22 research outputs found
An Efficient and Faithful in Vitro Replication System for Threose Nucleic Acid
The
emerging field of synthetic genetics provides an opportunity
to explore the structural and functional properties of synthetic genetic
polymers by in vitro selection. Limiting this process, however, is
the availability of enzymes that allow for the synthesis and propagation
of genetic information present in unnatural nucleic acid sequences.
Here, we report the development of a transcription and reverse-transcription
system that can replicate unnatural genetic polymers composed of threose
nucleic acids (TNA). TNA is a potential progenitor of RNA in which
the natural ribose sugar found in RNA has been replaced with an unnatural
threose sugar. Using commercial polymerases that recognize TNA, we
demonstrate that an unbiased three-letter and two different biased
four-letter genetic alphabets replicate in vitro with high efficiency
and high overall fidelity. We validated the replication system by
performing one cycle of transcription, selection, reverse transcription,
and amplification on a library of 10<sup>14</sup> DNA templates and
observed ∼380-fold enrichment after one round of selection
for a biotinylated template. We further show that TNA polymers are
stable to enzymes that degrade DNA and RNA. These results provide
the methodology needed to evolve biologically stable aptamers and
enzymes for exobiology and molecular medicine
Rac1 regulates M1 protein-induced lung damage.
<p>Representative haematoxylin & eosin sections of lung. Sham animals were treated with PBS only. Separate mice were pretreated with vehicle (PBS) and 0.5 or 5 mg/kg of the Rac1 inhibitor NSC23766 10 min prior to M1 protein administration. Samples were harvested 4 h after M1 protein challenge. Scale bar indicates 100 µm. Histology score of lung injury. Data represents mean ± SEM, *<i>P</i> < 0.05 <i>vs.</i> Sham and <b><sup>#</sup></b><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
Macrophages (RAW264.7) and endothelial cells (eEND2) were co-incubated with 10 µM Rac-1 inhibitor NSC23766 1 h prior to M1 protein (0.5 µg/ml) stimulation.
<p>ELISA was used to quantify the levels of CXCL2 in the supernatants 4 h after M1 protein challenge. Data represents mean ± SEM, *<i>P</i> < 0.05 <i>vs.</i> Sham and <sup>#</sup><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
M1 protein-induced Mac-1 expression on neutrophils <i>in vivo</i>.
<p>Mac-1 expression on neutrophils in vehicle (PBS) or NSC23766 (0.5 or 5 mg/kg), treated animals 4 h after M1 protein injection. Fluorescence intensity is shown on the x-axis and cell counts on the y-axis. Data represents mean ± SEM, <sup>*</sup><i>P</i> < 0.05 <i>vs.</i> Sham and <sup>#</sup><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
M1 protein-induced Rac1 activity in the lung. Mice were treated with the Rac1 inhibitor NSC23766 (5 mg/kg) or vehicle (PBS) 10 min prior to M1 protein injection.
<p>Mice treated with PBS served as sham animals. Samples were harvested 4 h after M1 protein challenge. <i>n</i> = 3.</p
Systemic leukocyte differential counts.
<p>Blood was collected from sham animals receiving PBS intravenously only as well as mice were pretreated i.p. with vehicle (PBS) or NSC23766 10 min prior to M1 protein challenge for 4 h. Cells were identified as monomorphonuclear leukocytes (MNL) and polymorphonuclear leukocytes (PMNL). Data represents mean ± SEM, 10<sup>6</sup> cells/ml and <i>n = </i>5.</p>*<p><i>P</i> < 0.05 <i>vs.</i> Sham and <sup>#</sup><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
Rac1 regulates M1 protein-induced neutrophil infiltration in the lung.
<p>MPO levels and number of BALF neutrophils in the lung. Animals were treated with the Rac1 inhibitor NSC23766 (0.5 or 5 mg/kg) or vehicle (PBS) 10 min prior to M1 protein injection. Samples were harvested 4 h after M1 protein challenge. Mice treated with PBS served as sham animals. Data represents mean ± SEM, *<i>P</i> < 0.05 <i>vs.</i> Sham and <b><sup>#</sup></b><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
Rac1 regulates M1 protein-induced edema formation in the lung.
<p>Mice were treated with the Rac1 inhibitor NSC23766 (0.5 or 5 mg/kg) or vehicle (PBS) 10 min prior to M1 protein injection. Mice treated with PBS served as sham animals. Samples were harvested 4 h after M1 protein challenge. Data represents mean ± SEM, *<i>P</i> < 0.05 <i>vs.</i> Sham and <b><sup>#</sup></b><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
Rac1 regulates M1 protein-induced gene expression of CXC chemokines in alveolar macrophages.
<p>CXCL1 and CXCL2 in alveolar macrophages 30 min after M1 protein injection. Levels of CXCL1 and CXCL2 mRNA were normalized to mRNA levels of β-actin. Data represents mean ± SEM, *<i>P</i> < 0.05 <i>vs.</i> Sham and <b><sup>#</sup></b><i>P</i> < 0.05 <i>vs.</i> Vehicle+M1 protein, <i>n = </i>5.</p
Simultaneous Purification and Perforation of Low-Grade Si Sources for Lithium-Ion Battery Anode
Silicon is regarded as one of the
most promising candidates for lithium-ion battery anodes because of
its abundance and high theoretical capacity. Various silicon nanostructures
have been heavily investigated to improve electrochemical performance
by addressing issues related to structure fracture and unstable solid–electrolyte
interphase (SEI). However, to further enable widespread applications,
scalable and cost-effective processes need to be developed to produce
these nanostructures at large quantity with finely controlled structures
and morphologies. In this study, we develop a scalable and low cost
process to produce porous silicon directly from low grade silicon
through ball-milling and modified metal-assisted chemical etching.
The morphology of porous silicon can be drastically changed from porous-network
to nanowire-array by adjusting the component in reaction solutions.
Meanwhile, this perforation process can also effectively remove the
impurities and, therefore, increase Si purity (up to 99.4%) significantly
from low-grade and low-cost ferrosilicon (purity of 83.4%) sources.
The electrochemical examinations indicate that these porous silicon
structures with carbon treatment can deliver a stable capacity of
1287 mAh g<sup>–1</sup> over 100 cycles at a current density
of 2 A g<sup>–1</sup>. This type of purified porous silicon
with finely controlled morphology, produced by a scalable and cost-effective
fabrication process, can also serve as promising candidates for many
other energy applications, such as thermoelectrics and solar energy
conversion devices