Linked Life Data

7916684

Source:http://linkedlifedata.com/resource/pubmed/id/7916684

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1993-3-23
pubmed:databankReference
pubmed:abstractText
Liver-type L-arginase is a major urea-cycle enzyme which is strongly induced during amphibian metamorphosis, but little is known about the molecular mechanisms underlying this induction. As a first step towards elucidating the possible mechanisms, we have isolated a cDNA clone for L-arginase from an adult Xenopus laevis liver cDNA library. Sequence comparison of Xenopus liver-type L-arginase cDNA shows a strong conservation at the amino acid level with those of human, rat and yeast. Using a Xenopus arginase cDNA fragment as a hybridization probe, we have shown by Northern blotting that the gene is highly expressed in the liver, and very slightly in kidney and spleen, of adult Xenopus. The expression is developmentally regulated. Only traces of arginase mRNA can be detected in pre-metamorphic tadpoles, but its accumulation increases very markedly at the onset of natural metamorphosis, being maintained at a high concentration constitutively upon completion of this developmental process. Amphibian metamorphosis is under the strict control of thyroid hormones. It is therefore significant that exposure of pre-metamorphic tadpoles (at stages before endogenous thyroid hormone secretion) to exogenous hormone (1 nM triiodothyronine) precociously activated the L-arginase gene. The time course of this precocious hormonal induction paralleled that of serum albumin gene in the liver. Polyclonal antibodies were raised against recombinant Xenopus L-arginase expressed in Escherichia coli as a fusion protein with glutathione S-transferase in the plasmid expression vector pGEX. Western blotting using this antibody showed that, although arginase mRNA is present in high concentration in Xenopus tadpole liver at the onset of natural metamorphosis, the protein is detected only upon its completion. Our results show a complex transcriptional and post-transcriptional regulation of the Xenopus liver-type L-arginase gene during post-embryonic development. They also demonstrate that this gene can be exploited as a target for thyroid hormones in further studies to analyze the mechanisms underlying the establishment of the adult phenotype during amphibian metamorphosis.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
1
pubmed:volume
211
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
891-8
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Developmental and hormonal regulation of the Xenopus liver-type arginase gene.
pubmed:affiliation
Laboratory of Developmental Biochemistry, National Institute for Medical Research, Mill Hill, London, England.
pubmed:publicationType
Journal Article, Comparative Study