31 research outputs found
Wider Access to Genotypic Space Facilitates Loss of Cooperation in a Bacterial Mutator
Understanding the ecological, evolutionary and genetic factors that affect the expression of cooperative behaviours is a topic of wide biological significance. On a practical level, this field of research is useful because many pathogenic microbes rely on the cooperative production of public goods (such as nutrient scavenging molecules, toxins and biofilm matrix components) in order to exploit their hosts. Understanding the evolutionary dynamics of cooperation is particularly relevant when considering long-term, chronic infections where there is significant potential for intra-host evolution. The impact of responses to non-social selection pressures on social evolution is arguably an under-examined area. In this paper, we consider how the evolution of a non-social trait – hypermutability – affects the cooperative production of iron-scavenging siderophores by the opportunistic human pathogen Pseudomonas aeruginosa. We confirm an earlier prediction that hypermutability accelerates the breakdown of cooperation due to increased sampling of genotypic space, allowing mutator lineages to generate non-cooperative genotypes with the ability to persist at high frequency and dominate populations. This may represent a novel cost of hypermutability
The Complete Genome Sequence of ‘Candidatus Liberibacter solanacearum’, the Bacterium Associated with Potato Zebra Chip Disease
Zebra Chip (ZC) is an emerging plant disease that causes aboveground decline of
potato shoots and generally results in unusable tubers. This disease has led to
multi-million dollar losses for growers in the central and western United States
over the past decade and impacts the livelihood of potato farmers in Mexico and
New Zealand. ZC is associated with ‘Candidatus
Liberibacter solanacearum’, a fastidious alpha-proteobacterium that is
transmitted by a phloem-feeding psyllid vector, Bactericera
cockerelli Sulc. Research on this disease has been hampered by a
lack of robust culture methods and paucity of genome sequence information for
‘Ca. L. solanacearum’. Here we present the
sequence of the 1.26 Mbp metagenome of ‘Ca. L.
solanacearum’, based on DNA isolated from potato psyllids. The coding
inventory of the ‘Ca. L. solanacearum’ genome was
analyzed and compared to related Rhizobiaceae to better
understand ‘Ca. L. solanacearum’ physiology and
identify potential targets to develop improved treatment strategies. This
analysis revealed a number of unique transporters and pathways, all potentially
contributing to ZC pathogenesis. Some of these factors may have been acquired
through horizontal gene transfer. Taxonomically, ‘Ca. L.
solanacearum’ is related to ‘Ca. L.
asiaticus’, a suspected causative agent of citrus huanglongbing, yet many
genome rearrangements and several gene gains/losses are evident when comparing
these two Liberibacter. species. Relative to ‘Ca. L.
asiaticus’, ‘Ca. L. solanacearum’ probably
has reduced capacity for nucleic acid modification, increased amino acid and
vitamin biosynthesis functionalities, and gained a high-affinity iron transport
system characteristic of several pathogenic microbes
SOSORT consensus paper: school screening for scoliosis. Where are we today?
This report is the SOSORT Consensus Paper on School Screening for Scoliosis discussed at the 4th International Conference on Conservative Management of Spinal Deformities, presented by SOSORT, on May 2007. The objectives were numerous, 1) the inclusion of the existing information on the issue, 2) the analysis and discussion of the responses by the meeting attendees to the twenty six questions of the questionnaire, 3) the impact of screening on frequency of surgical treatment and of its discontinuation, 4) the reasons why these programs must be continued, 5) the evolving aim of School Screening for Scoliosis and 6) recommendations for improvement of the procedure
Notes for genera: basal clades of Fungi (including Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota)
Compared to the higher fungi (Dikarya), taxonomic and evolutionary studies on the basal clades of fungi are fewer in number. Thus, the generic boundaries and higher ranks in the basal clades of fungi are poorly known. Recent DNA based taxonomic studies have provided reliable and accurate information. It is therefore necessary to compile all available information since basal clades genera lack updated checklists or outlines. Recently, Tedersoo et al. (MycoKeys 13:1--20, 2016) accepted Aphelidiomycota and Rozellomycota in Fungal clade. Thus, we regard both these phyla as members in Kingdom Fungi. We accept 16 phyla in basal clades viz. Aphelidiomycota, Basidiobolomycota, Blastocladiomycota, Calcarisporiellomycota, Caulochytriomycota, Chytridiomycota, Entomophthoromycota, Glomeromycota, Kickxellomycota, Monoblepharomycota, Mortierellomycota, Mucoromycota, Neocallimastigomycota, Olpidiomycota, Rozellomycota and Zoopagomycota. Thus, 611 genera in 153 families, 43 orders and 18 classes are provided with details of classification, synonyms, life modes, distribution, recent literature and genomic data. Moreover, Catenariaceae Couch is proposed to be conserved, Cladochytriales Mozl.-Standr. is emended and the family Nephridiophagaceae is introduced
Phaffia rhodozyma and Xanthophyllomyces dendrorhous: astaxanthin-producing yeasts of biotechnological importance
The nutritional value of carotenoids such as α- and β-carotene, β-cryptoxanthin and astaxanthin has been known for many years, and their antioxidant properties and their efficiency in the prevention of certain human diseases have also been claimed.Accordingly, interest in these compounds from a nutritional aspect has increased substantially. Phaffia rhodozyma andXanthophyllomyces dendrorhous are the most promising industrial sources of astaxanthin. Since Phaffia was described in 1972, many studies of the phylogenesis, and biochemical and biotechnological properties of this red-pigmented yeast have been performed. The commercial demand for astaxanthin is increasing and, although biological production is still not economical, progress is being made in strain improvement and in fermentation methods
Ferric ion (hydr)oxo clusters in the “Venus flytrap” cleft of FbpA : Mössbauer, calorimetric and mass spectrometric studies
Isothermal calorimetric studies of the binding of iron(III) citrate to ferric ion binding protein from Neisseria gonorrhoeae suggested the complexation of a tetranuclear iron(III) cluster as a single step binding event (apparent binding constant K appITC = 6.0(5) × 105 M−1). High-resolution Fourier transform ion cyclotron resonance mass spectrometric data supported the binding of a tetranuclear oxo(hydroxo) iron(III) cluster of formula [Fe4O2(OH)4(H2O)(cit)]+ in the interdomain binding cleft of FbpA. The mutant H9Y-nFbpA showed a twofold increase in the apparent binding constant [K appITC = 1.1(7) × 106 M−1] for the tetranuclear iron(III) cluster compared to the wild-type protein. Mössbauer spectra of Escherichia coli cells overexpressing FbpA and cultured in the presence of added 57Fe citrate were indicative of the presence of dinuclear and polynuclear clusters. FbpA therefore appears to have a strong affinity for iron clusters in iron-rich environments, a property which might endow the protein with new biological functions