Dataset for de novo transcriptome assembly of the African bullfrog Pyxicephalus adspersus

In this article, we report the first de novo transcriptome assembly of the African bullfrog Pyxicephalus adspersus. In this data, 75,320,390 raw reads were acquired from African bullfrog mRNA using Illumina paired-end sequencing platform. De novo assembly resulted in a total of 136,958 unigenes. In the obtained unigenes, 30,039 open reading frames (ORFs) were detected. This dataset provides basic information for molecular level analysis of this species, which undergoes a state of dormancy under dry conditions at ordinary temperatures called estivation

Animal infection models using non‐mammals

The use of non‐human animal models for infection experiments is important for investigating the infectious processes of human pathogenic bacteria at the molecular level. Mammals, such as mice and rabbits, are also utilized as animal infection models, but large numbers of animals are needed for these experiments, which is costly, and fraught with ethical issues. Various non‐mammalian animal infection models have been used to investigate the molecular mechanisms of various human pathogenic bacteria, including Staphylococcus aureus, Streptococcus pyogenes, and Pseudomonas aeruginosa. This review discusses the desirable characteristics of non‐mammalian infection models and describes recent non‐mammalian infection models that utilize Caenorhabditis elegans, silkworm, fruit fly, zebrafish, two‐spotted cricket, hornworm, and waxworm

Staphylococcus aureus aggregation in the plasma fraction of silkworm hemolymph

Staphylococcus aureus formed bacterial aggregates in the plasma fraction of the hemolymph of silkworm, the larva of Bombyx mori, in a growth-dependent manner. The addition of arabinose or galactose inhibited the formation of S. aureus aggregates in the silkworm plasma. Formation of the bacterial aggregates depended on S. aureus genes required for the synthesis of bacterial surface polysaccharides-ypfP and ltaA, which are involved in lipoteichoic acid synthesis, and the tagO gene, which is involved in wall teichoic acid synthesis. These findings suggest that S. aureus forms bacterial aggregates in the silkworm plasma via bacterial surface teichoic acids

ATP and its metabolite adenosine cooperatively upregulate the antigen-presenting molecules on dendritic cells leading to IFN-gamma production by T cells

Dendritic cells (DCs) present foreign antigens to T cells via the major histocompatibility complex (MHC), thereby inducing acquired immune responses. ATP accumulates at sites of inflammation or in tumor tissues, which triggers local inflammatory responses. However, it remains to be clarified how ATP modulates the functions of DCs. In this study, we investigated the effects of extracellular ATP on mouse bone marrow- derived dendritic cells (BMDCs) as well as the potential for subsequent T cell activation. We found that high concentrations of ATP (1 mM) upregulated the cell surface expression levels of MHC-I, MHC-II, and co-stimulatory molecules CD80 and CD86 but not those of co-inhibitory molecules PD-L1 and PD-L2 in BMDCs. Increased surface expression of MHC-I, MHC-II, CD80, and CD86 was inhibited by a pan-P2 receptor antagonist. In addition, the upregulation of MHC-I and MHC-II expression was inhibited by an adenosine P1 receptor antagonist and by inhibitors of CD39 and CD73, which metabolize ATP to adenosine. These results suggest that adenosine is required for the ATP-induced upregulation of MHC-I and MHC-II. In the mixed leukocyte reaction assay, ATP-stimulated BMDCs activated CD4 and CD8T cells and induced interferon-gamma (IFN-gamma) production by these T cells. Collectively, these results suggest that high concentrations of extracellular ATP upregulate the expression of antigenpresenting and co-stimulatory molecules but not that of coinhibitory molecules in BMDCs. Cooperative stimulation of ATP and its metabolite adenosine was required for the upregulation of MHC-I and MHC-II. These ATP-stimulated BMDCs induced the activation of IFN-gamma-producing T cells upon antigen presentation

A Novel Gene, fudoh, in the SCCmec Region Suppresses the Colony Spreading Ability and Virulence of Staphylococcus aureus

Staphylococcus aureus colonies can spread on soft agar plates. We compared colony spreading of clinically isolated methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). All MSSA strains showed colony spreading, but most MRSA strains (73%) carrying SCCmec type-II showed little colony spreading. Deletion of the entire SCCmec type-II region from these MRSA strains restored colony spreading. Introduction of a novel gene, fudoh, carried by SCCmec type-II into Newman strain suppressed colony spreading. MRSA strains with high spreading ability (27%) had no fudoh or a point-mutated fudoh that did not suppress colony spreading. The fudoh-transformed Newman strain had decreased exotoxin production and attenuated virulence in mice. Most community-acquired MRSA strains carried SCCmec type-IV, which does not include fudoh, and showed high colony spreading ability. These findings suggest that fudoh in the SCCmec type-II region suppresses colony spreading and exotoxin production, and is involved in S. aureus pathogenesis

Tree of motility – A proposed history of motility systems in the tree of life

Motility often plays a decisive role in the survival of species. Five systems of motility have been studied in depth: those propelled by bacterial flagella, eukaryotic actin polymerization and the eukaryotic motor proteins myosin, kinesin and dynein. However, many organisms exhibit surprisingly diverse motilities, and advances in genomics, molecular biology and imaging have showed that those motilities have inherently independent mechanisms. This makes defining the breadth of motility nontrivial, because novel motilities may be driven by unknown mechanisms. Here, we classify the known motilities based on the unique classes of movement-producing protein architectures. Based on this criterion, the current total of independent motility systems stands at 18 types. In this perspective, we discuss these modes of motility relative to the latest phylogenetic Tree of Life and propose a history of motility. During the ~4 billion years since the emergence of life, motility arose in Bacteria with flagella and pili, and in Archaea with archaella. Newer modes of motility became possible in Eukarya with changes to the cell envelope. Presence or absence of a peptidoglycan layer, the acquisition of robust membrane dynamics, the enlargement of cells and environmental opportunities likely provided the context for the (co)evolution of novel types of motility

Transcription and Translation Products of the Cytolysin Gene psm-mec on the Mobile Genetic Element SCCmec Regulate Staphylococcus aureus Virulence

The F region downstream of the mecI gene in the SCCmec element in hospital-associated methicillin-resistant Staphylococcus aureus (HA-MRSA) contains two bidirectionally overlapping open reading frames (ORFs), the fudoh ORF and the psm-mec ORF. The psm-mec ORF encodes a cytolysin, phenol-soluble modulin (PSM)-mec. Transformation of the F region into the Newman strain, which is a methicillin-sensitive S. aureus (MSSA) strain, or into the MW2 (USA400) and FRP3757 (USA300) strains, which are community-acquired MRSA (CA-MRSA) strains that lack the F region, attenuated their virulence in a mouse systemic infection model. Introducing the F region to these strains suppressed colony-spreading activity and PSMα production, and promoted biofilm formation. By producing mutations into the psm-mec ORF, we revealed that (i) both the transcription and translation products of the psm-mec ORF suppressed colony-spreading activity and promoted biofilm formation; and (ii) the transcription product of the psm-mec ORF, but not its translation product, decreased PSMα production. These findings suggest that both the psm-mec transcript, acting as a regulatory RNA, and the PSM-mec protein encoded by the gene on the mobile genetic element SCCmec regulate the virulence of Staphylococcus aureus

Knockout of adenylosuccinate synthase purA increases susceptibility to colistin in Escherichia coli

Colistin is a cationic cyclic antimicrobial peptide used as a last resort against multidrug-resistant gram-negative bacteria. To understand the factors involved in colistin susceptibility, we screened colistin-sensitive mutants from an E. coli gene-knockout library (Keio collection). The knockout of purA, whose product catalyzes the synthesis of adenylosuccinate from IMP in the de novo purine synthesis pathway, resulted in increased sensitivity to colistin. Adenylosuccinate is subsequently converted to AMP, which is phosphorylated to produce ADP, a substrate for ATP synthesis. The amount of ATP was lower in the purA-knockout mutant than that in the wild-type strain. ATP synthesis is coupled with proton transfer, and it contributes to the membrane potential. Using the membrane potential probe, 3,3′-diethyloxacarbocyanine iodide [DiOC2(3)], we found that the membrane was hyperpolarized in the purA-knockout mutant compared to that in the wild-type strain. Treatment with the proton uncoupler, carbonyl cyanide m-chlorophenyl hydrazone (CCCP), abolished the hyperpolarization and colistin sensitivity in the mutant. The purA-knockout mutant exhibited increased sensitivity to aminoglycosides, kanamycin, and gentamicin; their uptake requires a membrane potential. Therefore, the knockout of purA, an adenylosuccinate synthase, decreases ATP synthesis concurrently with membrane hyperpolarization, resulting in increased sensitivity to colistin