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Our aim was to adapt and validate a Brazilian Portuguese version of the Twin Relationship Questionnaire developed by Fortuna et al. (2010) and validated by H. Segal and KnafoNoam (2019) in Israel. The respondents were 862 Brazilian mothers of twins (N = 1724 twins) with mean age of 35 years (SD = 6.1). The majority of the sample lived in the Southeast (61.8%) or in the South (24.5%) of Brazil. We conducted a Multilevel Confirmatory Factor Analysis with the pair of twins as second level variable, and the fivefactor structure (closeness, dependence, conflict, dominance, and rivalry) proposed by the original validation study of H. Segal and Knafo-Noam (2019) was confirmed. The final model retained 15 items out of 22 proposed in the original version of the questionnaire. Although the TRQ-BR has fewer items, the accuracy compared to the original questionnaire was maintained. Mixed Model Analysis (LMM) of TRQ scores were used to investigate twins’ relationships as a function of zygosity, age groups, and sex in order to provide evidence of convergent validity of the instrument. As expected, mothers perceived monozygotic twins (MZ) as more depedent than dizygotic twins (DZ). Furthermore, male twin pairs were considered more conflictive when compared to female twins. The present study showed that TRQ-BR is an adequate instrument for research purposes in the Brazilian population. It can also be useful for applied areas such as clinical and educational fields. [ABSTRACT FROM AUTHOR]

The present study investigates the twinning rates in the city of São Paulo, Brazil, during the years 2003–2014. The data were drawn from the Brazilian Health Department database of Sistema de Informações de Nascidos Vivos de São Paulo—SINASC (Live Births Information System of São Paulo). In general, more information is available on the incidence of twinning in developed countries than in developing ones. A total of 24,589 twin deliveries and 736 multiple deliveries were registered in 140 hospitals of São Paulo out of a total of 2,056,016 deliveries during the studied time period. The overall average rates of singleton, twin, and multiple births per 1,000 maternities (‰) were 987.43, 11.96 (dizygotic (DZ) rate was 7.15 and monozygotic (MZ) 4.42), and 0.36, respectively. We further regressed maternal age and historical time period on percentage of singleton, twin, and multiple birth rates. Our results indicated that maternal age strongly positively predicted twin and multiple birth rates, and negatively predicted singleton birth rates. The historical time period also positively, although weakly, predicted twin birth rates, and had no effect on singleton or multiple birth rates. Further, after applying Weinberg's differential method, we computed regressions separately for the estimated frequencies of DZ and MZ twin rates. DZ twinning was strongly positively predicted by maternal age and, to a smaller degree, by time period, while MZ twinning increased marginally only with higher maternal age. Factors such as increasing body mass index or air pollution can lead to the slight historical increase in DZ twinning rates. Importantly, consistent with previous cross-cultural and historical research, our results support the existence of an age-dependent physiological mechanism that leads to a strong increase in twinning and multiple births, but not singleton births, among mothers of higher age categories. From the ultimate perspective, twinning and multiple births in later age can lead to higher individual reproductive success near the end of the reproductive career of the mother. [ABSTRACT FROM PUBLISHER]

Spodoptera frugiperda (J.E. Smith) is the main pest of maize in Brazil and its control has been targeted by Bt maize hybrids. Generally, Bt maize hybrids possess the transgenic locus in a hemizygous condition, that is, containing only one copy of the Bt allele. However, studies have shown that maize hybrids with an additional transgenic allele, namely, in a homozygous state, increases transgenic protein expression. Our aim in this study was to evaluate whether the transgenic event TC1507 x MON89034 x NK603 in homozygosis increases Bt protein expression levels and, consequently, reduces S. frugiperda leaf-feeding injury and larval survival which affects maize grain yield. Leaf-feeding injury of S. frugiperda was 29% lower on homozygous hybrids relative to their isogenic hemizygous versions. Isogenic homozygous and hemizygous hybrids did not differ in grain yield in this study. S. frugiperda survivorship on homozygous hybrids was significantly lower than on their hemizygous isogenic versions (16.9% and 38.5%, respectively). Homozygous hybrids presented higher Cry1F, Cry1A.105, and Cry2Ab2 protein expression levels relative to their isogenic hemizygous versions (approximately 1.5-, 2.0-, and 2.5-fold, respectively). The Bt maize event TC1507 x MON89034 x NK603 in a homozygous state increases Bt protein expression levels and the control of S. frugiperda. Therefore, the deployment of homozygous transgenic maize hybrids to farmers is more desirable than the hemizygous versions. • Homozygous Bt hybrids increased the control of S. frugiperda. • Homozygous Bt hybrids presented less leaf injury caused by S. frugiperda. • The additional Bt allele on maize hybrids increased the expression of Bt proteins. • Grain yield did not differ between homozygous and hemizygous Bt hybrids. [ABSTRACT FROM AUTHOR]