A rapid rate of sex-chromosome turnover and non-random transitions in true frogs.

The canonical model of sex-chromosome evolution predicts that, as recombination is suppressed along sex chromosomes, gametologs will progressively differentiate, eventually becoming heteromorphic. However, there are numerous examples of homomorphic sex chromosomes across the tree of life. This homomorphy has been suggested to result from frequent sex-chromosome turnovers, yet we know little about which forces drive them. Here, we describe an extremely fast rate of turnover among 28 species of Ranidae. Transitions are not random, but converge on several chromosomes, potentially due to genes they harbour. Transitions also preserve the ancestral pattern of male heterogamety, in line with the 'hot-potato' model of sex-chromosome transitions, suggesting a key role for mutation-load accumulation in non-recombining genomic regions. The importance of mutation-load selection in frogs might result from the extreme heterochiasmy they exhibit, making frog sex chromosomes differentiate immediately from emergence and across their entire length

A MODEST review

We present an account of the state of the art in the fields explored by the research community invested in 'Modeling and Observing DEnse STellar systems'. For this purpose, we take as a basis the activities of the MODEST-17 conference, which was held at Charles University, Prague, in September 2017. Reviewed topics include recent advances in fundamental stellar dynamics, numerical methods for the solution of the gravitational N-body problem, formation and evolution of young and old star clusters and galactic nuclei, their elusive stellar populations, planetary systems, and exotic compact objects, with timely attention to black holes of different classes of mass and their role as sources of gravitational waves. Such a breadth of topics reflects the growing role played by collisional stellar dynamics in numerous areas of modern astrophysics. Indeed, in the next decade, many revolutionary instruments will enable the derivation of positions and velocities of individual stars in the Milky Way and its satellites and will detect signals from a range of astrophysical sources in different portions of the electromagnetic and gravitational spectrum, with an unprecedented sensitivity. On the one hand, this wealth of data will allow us to address a number of long-standing open questions in star cluster studies; on the other hand, many unexpected properties of these systems will come to light, stimulating further progress of our understanding of their formation and evolution.Comment: 42 pages; accepted for publication in 'Computational Astrophysics and Cosmology'. We are much grateful to the organisers of the MODEST-17 conference (Charles University, Prague, September 2017). We acknowledge the input provided by all MODEST-17 participants, and, more generally, by the members of the MODEST communit

Epizoic bryozoans, horseshoe crabs, and other mobile benthic substrates

Bulletin of Marine Science582368-384BMRS

Cervical visual inspection with acetic acid (VIA) and oncogenic human papillomavirus screening in rural indigenous guatemalan women: Time to rethink VIA

Single-visit “screen-and-treat” strategies using visual inspection with acetic acid (VIA) and cryotherapy (liquid nitrous oxide ablation) in low-resource settings are commonly used to de-tect and treat precancerous lesions for cervical cancer prevention. This study compared VIA sensi-tivity and specificity in rural indigenous Guatemalan communities, to that of oncogenic human papillomavirus (HPV) testing for detection of precancerous changes, using cytology as the reference standard. Between 3–8 September 2017, trained nurses examined 222 women aged 23–58 years with VIA. Specimens for liquid-based cytology and HPV testing were obtained prior to VIA with a cyto-brush and transported in PreservCyt to a US clinical laboratory. VIA and HPV test sensitivities were assessed as proportions of women with abnormal cytology that had abnormal VIA or HPV results, respectively, and specificities, as proportions with normal cytology with normal VIA or negative HPV tests. Of 222 women, 18 (8.1%) had abnormal cytology (1 carcinoma in a participant who received VIA-based cryotherapy in 2015, 4 high-and 5 low-grade squamous intraepithelial lesions, and 8 atypical squamous cells of undetermined significance (ASCUS)). Excluding ASCUS, sensitivities of VIA and HPV were 20.0% and 100%, respectively. VIA-based screening may not be accepta-ble for detecting precancerous lesions, and field cryotherapy for preventing malignancy. The World Health Organization recommended in 2021 “…using HPV DNA detection as the primary screening test rather than VIA or cytology.”. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]