Maside Xulio, Gómez-Moracho Tamara, Jara Laura, Martín-Hernández Raquel, De la Rúa Pilar, Higes Mariano, Bartolomé Carolina
Medicina Xenómica, CIMUS, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain.
Xenómica Comparada de Parásitos Humanos, IDIS, Santiago de Compostela, Galicia, Spain.
PLoS One. 2015 Dec 31;10(12):e0145609. doi: 10.1371/journal.pone.0145609. eCollection 2015.
Two microsporidians are known to infect honey bees: Nosema apis and Nosema ceranae. Whereas population genetics data for the latter have been released in the last few years, such information is still missing for N. apis. Here we analyze the patterns of nucleotide polymorphism at three single-copy loci (PTP2, PTP3 and RPB1) in a collection of Apis mellifera isolates from all over the world, naturally infected either with N. apis (N = 22) or N. ceranae (N = 23), to provide new insights into the genetic diversity, demography and evolution of N. apis, as well as to compare them with evidence from N. ceranae. Neutral variation in N. apis and N. ceranae is of the order of 1%. This amount of diversity suggests that there is no substantial differentiation between the genetic content of the two nuclei present in these parasites, and evidence for genetic recombination provides a putative mechanism for the flow of genetic information between chromosomes. The analysis of the frequency spectrum of neutral variants reveals a significant surplus of low frequency variants, particularly in N. ceranae, and suggests that the populations of the two pathogens are not in mutation-drift equilibrium and that they have experienced a population expansion. Most of the variation in both species occurs within honey bee colonies (between 62%-90% of the total genetic variance), although in N. apis there is evidence for differentiation between parasites isolated from distinct A. mellifera lineages (20%-34% of the total variance), specifically between those collected from lineages A and C (or M). This scenario is consistent with a long-term host-parasite relationship and contrasts with the lack of differentiation observed among host-lineages in N. ceranae (< 4% of the variance), which suggests that the spread of this emergent pathogen throughout the A. mellifera worldwide population is a recent event.
蜜蜂微孢子虫（Nosema apis）和东方蜜蜂微孢子虫（Nosema ceranae）。尽管近年来已公布了关于后者的群体遗传学数据，但关于蜜蜂微孢子虫的此类信息仍然缺失。在此，我们分析了来自世界各地的意大利蜜蜂（Apis mellifera）分离株中三个单拷贝基因座（PTP2、PTP3和RPB1）的核苷酸多态性模式，这些分离株自然感染了蜜蜂微孢子虫（N = 22）或东方蜜蜂微孢子虫（N = 23），以便为蜜蜂微孢子虫的遗传多样性、种群统计学和进化提供新的见解，并将它们与来自东方蜜蜂微孢子虫的证据进行比较。蜜蜂微孢子虫和东方蜜蜂微孢子虫的中性变异约为1%。这种多样性水平表明，这些寄生虫中存在的两个细胞核的遗传内容之间没有实质性差异，并且遗传重组的证据为染色体之间的遗传信息流动提供了一种推定机制。对中性变异频率谱的分析揭示了低频变异的显著过剩，特别是在东方蜜蜂微孢子虫中，并表明这两种病原体的种群并非处于突变 - 漂变平衡状态，且它们经历了种群扩张。两种微孢子虫的大多数变异都发生在蜂群内部（占总遗传方差的62% - 90%），尽管在蜜蜂微孢子虫中，有证据表明从不同意大利蜜蜂品系分离的寄生虫之间存在分化（占总方差的20% - 34%），特别是从A品系和C品系（或M品系）收集的寄生虫之间。这种情况与长期的宿主 - 寄生虫关系一致，并且与在东方蜜蜂微孢子虫中观察到的宿主品系之间缺乏分化形成对比（<4%的方差），这表明这种新兴病原体在全球意大利蜜蜂种群中的传播是最近才发生的事件。
