Understanding stoichiometric constraints on growth using resource use efficiency imbalances.

Growth is a function of the net accrual of resources by an organism. Energy and elemental contents of organisms are dynamically linked through their uptake and allocation to biomass production, yet we lack a full understanding of how these dynamics regulate growth rate. Here, we develop a multivariate imbalance framework, the growth efficiency hypothesis, linking organismal resource contents to growth and metabolic use efficiencies, and demonstrate its effectiveness in predicting consumer growth rates under elemental and food quantity limitation. The relative proportions of carbon (%C), nitrogen (%N), phosphorus (%P), and adenosine triphosphate (%ATP) in consumers differed markedly across resource limitation treatments. Differences in their resource composition were linked to systematic changes in stoichiometric use efficiencies, which served to maintain relatively consistent relationships between elemental and ATP content in consumer tissues and optimize biomass production. Overall, these adjustments were quantitatively linked to growth, enabling highly accurate predictions of consumer growth rates.

Effect of digestible protein on intermediate metabolism, hepatic enzyme activities, energy reserves, and growth performance of pacu (Piaractus mesopotamicus) in the finishing growth phase.

This study investigated the effect of different levels of digestible protein (DP) on blood metabolites, hepatic enzyme activity of glycolysis and amino acid metabolism, energy reserves, and the production characteristics of pacu (Piaractus mesopotamicus) during the finishing growth phase. Six semi purified and isoenergetic diets, containing 16.3, 20.1, 23.8, 27.2, 31.5, and 34.8% of balanced DP, provided with essential amino acid balance, were hand-fed to pacu (1100.0 ± 10.3 g, initial weight) three times daily for 7 weeks. The experiment consisted of six treatments, with three randomly arranged replicates (tanks) per treatment. The data obtained from this experiment were analyzed by one-way analysis of variance (ANOVA), and significant differences (p < 0.05) between treatments were determined using Tukey's test. Blood metabolites, except serum ammonia and the hepatic enzymes activities of glycolysis and amino acid metabolism, except hexokinase activity were affected (p < 0.05) by balanced DP. The energy reserve indices, except hepatic total lipid content, were also found associated (p < 0.05) with balanced DP. The test diets significantly (p < 0.05) affected growth performance parameters. Higher dietary proteins led to a greater energy uptake by fish from the protein in feed. Overall, fish fed the intermediate level (23.8%) of balanced DP with digestible energy of 17.95 MJ kg-1 showed better production traits and physio-biochemical health markers. This information could help nutritionists and farmers to develop nutritionally balanced and economically and environmentally sustainable aquafeed for promoting healthy and sustainable production of pacu in intensive culture systems.

Larvicidal, growth inhibitory and biochemical effects of soil bacterium, Pseudomonas sp. EN4 against Spodoptera litura (Fab.) (Lepidoptera: Noctuidae).

BACKGROUND: Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae) also known as tobacco caterpillar, is one of the most serious polyphagous pests that cause economic losses to a variety of commercially important agricultural crops. Over the past few years, many conventional insecticides have been used to control this pest. However, the indiscriminate use of these chemicals has led to development of insecticide resistant populations of S. litura in addition to harmful effects on environment. Due to these ill effects, the emphasis is being laid on alternative eco-friendly control measures. Microbial control is one of the important components of integrated pest management. Thus, in search for novel biocontrol agents, the current work was carried out with the aim to evaluate the insecticidal potential of soil bacteria against S. litura. RESULTS: Among the tested soil bacterial isolates (EN1, EN2, AA5, EN4 and R1), maximum mortality (74%) was exhibited by Pseudomonas sp. (EN4). The larval mortality rate increased in a dose-dependent manner. Bacterial infection also significantly delayed the larval development, reduced adult emergence, and induced morphological deformities in adults of S. litura. Adverse effects were also detected on various nutritional parameters. The infected larvae showed a significant decrease in relative growth and consumption rate as well as efficiency of conversion of ingested and digested food to biomass. Histopathological studies indicated damage to the midgut epithelial layer of larvae due to the consumption of bacteria treated diet. The infected larvae also showed a significantly decreased level of various digestive enzymes. Furthermore, exposure to Pseudomonas sp. also caused DNA damage in the hemocytes of S. litura larvae. CONCLUSION: Adverse effects of Pseudomonas sp. EN4 on various biological parameters of S. litura indicate that this soil bacterial strain may be used as an effective biocontrol agent against insect pests.

Feeding responses and digestive function of Spodoptera littoralis (Boisd) on various leafy vegetables exhibit possible tolerance traits.

Spodoptera littoralis is a highly polyphagous pest that attacks numerous important crops in the world and causes substantial economic losses to agricultural production. In the present study, the effects of different leafy vegetables, including Purslane, Chives, Parsley, Basil, Dill, Coriander, and Mint, were investigated on feeding responses and enzymatic activities of S. littoralis under laboratory conditions. Furthermore, the total contents of the three major secondary metabolites (phenolics, anthocyanins, and flavonoids) in the studied vegetables were determined. Our findings showed that the lowest and the highest approximate digestibility were on Basil and Purslane, respectively. The highest values of efficiency of conversion of ingested and digested food were achieved in larvae fed on Chives and Coriander, respectively, whereas the lowest values were recorded after feeding on Purslane. The highest and lowest relative growth rates were in larvae reared on Dill and Purslane, respectively. Furthermore, the highest amylolytic and proteolytic activities were in larvae fed with Coriander and Dill, respectively, while the lowest activities of these enzymes were on Purslane. In addition, correlation analysis revealed significant correlations between feeding characteristics and enzymatic activity of S. littoralis with biochemical compounds of the studied leafy vegetables. Our results suggest that Coriander is a suitable host, while Purslane displayed tolerance traits against S. littoralis, which can be used in sustainable management programs aiming to reduce chemical inputs.

Ameliorative role of dietary acidifier potassium formate on growth metrics, blood chemistry, gut health and well-being indices of rohu, Labeo rohita fingerlings.

Organic acids and their derivatives have been attributed to growth and well-being improvement in fish when supplemented in their diets. Therefore, this study was conducted to evaluate the ameliorative role of potassium formate (PF) in rohu Labeo rohita fingerlings. A total of 240 healthy rohu fingerlings (9.0 ± 0.5 g ± SE) were randomly divided into four equal groups in triplicates. Fish were fed with isonitrogenous feeds: PF10 (10 g PF/kg), PF20 (20 g PF/kg) and PF30 (30 g PF/kg). Feed without PF supplementation served as control. The results indicated that the specific growth rate (SGR) and feed conversion ratio (FCR) were significantly (p<0.05) higher in PF10. Total serum globulin content was found significantly (p<0.05) elevated in PF10 after the bacterial challenge. Non-specific lysozyme activity was significantly higher (p<0.05) after the challenge. The digestive protease enzyme activity was significantly (p<0.05) improved in PF10 treatment. Additionally, the digestive morphology of the treated fish was seen to be improved. Greater villus area, increased villus number, reduced lumen space in the hindgut, reduced vacuolation in mucosal folds and proliferation of goblet cells-like changes were observed in the PF-supplemented fish. Significantly (p<0.05), a higher relative percentage of survival (RPS) was observed in PF10 and PF20 treatments. The study revealed that the dietary supplementation of rohu fingerlings with lower levels of potassium formate could enhance the nutritional efficiency and physiological activities of rohu fingerlings. This study serves as a baseline for future research on the application of formic acid derivatives and other acidifiers in carp culture.

The WeanCare nutritional intervention in institutionalized dysphagic older people and its impact on nursing workload and costs: A quasi-experimental study.

AIM: The aim of this study is to explore how a nutritional intervention that improves the biochemical and functional profile of dysphagic older people impacts on nursing workload and costs for nursing homes. BACKGROUND: Dysphagic institutionalized older people particularly at risk of malnutrition require more intensive support from nursing staff and higher costs for nursing homes. METHOD: This is an open pre-post longitudinal multicentre quasi-experimental study without a control group. RESULTS: There is a significant reduction in the number of enemas (from 3.51 to 1.11 enemas), with an average nursing workload reduction from 52 to 16 min per patient every month. Each nurse also spent 20 h less per patient every month spoon-feeding. This resulted in nursing staff cost savings. CONCLUSIONS: The nutritional intervention led to a significantly better quality of life for the patients manifested through increased independence and social engagement. This reduced workload for nursing staff and costs for nursing home administrators. IMPLICATIONS FOR NURSING MANAGEMENT: Sensitive, targeted nutritional interventions have the potential to improve nursing home residents' quality of life and enable a more efficient use of resources. This study revealed reduced workload and cost savings due to less time spent administering enemas and spoon-feeding, in addition to reduced malnutritional consequences.

Insect Sterol Nutrition: Physiological Mechanisms, Ecology, and Applications.

Insects, like all eukaryotes, require sterols for structural and metabolic purposes. However, insects, like all arthropods, cannot make sterols. Cholesterol is the dominant tissue sterol for most insects; insect herbivores produce cholesterol by metabolizing phytosterols, but not always with high efficiency. Many insects grow on a mixed-sterol diet, but this ability varies depending on the types and ratio of dietary sterols. Dietary sterol uptake, transport, and metabolism are regulated by several proteins and processes that are relatively conserved across eukaryotes. Sterol requirements also impact insect ecology and behavior. There is potential to exploit insect sterol requirements to (a) control insect pests in agricultural systems and (b) better understand sterol biology, including in humans. We suggest that future studies focus on the genetic mechanism of sterol metabolism and reverse transportation, characterizing sterol distribution and function at the cellular level, the role of bacterial symbionts in sterol metabolism, and interrupting sterol trafficking for pest control.

Gut Bacteria Mediate Nutrient Availability in Drosophila Diets.

Drosophila melanogaster gut microbes play important roles in host nutritional physiology. However, these associations are often indirect, and studies typically are in the context of specialized nutritional conditions, making it difficult to discern how microbiome-mediated impacts translate to physiologically relevant conditions, in the laboratory or nature. In this study, we quantified changes in dietary nutrients due to D. melanogaster gut bacteria on three artificial diets and a natural diet of grapes. We show that under all four diet conditions, bacteria altered the protein, carbohydrates, and moisture of the food substrate. An in-depth analysis of one diet revealed that bacteria also increased the levels of tryptophan, an essential amino acid encountered scarcely in nature. These nutrient changes result in an increased protein-to-carbohydrate (P:C) ratio in all diets, which we hypothesized to be a significant determinant of microbiome-mediated host nutritional physiology. To test this, we compared life history traits of axenic flies reared on the three artificial diets with increased P:C ratios or continuous bacterial inoculation. We found that while on some diets, an environment of nutritional plenitude had impacts on life history, it did not fully explain all microbiome-associated phenotypes. This suggests that other factors, such as micronutrients and feeding behavior, likely also contribute to life history traits in a diet-dependent manner. Thus, while some bacterial impacts on nutrition occur across diets, others are dictated by unique dietary environments, highlighting the importance of diet-microbiome interactions in D. melanogaster nutritional physiology.IMPORTANCE Both in the laboratory and in nature, D. melanogaster-associated microbes serve as nutritional effectors, either through the production of metabolites or as direct sources of protein biomass. The relationship between the microbiome and the resulting host nutritional physiology is significantly impacted by diet composition, yet studies involving D. melanogaster are performed using a wide range of artificial diets, making it difficult to discern which aspects of host-microbe interactions may be universal or diet dependent. In this study, we utilized three standard D. melanogaster diets and a natural grape diet to form a comprehensive understanding of the quantifiable nutritional changes mediated by the host microbial community. We then altered these artificial diets based on the observed microbe-mediated changes to demonstrate their potential to influence host physiology, allowing us to identify nutritional factors whose effects were either universal for the three artificial diets or dependent on host diet composition.

Compensatory changes in villus morphology of lactating Mus musculus in response to insufficient dietary protein.

Energetic challenges match intestinal size to dietary intake but less is known about how the intestine responds to specific macronutrient challenges. We examined how intestinal size responds to insufficient dietary protein at the microscopic level. Villi, enterocytes and surface area were measured across the length of the small intestine in non-reproductive and lactating Mus musculus fed isocaloric control or protein-deficient diets. Lactating mice on the protein-deficient diet exhibited a 24% increase in villus height and a 30% increase in enterocyte width in the proximal small intestine and an overall similar increase in surface area; on the control diet, changes in villus height were localized in the mid region. Flexibility localized to the proximal small intestine suggests that enterokinase, a localized enzyme, may be a candidate enzyme that promotes compensation for a protein-deficient diet. Such flexibility could allow species to persist in the face of anthropogenically induced changing dietary profiles.

Food assistance programs and income are associated with the diet quality of grocery purchases for households consisting of women of reproductive age or young children.

Women's diet quality during reproductive years and children's diet quality during early life influence long term health. Few studies have evaluated the impact of food assistance programs and income on the diet quality of grocery purchases made by households consisting of women of reproductive age and young children. We used data from the Food Acquisition and Purchase Survey 2012-2013 (FoodAPS) to evaluate how household income, Special Supplemental Nutrition Assistance Program for Women, Infants and Children (WIC) participation, and Supplemental Nutrition Assistance Program (SNAP) participation are related to the diet quality of grocery purchases made by households that include women of reproductive age or young children (n = 2436). The diet quality of household grocery purchases was assessed with the Healthy Eating Index (HEI) 2015. HEI-2015 total score (0-100) and component scores were evaluated according to household income (eligible for WIC: income-to-poverty ratio ≤ 185%; ineligible for WIC: income-to-poverty ratio > 185%) and WIC, SNAP, and WIC + SNAP participation. Median HEI-2015 total score was lowest among SNAP households and highest among income ineligible for WIC and WIC households (47.2 and 54.1, respectively). Compared to income ineligible for WIC households, WIC + SNAP and SNAP households had lower HEI-2015 whole fruit (ß = -0.30, 95% CI: -0.59, -0.01 and ß = -0.41, 95% CI: -0.63, -0.20, respectively) and total vegetable scores (ß = -0.58, 95% CI: -0.83, -0.32 and ß = -0.27, 95% CI: -0.45, -0.08, respectively). The diet quality of grocery purchases in this population varies according to household income and food assistance participation.

Prenatal dietary exposures and offspring body size from 6 months to 18 years: A systematic review.

BACKGROUND: In utero dietary exposures may influence childhood obesity. OBJECTIVES: To evaluate the relationship between prenatal dietary exposures and offspring body size from 6 months to 18 years. DATA SOURCES: Articles were identified in PubMed and Web of Science (January 2010-March 2018) using the PRISMA guidelines. Additional studies were identified through a reference review of articles that met the inclusion criteria and related reviews. STUDY SELECTION: Prospective cohort studies that assessed dietary patterns, foods, macronutrients, or beverages during healthy pregnancy and offspring body size. The extraction of articles was done using predefined data fields. SYNTHESIS: One author extracted all information and evaluated bias with the NHLBI's Quality Assessment Tool. RESULTS: A total of 851 research articles were evaluated. Twenty-one studies assessing dietary patterns, macronutrients, foods, and beverages met inclusion criteria. Consumption of a Mediterranean dietary pattern during pregnancy was associated with reduced body size, while refined carbohydrates were associated with offspring obesity. No association was observed between data-driven dietary patterns and offspring body size, as well as a pro-inflammatory diet pattern and offspring body size. Mixed and null findings were observed for the relationship between total carbohydrates, n-3 polyunsaturated fatty acids, protein, sugar-sweetened beverages, and artificially sweetened beverages and offspring body size. CONCLUSIONS: Adhering to a Mediterranean diet and limiting refined carbohydrates during pregnancy may influence offspring body size between 6 months and 18 years. The diverging results that exist between studies highlight the complexity of this topic.

Variation in the pH of experimental diets affects the performance of Lymantria dispar asiatica larvae and its gut microbiota.

To study dietary pH effects on Lymantria dispar asiatica larvae and provide a theoretical basis for its control in different forests, phosphate buffers (PBs) of pH 6, 7, and 8 were used to prepare experimental diets. The diet prepared with pH 6 PB was named as DPB6, with pH 8 PB as DPB8, and with pH 7 PB as DPB7 (control). The dietary pH was 5.00 in DPB6, 6.05 in control, and 6.50 in DPB8. After feeding on the diets with different pH values for 84 hr, fourth-instar caterpillars were randomly collected. Growth and various physiological traits were determined and 16S recombinant DNA sequencing was performed using the intestinal microflora of surviving larvae. Results showed that the mortality was 30% in DPB6, and 10% in DPB8, while no mortality was observed in control. The partial least squares discriminant analyses suggested that diets prepared with PB of different pH resulted in different food intake, amount of produced feces, weight gain, digestive enzyme activities, and antioxidant enzyme activities in larvae. Interestingly, both the highest weight gain and the lowest total antioxidant capacities were seen in control larvae. Results also showed that the larval gut microbiota community structure was significantly affected by dietary pH. Moreover, linear discriminant analysis effect size suggested that the family Acetobacteraceae in control, genus Prevotella in DPB8, and genus Lactococcus, family Flavobacteriaceae, family Mitochondria, and family Burkholderiaceae in DPB6 contributed to the diversity of the larval gut microbial community.

Enhanced effects of dietary tannic acid with chlorantraniliprole on life table parameters and nutritional physiology of Spodoptera exigua (Hübner).

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) is a highly polyphagous pest which causes considerable economic losses to cotton and many vegetable crops. Tannins are among the most important secondary metabolites in cotton plants. We show that tannic acid enhances the toxic effect of chlorantraniliprole on S. exigua when presented in combination. Bioassays using third-instar S. exigua larvae on an artificial diet showed that consumption of tannic acid with chlorantraniliprole at the concentration of (2 mg/g and LC50 0.018 mg/L) had higher toxicity when compared to either chlorantraniliprole or tannic acid alone (LC50 0.027 mg/L). The diet containing tannic acid with chlorantraniliprole significantly prolonged larval and pupal developmental time and extended mean generation time and total pre-oviposition period compared to either chemical alone. Moreover, fecundity, survival rate, reproductive value, intrinsic rate of increase, finite rate of increase and net reproduction rate declined significantly when exposed to the combined treatment. No difference was observed between tannic acid and the control. Meanwhile, tannic acid with chlorantraniliprole had markedly antifeedant effects; causing significant decline in the relative growth rate (RGR), the relative consumption rate (RCR), the efficiency of conversion of ingested food (ECI), the efficiency of conversion of digested food and an increase in the approximate digestibility (AD) compared to either chemical alone. Tannic acid with chlorantraniliprole also decreased the insect's carbohydrate, lipid and protein contents significantly. The results showed that the interaction between tannic acid and chlorantraniliprole on the growth inhibition of larvae was additive and tannic acid increased the toxicity of chlorantraniliprole to insects. The results of this study provide information useful in integrated pest management programs for S. exigua and show that tannic acid combined with chlorantraniliprole may be a route to reducing the use of synthetic pesticides.

Seagrass digestion by a notorious 'carnivore'.

What an animal consumes and what an animal digests and assimilates for energetic demands are not always synonymous. Sharks, uniformly accepted as carnivores, have guts that are presumed to be well suited for a high-protein diet. However, the bonnethead shark (Sphyrna tiburo), which is abundant in critical seagrass habitats, has been previously shown to consume copious amounts of seagrass (up to 62.1% of gut content mass), although it is unknown if they can digest and assimilate seagrass nutrients. To determine if bonnetheads digest seagrass nutrients, captive sharks were fed a 13C-labelled seagrass diet. Digestibility analyses, digestive enzyme assays and stable isotope analyses were used to determine the bonnethead shark's capacity for digesting and assimilating seagrass material. Compound-specific stable isotope analysis showed that sharks assimilated seagrass carbon (13.6 ± 6.77‰ δ13C mean ± s.d. for all sharks and all amino acid types analysed) with 50 ± 2% digestibility of seagrass organic matter. Additionally, cellulose-component-degrading enzyme activities were detected in shark hindguts. We show that a coastal shark is digesting seagrass with at least moderate efficiency, which has ecological implications due to the stabilizing role of omnivory and nutrient transport within fragile seagrass ecosystems.

Childhood dietary trajectories and adolescent cardiovascular phenotypes: Australian community-based longitudinal study.

OBJECTIVE: With the intention to inform future public health initiatives, we aimed to determine the extent to which typical childhood dietary trajectories predict adolescent cardiovascular phenotypes. DESIGN: Longitudinal study. Exposure was determined by a 4 d food diary repeated over eight waves (ages 4-15 years), coded by Australian Dietary Guidelines and summed into a continuous diet score (0-14). Outcomes were adolescent (Wave 8, age 15 years) blood pressure, resting heart rate, pulse wave velocity, carotid intima-media thickness, retinal arteriole-to-venule ratio. Latent class analysis identified 'typical' dietary trajectories from childhood to adolescence. Adjusted linear regression models assessed relationships between trajectories and cardiovascular outcomes, adjusted for a priori potential confounders. SETTING: Community sample, Melbourne, Australia. SUBJECTS: Children (n 188) followed from age 4 to 15 years. RESULTS: Four dietary trajectories were identified: unhealthy (8 %); moderately unhealthy (25 %); moderately healthy (46 %); healthy (21 %). There was little evidence that vascular phenotypes associated with the trajectories. However, resting heart rate (beats/min) increased (ß; 95 % CI) across the healthy (reference), moderately healthy (4·1; -0·6, 8·9; P=0·08), moderately unhealthy (4·5; -0·7, 9·7; P=0·09) and unhealthy (10·5; 2·9, 18·0; P=0·01) trajectories. CONCLUSIONS: Decade-long dietary trajectories did not appear to influence macro- or microvascular structure or stiffness by mid-adolescence, but were associated with resting heart rate, suggesting an early-life window for prevention. Larger studies are needed to confirm these findings, the threshold of diet quality associated with these physiological changes and whether functional changes in heart rate are followed by phenotypic change.

Wheat cultivars affecting life history and digestive amylolytic activity of Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae).

The life history and digestive α-amylase activity of the Angoumois grain moth, Sitotroga cerealella Olivier (Lepidoptera: Gelechiidae) were studied on six wheat cultivars (Arg, Bam, Nai 60, Pishtaz, Sepahan and Shanghai) at 25 ± 1°C, relative humidity of 65 ± 5% and a photoperiod of 16:8 (L:D) h. A delay in the developmental time of S. cerealella immature stages was detected when larvae were fed on cultivar Sepahan. The maximum survival rate of immature stages was seen on cultivar Bam (93.33 ± 2.10%), and the minimum rates were on cultivars Nai 60 (54.66 ± 2.49%) and Sepahan (49.33 ± 4.52%). The highest realized fecundity and fertility were recorded for females which came from larvae fed on cultivar Bam (93.30 ± 2.10 eggs/female and 91.90 ± 3.10%, respectively); and the lowest ones were observed for females which came from larvae fed on cultivar Sepahan (49.30 ± 4.50 eggs/female and 67.4 ± 11.1%, respectively). The heaviest male and female weights of S. cerealella were observed on cultivar Bam (2.97 ± 0.02 and 4.80 ± 0.01 mg, respectively). The highest amylolytic activity of the fourth instar was detected on cultivar Bam (0.89 ± 0.04 mg maltose min-1), which had the maximum mean hundred-wheat weight (5.92 ± 0.19 g). One α-amylase isozyme was detected in the midgut extracts from the fourth instar larvae fed on different wheat cultivars, and the highest intensity was found in larvae fed on cultivar Bam. Correlation analyses showed that very high correlations existed between the immature period, fecundity and fertility on one side and inhibition of α-amylase, soluble starch content and hundred-wheat weight on the other. According to the obtained results, cultivar Sepahan is an unfavorable host for the feeding and development of S. cerealella.

Evaluation of sublethal effects of polymer-based essential oils nanoformulation on the german cockroach.

The German cockroach, Blattella germanica (L.), is a serious household and public health pest worldwide. The aim of the present study was to evaluate the sublethal activity of polymer-based essential oils (EOs) nanoparticles (NPs) on adults of B. germanica. The LC50 and LC25 for contact toxicity were determined. To evaluate the repellency of EOs and NPs at LC25, a software was specially created in order to track multiple insects on just-recorded videos, and generate statistics using the obtained information. The effects of EOs and NPs at LC25 and LC50 on the nutritional physiology were also evaluated. The results showed that NPs exerted sublethal effects on the German cockroach, since these products enhance the repellent effects of the EOs and negatively affected the nutritional indices and the feeding deterrence index.

Differential transcriptomic responses of ancient and modern Daphnia genotypes to phosphorus supply.

Little is known about the role of transcriptomic changes in driving phenotypic evolution in natural populations, particularly in response to anthropogenic environmental change. Previous analyses of Daphnia genotypes separated by centuries of evolution in a lake using methods in resurrection ecology revealed striking genetic and phenotypic shifts that were highly correlated with anthropogenic environmental change, specifically phosphorus (P)-driven nutrient enrichment (i.e. eutrophication). Here, we compared the transcriptomes of two ancient (~700-year-old) and two modern (~10-year-old) genotypes in historic (low P) and contemporary (high P) environmental conditions using microarrays. We found considerable transcriptomic variation between 'ancient' and 'modern' genotypes in both treatments, with stressful (low P) conditions eliciting differential expression (DE) of a larger number of genes. Further, more genes were DE between 'ancient' and 'modern' genotypes than within these groups. Expression patterns of individual genes differed greatly among genotypes, suggesting that different transcriptomic responses can result in similar phenotypes. While this confounded patterns between 'ancient' and 'modern' genotypes at the gene level, patterns were discernible at the functional level: annotation of DE genes revealed particular enrichment of genes involved in metabolic pathways in response to P-treatments. Analyses of gene families suggested significant DE in pathways already known to be important in dealing with P-limitation in Daphnia as well as in other organisms. Such observations on genotypes of a single natural population, separated by hundreds of years of evolution in contrasting environmental conditions before and during anthropogenic environmental changes, highlight the important role of transcriptional mechanisms in the evolutionary responses of populations.

A millennial-scale chronicle of evolutionary responses to cultural eutrophication in Daphnia.

For an accurate assessment of the anthropogenic impacts on evolutionary change in natural populations, we need long-term environmental, genetic and phenotypic data that predate human disturbances. Analysis of c. 1600 years of history chronicled in the sediments of South Center Lake, Minnesota, USA, revealed major environmental changes beginning c. 120 years ago coinciding with the initiation of industrialised agriculture in the catchment area. Population genetic structure, analysed using DNA from dormant eggs of the keystone aquatic herbivore, Daphnia pulicaria, suggested no change for c. 1500 years prior to striking shifts associated with anthropogenic environmental alterations. Furthermore, phenotypic assays on the oldest resurrected metazoan genotypes (potentially as old as c. 700 years) indicate significant shifts in phosphorus utilisation rates compared to younger genotypes. Younger genotypes show steeper reaction norms with high growth under high phosphorus (P), and low growth under low P, while 'ancient' genotypes show flat reaction norms, yet higher growth efficiency under low P. Using this resurrection ecology approach, environmental, genetic and phenotypic data spanning pre- and post-industrialised agricultural eras clearly reveal the evolutionary consequences of anthropogenic environmental change.

Dry blood spots as a sampling strategy to identify insulin resistance markers during a dietary challenge.

This study aimed to identify markers of postprandial dysglycemia in the blood of self-described healthy individuals using dry blood spots (DBS) as a sampling strategy. A total of 54 volunteers, including 31 women, participated in a dietary challenge. They consumed a high-fat, high-sugar mixed meal and underwent multiple blood sampling over the course of 150 min to track their postprandial responses. Blood glucose levels were monitored with a portable glucometer and individuals were classified into two groups based on the glucose area under the curve (AUC): High-AUC (H-AUC) and Low-AUC (L-AUC). DBS sampling was performed at the same time points as the assessment of glycemia using Whatman 903 Protein Saver filter paper. A gas chromatography-mass spectrometry-based metabolite profiling was conducted in the DBS samples to assess postprandial changes in blood metabolome. Higher concentrations of metabolites associated with insulin resistance were observed in individuals from the H-AUC group, including sugars and sugar-derived products such as fructose and threonic acid, as well as organic acids and fatty acids such as succinate and stearic acid. Several metabolites detected in the GC-MS analysis remained unidentified, indicating that other markers of hyperglycemia remain to be discovered in DBS. Based on these observations, we demonstrated that the use of DBS as a non-invasive and inexpensive sampling tool allows the identification of metabolites markers of dysglycemia in the postprandial period.