An auto-inducible phosphate-controlled expression system of Bacillus licheniformis.

BACKGROUND: A promoter that drives high-level, long-term expression of the target gene under substrate limited growth conditions in the absence of an artificial inducer would facilitate the efficient production of heterologous proteins at low cost. A novel phosphate-regulated expression system was constructed using the promoter of the phytase encoding gene phyL from Bacillus licheniformis for the overexpression of proteins in this industrially relevant host. RESULTS: It is shown that the phyL promoter enables a strong overexpression of the heterologous genes amyE and xynA in B. licheniformis when cells were subjected to phosphate limitation. Whether B. licheniformis can use phytate as an alternative phosphate source and how this substrate influences the PphyL controlled gene expression under growth conditions with limited inorganic phosphate concentrations were also investigated. It is shown that B. licheniformis cells are able to use sodium phytate as alternative phosphate source. The addition of small amounts of sodium phytate (≤ 5 mM) to the growth medium resulted in a strong induction and overexpression of both model genes in B. licheniformis cells under phosphate limited growth conditions. CONCLUSIONS: The PphyL controlled expression of the investigated heterologous genes in B. licheniformis is strongly auto-induced under phosphate limited conditions. The proposed PphyL expression system enables an overexpression of target genes in B. licheniformis under growth conditions, which can be easily performed in a fed-batch fermentation process.

Ante-, Peri-, and Neonatal Factors Associated with Autism Spectrum Disorders in Vietnam: A Population-Based Cross-Sectional Survey.

Background: Autism Spectrum Disorders (ASDs) are common behavioral syndromes but limited critical evidence in Vietnam. This study aimed to identify ante-, peri- and neonatal factors for ASDs amongst children in Vietnam. Methods: This population-based study applied the cross-sectional design with a multistage sampling in 21 urban and rural districts in seven cities/provinces in Vietnam during 2017-2018. Overall, 42,551 children age 18 to 30 months were enrolled in the study. Two phases of assessment using Modified Checklist for Autism in Toddlers (M-CHAT) for screening and diagnostic assessment using Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for confirmation. We employed univariate and binary logistic regression to identify. Results: Our study showed a fast-growing trend of ASDs amongst children age 18 and 30 months (75.8 per 10,000 individuals). Nine ante-, peri-, and neonatal factors were associated with ASDs: five factors of antenatal period (history of miscarriage/abortion or stillbirth, children conceived by assisted reproduction technologies, having cold, flu or acquiring virus during pregnancy, having gestational diabetes, toxemia, high blood pressure or pre-eclampsia during pregnancy, and having stress or mental disorders during pregnancy); one factors of perinatal period (mode of delivery); and three factors of neonatal period (jaundice, respiratory distress, and newborn seizures). Conclusion: This first large-scale survey in Vietnam confirms some prenatal, perinatal, and postnatal factors with ASDs amongst children age 18 and 30 months. Future interventions should focus on these factors to early diagnosis and intervention to improve functional outcomes for risky children.

Lead Environmental Pollution and Childhood Lead Poisoning at Ban Thi Commune, Bac Kan Province, Vietnam.

Lead poisoning is a public health problem in many areas of the world. Children are at particularly high risk for adverse effects of lead exposure; even at low concentrations, lead can affect physical, mental, and behavioral development. Children living near lead-zinc mines are at high risk for environmental lead poisoning, especially the contaminated soil. We conducted a cross-sectional descriptive study in Ban Thi Commune, northern Vietnam. 195 children (92,9% participation) aged 3-14 years old (average: 7.69 ± 2.90) were randomly selected from a list of all children prepared by the village health collaborators. 109 (55.90%) were boys and 86 (44.10%) were girls. The research measures were the lead concentration in native soil and the children's total blood lead concentration determined by the inductively coupled plasma-mass spectrometry (ICP-MS) method. The results showed that lead content in soil was many times higher than American Environmental Protection Agency and Vietnam standards (average 2980.23 ± 6092.84 mg/kg dry weight of soil (range 80.05 - 33820.62)). Average blood lead levels for children were 15.42 ± 6.45 µg/dL (95% CI: 14.50 -16.33 µg/dL). The percentage of children with lead levels >10 µg/dL (value considered to be lead poisoning for children according to the Ministry of Health of Vietnam) was 79.49% of the total number of children. None of the children in this study had blood lead level (BLL) that required chelation treatment according to Vietnam MOH guideline (BLL ≥45 µg/dL). There is weakly evidence that lead exposure relates to the physical development of children. Children with low lead concentrations (less than 10 µg/dL) had height and weight of 1.47-3.51 cm and 1.19-2.81 kg, greater than those with BLL >10 µg/dL (p>0.05).