Cornman R Scott, Chen Yan Ping, Schatz Michael C, Street Craig, Zhao Yan, Desany Brian, Egholm Michael, Hutchison Stephen, Pettis Jeffery S, Lipkin W Ian, Evans Jay D
USDA-ARS Bee Research Lab, Beltsville, Maryland, United States of America.
PLoS Pathog. 2009 Jun;5(6):e1000466. doi: 10.1371/journal.ppat.1000466. Epub 2009 Jun 5.
Recent steep declines in honey bee health have severely impacted the beekeeping industry, presenting new risks for agricultural commodities that depend on insect pollination. Honey bee declines could reflect increased pressures from parasites and pathogens. The incidence of the microsporidian pathogen Nosema ceranae has increased significantly in the past decade. Here we present a draft assembly (7.86 MB) of the N. ceranae genome derived from pyrosequence data, including initial gene models and genomic comparisons with other members of this highly derived fungal lineage. N. ceranae has a strongly AT-biased genome (74% A+T) and a diversity of repetitive elements, complicating the assembly. Of 2,614 predicted protein-coding sequences, we conservatively estimate that 1,366 have homologs in the microsporidian Encephalitozoon cuniculi, the most closely related published genome sequence. We identify genes conserved among microsporidia that lack clear homology outside this group, which are of special interest as potential virulence factors in this group of obligate parasites. A substantial fraction of the diminutive N. ceranae proteome consists of novel and transposable-element proteins. For a majority of well-supported gene models, a conserved sense-strand motif can be found within 15 bases upstream of the start codon; a previously uncharacterized version of this motif is also present in E. cuniculi. These comparisons provide insight into the architecture, regulation, and evolution of microsporidian genomes, and will drive investigations into honey bee-Nosema interactions.
近期蜜蜂健康状况的急剧下降严重影响了养蜂业，给依赖昆虫授粉的农产品带来了新的风险。蜜蜂数量的减少可能反映出寄生虫和病原体带来的压力增加。在过去十年中，微孢子虫病原体蜜蜂微孢子虫（Nosema ceranae）的发病率显著上升。在此，我们展示了一份基于焦磷酸测序数据组装的蜜蜂微孢子虫基因组草图（7.86 MB），包括初步的基因模型以及与这个高度特化的真菌谱系其他成员的基因组比较。蜜蜂微孢子虫具有强烈的AT偏向性基因组（74% A+T）和多种重复元件，这使得组装工作变得复杂。在2614个预测的蛋白质编码序列中，我们保守估计有1366个在微孢子虫恩氏蜂孢子虫（Encephalitozoon cuniculi）中有同源物，恩氏蜂孢子虫是已发表的最密切相关的基因组序列。我们鉴定出在微孢子虫中保守但在该类群之外缺乏明确同源性的基因，这些基因作为这组专性寄生虫中的潜在毒力因子特别受关注。微小的蜜蜂微孢子虫蛋白质组中有很大一部分由新的和转座元件蛋白组成。对于大多数有充分支持的基因模型，在起始密码子上游15个碱基内可以找到一个保守的有义链基序；恩氏蜂孢子虫中也存在这个基序的一个以前未被表征的版本。这些比较为微孢子虫基因组的结构、调控和进化提供了见解，并将推动对蜜蜂 - 蜜蜂微孢子虫相互作用的研究。
