Trx4, a novel thioredoxin protein, is important for Toxoplasma gondii fitness

BACKGROUND

To successfully replicate within the host cell, Toxoplasma gondii employs several mechanisms to overcome the host cell defenses and mitigate the harmful effects of the free radicals resulting from its own metabolic processes using effectors such as thioredoxin proteins. In this study, we characterize the location and functions of a newly identified thioredoxin in T. gondii, which was named Trx4.

METHODS

We characterized the functional role of Trx4 in T. gondii Type I RH and Type II Pru strains by gene knockout and studied its subcellular localization by endogenous protein HA tagging using CRISPR-Cas9 gene editing. The enzyme-catalyzed proximity labeling technique, the TurboID system, was employed to identify the proteins in proximity to Trx4.

RESULTS

Trx4 was identified as a dense granule protein of T. gondii predominantly expressed in the parasitophorous vacuole (PV) and was partially co-localized with GRA1 and GRA5. Functional analysis showed that deletion of trx4 markedly influenced the parasite lytic cycle, resulting in impaired host cell invasion capacity in both RH and Pru strains. Mutation of Trx domains in Trx4 in RH strain revealed that two Trx domains were important for the parasite invasion. By utilizing the TurboID system to biotinylate proteins in proximity to Trx4, we identified a substantial number of proteins, some of which are novel, and others are previously characterized, predominantly distributed in the dense granules. In addition, we uncovered three novel proteins co-localized with Trx4. Intriguingly, deletion of trx4 did not affect the localization of these three proteins. Finally, a virulence assay demonstrated that knockout of trx4 resulted in a significant attenuation of virulence and a significant reduction in brain cyst loads in mice.

CONCLUSIONS

Trx4 plays an important role in T. gondii invasion and virulence in Type I RH strain and Type II Pru strain. Combining the TurboID system with CRISPR-Cas9 technique revealed many PV-localized proximity proteins associated with Trx4. These findings suggest a versatile role of Trx4 in mediating the processes that occur in this distinctive intracellular membrane-bound vacuolar compartment.

A newly characterized dense granule protein (GRA76) is important for the growth and virulence of Toxoplasma gondii

Pathogenicity of the zoonotic pathogen Toxoplasma gondii largely depends on the secretion of effector proteins into the extracellular milieu and host cell cytosol, including the dense granule proteins (GRAs). The protein-encoding gene TGME49_299780 was previously identified as a contributor to parasite fitness. However, its involvement in parasite growth, virulence and infectivity in vitro and in vivo remains unknown. Here, we comprehensively examined the role of this new protein, termed GRA76, in parasite pathogenicity. Subcellular localization revealed high expression of GRA76 in tachyzoites inside the parasitophorous vacuole (PV). However, its expression was significantly decreased in bradyzoites. A CRISPR-Cas9 approach was used to knock out the gra76 gene in the T. gondii type I RH strain and type II Pru strain. The in vitro plaque assays and intracellular replication showed the involvement of GRA76 in replication of RH and Pru strains. Deletion of the gra76 gene significantly decreased parasite virulence, and reduced the brain cyst burden in mice. Using RNA sequencing, we detected a significant increase in the expression of bradyzoite-associated genes such as BAG1 and LDH2 in the PruΔgra76 strain compared with the wild-type Pru strain. Using an in vitro bradyzoite differentiation assay, we showed that loss of GRA76 significantly increased the propensity for parasites to form bradyzoites. Immunization with PruΔgra76 conferred partial protection against acute and chronic infection in mice. These findings show the important role of GRA76 in the pathogenesis of T. gondii and highlight the potential of PruΔgra76 as a candidate for a live-attenuated vaccine.

The transcription factor AP2XI-2 is a key negative regulator of Toxoplasma gondii merogony

Sexual development in Toxoplasma gondii is a multistep process that culminates in the production of oocysts, constituting approximately 50% of human infections. However, the molecular mechanisms governing sexual commitment in this parasite remain poorly understood. Here, we demonstrate that the transcription factors AP2XI-2 and AP2XII-1 act as negative regulators, suppressing merozoite-primed pre-sexual commitment during asexual development. Depletion of AP2XI-2 in type II Pru strain induces merogony and production of mature merozoites in an alkaline medium but not in a neutral medium. In contrast, AP2XII-1-depleted Pru strain undergoes several rounds of merogony and produces merozoites in a neutral medium, with more pronounced effects observed under alkaline conditions. Additionally, we identified two additional AP2XI-2-interacting proteins involved in repressing merozoite programming. These findings underscore the intricate regulation of pre-sexual commitment by a network of factors and suggest that AP2XI-2 or AP2XII-1-depleted Pru parasites can serve as a model for studying merogony in vitro.

The Toxoplasma protein phosphatase 6 catalytic subunit (TgPP6C) is essential for cell cycle progression and virulence

Protein phosphatases are post-translational regulators of Toxoplasma gondii proliferation, tachyzoite-bradyzoite differentiation and pathogenesis. Here, we identify the putative protein phosphatase 6 (TgPP6) subunits of T. gondii and elucidate their role in the parasite lytic cycle. The putative catalytic subunit TgPP6C and regulatory subunit TgPP6R likely form a complex whereas the predicted structural subunit TgPP6S, with low homology to the human PP6 structural subunit, does not coassemble with TgPP6C and TgPP6R. Functional studies showed that TgPP6C and TgPP6R are essential for parasite growth and replication. The ablation of TgPP6C significantly reduced the synchronous division of the parasite's daughter cells during endodyogeny, resulting in disordered rosettes. Moreover, the six conserved motifs of TgPP6C were required for efficient endodyogeny. Phosphoproteomic analysis revealed that ablation of TgPP6C predominately altered the phosphorylation status of proteins involved in the regulation of the parasite cell cycle. Deletion of TgPP6C significantly attenuated the parasite virulence in mice. Immunization of mice with TgPP6C-deficient type I RH strain induced protective immunity against challenge with a lethal dose of RH or PYS tachyzoites and Pru cysts. Taken together, the results show that TgPP6C contributes to the cell division, replication and pathogenicity in T. gondii.

[Clinical characteristics of a case of severe pneumonia caused by coinfection of COVID-19 and Chlamydia Psittaci]

A 69-year-old female patient was admitted to the Department of Respiratory and Critical Care Medicine, Affiliated Hospital of Xuzhou Medical University due to a "cough and fever for eight days". On admission, a coronavirus disease (COVID-19) nucleic acid test was positive, and a chest CT scan showed progressive patchy shadows and consolidation shadows in both lungs. Arterial blood gas analysis showed type Ⅰ respiratory failure. The primary diagnosis was severe community-acquired pneumonia in an older adult without underlying disease. However, oxygen inhalation, steroid, anti-inflammatory, and antibacterial empirical treatment with piperacillin/tazobactam was ineffective. Metagenomic next-generation sequencing of bronchoscopy alveolar lavage fluid showed Chlamydia psittaci(C. psittaci). Severe pneumonia was confirmed, caused by coinfection with severe acute respiratory syndrome coronavirus 2 and C. psittaci. A combination of doxycycline and moxifloxacin significantly improved the targeted and symptomatic treatment of the underlying cause. After discharge, the patient recovered within four weeks of follow-up. Therefore, clinicians should be alert to the possibility of coinfection of C. psittaci in patients already diagnosed with COVID-19.

The antioxidant protein glutaredoxin 1 is essential for oxidative stress response and pathogenicity of Toxoplasma gondii

Glutaredoxins (Grxs) are ubiquitous antioxidant proteins involved in many molecular processes to protect cells against oxidative damage. Here, we study the roles of Grxs in the pathogenicity of Toxoplasma gondii. We show that Grxs are localized in the mitochondria (Grx1), cytoplasm (Grx2), and apicoplast (Grx3, Grx4), while Grx5 had an undetectable level of expression. We generated Δgrx1-5 mutants of T. gondii type I RH and type II Pru strains using CRISPR-Cas9 system. No significant differences in the infectivity were detected between four Δgrx (grx2-grx5) strains and their respective wild-type (WT) strains in vitro or in vivo. Additionally, no differences were detected in the production of reactive oxygen species, total antioxidant capacity, superoxide dismutase activity, and sensitivity to external oxidative stimuli. Interestingly, RHΔgrx1 or PruΔgrx1 exhibited significant differences in all the investigated aspects compared to the other grx2-grx5 mutant and WT strains. Transcriptome analysis suggests that deletion of grx1 altered the expression of genes involved in transport and metabolic pathways, signal transduction, translation, and obsolete oxidation-reduction process. The data support the conclusion that grx1 supports T. gondii resistance to oxidative killing and is essential for the parasite growth in cultured cells and pathogenicity in mice and that the active site CGFS motif was necessary for Grx1 activity.

Seroprevalence and risk factors of Toxoplasma gondii and Neospora caninum infection in black goats in Yunnan Province, Southwestern China

Toxoplasma gondii and Neospora caninum are two obligate intracellular protozoan parasites that can cause reproductive failure and production losses. To date, there is no data of T. gondii and N. caninum seroprevalence in black goats in Yunnan Province, southwestern China. In the present study, a total of 734 serum samples were collected from black goats in four different counties of Yunnan Province. 734 and 590 serum samples were examined for antibodies against T. gondii and N. caninum by using MAT and indirect ELISA, respectively. A total of 123 and 76 samples were T. gondii-positive and N. caninum-positive, respectively. The overall seroprevalence of T. gondii in black goats was 16.76% (123/734, 95% CI: 14.06-19.46) with the titer ranged from 1:25 to 1:3200. The seroprevalence of N. caninum was 12.88% (76/590, 95% CI: 10.18-15.58). There was significant difference in seroprevalence of N. caninum in different regions (P < 0.01, χ² = 30.63) and age groups (P < 0.05, χ² = 11.85). Significant differences in seroprevalence of T. gondii were observed in different regions (P < 0.05, χ² = 9.21) and different gender groups (P < 0.01, χ² = 12.29). Results of seroprevalence of T. gondii and N. caninum indicated that T. gondii and N. caninum were prevalent parasites in black goats in Yunnan Province. This is the first report of seroprevalence of T. gondii and N. caninum in black goats in Yunnan Province. The results of this study indicated that some measures should be taken to control these two parasites and to reduce economic losses to the livestock industry in Yunnan Province.

[Joinpoint regression analysis of the incidence trend of syphilis and gonorrhea among adolescents aged 10-19 in Liaoning Province from 2006 to 2020]

Joinpoint regression was used to analyze the trend of syphilis and gonorrhea incidence rate among 10-19 year old adolescents in Liaoning Province from 2006 to 2020. The syphilis and gonorrhea data in Liaoning Province were reported in the infectious disease monitoring system of China's disease prevention and control information system. From 2006 to 2020, a total of 7 721 cases of syphilis in 10-19 year old adolescents were reported in Liaoning Province, with an incidence rate about 0.90/100 000-22.13/100 000. The incidence rate of syphilis in women was higher than that in men. Adolescents infected with stage Ⅰ and stageⅡ syphilis accounted for 72.6%. There were 2 726 patients with gonorrhea, with an incidence rate about 1.29/100 000-10.74/100 000. The incidence rate of gonorrhea in men was higher than that in women. Joinpoint regression model analysis showed that the incidence of syphilis generally took 2012 as the inflection point. From 2006 to 2012, the average annual growth rate of syphilis incidence rate among adolescents was 67.30% (P<0.001). The average annual growth rate of syphilis incidence rate in adolescents from 2012 to 2020 was -0.02% (P=0.994).The overall incidence of gonorrhea incidence rate took 2015 as the inflection point. From 2006 to 2015, the average annual growth rate of juvenile gonorrhea incidence rate was 23.95% (P<0.001). The average annual growth rate of gonorrhea incidence rate in adolescents from 2015 to 2020 was 4.06% (P=0.492). Overall, from 2006 to 2020, the incidence rate of syphilis and gonorrhea among 10-19 year old adolescents in Liaoning Province increased slowly. The primary and secondary prevention strategies were significantly effective in reducing the risk of sexually transmitted diseases.

[Investigation on the growth factor regulatory network of dermal fibroblasts in mouse full-thickness skin defect wounds based on single-cell RNA sequencing]

Objective: To explore the heterogeneity and growth factor regulatory network of dermal fibroblasts (dFbs) in mouse full-thickness skin defect wounds based on single-cell RNA sequencing. Methods: The experimental research methods were adopted. The normal skin tissue from 5 healthy 8-week-old male C57BL/6 mice (the same mouse age, sex, and strain below) was harvested, and the wound tissue of another 5 mice with full-thickness skin defect on the back was harvested on post injury day (PID) 7. The cell suspension was obtained by digesting the tissue with collagenase D and DNase Ⅰ, sequencing library was constructed using 10x Genomics platform, and single-cell RNA sequencing was performed by Illumina Novaseq6000 sequencer. The gene expression matrices of cells in the two kinds of tissue were obtained by analysis of Seurat 3.0 program of software R4.1.1, and two-dimensional tSNE plots classified by cell group, cell source, and gene labeling of major cells in skin were used for visual display. According to the existing literature and the CellMarker database searching, the expression of marker genes in the gene expression matrices of cells in the two kinds of tissue was analyzed, and each cell group was numbered and defined. The gene expression matrices and cell clustering information were introduced into CellChat 1.1.3 program of software R4.1.1 to analyze the intercellular communication in the two kinds of tissue and the intercellular communication involving vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and fibroblast growth factor (FGF) signal pathways in the wound tissue, the relative contribution of each pair of FGF subtypes and FGF receptor (FGFR) subtypes (hereinafter referred to as FGF ligand receptor pairs) to FGF signal network in the two kinds of tissue, and the intercellular communication in the signal pathway of FGF ligand receptor pairs with the top 2 relative contributions in the two kinds of tissue. The normal skin tissue from one healthy mouse was harvested, and the wound tissue of one mouse with full-thickness skin defect on the back was harvested on PID 7. The multiple immunofluorescence staining was performed to detect the expression and distribution of FGF7 protein and its co-localized expression with dipeptidyl peptidase 4 (DPP4), stem cell antigen 1 (SCA1), smooth muscle actin (SMA), and PDGF receptor α (PDGFRα) protein. Results: Both the normal skin tissue of healthy mice and the wound tissue of full-thickness skin defected mice on PID 7 contained 25 cell groups, but the numbers of cells in each cell group between the two kinds of tissue were different. Genes PDGFRα, platelet endothelial cell adhesion molecule 1, lymphatic endothelial hyaluronic acid receptor 1, receptor protein tyrosine phosphatase C, keratin 10, and keratin 79 all had distinct distributions on two-dimensional tSNE plots, indicating specific cell groups respectively. The 25 cell groups were numbered by C0-C24 and divided into 9 dFb subgroups and 16 non-dFb groups. dFb subgroups included C0 as interstitial progenitor cells, C5 as adipose precursor cells, and C13 as contractile muscle cells related fibroblasts, etc. Non-dFb group included C3 as neutrophils, C8 as T cells, and C18 as erythrocytes, etc. Compared with that of the normal skin tissue of healthy mice, the intercellular communication in the wound tissue of full-thickness skin defected mice on PID 7 was more and denser, and the top 3 cell groups in intercellular communication intensity were dFb subgroups C0, C1, and C2, of which all communicated with other cell groups in the wound tissue. In the wound tissue of full-thickness skin defected mice on PID 7, VEGF signals were mainly sent by the dFb subgroup C0 and received by vascular related cell groups C19 and C21, PDGF signals were mainly sent by peripheral cells C14 and received by multiple dFb subgroups, EGF signals were mainly sent by keratinocyte subgroups C9 and C11 and received by the dFb subgroup C0, and the main sender and receiver of FGF signals were the dFb subgroup C6. In the relative contribution rank of FGF ligand receptor pairs to FGF signal network in the normal skin tissue of healthy mice and the wound tissue of full-thickness skin defected mice on PID 7, FGF7-FGFR1 was the top 1, and FGF7-FGFR2 or FGF10-FGFR1 was in the second place, respectively; compared with those in the normal skin tissue, there was more intercellular communication in FGF7-FGFR1 signal pathway, while the intercellular communication in FGF7-FGFR2 and FGF10-FGFR1 signal pathways decreased slightly or did not change significantly in the wound tissue; the intercellular communication in FGF7-FGFR1 signal pathway in the wound tissue was stronger than that in FGF7-FGFR2 or FGF10-FGFR1 signal pathway; in the two kinds of tissue, FGF7 signal was mainly sent by dFb subgroups C0, C1, and C2, and received by dFb subgroups C6 and C7. Compared with that in the normal skin tissue of healthy mouse, the expression of FGF7 protein was higher in the wound tissue of full-thickness skin defected mouse on PID 7; in the normal skin tissue, FGF7 protein was mainly expressed in the skin interstitium and also expressed in the white adipose tissue near the dermis layer; in the two kinds of tissue, FGF7 protein was co-localized with DPP4 and SCA1 proteins and expressed in the skin interstitium, co-localized with PDGFRα protein and expressed in dFbs, but was not co-localized with SMA protein, with more co-localized expression of FGF7 in the wound tissue than that in the normal skin tissue. Conclusions: In the process of wound healing of mouse full-thickness skin defect wound, dFbs are highly heterogeneous, act as potential major secretory or receiving cell populations of a variety of growth factors, and have a close and complex relationship with the growth factor signal pathways. FGF7-FGFR1 signal pathway is the main FGF signal pathway in the process of wound healing, which targets and regulates multiple dFb subgroups.

Functional Characterization of 17 Protein Serine/Threonine Phosphatases in Toxoplasma gondii Using CRISPR-Cas9 System

Protein serine/threonine phosphatases (PSPs), found in various plants and protozoa, are involved in the regulation of various biological processes. However, very little is known about the role of PSPs in the pathogenicity of the apicomplexan protozoan Toxoplasma gondii. Herein, the subcellular localization of 17 PSPs (PP5, PP7, EFPP, SLP, PPM3F, PPM4, PPM5A, PPM5B, PPM6, PPM8, PPM9, PPM12, PPM14, PPM18, CTD1, CTD2, and CTD3) was examined by 6× HA tagging of endogenous genes in C-terminal. The PSPs were detected in the cytoplasm (PP5, EFPP, PPM8, and CTD2), dense granules (SLP), nucleus (PPM4 and PPM9), inner membrane complex (PPM12), basal complex (CTD3), and apical pole (PP7). The remaining PSPs exhibited low or undetectable level of expression. To characterize the contribution of these genes to the infectivity of T. gondii, knock-out (KO) strains of type I RH strain deficient in the 17 psp genes and KO type II Pru strain deficient in pp7 and slp genes were constructed. The pathogenicity of individual RHΔpsp mutants was characterized in vitro using plaque, egress, and intracellular replication assays, and mouse infection, while pathogenicity of PruΔpp7 and PruΔslp mutant strains was evaluated by examining the parasite lytic cycle in vitro and assessment of brain cyst burden in mice. No significant differences were observed between 16 RHΔpsp strains and wild-type (WT) RH strain. However, RHΔpp7 exhibited significantly lower invasion efficiency and parasitophorous vacuole formation in vitro, and less virulence in mice compared with other RHΔpsp and WT strains. In addition, PruΔpp7 exhibited marked attenuation of virulence and significant reduction in the brain cyst burden in mice compared with PruΔslp and WT strains, suggesting the key role of PP7 in the virulence of T. gondii. Comparative transcriptomic profiling of the 17 psp genes showed that they may play different roles in the pathogenesis of different genotypes or life cycle stages of T. gondii. These findings provide new insight into the role of PSPs in the pathogenesis of T. gondii.

[Comparison of hereditary breast and ovarian cancer syndrome and sporadic ovarian cancer in ovarian cancer BRCA mutations]

Objective: To study the difference between BRCA gene mutations in hereditary breast and ovarian cancer syndrome (HBOC) and in sporadic ovarian cancer (SOC). Methods: This study was for exploratory research, the inclusion criteria were 284 patients with ovarian cancer admitted at Shanxi Provincial Cancer Hospital from November 2018 to December 2019, with high-throughput DNA sequencing including the full coding regions and exon-intron link regions of BRCA1 and BRCA2 gene. Pathogenic mutations in the BRCA gene of patients with ovarian cancer were collected and mutation site analysis was performed to compare phenotypic differences in pathogenic mutations between HBOC syndrome and SOC patients. Results: (1) Of the 284 ovarian cancer patients, seventy-seven had BRCA pathogenic mutations with a mutation rate of 27.1% (77/284), with BRCA1 mutation rate of 19.7% (56/284), BRCA2 gene 6.7% (19/284) and BRCA1/2 common mutation rate of 0.7% (2/284). Of the 284 patients with ovarian cancer, the pathogenic mutation rate in the BRCA gene in HBOC syndrome patients was 43.8% (32/73), which were significantly higher than that in SOC patients [21.3% (45/211); χ²=13.905, P<0.01]. Among BRCA1 gene mutation, the mutation rate in HBOC syndrome was higher than that of SOC [87.5% (28/32) vs 62.2% (28/45)], the BRCA2 gene mutation rate in patients with HBOC syndrome was lower than that in SOC patients [6.2% (2/32) vs 37.8% (17/45)], and there were statistically significant differences (all P<0.05). Two of the 77 patients with pathogenic mutations in the BRCA gene were multisite mutations, including one simultaneous two site mutation, one simultaneous three site mutation. There were 80 mutation sites with frameshift deletion mutations (55.0%, 44/80) and nonsense mutations (31.2%, 25/80). (2) Of the 73 patients with HBOC syndrome, 32 cases had pathogenic mutations in BRCA gene, including 28 cases in BRCA1, mainly in exon 11 and 24 (9 and 7 cases, respectively), and only two cases in BRCA2, both in exon 11; another two had multiple locus mutations. Of the 211 patients with SOC, 45 cases had pathogenic mutants in BRCA gene, including 28 cases in BRCA1, mainly in exon 11 and 24 (15 and 2 cases, respectively), and 17 cases in BRCA2, mainly in exon 11 (11 cases). (3) Thirty-four pathogenic mutation sites in BRCA gene were found newly, twenty of them were located in the BRCA1 gene, including a locus located on the intron 6, 301+1G>A, and the remaining 19 sites were located on the exons, including 283_286delCTTG, 68_69delAG, 132C>T, 514_547+3del37, 742delA, 1126_1129delAATA, 1196delA, 1352_1364del, 1465G>T, 2171delC, 2341G>T, 3359_3363delTTAAT, 4085_4086ins11, 4161_4162delTC, 4165_4166delAG, 4258G>T, 4338_4339del8insAGAA, 4468G>T, and 4783delA; fourteen sites were located in the BRCA2 gene, including a locus located on the intron 7, 631+1G>A, and the remaining 13 sites were located on the exons, including 2648delT, 2914A>T, 2950_2951insG, 4357+1G>A, 5054C>T, 5257A>T, 5291_5292insTC, 5913delT, 3593delA, 6091_6092insA, 6135_6136delTT, 7452delT, 9097_9098insA. A tal of 28 repeat mutations were located in the BRCA1 gene; among them, the site 5470_5477del8 was repeated 6 times, while 3 times in 981_982delAT. Conclusions: Patients with HBOC syndrome have a significantly higher rate of pathogenic mutation in the BRCA gene than that in patients with SOC. BRCA gene pathogenic mutation sites in HBOC syndrome patients occur commonly in exon 11 and 24 of BRCA 1 gene, while SOC patients occur mainly in exon 11 and 24 of BRCA1 gene and exon 11 of BRCA2 gene. The two loci of BRCA1∶5470_5477del8, BRCA1∶981_982delAT may be ancestor mutations in Chinese ovarian cancer patients, and 34 newly discovered pathogenic mutations in the BRCA gene, enriching the BRCA gene mutation spectrum in the Chinese population.

The Role of Type II Fatty Acid Synthesis Enzymes FabZ, ODSCI, and ODSCII in the Pathogenesis of Toxoplasma gondii Infection

Toxoplasma gondii is an obligate intracellular protozoan parasite, which has a worldwide distribution and can infect a large number of warm-blooded animals and humans. T. gondii must colonize and proliferate inside the host cells in order to maintain its own survival by securing essential nutrients for the development of the newly generated tachyzoites. The type II fatty acid biosynthesis pathway (FASII) in the apicoplast is essential for the growth and survival of T. gondii. We investigated whether deletion of genes in the FASII pathway influences the in vitro growth and in vivo virulence of T. gondii. We focused on beta-hydroxyacyl-acyl carrier protein dehydratase (FabZ) and oxidoreductase, short chain dehydrogenase/reductase family proteins ODSCI and ODSCII. We constructed T. gondii strains deficient in FabZ, ODSCI, and ODSCII using CRISPR-Cas9 gene editing technology. The results of immunofluorescence assay, plaque assay, proliferation assay and egress assay showed that in RHΔFabZ strain the apicoplast was partly lost and the growth ability of the parasite in vitro was significantly inhibited, while for RHΔODSCI and RHΔODSCII mutant strains no similar changes were detected. RHΔFabZ exhibited reduced virulence for mice compared with RHΔODSCI and RHΔODSCII, as shown by the improved survival rate. Deletion of FabZ in the PRU strain significantly decreased the brain cyst burden in mice compared with PRUΔODSCI and PRUΔODSCII. Collectively, these findings suggest that FabZ contributes to the growth and virulence of T. gondii, while ODSCI and ODSCII do not contribute to these traits.

Crown ether-based anion exchange membranes with highly efficient dual ion conducting pathways

Anion exchange membranes (AEMs) are a crucial constituent for alkaline fuel cells. As the core component of fuel cells, the low performance AEMs restrict the development and application of the fuel cells. Herein, the trade-off between the OH^- conductivity and dimensional stability was solved by constructing AEMs with adequate OH^- conductivity and satisfactory alkali resistance using Tröger's base (TB) poly (crown ether)s (PCEs) as the main chain, the embedded quaternary ammonium (QA) and Na⁺-functionalized crown ether units as the cationic group. Crown ether is an electron donator, and can capture Na⁺ to form Na⁺-functionalized crown ether units to conveniently transfer OH^- and significantly promote the alkaline stability of the AEMs. The influence of the Na⁺-functionalized crown ether units on the performance of AEMs was studied in detail. The PCEs based AEMs show an obvious hydrophobic-hydrophilic microphase separation. These features make them ideal platforms for the OH^- conduction applications. As expected, the as-prepared PCEs-QA-100% (100% is the degree of cross-linking) AEM with an ionic exchange capacity (IEC) of 2.07 meq g^-1 has a high OH^- conductivity of 159 mS cm^-1 at 80 °C. Furthermore, the membrane electrode assemblies fabricated using the PCEs-QA-100% AEM possess a maximum power density of 291 mW cm^-2 under the current density of 500 mA cm^-2.

Leptin reduces ventilator-induced lung injury in rats by regulating NLRP3, NLRC4 and NLRC3

Leptin has been linked to acute lung injury (ALI) through its regulation of immune responses. We aimed to scrutinize the effects of leptin on nucleotide oligomerization domain-like receptors containing pyrin domain 3 (NLRP3), nucleotide oligomerization domain-like receptors with caspase activation and recruitment domain 4 (NLRC4), and nucleotide oligomerization domain-like receptors with caspase activation and recruitment domain 3 (NLRC3), as an essential part of the immune system, in ventilator-induced lung injury (VILI) of rats. In the present study, pathogen-free adult male SD rats were given saline or leptin, followed by ventilation. Lung tissue samples, bronchoalveolar lavage fluids (BALF), and blood were collected four hours after installation. Notable acute lung inflammation induced by mechanical ventilation is well-characterized by a massive increase in lung injury score and wet/dry weight (W/D) ratio. We also observed VILI was associated with interleukin (IL-1β and IL-18). Rats that received ventilation showed a decrease in the levels of NLRP3 and NLRC4, and an increased level of NLRC3. Pre-treatment with leptin could abolish all of these effects induced by VILI. It has been suggested that the regulation of NLRP3, NLRC4, and NLRC3 may underlie the protection observed during VILI by exogenous leptin.

Functional Characterization of Two Thioredoxin Proteins of Toxoplasma gondii Using the CRISPR-Cas9 System

Toxoplasmosis caused by infection with Toxoplasma gondii is an important parasitic zoonosis with a worldwide distribution. In this study, we examined the functions of two thioredoxins (namely CTrp26 and CTrx1) of T. gondii tachyzoites by generation of HA tag strains or gene deficient parasites in Type I RH strain (ToxoDB#10). Immunofluorescence analysis (IFA) was used to investigate the subcellular localization of the thioredoxins (Trxs). Results of IFA showed that both CTrp26 and CTrx1 were located in the cytoplasm of T. gondii. Functional characterizations of CTrp26 and CTrx1-deficient parasites were performed by plaque assay, intracellular replication, egress, H₂O₂ resistance, detection of reactive oxygen species (ROS) level and total antioxidant capacity (T-AOC) assays in vitro, as well as mouse infection in vivo. Our results showed that deletion of CTrp26 or CTrx1 did not influence the ability of T. gondii RH strain to replicate, egress, form plaque, resist H₂O₂ exposure, maintain the ROS level, and T-AOC, and also did not serve as virulence factors in Kunming mice. Taken together, these results provide new properties of the two Trxs. Although they are not essential for RH strain, they may have roles in other strains of this parasite due to their different expression patterns, which warrants future research.

[Long-term oncological outcomes of laparoscopic versus abdominal surgery in stage Ⅰa1 （LVSI+）-Ⅰb1 cervical cancer patients with different tumor size: a big database in China]

Objective: To compare the long-term oncological outcomes between laparoscopic and abdominal surgery in stage Ⅰa1 （lymph-vascular space invasion-positive, LVSI⁺）- Ⅰb1 cervical cancer patients with different tumor sizes. Methods: Based on the Big Database of Clinical Diagnosis and Treatment of Cervical Cancer in China (1538 project database), patients with stage Ⅰa1 （LVSI⁺）-Ⅰb1 cervical cancer who treated by laparoscopic or abdominal surgery were included. The 5-year overall survival (OS) and 5-year disease-free survival (DFS) between the two surgical approaches were compared under 1∶1 propensity score matching (PSM) in different tumor diameter stratification. Results: (1) A total of 4 891 patients with stage Ⅰa1 （LVSI⁺）-Ⅰb1 cervical cancer who underwent laparoscopy or laparotomy from January 1, 2009 to December 31, 2016 were included in the 1538 project database. Among them, 1 926 cases in the laparoscopic group and 2 965 cases in the abdominal group. There were no difference in 5-year OS and 5-year DFS between the two groups before matching. Cox multivariate analysis suggested that laparoscopic surgery was associated with lower 5-year DFS (HR=1.367, 95%CI: 1.105-1.690, P=0.004). After 1∶1 PSM matching, 1 864 patients were included in each group, and there was no difference in 5-year OS between the two groups （94.1% vs 95.4%, P=0.151）. While, the inferior 5-year DFS was observed in the laparoscopic group (89.0% vs 92.3%, P=0.004). And the laparoscopic surgery was associated with lower 5-year DFS (HR=1.420, 95%CI: 1.109-1.818, P=0.006). (2) In stratification analysis of different tumor sizes, and there were no difference in 5-year OS and 5-year DFS between the laparoscopic group and abdominal group in tumor size ≤1 cm, >1-2 cm and >2-3 cm stratification (all P>0.05). Cox multivariate analysis showed that laparoscopic surgery were not related to 5-year OS and 5-year DFS (P>0.05). In the stratification of tumor size >3-4 cm, there was no difference in 5-year OS between the two groups (P>0.05). The 5-year DFS in the laparoscopic group was worse than that in the abdominal group (75.7% vs 85.8%, P=0.025). Cox multivariate analysis suggested that laparoscopic surgery was associated with lower 5-year DFS (HR=1.705, 95%CI: 1.088-2.674, P=0.020). Conclusions: For patients with stage Ⅰa1 （LVSI⁺）-Ⅰb1 cervical cancer, laparoscopic surgery is associated with lower 5-year DFS, and the adverse effect of laparoscopic surgery on oncology prognosis is mainly reflected in patients with tumor size >3-4 cm. For patients with tumor sizes ≤1 cm, >1-2 cm and >2-3 cm, there are no difference in oncological prognosis between the two surgical approaches.

Effect of deletion of gra17 and gra23 genes on the growth, virulence, and immunogenicity of type II Toxoplasma gondii

The protozoan parasite Toxoplasma gondii secretes a number of dense granule proteins (GRAs) from the dense granule organelle to manipulate the host cell. Two of these effector proteins (GRA17 and GRA23) are involved in the trafficking of molecules between the parasitophorous vacuole (PV) and the host cell cytoplasm. However, their roles in establishing chronic infection remain obscured. In this study, CRISPR-Cas9 was used to delete gra17 or gra23 gene in T. gondii Pru strain (type II). The growth, the virulence, the ability to establish chronic infection, and the immunogenicity of the constructed mutant strains were investigated in Kunming mice. Pru:Δgra17 and Pru:Δgra23 mutants developed PVs with abnormal morphology and exhibited reduced growth rate, compared with the wild-type Pru strain. Deletion of gra17 abrogated acute infection and blocked cyst formation. Although the deletion of gra23 caused slight attenuation of the parasite virulence in mice, it caused a significant reduction in cyst formation. Immunization with Pru:Δgra17 induced high levels of IgG (IgG1 and IgG2a) antibodies and cytokines (interleukin-2 [IL-2], IL-10, IL-12, and interferon gamma [IFN-γ]), which conferred significant protection in mice challenged with virulent type I (RH), ToxoDB#9 (PYS) strains, or less virulent type II (Pru) strain of T. gondii. These findings show that GRA17 and GRA23 play important roles in T. gondii chronic infection and that irreversible deletion of gra17 in T. gondii type II Pru strain can be a viable option for stimulating protective immunity to T. gondii infection.

First Report of Chlamydia Seroprevalence and Risk Factors in Domestic Black-Boned Sheep and Goats in China

The Gram-negative bacteria of the genus Chlamydia cause a wide range of diseases in humans and animals. The seroprevalence of Chlamydia in domestic black-boned sheep and goats in China is unknown. In this survey, a total of 481 serum samples were collected randomly from domestic black-boned sheep and goats from three counties in Yunnan province, southwest China, from July to August 2017. The sera were examined by an indirect hemagglutination assay (IHA). Antibodies to Chlamydia were detected in 100/481 [20.79%, 95% confidence interval (CI), 17.16–24.42] serum samples (IHA titer ≥1:64). The Chlamydia seroprevalence ranged from 12.21% (95% CI, 7.81–16.61) to 30.89% (95% CI, 22.72–39.06) across different regions in Yunnan province, and the differences were statistically significant (P < 0.01). The seroprevalence in male domestic black-boned sheep and goats (28.64%; 95% CI, 22.36–34.92) was significantly higher than that in the females (15.25%; 95% CI, 11.05–19.45) (P < 0.01). However, there was no statistically significant difference in Chlamydia seroprevalence in domestic black-boned sheep and goats between ages and species (P > 0.05). To our knowledge, this is the first report of Chlamydia seroprevalence in domestic black-boned sheep and goats in Yunnan Province, southwest China. These data provide baseline information for future implementation of measures to control Chlamydia infection in these animals.

[Comparison of clinical and pathological features between severe acute respiratory syndrome and coronavirus disease 2019]

Severe acute respiratory syndrome (SARS) and coronavirus disease 2019 (COVID-19) shared similar pathogenetic, clinical and pathological features. Fever and cough were the most common symptoms of both diseases, while myalgia and diarrhea were less common in patients with COVID-19. Acute respiratory distress syndrome (ARDS) was the most severe pulmonary complication that caused high mortality rate. Histologically, diffuse alveolar damage (DAD) was the most characteristic finding in non-survivors with either SARS or COVID-19. Cases of patients died less than 10-14 days of disease duration demonstrated acute-phase DAD, while cases beyond 10-14 days of disease duration exhibited organizing-phase DAD in SARS. Meanwhile, organization and fibrosis were usually accompanied by exudation. Coronavirus was mostly detected in pneumocytes, but less in macrophages and bronchiolar epithelial cells. Hemorrhagic necrosis and lymphocyte depletion were found in lymph nodes and spleen in both SARS and COVID-19, indicating a pathological basis of lymphocytopenia. Thrombosis was commonly observed in small vessels and microvasculaturr in lungs accompanying DAD. Microthrombosis was also found in extrapulmonary organs in COVID-19, that was less reported in SARS. Damages in multiple extrapulmonary organs were observed, but coronavirus was not detected in some of those organs, indicating an alternative mechanism beyond viral infection, such as hypoxemia, ischemia and cytokine storm induced immunological injury. DAD due to viral infection and immunological injury, as well as multi-organ dysfunction and extensive microthrombus formation, brought huge challenge to the management of patients with severe SARS or COVID-19.

Serological evidence of Toxoplasma gondii and Neospora caninum infection in black-boned sheep and goats in southwest China

Toxoplasma gondii and Neospora caninum are two closely related protozoan parasites which can cause abortion and significant economic losses in sheep and goats. However, it is yet to know whether black-bone sheep and goats are infected with T. gondii and N. caninum in China. In the present investigation, the seroprevalence and risk factors of T. gondii and N. caninum infections in black-boned sheep and goats were investigated in Yunnan Province, subtropical southwest China between July and August of 2017. A total of 481 serum samples were tested for T. gondii antibodies using the Modified Agglutination Test (MAT), and 468 serum samples were examined for N. caninum antibodies by indirect Enzyme-Linked Immunosorbent Assay (iELISA). The overall seroprevalence of T. gondii in black-boned sheep and goats was 36.80% (177/481, 95% CI 32.49-41.11), and 40 out of 468 serum samples were N. caninum-seropositive (8.55%, 95% CI 6.02-11.08). There was significant difference in the seroprevalence of T. gondii infection in different regions (χ² = 19.869, df = 2, P<0.01). As for the seroprevalence of N. caninum infection, region (χ² = 8.558, df = 2, P<0.05), age (χ² = 16.631, df = 3, P < 0.01), gender (χ² = 11.219, df = 1, P < 0.01) and species (χ² = 8.673, df = 1, P < 0.01) were the risk factors. In addition, the seroprevalence of coinfection of T. gondii and N. caninum in black-boned sheep and goats was 3.63% (17/468, 95% CI 1.94-5.32). To our knowledge, this is the first report of T. gondii and N. caninum seroprevalence in black-boned sheep and goats in China, which provided base-line data for the execution of control strategies and measures against T. gondii and N. caninum infection in black-boned sheep and goats.

Characterization of the Role of Amylo-Alpha-1,6-Glucosidase Protein in the Infectivity of Toxoplasma gondii

In this study, we characterized the role of amylo-alpha-1,6-glucosidase (Aa16GL) in the biology and infectivity of Toxoplasma gondii, using Aa16GL-deficient parasites of type I RH and type II Prugniaud (Pru) strains. The subcellular localization of Aa16GL protein was characterized by tagging a 3 × HA to the 3′ end of the Aa16GL gene endogenous locus. Immunostaining of the expressed Aa16GL protein revealed that it is located in several small cytoplasmic puncta. Functional characterization of ΔAa16GL mutants using plaque assay, egress assay and intracellular replication assay showed that parasites lacking Aa16GL exhibit a slight reduction in the growth rate, but remained virulent to mice. Although PruΔAa16GL tachyzoites retained the ability to differentiate into bradyzoites in vitro, they exhibited slight reduction in their ability to form cysts in mice. These findings reveal new properties of Aa16GL and suggest that while it does not have a substantial role in mediating T. gondii infectivity, this protein can influence the formation of parasite cysts in mice.

Association analysis of rs2275913G>A and rs763780T>C interleukin 17 polymorphisms in Chinese women with cervical cancer

We conducted a case-control study with a relatively large sample size, and investigated the association between rs2275913G>A and rs763780T>C and the risk of cervical cancer. Three hundred and six newly diagnosed patients with histologically confirmed cervical cancer and 354 cancer-free control subjects were recruited from the Forestry General Hospital between May 2011 and May 2014. The gene polymorphisms rs2275913G>A and rs763780T>C were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. By unconditional logistic regression analysis, our study found that the AA genotype and the A allele of rs2275913 were associated with a higher risk of cervical cancer compared with the wild-type genotype, and the ORs (95%CIs) were 2.84 (1.57-5.23) and 1.55 (1.22-1.97), respectively. Compared with the G allele, the A allele of rs699947 was associated with a significantly increased risk of cervical cancer in subjects above 20 years and who were positive for human papillomavirus 16 (HPV-16) or HPV-18 infection. Patients with the A allele of rs2275913 had increased risk of cervical cancer, regardless of the number of births they had experienced or their smoking habits. We suggest that rs2275913 may play a role in the etiology of cervical cancer, although further large-sample studies are needed to confirm these observations.

Spontaneous emission modulation of colloidal quantum dots via efficient coupling with hybrid plasmonic photonic crystal

The spontaneous emission of colloidal CdSe/ZnS quantum dots (CQDs) modified by the hybrid plasmonic-photonic crystal is reported in this paper. By using a spin coater, the spatial overlap between CQDs and the surface resonance modes in this quasi-2D crystal slab is achieved. In this case, the coupling efficiency of them is enhanced greatly and most excited CQDs radiate through the surface modes. Consequently, despite the low refractive index contrast of our hybrid structure, the directionality of spontaneous emission, increased radiative probability and narrowed full width at half maximum of emission peak are all clearly observed by our home-made microscopic angle-resolved spectroscopy and time-resolved photoluminescence system. Our results manifest that the quasi-2D hybrid plasmonic-photonic crystal is an ideal candidate to tailor the radiative properties of CdSe/ZnS CQDs, which might be significant for the applications of light emitting devices.

Stability of daphnoretin in vitro

The stability of daphnoretin in sodium phosphate buffers at different pH and temperature, and in different biological samples at 37 degrees C was investigated using HPLC with UV detector set at 345 nm. Daphnoretin degraded rapidly in alkaline environment and was stable in acidic environment. Daphnoretin was stable in simulated gastrointestinal liquid, stomach contents, gastric mucosa and colon contents; it was unstable in plasma, liver homogenates, small intestine contents, small intestinal mucosa and blind gut contents. The stability of daphnoretin in plasma and other biomaterials could have a significant impact on its absorption.

Hollow fiber liquid-phase microextraction for the determination of nimesulide in human plasma and its application to a pharmacokinetic study

A hollow fiber liquid-phase microextraction (HF-LPME) method in combination with HPLC-UV for the determination of nimesulide in human plasma was developed and validated. A small volume of dihexyl ether contained within a polypropylene hollow fiber was used for the extraction of nimesulide from acidified plasma solutions. Factors affecting the extraction efficiency were optimized and discussed. With HPLC-UV as the end analysis technique, the procedure was validated for nimesulide in the concentration range of 50-5000 ng/mL. The intra- and inter-assay precisions were less than 9.1%, and accuracy was within 3.2%. The lower limit of quantification (LLOQ) was 50 ng/mL. Enrichment factor from 144-fold to 156-fold was achieved at three quality control (QC) concentrations. The mean extraction recovery was greater than 41.2%. This method was successfully applied for the evaluation of pharmacokinetics of nimesulide after single oral doses of 100 mg nimesulide to six healthy Chinese volunteers.

Composition design for Laves phase-related body-centered cubic-V solid solution alloys with large hydrogen storage capacities

This paper analyzes the characteristics of alloy compositions with large hydrogen storage capacities in Laves phase-related body-centered cubic (bcc) solid solution alloy systems using the cluster line approach. Since a dense-packed icosahedral cluster A(6)B(7) characterizes the local structure of AB(2) Laves phases, in an A-B-C ternary system, such as Ti-Cr (Mn, Fe)-V, where A-B forms AB(2) Laves phases while A-C and B-C tend to form solid solutions, a cluster line A(6)B(7)-C is constructed by linking A(6)B(7) to C. The alloy compositions with large hydrogen storage capacities are generally located near this line and are approximately expressed with the cluster-plus-glue-atom model. The cluster line alloys (Ti(6)Cr(7))(100-x)V(x) (x = 2.5-70 at.%) exhibit different structures and hence different hydrogen storage capacities with increasing V content. The alloys (Ti(6)Cr(7))(95)V(5) and Ti(30)Cr(40)V(30) with bcc solid solution structure satisfy the cluster-plus-glue-atom model.

Microcalorimetric study on the growth and metabolism of microencapsulated microbial cell culture

The rate of heat output is one of the suitable measurements of metabolic activity of the organism or its parts, down to the cellular or even the sub-cellular levels. In this paper, microcalorimetry was first applied to study the metabolic activity of microbial in both alginate-polylysine-alginate and alginate-chitosan-alginate microencapsulated cultures as well as in free non-encapsulated culture. The organisms used for the measurements were Escherichia coli and Saccharomyces cerevisiae. As a result of this work, it was found that, despite E. coli cell in free non-encapsulated culture has the highest metabolic rate due to the highest value of heat output, the proliferation of the cells terminates quickly with a lowest biomass formed. And we found also an obviously longer stationary phase in microencapsulated culture. As far as S. cerevisiae was concerned, it was found that there was also the highest value of heat output in free non-encapsulated culture, but the cell density was lower than that in microencapsulated culture. On account of the microcalorimetric and metabolic measurements, it can be concluded that more substrate can be used to convert to biomass in microencapsulated culture which means a higher biomass yield existed.

Human papillomavirus infection in Shanxi Province, People's Republic of China: a population-based study

To investigate the prevalence of, and risk factors for, cervical infection with human papillomavirus (HPV) in the rural province of Shanxi, People's Republic of China, which has relatively high cervical cancer mortality rates, we interviewed and obtained cervical cell samples from 662 women aged 15–59 years. A total of 24 different HPV types were identified using a GP5+/6+-based PCR assay able to detect 44 different HPV types. Human papillomavirus prevalence was 14.8% overall and 9.6% among women without cervical abnormalities (14.2 and 8.9%, respectively, age standardised to the world standard population). Multiple-type infections accounted for 30.6% of all infections. By far the most commonly found type was HPV16 (5.7% of all women and 38.8% of HPV-positive women), followed by HPV 58, 52, 33 and 18. Unlike most previous studies published, HPV prevalence was lower among women younger than 35 years (8.7%) than those older than 35 years (17.8%). High-risk HPV types predominated in all age groups. Although low-risk HPV types were rare in young women, they became more common with increasing age. 92.3% of women with cervical intraepithelial neoplasia grade 3 were infected with high-risk HPV types, but none with low-risk types only. No significant difference in HPV positivity was observed by educational level, sexual habits, reproductive history or use of contraceptive methods in this rural low-income Chinese population.

BCL-2 inhibits B7-induced MHC-unrestricted cytolysis mediated by a human NK cell line

Recent work demonstrated that B7 expression by tumor cells can enhance antitumor immune responses. However, the B7 molecule is expressed abundantly on most non-Hodgkin's B-cell lymphomas and solid lymphoid tumors. How these tumor cells escape from immune surveillance mechanisms remains unclear. Lately, it has become clear that bcl-2 oncogene is overexpressed in a wide variety of human cancers and renders tumor cells more resistant to cytolytic T-cells (CTL) mediated cytotoxicity. We cloned B7 and B7/Bcl-2 transfectants and compared their susceptibilities to a human natural killer (NK) cell line and normal NK cells. The results demonstrate that Bcl-2 oncoprotein in tumor cells blocks B7-induced cytolysis mediated by a NK cell line and NK cells. Thus, they suggest that Bcl-2 oncoprotein plays a role in tumor avoidance of effective antitumor cytotoxicity.

Structural determinants of ion selectivity in brain calcium channel

Glutamic acid residues in the SS2 segment of the internal repeats III and IV of the brain calcium channel BI were subjected to single point mutations. The mutant channels were tested for macroscopic current properties and sensitivities to inorganic blockers. The mutation that replaces glutamic acid 1,469 with glutamine altered ion-selection properties and strongly reduced the sensitivity to Cd2+, whereas the analogous mutation of glutamic acid 1,765 exerted smaller effects on ion-selection properties. Our results indicate that these glutamic acid residues, equivalently positioned in the aligned sequences, play different roles in the selective permeability of the calcium channel.

Vessel pathology and its clinical significance in toe transfer

One hundred cases of toe transfer were subjected to histopathologic vessel examination. Results indicated that vascular injuries are crucially responsible for perioperative and postoperative crisis. A thorough resection of the abnormal vessel segment can prevent circulatory crisis and elevate the survival rate.