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Titolo:
Follicular development and plasma yolk precursor dynamics through the laying cycle in the European starling (Sturnus vulgaris)
Autore:
Challenger, WO; Williams, TD; Christians, JK; Vezina, F;
Indirizzi:
Simon Fraser Univ, Dept Biol Sci, Burnaby, BC V5A 1S6, Canada Simon FraserUniv Burnaby BC Canada V5A 1S6 , Burnaby, BC V5A 1S6, Canada
Titolo Testata:
PHYSIOLOGICAL AND BIOCHEMICAL ZOOLOGY
fascicolo: 3, volume: 74, anno: 2001,
pagine: 356 - 365
SICI:
1522-2152(200105/06)74:3<356:FDAPYP>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
FINCHES TAENIOPYGIA-GUTTATA; ZEBRA FINCHES; EGG-PRODUCTION; CLUTCH SIZE; RICH LIPOPROTEINS; VITELLOGENIN; PHYSIOLOGY; BIRDS; HEN; SYMMORPHOSIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Agriculture,Biology & Environmental Sciences
Life Sciences
Citazioni:
58
Recensione:
Indirizzi per estratti:
Indirizzo: Williams, TD Simon Fraser Univ, Dept Biol Sci, 8888 Univ Dr, Burnaby, BC V5A 1S6, Canada Simon Fraser Univ 8888 Univ Dr Burnaby BC Canada V5A 1S6 nada
Citazione:
W.O. Challenger et al., "Follicular development and plasma yolk precursor dynamics through the laying cycle in the European starling (Sturnus vulgaris)", PHYSIOL B Z, 74(3), 2001, pp. 356-365

Abstract

We investigated the quantitative matching of plasma yolk precursor supply (the plasma pool) to follicle demand during yolk formation in European starlings (Sturnus vulgaris). Plasma concentrations of the two yolk precursors,vitellogenin (VTG) and very low density lipoprotein (VLDL), were only elevated coincident with rapid yolk development (RYD) and matched variation in total yolky follicle mass. VTG and VLDL were low (<0.4 <mu>g/mL and <4.2 mg/mL, respectively) in nonbreeders and prebreeders with no yolky follicles, and at clutch completion. They increased to 4.02 <mu>g/mL and 19.4 mg/mL inbirds with a full follicle hierarchy (F-1-F-4), and concentrations then remained high and actually increased up to the point where only a single, yolky (F-1) follicle remained. However, there was some evidence for mismatching of supply and demand: (a) precursor concentrations increased throughout the laying cycle even though the number of developing follicles decreased. We suggest that this is because of a requirement to maintain a large precursor pool to maintain high uptake rates; and (b) in birds with a full follicle hierarchy, precursor concentrations were negatively correlated with totalfollicle mass. This suggests that high uptake rates in large follicles canactually deplete circulating precursor concentrations. Plasma concentrations of both yolk precursors increased rapidly in the early morning with (predicted) time after ovulation, consistent with a lack of fine control of precursor concentrations. However, mean plasma VTG concentrations did not differ between morning or evening samples. In contrast, plasma VLDL concentrations were lower in the morning (16.8 mg/mL) than in the evening (22.9 mg/mL). Although there is marked individual variation in plasma VTG and VLDL (four- to eightfold), both precursors were repeatable in the short term (24 h),and plasma VTG was repeatable over a 14-d interval between successive breeding attempts.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/09/20 alle ore 09:41:01