Evaluation of ompA and pgtE genes in determining pathogenicity in Salmonella enterica serovar Enteritidis

Salmonella enterica subsp. enterica serovar Enteritidis (S. Enteritidis) is a major causative agent of gastroenteritis in humans. This important food-borne pathogen also colonises the intestinal tracts of poultry and can spread systemically, especially in chickens. To identify the S. Enteritidis virulence genes involved in infection and colonisation of chickens, chromosomal deletion mutants of the ompA and pgtE genes, which encode essential components of omptins, were constructed. There were no significant differences between the wild-type and ompA and pgtE mutants in a series of in vitro assays, including an intracellular survival assay, survival in specific-pathogen-free (SPF) chicken serum, and in vitro competition assays. In contrast, in vivo competition assays revealed that ompA and pgtE mutants underwent attenuated growth in liver, cardiac blood, spleen, lung, and kidney compared to a wild-type strain (CVCC3378). When tested in SPF chickens, ompA or pgtE gene inactivation substantially reduced organ colonisation and delayed systemic infection compared with the wild-type strain. Colonisation was restored in S. Enteritidis mutants by reintroduction of the whole ompA or pgtE gene with the native promoters. The results of this study demonstrate that ompA and pgtE play an important role in the pathogenesis of S. Enteritidis and its ability to infect chickens.

Endogenous Retroelements and the Host Innate Immune Sensors

The ability to distinguish between self and nonself is the fundamental basis of the immune system in all organisms. The conceptual distinction between self and nonself, however, breaks down when it comes to endogenous retroviruses and other retroelements. While some retroelements retain the virus-like features including the capacity to replicate and reinvade the host genome, most have become inactive through mutations or host epigenetic silencing. And yet, accumulating evidence suggests that endogenous retroelements, both active and inactive, play important roles not only in pathogenesis of immune disorders, but also in proper functioning of the immune system. This review discusses the recent development in our understanding of the interaction between retroelements and the host innate immune system. In particular, it focuses on the impact of retroelement transcripts on the viral RNA sensors such as Toll-like receptors, RIG-I-like receptors, protein kinase R, and the inflammasomes.

Comprehensive analysis of TEM methods for LiFePO4/FePO4 phase mapping: spectroscopic techniques (EFTEM, STEM-EELS) and STEM diffraction techniques (ACOM-TEM)

Transmission electron microscopy (TEM) has been used intensively in investigating battery materials, e.g. to obtain phase maps of partially (dis)charged (lithium) iron phosphate (LFP/FP), which is one of the most promising cathode material for next generation lithium ion (Li-ion) batteries. Due to the weak interaction between Li atoms and fast electrons, mapping of the Li distribution is not straightforward. In this work, we revisited the issue of TEM measurements of Li distribution maps for LFP/FP. Different TEM techniques, including spectroscopic techniques (energy filtered (EF)TEM in the energy range from low-loss to core-loss) and a STEM diffraction technique (automated crystal orientation mapping (ACOM)), were applied to map the lithiation of the same location in the same sample. This enabled a direct comparison of the results. The maps obtained by all methods showed excellent agreement with each other. Because of the strong difference in the imaging mechanisms, it proves the reliability of both the spectroscopic and STEM diffraction phase mapping. A comprehensive comparison of all methods is given in terms of information content, dose level, acquisition time and signal quality. The latter three are crucial for the design of in-situ experiments with beam sensitive Li-ion battery materials. Furthermore, we demonstrated the power of STEM diffraction (ACOM-STEM) providing additional crystallographic information, which can be analyzed to gain a deeper understanding of the LFP/FP interface properties such as statistical information on phase boundary orientation and misorientation between domains.

Association of fat-mass and obesity-associated gene FTO rs9939609 polymorphism with the risk of obesity among children and adolescents: a meta-analysis

OBJECTIVE

To elucidate the association of fat-mass and obesity-associated gene (FTO) rs9939609 polymorphism with obesity among children and adolescents.

METHODS

A literature search was conducted in PubMed, MEDLINE, Springer, and Google scholar to identify eligible studies. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used for four models: co-dominant model (AA vs. TT, AT vs. TT), dominant model (AA + AT vs. TT), recessive model (AA vs. AT + TT), and allelic model (A vs. T). Subgroup analyses stratified by ethnicity (Caucasian, others) and participants (children, children and adolescents) were assessed under allelic model. The heterogeneity and publication bias were examined.

RESULTS

This meta-analysis included 12 eligible studies consisting 5,000 cases and 9,853 controls. The results revealed that FTO rs9939609 polymorphism was significantly associated with the increased risk of obesity in co-dominant model (AA vs. TT: OR = 1.91, 95% CI: 1.47-2.48, p < 0.01; AT vs. TT: OR = 1.18, 95% CI: 1.02-1.38, p = 0.03), dominant model (AA + AT vs. TT: OR = 1.47, 95% CI: 1.35-1.59, p < 0.01), recessive model (AA vs. AT + TT: OR = 1.79, 95% CI: 1.47-2.17, p < 0.01), and allelic model (A vs. T: OR = 1.39, 95% CI: 1.22-1.58, p < 0.01). Similar results were obtained for the subgroup analyses stratified by ethnicity and participants under allelic model.

CONCLUSIONS

FTO rs9939609 polymorphism is associated with the increased risk of obesity among children and adolescents, especially the homozygous carriers.

A novel microbead-based microfluidic device for rapid bacterial identification and antibiotic susceptibility testing

Effective treatment of infectious diseases depends on the ability to rapidly identify the infecting bacteria and the use of sensitive antibiotics. The currently used identification assays usually take more than 72 h to perform and have a low sensitivity. Herein, we present a microbead-based microfluidic platform that is highly sensitive and rapid for bacterial detection and antibiotic sensitivity testing. The platform includes four units, one of which is used for bacterial identification and the other three are used for susceptibility testing. Our results showed that Escherichia coli O157 at a cell density range of 10(1)-10(5) CFU/μL could be detected within 30 min. Additionally, the effects of three antibiotics on E. coli O157 were evaluated within 4-8 h. Overall, this integrated microbead-based microdevice provides a sensitive, rapid, reliable, and highly effective platform for the identification of bacteria, as well as antibiotic sensitivity testing.

Resonantly pumped single-mode channel waveguide Er:YAG laser with nearly quantum defect limited efficiency

We demonstrated the continuous-wave operation of a resonantly pumped Er:YAG single-mode channel waveguide laser with diffraction-limited output and nearly quantum defect limited efficiency. Using a longitudinally core-pumped, nearly square (61.2 μm×61.6 μm) Er3+:YAG waveguide embedded in an undoped YAG cladding, an output power of 9.1 W with a slope efficiency of 92.8% (versus absorbed pump power) has been obtained. To the best of our knowledge, this optical-to-optical efficiency is the highest ever demonstrated for a channel waveguide laser.

Influence of the XbaI polymorphism in the estrogen receptor-α gene on human spermatogenic defects

Polymorphisms of estrogen receptor (ER) genes have been implicated in male infertility, but studies of this association have produced conflicting results. The present study was conducted to examine whether polymorphisms within the ERα and ERβ genes are susceptibility factors for human male idiopathic infertility in Chinese men. We investigated the association between the ERα gene gene and PvuII and XbaI polymorphisms and the ERβ gene and RsaI and AluI polymorphisms and idiopathic male infertility in Han Chinese men. A total of 204 men with oligozoospermia (sperm count <20 x 10(6)/mL) or azoospermia and 252 fertile control men were included in this study. The analysis revealed a strong association between the XbaI genotype distribution and impaired spermatogenesis (P = 0.0018). The frequency of the G allele was significantly lower in patients than in controls (P = 0.003). Furthermore, serum levels of follicle-stimulating hormone and luteinizing hormone in XbaI AA carriers were significantly higher than those in AG or GG carriers. Our findings further support a possible role of ERα in male infertility. Further studies are needed to replicate our findings, as well as to elucidate more fully the biological mechanisms of the modulation of ERα on human spermatogenesis.

Effect of triptolide on progesterone production from cultured rat granulosa cells

Triptolide(CAS 38748-32-2), a major active component of Tripterygium wilfordii Hook F (TWHF), is known to have multiple pharmacological activities. However, studies have also shown that triptolide is highly disrupt to the reproductive system by disrupting normal steroid hormone signaling. In the present study, we investigated the effect of triptolide (5, 10, or 20 nM for 24 h) on progesterone production by rat granulosa cells. Triptolide inhibited both basal and human chorionic gonadotropin (HCG)- and 8-bromo-cAMP-stimulated progesterone production as revealed by RIA assay. Furthermore, the HCG-evoked increase in cellular cAMP content was also inhibited by triptolide, indicating that disruption of the cAMP/PKA signaling pathway may mediate the deleterious effects of triptolide on progesterone regulation. In addition, triptolide inhibited 25-OH-cholesterol-stimulated progesterone production, suggesting that activity of the P450 side chain cleavage (P450scc) enzyme was also be inhibited by triptolide. Western blot and quantitative real-time PCR (qRT-PCR) assays further revealed that triptolide decreased mRNA and protein expression of P450scc and the steroidogenic regulatory (StAR) protein in granulosa cells. In contrast, cell viability tests using 3-(4,5-dimethyl-thiazol-2-yl)-2,5- diphenyl-tetrazolium bromide (MTT) indicated that triptolide did not cause measurable cell death at doses that suppressed steroidogenesis. The reproductive toxicity of triptolide may be caused by disruption of cAMP/PKA-mediated expression of a number of progesterone synthesis enzymes or regulatory proteins, leading to reduced progesterone synthesis and reproductive dysfunction.

Expression profiles of seven channel catfish antimicrobial peptides in response to Edwardsiella ictaluri infection

Using quantitative polymerase chain reaction (QPCR), the relative transcriptional levels of seven channel catfish antimicrobial peptide (AMP) genes (NK-lysin type 1, NK-lysin type 2, NK-lysin type 3, bactericidal permeability-increasing protein, cathepsin D, hepcidin and liver-expressed AMP 2) in response to Edwardsiella ictaluri infection were determined. None of the AMP genes tested was significantly upregulated at 2 h post-infection. Hepcidin was the only one that was significantly (P<0.05) upregulated at 4, 6 and 12 h post-infection. At 24 and 48 h post-infection, four AMPs (hepcidin, NK-lysin type 1, NK-lysin type 3 and cathepsin D) were significantly (P<0.05) upregulated. Among all the AMPs that were significantly upregulated at different time points, hepcidin at 4, 6 and 12 h post-infection was upregulated the most. When catfish were injected with different doses of E. ictaluri, all lethal doses were able to induce significant (P <0.05) upregulation of hepcidin in the posterior kidney, whereas sublethal doses failed to induce any significant upregulation of hepcidin. In vitro growth studies revealed that the presence of synthetic hepcidin peptide at a concentration of 16 μm or higher significantly inhibited the cell proliferation of E. ictaluri. Taken together, our results suggest that hepcidin might play an important role in the channel catfish defence against E. ictaluri infection.

Microbialites and global environmental change across the Permian-Triassic boundary: a synthesis

Permian-Triassic boundary microbialites (PTBMs) are thin (0.05-15 m) carbonates formed after the end-Permian mass extinction. They comprise Renalcis-group calcimicrobes, microbially mediated micrite, presumed inorganic micrite, calcite cement (some may be microbially influenced) and shelly faunas. PTBMs are abundant in low-latitude shallow-marine carbonate shelves in central Tethyan continents but are rare in higher latitudes, likely inhibited by clastic supply on Pangaea margins. PTBMs occupied broadly similar environments to Late Permian reefs in Tethys, but extended into deeper waters. Late Permian reefs are also rich in microbes (and cements), so post-extinction seawater carbonate saturation was likely similar to the Late Permian. However, PTBMs lack widespread abundant inorganic carbonate cement fans, so a previous interpretation that anoxic bicarbonate-rich water upwelled to rapidly increase carbonate saturation of shallow seawater, post-extinction, is problematic. Preliminary pyrite framboid evidence shows anoxia in PTBM facies, but interbedded shelly faunas indicate oxygenated water, perhaps there was short-term pulsing of normally saturated anoxic water from the oxygen-minimum zone to surface waters. In Tethys, PTBMs show geographic variations: (i) in south China, PTBMs are mostly thrombolites in open shelf settings, largely recrystallised, with remnant structure of Renalcis-group calcimicrobes; (ii) in south Turkey, in shallow waters, stromatolites and thrombolites, lacking calcimicrobes, are interbedded, likely depth-controlled; and (iii) in the Middle East, especially Iran, stromatolites and thrombolites (calcimicrobes uncommon) occur in different sites on open shelves, where controls are unclear. Thus, PTBMs were under more complex control than previously portrayed, with local facies control playing a significant role in their structure and composition.

Evaluation of an in vitro cell assay to select attenuated bacterial mutants of Aeromonas hydrophila and Edwardsiella tarda to channel catfish

AIMS

To evaluate the feasibility of using an in vitro cell assay to select attenuated bacterial mutants.

METHODS AND RESULTS

Using catfish gill cells G1B, the feasibility of using an in vitro assay instead of in vivo virulence assay using live fish to select attenuated bacterial mutants was evaluated in this study. Pearson correlation analysis between in vitro virulence to G1B cells and in vivo virulence of Aeromonas hydrophila and Edwardsiella tarda revealed that there was a significant correlation between the two (r = -0.768, P value = 3.7 × 10(-16)).

CONCLUSIONS

The in vitro cell assay might be initially used to screen large quantities of bacteria to select attenuated mutants of catfish pathogens.

SIGNIFICANCE AND IMPACT OF THE STUDY

The in vitro cell assay using catfish gill cells to identify attenuated mutants of catfish pathogens will reduce cost involved in the in vivo virulence assay that requires many fish and aquariums.

An in vitro screening method to evaluate chemicals as potential chemotherapeutants to control Aeromonas hydrophila infection in channel catfish

AIMS

To develop an in vitro screening method to be used for identifying potential effective chemotherapeutants to control Aeromonas hydrophila infections.

METHODS AND RESULTS

Using catfish gill cells G1B and four chemicals (hydrogen peroxide, sodium chloride, potassium permanganate and D-mannose), the feasibility of using an in vitro screening method to identify potential effective chemotherapeutants was evaluated in this study. In vitro screening results revealed that, at concentration of 100 mg l⁻¹, H₂O₂ was the only chemical tested that was able to completely abolish the attachment and invasion of Aer. hydrophila to catfish gill cells. In vivo virulence studies using live channel catfish through bath immersion confirmed that H₂O₂ was the only chemical tested that was able to significantly (P < 0·001) reduce the mortality (from 90 or 100% to 0 or 20%) caused by Aer. hydrophila infections.

CONCLUSIONS

The in vitro screening method using catfish gill cells G1B could be used to initially identify potential effective chemotherapeutants to control Aer. hydrophila.

SIGNIFICANCE AND IMPACT OF THE STUDY

An in vitro screening method using catfish gill cells to identify potential effective chemotherapeutants described here will cut cost in research compared with the method of using live fish to screen lead compounds for fish disease control.

First-principles study of NO adsorbed Ni(100) surface

The geometric, electronic and magnetic properties of NO molecules adsorbed on the Ni(100) surface are investigated by the first-principles calculation on the basis of the density functional theory (DFT). The NO molecules are predicted to be chemisorbed at hollow site with an upright configuration at 0.125 ML and 0.5 ML coverages. After adsorption, the magnetic moment is significantly suppressed for surface Ni atom and almost quenched for NO molecule. This behavior can be reasonably explained by the difference of the backdonation process between the spin-up and spin-down electronic states, which is demonstrated by the spin-resolved differential charge density map.

107. RESPONSES OF THE PREIMPLANTATION EMBRYO TO DEFINED GENOTOXIC STRESSES

Genotoxic cellular stressors induce damage to the structure of DNA. This potentially compromises the genetic integrity of the cell. Such damage is particularly dangerous in the early embryo since transmission of defects can affect most cells in the body. Canonical responses of cells to such stress include delaying or blocking mitosis to allow DNA repair to occur or induction of cell death (apoptosis) to ensure that damage is not propagated. To date there have been only limited studies of the response of the preimplantation embryo to genotoxic stress. Ultra violet (UV) irradiation typically induces single strand DNA breaks while drugs such as the chemotherapeutic cisplatin commonly induce double strand breaks. ATM (Ataxia telangiectasia mutated) and ATR (Ataxia telangiectasia and rad3 related) are checkpoint kinase that mediate early responses of the cell to DNA damage. ATM primarily responds to DNA double strand breaks while ATR typically responds to single strand breaks and stalled replication forks. However, ATM and ATR may have partially overlapping and complementary functions. Both kinases can exert P53 dependent and independent responses. ATR protein was detected by immunofluorescence in all preimplantation stages up to the morulae stage. ATM protein was detected in oocytes and all stages. Cisplatin or UV-irradiation at the 2-cell stage caused increased nuclear staining of both ATM and ATR. UV-irradiation of 2-cell embryos induced irreversible, ATR-dependent, P53-independent cell-cycle block without apoptosis. Cisplatin allowed cell-cycle progression with progressive ATR and ATM-dependent, P53-independent apoptosis over subsequent cell-cycles. UV-irradiation of morula caused an ATR and ATM-dependent, P53-independent block of blastocyst formation while the block caused by cisplatin was ATR and ATM-dependent and at least partially P53-dependent. The results demonstrate complexity and maturation of the cellular responses of the embryo to defined genotoxic stressors and help to define the nature of embryopathy under these circumstances.

A genomic view of the sea urchin nervous system

The sequencing of the Strongylocentrotus purpuratus genome provides a unique opportunity to investigate the function and evolution of neural genes. The neurobiology of sea urchins is of particular interest because they have a close phylogenetic relationship with chordates, yet a distinctive pentaradiate body plan and unusual neural organization. Orthologues of transcription factors that regulate neurogenesis in other animals have been identified and several are expressed in neurogenic domains before gastrulation indicating that they may operate near the top of a conserved neural gene regulatory network. A family of genes encoding voltage-gated ion channels is present but, surprisingly, genes encoding gap junction proteins (connexins and pannexins) appear to be absent. Genes required for synapse formation and function have been identified and genes for synthesis and transport of neurotransmitters are present. There is a large family of G-protein-coupled receptors, including 874 rhodopsin-type receptors, 28 metabotropic glutamate-like receptors and a remarkably expanded group of 161 secretin receptor-like proteins. Absence of cannabinoid, lysophospholipid and melanocortin receptors indicates that this group may be unique to chordates. There are at least 37 putative G-protein-coupled peptide receptors and precursors for several neuropeptides and peptide hormones have been identified, including SALMFamides, NGFFFamide, a vasotocin-like peptide, glycoprotein hormones and insulin/insulin-like growth factors. Identification of a neurotrophin-like gene and Trk receptor in sea urchin indicates that this neural signaling system is not unique to chordates. Several hundred chemoreceptor genes have been predicted using several approaches, a number similar to that for other animals. Intriguingly, genes encoding homologues of rhodopsin, Pax6 and several other key mammalian retinal transcription factors are expressed in tube feet, suggesting tube feet function as photosensory organs. Analysis of the sea urchin genome presents a unique perspective on the evolutionary history of deuterostome nervous systems and reveals new approaches to investigate the development and neurobiology of sea urchins.

Stage dependent and androgen inductive expression of orphan receptor TR4 in rat testis

In this study, we investigated the expression of TR4 in different stages of seminiferous tubules and the relationship between TR4 and androgen in rat testis. We found that TR4 was stage-dependently expressed in rat seminiferous tubules, T withdrawal induced by high doses of testosterone undecanoate and ethane dimethane sulfonate inhibit TR4 expression in rat testis, and testosterone induced TR4 expression in co-cultured primary germ/Sertoli cells. Furthermore, we demonstrated that androgen receptor could enhance TR4-mediated transactivation activity in testis cells in the presence of testosterone. Together, these data indicate that the expression of TR4 in rat testis is stage dependent and androgen inductive, and suggest the important role of orphan receptor TR4 in spermatogenesis.

Targeted inactivation of testicular nuclear orphan receptor 4 delays and disrupts late meiotic prophase and subsequent meiotic divisions of spermatogenesis

Testicular orphan nuclear receptor 4 (TR4) is specifically and stage-dependently expressed in late-stage pachytene spermatocytes and round spermatids. In the developing mouse testis, the highest expression of TR4 can be detected at postnatal days 16 to 21 when the first wave of spermatogenesis progresses to late meiotic prophase. Using a knockout strategy to delete TR4 in mice, we found that sperm production in TR4(-/-) mice is reduced. The comparison of testes from developing TR4(+/+) and TR4(-/-) mice shows that spermatogenesis in TR4(-/-) mice is delayed. Analysis of the first wave of spermatogenesis shows that the delay can be due to delay and disruption of spermatogenesis at the end of late meiotic prophase and subsequent meiotic divisions. Seminiferous tubule staging shows that stages X to XII, where late meiotic prophase and meiotic divisions take place, are delayed and disrupted in TR4(-/-) mice. Histological examination of testis sections from TR4(-/-) mice shows degenerated primary spermatocytes and some necrotic tubules. Testis-specific gene analyses show that the expression of sperm 1 and cyclin A1, which are genes expressed at the end of meiotic prophase, was delayed and decreased in TR4(-/-) mouse testes. Taken together, results from TR4(+/+) and TR4(-/-) mice indicate that TR4 is essential for normal spermatogenesis in mice.

TR3 orphan nuclear receptor mediates apoptosis through up-regulating E2F1 in human prostate cancer LNCaP cells

Early studies suggested both TR3 orphan receptor (TR3) and apoptosis mediator E2F1 might play an important role in mediating prostate cancer cell apoptosis. Their linkage and relationship, however, remain unclear. Here we found that 12-O-tetradecanoylphorbol-13-acetate (TPA) could induce cell apoptosis via induction of TR3 and E2F1 expression in LNCaP prostate cancer cells. Addition of antisense E2F1 could partially rescue the TR3-mediated cell apoptosis, and transfection of the TR3 dominant-negative plasmid could block the TR3-induced E2F1 expression. These data suggest that TPA is able to induce LNCaP cell apoptosis via induction of TR3 resulting in the induction of E2F1. Promoter reporter assays show that TR3 can induce E2F1 expression via binding to the TR3 response element (TR3RE) in the E2F1 promoter -316 to -324 bp region. TR3 can bind specifically to this TR3RE with a Kd of 6.29 nm, and mutations of this E2F1-TR3RE can partially block the TR3-mediated E2F1 expression. Taken together, these data suggest that TPA is able to induce cell apoptosis via a TPA --> TR3 --> E2F1 --> apoptosis pathway in LNCaP cells. Further studies of how to modulate this pathway may allow us to better understand how to control the prostate cancer growth.

TR2 orphan receptor functions as negative modulator for androgen receptor in prostate cancer cells PC-3

BACKGROUND

Both androgen receptor (AR) and orphan receptor TR2 (TR2) belong to the steroid nuclear receptor superfamily and are expressed in prostate cancer tissue and cell lines. AR has been known to be involved in prostate proliferation and prostate cancer progression. AR binds to androgen response elements and regulates target gene expression via a mechanism involving coregulators. However, the function of TR2 in prostate and prostate cancer and the relationship between TR2 and AR in the prostate cancer is unclear.

METHODS

Transient transfection and CAT reporter gene assays were employed to assess AR-mediated transactivation. The expression level of prostate specific antigen (PSA) was measured by Northern blot analysis. The interaction between AR and TR2 was assessed by glutathione-S-transferase (GST) pull-down assay and mammalian two-hybrid system assay.

RESULTS

Orphan nuclear receptor TR2 suppressed androgen-mediated transactivation in prostate cancer PC-3 cells, and over-expression of TR2 suppressed PSA expression. The suppression of AR mediated transactivation by TR2 is not due to competition for the limited coregulator availability by these two receptors, but possibly through the interaction between TR2 and AR nuclear receptors.

CONCLUSIONS

TR2 may function as a negative modulator to suppress AR function in prostate cancer. Further studies on how to control TR2 function may result in the ability to modulate AR function in prostate cancer.