The Effects of Intraspecific Variation of Crayfish Behavior on Nutrient Cycling in Aquatic Environments

Human activities are rapidly altering species traits at a global scale. Yet, there remains a critical need to determine whether trait variation within species affects ecosystem responses to global change. In particular, intraspecific variation in feeding behavior can have strong effects on ecosystem processes, such as nutrient cycling in streams. Crayfish are dominant consumers in streams and play key roles in controlling important stream dynamics such as nutrient cycling. We hypothesized that within-population, individual variation in crayfish foraging behavior is associated with differences in nutrient excretion. The objectives of this study were to (i) to quantify individual differences in foraging behavior and boldness of crayfish using a giving up density (GUD) approach. (ii) to quantify individual differences in nutrient excretion of crayfish. (iii) to test whether foraging rate, boldness, and excretion rate are repeatable traits in the laboratory setting and (iv) to examine whether there is a relationship between individual variation in foraging rate, boldness, and excretion. These objectives were explored with both behavioral and excretion assays, and general linear and nonlinear mixed models as well as ANOVA tests. We found that behavior and excretion were repeatable and that behavior is associated with ammonium excretion. The finding that crayfish foraging behavior is associated with differences in nutrient excretion has important implications for invasion ecology and nutrient cycling. It is known that behavioral changes occur along with invasion. These behavioral changes can significantly impact the nutrient excretion, and therefore nutrient dynamics within invaded environments.No embargoAcademic Major: Environmental Scienc

The effect of enzymatic hydrolysis of a dietary protein on the excretion of urinary nitrogen metabolites : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Nutritional Science at Massey University, Palmerston North, New Zealand

Floppy disc in back pocket - not copied/unreadableHydrolysed milk proteins are used for many purposes in human nutrition. Although it is assumed that the nutritive value of a protein hydrolysate is the same, or even superior to the corresponding intact protein, there is limited research available to support this assumption. The aim of this study was to compare amino acid utilisation and the pattern of excretion in the urine of the nitrogenous metabolites (urea, ammonia and creatinine) as an immediate response to the ingestion of a meal containing an intact protein or its enzymatic hydrolysate. This involved a novel technique, 'acute urine collection' (AUC), in which urine was drained from the bladder at short time periods (30 min to 2 hr) through a catheter. The performance and nitrogen balance results indicated that the two sources of amino acid were equally effective in supporting nitrogen retention and growth of the pigs. Nevertheless, the pattern of excretion of the metabolites of nitrogen digestion suggested important differences in the metabolism of the pigs on the two diets. Both groups of pig excreted creatinine nitrogen, at constant and comparable rates over the sampling period indicating similar rates of catabolism in the muscle. The total excretion of nitrogen by AUC by the two groups was similar but the pattern of excretion over the day differed which indicated a difference in the metabolism of the amino acids in the diets. This may have been in part due to a more rapid absorption of amino acids from the hydrolysed diet and in part due to a higher rate of glutamine and asparagine breakdown in the gut of pigs fed the hydrolysate. Excretion of nitrogen as urea and ammonia was similar for the two groups but there were differences between the groups in the pattern of excretion of these metabolites. In addition, the excretion of ammonia was significantly lower (P <0.0001) in the pigs fed the hydrolysate. This was due to a higher content of fixed cations in the diet containing the hydrolysate that led to a compensatory reduction in ammonia excretion. There was a proportional increase in the excretion of urea in the pigs on the hydrolysed diet as a result of the reduction in ammonia excretion but the differences were small relative to the total urea excretion and not significant. AUC not only gives comparable information to the nitrogen balance if it is carried out over a 24 hr period but it also provides detailed information about the protein utilisation during the immediate postprandial period. In particular, AUC can indicate differences and/or similarities in protein absorption by allowing the observation of the pattern of production of urea directly related to the catabolism of dietary amino acids. In addition, it may be possible to use this technique to estimate the optimum time between meals

Urinary porphyrin excretion in hepatitis C infection

A high prevalence of hepatitis C virus infection in porphyria cutanea tarda in some populations suggests a close link between viral hepatitis and alteration of porphyrin metabolism. Moreover, there is evidence of a role of porphyrinopathies in hepatocarcinogenesis. The aim of our study was to obtain data on the prevalence and patterns of heme metabolism alterations in patients with chronic hepatitis C virus infection. Urinary porphyrin excretion was prospectively studied in 100 consecutive outpatients with chronic hepatitis C infection without signs of photosensitivity, using an ion-pair high performance liquid chromatography method. Increased total porphyrin excretion was found in 41 patients, with predominant excretion of coproporphyrins (whole study group: mean 146 mu g/g creatinine, interquartile range 76-186; normal &lt;150), in 10 patients excretion exceeded 300 mu g/g creatinine. In the majority of all patients studied (75/100) an increased ratio of the relatively hydrophobic coproporphyrin isomer I to isomer III was found. In just one case, urinary porphyrin pattern characteristic for chronic hepatic porphyria was present (uroporphyrin &gt; coproporphyrin, heptacarboxyporphyrin III increased) but the total porphyrin excretion was only slightly elevated in this case. In the whole group, total urinary porphyrin excretion correlated well with serum bilirubin and was inversely correlated with albumin and thrombin time. In conclusion, secondary coproporphyrinuria occurs frequently in heptatitis C infection, whereas in Germany, preclinical porphyria cutanea tarda seems to be rare in these patients

Lithium treatment reduces the renal kallikrein excretion rate

Lithium treatment reduces the renal kallikrein excretion rate. Lithium salts are widely used agents for the prophylactic treatment of affective disorders. Lithium salts may be associated with distal nephron dysfunction. Kallikrein is a protease which is generated by the distal nephron. We used an amidolytic assay of chromatographically purified enzyme to determine the urinary excretion rate of active kallikrein in relation to lithium treatment. All plasma lithium concentrations were within the therapeutic range (0.4 to 0.9 mmol/liter). In 15 patients the urinary excretion rate of active kallikrein was 267.4 65.6 mU/24 hrs before lithium treatment, and fell to 117.8 39.6 mU/24 hrs (P < 0.05) on day 14 of lithium treatment. This reduction was associated with a decrease of immunoreactive kallikrein in the same urines by 66%. In another 15 patients who had undergone lithium therapy for an average period of 5.6 years, the urinary excretion rate of active kallikrein was 86.1 14.5 mU/24 hrs, while 21 age-matched healthy controls had an excretion rate of 364.1 58.4 mU/24 hrs (P < 0.05). Measurements of immunoreactive kallikrein in the same urine samples demonstrated a reduction of kallikrein after long-term lithium treatment by 78%. These observations could not be attributed to changes in creatinine clearance, renal sodium or potassium excretion rates or plasma concentrations of aldosterone and vasopressin. Addition of lithium to the urine in vitro had no demonstrable effect on kallikrein measurement by amidolytic assay. We conclude that lithium in therapeutic plasma concentrations may directly suppress the secretion of kallikrein by renal connecting tubule cells

Sugar intake among German adolescents: trends from 1990-2016 based on biomarker excretion in 24-h urine samples

Trend analyses based on dietary records suggest decreases in the intakes of total (TS), added (AS) and free sugar (FS) since 2005 among children and adolescents in Germany. In terms of age trends, TS intake decreased with increasing age. However, self-reported sugar intake in epidemiological studies is criticized, as it may be prone to bias due to selective underreporting. Furthermore, adolescents are more susceptible to underreporting than children. We thus analyzed time and age trends in urinary fructose excretion (FE), sucrose excretion (SE) and the sum of both (FE+SE) as biomarkers for sugar intake among 8.5-16.5-year-old adolescents. Urinary sugar excretion was measured by UPLC-MS/MS in 997 24-h urine samples collected from 239 boys and 253 girls participating in the DONALD study cohort between 1990 and 2016. Time and age trends of log-transformed FE, SE and FE+SE were analyzed using polynomial mixed-effects regression models. Between 1990 and 2016 FE as well as FE+SE decreased (linear time trend: p=0.0272 and p<0.0001, respectively). A minor increase in excretion during adolescence was confined to FE (linear age trend: p=0.0017). The present 24-h excretion measurements support a previously reported dietary-record based decline in sugar intake since 2005. However, the previous seen dietary record-based decrease in TS from childhood to late adolescence was not confirmed by our biomarker analysis, suggesting a constant sugar intake for the period of adolescence

Algal culture studies related to a Closed Ecological Life Support System (CELSS)

Studies with algal cultures which relate to closed ecological life support systems (CELSS) are discussed. A description of a constant cell density apparatus for continuous culture of algae is included. Excretion of algal by-products, and nitrogen utilization and excretion are discussed

Experimental investigation of the role of thyrocalcitonin in the prophylaxis of disturbances in the water-salt and mineral metabolism during a 30-day hypokinesia

The effect of thyrocalcitonin (TCT) injections on the metabolism of water and electrolytes in free-moving and immobilized chinchilla hares is described. Calcium excretion from immobilized animals was elevated, but normalized in those also receiving TCT injections. TCT also normalized water content and excretion rates

Pilot trial of fk 506 in the management of steroid-resistant nephrotic syndrome

Seven patients with steroid-resistant nephrotic syndrome were treated with FK 506 monotherapy. Four patients were children with focal sclerosing glomerulonephritis (FSGS). Three of these had evldence for chronic progressive renal disease consisting of interstitial fibrosis and tubular atrophy on pretreatment renal biopsies. Two patients had also failed cyclosporin A (CsA), two cyclophosphamide, and one chlorambucil prior to treatment with FK 506. Three patients were adults wlth mesangial proliferative. membranoproliferative, and membranous glomerulonephritis. Three patterns of response were noted: (1) a reduction in proteinuria to normal levels, (2) partial response (50% reduction) or; (3) no improvement. All patients except one experienced at least a 50% reduction in protein excretion at some time during FK 506 therapy. Two of the children and one adult reduced protein excretion to essentially normal values. One patient had no sustained reduction In Droteln excretion and is considered to be a treatment fallure, although her protein excretion was approximately 50% of pretreatment values intermittently. The drug was generally well tolerated. The most common side-effect was nephrotoxlclty, whlch was reversible. These encouraging results suggest that FK 506 monotherapy may be effective in controlling the proteinuria of somc patlents with steroid-resistant nephrotic syndrome The use of this drug may extend our understanding of the role of T lymphocytes and cytokines in the pathogenesls of glomerulonephritis. Further study of this agent In a larger population of patlents is warranted. © 1993 European Dialysis and Transplant Assoiation-European Renal Association

The Influence of Dissolved Organic Matter (DOM) on Sodium Regulation and Nitrogenous Waste Excretion in the Zebrafish (Danio rerio)

Dissolved organic matter (DOM) is both ubiquitous and diverse in composition in natural waters, but its effects on the branchial physiology of aquatic organisms have received little attention relative to other variables (e.g. pH, hardness, salinity, alkalinity). Here, we investigated the effects of four chemically distinct DOM isolates (three natural, one commercial, ranging from autochthonous to highly allochthonous, all at ∼6 mg C l−1) on the physiology of gill ionoregulation and nitrogenous waste excretion in zebrafish acclimated to either circumneutral (7.0–8.0) or acidic pH (5.0). Overall, lower pH tended to increase net branchial ammonia excretion, net K+ loss and [3H]PEG-4000 clearance rates (indicators of transcellular and paracellular permeability, respectively). However, unidirectional Na+ efflux, urea excretion and drinking rates were unaffected. DOM sources tended to stimulate unidirectional Na+ influx rate and exerted subtle effects on the concentration-dependent kinetics of Na+ uptake, increasing maximum transport capacity. All DOM sources reduced passive Na+ efflux rates regardless of pH, but exerted negligible effects on nitrogenous waste excretion, drinking rate, net K+ loss or [3H]PEG4000 clearance, so the mechanism of Na+ loss reduction remains unclear. Overall, these actions appear beneficial to ionoregulatory homeostasis in zebrafish, and some may be related to physicochemical properties of the DOM sources. They are very different from those seen in a recent parallel study on Daphnia magna using the same DOM isolates, indicating that DOM actions may be both species and DOM specific

Methodological considerations in the analysis of fecal glucocorticoid metabolites in tufted capuchins (Cebus apella)

Analysis of fecal glucocorticoid (GC) metabolites has recently become the standard method to monitor adrenocortical activity in primates noninvasively. However, given variation in the production, metabolism, and excretion of GCs across species and even between sexes, there are no standard methods that are universally applicable. In particular, it is important to validate assays intended to measure GC production, test extraction and storage procedures, and consider the time course of GC metabolite excretion relative to the production and circulation of the native hormones. This study examines these four methodological aspects of fecal GC metabolite analysis in tufted capuchins (Cebus apella). Specifically, we conducted an adrenocorticotrophic hormone (ACTH) challenge on one male and one female capuchin to test the validity of four GC enzyme immunoassays (EIAs) and document the time course characterizing GC me- tabolite excretion in this species. In addition, we compare a common field-friendly technique for extracting fecal GC metabolites to an established laboratory extraction methodology and test for effects of storing “field extracts” for up to 1 yr. Results suggest that a corticosterone EIA is most sensitive to changes in GC production, provides reliable measures when extracted according to the field method, and measures GC metabolites which remain highly stable after even 12 mo of storage. Further, the time course of GC metabolite excretion is shorter than that described yet for any primate taxa. These results provide guidelines for studies of GCs in tufted capuchins, and underscore the importance of validating methods for fecal hormone analysis for each species of interest