Biomedical subjects

N Orange

Publications and source records attributed to N Orange.

22 records · Page 2Linked to original sources

PubMed1991

Effect of growth temperature on several exported enzyme activities in the psychrotrophic bacterium Pseudomonas fluorescens.

In accordance with previous results, the activity of extracellular proteases from Pseudomonas fluorescens MF0 is maximal at a growth temperature of 17.5 degrees C, well below the optimal growth temperature. In addition, the activities of three periplasmic phosphatases display the same growth temperature optimum. Chemostat experiments have shown that it is the growth temperature itself and not the value of the growth rate that regulates these activities. In contrast, a foreign periplasmic phosphatase, expressed under the control of its own promoter, displays a different sensitivity toward temperature. We conclude that in the psychrotrophic strain P. fluorescens MF0, growth temperature exerts a specific control upon the activity of certain enzymes. The critical temperature (17.5 degrees C) is within the range of normal growth, suggesting that this control is probably different from a cold shock or heat shock response.

Acid Phosphatase↗

PubMed1988

Identification of viral antigenic determinants by monoclonal antibodies directed against Chilo iridescent virus (iridovirus type 6). Brief report.

Monoclonal antibodies (McAbs) obtained against Iridovirus type 6 (CIV) were characterized by Western blotting and/or immunoprecipitation. Seven McAbs were found to be strongly reactive with viral polypeptides of molecular weights 16 K and 18 K by Western blotting. Two McAbs were directed against a complex composed of 30 K, 50 K, and 100 K polypeptides, but failed to react with either of these free polypeptides. This finding could explain the faint reactivity of these McAbs in Western blotting and immunoprecipitation. The reactivity of the other McAbs with their antigenic determinants is also discussed.

Antibodies, Monoclonal↗

PubMed1986

Monoclonal antibodies against Chilo iridescent virus (iridovirus type 6). Brief report.

Mouse hybridomas producing antibodies against proteins of Chilo Iridescent Virus were established by fusions of X 63-Ag 8-653 myeloma cells with spleen cells from balb/c mice immunized with purified disrupted viral particles. Forty monoclonal antibodies to CIV proteins have been characterized. By ELISA, 4 categories of monoclonal antibodies were defined according to their ability to react with some selected viral protein fractions used as antigen. In preliminary studies, the specificity of 2 monoclonal antibodies for some viral polypeptides was determined by immunoblotting.

Animals↗

PubMedDate not supplied

Hypothesis: hyperstructures regulate bacterial structure and the cell cycle.

A myriad different constituents or elements (genes, proteins, lipids, ions, small molecules etc.) participate in numerous physico-chemical processes to create bacteria that can adapt to their environments to survive, grow and, via the cell cycle, reproduce. We explore the possibility that it is too difficult to explain cell cycle progression in terms of these elements and that an intermediate level of explanation is needed. This level is that of hyperstructures. A hyperstructure is large, has usually one particular function, and contains many elements. Non-equilibrium, or even dissipative, hyperstructures that, for example, assemble to transport and metabolize nutrients may comprise membrane domains of transporters plus cytoplasmic metabolons plus the genes that encode the hyperstructure's enzymes. The processes involved in the putative formation of hyperstructures include: metabolite-induced changes to protein affinities that result in metabolon formation, lipid-organizing forces that result in lateral and transverse asymmetries, post-translational modifications, equilibration of water structures that may alter distributions of other molecules, transertion, ion currents, emission of electromagnetic radiation and long range mechanical vibrations. Equilibrium hyperstructures may also exist such as topological arrays of DNA in the form of cholesteric liquid crystals. We present here the beginning of a picture of the bacterial cell in which hyperstructures form to maximize efficiency and in which the properties of hyperstructures drive the cell cycle.

Bacteria↗