Cutin-Derived Oligomers Induce Hallmark Plant Immune Responses.

The cuticle constitutes the outermost defensive barrier of most land plants. It comprises a polymeric matrix - cutin, surrounded by soluble waxes. Moreover, the cuticle constitutes the first line of defense against pathogen invasion, while also protecting the plant from many abiotic stresses. Aliphatic monomers in cutin have been suggested to act as immune elicitors in plants. This study analyses the potential of cutin oligomers to activate rapid signaling outputs reminiscent of pattern-triggered immunity (PTI) in the model plant Arabidopsis. Cutin oligomeric mixtures led to Ca2+ influx and MAPK activation. Comparable responses were measured for cutin, which was also able to induce a reactive oxygen species (ROS) burst. Furthermore, cutin oligomer treatment resulted in a unique transcriptional reprogramming profile, having many archetypal features of PTI. Targeted spectroscopic and spectrometric analyses of the cutin oligomers suggest that the elicitors compounds consist mostly of two up to three 10,16-dihydroxyhexadecanoic acid monomers linked together through ester bonds. This study demonstrates that cutin breakdown products can act as inducers of early plant immune responses, which underlying mechanisms of perception and potential use in agriculture warrant further investigation.

Constraints on Early Dark Energy from Isotropic Cosmic Birefringence.

Polarization of the cosmic microwave background (CMB) is sensitive to new physics violating parity symmetry, such as the presence of a pseudoscalar "axionlike" field. Such a field may be responsible for early dark energy (EDE), which is active prior to recombination and provides a solution to the so-called Hubble tension. The EDE field coupled to photons in a parity-violating manner would rotate the plane of linear polarization of the CMB and produce a cross-correlation power spectrum of E- and B-mode polarization fields with opposite parities. In this Letter, we fit the EB power spectrum predicted by the photon-axion coupling of the EDE model with a potential V(ϕ)∝[1-cos(ϕ/f)]^{3} to polarization data from Planck. We find that the unique shape of the predicted EB power spectrum is not favored by the data and obtain a first constraint on the photon-axion coupling constant, g=(0.04±0.16)M_{Pl}^{-1} (68% C.L.), for the EDE model that best fits the CMB and galaxy clustering data. This constraint is independent of the miscalibration of polarization angles of the instrument or the polarized Galactic foreground emission. Our limit on g may have important implications for embedding EDE in fundamental physics, such as string theory.

Fine structure of the digestive tract epithelium in the terrestrial isopod. Armadillidium vulgare.

An ultrastructural study of the hindgut, associated hepatopancreatic lobes and hepatopancreatic ducts of the terrestrial isopod, Armadillidium vulgre was undertaken. The simple epithelium which lines the heptopancreas consists of two cell types, S and B. Both cell types have numerous microvilli. A simple epithelium consisting of one cell type lines the hepatopancreatic ducts and the hindgut. Microvilli are not evident in the duct. The cells of the duct and the hindgut are covered with a cuticle. Dense granular bodies are characteristic of the cytoplasm of the duct cells. The hindgut epithelial cells have pronounced apical and basal-lateral cytoplasmic infoldings. Apical infoldings from large subcuticular spaces, especially in the posterior hindgut. Microtubules and large numbers of mitochondria are associated with the cytoplasmic infoldings. Large microtubular bundles are seen in the peripheral cytoplasm, and residual bodies are present in the central cytoplasm. Lateral plasma membranes form septate desmosomes in the apical region of cells, while zonulae adherentes and intercellular spaces are found basal to the septate desmosomes. The cellular organization of the hindgut is suggestive of cells active in water and ion transport.