Characterization of very-low density lipoprotein particle diameter dynamics in relation to egg production in a passerine bird

Abstract

SUMMARY During avian egg production, oestrogen mediates marked increases in hepatic lipid production and changes in the diameter of assembled very-low density lipoprotein (VLDL). A nearly complete shift from generic VLDL (∼70 nm in diameter), which transports lipids to peripheral tissues, to yolk-targeted VLDL (VLDLy) (∼30 nm), which supplies the yolk with energy-rich lipid, has been observed in the plasma of laying domestic fowl. We validated an established dynamic laser scattering technique for a passerine songbird Taeniopygia guttata, the zebra finch, to characterize the dynamics of VLDL particle diameter distribution in relation to egg production. We predicted that non-gallinaceous avian species that have not been selected for maximum egg production would exhibit less dramatic shifts in lipid metabolism during egg production. As predicted, there was considerable overlap between the VLDL particle diameter distributions of laying and non-laying zebra finches. But unexpectedly, non-laying zebra finches had VLDL diameter distributions that peaked at small particles and had relatively few large VLDL particles. As a result, laying zebra finches, in comparison, had diameter distributions that were shifted towards larger VLDL particles. Nevertheless,laying zebra finches, like laying chickens, had larger proportions of particles within proposed VLDLy particle diameter ranges than non-laying zebra finches (e.g. sVLDLy: 50% vs 37%). Furthermore, zebra finches and chickens had similar modal (29.7 nm in both species) and median (32.7 nm vs 29.6 nm) VLDL particle diameters during egg production. Therefore,although zebra finches and chickens exhibited opposing directional shifts in VLDL particle diameter distribution during egg production, the modifications to VLDL particle structure in both species resulted in the realization of a common goal, i.e. to produce and maintain a large proportion of small VLDL particles of specific diameters that are capable of being incorporated into newly forming egg yolks.)

Pemanfaatan Tepung Kulit Bawang Merah (Allium ascalonicum) Sebagai Imbuhan Pakan Terhadap Penampilan, Profil Darah Dan Kolesterol Pada Puyuh Petelur

“…Kolesterol berfungsi sebagai bahan untuk sintesis hormon steroid, unsur garam empedu, dan prekursor sintesis kuning telur (vitelogenin) Meer et al, 2008;Bhat dan Bhat, 2015). Vitelogenin disintesis di hati yang dikemas dalam bentuk VLDL (Very Low Density Lipoprotein), kemudian di transfer ke dalam ovarium dan diakumulasikan dalam folikel sebagai kuning telur (Salvante et al, 2007). Oleh karena itu, Piliang dan Djojosoebagio (2008) mengemukakan pemberian pakan yang kandungan serat kasarnya tinggi pada unggas dapat menurunkan kadar kolesterol darah dan kuning telur.…”

What comes first, the zebra finch or the egg: temperature-dependent reproductive, physiological and behavioural plasticity in egg-laying zebra finches

“…Only particles 25-44·nm in diameter have been observed distal to the basal lamina of domesticated fowl (Perry and Gilbert, 1979;Griffin and Perry, 1985;Griffin and Hermier, 1988;Walzem et al, 1999). Egg-laying zebra finches and chickens have been found to maintain a larger proportion of circulating VLDL particles within this diameter range than non-laying females (Salvante et al, 2007). The modal and median particle diameter and the range (i.e.…”

Dioxins in the Food Chain: Contamination Fingerprint Analysis in Breeding Hens, Hatching Eggs and Broilers

“…For example, in the broilers and breeding hens muscle fat profiles, the average relative concentration of OCDD was 52% and 53% lower, comparatively to the wood shavings and hatching eggs profile, respectively [10]. On the other hand, the average relative concentration of 1,2,3,7,8-PeCDD, 1,2,3,6,7,8-HxCDD and 1,2,3,4,6,7,8-HpCDD in the broilers and breeding hens muscle fat profiles was 50% -97% higher when compared with the litters and hatching eggs profiles.…”

“…The smaller diameter of VLDLy is thought to be critical for enabling the particles to pass through the pores in the granulosa basal lamina of the ovary, allowing them access to the developing ovarian follicles. VLDLy particles are in high plasma concentrations in laying hens and are resistant to hydrolysis by extra-ovarian tissues which preserves the triglycerol-rich VLDLy for uptake by the developing ovarian follicles [10].…”