Association between Fractional Oxygen Extraction from Resting Quadriceps Muscle and Body Composition in Healthy Men

[EN] This study aimed to associate body composition with fractional oxygen extraction at rest in healthy adult men. Fourteen healthy adults (26.93 ± 2.49 years) from Chile participated. Body composition was assessed with octopole bioimpedance, and resting muscle oxygenation was evaluated in the vastus lateralis quadriceps with near-infrared spectroscopy (NIRS) during a vascular occlusion test, analyzing the muscleVO2, resaturation velocity during reactive hyperemia via the muscle saturation index (%TSI), and the area above the curve of HHb (AACrep). It was observed that the total and segmented fat mass are associated with lower reoxygenation velocities during hyperemia (p = 0.008; β = 0.678: p = 0.002; β = 0.751), and that the total and segmented skeletal muscle mass are associated with higher reoxygenation velocities during hyperemia (p = 0.020; β = −0.614: p = 0.027; β = −0.587). It was also observed that the total and segmented fat mass were associated with a higher area above the curve of HHb (AACrep) during hyperemia (p = 0.007; β = 0.692: p = 0.037; β = 0.564), and that total and segmented skeletal muscle mass was associated with a lower area above the curve of HHb (AACrep) during hyperemia (p = 0.007; β = −0.703: p = 0.017; β = −0.632). We concluded that fat mass is associated with lower resaturation rates and lower resting fractional O2 extraction levels. In contrast, skeletal muscle mass is associated with higher resaturation rates and fractional O2 extraction during reactive hyperemia. The AACrep may be relevant in the evaluation of vascular adaptations to exercise and metabolic health.S

Boron deficiency in the legume-rhizobia interaction:Symbiosis or pathogenesis?

The rhizobia-legume symbiosis is driven by cell and molecular plant-microbe interactions that must work very accurately to avoid triggering of host plant defense reactions. Failure in cell or molecular components implicated in the interaction often results in pathogenic rather than symbiotic responses. Boron (B), a micronutrient essential for plant growth, seems to modulate signaling during nodule development. Boron deficiency alters early preinfection and invasion events, turning incompatible the interaction between the legume and its host rhizobio, and some plant defense mechanisms, including morphological barriers and synthesis of pathogenesis-related (PR) proteins take place

Effects of B deficiency on legume nodule organogenesis. Is boron involved in signalling during cell cycle regulation?

The main objective of this work was to analyze the effect of boron (B) deficiency on nodule organogenesis. Boron is an essential micronutrient for plants and for the Rhizobium-legume symbiosis development. Boron deficiency has a strong effect on components involved in plant-bacteria molecular and cell interactions during the development of the legume-rhizobia symbiosis. Because nodule organogenesis is driven by rhizobia-legume interactions, the effect of B deficiency on cell cycle regulation during nodule development was studied in Pisum sativum and Medicago sativa plants

Effects of B deficiency on legume nodule organogenesis. Is boron involved in signalling during cell cycle regulation?

The main objective of this work was to analyze the effect of boron (B) deficiency on nodule organogenesis. Boron is an essential micronutrient for plants and for the Rhizobium-legume symbiosis development. Boron deficiency has a strong effect on components involved in plant-bacteria molecular and cell interactions during the development of the legume-rhizobia symbiosis. Because nodule organogenesis is driven by rhizobia-legume interactions, the effect of B deficiency on cell cycle regulation during nodule development was studied in Pisum sativum and Medicago sativa plants

Introduction to mineral nutrition plants

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Ligands of boron in Pisum sativum nodules are involved in regulation of oxygen concentration and rhizobial infection

16 Pags., 7 Figs. The definitive version is available at: http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-3040Boron (B) is an essential nutrient for N(2)-fixing legume-rhizobia symbioses, and the capacity of borate ions to bind and stabilize biomolecules is the basis of any B function. We used a borate-binding-specific resin and immunostaining techniques to identify B ligands important for the development of Pisum sativum- Rhizobium leguminosarum 3841 symbiotic nodules. arabinogalactan-extensin (AGPE), recognized by MAC 265 antibody, appeared heavily bound to the resin in extracts derived from B-sufficient, but not from Bdeficient nodules. MAC 265 stained the infection threads and the extracellular matrix of cortical cells involved in the oxygen diffusion barrier. In B-deprived nodules, immunolocalization of MAC 265 antigens was significantly reduced. Leghaemoglobin (Lb) concentration largely decreased in B-deficient nodules. The absence of MAC 203 antigens in B-deficient nodules suggests a high internal oxygen concentration, as this antibody detects an epitope on the lipopolysaccharide (LPS) of bacteroids typically expressed in microaerobically grown R. leguminosarum 3841. However, B-deprived nodules did not accumulate oxidized lipids and proteins, and revealed a decrease in the activity of the major antioxidant enzyme ascorbate peroxidase (APX). Therefore, B deficiency reduced the stability of nodule macromolecules important for rhizobial infection, and for regulation of oxygen concentration, resulting in non-functional nodules, but did not appear to induce oxidative damage in low-B nodules.This work was supported by Ministerio de Educación y Ciencia, BIO2008-05736-CO2-01 and by MICROAMBIENTECM Program from Comunidad de Madrid. M.R. is the recipient of a contract from Comunidad de Madrid.Peer reviewe