PubMed Health⌕ Search

Biomedical subjects

L Ferretti

Publications and source records attributed to L Ferretti.

62 records · Page 4Linked to original sources
PubMed1986

Total synthesis of a gene for bovine rhodopsin.

To carry out systematic structure-function studies of bovine rhodopsin by specific amino acid replacements, we have accomplished the total synthesis of its gene, which is 1057 base pairs long. The synthetic gene contains 28 unique restriction sites that are on the average 60 base pairs apart. Replacement of specific restriction fragments by synthetic counterparts containing the desired nucleotide changes permits specific mutagenesis in all parts of the gene. The synthesis of the gene involved enzymatic joining of a total of 72 synthetic oligonucleotides, 15-40 nucleotides long, to form DNA duplexes. The total gene was assembled from three synthetic fragments that were cloned. All synthetic oligonucleotides were characterized by 5'-end analysis, and the accuracy of the joining reactions was confirmed by sequencing the three fragments as well as the complete gene.

Animals↗
PubMed1984

Possible hyperattenuation of transcription in the Escherichia coli hisG gene cloned in Bacillus subtilis.

The expression of the E. coli hisG gene in B. subtilis cells does not occur in spite of the faithful replication of the relevant DNA fragment cloned in this host by means of a plasmid vector, pHV14 , capable of replication in both B. subtilis and E. coli. Analysis of the RNA transcribed in vitro and in vivo by the B. subtilis RNA polymerase on the cloned hisG sequence indicates that in B. subtilis cells the physiological his operon promoter is not recognized. Transcription is initiated at many sites, some of which are located upstream of and some are located downstream of the his operon promoter. These "adventitious" promoters give rise to convergent transcription products which stop at, or in the vicinity of, the his operon attenuator sequence.

Bacillus subtilis↗
PubMed1981

Specific and reversible inhibition of the blunt end joining activity of the T4 DNA ligase.

Specific, complete and reversible inhibition of the joining of blunt ended DNA duplexes catalyzed by the T4 DNA ligase can be obtained by using ATP, the enzyme cofactor, at concentrations of 5 mM and higher. On cohesive DNA ends, 5 mM ATP, which completely inhibits blunt end ligation, brings about only a limited (8%) reduction in the level of joining obtainable under optimal ATP concentration (0,5 mM or lower). A similar but less drastic uncoupling of the two kinds of joining can be achieved at lower ATP concentration (2,5 mM) using 1 mM Mg++. The joining of DNA blunt ends can also be inhibited almost completely by 10 mM spermidine, without noticeable effect on the joining of cohesive termini.

Adenosine Triphosphate↗
PubMed1981

Temperature dependence of the joining by T4 DNA ligase of termini produced by type II restriction endonucleases.

The temperature dependence of the T4 DNA ligase-catalyzed joining of plasmid DNA linearized by the action of HaeIII, EcoRI and PstI restriction endonucleases has been investigated by electron microscopy analysis. The extent of joining is maximal at 4 degrees and decreases with increasing temperatures following sigmoid-like curves. The temperature at which 50% of the maximal reaction is still observable increases going from DNA termini without single-stranded overlaps (produced by HaeIII) to termini with four nucleotides overlap, composed only by two A and two T (produced by EcoRI) to termini with four nucleotide overlap, composed by A, T, G and C (produced by PstI).

DNA Ligases↗
PubMedDate not supplied

Convergent transcription of the Escherichia coli hisG gene cloned in Bacillus subtilis stops in the vicinity of the attenuator.

A 5300-bp DNA segment containing the promoter, the attenuator and the first gene (hisG) of the Escherichia coli his operon has been inserted into an interspecific E. coli-Bacillus subtilis plasmid vector, pHV14. The resulting plasmid pPV48 restores the His+ phenotype to an E. coli hisG mutant, but fails to do so to a corresponding B. subtilis mutant. Experiments aimed at localizing the block to this heterologous expression in B. subtilis have shown that the enzymatic activity of the hisG+ gene product is neither detectable nor inhibited in crude extracts of B. subtilis cells harboring pPV48. Furthermore, electron microscopic, Southern blot and S1 mapping analysis of the transcripts produced in vitro and in vivo by B. subtilis RNA polymerase indicate that the hisG+ region is transcribed, but that the transcripts initiate at sites different from the his promoter, converge towards, and terminate in the vicinity of the attenuator.

Bacillus subtilis↗
PubMedDate not supplied

[Treatment of post-phlebitic syndrome].

The Authors report their experience in the treatment of the post phlebitic syndrome at ulceration stage. The therapy is based on three important points: a first medical treatment and later saphenous striping with a specific tying of the insufficient perforant veins to consolidate the results of scarification in the future; finally ther removal of plugs of fascia for the therapy of hypodermitis with a personal technique.

Bandages↗