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Summary Genome‐wide association studies (GWAS) in plants typically suffer from limited statistical power. An alternative to the logistical and cost challenge of increasing sample sizes is to gain power by meta‐analysis using information from independent studies. We carried out GWAS for growth traits with six single‐marker models and regional heritability mapping (RHM) in four Eucalyptus breeding populations independently and by Joint‐GWAS, using gene and segment‐based models, with data for 3373 individuals genotyped with a communal EUChip60KSNP platform. While single‐single nucleotide polymorphism (SNP) GWAS hardly detected significant associations at high‐stringency in each population, gene‐based Joint‐GWAS revealed nine genes significantly associated with tree height. Associations detected using single‐SNP GWAS, RHM and Joint‐GWAS set‐based models explained on average 3–20% of the phenotypic variance. Whole‐genome regression, conversely, captured 64–89% of the pedigree‐based heritability in all populations. Several associations independently detected for the same SNPs in different populations provided unprecedented GWAS validation results in forest trees. Rare and common associations were discovered in eight genes involved in cell wall biosynthesis and lignification. With the increasing adoption of genomic prediction of complex phenotypes using shared SNPs and much larger tree breeding populations, Joint‐GWAS approaches should provide increasing power to pinpoint discrete associations potentially useful toward tree breeding and molecular applications.

As HIV research and prevention efforts increasingly target gay men in relationships, situational factors such as couple serostatus and agreements about sex become central to examinations of risk. Discordant gay couples are of particular interest because the risk of HIV infection is seemingly near-at-hand. Yet little is known about their sexual behaviors, agreements about sex, and safer sex efforts. The present study utilized longitudinal semi-structured, qualitative interviews to explore these issues among 12 discordant couples. Findings show that nearly every couple had agreements about reducing the likelihood of HIV transmission from one partner to the other. Negotiating these agreements involved establishing a level of acceptable risk, determining condom use, and employing other risk-reduction techniques, such as seropositioning and withdrawal. For half of the couples, these agreements did not involve using condoms; only two couples reported consistent condom use. Despite forgoing condoms, however, none reported seroconversion over the course of data collection. Additional issues are raised where long-term HIV prevention is concerned. Future prevention efforts with discordant couples should work with, rather than fight against, the couple’s decision to use condoms and endeavor to complement and accentuate their other safer sex efforts.

A thorough understanding of the heritability, genetic correlations and additive and non-additive variance components of tree growth and wood properties is a requisite for effective tree breeding. This knowledge is essential to maximize genetic gain, that is, the amount of increase in trait performance achieved annually through directional selection. Understanding the genetic attributes of traits targeted by breeding is also important to sustain decade-long genetic progress, that is, the progress made by increasing the average genetic value of the offspring as compared to that of the parental generation. In this study, we report quantitative genetic parameters for fifteen growth, wood chemical and physical traits for the world-famous Eucalyptus urograndis hybrid ( E . grandis × E . urophylla ). These traits directly impact the optimal use of wood for cellulose pulp, paper, and energy production. A population of 1,000 trees sampled in a progeny trial was phenotyped directly or following the development and use of near-infrared spectroscopy calibration models. Trees were genotyped with 33,398 SNPs and 24,001 DArT-seq genome-wide markers and genomic realized relationship matrices (GRM) were used for parameter estimation with an individual-tree additive-dominant mixed model. Wood chemical properties and wood density showed stronger genetic control than growth, cellulose and fiber traits. Additive effects are the main drivers of genetic variation for all traits, but dominance plays an equally or more important role for growth, singularly in this hybrid. GRM´s with >10,000 markers provided stable relationships estimates and more accurate parameters than pedigrees by capturing the full genetic relationships among individuals and disentangling the non-additive from the additive genetic component. Low correlations between growth and wood properties indicate that simultaneous selection for wood traits can be applied with minor effects on genetic gain for growth. Conversely, moderate to strong correlations between wood density and chemical traits exist, likely due to their interdependency on cell wall structure such that responses to selection will be connected for these traits. Our results illustrate the advantage of using genome-wide marker data to inform tree breeding in general and have important consequences for operational breeding of eucalypt urograndis hybrids.

The dissemination of the practice of collaborative authorship (co-authorship) in Brazil and in the international scientific community has been accompanied by an increasing occurrence of frauds, manipulations and other deviations in the assignment of responsibility for a scientific paper. This article discusses the criteria for authorship attribution, the reasons for the growing indices of co-authorship and the challenges to determine authorship in electronic journals. Through literature review and case study (bibliographic search in the scientific database), it has been shown ways to avoid that "misbehaviour" deviance regarding the authorship attribution affect the credibility of science.Descriptors: Authorship. Periodicals. Scientific communication. Scientific production. ResumoA disseminação da prática de coautoria no Brasil e na comunidade internacional tem sido acompanhada pelo aumento no registro de fraudes, manipulações e outros desvios ao definir a responsabilidade por um trabalho científico. Este artigo discorre sobre os critérios utilizados para atribuição da autoria, as razões para o crescimento dos índices de coautoria e os desafios para estabelecer a autoria em periódicos eletrônicos. Por meio de revisão bibliográfica e estudo de caso (a partir de levantamento de base de dados), aponta caminhos para evitar que "desvios de comportamento" quanto à atribuição de autoria abalem a credibilidade da ciência.Descritores: Autoria. Publicações periódicas. Comunicação científica. Produção científica.