Ontogeny of the proventitious epicormic buds in Quercus petraea.

In the present work, we described the fate of proventitious epicormic buds on the trunks of 40-year-old Quercus petraea trees and in parallel the vascular trace they produced in the wood. Our results show that small and large individual epicormic buds can survive as buds for 40 years and that both are composed of a terminal meristem and scales. Meristematic areas are detected in the scale axils of small buds; in addition to these meristems the large buds also have secondary bud primordia. The small buds are connected to the pith of the main stem by a unique trace, whereas the large buds are connected by one or multiple traces. A single trace might imply that the whole bud is still alive and multiple traces might indicate that the terminal meristem has died. In the latter case, each trace is connected to a secondary bud of the large bud. The buds found in a cluster are composed of a terminal meristem and scales with axillary meristems in the scale axils. A cluster is connected to the pith of a stem either by a unique trace when it seems to be the result of partial abscission of an epicormic shoot or multiple traces when it might have originated from an epicormic bud in which the terminal meristem has died. Whatever the type of the bud, the vascular trace in the bark is composed of a cambium, secondary xylem and parenchyma cells and the trace present in the wood had parenchyma cells with vestiges of secondary xylem. Each year, the vascular trace should be produced in the bark by the cambium of the tree but not by the bud itself. On 40-year-old Q. petraea, we observed a proliferation of epicormic buds and in parallel a multiplication of the number of vascular traces in the trunk, but the knots caused by the traces of epicormic buds in the wood, either as individuals or in clusters, are minor since their colours are only slightly darker than those of woody rays and they are less than 2 mm in diameter. The knots will appear when epicormic buds develop into shoots. Received: 30 March 1999 / Accepted: 09 June 1999     

Rapid group separations of nucleotides and related compounds on silica columns

Nucleosides, bases, and nucleotides can be separated from one another rapidly (10–15 min) on 1-ml silica cartridges. Samples adjusted to 4 mm ammonium borate, 90% acetonitrile are loaded onto 1-ml columns equilibrated with the same solvent. Bases do not absorb to the silica under these conditions. Nucleosides are eluted with 16 ml of 0.5 m acetic acid in 90% acetonitrile. Nucleotides are then eluted with water. The 1-ml silica columns have performed well with samples up to 10 ml in volume. We have found the procedure to be quantitative and the gels to have high capacity (61 μmol Cyd/ml silica). Acid extracts from a large number of cells (10⁸) have been processed on a single cartridge.     

Trifluoperazine Activates and Releases Latent ATP-Generating Enzymes Associated with the Synaptic Plasma Membrane

Neurone-specific enolase (NSE) and the brain form of creatine phosphokinase (CPK-BB) were previously found to be present in rat synaptosomal plasma membranes (SPM) using two-dimensional gel (2-D gel) and peptide analysis; enzymatic activities of these and of pyruvate kinase (PK), all involved in ATP generation, were shown to be "cryptic" unless the SPM were treated with Triton X-100. We now show that enzymatic activation also occurs when the SPM are treated with trifluoperazine (TFP). TFP activation occurred even when the enzymes were membrane associated, showing that solubilization was not responsible for "unmasking" the enzyme activities. When TFP treatment was performed at alkaline instead of neutral pH, NSE and CPK-BB were released as well as PK, nonneuronal enolase, and aldolase which were identified by 2-D gel and tryptic peptide analysis. Other proteins released included calmodulin, actin, and the 70-kilodalton heat-shock cognate protein. Tubulin, synapsin I, and a 35-kilodalton basic protein were largely unaffected. The latter was identified as the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase on the basis of 2-D gel and peptide analyses and subsequent partial sequencing of a rat brain cDNA coding for the same protein. TFP treatment is thus useful for activating latent enzymes as well as for distinguishing enzymes that have a different disposition on the membrane.     

Purification and properties of the DNA-binding protein HPB12 from Bacillus subtilis nucleoid

We report the purification to homogeneity of a 12 KDa protein (HPB12) present in the nucleoids of Bacillus subtilis. From the purification data the abundance of the protein was estimated to about 20,000 monomers per cell. The HPB12 protein is heat-stable and acid-soluble and binds preferentially to supercoiled and linearized double-stranded DNAs. The binding of the protein to the supercoiled DNA occurs very rapidly and appears to be cooperative. Moreover, the complexes are extremely stable and do not dissociate after 90 min. These properties are consistent with a role of the HPB12 protein in the structure of the B. subtilis chromosome.     

Structure dynamics of the hemoglobin mutants Hb H?tel Dieu, HbG Philadelphia, HbJ Mexico, Hb St. Mandé and Hb San Diego, studied by nanosecond-laser-flash photolysis

The kinetics of the change from the carboxy to the deoxy conformation of the mutated hemoglobins mentioned in the title and of normal human adult hemoglobin were determined from measurements of light absorption changes occurring up to 50 microseconds after nanosecond-laser photodissociation of the corresponding CO complexes. The spectral evolution of the mutated hemoglobins was found to be similar in its main features to that of normal hemoglobin. The kinetics could be decomposed into two phases with rates 1.1-1.8 x 10(6) s-1 and 0.17-0.34 x 10(6) s-1 (except Hb St. Mandé which displayed only the faster phase). Study of the mutated subunits of HbJ Mexico (alpha subunit) and Hb H?tel Dieu (beta subunit) showed that they convert exponentially to the stable deoxy state after photodeligation at the same rates as the corresponding subunits of normal Hb: 1.1 x 10(6) s-1 (alpha) and 0.3 x 10(6) s-1 (beta). The results indicate that there is no direct correlation between the kinetics of spectral relaxation in the time range studied and the oxygenation properties for these hemoglobins. However, there is some indication that the kinetics are dependent upon the region of mutation.     

Functional and spectral characterization of the respiratory chain of Chloroflexus aurantiacus grown in the dark under oxygen-saturated conditions

In this paper we attempt a functional and spectral characterization of the membrane-bound cytochromes involved in respiratory electron transport by membranes from cells of Chloroflexus aurantiacus grown in the dark under oxygen saturated conditions. We conclude that the NADH-dependent respiration is carried out by a branched respiratory chain leading to two oxidases which differ in sensitivity to CN^- and CO. The two routes also show a different sensitivity to the ubiquinone analogue, HQNO, the pathway through the cytochrome c oxidase being fully blocked by 5 M HQNO, whereas the alternative one is insensitive to this inhibitor. The cytochrome c oxidase containing branch is composed by at least two c-type haems with E _m 7.0 of +130 and +270 mV ( bands at 550/553 nm and 549 nm, respectively), plus a b-type cytochrome with E _m 7.0 of +50 mV ( band at 561 nm). From this, and previous work, we conclude that respiratory and photosynthetic electron transport components are assembled together and function on a single undifferentiated plasma membrane.Abbreviations HQNO heptylhydroxy-quinoline-N-oxide - UHDBT undecyl-hydroxydioxobenthiazole - Q/b-c ubiquinol/cytochrome c oxidoreductase complex - BChl bacteriochlorophyll     

Characterization of proteins that associate with an unglycosylated form of the transferrin receptor in A431 cells

A protein doublet (Mr = 135,000/130,000) was found to coprecipitate with an unglycosylated form of the transferrin receptor in tunicamycin-treated A431 cells. This doublet is not detected with either a monoclonal or polyclonal antibody to the transferrin receptor on Western blots indicating that these proteins do not interact directly with transferrin receptor antibody. Proteolytic digestion patterns of the individual proteins of the Mr = 135,000/130,000 doublet suggest that they are related to one another and are distinct from the transferrin receptor. Further characterization of these proteins indicates that they form a high molecular weight complex with the unglycosylated but not the glycosylated form of the transferrin receptor. Pulse-chase experiments demonstrate that the proteins post-translationally associate with the receptor.     

Usefulness of linked DNA probes for prenatal diagnosis of cystic fibrosis: report of a case in a 1:4 risk pregnancy

Prenatal diagnosis of cystic fibrosis was performed with linked DNA probes in a couple with a 1:4 risk. The limits and the future of molecular prenatal diagnosis are discussed.