DBG · Promoting young researchers

Eva Laura von der Heyde

Light microscopy image of the multicellular green alga Volvox carteri during embryonic cell divisions (left) and in the adult stage (right). The spherical organism has two different cell types. There are about 2000 small, somatic cells at the surface of the spheroid, which have simple eyes and two flagella for locomotion. The individual somatic cells are probably similar to the unicellular ancestors of the Volvocales. The significantly larger, reproductive cells are located within the spheroid and perform a series of cell divisions to become the daughter spheroids of the next generation. Photo: Eva L. von der Heyde

Eva Laura von der Heyde's work was awarded with the Prize for the Best Plant Science Master Thesis, which was carried out at Bielefeld University in the year 2015.

Title of the awarded thesis

"Study of taxonomically restricted gene families in Volvox carteri"

She identified and analysed those gene families in the multicellular green algae Volvox carteri that developed during evolution from unicellular to multicellular organisms. These gene families could be crucial for evolution of multicellularity.

The evolution of multicellularity and the division of labor between different cell types probably required both the alteration of existing genes and the development of novel genes from previously noncoding sequences.

By comparing the genome of the multicellular green algae Volvox carteri with the genome of its unicellular relative Chlamydomonas reinhardtii both potential novel and heavily modified genes could be identified. Some of these genes, which show no similarity to genes from Chlamydomonas or other unicellular algae species, were investigated at the genomic and transcriptional level. Furthermore, a new chimeric gene construct was established for use in Volvox carteri. This construct allows further investigations and consists of the inducible nitrate reductase promoter and a bioluminescent reporter gene, namely the gene of the luciferase from Gaussia princeps.

The results of this work have shown that the group of potentially Volvox-specific genes, which was originally identified as part of the Volvox genome project, is a diverse collection of genes of different ages, origins, functions and taxonomic distributions. The data suggest that some of the examined genes might be specific for multicellular Volvocales. The proof of gene expression and the existence of a relatively long open reading frame show that the genes are no artifacts of gene prediction. Thus, promising candidates for subsequent studies could be identified. Future investigations will show whether these gene families were involved in the development of characteristic features of this lineage and which role they might have played in the development of multicellularity, oogamy or cellular differentiation.

Parts of the work are published in

von der Heyde, E. L., Klein, B., Abram, L., & Hallmann, A. (2015). The inducible nitA promoter provides a powerful molecular switch for transgene expression in Volvox carteri. BMC Biotechnology, 15(1), 5.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4339647/">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4339647/

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Eva Laura von der Heyde conducted this work in the Department for Cellular and Developmental Biology of Plants in the working group of Prof. Dr. Armin Hallmann.

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