The mammalian circadian system is comprised of a central clock in the suprachiasmatic nucleus (SCN) and a network of peripheral oscillators located in all of the major organ systems. The SCN is traditionally thought to be positioned at the top of the hierarchy, with SCN lesions resulting in an arrhythmic organism. However, recent work has demonstrated that the SCN and peripheral tissues generate independent circadian oscillations in Per1 clock gene expression in vitro. In the present study, we sought to clarify the role of the SCN in the intact system by recording rhythms in clock gene expression in vivo. A practical imaging protocol was developed that enables us to measure circadian rhythms easily, noninvasively, and longitudinally in individual mice. Circadian oscillations were detected in the kidney, liver, and submandibular gland studied in about half of the SCN-lesioned, behaviorally arrhythmic mice. However, their amplitude was decreased in these organs. Free-running periods of peripheral clocks were identical to those of activity rhythms recorded before the SCN lesion. Thus, we can report for the first time that many of the fundamental properties of circadian oscillations in peripheral clocks in vivo are maintained in the absence of SCN control.
Perturbation in the energy‐transfer pathway and of the π conjugation between the chromophores in a triarylborane–porphyrin conjugate on coordination of a fluoride ion to the boron center is assumed to account for the observation of the three emission bands (at 356, 670, and 692 nm). The system also displays a colorimetric (purple to green, see picture, and red to bluish emission) response to fluoride ions.
Peripheral circadian clocks in mammals are strongly entrained by light-dark and eating cycles. Their physiological functions are maintained by the synchronization of the phase of organs via clock gene expression patterns. However, little is known about the adaptation of peripheral clocks to the timing of multiple daily meals. Here, we investigated the effect of irregular eating patterns, in terms of timing and volume, on their peripheral clocks in vivo. We found that the phase of the peripheral clocks was altered by the amount of food and the interval between feeding time points but was unaffected by the frequency of feeding, as long as the interval remained fixed. Moreover, our results suggest that a late dinner should be separated into 2 half-dinners in order to alleviate the effect of irregular phases of peripheral clocks.
Low-frequency square-wave modulation of a rf discharge in silane diluted with a rare gas brought about an improvement in the deposition rate of amorphous hydrogenated silicon films and in the film quality as well as a drastic suppression of powder concentration in the discharge space. These results can be explained by a SiH3 density in the modulated discharge that is high compared to that without modulation, because of the electron density enhancement resulting from the modulation and also because the lifetime of SiH3 radicals is much longer than those of SiHn radicals (n=0–2).
SummarySpinal muscular atrophy (SMA) is a common neuromuscular disorder with autosomal recessive inheritance, resulting in the degeneration of motor neurons. The incidence of the disease has been estimated at 1 in 6000-10,000 newborns with a carrier frequency of 1 in 40-60. SMA is caused by mutations of the SMN1 gene, located on chromosome 5q13. The gene product, survival motor neuron (SMN) plays critical roles in a variety of cellular activities. SMN2, a homologue of SMN1, is retained in all SMA patients and generates low levels of SMN, but does not compensate for the mutated SMN1. Genetic analysis demonstrates the presence of homozygous deletion of SMN1 in most patients, and allows screening of heterozygous carriers in affected families. Considering high incidence of carrier frequency in SMA, population-wide newborn and carrier screening has been proposed. Although no effective treatment is currently available, some treatment strategies have already been developed based on the molecular pathophysiology of this disease. Current treatment strategies can be classified into three major groups: SMN2-targeting, SMN1-introduction, and non-SMN targeting. Here, we provide a comprehensive and up-to-date review integrating advances in molecular pathophysiology and diagnostic testing with therapeutic developments for this disease including promising candidates from recent clinical trials.
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