Plant regeneration through somatic embryogenesis in root-derived callus of ginseng (Panax ginseng C. A. Meyer)

Summary Callus culture was initiated from expiants of mature root tissues of ginseng (Panax ginseng C.A. Meyer) on MS medium enriched with 2,4-D. The ageing callus produced numerous embryoids in this medium. Reculture of these embryoids in media (1/2 MS or B5) supplemented with benzyladenine and gibberellic acid resulted in profuse plantlet regeneration.     

Genomic and signalling pathway characterization of the NZM panel of melanoma cell lines: A valuable model for studying the impact of genetic diversity in melanoma

Melanoma is a disease associated with a very high mutation burden and thus the possibility of a diverse range of oncogenic mechanisms that allow it to evade therapeutic interventions and the immune system. Here, we describe the characterization of a panel of 102 cell lines from metastatic melanomas (the NZM lines), including using whole‐exome and RNA sequencing to analyse genetic variants and gene expression changes in a subset of this panel. Lines possessing all major melanoma genotypes were identified, and hierarchical clustering of gene expression profiles revealed four broad subgroups of cell lines. Immunogenotyping identified a range of HLA haplotypes as well as expression of neoantigens and cancer–testis antigens in the lines. Together, these characteristics make the NZM panel a valuable resource for cell‐based, immunological and xenograft studies to better understand the diversity of melanoma biology and the responses of melanoma to therapeutic interventions.     

Effects of nitric oxide synthase inhibitors on systemic hypotension, cytokines and inducible nitric oxide synthase expression and lung injury following endotoxin administration in rats

Endotoxin shock is characterized by systemic hypotension, hyporeactiveness to vasoconstrictors and acute lung edema. A nitric oxide synthase (NOS) inhibitor, N^G-monomethyl-L-arginine (L-NMMA) has been shown to be effective in reversing acute lung injury. In the present study, we evaluated the effects of NOS blockade by different mechanisms on the endotoxin-induced changes. In anesthetized rats, lipopolysaccharide (LPS,Klebsiella pneumoniae) was administered intravenously in a dose of 10 mg/kg. LPS caused sustained systemic hypotension accompanied by an eightfold increase of exhaled NO during an observation period of 4 h. After the experiment, the lung weight was obtained and lung tissues were taken for the determination of mRNA expressions of inducible NOS (iNOS), interleukin-1 (IL-1) and tumor necrosis factor--(TNF-). Histological examination of the lungs was also performed. In the control group injected with saline solution, mRNA expressions of iNOS, IL-1 and TNF- were absent. Four hours after LPS, the mRNA expressions of iNOS and IL-1 were still significantly enhanced, but TNF- was not discernibly expressed. LPS also caused a twofold increase in lung weight. Pathological examination revealed endothelial damage and interstitial edema. Various NOS inhibitors were given 1 h after LPS administration. These agents included N-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg), a constitutive NOS and iNOS inhibitor; S,S-1,4-phenylene-bis-(1,2-ethanedinyl) bis-isothiourea dihydrobromide (1,4-PBIT, 10 mg/kg), a relatively specific iNOS inhibitor, and dexamethasone (3 mg/kg), an inhibitor of iNOS expression. These NOS inhibitors all effectively reversed the systemic hypotension, reduced the exhaled NO concentration and prevented acute lung injury. The LPS-induced mRNA expressions of iNOS and IL-1 were also significantly depressed by these NOS inhibitors. Our results suggest that NO production through the iNOS pathway is responsible for endotoxin-induced lung injury. Certain cytokines such as IL-1 are possibly involved. These changes are minimized by NOS inhibitors through different mechanisms.     

Salicylic acid-independent plant defence pathways

Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent pathways. Cross-talk between the salicylic acid-dependent and the salicylic acid-independent pathways provides great regulatory potential for activating multiple resistance mechanisms in varying combinations.     

Ischemia and reperfusion of liver induces eNOS and iNOS expression: effects of a NO donor and NOS inhibitor

The aim of this study was to investigate the role of nitric oxide (NO) in hepatic ischemia-reperfusion (I/R) injury in rats. Immunohistochemistry was used to examine the protein expression of endothelial and inducible nitric oxide synthases (eNOS, iNOS) and nitrotyrosine after I/R challenges to the liver, and blood levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactic dehydrogenase (LDH), hydroxyl radical and NO were measured before ischemia and after reperfusion. Ischemia was induced by occlusion of the common hepatic artery and portal vein for 40 min, followed by reperfusion for 90 min. Reperfusion of the liver induced a significant increase in the blood concentrations of AST, ALT, LDH (n = 8; P < 0.001), hydroxyl radical (n = 8; P < 0.001) and NO (n = 8; P < 0.01). The eNOS, iNOS, nitrotyrosine, SOD1 and SOD2 protein expression was also found to increase significantly after reperfusion (n = 3). Administration of the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) (n = 8) had a protective effect on the I/R-related injury, but the NO donor L-arginine (L-Arg) (n = 8) potentiated the damage caused by I/R. These results suggest that reperfusion of the liver induces expression of NOS, which is related to the elevation of blood NO. The increase in hydroxyl radical concentration was accompanied by an increase in antioxidant enzyme expression (SOD1 and SOD2), and an increase in nitrotyrosine expression was also observed, reflecting the increased production of NO and oxygen radicals. We concluded from the protective effect of L-NAME and the potentiation by L-Arg that NOS expression and increases in NO and hydroxyl radical production have deleterious effects on the response to I/R in the liver.