375 research outputs found

    A complex of the blood fluke genus Psettarium (Digenea: Aporocotylidae) infecting tetraodontiform fishes of east Queensland waters

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    Seven species of Psettarium (Digenea: Aporocotylidae), including four new species, are reported from tetraodontiform fishes from off coastal east Queensland. Psettarium pandora n. sp. infects the yellow boxfish, Ostracion cubicus (Ostraciidae), the first known aporocotylid to infect this family of fishes. Three new species are reported from pufferfishes of the genus Arothron (Tetraodontidae): Psettarium yoshidai n. sp. infects the map puffer (Arothron mappa), Psettarium hustoni n. sp. infects the black-spotted puffer (A. nigropunctatus) and Psettarium martini n. sp. infects the starry puffer (A. stellatus). We also report three species of Psettarium from Australian waters for the first time. Paracardicola hawaiensis Martin, 1960, the sole species of Paracardicola, is redescribed based on specimens collected from the type-host, the stars-and-stripes puffer, Arothron hispidus. Paracardicola is synonymised with Psettarium and P. hawaiensis is recombined as Psettarium hawaiiense (Martin, 1960) n. comb. Psettarium pulchellum Yong, Cutmore, Bray, Miller, Semarariana, Palm & Cribb, 2016, described from the narrow-lined puffer (Arothron manilensis) from off Bali, Indonesia, is reported from the same fish species at two locations on the Queensland coast, significantly extending the range of this species. Psettarium nolani (Bray, Cribb & Littlewood, 2013), originally described from French Polynesia, is reported from A. hispidus, A. manilensis and A. stellatus, representing both new host and locality records for this species. Molecular phylogenetic analysis shows these species to all be closely related, such that they cannot be considered to represent separate genera despite their differing morphology. Analysis of 28S sequence data for Psettarium anthicum Bullard & Overstreet, 2006, a non-tetraodontiform-infecting species, shows it to be distantly related to all other species of Psettarium for which sequence data are available. The species is re-assigned to a new genus, Cardallagium n. gen., as Cardallagium anthicum (Bullard & Overstreet, 2006) n. comb. We think it likely that the host range of species of Psettarium is limited to tetraodontiform fishes. We assessed the infection biology of two species, P. nolani and P. hawaiiense n. comb. infecting A. hispidus, using histology to assess the pathways of egg release for these species. Eggs of both species were observed in both circulatory and visceral organs of infected hosts, often in high numbers. Eggs were seen trapped in the mucosal layer of the intestine and, in rare instances, causing lesions in the laminar epithelium, providing the strongest evidence yet that they pass through the gut wall and escape the host via the faeces. Lastly, we discuss the biogeographical implications of our findings, noting that some Psettarium species now show very wide geographical distributions

    Complete mitochondrial genomes and nuclear ribosomal RNA operons of two species of Diplostomum (Platyhelminthes: Trematoda): a molecular resource for taxonomy and molecular epidemiology of important fish pathogens

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    © 2015 Brabec et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. The attached file is the published version of the article

    Nematode endoparasites do not codiversify with their stick insect hosts.

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    Host-parasite coevolution stems from reciprocal selection on host resistance and parasite infectivity, and can generate some of the strongest selective pressures known in nature. It is widely seen as a major driver of diversification, the most extreme case being parallel speciation in hosts and their associated parasites. Here, we report on endoparasitic nematodes, most likely members of the mermithid family, infecting different Timema stick insect species throughout California. The nematodes develop in the hemolymph of their insect host and kill it upon emergence, completely impeding host reproduction. Given the direct exposure of the endoparasites to the host's immune system in the hemolymph, and the consequences of infection on host fitness, we predicted that divergence among hosts may drive parallel divergence in the endoparasites. Our phylogenetic analyses suggested the presence of two differentiated endoparasite lineages. However, independently of whether the two lineages were considered separately or jointly, we found a complete lack of codivergence between the endoparasitic nematodes and their hosts in spite of extensive genetic variation among hosts and among parasites. Instead, there was strong isolation by distance among the endoparasitic nematodes, indicating that geography plays a more important role than host-related adaptations in driving parasite diversification in this system. The accumulating evidence for lack of codiversification between parasites and their hosts at macroevolutionary scales contrasts with the overwhelming evidence for coevolution within populations, and calls for studies linking micro- versus macroevolutionary dynamics in host-parasite interactions

    Lives on track? Long-term earnings returns to selective school placement in England and Denmark

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    We explore the influence of between-school ability placement at lower secondary education on earnings across the life course in England and Denmark. We go beyond the mid-career snapshot provided by previous studies by exploiting the availability of four decades worth of earnings data for individuals born in the mid-1950s. Members of this cohort who were judged to be among the most academically able attended grammar schools in England (19 percent) and advanced secondary schools (Realskole) in Denmark (51 percent) prior to the start of comprehensivisation. This key difference makes England and Denmark interesting cases for comparison, not least since pro-selection policies have re-emerged in England based on the claim that grammar schools lead to better educational and labour market outcomes. Our analysis of the influence of selective school placement on earnings finds little support for this contention. We find that those from socioeconomically disadvantaged backgrounds were strikingly under-represented in schools ear-marked for higher ability pupils in both countries, even after taking into account social class differences in measured ability. Our analysis for England finds only modest earnings returns to attending a grammar school, totalling just £39,000 across the life course, while in Denmark the lifetime earnings returns to attending Realskole are somewhat larger (£194,000). Because those from advantaged backgrounds were substantially over-represented at grammar schools and Realskoles, these returns accrue disproportionately to pupils from more advantaged backgrounds. Lower secondary school placement in Denmark accounts for forty percent of the intergenerational reproduction of socioeconomic advantage and disadvantage, more than half of which is due to selection into school types based on socioeconomic background rather than measured ability. Our findings question the wisdom of expanding grammar schools when they appear to do little to improve individuals’ earnings or increase social mobility

    Social patterning in grip strength and in its association with age; A cross sectional analysis using the UK Household Longitudinal Study (UKHLS)

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    Background: Grip strength in early adulthood and midlife is an important predictor of disability, morbidity and mortality in later life. Understanding social patterning in grip strength at different life stages could improve insight into inequalities in age-related decline and when in the life course interventions could prevent the emergence of inequalities. Methods: Using United Kingdom Household Longitudinal Study (UKHLS) data on 19,292 people aged 16 to 99, fractional polynomial models were fitted to identify which function of age best described its association with grip strength. Linear regressions were used to establish whether socio-economic position (SEP), as measured by maternal education, highest educational qualification and income, was associated with grip strength. To test whether the association between age and grip strength was modified by SEP, interactions between SEP and the age terms were added. Differentiation was used to identify the age at which grip strength was highest for men and women and predicted levels of grip strength at peak were compared. Results: SEP is significantly associated with grip strength on all SEP measures, except education for men. Grip strength is highest at a younger age, and less strong for all measures of disadvantage for women and most measures for men. Interaction terms were not statistically significant indicating that the association between age and grip strength was not modified by SEP. Grip strength peak was 29.3 kg at age 33 for women with disadvantaged childhood SEP compared with 30.2 kg at age 35 for women with advantaged childhood SEP. Conclusion: The SEP differences in age and level of peak grip strength could be indicative of decline in muscle strength beginning earlier and from a lower base for disadvantaged groups. This could impact on the capacity for healthy ageing for those with disadvantaged SEP

    Molecular approaches to trematode systematics: 'best practice' and implications for future study

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    To date, morphological analysis has been the cornerstone to trematode systematics. However, since the late-1980s we have seen an increased integration of genetic data to overcome problems encountered when morphological data are considered in isolation. Here, we provide advice regarding the ‘best molecular practice’ for trematode taxonomy and systematic studies, in an attempt to help unify the field and provide a solid foundation to underpin future work. Emphasis is placed on defining the study goals and recommendations are made regarding sample preservation, extraction methods, and the submission of molecular vouchers. We advocate generating sequence data from all parasite species/host species/geographic location combinations and stress the importance of selecting two independently evolving loci (one ribosomal and one mitochondrial marker). We recommend that loci should be chosen to provide genetic variation suitable to address the question at hand and for which sufficient ‘useful’ comparative sequence data already exist. Quality control of the molecular data via using proof-reading Taq polymerase, sequencing PCR amplicons using both forward and reverse primers, ensuring that a minimum of 85% overlap exists when constructing consensus sequences, and checking electropherograms by eye is stressed. We advise that all genetic results are best interpreted using a holistic biological approach, which considers morphology, host identity, collection locality, and ecology. Finally, we consider what advances next-generation sequencing holds for trematode taxonomy and systematics

    Linking the sectoral employment structure and household poverty in the United Kingdom

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    Structural changes in the labour markets of developed economies, and changes in their institutional characteristics, have led to growing unease about the nature of low-paid employment. Related concerns have been expressed about the persistence of low-pay, the fragmentation of work and the growth of under-employment. While all these factors have potential implications for individuals’ earnings, less is known about the connection between labour market change, patterns of sectoral growth and decline and household poverty outcomes. This article shows distinct patterns of poverty outcomes by sector of employment, after controlling for other factors. However, household characteristics, in particular the presence of a second earner, do strongly mitigate the poverty risk. Overall, the findings demonstrate that policymakers need to develop a coherent policy towards poverty that recognises the nature of jobs growth and the distribution of ‘good jobs’ across households

    How Many Species Are There on Earth and in the Ocean?

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    The diversity of life is one of the most striking aspects of our planet; hence knowing how many species inhabit Earth is among the most fundamental questions in science. Yet the answer to this question remains enigmatic, as efforts to sample the world's biodiversity to date have been limited and thus have precluded direct quantification of global species richness, and because indirect estimates rely on assumptions that have proven highly controversial. Here we show that the higher taxonomic classification of species (i.e., the assignment of species to phylum, class, order, family, and genus) follows a consistent and predictable pattern from which the total number of species in a taxonomic group can be estimated. This approach was validated against well-known taxa, and when applied to all domains of life, it predicts ∼8.7 million (±1.3 million SE) eukaryotic species globally, of which ∼2.2 million (±0.18 million SE) are marine. In spite of 250 years of taxonomic classification and over 1.2 million species already catalogued in a central database, our results suggest that some 86% of existing species on Earth and 91% of species in the ocean still await description. Renewed interest in further exploration and taxonomy is required if this significant gap in our knowledge of life on Earth is to be closed

    The motivation for citizens’ involvement in life sciences research is predicted by age and gender

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    Open Science is an umbrella term encompassing multiple concepts as open access to publications, open data, open education and citizen science that aim to make science more open and transparent. Citizen science, an important facet of Open Science, actively involves nonscientists in the research process, and can potentially be beneficial for multiple actors, such as scientists, citizens, policymakers and society in general. However, the reasons that motivate different segments of the public to participate in research are still understudied. Therefore, based on data gathered from a survey conducted in Czechia, Germany, Italy, Spain, Sweden, and the UK (N = 5,870), this study explores five types of incentives that can motivate individuals to become involved in life sciences research. The results demonstrate that men and younger individuals are more persuaded by extrinsic motives (external benefits or rewards), as compared with women and older people, who are driven by intrinsic motives (that originates from within an individual). This paper shows that specific strata of the population are differentially motivated to engage in research, thereby providing relevant knowledge for effectively designing public involvement activities that target various groups of the public in research projects
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