Characterization of a novel antioxidant byssal protein from Mytilus coruscus foot.

Mussel byssal proteins are of biomimetic importance for the development of novel underwater bio-adhesive agents. It is important to maintain a reduced state during the process of byssus adhesion. There are 19 mussel foot proteins (MFPs) have been reported in previous studies, among which only MFP-6 had been confirmed as an antioxidant protein in mussel byssus due to the function of cysteines, and playing an essential role in the redox balance of mussel byssus during adhesion process. Although the other four MFPs (MFP-16 ~ MFP-19) also have abundant cysteines, their function is still unknown. In this study, a novel mussel foot protein, named MFP-20, was identified from Mytilus coruscus foot. The sequential features, expression profile, and function of recombinant MFP-20 were verified. The results showed that MFP-20 has more abundant cysteines than other MFPs, the relative expression of mfp-20 was upregulated in Fe3+ stress and low pH seawater. In addition, different adhesive substrates induced significant changes of expression level of mfp-20. Furthermore, rMFP-20 showed strong antioxidant capacity in the DPPH assay, and the abundant cysteines in its sequence may play vital roles in the antioxidation activity. Our findings revealed the possible function of MFP-20 with a totally different sequence from the reported MFP-6 and provided new clues for exploring the redox balance of mussel byssus during the adhesion process.

Primary diffuse large B-cell lymphoma of adrenal gland: A case report.

INTRODUCTION: Most adrenal tumors are benign and primary adrenal malignancies are relatively rare. Primary adrenal lymphoma (PAL) is a very rare and highly aggressive malignant tumor with unknown etiology, atypical clinical symptoms, nonspecific imaging manifestations, difficult disease diagnosis and poor prognosis. CASE REPORT: This case report details a 42-year-old woman who was admitted to the hospital with a 1-year-old bilateral adrenal mass and 1-month-old left upper abdominal pain. Enhanced CT of the abdomen showed a right adrenal nodule and a large occupying lesion in the left adrenal region, with a high probability of pheochromocytoma. Intraoperatively, a huge tumor measuring about 12*12*10 cm was found in the left adrenal region, infiltrating the left kidney, spleen and pancreatic tail. Postoperative pathology: lymphocytes were found in the renal capsule and subcapsule, lymphocytes were found in the pancreas; lymphocytes were found in the spleen. Consider a tumor of the lymphohematopoietic system, possibly lymphoma. CONCLUSION: This case demonstrates that primary adrenal diffuse large B-cell lymphoma (PADLBCL) is highly aggressive, has a poor prognosis, is prone to recurrence, has poor therapeutic outcomes, and is difficult to diagnose. Clinicians should consider the possibility of PADLBCL when encountering huge adrenal-occupying lesions and consider chemotherapy before surgery. Reducing the tumor size before surgery is a more favorable therapeutic approach, thus prolonging the patient life and improving the quality of survival.

Tranexamic Acid Ameliorates Skin Hyperpigmentation by Downregulating Endothelin-1 Expression in Dermal Microvascular Endothelial Cells.

BACKGROUND: Although reports suggest that tranexamic acid (TXA) has clinical benefits for melasma patients by oral, intralesional and topical treatment, the optimal route of TXA therapy and the underlying mechanism involved remain poorly defined. OBJECTIVE: To compare the skin lightening effect between oral TXA and topical TXA and to dissect the molecular mechanisms using ultraviolet B (UVB)-induced hyperpigmentation mouse model, ex vivo cultured human skin explant, and cultured melanocytes (MCs) and endothelial cells. METHODS: Melanin content and cluster of differentiation 31 (CD31)-positive cell numbers were measured in tail skins from UVB-irradiated mice treated by intragastral or topical TXA using immunofluorescent and Fontana-Masson staining. The conditioned medium (CM) was harvested from human umbilical vein endothelial cells treated with or without 3 mM TXA and was used to treat MCs for 48 hours. mRNA and protein levels of tyrosinase and microphthalmia-associated transcription factor were measured using quantitative real-time reverse transcription polymerase chain reaction and western blotting assays. HMB45- and CD31-positive cell numbers as well as melanin content were also examined in ex vivo cultured human skin explants. RESULTS: The hyperpigmented phenotype were significantly mitigated in UVB-irradiated tail skin plus intragastral TXA-treated mice compared with mice treated with UVB only or with UVB plus topical TXA. CD31-positive cell numbers correlated with the anti-melanogenic activity of TXA therapy. The data from cultured cells and skin tissues showed that suppression of endothelin-1 (ET-1) in vascular endothelial cells by TXA reduced melanogenesis and MC proliferation. CONCLUSION: Oral TXA outperforms topical TXA treatment in skin lightening, which contributes to suppression of ET-1 in dermal microvascular endothelial cells by TXA.

Enhancing intraneural revascularization following peripheral nerve injury through hypoxic Schwann-cell-derived exosomes: an insight into endothelial glycolysis.

BACKGROUND: Endothelial cell (EC)-driven intraneural revascularization (INRV) and Schwann cells-derived exosomes (SCs-Exos) both play crucial roles in peripheral nerve injury (PNI). However, the interplay between them remains unclear. We aimed to elucidate the effects and underlying mechanisms of SCs-Exos on INRV following PNI. RESULTS: We found that GW4869 inhibited INRV, as well as that normoxic SCs-Exos (N-SCs-Exos) exhibited significant pro-INRV effects in vivo and in vitro that were potentiated by hypoxic SCs-Exos (H-SCs-Exos). Upregulation of glycolysis emerged as a pivotal factor for INRV after PNI, as evidenced by the observation that 3PO administration, a glycolytic inhibitor, inhibited the INRV process in vivo and in vitro. H-SCs-Exos more significantly enhanced extracellular acidification rate/oxygen consumption rate ratio, lactate production, and glycolytic gene expression while simultaneously suppressing acetyl-CoA production and pyruvate dehydrogenase E1 subunit alpha (PDH-E1α) expression than N-SCs-Exos both in vivo and in vitro. Furthermore, we determined that H-SCs-Exos were more enriched with miR-21-5p than N-SCs-Exos. Knockdown of miR-21-5p significantly attenuated the pro-glycolysis and pro-INRV effects of H-SCs-Exos. Mechanistically, miR-21-5p orchestrated EC metabolism in favor of glycolysis by targeting von Hippel-Lindau/hypoxia-inducible factor-1α and PDH-E1α, thereby enhancing hypoxia-inducible factor-1α-mediated glycolysis and inhibiting PDH-E1α-mediated oxidative phosphorylation. CONCLUSION: This study unveiled a novel intrinsic mechanism of pro-INRV after PNI, providing a promising therapeutic target for post-injury peripheral nerve regeneration and repair.

Brunonianines D-F, three new C19-diterpenoid alkaloids from the Delphinium brunonianum, with therapeutic effect on ovarian cancer in vitro and in vivo.

The current standard treatment for ovarian cancer consists of surgery to reduce the size of the tumor, followed by treatment with chemotherapeutic drugs, which have major side effects. Therefore, finding a new natural product drug with fewer side effects is a strategy. Delphinium brunonianum (D. brunonianum) is a traditional Tibetan medicine, mainly from southern Tibet, China, whereas the chemical constituents in this plant remain elusive. The major metabolites in the dichloromethane fraction of D. brunonianum were analyzed and purified by HPLC and various column chromatography techniques. Nine diterpenoid alkaloids (1-9) and one amide alkaloid (10) were isolated from D. brunonianum, including three novel C19-type diterpenoid alkaloids (Brunonianines D-F) (1-3). Their structures were elucidated by 1D/2D NMR, HR-ESI-MS and single-crystal X-ray diffraction analyses. All compounds were evaluated for toxicity in four tumor cell lines. Most of the compounds exhibited potent inhibitory effects on Skov-3 cell lines, with IC50 values ranging from 2.57 to 8.05 µM. The western blotting experiment was used to further analyze the expression levels of molecules in the Bax/Bcl-2/Caspase-3 signaling pathway for compound 1. Molecular docking was performed to predict the binding modes of Brunonianine D with target proteins. In vivo experiments were also performed and evaluated in real time by monitoring the size of the Skov-3 tumor. Additionally, tumor H&E staining and the TUNEL assay used to evaluate anti-tumor effects.

Total Synthesis of Quebrachamine and Kopsiyunnanine D.

The total syntheses of (±)-quebrachamine and (±)-kopsiyunnanine D are reported. Key transformations include an intermolecular Horner-Wadsworth-Emmons olefination to merge the two fragments convergently and an intramolecular Mitsunobu reaction to introduce the synthetically challenging nine-membered azonane ring efficiently.

Construction of cyclobutane-fused tetracyclic skeletons via substrate-dependent EnT-enabled dearomative [2+2] cycloaddition of benzofurans (benzothiophenes)/maleimides.

Herein, a novel and facile organic photosensitizer (thioxanthone)-mediated energy-transfer-enabled (EnT-enabled) dearomative [2+2] cycloaddition of aromatic heterocycles/maleimides for green synthesis of cyclobutane-fused polycyclic skeletons is reported. Mechanistic investigations revealed that different EnT pathways by triplet thioxanthone were initiated when different aromatic heterocycles participated in the reaction, giving the corresponding excited intermediates, which underwent the subsequent intermolecular [2+2] cycloaddition to access the desired highly functionalized cyclobutane-fused polycyclic skeletons.

Chemical constituents of Rubia tibetica Hook. f. from Tibetan medicine and cytotoxic activity evaluation.

Two unprecedented quinone compounds Rubiaxylm A (1) and Rubiaxylm B (2), along with fifteen known anthraquinones (3-17) were isolated and characterized from the roots of Rubia tibetica in Tibetan medicine. Their structures were identified through comprehensive analyses of 1D/2D NMR as well as HR-ESIMS data. Furthermore, all separated compounds were evaluated for their cytotoxic activity on A549, Caco-2, MDA-MB-231 and Skov-3 cell lines. In particular, compound 2 effectively inhibited MDA-MB-231 cells with an IC50 value of 8.15 ± 0.20 µM. Subsequently, the anti-tumor mechanism of 2 was investigated by flow cytometry, JC-1 staining, cell scratching and cell colony. These results indicated that compound 2 could inhibit the proliferation of MDA-MB-231 cells by arresting cells in the G1 phase.

Histone derived antimicrobial peptides identified from Mytilus coruscus serum by peptidomics.

Histones and their N-terminal or C-terminal derived peptides have been studied in vertebrates and presented as potential antimicrobial agents playing important roles in the innate immune defenses. Although histones and their derived peptides had been reported as components of innate immunity in invertebrates, the knowledge about the histone derived antimicrobial peptides (HDAPs) in invertebrates are still limited. Using a peptidomic technique, a set of peptide fragments derived from the histones was identified in this study from the serum of microbes challenged Mytilus coruscus. Among the 85 identified histone-derived-peptides with high confidence, 5 HDAPs were chemically synthesized and the antimicrobial activities were verified, showing strong growth inhibition against Gram-positive bacteria, Gram-negative bacteria, and fungus. The gene expression level of the precursor histones matched by representative HDAPs were further tested using q-PCR, and the results showed a significant upregulation of the histone gene expression levels in hemocytes, gill, and mantle of the mussel after immune stress. In addition, three identified HDAPs were selected for preparation of specific antibodies, and the corresponding histones and their derived C-terminal fragments were detected by Western blotting in the blood cell and serum of immune challenged mussel, respectively, indicating the existence of HDAPs in M. coruscus. Our findings revealed the immune function of histones in Mytilus, and confirmed the existence of HDAPs in the mussel. The identified Mytilus HDAPs represent a new source of immune effector with antimicrobial function in the innate immune system, and thus provide promising candidates for the treatment of microbial infections in aquaculture and medicine.

Management of anastomotic biliary stricture through utilizing percutaneous transhepatic cholangioscopy.

AIM: Occurrence of anastomotic biliary stricture (AS) remains an essential issue following hepatobiliary surgeries, and percutaneous transhepatic cholangioscopy (PTCS) has great therapeutic significance in handling refractory AS for patients with altered gastrointestinal anatomy after cholangio-jejunostomy. This present study aimed to investigate feasibility of PTCS procedures in AS patients for therapeutic indications. MATERIALS AND METHODS: This study was a single-center, retrospective cohort study with a total number of 124 consecutive patients who received therapeutic PTCS due to AS. Clinical success rate, required number, and adverse events of therapeutic PTCS procedures as well as patients survival state were reviewed. RESULTS: These 124 patients previously underwent choledochojejunostomy or hepatico-jejunostomy, and there was post-surgical altered gastrointestinal anatomy. Overall, 366 therapeutic PTCS procedures were performed for these patients through applying rigid choledochoscope, and the median time of PTCS procedures was 3 (1-11). Among these patients, there were 34 cases (27.32%) accompanied by biliary strictures and 100 cases (80.65%) were also combined with biliary calculi. After therapeutic PTCS, most patients presented with relieved clinical manifestations and improved liver functions. The median time of follow-up was 26 months (2-86 months), and AS was successfully managed through PTCS procedures in 104 patients (83.87%). During the follow-up period, adverse events occurred in 81 cases (65.32%), most of which were tackled through supportive treatment. CONCLUSION: PTCS was a feasible, safe and effective therapeutic modality for refractory AS, which may be a promising alternative approach in clinical cases where the gastrointestinal anatomy was changed after cholangio-jejunostomy.

Revision of the rare Buprestis subgenus Akiyamaia Kurosawa, 1988 (Coleoptera: Buprestidae: Buprestinae), with description of two new species.

In this paper, two new species of Buprestis subgenus Akiyamaia Kurosawa, 1988 are described: B. (A.) gengmini Qi & Song, new species from Yunnan Province, China and B. (A.) wenii Qi & Song, new species from Yen Bai Province, Vietnam. The descriptions and illustrations of two new species are provided, and the diagnostic characters are provided to distinguish the two new species from other related species. A key is given for identification of all Akiyamaia species.The holotype of B. (A.) costipennis (Fairmaire, 1891) and pictures of living individuals are illustrated for the first time.

New records of Chrysochroinae Laporte de Castelnau, 1835 (Coleoptera, Buprestidae) from China.

Background: Chrysochroinae Laporte de Castelnau, 1835 is the very colourful subfamily of Buprestidae. There are 127 species and subspecies of the subfamily which have been recorded in China. New information: In this paper, we reported three genera, two subgenera and five species of the subfamily Chrysochroinae Laporte de Castelnau, 1835 (Coleoptera, Buprestidae) which are all newly recorded from China. These reported taxa belong to two tribes and four genera: Chrysochroa (Chroodema) corbetti (Kerremans, 1893), Chrysochroa (Pyranthe) fulgens ephippigera White, 1843, Demochroa (Demoxantha) gratiosa indica Csiki, 1900, Xanthocatabonvouloirii (Deyrolle, 1861) (all the above four being Chrysochroini) and Cardiaspismouhotii E. Saunders, 1866 (Dicercini). The five newly-recorded species are briefly described, illustrated and supplemented with relevant biological information.

Association between obstructive sleep apnea and low bone mass in adults: a systematic review and meta-analysis.

Introduction: This study aimed to synthesize existing evidence on the potential association between obstructive sleep apnea (OSA) and low bone mass in adults. Methods: Electronic searches of four main databases were performed. The inclusion criteria consisted of observational studies investigating the relationship between OSA and bone mass, osteoporosis, fractures, or bone metabolism markers in adult population. Bone mineral density (BMD) and T score of lumbar and femur neck, incidence of osteoporosis and fractures, bone metabolism marker levels were extracted as primary outcomes. Results: Among the 693 relevant publications, 10 studies consisting of 158,427 participants met with the inclusion and exclusion criteria. Meta-analysis showed a significant lower BMD of lumbar (mean difference (MD) = - 0.03; 95% CI - 0.05, - 0.01; I2 = 46%), femur neck (MD = - 0.06; 95% CI - 0.12, 0.00; I2 = 71%), and a significant lower T score of lumbar (MD = - 0.42; 95% CI - 0.79, - 0.05; I2 = 63%) in the OSA group. The results suggested that both male (odds ratio (OR) = 2.03; 95% CI 1.23, 3.35; I2 = 38%) and female (OR = 2.56; 95% CI 1.96, 3.34; I2 = 0%) had higher risk of osteoporosis in the OSA group. Besides, meta-analysis also showed that bone-specific alkaline phosphatase was significantly lower in OSA patients (MD = - 1.90; 95% CI - 3.48, - 0.32; I2 = 48%). Conclusions: A potential association between OSA and lower bone mass in adults is preliminarily proved. It also seems plausible that both male and female with OSA have a higher risk of osteoporosis. Supplementary Information: The online version contains supplementary material available at 10.1007/s41105-023-00481-1.

The Research Trend of Soft Tissue Filler Injection from 2000 to 2022: A Bibliometric and Visualized Analysis.

Background: The demand for soft tissue filler injections has experienced a significant increase in recent years. Therefore, this study used bibliometric analysis to identify prominent research areas and emerging trends within the field. Methods: Publications concerning research on soft tissue filler injections were collected from the Web of Science Core Collection database. Subsequently, VOSviewer 1.6.18 and CiteSpace 6.2.R4 software were used to analyze the co-authorship, co-occurrence, and citations of countries, institutions, authors, hotspot keywords, and journals associated with these studies. Results: A total of 1370 records pertaining to filler injection research conducted between 2000 and 2022 were identified. The United States (524 publications) emerged as the country with the highest number of publications in this field, with Mayo Clinic (37 publications) making the most substantial contribution. Dermatologic Surgery emerged as the leading journal in this field, publishing the highest number of research articles (151 publications) and also being the most frequently co-cited. Cotofana proved to be the most prolific author with 51 publications, and Lemperle emerged as the most frequently co-cited author with 628 citations (including total link strength: 6587). The most popular keywords, in descending order of popularity, were "dermal filler," "injection," "soft-tissue augmentation," "complications," and "hyaluronic acid." Conclusions: The findings of this study offer a comprehensive overview of the main directions in filler injection research. Furthermore, they underscore the imperative of intensifying efforts to prevent complications linked to filler injections.

Photomediated Hydro(deutero)acylation of Olefins by Decarboxylative Addition of α-Oxocarboxylic Acids.

Acyl radicals have been generated from the decarboxylation of α-oxocarboxylic acids by using a readily accessible organic pyrimidopteridine photoredox catalyst under ultraviolet-A (UV-A) light irradiation. These reactive acyl radicals were smoothly added to olefins such as styrenes and diverse Michael acceptors, with the assistance of H2O/D2O as hydrogen donors, enabling easy access to a diverse range of ketones/ß-deuterio ketones. A wide range of α-oxocarboxylic acids are compatible with this reaction, which shows a reliable, atom-economical, and eco-friendly protocol. Furthermore, postsynthetic diversifications and applications are presented.

Concurrent chemoradiotherapy versus radiotherapy alone in older patients with stage II nasopharyngeal carcinoma after intensity-modulated radiotherapy: A propensity score-matched cohort study.

BACKGROUND AND PURPOSE: Whether concurrent chemoradiotherapy (CCRT) benefits the older (age ≥ 60 years) patients with stage II nasopharyngeal carcinoma (NPC) has not been determined. This study aimed to compare the outcomes and toxicities of CCRT with Intensity-Modulated Radiotherapy (IMRT) alone in older patients with stage II NPC. MATERIALS AND METHODS: Between January 2010 and December 2017, 220 older (age ≥ 60 years) patients with stage II NPC were analyzed. A pair of 53 patients were matched between the CCRT group and RT group by using propensity score matching (PSM) in terms of age, sex, pathological type, T and N stage, ACE-27 scores, CRP, LDH and Hb. Cancer-specific survival (CSS), progression-free survival (PFS), locoregional relapse-free survival (LRRFS) and distant metastasis-free survival (DMFS) were analysed by the Kaplan-Meier method and log-rank test. Multivariate analysis was performed to assess the prognostic risk factors by using a Cox's proportional hazards regression model. Treatment toxicities were clarified and compared between the two groups by using the χ2 test. RESULTS: The median follow-up time of the whole cohort was 82.0 months (range, 11-151 months). PSM analysis indicated that compared with the RT group, significantly higher 5-year CSS (98.1 % vs. 83.0 %, P = 0.02), PFS (98.1 % vs. 79.2 %, P = 0.01) and DMFS (100.0 % vs. 92.4 %, P = 0.04) were observed in the CCRT group. Multivariate analysis showed that CCRT was an independent prognostic factor predicting CSS (HR, 0.34; 95 % CI, 0.15-0.79; P = 0.01), PFS (HR, 0.48; 95 % CI, 0.25-0.93; P = 0.03), and LRRFS (HR, 0.36; 95 % CI, 0.14-0.90; P = 0.03), and a higher ACE-27 score predicted a worse CSS. Patients in the CCRT group experienced higher frequencies of the acute toxicities than patients in the RT group. Late complications were comparable between the two groups. CONCLUSION: CCRT significantly improved the survival benefits for the older patients with stage II NPC compared with IMRT alone without adding late complications, whereas increased some of the treatment-associated acute toxicities.

Brunonianines A-C, C20-diterpenoid alkaloids with cyano group from Delphinium brunonianum Royle.

Cyano tends to have better biological activity, but it is rarely reported in natural products, especially in the C20-diterpene alkaloids. Herein, three unprecedented C20-diterpenoid alkaloids, brunonianines A-C (1-3), possessing rare cyano functional group as well as an atisine backbone constructed from a phenethyl substituent and a tetrahydropyran ring, along with four C19-alkaloids (4-7) and one amide alkaloids (8), were isolated from the whole plant of Delphinium brunonianum Royle. Compounds 1-3 are also the first atisine type diterpenoid alkaloids with cyano group obtained from nature. The structures of the previously undescribed compounds were elucidated by HR-ESI-MS, 1D/2D NMR spectroscopic data and electronic circular dichroism calculations and single-crystal X-ray diffraction. Reasonable speculations have also been made regarding the biogenic synthetic pathways of compounds 1-3. In addition, the inhibitory activity of all compounds was also tested against four tumor lines: A549, Caco-2, H460 and Skov-3, where compound 2 (IC50 2.20 ± 0.21 µM) showed better inhibitory activity against Skov-3 cells than the hydroxycamptothecin. Using flow cytometry, cell staining, migration and invasion analysis, and Western blot, compound 2 was found to arrest cells in the G2/M phase and was able to effectively inhibit cell motility to achieve potent anti-tumor effects. In addition, compound 2 can effectively induce apoptosis by activating the Bax/Bcl-2/Caspase-3 signaling pathway.

Pathways of Media Contact to Health Literacy in Middle-Aged and Older People: The Chain Mediation Effect of Perceived Social Support and Self-Efficacy.

Objective: To understand the status of media exposure, social support, self-efficacy, and health literacy among middle-aged and older adults in China, and explore the impact path of media exposure on the health literacy of this population, providing a reference for promoting their physical and mental health. Methods: From July to November 2022, a multi-stage random sampling method was employed to survey 16,938 Chinese middle-aged and older adults aged 46 and above. Structural equation modeling and statistical analysis were conducted using LISREL 8.8 and Mplus 8.3 software. Results: The average score for media exposure among Chinese middle-aged and older adults was (18.55±5.36), perceived social support was (60.68±12.51), self-efficacy was (28.76±5.40), and health literacy was (35.49±6.05). Statistical results revealed that media exposure has a positive impact on the health literacy of middle-aged and older adults, with a direct effect of 0.091 (p < 0.001). Mediation analysis showed that media exposure can affect the health literacy of this population through the independent mediating effects of perceived social support (ß = 0.013, p < 0.001) and self-efficacy (ß = 0.029, p < 0.001), as well as through a chain mediation effect involving perceived social support and self-efficacy (ß = 0.015, p < 0.001). Conclusion: As a pathway for health information dissemination, media exposure plays a crucial role in the intervention of health literacy among middle-aged and older adults. Perceived social support and self-efficacy not only have independent mediating effects but also significant chain mediating effects in the relationship between media exposure and health literacy among this population. Therefore, improving the health literacy of middle-aged and older people can be popularized through media and improved in a multi-path, all-round, and precise way with the help of related technologies and social forces from which media literacy can be improved.

The molecular response of Mytilus coruscus mantle to shell damage under acute acidified sea water revealed by iTRAQ based quantitative proteomic analysis.

Mytilus coruscus is an economically important marine bivalve that lives in estuarine sea areas with seasonal coastal acidification and frequently suffers shell injury in the natural environment. However, the molecular responses and biochemical properties of Mytilus under these conditions are not fully understood. In the present study, we employed tandem mass spectrometry combined with isobaric tagging to identify differentially expressed proteins in the mantle tissue of M. coruscus under different short-term treatments, including shell-complete mussels raised in normal seawater (pH 8.1), shell-damaged mussels raised in normal seawater (pH 8.1), and acidified seawater (pH 7.4). A total of 2694 proteins were identified in the mantle, and analysis of their relative abundance from the three different treatments revealed alterations in the proteins involved in immune regulation, oxidation-reduction processes, protein folding and processing, energy provision, and cytoskeleton. The results obtained by quantitative proteomic analysis of the mantle allowed us to delineate the molecular strategies adopted by M. coruscus in the shell repair process in acidified environments, including an increase in proteins involved in oxidation-reduction processes, protein processing, and cell growth at the expense of proteins involved in immune capacity and energy metabolism. SIGNIFICANCE: The impact of global ocean acidification on calcifying organisms has become a major ecological and environmental problem in the world. Mytilus coruscus is an economically important marine bivalve living in estuary sea area with seasonal coastal acidification, and frequently suffering shell injury in natural environment. Molecular responses of M coruscus under the shell damage and acute acidification is still largely unknown. For this reason, iTRAQ based quantitative proteomic and histological analysis of the mantle from M. coruscus under shell damage and acute acidification were performed, for revealing the proteomic response and possible adaptation mechanism of Mytilus under combined shell damage and acidified sea water, and understanding how the mussel mantle implement a shell-repair process under acidified sea water. Our study provides important data for understanding the shell repair process and proteomic response of Mytilus under ocean acidification, and providing insights into potential adaptation of mussels to future global change.

The Functional Significance of McMafF_G_K in Molluscs: Implications for Nrf2-Mediated Oxidative Stress Response.

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a pivotal regulator of antioxidant gene expression in mammals, forming heterodimer complexes with small Maf proteins through its BZip domain. However, the underlying mechanism of Nrf2 action in molluscs remains poorly understood. The thick shell mussel, Mytilus coruscus, represents a model organism for the marine environment and molluscs interaction research. In this study, we used in silico cloning to obtain a small Maf homologue called McMafF_G_K from M. coruscus. McMafF_G_K possesses a typical BZip domain, suggesting its affiliation with the traditional small Maf family and its potential involvement in the Nrf2 signaling pathway. Transcriptional analysis revealed that McMafF_G_K exhibited a robust response to benzo[a]pyrene (Bap) in the digestive glands. However, this response was down-regulated upon interference with McMafF_G_K-siRNA. Interestingly, the expression levels of Nrf2, NAD(P)H: quinone oxidoreductase (NQO-1), and Glutathione Peroxidase (GPx), which are key players in oxidative stress response, showed a positive correlation with McMafF_G_K in digested adenocytes of M. coruscus. Furthermore, in vitro analysis of antioxidant capacity in digestive gland cells demonstrated that Bap exposure led to an increase in reactive oxygen species (ROS) levels, accompanied by an elevation in total antioxidant capacity (T-AOC), potentially counterbalancing the excessive ROS. Strikingly, transfection of McMafF_G_K siRNA resulted in a significant rise in ROS level and a down-regulation of T-AOC level. To validate the functional relevance of McMafF_G_K, a glutathione S-transferase (GST) pull-down assay confirmed its interaction with McNrf2, providing compelling evidence of their protein interaction. This study significantly contributes to our understanding of the functional role of McMafF_G_K in the Nrf2 signaling pathway and sheds light on its potential as a target for further research in oxidative stress response.