γ-Linolenic acid in maternal milk drives cardiac metabolic maturation.

Birth presents a metabolic challenge to cardiomyocytes as they reshape fuel preference from glucose to fatty acids for postnatal energy production1,2. This adaptation is triggered in part by post-partum environmental changes3, but the molecules orchestrating cardiomyocyte maturation remain unknown. Here we show that this transition is coordinated by maternally supplied γ-linolenic acid (GLA), an 18:3 omega-6 fatty acid enriched in the maternal milk. GLA binds and activates retinoid X receptors4 (RXRs), ligand-regulated transcription factors that are expressed in cardiomyocytes from embryonic stages. Multifaceted genome-wide analysis revealed that the lack of RXR in embryonic cardiomyocytes caused an aberrant chromatin landscape that prevented the induction of an RXR-dependent gene expression signature controlling mitochondrial fatty acid homeostasis. The ensuing defective metabolic transition featured blunted mitochondrial lipid-derived energy production and enhanced glucose consumption, leading to perinatal cardiac dysfunction and death. Finally, GLA supplementation induced RXR-dependent expression of the mitochondrial fatty acid homeostasis signature in cardiomyocytes, both in vitro and in vivo. Thus, our study identifies the GLA-RXR axis as a key transcriptional regulatory mechanism underlying the maternal control of perinatal cardiac metabolism.S

Conteúdo alimentar em macrófitas aquáticas carnívoras: <em>Utricularia foliosa L</em>. e <em>U. hydrocarpa</em> Vahl. (Tubiflorae, Lentibulariaceae) Feeding contents of <em>Urticularia foliosa</em> L. and <em>U. hydrocarpa</em> Vahl. (Tubiflorae, Lentibulariaceae)

Neste estudo, foram considerados os aspectos qualitativos e quantitativos do conteúdo alimentar de <em>Utricularia foliosa</em> e <em>U. hydrocarpa</em> (Tubiflorae, Lentibulariaceae), para uma avaliação do impacto dessas plantas no controle de populações de organismos aquáticos. As plantas foram coletadas em dois lagos situados no entorno do Parque Estadual do Rio Doce, Estado de Minas Gerais (lagoa Amarela e lagoa da Barra). O conteúdo alimentar dos utrículos foi comparado com o perifíton (microalgas) e com o zooplâncton associados aos talos das macrófitas e ao fitoplâncton da coluna de água. Os resultados obtidos indicaram que as duas espécies de <em>Utricularia</em> utilizaram exclusivamente o recurso alimentar disponível no perifíton associado, não fazendo uso das partículas alimentares disponíveis na coluna de água. As elevadas densidades do perifíton no interior dos utrículos (<em>U. foliosa</em> = 362 a 1062org/mm² e <em>U. hydrocarpa</em> = 79 a 968 org/mm²) sugerem que essas plantas podem exercer um controle potencial sobre as populações de organismos sésseis, com pouca influência sobre as populações planctônicas limnéticas.<br>Qualitative and quantitative aspects of the feeding contents of <em>Utricularia foliosa</em> and <em>U. hydrocarpa</em> (Tubiflorae, Lentibulariaceae) were studied in order to assess the impact of these macrophytes in the control of the aquatic organisms populations. The macrophytes were collected in Lagoa Amarela and Lagoa da Barra around Parque Estadual do Rio Doce in the state of Minas Gerais. The feeding contents of the utricle were compared to the perifiton (microalgae) and zooplankton associated to the macrophytes stems and the phytoplankton free in the water column. The obtained results indicated that the two species of <em>Utricularia</em> used exclusively the periphyton and did not use the food particles available in the water column. The high densities of the periphyton inside the utricle (<em>U. foliosa</em> = 362 to 1062 org/mm² and <em>U. hydrocarpa</em> = 79 to 968 org/mm²) suggest that the plants can play a potential control on the population of sessile organisms but probably have little influence on the plankton limnetics populations