Surface-Based Multimeric Aptamer Generation and Bio-Functionalization for Electrochemical Biosensing Applications.

Multimeric aptamers have gained more attention than their monomeric counterparts due to providing more binding sites for target analytes, leading to increased affinity. This work attempted to engineer the surface-based generation of multimeric aptamers by employing the room temperature rolling circle amplification (RCA) technique and chemically modified primers for developing a highly sensitive and selective electrochemical aptasensor. The multimeric aptamers, generated through surface RCA, are hybridized to modified spacer primers, facilitating the positioning of the aptamers in the proximity of sensing surfaces. These multimeric aptamers can be used as bio-receptors for capturing specific targets. The surface amplification process was fully characterized, and the optimal amplification time for biosensing purposes was determined, using SARS-CoV-2 spike protein (SP). Interestingly, multimeric aptasensors produced considerably higher response signals and affinity (more than 10-fold), as well as higher sensitivity (almost 4-fold) compared to monomeric aptasensors. Furthermore, the impact of surface structures on the response signals was studied by utilizing both flat working electrodes (WEs) and nano-/microislands (NMIs) WEs. The NMIs multimeric aptasensors showed significantly higher sensitivity in buffer and saliva media with the limit of detection less than 2 fg/ml. Finally, the developed NMIs multimeric aptasensors were clinically challenged with several saliva patient samples.

Application of interdisciplinary collaborative hospice care for terminal geriatric cancer patients: a prospective randomized controlled study.

BACKGROUND: Hospice care (HC) is specialized medical care for terminal patients who are nearing the end of life. Interdisciplinary collaborative hospice care (ICHC) is where experts from different disciplines and patients/caregivers form a treatment team to establish shared patient care goals. However, the ICHC efficacy has not been frequently studied in the terminal geriatric cancer patient (TGCP) population. This study aimed to gain insight into ICHC provided to TGCPs by an ICHC team and identify factors to ameliorate multidimensional HC. METHODS: 166 TGCPs were randomized by a computer-generated random number table using an allocation ratio of 1:1. The patients were divided into the ICHC group and life-sustaining treatment (LST) group. The scores of these questionnaires, such as EORTC, QLQ-C30, Hamilton anxiety scale, the median survival time (MST), symptoms improvement, the median average daily cost of drugs (MADDC), the median total cost of drugs (MTDC) in the last 2 days, and medical care satisfaction were observed in both groups. RESULTS: After treatment, the improvement of emotional function and symptoms in the ICHC group were statistically higher than those in the LST group (P < 0.05). The MADDC and the MTDC in the last 2 days were statistically lower in the ICHC group than those in the LSTs group (P < 0.01). In addition, the overall satisfaction situation and the cooperation ability in the ICHC group were statistically higher than those in the LST group (P < 0.01). CONCLUSION: The ICHC could provide TGCPs with coordinated, comfortable, high-quality, and humanistic care.

Differential Pressures of SERINC5 and IFITM3 on HIV-1 Envelope Glycoprotein over the Course of HIV-1 Infection.

Infection of human immunodeficiency virus type 1 (HIV-1) is subject to restriction by cellular factors. Serine incorporator 5 (SERINC5) and interferon-inducible transmembrane 3 (IFITM3) proteins represent two of these restriction factors, which inhibit HIV-1 entry into target cells. Both proteins impede fusion of the viral membrane with the cellular membrane and the formation of a viral fusion pore, and both are countered by the HIV-1 envelope glycoprotein (Env). Given the immense and lasting pressure which Env endures from host adaptive immune responses, it is important to understand whether and how HIV-1 Env is able to maintain the resistance to SERINC5 and IFITM3 throughout the course of infection. We have thus examined a panel of HIV-1 Env clones that were isolated at different stages of viral infection-transmission, acute, and chronic. While HIV-1 Env clones from the transmission stage are resistant to both SERINC5 and IFITM3, as infection progresses into the acute and chronic stages, the resistance to IFITM3 but not to SERINC5 is gradually lost. We further discovered a significant correlation between the resistance of HIV-1 Env to soluble CD4 inhibition and the resistance to SERINC5 but not to IFITM3. Interestingly, the miniprotein CD4 mimetic M48U1 sensitizes HIV-1 Env to the inhibition by SERINC5 but not IFITM3. Together, these data indicate that SERINC5 and IFITM3 exert differential inhibitory pressures on HIV-1 Env over different stages of HIV-1 infection and that HIV-1 Env uses varied strategies to resist these two restriction factors.IMPORTANCE HIV-1 Env protein is exposed to the inhibition not only by humoral response, but also by host restriction factors, including serine incorporator 5 (SERINC5) and interferon-inducible transmembrane 3 (IFITM3). This study investigates how HIV-1 envelope glycoprotein (Env) manages to overcome the pressures from all these different host inhibition mechanisms over the long course of viral infection. HIV-1 Env preserves the resistance to SERINC5 but becomes sensitive to IFITM3 when infection progresses into the chronic stage. Our study also supports the possibility of using CD4 mimetic compounds to sensitize HIV-1 Env to the inhibition by SERINC5 as a potential therapeutic strategy.

Dynamics of Race Structures of Pyricularia oryzae Populations Across 18 Seasons in Guangdong Province, China.

Rice blast, caused by Pyricularia oryzae, is one of the most damaging fungal diseases affecting rice. Understanding how the pathogen's race structure varies over time supports the efforts of rice breeders to develop improved cultivars. Here, the race structure of P. oryzae in Guangdong province, China, where rice is cropped twice per year, was assessed over 18 seasons from 1999 through 2008. The analysis was based on the reactions of a panel of seven differential Chinese cultivars to inoculation with a set of 1,248 isolates of P. oryzae in the province. The "total race frequency" parameter ranged from 14.7 to 39.7%, and the "race diversity index" ranged from 0.63 to 0.93. Twelve (ZA63, ZA31, ZA29, ZA21, ZA13, ZA9, ZB30, ZB17, ZB8, ZB2, ZC14, and ZC8) and two (ZD8 and ZD3) races were recognized as specific to indica and japonica rice types, respectively. Of the 59 distinct races identified, only two indica type races (ZC13 and ZC15) were identified as population-common, and nine indica type races (ZB1, ZB5, ZB6, ZB7, ZB13, ZB15, ZC5, ZC13, and ZC15) and one japonica type race (ZG1) were deemed to be population-dominant; the "total top two race isolate frequency" parameter ranged from 29.8 to 74.5%. On the host side, dynamics of resistance structures of the differential set were divided into three patterns: Both Tetep and Kanto 51 expressed the highest and most stable resistance, both Sifeng 43 and Lijiangxintuanheigu conveyed much lower and unstable resistance, and Zhenlong 13, Dongnong 363, and Heijiang 18 performed intermediate and seasonally dynamic resistance. Three interesting points distinguishing race structures of P. oryzae populations in southern and northeastern China were also discussed.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Role of MxB in Alpha Interferon-Mediated Inhibition of HIV-1 Infection.

Type I interferon inhibits viruses through inducing the expression of antiviral proteins, including the myxovirus resistance (Mx) proteins. Compared to the human MxA protein, which inhibits a wide range of viruses, the MxB protein has been reported to specifically inhibit primate lentiviruses, including HIV-1, and herpesviruses. Further, the role of endogenous MxB in alpha interferon-mediated inhibition of HIV-1 infection was questioned by a recent study showing that MxB knockout did not increase the level of infection by HIV-1 which carried the G protein of vesicular stomatitis virus (VSV), allowing infection of CD4-negative HT1080 cells. In order to further examine the anti-HIV-1 activity of endogenous MxB, we have used CRISPR/Cas9 to deplete MxB in different cell lines and observed a substantial restoration of HIV-1 infection in the presence of alpha interferon treatment. However, this rescue effect of MxB knockout became much less pronounced when infection was performed with HIV-1 carrying the VSV G protein. Interestingly, a CRISPR/Cas9 knockout screen of alpha interferon-stimulated genes in U87-MG cells revealed that the genes for interferon-induced transmembrane protein 2 (IFITM2) and IFITM3 inhibited VSV G-pseudotyped HIV-1 much more strongly than the rest of the genes tested, including the gene for MxB. Therefore, our results demonstrate the importance of MxB in alpha interferon-mediated inhibition of HIV-1 infection, which, however, can be underestimated if infection is performed with VSV G protein-pseudotyped HIV-1, due to the high sensitivity of VSV G-mediated infection to inhibition by IFITM proteins.IMPORTANCE The results of this study reconcile the controversial reports regarding the anti-HIV-1 function of alpha interferon-induced MxB protein. In addition to the different cell types that may have contributed to the different observations, our data also suggest that VSV G protein-pseudotyped HIV-1 is much less inhibited by alpha interferon-induced MxB than HIV-1 itself is. Our results clearly demonstrate an important contribution of MxB to alpha interferon-mediated inhibition of HIV-1 in CD4+ T cells, which calls for using HIV-1 target cells and wild-type virus to test the relevance of the anti-HIV-1 activity of endogenous MxB and other restriction factors.

HIV-1 Employs Multiple Mechanisms To Resist Cas9/Single Guide RNA Targeting the Viral Primer Binding Site.

The clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated protein 9 (Cas9) gene-editing technology has been used to inactivate viral DNA as a new strategy to eliminate chronic viral infections, including HIV-1. This utility of CRISPR-Cas9 is challenged by the high heterogeneity of HIV-1 sequences, which requires the design of the single guide RNA (sgRNA; utilized by the CRISPR-Cas9 system to recognize the target DNA) to match a specific HIV-1 strain in an HIV patient. One solution to this challenge is to target the viral primer binding site (PBS), which HIV-1 copies from cellular tRNA3Lys in each round of reverse transcription and is thus conserved in almost all HIV-1 strains. In this study, we demonstrate that PBS-targeting sgRNA directs Cas9 to cleave the PBS DNA, which evokes deletions or insertions (indels) and strongly diminishes the production of infectious HIV-1. While HIV-1 escapes from PBS-targeting Cas9/sgRNA, unique resistance mechanisms are observed that are dependent on whether the plus or the minus strand of the PBS DNA is bound by sgRNA. Characterization of these viral escape mechanisms will inform future engineering of Cas9 variants that can more potently and persistently inhibit HIV-1 infection.IMPORTANCE The results of this study demonstrate that the gene-editing complex Cas9/sgRNA can be programmed to target and cleave HIV-1 PBS DNA, and thus, inhibit HIV-1 infection. Given that almost all HIV-1 strains have the same PBS, which is copied from the cellular tRNA3Lys during reverse transcription, PBS-targeting sgRNA can be used to inactivate HIV-1 DNA of different strains. We also discovered that HIV-1 uses different mechanisms to resist Cas9/sgRNAs, depending on whether they target the plus or the minus strand of PBS DNA. These findings allow us to predict that a Cas9 variant that uses the CCA sequence as the protospacer adjacent motif (PAM) should more strongly and persistently suppress HIV-1 replication. Together, these data have identified the PBS as the target DNA of Cas9/sgRNA and have predicted how to improve Cas9/sgRNA to achieve more efficient and sustainable suppression of HIV-1 infection, therefore improving the capacity of Cas9/sgRNA in curing HIV-1 infection.

Dynamics of Race Structures of the Rice Blast Pathogen Population in Heilongjiang Province, China From 2006 Through 2015.

Rice blast caused by the fungus Magnaporthe oryzae is one of the most destructive diseases of rice. Its control through the deployment of host resistance genes would be facilitated by understanding the pathogen's race structure. Here, dynamics of race structures in this decade in Heilongjiang province were characterized by Chinese differential cultivars. Two patterns of dynamics of the race structures emerged: both race diversity and population-specific races increased gradually between 2006 and 2011, but they increased much more sharply between 2011 and 2015, with concomitant falls in both the population-common races and dominant races. Four races (ZD1, ZD3, ZD5, and ZE1) were among the top three dominant races over the whole period, indicating that the core of the race structure remained stable through this decade. On the host side, the composition of resistance in the cultivar differential set could be divided in two: the three indica-type entries of the differential set expressed a higher level of resistance to the population of M. oryzae isolates tested than did the four japonica-type entries. The cultivars Tetep and Zhenlong 13 as well as two additional resistance genes α and ε were confirmed as the most promising donors of blast resistance for the local rice improvement programs.[Formula: see text]Copyright © 2019 The Author(s). This is an open-access article distributed under the CC BY-NC-ND 4.0 International license.

Effect of HIV-1 Env on SERINC5 Antagonism.

SERINC5 is able to restrict HIV-1 infection by drastically impairing the infectivity of viral particles. Studies have shown that the HIV-1 Nef protein counters SERINC5 through downregulating SERINC5 from the cell surface and preventing the virion incorporation of SERINC5. In addition, the Env proteins of some HIV-1 strains can also overcome SERINC5 inhibition. However, it is unclear how HIV-1 Env does so and why HIV-1 has two mechanisms to resist SERINC5 inhibition. The results of this study show that neither Env nor Nef prevents high levels of ectopic SERINC5 from being incorporated into HIV-1 particles, except that Env, but not Nef, is able to resist inhibition by virion-associated SERINC5. Testing of a panel of HIV-1 Env proteins from different subtypes revealed a high frequency of SERINC5-resistant Envs. Interestingly, although the SERINC5-bearing viruses were not inhibited by SERINC5 itself, they became more sensitive to the CCR5 inhibitor maraviroc and some neutralizing antibodies than the SERINC5-free viruses, which suggests a possible influence of SERINC5 on Env function. We conclude that HIV-1 Env is able to overcome SERINC5 without preventing SERINC5 virion incorporation. IMPORTANCE: HIV-1 Nef is known to enhance the infectivity of HIV-1 particles and to contribute to the maintenance of high viral loads in patients. However, the underlying molecular mechanism remained elusive until the recent discovery of the antiviral activity of SERINC5. SERINC5 profoundly inhibits HIV-1 but is antagonized by Nef, which prevents the incorporation of SERINC5 into viral particles. Here, we show that HIV-1 Env, but not Nef, is able to resist high levels of SERINC5 without excluding SERINC5 from incorporation into viral particles. However, the virion-associated SERINC5 renders HIV-1 more sensitive to some broadly neutralizing antibodies. It is possible that, under the pressure of some neutralizing antibodies in vivo, HIV-1 needs Nef to remove SERINC5 from viral particles, even though viral Env is able to resist virion-associated SERINC5.

The V3 Loop of HIV-1 Env Determines Viral Susceptibility to IFITM3 Impairment of Viral Infectivity.

Interferon-inducible transmembrane proteins (IFITMs) inhibit a broad spectrum of viruses, including HIV-1. IFITM proteins deter HIV-1 entry when expressed in target cells and also impair HIV-1 infectivity when expressed in virus producer cells. However, little is known about how viruses resist IFITM inhibition. In this study, we have investigated the susceptibilities of different primary isolates of HIV-1 to the inhibition of viral infectivity by IFITMs. Our results demonstrate that the infectivity of different HIV-1 primary isolates, including transmitted founder viruses, is diminished by IFITM3 to various levels, with strain AD8-1 exhibiting strong resistance. Further mutagenesis studies revealed that HIV-1 Env, and the V3 loop sequence in particular, determines the extent of inhibition of viral infectivity by IFITM3. IFITM3-sensitive Env proteins are also more susceptible to neutralization by soluble CD4 or the 17b antibody than are IFITM3-resistant Env proteins. Together, data from our study suggest that the propensity of HIV-1 Env to sample CD4-bound-like conformations modulates viral sensitivity to IFITM3 inhibition.IMPORTANCE Results of our study have revealed the key features of the HIV-1 envelope protein that are associated with viral resistance to the IFITM3 protein. IFITM proteins are important effectors in interferon-mediated antiviral defense. A variety of viruses are inhibited by IFITMs at the virus entry step. Although it is known that envelope proteins of several different viruses resist IFITM inhibition, the detailed mechanisms are not fully understood. Taking advantage of the fact that envelope proteins of different HIV-1 strains exhibit different degrees of resistance to IFITM3 and that these HIV-1 envelope proteins share the same domain structure and similar sequences, we performed mutagenesis studies and determined the key role of the V3 loop in this viral resistance phenotype. We were also able to associate viral resistance to IFITM3 inhibition with the susceptibility of HIV-1 to inhibition by soluble CD4 and the 17b antibody that recognizes CD4-binding-induced epitopes.

Reconstruction of an SSR-based Magnaporthe oryzae physical map to locate avirulence gene AvrPi12.

BACKGROUND: Pathogen avirulence (Avr) genes can evolve rapidly when challenged by the widespread deployment of host genes for resistance. They can be effectively isolated by positional cloning provided a robust and well-populated genetic map is available. RESULTS: An updated, SSR-based physical map of the rice blast pathogen Magnaporthe oryzae (Mo) has been constructed based on 116 of the 120 SSRs used to assemble the last map, along with 18 newly developed ones. A comparison between the two versions of the map has revealed an altered marker content and order within most of the Mo chromosomes. The avirulence gene AvrPi12 was mapped in a population of 219 progeny derived from a cross between the two Mo isolates CHL42 and CHL357. A bulked segregant analysis indicated that the gene was located on chromosome 6, a conclusion borne out by an analysis of the pattern of segregation shown by individual isolates. Six additional PCR-based markers were developed to improve the map resolution in the key region. AvrPi12 was finally located within the sub-telomeric region of chromosome 6, distal to the SSR locus LSM6-5. CONCLUSIONS: The improved SSR-based linkage map should be useful as a platform for gene mapping and isolation in Mo. It was used to establish the location of AvrPi12, thereby providing a starting point for its positional cloning.

[The Advancement of Attenuated Total Reflection Fourier Transform Infrared Technology in Clinical Application].

The authors systemically reviewed the fast development of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and its clinical application in the past decades. The advantages of this objective technique include real time scanning, easy manipulation and no harm to the subjects examined. Combined with pattern recognition methodology and further confirmation with the clinical and pathological diagnosis, the goal of fast differentiation of malignancy from benign lesions could be achieved. ATR-FTIR spectroscopy technique has shown high differential capacity for benign and malignant tissues such as thyroid, breast and pulmonary diseases. ATR-FTIR spectroscopy has being applied in investigating the differential value (the sensitivity, specificity, and accuracy) of metastatic lymph nodes in thyroid and breast cancer with encouraging results. ATR-FTIR technique would become a promising tool in tissue diagnosis intra-operatively. ATR-FTIR spectroscopy has also been widely applied in detecting bio-fluid to differentiate diseases. The serum ATR-FTIR spectroscopy has the ability of reflecting disease-related information in a fingerprint manner with little amount of blood. Several published articles have covered diseases such as glioma, chest pain, prostate cancer, renal failure, Alzheimer's disease, and ovarian cancer. The results of these researches have proved the efficacious discriminate value of this method. As ATR-FTIR spectroscopy has the potential of fast analysis, accurate diagnosis, and low cost-effective value. It would become one of the most important assisting diagnosis tools in future. Follow-up study should focus on enhancing sample quality and enlarging sample size to have further prospective clinical application.

A genome-wide survey reveals abundant rice blast R genes in resistant cultivars.

Plant resistance genes (R genes) harbor tremendous allelic diversity, constituting a robust immune system effective against microbial pathogens. Nevertheless, few functional R genes have been identified for even the best-studied pathosystems. Does this limited repertoire reflect specificity, with most R genes having been defeated by former pests, or do plants harbor a rich diversity of functional R genes, the composite behavior of which is yet to be characterized? Here, we survey 332 NBS-LRR genes cloned from five resistant Oryza sativa (rice) cultivars for their ability to confer recognition of 12 rice blast isolates when transformed into susceptible cultivars. Our survey reveals that 48.5% of the 132 NBS-LRR loci tested contain functional rice blast R genes, with most R genes deriving from multi-copy clades containing especially diversified loci. Each R gene recognized, on average, 2.42 of the 12 isolates screened. The abundant R genes identified in resistant genomes provide extraordinary redundancy in the ability of host genotypes to recognize particular isolates. If the same is true for other pathogens, many extant NBS-LRR genes retain functionality. Our success at identifying rice blast R genes also validates a highly efficient cloning and screening strategy.

The highly polymorphic cyclophilin A-binding loop in HIV-1 capsid modulates viral resistance to MxB.

BACKGROUND: The human myxovirus-resistance protein B (MxB, also called Mx2) was recently reported to inhibit HIV-1 infection by impeding the nuclear import and integration of viral DNA. However, it is currently unknown whether there exist MxB-resistant HIV-1 strains in the infected individuals. Answer to this question should address whether MxB exerts an inhibitory pressure on HIV-1 in vivo and whether HIV-1 has evolved to evade MxB inhibition. FINDINGS: We have examined ten transmitted founder (T/F) HIV-1 strains for their sensitivity to MxB inhibition by infecting CD4+ T cell lines SupT1 and PM1 that were stably transduced to express MxB. Two T/F stains, CH040.c and RHPA.c, were found resistant and this resistance phenotype was mapped to the amino acid positions 87 and 208 in viral capsid. The H87Q mutation is located in the cyclophilin A (CypA) binding loop and has a prevalence of 21% in HIV-1 sequences registered in HIV database. This finding prompted us to test other frequent amino acid variants in the CypA-binding region and the results revealed MxB-resistant mutations at amino acid positions 86, 87, 88 and 92 in capsid. All these mutations diminished the interaction of HIV-1 capsid with CypA. CONCLUSIONS: Our results demonstrate the existence of MxB-resistant T/F HIV-1 strains. The high prevalence of MxB-resistant mutations in the CypA-binding loop indicates the significant selective pressure of MxB on HIV-1 replication in vivo especially given that this viral resistance mechanism operates at expense of losing CypA.

Stepwise arms race between AvrPik and Pik alleles in the rice blast pathosystem.

A stepwise mutation that occurred in both pathogens and their respective hosts has played a seminal role in the co-evolutionary arms race evolution in diverse pathosystems. The process driven by rice blast AvrPik and Pik alleles was investigated through population genetic and evolutionary approaches. The genetic diversity of the non-signal domain of AvrPik was higher than that in its signal peptide domain. Positive selection for particular AvrPik alleles in the northeastern region of China was stronger than in the south. The perfect relationship between the functional lineages and AvrPik allele-specific pathotypes was established by ruling out the nonfunctional lineages derived from additional copies. Only four alleles conditioning stepwise pathotypes were detected in natural populations, which were likely created by only one evolutionary pathway with three recognizable mutation steps. Two non-stepwise pathotypes were determined by two blocks in a network constructed by all 16 possible alleles, indicating that a natural evolution process can be artificially changed by a combination of specific single-nucleotide polymorphisms. Assuming that AvrPik evolution has been largely driven by host selection, the co-evolutionary stepwise relationships between AvrPik and Pik was established. The experimental validation of stepwise mutation is required for the development of sustainable management strategies against plant disease.

Synthesis of High-Fluorescent Diphenyl-anthracene Derivatives and Application in Detection of Nitroaromatic Explosives and Fingerprint Identification.

The development of high-intensity fluorescent materials is always the focuses and forefront projects because of their important applications in displays, sensing and detection fields. In recent years, the detection of explosives has attracted increasing attention due to security and counterterrorism issues. Herein, two diphenyl-anthracene (DPA) derivatives were designed and synthesized by introducing strong electron withdrawing fluorine atoms and cyano-groups to DPA, which exhibited strong fluorescence both in the solution and solid phase with the absolute quantum yields up to 70.4 % and 45.9 % respectively. The detection behavior of nitroaromatic explosives such as picric acid (PA), 2,4,6-trinitrotoluene (TNT) and 3-Nitropropionic acid (3-NP) also shows good sensitivity with the quenching constant as high as 6.3×104  L mol-1 . Theoretical calculation demonstrates that the fluorescence quenching behavior of the two DPA derivatives is caused by the behavior of photoinduced electron transfer (PET) and the resonance energy transfer (RET) studies explained the higher sensitivity and selectivity of both compounds towards PA than other nitro-containing explosives. Furthermore, the strong solid-state fluorescence of the DPA derivatives also shows excellent advantages in enhancing latent fingerprint recognition.

SARS-CoV-2 Accessory Protein ORF8 Targets the Dimeric IgA Receptor pIgR.

SARS-CoV-2 is a highly pathogenic respiratory virus that successfully initiates and establishes its infection at the respiratory mucosa. However, little is known about how SARS-CoV-2 antagonizes the host's mucosal immunity. Recent findings have shown a marked reduction in the expression of the polymeric Ig receptor (pIgR) in COVID-19 patients. This receptor maintains mucosal homeostasis by transporting the dimeric IgA (dIgA) and pentameric IgM (pIgM) across mucosal epithelial cells to neutralize the invading respiratory pathogens. By studying the interaction between pIgR and SARS-CoV-2 proteins, we discovered that the viral accessory protein Open Reading Frame 8 (ORF8) potently downregulates pIgR expression and that this downregulation activity of ORF8 correlates with its ability to interact with pIgR. Importantly, the ORF8-mediated downregulation of pIgR diminishes the binding of dIgA or pIgM, and the ORF8 proteins of the variants of concern of SARS-CoV-2 preserve the function of downregulating pIgR, indicating the importance of this conserved activity of ORF8 in SARS-CoV-2 pathogenesis. We further observed that the secreted ORF8 binds to cell surface pIgR, but that this interaction does not trigger the cellular internalization of ORF8, which requires the binding of dIgA to pIgR. These findings suggest the role of ORF8 in SARS-CoV-2 mucosal immune evasion.

Ultrasound and enzyme treatments on morphology, structures, and adsorption properties of cassava starch.

Porous starch materials are environmentally friendly and renewable and exhibit high adsorption performances. Ultrasound and compound enzyme (α-amylase and glucoamylase) treatments were applied to prepare modified cassava starch. The granules, crystal morphology, crystal structure, and molecular structure of starch were investigated. The hydrolysis degree, solubility, swelling, and adsorption properties of cassava starch were analyzed. After the cassava starch was modified by ultrasound and enzyme treatments, the granule size of the starch decreased, and the surfaces were eroded to form pits, grooves and cavity structure. The starch spherulites weakened or even disappeared. The functional groups of starch did not change significantly, but the degree of crystal order decreased. The double-helix structure was reduced, and the crystal structure was composed of A + V-type crystals, with a decrease in crystallinity. The gelatinization temperature and thermal degradation temperatures enhanced. The enzymatic hydrolysis degree and solubility of the modified cassava starch increased. The swelling degree decreased, and oil adsorption, water adsorption improved. MB adsorption behavior of modified cassava starch closely followed a pseudo-second-order kinetics model and the Langmuir isotherm equation. These findings could help to understand the relationship between the structure and properties of modified starch, and guide its application in the field of adsorption.

The N-terminal region of IFITM3 modulates its antiviral activity by regulating IFITM3 cellular localization.

Interferon-inducible transmembrane (IFITM) protein family members IFITM1, -2, and -3 restrict the infection of multiple enveloped viruses. Significant enrichment of a minor IFITM3 allele was recently reported for patients who were hospitalized for seasonal and 2009 H1N1 pandemic flu. This IFITM3 allele lacks the region corresponding to the first amino-terminal 21 amino acids and is unable to inhibit influenza A virus. In this study, we found that deleting this 21-amino-acid region relocates IFITM3 from the endosomal compartments to the cell periphery. This finding likely underlies the lost inhibition of influenza A virus that completes its entry exclusively within endosomes at low pH. Yet, wild-type IFITM3 and the mutant with the 21-amino-acid deletion inhibit HIV-1 replication equally well. Given the pH-independent nature of HIV-1 entry, our results suggest that IFITM3 can inhibit viruses that enter cells via different routes and that its N-terminal region is specifically required for controlling pH-dependent viruses.

Visualizing the Distribution of Jujube Metabolites at Different Maturity Stages Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry Imaging.

Chinese jujube (also called Chinese date, Ziziphus jujuba Mill.) is an economically important tree in China and provides a rich source of sugars, vitamins, and bioactive components, all of which are indispensable and essential for the composition and participation in life processes of the human body. However, the location of these metabolites in jujube fruits has not been determined. This study applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate the spatial distribution of sugars, organic acids, and other key components in jujube fruits at different developmental periods. Soluble sugars such as hexoses and sucrose/maltose significantly increase with fruit ripening, while organic acids show an overall trend of initially increasing and then decreasing. Procyanidins and rutin exhibit specific distributions in the fruit periphery and peel. These findings suggest that MALDI-MSI can be used to study the spatial distribution of nutritional components in jujube fruits, providing insights into the changes and spatial distribution of substances during jujube fruit development. This technique offers a scientific basis for jujube breeding, utilization, and production.

Corrigendum: Haplotype analysis of chloroplast genomes for jujube breeding.

[This corrects the article DOI: 10.3389/fpls.2022.841767.].