Proximity association in polygynous western black crested gibbons (Nomascus concolor jingdongensis): network structure and seasonality

We investigated the structure and seasonality of the proximity network in a group of polygynous western black crested gibbons (Nomascus concolor) using social network analysis. The spatial proximity changed seasonally and was affected by temperature and rainfall. Preferred proximity association was not distributed randomly among individuals. Kinship was one explanation for the social structure, as offspring preferred to maintain close proximity with their mothers. The proximity of infants to mothers decreased with age, and independent offspring had lower proximity to mothers than dependent ones. We found that the adult male had different proximity relationships with two different adult females. The frequency of proximity between the male and the infant-carrying female was significantly higher than that between the male and the female who had immigrated carrying one offspring of uncertain paternity into the group. Infanticide avoidance and/or predation protection for dependent infants might explain the proximity relationship differences. Temperature influenced group proximity association, with individual proximity increasing in the cold months and decreasing in the hot months. Group proximity decreased in months with higher anthropogenic disturbance.     

Structural and functional analyses of catalytic domain of GH10 xylanase from Thermoanaerobacterium saccharolyticum JW/SL‐YS485

Xylanases are capable of decomposing xylans, the major components in plant cell wall, and releasing the constituent sugars for further applications. Because xylanase is widely used in various manufacturing processes, high specific activity, and thermostability are desirable. Here, the wild‐type and mutant (E146A and E251A) catalytic domain of xylanase from Thermoanaerobacterium saccharolyticum JW/SL‐YS485 (TsXylA) were expressed in Escherichia coli and purified subsequently. The recombinant protein showed optimal temperature and pH of 75°C and 6.5, respectively, and it remained fully active even after heat treatment at 75°C for 1 h. Furthermore, the crystal structures of apo‐form wild‐type TsXylA and the xylobiose‐, xylotriose‐, and xylotetraose‐bound E146A and E251A mutants were solved by X‐ray diffraction to high resolution (1.32–1.66 Å). The protein forms a classic (β/α)₈ folding of typical GH10 xylanases. The ligands in substrate‐binding groove as well as the interactions between sugars and active‐site residues were clearly elucidated by analyzing the complex structures. According to the structural analyses, TsXylA utilizes a double displacement catalytic machinery to carry out the enzymatic reactions. In conclusion, TsXylA is effective under industrially favored conditions, and our findings provide fundamental knowledge which may contribute to further enhancement of the enzyme performance through molecular engineering. Proteins 2013; 81:1256–1265. © 2013 Wiley Periodicals, Inc.     

Influence of solids retention time on membrane fouling: characterization of extracellular polymeric substances and soluble microbial products

The objective of this study was to investigate the influence of solids retention time (SRT) on membrane fouling and the characteristics of biomacromolecules. Four identical laboratory-scale membrane bioreactors (MBRs) were operated with SRTs for 10, 20, 40 and 80 days. The results indicated that membrane fouling occurred faster and more readily under short SRTs. Fouling resistance was the primary source of filtration resistance. The modified fouling index (MFI) results suggested that the more ready fouling at short SRTs could be attributed to higher concentrations of soluble microbial products (SMP). Fourier transform infrared (FTIR) spectra indicated that the SRT had a weak influence on the functional groups of the total extracellular polymeric substances (TEPS) and SMP. However, the MBR under a short SRT had more low-molecular-weight (MW) compounds (<1 kDa) and fewer high-MW compounds (>100 kDa). Aromatic protein and tryptophan protein-like substances were the dominant groups in the TEPS and SMP, respectively.     

Structure and function of the CBL–CIPK Ca2+-decoding system in plant calcium signaling

Calcium is a crucial messenger in many growth and developmental processes in plants. The central mechanism governing how plant cells perceive and respond to environmental stimuli is calcium signal transduction, a process through which cellular calcium signals are recognized, decoded, and transmitted to elicit downstream responses. In the initial decoding of calcium signals, Ca²⁺ sensor proteins that bind Ca²⁺ and activate downstream signaling components are implicated, thereby regulating specific physiological and biochemical processes. After calcineurin B-like proteins (CBLs) sense these Ca²⁺ signatures, these proteins interact selectively with CBL-interacting protein kinases (CIPKs), thereby forming CBL/CIPK complexes, which are involved in decoding calcium signals. Therefore, specificity, diversity, and complexity are the main characteristics of the CBL-CIPK signaling system. However, additional CBLs, CIPKs, and CBL/CIPK complexes remain to be identified in plants, and the specific functions of their abiotic and biotic stress signaling will need to be further dissected. Therefore, a much-needed synthesis of recent findings is important to further the study of CBL-CIPK signaling systems. Here, we review the structure of CBLs and CIPKs, discuss the current knowledge of CBL–CIPK pathways that decode calcium signals in Arabidopsis, and link plant responses to a variety of environmental stresses with specific CBL/CIPK complexes. This will provide a foundation for future research on genetically engineered resistant plants with enhanced tolerance to various environmental stresses.     

Multifaceted applications of nanomaterials in cell engineering and therapy

Nanomaterials with superior physiochemical properties have been rapidly developed and integrated in every aspect of cell engineering and therapy for translating their great promise to clinical success. Here we demonstrate the multifaceted roles played by innovatively-designed nanomaterials in addressing key challenges in cell engineering and therapy such as cell isolation from heterogeneous cell population, cell instruction in vitro to enable desired functionalities, and targeted cell delivery to therapeutic sites for prompting tissue repair. The emerging trends in this interdisciplinary and dynamic field are also highlighted, where the nanomaterial-engineered cells constitute the basis for establishing in vitro disease model; and nanomaterial-based in situ cell engineering are accomplished directly within the native tissue in vivo. We will witness the increasing importance of nanomaterials in revolutionizing the concept and toolset of cell engineering and therapy which will enrich our scientific understanding of diseases and ultimately fulfill the therapeutic demand in clinical medicine.     

Mechanistic studies of perfluorooctane sulfonate, perfluorooctanoic acid uptake by maize (Zea mays L. cv. TY2)

Aims

There is a need to predict trace metal concentration in plant organs at given development stages. The aim of this work was to describe the Cd hyperaccumulation kinetics in the different plant organs, throughout the complete cultivation cycle, independently of a possible soil effect.

Methods

Plants of Noccaea caerulescens were exposed in aeroponics to three constantly low Cd concentrations and harvested at 6 to 11 dates, until siliquae formation.

Results

Dry matter allocation between roots and shoots was constant over time and exposure concentrations, as well as Cd allocation. However 86 % of the Cd taken up was allocated to the shoots. Senescent rosette leaves showed similar Cd concentrations to the living ones, suggesting no redistribution from old to young organs. The Cd root influx was proportional to the exposure concentration and constant over time, indicating that plant development had no effect on this. The bio-concentration factor (BCF), i.e. [Cd]_plant/[Cd²⁺]_solution for the whole plant, roots or shoots was independent of the exposure concentration and of the plant stage.

Conclusions

Cadmium uptake in a given plant part could therefore be predicted at any plant stage by multiplying the plant part dry matter by the corresponding BCF and the Cd²⁺ concentration in the exposure solution.