Whole-genome sequencing of allotetraploid bermudagrass reveals the origin of Cynodon and candidate genes for salt tolerance.

Bermudagrass (Cynodon dactylon) is a globally distributed, extensively used warm-season turf and forage grass with high tolerance to salinity and drought stress in alkaline environments. However, the origin of the species and genetic mechanisms for salinity tolerance in the species are basically unknown. Accordingly, we set out to study evolution divergence events in the Cynodon genome and to identify genes for salinity tolerance. We developed a 604.0 Mb chromosome-level polyploid genome sequence for bermudagrass 'A12359' (n = 18). The C. dactylon genome comprises 2 complete sets of homoeologous chromosomes, each with approximately 30 000 genes, and most genes are conserved as syntenic pairs. Phylogenetic study showed that the initial Cynodon species diverged from Oropetium thomaeum approximately 19.7-25.4 million years ago (Mya), the A and B subgenomes of C. dactylon diverged approximately 6.3-9.1 Mya, and the bermudagrass polyploidization event occurred 1.5 Mya on the African continent. Moreover, we identified 82 candidate genes associated with seven agronomic traits using a genome-wide association study, and three single-nucleotide polymorphisms were strongly associated with three salt resistance genes: RAP2-2, CNG channels, and F14D7.1. These genes may be associated with enhanced bermudagrass salt tolerance. These bermudagrass genomic resources, when integrated, may provide fundamental insights into evolution of diploid and tetraploid genomes and enhance the efficacy of comparative genomics in studying salt tolerance in Cynodon.

A generalist-specialist trade-off between switchgrass cytotypes impacts climate adaptation and geographic range.

Polyploidy results from whole-genome duplication and is a unique form of heritable variation with pronounced evolutionary implications. Different ploidy levels, or cytotypes, can exist within a single species, and such systems provide an opportunity to assess how ploidy variation alters phenotypic novelty, adaptability, and fitness, which can, in turn, drive the development of unique ecological niches that promote the coexistence of multiple cytotypes. Switchgrass, Panicum virgatum, is a widespread, perennial C4 grass in North America with multiple naturally occurring cytotypes, primarily tetraploids (4×) and octoploids (8×). Using a combination of genomic, quantitative genetic, landscape, and niche modeling approaches, we detect divergent levels of genetic admixture, evidence of niche differentiation, and differential environmental sensitivity between switchgrass cytotypes. Taken together, these findings support a generalist (8×)­specialist (4×) trade-off. Our results indicate that the 8× represent a unique combination of genetic variation that has allowed the expansion of switchgrass' ecological niche and thus putatively represents a valuable breeding resource.

Characterization of a new greenbug resistance gene Gb9 in a synthetic hexaploid wheat.

Greenbug [Schizaphis graminum (Rondani)] is a serious insect pest that not only damages cereal crops, but also transmits several destructive viruses. The emergence of new greenbug biotypes in the field makes it urgent to identify novel greenbug resistance genes in wheat. CWI 76364 (PI 703397), a synthetic hexaploid wheat (SHW) line, exhibits greenbug resistance. Evaluation of an F2:3 population from cross OK 14319 × CWI 76364 indicated that a dominant gene, designated Gb9, conditions greenbug resistance in CWI 76364. Selective genotyping of a subset of F2 plants with contrasting phenotypes by genotyping-by-sequencing identified 25 SNPs closely linked to Gb9 on chromosome arm 7DL. Ten of these SNPs were converted to Kompetitive allele-specific polymerase chain reaction (KASP) markers for genotyping the entire F2 population. Genetic analysis delimited Gb9 to a 0.6-Mb interval flanked by KASP markers located at 599,835,668 bp (Stars-KASP872) and 600,471,081 bp (Stars-KASP881) on 7DL. Gb9 was 0.5 cM distal to Stars-KASP872 and 0.5 cM proximal to Stars-KASP881. Allelism tests indicated that Gb9 is a new greenbug resistance gene which confers resistance to greenbug biotypes C, E, H, I, and TX1. TX1 is one of the most widely virulent biotypes and has overcome most known wheat greenbug resistance genes. The introgression of Gb9 into locally adapted wheat cultivars is of economic importance, and the KASP markers developed in this study can be used to tag Gb9 in cultivar development.

Electrochemical Reductive Cross-Coupling of Alkyl or Alkenyl Halides with gem-Difluoroalkenes.

Herein, we describe an electroreductive cross-electrophile coupling protocol for the construction of valuable monofluoroalkenes from easily accessible alkyl or alkenyl halides with gem-difluoroalkenes. The reaction can be conducted under sustainable and mild conditions delivering valuable and functionalized monofluoroalkenes with excellent Z-selectivity. The protocol's most notable advantage is the in situ release of nickel catalyst from the inexpensive electrodes without the addition of extra hazardous metal catalyst and superstoichiometric reductant.

Characterization of Quantitative Trait Loci for Leaf Rust Resistance in the Uzbekistani Wheat Landrace Teremai Bugdai.

Leaf rust, caused by Puccinia triticina, is a major cause of wheat yield losses globally, and novel leaf rust resistance genes are needed to enhance wheat leaf rust resistance. Teremai Bugdai is a landrace from Uzebekistan that is highly resistant to many races of P. triticina in the United States. To unravel leaf rust resistance loci in Teremai Bugdai, a recombinant inbred line (RIL) population of Teremai Bugdai × TAM 110 was evaluated for response to P. triticina race Pt54-1 (TNBGJ) and genotyped using single nucleotide polymorphism (SNP) markers generated by genotyping-by-sequencing (GBS). Quantitative trait loci (QTL) analysis using 5,130 high-quality GBS-SNPs revealed three QTLs, QLr-Stars-2DS, QLr-Stars-6BL, and QLr.Stars-7BL, for leaf rust resistance in two experiments. QLr-Stars-2DS, which is either a new Lr2 allele or a new resistance locus, was delimited to an ∼19.47-Mb interval between 46.4 and 65.9 Mb on 2DS and explained 31.3 and 33.2% of the phenotypic variance in the two experiments. QLr-Stars-6BL was mapped in an ∼84.0-kb interval between 719.48 and 719.56 Mb on 6BL, accounting for 33 to 36.8% of the phenotypic variance in two experiments. QLr.Stars-7BL was placed in a 350-kb interval between 762.41 and 762.76 Mb on 7BL and explained 4.4 to 5.3% of the phenotypic variance. Nine GBS-SNPs flanking these QTLs were converted to kompetitive allele specific PCR (KASP) markers, and these markers can be used to facilitate their introgression into locally adapted wheat lines.

The genetic basis of the root economics spectrum in a perennial grass.

Construction economics of plant roots exhibit predictable relationships with root growth, death, and nutrient uptake strategies. Plant taxa with inexpensively constructed roots tend to more precisely explore nutrient hotspots than do those with costly constructed roots but at the price of more frequent tissue turnover. This trade-off underlies an acquisitive to conservative continuum in resource investment, described as the "root economics spectrum (RES)." Yet the adaptive role and genetic basis of RES remain largely unclear. Different ecotypes of switchgrass (Panicum virgatum) display root features exemplifying the RES, with costly constructed roots in southern lowland and inexpensively constructed roots in northern upland ecotypes. We used an outbred genetic mapping population derived from lowland and upland switchgrass ecotypes to examine the genetic architecture of the RES. We found that absorptive roots (distal first and second orders) were often "deciduous" in winter. The percentage of overwintering absorptive roots was decreased by northern upland alleles compared with southern lowland alleles, suggesting a locally-adapted conservative strategy in warmer and acquisitive strategy in colder regions. Relative turnover of absorptive roots was genetically negatively correlated with their biomass investment per unit root length, suggesting that the key trade-off in framing RES is genetically facilitated. We also detected strong genetic correlations among root morphology, root productivity, and shoot size. Overall, our results reveal the genetic architecture of multiple traits that likely impacts the evolution of RES and plant aboveground-belowground organization. In practice, we provide genetic evidence that increasing switchgrass yield for bioenergy does not directly conflict with enhancing its root-derived carbon sequestration.

Does mandibular advancement with clear aligners have the same skeletal and dentoalveolar effects as traditional functional appliances?

BACKGROUND: The study aimed to compare the dentoskeletal effects of Vanbeek Activator, Herbst, Twin-Block and Mandibular Advancement with clear aligners in children with skeletal Class II malocclusions. METHODS: A sample with sixty-three patients (37 males, 26 females) was included and divided into untreated control group (C, n = 12), Vanbeek Activator group (V, n = 14), Herbst group (H, n = 11), Twin-Block group (TB, n = 12) and MA group (MA, n = 14). Cephalometric analysis and Johnston Pitchfork analysis were performed to quantify the skeletal and dentoalveolar components in molar relationship and overjet correction. Compare the differences of cephalometric data and Johnston-analysis data. RESULTS: The treatment changes showed significant differences in SNB, FH-NP, NA-PA, Co-Go, Co-Pog, ANB, lower facial height ratio, U1-PP, U6-PP, L1-MP and U1-L1. All the appliances improved overjet relationships significantly (Vanbeek, Herbst, Twin-Block and MA were 2.77 mm, 5.53 mm, 4.73 mm and 3.66 mm respectively) with significant retraction of maxillary incisors. The lower incisor displacement of group V and MA was negative, while that of group H and TB was positive and there were significant differences. Molar relationships were also improved by 3.45 mm, 6.85 mm, 3.48 mm and 0.92 mm for Vanbeek, Herbst, Twin-Block and MA. Mandible displacement showed a trend of group H > TB > V > MA. The displacement of maxillary molars in group H was greater than that in group C, TB and MA, and that of mandibular ones was greater than that in group C, V and MA, significantly. Herbst, Twin-Block and MA have more significant dentoalveolar effect than Vanbeek, while Vanbeek has more skeletal effect than the others especially in restraining maxillary growth. CONCLUSIONS: Four appliances are all effective in mandibular advancement, modification of class II molar relationship and deep overjet, with unavoidable increase in lower facial ratio. Vanbeek Activator has the most skeletal effects. Vanbeek and MA have a good control of mandibular incisors while more compensatory lower incisors proclination in Herbst and Twin-Block. Herbst has greater maxillary molar distalization. MA allows aligning and leveling meanwhile leading the mandible forward.

Novel aerosol detection platform for SARS­CoV­2: Based on specific magnetic nanoparticles adsorption sampling and digital droplet PCR detection.

The SARS­CoV­2 virus is released from an infectious source (such as a sick person) and adsorbed on aerosols, which can form pathogenic microorganism aerosols, which can affect human health through airborne transmission. Efficient sampling and accurate detection of microorganisms in aerosols are the premise and basis for studying their properties and evaluating their hazard. In this study, we built a set of sub-micron aerosol detection platform, and carried out a simulation experiment on the SARS­CoV­2 aerosol in the air by wet-wall cyclone combined with immunomagnetic nanoparticle adsorption sampling and ddPCR. The feasibility of the system in aerosol detection was verified, and the influencing factors in the detection process were experimentally tested. As a result, the sampling efficiency was 29.77%, and extraction efficiency was 98.57%. The minimum detection limit per unit volume of aerosols was 250 copies (102 copies/mL, concentration factor 2.5).

Research progress of severe acute respiratory syndrome coronavirus 2 on aerosol collection and detection.

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in late 2019 has negatively affected people's lives and productivity. Because the mode of transmission of SARS-CoV-2 is of great concern, this review discusses the sources of virus aerosols and possible transmission routes. First, we discuss virus aerosol collection methods, including natural sedimentation, solid impact, liquid impact, centrifugal, cyclone and electrostatic adsorption methods. Then, we review common virus aerosol detection methods, including virus culture, metabolic detection, nucleic acid-based detection and immunology-based detection methods. Finally, possible solutions for the detection of SARS-CoV-2 aerosols are introduced. Point-of-care testing has long been a focus of attention. In the near future, the development of an instrument that integrates sampling and output results will enable the real-time, automatic monitoring of patients.

The genetic basis for panicle trait variation in switchgrass (Panicum virgatum).

KEY MESSAGE: We investigate the genetic basis of panicle architecture in switchgrass in two mapping populations across a latitudinal gradient, and find many stable, repeatable genetic effects and limited genetic interactions with the environment. Grass species exhibit large diversity in panicle architecture influenced by genes, the environment, and their interaction. The genetic study of panicle architecture in perennial grasses is limited. In this study, we evaluate the genetic basis of panicle architecture including panicle length, primary branching number, and secondary branching number in an outcrossed switchgrass QTL population grown across ten field sites in the central USA through multi-environment mixed QTL analysis. We also evaluate genetic effects in a diversity panel of switchgrass grown at three of the ten field sites using genome-wide association (GWAS) and multivariate adaptive shrinkage. Furthermore, we search for candidate genes underlying panicle traits in both of these independent mapping populations. Overall, 18 QTL were detected in the QTL mapping population for the three panicle traits, and 146 unlinked genomic regions in the diversity panel affected one or more panicle trait. Twelve of the QTL exhibited consistent effects (i.e., no QTL by environment interactions or no QTL × E), and most (four of six) of the effects with QTL × E exhibited site-specific effects. Most (59.3%) significant partially linked diversity panel SNPs had significant effects in all panicle traits and all field sites and showed pervasive pleiotropy and limited environment interactions. Panicle QTL co-localized with significant SNPs found using GWAS, providing additional power to distinguish between true and false associations in the diversity panel.

Comparative analysis reveals chromosome number reductions in the evolution of African bermudagrass (Cynodon transvaalensis Burtt-Davy).

African bermudagrass (Cynodon transvaalensis Burtt-Davy) (2n = 2x = 18) belongs to the genus Cynodon, tribe Cynodonteae, subfamily Chloridoideae in the grass family Poaceae. The species is frequently crossed with common bermudagrass (Cynodon dactylon Pers.) in developing high-quality hybrid turf cultivars. Molecular resources for C. transvaalensis are scarce; thus, its genomic evolution is unknown. Recently, a linkage map consisting of 1278 markers provided a powerful tool for African bermudagrass genomic research. The objective of this study was to investigate chromosome number reduction events that resulted in the nine haploid chromosomes in this species. Tag sequences of mapped single nucleotide polymorphism markers in C. transvaalensis were compared against genome sequences of Oropetium thomaeum (L.f.) Trin. (2n = 2x = 20), a genomic model in the Cynodonteae tribe. The comparative genomic analyses revealed broad collinearity between the genomes of these two species. The analyses further revealed that two major interchromosomal rearrangements of the paleochromosome ρ12 (ρ1-ρ12-ρ1 and ρ6-ρ12-ρ6) resulted in nine chromosomes in the genome of C. transvaalensis. The findings provide novel information regarding the formation of the initial diploid species in the Cynodon genus.

Mapping QTLs for spring green-up, plant vigor, and plant biomass in two lowland switchgrass populations.

Switchgrass (Panicum virgatum L.) is an important perennial C4 species due to its large potential for cellulosic bioenergy feedstock production. Identification of quantitative trait loci (QTL) controlling important developmental traits is valuable to understanding the genetic basis and using marker-assisted selection (MAS) in switchgrass breeding. One F1 hybrid population derived from NL94 (♀) × SL93 (♂) and one S1 (first-generation selfed) population from NL94 were used in this study. Both the populations showed significant variations for genotype and genotype by environment interactions for three traits studied: plant vigor, spring green-up, and plant biomass. Plant vigor had strong and positive correlations with plant biomass in both populations. Broad-sense heritability estimates for plant vigor ranged from 0.46 to 0.74 and 0.45 to 0.74 in the hybrid and selfed population, respectively. Spring green-up had similar heritability estimates, 0.42-0.78 in the hybrid population, and 0.47-0.82 in the selfed population. Heritability of plant biomass was 0.54-0.64 in the hybrid population and 0.64-0.74 in the selfed population. Fifteen QTLs for spring green-up, 6 QTLs for plant vigor, and 3 QTLs for biomass yield were detected in the hybrid population, whereas 4 QTLs for spring green-up, 4 QTLs for plant vigor, and 1 QTL for biomass yield were detected in the selfed population. Markers associated with these QTLs can be used in MAS to accelerate switchgrass breeding program. This study provided new information in understanding the genetic control of biomass components and demonstrated substantial heterotic vigor that could be explored for breeding hybrid cultivars in switchgrass. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-022-01296-7.

QTL × environment interactions underlie adaptive divergence in switchgrass across a large latitudinal gradient.

Local adaptation is the process by which natural selection drives adaptive phenotypic divergence across environmental gradients. Theory suggests that local adaptation results from genetic trade-offs at individual genetic loci, where adaptation to one set of environmental conditions results in a cost to fitness in alternative environments. However, the degree to which there are costs associated with local adaptation is poorly understood because most of these experiments rely on two-site reciprocal transplant experiments. Here, we quantify the benefits and costs of locally adaptive loci across 17° of latitude in a four-grandparent outbred mapping population in outcrossing switchgrass (Panicum virgatum L.), an emerging biofuel crop and dominant tallgrass species. We conducted quantitative trait locus (QTL) mapping across 10 sites, ranging from Texas to South Dakota. This analysis revealed that beneficial biomass (fitness) QTL generally incur minimal costs when transplanted to other field sites distributed over a large climatic gradient over the 2 y of our study. Therefore, locally advantageous alleles could potentially be combined across multiple loci through breeding to create high-yielding regionally adapted cultivars.

Treatment patterns and outcomes in older women with early breast cancer: a population-based cohort study in China.

BACKGROUND: Despite the proportion of elderly breast cancer patients has been consistently increasing, the optimal treatment modalities for this population have not been well explored. We summarized the treatment outcomes of these patients in our hospital. METHODS: Older patients with early breast cancer were identified from the Breast Cancer Information Management System at West China Hospital, Sichuan University (2000-2019). We compared tumor characteristics and treatment outcomes between the older group (65-74 years old) and the elderly group (≥75 years old). The Kaplan-Meier and Cox regression analysis were conducted to determine significant prognostic factors. RESULTS: In total, 1094 patients were included. The median follow-up time for this cohort was 59 months. The majority of patients underwent surgery and benefited from surgical treatment. Elderly group patients were less likely to receive adjuvant chemotherapy or postmastectomy radiotherapy (PMRT) compared to the older group. However, adjuvant chemotherapy was associated with improved overall survival (OS) (hazard ratio [HR] 0.521, 95% confidence interval [CI] 0.284-0.955, P = 0.035). Subgroup analysis revealed that patients with grade III disease best benefited from adjuvant chemotherapy. PMRT offered a significant improvement in local disease control, but not in OS. Furthermore, endocrine therapy improved the OS of HR-positive patients (HR 0.440, 95%CI 0.261-0.741, P = 0.002), especially for cases aged 65-74 years. Also, receipt of trastuzumab in HER2-positive patients was associated with better OS (HR 0.168, 95%CI 0.029-0.958, P = 0.045). CONCLUSIONS: Our findings suggest that surgery, adjuvant chemotherapy, endocrine and targeted therapy are associated with improved OS in older breast cancer patients. Moreover, clinicopathological characteristics should be comprehensively considered when making treatment decisions for these patients.

NaCl Promotes the Efficient Formation of Haematococcus pluvialis Nonmotile Cells under Phosphorus Deficiency.

Natural astaxanthin helps reduce the negative effects caused by oxidative stress and other related factors, thereby minimizing oxidative damage. Therefore, it has considerable potential and broad application prospects in human health and animal nutrition. Haematococcus pluvialis is considered to be the most promising cell factory for the production of natural astaxanthin. Previous studies have confirmed that nonmotile cells of H. pluvialis are more tolerant to high intensity of light than motile cells. Cultivating nonmotile cells as the dominant cell type in the red stage can significantly increase the overall astaxanthin productivity. However, we know very little about how to induce nonmotile cell formation. In this work, we first investigated the effect of phosphorus deficiency on the formation of nonmotile cells of H. pluvialis, and then investigated the effect of NaCl on the formation of nonmotile cells under the conditions of phosphorus deficiency. The results showed that, after three days of treatment with 0.1% NaCl under phosphorus deficiency, more than 80% of motile cells had been transformed into nonmotile cells. The work provides the most efficient method for the cultivation of H. pluvialis nonmotile cells so far, and it significantly improves the production of H. pluvialis astaxanthin.

SN50 attenuates alveolar hypercoagulation and fibrinolysis inhibition in acute respiratory distress syndrome mice through inhibiting NF-κB p65 translocation.

BACKGROUND: It has been confirmed that NF-κB p65 signaling pathway is involved in the regulation of alveolar hypercoagulation and fibrinolysis inhibition in acute respiratory distress syndrome (ARDS). Whether SN50, a NF-κB cell permeable inhibitor, could attenuate alveolar hypercoagulation and fibrinolysis inhibition in ARDS remains to be elucidated. PURPOSE: We explored the efficacy and potential mechanism of SN50 on alveolar hypercoagulation and fibrinolysis inhibition in ARDS in mice. MATERIALS AND METHODS: Mouse ARDS was made by 50 µl of lipopolysaccharide (LPS) (4 mg/ml) inhalation. Male BALB/c mice were intraperitoneally injected with different does of SN50 1 h before LPS inhalation. Lung tissues were collected for hematoxylin-eosin (HE) staining, wet/dry ratio. Pulmonary expressions of tissue factor (TF), plasminogen activator inhibitor-1 (PAI-1), collagen III, as well as phosphorylated p65 (p-p65), p65 in nucleus (p'-p65), IκBα and IKKα/ß were measured. Bronchoalveolar lavage fluid (BALF) was gathered to test the concentrations of TF, PAI-1, activated protein C (APC) and thrombinantithrombin complex (TAT). DNA binding activity of NF-κB p65 was also determined. RESULTS: After LPS stimulation, pulmonary edema and exudation and alveolar collapse occured. LPS also stimulated higher expressions of TF and PAI-1 in lung tissues, and higher secretions of TF, PAI-1, TAT and low level of APC in BALF. Pulmonary collagen III expression was obviously enhanced after LPS inhalation. At same time, NF-κB signaling pathway was activated with LPS injury, shown by higher expressions of p-p65, p'-p65, p-IKKα/ß, p-Iκα in pulmonary tissue and higher level p65 DNA binding activity. SN50 dose-dependently inhibited TF, PAI-1 and collagen IIIexpressions, and decreased TF, PAI-1, TAT but increased APC in BALF. SN50 treatment attenuated pulmonary edema, exudation and reduced lung tissue damage as well. SN50 application significantly reduced p'-p65 expression and weakened p65 DNA binding activity, but expressions of p-p65, p-IKKα/ß, p-Iκα in cytoplasm of pulmonary tissue were not affected. CONCLUSIONS: SN 50 attenuates alveolar hypercoagulation and fibrinolysis inhibition in ARDS via inhibition of NF-κB p65 translocation. Our data demonstrates that NF-κB p65 pathway is a viable new therapeutic target for ARDS treatment.

Mouth breathing impairs the development of temporomandibular joint at a very early stage.

OBJECTIVES: The study aimed to explore the effects of mouth breathing and hypoxia on the condyle of temporomandibular joint (TMJ) via two animal models. METHODS: 24 four-week-old rats were randomly separated into three groups, consisting of eight control rats, eight intermittent hypoxia (IH) rats, and eight intermittent nasal obstruction (INO) rats. We use the IH model and the INO model to simulate children suffering from hypoxia and mouth breathing. After 16 days, the condyle of TMJ and surrounding white adipose tissue (WAT) and skeletal muscle tissue were obtained for further staining and qRT-PCR. Finally, RNA-seq was used to verify the results. RESULTS: The intermittent hypoxia cannot significantly change the overall structure in the cause of short-term hypoxia stimulation, but the intermittent nasal obstruction can alter the condyle, WAT, and muscle, while also introducing noticeable structural changes in tissue hypoxia and macrophage infiltration. Sequencing data verified these findings and also suggested that this process might involve the Hif-1α/Vegf axis. CONCLUSIONS: Our findings reveal the very early structural impact of mouth breathing on condyle reconstruction in rat models, and hypoxia does not induce evident alteration on condyle. However, since these results are mainly focused on rats, further studies are needed to understand its effects on humans.

QuickAnalysis: A Software Designed and Developed for a Portable On-Site Pathogen Detection System.

To develop a software program used for controlling the portable on-site pathogen detection system which is based on real-time PCR, this software is developed by C# over the Microsoft Visual Studio 2013 and used on local computers which are equipped with Windows systems. Taking the actual demand as the guidance, it constructs according to the framework design and unifies the barcode technology, the cloud service, and the Bluetooth technology. Based on the above methods, this software can meet the demands of the system such as free experiment design, auto-control of the hardware and efficient data management. During the operation of this program, the serial port and network communication between it and the device and web server remains stable, no matter it is processing the data collection or data analysis and display. It is feasible and practical to apply this software to the portable on-site pathogen detection system in clinical practices and research work.

Drug Resistance and Integron Genes in Escherichia coli Isolated from Urinary Tract Infection.

Escherichia coli (E. coli) is a major cause of urinary tract infections. Treatment of these infections with antibiotics is often not effective due to the acquisition of drug-resistance genes by the bacteria. This process is mediated by integrons which belong to bacterial mobile genetic elements. Therefore, the present study addressed the issue of the relation between antibiotic resistance and integron genes in E. coli isolated from patients affected by urinary tract infection. Multiplex PCR assay employed to detect the E. coli integrase gene demonstrated that out of 49 bacterial strains, 26 were carrying class 1 integron and there was no case of bacteria harboring class 2 or class 3 integrons. Correlation analysis documented that E. coli strains harboring class 1 integron exhibited higher resistance towards tobramycin. The variable region gene cassette contained combinations of four genes responsible for antibiotic resistance: dfr17, aadA2, aadA5, and aac(6')-Ib-cr, of which the latter conferred tobramycin resistance. Together, the collected data underscore the need for identification and analysis of integrons in E. coli-induced urinary infections.

The Liquid Level Detection System Based on Pressure Sensor.

Micro-liquid distribution operation has been a core part of the fully automatic liquid handling platform in clinical testing. Accurate and fast automatic detection of liquid level with disposable tip is the precondition to ensure the stability of the whole operation of liquid handling platform. By further research on the liquid level sensing technology of pressure sensor, in this paper we designed a new type of accurate and stable micro-liquid level detection system and verified its stability, instantaneity and accuracy by setting up a small reagent distribution platform. It was shown that the liquid level detection system designed in this paper has reliable stability, good instantaneity and high accuracy, with the liquid level detecting accuracy up to 100%, the response speed after detecting the liquid level reaching millisecond and the depth in the liquid level less than 0.3 mm. Besides, there is no limit on the physical and chemical properties of the liquids to be tested, which is consistent with the technical indicators of the liquid handling platform.