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Demonstration of peptide and free amino acid absorption by sheep forestomach epithelium using parabiotic chambers and identification of H⁺/peptide and free amino acid transport proteins in sheep omasal epithelium and bo,+ amino acid transport proteins in pig jejunal epithelium by expression of mRNA in Xenopus laevis oocytes

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dc.contributor.authorMatthews, James Clydeen
dc.contributor.committeechairWebb, Kenneth E. Jr.en
dc.contributor.committeememberBender, Patrick A.en
dc.contributor.committeememberGwazdauskas, Francis C.en
dc.contributor.committeememberHerbein, Joseph H. Jr.en
dc.contributor.committeememberKornegay, Ervin T.en
dc.contributor.committeememberWong, Eric A.en
dc.contributor.departmentAnimal Scienceen
dc.date.accessioned2014-03-14T21:23:10Zen
dc.date.adate2008-11-18en
dc.date.available2014-03-14T21:23:10Zen
dc.date.issued1995-04-12en
dc.date.rdate2008-11-18en
dc.date.sdate2008-11-18en
dc.description.abstractThe absorption of methionine and methionylglycine (Met-Gly) across sheep (average BW = 38 kg) ruminal and omasal epithelia was studied using parabiotic chambers. Ruminal tissue demonstrated a greater ability to accumulate both substrates. Omasal tissue demonstrated a greater ability to translocate methionine and Met-Gly and a greater total absorption of both. Intact Met-Gly was transferred across both tissues. More was hydrolyzed by omasal epithelia. Within tissues, the total absorption of substrates did not differ. Evidence for carrier-mediated absorption was not observed. The ability to express exogenous mRNA in defolliculated Xenopus laevis oocytes was developed using sucrose gradient size-fractionated poly(A)⁺ RNA (RNA) isolated from the jejunal epithelial tissue of pig (average BW = 33.8 kg). Compared to water-injected oocytes, RNA injected oocytes displayed greater rates of Nat-independent lysine and leucine absorption. RNA-induced uptake of lysine (Kt = 52 uM) and leucine (Kt = 97 uM) was inhibited by 5 mM leucine and lysine, respectively, by .2 mM cysteine, but not by 5 mM glutamate. RNA-induced lysine and leucine absorption also was inhibited when oocytes were injected with RNA plus DNA oligomers that were complementary to the cloned human kidney b⁰‘⁺ transporter. Oocytes were injected with RNA isolated from omasal epithelial tissue of sheep (average BW = 67.5 kg) to identify potential peptide and amino acid transport proteins. Injection of specific RNA fractions induced greater rates of glycylsarcosine (Gly-Sar) uptake, as compared to water injection of oocytes. Media pH of less than 6.5 was required for induced Gly-Sar uptake. Induced Gly-Sar uptake required a pH of less than 6.5, was saturable (Kt = .40 mM), and was inhibited by 5 mM carnosine, Met-Gly, glycylleucine, but not by glycine. The RNA-induced Gly-Sar absorption was completely inhibited when oocytes were co-injected with RNA and DNA oligomers that were complementary to the cloned rabbit H⁺/peptide cotransporter. When oocytes were assayed for their ability to absorb lysine, RNA-induced lysine absorption was determined to be Na⁺-independent and to display b⁰‘⁺-like transport activity. Collectively, these results indicate that sheep omasal epithelia possess the potential to absorb free and peptide-bound amino acids by non-mediated processes and possess mRNA that encode for Ht-dependent dipeptide and b⁰‘⁺ transport protein activity. mRNA that encodes for b⁰‘⁺-like transport activity was identified in the jejunal epithelium of growing pigs.en
dc.description.degreePh. D.en
dc.format.extentxiii, 186 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-11182008-063044en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-11182008-063044/en
dc.identifier.urihttp://hdl.handle.net/10919/40348en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V856_1995.M388.pdfen
dc.relation.isformatofOCLC# 33332419en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectbiological transporten
dc.subject.lccLD5655.V856 1995.M388en
dc.titleDemonstration of peptide and free amino acid absorption by sheep forestomach epithelium using parabiotic chambers and identification of H⁺/peptide and free amino acid transport proteins in sheep omasal epithelium and b<sup>o,+</sup> amino acid transport proteins in pig jejunal epithelium by expression of mRNA in Xenopus laevis oocytesen
dc.typeDissertationen
dc.type.dcmitypeTexten
thesis.degree.disciplineAnimal Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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