Changes in Body Composition in Anorexia Nervosa: Predictors of Recovery and Treatment Outcome

The restoration of body composition (BC) parameters is considered to be one of the most important goals in the treatment of patients with anorexia nervosa (AN). However, little is known about differences between AN diagnostic subtypes [restricting (AN-R) and binge/purging (AN-BP)] and weekly changes in BC during refeeding treatment. Therefore, the main objectives of our study were twofold: 1) to assess the changes in BC throughout nutritional treatment in an AN sample and 2) to analyze predictors of BC changes during treatment, as well as predictors of treatment outcome. The whole sample comprised 261 participants [118 adult females with AN (70 AN-R vs. 48 AN-BP), and 143 healthy controls]. BC was measured weekly during 15 weeks of day-hospital treatment using bioelectrical impedance analysis (BIA). Assessment measures also included the Eating Disorders Inventory-2, as well as a number of other clinical indices. Overall, the results showed that AN-R and AN-BP patients statistically differed in all BC measures at admission. However, no significant time×group interaction was found for almost all BC parameters. Significant time×group interactions were only found for basal metabolic rate (p = .041) and body mass index (BMI) (p = .035). Multiple regression models showed that the best predictors of pre-post changes in BC parameters (namely fat-free mass, muscular mass, total body water and BMI) were the baseline values of BC parameters. Stepwise predictive logistic regressions showed that only BMI and age were significantly associated with outcome, but not with the percentage of body fat. In conclusion, these data suggest that although AN patients tended to restore all BC parameters during nutritional treatment, only AN-BP patients obtained the same fat mass values as healthy controls. Put succinctly, the best predictors of changes in BC were baseline BC values, which did not, however, seem to influence treatment outcome.     

Agricultural ponds as alternative habitat for waterbirds: spatial and temporal patterns of abundance and management strategies

The progressive lost of natural wetlands as a consequence of human activities has lead to the use of new habitats by the species linked to water presence. In Southeast Spain, thousands of irrigation ponds have been lately constructed to store water for agriculture and are used by waterbirds as an alternative habitat. For this study, breeding and wintering waterbirds were counted in a subset of irrigation ponds between 2002 and 2007. Breeding communities were more abundant than wintering communities, but they presented a similar richness and diversity. The ponds were selected by waterbirds according to their characteristics, and breeding communities were more selective than wintering communities. Our results enhance the importance of pond size (area), connectivity (distance to the nearest wetland) and habitat quality (resource offer and construction material) in the pond selection process. The presence and design of these impoundments could be playing a crucial role for some waterbirds species. Therefore, the long-term information provided here can be useful for establishing management strategies for these artificial wetlands.     

Adenosine thiamine triphosphate accumulates in <Emphasis Type="Italic">Escherichia coli</Emphasis> cells in response to specific conditions of metabolic stress

Background  

E. coli cells are rich in thiamine, most of it in the form of the cofactor thiamine diphosphate (ThDP). Free ThDP is the precursor for two triphosphorylated derivatives, thiamine triphosphate (ThTP) and the newly discovered adenosine thiamine triphosphate (AThTP). While, ThTP accumulation requires oxidation of a carbon source, AThTP slowly accumulates in response to carbon starvation, reaching ~15% of total thiamine. Here, we address the question whether AThTP accumulation in E. coli is triggered by the absence of a carbon source in the medium, the resulting drop in energy charge or other forms of metabolic stress.     

The kinesin of the flagellum attachment zone in Leishmania is required for cell morphogenesis,cell division and virulence in the mammalian host

Leishmania parasites possess a unique and complex cytoskeletal structure termed flagellum attachment zone (FAZ) connecting the base of the flagellum to one side of the flagellar pocket (FP), an invagination of the cell body membrane and the sole site for endocytosis and exocytosis. This structure is involved in FP architecture and cell morphogenesis, but its precise role and molecular composition remain enigmatic. Here, we characterized Leishmania FAZ7, the only known FAZ protein containing a kinesin motor domain, and part of a clade of trypanosomatid-specific kinesins with unknown functions. The two paralogs of FAZ7, FAZ7A and FAZ7B, display different localizations and functions. FAZ7A localizes at the basal body, while FAZ7B localizes at the distal part of the FP, where the FAZ structure is present in Leishmania. While null mutants of FAZ7A displayed normal growth rates, the deletion of FAZ7B impaired cell growth in both promastigotes and amastigotes of Leishmania. The kinesin activity is crucial for its function. Deletion of FAZ7B resulted in altered cell division, cell morphogenesis (including flagellum length), and FP structure and function. Furthermore, knocking out FAZ7B induced a mis-localization of two of the FAZ proteins, and disrupted the molecular organization of the FP collar, affecting the localization of its components. Loss of the kinesin FAZ7B has important consequences in the insect vector and mammalian host by reducing proliferation in the sand fly and pathogenicity in mice. Our findings reveal the pivotal role of the only FAZ kinesin as part of the factors important for a successful life cycle of Leishmania.     

Alteration of oxidative and carbohydrate metabolism under abiotic stress in two rice (Oryza sativa L.) genotypes contrasting in chilling tolerance

Abiotic stress is a major limiting factor in crop production. Physiological comparisons between contrasting abiotic stress-tolerant genotypes will improve understanding of stress-tolerant mechanisms. Rice seedlings (S3 stage) of a chilling-tolerant (CT) genotype (CT6748-8-CA-17) and a chilling-sensitive (CS) genotype (INIAP12) were subjected to abiotic stresses including chilling (13/12 degrees C), salt (100mM NaCl), and osmotic (200mM mannitol). Measures of physiological response to the stresses included changes in stress-related sugars, oxidative products and protective enzymes, parameters that could be used as possible markers for selection of improved tolerant varieties. Metabolite analyses showed that the two genotypes responded differently to different stresses. Genotype survival under chilling-stress was as expected, however, CT was more sensitive to salt stress than the CS genotype. The CT genotype was able to maintain membrane integrity better than CS, perhaps by reduction of lipid peroxidation via increased levels of antioxidant enzymes during chilling stress. This genotype accumulated sugars in response to stress, but the accumulation was usually less than in the CS genotype. Chill-stressed CT accumulated galactose and raffinose whereas these saccharides declined in CS. On the other hand, the tolerance mechanism in the more salt- and water-deficit-tolerant CS may be associated with accumulation of osmoprotectants such as glucose, trehalose and mannitol.     

Membrane-Localized Extra-Large G Proteins and Gβγ of the Heterotrimeric G Proteins Form Functional Complexes Engaged in Plant Immunity in Arabidopsis

In animals, heterotrimeric G proteins, comprising Gα, Gβ, and Gγ subunits, are molecular switches whose function tightly depends on Gα and Gβγ interaction. Intriguingly, in Arabidopsis (Arabidopsis thaliana), multiple defense responses involve Gβγ, but not Gα. We report here that the Gβγ dimer directly partners with extra-large G proteins (XLGs) to mediate plant immunity. Arabidopsis mutants deficient in XLGs, Gβ, and Gγ are similarly compromised in several pathogen defense responses, including disease development and production of reactive oxygen species. Genetic analysis of double, triple, and quadruple mutants confirmed that XLGs and Gβγ functionally interact in the same defense signaling pathways. In addition, mutations in XLG2 suppressed the seedling lethal and cell death phenotypes of BRASSINOSTEROID INSENSITIVE1-associated receptor kinase1-interacting receptor-like kinase1 mutants in an identical way as reported for Arabidopsis Gβ-deficient mutants. Yeast (Saccharomyces cerevisiae) three-hybrid and bimolecular fluorescent complementation assays revealed that XLG2 physically interacts with all three possible Gβγ dimers at the plasma membrane. Phylogenetic analysis indicated a close relationship between XLGs and plant Gα subunits, placing the divergence point at the dawn of land plant evolution. Based on these findings, we conclude that XLGs form functional complexes with Gβγ dimers, although the mechanism of action of these complexes, including activation/deactivation, must be radically different form the one used by the canonical Gα subunit and are not likely to share the same receptors. Accordingly, XLGs expand the repertoire of heterotrimeric G proteins in plants and reveal a higher level of diversity in heterotrimeric G protein signaling.Heterotrimeric GTP-binding proteins (G proteins), classically consisting of Gα, Gβ, and Gγ subunits, are essential signal transduction elements in most eukaryotes. In animals and fungi, ligand perception by G protein-coupled receptors leads to replacement of GDP with GTP in Gα, triggering activation of the heterotrimer (Li et al., 2007; Oldham and Hamm, 2008). Upon activation, GTP-bound Gα and Gβγ are released and interact with downstream effectors, thereby transmitting signals to multiple intracellular signaling cascades. Signaling terminates when the intrinsic GTPase activity of Gα hydrolyzes GTP to GDP and the inactive heterotrimer reforms at the receptor. The large diversity of mammalian Gα subunits confers specificity to the multiple signaling pathways mediated by G proteins (Wettschureck and Offermanns, 2005). Five distinct classes of Gα have been described in animals (Gαi, Gαq, Gαs, Gα12 and Gαv), with orthologs found in evolutionarily primitive organisms such as sponges (Oka et al., 2009). Humans possess four classes of Gα involving 23 functional isoforms encoded by 16 genes (McCudden et al., 2005), while only a single prototypical Gα is usually found per plant genome (Urano et al., 2013). Multiple copies of Gα are present in some species with recently duplicated genomes, such as soybean (Glycine max) with four Gα genes (Blanc and Wolfe, 2004; Bisht et al., 2011). In the model plant Arabidopsis (Arabidopsis thaliana), a prototypical Gα subunit (GPA1) is involved in a number of important processes, including cell proliferation (Ullah et al., 2001), inhibition of inward K⁺ channels and activation of anion channels in guard cells by mediating the abscisic acid pathway (Wang et al., 2001; Coursol et al., 2003), blue light responses (Warpeha et al., 2006, 2007), and germination and postgermination development (Chen et al., 2006; Pandey et al., 2006).It is well established that heterotrimeric G proteins play a fundamental role in plant innate immunity. In Arabidopsis, two different Gβγ dimers (Gβγ1 and Gβγ2) are generally considered to be the predominant elements in G protein defense signaling against a variety of fungal pathogens (Llorente et al., 2005; Trusov et al., 2006, 2007, 2009; Delgado-Cerezo et al., 2012; Torres et al., 2013). By contrast, these studies attributed a small or no role to Gα, because mutants deficient in Gα displayed only slightly increased resistance against the fungal pathogens (Llorente et al., 2005; Trusov et al., 2006; Torres et al., 2013). The Gβγ-mediated signaling also contributes to defense against a model bacterial pathogen Pseudomonas syringae, by participating in programmed cell death (PCD) and inducing reactive oxygen species (ROS) production in response to at least three pathogen-associated molecular patterns (PAMPs; Ishikawa, 2009; Liu et al., 2013; Torres et al., 2013). Gα is not involved in PCD or PAMP-triggered ROS production (Liu et al., 2013; Torres et al., 2013). Nonetheless, Arabidopsis Gα plays a positive role in defense against P. syringae, probably by mediating stomatal function and hence physically restricting bacterial entry to the leaf interior (Zhang et al., 2008; Zeng and He, 2010; Lee et al., 2013). Given the small contribution from Gα, the involvement of heterotrimeric G proteins in Arabidopsis resistance could be explained in two ways: either the Gβγ dimer acts independently from Gα, raising a question of how is it activated upon a pathogen attack, or Gα is replaced by another protein for heterotrimer formation.The Arabidopsis genome contains at least three genes encoding Gα-like proteins that have been classified as extra-large G proteins (XLGs; Lee and Assmann, 1999; Ding et al., 2008). XLGs comprise two structurally distinct regions. The C-terminal region is similar to the canonical Gα, containing the conserved helical and GTPase domains, while the N-terminal region is a stretch of approximately 400 amino acids including a putative nuclear localization signal (Ding et al., 2008). GTP binding and hydrolysis were confirmed for all three XLG proteins, although their enzymatic activities are very slow and require Ca²⁺ as a cofactor, whereas canonical Gα utilizes Mg²⁺ (Heo et al., 2012). Several other features differentiate XLGs from Gα subunits. Comparative analysis of XLG1 and Gα at the DNA level showed that the genes are organized in seven and 13 exons, respectively, without common splicing sites (Lee and Assmann, 1999). XLGs have been reported to localize to the nucleus (Ding et al., 2008). Analysis of knockout mutants revealed a nuclear function for XLG2, as it physically interacts with the Related To Vernalization1 (RTV1) protein, enhancing the DNA binding activity of RTV1 to floral integrator gene promoters and resulting in flowering initiation (Heo et al., 2012). Therefore, it appears that XLGs may act independently of G protein signaling. On the other hand, functional similarities between XLGs and the Arabidopsis Gβ subunit (AGB1) were also discovered. For instance, XLG3- and Gβ-deficient mutants were similarly impaired in root gravitropic responses (Pandey et al., 2008). Knockout of all three XLG genes caused increased root length, similarly to the Gβ-deficient mutant (Ding et al., 2008). Furthermore, as observed in Gβ-deficient mutants, xlg2 mutants displayed increased susceptibility to P. syringae, indicating a role in plant defense (Zhu et al., 2009). Nevertheless, a genetic analysis of the possible functional interaction between XLGs and Gβ has not been established.In this report, we performed in-depth genetic analyses to test the functional interaction between the three XLGs and Gβγ dimers during defense-related responses in Arabidopsis. We also examined physical interaction between XLG2 and the Gβγ dimers using yeast (Saccharomyces cerevisiae) three-hybrid (Y3H) and bimolecular fluorescent complementation (BiFC) assays. Our findings indicate that XLGs function as direct partners of Gβγ dimers in plant defense signaling. To estimate relatedness of XLGs and Gα proteins, we carried out a phylogenetic analysis. Based on our findings, we conclude that plant XLG proteins most probably originated from a canonical Gα subunit and retained prototypical interaction with Gβγ dimers. They function together with Gβγ in a number of processes including plant defense, although they most probably evolved activation/deactivation mechanisms very different from those of a prototypical Gα.