Relative Consumption Rate Research Articles

Aquatic omnivores shift their trophic position towards increased plant consumption as plant stoichiometry becomes more similar to their body stoichiometry.

Human induced eutrophication has strongly altered aquatic ecosystems. With increasing eutrophication, plant nutrient concentrations increase, making them more attractive as food for herbivores. However, most aquatic consumers are omnivorous. Ecological stoichiometry theory predicts that animals prefer to consume food which has a similar nutrient (N and P) composition or C:nutrient ratio compared to their own bodies, hence omnivorous animals may prefer to eat animal prey instead of plants. We asked whether aquatic omnivores would shift their diet towards more plant consumption when plants are more nutritious and their stoichiometry becomes more similar to the stoichiometry of the omnivore. We hypothesized that: (1) the omnivore increases plant consumption as the plant C:nutrient ratio decreases when there is only plant material available; (2) the omnivore generally prefers animal food over plant material; (3) the omnivore will increase its relative plant consumption as the plant C:nutrient ratio decreases, in the presence of animal food. As a model system, we used the pond snail Lymnaea stagnalis (omnivorous consumer), the aquatic plant Potamogeton lucens (plant food to the consumer, cultured at different nutrient regimes to obtain different plant C:nutrient ratios), and the crustacean Gammarus pulex (animal food to the consumer, using freshly dead individuals). When there was only plant material available, the consumers increased their relative consumption rate with decreasing plant C:nutrient ratio from no measurable amount to about 102 mg g-1 day-1. When plant material was offered simultaneously with animal food, even though the omnivores always preferred animal food over plant material, the omnivores still increased their relative intake of plant material as plant C:nutrient ratio decreased, from virtually nothing at the highest to on average 16% of their diet at the lowest plant C:nutrient ratio, with a maximum of 28%. Therefore, we conclude that as nutrient loading increases in aquatic ecosystems, plant-eating omnivorous animals may shift their trophic position towards increased plant consumption and alter the food web structure. As a result, we may observe increased top-down control on aquatic plants.

Macro-detritivore identity and biomass along with moisture availability control forest leaf litter breakdown in a field experiment

Forests are structurally rich ecosystems with strong spatial variation in microclimate. Local temperature and soil moisture are important drivers of leaf litter breakdown, a key ecosystem process vital for forest functioning. Additionally, detritivore species composition and activity are equally dependent on microclimate, rendering changes in microclimate key to understand leaf litter breakdown. We investigated the interaction between microclimatic variables (i.e. temperature and moisture) and different combinations of macro-detritivores (a drought sensitive i.e. Oniscus asellus vs. a drought tolerant species i.e. Glomeris marginata) on litter breakdown of easily decomposable (high quality) Acer litter and decomposition resistant (low quality) Quercus litter in a full factorial microcosm field experiment in a temperate forest in Belgium. We hypothesize litter breakdown to be faster for high quality litter and macro-detritivore biomass and dependent on macro-detritivore identity, mediated by forest microclimate e.g. faster with higher soil moisture and warmer temperatures.We found high quality litter breakdown to be reduced by decreasing moisture availability, while it was not affected by temperature. There was no effect of moisture and temperature on litter breakdown of low quality litter. The effect of detritivore biomass on the breakdown of Quercus litter depended on detritivore identity: elevated millipede biomass increased Quercus litter breakdown, which was not the case for woodlice. There was a positive effect of macro-detritivore biomass but no effect of macro-detritivore identity on leaf litter breakdown of high quality litter. In addition, the relative consumption rates were equal between the drought sensitive (woodlouse) and the drought tolerant (millipede) species for high quality litter, but different for low quality litter. The woodlouse species was more efficient in the breakdown of low quality litter compared to our tested millipede species. Relative consumption rate was not influenced by the moisture or temperature treatments. Combining both detritivore taxa in a single microcosm had additive (non-synergistic) effects on litter breakdown, indicating that they are not complementary in their resource use. We conclude that mainly differences in moisture availability in forest ecosystems are important for litter breakdown and that detritivore identity is critical for the breakdown of especially low quality litter.

Induction of Resistance Against Plutella xylostella (L.) (Lep.: Plutellidae) by Jasmonic Acid and Mealy Cabbage Aphid Feeding in Brassica napus L.

The diamondback moth, Plutella xylostella (L.), has become the most destructive insect pest of cruciferous plants, such as B. napus throughout the world including Iran. In this study, the induction of resistance was activated in oilseed rape plants (Brassica napus L.) using foliar application of jasmonic acid (JA) and mealy cabbage aphid either individually or in combination against diamondback moth. Induced resistance by inducers significantly reduced the population growth parameters, as well as the survival rate of immature P. xylostella. Also, the nutritional indices of P. xylostella were studied to evaluate the potential impact of induced resistance on the insect feeding behavior. The values of the efficiency of conversion of ingested food, the efficiency of conversion of digested food, relative consumption rate, and relative growth rate of P. xylostella on JA-treated plants were significantly reduced compared to control. These are because glucosinolates and proteinase inhibitors are induced following treatment of plants. Also, we found a significantly higher glucose oxidase activity in the salivary gland extracts of larvae fed on JA treatment. These results express that JA and/or Aphid application induces systemic defenses in oilseed rape that have a negative effect on P. xylostella fitness. These findings develop our knowledge the effects of induced defenses on P. xylostella.

Influence of elevated CO2 on development and food utilization of armyworm Mythimna separata fed on transgenic Bt maize infected by nitrogen-fixing bacteria.

BackgroundBt crops will face a new ecological risk of reduced effectiveness against target-insect pests owing to the general decrease in exogenous-toxin content in Bt crops grown under elevated carbon dioxide (CO2). The method chosen to deal with this issue may affect the sustainability of transgenic crops as an effective pest management tool, especially under future atmospheric CO2 level raising.MethodsIn this study, rhizobacterias, as being one potential biological regulator to enhance nitrogen utilization efficiency of crops, was selected and the effects of Bt maize (Line IE09S034 with Cry1Ie vs. its parental line of non-Bt maize Xianyu 335) infected by Azospirillum brasilense (AB) and Azotobacter chroococcum (AC) on the development and food utilization of the target Mythimna separate under ambient and double-ambient CO2 in open-top chambers from 2016 to 2017.ResultsThe results indicated that rhizobacteria infection significantly increased the larval life-span, pupal duration, relative consumption rate and approximate digestibility of M. separata, and significantly decreased the pupation rate, pupal weight, adult longevity, fecundity, relative growth rate, efficiency of conversion of digested food and efficiency of conversion of ingested food of M. separata fed on Bt maize, while here were opposite trends in development and food utilization of M. separata fed on non-Bt maize infected with AB and AC compared with the control buffer in 2016 and 2017 regardless of CO2 level.DiscussionSimultaneously, elevated CO2 and Bt maize both had negative influence on the development and food utilization of M. separata. Presumably, CO2 concentration arising in future significantly can increase their intake of food and harm to maize crop; however, Bt maize infected with rhizobacterias can reduce the field hazards from M. separata and the application of rhizobacteria infection can enhance the resistance of Bt maize against target lepidoptera pests especially under elevated CO2.

Hypoglycemic activity in vitro of polysaccharides from Camellia oleifera Abel. seed cake

We isolated and purified polysaccharide from the Camellia oleifera Abel. seed cake (CCP) and studied its hypoglycemic activity in vitro. The molecular weight of CCP was 4736 Da and the monosaccharide molar composition ratio was: Xylose:Glucuronic acid:Galactosamine:Mannose = 10.9:4.4:2.6:1.8. The CCP contained conjugated proteins and belonged to acidic polysaccharide, which can promote the consumption of the glucose in the medium by HepG2 cells within the range of 0.125–0.500 mg/mL. Relative consumption rate (RCR) of the glucose was the highest at 0.5 mg/mL, exceeded that of the metformin hydrochloride, as well as that of Tea Polysaccharide under the same concentration. A meaningful structure activity relationship (SAR) of hypoglycemia polysaccharides had established. This result suggests that CCP can be used as hypoglycemic medicine or health food.

Stability of Metal Matrix Composite Pads During High-Speed Braking

Metal matrix composites are now commonly used as braking pads for the train running over 250 km/h by virtue of a number of desirable properties. To develop a fundamental understanding of the stability of metallic composites at high-speed braking, four typical composite materials, with different Cu and Fe contents, were subjected to a series of high-speed emergency braking at a simulative running speed of 380 km/h and a braking inertia of 27 kg/m−2 and a normal pressure of 1.27 MPa in this paper. The results showed that the sample with higher Cu content displayed a fade COF and deteriorated wear, but the one with higher Fe content could maintain a stable COF and low wear rate. The tribological behaviour is associated with the relative rate of generation and consumption of the tribo-oxide film. For the sample with higher Cu content, the generation rate of tribo-oxide film was less than the consumption rate, and the COF fading and wear deterioration with the increasing braking times were attributed to the reduction in resistance to deform or to shear the asperities, which was thought to be caused by the degradation of near-surface layer due to the removal of protective tribo-oxide film. In contrast, for the sample with higher Fe content, the generation rate was approximately equal to the consumption rate, and a well-established tribo-oxide film on the surface was responsible for the stable friction level and low wear rates.

Effects of Opuntia ficus-indica lectin on feeding, survival, and gut enzymes of maize weevil, Sitophilus zeamais

In this study, the effects of Opuntia ficus-indica lectin (OfiL) on the survival and nutritional parameters of Sitophilus zeamais (maize weevil) adults were evaluated. OfiL was incorporated into the artificial diets at concentrations of 15, 60, and 95 mg/g (mg of lectin per g of wheat flour). Mortality was evaluated after 7 and 15 days, and the amount of food ingested and the weight of the insects were determined on the 7th day. In addition, the in vitro effects of OfiL on the gut enzymes of the insect were investigated. The ingestion of OfiL did not show any significant difference in the mortality rates compared to control. The relative consumption rate was also similar to that of the control, and no deterrent effect was detected. However, the values of the relative biomass variation and the efficiency of ingested food conversion were negative in the treatments at 60 and 95 mg/g, showing that lectin ingestion resulted in weight loss. OfiL exhibited a stimulatory effect on the protease activity from S. zeamais gut extract, which may cause uncontrolled hydrolysis of proteins in the digestive tract. This lectin did not promote significant alteration in the amylase activity. In conclusion, OfiL was able to exert anti-nutritional effects without causing a deterrent effect.

Effects of Cd accumulation on cutworm Spodoptera litura larvae via Cd treated Chinese flowering cabbage Brassica campestris and artificial diets

By exposing herbivorous cutworm Spodoptera litura (Lepidoptera: Noctuidae) larvae to Cadmium (Cd) stress via Cd treated cabbages Brassica campestris and artificial diets, we investigated effects of Cd accumulation in larvae on their survival and food utilization. The results showed that Cd transferred from soils contaminated with different Cd concentrations through cabbages-larvae, and be mainly accumulated in larvae guts. There was a dose-response relationship between Cd accumulations in larvae cuticle, head, guts and Cd concentrations in artificial diets, and the highest one was found in the guts, regardless of generations. High Cd stress (10 mg kg−1 Cd in soil, 40.6, 81.2 mg kg−1 Cd in artificial diets) had inhibited effects on larvae growth and food utilization, whereas low Cd stress (Lvbao 701 planted in 2.5 mg kg−1 Cd soil, 4.06 mg kg−1 Cd in artificial diets) showed stimulated effect. Cd accumulations in the guts were significantly negative correlated with efficiency of conversion of ingested food (ECI) and relative growth rate (RGR) of larvae feeding on Cd treated diets or cabbages while were significantly positive correlated with relative consumption rate (RCR). Therefore, after S. litura larvae feed on Cd treated natural food or artificial diets, Cd could be transferred to different tissues, and mainly accumulated in the guts, which significantly affected growth and food utilization. Additionally, Cd stress via Cd treated artificial diets presented less detrimental effects on S. litura larvae than via Cd treated cabbages.

Macroinvertebrate identity mediates the effects of litter quality and microbial conditioning on leaf litter recycling in temperate streams.

Plant litter decomposition is an essential ecosystem function that contributes to carbon and nutrient cycling in streams. Aquatic shredders, mainly macroinvertebrates, can affect this process in various ways; they consume leaf litter, breaking it down into fragments and creating suitable habitats or resources for other organisms through the production of fine particulate organic matter (FPOM). However, measures of litter‐feeding traits across a wide range of aquatic macroinvertebrates are still rare. Here, we assessed the contributions of 11 species of freshwater macroinvertebrates to litter decomposition, by measuring consumption rate, FPOM production, and assimilation rate of highly decomposable (Alnus glutinosa) or poorly decomposable (Quercus robur) leaf litter types. In general, an increase in the quality of litter improved the litter consumption rate, and fungal conditioning of the leaf litter increased both the litter consumption rate and FPOM production. Macroinvertebrates specializing in leaf litter consumption also appeared to be the most sensitive to shifts in litter quality and the conditioning process. Contrary to expectations, the conditioning process did not increase the assimilation of low‐quality litter. There was a strong correlation between the relative consumption rate (RCR) of the two litter types, and the relative FPOM production (RFP) was strongly correlated to the RCR. These findings suggest a consistent relationship between RCR and macroinvertebrate identity that is not affected by litter quality, and that the RFP could be inferred from the RCR. The varying responses of the macroinvertebrate feeding traits to litter quality and the conditioning process suggest that the replacement of a shredder invertebrate species by another species could have major consequences for the decomposition process and the detritus‐based food web in streams. Further studies onto the importance of invertebrate identity and the effects of litter quality in a variety of freshwater ecosystems are needed to understand the whole ecosystem functioning and to predict its response to environmental changes.

Impact of elevated temperature and carbon dioxide on insect performance indices of Spodoptera litura fabricius

Effect of rise in minimum temperature (4 & 5°C) and carbon dioxide (CO2) concentration (400 & 500 ppm) was studied on food consumption and nutritional indices of Spodoptera litura on cabbage. The food consumption, consumption index (CI) and approximate digestibility (AD) showed a respective increase of 20, 8.9 and 4.7 per cent with elevated CO2 concentrations while efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), relative consumption rate (RCR), larval weight gain and pupal weight decreased by 8.50, 27, 26.6, 24.59 and 20.97 per cent respectively. Food consumption, CI, AD, ECI and pupal weight values increased by 43.23, 50.83, 22, 19.66 and 11.93 per cent with increase in minimum temperature by 5°C whereas ECD, RCR and larval weight gain decreased by 20.28, 35.89 and 25.16 per cent. Present studies indicated that under elevated temperature and CO2 regimes, the damage caused by S. litura on crops would increase.

Management of <i>Helicoverpa armigera</i> (Lepidoptera: Noctuidae) by Nutritional Indices and Botanical Extracts of <i>Millettia ferruginea</i> and <i>Azadirachta indica</i>

The development of hosts that are resistant and evaluation of botanical extracts to H. armigera Hubner (Lepidoptera: Noctuidae) is crucial for sustainable management, yet very limited in Ethiopia. Therefore, this study was done to identify alternative methods to insecticide control through host consumption study and botanical extracts. The performance of third-fifth larval stages of H. armigera on three host plant varieties including chickpea, tomato and faba bean and botanical extracts against the third larval instars and oviposition deterrence was studied under laboratory condition (22°C ± 2°C, 55% ± 5% RH, 12:12 L: D photoperiod). Significant differences were found in the efficiency of conversion of ingested food (ECI%) (F = 80.06; df = 6, 2; p < 0.05) and efficiency of conversion of digested food (ECD%) (F = 175.91; df = 6, 2; p < 0.05) values of H. armigera reared on the three host plant varieties of the whole larval instars. The minimum relative consumption rate (RCR) (11.271 ± 0.328) and maximum approximate digestibility (AD) (177.9 ± 1.928) values of the whole larval instars were on Dagaga and Koshari, respectively. The values of relative growth rate (RGR), ECI% and ECD% of the whole larval instars were highest on chickpea varieties and lowest on tomato Koshari. Among chickpea varieties, Habru was relatively resistant to larval instars of H. armigera. Botanical extracts at 50% neem oil (NO), 5% birbira seed extract (BSE) and 5% neem seed extract (NSE) (18.4%) resulted superior in larval mortality however, statistically not different. At both 5% and 2.5% concentration level of botanical extracts the minimum larval mortality was recorded from neem leaf extract (NLE). Maximum numbers of eggs were laid on control treatments and the minimum eggs were on 5% BSE. The deterrent effect of 50% neem oil was stronger (ODI = 17.66%) than that of 5% BSE (ODI = 14%) which is statistically similar value with 5% NSE (ODI = 13%). In conclusion, the result indicated that use of Habru chickpea variety with 50% NO was very effective in controlling both the larvae and deterring the adults of H. armigera from egg lying. These measures could be important in the wider managements of H. armigera by integrating host resistance and botanical extracts.

Chemical composition and insecticidal activity Mentha piperita L. essential oil against the cowpea seed beetle Callosobruchus maculatus F. (Coleoptera: Bruchidae)

Antifeedant activity of plant extract from Mentha piperita was tested against the cowpea seed beetle, Callosobruchus maculatus. Dry ground plant was subjected to hydrodistillation using a Clevenger-type apparatus. The resulting oil contained menthone (28.9%), menthol (28.5%), and pulegone (6.9%) as the major compounds. LC50 of M. piperita essential oil was 25.70 μL/L air and mortality increased as the doses of essential oil increased. LT50 values were 3.29, 2.74 and 1.89 h at 100, 200 and 500 μL/L air, respectively. The results of persistence test of oil revealed that essential oil of M. piperita on C. maculatus adults was 5.44 days. It was clear from the repellency index that M. piperita essential oil has strong repellency at 90, 180 and 360 μL/L air concentration. The results showed that M. piperita essential oil has significantly affected the relative growth rate, relative consumption rate and feeding deterrence index of C. maculatus adults and it was concentration-dependent. The efficiency of conversion of ingested food has decreased while the concentrations are not statistically different at 5% level compared to the control group. It seems that essential oil can be used as low-risk insecticides.

Fe(Ox)3]3- complex as a photodegradation agent at neutral pH: Advances and limitations

In the present work advances and limitations in the application of Fe(III)-oxalate complexes (namely, [Fe(Ox)3]3-) to the photodegradation of a model persistent organic contaminant - 2,4-dichlorophenoxybutanoic acid (2,4-DB) in neutral aqueous solutions were systematically investigated for the first time. It has been shown that the efficiency of [Fe(Ox)3]3- system greatly depends on the initial concentrations of oxalate ion due to the fast consumption of the ligand during photodegradation process leading to the formation of photochemically less active Fe(III) species. Efficiency of Fe(Ox)33− system normalized to UVA absorption at the excitation wavelength is practically independent on [Fe(III)]. Thus, it is highly probable that concentrations of Fe(III) as low as < 10−5 M could be applied in water treatment procedures using reactors with very long optical path. The system also keeps high efficiency at low concentration of pollutant (<10−5 M) though this results in higher relative consumption rate of Fe(III) and oxalate ions.

Determinants of submerged macrophytes palatability to grass carp Ctenopharyngodon idellus

Submerged macrophytes reestablishment is one of key processes in restoration of water ecological system. However, adverse effect caused by grass carp on macrophyte communities is existed during the process of ecological restoration. At present, little is known about determinants of submerged macrophytes palatability to grass carp. In this study, we measured the relative consumption rates (RCR) of grass carp on four species of submerged macrophytes Hydrilla verticillata, Vallisneria natans, Ceratophyllum demersum, and Myriophyllum spicatum, analysed the correlation between macrophytes traits and RCR, then investigated the kinds of flavonoids in four species of submerged macrophytes and their effects on the palatability for grass carp. The results showed that RCR of grass carp on H. verticillata and V. natans were much higher than C. demersum and M. spicatum. And for each submerged macrophyte, RCR of grass carp declined in the order of July>October>May. Stepwise multiple liner regression analyses showed that water temperature and protein were positively correlated, and flavonoids were negatively correlated, with RCR of grass carp. Rutin, quercitrin, quercetin and kaempferol, as the typical kinds of flavonoids, were in different contents in four kinds of macrophytes. And rutin, quercetin and kaempferol can deter grass carp feeding. These results conducted that grass carp favoured macrophytes with high protein and ate less macrophytes with high flavonoids. And it is helpful to provide fundamental basis for administrators to select appropriate macrophytes in restoration of water ecological system.

Interactive effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on the fitness and breeding of the amphipod Gammarus locusta.

Given the lack of knowledge regarding climate change-chemical exposure interactions, it is vital to evaluate how these two drivers jointly impact aquatic species. Thus, for the first time, we aimed at investigating the combined effects of increased temperature, pCO2 and the synthetic progestin levonorgestrel on survival, growth, consumption rate and reproduction of the amphipod Gammarus locusta. For that, a full factorial design manipulating temperature [ambient temperature and warming (+4°C)], pCO2 [normocapnia and hypercapnia (Δ pH 0.5 units)] and the progestin levonorgestrel (LNG: L1 - 10ngLL-1 and L2 - 1000ngLL-1, control - no progestin and solvent control - vehicle ethanol (0.01%)) was implemented for 21 days. G.locusta was strongly negatively affected by warming, experiencing higher mortality rates (50-80%) than in any other treatments. Instead, growth rates were significantly affected by interactions of LNG with temperature and pCO2. It was observed, in the short-term (7d) that under ambient temperature (18°C) and hypercapnic conditions (pH 7.6), the LNG presence promoted the amphipod's growth, while in the medium-term (21d) this response was not observed. Relative consumption rates (RCRs), during the first week were higher than in the third week. Furthermore, in the first week, RCRs were negatively affected by higher temperature while in the third week, RCRs were negatively affected by acidification. Furthermore, it was observed a negative effect of higher temperature and acidification on G.locusta fecundity, contrarily to LNG. Concluding, the impact of increased temperature and pCO2 was clearly more adverse for the species than exposure to the synthetic progestin, however, some interactions between the progestin and the climate factors were observed. Thus, in a future scenario of global change, the presence of LNG (and other progestins alike) may modulate to a certain level the effects of climate drivers (and vice-versa) on the gammarids fitness and reproduction.

Elevated CO2 and temperature alter development and food utilization of Spodoptera litura fed on resistant soybean

AbstractEffects of elevated atmospheric CO2 (elevated CO2 vs. ambient CO2) and temperature (+0.67–0.79°C vs. ambient temperature) on the developmental life cycle of Spodoptera litura and the food utilization of the fourth‐instar larvae fed on soybean (resistant cultivar Lamar vs. susceptible landrace JLNMH) grown in open‐top chambers were studied from 2013 to 2015. The results indicated that: (i) compared with ambient CO2, elevated CO2 significantly prolonged the duration of larva and pupa, and adult longevity; significantly decreased the pupation rate, pupal weight, fecundity, the relative growth rate (RGR), efficiency of conversion of ingested food (ECI) and efficiency of conversion of digested food (ECD); and increased the relative consumption rate (RCR) and approximate digestibility (AD). (ii) Compared with ambient temperature, elevated temperature significantly shortened the duration of larva and pupa; significantly decreased the pupal weight; and increased the RGR, RCR, ECD and ECI. (iii) Compared with the susceptible soybean accession JLNMH, the resistant soybean cultivar Lamar significantly prolonged the duration of larva and pupa; significantly decreased the pupation rate, pupal weight, adult longevity, fecundity and RGR, RCR and AD; and increased the indexes of ECD. (iv) At elevated temperature, S. litura fed on resistant vs. susceptible cultivars showed opposite trends in the RGR, RCR, AD, ECD and ECI. In addition, elevated temperature under elevated CO2 significantly decreased the RGR (2014), ECD (2013 &amp; 2014) and ECI (2013) and increased the AD (2013 &amp; 2014) compared with other treatment combinations when S. litura fed on Lamar. Future climatic change of temperature and CO2 concentration would likely affect growth and food utilization of S. litura, with increased food intake, but the reduced fecundity may compensate for the increased food consumption, resulting in no significant reduction in insect‐induced yield loss in soybean production. Nevertheless, use of insect resistant soybean cultivars will aid in ecological management of S. litura and reduce the insecticide load in soybean production.

Factors affecting palatability of four submerged macrophytes for grass carp Ctenopharyngodon idella.

Grass carp can weaken the growth and reproductive capacity of submerged macrophytes by consuming valuable tissues, but factors affecting palatability of submerged macrophytes for grass carp rarely are considered. In this study, relative consumption rate of grass carp with regard to submerged macrophytes was in the following order: Hydrilla verticillata > Vallisneria natans > Ceratophyllum demersum > Myriophyllum spicatum. Firmness of macrophytes was in the following order: M. spicatum > C. demersum > H. verticillata = V. natans, whereas shear force was M. spicatum > C. demersum > H. verticillata > V. natans. After crude extracts of M. spicatum were combined with H. verticillata, grass carp fed on fewer macrophyte pellets that contained more plant secondary metabolites (PSMs). This indicated that structure and PSMs affected palatability of macrophytes.PSMs do not contribute to reduction in palatability through inhibition of intestinal proteinases activity, but they can cause a decrease in the abundance of Exiguobacterium, Acinetobacter-yielding proteases, lipases, and cellulose activity, which in turn can weaken the metabolic capacity of grass carp and adversely affect their growth. Thus, the disadvantages to the growth and development of grass carp caused by PSMs may drive grass carp to feed on palatable submerged macrophytes with lower PSMs.

Evaluation of Bacillus vallismortis (Bacillales: Bacillaceae) R2 as insecticidal agent against polyphagous pest Spodoptera litura (Lepidoptera: Noctuidae).

The insecticidal potential of cells and acid-precipitated biomolecules (APB) of Bacillus vallismortis (Roberts) (Bacillales: Bacillaceae) R2 was evaluated against polyphagous pest Spodoptera litura. The intact cells of isolate R2 and its APB preparation significantly increased larval mortality. Both cells and APB significantly delayed the development and reduced adult emergence of S. litura. The toxicity of isolate R2 was evident from the emergence of morphologically deformed adults with crumpled and underdeveloped wings. The nutritional physiology of larvae fed on APB-supplemented diet was also adversely affected resulting in significant reduction of relative growth and consumption rate as well as efficiency of conversion of ingested and digested food. Thus, the intact viable cells and APB of B. vallismortis R2 may serve as environmental-friendly alternatives to chemical insecticides.

Event-Associated Oxygen Consumption Rate Increases ca. Five-Fold When Interictal Activity Transforms into Seizure-Like Events In Vitro.

Neuronal injury due to seizures may result from a mismatch of energy demand and adenosine triphosphate (ATP) synthesis. However, ATP demand and oxygen consumption rates have not been accurately determined, yet, for different patterns of epileptic activity, such as interictal and ictal events. We studied interictal-like and seizure-like epileptiform activity induced by the GABAA antagonist bicuculline alone, and with co-application of the M-current blocker XE-991, in rat hippocampal slices. Metabolic changes were investigated based on recording partial oxygen pressure, extracellular potassium concentration, and intracellular flavine adenine dinucleotide (FAD) redox potential. Recorded data were used to calculate oxygen consumption and relative ATP consumption rates, cellular ATP depletion, and changes in FAD/FADH2 ratio by applying a reactive-diffusion and a two compartment metabolic model. Oxygen-consumption rates were ca. five times higher during seizure activity than interictal activity. Additionally, ATP consumption was higher during seizure activity (~94% above control) than interictal activity (~15% above control). Modeling of FAD transients based on partial pressure of oxygen recordings confirmed increased energy demand during both seizure and interictal activity and predicted actual FAD autofluorescence recordings, thereby validating the model. Quantifying metabolic alterations during epileptiform activity has translational relevance as it may help to understand the contribution of energy supply and demand mismatches to seizure-induced injury.

Gut microbiota dysbiosis associated with glucose metabolism disorders and the metabolic syndrome in older adults.

Obesity and associated metabolic disorders have become highly prevalent diseases worldwide, and the human gut microbiota, due to its influence on host energy metabolism, has been attributed an important role therein. This pilot study explores host-microbiota relationships in men and women affected by various types of glucose metabolism disorder. Among 20 individuals aged 58 to 71 years with either normal glucose tolerance, prediabetes, or type 2 diabetes mellitus the gut bacterial communities were compared based on barcoded 454 sequencing of 16S rRNA genes amplified from stool samples. We found that specific microbiota groups were relatively enriched or reduced in different metabolic states. Further, positive or negative associations with clinical manifestations of metabolic disease suggest that these organisms indicate and possibly contribute to metabolic impairment or health. For instance, a higher prevalence of Erysipelotrichaceae and Lachnospiraceae was found associated with metabolic disorders, and the Holdemania and Blautia genera correlated with clinical indicators of an impaired lipid and glucose metabolism. The Bacteroidetes and groups therein, by contrast, displayed inverse relationships with metabolic disease parameters and were found relatively enriched in participants not diagnosed with metabolic syndrome or obesity. Further, the prevalence of specific Clostridia and Rikenellaceae members also pointed towards a healthier metabolic state. Links with diet as an intermediate factor included positive and negative associations of Lachnospiraceae with relative consumption rates of fat and carbohydrates, respectively, and positive associations of Turicibacteraceae with the consumption of protein. Identifying critical roles of major gut microbiota components in metabolic disorders has important translational implications regarding the prevention and treatment of metabolic diseases by means of preventing or reversing dysbiosis and by controlling exacerbating diet and life style factors particularly in sensitive population groups.