Robertson Hugh M, Wanner Kevin W
Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Genome Res. 2006 Nov;16(11):1395-403. doi: 10.1101/gr.5057506. Epub 2006 Oct 25.
The honey bee genome sequence reveals a remarkable expansion of the insect odorant receptor (Or) family relative to the repertoires of the flies Drosophila melanogaster and Anopheles gambiae, which have 62 and 79 Ors respectively. A total of 170 Or genes were annotated in the bee, of which seven are pseudogenes. These constitute five bee-specific subfamilies in an insect Or family tree, one of which has expanded to a total of 157 genes encoding proteins with 15%-99% amino acid identity. Most of the Or genes are in tandem arrays, including one with 60 genes. This bee-specific expansion of the Or repertoire presumably underlies their remarkable olfactory abilities, including perception of several pheromone blends, kin recognition signals, and diverse floral odors. The number of Apis mellifera Ors is approximately equal to the number of glomeruli in the bee antennal lobe (160-170), consistent with a general one-receptor/one-neuron/one-glomerulus relationship. The bee genome encodes just 10 gustatory receptors (Grs) compared with the D. melanogaster and A. gambiae repertoires of 68 and 76 Grs, respectively. A lack of Gr gene family expansion primarily accounts for this difference. A nurturing hive environment and a mutualistic relationship with plants may explain the lack of Gr family expansion. The Or family is the most dramatic example of gene family expansion in the bee genome, and characterizing their caste- and sex-specific gene expression may provide clues to their specific roles in detection of pheromone, kin, and floral odors.
蜜蜂基因组序列显示，相对于果蝇（Drosophila melanogaster）和冈比亚按蚊（Anopheles gambiae）的嗅觉受体（Or）库而言，昆虫嗅觉受体家族有显著扩张，果蝇和冈比亚按蚊分别有62个和79个嗅觉受体。蜜蜂中总共注释了170个Or基因，其中7个为假基因。在昆虫Or家族树中，这些基因构成了5个蜜蜂特有的亚家族，其中一个亚家族已扩展到总共157个基因，这些基因编码的蛋白质氨基酸同一性为15% - 99%。大多数Or基因成串联排列，其中一个串联阵列包含60个基因。Or库的这种蜜蜂特异性扩张可能是其卓越嗅觉能力的基础，这些能力包括对几种信息素混合物、亲缘识别信号以及多种花香气味的感知。意大利蜜蜂（Apis mellifera）的Or数量大约与蜜蜂触角叶中的神经小球数量相等（160 - 170个），这与一般的一个受体/一个神经元/一个神经小球的关系一致。与果蝇和冈比亚按蚊分别有68个和76个味觉受体（Grs）的库相比，蜜蜂基因组仅编码10个味觉受体。Grs基因家族缺乏扩张是造成这种差异的主要原因。培育性蜂群环境以及与植物的共生关系可能解释了Grs基因家族缺乏扩张的现象。Or家族是蜜蜂基因组中基因家族扩张最显著的例子，对其在不同蜂型和性别中的基因表达进行表征，可能为它们在检测信息素、亲缘关系和花香气味中的特定作用提供线索。
