Long-term changes in the diet of pike (Esox lucius), the top aquatic predator in a changing Windermere

1. Pike (Esox lucius) is a key and flexible piscivore in many fresh waters of the northern temperate zone, but no previous studies have provided a continuous long-term perspective on its diet in response to changing environmental conditions. Here, we describe its winter diet from 1976 to 2009 in the North and South Basins of the lake of Windermere, U.K., where climate change, eutrophication and species introductions have combined to induce fundamental changes in the fish community. 2. A total of 6637 adult pike (fork length 390 to 1090 mm) was examined and found to have consumed a total of 4436 fish prey of which 98% of individuals identifiable to species comprised native Arctic charr (Salvelinus alpinus), brown trout (Salmo trutta), perch (Perca fluviatilis) and pike and non-native roach (Rutilus rutilus). Over the 34-year study period, the dietary importance of the salmonids Arctic charr and brown trout decreased, while that of the percid perch, the esocid pike and particularly the cyprinid roach increased. These changes were particularly marked in the more eutrophicated South Basin of the lake. 3. The above chronological trends in species-specific contributions to the diet composition of pike had considerable overall impacts. In the 1970s, pike diet composition was dominated by Arctic charr and brown trout which together comprised 94% of the diet. In contrast, in the 2000s, these two species accounted for just 55% of the diet, with perch and roach now comprising 41%. 4. Recent changes observed in the Windermere fish community of a decrease in native salmonids and an increase in cyprinids are consistent with the generally expected effects of climate change in the northern temperature zone. Here, we have shown that they have led to corresponding changes in the diet composition of pike. In turn, this may have implications for lake’s food web structure through shortening food chain length from the primary producers to the top aquatic predator

Harvest-induced disruptive selection increases variance in fitness-related traits

The form of Darwinian selection has important ecological and management implications. Negative effects of harvesting are often ascribed to size truncation (i.e. strictly directional selection against large individuals) and resultant decrease in trait variability, which depresses capacity to buffer environmental change, hinders evolutionary rebound and ultimately impairs population recovery. However, the exact form of harvest-induced selection is generally unknown and the effects of harvest on trait variability remain unexplored. Here we use unique data from the Windermere (UK) long-term ecological experiment to show in a top predator (pike, Esox lucius) that the fishery does not induce size truncation but disruptive (diversifying) selection, and does not decrease but rather increases variability in pike somatic growth rate and size at age. This result is supported by complementary modelling approaches removing the effects of catch selectivity, selection prior to the catch and environmental variation. Therefore, fishing most likely increased genetic variability for somatic growth in pike and presumably favoured an observed rapid evolutionary rebound after fishery relaxation. Inference about the mechanisms through which harvesting negatively affects population numbers and recovery should systematically be based on a measure of the exact form of selection. From a management perspective, disruptive harvesting necessitates combining a preservation of large individuals with moderate exploitation rates, and thus provides a comprehensive tool for sustainable exploitation of natural resources

Cystathionine beta synthase deficiency and brain edema associated with methionine excess under betaine supplementation: Four new cases and a review of the evidence.

CBS deficient individuals undergoing betaine supplementation without sufficient dietary methionine restriction can develop severe hypermethioninemia and brain edema. Brain edema has also been observed in individuals with severe hypermethioninemia without concomitant betaine supplementation. We systematically evaluated reports from 11 published and 4 unpublished patients with CBS deficiency and from additional four cases of encephalopathy in association with elevated methionine. We conclude that, while betaine supplementation does greatly exacerbate methionine accumulation, the primary agent causing brain edema is methionine rather than betaine. Clinical signs of increased intracranial pressure have not been seen in patients with plasma methionine levels below 559 μmol/L but occurred in one patient whose levels did not knowingly exceed 972 μmol/L at the time of manifestation. While levels below 500 μmol/L can be deemed safe it appears that brain edema can develop with plasma methionine levels close to 1000 μmol/L. Patients with CBS deficiency on betaine supplementation need to be regularly monitored for concordance with their dietary plan and for plasma methionine concentrations. Recurrent methionine levels above 500 μmol/L should alert clinicians to check for clinical signs and symptoms of brain edema and review dietary methionine intake. Levels approaching 1000 μmol/L do increase the risk of complications and levels exceeding 1000 μmol/L, despite best dietetic efforts, should be acutely addressed by reducing the prescribed betaine dose

What is the microbiome of the human home?

There is currently little known about the range and diversity of microorganisms in the indoor home, particularly in the context of modern airtight homes. People spend a great deal of time in their homes, especially those at the extremes of age, and it is possible that the indoor microbiome could impact upon human health in ways not yet understood. This project aimed to systematically screen sites in 100 houses in the Lanarkshire community in order to determine the amount and type of cultivable aerobic bacteria and fungi in the home. It was hoped to be able to characterise the microbiome of the ‘normal’ home. Chosen sites were: indoor bathroom handle; telephone; kettle handle; bedside table; top of bedroom door; TV remote; toilet handle; and bedroom window sill (Table 1). These sites were screened using double-sided dipslides coated with nutrient and staphylococcal selective agars (Figure 1). Bacteria and fungi were quantified for each site and staphylococci and Gram- negative bacilli identified if possible. Each of the eight sampled sites revealed its own distinct microbiological character, both in the type and amount of cultivable microbes. Human pathogens, particularly S.aureus, were more likely to be associated with commonly touched sites such as TV remote, kettle handle and telephone. Whole houses also demonstrated unique microbiological characteristics, with morphologically similar and identifiable microbes observed at multiple sites within the same home. Each home thus displayed it own unique microbiome but with identifiable similarities between other homes according to site

Dietary intake is independently associated with the maximal capacity for fat oxidation during exercise

Background: Substantial interindividual variability exists in the maximal rate of fat oxidation (MFO) during exercise with potential implications for metabolic health. Although the diet can affect the metabolic response to exercise, the contribution of a self-selected diet to the interindividual variability in the MFO requires further clarification. Objective: We sought to identify whether recent, self-selected dietary intake independently predicts the MFO in healthy men and women. Design: The MFO and maximal oxygen uptake ([Image: see text]O(2) max) were determined with the use of indirect calorimetry in 305 healthy volunteers [150 men and 155 women; mean ± SD age: 25 ± 6 y; body mass index (BMI; in kg/m(2)): 23 ± 2]. Dual-energy X-ray absorptiometry was used to assess body composition with the self-reported physical activity level (SRPAL) and dietary intake determined in the 4 d before exercise testing. To minimize potential confounding with typically observed sex-related differences (e.g., body composition), predictor variables were mean-centered by sex. In the analyses, hierarchical multiple linear regressions were used to quantify each variable’s influence on the MFO. Results: The mean absolute MFO was 0.55 ± 0.19 g/min (range: 0.19–1.13 g/min). A total of 44.4% of the interindividual variability in the MFO was explained by the [Image: see text]O(2) max, sex, and SRPAL with dietary carbohydrate (carbohydrate; negative association with the MFO) and fat intake (positive association) associated with an additional 3.2% of the variance. When expressed relative to fat-free mass (FFM), the MFO was 10.8 ± 3.2 mg · kg FFM(−1) · min(−1) (range: 3.5–20.7 mg · kg FFM(−1) · min(−1)) with 16.6% of the variability explained by the [Image: see text]O(2) max, sex, and SRPAL; dietary carbohydrate and fat intakes together explained an additional 2.6% of the variability. Biological sex was an independent determinant of the MFO with women showing a higher MFO [men: 10.3 ± 3.1 mg · kg FFM(−1) · min(−1) (3.5–19.9 mg · kg FFM(−1) · min(−1)); women: 11.2 ± 3.3 mg · kg FFM(−1) · min(−1) (4.6–20.7 mg · kg FFM(−1) · min(−1)); P < 0.05]. Conclusion: Considered alongside other robust determinants, dietary carbohydrate and fat intake make modest but independent contributions to the interindividual variability in the capacity to oxidize fat during exercise. This trial was registered at clinicaltrials.gov as NCT02070055

Cystathionine beta synthase deficiency and brain edema associated with methionine excess under betaine supplementation: Four new cases and a review of the evidence

CBS deficient individuals undergoing betaine supplementation without sufficient dietary methionine restriction can develop severe hypermethioninemia and brain edema. Brain edema has also been observed in individuals with severe hypermethioninemia without concomitant betaine supplementation. We systematically evaluated reports from 11 published and 4 unpublished patients with CBS deficiency and from additional four cases of encephalopathy in association with elevated methionine. We conclude that, while betaine supplementation does greatly exacerbate methionine accumulation, the primary agent causing brain edema is methionine rather than betain