Improved expression and purification of highly-active 3 chymotrypsin-like protease from SARS-CoV-2.

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is the causative pathogen of coronavirus disease-19 (COVID-19). The COVID-19 pandemic has resulted in millions of deaths and widespread socio-economic damage worldwide. Therefore, numerous studies have been conducted to identify effective measures to control the spreading of the virus. Among various potential targets, the 3 chymotrypsin-like protease (3CLpro), also known as Mpro, stands out as the key protease of SARS-CoV-2, playing an essential role in virus replication and assembly, is the most prospective. In this study, we modified the commercial vector, pETM33-Nsp5-Mpro (plasmid # 156475, Addgene, USA), by inserting an autocleavage site (AVLQ) of 3CLpro and 6 × His-tag encoding sequences before and after the Nsp5-Mpro sequence, respectively. This modification enabled the expression of 3CLpro as an authentic N terminal protease (au3CLpro), which was purified to electrophoretic homogeneity by a single-step chromatography using two tandem Glutathione- and Ni-Sepharose columns. The enzyme au3CLpro demonstrated significantly higher activity (3169 RFU/min/µg protein) and catalytic efficiency (Kcat/Km of 0.007 µM-1.s-1) than that of the 3CLpro (com3CLpro) expressed from the commercial vector (pETM33-Nsp5-Mpro) with specific activity 889 RFU/min/µg and Kcat/Km of 0.0015 µM-1.s-1, respectively. Optimal conditions for au3CLpro activity included a 50 mM Tris-HCl buffer at pH 7, containing 150 mM NaCl and 0.1 mg/ml BSA at 37 °C.

Four Steroidal Saponins from the Trunks of Dracaena cambodiana with Inhibition of NO Production in LPS Activated RAW264.7 Cells.

Dracaena cambodiana Pierre ex Gagnep. is well known as a medicinal plant and widely distributed in Vietnam. Phytochemical investigation on the trunks of D. cambodiana lead to the isolation of four undescribed compounds (1-4) together with seven known ones (5-11). Their structures were determined to be pennogenin-24-yl-O-ß-D-glucopyranoside (1), 17α-hydroxycambodianoside C (2), (25R)-27-hydroxypenogenin 3-O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-glucopyranoside (3), (3ß,25R)-17α,22α-dihydroxy-furost-5-en-3-yl-O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-glucopyranoside (4), dracagenin A (5), 1-O-ß-D-glucopyranosyl-2-hydroxy-4-allylbenzene (6), 1-O-α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranosyl-2-hydroxy-allylbenzene (7), 2-O-α-L-rhamnopyranosyl-(1→6)-ß-D-glucopyranosyl-1-hydroxy-allylbenzene (8), cinnamrutinoside A (9), icariside D1 (10), and seco-isolariciresinol 9-O-ß-glucopyranoside (11) by extensive spectroscopic investigation, HR-ESI-MS, 1D and 2D NMR spectra. The anti-inflammatory activity of the isolated compounds was evaluated on macrophages. Compounds 1-6 significantly inhibited nitric oxide production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages. Among them, compound 1 showed the best inhibitory activity with an IC50 value of 8.90±0.56 µM.

Four Undescribed compounds Isolated from the Aerial Parts of Phyllanthus cochinchinensis with Antimicrobial Activity and NO Production Inhibitory Activity in LPS Activated RAW 264.7 Cells.

Four previously undescribed compounds named phyllancosides A and B (1 and 2), and phyllancochines A and B (3 and 4) together with ten known compounds (5-14) were isolated from the aerial parts of Phyllanthus cochinchinensis Spreng. Their chemical structures were elucidated on the basis of comprehensive analysis of IR, HR-ESI-MS, 1D and 2D NMR spectra. The absolute configurations of 1 and 2 were determined by electronic circular dichroism (ECD) spectra. Compounds 3, 4, and 10 showed antimicrobial activity against E. faecalis, S. aureus, and B. cereus with the MIC values in range of 32-256 µg/mL. Compound 11 inhibited E. faecalis and B. cereus, and 7 inhibited S. aureus with the MIC values in range of 64-128 µg/mL. In addition, compounds 1, 3, 4, 8, and 9 showed significantly NO production inhibitory activity in LPS activated RAW 264.7 cells with IC50 values ranging from 36.57 to 56.34 µM.

Four Unidentified Compounds Isolated from the Stem Barks of Aphanamixis polystachya and Their NO Production Inhibition in LPS Activated RAW 264.7 Cells.

Phytochemical study on the methanol extract of the stem barks of Aphanamixis polystachya led to the isolation of four previously undescribed ( 1-4) and ten known compounds (5-14). Their chemical structures were elucidated to be 11-methoxysawaranospiroride C (1), 6α,9S,10,13-tetrahydroxymegastigmane-3-one (2), 11-hydroxyaphanamixin B (3), (2Z,6E,13E)-2,6,13-triene-11,15-dihydroxyphytanic acid (4), cinnacasside D (5), cinnacasside E (6), vilsonol F (7), (3S,5R,6S,7E,9R)-3,5,6,9-tetrahydroxy-7-en-megastigmane (8), (3S,5R,6R,7E,9R)-3,6,9,10-tetrahydroxy-7-en-megastigmane (9), citroside A (10), threo-1-(3,4,5-trimethoxyphenyl)-1,2,3-propanetriol (11), 3,4,5-trimethoxyphenyl-1-O-ß-D-glucopyranoside (12), p-coumaric acid (13), ferulic acid (14) by HR-ESI-MS, ECD, 1D-, and 2D-NMR spectra. Compounds 1, 3, 4, and 9 showed NO production inhibitory activity in LPS activated RAW 264.7 cells with IC50 values of 42.0, 67.9, 20.5, and 78.6 µM, respectively, while the remaining compounds were inactive with IC50 values over 100 µM.

Five New Furostanol Glycosides from the Fruits of Tribulus terrestris with NO Production Inhibitory Activity.

Eight furostanol glycosides including five undescribed compounds, named tribufurostanosides A-E (1-5), and three known ones (6-8) were isolated from the fruits of Tribulus terrestris L. Their chemical structures were determined by the IR, HR-ESI-MS, 1D-, and 2D-NMR spectra. Furostanols 1-8 significantly inhibited nitric oxide production in LPS activated RAW 264.7 cells with IC50 values ranging from 14.2 to 64.7 µM, compared to that of the positive control compound, dexamethazone (IC50 13.6 µM).

Four New Steroidal Saponins from the Roots of Dracaena cambodiana with NO Production Inhibition Activity in LPS Activated RAW 264.7 Cells.

Seven steroidal saponins including three new 16,23-cyclocholestanes (1-3) and one new pregane (4) were isolated from the roots of Dracaena cambodiana Pierre ex Gagnep. Their chemical structures were elucidated to be (23R,25R)-26-O-ß-D-glucopyranosyl-16,23-cyclocholesta-5,17(20)-dien-22-one-3ß,16α,26-triol-3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→3)]-ß-D-glucopyranoside (1), (23R,25R)-26-O-ß-D-glucopyranosyl-16,23-cyclocholesta-5,17,20(22)-trien-3ß,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (2), (23R,25R)-16,23-cyclocholesta-5,16,20(22)-trien-3ß,22,26-triol-3-O-α-L-rhamnopyranosyl-(1→3)-ß-D-glucopyranoside (3), 3ß-[(O-α-L-rhamnopyranosyl-(1→3)-[α-L-rhamnopyranosyl-(1→2)]-ß-D-gluco-pyranosyl)oxy]-pregna-5,17(20)-diene-16-one-20-carboxylic acid 4''''-O-ß-D-glucopyranosylisopentyl ester (4), cambodianoside A (5), diosbulbiside C (6), and diosbulbiside D (7), by IR, HR-ESI-MS, 1D and 2D NMR spectra. Compounds 1 and 4-7 inhibited nitric oxide (NO) production in lipopolysaccharide activated RAW 264.7 cells with IC50 values ranging from 19.03±1.84 to 67.92±3.81 µM, whereas compounds 2 and 3 were inactive with IC50 values over 100 µM.

Undescribed Triterpenes from the Leaves of Syzygium myrsinifolium with Their α-Glucosidase and α-Amylase Inhibition Activity.

Two undescribed triterpenes, syzyfolium A (1) and syzyfolium B (2), together with twelve known compounds, terminolic acid (3), actinidic acid (4), piscidinol A (5), threo-dihydroxydehydrodiconiferyl alcohol (6), lariciresinol-4-O-ß-D-glucoside (7), icariol A2 (8), 14ß,15ß-dihydroxyklaineanone (9), garcimangosone D (10), (+)-catechin (11), myricetin-3-O-α-L-rhamnopyranoside (12), quercitrin (13), and 3, 4, 5-trimethoxyphenyl-(6'-O-galloyl)-O-ß-D-glucopyranoside (14) were isolated from the leaves of Syzygium myrsinifolium. Their chemical structures were determined by IR, HR-ESI-MS, 1D and 2D NMR spectra. Compounds 3 and 4 inhibited significantly α-glucosidase with IC50 values of 23.99 and 36.84, respectively, and compounds 1 and 2 inhibited significantly α-amylase with IC50 values of 35.48 and 43.65 µM, respectively.

High Human T-Cell Leukemia Virus Type 1c Proviral Loads Are Associated With Diabetes and Chronic Kidney Disease: Results of a Cross-Sectional Community Survey in Central Australia.

BACKGROUND: A link between chronic inflammation and several noncommunicable diseases (NCDs) has been established. Although chronic infection with the human T-cell leukemia virus type 1 (HTLV-1) is the recognized cause of several inflammatory diseases and these are associated with a high number of HTLV-1-infected cells in peripheral blood (proviral load [PVL]), possible interactions between PVL and NCDs have not been studied at a community level. METHODS: Adult Aboriginal residents of 7 remote communities were invited to complete a health survey between 25 August 2014 and 30 June 2018. Blood was drawn for HTLV-1 serology and PVL, and relevant medical conditions were obtained from health records. Associations between HTLV-1 PVL and diabetes, chronic kidney disease (CKD), and coronary artery disease (CAD) were determined using logistic regression, adjusting for available confounders. RESULTS: Among 510 participants (56% of the estimated adult resident population, 922), 197 (38.6%) were HTLV-1-infected. A high HTLV-1 PVL was associated with a 2-fold increase in the odds of diabetes and CKD (diabetes, adjusted odds ratio [aOR], 1.95; 95% confidence interval [CI], 1.06-3.61; P = .033 and CKD: aOR, 2.00; 95% CI, 1.03-3.8; P = .041). A nonsignificant association between high PVL and CAD (aOR, 7.08; 95% CI, 1.00-50.18; P = .05) was found for participants aged <50 years at the time of angiography. CONCLUSIONS: In a community-based study in central Australia, people with HTLV-1 who had high HTLV-1 PVL were more likely to have diabetes and CKD. These findings have potential clinical implications.

Effect of vitamin D supplementation on depression in older Australian adults.

OBJECTIVES: To investigate whether vitamin D supplementation reduces depressive symptoms and incidence of antidepressant use. METHODS: We used data from the D-Health Trial (N = 21,315), a randomized double-blind placebo-controlled trial of monthly vitamin D3 for the prevention of all-cause mortality. Participants were Australians aged 60-84 years. Participants completed the Patient Health Questionnaire (PHQ-9) at 1, 2 and 5 years after randomization to measure depressive symptoms; national prescribing records were used to capture antidepressant use. We used mixed models and survival models. RESULTS: Analyses of PHQ-9 scores included 20,487 participants (mean age 69·3 years, 46% women); the mean difference (MD) in PHQ-9 score (vitamin D vs. placebo) was 0·02 (95% CI -0·06, 0·11). There was negligible difference in the prevalence of clinically relevant depression (PHQ-9 score ≥10) (odds ratio 0·99; 95% CI 0·90, 1·08). We included 16,670 participants in the analyses of incident antidepressant use (mean age 69·4 years, 43% women). Incidence of antidepressant use was similar between the groups (hazard ratio [HR] 1·04; 95% CI 0·96, 1·12). In subgroup analyses, vitamin D improved PHQ-9 scores in those taking antidepressants at baseline (MD -0·25; 95% CI -0·49, -0·01; p-interaction = 0·02). It decreased risk of antidepressant use in participants with predicted 25(OH)D concentration <50 nmol/L (HR 0·88; 95% CI 0·75, 1·02; p-interaction = 0·01) and increased risk in those with predicted 25(OH)D ≥ 50 nmol/L (HR 1·10; 95% CI 1·01, 1·20). CONCLUSION: Monthly supplementation with high-dose vitamin D3 was not of benefit for measures of depression overall, but there was some evidence of benefit in subgroup analyses. CLINICAL TRIAL REGISTRATION: The trial is registered on the Australian New Zealand Clinical Trials Registry: ACTRN12613000743763. https://www.anzctr.org.au/.

New Guaiane-Type Sesquiterpene and Norsesquiterpene from Alisma plantago-aquatica and Their Xanthine Oxidase Inhibitory Activity.

A new sesquiterpene (1) and a new norsesquiterpene (2) belonging guaiane-type skeleton together with six known compounds (3-8) were isolated from the rhizomes of Alisma plantago-aquatica. Their structures were determined by HR-ESI-MS, 1D and 2D NMR spectroscopic methods. Absolute configurations of new compounds were established by experimental and TD-DFT computational ECD spectra. Compounds 1-8 exhibited xanthine oxidase inhibitory activity with their IC50 values in range of 9.4-66.7 µM. The sesquiterpenoids 1-5 displayed the inhibitory activity and hence they could be potential xanthine oxidase inhibitors from A. plantago-aquatica.

Dimethylbutyrylated Dibenzocyclooctadiene Lignans from the Fruits of Schisandra cauliflora Inhibit NO Production in LPS-Activated RAW264.7 Cells.

From the fruits of Schisandra cauliflora, five new dimethylbutyrylated dibenzocyclooctadiene lignans, named schisandracaurins A-E, were isolated using separation and chromatographic techniques. Their structures were determined by extensive analyses of HR-ESI-MS, NMR, and ECD spectra. The schisandracaurins A-E potentially inhibited NO production in LPS-activated RAW264.7 cells with their IC50 values from 21.4 to 30.3 µM.

One new furostane saponin from Allium ramosum and lipid accumulation inhibitory activity.

A new furostane saponin, ramosaponin (1), and four known furostane saponins, protodioscin (2), dehydrotomatoside (3), (25 R)-26-O-(ß-D-glucopyranosyl)-furost-5-ene-3ß,22α,26-triol 3-O-ß-D-glucopyranosyl-(1→4)-ß-D-galactopyranoside (4), and anguivioside A (5) were isolated from the methanol extract of Allium ramosum seeds. Their structures were identified based on spectroscopic evidence and comparison with those reported in the literature. All compounds were evaluated for reduction of lipid accumulation in HepG2 cell line. As a result, compound 1 showed significant lipid accumulation inhibitory activity with an IC50 value of 64.32 ± 3.87 µM.

Three new chromanes and one new flavone C-glycoside from Mallotus apelta.

Three new chromanes, malloapeltas J-L (1-3), and one new flavone C-glycoside, malloflavoside (4), together with four known compounds, apigenin 6-C-ß-D-xylopyranosyl-8-C-α-L-arabinopyranoside (5), apigenin 6-C-ß-D-glucopyranosyl-8-C-α-L-arabinopyranoside (6), apigenin 7-O-ß-D-apiofuranosyl-(1→2)-ß-D-glucopyranoside (7), and acantrifoside E (8) were isolated from the methanol extract of the leaves of Mallotus apelta. Their chemical structures were determined using spectroscopic methods, including 1D, 2D NMR, and HR-ESI-MS methods. All the isolated compounds were evaluated their cytotoxic activity against human prostate cancer (PC-3) and human breast cancer (MCF-7) cells, but none of them showed cytotoxicities on both human cancer cell lines.

Bayesian merging of numerical modeling and remote sensing for saltwater intrusion quantification in the Vietnamese Mekong Delta.

Saltwater intrusion has become one of the most concerning issues in the Vietnamese Mekong Delta (VMD) due to its increasing impacts on agriculture and food security of Vietnam. Reliable estimation of salinity plays a crucial role to mitigate the impacts of saltwater intrusion. This study developed a hybrid technique that merges satellite imagery with numerical simulations to improve the estimation of salinity in the VMD. The salinity derived from Landsat images and by numerical simulations was fused using the Bayesian inference technique. The results indicate that our technique significantly reduces the uncertainties and improves the accuracy of salinity estimates. The Nash-Sutcliffe coefficient is 0.74, which is much higher than that of numerical simulation (0.63) and Landsat estimation (0.6). The correlation coefficient between the ensemble and measured salinity is relatively high (0.88). The variance of the ensemble salinity errors (5.0 ppt2) is lower than that of Landsat estimation (10.4 ppt2) and numerical simulations (9.6 ppt2). The proposed approach shows a great potential to combine multiple data sources of a variable of interest to improve its accuracy and reliability wherever these data are available.

Vitamin D Supplementation and Antibiotic Use in Older Australian Adults: An Analysis of Data From the D-Health Trial.

BACKGROUND: Vitamin D supplementation may reduce the risk or severity of infection, but this has been investigated in few large population-based trials. We analyzed data from the D-Health Trial, using prescription of antibiotics as a surrogate for infection. METHODS: The D-Health Trial is a randomized, double-blind, placebo-controlled trial in which 21 315 Australians aged 60-84 years were randomized to 60 000 IU of supplementary vitamin D3 or placebo monthly for 5 years. For this analysis, the primary outcome was the number of antibiotic prescription episodes; secondary outcomes were total number of prescriptions, repeat prescription episodes, and antibiotics for urinary tract infection. We estimated incidence rate ratios (IRRs) using negative binomial regression, and odds ratios using logistic regression. RESULTS: Vitamin D supplementation slightly reduced the number of prescription episodes (IRR, 0.98; 95% confidence interval [CI], .95-1.01), total prescriptions (IRR, 0.97; 95% CI, .93-1.00), and repeat prescription episodes (IRR, 0.96; 95% CI, .93-1.00). There was stronger evidence of benefit in people predicted to have insufficient vitamin D at baseline (prescription episodes IRR, 0.93; 95% CI, .87-.99). CONCLUSIONS: Vitamin D may reduce the number of antibiotic prescriptions, particularly in people with low vitamin D status. This supports the hypothesis that vitamin D has a clinically relevant effect on the immune system. CLINICAL TRIALS REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12613000743763. https://www.anzctr.org.au/.

The effect of vitamin D supplementation on risk of keratinocyte cancer: an exploratory analysis of the D-Health randomized controlled trial.

BACKGROUND: Vitamin D may play a role in prevention of keratinocyte cancer (KC), but observational studies examining the association between serum 25-hydroxy vitamin D concentration and KC are largely uninformative because sun exposure causes both KC and vitamin D production. There is scant evidence from clinical trials of supplementary vitamin D. OBJECTIVES: To examine the effect of vitamin D supplementation on the risk of developing KC. METHODS: We used data from the D-Health Trial, a randomized placebo-controlled trial of vitamin D supplementation (60 000 international units monthly for 5 years) among Australians aged ≥60 years. KC outcomes were captured through linkage to a national administrative dataset for those who consented (N = 20 334; 95%). We used negative binomial regression to analyse the incidence of KC excisions and the incidence of actinic lesions treated using cryotherapy or serial curettage, and flexible parametric survival models for analysis of time to first KC excision. RESULTS: Randomization to vitamin D supplementation did not reduce the incidence of KC lesions treated by excision [incidence rate ratio (IRR) 1·04; 95% confidence interval (CI) 0·98-1·11], the incidence of actinic lesions treated using other methods (IRR 1·01; 95% CI 0·95-1·08) or time to first histologically confirmed KC excision (hazard ratio 1·02; 95% CI 0·97-1·08). However, in subgroup analysis vitamin D increased the incidence of KC excisions in adults aged ≥ 70 years (IRR 1·13, 95% CI 1·04-1·23; P-value for interaction = 0·01). CONCLUSIONS: Vitamin D supplementation did not reduce the incidence of KC or other actinic lesions. What is already known about this topic? Laboratory studies have suggested possible protective effects of vitamin D on skin cancer. Observational studies investigating the association between vitamin D and risk of keratinocyte cancer are largely uninformative as ultraviolet radiation both causes skin cancer and is the primary source of vitamin D. The evidence from randomized controlled trials of vitamin D is limited and inconclusive. What does this study add? This population-based, randomized controlled trial suggests that supplementing older adults with a high monthly dose of vitamin D for 5 years does not affect the incidence of keratinocyte cancer.

A global analysis of literature on older adults and lifelong living with HIV.

With the growing number of older people living with HIV, "What is the most effective geriatric care and the research trend of existing literature?" is a compelling question after 30 years since the first paper related to aging and HIV/AIDS published. Our study aims to apply quantitative and qualitative analysis to explore the knowledge gaps and describes the research interest of gerontology research in the field of HIV. A bibliometric analysis was conducted based on the databased of the Web of Science from 1991 to 2019. The major domains of research areas were visualized by using VOSviewer software. Latent Dirichlet Allocation (LDA) was applied to classify the dataset into topics. There was a rising number of publications about this topic over time. Our findings indicated that antiretroviral treatment and evaluating quality of life and harm reduction were the major domains regarding care for OPLWH. In addition, the finding highlights the role of social competence in treatment outcomes. Further research needs to tailor multi-disciplinary programs and flexible interventions to reduce the burden and the mortality rate of HIV/AIDS.

Structural barriers for retention of HIV/AIDS patients after initiating antiretroviral therapy in outpatient clinics of Vietnam.

Little evidence is available about structural factors associated with the retention in care for people living with HIV/AIDS (PLWH) in Vietnam. This retrospective longitudinal study was conducted among PLWH initiating antiretroviral therapy (ART) in 62 ART clinics from 15 provinces, to estimate retention rates and identify specific related structural factors. Facility-related factors such as location, duration of HIV service implantation, level of healthcare facility, frequency of drugs dispensed, integration of HIV care were examined. Cox proportional hazard model was employed to estimate the retention rate and association between facility-level factors and loss-to-follow up (LTFU). Among 20,119 patients, the retention rates after 6, 12, 24, 36 and 48 months were 96.5% (95% CI = 96.2%-96.7%), 93.6% (95% CI = 93.2%-93.9%), 90.2% (95% CI = 89.8%-90.6%), 87.9% (95% CI = 87.4%-88.4%) and 86.0% (95% CI = 85.4%-86.5%), respectively. Facility-level factors associated with increased risk of LTFU included duration of HIV service implementation, frequency of drug dispensed per month, integration of HIV care and of treatment procedures into general care, clinics at central or provincial level and in the Middle region of Vietnam. Such association should be addressed in future care planning and HIV/AIDS management to ensure greater coverage of therapy in Vietnam.

Notes on Culturable Endophytic Microorganisms Isolated from 14 Medicinal Plants in Vietnam: A Diversity Analysis to Predict the Host-Microbe Correlations.

Endophytes can generate a cornucopia of marvelous bioactive secondary metabolites useful for mankind but their biodiversity and associations with host plants are still elusive. In this study, we explored the culturable endophytic microorganisms associated with 14 medicinal plants that are of high socio-economic value and/or reportedly endemic to northern Vietnam. Specifically, we isolated the endophytic microorganisms by applying surface sterilization methods and identified them based on morphological and rDNA sequence analyses. Agglomerative Hierarchical Clustering (AHC) and Principal Component Analysis (PCA) were used to analyze the correlations between the taxonomic affiliations of the culturable endophytes and the characteristics of their hosts. Most of the culturable endophytes obtained were bacteria (80), and few of those were actinomycetes (15) and fungi (8). Many of them are reported to be endophytes of medicinal plants for the first time. A number of plants (5) are also reported for the first time to contain microbial endophytes, while some plants with powerful pharmaceutical potential harbor unique endophytes. Furthermore, our results reveal a strikingly close relation between the compositions of bacterial and fungal isolates from plants having anti-bacterial activity and those from plants having anti-inflammatory activity, or between the compositions of the microbial endophytic isolates from plants having anti-cancer activity and those from plants having antioxidant activity. Altogether, the results provide new findings which can be inspiring for further in-depth studies to explore and exploit the relationships between medicinal plants and their associated endophytes in northern Vietnam and world-wide.

Evaluation of genetic diversity and population structure in four indigenous duck breeds in Vietnam.

This study characterized genetic diversity and population structure of four indigenous Vietnamese duck breeds and an exotic breed for setting the conservation priority. A total of 200 samples from four duck breeds (Sincheng, Minhhuong, Muongchieng and Bauben) and an exotic breed (Supermeat) were genotyped for fifteen microsatellite markers. The average number of alleles per locus was 14.07. A moderate genetic diversity was observed for indigenous breeds as mean of observed and expected heterozygosity as Ho = 0.50 and He = 0.57, respectively. The Bauben had the lowest values of Ho (0.41) and He (0.48) while Sincheng had the highest values of Ho (0.6) and He (0.69), respectively. The inbreeding coefficients (FIS) ranged from 0.12 to 0.16, and all breeds were significantly under heterozygote deficit. Nei's genetic distance was the shortest between Minhhuong and Muongkhieng. The discriminant analysis of principal components of studied breeds resulted in four genetic clusters. The Minhhuong and Muongkhieng breeds joined the same genetic cluster while other breeds had their own clusters. These results indicated that the possibility to combine Minhhuong and Muongkhieng for reducing the cost of conservation and suggested that conservation of the Bauben should be prioritized to avoid inbreeding depression and genetic drift.