ABSTRACT
Astrochemistry has been widely developed as a power tool to probe the physical properties of the interstellar medium (ISM) in various conditions of the Milky Way (MW) Galaxy, and in near and ...distant galaxies. Most current studies conventionally apply linear scaling to all elemental abundances based on the gas-phase metallicity. However, these elements, including carbon and oxygen, are enriched differentially by stellar nucleosynthesis and the overall galactic chemical evolution, evident from α-enhancement in multiple galactic observations such as starbursts, high-redshift star-forming galaxies, and low-metallicity dwarfs. We perform astrochemical modelling to simulate the impact of an α-enhanced ISM gas cloud on the abundances of the three phases of carbon (C+, C, CO) dubbed as ‘the carbon cycle’. The ISM environmental parameters considered include two cosmic-ray ionization rates (ζCR = 10−17 and $10^{-15}\, {\rm s}^{-1}$), two isotropic FUV radiation field strengths (χ/χ0 = 1 and 102), and (sub-)linear dust-to-gas relations against metallicity, mimicking the ISM conditions of different galaxy types. In galaxies with C/O < 0, CO, C, and C+, all decrease in both abundances and emission, though with differential biases. The low-J CO emission is found to be the most stable tracer for the molecular gas, while C and C+ trace H2 gas only under limited conditions, in line with recent discoveries of C i-dark galaxies. We call for caution when using C ii $158\, \mu$m and C i(1–0) as alternative H2-gas tracers for both diffuse and dense gas with non-zero C/O ratios.
The extraction adsorbent was fabricated by immobilizing the highly specific recognition and binding of aptamer onto the surface of Fe3O4 magnetic nanoparticles, which not only acted as recognition ...elements to recognize and capture the target molecule berberine from the extract of Cortex phellodendri, but also could favor the rapid separation and purification of the bound berberine by using an external magnet. The developed solid‐phase extraction method in this work was useful for the selective extraction and determination of berberine in Cortex phellodendri extracts. Various conditions such as the amount of aptamer‐functionalized Fe3O4 magnetic nanoparticles, extraction time, temperature, pH value, Mg2+ concentration, elution time and solvent were optimized for the solid‐phase extraction of berberine. Under optimal conditions, the purity of berberine extracted from Cortex phellodendri was as high as 98.7% compared with that of 4.85% in the extract, indicating that aptamer‐functionalized Fe3O4 magnetic nanoparticles‐based solid‐phase extraction method was very effective for berberine enrichment and separation from a complex herb extract. The applicability and reliability of the developed solid‐phase extraction method were demonstrated by separating berberine from nine different concentrations of one Cortex phellodendri extract. The relative recoveries of the spiked solutions of all the samples were between 95.4 and 111.3%, with relative standard deviations ranging between 0.57 and 1.85%.
Although vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are under development, the antigen epitopes on the virus and their immunogenicity are poorly understood. Here, ...we simulate the 3D structures and predict the B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches and validate epitope immunogenicity by immunizing mice. Almost all 33 predicted epitopes effectively induce antibody production, six of these are immunodominant epitopes in individuals, and 23 are conserved within SARS-CoV-2, SARS-CoV, and bat coronavirus RaTG13. We find that the immunodominant epitopes of individuals with domestic (China) SARS-CoV-2 are different from those of individuals with imported (Europe) SARS-CoV-2, which may be caused by mutations on the S (G614D) and N proteins. Importantly, we find several epitopes on the S protein that elicit neutralizing antibodies against D614 and G614 SARS-CoV-2, which can contribute to vaccine design against coronaviruses.
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•B cell epitopes of SARS-CoV-2 are obtained using structure-based approaches•The predicted epitopes effectively induce robust antibody responses•D614 and G614 SARS-CoV-2 display different immunodominant epitopes•Epitopes on S protein elicit D614 and/or G614 SARS-CoV-2-neutralizing antibodies
Lu et al. predict and validate B cell epitopes on the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins of SARS-CoV-2 using structure-based approaches. The immunodominant epitopes vary between D614 and G614 SARS-CoV-2. The epitopes on the S protein elicit neutralizing antibodies against D614 and G614 SARS-CoV-2.
Abstract
We present
and
maps of six nearby star-forming galaxies, NGC 253, NGC 1068, IC 342, M82, M83, and NGC 6946, obtained with the James Clerk Maxwell Telescope as part of the MALATANG survey. ...All galaxies were mapped in the central 2′ × 2′ region at 14″ (FWHM) resolution (corresponding to linear scales of ∼0.2–1.0 kpc). The
L
IR
–
L
′
dense
relation, where the dense gas is traced by the
and the
emission, measured in our sample of spatially resolved galaxies is found to follow the linear correlation established globally in galaxies within the scatter. We find that the luminosity ratio,
L
IR
/
L
′
dense
, shows systematic variations with
L
IR
within individual spatially resolved galaxies, whereas the galaxy-integrated ratios vary little. A rising trend is also found between
L
IR
/
L
′
dense
ratio and the warm-dust temperature gauged by the 70
μ
m/100
μ
m flux ratio. We find that the luminosity ratios of IR/HCN (4–3) and IR/HCO
+
(4–3), which can be taken as a proxy for the star formation efficiency (SFE) in the dense molecular gas (SFE
dense
), appear to be nearly independent of the dense gas fraction (
f
dense
) for our sample of galaxies. The SFE of the total molecular gas (SFE
mol
) is found to increase substantially with
f
dense
when combining our data with those on local (ultra)luminous infrared galaxies and high-
z
quasars. The mean
line ratio measured for the six targeted galaxies is 0.9 ± 0.6. No significant correlation is found for the
ratio with the star formation rate as traced by
L
IR
, nor with the warm-dust temperature, for the different populations of galaxies.
We present CO J = 2-1 observations toward 32 nearby gas-rich star-forming galaxies selected from the ALFALFA and Wide-field Infrared Survey Explorer (WISE) catalogs, using the Sub-millimeter ...Telescope (SMT). The scaling relations between molecular gas, atomic gas, and galactic properties (stellar mass, NUV - r, and WISE color W3 - W2) are examined and discussed. The correlation may reflect that the cold gas and dust are well mixed on a global galactic scale. Using the all-sky 12 mu m (W3) data available in WISE, this correlation can be used to estimate CO flux for molecular gas observations and can even predict Hsub 2 mass for star-forming galaxies.
Methylation of cytosine to 5-methylcytosine (5mC) is a prevalent DNA modification found in many organisms. Sequential oxidation of 5mC by ten-eleven translocation (TET) dioxygenases results in a ...cascade of additional epigenetic marks and promotes demethylation of DNA in mammals
. However, the enzymatic activity and function of TET homologues in other eukaryotes remains largely unexplored. Here we show that the green alga Chlamydomonas reinhardtii contains a 5mC-modifying enzyme (CMD1) that is a TET homologue and catalyses the conjugation of a glyceryl moiety to the methyl group of 5mC through a carbon-carbon bond, resulting in two stereoisomeric nucleobase products. The catalytic activity of CMD1 requires Fe(II) and the integrity of its binding motif His-X-Asp, which is conserved in Fe-dependent dioxygenases
. However, unlike previously described TET enzymes, which use 2-oxoglutarate as a co-substrate
, CMD1 uses L-ascorbic acid (vitamin C) as an essential co-substrate. Vitamin C donates the glyceryl moiety to 5mC with concurrent formation of glyoxylic acid and CO
. The vitamin-C-derived DNA modification is present in the genome of wild-type C. reinhardtii but at a substantially lower level in a CMD1 mutant strain. The fitness of CMD1 mutant cells during exposure to high light levels is reduced. LHCSR3, a gene that is critical for the protection of C. reinhardtii from photo-oxidative damage under high light conditions, is hypermethylated and downregulated in CMD1 mutant cells compared to wild-type cells, causing a reduced capacity for photoprotective non-photochemical quenching. Our study thus identifies a eukaryotic DNA base modification that is catalysed by a divergent TET homologue and unexpectedly derived from vitamin C, and describes its role as a potential epigenetic mark that may counteract DNA methylation in the regulation of photosynthesis.
The utilization of black beans as a protein-rich ingredient presents remarkable prospects in the protein food industry. The objective of this study was to assess the impact of germination treatment ...on the physicochemical, structural, and functional characteristics of a black bean protein isolate. The findings indicate that germination resulted in an increase in both the total and soluble protein contents of black beans, while SDS-PAGE demonstrated an increase in the proportion of 11S and 7S globulin subunits. After germination, the particle size of the black bean protein isolate decreased in the solution, while the absolute value of the zeta potential increased. The above results show that the stability of the solution was improved. The contents of β-sheet and β-turn gradually decreased, while the content of α-helix increased, and the fluorescence spectrum of the black bean protein isolate showed a red shift phenomenon, indicating that the structure of the protein isolate and its polypeptide chain were prolonged, and the foaming property, emulsification property and in vitro digestibility were significantly improved after germination. Therefore, germination not only improves functional properties, but also nutritional content.
The Tachinidae are natural enemies of many lepidopteran and coleopteran pests of crops, forests, and fruits. However, host-tachinid parasitoid interactions have been largely unexplored. In this ...study, we investigated the effects of tachinids on host biological traits, using
, a generalist parasitoid, and the silkworm
, its lepidopteran host, as models. We observed that
parasitoidism did not affect silkworm larval body weight gain and cocooning rate, whereas they caused shortened duration of molting from the final instar to the pupal stage, abnormal molting from larval to pupal stages, and a subsequent decrease in host emergence rate. Moreover, a decrease in juvenile hormone (JH) titer and an increase in 20-hydroxyecdysone (20E) titer in the hemolymph of parasitized silkworms occurred. The transcription of JH and 20E responsive genes was downregulated in mature parasitized hosts, but upregulated in parasitized prepupae while Fushi tarazu factor 1 (
), a nuclear receptor essential in larval ecdysis, showed dramatically reduced expression in parasitized hosts at both the mature and prepupal stages. Moreover, the transcriptional levels of
and its downstream target genes encoding cuticle proteins were downregulated in epidermis of parasitized hosts. Meanwhile, the content of trehalose was decreased in the hemolymph, while chitin content in the epidermis was increased in parasitized silkworm prepupae. These data reveal that the host may fine-tune JH and 20E synthesis to shorten developmental duration to combat established
infestation, while
silences
transcription to inhibit host pupation. This discovery highlights the novel target mechanism of tachinid parasitoids and provides new clues to host/tachinid parasitoid relationships.
ABSTRACT
To study the high-transition dense-gas tracers and their relationships to the star formation of the inner ∼2 kpc circumnuclear region of NGC 253, we present HCN J = 4−3 and HCO+ J = 4−3 maps ...obtained with the James Clerk Maxwell Telescope. Using the spatially resolved data, we compute the concentration indices r90/r50 for the different tracers. HCN and HCO+ 4–3 emission features tend to be centrally concentrated, which is in contrast to the shallower distribution of CO 1–0 and the stellar component. The dense-gas fraction (fdense, traced by the velocity-integrated-intensity ratios of HCN/CO and HCO+/CO) and the ratio R31 (CO 3–2/1–0) decline towards larger galactocentric distances, but increase with higher star formation rate surface density. The radial variation and the large scatter of fdense and R31 imply distinct physical conditions in different regions of the galactic disc. The relationships of fdense versus Σstellar, and SFEdense versus Σstellar are explored. SFEdense increases with higher Σstellar in this galaxy, which is inconsistent with previous work that used HCN 1–0 data. This implies that existing stellar components might have different effects on the high-J HCN and HCO+ than their low-J emission. We also find that SFEdense seems to be decreasing with higher fdense which is consistent with previous works, and it suggests that the ability of the dense gas to form stars diminishes when the average density of the gas increases. This is expected in a scenario where only the regions with high-density contrast collapse and form stars.
Chinese Tajiks are an Indo‐Iranian‐speaking population in Xinjiang, northwest China. Although the complex demographic history has been characterized, the ancestral sources and genetic admixture of ...Indo‐Iranian‐speaking groups in this region remain poorly understood. We here provide the genome‐wide genotyping data for over 700 000 single‐nucleotide polymorphisms (SNPs) and mtDNA multiplex sequencing data in 64 Chinese male Tajik individuals from two dialect groups, Wakhi and Selekur. We applied principal component analysis (PCA), ADMIXTURE, f‐statistics, treemix, qpWave/qpAdm, Admixture‐induced Linkage Disequilibrium for Evolutionary Relationships (ALDER), and Fst analyses to infer a fine‐scale population genetic structure and admixture history. Our results reveal that Chinese Tajiks showed the closest affinity and similar genetic admixture pattern with ancient Xinjiang populations, especially Xinjiang samples in the historical era. Chinese Tajiks also have gene flow from European and Neolithic Iran farmers‐related populations. We observed a genetic substructure in the two Tajik dialect groups. The Selekur‐speaking group who lived in the county had more gene flow from East Asians than Wakhi‐speaking people who inhabited the village. These results document the population movements contributed to the influx of diverse ancestries in the Xinjiang region.
Chinese Tajiks are an Indo‐Iranian‐speaking population in Xinjiang, northwest China. Although the complex demographic history has been characterized, the ancestral sources and genetic admixture of Indo‐Iranian‐speaking groups in this region remain poorly understood. We here provide the first batch of genome‐wide genotyping data for over 700 000 single‐nucleotide polymorphisms (SNPs) and mtDNA multiplex sequencing data in 64 male Chinese Tajik samples involved with two neighboring dialect groups, Wakhi and Selekur. We applied principal component analysis (PCA), ADMIXTURE, f‐statistics, treemix, qpWave/qpAdm analysis, Admixture‐induced Linkage Disequilibrium for Evolutionary Relationships (ALDER), and Fst to infer a fine‐scale population genetic structure and admixture history. Our results reveal that Chinese Tajiks showed the closest affinity and similar genetic admixture pattern with ancient Xinjiang populations, especially Xinjiang samples in the historical era. Chinese Tajiks also have gene flow from European populations and Neolithic Iran farmers. The Wakhi‐ and Selekur‐speaking populations had similar admixture patterns; the only difference is that the Selekur‐speaking group who lived in the county had more gene flow from East Asians than Wakhi‐speaking people who inhabited the village. These results document the population movements contributing to an extensive influx of diverse ancestries in the Xinjiang region.
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