Parallel laboratory evolution and rational debugging reveal genomic plasticity to S. cerevisiae synthetic chromosome XIV defects

Synthetic chromosome engineering is a complex process due to the need to identify and repair growth defects and deal with combinatorial gene essentiality when rearranging chromosomes. To alleviate these issues, we have demonstrated novel approaches for repairing and rearranging synthetic Saccharomyces cerevisiae genomes. We have designed, constructed, and restored wild-type fitness to a synthetic 753,096-bp version of S. cerevisiae chromosome XIV as part of the Synthetic Yeast Genome project. In parallel to the use of rational engineering approaches to restore wild-type fitness, we used adaptive laboratory evolution to generate a general growth-defect-suppressor rearrangement in the form of increased TAR1 copy number. We also extended the utility of the synthetic chromosome recombination and modification by loxPsym-mediated evolution (SCRaMbLE) system by engineering synthetic-wild-type tetraploid hybrid strains that buffer against essential gene loss, highlighting the plasticity of the S. cerevisiae genome in the presence of rational and non-rational modifications. </p

THE PULFRICH PENDULUM EFFECT WITH FILTERING PORTIONS OF BOTH EYES.

Abstract not availabl

Adaptive Algorithms for Estimating Betweenness and k -path Centralities

International audienc

Reduction of measurement noise in a continuous glucose monitor by coating the sensor with a zwitterionic polymer

© 2018, Nature Publishing Group. All rights reserved. Continuous glucose monitors (CGMs), used by patients with diabetes mellitus, can autonomously track fluctuations in blood glucose over time. However, the signal produced by CGMs during the initial recording period following sensor implantation contains substantial noise, requiring frequent recalibration via finger-prick tests. Here, we show that coating the sensor with a zwitterionic polymer, found via a combinatorial chemistry approach, significantly reduces signal noise and improves CGM performance. We evaluated the polymer-coated sensors in mice as well as in healthy and diabetic non-human primates, and show that the sensors accurately record glucose levels without the need for recalibration. We also show that the coated sensors significantly abrogated immune responses, as indicated by histology, fluorescent whole-body imaging of inflammation-associated protease activity and gene expression of inflammation markers. The polymer coating may allow CGMs to become standalone measuring devices.This work was supported by the Leona M. and Harry B. Helmsley Charitable Trust Foundation (2015PG-T1D063), Juvenile Diabetes Research Foundation (JDRF) (Grant 17-2007-1063), and National Institutes of Health (Grants EB000244, EB000351, DE013023 and CA151884), and through a generous gift from the Tayebati Family Foundation. J.C.D was supported by JDRF postdoctoral fellowship (Grant 3-PDF-2015-91-A-N). J.O. is supported by the National Institutes of Health (NIH/NIDDK) R01DK091526 and the Chicago Diabetes Project. X.X. was supported by the 100 Talents Program of Sun Yat-Sen University (76120-18821104) and 1000 Talents Youth Program of China and would like to acknowledge financial support from the National Natural Science Foundation of China (Grant No.51705543, 61771498 and 31530023) and Science and Technology Program of Guangzhou, China (Grant No. 20180310097). And, of extreme importance, the authors thank the Histology and Whole Animal Imaging cores for use of resources (Swanson Biotechnology Center, David H. Koch Institute for Integrative Cancer Research at MIT)

An alpine treeline in a carbon dioxide-rich world : synthesis of a nine-year free-air carbon dioxide enrichment study

ISSN:0029-8549ISSN:1432-193

Preparation and Properties of Asymmetric Vesicles That Mimic Cell Membranes: EFFECT UPON LIPID RAFT FORMATION AND TRANSMEMBRANE HELIX ORIENTATION*S⃞

A methyl-β-cyclodextrin-induced lipid exchange technique was devised to prepare small unilamellar vesicles with stable asymmetric lipid compositions. Asymmetric vesicles that mimic biological membranes were prepared with sphingomyelin (SM) or SM mixed with 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) as the predominant lipids in the outer leaflet and dioleoylphosphatidylcholine (DOPC), POPC, 1-palmitoyl-2-oleoyl-phosphatidyl-l-serine (POPS), or POPS mixed with 1-palmitoyl-2-oleoyl-phosphatidylethanolamine (POPE) in the inner leaflet. Fluorescence-based assays were developed to confirm lipid asymmetry. Cholesterol was introduced into these vesicles using a second methyl-β-cyclodextrin exchange step. In asymmetric vesicles composed of SM outside, DOPC inside (SMo/DOPCi) or SM outside, 2:1 mol:mol POPE:POPS inside (SMo/2:1 POPE:POPSi) the outer leaflet SM formed an ordered state with a thermal stability similar to that in pure SM vesicles and significantly greater than that in symmetric vesicles with the same overall lipid composition. Analogous behavior was observed in vesicles containing cholesterol. This shows that an asymmetric lipid distribution like that in eukaryotic plasma membranes can be conducive to ordered domain (raft) formation. Furthermore asymmetric vesicles containing ∼25 mol % cholesterol formed ordered domains more thermally stable than those in asymmetric vesicles lacking cholesterol, showing that the crucial ability of cholesterol to stabilize ordered domain formation is likely to contribute to ordered domain formation in cell membranes. Additional studies demonstrated that hydrophobic helix orientation is affected by lipid asymmetry with asymmetry favoring formation of the transmembrane configuration. The ability to form asymmetric vesicles represents an important improvement in model membrane studies and should find many applications in the future