scholarly journals Metabolic responses of photosynthetic sea slugs to a changing environment

2016 ◽  
Author(s):  
Jacey C Van Wert
Keyword(s):  
Photosynthetic Efficiency ◽  
Environmental Changes ◽  
Metabolic Response ◽  
Short Term ◽  
Respiration Rates ◽  
Complex Interactions ◽  
Sea Slugs ◽  
Metabolic Suppression ◽  
The Difference ◽  
Algal Distribution

Sacoglossan sea slugs have complex interactions with their environment. They are well known for their ability to sequester stolen chloroplasts and utilize them for photoautotrophic CO2 fixation, yet the dependence on this is not clear in most species. Elysia stylifera is an Indo-Pacific tropical sacoglossan that selectively consumes Halimeda macroalgae and retains its chloroplasts for two weeks. This association is prone to change as their habitats are subjected to increased ocean warmth and acidification, altering algal distribution and decreasing photosynthetic efficiency. This study aimed to investigate the metabolic response of E. stylifera to projected environmental changes. Elysia stylifera were subjected to ambient (28°C) or warm (30°C) conditions and five days of food deprivation. On the first and fifth day of starvation, the respiration rates of individuals were measured in the dark to quantify slug response, as well as in the light to characterize their response when given the ability to photosynthesize. Dark treatments showed that slugs deprived of food undergo metabolic suppression in current conditions, but may not undergo suppression in projected warm conditions. The difference between oxygen consumption in dark and light treated slugs demonstrated photosynthesis occurred, but that it was reduced under all stressors. This study reveals that forecasted ocean warming may not be favorable for short-term photosynthetic sea slugs because of its impact on both the sea slugs and their ingested kleptoplasts. It also presents new uncertainties about the benefits of kleptoplasty and how it may transform with climate change.

scholarly journals Metabolic responses of photosynthetic sea slugs to a changing environment

2016 ◽  
Author(s):  
Jacey C Van Wert
Keyword(s):  
Photosynthetic Efficiency ◽  
Environmental Changes ◽  
Metabolic Response ◽  
Short Term ◽  
Respiration Rates ◽  
Complex Interactions ◽  
Sea Slugs ◽  
Metabolic Suppression ◽  
The Difference ◽  
Algal Distribution

Sacoglossan sea slugs have complex interactions with their environment. They are well known for their ability to sequester stolen chloroplasts and utilize them for photoautotrophic CO2 fixation, yet the dependence on this is not clear in most species. Elysia stylifera is an Indo-Pacific tropical sacoglossan that selectively consumes Halimeda macroalgae and retains its chloroplasts for two weeks. This association is prone to change as their habitats are subjected to increased ocean warmth and acidification, altering algal distribution and decreasing photosynthetic efficiency. This study aimed to investigate the metabolic response of E. stylifera to projected environmental changes. Elysia stylifera were subjected to ambient (28°C) or warm (30°C) conditions and five days of food deprivation. On the first and fifth day of starvation, the respiration rates of individuals were measured in the dark to quantify slug response, as well as in the light to characterize their response when given the ability to photosynthesize. Dark treatments showed that slugs deprived of food undergo metabolic suppression in current conditions, but may not undergo suppression in projected warm conditions. The difference between oxygen consumption in dark and light treated slugs demonstrated photosynthesis occurred, but that it was reduced under all stressors. This study reveals that forecasted ocean warming may not be favorable for short-term photosynthetic sea slugs because of its impact on both the sea slugs and their ingested kleptoplasts. It also presents new uncertainties about the benefits of kleptoplasty and how it may transform with climate change.

Validation of On-line Respiration Meter and its Applications by Computer Simulation

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1355-1363 ◽  
Author(s):  
C-W. Kim ◽  
H. Spanjers ◽  
A. Klapwijk
Keyword(s):  
Steady State ◽  
Activated Sludge ◽  
Respiration Rate ◽  
Oxygen Demand ◽  
Operating Conditions ◽  
Mass Balances ◽  
Short Term ◽  
Respiration Rates ◽  
On Line ◽  
Made In

An on-line respiration meter is presented to monitor three types of respiration rates of activated sludge and to calculate effluent and influent short term biochemical oxygen demand (BODst) in the continuous activated sludge process. This work is to verify if the calculated BODst is reliable and the assumptions made in the course of developing the proposed procedure were acceptable. A mathematical model and a dynamic simulation program are written for an activated sludge model plant along with the respiration meter based on mass balances of BODst and DO. The simulation results show that the three types of respiration rate reach steady state within 15 minutes under reasonable operating conditions. As long as the respiration rate reaches steady state the proposed procedure calculates the respiration rate that is equal to the simulated. Under constant and dynamic BODst loading, the proposed procedure is capable of calculating the effluent and influent BODst with reasonable accuracy.

scholarly journals Prevalence and Photobiology of Photosynthetic Dinoflagellate Endosymbionts in the Nudibranch Berghia stephanieae

Animals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2200
Author(s):  
Ruben X. G. Silva ◽  
Paulo Cartaxana ◽  
Ricardo Calado
Keyword(s):  
Food Deprivation ◽  
Photosynthetic Efficiency ◽  
Rapid Decrease ◽  
Complete Loss ◽  
Symbiotic Association ◽  
Non Invasive ◽  
Sea Slugs ◽  
Non Destructive ◽  
Over Time

Berghia stephanieae is a stenophagous sea slug that preys upon glass anemones, such as Exaiptasia diaphana. Glass anemones host photosynthetic dinoflagellate endosymbionts that sea slugs ingest when consuming E. diaphana. However, the prevalence of these photosynthetic dinoflagellate endosymbionts in sea slugs appears to be short-lived, particularly if B.stephanieae is deprived of prey that host these microalgae (e.g., during bleaching events impacting glass anemones). In the present study, we investigated this scenario, along with food deprivation, and validated the use of a non-invasive and non-destructive approach employing chlorophyll fluorescence as a proxy to monitor the persistence of the association between sea slugs and endosymbiotic photosynthetic dinoflagellates acquired through the consumption of glass anemones. Berghia stephanieae deprived of a trophic source hosting photosynthetic dinoflagellate endosymbionts (e.g., through food deprivation or by feeding on bleached E. diaphana) showed a rapid decrease in minimum fluorescence (Fo) and photosynthetic efficiency (Fv/Fm) when compared to sea slugs fed with symbiotic anemones. A complete loss of endosymbionts was observed within 8 days, confirming that no true symbiotic association was established. The present work opens a new window of opportunity to rapidly monitor in vivo and over time the prevalence of associations between sea slugs and photosynthetic dinoflagellate endosymbionts, particularly during bleaching events that prevent sea slugs from incorporating new microalgae through trophic interactions.

scholarly journals THE VALUE OF ROBUST STATISTICAL FORECASTS IN THE COVID-19 PANDEMIC

2021 ◽  
Vol 256 ◽  
pp. 19-43
Author(s):  
Jennifer L. Castle ◽  
Jurgen A. Doornik ◽  
David F. Hendry
Keyword(s):  
Structural Change ◽  
Measurement Errors ◽  
Epidemiological Models ◽  
Short Term ◽  
Data Measurement ◽  
Policy Interventions ◽  
Changing Trends ◽  
Technological Advances ◽  
The Difference ◽  
The Uk

The Covid-19 pandemic has put forecasting under the spotlight, pitting epidemiological models against extrapolative time-series devices. We have been producing real-time short-term forecasts of confirmed cases and deaths using robust statistical models since 20 March 2020. The forecasts are adaptive to abrupt structural change, a major feature of the pandemic data due to data measurement errors, definitional and testing changes, policy interventions, technological advances and rapidly changing trends. The pandemic has also led to abrupt structural change in macroeconomic outcomes. Using the same methods, we forecast aggregate UK unemployment over the pandemic. The forecasts rapidly adapt to the employment policies implemented when the UK entered the first lockdown. The difference between our statistical and theory based forecasts provides a measure of the effect of furlough policies on stabilising unemployment, establishing useful scenarios had furlough policies not been implemented.

scholarly journals How Do Subway Signs Affect Pedestrians’ Wayfinding Behavior through Visual Short-Term Memory?

2021 ◽  
Vol 13 (12) ◽  
pp. 6866
Author(s):  
Haoru Li ◽  
Jinliang Xu ◽  
Xiaodong Zhang ◽  
Fangchen Ma
Keyword(s):  
Public Transportation ◽  
Short Term Memory ◽  
Memory Capacity ◽  
Cognitive Test ◽  
Subway Station ◽  
Short Term ◽  
Term Memory ◽  
Visual Short Term Memory ◽  
The Difference ◽  
Types Of Information

Recently, subways have become an important part of public transportation and have developed rapidly in China. In the subway station setting, pedestrians mainly rely on visual short-term memory to obtain information on how to travel. This research aimed to explore the short-term memory capacities and the difference in short-term memory for different information for Chinese passengers regarding subway signs. Previous research has shown that people’s general short-term memory capacity is approximately four objects and that, the more complex the information, the lower people’s memory capacity. However, research on the short-term memory characteristics of pedestrians for subway signs is scarce. Hence, based on the STM theory and using 32 subway signs as stimuli, we recruited 120 subjects to conduct a cognitive test. The results showed that passengers had a different memory accuracy for different types of information in the signs. They were more accurate regarding line number and arrow, followed by location/text information, logos, and orientation. Meanwhile, information type, quantity, and complexity had significant effects on pedestrians’ short-term memory capacity. Finally, according to our results that outline the characteristics of short-term memory for subway signs, we put forward some suggestions for subway signs. The findings will be effective in helping designers and managers improve the quality of subway station services as well as promoting the development of pedestrian traffic in such a setting.

scholarly journals Forecasting Agroforestry Ecosystem Services Provision in Urban Regeneration Projects: Experiences and Perspectives from Milan

2021 ◽  
Vol 13 (5) ◽  
pp. 2434 ◽  
Author(s):  
Ambrogio Zanzi ◽  
Federico Andreotti ◽  
Valentina Vaglia ◽  
Sumer Alali ◽  
Francesca Orlando ◽  
...  
Keyword(s):  
Ecosystem Services ◽  
Food System ◽  
Environmental Changes ◽  
Urban Environments ◽  
Urban Food System ◽  
Notable Increase ◽  
Living Fences ◽  
The Difference ◽  
Pollution Removal ◽  
The Relationship

The expansion of urban agglomerates is causing significant environmental changes, while the demand and need for sustainability keep on growing. In this context, urban and peri-urban agriculture can play a crucial role, mainly if associated with an agroecological approach. Indeed, the extensive use of living fences and tree rows can improve the environmental quality, assuring ecosystem services (ES), developing a sustainable urban food system and increasing local productions and the related socio-economic improvements. This study aims to assess the benefits of an agroecological requalification of a dismissed peri-urban area in the South Milan Agricultural Regional Park (Italy), by evaluating two possible scenarios, both involving planting trees and shrubs in that area. The software I-Tree Eco simulates the ecosystem services provision of planting new hedgerows, evaluating the benefits over 30 years. The study underlines the difference between the two scenarios and how the planted area becomes an essential supplier of regulating ecosystem services for the neighbourhoods, increasing carbon storage and air pollution removal. Results were then analysed with a treemap, to better investigate and understand the relationship between the different ecosystem services, showing a notable increase in carbon sequestration at the end of the simulation (at year 30). The study shows a replicable example of a methodology and techniques that can be used to assess the ES in urban and peri-urban environments.

Ecological succession as an aspect of structure in fossil communities

Paleobiology ◽  
1975 ◽  
Vol 1 (3) ◽  
pp. 238-257 ◽  
Author(s):  
Kenneth R. Walker ◽  
Leonard P. Alberstadt
Keyword(s):  
Environmental Changes ◽  
Food Chains ◽  
Short Term ◽  
Niche Specialization ◽  
Pattern Diversity ◽  
Physical Environments ◽  
Autogenic Succession ◽  
Succession Stage ◽  
Stratigraphic Sequences

Succession involves changes in a community through time, whether internally or externally controlled. As succession progresses, niche specialization, species diversity (variety and equitability), complexity of food chains, and pattern diversity increase; net production and species growth rate decrease. We apply the succession concept to three types of ancient community sequences: 1) fossil reefs (Ordovician—Cretaceous in age), 2) short-term successions occurring through thin stratigraphic intervals, and 3) long-term successions occurring through thicker stratigraphic intervals. Ancient reefs show four vertical zones: (1) a basal stabilization zone (autogenic), 2) the overlying colonization zone (autogenic, pioneer stage), 3) the diversification zone, the bulk of most reefs (diversification culminating in climax), and 4) the uppermost domination zone. The first three zones represent autogenic succession but the final stage may involve allogenic succession. Short-term succession usually occurs where periodic allogenic catastrophes wipe out the community which is rebuilt through autogenic succession. Opportunistic pioneer species are important and in our examples (Ordovician, Silurian, and Cretaceous) are species which pave soft substrata. Paleozoic strophomenid brachiopods filled this role, and inoceramid pelecypods served the function in the Mesozoic. The succession which begins with opportunists progresses to a climax community of equilibrists. Repetition of catastrophe-succession couplets produces a cyclic stratigraphic record. Long-term successions are recorded in thicker stratigraphic sequences, and are of two types: 1) autogenic succession in unchanging physical environments and 2) allogenic succession in changing physical environments. Our examples of these are from the Devonian Haragan-Bois D'Arc formations of Oklahoma and the Lime Creek Formation of Iowa. This type of succession represents a temporal-spatial mosaic. The Haragan data (unchanging environments) indicate characteristic, intergrading, and ubiquitous species in the brachiopod communities. Most ubiquitous species in the pioneer community were eurytopic opportunists. The Lime Creek data allows testing of the prediction that environmental changes cause regression to an earlier succession stage. The brachiopod communities after environmental changes have more ubiquitous and intergrading eurytopic species. These represent an earlier stage in the succession.

Effect of short-term propionate infusion on feed intake and blood parameters in sheep

1997 ◽  
Vol 272 (6) ◽  
pp. E997-E1001 ◽  
Author(s):  
H. G. Leuvenink ◽  
E. J. Bleumer ◽  
L. J. Bongers ◽  
J. van Bruchem ◽  
D. van der Heide
Keyword(s):  
Portal Vein ◽  
Feed Intake ◽  
Blood Parameters ◽  
Feeding Pattern ◽  
Short Term ◽  
Mesenteric Vein ◽  
The Difference ◽  
High Doses

The hypothesis that propionate is a short-term feed intake-regulating agent was studied. Mature wether sheep were infused over 20 min with Na propionate into the mesenteric vein, while feed intake and feeding pattern were monitored over 1.5 h. Feed intake was reduced by infusions at 2 mmol/min, which were associated with marked increases in jugular as well as portal concentrations of insulin, glucose, and propionate. In a second experiment, animals were infused with 2 mmol/min Na propionate into the portal vein. No decrease in feed intake was observed, although there were similar increases in insulin, glucose, and propionate as found in mesenteric vein-infused animals. It is concluded that mesenteric propionate in high doses acts as a satiety factor. Possible explanations for the difference between site of infusion may be a different distribution of the infusate over the liver and/or the presence of propionate-sensitive receptors in the mesenteric/portal vein region. It seems unlikely that insulin concentrations are involved in inducing satiety in propionate-infused animals.

scholarly journals Adaptation-induced modification of motion selectivity tuning in visual tectal neurons of adult zebrafish

2015 ◽  
Vol 114 (5) ◽  
pp. 2893-2902 ◽  
Author(s):  
Vanessa Hollmann ◽  
Valerie Lucks ◽  
Rafael Kurtz ◽  
Jacob Engelmann
Keyword(s):  
Optic Tectum ◽  
Brain Area ◽  
Direction Selectivity ◽  
Adult Brain ◽  
Orientation Tuning ◽  
Adult Zebrafish ◽  
Short Term ◽  
Short Term Plasticity ◽  
The Difference ◽  
Tectal Neurons

In the developing brain, training-induced emergence of direction selectivity and plasticity of orientation tuning appear to be widespread phenomena. These are found in the visual pathway across different classes of vertebrates. Moreover, short-term plasticity of orientation tuning in the adult brain has been demonstrated in several species of mammals. However, it is unclear whether neuronal orientation and direction selectivity in nonmammalian species remains modifiable through short-term plasticity in the fully developed brain. To address this question, we analyzed motion tuning of neurons in the optic tectum of adult zebrafish by calcium imaging. In total, orientation and direction selectivity was enhanced by adaptation, responses of previously orientation-selective neurons were sharpened, and even adaptation-induced emergence of selectivity in previously nonselective neurons was observed in some cases. The different observed effects are mainly based on the relative distance between the previously preferred and the adaptation direction. In those neurons in which a shift of the preferred orientation or direction was induced by adaptation, repulsive shifts (i.e., away from the adapter) were more prevalent than attractive shifts. A further novel finding for visually induced adaptation that emerged from our study was that repulsive and attractive shifts can occur within one brain area, even with uniform stimuli. The type of shift being induced also depends on the difference between the adapting and the initially preferred stimulus direction. Our data indicate that, even within the fully developed optic tectum, short-term plasticity might have an important role in adjusting neuronal tuning functions to current stimulus conditions.

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