Spatial and temporal expression patterns of Bmal delineate a circadian clock in the nervous system of Branchiostoma lanceolatum.
We cloned the homologue of the clock gene Bmal from a cephalochordate, Branchiostoma lanceolatum (syn. amphioxus). Amphioxus possesses a single copy of this gene (amphiBmal) that encodes for a protein of 649 amino acids, which is quite similar to BMALs of other chordates. The gene is expressed by a restricted cell group in the anterior vesicle of the neural tube, and its expression site coincides with that of another clock gene, namely, amphiPer. The expression of amphiBmal shows a rhythmic fluctuation that persists under constant darkness and is, thus, circadian. Similar to the situation in craniates, the peak phases of the amphiBmal and amphiPer expression are offset by 12 hours. Based on these observations and the putative homology between the diencephalon of vertebrates and the anterior vesicle of lancelets, we suggest a homology between the suprachiasmatic nucleus of craniates and the amphiBmal/amphiPer-expressing cell group of amphioxus.
Fachbereich Medizin der Johann Wolfgang Goethe-Universität, Dr. Senckenbergische Anatomie, D-60590 Frankfurt, Germany.
Helmut
H
Wicht
Elke
E
Laedtke
Horst-Werner
HW
Korf
Christof
C
Schomerus
D056930:ARNTL Transcription Factors / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001683:Biological Clocks / Q000235:genetics*; D005075:Biological Evolution; D002816:Chordata, Nonvertebrate / Q000033:anatomy & histology / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics*; D003001:Cloning, Molecular; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009420:Nervous System; D010802:Phylogeny; D016548:Prosencephalon / Q000033:anatomy & histology / Q000502:physiology; D013493:Suprachiasmatic Nucleus / Q000033:anatomy & histology / Q000502:physiology
D056930:ARNTL Transcription Factors