The timeless mutation (tim) leads to loss of circadian behavioral rhythms in Drosophila melanogaster. The effects of tim on rhythmicity involve interactions with period (per), a second essential clock gene, as the tim mutation suppresses circadian oscillations of per transcription and blocks nuclear localization of a PER reporter protein. In the present study it was found that the tim mutant co...

Whether every effect can be precisely linked to a given cause or to a list of causes has been a matter of debate for centuries, particularly during the 17th century, when astronomers became capable of predicting the trajectories of planets. Recent mathematical models applied to physics have included the idea that given phenomena cannot be predicted precisely, although they can be predicted to s...

The hypothesis suggesting that the blastocoele is able to form only at a definite nucleocytoplasmic ratio was tested. We compared the development of preimplantation mouse embryos under different conditions. The results demonstrated that the start of cavitation is not dependent on the number of cell divisions. Thus, a definite nucleocytoplasmic ratio is not required for blastocoele formation to ...

Mutants affecting the period length of the biological clock in Chlamydomonas reinhardi have been isolated and a start has been made on analyzing the genetics of this system. In four mutants, the long period characteristic seems to be controlled by single genes at separate loci. Crosses between single mutants, as well as crosses involving three or four mutant genes, yielded progeny with periods ...

Life on earth has evolved on a photic carousel, spinning through alternating periods of light and darkness. This playful image belies the fact that only those organisms that learned how to benefit from the recurring features in their environment were allowed to ride on. This selection process has engendered many daily rhythms in our biosphere, most of which rely on the anticipatory power of an ...

The molecular clock presents a means of estimating evolutionary rates and timescales using genetic data. These estimates can lead to important insights into evolutionary processes and mechanisms, as well as providing a framework for further biological analyses. In order to deal with rate variation among genes and among lineages, a diverse range of molecular-clock models have been developed. The...

The clock comparison experiments to test special relativity mainly include the Michelson–Morley experiment, Kennedy–Thorndike Ives–Stilwell experiment and of atomic clocks in two locations. These can be roughly classified as types clocks: optical clocks. Through such clocks, Lorentz invariance breaking parameters RMS framework tested. However, experiments, structural effects have been fully con...

Human sleep-wake cycles are entrained by both natural and artificial light-dark cycles. However, little is known regarding when and how the photoperiod changes entrain the biological clock after conception. To investigate the dependence of sleep patterns in young infants on the natural and artificial light-dark cycles, 1,302 pairs of one-month-old infants and their mothers were asked to answer ...

BACKGROUND Alteration of circadian rhythmicity with aging might depend on physical aerobic capacity. METHODS Three groups of participants were established based on their peak oxygen consumption (Group 1 < 20mL/min/kg; Group 2 > 20mL/min/kg and <30mL/min/kg; Group 3 > 30mL/min/kg). Each participant had an individual evaluation of their circadian rhythmicity characteristics through two well-kno...