Depressed 660-km discontinuity caused by akimotoite-bridgmanite transition.

The 660-kilometre seismic discontinuity is the boundary between the Earth's lower mantle and transition zone and is commonly interpreted as being due to the dissociation of ringwoodite to bridgmanite plus ferropericlase (post-spinel transition)1-3. A distinct feature of the 660-kilometre discontinuity is its depression to 750 kilometres beneath subduction zones4-10. However, in situ X-ray diffraction studies using multi-anvil techniques have demonstrated negative but gentle Clapeyron slopes (that is,  the ratio between pressure and temperature changes) of the post-spinel transition that do not allow a significant depression11-13. On the other hand, conventional high-pressure experiments face difficulties in accurate phase identification due to inevitable pressure changes during heating and the persistent presence of metastable phases1,3. Here we determine the post-spinel and akimotoite-bridgmanite transition boundaries by multi-anvil experiments using in situ X-ray diffraction, with the boundaries strictly based on the definition of phase equilibrium. The post-spinel boundary has almost no temperature dependence, whereas the akimotoite-bridgmanite transition has a very steep negative boundary slope at temperatures lower than ambient mantle geotherms. The large depressions of the 660-kilometre discontinuity in cold subduction zones are thus interpreted as the akimotoite-bridgmanite transition. The steep negative boundary of the akimotoite-bridgmanite transition will cause slab stagnation (a stalling of the slab's descent) due to significant upward buoyancy14,15.

Small RNAs >26 nt in length associate with AGO1 and are upregulated by nutrient deprivation in the alga Chlamydomonas.

Small RNAs (sRNAs) associate with ARGONAUTE (AGO) proteins forming effector complexes with key roles in gene regulation and defense responses against molecular parasites. In multicellular eukaryotes, extensive duplication and diversification of RNA interference (RNAi) components have resulted in intricate pathways for epigenetic control of gene expression. The unicellular alga Chlamydomonas reinhardtii also has a complex RNAi machinery, including 3 AGOs and 3 DICER-like proteins. However, little is known about the biogenesis and function of most endogenous sRNAs. We demonstrate here that Chlamydomonas contains uncommonly long (>26 nt) sRNAs that associate preferentially with AGO1. Somewhat reminiscent of animal PIWI-interacting RNAs, these >26 nt sRNAs are derived from moderately repetitive genomic clusters and their biogenesis is DICER-independent. Interestingly, the sequences generating these >26-nt sRNAs have been conserved and amplified in several Chlamydomonas species. Moreover, expression of these longer sRNAs increases substantially under nitrogen or sulfur deprivation, concurrently with the downregulation of predicted target transcripts. We hypothesize that the transposon-like sequences from which >26-nt sRNAs are produced might have been ancestrally targeted for silencing by the RNAi machinery but, during evolution, certain sRNAs might have fortuitously acquired endogenous target genes and become integrated into gene regulatory networks.

Mosaic RBD nanoparticles induce intergenus cross-reactive antibodies and protect against SARS-CoV-2 challenge.

Recurrent spillovers of α- and ß-coronaviruses (CoV) such as severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome-CoV, SARS-CoV-2, and possibly human CoV have caused serious morbidity and mortality worldwide. In this study, six receptor-binding domains (RBDs) derived from α- and ß-CoV that are considered to have originated from animals and cross-infected humans were linked to a heterotrimeric scaffold, proliferating cell nuclear antigen (PCNA) subunits, PCNA1, PCNA2, and PCNA3. They assemble to create a stable mosaic multivalent nanoparticle, 6RBD-np, displaying a ring-shaped disk with six protruding antigens, like jewels in a crown. Prime-boost immunizations with 6RBD-np in mice induced significantly high Ab titers against RBD antigens derived from α- and ß-CoV and increased interferon (IFN-γ) production, with full protection against the SARS-CoV-2 wild type and Delta challenges. The mosaic 6RBD-np has the potential to induce intergenus cross-reactivity and to be developed as a pan-CoV vaccine against future CoV spillovers.

Thermal Equation of State of Cubic Silicon Carbide at High Pressures.

We have performed in situ X-ray diffraction measurements of cubic silicon carbide (SiC) with a zinc-blende crystal structure (B3) at high pressures and temperatures using multi-anvil apparatus. The ambient volume inferred from the compression curves is smaller than that of the starting material. Using the 3rd-order Birch-Murnaghan equation of state and the Mie-Grüneisen-Debye model, we have determined the thermoelastic parameters of the B3-SiC to be K0=228±3 GPa, K0',=4.4±0.4, q=0.27±0.37, where K0, K0' and q are the isothermal bulk modulus, its pressure derivative and logarithmic volume dependence of the Grüneisen parameter, respectively. Using the 3rd-order Birch-Murnaghan EOS with the thermal expansion coefficient, the thermoelastic parameters have been found as K0=221±3 GPa, K0',=5.2±0.4, α0=0.90±0.02 ⋅ 10-5 ⋅ K-1, where α0 is the thermal expansion coefficient at room pressure and temperature. We have determined that paired B3-SiC - MgO calibrants can be used to estimate pressure and temperature simultaneously in ultrahigh-pressure experiments up to 60 GPa.

Efficacy of immune-checkpoint inhibitors combined with cytotoxic chemotherapy in advanced or recurrent endometrial cancer: A systematic review and meta-analysis.

BACKGROUND: The combination of immune checkpoint inhibitors (ICIs) and platinum-based chemotherapy has emerged as a highly promising primary option for advanced or recurrent endometrial cancer (EC). The study aimed to evaluate treatment efficacy of ICIs with cytotoxic chemotherapy in EC. METHODS: We conducted a comprehensive review of randomized controlled trials up to November 11, 2023, focusing on immunotherapy combined with chemotherapy versus chemotherapy alone for EC. The primary endpoint was the pooled hazard ratio (HR), which was further analyzed across subgroups based on mismatch repair (MMR) status, race, histology, and programmed death-ligand 1 (PD-L1) status. The protocol was registered in PROSPERO (CRD42023475669). FINDINGS: Four trials with 2335 patients were analyzed. ICIs with chemotherapy significantly prolonged progression-free survival (PFS) (HR, 0.70; 95% CI, 0.62-0.79) and overall survival (OS) (HR, 0.75; 95% CI, 0.63-0.89) compared to chemotherapy alone. Stratification by MMR status showed substantial benefits for dMMR (PFS; HR, 0.33; 95% CI, 0.26-0.43; OS; HR, 0.37; 95% CI, 0.22-0.91) over pMMR cohorts in both PFS and OS. In the subgroup analysis, there was significant PFS advantage in Caucasian (HR, 0.63; 95% CI, 0.54-0.72) over non-Caucasian, in endometrioid histology (HR, 0.66; 95% CI, 0.56-0.78) over non-endometrioid, and in PD-L1 positive (HR, 0.39; 95% CI, 0.19-0.81) over PD-L1 negative population. INTERPRETATION: ICIs combined with platinum-based chemotherapy significantly prolonged PFS and OS in patients with advanced or recurrent EC. Patients with dMMR status, Caucasians, endometrioid histology, and positive PD-L1 status showed significant PFS benefits, emphasizing the need for personalized treatment approaches to improve outcomes.

Transcriptome and functional analyses of phenotypic plasticity in sea grape Caulerpa okamurae.

Caulerpa is a marine green macroalga distinguished by a large single cell with multiple nuclei. It also exhibits remarkable morphological intraspecies variations, in response to diverse environmental types. However, the molecular mechanisms underlying this phenotypic plasticity remain poorly understood. In this work, we compare the transcriptomes of Caulerpa okamurae Weber Bosse, 1897 displaying altered phenotypes of cultivation and natural phenotypes and investigate significantly regulated genes and their biological functions using differential expression analyses. We observe light-harvesting complex upregulation and cellular framework stability downregulation in altered phenotypes compared to the natural phenotypes. Intertidal macrophytes reduce light capture to avoid photodamage and regulate their morphology to protect against wave damage. In contrast, the lower light conditions and the cultivation environment augment light capture and increase a morphology prioritizing light trapping. Moreover, the addition of simulated wave-sweeping stimuli induces a return to the natural morphology under high-light conditions, showing how mechanical stress affects morphological organization in C. okamurae. We provide detailed gene expression patterns in C. okamurae under varying light intensities and water conditions, suggesting a distinct influence on its morphological traits.

Development of a communication platform for patients with head and neck cancer for effective information delivery and improvement of doctor-patient relationship: application of treatment journey-based service blueprint.

BACKGROUND: Effective communication and information delivery enhance doctor-patient relationships, improves adherence to treatment, reduces work burden, and supports decision-making. The study developed a head and neck cancer (HNC) communication platform to support effective delivery of information about HNC treatment and improve the doctor-patient relationship. METHODS: This study was structured in three main phases: 1) The requirement elicitation phase sought an understanding of the HNC treatment journey and service failure points (FPs) obtained through patient/medical staff interviews and observations, along with a review of the electronic health record system; 2) The development phase involved core needs analysis, solutions development through a co-creation workshop, and validation of the solutions through focus groups; and 3) the proposed HNC communication platform was integrated with the current treatment system, and the flow and mechanism of the interacting services were structured using a service blueprint (SB). RESULTS: Twenty-two service FPs identified through interviews and observations were consolidated into four core needs, and solutions were proposed to address each need: an HNC treatment journey map, cancer survivor stories, operation consent redesign with surgical illustrations, and a non-verbal communication toolkit. The communication platform was designed through the SB in terms of the stage at which the solution was applied and the actions and interactions of the service providers. CONCLUSIONS: The developed platform has practical significance, reflecting a tangible service improvement for both patients and medical staff, making it applicable in hospital settings.

An ortholog of the Vasa intronic gene is required for small RNA-mediated translation repression in Chlamydomonas reinhardtii.

Small RNAs (sRNAs) associate with Argonaute (AGO) proteins in effector complexes, termed RNA-induced silencing complexes (RISCs), which regulate complementary transcripts by translation inhibition and/or RNA degradation. In the unicellular alga Chlamydomonas, several metazoans, and land plants, emerging evidence indicates that polyribosome-associated transcripts can be translationally repressed by RISCs without substantial messenger RNA (mRNA) destabilization. However, the mechanism of translation inhibition in a polyribosomal context is not understood. Here we show that Chlamydomonas VIG1, an ortholog of the Drosophila melanogaster Vasa intronic gene (VIG), is required for this process. VIG1 localizes predominantly in the cytosol and comigrates with monoribosomes and polyribosomes by sucrose density gradient sedimentation. A VIG1-deleted mutant shows hypersensitivity to the translation elongation inhibitor cycloheximide, suggesting that VIG1 may have a nonessential role in ribosome function/structure. Additionally, FLAG-tagged VIG1 copurifies with AGO3 and Dicer-like 3 (DCL3), consistent with it also being a component of the RISC. Indeed, VIG1 is necessary for the repression of sRNA-targeted transcripts at the translational level but is dispensable for cleavage-mediated RNA interference and for the association of the AGO3 effector with polyribosomes or target transcripts. Our results suggest that VIG1 is an ancillary ribosomal component and plays a role in sRNA-mediated translation repression of polyribosomal transcripts.

Enhanced Tumor Uptake and Retention of Cyanine Dye-Albumin Complex for Tumor-Targeted Imaging and Phototherapy.

Heptamethine cyanine dyes are widely used for in vivo near-infrared (NIR) fluorescence imaging and NIR laser-induced cancer phototherapy due to their good optical properties. Since most of heptamethine cyanine dyes available commercially are highly hydrophobic, they can usually be used for in vivo applications after formation of complexes with blood plasma proteins, especially serum albumin, to increase aqueous solubility. The complex formation between cyanine dyes and albumin improves the chemical stability and optical property of the hydrophobic cyanine dyes, which is the bottom of their practical use. In this study, the complexes between three different heptamethine cyanine dyes, namely clinically available indocyanine green (ICG), commercially available IR-786 and zwitterionic ZW800-Cl, and bovine serum albumin (BSA), were prepared to explore the effect of cyanine dyes on their tumor uptake and retention. Among the three complexes, IR-786©BSA exhibited increased tumor accumulation with prolonged tumor retention, compared to other complexes. Moreover, IR-786 bound to BSA played an important role in tumor growth suppression due to its cytotoxicity. To achieve complete tumor ablation, the tumor targeted by IR-786©BSA was further exposed to 808 nm laser irradiation for effective photothermal cancer treatment.

Interdental cleaning and periodontal status among older Koreans: Findings from KNHANES VII.

OBJECTIVE: To assess the association between the usage of interdental cleaning and periodontal status among older people in Korea. BACKGROUND: In order to maintain oral health in older people, it is very important to use interdental cleaning devices. However, there is a lack of research on periodontal status and interdental cleaning device use in older people. METHODS: This study used data collected from the 7th National Health Nutrition Survey (KNHANES VII: 2016-2018). A total of 3426 older people adults aged 65 years or older were selected from 16 489 participants. Data on sociodemographic status (sex, age, level of education, income, residential area), personal health practice (subjective health status, smoking, physical activity, hypertension, and diabetes mellitus), oral health practice (subjective oral health status, tooth brushing frequency, dental visits, and chewing problem), the number of teeth and periodontitis were collected. Periodontitis was defined as having a World Health Organisation community periodontal index (CPI) code greater than or equal to three, and severe periodontitis was defined as a CPI code 4. Participants having a CPI code of 3 or 4 were considered to have periodontal disease in this study. Logistic regression analysis investigated the association between interdental cleaning devices usage and periodontitis controlling the confounding factors. RESULTS: Those who do not use dental floss had a higher rate of periodontal disease (AOR = 1.47, 95% confidence interval [CI]: 1.05 to 2.1). However, there were no significant differences by interdental brush use. In those with 20 or more teeth, non-users of dental floss had a higher risk of periodontitis in all models. Conversely, in those with fewer than 20 teeth, no significant differences were observed. CONCLUSIONS: Older people with mostly intact dentitions have better periodontal health if they clean between their teeth.

Oral health of older Koreans by region and family status in 2020-2021.

OBJECTIVE: To describe the oral health of older people by region and family status using data from the National Health and Nutrition Survey. BACKGROUND: As the ageing of Korean society intensifies, health inequalities based on region and family status are also deepening. METHODS: Data from the 8th National Health and Nutrition Survey (2020-2021) conducted by the Korea Centers for Disease Control and Prevention were used, and a total of 3437 older people aged 65 or older were selected as study participants. Chewing discomfort and oral health behaviours were assessed by region and family status using multivariable logistic regression analysis with the complex sample survey design. RESULTS: We found an association between living alone and greater chewing discomfort. Residing in rural areas was also associated with a higher prevalence of this. In urban areas, chewing discomfort was 1.27 times higher among older people living alone than in those not living alone, while in rural areas, the discomfort was 1.52 times higher among the older people who lived alone. CONCLUSIONS: Region and family status were associated with greater chewing discomfort in older people. In Korean society, where the number of single-person older people households is increasing, along with the ageing population, attention to resolving the disparities in oral health in older people is needed.

Tumor Targeting by Conjugation of Chlorambucil with Zwitterionic Near-Infrared Fluorophore for Cancer Phototherapy.

Improving the tumor targeting of anticancer drugs to minimize systemic exposure remains challenging. The chemical conjugation of anticancer drugs with various near-infrared (NIR) fluorophores may provide an effective approach to improve NIR laser-induced cancer phototherapy. Towards this end, the selection of NIR fluorophores conjugated with hydrophobic anticancer drugs is an important consideration for targeted cancer photothermal therapy (PTT). In this study, a highly water-soluble zwitterionic NIR fluorophore (ZW800) was prepared to conjugate with a water-insoluble anticancer drug, chlorambucil (CLB), to improve tumor targeting, in vivo biodistribution, and PTT performance. The in vivo results using an HT-29 xenograft mouse model demonstrated that the CLB-ZW800 conjugate not only exhibited high tumor accumulation within 4 h after injection, but also showed rapid body clearance behavior for less systemic toxicity. Furthermore, the tumor tissue targeted by the CLB-ZW800 conjugate was exposed to 808 nm NIR laser irradiation to generate photothermal energy and promote apoptotic cell death for the effective PTT of cancer. Therefore, this study provides a feasible strategy for developing bifunctional PTT agents capable of tumor-targeted imaging and phototherapy by the conjugation of small molecule drugs with the versatile zwitterionic NIR fluorophore.

Molecular Tuning of IR-786 for Improved Brown Adipose Tissue Imaging.

To overcome the limitations of brown adipose tissue (BAT) imaging with MRI and PET/CT, near-infrared (NIR) fluorescence imaging has been utilized in living animals because it is highly sensitive, noninvasive, nonradioactive, and cost-effective. To date, only a few NIR fluorescent dyes for detecting BAT have been reported based on the structure-inherent targeting strategy. Among them, IR-786, a commercial cyanine dye, was used firstly for quantitative NIR imaging of BAT perfusion in 2003. Owing to the high cytotoxicity, poor water solubility, and strong nonspecific background uptake of IR-786, the chemical structure of IR-786 should be redesigned to be more hydrophilic and less toxic so that it can show more BAT-specific accumulation. Here, we developed a BAT-specific NIR dye, BF800-AM, by incorporating the tyramine linker in the original structure of IR-786. After modifying the physicochemical properties of IR-786, in vivo results showed significant uptake of the newly designed BF800-AM in the BAT with improved signal-to-background ratio. Additional in vivo studies using mouse tumor models revealed that BF800-AM targeting to BAT is independent of tumor tissues, as distinct from IR-786 showing uptake in both tissues. Therefore, BF800-AM can be used for improved noninvasive visualization of BAT mass and activity in living animals.

Tumor Targeting with Methotrexate-Conjugated Zwitterionic Near-Infrared Fluorophore for Precise Photothermal Therapy.

Targeted tumor imaging can effectively enable image-guided surgery and precise cancer therapy. Finding the right combination of anticancer drugs and near-infrared (NIR) fluorophores is the key to targeted photothermal cancer treatment. In this study, a tumor-targetable NIR fluorophore conjugate with rapid body clearance was developed for accurate tumor imaging and effective photothermal therapy (PTT). The methotrexate (MTX) and zwitterionic NIR fluorophore conjugate (MTX-ZW) were prepared by conjugating a folate antagonist MTX with an aminated ZW800-1 analog to increase the tumor targetability for NIR laser-based PTT of cancer. The MTX, known as a poor tumor-selective drug, showed high tumor accumulation and rapid background clearance after conjugation with the highly water-soluble zwitterionic NIR fluorophore up to 4 h post-injection. The photothermal energy was generated from the MTX-ZW conjugate to induce necrotic cell death in the targeted tumor site under 808 nm laser irradiation. Compared with the previously reported MTX conjugates, the MTX-ZW conjugate can be a great candidate for targeted tumor imaging and fluorescence-guided photothermal cancer therapy. Therefore, these results provide a strategy for the design of drug-fluorophore conjugates and elaborate therapeutic platforms for cancer phototherapy.

A case study on the evaluation of discussion and debate learning effectiveness in a dental hygiene ethics class.

INTRODUCTION: This study introduces the curriculum of a discussion-based learning class for dental hygiene ethics education and evaluates the educational effect of discussion-based learning as applied to a dental hygiene ethics class. MATERIALS AND METHODS: This study was conducted with 48 sophomores from the Department of Dental Hygiene who took dental hygiene ethics in the second semester of 2019. For the DBL class, the following steps were conducted: (1) a pre-class group activity (discussion); (2) a group presentation and team discussion; and (3) a discussion among all groups. To improve the ability to aggregate, organise, and prepare the learner's resources, data, information search skills, and opinions by the team and to improve communication skills by actively listening to other people's opinions, the presentation team's opinions were modified after the discussion, and the performance of rational opinions on topics was added. The professor provided feedback and summarised and ended the discussion. The survey was conducted before and after the DBL class. RESULTS: Concerning critical thinking ability, critical objectivity increased significantly from 8.88 before to 9.38 after the DBL class, and critical confidence also increased significantly. The change in professional attitude significantly increased from 3.21 out of 5 points before the DBL class to 3.53 after the DBL class in the logical and critical thinking skills category and significantly increased from 3.27 to 3.66 in decision-making skills. CONCLUSION: Teaching methods applied in DBL classes, not traditional lecture-style classes, consistent with changing educational paradigms, are very effective and should change gradually. These results will be particularly helpful to faculty members who are inexperienced in DBL courses and performance but interested in them.

Effects of Depression and Resilience of Public Workers on Work-related Stress and Anxiety in Response to the COVID-19 Pandemic.

BACKGROUND: This study explored the clinical variables related to public workers' stress and anxiety regarding the viral epidemic, and the mediating effect of resilience on the relationship between their depression and anxiety in response to coronavirus disease 2019 (COVID-19) pandemic. METHODS: A total of 938 public workers answered anonymous questionnaires in May 2020. The survey included rating scales such as the Stress and Anxiety to Viral Epidemics-9 (SAVE-9), Patients Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), and Connor-Davidson Resilience Scale 2 items (CD-RISC 2), and subjects also answered whether they were employed in COVID-19 related fields. RESULTS: Married, female, junior, public workers reported a higher level of stress and anxiety in response to the viral epidemic. Furthermore, high levels of stress and anxiety toward the epidemic are defined by high PHQ-9, high GAD-7, and low CD-RISC 2 scores. It could also be seen that resilience mediated the effect of depression in public workers and their stress and anxiety levels toward the epidemic. CONCLUSION: It is important to reduce the psychological burden of public workers and manage their mental health to help them cope with the epidemic wisely and efficiently. Among many mental health factors, psychological resilience represents an essential target for psychological intervention among public workers.

Outcomes in patients with cardiac amyloidosis and implantable cardioverter-defibrillator.

AIMS: Cardiac amyloidosis (CA) is associated with increased mortality due to arrhythmias, heart failure, and electromechanical dissociation. However, the role of an implantable cardioverter-defibrillator (ICD) remains unclear. We conducted case-control study to assess survival in CA patients with and without a primary prevention ICD and compared outcomes to an age, sex, and device implant year-matched non-CA group with primary prevention ICD. METHODS AND RESULTS: There were 91 subjects with CA [mean age= 71.2 ± 10.2, female 22.0%, 49 AL with Mayo Stage 2.9 ± 1.0, 41 transthyretin amyloidosis (ATTR), 1 other] followed by Vanderbilt Amyloidosis centre. Patients with ICD (n = 23) were compared with those without (n = 68) and a non-amyloid group with ICD (n = 46). All subjects with ICD had implantation for primary prevention. Mean left ventricular ejection fraction was 36.2% ± 14.4% in CA with ICD, 41.0% ± 10.6% in CA without ICD, and 33.5% ± 14.4% in non-CA patients. Over 3.5 ± 3.1 years, 6 (26.1%) CA, and 12 (26.1%) non-CA subjects received ICD therapies (P = 0.71). Patients with CA had a significantly higher mortality (43.9% vs. 17.4%, P = 0.002) compared with the non-CA group. Mean time from device implantation to death was 21.8 months in AL and 22.8 months in ATTR patients. There was no significant difference in mortality between CA patients who did and did not receive an ICD (39.0% vs. 46.0%, P = 0.59). CONCLUSIONS: Despite comparable event rates patients with CA had a significantly higher mortality and ICDs were not associated with longer survival. With the emergence of effective therapy for AL amyloidosis, further study of ICD is needed in this group.

Transcriptome Analysis of Maternal Gene Transcripts in Unfertilized Eggs of Misgurnus anguillicaudatus and Identification of Immune-Related Maternal Genes.

Maternal genes are important in directing early development and determining egg quality in fish. We here report the de novo transcriptome from four tissue libraries of the cyprinid loach, Misgurnus anguillicaudatus, and for the first time identified maternal gene transcripts in unfertilized eggs and suggest their immune system involvement. Expression profiles and functional enrichment revealed a total 24,116 transcripts were expressed as maternal transcripts in unfertilized eggs, which were involved in a wide range of biological functions and pathways. Comparison expression profiles and analysis of tissue specificity revealed that the large numbers of maternal transcripts were stored in unfertilized eggs near the late phase of ovarian maturation and before ovulation. Functional classification showed a total of 279 maternal immune-related transcripts classified with immune system process GO term and immune system KEGG pathway. qPCR analysis showed that transcript levels of identified maternal immune-related candidate genes were dynamically modulated during development and early ontogeny of M. anguillicaudatus. Taken together, this study could not only provide knowledge on the protective roles of maternal immune-related genes during early life stage of M. anguillicaudatus but could also be a valuable transcriptomic/genomic resource for further analysis of maternally provisioned genes in M. anguillicaudatus and other related teleost fishes.

Subfunctionalization and evolution of liver-expressed antimicrobial peptide 2 (LEAP2) isoform genes in Siberian sturgeon (Acipenser baerii), a primitive chondrostean fish species.

Two liver-expressed antimicrobial peptide 2 (LEAP2) isoforms were characterized in a primitive chondrostean sturgeon species, Acipenser baerii (Acipenseriformes). A. baerii LEAP2 isoforms represented essentially common structures shared by their vertebrate orthologs at both genomic (i.e., tripartite organization) and peptide (two conserved disulfide bonds) levels. A. baerii LEAP2 isoforms (designed LEAP2AB and LEAP2C, respectively) phylogenetically occupy the most basal position in the actinopterygian lineage and represent an intermediate character between teleostean and tetrapodian LEAP2s in the sequence alignment. Molecular phylogenetic analysis including LEAP2s from extant primitive fish species indicated that the evolutionary origin of ancestral LEAP2 in vertebrate groups should date back to earlier than the actinopterygian-sarcopterygian split. Gene expression assays under both basal and stimulated conditions suggested that A. baerii LEAP2 isoforms have undergone substantial subfunctionalization in tissue distribution pattern, developmental/ontogenetic expression, and immune responses. LEAP2AB showed a predominant liver expression, while LEAP2C exhibited the highest level of expression in the intestine. LEAP2C was a more dominantly expressed isoform during embryonic development and prelarval ontogeny. The LEAP2AB isoform is more closely associated with innate immune response to microbial invasion, compared with LEAP2C, as evidenced by results from LPS, poly(I:C) and Aeromonas hydrophila challenges. Synthetic mature peptides of LEAP2AB displayed a more potent antimicrobial activity than did LEAP2C. Data from this study could be useful not only to provide deeper insights into the evolutionary mechanism of LEAP2 in the actinopterygian lineage but also to better understand the innate immunity of this commercially important chondrostean species.

Chondrostean sturgeon hepcidin: An evolutionary link between teleost and tetrapod hepcidins.

Hepcidin, a cysteine-rich antimicrobial peptide (AMP), plays key roles as a regulatory hormone in iron homeostasis, providing a link between iron metabolism and innate immunity. Unlike many other AMPs displaying a high degree of sequence variability among closely related organisms, hepcidin is highly conserved from teleosts to mammals. However, little is known about the early ancestry of hepcidins in the vertebrate lineage. Here, we first report potential a prototype hepcidin from the Siberian sturgeon Acipenser baerii, a primitive chondrostean species. The A. baerii hepcidin (AbHAMP) gene showed a tripartite exon-intron organization, which encoded a precursor protein comprised of three structural signatures containing eight cysteine residues, a common structure in vertebrate hepcidin genes and proteins. mRNA expression by iron-overloading and bacterial infection and antibacterial activity revealed that AbHAMP might play a role in iron metabolism regulator in the liver, and in direct and/or indirect host immune response in the kidney against invading pathogen. Comparison of gene and protein sequences reveled that AbHAMP possesses intermediate characteristics between tetrapodian and teleostean hepcidins (HAMP1s). Phylogenetically, AbHAMP had a closer genetic affiliation to tetrapodian orthologs than to teleostean orthologs, suggesting that the structures of this chondrostean hepcidin may closely reflect the structures of an evolutionarily ancestral form that might have evolved into extant hepcidins in tetrapods and teleosts, respectively. Based on the identification of hepcidin from the chondrostean group, the emergence of the common ancestral hepcidin should be traced back to in early Osteichthyes: no later than sarcopterygian (lobe-finned fishes) - actinopterygian (ray-finned fishes) split.