Functional architecture of the ligamentum arteriosum in adults]

The ligamentum arteriosum was studied in eight normal adult human hearts obtained at autopsy. Four of these hearts were treated by the Zemper method and extensively dissected under a steromicroscope (from X 6 up to X 40); two were embedded in celloidin and sectioned at 100mugm; two were embedded in paraffin and sectioned one 50mugm and the other at 75 mugm. Section were stained by the axan and the resorcin-fuchsin methods. Unstained sections were examined under polarized light.The ligamentum arteriosum may be considered as a small smooth muscle, whose origin is in the arteria pulmonalis sinistra and the insertion in the arcus aortae. Therefore, the ligamentum arterisum may be considered as a myoelastic system, included in a collagenous stroma. Muscle, elastic and collagen fibers present a cross-spiral disposition. Being a myoelastic system with a collagen component, the ligamentum arteriosum cannot be considered as a simple arcus aortae support; it must play some functional role in controlling the arcus aortae curvature during the several different steps of the cardiac cycle.     

Stimulation of the lysogenization of Pseudomonas aeruginosa cells by phage transposon B39 induced by plasmid Rms163

The influence of Rms163 plasmid on lysogenization of Pseudomonas aeruginosa cells by B39 phage was studied. Plasmid Rms163 was shown to increase the frequency of lysogenization of PAO1 cells 7-8 times. C-mutants of B39 phage were isolated. According to complementation test, c-mutants were distributed into two groups--cI and cII/III. The product of cI is essential for establishment and maintenance of lysogenic state, cII/cIII product being only necessary for establishment of lysogenization. The mutants with special characteristics were isolated: B39cx1 phage carries a mutation which seems to be located on a regulatory site essential for establishment of lysogenic state. The region of the B39 genome responsible for interaction with Rms163 plasmid was mapped. Possible mechanisms of Rms163 plasmid interference with transposable B39 phage are discussed.     

Errors Related to Different Techniques of Intraperitoneal Injection in Mice

We found a 12% error in the placement of intraperitoneal injections of mice with the one-man procedure of injection. With a two-man procedure, the incidence of error was consistently reduced to 1.2%.     

The use of an enzymatic kit to measure plasma creatinine in the mouse and three other species

Plasma creatinine concentrations were determined in mice, rats, dogs and humans using a kinetic alkaline picrate method and an enzymatic method with a centrifugal analyser. Lower creatinine values were obtained for all four species using the enzymatic method, but the differences between methods were greater for mice and rats. Removal of creatininase from the enzymatic method reagents gave proportionally higher values for non-creatinine chromogens in mice and rats. A single enzymatic method was not specific for creatinine when used for these species.     

The human ASM (adult skeletal muscle) gene: expression and chromosomal assignment to 11p15

A rat adult skeletal muscle probe (Asm15) originated from a rhabdomyosarcoma was used to isolate the human homologous sequence from a placenta cDNA library. Among several positive clones the longest EcoRI-EcoRI insert (ASM1) obtained was 1875 bp long with 72% homology with rat Asm15 cDNA sequence. Important variations of ASM1 RNA level were observed in different adult skeletal muscles. Expression of a 29kD ASM1 protein was demonstrated in human adult skeletal muscle lysates using an antiserum (PB1579) raised against the C terminal region of the rat Asm15 protein. The human ASM gene was assigned by somatic cell analysis with human (ASM1) and rat (Asm15) probes to chromosome 11, and by in situ hybridization with the human probe to 11p15, a chromosome region involved in human embryonal rhabdomyosarcomas. Except for the presence of a HindII restriction site, the results obtained for the restriction map and the sequence of ASM1 cDNA (data not shown) exhibited extensive homology with the human H19 DNA sequence which have been mapped with a mouse probe also in 11p15. This suggests that ASM/Asm and H19 may represent the same sequence (in this hypothesis the presence of the supplementary HindII site in our ASM1 probe is explained by polymorphic variability). However it was reported that human and mouse H19 mRNA did not encode for a protein but acted as an RNA molecule whereas in our present study ASM protein was detected in human adult skeletal muscle. This could be explained by important regulation of ASM protein expression during development and cell differentiation. However we cannot exclude for the different species studied (mouse, rat, and man) the hypothesis that H19 and ASM/Asm mRNA may represent two distinct messengers from the same gene or even from duplicated genes.     

Cloning of chloroplast psbA and rbcL-genes from cotton Gossipium hirsutum

The fragments of cotton Gossipium hirsutum c.v. 108-f chloroplast genome were cloned in Escherichia coli cells. The cloned psbA and rbcL genes have been selected using the heterologous probes from spinach. The preliminary attempts to clone the complete psbA gene in pUC19 vector failed, probably, due to the toxicity of its product to Escherichia coli cells, and its 5'- and 3'-ends were cloned separately. Reconstruction experiments revealed that while the complete psbA gene was unable to be stably inherited by Escherichia coli cells, its structural part lacking the promoter region could be readily cloned in the bacterial cells.