Recent progress in microbial cell surface display systems and their application on biosensors

Microbial cell surface display technology is a recombinant technology to express target proteins on the cell membrane,which can be used to redesign the cell surface with functional proteins and peptides.Bacterial and yeast surface display systems are the most common cell surface display systems of prokaryotic and eukaryotic proteins,that are widely applied as the core elements in the field of biosensors due to their advantages,including enhanced stability,high yield,good safety,expression of larger and more complex proteins.To further promote the performance of biosensors,the biomineralized microbial surface display technology was proposed.This review summarized the different microbial surface display systems and the biomineralized surface display systems,where the mechanisms of surface display and biomineralization were introduced.Then we described the recent progress of their applications on biosensors for different types of detection targets.Finally,the outlooks and tendencies were discussed and forecasted with the expectation to provide some general functions and enlightenments to this aspect of research.

SAR Change Detection Algorithm Combined with FFDNet Spatial Denoising

Objectives:When detecting changes in synthetic aperture radar(SAR)images,the quality of the difference map has an important impact on the detection results,and the speckle noise in the image interferes with the extraction of change information.In order to improve the detection accuracy of SAR image change detection and improve the quality of the difference map,this paper proposes a method that combines the popular deep neural network with the clustering algorithm.Methods:Firstly,the SAR image with speckle noise was constructed,and the FFDNet architecture was used to retrain the SAR image,and the network parameters with better effect on speckle noise suppression were obtained.Then the log ratio operator is generated by using the reconstructed image output from the network.Finally,K-means and FCM clustering algorithms are used to analyze the difference images,and the binary map of change detection results is generated.Results:The experimental results have high detection accuracy on Bern and Sulzberger’s real data,which proves the effectiveness of the method.

SARS-CoV-2 effects in the genitourinary system and prospects of sex hormone therapy

Object:Corona virus disease 2019(COVID-19)is caused by severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),which leads to acute respiratory infection symptoms.SARS-CoV-2 infection is not always limited to the respiratory tract,and renal infection and dysfunction have been shown to be specific risk factors for death.In addition,COVID-19 has a higher incidence,severity and mortality in men than women.This disparity is due to biological rather than comorbid or behavioral sex differences.Because the male reproductive system is unique,the function of sex hormones in COVID-19 infection may explain the differences between males and females.Understanding these factors will provide appropriate prevention measures and adequate triage strategies and guide the drug discovery process.Methods:An electronic search was completed in PubMed,ARXIV,MEDRXIV and BIORXIV.The most relevant articles were systematically reviewed.In addition,single cell RNA sequencing analysis of tissue samples from human cell landscape was conducted.Results:The influence of SARS-CoV-2 on the urogenital system,the possibility of urinary tract transmission and the functions of sex hormones were discussed in this review.Conclusion:Corona viruses can invade the genitourinary system,causing urological symptoms.Identifying the potential genitourinary organ impairments and protecting them from damage are necessary.Since sex hormones have potential as specific drugs,the gonadal hormones substitution therapy should be considered in both sexes in the COVID-19 pandemic.

Addition of the T5 exonuclease increases the prime editing efficiency in plants

Prime editing(PE)is a versatile genome editing tool without the need for double-stranded DNA breaks or donor DNA templates,but is limited by low editing efficiency.We previously fused the M-MLV reverse transcriptase to the Cas9 nickase,generating the PE2(v1)system,but the editing efficiency of this system is still low.Here we develop different versions of PE2 by adding the 50-to-30 exonuclease at different positions of the nCas9-M-MLV RT fusion protein.PE2(v2),in which the T5 exonuclease fused to the N-terminus of the nCas9-MMLV fusion protein enhances prime editing efficiency of base substitutions,deletions,and insertions at several genomic sites by 1.7-to 2.9-fold in plant cells compared to PE2(v1).The improved editing efficiency of PE2(v2)is further confirmed by generating increased heritable prime edits in stable transgenic plants compared to the previously established PE-P1,PE-P2,and PPE systems.Using PE2(v2),we generate herbicide-resistant rice by simultaneously introducing mutations causing amino acid substitutions at two target sites.The PE efficiency is further improved by combining PE2(v2)and dualpegRNAs.Taken together,the increased genome editing efficiency of PE2(v2)developed in this study may enhance the applications of PE in plants.

Effects of yellow and green light stress on emergence,feeding and mating of Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky(Coleoptera:Scarabaeidae)

Light is one of the key environmental factors for insects to survive.Artificial light sources different from natural environmental light can cause light stress in insects.Yellow and green light stress can interfere with the diurnal rhythm of nocturnal moths and their mating,oviposition,and adult longevity.The scarabaeid beetles Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky are widely distributed,and they are very harmful underground pests.In order to clarify the effects of light stress on their behaviors,individuals of both species were exposed to yellow light(565-585 nm)and green light(525-545 nm),with different light intensity gradients of yellow light in a laboratory setting.The short-term light stress treatment of A.corpulenta and H.parallela was carried out at night.The number of beetles emerging per half an hour was recorded,and mating pairs and feeding activity in 24 h were counted.The results showed that yellow and green light stress significantly changed the rhythm and reduced the rate of beetle emergence in the two beetle species investigated.Also,the peak emergence activity was delayed and the feeding and mating activities were significantly reduced.When treated with different intensities of yellow light,it was found that the rate of emergence of A.corpulenta under 10 lx was close to the control groups.The rate of emergence in H.parallela was significantly lower than the control groups before 0:00,in the 60 lx and 110 lx treatment groups,but after 0:00,the emergence rate of H.parallela was significantly higher in the 60 lx and 110 lx treatment groups than other treatments.However,the emergence rhythms in the three light intensity treatment groups are basically the same as in the control groups.The feeding amount and mating beetles in the three light intensity treatment groups were significantly lower than in the control groups.There were no significant differences in the three treatments.The results show that light stress above 10 lx significantly interferes with the behavioral activities of the two beetle species,investigated.This study provides a new approach for a light control technology for nocturnal beetle pest species.

Establishment of correlation between reaction kinetics and carbon structures in the char gasification process

For a gasification process,the char-CO_(2)gasification is the controlling step worthwhile to be deeply investigated.The article chosen corn stalk(CS),poplar sawdust(PS)and bagasse residue(BR)as the typical waste species derived from agricultural,forestal and industrial sources.The char-CO_(2)gasification behavior,reaction kinetics and carbon structure were studied to reveal the intrinsic factors determining the reaction kinetics.Generally,the carbon conversion and maximum conversion rate were influenced by the feedstocks species and char preparation temperatures,as influenced by ash proportion,potassium content in ash and carbon structure of char.The char-CO_(2)reaction for CS was subject more to the catalytic effect of alkali compositions,while pore structure affected more the gasification reaction for PS char.The isoconversional kinetic analysis indicated that the gasification reaction became stable at carbon conversion of 0.5.Subsequently,sectionalized kinetic parameters were calculated for the initial gasification temperature to the temperature reaching 50%conversion.The result showed that high initial gasification temperature increased the char-CO_(2)gasification barrier to hardly start the reaction but accelerate the reaction rate.The carbon structure analyses further clarified that the reaction activation energy was highly related to the microcrystalline structure of carbon,while the reaction rate was more determined by carbon pore structure.

Friction of metal-matrix self-lubricating composites: Relationships among lubricant content, lubricating film coverage, and friction coefficient

Metal-matrix self-lubricating composites can exhibit excellent tribological properties owing to the release of solid lubricant from the matrix and the formation of a lubricating film on the tribosurface.The coverage of the lubricating film on a worn surface significantly influences the sliding process.However,it is difficult to quantify the film coverage owing to the thin and discontinuous character of the lubricating film and the high roughness of the worn surface.A quantitative characterization of the lubricating film coverage based on X-ray photoelectron spectroscopy(XPS)analysis was developed in this study.The friction tests of Cu-MoS2 composites with a MoS2 content of 0-40 vol%were conducted,and the worn surfaces of the composites were observed and analyzed.Further,the influence of the MoS2 volume content on the coverage of the lubricating film on the worn surface was investigated.The relationships among the volume fraction of the lubricant,coverage of the lubricating film,and the friction coefficient were established.The friction model for the metal matrix self-lubricating composites was developed and verified to facilitate the composition design and friction coefficient prediction of self-lubricating composites.

Photoreceptive reaction spectrum effect and phototactic activity intensity of locusts’ visual display characteristics stimulated by spectral light

To reveal the nature of locusts’visual reaction when stimulated by light,and to clarify the regulation characteristics of locusts’phototactic visual physiology and obtain good spectral light features for locusts’phototactic action,this study investigated locusts’visual spectrum response by characterizing their photoreceptive reaction to LED light using an AvaSpec fiber-optic spectrometer system.Locusts’phototactic response to spectral light was compared using this system.The results showed that locusts’visual reaction characterization presents a photo-induced vision spectrum effect and that by offsetting the main wavelength of light and the spectral peak intensity,a time-varying bio-regulation effect emerges.In addition,locusts’visual regulation ability to UV light is higher than that to violet light,whereas their reaction intensity is lower than to violet light,and the visual bio-regulatory force of locusts’visual system absorbing orange light to react sensitively becomes gradually higher than when absorbing green light as time goes on.Moreover,corresponding to nominal illumination with the same radiant energy and a visual spectrum response stimulated by UV,violet,orange,and green light,it appears that the visual spectrum window is symmetrical around 382 nm,400 nm,602 nm,and 530 nm,respectively,with no significant difference between spectral amplitudes and having a time-varying incremental characteristic with amplitude peak width.This indicates that the stimulus intensity of UV,violet,orange,and green light exceeds locusts’visual tolerance,causing them to generate regulation inactivation as a visual physiological reaction,whereas the visual window response effect stimulated by UV light presents an illumination timeliness effect.Simultaneously,time-varying characteristics of locusts’bio-behavior intensity show that light intensity can make up for locusts’visual sensitivity differences at various spectral wavelengths.Presented with differential response time,photosensitive behavior intensity,and induction effect induced by orange light,time is superior for orange light,the stimulation effect caused by violet light is the strongest,and the phototactic synergy effect caused by UV light is the best.

Controlled preparation and application of glutathione capped gold and platinum alloy nanoclusters with high peroxidase-like activity

In the present study,we have prepared glutathione capped gold and platinum alloy nanoclusters(AuPtNCs)in a controlled way by employing the hydrothermal method and optimized through adjusting the ratio of raw materials,reaction temperature,and time.Compared with the corresponding monometallic gold and platinum nanoclusters,the alloy nanoclusters’catalytic activity is improved dramatically in the oxidation of 3,3,5,5-tetramethylbenzidine(TMB)in the presence of H_(2)O_(2).And the maximum velocity is calculated to be 106×10^(-8)M·s^(-1) for TMB as substrate,being much better than that of other reported metallic nanoclusters and nanoparticles.Further study shows that the high catalytic activity mainly attributes to the synergistic effect of gold and platinum.Besides,they have been applied to determine H_(2)O_(2)in the presence of TMB,which shows high sensitivity with a limit of detection(LOD)at 100 n M.The proposed method has been used to determine H_(2)O_(2)in milk and contact lens solutions,which shows very good recovery and exhibits high practical application potential.Therefore,the present study provides a new type of alloy nanoclusters with high peroxidase-like activity,which will inspire more research interests on doping and alloying with Pt to improve the catalytic activity of metal nanoclusters.

Influences of yellow and green lights on the visual response of western flower thrips and field verification

This study aimed to determine the effects of spectral light characteristics on the visual response of the western flower thrips,the strengthening mechanism of thrips response behavior regulated by light,and thrips response characteristics to contrast light.Light with combined and single wavelength were tested by using a self-made behavior response device for thrips.Light sources for trapping thrips were made to verify the trapping effect on thrips in a greenhouse,and the reasons for changes in thrips behavior were analyzed to characterize the mechanism of their phototactic response.The results showed that the light mode(single,contrast,combined light)affected the thrips visual response and approach response,whereas in contrast light,the effects were optimal.Combination light inhibited the thrips visual response,and when the illumination increased,the thrips visual response to single and combination light intensified,and the thrips approach sensitivity to green light increased in contrast and combination light.However,the light mode did not affect the thrips visual response and sensitivity to spectral light characteristics.The degree of thrips visual response to yellow light was stronger than that to green light,while the degree of thrips visual response to green light was stronger than that to yellow light,indicating that the photo-induced mechanism of the thrips visual response differed from that of the thrips approach response.Moreover,in the greenhouse,the trapping effect of different light sources on thrips was positively correlated with temperature.The trapping effect of green light was optimal,followed by a yellow light source,while the difference of light intensity(illumination,illumination energy)and its photo-thermal intensity between yellow and green light was the reason for the differences in the degree of visual trends and the trapping effects of thrips.However,the sensitivity of thrips responding to different light depended on the difference in the heterogeneous stimulation intensity of different spectral light.Thus,light brightness and photo-thermal effects were the causes of thrips visual responses,while bio-photoelectric reaction effects caused thrips to produce a visual response and affected the degree of the thrips visual response.The results reveal the underlying causes of pest control by light,and provide a theoretical basis for the research and development of pest induction equipment and light arrangements.

Visual response effects of western flower thrips manipulated by different light spectra

To understand how spectral light wavelength affects thrips visual sensitivity,the selective response and the approach sensitivity of western flower thrips were examined.The results showed that light intensity affected thrips selective sensitivity to different spectra,with good visual sensitivity to blue,ultraviolet(UV),and green light changes to UV,violet,and yellow light when illumination increased from 120 lx to 6000 lx.Red light was the sensitive spectral light driving thrips to respond to sensitive light.Under illumination,the best sensitivity response to spectra was violet,while under light energy,this changed to UV when light energy was increased to 120 mW/cm^(2).However,the photo-stimulus properties(illumination or light energy)did not affect the optimal approach sensitivity to UV light.Furthermore,when illumination or light energy stimulated thrips to select two different spectral lights,the total response sensitivity to 12000 lx of UV and violet light were the best(83.27%),while at 60 mW/cm^(2) of UV and yellow light was the best(82.15%).But different photo-stimulus properties influenced on the total approach sensitivity to the stimulation of two different spectral lights when the intensity of light increased,showing that to 12000 lx of violet and green light was the best(53.18%),while for 120 mW/cm^(2) of UV and green light was the best(47.74%).The thrips visual selection response effects stimulated by illumination were different from that induced by light energy,and originated from the thrips different bio-regulatory effects caused by the intensity of light energy of illumination and the intensity of illumination of light energy.Therefore,different photo-stimulus effects can manipulate thrips visual sensitivity to enhance the phototactic effect.

Photo-induced visual response of western flower thrips attracted and repulsed by their phobotaxis spectrum light

This study aimed to clarify the synergistic phototactic attraction-repulsion effect formed by the photo-induced approach-avoidance behavior of thrips,construct phototactic attraction-repulsion light control technologies.The phototactic push-pull effects of red light and UV(365 nm),violet(405 nm),green(520 nm),and yellow(560 nm)single light,as well as their pairwise combined light on the behavior of western flower thrips were investigated using an apparatus that measured thrips response.The study also analyzed the influence of light properties on the phototactic attraction-repulsion effects of thrips and the synergistic effects of red light,and the attraction-repulsion regulation mode.The influence factors on the photo-induced attraction-repulsion effect of thrips were also discussed.The results showed that the red light,presenting the push effect,drove thrips to respond to the sensitive light.The synergistic attraction-repulsion effect of red light and singlelight,as well as that of red light and combined light was related to the light intensity.However,the attraction-repulsion synergism did not reflect thrips response effect and approach effect pulled and pushed by red light and single light,red light and combined light.Thrips preference for green-yellow light,and their behavior depended on the degree of UV light,making the attraction-repulsion synergy of red and green light the strongest.When the light intensity increased,the attraction-repulsion synergy of red and yellow light was the strongest.The attraction-repulsion response to red light and single light was related to the spectral attribute of the single light,with that of red lightand UV light being better.The attraction-repulsion response to red light and combined light was related to light intensity.The intensity of combined light made the attraction-repulsion response to red light and the combined UV and violet light be the best,and the brightness of long-short spectrum light rendered red light and the combined UV and yellow light the best.All such light and combinations were remarkably better than that of red light and UV light.Relative to red light and UV light,the use ofred light and combined light provided limited enhancement to the approach effect of thrips;however,under red light and combined light,violet light intensified the approach of thrips to UV light,with yellow light strengthening the approach to green light.Those results provided a scientific basis for the development of light trapping equipment and the adjustment of light control strategies for thrips.

Bi-functional selection markers assist segregation of transgene-free,genome-edited mutants

Dear Editor,In recent years,CRISPR/Cas9-mediated genome editing has been successfully applied in various plants for functional analysis or crop improvement(Chen et al.,2019).We previously reported DNA-free genome-editing methods to generate transgene-free mutants(Liang et al.,2017;Zhang et al.,2016).