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Exploring the Phytochemical Landscape of the Early-Diverging Flowering Plant Amborella trichopoda Baill.
Although the evolutionary significance of the early-diverging flowering plant Amborella (Amborella trichopoda Baill.) is widely recognized, its metabolic landscape, particularly specialized metabolites, is currently underexplored. In this work, we analyzed the metabolomes of Amborella tissues using liquid chromatography high-resolution electrospray ionization mass spectrometry (LC-HR-ESI-MS). By matching the mass spectra of Amborella metabolites with those of authentic phytochemical standards in the publicly accessible libraries, 63, 39, and 21 compounds were tentatively identified in leaves, stems, and roots, respectively. Free amino acids, organic acids, simple sugars, cofactors, as well as abundant glycosylated and/or methylated phenolic specialized metabolites were observed in Amborella leaves. Diverse metabolites were also detected in stems and roots, including those that were not identified in leaves. To understand the biosynthesis of specialized metabolites with glycosyl and methyl modifications, families of small molecule UDP-dependent glycosyltransferases (UGTs) and O-methyltransferases (OMTs) were identified in the Amborella genome and the InterPro database based on conserved functional domains. Of the 17 phylogenetic groups of plant UGTs (A-Q) defined to date, Amborella UGTs are absent from groups B, N, and P, but they are highly abundant in group L. Among the 25 Amborella OMTs, 7 cluster with caffeoyl-coenzyme A (CCoA) OMTs involved in lignin and phenolic metabolism, whereas 18 form a clade with plant OMTs that methylate hydroxycinnamic acids, flavonoids, or alkaloids. Overall, this first report of metabolomes and candidate metabolic genes in Amborella provides a starting point to a better understanding of specialized metabolites and biosynthetic enzymes in this basal lineage of flowering plants
Multi-kernel Correntropy-based Orientation Estimation of IMUs: Gradient Descent Methods
This paper presents two computationally efficient algorithms for the
orientation estimation of inertial measurement units (IMUs): the
correntropy-based gradient descent (CGD) and the correntropy-based decoupled
orientation estimation (CDOE). Traditional methods, such as gradient descent
(GD) and decoupled orientation estimation (DOE), rely on the mean squared error
(MSE) criterion, making them vulnerable to external acceleration and magnetic
interference. To address this issue, we demonstrate that the multi-kernel
correntropy loss (MKCL) is an optimal objective function for maximum likelihood
estimation (MLE) when the noise follows a type of heavy-tailed distribution. In
certain situations, the estimation error of the MKCL is bounded even in the
presence of arbitrarily large outliers. By replacing the standard MSE cost
function with MKCL, we develop the CGD and CDOE algorithms. We evaluate the
effectiveness of our proposed methods by comparing them with existing
algorithms in various situations. Experimental results indicate that our
proposed methods (CGD and CDOE) outperform their conventional counterparts (GD
and DOE), especially when faced with external acceleration and magnetic
disturbances. Furthermore, the new algorithms demonstrate significantly lower
computational complexity than Kalman filter-based approaches, making them
suitable for applications with low-cost microprocessors
Multi-kernel Correntropy Regression: Robustness, Optimality, and Application on Magnetometer Calibration
This paper investigates the robustness and optimality of the multi-kernel
correntropy (MKC) on linear regression. We first derive an upper error bound
for a scalar regression problem in the presence of arbitrarily large outliers
and reveal that the kernel bandwidth should be neither too small nor too big in
the sense of the lowest upper error bound. Meanwhile, we find that the proposed
MKC is related to a specific heavy-tail distribution, and the level of the
heavy tail is controlled by the kernel bandwidth solely. Interestingly, this
distribution becomes the Gaussian distribution when the bandwidth is set to be
infinite, which allows one to tackle both Gaussian and non-Gaussian problems.
We propose an expectation-maximization (EM) algorithm to estimate the parameter
vectors and explore the kernel bandwidths alternatively. The results show that
our algorithm is equivalent to the traditional linear regression under Gaussian
noise and outperforms the conventional method under heavy-tailed noise. Both
numerical simulations and experiments on a magnetometer calibration application
verify the effectiveness of the proposed method
-mode of neutron stars in pseudo-Newtonian gravity
The equation of state (EOS) of nuclear dense matter plays a crucial role in
many astrophysical phenomena associated with neutron stars (NSs). Fluid
oscillations are one of the most fundamental properties therein. NSs support a
family of gravity -modes, which are related to buoyancy. We study the
gravity -modes caused by composition gradient and density discontinuity in
the framework of pseudo-Newtonian gravity. The mode frequencies are calculated
in detail and compared with Newtonian and general-relativistic (GR) solutions.
We find that the -mode frequencies in one of the pseudo-Newtonian treatments
can approximate remarkably well the GR solutions, with relative errors in the
order of . Our findings suggest that, with much less computational cost,
pseudo-Newtonian gravity can be utilized to accurately analyze oscillation of
NSs constructed from an EOS with a first-order phase transition between nuclear
and quark matter, as well as to provide an excellent approximation of GR
effects in core-collapse supernova (CCSN) simulations.Comment: 14 pages, 13 figures, 6 tables; accepted by PR
The promotion and inhibition of chromium and kinetic analysis on the growth of Platymonas Helgolandica
In this work, Platymonas helgolandica was used as an experimental material to study the effect of chromium on it. Under the experimental ecological condition, the concentrations of Cr (VI) were set as 0, 0.05, 0.1, 1, and 10 mg/L. Every concentration designed with three parallel groups. The ecotoxicology method was used to investigate the impact of Cr (VI) on P. helgolandica, and (EC50) was calculated by the method of linear interpolation. The results showed the growth of P. helgolandica had a more obvious βHormesisβ when chromium was 0.05 mg/L. However, with Cr (VI) increased, the inhibition on P. helgolandica was increasing, and the cell density of P. helgolandica decreased. The EC50 achieved at 24 h, 48 h, and 72 h revealed that the relative growth rate had a downward trend over time. The remodified Logistic model, the modified Gompertz model, and the Logistic model were suitable to describe cell density in an operating cycle and were beneficial to explore the growth of P. helgolandica
Phosphorylation Modification of Wheat Lectin VER2 Is Associated with Vernalization-Induced O-GlcNAc Signaling and Intracellular Motility
BACKGROUND: O-linked beta-N-acetylglucosamine (O-GlcNAc) modification of proteins mediates stress response and cellular motility in animal cells. The plant lectin concanavalin A can increase nuclear O-GlcNAc levels and decrease cytoplasmic O-GlcNAc levels in T lymphocytes. However, the functions of O-GlcNAc signaling in plants, as well as the relation between plant lectins and O-GlcNAc in response to environmental stimuli are largely undefined. METHODOLOGY/PRINCIPAL FINDINGS: We describe a jacalin-like lectin VER2 in wheat that shows N-acetylglucosamine and galactose specificity. Immunocytochemical localization showed VER2 expression induced predominantly at potential nuclear structures in shoot tips and young leaves and weakly in cytoplasm in response to vernalization. In contrast, under devernalization (continuous stimulation with a higher temperature after vernalization), VER2 signals appeared predominantly in cytoplasm. 2-D electrophoresis, together with western blot analysis, showed phosphorylation modification of VER2 under vernalization. Immunoblot assay with O-GlcNAc-specific antibody revealed that vernalization increased O-GlcNAc modification of proteins at the global level. An O-GlcNAc-modified protein co-immunoprecipitated with VER2 in vernalized wheat plants but not in devernalized materials. The dynamic of VER2 was observed in transgenic Arabidopsis overexpressing the VER2-GFP fusion protein. Overexpressed VER2 accelerated nuclear migration. Immunogold labeling and indirect immunofluoresence colocalization assay indicated that VER2-GFP was targeted to the secretory pathway. CONCLUSIONS/SIGNIFICANCE: O-GlcNAc signaling is involved in the vernalization response in wheat, and phosphorylation is necessary for the lectin VER2 involving O-GlcNAc signaling during vernalization. Our findings open the way to studies of O-GlcNAc protein modification in response to environmental signals in plants
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