Automatic classification of fetal heart rate based on a multi-scale LSTM network.

Introduction: Fetal heart rate monitoring during labor can aid healthcare professionals in identifying alterations in the heart rate pattern. However, discrepancies in guidelines and obstetrician expertise present challenges in interpreting fetal heart rate, including failure to acknowledge findings or misinterpretation. Artificial intelligence has the potential to support obstetricians in diagnosing abnormal fetal heart rates. Methods: Employ preprocessing techniques to mitigate the effects of missing signals and artifacts on the model, utilize data augmentation methods to address data imbalance. Introduce a multi-scale long short-term memory neural network trained with a variety of time-scale data for automatically classifying fetal heart rate. Carried out experimental on both single and multi-scale models. Results: The results indicate that multi-scale LSTM models outperform regular LSTM models in various performance metrics. Specifically, in the single models tested, the model with a sampling rate of 10 exhibited the highest classification accuracy. The model achieves an accuracy of 85.73%, a specificity of 85.32%, and a precision of 85.53% on CTU-UHB dataset. Furthermore, the area under the receiver operating curve of 0.918 suggests that our model demonstrates a high level of credibility. Discussion: Compared to previous research, our methodology exhibits superior performance across various evaluation metrics. By incorporating alternative sampling rates into the model, we observed improvements in all performance indicators, including ACC (85.73% vs. 83.28%), SP (85.32% vs. 82.47%), PR (85.53% vs. 82.84%), recall (86.13% vs. 84.09%), F1-score (85.79% vs. 83.42%), and AUC(0.9180 vs. 0.8667). The limitations of this research include the limited consideration of pregnant women's clinical characteristics and disregard the potential impact of varying gestational weeks.

Dynamic analysis of rabies transmission and elimination in mainland China.

Rabies is an acute zoonotic infectious disease caused by rabies virus. In 2015, the World Health Organization proposed the goal of eliminating dog-induced human rabies by 2030. In response to this goal positively, China has been dedicated to the control and elimination of rabies mainly caused by dogs, for nearly 10 years. By applying infectious disease dynamics, in this paper, we establish a dog-human rabies transmission model to forecast future epidemic trends of rabies, assess whether the goal of eliminating dog-induced human rabies cases in China can be achieved in 2030, and further evaluate and suggest the follow-up sustained preventive measures after the elimination of human rabies. By analyzing and simulating above dynamic model, it is concluded that rabies has been well controlled in China in recent years, but dog-induced human rabies cannot be eliminated by 2030 according to current situation. In addition, we propose to improve rabies control efforts by increasing the immunization coverage rate of rural domestic dogs, controlling the number of stray dogs and preventing the import of rabies virus in wild animals. Immunization coverage rate of rural domestic dogs which is currently less than 10% is far from requirement, and it needs to reach 50%-60% to meet the goal of 2030. Since it is difficult to immunize stray dogs, we suggest to control the number of stray dogs below 15.27 million to achieve the goal. If the goal of eliminating human rabies is reached in 2030, the essential immunization coverage needs to be maintained for 18 years to reduce the number of canine rabies cases to zero. Lastly, to prevent transmission of rabies virus from wild animals to dogs, the thresholds of the number of dogs and the immunization coverage rate of dogs after eliminating canine rabies cases are also discussed.

Probing surface properties of organic molecular layers by scanning tunneling microscopy.

In view of the relevance of organic thin layers in many fields, the fundamentals, growth mechanisms, and dynamics of thin organic layers, in particular thiol-based self-assembled monolayers (SAMs) on Au(111) are systematically elaborated. From both theoretical and practical perspectives, dynamical and structural features of the SAMs are of great intrigue. Scanning tunneling microscopy (STM) is a remarkably powerful technique employed in the characterization of SAMs. Numerous research examples of investigation about the structural and dynamical properties of SAMs using STM, sometimes combined with other techniques, are listed in the review. Advanced options to enhance the time resolution of STM are discussed. Additionally, we elaborate on the extremely diverse dynamics of various SAMs, such as phase transitions and structural changes at the molecular level. In brief, the current review is expected to supply a better understanding and novel insights regarding the dynamical events happening in organic SAMs and how to characterize these processes.

MRI for Diagnosing Intrauterine Adhesions.

OBJECTIVES: To prospectively assess the diagnostic accuracy of MRI and transvaginal ultrasound (TVS) as well as the prognostic value of MRI for intrauterine adhesions (IUAs), using hysteroscopy as the reference standard. DESIGN: Prospective observational study. SETTING: Tertiary medical centre. PATIENT(S): Ninety-two women with amenorrhea, hypomenorrhea, subfertility, or recurrent pregnancy loss who underwent MRI and in whom Asherman's syndrome was suspected upon TVS. INTERVENTION(S): MRI and TVS were conducted approximately 1 week before hysteroscopy. METHODS: Ninety-two patients suspected of having Asherman's syndrome were examined by MRI and TVS within 7 days of an upcoming hysteroscopy. All hysteroscopy procedures were performed during the early proliferative phase of the menstrual cycle. All hysteroscopic diagnoses were performed by an experienced expert. All MRIs were read by 2 experienced, blinded radiologists. RESULTS: MRI was highly accurate (94.57%), sensitive (98.8%), and specific (42.9%) for diagnosing IUAs with a positive predictive value of 95.5% and a negative predictive value of 75%. The diagnostic values of MRI and TVS were significantly different according to McNemar tests. Junctional zone signal and junctional zone alterations correlated with the stage of IUAs. CONCLUSION: MRI is markedly superior to TVS in terms of diagnostic accuracy for IUAs, with total agreement with hysteroscopic findings. However, the main advantage of MRI is that, unlike TVS and hysterosalpingography, it can be used to assess the risk of hysteroscopy and to predict postoperative recovery and future pregnancy based on the uterine junctional zone.

Genome-Wide Analysis of MYB Transcription Factors and Screening of MYBs Involved in the Red Color Formation in Rhododendron delavayi.

Flower color is one of the crucial traits of ornamental plants. Rhododendron delavayi Franch. is a famous ornamental plant species distributed in the mountain areas of Southwest China. This plant has red inflorescence and young branchlets. However, the molecular basis of the color formation of R. delavayi is unclear. In this study, 184 MYB genes were identified based on the released genome of R. delavayi. These genes included 78 1R-MYB, 101 R2R3-MYB, 4 3R-MYB, and 1 4R-MYB. The MYBs were divided into 35 subgroups using phylogenetic analysis of the MYBs of Arabidopsis thaliana. The members of the same subgroup in R. delavayi had similar conserved domains and motifs, gene structures, and promoter cis-acting elements, which indicate their relatively conserved function. In addition, transcriptome based on unique molecular identifier strategy and color difference of the spotted petals, unspotted petals, spotted throat, unspotted throat, and branchlet cortex were detected. Results showed significant differences in the expression levels of R2R3-MYB genes. Weighted co-expression network analysis between transcriptome and chromatic aberration values of five types of red samples showed that the MYBs were the most important TFs involved in the color formation, of which seven were R2R3-MYB, and three were 1R-MYB. Two R2R3-MYB (DUH019226.1 and DUH019400.1) had the highest connectivity in the whole regulation network, and they were identified as hub genes for red color formation. These two MYB hub genes provide references for the study of transcriptional regulation of the red color formation of R. delavayi.

Discovery of Elaphuri Davidiani Cornu-specific peptide biomarkers by peptidomics analysis-based method.

Elaphuri Davidiani Cornu (EDC) is the antler of the male Père David's deer, which has been reported to have multiple biological activities, and its use as a traditional Chinese medicine (TCM) in China has been known for thousands of years. However, EDC is difficult to distinguish from other related species-derived antlers in powder or extract form in TCM clinic use, such as Cervus elaphus Cornu (CEC) and Cervus nippon Cornu (CNC), both derived from Cervidae and easily confused with EDC. In this study, a strategy using peptidomics combined with mathematics set analysis was used to identify EDC-specific peptide biomarkers, and four specific peptide biomarkers (Pep-E1-E4) were identified and validated. Pep-E1, Pep-E3, and Pep-E4 could be exclusively detected in EDC samples, with relative peak areas of 0.298 ± 0.060, 0.039 ± 0.015, and 0.037 ± 0.008, whereas Pep-E2 showed relative peak area of 0.516 ± 0.101 in EDC, 0.132 ± 0.026 in CEC, and 0.136 ± 0.047 in CNC samples, respectively. These four peptides are applicable to distinguish EDC from CEC and CNC, which is of great significance for the quality control of EDC.

Genetic analysis and prenatal diagnosis of 76 Chinese families with X-linked adrenoleukodystrophy.

BACKGROUND: Variants in the ATP binding cassette protein subfamily D member 1 (ABCD1) gene are known to cause X-linked adrenoleukodystrophy (X-ALD). This study focused on the characteristics of ABCD1 variants in Chinese X-ALD families and elucidated the value of genetic approaches for X-ALD. METHODS: 68 male probands diagnosed as X-ALD were screened for ABCD1 variants by the Sanger sequencing of polymerase chain reaction (PCR) products and multiplex ligation-dependent probe amplification (MLPA) combined with long-range PCR. Prenatal diagnosis was performed in 20 foetuses of 17 probands' mothers. Descriptive statistics were used to summarise the gene variants and prenatal diagnosis characteristics and outcomes. RESULTS: This study allowed the identification of 61 variants occurring in 68 families, including 58 single nucleotide variants or small deletion/insertion variants and 3 large deletions. Three probands with no variants detected by next-generation sequencing were found to have variants by PCR-sequencing. Prenatal diagnosis found that 10 of the 20 foetuses had no variants in ABCD1. CONCLUSION: PCR primers that do not amplify the pseudogenes must be used for PCR-sequencing. MLPA combined with long-range PCR can detect large deletions and insertions, which are usually undetectable by PCR-sequencing. Prenatal diagnosis could help to prevent the birth of infants with X-ALD.

Mitochondrial DNA Copy Number in Rett Syndrome Caused by Methyl-CpG-Binding Protein-2 Variants.

OBJECTIVE: To determine changes in mitochondrial DNA (mtDNA) copy number in peripheral blood in Rett syndrome caused by methyl-CpG-binding protein-2 (MECP2) variants and explore the mechanism of mitochondrial dysfunction in Rett syndrome. STUDY DESIGN: Female patients who were diagnosed with Rett syndrome and had an MECP2 variant (n = 142) were recruited in this study, along with the same number of age- and sex-matched healthy controls. MtDNA copy number was quantified by real-time quantitative polymerase chain reaction with TaqMan probes. The differences in mtDNA copy number between the Rett syndrome group and the control group were analyzed using the independent-samples t test. Linear regression, biserial correlation analysis, and one-way ANOVA were applied for the correlations between mtDNA copy number and age, clinical severity, variant types, functional domains, and hot-spot variants. RESULTS: MtDNA copy number was found to be significantly increased in the patients with Rett syndrome with MECP2 gene variants compared with the control subjects. Age, clinical severity, variant types, functional domains, and hot-spot variants were not related to mtDNA copy number in patients with Rett syndrome. CONCLUSIONS: MtDNA copy number is increased significantly in patients with Rett syndrome, suggesting that changes in mitochondrial function in Rett syndrome trigger a compensatory increase in mtDNA copy number and providing new possibilities for treating Rett syndrome, such as mitochondria-targeted therapies.

Variation in Petal and Leaf Wax Deposition Affects Cuticular Transpiration in Cut Lily Flowers.

The vase life of cut flowers is largely affected by post-harvest water loss. Cuticular wax is the primary barrier to uncontrolled water loss for aerial plant organs. Studies on leaf cuticular transpiration have been widely conducted; however, little is known about cuticular transpiration in flowers. Here, the cuticular transpiration rate and wax composition of three lily cultivars were determined. The minimum water conductance of tepal cuticles was higher at the green bud than open flower stage. Lily cuticular transpiration exhibited cultivar- and organ-specific differences, where transpiration from the tepals was higher than leaves and was higher in the 'Huang Tianba' than 'Tiber' cultivar. The overall wax coverage of the tepals was higher compared to that of the leaves. Very-long-chain aliphatics were the main wax constituents and were dominated by n-alkanes with carbon (C) chain lengths of C27 and C29, and C29 and C31 in the tepal and leaf waxes, respectively. Primary alcohols and fatty acids as well as small amounts of alkyl esters, ketones, and branched or unsaturated n-alkanes were also detected in both tepal and leaf waxes, depending on the cultivar and organ. In addition, the chain-length distributions were similar between compound classes within cultivars, whereas the predominant C-chain lengths were substantially different between organs. This suggests that the less effective transpiration barrier provided by the tepal waxes may result from the shorter C-chain aliphatics in the tepal cuticle, compared to those in the leaf cuticle. These findings provide further insights to support the exploration of potential techniques for extending the shelf life of cut flowers based on cuticular transpiration barrier properties.

[Textual and information research of classical prescription Mijiao Pills].

Elaphurus davidianus( Milu),a rare animal unique to China,has been used as medicine for more than a thousand years,but the extinction of Milu in modern times resulted in the unavailability of related medical products. Today,the reintroduction of Milu population makes it possible to restore its medicinal usage. The resource reserves of Cervi Cornu,the natural shedding product from Milu,are increasing with the expansion of the population,allowing it to be fully utilized in the medical field. Mijiao Pills,first recorded in Important Prescriptions Worth a Thousand Gold for Emergency( Bei Ji Qian Jin Yao Fang) by Sun Simiao in the Tang Dynasty,is the first Chinese medicinal prescription with Cervi Cornu as the sovereign medicinal,which is effective in tonifying. Its composition,preparation,efficacy and indications,and administration are described in detail in the Important Prescriptions Worth a Thousand Gold for Emergency,which however,have changed significantly over the thousands of years,seriously affecting the clinical application of this classical prescription and related product development. Therefore,the key information of this prescription should be systematically collated and summarized. According to the principles of textual research on key information in ancient classical prescriptions promulgated by relevant authorities,this paper reviewed ancient Chinese medical books of the past dynasties,modern literature,as well as the Pharmacopoeia of the People's Republic of China( 2020 Version) to figure out such key information as the source,historical evolution,original plants and animals and their processing,dosage,preparation,and usage of Mijiao Pills. This paper aimed to provide a basis for the clinical application of Mijiao Pills and subsequent product development,thus facilitating the development and utilization of this precious medicinal animal resource.

[Regional differences of nucleosides and amino acids in Elaphuri Davidiani Cornu].

In order to reveal the regional characteristics of nucleosides and amino acids in Elaphuri Davidiani Cornu,39 samples of Elaphuri Davidiani Cornu collected from 4 different regions were analyzed by UPLC-QTRAP ~®/MS2 method followed by orthogonal partial least-squares discrimination analysis( OPLS-DA) and cluster analysis( CA). The results showed all the samples contained abundant nucleosides and amino acids,with the total content of 45. 09 µg·g~(-1) and 634. 80 µg·g-1,respectively. The samples presented significant regional differences in the contents of individual components,and the main differential components included Ura,Hpro,Thr,Glu,G5 P,2'-dG,Adeno,Met,Ade,Gln,Orni,Phe,2'-dA,Hit,Lys,and Ile. Among them,Ura,Met,Glu,and Ile had the highest content in the samples from Dafeng in Jiangsu,Qinhu in Jiangsu,Beijing,and Shishou in Hubei,respectively. OPLS-DA and CA demonstrated that all the samples of Elaphuri Davidiani Cornu could be divided into three categories,reflecting the regional characteristics. The results indicated that the accumulation of nucleosides and amino acids in Elaphuri Davidiani Cornu was closely related to its habitat,providing a useful reference for the research on the quality formation,quality evaluation and control,as well as the comprehensive utilization of Elaphuri Davidiani Cornu. The findings suggested that the content factors of Ura,Met,Glu,and Ile could be included into the quality standard system of Elaphuri Davidiani Cornu as the characteristics of medicinal materials from different regions.

Hemopexin as an acute phase protein regulates the inflammatory response against bacterial infection of Nile tilapia (Oreochromis niloticus).

Hemopexin, a high affinity heme-binding protein is widely involved in variety physiological and pathological processes. It is an important acute phase response protein, and is important in regulating the inflammatory response. In this study, the open reading frame of Nile tilapia hemopexin (OnHpx) gene was amplified. The expression pattern of OnHpx in natural and bacterial challenged tilapia tissues were analyzed through RT-qPCR. The results indicated the OnHpx was most abundant in liver, and increased significantly in liver, spleen, head kidney and peripheral blood after bacterial challenge. Furthermore, the OnHpx mRNA was also significantly up-regulated in monocytes/macrophages and hepatocytes under the stimulation of S. agalactiae or A. hydrophila. In addition, the recombinant OnHpx protein could effectively reduce the bacteria proliferation and alleviate the inflammatory reaction caused by bacteria. Moreover, the (r)OnHpx also regulated the respiratory burst of monocytes/macrophages and played an important role in the antioxidant process. To our knowledge, these results provide the first evidence on the antibacterial and anti-inflammatory response mechanism of Hpx in early vertebrates. This brings new insights about the understanding of the evolutionary origins and ancient roles of the Hpx in the innate immune defense.

Prediction of repeated-dose intravenous ketamine response in major depressive disorder using the GWAS-based machine learning approach.

Major depressive disorder (MDD) is one of the most common psychiatric disorders. Various clinical studies have shown that the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine has rapid, robust, and sustained antidepressant effects. However, given the concerns about the adverse effects of ketamine on patients, it would be important to identify a set of biomarkers that could be used to predict clinical outcomes for its treatment. A total of 83 MDD patients received treatment with six ketamine infusions for up to 2 weeks and were classified into "responders" or "non-responders" based on an average change in the HAMD score >50% from baseline. A nested cross-validation approach was applied to prevent information leakage and overestimation of model performance. The initial dataset was divided randomly into training and test sets in a nested six-fold cross-validation. We first performed genome-wide logistic regression to find potentially significant variants related to treatment response and then selected the top SNPs based on the genetic association results using the random forests algorithm. Subsequently, six machine learning models were employed to construct prediction models by using ten-fold cross-validation. A series of model comparisons showed that the best performing fold was characterized by accuracy of 0.85, precision of 0.75, and a sensitivity of 1.00 with the support vector machine algorithm. Together, these findings demonstrated that the machine learning approach can predict the treatment outcomes of multiple ketamine infusions on the basis of the genotyping information of each participant.

Autonomous apomixis in Praxelis clematidea (Asteraceae: Eupatorieae), an invasive alien plant.

Understanding the reproductive mechanisms of invasive alien species can lay the foundation for effective control measures. Praxelis clematidea is a triploid neotropical Asteraceae species that is invasive in China and other countries. However, few studies have focused on its reproductive biology. In this study, flow cytometric seed screening (FCSS) was used to identify and confirm the reproductive mode of the species. The development of ovules, anthers, and mega- and microgametophytes was observed using a clearing method and differential interference contrast microscopy. Pollen viability was measured using the Benzidine test and Alexander's stain. Pollen morphology was observed via fluorescence microscopy after sectioning the disk florets and staining with water-soluble aniline blue or 4'6-diamidino-2-phenylindole nuclei dyes. Controlled pollination experiments were conducted on four populations in China to examine the breeding system and to confirm autonomous apomixis. The reproductive mode was found to be autonomous apomixis without pseudogamy, according to FCSS. Megaspore mother cells developed directly into eight-nucleate megagametophytes without meiosis, conforming to Antennaria-type diplospory. The unreduced egg cells developed into embryos through parthenogenesis, while the endosperm was formed by the fusion of two unreduced polar nuclei. Pollen viability was very low (0.82 ± 0.57 % and 0.36 ± 0.44 %) as measured by the Benzidine test and Alexander's stain, respectively. The majority of the pollen grains were empty and had neither cytoplasm nor nuclei. The seed set was >90 % for all treatments of open pollination, bagging and emasculated capitula. Mature cypselae developed in capitula that were emasculated before flowering, which confirmed that the breeding system of P. clematidea was autonomous apomixis. The present study is the first report of autonomous apomixis in P. clematidea in China. Antennaria-type autonomous apomixis in P. clematidea greatly increases the probability of successful colonisation and dispersal of P. clematidea into new areas, which likely contributes to its high invasion potential. Effective control measures should be implemented to prevent autonomous (pollen-independent) seed production.

Mannose-Binding Lectin Possesses Agglutination Activity and Promotes Opsonophagocytosis of Macrophages with Calreticulin Interaction in an Early Vertebrate.

The innate immune system is an ancient defense system in the process of biological evolution, which can quickly and efficiently resist pathogen infection. In mammals, mannose-binding lectin (MBL) is a key molecule in the innate immune and plays an essential role in the first line of host defense against pathogenic bacteria. However, the evolutionary origins and ancient roles of immune defense of MBL and its mechanism in clearance of microbial pathogens are still unclear, especially in early vertebrates. In this study, Oreochromis niloticus MBL (OnMBL) was successfully isolated and purified from the serum of Nile tilapia (O. niloticus). The OnMBL was able to bind and agglutinate with two important pathogens of tilapia, Streptococcus agalactiae and Aeromonas hydrophila Interestingly, the OnMBL was able to significantly inhibit the proliferation of pathogenic bacteria and reduce the inflammatory response. Upon bacterial challenge, the downregulation of OnMBL expression by RNA interference could lead to rapid proliferation of the pathogenic bacteria, ultimately resulting in tilapia death. However, the phenotype was rescued by reinjection of the OnMBL, which restored the healthy status of the knockdown tilapia. Moreover, a mechanistic analysis revealed that the OnMBL could clear pathogenic bacteria by collaborating with cell-surface calreticulin to facilitate phagocytosis in a complement activation-independent manner. To our knowledge, these results provide the first evidence on the antibacterial response mechanism of MBL performing evolutionary conserved function to promote opsonophagocytosis of macrophages in early vertebrates and reveals new insights into the understanding of the evolutionary origins and ancient roles basis of the C-type lectins in the innate immune defense.

Relative content detection of oligomannose modification of IgM heavy chain induced by TNP-antigen in an early vertebrate through nanoLC-MS/MS.

N-glycan modification is reported to be important in regulating the structure and function of immunoglobulins in mammals. While, the study on teleost immunoglobulin glycosylation is still limitted. In this study, we constructed a TNP-antigen driven model, and detected the site-specific N-glycans of PBS-immunized and TNP-specific Oreochromis niloticus serum IgM through 18O-labeling and nanoLC-MS/MS. These methods are widely used for peptide enrichment and protein modification identification, but rarely used in detecting the level of N-glycosylation in teleost Igs that driven by specific antigen. The results revealed that there are four N-glycosylation sites in O.niloticus IgM heavy chain, namely, the Asn-315 site in the CH2 domain, the Asn-338 site in the CH3 domain, and the Asn-509 and Asn-551 sites in the CH4 domain, All of the four residues were efficiently N-glycosylated. After immunized with TNP-antigen, the signal strength of oligomannose in the TNP-specific IgM in primary mass spectrometry was significantly higher than that in the PBS-immunized IgM. Notably, the TNP-specific IgM had an Asn-509 site fully occupied with oligomannose, while only a small amount of oligomannose was found in the PBS-immunized IgM of this site. N-glycans in other sites were mainly complex-type with a low content of fucosylation and sialylated. The oligomannose in TNP-specific IgM was further verified to be essential for the binding of IgM and MBL. These results demonstrated that the TNP-antigen induced the site-specific oligomannose modification of O.niloticus IgM heavy chain, and played an important role in the interaction of IgM and MBL, which provided insights into the evolutionary understanding of the IgM oligomannose modification and function.

MAp34 Regulates the Non-specific Cell Immunity of Monocytes/Macrophages and Inhibits the Lectin Pathway of Complement Activation in a Teleost Fish.

The lectin pathway of the complement system is one of the main components of innate immunity, which plays a pivotal role in the defense against infectious microorganisms and maintains immune homeostasis. However, its control mechanisms remain unclear in teleost fish. In this study, we described the identification and functional characterization of a mannose-binding lectin associated protein MAp34 (OnMAp34) from Nile tilapia (Oreochromis niloticus) at molecular, cellular, and protein levels. The open reading frame (ORF) of OnMAp34 is 918 bp of nucleotide sequence encoding a polypeptide of 305 amino acids. The deduced amino acid sequence has three characteristic structures, including two C1r/C1s-Uegf-BMP domains (CUB) and one epidermal growth factor domain (EGF). Expression analysis revealed that the OnMAp34 was highly expressed in the liver and widely existed in other examined tissues. In addition, the mRNA and protein expression levels of OnMAp34 were remarkably altered upon infection with Streptococcus agalactiae and Aeromonas hydrophila in vivo and in vitro. Further, we found that the OnMAp34 could participate in the non-specific cellular immune defense, including the regulation of inflammation, migration, and enhancement of phagocytosis of monocytes/macrophages. Moreover, the OnMAp34 could compete with OnMASPs to combine OnMBL and inhibit the lectin pathway of complement activation. Overall, our results provide new insights into the understanding of MAp34 as a potent regulator in the lectin complement pathway and non-specific cell immunity in an early vertebrate.

A microfibril-associated glycoprotein 4 (MFAP4) from Nile tilapia (Oreochromis niloticus) possesses agglutination and opsonization ability to bacterial pathogens.

Microfibril-associated glycoprotein 4 (MFAP4), a pattern recognition-like molecule with a fibrinogen-like domain (FBG), has the ability to combine and agglutinate pathogens, playing an essential role in the first line of innate immune defense. In this study, the sequence of Nile tilapia (Oreochromis niloticus) microfibril-associated glycoprotein 4 (OnMFAP4) open reading frame (ORF) was amplified and identified. The ORF of OnMFAP4 is 720 bp of nucleotides and codes for 239 amino acids. Spatial mRNA encoding analysis indicated that OnMFAP4 was highly produced in liver, intestine and head kidney in healthy tilapia, and with the lowest expression in muscle. After challenges with Streptococcus agalactiae (S. agalactiae) and Aeromonas hydrophila (A. hydrophila), the expression of OnMFAP4 mRNA was prominently produced in the liver, spleen and head kidney. The up-regulation of OnMFAP4 expression was also presented in head kidney monocytes/macrophages (MO/MΦ) and hepatocytes. Recombinant OnMFAP4 ((r)OnMFAP4) could bind and agglutinate both bacterial pathogens. Moreover, (r)OnMFAP4 could take part in the modulation of inflammation and phagocytosis. In conclusion, this study revealed that OnMFAP4 might take effect in host defense against bacterial infection in Nile tilapia, with agglutination and opsonization capability to bacterial pathogens.

Expression and functional analysis of Nile tilapia transferrin receptors (TfRs) in host resistance to pathogenic bacteria and iron ion metabolism.

Transferrin receptors (TfRs) play an essential role in iron-withholding strategy, and are involved in immune response against bacterial infection. In this study, the transferrin receptor 1 (OnTfR1) and transferrin receptor 2 (OnTfR2) genes are identified and characterized in Nile tilapia (Oreochromis niloticus). The open reading frames of OnTfR1 and OnTfR2 are 2220 and 2343 bp of nucleotide sequence, encoding 739 and 780 amino acids, respectively. The deduced proteins of OnTfR1 and OnTfR2 are highly homologous to those of other species, containing three conserved TfR superfamily domains (PA TfR domain, M28 TfR domain and TfR dimer domain). Expression analyses of OnTfRs in the healthy tilapia reveal that the OnTfR1 and OnTfR2 transcripts are the most abundant in the liver. The in vivo studies show that the expressions of OnTfRs are significantly up-regulate in liver and spleen, following infections of Streptococcus agalactiae and Aeromonas hydrophila. In addition, the in vitro studies reveal that the up-regulations of OnTfR expressions are also significant in monocytes/macrophages and hepatocytes upon the stimulations of S. agalactiae and A. hydrophila. Moreover, the iron ion (Fe3+) could significantly increase the expressions of OnTfRs in monocytes/macrophages and hepatocytes. Taken together, the present study indicates that OnTfRs may be involved in host defense against bacterial infection and possess the function of combining or transporting iron ions in Nile tilapia.