Recent studies reveal that relationships among the volvocine algae are more complex than was previously believed. Nevertheless, this group still appears to provide an unrivaled opportunity to analyze an evolutionary pathway leading from unicellularity (Chlamydomonas) to multicellularity with division of labor (Volvox). Significant progress in this regard was made in the past year when two genes...

We have isolated a 1595-bp transposable element from the multicellular green alga Volvox carteri following its insertion into the nitrate reductase (nitA) locus. This element, which we have named Jordan, has short (12-bp) terminal inverted repeats and creates a 3-bp target site duplication, like some higher plant transposons of the classic type. Contained within the first 200 bp of one end of t...

Phytoplankton constitutes the primary producers of aquatic ecosystems and represents the food chain base that supports the commercial fisheries of most water bodies. Nowadays, there is lack of information on phytoplankton assemblages of most reservoirs in Africa. To contribute with this knowledge, this study was carried out to determine the density and diversity of seasonal variations of phytop...

The reproduction and the formation of resistant dormant spores in Volvox aureus Ehr. and V. tertius Meyer were studied in a temporary pool during July–August 1996 and 1997. It has been shown that the populations of two species of Volvox (L.) Ehr. from this pool were characterized by different reproductive traits. Comparatively small quantity of male individuals and dormant zygotes (zygospores) ...

The coordinated movements of epithelial tissues play vital roles in a variety of processes, from embryonic development to wound healing. The multicellular green alga Volvox carteri is a useful model organism for studying one such movement: epithelial bending [2]. During embryogenesis, the immature spheroid Volvox undergoes a process known as inversion whereby it turns itself completely inside o...

In the preceding paper [l] a model was proposed which offers an explanation to many aspects of embryogenesis in volvox. In particular, the model explains pattern formation during embryogenesis, i.e., it correctly predicts the very regular positioning of the reproductive cells (gonidia) within the Volvox spheroids. The assumption was made that membrane proteins mediating cell-cell contacts are i...

glsA gene product, which is required for asymmetric division, and the regA gene product, which is required for terminal differentiation of somatic cells. More recently, they have also been used to show that the invA gene encodes a novel kinesin that drives inversion. What can Volvox tell us about the evolutionary origins of multicellularity and cellular differentiation? The family Volvocaceae, ...