Pre-drought effects on northern temperate trees and vine invasion in forest gaps hindering regeneration.

Northern temperate coniferous forests serve as crucial connectors between boreal and temperate forests, yet they are vulnerable to various stressors such as climate change and human activities. Severe drought poses a significant threat to plant species within these forests, prompting recent research into its impacts. However, many studies lack explicit definitions of post-disturbance vegetation processes and fail to identify potential interactions with disturbance factors, necessitating comprehensive discussions. This study examines the effects of drought on tree growth patterns of the main dominant species in northern temperate regions: Abies nephrolepis and Picea jezoensis, along with two commonly associated Betula ermanii, and Quercus mongolica. Additionally, new disturbance factors in forests inhabited by these species (A. nephrolepis and P. jezoensis) were evaluated based on community classification. The study sites were located in the Mt. Baekdu (Changbai) and South Korea regions, which are positioned at the southern limit of the phytogeographical patterns of target species. Results indicate that A. nephrolepis and P. jezoensis exhibit high levels of recovery and resilience, while B. ermanii and Q. mongolica demonstrate high resistance. Species-specific responses align with drought intensity, with resistance, recovery, and resilience decreasing notably with increasing pre-drought radial growth. South Korean forests, the invasion of the vine species Tripterygium regelii after the death of A. nephrolepis in the overstory vegetation threatens the regeneration of new trees. However, certain environmental factors, such as high rock exposure and dense overstory canopy, limit vine invasion. Based on the results, pre-drought radial growth emerges as a key determinant in how trees respond to drought. Additionally, the results suggest the potential for new disturbances to emerge in forest gaps due to overstory vegetation mortality induced by global warming. These findings contribute to a deeper understanding of increasing drought stress, aid in identifying climate refugia, and inform conservation priorities based on habitat characteristics.

Effect of nitro-conjugated linoleic acid on the inflammatory response of murine macrophages activated with lipopolysaccharide derived from Prevotella intermedia.

Nitro-conjugated linoleic acid (NO2-CLA) has been observed to manifest salutary signaling responses, including anti-inflammatory and antioxidant properties. Here, the authors have explored the influence and underlying mechanisms of NO2-CLA on the proinflammatory reaction of murine macrophages that were challenged with lipopolysaccharide (LPS) derived from Prevotella intermedia, a putative periodontopathic bacterium. Treatment of LPS-activated RAW264.7 cells with NO2-CLA notably dampened the secretion of iNOS-derived NO, IL-1ß and IL-6 as well as their gene expressions and significantly enhanced the markers for M2 macrophage polarization. NO2-CLA promoted the HO-1 expression in cells challenged with LPS, and tin protoporphyrin IX, an HO-1 inhibitor, significantly reversed the NO2-CLA-mediated attenuation of NO secretion, but not IL-1ß or IL-6. We found that cells treated with NO2-CLA significantly increased mRNA expression of PPAR-γ compared to control cells, and NO2-CLA significantly reverted the decrease in PPAR-γ mRNA caused by LPS. Nonetheless, antagonists to PPAR-γ were unable to reverse the NO2-CLA-mediated suppression of inflammatory mediators. In addition, NO2-CLA did not alter the p38 and JNK activation elicited by LPS. Both NF-κB reporter activity and IκB-α degradation caused by LPS were notably diminished by NO2-CLA. NO2-CLA was observed to interrupt the nuclear translocation and DNA binding of p50 subunits caused by LPS with no obvious alterations in p65 subunits. Further, NO2-CLA attenuated the phosphorylation of STAT1/3 elicited in response to LPS. We propose that NO2-CLA could be considered as a possible strategy for the therapy of periodontal disease, although additional researches are certainly required to confirm this.

Nifedipine attenuates alveolar bone destruction and improves trabecular microarchitectures in mice with experimental periodontitis.

Studies have shown that nifedipine exerts anti-inflammatory and immunosuppressive actions in addition to being a calcium channel blocker. The present study was performed to explore the influence of nifedipine on alveolar bone destruction in mice with experimental periodontitis by evaluating morphological information acquired from micro-computed tomography analysis. BALB/c mice were randomly assigned into four groups: control (C) group; experimental periodontitis (E) group; experimental periodontitis + 10 mg/kg dose of nifedipine (EN10) group; and experimental periodontitis + 50 mg/kg dose of nifedipine (EN50) group. Periodontitis was induced by oral inoculation with Porphyromonas gingivalis over a 3-week time period. Nifedipine significantly mitigated the loss of alveolar bone height as well as increase of root surface exposure induced by experimental periodontitis. Additionally, the reduction in the bone volume fraction associated with P. gingivalis infection was significantly recovered upon nifedipine treatment. Further, nifedipine attenuated P. gingivalis-induced deteriorations in the trabeculae-associated parameters. Significant difference was evident between Groups EN10 and EN50 in both the extent of alveolar bone loss and microstructural parameters assessed, except trabecular separation and trabecular number. Nifedipine appeared to have good performance in ameliorating bone loss in mice with induced periodontitis. Nifedipine may be utilized in the clinical management of periodontitis, though further research is indicated to verify the therapeutic effect.

Carbon monoxide-releasing molecule-401, a water-soluble manganese-based metal carbonyl, suppresses Prevotella intermedia lipopolysaccharide-induced production of nitric oxide in murine macrophages.

CONTEXT: Many reports in the literature have suggested the therapeutic value of carbon monoxide-releasing molecules (CORMs) against various diseases. However, to date, little is known about their possible influence on periodontal disease. OBJECTIVE: This study was performed to investigate the influence of CORM-401 on the generation of nitric oxide (NO) in murine macrophage cells activated with lipopolysaccharide (LPS) derived from Prevotella intermedia, a pathogen associated with periodontal disease. MATERIALS AND METHODS: LPS was isolated by the hot phenol-water method. Culture supernatants were analyzed for NO. Real-time PCR and immunoblotting were conducted to quantify mRNA and protein expression, respectively. NF-κB-dependent SEAP levels were estimated by reporter assay. DNA-binding of NF-κB was also analyzed. RESULTS: CORM-401 caused an apparent suppression of NO production through inhibition of iNOS at both the mRNA and protein levels in RAW264.7 cells stimulated with P. intermedia LPS. CORM-401 upregulated the expression of both the HO-1 gene and its protein in LPS-activated cells, and treatment with the HO-1 inhibitor significantly reversed the attenuating influence of CORM-401 against LPS-induced generation of NO. CORM-401 caused an apparent attenuation of NF-κB-dependent SEAP release induced by LPS. IκB-α degradation and nuclear translocation of NF-κB p50 subunit induced by LPS were significantly reduced by CORM-401. Additionally, CORM-401 significantly attenuated DNA-binding of p65 and p50 induced by LPS. CORM-401 attenuated NO generation induced by P. intermedia LPS independently of PPAR-γ, JNK, p38 and STAT1/3. CONCLUSION: The modulation of host inflammatory response by CORM-401 might be of help in the therapy of periodontal disease.

Nitrooleic acid inhibits macrophage activation induced by lipopolysaccharide from Prevotella intermedia.

The hypothesis of the present study was that nitro-fatty acids (NO2-FAs) would suppress inflammation associated with periodontal disease. To test this hypothesis, we investigated the influence of nitrooleic acid, a prototypical NO2-FA, on the inflammatory response of murine macrophages activated with lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen associated the etiology of different types of periodontal diseases. LPS was prepared from P. intermedia cells by using phenol-water protocol. Culture supernatants were assayed for nitric oxide (NO), interleukin-1ß (IL-1ß), and IL-6. Real-time polymerase chain reaction and immunoblotting analyses were performed to quantify messenger RNA and protein expression, respectively. The secreted embryonic alkaline phosphatase reporter assay was performed to measure NF-κB activation. The transcription factor assay kit was used to measure DNA-binding of NF-κB subunits. Findings obtained from the present study revealed that nitrooleic acid suppresses the generation and messenger RNA expression of inducible NO synthase-derived NO, IL-1ß, and IL-6 in RAW264.7 cells activated with P. intermedia LPS and promotes macrophage polarization toward anti-inflammatory M2 phenotype. We also found that nitrooleic acid exerts its effect via heme oxygenase-1 induction and suppression of NF-κB signaling. The inhibition of NO and proinflammatory cytokine production by nitrooleic acid was independent from PPAR-γ, JNK, p38, and STAT1/3. Nitrooleic acid may represent a novel class of agent as a host modulator which has therapeutic benefit in periodontal disease, though more work is needed to confirm this.

Genome-Wide Identification and Genetic Variations of the Starch Synthase Gene Family in Rice.

Starch is a major ingredient in rice, and the amylose content of starch significantly impacts rice quality. OsSS (starch synthase) is a gene family related to the synthesis of amylose and amylopectin, and 10 members have been reported. In the present study, a synteny analysis of a novel family member belonging to the OsSSIV subfamily that contained a starch synthase catalytic domain showed that three segmental duplications and multiple duplications were identified in rice and other species. Expression data showed that the OsSS gene family is involved in diverse expression patterns. The prediction of miRNA targets suggested that OsSS are possibly widely regulated by miRNA functions, with miR156s targeted to OsSSII-3, especially. Haplotype analysis exhibited the relationship between amylose content and diverse genotypes. These results give new insight and a theoretical basis for the improved amylose content and eating quality of rice.

Genome-Wide Association Study of Root System Development at Seedling Stage in Rice.

Root network structure plays a crucial role in growth and development processes in rice. Longer, more branched root structures help plants to assimilate water and nutrition from soil, support robust plant growth, and improve resilience to stresses such as disease. Understanding the molecular basis of root development through screening of root-related traits in rice germplasms is critical to future rice breeding programs. This study used a small germplasm collection of 137 rice varieties chosen from the Korean rice core set (KRICE_CORE) to identify loci linked to root development. Two million high-quality single nucleotide polymorphisms (SNPs) were used as the genotype, with maximum root length (MRL) and total root weight (TRW) in seedlings used as the phenotype. Genome-wide association study (GWAS) combined with Principal Components Analysis (PCA) and Kinship matrix analysis identified four quantitative trait loci (QTLs) on chromosomes 3, 6, and 8. Two QTLs were linked to MRL and two were related to TRW. Analysis of Linkage Disequilibrium (LD) decay identified a 230 kb exploratory range for detection of candidate root-related genes. Candidates were filtered using RNA-seq data, gene annotations, and quantitative real-time PCR (qRT-PCR), and five previously characterized genes related to root development were identified, as well as four novel candidate genes. Promoter analysis of candidate genes showed that LOC_Os03g08880 and LOC_Os06g13060 contained SNPs with the potential to impact gene expression in root-related promoter motifs. Haplotype analysis of candidate genes revealed diverse haplotypes that were significantly associated with phenotypic variation. Taken together, these results indicate that LOC_Os03g08880 and LOC_Os06g13060 are strong candidate genes for root development functions. The significant haplotypes identified in this study will be beneficial in future breeding programs for root improvement.

Genome-wide association study reveals candidate genes related to low temperature tolerance in rice (Oryza sativa) during germination.

In this study, relative germination percentage (RGP) and delayed mean germination time (DMGT) were measured in various rice accessions at the germination stage and carried out association analysis to identify candidate genes related to low temperature germination (LTG) using a natural population comprising 137 rice cultivars and inbred lines selected from the Korean rice core set. Genome-wide association study using ~ 1.44 million high-quality SNPs, which were identified by re-sequencing all rice collections, revealed 48 candidate genes on chromosome 10 and 55 candidate genes on chromosome 11 in the high peak SNP sites of associated loci for RGP and DMGT, respectively. By detecting highly associated variations located inside genic regions and performing functional annotation of the genes, we detected 23 candidate genes for RGP and 18 genes for DMGT for LTG. In addition, the haplotype and sequence analysis of the candidate gene (Os10g0371100) with RGP trait and the candidate gene (Os11t0104240-00) with DMGT revealed correlation between sequences of functional variations and phenotypes. Several novel LTG-related candidate genes previously were known for the function during rice germination and uncovered their substantial natural variations. These candidate genes represent valuable resources for molecular breeding and genetic improvement of cold tolerance during rice germination.

Next-generation sequencing yields the complete chloroplast genome of C. goeringii acc. smg222 and phylogenetic analysis.

Spring orchid (Cymbidium goeringii) is one of the most important species belonging to Orchidaceae owing to its aesthetic appeal, fragrant flowers and ideal characteristics for using as a houseplant. In this study, the complete chloroplast genome of Korean C. goeringii acc. smg222 was determined by Illumina sequencing. The circular double-stranded DNA of 148,441 bp consisted of two inverted repeat regions of 25,610 bp each, a large single copy region of 83,311 bp, and a small single copy region of 13,910 bp. The genome contained 122 genes, of which 104 were unique and 18 were duplicated within the IRs. The 104 unique genes included 70 protein-coding genes, 30 distinct tRNA genes, and four rRNA genes. Phylogenetic tree analysis revealed that C. goeringii acc. smg222 was clustered with Cymbidium kanran, a cymbidium species native to Korea.