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欧洲椋鸟(Sturnus vulgaris)产蛋周期中的卵泡发育和血浆卵黄前体动态变化。

Follicular development and plasma yolk precursor dynamics through the laying cycle in the European starling (Sturnus vulgaris).

作者信息

Challenger W O, Williams T D, Christians J K, Vézina F

机构信息

Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.

出版信息

Physiol Biochem Zool. 2001 May-Jun;74(3):356-65. doi: 10.1086/320427.

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 microg/mL and <4.2 mg/mL, respectively) in nonbreeders and prebreeders with no yolky follicles, and at clutch completion. They increased to 4.02 microg/mL and 19.4 mg/mL in birds with a full follicle hierarchy (F1-F4), and concentrations then remained high and actually increased up to the point where only a single, yolky (F1) 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 total follicle mass. This suggests that high uptake rates in large follicles can actually 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.

摘要

我们研究了欧洲椋鸟(Sturnus vulgaris)卵黄形成过程中血浆卵黄前体供应(血浆池)与卵泡需求的定量匹配情况。两种卵黄前体,即卵黄生成素(VTG)和极低密度脂蛋白(VLDL)的血浆浓度仅在快速卵黄发育(RYD)期间升高,并与总卵黄卵泡质量的变化相匹配。在没有卵黄卵泡的非繁殖鸟和繁殖前期鸟以及产卵结束时,VTG和VLDL含量较低(分别<0.4微克/毫升和<4.2毫克/毫升)。在具有完整卵泡等级(F1 - F4)的鸟类中,它们分别增加到4.02微克/毫升和19.4毫克/毫升,然后浓度保持在高位,实际上一直增加到只剩下单个卵黄(F1)卵泡的阶段。然而,有一些证据表明供应与需求不匹配:(a)尽管发育中的卵泡数量减少,但整个产卵周期中前体浓度仍在增加。我们认为这是因为需要维持一个大的前体池以保持高摄取率;(b)在具有完整卵泡等级的鸟类中,前体浓度与总卵泡质量呈负相关。这表明大卵泡中的高摄取率实际上会耗尽循环前体浓度。两种卵黄前体的血浆浓度在清晨随着排卵后的(预测)时间迅速增加,这与前体浓度缺乏精细控制一致。然而,早晨和晚上样本之间的平均血浆VTG浓度没有差异。相比之下,早晨的血浆VLDL浓度(16.8毫克/毫升)低于晚上(22.9毫克/毫升)。尽管血浆VTG和VLDL存在明显的个体差异(4至8倍),但两种前体在短期内(24小时)是可重复的,并且血浆VTG在连续繁殖尝试之间的14天间隔内也是可重复的。

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