The Chlamydomonas reinhardtii cell wall is made up of hydroxyproline-rich glycoproteins, arranged in five distinct layers. The W6 (crystalline) layer contains three major glycoproteins (GP1, GP2, GP3), selectively extractable with chaotropic agents, that self-assemble into crystals in vitro. A system to study W6 assembly in a quantitative fashion was developed that employs perchlorate-extracted...

A cold-inducible transposon called Jordan has previously been used to tag and recover genes controlling key aspects of Volvox development, including the process called inversion. In a search for additional genes, we isolated 17 new inversionless mutants from cultures grown at 24 degrees (the temperature that activates Jordan transposition). These mutants were stable at 32 degrees, but generated...

Epigenetic silencing of foreign genes introduced into plants poses an unsolved problem for transgenic technology. Here we have used the simple multicellular green alga VOLVOX: carteri as a model to analyse the relation of DNA methylation to transgenic silencing. VOLVOX: DNA contains on average 1.1% 5-methylcytosine and 0.3% N6-methyladenine, as revealed by electrospray mass spectrometry and pho...

The alga Volvox carteri is one of the simplest multicellular organisms, yet it has a surprisingly complex extracellular matrix (ECM), making Volvox suitable as a model system in which to study ECM self-assembly. Here, we analyze the primary structures and post-translational modifications of two main ECM components synthesized in response to sexual induction as well as wounding. These proteins a...

To understand the hierarchy of life in evolutionary terms, we must explain why groups of one kind of individual, say cells, evolve into a new higher level individual, a multicellular organism. A fundamental step in this process is the division of labor into nonreproductive altruistic soma. The regA gene is critical for somatic differentiation in Volvox carteri, a multicellular species of volvoc...

In Volvox carteri development, visibly asymmetric cleavage divisions set apart large embryonic cells that will become asexual reproductive cells (gonidia) from smaller cells that will produce terminally differentiated somatic cells. Three mechanisms have been proposed to explain how asymmetric division leads to cell specification in Volvox: (a) by a direct effect of cell size (or a property der...

The sulphated glycoprotein SSG 185 is the monomeric precursor of a highly aggregated structural element in the extracellular matrix of the multicellular green alga Volvox carteri. A phosphodiester of arabinose was isolated from a saccharide fragment of SSG 185. The structure of this phosphodiester was investigated by methylation analysis, 13C-NMR, photometric methods and enzymatic assays and id...