scholarly journals Enhanced microbial nitrogen transformations in association with intertidal macrobiota

2018 ◽  
Author(s):  
Catherine A. Pfister ◽  
Mark A. Altabet
Keyword(s):  
Microbial Activity ◽  
Nitrate Reduction ◽  
Phosphorus Uptake ◽  
Ammonium Oxidation ◽  
Nitrogen Transformations ◽  
Marine Animals ◽  
Microbial Nitrogen ◽  
Direct Association ◽  
Inert Substrate

Abstract. Microbial nitrogen processing in direct association with marine animals and seaweeds is poorly understood. Macrobiota supply a substrate for microbes to reside, and a source of excreted nitrogen and dissolved organic carbon (DOC). We tested the role of a mussel (Mytilus californianus), a red alga (Prionitis sternbergii) and an inert substrate for microbial activity using enclosed chambers and enriched ammonium and nitrate. Chambers with seawater from the same environment served as a control. We found that mussels and Prionitis elevated ammonium oxidation and nitrate reduction two orders of magnitude over that of seawater, while the effect of simply an inert substrate had relatively little effect. Extrapolating to a square meter of shoreline, microbial activity associated with mussels could oxidize 2.5 mmol of ammonium and reduce per 1.2 mmol of nitrate per day. A square meter of seaweed could produce even higher rates, at 135.2 and 320.5 mmol per day for nitrification and nitrate reduction, respectively. Seawater collected from the shore versus 2–5 km offshore showed no difference in ammonium oxidation or nitrate reduction. Microbial nitrogen metabolism associated with mussels did not change whether we measured it at night or during the day. When we experimentally added DOC (glucose) as a carbon source, there was no change to nitrification rates. Added DOC did increase DIN and phosphorus uptake, indicating that elevating the concentration of DOC stimulated heterotrophic microbial activity, and suggests potential competition for DIN between heterotrophic and chemolithotrophic microbes and their seaweed hosts. Our results indicate that microbes in direct association with coastal animals and seaweeds greatly enhance nitrogen processing, and likely provide a template for a diversity of ecological interactions.

scholarly journals Enhanced microbial nitrogen transformations in association with macrobiota from the rocky intertidal

2019 ◽  
Vol 16 (2) ◽  
pp. 193-206 ◽  
Author(s):  
Catherine A. Pfister ◽  
Mark A. Altabet
Keyword(s):  
Microbial Activity ◽  
Inorganic Nitrogen ◽  
Phosphorus Uptake ◽  
Red Alga ◽  
Time Of Day ◽  
Ammonium Oxidation ◽  
Nitrogen Transformations ◽  
Marine Animals ◽  
Microbial Nitrogen ◽  
Direct Association

Abstract. Microbial nitrogen processing in direct association with marine animals and seaweeds is poorly understood. Microbes can both attach to the surfaces of macrobiota and make use of their excreted nitrogen and dissolved organic carbon (DOC). We tested the role of an intertidal mussel (Mytilus californianus) and red alga (Prionitis sternbergii), as well as inert substrates for microbial activity using enclosed chambers with seawater labeled with 15N-enriched ammonium and nitrate. Chambers with only seawater from the same environment served as a control. We found that 3.21 nmol of ammonium per gram of dry mass of mussel, on average, was oxidized per hour, while 1.60 nmol of nitrate was reduced per hour. Prionitis was associated with the oxidation of 1.50 nmol of ammonium per gram of wet mass per hour, while 1.56 nmol of nitrate was reduced per hour. Inert substrates produced relatively little change compared to seawater alone. Extrapolating to a square meter of shoreline, microbial activity associated with mussels could oxidize 2.5 mmol of ammonium and reduce per 1.2 mmol of nitrate per day. A square meter of seaweed could oxidize 0.13 mmol ammonium per day and reduce the same amount of nitrate. Seawater collected proximal to the shore versus 2–5 km offshore showed no difference in ammonium oxidation or nitrate reduction. Microbial nitrogen metabolism associated with mussels was not influenced by the time of day. When we experimentally added DOC (glucose) as a carbon source to chambers with the red alga and inert substrates, no change in nitrification rates was observed. Added DOC did increase dissolved inorganic nitrogen (DIN) and phosphorus uptake, indicating that DOC addition stimulated heterotrophic microbial activity, and suggests potential competition for DIN between heterotrophic and chemolithotrophic microbes and their seaweed hosts. Our results demonstrate that microbes in direct association with coastal animals and seaweeds greatly enhance nitrogen processing and likely provide a template for a diversity of ecological interactions.

scholarly journals Oxygen and light determine the pathways of nitrate reduction in a highly saline lake

2020 ◽  
Author(s):  
Nicolás Valiente ◽  
Franz Jirsa ◽  
Thomas Hein ◽  
Wolfgang Wanek ◽  
Patricia Bonin ◽  
...  
Keyword(s):  
Nitrate Reduction ◽  
Environmental Gradients ◽  
Nitrate Removal ◽  
Hypersaline Lake ◽  
N2o Emissions ◽  
Ammonium Oxidation ◽  
Lake Ecosystems ◽  
N Removal ◽  
Mesocosm Experiments

Abstract. Nitrate (NO3−) removal from aquatic ecosystems involves several microbially mediated processes including denitrification, dissimilatory nitrate reduction to ammonium (DNRA), and anaerobic ammonium oxidation (anammox) regulated by slight changes in environmental gradients. Saline lakes are prone to the accumulation of anthropogenic contaminants, making them highly vulnerable environments to NO3− pollution. We investigated nitrate removal pathways in mesocosm experiments using lacustrine, undisturbed, organic-rich sediments from Pétrola Lake (Spain), a highly saline waterbody subject to anthropogenic NO3− pollution. We used the revised 15N-isotope pairing technique (15N-IPT) to determine NO3− sink processes. Our results demonstrate the coexistence of denitrification, DNRA, and anammox processes, and their contribution was determined by environmental conditions (oxygen and light). DNRA and N2O-denitrification were the dominant nitrogen (N) removal pathways when oxygen and/or light were present (up to 82 %). In contrast, anoxia and darkness promoted NO3− reduction by DNRA (52 %) and N loss by anammox (28 %). Our results highlight the role of coupled DNRA-anammox, as yet has never been investigated in hypersaline lake ecosystems. We conclude that anoxia and darkness favored DNRA and anammox processes over denitrification and therefore reduce N2O emissions to the atmosphere.

scholarly journals Role of SES on the association between childhood parental death and adulthood suicidal ideation: a mediation analysis using longitudinal dataset in South Korea

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Jaehong Yoon ◽  
Ja Young Kim ◽  
Ji-Hwan Kim ◽  
Seung-Sup Kim
Keyword(s):  
Suicidal Ideation ◽  
South Korea ◽  
Mediation Analysis ◽  
Household Income ◽  
Parental Death ◽  
Middle Adulthood ◽  
Late Adulthood ◽  
Mediating Role ◽  
Direct Association

Abstract Background We sought to examine the association between childhood experience of parental death (CEPD) and adulthood suicidal ideation, and the mediating role of adulthood SES in the association. Methods We analyzed a nationally representative dataset of 8609 adults from the Korea Welfare Panel Study, which is a longitudinal cohort dataset in South Korea. CEPD was measured using a question: “During your childhood (0-17 years old), have you experienced the death of parents?” We classified responses of CEPD during 2006–2011 into ‘yes,’ and the others into ‘no.’ Suicidal ideation over the past year was assessed annually during 2012–2019. As a potential mediator, adulthood educational attainment and household income in 2011 were included in the analysis. Logistic regression was applied to examine the association of CEPD with adulthood suicidal ideation across age groups (early adulthood, 19–39 years old; middle adulthood, 40–59 years old; late adulthood, ≥60 years old), after excluding people who reported lifetime suicidal ideation in 2011. Causal mediation analysis using a parametric regression model was applied to examine the mediating role of adulthood SES in the association between CEPD and adulthood suicidal ideation. Results After adjusting for potential confounders including childhood SES, CEPD was significantly associated with adulthood suicidal ideation among the late adulthood group (OR: 1.43; 95% CI: 1.13–1.81), while the association was not statistically significant among the early; and middle adulthood groups. In mediation analysis of adulthood household income, both indirect association (ORNIE: 1.05; 95% CI: 1.02–1.09) and direct association (ORNDE: 1.37; 95% CI: 1.09–1.73) were statistically significant among the late adulthood group. In the mediation analysis of adulthood education attainment among the late adulthood, only a direct association was statistically significant (ORNDE: 1.43; 95% CI: 1.14–1.80). Conclusions These results suggest that CEPD could be a risk factor for adulthood suicidal ideation. Furthermore, the findings imply that income security policy might be necessary to reduce suicide among the late adulthood group.

The role of chemotaxis and efflux pumps on nitrate reduction in the toxic regions of a ciprofloxacin concentration gradient

2021 ◽  
Author(s):  
Reinaldo E. Alcalde ◽  
Christopher M. Dundas ◽  
Yiran Dong ◽  
Robert A. Sanford ◽  
Benjamin Keith Keitz ◽  
...  
Keyword(s):  
Concentration Gradient ◽  
Nitrate Reduction ◽  
Efflux Pumps

scholarly journals Evaluation of corpora amylacea in refractory epilepsy

2020 ◽  
Vol 105 (105(810)) ◽  
pp. 103-107
Author(s):  
J. García-Fernández ◽  
M. M. García-Fernández ◽  
M. García-Fernández ◽  
C. J. Acal-González ◽  
R. García-del-Moral ◽  
...  
Keyword(s):  
Histological Analysis ◽  
Refractory Epilepsy ◽  
Age Of Onset ◽  
Clinical Parameters ◽  
Corpora Amylacea ◽  
Significant Evidence ◽  
Direct Association ◽  
Pas Staining ◽  
Hematoxylin Eosin

Objectives: The purpose of this study is to check whether there is or not a relationship between CoA density and different clinical parameters of the disease established. Compare the assessment of CoA with Hematoxylin-Eosin technique against PAS staining. It is also intended to check if it exists a relationship between hippocampal CoA density and Nestine overexpression. Methods: Histological analysis of 14 patients. For the counting of the CoA, raw scores were used interchangeably, as well as discretized values on a semi-quantitative scale according to Cherian et al. criteria. The modified Engel scale was used to measure post-surgical evolution. Results: The proportion of CoA in the hippocampus matches the proportion found in different studies: 64.3%. At α=0.05, there is significant evidence to observe that the counting is different depending on the type of staining used in the slides. The average number of CoA is higher with the PAS. It is seen that the density of CoA in the hippocampus and cortex is directly related to its density in parahypocampal structures. With regard to the relation between CoA density and age of onset, there are signs of significance. As well as in the post-surgical evolution. With regard to the duration of the crisis period, was found that both variables are independent. Finally, it is observed that there is a direct association between Nestine overexpression and hippocampal CoA density. Conclusion: In patients with Refractory Epilepsy (ER), CoA presence is commonly verified, with a better evaluation with PAS staining. Respectfully to the relation between CoA density and age of onset, there are signs of significance, as well as post-surgical evolution with the modified Engel scale. It would be convenient to continue with the investigations in this field to contrast the role of CoA in ER.

scholarly journals Rare microbes from diverse Earth biomes dominate community activity

2019 ◽  
Author(s):  
Rohan Sachdeva ◽  
Barbara J. Campbell ◽  
John F. Heidelberg
Keyword(s):  
Community Structure ◽  
Microbial Activity ◽  
Ecosystem Function ◽  
Total Activity ◽  
Reaction Rates ◽  
Community Activity ◽  
Crucial Component ◽  
Tightly Coupled ◽  
The Relationship

AbstractMicrobes are the Earth’s most numerous organisms and are instrumental in driving major global biological and chemical processes. Microbial activity is a crucial component of all ecosystems, as microbes have the potential to control any major biochemical process. In recent years, considerable strides have been made in describing the community structure,i.e. diversity and abundance, of microbes from the Earth’s major biomes. In virtually all environments studied, a few highly abundant taxa dominate the structure of microbial communities. Still, microbial diversity is high and is concentrated in the less abundant, or rare, fractions of the community,i.e. the “long tail” of the abundance distribution. The relationship between microbial community structure and activity, specifically the role of rare microbes, and its connection to ecosystem function, is not fully understood. We analyzed 12.3 million metagenomic and metatranscriptomic sequence assemblies and their genes from environmental, human, and engineered microbiomes, and show that microbial activity is dominated by rare microbes (96% of total activity) across all measured biomes. Further, rare microbial activity was comprised of traits that are fundamental to ecosystem and organismal health,e.g. biogeochemical cycling and infectious disease. The activity of rare microbes was also tightly coupled to temperature, revealing a link between basic biological processes,e.g. reaction rates, and community activity. Our study provides a broadly applicable and predictable paradigm that implicates rare microbes as the main microbial drivers of ecosystem function and organismal health.

scholarly journals Flotsam and jetsam: a global review of the role of inputs of marine organic matter in sandy beach ecosystems

2021 ◽  
Author(s):  
Glenn A. Hyndes ◽  
Emma Berdan ◽  
Cristian Duarte ◽  
Jenifer E. Dugan ◽  
Kyle A. Emery ◽  
...  
Keyword(s):  
Organic Matter ◽  
Food Webs ◽  
Food Source ◽  
Sandy Beach ◽  
Morphological Characteristics ◽  
Sandy Beaches ◽  
Marine Animals ◽  
Marine Organic Matter ◽  
Beach Cast

Sandy beaches are iconic interfaces that functionally link the ocean with the land by the flow of marine organic matter. These cross-ecosystem fluxes often comprise uprooted seagrass and dislodged macroalgae that can form substantial accumulations of detritus, termed ‘wrack’, on sandy beaches. In addition, the tissue of the carcasses of marine animals that regularly wash up on beaches form a rich food source (‘carrion’) for a diversity of scavenging animals. Here, we provide a global review of how wrack and carrion provide spatial subsidies that shape the structure and functioning of sandy beach ecosystems (sandy beaches and adjacent surf zones), which typically have little in situ primary production. We also examime the spatial scaling of the influence of these processes across the broader seascape and landscape, and identify key gaps in our knowledge to guide future research directions and priorities. Globally, large quantities of detrital kelp and seagrass can flow into sandy beach ecosystems, where microbial decomposers and animals remineralise and consume the imported organic matter. The supply and retention of wrack are influenced by the oceanographic processes that transport it, the geomorphology and landscape context of the recipient beaches, and the condition, life history and morphological characteristics of the taxa that are the ultimate source of wrack. When retained in beach ecosystems, wrack often creates hotspots of microbial metabolism, secondary productivity, biodiversity, and nutrient remineralization. Nutrients are produced during wrack break-down, and these can return to coastal waters in surface flows (swash) and the aquifier discharging into the subtidal surf. Beach-cast kelp often plays a key trophic role, being an abundant and preferred food source for mobile, semi-aquatic invertebrates that channel imported algal matter to predatory invertebrates, fish, and birds. The role of beach-cast marine carrion is likely to be underestimated, as it can be consumed rapidly by highly mobile scavengers (e.g. foxes, coyotes, raptors, vultures). These consumers become important vectors in transferring marine productivity inland, thereby linking marine and terrestrial ecosystems. Whilst deposits of organic matter on sandy beach ecosystems underpin a range of ecosystem functions and services, these can be at variance with aesthetic perceptions resulting in widespread activities, such ‘beach cleaning and grooming’. This practice diminishes the energetic base of food webs, intertidal fauna, and biodiversity. Global declines in seagrass beds and kelp forests (linked to global warming) are predicted to cause substantial reductions in the amounts of marine organic matter reaching many beach ecosystems, likely causing flow-on effects on food webs and biodiversity. Similarly, future sea-level rise and stormier seas are likely to profoundly alter the physical attributes of beaches, which in turn can change the rates at which beaches retain and process the influxes of wrack and animal carcasses. Conservation of the multi-faceted ecosystem services that sandy beaches provide will increasingly need to encompass a greater societal appreciation and the safeguarding of ecological functions reliant on beach-cast organic matter on innumerable ocean shores worldwide.

The Role of Nitrate Reduction in Plant Flooding Survival

2004 ◽  
pp. 357-371
Author(s):  
M. Stoimenova ◽  
W. M. Kaiser
Keyword(s):  
Nitrate Reduction
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