School of Animal Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
School of Animal Sciences, Virginia Tech, Blacksburg, VA 24061, USA.
Poult Sci. 2023 Sep;102(9):102875. doi: 10.1016/j.psj.2023.102875. Epub 2023 Jun 17.
During the transition from incubation to hatch, the chicks shift from obtaining nutrients from the yolk sac to the intestine. The yolk sac tissue (YST) and small intestine serve as biological barriers between the yolk or gut contents and the blood circulation. These barriers must maintain structural integrity for optimal nutrient uptake as well as protection from pathogens. The objective of this study was to investigate the effect of high incubation temperature on mRNA abundance of the tight junction (TJ) proteins zona occludens 1 (ZO1), occludin (OCLN), claudin 1 (CLDN1), and junctional adhesion molecules A and 2 (JAMA, JAM2) and the heat shock proteins (HSP70 and HSP90) in the YST and small intestine of embryonic broilers. Broiler eggs were incubated at 37.5°C. On embryonic day 12 (E12), half of the eggs were switched to 39.5°C. YST samples were collected from E7 to day of hatch (DOH), while small intestinal samples were collected from E17 to DOH. The temporal expression of TJ protein mRNA from E7 to DOH at 37.5°C and the effect of incubation temperature from E13 to DOH were analyzed by one-way and two-way ANOVA, respectively and Tukey's test. Significance was set at P < 0.05. The temporal expression pattern of ZO1, OCLN, and CLDN1 mRNA showed a pattern of decreased expression from E7 to E13 followed by an increase to DOH. High incubation temperature caused an upregulation of ZO1 and JAM2 mRNA in the YST and small intestine. Using in situ hybridization, OCLN and JAMA mRNA were detected in the epithelial cells of the YST. In addition, JAMA mRNA was detected in epithelial cells of the small intestine, whereas JAM2 mRNA was detected in the vascular system of the villi and lamina propria. In conclusion, the YST expressed mRNA for TJ proteins and high incubation temperature increased ZO1 and JAM2 mRNA. This suggests that the TJ in the vasculature of the YST and intestine is affected by high incubation temperature.
在孵化向出雏的转变过程中，雏鸡从卵黄囊获取营养转变为从肠道获取营养。卵黄囊组织（YST）和小肠作为卵黄或肠道内容物与血液循环之间的生物屏障。这些屏障必须保持结构完整性，以实现最佳的营养吸收，并防止病原体进入。本研究的目的是研究高温孵化对胚胎肉鸡卵黄囊和小肠紧密连接（TJ）蛋白闭合蛋白 1（ZO1）、紧密连接蛋白（OCLN）、 Claudin1（CLDN1）和连接黏附分子 A 和 2（JAMA、JAM2）以及热休克蛋白（HSP70 和 HSP90）mRNA 丰度的影响。肉鸡卵在 37.5°C 下孵化。在胚胎第 12 天（E12），一半的卵被切换到 39.5°C。从 E7 到出雏日（DOH）收集 YST 样本，从 E17 到 DOH 收集小肠样本。在 37.5°C 下从 E7 到 DOH 的 TJ 蛋白 mRNA 的时间表达以及从 E13 到 DOH 的孵化温度的影响分别通过单向和双向 ANOVA 以及 Tukey 检验进行分析。显著性水平设为 P < 0.05。ZO1、OCLN 和 CLDN1mRNA 的时间表达模式表现为从 E7 到 E13 的表达减少，随后到 DOH 增加。高温孵化导致 YST 和小肠中 ZO1 和 JAM2mRNA 的上调。通过原位杂交，在 YST 的上皮细胞中检测到 OCLN 和 JAMA mRNA。此外，在小肠的上皮细胞中检测到 JAMA mRNA，而在绒毛和固有层的血管系统中检测到 JAM2mRNA。总之，YST 表达 TJ 蛋白的 mRNA，高温孵化增加了 ZO1 和 JAM2mRNA。这表明 YST 和肠道的血管 TJ 受到高温孵化的影响。
