Clonal isolation of chlamydia-infected cells using flow cytometry

Virulence Protein Pgp3 Is Insufficient To Mediate Plasmid-Dependent Infectivity of Chlamydia trachomatis

Chlamydia trachomatis is the most common cause of infectious blindness and sexually transmitted bacterial infection globally. C. trachomatis contains a conserved chlamydial plasmid with eight coding sequences. Plasmid-cured Chlamydia strains are attenuated and display reduced infectivity in cell culture and in vivo genital infection of female mice. Mutants that do not express the plasmid-encoded proteins Pgp3, a secreted protein with unknown function, or Pgp4, a putative regulator of pgp3 and other chromosomal loci, display an infectivity defect similar to plasmid-deficient strains. Our objective was to determine the combined and individual contributions of Pgp3 and Pgp4 to this phenotype. Deletion of pgp3 and pgp4 resulted in an infectivity defect detected by competition assay in cell culture and in mice. The pgp3 locus was placed under the control of an anhydrotetracycline-inducible promoter to examine the individual contributions of Pgp3 and Pgp4 to infectivity. Expression of pgp3 was induced 100- to 1,000-fold after anhydrotetracycline administration, regardless of the presence or absence of pgp4. However, secreted Pgp3 was not detected when pgp4 was deleted, confirming a role for Pgp4 in Pgp3 secretion. We discovered that expression of pgp3 or pgp4 alone was insufficient to restore normal infectivity, which required expression of both Pgp3 and Pgp4. These results suggest Pgp3 and Pgp4 are both required for infectivity during C. trachomatis infection. Future studies are required to determine the mechanism by which Pgp3 and Pgp4 influence chlamydial infectivity as well as the potential roles of Pgp4-regulated loci.

Comparison of the diversity and structure of the rhizosphere microbial community between the straight and twisted trunk types of Pinus yunnanensis

Background

Pinus yunnanensis is a major silvicultural species in Southwest China. Currently, large areas of twisted-trunk Pinus yunnanensis stands severely restrict its productivity. Different categories of rhizosphere microbes evolve alongside plants and environments and play an important role in the growth and ecological fitness of their host plant. However, the diversity and structure of the rhizosphere microbial communities between P. yunnanensis with two different trunk types-straight and twisted-remain unclear.

Methods

We collected the rhizosphere soil of 5 trees with the straight and 5 trees with the twisted trunk type in each of three sites in Yunnan province. We assessed and compared the diversity and structure of the rhizosphere microbial communities between P. yunnanensis with two different trunk types by Illumina sequencing of 16S rRNA genes and internal transcribed spacer (ITS) regions.

Results

The available phosphorus in soil differed significantly between P. yunnanensis with straight and twisted trunks. Available potassium had a significant effect on fungi. Chloroflexi dominated the rhizosphere soils of the straight trunk type, while Proteobacteria was predominant in the rhizosphere soils of the twisted trunk type. Trunk types significantly explained 6.79% of the variance in bacterial communities.

Conclusion

This study revealed the composition and diversity of bacterial and fungal groups in the rhizosphere soil of P. yunnanensis with straight and twisted trunk types, providing proper microbial information for different plant phenotypes.

Optimization of fermentation for γ-aminobutyric acid (GABA) production by yeast Kluyveromyces marxianus C21 in okara (soybean residue)

γ-Aminobutyric acid (GABA) is a non-protein amino acid with a variety of physiological functions. Recently, yeast Kluyveromyces marxianus strains involved in the catabolism and anabolism of GABA can be used as a microbial platform for GABA production. Okara, rich in nutrients, can be used as a low-cost fermentation substrate for the production of functional materials. This study first proved the advantages of the okara medium to produce GABA by K. marxianus C21 when L-glutamate (L-Glu) or monosodium glutamate (MSG) is the substrate. The highest production of GABA was obtained with 4.31 g/L at optimization condition of culture temperature 35 °C, fermentation time 60 h, and initial pH 4.0. Furthermore, adding peptone significantly increased the GABA production while glucose and vitamin B6 had no positive impact on GABA production. This research provided a powerful new strategy of GABA production by K. marxianus C21 fermentation and is expected to be widely utilized in the functional foods industry to increase GABA content for consumers as a daily supplement as suggested.

The Impacts of Dietary Fermented Mao-tai Lees on Growth Performance, Plasma Metabolites, and Intestinal Microbiota and Metabolites of Weaned Piglets

This study investigated the effects of dietary supplementation with fermented Mao-tai lees (FML) on growth performance, plasma metabolites, and intestinal microbiota and metabolites of weaned piglets. A total of 128 Duroc×Landrace×Yorkshire piglets (28-days old) were randomly assigned to one of four groups, feeding a basal diet (control group), a basal diet supplemented with 2, 4 or 6% FML, respectively, for 42days. The results showed that dietary 4% FML supplementation had higher (p<0.05) average daily gain (ADG) and plasma triglyceride concentration during days 1–14 of the trial than the other FML supplemented groups. In addition, dietary 2 and 4% FML supplementation increased (p<0.05) the ADG during days 15–28 of the trial and plasma total protein concentration on day 42 of the trial compared with the 6% FML supplement. The plasma concentrations of arginine, ethanolamine, histidine, isoleucine, lysine, methionine, proline, taurine, threonine, and tyrosine were increased (p<0.05) in the 4% FML group compared with the other three groups on day 14 of the trial. Dietary supplementation with 2–6% FML decreased (p<0.05) the plasma urea nitrogen concentration on day 14 of the trial and the abundance of Escherichia coli in the colon, and dietary 2 and 4% FML supplementation decreased (p<0.05) the abundance of sulfate-reducing bacteria compared with the control group. In the intestinal contents, a higher concentration of FML (6%) supplementation decreased (p<0.05) the colonic acetate concentration compared with the control and 2% FML groups, while 4% FML supplementation increased (p<0.05) the colonic cadaverine concentration compared with the other three groups. In conclusion, dietary 4% FML supplementation might contribute to the increased amino acids metabolism without affecting the growth performance of weaned piglets. Moreover, dietary 2 and 4% FML supplementation were also beneficial to intestinal health via decreasing the abundances of specific pathogens and increasing the concentrations of microbial metabolites in the gut, which provides the theoretical basis and data support for the application of FML in pigs.

Mycoplasma decontamination in Chlamydia trachomatis culture: a curative approach

Mycoplasma contamination of cell culture represents a serious problem in research and decontamination from cell-propagated obligate intracellular bacteria has proven challenging. Here, we presented an optimized protocol to remove Mycoplasma from contaminated Chlamydia trachomatis culture. A stepwise procedure of Mycoplasma removal entails (i) incubation in nonionic detergent containing solution, and (ii) separation of viable chlamydial organisms by fluorescence-activated cell sorting (FACS), followed by subcloning using a focus-forming assay. We also adapted a polymerase chain reaction (PCR) assay using paired universal and Mycoplasma-specific primers, which are distinguishable from the C. trachomatis counterparts, in combination with Sanger sequencing to determine the presence of mycoplasmas' 16S rRNA genes. These integrated approaches allow for full removal of Mycoplasma, as verified by the improved PCR assay, without compromising the capacity of viable C. trachomatis to adapt to new infection in epithelial cells. Some pitfalls during the Mycoplasma decontamination process are discussed.

Neuroprotective and Anti-Amyloid β Effect and Main Chemical Profiles of White Tea: Comparison Against Green, Oolong and Black Tea

White tea (WT) is one of six tea types originally derived from Fujian Province, China. White tea is known for its health-promoting properties. However, the neuroprotective and anti-aggregatory properties of WT against the hallmark toxic Alzheimer's protein, Aβ have not been investigated. In this study, WT, green tea (GT), oolong tea (OT) and black tea (BT) were manufactured using tea leaves from the cultivar Camellia sinensis (Jin Guanyin). The protective effects of these tea extracts were then studied under oxidative stress conditions via t-bhp and H₂O₂ exposure, in addition to Aβ treatment using a PC-12 cell model. Each tea type failed to rescue PC-12 cells from either t-bhp or H₂O₂-mediated toxicity, however each extract exerted significant protection against Aβ-evoked neurotoxicity. Results of the Thioflavin T Kinetic (ThT) and TEM assay showed that Aβ aggregate formation was inhibited by each tea type. Additionally, TEM also supported the different anti-aggregatory effect of WT by modifying Aβ into an amorphous and punctate aggregate morphology. Higher accumulated precedent or potential neuroprotective compounds in WT, including ECG''3Me, 8-C-ascorbyl-EGCG, GABA and Gln, in addition to flavonol or flavone glycosides detected by using UPLC-QTOF-MS and UPLC-QqQ-MS, may contribute to a favourable anti-aggregative and neuroprotective effect of WT against Aβ.

Engineering of obligate intracellular bacteria: progress, challenges and paradigms

It is estimated that approximately one billion people are at risk of infection with obligate intracellular bacteria, but little is known about the underlying mechanisms that govern their life cycles. The difficulty in studying Chlamydia spp., Coxiella spp., Rickettsia spp., Anaplasma spp., Ehrlichia spp. and Orientia spp. is, in part, due to their genetic intractability. Recently, genetic tools have been developed; however, optimizing the genomic manipulation of obligate intracellular bacteria remains challenging. In this Review, we describe the progress in, as well as the constraints that hinder, the systematic development of a genetic toolbox for obligate intracellular bacteria. We highlight how the use of genetically manipulated pathogens has facilitated a better understanding of microbial pathogenesis and immunity, and how the engineering of obligate intracellular bacteria could enable the discovery of novel signalling circuits in host-pathogen interactions.

Emancipating Chlamydia: Advances in the Genetic Manipulation of a Recalcitrant Intracellular Pathogen

Chlamydia species infect millions of individuals worldwide and are important etiological agents of sexually transmitted disease, infertility, and blinding trachoma. Historically, the genetic intractability of this intracellular pathogen has hindered the molecular dissection of virulence factors contributing to its pathogenesis. The obligate intracellular life cycle of Chlamydia and restrictions on the use of antibiotics as selectable markers have impeded the development of molecular tools to genetically manipulate these pathogens. However, recent developments in the field have resulted in significant gains in our ability to alter the genome of Chlamydia, which will expedite the elucidation of virulence mechanisms. In this review, we discuss the challenges affecting the development of molecular genetic tools for Chlamydia and the work that laid the foundation for recent advancements in the genetic analysis of this recalcitrant pathogen.

Fluorescent labeling reliably identifies Chlamydia trachomatis in living human endometrial cells and rapidly and accurately quantifies chlamydial inclusion forming units

Chlamydia replication requires host lipid acquisition, allowing flow cytometry to identify Chlamydia-infected cells that accumulated fluorescent Golgi-specific lipid. Herein, we describe modifications to currently available methods that allow precise differentiation between uninfected and Chlamydia trachomatis-infected human endometrial cells and rapidly and accurately quantify chlamydial inclusion forming units.

Discovering and differentiating new and emerging clonal populations of Chlamydia trachomatis with a novel shotgun cell culture harvest assay

This assay, coupled with ompA and 16S rRNA sequencing, characterized clonal populations of C. trachomatis.

Chlamydia trachomatis is the leading cause of preventable blindness and bacterial sexually transmitted diseases worldwide. Plaque assays have been used to clonally segregate laboratory-adapted C. trachomatis strains from mixed infections, but no assays have been reported to segregate clones from recent clinical samples. We developed a novel shotgun cell culture harvest assay for this purpose because we found that recent clinical samples do not form plaques. Clones were strain-typed by using outer membrane protein A and 16S rRNA sequences. Surprisingly, ocular trachoma reference strain A/SA-1 contained clones of Chlamydophila abortus. C. abortus primarily infects ruminants and pigs and has never been identified in populations where trachoma is endemic. Three clonal variants of reference strain Ba/Apache-2 were also identified. Our findings reflect the importance of clonal isolation in identifying constituents of mixed infections containing new or emerging strains and of viable clones for research to more fully understand the dynamics of in vivo strain-mixing, evolution, and disease pathogenesis.

Herpes simplex virus co-infection-induced Chlamydia trachomatis persistence is not mediated by any known persistence inducer or anti-chlamydial pathway

Several inducers of chlamydial persistence have been described, including interferon-gamma (IFN-gamma), IFN-alpha, IFN-beta, and tumour necrosis factor-alpha (TNF-alpha) exposure, and iron, amino acid or glucose deprivation. A tissue-culture model of Chlamydia trachomatis/herpes simplex virus type-2 (HSV-2) co-infection indicates that viral co-infection stimulates the formation of persistent chlamydiae. This study was designed to ascertain whether co-infection-induced persistence is mediated by a previously characterized mechanism. Luminex assays indicate that IFN-gamma, IFN-alpha, and TNF-alpha are not released from co-infected cells. Semiquantitative RT-PCR studies demonstrate that IFN-beta, IFN-gamma, indoleamine 2,3-dioxygenase, lymphotoxin-alpha and inducible nitric oxide synthase are not expressed during co-infection. These data indicate that viral-induced persistence is not stimulated by any persistence-associated cytokine. Supplementation of co-infected cells with excess amino acids, iron-saturated holotransferrin, glucose or a combination of amino acids and iron does not restore chlamydial infectivity, demonstrating that HSV-2-induced persistence is not mediated by depletion of these nutrients. Finally, inclusions within co-infected cells continue to enlarge and incorporate C(6)-NBD-ceramide, indicating that HSV-2 co-infection does not inhibit vesicular transport to the developing inclusion. Collectively these data demonstrate that co-infection-induced persistence is not mediated by any currently characterized persistence inducer or anti-chlamydial pathway. Previous studies indicate that HSV-2 attachment and/or entry into the host cell is sufficient for stimulating chlamydial persistence, suggesting that viral attachment and/or entry may trigger a novel host pathway which restricts chlamydial development.