Circadian rhythm of period gene and protein Jeffrey C. Hall

1 circadian rhythm of period gene , protein

1.1 discovery of per protein self regulation
1.2 discovery of synchronization between cells
1.3 refining transcription-translation negative feedback loop model

circadian rhythm of period gene , protein

hall worked drosophila study mechanism of circadian rhythms. rather using more traditional method of measuring eclosion, hall measured locomotor activity of drosophila observe circadian rhythms.

discovery of per protein self regulation

in 1990, while in collaboration michael rosbash , paul hardin, hall discovered period protein (per) played role in suppressing own transcription. while exact role of per unknown, hall, rosbash, , hardin able develop negative transcription-translation feedback loop model (ttfl) serves central mechanism of circadian clock in drosophila. in original model, per expression led increase of per. after concentration of per, expression of per decreased, causing per levels decrease, once again allowing per expressed.

discovery of synchronization between cells

in 1997, hall part of group susan renn, jae park, michael rosbash, , paul taghert discovered genes part of ttfl expressed in cells throughout body. despite these genes being identified necessary genes circadian clock, there variety of levels of expressions in various parts of body; variation observed on cellular level. hall succeeded in entraining separate tissues different light-dark cycles @ same time. hall didn t discover element synchronizes cells until 2003. found pigment dispersing factor protein (pdf) helps control circadian rhythms, , in turn locomotor activity, of these genes in cells. localized small ventral lateral neurons (slnvs) in drosophila brain. data, hall concluded slnvs serve primary oscillator in drosophila , pdf allows synchrony between cells. awarded 2017 nobel prize in medicine or physiology.

refining transcription-translation negative feedback loop model

in 1998, hall contributed 2 discoveries in drosophila refined ttfl model. first discovery involved role cryptochrome (cry) plays in entrainment. hall found cry key photoreceptor both entrainment , regulation of locomotor activity. hypothesized cry may not input circadian system, role pacemaker itself. in same year, hall discovered how drosophila per , timeless (tim) circadian genes regulated. hall discovered clock , cycle (cyc) proteins form heterodimer via pas domain. upon dimerizing, 2 proteins bind e box promoter element of 2 genes via bhlh domain induce expression of per , tim mrna.