Transcriptome profiling of individual larvae of two different developmental modes in the poecilogonous polychaeteStreblospio benedicti (Spionidae)

Abstract

Understanding the range of biochemical and physiological phenotypes in a cohort of embryos or larvae is crucial to understanding the lifespan, dispersal potential, and recruitment success of the early life history stages of a species. In this study, a novel kinetic assay has been employed to profile the transcriptome pool complexity in individual larvae of both planktotrophic and lecithotrophic developmental modes in the poecilogonous polycheate Streblospio benedicti. Using a nano-scale synthesis strategy, the mRNA pool in a single embryo or larva can be amplified into cDNA for quantitative characterization in a high-throughput, kinetic reannealing assay in a 96-well, microtiterplate format. This assay generates transcript-pool complexity estimates at 1 degrees C temperature increments for each sample producing 3,360 quantitative measurements per 96-well plate. Measuring transcriptome complexity on 8 individual planktotrophic and 8 individual lecithotrophic larvae (with 4 duplicate assays for each individual) reveals a more complex gene expression profile in planktotrophic larvae and a lower level of interindividual variation in expression patterns in lecithotrophic larvae. Although differences in these gene expression patterns are more likely due to physiological differences between feeding and non-feeding larval types in these late-stage individuals, this is one of the first assessments of inter-individual variation in gene expression patterns in marine invertebrate larvae and indicates a large potential for developmental variability.

Genomics-enabled research in marine ecology: challenges, risks and pay-offs

“…a collection of all mRNAs in a cell) as a means to focus the article, illustrate the power of this approach, and to highlight the advances made using techniques that profile patterns of gene expression (Schena et al 1995, Gracey & Cossins 2003, Allison et al 2006. It should be noted that there are numerous other examples within marine ecological genomics (Venter et al 2004), and other important analytical tools (Marsh & Fielman 2005). Broadly focused discussions of genomics specific to ecological interests can be found in van Straalen et al (2006) and recent reviews (Gibson 2002, Thomas & Klaper 2004).…”

Developmental plasticity and the evolution of animal complex life cycles

“…Data from suitably chosen taxa are not yet available, but relevant information is emerging from studies of life cycle transcriptomes of holometabolous insects (Drosophila melanogaster, Arbeitman et al 2002; Anopheles gambiae, Koutsos et al 2007), as well as from comparisons of transcriptome dynamics between alternative phenotypes in polyphenic nematodes (normal versus dauer larva in C. elegans ;Holt 2006) or between alternative larval types normally expressed by poecilogonous animals (planktotrophic versus lecithotrophic larvae of the polychaete Streblospio benedicti; Marsh & Fielman 2005).…”

“…Interestingly, results of two studies (dealing admittedly, with very different organisms rather than with two directly comparable taxa) converge in singling out the earliest post-embryonic stages as a segment of developmental history which is particularly prone to polyphenism or to diverge from later stages through changes in transcription profiles that probably correspond to (i) changes in the activity of genes for transcription factors (early versus late larvae in Anopheles; Koutsos et al 2007) and (ii) increasingly strict control of transcription in what is likely the more derived phenotype (lecithotrophic larvae of poecilogonous polychaetes; Marsh & Fielman 2005).…”

Environmental and Molecular Mechanisms of Cold Adaptation in Polar Marine Invertebrates

“…However, methodological advances have allowed for quantitative measurements of molecular and physiological rate processes at the level of individual larvae in terms metabolic rates (Szela and Marsh, 2005), enzyme activities (Marsh et al, 2001a), and transcriptome profi ling (Marsh and Fielman, 2005). We are now beginning to understand the ecological importance of assessing the phenotypic variance of characteristics likely experiencing high selective pressures.…”

“…In order to compare changes within embryos or larvae to changes in gene activities, a novel methodology based on reannealing kinetics is employed for the rapid, high-throughput, effi cient, and economical profi ling of the sequence complexity of a transcriptome (Marsh and Fielman, 2005;Hoover et al, 2007a;. Measuring renaturation rates of cDNA along a temperature gradient can provide information about the transcript sequence complexity of a nucleic acid pool sample.…”