Lactation and gestation are among the physiological events that trigger the most intense changes in body calcium (Ca) fluxes. Along with the composition of the animal 2021 diet, these events are suspected to impact the Ca isotopic composition of Ca body reservoirs but their dynamics are poorly understood. In this study, we monitored a group of domestic sows across a full reproduction cycle. We collected tissues and fluids (blood, urine, milk, colostrum, umbilical blood, adult and piglet bones) at different steps of gestation and lactation, and analyzed their Ca isotopic compositions (i.e. δ44/42Ca) by means of multi-collector inductively coupled plasma mass spectrometry. Among other results, we report the first observations of Ca isotopic fractionation between maternal and umbilical blood (Δ44/42Caumbilical blood-sow blood = -0.18 ± 0.11‰, n = 3). Our data also highlight that gestation and lactation periods are characterized by small diet-bone Ca isotopic offsets (Δ44/42Cabone-diet = -0.28 ± 0.11‰, n = 3), with 44Ca-enriched blood compositions during nursing (Δ44/42Canursing blood-gestation blood = $+ 0.42{\rm{\,\,}}_{ - 0.12}^{ + 0.11}$‰, n = 3). Under the light of an up-to-date mammalian box model, we explored different scenarios of gestation and lactation Ca fluxes experienced by a sow-like animal. These simulations suggest that gestation changes on body δ44/42Ca values may result from the intensification of Ca absorption by the animal, whereas the production of 44Ca-depleted milk is the main driver for the 44Ca enrichment in blood during lactation. In addition, our results also support that bone mineralization could be associated with a more restricted Ca isotopic fractionation than previously envisioned. Together, these results refine the framework of Ca isotope applications, notably regarding the monitoring of human bone balance and the study of species and ecosystems from the present and the past.

中文翻译：

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哺乳动物模型中钙同位素组成的哺乳和妊娠控制。

哺乳和妊娠是引发体内钙 (Ca) 通量最剧烈变化的生理事件之一。与 2021 年动物饮食的组成一起，这些事件被怀疑会影响 Ca 体库的 Ca 同位素组成，但对其动态知之甚少。在本研究中，我们对一组家养母猪进行了完整的繁殖周期监测。我们采集了妊娠和哺乳期不同阶段的组织和体液（血液、尿液、牛奶、初乳、脐血、成年和仔猪骨骼），并通过多收集器电感耦合分析了它们的Ca同位素组成（即δ44/42Ca）。等离子体质谱法。在其他结果中，我们报告了母血和脐血之间 Ca 同位素分馏的首次观察结果（Δ44/42Caumbilical 血母猪血 = -0.18 ± 0.11‰，n = 3）。我们的数据还强调，妊娠和哺乳期的特点是饮食骨钙同位素偏移小（Δ44/42Cabone-diet = -0.28 ± 0.11‰，n = 3），在护理期间富含 44Ca 的血液成分（Δ44/42Canursing 血液-妊娠血 = $+ 0.42{\rm{\,\,}}_{ - 0.12}^{ + 0.11}$‰, n = 3)。在最新的哺乳动物盒模型的光照下，我们探索了母猪样动物经历的妊娠和哺乳期 Ca 通量的不同情况。这些模拟表明，妊娠期间体内 δ44/42Ca 值的变化可能是由于动物对 Ca 吸收的增强所致，而缺乏 44Ca 的牛奶的产生是泌乳期间血液中 44Ca 富集的主要驱动因素。此外，我们的结果还支持骨矿化可能与比以前设想的更受限制的 Ca 同位素分馏有关。总之，这些结果完善了 Ca 同位素应用的框架，特别是在监测人类骨骼平衡以及研究现在和过去的物种和生态系统方面。