RESUMO
The third postnatal week of mouse development is characterized by dramatic changes of gene expression in the small intestine. Although these changes are often assumed to reflect regulation at the level of transcription, to date there have been no direct investigations of this. In the current study we have used trehalase as a marker of intestinal maturation. Highly sensitive reverse transcriptase-polymerase chain reaction methods were developed for semi-quantitative analysis of both initial and mature transcripts, i.e., hnRNA and mRNA. Jejunums collected during normal development (specifically from postnatal days 8-21) showed parallel increases in the levels of trehalase hnRNA and mRNA. Likewise, when precocious gut maturation was elicited by dexamethasone administration on days 8-10, both initial and mature trehalase transcripts were significantly increased, although with a relatively slow time course. We conclude that both normal and glucocorticoid-induced maturation of trehalase expression reflect transcriptional activation. However, the slow time course of the glucocorticoid effect suggests that trehalase may not be a primary response gene.
Assuntos
Regulação da Expressão Gênica no Desenvolvimento , Intestino Delgado/enzimologia , Trealase/genética , Fatores Etários , Animais , Animais Lactentes , Dexametasona/administração & dosagem , Feminino , Intestino Delgado/embriologia , Intestino Delgado/crescimento & desenvolvimento , Masculino , Camundongos , Camundongos Endogâmicos C57BL , RNA/análise , RNA/metabolismo , RNA Mensageiro/análise , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ativação Transcricional/efeitos dos fármacos , Trealase/biossíntese , Trealase/metabolismoRESUMO
We report the construction and analysis of a mouse gene trap mutant resource created in the C57BL/6N genetic background containing more than 350,000 sequence-tagged embryonic stem (ES) cell clones. We also demonstrate the ability of these ES cell clones to contribute to the germline and produce knockout mice. Each mutant clone is identified by a genomic sequence tag representing the exact insertion location, allowing accurate prediction of mutagenicity and enabling direct genotyping of mutant alleles. Mutations have been identified in more than 10,000 genes and show a bias toward the first intron. The trapped ES cell lines, which can be requested from the Texas A&M Institute for Genomic Medicine, are readily available to the scientific community.