Browsing by Author "Vega, Andrea"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Effect of pollination and fertilization on the expression of genes related to floral transition, hormone synthesis and berry development in grapevine
    (ELSEVIER GMBH, 2011) Dauelsberg, Patricia; Tomas Matus, Jose; Josefina Poupin, Maria; Leiva Ampuero, Andres; Godoy, Francisca; Vega, Andrea; Arce Johnson, Patricio
    In the present work, the effect of assisted fertilization on anatomical, morphological and gene expression changes occurring in carpels and during early stages of berry development in Vitis vinifera were studied. Inflorescences were emasculated before capfall, immediately manually pollinated (EP) and fruit development was compared to emasculated but non-pollinated (ENP) and self-pollinated inflorescences (NESP). The diameter of berries derived from pollinated flowers (EP and NESP) was significantly higher than from non-pollinated flowers (ENP) at 21 days after emasculation/pollination (DAE), and a rapid increase in the size of the inner mesocarp, together with the presence of an embryo-like structure, were observed. The expression of gibberellin oxidases (GA200x and GA2ox), anthranilate synthase (related to auxin synthesis) and cytokinin synthase coding genes was studied to assess the relationship between hormone synthesis and early berry development, while flower patterning genes were analyzed to describe floral transition. Significant expression changes were found for hormone-related genes, suggesting that their expression at early stages of berry development (13 DAE) is related to cell division and differentiation of mesocarp tissue at a later stage (21 DAE). Expression of hormone-related genes also correlates with the expression of VvHB13, a gene related to mesocarp expansion, and with an increased repression of floral patterning genes (PISTILLATA and TM6), which may contribute to prevent floral transition inhibiting fruit growth before fertilization takes place. (C) 2011 Elsevier GmbH. All rights reserved.
  • Thumbnail Image
    Item
    Laparoscopic Roux-en-Y gastric bypass versus laparoscopic sleeve gastrectomy: a case-control study and 3 years of follow-up
    (ELSEVIER SCIENCE INC, 2012) Boza, Camilo; Gamboa, Cristian; Salinas, Jose; Achurra, Pablo; Vega, Andrea; Perez, Gustavo
    Background: Laparoscopic sleeve gastrectomy (LSG) has become a popular surgical procedure among bariatric surgeons. Few studies have compared the efficacy of the procedure to laparoscopic Roux-en-Y gastric bypass (LRYGB). We performed a case-control study to assess the surgical results, weight progression, and remission of co-morbid conditions.
  • No Thumbnail Available
    Item
    Nitrate Induction of Primary Root Growth Requires Cytokinin Signaling in Arabidopsis thaliana
    (2020) Naulin Gysling, Pamela Alejandra; Armijo, Grace; Vega, Andrea; Tamayo Godoy, Karem Patricia; Gras, Diana; de la Cruz, Javiera; Gutiérrez Ilabaca, Rodrigo Antonio
    Nitrate can act as a potent signal to control growth and development in plants. In this study, we show that nitrate is able to stimulate primary root growth via increased meristem activity and cytokinin signaling. Cytokinin perception and biosynthesis mutants displayed shorter roots as compared with wild-type plants when grown with nitrate as the only nitrogen source. Histological analysis of the root tip revealed decreased cell division and elongation in the cytokinin receptor double mutant ahk2/ahk4 as compared with wild-type plants under a sufficient nitrate regime. Interestingly, a nitrate-dependent root growth arrest was observed between days 5 and 6 after sowing. Wild-type plants were able to recover from this growth arrest, while cytokinin signaling or biosynthesis mutants were not. Transcriptome analysis revealed significant changes in gene expression after, but not before, this transition in contrasting genotypes and nitrate regimes. We identified genes involved in both cell division and elongation as potentially important for primary root growth in response to nitrate. Our results provide evidence linking nitrate and cytokinin signaling for the control of primary root growth in Arabidopsis thaliana.
  • Thumbnail Image
    Item
    Phytoplasma and virus detection in commercial plantings of Vitis vinifera cv. Merlot exhibiting premature berry dehydration
    (UNIV CATOLICA DE VALPARAISO, 2008) Matus, Jose Tomas; Vega, Andrea; Loyola, Rodrigo; Serrano, Carolina; Cabrera, Soledad; Arce Johnson, Patricio
    A new and devastating physiological disorder of Vitis vinifera cv. Merlot was recently reported, known as premature berry dehydration (PBD), which is characterized by plant growth reduction, induction of general senescence and pedicel necrosis in the fruit, causing significant reductions in vineyard production. The causes of this disease remain unclear and previous reports suggest that it may be associated with phloem disruption and water provision. For this reason, any factor causing phloem disturbances could cause an important change in the berry water status. As some micro-organisms have been reported to disrupt phloem flow, we analyzed the occurrence of phytoplasma and viruses in commercial vineyards presenting PBD. In this study, a phytoplasma was detected by electron microscopy and nested PCR while virus infections were diagnosed by RT-PCR in samples collected during two growing seasons. The presence of phytoplasma only in samples from grape plants with PBD suggests that this pathogen may be one of the causal agents of this disorder. We suggest that the influence of other factors, such as virus infections, agronomic handling and environmental conditions also modulate berry dehydration. This is the first study at the microscopic and molecular levels that correlates phytoplasma presence with PBD.
  • Thumbnail Image
    Item
    Post-veraison sunlight exposure induces MYB-mediated transcriptional regulation of anthocyanin and flavonol synthesis in berry skins of Vitis vinifera
    (OXFORD UNIV PRESS, 2009) Thomas Matus, Jose; Loyola, Rodrigo; Vega, Andrea; Pena Neira, Alvaro; Bordeu, Edmundo; Arce Johnson, Patricio; Antonio Alcalde, Jose
    Anthocyanins, flavan-3-ols, and flavonols are the three major classes of flavonoid compounds found in grape berry tissues. Several viticultural practices increase flavonoid content in the fruit, but the underlying genetic mechanisms responsible for these changes have not been completely deciphered. The impact of post-veraison sunlight exposure on anthocyanin and flavonol accumulation in grape berry skin and its relation to the expression of different transcriptional regulators known to be involved in flavonoid synthesis was studied. Treatments consisting of removing or moving aside the basal leaves which shade berry clusters were applied. Shading did not affect sugar accumulation or gene expression of HEXOSE TRANSPORTER 1, although in the leaf removal treatment, these events were retarded during the first weeks of ripening. Flavonols were the most drastically reduced flavonoids following shading and leaf removal treatments, related to the reduced expression of FLAVONOL SYNTHASE 4 and its putative transcriptional regulator MYB12. Anthocyanin accumulation and the expression of CHS2, LDOX, OMT, UFGT, MYBA1, and MYB5a genes were also affected. Other regulatory genes were less affected or not affected at all by these treatments. Non-transcriptional control mechanisms for flavonoid synthesis are also suggested, especially during the initial stages of ripening. Although berries from the leaf removal treatment received more light than shaded fruits, malvidin-3-glucoside and total flavonol content was reduced compared with the treatment without leaf removal. This work reveals that flavonol-related gene expression responds rapidly to field changes in light levels, as shown by the treatment in which shaded fruits were exposed to light in the late stages of ripening. Taken together, this study establishes MYB-specific responsiveness for the effect of sun exposure and sugar transport on flavonoid synthesis.
  • Thumbnail Image
    Item
    The Calcium Ion Is a Second Messenger in the Nitrate Signaling Pathway of Arabidopsis thaliana
    (2015) Riveras Hernández, Eleodoro Javier; Álvarez, José M.; Vidal, Elena A.; Oses, Carolina; Vega, Andrea; Gutiérrez Ilabaca, Rodrigo Antonio
  • Thumbnail Image
    Item
    Transcriptome analysis reveals regulatory networks underlying differential susceptibility to Botrytis cinerea in response to nitrogen availability in Solanum lycopersicum
    (2015) Vega, Andrea; Canessa, Paulo; Hoppe, Gustavo; Retamal, Ignacio; Moyano, Tomás C.; Canales, Javier; Gutiérrez Ilabaca, Rodrigo Antonio; Rubilar, Joselyn