Natural interploidy hybridization among the key taxa involved in the origin of horticultural chrysanthemums

Understanding hybridization and introgression between natural plant populations can give important insights into the origins of cultivated species. Recent studies suggest differences in ploidy might not create such strong reproductive barriers as once thought, and thus studies into cultivated origins should examine all co-occurring taxa, including those with contrasting ploidy levels. Here, we characterized hybridization between Chrysanthemum indicum L., Chrysanthemum vestitum (Hemsley) Ling and Chrysanthemum vestitum var. latifolium (Zhou & Chen), the most important wild species involved in the origins of cultivated chrysanthemums. We analyzed the population structure of 317 Chrysanthemum accessions based on 13 microsatellite markers and sequenced chloroplast trnL-trnF for a subset of 103 Chrysanthemum accessions. We identified three distinct genetic clusters, corresponding to the three taxa. We detected 20 hybrids between species of different ploidy levels, of which 19 were between C. indicum (4x) and C. vestitum (6x) and one was between C. indicum and C. vestitum var. latifolium (6x). Fourteen hybrids between C. indicum and C. vestitum were from one of the five study sites. Chrysanthemum vestitum and C. vestitum var. latifolium share only one chloroplast haplotype. The substantially different number of hybrids between hybridizing species was likely due to different levels of reproductive isolation coupled with environmental selection against hybrids. In addition, human activities could play a role in the different patterns of hybridization among populations.     

Mapping and analysis of a spatiotemporal H3K27ac and gene expression spectrum in pigs

Science China Life Sciences - The limited knowledge of genomic noncoding and regulatory regions has restricted our ability to decipher the genetic mechanisms underlying complex traits in pigs. In...     

Effect of daily salinity fluctuation on the intraspecific interactions of a euhalophyte (Suaeda salsa) along a salinity gradient

每日盐度波动对真盐生植物盐地碱蓬种内相互作用沿盐度梯度的影响 土壤盐度的异质性是河口潮间带的一个突出的环境特征,影响植物的生长和盐沼中生物相互作用的转变。本研究旨在探究盐度梯度和盐度波动对一种真盐生植物的种内相互作用的交互影响。     

Effects of biodiversity,stand factors and functional identity on biomass and productivity during the restoration of subtropical forests in Central China

恢复梯度上华中亚热带森林生物多样性、林分因子及功能特性对生物量、生产力的影响 草地群落上进行的控制实验大都发现生物多样性对生态系统功能有显著促进作用。然而,在天然林中,多样性与林分因子、群落功能特性的相对作用大小仍存在争议。本文在森林恢复梯度上,研究这3类因素对生物量和生产力的相对影响。我们在湖北神农架设置了处于不同恢复阶段的24块(600 m²)亚热 带森林样地,计算了林分生物量和生产力。选择5个关键的植物功能性状,并计算了群落的功能多样性(功能丰富度、功能均匀度和功能离散度)和性状的加权平均值(CWM)。使用一般线性模型(GLMs)、变异分离等方法探究林分因子(密度、林龄、群落最大树高等)、功能特性、物种和功能多样性对生物量和生产力的相对重要性。研究结果表明,随着森林恢复,林分生物量和生产力显著增加,群落物种丰富度显著增加,而功能离散度显著降低。变异分离结果表明,多样性对生物量和生产力的单独效应不显著,但可能通过与林分因子和功能特性的协同效应来影响生物量和生产力。总体而言,我们发现林分因子对亚热带森林生物量和生产力的影响最大,功能特性显著影响生产力,但不影响生物量。这些结果说明,在森林经营中,调整林分结构和群落物种特性是提高森林碳储量和固碳潜力的有效途径。     

An efficient CRISPR/Cas9-based genome editing system for alkaliphilic Bacillus sp. N16-5 and application in engineering xylose utilization for D-lactic acid production

Alkaliphiles are considered more suitable chassis than traditional neutrophiles due to their excellent resistance to microbial contamination. Alkaliphilic Bacillus sp. N16-5, an industrially interesting strain with great potential for the production of lactic acid and alkaline polysaccharide hydrolases, can only be engineered genetically by the laborious and time-consuming homologous recombination. In this study, we reported the successful development of a CRISPR/Cas9-based genome editing system with high efficiency for single-gene deletion, large gene fragment deletion and exogenous DNA chromosomal insertion. Moreover, based on a catalytically dead variant of Cas9 (dCas9), we also developed a CRISPRi system to efficiently regulate gene expression. Finally, this efficient genome editing system was successfully applied to engineer the xylose metabolic pathway for the efficient bioproduction of D -lactic acid. Compared with the wild-type Bacillus sp. N16-5, the final engineered strain with XylR deletion and AraE overexpression achieved 34.3% and 27.7% increases in xylose consumption and D -lactic acid production respectively. To our knowledge, this is the first report on the development and application of CRISPR/Cas9-based genome editing system in alkaliphilic Bacillus, and this study will significantly facilitate functional genomic studies and genome manipulation in alkaliphilic Bacillus, laying a foundation for the development of more robust microbial chassis.     

Bacteriocins Produced by LAB Isolated from Cheeses within the Period 2009–2021: a Review

A survey is presented concerning original research articles published in well-reputed scientific journals on the isolation of lactic acid bacteria (LAB) from cheeses worldwide, where researchers evaluated the bacteriocin production by such isolates in searching for novel functional peptides that can exhibit potential for biotechnological applications. Seventy-one articles were published in the period of study, with contributions being American (45%), Asiatic (28%), and European (21%), being Brazil-USA-Mexico, Turkey-China, and France-Italy the countries that contributed the most for each said continent, respectively. Most of the isolated LAB belong to the genera Enterococcus (35%), Lactobacillus (30%), Lactococcus (14%), and Pediococcus (10%), coming from soft (64%), hard (27%), and semi-hard (9%) cheeses, predominantly. Also, scholars focused mainly on the food biopreservation (81%) and pharmaceutical field (18%) potential applications.

     

Effects of shear stress on 3-D human mesenchymal stem cell construct development in a perfusion bioreactor system: Experiments and hydrodynamic modeling

Shear stress is an important biomechanical parameter in regulating human mesenchymal stem cell (hMSC) construct development. In this study, the biomechanical characteristics of hMSCs within highly porous 3-D poly (ethylene terephthalate) (PET) matrices in a perfusion bioreactor system were analyzed for two flow rates of 0.1 and 1.5 mL/min, respectively over a 20-day culture period. A 1.4 times higher proliferation rate, higher CFU-F formation, and more fibronectin and HSP-47 secretion at day 20 were observed at the flow rate of 0.1 mL/min compared to those at the flow rate of 1.5 mL/min. The higher flow rate of 1.5 mL/min upregulated osteogenic differentiation potential at day 20 as measured by the expression of alkaline phosphatase activity and calcium deposition in the matrix after 14 days osteogenic induction, consistent with those reported in literatures. Mathematical modeling indicated that shear stress existed in the range of 1 x 10(-5) to 1 x 10(-4) Pa in the constructs up to a depth of 70 microm due to flow penetration in the porous constructs. Analysis of oxygen transport in the constructs for the two flow rates yielded oxygen levels significantly higher than those at which cell growth and metabolism are affected (Jiang et al., 1996). This indicates that differences in convective transport have no significant influence on cell growth and metabolism for the range of flow rates studied. These results demonstrate that shear stress is an important microenvironment parameter that regulates hMSC construct development at a range significantly lower than those reported previously in the perfusion system.     

Phylogenetic diversity of bacteria isolates from the Qinghai-Tibet Plateau permafrost region

The Qinghai-Tibet Plateau in east Asia is a unique and important permafrost environment. However, its microbiology remains largely unexplored to date. In this study, sediment samples were collected from the Qinghai-Tibet Plateau permafrost region, bacteria isolation procedures were performed 8 times, and the samples incubated at 4 degrees C for nearly 3 months. The number of colony forming units (cfu) ranged from 0 to 10(7)/(g dry soil). The quantity of culturable bacteria grew exponentially within the first few weeks, and then slowed gradually to a plateau. Phylogenetic analyses indicated that all the isolates fell into 6 categories: high G+C Gram-positive bacteria, low G+C Gram-positive bacteria, alpha-Proteobacteria, beta-Proteobacteria, gamma-Proteobacteria, and Cytophaga-Flavobacterium-Bacteroides group bacteria. The isolates belong to 19 genera, but the genera Arthrobacter and Pseudomonas were predominant. With the increase in incubation time, the isolated populations changed in terms of both species and their respective quantities. Of the 33 analyzed isolates, 9 isolates related to 8 genera might be new taxa. These results suggest that the Qinghai-Tibet Plateau permafrost region is a specific ecologic niche that accommodates an original microbial assemblage.     

Virulence potential and genetic diversity of Aeromonas caviae, Aeromonas veronii, and Aeromonas hydrophila clinical isolates from Mexico and Spain: a comparative study

A comparative study of 109 Aeromonas clinical isolates belonging to the 3 species most frequently isolated from patients with diarrhea in Mexico and Spain was performed to investigate the distribution of 3 prominent toxin genes and the gene encoding flagellin of lateral flagella; 4 well-established virulence factors in the genus Aeromonas. The aerolysin-hemolysin toxin genes were the most prevalent, being present in 89% of the total isolates. The ast toxin gene was conspicuously absent from the Aeromonas caviae and Aeromonas veronii groups but was present in 91% of the Aeromonas hydrophila isolates. Both the alt toxin gene and the lafA flagellin gene also had a low incidence in A. caviae and A. veronii. Differences in the prevalence of alt and lafA were observed between isolates from Mexico and Spain, confirming genus heterogeneity according to geographic location. Carriage of multiple toxin genes was primarily restricted to A. hydrophila isolates, suggesting that A. caviae and A. veronii isolates circulating in Mexico and Spain possess a limited array of virulence genes. Enterobacterial repetitive intergenetic consensus - polymerase chain reaction showed that the Aeromonas populations sampled lack dominant clones and were genetically heterogeneous, with A. caviae being the most diverse species. Further surveys of virulence determinants in genetically heterogeneous populations of Aeromonas isolates circulating worldwide are required to enhance the understanding of their capacity to cause disease.