Abstract
Stellar metallicity is a critical factor to characterize the stellar coronae because it directly affects the radiative energy loss from the atmosphere. By extending theoretical relations for ...solar coronal loops introduced by Rosner et al., we analytically derive scaling relations for stellar coronal loops with various metallicities. In order to validate the derived relations, we also perform magnetohydrodynamic simulations for the heating of coronal loops with different metallicities by changing radiative-loss functions according to the adopted elemental abundances. The simulation results nicely explain the generalized analytical scaling relations and show a strong dependence of the thermodynamical and radiative properties of the loops on metallicity. Higher density and temperature are obtained in lower-metallicity coronae because of the inefficient radiative cooling, provided that the surface condition is unchanged. Thus, it is estimated that the X-ray radiation from metal-poor coronae is higher because of their denser coronal gas. The generalized scaling laws can also be used as a tool to study the condition of high-energy radiation around magnetically active stars and their impact on planetary environments.
The cerebral cortex underwent rapid expansion and increased complexity during recent hominid evolution. Gene duplications constitute a major evolutionary force, but their impact on human brain ...development remains unclear. Using tailored RNA sequencing (RNA-seq), we profiled the spatial and temporal expression of hominid-specific duplicated (HS) genes in the human fetal cortex and identified a repertoire of 35 HS genes displaying robust and dynamic patterns during cortical neurogenesis. Among them NOTCH2NL, human-specific paralogs of the NOTCH2 receptor, stood out for their ability to promote cortical progenitor maintenance. NOTCH2NL promote the clonal expansion of human cortical progenitors, ultimately leading to higher neuronal output. At the molecular level, NOTCH2NL function by activating the Notch pathway through inhibition of cis Delta/Notch interactions. Our study uncovers a large repertoire of recently evolved genes active during human corticogenesis and reveals how human-specific NOTCH paralogs may have contributed to the expansion of the human cortex.
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•Identification of >35 HS protein-coding genes expressed during human corticogenesis•NOTCH2NL human-specific paralogs of NOTCH2 expressed in human cortical progenitors•NOTCH2NL genes expand human cortical progenitors and their neuronal output•NOTCH2NL promotes Notch signaling through cis-inhibition of Delta/Notch interactions
Human-specific NOTCH2NL expands cortical progenitors and neuronal output and thus may have contributed to the expansion of the human cortex.
Using numerical simulations we investigate the onset and suppression of parametric decay instability (PDI) in the solar wind, focusing on the suppression effect by the wind acceleration and ...expansion. Wave propagation and dissipation from the coronal base to 1 au is solved numerically in a self-consistent manner; we take into account the feedback of wave energy and pressure in the background. Monochromatic waves with various injection frequencies, f0, are injected to discuss the suppression of PDI, while broadband waves are applied to compare the numerical results with observation. We find that high-frequency ( ) Alfvén waves are subject to PDI. Meanwhile, the maximum growth rate of the PDI of low-frequency ( ) Alfvén waves becomes negative due to acceleration and expansion effects. Medium-frequency ( ) Alfvén waves have a positive growth rate but do not show the signature of PDI up to 1 au because the growth rate is too small. The medium-frequency waves experience neither PDI nor reflection so they propagate through the solar wind most efficiently. The solar wind is shown to possess a frequency-filtering mechanism with respect to Alfvén waves. The simulations with broadband waves indicate that the observed trend of the density fluctuation is well explained by the evolution of PDI while the observed cross-helicity evolution is in agreement with low-frequency wave propagation.
ABSTRACT
We systematically investigated the heating of coronal loops on metal-free stars with various stellar masses and magnetic fields by magnetohydrodynamic simulations. It is found that the ...coronal property is dependent on the coronal magnetic field strength Bc because it affects the difference of the non-linearity of the Alfvénic waves. Weaker Bc leads to cooler and less dense coronae because most of the input waves dissipate in the lower atmosphere on account of the larger non-linearity. Accordingly EUV and X-ray luminosities also correlate with Bc, while they are emitted in a wide range of the field strength. Finally, we extend our results to evaluating the contribution from low-mass Population III coronae to the cosmic reionization. Within the limited range of our parameters on magnetic fields and loop lengths, the EUV and X-ray radiations give a weak impact on the ionization and heating of the gas at high redshifts. However, there still remains a possibility of the contribution to the reionization from energetic flares involving long magnetic loops.
•Effect of Co addition on ultra-rapidly annealed HiB-Nanoperm investigated.•Nanocrystalline (Fe0.8Co0.2)87B13 displays a Js of 2.02 T and a Hc of 9.3 A/m.•Addition of 1 at.% Cu improves magnetic ...softness for Co-containing HiB-Nanoperm.•(Fe0.8Co0.2)86B13Cu1 displays a Js of 2.00 T and a Hc of 7.0 A/m.•Ultra-rapid annealing required for magnetic softness in Co-containing HiB-Nanoperm.
The effect of Co on the magnetic properties of ultra-rapidly annealed (heating rate > 104 K/s, annealing time < 1 s) nanocrystalline (Fe1−xCox)87B13 with x = 0–0.5 has been investigated. A saturation magnetic polarization of 2.02 T is observed for x = 0.2 while maintaining a coercivity of 9.3 A/m. This represents a 0.1 T increase over existing Co-free HiB-Nanoperm alloys with a B content of 13 at.% and is directly comparable to conventional crystalline Fe-3 wt%Si. Ultra-rapid annealing is shown to be a requirement for producing magnetically soft materials in this alloy system. The effect of Cu on ultra-rapidly annealed nanocrystalline (Fe0.8Co0.2)87−yB13Cuy where y = 0–1.5 is also investigated. It is found that Cu is effective at improving the magnetic softness of Co-containing HiB-Nanoperm, with y = 1 displaying a Hc of 7 A/m and a saturation magnetic polarization of 2.0 T.
Essentials
We generated recombinant rhodocytin that could aggregate platelets via CLEC‐2.
Recombinant wild‐type rhodocytin formed heterooctamer with four α‐ and β‐subunits.
Asp 4 in α‐subunit of ...rhodocytin was required for binding to CLEC‐2.
Inhibitory mutant of rhodocytin blocked podoplanin‐dependent hematogenous metastasis.
Summary
Background
Rhodocytin, a disulfide‐linked heterodimeric C‐type lectin from Calloselasma rhodostoma consisting of α‐subunits and β‐subunits, induces platelet aggregation through C‐type lectin‐like receptor 2 (CLEC‐2). CLEC‐2 is a physiological binding partner of podoplanin (PDPN), which is expressed on some tumor cell types, and is involved in tumor cell‐induced platelet aggregation and tumor metastasis. Thus, modified rhodocytin may be a possible source of anti‐CLEC‐2 drugs for both antiplatelet and antimetastasis therapy. However, its molecular function has not been well characterized, because of the lack of recombinant rhodocytin that induces platelet aggregation.
Objective
To produce recombinant rhodocytin, in order to verify its function with mutagenesis, and to develop an anti‐CLEC‐2 drug based on the findings.
Methods
We used Chinese hamster ovary cells to express recombinant rhodocytin (wild‐type WT and mutant), which was analyzed for induction/inhibition of platelet aggregation with light transmission aggregometry, the formation of multimers with blue native PAGE, and binding to CLEC‐2 with flow cytometry. Finally, we investigated whether mutant rhodocytin could suppress PDPN‐induced metastasis in an experimental lung metastasis mouse model.
Results
Functional WT rhodocytin (αWTβWT) was obtained by coexpression of both subunits. Asp4 in α‐subunits of rhodocytin was required for CLEC‐2 binding. αWTβWT formed a heterooctamer similarly to native rhodocytin. Moreover, an inhibitory mutant of rhodocytin (αWTβK53A/R56A), forming a heterotetramer, bound to CLEC‐2 without inducing platelet aggregation, and blocked CLEC‐2–PDPN interaction‐dependent platelet aggregation and experimental lung metastasis.
Conclusion
These findings provide molecular characterization information on rhodocytin, and suggest that mutant rhodocytin could be used as a therapeutic agent to target CLEC‐2.
•Human has obtained an exceptionally expanded cerebral cortex during evolution.•There are a few notable structural transitions in evolution until human cerebral cortex had appeared.•Developmental ...programs of the cerebral cortex have been changed in evolution.•Three major classes of genetic changes relevant to the evolutionary alterations of human cortical development have been studied.
One of the most important questions in human evolutionary biology is how our ancestor has acquired an expanded volume of the cerebral cortex, which may have significantly impacted on improving our cognitive abilities. Recent comparative approaches have identified developmental features unique to the human or hominid cerebral cortex, not shared with other animals including conventional experimental models. In addition, genomic, transcriptomic, and epigenomic signatures associated with human- or hominid-specific processes of the cortical development are becoming identified by virtue of technical progress in the deep nucleotide sequencing. This review discusses ontogenic and phylogenetic processes of the human cerebral cortex, followed by the introduction of recent comprehensive approaches identifying molecular mechanisms potentially driving the evolutionary changes in the cortical development.
Abstract
Increased boldness is one of the most prevalent behavioral modifications seen in urban animals and is thought to be a coping response to anthropogenic environmental alterations. Most ...previous studies have shown enhanced boldness manifested as changes in responses to humans approaching, such as reductions in flight initiation distance (FID). However, this includes two confounding factors related to “boldness,” that is, reduction of vigilance and habituation to humans. Confounding these totally different processes could lead to our misunderstanding of urban adaptation and how to properly manage urban wildlife. Here, we propose a simple framework to separate the two processes using two flight distance measures toward different approaching threats. We considered that the distance at which targeted individuals noticed an approaching object (i.e., alert distance, AD) was related to vigilance, whereas FID represented risk assessment, which is related to habituation. We applied a predictive framework using AD and FID to Eurasian red squirrels’ responses to multiple threats of different risk levels (i.e., humans, model predators, and novel objects). AD was shorter in urban individuals compared with rural ones but not different among the approaching objects. FID was shorter in urban individuals and also varied among the objects with the shortest FID toward humans, whereas rural individuals showed similar FID to the different objects. These results suggest that, although urban individuals showed reduced vigilance, they could still assess different risk levels. Our framework can easily be applied to many animals and could significantly improve our understanding of wild animals’ adaptations to urban environments.
Animals often become bolder when colonizing urban environments, facilitating the exploitation of human-mediated resources. We developed a novel framework to separate two mechanisms—a reduction in vigilance (due to loss of natural predators) and habituation to humans—affecting increased boldness. We applied this method to Eurasian red squirrels and found that, although urban squirrels reduced vigilance, they were still able to distinguish between different risk levels, such as humans, predators, and novel objects.
Abstract We investigate the role of magnetic field on the gas dynamics in a galactic bulge region by three-dimensional simulations with radiative cooling and heating. While a high-temperature corona ...with T > 10 6 K is formed in the halo regions, the temperature near the midplane is ≲10 4 K following the thermal equilibrium curve determined by the radiative cooling and heating. Although the thermal energy of the interstellar gas is lost by radiative cooling, the saturation level of the magnetic field strength does not significantly depend on the radiative cooling and heating. The magnetic field strength is amplified to 10 μ G on average and reaches several hundred microgauss locally. We find the formation of magnetically dominated regions at midlatitudes in the case with the radiative cooling and heating, which is not seen in the case without radiative effect. The vertical thickness of the midlatitude regions is 50–150 pc at the radial location of 0.4–0.8 kpc from the Galactic center, which is comparable to the observed vertical distribution of neutral atomic gas. When we take the average of different components of energy density integrated over the galactic bulge region, the magnetic energy is comparable to the thermal energy. We conclude that the magnetic field plays a substantial role in controlling the dynamical and thermal properties of the galactic bulge region.
Essentials
The role of C‐type lectin‐like receptor‐2 (CLEC‐2) in cancer progression is unclear.
CLEC‐2‐depleted mouse model is generated by using a rat anti‐mouse CLEC‐2 monoclonal antibody.
CLEC‐2 ...depletion inhibits hematogenous tumor metastasis of podoplanin‐expressing B16F10 cells.
CLEC‐2 depletion prolongs cancer survival by suppressing thrombosis and inflammation.
Summary
Background
C‐type lectin‐like receptor 2 (CLEC‐2) is a platelet activation receptor of sialoglycoprotein podoplanin, which is expressed on the surface of certain types of tumor cells. CLEC‐2–podoplanin interactions facilitate hematogenous tumor metastasis. However, direct evidence of the role of CLEC‐2 in hematogenous metastasis and cancer progression is lacking.
Objective and methods
We generated immunological CLEC‐2‐depleted mice by using anti‐mouse CLEC‐2 monoclonal antibody 2A2B10 and investigated whether CLEC‐2 promoted hematogenous tumor metastasis and tumor growth and exacerbated the prognosis of mice bearing podoplanin‐expressing B16F10 melanoma cells.
Results
Our results showed that hematogenous metastasis was significantly inhibited in CLEC‐2‐depleted mice. B16F10 cells co‐cultured with wild‐type platelets, but not with CLEC‐2‐deficient platelets, showed increased proliferation. However, B16F10 cell proliferation was not inhibited in CLEC‐2‐depleted mice. Histological analysis showed that thrombus formation in tumor vessels was significantly inhibited and functional vessel density was significantly increased in CLEC‐2‐depleted mice. These data suggest that CLEC‐2 deficiency may inhibit thrombus formation in tumor vessels and increase the density of functional vessels, thus improving oxygen and nutrient supply to tumors, indirectly promoting tumor proliferation. Furthermore, the overall survival of CLEC‐2‐depleted mice was significantly prolonged, which may be due to the suppression of thrombus formation in the lungs and subsequent inhibition of systemic inflammation and cachexia.
Conclusions
These data provide a rationale for the targeted inhibition of CLEC‐2 as a new strategy for preventing hematogenous tumor metastasis and for inhibiting cancer‐related thromboembolism.
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