Metabolic Blockade-Based Genome Mining of Sea Anemone-Associated Streptomyces sp. S1502 Identifies Atypical Angucyclines WS-5995 A-E: Isolation, Identification, Biosynthetic Investigation, and Bioactivities.

Marine symbiotic and epiphyte microorganisms are sources of bioactive or structurally novel natural products. Metabolic blockade-based genome mining has been proven to be an effective strategy to accelerate the discovery of natural products from both terrestrial and marine microorganisms. Here, the metabolic blockade-based genome mining strategy was applied to the discovery of other metabolites in a sea anemone-associated Streptomyces sp. S1502. We constructed a mutant Streptomyces sp. S1502/Δstp1 that switched to producing the atypical angucyclines WS-5995 A-E, among which WS-5995 E is a new compound. A biosynthetic gene cluster (wsm) of the angucyclines was identified through gene knock-out and heterologous expression studies. The biosynthetic pathways of WS-5995 A-E were proposed, the roles of some tailoring and regulatory genes were investigated, and the biological activities of WS-5995 A-E were evaluated. WS-5995 A has significant anti-Eimeria tenell activity with an IC50 value of 2.21 µM. The production of antibacterial streptopyrroles and anticoccidial WS-5995 A-E may play a protective role in the mutual relationship between Streptomyces sp. S1502 and its host.

A novel avian intestinal epithelial cell line: its characterization and exploration as an in vitro infection culture model for Eimeria species.

BACKGROUND: The gastrointestinal epithelium plays an important role in directing recognition by the immune system, and epithelial cells provide the host's front line of defense against microorganisms. However, it is difficult to cultivate avian intestinal epithelial cells in vitro for lengthy periods, and the lack of available cell lines limits the research on avian intestinal diseases and nutritional regulation. Chicken coccidiosis is a serious intestinal disease that causes significant economic losses in the poultry industry. In vitro, some cell line models are beneficial for the development of Eimeria species; however, only partial reproduction can be achieved. Therefore, we sought to develop a new model with both the natural host and epithelial cell phenotypes. METHODS: In this study, we use the SV40 large T antigen (SV40T) gene to generate an immortalized cell line. Single-cell screening technology was used to sort positive cell clusters with epithelial characteristics for passage. Polymerase chain reaction (PCR) identification, immunofluorescence detection, and bulk RNA sequencing analysis and validation were used to check the expression of epithelial cell markers and characterize the avian intestinal epithelial cell line (AIEC). AIECs were infected with sporozoites, and their ability to support the in vitro endogenous development of Eimeria tenella was assessed. RESULTS: This novel AIEC consistently expressed intestinal epithelial markers. Transcriptome assays revealed the upregulation of genes associated with proliferation and downregulation of genes associated with apoptosis. We sought to compare E. tenella infection between an existing fibroblast cell line (DF-1) and several passages of AIEC and found that the invasion efficiency was significantly increased relative to that of chicken fibroblast cell lines. CONCLUSIONS: An AIEC will serve as a better in vitro research model, especially in the study of Eimeria species development and the mechanisms of parasite-host interactions. Using AIEC helps us understand the involvement of intestinal epithelial cells in the digestive tract and the immune defense of the chickens, which will contribute to the epithelial innate defense against microbial infection in the gastrointestinal tract.

The unmet needs of patients in the early rehabilitation stage after lung cancer surgery: a qualitative study based on Maslow's hierarchy of needs theory.

PURPOSE: This study aimed to explore the unmet needs of lung cancer patients in early rehabilitation, based on Maslow's hierarchy of needs theory. METHODS: Information on the experiences of 20 patients was collected through semi-structured interviews. The interviews were conducted in the surgical nursing clinic within 1 week of discharge from hospital. The data were analysed using a combination of deductive (theory-driven) and inductive (data-driven) methods, using Maslow's Hierarchy of Needs as a framework for identifying and organising themes. RESULTS: Patients had a mean age of 50.92 years (SD 11.88); n = 11 (55%) were female. Major themes aligned with the dimensions of Maslow's hierarchy of needs model. Five major themes with 12 corresponding sub-themes emerged: (1) physiological needs, including "self-care and independence in life", "return to pre-operative status as soon as possible", "increase exercise under specialist guidance" and "reduce cough and pain and improve sleep quality"; (2) safety and security needs, such as "symptom management", "regulation of the emotions of worry and fear" and "access accurate treatment information"; (3) love and belonging needs, including "accompany family members" and "chat with friends";(4)Esteem needs: "live with dignity";(5) Self-actualization, such as "accept and submit to the reality of cancer" and "live meaningfully". CONCLUSIONS: The findings of this study indicated that there were many unmet needs for patients during the early recovery period after lung cancer surgery. An overview of the different areas of need identified in this study may guide future research and development of interventions to improve patients' quality of life during the home rehabilitation phase.

Xylem formation of Populus euphratica and its response to water-heat factors in the lower reaches of Tarim River, China.

To deeply understand the effects of water and temperature factors on the xylem formation of Populus euphratica, taking the Yingsu section in the lower reaches of Tarim River as an example, we selected micro-coring samples of P. euphratica around monitoring wells F2 and F10 in the 100 and 1500 m distance from the channel of Tarim River. We used wood anatomy method to analyze the xylem anatomy of P. euphratica and its response to water and temperature factors. The results showed that the changes of the total anatomical vessel area and the vessel number of P. euphratica in the two plots were basically consistent during the whole growing season. The vessel number of xylem conduits of P. euphratica increased slowly with the increases of groundwater depth, while the total conduit area increased firstly and then decreased. The total vessel area, minimum vessel area, average vessel area, and maximum vessel area of P. euphratica xylem increased significantly with the increases of temperature in the growing season. The contribution of groundwater depth and air temperature to P. euphratica xylem varied among different growth stages. In the early growing season, air temperature had the largest contribution to the number and total area of xylem conduits of P. euphratica. During the middle growing season, air temperature and groundwater depth jointly affected the parameters of each conduit. During the later growing season, groundwater depth had the largest contribution to the number and total area of conduits. Results of the sensitivity analysis indicated that the groundwater depth sensitive to xylem vessel number change of P. euphratica was 5.2 m and that to the change in the total conduit area was 5.9 m. The temperature sensitive to total vessel area of P. euphratica xylem was 22.0 ℃, and that to average vessel area was 18.5 ℃. Therefore, the sensitive groundwater depth affecting xylem growth was at the range of 5.2-5.9 m, and the sensitive temperature was at the range of 18.5-22 ℃. This study could provide scientific basis for the restoration and protection of P. euphratica forest in the lower reaches of Tarim River.

The Effect of Mesenchymal Stem Cells, Adipose Tissue Derived Stem Cells, and Cellular Stromal Vascular Fraction on the Repair of Acute Anal Sphincter Injury in Rats.

BACKGROUND: Anal sphincter incontinence (ASI) can cause a serious decline in the quality of life and can cause a socioeconomic burden. Studies have shown that bone marrow mesenchymal stem cells (MSC) have significant therapeutic effects on ASI, but the cost and risk of MSC harvest limit their further application. In contrast, adipose tissue derived stem cells (ADSC) and cellular stromal vascular fraction (CSVF) as stem cell sources have multipotency and the advantage of easy harvest. OBJECTIVE: Here we aim to investigate the effects of ADSC and CSVF on treating ASI and compare them to that of bone marrow MSC. METHODS: Bone marrow MSC, ADSC, and CSVF were obtained and labeled with green fluorescent protein (GFP), and CSVF was labeled with DIL. Sprague Dawley (SD) rats were divided into 5 groups. Four groups were injected with 0.2 mL phosphate buffer saline (PBS), 1 × 107/0.2 mL of MSC, ADSC, or CSVF, respectively, after model establishment. The control group received no treatment. The repair was assessed by anal functional tests and immunostaining on day 5 and day 10 after injection. RESULTS: MSC, ADSC, and CSVF significantly promoted tissue repair and the recovery of muscle contraction and electromyographic activity in ASI. The generation of myosatellite cells by injected MSC, ADSC, and CSVF was found in the wounded area. On day 5, CSVF showed highest therapeutic effect, while on day 10, MSC and ADSC showed higher therapeutic effects than CSVF. When comparing the effects of MSC and ADSC, ADSC was slightly better than MSC in the indexes of anal pressure, etc. Conclusion: ADSC and CVSF are alternative stem cell sources for ASI repair.

Agrimol B inhibits colon carcinoma progression by blocking mitochondrial function through the PGC-1α/NRF1/TFAM signaling pathway.

Background: The activation of peroxisome proliferator-activated receptor-γ coactivator 1α (PGC-1α) stimulates the transcription of the downstream target proteins, mitochondrial transcription factor A (TFAM) and nuclear respiratory factor 1 (NRF1), which induces mitochondrial biogenesis and promotes colorectal tumorigenesis. Agrimol B (Agr) is a constituent of Agrimonia pilosa Ledeb. that exerts anticancer effects. Herein, we aimed to investigate the antitumor activity of Agr and its mechanism of action. Methods: The interaction between Agr and PGC-1α was predicted by molecular docking. After the treatment with different concentrations of Agr (0, 144, 288, and 576 nM), the cell viability, migration rate, proliferation rate, and apoptosis rate of human colon cancer HCT116 cells were determined. Mitochondrial activity, cellular reactive oxygen species (ROS), and mitochondrial membrane potential were assessed to measure the regulatory effect of Agr on mitochondrial function. Western blotting (WB) assay was used to examine the expression of PGC-1α, NRF1, and TFAM, as well as of the pro-apoptotic proteins, Bax and Caspase-3, and the antiapoptotic protein (Bcl-2). Finally, subcutaneous tumor xenograft model mice were used to evaluate the effect of Agr on colorectal cancer (CRC) in vivo. Results: The molecular docking results revealed a high likelihood of Agr interacting with PGC-1α. Agr inhibited the proliferation and migration of HCT116 cells, promoted ROS production and mitochondrial oxidative stress, inhibited mitochondrial activity, and decreased mitochondrial membrane potential. Agr induced cell apoptosis and, in combination with PGC-1α, impaired mitochondrial biogenesis and suppressed the expression of NRF1 and TFAM. Agr also suppressed the expression of Bcl-2 and Cleaved-Caspase-3 and increased the expression of Bax and Caspase-3. In addition, the in vivo antitumor effect and mechanism of Agr were confirmed by using a subcutaneous tumor xenograft mouse model. Conclusions: Our findings demonstrated that Agr regulates the expression of PGC-1α, thereby inducing mitochondrial dysfunction and promoting tumor cell apoptosis. This work highlights the potential of Agr as a promising therapeutic candidate in CRC.

Gelatin/Polycaprolactone Electrospun Nanofibrous Membranes: The Effect of Composition and Physicochemical Properties on Postoperative Cardiac Adhesion.

Cardiovascular diseases have become a major threat to human health. The adhesion formation is an inevitable pathophysiological event after cardiac surgery. We have previously shown that gelatin/polycaprolactone (GT/PCL, mass ratio 50:50) electrospun nanofibrous membranes have high potential in preventing postoperative cardiac adhesion, but the effect of GT:PCL composition on anti-adhesion efficacy was not investigated. Herein, nanofibrous membranes with different GT:PCL mass ratios of 0:100, 30:70, 50:50, and 70:30 were prepared via electrospinning. The 70:30 membrane failed to prevent postoperative cardiac adhesion, overly high GT contents significantly deteriorated the mechanical properties, which complicated the suturing during surgery and hardly maintained the structural integrity after implantation. Unexpectedly, the 0:100 membrane (no gelatin contained) could not effectively prevent either, since its large pore size allowed the penetration of numerous inflammatory cells to elicit a severe inflammatory response. Only the GT:PCL 50:50 membrane exhibited excellent mechanical properties, good biocompatibility and effective anti-cell penetration ability, which could serve as a physical barrier to prevent postoperative cardiac adhesion and might be suitable for other biomedical applications such as wound healing, guided tissue or bone regeneration.

A Serum Metabolomic Study Reveals Changes in Metabolites During the Treatment of Lung Cancer-Bearing Mice with Anlotinib.

BACKGROUND: Anlotinib is a vascular endothelial growth factor receptor tyrosine kinase inhibitor recommended for the treatment of advanced lung cancer patients after at least two previous systemic chemotherapies. Currently, many patients with lung cancer do not respond well to anlotinib treatment. Therefore, the aim of this metabolomic study was to determine the internal mechanism of anlotinib action at the molecular level and to identify the potential biomarkers and pathways associated with the therapeutic effects of anlotinib. METHODS: A total of 20 male nude mice were randomly divided into 2 groups and treated with anlotinib or physiological saline. Ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was performed to analyze the serum samples and determine the differential metabolites and pathways between anlotinib and control groups. RESULTS: We observed significant differences between the anlotinib and control groups, and 13 endogenous differential metabolites and 5 potential metabolic pathways were identified. Glyoxylate and dicarboxylate metabolism, tryptophan metabolism, glycine, serine and threonine metabolism, phenylalanine metabolism and valine, leucine and isoleucine biosynthesis were the most important pathways regulated by anlotinib in vivo. Notably, these 5 differential pathways were highly associated with the TCA cycle, which is important in the proliferation and apoptosis of cancer cells. CONCLUSION: This serum metabolomic study revealed distinct metabolic profiles in lung cancer-bearing mice treated with anlotinib and identified differential metabolites and pathways between the anlotinib and control groups, which may provide new ideas for the clinical application of anlotinib.

Psychological Profiles of Chinese Patients With Hemodialysis During the Panic of Coronavirus Disease 2019.

Background: Hemodialysis patients not only suffer from somatic disorders but are also at high risks of psychiatric problems. Early this year, the outbreak of coronavirus disease 2019 (COVID-19) has caused great panic and anxiety worldwide. The impact of this acute public health event on the psychological status of hemodialysis patients and its relationship with their quality of life have not been fully investigated. Methods: This study comprised two parts. The initial study enrolled maintenance hemodialysis patients treated in Ruijin Hospital for more than 3 months from March to May 2020 during the ongoing COVID-19 pandemic. Patients completed three questionnaires including the Impact of Events Scale-Revised (IES-R), General Health Questionnaire-28 (GHQ-28), and Kidney Disease Quality of Life (KDQOL) Short Form (SF). Follow-up study was performed from December 2020 to January 2021, when the pandemic of COVID-19 has been effectively contained in China. Only patients enrolled in the initial study were approached to participate in the follow-up study. Results: There were 273 maintenance dialysis patients enrolled in the initial study and 247 finished the follow-up study. For the initial study, the estimated prevalence of nonspecific psychiatric morbidity was 45.8% (125/273) by GHQ-28. By IES-R, 53/273 (19.4%) patients presented with total scores above 24 that reflected clinical concerns. We found a significant difference regarding KDQOL scores between patients with different stress response (IES-R) groups (p = 0.026). Our follow-up study showed that KDQOL and SF-36 scores were significantly improved in comparison with those in the initial study (p = 0.006 and p = 0.031, respectively). Though total scores of GHQ-28 and IES-R did not change significantly, some subscales improved with statistical significance. Furthermore, gender, education background, and duration of hemodialysis were three factors that may affect patients' mental health, quality of life, or health status while dialysis duration was the only variable that correlated with those parameters. However, these correlations were combined effects of the COVID-19 pandemic and the dialysis itself. Conclusions: We found a correlation between changes in the mental health status of dialysis patients and changes in their quality of life. These responses were also mediated by patients' psychosocial parameters. Our results urge the necessity of psychotherapeutic interventions for some patients during this event.

Effects of a Quality Improvement Program to Reduce Central Venous Catheter-Related Infections in Hemodialysis Patients.

BACKGROUND: Central catheter infections are of concern in patients on hemodialysis because of the high risk of catheter-related bloodstream infections, sepsis, and death. Adequate nursing is critical for the prevention of such infections. This study aimed to use the PDCA (plan-do-check-act) method to reduce the incidence of central venous catheter infection using management in the maintenance of central venous catheter in patients on hemodialysis, compared with routine care. METHODS: This pilot study recruited patients on hemodialysis via central venous catheterization at the Blood Purification Center of Ruijin Hospital between November 2017 and November 2018. The patients were randomized to the routine and PDCA groups. All participants received routine nursing. The PDCA group received central venous catheter management by PDCA. The incidence of central venous catheterization-related infections, nursing satisfaction, and quality of life were compared between the two groups. RESULTS: A total of 122 participants were enrolled in each group. The incidence of central catheter-related bloodstream infection, as the primary outcome, was 0.8 and 8.8 cases per 1000 catheter days in the PDCA and routine groups, respectively (P < 0.001). In addition, as the secondary outcomes, the scores of nursing satisfaction (health guidance, nursing technology, and therapeutic effects) score and quality of life (physiological, psychological, social, and environmental status) were better in the PDCA group than in the routine group (all P < 0.01). CONCLUSIONS: This pilot study suggests that the PDCA cycle model can effectively reduce the incidence of central venous catheter-related infections and improve satisfaction and quality of life in patients on hemodialysis.

COVID-19 and healthcare system in China: challenges and progression for a sustainable future.

With the ongoing COVID-19 outbreak, healthcare systems across the world have been pushed to the brink. The approach of traditional healthcare systems to disaster preparedness and prevention has demonstrated intrinsic problems, such as failure to detect early the spread of the virus, public hospitals being overwhelmed, a dire shortage of personal protective equipment, and exhaustion of healthcare workers. Consequently, this situation resulted in manpower and resource costs, leading to the widespread and exponential rise of infected cases at the early stage of the epidemic. To limit the spread of infection, the Chinese government adopted innovative, specialized, and advanced systems, including empowered Fangcang and Internet hospitals, as well as high technologies such as 5G, big data analysis, cloud computing, and artificial intelligence. The efficient use of these new forces helped China win its fight against the virus. As the rampant spread of the virus continues outside China, these new forces need to be integrated into the global healthcare system to combat the disease. Global healthcare system integrated with new forces is essential not only for COVID-19 but also for unknown infections in the future.

Investigation and Strategic Analysis of Family Barriers to Organ Donation in China.

BACKGROUND: Families play a prominent role in the eventual organ donation decision. Because the deceased cannot directly express their wishes, their families become the actual decision makers. In China, families are permitted to make decisions regarding organ donation that may not be in accordance with the wishes of the deceased family member, and objections by families are a main bottleneck in the donation process. METHODS: Face-to-face questioning was conducted with organ procurement organization coordinators. At the same time, questionnaires were distributed in 11 cities in Zhejiang Province. RESULTS: Of the respondents, 69.9% considered family consent necessary and 77.1% thought that the view of their family had a great, even decisive, influence on them to decide to become donors. If the deceased family member had registered as an organ donor, 65.2% of families decided that they would respect the wishes of the deceased person. Adult children (58.6%) were more likely to donate than parents (37.4%; χ2 = 123.009, P < .001). Those born after 2000 and after 1990 (62.5% and 52.8%, respectively) were much more likely to donate than those born after 1960 (18.1%; χ2 = 191.485, P < .001). The interviews indicated that there were high rates of donation refusals within potential donation families. Most donor families chose to make hidden donations, and the majority of donor families had a simple family structure. CONCLUSIONS: To promote organ donation, China needs to reconsider the role of families in the decision-making process. It is essential to increase organ donation awareness within the younger generation and encourage them to discuss with their families their willingness to donate.

A clinical study of Yiqi Huayu Jiedu decoction reducing the risk of postoperative gastric cancer recurrence and metastasis: Study protocol for a randomized controlled trail.

BACKGROUND: Gastric cancer is a common gastrointestinal tumor, seriously threatening human health. Radical surgery is the preferred treatment for gastric cancer. However, due to the late diagnosis and postoperative recurrence and metastasis, the prognosis is dismal. In China, traditional Chinese medicine (TCM) has been used to treat gastric cancer for many years. The purpose of this study is to explore the efficacy and safety of Yiqi Huayu Jiedu decoction in the treatment of postoperative gastric caner. METHODS/DESIGN: 226 eligibility patients altogether will be randomly allocated to the treatment group and the control group at a ratio of 1:1. After enrollment, every patients will obtain 6 months of treatment, as well as 2 years of follow-up. At the end of this study, primary outcomes including 1-year progression-free survival rate, 2-year progression-free survival rate and disease-free survival, secondary outcomes containing tumor markers, TCM syndrome points, quality of life scale, imageological examination and the safety indicators will be assessed. DISCUSSION: This study will provide the evidence-based evidence for the efficacy of Yiqi Huayu Jiedu decoction reducing the risk of postoperative gastric cancer recurrence and metastasis, which will be beneficial to form the therapeutic regimen in postoperative gastric cancer with integrated TCM and Western medicine. TRAIL REGISTRATION: ChiCTR2000032802.

ß-Asarone Increases Chemosensitivity by Inhibiting Tumor Glycolysis in Gastric Cancer.

ß-asarone is the main active ingredient of the Chinese herb Rhizoma Acori Tatarinowii, which exhibits a wide range of biological activities. It was confirmed to be an efficient cytotoxic agent against gastroenteric cancer cells. However, the exact mechanism of ß-asarone in gastric cancer (GC) remains to be elucidated. The present study showed the inhibitory effect of ß-asarone on three types of different differentiation stage GC cell lines (MGC803, SGC7901, and MKN74) in a dose-dependent manner. Meanwhile, the synergistic sensitivity of ß-asarone and cisplatin was confirmed by using the median-effect principle. Flow cytometry assay revealed that under both normoxia and CoCl2-induced hypoxia conditions, ß-asarone can induce apoptosis of GC cells, which can block GC cells in the cell cycle G2/M phase, showing obvious subdiploid peak. Moreover, the activity of lactic dehydrogenase (LDH), an enzyme that plays an important role in the final step of tumor glycolysis, was significantly decreased in GC cells following treatment with ß-asarone. Mechanistically, ß-asarone can reduce pyruvate dehydrogenase kinase (PDK) 1, phospho(p)-PDK1, PDK4, hypoxia-inducible factor 1-α (HIF1α), c-myc, STAT5, and p-STAT5 expression, which revealed how ß-asarone affects tumor glycolysis. In conclusion, the present study provided evidence in support of the hypothesis that the increase of chemotherapy sensitization by ß-asarone is associated with the inhibition of tumor glycolysis.

Clinical and prognostic significance of MYH11 in lung cancer.

Myosin heavy chain 11 (MYH11), encoded by the MYH11 gene, is a protein that participates in muscle contraction through the hydrolysis of adenosine triphosphate. Although previous studies have demonstrated that MYH11 gene expression levels are downregulated in several types of cancer, its expression levels have rarely been investigated in lung cancer. The present study aimed to explore the clinical significance and prognostic value of MYH11 expression levels in lung cancer and to further study the underlying molecular mechanisms of the function of this gene. The Oncomine database showed that the MYH11 expression levels were decreased in lung cancer compared with those noted in the normal lung tissue (P<0.05). Kaplan-Meier plotter results revealed that the decreased MYH11 expression levels were correlated with poor prognosis in lung cancer patients. Among the lung cancer cases with gene alteration of MYH11, mutation was the most common of all alteration types. Coexpedia and Metascape analyses revealed that the target genes were primarily enriched in 'muscle contraction', 'contractile fiber part', 'actin cytoskeleton' and the 'adherens junction'. These results indicated that MYH11 is a potential novel drug target and prognostic indicator of lung cancer.

A clinical study of traditional Chinese medicine prolonging the survival of advanced gastric cancer patients by regulating the immunosuppressive cell population: A study protocol for a multicenter, randomized controlled trail.

BACKGROUND: Gastric cancer (GC) is a common high-mortality disease, causing a serious social burden. Traditional Chinese medicine has been utilized to prevent and treat GC for many years but its effects remain unclear. The aim of our study is to elucidate the anti-tumor effects and the possible mechanism of Jianpi Yangzheng Xiaozheng decoction. METHODS/DESIGN: This is a prospective, multicenter, randomized controlled trial continuing 1.5 years. Two hundred ten eligible patients will be randomly divided into 2 groups, the chemotherapy alone and the chemotherapy combined with JPYZXZ group at a ratio of 1:2. All patients will receive the treatment for 24 weeks and follow up for 1.5 years. The primary outcomes are one-year survival rate, progression-free survival, and overall survival (OS), while the secondary outcomes are immune related hematology test, objective response rate, tumor makers, traditional Chinese medicine syndrome points, fatigue scale, and quality of life scale. All of these outcomes will be analyzed at the end of the trail. DISCUSSION: This study will provide the objective evidence for the efficacy and safety of Jianpi Yangzheng Xiaozheng decoction in advanced GC. Furthermore, it will be helpful to form a therapeutic regimen in advanced GC by the combination of traditional medicine and western medicine.Trail registration: ChiCTR1900028147.

Genome-wide identification and expression analysis of citrus fruitlet abscission-related polygalacturonase genes.

Polygalacturonases (PGs) encoded by a relatively large gene family are involved in plant organ abscission, but few data is available in citrus. Here, to explore the role of PGs in citrus fruitlet abscission (CFA), we have obtained 38 citrus PG (CitPG) members, based on the citrus genome sequences. The ORF length varied from 378 to 2418 bp, encoding proteins with theoretical pI and molecular mass ranging from 4.83 to 9.92 and from 13,951.71 to 85,542.28, respectively. Most CitPGs contained no less than 3 introns, suggesting a high probability of alternative splicing. Phylogenetic tree revealed that all PGs could be divided into three groups, in which 9 CitPGs, including CitPG2, CitPG3, CitPG10, CitPG24, CitPG27, CitPG29, CitPG30, CitPG33 and CitPG34 possessed a close relationship with abscission-associated PGs, indicating their role in CFA. Expression analysis further demonstrated that CitPG2, CitPG29 and CitPG34 might be involved in CFA, the expression levels of which could be induced by ethylene, inhibited by IAA and increased during CFA. The findings in this study have provided a foundation for future studies to elucidate the roles of CitPGs in CFA.

The molecular events of IAA inhibiting citrus fruitlet abscission revealed by digital gene expression profiling.

Citrus fruits possess two abscission zones (AZ), AZ A and AZ C located at the pedicel and calyx, respectively. Early citrus fruitlet abscission (CFA) exclusively occurs at AZ A. Previous data have shown that indole-3-acetic acid (IAA) could inhibit fruitlet abscission. However, its role in CFA remains vague. In this study, we first removed the ovaries of fruitlets in order to exclude their interferences. Then, the calyxes were treated with IAA, gibberellin 3 (GA3) and 6-benzylaminopurine (6-BA), respectively. The results have shown that IAA could prevent CFA from taking place, while either GA3 or 6-BA could not. When IAA concentration decreased to a value between 30 mg/L and 40 mg/L, CFA occurred, showing a concentration-dependent manner. Digital gene expression analysis revealed that 2317 corresponded to IAA treatment, of which 1226 genes were closely related to CFA. The most affected genes included those related to biosynthesis, transport and signaling of phytohormones, primarily ethylene (ET), abscisic acid (ABA) and auxin as well as protein ubiquitination, ROS response, calcium signal transduction, cell wall and transcription factors (TFs). The results obtained in this study suggested that the IAA in AZ A could suppress ethylene biosynthesis and signaling, and then inhibit abscission signaling. To our knowledge, it is the first time to reveal the key role of IAA in CFA, which will contribute to a better understanding for the mechanism underlying CFA.

Effect of salt-stress on gene expression in citrus roots revealed by RNA-seq.

Citrus, as one of the most economically important fruits worldwide, is adversely affected by salinity stress. However, its molecular mechanisms underlying salinity tolerance are still not clear. In this study, next-generation RNA-seq technology was applied to analyze the gene expression profiling of citrus roots at 3 time points over a 24-h period of salt treatment. A total of 1831 differentially expressed genes (DEGs) were identified. Among them, 1195 and 1090 DEGs were found at 4 and 24 h, of which 454 were overlapped. Based on functional annotation, the salt overly sensitive (SOS) and reactive oxygen species (ROS) signaling pathways were found to be involved. Meanwhile, we found that hormone metabolism and signaling played important roles in salt stress. In addition, a multitude of transcription factors (TFs) including WRKY, NAC, MYB, AP2/ERF, bZIP, GATA, bHLH, ZFP, SPL, CBF, and CAMTA were identified. The genes related to cell wall loosening and stiffening (xyloglucan endotransglucosylase/hydrolases, peroxidases) were also involved in salt stress. Our data not only provided a genetic resource for discovering salt tolerance-related genes, but also furthered our understanding of the molecular mechanisms underlying salt tolerance in citrus.