Quantitative proteomic analysis reveals altered enzyme expression profile in Zea mays roots during the early stages of colonization by Herbaspirillum seropedicae.

The use of plant growth-promoting bacteria as agricultural inoculants of plants should be encouraged because of their prominent role in biological nitrogen fixation, the increase of nutrient uptake by roots, abiotic stress mitigation, and disease control. The complex mechanisms underlying the association between plant and beneficial bacteria have been increasingly studied, and proteomic tools can expand our perception regarding the fundamental molecular processes modulated by the interaction. In this study, we investigated the changes in protein expression in maize roots in response to treatment with the endophytic diazotrophic Herbaspirillum seropedicae and the activities of enzymes related to nitrogen metabolism. To identify maize proteins whose expression levels were altered in the presence of bacteria, a label-free quantitative proteomic approach was employed. Using this approach, we identified 123 differentially expressed proteins, of which 34 were upregulated enzymes, in maize roots cultivated with H. seropedicae. The maize root colonization of H. seropedicae modulated the differential expression of enzymes involved in the stress response, such as peroxidases, phenylalanine ammonia-lyase, and glutathione transferase. The differential protein profile obtained in the inoculated roots reflects the effect of colonization on plant growth and development compared with control plants.

Short-Term Effect of Induced Alterations in Testosterone Levels on Fasting Plasma Amino Acid Levels in Healthy Young Men.

Long term effect of testosterone (T) deficiency impairs metabolism and is associated with muscle degradation and metabolic disease. The association seems to have a bidirectional nature and is not well understood. The present study aims to investigate the early and unidirectional metabolic effect of induced T changes by measuring fasting amino acid (AA) levels in a human model, in which short-term T alterations were induced. We designed a human model of 30 healthy young males with pharmacologically induced T changes, which resulted in three time points for blood collection: (A) baseline, (B) low T (3 weeks post administration of gonadotropin releasing hormone antagonist) and (C) restored T (2 weeks after injection of T undecanoate). The influence of T on AAs was analyzed by spectrophotometry on plasma samples. Levels of 9 out of 23 AAs, of which 7 were essential AAs, were significantly increased at low T and are restored upon T supplementation. Levels of tyrosine and phenylalanine were most strongly associated to T changes. Short-term effect of T changes suggests an increased protein breakdown that is restored upon T supplementation. Fasting AA levels are able to monitor the early metabolic changes induced by the T fluctuations.