抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Background Lignin, nature’s dominant aromatic polymer, is found in most terrestrial plants in the approximate range of 15 to 40% dry weight and provides structural integrity. Traditionally, most large-scale industrial processes that use plant polysaccharides have burned lignin to generate the power needed to productively transform biomass. The advent of biorefineries that convert cellulosic biomass into liquid transportation fuels will generate substantially more lignin than necessary to power the operation, and therefore efforts are underway to transform it to value-added products. Production of biofuels from cellulosic biomass requires separation of large quantities of the aromatic polymer lignin. In planta genetic engineering, enhanced extraction methods, and a deeper understanding of the structure of lignin are yielding promising opportunities for efficient conversion of this renewable resource to carbon fibers, polymers, commodity chemicals, and fuels. [Credit: Oak Ridge National Laboratory, U.S. Department of Energy] Advances Bioengineering to modify lignin structure and/or incorporate atypical components has shown promise toward facilitating recovery and chemical transformation of lignin under biorefinery conditions. The flexibility in lignin monomer composition has proven useful for enhancing extraction efficiency. Both the mining of genetic variants in native populations of bioenergy crops and direct genetic manipulation of biosynthesis pathways have produced lignin feedstocks with unique properties for coproduct development. Advances in analytical chemistry and computational modeling detail the structure of the modified lignin and direct bioengineering strategies for targeted properties. Refinement of biomass pretreatment technologies has further facilitated lignin recovery and enables catalytic modifications for desired chemical and physical properties. Outlook Potential high-value products from isolated lignin include low-cost carbon fiber, engineering plastics and thermoplastic elastomers, polymeric foams and membranes, and a variety of fuels and chemicals all currently sourced from petroleum. These lignin coproducts must be low cost and perform as well as petroleum-derived counterparts. Each product stream has its own distinct challenges. Development of renewable lignin-based polymers requires improved processing technologies coupled to tailored bioenergy crops incorporating lignin with the desired chemical and physical properties. For fuels and chemicals, multiple strategies have emerged for lignin depolymerization and upgrading, including thermochemical treatments and homogeneous and heterogeneous catalysis. The multifunctional nature of lignin has historically yielded multiple product streams, which require extensive separation and purification procedures, but engineering plant feedstocks for greater structural homogeneity and tailored functionality reduces this challenge.

https://lifelong.unt.edu/sites/default/files/EmeritusCollege/Spring2015/Handouts/Lignin%20co-products.pdf

Lignin valorization: improving lignin processing in the biorefinery.

The colonization process of the infant gut microbiome has been called chaotic, but this view could reflect insufficient documentation of the factors affecting the microbiome. We performed a 2.5-y case study of the assembly of the human infant gut microbiome, to relate life events to microbiome composition and function. Sixty fecal samples were collected from a healthy infant along with a diary of diet and health status. Analysis of >300,000 16S rRNA genes indicated that the phylogenetic diversity of the microbiome increased gradually over time and that changes in community composition conformed to a smooth temporal gradient. In contrast, major taxonomic groups showed abrupt shifts in abundance corresponding to changes in diet or health. Community assembly was nonrandom: we observed discrete steps of bacterial succession punctuated by life events. Furthermore, analysis of ≈500,000 DNA metagenomic reads from 12 fecal samples revealed that the earliest microbiome was enriched in genes facilitating lactate utilization, and that functional genes involved in plant polysaccharide metabolism were present before the introduction of solid food, priming the infant gut for an adult diet. However, ingestion of table foods caused a sustained increase in the abundance of Bacteroidetes, elevated fecal short chain fatty acid levels, enrichment of genes associated with carbohydrate utilization, vitamin biosynthesis, and xenobiotic degradation, and a more stable community composition, all of which are characteristic of the adult microbiome. This study revealed that seemingly chaotic shifts in the microbiome are associated with life events; however, additional experiments ought to be conducted to assess how different infants respond to similar life events.

https://www.pnas.org/content/pnas/108/Supplement_1/4578.full.pdf

Succession of microbial consortia in the developing infant gut microbiome

and Fuels Changzhi Li,† Xiaochen Zhao,† Aiqin Wang,† George W. Huber,†,‡ and Tao Zhang*,† †State Key Laborotary of Catalysis, iChEM (Collaborative Innovation Center of Chemistry for Energy Materials), Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China ‡Department of Chemical and Biological Engineering, University of WisconsinMadison, Madison, Wisconsin 53706, United States

Catalytic Transformation of Lignin for the Production of Chemicals and Fuels

Lignin is the generic term for a large group of aromatic polymers resulting from the oxidative combinatorial coupling of 4-hydroxyphenylpropanoids ([Boerjan et al., 2003][1]; [Ralph et al., 2004][2]). These polymers are deposited predominantly in the walls of secondarily thickened cells, making them

Lignin Biosynthesis and Structure

The invention provides methods for increasing the level of fermentable carbohydrates in a biofuel crop plant such as alfalfa or switchgrass, by modification of the lignin biosynthetic pathway. Also provided are plants prepared by the methods of the invention. Methods for processing plant tissue and for producing ethanol by utilizing such plants are also provided.

Biofuel production methods and compositions

Controlled silencing of 4-coumarate:CoA ligase alters lignocellulose composition without affecting stem growth.

Chemical syntheses of caffeoyl and 5-OH coniferyl aldehydes and alcohols and determination of lignin O-methyltransferase activities in dicot and monocot species

As a class of important catalysts and adsorbents, zeolites are normally prepared through hydrothermal synthesis, whereby a relatively long crystallization time and use of a large amount water solvent strongly hinder the enhancement of zeolite space-time yields (STYs), which is a critical factor for the industrial manufacturing. To overcome this limitation, herein we report a novel strategy for highly efficient zeolite synthesis by means of fast crystallization at high temperatures (200–240 °C) in the absence of water solvent. This concept significantly enhances the crystallization rates and allows drastic reduction of the time required for crystallization of the zeolite frameworks such as the crystallization of MFI from 12–24 h at 180 °C to 0.5 h at 240 °C and RUB-36 from 14 days at 140 °C to 1.5 days at 200 °C. Together with much better utilization of the reactor volume, the space-time yields (STYs) for zeolites prepared from high-temperature synthesis in the absence of water solvent can be remarkably increased. The STYs of MFI and RUB-36 are as high as 11 000 and 178 kg m−3 per day, which are almost two orders of magnitude higher than those of conventional hydrothermal synthesis. This novel synthesis method should be applicable for synthesizing a wide variety of zeolite structures and bears the potential for highly efficient zeolite synthesis on an industrial scale.

Generalized high-temperature synthesis of zeolite catalysts with unpredictably high space-time yields (STYs)

The most used method for preparation of zeolites is hydrothermal synthesis from silicate or aluminosilicate gels at temperatures in the range of 60–200 °C. Excess water used in the industrial process results in several issues, including high autogeneous pressure, low efficiency, pollution, etc. To solve these problems, several strategies have been developed. This review describes the solvent-free synthesis of zeolites. The combination of solvent-free synthesis and organotemplate-free synthesis can open the pathway to a highly sustainable zeolite synthesis protocol in industry.

Fang Chen

Papers

Biofuel production methods and compositions

Controlled silencing of 4-coumarate:CoA ligase alters lignocellulose composition without affecting stem growth.

Chemical syntheses of caffeoyl and 5-OH coniferyl aldehydes and alcohols and determination of lignin O-methyltransferase activities in dicot and monocot species

Generalized high-temperature synthesis of zeolite catalysts with unpredictably high space-time yields (STYs)

Solvent-free synthesis of zeolite catalysts