454 pyroqsequencing of 16S v4 amplicons from dichorionic triplet fecal samples.. Dichorionic 454

Monozygotic and dizygotic twin studies investigating the relative roles of host genetics and environmental factors in shaping gut microbiota composition have produced conflicting results. In this study, we investigated the gut microbiota composition in a healthy dichorionic triplet set. Dichorionic triplet sets contain a pair of monozygotic twins and a naturally occurring control, the fraternal triplet, with similar pre- and post-natal environmental conditions. V4 16S rRNA pyrosequencing was employed to investigate microbiota composition, and the species and strain diversity of the culturable bifidobacterial population was also examined. At month 1, the gut microbiota of all infants was dominated by bifidobacteria, with the monozygotic pair sharing a similar microbiota compared to their fraternal sibling. This colonisation pattern was similar at months 2 and 3; however by month 12, there was no greater similarity observed in the microbiota profile of the monozygotic pair compared to the fraternal sibling. Principal Coordinate Analyses (PCoA) plots of the microbiota composition at month 12 appeared equally dissimilar amongst all three. The microbiota of two antibiotic-treated dichorionic triplet sets was also investigated. Not surprisingly, in both cases early life antibiotic administration appeared to be the major overriding determinant of microbiota composition at month 1, irrespective of zygosity. By month 12, early antibiotic administration appeared to no longer influence the gut microbiota composition. We hypothesize that initially host genetics play a significant role in the composition of an individual’s gut microbiota unless an antibiotic intervention is given, but by month 12 environmental factors are the major determinant.

针对宿主遗传与环境因素在塑造肠道菌群（gut microbiota）组成中相对作用的同卵双生子（monozygotic）与异卵双生子（dizygotic）研究，所得结论始终存在分歧。本研究针对一组健康的双绒毛膜（dichorionic）三胞胎开展肠道菌群组成分析。双绒毛膜三胞胎组包含一对同卵双生子，以及一个天然对照——异卵三胞胎个体，二者产前与产后环境条件基本一致。本研究采用V4区16S rRNA焦磷酸测序（pyrosequencing）分析菌群组成，同时对可培养双歧杆菌（Bifidobacterium）种群的物种与菌株多样性进行了检测。出生后第1个月时，所有受试婴儿的肠道菌群均以双歧杆菌占优，且同卵双生子的菌群组成相较于其异卵同胞更为相似。该定植模式在第2、3个月时保持一致；但至第12个月时，同卵双生子的菌群特征相较于异卵同胞已无显著相似性。对第12个月的肠道菌群组成进行主坐标分析（Principal Coordinate Analyses, PCoA）的结果显示，三名个体的菌群特征均呈现相近程度的差异。本研究同时对两组经抗生素干预的双绒毛膜三胞胎的肠道菌群展开分析。不出所料，两组受试对象在出生早期的抗生素使用均成为第1个月肠道菌群组成的主导决定因素，与合子性（zygosity）无关。至第12个月时，出生早期的抗生素干预已不再对肠道菌群组成产生显著影响。本研究提出如下假说：宿主遗传因素在个体肠道菌群组成建立初期发挥关键作用，但若此时施加抗生素干预则例外；而至第12个月时，环境因素已成为肠道菌群组成的主要决定因素。