Is lipid correction necessary in the stable isotope analysis of fish tissues?

RATIONALE: Stable isotope analysis (SIA) is a powerful tool for examining diet and food-web dynamics. SIA assumes "you are what you eat" relative to carbon (C) and nitrogen (N). However, fractionation of carbon during lipid synthesis violates this assumption; high-lipid tissues do not reflect δ(13) C values of diet and therefore have the potential to skew mixing model results and diet interpretations, making corrections necessary. METHODS: Brook Trout (Salvelinus fontinalis) white muscle and liver samples from several fish species representing the temperate North American cold- and warm-water fish community were corrected for lipids via chemical lipid extraction and mathematical lipid normalization. To assess the accuracy of model-predicted lipid-free δ(13) C values calculated from four normalization models, we compared model-predicted values with those measured after lipid extraction. RESULTS: We found that chemical lipid extraction is unnecessary for Brook Trout white muscle tissue with low initial lipid content. However, in tissues with C:N ratios greater than 3.5, lipid extraction increased δ(13) C values in fish liver by more than 1.0 ‰, indicating that liver lipid content is sufficient to bias δ(13) C values. We also found that lipids were accurately accounted for with mathematical normalization and recommend that tissues with C:N ratios greater than 3.5 be corrected mathematically. CONCLUSIONS: Our findings indicate that mathematical normalization is sufficient to account for bias in δ(13) C values associated with lipid content in fish tissues when C:N ratios are above 3.5. C:N ratios below 3.5 indicate that tissues have insufficient levels of lipid to bias the δ(13) C values. Generally, these findings support the use of more timely and cost-effective processing and analysis methods in future aquatic food-web studies utilizing SIA. Copyright © 2016 John Wiley & Sons, Ltd.

Assessment of the Readability of Genetic Counseling Patient Letters.

Patient letters are a powerful tool that genetic counselors use to communicate with their patients. Patient letters are often sent to provide information on a new diagnosis, reiterate test results, and to serve as a permanent record of the visit. Patient letters, however, are only helpful if the patients can understand them. More than 50 % of the US population reads below a 9th grade reading level and over one-third of the population has low health literacy skills. In this study we evaluate the readability of genetic counseling patient letters by assessing reading level, image use, and terminology use. One hundred forty-nine genetic counselors participated in the survey and of these, 79 submitted a sample patient letter. Analyses of the letters revealed a mean reading level of 10.93. On average, 6 genetic terms were included in each letter, and only 25 % of these terms were defined. Analyses of survey responses revealed over 75 % of the genetic counselors did not include images in their patient letters. These results indicate there is room for improvement in order to make genetic counseling patient letters more accessible to the general population.

Wetland phosphorus dynamics and phosphorus removal potential.

Wetlands are typically defined as inundated areas with hydric soils forming a transitional zone between terrestrial and aquatic systems. Wetlands have numerous ecosystem benefits, one of which is the potential to mitigate or reverse eutrophication of surface water bodies. The physical, chemical, and biological processes governing phosphorus cycling in wetlands are nuanced and complex; understanding these has direct relevance to the restoration of wetlands, particularly for projects aimed at improving water quality in adjacent water bodies. This literature review summarizes these processes and provides recommendations relevant to restoration of permanent and semipermanent flow-through wetlands, such as those in the Upper Klamath Basin of Oregon. It also reviews several wetland restoration studies assessing phosphorus removal. In summary, appropriately designed and managed wetlands can remove 25% to 44% of inflowing total phosphorus. Deposition of particulate matter, adsorption, uptake by biomass, and peat accretion are the primary phosphorus sequestration mechanisms in wetlands, depending on site-specific conditions (e.g., growing season length, vegetation communities, and soil type). In areas with relatively short growing seasons and where wintertime loads are targeted for treatment, as in the Upper Klamath Basin, deposition of particulate matter will be the primary mechanism for phosphorus sequestration in wetlands given that two of the three remaining processes occur during the growing season. Recommendations to maximize phosphorus sequestration in wetlands include the following: designing wetlands for hydraulic residence time of several days to weeks, managing wetlands for rapid establishment of wetland vegetation with limited decomposition potential (e.g., tule [hardstem bulrush] to facilitate peat accretion), and flooding during periods with low water temperatures and initially isolating restored wetlands from adjacent water bodies (both to minimize diffusive flux of phosphorus from wetland sediment to the water column). Relevant to the Upper Klamath Basin, there is also justification to prioritize areas with relatively high particulate phosphorus load given the potential limited capacity for phosphorus treatment associated with other sequestration mechanisms. Finally, a combination of mitigation and restoration strategies is necessary to achieve water quality objectives, meaning that wetland restoration alone may not be sufficient. Monitoring is advised to facilitate application of adaptive management principles. PRACTITIONER POINTS: Appropriately designed and managed wetlands can remove 25% to 44% of inflowing total phosphorus. Deposition of particulate matter, adsorption, uptake by biomass, and peat accretion are the primary phosphorus sequestration mechanisms in wetlands, depending on site-specific conditions (e.g., growing season length, vegetation communities, and soil type). Recommendations to maximize phosphorus sequestration in wetlands include designing wetlands for hydraulic residence time of several days to weeks; managing wetlands for rapid establishment of wetland vegetation with limited decomposition potential (e.g., tule [hardstem bulrush], to facilitate peat accretion); and flooding during periods with low water temperatures and initially isolating restored wetlands from adjacent water bodies (both to minimize diffusive flux of phosphorus from wetland sediment to the water column). A combination of mitigation and restoration strategies are necessary to achieve water quality objectives, meaning that wetland restoration alone may not be sufficient. Monitoring is advised to facilitate application of adaptive management principles.

Dietary and total calcium intakes are associated with lower percentage total body and truncal fat in young, healthy adults.

OBJECTIVE: To investigate the relationship between different sources of calcium intake (dairy [milk products only], dietary [all dietary sources including dairy], nondairy dietary [all dietary sources excluding dairy], and total [dietary + supplemental]) and fat mass in young adults. METHODS: One hundred ninety-seven healthy Caucasian men and women aged 18 to 28 years from southwestern Ontario underwent whole-body dual-energy x-ray absorptiometry to determine total body fat mass (%FM) and truncal fat (%TF). Calcium intakes, determined using a food frequency questionnaire, were divided into quartiles for each of dairy, dietary, nondairy dietary, and total sources. Physical activity scores were collected on a subset of subjects (n = 167). Mean %FM and %TF were compared between the lowest (Q1) and highest (Q4) quartiles of calcium consumers for each calcium source. Calcium intakes between subjects with %FM ≥ 50th and <50th percentile were also compared. RESULTS: Mean calcium intakes were as follows: 568 mg/d dairy calcium, 312 mg/d nondairy dietary calcium, 881 mg/d dietary calcium, 68 mg/d supplemental calcium, and 948 mg/d total calcium. %FM was 3.9%-4.9% lower and %TF was 4.1%-5.0% lower (all P ≤ 0.05) for subjects in Q4 vs Q1, regardless of calcium source (dairy, dietary, and total). When adjusted for physical activity, lower %FM and %TF persisted (P ≤ 0.05) for subjects in Q4 (1113-1595 mg/d mean dietary and total calcium intakes) vs Q1 (116-393 mg/d mean dietary and total calcium intakes). Calcium intakes from dairy, dietary, and total sources for subjects with a %FM ≥ 50th percentile were significantly lower (all P ≤ 0.05); when adjusted for physical activity, dietary (P = 0.025) and total (P = 0.060) calcium intakes remained lower. IMPLICATIONS AND CONCLUSIONS: Our findings support a relationship, even after adjusting for physical activity, between higher dietary and total calcium intakes and lower total body and truncal fat in young adults. Results suggest an intake of approximately 1500 mg/d calcium could aid in the management of body and truncal fat. We recommend that young adults be encouraged to increase their total calcium intakes to at least the recommended daily allowance of 1000 mg/d for reasons extending beyond bone health.

Analysis of pmpD expression and PmpD post-translational processing during the life cycle of Chlamydia trachomatis serovars A, D, and L2.

BACKGROUND: The polymorphic membrane protein D (PmpD) in Chlamydia is structurally similar to autotransporter proteins described in other bacteria and may be involved in cellular and humoral protective immunity against Chlamydia. The mechanism of PmpD post-translational processing and the role of its protein products in the pathogenesis of chlamydial infection have not been very well elucidated to date. METHODOLOGY/PRINCIPAL FINDINGS: Here we examined the expression and post-translational processing of the protein product of the pmpD gene during the life cycle of C. trachomatis serovars A, D, and L2. Each of these three serovars targets different human organs and tissues and encodes a different pmpD gene nucleotide sequence. Our quantitative real-time reverse transcription polymerase chain reaction results demonstrate that the pmpD gene is up-regulated at 12-24 hours after infection regardless of the Chlamydia serovar. This up-regulation is coincidental with the period of exponential growth and replication of reticulate bodies (RB) of Chlamydia and indicates a probable similarity in function of pmpD in serovars A, D, and L2 of Chlamydia. Using mass spectrometry analysis, we identified the protein products of post-translational processing of PmpD of C. trachomatis serovar L2 and propose a double pathway model for PmpD processing, with one cleavage site between the passenger and autotransporter domains and the other site in the middle of the passenger domain. Notably, when Chlamydia infected culture cells were subjected to low (28 degrees C) temperature, PmpD post-translational processing and secretion was found to be uninhibited in the resulting persistent infection. In addition, confocal microscopy of cells infected with Chlamydia confirms our earlier hypothesis that PmpD is secreted outside Chlamydia and its secretion increases with growth of the chlamydial inclusion. CONCLUSION/SIGNIFICANCE: The results of this current study involving multiple Chlamydia serovars support the general consensus that the pmpD gene is maximally expressed at mid infection and provide new information about PmpD as an autotransporter protein which is post-translationally processed and secreted outside Chlamydia during normal and low temperature induced persistent chlamydial infection.