Identification and functional analyses of CD4-1+ cells in grass carp (Ctenopharyngodon idella).

In mammals, CD4 is found to be expressed on T cells and innate immune cells, however, teleost cells bearing CD4 have not been well identified and characterized. In this study, we identified two different CD4-1+ cell subsets in grass carp (Ctenopharyngodon idella): CD4-1+ lymphocytes (Lym) and CD4-1+ myeloid cells (Mye), both of which had the highest proportions in the head kidney. The mRNA expression analysis showed that CD4-1, CD4-2, TCRß, CD3γ/δ, and LCK1 are highly expressed in CD4-1+ Lym and also expressed in CD4-1+ Mye. Furthermore, we found that CD4-1+ Lym have a Lym morphology and highly express T-cell cytokines, suggesting that they are CD4+ T cells equivalent to mammalian Th cells. On the other hand, CD4-1+ Mye were found to have a morphology of macrophage and highly express macrophage marker gene MCSFR, indicating that they are macrophages. In addition, functional analysis revealed that CD4-1+ Mye possess phagocytic ability and great antigen-processing ability. Taken together, our study sheds further light on the composition and function of CD4+ cells in teleost fish.

Supramolecular copolymerization of hydrophobic and hydrophilic monomers in liquid crystalline media.

In the case of covalent polymers, immiscible polymers can be integrated by covalently linking them together, but such a strategy is not possible in supramolecular polymers. Here we report the supramolecular copolymerization of two porphyrin-based monomers, C10P2H and TEGPCu with side chains bearing cyanobiphenyl (CB) groups at the ends of hydrophobic alkyl or hydrophilic tetraethylene glycol chains, respectively. These monomers undergo self-sorting supramolecular polymerization in highly diluted solutions ([monomer] = 3.4 × 10-9 mol% (2.0 × 10-8 mol L-1)) in nonpolar media due to the incompatibility of the side chains. Surprisingly, these monomers undergo supramolecular copolymerization under high concentration conditions ([monomer] = 7.7 mol%) in the medium of 4-cyano-4'-pentyloxybiphenyl (5OCB) to form a columnar liquid crystalline phase under thermodynamic conditions, where the individual columns are composed of supramolecular block copolymers. The combination of CB ends of both monomers and the 5OCB medium is essential for the two monomers to form an integrated structure in a condensed system without phase separation.

Antimicrobial Protein LECT2-b Helps Maintain Gut Microbiota Homeostasis via Selectively Targeting Certain Pathogenic Bacteria.

Antimicrobial peptides/proteins (AMPs) constitute a critical component of gut immunity in animals, protecting the gut from pathogenic bacteria. However, the interactions between AMPs and gut microbiota remain elusive. In this study, we show that leukocyte-derived chemotaxin-2 (LECT2)-b, a recently discovered AMP, helps maintain gut homeostasis in grass carp (Ctenopharyngodon idella), one of the major farmed fish species globally, by directly regulating the gut microbiota. Knockdown of LECT2-b resulted in dysregulation of the gut microbiota. Specifically, LECT2-b deficiency led to the dominance of Proteobacteria, consisting of proinflammatory bacterial species, over Firmicutes, which includes anti-inflammatory bacteria. In addition, the opportunistic pathogenic bacteria genus Aeromonas became the dominant genus replacing the probiotic bacteria Lactobacillus and Bacillus. Further analysis revealed that this effect was due to the direct and selective inhibition of certain pathogenic bacterial species by LECT2-b. Moreover, LECT2-b knockdown promoted biofilm formation by gut microbiota, resulting in tissue damage and inflammation. Importantly, LECT2-b treatment alleviated the negative effects induced by LECT2-b knockdown. These findings highlight the crucial role of LECT2-b in maintaining the gut microbiota homeostasis and mucosal health. Overall, our study provides important data for understanding the roles of AMPs in the regulation of gut homeostasis in animals.

An Atlas of Grass Carp IgM+ B Cells in Homeostasis and Bacterial Infection Helps to Reveal the Unique Heterogeneity of B Cells in Early Vertebrates.

Teleost B cells are primitive lymphocytes with both innate and adaptive immune functions. However, the heterogeneity and differentiation trajectory of teleost B cells remain largely unknown. In this study, the landscape of grass carp IgM+ (gcIgM+) B cells was revealed by single-cell RNA sequencing. The results showed that gcIgM+ B cells mainly comprise six populations: (im)mature B cells, innate B cells, proliferating B cells, plasma cells, CD22+ cells, and CD34+ cells, among which innate B cells and proliferating B cells were uncommon B cell subsets with, to our knowledge, new characteristics. Remarkably, three functional IgMs were discovered in grass carp, and a significant percentage of gcIgM+ B cells, especially plasma cells, expressed multiple Igµ genes (Igµ1, Igµ2, and/or Igµ3). More importantly, through single-cell sorting combined with Sanger sequencing, we found that distinct VHDJH recombination patterns of Igµ genes were present in single IgM+ B cells, indicating that individual teleost B cells might produce multiple Abs by coexpressing rearranged IgM subclass genes. Moreover, the percentage of IgM1highIgM2highIgM3high plasma cells increased significantly after bacterial infection, suggesting that individual plasma cells might tend to produce multiple IgMs to resist the infection in teleost fish. In summary, to our knowledge, this study not only helps to uncover the unique heterogeneity of B cells in early vertebrates but also provided significant new evidence supporting the recently proposed "one cell-multiple Abs" paradigm, challenging the classical rule of "one cell-one Ab."

Combination of canagliflozin and puerarin alleviates the lipotoxicity to diabetic kidney in mice.

Diabetic kidney disease is one of the most serious complications of diabetes. Although diabetic kidney disease can be effectively controlled through strict blood glucose management and corresponding symptomatic treatment, these therapies cannot reduce its incidence in diabetic patients. The sodium-glucose cotransporter 2 (SGLT2) inhibitors and the traditional Chinese herb "Gegen" have been widely used in diabetes-related therapy. However, it remains unclear whether the combined use of these two kinds of medicines contributes to an increased curative effect on diabetic kidney disease. In this study, we examined this issue by evaluating the efficacy of the combination of puerarin, an active ingredient of Gegen, and canagliflozin, an SGLT2 inhibitor for a 12-week intervention using a mouse model of diabetes. The results indicated that the combination of puerarin and canagliflozin was superior to canagliflozin alone in improving the metabolic and renal function parameters of diabetic mice. Our findings suggested that the renoprotective effect of combined puerarin and canagliflozin in diabetic mice was achieved by reducing renal lipid accumulation. This study provides a new strategy for the clinical prevention and treatment of diabetic kidney disease. The puerarin and SGLT2 inhibitor combination therapy at the initial stage of diabetes may effectively delay the occurrence of diabetic kidney injury, and significantly alleviate the burden of renal lipotoxicity.

Preparation of the monoclonal antibody against Nile tilapia Igλ and study on the Igλ+ B cell subset in Nile tilapia.

Immunoglobulins (Igs) are important effector molecules that mediate humoral immunity. A typical Ig consists of two heavy and two light chains. In teleosts, three Ig heavy chain isotypes (Igµ, Igδ and Igτ) and three Ig light chain isotypes (Igκ, Igλ and Igσ) have been identified. Compared to the heavy chains, teleost Ig light chains have been poorly studied due to the lack of antibodies. In this study, a mouse anti-Nile tilapia Igλ monoclonal antibody (mAb) was prepared, which could specifically recognize Igλ in serum and Igλ+ B cells in tissues. Further, the composition of IgM+ and Igλ+ B cell subsets was analyzed using this antibody and a mouse anti-tilapia IgM heavy chain mAb. The ratio of IgM+Igλ+ B cells to total IgM+ B cells in head kidney and peripheral blood was about 30%, while that in spleen was about 50%; the ratio of IgM-Igλ+ B cells to total Igλ+ B cells in head kidney and peripheral blood was about 45%, while that in spleen was about 25%. The IgM-Igλ+ B cells was speculated to be IgT+ B cells. Finally, we detected an increase in the level of specific antibodies against the surface antigen-Sip of Streptococcus agalactiae in serum after S. agalactiae infection, indicating that mouse anti-tilapia Igλ mAb can be used to detect the antibody level after immunization of Nile tilapia, which lays a foundation for the evaluation of immunization effect of tilapia vaccine.

Comparative study on antibacterial characteristics of the multiple liver expressed antimicrobial peptides (LEAPs) in teleost fish.

Antimicrobial peptides are important components of the host innate immune system, forming the first line of defense against infectious microorganisms. Among them, liver-expressed antimicrobial peptides (LEAPs) are a family of antimicrobial peptides that widely exist in vertebrates. LEAPs include two types, named LEAP-1 and LEAP-2, and many teleost fish have two or more LEAP-2s. In this study, LEAP-2C from rainbow trout and grass carp were discovered, both of which are composed of 3 exons and 2 introns. The antibacterial functions of the multiple LEAPs were systematically compared in rainbow trout and grass carp. The gene expression pattern revealed that rainbow trout and grass carp LEAP-1, LEAP-2A, LEAP-2B and/or LEAP-2C were differentially expressed in various tissues/organs, mainly in liver. After bacterial infection, the expression levels of LEAP-1, LEAP-2A, LEAP-2B and/or LEAP-2C in the liver and gut of rainbow trout and grass carp increased to varying degrees. Moreover, the antibacterial assay and bacterial membrane permeability assay showed that rainbow trout and grass carp LEAP-1, LEAP-2A, LEAP-2B and LEAP-2C all have antibacterial activities against a variety of Gram-positive and Gram-negative bacteria with varying levels through membrane rupture. Furthermore, cell transfection assay showed that only rainbow trout LEAP-1, but not LEAP-2, can lead to the internalization of ferroportin, the only iron exporter on cell surface, indicating that only LEAP-1 possess iron metabolism regulation activity in teleost fish. Taken together, this study systematically compared the antibacterial function of LEAPs in teleost fish and the results suggest that multiple LEAPs can enhance the immunity of teleost fish through different expression patterns and different antibacterial activities to various bacteria.

Insights into the Antibacterial Properties of Complement Peptides C3a, C4a, and C5a across Vertebrates.

Complement peptides C3a, C4a, and C5a are important components of innate immunity in vertebrates. Although they diverged from a common ancestor, only C3a and C4a can act as antibacterial peptides in Homo sapiens, suggesting that C5a has evolved into a purely chemotactic molecule; however, the antibacterial properties of C3a, C4a, and C5a across vertebrates still require elucidation. In this article, we show that, unlike those in H. sapiens, Mus musculus C3a, C4a, and C5a all possess antibacterial activities, implying that the antibacterial properties of C3a, C4a, and C5a have evolved divergently in vertebrates. The extremely different net charge, a key factor determining the antibacterial activities of cationic antimicrobial peptides, of vertebrate C3a, C4a, and C5a supports this speculation. Moreover, the antibacterial activity of overlapping peptides covering vertebrate C3a, C4a, and C5a further strongly supports the speculation, because their activity is positively correlated with the net charge of source molecules. Notably, the structures of C3a, C4a, and C5a are conserved in vertebrates, and the inactive overlapping peptides can become antibacterial peptides if mutated to possess enough net positive charges, indicating that net charge is the only factor determining the antibacterial properties of vertebrate C3a, C4a, and C5a. More importantly, many vertebrate C3a-, C4a-, and C5a-derived peptides possess high antibacterial activities yet exhibit no hemolytic activities, suggesting the application potential in anti-infective therapy. Taken together, our findings reveal that vertebrate C3a, C4a, and C5a are all sources of antibacterial peptides that will facilitate the design of excellent peptide antibiotics.

Insights into the Antibacterial Properties of Complement Peptides C3a, C4a, and C5a across Vertebrates.

Complement peptides C3a, C4a, and C5a are important components of innate immunity in vertebrates. Although they diverged from a common ancestor, only C3a and C4a can act as antibacterial peptides in Homo sapiens, suggesting that C5a has evolved into a purely chemotactic molecule; however, the antibacterial properties of C3a, C4a, and C5a across vertebrates still require elucidation. In this article, we show that, unlike those in H. sapiens, Mus musculus C3a, C4a, and C5a all possess antibacterial activities, implying that the antibacterial properties of C3a, C4a, and C5a have evolved divergently in vertebrates. The extremely different net charge, a key factor determining the antibacterial activities of cationic antimicrobial peptides, of vertebrate C3a, C4a, and C5a supports this speculation. Moreover, the antibacterial activity of overlapping peptides covering vertebrate C3a, C4a, and C5a further strongly supports the speculation, because their activity is positively correlated with the net charge of source molecules. Notably, the structures of C3a, C4a, and C5a are conserved in vertebrates, and the inactive overlapping peptides can become antibacterial peptides if mutated to possess enough net positive charges, indicating that net charge is the only factor determining the antibacterial properties of vertebrate C3a, C4a, and C5a. More importantly, many vertebrate C3a-, C4a-, and C5a-derived peptides possess high antibacterial activities yet exhibit no hemolytic activities, suggesting the application potential in anti-infective therapy. Taken together, our findings reveal that vertebrate C3a, C4a, and C5a are all sources of antibacterial peptides that will facilitate the design of excellent peptide antibiotics.

Molecular and Functional Analyses of the Primordial Costimulatory Molecule CD80/86 and Its Receptors CD28 and CD152 (CTLA-4) in a Teleost Fish.

The moderate activation of T cells in mammals requires the costimulatory molecules, CD80 and CD86, on antigen-presenting cells to interact with their respective T cell receptors, CD28 and CD152 (CTLA-4), to promote costimulatory signals. In contrast, teleost fish (except salmonids) only possess CD80/86 as their sole primordial costimulatory molecule. However, the mechanism, which underlies the interaction between CD80/86 and its receptors CD28 and CD152 still requires elucidation. In this study, we cloned and identified the CD80/86, CD28, and CD152 genes of the grass carp (Ctenopharyngodon idella). The mRNA expression analysis showed that CD80/86, CD28, and CD152 were constitutively expressed in various tissues. Further analysis revealed that CD80/86 was highly expressed in IgM+ B cells. Conversely, CD28 and CD152 were highly expressed in CD4+ and CD8+ T cells. Subcellular localization illustrated that CD80/86, CD28, and CD152 are all located on the cell membrane. A yeast two-hybrid assay exhibited that CD80/86 can bind with both CD28 and CD152. In vivo assay showed that the expression of CD80/86 was rapidly upregulated in Aeromonas hydrophila infected fish compared to the control fish. However, the expression of CD28 and CD152 presented the inverse trend, suggesting that teleost fish may regulate T cell activation through the differential expression of CD28 and CD152. Importantly, we discovered that T cells were more likely to be activated by A. hydrophila after CD152 was blocked by anti-CD152 antibodies. This suggests that the teleost CD152 is an inhibitory receptor of T cell activation, which is similar to the mammalian CD152. Overall, this study begins to define the interaction feature between primordial CD80/86 and its receptors CD28 and CD152 in teleost fish, alongside providing a cross-species understanding of the evolution of the costimulatory signals throughout vertebrates.

LECT2 Is a Novel Antibacterial Protein in Vertebrates.

In vertebrates, leukocyte-derived chemotaxin-2 (LECT2) is an important immunoregulator with conserved chemotactic and phagocytosis-stimulating activities to leukocytes during bacterial infection. However, whether LECT2 possesses direct antibacterial activity remains unknown. In this article, we show that, unlike tetrapods with a single LECT2 gene, two LECT2 genes exist in teleost fish, named LECT2-a and LECT2-b Using grass carp as a research model, we found that the expression pattern of grass carp LECT2-a (gcLECT2-a) is more similar to that of LECT2 in tetrapods, while gcLECT2-b has evolved to be highly expressed in mucosal immune organs, including the intestine and skin. Interestingly, we found that gcLECT2-b, with conserved chemotactic and phagocytosis-stimulating activities, can also kill Gram-negative and Gram-positive bacteria directly in a membrane-dependent and a non-membrane-dependent manner, respectively. Moreover, gcLECT2-b could prevent the adherence of bacteria to epithelial cells through agglutination by targeting peptidoglycan and lipoteichoic acid. Further study revealed that gcLECT2-b can protect grass carp from Aeromonas hydrophila infection in vivo, because it significantly reduces intestinal necrosis and tissue bacterial load. More importantly, we found that LECT2 from representative tetrapods, except human, also possesses direct antibacterial activities, indicating that the direct antibacterial property of LECT2 is generally conserved in vertebrates. Taken together, to our knowledge, our study discovered a novel function of LECT2 in the antibacterial immunity of vertebrates, especially teleost fish, greatly enhancing our knowledge of this important molecule.

Complement C3a Enhances the Phagocytic Activity of B Cells Through C3aR in a Fish.

The complement system is an important part of the immune system of teleost fish. Besides, teleost B cells possess both phagocytic activity and adaptive humoral immune function, unlike mammalian B1 cells with phagocytic activity and B2 cells specific to adaptive humoral immunity. However, the cross talk between complement system and phagocytic B cells in teleost fish still requires elucidation. Here, we show that, unlike tetrapods with a single C3 gene, nine C3 genes were identified from the grass carp (Ctenopharyngodon idella) genome, named C3.1-C3.9. Expression analysis revealed that C3.1 is the dominant C3 molecule in grass carp, for its expression was significantly higher than that of the other C3 molecules both at the mRNA and protein levels. The C3a fragment of C3.1 (C3a.1) was determined after the conserved C3 convertase cleavage site. Structural analysis revealed that C3a.1 consists of four α-helixes, with the C-terminal region forming a long α-helix, which is the potential functional region. Interestingly, we found that the recombinant GST-C3a.1 protein and the C-terminal α-helix peptide of C3a.1 both could significantly enhance the phagocytic activity of IgM+ B cells. Further study revealed that the C3a receptor (C3aR) was highly expressed in grass carp IgM+ B cells, and the phagocytosis-stimulating activity of C3a.1 could be dramatically inhibited by the anti-C3aR antibodies, indicating that C3a.1 performed the stimulating function through C3aR on IgM+ B cells. Taken together, our study not only uncovered the novel phagocytosis-stimulating activity of C3a, but also increased our knowledge of the cross talk between complement system and phagocytic B cells in teleost fish.

Chromosome-level genome assembly of grass carp (Ctenopharyngodon idella) provides insights into its genome evolution.

BACKGROUND: The grass carp has great economic value and occupies an important evolutionary position. Genomic information regarding this species could help better understand its rapid growth rate as well as its unique body plan and environmental adaptation. RESULTS: We assembled the chromosome-level grass carp genome using the PacBio sequencing and chromosome structure capture technique. The final genome assembly has a total length of 893.2 Mb with a contig N50 of 19.3 Mb and a scaffold N50 of 35.7 Mb. About 99.85% of the assembled contigs were anchored into 24 chromosomes. Based on the prediction, this genome contained 30,342 protein-coding genes and 43.26% repetitive sequences. Furthermore, we determined that the large genome size can be attributed to the DNA-mediated transposable elements which accounted for 58.9% of the repetitive sequences in grass carp. We identified that the grass carp has only 24 pairs of chromosomes due to the fusion of two ancestral chromosomes. Enrichment analyses of significantly expanded and positively selected genes reflected evolutionary adaptation of grass carp to the feeding habits. We also detected the loss of conserved non-coding regulatory elements associated with the development of the immune system, nervous system, and digestive system, which may be critical for grass carp herbivorous traits. CONCLUSIONS: The high-quality reference genome reported here provides a valuable resource for the genetic improvement and molecular-guided breeding of the grass carp.

Anomalous Chiral Transfer: Supramolecular Polymerization in a Chiral Medium of a Mesogenic Molecule.

Here, we report a medium-to-polymer anomalous chiral transfer in the supramolecular polymerization of a tetraphenylporphyrin-based achiral hydrogen-bonding monomer (TPP) in a chiral medium of 5-cyanobiphenyl CB*. A mixture of TPP in (R)-CB* ([TPP]=7.7 mol %) at 40 °C gave a columnar oblique LC mesophase, where the individual columns were composed of an optically active helical supramolecular polymer of TPP as a consequence of a successful medium-to-polymer chiral transfer. Meanwhile, upon dilution of CB* with achiral 5-cyanobiphenyl CB, the optical activity of the system showed an anomalous bell-shaped dependency on the composition of CB*/CB, where the gabs value of 0.049 at CB*/CB=50/50 was 6.0 times larger than the gabs value of CB* alone. Such anomalous chiroptical amplification in CD is most likely due to a change in the stacking geometry of TPP in the oblique columnar LC upon lateral compression.

Plasmablasts induced by chitosan oligosaccharide secrete natural IgM to enhance the humoral immunity in grass carp.

Chitosan oligosaccharide (COS) is an attractive immunopotentiator capable of driving humoral immunity in vertebrates, but its cellular and molecular mechanisms still require elucidation. In this study, COS induced the proliferation and differentiation of splenic IgM+ B cells into IgMlo and IgMhi B cell subsets in grass carp (Ctenopharyngodon idella). The IgMlo B cells were further identified as short-lived plasmablasts that secreted natural IgM with binding-abilities to lipopolysaccharide (LPS) and peptidoglycan (PGN). Moreover, the mannose receptor (MR) and integrins were discovered and identified as the binding-receptors of COS on IgMlo plasmablasts. The MR synergized with integrins to trigger intracellular signal transduction to boost plasmablast generation and expansion. Notably, IgMlo plasmablasts originally generated in spleen but they migrated into blood to secrete natural IgM, which augmented the serum bactericidal activity. Taken together, this study revealed the cellular and molecular mechanisms of COS-triggered humoral immunity in fish.

Elevated serum neurofilament light chain in children autism spectrum disorder: A case control study.

OBJECTIVE: We aimed to assess serum neurofilament light chain (sNfL) levels in autism spectrum disorder (ASD) and to investigate whether they are related to the severity of disease. METHODS: The cohorts consisted of 166 children aged 3-8 (83 children diagnosed with ASD and 83 children with typically-developing). sNfL were analyzed using Single Molecule Array (Simoa) technology. ASD symptom severity was assessed according to the Chinese version of the Childhood Autism Rating Scale (CARS) score. RESULTS: The mean age of those included ASD was 5.1 years (standard deviations [S.D.]: 1.7) and 78.3 % were boys. The mean (SD) sNfL concentrations were significantly (P < 0.001) higher in ASD than in TP children (10.2[5.0] pg/mL and 7.1[3.2]pg/mL). For each 1 pg/mL increase of sNfL, the risk of ASD would increase by 19 % (with the OR unadjusted of 1.19 [95 % CI 1.10-1.29], P < 0.001) and 11 % (with the OR adjusted of 1.11 [1.03-1.23], P < 0.001), respectively. sNfL concentrations in children with severe ASD were higher than in those children with mild-to-moderate ASD (12.4[5.1] pg/mL vs. 8.3[4.2]pg/mL; P < 0.001). Among ASD cases, each 1 pg/mL increase of sNfL is associated with 20 % higher unadjusted or 11 % higher adjusted odds, respectively, of severe (vs. mild-to-moderate) ASD. CONCLUSIONS: The data showed that sNfL was elevated in ASD and related to symptom severity, suggesting that sNfL may play a role in ASD progression.

Splicing variants of grass carp (Ctenopharyngodon idellus) IL-21: Functions in IgM+ B cell proliferation and IgM secretion.

In mammals, interleukin 21 (IL-21) is a type I four-helical bundle cytokine produced by activated T cells that has pleiotropic functions on immune cells. Although IL-21 has been discovered in fish, the splicing variants of this cytokine and their functions on B cells are unclear. In this study, based on the original transcript of grass carp IL-21 (named gcIL-21sv1 in this study), two alternative splicing variants, named gcIL-21sv2 and gcIL-21sv3, were cloned and characterized. The protein sequences of gcIL-21sv1 and gcIL-21sv2 consist of four α-helixes, and only the six amino acid residues at the C-terminal are different. Unlike gcIL-21sv1 and gcIL-21sv2, gcIL-21sv3 lacks the C-terminal region. The expression analysis showed that gcIL-21sv1, gcIL-21sv2, and gcIL-21sv3 were constitutively expressed in all the tested tissues, and their expression could be significantly up-regulated by LPS and Poly (I:C) in head kidney leukocytes (HKLs), with the fold change of gcIL-21sv1 being higher than that of gcIL-21sv2 and gcIL-21sv3. Recombinant gcIL-21sv1 and gcIL-21sv2, but not gcIL-21sv3, could induce the proliferation of IgM+ B cells and the secretion of IgM, with the activity of gcIL-21sv1 being stronger than that of gcIL-21sv2, indicating that the C-terminal region plays important roles in the function of gcIL-21. Taken together, this study found that, like IL-21 in human and mouse, IL-21 splicing variants also exist in fish, and the regulatory activities of these variants in humoral immunity are differ, suggesting that grass carp may balance the immune response mediated by IL-21 through alternative splicing.

Membrane IgM+ plasma cells in grass carp (Ctenopharyngodon idella): Insights into the conserved evolution of IgM+ plasma cells in vertebrates.

Teleost fish are the most primitive bony vertebrates that contain B cells; thus, comparative analysis of teleost naïve/mature B cells and plasma cells can provide helpful evidence for understanding the evolution paradigms of these two B-cell subpopulations in vertebrates. In this study, we developed monoclonal antibody against grass carp IgM and identified two different IgM+ cell subsets: IgM+ lymphocytes (Lym), resembling naïve/mature B cells, and IgM+ myeloid cells (Mye), resembling plasma cells. Like plasma cells in mammals, the size of IgM+ Mye is significantly larger than that of IgM+ Lym, as revealed by flow cytometric analysis and transmission electron microscopy. The IgM+ Mye were further verified as plasma cells because they showed gene expression patterns similar with those of human plasma cells and a great capacity to secrete IgM. Like mammalian IgM+ and IgA+ plasma cells, not IgG+ plasma cells, grass carp IgM+ Mye also expressed membrane immunoglobulins, a feature conserved in IgM+ plasma cells in vertebrates. Furthermore, recombinant CD40L or IL-21 alone could induce the plasma cell generation and IgM secretion, while the combination of CD40L and IL-21 had greater effect on IgM secretion, but not on plasma cell generation. This study fills an important gap in the knowledge of plasma cells in teleost fish and provides critical insights into the conserved evolution of IgM+ plasma cells in vertebrates.

Supramolecular Polymerization in Liquid Crystalline Media: Toward Modular Synthesis of Multifunctional Core-Shell Columnar Liquid Crystals.

Recently, we discovered a modular synthetic approach for constructing core-shell columnar liquid crystals (LCs) by supramolecular polymerization in LC media. In the present work, we successfully confirmed that our modular synthetic approach has the potential to be widely extended to the development of multifunctional columnar LCs. Herein, we constructed the first core-shell columnar LC that was proved to be orientable by both electric and magnetic fields by the supramolecular polymerization of NODiskNH* in a nematic LC medium of 4-cyano-4'-pentyloxybiphenyl (5OCB). NODiskNH* is a chiral benzenetricarboxamide derivative bearing 2,2,6,6-tetramethylpiperidine 1-oxyl termini, which is known to form a helical supramolecular polymer via a triple hydrogen-bonding array. NODiskNH* alone formed a hydrogen-bonded liquid phase without any long-range structural ordering. However, a nematic LC medium of 5OCB, when mixed with NODiskNH* at a molar ratio of 1:3, underwent a "structural order-increasing" mesophase transition, affording an optically active single LC phase with a hexagonally arranged core-shell columnar geometry in a temperature range from 113 to 51 °C. Unprecedentedly, this core-shell columnar LC can orient its columns both electrically and magnetically, resulting in unidirectional columnar ordering.

Molecular and functional characterization of the indoleamine 2,3-dioxygenase in grass carp (Ctenopharyngodon idella).

Indoleamine 2,3-dioxygenase (IDO) is a kind of dioxygenase that can catalyze the degradation of levo-tryptophan (L-Trp) and plays key roles in immune tolerance. In this study, the IDO gene was cloned and functionally characterized from grass carp (gcIDO). The results showed that gcIDO overexpressed in GCO cells could catalyze the degradation of L-Trp through the L-Trp - kynurenine pathway, and this activity could be promoted by δ-aminolevulinic acid (ALA) while inhibited by levo-1-methyl tryptophan (L-1MT). Moreover, gcIDO was constitutively expressed in various tissues, and its expression could be significantly up-regulated by LPS and Poly (I:C) in peripheral blood leukocytes (PBLs). Furthermore, recombinant TGF-ß1 of grass carp could up-regulate the expression of IDO, TGF-ß1, CD25, and Foxp3 in PBLs, indicating that the TGF-ß1/IDO pathway is present in fish. In the soybean meal induced enteritis (SBMIE) model, the expression of gcIDO in the intestine was up-regulated significantly, demonstrating that gcIDO may play an immunoregulatory role in SBMIE. Taken together, these data suggest that the IDO plays multiple roles in the immunity of fish.