Fujian Key Laboratory of Traditional Chinese Veterinary Medicine and Animal Health, Fuzhou, 350002, China.
Key Laboratory of Animal Embryo Engineering and Molecular Breeding of Hubei Province, Wuhan, 430064, China.
BMC Genomics. 2019 Jan 19;20(1):66. doi: 10.1186/s12864-019-5436-4.
The diversity of avian eggshell colour plays important biological roles in ensuring successful reproduction. Eggshell colour is also an important trait in poultry, but the mechanisms underlying it are poorly understood in ducks. This study aimed to provide insights into the mechanism of blue-green eggshell colour generation.
Here, white-shelled ducks (HBR) and blue-green-shelled ducks (HQR) were selected from Putian black ducks, and white-shelled ducks (BBR) were selected from Putian white ducks. Transcriptional changes in the shell gland were analysed using RNA-sequencing on the Illumina HiSeq 2500. Twenty-seven individual cDNA libraries were sequenced and generated an average of 7.35 million reads per library; 70.6% were mapped to the duck reference genome, yielding an average of 13,794 genes detected, which accounted for approximately 86.39% of all 15,967 annotated duck genes. A total of 899 differentially expressed genes (DEGs) were detected between the HQR and BBR groups, and 373 DEGs were detected between the HQR and HBR groups. We analysed the DEGs in the HQR-vs-BBR and HQR-vs-HBR comparisons. None of these DEGs were directly involved in the eggshell pigmentation process in HQR-vs-HBR, while UDP-glucuronosyltransferase 2A2 (UGT2A2) and UDP-glucuronosyltransferase 1-1-like (UGT1-1-like), which participate in biliverdin breakdown, were two of the DEGs in HQR-vs-BBR. In the RT-qPCR results, delta-aminolevulinic acid synthase 1 (ALAS1) and EPRS glutamyl-prolyl-tRNA synthetase were significantly upregulated in the HBR group compared with the HQR and BBR groups (P < 0.05). Haem oxygenase (HMOX1) was significantly downregulated in BBR compared with HQR and HBR (P < 0.05). Biliverdin reductase A (BLVRA), GUSB glucuronidase beta, cytochrome c-type haem lyase, protohaem IX farnesyltransferase and UGT2A2 were significantly upregulated in HBR and BBR compared with HQR (P < 0.05).
We conducted a comparative transcriptome analysis of the shell glands of Putian white ducks and Putian black ducks. None of the differentially regulated pathways were directly involved in the eggshell pigmentation process in the HQR-vs-HBR comparison, while 2 DEGs related to biliverdin breakdown were found in HQR-vs-BBR. Based on the RT-qPCR results, we can speculate that both HQR and HBR can produce biliverdin, but HBR cannot accumulate it. Compared with HQR, BBR produced less biliverdin and did not accumulate it.
禽类蛋壳颜色的多样性在确保成功繁殖方面起着重要的生物学作用。蛋壳颜色也是家禽的一个重要特征，但在鸭子中，其背后的机制还知之甚少。本研究旨在深入了解蓝绿色蛋壳颜色形成的机制。
本研究从莆田黑鸭中选择了白皮鸭（HBR）和蓝绿皮鸭（HQR），并从莆田白鸭中选择了白皮鸭（BBR）。使用 Illumina HiSeq 2500 对蛋壳腺进行 RNA 测序，分析转录组变化。共测序 27 个 cDNA 文库，每个文库平均产生 735 万个reads；70.6%被映射到鸭参考基因组，平均检测到 13794 个基因，约占所有 15967 个鸭注释基因的 86.39%。HQR 和 BBR 组之间共检测到 899 个差异表达基因（DEGs），HQR 和 HBR 组之间检测到 373 个 DEGs。我们分析了 HQR-vs-BBR 和 HQR-vs-HBR 比较中的差异表达基因。在 HQR-vs-HBR 中，这些 DEGs 都没有直接参与蛋壳色素沉着过程，而在 HQR-vs-BBR 中，参与胆绿素分解的 UDP-葡萄糖醛酸基转移酶 2A2（UGT2A2）和 UDP-葡萄糖醛酸基转移酶 1-1 样（UGT1-1-like）是两个 DEGs。在 RT-qPCR 结果中，与 HQR 和 BBR 组相比，HBR 组 delta-氨基酮戊酸合酶 1（ALAS1）和 EPRS 谷氨酸酰基脯氨酸 tRNA 合成酶明显上调（P<0.05）。与 HQR 和 HBR 相比，BBR 中的血红素加氧酶（HMOX1）明显下调（P<0.05）。与 HQR 相比，BVRRA、GUSB 葡糖醛酸酶β、细胞色素 c 型血红素裂解酶、原卟啉 IX 法呢基转移酶和 UGT2A2 在 HBR 和 BBR 中明显上调（P<0.05）。
我们对莆田白鸭和莆田黑鸭的蛋壳腺进行了比较转录组分析。在 HQR-vs-HBR 比较中，没有一个差异调控途径直接参与蛋壳色素沉着过程，而在 HQR-vs-BBR 中发现了两个与胆绿素分解有关的 DEGs。根据 RT-qPCR 结果，我们可以推测 HQR 和 HBR 都可以产生胆绿素，但 HBR 不能积累它。与 HQR 相比，BBR 产生的胆绿素较少，且不能积累。
