Characterization and evolution of two bacteriome‐inhabiting symbionts in cixiid planthoppers (Hemiptera: Fulgoromorpha: Pentastirini)

Like other plant sap‐sucking insects, planthoppers within the family Cixiidae (Insecta: Hemiptera: Fulgoromorpha) host a diversified microbiota. We report the identification and first molecular characterization of symbiotic bacteria in cixiid planthoppers (tribe: Pentastirini). Using universal eubacterial primers we first screened the eubacterial 16S rRNA sequences in Pentastiridius leporinus (Linnaeus) with PCR amplification, cloning, and restriction fragment analysis. We identified three main 16S rRNA sequences that corresponded to a Wolbachia bacterium, a plant pathogenic bacterium, and a novel gammaproteobacterial symbiont. A fourth bacterial species affiliated with ‘Candidatus Sulcia muelleri’ was detected in PCR assays using primers specific for the Bacteroidetes. Within females of two selected cixiid planthoppers, P. leporinus and Oliarus filicicola, fluorescence In situ hybridization analysis and transmission electron microscopy observations showed that ‘Ca. Sulcia muelleri’ and the novel gammaproteobacterial symbiont were housed in separate bacteriomes. Phylogenetic analysis revealed that both of these symbionts occurred in at least four insect genera within the tribe Pentastirini. ‘Candidatus Purcelliella pentastirinorum’ was proposed as the novel gammaproteobacterial symbiont.     

The prevalence of 'Candidatus Arsenophonus phytopathogenicus' infecting the planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) increase nonlinearly with the population abundance in sugar beet fields

The planthopper Pentastiridius leporinus (L.) (Hemiptera: Cixiidae) has been identified as the main vector of 'Candidatus Arsenophonus phytopathogenicus', a plant pathogenic bacterium associated to a sugar beet disease in eastern France called syndrome 'basses richesses'. In a 2-yr survey (2006-07), we quantified the abundance of P. leporinus populations migrating into 29 sugar beet fields in eastern France. Sticky traps posted in these fields were monitored on a twice-weekly (2006) or weekly (2007) basis. Subsets of the captured planthoppers were tested for the presence of Ca. A. phytopathogenicus through polymerase chain reaction (PCR). Our results showed that planthoppers colonized sugar beet fields in June and July of each year, following temporal patterns of migration that were fitted to logistic functions. The number of planthoppers migrating into sugar beet fields greatly varied among the fields and the years surveyed, averaging from a few (2-10) to over 400 planthoppers per trap. Interestingly, the prevalence of planthoppers infected by Ca. A. phytopathogenicus increased nonlinearly with the abundance of planthoppers captured on the traps. The proportion of infection for Ca. A. phytopathogenicus ranged from ?0.07-1 (total infection) in small (2-10 planthoppers per trap) and large (400 planthoppers per trap) populations, respectively. We hypothesize that the outbreaks of P. leporinus in sugar beet fields, and the consequent increased rates of planthoppers infected by the Ca. A. phytopathogenicus, are key factors leading to the emergence of the sugar beet disease in eastern France.     

Ethylene signalling is involved in regulation of phosphate starvation-induced gene expression and production of acid phosphatases and anthocyanin in Arabidopsis

? With the exception of root hair development, the role of the phytohormone ethylene is not clear in other aspects of plant responses to inorganic phosphate (Pi) starvation. ? The induction of AtPT2 was used as a marker to find novel signalling components involved in plant responses to Pi starvation. Using genetic and chemical approaches, we examined the role of ethylene in the regulation of plant responses to Pi starvation. ? hps2, an Arabidopsis mutant with enhanced sensitivity to Pi starvation, was identified and found to be a new allele of CTR1 that is a key negative regulator of ethylene responses. 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, increases plant sensitivity to Pi starvation, whereas the ethylene perception inhibitor Ag+ suppresses this response. The Pi starvation-induced gene expression and acid phosphatase activity are also enhanced in the hps2 mutant, but suppressed in the ethylene-insensitive mutant ein2-5. By contrast, we found that ethylene signalling plays a negative role in Pi starvation-induced anthocyanin production. ? These findings extend the roles of ethylene in the regulation of plant responses to Pi starvation and will help us to gain a better understanding of the molecular mechanism underlying these responses.     

TGF-β mediates early angiogenesis and latent fibrosis in an Emilin1-deficient mouse model of aortic valve disease

Aortic valve disease (AVD) is characterized by elastic fiber fragmentation (EFF), fibrosis and aberrant angiogenesis. Emilin1 is an elastin-binding glycoprotein that regulates elastogenesis and inhibits TGF-β signaling, but the role of Emilin1 in valve tissue is unknown. We tested the hypothesis that Emilin1 deficiency results in AVD, mediated by non-canonical (MAPK/phosphorylated Erk1 and Erk2) TGF-β dysregulation. Using histology, immunohistochemistry, electron microscopy, quantitative gene expression analysis, immunoblotting and echocardiography, we examined the effects of Emilin1 deficiency (Emilin1^−/−) in mouse aortic valve tissue. Emilin1 deficiency results in early postnatal cell-matrix defects in aortic valve tissue, including EFF, that progress to latent AVD and premature death. The Emilin1^−/− aortic valve displays early aberrant provisional angiogenesis and late neovascularization. In addition, Emilin1^−/− aortic valves are characterized by early valve interstitial cell activation and proliferation and late myofibroblast-like cell activation and fibrosis. Interestingly, canonical TGF-β signaling (phosphorylated Smad2 and Smad3) is upregulated constitutively from birth to senescence, whereas non-canonical TGF-β signaling (phosphorylated Erk1 and Erk2) progressively increases over time. Emilin1 deficiency recapitulates human fibrotic AVD, and advanced disease is mediated by non-canonical (MAPK/phosphorylated Erk1 and Erk2) TGF-β activation. The early manifestation of EFF and aberrant angiogenesis suggests that these processes are crucial intermediate factors involved in disease progression and therefore might provide new therapeutic targets for human AVD.KEY WORDS: Elastic fibers, Extracellular matrix, Aortic valve, Fibrosis, Angiogenesis     

Selective Augmentation of Stem Cell Populations in Structural Fat Grafts for Maxillofacial Surgery

Structural fat grafting utilizes the centrifugation of liposuction aspirates to create a graded density of adipose tissue. This study was performed to qualitatively investigate the effects of centrifugation on stem cells present in adipose tissue. Liposuction aspirates were obtained from healthy donors and either not centrifuged or centrifuged at 1,800 rpm for 3 minutes. The obtained fat volumes were divided into three layers and then analyzed. The results demonstrate that centrifugation induces a different distribution of stem cells in the three layers. The high-density layer displays the highest expression of mesenchymal stem cell and endothelial markers. The low-density layer exhibits an enrichment of multipotent stem cells. We conclude that appropriate centrifugation concentrates stem cells. This finding may influence the clinical practice of liposuction aspirate centrifugation and enhance graft uptake.     

Effects of a mutation that eliminates UDP glucose-pyrophosphorylase on the pathogenicity of Erwinia carotovora subsp. carotovora.

A nonpathogenic mutant of Erwinia carotovora obtained by Mu d1 mutagenesis was defective in the ability to utilize several carbon sources. The basis of the mutation was analyzed biochemically and shown to be a defect in the ability to form UDP glucose-pyrophosphorylase. The nonpathogenic phenotype of the mutant was caused by its sensitivity to galactose.     

Enhanced H Transport Capacity and ATP Hydrolysis Activity of the Tonoplast H-ATPase after NaCl Adaptation

Tonoplast enriched membrane vesicle fractions were isolated from unadapted and NaCl (428 millimolar) adapted tobacco cells (Nicotiana tabacum L. var Wisconsin 38). Polypeptides from the tonoplast enriched vesicle fractions were separated by SDS-PAGE and analyzed by Western blots using polyclonal antibodies to the 70 kilodalton subunit of the red beet tonoplast H⁺-ATPase. These antibodies cross-reacted exclusively to a tobacco polypeptide of an apparent molecular weight of 69 kilodaltons. The antibodies inhibited ATP-dependent, NO₃⁻ sensitive H⁺ transport into vesicles in tonoplast enriched membrane fractions from both unadapted and NaCl adapted cells. The relative H⁺ transport capacity per unit of 69 kilodalton subunit of the tonoplast ATPase of vesicles from NaCl adapted cells was fourfold greater than that observed for vesicles from unadapted cells. The increase in specific H⁺ transport capacity after adaptation was also observed for ATP hydrolysis.     

Intracellular compartmentation of ions in salt adapted tobacco cells

Na⁺ and Cl⁻ are the principal solutes utilized for osmotic adjustment in cells of Nicotiana tabacum L. var Wisconsin 38 (tobacco) adapted to NaCl, accumulating to levels of 472 and 386 millimolar, respectively, in cells adapted to 428 millimolar NaCl. X-ray microanalysis of unetched frozen-hydrated cells adapted to salt indicated that Na⁺ and Cl⁻ were compartmentalized in the vacuole, at concentrations of 780 and 624 millimolar, respectively, while cytoplasmic concentrations of the ions were maintained at 96 millimolar. The morphometric differences which existed between unadapted and salt adapted cells, (cytoplasmic volume of 22 and 45% of the cell, respectively), facilitated containment of the excited volume of the x-ray signal in the cytoplasm of the adapted cells. Confirmation of ion compartmentation in salt adapted cells was obtained based on kinetic analyses of ²²Na⁺ and ³⁶Cl⁻ efflux from cells in steady state. These data provide evidence that ion compartmentation is a component of salt adaptation of glycophyte cells.