Biomedical subjects

Betsy Dobbs-McAuliffe

Publications and source records attributed to Betsy Dobbs-McAuliffe.

3 recordsLinked to original sources

PubMed2005

Expression of cyp26b1 during zebrafish early development.

We have cloned the zebrafish ortholog of the mammalian cyp26b1 gene. The predicted zebrafish cyp26b1 protein shares greater than 73% identity with mammalian homologues. cDNA transfection assays showed that like human cyp26b1, zebrafish cyp26b1 is involved in limiting the activity of retinoic acid. Reverse transcription-polymerase chain reaction (RT-PCR) analysis of embryonic RNAs suggested that no maternal cyp26b1 message is detectable. Zygotic cyp26b1 message could be detected at 75% epiboly by RT-PCR and localized to presumptive rhombomere 3 and rhombomere 4 at the early two-somite (2S) stage (10.5 hpf: hour post fertilization) by whole mount in situ hybridization. As development proceeds expression expands anteriorly to include rhombomere 2 at the 10S stage (14hpf). By 14S (16hpf) expression in the hindbrain has also expanded posteriorly and encompasses rhombomere 2 through rhombomere 6. At later stages, 24 through 48 hpf, additional expression was found in the eyes, diencephalon, midbrain-hindbrain boundary, cerebellum, pectoral fin and the pharyngeal arch primordia.

Amino Acid Sequence↗

PubMed2004

Microarray gene expression profiling during the segmentation phase of zebrafish development.

We analyzed 15,512 unique transcripts from wild-type Danio rerio using a long oligonucleotide microarray containing >16,000 65-mers probes. Total RNA was isolated from staged embryos at 2 h intervals over a 24-h period. On average, at any given time point, 27% of the probe set detected corresponding transcripts in embryonic RNA. There were two predominant patterns in the nearly 4000 genes that changed expression in at least one time point during the first 24 hpf. At 12 hpf, we detected 420 up-regulated and 386 down-regulated genes. By 24 hpf, the number of up- and down-regulated genes had increased to 954 and 766, respectively. While the majority of these genes maintained their new level of expression for the duration of the time course, we identified five genes with phasic regulation over the 24-h time course. Two of these genes, germ cell nuclear factor and mesogenin, have been identified as being expressed during gastrulation (5 1/4 to 10 h postfertilization) and subsequently repressed. A cluster containing 36 distinct ribosomal proteins was up-regulated at 12 h, indicating a capability for de novo protein synthesis during and after this stage. Twenty-three muscle-specific genes were up-regulated late during the initial 24 hpf, corresponding to the development and differentiation of the somites.

Animals↗

PubMed2004

Feedback mechanisms regulate retinoic acid production and degradation in the zebrafish embryo.

Retinoic acid (RA) signaling in vertebrate embryos occurs in a distinct physical and temporal pattern. Regulating this spatial distribution is crucial to the development of the embryo, as RA in excess or in inappropriate tissues is teratogenic. In order to understand how RA availability is determined in zebrafish we have investigated the expression of cyp26a1, an enzyme that inactivates RA, and its relationship to raldh2, one of the enzymes that produce RA from retinal. cyp26a1 expression follows three phases: in presumptive anterior neurectoderm and in a circumblastoporal ring during gastrulation, in the tailbud throughout somitogenesis, and in multiple specific tissue types beginning at mid-somitogenesis and continuing through 48 h postfertilization (hpf). This expression was either adjacent or opposite to those tissues expressing raldh2. We then investigated how RA production might regulate these relationships. Endogenous RA produced by raldhs did not play a role in setting cyp26a1 expression in most tissues. However, exogenous RA regulates expression of both enzymes. cyp26a1 is up regulated in the embryo in a time, concentration, and tissue-dependent manner. Conversely, raldh2 expression is reduced with RA treatment. Tests of the raldh2 promoter in cell transfections proved that RA directly represses its activity. These data demonstrate that the feedback mechanisms regulating production and degradation of RA must be considered in any experiments altering levels of RA in the developing vertebrate embryo.

Aldehyde Oxidoreductases↗