Tubulin evolution in insects: gene duplication and subfunctionalization provide specialized isoforms in a functionally constrained gene family

<p>Abstract</p> <p>Background</p> <p>The completion of 19 insect genome sequencing projects spanning six insect orders provides the opportunity to investigate the evolution of important gene families, here tubulins. Tubulins are a family of eukaryotic structural genes that form microtubules, fundamental components of the cytoskeleton that mediate cell division, shape, motility, and intracellular trafficking. Previous <it>in vivo </it>studies in <it>Drosophila </it>find a stringent relationship between tubulin structure and function; small, biochemically similar changes in the major alpha 1 or testis-specific beta 2 tubulin protein render each unable to generate a motile spermtail axoneme. This has evolutionary implications, not a single non-synonymous substitution is found in <it>beta 2 </it>among 17 species of <it>Drosophila </it>and <it>Hirtodrosophila </it>flies spanning 60 Myr of evolution. This raises an important question, How do tubulins evolve while maintaining their function? To answer, we use molecular evolutionary analyses to characterize the evolution of insect tubulins.</p> <p>Results</p> <p>Sixty-six alpha tubulins and eighty-six beta tubulin gene copies were retrieved and subjected to molecular evolutionary analyses. Four ancient clades of alpha and beta tubulins are found in insects, a major isoform clade (<it>alpha 1, beta 1</it>) and three minor, tissue-specific clades (<it>alpha 2-4, beta 2-4</it>). Based on a <it>Homarus americanus </it>(lobster) outgroup, these were generated through gene duplication events on major beta and alpha tubulin ancestors, followed by subfunctionalization in expression domain. Strong purifying selection acts on all tubulins, yet maximum pairwise amino acid distances between tubulin paralogs are large (0.464 substitutions/site beta tubulins, 0.707 alpha tubulins). Conversely orthologs, with the exception of reproductive tissue isoforms, show little sequence variation except in the last 15 carboxy terminus tail (CTT) residues, which serve as sites for post-translational modifications (PTMs) and interactions with microtubule-associated proteins. CTT residues overwhelming comprise the co-evolving residues between <it>Drosophila </it>alpha 2 and beta 3 tubulin proteins, indicating CTT specializations can be mediated at the level of the tubulin dimer. Gene duplications post-dating separation of the insect orders are unevenly distributed, most often appearing in major <it>alpha 1 </it>and minor <it>beta 2 </it>clades. More than 40 introns are found in tubulins. Their distribution among tubulins reveals that insertion and deletion events are common, surprising given their potential for disrupting tubulin coding sequence. Compensatory evolution is found in <it>Drosophila beta 2 </it>tubulin cis-regulation, and reveals selective pressures acting to maintain testis expression without the use of previously identified testis cis-regulatory elements.</p> <p>Conclusion</p> <p>Tubulins have stringent structure/function relationships, indicated by strong purifying selection, the loss of many gene duplication products, alpha-beta co-evolution in the tubulin dimer, and compensatory evolution in <it>beta 2 </it>tubulin cis-regulation. They evolve through gene duplication, subfunctionalization in expression domain and divergence of duplication products, largely in CTT residues that mediate interactions with other proteins. This has resulted in the tissue-specific minor insect isoforms, and in particular the highly diverse <it>α3</it>, <it>α4</it>, and <it>β2 </it>reproductive tissue-specific tubulin isoforms, illustrating that even a highly conserved protein family can participate in the adaptive process and respond to sexual selection.</p

The Effectiveness of a Model of Language-Focused Classroom Instruction on the Vocabulary and Narrative Development of Kindergarten Children

This is the publisher's version, also available at http://ehis.ebscohost.com/ehost/detail?sid=3c1386ac-4367-4308-aec6-0505e48d6c28%40sessionmgr15&vid=3&hid=8&bdata=JnNpdGU9ZWhvc3QtbGl2ZQ%3d%3d#db=a9h&AN=85920663The purpose of the study that is reported in this article was to examine the effectiveness of a model of language-focused instruction, dehvered by the classroom teacher, on the vocabulary and narrative development of kindergarten children hving in high-poverty conditions. There were 22 participants, the majority significantly behind their peers on standardized measures of vocabulary and narrative (understanding and production). The four-day sequence of instruction focused on a different storybook each week for 12 weeks. The findings demonstrated that it was possible to increase both vocabulary and narrative with exphcit classroom instruction, repeated experiences, and active engagement. Implications for core kindergarten instruction and for teacher education are discussed

Språk, mennesker og makt i Metodistkirken. En kritisk diskursanalyse av metodistmenighetenes årsmeldinger fra 2017

Menneskesyn dreier seg om mer enn flotte ord verdidokumenter. Menneskesyn kommer til utrykk gjennom holdninger og handlinger, og disse holdningene og handlingene bæres av mennesker. Denne masteravhandlingen omhandler hvordan forskjeller mellom menneskesynet som fremkommer i verdidokumenter kan skille seg fra menneskesynet som kommer til utrykk i det virkelige liv. Ved hjelp av sosialkonstruktivismens idé om at språk skaper forståelse, og metoden kritisk diskursanalyse, søker oppgaven å svare på problemstillingen: «Hvilket menneskesyn som kommer til utrykk i metodistmenighetenes årsmeldinger fra 2017, og hvordan samsvarer dette med det menneskesyn De Sosiale Prinsipper sier at Metodistkirken har?» Oppgaven presenterer en analyse av norske metodistmenigheters årsmeldinger, med fokus på hvordan man omtaler kjønn, etnisitet og alder, og setter dette opp mot verdidokumentet de Sosiale Prinsipper, som omhandler hva Metodistkirkens offisielle syn er. Analysens formål er å påpeke de områder der årsmeldingene skiller seg fra de holdningene de Sosiale Prinsipper presenterer. Ettersom oppgaven fokuserer på svært mange årsmeldinger, mange menigheter, og mange årsmeldingsforfattere fra forskjellige bakgrunner, gir dette en bredde i materialet som kan gi en pekepinn på hvordan det faktisk er i Metodistkirken, og hvor man har behov for å sette inn tiltak for å sørge for at praksis samsvarer med ønskede verdier. Denne oppgaven har som formål å aktualisere disse sprikene hvor teori og praksis ikke samsvarer, i håp om å være et ledd i at disse sprikene kan tettes

Barnfri - En kvalitativ innehållsanalys av kvinnors berättelser om att leva utan barn

The aim of this study is to utilize a qualitative content analysis in order to examine the stories of twelve childfree women featured in the anthology "Nobody's Mother" [translated title] (2013). When designing this study we have focused on the reasons to why these women have chosen not to have any children and how they experience social expectations related to motherhood. Swedish welfare policy is designed to benefit families with children and is thus inherently pronatalistic, resulting in a strong connection between public policy, family and reproduction. The coding process highlighted several salient themes which were then analyzed according to Hirdman´s gender system and Goffman´s theory of stigma. The women testify that the environment stands adverse to their choice and that they experience themselves as being deviated from the norm. This can according Goffman´s theory be seen as stigmatization of childfree women in today´s society. Hirdmans gender system visualized the gendered stereotypes in the women’s stories regarding their motives to be childfree. It also visualized their experiences of the pronatalistic norm, which show that women and motherhood are strongly interconnected

Copepod life strategy and population viability in response to prey timing and temperature : testing a new model across latitude, time, and the size spectrum

A new model ("Coltrane": Copepod Life-history Traits and Adaptation to Novel Environments) describes environmental controls on copepod populations via (1) phenology and life history and (2) temperature and energy budgets in a unified framework. The model tracks a cohort of copepods spawned on a given date using a set of coupled equations for structural and reserve biomass, developmental stage, and survivorship, similar to many other individual-based models. It then analyzes a family of cases varying spawning date over the year to produce population-level results, and families of cases varying one or more traits to produce community-level results. In an idealized global-scale testbed, the model correctly predicts life strategies in large Calanus spp. ranging from multiple generations per year to multiple years per generation. In a Bering Sea testbed, the model replicates the dramatic variability in the abundance of Calanus glacialis/marshallae observed between warm and cold years of the 2000s, and indicates that prey phenology linked to sea ice is a more important driver than temperature per se. In a Disko Bay, West Greenland testbed, the model predicts the viability of a spectrum of large-copepod strategies from income breeders with a adult size ~100 μgC reproducing once per year through capital breeders with an adult size > 1000 μgC with a multiple-year life cycle. This spectrum corresponds closely to the observed life histories and physiology of local populations of Calanus finmarchicus, C. glacialis, and Calanus hyperboreus. Together, these complementary initial experiments demonstrate that many patterns in copepod community composition and productivity can be predicted from only a few key constraints on the individual energy budget: the total energy available in a given environment per year; the energy and time required to build an adult body; the metabolic and predation penalties for taking too long to reproduce; and the size and temperature dependence of the vital rates involved