The intervening sequence of a mouse beta-globin gene is transcribed within the 15S beta-globin mRNA precursor.

Mouse beta-globin in encoded in a discontinuous structural gene interrupted by a 550-base pair intervening sequence of DNA. Correspondingly, the mature beta-globin mRNA appears to be synthesized via a 15S precursor, the length of which roughly equals the total length of the coding and intervening sequences of the beta-globin gene. Using the electron microscope to visualize hybrid structures formed between this gene and the purified 15S beta-globin mRNA precursor, we show that the intervening sequence is present within the larger precursor molecule. This finding suggests that the precursor mRNA is processed through the removal and rejoining of internal RNA sequences.     

KAI1 PNA探针的制备及其在胰腺癌中的应用

目的：制备DIG标记KAI1 RNA探针和分析KAI1基因在胰腺癌中的表达。方法：以线性KAI1基因DNA质粒为模板，采用体外转录法掺入DIG-11-UTP制备RNA探针，并通过化学发光法检测。应用该探针通过Northern blot对12例正常胰腺组织和30例原发性胰腺癌组织中的KAI1基因mRNA进行分析。结果：该方法标记的KAI1 RNA探针浓度?a1ng/цl时即可检测。Northern bolt分析发现25例无转移的胰腺癌中KAI1基因在2.4kb处存在明显的杂交信号，5例发生转移的晚期胰腺癌杂交信号较弱，正常胰腺组织中该基因的表达水平呈阴性或弱阳性。结论：本法标记的KAI1RNA探针灵敏度高，KAI1基因低表达与胰腺癌转移有关。     

Pancreatic expression of human insulin gene in transgenic mice.

We have investigated the possibility of obtaining integration and expression of a native human gene in transgenic mice. An 11-kilobase (kb) human chromosomal DNA fragment including the insulin gene (1430 base pairs) was microinjected into fertilized mouse eggs. This fragment was present in the genomic DNA of several developing animals. One transgenic mouse and its progeny were analyzed for expression of the foreign gene. Synthesis and release of human insulin was revealed by detection of the human C-peptide in the plasma and urine. Human insulin mRNA was found in pancreas but not in other tissues. These findings indicate that the 11-kb human DNA fragment carries the sequences necessary for tissue-specific expression of the insulin gene and the human regulatory sequences react to homologous signals in the mouse.     

The sequence and tissue expression of ovine renin.

The primary structure of the sheep renin precursor has been determined from its cDNA sequence. A library of cDNA clones was constructed from adrenalectomized sheep kidney poly(A)+ RNA and screened for sheep renin sequences with a cloned mouse renin cDNA probe. Of the 300,000 clones generated, 24 were hybridization positive and the nucleotide sequences of two of the longest clones were determined. These clones coded for the mature sheep renin protein and the 3'-untranslated sequence but did not extend to the amino-terminal region of preprorenin. Clones corresponding to the 5' region of renin mRNA were generated by the polymerase chain reaction and their nucleotide sequences determined. The sheep renin precursor consists of 400 amino acids with a putative leader sequence of 14 amino acids and a putative 45 or 53 amino acid prosegment. The mature sheep renin protein has a 73% sequence identity with human renin. Northern analysis demonstrated the presence of renin mRNA in the kidney but not in other tissues in the sheep. While sodium depletion of sheep caused a rise in renin mRNA in the kidney, adrenalectomy also led to a large increase in renal renin mRNA. Southern analysis of genomic DNA suggests that there is only one gene coding for renin in the sheep.