Genetic Engineering for Breeding for Drought Resistance and Salt Tolerance in Agropyron Spp. (Wheatgrass)

Genetic engineering for breeding for drought resistance and salt tolerance in wheatgrass, lucerne and tall fescue is one of the main projects in a major national programs as part of the10th’five-year national plan: “Research of gene transfer in plants and its industrialisation”. It is a large project that has financial support for work on forage crops in China and many research institutes and universities take part in it. The Inner Mongolia Agricultural University is in charge of the project on wheatgrass. The research was started in Nov. 2002. The general situation and the primary results are introduced and summarised in this paper

Origin of Scaling Behavior of Protein Packing Density: A Sequential Monte Carlo Study of Compact Long Chain Polymers

Single domain proteins are thought to be tightly packed. The introduction of voids by mutations is often regarded as destabilizing. In this study we show that packing density for single domain proteins decreases with chain length. We find that the radius of gyration provides poor description of protein packing but the alpha contact number we introduce here characterize proteins well. We further demonstrate that protein-like scaling relationship between packing density and chain length is observed in off-lattice self-avoiding walks. A key problem in studying compact chain polymer is the attrition problem: It is difficult to generate independent samples of compact long self-avoiding walks. We develop an algorithm based on the framework of sequential Monte Carlo and succeed in generating populations of compact long chain off-lattice polymers up to length $N=2,000$. Results based on analysis of these chain polymers suggest that maintaining high packing density is only characteristic of short chain proteins. We found that the scaling behavior of packing density with chain length of proteins is a generic feature of random polymers satisfying loose constraint in compactness. We conclude that proteins are not optimized by evolution to eliminate packing voids.Comment: 9 pages, 10 figures. Accepted by J. Chem. Phy

Bibliometric analysis of research on secondary organic aerosols: A Science Citation Index Expanded-based analysis (IUPAC Technical Report)

This study was conceived to evaluate the global scientific output of secondary organic aerosol (SOA) research over the past 20 years and to assess the characteristics of the research patterns, tendencies, and methods in the papers. Data were based on the online version of Science Citation Index Expanded from 1992 to 2011. Publications referring to SOAs were assessed by distribution of the number of publications and times cited, source categories, source journals, author keywords, Key Words Plus, and the most cited publications in these years. By synthetic analysis of author keywords, Key Words Plus, titles, and abstracts, it was concluded that modeling is currently and will at least over the next decade continue to be the predominant research method to validate state-of-the-art knowledge of SOAs, and that the foci of SOA research will be the key precursors terpenes and isoprene, the mechanisms of oxidation and gas-phase reactions, and emission inventories

Non-parametric Kernel Ranking Approach for Social Image Retrieval

National Research Foundation (NRF) Singapore; Ministry of Education, Singapore under its Academic Research Funding Tier

A Two-View Learning Approach for Image Tag Ranking

Singapore Ministry of Education Academic Research Fund Tier

The Role of Tryptophan in π Interactions in Proteins:An Experimental Approach

In proteins, the amino acids Phe, Tyr, and especially Trp are frequently involved in π interactions such as π-π, cation-π, and CH-π bonds. These interactions are often crucial for protein structure and protein-ligand binding. A powerful means to study these interactions is progressive fluorination of these aromatic residues to modulate the electrostatic component of the interaction. However, to date no protein expression platform is available to produce milligram amounts of proteins labeled with such fluorinated amino acids. Here, we present a Lactococcus lactis Trp auxotroph-based expression system for efficient incorporation (≥95%) of mono-, di-, tri-, and tetrafluorinated, as well as a methylated Trp analog. As a model protein we have chosen LmrR, a dimeric multidrug transcriptional repressor protein from L. lactis. LmrR binds aromatic drugs, like daunomycin and riboflavin, between Trp96 and Trp96' in the dimer interface. Progressive fluorination of Trp96 decreased the affinity for the drugs 6- to 70-fold, clearly establishing the importance of electrostatic π-π interactions for drug binding. Presteady state kinetic data of the LmrR-drug interaction support the enthalpic nature of the interaction, while high resolution crystal structures of the labeled protein-drug complexes provide for the first time a structural view of the progressive fluorination approach. The L. lactis expression system was also used to study the role of Trp68 in the binding of riboflavin by the membrane-bound riboflavin transport protein RibU from L. lactis. Progressive fluorination of Trp68 revealed a strong electrostatic component that contributed 15-20% to the total riboflavin-RibU binding energy

Preparation and characterisation of manganese, cobalt and zinc DNA nanoflowers with tuneable morphology, DNA content and size

Recently reported DNA nanoflowers are an interesting class of organic-inorganic hybrid materials which are prepared using DNA polymerases. DNA nanoflowers combine the high surface area and scaffolding of inorganic Mg2P2O7 nanocrystals with the targeting properties of DNA, whilst adding enzymatic stability and enhanced cellular uptake. We have investigated conditions for chemically modifying the inorganic core of these nanoflowers through substitution of Mg2+ with Mn2+, Co2+ or Zn2+ and have characterised the resulting particles. These have a range of novel nanoarchitectures, retain the enzymatic stability of their magnesium counterparts and the Co2+ and Mn2+ DNA nanoflowers have added magnetic properties. We investigate conditions to control different morphologies, DNA content, hybridisation properties, and size. Additionally, we show that DNA nanoflower production is not limited to Ф29 DNA polymerase and that the choice of polymerase can influence the DNA length within the constructs. We anticipate that the added control of structure, size and chemistry will enhance future application