Advances on structure, bioactivity, and biosynthesis of amino acid-containing trans-AT polyketides.

Trans-AT polyketides represent a class of natural compounds utilizing independent acyltransferase during their biosynthesis. They are well known for their diverse chemical structures and potent bioactivities. Trans-AT polyketides are synthesized through biosynthetic gene clusters predominantly composed of polyketide synthases (PKS), but often found in hybrid with non-ribosomal peptide synthetases (NRPS). This genetic hybridization results in the incorporation of amino acid residues into polyketide structures, significantly enhancing their structural diversity. Numerous amino acid-containing trans-AT polyketides have been identified, drawing significant attention to the mechanisms underlying amino acid incorporation and their impact on the biological activity of polyketides. Here, we discussed their origins, structures, biological activities, and the specific roles of amino acids in modulating both the bioactivity and biosynthesis of 38 trans-AT polyketides containing amino acids for the first time. This comprehensive analysis will serve as a crucial reference for the exploration of novel compounds and the improvement of structures and activities.

BMI1 fine-tunes gene repression and activation to safeguard undifferentiated spermatogonia fate.

Introduction: Spermatogenesis is sustained by the homeostasis of self-renewal and differentiation of undifferentiated spermatogonia throughout life, which is regulated by transcriptional and posttranscriptional mechanisms. B cell-specific Moloney murine leukemia virus integration site 1 (BMI1), one of spermatogonial stem cell markers, is a member of Polycomb repressive complex 1 (PRC1) and important to spermatogenesis. However, the mechanistic underpinnings of how BMI1 regulates spermatogonia fate remain elusive. Methods: We knocked down BMI1 by siRNA to investigate the role of BMI1 in undifferentiated spermatogonia. Differentially expressed genes were identified by RNA-seq and used for KEGG pathway analysis. We performed ChIP-seq analysis in wild type and BMI1 knockdown cells to explore the underlying molecular mechanisms exerted by BMI1. BMI1-associated alterations in repressive histone modifications were detected via Western blotting and ChIP-seq. Furthermore, we performed mass spectrometry and Co-immunoprecipitation assays to investigate BMI1 co-factors. Finally, we demonstrated the genomic regions occupied by both BMI1 and its co-factor. Results: BMI1 is required for undifferentiated spermatogonia maintenance by both repressing and activating target genes. BMI1 preserves PI3K-Akt signaling pathway for spermatogonia proliferation. Decrease of BMI1 affects the deposition of repressive histone modifications H2AK119ub1 and H3K27me3. BMI also positively regulates H3K27ac deposited genes which are associated with proliferation. Moreover, we demonstrate that BMI1 interacts with Sal-like 4 (SALL4), the transcription factor critical for spermatogonia function, to co-regulate gene expression. Discussion: Overall, our study reveals that BMI1 safeguards undifferentiated spermatogonia fate through multi-functional roles in regulating gene expression programs of undifferentiated spermatogonia.

Lipopolysaccharide and Glycolipoprotein Coordinately Triggered Necroptosis Contributes to the Pathogenesis of Leptospira Infection in Mice.

Leptospirosis is a recurring but neglected zoonotic disease caused by pathogenic Leptospira. The explicit underlying mechanism of necroptosis and its role in Leptospira infection have not yet been elucidated. Here we reported that leptospiral pathogen-associated molecular patterns, lipopolysaccharide, and glycolipoprotein activate the necroptotic RIPK1-RIPK3-MLKL cascade through the TLR4 signaling pathway in mouse macrophages. Using the murine acute leptospirosis model, we reveal that abolition of necroptosis exhibited significantly improved outcomes in acute phases, with enhanced eradication of Leptospira from liver, mild clinical symptoms, and decreased cytokine production. RIPK3 was also found to exert a necroptosis-independent function in CXCL1 production and neutrophil recruitment, with the consequence of improved Leptospira control. These findings improve our understanding of the mechanism of Leptospira-macrophage interactions, indicating potential therapeutic values by targeting necroptosis signaling pathways.

Tumor promoting long non-coding RNA CASC15 affects HMGB2 expression by sponging miR-582-5p in colorectal cancer.

BACKGROUND: The importance of long non-coding RNAs (lncRNAs) in the regulation of tumorigenesis has been gradually recognized. The roles of lncRNA cancer susceptibility candidate 15 (CASC15) in cancers have been validated by several independent groups; however, its role in colorectal cancer (CRC) remains to be explored. METHODS: Levels of CASC15 in CRC cells and normal cells were measured using a quantitative real-time polymerase chain reaction method. In vitro functional assays were performed to detect the effects of CASC15 on cell proliferation, invasion and apoptosis. Bioinformatic analyses and luciferase activity assays were conducted to investigate the targets for CASC15. Animal experiments were conducted to analyze the effect of CASC15 on tumor growth in vivo. RESULTS: The CASC15 level is revealed to be significantly elevated in CRC cells compared to that in normal cells. In vitro assays revealed that CASC15 overexpression stimulates cell growth and invasion, whereas its down-expression has opposite effects. Furthermore, CASC15 can bind with microRNA-582-5p (miR-582-5p) to modulate high mobility group box 2 (HMGB2) expression. We also showed that silencing of CASC15 inhibits tumor growth. CONCLUSIONS: In summary, CASC15 overexpression could promote CRC carcinogenesis, indicating that knockdown of CASC15 might be a possible therapeutic measure to hinder carcinogenesis. The results of the present study could help us to understand the mechanisms behind CRC progression.

Scavenger receptor A1 participates in uptake of Leptospira interrogans serovar Autumnalis strain 56606v and inflammation in mouse macrophages.

Leptospirosis, caused by pathogenic Leptospira species, has emerged as a widespread zoonotic disease worldwide. Macrophages mediate the elimination of pathogens through phagocytosis and cytokine production. Scavenger receptor A1 (SR-A1), one of the critical receptors mediating this process, plays a complicated role in innate immunity. However, the role of SR-A1 in the immune response against pathogenic Leptospira invasion is unknown. In the present study, we found that SR-A1 is an important nonopsonic phagocytic receptor on murine macrophages for Leptospira. However, intraperitoneal injection of leptospires into WT mice presented with more apparent jaundice, subcutaneous hemorrhaging, and higher bacteria burdens in blood and tissues than that of SR-A1-/- mice. Exacerbated cytokine and inflammatory mediator levels were also observed in WT mice and higher recruited macrophages in the liver than those of SR-A1-/- mice. Our findings collectively reveal that although beneficial in the uptake of Leptospira by macrophage, SR-A1 might be exploited by Leptospira to modulate inflammatory activation and increase the susceptibility of infection in the host. These results provide our new insights into the innate immune response during early infection by L. interrogans.

Effects of human ß-defensin 3 fused with carbohydrate-binding domain on the function of type III secretion system in Pseudomonas aeruginosa PA14.

Antimicrobial peptides are considered to be one of the candidate antimicrobial agents for antibiotic-resistant bacterial infection in the future. The effects of antimicrobial peptide hBD3-CBD on Pseudomonas aeruginosa PA14 and PA14 ΔexsA were analyzed by the bactericidal effects, hemolysis assays, pyocyanin pigment productions, and virulence factor expressions (exoU, exoS, hcnA, and lasB). Pyocyanin production and virulence factor expressions are important features of the type III secretion system in Pseudomonas aeruginosa. HBD3-CBD killed PA14 and PA14 ΔexsA with similar efficiency; it lowered the hemolysis levels of PA14 and PA14 ΔexsA and reduced the pyocyanin production, biofilm formation, and exoU, exoS, and lasB expressions in PA14. Compared with PA14, PA14 ΔexsA showed a lower hemolysis effect, pyocyanin production, exoU, and lasB expressions. The effects of hBD3-CBD on the PA14 toxin secretion were similar to the changes in the type III secretion system mutant isolate PA14 ΔexsA. Our results demonstrated that the type III secretion system was involved in the biological functions on PA 14 from hBD3-CBD.

Waveform analysis of differential graphs of reconstructed impedance cardiography from healthy individuals.

PURPOSE: The aim is to measure and analyze the wave amplitudes and time intervals of differential graphs of reconstructed impedance cardiography (RICG). METHODS: 180 adults with normal cardiac function between the ages of 18-78 were included in the study. Six mingled impedance changes on chest surface were simultaneously detected for each subject. The differential graphs of five impedance change components of RICG were obtained through waveform separation and software differentiation. The amplitudes of C, X, O, b waves and time intervals of Q-b and Q-C were measured and statistically analyzed. RESULTS: The amplitudes of C and X waves in PL, PR, AO, and that of C, O, b waves in LV and RV, all decrease as age increases. Wave amplitudes of the female group were bigger than those of the male group (p < .01), while the Q-C intervals of the female group were shorter than that of the male group (p < .01). Among five impedance change components, the wave amplitude of AO was larger than those of PL and PR (p < .01), and wave amplitudes of PL and PR were bigger than those of LV and RV (p < .01). Q-C intervals of LV and RV were longer than those of AO, PL and PR (p < .01), while the Q-b intervals of LV and RV were shorter than the Q-C intervals of AO, PL, and PR. CONCLUSIONS: The differential graphs of RICG could reflect indirectly the physiological activities and pathological changes of the heart and of the large blood vessels in thorax.

A Novel Polysaccharide Depolymerase Encoded by the Phage SH-KP152226 Confers Specific Activity Against Multidrug-Resistant Klebsiella pneumoniae via Biofilm Degradation.

The increasing prevalence of infections caused by multidrug-resistant Klebsiella pneumoniae necessitates the development of alternative therapies. Here, we isolated, characterized, and sequenced a K. pneumoniae bacteriophage (SH-KP152226) that specifically infects and lyses K. pneumoniae capsular type K47. The phage SH-KP152226 contains a genome of 41,420 bp that encodes 48 predicted proteins. Among these proteins, Dep42, the gene product of ORF42, is a putative tail fiber protein and hypothetically possesses depolymerase activity. We demonstrated that recombinant Dep42 showed specific enzymatic activities in the depolymerization of the K47 capsule of K. pneumoniae and was able to significantly inhibit biofilm formation and/or degrade formed biofilms. We also showed that Dep42 could enhance polymyxin activity against K. pneumoniae biofilms when used in combination with antibiotics. These results suggest that combination of the identified novel depolymerase Dep42, encoded by the phage SH-KP152226, with antibiotics may represent a promising strategy to combat infections caused by drug-resistant and biofilm-forming K. pneumoniae.

Mitogen-stimulated cell proliferation and cytokine production in major depressive disorder patients.

BACKGROUND: Major depressive disorder (MDD) is related to human's immune status, and immunological indicators such as mitogen stimulated cell proliferation and cytokines may become candidate biomarkers for disease diagnosis. METHODS: One hundred diagnosed major depressive disorder subjects and 100 health controls were enrolled in this study. Phytohaemagglutinin and lipopolysaccharide stimulated cell proliferations and cytokine concentrations were detected in peripheral blood mononuclear cells from both groups. The corresponding stimulated responses were conducted and confirmed in chronic unpredictable mild stress (CUMS) mice. RESULTS: Compared to the people in control group, there were lower cell proliferations and lower TNF-α produced in lipopolysaccharide stimulated peripheral blood mononuclear cells in depression patients, lower IL-2 and IL-10 produced in phytohaemagglutinin stimulated peripheral blood mononuclear cells in depression patients, higher IL-6, IL-10 and lower IL-2 secretions were detected in peripheral plasma in depression patients. In CUMS mice we found lower splenocyte proliferations, lower IL-1α productions and higher IL-6 secretions in lipopolysaccharide stimulated splenocytes. It seems lipopolysaccharide stimulated cell proliferation activities were inhibited in depressive states. CONCLUSIONS: Lower lipopolysaccharide stimulated cell proliferation and phytohaemagglutinin stimulated or plasma cytokine IL-2 decreases should be potential monitoring indices in the depressive state assessment for major depressive disorder patients.

Influence of ultrasonic waves on the removal of different oil components from oily sludge.

Ultrasonic technology is a promising tool for washing oily sludge to recover oil. In this study, the influence of ultrasonic conditions on the removal of different oil components from oily sludge was investigated to optimize ultrasonic washing technology. Among the three frequencies (25, 50 and 100 kHz) applied, ultrasonic washing at 25 kHz exhibited the best performance in terms of oil extraction rate and efficiency. An ultrasonic intensity of 0.33 W/cm2 was necessary to overcome the energy threshold for oil washing. Application of a standing wave or dual frequencies did not improve the oil removal performance perceptibly. The optimum conditions for the removal of oil from oily sludge were an ultrasonic frequency of 25 kHz, intensity of 0.33 W/cm2 and sludge/water ratio of 1/2 (in volume). Thin-layer chromatographic flame ionization detection showed that ultrasonication could overcome high energy thresholds, resulting in an increase in the removal of asphaltenes and resins, with the removal of asphaltenes particularly affected by frequency. This study could provide valuable information for the application of ultrasonic technology in oily sludge treatment.

Microbial abundance and community composition influence production performance in a low-temperature petroleum reservoir.

Enhanced oil recovery using indigenous microorganisms has been successfully applied in the petroleum industry, but the role of microorganisms remains poorly understood. Here, we investigated the relationship between microbial population dynamics and oil production performance during a water flooding process coupled with nutrient injection in a low-temperature petroleum reservoir. Samples were collected monthly over a two-year period. The microbial composition of samples was determined using 16S rRNA gene pyrosequencing and real-time quantitative polymerase chain reaction analyses. Our results indicated that the microbial community structure in each production well microhabitat was dramatically altered during flooding with eutrophic water. As well as an increase in the density of microorganisms, biosurfactant producers, such as Pseudomonas, Alcaligenes, Rhodococcus, and Rhizobium, were detected in abundance. Furthermore, the density of these microorganisms was closely related to the incremental oil production. Oil emulsification and changes in the fluid-production profile were also observed. In addition, we found that microbial community structure was strongly correlated with environmental factors, such as water content and total nitrogen. These results suggest that injected nutrients increase the abundance of microorganisms, particularly biosurfactant producers. These bacteria and their metabolic products subsequently emulsify oil and alter fluid-production profiles to enhance oil recovery.

X-ray characteristics of posterolateral rotatory instability of the elbow caused by ligament injury / 中国骨伤

<p><b>OBJECTIVE</b>To study the role of lateral collateral ligament complex on the posterolateral rotatory instability and the relationship between the radiocapitellar ratio (RCR) and the injury of lateral collateral ligament complex on X-ray images.</p><p><b>METHODS</b>Twenty elbow joints from fresh-frozen adult cadavers were used to make osteo-ligamentous elbow specimens. The specimens were fixed with a self-made device to maintain posterolateral rotatory instability of the elbow joint. All the specimens were divided into two groups: group A and group B. Surgical procedures were carried out as follows in the lateral structures of group A: A1, intact specimen; A2, transection of radial ulnar collateral ligament firstly; A3, transection of annular ligament secondly; A4, final transection of the radial collateral ligament. The procedures in group B were carried out as follows: B1, intact specimen; B2, transection of the radial collateral ligament firstly; B3, transection of the annular ligament secondly; B4, final transection of the radial ulnar collateral ligament. Lateral X-ray films of elbow joint were taken, and the radiocapitellar ratio (RCR) was measured by using PACS. All analysis was performed with SPSS 17.0 software.</p><p><b>RESULTS</b>Group A: the increases in RCR had statistical differences among A1, A2, A3, and A4 groups. Group B: the increases in RCR had no statistical differences among B1, B2 and B3 groups; but the increase in RCR in group B4 was more than that in B1, B2 and B3 groups.</p><p><b>CONCLUSION</b>The radial ulnar collateral ligament is a key structure to maintain posterolateral rotatory stability;the radial collateral ligament and the annular ligament are the secondary important structures. There are 4 grades of the posterolateral rotatory instability of the elbow, according to the X-ray imaging classification.</p>