The alpha-tubulin genes from two psychrophilic algae belonging to the genus Chloromonas (here named ANT1 and ANT3) have been isolated and sequenced. The genes ant1 and ant3 contain 4 and 2 introns, respectively. The coding DNA sequences are 90% identical but the degree of isology is very high at the polypeptide level (more than 97% strict identities). The ANT1 and ANT3 alpha-tubulin amino acid sequences were compared to the corresponding sequence of the mesophilic alga Chlamydomonas reinhardtii. Of the 15 substitutions detected in ANT1 and/or ANT3, 5 are common to both psychrophilic algae. The recorded substitutions have been analyzed in terms of cold adaptation on the basis of the available three-dimensional structure of the alpha,beta-tubulin heterodimer from pig brain. Most of these are subtle changes, but two substitutions, M268V and A295V occurring in the region of interdimer contacts, could be of great significance for the cold stability of Antarctic algae microtubules due to the fact that the entropic control of microtubule assembly is particularly high in cold adaptes species.

A psychrophilic green alga belonging to the Chloromonas genus and here named ANT1 was collected in Antarctica. The activities of two enzymes, nitrate reductase and argininosuccinate lyase, were measured at various temperatures and compared to the corresponding enzyme activities in the mesophilic species Chlamydomonas reinhardtii Dangeard. For both enzymes, the temperature for apparent optimal activity was about 20°C lower in ANT1 than in C. reinhardtii. The enzymes were also submitted to various heat treatments before measuring their activities. Both psychrophilic enzymes were more sensitive to heat than the corresponding mesophilic enzymes. It is worth stressing, however, that in both species nitrate reductase was much more sensitive to heat than argininosuccinate lyase, which probably indicates that the peculiar structure of each protein primarily determines its dependence to temperature. Secondary adaptations to low temperatures should then occur to confer the psychrophilic character.

The gene encoding the extracellular, active‐site serine β‐lactamase of Actinomadura R39, previously cloned into Strptomyces lividans, has the information for the synthesis of a 304 amino acid protein, the amino terminal region of which has the characteristic features of a signal peptide. The Actinomadura R39 β‐lactamase is another member of the class A β‐lactamases. In particular, it shows high homology with the β‐lactamase of Bacillus licheniformis.