The glyphosate controversy: an update / A controvérsia do glifosato: uma atualização

The demand for food in the world grows year after year due in part to population growth, but also to the improvement of emerging markets. Brazil is one of the largest food producers in the world. In 2017, its cereal, legume and oilseed crops totaled 238.6 million tons, 29.2% more than the year before. Much of the great increase in productivity is due to the incorporation of transgenic seeds, especially cotton, maize and soybean, which possess genes that will increase plant's adaptability to harsh soil and water conditions and, resistance to pests, but also tolerance to herbicides. Virtually, all transgenic soybeans planted in Brazil are resistant to glyphosate, the herbicide initially launched on the market by Monsanto in the 1970s under the trade name Roundup. Due to the existence of several transgenic crops tolerant to glyphosate, such as soy, wheat, corn and canola, this product is the most commercialized herbicide in the world. The use of glyphosate allows the sowing of transgenic crops immediately after application, making the planting and maintenance processes very practical. Soybeans, such as other transgenics, have biological safety already well defined, but the use of glyphosate is still an extremely controversial subject. This review presents some historical aspects of the binomial Roundup Ready soybean/glyphosate and discusses the most recent controversies about the use of glyphosate in Brazil and worldwide.(AU)

A demanda por alimentos no mundo cresce ano após ano devido em parte pelo aumento populacional, mas também pela melhoria dos mercados emergentes. O Brasil é um dos maiores produtores de alimentos do mundo. Em 2017, a safra nacional de cereais, leguminosas e oleaginosas totalizou 238,6 milhões de toneladas, 29,2% superior à obtida em 2016. Boa parte do grande aumento da produtividade se dá pela incorporação de sementes transgênicas, especialmente de algodão, milho e soja, que apresentam genes que conferem maior adaptabilidade da planta ao solo, pragas, condições hídricas, mas também conferem resistência a herbicidas. Praticamente toda a soja transgênica plantada no país é resistente ao glifosato, inicialmente lançado no mercado pela empresa Monsanto nos anos 1970 pelo nome comercial Roundup, que é hoje o herbicida mais utilizado no mundo, principalmente pela disseminação da soja e outros produtos transgênicos como trigo, milho e canola. A utilização do glifosato permite a semeadura de culturas transgênicas imediatamente após a aplicação, tornando o processo de plantio muito prático. A soja, como outros transgênicos, apresenta segurança biológica já definida, mas a utilização do glifosato ainda é um assunto extremamente controverso. Esta revisão apresenta alguns aspectos históricos do binômio soja transgênica Roundup Ready/glifosato e discute as controvérsias mais recentes sobre o uso do glifosato no Brasil e no mundo.(AU)

Morphometric alterations in hepatocytes and ultrastructural distribution of liver glycogen in pacu (Piaractus mesopotamicus Holmberg, 1887) during food restriction and refeeding

The morphometric alterations in hepatocytes and the ultrastructural distribution of tissue glycogen in pacu (Piaractus mesootamicus) were studied following food restriction and refeeding. Fish (200-300g) were allocated to control and experimental groups. The experimental group was sampled after 0, 2, 7, 30 and 60 days of food restriction and after 7 and 30 days of refeeding. The control group, which was fed daily, was sampled on the same days. The morphometric results were analyzed by ANOVA in a 2x7 (feeding x days) factorial design and the averages compared by the Tukey test. Transmission electron microscopy showed liver glycogen mobilization during food restriction. The levels of glycogen did not return to normal after up to 30 days of refeeding. There was a decrease in the cytoplasmic area and volume after seven days without food whereas changes in the nuclear area and volume appeared after two days of food restriction. Recovery of the nuclear and cytoplasmic area and volume occurred after 7 days and 30 days of refeeding, respectively. These results indicate tha liver glycogen supplies at least part of the energy requirement during food restriction in juvenile pacu. Thirty days of refeeding were not enough to re-establish the pre-restriction carbohydrate levels, probably because of the extra energy demand associated with the high metabolic rate that occurred during the compensatory process of refeeding at elevated ambient temperatures. However, the recovey seen in the morphometric parameters of the hepatocytes indicated a functional re-adjustment of the liver stimulated by the restored food supply.