College of Eco-Environmental Engineering, Qinghai University, 251 Ningda Road, Xining, 810016, Qinghai, China.
Qinghai Academy of Animal Science and Veterinary Medicine, Qinghai University, 1 Weier Road, Xining, 810016, Qinghai, China.
BMC Dev Biol. 2021 Apr 20;21(1):9. doi: 10.1186/s12861-021-00240-w.
Yaks have a strong adaptability to the plateau environment, which can be attributed to the effective oxygen utilization rate of their lung tissue. Elastic fibre confers an important adaptive structure to the alveolar tissues in yaks. However, little research has been focused on the structural development of lung tissues and the expression levels of elastic fibres in yaks after birth. Therefore, this study aimed to investigate the morphological changes of elastic fibers and expression profiles of fibre-formation genes in yak lungs at different growth stages and the relationship between these changes and plateau adaptation.
Histological staining was employed to observe the morphological changes in the lung tissue structure of yaks at four different ages: 1 day old, 30 days old, 180 days old and adult. There was no significant difference in the area of a single alveolus between the 1-day-old and 30-day-old groups (P-value > 0.05). However, the single alveolar area was gradually increased with an increase in age (P-value < 0.05). Elastic fibre staining revealed that the amount of elastic fibres in alveolar tissue was increased significantly from the ages of 30 days to 180 days (P-value < 0.05) and stabilized during the adult stage. Transcriptome analysis indicated that the highest levels of differentially expressed genes were found between 30 days of age and 180 days of age. KEGG analysis showed that PI3K-Akt signalling pathway and MAPK pathway, which are involved in fibre formation, accounted for the largest proportion of differentially expressed genes between 30 days of age and 180 days of age. The expression levels of 36 genes related to elastic fibre formation and collagen fibre formation were also analysed, and most of these genes were highly expressed in 30-day-old and 180-day-old yaks.
The content of elastic fibres in the alveolar tissue of yaks increases significantly after birth, but this change occurs only from 30 days of age to 180 days of age. Our study indicates that elastic fibres can improve the efficiency of oxygen utilization in yaks under harsh environmental conditions.
牦牛对高原环境具有很强的适应性，这可以归因于其肺组织的有效氧气利用率。弹性纤维赋予了牦牛肺泡组织重要的适应结构。然而，关于牦牛出生后肺组织的结构发育和弹性纤维的表达水平，研究甚少。因此，本研究旨在探讨不同生长阶段牦牛肺组织中弹性纤维的形态变化和纤维形成基因的表达谱，以及这些变化与高原适应的关系。
采用组织学染色观察了 4 个不同年龄（1 日龄、30 日龄、180 日龄和成年）牦牛肺组织的形态结构变化。1 日龄和 30 日龄组单个肺泡面积无显著差异（P 值>0.05）。然而，随着年龄的增长，单个肺泡面积逐渐增加（P 值<0.05）。弹性纤维染色显示，从 30 日龄到 180 日龄，肺泡组织中弹性纤维的数量显著增加（P 值<0.05），并在成年期保持稳定。转录组分析表明，30 日龄和 180 日龄之间差异表达基因的数量最高。KEGG 分析表明，涉及纤维形成的 PI3K-Akt 信号通路和 MAPK 通路在 30 日龄和 180 日龄之间的差异表达基因中占比最大。还分析了 36 个与弹性纤维形成和胶原纤维形成相关的基因的表达水平，这些基因在 30 日龄和 180 日龄的牦牛中表达水平较高。
牦牛肺泡组织中的弹性纤维含量在出生后显著增加，但这种变化仅发生在 30 日龄到 180 日龄之间。我们的研究表明，弹性纤维可以提高牦牛在恶劣环境条件下的氧气利用效率。
