The EPSPS gene flow from glyphosate-resistant Brassica napus to untransgene B. napus and wild relative species Orychophragmus violaceus

Gene flow from transgenic plants to compatible wild relatives is one of the major impediments to the development of the culture of genetically engineered crop plants. In this work, the flow of EPSPS (conferring resistance to glyphosate) gene of transgene Brassica napus toward the untransgene B. napus and wild relative species Orychophragmus violaceus in an open field (1 ha) was studied. The data related to only the 2004 and 2005 autumn season on one location of southwest of China. Pollen dispersal and fertilization of the target plants were favored and a detailed analysis of the hybrid offspring was performed. In field, the data studied show that the gene flow frequency was 0.16% between GM and non-GM B. napus at a distance of 1 m from the transgenic donor area. The crosspollination frequency was 0.05% between GM and non-GM B. napus at a distance of 5 m from the transgenic donor area. At a distance of 10 m, no crosspollination was observed. According to the results of this study, B. napus transgene flow was low. However, the wild relative species O. violaceus could not be fertilized by the transgenic pollen of B. napus, no matter what the distance was.     

Viral tegument proteins restrict cGAS-DNA phase separation to mediate immune evasion

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Bioactive thin film of acidic fibroblast growth factor fabricated by layer-by-layer assembly

A new class of bioactive thin films using growth factors as building blocks has been fabricated via layer-by-layer assembly (LBL) technique. Acid fibroblast growth factor (aFGF) in the presence of heparin was used as negatively charged polyelectrolytes, while poly(ethyleneimine) (PEI) was chosen as a positively charged counterpart. The self-deposition process and surface morphology of the resultant multilayers were monitored and detected by UV-vis absorbance spectra, advanced contact angle measurements, and scanning force microscopy (SFM) observations. Cell culture was performed to assess the efficiency of the growth factors. The fibroblasts proliferated faster on the surface assembled with five bilayers of (aFGF/heparin)/PEI with apparent higher cytoviability than on those surfaces modified by one bilayer of (aFGF/heparin)/PEI, five bilayers of aFGF/PEI, or five bilayers of heparin/PEI, and tissue culture polystyrene. Enhanced secretion of collagen type I and interleukin 6 (IL-6) by the fibroblasts seeded on the five bilayers of (aFGF/heparin)/PEI was also verified by immunohistochemical examination. The bioactivity of the (aFGF/heparin)/PEI multilayers could be largely preserved when stored at -20 degrees C.     

High-quality genome assembly of Huazhan and Tianfeng,the parents of an elite rice hybrid Tian-you-hua-zhan

High-quality rice reference genomes have accelerated the comprehensive identification of genome-wide variations and research on functional genomics and breeding. Tian-you-hua-zhan has been a leading hybrid in China over the past decade. Here, de novo genome assembly strategy optimization for the rice indica lines Huazhan (HZ) and Tianfeng (TF), including sequencing platforms, assembly pipelines and sequence depth, was carried out. The PacBio and Nanopore platforms for long-read sequencing were utilized, with the Canu, wtdbg2, SMARTdenovo, Flye, Canu-wtdbg2, Canu-SMARTdenovo and Canu-Flye assemblers. The combination of PacBio and Canu was optimal, considering the contig N50 length, contig number, assembled genome size and polishing process. The assembled contigs were scaffolded with Hi-C data, resulting in two “golden quality” rice reference genomes, and evaluated using the scaffold N50, BUSCO, and LTR assembly index. Furthermore, 42,625 and 41,815 non-transposable element genes were annotated for HZ and TF, respectively. Based on our assembly of HZ and TF, as well as Zhenshan97, Minghui63, Shuhui498 and 9311, comprehensive variations were identified using Nipponbare as a reference. The de novo assembly strategy for rice we optimized and the “golden quality” rice genomes we produced for HZ and TF will benefit rice genomics and breeding research, especially with respect to uncovering the genomic basis of the elite traits of HZ and TF.

     

QCM detection of DNA targets with single-base mutation based on DNA ligase reaction and biocatalyzed deposition amplification

A novel biosensing technique for highly specific identification of gene with single-base mutation is proposed based on the implementation of the DNA ligase reaction and the biocatalyzed deposition of an insoluble product. The target gene mediated deposition of an insoluble precipitate is then transduced by quartz crystal microbalance (QCM) measurements. In this method, the DNA target hybridizes with a capture DNA probe tethered onto the gold electrode and then with a biotinylated allele-specific detection DNA. A ligase reaction is performed to generate the ligation between the capture and the detection probes, provided there is perfect match between the DNA target and the detection probe. Otherwise even when there is an allele mismatch between them, no ligation would take place. After thermal treatment at an elevated temperature, the formed duplex melts apart that merely allows the detection probe perfectly matched with the target to remain on the electrode surface. The presence of the biotinylated allele-matched probe is then detected by the QCM via the binding to streptavidin-peroxide horseradish (SA-HRP), which catalyzes the oxidative precipitation of 3,3-diaminobenzidine (DAB) by H2O2 on the electrode and provides an amplified frequency response. The proposed approach has been successfully implemented for the identification of single-base mutation in -28 site of the beta-thalassemia gene with a detection limit of 0.1 nM, demonstrating that this method provides a highly specific and cost-efficient approach for point mutation detection.     

浙江建德青冈常绿阔叶林凋落量研究

 本文报道了浙江建德青冈常绿阔叶林的凋落量及各类凋落物的凋落特征。 6年的测定结果表明,青冈林的年均凋落量为5547.6kg/(hm2·a),其中枯叶量占68.32%,枯枝、落果、其它凋落物各占14.82%、15.04%和1.82%。各类凋落量具有明显的季节与年际变化规律,其季节分配还具年际波动现象。各类凋落物的凋落特征从一定角度反映了植物群落一般的生物学与生态学特性,以及植物对特殊环境条件的适应性。     

Genetic Analyses of the Internal Transcribed Spacer Sequences Suggest Introgression and Duplication in the Medicinal Mushroom Agaricus subrufescens

The internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene cluster is widely used in fungal taxonomy and phylogeographic studies. The medicinal and edible mushroom Agaricus subrufescens has a worldwide distribution with a high level of polymorphism in the ITS region. A previous analysis suggested notable ITS sequence heterogeneity within the wild French isolate CA487. The objective of this study was to investigate the pattern and potential mechanism of ITS sequence heterogeneity within this strain. Using PCR, cloning, and sequencing, we identified three types of ITS sequences, A, B, and C with a balanced distribution, which differed from each other at 13 polymorphic positions. The phylogenetic comparisons with samples from different continents revealed that the type C sequence was similar to those found in Oceanian and Asian specimens of A. subrufescens while types A and B sequences were close to those found in the Americas or in Europe. We further investigated the inheritance of these three ITS sequence types by analyzing their distribution among single-spore isolates from CA487. In this analysis, three co-dominant markers were used firstly to distinguish the homokaryotic offspring from the heterokaryotic offspring. The homokaryotic offspring were then analyzed for their ITS types. Our genetic analyses revealed that types A and B were two alleles segregating at one locus ITSI, while type C was not allelic with types A and B but was located at another unlinked locus ITSII. Furthermore, type C was present in only one of the two constitutive haploid nuclei (n) of the heterokaryotic (n+n) parent CA487. These data suggest that there was a relatively recent introduction of the type C sequence and a duplication of the ITS locus in this strain. Whether other genes were also transferred and duplicated and their impacts on genome structure and stability remain to be investigated.