Ramadan Sherif, Nowier Amira M, Hori Yusuke, Inoue-Murayama Miho
Wildlife Research Center, Kyoto University, Kyoto, Japan.
Faculty of Veterinary Medicine, Benha University, Moshtohor, Egypt.
PLoS One. 2018 Feb 7;13(2):e0191119. doi: 10.1371/journal.pone.0191119. eCollection 2018.
Temperament traits such as fearfulness are important as they define an animal's responses to its environment and handling. The increasing automation of daily tasks and growing population limits contact between camels and humans. Such limitations contribute to fear of humans and changes in physical environment. Monoamine oxidase A (MAOA) and androgen receptor (AR) genes are important candidates associated with mammal personality. In our analysis, MAOA exon 15 showed no polymorphism but a novel polymorphism was seen in the camel AR exon 1; 16, 17, 18, and 19 glutamine repeats were detected. We genotyped 138 camels belonging to four Egyptian breeds: Maghrabi (n = 90), Sudani (n = 15), Somali (n = 23), and Baladi (n = 10) for AR. Out of the 90 genotyped Maghrabi camels, we evaluated responses of 33 and 32 mature females to a novel object and exposure to an unfamiliar person, respectively. AR gene showed a significant association based on the principal component (PC) score, which indicated the fear of human touch, and the PC score indicates fear during interaction with novel objects. Individuals carrying a shorter genotype in homozygote (S/S) were found to be more fearful. Furthermore, we found that Sudani and Somali breeds had a higher frequency of shorter genotype (S/S), which was associated with increased fearfulness. These findings reflect the behavioral tendency and consequently, affect the use of this breed. This is the first report showing the role of AR glutamine repeats influencing a behavioral trait in dromedary camels and leading to inter-breed differences. Fear-related traits reported here are important because camels cope with various types of stresses and fear, resulting from the demands of intensive production systems and racing events. However, further studies, employing functional genomics and linkage analysis are necessary for confirming the relationship between fearfulness and genetic variation.
诸如恐惧等气质特征很重要，因为它们决定了动物对其环境和处理方式的反应。日常任务自动化程度的提高和人口的增长限制了骆驼与人类之间的接触。这些限制导致了骆驼对人类的恐惧以及物理环境的变化。单胺氧化酶A（MAOA）和雄激素受体（AR）基因是与哺乳动物性格相关的重要候选基因。在我们的分析中，MAOA外显子15未显示多态性，但在骆驼AR外显子1中发现了一种新的多态性；检测到16、17、18和19个谷氨酰胺重复序列。我们对属于四个埃及品种的138头骆驼进行了AR基因分型：马格里布（n = 90）、苏丹（n = 15）、索马里（n = 23）和巴拉丁（n = 10）。在90头基因分型的马格里布骆驼中，我们分别评估了33头和32头成年雌性对新物体的反应以及对陌生人的接触反应。基于主成分（PC）得分，AR基因显示出显著关联，该得分表明对人类触摸的恐惧，并且PC得分表明在与新物体互动时的恐惧。发现纯合子中携带较短基因型（S/S）的个体更恐惧。此外，我们发现苏丹和索马里品种中较短基因型（S/S）的频率较高，这与恐惧增加有关。这些发现反映了行为倾向，因此影响了该品种的使用。这是第一份显示AR谷氨酰胺重复序列在单峰骆驼行为特征中发挥作用并导致品种间差异的报告。这里报道的与恐惧相关的特征很重要，因为骆驼要应对集约化生产系统和比赛活动需求所带来各种压力和恐惧。然而，需要进一步采用功能基因组学和连锁分析的研究来确认恐惧与基因变异之间的关系。
