Effet de la salinité sur la fluorescence chlorophyllienne, la teneur en proline et la production florale de trois espèces ornementales

Effect of Chloride Sodium on Chlorophyll Fluorescence, Plant Proline Content and Flowers Production of Three Ornamental Species. Three ornamental species (Zinnia elegans, Tagetes patula and Petunia hybrida) were used to test sodium chloride effect on chlorophyll fluorescence, plant proline content and flowers production. Three treatments were used in this trial: 0, 2 and 4 g of Nacl.l-1 of irrigation water. The results showed that chlorophyll fluorescence was not affected by sodium chloride treatment but plant proline content increased and flowers production decreased as NaCl doses increase

Multiplication et bulbaison in vitro du glaïeul (Gladiolus grandiflorus Hort.)

In vitro Multiplication and Bulb Formation of (Gladiolus grandiflorus Hort.). In order to set up a new bulb formation and micropropagation of gladiolus in vitro, trials were undertaken using two ornemental gladiolus cultivars 'Peter pears' and 'White friend ship'. The explants used are apical buds with 2 to 3 mm length taken from the cormes. In vitro initiation and multiplication were done for the two cultivars on Murashige and Skoog medium to which 2 mg. l-1 of BA and 0.5 mgl-1 of AIB were added. In vitro root development and bulb formation have been occurred in MS Agar Agar medium with 0.5 mg.l-1 of AIB 30 days later than the same MS medium containing 6% of saccharose and without Agar

Effect of Thiourea on Yield and Quality of Potato (Solanum tuberosum L.)

A field experiment was carried out to study the effect of five concentrations (0, 250, 500, 750 and 1000 mM) of thiourea application on mother tubers on yield and quality attributes of harvested potato, variety Spunta in the region of Chott-Mariem in Tunisia. Treated tubers (Ш = 50 mm) were planted in field after breaking dormancy at a spacing of 80 cm x 30 cm according to completely randomized design (CRD) in three replications. Quality attributes of potato tubers especially fresh matter and dry matter of plant, total reducing sugars in leaves, tuber yield, number and diameter of tubers per plant and number of sprouts per tuber was measured. Soluble proteins and starch content in potato tubers were also quantified.In general we noted that application of thiourea showed significant influence on yield and on quality of tubers comparing to control. Maximum tuber yield per plant, maximum number of tubers per plant and maximum starch content was recorded with 250 mM of thiourea. Moreover, highest dry matter of potato plant was found also at this concentration. While increasing dose of thiourea thereafter it showed slight significant improvement and do not affect significantly the diameter of tubers comparing to control

PHYSIOLOGICAL MECHANISMS FOR POTATO DORMANCY RELEASE AND SPROUTING: A REVIEW

Potato ( Solanum tuberosum \ua0L.) tubers undergo a period of dormancy, during which visible bud growth is inhibited. The length of the dormancy is determined by environmental, physiological and hormonal control mechanisms. Dormancy is the final stage of tuber life, which serves to preserve tubers as organs of vegetative reproduction under unfavourable growth conditions. Since the duration of potato tuber dormancy and sprouting time bear significant economic importance, this review considers the regulation of dormancy and sprouting of potato by phytohormones and reactive oxygen species. Two phytohormones, ABA and ethylene suppress tuber sprouting; however, the exact role of ethylene remains to be elucidated. Cytokinins and gibberellins are required for bud breaking and sprout growth, respectively. The auxin seems to play a role in vascular development. Thus, tuber dormancy and sprouting can be controlled in potato by manipulation of Reactive Oxygen Species (ROS), especially H2O2\ua0metabolism via the inhibition of catalase (CAT) activity.The possible mechanisms by which CAT inhibitors or H2O2\ua0overcome dormancy and promote sprouting in the potato tuber are discussed.La pomme de terre ( Solanum tuberosum \ua0L.) conna\ueet une p\ue9riode de dormance durant laquelle la germination des bourgeons visibles est inhib\ue9e. La dur\ue9e de dormance est d\ue9termin\ue9e par des m\ue9canismes de contr\uf4le environnemental, physiologique and hormonal. La dormance est le stade final de la vie des tubercules servant \ue0 pr\ue9server les tubercules comme organes de reproduction v\ue9g\ue9tative sous condition de germination d\ue9favorables. Etant donn\ue9 que la dur\ue9e de la dormance des tubercules de la pomme de terre et le temps de rejet rev\ueatent une importance \ue9conomique significative, cette revue consid\ue8re la r\ue9gulation de la dormance et le rejet de la pomme de terre par des hormones et d\u2019esp\ue8ces r\ue9actives d\u2019oxyg\ue8ne (ROS). Deux phytohormones\ua0; ABA et \ue9thyl\ue8ne emp\ueachent le rejet des tubercules\ua0; par ailleurs, le r\uf4le extractif de l\u2019\ue9thyl\ue8ne reste \ue0 \ue9lucider. Les cytokinines and les gibb\ue9rellines sont n\ue9cessaires dans l\u2019\ue9limination des bourgeons et la croissance des rejets, respectivement. L\u2019auxine semble jouer un r\uf4le dans le d\ue9veloppement vasculaire. Ainsi, la dormance et les rejets des tubercules peuvent \ueatre contr\uf4l\ue9s par manipulation d\u2019esp\ue8ces r\ue9actives d\u2019oxyg\ue8ne (ROS), sp\ue9cialement le m\ue9tabolisme du H2O2\ua0\ue0 travers l\u2019inhibition de l\u2019activit\ue9 de la catalase (CAT). Les m\ue9canismes possibles par lesquels les inhibiteurs du CAT ou H2O2\ua0 surmontent la dormance et facilitent le rejet de la pomme de terre sont discut\ue9s

Zn treatment effects on biological potential of fennel bulbs as affected by in vitro digestion process

Zn treatment effects on the stability of polyphenols, MDA (malondialdehyde) content, antioxidant and lipoxygenase inhibition activities of two varieties of fennel bulbs were studied by using an in vitro gastrointestinal digestion model. Likewise, the effect of Zn on viability cells of E. coli was also performed. The results revealed that high amounts of total phenolic and flavonoid compounds were released during the digestion process, especially after the intestinal phase. Additionally, the antioxidant and lipoxygenase inhibitory activity were affected by the gastrointestinal digestion process and seems to be correlated with total phenol contents. On the other hand, the viability of E. coli was not affected by the activity of our tested bulbs during passage through the artificial digestion model, but the treated bulbs activity contribute relatively to the inhibition growth of bacteria. The survival of E. coli in fennel bulbs was challenged with simulated gastrointestinal fluids and the results showed that the E. coli strains, despite having experienced a viability reduction at the intestinal phase, were able to overcome the exposure to the gastrointestinal synthetic fluids. This E. coli ability reinforces the need for good hygienic measures to assure safe fresh produce, even for those that are rich in antibacterial compounds.info:eu-repo/semantics/publishedVersio

Modulation of Cellular Hsp72 Levels in Undifferentiated and Neuron-Like SH-SY5Y Cells Determines Resistance to Staurosporine-Induced Apoptosis

Increased expression of Hsp72 accompanies differentiation of human neuroblastoma SH-SY5Y cells to neuron-like cells. By modulating cellular levels of Hsp72, we demonstrate here its anti-apoptotic activity both in undifferentiated and neuron-like cells. Thermal preconditioning (43°C for 30 min) induced Hsp72, leading to cellular protection against apoptosis induced by a subsequent treatment with staurosporine. Preconditioned staurosporine-treated cells displayed decreased Bax recruitment to mitochondria and subsequent activation, as well as reduced cytochrome c redistribution from mitochondria. The data are consistent with Hsp72 blocking apoptosis upstream of Bax recruitment to mitochondria. Neuron-like cells (with elevated Hsp72) were more resistant to staurosporine by all measured indices of apoptotic signaling. Use of stable transfectants ectopically expressing moderately elevated levels of Hsp72 revealed that such cells in the undifferentiated state showed enhanced resistance to staurosporine-induced apoptosis, which was even more robust after differentiation to neuron-like cells. Overall, the protective effects of differentiation, thermal preconditioning and ectopic Hsp72 expression were additive. The strong inverse correlation between cellular Hsp72 levels and susceptibility to apoptosis support the notion that Hsp72 acts as a significant neuroprotective factor, enabling post-mitotic neurons to withstand potentially lethal stress that induces apoptosis

Simian Immunodeficiency Virus Infection of Chimpanzees (Pan troglodytes) Shares Features of Both Pathogenic and Non-pathogenic Lentiviral Infections.

The virus-host relationship in simian immunodeficiency virus (SIV) infected chimpanzees is thought to be different from that found in other SIV infected African primates. However, studies of captive SIVcpz infected chimpanzees are limited. Previously, the natural SIVcpz infection of one chimpanzee, and the experimental infection of six chimpanzees was reported, with limited follow-up. Here, we present a long-term study of these seven animals, with a retrospective re-examination of the early stages of infection. The only clinical signs consistent with AIDS or AIDS associated disease was thrombocytopenia in two cases, associated with the development of anti-platelet antibodies. However, compared to uninfected and HIV-1 infected animals, SIVcpz infected animals had significantly lower levels of peripheral blood CD4+ T-cells. Despite this, levels of T-cell activation in chronic infection were not significantly elevated. In addition, while plasma levels of β2 microglobulin, neopterin and soluble TNF-related apoptosis inducing ligand (sTRAIL) were elevated in acute infection, these markers returned to near-normal levels in chronic infection, reminiscent of immune activation patterns in 'natural host' species. Furthermore, plasma soluble CD14 was not elevated in chronic infection. However, examination of the secondary lymphoid environment revealed persistent changes to the lymphoid structure, including follicular hyperplasia in SIVcpz infected animals. In addition, both SIV and HIV-1 infected chimpanzees showed increased levels of deposition of collagen and increased levels of Mx1 expression in the T-cell zones of the lymph node. The outcome of SIVcpz infection of captive chimpanzees therefore shares features of both non-pathogenic and pathogenic lentivirus infections.This work was supported by the Biotechnology and Biological Sciences Research Council and by the Wellcome Trust.This is the final version of the article. It first appeared from PLOS via http://dx.doi.org/10.1371/journal.ppat.100514

EFFECT OF HYDROGEN PEROXIDE AND THIOUREA ON DORMANCY BREAKING OF MICROTUBERS AND FIELD-GROWN TUBERS OF POTATO

Potato ( Solanum tuberosum L.) microtubers or field-grown tubers have a dormant apical bud (also called tuber dormancy). They do not readily sprout even if environmental conditions are favorable, including optimum temperature and humidity. The objective of this study was to evaluate the involvement of hydrogen peroxide (by direct or indirect application of thiourea, a catalase inhibitor) in dormancy release and sprouting of potato microtubers and tubers was evaluated using two complementary experiments. First, the kinetics of the sprouting (percentage of sprouted microtubers with time) was examined on microtubers planted in peat and cultivated in a glasshouse after exogenous application of different concentrations of hydrogen peroxide (20, 40 and 60 mM) and thiourea (250, 50 0 and 750 mM). Second, the sprouting kinetics was examined on field-grown tubers during storage, after application of hydrogen peroxide (20, 40, 60 and 80 mM) and thiourea (250, 500, 750 and 1000 mM). Their sprouting capacity was also evaluated. Then, kinetics of field emergence of treated and sprouted tubers was examined after planting them in a field. Direct application of hydrogen peroxide or application of catalase inhibition through thiourea application on the release of dormancy promote sprouting on potato microtubers and field-grown tubers. Results showed that hydrogen peroxide (20 mM) caused rapid and synchronous sprouting of microtubers; while higher concentrations (40 and 60 mM), caused asynchronous sprouting. Thiourea at a concentration of 250 mM was the most effective in reducing the dormancy period and increasing the number of sprouted microtubers. In field experiment, sprouting was optimal when tubers were treated with 60 mM of hydrogen peroxide; whereas at a lower concentration, sprouting was less stimulated. In addition, tubers treated with 250 mM thiourea had maximum sprouting and better sprouting capacity. It is clear that both substances affect hormonal regulation and antioxidant enzymes, leading to dormancy release in both: microtubers and tubers.Les microtubercules de la pomme de terre ( Solanum tuberosum L.) ou bien les tubercules cultivées en champs sont dotées d’une dormance des tubercules. Elle ne poussent pas facilement, même si les conditions environnementales sont favorable, incluant température optimal et l’ humidité. L’objectif de cette thiourea, une catalase inhibitrice) dans la libération de la dormance et la germination des microtubercules de pomme de terre était évalué utilisant deux essais complémentaires. D’abord, la cinétique de germination (pourcentage de microtubercules germées avec le temps) était examinee sur des microtubercules plantées sur susbtract tourbeux et cultivées dans une serre après application exogène de différentes concentrations du peroxide d’hydrogène (20, 40 et 60 mM) et thiourea (250, 50 0 et 750 mM). Deuxièmement, la cinétique de germination était examinée pendant le stockage sur des tubercules cultivées en champ après application du peroxide d’hydrogène (20, 40, 60 et 80 mM) et thiourea (250, 500, 750 et 1000 mM). Leur capacité de germination était évaluée. En suite, la cinétique d’émergence au champs des tubercules traitées et germées était examinée après les avoir plantées au champs. L’application directe du peroxide d’hydrogène ou application de la catalase inhibitrice à travers l’ application du thiourea sur la liberation de la dormance promeut la germination des microtbercules ainsi que les tubercules produites en champs. Les résultats ont montré que le peroxide d’hydrogène (20 mM) ont cause un rapide et une germination synchronisée des microtubercules; alors que les concentration plus élevées (40 et 60 mM), ont cause une germination non synchronisées. Thiourea avec une concentration de 250 mM était le plus efficace en terme de réduction de la période de dormance et l’augmentation du nombre des microtubercules germées. Dans l’essai en champs, la germination était optimal lorsque les tubercules étaient traitées avec 60 mM du peroxide d’ hydrogen; pendant qu’ à une basse concentration, la germination était moins stimulées. En plus, les tubercules treatées avec 250 mM de thiourea avaient un maximum de germination et une meilleur capacité de germination. Il est claire que toutes les deux substances affectent la regulation hormonale et les enzymes antioxidants, conduisant ainsi à la libétation de la dormance dans les microtbercules et les tubercules