Nitrogen fixation in a landrace of maize is supported by a mucilage-associated diazotrophic microbiota

© 2018 Van Deynze et al. http://creativecommons.org/licenses/by/4.0/. Plants are associated with a complex microbiota that contributes to nutrient acquisition, plant growth, and plant defense. Nitrogen-fixing microbial associations are efficient and well characterized in legumes but are limited in cereals, including maize. We studied an indigenous landrace of maize grown in nitrogen-depleted soils in the Sierra Mixe region of Oaxaca, Mexico. This landrace is characterized by the extensive development of aerial roots that secrete a carbohydrate-rich mucilage. Analysis of the mucilage microbiota indicated that it was enriched in taxa for which many known species are diazotrophic, was enriched for homologs of genes encoding nitrogenase subunits, and harbored active nitrogenase activity as assessed by acetylene reduction and 15 N 2 incorporation assays. Field experiments in Sierra Mixe using 15 N natural abundance or 15 N-enrichment assessments over 5 years indicated that atmospheric nitrogen fixation contributed 29%–82% of the nitrogen nutrition of Sierra Mixe maize

Multiple Promoters and Alternative Splicing: Hoxa5 Transcriptional Complexity in the Mouse Embryo

The genomic organization of Hox clusters is fundamental for the precise spatio-temporal regulation and the function of each Hox gene, and hence for correct embryo patterning. Multiple overlapping transcriptional units exist at the Hoxa5 locus reflecting the complexity of Hox clustering: a major form of 1.8 kb corresponding to the two characterized exons of the gene and polyadenylated RNA species of 5.0, 9.5 and 11.0 kb. This transcriptional intricacy raises the question of the involvement of the larger transcripts in Hox function and regulation.We have undertaken the molecular characterization of the Hoxa5 larger transcripts. They initiate from two highly conserved distal promoters, one corresponding to the putative Hoxa6 promoter, and a second located nearby Hoxa7. Alternative splicing is also involved in the generation of the different transcripts. No functional polyadenylation sequence was found at the Hoxa6 locus and all larger transcripts use the polyadenylation site of the Hoxa5 gene. Some larger transcripts are potential Hoxa6/Hoxa5 bicistronic units. However, even though all transcripts could produce the genuine 270 a.a. HOXA5 protein, only the 1.8 kb form is translated into the protein, indicative of its essential role in Hoxa5 gene function. The Hoxa6 mutation disrupts the larger transcripts without major phenotypic impact on axial specification in their expression domain. However, Hoxa5-like skeletal anomalies are observed in Hoxa6 mutants and these defects can be explained by the loss of expression of the 1.8 kb transcript. Our data raise the possibility that the larger transcripts may be involved in Hoxa5 gene regulation.Our observation that the Hoxa5 larger transcripts possess a developmentally-regulated expression combined to the increasing sum of data on the role of long noncoding RNAs in transcriptional regulation suggest that the Hoxa5 larger transcripts may participate in the control of Hox gene expression

Validation of a social cohesion theoretical framework: a multiple group SEM strategy

Social cohesion dates back to the end of the nineteenth century. Back then, society experienced epochal transformations, as are also happening nowadays. Whenever there are epochal changes, a social order (cohesion) matter arises. The paper provides a conceptual scheme of social cohesion identifying its constituent dimensions subdivided by three spheres (macro, meso, micro) and two perspectives (objective and subjective). The overarching aim is to test the validity of the operationalization of the social cohesion model provided. Firstly, we conducted an exploratory factor analysis introducing an approach implemented in Mplus named exploratory structural equation modeling that shows several useful characteristics. Afterward, through a structural equation modeling approach, we performed several confirmatory factor analyses adopting a multiple group SEM strategy in order to cross-validate the social cohesion model

A Multilevel Measurement Model of Social Cohesion

In spite of its currency both in academic research and political rhetoric, there are numerous attempts to define and conceptualize the social cohesion concept but there has been paid little attention to provide a rigorous and empirically tested definition. There are even fewer studies that address social cohesion in a framework of cross-cultural validation of the indicators testing the equivalence of the factorial structure across countries. Finally, as far as we know there is no study that attempt to provide an empirically tested multilevel definition of social cohesion specifying a Multilevel Structural Equation Model. This study aims to cover this gap. First, we provide a theoretical construct of social cohesion taking into account not only its multidimensionality but also its multilevel structure. In the second step, to test the validity of this theoretical construct, we perform a multilevel confirmatory factor analysis in order to verify if the conceptual structure suggested in first step holds. In addition, we test the cross-level structural equivalence and the measurement invariance of the model in order to verify if the same multilevel model of social cohesion holds across the 29 countries analysed. In the final step, we specify a second-order multilevel CFA model in order to identify the existence of a general factor that can be called “social cohesion” operating in society that accounts for the surface phenomena that we observe

Leave the Drama on the Stage: The Effect of Cultural Participation on Health

The aim of this study is to estimate the causal effect of cultural participation on health status. Cultural activities may directly impact upon health through palliative coping or substituting health-compromising behaviors. Cultural engagement may also facilitate the development of social networks, which can improve health via social support and the dissemination of social health norms. Previous estimates on the arts-health relationship are potentially biased due to reverse causality and unobserved heterogeneity. Using individual-level data from Germany, we employ propensity-score matching methods. The treatment group is confined to individuals that visit cultural events at least once a month. The participation equation includes a rich set of personal characteristics that cover the respondents' demographic and social background, social capital and leisure-time activities, health-related lifestyle, personality and childhood environment. We explicitly consider reverse causality by including the pre-treatment trends in health outcomes among the covariates. To deal with time-fixed unobserved heterogeneity, we combine the matching model with a difference-indifference approach. We find that frequent cultural-event visits are unrelated to health once we account for unobserved persistent differences across individuals. However, examining the dose-response relationship we find positive mental-health effects of low levels of cultural participation compared to non-attendance. Our results may thus yield important insights on the effectiveness of arts participation as a means to reduce social inequalities in health

Tauopathic Changes in the Striatum of A53T α-Synuclein Mutant Mouse Model of Parkinson's Disease

Tauopathic pathways lead to degenerative changes in Alzheimer's disease and there is evidence that they are also involved in the neurodegenerative pathology of Parkinson's disease [PD]. We have examined tauopathic changes in striatum of the α-synuclein (α-Syn) A53T mutant mouse. Elevated levels of α-Syn were observed in striatum of the adult A53T α-Syn mice. This was accompanied by increases in hyperphosphorylated Tau [p-Tau], phosphorylated at Ser202, Ser262 and Ser396/404, which are the same toxic sites also seen in Alzheimer's disease. There was an increase in active p-GSK-3β, hyperphosphorylated at Tyr216, a major and primary kinase known to phosphorylate Tau at multiple sites. The sites of hyperphosphorylation of Tau in the A53T mutant mice were similar to those seen in post-mortem striata from PD patients, attesting to their pathophysiological relevance. Increases in p-Tau were not due to alterations on protein phosphatases in either A53T mice or in human PD, suggesting lack of involvement of these proteins in tauopathy. Extraction of striata with Triton X-100 showed large increases in oligomeric forms of α-Syn suggesting that α-Syn had formed aggregates the mutant mice. In addition, increased levels of p-GSK-3β and pSer396/404 were also found associated with aggregated α-Syn. Differential solubilization to measure protein binding to cytoskeletal proteins demonstrated that p-Tau in the A53T mutant mouse were unbound to cytoskeletal proteins, consistent with dissociation of p-Tau from the microtubules upon hyperphosphorylation. Interestingly, α-Syn remained tightly bound to the cytoskeleton, while p-GSK-3β was seen in the cytoskeleton-free fractions. Immunohistochemical studies showed that α-Syn, pSer396/404 Tau and p-GSK-3β co-localized with one another and was aggregated and accumulated into large inclusion bodies, leading to cell death of Substantia nigral neurons. Together, these data demonstrate an elevated state of tauopathy in striata of the A53T α-Syn mutant mice, suggesting that tauopathy is a common feature of synucleinopathies

The BMP Antagonist Follistatin-Like 1 Is Required for Skeletal and Lung Organogenesis

Follistatin-like 1 (Fstl1) is a secreted protein of the BMP inhibitor class. During development, expression of Fstl1 is already found in cleavage stage embryos and becomes gradually restricted to mesenchymal elements of most organs during subsequent development. Knock down experiments in chicken and zebrafish demonstrated a role as a BMP antagonist in early development. To investigate the role of Fstl1 during mouse development, a conditional Fstl1 KO allele as well as a Fstl1-GFP reporter mouse were created. KO mice die at birth from respiratory distress and show multiple defects in lung development. Also, skeletal development is affected. Endochondral bone development, limb patterning as well as patterning of the axial skeleton are perturbed in the absence of Fstl1. Taken together, these observations show that Fstl1 is a crucial regulator in BMP signalling during mouse development

Homeotic transformations reflect departure from the mammalian 'rule of seven' cervical vertebrae in sloths: inferences on the Hox code and morphological modularity of the mammalian neck

Background: Sloths are one of only two exceptions to the mammalian 'rule of seven' vertebrae in the neck. As a striking case of breaking the evolutionary constraint, the explanation for the exceptional number of cervical vertebrae in sloths is still under debate. Two diverging hypotheses, both ultimately linked to the low metabolic rate of sloths, have been proposed: hypothesis 1 involves morphological transformation of vertebrae due to changes in the Hox gene expression pattern and hypothesis 2 assumes that the Hox gene expression pattern is not altered and the identity of the vertebrae is not changed. Direct evidence supporting either hypothesis would involve knowledge of the vertebral Hox code in sloths, but the realization of such studies is extremely limited. Here, on the basis of the previously established correlation between anterior Hox gene expression and the quantifiable vertebral shape, we present the morphological regionalization of the neck in three different species of sloths with aberrant cervical count providing indirect insight into the vertebral Hox code. Results: Shape differences within the cervical vertebral column suggest a mouse-like Hox code in the neck of sloths. We infer an anterior shift of HoxC-6 expression in association with the first thoracic vertebra in short-necked sloths with decreased cervical count, and a posterior shift of HoxC-5 and HoxC-6 expression in long-necked sloths with increased cervical count. Conclusion: Although only future developmental analyses in non-model organisms, such as sloths, will yield direct evidence for the evolutionary mechanism responsible for the aberrant number of cervical vertebrae, our observations lend support to hypothesis 1 indicating that the number of modules is retained but their boundaries are displaced. Our approach based on quantified morphological differences also provides a reliable basis for further research including fossil taxa such as extinct 'ground sloths' in order to trace the pattern and the underlying genetic mechanisms in the evolution of the vertebral column in mammals