Extrathyroidal thyroid hormone activation in ring doves

Simple item page
dc.contributor.authorRieman, James Davisen
dc.contributor.departmentBiologyen
dc.date.accessioned2014-03-14T21:31:46Zen
dc.date.adate2009-03-14en
dc.date.available2014-03-14T21:31:46Zen
dc.date.issued1990en
dc.date.rdate2009-03-14en
dc.date.sdate2009-03-14en
dc.description.abstractThe characteristics of 5’deiodinase (5’D) were studied in the postmitochondrial fraction (PMF) of liver homogenates from adult and developing ring doves (Streptopelia risoria). The 5’D assays were performed in the presence of abundant substrate, reverse triiodothyronine (rT3), cofactor (dithiothreitol) and trace amounts of I¹²⁵-rT3. 5’D activity was measured as I¹²⁵ released from the labelled rT3 during the assay incubation time. The 5’D assay was validated for all ages studied to assure that the initial reaction velocity of the enzyme was measured. Using the validated assay conditions the following characteristics were found in adult doves: the apparent K<sub>m</sub> was 0.44 μM rT3, V<sub>max</sub> was 255 pmol rT3 degraded/min-mg PMF protein. The 5’D activity was completely inhibited by 1.0 mM PTU and 50% inhibited by the addition of 18.0 μM thyroxine (T4) in the presence of 4.0 μM rT3. Activity was maximal at pH 8.04 and at 37.5 C. The K<sub>m</sub> of the enzyme did not change throughout development (1 day prehatch to adult). The 5’D specific activity (rT3 degraded/min-mg PMF protein) was highest during early development (1 day prehatch to 7 days post-hatch), after which it gradually decreased with increasing age. The liver 5’D activity/gram of body weight was highest during the first seven days posthatch. This period of high potential triiodothyronine (T3) production corresponds with the observed period of greatest increase in plasma thyroid hormone concentrations during the first 6-8 days posthatch in ring doves. These results are the first demonstration of initial velocity 5’D activity during development in an altricial bird species and demonstrate a correlation between hepatic 5’D activity and plasma thyroid hormone concentrations during development in ring doves.en
dc.description.degreeMaster of Scienceen
dc.format.extentviii, 62 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-03142009-040750en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03142009-040750/en
dc.identifier.urihttp://hdl.handle.net/10919/41625en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1990.R537.pdfen
dc.relation.isformatofOCLC# 23657957en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1990.R537en
dc.subject.lcshColumbidaeen
dc.subject.lcshPigeons -- Physiologyen
dc.titleExtrathyroidal thyroid hormone activation in ring dovesen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineBiologyen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
LD5655.V855_1990.R537.pdf
Size:
2.82 MB
Format:
Adobe Portable Document Format
Description:
Download

Collections

Masters Theses