Development of protein microarrays and label-free microfluidic immunoassays

Ph.DDOCTOR OF PHILOSOPH

Conservation and divergence of microRNAs and their functions in Euphorbiaceous plants

MicroRNAs (miRNAs) are ∼21 nt non-coding RNAs which regulate post-transcriptional gene expression. miRNAs are key regulators of nearly all essential biological processes. Aiming at understanding miRNA’s functions in Euphorbiaceae, a large flowering plant family, we performed a genome-scale systematic study of miRNAs in Euphorbiaceae, by combining computational prediction and experimental analysis to overcome the difficulty of lack of genomes for most Euphorbiaceous species. Specifically, we predicted 85 conserved miRNAs in 23 families in the Castor bean (Ricinus communis), and experimentally verified and characterized 58 (68.2%) of the 85 miRNAs in at least one of four Euphorbiaceous species, the Castor bean, the Cassava (Manihot esculenta), the Rubber tree (Hevea brasiliensis) and the Jatropha (Jatropha curcas) during normal seedling development. To elucidate their function in stress response, we verified and profiled 48 (56.5%) of the 85 miRNAs under cold and drought stresses as well as during the processes of stress recovery. The results revealed some species- and condition-specific miRNA expression patterns. Finally, we predicted 258 miRNA:target partners, and identified the cleavage sites of six out of ten miRNA targets by a modified 5′ RACE. This study produced the first collection of miRNAs and their targets in Euphorbiaceae. Our results revealed wide conservation of many miRNAs and diverse functions in Euphorbiaceous plants during seedling growth and in response to abiotic stresses

Cassava genome from a wild ancestor to cultivated varieties

Cassava is a major tropical food crop in the Euphorbiaceae family that has high carbohydrate production potential and adaptability to diverse environments. Here we present the draft genome sequences of a wild ancestor and a domesticated variety of cassava and comparative analyses with a partial inbred line. We identify 1,584 and 1,678 gene models specific to the wild and domesticated varieties, respectively, and discover high heterozygosity and millions of single-nucleotide variations. Our analyses reveal that genes involved in photosynthesis, starch accumulation and abiotic stresses have been positively selected, whereas those involved in cell wall biosynthesis and secondary metabolism, including cyanogenic glucoside formation, have been negatively selected in the cultivated varieties, reflecting the result of natural selection and domestication. Differences in microRNA genes and retrotransposon regulation could partly explain an increased carbon flux towards starch accumulation and reduced cyanogenic glucoside accumulation in domesticated cassava. These results may contribute to genetic improvement of cassava through better understanding of its biology

Conformational Changes of Acyl Carrier Protein Switch the Chain Length Preference of Acyl-ACP Thioesterase ChFatB2

Microbial fatty acids are synthesized by Type II fatty acid synthase and could be tailored by acyl-ACP thioesterase. With the prospects of medium-chain fatty-acid-derivative biofuels, the selectivity of thioesterase has been studied to control the fatty acid product chain length. Here, we report an alternative approach by manipulating the acyl carrier protein portion of acyl-ACP to switch the chain length propensity of the thioesterase. It was demonstrated that ChFatB2 from Cuphea hookeriana preferred C10-ACP to C8-ACP with ACP from E. coli, while converting preference to C8-ACP with ACP from Cuphea lanceolate. Circular dichroism (CD) results indicated that the C8-EcACP encountered a 34.4% α-helix increment compared to C10-EcACP, which resulted in an approximate binding affinity decrease in ChFatB2 compared to C10-EcACP. Similarly, the C10-ClACP2 suffered a 45% decrease in helix content compared to C8–ClACP2, and the conformational changes resulted in an 18% binding affinity decline with ChFatB2 compared with C10-ClACP2. In brief, the study demonstrates that the ACP portion of acyl-ACP contributes to the selectivity of acyl-ACP thioesterase, and the conformational changes of EcACP and ClACP2 switch the chain length preference of ChFatB2 between C8 and C10. The result provides fundamentals for the directed synthesis of medium-chain fatty acids based on regulating the conformational changes of ACPs

BIO-ASSAY USING LIQUID CRYSTALS

US20110200986A1Published Applicatio

Progress in thermal energy storage technologies for achieving carbon neutrality

Abstract China is committed to the targets of achieving peak CO2 emissions around 2030 and realizing carbon neutrality around 2060. To realize carbon neutrality, people are seeking to replace fossil fuel with renewable energy. Thermal energy storage is the key to overcoming the intermittence and fluctuation of renewable energy utilization. In this paper, the relation between renewable energy and thermal energy storage is first addressed. Then, the classifications of thermal energy storage and Carnot batteries are given. The aim of this review is to provide an insight into the promising thermal energy storage technologies for the application of renewable energy in order to realize carbon neutrality. Three types of heat storage methods, especially latent heat storage and thermochemical heat storage, are analyzed in detail. The application of thermal energy storage is influenced by many heat storage properties, such as temperature range, heat storage capacity, cost, stability, and technical readiness. Therefore, the heat storage properties for different heat storage technologies are reviewed and compared. The advantage and challenge of different heat storage technologies and Carnot batteries for carbon neutrality processes are analyzed. Finally, the prospects of different heat storage technologies are summarized

Molecular mapping of the hybrid necrosis gene NetJingY176 in Aegilops tauschii using microsatellite markers

The rich genetic variation preserved in collections of Aegilops tauschii can be readily exploited to improve common wheat using synthetic hexaploid wheat lines. However, hybrid necrosis, which is characterized by progressive death of leaves or plants, has been observed in certain interspecific crosses between tetraploid wheat and Ae. tauschii. The aim of this study was to construct a fine genetic map of a gene (temporarily named NetJingY176) conferring hybrid necrosis in Ae. tauschii accession Jing Y176. A triploid F1 population derived from distant hybridization between Ae. tauschii and tetraploid wheat was used to map the gene with microsatellite markers. The newly developed markers XsdauK539 and XsdauK561 co-segregated with NetJingY176 on chromosome arm 2DS. The tightly linked markers developed in this study were used to genotype 91 Ae. tauschii accessions. The marker genotype analysis suggested that 49.45% of the Ae. tauschii accessions carry NetJingY176. Interestingly, hybrid necrosis genotypes tended to appear more commonly in Ae. tauschii ssp. tauschii than in Ae. tauschii ssp. strangulata

Protein Adsorption Mechanisms Determine the Efficiency of Thermally Controlled Cell Adhesion on Poly(<i>N</i>‑isopropyl acrylamide) Brushes

This study investigated the impact of the protein adsorption mechanism(s) on the efficiency of thermally controlled cell adhesion and release from poly­(<i>N</i>-isopropyl acrylamide) brushes. Large format polymer gradients were used to screen for grafting densities and substrate chemistries that alter both cell adhesion at 37 °C and rapid cell release at 25 °C. In particular, the grafting conditions investigated allowed protein adsorption to the underlying substrate, penetration of the brush only, or adsorption to the outer edge of the film. At an average molecular weight of 30 kDa (degree of polymerization <i>N</i> ∼ 270), the results show that robust protein adsorption to polymer brushes impairs rapid cell release below the lower critical solution temperature. Conversely, grafting conditions that permit protein penetration of the brush but block strong adsorption to the underlying substrate support cell adhesion above the transition temperature and ensure efficient cell recovery at lower temperature. These findings demonstrate the impact of protein adsorption mechanisms, surface chemistry, and polymer properties on thermally controlled cell capture and release

Design of a Quencher-Free Fluorescent Aptasensor for Ochratoxin A Detection in Red Wine Based on the Guanine-Quenching Ability

This study describes a quencher-free fluorescent aptasensor for ochratoxin A (OTA) detection using the specific quenching ability of guanine for fluorescein (FAM) molecules based on photo-induced electron transfer (PIET). In this strategy, OTA is detected by monitoring the fluorescence change induced by the conformational change of the aptamer after target binding. A new shorter OTA aptamer compromising three guanine bases at the 5&prime; end was used in this study. This new aptamer, named G3-OTAapt1-FAM (F1), was labeled with FAM on the 3&prime; end as a fluorophore. In order to increase the binding affinity of the aptamer and OTA, G3-OTAapt2-FAM (F2) was designed; this added a pair of complementary bases at the end compared with F1. To prevent the strong self-quenching of F2, a complementary chain, A13, was added. Although the F1 aptasensor was simpler to implement, the sensitivity of the F2 aptasensor with A13 was better than that of F1. The proposed F1 and F2 sensors can detect OTA with a concentration as low as 0.69 nmol/L and 0.36 nmol/L, respectively

Prioritizing conservation of biodiversity in an alpine region: Distribution pattern and conservation status of seed plants in the Qinghai-Tibetan Plateau

The Qinghai-Tibetan Plateau (QTP) harbors abundant and diverse plant life owing to its high habitat heterogeneity. However, the distribution pattern of biodiversity hotspots and their conservation status remain unclear. Based on 148,283 high-resolution occurrence coordinates of 13,450 seed plants, we identified hotspots by integrating data from species richness, species complementarity and spatial phylogenetics. Nine hotspot areas were identified that contained 89% of species but covered only 7% of the total land area of the QTP. Four of nine hotspots were identified firstly, including west Nyainqentanglha Mountains, the middle reaches of Lancang and Jinsha Rivers, the upper reaches of Yellow River and Qilian Mountains. Analysis of conservation efficiency indicated national nature reserves (NNRs) covered 55% of the hotspots, whereas NNRs and provincial nature reserves (PNRs) together protected 73% of the hotspots. Conservation efforts, such as establishing new protected areas and upgrading the level of existing nature reserves, should be strengthened in the conservation gaps. Targeted conservation should be carried out for species endemic to QTP due to their narrow distribution range and low conservation effectiveness. Niche modeling for 336 threatened plants indicated there were apparent range shifts of suitable habitat areas from the eastern edge to the center of the plateau under future climate scenarios, and conservation priority should be focused on the southern QTP for where have stable habitats