ISW1a modulates cohesin distribution in centromeric and pericentromeric regions.

Cohesin is a highly conserved, multiprotein complex whose canonical function is to hold sister chromatids together to ensure accurate chromosome segregation. Cohesin association with chromatin relies on the Scc2-Scc4 cohesin loading complex that enables cohesin ring opening and topological entrapment of sister DNAs. To better understand how sister chromatid cohesion is regulated, we performed a proteomic screen in budding yeast that identified the Isw1 chromatin remodeler as a cohesin binding partner. In addition, we found that Isw1 also interacts with Scc2-Scc4. Lack of Isw1 protein, the Ioc3 subunit of ISW1a or Isw1 chromatin remodeling activity resulted in increased accumulation of cohesin at centromeres and pericentromeres, suggesting that ISW1a may promote efficient translocation of cohesin from the centromeric site of loading to neighboring regions. Consistent with the role of ISW1a in the chromatin organization of centromeric regions, Isw1 was found to be recruited to centromeres. In its absence we observed changes in the nucleosomal landscape at centromeres and pericentromeres. Finally, we discovered that upon loss of RSC functionality, ISW1a activity leads to reduced cohesin binding and cohesion defect. Taken together, our results support the notion of a key role of chromatin remodelers in the regulation of cohesin distribution on chromosomes.

Phylogenomic analysis reveals five independently evolved African forage grass clades in the genus Urochloa.

BACKGROUND AND AIMS: The grass genus Urochloa (Brachiaria) sensu lato includes forage crops that are important for beef and dairy industries in tropical and sub-tropical Africa, South America and Oceania/Australia. Economically important species include U. brizantha, U. decumbens, U. humidicola, U. mutica, U. arrecta, U. trichopus, U. mosambicensis and Megathyrsus maximus, all native to the African continent. Perennial growth habits, large, fast growing palatable leaves, intra- and interspecific morphological variability, apomictic reproductive systems and frequent polyploidy are widely shared within the genus. The combination of these traits probably favoured the selection for forage domestication and weediness, but trait emergence across Urochloa cannot be modelled, as a robust phylogenetic assessment of the genus has not been conducted. We aim to produce a phylogeny for Urochloa that includes all important forage species, and identify their closest wild relatives (crop wild relatives). Finally, we will use our phylogeny and available trait data to infer the ancestral states of important forage traits across Urochloa s.l. and model the evolution of forage syndromes across the genus. METHODS: Using a target enrichment sequencing approach (Angiosperm 353), we inferred a species-level phylogeny for Urochloa s.l., encompassing 54 species (~40 % of the genus) and outgroups. Phylogenies were inferred using a multispecies coalescent model and maximum likelihood method. We determined the phylogenetic placement of agriculturally important species and identified their closest wild relatives, or crop wild relatives, based on well-supported monophyly. Further, we mapped key traits associated with Urochloa forage crops to the species tree and estimated ancestral states for forage traits along branch lengths for continuous traits and at ancestral nodes in discrete traits. KEY RESULTS: Agricultural species belong to five independent clades, including U. brizantha and U. decumbens lying in a previously defined species complex. Crop wild relatives were identified for these clades supporting previous sub-generic groupings in Urochloa based on morphology. Using ancestral trait estimation models, we find that five morphological traits that correlate with forage potential (perennial growth habits, culm height, leaf size, a winged rachis and large seeds) independently evolved in forage clades. CONCLUSIONS: Urochloa s.l. is a highly diverse genus that contains numerous species with agricultural potential, including crop wild relatives that are currently underexploited. All forage species and their crop wild relatives naturally occur on the African continent and their conservation across their native distributions is essential. Genomic and phenotypic diversity in forage clade species and their wild relatives need to be better assessed both to develop conservation strategies and to exploit the diversity in the genus for improved sustainability in Urochloa cultivar production.

Complex polyploid and hybrid species in an apomictic and sexual tropical forage grass group: genomic composition and evolution in Urochloa (Brachiaria) species.

BACKGROUND AND AIMS: Diploid and polyploid Urochloa (including Brachiaria, Panicum and Megathyrsus species) C4 tropical forage grasses originating from Africa are important for food security and the environment, often being planted in marginal lands worldwide. We aimed to characterize the nature of their genomes, the repetitive DNA and the genome composition of polyploids, leading to a model of the evolutionary pathways within the group including many apomictic species. METHODS: Some 362 forage grass accessions from international germplasm collections were studied, and ploidy was determined using an optimized flow cytometry method. Whole-genome survey sequencing and molecular cytogenetic analysis were used to identify chromosomes and genomes in Urochloa accessions belonging to the 'brizantha' and 'humidicola' agamic complexes and U. maxima. KEY RESULTS: Genome structures are complex and variable, with multiple ploidies and genome compositions within the species, and no clear geographical patterns. Sequence analysis of nine diploid and polyploid accessions enabled identification of abundant genome-specific repetitive DNA motifs. In situ hybridization with a combination of repetitive DNA and genomic DNA probes identified evolutionary divergence and allowed us to discriminate the different genomes present in polyploids. CONCLUSIONS: We suggest a new coherent nomenclature for the genomes present. We develop a model of evolution at the whole-genome level in diploid and polyploid accessions showing processes of grass evolution. We support the retention of narrow species concepts for Urochloa brizantha, U. decumbens and U. ruziziensis, and do not consider diploids and polyploids of single species as cytotypes. The results and model will be valuable in making rational choices of parents for new hybrids, assist in use of the germplasm for breeding and selection of Urochloa with improved sustainability and agronomic potential, and assist in measuring and conserving biodiversity in grasslands.

Evaluating a Theory-Based Online Program for Preventing Sexual Aggression: An Experimental-Longitudinal Study With German University Students.

This pre-registered study evaluated an intervention designed to reduce sexual aggression perpetration and victimization by changing risky scripts for consensual sexual interactions and corresponding risky sexual behavior, and by improving sexual self-esteem, refusal assertiveness, and initiation assertiveness. In a four-wave longitudinal study covering 23 months, 1181 university students in Germany (762 female) were randomly assigned to an intervention and a no-intervention control group. The intervention group completed six weekly modules addressing the targeted theory-based risk and vulnerability factors of sexual aggression perpetration and victimization. Controlling for baseline levels (T1), the intervention group showed less risky sexual scripts one week post-intervention (T2), which predicted less risky sexual behavior nine months later (T3), which predicted lower odds of sexual aggression perpetration and victimization 12 months later (T4). No direct intervention effects on rates of sexual aggression perpetration and victimization at T3 and T4 were found. No indirect intervention effect on sexual aggression was found via sexual self-esteem and sexual assertiveness. However, sexual self-esteem at T2, which was higher in the intervention group, predicted lower odds of sexual aggression victimization at T3 via higher initiation assertiveness at T3. Implications for reducing sexual aggression and conceptualizing risk and vulnerability factors of sexual aggression are discussed.

Unacknowledged and missed cases of sexual victimization: A comparison of responses to broad versus behaviorally specific questions.

From the beginning of systematic research on sexual victimization, it has been recognized that a substantial proportion of women report nonconsensual sexual experiences meeting the defining criteria of rape in response to behaviorally specific items, but do not acknowledge their experience as rape in response to broad questions about whether they have ever been raped. Recent studies suggest that rates of unacknowledged rape may be as high or even higher among men than among women. This study examined rates of unacknowledged female and male victims of rape and sexual assault by comparing responses to behaviorally specific items of the Sexual Aggression and Victimization Scale (SAV-S) with responses to broad questions using the labels of sexual assault and rape (SARA) in 593 participants (303 women) in Germany. As predicted, more women and men were classified as rape victims based on behaviorally specific items than on the basis of the broad rape item. The rates of unacknowledged rape were about 60% for women and 75% for men. The gender difference was not significant. Against our prediction, no significant differences in acknowledgement of sexual assault were found in relation to coercive strategy and victim-perpetrator relationship. Few cases of rape and sexual assault identified by the SARA items were missed by the behaviorally specific questions. The implications for establishing prevalence rates of rape and sexual assault and for comparing victims and nonvictims in terms of vulnerability factors and outcomes of sexual victimization are discussed.

Prevalence of Sexual Aggression Victimization and Perpetration in a German University Student Sample.

This study examined the prevalence of sexual aggression perpetration and victimization in a sample of 1,172 students (755 female, 417 male) from four universities in Germany. All participants were asked about both victimization by, and perpetration of, sexual aggression since the age of 14 years, using the Sexual Aggression and Victimization Scale (SAV-S). Prevalence rates were established for different coercive strategies, sexual acts, and victim-perpetrator relationships. Both same-sex and opposite-sex victim-perpetrator constellations were examined. The overall victimization rate was 62.1% for women and 37.5% for men. The overall perpetration rate was 17.7% for men and 9.4% for women. Prevalence rates of both victimization and perpetration were higher for participants who had sexual contacts with both opposite-sex and same-sex partners than for participants with exclusively opposite-sex partners. Significant overlap was found between victim and perpetrator status for men and women as well as for participants with only opposite-sex and both opposite-sex and same-sex partners. A disparity between (higher) victimization and (lower) perpetration reports was found for both men and women, suggesting a general underreporting of perpetration rather than a gendered explanation in terms of social desirability or the perception of consent cues. The findings are placed in the international research literature on the prevalence of sexual aggression before and after the #metoo campaign, and their implications for prevention efforts are discussed.

Cytogenetic events in the endosperm of amphiploid Avena magna × A. longiglumis.

This study analysed cytogenetic events occurring in the syncytial endosperm of the Avena magna H. C. Murphy & Terrell × Avena longiglumis Durieu amphiploid, which is a product of two wild species having different genomes. Selection through the elimination of chromosomes and their fragments, including those translocated, decreased the level of ploidy in the endosperm below the expected 3n, leading to the modal number close to 2n. During intergenomic translocations, fragments of the heterochromatin-rich C-genome were transferred to the D and Al genomes. Terminal and non-reciprocal exchanges dominated, whereas other types of translocations, including microexchanges, were less common. Using two probes and by counterstaining with DAPI, the A. longiglumis and the rare exchanges between the D and Al genomes were detected by GISH. The large discontinuity in the probe labelling in the C chromosomes demonstrated inequality in the distribution of repetitive sequences along the chromosome and probable intragenomic rearrangements. In the nucleus, the spatial arrangement of genomes was non-random and showed a sectorial-concentric pattern, which can vary during the cell cycle, especially in the less stable tissue like the hybrid endosperm.

Checklist for responsible deep learning modeling of medical images based on COVID-19 detection studies.

The sudden outbreak and uncontrolled spread of COVID-19 disease is one of the most important global problems today. In a short period of time, it has led to the development of many deep neural network models for COVID-19 detection with modules for explainability. In this work, we carry out a systematic analysis of various aspects of proposed models. Our analysis revealed numerous mistakes made at different stages of data acquisition, model development, and explanation construction. In this work, we overview the approaches proposed in the surveyed Machine Learning articles and indicate typical errors emerging from the lack of deep understanding of the radiography domain. We present the perspective of both: experts in the field - radiologists and deep learning engineers dealing with model explanations. The final result is a proposed checklist with the minimum conditions to be met by a reliable COVID-19 diagnostic model.

Prevalence of teen dating violence in Europe: A systematic review of studies since 2010.

Violence in adolescent relationships is a common problem with numerous negative short- and long-term consequences. Because most of the evidence on teen dating violence (TDV) synthesized in reviews comes from North American studies, this review aimed to compile evidence on prevalence rates of TDV based on studies identified for Europe only. Specifically, we considered different forms of TDV victimization and perpetration, gender differences, and its measurement. A systematic literature search of the most popular databases Ebsco and PubMed yielded a total of N = 34 studies, with most of the studies identified for Spain, and only a few studies in other European countries. In sum, the results revealed a great variability in prevalence rates across and within the European countries, a common pattern of gender differences, and a wide range of applied measures, corresponding with the evidence from the North American studies. Implications for future research and policy were discussed.

Physical teen dating violence in high school students in Slovenia: Prevalence and correlates.

Although teen dating violence (TDV) is internationally recognized as a serious threat to adolescents' health and well-being, almost no data is available for Slovenian youth. Hence, the purpose of this study was to examine the prevalence and predictors of TDV among Slovenian adolescents for the first time. Using data from the SPMAD study (Study of Parental Monitoring and Adolescent Delinquency), 330 high school students were asked about physical TDV victimization and perpetration as well as about their dating history, relationship conflicts, peers' antisocial behavior, and informal social control by family and school. A substantial number of female and male adolescents reported victimization (16.7% of female and 12.7% of male respondents) and perpetration (21.1% of female and 6.0% of male respondents). Furthermore, the results revealed that lower age at the first relationship, relationship conflicts, and school informal social control were associated with victimization, whereas being female, relationship conflicts, having antisocial peers, and family informal social control were linked to perpetration. Implications of the study findings were discussed.

The role of moral neutralization of aggression and justification of violence against women in predicting physical teen dating violence perpetration and monitoring among adolescents in Switzerland.

Although dating violence poses a serious threat to adolescents' health and well-being around the globe, little evidence is available for Europe in general and Switzerland in particular. Also, evidence on the role of cognitive predictors related to a more general justification of aggressive behavior and gender-based violence is lacking. Therefore, this two-wave longitudinal study conducted with Swiss adolescents (N = 646) examined moral neutralization of aggression and justification of violence against women as predictors of physical dating violence perpetration and monitoring. As expected, higher moral neutralization of aggression predicted a higher likelihood of perpetrating physical dating violence and monitoring among both female and male adolescents. Justification of violence against women was positively associated with physical dating violence perpetration among males, but negatively among females. Also, a negative relationship was found with monitoring among females. The role of gender and implications of these findings for research, practice, and policy are discussed.

Correction to: Instability of endosperm development in amphiploids and their parental species in the genus Avena L.

The article 'Instability of endosperm development in amphiploids and their parental species in the genus Avena L.', written by Paulina Tomaszewska and Romuald Kosina, was originally published electronically on the publisher's internet portal on 22 May with an incorrect copyright line. As the article was due to be published with Open Choice, the copyright of the article changed on 29 August 2018 to © The Author(s) 2018 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0 ), which permits use, duplication, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license and indicate if changes were made.

Predictors of Sexual Aggression Victimization and Perpetration Among Polish University Students: A Longitudinal Study.

This two-wave study investigated predictors of sexual aggression victimization and perpetration in a convenience sample of 318 Polish university students (214 women), considering males and females from the perspective of both victims and perpetrators. At T1, we assessed participants' risky sexual scripts (defined as cognitive representations of consensual sexual interactions containing elements related to sexual aggression), risky sexual behavior, pornography use, religiosity, sexual self-esteem, and attitudes toward sexual coercion. These variables were used to predict sexual aggression perpetration and victimization reports obtained 12 months later (T2) for two time windows: (a) since the age of 15 until a year ago and (b) in the past year. As expected, risky sexual scripts were linked to risky sexual behavior and indirectly increased the likelihood of victimization in both time windows. Lower sexual self-esteem predicted sexual victimization since age 15, but not in the past 12 months. Pornography use and religiosity indirectly predicted victimization via risky scripts and behavior. Attitudes toward sexual coercion were a prospective predictor of sexual aggression perpetration. The results extend the international literature on sexual aggression and have implications for sexual education and sexual aggression prevention programs.

Instability of endosperm development in amphiploids and their parental species in the genus Avena L.

KEY MESSAGE: The development of oat endosperm is modified by chromatin and nuclei elimination, intrusive growth of cell walls, and polyploidisation of cell clones. The last event is correlated with somatic crossing-over. Grass endosperm is a variable tissue in terms of its cytogenetics and development. Free-nuclear syncytium and starchy and aleurone endosperm were the main focus of the research. These were studied in oat amphiploids (4x, 6x, and 8x) and parental species (2x, 4x, and 6x). What the levels of cytogenetic disorders and developmental anomalies in species versus hybrids are, and, what the factors are determining phenotypes of both tissue components, are open questions for oats. Chromosome bridges and micronuclei are the main cytogenetic disorders showing the elimination of parts of genomes. Bridges are formed by the AT-heterochromatin-rich and -free ends of chromosomes. In the starchy tissue, various sectors are separated structurally due to the elongation or intrusive growth of aleurone cells. The development of the aleurone layer is highly disturbed locally due to the amplification of aleurone cell divisions. Changes related to their structure and metabolism occur in the aleurone cells, for example, clones of small versus large aleurone cells. Somatic crossing-over (SCO) is expressed in clones of large polyploidised cells (r = 0.80***), giving rise to new aleurone phenotypes. The multivariate description of the endosperm instability showed that endospermal disorders were more frequent in amphiploids than in the oat species. Avena strigosa and the amphiploid A. fatua × A. sterilis appeared to be extreme units in an ordination space. Nuclear DNA elimination, periclinal and multidirectional cytokineses, polyploidisation, intrusive growth, and SCO appeared to be important factors determining oat endospermal variations.

Prevalence and correlates of young people's sexual aggression perpetration and victimisation in 10 European countries: a multi-level analysis.

Data are presented on young people's sexual victimisation and perpetration from 10 European countries (Austria, Belgium, Cyprus, Greece, Lithuania, the Netherlands, Poland, Portugal, Slovakia and Spain) using a shared measurement tool (N = 3480 participants, aged between 18 and 27 years). Between 19.7 and 52.2% of female and between 10.1 and 55.8% of male respondents reported having experienced at least one incident of sexual victimisation since the age of consent. In two countries, victimisation rates were significantly higher for men than for women. Between 5.5 and 48.7% of male and 2.6 and 14.8% of female participants reported having engaged in a least one act of sexual aggression perpetration, with higher rates for men than for women in all countries. Victimisation rates correlated negatively with sexual assertiveness and positively with alcohol use in sexual encounters. Perpetration rates correlated positively with attitudes condoning physical dating violence and with alcohol use in men, and negatively with sexual assertiveness in women. At the country level, lower gender equality in economic power and in the work domain was related to higher male perpetration rates. Lower gender equality in political power and higher sexual assertiveness in women relative to men were linked to higher male victimisation rates.

Oat species and interspecific amphiploids show predominance of diploid nuclei in the syncytial endosperm.

Apart from apomictic types, the Polygonum-type eight-nuclear embryo sac is considered to be dominant in grasses. A triploid endosperm is formed as a result of double fertilisation. This study showed, for the first time, the dominance of diploid nuclei in the syncytial stage of the central cell of embryo sac in oat species and amphiploids. The dominance of diploid nuclei, which were the basis for the formation of polyploid nuclei, was weaker in amphiploids due to aneuploid events. The genomic in situ hybridisation method applied in the study did not distinguish the maternal and paternal haploid nuclei of embryo sac. However, this method demonstrated the lack of a set of genomes of one haploid nucleus. Embryological analyses of the initial stages of oat endosperm development revealed a fertilised egg cell, and two polar nuclei differing in size. It can be assumed that the formation of diploid oat endosperm occurred after the fusion of one polar nucleus and the nucleus of a male gamete, while the second polar nucleus gave rise to 1n nuclei. The levels of ploidy of syncytial nuclei were not influenced by both aneuploid events and correlated with pollen developmental anomalies. The differences in the analysed cytogenetic events distinguished amphiploids and their parental species in the ordination space.

A Theory-Based Intervention to Reduce Risk and Vulnerability Factors of Sexual Aggression Perpetration and Victimization in German University Students.

The current study evaluated an intervention program, designed by the authors and based on the theory of sexual scripts and social learning theory, to reduce empirically established risk and vulnerability factors of sexual aggression. A sample of 1,181 university students in Germany (762 female) were randomly assigned to an intervention and a no-intervention control group. The intervention group completed six modules addressing established antecedents of sexual aggression perpetration and victimization: risky sexual scripts, risky sexual behavior, low sexual self-esteem, low sexual assertiveness, acceptance of sexual coercion, and perceived realism of pornography. After baseline (T1), intervention effects were measured one week after the last module (T2), nine months later (T3), and another 12 months later (T4). The intervention group showed significantly less risky sexual scripts and higher sexual self-esteem at T2, T3, and T4. The intervention indirectly reduced risky sexual behavior at T3 and T4 via less risky sexual scripts at T2 and increased sexual assertiveness at T3 and T4 via higher sexual self-esteem at T2. No intervention effects were found on the acceptance of sexual coercion and pornography realism. The implications of the findings for reducing the prevalence of sexual aggression perpetration and victimization are discussed.

Pathways from childhood sexual abuse to sexual aggression victimization and perpetration in adolescence and young adulthood: a three-wave longitudinal study.

BACKGROUND: Childhood sexual abuse (CSA) has been identified as a risk factor for later sexual aggression perpetration and vulnerability factor for sexual victimization. However, the use of cross-sectional designs, the focus on female victimization and male perpetration, and the lack of evidence from outside North America limit the existing knowledge base. OBJECTIVE: The study was designed to examine pathways from CSA to sexual revictimization and sexual aggression perpetration after the age of consent. METHOD: A total of 588 university students in Germany (308 female) took part in a three-wave longitudinal study covering 23 months. At each wave (T1-T3), all participants completed measures of sexual aggression victimization and perpetration. Experiences of CSA were measured at T1. RESULTS: The rate of CSA was significantly higher for women (20.8%) than for men (12.4%). Rates of sexual victimization for women were 60.9% at Time 1 (since age 14), 22.3% at Time 2 (since T1), and 17.4% at Time 3 (since T2). For men, the rates were 39.2% at Time 1, 15.9% at Time 2, and 14.1% at Time 3. Rates of sexual aggression perpetration for women were 10.6% at Time 1 (since age 14), 3.5% at Time 2 (since T1), and 3.6% at Time 3 (since T2). For men, the rates were 18.0% at Time 1, 6.2% at Time 2, and 3.8% at Time 3. The gender differences in victimization and perpetration were significant only at T1. CSA predicted higher odds of sexual aggression victimization and perpetration cross-sectionally at T1 and indirectly at T2 and T3 via T1. Gender did not moderate the associations. CONCLUSION: The results confirm previous findings of elevated rates of sexual aggression victimization and perpetration in adolescence and young adulthood in victims of CSA. The implications for understanding and preventing adverse sexuality-related outcomes of CSA are discussed.

Childhood sexual abuse has been linked to an increased vulnerability to sexual revictimization and risk of later sexual aggression perpetration.This longitudinal study based on a large sample of university students in Germany with three data waves covering 23 months shows that sexual abuse in childhood increases the odds of experiencing and engaging in sexual aggression in adolescence and young adulthood.The associations with later sexual aggression victimization and perpetration held for both female and male victims of childhood sexual abuse.