Search results for "clock"

Rhythmicity of Intestinal IgA Responses Confers Oscillatory Commensal Microbiota Mutualism

2021

ABSTRACTMutualistic interactions with the commensal microbiota are enforced through a range of immune responses that confer metabolic benefits for the host and ensure tissue health and homeostasis. Immunoglobulin (Ig)A responses directly determine the composition of commensal species that colonize the intestinal tract but require significant metabolic resources to fuel antibody production by tissue-resident plasma cells. Here we demonstrate IgA responses are subject to diurnal regulation by dietary-derived metabolic cues and a cell-intrinsic circadian clock. Rhythmicity in IgA secretion conferred oscillatory patterns on the commensal microbial community and its associated metabolic activity…

Oscillatory Dynamics Underlying Perceptual Narrowing of Native Phoneme Mapping from 6 to 12 Months of Age

2016

During the first months of life, human infants process phonemic elements from all languages similarly. However, by 12 months of age, as language-specific phonemic maps are established, infants respond preferentially to their native language. This process, known as perceptual narrowing, supports neural representation and thus efficient processing of the distinctive phonemes within the sound environment. Although oscillatory mechanisms underlying processing of native and non-native phonemic contrasts were recently delineated in 6-month-old infants, the maturational trajectory of these mechanisms remained unclear. A group of typically developing infants born into monolingual English families, …

Nanoseconds Timing System Based on IEEE 1588 FPGA Implementation

2019

Clock synchronization procedures are mandatory in most physical experiments where event fragments are readout by spatially dislocated sensors and must be glued together to reconstruct key parameters (e.g. energy, interaction vertex etc.) of the process under investigation. These distributed data readout topologies rely on an accurate time information available at the frontend, where raw data are acquired and tagged with a precise timestamp prior to data buffering and central data collecting. This makes the network complexity and latency, between frontend and backend electronics, negligible within upper bounds imposed by the frontend data buffer capability. The proposed research work describ…

Genome-wide association studies identify 137 genetic loci for DNA methylation biomarkers of aging

2021

Abstract Background Biological aging estimators derived from DNA methylation data are heritable and correlate with morbidity and mortality. Consequently, identification of genetic and environmental contributors to the variation in these measures in populations has become a major goal in the field. Results Leveraging DNA methylation and SNP data from more than 40,000 individuals, we identify 137 genome-wide significant loci, of which 113 are novel, from genome-wide association study (GWAS) meta-analyses of four epigenetic clocks and epigenetic surrogate markers for granulocyte proportions and plasminogen activator inhibitor 1 levels, respectively. We find evidence for shared genetic loci ass…

Identification and characterization of circadian clock genes in the pea aphid Acyrthosiphon pisum

2010

The molecular basis of circadian clocks is highly evolutionarily conserved and has been best characterized in Drosophila and mouse. Analysis of the Acyrthosiphon pisum genome revealed the presence of orthologs of the following genes constituting the core of the circadian clock in Drosophila: period (per), timeless (tim), Clock, cycle, vrille, and Pdp1. However, the presence in A. pisum of orthologs of a mammal-type in addition to a Drosophila-type cryptochrome places the putative aphid clockwork closer to the ancestral insect system than to the Drosophila one. Most notably, five of these putative aphid core clock genes are highly divergent and exhibit accelerated rates of change (especially…

Phylogeny of Polycnemoideae (Amaranthaceae): Implications for biogeography, character evolution and taxonomy

2013

Ancient or recent? Insights into the temporal evolution of the Bruniaceae

2008

AbstractThe Bruniaceae are a South African plant family endemic to the Cape Floristic Region with one geographic outlier (Raspalia trigyna) in the Natal Province. Recent molecular phylogenetic analyses have cast new light upon inter- and intra-generic relationships within the family. The present work uses those data to gain insights into the temporal evolution of Bruniaceae by inferring a molecular clock. For calibration, the inferred age of Berzelia cordifolia (3–5My) was used, based on its distribution restricted to the geologically young limestone area around Bredasdorp. The results are consistent with the purported Cretaceous age of the family (‘palaeoendemics’), but also suggest that m…

Melastomeae come full circle: biogeographic reconstruction and molecular clock dating.

2001

Rhexia, with 11 species in the Coastal Plain province of North America, is the only temperate zone endemic of the tropical eudicot family Melastomataceae. It is a member of the only pantropical tribe of that family, Melastomeae. Based on the chloroplast gene ndhF, we use a fossil-calibrated molecular clock to address the question of the geographic origin and age of Rhexia. Sequences from 37 species in 21 genera representing the tribe's geographical range were analyzed together with five outgroups. To obtain better clade support, another chloroplast region, the rpl16 intron, was added for 24 of the species. Parsimony analysis of the combined data and maximum-likelihood analysis of ndhF alone…

Evidence for a dysfunction and disease-promoting role of the circadian clock in the diabetic retina.

2021

Diabetic retinopathy is a major complication of chronic hyperglycemia and a leading cause of blindness in developed countries. In the present study the interaction between diabetes and retinal clocks was investigated in mice. It was seen that in the db/db mouse - a widely used animal model of diabetic retinopathy - clock function and circadian regulation of gene expression was disturbed in the retina. Remarkably, elimination of clock function by Bmal1-deficiency mitigates the progression of pathophysiology of the diabetic retina. Thus high-fat diet was seen to induce histopathology and molecular markers associated with diabetic retinopathy in wild type but not in Bmal1-deficient mice. The d…

Direct detection of the 229Th nuclear clock transition

2017

Today’s most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of 229Th (denoted 229mTh). Here we report the direct detection of this nuclear state, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters. On the basis of this direct detection, the isomeric energy is const…