Soulmaz Ekhtari - Department of Plant Biology, Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
Karim Hasanpur - Department of Animal Science- Faculty of Agriculture, University of Tabriz, Tabriz, Iran
Jafar Razeghi - Department of Plant Biology- Faculty of Natural Sciences, University of Tabriz, Tabriz, Iran
Arash Kianianmomeni - Department of Cellular and Developmental Biology of Plants, Faculty of Natural Sciences, University of Bielefeld, Bielefeld, Germany

The evolutionary origin of some of the multicellular organisms is not yet comprehensively studied. Germ-soma differentiation is an obvious characteristic of complex multicellular organisms. The multicellular green alga, Volvox carteri composed of only 2000–4000 terminally differentiated somatic cells, which build a monolayer at the surface of a spheroid, and around 16 much larger reproductive cells within the surface. Finding out how unicellular organisms can develop in to multicellular organisms over the course of evolution is a central issue in biological research. V. carteri is a simple organism which provides a unique opportunity to study the molecular mechanisms of transmission from unicellularity to multicellularity and to discover universal rules of cellular differentiation in eukaryote. Here, the RNA-seq approach was employed to investigate transcriptome profiling of two separated cell types of V. carteri. Our results revealed that,almost half of the V. carteri genes (11783 genes out of 21000 genes) were differentially expressed between the two cell-types. This strongly suggested different functions for genes of each cell type and demonstrated a more complex process of differentiation. Almost 30% of differentially expressed genes were from loci without any annotation and can be considered as novel genes that need to be identified. Therefore, a comprehensive comparative analysis is required to identify the determined cell type function of each differentially expressed gene and to solve their rules in differentiation process.

Cell types, Cellular differentiation, Volvox carteri, RNA-seq, Transcriptomics