Biomedical subjects

J N Freund

Publications and source records attributed to J N Freund.

42 records · Page 3Linked to original sources

PubMed1990

Comparative expression of the mRNA for three intestinal hydrolases during postnatal development in the rat.

The distribution of the mRNA for intestinal aminopeptidase-N, lactase-phlorizin hydrolase and sucrase-isomaltase was compared during rat postnatal development as well as along the longitudinal axis of the intestinal tract including small-intestine and colon. We found out that each mRNA exhibited a specific pattern of accumulation, suggesting proper regulation steps for the expression of the corresponding digestive enzymes.

Aminopeptidases↗

PubMed1989

Discrepancy between the intestinal lactase enzymatic activity and mRNA accumulation in sucklings and adults. Effect of starvation and thyroxine treatment.

The accumulation profile of intestinal lactase mRNA was investigated in suckling and adult rats and pigs. We found no correlation between the lactase enzymatic activity and the accumulation of the messenger at both developmental stages. Modulation of lactase activity by starvation or thyroxine treatment had no effect on lactase mRNA accumulation in the rat intestine. These results confirm that thyroxine modulates lactase expression essentially at the post-transcriptional level.

Age Factors↗

PubMed1989

The gene for intestinal sucrase-isomaltase as member of a gene family.

The synthetic oligonucleotide MF59, derived from the rabbit sucrase-isomaltase cDNA sequence, hybridizes to two classes of mRNA in the rat and pig intestinal epithelium as well as to various restriction fragments within the human genome. These results strongly support the hypothesis that the sucrase-isomaltase gene belongs to a gene family. The cloning of a human cosmid containing such a sequence similar to MF59 has allowed us to identify a new member of this gene family which detects a single 6.5 Kb intestinal mRNA in the adult pig.

Amino Acid Sequence↗

PubMed1987

The rudimentary gene of Drosophila melanogaster encodes four enzymic functions.

We have determined the 7168 nucleotide DNA sequence corresponding to the messenger RNA of the rudimentary gene of Drosophila melanogaster. By sequence comparison with genes involved in the pyrimidine pathway of prokaryotes and lower eukaryotes, we conclude that the rudimentary gene encodes four enzymically different functions. Each function is restricted to a specific coding domain but in an order different from that previously defined by genetic data. We have found that the corresponding mammalian gene, the CAD gene, exhibits a similar functional organization, and we propose schemes for the evolution of the corresponding coding sequences.

Amidohydrolases↗

PubMed1986

Molecular organization of the rudimentary gene of Drosophila melanogaster.

We have determined the molecular structure of the rudimentary gene of Drosophila melanogaster. The transcription unit, which extends over 14,000 bases, is split into seven exons and six introns. Sequences presenting homologies with a TATA box and a CAT box are located upstream from the transcription initiation site, and there is a consensus polyadenylation signal in the vicinity of the 3' end of the messenger RNA coding sequence. Short intronic sequences fit well with consensus signals found in other eukaryotic genes and involved in the splicing of the precursor messenger RNA. Partial genomic and complementary DNA sequencing has revealed stretches of amino acid sequence homologies with the corresponding enzymes in Saccharomyces cerevisiae and Escherichia coli. This is in good agreement with the genetic map of the locus, which indicates that the enzymic activities encoded by the gene are organized linearly along the DNA.

Amino Acid Sequence↗

PubMed1986

Organization of transcription units around the Drosophila melanogaster rudimentary locus and temporal pattern of expression.

The molecular organization of 90 kb of DNA derived from a region of the X chromosome that encompasses the rudimentary locus of D. melanogaster is presented. This segment spans the cytogenetic region 14F2-3 to 15A1-2, and there are, in addition to the rudimentary gene several transcription units present, whose functions are still unknown. We have determined the pattern of expression of all these genes at several stages of development, and found that they all show a different temporal modulation of their activity. The accumulation of the r product correlates well with the enzymatic activity determined for the protein product of the gene, being highest in very early embryos and adult females.

Animals↗