Disease relevance of Biological Clocks

• Therefore, we conclude that rpoD2 is a component of an output pathway of the biological clock that affects the circadian expression of a subset of genes in Synechococcus [1].
• Because the hosts of APSE-1 and HK620 have been separated from each other by an estimated 200 My, we propose using the amino acid differences that have accumulated in these proteins to estimate a biological clock for temperate lambdoid phages.The putative transcriptional regulatory gene circuitry of HK620 seems to resemble that of phage lambda [2].
• Possible involvement of light regulated gonadotropin-releasing hormone neurons in biological clock for reproduction in the cerebral ganglion of the ascidian, Halocynthia roretzi [3].
• Dysregulation of photic induction of Fos-related protein in the biological clock during experimental trypanosomiasis [4].
• Our objective was to determine whether enhancement of the functioning of the biological clock by repeated nighttime melatonin intake might reduce ambulatory blood pressure in patients with essential hypertension [5].

Psychiatry related information on Biological Clocks

• The daily rhythm in plasma glucagon concentrations in the rat is modulated by the biological clock and by feeding behavior [6].
• We investigated the daily profile of serum melatonin levels in patients with dementia of the Alzheimer's type (AD), since daily melatonin rhythm is thought to reflect the functioning of the biological clock [7].

High impact information on Biological Clocks

• Mutations in ELA2, encoding neutrophil elastase, define a 21-day biological clock in cyclic haematopoiesis [8].
• The expression of the Clock gene in zebrafish shows a strong circadian oscillation in many tissues in vivo and in culture, showing that endogenous oscillators exist in peripheral organs [9].
• The mammalian proteins Cryl and Cry2, which are members of the family of plant blue-light receptors (cryptochromes) and photolyases, have been proposed as candidate light receptors for photoentrainment of the biological clock [10].
• The mechanism of the 'biological clock' which regulates these variations in level of chick pineal NAT activity is unknown [11].
• The mCry double-mutant mice retain the ability to have mPer1 and mPer2 expression induced by a brief light stimulus known to phase-shift the biological clock in wild-type animals [12].

Biological context of Biological Clocks

• Decreased vasopressin gene expression in the biological clock of Alzheimer disease patients with and without depression [13].
• Biorhythms, such as regular variation in core body temperature and the pattern of the secretion of melatonin, are thought to be mediated by the same biological clock [14].
• Increasing evidence suggests an important role for VPAC2-activated signal transduction pathways in maintaining a synchronized biological clock in the suprachiasmatic nucleus (SCN) [15].
• Diurnal changes in liver TR alpha 1 and TR alpha 2 are controlled by the biological clock in the SCN but not via changes in the daily rhythm of food intake [16].
• It was concluded that grafted Brattleboro fetal suprachiasmatic nucleus develop their intrinsic rhythm conform their genotype and that vasopressin is not a crucial component in the maintenance nor in the transfer of circadian activity of the biological clock for drinking activity [17].

Anatomical context of Biological Clocks

• Ontogenesis of a biological clock for serotonin:acetyl coenzyme A N-acetyltransferase in pineal gland of rat [18].
• The paper by Hirata et al.(1) identifies a biological clock in cultured cells that is dependent upon the Notch target gene Hes1, and which shows a periodicity similar to that of the segmentation clock [19].
• Plasma glucose concentrations display a daily rhythm generated by the hypothalamic biological clock, located in the suprachiasmatic nucleus (SCN) [6].
• To determine if ECTO-NOX proteins might represent the ultradian time keepers (pacemakers) of the biological clock, COS cells were transfected with cDNAs encoding tNOX proteins having a period length of 22 min or with C575A or C558A cysteine to alanine replacements having period lengths of 36 or 42 min [20].
• The Cryptochrome (Cry) genes found in animals and plants act both as photoreceptors and as essential components of the negative feedback mechanism of the biological clock [21].

Associations of Biological Clocks with chemical compounds

• Putative melatonin receptors in a human biological clock [22].
• Resetting the biological clock: mediation of nocturnal circadian shifts by glutamate and NO [23].
• Furthermore, we speculate that histamine receptors are the final gate at which both photic and non-photic entrainment mechanisms converge before sending a resetting signal to the intracellular biological clock [24].
• The existence of an activatable dopamine system within the hypothalamic suprachiasmatic nuclei (SCN), the site of a biological clock, was investigated in rats during fetal life [25].
• Cyclic AMP increases the expression of serotonin N-acetyltransferase and of inducible cAMP early repressor that undergo circadian oscillations crucial for the maintenance and regulation of the biological clock [26].

Gene context of Biological Clocks

• Here we report that nuclear translocation of mPER1 and mPER2 (1) involves physical interactions with mPER3, (2) is accelerated by serum treatment, and (3) still occurs in mCry1/mCry2 double-deficient cells lacking a functional biological clock [27].
• N-methyl-D-aspartate receptor subtype 2C is not involved in circadian oscillation or photoic entrainment of the biological clock in mice [28].
• The present results suggest that NR2A plays a weak role in oscillation or entrainment of the biological clock, and that NR2C does not participate in the functions of circadian oscillation and light entrainment [28].
• Here we propose that the circadian waves of the APRR1/TOC1 family members are most likely a molecular basis of such a biological clock in higher plants [29].
• Since it is known that these rats show a light-induced behavioral phase-shift throughout the subjective night with being strongest at subjective dawn, the present results suggest that the transient induction of Per1 in ventrolateral SCN neurons is a critical step in the resetting of the biological clock to environmental light-dark schedule [30].

Analytical, diagnostic and therapeutic context of Biological Clocks

• Our results suggest that melatonin administration to patients in intensive care units may be indicated as a treatment for sleep induction and resynchronization of the "biologic clock." This treatment may also help in the prevention of the "ICU syndrome" and accelerate the healing process [31].

References