On the relationship of normal modes to local modes in molecular vibrations

A simple model for the effective vibrational hamiltonian of the XH stretching vibrations in H2O, NH3 and CH4 is considered, based on a morse potential function for the bond stretches plus potential and kinetic energy coupling between pairs of bond oscillators. It is shown that this model can be set up as a matrix in local mode basis functions, or as a matrix in normal mode basis functions, leading to identical results. The energy levels obtained exhibit normal mode patterns at low vibrational excitation, and local mode patterns at high excitation. When the hamiltonian is set up in the normal mode basis it is shown that Darling-Dennison resonances must be included, and simple relations are found to exist between the xrs, gtt, and Krrss anharmonic constants (where the Darling-Dennison coefficients are denoted K) due to their contributions from morse anharmonicity in the bond stretches. The importance of the Darling-Dennison resonances is stressed. The relationship of the two alternative representations of this local mode/normal mode model are investigated, and the potential uses and limitations of the model are discussed.

Local modes and x,K relations for ethene and propadiene

The results recently obtained by Mills and Robiette on local-mode effects in H2O, NH3 and CH4 type molecules are extended to ethene (C2H4) and propadiene (C3H4) type molecules. General relations among the anharmonic xrs constants and the Darling-Dennison Krrss constants for the stretching vibrations are derived, called “x,K relations”, which allow local-mode effects to be generated by adding the appropriate anharmonic and Darling-Dennison constants to the familiar normal-mode model of molecular vibrations. The general utility of x,K relations is discussed, and the results are reviewed for the molecular types for which they have so far been derived.

Anharmonicity and local mode effects in the vibrational spectrum of NiCO4 and Co(CO)3NO

Previously published data on the vibrational fundamentals and overtones of the carbonyl stretching modes of Ni(CO)4 and Co(CO)3NO are reinterpreted using the recent model of Mills and Robiette, including Darling-Dennison resonances and local mode effects. The harmonic wavenumber θm and anharmonicity constant xm associated with the carbonyl and nitrosyl stretching modes are derived, and the 13C and 18O isotopic shifts are discussed in relation to the harmonic and anharmonic force field.

Phylogenetic relationships of the Fox (Forkhead) gene family in the Bilateria

The Forkhead or Fox gene family encodes putative transcription factors. There are at least four Fox genes in yeast, 16 in Drosophila melanogaster (Dm) and 42 in humans. Recently, vertebrate Fox genes have been classified into 17 groups named FoxA to FoxQ [Genes Dev. 14 (2000) 142]. Here, we extend this analysis to invertebrates, using available sequences from D. melanogaster, Anopheles gambiae (Ag), Caenorhabditis elegans (Ce), the sea squirt Ciona intestinalis (Ci) and amphioxus Branchiostoma floridae (Bf), from which we also cloned several Fox genes. Phylogenetic analyses lend support to the previous overall subclassification of vertebrate genes, but suggest that four subclasses (FoxJ, L, N and Q) could be further subdivided to reflect their relationships to invertebrate genes. We were unable to identify orthologs of Fox subclasses E, H, I, J, M and Q1 in D. melanogaster, A. gambiae or C. elegans, suggesting either considerable loss in ecdysozoans or the evolution of these subclasses in the deuterostome lineage. Our analyses suggest that the common ancestor of protostomes and deuterostomes had a minimum complement of 14 Fox genes. (C) 2003 Elsevier B.V. All rights reserved.

Proceedings of the Rank Forum on Vitamin D

The Rank Forum on Vitamin D was held on 2nd and 3rd July 2009 at the University of Surrey, Guildford, UK. The workshop consisted of a series of scene-setting presentations to address the current issues and challenges concerning vitamin D and health, and included an open discussion focusing on the identification of the concentrations of serum 25-hydroxyvitamin D (25(OH)D) (a marker of vitamin D status) that may be regarded as optimal, and the implications this process may have in the setting of future dietary reference values for vitamin D in the UK. The Forum was in agreement with the fact that it is desirable for all of the population to have a serum 25(OH)D concentration above 25 nmol/l, but it discussed some uncertainty about the strength of evidence for the need to aim for substantially higher concentrations (25(OH)D concentrations . 75 nmol/l). Any discussion of ‘optimal’ concentration of serum 25(OH)D needs to define ‘optimal’ with care since it is important to consider the normal distribution of requirements and the vitamin D needs for a wide range of outcomes. Current UK reference values concentrate on the requirements of particular subgroups of the population; this differs from the approaches used in other European countries where a wider range of age groups tend to be covered. With the re-emergence of rickets and the public health burden of low vitamin D status being already apparent, there is a need for urgent action from policy makers and risk managers. The Forum highlighted concerns regarding the failure of implementation of existing strategies in the UK for achieving current vitamin D recommendations.

British container breeding mosquitoes: the impact of urbanisation and climate change on community composition and phenology

The proliferation of artificial container habitats in urban areas has benefitted urban adaptable mosquito species globally. In areas where mosquitoes transmit viruses and parasites, it can promote vector population productivity and fuel mosquito-borne disease outbreaks. In Britain, storage of water in garden water butts is increasing, potentially expanding mosquito larval habitats and influencing population dynamics and mosquito-human contact. Here we show that the community composition, abundance and phenology of mosquitoes breeding in experimental water butt containers were influenced by urbanisation. Mosquitoes in urban containers were less species-rich but present in significantly higher densities (100.4±21.3) per container than those in rural containers (77.7±15.1). Urban containers were dominated by Culex pipiens (a potential vector of West Nile Virus [WNV]) and appear to be increasingly exploited by Anopheles plumbeus (a human-biting potential WNV and malaria vector). Culex phenology was influenced by urban land use type, with peaks in larval abundances occurring earlier in urban than rural containers. Among other factors, this was associated with an urban heat island effect which raised urban air and water temperatures by 0.9°C and 1.2°C respectively. Further increases in domestic water storage, particularly in urban areas, in combination with climate changes will likely alter mosquito population dynamics in the UK.

En attendant Sarko? France’s mainstream Right and Centre, 2012-2014

In winning the municipal elections of March 2014, France’s mainstream opposition – the Centrists and the Union pour un Mouvement Populaire (UMP) – benefited not only from the unpopularity of the Left in power, but also from its own (partial) reconstruction. The Centrists had reorganised; the UMP had reaffirmed its right-wing programme and drawn strength from the opposition social movements launched in 2013. The European elections of 2014, however, demonstrated the limitations of this reconstruction. Their weak institutionalisation – the original sin of France’s Right and centre-Right – left internal ideological differences and (above all) personal rivalries unchecked within both forces. These tensions were compounded, in the UMP, by a series of financial scandals. At their heart was former president Nicolas Sarkozy, still the activists’ darling, ever more clearly a candidate for 2017, but also more hobbled by judicial investigations.

Concordant Phylogeographies of 2 Malaria Vectors Attest to Common Spatial and Demographic Histories

The phylogeography of South American lineages is a topic of heated debate. Although a single process is unlikely to describe entire ecosystems, related species, which incur similar habitat limitations, can inform the history for a subsection of assemblages. We compared the phylogeographic patterns of the cytochrome oxidase I marker from Anopheles triannulatus (N = 72) and previous results for A. darlingi (N = 126) in a broad portion of their South American distributions. Both species share similar population subdivisions, with aggregations northeast of the Amazon River, in southern coastal Brazil and 2 regions in central Brazil. The average (ST) between these groups was 0.39 for A. triannulatus. Populations northeast of the Amazon and in southeastern Brazil are generally reciprocally monophyletic to the remaining groups. Based on these initial analyses, we constructed the a priori hypothesis that the Amazon and regions of high declivity pose geographic barriers to dispersal in these taxa. Mantel tests confirmed that these areas block gene flow for more than 1000 km for both species. The efficacy of these impediments was tested using landscape genetics, which could not reject our a priori hypothesis but did reject simpler scenarios. Results form summary statistics and phylogenetics suggest that both lineages originated in central Amazonia (south of the Amazon River) during the late Pleistocene (579 000 years ago) and that they followed the same paths of expansion into their contemporary distributions. These results may have implications for other species sharing similar ecological limitations but probably are not applicable as a general paradigm of Neotropical biogeography.

Segregation effects according to the evolutionary stage of galaxy groups

We study segregation phenomena in 57 groups selected from the 2dF Percolation-Inferred Galaxy Groups (2PIGG) catalogue of galaxy groups. The sample corresponds to those systems located in areas of at least 80 per cent redshift coverage out to 10 times the radius of the groups. The dynamical state of the galaxy systems was determined after studying their velocity distributions. We have used the Anderson-Darling test to distinguish relaxed and non-relaxed systems. This analysis indicates that 84 per cent of groups have galaxy velocities consistent with the normal distribution, while 16 per cent of them have more complex underlying distributions. Properties of the member galaxies are investigated taking into account this classification. Our results indicate that galaxies in Gaussian groups are significantly more evolved than galaxies in non-relaxed systems out to distances of similar to 4R(200), presenting significantly redder (B - R) colours. We also find evidence that galaxies with M(R) <= -21.5 in Gaussian groups are closer to the condition of energy equipartition.

Unusually short tandem repeats appear to reach chromosome ends of Rhynchosciara americana (Diptera: Sciaridae)

The characterisation of sequences at chromosome ends of Rhynchosciara americana was continued with the screening of a genomic library using as a probe a short repeat identified in a previous report (M-22, 22 bp) which was found to be specific for noncentromeric termini of this species. Simple repeats, complex tandem and apparently dispersed repeats were present in the genomic clones analysed. Repetitive sequences do not define individual chromosome tips as they were found in all noncentromeric ends. A novel and unusually short tandem repeat type for dipteran chromosome ends (named M-16) composed of 16 nucleotides and frequently associated with M-22 arrays was characterised in this work. Islands of M-16 and M-22 tandem repeats were found in all the genomic clones analysed. Individual probes representative of each repetitive element hybridised not only to all noncentromeric ends of R. americana chromosomes but also to inter-telomeric bridges. This contrasted with the other repeat types which displayed sub-telomeric localisation as seen by double detection of hybridised probe and telomeric reverse transcriptase. Some stretches composed of M-16 and M-22 tandem repeats localised in different regions of the analysed genomic clones were either identical or showed sequence similarity that was unexpectedly higher than the mean sequence similarity observed among repeats within each of their tandem arrays. The occurrence of segmental duplications, as deduced by sequence analyses involving the two repeats that appeared to reach chromosome ends, might indicate the involvement of this type of duplication process in the chromosome end maintenance in this species.

Curiously composite structures of a retrotransposon and a complex repeat associated with chromosome ends of Rhynchosciara americana (Diptera: Sciaridae)

In Drosophila, telomere retrotransposons counterbalance the loss of telomeric DNA. The exceptional mechanism of telomere recovery characterized in Drosophila has not been found in lower dipterans (Nematocera). However, a retroelement resembling a telomere transposon and termed ""RaTART"" has been described in the nematoceran Rhynchosciara americana. In this work, DNA and protein sequence analyses, DNA cloning, and chromosomal localization of probes obtained either by PCR or by screening a genomic library were carried out in order to examine additional features of this retroelement. The analyses performed raise the possibility that RaTART represents a genomic clone composed of distinct repetitive elements, one of which is likely to be responsible for its apparent enrichment at chromosome ends. RaTART sequence in addition allowed to assess a novel subtelomeric region of R. americana chromosomes that was analyzed in this work after subcloning a DNA fragment from a phage insert. It contains a complex repeat that is located in the vicinity of simple and complex tandem repeats characterized previously. Quantification data suggest that the copy number of the repeat is significantly lower than that observed for the ribosomal DNA in the salivary gland of R. americana. A short insertion of the RaTART was identified in the cloned segment, which hybridized preferentially to subtelomeres. Like RaTART, it displays truncated sequences related to distinct retrotransposons, one of which has a conceptual translation product with significant identity with an endonuclease from a lepidopteran retrotransposon. The composite structure of this DNA stretch probably reflects mobile element activity in the subtelomeric region analyzed in this work.

Effects of Plasmodium gallinaceum on hemolymph physiology of Aedes aegypti during parasite development

Insect disease vectors show diminished fecundity when infected with Plasmodium. This phenomenon has already been demonstrated in laboratory models such as Aedes aegypti, Anopheles gambiae and Anopheles stephensi. This study demonstrates several changes in physiological processes of A. aegypti occurring upon infection with Plasmodium gallinaceum, such as reduced ecdysteroid levels in hemolymph as well as altered expression patterns for genes involved in vitellogenesis, lipid transport and immune response. Furthermore, we could show that P. gallinaceum infected A. aegypti presented a reduction in reproductive fitness, accompanied by an activated innate immune response and increase in lipophorin expression, with the latter possibly representing a nutritional resource for Plasmodium sporozoites. (C) 2010 Elsevier Ltd. All rights reserved.

Epidemiology and control of frontier malaria in Brazil: lessons from community-based studies in rural Amazonia

We describe the epidemiology of malaria in a frontier agricultural settlement in Brazilian Amazonia. We analysed the incidence of slide-confirmed symptomatic infections diagnosed between 2001 and 2006 in a cohort of 531 individuals (2281.53 person-years of follow-up) and parasite prevalence data derived from four cross-sectional surveys. Overall, the incidence rates of Plasmodium vivax and P. falciparaum were 20.6/100 and 6.8/100 person-years at risk, respectively, with a marked decline in the incidence of both species (81.4 and 56.8%, respectively) observed between 2001 and 2006. PCR revealed 5.4-fold more infections than conventional microscopy in population-wide cross-sectional surveys carried out between 2004 and 2006 (average prevalence, 11.3 vs. 2.0%). Only 27.2% of PCR-positive (but 73.3% of slide-positive) individuals had symptoms when enrolled, indicating that asymptomatic carriage of low-grade parasitaemias is a common phenomenon in frontier settlements. A circular cluster comprising 22.3% of the households, all situated in the area of most recent occupation, comprised 69.1% of all malaria infections diagnosed during the follow-up, with malaria incidence decreasing exponentially with distance from the cluster centre. By targeting one-quarter of the households, with selective indoor spraying or other house-protection measures, malaria incidence could be reduced by more than two-thirds in this community. (C) 2010 Royal Society of Tropical Medicine and Hygiene. Published by Elsevier Ltd. All rights reserved.

The Aedes aegypti larval transcriptome: a comparative perspective with emphasis on trypsins and the domain structure of peritrophins

The genome sequence of Aedes aegypti was recently reported. A significant amount of Expressed Sequence Tags (ESTs) were sequenced to aid in the gene prediction process. In the present work we describe an integrated analysis of the genomic and EST data, focusing on genes with preferential expression in larvae (LG), adults (AG) and in both stages (SG). A total of 913 genes (5.4% of the transcript complement) are LG, including ion transporters and cuticle proteins that are important for ion homeostasis and defense. From a starting set of 245 genes encoding the trypsin domain, we identified 66 putative LG, AG, and SG trypsins by manual curation. Phylogenetic analyses showed that AG trypsins are divergent from their larval counterparts (LG), grouping with blood-induced trypsins from Anopheles gambiae and Simulium vittatum. These results support the hypothesis that blood-feeding arose only once, in the ancestral Culicomorpha. Peritrophins are proteins that interlock chitin fibrils to form the peritrophic membrane (PM) that compartmentalizes the food in the midgut. These proteins are recognized by having chitin-binding domains with 6 conserved Cys and may also present mucin-like domains (regions expected to be highly O-glycosylated). PM may be formed by a ring of cells (type 2, seen in Ae. aegypti larvae and Drosophila melanogaster) or by most midgut cells (type 1, found in Ae. aegypti adult and Tribolium castaneum). LG and D. melanogaster peritrophins have more complex domain structures than AG and T. castaneum peritrophins. Furthermore, mucin-like domains of peritrophins from T. castaneum (feeding on rough food) are lengthier than those of adult Ae. aegypti (blood-feeding). This suggests, for the first time, that type 1 and type 2 PM may have variable molecular architectures determined by different peritrophins and/or ancillary proteins, which may be partly modulated by diet.