748 research outputs found
Sad-Loser Lottery
No full textWe consider lotteries with reimbursements. It turns out that without loss of generality it is enough analyze lotteries where the winner gets her expenses reimbursed. We find that such a lottery (Sad-Loser) has multiple pure-strategy equilibria. We describe all equilibria and discuss their properties. In particular, we find (1) a sufficient condition for the net total spending to be higher in the Sad-Loser lottery than in the standard lottery, (2) that the Exclusion Principle holds.
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Identifying a common cause of the loser cell status in Drosophila melanogaster.
No full textCell competition is the process whereby less fit cells termed “losers” are selectively eliminated from a tissue by their fitter neighbors – or “ winners.” This sacrifice of aberrant cells is thought to have evolved at the advent of multicellularity to enforce cell co-operativity and ensure the fitness of the host organism. Accumulating evidence over the last 40 years has suggested key roles for cell competition during development, adult tissue homeostasis and at the onset and during the progression of diseases including cancer. However, if we are to exploit competition in the treatment of human pathologies and in tissue regeneration, we still have a lot to learn about the underlying mechanisms that ultimately instruct the elimination of loser cells.
The main goal of this work was to identify the key molecular events that are responsible for initiating the loser status of Minute heterozygous cells. As many Minute mutations affect ribosomal genes, it has long been assumed that the loser status is closely linked to their associated slow growth phenotype, which occurs a consequence of reduced protein synthesis. Surprisingly, I have found that the loser status is independent of rates of translation. Instead, the activity of a single transcription factor, Nrf2, that typically co-ordinates an oxidative stress response, is sufficient to instruct the elimination of cells by their neighbors. Given the importance of Nrf2, I have sought to identify events occurring both upstream and downstream of the pathway in the loser context. Here, I have shown how multiple loser cell types are suffering from an underlying proteotoxic stress, as a result of an imbalance in proteostasis and their accumulation of toxic protein aggregates. In addition, I have developed a screening strategy to identify key molecules downstream of Nrf2 that could be involved in loser cell recognition. These findings not only provide new insights into the mechanisms of cell competition, but broaden the implications of the process to age-related diseases including those that result in neurodegeneration
Heterozygosity at Gr64 loci exacerbates competitive <i>RpS3</i><sup><i>+/-</i></sup> loser cell elimination.
No full text(A–G) Representative images of wing discs containing RpS3+/- loser cells (green) competing against wild-type winners (unlabelled) and stained for cleaved-Dcp1 (red). RpS3+/- clones were generated in a wild-type background (A) or in wing discs heterozygous for any one of the Gr64 genes a through f (mutations used were Gr64aGAL4, Gr64bLEXA, Gr64cLEXA, Gr64d1, Gr64eLEXA, and Gr64fLEXA) (B–G). (H) Quantification of the percentage of cells undergoing apoptosis at loser clone borders in wing discs of genotypes as shown in (A–G). Statistics reflect multiple logistic regression across 3 replicates (details provided in Materials and methods). (I) Quantification of loser cell growth in wing discs of the genotypes shown in (A–G), as measured by the percent loser clone coverage of the pouch. Statistics reflect Student t test with FDR p-correction. ncontrol = 16, nGr64aGAL4 = 15, nGr64bLEXA = 15, nGr64cLEXA = 11, nGr64d[1] = 12, nGr64eLEXA = 9, nGr64fLEXA = 8. For all quantifications, the horizontal line indicates the mean. Scale bars correspond to 50 μm. Numerical data can be found in the “Fig 2” sheet of S1 Data. FDR, false discovery rate; Gr64, Gustatory Receptor 64; Rp, ribosome protein.</p
Control Freak Loser Bitches Need Love, Too
No full textControl Freak Loser Bitches Need Love, Too is a personal essay collection examining how author Megan Williams attempts to obsessively control her own body after suffering sexual harassment and assault in her girlhood. Even a decade later, Williams grapples with the shame of being silenced due to her weight. She shrinks down one-hundred and fifty pounds in the hopes of making a body that is hers and hers alone, but finds hunger cannot heal her. Through narrative, lyric, and experimental storytelling, Williams weaves a devastating, humorous, and warm tapestry about the ways we get worse before we get better
Loser-effect duration evolves independently of fighting ability
No full textThis is the author accepted manuscript. The final version is available from Royal Society via the DOI in this record.Data supporting this paper can be found in the Dryad Digital Repository: https://doi.org/10.5061/dryad.34b1466 [67].Winning or losing contests can impact subsequent competitive behaviour and the duration of these effects can be prolonged. While it is clear effects depend on social and developmental environments, the extent to which they are heritable, and hence evolvable, is less clear and remains untested. Furthermore, theory predicts that winner and loser effects should evolve independently of actual fighting ability, but again tests of this prediction are limited. Here we used artificial selection on replicated beetle populations to show that the duration of loser effects can evolve, with a realized heritability of about 17%. We also find that naive fighting ability does not co-evolve with reductions in the duration of the loser effect. We discuss the implications of these findings and how they corroborate theoretical predictions.Japan Society for the Promotion of Scienc
Live imaging of the GSC niche following transplantation of fluorescently labeled winner and loser GSCs.
No full textGSCs from each winner and loser pair were isolated by FACS and labeled with cell tracker dyes (winner GSCs (WG, labeled green); loser GSCs (LG, labeled red)) and co-injected into a subclone of the loser genotype. 24 h later the newly developing GSC niche was imaged (A-I). The dotted white line is superimposed on the epidermis, the evagination is the newly developing zooid, and the niche is between the white line and the developing zooid viscera (see S1 Fig). Representative images of the three types of phenotypes observed in this experiment are shown (A-C; D-F; G-I), and described in detail in the text. Superimposed images of light and both fluorescent channels are shown in panels A, D, and G. J. Labeled cells were observed in ca. 70% of the GSC niches visualized, shown is the quantification of the number of winner vs loser GSCs observed (n = 9). Winner GSCs had a slight advantage versus loser GSCs (1.9X; p<0.02).</p
Proteotoxic stress is a driver of the loser status and of cell competition
No full textCell competition allows winner cells to eliminate less fit loser cells in tissues. In Minute cell competition, cells with a heterozygous mutation in ribosome genes, such as RpS3+/− cells, are eliminated by wild-type cells. How cells are primed as losers is partially understood and it has been proposed that reduced translation underpins the loser status of ribosome mutant, or Minute, cells. Here, using Drosophila, we show that reduced translation does not cause cell competition. Instead, we identify proteotoxic stress as the underlying cause of the loser status for Minute competition and competition induced by mahjong, an unrelated loser gene. RpS3+/− cells exhibit reduced autophagic and proteasomal flux, accumulate protein aggregates and can be rescued from competition by improving their proteostasis. Conversely, inducing proteotoxic stress is sufficient to turn otherwise wild-type cells into losers. Thus, we propose that tissues may preserve their health through a proteostasis-based mechanism of cell competition and cell selection
Field-induced delocalization and Zener breakdown in semiconductor superlattices
No full textWe investigate the energy spectrum and the electron dynamics of a band in a semiconductor superlattice as a function of the electric field. Linear optical spectroscopy shows that, for high fields, the well-known localization of the Bloch states is followed by a field-induced delocalization, associated with Zener breakdown. Using time-resolved measurements, we observe Bloch oscillations in a regime where they are damped by Zener breakdown
Why do winners keep winning? Androgen mediation of winner but not loser effects in cichlid fish
No full textAnimal conflicts are influenced by social experience such that a previous winning experience increases the probability of winning the next agonistic interaction, whereas a previous losing experience has the opposite effect. Since androgens respond to social interactions, increasing in winners and decreasing in losers, we hypothesized that socially induced transient changes in androgen levels could be a causal mediator of
winner/loser effects. To test this hypothesis, we staged fights between dyads of size-matched males of the Mozambique tilapia (Oreochromis mossambicus). After the first contest, winners were treated with the antiandrogen cyproterone acetate and losers were supplemented with 11-ketotestosterone. Two hours after the end of the first fight, two contests were staged simultaneously between the winner of the first fight and a
naive male and between the loser of first fight and another naive male. The majority (88%) of control winners also won the second interaction, whereas the majority of control losers (87%) lost their second fight, thus confirming the presence of winner/loser effects in this species. As predicted, the success of anti-androgen-treated winners in the second fight decreased significantly to chance levels (44%), but the success of androgenized losers (19%) did not show a significant increase. In summary, the treatment with anti-androgen blocks the winner effect, whereas androgen administration fails to reverse the loser effect, suggesting an involvement of androgens on the winner but not on the loser effect
An investigation of anomalies at Istanbul Securities Exchange : winner-loser effect
No full textCataloged from PDF version of article.Includes bibliographical references (leaves 27-28).In this study , the presence of winner -1 oser effect
in Istanbul Stock Exchange is investigated. Tests are
done for the period of January .1988 - December 1992.
Past performance is used to form the " Winner " and
"Loser" portfolios pri or to the lest period. Duration for past performance measure ments change from 1 month to 48 months.Test periods change from 3 months to 36 months.
The results show that, in the first month of the
test period, loser portfolio outperforms the winner
p o r t f o l i o . This ef f ect is e m p h a s i z e d if the first mont h
of the lest period is January.
The above results carry similarities with the
empirical results obtained from slock markets of USA
and Japan.Sayın, Gürka
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