Complete Assembly of the Genome of an Acidovorax citrulli Strain Reveals a Naturally Occurring Plasmid in This Species

Acidovorax citrulli is the causal agent of bacterial fruit blotch (BFB), a serious threat to cucurbit crop production worldwide. Based on genetic and phenotypic properties, A. citrulli strains are divided into two major groups: group I strains have been generally isolated from melon and other non-watermelon cucurbits, while group II strains are closely associated with watermelon. In a previous study, we reported the genome of the group I model strain, M6. At that time, the M6 genome was sequenced by MiSeq Illumina technology, with reads assembled into 139 contigs. Here, we report the assembly of the M6 genome following sequencing with PacBio technology. This approach not only allowed full assembly of the M6 genome, but it also revealed the occurrence of a ∼53 kb plasmid. The M6 plasmid, named pACM6, was further confirmed by plasmid extraction, Southern-blot analysis of restricted fragments and obtention of M6-derivative cured strains. pACM6 occurs at low copy numbers (average of ∼4.1 ± 1.3 chromosome equivalents) in A. citrulli M6 and contains 63 open reading frames (ORFs), most of which (55.6%) encoding hypothetical proteins. The plasmid contains several genes encoding type IV secretion components, and typical plasmid-borne genes involved in plasmid maintenance, replication and transfer. The plasmid also carries an operon encoding homologs of a Fic-VbhA toxin-antitoxin (TA) module. Transcriptome data from A. citrulli M6 revealed that, under the tested conditions, the genes encoding the components of this TA system are among the highest expressed genes in pACM6. Whether this TA module plays a role in pACM6 maintenance is still to be determined. Leaf infiltration and seed transmission assays revealed that, under tested conditions, the loss of pACM6 did not affect the virulence of A. citrulli M6. We also show that pACM6 or similar plasmids are present in several group I strains, but absent in all tested group II strains of A. citrulli

La maternidad en la adolescencia: sueño realizado y las expectativas para el futuro

This qualitative study aimed to describe the reasons that motivate an adolescent to get pregnant and her expectations about the future after the child's birth. Symbolic Interactionism was used as theoretical framework and Grounded Theory as the methodological one. Eight adolescent mothers aged between 15 and 19 years who lived the experience of caring for their children took part in the study. Data collection tools were observant participation and semi-structured interviews. Data analysis revealed that becoming a mother is an experience that might be desired and even planned. Furthermore, data showed that after the child's birth, the adolescent continues to have expectations of self-realization in order to provide a better future for herself and for her child, as revealed by the categories: Making a dream come true and Having expectations about the future. The full understanding of this experience will contribute to the practice of all professionals that provide assistance to pregnant and adolescent mothers at different levels of healthcare.Estudio cualitativo, que tuvo como objetivo describir los motivos que impulsan a la adolescente a embarazarse y cuáles son sus expectativas en cuanto al futuro, después del nacimiento del hijo. El referencial teórico fue el Interaccionismo Simbólico y la Teoría Fundamentada en los Datos el referencial metodológico. Participaron en el estudio ocho madres adolescentes, de 15 a 19 años de edad, que vivenciaban la experiencia de cuidar a los hijos. Las estrategias utilizadas de recolección de datos fueron la observación participante y la entrevista semi-estructurada. El análisis de los datos evidenció que convertirse en madre es una experiencia que puede ser deseada y hasta planificada y que después del nacimiento del bebé la adolescente continúa teniendo expectativas de realizaciones visando proporcionar un futuro mejor para sí misma y su hijo, conforme revelado en las categorías: Realizando un sueño y Teniendo expectativas en cuanto al futuro. La comprensión de esa vivencia contribuirá en la práctica de los profesionales que asisten a gestantes y madres adolescentes, en los diferentes niveles de atención.Estudo qualitativo que objetivou descrever os motivos que impulsionam a adolescente a engravidar e quais suas expectativas quanto ao futuro, após o nascimento do filho. O Interacionismo Simbólico foi referencial teórico e a Teoria Fundamentada nos Dados, o referencial metodológico. Participaram oito mães adolescentes, de 15 a 19 anos de idade, que vivenciavam a experiência de cuidar dos filhos. As estratégias utilizadas de coleta de dados foram observação participante e entrevista semi-estruturada. A análise dos dados evidenciou que tornar-se mãe é uma experiência que pode ser desejada e até planejada, e que, após o nascimento do bebê, a adolescente continua a ter expectativas de realizações visando proporcionar um futuro melhor para si e seu filho, conforme revelado nas categorias: Realizando um sonho, e Tendo expectativas quanto ao futuro. A compreensão dessa vivência contribuirá na prática dos profissionais que assistem gestantes e mães adolescentes, nos diferentes níveis de atenção.UNIFESP Programa de Pós-Graduação em EnfermagemUNIFESP Departamento de EnfermagemUNIFESP, Programa de Pós-Graduação em EnfermagemUNIFESP, Depto. de EnfermagemSciEL

Age Determination of Six Intermediate-age SMC Star Clusters with HST/ACS

We present a photometric analysis of the star clusters Lindsay 1, Kron 3, NGC339, NGC416, Lindsay 38, and NGC419 in the Small Magellanic Cloud (SMC), observed with the Hubble Space Telescope Advanced Camera for Surveys (ACS) in the F555W and F814W filters. Our color magnitude diagrams (CMDs) extend ~3.5 mag deeper than the main-sequence turnoff points, deeper than any previous data. Cluster ages were derived using three different isochrone models: Padova, Teramo, and Dartmouth, which are all available in the ACS photometric system. Fitting observed ridgelines for each cluster, we provide a homogeneous and unique set of low-metallicity, single-age fiducial isochrones. The cluster CMDs are best approximated by the Dartmouth isochrones for all clusters, except for NGC419 where the Padova isochrones provided the best fit. The CMD of NGC419 shows several main-sequence turn-offs, which belong to the cluster and to the SMC field. We thus derive an age range of 1.2-1.6 Gyr for NGC419. Interestingly, our intermediate-age star clusters have a metallicity spread of ~0.6 dex, which demonstrates that the SMC does not have a smooth, monotonic age-metallicity relation. We find an indication for centrally concentrated blue straggler star candidates in NGC416, while for the other clusters these are not present. Using the red clump magnitudes, we find that the closest cluster, NGC419 (~50kpc), and the farthest cluster, Lindsay 38 (~67kpc), have a relative distance of ~17kpc, which confirms the large depth of the SMC.Comment: 25 pages, 45 Figure

Emission-Line Galaxy Surveys as Probes of the Spatial Distribution of Dwarf Galaxies. I. The University of Michigan Survey

Objective-prism surveys which select galaxies on the basis of line-emission are extremely effective at detecting low-luminosity galaxies and constitute some of the deepest available samples of dwarfs. In this study, we confirm that emission-line galaxies (ELGs) in the University of Michigan (UM) objective-prism survey (MacAlpine et al. 1977-1981) are reliable tracers of large-scale structure, and utilize the depth of the samples to examine the spatial distribution of low-luminosity (M$_{B} >$ -18.0) dwarfs relative to higher luminosity giant galaxies (M$_{B} \leq$ -18.0) in the Updated Zwicky Catalogue (Falco et al. 1999). New spectroscopic data are presented for 26 UM survey objects. We analyze the relative clustering properties of the overall starbursting ELG and normal galaxy populations, using nearest neighbor and correlation function statistics. This allows us to determine whether the activity in ELGs is primarily caused by gravitational interactions. We conclude that galaxy-galaxy encounters are not the sole cause of activity in ELGs since ELGs tend to be more isolated and are more often found in the voids when compared to their normal galaxy counterparts. Furthermore, statistical analyses performed on low-luminosity dwarf ELGs show that the dwarfs are less clustered when compared to their non-active giant neighbors. The UM dwarf samples have greater percentages of nearest neighbor separations at large values and lower correlation function amplitudes relative to the UZC giant galaxy samples. These results are consistent with the expectations of galaxy biasing.Comment: 17 pages, 4 tables, 10 figures. Accepted for publication in the Ap

Properties of Galaxies in and around Voids

Two surveys for intrinsically faint galaxies towards nearby voids have been conducted at the MPI f\"ur Astronomie, Heidelberg. One selected targets from a new diameter limited ($\Phi \ge 5''$) catalog with morphological criteria while the other used digitized objective prism Schmidt plates to select mainly HII dwarf galaxies. For some 450 galaxies, redshifts and other optical data were obtained. We studied the spatial distribution of the sample objects, their luminosity function, and their intrinsic properties. Most of the galaxies belong to already well known sheets and filaments. But we found about a dozen highly isolated galaxies in each sample (nearest neighborhood distance $\ge 3 h_{75}^{-1} Mpc$). These tend to populate additional structures and are not distributed homogeneously throughout the voids. As our results on 'void galaxies' still suffer from small sample statistics, I also tried to combine similar existing surveys of nearby voids to get further hints on the larger structure and on the luminosity function of the isolated galaxies. No differences in the luminosity function of sheet and void galaxies could be found. The optical and infrared properties of both samples are in the normal range for samples dominated by late-type dwarfs. Follow-up HI studies show that the isolated dwarfs in both samples have unusual high amount of neutral gas for a given luminosity.Comment: 10 pages, 4 figures, latex, to appear in the proceedings of the 'Ringberg workshop on Large Scale Structure', hold Sep. 23-28, 199

Low-resolution spectroscopy of main sequence stars belonging to 12 Galactic globular clusters. I. CH and CN band strength variations

Globular clusters show abundance variations for light elements that are not yet well understood. The preferred explanation involves a self-enrichment scenario, with two subsequent generations of stars. Observations of main sequence stars allow us to investigate the signature of this chemically processed material without the complicating effects of internal mixing. Our goal is to investigate the C-N anti-correlation with low-resolution spectroscopy of 20-50 stars fainter than the first dredge-up in seven globular clusters (NGC288, NGC1851, NGC5927, NGC6352, NGC6388, and Pal12) with different properties. We complemented our observations with 47~Tuc archival data, with four additional clusters from the literature (M15, M22, M55, NGC362), and with additional literature data on NGC288. In this first paper, we measured the strength of CN and CH band indices, and we investigated the anti-correlation and bimodality of these indices. We compared r_CN, the ratio of stars belonging to the CN-strong and weak groups, with 15 different cluster parameters. We clearly see bimodal anti-correlation of the CH and CN band stregths in the metal-rich clusters (Pal12, 47Tuc, NGC6352, NGC5927). Only M15 among the metal-poor clusters shows a clearly bimodal anti-correlation. We found weak correlations (sligthly above 1 sigma) of r_CN with the cluster orbital parameters, present-day total mass, cluster concentration, and age. Our findings support the self-enrichment scenario, and suggest that the occurrence of more than two major generations of stars in a GGC should be rare. Small additional generations (<10-20% of the total) would be difficult to detect with our samples. The first generation, which corresponds to the CN-weak stars, usually contains more stars than the second one (=0.82+/-0.29), as opposed to results based on the Na-O anti-correlations.Comment: 18 pages, 10 figures, 1 electronic table, accepted for publication in A&A (language edited version

Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys - II. The unique LMC cluster ESO 121-SC03

We present the results of photometric measurements from images of the LMC cluster ESO 121-SC03 taken with HST/ACS. Our resulting CMD reaches 3 magnitudes below the main-sequence turn-off, representing the deepest observation of this cluster to date. We also present similar photometry from ACS imaging of the accreted Sagittarius dSph cluster Pal. 12, used in this work as a comparison cluster. From analysis of its CMD, we obtain estimates for the metallicity and reddening of ESO 121-SC03: [Fe/H] = -0.97 +/- 0.10 and E(V-I) = 0.04 +/- 0.02, in excellent agreement with previous studies. The observed horizontal branch level in ESO 121-SC03 suggests this cluster may lie 20 per cent closer to us than does the centre of the LMC. ESO 121-SC03 also possesses a significant population of blue stragglers, which we briefly discuss. Our new photometry allows us to undertake a detailed study of the age of ESO 121-SC03 relative to Pal. 12 and the Galactic globular cluster 47 Tuc. Our main result is that ESO 121-SC03 is 73 +/- 4 per cent the age of 47 Tuc, and 91 +/- 5 per cent the age of Pal. 12. Pal. 12 is 79 +/- 6 per cent as old as 47 Tuc, consistent with previous work. Our result corresponds to an absolute age for ESO 121-SC03 in the range 8.3-9.8 Gyr depending on the age assumed for 47 Tuc, therefore confirming ESO 121-SC03 as the only known cluster to lie squarely within the LMC age gap. We briefly discuss a suggestion from earlier work that ESO 121-SC03 may have been accreted into the LMC system.Comment: 13 pages, 6 figures, accepted for publication in MNRA

Maternidade na adolescência: sonho realizado e expectativas quanto ao futuro

Estudo qualitativo, que objetivou descrever os motivos que impulsionam a adolescente a engravidar e quais suas expectativas quanto ao futuro, após o nascimento do filho. O Interacionismo Simbólico foi referencial teórico e a Teoria Fundamentada nos Dados o referencial metodológico. Participaram oito mães adolescentes, de 15 a 19 anos de idade, que vivenciavam a experiência de cuidar dos filhos. As estratégias utilizadas de coleta de dados foram observação participante e entrevista semi-estruturada. A análise dos dados evidenciou que tornar-se mãe é uma experiência que pode ser desejada e até planejada e que a após o nascimento do bebê a adolescente continua a ter expectativas de realizações visando proporcionar um futuro melhor para si e seu filho, conforme revelado nas categorias: Realizando um sonho, e Tendo expectativas quanto ao futuro. A compreensão dessa vivência contribuirá na prática dos profissionais que assistem gestantes e mães adolescentes, nos diferentes níveis de atenção

Effective connectivity reveals strategy differences in an expert calculator

Mathematical reasoning is a core component of cognition and the study of experts defines the upper limits of human cognitive abilities, which is why we are fascinated by peak performers, such as chess masters and mental calculators. Here, we investigated the neural bases of calendrical skills, i.e. the ability to rapidly identify the weekday of a particular date, in a gifted mental calculator who does not fall in the autistic spectrum, using functional MRI. Graph-based mapping of effective connectivity, but not univariate analysis, revealed distinct anatomical location of “cortical hubs” supporting the processing of well-practiced close dates and less-practiced remote dates: the former engaged predominantly occipital and medial temporal areas, whereas the latter were associated mainly with prefrontal, orbitofrontal and anterior cingulate connectivity. These results point to the effect of extensive practice on the development of expertise and long term working memory, and demonstrate the role of frontal networks in supporting performance on less practiced calculations, which incur additional processing demands. Through the example of calendrical skills, our results demonstrate that the ability to perform complex calculations is initially supported by extensive attentional and strategic resources, which, as expertise develops, are gradually replaced by access to long term working memory for familiar material

The population of variable stars in M54 (NGC6715)

We present new B, V and I CCD time-series photometry for 177 variable stars in a 13'X 13' field centered on the globular cluster M54 (lying at the center of the Sagittarius dwarf spheroidal galaxy), 94 of which are newly identified variables. The total sample is composed of 2 anomalous Cepheids, 144 RR Lyrae stars (108 RR0 and 36 RR1), 3 SX Phoenicis, 7 eclipsing binaries (5 W UMA and 2 Algol binaries), 3 variables of uncertain classification and 18 long-period variables. The large majority of the RR Lyrae variables likely belong to M54. Ephemerides are provided for all the observed short-period variables. The pulsational properties of the M54 RR Lyrae variables are close to those of Oosterhoff I clusters, but a significant number of long-period ab type RR Lyrae are present. We use the observed properties of the RR Lyrae to estimate the reddening and the distance modulus of M54, E(B-V)=0.16 +/- 0.02 and (m-M)_0=17.13 +/- 0.11, respectively, in excellent agreement with the most recent estimates. The metallicity has been estimated for a subset of 47 RR Lyrae stars, with especially good quality light curves, from the Fourier parameters of the V light curve. The derived metallicity distribution has a symmetric bell shape, with a mean of =-1.65 and a standard deviation sigma=0.16 dex. Seven stars have been identified as likely belonging to the Sagittarius galaxy, based on their too high or too low metallicity. This evidence, if confirmed, might suggest that old stars in this galaxy span a wide range of metallicities.Comment: 15 pages, 11 figures, accepted for publication by MNRA