ALBERT

Description: Author(s): Cuong Cao Vu, Shoumo Zhang, Michael Urbakh, Qunyang Li, Q.-C. He, and Quanshui Zheng We investigate the dependence of friction forces on normal load in incommensurate micrometer-size contacts between atomically smooth single-crystal graphite surfaces under ambient conditions. Our experimental results show that these contacts exhibit superlubricity (superlow friction), which is robus… [Phys. Rev. B 94, 081405(R)] Published Fri Aug 05, 2016

Description: This study aimed to investigate the effects of dietary fibre sources on the gut microbiota in suckling piglets, and to test the hypothesis that a moderate increase of dietary fibre may affect the gut microbiota during the suckling period. Suckling piglets were fed different fibre-containing diets or a control diet from postnatal day 7 to 22. Digesta samples from cecum, proximal colon and distal colon were used for Pig Intestinal Tract Chip analysis. The data showed that the effects of fibre-containing diet on the gut microbiota differed in the fibre source and gut location. The alfalfa diet increased Clostridium cluster XIVb and Sporobacter termitidis in the cecum compared to the pure cellulose diet. Compared to the control diet, the alfalfa diet also increased Coprococcus eutactus in the distal colon, while the pure cellulose diet decreased Eubacterium pyruvativorans in the cecum. The pure cellulose diet increased Prevotella ruminicola compared to the wheat bran diet. Interestingly, the alfalfa group had the lowest abundance of the potential pathogen Streptococcus suis in the cecum and distal colon. These results indicated that a moderate increase in dietary fibres affected the microbial composition in suckling piglets, and that the alfalfa inclusion produced some beneficial effects on the microbial communities.

Description: The microbial fermentation process is one of the sustainable and environment-friendly ways to produce 1-butanol and other bio-based chemicals. The success of the fermentation process greatly relies on the choice of bioreactors and the separation methods. In this review, the history and the performance of bioreactors for the acetone–butanol–ethanol (ABE) fermentation is discussed. The subject is then focused on in situ product recovery (ISPR) techniques, particularly for the integrated extraction-gas stripping. The usefulness of this promising hybrid ISPR device is acknowledged by its incorporation with batch, fed-batch and continuous processes to improve the performance of ABE fermentation.

Description: Gene loss is the driving force for changes in genome and morphology; however, this particular evolutionary event has been poorly investigated in leguminous plants. Legumes (Fabaceae) have some lineage-specific and diagnostic characteristics that are distinct from other angiosperms. To understand the potential role of gene loss in the evolution of legumes, we compared six genome-sequenced legume species of Papilionoideae, the largest representative clade of Fabaceae, such as Glycine max , with 34 nonlegume plant species, such as Arabidopsis thaliana . The results showed that the putative orthologs of the 34 Arabidopsis genes belonging to 29 gene families were absent in these legume species but these were conserved in the sequenced nonlegume angiosperm lineages. Further evolutionary analyses indicated that the orthologs of these genes were almost completely lost in the Papillionoideae ancestors, thus designated as the legume lost genes (LLGs), and these underwent purifying selection in nonlegume plants. Most LLGs were functionally unknown. In Arabidopsis , two LLGs were well-known genes that played a role in plant immunity such as HARMLESS TO OZONE LAYER 1 and HOPZ-ACTIVATED RESISTANCE 1 , and 16 additional LLGs were predicted to participate in plant–pathogen interactions in in silico expression and protein–protein interaction network analyses. Most of these LLGs’ orthologs in various plants were also found to be associated with biotic stress response, indicating the conserved role of these genes in plant defense. The evolutionary implication of LLGs during the development of the ability of symbiotic nitrogen fixation involving plant and bacterial interactions, which is a well-known characteristic of most legumes, is also discussed. Our work sheds light on the evolutionary implication of gene loss events in Papilionoideae evolution, as well as provides new insights into crop design to improve nitrogen fixation capacity.

Description: Author(s): D. Springer, Saritha K. Nair, Mi He, C. L. Lu, S. A. Cheong, T. Wu, C. Panagopoulos, Elbert E. M. Chia, and Jian-Xin Zhu The temperature dependence of the relaxation dynamics in the bilayer thin film heterostructure composed of multiferroic BiFeO 3 (BFO) and superconducting YBa 2 Cu 3 O 7 (YBCO) grown on a (001) SrTiO 3 substrate is studied by a time-resolved pump-probe technique, and compared with that of pure YBCO thin fil… [Phys. Rev. B 93, 064510] Published Fri Feb 12, 2016

Description: Ten Eleven Translocation (TET) protein-catalyzed 5mC oxidation not only creates novel DNA modifications, such as 5hmC, but also initiates active or passive DNA demethylation. TETs’ role in the crosstalk with specific histone modifications, however, is largely elusive. Here, we show that TET2-mediated DNA demethylation plays a primary role in the de novo establishment and maintenance of H3K4me3/H3K27me3 bivalent domains underlying methylated DNA CpG islands (CGIs). Overexpression of wild type (WT), but not catalytic inactive mutant (Mut), TET2 in low-TET-expressing cells results in an increase in the level of 5hmC with accompanying DNA demethylation at a subset of CGIs. Most importantly, this alteration is sufficient in making de novo bivalent domains at these loci. Genome-wide analysis reveals that these de novo synthesized bivalent domains are largely associated with a subset of essential developmental gene promoters, which are located within CGIs and are previously silenced due to DNA methylation. On the other hand, deletion of Tet1 and Tet2 in mouse embryonic stem (ES) cells results in an apparent loss of H3K27me3 at bivalent domains, which are associated with a particular set of key developmental gene promoters. Collectively, this study demonstrates the critical role of TET proteins in regulating the crosstalk between two key epigenetic mechanisms, DNA methylation and histone methylation (H3K4me3 and H3K27me3), particularly at CGIs associated with developmental genes.

Description: Forkhead box A1 (FOXA1) is an FKHD family protein that plays pioneering roles in lineage-specific enhancer activation and gene transcription. Through genome-wide location analyses, here we show that FOXA1 expression and occupancy are, in turn, required for the maintenance of these epigenetic signatures, namely DNA hypomethylation and histone 3 lysine 4 methylation. Mechanistically, this involves TET1, a 5-methylcytosine dioxygenase. We found that FOXA1 induces TET1 expression via direct binding to its cis-regulatory elements. Further, FOXA1 physically interacts with the TET1 protein through its CXXC domain. TET1 thus co-occupies FOXA1-dependent enhancers and mediates local DNA demethylation and concomitant histone 3 lysine 4 methylation, further potentiating FOXA1 recruitment. Consequently, FOXA1 binding events are markedly reduced following TET1 depletion. Together, our results suggest that FOXA1 is not only able to recognize but also remodel the epigenetic signatures at lineage-specific enhancers, which is mediated, at least in part, by a feed-forward regulatory loop between FOXA1 and TET1.