Palm lethal decline phytoplasmas are an important group of plant pathogens that cause death in a variety of palm species throughout the Caribbean basin and the southeastern United States. The ...16SrIV-D phytoplasma was introduced to the state of Florida, United States; it has since caused severe economic losses to the green industries of Florida and is threating natural ecosystems because of its ability to infect the native palm
. In this study, the genetic variability of the 16SrIV-D phytoplasma was assessed over a 10-year period to determine if multiple introductions had occurred or if natural mutations were occurring. Furthermore, the genetic variability of the palm lethal decline phytoplasma group (16SrIV) was assessed with a multiple locus analysis using the 16S ribosomal RNA gene, the 16S-23S intergenic spacer region, and
and
genes. Overall, no variability of the 16SrIV-D phytoplasma was documented in Florida over a 10-year period. The multilocus analysis showed support for three distinct species of the phytoplasma in the Caribbean basin that infect palms and further support that the 16SrIV-C from Tanzania is not closely related. Furthermore, 16SrIV-B and 16SrIV-D were found to be the same phytoplasma based on 100% identity between the two based on intergenic spacer region,
, and
analysis. This study represents the first robust, multilocus analysis of palm-infecting phytoplasmas from the Caribbean and sheds light on the phylogeny and evolution of the group.
Rapamycin treatment has positive and negative effects on progression of type 2 diabetes (T2D) in a recombinant inbred polygenic mouse model, male NONcNZO10/LtJ (NcZ10). Here, we show that combination ...treatment with metformin ameliorates negative effects of rapamycin while maintaining its benefits. From 12 to 30 weeks of age, NcZ10 males were fed a control diet or diets supplemented with rapamycin, metformin, or a combination of both. Rapamycin alone reduced weight gain, adiposity, HOMA‐IR, and inflammation, and prevented hyperinsulinemia and pre‐steatotic hepatic lipidosis, but exacerbated hyperglycemia, hypertriglyceridemia, and pancreatic islet degranulation. Metformin alone reduced hyperinsulinemia and circulating c‐reactive protein, but exacerbated nephropathy. Combination treatment retained the benefits of both while preventing many of the deleterious effects. Importantly, the combination treatment reversed effects of rapamycin on markers of hepatic insulin resistance and normalized systemic insulin sensitivity in this inherently insulin‐resistant model. In adipose tissue, rapamycin attenuated the expression of genes associated with adipose tissue expansion (Mest, Gpam), inflammation (Itgam, Itgax, Hmox1, Lbp), and cell senescence (Serpine1). In liver, the addition of metformin counteracted rapamycin‐induced alterations of G6pc, Ppara, and Ldlr expressions that promote hyperglycemia and hypertriglyceridemia. Both rapamycin and metformin treatment reduced hepatic Fasn expression, potentially preventing lipidosis. These results delineate a state of “insulin signaling restriction” that withdraws endocrine support for further adipogenesis, progression of the metabolic syndrome, and the development of its comorbidities. Our results are relevant for the treatment of T2D, the optimization of current rapamycin‐based treatments for posttransplant rejection and various cancers, and for the development of treatments for healthy aging.
Rapamycin and metformin combination treatment in a mouse model of type 2 diabetes, NONcNZO10/LtJ males, prevents hyperinsulinemia, normalizes insulin sensitivity, and reduces pathological complications of diabetes. When combined, each compound prevents the negative side effects of the other. These results are relevant for the treatment of diabetes, the optimization of current rapamycin‐based treatments, and the development of treatments for healthy aging.
This study addressed the taxonomic position and group classification of a phytoplasma responsible for virescence and phyllody symptoms in naturally diseased Madagascar periwinkle plants in western ...Malaysia. Unique regions in the 16S rRNA gene from the Malaysian periwinkle virescence (MaPV) phytoplasma distinguished the phytoplasma from all previously described ‘Candidatus Phytoplasma’ species. Pairwise sequence similarity scores, calculated through alignment of full-length 16S rRNA gene sequences, revealed that the MaPV phytoplasma 16S rRNA gene shared 96.5 % or less sequence similarity with that of previously described ‘Ca. Phytoplasma’ species, justifying the recognition of the MaPV phytoplasma as a reference strain of a novel taxon, ‘Candidatus Phytoplasma malaysianum’. The 16S rRNA gene F2nR2 fragment from the MaPV phytoplasma exhibited a distinct restriction fragment length polymorphism (RFLP) profile and the pattern similarity coefficient values were lower than 0.85 with representative phytoplasmas classified in any of the 31 previously delineated 16Sr groups; therefore, the MaPV phytoplasma was designated a member of a new 16Sr group, 16SrXXXII. Phytoplasmas affiliated with this novel taxon and the new group included diverse strains infecting periwinkle, coconut palm and oil palm in Malaysia. Three phytoplasmas were characterized as representatives of three distinct subgroups, 16SrXXXII-A, 16SrXXXII-B and 16SrXXXII-C, respectively.
Mexican periwinkle virescence (MPV) phytoplasma was originally discovered in diseased plants of Madagascar periwinkle (Catharanthus roseus) in Yucatán, Mexico. On the basis of results from RFLP ...analysis of PCR-amplified 16S rRNA gene sequences, strain MPV was previously classified as the first known member of phytoplasma group 16SrXIII, and a new subgroup (16SrXIII-A) was established to accommodate MPV phytoplasma. Phylogenetic analysis of 16S rRNA gene sequences indicated that strain MPV represents a lineage distinct from previously described 'CandidatusPhytoplasma' species. Nucleotide sequence alignments revealed that strain MPV shared less than 97.5 % 16S rRNA gene sequence similarity with all previously described 'Ca.Phytoplasma' species. Based on unique properties of the DNA, we propose recognition of Mexican periwinkle virescence phytoplasma strain MPV as representative of a novel taxon, 'CandidatusPhytoplasma hispanicum'.
Landscape-grown foxtail palm (Wodyetia bifurcata A. K. Irvine) trees displaying symptoms of severe foliar chlorosis, stunting, general decline and mortality reminiscent of coconut yellow decline ...disease were observed in Bangi, Malaysia, during 2012. DNA samples from foliage tissues of 15 symptomatic palms were analysed by employing a nested PCR assay primed by phytoplasma universal ribosomal RNA operon primer pairs, P1/P7 followed by R16F2n/R2. The assay yielded amplicons of a single band of 1.25 kb from DNA samples of 11 symptomatic palms. Results from cloning and sequence analysis of the PCR-amplified 16S rRNA gene segments revealed that, in three palms, three mutually distinct phytoplasmas comprising strains related to 'Candidatus Phytoplasma asteris' and 'Candidatus Phytoplasma cynodontis', as well as a novel phytoplasma, were present as triple infections. The 16S rRNA gene sequence derived from the novel phytoplasma shared less than 96 % nucleotide sequence identity with that of each previously describedspecies of the provisional genus 'Ca. Phytoplasma', justifying its recognition as the reference strain of a new taxon, 'Candidatus Phytoplasma wodyetiae'. Virtual RFLP profiles of the R16F2n/R2 portion of the 16S rRNA gene and the pattern similarity coefficient value (0.74) supported the delineation of 'Ca. Phytoplasma wodyetiae' as the sole representative subgroup A member of a new phytoplasma ribosomal group, 16SrXXXVI.
In this study, the taxonomic position and group classification of the phytoplasma associated with a lethal yellowing-type disease (LYD) of coconut (Cocos nucifera L.) in Mozambique were addressed. ...Pairwise similarity values based on alignment of nearly full-length 16S rRNA gene sequences (1530 bp) revealed that the Mozambique coconut phytoplasma (LYDM) shared 100 % identity with a comparable sequence derived from a phytoplasma strain (LDN) responsible for Awka wilt disease of coconut in Nigeria, and shared 99.0–99.6 % identity with 16S rRNA gene sequences from strains associated with Cape St Paul wilt (CSPW) disease of coconut in Ghana and Côte d’Ivoire. Similarity scores further determined that the 16S rRNA gene of the LYDM phytoplasma shared <97.5 % sequence identity with all previously described members of ‘Candidatus Phytoplasma’. The presence of unique regions in the 16S rRNA gene sequence distinguished the LYDM phytoplasma from all currently described members of ‘Candidatus Phytoplasma’, justifying its recognition as the reference strain of a novel taxon, ‘Candidatus Phytoplasma palmicola’. Virtual RFLP profiles of the F2n/R2 portion (1251 bp) of the 16S rRNA gene and pattern similarity coefficients delineated coconut LYDM phytoplasma strains from Mozambique as novel members of established group 16SrXXII, subgroup A (16SrXXII-A). Similarity coefficients of 0.97 were obtained for comparisons between subgroup 16SrXXII-A strains and CSPW phytoplasmas from Ghana and Côte d’Ivoire. On this basis, the CSPW phytoplasma strains were designated members of a novel subgroup, 16SrXXII-B.
Peroxyacetyl nitrate (PAN) is an important chemical species in the troposphere as it aids the long-range transport of NOx and subsequent formation of O3 in relatively clean remote regions. Over the ...past few decades observations from aircraft campaigns and surface sites have been used to better understand the regional distribution of PAN. However, recent measurements made by satellites allow for a global assessment of PAN in the upper troposphere–lower stratosphere (UTLS). In this study, we investigate global PAN distributions from two independent retrieval methodologies, based on measurements from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument, on board Envisat from the Institute of Meteorology and Climate Research (IMK), Karlsruhe Institute of Technology, and the Department of Physics and Astronomy, University of Leicester (UoL). Retrieving PAN from MIPAS is challenging due to the weak signal in the measurements and contamination from other species. Therefore, we compare the two MIPAS datasets with observations from the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS), in situ aircraft data and the 3-D chemical transport model TOMCAT. MIPAS shows peak UTLS PAN concentrations over the biomass burning regions (e.g. ranging from 150 to > 200 pptv at 150 hPa) and during the summertime Asian monsoon as enhanced convection aids the vertical transport of PAN from the lower atmosphere. At 150 hPa, we find significant differences between the two MIPAS datasets in the tropics, where IMK PAN concentrations are larger by 50–100 pptv. Comparisons between MIPAS and ACE-FTS show better agreement with the UoL MIPAS PAN concentrations at 200 hPa, but with mixed results above this altitude. TOMCAT generally captures the magnitude and structure of climatological aircraft PAN profiles within the observational variability allowing it to be used to investigate the MIPAS PAN differences. TOMCAT–MIPAS comparisons show that the model is both positively (UoL) and negatively (IMK) biased against the satellite products. These results indicate that satellite PAN observations are able to detect realistic spatial variations in PAN in the UTLS, but further work is needed to resolve differences in existing retrievals to allow quantitative use of the products.
Lethal yellowing (LY) and Texas Phoenix palm decline (TPPD) are two important phytoplasma diseases of palms in Florida. Both have been responsible for major economic losses historically and remain a ...constant threat to the sustainability of palm production in the landscaping and nursery industries in Florida. These two diseases cause rapid, lethal decline in afflicted palms, so rapid detection and identification is crucial to implement appropriate management strategies to reduce further spread and losses. In this study, a qPCR assay was developed to detect and identify the causal agents of LY and TPPD. Based on sequence data of the 16S gene for the 16SrIV-A phytoplasma (LY) and the 16SrIV-D phytoplasma (TPPD), two regions were identified in the gene that possessed sufficient variation to yield amplicons with measurable differences in melting temperature based on high resolution melt analysis (HRMA). One region was in the 5' region and the other was located in the 3' region of the gene. Products from both regions yielded amplicons with significantly different melting temperatures between the two phytoplasma strains. This research allows for the detection and identification of phytoplasmas in palms rapidly by eliminating many lengthy and post-PCR steps commonly used in phytoplasma identification.
Phytoplasmas are an economically important group of plant pathogens that negatively impact a wide variety of plants in agricultural and natural ecosystems. In Florida, palm trees are essential ...elements in the nursery and landscaping industries that suffer from diseases caused by phytoplasmas that are related to each other but are classified in two different subgroups, 16SrIV-A and 16SrIV-D. In this study, a TaqMan assay was developed for digital polymerase chain reaction (dPCR) to detect both palm-infecting phytoplasmas found in Florida. When compared with real-time PCR assays and nested PCR assays, dPCR was capable of detecting the phytoplasmas at much lower concentrations than was possible by using real-time PCR and nested PCR. Additionally, the assay was capable of detecting 16SrIV-B phytoplasma as well as isolates representing the 16SrI and 16SrIII phytoplasma groups. Due to sequence identity of primer annealing regions across diverse phytoplasmas, the assay is likely to be successful for detection of a wide variety of phytoplasmas. The increased sensitivity of this dPCR assay over real-time PCR will allow for earlier detection of phytoplasma infection in palm trees, as well as for screening of salivary glands of candidate insect vector species. These advantages should aid timely management decisions to reduce disease spread and rapid determination of phytoplasma transmission by vectors.
This work focuses on the structure and physical properties of the solid solution Ba2Co1-xZnxS3 (0 ≤ x ≤ 1), a family of quasi-one-dimensional sulfides with end members Ba2CoS3 and Ba2ZnS3. The ...structure of selected compounds with increasing Zn2+ content has been analyzed using neutron diffraction, transmission electron microscopy, and extended X-ray absorption fine structure, and the physical properties have been analyzed via magnetic susceptibility and resistivity measurements. The progressive substitution of the nonmagnetic Zn2+ cation for Co2+ rapidly destroys the antiferromagnetic transition present at 46 K in the quasi-one-dimensional Ba2CoS3, leading to paramagnetic behavior down to the lowest investigated temperature (5 K) for compounds with x > 0.25. For compounds with x ≥ 0.4, a pure Curie-Weiss regime is recovered around 300 K, yielding effective moments consistent with the g factor of the tetrahedrally coordinated Co2+ previously determined for Ba2CoS3. The substitution of Zn2+ for Co2+ also removes the metallic-like behavior of Ba2CoS3, causing an increase in the value of the resistivity with all the Ba2Co1-xZnxS3 compounds showing semiconducting behavior. The negative magnetoresistance of Ba2CoS3 is improved by the substitution of Zn2+ for Co2+, with values of -6% for Ba2Co0.75Zn0.25S3, -9% for Ba2Co0.5Zn0.5S3, and -8% for Ba2Co0.25Zn0.75S3. However, there does not seem to be a correlation between the values of resistivity and magnetoresistance and the content of Zn2+, leading to the hypothesis that transport properties may be linked more closely to extrinsic properties.
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