Jania adhaerens Primes Tomato Seed against Soil-Borne Pathogens

Managing soil-borne pathogens is complex due to the restriction of the most effective synthetic fungicides for soil treatment. In this study, we showed that seed priming with Jania adhaerens water-soluble polysaccharides (JA WSPs) was successful in protecting tomato plants from the soil-borne pathogens Rhizoctonia solani, Pythium ultimum, and Fusarium oxysporum under greenhouse conditions. WSPs were extracted from dry thallus by autoclave-assisted method, and the main functional groups were characterized by using FT-IR spectroscopy. WSPs were applied by seed treatment at 0.3, 0.6 and 1.2 mg/mL doses, and each pathogen was inoculated singly in a growing substrate before seeding/transplant. Overall, WSPs increased seedling emergence, reduced disease severity and increased plant development depending on the dose. Transcriptional expression of genes related to phenylpropanoid, chlorogenic acid, SAR and ISR pathways, and chitinase and beta-1,3 glucanase activities were investigated. Among the studied genes, HQT, HCT, and PR1 were significantly upregulated depending on the dose, while all doses increased PAL and PR2 expression as well as beta-1,3 glucanase activity. These results demonstrated that, besides their plant growth promotion activity, JA WSPs may play a protective role in triggering plant defense responses potentially correlated to disease control against soil-borne pathogens

Evaluating Ecklonia maxima water-soluble polysaccharides as a growth promoter of tomato seedlings and resistance inducer to Fusarium wilt

Alternatives to chemicals for plant management are increasingly used to reduce environmental pollution. Seed treatment with natural products may act as a priming effect by stimulating seedling growth and plant defence responses against fungal pathogens. In this framework, algae produce a wide variety of bioactive metabolites, which can be used in agriculture as biofertilizers or biostimulants. The purpose of this study was to investigate the possible role of water-soluble polysaccharides (WSPs) from the brown alga Ecklonia maxima applied on tomato seed in enhancing plant growth and inducing resistance to Fusarium oxysporum via modulation of multiple physiological parameters and metabolic pathways. Here, we first characterized the E. maxima WSPs by FT-IR spectroscopy, and then we tested the WSPs as growth promoters on tomato seedlings, and the physiological and defence responses of plants during pathogen infection. We found that WSP seed treatment without pathogen challenge stimulated seedling height and root growth by 24.5 and 62.9%, respectively. Under pathogen infection, plants exhibited long-lasting resistance against F. oxysporum until 46 days after seed treatment. The metabolic changes associated with resistance to Fusarium wilt in plant roots were related to an increase in phenols, flavonoids and protein contents as well as a higher chitinase and beta-1,3-D-glucanase enzyme activity. Moreover, PR1a, PR3 and other defence gene expressions were significantly increased. Resistance to F. oxysporum as a result of WSP seed treatment was also supported by FT-IR analysis of tomato roots. Infected roots showed a decrease in the relative intensity of the bands due to the syringyl ring and amide I and amide II in proteins. In contrast, WSP treatment alone and in the presence of the pathogen exhibited a spectral profile similar to that of the control. This research emphasizes the potential role of algal polysaccharides applied by seed treatment in promoting seedling growth and priming plant resistance against soil-borne pathogens

Polyamine supplementation reduces DNA damage in adipose stem cells cultured in 3-D

According to previous research, natural polyamines exert a role in regulating cell committment and differentiation from stemness during skeletal development. In order to assess whether distinct polyamine patterns are associated with different skeletal cell types, primary cultures of stem cells, chondrocytes or osteoblasts were dedicated for HPLC analysis of intracellular polyamines. Spermine (SPM) and Spermidine (SPD) levels were higher in adipose derived stem cells (ASC) compared to mature skeletal cells, i.e. chondrocytes and osteoblasts, confirming the connection of polyamine content with stemness. To establish whether polyamines can protect ASC against oxidative DNA damage in a 3-D differentiation model, the level of gamma H2AX was measured by western blot, and found to correlate with age and BMI of patients. Addition of either polyamine to ASC was able to hinder DNA damage in the low micromolecular range, with marked reduction of gamma H2AX level at 10 mu M SPM and 5 mu M SPD. Molecular analysis of the mechanisms that might underlie the protective effect of polyamine supplementation evidences a possible involvement of autophagy. Altogether, these results support the idea that polyamines are able to manage both stem cell differentiation and cell oxidative damage, and therefore represent appealing tools for regenerative and cell based applications

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Metabolic Flexibility for Metabolic Health: Role of Nutrition and Nutraceuticals

Both lifespan and health span are influenced by nutrition, with nutritional interventions proving to be robust across a wide range of species. However, mechanisms by which nutrients and nutritional status may affect health span are not fully understood. Both health span and life span are closely linked to metabolic health and this condition mainly depends on metabolic flexibility. Metabolic flexibility is a term coined by Kelley et al. [1], and is conceptually defined as the ability to efficiently adapt metabolism by substrate sensing, trafficking, storage, and utilization, in response to availability and requirement of nutrients as well as by physical activity. In health conditions, metabolic flexibility, i.e. metabolic plasticity, is essential to maintain energy homeostasis. As example, skeletal muscle of lean or physically active individuals showed a remarkable ability to adapt fuel preference to nutrient supply and was therefore designated as metabolically flexible. Upon consumption of a high-fat diet, lean subjects were able to increase Fatty Acid Oxidation (FAO) at the expense of glucose, whereas obese individuals were not [2]. Lean or physically active individuals also showed an increased expression of genes involved in fatty acid transport and oxidation compared with little or no change in their obese counterparts [3]. The ability to shift fuel source oxidation from carbohydrates to fats is generally related to metabolic health. Studies on mice showed that metabolic flexibility correlates with a healthy Respiratory Exchange Ratio (RER) resulting from the circadian shift between carbohydrate (value of 1.0) to lipid metabolism (value of 0.7) [4]. Mitochondrial dysfunction lead to a cellular shift toward a glycolytic phenotype, which is intimately linked, to a sedentary lifestyle and senescence. Metabolic flexibility is negatively correlated with aging and is disrupted in some pathological conditions, as in ectopic lipid accumulation which is causally linked to insulin resistance, in the context of obesity and metabolic syndrome [5]. Insulin-resistant obese patients manifest a lesser reliance on fatty acid oxidation compared with lean individuals and do not show increased fatty acid oxidation after fasting or reduced fatty acid oxidation after insulin infusion. Because of their inadequate responses to metabolic challenges, these patients are named \u201cmetabolically inflexible\u201d [6]. Metabolic inflexibility is a hallmark of many age-related metabolic diseases but also plays a central role in, for instance, cancer and immune metabolism diseases. Conversely, metabolic flexibility is enhanced by lifestyle interventions including exercise training and controlled Calorie Restriction (CR), which are able to reduce obesity, visceral fat deposit and ectopic lipid accumulation [7]. Exercise, in particular, is a principal preventive strategy to improve metabolic flexibility at all ages and prolong healthy aging [8]. These interventions are able to favor mitochondrial function and improve substrate switching and metabolic health. Molecular and signaling pathways drive metabolic flexibility and often serve as metabolic sensors able to respond to different nutritional conditions or exercise. Pathways involved in metabolic flexibility are those mediated by Mammalian Target of Rapamycin (mTOR) and insulin/insulin-like Growth Factor-1 (IGF-1) which are generally stimulated in fed conditions, and by pathways activated by fasting, involving AMP-Activated Protein Kinase (AMPK), NAD+- dependent sirtuin (SIRT) deacetylases and PPAR\u3b3 coactivator 1-a PGC1a) (see ref 11 for a review). Main sensor of low energy levels is AMPK, which mediates one of the \u201cchief\u201d step of metabolic flexibility represented by \u201cglucose-fatty acid cycle\u201d [9]. This step states that high glucose availability suppresses oxidation of fatty acids and vice versa [5]. In particular, during CR, the rise in AMP/ATP activates AMPK, which inhibits Acetyl-Coenzyme a Carboxylase (ACC), thus stimulating fatty acid uptake by the mitochondria via Carnitine- Palmitoyl Transferase 1 (CPT-1) and increasing FAO. In parallel, during CR, the increase of NAD+ concentrations stimulates nuclear/ cytoplasmic-localized SIRT1 and mitochondrial SIRT3 activity and leads to protein deacetylation and improved mitochondrial function. There is a reciprocal interplay between AMPK and SIRT, which contributes to metabolic adaptations during fasting conditions [10] as well as during aerobic exercise. This interplay leads to increased transcription, translation, and activity of the transcriptional coactivator PGC1a which is a main mediator of mitochondrial biogenesis and regulator of exercise-induced adaptations in the capacity of oxidative phosphorylation in skeletal muscle [11,12]. In the last years many food-derived natural compounds, also named nutraceuticals have been investigated in relation to their effects on most of the nutrient sensing pathways activated by CR and physical exercise, and potentially related to longevity and health span [13- 15]. However, in our opinion there are only few controlled studies on the effects of single dietary components on biochemical pathways and enzymes able to improve metabolic flexibility. As example, one relevant aspect might be related to prevention of ectopic intracellular lipid accumulation. At this purpose biochemical studies on nutritional modulation of enzymes involved in substrate switching such as Pyruvate Dehydrogenase (PDH) and PDH kinase 4 (PDK4) as well as in pathways leading to cytosolic acetyl-coenzyme A (acetyl-CoA) accumulation could be of great interest. Nucleo-cytosolic acetyl-CoA has emerged as a central signaling node used to coordinate metabolic flexibility in response to a changing of nutritional status. In fact, cells utilize acetyl-CoA levels to integrate nutrient status with energy levels to ensure the proper funneling of substrate toward energy production or storage. In cytosol acetyl-CoA is generated by the enzyme ATP Citrate Lyase (ACLY) which catalyzes the cleavage of citrate to oxaloacetate and acetyl-CoA, a critical reaction linking cellular glucose metabolism and lipogenesis. Accumulation of acetyl-CoA in cytosol also favors protein acetylation and inhibits autophagy with a negative impact for metabolic health. Recently the involvement of ACLY in the progression and development of various chronic diseases has been comprehensively described [16]. Preclinical studies and clinical randomized trials showed the importance of ACLY activity in metabolism, supporting its inhibition as a potential therapeutic approach to treat atherosclerotic cardiovascular disease, nonalcoholic fatty liver disease and other metabolic disorders [17]. Among nutraceuticals Garcinia cambogia, which contains Hydroxycitric Acid (HCA) has been reported to play a role in inhibiting the enzyme ACLY [14]. However, the safety of this plant extract has been highly questioned [18]. In our opinion further studies are needed that address more exhaustive role of nutrition and nutraceuticals on pathways involved in regulation of metabolic flexibility as well as on any other process affecting cellular metabolic health

Molecular mechanisms linking nutrition to metabolic homeostasis: An overview picture of current understanding

Increasing evidence supports the notion that in humans many pathological conditions including obesity, metabolic syndrome, and type 2 diabetes are closely related to the amount and quality of each nutritional component and to an impairment of the metabolic homeostatic mechanisms of their utilization. Cell signaling pathways that sense the availability of nutrients and the energy status of the cells communicate with signaling pahways triggered by hormones and growth factors to coordinately regulate whole-body metabolic homeostasis. The aim of this review is to provide an overview picture of current knowledge about the main molecular mechanisms that connect nutritional status, hormones, and nutrient levels with gene expression, metabolic homeostasis, and nutrient sensing. We recapitulate molecular mechanisms governing fuel selection between glucose and fatty acids in different nutritional conditions, highlighting metabolic flexibility as mechanism to ensure metabolic health. Disrupted metabolic flexibility, or metabolic inflexibility, is associated with many pathological conditions including metabolic syndrome, type 2 diabetes mellitus, and cancer. We also describe how macronutrients that can be used as energy sources may reciprocally modulate their own metabolism as well as directly interact with transcriptional factors, nutrient sensors and nutrient sensing pathways in order to achieve metabolic homeostasis