Is the frequency of apomeiosis in the Rhodophyta a genetic character?
The small rhodophyte Antithamnionella sarniensis Lyle (Ceramiaceae), a very common species on the Atlantic coast of France, has a normal Polysiphonia-like life cycle (Sundene, 1964), but some tetraspores can give new tetrasporophytes directly (L'Hardy-Halos, 1985). This phenomenon has now been studied in detail (Magne, 1986). Twenty strains were prepared starting from sterile plants collected in various places along three hundred kilometers of shoreline. The strains were kept in stock cultures at a low temperature (14 C) with dim natural light and were propagated only by cutting. Exceptionally, one of these strains originated from an apomeiotic tetraspore, and another one is the original strain of von Stosch (1969), who kindly provided it. All the strains proved to be tetrasporophytic, in accordance with the dominance of tetrasporophytes in the field. The progenies of the different strains have been investigated. For each, material from the stock culture was cultivated in monitored conditions (20°C with cool white light of 20 tE.-m-2.s 1, 12 h.d ') to produce tetraspores. Plantlets issuing from the spore-sets were picked randomly, individually transferred in small glass jars and cultivated until reproductive organs were formed; one hundred plantlets were used of each strain. In numerous strains, the progeny is a mixture of gametophytes and tetrasporophytes; the proportions of tetrasporophytes differ from one strain to another over a range from 0% to 100% and show many intermediate values (Magne, 1986). It can be sup-
POSSIBILITE D'UNE CULTURE INDUSTRIELLE DE L'ALGUE ROUGE EUCHEUMA SPINOSUM DANS LE GOLFE DE TADJOURAH 'l'
L'algue rouge Eucheuma spinosum (fig. 1) contient en forte proportion un produit de tres haute qualite et relativement rare : le iota carraghenane. Ce compose est isole par les usines d'extraction et utilise, une fois purifie, dans de nombreuses branches industrielles, notamment dans l'industrie alimentaire pour la constitution de la plupart des flans, laits gelifies, glaces, pâtisseries, etc ...
The enzymic hydrolysis of carrageenin.
Carrageenin is the water soluble polysaccharide extractable from the red algae Chondrus crispus and Gigartina stellata. The polysaccharide is essentially a polymer of alpha-D-galactopyranoside-4-sulphate. Smith et al. (1954) fractionated carrageenin with potassium chloride into two components and obtained a precipitable component which could form gels and a nongelling component which remained in solution. The former was designated kappa-carrageenin and the latter lambda-carrageenin. Smith, O'Neill, Perlin, and Cook (personal communication) found that these fractions differ in their content of D-anhydrogalactose. Mori (1943a) demonstrated a hydrolase in marine molluscs which degraded the mucilage from Chondrus ocellatus. The bacterial decomposition of carrageenin has been commonly recognized but this has not been related to any particular organism or enzyme. The purpose of the work to be described was to attempt to isolate and characterize a bacterial carrageenase.