Stratification of dissolved organic matter in the upper 5000 m water column in the western Pacific Ocean.

Marine dissolved organic matter (DOM) is a principal reservoir involved in biogeochemical cycles and exerts a pivotal influence on global carbon flux dynamics. In this study, excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis (EEM-PARAFAC) was conducted on 230 DOM samples collected from 21 sites between February and April 2022 in the Western Pacific Ocean (WPO). We identified five distinct fluorescence peaks (peaks B, T, A, C, and M), predominantly protein-like and humic-like components. These findings, marked by significant differences (p < 0.01) in fluorescence intensities and spectral indices, characterized the transformation of DOM with ocean depth, illustrating a transition from active to recalcitrant forms. Additionally, random forest analysis (RFA) identified depth as a key factor influencing marine dissolved organic carbon (DOC), with a 32.59% importance value. Correlations between hydrological and fluorescent parameters underscored the complexity of DOM sources and influencing processes. Overall, this work broadens our understanding of DOM variability in the upper 5000 m of the WPO, enhancing our knowledge of the marine environment's role in the global carbon cycle.

Mesenchymal stem cells and dental implant osseointegration during aging: from mechanisms to therapy.

Dental implants are widely used to replace missing teeth, providing patients with unparalleled levels of effectiveness, convenience, and affordability. The biological basis for the clinical success of dental implants is osseointegration. Bone aging is a high-risk factor for the reduced osseointegration and survival rates of dental implants. In aged individuals, mesenchymal stem cells (MSCs) in the bone marrow show imbalanced differentiation with a reduction in osteogenesis and an increase in adipogenesis. This leads to impaired osseointegration and implant failure. This review focuses on the molecular mechanisms underlying the dysfunctional differentiation of aged MSCs, which primarily include autophagy, transcription factors, extracellular vesicle secretion, signaling pathways, epigenetic modifications, microRNAs, and oxidative stress. Furthermore, this review addresses the pathological changes in MSCs that affect osseointegration and discusses potential therapeutic interventions to enhance osseointegration by manipulating the mechanisms underlying MSC aging.

IRAK4 inhibition: an effective strategy for immunomodulating peri-implant osseointegration via reciprocally-shifted polarization in the monocyte-macrophage lineage cells.

BACKGROUND: The biomaterial integration depends on its interaction with the host immune system. Monocyte-macrophage lineage cells are immediately recruited to the implant site, polarized into different phenotypes, and fused into multinucleated cells, thus playing roles in tissue regeneration. IL-1R-associated kinase 4 (IRAK4) inhibition was reported to antagonize inflammatory osteolysis and regulate osteoclasts and foreign body giant cells (FBGCs), which may be a potential target in implant osseointegration. METHODS: In in-vitro experiments, we established simulated physiological and inflammatory circumstances in which bone-marrow-derived macrophages were cultured on sand-blasted and acid-etched (SLA) titanium surfaces to evaluate the induced macrophage polarization, multinucleated cells formation, and biological behaviors in the presence or absence of IRAK4i. Then, bone marrow stromal stem cells (BMSCs) were cultured in the conditioned media collected from the aforementioned induced osteoclasts or FBGCs cultures to clarify the indirect coupling effect of multinucleated cells on BMSCs. We further established a rat implantation model, which integrates IRAK4i treatment with implant placement, to verify the positive effect of IRAK4 inhibition on the macrophage polarization, osteoclast differentiation, and ultimately the early peri-implant osseointegration in vivo. RESULTS: Under inflammatory conditions, by transforming the monocyte-macrophage lineage cells from M1 to M2, IRAK4i treatment could down-regulate the formation and activity of osteoclast and relieve the inhibition of FBGC generation, thus promoting osteogenic differentiation in BMSCs and improve the osseointegration. CONCLUSION: This study may improve our understanding of the function of multinucleated cells and offer IRAK4i as a therapeutic strategy to improve early implant osseointegration and help to eliminate the initial implant failure.

Pto Interaction Proteins: Critical Regulators in Plant Development and Stress Response.

Pto interaction (Pti) proteins are a group of proteins that can be phosphorylated by serine/threonine protein kinase Pto, which have diverse functions in plant development and stress response. In this study, we analyzed the phylogenetic relationship, gene structure, and conserved motifs of Pti1s and predicted the potential cis-elements in the promoters of Pti1 genes using bioinformatics methods. Importantly, we systematically summarized the diverse functions of Pti1s in tomato, rice, Arabidopsis, potato, apple, and cucumber. The potential cis-elements in promoters of Pti1s decide their functional diversity in response to various biotic and abiotic stresses. The protein kinase Pti1 was phosphorylated by Pto and then modulated the downstream signaling pathways for PTI and ETI in the disease insistence process. In addition, some transcription factors have been defined as Ptis (e.g., Pti4, Pti5, and Pti6) originally, which actually were ethylene-response factors (ERFs). Pti4, Pti5, and Pti6 were modulated by salicylic acid (SA), jasmonate (JA), and ethylene signaling pathways and regulated diverse defense-related gene expression to cope with Pst infection and insect wounding.

Sinking Rate and Community Structures of Autumn Phytoplankton Responses to Mesoscale Physical Processes in the Western South China Sea.

To examine the influence of mesoscale eddy on the natural phytoplankton community and its sinking rate changes, a comprehensive investigation cruise was carried out in the western South China Sea in autumn 2016. A total of 108 phytoplankton species were found, which belong to 54 phytoplankton genera; most of them were dominated by Dinophyta (54 genera), followed by Bacillariophyta (50 genera), Cyanophyta (3 genera), and Chrysophyta (1 genus). Bacillariophyta and Dinophyta were the main phytoplankton communities in the investigated sea area. The sinking rate of phytoplankton ranged from 0.12 to 3.17 m day-1, determined by the SETCOL method. The highest phytoplankton sinking rate was found in the 200-m water layer, followed by the DCM layer. No significant correlation was found between phytoplankton sinking rates and most of the environmental parameters during this cruise. At a similar time, we have carried out the estimation of carbon flux in the investigated sea area by using the sinking rate of phytoplankton, which showed that the carbon flux ranged from 2.41 × 10-6 to 0.006 mg C m-2 day-1; in addition, the maximum was at the 200-m layer. Phytoplankton community and sinking rate were significantly affected by the mesoscale eddy processes. The cold eddy could affect the community distribution of diatom and dinoflagellate, and the upwelling mainly affects the community of dinoflagellate. Both of them could contribute to a higher sedimentation rate of phytoplankton in the surface and DCM layers. Warm eddy could reduce the abundance of phytoplankton in the surface layer; simultaneously, the sinking rate of phytoplankton in the shallow water layer above 100 m is also reduced. These results can fill in the knowledge gap of mesoscale eddy processes in the study of phytoplankton community change and sinking rate; furthermore, it can provide insights into phytoplankton carbon and its implementation in further carbon sink.

[Construction of Dishevelled 2-targeted siRNA vectors and identification of the effective recombinant plasmids].

OBJECTIVE: To construct Dishevelled 2 (Dvl2)-targeted siRNA plasmids and to identify the effective recombinant plasmids in transciently-transfected RAW264.7 cells. METHODS: The interfering sequences of Dvl2 were designed according to the sequence of Dvl2 of GenBank. Five paires of oligonucleotides were synthesized and inserted into plasmid pMAGic 4.0 to generate siRNA expression vectors, which were identified by flora PCR and sequence analysis. The recombinant plasmids siRNA-Dvl2 was transciently transfected into RAW264.7 cells by Lipofectamine 2000, which was confirmed under a fluorescence microscope and the interfering efficiency was detected by real-time RT-PCR. RESULTS: Five Dvl2 siRNA frames were successfully inserted into the plasmid vector pMAGic 4.0, and the flora PCR and sequence analysis confirmed the correct construction. Three of the five siRNA vectors suppressed the expression of Dvl2 mRNA, in which the siRNA-Dvl2-3 was the most efficient. CONCLUSION: The Dvl2-targeted recombinant siRNA plasmids can be constructed successfully to inhibit Dvl2 mRNA expression in transciently-transfected RAW264.7 cells, which can be used to pack virus particles and to construct siRNA-Dvl2 stably-transfected RAW264.7 cells in further research.

[Construction of vectors encoding mouse Dishevelled 2 and its expression in RAW264.7 cells].

OBJECTIVE: To construct the recombinant vectors that express mouse Dishevelled 2 (Dvl2), and to evaluate its expression level in transfected RAW264.7 cells. METHODS: A pair of specific primers were designed according to the mouse Dvl2 cDNA sequence published in GenBank. Total RNA of RAW264.7 cells was extracted, and open reading frame of Dvl2 was obtained by RT-PCR, which was then cloned into pEZ-M29 plasmid. Electrophoresis after macrorestriction and DNA sequence analysis were used to identify the reconstructed plasmids. After transient transfection via liposome, the transfection of RAW264.7 cells was confirmed under a fluorescence microscope, and the expression level of Dvl2 was evaluated by real-time RT-PCR. RESULTS: The recombinant plasmid containing mouse Dvl2, namely pEZ-M29/ Dvl2, was successfully constructed, and confirmed by DNA sequence analysis. After 48 h of tranfection, the expression of enhanced green fluorescene protein was observed under a fluorescence microscope, and real-time RT-PCR analysis revealed that the Dvl2 mRNA level was prominantly elevated in the transient transfected RAW264.7 cells. CONCLUSION: The recombinant plasmids pEZ-M29/Dvl2 are successfully constructed and can elevate the Dvl2 mRNA level in the transient transfected RAW264.7 cells, which can be used in further studies aiming at revealing the functional significance of Dvl2 in the osteoclastogenesis.

Preliminary identification of potential PDZ-domain proteins downstream of ephrin B2 during osteoclast differentiation of RAW264.7 cells.

The EphB4 receptor and ephrin B2 ligand were recently reported to influence the coupling between osteoclasts and osteoblasts in bone biology, but their downstream signaling pathways remain unclear. This study focuses on the preliminary identification of downstream PDZ-domain proteins involved in EphB4/ephrin B2 reverse signaling in osteoclasts. Similarly to primary osteoclast precursors isolated from the bone, we observed that the RAW264.7 cell line, a mouse monocyte/macrophage cell line that is used in conventional assays for osteoclast function, expressed ephrin B2 during RANKL-induced osteoclast differentiation, and that preclustered EphB4 inhibited this osteoclast differentiation. The results demonstrate that RAW264.7 cells provide a good model for further research of EphB4/ephrin B2 signaling in osteoclasts. Immunofluorescence staining and Western blot analysis revealed that all of the eight PDZ-domain proteins previously reported to interact with ephrin B ligands were expressed in the differentiated RAW264.7 osteoclasts. However, in a co-immunoprecipitation assay, only Dishevelled 2 (Dvl2) among eight PDZ-domain proteins tested co-precipitated with ephrin B2 and vice versa, suggesting an endogenous interaction between Dvl2 and ephrin B2 in RANKL-induced osteoclasts. Furthermore, preclustered EphB4 reduced the expression level of Dvl2. Collectively, our results indicate that Dvl2 could be the potential PDZ-domain protein that acts downstream of ephrin B2 in RANKL-induced osteoclast differentiation of RAW264.7 cells, providing a potential novel therapeutic target for bone diseases.

[Effect of aurum coating on corrosion resistance of Ni-Cr alloy].

OBJECTIVE: To evaluate the effect of aurum coating on corrosion resistance of Ni-Cr alloy in artificial saliva environment. METHODS: The corrosion potential (E(corr)), self-corrosion current density (I(corr)), and polarization resistance (R(p)) of three alloys were measured using electrochemical methods to compare the difference of corrosion resistance between aurum-coated Ni-Cr alloy and Ni-Cr alloy or Au alloy. Meanwhile, microstructural and phase diffraction was examined with field scanning electromicroscopy (FSEM) and surface chemical analysis was performed by energy diffraction X-ray (EDX). RESULTS: The I(corr) of aurum-coated Ni-Cr alloy was (0.70 +/- 0.20) x 10(-6) A/cm2, which was significantly higher than that of Au alloy (P < 0.05) and lower than that of Ni-Cr alloy (P < 0.05). R(p) of aurum-coated Ni-Cr alloy was (34.77 +/- 12.61) KOmega.cm2, which was higher than that of Ni-Cr alloy (P < 0.05) and lower than that of Au alloy (P < 0.05). The results of FSEM showed that the corrosion resistance of Ni-Cr alloy coated with aurum was better than that of Ni-Cr alloy. The results of EDX indicated that released Ni and Cr of Ni-Cr alloy coated with aurum after test were less than those of Ni-Cr alloy (P < 0.05). CONCLUSIONS: The corrosion resistance of aurum-coated Ni-Cr alloy is higher than that of Ni-Cr alloy.