanthoria parietina, kept in continuous light, and with cyclic changes in light intensity, dark period or temperature. The diurnal and seasonal courses of CO₂ exchange were followed. The rate of net photosynthesis was observed to fall from morning to evening, and this decline was more pronounced in winter than in summer. The maximal net photosynthetic rate, 223 ng CO₂g^-1dws^-1, occured in winter and the minimum, 94 ng CO₂g^-1dws^-1, late in spring. The light compensation point in summer was four times as high as in winter. In continuous light (180 or 90 mol photons m^-2s^-1, 15°C) net photosynthesis decreased noticeably during one week, falling below the level maintained in a 12 h light: 12 h dark cycle. Photosynthetic activity did not decrease, however, in lichens held in continuous light (90 mol photons m^-2s^-1) with cyclic changes of temperature (12 h 20 °C: 12 h 5 °C). Active photosynthesis was also maintained in light of cyclically changing intensity (12 h: 12 h, 15 °C) when night-time light was at least 75% lower than illumination by day. A dark period of 4 hours in a 24-h light:dark cycle was sufficient to keep CO₂ fixation at the control level. It seems that plants need an unproductive period during the day to survive and this can be induced by fluctuations in light and/or temperature.     

Persistent effects of changes in phytochrome status on internode growth in light-grown mustard: Occurrence,kinetics and locus of perception

Extension growth of the first internode in fully de-etiolated mustard (Sinapis alba L.) seedlings (11–12.5 d old) is under the control of both the current phytochrome photoequilibrium (Pfr/P, ratio of the far-red-absorbing form of phytochrome to total phytochrome) and that established by short (<12 h) pretreatments. Plants were pretreated with either light pulses providing different calculated Pfr/P followed by dark incubations of different durations (a), or with a 12-h period of white light establishing different Pfr/P (b). After the pretreatments, the plants received either light pulses providing different Pfr/P, followed by dark incubations (c), or continuous white light with or without addtional far-red light (d). Thus, four experimental approaches were followed: (a)(c); (a)(d); (b)(c) and (b)(d). Extension growth during the second period (c or d) was not only affected by the current phytochrome status, but also by that established during the pretreatment period (a or b). The results show the existence of a long-term promotion of stem growth which persists after the end of the low Pfr/P pretreatment. This effect is different from the previously reported rapid effect of far-red light added to background white light as follows: (i) the duration of low Pfr/P required to effect a full response is longer (2.5 h); (ii) the duration of the promotion after returning to high Pfr/P is longer (approx. 24 h) and (iii) the locus of perception is mainly in the leaves, rather than the growing internode.Abbreviations FR far-red light - PAR photosynthetically active radiation - Pfr/P ratio between the FR-absorbing form and total phytochrome - R red light - WL white light     

Effect of washing on the plasma membrane and on stress reactions of cultured rose cells

The effects of plant growth regulators, light intensity, and end-of-day (EOD) light quality treatments on node and microtuber induction (% of cultures with microtubers) and development (fresh weight of microtubers) in yam (Dioscorea alata L. cv. Oriental) cultures were investigated. Nodal segments were excised from plantlets cultured on tuberization medium containing growth regulators and exposed to various light treatments. Absciscic acid (1 M) stimulated and cytokinins (2.5 M) inhibited microtuber development from yam nodal segments cultured on Mantell's and Hugo's full-strength tuberization medium under 8-h photoperiods. EOD far-red (FR) light inhibited microtuber induction and development and enhanced node formation. EOD FR light effects were nullified by immediately following the FR treatment with red light. This suggested the involvement of phytochrome in these processes. The lowest light intensity evaluated (12 mol m^–2 s^–1) inhibited microtuber, root and shoot production as compared to light intensities of 42, 72 and 102 mol m^–2 s^–1. Kinetin (2.5 m) in half-strength tuberization medium inhibited microtuber induction and development but did not affect node production in the light intensity evaluation.Abbreviations ABA abscisic acid - BA 6-benzylaminopurine - 2iP 6-(c,c-dimethylallylamino)-purine - NAA napthaleneacetic acid - R light red light - FR light far-red light - EOD light end-of-day light