A lipase from Lacticaseibacillus rhamnosus IDCC 3201 with thermostability and pH resistance for use as a detergent additive.

Lipases are important biocatalysts and ubiquitous in plants, animals, and microorganisms. The high growth rates of microorganisms with low production costs have enabled the wide application of microbial lipases in detergent, food, and cosmetic industries. Herein, a novel lipase from Lacticaseibacillus rhamnosus IDCC 3201 (Lac-Rh) was isolated and its activity analyzed under a range of reaction conditions to evaluate its potential industrial application. The isolated Lac-Rh showed a molecular weight of 24 kDa and a maximum activity of 3438.5 ± 1.8 U/mg protein at 60 °C and pH 8. Additionally, Lac-Rh retained activity in alkaline conditions and in 10% v/v concentrations of organic solvents, including glycerol and acetone. Interestingly, after pre-incubation in the presence of multiple commercial detergents, Lac-Rh maintained over 80% of its activity and the stains from cotton were successfully removed under a simulated laundry  setting. Overall, the purified lipase from L. rhamnosus IDCC 3201 has potential for use as a detergent in industrial applications. KEY POINTS: • A novel lipase (Lac-Rh) was isolated from Lacticaseibacillus rhamnosus IDCC 3201 • Purified Lac-Rh exhibited its highest activity at a temperature of 60 °C and a pH of 8, respectively • Lac-Rh remains stable in commercial laundry detergent and enhances washing performance.

Mice harboring the T316N variant in the GABAAR γ2 subunit exhibit sleep-related hypermotor epilepsy phenotypes and hypersynchronization in the thalamocortical pathway.

OBJECTIVE: Sleep-related hypermotor epilepsy (SHE) is a focal epilepsy syndrome characterized by seizures that predominantly occur during sleep. The pathogenesis of these seizures remains unclear. We previously detected rare variants in GABRG2, which encodes the γ2 subunit of γ-aminobutyric acid type A receptor (GABAAR), in patients with SHE and demonstrated that these variants impaired GABAAR function in vitro. However, the mechanisms by which GABRG2 variants contribute to seizure attacks during sleep remain unclear. METHODS: In this study, we designed a knock-in (KI) mouse expressing the mouse Gabrg2 T316N variant, corresponding to human GABRG2 T317N variant, using CRISPR/Cas9. Continuous video-electroencephalogram monitoring and in vivo multichannel electrophysiological recordings were performed to explore seizure susceptibility to pentylenetetrazol (PTZ), alterations in the sleep-wake cycle, spontaneous seizure patterns, and synchronized activity in the motor thalamic nuclei (MoTN) and secondary motor cortex (M2). Circadian variations in the expression of total, membrane-bound, and synaptic GABAAR subunits were also investigated. RESULTS: No obvious changes in gross morphology were detected in Gabrg2T316N/+ mice compared to their wild-type (Gabrg2+/+) littermates. Gabrg2T316N/+ mice share key phenotypes with patients, including sleep fragmentation and spontaneous seizures during sleep. Gabrg2T316N/+ mice showed increased susceptibility to PTZ-induced seizures and higher mortality after seizures. Synchronization of the local field potentials between the MoTN and M2 was abnormally enhanced in Gabrg2T316N/+ mice during light phase, when sleep dominates, accompanied by increased local activities in the MoTN and M2. Interestingly, in Gabrg2+/+ mice, GABAAR γ2 subunits showed a circadian increase on the neuronal membrane and synaptosomes in the transition from dark phase to light phase, which was absent in Gabrg2T316N/+ mice. CONCLUSION: We generated a new SHE mouse model and provided in vivo evidence that rare variants of GABRG2 contribute to seizure attacks during sleep in SHE.

Aminoprocalcitonin protects against hippocampal neuronal death via preserving oxidative phosphorylation in refractory status epilepticus.

Refractory status epilepticus (RSE) is a neurological emergency where sustaining seizure causes severe neuronal death. Currently, there is no available neuroprotectant effective in RSE. Aminoprocalcitonin (NPCT) is a conserved peptide cleaved from procalcitonin, but its distribution and function in the brain remain enigmatic. Survival of neurons relies on sufficient energy supply. Recently, we found that NPCT was extensively distributed in the brain and had potent modulations on neuronal oxidative phosphorylation (OXPHOS), suggesting that NPCT might be involved in neuronal death by regulating energy status. In the present study, combining biochemical and histological methods, high-throughput RNA-sequence, Seahorse XFe analyser, an array of mitochondria function assays, and behavior-electroencephalogram (EEG) monitoring, we investigated the roles and translational values of NPCT in neuronal death after RSE. We found that NPCT was extensively distributed throughout gray matters in rat brain while RSE triggered NPCT overexpression in hippocampal CA3 pyramidal neurons. High-throughput RNA-sequence demonstrated that the influences of NPCT on primary hippocampal neurons were enriched in OXPHOS. Further function assays verified that NPCT facilitated ATP production, enhanced the activities of mitochondrial respiratory chain complexes I, IV, V, and increased neuronal maximal respiration capacity. NPCT exerted multiple neurotrophic effects including facilitating synaptogenesis, neuritogenesis, spinogenesis, and suppression of caspase-3. A polyclonal NPCT immunoneutralization antibody was developed to antagonize NPCT. In the in vitro 0-Mg2+ seizure model, immunoneutralization of NPCT caused more neuronal death, while exogenous NPCT supplementation, though did not reverse death outcomes, preserved mitochondrial membrane potential. In rat RSE model, both peripheral and intracerebroventricular immunoneutralization of NPCT exacerbated hippocampal neuronal death and peripheral immunoneutralization increased mortality. Intracerebroventricular immunoneutralization of NPCT further led to more serious hippocampal ATP depletion, and significant EEG power exhaustion. We conclude that NPCT is a neuropeptide regulating neuronal OXPHOS. During RSE, NPCT was overexpressed to protect hippocampal neuronal survival via facilitating energy supply.

A Lentiviral Pseudotype System to Characterize SARS-CoV-2 Glycoprotein.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2 causes worldwide COVID-19 pandemic and poses a great threat to global public health. Due to its high pathogenicity and infectivity, live SARS-CoV-2 is classified as a BSL-3 agent and has to be handled in BSL-3 condition. Nevertheless, entry of SARS-CoV-2 is mediated by viral spike (S) glycoprotein, and pseudovirus with SARS-CoV-2 S protein can mimic every entry step of SARS-CoV-2 virus and be studied in BSL-2 settings. In this chapter, we describe a detailed protocol of production of lentivirus-based SARS-CoV-2 S pseudovirus and its application in study of virus entry and determination of neutralizing antibody titer of human sera against SARS-CoV-2.

Kurstakin Triggers Multicellular Behaviors in Bacillus cereus AR156 and Enhances Disease Control Efficacy Against Rice Sheath Blight.

Kurstakin is the latest discovered family of lipopeptides secreted by Bacillus spp. In this study, the effects of kurstakin on the direct antagonism, multicellularity, and disease control ability of Bacillus cereus AR156 were explored. An insertion mutation in the nonribosomal peptide synthase responsible for kurstakin synthesis led to a significant reduction of antagonistic ability of AR156 against the plant-pathogenic fungi Rhizoctonia solani, Ascochyta citrullina, Fusarium graminearum, and F. oxysporum f. sp. cubense. The loss of kurstakin synthesis ability significantly impaired the swarming motility of AR156 and reduced biofilm formation and amyloid protein accumulation. Although the loss of kurstakin synthesis ability did not reduce the competitiveness of AR156 under laboratory conditions, the colonization and environmental adaptability of the mutant was significantly weaker than that of wild-type AR156 on rice leaves. The cell surface of wild-type AR156 colonizing the leaf surface was covered by a thick biofilm matrix under a scanning electron microscope, but not the mutant. The colonization ability on rice roots and control efficacy against rice sheath blight disease of the mutant were also impaired. Thus, kurstakin participates in the control of plant diseases by B. cereus AR156 through directly inhibiting the growth of pathogenic fungi and improving long-term environmental adaptability and colonization of AR156 on the host surface by triggering multicellularity. This study explored the multiple functions of kurstakin in plant disease control by B. cereus.

Classification System of National Music Rhythm Spectrogram Based on Biological Neural Network.

National music is a treasure of Chinese traditional culture. It contains the cultural characteristics of various regions and reflects the core value of Chinese traditional culture. Classification technology classifies a large number of unorganized drama documents, which are not labeled, and to some extent, it helps folk music better enter the lives of ordinary people. Simulate folk music of different spectrum and record corresponding music audio under laboratory conditions Through Fourier transform and other methods, music audio is converted into spectrogram, and a total of 2608 two-dimensional spectrogram images are obtained as datasets. The sonogram dataset is imported into the deep convolution neural network GoogLeNet for music type recognition, and the test accuracy is 99.6%. In addition, the parallel GoogLeNet technology based on inverse autoregressive flow is used. The unique improvement is that acoustic features can be quickly converted into corresponding speech time-domain waveforms, reaching the real-time level, improving the efficiency of model training and loading, and outputting speech with higher naturalness. In order to further prove the reliability of the experimental results, the spectrogram datasets are imported into Resnet18 and Shufflenet for training, and the test accuracy of 99.2% is obtained. The results show that this method can effectively classify and recognize music. The experimental results show that this scheme can achieve more accurate classification. The research realizes the recognition of national music through deep learning spectrogram classification for the first time, which is an intelligent and fast new method of classification and recognition.

Influence of cellulose nanocrystal addition on the production and characterization of bacterial nanocellulose.

Bacterial nanocellulose (BNC) is characterized by high purity and excellent mechanical properties; however, its production is constrained by low yield. Therefore, efforts aimed at improving its yield and material properties are imperative. This study investigated the effect of adding different concentrations (0%, 0.5%, and 1.0%) of cellulose nanocrystal (CNC) in Hestrin-Schramm modified medium on the yield and properties of BNC produced by Komagataeibacter sp. SFCB22-18. The BNC yield increased as following an increase in added CNC concentration. Also, the morphology, structure, crystallinity, thermal stability, and mechanical properties of BNC improved after CNC incorporation. A low CNC concentration (0.1%) favored mechanical strength, whereas 0.5% gave the optimum morphology, structural, and thermal stability. These results showed that modifying BNC with CNC could help increase yield and improve its properties, and thus; the potentiality of BNC in various applications would be much enhanced.

Addition of Various Cellulosic Components to Bacterial Nanocellulose: A Comparison of Surface Qualities and Crystalline Properties.

Bacterial nanocellulose (BNC) is a biocompatible material with a lot of potential. To make BNC commercially feasible, improvements in its production and surface qualities must be made. Here, we investigated the in situ fermentation and generation of BNC by addition of different cellulosic substrates such as Avicel and carboxymethylcellulose (CMC) and using Komagataeibacter sp. SFCB22-18. The addition of cellulosic substrates improved BNC production by a maximum of about 5 times and slightly modified its structural properties. The morphological and structural properties of BNC were investigated by using Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy and X-ray diffraction. Furthermore, a type-A cellulose-binding protein derived from Clostridium thermocellum, CtCBD3, was used in a novel biological analytic approach to measure the surface crystallinity of the BNC. Because Avicel and CMC may adhere to microfibrils during BNC synthesis or crystallization, cellulose-binding protein could be a useful tool for identifying the crystalline properties of BNC with high sensitivity.

The Rhinolophus affinis bat ACE2 and multiple animal orthologs are functional receptors for bat coronavirus RaTG13 and SARS-CoV-2.

Bat coronavirus (CoV) RaTG13 shares the highest genome sequence identity with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among all known coronaviruses, and also uses human angiotensin converting enzyme 2 (hACE2) for virus entry. Thus, SARS-CoV-2 is thought to have originated from bat. However, whether SARS-CoV-2 emerged from bats directly or through an intermediate host remains elusive. Here, we found that Rhinolophus affinis bat ACE2 (RaACE2) is an entry receptor for both SARS-CoV-2 and RaTG13, although the binding of RaACE2 to the receptor-binding domain (RBD) of SARS-CoV-2 is markedly weaker than that of hACE2. We further evaluated the receptor activities of ACE2s from additional 16 diverse animal species for RaTG13, SARS-CoV, and SARS-CoV-2 in terms of S protein binding, membrane fusion, and pseudovirus entry. We found that the RaTG13 spike (S) protein is significantly less fusogenic than SARS-CoV and SARS-CoV-2, and seven out of sixteen different ACE2s function as entry receptors for all three viruses, indicating that all three viruses might have broad host rages. Of note, RaTG13 S pseudovirions can use mouse, but not pangolin ACE2, for virus entry, whereas SARS-CoV-2 S pseudovirions can use pangolin, but not mouse, ACE2 enter cells efficiently. Mutagenesis analysis revealed that residues 484 and 498 in RaTG13 and SARS-CoV-2 S proteins play critical roles in recognition of mouse and human ACE2s. Finally, two polymorphous Rhinolophous sinicus bat ACE2s showed different susceptibilities to virus entry by RaTG13 and SARS-CoV-2 S pseudovirions, suggesting possible coevolution. Our results offer better understanding of the mechanism of coronavirus entry, host range, and virus-host coevolution.

Characterization of spike glycoprotein of SARS-CoV-2 on virus entry and its immune cross-reactivity with SARS-CoV.

Since 2002, beta coronaviruses (CoV) have caused three zoonotic outbreaks, SARS-CoV in 2002-2003, MERS-CoV in 2012, and the newly emerged SARS-CoV-2 in late 2019. However, little is currently known about the biology of SARS-CoV-2. Here, using SARS-CoV-2 S protein pseudovirus system, we confirm that human angiotensin converting enzyme 2 (hACE2) is the receptor for SARS-CoV-2, find that SARS-CoV-2 enters 293/hACE2 cells mainly through endocytosis, that PIKfyve, TPC2, and cathepsin L are critical for entry, and that SARS-CoV-2 S protein is less stable than SARS-CoV S. Polyclonal anti-SARS S1 antibodies T62 inhibit entry of SARS-CoV S but not SARS-CoV-2 S pseudovirions. Further studies using recovered SARS and COVID-19 patients' sera show limited cross-neutralization, suggesting that recovery from one infection might not protect against the other. Our results present potential targets for development of drugs and vaccines for SARS-CoV-2.

Glycine 29 Is Critical for Conformational Changes of the Spike Glycoprotein of Mouse Hepatitis Virus A59 Triggered by either Receptor Binding or High pH.

Mouse hepatitis virus (MHV) uses its N-terminal domain (NTD) of the viral spike (S) protein to bind the host receptor mouse carcinoembryonic antigen-related cell adhesion molecule 1a (mCEACAM1a) and mediate virus entry. Our previous crystal structure study of the MHV NTD/mCEACAM1a complex (G. Peng, D. Sun, K. R. Rajashankar, Z. Qian, et al., Proc Natl Acad Sci U S A 108:10696-10701, 2011, https://doi.org/10.1073/pnas.1104306108) reveals that there are 14 residues in the NTD interacting with the receptor. However, their contribution to receptor binding and virus entry has not been fully investigated. Here we analyzed 13 out of 14 contact residues by mutagenesis and identified I22 as being essential for receptor binding and virus entry. Unexpectedly, we found that G29 was critical for the conformational changes of the S protein triggered by either receptor binding or high pH. Replacement of G29 with A, D, F, K, M, and T, to different extents, caused spontaneous dissociation of S1 from the S protein, resulting in an enhancement of high-pH-triggered receptor-independent syncytium (RIS) formation in HEK293T cells, compared to the wild type (WT). In contrast, replacement of G29 with P, a turn-prone residue with a strict conformation, hindered virus entry and conformational changes of the S protein triggered by either receptor binding or pH 8.0, suggesting that the structural turn around G29 and its flexibility are critical. Finally, stabilization of the NTD by G29P had almost no effect on pH-independent RIS induced by the Y320A mutation in the C-terminal domain (CTD) of the S1 subunit, indicating that there might be an absence of cross talk between the NTD and CTD during conformational changes of the S protein. Our study will aid in better understanding the mechanism of how conformational changes of the S protein are triggered.IMPORTANCE Binding of the MHV S protein to the receptor mCEACAM1a triggers conformational changes of S proteins, leading to the formation of a six-helix bundle and viral and cellular membrane fusion. However, the mechanism by which the conformational change of the S protein is initiated after receptor binding has not been determined. In this study, we showed that while replacement of G29, a residue at the edge of the receptor binding interface and the center of the structural turn after the ß1-sheet of the S protein, with D or T triggered spontaneous conformational changes of the S protein and pH-independent RIS, the G29P mutation significantly impeded the conformational changes of S proteins triggered by either receptor binding or pH 8.0. We reason that this structural turn might be critical for conformational changes of the S protein and that altering this structural turn could initiate conformational changes of the S protein, leading to membrane fusion.

Comparative Transcriptome Analysis Reveals the Biocontrol Mechanism of Bacillus velezensis F21 Against Fusarium Wilt on Watermelon.

The watermelon (Citrullus lanatus) is one of the most important horticultural crops for fruit production worldwide. However, the production of watermelon is seriously restricted by one kind of soilborne disease, Fusarium wilt, which is caused by Fusarium oxysporum f. sp. niveum (Fon). In this study, we identified an efficient PGPR strain B. velezensis F21, which could be used in watermelon production for Fon control. The results of biocontrol mechanisms showed that B. velezensis F21 could suppress the growth and spore germination of Fon in vitro. Moreover, B. velezensis F21 could also enhance plant basal immunity to Fon by increasing the expression of plant defense related genes and activities of some defense enzymes, such as CAT, POD, and SOD. To elucidate the detailed mechanisms regulating B. velezensis F21 biocontrol of Fusarium wilt in watermelon, a comparative transcriptome analysis using watermelon plant roots treated with B. velezensis F21 or sterile water alone and in combination with Fon inoculation was conducted. The transcriptome sequencing results revealed almost one thousand ripening-related differentially expressed genes (DEGs) in the process of B. velezensis F21 triggering ISR (induced systemic resistance) to Fon. In addition, the Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment indicated that numerous of transcription factors (TFs) and plant disease resistance genes were activated and validated by using quantitative real-time PCR (qRT-PCR), which showed significant differences in expression levels in the roots of watermelon with different treatments. In addition, genes involved in the MAPK signaling pathway and phytohormone signaling pathway were analyzed, and the results indicated that B. velezensis F21 could enhance plant disease resistance to Fon through the above related genes and phytohormone signal factors. Taken together, this study substantially expands transcriptome data resources and suggests a molecular framework for B. velezensis F21 inducing systemic resistance to Fon in watermelon. In addition, it also provides an effective strategy for the control of Fusarium wilt in watermelon.

[Eye-acupuncture intervention reduces cerebro-cortical apoptosis of neurovascular unit in cerebral ischemia-reperfusion injury rats].

OBJECTIVE: To observe the effect of eye-acupuncture intervention on cerebro-cortical apoptosis of microvascular endothelial cells, neurons and astrocytes (main components of neurovascular unit) and the expression of Bad (an apoptosis promoter) and B-cell lymphoma-extra large(Bcl-xL) proteins in focal cerebral ischemia-reperfusion injury (CIRI) rats, so as to explore its mechanisms underlying improvement of CIRI. METHODS: SD rats were randomly divided into control, sham-operation, model 3 h, model 24 h, model 72 h, eye-acupuncture 3 h, eye-acupuncture 24 h and eye-acupuncture 72 h groups(n＝12 in each group). The CIRI model was established by middle cerebral artery occlusion/reperfusion (MCAO/R). Eye-acupuncture was applied to bilateral "Gan" (Liver) regions, "Shen" (Kidney) regions, "Shangjiao" (Upper-energizer) and "Xiajiao" (Lower-energizer) for 20 min, once 3 h and every 12 h after modeling. The expression levels of Bad and Bcl-xL in the ischemic cerebral cortex tissue were detected by Western blot. The apoptotic neurons, microvascular endothelial cells and astrocytes were assayed by immunofluorescence double labeling (Nestin/TUNEL, CD34/TUNEL and glial fibrillary acidic protein [GFAP]/TUNEL) separately. RESULTS: After modeling, the numbers of apoptotic neurons, microvascular endothelial cells and astrocytes in the ischemic cerebral cortex tissue were significantly increased in the model 72 h group than in the sham-operation group (P<0.01). Following the treatment, the numbers of the 3 types of apoptotic cells were markedly lower in the eye-acupuncture 72 h group than in the model 72 h group(P<0.01). The expression levels of Bad and Bcl-xL proteins were notably up-regulated in the model 3 h, model 24 h and model 72 h groups than in the sham operation group(P<0.01). Following eye-acupuncture intervention, modeling induced increase of the Bad expression were obviously reversed in eye-acupuncture 24 h and eye-acupuncture 72 h groups than those in the 2 model groups(P<0.05). And the increase of Bcl-xL expression levels were further increased in the eye-acupuncture groups in comparison with those in the 3 model groups (P<0.01). CONCLUSION: Eye-acupuncture can down-regulate the expression of Bad protein, and up-regulate the expression of Bcl-xL protein in the ischemic cerebral cortex in CIRI rats, which may contribute to its function in reducing apoptotic neurons, microvascular endothelial cells and astrocytes, suggesting a protective effect of eye-acupuncture intervention on neurovascular unit.

Constituent and effects of polysaccharides isolated from Sophora moorcroftiana seeds on lifespan, reproduction, stress resistance, and antimicrobial capacity in Caenorhabditis elegans.

Sophora moorcroftiana (S. moorcroftiana) is an endemic leguminous dwarf shrub in Tibet, China. Decoctions of the seeds have been used in Chinese folk medicine for dephlogistication, detoxication, and infectious diseases. The present study aimed to investigate the constituent and biological effects of polysaccharides from S. moorcroftiana seeds in Caenorhabditis elegans (C. elegans). Polysaccharides from S. moorcroftiana seeds (SMpol) were extracted with 60% ethanol and constituent was analyzed by GC-MS. SMpol was composed of glucose, galactose and inositol in the molar ratio of 35.7 : 1.3 : 17.0. Synchronized worms were treated with SMpol and then lifespan, motility, reproduction, stress resistance and antimicrobial activity were examined. Compared with the control group, the lifespan was increased to the average of 27.3 days and the number of laying eggs showed a 1.3-fold increase in nematodes treated with SMpol (4 mg·mL-1). In SMpol (4 mg·mL-1) treated worms, there was a 1.1-fold increase in 24-h survival of acute heat stress and a 1.6-fold increase in 2-h survival of oxidative stress The colonization of the bacteria in the SMpol treated nematode was significantly lower than that of the untreated group by 68.3%. In vivo studies showed SMpol significantly extended the life span, improved reproduction, increased stress resistance and antimicrobial capacity of C. elegans. In conclusion, those results indicated that the polysaccharides from S. moorcroftiana seeds were involved in a variety of biological activities leading to its modulatory effects on C. elegans which may be developed as a natural supplement agent.

Identification of H209 as Essential for pH 8-Triggered Receptor-Independent Syncytium Formation by S Protein of Mouse Hepatitis Virus A59.

The spike glycoprotein (S) of murine coronavirus mouse hepatitis virus (MHV) strain A59 uses murine carcinoembryonic antigen-related cell adhesion molecule 1a as its receptor for cell entry, but S protein can also be triggered in the absence of receptor by pH 8.0 alone at 37°C. The mechanism by which conformational changes of this S glycoprotein can be triggered by pH 8.0 has not yet been determined. Here, we show that MHV-A59 S protein is triggered by pH 8.0 at 37°C to induce receptor-independent syncytium (RIS) formation on 293T cells, and that the conformational changes in S proteins triggered by pH 8.0 are very similar to those triggered by receptor binding. We systemically mutated each of 15 histidine residues in S protein and found that H209 is essential for pH 8.0-triggered RIS formation, while H179, H441, H643, and H759 also play important roles in this process. Replacement of H209 with Ala had no effect on receptor binding, but in murine 17Cl.1 cells mutant H209A MHV-A59 showed delayed growth kinetics and was readily outcompeted by wild-type virus when mixed together, indicating that the H209A mutation caused a defect in virus fitness. Finally, the H209A mutation significantly increased the thermostability of S protein in its prefusion conformation, which may raise the energy barrier for conformational change of S protein required for membrane fusion and lead to a decrease in virus fitness in cell culture. Thus, MHV-A59 may have evolved to lower the stability of its S protein in order to increase virus fitness.IMPORTANCE Enveloped viruses enter cells through fusion of viral and cellular membranes, and the process is mediated by interactions between viral envelope proteins and their host receptors. In the prefusion conformation, viral envelope proteins are metastable, and activation to the fusion conformation is tightly regulated, since premature activation would lead to loss of viral infectivity. The stability of viral envelope proteins greatly influences their activation and virus fitness. Here, we report that, similar to the A82V mutation in Ebola glycoprotein, in the S glycoprotein of murine coronavirus MHV-A59, the histidine residue at position of 209 significantly affects the thermal stability of the S protein, determines whether S protein can be activated at 37°C by either pH 8.0 alone or by receptor binding, and affects viral fitness in cell culture. Thus, the spike glycoprotein of MHV-A59 has evolved to retain histidine at position 209 to optimize virus fitness.

[Preparation of sustained-release capsules of zaltoprofen].

OBJECTIVE: To prepare sustained-release capsule of Zaltoprofen (ZP). METHODS: The pellets containing ZP were prepared in the fluid-bed by suspension layering and then coated with ethylcellulose (EC) and hydroxy-propyl methyl cellulose (HPMC). The quality and micromeritics of the ZP pellets were evaluated. The release profile of the AP pellets and the effects of thermal treatment and artificial gastric juice on the release profile were tested. RESULTS: The surface of the coated pellets was smooth, glossy and round. No obvious effect of thermal treatment on the release profile was observed, indicating that thermal treatment on the ZP sustained release capsule is not necessary. The effect of artificial gastric juice on the release profile was significant, indicating that the ZP sustained release capsule should be put into enteric capsule. The release rate of ZP showed lot-in-lot and lot-to-lot uniformity. The dissolution profiles of ZP from the pellets fit into a first grade equation. CONCLUSION: The pellets exhibit ideal sustained-release characteristics in vitro.

Globotriose-functionalized gold nanoparticles as multivalent probes for Shiga-like toxin.

Compared to monovalent carbohydrates, multivalent carbohydrate ligands exhibit significantly enhanced binding affinities to their interacting proteins. Here, we report globotriose (P(k) ligand)-functionalized gold nanoparticle (AuNP) probes for the investigation of multivalent interactions with the B(5) subunit of Shiga-like toxin I (B-Slt). Six P(k)-ligand-encapsulated AuNPs (P(k)-AuNPs) of varying particle size and linker length were synthesized and evaluated for their potential as multivalent affinity probes by using a surface plasmon resonance competition assay. The affinity of these probes for the interacting proteins was greatly affected by nanoparticle size, linker length, and ligand density on nanoparticle surface. For example, the 20-nm 20-P(k)-l-AuNP, which had a relatively long linker showed a >10(8)-fold increase in affinity compared with the mono P(k) ligand. This intrinsic high-affinity AuNP probe specifically captured the recombinant B-Slt from Escherichia coli lysate, and the resulting purity of the B-Slt was >95 %. We also developed a robust P(k)-AuNP-based detection method for Slt-I by combining the technique with silver enhancement.

Surface modification of magnetic nanoparticle via Cu(I)-catalyzed alkyne-azide [2 + 3] cycloaddition.

The Cu(I)-catalyzed alkyne-azide [2 + 3] cycloaddition has been demonstrated to be an effective and orthogonal conjugation reaction to covalently immobilize biomolecules on magnetic nanoparticles (MNPs). The azido group on the MNP surface provides better conjugation efficiency with alkynated molecules. Moreover, the C-terminal alkynated protein was site-specifically immobilized on MNP. The protein binding activity presented by site-specific immobilization is higher than that by random amide bond formation.

A synthetic analog of alpha-galactosylceramide induces macrophage activation via the TLR4-signaling pathways.

Alpha-galactosylceramide (alpha-GalCer), a bioactive glycolipid isolated from the marine sponge Agelas mauritianus, is a potent immunomodulator with therapeutic potential for the treatment of autoimmune diseases and cancer. The Toll-like receptor 4 (TLR4), one of the promising molecular targets for immune-modulating drugs, is commonly expressed in innate immune cells especially macrophages and dendritic cells. Currently, whether alpha-GalCer can activate TLR4 signaling pathways remains unreported. In this study, we examined the effects of alpha-GalCer and its various structural analogs, CCL-1 approximately 47, on TLR4 activation. We found that one alpha-GalCer analog (CCL-34), but not alpha-GalCer itself, strongly stimulated NF-kappaB activity in RAW 264.7 cells. CCL-34 activated NF-kappaB in a TLR4-dependent manner and stimulated TNF-alpha production in bone marrow cells of TLR4-functional C3H/HeN mice but not in those of TLR4-defective C3H/HeJ mice. Furthermore, CCL-34 treatment stimulated NF-kappaB activation and IL-8 production in a 293 cell line constitutively expressing human TLR4, MD-2 and CD14. Treatment of RAW 264.7 cells with CCL-34 also activated TLR4-downstream mitogen-activated protein kinases (ERK, JNK and p38), induced expression of TLR4-downstream genes (TNF-alpha, IL-6, IL-1beta and iNOS) and promoted production of cytokines characteristic of activated macrophages. CCL-34-treated RAW 264.7 cells acquired a distinct morphology similar to that of LPS-activated macrophages and exhibited higher phagocytotic activity. Moreover, treatment with a TLR4-neutalizing antibody inhibited the CCL-34-induced morphological alteration. In summary, we identify a novel synthetic compound CCL-34 that can activate macrophages via TLR4-dependent signaling pathways. Our results suggest that CCL-34 is an immune modulator and may serve as a potential drug lead for immunotherapy.