Thompson Fiona J, Barker Gary L A, Hughes Louise, Wilkes Clare P, Coghill Jane, Viney Mark E
School of Biological Sciences, University of Bristol, Woodland Road, Bristol, BS8 1UG, UK.
BMC Genomics. 2006 Jun 19;7:157. doi: 10.1186/1471-2164-7-157.
The nematode Strongyloides ratti has two adult phases in its lifecycle: one obligate, female and parasitic and one facultative, dioecious and free-living. The molecular control of the development of this free-living generation remains to be elucidated.
We have constructed an S. ratti cDNA microarray and used it to interrogate changes in gene expression during the free-living phase of the S. ratti life-cycle. We have found very extensive differences in gene expression between first-stage larvae (L1) passed in faeces and infective L3s preparing to infect hosts. In L1 stages there was comparatively greater expression of genes involved in growth. We have also compared gene expression in L2 stages destined to develop directly into infective L3s with those destined to develop indirectly into free-living adults. This revealed relatively small differences in gene expression. We find little evidence for the conservation of transcription profiles between S. ratti and S. stercoralis or C. elegans.
This is the first multi-gene study of gene expression in S. ratti. This has shown that robust data can be generated, with consistent measures of expression within computationally determined clusters and contigs. We find inconsistencies between EST representation data and microarray hybridization data in the identification of genes with stage-specific expression and highly expressed genes. Many of the genes whose expression is significantly different between L1 and iL3s stages are unknown beyond alignments to predicted genes. This highlights the forthcoming challenge in actually determining the role of these genes in the life of S. ratti.
鼠类圆线虫在其生命周期中有两个成虫阶段：一个是专性的、雌性且寄生的阶段，另一个是兼性的、雌雄异体且自由生活的阶段。这种自由生活世代发育的分子调控机制仍有待阐明。
我们构建了鼠类圆线虫的cDNA微阵列，并利用它来研究鼠类圆线虫生命周期中自由生活阶段的基因表达变化。我们发现，粪便中排出的第一期幼虫（L1）与准备感染宿主的感染性L3之间，基因表达存在非常广泛的差异。在L1阶段，参与生长的基因表达相对较高。我们还比较了直接发育为感染性L3的L2阶段与间接发育为自由生活成虫的L2阶段的基因表达。这揭示了基因表达的相对较小差异。我们几乎没有发现鼠类圆线虫与粪类圆线虫或秀丽隐杆线虫之间转录谱保守性的证据。
这是对鼠类圆线虫基因表达的首次多基因研究。研究表明，可以生成可靠的数据，在通过计算确定的簇和重叠群内有一致的表达量度。我们发现在鉴定具有阶段特异性表达的基因和高表达基因时，EST代表性数据与微阵列杂交数据之间存在不一致。在L1和感染性L3阶段之间表达有显著差异的许多基因，除了与预测基因的比对之外，其功能尚不清楚。这突出了实际确定这些基因在鼠类圆线虫生命中的作用所面临的挑战。
