Multigenerational Effects of Heavy Metals on Feeding,Growth, Initial Reproduction and Antioxidants in Caenorhabditis elegans

Earlier studies showed that toxicities of excessive metals lasted over generations. Yet, these studies mainly employed one-generation exposure, and the effects of multigenerational challenges need further studies. Presently, Caenorhabditis elegans were exposed to cadmium, copper, lead and zinc for four consecutive generations (G1 to G4) at environmental concentrations. The feeding, growth, initial reproduction, superoxide dismutase (SOD) and catalase (CAT) were determined. All data were represented in the percentage of that in control (POC), and POC in the control was normalized to 100%. In G1 and G2, the POC values in feeding, growth and initial reproduction were generally within 10% of the control (100%), indicating non-significant effects. The POC values in SOD and CAT were significantly higher than 100%, showing stimulatory effects. In G3 and G4, the POC values in feeding, growth and initial reproduction were significantly lower than 100%, showing inhibitory effects which were more severe in G4 than in G3. Meanwhile, SOD and CAT continuously showed stimulatory effects, and the stimulatory effects on SOD increased from G1 to G4. The effects with multigenerational challenges were different from those in one-generation exposure. The effects in later generations demonstrated the importance of multigenerational challenges in judging long-term influences of metals.     

Inhibition of TREM-1 and Dectin-1 Alleviates the Severity of Fungal Keratitis by Modulating Innate Immune Responses

Purpose

To explore the possibility that inhibiting triggering receptor expressed on myeloid cells-1 (TREM-1) and Dendritic cell-associated C-type lectin-1(Dectin-1) could modulate the innate immune response and alleviate the severity of corneal fungal keratitis.

Method

TREM-1 and Dectin-1 expression was detected in fungus-infected human corneal specimens by real-time PCR. C57BL/6 (B6) mice were injected with Aspergillus fumigatus and divided into 4 groups that received subconjunctival injections of PBS and IgG as a control (group I), mTREM-1/IgG fusion protein (group II), the soluble β-glucan antagonist laminarin (group III), or mTREM-1/Fc and laminarin (group IV). Corneal virulence was evaluated based on clinical scores. TREM-1 and Dectin-1 mRNA levels were assayed using real-time PCR. The distribution patterns of TREM-1, Dectin-1 and cellular infiltrates in fungus-infected corneas were examined by immunohistochemistry. Moreover, changes in T Helper Type1 (Th1)-/ T Helper Type1 (Th2)- type cytokines and proinflammatory cytokines were measured.

Results

The expression of TREM-1 and Dectin-1 increased significantly and correlated positively with the progression of fungal keratitis. Most infiltrated cells were neutrophils and secondarily macrophages in infected cornea. The clinical scores decreased after interfering with TREM-1 and Dectin-1 expression in infected mouse corneas. Levels of Th1-type cytokines including interleukin-12 (IL-12), IL-18 and interferon-γ (IFN-γ) were decreased in the cornea, while the levels of Th2-type cytokines, including IL-4, IL-5 and IL-10, showed obvious increases.

Conclusion

TREM-1 and Dectin-1 function concurrently in the corneal innate immune response by regulating inflammatory cytokine expression in fungal keratitis. Inhibition of TREM-1 and Dectin-1 can alleviate the severity of corneal damage by downregulating the excessive inflammatory response.     

Urban and Rural Differences of Acute Cardiovascular Disease Events: A Study from the Population-Based Real-Time Surveillance System in Zhejiang,China in 2012

Zhejiang province, China, has implemented a population based, real-time surveillance system that tracks acute cardiovascular diseases (CVDs) events since 2001. This study aimed to describe the system and report CVD incidence, mortality and case-fatality between urban and rural areas in Zhejiang in 2012. The surveillance system employs a stratified random sampling method covering all permanent residents of 30 counties/districts in Zhejiang. Acute CVD events such as coronary heart disease (CHD) and stroke were defined, registered and reviewed based on the adapted MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) definitions. Data were collected from health facilities, vital registries, supplementary surveys, and additional investigations, and were checked for data quality before input in the system. We calculated the rates and compared them by gender, age and region. In 2012, the incidence, mortality and case-fatality of total acute CVD events were 367.0 (CHD 59.1, stroke 307.9), 127.1 (CHD 43.3, stroke 83.8) per 100,000 and 34.6% (CHD 73.2%, stroke 27.2%), respectively. Compared with rural areas, urban areas reported higher incidence and mortality but lower case-fatality rates for CHD (P<0.001), while lower incidence but higher mortality and case-fatality rates for stroke (P<0.001). We found significant differences on CHD and stroke epidemics between urban and rural areas in Zhejiang. Special attentions need to be given to stroke control, especially in rural areas.     

Mycobacterium leprae-Infected Macrophages Preferentially Primed Regulatory T Cell Responses and Was Associated with Lepromatous Leprosy

Background

The persistence of Mycobacterium leprae (M. leprae) infection is largely dependent on the types of host immune responses being induced. Macrophage, a crucial modulator of innate and adaptive immune responses, could be directly infected by M. leprae. We therefore postulated that M. leprae-infected macrophages might have altered immune functions.

Methodology/Principal Findings

Here, we treated monocyte-derived macrophages with live or killed M. leprae, and examined their activation status and antigen presentation. We found that macrophages treated with live M. leprae showed committed M2-like function, with decreased interleukin 1 beta (IL-1beta), IL-6, tumor necrosis factor alpha (TNF-alpha) and MHC class II molecule expression and elevated IL-10 and CD163 expression. When incubating with naive T cells, macrophages treated with live M. leprae preferentially primed regulatory T (Treg) cell responses with elevated FoxP3 and IL-10 expression, while interferon gamma (IFN-gamma) expression and CD8⁺ T cell cytotoxicity were reduced. Chromium release assay also found that live M. leprae-treated macrophages were more resistant to CD8⁺ T cell-mediated cytotoxicity than sonicated M. leprae-treated monocytes. Ex vivo studies showed that the phenotype and function of monocytes and macrophages had clear differences between L-lep and T-lep patients, consistent with the in vitro findings.

Conclusions/Significance

Together, our data demonstrate that M. leprae could utilize infected macrophages by two mechanisms: firstly, M. leprae-infected macrophages preferentially primed Treg but not Th1 or cytotoxic T cell responses; secondly, M. leprae-infected macrophages were more effective at evading CD8⁺ T cell-mediated cytotoxicity.     

Model of the pathway of −1 frameshifting: Long pausing

It has been characterized that the programmed ribosomal ?1 frameshifting often occurs at the slippery sequence on the presence of a downstream mRNA pseudoknot. In some prokaryotic cases such as the dnaX gene of Escherichia coli, an additional stimulatory signal—an upstream, internal Shine–Dalgarno (SD) sequence—is also necessary to stimulate the efficient ?1 frameshifting. However, the molecular and physical mechanism of the ?1 frameshifting is poorly understood. Here, we propose a model of the pathway of the ?1 translational frameshifting during ribosome translation of the dnaX ?1 frameshift mRNA. With the model, the single-molecule fluorescence data (Chen et al. (2014) [29]) on the dynamics of the shunt either to long pausing or to normal translation, the tRNA transit and sampling dynamics in the long-paused rotated state, the EF-G sampling dynamics, the mean rotated-state lifetimes, etc., are explained quantitatively. Moreover, the model is also consistent with the experimental data (Yan et al. (2015) [30]) on translocation excursions and broad branching of frameshifting pathways. In addition, we present some predicted results, which can be easily tested by future optical trapping experiments.     

Comparative genomic and protein sequence analyses of the chemotaxis system of Azorhizobium caulinodans北大核心CSCD

［Objective］ Azorhizobium caulinodans ORS571 can fix nitrogen not only as a free-living organism and an associative-symbiotic bacterium by colonizing the root surface of non-leguminous plants, but also as a symbiotic bacterium by interacting with leguminous plant Sesbania rostrata.Due to its ability to grow and fix nitrogen under three conditions, A.caulinodans uses sophisticated chemotaxis signal transduction systems to transform environmental cues into corresponding behavioral responses.Chemotaxis appears crucial for the growth of A.caulinodansin complicated environment and the construction of associative relationship with the plant.However, little is known about the chemotactic pathway of A.caulinodans.Thus, our study aimed to compare the chemotaxis-like genes of A.caulinodans with those of well-studied species.［Methods］ NCBI protein BLAST was used for searching sequence similarity with default parameter values against the genomes of A.caulinodans.HMMER3, based on Pfam database, was used for comparative analyses of methyl-accepting chemotaxis protein （MCP）.［Results］ There was a major chemotaxis cluster in A.caulinodans and the CheR methylated MCPs independently of pentapeptide motif.There were 43 MCP homologs containing diverse signal-sensing architectures in A.caulinodans.In addition,cytoplasmic domains of these MCPs were all composed of 38 heptad repeats.［Conclusion］ Despite the extremely high homology presented between the chemotactic system of A.caulinodans and those of well-studied species, A.caulinodans shows its own unique characteristics.The classification of these chemotactic pathways by comparative genomics enables us to better understand how A.caulinodansresponds to changes in environment via exquisite signal transductions in chemotaxis system.     

和厚朴酚抑制耐甲氧西林金黄色葡萄球菌生物被膜形成

【目的】研究和厚朴酚(HNK)抑制MRSA生物被膜(BF)形成的作用机制。【方法】使用TTC法测定了HNK对供试菌株BF的形成和成熟BF的抑制作用;刚果红平板法定性检测了HNK对PIA合成的影响;分光光度法测定了HNK对供试菌株eDNA释放量的影响;RT-PCR技术检测了HNK对供试菌株icaA、cidA以及agrA基因表达量的影响。【结果】HNK对MRSA 41573 BF的形成和成熟BF均有较强的抑制作用,其中,HNK抑制MRSA 41573 BF形成的MIC和MBC分别为10μg/mL和20μg/mL;抑制成熟BF的MIC和MBC分别为50μg/mL和100μg/mL。当用亚抑菌浓度的HNK与万古霉素联合作用后,可显著提高成熟BF对万古霉素的敏感性。HNK能显著抑制PIA的合成,且呈浓度剂量依赖。HNK能抑制供试菌株eDNA的释放量,其中1/8 MIC的HNK作用供试菌株16 h后,与对照组相比,e DNA的释放量降低了28.3%。HNK可抑制供试菌株BF形成的相关基因,其中1/2 MIC的HNK作用供试菌株16 h后,与对照相比,icaA的表达量降低了59.1%,cidA的表达量降低了56%,agrA的表达量降低了72.3%。【结论】HNK能显著抑制MRSA 41573 BF的形成,其作用机制主要是通过抑制icaA和cidA基因表达量,影响PIA和eDNA的合成,进而抑制BF的形成。此外HNK也可通过调控细菌的QS系统影响BF的形成。