Discovery and evaluation of a novel 18F-labeled vasopressin 1a receptor PET ligand with peripheral binding specificity.

The arginine-vasopressin (AVP) hormone plays a pivotal role in regulating various physiological processes, such as hormone secretion, cardiovascular modulation, and social behavior. Recent studies have highlighted the V1a receptor as a promising therapeutic target. In-depth insights into V1a receptor-related pathologies, attained through in vivo imaging and quantification in both peripheral organs and the central nervous system (CNS), could significantly advance the development of effective V1a inhibitors. To address this need, we develop a novel V1a-targeted positron emission tomography (PET) ligand, [18F]V1A-2303 ([18F]8), which demonstrates favorable in vitro binding affinity and selectivity for the V1a receptor. Specific tracer binding in peripheral tissues was also confirmed through rigorous cell uptake studies, autoradiography, biodistribution assessments. Furthermore, [18F]8 was employed in PET imaging and arterial blood sampling studies in healthy rhesus monkeys to assess its brain permeability and specificity, whole-body distribution, and kinetic properties. Our research indicated [18F]8 as a valuable tool for noninvasively studying V1a receptors in peripheral organs, and as a foundational element for the development of next-generation, brain-penetrant ligands specifically designed for the CNS.

Postoperative delirium risk in patients with hyperlipidemia: A prospective cohort study.

STUDY OBJECTIVE: Hyperlipidemia and postoperative delirium (POD) significantly affect patients' quality of life; however, the question of whether hyperlipidemia constitutes a risk factor for POD remain unclear. This study aimed to investigate whether patients with hyperlipidemia face elevated risks of developing POD and to identify potential causes for this increased risk. DESIGN: A prospective cohort study. SETTING: Operating room. PATIENTS: Patients were adults scheduled for colorectal cancer surgery in 2023. EXPOSURES: The exposure factor was hyperlipidemia, and the patients were divided into hyperlipidemia group and non-hyperlipidemia group. MEASUREMENTS: POD occurrence within three days post-surgery was assessed using the 3-Minute Diagnostic Interview for Confusion Assessment Method. Over one year, these patients were monitored through telephone to evaluate their survival and cognitive function. Logistic regression analysis was performed to evaluate the risk factors for POD development in patients with hyperlipidemia and to construct a clinical prediction model. MAIN RESULTS: This study included 555 patients. POD incidence was 21.6% in the hyperlipidemia group and 12.7% in the non-hyperlipidemia group. One year following surgery, patients with hyperlipidemia and POD exhibited significantly higher rates of mortality and cognitive decline than did those without POD (p < 0.001). A multifactorial logistic clinical prediction model was constructed from seven independent risk factors for POD development in patients with hyperlipidemia, including education, preoperative total cholesterol (TC), preoperative triglyceride (TG), diet, history of hypertension, Sedation-Agitation Scale, and postoperative trimethylamine N-oxide expression level, and it had the highest predictive value for POD development in patients with hyperlipidemia. CONCLUSIONS: Compared with those without hyperlipidemia, patients with hyperlipidemia had higher POD incidence. Elevated serum TC and TG levels are independent risk factors for POD in patients with hyperlipidemia. The study's findings could help develop strategies for improving POD and hyperlipidemia treatment.

N6-methyladenosine triggers renal fibrosis via enhancing translation and stability of ZEB2 mRNA.

In recent years, a surge in studies investigating N6-methyladenosine (m6A) modification in human diseases has occurred. However, the specific roles and mechanisms of m6A in kidney disease remain incompletely understood. This study revealed that m6A plays a positive role in regulating renal fibrosis (RF) by inducing epithelial-to-mesenchymal phenotypic transition (EMT) in renal tubular cells. Through comprehensive analyses, including m6A sequencing, RNA-seq, and functional studies, we confirmed the pivotal involvement of zinc finger E-box binding homeobox 2 (ZEB2) in m6A-mediated RF and EMT. Notably, the m6A-modified coding sequence of ZEB2 mRNA significantly enhances its translational elongation and mRNA stability by interacting with the YTHDF1/eEF-2 complex and IGF2BP3, respectively. Moreover, targeted demethylation of ZEB2 mRNA using the dm6ACRISPR system substantially decreases ZEB2 expression and disrupts the EMT process in renal tubular epithelial cells. In vivo and clinical data further support the positive influence of m6A/ZEB2 on RF progression. Our findings highlight the m6A-mediated regulation of RF through ZEB2, revealing a novel therapeutic target for RF treatment and enhancing our understanding of the impact of mRNA methylation on kidney disease.

Dietary intake and glutamine-serine metabolism control pathologic vascular stiffness.

Perivascular collagen deposition by activated fibroblasts promotes vascular stiffening and drives cardiovascular diseases such as pulmonary hypertension (PH). Whether and how vascular fibroblasts rewire their metabolism to sustain collagen biosynthesis remains unknown. Here, we found that inflammation, hypoxia, and mechanical stress converge on activating the transcriptional coactivators YAP and TAZ (WWTR1) in pulmonary arterial adventitial fibroblasts (PAAFs). Consequently, YAP and TAZ drive glutamine and serine catabolism to sustain proline and glycine anabolism and promote collagen biosynthesis. Pharmacologic or dietary intervention on proline and glycine anabolic demand decreases vascular stiffening and improves cardiovascular function in PH rodent models. By identifying the limiting metabolic pathways for vascular collagen biosynthesis, our findings provide guidance for incorporating metabolic and dietary interventions for treating cardiopulmonary vascular disease.

Comparison of thermal comfort between different heating systems and adaptation to different indoor climates in winter.

Individual heating systems, such as the air-source heat pump (ASHP) air-conditioner or floor heating (FH), are usually used by people living in the hot summer and cold winter (HSCW) zone of China to heat indoor climates in the winter. However, little research has been conducted in the HSCW zone on the thermal comfort difference between indoor climates heated by ASHP air-conditioners and those heated by floor heating, as well as how occupants adapt to different indoor climates. We conducted a comparative field experiment in ASHP-heated and FH-heated apartments in Nanjing to investigate how different types of heating systems influence the thermal sensation of occupants, and we conducted a comparative field experiment in ASHP-heated office buildings and naturally ventilated teaching buildings in Shanghai to investigate how occupants adapt to different indoor thermal environments. Indoor environmental parameters and body surface temperatures were measured using instruments, and occupants' thermal sensation, activity level, and clothing were evaluated using the questionnaire. The results show that floor heating improves thermal comfort by raising foot temperature compared to the ASHP air-conditioner, and that occupants become acclimatized to different indoor climates by adjusting neutral operative temperature. According to the findings, there is no need to overheat the indoor environment in the HSCW zone because occupants can adapt to their experienced thermal environment and it is critical to maintain warm foot temperature in the cool/cold indoor environment.

Clinical observation of extraction-site incisional hernia after laparoscopic colorectal surgery.

BACKGROUND: Laparoscopic colorectal cancer surgery increases the risk of incisional hernia (IH) at the tumor extraction site. AIM: To investigate the incidence of IH at extraction sites following laparoscopic colorectal cancer surgery and identify the risk factors for IH incidence. METHODS: This study retrospectively analyzed the data of 1614 patients who underwent laparoscopic radical colorectal cancer surgery with tumor extraction through the abdominal wall at our center between January 2017 and December 2022. Differences in the incidence of postoperative IH at different extraction sites and the risk factors for IH incidence were investigated. RESULTS: Among the 1614 patients who underwent laparoscopic radical colorectal cancer surgery, 303 (18.8%), 923 (57.2%), 171 (10.6%), and 217 (13.4%) tumors were extracted through supraumbilical midline, infraumbilical midline, umbilical, and off-midline incisions. Of these, 52 patients developed IH in the abdominal wall, with an incidence of 3.2%. The incidence of postoperative IH was significantly higher in the off-midline incision group (8.8%) than in the middle incision groups [the supraumbilical midline (2.6%), infraumbilical midline (2.2%), and umbilical incision (2.9%) groups] (χ2 = 24.985; P < 0.05). Univariate analysis showed that IH occurrence was associated with age, obesity, sex, chronic cough, incision infection, and combined diabetes, anemia, and hypoproteinemia (P < 0.05). Similarly, multivariate analysis showed that off-midline incision, age, sex (female), obesity, incision infection, combined chronic cough, and hypoproteinemia were independent risk factors for IH at the site of laparoscopic colorectal cancer surgery (P < 0.05). CONCLUSION: The incidence of postoperative IH differs between extraction sites for laparoscopic colorectal cancer surgery. The infraumbilical midline incision is associated with a lower hernia rate and is thus a suitable tumor extraction site.

Terminally differentiated cytotoxic CD4+ T cells were clonally expanded in the brain lesion of radiation-induced brain injury.

BACKGROUND: Accumulating evidence supports the involvement of adaptive immunity in the development of radiation-induced brain injury (RIBI). Our previous work has emphasized the cytotoxic function of CD8+ T cells in RIBI. In this study, we aimed to investigate the presence and potential roles of cytotoxic CD4+ T cells (CD4+ CTLs) in RIBI to gain a more comprehensive understanding of adaptive immunity in this context. MAIN TEXT: Utilizing single-cell RNA sequencing (scRNA-seq), we analyzed 3934 CD4+ T cells from the brain lesions of four RIBI patients and identified six subclusters within this population. A notable subset, the cytotoxic CD4+ T cells (CD4+ CTLs), was marked with high expression of cytotoxicity-related genes (NKG7, GZMH, GNLY, FGFBP2, and GZMB) and several chemokine and chemokine receptors (CCL5, CX3CR1, and CCL4L2). Through in-depth pseudotime analysis, which simulates the development of CD4+ T cells, we observed that the CD4+ CTLs exhibited signatures of terminal differentiation. Their functions were enriched in protein serine/threonine kinase activity, GTPase regulator activity, phosphoprotein phosphatase activity, and cysteine-type endopeptidase activity involved in the apoptotic signaling pathway. Correspondingly, mice subjected to gamma knife irradiation on the brain showed a time-dependent infiltration of CD4+ T cells, an increase of MHCII+ cells, and the existence of CD4+ CTLs in lesions, along with an elevation of apoptotic-related proteins. Finally, and most crucially, single-cell T-cell receptor sequencing (scTCR-seq) analysis at the patient level determined a large clonal expansion of CD4+ CTLs in lesion tissues of RIBI. Transcriptional factor-encoding genes TBX21, RORB, and EOMES showed positive correlations with the cytotoxic functions of CD4+ T cells, suggesting their potential to distinguish RIBI-related CD4+ CTLs from other subsets. CONCLUSION: The present study enriches the understanding of the transcriptional landscape of adaptive immune cells in RIBI patients. It provides the first description of a clonally expanded CD4+ CTL subset in RIBI lesions, which may illuminate new mechanisms in the development of RIBI and offer potential biomarkers or therapeutic targets for the disease.

N6-methyladenosine facilitates mitochondrial fusion of colorectal cancer cells via induction of GSH synthesis and stabilization of OPA1 mRNA.

Mitochondria undergo fission and fusion that are critical for cell survival and cancer development, while the regulatory factors for mitochondrial dynamics remain elusive. Herein we found that RNA m6A accelerated mitochondria fusion of colorectal cancer (CRC) cells. Metabolomics analysis and function studies indicated that m6A triggered the generation of glutathione (GSH) via the upregulation of RRM2B-a p53-inducible ribonucleotide reductase subunit with anti-reactive oxygen species potential. This in turn resulted in the mitochondria fusion of CRC cells. Mechanistically, m6A methylation of A1240 at 3'UTR of RRM2B increased its mRNA stability via binding with IGF2BP2. Similarly, m6A methylation of A2212 at the coding sequence (CDS) of OPA1-an essential GTPase protein for mitochondrial inner membrane fusion-also increased mRNA stability and triggered mitochondria fusion. Targeting m6A through the methyltransferase inhibitor STM2457 or the dm6ACRISPR system significantly suppressed mitochondria fusion. In vivo and clinical data confirmed the positive roles of the m6A/mitochondrial dynamics in tumor growth and CRC progression. Collectively, m6A promoted mitochondria fusion via induction of GSH synthesis and OPA1 expression, which facilitated cancer cell growth and CRC development.

Critical review and recent advances of emerging real-time and non-destructive strategies for meat spoilage monitoring.

Monitoring and evaluating food quality, especially meat quality, has received a growing interest to ensure human health and decrease waste of raw materials. Standard analytical approaches used for meat spoilage assessment suffer from time consumption, being labor-intensive, operation complexity, and destructiveness. To overcome shortfalls of these traditional methods and monitor spoilage microorganisms or related metabolites of meat products across the supply chain, emerging analysis devices/systems with higher sensitivity, better portability, on-line/in-line, non-destructive and cost-effective property are urgently needed. Herein, we first overview the basic concepts, causes, and critical monitoring indicators associated with meat spoilage. Then, the conventional detection methods for meat spoilage are outlined objectively in their strengths and weaknesses. In addition, we place the focus on the recent research advances of emerging non-destructive devices and systems for assessing meat spoilage. These novel strategies demonstrate their powerful potential in the real-time evaluation of meat spoilage.

Exploring the impacts of senescence on implantation and early embryonic development using totipotent cell-derived blastoids.

INTRODUCTION: Advanced maternal age is associated with reduced implantation and pregnancy rates, yet the underlying mechanisms remain poorly understood, and research models are limited. OBJECTIVES: Here, we aim to elucidate the impacts of senescence on implantation ability by employing blastoids to construct a novel research model. METHODS: We used a novel three-dimensional system with totipotent blastomere-like cells (TBLCs) to construct TBL-blastoids and established senescence-related embryo models derived from oxidative stress-induced TBLCs. RESULTS: Morphological and transcriptomic analyses revealed that TBL-blastoids exhibited characteristic blastocyst morphology, cell lineages, and a higher consistency in developmental rate. TBL-blastoids demonstrated the ability to develop into postimplantation structures in vitro and successfully implanted into mouse uteri, inducing decidualization and forming embryonic tissues. Importantly, senescence impaired the implantation potential of TBL-blastoids, effectively mimicking the impaired implantation ability and reduced pregnancy rates associated with advanced age. Furthermore, analysis of differentially expressed genes (DEGs) in human homologous deciduae revealed enrichment in multiple fertility-related diseases and other complications of pregnancy. The genes implicated in these diseases and the common DEGs identified in the lineage-like cells of the two types of TBL-blastoids and deciduae may represent potential targets for addressing impaired implantation potential. CONCLUSION: These results unveiled that TBL blastoids are an improved model for investigating implantation and early postimplantation, offering valuable insights into pregnancy-related disorders in women with advanced age and potential targets for therapeutic interventions.

Brachial Plexus Root Avulsion Injury-Induced Endothelin-Converting Enzyme-Like 1 Overexpression Is Associated with Injured Motor Neurons Survival.

Brachial plexus root avulsion (BPRA) injury arises from challenging delivery during childbirth, sports-related incidents, or car accidents, leading to extensive loss of motor neurons (MNs) and subsequent paralysis, including both motor and sensory impairment. Surgical nerve re-implantation cannot effectively restore motor function, and the survival of injured MNs is vital for axon regeneration and re-innervating the target muscles. Therefore, identifying novel molecular targets to improve injured MNs survival is of great significance in the treatment of BPRA injuries. Endothelin-converting enzyme-like 1 (ECEL1), a membrane-bound metallopeptidase, was initially identified as a molecule associated with nerve injuries. Damaged neurons exhibit a significant increase in the expression of ECEL1 following various types of nerve injuries, such as optic nerve injury and sciatic nerve injury. This study aimed to investigate the relationship between ECEL1 overexpression and the survival of injured MNs following BPRA injury. Our results observed a significant elevation in ECEL1 expression in injured MNs and positively correlated with MNs survival following BPRA injury. The transcription of ECEL1 is regulated by the transcription factors c-Jun and ATF3 in the context of BPRA injury, which is consistent with previous other nerve injuries study. In addition, the expression of TrkA gradually decreases in ECEL1-positive MNs and ECEL1 possibly preserves the activity of downstream AKT-GSK3ß pathway of TrkA in injured MNs. In conclusion, our results introduce a promising therapeutic molecular target to assist re-implantation surgery for the treatment of BPRA injury.

Altered expression of the Plexin-B2 system in tuberous sclerosis complex and focal cortical dysplasia IIb lesions.

Tuberous sclerosis complex (TSC) and focal cortical dysplasia (FCD) type IIb are the predominant causes of drug-refractory epilepsy in children. Dysmorphic neurons (DNs), giant cells (GCs), and balloon cells (BCs) are the most typical pathogenic profiles in cortical lesions of TSC and FCD IIb patients. However, mechanisms underlying the pathological processes of TSC and FCD IIb remain obscure. The Plexin-B2-Sema4C signalling pathway plays critical roles in neuronal morphogenesis and corticogenesis during the development of the central nervous system. However, the role of the Plexin-B2 system in the pathogenic process of TSC and FCD IIb has not been identified. In the present study, we investigated the expression and cell distribution characteristics of Plexin-B2 and Sema4C in TSC and FCD IIb lesions with molecular technologies. Our results showed that the mRNA and protein levels of Plexin-B2 expression were significantly increased both in TSC and FCD IIb lesions versus that in the control cortex. Notably, Plexin-B2 was also predominantly observed in GCs in TSC epileptic lesions and BCs in FCD IIb lesions. In contrast, the expression of Sema4C, the ligand of Plexin-B2, was significantly decreased in DNs, GCs, and BCs in TSC and FCD IIb epileptic lesions. Additionally, Plexin-B2 and Sema4C were expressed in astrocytes and microglia cells in TSC and FCD IIb lesions. Furthermore, the expression of Plexin-B2 was positively correlated with seizure frequency in TSC and FCD IIb patients. In conclusion, our results showed the Plexin-B2-Sema4C system was abnormally expressed in cortical lesions of TSC and FCD IIb patients, signifying that the Plexin-B2-Sema4C system may play a role in the pathogenic development of TSC and FCD IIb.

Upregulated Tß4 expression in inflammatory bowel disease impairs the intestinal mucus barrier by inhibiting autophagy in mice.

Disrupted intestinal barrier homeostasis is fundamental to inflammatory bowel disease. Thymosin ß4 (Tß4) improves inflammation and has beneficial effects in dry-eye diseases, but its effects on the intestinal mucus barrier remain unknown. Therefore, this study evaluated the underlying regulatory mechanisms and effects of Tß4 by examining Tß4 expression in a mouse model with dextran sodium sulfate (DSS)-induced colitis and colonic barrier damage. Additionally, we intraperitoneally injected C57BL/6 mice with Tß4 to assess barrier function, microtubule-associated protein 1 light chain 3 (LC3II) protein expression, and autophagy. Finally, normal human colon tissue and colon carcinoma cells (Caco2) were cultured to verify Tß4-induced barrier function and autophagy changes. Mucin2 levels decreased, microbial infiltration increased, and Tß4 expression increased in the colitis mouse model versus the control mice, indicating mucus barrier damage. Moreover, Tß4-treated C57BL/6 mice had damaged intestinal mucus barriers and decreased LC3II levels. Tß4 also inhibited colonic mucin2 production, disrupted tight junctions, and downregulated autophagy; these results were confirmed in Caco2 cells and normal human colon tissue. In summary, Tß4 may be implicated in colitis by compromising the integrity of the intestinal mucus barrier and inhibiting autophagy. Thus, Tß4 could be a new diagnostic marker for intestinal barrier defects.

Nutritional screening and assessment tools for patients with cirrhosis based on the Global Leadership Initiative on Malnutrition criteria.

BACKGROUND: Malnutrition is highly prevalent and associated with complications and mortality in patients with cirrhosis. METHODS: This was a prospective observational study. Patients with cirrhosis were screened using the Nutritional Risk Screening 2002, the Royal Free Hospital-Nutritional Prioritizing Tool and the Skeletal Muscle Index. Then, the sensitivity, specificity, positive and negative predictive values, and consistency with the Global Leadership Initiative on Malnutrition criteria results were calculated. We also analysed the association between nutritional status and short-term prognosis. RESULTS: We enrolled 125 patients with cirrhosis, of whom 59.20% and 60.00% were malnourished based on the Global Leadership Initiative on Malnutrition criteria and Skeletal Muscle Index. Some 53.60% and 65.60%, respectively, were classified medium-to-high nutritional risk by Nutritional Risk Screening 2002 and the Royal Free Hospital-Nutritional Prioritizing Tool. The Royal Free Hospital-Nutritional Prioritizing Tool had the best predictive value, and it was more sensitive and had a better negative predictive value than the Nutritional Risk Screening 2002 Tool. The Skeletal Muscle Index also had good sensitivity and predictive value. The Royal Free Hospital-Nutritional Prioritizing Tool, Skeletal Muscle Index and Global Leadership Initiative on Malnutrition criteria showed high concordance. The 3- and 6-month mortality rates were significantly higher for patients with moderate-to-high nutritional risk or malnutrition, regardless of the tool. CONCLUSIONS: When assessing cirrhosis with the Global Leadership Initiative on Malnutrition criteria, the Royal Free Hospital-Nutritional Prioritizing Tool is best for nutritional screening and the Skeletal Muscle Index is also a good nutritional assessment tool.

APR-246 increases tumor antigenicity independent of p53.

We previously reported that activation of p53 by APR-246 reprograms tumor-associated macrophages to overcome immune checkpoint blockade resistance. Here, we demonstrate that APR-246 and its active moiety, methylene quinuclidinone (MQ) can enhance the immunogenicity of tumor cells directly. MQ treatment of murine B16F10 melanoma cells promoted activation of melanoma-specific CD8+ T cells and increased the efficacy of a tumor cell vaccine using MQ-treated cells even when the B16F10 cells lacked p53. We then designed a novel combination of APR-246 with the TLR-4 agonist, monophosphoryl lipid A, and a CD40 agonist to further enhance these immunogenic effects and demonstrated a significant antitumor response. We propose that the immunogenic effect of MQ can be linked to its thiol-reactive alkylating ability as we observed similar immunogenic effects with the broad-spectrum cysteine-reactive compound, iodoacetamide. Our results thus indicate that combination of APR-246 with immunomodulatory agents may elicit effective antitumor immune response irrespective of the tumor's p53 mutation status.

A Synthetic Steroid 5α-Androst-3ß, 5, 6ß-triol Alleviates Radiation-Induced Brain Injury in Mice via Inhibiting GBP5/NF-κB/NLRP3 Signal Axis.

Radiotherapy for head and neck tumors can lead to a severe complication known as radiation-induced brain injury (RIBI). However, the underlying mechanism of RIBI development remains unclear, and limited prevention and treatment options are available. Neuroactive steroids have shown potential in treating neurological disorders. 5α-Androst-3ß, 5, 6ß-triol (TRIOL), a synthetic neuroprotective steroid, holds promise as a treatment candidate for RIBI patients. However, the neuroprotective effects and underlying mechanism of TRIOL on RIBI treatment are yet to be elucidated. In the present study, our findings demonstrate TRIOL's potential as a neuroprotective agent against RIBI. In gamma knife irradiation mouse model, TRIOL treatment significantly reduced brain necrosis volume, microglial activation, and neuronal loss. RNA-sequencing, immunofluorescence, real-time quantitative polymerase chain reaction, siRNA transfection, and western blotting techniques revealed that TRIOL effectively decreased microglial activation, proinflammatory cytokine release, neuron loss, and guanylate-binding protein 5 (GBP5) expression, along with its downstream signaling pathways NF-κB and NLRP3 activation in vitro. In summary, TRIOL effectively alleviate RIBI by inhibiting the GBP5/NF-κB/NLRP3 signal axis, reducing microglia activation and pro-inflammation cytokines release, rescuing neuron loss. This study highlights the potential of TRIOL as a novel and promising therapy drug for RIBI treatment.

Isothermal Amplification-Based Detection of Single-Base RNA N6-Methyladenosine.

N6-methyladenosine (m6A) has recently gained much attention due to its diverse biological functions. Currently, the commonly used detection methods for locus-specific m6A marks are complicated to operate, it is difficult to quantify the methylation level, and they have high false-positive levels. Here, we report a new method for locus-specific m6A detection based on the methylate-sensitive endonuclease activity of MazF and the simultaneous amplification and testing (SAT) method, termed "m6A-MazF-SAT". Mechanically, MazF fails to cleave the A (m6A) CA motif; therefore, the undigested template can be SAT-amplified using specific probes targeting the upstream and downstream of sites of interest. Fluorescent signals of SAT amplification can be detected by real-time PCR, and therefore, they achieve the detection of m6A existence. After the condition optimization, m6A-MazF-SAT can significantly, accurately, and rapidly detect the m6A-modified sites in mRNA, rRNA, and lncRNA at the fmol level, as well as 10% m6A at the fmol level. In addition, m6A-MazF-SAT can quantify the abundance of target m6A in biological samples and can be used for the inhibitor selection of m6A-related enzymes. Together, we offer a new approach to detect locus-specific m6A both qualitatively and quantitatively; it is easy to operate, results can be obtained rapidly, and it has low false-positive levels and high repeatability.

Bayesian phylodynamic analysis reveals the evolutionary history and the dispersal patterns of citrus tristeza virus in China based on the p25 gene.

BACKGROUND: Citrus tristeza virus (CTV) is one of the most serious threats to the citrus industry, and is present in both wild and cultivated citrus. The origin and dispersal patterns of CTV is still poorly understood in China. METHODS: In this study, 524 CTV suspected citrus samples from China were collected, including 354 cultivated citrus samples and 174 wild citrus samples. Finally, 126 CTV coat protein sequences were obtained with time-stamped from 10 citrus origins in China. Bayesian phylodynamic inference were performed for CTV origin and dispersal patterns study in China. RESULT: We found that CTV was mainly distributed in southern and coastal areas of China. The substitution rate of CTV was 4.70 × 10- 4 subs/site/year (95% credibility interval: 1.10 × 10- 4 subs/site/year ~ 9.10 × 10- 4 subs/site/year), with a slight increasing trend in CTV populations between 1990 and 2006. The CTV isolates in China shared a most common recent ancestor around 1875 (95% credibility interval: 1676.57 ~ 1961.02). The CTV in China was originated from wild citrus in Hunan and Jiangxi, and then spread from the wild citrus to cultivated citrus in the growing regions of Sichuan, Chongqing, Hubei, Fujian, Zhejiang, Guangxi and Guangdong provinces. CONCLUSIONS: This study has proved that CTV in China was originated from wild citrus in Hunan and Jiangxi. The spatial-temporal distribution and dispersal patterns has uncovered the population and pandemic history of CTV, providing hints toward a better understanding of the spread and origin of CTV in China.