The duplication in Charcot-Marie-Tooth disease type 1a spans at least 1100 kb on chromosome 17p11.2

Summary Recently, it has been shown that Charcot-Marie-Tooth disease type 1a (CMT1a) is linked with a duplication of a DNA segment that is detected by probe VAW409R3, and that is located on chromosome 17p11.2. Here, we show that this duplication also contains VAW412R3a, but not A10-41 and EW503. Accounting for the duplication in recombination analysis, we found recombinants between CMT1a and EW301 and EW502, but not with A10-41, VAW409R3, and VAW412R3. Using pulsed-field gel electrophoresis analysis, we estimated the minimal size of the duplicated region in CMT1a patients to be 1100 kb.     

Purification and characterization of fatty-acid-binding proteins from rat heart and liver

Fatty-acid-binding proteins were purified from delipidated cytosols of rat heart and liver by gel filtration and anion-exchange chromatography at pH 8.0 and by repeated gel filtration, respectively. Homogeneity of both proteins was demonstrated by a single band on polyacrylamide gels; each had a molecular weight of about 14 000. Liver fatty-acid-binding protein is more basic (pI, 8.1) than that of heart (pI, 7.0) and contains more basic amino acids. Examination of fatty acid binding by the binding proteins from heart and liver revealed the presence of a single class of fatty-acid-binding sites in both cases with an apparent dissociation constant for palmitate of about 1 microM. Liver fatty- acid-binding protein shows similar binding characteristics for palmitate, oleate and arachidonate. Palmitate bound to heart fatty- acid-binding protein was a good substrate for oxidation by rat heart mitochondria. The results show that the fatty-acid-binding proteins from rat heart and liver are closely related, but that they are distinct proteins.     

Imino-proton resonances of yeast tRNAPhe studied by two-dimensional nuclear Overhauser enhancement spectroscopy

Application of two-dimensional nuclear Overhauser enhancement (NOE) spectroscopy to yeast tRNAPhe in H2O solution demonstrates that all imino-proton resonances, related to the secondary structure, and nearly all imino proton resonances, originating from the tertiary structure, can be assigned efficiently by this method. The results corroborate the assignments of the imino-proton resonances of this tRNA as established previously by one-dimensional NOE experiments (only the assignment of base pairs G1 X C72 and C2 X G71 should be reversed). The advantages of two-dimensional NOE spectroscopy over one-dimensional NOE spectroscopy for the assignments of imino-proton resonances and the structure elucidation of tRNA are illustrated and discussed. Furthermore, the use of non-exchangeable proton resonances as probes of the molecular structure is explored.     

Degradation of halogenated aliphatic compounds by Xanthobacter autotrophicus GJ10

A bacterium that is able to utilize a number of halogenated short-chain hydrocarbons and halogenated carboxylic acids as sole carbon source for growth was identified as a strain of Xanthobacter autotrophicus. The organism constitutively produces two different dehalogenases. One enzyme is specific for halogenated alkanes, whereas the other, which is more heat stable and has a higher pH optimum, is specific for halogenated carboxylic acids. Haloalkanes were hydrolyzed in cell extracts to produce alcohols and halide ions, and a route for the metabolism of 1,2-dichlorethane is proposed. Both dehalogenases show a broad substrate specificity, allowing the degradation of bromine- and chlorine-substituted organic compounds. The results show that X. autotrophicus may play a role in the degradation of organochlorine compounds and that hydrolytic dehalogenases may be involved in the microbial metabolism of short-chain halogenated hydrocarbons in microorganisms.     

A restriction enzyme cleavage map of the histidine utilization (hut) genes of Klebsiella aerogenes and deletions lacking regions of hut DNA

Summary The histidine utilization (hut) operons of Klebsiella aerogenes were cloned into pBR322. The hut genes are wholly contained on a 7.9 kilobase pair fragment bounded by HindIII restriction sites and expression of hut is independent of the orientation of the fragment with respect to pBR322. A restriction map locating the 27 cleavage sites within hut for the enzymes, HindIII, PvuII, SalI, BglII, KpnI, PstI, SmaI, AvaI, and BamHI was deduced. Several of the cleavage sites for the enzymes HaeIII and HinfI were also mapped. A set of deletion plasmids was isolated by removing various restriction fragments from the original plasmid. These deletions were characterized and were used to assist in mapping restriction sites. This physical characterization of hut DNA opens the way for genetic and molecular analysis of the regulation of hut gene expression in vitro as well as in vivo.     

The influence of Ca2+ on the turbidity of DPPC-DMPA vesicles within the temperature range of the phase transition

The influence of the addition of Ca2+ on the phase behaviour of vesicles, composed of dipalmitoylphosphatidylcholine (DPPC) and dimyristoylphosphatidic acid (DMPA) in a ratio of 4 to 1, has been investigated by means of turbidity measurements. As expected one single phase transition for the mixed phospholipids was observed in the absence of Ca2+. Passing through the temperature range of this transition after the addition of Ca2+, conditions appeared to favor fusion of the vesicles. A possible reason for this is that during the transition Ca2+ may permeate through the vesicle membranes and gain access to the inside DMPA binding sites. Therefore it is not unambiguously possible to determine phase transition temperatures from the turbidity changes that occur under these conditions. However, when within the temperature range of the phase transition of the mixed phospholipids the influence of Ca2+ addition to the vesicles was recorded isothermally, at each temperature separately, the final plot of turbidity versus temperature turned out to be far less confused by fusion events and adopted the form of two separate phase transitions. The temperatures at which these two transitions occur closely resemble the phase transition temperatures that may be observed in the absence of Ca2+ for DMPA and DPPC alone, 39 degrees C and 43 degrees C respectively. The results of this study suggest that when Ca2+ has only access to the outside of the vesicle membranes it may segregate the neutral and the acidic phospholipids into separate domains, both domains adopting their proper phase condition at the actual temperature.(ABSTRACT TRUNCATED AT 250 WORDS)     

A numerical analysis of steady flow in a three-dimensional model of the carotid artery bifurcation

A finite element approximation of steady flow in a rigid three-dimensional model of the carotid artery bifurcation is presented. A Reynolds number of 640 and a flow division ratio of about 50/50, simulating systolic flow, was used. To limit the CPU- and I/O-times needed for solving the systems of equations, a mesh-generator was developed, which gives full control over the number of elements into which the bifurcation is divided. A mini-supercomputer, based on parallel and vector processing techniques, was used to solve the system of equations. The numerical results of axial and secondary flow compare favorably with those obtained from previously performed laser-Doppler velocity measurements. Also, the influence of the Reynolds number, the flow division ratio, and the bifurcation angle on axial and secondary flow in the carotid sinus were studied in the three-dimensional model. The influence of the interventions is limited to a relatively small variation in the region with reversed axial flow, more or less pronounced C-shaped axial velocity contours, and increasing or decreasing axial velocity maxima.     

An experimental setup for the measurement of forces on a human cadaveric foot during inversion

An experimental setup was developed for statically measuring seven vertical and three horizontal reaction forces on the foot. In the setup, the leg can be simultaneously loaded (1) by a vertical force, (2) by an externally applied axial moment, and (3) by simulated muscle forces. The foot is free to invert under influence of the external loads. Statical analysis and test experiments were used for evaluation. The setup can be used in combination with Roentgen photogrammetry to measure bone positions simultaneously with forces.