Transgenic Expression of Human C-Type Lectin Protein CLEC18A Reduces Dengue Virus Type 2 Infectivity in Aedes aegypti

The C-type lectins, one family of lectins featuring carbohydrate binding domains which participate in a variety of bioprocesses in both humans and mosquitoes, including immune response, are known to target DENV. A human C-type lectin protein CLEC18A in particular shows extensive glycan binding abilities and correlates with type-I interferon expression, making CLEC18A a potential player in innate immune responses to DENV infection; this potential may provide additional regulatory point in improving mosquito immunity. Here, we established for the first time a transgenic Aedes aegypti line that expresses human CLEC18A. This expression enhanced the Toll immune pathway responses to DENV infection. Furthermore, viral genome and virus titers were reduced by 70% in the midgut of transgenic mosquitoes. We found significant changes in the composition of the midgut microbiome in CLEC18A expressing mosquitoes, which may result from the Toll pathway enhancement and contribute to DENV inhibition. Transgenic mosquito lines offer a compelling option for studying DENV pathogenesis, and our analyses indicate that modifying the mosquito immune system via expression of a human immune gene can significantly reduce DENV infection.

Releasing Intracellular NS1 from Mosquito Cells for the Detection of Dengue Virus-Infected Mosquitoes

Dengue virus (DENV), the pathogen that causes dengue fever, is mainly transmitted by Aedes aegypti. Surveillance of infected mosquitoes is a major component of integrated mosquito control methods for reducing the risk of vector-born disease outbreaks. However, a specialized rapid test for DENV detection in mosquitoes is not currently available. Utilizing immunoblotting, we found that the secretion of NS1 from both a DENV-infected mosquito cell line and mosquito bodies was below the detection threshold. However, when Triton X-100 was used to lyse infected mosquitoes, intracellular NS1 was released, and could then be effectively detected by the NS1 rapid test. The distribution of DENV NS1 in intrathoracically infected mosquitoes was different from that of orally infected mosquitoes. Next, we performed sensitivity tests by bisecting mosquitoes longitudinally; one half of each mosquito was subjected to the NS1 rapid test while the other half was used for qPCR confirmation. This modified test had a sensitivity of nearly 90% from five days post-infection onwards, while DENV had escaped from the midgut barrier. This adapted test offers a valuable, easy-to-use tool for mosquito surveillance, which is a crucial component of DENV disease control.

Performance of the BL03U beamline at SSRF

The vacuum ultraviolet beamline BL03U with a photon energy range from 7 eV upwards has been constructed at the 3.5 GeV Shanghai Synchrotron Radiation Facility. Equipped with an APPLE-Knot undulator, this beamline is dedicated to angle-resolved photoemission spectroscopy. An energy-resolving power of higher than 4.6 × 10⁴ has been achieved in the photon energy range 21.6-48 eV, which is almost the same as the theoretical estimation.

C-Type Lectins Link Immunological and Reproductive Processes in Aedes aegypti

Physiological trade-offs between mosquito immune response and reproductive capability can arise due to insufficient resource availability. C-type lectin family members may be involved in these processes. We established a GCTL-3-/- mutant Aedes aegypti using CRISPR/Cas9 to investigate the role of GCTL-3 in balancing the costs associated with immune responses to arboviral infection and reproduction. GCTL-3-/- mutants showed significantly reduced DENV-2 infection rate and gut commensal microbiota populations, as well as upregulated JAK/STAT, IMD, Toll, and AMPs immunological pathways. Mutants also had significantly shorter lifespans than controls and laid fewer eggs due to defective germ line development. dsRNA knock-down of Attacin and Gambicin, two targets of the AMPs pathway, partially rescued this reduction in reproductive capabilities. Upregulation of immune response following GCTL-3 knock-out therefore comes at a cost to reproductive fitness. Knock-out of other lectins may further improve our knowledge of the molecular and genetic mechanisms underlying reproduction-immunity trade-offs in mosquitoes.

Fe3O4/PVDF catalytic membrane treatment organic wastewater with simultaneously improved permeability, catalytic property and anti-fouling

Fe₃O₄/Polyvinylidene fluoride (PVDF) three-channel hollow fiber catalytic membrane was successfully fabricated via non-solvent induced phase inversion and used for organic wastewater degradation in this work. The effects of Fe₃O₄ nanoparticles addition on the surface and cross-section morphologies, hydrophilicity and thermal properties of the catalytic membrane were characterized by the field emission scanning electron microscopy (SEM), water contact angle and thermogravimetric analysis (TGA), respectively. The obtained catalytic membrane exhibited good hydrophilicity, a high pure water flux of 175.8 L m^-2 h^-1 and a high removal of methylene blue (up to 97.6%) with Fenton catalytic reaction. Meanwhile, the catalytic membrane shows excellent anti-fouling property due to the presence of Fenton reaction. Our results show that Fe₃O₄/PVDF three-channel hollow fiber catalytic membrane was a promising alternative for the degradation of organic contaminants.

Epidemiological analysis of the Kaohsiung city strategy for dengue fever quarantine and epidemic prevention

Background

Dengue is endemic in over 100 countries and is an important public health problem worldwide. Dengue fever is not endemic in Taiwan; the importation of dengue viruses from neighboring countries via close commercial links and air travel is considered to be the cause of local outbreaks. Therefore, efforts toward disease control have focused on preventing the importation of dengue into Taiwan. In this study, we investigated the relationships between the numbers of imported and indigenous dengue cases to test the validity of this strategy.

Methods

Data on cases of dengue fever that occurred between 2013 and 2018 were obtained from the surveillance systems of the Taiwan Center for Disease Control and Kaohsiung City Health Department. Standard epidemiological data, including the monthly numbers of indigenous and imported cases of dengue, were calculated. Potential associations between the numbers of indigenous and imported cases were investigated using correlation analyses.

Results

We identified a possible relationship between the period of disease concealment and the number of imported dengue cases, which resulted in epidemics of indigenous dengue fever within local communities. Further analysis of confirmed cases during previous epidemics in Kaohsiung City found that the risk of indigenous dengue fever may be related to the likelihood that patients with imported dengue fever will stay within local communities.

Conclusion

Given the correlations found between imported and indigenous cases of dengue fever, as well as the relationship between the disease concealment period and the risk of indigenous dengue fever, prevention of disease importation and efficient identification of dengue cases within high-risk communities remain the major priorities for disease control.

[Efficacy of minimally invasive pulmonary surfactant administration in preterm infants with neonatal respiratory distress syndrome: a multicenter clinical trial]

Objective: To explore the feasibility and safety of minimally invasive surfactant administration (MISA) in preterm neonates with respiratory distress syndrome (NRDS). Methods: In this multicenter prospective randomized controlled trial, 92 preterm infants with gestation age ≤30 weeks and diagnosed with NRDS were enrolled in 8 level Ⅲ neonatal intensive care units (NICU) in Beijing-Tianjin-Hebei Region from 1(st) July 2017 to 31(st) December 2018. They were randomly assigned to minimally invasive surfactant administration (MISA) group or endotracheal intubation surfactant administration (EISA) group according to random number generated by computer. Infants in both groups received calf pulmonary surfactant preparation at a dose of 70-100 mg/kg. The data of demography, perinatal situation, medication administration, complications, clinical outcomes in the two groups were compared with Chi-square test, Student's t-test, Mann-Whitney U test or Fisher's exact test. Results: Among the 92 preterm infants, 53 were males, 39 were females; 47 were in the MISA group (25 males), and 45 were in the EISA group (28 males). The gestational age and birth weight were (29.5±1.2) weeks and (1 271±242) g in all patients, (29.5±1.4) weeks and (1 285±256) g in the MISA group, and (29.6±0.9) weeks and (1 255±227) g in the EISA group. The duration of surfactant infusion and the length of whole procedure in the MISA group were significantly longer than that in the EISA group (60 (18, 270) s vs. 50 (30, 60) s, Z=3.009, P=0.003; 90 (60, 300) s vs. 60 (44, 270) s, Z=3.365, P=0.001). For the outcomes, the incidence of hemodynamically significant patent ductus arteriosus (hsPDA) and bronchopulmonary dysplasia (BPD) were lower in the MISA group than in the EISA group (36% (17/47) vs. 67% (30/45), χ(2)=8.556, P=0.003; 26% (12/47) vs. 47% (21/45), χ(2)=4.464, P=0.035). Conclusions: Minimally invasive surfactant administration is applicable in preterm infants ≤30 weeks gestational age with NRDS. Although the length of whole procedure is longer than route endotracheal administration, the benefit of decreasing the incidences of hsPDA and BPD outweighs this demerit.

Hepatitis C virus genotypes 1-3 infections regulate lipogenic signaling and suppress cholesterol biosynthesis in hepatocytes

BACKGROUND

Patients with different hepatitis C virus (HCV) genotype infections are associated with varying metabolic disorders. Although alteration of lipid metabolism has been confirmed as a virus-induced metabolic derangement in chronic hepatitis C patients, the impact of various HCV genotypes on hepatic cholesterol metabolism remains elusive. In this study, we thus investigated the HCV genotype-specific lipogenic and cholesterol metabolism profiles in an in vitro cell culture system.

METHODS

We first conducted HCV cell culture system (HCVcc) assays by infecting Huh7.5.1 cells with multiple infection-competent HCV strains, including the genotype 2a JFH1 and JFH1-based intergenotypic recombinants 1b and 3a. We then examined the expression levels of various lipid and cholesterol-related genes.

RESULTS

The data showed that infection with individual HCV genotypes exerted unique gene expression regulatory effects on lipoproteins and cholesterol metabolism genes. Of note, all HCV strains suppressed cholesterol biosynthesis in hepatocytes through downregulating the expression of HMG-CoA reductase (HMGCR) and farnesyl-diphosphate farnesyltransferase 1 (FDFT1) - two essential enzymes for cholesterol biosynthesis. These HCV-mediated inhibitory effects could be reversed by treatment with sofosbuvir, a pangenotypic NS5B inhibitor. In addition, overexpression of HCV genotype 1b, 2a or 3a core protein significantly suppressed HMGCR mRNA transcription and translation, thus diminished cellular cholesterol biosynthesis. Nonetheless, the core protein had no effect on FDFT1 expression.

CONCLUSION

Although HCV infection regulates host lipid metabolism in a genotype-specific manner, its inhibition on hepatocellular cholesterogenic gene expression and total cholesterol biosynthesis is a common effect among HCV genotype 1b, 2a and 3a.

Moringa oleifera Lam Seed Oil Augments Pentobarbital-Induced Sleeping Behaviors in Mice via GABAergic Systems

Moringa oleifera Lam. (MO), which is widely consumed as both food and herbal medicine in tropical and subtropical regions, has a wide spectrum of health benefits. Yet, whether the oil obtained from MO seeds could affect (improve) the sleep activity remains unclear. Herein, we used the locomotor activity, pentobarbital-induced sleeping, and pentetrazol-induced convulsions test to examine sedative-hypnotic effects (SHE) of MO oil (MOO) and explored the underlying mechanisms. Besides, the main components of MOO like oleic acid, β-Sitosterol, and Stigmasterol were also evaluated. The results showed that they possessed good SHE. Except for oleic acid and Stigmasterol, they could significantly elevate γ-amino butyric acid (GABA) and reduce glutamic acid (Glu) levels in the hypothalamus of mice. Moreover, SHE was blocked by picrotoxin, flumazenil, and bicuculline, except for oleic acid, which could not be antagonized by picrotoxin. Molecular mechanisms showed that MOO and β-Sitosterol significantly upregulated the amount of protein-level expression of Glu decarboxylase-65 (GAD₆₅) and α₁-subunit of GABA_A receptors in the hypothalamus of mice, not affecting GAD₆₇, γ₂ subunits. These data indicated that MOO modulates sleep architectures via activation of the GABA_A-ergic systems.

Photoemission Spectroscopic Evidence for the Dirac Nodal Line in the Monoclinic Semimetal SrAs_{3}

Topological nodal-line semimetals with exotic quantum properties are characterized by symmetry-protected line-contact bulk band crossings in the momentum space. However, in most of identified topological nodal-line compounds, these topological nontrivial nodal lines are enclosed by complicated topological trivial states at the Fermi energy (E_{F}), which would perplex their identification and hinder further applications. Utilizing angle-resolved photoemission spectroscopy and first-principles calculations, we provide compelling evidence for the existence of Dirac nodal-line fermions in the monoclinic semimetal SrAs_{3}, which possesses a simple nodal loop in the vicinity of E_{F} without the distraction from complicated trivial Fermi surfaces. Our calculations revealed that two bands with opposite parities were inverted around Y near E_{F}, resulting in the single nodal loop at the Γ-Y-S plane with a negligible spin-orbit coupling effect. The band crossings were tracked experimentally and the complete nodal loop was identified quantitatively, which provide a critical experimental support for the existence of nodal-line fermions in the CaP_{3} family of materials. Hosting simple topological nontrivial bulk electronic states around E_{F} and without complication from the trivial states, SrAs_{3} is expected to be a potential platform for topological quantum state investigation and applications.

A novel gross deletion and breakpoint junction sequence analysis of ATP7B in a Chinese family with Wilson disease using next‑generation sequencing and Sanger sequencing

Wilson disease (WD) is a rare autosomal recessive genetic disorder that causes abnormal copper metabolism, resulting in pathological accumulation of copper in the liver, brain and other organs. Mutations in the ATPase copper transporter 7B (ATP7B) gene, which encodes a membrane P-type adenosine triphosphatase, have been identified as being responsible for WD. The present study analyzed clinical data and collected DNA samples from a pediatric patient with WD and her healthy parents. Mutation screening for ATP7B was performed using direct sequencing, multiplex ligation-dependent probe amplification(MLPA), next-generation sequencing (NGS) and Sanger sequencing of the breakpoint junction sequence. The patient (age, 2.7 years) presented with early-onset hepatic disease. The present study identified compound heterozygous mutations of ATP7B, including a heterozygous mutation (p.Arg1,041Trp) and a novel heterozygous gross deletion of a 57,771 bp fragment (chr13: 52490972-52548742) (GRCh37) from partial exon2- exon21 to external ATP7B sequence (15.833bp) in the patient. Analysis of the family members of the patient showed that the missense mutation and the gross deletion mutation were inherited from her mother and father, respectively. Microhomology and inverted repeat sequences, which may mediate the deletion mutation, were identified through sequence analysis on both sides of the breakpoints of this deletion. The present study provided additional information on the genotypic spectrum of the ATP7B gene, particularly with regard to early onset hepatic disease, as observed in the present patient with WD. The identification of the precise breakpoint junction sequence warrants further investigation of DNA break and recombination mechanisms. In detecting precise deletions, the NGS associated with Sanger sequencing of breakpoint junction sequence have been found to have more advantages than MLPA.

A fully automated sample-to-answer PCR system for easy and sensitive detection of dengue virus in human serum and mosquitos

BACKGROUND

The insulated isothermal PCR (iiPCR) technology enables consistent PCR amplification and detection in a simple heating device. A pan-dengue virus (DENV) RT-iiPCR, targeting the 5' untranslated region, was validated previously on the semi-automated POCKIT combo system (involving separate devices for nucleic acid extraction and PCR amplification/detection) to offer performance comparable to a laboratory real-time PCR. Working on the same technologies, a compact automated sample-in-answer-out system (POCKIT Central Nucleic Acid Analyser) has been available commercially for iiPCR, minimizing human error risks and allowing easy molecular bio-detection near points of need. Here, we evaluated the analytical and clinical performance of the pan-DENV RT-iiPCR on the fully automated system by comparison to those on the semi-automated system.

METHODOLOGY/PRINCIPAL FINDINGS

Testing sera containing serial diluted DENV-1, -2, -3, or -4 cell culture stock, the pan-DENV RT-iiPCR system had similar 100% detection endpoints on the two systems; i.e. at 1, 10, 1 and 10 PFU/ml, respectively, on the fully automated system, and at 10, 1, 10 and 10 PFU/ml, respectively, on the semi-automated system. Furthermore, both fully automated and semi-automated PCR system can detect all four DENV serotypes in mosquitos. Clinical performance of the reagent on the two systems was evaluated by testing 60 human serum samples. Both systems detected the same 40 samples (ten DENV-1, -2, -3, and -4 positive each) and did not detect the other 20; 100% agreement (κ = 1) was found between the two systems.

CONCLUSIONS/SIGNIFICANCE

With performance comparable to a previously validated system, the fully-automated PCR system allows applications of the pan-DENV reagent as a useful tool near points of need to facilitate easy, fast and effective detection of dengue virus and help mitigate versatile public health challenges in the control and management of dengue disease.

Quantitative assessment of the effects of human activities on phytoplankton communities in lakes and reservoirs

Global algal blooms have been severely threatening safety of drinking water and development of socio-economy. Effective prevention and accurate control of algal blooms require a quantitative assessment of the influence of human activities and identification of priority areas. However, previous studies on the quantitative assessment of the effects of human activities on algal communities are lacking, severely hindering the effective and precise control of algal blooms. This paper proposes a quantitative assessment model to evaluate the impact intensity of human activities on phytoplankton. Applications showed that the proliferation of phytoplankton were more limited by nutrients such as total phosphorus and ammonia where waters are less influenced by human activities, yet were less limited by these nutrients where there are highly intensive human activities. The density of phytoplankton in waters increased with an increase in human activity intensity, particularly in concentrated agricultural areas, which are priority areas for the prevention and control of algal blooms. The methodologies can clearly identify key areas for algal bloom prevention and control and can provide scientific evidence for water and nutrient management throughout the world, reducing the risk of algal blooms and ensuring aquatic ecosystem health and potable water safety.

An RT-PCR panel for rapid serotyping of dengue virus serotypes 1 to 4 in human serum and mosquito on a field-deployable PCR system

Background

Dengue fever, a mosquito-borne disease, is caused by dengue virus (DENV) which includes four major serotypes (DENV-1, -2, -3, and -4). Some serotypes cause more severe diseases than the other; severe dengue is associated with secondary infections by a different serotype. Timely serotyping can provide early warning of dengue epidemics to improve management of patients and outbreaks. A mobile insulated isothermal PCR (iiPCR) system is available to allow molecular detection of pathogens near points of need.

Methodology/Principle findings

In this study, side-by-side comparison with the CDC DENV-1-4 Real Time RT-PCR (qRT-PCR) was performed to evaluate the performance of four singleplex DENV-1–4 serotyping reverse transcription-iiPCR (RT-iiPCR) reagents for DENV subtyping on the mobile PCR system. The four RT-iiPCRs did not react with Zika virus and chikungunya virus; tests with serial dilutions of the four DENV serotypes made in human serum showed they had detection endpoints comparable to those of the reference method, indicating great analytical sensitivity and specificity. Clinical performance of the RT-iiPCR reagents was evaluated by testing 40 serum samples each (around 20 target serotype-positive and 20 DENV-negative); all four reagents had high agreement (97.5–100%) with the reference qRT-PCR. Moreover, testing of mosquitoes separately infected experimentally with each serotype showed that the four reagents detected specifically their target DENV serotypes in mosquito.

Conclusions/Significance

With analytical and clinical performance comparable to the reference qRT-PCR assay, the four index RT-iiPCR reagents on the field-deployable PCR system can serve as a useful tool for DENV detection near points of needs.

Evaluation of Vascular Remodeling in Carotid Atherosclerosis Among Type 2 Diabetes Mellitus Patients Using High-Frequency Ultrasonography Combined with Serum Resistin

Diabetes remains a long standing public health issue among the Chinese population, with an incidence of up to 11.6%, of which type 2 diabetes mellitus (T2DM) accounts for 85%-95%. During this study, we aimed to elucidate the value of high-frequency ultrasonography (HFUS) combined with serum resistin on vascular remodeling (VR) in carotid atherosclerosis (CA) among patients suffering from T2DM. A total of 432 T2DM were recruited and assigned into the short T2DM duration group (<5 years), middle T2DM duration group (5~10 years) and long T2DM duration group (>10 years), while another 172 healthy cases were recruited as the control group. The intima-media thickness (IMT) as well as plaque score, detection rate and type were detected by the HFUS. The respective blood pressure readings were measured and pulse pressure was calculated accordingly. The serum resistin level, remodeling incidence and type, levels of total cholesterol (TC), fasting blood glucose (FBG), low-density lipoprotein cholesterol (LDL-C), high-density liproprotein cholesterol (HDL-C), and triglyceride (TG) were measured. The correlation between IMT, the plaque detection rate and blood pressure were analyzed. A receiver operating characteristic (ROC) curve was constructed in order to evaluate the impact of VR in CA on T2DM patients who were solely using HFUS and serum resistin respectively, as well as a combination of HFUS with serum resistin. As In comparison with the control group, the short, middle and long T2DM duration groups all displayed increased IMT, plaque score and detection rate, serum resistin level and VR incidence, especially for the long T2DM duration group. Levels of TC, TG, FBG and LDL-C were much higher while HDL-C was lower among patients with T2DM than those in the control group. A positive correlation was detected between the disease course and IMT. The detection rate of plaque with thickening IMT exhibited upregulated levels when compared to those with normal IMT. The HFUS, serum resistin and HFUS combined with serum resistin respective areas under the ROC curve were 0.873, 0.867 and 0.923, respectively, suggesting that the combination of HFUS and serum resistin was superior to that of individual HFUS or individual serum resistin in regard to the impact of VR in CA on T2DM patients. The results of this study revealed that the combination of HFUS and serum resistin was superior to individual HFUS or individual serum resistin in relation to its ability to evaluate the impact of VR in CA in patients with T2DM.

SPHK2 protein expression, Ki-67 index and infiltration of tumor-associated macrophages (TAMs) in human glioma

INTRODUCTION

Sphingosine kinases (SPHKs), the Ki-67 index and tumor-associated macrophages (TAMs) are associated with diverse human malignancies, including glioma. SPHK2, a subtype of SPHKs, has not been assessed in glioma or correlated with the Ki-67 index or TAM infiltration. We tested the hypothesis that expression of SPHK2 correlates with the Ki-67 index and TAM infiltration in patients with glioma.

MATERIALS AND METHOD

Western blot analysis was performed on protein lysates prepared from human astrocyte (HA) and glioma cell lines. Immunofluorescence was used to determine the subcellular location of SPHK2 protein in glioma cells. Next, immunohistochemistry was employed to analyze the correlations among SPHK2, Ki-67, CD68, and CD206 in 11 non-neoplastic brain tissues and 60 glioma tissues. All slides were evaluated under ×400 magnification, and the ratio of positively stained cells to the total number of cells was calculated for analysis.

RESULTS

SPHK2, CD68 and CD206 were all increased in glioma tissues compared to non-neoplastic brain tissues, but there were no differences between WHO grades of glioma. Ki-67 was highest in WHO grade IV tumors and lowest in non-neoplastic brain tissues, and all between-group differences were statistically significant. Moreover, SPHK2 expression was positively correlated with the Ki-67, CD68 and CD206 indexes. Finally, the CD68 and CD206 indexes were both associated with the Ki-67 index.

CONCLUSION

SPHK2 protein expression, the Ki-67 index and TAM infiltration in human glioma tissue were reported in this study for the first time. SPHK2 was positively associated with TAM infiltration and glioma proliferation. Mechanistically, SPHK2 may promote glioma growth by stimulating TAMs to polarize M2-type macrophages.

Schinzel-Giedion syndrome: a novel case, review and revised diagnostic criteria

Schinzel-Giedion syndrome (SGS) is a rare autosomal dominant inheritance disorder. Heterozygous de novo mutations in the SETBP1 gene have been identified as the genetic cause of SGS. Here, we report a novel case with the syndrome with a novel insertion mutation in SETBP1. We also present a review of SGS cases, and first revise diagnostic criteria of SGS based on clinicalfindings and/or SETBP1 mutation worldwide. A revised diagnostic criteria and typing of SGS can be determined. Type I (complex and classic type) SGS patients present a development delay and typical facial features (prominent forehead, midface retraction, and short and upturned nose) associated with hydronephrosis or two of the characteristic skeletal anomalies (a sclerotic skull base, wideoccipital synchondrosis, increased cortical density or thickness, and broad ribs). Type II (middle type) patients show development delay and the distinctive facial phenotype (midface retraction, short and upturned nose), lacking both hydronephrosis and typical skeletal abnormalities, with existence of SETBP1mutation. Type III (simple type) patients with SETBP1 alteration show their major symptom is development delay, in which expressive language delay is the most striking feature. Central nervous system involvement with development delay in which expressive language delay is much more obviously affected is the most prominent feature of SGS. There is another indication that severity of phenotype of SGS may be inversely correlated with degree of SETBP1 alteration, besides gain-of-function or dominant-negative effects in SETBP1 alteration causing SGS.

A high-capacity and long-life aqueous rechargeable zinc battery using a porous metal–organic coordination polymer nanosheet cathode

Aqueous zinc ion batteries (AZIBs) have received increasing attention because of their low cost, environmental benefits and material abundance.

Fungal Denitrification Activity in Vertical Flow Constructed Wetlands as Impacted by Plant Species Richness, Carbon, Nitrogen and pH Amendments

To control potential fungal denitrification rate (PFDR) in vertical flow simulated wetlands (VFSW) microcosms, thirty VFSW microcosms were established and planted with three plant species richness levels (i.e. unplanted, monoculture, and four-species polyculture treatment), and effects of carbon, nitrogen and pH amendments on the PFDR were investigated using a room-incubating method. Among seven carbon compounds, sodium citrate, glycerol, glucose and sodium succinate were more effective in enhancing PFDRs. These enhanced effects were dependant on a given species richness level. Sodium nitrite mostly stimulated PFDRs to a greater extent than the other three nitrogen compound amendments at any richness level. Treatments with pH 5.6 or 8.4 had significantly greater PFDRs than the treatment with pH 2.8 in the three species richness levels. However, no effect of plant species richness on the PFDR was observed among any carbon, nitrogen and pH amendments. Current results suggest carbon, nitrogen and pH factors should be considered when mediating fungal denitrification in VFSW microcosms.