1,721,179 research outputs found
Erosion of behavioural plasticity and pace-of-life shifts under multigenerational pharmaceutical pollution
No full textResearch Highlight: Aich, U., Polverino, G., Yazdan Parast, F., Melo, G. C., Tan, H., Howells, J., Nosrati, R., & Wong, B. B. M. (2024). Long-term effects of widespread pharmaceutical pollution on trade-offs between behavioural, life history and reproductive traits in fish. Journal of Animal Ecology. . Pharmaceutical pollutants are increasingly common in aquatic ecosystems, and organisms living there are the unintended targets of these compounds, originally designed for humans. However, our understanding of these effects remains limited. In a recent study, Aich et al. (2024) investigated the effects of fluoxetine on a small freshwater fish, the guppy (Poecilia reticulata), with particular emphasis on behaviour. The authors found that, after multigenerational exposure to ecologically relevant concentrations of this compound, there was minimal impact on average behavioural traits at the population level. However, fluoxetine exposure reduced within-individual behavioural plasticity and altered the delicate equilibrium among these traits. These findings could have far-reaching evolutionary implications for how individuals and populations may respond to environmental changes and highlight the need for behavioural ecotoxicology to move beyond population-level effects. This research provides valuable insights into the subtle and multifaceted-yet profound-impacts of pollutants on ecological and evolutionary processes, highlighting the importance of studying behavioural responses at the individual level to predict how populations will respond to our rapidly changing world
Male sperm storage impairs sperm quality in the zebrafish
Full text linkVariation in sperm traits is widely documented both at inter- and intraspecific level. However, sperm traits vary also between ejaculates of the same male, due for example, to fluctuations in female availability. Variability in the opportunities to mate can indeed have important consequences for sperm traits, as it determines how often sperm are used, and thus the rate at which they are produced and how long they are stored before the mating. While being stored within males’ bodies, sperm are subjected to ageing due to oxidative stress. Sperm storage may significantly impair sperm quality, but evidence linking male sperm storage and variation in sperm traits is still scarce. Here, we tested the effect of the duration of sperm storage on within-male variation in sperm traits in the zebrafish, Danio rerio. We found that without mating opportunities, sperm number increased as storage duration increased, indicating that sperm continue to be produced and accumulate over time within males without being discharged in another way. Long sperm storage (12 days) was associated with an overall impairment in sperm quality, namely sperm motility, sperm longevity, and sperm DNA fragmentation, indicating that sperm aged, and their quality declined during storage. Our results confirm that male sperm storage may generate substantial variation in sperm phenotype, a source of variation which is usually neglected but that should be accounted for in experimental protocols aiming to assay sperm traits or maximise fertilization success
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The MDM2 inhibitor Nutlin-3 modulates dendritic cell-induced T cell proliferation
No full textNutlin-3, a small molecule inhibitor of the MDM2/p53 interaction, has been recently taken into consideration as a promising therapeutic tool for tumor treatment based on its ability to stabilize and activate the p53 transcription factor pathway. Since Nutlin-3 displays non cell-autonomous tumor-suppressor activities, we wanted to investigate its effect on dendritic cell functions, given the central role of these cells in the modulation of the immune response. We found that Nutlin-3 alone slightly affected the levels of major histocompatibility complex and costimulatory molecules and significantly promoted the ability of dendritic cells to stimulate T cells in the mixed lymphocyte reaction. Taken together, our findings suggest that the ability of Nutlin-3 to modulate dendritic cell functions and therefore lymphocyte proliferation might represent an additional important mechanism by which Nutlin-3 exerts its non cell-autonomous tumor-suppression function. © 2012 American Society for Histocompatibility and Immunogenetics
The bold and the sperm: Positive association between boldness and sperm number in the guppy
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