Zolnik Christine P, Prill Robert J, Falco Richard C, Daniels Thomas J, Kolokotronis Sergios-Orestis
Department of Biological Sciences, Fordham University, 441 East Fordham Road, Bronx, NY, 10458, USA.
Vector Ecology Laboratory, Louis Calder Center-Biological Field Station, Fordham University, 53 Whippoorwill Road, Armonk, NY, 10504, USA.
Mol Ecol. 2016 Oct;25(19):4963-77. doi: 10.1111/mec.13832. Epub 2016 Sep 18.
Blacklegged ticks (Ixodes scapularis) are one of the most important pathogen vectors in the United States, responsible for transmitting Lyme disease and other tick-borne diseases. The structure of a host's microbial community has the potential to affect the ecology and evolution of the host. We employed high-throughput sequencing of the 16S rRNA gene V3-V4 hypervariable regions in the first study to investigate the tick microbiome across all developmental stages (larvae, nymphs, adults). In addition to field-collected life stages, newly hatched laboratory-reared larvae were studied to determine the baseline microbial community structure and to assess transovarial transmission. We also targeted midguts and salivary glands due to their importance in pathogen maintenance and transmission. Over 100 000 sequences were produced per life stage replicate. Rickettsia was the most abundant bacterial genus across all sample types matching mostly the Ixodes rickettsial endosymbionts, and its proportion decreased as developmental stage progressed, with the exception of adult females that harboured a mean relative abundance of 97.9%. Laboratory-reared larvae displayed the lowest bacterial diversity, containing almost exclusively Rickettsia. Many of the remaining bacteria included genera associated with soil, water and plants, suggesting environmental acquisition while off-host. Female organs exhibited significantly different β-diversity than the whole tick from which they were derived. Our results demonstrate clear differences in both α- and β-diversity among tick developmental stages and between tick organs and the tick as a whole. Furthermore, field-acquired bacteria appear to be very important to the overall internal bacterial community of this tick species, with influence from the host bloodmeal appearing limited.
黑脚蜱（肩突硬蜱）是美国最重要的病原体传播媒介之一，负责传播莱姆病和其他蜱传疾病。宿主微生物群落的结构有可能影响宿主的生态和进化。在第一项研究中，我们采用16S rRNA基因V3 - V4高变区的高通量测序来研究蜱在所有发育阶段（幼虫、若虫、成虫）的微生物组。除了野外采集的各个生命阶段的蜱，还研究了新孵化的实验室饲养的幼虫，以确定基线微生物群落结构并评估经卵传播。由于中肠和唾液腺在病原体维持和传播中的重要性，我们也将其作为研究目标。每个生命阶段的重复样本产生了超过100000条序列。立克次氏体是所有样本类型中最丰富的细菌属，大多与肩突硬蜱立克次氏体共生菌匹配，其比例随着发育阶段的推进而降低，但成年雌性蜱除外，其平均相对丰度为97.9%。实验室饲养的幼虫细菌多样性最低，几乎只含有立克次氏体。其余许多细菌包括与土壤、水和植物相关的属，表明在脱离宿主时从环境中获取。雌性器官的β多样性与它们所来源的整个蜱显著不同。我们的结果表明，蜱的发育阶段之间以及蜱器官与整个蜱之间在α多样性和β多样性上都存在明显差异。此外，野外获取的细菌似乎对这种蜱的整体内部细菌群落非常重要，而宿主血餐的影响似乎有限。
