Hormonal Profile in Ovaries of Mandarin Varieties with Differing Reproductive Behaviour

The endogenous levels of 13 gibberellins (GAs), three cytokinins (CKs), abscisic acid (ABA), indole-3-acetic acid (IAA) and jasmonic acid (JA) were analyzed in naturally pollinated ovaries of three mandarin cultivars selected for their different capacity to produce seeds and their differing parthenocarpic ability. The varieties compared were Murcott (pollen self-compatible, highly seeded), Moncada (self-incompatible, moderately seeded), and Moncalina (pollen sterile, seedless), obtained from Moncada by bud gamma-irradiation. As expected, the 13-hydroxylation pathway was predominant in ovaries and our results further indicate that cultivar differences exist in GA metabolism. The active gibberellin GA(1) levels in ovaries seems to be related with presence of fertilized ovules and, therefore, with the ability to produce the seeds of a variety. Sterility gamma irradiation arrested the biosynthesis of GA(1) and its precursor GA(19) in Moncalina ovaries if compared to Moncada. The productive efficiency of the studied cultivars also indicated that fruit set depends strongly on the GA(1) level achieved by ovaries, which is also closely related with carbohydrate content. The study of the expression of gibberellin-oxidase genes showed that the pollination/fecundation process enhances GA20ox2 and GA3ox1 activities in naturally pollinated Murcott and Moncada ovaries compared with unpollinated Murcott and Moncalina, respectively. GA2ox1 expression was lower in the ovaries of the highly seeded cultivar Murcott than in those of Moncada or Moncalina. Unpollinated Murcott ovaries contained much lower levels of GA(1) and IAA than the naturally pollinated ovaries of this cultivar. Conversely, unpollinated ovaries, which exhibited 100 % abscission, had more ABA and JA contents. Cytokinin activity seemed constitutive and independent of pollination/fecundation. However, trans-zeatin (t-Z) and 2-isopentenyl adenine (2-IP) concentrations were higher in Murcott ovaries than in Moncada/Moncalina.We thank Drs. Isabel Lopez-Diaz and Esther Carrera for the hormone quantification carried out at the Plant Hormone Quantification Service, IBMCP, Valencia, Spain. This work has been supported by two research Projects, RTA2011-00052-00-00 and RTA2011-00114-00-00, from INIA (Ministerio de Educacion y Ciencia, Spain), by the European Community FEDER and ESF funds, and by the Conselleria de Agricultura, Pesca y Alimentacion (Generalitat Valenciana, Spain).Bermejo, A.; Primo Millo, E.; Agustí Fonfría, M.; Mesejo Conejos, C.; Reig Valor, C.; Iglesias Fuente, DJ. (2015). Hormonal Profile in Ovaries of Mandarin Varieties with Differing Reproductive Behaviour. Journal of Plant Growth Regulation. 34(3):584-594. https://doi.org/10.1007/s00344-015-9492-yS584594343Ali-Dinar HM, Krezdorn AH, Wheaton TA (1988) The sexual-hormonal relation in citrus during fruit set. Acta Hortic 218:159–175Ben-Cheikh W, Perez-Botella J, Tadeo FR, Talón M, Primo-Millo E (1997) Pollination increases gibberellin levels in developing ovaries of seeded varieties of citrus. Plant Physiol 114:557–564Bermejo A, Pardo J, Cano A (2011) Influence of gamma irradiation on seedless citrus production: pollen germination and fruit quality. Food Nutr Sci 2:169–180Brewbaker JL, Kwack BH (1963) The essential role of calcium ion in pollen germination and pollen tube growth. Am J Bot 50:859–865Bustin SA (2002) Quantification of mRNA using real-time reversetranscription PCR (RT-PCR): trends and problems. J Mol Endocrinol 29:23–39Castle WS, Phillips RL (1980) Performance of ‘Marsh’ grapefruit and ‘Valencia’ orange trees on eighteen rootstocks in close planting. J Am Soc Hortic Sci 105:496–499De Jong M, Mariani C, Vriezen WH (2009) The role of auxin and gibberellin in tomato fruit set. J Exp Bot 60:1523–1532Frost HB, Soost RK (1968) Seed reproduction: development of gametes and embryos. In: Reuther W, Batchelor LD, Webber HJ (eds) The citrus industry, vol 2. University of California, California, pp 290–320Gambetta G, Gravina A, Fasiolo C, Fornero C, Galiger S, Inzaurralde C, Rey F (2013) Self-incompatibility, parthenocarpy and reduction of seed presence in “Afourer” mandarin. Sci Hortic 164:183–188García-Martínez JL, García-Papi MA (1979) The influence of gibberellic acid, 2,4-dichlorophenoxyacetic acid and 6-benzylaminopurine on fruit set of Clementine mandarin. Sci Hortic 10:285–293García-Papi MA, García-Martínez JL (1984) Endogenous plant growth substances content in young fruits of seeded and seedless Clementine mandarin as related to fruit set and development. Sci Hortic 22:265–274Giacomelli L, Rota-Stabelli O, Masuero D, Acheampong AK, Moretto M, Caputi L, Vrhovsek U, Moser C (2013) Gibberellin metabolism in Vitis vinifera L. during bloom and fruit set: functional characterization and evolution of grapevine gibberellin oxidases. J Exp Bot 64:4403–4419Goodstein DM, Shu S, Howson R, Neupane R, Hayes RD, Fazo J, Mitros T, Dirks W, Hellsten U, Putnam N, Rokhsar DS (2012) Phytozome: a comparative platform for green plant genomics. Nucleic Acid Research, 40 (Database issue): D1178–D1186Goren R, Huberman M, Goldschmidt E (2003) Girdling: physiological and horticultural aspects. Hortic Rev 30:1–36Hearn CJ (1986) Development of seedless grapefruit cultivars through budwood irradiation. J Am Soc Hort Sci 111:304–306Hernandez-Miñana FM, Primo-Millo E (1989) Endogenous cytokinins in developing fruits of seeded and seedless Citrus cultivars. J Exp Bot 40:1127–1134Hernandez-Miñana FM, Primo-Millo E (1990) Studies on endogenous cytokinins in Citrus. J Hort Sci 65:596–601Huerta L, García-Lor A, García-Martínez JL (2009) Characterization of gibberellin 20-oxidases in the citrus hybrid Carrizo citrange. 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Auxin and Gibberellin Interact in Citrus Fruit Set

[EN] Gibberellins (GA) and auxin (indole-3-acetic acid, IAA) are considered the main compounds involved in the induction of fruit set. Citrus trees flower profusely but exhibit dramatically low fruit set rates and, in particular, seeded orange cultivars also require pollination for fruit to adequately set. Consequently, they represent an excellent model to investigate the interactions between both hormones and their effect on fruit set and development. Unpollinated ovaries from 'Pineapple' sweet orange trees were treated with IAA and pollinated ones with TIBA (2,3,5-triiodobenzoic acid, inhibitor of auxin transport), and changes in ovaries were registered shortly after the treatments. The highest IAA levels were found in unpollinated ovaries treated with auxin (twofold increase compared to pollinated ones), and the lowest corresponded to pollinated ones supplemented with TIBA (30% reduction). GA content also differed substantially among samples. In general, expression of the GA-biosynthetic gene GA20ox2 in the ovule and pericarp paralleled the changes in GA(20) content in both tissues, and also expression of GA3ox1 and GA(1) content but only in the ovule. The levels of these GA in unpollinated ovaries were promoted in response to exogenous IAA, whereas expression of the GA-inactivation gene GA2ox1 and the concentration of the GA-catabolite GA(8) were reduced by this treatment. Significantly, treatments with GA(3) or IAA to unpollinated ovaries recovered fruit set to the level reached by free pollinated ones. Our study demonstrates that IAA alters GA metabolism in citrus leading to marked changes in the active GA(1) levels in ovules and pericarp, mainly through the regulation of GA-biosynthetic genes and the inhibition of the catabolic pathway.We thank Drs. Isabel Lopez-Diaz and Esther Carrera for the hormone quantification carried out at the Plant Hormone Quantification Service, IBMCP, Valencia, Spain. Thanks are due to Teresa Sabater from the IBMCP, for her help. This work has been supported by two research projects, RTA2013-00024-CO2-01 from INIA (Ministerio de Economia y Competitividad, Spain) and IVIA-51423 from Conselleria de Agricultura (Generalitat Valenciana, Valencia, Spain).Bermejo, A.; Granero, B.; Mesejo Conejos, C.; Reig Valor, C.; Tejedo, V.; Agustí Fonfría, M.; Primo-Millo, E.... (2018). Auxin and Gibberellin Interact in Citrus Fruit Set. Journal of Plant Growth Regulation. 37(2):491-501. https://doi.org/10.1007/s00344-017-9748-9S491501372Ali-Dinar HM, Krezdorn AH, Wheaton TA (1988) The sexual-hormonal relation in citrus during fruit set. Acta Hortic 218:159–175Barendse GWM, Kepczynski J, Karssen CM, Koorneef M (1986) The role of endogenous gibberellins during fruit and seed development: studies on gibberellin-deficient genotypes of Arabidopsis thaliana. 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Inflammaging: Implications in Sarcopenia

In a world in which life expectancy is increasing, understanding and promoting healthy aging becomes a contemporary demand. In the elderly, a sterile, chronic and low-grade systemic inflammation known as “inflammaging” is linked with many age-associated diseases. Considering sarcopenia as a loss of strength and mass of skeletal muscle related to aging, correlations between these two terms have been proposed. Better knowledge of the immune system players in skeletal muscle would help to elucidate their implications in sarcopenia. Characterizing the activators of damage sensors and the downstream effectors explains the inference with skeletal muscle performance. Sarcopenia has also been linked to chronic diseases such as diabetes, metabolic syndrome and obesity. Implications of inflammatory signals from these diseases negatively affect skeletal muscle. Autophagic mechanisms are closely related with the inflammasome, as autophagy eliminates stress signaling sent by damage organelles, but also acts with an immunomodulatory function affecting immune cells and cytokine release. The use of melatonin, an antioxidant, ROS scavenger and immune and autophagy modulator, or senotherapeutic compounds targeting senescent cells could represent strategies to counteract inflammation. This review aims to present the many factors regulating skeletal muscle inflammaging and their major implications in order to understand the molecular mechanisms involved in sarcopenia

Neurogenic Potential of the 18-kDa Mitochondrial Translocator Protein (TSPO) in Pluripotent P19 Stem Cells

The 18-kDa translocator protein (TSPO) is a key mitochondrial target by which different TSPO ligands exert neuroprotective effects. We assayed the neurogenic potential of TSPO to induce the neuronal differentiation of pluripotent P19 stem cells in vitro. We studied changes in cell morphology, cell proliferation, cell death, the cell cycle, mitochondrial functionality, and the levels of pluripotency and neurogenesis of P19 stem cells treated with the TSPO ligand, PK 11195, in comparison to differentiation induced by retinoid acid (RA) and undifferentiated P19 stem cells. We observed that PK 11195 was able to activate the differentiation of P19 stem cells by promoting the development of embryoid bodies. PK 11195 also induced changes in the cell cycle, decreased cell proliferation, and activated cell death. Mitochondrial metabolism was also enhanced by PK 11195, thus increasing the levels of reactive oxygen species, Ca2+, and ATP as well as the mitochondrial membrane potential. Markers of pluripotency and neurogenesis were also altered during the cell differentiation process, as PK 11195 induced the differentiation of P19 stem cells with a high predisposition toward a neuronal linage, compared to cell differentiation induced by RA. Thus, we suggest a relevant neurogenic potential of TSPO along with broad therapeutic implications

Biosynthesis and Contents of Gibberellins in Seeded and Seedless Sweet Orange (Citrus sinensis L. Osbeck) Cultivars

[EN] In this work, we study the capacity to biosynthesize gibberellins (GA) of ovules (either fertilised or unfertilised), developing seeds and pericarp from fruitlets and their relation with fruit set capacity. Experiments were performed in adult, 12-year-old trees of seeded (Pineapple) and seedless parthenocarpic (Washington navel) sweet orange [Citrus sinensis L. Osbeck] cultivars. The activity of GA20-, GA3- and GA2-oxidases and gibberellin levels were measured in the ovules and pericarp of fruitlets in different development states. The results indicate that ovules are the main sites of gibberellin synthesis in fruitlets during the post-anthesis period. The most intense GA(1) synthesis-coincident with the highest expression of GA20ox2, GA3ox1 and GA2ox1-was detected in the ovules of the seeded cultivar, probably induced by fecundation and associated with low early fruitlet abscission rates. By contrast, the low activity detected in the sterile cultivar appears to be rather developmentally or constitutively regulated. As a fruitlet develops, the GA(1) concentration is augmented in the pericarp in comparison to ovules or developing seeds, and levels therein did not exhibit noticeable differences between varieties. Furthermore, developing seeds from pineapple had higher GA(1) content than the unfertilised abortive ovules from Washington navel. Taken together, data suggest a main role for this hormone in the control of fruitlet abscission, and also demonstrate a function in seed development.We thank Drs. Isabel Lopez-Diaz and Esther Carrera for the hormone quantification carried out at the Plant Hormone Quantification Service, IBMCP, Valencia, Spain. Thanks are due to Teresa Sabater from the IBMCP, for their help. This work has been supported by two research projects, RTA2013-00024-CO2-01 from INIA (Ministerio de Economia y Competitividad, Spain) and IVIA-5423 from Conselleria de Agricultura (Generalitat Valenciana, Valencia, Spain).Bermejo, A.; Martínez Alcántara, B.; Martínez Cuenca, MR.; Yuste Gallasch, R.; Mesejo Conejos, C.; Reig Valor, C.; Agustí Fonfría, M.... (2016). Biosynthesis and Contents of Gibberellins in Seeded and Seedless Sweet Orange (Citrus sinensis L. Osbeck) Cultivars. Journal of Plant Growth Regulation. 35(4):1036-1048. https://doi.org/10.1007/s00344-016-9602-5S10361048354Ben-Cheikh W, Perez-Botella J, Tadeo FR, Talón M, Primo-Millo E (1997) Pollination increases gibberellin levels in developing ovaries of seeded varieties of citrus. Plant Physiol 114:557–564Bustin SA (2002) Quantification of mRNA using real-time reverse transcription PCR (RT-PCR): trends and problems. 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Chronic Treatment with Melatonin Improves Hippocampal Neurogenesis in the Aged Brain and Under Neurodegeneration

Adult hippocampal neurogenesis is altered during aging and under different neuropsychiatric and neurodegenerative diseases. Melatonin shows neurogenic and neuroprotective properties during aging and neuropathological conditions. In this study, we evaluated the effects of chronic treatment with melatonin on different markers of neurodegeneration and hippocampal neurogenesis using immunohistochemistry in the aged and neurodegenerative brains of SAMP8 mice, which is an animal model of accelerated senescence that mimics aging-related Alzheimer’s pathology. Neurodegenerative processes observed in the brains of aged SAMP8 mice at 10 months of age include the presence of damaged neurons, disorganization in the layers of the brain cortex, alterations in neural processes and the length of neuronal prolongations and β-amyloid accumulation in the cortex and hippocampus. This neurodegeneration may be associated with neurogenic responses in the hippocampal dentate gyrus of these mice, since we observed a neurogenic niche of neural stem and progenitor/precursors cells in the hippocampus of SAMP8 mice. However, hippocampal neurogenesis seems to be compromised due to alterations in the cell survival, migration and/or neuronal maturation of neural precursor cells due to the neurodegeneration levels in these mice. Chronic treatment with melatonin for 9 months decreased these neurodegenerative processes and the neurodegeneration-induced neurogenic response. Noticeably, melatonin also induced recovery in the functionality of adult hippocampal neurogenesis in aged SAMP8 mice

p66Shc signaling and autophagy impact on C2C12 myoblast differentiation during senescence

Abstract During aging, muscle regenerative capacities decline, which is concomitant with the loss of satellite cells that enter in a state of irreversible senescence. However, what mechanisms are involved in myogenic senescence and differentiation are largely unknown. Here, we showed that early-passage or “young” C2C12 myoblasts activated the redox-sensitive p66Shc signaling pathway, exhibited a strong antioxidant protection and a bioenergetic profile relying predominantly on OXPHOS, responses that decrease progressively during differentiation. Furthermore, autophagy was increased in myotubes. Otherwise, late-passage or “senescent” myoblasts led to a highly metabolic profile, relying on both OXPHOS and glycolysis, that may be influenced by the loss of SQSTM1/p62 which tightly regulates the metabolic shift from aerobic glycolysis to OXPHOS. Furthermore, during differentiation of late-passage C2C12 cells, both p66Shc signaling and autophagy were impaired and this coincides with reduced myogenic capacity. Our findings recognized that the lack of p66Shc compromises the proliferation and the onset of the differentiation of C2C12 myoblasts. Moreover, the Atg7 silencing favored myoblasts growth, whereas interfered in the viability of differentiated myotubes. Then, our work demonstrates that the p66Shc signaling pathway, which highly influences cellular metabolic status and oxidative environment, is critical for the myogenic commitment and differentiation of C2C12 cells. Our findings also support that autophagy is essential for the metabolic switch observed during the differentiation of C2C12 myoblasts, confirming how its regulation determines cell fate. The regulatory roles of p66Shc and autophagy mechanisms on myogenesis require future attention as possible tools that could predict and measure the aging-related state of frailty and disability