Molecular characterization and evolution of a gene family encoding male-specific reproductive proteins in the African malaria vector Anopheles gambiae.
Molecular characterization and evolution of a gene family encoding male-specific reproductive proteins in the African malaria vector Anopheles gambiae.
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DOI：
10.1186/1471-2148-11-292
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发表时间：
2011-10-06
影响因子：
3.4
通讯作者：
della Torre, Alessandra
中科院分区：
文献类型：
--
作者：
Mancini, Emiliano;Baldini, Francesco;della Torre, Alessandra
背景：在交配过程中，主要的非洲热带疟疾媒介冈比亚按蚊s.s.将雄性附腺（MAG）蛋白作为固体物质（即“交配栓”）转移到雌性。这些蛋白质被假定为女性交配后反应的重要调节剂。为了了解这些蛋白质在A. gambiae复合体中，我们进行了基因序列和表达差异的一对parabolic基因AgAcp 34 A-1和AgAcp 34 A-2的进化分析。这些编码MAG特异性蛋白质，基于与果蝇的同源性，已被假设在精子活力和功能中发挥作用。结果：对6种中华绒螯蟹进行了遗传分析。gambiae复合体的研究揭示了第三种paraminase的存在（68-78%的同一性），我们将其命名为AgAcp 34 A-3。FISH分析表明，该基因定位在染色体3R的同一分裂（34 A）的其他两个旁系同源。特别是，针对AgAcp 34 A-2和AgAcp 34 A-3的C-末端的免疫荧光测定显示，这两种蛋白质位于MAG的后部，并集中在交配栓的顶端部分。当转移到女性，这部分的塞子位于连接受精囊到子宫的管道附近，这表明这些蛋白质在调节精子活力的潜在作用。AgAcp 34 A-3比其他两个旁系同源物更具有多态性，这可能是因为纯化选择的放松。由于不平等的交换和基因转换可能使这个基因家族的成员同质化，因此对进化模式的解释并不简单。虽然这三个旁系同源物的几个单倍型是大多数A.冈比亚有限公司种，也观察到一些固定的种特异性替换（主要放置在N-和C-末端部分的分泌肽），这表明一些谱系特异性适应。结论：对A.冈比亚生殖途径的研究将阐明这种MAG特异性蛋白家族与其雌性对应物的相互作用。这些知识将有助于更好地评估与A.冈比亚物种，可以帮助解释观察到的进化模式。
Background: During copulation, the major Afro-tropical malaria vector Anopheles gambiae s.s. transfers male accessory gland (MAG) proteins to females as a solid mass (i.e. the "mating plug"). These proteins are postulated to function as important modulators of female post-mating responses. To understand the role of selective forces underlying the evolution of these proteins in the A. gambiae complex, we carried out an evolutionary analysis of gene sequence and expression divergence on a pair of paralog genes called AgAcp34A-1 and AgAcp34A-2. These encode MAG-specific proteins which, based on homology with Drosophila, have been hypothesized to play a role in sperm viability and function. Results: Genetic analysis of 6 species of the A. gambiae complex revealed the existence of a third paralog (68-78% of identity), that we named AgAcp34A-3. FISH assays showed that this gene maps in the same division (34A) of chromosome-3R as the other two paralogs. In particular, immuno-fluorescence assays targeting the C-terminals of AgAcp34A-2 and AgAcp34A-3 revealed that these two proteins are localized in the posterior part of the MAG and concentrated at the apical portion of the mating plug. When transferred to females, this part of the plug lies in proximity to the duct connecting the spermatheca to the uterus, suggesting a potential role for these proteins in regulating sperm motility. AgAcp34A-3 is more polymorphic than the other two paralogs, possibly because of relaxation of purifying selection. Since both unequal crossing-over and gene conversion likely homogenized the members of this gene family, the interpretation of the evolutionary patterns is not straightforward. Although several haplotypes of the three paralogs are shared by most A. gambiae s.l. species, some fixed species-specific replacements (mainly placed in the N- and C-terminal portions of the secreted peptides) were also observed, suggesting some lineage-specific adaptation. Conclusions: Progress in understanding the signaling cascade in the A. gambiae reproductive pathway will elucidate the interaction of this MAG-specific protein family with their female counterparts. This knowledge will allow a better evaluation of the relative importance of genes involved in the reproductive isolation and fertility of A. gambiae species and could help the interpretation of the observed evolutionary patterns.