Knipple Douglas C, Rosenfield Claire-Lise, Nielsen Rasmus, You Kyung Man, Jeong Seong Eun
Department of Entomology, New York State Agricultural Experiment Station, Cornell University, Geneva, New York 14456, USA.
Genetics. 2002 Dec;162(4):1737-52. doi: 10.1093/genetics/162.4.1737.
Lepidopteran insects use sex pheromones derived from fatty acids in their species-specific mate recognition system. Desaturases play a particularly prominent role in the generation of structural diversity in lepidopteran pheromone biosynthesis as a result of the diverse enzymatic properties they have evolved. These enzymes are homologous to the integral membrane desaturases, which play a primary role in cold adaptation in eukaryotic cells. In this investigation, we screened for desaturase-encoding sequences in pheromone glands of adult females of eight lepidopteran species. We found, on average, six unique desaturase-encoding sequences in moth pheromone glands, the same number as is found in the genome database of the fly, Drosophila melanogaster, vs. only one to three in other characterized eukaryotic genomes. The latter observation suggests the expansion of this gene family in insects before the divergence of lepidopteran and dipteran lineages. We present the inferred homology relationships among these sequences, analyze nonsynonymous and synonymous substitution rates for evidence of positive selection, identify sequence and structural correlates of three lineages containing characterized enzymatically distinct desaturases, and discuss the evolution of this sequence family in insects.
鳞翅目昆虫在其物种特异性配偶识别系统中使用源自脂肪酸的性信息素。由于它们所进化出的多样酶特性，去饱和酶在鳞翅目昆虫性信息素生物合成的结构多样性产生过程中发挥着尤为突出的作用。这些酶与整合膜去饱和酶同源，整合膜去饱和酶在真核细胞的冷适应中起主要作用。在本研究中，我们在8种鳞翅目物种成年雌性的性信息素腺中筛选去饱和酶编码序列。我们发现，蛾类性信息素腺中平均有6个独特的去饱和酶编码序列，这与果蝇基因组数据库中的数量相同，而在其他已表征的真核生物基因组中只有1至3个。后一观察结果表明，该基因家族在鳞翅目和双翅目谱系分化之前就在昆虫中发生了扩张。我们展示了这些序列之间推断的同源关系，分析非同义替换率和同义替换率以寻找正选择的证据，确定了包含具有不同酶活性特征的去饱和酶的三个谱系的序列和结构相关性，并讨论了该序列家族在昆虫中的进化。
