Prof. Ulli Tepass named a Fellow of the Royal Society of Canada

Congratulations to Professor and Chair Ulli Tepass who was just elected a Fellow of the Royal Society of Canada – one of the highest scientific honours given in Canada!  The Royal Society of Canada’s citations for Ulli states:

Ulrich Tepass, Department of Cell & Systems Biology
Tepass is an international leader in the analysis of epithelial cell polarity and cell adhesion using the genetic model organism, the fruit fly. He was among the first to characterize an epithelial polarity factor in 1990, and since then has made numerous seminal contributions to our understanding of the molecular regulation of cell polarity and adhesion and the developmental significance of these processes. The fundamental insights that this work has generated are relevant for our understanding of human disease, including blindness and most forms of cancer.

Clonal Relationships Impact Neuronal Tuning within a Phylogenetically Ancient Vertebrate Brain Structure

Muldal AM, Lillicrap TP, Richards BA, Akerman CJ

Curr. Biol. 2014 Aug;24(16):1929-33

PMID: 25127219

Abstract

Understanding how neurons acquire specific response properties is a major goal in neuroscience. Recent studies in mouse neocortex have shown that “sister neurons” derived from the same cortical progenitor cell have a greater probability of forming synaptic connections with one another [1, 2] and are biased to respond to similar sensory stimuli [3, 4]. However, it is unknown whether such lineage-based rules contribute to functional circuit organization across different species and brain regions [5]. To address this question, we examined the influence of lineage on the response properties of neurons within the optic tectum, a visual brain area found in all vertebrates [6]. Tectal neurons possess well-defined spatial receptive fields (RFs) whose center positions are retinotopically organized [7]. If lineage relationships do not influence the functional properties of tectal neurons, one prediction is that the RF positions of sister neurons should be no more (or less) similar to one another than those of neighboring control neurons. To test this prediction, we developed a protocol to unambiguously identify the daughter neurons derived from single tectal progenitor cells in Xenopus laevis tadpoles. We combined this approach with in vivo two-photon calcium imaging in order to characterize the RF properties of tectal neurons. Our data reveal that the RF centers of sister neurons are significantly more similar than would be expected by chance. Ontogenetic relationships therefore influence the fine-scale topography of the retinotectal map, indicating that lineage relationships may represent a general and evolutionarily conserved principle that contributes to the organization of neural circuits.

Detection of Parasitic Plant Suicide Germination Compounds Using a High-Throughput Arabidopsis HTL/KAI2 Strigolactone Perception System

Toh S, Holbrook-Smith D, Stokes ME, Tsuchiya Y, McCourt P

Chem. Biol. 2014 Aug;21(8):988-98

PMID: 25126711

Abstract

Strigolactones are terpenoid-based plant hormones that act as communication signals within a plant, between plants and fungi, and between parasitic plants and their hosts. Here we show that an active enantiomer form of the strigolactone GR24, the germination stimulant karrikin, and a number of structurally related small molecules called cotylimides all bind the HTL/KAI2 α/β hydrolase in Arabidopsis. Strigolactones and cotylimides also promoted an interaction between HTL/KAI2 and the F-box protein MAX2 in yeast. Identification of this chemically dependent protein-protein interaction prompted the development of a yeast-based, high-throughput chemical screen for potential strigolactone mimics. Of the 40 lead compounds identified, three were found to have in planta strigolactone activity using Arabidopsis-based assays. More importantly, these three compounds were all found to stimulate suicide germination of the obligate parasitic plant Striga hermonthica. These results suggest that screening strategies involving yeast/Arabidopsis models may be useful in combating parasitic plant infestations.