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Unsupervised Domain Adaptation (UDA) is quite challenging due to the large distribution discrepancy between the source domain and the target domain. Inspired by diffusion models which have strong capability to gradually convert data distributions across a large gap, we consider to explore the diffusion technique to handle the challenging UDA task. However, using diffusion models to convert data distribution across different domains is a non-trivial problem as the standard diffusion models generally perform conversion from the Gaussian distribution instead of from a specific domain distribution. Besides, during the conversion, the semantics of the source-domain data needs to be preserved to classify correctly in the target domain. To tackle these problems, we propose a novel Domain-Adaptive Diffusion (DAD) module accompanied by a Mutual Learning Strategy (MLS), which can gradually convert data distribution from the source domain to the target domain while enabling the classification model to learn along the domain transition process. Consequently, our method successfully eases the challenge of UDA by decomposing the large domain gap into small ones and gradually enhancing the capacity of classification model to finally adapt to the target domain. Our method outperforms the current state-of-the-arts by a large margin on three widely used UDA datasets.
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Introduction: Chronic schizophrenia has a course of 5 years or more and has a widespread abnormalities in brain functional connectivity. This study aimed to find characteristic functional and structural changes in a long illness duration chronic schizophrenia (10 years or more). Methods: Thirty-six patients with a long illness duration chronic schizophrenia and 38 healthy controls were analyzed by independent component analysis of brain network functional connectivity. Correlation analysis with clinical duration was performed on six resting state networks: auditory network, default mode network, dorsal attention network, fronto-parietal network, somatomotor network, and visual network. Results: The differences in the resting state network between the two groups revealed that patients exhibited enhanced inter-network connections between default mode network and multiple brain networks, while the inter-network connections between somatomotor network, default mode network and visual network were reduced. In patients, functional connectivity of Cuneus_L was negatively correlated with illness duration. Furthermore, receiver operating characteristic curve of functional connectivity showed that changes in Thalamus_L, Rectus_L, Frontal_Mid_R, and Cerebelum_9_L may indicate a longer illness duration chronic schizophrenia. Discussion: In our study, we also confirmed that the course of disease is significantly associated with specific brain regions, and the changes in specific brain regions may indicate that chronic schizophrenia has a course of 10 years or more.
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Aiming at the problem that traditional wireless sensor networks produce errors in the positioning and tracking of motorised targets due to noise interference, this paper proposes a motorised target tracking method with a convolutional bi-directional long and short-term memory neural network and extended Kalman filtering, which is trained by using the simulated RSSI value and the actual target value of motorised targets collected from the convolutional bi-directional neural network to the sensor anchor node, so as to obtain a more accurate initial value of the manoeuvre target, and at the same time, the extended Kalman filtering method is used to accurately locate and track the real-time target, so as to obtain the accurate positioning and tracking information of the real-time target. Through experimental simulation, it can be seen that the algorithm proposed in this paper has good tracking effect in both linear manoeuvre target tracking scenarios and non-linear manoeuvre target tracking scenarios.
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CRISPR/Cas-mediated knock-in of DNA sequences enables precise genome engineering for research and therapeutic applications. However, designing effective guide RNAs (gRNAs) and homology-directed repair (HDR) donors remains a bottleneck. Here, we present protoSpaceJAM, an open-source algorithm to automate and optimize gRNA and HDR donor design for CRISPR/Cas insertional knock-in experiments, currently supporting SpCas9, SpCas9-VQR and enAsCas12a Cas enzymes. protoSpaceJAM utilizes biological rules to rank gRNAs based on specificity, distance to insertion site, and position relative to regulatory regions. protoSpaceJAM can introduce 'recoding' mutations (silent mutations and mutations in non-coding sequences) in HDR donors to prevent re-cutting and increase knock-in efficiency. Users can customize parameters and design double-stranded or single-stranded donors. We validated protoSpaceJAM's design rules by demonstrating increased knock-in efficiency with recoding mutations and optimal strand selection for single-stranded donors. An additional module enables the design of genotyping primers for deep sequencing of edited alleles. Overall, protoSpaceJAM streamlines and optimizes CRISPR knock-in experimental design in a flexible and modular manner to benefit diverse research and therapeutic applications. protoSpaceJAM is available open-source as an interactive web tool at protospacejam.czbiohub.org or as a standalone Python package at github.com/czbiohub-sf/protoSpaceJAM.
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Sistemas CRISPR-Cas , Técnicas de Introdução de Genes , RNA Guia de Sistemas CRISPR-Cas , Software , Técnicas de Introdução de Genes/métodos , RNA Guia de Sistemas CRISPR-Cas/genética , Humanos , Algoritmos , Internet , Edição de Genes/métodos , Reparo de DNA por Recombinação , Mutação , Mutagênese InsercionalRESUMO
The metabolism of long-chain polyunsaturated fatty acids (LCPUFAs) is closely associated with the risk and progression of colorectal cancer (CRC). This paper aims to investigate the role of LCPUFA in the crosstalk between intestinal microflora and macrophages, as well as the effects of these three parties on the progression of CRC. The metabolism and function of LCPUFA play important roles in regulating the composition of the human gut microflora and participating in the regulation of inflammation, ultimately affecting macrophage function and polarization, which is crucial in the tumor microenvironment. The effects of LCPUFA on cellular interactions between the two species can ultimately influence the progression of CRC. In this review, we explore the molecular mechanisms and clinical applications of LCPUFA in the interactions between intestinal microflora and intestinal macrophages, as well as its significance for CRC progression. Furthermore, we reveal the role of LCPUFA in the construction of the CRC microenvironment and explore the key nodes of the interactions between intestinal flora and intestinal macrophages in the environment. It provides potential targets for the metabolic diagnosis and treatment of CRC.
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Iron, copper, and zinc play integral roles in the battle against Mycobacterium tuberculosis (Mtb) infection; however, they are often trapped between nutrients and toxins, posing a significant challenge to macrophages and Mtb to utilize them. Due to this two-sided effect, macrophages and Mtb strictly regulate metal uptake, storage, and excretion. This review discusses the balanced regulation of iron, copper, and zinc in macrophages and Mtb during infection, focusing on the intracellular metal regulatory system. Macrophages typically use the two-sided effect of metals to limit Mtb access to nutrients or poison them. Mtb has developed a metal metabolism regulatory mechanism compatible with the nutritional immune strategy. This includes the mediation of relevant metalloproteins and metalloenzymes to maintain the multimetal balance. This review also explored the regulation of metal metabolism homeostasis in macrophages resistant to Mtb infection, providing a theoretical foundation for identifying potential clinical targets for Mtb infection, developing metalloid anti-tuberculosis drugs, and understanding the immune mechanisms against intracellular Mtb infection.
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Anopheles gambiae and its sibling species Anopheles coluzzii are the most efficient vectors of the malaria parasite Plasmodium falciparum. When females of these species feed on an infected human host, oogenesis and parasite development proceed concurrently, but interactions between these processes are not fully understood. Using multiple natural P. falciparum isolates from Burkina Faso, we show that in both vectors, impairing steroid hormone signaling to disrupt oogenesis leads to accelerated oocyst growth and in a manner that appears to depend on both parasite and mosquito genotype. Consistently, we find that egg numbers are negatively linked to oocyst size, a metric for the rate of oocyst development. Oocyst growth rates are also strongly accelerated in females that are in a pre-gravid state, i.e. that fail to develop eggs after an initial blood meal. Overall, these findings advance our understanding of mosquito-parasite interactions that influence P. falciparum development in malaria-endemic regions.
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Anopheles , Malária Falciparum , Malária , Animais , Feminino , Humanos , Plasmodium falciparum , Anopheles/parasitologia , Mosquitos Vetores , Interações Hospedeiro-Parasita , Malária Falciparum/parasitologia , Malária/parasitologia , OocistosRESUMO
We propose a weakly supervised approach for salient object detection from multi-modal RGB-D data. Our approach only relies on labels from scribbles, which are much easier to annotate, compared with dense labels used in conventional fully supervised setting. In contrast to existing methods that employ supervision signals on the output space, our design regularizes the intermediate latent space to enhance discrimination between salient and non-salient objects. We further introduce a contour detection branch to implicitly constrain the semantic boundaries and achieve precise edges of detected salient objects. To enhance the long-range dependencies among local features, we introduce a Cross-Padding Attention Block (CPAB). Extensive experiments on seven benchmark datasets demonstrate that our method not only outperforms existing weakly supervised methods, but is also on par with several fully-supervised state-of-the-art models. Code is available at https://github.com/leolyj/DHFR-SOD.
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Analysis of genetic markers can provide clues for case investigation. Short tandem repeat (STR) detection and analysis are widely used for both personal identification and parentage testing. However, DNA analysis currently cannot provide sufficient information for body fluid identification. Tissue or cell sources of samples can be identified by detecting body fluid-specific mRNA markers, which have been studied thoroughly. Integrating STR profiling and mRNA expression patterns can provide more information than conventional methods for investigations and the reconstruction of crime scenes; this can be achieved by DNA/RNA co-extraction technology, which is economical, efficient, and suitable for low-template samples. Here, we propose a co-analysis system based on the PowerPlex 16 kit. This system can simultaneously amplify 25 markers, including 15 STRs, one non-STR amelogenin, and nine mRNA markers (three blood-specific, two saliva-specific, two semen-specific, and two housekeeping gene markers). The specificity and sensitivity of the co-analysis system were determined and aged and degraded samples were used to validate the stability of the co-analysis system. Finally, different DNA/RNA ratios and various carriers were evaluated. The results showed that the DNA/RNA co-analysis system correctly identified different types of body fluid stains. The STR profiles obtained using the co-analysis system were identical to those obtained using the PP16 kit, which demonstrates that the mRNA primers used did not affect STR profiling. Complete STR and mRNA profiles could be obtained from 1/8 portions of buccal swabs, 1/16 portions of swabs of blood and semen samples, 0.1 cm2 of blood samples, 0.25 cm2 of semen samples, and 1.0 cm2 saliva samples. Additionally, our findings indicate that complete STR and mRNA profiles can be obtained with this system from blood and semen samples when the DNA/RNA ratio is 1:1/32. This study suggests that the co-analysis system could be used for simultaneous personal identification and body fluid identification.
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Líquidos Corporais , Impressões Digitais de DNA , Idoso , Amelogenina/genética , Líquidos Corporais/química , DNA/análise , Impressões Digitais de DNA/métodos , Marcadores Genéticos , Humanos , Repetições de Microssatélites , RNA/análise , RNA Mensageiro/análise , Saliva/química , Sêmen/químicaRESUMO
Insects, unlike vertebrates, are widely believed to lack male-biased sex steroid hormones1. In the malaria mosquito Anopheles gambiae, the ecdysteroid 20-hydroxyecdysone (20E) appears to have evolved to both control egg development when synthesized by females2 and to induce mating refractoriness when sexually transferred by males3. Because egg development and mating are essential reproductive traits, understanding how Anopheles females integrate these hormonal signals can spur the design of new malaria control programs. Here we reveal that these reproductive functions are regulated by distinct sex steroids through a sophisticated network of ecdysteroid-activating/inactivating enzymes. We identify a male-specific oxidized ecdysteroid, 3-dehydro-20E (3D20E), which safeguards paternity by turning off female sexual receptivity following its sexual transfer and activation by dephosphorylation. Notably, 3D20E transfer also induces expression of a reproductive gene that preserves egg development during Plasmodium infection, ensuring fitness of infected females. Female-derived 20E does not trigger sexual refractoriness but instead licenses oviposition in mated individuals once a 20E-inhibiting kinase is repressed. Identifying this male-specific insect steroid hormone and its roles in regulating female sexual receptivity, fertility and interactions with Plasmodium parasites suggests the possibility for reducing the reproductive success of malaria-transmitting mosquitoes.
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Anopheles , Ecdisteroides , Malária , Comportamento Sexual Animal , Animais , Anopheles/enzimologia , Anopheles/parasitologia , Anopheles/fisiologia , Ecdisteroides/biossíntese , Ecdisteroides/metabolismo , Feminino , Fertilidade , Humanos , Malária/parasitologia , Malária/prevenção & controle , Malária/transmissão , Masculino , Mosquitos Vetores/parasitologia , Oviposição , Fosforilação , PlasmodiumRESUMO
Duck adenovirus 3 (DuAdV-3; strain HB) was isolated and sequenced. The genome of the Muscovy-duck-origin virus contains a 54-bp insertion in pVIII, a 3-bp deletion in the overlap region of 100K, 22K, and 33K, a 42-bp deletion at the junction of ORF64 and ORF67, and a 715-bp deletion in right noncoding region of the genome. Notably, HB has a strikingly shorter right inverted terminal repeat (ITR) of 50 bp, whereas all other DuAdV-3 isolates have a 721-bp ITR. These findings demonstrate that HB is an insertion and deletion mutant of DuAdV-3.
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Aviadenovirus , Patos , Adenoviridae/genética , Animais , Aviadenovirus/genética , Sequência de Bases , Sequências Repetidas TerminaisRESUMO
Providing access to diverse polymer structures is highly desirable, which helps to explore new polymer materials. Poly(thioester sulfonamide)s, combining both the advantages of thioesters and amides, however, are rarely available in polymer chemistry. Here, the ring-opening copolymerization (ROCOP) of cyclic thioanhydride with N-sulfonyl aziridine using mild phosphazene base, resulting in well-defined poly(thioester sulfonamide)s with highly alternative structures, high yields, and controlled molecular weights, is reported. Additionally, benefiting from the mild catalytic process, this ROCOP can be combined with ROCOP of N-sulfonyl aziridines with cyclic anhydrides to produce novel block copolymers.
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Aziridinas , Aziridinas/química , Polimerização , Polímeros , Sulfonamidas/químicaRESUMO
BACKGROUND: Fatty acid composition and content affect rapeseed oil quality. Fatty acid synthesis-related genes in rapeseed have been studied globally by researchers. Nevertheless, rapeseed oil is mainly composed of seven different fatty acids (FA), and each fatty acid was regulated by different genes. Furthermore, different FA affect each other, which needs continuous and in-depth research to obtain more clear results in Brassica napus. RESULTS: In this paper, broad-scale miRNA expression profiles were constructed and 21 differentially expressed miRNAs were detected. GO enrichment analysis showed that most up-regulated proteins were involved in transcription factor activity and catalytic activity. KEGG pathway enrichment analysis indicated that 20 pathways involving 36 target genes were enriched, of which the bna00592 pathway may be involved in fatty acid metabolism. The results were verified using a quantitative real-time PCR (RT-qPCR) analysis, we found that the target gene of bna-miR156b > c > g was the OPR (12-oxo-phytodienoic acid reductase). Four copies of OPR gene were found, and the over-expression vectors (pCAMBIA1300-35 s-OPR and pCAMBIA1300-RNAi-OPR) were constructed to verify their functions. In T1 and T2 generation, the content of linoleic acid (LA) increased significantly in OE but deceased in OPRi. CONCLUSIONS: This is the first study to provide four copies of the OPR gene that regulates LA metabolism, can be used for the molecular mechanism of LA and optimizing fatty acid profiles in oilseed for breeding programs.
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Brassica napus , Brassica napus/genética , Brassica napus/metabolismo , Células Clonais/metabolismo , Ácidos Graxos/metabolismo , Ácido Linoleico/metabolismo , Melhoramento Vegetal , Óleo de Brassica napus/metabolismoRESUMO
Several studies have confirmed that microRNAs (miRNAs) are promising markers for body fluid identification since they were introduced to this field. However, there is no consensus on the choice of reference genes and identification strategies. In this study, 13 potential candidate miRNAs were screened from three forensically relevant body fluid datasets, and the expression of 12 markers in five body fluids was determined using a real-time quantitative method. Two probabilistic approaches, Naive Bayes (NB) and partial least squares discriminant analysis (PLS-DA), were then applied to predict the origin of the samples to determine whether probabilistic methods are helpful in body fluid identification using miRNA quantitative data. Furthermore, 14 reference combinations were used to validate the influence of different reference choices on the predicted results simultaneously. Our results showed that in the NB model, leave-one-out cross-validation (LOOCV) achieved 100% accuracy and the prediction accuracy of the test set was 100% in most reference combinations. In the PLS-DA model, the first two components could interpret about 80% expression variance and LOOCV achieved 100% accuracy when miR-92a-3p was used as the reference. This study preliminarily proved that probabilistic approaches hold huge potential in miRNA-based body fluid identification, and the choice of references influences the prediction results to a certain extent.
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Líquidos Corporais , MicroRNAs , Teorema de Bayes , Biomarcadores , Estudos de Viabilidade , Genética Forense , Humanos , MicroRNAs/genética , Saliva , SêmenRESUMO
RNA molecules, including mRNAs and microRNAs (miRNAs), have been used for forensic body fluid identification. Specific body fluids present unique mRNA expression patterns, while miRNAs identifying body fluids are mainly differentially expressed. miRNAs are thought to be more stable than mRNAs, although this lacks adequate supporting data. In this study, we addressed perceived concerns regarding the stability of miRNAs and mRNAs in blood samples. The samples used in this study involved three groups. First, environmentally-degraded blood stain samples were exposed to a range of environmental conditions over 1-360 days to degrade naturally. Second, simulated-degraded samples were prepared using RNase A or high temperature (80 °C). Furthermore, two authentic casework samples that were proven to be degraded from short tandem repeat (STR) profiles were analyzed. mRNAs and miRNAs present in the same blood samples were simultaneously detected through reverse transcriptase qPCR (RT-qPCR). Furthermore, mRNAs expression was determined by an mRNA multiplex PCR system. Our results showed that both mRNAs and miRNAs were stable in dry environments. The stability of miRNAs was relatively higher than that of mRNAs in humid environments or at high temperature. RNase A had the most serious impact on RNA stability, both mRNA profiles and miRNAs expression patterns were altered. The results of this study provide data and support to demonstrate that miRNAs represent more stable RNA molecules in body fluid identification compared to mRNAs.
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MicroRNAs , Humanos , MicroRNAs/genética , Estabilidade de RNA , RNA Mensageiro/genética , Reação em Cadeia da Polimerase em Tempo RealRESUMO
Semantic segmentation is a crucial image understanding task, where each pixel of image is categorized into a corresponding label. Since the pixel-wise labeling for ground-truth is tedious and labor intensive, in practical applications, many works exploit the synthetic images to train the model for real-word image semantic segmentation, i.e., Synthetic-to-Real Semantic Segmentation (SRSS). However, Deep Convolutional Neural Networks (CNNs) trained on the source synthetic data may not generalize well to the target real-world data. To address this problem, there has been rapidly growing interest in Domain Adaption technique to mitigate the domain mismatch between the synthetic and real-world images. Besides, Domain Generalization technique is another solution to handle SRSS. In contrast to Domain Adaption, Domain Generalization seeks to address SRSS without accessing any data of the target domain during training. In this work, we propose two simple yet effective texture randomization mechanisms, Global Texture Randomization (GTR) and Local Texture Randomization (LTR), for Domain Generalization based SRSS. GTR is proposed to randomize the texture of source images into diverse unreal texture styles. It aims to alleviate the reliance of the network on texture while promoting the learning of the domain-invariant cues. In addition, we find the texture difference is not always occurred in entire image and may only appear in some local areas. Therefore, we further propose a LTR mechanism to generate diverse local regions for partially stylizing the source images. Finally, we implement a regularization of Consistency between GTR and LTR (CGL) aiming to harmonize the two proposed mechanisms during training. Extensive experiments on five publicly available datasets (i.e., GTA5, SYNTHIA, Cityscapes, BDDS and Mapillary) with various SRSS settings (i.e., GTA5/SYNTHIA to Cityscapes/BDDS/Mapillary) demonstrate that the proposed method is superior to the state-of-the-art methods for domain generalization based SRSS.
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In the past decade, mRNA markers have been well demonstrated as promising molecular markers in forensic body fluid identification (BFI), and successfully used in wide applications. Several studies have assessed the performance of semen-specific mRNA markers in distinguishing semen from other common body fluids at the crime scene. Infertility has been reported as a global health problem that is affecting approximately 15% of couples worldwide. Therefore, it is important for forensic researchers to consider the impact of infertility on semen identification. This study aimed to explore the effect of semen from infertile men (hereinafter "infertile semen") on BFI and to identify semen-specific mRNAs that can efficiently and accurately distinguish normal and infertile semen samples from other body fluids. Results showed that the selected five mRNAs (KLK3, TGM4, SEMG1, PRM1, and PRM2) performed a significantly high semen specificity in normal semen. Moreover, KLK3 was slightly influenced by infertile semen samples with over 98% positive results in all semen samples. The accuracy to predict normal semen reached up to 96.6% using the discrimination function Y1 with KLK3 and PRM1. However, when the infertile semen samples were included in discrimination function (function Y2 with KLK3), the accuracy rate of semen identification (including the normal and infertile semen) was down to 89.5%. Besides, the sensitivity of multiplex assay could reach down to 50pg. Our results suggest that it is important to consider the presence of infertile semen when using mRNAs to identify semen samples, which would have a far-reaching impact in forensic identification.
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Líquidos Corporais , Infertilidade Masculina , Biomarcadores , Humanos , Infertilidade Masculina/genética , Masculino , RNA Mensageiro/genética , SêmenRESUMO
BACKGROUND: Klebsiella pneumonia, a Gram-negative bacterium belonging to the genus Enterobacter, causes many human and livestock diseases. Notably, infected goats may develop pneumonia, septicemia, which can lead to occasional death, resulting in great economic losses in goat-farming industry. However, there are little systematic methods for detection of goat Klebsiella pneumoniae in livestock production. RESULTS: In this study, we developed a Klebsiella pneumoniae goat polyclonal antibody and established an indirect ELISA method to detect the Klebsiella pneumoniae. After screening and optimizing the conditions for detection, we determined the optimal working dilutions of the coated-bacterial antigen, the polyclonal antibody, and the enzyme-labeled secondary antibody that were 1:800 (2.99 × 107 CFU/ml), 1:6400, and 1:5000, respectively. The optimal condition of coating and blocking were both 4 °C for 12 h. The optimal dilution buffers of bacterial antigen, the antibodies, and the blocking buffer were 0.05 mol/L carbonate buffer, 1% BSA phosphate buffer, and 1.5% BSA carbonate buffer, respectively. The cut-off value was determined to be 0.28, and the analytical sensitivity was 1:800 (dilution of a positive sample). Furthermore, there was no cross-reaction between the coated antigen and goat serum positive for antibodies against other bacteria, indicating that indirect ELISA could detect Klebsiella pneumoniae specifically in most cases. The average coefficients of variation of intra-assay and inter-assay were 4.37 and 5.17% indicating favorable reproducibility of indirect ELISA. In the detection of clinical veterinary samples, the positive rate of indirect ELISA was 6.74%, higher than that of conventional agglutination assays. CONCLUSIONS: Taken together, we successfully established an indirect ELISA method for detecting antibodies against Klebsiella pneumoniae in goats, which can be applied in production.
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Anticorpos Antibacterianos/sangue , Infecções por Klebsiella/veterinária , Klebsiella pneumoniae/imunologia , Animais , Ensaio de Imunoadsorção Enzimática/métodos , Ensaio de Imunoadsorção Enzimática/veterinária , Doenças das Cabras/diagnóstico , Doenças das Cabras/microbiologia , Cabras , Infecções por Klebsiella/diagnóstico , Infecções por Klebsiella/imunologia , Sensibilidade e EspecificidadeRESUMO
Intestinal mucosa is the largest immune organ in animals, and its immune function is directly related to the resistance against various diseases. Taishan Pinus massoniana pollen polysaccharides (TPPPS) have been recognized as an effective vaccine adjuvant and potential immune enhancer against viral infections. However, little is known about their direct immune-enhancing activity on intestinal mucosa. In this study, we extracted the polysaccharides from Taishan masson pine pollen to investigate its promotive effect on intestinal mucosal immunity. A total of 120 1-day-old chickens were divided into 4 groups and inoculated with PBS or 3 different doses of TPPPS (10 mg/mL, 20 mg/mL, and 40 mg/mL), respectively. Feces, intestinal specimens, and serum samples were collected from the chickens at 7, 14, and 21 d after inoculation. The antibodies in serum, mucosal secretion of IgA, structure of intestinal villi, and expressions of cytokine genes and mucosal immune-related genes in the chickens were all significantly improved by TPPPS treatments. At 21 d after inoculation following the challenge of Newcastle disease virus, the chickens inoculated with 20 and 40 mg/mL TPPPS exhibited decreased weight loss and reduced intestinal pathologic damage and viral loads in the intestine. In summary, our results demonstrate that TPPPS can enhance mucosal immunity and promote intestinal villi development. This study has established the foundation for the development of novel immune-enhancing agent with immune-regulatory effects on intestinal mucosa.
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Galinhas/imunologia , Imunidade nas Mucosas/efeitos dos fármacos , Mucosa Intestinal/imunologia , Pinus , Pólen/química , Polissacarídeos/farmacologia , Animais , Citocinas/análise , Imunoglobulina A Secretora/análise , Imunoglobulina G/sangue , Distribuição Aleatória , Organismos Livres de Patógenos EspecíficosRESUMO
The protozoan Trypanosoma cruzi almost invariably establishes life-long infections in humans and other mammals, despite the development of potent host immune responses that constrain parasite numbers. The consistent, decades-long persistence of T. cruzi in human hosts arises at least in part from the remarkable level of genetic diversity in multiple families of genes encoding the primary target antigens of anti-parasite immune responses. However, the highly repetitive nature of the genome-largely a result of these same extensive families of genes-have prevented a full understanding of the extent of gene diversity and its maintenance in T. cruzi. In this study, we have combined long-read sequencing and proximity ligation mapping to generate very high-quality assemblies of two T. cruzi strains representing the apparent ancestral lineages of the species. These assemblies reveal not only the full repertoire of the members of large gene families in the two strains, demonstrating extreme diversity within and between isolates, but also provide evidence of the processes that generate and maintain that diversity, including extensive gene amplification, dispersion of copies throughout the genome and diversification via recombination and in situ mutations. Gene amplification events also yield significant copy number variations in a substantial number of genes presumably not required for or involved in immune evasion, thus forming a second level of strain-dependent variation in this species. The extreme genome flexibility evident in T. cruzi also appears to create unique challenges with respect to preserving core genome functions and gene expression that sets this species apart from related kinetoplastids.