Epigenetic Regulation by Long Noncoding RNAs Lee, Jeannie T.
Science (American Association for the Advancement of Science),
12/2012, Letnik:
338, Številka:
6113
Journal Article
Recenzirano
Recent studies show that transcription of the mammalian genome is not only pervasive but also enormously complex. It is estimated that an average of 10 transcription units, the vast majority of which ...make long noncoding RNAs (lncRNAs), may overlap each traditional coding gene. These lncRNAs include not only antisense, intronic, and intergenic transcripts but also pseudogenes and retrotransposons. Do they universally have function, or are they merely transcriptional by-products of conventional coding genes? A glimpse into the molecular biology of multiple emerging lncRNA systems reveals the "Wild West" landscape of their functions and mechanisms and the key problems to solve in the years ahead toward understanding these intriguing macromolecules.
Oxidative stress suppresses animal health, performance, and production, subsequently impacting economic feasibility; hence, maintaining and improving oxidative status especially through natural ...nutrition strategy are essential for normal physiological process in animals. Phytochemicals are naturally occurring antioxidants that could be considered as one of the most promising materials used in animal diets in various forms. In this review, their antioxidant effects on animals are discussed as reflected by improved apparent performance, productivity, and the internal physiological changes. Moreover, the antioxidant actions toward animals further describe a molecular basis to elucidate their underlying mechanisms targeting signal transduction pathways, especially through the antioxidant response element/nuclear factor (erythroid-derived 2)-like 2 transcription system.
The long noncoding Xist RNA inactivates one X chromosome in the female mammal. Current models posit that Xist induces silencing as it spreads along X and recruits Polycomb complexes. However, the ...mechanisms for Xist loading and spreading are currently unknown. Here, we define the nucleation center for Xist RNA and show that YY1 docks Xist particles onto the X chromosome. YY1 is a “bivalent” protein, capable of binding both RNA and DNA through different sequence motifs. Xist's exclusive attachment to the inactive X is determined by an epigenetically regulated trio of YY1 sites as well as allelic origin. Specific YY1-to-RNA and YY1-to-DNA contacts are required to load Xist particles onto X. YY1 interacts with Xist RNA through Repeat C. We propose that YY1 acts as adaptor between regulatory RNA and chromatin targets.
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► The inactive X nucleation center consists of three YY1 sites ► YY1 tethers Xist RNA to the nucleation center ► YY1 is bivalent, binding both RNA and DNA ► Xist RNA is diffusible and is trapped by the X chromosome via YY1
The localization of charge carriers by electronic repulsion was suggested by Mott in the 1930s to explain the insulating state observed in supposedly metallic NiO. The Mott metal-insulator transition ...has been subject of intense investigations ever since
-not least for its relation to high-temperature superconductivity
. A detailed comparison to real materials, however, is lacking because the pristine Mott state is commonly obscured by antiferromagnetism and a complicated band structure. Here we study organic quantum spin liquids, prototype realizations of the single-band Hubbard model in the absence of magnetic order. Mapping the Hubbard bands by optical spectroscopy provides an absolute measure of the interaction strength and bandwidth-the crucial parameters that enter calculations. In this way, we advance beyond conventional temperature-pressure plots and quantitatively compose a generic phase diagram for all genuine Mott insulators based on the absolute strength of the electronic correlations. We also identify metallic quantum fluctuations as a precursor of the Mott insulator-metal transition, previously predicted but never observed. Our results suggest that all relevant phenomena in the phase diagram scale with the Coulomb repulsion U, which provides a direct link to unconventional superconductivity in cuprates and other strongly correlated materials.
X chromosome inactivation and genomic imprinting are classic epigenetic processes that cause disease when not appropriately regulated in mammals. Whereas X chromosome inactivation evolved to solve ...the problem of gene dosage, the purpose of genomic imprinting remains controversial. Nevertheless, the two phenomena are united by allelic control of large gene clusters, such that only one copy of a gene is expressed in every cell. Allelic regulation poses significant challenges because it requires coordinated long-range control in cis and stable propagation over time. Long noncoding RNAs have emerged as a common theme, and their contributions to diseases of imprinting and the X chromosome have become apparent. Here, we review recent advances in basic biology, the connections to disease, and preview potential therapeutic strategies for future development.
Phytochemicals which exist in various plants and fungi are non-nutritive compounds that exert numerous beneficial bioactive actions for animals. In recent years following the restriction of ...antibiotics, phytochemicals have been regarded as a primal selection when dealing with the challenges during the producing process in the poultry industry. The selected fast-growing broiler breed was more fragile when confronting the stressors in their growing environments. The disruption of oxidative balance that impairs the production performance in birds may somehow be linked to the immune system since oxidative stress and inflammatory damage are multi-stage processes. This review firstly discusses the individual influence of oxidative stress and inflammation on the poultry industry. Next, studies related to the application of phytochemicals or botanical compounds with the significance of their antioxidant and immunomodulatory abilities are reviewed. Furthermore, we bring up nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and nuclear factor kappa B (NF-κB) for they are respectively the key transcription factors involved in oxidative stress and inflammation for elucidating the underlying signal transduction pathways. Finally, by the discussion about several reports using phytochemicals to regulate these transcription factors leading to the improvement of oxidative status, heme oxygenase-1 gene is found crucial for Nrf2-mediated NF-κB inhibition.
Tuning the magnetic properties of nanoparticles Kolhatkar, Arati G; Jamison, Andrew C; Litvinov, Dmitri ...
International Journal of Molecular Sciences,
07/2013, Letnik:
14, Številka:
8
Journal Article, Book Review
Recenzirano
Odprti dostop
The tremendous interest in magnetic nanoparticles (MNPs) is reflected in published research that ranges from novel methods of synthesis of unique nanoparticle shapes and composite structures to a ...large number of MNP characterization techniques, and finally to their use in many biomedical and nanotechnology-based applications. The knowledge gained from this vast body of research can be made more useful if we organize the associated results to correlate key magnetic properties with the parameters that influence them. Tuning these properties of MNPs will allow us to tailor nanoparticles for specific applications, thus increasing their effectiveness. The complex magnetic behavior exhibited by MNPs is governed by many factors; these factors can either improve or adversely affect the desired magnetic properties. In this report, we have outlined a matrix of parameters that can be varied to tune the magnetic properties of nanoparticles. For practical utility, this review focuses on the effect of size, shape, composition, and shell-core structure on saturation magnetization, coercivity, blocking temperature, and relaxation time.
It appears inevitable that severe acute respiratory syndrome coronavirus 2 will continue to spread. Although we still have limited information on the epidemiology of this virus, there have been ...multiple reports of superspreading events (SSEs), which are associated with both explosive growth early in an outbreak and sustained transmission in later stages. Although SSEs appear to be difficult to predict and therefore difficult to prevent, core public health actions can prevent and reduce the number and impact of SSEs. To prevent and control of SSEs, speed is essential. Prevention and mitigation of SSEs depends, first and foremost, on quickly recognizing and understanding these events, particularly within healthcare settings. Better understanding transmission dynamics associated with SSEs, identifying and mitigating high-risk settings, strict adherence to healthcare infection prevention and control measures, and timely implementation of nonpharmaceutical interventions can help prevent and control severe acute respiratory syndrome coronavirus 2, as well as future infectious disease outbreaks.
We simulate the growth of a Population III stellar system, starting from cosmological initial conditions at z = 100. We follow the formation of a minihalo and the subsequent collapse of its central ...gas to high densities, resolving scales as small as ∼ 1 au. Using sink particles to represent the growing protostars, we model the growth of the photodissociating and ionizing region around the first sink, continuing the simulation for ∼5000 yr after initial protostar formation. Along with the first-forming sink, several tens of secondary sinks form before an ionization front develops around the most massive star. The resulting cluster has high rates of sink formation, ejections from the stellar disc, and sink mergers during the first ∼ 2000 yr, before the onset of radiative feedback. By this time, a warm ∼5000 K phase of neutral gas has expanded to roughly the disc radius of 2000 au, slowing mass flow on to the disc and sinks. By 5000 yr the most massive star grows to 20 M⊙, while the total stellar mass approaches 75 M⊙. Out of the ∼ 40 sinks, approximately 30 are low mass (M
* < 1 M⊙), and if the simulation had resolved smaller scales an even greater number of sinks might have formed. Thus, protostellar radiative feedback is insufficient to prevent rapid disc fragmentation and the formation of a high-member Pop III cluster before an ionization front emerges. Throughout the simulation, the majority of stellar mass is contained within the most massive stars, further implying that the Pop III initial mass function is top-heavy.
Tropospheric ozone (O
) is a key component of air pollution and an important anthropogenic greenhouse gas
. During the twentieth century, the proliferation of the internal combustion engine, rapid ...industrialization and land-use change led to a global-scale increase in O
concentrations
; however, the magnitude of this increase is uncertain. Atmospheric chemistry models typically predict
an increase in the tropospheric O
burden of between 25 and 50 per cent since 1900, whereas direct measurements made in the late nineteenth century indicate that surface O
mixing ratios increased by up to 300 per cent
over that time period. However, the accuracy and diagnostic power of these measurements remains controversial
. Here we use a record of the clumped-isotope composition of molecular oxygen (
O
O in O
) trapped in polar firn and ice from 1590 to 2016 AD, as well as atmospheric chemistry model simulations, to constrain changes in tropospheric O
concentrations. We find that during the second half of the twentieth century, the proportion of
O
O in O
decreased by 0.03 ± 0.02 parts per thousand (95 per cent confidence interval) below its 1590-1958 AD mean, which implies that tropospheric O
increased by less than 40 per cent during that time. These results corroborate model predictions of global-scale increases in surface pollution and vegetative stress caused by increasing anthropogenic emissions of O
precursors
. We also estimate that the radiative forcing of tropospheric O
since 1850 AD is probably less than +0.4 watts per square metre, consistent with results from recent climate modelling studies
.
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