PubMed Health⌕ Search

Biomedical subjects

J Marechal

Publications and source records attributed to J Marechal.

13 recordsLinked to original sources
PubMed1999

Mutation at position -12 of intron 45 (c-->t) plays a prevalent role in the partial skipping of exon 46 from the transcript of allele alphaLELY in erythroid cells.

Allele alphaLELY is a common low-expression allele of the erythroid spectrin SPTA1 gene. It results in the aggravated expression of hereditary elliptocytosis due to SPTA1 gene mutations occurring in trans. Allele alphaLELY contains, in particular, mutations in introns 45 and 46, both in polypyrimidine tracts, and causes the partial skipping of exon 46. The corresponding six amino acids belong to the nucleation site where the dimerization process of spectrin begins. In this work we investigated the cause of exon 46 partial skipping. We made four types of constructs with or without the intron 45 mutation, and with or without intron 46 mutation. Intron 45 mutation by itself dramatically triggered partial skipping of exon 46. Intron 46 mutation had no effect by itself. It was not possible to assess whether it modulated, even to a very small extent, the activity of intron 45 mutation. Taken together, intron 45 mutation is the prevalent, if not the exclusive, determinant of the partial skipping of exon 46 in the transcript of allele alphaLELY.

Alleles↗
PubMed1994

A deletional frameshift mutation in spectrin beta-gene associated with hereditary elliptocytosis in spectrin Napoli.

We studied a clinically manifest, dominantly transmitted elliptocytosis in an Italian family. We found a new spectrin variant, designated spectrin Napoli. Its beta-chain was truncated in its C-terminal region (apparent MW 216 kD). It displayed a low expression level (15%). There was a 8 nt deletion: CTTTTGAGAAGT-->CTGT (nt 6255-6262), starting after codon 2053. This deletion was followed by a 54 nt (18 amino acids) missense sequence and terminated by the TGA triplet which normally overlaps codons 2074 and 2075 (CTTGAG). The overall length of the mutated beta-chain was comparable to that found in spectrin Nice, spectrin Tokyo and spectrin Tandil, which are other variants with truncated beta-chains; however, a distinct nonsense codon was used in spectrin Napoli.

Adult↗
PubMed1994

A variant of spectrin low-expression allele alpha LELY carrying a hereditary elliptocytosis mutation in codon 28.

Allele alpha LELY is a low-expression allele of the erythroid spectrin alpha-gene. It carries mutations in exon 40 (alpha V/41 polymorphism) and intron 45, respectively, and is associated with partial skipping of exon 46. The latter phenomenon is thought to impair the recruitment of alpha-chains by beta-chains, and would eventually account for the low-expression character. When it occurs in trans to an alpha-allele responsible for hereditary elliptocytosis (alpha HE allele; alpha HE/alpha LELY diplotype), allele alpha LELY enhances the severity of elliptocytosis. Because allele alpha LELY is widespread, we anticipated that it would occasionally carry HE determinants. These variants of allele alpha LELY will be designated alpha HE-LELY allele. The HE component was the known alpha 28 Arg-->His mutation. This alpha HE-LELY allele was investigated within the alpha HE-LELY/alpha LELY diplotype, a diplotype not described before. Except for the neonatal period, the presentation was mild. In a consistent manner, the alpha LELY component in cis of the alpha HE mutation counteracted the like component in trans.

Alleles↗
PubMed1993

Detection of naturally occurring enteroviruses in waters by reverse transcription, polymerase chain reaction, and hybridization.

Comparison in virus-seeded mineral water of three detection methods for enteroviruses, direct hybridization, cell culture, and reverse transcription into cDNA followed by polymerase chain reaction and hybridization, showed that the last procedure was 10 to 1,000 times more sensitive than detection by cell culture and 10(5) to 10(7) times more sensitive than direct hybridization. The presence of naturally occurring enteroviruses was also demonstrated in activated sludge and in concentrated and non-concentrated surface water samples by reverse transcription-polymerase chain reaction-hybridization. However, in activated sludge and in concentrated surface waters, enzymatic amplification was sometimes inhibited by contaminants.

Animals↗
PubMed1991

Occurrence of the alpha I 22 Arg----His (CGT----CAT) spectrin mutation in Tunisia: potential association with severe elliptopoikilocytosis.

A category of spectrin alpha I domain variants are manifested by the increase of the alpha I 74 kDa fragment at the expense of the parent 80 kDa fragment following partial tryptic digestion. We describe a particular case of alpha I/74 abnormality in a Tunisian family. The propositus was severely ill and had an elliptopoikilocytosis. To the contrary, his father, who carried the same alpha I/74 variant, displayed no clinical signs and a few elliptocytes. The increase of the alpha I 74 kDa fragment was more pronounced in the propositus than in his father. Unexpectedly, the spectrin content was reduced to similar (and limited) extents in both of them, and the father displayed nearly as pronounced an increase of the spectrin dimer percentage as the propositus following low ionic strength extraction. In vitro spectrin dimer reconstitution experiments indicated that the primary mutation was located in the alpha-chain itself (not in the beta-chain as is the case in some alpha I/74 mutants). Following polymerase chain reaction (PCR) amplification, cloning and sequencing of exon 2 of spectrin alpha-gene in the father, we found the G----A substitution at position 2 of codon 22 (CGT----CAT; Arg----His). This mutation has been recently discovered in a family of French descent. Dot blot hybridization confirmed that the substitution was transmitted with the alpha I/74 abnormality. As previously shown, the enhancement of its expression level in the propositus, with respect to the father, was accounted for by the presence of a factor carried by the alpha-spectrin allele in trans and transmitted by the mother.

Adult↗
PubMed1990

A haemolytic syndrome associated with the complete absence of red cell membrane protein 4.2 in two Tunisian siblings.

We report on the complete absence of protein 4.2 in two Tunisian siblings. The propositus presented with a haemolytic anaemia that evolved in an intermittent fashion until she was cured by splenectomy. Her red cells had a normal morphology, as well as normal deformability upon osmotic gradient ektacytometry. SDS-polyacrylamide gel electrophoresis failed to reveal any protein 4.2. Using anti-protein 4.2 polyclonal antibodies. Western blots were also unable to detect protein 4.2. Preparation of inside out vesicles resulted in no detectable loss of ankyrin. The propositus's sister presented with a haemolytic anaemia but had not undergone splenectomy; she showed the same biochemical features. The two cases presented of missing protein 4.2 are the first ones to be described outside the Japanese population. Considered as homozygotes for some defect that must alter the protein 4.2 gene itself, they exemplify a unique syndrome pertaining neither to elliptocytosis nor to spherocytosis, at least not closely. The parents, who are first cousins and whom we regarded as heterozygotes, were clinically and morphologically normal; they had a normal content of protein 4.2. Therefore, the 4.2 (-) haemolytic anaemia appears as entirely recessive.

Adult↗