The U2 small nuclear ribonucleoprotein auxiliary factor (U2AF) is a heterodimeric splicing factor composed of 65-kDa (U2AF 65 ) and 35-kDa (U2AF 35) subunits. The large subunit of U2AF recognizes the intronic polypyrimidine tract, a sequence located adjacent to the 3 splice site that serves as an important signal for both constitutive and regulated pre-mRNA splicing. The small subunit U2AF35 interacts with the 3 splice site dinucleotide AG and is essential for regulated splicing. Like several other proteins involved in constitutive and regulated splicing, both U2AF 65 and U2AF 35 contain an arginine/ serine-rich (RS) domain. In the present study we determined the role of RS domains in the subcellular localization of U2AF. Both U2AF 65 and U2AF 35 are shown to shuttle continuously between the nucleus and the cytoplasm by a mechanism that involves carrier receptors and is independent from binding to mRNA. The RS domain on either U2AF 65 or U2AF 35 acts as a nuclear localization signal and is sufficient to target a heterologous protein to the nuclear speckles. Furthermore, the results suggest that the presence of an RS domain in either U2AF subunit is sufficient to trigger the nucleocytoplasmic import of the heterodimeric complex. Shuttling of U2AF between nucleus and cytoplasm possibly represents a means to control the availability of this factor to initiate spliceosome assembly and therefore contribute to regulate splicing.Pre-mRNA splicing is an essential step in eukaryotic gene expression that is often regulated in a cell type-specific or developmental manner. The splicing reaction takes place in the spliceosome, a multicomponent RNA-protein complex containing five uracil-rich small nuclear ribonucleoproteins (snRNP) 1 and 50 -100 non-snRNP protein splicing factors (1, 2). To ensure the precise excision of introns, components of the spliceosome recognize weakly conserved sequences in the pre-mRNA (3). The decision to splice a given pre-mRNA and the selection of splice sites takes place during the first stages of spliceosome assembly. These early steps are therefore crucial for splicing regulation (3-5). The stable association of U2 snRNP with the 3Ј region of the intron (3, 6, 7) requires an auxiliary factor, U2AF (8). U2AF consists of two subunits that form a stable heterodimer (9). U2AF 65 binds directly to the intronic polypyrimidine tract and is essential for splicing (10). U2AF35 recognizes the 3Ј splice site dinucleotide AG (11-13) and is required for the regulated splicing of a subset of pre-mRNAs (14).Regulatory mechanisms underlying the selection of alternative exons remain poorly defined (5, 15). A significant advance in understanding splice site recognition was provided by the observation that exon sequences also play a critical role in splicing. Constitutive as well as regulated exon splicing enhancers have been identified (16,17). These sequences contain binding sites for SR proteins (18, 19), a family of essential splicing factors with a modular structure consisting of one or two RRMs and a C-term...

The conventional soybean production has been re-establishing itself every year, due to the fact that the international market has demanded products with high agronomic performance and nutritional quality, free of genetically modified organisms. This study aimed to evaluate the adaptability of conventional soybean genotypes in the southwestern Goiás state (Rio Verde, Montividiu and Santa Helena de Goiás), Brazil, during the 2017/2018 and 2018/2019 crop seasons. A randomized blocks design was used, being tested eight genotypes (the cultivars BRS284, BRS283, BRS232, BRS317, NT11-1277, INT3459 and M6101 and the line NT1478SP). The grain and oil yields, as well as the oil and protein contents, were evaluated. Multi-environment analyses were performed using a heterogeneous residual variance model, and the GGE biplot analysis was used to describe the interrelationships between genotypes and environments. The most adapted and stable genotypes were BRS 317 for grain yield and BRS 283 for oil yield. They also corresponded more closely to the ideotype for the specific region, thus proving to be promising. NT1478SP showed the highest protein content. In the 2018/2019 crop season, Montividiu was more discriminating for the conventional soybean production, regarding grain and oil yields.

O cultivo de milho convencional vem retomando espaço no panorama agrícola nacional em função da dificuldade de controle do milho tiguera em culturas subsequentes. Entretanto, a deriva de glyphosate em lavouras adjacentes passou a ser uma preocupação entre os produtores e técnicos. Dessa forma o experimento foi instalado para avaliar o efeito de baixas doses de glyphosate na cultura e a capacidade de um bioestimulante a base de hormônios vegetais em reverter as injúrias causadas pelo herbicida, avaliando-se características morfológicas e taxa fotossintética de plantas de milho. Foi utilizado o delineamento inteiramente casualizados com quatro repetições em arranjo fatorial 5 X 2, sendo que o primeiro fator correspondeu a cinco doses de glyphosate (0; 10; 20; 30 e 40 g e.a. ha-1) e o segundo a ausência e presença do bioestimulante. As características avaliadas foram fitointoxicação, diâmetro do colmo, altura plantas e massa fresca de raiz e parte aérea, índice SPAD e taxa fotossintética. A maior dose de glyphosate provocou maior fitointoxicação, além de plantas com menor altura e menor índice SPAD. O bioestimulante proporcionou acréscimos no diâmetro de colmo, índice SPAD e taxa fotossintética. A presença de bioestimulante não proporcionou efeito reparador nos efeitos deletérios provocados pelo glyphosate em plantas de milho convencional.