It has recently been shown that the neurological mutant mouse staggerer (sg) harbors a deletion within the Rora gene that encodes the orphan nuclear receptor ROR alpha. This deletion removes an exon encoding part of the ligand binding domain of the putative receptor, generating an ROR alpha truncated protein (ROR alpha(sg)). It is unknown whether sg acts as a null or highly hypomorphic allele. To address this question, we have generated a null mutation of Rora by targeted disruption of its DNA binding domain in ES cells. The Rora-/- mice are viable but display tremor, body imbalance, small size and die between 3-4 weeks, similar to the sg mouse. Histological examination of the cerebellum of Rora-/- and sg mice showed similar defects, including small size and fewer ectopically localized Purkinje cells. Northern blot analysis of cerebellar RNA showed that ROR alpha transcripts are still expressed in the Rora-/- and sg mutants, although with altered mobilities. However, the cerebellum of the Rora-/- mutant does not express the ROR alpha protein. Attempts to complement the defect of the Rora-/- with sg failed, demonstrating conclusively that the sg defects are caused by the absence of functional ROR alpha.
A cDNA library was constructed from mRNA isolated from the liver of a 5-week-old female broiler chicken; at this age the level of insulin-like growth factor-I (IGF-I) mRNA was expected to be high. Three clones, of sizes 2.3, 0.86 and 0.2 kb, were isolated by using a homologous human (IGF-I) probe. The DNA sequence of these clones has been determined and the potential amino acid sequence deduced. The sequence of the mature chicken IGF-I peptide shows a high degree of homology with IGF-I from other species, providing evidence for the identity of these clones. Alternative splicing of the chicken IGF-I mRNA has been found in the region potentially encoding the leader peptide. This may give rise to two forms of prepeptide, differing in the length and nature of their leader peptide. The 0.86 kb cDNA has been used as a probe to Northern blots of chicken mRNA. A major band of approximately 0.65-0.85 kb was seen, plus several minor bands of larger molecular weights. Analysis of genomic Southern blots shows that there is one copy of the chicken IGF-I gene.
The cytoplasmic retinoic acid (RA)-binding protein CRABP-II is expressed widely throughout early morphogenesis in mouse embryo, but its expression becomes more restricted as organogenesis progresses. CRABP-II expression remains strong in the developing limb bud suggesting a role for this protein in limb patterning. Here, we show that the CRABP-II promoter can direct expression of a lacZ transgene in a specific posterior domain during limb bud development. In order to investigate in more detail the role played by CRABP-II in RA signal transduction, we have also generated mice homozygous for a null mutation of this gene. CRABPII−/− mice are viable and fertile but show a developmental defect of the forelimb, specifically an additional, postaxial digit. This digit is generally, but not exclusively, limited to a single forepaw of an individual animal. The penetrance of the phenotype varies according to the genetic background, occurring most frequently on the inbred 129Sv background (50%), less frequently on the C57Bl/6 background (30%) and rarely on the outbred CD1 background (10%). This developmental abnormality implies a role for CRABP-II in normal patterning of the limb.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.