Engineering sub-organelles of a diploid Saccharomyces cerevisiae to enhance the production of 7-dehydrocholesterol.

7-Dehydrocholesterol (7-DHC) is widely present in various organisms and is an important precursor of vitamin D3. Despite significant improvements in the biosynthesis of 7-DHC, it remains insufficient to meet the industrial demands. In this study, we reported high-level production of 7-DHC in an industrial Saccharomyces cerevisiae leveraging subcellular organelles. Initially, the copy numbers of DHCR24 were increased in combination with sterol transcriptional factor engineering and rebalanced the redox power of the strain. Subsequently, the effects of compartmentalizing the post-squalene pathway in peroxisomes were validated by assembling various pathway modules in this organelle. Furthermore, several peroxisomes engineering was conducted to enhance the production of 7-DHC. Utilizing the peroxisome as a vessel for partial post-squalene pathways, the potential of yeast for 7-dehydrocholesterol production was demonstrated by achieving a 26-fold increase over the initial production level. 7-DHC titer reached 640.77 mg/L in shake flasks and 4.28 g/L in a 10 L bench-top fermentor, the highest titer ever reported. The present work lays solid foundation for large-scale and cost-effective production of 7-DHC for practical applications.

Design of in vitro biomimetic experimental system and simulation analysis for transvascular transport of nano-preparation.

Recently, the enhanced penetration and retention (EPR) effect of nano-preparations has been questioned. Whether the vascular endothelial cell gap (VECG) is the main transport pathway of nano-preparations has become a hot issue at present. Therefore, we propose an in vitro biomimetic experimental system that demonstrates the transvascular transport of nano-preparation. Based on the tumor growth process, the experimental system was used to simulate the change process of abnormal factors (vascular endothelial cell gap and interstitial fluid pressure (IFP)) in the tumor microenvironment. The influence of change in the abnormal factors on the enhanced penetration and retention effect of nano-preparation was explored, and simulation verification was performed. The results show that when the interstitial fluid pressure is close to the vascular fluid pressure (VFP), the transport of nano-preparation is obstructed, resulting in the disappearance of enhanced penetration and retention effect of the nano-preparation. This indicates that the pressure gradient between vascular fluid pressure and interstitial fluid pressure determines whether the enhanced penetration and retention effect of nano-preparations can exist.

Synthesis and Characterization of Bridging-Diazene Diiron Half-Sandwich Complexes: The Role of Sulfur Hydrogen Bonding.

We report two bridging-diazene diiron complexes [Cp*Fe(8-quinolinethiolate)]2(µ-N2H2) (1-N2H2) and [Cp*Fe(1,2-Cy2PC6H4S)]2(µ-N2H2) (2-N2H2), synthesized by the reaction of hydrazine with the corresponding thiolate-based iron half-sandwich complex, [Cp*Fe(8-quinolinethiolate)]2 (1) and Cp*Fe(1,2-Cy2PC6H4S) (2). Crystallographic analysis reveals that the thiolate sites in 1-N2H2 and 2-N2H2 can engage in N-H···S hydrogen bonding with the diazene protons. 1-N2H2 is thermally stable in both solid and solution states, allowing for one-electron oxidation to afford a cationic diazene radical complex [1-N2H2]+ at room temperature. In contrast, 2-N2H2 tends to undergo N2H2/N2 transformation, leading to the formation of a Fe(III)-H species by the loss of N2. In addition to stabilizing HN=NH species through the hydrogen bonding, the thiolate-based ligands also seem to facilitate proton-coupled electron transfer, thereby promoting N-H cleavage.

Bimetallic H2 Addition and Intramolecular Caryl-H Activation Mediated by an Iron-Zinc Hydride.

Heteronuclear Fe(µ-H)Zn hydride Cp*Fe(1,2-Cy2PC6H4)HZnEt (3) undergoes reversible intramolecular Caryl-H reductive elimination through coupling of the cyclometalated phosphinoaryl ligand and the hydride, giving rise to a formal Fe(0)-Zn(II) species. Addition of CO intercepts this equilibrium, affording Cp*(Cy2PPh)(CO)Fe-ZnEt that features a dative Fe-Zn bond. Significantly, this system achieves bimetallic H2 addition, as demonstrated by the transformation of the monohydride Fe(µ-H)Zn to a deuterated dihydride Fe-(µ-D)2-Zn upon reaction with D2.

Electrocatalytic Interconversions of CO2 and Formate on a Versatile Iron-Thiolate Platform.

Exploring bidirectional CO2/HCO2- catalysis holds significant potential in constructing integrated (photo)electrochemical formate fuel cells for energy storage and applications. Herein, we report selective CO2/HCO2- electrochemical interconversion by exploiting the flexible coordination modes and rich redox properties of a versatile iron-thiolate platform, Cp*Fe(II)L (L = 1,2-Ph2PC6H4S-). Upon oxidation, this iron complex undergoes formate binding to generate a diferric formate complex, [(L-)2Fe(III)(µ-HCO2)Fe(III)]+, which exhibits remarkable electrocatalytic performance for the HCO2--to-CO2 transformation with a maximum turnover frequency (TOFmax) ∼103 s-1 and a Faraday efficiency (FE) ∼92(±4)%. Conversely, this iron system also allows for reduction at -1.85 V (vs Fc+/0) and exhibits an impressive FE ∼93 (±3)% for the CO2-to-HCO2- conversion. Mechanism studies revealed that the HCO2--to-CO2 electrocatalysis passes through dicationic [(L2)-•Fe(III)(µ-HCO2)Fe(III)]2+ generated by unconventional oxidation of the diferric formate species taking place at ligand L, while the CO2-to-HCO2- reduction involves a critical intermediate of [Fe(II)-H]- that was independently synthesized and structurally characterized.

LAZY3 interacts with LAZY2 to regulate tiller angle by modulating shoot gravity perception in rice.

Starch biosynthesis in gravity-sensing tissues of rice shoot determines the magnitude of rice shoot gravitropism and thus tiller angle. However, the molecular mechanism underlying starch biosynthesis in rice gravity-sensing tissues is still unclear. We characterized a novel tiller angle gene LAZY3 (LA3) in rice through map-based cloning. Biochemical, molecular and genetic studies further demonstrated the essential roles of LA3 in gravity perception of rice shoot and tiller angle control. The shoot gravitropism and lateral auxin transport were defective in la3 mutant upon gravistimulation. We showed that LA3 encodes a chloroplast-localized tryptophan-rich protein associated with starch granules via Tryptophan-rich region (TRR) domain. Moreover, LA3 could interact with the starch biosynthesis regulator LA2, determining starch granule formation in shoot gravity-sensing tissues. LA3 and LA2 negatively regulate tiller angle in the same pathway acting upstream of LA1 to mediate asymmetric distribution of auxin. Our study defined LA3 as an indispensable factor of starch biosynthesis in rice gravity-sensing tissues that greatly broadens current understanding in the molecular mechanisms underlying the starch granule formation in gravity-sensing tissues, and provides new insights into the regulatory mechanism of shoot gravitropism and rice tiller angle.

Transformation of Acetylene to Ethenylidene, Carbene, Acetylide, Vinyl, and Olefin Groups with Cp*Fe(1,2-Cy2PC6H4S).

Tautomerization of C2H2 at half-sandwich compound Cp*Fe(1,2-Cy2PC6H4S) exclusively produces an iron ethenylidene, Cp*Fe(=C=CH2)(1,2-Cy2PC6H4S) (2). Protonation of the ethenylidene causes nucleophilic attack of the Cα by sulfur, affording a sulfur-tethered carbene complex, [Cp*Fe=C(CH3)SC6H4PCy2]+ (3+). This Fischer-type carbene complex undergoes an unusual isomerization by migrating a hydrogen atom from the ß-CH3 group to the α-C, leading to the formation of an olefin complex [Cp*Fe(η4-CH=CH2SC6H4PCy2]+ (4+). Compound 2 also displays diverse redox reactivities. It transforms to a neutral acetylide ferric complex (5) when reacting with free radical scavengers and to a cationic vinyl complex [Cp*Fe(η3-C(=CH2)SC6H4PCy2]+ (6+) upon 1e- oxidation. The interconversion between the vinyl and acetylide complexes can be realized through protonation/deprotonation reactions.

Molecular Characterization and Function of the Nogo-66 Receptor (NgR1) Gene in the Chinese Tree Shrew.

BACKGROUND: Nogo-66 receptor (NgR1) is a glycosylphosphatidylinositol-linked cell surface receptor with high affinity for Nogo-66. The binding of Nogo-66 to NgR1 plays a key role in inhibiting neurite growth, limiting synaptic plasticity and mediating Mammalian Reovirus (MRV) infection. The Chinese tree shrew (Tupaia belangeri chinensis) is, a new and valuable experimental animal that is widely used in biomedical research. Although susceptible to MRV, little is known about tree shrew NgR1 and its role in MRV infection. METHODS: In this study, we cloned NgR1 form the Chinese tree shrew by RACE technology and analyzed its characteristics, spatial structure and its tissue expression. We also examined the expression pattern of NgR1 in the response of tree shrew primary nerve cells (tNC) to MRV1/TS/2011 infection. RESULTS: Tree shrew NgR1 was found to have a closer relationship to human NgR1 (90.34%) than to mouse NgR1. Similar to the protein structure of human NgR1, the tree shrew NgR1 has the same leucine-rich repeat (LRR) domain structure that is capped by C-terminal and N-terminal cysteine-rich modules. The tree shrew NgR1 mRNAs were predominantly detected in the central nervous system (CNS), and tree shrew NgR1 can mediate infection by MRV1/TS/2011. CONCLUSIONS: Taken together, these results help to elucidate the function of NgR1 and provide a basis for using the tree shrew as an animal model for studies of the nervous system and infectious diseases.

A Parent Iron Amido Complex in Catalysis of Ammonia Oxidation.

Parent amido complexes are crucial intermediates in ammonia-based transformations. We report a well-defined ferric ammine system [Cp*Fe(1,2-Ph2PC6H4NH)(NH3)]+ ([1-NH3]+), which processes electrocatalytic ammonia oxidation to N2 and H2 at a mild potential. Through establishing elementary e-/H+ conversions with the ferric ammine, a formal Fe(IV)-amido species, [1-NH2]+, together with its conjugated Lewis acid, [1-NH3]2+, was isolated and structurally characterized for the first time. Mechanism studies indicated that further oxidation of [1-NH2]+ induces the reaction of the parent amido unit with NH3. The formation of hydrazine is realized by the non-innocent nature of the phenylamido ligand that facilitates the concerted transfer of one proton and two electrons.

Genomes shed light on the evolution of Begonia, a mega-diverse genus.

Clarifying the evolutionary processes underlying species diversification and adaptation is a key focus of evolutionary biology. Begonia (Begoniaceae) is one of the most species-rich angiosperm genera with c. 2000 species, most of which are shade-adapted. Here, we present chromosome-scale genome assemblies for four species of Begonia (B. loranthoides, B. masoniana, B. darthvaderiana and B. peltatifolia), and whole genome shotgun data for an additional 74 Begonia representatives to investigate lineage evolution and shade adaptation of the genus. The four genome assemblies range in size from 331.75 Mb (B. peltatifolia) to 799.83 Mb (B. masoniana), and harbor 22 059-23 444 protein-coding genes. Synteny analysis revealed a lineage-specific whole-genome duplication (WGD) that occurred just before the diversification of Begonia. Functional enrichment of gene families retained after WGD highlights the significance of modified carbohydrate metabolism and photosynthesis possibly linked to shade adaptation in the genus, which is further supported by expansions of gene families involved in light perception and harvesting. Phylogenomic reconstructions and genomics studies indicate that genomic introgression has also played a role in the evolution of Begonia. Overall, this study provides valuable genomic resources for Begonia and suggests potential drivers underlying the diversity and adaptive evolution of this mega-diverse clade.

Nanosized Carbon Macrocycles Based on a Planar Chiral Pseudo Meta-[2.2]Paracyclophane.

Structural designs combining cycloparaphenylenes (CPPs) backbone with planar chiral [2.2]paracyclophane ([2.2]PCP) lead to optical-active chiral macrocycles with intriguing properties. X-ray crystal analysis revealed aesthetic necklace-shaped structures and size-dependent packages with long-range channels. The macrocycles exhibit unique photophysical properties with high fluorescence quantum yield of up to 82 %, and the fluorescent color varies with ring size. In addition, size-dependent chiroptical properties with moderately large CPL dissymmetry factor of 10-3 and CPL brightness in the range of 30-40 M-1 cm-1 were observed.

Fluorinated Hyaluronic Acid Encapsulated Perfluorocarbon Nanoparticles as Tumor-Targeted Oxygen Carriers to Enhance Radiotherapy.

The efficacy of radiotherapy is significantly constricted by tumor hypoxia. To overcome this obstacle, one promising approach is to use the perfluorocarbon-based O2 carriers combined with hyperoxic respiration to relieve tumor hypoxia. However, this passively transported oxygen carrier during hyperoxic respiration is prone to cause systemic oxidative stress and toxicity, which further limits its clinical application. Herein, we fabricate O2@PFC@FHA NPs for safe and specific oxygen delivery into tumors by using the fluorinated hyaluronic acid to encapsulate O2-saturated perfluorocarbon. Due to the interaction between HA and CD44 receptors, more FHA@PFC NPs accumulated in the tumor and the O2@PFC@FHA NPs significantly relieved tumor hypoxia. Notably, RT plus O2@PFC@FHA NPs resulted in almost threefold therapeutic improvement compared with RT without obvious systemic toxicity. Therefore, the O2@FHA@PFC NPs may have great potential to enhance the therapeutic efficacy of radiotherapy in the clinic.

Bioinspired Iron-Catalyzed Dehydration of Aldoximes to Nitriles: A General N-O Redox-Cleavage Method.

Inspired by OxdA that operates biocatalytic aldoxime dehydration, we have developed an efficient iron catalyst, Cp*Fe(1,2-Cy2PC6H4O) (1), which rapidly converts various aliphatic and aromatic aldoximes to nitriles with release of H2O at room temperature. The catalysis involves redox activation of the N-O bond by a 1e- transfer from the iron catalyst to the oxime. Such redox-mediated N-O cleavage was demonstrated by the isolation of a ferrous iminato intermediate from the reaction of the ketoxime substrate. This iron-catalyzed acceptorless dehydration approach represents a general method for the preparation of nitriles, and it also delivers salicylonitriles by catalyzing the Kemp elimination reaction.

Facile Transformations of a Binuclear Cp*Co(II) Diamidonaphthalene Complex to Mixed-Valent Co(II)Co(III), Co(III)(µ-H)Co(III), and Co(III)(µ-OH)Co(III) Derivatives.

A diamido-bridged dicobalt complex supported by a diamidonaphthalene ligand, Cp*2Co2(µ-1,8-C10H8(NH)2) (1), was synthesized, and the reactivity relevant to redox transformations of the Co2N2 core was investigated. It was found that the Co(II)-Co(II) bond allows for protonation by [HPPh3][BF4] resulting in a bridging hydride, [1H]+, with pKa ∼ 7.6 in CH2Cl2. The diamidonaphthalene ligand can stabilize the binuclear system in the Co(II)Co(III) mixed-valent state (1+), which is capable of binding CO to afford [1-CO]+. Surprisingly, the mixed-valent complex also activates H2O to furnish a Co(III)Co(III) hydroxy complex [1-OH]+ accompanied by release of H2. The hydroxy ligand in [1-OH]+ is exchangeable, as demonstrated by 18O-labeling experiments on [1-OH]+ with H218O that led to the heavier isotopolog [1-18OH]+.

Identification of SEC14 like lipid binding 2(SEC14L2) sequence and expression profiles in the Chinese tree shrew (Tupaia belangeri chinensis).

BACKGROUND: The product of the SEC14L2 (SEC14 Like Lipid Binding 2) gene belongs to a family of lipid-binding proteins including Sec14p, alpha-tocopherol transfer protein, and cellular retinol-binding protein. SEC14L2 expression enables replication of clinical hepatitis C virus (HCV) isolates in several hepatoma cell lines, and mutations in SEC14L2 may enhance HCV replication in vitro. The Chinese tree shrew (Tupaia belangeri chinensis) is a potential animal model for studying HCV replication, however, the cDNA sequence, protein structure, and expression of the Chinese tree shrew SEC14L2 gene have yet to be characterized. METHODS AND RESULTS: In the present study, we cloned the full-length cDNA sequence of the SEC14L2 in the Chinese tree shrew by using rapid amplification of cDNA ends technology. This led us to determine that, this is 2539 base pairs (bp) in length, the open reading frame sequence is 1212 bp, and encodes 403 amino acids. Following this, we constructed a phylogenetic tree based on SEC14L2 molecules from various species and compared SEC14L2 amino acid sequence with other species. This analysis indicated that the Chinese tree shrew SEC14L2 protein (tsSEC14L2) has 96.28% amino acid similarity to the human protein, and is more closely related to the human protein than either mouse or rat protein. The Chinese tree shrew SEC14L2 mRNA was detected in all tissues, and showed highest expression levels in the pancreas, small intestine and trachea, however the tsSEC14L2 protein abundance was highest in the liver and small intestine. CONCLUSION: The Chinese tree shrew SEC14L2 gene was closer in evolutionary relation to humans and non-human primates and expression of the tsSEC14L2 protein was highest in the liver and small intestine. These results may provide useful information for tsSEC14L2 function in HCV infection.

First Report of Colletotrichum karstii Causing Anthracnose of Begonia lanternaria Irmsch. in China.

Begonia lanternaria Irmsch., an ornamental plant endemic in China, which is commonly used in landscape and interior decoration. In March 2021, an estimated 30% B. lanternaria plants were observed with anthracnose-like symptoms at a botanical garden conservation greenhouse in Mengla County of Yunnan Province (21.91° N, 101.21°E). Initially, small black spots developed on the disease leaves, which gradually expanded into irregular necrotic lesions surrounded by a yellowish halo, eventually turned wilting and defoliating. Twenty diseased leaves were collected and surface-disinfested with 75% ethanol for 30 s. Small fragments (5 × 5 mm) from the margin of lesions were disinfected with 1% NaClO for 120 s, washed with sterile water three times, and cultured on potato dextrose agar (PDA) at 28 ± 1℃. After 3 days single spores from four fungal colonies with identical morphology were isolated. Colonies on PDA were 70-75 mm diam in 7 d (7.5-10.6 mm/d), with dense white to gray-white mycelia attached with brown to black-brown acervulus. The underside of the culture was yellow to yellowish-brown concentric circle. Conidia were single-celled, hyaline, straight to slightly curved, cylindrical, 12.88 to 16.66 × 6.25 to 7.97 µm (av=14.65 µm × 7.22 µm, n=50) in size. For molecular identification, genomic DNA was extracted from a representative isolate, and the internal transcribed spacer, glyceraldehyde-3-phosphate dehydrogenase, calmodulin gene, ß-tublin, actin, and chitin synthase 1 genes were amplified with ITS1/ITS4 (Gardes et al, 1993), GDF/GDR (Templeton et al, 1992), CL1C/CL2C (Li et al, 2018), Bt2a/Bt2b (Prihastuti et al, 2009), ACT-512F/ACT-783R and CHS-79F/CHS-345R (Carbone et al, 1999) primers, respectively. The obtained DNA sequences showed over 99% homology with Colletotrichum karsti (GenBank Accession No. ITS: NR144790; GAPDH: KX578772; CAL: KY039988; TUB2: KX578804; ACT: LC412408; CHS1: KU251855), and the results of sequences were deposited into GenBank with accession No. MZ496954 (522/522 bp), MZ504978 (238/238 bp), MZ504979 (737/737 bp), MZ504982 (472/472 bp), MZ504981 (273/273 bp), MZ504980 (282/284 bp). The phylogenetic tree combined with ITS-ACT-GAPDH-CHS 1-CAL-TUB2 concatenated sequences using the maximum likelihood methods showed that the isolate was C. karsti. To confirm pathogenicity, Koch's postulates were conducted on intact plants, 10 µl spore suspension (1.0 × 106 conidia/ml) of each of four isolates (7-day-old culture on PDA) was inoculated on 15 wounded with a sterilized needle or non-wounded healthy living leaves, and 15 wounded leaves were inoculated with sterile water as controls. All leaves were incubated at 28 ± 1°C and 90% relative humidity (12 h/12 h light/dark). After 5 days, all wounded leaves inoculated with C. karsti showed symptoms similar to those previously observed, while the control and non-wounded leaves remained healthy. Colletotrichum karsti was re-isolated from inoculated leaves. C. karsti was previously reported to cause disease on Nicotiana tabacum L. (Zhao et al, 2020), Stylosanthes guianensis (Jia et al, 2017) and Fatsia japonica (Xu et al, 2020) in China. To our knowledge, this is the first report of C. karsti causing anthracnose of B. lanternaria Irmsch. in China. This disease reduces the ornamental and economic value of B. lanternaria Irmsch., and this work will provide a basis for the prevention and treatment of the disease in the future.

Iron-Catalyzed Regiodivergent Hydrostannation of Alkynes: Intermediacy of Fe(IV)-H versus Fe(II)-Vinylidene.

We report an iron system, Cp*Fe(1,2-R2PC6H4X), which controls the Markovnikov and anti-Markovnikov hydrostannation of alkynes by tuning the ionic metal-heteroatom bonds (Fe-X) reactivity. The sequential addition of nBu3SnH to the iron-amido catalyst (1, X = HN-, R = Ph) affords a distannyl Fe(IV)-H species responsible for syn-addition of the Sn-H bond across the C≡C bond to produce branched α-vinylstannanes. Activation of the C(sp)-H bond of alkynes by an iron-aryloxide catalyst (2, X = O-, R = Cy) affords an iron(II) vinylidene intermediate, allowing for gem-addition of the Sn-H to the terminal-carbon producing ß-vinylstannanes. These catalytic reactions exhibit excellent regioselectivity and broad functional group compatibility and enable the large-scale synthesis of diverse vinylstannanes. Many new reactions have been established based on such a synthetic Fe-X platform to demonstrate that the initial step of the catalysis is conveniently controlled by the activation of either the tin hydride or the alkyne substrate.

LAZY2 controls rice tiller angle through regulating starch biosynthesis in gravity-sensing cells.

Rice (Oryza sativa) tiller angle is a key component for achieving ideal plant architecture and higher grain yield. However, the molecular mechanism underlying rice tiller angle remains elusive. We characterized a novel rice tiller angle mutant lazy2 (la2) and isolated the causative gene LA2 through map-based cloning. Biochemical, molecular and genetic studies were conducted to elucidate the LA2-involved tiller angle regulatory mechanism. The la2 mutant shows large tiller angle with impaired shoot gravitropism and defective asymmetric distribution of auxin. We found that starch granules in amyloplasts are completely lost in the gravity-sensing leaf sheath base cells of la2, whereas the seed development is not affected. LA2 encodes a novel chloroplastic protein that can interact with the starch biosynthetic enzyme Oryza sativa plastidic phosphoglucomutase (OspPGM) to regulate starch biosynthesis in rice shoot gravity-sensing cells. Genetic analysis showed that LA2 regulates shoot gravitropism and tiller angle by acting upstream of LA1 to mediate lateral auxin transport. Our studies revealed that LA2 acts as a novel regulator of rice tiller angle by specifically regulating starch biosynthesis in gravity-sensing cells, and established the framework of the starch-statolith-dependent rice tiller angle regulatory pathway, providing new insights into the rice tiller angle regulatory network.

Molecular cloning and characterization of NPC1L1 in the Chinese tree shrew (Tupaia belangeri chinensis).

BACKGROUND: The Niemann-Pick C1-Like 1 protein, a multi-transmembrane domain molecule, is critical for intestinal cholesterol absorption, and is the entry factor for hepatitis C virus (HCV). The Chinese tree shrew (Tupaia belangeri chinensis) is closer to primates in terms of genetic evolution than rodents. Previous studies indicated that the tree shrew was suitable for HCV research; however, little is known about tree shrew NPC1L1. METHODS AND RESULTS: TsNPC1L1 cDNA was amplified by rapid amplification of cDNA ends (RACE) technology. The cDNA sequence, its encoded protein structure, and expression profile were analyzed. Results indicated that the tsNPC1L1 mRNA is 4948 bp in length and encodes a 1326 amino acid protein. TsNPC1L1 possesses 84.97% identity in homology to human NPC1L1 which is higher than both mouse (80.37%) and rat (81.80%). The protein structure was also similar to human with 13 conserved transmembrane helices, and a sterol-sensing domain (SSD). Like human NPC1L1, the tsNPC1L1 mRNA transcript is highly expressed in small intestine, but it was also well-expressed in the lung and pancreas of the tree shrew. CONCLUSION: The homology of tree shrew NPC1L1 was closer to human than that of rodent NPC1L1. The expression of tsNPC1L1 was the highest in small intestine, and was detectable in lung and pancreas. These results may be useful in the study of tsNPC1L1 function in cholesterol absorption and HCV infection.

Response of the gut microbiota during the Clostridioides difficile infection in tree shrews mimics those in humans.

BACKGROUND: Clostridioides difficile is a major cause of antibiotic associated diarrhea. Several animal models are used to study C. difficile infection (CDI). The tree shrew has recently been developed as a model of primate processes. C. difficile infection has not been examined in tree shrews. We infected tree shrews with hyper-virulent C. difficile strains and examined the alterations in gut microbiota using 16S rRNA gene sequencing. RESULTS: C. difficile colonized the gastrointestinal tract of tree shrew and caused diarrhea and weight loss. Histopathologic examination indicated structures and mucosal cell destruction in ileal and colonic tissues. The gut microbial community was highly diversity before infection and was dominated by Firmicutes, Fusobacteria, Bacteroidetes, and Proteobacteria. Antibiotic administration decreased the diversity of the gut microbiota and led to an outgrowth of Lactobacillus. The relative abundance of Proteobacteria, Gammaproteobacteria, Enterobacteriales, Lachnospiraceae, Enterobacteriaceae, Escherichia, Blautia, and Tyzzerella increased following C. difficile infection. These taxa could be biomarkers for C. difficile colonization. CONCLUSIONS: In general, the disease symptoms, histopathology, and gut microbiota changes following C. difficile infection in tree shrews were similar to those observed in humans.