10 research outputs found

    Studies on the extent of ruminal degradation of phytate from different feedstuffs

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    The predominant storage form of phosphorus (P) in plant seeds and grains is phytate (InsP6). To cleave the phosphate group and, thus, make the bound P available for absorption by the animal, the enzyme phytase is required. Rumen microorganisms show substantial phytase activity, however, recent studies have suggested that the extent of InsP6 hydrolysis in ruminants is variable leading to an incomplete hydrolysis of InsP6 in specific conditions followed by the excretion of P from undegraded InsP6. As P is an essential element for the metabolism in animals it is important to ensure that the animals requirements are met. Diets for ruminants are often supplemented with mineral P (Pi). However, the global phosphate resources are finite and the excretion of surplus P contributes to eutrophication of surface water when applied to the farmland with manure in excessive amounts. Thus, dietary P supply is of environmental concern. Better knowledge about ruminal InsP6 hydrolysis could help to optimise the utilisation of InsP6 and, thus, reduce the use of Pi as well as unnecessary excretion of P. Hence, the objectives of the present thesis were to examine the InsP6 hydrolysis from different feedstuffs in ruminants and to identify factors that might affect the extent of InsP6 hydrolysis. In the first study, the total digestive tract disappearance of InsP6 from diets differing in amount and source of P was determined in lactating dairy cows. The results confirmed the high potential of rumen microorganisms to hydrolyse InsP6, but the composition of the diet influenced the extent of hydrolysis in vivo. In the second study, two in vitro experiments were conducted in order to determine the InsP6 hydrolysis from maize grain and RSM. In experiment 1, two diets differing in P- and InsP6-P concentration were fed to the donor animals of rumen fluid. In experiment 2, a diet similar to the high P diet of experiment 1 was fed to the donor animals of rumen fluid and the rumen fluid was mixed with artificial saliva containing Pi (PI: 120 mg Pi/l) or no Pi. Maize and RSM were incubated for 3, 6, 12, and 24 h in both experiments and the InsP6 concentration was analysed in fermenter fluids and bag residues. InsP6 disappearance from maize proceeded faster than from RSM. The disappearance of InsP6 was higher when the diet with high P concentration was fed (experiment 1) and lower when the rumen fluid was mixed with Pi containing buffer (experiment 2). In the third study, the in situ disappearance of InsP6 from five different concentrates was examined. Maize, wheat, RSM, heat treated RSM (hRSM), and soybean meal were incubated in the rumen of fistulated dairy cows fed with three diets differing in P- and InsP6-P concentration. Concentrations of InsP6 and isomers of InsP5, InsP4, and InsP3 were determined in the bag residues after 2, 4, 8, 16, and 24 h of incubation. The disappearance of InsP6 from cereals proceeded faster than from oilseed meals, however, averaged over the diets, after 24 h of incubation 95% had disappeared from all concentrates except for hRSM (57%). Feeding the diet with high InsP6 concentrations increased InsP6 disappearance from oilseed meals but not from cereals, while feeding the high Pi diet did not influence ruminal InsP6 hydrolysis from any concentrate. The results derived from analysis of lower InsPs suggested that intrinsic plant phytase activity plays only a minor role in the rumen and that active phytases in the rumen react differently to changes in the ruminal environment. The results of the present thesis suggest that the composition of the diet fed to ruminants affects the extent of ruminal InsP6 hydrolysis. While high InsP6 concentrations have the potential to increase InsP6 hydrolysis, a decrease of InsP6 hydrolysis can occur after addition of Pi to the diet. Differences in the pace of InsP6 hydrolysis between concentrates occurred which could be of importance at high ruminal passage rates when the time available for ruminal hydrolysis decreases.Phosphor (P) wird in pflanzlichen Samen und Körnern überwiegend als Phytat (InsP6) gespeichert. Um die Phosphatgruppe abzuspalten und so den darin gebundenen P für die Absorption verfügbar zu machen, wird das Enzym Phytase benötigt. Ruminale Mikroorganismen weisen eine nicht unerhebliche Phytaseaktivität auf, Studien der letzten Jahre zeigten allerdings, dass auch beim Wiederkäuer die InsP6-Hydrolyse beeinträchtigt werden kann und entsprechend P aus nicht abgebautem InsP6 ausgeschieden wird. Genauere Erkenntnisse zur ruminalen InsP6-Hydrolyse können dazu beitragen, die Verwertung von InsP6 zu optimieren. Ziel dieser Arbeit war es daher, die Hydrolyse von InsP6 aus unterschiedlichen Futtermitteln beim Wiederkäuer näher zu untersuchen und Faktoren zu identifizieren, die die InsP6-Hydrolyse beeinflussen können. Im Rahmen der ersten Studie wurde der InsP6-Abbau aus verschiedenen Rationen im Gesamtverdauungstrakt laktierender Milchkühe bestimmt. Die Rationen unterschieden sich hinsichtlich der P-Konzentration und P-Quelle. Die Ergebnisse bestätigen das hohe Potential der Mikroorganismen im Pansen zur InsP6-Hydrolyse, die Zusammensetzung der Ration beeinflusste allerdings das Ausmaß des Abbaus in vivo. Für die zweite Studie wurden zur Bestimmung der InsP6-Hydrolyse aus Mais und RSM zwei in vitro Experimente durchgeführt. In Experiment 1 wurden die Spendertiere des Pansensaftes mit zwei Rationen angefüttert, die sich hinsichtlich der P- und InsP6-Konzentration unterschieden. In Experiment 2 wurden die Tiere mit einer Ration angefüttert, die mit der P-reichen Ration aus Experiment 1 vergleichbar war und der Pansensaft mit P-haltigem (120 mg P/l) oder P-freiem Puffer gemischt. Mais und RSM wurden jeweils für 3, 6, 12 und 24 h inkubiert und anschließend die InsP6-Konzentration in der Fermenterflüssigkeit und im Futterrückstand bestimmt. Die InsP6-Hydrolyse verlief bei Mais schneller als bei RSM und war bei Fütterung der P-reichen Ration höher als bei Fütterung der P-armen Ration, die Zulage von mineralischem P über den Puffer führte zu einem Rückgang der Hydrolyse. In der dritten Studie wurde der ruminale Abbau von InsP6 aus fünf verschiedenen Futtermitteln untersucht. Die Inkubation von Mais, Weizen, RSM, hitzebehandeltem RSM und Sojaextraktionsschrot erfolgte bei Fütterung dreier unterschiedlicher Rationen. Die InsP6-Konzentration sowie die Konzentrationen der Isomere von InsP5, InsP4 und InsP3 wurden in den Beutelrückständen nach 2, 4, 8, 16 und 24 h gemessen. Der InsP6-Abbau verlief bei Getreide schneller als bei den Ölschroten, nach 24 h Inkubation war jedoch bei allen Futtermitteln 95% des InsP6 aus den Beuteln verschwunden. Einzig bei Inkubation von hRSM waren nach 24 h lediglich 57% des InsP6 abgebaut. Bei Fütterung der InsP6-reichen Ration stieg der InsP6-Abbau bei den Ölschroten an. Dieser Effekt war bei den Getreiden nicht nachzuweisen. Die Fütterung einer Ration mit Zulage von mineralischem P zeigte dagegen bei keinem der untersuchten Futtermittel einen Einfluss auf den ruminalen in situ Abbau von InsP6. Die Konzentrationen der Isomere der niederen InsPs in den Inkubationsrückständen ließen vermuten, dass die endogene pflanzliche Phytaseaktivität im Pansen eine untergeordnete Rolle spielt. Zudem scheinen die im Pansen aktiven Phytasen auf Rationsänderungen unterschiedlich zu reagieren. Die Ergebnisse der vorliegenden Arbeit legen den Schluss nahe, dass die Zusammensetzung der an Wiederkäuer verfütterten Rationen das Ausmaß der ruminalen InsP6-Hydrolyse beeinflussen kann. Hohe InsP6-Konzentrationen in der Ration scheinen den Abbau von InsP6 zu steigern während eine Zulage von mineralischem P einen negativen Einfluss haben kann. Des Weiteren waren Unterschiede hinsichtlich der Geschwindigkeit, in der der InsP6-Abbau voranschritt, zwischen den untersuchten Futtermitteln zu erkennen. Dies könnte vor allem bei hohen Passageraten für das Ausmaß des ruminalen InsP6-Abbaus von Bedeutung sein, wenn weniger Zeit zur Hydrolyse zur Verfügung steht

    Characterization of SNF472 pharmacokinetics and efficacy in uremic and non-uremic rats models of cardiovascular calcification

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    End-stage renal disease is strongly associated with progressive cardiovascular calcification (CVC) and there is currently no therapy targeted to treat CVC. SNF472 is an experimental formulation under development for treatment of soft tissue calcification. We have investigated the pharmacokinetics of SNF472 administration in rats and its inhibitory effects on CVC. SNF472 was studied in three rat models: (1) prevention of vitamin D3-induced CVC with an intravenous SNF472 bolus of 1 mg/kg SNF472, (2) inhibition of progression of vitamin D3-induced CVC with a subcutaneous SNF472 bolus of 10 or 60 mg/kg SNF472, starting after calcification induction, (3) CVC in adenine-induced uremic rats treated with 50 mg/kg SNF472 via i.v. 4h -infusion. Uremic rats presented lower plasma levels of SNF472 than control animals after i.v. infusion. CVC in non-uremic rats was inhibited by 60-70% after treatment with SNF472 and progression of cardiac calcification completely blocked. Development of CVC in uremic rats was inhibited by up to 80% following i.v. infusion of SNF472. SNF472 inhibits the development and progression of CVC in uremic and non-uremic rats in the same range of SNF472 plasma levels but using in each case the required dose to obtain those levels. These results collectively support the development of SNF472 as a novel therapeutic option for treatment of CVC in humans

    The present and future of prostate cancer urine biomarkers

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    In order to successfully cure patients with prostate cancer (PCa), it is important to detect the disease at an early stage. The existing clinical biomarkers for PCa are not ideal, since they cannot specifically differentiate between those patients who should be treated immediately and those who should avoid over-treatment. Current screening techniques lack specificity, and a decisive diagnosis of PCa is based on prostate biopsy. Although PCa screening is widely utilized nowadays, two thirds of the biopsies performed are still unnecessary. Thus the discovery of non-invasive PCa biomarkers remains urgent. In recent years, the utilization of urine has emerged as an attractive option for the non-invasive detection of PCa. Moreover, a great improvement in high-throughput "omic" techniques has presented considerable opportunities for the identification of new biomarkers. Herein, we will review the most significant urine biomarkers described in recent years, as well as some future prospects in that field

    Deciphering the cryptic genome: Genome-wide analyses of the rice pathogen <em>Fusarium fujikuroi</em> reveal complex regulation of secondary metabolism and novel metabolites.

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    The fungus Fusarium fujikuroi causes &ldquo;bakanae&rdquo; disease of rice due to its ability to produce gibberellins (GAs), but it is also known for producing harmful mycotoxins. However, the genetic capacity for the whole arsenal of natural compounds and their role in the fungus&#39; interaction with rice remained unknown. Here, we present a high-quality genome sequence of F. fujikuroi that was assembled into 12 scaffolds corresponding to the 12 chromosomes described for the fungus. We used the genome sequence along with ChIP-seq, transcriptome, proteome, and HPLC-FTMS-based metabolome analyses to identify the potential secondary metabolite biosynthetic gene clusters and to examine their regulation in response to nitrogen availability and plant signals. The results indicate that expression of most but not all gene clusters correlate with proteome and ChIP-seq data. Comparison of the F. fujikuroi genome to those of six other fusaria revealed that only a small number of gene clusters are conserved among these species, thus providing new insights into the divergence of secondary metabolism in the genus Fusarium. Noteworthy, GA biosynthetic genes are present in some related species, but GA biosynthesis is limited to F. fujikuroi, suggesting that this provides a selective advantage during infection of the preferred host plant rice. Among the genome sequences analyzed, one cluster that includes a polyketide synthase gene (PKS19) and another that includes a non-ribosomal peptide synthetase gene (NRPS31) are unique to F. fujikuroi. The metabolites derived from these clusters were identified by HPLC-FTMS-based analyses of engineered F. fujikuroi strains overexpressing cluster genes. In planta expression studies suggest a specific role for the PKS19-derived product during rice infection. Thus, our results indicate that combined comparative genomics and genome-wide experimental analyses identified novel genes and secondary metabolites that contribute to the evolutionary success of F. fujikuroi as a rice pathogen
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