Search results for "Browning"
showing 10 items of 61 documents
Influence of littoral periphyton on whole-lake metabolism relates to littoral vegetation in humic lakes
2017
The role of littoral habitats in lake metabolism has been underrated, especially in humic lakes, based on an assumption of low benthic primary production (PP) due to low light penetration into water. This assumption has been challenged by recent recognition of littoral epiphyton dominance of whole-lake PP in a small highly humic lake and of epiphyton as an important basal food source for humic lake biota. However, as these studies have mostly concerned single lakes, there is a need to test their wider generality. We studied the whole-lake PP and community respiration (CR) in eight small humic lakes in southern Finland during July 2015 using 14 C incorporation to measure pelagic PP and the c…
Ecosystem responses to increased organic carbon concentration: comparing results based on long-term monitoring and whole-lake experimentation
2019
Recent increases in terrestrial dissolved organic carbon (DOC) concentrations in northern inland waters have many ecological consequences. We examined available data on carbon cycles and food webs of 2 boreal headwater lakes in southern Finland. Basic limnology and catchment characteristics of a pristine lake, Valkea-Kotinen (VK), were monitored over the past 25 years while the lake has undergone browning and DOC increased from similar to 11 to 13 mg L-1. Pronounced changes in the early 2000s represent a regime shift in DOC concentration and color. Lake Alinen Mustajarvi (AM) was manipulated for 2 years by additions of labile DOC (cane sugar), raising the DOC concentration from similar to 1…
Reevaluating the Role of Organic Matter Sources for Coastal Eutrophication, Oligotrophication, and Ecosystem Health
2019
Organic matter (OM) in aquatic systems is either produced internally (autochthonous OM) or delivered from the terrestrial environment (ter-OM). For eutrophication (or the reverse – oligotrophication), the amount of autochthonous OM plays a key role for coastal ecosystem health. However, the influence of ter-OM on eutrophication or oligotrophication processes of coastal ecosystems is largely unclear. Therefore, ter-OM, or ter-OM proxies are currently not included in most policies or monitoring programs on eutrophication. Nevertheless, ter-OM is increasingly recognized as a strong driver of aquatic productivity: By influencing underwater light conditions and nutrient- and carbon availability,…
UV-screening and springtime recovery of photosynthetic capacity in leaves of Vaccinium vitis-idaea above and below the snow pack
2019
International audience; Evergreen plants in boreal biomes undergo seasonal hardening and dehardening adjusting their photosynthetic capacity and photoprotection; acclimating to seasonal changes in temperature and irradiance. Leaf epidermal ultraviolet (UV)-screening by flavonols responds to solar radiation, perceived in part through increased ultraviolet-B (UV-B) radiation, and is a candidate trait to provide cross-photoprotection. At Hyytiälä Forestry Station, central Finland, we examined whether the accumulation of flavonols was higher in leaves of Vaccinium vitis-idaea L. growing above the snowpack compared with those below the snowpack. We found that leaves exposed to colder temperature…
Inhibitory Effect of Azamacrocyclic Ligands on Polyphenol Oxidase in Model and Food Systems
2020
[EN] Enzymatic browning is one of the main problems faced by the food industry due to the enzyme polyphenol oxidase (PPO) provoking an undesirable color change in the presence of oxygen. Here, we report the evaluation of 10 different azamacrocyclic compounds with diverse morphologies as potential inhibitors against the activity of PPO, both in model and real systems. An initial screening of 10 ligands shows that all azamacrocyclic compounds inhibit to some extent the enzymatic browning, but the molecular structure plays a crucial role on the power of inhibition. Kinetic studies of the most active ligand (L2) reveal a S-parabolic I-parabolic noncompetitive inhibition mechanism and a remarkab…
How to Deal with Uninvited Guests in Wine: Copper and Copper-containing Oxidases
2020
Copper is one of the most frequently occurring heavy metals in must and wine. It is introduced by pesticides, brass fittings, and as copper sulphate for treatment of reductive off-flavors. At higher concentrations, copper has harmful effects on the wine. It contributes to the oxidation of wine ingredients, browning reactions, cloudiness, inhibition of microorganisms, and wine fermentation. Last but not least, there is also a danger to the consumer. At present, some physicochemical methods exist to reduce the copper content in must and wine, but they all have their shortcomings. A possible solution is the biosorption of metals by yeasts or lactobacilli. Copper can also reach must and wine in…
Effects of Modified Atmosphere Packaging and Chitosan Treatment on Quality and Sensorial Parameters of Minimally Processed cv. ‘Italia’ Table Grapes
2021
Table grape is a non-climacteric fruit, very sensitive to water loss and gray mold during postharvest handling and storage. The aim of this work was to evaluate the effects of modified atmosphere packaging and chitosan treatment on quality and sensorial parameters of minimally processed cv. ‘Italia’ table grape during cold storage (14 days at 5 °C) and shelf-life (7 and 14 days of cold storage plus 5 days at 20 °C), reproducing a retail sales condition. Our data showed a significant effect of high CO2-modified atmosphere in combination with chitosan and alone on preserving quality, sensorial parameters, and delaying decay of minimally processed table grape. The most effective treatment in t…
Eutrophication and browning influence Daphnia nutritional ecology
2019
Climate change and land-use practices can enhance lake eutrophication and browning, which influence phytoplankton composition by decreasing the availability of food high in nutritional quality (algae) and increasing the abundance of low-quality food (terrestrial detritus, bacteria) for herbivorous zooplankton. Nutritionally valuable algae for zooplankton are rich in essential biomolecules such as amino acids, polyunsaturated fatty acids (PUFAs), sterols, and phosphorus. We performed laboratory experiments and showed a stronger positive relationship between zooplankton (Daphnia) cumulative offspring number and availability of high-quality algae (Cryptophytes: Rhodomonas/Cryptomonas; and Chry…
Lyophilized Maqui (Aristotelia chilensis) Berry Induces Browning in the Subcutaneous White Adipose Tissue and Ameliorates the Insulin Resistance in H…
2019
Maqui (Aristotelia Chilensis) berry features a unique profile of anthocyanidins that includes high amounts of delphinidin-3-O-sambubioside-5-O-glucoside and delphinidin-3-O-sambubioside and has shown positive effects on fasting glucose and insulin levels in humans and murine models of type 2 diabetes and obesity. The molecular mechanisms underlying the impact of maqui on the onset and development of the obese phenotype and insulin resistance was investigated in high fat diet-induced obese mice supplemented with a lyophilized maqui berry. Maqui-dietary supplemented animals showed better insulin response and decreased weight gain but also a differential expression of genes involved in de novo…
Does iris(in) bring bad news or good news?
2017
Irisin, a novel myokine produced in response to physical activity, promotes white-to-brown fat transdifferentiation. The name irisin referred to the ancient Greek goddess Iris, the messenger who delivered (bad) news from the gods. In mice, it has been demonstrated that irisin plays a key role in metabolic regulation, energy expenditure and glucose homeostasis. New findings from various studies carried out in both animals and humans suggest that irisin might also have other favorable effects, such as increasing bone cortical mass, preventing hepatic lipid accumulation, and improving cognitive functions, thus mediating many exercise-induced health benefits. However, data on the role and funct…