Comparative Study on Enzymatic Characteristics of Two κ-Carrageenases from Carrageenan-Degrading Bacterium Catenovulum agarivorans DS2.

κ-Carrageenase plays an important role in achieving the high-value utilization of carrageenan. Factors such as the reaction temperature, thermal stability, catalytic efficiency, and product composition are key considerations for its large-scale application. Previous studies have shown that the C-terminal noncatalytic domains (nonCDs) could influence the enzymatic properties, of κ-carrageenases, providing a strategy for exploring κ-carrageenases with different properties, especially catalytic products. Accordingly, two κ-carrageenases (CaKC16A and CaKC16B), from the Catenovulum agarivorans DS2, were selected and further characterized. Bioinformatics analysis suggested that CaKC16A contained a nonCD but CaKC16B did not. CaKC16A exhibited better enzymatic properties than CaKC16B, including thermal stability, substrate affinity, and catalytic efficiency. After truncation of the nonCD of CaKC16A, its thermal stability, substrate affinity, and catalytic efficiency have significantly decreased, indicating the vital role of nonCD in maintaining a good enzymatic property. Moreover, CaKC16A degraded κ-carrageenan to produce a highly single κ-neocarratetrose, while CaKC16B produced a single κ-neocarrabiose. CaKC16A could degrade ß/κ-carrageenan to produce a highly single desulfated κ-neocarrahexaose, while CaKC16B produced κ-neocarrabiose and desulfated κ-neocarratetrose. Furthermore, it was proposed that CaKC16A and CaKC16B participate in the B/KC metabolic pathway and serve different roles, providing new insight into obtaining κ-carrageenases with different properties.

TLR4 TIR domain and nucleolin GAR domain synergistically mediate RSV infection and induce neuronal inflammatory damage in SH-SY5Y cells.

Previous research results of our group showed that Toll-like receptor 4 (TLR4) and nucleolin synergistically mediate respiratory syncytial virus (RSV) infection in human central neuron cells, but the specific mechanism remains unclear. Here we designed and synthesized lentiviruses with TIR (674-815 aa), TLR4 (del 674-815 aa), GAR (645-707 aa), and NCL (del 645-707 aa) domains, and obtained stable overexpression cell lines by drug screening, and subsequently infected RSV at different time points. Laser confocal microscopy and coimmunoprecipitation were used for the observation of co-localization and interaction of TIR/GAR domains. Western blot analysis was used for the detection of p-NF-κB and LC3 protein expression. Real-time PCR was used for the detection of TLR4/NCL mRNA expression. ELISA assay was used to measure IL-6, IL-1ß, and TNF-α concentrations and flow cytometric analysis was used for the study of apoptosis. Our results suggest that overexpression of TIR and GAR domains can exacerbate apoptosis and autophagy, and that TIR and GAR domains can synergistically mediate RSV infection and activate the NF-κB signaling pathway, which regulates the secretion of downstream inflammatory factors, such as IL-6, IL-1ß, and TNF-α, and ultimately leads to neuronal inflammatory injury.

Systematic review on carrageenolytic enzymes: From metabolic pathways to applications in biotechnology.

Carrageenan, the major carbohydrate component of some red algae, is an important renewable bioresource with very large annual outputs. Different types of carrageenolytic enzymes in the carrageenan metabolic pathway are potentially valuable for the production of carrageenan oligosaccharides, biofuel, and other chemicals obtained from carrageenan. However, these enzymes are not well-developed for oligosaccharide or biofuel production. For further application, comprehensive knowledge of carrageenolytic enzymes is essential. Therefore, in this review, we first summarize various carrageenolytic enzymes, including the recently discovered ß-carrageenase, carrageenan-specific sulfatase, exo-α-3,6-anhydro-D-galactosidase (D-ADAGase), and exo-ß-galactosidase (BGase), and describe their enzymatic characteristics. Subsequently, the carrageenan metabolic pathways are systematically presented and applications of carrageenases and carrageenan oligosaccharides are illustrated with examples. Finally, this paper discusses critical aspects that can aid researchers in constructing cascade catalytic systems and engineered microorganisms to efficiently produce carrageenan oligosaccharides or other value-added chemicals through the degradation of carrageenan. Overall, this paper offers a comprehensive overview of carrageenolytic enzymes, providing valuable insights for further exploration and application of these enzymes.

Melatonin suppresses TLR4-mediated RSV infection in the central nervous cells by inhibiting NLRP3 inflammasome formation and autophagy.

Respiratory syncytial virus (RSV) infects neuronal cells in the central nervous system (CNS), resulting in neurological symptoms. In the present study, we intended to explore the mechanism of RSV infection-induced neuroinflammatory injury from the perspective of the immune response and sought to identify effective protective measures against the injury. The findings showed that toll-like receptor 4 (TLR4) was activated after RSV infection in human neuronal SY5Y cells. Furthermore, TLR4 activation induced autophagy and apoptosis in neuronal cells, promoted the formation of the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, and increased the secretion of downstream inflammatory cytokines such as interleukin-1ß (IL-1ß), interleukin-18 (IL-18) and tumour necrosis factor-α (TNF-α). Interestingly, blockade of TLR4 or treatment with exogenous melatonin significantly suppressed TLR4 activation as well as TLR4-mediated apoptosis, autophagy and immune responses. Therefore, we infer that melatonin may act on the TLR4 to ameliorate RSV-induced neuronal injury, which provides a new therapeutic target for RSV infection.

A rapid one-step affinity purification of C-phycocyanin from Spirulina platensis.

The high-purity phycocyanin has a high commercial value. Most current purification methods of C-phycocyanin involve multiple steps, which are complicated and time-consuming. To solve the problem, this research was studied, and an efficient affinity chromatography purification for C-phycocyanin from Spirulina platensis was developed. Through molecular docking simulation, virtual screening of ligands was performed, and ursolic acid was identified as the specific affinity ligand, which coupled to Affi-Gel 102 gel via 1-ethyl (3-dimethylaminopropyl)-3-carbodiimide, hydrochloride as coupling agent. With this customized and synthesized resin, a high-efficiency one-step purification procedure for C-phycocyanin was developed and optimized, the purity was determined to be 4.53, and the yield was 69 %. This one-step purification protocol provides a new approach for purifying other phycobilin proteins.

Ectopic pheochromocytomas in the third trimester: A case report and literature review.

INTRODUCTION: To investigate the clinical features, pregnancy care, timing, and approaches of pregnancy termination as well as the perinatal management of pregnant women with ectopic pheochromocytomas (EPCC) (paragangliomas, PGL). METHODS: We report the diagnosis and treatment of a pregnant women with EPCC which was confirmed in the third trimester in our hospital. Literature in relation to EPCC during pregnancy both in and outside China was searched for data analysis such as maternal clinical features and maternal and fetal prognosis. RESULTS: A total of 20 papers including 21 cases (plus ours) were retrieved. The average age of pregnant patients was 28 years old (from 21 to 37). Two patients presented no hypertension. Nineteen had hypertension in various extent with the accompany of headache (11 cases, 57.9%), palpitations (8 cases, 42.1%), sweating (6 cases, 31.6%), nausea (6 cases), abdominal pain (2 cases), etc. The tumor was found in the chest in 3 patients, in the upper abdomen in 1 patient, in the middle abdomen in 10 patients, between the lower abdomen and pelvic cavity in 3 patients and in the pelvic cavity in 3 patients. Five patients had a surgical removal of the tumor before delivery, 3 during cesarean section and 10 after giving birth. CONCLUSION: EPCC (PGL) during pregnancy is a rare extra-adrenal tumor, whose manifestations are often confused with those of pregnancy-induced hypertension. It is extremely hard to diagnosis the disease before surgery. Patients still have an opportunity of undergoing spontaneous delivery if their tumors have been removed before labor. However, for patients whose pheochromocytomas is localized before labor, it is better to terminate their pregnancy via cesarean section in a proper time according to their obstetric conditions, while under the supervision of multidisciplinary specialists. The preparations of both α and ß adrenergic receptor blocker treatment that is normally carried out before PGL removal surgery are unnecessary to be overemphasized before the cesarean section.

Expanding the application range of the κ­carrageenase OUC-FaKC16A when preparing oligosaccharides from κ-carrageenan and furcellaran.

Carrageenan oligosaccharides are important products that have demonstrated numerous bioactivities useful in the food, medicine, and cosmetics industries. However, the specific structure-function relationships of carrageenan oligosaccharides are not clearly described due to the deficiency of high specific carrageenases. Here, a truncated mutant OUC-FaKC16Q based on the reported κ-neocarratetrose (Nκ4)-producing κ-carrageenase OUC-FaKC16A from Flavobacterium algicola was constructed and further studied. After truncating the C-terminal Por_Secre_tail (PorS) domain (responsible for substrate binding), the catalytic efficiency and temperature stability decreased to a certain extent. Surprisingly, this truncation also enabled OUC-FaKC16Q to hydrolyze Nκ4 into κ-neocarrabiose (Nκ2). The offset of Arg265 residue in OUC-FaKC16Q may explain this change. Moreover, the high catalytic abilities, the main products, and the degradation modes of OUC-FaKC16A and OUC-FaKC16Q toward furcellaran were also demonstrated. Data suggested OUC-FaKC16A and OUC-FaKC16Q could hydrolyze furcellaran to produce mainly the desulfated oligosaccharides DA-G-(DA-G4S)2 and DA-G-DA-G4S, respectively. As a result, the spectrum of products of κ-carrageenase OUC-FaKC16A has been fully expanded in this study, indicating its promising potential for application in the biomanufacturing of carrageenan oligosaccharides with specific structures. Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-023-00181-2.

Are the original SARS-CoV-2 novel mutants from in vitro culture able to escape the immune response?

Monitoring variations in the virus genome to understand the SARS-CoV-2 evolution and spread of the virus is extremely important. Seven early SARS-CoV-2 isolates in China were cultured in vitro and were analyzed for their viral infectivity through viral growth assay, tissue culture infectious dose (TCID50 ) assay, spike protein quantification, and next generation sequencing analysis, and the resultant mutations in spike protein were used to generate the corresponding pseudoviruses for analysis of immune escape from vaccination and postinfection immunity. The results revealed that in vitro cultured SARS-CoV-2 virus had much higher mutation frequency (up to ~20 times) than that in infected patients, suggesting that SARS-CoV-2 diversify under favorable conditions. Monitoring viral mutations is not only helpful for better understanding of virus evolution and virulence change, but also the key to prevent virus transmission and disease progression. Compared with the D614G reference strain, a pseudovirus strain of SARS-CoV-2 was constructed with a high mutation rate site on the spike protein. We found some novel spike mutations during in vitro culture, such as E868Q, conferred further immune escape ability.

Graphic Intelligent Diagnosis of Hypoxic-Ischemic Encephalopathy Using MRI-Based Deep Learning Model.

INTRODUCTION: Heterogeneous MRI manifestations restrict the efficiency and consistency of neuroradiologists in diagnosing hypoxic-ischemic encephalopathy (HIE) due to complex injury patterns. This study aimed to develop and validate an intelligent HIE identification model (termed as DLCRN, deep learning clinical-radiomics nomogram) based on conventional structural MRI and clinical characteristics. METHODS: In this retrospective case-control study, full-term neonates with HIE and healthy controls were collected in two different medical centers from January 2015 to December 2020. Multivariable logistic regression analysis was implemented to establish the DLCRN model based on conventional MRI sequences and clinical characteristics. Discrimination, calibration, and clinical applicability were used to evaluate the model in the training and validation cohorts. Grad-class activation map algorithm was implemented to visualize the DLCRN. RESULTS: 186 HIE patients and 219 healthy controls were assigned to the training, internal validation, and independent validation cohorts. Birthweight was incorporated with deep radiomics signatures to create the final DLCRN model. The DLCRN model achieved better discriminatory power than simple radiomics models, with an area under the curve (AUC) of 0.868, 0.813, and 0.798 in the training, internal validation, and independent validation cohorts, respectively. The DLCRN model was well calibrated and has clinical potential. Visualization of the DLCRN highlighted the lesion areas that conformed to radiological identification. CONCLUSION: Visualized DLCRN may be a useful tool in the objective and quantitative identification of HIE. Scientific application of the optimized DLCRN model may save time for screening early mild HIE, improve the consistency of HIE diagnosis, and guide timely clinical management.

The effect of maternal anxiety during pregnancy on the social emotional development among toddlers / 中国学校卫生

Objective@#To explore the impact of maternal anxiety during pregnancy on social emotional development of toddlers aged 1-3 year old, so as to provide references for scientific early parenting and early intervention for toddlers with social emotional difficulties.@*Methods@#From September 2022 to March 2023, a total of 815 toddlers aged 1-3 who underwent physical examinations and their mothers at Nantong Maternal and Child Health Hospital were enrolled. The Chinese Infant Toddler Social and Emotional Assessment (CITSEA) was used to evaluate the social emotional ability among toddlers. Maternal anxiety evaluated using the Self rating Anxiety Scale (SAS) during prenatal visit was collected.@*Results@#The average scores on the externalizing, internalizing, dysregulation and competence domains of the CITSEA were (49.40±9.48,47.42±9.60,48.67± 10.15 , 50.07± 10.20), respectively. Among boys, the score of externalizing domain (50.89±9.45) was higher than that of girls (48.76± 9.50 ), while the score of competence domain (49.22±10.30) was lower than that of girls (51.17±9.84), and the differences were statistically significant( t =2.10, -3.03, P <0.05). The detection rates of abnormalities in the externalizing, internalizing, dysregulation, and competence domains were 7.36%, 7.12%, 7.61%, and 7.24%, respectively. Among them, boys (8.43%,6.32%, 7.96 %,7.49%) and girls (6.19%, 7.99 %,7.22%,6.96%) showed no statistical differences ( χ 2=1.50, 0.85, 0.16, 0.09, P >0.05). There were significant differences in externalizing domain scores（47.77±9.52，49.56±8.95，52.51±9.77） and competence domain scores（51.70±10.38，49.65±10.05，46.68±10.03） among toddlers of different maternal anxiety（normal, mild, moderate to severe） （ F =7.05,7.10, P <0.01）. There were significant differences in the abnormal detection rate of externalizing domain （4.81%，7.54%，11.17%） and competence domain（4.81%，6.96%，11.73%）（ χ 2=6.60，7.98， P ＜0.05）.@*Conclusion@#Maternal anxiety during pregnancy has a negative impact on the social emotional development among toddlers. In order to improve social emotional development of toddlers, multidimensional social support and education during pregnancy should be carried out.

A Novel Carrageenan Metabolic Pathway in Flavobacterium algicola.

Carbohydrate-active enzymes are important components of the polysaccharide metabolism system in marine bacteria. Carrageenase is indispensable for forming carrageenan catalytic pathways. Here, two GH16_13 carrageenases showed likely hydrolysis activities toward different types of carrageenans (e.g., κ-, hybrid ß/κ, hybrid α/ι, and hybrid λ), which indicates that a novel pathway is present in the marine bacterium Flavobacterium algicola to use κ-carrageenan (KC), ι-carrageenan (IC), and λ-carrageenan (LC). A comparative study described the different features with another reported pathway based on the specific carrageenans (κ, ι, and λ) and expanded the carrageenan metabolic versatility in F. algicola. A further comparative genomic analysis of carrageenan-degrading bacteria indicated different distributions of carrageenan metabolism-related genes in marine bacteria. The crucial core genes encoding the GH127 α-3,6-anhydro-d-galactosidase (ADAG) and 3,6-anhydro-d-galactose (d-AHG)-utilized cluster have been conserved during evolution. This analysis further revealed the horizontal gene transfer (HGT) phenomenon of the carrageenan polysaccharide utilization loci (CarPUL) from Bacteroidetes to other bacterial phyla, as well as the versatility of carrageenan catalytic activities in marine bacteria through different metabolic pathways. IMPORTANCE Based on the premise that the specific carrageenan-based pathway involved in carrageenan use by Flavobacterium algicola has been identified, another pathway was further analyzed, and it involved two GH16_13 carrageenases. Among all the characterized carrageenases, the members of GH16_13 accounted for only a small portion. Here, the functional analysis of two GH16_13 carrageenases suggested their hydrolysis effects on different types of carrageenans (e.g., κ, hybrid ß/κ, hybrid α/ι-, and hybrid λ-), which led to the identification of another pathway. Further exploration enabled us to elucidate the novel pathway that metabolizes KC and IC in F. algicola successfully. The coexistence of these two pathways may provide improved survivability by F. algicola in the marine environment.

Characterization of a GH50 ß-Agarase: A Biotechnological Tool for Preparing Oligosaccharides from Agarose and Porphyran.

Agarase is of vital significance for functional agaro-oligosaccharides production from algal dived agarose. Especially, the exolytic agarases have the advantage of obtaining agaro-oligosaccharides with a specific degree of polymerization. Herein, we cloned and expressed a novel glycoside hydrolase (GH) 50 family ß-agarase OUC-PgJC50 from Photobacterium gaetbulicola. The degradation pattern analysis indicated that OUC-PgJC50 not only showed an exolytic activity with main products of neoagarotetraose from hydrolyzing agarose but also show a hydrolytic activity to transform neoagarotetraose into neoagarobiose. This is the first time that the discovery of a neoagarotetraose-producing exolytic GH50 ß-agarase possesses the activity to transform neoagarotetraose into neoagarobiose, which provided new insight into the recognition of the degradation mode of agarases. Molecular docking and sequence alignment analysis further revealed the His654 residue in OUC-PgJC50 may play a vital role in forming a strong force with l-AHG residue at -4 subsite that helps to produce neoagarotetraose from catalyzing agarose. Moreover, the catalytic ability of OUC-PgJC50 toward another agar polysaccharide porphyran was also described that could hydrolyze porphyran into sulfated oligosaccharides, in which the LA6S-d-Gal was the main products. This study is of vital significance for developing the application range of GH50 ß-agarases.

Enzymatic Verification and Comparative Analysis of Carrageenan Metabolism Pathways in Marine Bacterium Flavobacterium algicola.

Marine bacteria usually contain polysaccharide utilization loci (PUL) for metabolizing red algae polysaccharides. They are of great significance in the carbon cycle of the marine ecosystem, as well as in supporting marine heterotrophic bacterial growth. Here, we described the whole κ-carrageenan (KC), ι-carrageenan (IC), and partial λ-carrageenan (LC) catabolic pathways in a marine Gram-negative bacterium, Flavobacterium algicola, which is involved carrageenan polysaccharide hydrolases, oligosaccharide sulfatases, oligosaccharide glycosidases, and the 3,6-anhydro-d-galactose (d-AHG) utilization-related enzymes harbored in the carrageenan-specific PUL. In the pathways, the KC and IC were hydrolyzed into 4-sugar-unit oligomers by specific glycoside hydrolases. Then, the multifunctional G4S sulfatases would remove their nonreducing ends' G4S sulfate groups, while the ι-neocarratetrose (Nι4) product would further lose the nonreducing end of its DA2S group. Furthermore, the neocarrageenan oligosaccharides (NCOSs) with no G4S and DA2S groups in their nonreducing ends would completely be decomposed into d-Gal and d-AHG. Finally, the released d-AHG would enter the cytoplasmic four-step enzymatic process, and an l-rhamnose-H+ transporter (RhaT) was preliminarily verified for the function for transportation of d-AHG. Moreover, comparative analysis with the reported carrageenan metabolism pathways further implied the diversity of microbial systems for utilizing the red algae carrageenan. IMPORTANCE Carrageenan is the main polysaccharide of red macroalgae and is composed of d-AHG and d-Gal. The carrageenan PUL (CarPUL)-encoded enzymes exist in many marine bacteria for decomposing carrageenan to provide self-growth. Here, the related enzymes in Flavobacterium algicola for metabolizing carrageenan were characterized for describing the catabolic pathways, notably, although the specific polysaccharide hydrolases existed that were like previous studies. A multifunctional G4S sulfatase also existed, which was devoted to the removal of G4S or G2S sulfate groups from three kinds of NCOSs. Additionally, the transformation of three types of carrageenans into two monomers, d-Gal and d-AHG, occurred outside the cell with no periplasmic reactions that existed in previously reported pathways. These results help to clarify the diversity of marine bacteria using macroalgae polysaccharides.

Potential dynamic regional brain biomarkers for early discrimination of autism and language development delay in toddlers.

Background: The early diagnosis of autism in children is particularly important. However, there is no obvious objective indices for the diagnosis of autism spectrum disorder (ASD), especially in toddlers aged 1-3 years with language development delay (LDD). The early differential diagnosis of ASD is challenging. Objective: To examine differences in the dynamic characteristics of regional neural activity in toddlers with ASD and LDD, and whether the differences can be used as an imaging biomarker for the early differential diagnosis of ASD and LDD. Methods: Dynamic regional homogeneity (dReHo) and dynamic amplitude of low-frequency fluctuations (dALFF) in 55 children with ASD and 31 with LDD, aged 1-3 years, were compared. The correlations between ASD symptoms and the values of dReHo/dALFF within regions showing significant between-group differences were analyzed in ASD group. We further assessed the accuracy of dynamic regional neural activity alterations to distinguish ASD from LDD using receiver operating characteristic (ROC) analysis. Results: Compared with the LDD group, the ASD group showed increased dReHo in the left cerebellum_8/Crust2 and right cerebellum_Crust2, and decreased dReHo in the right middle frontal gyrus (MFG) and post-central gyrus. Patients with ASD also exhibited decreased dALFF in the right middle temporal gyrus (MFG) and right precuneus. Moreover, the Childhood Autism Rating Scale score was negatively correlated with the dReHo of the left cerebellum_8/crust2 and right cerebellum_crust2. The dReHo value of the right MFG was negatively correlated with social self-help of the Autism Behavior Checklist score. Conclusion: The pattern of resting-state regional neural activity variability was different between toddlers with ASD and those with LDD. Dynamic regional indices might be novel neuroimaging biomarkers that allow differentiation of ASD from LDD in toddlers.

Correlation between sensory characteristics and behavioral problems in children with autism spectrum disorder / 中国学校卫生

Objective@#To understand sensory characteristics and its correlation with behavioral problems among children with autism spectrum disorder (ASD), so as to provide reference basis for early diagnosis and comprehensive intervention of ASD children.@*Methods@#Using cross sectional survey, 193 ASD children trained by Nantong rehabilitation institutions were recruited from September 2021 to February 2022. All children were investigated with the Short Sensory Profile (SSP) and Parent Symptom Questionnaire (PSQ).@*Results@#Among the 193 ASD children, 106 (54.9%) children had abnormal sensory characteristics, including 45 (23.3%) with possible abnormalities and 61 (31.6%) with obvious abnormalities. The abnormal rate of auditory filtering was the highest in the seven dimensions, reaching 85.0%, followed by low strength/weakness, motor sensitivity, taste/smell sensitivity, low response/seeking sensation, vision/hearing sensitivity and tactile sensitivity. The total incidence of sensory abnormalities was 93.3%. There were significant differences in six dimensions of PSQ scale scores of ASD children with different degrees of sensory abnormalities, including conduct problems, learning problems, psychosomatic disorders, impulsive hyperactivity, anxiety and hyperactivity index ( H =38.89, 38.90, 19.53, 46.34, 34.54, 54.90, P <0.01). With the aggravation of sensory abnormalities in children with ASD, the scores of all dimensions of the PSQ scale increased significantly. The total score of SSP was negatively correlated with the six dimensions of conduct problems, learning problems, psychosomatic disorders, impulsive hyperactivity, anxiety and hyperactivity index in PSQ ( r =-0.53, -0.50, -0.32, -0.55, -0.43, -0.61, P <0.01).@*Conclusion@#ASD children generally have sensory abnormalities, which coincide with severity of behavioral problems. There is a positive correlation between sensory abnormalities and behavioral problems in ASD children. More attention should be paid to the abnormal sensory characteristics of children with ASD in the future diagnosis and treatment process.

Crucial Mutations of Spike Protein on SARS-CoV-2 Evolved to Variant Strains Escaping Neutralization of Convalescent Plasmas and RBD-Specific Monoclonal Antibodies.

Small number of SARS-CoV-2 epidemic lineages did not efficiently exhibit a neutralization profile, while single amino acid mutation in the spike protein has not been confirmed in altering viral antigenicity resulting in immune escape. To identify crucial mutations in spike protein that escape humoral immune response, we evaluated the cross-neutralization of convalescent plasmas and RBD-specific monoclonal antibodies (mAbs) against various spike protein-based pseudoviruses. Three of 24 SARS-CoV-2 pseudoviruses containing different mutations in spike protein, including D614G, A475V, and E484Q, consistently showed an altered sensitivity to neutralization by convalescent plasmas. A475V and E484Q mutants are highly resistant to neutralization by mAb B38 and 2-4, suggesting that some crucial mutations in spike protein might evolve SARS-CoV-2 variants capable of escaping humoral immune response.

Advances in agaro-oligosaccharides preparation and bioactivities for revealing the structure-function relationship.

Agaro-oligosaccharides originating from red algae have attracted increasing attention in both basic theoretical research and applied fields due to their excellent bioactivities, which indicates the wide prospects of agaro-oligosaccharides for application in the food, pharmaceutical and cosmetic industries. Thus, a considerable number of studies regarding functional agaro-oligosaccharides preparation as well as the bioactivities exploration have been carried out. Based on these studies, this review first introduced different methods that have been used in agar extraction from red algae, and further provided research progress on arylsulfatase. Then, different methods used for agaro-oligosaccharides production were summarized. Moreover, the abundant bioactivities of agaro-oligosaccharides were described in detail. Finally, this review has discussed current research problems and further provided critical aspects, which may be helpful for revealing the structure-function relationship of agaro-oligosaccharide.

Spatial modeling of gully head erosion on the Loess Plateau using a certainty factor and random forest model.

Gully head erosion significantly contributes to land degradation, and affects gully dynamics on the Loess Plateau of China. Modeling with a gully head erosion susceptibility map (GHEM) is an essential step toward appropriate mitigation measures. This study evaluates the effectiveness of two varieties of advanced data mining techniques-a bivariate statistical model (certainty factor (CF)) and a machine learning model (random forest (RF)) for the accurate mapping of gully head erosion susceptibility taking the Dongzhi Loess Tableland of China as an example at a regional scale. A database comprising 11 geographic and environmental parameters was extracted with 415 spatially distributed gully heads, of which 70% (291) were selected for model training and 30% (124) were used for validation. An accuracy evaluation using the area under the curve (AUC) value revealed that the CF model was 84.1% accurate, while the AUC value of the RF model map was 88.8% accurate. According to the RF method used to assess the relative significance of predictor variables, the most significant factors influencing the spatial distribution of the GHEM were the slope angle, slope aspect, topographic wetness index, and slope length. The GHEM can ultimately aid in decision making with respect to soil planning and management and sustainable development of the study area, which can be applied to other similar loess regions.

Digital PCR assay for the effective detection of COVID-19 patients with SARS-CoV-2 low viral load.

OBJECTIVE: Viral nucleic acid detection by real-time reverse transcription polymerase chain reaction (qPCR) is the current standard method for diagnosis of SARS-CoV-2 infection. However, due to low viral load in some COVID-19 patients, false negative results from this method have been repeatedly reported. METHOD: In this study, we compared the sensitivity and specificity of digital PCR (dPCR) in simulated samples and clinical samples with qPCR assay through a series of vigorous tests. RESULTS: The results showed that dPCR was more sensitive than qPCR especially for samples with low viral load (≤3 copies). In addition, dPCR had similar specificity as qPCR and could effectively distinguish other human coronaviruses and influenza virus from SARS-CoV-2. More importantly, dPCR was more sensitive than qPCR in detecting the virus in the "negative" samples from recurrent COVID-19 patients. CONCLUSIONS: In summary, dPCR could serve as a powerful complement to the current qPCR method for SARS-CoV-2 detection, especially for the samples with extremely low viral load, such as recurrent COVID-19 patients.

Agarose degradation for utilization: Enzymes, pathways, metabolic engineering methods and products.

Red algae are important renewable bioresources with very large annual outputs. Agarose is the major carbohydrate component of many red algae and has potential to be of value in the production of agaro-oligosaccharides, biofuels and other chemicals. In this review, we summarize the degradation pathway of agarose, which includes an upstream part involving transformation of agarose into its two monomers, D-galactose (D-Gal) and 3,6-anhydro-α-L-galactose (L-AHG), and a downstream part involving monosaccharide degradation pathways. The upstream part involves agarolytic enzymes such as α-agarase, ß-agarase, α-neoagarobiose hydrolase, and agarolytic ß-galactosidase. The downstream part includes the degradation pathways of D-Gal and L-AHG. In addition, the production of functional agaro-oligosaccharides such as neoagarobiose and monosaccharides such as L-AHG with different agarolytic enzymes is reviewed. Third, techniques for the setup, regulation and optimization of agarose degradation to increase utilization efficiency of agarose are summarized. Although heterologous construction of the whole agarose degradation pathway in an engineered strain has not been reported, biotechnologies applied to improve D-Gal utilization efficiency and construct L-AHG catalytic routes are reviewed. Finally, critical aspects that may aid in the construction of engineered microorganisms that can fully utilize agarose to produce agaro-oligosaccharides or as carbon sources for production of biofuels or other value-adding chemicals are discussed.