Summary
Plant somatic cells can be reprogrammed by in vitro tissue culture methods, and massive genome‐wide chromatin remodeling occurs, particularly during callus formation. Since callus tissue ...resembles root primordium, conversion of tissue identity is essentially required when leaf explants are used. Consistent with the fact that the differentiation state is defined by chromatin structure, which permits limited gene profiles, epigenetic changes underlie cellular reprogramming for changes to tissue identity. Although a histone methylation process suppressing leaf identity during leaf‐to‐callus transition has been demonstrated, the epigenetic factor involved in activation of root identity remains elusive. Here, we report that JUMONJI C DOMAIN‐CONTAINING PROTEIN 30 (JMJ30) stimulates callus formation by promoting expression of a subset of LATERAL ORGAN BOUNDARIES‐DOMAIN (LBD) genes that establish root primordia. The JMJ30 protein binds to promoters of the LBD16 and LBD29 genes along with AUXIN RESPONSE FACTOR 7 (ARF7) and ARF19 and activates LBD expression. Consistently, the JMJ30‐deficient mutant displays reduced callus formation with low LBD transcript levels. The ARF–JMJ30 complex catalyzes the removal of methyl groups from H3K9me3, especially at the LBD16 and LBD29 loci to activate their expression during leaf‐to‐callus transition. Moreover, the ARF–JMJ30 complex further recruits ARABIDOPSIS TRITHORAX‐RELATED 2 (ATXR2), which promotes deposition of H3K36me3 at the LBD16 and LBD29 promoters, and the tripartite complex ensures stable LBD activation during callus formation. These results indicate that the coordinated epigenetic modifications promote callus formation by establishing root primordium identity.
Significance Statement
The ARF–JMJ30 complex activates the LBD genes to accelerate callus formation. JMJ30 binds primarily to LBD16 and LBD29 promoters and removes the repressive H3K9me3 mark from the promoters to ensure efficient cell fate changes.
Summary
Chromatin configuration is critical for establishing tissue identity and changes substantially during tissue identity transitions. The crucial scientific and agricultural technology of in ...vitro tissue culture exploits callus formation from diverse tissue explants and tissue regeneration via de novo organogenesis. We investigated the dynamic changes in H3ac and H3K4me3 histone modifications during leaf‐to‐callus transition in Arabidopsis thaliana.
We analyzed changes in the global distribution of H3ac and H3K4me3 during the leaf‐to‐callus transition, focusing on transcriptionally active regions in calli relative to leaf explants, defined by increased accumulation of both H3ac and H3K4me3.
Peptide signaling was particularly activated during callus formation; the peptide hormones RGF3, RGF8, PIP1 and PIPL3 were upregulated, promoting callus proliferation and conferring competence for de novo shoot organogenesis. The corresponding peptide receptors were also implicated in peptide‐regulated callus proliferation and regeneration capacity. The effect of peptide hormones in plant regeneration is likely at least partly conserved in crop plants.
Our results indicate that chromatin‐dependent regulation of peptide hormone production not only stimulates callus proliferation but also establishes pluripotency, improving the overall efficiency of two‐step regeneration in plant systems.
This letter proposes an efficient probability-based ordered-statistics decoding (PB-OSD) algorithm for short block-length codes. In PB-OSD, we derive two probabilistic measures on the codeword ...estimates and test error patterns, respectively referred to as the success probability and promising probability. Based on these probabilities, a stopping criterion and a discarding criterion are developed to reduce the number of test error patterns and limit the decoding complexity. To further reduce the complexity, we propose a tree-based search strategy to find the most likely test error patterns in reprocessing stage of the OSD algorithm. Simulation results show that PB-OSD significantly reduces the decoding complexity under the same error performance, compared to the original OSD algorithm.
Abstract
Bone resorption can be caused by excessive differentiation and/or activation of bone‐resorbing osteoclasts. While microbe‐associated molecular patterns can influence the differentiation and ...activation of bone cells, little is known about the role of lipoteichoic acid (LTA), a major cell wall component of Gram‐positive bacteria, in the regulation of bone metabolism. In this study, we investigated the effect of LTA on bone metabolism using wild‐type
Staphylococcus aureus
and the LTA‐deficient mutant strain. LTA‐deficient
S. aureus
induced higher bone loss and osteoclast differentiation than wild‐type
S. aureus
. LTA isolated from
S. aureus
(SaLTA) inhibited osteoclast differentiation from committed osteoclast precursors in the presence of various osteoclastogenic factors by downregulating the expression of NFATc1. Remarkably, SaLTA attenuated the osteoclast differentiation from committed osteoclast precursors of TLR2
−/−
or MyD88
−/−
mice and from the committed osteoclast precursors transfected with paired immunoglobulin‐like receptor B‐targeting siRNA. SaLTA directly interacted with gelsolin, interrupting the gelsolin‐actin dissociation which is a critical process for osteoclastogenesis. Moreover, SaLTA suppressed the mRNA expression of dendritic cell‐specific transmembrane protein, ATPase H
+
transporting V0 subunit D2, and
Integrin
, which encode proteins involved in cell‐cell fusion of osteoclasts. Notably, LTAs purified from probiotics, including
Bacillus subtilis
,
Enterococcus faecalis
, and
Lactobacillus
species, also suppressed Pam2CSK4‐ or RANKL‐induced osteoclast differentiation. Taken together, these results suggest that LTAs have anti‐resorptive activity through the inhibition of osteoclastogenesis by interfering with the gelsolin‐actin dissociation and may be used as effective therapeutic agents for the prevention or treatment of inflammatory bone diseases.
A novel method to recursively construct a set of precoded polar codes of various rates and short-to-moderate lengths is presented. The proposed code design method minimizes the successive ...cancellation (SC) decoding error probability estimate under three constraints. The first constraint is the minimum distance requirement to improve the maximum-likelihood (ML) performance of the resulting code and therefore the performance under the SC list (SCL) decoding. The other two constraints introduce preselected supercode and subcode, where the supercode ensures fast computation of the minimum distance and the subcode ensures reduction of the search space size. The supercode is given by the Plotkin sum of shorter codes, which are nested to simplify computation of low-weight codewords. These low-weight codewords are needed to satisfy the minimum distance constraint. The simulation results indicate that the proposed precoded polar codes of lengths 128 and 256 provide a better frame error rate (FER) than polar codes with CRC and e-BCH polar subcodes under the SCL decoding algorithm with the list size <inline-formula> <tex-math notation="LaTeX">8-128 </tex-math></inline-formula>.
We describe the epidemiology of a coronavirus disease (COVID-19) outbreak in a call center in South Korea. We obtained information on demographic characteristics by using standardized epidemiologic ...investigation forms. We performed descriptive analyses and reported the results as frequencies and proportions for categoric variables. Of 1,143 persons who were tested for COVID-19, a total of 97 (8.5%, 95% CI 7.0%-10.3%) had confirmed cases. Of these, 94 were working in an 11th-floor call center with 216 employees, translating to an attack rate of 43.5% (95% CI 36.9%-50.4%). The household secondary attack rate among symptomatic case-patients was 16.2% (95% CI 11.6%- 22.0%). Of the 97 persons with confirmed COVID-19, only 4 (1.9%) remained asymptomatic within 14 days of quarantine, and none of their household contacts acquired secondary infections. Extensive contact tracing, testing all contacts, and early quarantine blocked further transmission and might be effective for containing rapid outbreaks in crowded work settings.
Flexible, transparent and biocompatible polymer nanocomposite films can be fabricated using two-dimensional filler materials, which is of great interest for gas barrier applications. A bio-inspired ...polyvinyl alcohol (PVA) nanocomposite film was fabricated using sulfanilic acid group functionalized MXene (f-MXene) as the reinforcing filler and boric acid (BA) as the crosslinking agent. The f-MXene/BA/PVA nanocomposite films were characterized in terms of their thermal stability, mechanical properties and gas barrier efficacy, and the results indicated these were significantly improved compared to films made from pure PVA and MXene/BA/PVA nanocomposites. This is due to the homogeneous dispersion of the MXene and strong interfacial covalent bonds created by the BA crosslinkers between the f-MXene and the PVA matrix. The nanocomposite film consisting of 0.5 wt% f-MXene and 0.5 wt% BA (0.5 wt% f-MXene/BA/PVA) shows an oxygen permeability of ~0.73 × 10−2 cc∙cm/m2∙day∙atm, which is a reduction of around 69% in gas permeability compared to that of a pure PVA film. In addition, the initial thermal decomposition temperature of the 0.5 wt% f-MXene/BA/PVA nanocomposite film increased from 257.4 °C to 288.2 °C. Futhermore, the tensile strength of the f-MXene/BA/PVA nanocomposite film improved by 67%, and the modulus was also increased by 49%. These results clearly suggest that the MXene/BA/PVA is an effective nanocomposite film when used as a high-performance gas barrier films. The functionalization of MXene and borate-crosslinking represents a practical method to improve the various properties of a range of polymers.
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