Elucidating relationships among early animal lineages has been difficult, and recent phylogenomic analyses place Ctenophora sister to all other extant animals, contrary to the traditional view of ...Porifera as the earliest-branching animal lineage. To date, phylogenetic support for either ctenophores or sponges as sister to other animals has been limited and inconsistent among studies. Lack of agreement among phylogenomic analyses using different data and methods obscures how complex traits, such as epithelia, neurons, and muscles evolved. A consensus view of animal evolution will not be accepted until datasets and methods converge on a single hypothesis of early metazoan relationships and putative sources of systematic error (e.g., long-branch attraction, compositional bias, poormodel choice) are assessed. Here, we investigate possible causes of systematic error by expanding taxon sampling with eight novel transcriptomes, strictly enforcing orthology inference criteria, and progressively examining potential causes of systematic error while using both maximum-likelihood with robust data partitioning and Bayesian inference with a site-heterogeneous model. We identified ribosomal protein genes as possessing a conflicting signal compared with other genes, which caused some past studies to infer ctenophores and cnidarians as sister. Importantly, biases resulting from elevated compositional heterogeneity or elevated substitution rates are ruled out. Placement of ctenophores as sister to all other animals, and sponge monophyly, are strongly supported under multiple analyses, herein.
Two enigmatic groups of morphologically simple parasites of invertebrates, the Dicyemida (syn. Rhombozoa) and the Orthonectida, since the 19th century have been usually considered as two classes of ...the phylum Mesozoa. Early molecular evidence suggested their relationship within the Spiralia (=Lophotrochozoa), however, high rates of dicyemid and orthonectid sequence evolution led to contradicting phylogeny reconstructions. Genomic data for orthonectids revealed that they are highly simplified spiralians and possess a reduced set of genes involved in metazoan development and body patterning. Acquiring genomic data for dicyemids, however, remains a challenge due to complex genome rearrangements including chromatin diminution and generation of extrachromosomal circular DNAs, which are reported to occur during the development of somatic cells. We performed genomic sequencing of one species of
, and obtained transcriptomic data for two
spp. Homeodomain (homeobox) transcription factors, G-protein-coupled receptors, and many other protein families have undergone a massive reduction in dicyemids compared to other animals. There is also apparent reduction of the bilaterian gene complements encoding components of the neuromuscular systems. We constructed and analyzed a large dataset of predicted orthologous proteins from three species of
and a set of spiralian animals including the newly sequenced genome of the orthonectid
. Bayesian analyses recovered the orthonectid lineage within the Annelida. In contrast, dicyemids form a separate clade with weak affinity to the Rouphozoa (Platyhelminthes plus Gastrotricha) or (Entoprocta plus Cycliophora) suggesting that the historically proposed Mesozoa is a polyphyletic taxon. Thus, dramatic simplification of body plans in dicyemids and orthonectids, as well as their intricate life cycles that combine metagenesis and heterogony, evolved independently in these two lineages.
We considered features of registration of a nuclear magnetic resonance (NMR) signal in a weak magnetic field from a small volume of a condensed medium (less than 0.2 mL) using a modulation technique. ...The relationships between the parameters of modulation field
H
m
and
f
m
, generation field
H
1
of the autodyne detector, and the degree of inhomogeneity of magnetic field
H
0
for recording the NMR signal from the investigated medium with a signal-to-noise ratio of at least 1.3 are determined. To expand the functionality of the small-sized NMR spectrometer, a new design of the magnetic system was developed and implemented using step inserts made of soft magnetic material.
A model is proposed for describing the line shape of absorption and dispersion signals from which a recorded signal of nuclear magnetic resonance (NMR) is formed in a weak field. The expediency of ...using spectral analysis to determine the contributions of absorption and dispersion signals to the recorded NMR signal has been substantiated using a modulation technique. A new method is proposed for determining these contributions. The research results are presented.
In an article the influence of active and passive interferences on the operation of X-band radar are considered. A new way to compensate for this interference is proposed. To implement this method, a ...new interference compensation unit based on horn antennas is developed. The experimental investigation results of unit work, as a separate device, and as part of the radar station are presented.
The design of a magnetic trap for low mass-dimensional microwave frequency standards is presented. The dependencies of the number of photons registered by PMT on magnetic field values are ...established. The new algorithm for optical processing has been developed. The comparison of experimental Allan deviation for different designs of microwave frequency standards on 199Hg+ ions has been performed.
Self-assembly of short de novo designed peptides gives rise to catalytic amyloids capable of facilitating multiple chemical transformations. We show that catalytic amyloids can efficiently hydrolyze ...paraoxon, which is a widely used, highly toxic organophosphate pesticide. Moreover, these robust and inexpensive metal-containing materials can be easily deposited on various surfaces, producing catalytic flow devices. Finally, functional promiscuity of catalytic amyloids promotes tandem hydrolysis/oxidation reactions. High efficiency discovered in a very small library of peptides suggests an enormous potential for further improvement of catalytic properties, both in terms of catalytic efficiency and substrate scope.
•The surface of comet 67P/CG has been imaged by the VIRTIS instrument aboard ROSETTA.•Refractory polyaromatic organics mixed with opaque minerals account for the low albedo.•Semi-volatiles organics ...(solid at 220K) induce a broad band centered at 3.2µm.•Laboratory photolytic/thermal residues formed from interstellar ice analogs are fair analogs.•No hydrated minerals are detected, suggesting no link with carbonaceous chondrites.
The VIRTIS (Visible, Infrared and Thermal Imaging Spectrometer) instrument aboard the Rosetta spacecraft has performed extensive spectral mapping of the surface of comet 67P/Churyumov-Gerasimenko in the range 0.3–5µm. The reflectance spectra collected across the surface display a low reflectance factor over the whole spectral range, two spectral slopes in the visible and near-infrared ranges and a broad absorption band centered at 3.2µm. The first two of these characteristics are typical of dark small bodies of the Solar System and are difficult to interpret in terms of composition. Moreover, solar wind irradiation may modify the structure and composition of surface materials and there is no unequivocal interpretation of these spectra devoid of vibrational bands. To circumvent these problems, we consider the composition of cometary grains analyzed in the laboratory to constrain the nature of the cometary materials and consider results on surface rejuvenation and solar wind processing provided by the OSIRIS and ROSINA instruments, respectively. Our results lead to five main conclusions: (i) The low albedo of comet 67P/CG is accounted for by a dark refractory polyaromatic carbonaceous component mixed with opaque minerals. VIRTIS data do not provide direct insights into the nature of these opaque minerals. However, according to the composition of cometary grains analyzed in the laboratory, we infer that they consist of Fe-Ni alloys and FeS sulfides. (ii) A semi-volatile component, consisting of a complex mix of low weight molecular species not volatilized at T∼220K, is likely a major carrier of the 3.2µm band. Water ice contributes significantly to this feature in the neck region but not in other regions of the comet. COOH in carboxylic acids is the only chemical group that encompasses the broad width of this feature. It appears as a highly plausible candidate along with the NH4+ ion. (iii) Photolytic/thermal residues, produced in the laboratory from interstellar ice analogs, are potentially good spectral analogs. (iv) No hydrated minerals were identified and our data support the lack of genetic links with the CI, CR and CM primitive chondrites. This concerns in particular the Orgueil chondrite, previously suspected to have been of cometary origin. (v) The comparison between fresh and aged terrains revealed no effect of solar wind irradiation on the 3.2µm band. This is consistent with the presence of efficient resurfacing processes such as dust transport from the interior to the surface, as revealed by the OSIRIS camera.
The mechanistic understanding of nascent RNAs in transcriptional control remains limited. Here, by a high sensitivity method methylation-inscribed nascent transcripts sequencing (MINT-seq), we ...characterized the landscapes of N6-methyladenosine (m6A) on nascent RNAs. We uncover heavy but selective m6A deposition on nascent RNAs produced by transcription regulatory elements, including promoter upstream antisense RNAs and enhancer RNAs (eRNAs), which positively correlates with their length, inclusion of m6A motif, and RNA abundances. m6A-eRNAs mark highly active enhancers, where they recruit nuclear m6A reader YTHDC1 to phase separate into liquid-like condensates, in a manner dependent on its C terminus intrinsically disordered region and arginine residues. The m6A-eRNA/YTHDC1 condensate co-mixes with and facilitates the formation of BRD4 coactivator condensate. Consequently, YTHDC1 depletion diminished BRD4 condensate and its recruitment to enhancers, resulting in inhibited enhancer and gene activation. We propose that chemical modifications of eRNAs together with reader proteins play broad roles in enhancer activation and gene transcriptional control.
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•MINT-seq is of high sensitivity to characterize m6A methylome on nascent RNAs•There is a pervasive but also selective m6A deposition to long and stable eRNAs•m6A-eRNAs recruit YTHDC1 to enhancers to stimulate enhancer and gene activation•m6A-eRNA/YTHDC1 phase separate to facilitate transcriptional condensate formation
Lee, Wang, Xiong, et al. characterized nascent RNA m6A methylome in human cells, finding a pervasive existence of m6A-marked eRNAs. These m6A-modified eRNAs recruit the nuclear m6A reader YTHDC1 to partition into liquid-like condensates, which facilitate formation of transcriptional activator condensates and therefore gene activation.
The results obtained by determining the flux density of neutrons produced with energies of up to 20 MeV upon the irradiation of a beryllium target 1.3 mm thick with a beam of 21.3-MeV protons are ...presented. The proton flux density was determined by means of standard instruments and was controlled with the aid of the monitoring reactions
Cu
Zn and
Cu
Zn, while the neutron flux density was determined using the reactions
Al
Mg and
Al
Na. The proton and neutron spectra at the center of experimental samples were calculated using the PHITS code.
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