A note on the preparation and use of a selective differential medium for the isolation of Acinetobacter spp. from clinical sources

A selective, differential medium is reported for the isolation of Acinetobacter spp. With this medium it was found that not one of 30 people carried Acinetobacter spp. in their faeces, but 2 of 40 individuals carried it on their skin.     

Inhibiteurs non acides et dormance embryonnaire chez Taxus baccata

Non-acidic inhibitors and embryo dormancy in Taxus baccata L. Embryo dormancy of Taxus baccata is eliminated when the embryos are continuously kept in sterile nutritive liquid medium. After 3 weeks of culture, an important non-acidic inhibitory complex can be extracted from this liquid medium. At least three substances are involved: two pigments and a compound with some properties that suggest xanthoxin. These substances are neither found in embryos taken directly from the seeds, nor in liquid medium after 8 days of culture, which is the time necessary and sufficient to allow germination after transfer on agar medium. Such behaviour is quite different from that of ABA previously studied and indicates that these non-acidic inhibitors appear late during the culture and are not directly involved in embryo dormancy.     

Optimization of monoclonal antibody immobilization on hydrazide-preactivated hollow fiber membrane.

Immobilization of an IgG1 monoclonal antibody (MAb) was optimized using a unique hydrazide-preactivated hydrophilic hollow fiber membrane as the support matrix. Modules containing 0.42 milliliters of membrane volume (mlmv) were offered varying amounts of purified MAb. The highest immobilization efficiency on the hollow fiber membranes was 88% at a MAb loading concentration of 0.35 mg/ml. The optimum range of MAb concentrations to achieve the best immobilization efficiency was 0.18-0.45 mg/ml. A larger module containing 9.7 mlmv immobilized greater than 3.0 mg MAb/mlmv at an efficiency of greater than 90%. The total amount of MAb immobilized on the membranes within each module was in direct proportion to the total amount of membrane volume. Preliminary data suggest the optimized immunoaffinity hollow fiber membrane matrix produced in this study is stable and can achieve a product capacity of greater than 2.0 mg/mlmv. In concert with an automated fluid handling system, such as the TRIO(TM) Bioprocessing System, rapid accurate information can be easily generated on process parameters and scale-up considerations where an immunoaffinity step is included in the downstream purification protocol.     

c-AMP and Morphogenesis of Acetabularia

The c-AMP content has been found to double when Acetabularia develop from 5–10 mm long to grown or almost full-grown algae.
The biological significance of this fact has been approached by studying the effects of drugs known to influence the intracellular c-AMP content on the development of Acetabularia. When grown in the presence of theophyllin or papaverin, inhibitors of phosphodiesterase, the Acetabularia display a striking response during the exponential growth period; the final length, however, is not affected. Both substances increase the c-AMP content of the algea. Isoproterenol, which activates adenylate cyclase in many systems, also influences Acetabularia during the exponential growth period and, in addition, slightly affects cap formation.
The change in c-AMP content in the course of development and the effects of drugs influencing (theophyllin and papaverin) or likely to influence (isoproterenol) the c-AMP content of the algae suggest that this nucleotide plays a role at the time of intense growth.
The same phosphodiesterase activity has been found in the 5–10 mm and the 19–25 mm long algae, whereas two enzymes were found in cap-bearing Acetabularia.
The results are discussed as well as the involvement of c-AMP in the development of this alga.     

Structural and functional analysis of nitrogenase genes from the broad-host-range Rhizobium strain ANU240

The genes encoding the structural components of nitrogenase, nifH, nifD and nifK, from the fast-growing, broad-host-range Rhizobium strain ANU240 have been identified and characterized. They are duplicated and linked in an operon nifHDK in both copies. Sequence analysis of the nifH gene from each copy, together with partial sequence analysis of the nifD and nifK genes, and restriction endonuclease analysis suggested that the duplication is precise. Comparison of the Fe-protein sequence from strain ANU240 with that from other nitrogen-fixing organisms revealed that, despite its broad host range and certain physiological properties characteristic of Bradyrhizobium strains, ANU240 is more closely related to the narrow-host-range Rhizobium strains than to the broad-host-range Bradyrhizobium strains. The promoter regions of both copies of the nif genes contain the consensus sequence characteristic of nif promoters, and functional analysis of the two promoters suggested that both nif operons are transcribed in nodules.