Cells not only contain membrane-bound organelles (MBOs), but also membraneless organelles (MLOs) formed by condensation of many biomacromolecules. Examples include RNA-protein granules such as nucleoli and PML nuclear bodies (PML-NBs) in the nucleus, as well as stress granules and P-bodies in the cytoplasm. Phase separation is the basic organizing principle of the form of the condensates or membraneless organelles (MLOs) of biomacromolecules including proteins and nucleic acids. In particular, liquid-liquid phase separation (LLPS) compartmentalises and concentrates biological macromolecules into liquid condensates. It has been found that phase separation of biomacromolecules requires some typical intrinsic characteristics, such as intrinsically disordered regions, modular domains and multivalent interactions. The phase separation of biomacromolecules plays a key role in many important cell activities. In recent years, the phase separation of biomacromolecules phase has become a focus of research in gene transcriptional regulation. Transcriptional regulatory elements such as RNA polymerases, transcription factors (TFs), and super enhancers (SEs) all play important roles through phase separation. Our group has previously reported for the first time that long-term inactivation or absence of assembly factors leads to the formation of condensates of RNA polymerase II (RNAPII) subunits in the cytoplasm, and this process is reversible, suggesting a novel regulatory model of eukaryotic transcription machinery. The phase separation of biomacromolecules provides a biophysical understanding for the rapid transmission of transcriptional signals by a large number of TFs. Moreover, phase separation during transcriptional regulation is closely related to the occurrence of cancer. For example, the activation of oncogenes is usually associated with the formation of phase separation condensates at the SEs. In this review, the intrinsic characteristics of the formation of biomacromolecules phase separation and the important role of phase separation in transcriptional regulation are reviewed, which will provide reference for understanding basic cell activities and gene regulation in cancer.

The ICR(Institute of Cancer Research)mouse infection model was constructed to study the pathogenicity of Sal-monella Telelkebir serotype,and the pathogenic identification of mouse isolates was carried out.Observe the bacterial excretion cycle,evaluate the pathogenicity of Salmonella serotype to mice,and calculate the LD50 by the changes in clinical characteris-tics,histopathology and tissue bacterial load of infected mice;by flight mass spectrometry,biochemical identification,serotype identification,molecular typing and other experiments,compared with human isolates;virulence gene analysis was carried out by PCR experiment and whole genome sequencing.The LD50 of Salmonella Telelkebir is 2.67 × 108 CFU/mL;curling and fluffing may occur 0.5 h after infection;autopsy of dead mice showed that the small intestine was severely congested,with more bubbles and fluid accumulation,cecal necrosis,liver apical degeneration and necrosis,necrotic foci on the surface of the kidney and spleen atrophy;the bacterial load of spleen,kidney,lung,liver and jejunum in mice reached its peak at 3 days after infection,while that of heart at 6 days;the bacterial excretion time of the high-dose group exceeded 100 days;The level of CD3 in tissues increased with increasing dose,with inflammatory cell infiltration,myocardial capillary dilation and hyperemia,large area of vacuoles,degeneration and necrosis of hepatocytes,obvious enlargement of splenic sinus,blurred zoning,thickening of glomerular basement membrane,partial exfoliation of ciliated epithelium,atrophy and exfoliation of jejunal villi;PCR and whole genome sequencing revealed Salmonella-related virulence genes such as cdtB,plt A and pltB.This study was the first to successfully establish the ICR mouse model of Salmonella Telelkebir,demonstrating that this serotype of Salmonella has some pathogenicity.

Objective To study the in vitro expression of three phenylalanine hydroxylase(PAH)mutants(p.R243Q,p.R241C,and p.Y356X)and determine their pathogenicity.Methods Bioinformatics techniques were used to predict the impact of PAH mutants on the structure and function of PAH protein.Corresponding mutant plasmids of PAH were constructed and expressed in HEK293T cells.Quantitative reverse transcription polymerase chain reaction was used to measure the mRNA expression levels of the three PAH mutants,and their protein levels were assessed using Western blot and enzyme-linked immunosorbent assay.Results Bioinformatics analysis predicted that all three mutants were pathogenic.The mRNA expression levels of the p.R243Q and p.R241C mutants in HEK293T cells were similar to the mRNA expression level of the wild-type control(P>0.05),while the mRNA expression level of the p.Y356X mutant significantly decreased(P<0.05).The PAH protein expression levels of all three mutants were significantly reduced compared to the wild-type control(P<0.05).The extracellular concentration of PAH protein was reduced in the p.R241C and p.Y356X mutants compared to the wild-type control(P<0.05),while there was no significant difference between the p.R243Q mutant and the wild type control(P>0.05).Conclusions p.R243Q,p.R241C and p.Y356X mutants lead to reduced expression levels of PAH protein in eukaryotic cells,with p.R241C and p.Y356X mutants also affecting the function of PAH protein.These three PAH mutants are to be pathogenic.[Chinese Journal of Contemporary Pediatrics,2024,26(2):188-193]

Post-stroke cognitive impairment(PSCI)is a prevalent functional impairments following stroke that seriously affects patients'quality of life and daily activities.Studies indicate a close relationship between intestinal microflora dysbiosis and central nervous system diseases.Intestinal microflora profoundly impacts on human physiological health,contributing to the stability of nervous,metabolic and immune systems through regulation of the gut-brain axis.An increasing number of studies confirmed the important role of the gut microbiome-gut-brain axis in the occurrence and development of stroke and its associated PSCI,and regulation of microbiome-gut-brain could be potential target to treatment of PSCI.This review summarizes research progress on gut microbiome-gut-brain axis and PSCI to provide a reference for exploration of related mechanisms and clinical prevention and treatment strategies.

Objective To explore the current status of H.pylori infection in the natural population of Sanya City,analyze its influencing factors,and provide a reference basis for the prevention and control of H.pylori infection.Methods A total of 677 residents from four districts of Sanya City were selected by overall stratified random sampling method,and were subjected to urea 14C breath test and questionnaire survey to calculate the positive rate of H.pylori in the natural population and analyze the influencing factors of H.pylori infection.Results A total of 606 residents were included,and the number of H.pylori positive detections was 261,with a positive detection rate of 38.5％.Among them,different ethnicity,marital status,smoking,eating vegetables and fruits,and literacy level were associated with H.pylori infection(P＜0.05);gender,age,BMI,alcohol consumption,drinking water source,betel quid chewing,and the number of cohabitants were not significantly associated with H.pylori infection(P＞0.05).Family infection was an independent risk factor for H.pylori infection in the natural population of Sanya City,and Li ethnicity,frequent consumption of fruits and vegetables,and college and higher education level were independent protective factors for H.pylori infection in the natural population of Sanya City.Conclusion The rate of H.pylori infection in the natural population of Sanya City is lower than the national average.Consuming more fruits and vegetables and improving the awareness of hygiene protection are conducive to the prevention of H.pylori infection;and the promotion of the family and related members with the same examination and treatment is important to avoid aggregation of infection within the family.

The epidemiology and etiology of three suspected cases of imported skin diphtheria infection in Fujian Province were investigated.Secretion samples of patients with skin damage were collected for isolation and culture of Corynebacterium diphtheriae.Biochemical identification and mass spectrum analysis of pure cultures of suspected C.diphtheriae were conduc-ted,the virulence-related genes,including diphtheria toxin reporter(dtxR),toxin A(toxA),and toxin B(toxB)were detec-ted,and multilocus sequence typing(MLST)was performed.All three cases had typical clinical manifestations of cutaneous diphtheria,and C.diphtheriae was isolated from the damaged skin.The virulence genes of two C.diphtheriae strains isolated from two cases were identified as dtxR(+),toxA(-),and toxB(-),and the MLST type was ST-703.The virulence genes of C.diphtheriae isolated from one case were identified as dtxR(+),toxA(+),toxB(+),and the MLST type was ST-248.There is an increased risk of diphtheria in Fujian Province.C.diphtheriae without diphtheria toxin genes can also cause skin diphtheria.

This study was aimed at understanding the genomic characteristics of the Vibrio cholerae O1 group isolated from humans in Fujian Province,to provide essential data for the molecular epidemiological study of cholera.From 2008 to 2022,16 strains of the V.cholerae O1 group from patients and carriers were collected,and antibiotic sensitivity was determined accord-ing to the minimum inhibitory concentration(MIC).The whole genome sequences obtained through second generation sequen-cing were analyzed in open source software,including snippy,Roary,and Prokka,as well as online analysis websites,inclu-ding NCBI and BacWGSTdb,for core-genome multilocus sequence typing(cgMLST),core-genome single nucleotide polymor-phism analysis(cgSNP),virulence gene analysis,drug resistance gene prediction,and pan-genomic diversity analysis.The whole genome sequences of V.cholerae were divided into five sequence types(STs),among which the newly discovered ST182 and ST1480 were the evolutionary branches of the current dominant clonal group ST75 in China,and were highly related to two strains isolated from Taiwan in 2010 and 2013,respectively.Both toxigenic strains and non-toxigenic strains carried a variety of virulence factors and showed gene variation to varying degrees.Thirteen drug resistance genes in seven categories were predicted,among which the distribution of colistin and tetracycline resistance genes was consistent with the drug resistance phenotype.Pan-ge-nomic analysis indicated that V.cholerae had an open pan-genome,and Roary cluster analysis showed higher resolution than cgMLST.In summary,V.cholerae O1 group isolates from humans in Fujian Province have polymorphisms in genome structure and function,and the newly discovered ST1480 clone group has epidemic potential.Therefore,the monitoring of such strains must be strengthened.

In mass spectrometry-based proteomics experiments,achieving high-throughput and efficientproteolytic digestion is crucial to ensure optimal protein cleavage and enhance the depth of protein identi-fication (including the number of identified proteins and the coverage of protein amino acid sequences) .Trypsin is the most widely used protease in mass spectrometry-based proteomics due to its ability to spe-cifically cleave the carboxyl terminus of arginine and lysine.However,it was found that Trypsin has some missed enzymatic efficiency for the cleavage of lysine residues.Therefore,in actual proteomics sample preparation,a combination of Trypsin and LysC will be used to ensure adequate cleavage of lysine resi-dues.Our study revealed that the commonly employed LysC-Trypsin tandem cleavage method exerts an impact on the enzymatic cleavage of protein samples by Trypsin due to the subsequent cleavage of Trypsin by initially added LysC.Consequently,we adjusted the order of LysC and Trypsin tandem digestion,with Trypsin cleavage being performed first followed by the addition of LysC to target any missed lysine resi-dues.We comprehensively compared and analyzed three distinct sequential digestion methods,namely Trypsin-Trypsin (T-T),LysC-Trypsin (L-T),and Trypsin-LysC (T-L),in terms of their effects on pro-tein sample preparation quality.The results demonstrated that the Trypsin-LysC sequential digestion ap-proach not only minimizes missed protein lysine/arginine cleavage sites without increasing experimental costs,at the same time yielding peptides with a moderate amino acid sequence length.The use of Tryp-sin-LysC digestion enhances the adsorption and separation of peptide samples in RP-HPLC,as well as improves the depth of protein detection and amino acid sequence coverage during tandem mass spectrome-try analysis.This research work offers a novel technical solution and serves as a valuable reference for proteome sample preparation.

Aim To observe the behavioral effects of exogenous allopregnanolone(ALLO)and its inhibitor finasteride on the receptive period(R)and non-recep-tive period(NR)of PMDD liver-qi inversion model rats and the expression of GABAARα4,GABAARδ mR-NA and protein effects to explore its pathogenesis.Methods The PMDD liver-qi reverse syndrome rat model was prepared.The rats were divided into the normal group R and NR(control-R,control-NR),model group R and NR(Model-R,Model-NR),nor-mal group R+ALLO and NR+ALLO(Control+A-R,Control+A-NR),and model group R+ALLO and NR+ALLO(Model+A-R,Model+A-NR),model group R+finasteride and NR+finasteride(Model+F-R,Model+F-NR).The elevated cross labyrinth ex-periment and social interaction experiment were used to detect the behaviors of rats;fluorescence quantitative PCR and immunofluorescence were used to detect the expression of GABAARα4 and 8 mRNA and protein in rat amygdala and hippocampus.Results In the be-havioral evaluation,in the NR period,in the elevated cross maze test and in the social interaction test,the rats in the model group had anxiety behavior and de-creased social communication ability(P＜0.05),while the rats in the Model+A group could effectively relieve anxiety symptoms and improve their social com-munication ability(P＜0.05),and the rats in the Model+F group had increased anxiety behavior and social disorder(P＜0.05).In fluorescence quantita-tive PCR and immunofluorescence experiments,the ex-pression of GABAARα4 subunit in the model group was up-regulated in the hippocampus(P＜0.01),and the expression of δ subunit was down-regulated(P＜0.01);the expression of GABAARα4 subunit in the a-mygdala and hippocampus of the Model+A group de-creased(P＜0.01),and the expression of δ subunit increased in the hippocampus(P＜0.01).Conclu-sions The abnormal expression of GABAARα4 and 8 subunits mediated by ALLO improves the anxiety symptoms and social interaction ability of PMDD,which is the pathogenesis of PMDD liver-qi reverse syndrome,and provides basis and support for subse-quent exploration of the pathogenesis of PMDD liver-qi reverse syndrome.

To understand biosafety's current situation in laboratory animal research and risk factors affecting occupational health. Compliance surveys were conducted by questionnaire via Questionnaire Star (an application app on the Internet) in Chinese. Thirty-nine anonymous questionnaires were collected. The surveyed institution has established 24 types of ABSL (Animal Biosafety Laboratory) and biosafety management organizations and systems equipped with safety equipment. Our study also suggests that the principal of the laboratory establishment fails to perform supervision and inspection responsibilities, the inappropriate design of the animal biosafety laboratory, non-standardized personnel training and health management, non-strict waste management, and insufficient emergency management. The administrative department and work units should address certain safety and occupational health risks in laboratory animal research. The author proposes control strategies based on organizational guarantee, personnel management, emergency management, etc., to help prevent risks and ensure occupational health. Due to regional limitations and small sample size, the results may not be generalisable to all parts of the world. However, some of the key common issues may also be present in other regions, so we believe that this research still has some relevance.