The study of the dependence of reactions on the concentration of various compounds is often of great value in determining reaction mechanisms . In chemical kinetics, it is often found that, according to van't Hoff's rule, the order of dependence of a reaction on the concentration of some compound involved in that reaction is equal to the number of molecules of the compound involved in each reac...

A method is described for the isolation and purification of the sexual inducer produced by male colonies of the colonial green alga Volvox carteri. The procedure yields a highly purified preparation of the inducer. The biologically active principal is demonstrated to be a glycoprotein with a molecular weight of 32,000.

Flagella-generated fluid stirring has been suggested to enhance nutrient uptake for sufficiently large micro-organisms, and to have played a role in evolutionary transitions to multicellularity. A corollary to this predicted size-dependent benefit is a propensity for phenotypic plasticity in the flow-generating mechanism to appear in large species under nutrient deprivation. We examined four sp...

Volvox is a very interesting oogamous organism that exhibits various types of sexuality and/or sexual spheroids depending upon species or strains. However, molecular bases of such sexual reproduction characteristics have not been studied in this genus. In the model species V. carteri, an ortholog of the minus mating type-determining or minus dominance gene (MID) of isogamous Chlamydomonas reinh...

BACKGROUND Bacteria of the family Rickettsiaceae are principally associated with arthropods. Recently, endosymbionts of the Rickettsiaceae have been found in non-phagotrophic cells of the volvocalean green algae Carteria cerasiformis, Pleodorina japonica, and Volvox carteri. Such endosymbionts were present in only C. cerasiformis strain NIES-425 and V. carteri strain UTEX 2180, of various strai...

Male and female sexes have evolved repeatedly in eukaryotes but the origins of dimorphic sexes and their relationship to mating types in unicellular species are not understood. Volvocine algae include isogamous species such as Chlamydomonas reinhardtii, with two equal-sized mating types, and oogamous multicellular species such as Volvox carteri with sperm-producing males and egg-producing femal...

Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute (∼0.3%) density excess of V. carteri ove...