Progress on H2B as a multifunctional protein related to pathogens.

Histone H2B is a member of the core histones, which together with other histones form the nucleosome, the basic structural unit of chromosomes. As scientists delve deeper into histones, researchers gradually realize that histone H2B is not only an important part of nucleosomes, but also plays a momentous role in regulating gene transcription, acting as a receptor and antimicrobial action outside the nucleus. There are a variety of epigenetically modified sites in the H2B tail rich in arginine and lysine, which can occur in ubiquitination, phosphorylation, methylation, acetylation, etc. When stimulated by foreign factors such as bacteria, viruses or parasites, histone H2B can act as a receptor for the recognition of these pathogens, and induce an intrinsic immune response to enhance host defense. In addition, the extrachromosomal histone H2B is also an important anti-microorganism agent, which may be the key to the development of antibiotics in the future. This review aims to summarize the interaction between histone H2B and etiological agents and explore the role of H2B in epigenetic modifications, receptors and antimicrobial activity.

The effects of CypA on apoptosis: potential target for the treatment of diseases.

Cyclophilin A (CypA), the first member of cyclophilins, is distributed extensively in eukaryotic and prokaryotic cells, primarily localized in the cytoplasm. In addition to acting as an intracellular receptor for cyclosporin A (CSA), CypA plays a crucial role in diseases such as aging and tumorigenesis. Apoptosis, a form of programmed cell death, is able to balance the rate of cell viability and death. In this review, we focus on the effects of CypA on apoptosis and the relationship between specific mechanisms of CypA promoting or inhibiting apoptosis and diseases, including tumorigenesis, cardiovascular diseases, organ injury, and microbial infections. Notably, the process of CypA promoting or inhibiting apoptosis is closely related to disease development. Finally, future prospects for the association of CypA and apoptosis are discussed, and a comprehensive understanding of the effects of CypA on apoptosis in relation to diseases is expected to provide new insights into the design of CypA as a therapeutic target for diseases. KEY POINTS: • Understand the effect of CypA on apoptosis. • CypA affects apoptosis through specific pathways. • The effect of CypA on apoptosis is associated with a variety of disease processes.

Transcriptome analysis of the hepatopancreas from the Litopenaeus vannamei infected with different flagellum types of Vibrio alginolyticus strains.

Vibrio alginolyticus, one of the prevalently harmful Vibrio species found in the ocean, causes significant economic damage in the shrimp farming industry. Its flagellum serves as a crucial virulence factor in the invasion of host organisms. However, the processes of bacteria flagella recognition and activation of the downstream immune system in shrimp remain unclear. To enhance comprehension of this, a ΔflhG strain was created by in-frame deletion of the flhG gene in V. alginolyticus strain HN08155. Then we utilized the transcriptome analysis to examine the different immune responses in Litopenaeus vannamei hepatopancreas after being infected with the wild type and the mutant strains. The results showed that the ΔflhG strain, unlike the wild type, lost its ability to regulate flagella numbers negatively and displayed multiple flagella. When infected with the hyperflagella-type strain, the RNA-seq revealed the upregulation of several immune-related genes in the shrimp hepatopancreas. Notably, two C-type lectins (CTLs), namely galactose-specific lectin nattectin and macrophage mannose receptor 1, and the TNF receptor-associated factor (TRAF) 6 gene were upregulated significantly. These findings suggested that C-type lectins were potentially involved in flagella recognition in shrimp and the immune system was activated through the TRAF6 pathway after flagella detection by CTLs.

Long-term straw return improves cooked indica rice texture by altering starch structural, physicochemical properties in South China.

Straw return can improve rice eating quality by modifying starch formation from long-term field trials, whereas the relevant mechanisms are still unknown. A long-term field experiment, including straw removal (CK), straw burning return (SBR), and straw return (SR) was conducted to investigate the starch structure, physicochemical properties, and cooked rice textures of indica early- and late-rice. Compared with CK, SBR and SR enhanced relative crystallinity, amylopectin long chains in both rice seasons, and gelatinization temperatures in late rice. Compared to SBR, SR decreased protein content and amylopectin short chains but increased starch branching degree, breakdown, and stickiness, ultimately contributing to improved starch thermal and pasting properties. Meanwhile, SR decreased hardness, cohesiveness, and chewiness, resulting in cooked texture meliorated, which was mainly attributed to amylopectin chain length and starch granule size. The results suggest that SR increased cooked texture of indica rice by altering starch structural and physicochemical properties.

Bioinformatic and functional characterization of cyclic-di-GMP metabolic proteins in Vibrio alginolyticus unveils key diguanylate cyclases controlling multiple biofilm-associated phenotypes.

The biofilm lifestyle is critical for bacterial survival and proliferation in the fluctuating marine environment. Cyclic diguanylate (c-di-GMP) is a key second messenger during bacterial adaptation to various environmental signals, which has been identified as a master regulator of biofilm formation. However, little is known about whether and how c-di-GMP signaling regulates biofilm formation in Vibrio alginolyticus, a globally dominant marine pathogen. Here, a large set of 63 proteins were predicted to participate in c-di-GMP metabolism (biosynthesis or degradation) in a pathogenic V. alginolyticus strain HN08155. Guided by protein homology, conserved domains and gene context information, a representative subset of 22 c-di-GMP metabolic proteins were selected to determine which ones affect biofilm-associated phenotypes. By comparing phenotypic differences between the wild-type and mutants or overexpression strains, we found that 22 c-di-GMP metabolic proteins can separately regulate different phenotypic outputs in V. alginolyticus. The results indicated that overexpression of four c-di-GMP metabolic proteins, including VA0356, VA1591 (CdgM), VA4033 (DgcB) and VA0088, strongly enhanced rugose colony morphotypes and strengthened Congo Red (CR) binding capacity, both of which are indicators of biofilm matrix overproduction. Furthermore, rugose enhanced colonies were accompanied by increased transcript levels of extracellular polysaccharide (EPS) biosynthesis genes and decreased expression of flagellar synthesis genes compared to smooth colonies (WTpBAD control), as demonstrated by overexpression strains WTp4033 and ∆VA4033p4033. Overall, the high abundance of c-di-GMP metabolic proteins in V. alginolyticus suggests that c-di-GMP signaling and regulatory system could play a key role in its response and adaptation to the ever-changing marine environment. This work provides a robust foundation for the study of the molecular mechanisms of c-di-GMP in the biofilm formation of V. alginolyticus.

Starch multiscale structure and physicochemical property alterations in high-quality indica rice quality and cooked rice texture under different nitrogen panicle fertilizer applications.

The starch multiscale structure, physiochemical properties, grain quality and cooked rice texture of high-quality early and late indica were analyzed under nitrogen panicle fertilizer (low panicle fertilizer, LPF; middle panicle fertilizer, MPF; high panicle fertilizer, HPF) treatments and their internal relations were investigated. Compared to the MPF treatment, the starch granules in HPF and LPF had more surface-proteins and irregular voids for high-quality early and late indica rice cultivars, respectively. Nitrogen panicle fertilization application increased amylopectin medium and long chains as well as protein content, resulting in higher relative crystallinity and gelatinization temperatures. Moderate changes in starch multistructures and physicochemical properties such as branching degree, amylopectin medium chain, and pasting viscosities derived from MPF treatment significantly improved processing, appearance qualities and cooked rice texture. Additionally, the decrease in starch branching, gelatinization temperatures, and granule uniformity along with an increase in large granules, breakdown, and △Hgel under MPF treatment were the main reasons for improving rice textural properties.

Grain yield and quality performances of different late-season rice cultivars in response to experimental warming in subtropical China.

Introduction: Climate warming has pronounced effects on rice production in China. However, late-seasons rice cultivars are diverse in double rice cropping systems, and the actual responses in grain yield and quality of different late-season rice cultivars to climate warming are still unclear. Methods: A two-year field warming experiment was conducted by using free-air temperature increase facilities with three widely-planted late-season rice cultivars, including Taiyou398 (TY, short growth duration indica hybrid rice), Jiuxiangnian (JXN, long growth duration indica inbred rice), and Yongyou1538 (YY, long growth duration indica-japonica hybrid rice) in a double rice cropping system in subtropical China. Results: Warming (1.9-2.0°C) had no significant effects on the grain yields of TY and JXN, but significantly decreased that of YY by 4.8% relative to ambient treatment due to a reduction of spikelet number. Compared to ambient treatment, the head rice yields of TY and YY did not change while that of JXN increased by 6.3% under warming conditions. Warming significantly increased the head rice rates of JXN and YY by 6.6% and 7.8%, and the chalky grain rates of TY, JXN, and YY by 79.1%, 21.6%, and 7.6%, respectively. Under warming conditions, the amylose content of JXN and YY decreased significantly by 7.5% and 8.8%, and the setback of three cultivars decreased significantly by an average of 41.5%. Conclusion: Warming could improve the milling and eating qualities of long growth duration late-season rice (JXN and YY) and increase or maintain their head rice yield, even though decreased the grain yield of indica-japonica hybrid rice (YY). These results will provide a better understanding for the selection of suitable late-season rice cultivars under future climate warming conditions.

Mycoplasma genitalium Protein of Adhesion Suppresses T Cell Activation via CypA-CaN-NFAT Pathway.

Mycoplasma genitalium is a prokaryotic microorganism that causes urogenital tract infections. M. genitalium protein of adhesion (MgPa) was essential for M. genitalium attachment and subsequent invasion into host cells. Our prior research confirmed that Cyclophilin A (CypA) was the binding receptor for MgPa and MgPa-CypA interaction can lead to the production of inflammatory cytokines. In this study, we revealed that the recombinant MgPa (rMgPa) could inhibit the CaN-NFAT signaling pathway to reduce the level of IFN-γ, IL-2, CD25, and CD69 in Jurkat cells by binding to the CypA receptor. Moreover, rMgPa inhibited the expressions of IFN-γ, IL-2, CD25, and CD69 in primary mouse T cells. Likewise, the expressions of these T cells activation-related molecules in CypA-siRNA-transfected cells and CypA-/- mouse primary T cell was strengthened by rMgPa. These findings showed that rMgPa suppressed T cell activation by downregulating the CypA-CaN-NFAT pathway, and as a result, acted as an immunosuppressive agent. IMPORTANCE Mycoplasma genitalium is a sexually transmitted bacterium that can co-infect with other infections and causes nongonococcal urethritis in males, cervicitis, pelvic inflammatory disease, premature birth, and ectopic pregnancy in women. The adhesion protein of M. genitalium (MgPa) is the primary virulence factor in the complicated pathogenicity of M. genitalium. This research proved that MgPa could interact with host cell Cyclophilin A (CypA) and prevent T cell activation by inhibiting Calcineurin (CaN) phosphorylation and NFAT nuclear translocation, which clarified the immunosuppression mechanism of M. genitalium to host T cells. Therefore, this study can provide a new idea that CypA can be used for a therapeutic or prophylactic target for M. genitalium infection.

Vimentin Is an Attachment Receptor for Mycoplasma pneumoniae P1 Protein.

Mycoplasma pneumoniae is the most common pathogen causing respiratory tract infection, and the P1 protein on its adhesion organelle plays a crucial role during the pathogenic process. Currently, there are many studies on P1 and receptors on host cells, but the adhesion mechanism of P1 protein is still unclear. In this study, a modified virus overlay protein binding assay (VOPBA) and liquid chromatography-mass spectrometry (LC-MS) were performed to screen for proteins that specifically bind to the region near the carboxyl terminus of the recombinant P1 protein (rP1-C). The interaction between rP1-C and vimentin or ß-4-tubulin were confirmed by far-Western blotting and coimmunoprecipitation. Results verified that vimentin and ß-4-tubulin were mainly distributed on the cell membrane and cytoplasm of human bronchial epithelial (BEAS-2B) cells, but only vimentin could interact with rP1-C. The results of the adhesion and adhesion inhibition assays indicated that the adhesion of M. pneumoniae and rP1-C to cells could be partly inhibited by vimentin and its antibody. When vimentin was downregulated with the corresponding small interfering RNA (siRNA) or overexpressed in BEAS-2B cells, the adhesion of M. pneumoniae and rP1-C to cells was decreased or increased, respectively, which indicated that vimentin was closely associated with the adhesion of M. pneumoniae and rP1-C to BEAS-2B cells. Our results demonstrate that vimentin could be a receptor on human bronchial epithelial cells for the P1 protein and plays an essential role in the adhesion of M. pneumoniae to cells, which may clarify the pathogenesis of M. pneumoniae. IMPORTANCE Mycoplasma pneumoniae is the most common pathogen causing respiratory tract infection, and the P1 protein on its adhesion organelle plays a crucial role during the pathogenic process. A variety of experiments, including enzyme-linked immunosorbent assay (ELISA), coimmunoprecipitation, adhesion, and adhesion inhibition assay, have demonstrated that the M. pneumoniae P1 protein can interact with vimentin, that the adhesion of M. pneumoniae and recombinant P1 protein to BEAS-2B cells was affected by the expression level of vimentin. This provides a new idea for the prevention and treatment of Mycoplasma pneumoniae infection.

Low temperature and light combined stress after heading on starch fine structure and physicochemical properties of late-season indica rice with different grain quality in southern China.

Late-season indica rice frequently encounters low temperature (LT) along with low light (LL) after heading in southern China, which deteriorates the grain quality by altering starch quality. However, the detailed effects on starch properties of these stressors remain unclear. Herein, two indica rice cultivars with good and poor grain quality were grown under control (CK), LT, and LT + LL conditions after heading and the structural and physicochemical properties of their starch were evaluated. Compared with CK, LT and LT + LL worsened thermal and pasting properties of starch in the two cultivars, mainly because they increased branch chain branching and A chain (DP ≤12), and decreased average branch chain length and crystallinity. Compared with LT, LT + LL deteriorated the pasting properties of the poor-quality cultivar, such as reducing breakdown (BD), final and peak viscosity, which mainly owing to decreasing the starch branching and crystallinity degrees, and increasing the small starch granules (d < 10 µm). Gelatinization enthalpy and BD both had significant and positive correlations with amylose content, the ratio of amylose and amylopectin, B3 chain and crystallinity. Taken together, these results suggest that LT and LT + LL during grain filling can deteriorate the physicochemical properties of starch in late-season indica rice cultivars by disrupting starch multilevel structure, especially upon LT + LL. In particular, while poor-quality cultivar had poorer physicochemical properties, the good-quality cultivar had poorer thermal properties under LT + LL.

Interactive effects of water management and liming on CH4 emissions and rice cadmium uptake in an acid paddy soil.

Rice agriculture is both an important source of the potent greenhouse gas methane (CH4) and a bioaccumulator of cadmium (Cd), which is hazardous to human health. Avoiding flooding during rice production is effective for reducing CH4 emissions, but it increases rice Cd uptake. Although lime application decreases Cd concentration in rice grains, it is not clear whether combining appropriate water management with liming can simultaneously reduce CH4 emissions and Cd uptake in rice paddies. Thus, a pot experiment was performed to investigate the interactive effects of water management (F: continuous flooding, FDF: flooding - midseason drainage - flooding, FDI: flooding - midseason drainage - intermittent irrigation) and lime application on CH4 emissions and rice Cd uptake in an acid paddy soil spiked with Cd. Results showed that neither water management nor liming significantly affected grain yield. Overall, liming reduced CH4 emissions by 42.2%. Compared to F, the FDF and FDI treatments reduced CH4 emissions by 43.5% and 54.2%, respectively. Liming reduced CH4 emissions by 32.6% under F, but with a greater decrease of 48.6% and 52.7% under FDF and FDI, respectively. Overall, liming reduced rice Cd uptake by an average of 47.3%. Compared to FDI, F and FDF significantly reduced Cd uptake by 84.0% and 75.1%, respectively, but there was no significant difference between F and FDF. Liming did not significantly affect Cd uptake under F and FDF, whereas liming reduced Cd uptake by 55.9% under FDI. These results suggest that maintaining flooding following midseason drainage can help in reducing rice Cd uptake, though slightly promoting CH4 emissions. Therefore, we recommend FDF combined with liming to mitigate CH4 emissions without increasing rice Cd uptake in acid paddy soils.

Histones: The critical players in innate immunity.

The highly conserved histones in different species seem to represent a very ancient and universal innate host defense system against microorganisms in the biological world. Histones are the essential part of nuclear matter and act as a control switch for DNA transcription. However, histones are also found in the cytoplasm, cell membranes, and extracellular fluid, where they function as host defenses and promote inflammatory responses. In some cases, extracellular histones can act as damage-associated molecular patterns (DAMPs) and bind to pattern recognition receptors (PRRs), thereby triggering innate immune responses and causing initial organ damage. Histones and their fragments serve as antimicrobial peptides (AMPs) to directly eliminate bacteria, viruses, fungi, and parasites in vitro and in vivo. Histones are also involved in phagocytes-related innate immune response as components of neutrophil extracellular traps (NETs), neutrophil activators, and plasminogen receptors. In addition, as a considerable part of epigenetic regulation, histone modifications play a vital role in regulating the innate immune response and expression of corresponding defense genes. Here, we review the regulatory role of histones in innate immune response, which provides a new strategy for the development of antibiotics and the use of histones as therapeutic targets for inflammatory diseases, sepsis, autoimmune diseases, and COVID-19.

Screening of bioflocculant and cellulase-producing bacteria strains for biofloc culture systems with fiber-rich carbon source.

The biofloc technology (BFT) system has been widely applied in the shrimp and fish culture industry for its advantages in water-saving, growth improvement, and water quality purification. However, The BFT system usually takes a long time to establish, and the extra carbon source input increases the maintenance cost of the system. In this study, we aimed to develop a low-cost and high-efficient BFT system for Litopenaeus vannamei by applying bacteria that could promote the formation of BFT and utilize cheap carbon sources. Three bioflocculant-producing bacteria strains (M13, M15, and M17) have been screened from a cellulolytic strain collection. All three strains have been identified as Bacillus spp. and can use sugarcane bagasse (SB) as a carbon source, which is a cheap byproduct of the sucrose industry in the tropic area of China. Compared to sucrose, the addition of SB and the three strains could improve the biofloc formation rate, biofloc size distribution, ammonia removal rate, and the growth performance of the shrimps. These results suggest that the bioflocculant and cellulase-producing bacteria strains could promote the biofloc formation and the growth of shrimps by using SB as an economic substitute carbon source in the BFT shrimp culture system.

Prevalence of Bacterial Coinfections with Vibrio harveyi in the Industrialized Flow-through Aquaculture Systems in Hainan Province: A Neglected High-Risk Lethal Causative Agent to Hybrid Grouper.

Vibrio harveyi is one of the most serious bacterial pathogens to aquatic animals worldwide. Evidence is mounting that coinfections caused by multiple pathogens are common in nature and can alter the severity of diseases in marine animals. However, bacterial coinfections involving V. harveyi have received little attention in mariculture. In this study, the results of pathogen isolation indicated that bacterial coinfection was a common and overlooked risk for hybrid groupers (♀ Epinephelus polyphekadion × â™‚ E. fuscoguttatus) reared in an industrialized flow-through pattern in Hainan Province. The artificial infection in hybrid groupers revealed that coinfections with V. harveyi strain GDH11385 (a serious lethal causative agent to groupers) and other isolated pathogens resulted in higher mortality (46.67%) than infection with strain GDH11385 alone (33.33%), whereas no mortality was observed in single infection with other pathogens. Furthermore, the intestine, liver and spleen of hybrid groupers are target organs for bacterial coinfections involving V. harveyi. Based on the infection patterns found in this study, we propose that V. harveyi may have a specific spatiotemporal expression pattern of virulence genes when infecting the host. Taken together, bacterial coinfection with V. harveyi is a neglected high-risk lethal causative agent to hybrid groupers in the industrialized flow-through aquaculture systems in Hainan Province.

Analysis of the Antioxidant Composition of Low Molecular Weight Metabolites from the Agarolytic Bacterium Alteromonas macleodii QZ9-9: Possibilities for High-Added Value Utilization of Macroalgae.

Agar accounts for ~60% of the dry weight of some red macroalgae, and the breakdown of this kind of polysaccharide releases high-value compounds; therefore, the resource utilization of agar is of great significance to improve the added value of these macroalgae. Herein, Alteromonas macleodii QZ9-9 isolated from tropical Gracilaria hainanensis in Hainan Island was characterized as an agarolytic bacterium, which displayed a high agar-degrading activity. The highest diameters of the degradation zones of the A. macleodii QZ9-9 and its extracellular-agarase (12.16 U/mL) were 41.46 mm and 22.89 mm, respectively, and the first-order degradation rate constants of those were 0.02 h-1 and 0.77 U-1, respectively. Importantly, the fermentation products of A. macleodii QZ9-9 exhibited antioxidant activity, and the peak of DPPH scavenging activity of 50 h fermentation products of this strain was up to 50.79% in the reaction for 1 h; the DPPH scavenging activity of low molecule metabolites (≤3 kDa) in particular was up to ~85.85%. A total of 766 metabolites were detected in the low molecule metabolites by metabolomics. The peptide-like metabolites, such as prolyl-histidine, isoleucyl-histidine, isoleucyl-proline and arginyl-proline, and the antioxidant maculosin were found in the top 20 metabolites with relatively high abundance. Additionally, the antioxidant activity of maculosin was further verified in this work. We concluded that the low molecule metabolites of A. macleodii QZ9-9 with relatively high antioxidant activity are interesting candidates for preparing desirable non-toxic antioxidants, thereby facilitating the high value-added utilization of macroalgae in the fields of cosmetic, food preservation, and pharmaceutical industries.

Multi-Costimulatory Pathways Drive the Antagonistic Pseudoalteromonas piscicida against the Dominant Pathogenic Vibrio harveyi in Mariculture: Insights from Proteomics and Metabolomics.

Vibrio harveyi is the dominant pathogen in mariculture, and biocontrol of this pathogen using antagonistic probiotics is a long-standing biological challenge. Here, Pseudoalteromonas piscicida WCPW15003 as a probiotic effectively antagonized dominant pathogenic V. harveyi in a mariculture, with a growth-of-inhibition ratio of 6.3 h-1. The antagonistic activities of cells and intracellular components of WCPW15003 made a greater contribution to the antagonistic process than did extracellular metabolites and caused the dominance of WCPW15003 during the antagonistic process in vitro. WCPW15003 was safe for the pearl gentian grouper (♀ Epinephelus fuscoguttatus × â™‚ Epinephelus lanceolatus) and, as a consequence of the antagonistic effect on V. harveyi, protected the fish from an immune response in vivo. A comprehensive combined proteomics and metabolomics analysis of antagonistic WCPW15003 and pathogenic V. harveyi in a coculture compared to a monoculture was performed to investigate the antagonistic molecular mechanisms. The results showed that during the antagonistic process, WCPW15003 in a coculture had significantly downregulated metabolic pathways for histidine metabolism, arginine biosynthesis, and phenylalanine metabolism, and upregulated glycerophospholipid metabolism, leading to a competitive advantage against the co-occurring species, V. harveyi. This defined a mechanism by which multi-costimulatory pathways drove P. piscicida WCPW15003 against V. harveyi. IMPORTANCE V. harveyi as a dominant pathogen has become a major hazard in mariculture development and seafood safety, and biocontrol of this pathogen using antagonistic probiotic agents is a long-standing biological challenge. P. piscicida WCPW15003 has promise as a novel, safe, and effective bioagent for specifically inhibiting dominant pathogenic V. harveyi and protects mariculture animals from infection by this pathogen by moderating the host immune response, which is heavily driven by multi-costimulatory pathways in a coculture of WCPW15003 and V. harveyi. This work identified a direction for comprehensively elucidating the molecular mechanism of WCPW15003 antagonism against the dominant pathogen in mariculture using modern molecular biology techniques and provided deep insights into the advantages and potential of this antagonistic probiotic against V. harveyi for the construction of an environmentally friendly, recirculating mariculture system.

Cross-habitat distribution pattern of Bacillus communities and their capacities of producing industrial hydrolytic enzymes in Paracel Islands: Habitat-dependent differential contributions of the environment.

Bacillus as a predominant genus of enzyme-producing bacteria presents desirable features to fulfill the vast demand of specific industries, whereas the knowledge of the Bacillus communities and their capacities of producing industrial hydrolytic enzymes across the microhabitats of the Paracel Islands is limited. Herein, a total of 193 culturable Bacillus strains belonging to 19 species were isolated across the microhabitats of seawater, sediment, coral and seagrass, covering 39 stations of the Paracel Islands. Each microhabitat displayed its unique species, while the species of Bacillus paramycoides besides being the dominant species with an abundance of 54.94% also was the only species shared by all microhabitats of the Paracel Islands. Of the Bacillus communities, 97.41% of the isolates exhibited the capacity of producing one-or-more types of enzymes with comparatively higher and broader ranges of enzyme activities, including 163 protease-, 27 cellulase-, 118 alginate lyase-, 140 K-carrageenase- and 158 agarose-producing strains. By the correlation analyses of "Bacillus-environmental factors" and "Enzyme-producing Bacillus-environmental factors", the cross-habitat distribution and enzyme-producing capacity pattern of the Bacillus communities were strongly driven by habitat type, and the environmental factors made habitat-dependent differential contributions to that in the Paracel Islands. It's worth noting that the cellulase-producing strain wasn't detected in seagrass due to its survival strategy to prevent cellulose degradation by inhibiting cellulase-producing bacteria, while coral contained more stable microbial metabolic functions to protect against environmental fluctuations. These findings besides providing large quantities of promising enzyme-producing candidates for specific industrial desires, also facilitate the development and utilization of marine microbial resources and the environmental policy- and/or law-making according to environmental features across the microhabitats of the Paracel Islands.

The adhesion protein of Mycoplasma genitalium inhibits urethral epithelial cell apoptosis through CypA-CD147 activating PI3K/ Akt/NF-κB pathway.

By interacting with the receptor on the host cells membrane, Mycoplasma genitalium, a prokaryotic bacterium primarily transmitted through sexual contact, can adhere to and even enter cells. The adhesion protein of M. genitalium (MgPa) plays a critical function in the adhering and subsequent invasion into host cells. Our prior studies verified that cyclophilin A (CypA) was the receptor of MgPa on human urethral epithelial cells (SV-HUC-1) membrane and could induce pro-inflammatory cytokines production through the CypA-CD147-ERK-NF-κB pathway. This research aims to understand how MgPa interacts with its membrane receptor CypA to cause apoptosis in host cells. We employed flow cytometry to see if MgPa prevents or enhances apoptosis of SV-HUC-1 cells. The apoptosis-related proteins such as Bax, caspase-3, and cleaved caspase-3 were assayed using Western blot. Results suggested that MgPa could inhibit the apoptosis of SV-HUC-1 cells. And we demonstrated that interference with the expression of CypA or CD147 significantly reversed the inhibitory effect of MgPa on SV-HUC-1 cells apoptosis, indicating that MgPa inhibited urothelial cells apoptosis through CypA/CD147. Furthermore, we discovered that MgPa regulates the PI3K/Akt/NF-κB pathway through CypA/CD147 to inhibit SV-HUC-1 cells apoptosis. Ultimately, the inhibitory effect of MgPa on the apoptosis of the urothelial epithelial cells extracted from CypA-knockout mice was validated by Annexin V/PI assay. The results corroborated that MgPa could also inhibit mouse urothelial epithelial cells apoptosis. In summary, we demonstrated that MgPa could inhibit SV-HUC-1 cells apoptosis via regulating the PI3K/Akt/NF-κB pathway through CypA/CD147, providing experimental evidence for elucidating the survival strategies of M. genitalium in host cells. KEY POINTS: • M. genitalium protein of adhesion inhibited human urethral epithelial cells apoptosis through CypA-CD147 activating the signal pathway of PI3K/Akt/NF-κB • The knockdown of CypA and CD147 could downregulate the M. genitalium -activated PI3K/Akt/NF-κB pathway in SV-HUC-1 cells • MgPa could inhibit the apoptosis of normal C57BL mouse primary urethral epithelial cells, but not for CypA-knockout C57BL mouse primary urethral epithelial cells.

The quorum sensing system of Novosphingobium sp. ERN07 regulates aggregate formation that promotes cyanobacterial growth.

Microbial aggregates play key roles in cyanobacterial blooms. Being a bacterial communication mechanism, quorum sensing (QS) synchronizes gene expression in a density-dependent manner and regulates bacterial physiological behavior. However, the regulatory role of QS in the formation of cyanobacteria-associated bacterial aggregates remains poorly understood. Here, we present insight into the role of QS in regulating bacterial aggregate formation in a representative bacterial strain, Novosphingobium sp. ERN07, which was isolated from Microcystis blooms in Lake Taihu. A biosensor assay showed that ERN07 exhibits significant AHL-producing capacity. Biochemical and microscopic analysis revealed that this strain possesses the ability to form aggregated communities. Gene knockout experiments indicated that the AHL-mediated QS system positively regulates bacterial aggregation. The aggregated communities possess the ability to enhance the production of extracellular polymeric substances (EPS), alter EPS composition ratios, and affect biofilm formation. The addition of aggregated substances also has a significant growth-promoting effect on M. aeruginosa. Transcriptomic analysis revealed that the aggregated substances positively regulate photosynthetic efficiency and energy metabolism of M. aeruginosa. These findings show that QS can mediate the aggregation phenotype and associated substrate spectrum composition, contributing to a better understanding of microalgal-bacterial interactions and mechanisms of Microcystis bloom maintenance in the natural environment.

Relation of cooked rice texture to starch structure and physicochemical properties under different nitrogen managements.

Nitrogen management, especially panicle nitrogen fertilization (PNF), can affect cooked rice textures by altering starch quality, but the details are unclear. In this study, the starch multi-level structures, physicochemical properties and cooked rice textures of indica under different nitrogen managements were analysed and their internal relations were investigated. With an increase in PNF, large granules, amylopectin short chains, amylose content, thermal temperatures, setback, and hardness first exhibited decreasing trends and then increasing trends, which were relatively lower under moderate PNF (N3), whereas α-1,6 linkage, relative crystallinity, protein content, enthalpy of gelatinization (△Hgel), peak viscosity, breakdown and stickiness exhibited the opposite trends. N3 treatment significantly increased △Hgel and breakdown and decreased setback, hardness and chewiness, suggesting that it might contribute to better starch thermal stability and pasting properties, ultimately improving cooked rice texture. Nitrogen management affected the texture of cooked rice mainly by improving starch multi-level structures, thermal and pasting viscosities.