Publications

4866

AbstractBackground:  “Candidatus Helicobacter heilmannii” induce chronic gastritis, which eventually leads to gastric B‐cell type mucosa‐associated lymphoid tissue (MALT) lymphoma. This study was performed using an animal model of infection with “Candidatus Helicobacter heilmannii” to elucidate how this chronic inflammation is induced or maintained.Materials and Methods:  BALB/c mice were infected with the “Candidatus Helicobacter heilmannii” isolate SH4. The animals were examined at 8, 26, 54, and 83 weeks after the infection. The stomach of the animals was resected and immunostained for peripheral lymph node addressin (PNAd) and mucosal addressin cell adhesion molecule 1 (MAdCAM‐1), “Candidatus Helicobacter heilmannii,” and CD45R/B220. An in vitro binding assay with L‐ and E‐selectin·IgM chimeric proteins was performed. Real‐time polymerase chain reaction was used to evaluate transcripts of N‐acetylglucosamine‐6‐O‐sulfotransferases (GlcNAc6STs), which direct the expression of the PNAd and MAdCAM‐1.Results:  Chronic gastritis developed in the infected animals, and its severity increased with the duration of the infection. B‐cell type MALT lymphoma developed in some animals at 54 and 83 weeks after infection. PNAd‐ and MAdCAM‐1‐expressing high endothelial venule (HEV)‐like vessels were induced in infected animals which developed chronic gastritis and MALT lymphoma. The number of HEV‐like vessels increased as chronic inflammation progressed. The induced HEV‐like vessels were bound by L‐ and E‐selectin·IgM chimeric protein. mRNA expressions of GlcNAc6ST‐1 and MAdCAM‐1 increased in the infected animals.Conclusions:  HEV‐like vessels expressing GlcNAc6ST‐1‐mediated L‐selectin ligand carbohydrate and MAdCAM‐1 may play a crucial role in the pathogenesis of “Candidatus Helicobacter heilmannii”‐induced chronic gastritis and MALT lymphoma.

ABSTRACT Mealybugs (Coccoidea: Pseudococcidae) are sap-sucking plant parasites that harbor bacterial endosymbionts within specialized organs. Previous studies have identified two subfamilies, Pseudococcinae and Phenacoccinae, within mealybugs and determined the primary endosymbionts (P-endosymbionts) of the Pseudococcinae to be Betaproteobacteria (“ Candidatus Tremblaya princeps”) containing Gammaproteobacteria secondary symbionts. Here, the P-endosymbionts of phenacoccine mealybugs are characterized based on 16S rRNA from the bacteria of 20 species of phenacoccine mealybugs and four outgroup Puto species (Coccoidea: Putoidae) and aligned to more than 100 published 16S rRNA sequences from symbiotic and free-living bacteria. Phylogenetic analyses recovered three separate lineages of bacteria from the Phenacoccinae, and these are considered to be the P-endosymbionts of their respective mealybug hosts, with those from (i) the mealybug genus Rastrococcus belonging to the Bacteroidetes , (ii) the subterranean mealybugs, tribe Rhizoecini, also within Bacteroidetes , in a clade sister to cockroach endosymbionts ( Blattabacterium ), and (iii) the remaining Phenacoccinae within the Betaproteobacteria , forming a well-supported sister group to “ Candidatus Tremblaya princeps.” Names are proposed for two strongly supported lineages: “ Candidatus Brownia rhizoecola” for P-endosymbionts of Rhizoecini and “ Candidatus Tremblaya phenacola” for P-endosymbionts of Phenacoccinae excluding Rastrococcus and Rhizoecini. Rates of nucleotide substitution among lineages of Tremblaya were inferred to be significantly faster than those of free-living Betaproteobacteria . Analyses also recovered a clade of Gammaproteobacteria , sister to the P-endosymbiont lineage of aphids (“ Candidatus Buchnera aphidicola”), containing the endosymbionts of Putoidae, the secondary endosymbionts of pseudococcine mealybugs, and the endosymbionts of several other insect groups.

Crotalaria spectabilis Roth. (Fabaceae), commonly known as showy rattlebox, is an herbaceous legume mainly used as a green manure crop to improve soil properties and as a source of durable fiber. However, the plant is toxic to mammals and birds because of the presence of pyrrolidizine alkaloids. A native of India and the Malay Peninsula, the species has been introduced into other areas such as the United States and Pacific Islands where the plant is an invader of cultivated lands. Fasciated rattlebox plants were sighted in fields in New Delhi in February 2010, with approximately 99% of the examined plants symptomatic. Symptoms included flattening of stems in a descending gradient of severity from the apex to the base of each affected branch. Shoots showed longitudinal undulations bearing highly reduced leaves and uneven distribution of flowers and fruits. To identify the causal agent, 10 symptomatic plants and 8 asymptomatic plants (latter sampled from a field approximately 1.5 km away) were collected for nucleic acid analysis. Total genomic DNA was extracted from flattened stems as well as the roots of symptomatic plants, and from the same tissues of asymptomatic plants, and subjected to nested-PCR using phytoplasma 16S ribosomal DNA universal primer pair P1/P7, followed by R16F2/R2 (4). A known aster yellows-infected Catharanthus roseus plant was used as a control sample. Results depicted a characteristic phytoplasma amplicon of 1.25 kb in all samples from symptomatic plants and the control plant. No amplification was observed from asymptomatic plants. To obtain a full-length sequence, a representative amplicon was purified with the QIAquick gel extraction kit (QIAGEN, Valencia, CA), cloned into pGEM-T Easy vector (Promega, Madison, WI), and sequenced. Comparison of the 1,243-bp sequence (Genbank Accession No. HM137557) using BLAST analysis of the NCBI database showed 99% homology with sequences of members of 16SrI group phytoplasmas, i.e., ‘Candidatus Phytoplasma asteris’ such as Japanese spurge yellows (AB551736.1), Mulberry yellow dwarf (GQ249410.1), and Bamboo witches'-broom (FJ853161.1) phytoplasmas. The profiles of in vitro restriction fragment length polymorphism (RFLP) analysis obtained by digestion of the nested-PCR products with HhaI, KpnI, and AluI were similar to those of in silico RFLP analyses and coincided with the pattern of the 16SrI-B subgroup. Phylogenetic analysis of phytoplasma 16S rDNA sequences based on the maximum likelihood method using MEGA Version 4.1 also placed the Crotalaria fasciation (CF) phytoplasma within the 16SrI-B cluster. In India, C. tetragona plants infected with 16SrI phytoplasma (FJ185141) causing witches'-broom symptoms (1) showed 98% similarity with the CF phytoplasma. However, the results support previous molecular investigations associating 16SrI phytoplasma with fasciation of herbaceous plants, including Lilium spp. (2) and Asparagus officinalis (3). To our knowledge, C. spectabilis represents a new host that can be fasciated as a result of phytoplasma infection. Because of the weedy nature of C. spectabilis, this host could facilitate spread of the phytoplasma. References: (1) P. Baiswar et al. Plant Pathol. 19:17, 2009. (2) A. Bertaccini et al. FEMS Microbiol. Lett. 249:79, 2005. (3) J. Franova and K. Petrzik. J. Phytopathol. 158:317, 2010.K. (4) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996.