scholarly journals Exposure to low concentrations of pesticide stimulates ecological functioning in the dung beetle Onthophagus nuchicornis

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10359
Author(s):  
Paul Manning ◽  
G. Christopher Cutler
Keyword(s):  
Body Size ◽  
Environmental Stress ◽  
Ecosystem Functioning ◽  
Dung Beetle ◽  
Ecosystem Functions ◽  
Environmental Stressor ◽  
Low Concentrations ◽  
Important Trait ◽  
High Doses ◽  
Ecological Functioning

Body-size is an important trait for predicting how species contribute to ecosystem functions and respond to environmental stress. Using the dung beetle Onthophagus nuchicornis (Coleoptera: Scarabaeidae), we explored how variation in body-size affected ecosystem functioning (dung burial) and sensitivity to an environmental stressor (exposure to the veterinary anthelmintic ivermectin). We found that large beetles buried nearly 1.5-fold more dung than small beetles, but that mortality from exposure to a range of concentrations of ivermectin did not differ between large and small beetles. Unexpectedly, we found that exposure to low concentrations of ivermectin (0.01⁠–1 mg ivermectin per kg dung) stimulated dung burial in both small and large beetles. Our results provide evidence of ecological functioning hormesis stemming from exposure to low amounts of a chemical stressor that causes mortality at high doses.

scholarly journals Disentangling the effect of body size and phylogenetic distances on zooplankton top-down control of algae

2016 ◽  
Vol 283 (1828) ◽  
pp. 20160487 ◽  
Author(s):  
Andros T. Gianuca ◽  
Jelena H. Pantel ◽  
Luc De Meester
Keyword(s):  
Body Size ◽  
Ecosystem Functioning ◽  
Phylogenetic Signal ◽  
Niche Partitioning ◽  
Biodiversity Loss ◽  
Taxonomic Diversity ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Top Down ◽  
Niche Differences

A negative consequence of biodiversity loss is reduced rates of ecosystem functions. Phylogenetic-based biodiversity indices have been claimed to provide more accurate predictions of ecosystem functioning than species diversity alone. This approach assumes that the most relevant traits for ecosystem functioning present a phylogenetic signal. Yet, traits-mediating niche partitioning and resource uptake efficiency in animals can be labile. To assess the relative power of a key trait (body size) and phylogeny to predict zooplankton top-down control on phytoplankton, we manipulated trait and phylogenetic distances independently in microcosms while holding species richness constant. We found that body size provided strong predictions of top-down control. In contrast, phylogeny was a poor predictor of grazing rates. Size-related grazing efficiency asymmetry was mechanistically more important than niche differences in mediating ecosystem function in our experimental settings. Our study demonstrates a strong link between a single functional trait (i.e. body size) in zooplankton and trophic interactions, and urges for a cautionary use of phylogenetic information and taxonomic diversity as substitutes for trait information to predict and understand ecosystem functions.

Effects of Vancomycin on Platelets, Plasma Proteins and Hepatitis B Surface Antigen

1975 ◽  
Vol 34 (01) ◽  
pp. 083-093 ◽  
Author(s):  
Barry S Coller ◽  
W. B Lundberg ◽  
Harvey R Gralnick
Keyword(s):  
Hepatitis B ◽  
Factor Viii ◽  
Surface Antigen ◽  
Plasma Proteins ◽  
Hepatitis B Surface Antigen ◽  
Infusion Site ◽  
Vancomycin Therapy ◽  
Intravenous Injections ◽  
Low Concentrations ◽  
High Doses

SummaryThe antibiotic vancomycin shares many similarities with ristocetin, an agent noted for its effects on platelets and plasma fibrinogen. Vancomycin did not aggregate platelets as ristocetin, but platelets were incorporated into precipitates induced by vancomycin. Fibrinogen and factor VIII were precipitated from plasma at low concentrations of vancomycin. The precipitated fibrinogen remained clottable. Hepatitis B surface antigen was selectively precipitated from serum and could be recovered from the precipitate. Rabbits receiving bolus intravenous injections of high doses of vancomycin developed hypofibrinogenemia and thrombocytopenia within minutes and often went on to die. Studies with 125I-vancomycin revealed little stable binding of the antibiotic to platelets or fibrinogen. A relationship is suggested between the potent protein precipitating effects and phlebitis at the infusion site commonly associated with vancomycin therapy.

Size does not matter for male Marbled Salamanders (Ambystoma opacum)

2015 ◽  
Vol 93 (10) ◽  
pp. 735-740
Author(s):  
D.A. Croshaw ◽  
J.H.K. Pechmann
Keyword(s):  
Sexual Selection ◽  
Body Size ◽  
Reproductive Success ◽  
Large Male ◽  
Male Mating ◽  
Ambystoma Opacum ◽  
Positive Assortative Mating ◽  
Important Trait ◽  
Breeding Groups ◽  
Gravid Females

Understanding the phenotypic attributes that contribute to variance in mating and reproductive success is crucial in the study of evolution by sexual selection. In many animals, body size is an important trait because larger individuals enjoy greater fitness due to the ability to secure more mates and produce more offspring. Among males, this outcome is largely mediated by greater success in competition with rival males and (or) advantages in attractiveness to females. Here we tested the hypothesis that large male Marbled Salamanders (Ambystoma opacum (Gravenhorst, 1807)) mate with more females and produce more offspring than small males. In experimental breeding groups, we included males chosen specifically to represent a range of sizes. After gravid females mated and nested freely, we collected egg clutches and genotyped all adults and samples of hatchlings with highly variable microsatellite markers to assign paternity. Size had little effect on male mating and reproductive success. Breeding males were not bigger than nonbreeding males, mates of polyandrous females were not smaller than those of monogamous females, and there was no evidence for positive assortative mating by size. Although body size did not matter for male Marbled Salamanders, we documented considerable fitness variation and discuss alternative traits that could be undergoing sexual selection.

scholarly journals The Roles of Dietary Glutamate in the Intestine

2018 ◽  
Vol 73 (Suppl. 5) ◽  
pp. 15-20 ◽  
Author(s):  
Daniel Tomé
Keyword(s):  
Monosodium Glutamate ◽  
Amino Acid Content ◽  
Intestinal Lumen ◽  
Free Form ◽  
Blood Levels ◽  
Umami Taste ◽  
Low Concentrations ◽  
Cephalic Phase ◽  
Gut Function ◽  
High Doses

Glutamate (Glu), either as one of the amino acids of protein or in free form, constitutes up to 8–10% of amino acid content in the human diet, with an intake of about 10–20 g/day in adults. In the intestine, postprandial luminal Glu concentrations can be of the order of mM and result in a high intra-mucosal Glu concentration. Glu absorbed from the intestinal lumen is for a large part metabolized by enterocytes in various pathways, including the production of energy to support intestinal motility and functions. Glu is the most important fuel for intestinal tissue, it is involved in gut protein metabolism and is the precursor of different important molecules produced within the intestinal mucosa (2-oxoglutarate, L-alanine, ornithine, arginine, proline, glutathione, γ-aminobutyric acid [GABA]). Studies in adult humans, pigs, piglets or preterm infants indicate that a large proportion of Glu is metabolized in the intestine, and that for the usual range of Glu dietary intake (bound Glu and free Glu including added Glu as a food additive in normal amounts up to 1 g/day), circulating Glu is tightly maintained at rather low concentrations. Systemic blood levels of Glu transiently rise when high doses monosodium glutamate (> 10–12 g), higher than normal human dietary consumption, are ingested and normalize within 2 h after the offset of consumption. Glu is also involved in oral and post oral nutrient chemosensing that involves gustatory nerves and both humoral and neural (vagal) gut-brain pathways with an impact on gut function and feeding behavior. Glu functions as a signaling molecule in the enteric nervous system and modulates neuroendocrine reflexes in the gastrointestinal tract. The oral taste sensation of Glu involves its binding to the oral umami taste receptors that triggers the cephalic phase response of digestion to prepare for food digestion. Glu is sensed again in the gut, inducing a visceral sensation that enhances additional gut digestive processes through the visceral sense (vago-vagal reflex).

scholarly journals Plant traits are poor predictors of long-term ecosystem functioning

2019 ◽  
Author(s):  
Fons van der Plas ◽  
Thomas Schröder-Georgi ◽  
Alexandra Weigelt ◽  
Kathryn Barry ◽  
Sebastian Meyer ◽  
...  
Keyword(s):  
Plant Species ◽  
Ecosystem Functioning ◽  
Plant Traits ◽  
Vascular Plant ◽  
Plant Performance ◽  
Ecosystem Functions ◽  
Average Percentage ◽  
Functional Consequences ◽  
Small Set

ABSTRACTEarth is home to over 350,000 vascular plant species1 that differ in their traits in innumerable ways. Yet, a handful of functional traits can help explaining major differences among species in photosynthetic rate, growth rate, reproductive output and other aspects of plant performance2–6. A key challenge, coined “the Holy Grail” in ecology, is to upscale this understanding in order to predict how natural or anthropogenically driven changes in the identity and diversity of co-occurring plant species drive the functioning of ecosystems7, 8. Here, we analyze the extent to which 42 different ecosystem functions can be predicted by 41 plant traits in 78 experimentally manipulated grassland plots over 10 years. Despite the unprecedented number of traits analyzed, the average percentage of variation in ecosystem functioning that they jointly explained was only moderate (32.6%) within individual years, and even much lower (12.7%) across years. Most other studies linking ecosystem functioning to plant traits analyzed no more than six traits, and when including either only six random or the six most frequently studied traits in our analysis, the average percentage of explained variation in across-year ecosystem functioning dropped to 4.8%. Furthermore, different ecosystem functions were driven by different traits, with on average only 12.2% overlap in significant predictors. Thus, we did not find evidence for the existence of a small set of key traits able to explain variation in multiple ecosystem functions across years. Our results therefore suggest that there are strong limits in the extent to which we can predict the long-term functional consequences of the ongoing, rapid changes in the composition and diversity of plant communities that humanity is currently facing.

scholarly journals Impairment of microbial and meiofaunal ecosystem functions linked to algal forest loss

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Silvia Bianchelli ◽  
Roberto Danovaro
Keyword(s):  
Habitat Loss ◽  
Ecosystem Functioning ◽  
Negative Impact ◽  
Ecosystem Functions ◽  
Marine Biodiversity ◽  
Forest Loss ◽  
Higher Taxa ◽  
Vulnerable Habitats ◽  
Nematode Biodiversity ◽  
Barren Grounds

AbstractHabitat loss is jeopardizing marine biodiversity. In the Mediterranean Sea, the algal forests of Cystoseira spp. form one of the most complex, productive and vulnerable shallow-water habitats. These forests are rapidly regressing with negative impact on the associated biodiversity, and potential consequences in terms of ecosystem functioning. Here, by comparing healthy Cystoseira forests and barren grounds (i.e., habitats where the macroalgal forests disappeared), we assessed the effects of habitat loss on meiofaunal and nematode biodiversity, and on some ecosystem functions (here measured in terms of prokaryotic and meiofaunal biomass). Overall, our results suggest that the loss of Cystoseira forests and the consequent barren formation is associated with the loss of meiofaunal higher taxa and a decrease of nematode biodiversity, leading to the collapse of the microbial and meiofaunal variables of ecosystem functions. We conclude that, given the very limited resilience of these ecosystems, active restoration of these vulnerable habitats is needed, in order to recover their biodiversity, ecosystem functions and associated services.

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