SANT proteins modulate gene expression by coordinating histone H3KAc and Khib levels and regulate plant heat tolerance

Histone post-translational modifications (PTMs), such as acetylation and recently identified lysine 2-hydroxyisobutyrylation (Khib), act as active epigenomic marks in plants. SANT domain-containing proteins SANT1, SANT2, SANT3, and SANT4 (SANT1/2/3/4), derived from PIF/Harbinger transposases, form a complex with HISTONE DEACETYLASE 6 (HDA6) to regulate gene expression via histone deacetylation. However, whether SANT1/2/3/4 coordinates different types of PTMs to regulate transcription and mediate responses to specific stresses in plants remains unclear. Here, in addition to modulating histone deacetylation, we found that SANT1/2/3/4 proteins acted like HDA6 or HDA9 in regulating the removal of histone Khib in Arabidopsis (Arabidopsis thaliana). Histone H3 lysine acetylation (H3KAc) and histone Khib were coordinated by SANT1/2/3/4 to regulate gene expression, with H3KAc playing a predominant role and Khib acting complementarily to H3KAc. SANT1/2/3/4 mutation significantly increased the expression of heat-inducible genes with concurrent change of H3KAc levels under normal and heat stress conditions, resulting in enhanced thermotolerance. This study revealed the critical roles of Harbinger transposon-derived SANT domain-containing proteins in transcriptional regulation by coordinating different types of histone PTMs and in the regulation of plant thermotolerance by mediating histone acetylation modification

Cyclization reaction of amines with dialkyl carbonates to yield 1,3-oxazinan-2-ones

A number of six-membered cyclic carbamates (oxazinanones) were synthesized from the reaction of a primary amine or hydrazine with a dicarbonate derivative of 1,3-diols in a one-pot reaction, in good yield, short time span, and in the absence of a solvent. The reaction proceeds in two steps: an intermolecular reaction to give a linear intermediate and an intramolecular cyclization to yield the cyclic carbamate. This is the first example of a carbonate reacting selectively and sequentially, firstly at the carbonyl center to form a linear carbamate and then as a leaving group to yield a cyclic carbamate

Auxin Response Factor2 (ARF2) and Its Regulated Homeodomain Gene HB33 Mediate Abscisic Acid Response in Arabidopsis

The phytohormone abscisic acid (ABA) is an important regulator of plant development and response to environmental stresses. In this study, we identified two ABA overly sensitive mutant alleles in a gene encoding Auxin Response Factor2 (ARF2). The expression of ARF2 was induced by ABA treatment. The arf2 mutants showed enhanced ABA sensitivity in seed germination and primary root growth. In contrast, the primary root growth and seed germination of transgenic plants over-expressing ARF2 are less inhibited by ABA than that of the wild type. ARF2 negatively regulates the expression of a homeodomain gene HB33, the expression of which is reduced by ABA. Transgenic plants over-expressing HB33 are more sensitive, while transgenic plants reducing HB33 by RNAi are more resistant to ABA in the seed germination and primary root growth than the wild type. ABA treatment altered auxin distribution in the primary root tips and made the relative, but not absolute, auxin accumulation or auxin signal around quiescent centre cells and their surrounding columella stem cells to other cells stronger in arf2-101 than in the wild type. These results indicate that ARF2 and HB33 are novel regulators in the ABA signal pathway, which has crosstalk with auxin signal pathway in regulating plant growth

miR-668 inhibitor attenuates mitochondrial membrane potential and protects against neuronal apoptosis in cerebral ischemic stroke

Cerebral stroke is a major cause of brain injury due to the production of hypoxic conditions, and new therapeutic interventions are required for its management. Here, we evaluated the protective effect of miR-668 inhibitor against ischemia/reperfusion (I/R)-induced stroke. Cerebral stroke was induced by cerebral artery occlusion in rats, followed by treatment with miR-668 inhibitor for 10 minutes before reperfusion. The neuroprotective effect of miR-668 inhibitor was determined by estimating the neurological deficit score, cerebral infarct area and blood-brain barrier (BBB) permeability. In addition, the levels of inflammatory cytokines, and the expression of NLRP3, zonula occludens-1 (ZO-1), dynamin-related protein 1 (Drp1) and occludin proteins, were estimated by ELISA and Western blotting, respectively. TUNEL assay and immunohistochemical analyses were performed to examine the effects of miR-668 inhibitor against I/R-induced stroke rats. The miR-668 inhibitor treatment group showed reductions in the infarct area, BBB permeability and neurological score compared to the stroke group. The levels of cytokines and reactive oxygen species were reduced in the miR-668 inhibitor treatment group compared to the stroke group. These observations suggested that inhibition of miR-668 reduces neuronal apoptosis by ameliorating the expression of caspase 3, Bax and Bcl-2 protein in I/R stroke rats. The expression of NLRP3, ZO-1 and occludin proteins was attenuated in the brain tissue of the miR-668 inhibitor treatment group compared to the stroke group. Moreover, the phosphorylation of Drp1 protein was reduced in the miR-668 inhibitor group compared to the stroke group. In conclusion, the results of the present study indicated that inhibition of miR-668 prevented neuronal apoptosis in cerebral I/R-induced stroke by modulating mitochondrial function and regulating NLRP3 signalling

Effects of pyrolysis temperature and residence time on physicochemical properties of different biochar types

Here we selected eight types of feedstocks to assess the effects of pyrolysis temperature (300°C, 400°C, 500°C and 600°C) and residence time (0.5, 1, 2, 4, 8 and 24 h), respectively, on the physicochemical properties. The fixed-carbon content, pH value and amount of basic functional groups in biochars increased as the pyrolysis temperature increased from 300°C to 600°C; the opposite trend was found in the biochar yield, adsorption capacity and amount of acidic functional groups. Increasing the residence time at low pyrolysis temperature (300°C) resulted in a gradual reduction in the biochar yield and progressive increase in the pH and iodine adsorption number of biochars. However, increasing the residence time at high pyrolysis temperature (600°C) had little effect on the biochar yield or pH, while it decreased the iodine adsorption number of biochars. Given the effects of pyrolysis conditions on the pH and iodine adsorption number of biochars, low-ash agricultural wastes (e.g. wheat straw) can be pyrolysed at 300°C, 2 h to produce biochar for improving alkaline soils; high-ash agricultural wastes (e.g. sweet potato vine) and forest litter (e.g. fresh leaves of apricot tree) are preferably pyrolysed at 300°C, 4 h to produce biochar for use in acidic soils

Regulatory Mechanisms of Heat Stress Response and Thermomorphogenesis in Plants

As worldwide warming intensifies, the average temperature of the earth continues to increase. Temperature is a key factor for the growth and development of all organisms and governs the distribution and seasonal behavior of plants. High temperatures lead to various biochemical, physiological, and morphological changes in plants and threaten plant productivity. As sessile organisms, plants are subjected to various hostile environmental factors and forced to change their cellular state and morphological architecture to successfully deal with the damage they suffer. Therefore, plants have evolved multiple strategies to cope with an abnormal rise in temperature. There are two main mechanisms by which plants respond to elevated environmental temperatures. One is the heat stress response, which is activated under extremely high temperatures; the other is the thermomorphogenesis response, which is activated under moderately elevated temperatures, below the heat-stress range. In this review, we summarize recent progress in the study of these two important heat-responsive molecular regulatory pathways mediated, respectively, by the Heat Shock Transcription Factor (HSF)–Heat Shock Protein (HSP) pathway and PHYTOCHROME INTER-ACTING FACTOR 4 (PIF4) pathways in plants and elucidate the regulatory mechanisms of the genes involved in these pathways to provide comprehensive data for researchers studying the heat response. We also discuss future perspectives in this field

Self-Assembled Ru(II)-Coumarin Complexes for Selective Cell Membrane Imaging

The cell membrane, as the protecting frontier of cells, is closely related to crucial biological behaviors including cell growth, death, and division. Lots of fluorescent probes have been fabricated to monitor cell membranes due to their simplicity and intuitiveness. However, the efficiency of those traditional probes has been limited by their susceptibility to photobleaching and poor water solubility. In this study, we have reported Ru(II)-coumarin complexes consisting of ruthenium, 1,10-phenanthroline, and coumarin 6 to further form self-assembled nanoprobes, for cell membrane targeting and imaging. The fluorescent property could be switchable from red to green through the dynamic disassembly of nanoprobes. Compared with commercial Dil, biocompatible nanoprobes exhibited superior stability for long-term cell imaging, along with remarkedly reduced background interference. Therefore, our self-assembled nanoprobe provides a powerful solution for investigating lipid trafficking with optical imaging