Status-quo-Analyse: Datenauswertung zur Fütterungssituation und zum Leistungsgeschehen von Milchkühen im ökologischen Landbau - Weiterentwicklung von Fütterungsempfehlungen

In der vorliegenden Arbeit wurden Daten aus ökologischen Milchviehbetrieben des Rheinlandes und aus Westfalen ausgewertet, um Milchleistungen in diesen Betrieben der jeweiligen Fütterungssituation zuordnen zu können. Als Datengrundlage dienten hierfür zum einen die Ergebnisse der Milchleistungsprüfung über den Zeitraum von Januar 2003 bis März 2006 und zum anderen die Sammelmilchproben der Betriebe aus jeder Milchabholung durch die Molkerei. Die Zahl der Betriebe, zu denen Milchdaten verfügbar waren, betrug 68. Als Basis der Daten zur Fütterungssituationen dienten Aufzeichnungen der Landwirtschaftskammer Nordrhein-Westfalen in Münster. Diese Aufzeichnungen enthielten Angaben über den Weideanteil im Sommer, die Einsatzmengen an Kraftfutter pro Kuh und Jahr und die anteiligen Mengen verschiedener Pflanzen an der Hauptfutterfläche. Diese Angaben waren von 49 Betrieben verfügbar, bezogen sich jedoch immer auf die gesamte Herde und den Jahresdurchschnitt, so dass genaue Zuordnungen von konkreten Rationen zu den dazugehörenden Milchleistungen oder Milchinhaltsstoffen nicht möglich waren. Es wurde versucht, durch die Auswahl von Betrieben mit besonders hohen beziehungsweise niedrigen Leistungen oder Inhaltsstoffen, Unterschiede bezüglich der eingesetzten Futtermittel oder des Weideanteiles im Sommer darzustellen. Weiterhin wurden Betriebe ausgewählt, die im Vergleich zum Mittel aller Betriebe extreme Futtergrundlagen einsetzten. Diese Fütterungsschwerpunkte wurden dann mit den erzielten Milchleistungen in Verbindung gebracht und ausgewertet

Odorant-Bindeproteine (OBPs) als molekulare Detektoreinheiten für die Erkennung und Diskriminierung von Duftstoffen

Das olfakorische System ist in der Lage, Tausende von Duftstoffen zu diskriminieren und sie z.T. in geringste Konzentrationen zu detektieren. Diese enorme Erkennungskapazität wird generell auf die Vielfalt an Odorantrezeptoren der olfaktorischen Sinneszellen zurückgeführt. Man geht jedoch davon aus, daß die Duftstoffmoleküle zunächst mit den sogenannten Odorant-Bindeproteinen (OBPs) interagieren, die als Transporter die überwiegend hydrophoben organischen Moleküle durch die wässrige Mucusbarriere zu den Sinneszellen transferieren. OBPs gehören zu den Lipocalinen, die sich durch eine simple aber sehr rigide beta-Faß Struktur mit einer hydrophoben Bindungstasche und einer überwiegend hydrophilen Proteinoberfläche auszeichnen; sie stellen damit ideale „Lösungsvermittler“ für hydrophobe Substanzen dar. Die Entdeckung von mehreren OBP-Subtypen in einer Spezies und die geringe Sequenzhomologie der Subtypen untereinander legte die Vermutung nahe, dass die unterschiedlichen OBPs für die Interaktion mit distinkten chemischen Strukturklassen spezialisiert sind, d.h. über eine gewissen Ligandenspezifität verfügen. Im Hinblick auf detaillierte Analysen der Bindungseigenschaften von OBPs wurden drei identifizierte OBP-Subtypen der Ratte in E. coli als Histidin-Fusionsproteine überexprimiert und unter nativen Bedingungen gereinigt. Für die Charakterisierung der Wechselwirkungen dieser Proteine mit verschiedenen Liganden wurde ein markierungsfreier fluoreszenzspektroskopischer “Schnelltest“ entwickelt, der auf einer reversiblen Interaktion von OBP mit Fluoreszenzchromophor beruht. Durch die Änderung der Fluoreszenzeigenschaften des Chromophors bei einer spezifischen Wechselwirkung mit dem OBP sind die gebundenen Chromophoren im Emissionsspektrum selektiv erkennbar; eine Trennung von freiem und gebundenen Chromophore wird dadurch überflüssig. Diese Methode scheint für ein Hochdurchsatzscreening prädestiniert zu sein

Mammalian Olfactory Receptors

Perception of chemical stimuli from the environment is essential to most animals; accordingly, they are equipped with a complex olfactory system capable of receiving a nearly unlimited number of odorous substances and pheromones. This enormous task is accomplished by olfactory sensory neurons (OSNs) arranged in several chemosensory compartments in the nose. The sensitive and selective responsiveness of OSNs to odorous molecules and pheromones is based on distinct receptors in their chemosensory membrane; consequently, olfactory receptors play a key role for a reliable recognition and an accurate processing of chemosensory information. They are therefore considered as key elements for an understanding of the principles and mechanisms underlying the sense of smell. The repertoire of olfactory receptors in mammals encompasses hundreds of different receptor types which are highly diverse and expressed in distinct subcompartments of the nose. Accordingly, they are categorized into several receptor families, including odorant receptors (ORs), vomeronasal receptors (V1Rs and V2Rs), trace amine-associated receptors (TAARs), formyl peptide receptors (FPRs), and the membrane guanylyl cyclase GC-D. This large and complex receptor repertoire is the basis for the enormous chemosensory capacity of the olfactory system

Distinct subfamilies of odorant binding proteins in locust (Orthoptera, Acrididae) : molecular evolution, structural variation and sensilla-specific expression

Odorant binding proteins (OBPs) play an important role in insect olfaction, facilitating transportation of odorant molecules in the sensillum lymph. While most of the researches are concentrated on Lepidopteran and Dipteran species, our knowledge about Orthopteran species is still very limited. In this study, we have investigated OBPs of the desert locust Schistocerca gregaria, a representative Orthopteran species. We have identified 14 transcripts from a S. gregaria antennal transcriptome encoding SgreOBPs, and recapitulated the phylogenetic relationship of SgreOBPs together with OBPs from three other locust species. Two conserved subfamilies of classic OBPs have been identified, named I-A and II-A, exhibiting both common and subfamily-specific amino acid motifs. Distinct evolutionary features were observed for subfamily I-A and II-A OBPs. Surface topology and interior cavity were elucidated for OBP members from the two subfamilies. Antennal topographic expression revealed distinct sensilla- and cellular- specific expression patterns for SgreOBPs from subfamily I-A and II-A. These findings give first insight into the repertoire of locust OBPs with respect to their molecular and evolutionary features as well as their expression in the antenna, which may serve as an initial step to unravel specific roles of distinct OBP subfamilies in locust olfaction

Chemo- and Thermosensory Responsiveness of Grueneberg Ganglion Neurons Relies on Cyclic Guanosine Monophosphate Signaling Elements

Neurons of the Grueneberg ganglion (GG) in the anterior nasal region of mouse pups respond to cool temperatures and to a small set of odorants. While the thermosensory reactivity appears to be mediated by elements of a cyclic guanosine monophosphate (cGMP) cascade, the molecular mechanisms underlying the odor-induced responses are unclear. Since odor-responsive GG cells are endowed with elements of a cGMP pathway, specifically the transmembrane guanylyl cyclase subtype GC-G and the cyclic nucleotide-gated ion channel CNGA3, the possibility was explored whether these cGMP signaling elements may also be involved in chemosensory GG responses. Experiments with transgenic mice deficient for GC-G or CNGA3 revealed that GG responsiveness to given odorants was significantly diminished in these knockout animals. These findings suggest that a cGMP cascade may be important for both olfactory and thermosensory signaling in the GG. However, in contrast to the thermosensory reactivity, which did not decline over time, the chemosensory response underwent adaptation upon extended stimulation, suggesting that the two transduction processes only partially overlap. Copyright (C) 2011 S. Karger AG, Base

Receptors Responsive to Protein Breakdown Products in G-Cells and D-Cells of Mouse, Swine and Human

Monitoring the luminal content in the stomach is of vital importance for adjusting the gastric activities, including the release of gastric hormones such as gastrin. Our previous studies have shown that in mice the gastrin-secreting G-cells express receptor types which are responsive to amino acids. Since the pig is considered as more suitable model for studying gastro-physiological aspects relevant for men, in this study we have analyzed the distribution of G-cells and D-cells in the gastric antrum of men, swine, and mouse and the expression of receptor types which may render these cells responsiveness to protein breakdown products. The results indicate that the number of G-cells per antral invagination was significantly higher in swine and human compared to mice and also the distribution pattern of G-cells differed between the species. The molecular phenotyping revealed that the receptors GPRC6A and CaSR were also expressed in G-cells and in a subpopulation of D-cells from swine and men. As an additional receptor type, the peptone-receptor GPR92, was found to be expressed in G-cells and a subpopulation of D-cells; this receptor type may be particular suitable for sensing protein breakdown products and thus be a key element to adjust the activity of G-cells and D-cells according to the progress of the digestive processes in the stomach. In search for elements of an intracellular signaling cascade it was found that G-cells express the G-protein subunit Gαq as well as the phospholipase C subtype PLCβ3; in contrast, D-cells expressed the subtype PLCβ2 and neither Gαq. These results indicate that there are significant species differences concerning the number and distribution pattern, but not concerning the molecular phenotype of the gastric endocrine cells. However, G-cells and D-cells significantly differ from each other regarding the repertoire of receptors and signaling elements

Odorant binding proteins of the desert locust Schistocerca gregaria (Orthoptera, Acrididae) : topographic expression patterns in the antennae

Odorant binding proteins (OBPs) enriched in the sensillum lymph are instrumental in facilitating the transfer of odorous molecules to the responsive receptors. In Orthopteran locust species, an in-depth understanding of this important soluble protein family is still elusive. In a previous study, we have demonstrated that the repertoire of locust OBPs can be divided into four major clades (I–IV) on the phylogenetic scale and for representatives of subfamily I-A and II-A a distinct sensilla-specific expression pattern was determined. In this study, by focusing on a representative locust species, the desert locust Schistocerca gregaria, we have explored the antennal topographic expression for representative OBPs of other subfamilies. First, subtypes of subfamily III-A and III-B were exclusively found in sensilla chaetica. Then, a similar expression pattern in this sensillum type was observed for subfamily I-B subtypes, but with a distinct OBP that was expressed in sensilla coeloconica additionally. Moreover, the atypical OBP subtype from subfamily IV-A was expressed in a subpopulation of sensilla coeloconica. Last, the plus-C type-B OBP subtype from subfamily IV-B seems to be associated with all four antennal sensillum types. These results profile diversified sensilla-specific expression patterns of the desert locust OBPs from different subfamilies and complex co-localization phenotypes of distinct OBP subtypes in defined sensilla, which provide informative clues concerning their possible functional mode as well as a potential interplay among OBP partners within a sensillum

Band-like arrangement of taste-like sensory cells at the gastric groove: evidence for paracrine communication

The discovery of taste-related elements within the gastrointestinal tract has led to a growing interest in the mechanisms and physiological significance of chemosensory monitoring of chymus composition. Previous work suggests that brush cells located in the "gastric groove," which parallels the "limiting ridge," a structure in rodents that divides the fundus from the corpus, are candidate sensory cells. A novel sectioning technique revealed that these cells are arranged in a palisade-like manner forming a band which borders the whole length of the corpus epithelium. Using transgenic PLC beta 2 promoter-GFP mice and specific antibodies, we have demonstrated that most of these cells express gustducin, PLC beta 2, and TRPM5; typical signaling proteins of gustatory sensory "type II" cells. These molecular features strongly suggest that the cells may be capable of sensing nutrient or non-nutrient constituents of the ingested food. Since there is no evidence that brush cells are endocrine cells, attempts were made to explore how such putative chemosensory cells might transmit the information to "effector" cells. It was found that most of the cells express the neuronal nitric oxide synthase (NOS) suggesting some paracrine interaction with adjacent cells. Moreover, they also express choline acetyltransferase (ChAT) as well as the vesicular protein SNAP25, indicating the potential for cholinergic transmission, possibly with subjacent enteric nerve fibers