Individual differences in cortisol responses to a laboratory speech task and their relationship to responses to stressful daily events.

A Stress Inducing Speech Task was used to investigate the contribution of perceived stress, individual traits, and current mood states to individual differences in salivary cortisol responses. Additionally, we examined the correspondence between laboratory baseline cortisol levels and overall levels in daily life, and between cortisol responses to the speech task and a measure of stress reactivity to stressful events in daily life. Forty-two 'high stress' and forty-five 'low stress' white-collar males completed the speech task and an Experience Sampling study, in which stressful daily events and cortisol levels were monitored for five days. No association was found between perceived stress, trait anxiety, anger, depression, psychosomatic symptoms, coping style or personality and cortisol responses to the speech task. Negative mood state at baseline was associated with higher cortisol levels at baseline just before, and just after, the speech. Laboratory and field cortisol levels were moderately correlated, but no association was found between laboratory and field response measures. Laboratory baseline levels, but not responses to the speech task, were significant predictors of field cortisol levels.

The mouse apolipoprotein C1 gene: structure and expression.

We have isolated and characterized cDNA and genomic clones containing the mouse apolipoprotein C1 (Apoc1) gene. The Apoc1 gene is part of the Apoe-c1-c2 gene cluster and is located 3.4 kb 3' of the Apoe gene. The mouse Apoc1 gene spans a region of approximately 3.3 kb and consists of four exons. The exon-intron structure is similar to those of human and baboon genes, although in mouse introns 2 and 3 are smaller. Significant sequence homology is found between man and mouse in the promoter and exonic regions (80 and 67%, respectively). Northern blotting and primer extension analysis of mouse RNA showed that a major transcript 409 bp in size is expressed primarily in fetal and adult liver. The mouse Apoc1 cDNA contains an open reading frame encoding a protein of 88 amino acids, including a signal peptide of 26 amino acid residues. Comparisons of the deduced amino acid sequence of mouse apoC1 with the human, baboon, rat, and dog sequences showed discrete regions with a high degree of conservation. The delineation of the sequence and structural organization of the mouse Apoc1 gene is an essential step in enhancing the use of mouse models to study the function of apoC1 in the lipoprotein metabolism.

The apolipoprotein C2-linked (Acl) gene: a new gene within the mouse apolipoprotein e-c1-c2 gene cluster.

The apolipoprotein E, C1, and C2 genes are contained within a gene cluster in man. Previously, we have shown that this gene cluster has a similar structure in mouse. During the characterization of the mouse Apoc2 gene, evolutionarily conserved and transcribed sequences were found 5' of the Apoc2 gene. In this study, we have shown that these 5' sequences represent a novel gene within the gene cluster designated the apolipoprotein C2-linked gene (Acl). The Acl gene is located 2 kb 5' to the Apoc2 gene. The transcriptional orientation is identical to that of the other genes within the Apoe-c1-c2 gene cluster. We have sequenced the mouse Acl gene at the cDNA and the genomic levels. The gene is composed of three exons spanning a region of approximately 3.6 kb. The Acl gene is expressed in the liver as a transcript 473 bp in size and encodes a putative protein of 124 amino acid residues.

Evolutionary conservation of the mouse apolipoprotein e-c1-c2 gene cluster: structure and genetic variability in inbred mice.

The human apolipoprotein E (APOE), APOC1, pseudo APOC1 (APOC1'), and APOC2 genes are clustered within 48 kb on the long arm of chromosome 19. A mouse Apoe cDNA probe was used to isolate overlapping cosmid clones from a cosmid library of the C57BL/Rij inbred mouse strain. These clones were investigated for the presence of the Apoc1 and Apoc2 genes by heterologous hybridization. Our results show that the Apoe-c1-c2 gene cluster is conserved in the mouse. In line with evolutionary data, the mouse lacks the equivalent of APOC1'. These data were confirmed using a mouse Apoc2 cDNA clone, and surprisingly the cDNA clone isolated here was 965 bp in size, which is on average 450 bp longer than other APOC2 cDNAs described so far. Correspondingly, the Apoc2 gene occupies an unusually large genomic region, due to an extended 5' end. Interestingly, a variable number of tandem repeat (VNTR) in the third intron of the human APOC2 gene shows a high sequence homology and is located at the identical position in the mouse gene. Despite the high copy number of this VNTR (27 or 34 copies) only two variants were found among 11 different inbred strains. With the aid of six restriction fragment length variations in this gene cluster only two different haplotypes could be deduced, indicating that the Apoe-c1-c2 gene cluster is highly conserved in the inbred strains that were studied.

Structure and expression of the mouse apolipoprotein C2 gene.

Three cDNA clones containing the mouse apolipoprotein C2 (Apoc2) gene were isolated from a mouse liver cDNA library. The inserts from two cDNA clones were 500 bp in size while the insert from the third clone was unexpectedly large, 962 bp. All three clones contained a single open reading frame encoding apoC2. The exon-intron structure of the mouse Apoc2 gene was determined by sequence analysis. Northern blotting and primer extension analysis of mouse RNA showed that the major liver transcript is 500 bp in size and is encoded by four exons. Transcripts for Apoc2 were found in fetal liver, adult liver, intestine, and peritoneal macrophages. The largest cDNA clone, mAPOC2c4, contained an additional 440 bp at the 5' end that are evolutionary conserved between man and mouse. These additional sequences are encoded by two exons located 5' to the major liver start site. Although the larger transcript could not be detected by Northern blot analysis, products resulting from an upstream transcription initiation site were detected in the liver using RT-PCR analysis. The sizes of the RT-PCR products are consistent with alternative splicing.

The mouse low density lipoprotein receptor gene: cDNA sequence and exon-intron structure.

The low density lipoprotein (LDL) receptor plays a central role in the cholesterol metabolism. The cDNA sequence of the mouse low density lipoprotein receptor (Ldlr) gene has been determined and shows 76% homology with the human gene. The exon-intron structure has been determined for the 129/J mouse strain. The gene is composed of 18 exons and spans a region of 28 kb. In addition, the promoter regions of the mouse and human genes are homologous. Northern blot analysis revealed an mRNA of approximately 5 kb. The cloning of the Ldlr gene will enhance the usefulness of the mouse for the study of cholesterol metabolism and, in particular, for carrying out gene targeting experiments.