Description: The susceptibility of native and non-native populations of the red alga Gracilaria vermiculophylla to fouling was compared in common garden experiments. Native and non-native algae were enclosed into dialysis membrane tubes, and the tubes were exposed to natural fouling. Fouling on the outside of the tubes was mediated by chemical compounds excreted by G. vermiculophylla that diffused through the membranes. Fouling pressure was significantly higher in the Kiel Fjord (non-native range) than in Akkeshi Bay (native range), but, at both sites, tubes containing non-native G. vermiculophylla were less fouled than those with native conspecifics. This is the first in situ evidence that susceptibility to fouling differs between native and non-native populations of an aquatic organism. The technique of enclosing organisms into dialysis tubes represents a simple, efficient and accurate way to test chemical antifouling defenses and could possibly be applied to other organisms.

Description: Fouling is a stressor that might determine the fate of seaweeds, but reports of algal adaptation to epibiosis are scarce. Previous comparisons have shown resistance to epibionts can be higher in non-native than in resident seaweed species, but we do not know whether it is an intrinsic trait of the non-natives or it has been acquired during the invasion process. We here compared native and non-native populations of the same algal species to elucidate this question. Resistance against two groups of epiphytes was assessed in living thalli and in artificial substrata coated with surface extracts, both gained from four Asian (native) and four European (non-native) populations of the red alga Gracilaria vermiculophylla. Two diatom species and two filamentous macroalgae were used as micro- and macro-epiphytes, and one of each type was collected in Asia, while the other came from Europe. Laboratory assays were done in both distributional ranges of G. vermiculophylla and in different seasons. We used a fully crossed design with the factors (i) ‘Origin of Gracilaria’, (ii) ‘Origin of epiphytes’, (iii) ‘Season’ and (iv) ‘Solvent used for extraction’. Both groups of epiphytes, regardless of their origin, attached less to living thalli and to surface extracts from non-native G. vermiculophylla. Fewer diatoms attached to hexane-based extracts, while fewer Ceramium filaments settled on extracts gained with dichloromethane. Our results show for the first time that non-native individuals of a seaweed are better defended against epiphytes than native conspecifics. Furthermore, we found evidence that at least a part of the defence is based on extractable secondary metabolites. We suggest that an enhanced defence against epiphytes after introduction is one reason for G. vermiculophylla’s invasion success. Our observation may also apply to other basibiont–epibiont interactions and could be a key feature of seaweed bioinvasions.

Description: Author(s): Madhab Neupane, Su-Yang Xu, Nasser Alidoust, Guang Bian, D. J. Kim, Chang Liu, I. Belopolski, T.-R. Chang, H.-T. Jeng, T. Durakiewicz, H. Lin, A. Bansil, Z. Fisk, and M. Z. Hasan We present angle-resolved photoemission studies on the rare-earth-hexaboride YbB 6 , which has recently been predicted to be a topological Kondo insulator. Our data do not agree with the prediction and instead show that YbB 6 exhibits a novel topological insulator state in the absence of a Kondo mechan... [Phys. Rev. Lett. 114, 016403] Published Wed Jan 07, 2015

Description: Retinal ganglion cells (RGCs) are projection neurons in the neural retina that relay visual information from the environment to the central nervous system. The early expression of MATH5 endows the post-mitotic precursors with RGC competence and leads to the activation of Brn3b that marks committed RGCs. Nevertheless, this fate commitment process and, specifically, regulation of Brn3b remain elusive. To explore the molecular mechanisms underlying RGC generation in the mouse retina, we analyzed the expression and function of Fez family zinc finger 2 (FEZF2), a transcription factor critical for the development of projection neurons in the cerebral cortex. Fezf2 mRNA and protein were transiently expressed at embryonic day 16.5 in the inner neuroblast layer and the prospective ganglion cell layer of the retina, respectively. Knockout of Fezf2 in the developing retina reduced BRN3B+ cells and increased apoptotic cell markers. Fezf2 knockdown by retinal in utero electroporation diminished BRN3B but not the coexpressed ISLET1 and BRN3A, indicating that the BRN3B decrease was the cause, not the result, of the overall reduction of BRN3B+ RGCs in the Fezf2 knockout retina. Moreover, the mRNA and promoter activity of Brn3b were increased in vitro by FEZF2, which bound to a 5′ regulatory fragment in the Brn3b genomic locus. These results indicate that transient expression of Fezf2 in the retina modulates the transcription of Brn3b and the survival of RGCs. This study improves our understanding of the transcriptional cascade required for the specification of RGCs and provides novel insights into the molecular basis of retinal development.