Nematode distribution and damage to yam in central and eastern Uganda

Yams (Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata, D. bulbisiana, D. burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed byMeloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data suggested that differences in susceptibility to P. sudanensis occur between yam cultivars and species

Combined exome and whole-genome sequencing identifies mutations in ARMC4 as a cause of primary ciliary dyskinesia with defects in the outer dynein arm

Primary ciliary dyskinesia (PCD) is a rare, genetically heterogeneous ciliopathy disorder affecting cilia and sperm motility. A range of ultrastructural defects of the axoneme underlie the disease, which is characterised by chronic respiratory symptoms and obstructive lung disease, infertility and body axis laterality defects. We applied a next-generation sequencing approach to identify the gene responsible for this phenotype in two consanguineous families

Roles for Drosophila melanogaster myosin IB in maintenance of enterocyte brush-border structure and resistance to the bacterial pathogen Pseudomonas entomophila

Author Posting. © American Society for Cell Biology, 2007. This article is posted here by permission of American Society for Cell Biology for personal use, not for redistribution. The definitive version was published in Molecular Biology of the Cell 18 (2007): 4625-4636, doi:10.1091/mbc.E07-02-0191.Drosophila myosin IB (Myo1B) is one of two class I myosins in the Drosophila genome. In the larval and adult midgut enterocyte, Myo1B is present within the microvillus (MV) of the apical brush border (BB) where it forms lateral tethers between the MV membrane and underlying actin filament core. Expression of green fluorescent protein-Myo1B tail domain in the larval gut showed that the tail domain is sufficient for localization of Myo1B to the BB. A Myo1B deletion mutation exhibited normal larval gut physiology with respect to food uptake, clearance, and pH regulation. However, there is a threefold increase in terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive enterocyte nuclei in the Myo1B mutant. Ultrastructural analysis of mutant midgut revealed many perturbations in the BB, including membrane tethering defects, MV vesiculation, and membrane shedding. The apical localization of both singed (fascin) and Dmoesin is impaired. BBs isolated from mutant and control midgut revealed that the loss of Myo1B causes the BB membrane and underlying cytoskeleton to become destabilized. Myo1B mutant larvae also exhibit enhanced sensitivity to oral infection by the bacterial pathogen Pseudomonas entomophila, and severe cytoskeletal defects are observed in the BB of proximal midgut epithelial cells soon after infection. Resistance to P. entomophila infection is restored in Myo1B mutant larvae expressing a Myo1B transgene. These results indicate that Myo1B may play a role in the local midgut response pathway of the Imd innate immune response to Gram-negative bacterial infection.This work was supported by National Institutes of Health grants DK-25387 (to M.S.M.), DK-55389 (to Jon Morrow, Yale School of Medicine), and GM-52857 (to L.G.T.) and a research grant from the Crohns and Colitis Foundation of America (to M.S.M.)

Low Frequency Vibrations Disrupt Left-Right Patterning in the Xenopus Embryo

The development of consistent left-right (LR) asymmetry across phyla is a fascinating question in biology. While many pharmacological and molecular approaches have been used to explore molecular mechanisms, it has proven difficult to exert precise temporal control over functional perturbations. Here, we took advantage of acoustical vibration to disrupt LR patterning in Xenopus embryos during tightly-circumscribed periods of development. Exposure to several low frequencies induced specific randomization of three internal organs (heterotaxia). Investigating one frequency (7 Hz), we found two discrete periods of sensitivity to vibration; during the first period, vibration affected the same LR pathway as nocodazole, while during the second period, vibration affected the integrity of the epithelial barrier; both are required for normal LR patterning. Our results indicate that low frequency vibrations disrupt two steps in the early LR pathway: the orientation of the LR axis with the other two axes, and the amplification/restriction of downstream LR signals to asymmetric organs

Fertility desires, family planning use and pregnancy experience: longitudinal examination of urban areas in three African countries

Background Many women have inconsistent fertility desires and contraceptive use behaviors. This increases their risk of unintended pregnancies. Inconsistencies may reflect barriers to family planning (FP) use but may also reflect ambivalence toward future childbearing. Using urban data from Kenya, Nigeria, and Senegal, this study examines the role of fertility desires and FP use behaviors on pregnancy experience over a 2-year follow-up period. Methods Data come from baseline and 2-year follow-up among urban women interviewed in Kenya, Nigeria, and Senegal. At baseline (2010/2011), women were asked about their future fertility desires (want child soon, want to delay >2 years, does not want) and current FP use. At midterm (2012/2013), women were asked if they were currently pregnant or had a birth in the 2-year period. We examine the association between baseline fertility desires and FP use with pregnancy experience and desirability of an experienced pregnancy. Results In the 2-year follow-up period, 27–39 % of women in union experienced a pregnancy or birth. In Kenya and Nigeria, 30–35 % of women using a modern FP method experienced a pregnancy/birth; the percentage with a pregnancy/birth was slightly higher among women not using at baseline (41 % in both countries). In Senegal, the distinction between pregnancy experience between users and non-users was greater (16 % vs. 31 %, respectively). In all countries, pregnancy was less common among users of long-acting and permanent methods; only a small percentage of women use these methods. Women not wanting any(more) children were the least likely to experience a pregnancy in the 2-year follow-up period. No differences were observed between those who wanted to delay and those who wanted soon. Multivariate findings demonstrate distinctions in pregnancy experience by fertility desires among modern FP users. Non-users have similar pregnancy experience by fertility desires. Conclusions Fertility desires are not stable; providers need to consider the fluidity of fertility desires in counseling clients. Programs focusing on new FP users may miss women who are the most motivated to avoid a pregnancy and need to switch to a more effective method; this will result in less unintended pregnancies overall

Nematode distribution and damage to yam in Central and Eastern Uganda

Yams (Dioscorea spp.) are food crops of growing significance in sub Saharan Africa. Unfortunately, nematodes are major pests to their production. A study was undertaken in major yam growing areas of Uganda to investigate the association of plant parasitic nematodes with damage symptoms. Nematodes were assessed from tubers, roots and surrounding soil for seven cultivars belonging to Dioscorea alata, D. bulbisiana, D.burkilliana and D. cayenensis at harvest. Pratylenchus sudanensis was found in the greatest density and was followed by Meloidogyne spp. Higher densities of both nematodes were observed in the tubers rather than roots. Although symptoms of cracking and galling were relatively low, P. sudanensis incidence was strongly associated with cracking and Meloidogyne spp. with galling. Pratylenchus sudanensis and Meloidogyne spp. incidence their associated damage were, however, negatively correlated, suggesting inter-species competition. Principal components analysis of data suggested that differences in susceptibility to P. sudanensis occur between yam cultivars and species.Les ignames (Dioscorea spp.) sont une culture alimentaire d’importance croissante en Afrique sub–saharienne.Malheureusement, les nématodes sont des parasites majeurs qui gênent sa production. Une étude était menéedans les principales régions productrices de l’igname en Ouganda en vue de pouvoir mener investigation surl’association des nématodes parasitant les plantes avec les symptômes de dommages. Les nématodes étaientévalués à partir des racines, tubercules, et sol environnant pour 7 cultivars appartenant à Dioscorea alata, D.bulbisiana, D. burkilliana et D. cayenensis à la récolte. Pratylenchus sudanensis était considérée l’espèce à plushaute densité et était suivie par Meloidogyne spp. Des densités plus élevées des nématodes étaient observéesplus dans les tubercules que dans les racines. Bien que les symptômes de craquelures et d’irritations étaientrelativement bas, P.Sudanensis et Meloidogyne spp. étaient respectivement associées à la craquelure et à l’irritation.Pratylenctus Sudanensis et Meloidogyne spp. présentaient des damages associés, qui étaient cependant négativementcorrélés suggérant une compétition inter-espèces. L’analyse principale des données a suggéré des différences à lasusceptibilité du P. Sudanensis surviennent entre cultivars et espèces d’ignames

Electrochemical Stability and Postmortem Studies of Pt/SiC Catalysts for Polymer Electrolyte Membrane Fuel Cells

In the presented work, the electrochemical stability of platinized silicon carbide is studied. Postmortem transmission electron microscopy and X-ray photoelectron spectroscopy were used to document the change in the morphology and structure upon potential cycling of Pt/SiC catalysts. Two different potential cycle aging tests were used in order to accelerate the support corrosion, simulating start-up/shutdown and load cycling. On the basis of the results, we draw two main conclusions. First, platinized silicon carbide exhibits improved electrochemical stability over platinized active carbons. Second, silicon carbide undergoes at least mild oxidation if not even silicon leaching