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14. Sequential extraction and analysis of cell wall polysaccharides from Inula viscosa leaves and stems.

Author

Anouche, Rayen, Bouhafsoun, Aicha, Frey, Carlos, and Acebes, José Luis

Subjects
POLYSACCHARIDES, SEQUENTIAL analysis, MOLECULAR weights, CELL analysis, XYLANS, HEMICELLULOSE, INULIN
Abstract

Inula viscosa (syn Dittrichia viscosa) (sticky fleabane) from the Asteraceae family, is well-known for its pharmacological activities. In this research, anatomical characterization of leaves and stems of Inula viscosa plants revealed a considerable heterogeneity in their cell walls. Cell walls were isolated separately from leaves and stems and subjected to sequential extractions with boiling water, oxalate ammonium, KOH and NaOH solutions. The four polysaccharide fractions obtained were comparatively analysed using gas chromatography-flame ionization detector (GC-FID) and Fourier Transform Infrared–Attenuated Total Reflectance (ATR-FTIR) spectroscopy. The findings showed that the polysaccharides were unevenly distributed in the two organs. ATR-FTIR data reflected a higher proportion of pectins in stems relative to leaves in both fractions. Pectic fractions (hot water soluble and oxalate soluble fractions) seemed to be mainly composed by homogalacturonan and rhamnogalacturonan, with a residual presence of inulin. Hemicellulose (KOH and NaOH) fractions, instead, were rich in xylans, and still contained a low proportion of pectic polysaccharides. ATR-FTIR data pointed to a higher proportion of xylans in stems than in leaves. Finally, attending the molecular mass of cell wall polysaccharides from leaves, pectin fractions showed the presence of populations of polysaccharides with lower molecular masses than those of hemicellulose fractions. [ABSTRACT FROM AUTHOR]

Published
2022
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23. Histological description of Saxifraga paniculata leaves with special focus on structures that release CaCO3.

Author

Michavila, Santiago, Encina, Antonio, Frey, Carlos, and Álvarez, Rafael

Subjects
LEAF anatomy, SUCCULENT plants, TRACHEARY cells, CALCIUM carbonate, SCANNING electron microscopy
Abstract

Saxifraga paniculata is a subalpine succulent perennial plant arranged in a rosette that is usually found in shallow soil among limestone rocks. Stereoscopic, light and scanning electron microscopy were used to describe the anatomical structure of S. paniculata leaves, paying special attention to structures related to CaCO3 (calcium carbonate) release. Anomocytic stomata are unevenly distributed on each leaf face, being absent in the lower third. The basal leaf margin presents translucent pluricellular trichomes of variable length and width. Towards the apical margin, trichomes become teeth. Both trichomes and teeth are completely covered with whitish CaCO3 crystals. Each tooth has a circular cavity connected to a single hydathode through pores. Clearing treatment revealed camptodromous leaf venation. Anatomical structure shows a bifacial cross-section with spongy mesophyll cells at basal part, becoming heterogeneous at the apex with palisade mesophyll on the adaxial face. Hydathodes are epithematic and connected to outer cavities via two kidney-shaped guard cells showing large substomatal cavity. The epithem is surrounded by a thickened sheath and is formed of highly packed elongated cells with interspersed tracheary elements. CaCO3 deposits consist of microscopic crystals with varying geometries, of which the rhombus is the basic unit. [ABSTRACT FROM AUTHOR]

Published
2022
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26. Managing the Exit from Fixed Exchange Rate Regimes: Partisan and Coalitional Explanations for the Divergent Paths of Brazil and Argentina.

Author

Freytes Frey, Carlos

Subjects
*FOREIGN exchange rates, *MACROECONOMICS, *ECONOMIC policy, *INTERNATIONAL alliances, *PARTISANSHIP
Abstract

What explains Argentina’s and Brazil’s paths out of fixed exchange regimes at the turn of the century? Both countries faced similar imbalances in the late ‘90s. While Argentina adjusted in 2001 by financial crash, Brazil was able to transit more orderly toward a flexible exchange rate regime in 1999. My argument is that successful transitions toward a new set of macroeconomic institutions requires incumbents to craft a political coalition able to control the relevant institutional veto players. The paper explains incumbents’ capacity for crafting these coalitions by focusing on partisan dynamics within federal institutions. Based on the case studies, I challenge the conventional wisdom on the role of nationally integrated parties in overcoming perverse fiscal incentives in federations. In presidential systems with divided government, the fragmentation of the party system may contribute to governance by multiplying the number of potential legislative partners the executive can choose. On the other hand, when the national executive faces only few nationally integrated opposition parties, the costs of coalition building and the probability of legislative deadlock increase. Brazil and Argentina illustrate each one of these patterns. ..PAT.-Unpublished Manuscript [ABSTRACT FROM AUTHOR]

Published
2009

28. Histological description of Saxifraga paniculata leaves with special focus on structures that release CaCO3.

Author

Michavila, Santiago, Encina, Antonio, Frey, Carlos, and Álvarez, Rafael

Subjects
*LEAF anatomy, *SUCCULENT plants, *TRACHEARY cells, *CALCIUM carbonate, *SCANNING electron microscopy
Abstract

Saxifraga paniculata is a subalpine succulent perennial plant arranged in a rosette that is usually found in shallow soil among limestone rocks. Stereoscopic, light and scanning electron microscopy were used to describe the anatomical structure of S. paniculata leaves, paying special attention to structures related to CaCO3 (calcium carbonate) release. Anomocytic stomata are unevenly distributed on each leaf face, being absent in the lower third. The basal leaf margin presents translucent pluricellular trichomes of variable length and width. Towards the apical margin, trichomes become teeth. Both trichomes and teeth are completely covered with whitish CaCO3 crystals. Each tooth has a circular cavity connected to a single hydathode through pores. Clearing treatment revealed camptodromous leaf venation. Anatomical structure shows a bifacial cross-section with spongy mesophyll cells at basal part, becoming heterogeneous at the apex with palisade mesophyll on the adaxial face. Hydathodes are epithematic and connected to outer cavities via two kidney-shaped guard cells showing large substomatal cavity. The epithem is surrounded by a thickened sheath and is formed of highly packed elongated cells with interspersed tracheary elements. CaCO3 deposits consist of microscopic crystals with varying geometries, of which the rhombus is the basic unit. [ABSTRACT FROM AUTHOR]

Published
2022
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29. Immunohistochemical dynamics of cell wall matrix polymers during tomato autograft healing

Author

Fisiologia Vegetal, Frey, Carlos, Martínez Romera, Nerea, Encina García, Antonio Esteban, Acebes Arranz, José Luis, Fisiologia Vegetal, Frey, Carlos, Martínez Romera, Nerea, Encina García, Antonio Esteban, and Acebes Arranz, José Luis

Abstract

[EN] A large part of the production of tomato plants is grafted. Although it has recently been described that cell walls play an important role in tomato graft healing, the spatiotemporal dynamics of cell wall changes in this critical process remains largely unknown. The aim of this work was to immunolocalize changes in the major cell wall matrix components of autograft union tissues throughout the course of healing, from 1 to 20 days after grafting (DAG). Homogalacturonan was de novo synthetized and deposited in the cut edges, displaying the low methyl-esterified homogalacturonan a stronger labelling. Labelling of galactan side chains of rhamnogalacturonan increased until 8 DAG, although remarkably a set of cells at the graft union did not show labelling for this epitope. Changes in xylan immunolocalization were associated to the xylem vasculature development throughout, while those of xyloglucan revealed early synthesis at the cut edges. Arabinogalactan proteins increased up to 8 DAG and showed scion-rootstock asymmetry, with a higher extent in the scion. The combination of these changes appears to be related with the success of the autograft, specifically facilitating the adhesion phase between scion-rootstock tissues. This knowledge paves the way for improved grafting using methods that facilitate appropriate changes in the time and space dynamics of these cell wall compounds.

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