Cell-type specific light-mediated transcript regulation in the multicellular alga Volvox carteri.

Arash Kianianmomeni

doi:10.1186/1471-2164-15-764

Abstract

BackgroundThe multicellular green alga Volvox carteri makes use of none less than 13 photoreceptors, which are mostly expressed in a cell-type specific manner. This gives reason to believe that trasncriptome pattern of each cell type could change differentially in response to environmental light. Here, the cell-type specific changes of various transcripts from different pathways in response to blue, red and far-red light were analyzed.ResultsIn response to different light qualities, distinct changes in transcript accumulation of genes encoding proteins involved in chlorophyll and carotenoid biosynthesis, light-harvesting complexes, circadian clock and cell cycle control were observed. Namely, blue light tends to be effective to accumulate transcripts in the somatic cells; while red light leads to accumulate transcripts predominantly in the reproductive cells. Blue light also induced marked accumulation of two components of circadian rhythms only in the somatic cells, indicating that these clock-relevant components are affected by blue light in a cell-type specific manner. Further, we show that photosynthetic associated genes are regulated distinctly among cell types by different light qualities.ConclusionOur results suggest that Volvox uses different sophisticated cell-type specific light signaling pathways to modulate expression of genes involved in various cellular and metabolic pathways including circadian rhythms and photosynthesis in response to environmental light.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-764) contains supplementary material, which is available to authorized users.

Highlights

The multicellular green alga Volvox carteri makes use of none less than 13 photoreceptors, which are mostly expressed in a cell-type specific manner
In addition to the previous studies which showed that VR1 and channelrhodopsins are highly expressed in the reproductive and somatic cells, respectively [19,20], recent investigations revealed that most photoreceptors are expressed in a cell-type specific manner [6,16] (Figure 1)
Because the cell-type specific transcript level of photoreceptors depends on the developmental stages, we analyzed their transcript levels right after separation of cell types, i.e. three hours before initiation of cleavage division, and at the end of dark incubation step (Additional file 1: Figure S1A-B)

Summary

Introduction

The multicellular green alga Volvox carteri makes use of none less than 13 photoreceptors, which are mostly expressed in a cell-type specific manner This gives reason to believe that trasncriptome pattern of each cell type could change differentially in response to environmental light. The cell-type specific changes of various transcripts from different pathways in response to blue, red and far-red light were analyzed The photosynthetic organisms such as free swimming microalgae use light signals to modulate a wide variety of physiological and cellular responses including sexual life cycle, circadian clock, cellular differentiation, cell cycle, nitrogen and lipid metabolism [1,2,3,4]. Volvox is one of the simplest multicellular organisms composed of only two cell types, 2000–4000 biflagellate motile, terminally differentiated somatic cells, which build a monolayer at the surface of a spheroid, and around 16

Methods

Results

Conclusion