Intestinal microbiota changes are associated with the development of obesity. However, studies in humans have generated conflicting results due to high inter-individual heterogeneity in terms of diet, age, and hormonal factors, and the largely unexplored influence of gender. In this work, we aimed to identify differential gut microbiota signatures associated with obesity, as a function of gender and changes in body mass index (BMI). Differences in the bacterial community structure were analyzed by 16S sequencing in 39 men and 36 post-menopausal women, who had similar dietary background, matched by age and stratified according to the BMI. We observed that the abundance of the Bacteroides genus was lower in men than in women (P 33. In fact, the abundance of this genus decreased in men with an increase in BMI (P<0.001, Q<0.001). However, in women, it remained unchanged within the different ranges of BMI. We observed a higher presence of Veillonella (84.6% vs. 47.2%; X² test P = 0.001, Q = 0.019) and Methanobrevibacter genera (84.6% vs. 47.2%; X² test P = 0.002, Q = 0.026) in fecal samples in men compared to women. We also observed that the abundance of Bilophila was lower in men compared to women regardless of BMI (P = 0.002, Q = 0.041). Additionally, after correcting for age and sex, 66 bacterial taxa at the genus level were found to be associated with BMI and plasma lipids. Microbiota explained at P = 0.001, 31.17% variation in BMI, 29.04% in triglycerides, 33.70% in high-density lipoproteins, 46.86% in low-density lipoproteins, and 28.55% in total cholesterol. Our results suggest that gut microbiota may differ between men and women, and that these differences may be influenced by the grade of obesity. The divergence in gut microbiota observed between men and women might have a dominant role in the definition of gender differences in the prevalence of metabolic and intestinal inflammatory diseases.

Summary: Nitrate is an essential nutrient, and is involved in many adaptive responses of plants, such as localized proliferation of roots, flowering or stomatal movements. How such nitrate‐specific mechanisms are regulated at the molecular level is poorly understood. Although the Arabidopsis ANR1 transcription factor appears to control stimulation of lateral root elongation in response to nitrate, no regulators of nitrate assimilation have so far been identified in higher plants. Legume‐specific symbiotic nitrogen fixation is under the control of the putative transcription factor, NIN, in Lotus japonicus. Recently, the algal homologue NIT2 was found to regulate nitrate assimilation. Here we report that Arabidopsis thaliana NIN‐like protein 7 (NLP7) knockout mutants constitutively show several features of nitrogen‐starved plants, and that they are tolerant to drought stress. We show that nlp7 mutants are impaired in transduction of the nitrate signal, and that the NLP7 expression pattern is consistent with a function of NLP7 in the sensing of nitrogen. Translational fusions with GFP showed a nuclear localization for the NLP7 putative transcription factor. We propose NLP7 as an important element of the nitrate signal transduction pathway and as a new regulatory protein specific for nitrogen assimilation in non‐nodulating plants.

Context: Gut microbiota, which acts collectively as a fully integrated organ in the host metabolism, can be shaped by long-term dietary interventions after a specific diet. Objective: The aim was to study the changes in microbiota after 1 year's consumption of a Mediterranean diet (Med diet) or a low-fat, high-complex carbohydrate diet (LFHCC diet) in an obese population. Design: Participants were randomized to receive the Med diet (35% fat, 22% monounsaturated) and the LFHCC diet (28% fat, 12% monounsaturated). Setting and Participants: The study was conducted in 20 obese patients (men) within the Coronary Diet Intervention With Olive Oil and Cardiovascular Prevention (CORDIOPREV) study, an ongoing prospective, randomized, opened, controlled trial in patients with coronary heart disease. Main Outcome Measure: We evaluated the bacterial composition and its relationship with the whole fecal and plasma metabolome. Results: The LFHCC diet increased the Prevotella and decreased the Roseburia genera, whereas the Med diet decreased the Prevotella and increased the Roseburia and Oscillospira genera (P = .028, .002, and .016, respectively). The abundance of Parabacteroides distasonis (P = .025) and Faecalibacterium prausnitzii (P = .020) increased after long-term consumption of the Med diet and the LFHCC diet, respectively. The changes in the abundance of 7 of 572 metabolites found in feces, including mainly amino acid, peptide, and sphingolipid metabolism, could be linked to the changes in the gut microbiota. Conclusions: Our results suggest that long-term consumption of the Med and LFHCC diets exerts a protective effect on the development of type 2 diabetes by different specific changes in the gut microbiota, increasing the abundance of the Roseburia genus and F. prausnitzii, respectively.

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut–brain axis, given the relevance of these factors in the development of metabolic diseases.