Two new thymol derivatives from Eupatorium fortunei.

Two new thymol derivatives (1-2) were isolated from the aerial parts of Eupatorium fortunei. Their structures were elucidated on the basis of comprehensive spectroscopic data analysis as 8,9-dehydrothymol-3-O-ß-glucoside (1), and 9-(acetyloxy)thymol-3-yl (3-methylbut-2-enoate) (2). All isolates were evaluated for cytotoxic activities with IC50 values greater than 50 µM in vitro against MCF-7, HeLa, A549, and Hep G-2 cancer cells.

Recent advances in biotechnological production of polyunsaturated fatty acids by Yarrowia lipolytica.

Owing to the important physiological functions, polyunsaturated fatty acids (PUFAs) play a vital role in protecting human health, such as preventing cancer, cardiovascular disease, and diabetes. Specifically, Yarrowia lipolytica has been identified as the most popular non-conventional oleaginous yeast, which can accumulate the abundant intracellular lipids, indicating that has great potential as an industrial host for production of PUFAs. Notably, some novel engineering strategies have been applied to endow and improve the abilities of Y. lipolytica to synthesize PUFAs, including construction and optimization of PUFAs biosynthetic pathways, improvement of preucrsors acetyl-coA and NADPH supply, inhibition of competing pathways, knockout of ß-oxidation pathways, regulation of oxidative stress defense pathways, and regulation of genes involved in upstream lipid metabolism. Besides, some bypass approaches, such as strain mating, evolutionary engineering, and computational model based on omics, also have been proposed to improve the performance of engineering strains. Generally, in this review, we summarized the recent advances in engineering strategies and bypass approaches for improving PUFAs production by Y. lipolytica. In addition, we further summarized the latest efforts of CRISPR/Cas genome editing technology in Y. lipolytica, which is aimed to provide its potential applications in PUFAs production.

Harnessing Yarrowia lipolytica Peroxisomes as a Subcellular Factory for α-Humulene Overproduction.

The sesquiterpene α-humulene has been shown to have anti-inflammatory and anticancer activities, which has led to its vast application potential in medicine. However, α-humulene production methods including phytoextraction and chemical synthesis currently were limited to low yield, high costs, and expensive catalysts, which cannot meet the increasing market demand. In this study, Yarrowia lipolytica was developed as a robust cell factory for α-humulene production. The peroxisome in Y. lipolytica was first engineered to boost the synthesis of the sesquiterpene α-humulene. By compartmentalization of the α-humulene biosynthesis pathway, improving ATP and acetyl-CoA supply, and optimizing the gene copy numbers of rate-limiting enzymes, the engineered strain GQ2012 could produce 3.2 g/L α-humulene in a 5 L bioreactor, the highest α-humulene titer reported so far. Our study provides a valuable reference for highly sustainable production of terpenoids by peroxisome engineering in Y. lipolytica.

Intra-Host Evolution of Norovirus GII.4 in a Chronic Infected Patient With Hematopoietic Stem Cell Transplantation.

Human noroviruses (NVs) are the leading cause of acute gastroenteritis outbreaks worldwide. The majority of outbreaks are caused by genogroup II.4 (GII.4), with new variants emerging every 2 to 4 years. Immunocompromised patients are hypothesized to be important reservoirs where new NV variants emerge. Here, we examined intra-host NV variants and assessed immune-driven NV evolution in chronically infected immunocompromised hosts. Three NV GII.4-positive samples were collected from the same patient in different clinical phases following allogeneic hematopoietic stem cell transplantation, and had viral RNA concentrations of 2.46 × 106, 1.47 × 106, and 2.26 × 106 genome copies/mL. The non-synonymous (dN) and synonymous (dS) substitution ratio of the sequences in the partial P domain were >1, indicating strong positive selection in the patient. Both the number and the frequency of the single nucleotide variants increased over time in the patient. Also, the majority of capsid amino acid changes were located at blocking epitopes and histo-blood group antigen (HBGA)-binding sites, and 11 positive selection sites were found in the capsid region, of which 8 sites were presented in blocking epitopes or HBGA-binding sites. Homodimeric P-domain capsid models also suggested a structural change in the epitopes and HBGA-binding sites. The results suggested that novel variants of NV GII.4 with HBGA and antigenic site changes were produced in the immunocompromised patient. Further functional and epidemiological studies are needed to determine whether the new variants are a risk to public health.

GII.13/21 Noroviruses Recognize Glycans with a Terminal ß-Galactose via an Unconventional Glycan Binding Site.

Human noroviruses (huNoVs) recognize histo-blood group antigens (HBGAs) as host susceptibility factors. GII.13 and GII.21 huNoVs form a unique genetic lineage that emerged from mainstream GII NoVs via development of a new, nonconventional glycan binding site (GBS) that binds Lea antigen. This previous finding raised the question of whether the new GII.13/21 GBS really has such a narrow glycan binding spectrum. In this study, we provide solid phenotypic and structural evidence indicating that this new GBS recognizes a group of glycans with a common terminal ß-galactose (ß-Gal). First, we found that P domain proteins of GII.13/21 huNoVs circulating at different times bound three glycans sharing a common terminal ß-Gal, including Lec, lactose, and mucin core 2. Second, we solved the crystal structures of the GII.13 P dimers in complex with Lec and mucin core 2, which showed that ß-Gal is the major binding saccharide. Third, nonfat milk and lactose blocked the GII.13/21 P domain-glycan binding, which may explain the low prevalence of GII.13/21 viruses. Our data provide new insight into the host interactions and epidemiology of huNoVs, which would help in the control and prevention of NoV-associated diseases.IMPORTANCE Evidence from both phenotypic binding assay and structural study support the observed interactions of human noroviruses (huNoVs) with histo-blood group antigens (HBGAs) as receptors or attachment factors, affecting their host susceptibility. GII.13 and GII.21 genotypes form a unique genetic lineage that differs from the mainstream GII huNoVs in their unconventional glycan binding site. Unlike the previous findings that GII.13/21 genotypes recognize only Lea antigen, we found in this study that they can interact with a group of glycans with a common terminal ß-Gal, including Lec, lactose, and mucin core 2. However, this wide glycan binding spectrum in a unique binding mode of the GII.13/21 huNoVs appears not to increase their prevalence, probably due to the existence of decoy glycan receptors in human gastrointestinal tract limiting their infection. Our findings shed light on the host interaction and epidemiology of huNoVs, which would impact the strategy of huNoV control and prevention.

Susceptibility of human tonsillar epithelial cells to enterovirus 71 with normal cytokine response.

A recent histopathologic study implicated human tonsillar crypt epithelium as an important site for EV71 replication in EV71-caused fatal cases. This study aimed to confirm the susceptibility of human tonsillar epithelium to EV71. Two human tonsillar epithelial cell lines (UT-SCC-60A and UT-SCC-60B) were susceptive to EV71, and PI3K/AKT, p38, ERK1/2, and JNK1/2 signal pathways were activated. Interferon-α, IL-8, IL-1ß, IL-6 and IL-12p40 were induced and regulated by PI3K/AKT, p38, ERK1/2, and JNK1/2 signal pathways. PI3K/AKT pathway activation appeared to suppress the induction of TNF-α, which induced cell survival by inhibiting GSK-3ß. The activation of NF-κB was observed but inhibited by these pathways in EV71 infection. Furthermore, ERK1/2 and JNK1/2 were essential for efficient EV71 replication. Human tonsillar epithelial cells support EV71 replication and display innate antiviral immunity in vitro, indicating that human tonsillar epithelial cells may be novel targets for EV71 infection and replication in vivo.