Correction to: Description of desferrioxamine-producing bacterium Chitinophaga agrisoli sp. nov., isolated from soil

Antonie van Leeuwenhoek -     

Modeling bioaffinity-based targeted delivery of antimicrobials to Escherichia coli biofilms using yeast microparticles. Part II: Parameter evaluation and validation

The design of bioaffinity-based targeted delivery systems for biofilm inactivation may require a comprehensive understanding of physicochemical and biochemical properties of biobased antimicrobial particles and their interactions with biofilm. In this study, Escherichia coli biofilm inactivation by chlorine-charged yeast microparticles was numerically simulated, and the roles of chemical stability, binding affinity, and controlled release of this targeted delivery system were assessed using this numerical simulation. The simulation results were experimentally validated using two different types of yeast microparticles. The results of this study illustrate that chorine stability achieved by yeast microparticles was a key factor for improved biofilm inactivation in an organic-rich environment (>6 additional log reduction in 20 min compared to the free chlorine treatment). Moreover, the binding affinity of yeast microparticles to E. coli biofilms was another key factor for an enhanced inactivation of biofilm, as a 10-fold increase in binding rate resulted in a 4.2-fold faster inactivation. Overall, the mechanistic modeling framework developed in this study could guide the design and development of biobased particles for targeted inactivation of biofilms.     

铜绿假单胞菌对青霉素类抗生素异质性耐药研究

【背景】铜绿假单胞菌是临床上常见的条件致病菌,其异质性耐药的发生常导致临床治疗失败。【目的】研究铜绿假单胞菌对青霉素类抗生素的异质性耐药情况,为相关临床感染治疗提供一定的依据。【方法】收集临床分离的50株铜绿假单胞菌,采用纸片扩散法(diskdiffusion method)即Kirby-Bauer (K-B)法、菌落谱型分析(population analysis profile,PAP)法、生长实验以及传代稳定性实验探究铜绿假单胞菌的异质性耐药特征。【结果】K-B法初筛得到铜绿假单胞菌对哌拉西林(piperacillin,PIP)、哌拉西林/他唑巴坦(piperacillin/tazobactam,TZP)和替卡西林/克拉维酸(ticarcillin/clavulanic acid,TIM)的异质性耐药率分别为52%、52%和54%。PAP实验确认后有13株异质性耐药菌,其检出率占总实验菌株的26%。随机选取8株异质性耐药菌株,其耐药亚群的发生频率为7.3×10-7-1.2×10-5。通过无抗生素压力的生长实验发现,异质性耐药菌株PAS92、PAS57与其各自的3株最高PIP浓度平...     

耐镉促生菌株的分离鉴定及对大豆的促生效应

【背景】华南地区镉（Cd）污染严重,与有益微生物共生能够使作物通过直接或间接的机制解除镉毒,提高抗逆性,进而促进生长。耐镉促生菌剂具有广泛的应用前景。【目的】从华南地区受镉污染植株的根内和根际筛选出耐镉且能促进大豆生长的促生菌,以丰富促进田间大豆生产的优异菌种资源。【方法】采用平板划线法从植株的根内或根际分离菌株,通过生理生化特性和16S rRNA基因序列分析对分离菌株进行初步研究,利用盆栽试验探究镉胁迫下菌株对大豆生长的影响,通过测定丙二醛含量和总抗氧化能力探究菌株的耐镉机制。【结果】分离获得4株菌D1、D2、D3和D4,促生特性试验证明4株菌均具有溶磷、产吲哚乙酸和铁载体的能力。经16S rRNA基因序列分析鉴定,D1、D2、D3和D4菌株分别属于不动杆菌属、微小杆菌属、类芽孢杆菌属和普罗威登斯菌属。用这4株菌进行不同镉处理的大豆（巴西10号）盆栽试验,结果表明,4株菌均具有耐镉和促进大豆生长的作用。不添加镉的条件下,大豆接种D4菌株的地上部干重、根部干重和株高分别增加了28%、35%和31%;在添加20mg/kg-CdCl₂·5/2H₂...     

Arbuscular Mycorrhizal Fungus and Exogenous Potassium Application Improved Lycium barbarum Salt Tolerance

Journal of Plant Growth Regulation - Salt stress is one of the major abiotic stress, impedes plant photosynthetic processes, changes root architecture to impact leaf water status, and reduces...     

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.

     

Light from heat lamps affects sow behaviour and piglet salivary melatonin levels

The light environment regulates animal physiology and behaviour. As widely used supplementary heat sources in creep areas, the effect of visible light radiated by infrared heat lamps on pigs is worth investigating. To investigate the effects of light from heat lamps on the behaviour of sows and piglets and possible endocrine mechanisms, 24 primiparous sows were randomly assigned to three supplementary heat source treatments: (1) 250 W non-luminous ceramic heat lamps (CE, n = 8), (2) 175 W red heat lamps (RL, n = 8), and (3) 175 W transparent heat lamps (TL, n = 8). All heat lamps were turned off on Day 15 postpartum. Piglets were weighed on days 3 and 21 postpartum. The number and duration of suckling within 24 h were analysed via video recordings on days 4, 8, and 16 postpartum. Sow posture changes during the day and night were detected using the YOLOv4 target detection network model. One marked piglet from six litters randomly selected from each treatment was used for saliva collection. Saliva samples were collected at 0800, 1400, 2000, and 0200 (+1 d) on days 10 and 20 postpartum. The results showed that the mean postural change frequency of TL sows was higher than that of CE sows (P < 0.05), while that of RL sows was not different from that of CE and TL sows. However, the duration of the sows being in each posture was not affected by the treatment. The total suckling duration of TL piglets was significantly longer than that of CE piglets, but there was no significant difference in the performance of the piglets. The melatonin concentrations in the saliva of piglets at 10 and 20 days of age in the three treatments showed different diurnal rhythms, but there was no significant difference in the levels of melatonin in TL piglets between night and day. Differences in salivary cortisol levels only appeared between the CE and RL groups at 20 days of age. Based on the present results, the illuminance and spectrum of the transparent heat lamps were sufficient to stimulate sow activity and inhibit melatonin levels in piglets. However, the stimulating effect on suckling was not sufficient to significantly improve the performance of piglets. Exposure to red heat lamps, rather than ceramic lamps, resulted in the strongest circadian rhythm of salivary melatonin in piglets.     

Chronic social defeat stress-induced enhancement of T-type calcium channels increases burst-firing neurons in the ventral subiculum

The ventral subiculum (vSub), a representative output structure of the hippocampus, serves as a main limbic region in mediating the brain's response to stress. There are three subtypes of subicular pyramidal neurons based on their firing patterns: regular-spiking (RS), weak-bursting (WB) and strong-bursting (SB) neurons, located differently along proximal–distal axis. Here, we found that chronic social defeat stress (CSDS) in mice increased the population of SB neurons but decreased RS neurons in the proximal vSub. Specific blockers of T-type calcium channels inhibited the burst firings with a concomitant reduction of afterdepolarization, suggesting that T-type calcium channels underlie the burst-spiking activity. Consistently, CSDS increased both T-type calcium currents and expression of Cav3.1 proteins, a subtype of T-type calcium channels, in the proximal vSub. Therefore, we conclude that CSDS-induced enhancement of Cav3.1 expression increased bursting neuronal population in the vSub, which may contribute to stress-related behaviors.     

ULK1 negatively regulates Wnt signaling by phosphorylating Dishevelled

Wnt signaling pathway plays critical roles in body axes patterning, cell fate specification, cell proliferation, cell migration, stem cell maintenance, cancer development and etc. Deregulation of this pathway can be causative of cancer, metabolic disease and neurodegenerative disease such as Parkinson`s disease. Among the core components of Wnt signaling pathway, we discovered that Dishevelled (Dsh) interacts with ULK1 and is phosphorylated by ULK1. Unexpectedly, the knockdown of ULK1 elicited a marked increase in Wnt/β-catenin signaling. Multiple ULK1 phosphorylation sites existed on Dsh and many of them were located on the PDZ-DEP region. By using evolutionarily well conserved Drosophila Dsh, we found that S239, S247 and S254 in the PDZ-DEP region are involved in phosphorylation of Dsh by ULK1. Among these, S247 and S254 were conserved in human Dsh. When phospho-mimetic mutants (2D and 2E Dsh mutants) of these conserved residues were generated and expressed in the eyes of the fruit flies, the activity of Dsh was significantly decreased compared to wild type Dsh. Through additional alanine scanning, we further identified that S239, S247, S254, S266, S376, S554 and S555 on full length Dsh were phosphorylated by ULK1. In regards to the S266A mutation located in the PDZ domain among these phosphorylated residues, our results suggested that Dsh forms an SDS-resistant high molecular weight complex with β-catenin and TCF in the nucleus in an S266 phosphorylation-dependent manner. Based on these results, we propose that ULK1 plays a pivotal role in the regulation of Wnt/β-catenin signaling pathway by phosphorylating Dsh.