scholarly journals Effective purifying selection in ancient asexual oribatid mites

2017 ◽  
Author(s):  
Alexander Brandt ◽  
Ina Schaefer ◽  
Julien Glanz ◽  
Tanja Schwander ◽  
Mark Maraun ◽  
...  
Keyword(s):  
Deleterious Mutation ◽  
Oribatid Mite ◽  
Purifying Selection ◽  
Oribatid Mites ◽  
Transcriptome Data ◽  
Ancient Asexual ◽  
Large Populations ◽  
Per Se ◽  
Mutational Meltdown

AbstractSex is beneficial in the long-term, because it can prevent mutational meltdown through increased effectiveness of selection. This idea is supported by empirical evidence of deleterious mutation accumulation in species with a recent transition to asexuality. Here, we studied the effectiveness of purifying selection in oribatid mites, which have lost sex millions of years ago and diversified into different families and species while reproducing asexually. We compared the accumulation of deleterious coding and non-coding mutations between three asexual and three sexual lineages using transcriptome data. Contrasting studies of young asexual lineages, we find evidence for strong purifying selection that is more effective in asexual compared to sexual oribatid mite lineages. Our results suggest that large populations likely sustain effective purifying selection and facilitate the escape of mutational meltdown in the absence of sex. Thus, sexper seis not a prerequisite for the long-term persistence of animal lineages.

scholarly journals Effective purifying selection in ancient asexual oribatid mites

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Alexander Brandt ◽  
Ina Schaefer ◽  
Julien Glanz ◽  
Tanja Schwander ◽  
Mark Maraun ◽  
...  
Keyword(s):  
Purifying Selection ◽  
Oribatid Mites ◽  
Ancient Asexual

Erratum

PEDIATRICS ◽  
1989 ◽  
Vol 84 (4) ◽  
pp. 612-612
Keyword(s):  
Ultraviolet Light ◽  
Skin Color ◽  
Social Norm ◽  
Sun Exposure ◽  
Sun Protection ◽  
Social Perceptions ◽  
Increased Risk ◽  
Ineffective Efforts ◽  
Per Se

In the commentary, "Sunburns, Melanoma, and the Pediatrician," by Williams and Sagebiel (Pediatrics 1989;84:381-382), three lines were omitted from the bottom of p 381. The whole paragraph is reprinted here. It is clear that a change is required in social perceptions in which a suntan is equated with health and beauty—not because suntans per se are unhealthy (the deleterious effects of ultraviolet light at suberythemogenic levels are not wellestablished), but because the persistent and often futile efforts of those who constitutionally have less pigment to achieve a tan have serious long-term health consequences. Ideally, there should be a social norm of beauty in which the natural differences in skin color are appreciated and black, tan, pink, and all shades in between are celebrated. Similarly, we need to change our thinking about freckles and solar lentigines. These are not "cute" but represent the ineffective efforts of melanocytes in genetically underpigmented skin to provide protective pigmentation in response to solar stress. Although pediatricians alone cannot change social concepts of beauty, we can instruct our patients and their families about sun protection and we can monitor them for early signs of excessive sun exposure. Weinstock et al demonstrated an increased risk of melanoma for those who had blistering sunburns in adolescence. Although they did not address the risk associated with sunburning prior to ages 15 years, it seems likely that these data can be applied to children of all ages. Therefore, instruction and sun protection should begin in infancy. Moreover, teenagers are known to be both highly conditioned by peer concepts of beauty and relatively impervious to the counsel of their elders. It is essential, therefore, that they enter these years with skin that has been well protected and with minds well indoctrinated.

scholarly journals Diversity and evolution of surface polysaccharide synthesis loci in Enterobacteriales

2019 ◽  
Author(s):  
Kathryn E. Holt ◽  
Florent Lassalle ◽  
Kelly L. Wyres ◽  
Ryan Wick ◽  
Rafal J. Mostowy
Keyword(s):  
Evolutionary Dynamics ◽  
Bacterial Species ◽  
Purifying Selection ◽  
Evolutionary Forces ◽  
Polysaccharide Synthesis ◽  
Surface Polysaccharides ◽  
Surface Polysaccharide ◽  
Selective Preservation ◽  
Multiple Species

Bacterial capsules and lipopolysaccharides are diverse surface polysaccharides (SPs) that serve as the frontline for interactions with the outside world. While SPs can evolve rapidly, their diversity and evolutionary dynamics across different taxonomic scales has not been investigated in detail. Here, we focused on the bacterial order Enterobacteriales (including the medically-relevant Enterobacteriaceae), to carry out comparative genomics of two SP locus synthesis regions, cps and kps, using 27,334 genomes from 45 genera. We identified high-quality cps loci in 22 genera and kps in 11 genera, around 4% of which were detected in multiple species. We found SP loci to be highly dynamic genetic entities: their evolution was driven by high rates of horizontal gene transfer (HGT), both of whole loci and component genes, and relaxed purifying selection, yielding large repertoires of SP diversity. In spite of that, we found the presence of (near-)identical locus structures in distant taxonomic backgrounds that could not be explained by recent exchange, pointing to long-term selective preservation of locus structures in some populations. Our results reveal differences in evolutionary dynamics driving SP diversity within different bacterial species, with lineages of Escherichia coli, Enterobacter hormachei and Klebsiella aerogenes most likely to share SP loci via recent exchange; and lineages of Salmonella enterica, Citrobacter sakazakii and Serratia marcescens most likely to share SP loci via other mechanisms such as long-term preservation. Overall, the evolution of SP loci in Enterobacteriales is driven by a range of evolutionary forces and their dynamics and relative importance varies between different species.

CYBB, an NADPH-oxidase gene: restricted diversity in humans and evidence for differential long-term purifying selection on transmembrane and cytosolic domains

2008 ◽  
Vol 29 (5) ◽  
pp. 623-632 ◽  
Author(s):  
Eduardo Tarazona-Santos ◽  
Toralf Bernig ◽  
Laurie Burdett ◽  
Wagner C.S. Magalhaes ◽  
Cristina Fabbri ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Purifying Selection ◽  
Oxidase Gene ◽  
Cytosolic Domains

Oribatid mites (Acari, Oribatida) from Tam Dao National Park (Northern Vietnam), with description of two new species

2018 ◽  
Vol 23 (2) ◽  
pp. 314 ◽  
Author(s):  
Sergey G. Ermilov ◽  
Josef Stary
Keyword(s):  
New Species ◽  
Body Size ◽  
National Park ◽  
Oribatid Mite ◽  
Oribatid Mites ◽  
Oriental Region ◽  
Northern Vietnam ◽  
Two New Species ◽  
Tam Dao National Park ◽  
First Time

The present study is based on oribatid mite material (Acari, Oribatida) collected from Tam Dao National Park (Northern Vietnam) in 1988. A list of identified taxa, including 119 species from 80 genera and 47 families, is presented; of these, 13 species (Epilohmannoides rabori, Camisia spinifer, Sadocepheus undulatus, Eremobelba flexuosa, Hammerella excisa, Suctobelbella inenodabilis, Dolicheremaeus auritus, Eupelops acromios, Protoribates genitalis, Allogalumna machadoi, Carinogalumna philippinensis, Pergalumna magnipora capillaris, Galumnella nipponica) and five genera (Epilohmannoides, Camisia, Sadocepheus, Brassiella, Carinogalumna) are recorded in the Vietnamese fauna for the first time, and two species (Tokunocepheus mizusawai, Flagellozetes (Cosmogalumna) ornatus), one genus (Tokunocepheus) and one family (Tokunocepheidae) are recorded in the Oriental region for the first time. Two new species are described: Ramusella paraarcuata sp. nov. differs from Ramusella arcuata Mahunka & Mahunka-Papp, 2012 by the larger body size, lamellar setae similar in length and thickness to interlamellar setae, the presence of two or three branches on bothridial setae, and the absence of notogastral setae c. Neoribates paragracilis sp. nov. differs from Neoribates gracilis Travé, 1972 by the larger body size, and the presence of long apex (not shorter than head) on bothridial setae.

New and interesting oribatid mites (Acari, Oribatida) from Hanoi (Northern Vietnam)

2018 ◽  
Vol 23 (1) ◽  
pp. 61 ◽  
Author(s):  
Sergey G. Ermilov ◽  
Josef Stary
Keyword(s):  
New Species ◽  
Body Surface ◽  
Oribatid Mite ◽  
Oribatid Mites ◽  
Oriental Region ◽  
Northern Vietnam ◽  
Two New Species ◽  
First Time ◽  
The City

The present study is based on oribatid mite material (Acari, Oribatida) collected from the city of Hanoi in Northern Vietnam. A list of identified taxa, including 68 species from 49 genera and 32 families, is presented; of these, ten species (Trhypochthonius japonicus, Nothrus oblongus, Hermanniella aliverdievae, Arthrodamaeus decemsetiger, Arcoppia fenestralis orientalis, Ramusella puertomonttensis, Allosuctobelba grandis, Scheloribates elegans, Neoribates gracilis, Pergalumna corniculata) and one genus (Trhypochthonius) are recorded in the Vietnamese fauna for the first time; seven species (Xenillus selgae, Arcoppia curtipila, Cycloppia granulata, Hammerella gracilis, Allosuctobelba tricuspidata, Ceratozetoides maximus, Protoribates hakonensis) and one genus (Ceratozetoides) are recorded in the Oriental region for the first time. Two new species belonging to the genera Allosuctobelba and Oribatella are described: Allosuctobelba alexanderkhaustovi sp. nov. differs from Allosuctobelba tricuspidata tricuspidata Aoki, 1984 in the rostrum having three to four lateral teeth and very long notogastral setae positioned in two parallel rows; Oribatella pavelklimovi sp. nov. differs from Oribatella kunsti Bernini, 1972 by the granulate body surface, setiform  aggenital setae and the dorsolateral position of notogastral setae lm and lp.

Incompatible Images

2009 ◽  
pp. 186-200 ◽  
Author(s):  
Michel J. Sassene
Keyword(s):  
Health System ◽  
Health Systems ◽  
Clinical Evidence ◽  
Asthma Management ◽  
Self Management ◽  
Management Systems ◽  
Use Of Self ◽  
Per Se

This chapter investigates asthmatics’ reasons for not adopting an e-health system for asthma selfmanagement. An understanding of these reasons is particularly relevant, because clinical evidence indicates that, if used, such systems lead to better asthma management. The investigated asthma system is, however, based on a taken-for-granted image of asthmatics as, per se, striving to be symptom-free. This image is incompatible with interviewed asthmatics’ day-to-day performances of their asthma, and renders invisible (a) that their asthma performances emphasize an economy of good passages and of feeling capable, (b) that they achieve the objective of feeling capable in quite different ways, and (c) that feeling capable does not per se equal being symptom-free all the time. To attain long-term use of self-management systems and other patient-centred e-health systems, such systems must acknowledge and link into the manifold performances that comprise users’ ways of living with their disease.

scholarly journals Long-term experimental evolution reveals purifying selection on piRNA-mediated control of transposable element expression

BMC Biology ◽  
2020 ◽  
Vol 18 (1) ◽  
Author(s):  
Ulfar Bergthorsson ◽  
Caroline J. Sheeba ◽  
Anke Konrad ◽  
Tony Belicard ◽  
Toni Beltran ◽  
...  
Keyword(s):  
Natural Selection ◽  
Transcriptional Activation ◽  
Small Rnas ◽  
Active Regions ◽  
Purifying Selection ◽  
Ancestral Population ◽  
Sequence Context ◽  
C Elegans ◽  
Population Sizes

Abstract Background Transposable elements (TEs) are an almost universal constituent of eukaryotic genomes. In animals, Piwi-interacting small RNAs (piRNAs) and repressive chromatin often play crucial roles in preventing TE transcription and thus restricting TE activity. Nevertheless, TE content varies widely across eukaryotes and the dynamics of TE activity and TE silencing across evolutionary time is poorly understood. Results Here, we used experimentally evolved populations of C. elegans to study the dynamics of TE expression over 409 generations. The experimental populations were evolved at population sizes of 1, 10 and 100 individuals to manipulate the efficiency of natural selection versus genetic drift. We demonstrate increased TE expression relative to the ancestral population, with the largest increases occurring in the smallest populations. We show that the transcriptional activation of TEs within active regions of the genome is associated with failure of piRNA-mediated silencing, whilst desilenced TEs in repressed chromatin domains retain small RNAs. Additionally, we find that the sequence context of the surrounding region influences the propensity of TEs to lose silencing through failure of small RNA-mediated silencing. Conclusions Our results show that natural selection in C. elegans is responsible for maintaining low levels of TE expression, and provide new insights into the epigenomic features responsible.

Oribatid mites of the family Astegistidae (Acari: Oribatida) in Mongolia

Zootaxa ◽  
2007 ◽  
Vol 1472 (1) ◽  
pp. 55
Author(s):  
BADAMDORJ BAYARTOGTOKH
Keyword(s):  
New Species ◽  
Oribatid Mite ◽  
Oribatid Mites ◽  
The Family ◽  
Northern Mongolia ◽  
Cool Temperate ◽  
Distribution And Ecology ◽  
First Time ◽  
A New Species ◽  
Mite Family

The oribatid mite family Astegistidae is represented in Mongolia by four species in two genera. A new species, Cultroribula taigagica sp. nov., collected from cool temperate forests in Northern Mongolia is described based on adults. In addition, three known species, Astegistes pilosus (C.L. Koch, 1840), Cultroribula dentata Willmann, 1950 and Cultroribula vtorovi Krivolutsly, 1971 are recorded for the first time from Mongolia, which are redescribed along with data on their distribution and ecology. A key to Mongolian species of Astegistidae is given.

scholarly journals Oribatid mites (Acari, Oribatida) of bushy patches in steppe vegetation of cape Tarkhankut in Crimea (Ukraine)

2011 ◽  
Vol 48 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Stanisław Seniczak ◽  
Sławomir Kaczmarek ◽  
Anna Seniczak
Keyword(s):  
Age Structure ◽  
Vegetation Type ◽  
Oribatid Mite ◽  
Oribatid Mites ◽  
Species Number ◽  
Steppe Vegetation ◽  
Mite Communities

Oribatid mites (Acari, Oribatida) of bushy patches in steppe vegetation of cape Tarkhankut in Crimea (Ukraine)The density, species number, and age structure of oribatid mites were investigated in bushy patches (elm, hawthorn, hawthorn with rose) in steppe vegetation of cape Tarkhankut (Crimea). In these patches, the density of mites in shrub litter, herbs and moss was higher, but species number was similar like in open steppe vegetation. Hawthorn increased the density distinctly more than hawthorn with rose or bushy elms. In bushy patches, the samples of moss were richer in mites than samples of shrub litter alone or with herbs. Among oribatid mites,Chamobatesc.f.spinosusandTrhypochthonius tectorumwere most abundant, but relatively abundant and common were alsoTectocepheus velatus, Oribatulasp. 1,Achipteria nitens, andBrachychthonius berlesei. In oribatid mite communities, adults dominated, but the age structure of populations greatly depended on vegetation type.

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