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38. Interspecific Sharing of Closely Related Chloroplast Genome Haplotypes among Sclerophyllous Oaks in the Hot-Dry Valley of the Jinsha River, Southwestern China.

Author

Li, Yao, Tan, Chao, Zhang, Wenxu, Wang, Lu, Yang, Zhi, Fang, Yanming, Yang, Yong, and Mao, Lingfeng

Subjects
CHLOROPLAST DNA, HAPLOTYPES, GENETIC variation, NUCLEAR DNA, PHYLOGENY, RIBOSOMAL DNA
Abstract

Evergreen sclerophyllous oak forests (ESOFs) in southwestern China are a special vegetation type developed in response to the expansion of arid habitats after the uplift of the Himalayas. Here, we used chloroplast (cp) DNA and nuclear ribosomal (nr) DNA to investigate the fine-scale genetic variation patterns of six sympatric oaks (Quercus, Fagaceae) in the hot-dry valley ESOFs of the Jinsha River, southwestern China. Three cp genomes were assembled for each species. Nine cp genome haplotypes and 16 nrDNA haplotypes were identified based on single-nucleotide variants and indels. Our results demonstrated that discordance existed between the cpDNA and nrDNA phylogenies of the sclerophyllous oaks in section Ilex. The nrDNA phylogeny was consistent with species boundaries, while the cpDNA phylogeny was decoupled from taxonomy. Interspecific sharing of closely related cp genome haplotypes was detected between Quercus cocciferoides and the other two sclerophyllous oaks, Q. longispica and Q. franchetii. Specifically, Q. cocciferoides and Q. longispica sampled in a mixed stand exhibited two haplotypes that differed by a 9 bp indel. The local distribution of the two highly similar haplotypes suggested that they may have arisen from ancient introgression. Given that the two species have diverged for a long time, it is possible that the ancestral cp genome of one species was captured by another species through asymmetric introgression in early times, and an indel event occurred subsequently. Phylogenetic analyses using more previously published cp genome sequences indicated that Q. cocciferoides and Q. franchetii shared multiple cpDNA lineages of Ilex oaks, which may be caused by shared ancestral polymorphism and/or ancient introgression. Our study showed that at least three highly variable regions (ψycf1, ndhF-rpl32, and trnKUUU-rps16 or rpl32-trnLUAG) can distinguish the nine haplotypes identified by whole-cp genome sequences. These markers are useful for the evolutionary studies of the maternal lineages of oaks in hot-dry valley ESOFs. [ABSTRACT FROM AUTHOR]

Published
2024
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41. Cleavable comonomers enable degradable, recyclable thermoset plastics

Author

Shieh, Peyton, Zhang, Wenxu, Husted, Keith E. L., Kristufek, Samantha L., Xiong, Boya, Lundberg, David J., and Lem, Jet

Subjects
Thermosetting plastics -- Chemical properties, Plastics -- Biodegradation, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Thermosets--polymeric materials that adopt a permanent shape upon curing--have a key role in the modern plastics and rubber industries, comprising about 20 per cent of polymeric materials manufactured today, with a worldwide annual production of about 65 million tons.sup.1,2. The high density of crosslinks that gives thermosets their useful properties (for example, chemical and thermal resistance and tensile strength) comes at the expense of degradability and recyclability. Here, using the industrial thermoset polydicyclopentadiene as a model system, we show that when a small number of cleavable bonds are selectively installed within the strands of thermosets using a comonomer additive in otherwise traditional curing workflows, the resulting materials can display the same mechanical properties as the native material, but they can undergo triggered, mild degradation to yield soluble, recyclable products of controlled size and functionality. By contrast, installation of cleavable crosslinks, even at much higher loadings, does not produce degradable materials. These findings reveal that optimization of the cleavable bond location can be used as a design principle to achieve controlled thermoset degradation. Moreover, we introduce a class of recyclable thermosets poised for rapid deployment. A method of endowing thermoset plastics with a degree of recyclability and reprocessability by incorporating cleavable chemical linkages in the strands of the polymer, rather than in the crosslinks, is presented., Author(s): Peyton Shieh [sup.1] , Wenxu Zhang [sup.1] , Keith E. L. Husted [sup.1] , Samantha L. Kristufek [sup.1] , Boya Xiong [sup.2] , David J. Lundberg [sup.1] [sup.3] , [...]

Published
2020
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47. Synthesis, Properties of MIL‐101(Al)‐NH2 Polymers Capable of Absorbing Vapor, Liquid Water Simultaneously.

Author

Yang, Cailing, Zhang, Wenxu, Xu, Rongnian, Peng, Huaiwu, Zhang, Zhenshi, Liu, Xiaomei, Li, Li, Li, Tingli, Li, Jing, Liu, Pengbo, Jin, Xinlu, Ma, Yuanyuan, and Lei, Ziqiang

Subjects
ACRYLIC acid, POLYACRYLIC acid, WATER vapor, TRANSMISSION electron microscopes, SCANNING electron microscopes, INFRARED spectroscopy, COMPOSITE materials, ADSORPTION capacity
Abstract

Modified MIL‐101(Al)‐NH2 (MIL‐101(Al)‐NH2‐net) is used as a crosslinking agent and acrylic acid (AA) as a monomer, the MIL‐101(Al)‐NH2‐net grafted polyacrylic acid (MIL‐101(Al)‐NH2‐net‐g‐PAA (MAP)) composite water‐absorbent material is synthesized using the free radical polymerization method to study the application of composite absorbent materials in water collection. The structure and morphology of the composite water‐absorbent material are characterized using Fourier transform infrared spectrometry (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer Emmett Teller (BET), and thermogravimetric analysis (TG), and the contents of ammonium persulfate (APS), MIL‐101(Al)‐NH2‐net, and neutralization degree of AA are optimized. Under optimal conditions, the water absorption ratios of the composite materials in distilled water, tap water, and 0.9% NaCl solution are 744, 169.5, and 85.5 g g−1. In addition, the properties of collecting water vapor are investigated. At 25 °C, 50% Relative Humidity (RH), 70% RH, and 90% RH, the MAP water vapor adsorption capacity is 0.0312, 0.5760, and 1.6856 g g−1, respectively. The water vapor adsorption of MIL‐101(Al)‐NH2 and MIL‐101(Al)‐NH2 self‐polymerization products are 0.025 and 0.1278 g g−1, respectively. The result showed that autopolymerization can improve the water vapor adsorption performance. [ABSTRACT FROM AUTHOR]

Published
2024
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49. Towards Single-Molecule Nanopore DNA and Protein Sequencing

Author

Zhang, Wenxu

Subjects
Materials Science
Abstract

Precise determination of DNA and protein sequences is essential to understanding biological systems. After more than 30 years of development, nanopore technology has been demonstrated to be capable of real-time long-read sequencing of single DNA molecules. However, current nanopore DNA sequencing is still limited by low consensus accuracy due to systematic error in reading homopolymers and other sequences with similar levels of ionic blockage. While nanopore DNA sequencing technology is revolutionizing genomics research, whether an analogous nanopore technology can be used to identify and sequence protein molecules remains largely unexplored. In the first part of this dissertation, I investigated the feasibility of ultraacurate nanopore DNA sequencing based on experimental sequencing data and computational modeling. In the second part of the dissertation, I investigated the theoretical feasibility of protein identification and sequencing using nanopore technologies. I also presented experimental work on the development of an integrated opto-electrical system for nanopore fabrication process and its potential application in single-molecule protein identification using high-speed optical detection.

Published
2021

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