TLR3/TRIF and MAVS Signaling Is Essential in Regulating Mucosal T Cell Responses during Rotavirus Infection.

The functions of the natural dsRNA sensors TLR3 (TRIF) and RIG-I (MAVS) are crucial during viral challenge and have not been accurately clarified in adaptive immune responses to rotavirus (RV) infection. In this study, we found that RV infection caused severe pathological damage to the small intestine of TLR3-/- and TRIF-/- mice. Our data found that dendritic cells from TLR3-/- and TRIF-/- mice had impaired Ag presentation to the RV and attenuated initiation of T cells upon viral infection. These attenuated functions resulted in impaired CD4+ T and CD8+ T function in mice lacking TLR3-TRIF signaling postinfection. Additionally, attenuated proliferative capacity of T cells from TLR3-/- and TRIF-/- mice was observed. Subsequently, we observed a significant reduction in the absolute number of memory T cells in the spleen and mesenteric lymph node (MLN) of TRIF-/- recipient mice following RV infection in a bone marrow chimeric model. Furthermore, there was reduced migration of type 2 classical dendritic cells from the intestine to MLNs after RV infection in TLR3-/- and TRIF-/- mice. Notably, RV infection resulted in attenuated killing of spleen and MLN tissues in TRIF-/- and MAVS-/- mice. Finally, we demonstrated that RV infection promoted apoptosis of CD8+ T cells in TRIF-/- and TLR3-/-MAVS-/- mice. Taken together, our findings highlight an important mechanism of TLR3 signaling through TRIF in mucosal T cell responses to RV and lay the foundation for the development of a novel vaccine.

Acanthopanax senticosus cultures fermented by Lactobacillus rhamnosus enhanced immune response through improvement of antioxidant activity and inflammation in crucian carp (Carassius auratus).

Lactic acid bacteria (LAB) have been recognized as safe microorganism that improve micro-flora disturbances and enhance immune response. A well-know traditional herbal medicine, Acanthopanax senticosus (As) was extensively utilized in aquaculture to improve growth performance and disease resistance. Particularly, the septicemia, skin wound and gastroenteritis caused by Aeromonas hydrophila threaten the health of aquatic animals and human. However, the effects of probiotic fermented with A. senticosus product on the immune regulation and pathogen prevention in fish remain unclear. Here, the aim of the present study was to elucidate whether the A. senticosus fermentation by Lactobacillus rhamnosus improve immune barrier function. The crucian carp were fed with basal diet supplemented with L. rhamnosus fermented A. senticosus cultures at 2 %, 4 %, 6 % and 8 % bacterial inoculum for 8 weeks. After trials, the weight gain rate (WGR), specific growth rate (SGR) were significantly increased, especially in LGG-6 group. The results confirmed that the level of the CAT, GSH-PX, SOD, lysozyme, and MDA was enhanced in fish received with probiotic fermented product. Moreover, the L. rhamnosus fermented A. senticosus cultures could trigger innate and adaptive immunity, including the up-regulation of the C3, C4, and IgM concentration. The results of qRT-PCR revealed that stronger mRNA transcription of IL-1ß, IL-10, IFN-γ, TNF-α, and MyD88 genes in the liver, spleen, kidney, intestine and gills tissues of fish treated with probiotic fermented with A. senticosus product. After infected with A. hydrophila, the survival rate of the LGG-2 (40 %), LGG-4 (50 %), LGG-6 (60 %), LGG-8 (50 %) groups was higher than the control group. Meanwhile, the pathological damage of the liver, spleen, head-kidney, and intestine tissues of probiotic fermentation-fed fish could be alleviated after pathogen infection. Therefore, the present work indicated that L. rhamnosus fermented A. senticosus could be regard as a potential intestine-target therapy strategy to protecting fish from pathogenic bacteria infection.

Immunoprotective effect of recombinant Lactobacillus plantarum expressing largemouth bass virus MCP on largemouth bass.

Largemouth bass virus (LMBV) is an infectious pathogen that causes high mortality rates in largemouth bass, and outbreaks of this virus can significantly harm the aquaculture industry. Currently, no vaccine has been developed that can effectively prevent the transmission of LMBV. In this study, we constructed a recombinant Lactobacillus plantarum (L. plantarum) strain capable of expressing the MCP gene of LMBV and displaying this protein on its surface; then, we evaluated the immunoprotective effect of this recombinant bacterium on largemouth bass. Western blotting, immunofluorescence, and flow cytometry confirmed that MCP was successfully expressed and anchored on the surfaces of NC8 cells. Immunization of largemouth bass with NC8-pSIP409-pgsA'-MCP via the oral feeding route induced CD4, CD8, IL-1ß, and IL-6 gene expression. In addition, NC8-pSIP409-pgsA'-MCP at different CFUs increased the survival of largemouth bass after LMBV infection; in particular, NC8-pSIP409-pgsA'-MCP (109 CFU) resulted in approximately 30% survival. NC8-pSIP409-pgsA'-MCP immunization alleviated the pathological changes in the liver and spleen, exerting a more advantageous protective effect. These data suggest that the recombinant L. plantarum strain NC8-pSIP409-pgsA'-MCP can increase the resistance of largemouth bass to LMBV infection and that this strain is a promising candidate oral vaccine for the prevention of LMBV infection.

NLRP3 Plays a Key Role in Antihelminth Immunity in the Enteral and Parenteral Stages of Trichinella spiralis-Infected Mice.

Trichinellosis is an important foodborne zoonosis, and no effective treatments are yet available. Nod-like receptor (NLR) plays a critical role in the host response against nematodes. Therefore, we aimed to explore the role of the NLRP3 inflammasome (NLRP3) during the adult, migrating, and encysted stages of Trichinella spiralis infection. The mice were treated with the specific NLRP3 inhibitor MCC950 after inoculation with T. spiralis. Then, the role that NLRP3 plays during T. spiralis infection of mice was evaluated using enzyme-linked immunosorbent assay (ELISA), Western blotting, flow cytometry, histopathological evaluation, bone marrow-derived macrophage (BMDM) stimulation, and immunofluorescence. The in vivo results showed that NLRP3 enhanced the Th1 immune response in the adult and migrating stages and weakened the Th2 immune response in the encysted stage. NLRP3 promoted the release of proinflammatory factors (interferon gamma [IFN-γ]) and suppressed the release of anti-inflammatory factors (interleukin 4 [IL-4]). Pathological changes were also improved in the absence of NLRP3 in mice during T. spiralis infection. Importantly, a significant reduction in adult worm burden and muscle larvae burden at 7 and 35 days postinfection was observed in mice treated with the specific NLRP3 inhibitor MCC950. In vitro, we first demonstrated that NLRP3 in macrophages can be activated by T. spiralis proteins and promotes IL-1ß and IL-18 release. This study revealed that NLRP3 is involved in the host response to T. spiralis infection and that targeted inhibition of NLRP3 enhanced the Th2 response and accelerated T. spiralis expulsion. These findings may help in the development of protocols for controlling trichinellosis.

The global prevalence of highly pathogenic avian influenza A (H5N8) infection in birds: A systematic review and meta-analysis.

The zoonotic pathogen avian influenza A H5N8 causes enormous economic losses in the poultry industry and poses a serious threat to the public health. Here, we report the first systematic review and meta-analysis of the worldwide prevalence of birds. We filtered 45 eligible articles from seven databases. A random-effects model was used to analyze the prevalence of H5N8 in birds. The pooled prevalence of H5N8 in birds was 1.6%. In the regions, Africa has the highest prevalence (8.0%). Based on the source, village (8.3%) was the highest. In the sample type, the highest prevalence was organs (79.7%). In seasons, the highest prevalence was autumn (28.1%). The largest prevalence in the sampling time was during 2019 or later (7.0%). Furthermore, geographical factors also were associated with the prevalence. Therefore, we recommend site-specific prevention and control tools for this strain in birds and enhance the surveillance to reduce the spread of H5N8.

Characterization and pathogenicity of the porcine epidemic diarrhea virus isolated in China.

Piglet diarrhea caused by the porcine epidemic diarrhea virus (PEDV) is a common problem on pig farms in China associated with high morbidity and mortality rates. In this study, three PEDV isolates were successfully detected after the fourth blind passage in Vero cells. The samples were obtained from infected piglet farms in Jilin (Changchun), and Shandong (Qingdao) Provinces of China and were designated as CH/CC-1/2018, CH/CC-2/2018, and CH/QD/2018. According to the analysis of the complete S protein gene sequence, the CH/CC-1/2018 and CH/CC-2/2018 were allocated to the G2b branch, while CH/QD/2018 was located in the G1a interval and was closer to the vaccine strain CV777. Successful detection and identification of the isolated strains were carried out using electron microscopy and indirect immunofluorescence. Meanwhile, animal challenge experiments and viral RNA copies determination were used to compare the pathogenicity. The results showed that CH/CC-1/2018 in Changchun was more pathogenic than CH/QD/2018 in Qingdao. In conclusion, the discovery of these new strains is conducive to the development of vaccines to prevent the pandemic of PEDV, especially that the CH/CC-1/2018, and CH/CC-2/2018 were not related to the classical vaccine strain CV777.

Lactobacillus rhamnosus GG Promotes Early B Lineage Development and IgA Production in the Lamina Propria in Piglets.

Gut microbes play an important role in the development of host B cells. It has been controversial whether GALT is the development site of B cells in pigs. By investigating the relationship between gut microbes and the development of B cells in the GALT of piglets, we found, to our knowledge for the first time, that early B cells exist in the gut lamina propria (LP) in pigs at different ages. We further used Lactobacillus rhamnosus GG (LGG) to treat piglets. The results showed that LGG promotes the development of the early B lineage, affects the composition of the Ig CDR3 repertoires of B cells, and promotes the production of IgA in the intestinal LP. Additionally, we found that the p40 protein derived from LGG can activate the EGFR/AKT and NF-κB signaling pathways, inducing porcine intestinal epithelial cells (IPEC-J2) to secrete a proliferation-inducing ligand (APRIL), which promotes IgA production in B cells. Finally, we identified ARF4 and DIF3 as candidates for p40 receptors on IPEC-J2 by GST pull-down, liquid chromatography-mass spectrometry/mass spectrometry analysis, and coimmunoprecipitation. In conclusion, LGG could promote early B cell differentiation and development in the intestinal LP in piglets and might contribute to promoting IgA production via secretion of p40, which interacts with the membrane receptors on IPEC-J2 and induces them to secrete APRIL. Our study will provide insight to aid in better utilization of probiotics to increase human health.

Transcriptomic insights into the immune response of the intestine to Aeromonas veronii infection in northern snakehead (Channa argus).

Intestinal inflammation is a protective response that is implicated in bacterial enteritis triggered by gastrointestinal infection. The immune mechanisms elicited in teleost against the infection of Aeromonas veronii are largely unknown. In this study, we performed a de novo northern snakehead (Channa argus) transcriptome assembly using Illumina sequencing platform. On this basis we performed a comparative transcriptomic analysis of northern snakehead intestine from A. veronii-challenge and phosphate buffer solution (PBS)-challenge fish, and 2076 genes were up-regulated and 1598 genes were down-regulated in the intestines infected with A. veronii. The Gene Ontology (GO) enrichment analysis indicated that the differentially expressed genes (DEGs) were enriched to 27, 21 and 20 GO terms in biological process, cellular component, and molecular function, respectively. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that 420 DEGs were involved in 194 pathways. Moreover, 33 DEGs were selected for quantitative real-time PCR analysis to validate the RNA-seq data. The results reflected the consistency of the expression levels between qRT-PCR and RNA-seq data. In addition, a time-course analysis of the mRNA expression of 33 immune-related genes further indicated that the intestinal inflammation to A. veronii infection simultaneously regulated gene expression alterations. The present study provides transcriptome data of the teleost intestine, allowing us to understand the mechanisms of intestinal inflammation triggered by bacterial pathogens. DATA AVAILABILITY STATEMENT: All data supporting the findings of this study are available within the article and Supplementary files. The RNA-seq raw sequence data are available in NCBI short read archive (SRA) database under accession number PRJNA615958.

BRD4 inhibition exerts anti-viral activity through DNA damage-dependent innate immune responses.

Chromatin dynamics regulated by epigenetic modification is crucial in genome stability and gene expression. Various epigenetic mechanisms have been identified in the pathogenesis of human diseases. Here, we examined the effects of ten epigenetic agents on pseudorabies virus (PRV) infection by using GFP-reporter assays. Inhibitors of bromodomain protein 4 (BRD4), which receives much more attention in cancer than viral infection, was found to exhibit substantial anti-viral activity against PRV as well as a range of DNA and RNA viruses. We further demonstrated that BRD4 inhibition boosted a robust innate immune response. BRD4 inhibition also de-compacted chromatin structure and induced the DNA damage response, thereby triggering the activation of cGAS-mediated innate immunity and increasing host resistance to viral infection both in vitro and in vivo. Mechanistically, the inhibitory effect of BRD4 inhibition on viral infection was mainly attributed to the attenuation of viral attachment. Our findings reveal a unique mechanism through which BRD4 inhibition restrains viral infection and points to its potent therapeutic value for viral infectious diseases.

African swine fever virus: A raised global upsurge and a continuous threaten to pig husbandry.

African swine fever (ASF) is a severe disease affecting pigs with high economic losses and endemicity in various parts of the world. So, it represents a serious threat to the global food safety. The disease was discovered in sub-Saharan Africa where still endemic, and first case was recorded in Kenya in 1921. It is now found all over the world; in Africa, Europe, Asia, and the Pacific it already affects more than 50 countries including Republic of Korea, China, Malaysia, Germany, Bhutan, and India. The P72 protein encoded by the B646L gene is the major protein that reveals high reactogenicity and antigenicity. While the P54 plays a significant role in virus pathogenesis especially cell apoptosis. Multiple virus proteins can suppress the apoptosis of the infected cell at an early stage. The disease spreads through contact with the diseased cases, contaminated fomites, and tick bites. Meanwhile, contaminated water sources might be an essential source of infection. The recovered animals have a significant role in disease persistence as silent carriers. Multiple factors might lead to the observed disease seasonality. Route of exposure, infectious dose, and herd immunity are the main determinants of disease severity and clinical signs. The several types of PCR are well-accepted standard tests for early diagnosis. Although commercial ELISAs were stipulated by OIE, it should be combined with some other virology inspections or serological assays. The ASFV-free countries should be protected against the virus entrance especially that all developed vaccines failed to provoke enough immunity status against the challenged virus. Moreover, it accelerates the speed of revealing clinical symptoms.

Dietary supplementation of probiotics fermented Chinese herbal medicine Sanguisorba officinalis cultures enhanced immune response and disease resistance of crucian carp (Carassius auratus) against Aeromonas hydrophila.

Aeromonas hydrophila, a Gram-negative bacterium, is one of the major pathogens causing bacterial sepsis in aquatic animals due to drug resistance and pathogenicity, which could cause high mortality and serious economic losses to the aquaculture. Sanguisorba officinalis (called DiYu in Chinese, DY) is well known as herbal medicine, which could inhibit the growth of pathogenic bacteria, hemostasis and regulate the immune response. Moreover, the active ingredients in DY could remarkably reduce drug resistance. In this study, we investigated the effects of probiotic fermentation cultures on A. hydrophila through in vitro and in vivo experiments. Three lactic acid bacteria, including Lactobacillus rhamnosus (LGG), Lactobacillus casei (LC) and Lactobacillus plantarum (LP), were selected to ferment the Chinese herbal medicine DY. The assays of antagonism showed that all three fermented cultures could influence the ability of A. hydrophila growth, among which L. rhamnosus fermented DY cultures appeared to be the strongest inhibitory effect. In addition, the biofilm determination revealed that L. rhamnosus fermented DY cultures could significantly inhibit the biofilm formation of A. hydrophila compared to the other groups. Furthermore, protease, lecithinase and urease activities were found in the three fermentation cultures. Three probiotics fermented DY cultures were orally administration with crucian carp to evaluate the growth performance, immunological parameters and pathogen resistance. The results showed that the three fermentation cultures could promote the growth performance of crucian carp, and the immunoglobulins, antioxidant-related enzymes and immune-related genes were significantly enhanced. Besides, the results showed that crucian carp received L. rhamnosus (60.87%), L. casei (56.09%) and L. plantarum (41.46%) fermented DY cultures had higher survival rates compared with the control group after infection with A. hydrophila. Meanwhile, the pathological tissue results revealed that the probiotic fermented cultures could largely improve the tissues damage caused by the pathogenic bacteria. In conclusion, this study proved that the fermentation cultures of three probiotics could effectively inhibit the growth of A. hydrophila, regulate the level of immune response and improve the survival rate against A. hydrophila in crucian carp. The present data suggest that probiotic fermented Sanguisorba officinalis act as a potential gut-targeted therapy regimens to protecting fish from pathogenic bacteria infection.

Trichinella spiralis infection ameliorates the severity of Citrobacter rodentium-induced experimental colitis in mice.

Trichinellosis is a food-borne zoonotic parasitic disease that causes serious harm to human health and the pig breeding industry. However, there are reports that Trichinella spiralis (T. spiralis) infection can treat autoimmune diseases, including enteritis and experimental autoimmune encephalitis (EAE). However, research on the mechanism of T. spiralis infection in infectious enteritis has not been fully elucidated. Therefore, this experiment used Citrobacter rodentium (C. rodentium) to induce colitis in mouse models and explored its underlying mechanisms. In this experiment, a total of 72 C57BL/6 mice were randomly divided into four groups. Experimental mice in the TS and TS + CR groups were orally inoculated with individual T. spiralis larvae. At 21 days postinfection (dpi) with T. spiralis, experimental animals in the CR and TS + CR groups were inoculated by orogastric gavage with C. rodentium. The control group received PBS only. The results indicated that the weight loss and macroscopic and microscopic colon damage of mice in the TS + CR group were significantly decreased compared with those observed in the CR group. The results of flow cytometry showed that the expression levels of IL-4, IL-10 and CD4+CD25+Foxp3+ Tregs were increased (P < 0.05), while the expression levels of IFN-γ, IL-12 and IL-17 were decreased in the spleens and MLNs of the TS + CR experimental mice compared with the colitis model mice. ELISA results revealed that the TS + CR group not only elicited a strong IgG1 response (P < 0.01) but also a low level of IgG2a response (P < 0.05) relative to the CR group. The above results demonstrated that prior exposure of mice to T. spiralis infection ameliorated the severity of C. rodentium-induced infectious colitis.

Bacillus subtilis BSH has a protective effect on Salmonella infection by regulating the intestinal flora structure in chickens.

Salmonellosis is a worldwide zoonotic disease that poses a serious threat to the reproduction of livestock and poultry and the health of young animals. Probiotics including Bacillus species, have received increasing attention as a substitute for antibiotics. In this study, chicks infected with Salmonella were fed feed supplemented with the BSH to observe the pathological changes in the liver, detect the number of viable bacteria in the liver and spleen, and record the death of the chicks. The results showed that BSH could reduce the pathological changes in the liver and the invasion of Salmonella into the liver and spleen of chicks. In addition, the survival rate of chicks in the BSH experimental group was 60%, while that in the infected control group was 26%, indicating that BSH had a protective effect on chicks infected with Salmonella. Finally, the fecal microflora of 9-day-old chicks was analyzed by 16S rRNA high-throughput sequencing. The results showed that Salmonella infection could cause intestinal flora changes, while BSH could alleviate this change. In addition, BSH also promoted the proliferation of Lactobacillus salivarius in the cecum of chick. This study emphasized that BSH has anti- Salmonella infection effects in chickens and can be used as a candidate microecological preparation strain.

Improved pathogenicity of H9N2 subtype of avian influenza virus induced by mutations occurred after serial adaptations in mice.

H9N2 subtype, a low pathogenic avian influenza virus, is emerging as a major causative agent circulating poultry workplaces across China and other Asian countries. Increasing case number of interspecies transmissions to mammals reported recently provoked a great concern about its risks inducing global pandemics. In an attempt to understand the underlying mechanism of how the H9N2 virus disrupts the interspecies segregation to transmit to mammals. A mutant H9N2 strain was obtained by passaging the wildtype H9N2 A/chicken/Hong Kong/G9/1997 eight times from lung to lung in BALB/c mice. Our finding revealed that mice manifested severe clinical symptoms including losses of body weight, pathological damages in pulmonary sites and all died within two weeks after infected with the mutated H9N2, whereas all mice survived upon infected with wildtype strain in comparison, which suggested increased pathogenicity of the mutant strain. In addition, mice showed enhanced levels of proinflammatory cytokines in sera, including IL-6, TNF-α and IL-1ß compared to those subjected to wildtype viral infections. Sequence analysis showed that five amino acid substitutions occurred at PB2627, HA87, HA234, NP387 and M156, and a deletion mutation happened in the M gene (M157). Of these mutations, PB2 E627K played key roles in modulating lethality in mice. Taken together, the mutant H9N2 strain obtained by serial passaging of its wildtype in mice significantly increased its virulence leading to death of mice, which might be associated the accumulated mutations occurred on its genome.

Expression profiling and bioinformatics analysis of exosomal long noncoding RNAs in patients with myasthenia gravis by RNA sequencing.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disease mediated by acetylcholine receptor antibodies. Exosomes were shown to be involved in the immune modulation and autoimmune diseases. However, the expression and function of exosomal long noncoding RNAs (lncRNAs) in MG are still unclear. METHODS: We conducted high-throughput sequencing to detect the lncRNA profiles of serum exosomes in 6 MG patients (2 grade I, 2 grade IIa, and 2 grade IIb) and 6 healthy controls (HC). Then, differentially expressed (DE) lncRNAs with the greatest difference between the MG and HC groups were selected for further quantitative real-time polymerase chain reaction (qRT-PCR) validation in additional 30 MG patients and 10 HC. The DE lncRNAs were used to construct the coding/noncoding network and perform enrichment analysis. RESULTS: We identified 378 significantly upregulated and 348 significantly downregulated lncRNAs in MG patients compared with HC. The top 5 lncRNAs (NR_104677.1, ENST00000583253.1, NR_046098.1, NR_022008.1, and ENST00000581362.1) were validated and shown to be significantly increased in the serum exosome of MG, and the expression level of NR_046098.1 significantly increased with the MG grading. Enrichment analysis showed that DE genes mainly participated in the basic biological regulation of MG and immune-related pathways, such as autoimmune thyroid disease pathway and T-cell receptor signaling pathway. A specific lncRNA-miRNA-mRNA regulatory network associated with the 5 lncRNAs, 14 MG-related miRNAs and 30 mRNAs was constructed. CONCLUSIONS: We conducted a comprehensive analysis of exosomal lncRNAs to reveal potential biomarkers for the MG diagnosis and severity assessment.

Immunological evaluation of invasive Lactobacillus plantarum co-expressing EtMIC2 and chicken interleukin-18 against Eimeria tenella.

Chicken coccidiosis is a protozoan parasitic disease that leads to considerable economic losses in the poultry industry. In this study, we used invasive Lactobacillus plantarum (L.P) expressing the FnBPA protein as a novel bacterial carrier for DNA delivery into epithelial cells to develop a live oral DNA vaccine. A fusion DNA vaccine co-expressing EtMIC2 and chicken IL-18 (chIL-18) was constructed and then delivered to the host by invasive L.P. Its efficacy against Eimeria tenella challenge was evaluated in chickens by examining the relative weight gain rate; caecal lesion score; OPG; anti-coccidial index (ACI); levels of EtMIC2 antibody, FnBPA, IL-4, IL-18, IFN-γ and SIgA; and proliferation ability and percentages of CD4+ and CD8+ splenocytes. The experimental results showed that chickens immunized with invasive L.P carrying the eukaryotic expression vector pValac-EtMIC2 (pValac-EtMIC2/pSIP409-FnBPA) had markedly improved immune protection against challenge compared with that of chickens immunized with non-invasive L.P (pValac-EtMIC2/pSIP409). However, invasive L.P co-expressing EtMIC2 with the chIL-18 vector exhibited the highest protection efficiency against E. tenella. These results indicate that invasive Lactobacillus-expressing FnBPA improved humoural and cellular immunity and enhanced resistance to E. tenella. The DNA vaccine delivered by invasive Lactobacillus provides a new concept and method for the prevention of E. tenella.

Ligand Substituent Effects on the Spin-Crossover Behaviors of Dinuclear Iron(II) Compounds.

Six analogue compounds with the general formula [Fe2( xL)5(NCS)4]· yMeOH ( x = o-Cl, y = 3 for compound 1; x = m-Cl, y = 5 for 2; x = p-Cl, y = 1 for 3; x = o-Me, y = 2 for 4; x = m-Me, y = 2 for 5; x = p-Me, y = 3 for 6; L = N-phenylmethylene-4-amino-1,2,4-triazole) were synthesized. The two Fe(II) ions are triply bridged by the triazole groups of three xL ligands and each Fe(II) is further capped with two NCS- groups and one more xL ligand. These compounds show regular patterns in their magnetic properties that depend on the positions the substituent groups (-Cl or -Me) ride, i.e., ortho-substituted compounds 1 and 4 undergo complete one-step spin crossover (SCO), while meta-substituted compounds 2 and 5 display incomplete one-step SCO with lower transition temperatures, and para-substituted compounds 3 and 6 are in the high-spin states in all temperature ranges. Structural analyses reveal that the molecular geometry and intermolecular interactions of these compounds, which should account for the differences in magnetic properties, are obviously depend on the positions of substituent groups (steric effect), despite them being electron-withdrawing chlorine or electron-donating methyl, whereas theoretical calculations confirm that the electronic effects of substituent groups exert no effect on the magnetic properties.

Evaluation of salinomycin isolated from Streptomyces albus JSY-2 against the ciliate, Ichthyophthirius multifiliis.

The present study was undertaken to investigate the antiparasitic activity of extracellular products of Streptomyces albus. Bioactivity-guided isolation of chloroform extracts affording a compound showing potent activity. The structure of the compound was elucidated as salinomycin (SAL) by EI-MS, 1H NMR and 13C NMR. In vitro test showed that SAL has potent anti-parasitic efficacy against theronts of Ichthyophthirius multifiliis with 10 min, 1, 2, 3 and 4 h (effective concentration) EC50 (95% confidence intervals) of 2.12 (2.22-2.02), 1.93 (1.98-1.88), 1.42 (1.47-1.37), 1.35 (1.41-1.31) and 1.11 (1.21-1.01) mg L-1. In vitro antiparasitic assays revealed that SAL could be 100% effective against I. multifiliis encysted tomonts at a concentration of 8.0 mg L-1. In vivo test demonstrated that the number of I. multifiliis trophonts on Erythroculter ilishaeformis treated with SAL was markedly lower than that of control group at 10 days after exposed to theronts (P < 0.05). In the control group, 80% mortality was observed owing to heavy I. multifiliis infection at 10 days. On the other hand, only 30.0% mortality was recorded in the group treated with 8.0 mg L-1 SAL. The median lethal dose (LD50) of SAL for E. ilishaeformis was 32.9 mg L-1.

Nitrogen-Doped Highly Photoluminescent Carbon Dots Derived from Citric Acid and Guanidine Carbonate.

A facile one-pot hydrothermal method for fabricating nitrogen-doped carbon dots (N-CDs) was developed by using citric acid as a carbon source and guanidine carbonate as a nitrogen and carbon source. X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectra indicated that the N-CDs were rich in elemental nitrogen. They had excellent stability in the presence of various salt concentrations and under UV irradiation. The N-CDs exhibited high quantum yields (52%), as well as down-conversion and up-conversion photoluminescence. The N-CD photoluminescence was quenched in the presence of Hg2+, while nearly no intensity changes were observed when in the presence of Na+, Mg2+, Mn2+, Zn2+, Ni2+, Cu2+, Ba2+, Cd2+ or Ca2+. The binding constant (KSV) and detection limit were also determined.

Monitoring the Spin States of Ferrous Ions by Fluorescence Spectroscopy in Spin-Crossover-Fluorescent Hybrid Materials.

The grafts of fluorophores 9-anthraldehyde (AD) and 9-phenanthrenecarboxaldehyde (PD), respectively, on the one-dimensional spin-crossover compound [Fe(L)3 ](ClO4 )2 (FeL, L=4-amino-1,2,4-triazole) by post-synthetic aldimine condensation reactions produced two spin-crossover (SCO)-fluorescent hybrid materials, that is, FeL-AD and FeL-PD. The spin-crossover critical temperatures of the two materials both centered at Tc ↓=254 and Tc ↑=256 K, whereas the fluorescence intensities of the two materials featured functions of the temperature that strictly synchronized with the spin-crossover processes, which showed that the ligand-centered fluorescence was dominated by the spin states of the ferrous ions. The bifunctional entities (spin-crossover centers and fluorophores) in FeL-AD or FeL-PD showed spectral band overlap that purported the Förster resonance energy transfer mechanism of such spin-crossover-fluorescence correlation. The post-synthetic modification of SCO materials and the relationship between the fluorescence and the SCO may be helpful in the development of multifunctional materials that can be sensitive to multiple stimuli.