Performance/mathematics: a dramatisation of mathematical methods

This essay conceptualises the notion of performance mathematics in terms of a paradoxical relationship with the constructed notion of truth, which is shared by theatrical and mathematical performance. Specifically, I argue that these two disciplines can and cannot be reconciled with truthfulness. Grounding my comparison on the notion of an axiomatic method common to both disciplines, I argue that theatrical and mathematical performance can speak of truths only when these truths are properly staged or methodologically grounded according to the internal rules and conditions laid out by each discipline. But in the same way that these truths can be constructed, or they can be done, so they can be undone. Arguing that mathematics can be described as a performance of specific outcomes involving abstract objects and functions, I trace a cross-disciplinary comparative analysis of performance elements (especially axioms and functions), drawing on a number of theatre and mathematical theories. Some suggestions are also put forward in terms of the connection between the performance of mathematised texts and computational mathematics, particularly in terms of an inherent poetics and theatricality inside the performance-oriented, mathematised languages of digital computing

Fécondation chez les plantes à fleurs (étude de mutants affectés dans les étapes d'interaction des gamétophytes)

LYON-ENS Sciences (693872304) / SudocSudocFranceF

BeerDeCoded: the open beer metagenome project [version 2; referees: 1 approved, 2 approved with reservations]

Next generation sequencing has radically changed research in the life sciences, in both academic and corporate laboratories. The potential impact is tremendous, yet a majority of citizens have little or no understanding of the technological and ethical aspects of this widespread adoption. We designed BeerDeCoded as a pretext to discuss the societal issues related to genomic and metagenomic data with fellow citizens, while advancing scientific knowledge of the most popular beverage of all. In the spirit of citizen science, sample collection and DNA extraction were carried out with the participation of non-scientists in the community laboratory of Hackuarium, a not-for-profit organisation that supports unconventional research and promotes the public understanding of science. The dataset presented herein contains the targeted metagenomic profile of 39 bottled beers from 5 countries, based on internal transcribed spacer (ITS) sequencing of fungal species. A preliminary analysis reveals the presence of a large diversity of wild yeast species in commercial brews. With this project, we demonstrate that coupling simple laboratory procedures that can be carried out in a non-professional environment with state-of-the-art sequencing technologies and targeted metagenomic analyses, can lead to the detection and identification of the microbial content in bottled beer

PPARβ is essential for <i>X. laevis</i> development.

<p>(A) Design of the morpholino (PPARβ MO) to target PPARβ translation and of the control morpholino (Co). Capital letters designate nucleotides that can hybridize with the PPARβ MO. (B) Immunoblot showing endogenous PPARβ levels in non-injected embryos (Ni) and embryos injected with PPARβ MO or Co. β-actin served as a loading control. (C) Scoring of A–P axis defects. Different doses of PPARβ MO, Co, or a combination of PPARβ MO and PPARβ_rescue mRNA were injected. Embryos with a length about a third of that of non-injected sibling embryos were scored as ‘very-short axis’, and those with a length of about two thirds of normal were scored as ‘short axis’. (D) Representative not-injected (Ni), Co-injected (Co), MO-injected (MO), and MO combined with rescue injected (PPARβ MO + PPARβ_rescue) embryos.</p

Rate of transcript level variation is maximal at gastrula stage.

<p>(A) Data from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083300#pone.0083300-Irie1" target="_blank">[23]</a> were used to quantify transcription variations during normal development. The number of genes showing an RNA level increase or decrease by 2×, 4×, or 8× between two consecutive stages was plotted. Data were normalized by the duration, in hours, of each developmental period analysed. (B) The group of genes with RNA levels that increased 4× or more between stage 11 and stage 13 was considered, and the RNA levels of these genes were plotted at different developmental stages. The rectangles delineate the 25^th and 75^th percentiles, the horizontal bar is the median, and the whiskers indicate the 10^th and 90^th percentiles.</p

PPARβ promotes differentiation but represses dorsal mesoderm and endoderm specification.

<p>(A)–(C) Embryos were injected with PPARβ MO or Co, allowed to develop until stage 18 (A) or stage 11.5 (B) and (D), and collected for extraction of total RNA. qRT-PCR runs for a selection of neural (blue), mesodermal (red), or endodermal (yellow) markers of differentiation (A) and (B) or of germ layer specification (C) were conducted. RNA levels were normalized to EEF1a and RPL8 and are presented as fold variation between MO and Co samples. Error bars represent the S.E.M. of 3 to 5 independent experiments. (D) Embryos were injected with PPARβ MO or Co, fixed at stg. 11.5, hemi-sectioned along the dorso–ventral axis, and processed for RNA <i>in situ</i> hybridization. While Mo injection did not affect the <i>sox17α</i> expression domain, it resulted in the expansion of <i>brachyury</i> expression dorsally (see the scale) but not ventrally. Arrows indicate the dorsal lip. (E) Quantification of the surface covered by the dorsal and ventral expression domains of <i>brachyury</i> in MO compared to Co hemi-sections. Error bar is the S.E.M. of 10 measurements. *: two-tailed Student’s t-test vs control, P<0.05.</p

PPARβ interprets a chromatin signature that is deposited at the end of the pluripotent stage.

<p>(A) Seven ‘K27’ genes and eight ‘K4 only’ genes were analysed by ChIP as indicated. Results are presented in a heat map (see also Supplementary Fig. 7). Variation in RNA expression upon PPARβ MO injection was obtained from the RNA-seq data or from qPCR validations. (B) ChIP with H3K27me3 antibody was conducted at stage 9 on 37 ‘PPARβ promoted genes’ and on 27 Control genes. PPARβ promoted genes were chosen among the top 200 most downregulated genes at stage 11, upon MO injection in the list presented in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083300#pone.0083300.s008" target="_blank">Table S1</a>, while Control genes did not show a change of expression upon MO injection. Results are presented as percentage of input. The threshold of 1% is indicated. Genes scored as positive for H3K27me3 are indicated by a red dot (see methods for further details on the definition of gene sets and on the criteria of scoring). (C) Sequential ChIPs were conducted. Note that no enrichment was observed for klf11 and for plcg1, which represent negative controls (see panel b). Error is the S.E.M of 2 independent experiments. (D) ChIP using PPARβ antibody was conducted at stage 11.5. Error is the S.E.M of 3 to 4 independent experiments. (E) ChIP with H3K27me3 antibody or PPARβ antibody and <i>q</i>RT-PCR were conducted on embryos treated with DZNep or DMSO and injected with PPARβ MO or Co. Error is the S.E.M of technical replicates of a single experiment that we have replicated with similar results.</p

PPARβ promotes the initiation of differentiation at gastrulation.

<p>(A) Rationale of the transcriptomic analysis of PPARβ loss-of-function. (B) The gene set consisting of predicted direct PPAR target genes in humans <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083300#pone.0083300-Heinaniemi1" target="_blank">[33]</a> was analysed by GSEA. (C) The Gene Ontology terms or the gene sets that were significantly (FDR<0.2) affected by PPARβ loss-of-function are presented. The gene sets corresponding to germ layer specification are also presented. (D) The gene sets consisting of the 100 most-induced genes and of the 100 most-decreased genes at gastrula (see also <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0083300#pone.0083300.s005" target="_blank">Fig. S5</a>) were analysed by GSEA. FDR, false discovery rate; GSEA, Gene Set Enrichment Analysis; NES, Normalized enrichment score.</p

A Dialogue between the Sirène Pathway in Synergids and the Fertilization Independent Seed Pathway in the Central Cell Controls Male Gamete Release during Double Fertilization in Arabidopsis

International audienceAngiosperms sexual reproduction involves interactions between the two female gametes in the embryo sac and the two male gametes released by the pollen tube. The two synergids of the embryo sac express the FERONIA/SIRÈNE receptor-like kinase, which controls the discharge of the two sperm cells from the pollen tube. FER/SRN may respond to a ligand from the pollen tube. Alternatively, the interaction between FER/SRN and a ligand from the embryo sac may lead to a state of competence of the synergids allowing pollen tube discharge. Here, we report the new mutant scylla (syl) impaired in the control of pollen tube discharge. This mutant also produces autonomous endosperm development in absence of fertilization—a trait associated with the FERTILIZATION INDEPENDENT SEED (FIS) mutant class. This led us to identify autonomous endosperm in srn mutants and to demonstrate synergistic interactions between srn and the fis mutants. In addition, the fis mutants display defects in pollen tube discharge as in srn and syl mutants, confirming the interaction between the two pathways. Our findings suggest that pollen tube discharge is controlled by an interaction between the synergids expressing SRN/FER and the central cell expressing FIS genes

Fatty acid synthesis and PPARalpha hand in hand.

How can an ex-orphan be adopted? Is it possible to do so by attributing to it a key endogenous ligand that regulates its central functions? In the recent issue of Cell, Chakravarthy et al. attempted to answer this question by characterizing a new physiologically relevant ligand for the ex-orphan receptor peroxisome proliferator activated receptor alpha (PPARalpha)