Loss of major nutrient sensing and signaling pathways suppresses starvation lethality in electron transport chain mutants

The electron transport chain (ETC) is a well-studied and highly conserved metabolic pathway that produces ATP through generation of a proton gradient across the inner mitochondrial membrane coupled to oxidative phosphorylation. ETC mutations are associated with a wide array of human disease conditions and to aging-related phenotypes in a number of different organisms. In this study, we sought to better understand the role of the ETC in aging using a yeast model. A panel of ETC mutant strains that fail to survive starvation was used to isolate suppressor mutants that survive. These suppressors tend to fall into major nutrient sensing and signaling pathways, suggesting that the ETC is involved in proper starvation signaling to these pathways in yeast. These suppressors also partially restore ETC-associated gene expression and pH homeostasis defects, though it remains unclear if these phenotypes directly cause the suppression or are simply effects. This work further highlights the complex cellular network connections between metabolic pathways and signaling events in the cell, and their potential roles in aging and age-related diseases.

Nutrient Digestibility and Digestive Enzyme Activity in Fringe Lipped Carp, Labeo fimbriatus (Bloch, 1795), Fed Diets Containing Cottonseed Meal

Advanced fingerlings of Labeo fimbriatus (Bloch, 1795) were reared in aerated indoor plastic tanks to elucidate the dry matter and nutrient digestibility of cottonseed meal (CSM) in the feed. The fish were fed isocaloric formulated diets containing CSM replacing the main ingredients – groundnut cake and rice bran of the control diet at 10, 20, 30 and 40 % levels. Total dry matter digestibility and major nutrient digestibility were estimated using acid insoluble ash as the marker. In general, the digestibility of dry matter, protein, fat, and nitrogen-free extract was higher in CSM incorporated diets than the control diet. While the dry matter and nitrogen-free extract digestibility values were highest at 40 % CSM incorporation level, those for protein and fat digestibility were highest in 30 % and 10 % levels, respectively, showing an apparent reduction thereafter. The incorporation of CSM had a stimulatory effect on most of the intestinal digestive enzymes tested. Fish fed 20 % CSM diet recorded the highest activity of total protease and carboxypeptidases while those fed 30 % CSM diet had highest trypsin and amylase activities; all showing reducing trend consequently. In the case of hepatopancreas, the reducing trend in the activities of protease, chymotrypsin, carboxypeptidase A, and lipase observed with increased incorporation levels of CSM was significant (P < 0.05) and the reduction in the activities of trypsin, amylase and cellulase in CSM fed fish was not significant (P > 0.05). The study indicates the possibility of incorporation of CSM in the diet of L. fimbriatus up to 40 % level without affecting nutrient digestibility.

The inhibition of biodegradation on building limestone by plasma etching

Plasma etching is an innovative technique that has been recently applied in the cleaning of soiled archaeological objects. This research investigated the use of low-pressure plasma etching in cleaning microbial contaminations on an oolitic limestone from an UNESCO World Heritage listed monument: the Batalha Monastery in Central Portugal. The cleaning effect was assessed by FTIR, SEM, optical microscope, and cell viability index measurement. Experimental work suggests that plasma discharge can cause rupture in the microbial cell structures and is helpful in removing microorganisms from the surface of the stone. At the macroscopic level, detachment of microbial crust was also observed in plasma etched bio-deteriorated limestone surfaces. Furthermore, plasma etching can inhibit the microbial growth by decomposing and eliminating the sugar-containing compounds on the limestones, thus eliminating a major nutrient supply for microbial metabolism and reproduction. Plasma etching can therefore be regarded as a fast and eco-friendly conservation tool for stone heritage architecture to prevent/reduce the onset of bio-colonization and biodegradation.

Sulfated host glycan recognition by carbohydrate sulfatases of the human gut microbiota

The vast microbial community that resides in the human colon, termed the human gut microbiota, performs important roles in maintaining host health. Sulfated host glycans comprise both a major nutrient source and important colonisation factors for this community. Carbohydrate sulfatases remove sulfate groups from glycans and are essential in many bacteria for the utilisation of sulfated host glycans. Additionally, carbohydrate sulfatases are also implicated in numerous host diseases, but remain some of the most understudied carbohydrate active enzymes to date, especially at the structural and molecular level. In this work, we analyse 7 carbohydrate sulfatases, spanning 4 subfamilies, from the human gut symbiont Bacteroides thetaiotaomicron, a major utiliser of sulfated host glycans, correlating structural and functional data with phylogenetic and environmental analyses. Together, these data begin to fill the knowledge gaps in how carbohydrate sulfatases orchestrate sulfated glycan metabolism within their environment.

Sulfated host glycan recognition by carbohydrate sulfatases of the human gut microbiota

The vast microbial community that resides in the human colon, termed the human gut microbiota, performs important roles in maintaining host health. Sulfated host glycans comprise both a major nutrient source and important colonisation factors for this community. Carbohydrate sulfatases remove sulfate groups from glycans and are essential in many bacteria for the utilisation of sulfated host glycans. Additionally, carbohydrate sulfatases are also implicated in numerous host diseases, but remain some of the most understudied carbohydrate active enzymes to date, especially at the structural and molecular level. In this work, we analyse 7 carbohydrate sulfatases, spanning 4 subfamilies, from the human gut symbiont Bacteroides thetaiotaomicron, a major utiliser of sulfated host glycans, correlating structural and functional data with phylogenetic and environmental analyses. Together, these data begin to fill the knowledge gaps in how carbohydrate sulfatases orchestrate sulfated glycan metabolism within their environment.

Diversity and Distribution of Ciliated Protozoans on the Mangrove Leaf Litters in a Tropical Mangrove Ecosystem

Litter production and its decomposition is a major nutrient source for mangrove ecosystems. The bacterivores nature of ciliates in mangrove leaf litters, increase the mineralization and making nutrients more available to the next trophic level. This study was conducted to access the species composition, diversity and abundance of ciliates in mangrove leaf litters. Monthly samples were collected for one year (June 2014 – May 2015) from ten selected stations. Eight physicochemical variables such as temperature, dissolved oxygen, pH, conductivity, chloride, sulfate, nitrate, and phosphate were also monitored during the study. Taxonomic studies recorded 115 species of ciliates belonging to 16 subclasses, among them Peritricha represent the subclass having the maximum species number and abundance followed by Suctoria. Vorticella companula records the maximum abundance and dominance index followed by Euplotes minuta. Analyzing the seasonal distribution of ciliates, a maximum number of species were recorded during post-monsoon and minimum during monsoon. The study establishes the distributional difference, diversity and abundance of peritrich ciliates on mangrove leaf litters according to seasonal fluctuations. Multivariate statistical analysis of different environmental parameters regarding species diversity and abundance of mangrove ciliates, it was found that the environmental parameters have an impact on the distribution and diversity of ciliates in mangrove leaf litters. The study signifies the importance of leaf litters and environmental variables in the dynamics of ciliates composition and abundance.

Mechanistic insight into DsyB/DSYB, key enzymes in marine dimethylsulfoniopropionate synthesis

Marine algae and bacteria produce eight billion tonnes of the organosulfur molecule dimethylsulfoniopropionate (DMSP) in Earth’s surface oceans every year. DMSP is an anti-stress compound and, once released into the environment, a major nutrient, signalling molecule and source of climate-active gases. The methionine transamination pathway for DMSP synthesis is used by most known DMSP-producing algae and bacteria. The S-directed S-adenosylmethionine-dependent methyltransferase (SAM-MT) 4-methylthio-2-hydroxybutyrate (MTHB) S-methyltransferase, encoded by the dsyB/DSYB gene, is the key enzyme of this pathway, generating S-adenosylhomocysteine (SAH) and 4-dimethylsulfonio-2-hydroxybutyrate (DMSHB). dsyB/DSYB, present in most DMSP-producing bacteria and haptophyte and dinoflagellate algae with the highest known DMSP concentrations, is shown to be far more abundant and transcribed in marine environments than any other known DMSP synthesis pathway S-methyltransferase gene. Furthermore, we demonstrate in vitro activity of the bacterial DsyB enzyme from Nisaea denitrificans, and provide its crystal structure in complex with SAM and SAH-MTHB, which together provide the first mechanistic insights into a DMSP synthesis enzyme. Structural and mutational analyses imply that DsyB adopts a novel mechanism, distinct from any previously reported SAM-MT, in which the DsyB residue Tyr142 activates the sulfur atom of MTHB for nucleophilic attack on the SAM methyl group. Sequence analysis suggests that this mechanism is common to all bacterial DsyB enzymes and also, importantly, eukaryotic DSYB enzymes from e.g., algae that are the major DMSP producers in Earth’s surface oceans.

Patterns of Nutrient Intake in Relation to Sarcopenia and Its Components

Background: Despite the associations between individual nutrients and sarcopenia, we are aware of no information about the link between patterns of nutrient intake and odds of sarcopenia and its components. The present study aimed to examine the association between nutrient-based dietary patterns and sarcopenia and its components among the Iranian adult population.Methods: In this population-based, cross-sectional study, we enrolled 300 elderly adults (150 men and 150 women) aged ≥55 years by using a cluster random sampling method. Dietary intakes of the study population were assessed using a validated food frequency questionnaire. Principal component analysis was conducted to derive nutrient patterns based on a daily intake of 33 nutrients. Muscle mass, muscle strength, and gait speed were measured according to standard methods. Sarcopenia and its components were defined based on the European Working Group on Sarcopenia.Results: Three major nutrient-based dietary patterns were identified: (1) the “pro-vit pattern” that was high in pantothenic (B5), cobalamin (B12), calcium, protein, phosphor, riboflavin (B2), zinc, cholesterol, saturated fat, folate, niacin (B3), selenium, vitamin D, vitamin K, and vitamin A; (2) the “anti-inflammatory” pattern, which was rich in polyunsaturated fat, monounsaturated fat, copper, vitamin E, omega-3, magnesium, iron, pyridoxine (B6), sodium, and caffeine; and (3) the “carbo-vit” patternm which is characterized by high intake of fructose, glucose, dietary fiber, biotin, potassium, thiamin (B1), vitamin C, and chromium. After adjusting for confounders, subjects in the top tertile of the anti-inflammatory pattern had lower odds of sarcopenia (OR 0.25; 95% CI 0.10–0.63) and low muscle strength (OR: 0.46; 95% CI: 0.22–0.96) than those in the bottom tertile. Greater adherence to the carbo-vit pattern was inversely associated with the odds of low gait speed (OR: 0.46; 95% CI: 0.235–0.93).Conclusion: Major nutrient-based dietary patterns were significantly associated with sarcopenia and its components. Further studies are required to confirm our findings.